Medical mcq's

Usmle-mcq's-9

2008-03-17T08:25:00.001-07:00

)<1>A 68-year-old female who recently had a cholecystectomy develops a
fever of 103°F and has persistent drainage from her biliary catheter.
She is given cephalothin and gentamicin for 10 days. Her serum creatinine
level increases to 7.6 mg/dL. Her urine output is 1.3 L/day and has not
diminished over the past few days. There is no history of hypotension
and her vital signs are normal. Renal ultrasonography shows no evidence
of obstruction. The most likely etiology of the patient's condition is
A. acute glomerulonephritis
B. acute renal failure secondary to cephalothin
C. gentamicin nephrotoxicity
D. renal artery occlusion
E. sepsis
Answer
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<2>A 45-year-old man presents to a physician with back pain and facial pain.
Physical examination demonstrates coarse facial features and kyphosis.
Laboratory examination is remarkable for elevated alkaline phosphatase
. X-ray studies demonstrate skull thickening with narrowing of foramina,
and bowing of the femur and tibia. Bone biopsy reveals a mosaic
pattern of bone spicules with prominent osteoid seams. Which of
the following neoplasms occurs at an increased frequency in patients
with this disorder?
A. Astrocytoma
B. Hodgkin's lymphoma
C. Meningioma
D. Non-Hodgkin's lymphoma
E. Osteosarcoma
Answer
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<3> Which of the labeled structures is responsible for the secretion
of renin?
A. A
B. B
C. C
D. D
E. E
Answer

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<4>A 42-year-old African-American man sustains severe injuries in an
automobile accident and is admitted to the intensive care unit.
Examination of a peripheral blood smear on the 3rd day of admission
reveals helmet cells, schistocytes, and decreased platelets. Which of
the following is most strongly suggested by these findings?
A. Autoimmune hemolysis
B. Disseminated intravascular coagulation (DIC)
C. Hereditary spherocytosis
D. Megaloblastic anemia
E. Sickle cell anemia
Answer
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<5>A 12-month-old child is diagnosed with an atrial septal defect.
What is the most common cause of such a congenital heart malformation?
A. Failure of formation of the septum primum
B. Failure of formation of the septum secundum
C. Incomplete adhesion between the septum primum and septum secundum
D. Malformation of the membranous interventricular septum
E. Malformation of the muscular interventricular septum
Answer
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<6>A 72-year-old man with prostate cancer is treated with leuprolide.
What is the mechanism of action of this drug?
A. It inhibits 5a-reductase
B. It is a competitive antagonist at androgen receptors
C. It is a competitive inhibitor of LH
D. It is a synthetic analog of GnRH
E. It is a testosterone agonist
Answer
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<7>An XX genotypic infant is born with ambiguous genitalia. Laboratory
examination reveals hypoglycemia, hyperkalemia, and salt wasting. S
erum 17-OH progesterone is markedly increased. Which of the following is
the most likely diagnosis?
A. 5-alpha-reductase deficiency
B. 11-beta-hydroxylase deficiency
C. 17-alpha-hydroxylase deficiency
D. 21-hydroxylase deficiency
E. Complete androgen resistance
Answer
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<8>A 57-year-old fisherman with a history of alcoholism is hospitalized in
Gulfport, Mississippi with a 1-day history of severe, watery diarrhea after
eating several raw oysters. He is badly dehydrated on admission, and within
12 hours, he becomes severely hypotensive and dies. Which of the following
pathogens is the most likely cause of this man's death?
A. Citrobacter diversus
B. Enterotoxigenic E. coli
C. Providencia stuartii
D. Vibrio cholerae
E. Vibrio vulnificus
Answer
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<9>An Hispanic male is referred to the dermatology clinic of a major medical
center. On physical examination, the man has several disfiguring lesions on
his face and there is loss of cutaneous sensation to fine touch, pain, and
temperature. An acid-fast organism is observed in scrapings from a skin
lesion. Which of the following organisms is the most likely cause of this
patient's disease?
A. Bartonella henselae
B. Listeria monocytogenes
C. Mycobacterium avium-intracellulare
D. Mycobacterium leprae
E. Nocardia asteroides
Answer
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<10>Microscopic examination of a section of a normal young adult ovary
reveals large numbers of unusually large cells surrounded by a single
layer of flat epithelial cells. In which phase of the cell cycle are
these cells arrested?
A. Diplotene stage of the 1st meiotic division
B. Diplotene stage of the 2nd meiotic division
C. Metaphase stage of mitosis
D. Prophase stage of mitosis
E. Prophase stage of the 2nd meiotic division
Answer
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<11>A 3-year-old child is seen by a pediatrician because he has developed
multiple isolated lesions on his face and neck. Physical examination
reveals many lesions up to 4 cm in diameter with golden crusts, while
in other sites small blisters and weeping areas are seen. Which of the
following is the most likely diagnosis?
A. Aphthous ulcers
B. Erysipelas
C. Herpes simplex I
D. Impetigo
E. Measles
Answer
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<12>A 2-year-old-boy is brought to the pediatrician by his mother because
he has had several episodes of rectal bleeding. Evaluation with a
technetium-99m perfusion scan reveals a 3-cm ileal outpouching located
60 cm from the ileocecal valve. This structure likely contains which of
the following types of ectopic tissue?
A. Duodenal
B. Esophageal
C. Gastric
D. Hepatic
E. Jejunal
Answer
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<13>A 19-year-old college student presents to the student health clinic
complaining of weakness, malaise, and a chronic cough. He has a fever of
100 degrees F and a dry cough; no sputum can be obtained for laboratory
analysis, so a bronchial lavage is performed and the washings are
submitted to the laboratory. The laboratory reports that the organism
is "slow-growing." Serodiagnosis reveals Strep MG agglutinins in the
patient's serum. Which of the following organisms is the most likely
cause of this student's illness?
A. Klebsiella pneumoniae
B. Mycoplasma pneumoniae
C. Parainfluenza virus
D. Respiratory syncytial virus
E. Streptococcus pneumoniae
Answer
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<14>A 52-year-old male is brought into the emergency room by his wife
because he has been complaining of a severe headache. Physical exam
reveals ptosis of the right eyelid with the right eye facing down and out.
There is a fixed and dilated right pupil with an inability to accommodate.
Subarachnoid blood appears on noncontrast CT scan. Magnetic resonance
angiography (MRA) would be expected to reveal an aneurysm of which of
the following vessels?
A. Anterior cerebral artery
B. Anterior choroidal artery
C. Anterior communicating artery
D. Middle cerebral artery
E. Ophthalmic artery
F. Posterior communicating artery
G. Posterior inferior cerebellar artery
Answer
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<15>A 24-year-old graduate student presents to a physician with complaints
of severe muscle cramps and weakness with even mild exercise. Muscle
biopsy demonstrates glycogen accumulation, but hepatic biopsy is
unremarkable. Which of the following is the most likely diagnosis?
A. Hartnup's disease
B. Krabbe's disease
C. McArdle's disease
D. Niemann-Pick disease
E. Von Gierke's disease
Answer

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<16>A baby is born with a flat facial profile, prominent epicanthal folds,
and simian crease. She vomits when fed, and upper GI studies demonstrate
a "double bubble" in the upper abdomen. Which of the following
cardiovascular abnormalities might this child also have?
A. Atrial septal defect
B. Berry aneurysm
C. Coarctation of the aorta
D. Endocardial cushion defect
E. Tetralogy of Fallot
Answer
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<17>An asymptomatic, 24-year-old African-American woman in her second
trimester of pregnancy has the following laboratory findings: Based
on the laboratory data, which of the following tests is necessary for fur
ther evaluation of this patient?
A. Creatinine clearance
B. Oral glucose tolerance test
C. Serum ferritin
D. Sickle cell preparation
E. No further study is necessary
Answer
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<18>Endometrial biopsy demonstrates a thick endometrium with long,
coiled glands lined by a columnar epithelium with prominent cytoplasmic
vacuoles adjacent to the gland lumen. Earlier in the menstrual cycle,
the glands were much smaller and were lined with cells that did not
have vacuoles. Which of the following hormones is primarily responsible
for inducing this change in appearance?
A. Aldosterone
B. Cortisol
C. Estrogen
D. Progesterone
E. Thyroxine

Answer
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<19>A 28-year-old man discovers a mass in his neck while buttoning
his shirt collar. Physical examination reveals a 2 cm mass in one
thyroid lobe, which is "cold" on scintiscan. Aspiration of the
nodule demonstrates small "solid balls" of neoplastic follicular
cells. Careful examination of these tissue balls reveals that
they contain microscopic blood vessels and fibrous stroma in
their centers. Which of the following is the most likely diagnosis?
A. Follicular carcinoma
B. Hashimoto's disease
C. Medullary carcinoma
D. Papillary carcinoma
E. Thyroid adenoma
Answer
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<20>Nissl bodies correspond to which of the following cytoplasmic organelles?
A. Golgi apparatus
B. Mitochondria
C. Nucleoli
D. Rough endoplasmic reticulum
E. Smooth endoplasmic reticulum
Answer
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<21>A 40-year-old man with sleep apnea participates in a sleep study.
During his evaluation, normal sawtooth waves are observed on his EEG
tracing. This pattern is associated with which period of sleep?
A. REM
B. Stage 1
C. Stage 2
D. Stage 3
E. Stage 4
Answer
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<22>A United Nations representative from a poor African country has an
influenza-like illness that resolves in a few days. Less than a week later,
however, he develops muscle pain, spasms, and sensory disturbances.
Two days after this, flaccid paralysis occurs. Which of the following
is most likely to be immediately life-threatening in this patient?
A. Acute renal failure
B. Bowel paralysis
C. Fulminant liver failure
D. Gastrointestinal bleeding
E. Respiratory paralysis
Answer
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<23>What is the normal myeloid to erythroid ratio in bone marrow?
A. 1:1
B. 1:3
C. 1:10
D. 3:1
E. 10:1
Answer
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<24>A 45-year-old male complains of fatigue and increased frequency of
urination. Questioning reveals that he is somewhat confused. Physical
examination reveals a 5'10", 240 lb. individual whose fat is centrally
distributed. Urine is positive for glucose, but negative for ketones.
A blood sample drawn from this patient is likely to exhibit which of
the following compared to that of a normal individual?
A. Decreased concentration of C-peptide
B. Decreased pH
C. Increased antibodies against islet cell proteins
D. Increased concentration of b-hydroxybutyrate
E. Increased osmolarity
Answer
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<25>At which of the following ages does fetal movement first occur?
A. 1 month
B. 2 months
C. 4 months
D. 6 months
E. 7 months
Answer
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<26>A child with retinoblastoma is found to have a 13q14 deletion.
The Rb gene, which resides at this locus, produces which kind of
tumor-associated protein?
A. Cell cycle regulator
B. Growth factor
C. Growth factor-binding protein
D. Growth factor receptor
E. Transcription activator
Answer
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<27>A 29-year-old woman is involved in an automobile accident, and
is taken to the emergency room by paramedics. X-rays reveal a
fracture of her pelvis. During the healing of the pelvic fracture,
the obturator nerve becomes entrapped in the bone callus. Compression
of this nerve by the growing bone may result in weakness of which of
the following muscles?
A. Adductor magnus
B. Biceps femoris
C. Rectus femoris
D. Sartorius
E. Vastus medialis
Answer
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<28>An African child develops massive unilateral enlargement of his lower
face in the vicinity of the mandible. Biopsy demonstrates sheets of
medium-sized blast cells with admixed larger macrophages. This
type of tumor has been associated with which of the following?
A. Epstein-Barr virus and t(8;14)
B. Hepatitis B and t(9;22)
C. Herpesvirus and CD5
D. Human immunodeficiency virus and CD4
E. Human papillomavirus and t(2;5)
Answer
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<29>A 57-year-old man presents for a routine physical. His blood pressure
is 161/98 mm Hg. The patient's only complaint is that over the past
several months he has had difficulty urinating. His urine stream is
intermittent, and he has recently begun experiencing nocturia and
profound urinary urgency. Digital rectal exam reveals diffuse
enlargement of the prostate. Which of the following agents
would be most likely to effectively treat the man's urinary
tract symptoms as well as his hypertension?
A. Finasteride
B. Guanfacine
C. Hydralazine
D. Labetalol
E. Terazosin
Answer
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<30>A 54-year-old male with extensive, severe atherosclerosis sustains
a thrombotic occlusion of the celiac trunk. The organs that receive
their blood supply from this artery continue to function normally.
Anastomoses between which of the following pairs of arteries would
explain this phenomenon?
A. Left gastric artery and right gastric artery
B. Left gastroepiploic artery and right gastroepiploic artery
C. Proper hepatic artery and gastroduodenal artery
D. Right colic artery and middle colic artery
E. Superior pancreaticoduodenal artery and inferior pancreaticoduodenal artery
Answer
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<31>A cardiovascular pharmacologist is researching the effects of new
compounds on arteriolar resistance. Drug X maximally increases vascular
resistance by 50% at a dose of 20 mg/mL. Drug Y maximally increases
vascular resistance by 75% at a dose of 40 mg/mL. Which of the
following conclusions can the researcher draw from this experiment?
A. Drug X has a smaller volume of distribution than Drug Y
B. Drug X has a shorter half-life than Drug Y
C. Drug X is less efficacious than Drug Y
D. Drug X is less potent than Drug Y
E. Drug X has a lower LD50 than Drug Y
Answer
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<32>A 74-year-old woman, in otherwise good health, tripped and injured
her right leg 2 days previously and has been bedridden since the accident
. Two hours ago, she became delirious. On physical examination, her
temperature is 99 F, blood pressure is 120/70 mm Hg, heart rate is
110, and respiratory rate is 32. Pulse oximetry shows an oxygen
saturation of 80%, and a chest x-ray film is normal. Which of the
following is the most likely diagnosis?
A. Acute cerebral hemorrhage
B. Acute cerebral infarction
C. Myocardial infarction
D. Pulmonary infarction
E. Pulmonary thromboembolism
Answer
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<33>A 25-year-old pregnant woman complains to her obstetrician of dysuria.
Microscopic examination of the urine demonstrates many gram-negative rods,
many neutrophils, and a few WBC casts. Which of the following is the
specific significance of the presence of WBC casts?
A. One or both kidneys are involved in the infection
B. One or both ureters are involved in the infection
C. The bladder is involved in the infection
D. The urethra is involved in the infection
E. The uterus is involved in the infection
Answer
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<34>A 45-year-old female with a long history of progressive myopia develops
sudden patchy loss of vision in her right eye. She is very alarmed
and rushes to her family doctor. Funduscopic examination
reveals a large retinal detachment in the right eye.
The retina in the left eye is normal. When
the pupillary light reflex is tested by shining a light
in the right eye, the physician would likely note
A. constriction of the right pupil and constriction of the left
B. constriction of the right pupil and dilatation of the left
C. dilatation of the right pupil and constriction of the left
D. dilatation of the right pupil and dilatation of the left
E. no reaction of the right pupil and constriction of the left
Answer
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<35>Physical examination of a young boy reveals discharge of urine
from the umbilicus. The physician concludes that the urachus has failed
to fuse. Which of the following structures is the normal adult remnant
of the fused urachus?
A. Lateral umbilical fold
B. Medial umbilical fold
C. Medial umbilical ligament
D. Median umbilical fold
E. Median umbilical ligament
Answer
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<36> In this section of a healing bone fracture, which of the following
best describes the cell at the arrow?
A. Apoptotic cell
B. Bone-lining macrophage
C. Dividing osteoblast
D. Necrotic cell
E. Typical osteoblast
Answer

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<37>A retarded 45-year-old man living in Mexico becomes ill with pneumonia
and his family brings him across the border to the United States. He
succumbs to his illness and an autopsy is performed. Neuropathological
examination of his brain reveals neuritic plaques and neurofibrillary
tangles. Which of the following was the most likely cause of this man's
retardation?
A. Down's syndrome
B. Edwards' syndrome
C. Fragile X syndrome
D. Patau syndrome
E. Supernumerary Y syndrome

Answer
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<38>A 59-year-old woman presents with complaints of "feeling tired." She
also admits to frequent headaches, which occur on one side and are
throbbing. Physical examination is remarkable for a temperature of
100°F (37.8°C) and tenderness over both temples. Laboratory tests
reveal a slightly decreased hematocrit and an elevated erythrocyte
sedimentation rate. This patient should be treated aggressively to
prevent the development of
A. blindness
B. deafness
C. loss of tactile sensation
D. loss of the ability to speak
E. paralysis
Answer
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<39>A newborn baby has projectile vomiting shortly after each feeding. It is determined that there is obstruction of the digestive tract as a result of an annular pancreas. Annular pancreas is a result of an abnormality in which of the following processes?
A. Rotation of the dorsal pancreatic bud around the first part of the duodenum
B. Rotation of the dorsal pancreatic bud around the second part of the duodenum
C. Rotation of the dorsal pancreatic bud around the third part of the duodenum
D. Rotation of the ventral pancreatic bud around the first part of the duodenum
E. Rotation of the ventral pancreatic bud around the second part of the duodenum
Answer
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<40>A debilitated 72-year-old woman develops dry cough, fever, headache,
and muscular pains. She treats herself with aspirin and ampicillin without
any improvement. Her children take her to a local hospital, where chest
x-ray films reveal scattered opacities, suggestive of interstitial
infiltration. Laboratory investigations demonstrate the presence of
cold agglutinins. She is treated with erythromycin, and her symptoms
rapidly improve. Which of the following is the most likely etiologic
agent of this patient's condition?
A. Influenza virus
B. Mycoplasma pneumoniae
C. Pneumocystis carinii
D. Respiratory syncytial virus
E. Streptococcus pneumoniae
Answer
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<41>Which of the following hormones is most important in initiating gall
bladder contraction?
A. Cholecystokinin (CCK)
B. Gastric inhibitory peptide (GIP)
C. Gastrin
D. Secretin
E. Vasoactive intestinal polypeptide (VIP)
Answer
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>42>A patient complains to her family physician that "When it's time to go
to work, I just can't seem to get out of the house. I have a lot of
windows, and I need to check them all three times. Then, I can never
be sure the door is locked, so I check it 3 times. I've been late for
work a few times, but this is the only way I can be sure the house is
safe. Sometimes I think I'm going to go crazy." Which of the following
is the most likely diagnosis?
A. Adjustment disorder with anxiety
B. Agoraphobia without history of panic disorder
C. Generalized anxiety disorder
D. Obsessive compulsive disorder
E. Panic disorder with agoraphobia
Answer
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<43>A 32-year-old male, infected with HIV, is diagnosed with Hodgkin's
lymphoma. If the patient's CD4 count is 505/mm3, which of the following
agents would be suitable for the treatment of this patient's
lymphoma
without further compromising his immune system?
A. Busulfan
B. Cisplatin
C. Cyclophosphamide
D. Paclitaxel
E. Vincristine
Answer
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<44>A 62-year-old Type 2 diabetic patient presents with complaints of
malaise, myalgias, respiratory distress, and increased somnolence. If
laboratory examination reveals an anion gap of 26 mmol/L, HCO3- of 17
mmol/L and an arterial blood pH of 7.27, the patient is most likely
receiving
A. glyburide
B. metformin
C. repaglinide
D. miglitol
E. troglitazone
Answer
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<45>A 24-year-old delivery driver is involved in an accident and sustains
a wide abrasion over his left elbow. The abrasion results in the total
loss of epidermis over a large area of his left arm, but one month
later, the abrasion has healed, with regrowth of the epidermis.
Which of the following mechanisms accounts for the restoration
of the epidermis over the abraded area?
A. Growth of epidermis from hair follicles and sweat glands in the dermis
B. Migration of endothelial cells from newly grown capillaries
C. Transformation of dermal fibroblasts into epidermal cells
D. Transformation of macrophages into epidermal cells
E. Transformation of melanocytes into epidermal cells
Answer
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<46> The diagram above shows spirographic tracings of forced expirations
from two different individuals. Trace X was obtained from a person with
healthy lungs. Which of the following is most likely represented by
trace Y?
A. Asthma
B. Bronchospasm
C. Emphysema
D. Interstitial fibrosis
E. Old age
Answer

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<47>A patient has multiple, pearly papules on the face. Biopsy shows a
malignant tumor. Which of the following features would most likely be
seen on microscopic examination?
A. Cytoplasmic viral inclusions
B. Keratin "pearls"
C. Melanin
D. Palisading nuclei
E. S-100 positivity
Answer
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<48>A neonate develops marked unconjugated hyperbilirubinemia. No hemolysis
can be demonstrated and other liver function tests are normal. There is no
bilirubin found in the urine. This infant's condition continues to
deteriorate and he dies at 2 weeks of age. To which of the following
conditions did the infant most likely succumb?
A. Crigler-Najjar syndrome, Type I
B. Crigler-Najjar syndrome, Type II
C. Dubin-Johnson syndrome
D. Gilbert's syndrome
E. Rotor syndrome
Answer
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<49>A 41-year-old woman presents with chronic widespread musculoskeletal
pain, fatigue, and frequent headaches. She states that her musculoskeletal
pain improves slightly with exercise. On examination, painful trigger
points are produced by palpitation of the trapezius and lateral
epicondyle of the elbow. If objective signs of inflammation are
absent and laboratory studies are normal, this patient would most
likely be responsive to which of the following drugs?
A. Amitriptyline
B. Cefaclor
C. Naproxen
D. Oxycodone
E. Prednisone
Answer
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<50>A 29-year-old medical student developed a positive PPD (purified protein
derivative) test. She was started on isoniazid (INH) and rifampin
prophylaxis. Three months into her therapy, she began to experience
muscle fasciculations and convulsions. Administration of which of
the following vitamins might have prevented these symptoms?
A. Niacin
B. Pyridoxine
C. Riboflavin
D. Thiamine
E. Vitamin C
Answer
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Answers
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1The correct answer is C. A small percentage of patients (5% to 10%) develop a nonoliguric form of acute renal failure when treated with aminoglycosides such as gentamicin. Gentamicin can accumulate in the kidney to produce a delayed form of acute renal failure resulting in an elevation of the serum creatinine level. The nonoliguric form of renal failure, seen in this patient, is the typical presentation for gentamicin nephrotoxicity.
Acute glomerulonephritis (choice A) is typically associated with hypertension and the appearance of an active urinary sediment containing casts and red blood cells.
Cephalothin (choice B) is a first-generation cephalosporin commonly used in the treatment of severe infection of the genitourinary tract, gastrointestinal tract, and respiratory tract, as well as skin infections. This antibiotic can produce an acute interstitial nephritis; however, the patient's presentation is consistent with gentamicin nephrotoxicity. Interstitial nephritis is commonly associated with the development of acute renal failure, fever, rash, and eosinophilia.
Renal artery occlusion (choice D) is commonly caused by thrombosis or embolism. The clinical features of acute renal artery occlusion are hematuria, flank pain, fever, nausea, elevated LDH, elevated SGOT and acute renal failure.
Since the patient has normal vital signs and no history of hypotension, a diagnosis of sepsis (choice E) is unlikely.
--------------------------------------------------------------------------------2The correct answer is E. The phrase "mosaic pattern" of newly formed woven bone is a specific tip-off for Paget's disease of bone, and is not seen in other bone conditions. The clinical and radiologic presentation are typical; an increased hat size may also be a clue. In its early stages, Paget's disease is characterized by osteolysis, producing patchwork areas of bone resorption with bizarre, large osteoclasts. In the middle stage of the disease, secondary osteoblastic activity compensates with new bone formation, producing the mosaic pattern. In late Paget's, the bones are dense and osteosclerotic. Paget's disease is suspected to be related to prior viral infection, but the cause remains mysterious. Complications include myelophthisic anemia, high output cardiac failure, pain secondary to nerve compression, deformities secondary to skeletal changes, and in about 1% of patients, osteosarcoma or other sarcoma, typically involving the jaw, pelvis, or femur.
An increased incidence of astrocytomas (choice A) is associated with tuberous sclerosis.
Hodgkin's lymphoma (choice B) is usually a disease of young adults, although older patients may have the lymphocyte-depleted form.
Meningiomas (choice C) are mostly benign tumors that affect adults, especially females. There may be an association with breast cancer, possibly related to high estrogen states.
Non-Hodgkin's lymphoma (choice D) is more common in AIDS and other immunodeficiency states, although the incidence in the immunocompetent is increasing.
--------------------------------------------------------------------------------3The correct answer is C. This question required that you know two pieces of information: (1) renin is secreted from the juxtaglomerular (JG) cells; and (2) the location of the JG cells in a picture that includes both the glomerulus and the juxtaglomerular apparatus. Remember that renin is responsible for converting angiotensinogen to angiotensin I, which is subsequently converted to angiotensin II in the lungs by an important enzyme appropriately called angiotensin-converting enzyme. Angiotensin II helps preserve blood pressure both by its potent vasoconstrictor properties and by its ability to stimulate aldosterone secretion from the adrenal cortex.
The label for choice A points to the glomerular basement membrane.
The label for choice B points to the epithelium of Bowman's capsule.
The label for choice D points to the macula densa cells, which are thought to sense sodium concentration in the distal convoluted tubule.
The label for choice E points to the Polkissen cells. Their function is unknown.
--------------------------------------------------------------------------------4The correct answer is B. The findings suggest disseminated intravascular coagulation (DIC), which is a feared complication of many other disorders, such as obstetrical catastrophes, metastatic cancer, massive trauma, and bacterial sepsis. The basic defect in DIC is a coagulopathy characterized by bleeding from mucosal surfaces, thrombocytopenia, prolonged PT and PTT, decreased fibrinogen level, and elevated fibrin split products. Helmet cells and schistocytes (fragmented red blood cells) are seen on peripheral blood smear.
Autoimmune hemolysis (choice A) and hereditary spherocytosis (choice C) would be characterized by spherocytes in the peripheral smear.
Macro-ovalocytes and hypersegmented neutrophils can be seen in megaloblastic anemia (choice D).
Sickle cells are seen in sickle cell anemia (choice E).
--------------------------------------------------------------------------------5The correct answer is C. The most common form of atrial septal defect is located near the foramen ovale (not to be confused with a patent foramen ovale, which is of little or no hemodynamic significance). They result from incomplete adhesion between the septum primum and the septum secundum during development.
Atrial septal defects less commonly result from failures of formation of the septum primum (choice A) and septum secundum (choice B).
Malformations of the interventricular septum (choices D and E) cause ventricular septal defects rather than atrial septal defects.
--------------------------------------------------------------------------------6The correct answer is D. Leuprolide is a GnRH analog. Given long-term in a continuous fashion, it will inhibit FSH and LH release, thereby decreasing testosterone production and exacting a chemical castration in men. It can be used in the treatment of prostate cancer, polycystic ovary syndrome, uterine fibroids, and endometriosis.
Inhibition of 5a-reductase (choice A) is the mechanism of action of finasteride. It thereby inhibits the production of dihydrotestosterone. It is used in the treatment of benign prostatic hyperplasia (BPH).
Flutamide is another drug used in the treatment of prostate cancer. It is a competitive antagonist at androgen receptors (choice B).
Since LH activates interstitial cells to secrete testosterone, a synthetic analog of LH (choice C) would not be appropriate treatment for prostatic cancer. The same goes for a testosterone analog (choice E).
Here is a brief chart that will aid you in remembering the actions of these similar sounding drugs:
Drug Action Indication
Leuprolide GnRh analog Prostate CA
Flutamide Competitive androgen antagonist Prostate CA
Finasteride 5a-reductase inhibitor BPH
Remember, "loo"prolide and "floo"tamide are both used for prostate cancer. Finasteride is used for BPH.
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7The correct answer is D. 21-hydroxylase deficiency is the most common form of congenital adrenal hyperplasia. The simple virilizing variant (without salt wasting) is most common, but with severe 21-hydroxylase deficiency, virilization and salt wasting occur. The infant described above exhibits salt wasting and hyperkalemia because aldosterone secretion is diminished by the enzyme deficiency. The hypoglycemia is due to cortisol deficiency. Because cortisol secretion is diminished in congenital adrenal hyperplasia, ACTH secretion from the anterior pituitary is increased due to loss of negative feedback inhibition. The high levels of ACTH are responsible for the adrenal hyperplasia and the increased secretion of the adrenal androgens, dehydroepiandrosterone and androstenedione, which are responsible for the virilization of the external genitalia. 17-OH progesterone is the steroid precursor just proximal to 21-hydroxylase and is also increased because of the excessive drive to the adrenal cortex by ACTH.
5-alpha-reductase deficiency (choice A) in male fetuses will produce normal differentiation of the internal reproductive tracts, but the external genitalia will be feminized. This is because testosterone needs to be converted to dihydrotestosterone (by 5-alpha-reductase) in the external genitalia and the prostate for normal differentiation into the male phenotype.
11-beta-hydroxylase deficiency (choice B) is another form of congenital adrenal hyperplasia. It is characterized by salt retention due to excessive secretion by the inner zones of the adrenal cortex of the weak mineralocorticoid, deoxycorticosterone. Again, the excessive drive to the adrenal cortex is due to increased ACTH resulting from diminished negative feedback suppression by cortisol. The adrenal also secretes excessive androgens and virilization occurs in female fetuses.
17-alpha-hydroxylase deficiency (choice C) is another from of congenital adrenal hyperplasia that is accompanied by salt retention. The high levels of ACTH drive the adrenal cortex to secrete increased amounts of deoxycorticosterone and corticosterone, both of which have weak mineralocorticoid activity. Without the ability to 17-alpha-hydroxylate progesterone or pregnenolone, steroid-secreting cells cannot produce sex steroids. When 17-alpha-hydroxylase deficiency is present in the adrenal cortex, it is also present in the gonads. Hence, whether it occurs in a male or female fetus, sex steroid production will be diminished. Female fetuses will develop normal reproductive tracts and genitalia since these structures are programmed in utero to "automatically" become female. Male fetuses, however, will have their reproductive tracts and genitalia feminized.
Complete androgen resistance (choice E) results in feminization of affected male fetuses. It is characterized by an XY genotypic male with phenotypically female external genitalia and a vagina that ends as a blind sac.
--------------------------------------------------------------------------------8The correct answer is E. Vibrio vulnificus is an extremely invasive organism, producing a septicemia in patients after eating raw shellfish, or causing wound infections, cellulitis, fasciitis, and myositis after exposure to seawater or after cleaning shellfish. Patients at high risk for septicemia include those with liver disease, congestive heart failure, diabetes mellitus, renal failure, hemochromatosis, and immunosuppression.
Citrobacter diversus (choice A) produces neonatal meningitis and can be frequently cultured from the umbilicus.
Enterotoxigenic E. coli (choice B) produces the classic traveler's diarrhea. The toxin is ingested in water and salads. The incubation period is approximately 12 hours. The diarrhea is non-inflammatory and treatment is supportive.
Providencia stuartii (choice C) is a gram-negative rod related to Proteus. It is a common cause of nosocomial bacteremia in nursing home patients with chronic catheterization.
Vibrio cholerae (choice D) produces a non-invasive, non-inflammatory, high-volume secretory diarrhea that is toxin-mediated.
--------------------------------------------------------------------------------9The correct answer is D. The disease in question is leprosy, or Hansen's disease. A key feature in the description is the fact that the organism is acid-fast. Both of the mycobacteria, M. avium-intracellulare and M. leprae are strongly acid-fast, that is they retain the carbol fuchsin dye in the face of acid-alcohol decolorization. M. leprae has a predilection for the skin and cutaneous nerves, thereby producing the symptoms of depigmentation and anesthetic cutaneous lesions. This loss of peripheral nerve function leads to many of the disfiguring features of the disease; because the patients do not have normal pain sensation, they sustain repeated injuries. In addition, the organism attacks cartilage and causes granuloma formation in the skin, leading to some of the facial disfigurement.
Bartonella henselae (choice A) is a very small, gram-negative bacterium that is closely related to the rickettsia, although it is able to be cultured on lifeless media. It is the cause of cat-scratch disease, a local, chronic lymphadenitis most commonly seen in children, and bacillary angiomatosis, a disease seen particularly in AIDS patients.
Listeria monocytogenes (choice B) is a ubiquitous microbe that causes disease in over 100 animal species. Although it is best known as an agent of meningitis in the newborn, it is a cause of multiple other diseases. A characteristic feature of these infections is the development of granulomas at the site of the infection. The organism is not acid-fast and has no particular predilection for skin or nervous tissues.
M. avium-intracellulare (choice C) causes tuberculosis-like pulmonary disease in the immunosuppressed.
Nocardia asteroides (choice E) primarily produces pulmonary infections in humans. The organism is consider to be "weakly" acid-fast, meaning that if the amount of HCl used in the decolorization step is reduced, the organisms will retain the carbolfuchsin primary stain.
--------------------------------------------------------------------------------10The correct answer is A. The cells described are the primordial eggs, which remain stopped in the diplotene stage of the first meiotic division from before birth until fertilization, a period which may be 40 or more years.
Choices B and E are incorrect because the oocytes are stopped in the first, not second meiotic division.
Choices C and D are incorrect because the cells described are oocytes and are not in mitosis.
--------------------------------------------------------------------------------11The correct answer is D. This is impetigo, which is typically seen in preschool children with poor hygiene, particularly in the summer in warm climates. The characteristic lesion has a large golden crust. Most cases are caused by Staphylococcus aureus; Streptococcus pyogenes is occasionally implicated. Impetigo is highly infectious, and mini-epidemics can occur in daycare settings. The initial treatment is typically with penicillins and topical preparations. Methicillin-resistant strains are presently rare in this setting, but can occur.
Aphthous ulcers (choice A), commonly known as "canker sores," are painful, shallow ulcers of the oral cavity.
Erysipelas (choice B) is a different type of skin infection, often caused by Streptococcus pyogenes (also sometimes others including Staphylococcus), and is characterized by large erythematous patches.
Herpes simplex I (choice C) causes tiny oral and perioral vesicles, but not large golden crusts.
Measles (choice E) causes a blotchy erythematous rash.
--------------------------------------------------------------------------------12The correct answer is C. This little boy has a Meckel's diverticulum, an ileal outpocketing typically located within 50-75 cm of the ileocecal valve. It is a congenital anomaly resulting from the persistence of the vitelline (omphalomesenteric) duct. Approximately half cause ulceration, inflammation, and gastrointestinal bleeding due to the presence of ectopic acid-secreting gastric epithelium. Pancreatic tissue may sometimes occur in these diverticula as well. Note that this is the most common type of congenital gastrointestinal anomaly.
Something else to keep in mind: A favorite question attendings ask on the wards is the rule of 2's associated with Meckel's diverticulum: it occurs in about 2% of children, occurs within approximately 2 feet of the ileocecal valve, contains 2 types of ectopic mucosa (gastric and pancreatic), and its symptoms usually occur by age 2.
All of the other answer choices have no relationship to Meckel's diverticulum.
--------------------------------------------------------------------------------13The correct answer is B. The patient has primary atypical pneumonia caused by Mycoplasma pneumoniae. This organism is fastidious and difficult to culture in the laboratory, however serodiagnosis can be most helpful. Patients typically produce one or two heterophile antibodies during the course of the infection; one agglutinates human O+ RBCs in the cold (the cold hemagglutinin) while the other causes the agglutination of a strain of Streptococcus salivarius termed strain MG (the Strep MG agglutinins).
Klebsiella pneumoniae (choice A) is readily cultured on routine laboratory media and characteristically produces pneumonia with blood clots in the sputum (red currant jelly sputum), which may be indicative of pulmonary abscess development.
Parainfluenza viruses (choice C) cause croup, which is characterized by a dry, "barking" cough. It is more of a tracheitis, bronchitis, and bronchiolitis than a pneumonitis. No heterophile antibodies are produced in these patients.
Respiratory syncytial virus (choice D) causes an atypical pneumonitis in infants. It is usually diagnosed by the observation of syncytial masses in respiratory secretions. Cold hemagglutinins and Strep MG agglutinins are absent.
Streptococcus pneumoniae (choice E) is the number one cause of pneumonia in adults. It also causes septicemia and meningitis in the elderly. The patient has a classical acute pneumonia with a productive cough, high fever with chills, leukocytosis, tachycardia, rapid respirations and other signs of serious respiratory disease. A vaccine, composed of the capsular carbohydrate of 23 serotypes of this organism, is routinely given to individuals over the age of 60, as well as to individuals with splenic abnormalities (e.g., sickle cell disease) who are at increased risk for pneumococcal sepsis.
--------------------------------------------------------------------------------14The correct answer is F. Aneurysm of the posterior communicating artery is the second most common aneurysm of the circle of Willis (anterior communicating artery is most common) and can result in third cranial nerve palsy (paralysis). The oculomotor nerve (CN III) innervates the levator palpebrae muscle. CN III paralysis would therefore result in ptosis (drooping of the upper eyelid). CN III also innervates all of the extraocular muscles, except for the superior oblique (CN IV) and the lateral rectus muscles (CNVI). Thus, CN III palsy would result in unopposed action of the superior oblique and lateral rectus muscles, causing the affected eye to look down and out. CN III also supplies parasympathetic innervation to the sphincter muscle of the iris (which constricts the pupil) and to the ciliary muscle. Interruption of this pathway leads to a dilated and fixed pupil and to paralysis of accommodation.
Note that this question teaches you about another Boards-favorite pathology: subarachnoid hemorrhage (SAH). (In this case, it was due to rupture of a posterior communicating artery aneurysm). A classic clue to the diagnosis is a patient presenting with "the worst headache of their life." When you are presented a case of sudden severe headache, SAH should rank highly on your differential diagnosis list.
The anterior cerebral artery (choice A) supplies the medial surface of the cerebral hemisphere, from the frontal pole to the parieto-occipital sulcus. Occlusion may produce hypesthesia and paresis of the contralateral lower extremity.
The anterior choroidal artery (choice B) arises from the internal carotid artery and is not part of the circle of Willis. It perfuses the lateral ventricular choroid plexus, the hippocampus, parts of the globus pallidus and posterior limb of the internal capsule.
The anterior communicating artery (choice C) connects the two anterior cerebral arteries. It is the most common site of aneurysm in the circle of Willis and may cause aphasia, abulia (impaired initiative), and hemiparesis.
The middle cerebral artery (choice D) supplies the lateral convexity of the cerebral hemisphere, including Broca's and Wernicke's speech areas and the face and arm areas of the motor and sensory cortices. It also gives rise to the lateral striate arteries, which supply the internal capsule, caudate, putamen, and globus pallidus. The middle cerebral artery is the most common site of stroke.
The ophthalmic artery (choice E) enters the orbit with the optic nerve (CN II) and gives rise to the central artery of the retina. Occlusion results in blindness.
The posterior inferior cerebellar artery (choice G) supplies the dorsolateral medulla and the inferior surface of the cerebellar vermis. Occlusion may result in Wallenberg's syndrome: cerebellar ataxia, hypotonia, loss of pain and temperature sensation of the ipsilateral face, absence of corneal reflex ipsilaterally, contralateral loss of pain and temperature sensation in the limbs and trunk, nystagmus, ipsilateral Horner's syndrome, dysphagia, and dysphonia.
--------------------------------------------------------------------------------15The correct answer is C. A variety of glycogen storage diseases exist, corresponding to defects in different enzymes in glycogen metabolism; most of these involve the liver. McArdle's disease (Type V glycogen storage disease), due to a defect in muscle phosphorylase, is restricted to skeletal muscle. The presentation described in the question stem is typical. Many affected individuals also experience myoglobinuria. Definitive diagnosis is based on demonstration of myophosphorylase deficiency.
Hartnup's disease (choice A) is a disorder of amino acid transport.
Krabbe's disease (choice B) is a lysosomal storage disease.
Niemann-Pick disease (choice D) is a lysosomal storage disease.
Von Gierke's disease (choice E) is a glycogen storage disease with prominent involvement of liver, intestine, and kidney.
--------------------------------------------------------------------------------16The correct answer is D. The disease is Down syndrome (trisomy 21). In addition to mental retardation and the characteristic physical findings described in the question stem, duodenal atresia is fairly common, as evidenced by the "double bubble" sign on x-ray. These children are also likely to have various cardiac anomalies; endocardial cushion defect is the most common.
Atrial septal defect (choice A) is one of the most common genetic defects in the general population, but is less common than endocardial cushion defect in patients with Down syndrome.
Berry aneurysms (choice B), also known as saccular aneurysms, are typically located in the circle of Willis on the ventral surface of the brain. They occur more frequently in patients with adult polycystic disease. Rupture can produce subarachnoid hemorrhage.
Coarctation of the aorta (choice C) occurs more commonly in females with a 45, XO genotype (Turner syndrome).
Tetralogy of Fallot (choice E) is the most common cause of early cyanosis, consisting of a ventricular septal defect, right ventricular outflow tract obstruction, an overriding aorta, and right ventricular hypertrophy.
--------------------------------------------------------------------------------17The correct answer is E. All of the laboratory data in this pregnant woman are normal, hence no further study is necessary. In a normal pregnancy, both the plasma volume and RBC mass are increased with a greater increase in the plasma volume than RBC mass (2:1 ratio). This has a dilutional effect on many laboratory tests.
Increasing plasma volume in pregnancy increases the creatinine clearance (choice A) due to the expected elevation in the glomerular filtration rate (GFR). The reference intervals for serum blood urea nitrogen and creatinine are lower than normal, due to the dilutional effect of increased plasma volume and increased clearance of both analytes in the urine caused by the rise in the GFR.
The threshold for glucose is reduced in pregnancy, so patients can have a positive dipstick test for glucose in the presence of a normal serum glucose. Therefore, an oral glucose tolerance test (choice B) is not indicated.
The hemoglobin (Hb) concentration in pregnancy is normally decreased because of the dilutional effect of increased plasma volume. Since the Hb is normal (for a pregnant woman) in this patient, a serum ferritin (choice C) to rule out iron deficiency is unnecessary. Furthermore, iron deficiency is usually associated with a low MCV (microcytic anemia), and her MCV is normal.
Although sickle disease is the most common genetic hemoglobinopathy among African Americans, the patient is not anemic, so there is no reason to order a sickle cell preparation (choice D).
--------------------------------------------------------------------------------18The correct answer is D. The endometrial phase with small glands is the proliferative phase; the one with large glands with secretory cells is the secretory phase. Estrogen (choice C) is necessary for both phases, but it is the addition of progesterone (choice D), secreted by the corpus luteum after the Graafian follicle ruptures, that triggers the switch from proliferative to secretory endometrium.
Glucocorticoids (choice B) and the mineralocorticoid aldosterone (choice A) are secreted by the adrenal glands. They do not produce the endometrial changes described.
Thyroxine (choice E) is secreted by the thyroid gland, and is unrelated to the observed morphologic changes in the endometrium.
--------------------------------------------------------------------------------19The correct answer is D. The distinctive cell balls described are broken-off papillary clusters, and are considered pathognomic for papillary carcinoma of the thyroid. This is the most common form of thyroid carcinoma. It tends to present in the 3rd to 5th decade and shows a modest female predominance. Despite its propensity for local lymphatic intrusion (which may cause multifocality of tumor in the thyroid or cervical lymph node metastases), the tumor generally has an excellent prognosis with 90% 20-year survival.
Follicular carcinoma (choice A) is characterized by follicular cells and colloid on aspiration, and cannot be reliably distinguished from thyroid adenoma.
Distinctive features of Hashimoto's disease (choice B) on aspiration are lymphocytes, plasma cells, and macrophages.
The most distinctive feature of medullary carcinoma (choice C) on aspiration is the presence of amyloid.
Thyroid adenoma (choice E) shows follicular cells and colloid on aspiration, and cannot be reliably distinguished from follicular carcinoma.
--------------------------------------------------------------------------------20The correct answer is D. This is a straightforward question relating to the definition of Nissl bodies. Rough endoplasmic reticulum present in neurons are called Nissl bodies. They stain intensely with basic dyes and are found in the cell body and proximal dendrites, but not in the axon hillock or axon.
--------------------------------------------------------------------------------21The correct answer is A. Sawtooth waves appearing in bursts are associated with REM sleep.
Stage 1 (choice B) is associated with 4-7 Hz theta waves.
Stage 2 (choice C) is associated with 12-14 Hz sleep spindles and K-complexes.
Stage 3 (choice D) is associated with < 4 Hz, high-amplitude delta waves.
Stage 4 (choice E) is characterized by an EEG composed of about 50% delta waves.
Note that beta waves (15-18 Hz) occur during periods of more intense mental activity while awake. Alpha waves (8-12 Hz) occur during awake, relaxed states. REM is the stage of sleep that most resembles the awake state on the EEG.
--------------------------------------------------------------------------------22The correct answer is E. The disease is poliomyelitis. Most infections with poliovirus cause only the influenza-like symptoms, but a small percentage progress to paralytic poliomyelitis. The most common causes of death are aspiration and airway obstruction as a result of bulbar paralysis and paralysis of respiratory muscles. Arrhythmias can also be life-threatening.
Acute renal failure (choice A) is usually not seen in poliomyelitis, although the bladder may become paralyzed.
Bowel paralysis (choice B) can be seen, but is not usually life-threatening.
Fulminant liver failure (choice C) is not a feature of poliomyelitis.
Gastrointestinal bleeding (choice D) can be seen in poliomyelitis, but is not usually life-threatening.
--------------------------------------------------------------------------------23The correct answer is D. The ratio of cells in bone marrow developing along myeloid lines to cells developing along erythroid lines is 3:1. An alternative way to remember the normal marrow composition is that it typically contains about 60% granulocytes and their precursors; 20% erythroid precursors; 10% lymphocytes, monocytes, and their precursors; and 10% unidentified or disintegrating cells. These numbers are worth remembering, because shifts away from normal values may be a subtle clue to marrow abnormalities.
--------------------------------------------------------------------------------24The correct answer is E. An obese adult with glucosuria, but not ketonuria, likely has type 2 diabetes mellitus. Type 2 diabetes is characterized by insulin resistance resulting in hyperglycemia and increased serum osmolarity. The dehydration associated with osmotic diuresis makes the hyperosmolarity worse. As the osmolarity increases above 330 mOsm/L, the osmotic loss of water from neurons is sufficient to produce coma. In nonketotic, hyperosmolar coma, blood glucose values can range from 800 to 2,400 mg/dL and produce serum osmolarities of 330-440 mOsm/L.
Since type 2 diabetes is due to insulin resistance, plasma levels of insulin are usually normal to increased. Because b cells secrete insulin and C-peptide in a 1:1 ratio, plasma concentration of C-peptide would also be normal to increased (not decreased, choice A) in type 2 diabetes.
Even small amounts of insulin are sufficient to prevent ketosis. In type 2 diabetes there is enough insulin effect to prevent significant lipolysis and subsequent formation of excess ketone bodies. Hence, acidosis (choice B) is not typically associated with this disorder. Since b-hydroxybutyrate is a ketone body, its concentration in plasma is not likely to be increased (choice D).
While there is a significant autoimmune component to type 1 diabetes, type 2 diabetes is not associated with increased circulating antibodies (choice C) against b cell proteins such as glutamic acid decarboxylase.
--------------------------------------------------------------------------------25The correct answer is B. Neuromuscular development is sufficient to allow fetal movement in the eighth week of life. Other features of week 8 include the first appearance of a thin skin, a head as large as the rest of the body, forward-looking eyes, appearance of digits on the hands and feet, appearance of testes and ovaries (but not distinguishable external genitalia), and a crown-rump length of approximately 30 mm. By the end of the eighth week, nearly all adult structures have at least begun to develop, and the fetus "looks like a baby".
--------------------------------------------------------------------------------26The correct answer is A. The Rb gene is an example of a tumor suppressor gene. Tumor suppressor genes encode proteins that downregulate cell growth; consequently, their deletion leads to the development of cells with a growth advantage over normal cells. Even if you know nothing about the Rb protein, choice A is still the only logical answer because it is the only example of a protein that, if absent, would favor cell growth. The Rb protein binds to transcription factors in the nucleus, preventing cells from progressing from the S1 to M stages of the cell cycle. Children born with a 13q14 deletion have only one chromosome encoding Rb; therefore only a single "hit " is required to completely knock out Rb production and lead to the development of retinoblastoma. All of the incorrect choices are proteins encoded by oncogenes, rather than tumor suppressor genes. Oncogenes favor tumorigenesis through overexpression, not deletion.
Growth factors (choice B) are oncoproteins that are produced by tumors and have a positive feedback effect. Examples of growth factors are PDGF and fibroblast growth factor; the oncogenes encoding them are sis and hst-1, respectively.
The prototypical growth factor-binding protein (choice C) is ras, which is mutated in a large variety of cancers. Ras normally functions as an activator of protein kinases that regulate cell growth. Overactivity of the ras protein is highly mitogenic.
Growth factor receptors (choice D) are either expressed as mutant forms or overexpressed in tumors, leading to upregulation of growth. An example of a growth factor receptor oncogene is erb-B2, present in some breast cancers.
Transcription activators (choice E) are DNA-binding proteins that promote DNA transcription. Amplification of these oncogenes causes cancer by promoting the transcription of growth-related genes.
--------------------------------------------------------------------------------27The correct answer is A. The obturator nerve innervates the muscles of the medial compartment of the thigh. These include the adductor longus, adductor brevis, adductor magnus, and gracilis muscles. The adductor magnus is also innervated by the tibial nerve.
The biceps femoris (choice B) is in the posterior compartment of the thigh. The long head of the biceps femoris is innervated by the tibial portion of the sciatic nerve, and the short head of the biceps femoris is innervated by the common peroneal portion of the sciatic nerve.
The rectus femoris (choice C) and vastus medialis (choice E) are two of the four heads of the quadriceps femoris muscle. All four heads of the quadriceps femoris muscle are in the anterior compartment of the thigh, and are innervated by the femoral nerve.
The sartorius muscle (choice D) is in the anterior compartment of the thigh, and is innervated by the femoral nerve.
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28The correct answer is A. The patient has Burkitt's lymphoma. This type of lymphoma is a high-grade B-cell lymphoma that occurs in endemic form in Africa (it is the most common neoplasm in children in an equatorial belt that includes Africa and New Guinea) and sporadically in the United States and Europe. The sporadic form is often in an abdominal site and occurs in young adults. The African form of Burkitt's lymphoma has been strongly associated with antibodies directed against Epstein-Barr virus; the association is weaker in sporadic cases. A characteristic translocation, t(8;14) (q24.l3;q32.33) has been described.
Hepatitis B (choice B) is associated with hepatocellular carcinoma. t(9;22) is the Philadelphia chromosome, which is seen in some cases of CML and AML.
Herpesvirus (choice C) does not have a strong tumor association, although a link to cervical cancer has intermittently been proposed. CD5 is a marker seen in small lymphocytic and mantle cell lymphomas.
HIV (choice D) is linked to Kaposi's sarcoma (and AIDS). Some patients also develop primary lymphomas (not usually Burkitt's). CD4 is a marker for helper T cells and some T cell lymphomas.
Human papillomavirus (choice E) is linked with common warts, genital condylomata, and genital cancers. t(2;5) is linked to anaplastic large cell lymphoma.
--------------------------------------------------------------------------------29The correct answer is E. The patient is presenting with hypertension and signs and symptoms of benign prostatic hyperplasia (BPH). The essential diagnostic characteristics of BPH include a decrease in the force and caliber of the urinary stream, nocturia, high post-void residual volume, urinary retention, and azotemia. Terazosi

usmle-mcq's-9

2008-03-17T08:24:00.001-07:00

<1>A 61-year-old woman with leukemia abruptly develops an intensely
itchy rash. Physical examination demonstrates multiple erythematous patches
of the distal arms and legs, some of which involve the palms and soles.
Some of the patches show central clearing with surrounding erythematous
rings. Which of the following is the most likely diagnosis?
A. Erythema migrans chronicum
B. Erythema multiforme
C. Kaposi's sarcoma
D. Psoriasis
E. Urticaria
Answer
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<2>A 52-year-old woman presents to her physician for a check-up. She is
recovering from a wrist fracture after a fall. Dual energy x-ray
absorptiometry of the hip had shown her to have osteoporosis. She
became menopausal at age 50 and did not begin hormone replacement
therapy because of a strong family history of breast cancer. She
now fears a future hip fracture and would like to begin a bone
loss prevention regime.Which of the following pharmaceutical
agents is most appropriate for this patient?
A. Calcitonin nasal spray
B. Oral conjugated estrogen
C. Raloxifene
D. Tamoxifen
E. Transdermal estradiol
Answer
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<3>A fracture of the humerus neck damages a nerve running around the
humeral neck. After the fracture heals, the patient notices a marked
decrease in his ability to raise his arm over his head. The denervated
muscle arises from which of the following?
A. Acromion alone
B. Clavicle and acromion
C. Clavicle and coracoid
D. Coracoid alone
E. Coracoid and acromion
Answer
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<4>A patient is admitted to a psychiatric hospital after having been picked
up by the police for making inappropriate sexual advances. A detailed
psychiatric interview demonstrates deficits in memory, insight,
judgement, personal appearance, and social behavior. The patient
is witnessed experiencing a possible epileptic seizure. Over a
period of several years, motor findings also develop, including
relaxed, but expressionless facies, tremor, dysarthria,
and pupillary abnormalities. Which of the following tests performed on his cerebrospinal fluid would most likely be diagnostic?
A. CSF glucose
B. FTA-ABS
C. Gram's stain
D. Lymphocyte count
E. Neutrophil count
Answer
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5>A 29-year-old single man seeks psychiatric treatment to help him deal
with difficulties in his personal life. Although the man is a successful
computer programmer, he feels unsatisfied with his interpersonal
relationships. He reports being attracted to several of his female
coworkers, but is "too shy" to talk to them about anything other
than superficial subjects such as the weather. He would like to ask
one of the women out on a date, but is afraid of being rejected.
Which of the following diagnoses is most appropriate?
A. Avoidant personality disorder
B. Borderline personality disorder
C. Dependent personality disorder
D. Narcissistic personality disorder
E. Schizotypal personality disorder
Answer
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<6>A 3-month-old infant presents with a 3-day history of fever, cough,
and poor feeding. On examination, the baby appears ill and has a
temperature of 102 F and a respiratory rate of 32. A chest x-ray
film shows bilateral patchy infiltrates in the lungs. Which of
the following is the most likely etiologic agent?
A. Coronavirus
B. Influenza type A
C. Parainfluenza type 1
D. Respiratory syncytial virus
E. Rhinovirus
Answer
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<7>A 35-year-old male presents to the urologist for an infertility
evaluation. A biopsy of his testis is performed to check sperm
production and maturation. A microscopic section reveals only
a few germ cells near the basal lamina in the seminiferous
tubule. Which of the following cells is the germ cell closest
to the basal lamina in the seminiferous tubule?
A. Primary spermatocyte
B. Secondary spermatocyte
C. Spermatid
D. Spermatogonia
E. Spermatozoa
Answer
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<8>A 30-year-old otherwise healthy woman presents to her physician
with complaints of fatigue and dyspnea. Physical examination reveals
normal breath sounds and the presence of third and fourth heart sounds.
Chest x-ray shows clear lung fields but right ventricular enlargement,
main pulmonary artery enlargement, and "pruning" of the peripheral
vasculature. Electrocardiogram shows right axis deviation and right
ventricular hypertrophy. Left ventricular function appears normal
on echocardiography. Serologic studies show antinuclear antibodies.
Which of the following pathological findings would this patient
also show, either at autopsy or if an appropriate biopsy was taken?
A. Mural thrombus of the right atrium
B. Necrosis and scarring of the left ventricle
C. Plexogenic pulmonary vasculopathy
D. Pulmonary artery stenosis
E. Severe pulmonary fibrosis
Answer
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<9>During an abdominal surgical procedure, the surgeon wishes to locate
the ureter in order to ensure that it is not injured. The ureter may be
found immediately anterior to the origin of the
A. common iliac artery
B. external iliac artery
C. internal iliac artery
D. gonadal artery
E. renal artery
Answer
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<10>A patient with mild congestive heart failure is treated with high-dose
furosemide and diureses 25 pounds of fluid. A complete blood count (CBC)
taken before the diuresis shows an RBC count of 4 million/mm3; a CBC
taken after diuresis shows a RBC count of 7 million/mm3. Which of the
following is the most likely explanation?
A. Cyanotic heart disease
B. Increased erythropoietin
C. Polycythemia vera
D. Relative polycythemia
E. Renal cell carcinoma
Answer
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<11>A newborn male child is noted to have hypospadias. A complete
evaluation determines that the child has no other genitourinary
anomalies. Nonetheless, hypospadias repair will be performed to
prevent which of the following possible sequelae?
A. Bladder exstrophy
B. Hydrocele
C. Phimosis
D. Urachal cysts
E. Urinary tract infection
Answer
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<12>During the passage of an intravenous catheter, numerous endothelial
cells are dislodged from the lining of the popliteal vein. What substance
allows platelet adhesion to the exposed collagen fibers?
A. Factor VIII
B. Factor IX
C. Fibronectin
D. Tissue factor
E. Von Willebrand factor
Answer
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<13>A 57-year-old man presents to the emergency department with a
nosebleed for the past 2 hours. The patient received a prosthetic
heart valve 5 months ago and is currently taking warfarin (7.5 mg per day)
and oral antibiotics. Laboratory evaluation reveals
an INR (international normalized ratio, the ratio of
patient to normal prothrombin times) of 6.4. Which of
the following antibiotics is the patient most likely taking?
A. Ampicillin
B. Cephalexin
C. Nitrofurantoin
D. Norfloxacin
E. Phenazopyridine
Answer
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<14>A 47-year-old woman presents with complaints of nervousness and
increased sensitivity to hot weather. She is diagnosed with
hyperthyroidism and prescribed propylthiouracil. What is
the principal mechanism by which this drug acts?
A. Decreasing the efficacy of TSH binding to the thyroid TSH receptor
B. Decreasing the rate of proteolysis of thyroglobulin
C. Increasing the amount of 3,3',5'-triiodothyronine (reverse T3; rT3)
D. Inhibiting deiodination of thyroxine (T4)
E. Inhibiting the uptake of iodide into the thyroid gland
Answer
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<15>Which of the following neurotransmitters is most important for the
induction of REMsleep?
A. Acetylcholine
B. Dopamine
C. Epinephrine
D. Norepinephrine
E. Serotonin
Answer
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<16>A 37-year-old woman presents with 3 days of progressive joint pain
in her ankles, knees, and wrists. She had three similar episodes
over the past several years. On examination, she has a temperature
of 38.7 C, her blood pressure is 110/70 mm Hg, and her heart rate
is 90/min. She has a diffuse petechial rash over her trunk and extensor
surfaces. Her ankles and knees are swollen, red, and tender with
decreased range of motion, and there is tenderness over the tendon
sheaths of her hands and forearms. Blood cultures are negative.
Aspiration of joint fluid reveals a white cell count of
22,000/mm3 with no visible organisms, but culture on
chocolate agar is positive. Which of the following
is an attribute of the causative organism that allows
it to produce recurrent infections?
A. It is an intracellular pathogen
B. It is resistant to ceftriaxone
C. It is resistant to complement-mediated lysis
D. Its capsule is not immunogenic
E. Its pili undergo antigenic and phase variation
Answer
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<17>The data presented below compares the results of a diagnostic
test in the presence and absence of a disease.
Disease present Disease absent
Positive test 40 5
Negative test 10 95
Total 50 100
The specificity of the test is
A. 0.05
B. 0.40
C. 0.80
D. 0.90
E. 0.95
Answer
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<18>Blood stored in a blood bank tends, with time, to become relatively depleted of 2,3-diphosphoglycerate. What effect does this have on the hemoglobin-oxygen dissociation curve?
A. Shifts the curve to the left, so that the hemoglobin has a decreased oxygen affinity
B. Shifts the curve to the left, so that the hemoglobin has an increased oxygen affinity
C. Shifts the curve to the right, so that the hemoglobin has a decreased oxygen affinity
D. Shifts the curve to the right, so that the hemoglobin has an increased oxygen affinity
E. Does not change the dissociation curve
Answer
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<19>A psychotic, indigent man with a history of multisubstance
abuse has been involuntarily hospitalized for 1 week. Because of
persistent diarrhea, stools are sent for ova and parasites,
revealing numerous granular, spherical, thin-walled cysts
measuring 10-20 mm in diameter. Trichrome stains show up to
four nuclei in most of the cysts. These finding are consistent
with an infection by which of the following organisms?
A. Cryptosporidium parvum
B. Dientamoeba fragilis
C. Entamoeba histolytica
D. Giardia lamblia
E. Isospora belli
Answer
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<20>A child who understands that the volume of a liquid poured out of
a narrow glass remains the same when poured into a wider glass is at
which of Piaget's stages of intellectual development?
A. Concrete operations
B. Formal operations
C. Preoperational
D. Sensorimotor
Answer
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<21>A 4-year-old girl is brought to a specialty clinic by her foster parents because of a limp in her right leg and a serum alkaline phosphatase (ALP) that is 10 times the adult upper limit of normal for the test. The child is withdrawn and clinging to her foster mother. Physical examination is remarkable for a blue-green discoloration of the skin overlying a tender, 3-cm mass on the anterior portion of the right mid-thigh. An x-ray of the right thigh reveals a dense mass within the femur that extends into the surrounding tissue. Which of the following best describes the increased alkaline phosphatase and physical findings in this case?
A. ALP is abnormal for her age and the bone lesion represents an area of aseptic necrosis
B. ALP is abnormal for her age and the bone lesion represents repair of a femoral fracture
C. ALP is abnormal for her age and is unrelated to the bone lesion
D. ALP is normal for her age and the bone lesion is an osteogenic sarcoma
E. ALP is normal for her age and is unrelated to the bone lesion
Answer
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<22>Which of the following drugs antagonizes both the vascular and cardiac
actions of norepinephrine?
A. Atenolol
B. Esmolol
C. Labetalol
D. Metaproterenol
E. Prazosin
Answer
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<23>During surgery to treat an ischioanal abscess, the inferior rectal
nerve is damaged. This nerve is a direct branch of which of the following
nerves?
A. Inferior gluteal nerve
B. Pelvic splanchnic nerve
C. Pudendal nerve
D. Sciatic nerve
E. Superior gluteal nerve
Answer
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<24>A 15-year-old girl is evaluated for failure to begin menstruation.
Physical examination demonstrates short stature and a webbed neck.
Chromosomal analysis demonstrates a lack of one X chromosome. This
patient should be specifically evaluated for which of the following
cardiovascular anomalies?
A. Coarctation of the aorta
B. Dextrocardia
C. Ostium primum septal defect
D. Pulmonary stenosis
E. Tetralogy of Fallot
Answer
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<25>A baby is born with a testicular mass. Histologic sections made of the
homogeneous yellow-white mass after its removal demonstrate
epithelial-lined spaces that have flattened-to-cuboidal epithelial
cells with vacuolated cytoplasm containing eosinophilic, hyaline-like
globules. Scattered structures resembling primitive glomeruli
(endodermal sinuses) are also seen. If appropriate
immunohistochemical stains are performed, the eosinophilic
cytoplasmic globules would most likely contain which of the following?
A. Alpha-fetoprotein
B. Estrogen receptors
C. Human chorionic gonadotropin
D. Human papilloma virus
E. Melanin
Answer
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<26>A surgeon wishes to perform a splenectomy on a patient who has
been in an automobile accident. Before removing the spleen, the
splenic artery and splenic vein are ligated. Within which of the
following peritoneal structures are the splenic artery and vein found?
A. Gastrocolic ligament
B. Gastrosplenic ligament
C. Lesser omentum
D. Splenorenal ligament
Answer
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<27>A 65-year-old woman with a long-standing disease has bone marrow
fibrosis and increased bone remodeling, with bone resorption exceeding
bone formation. She has a history of passing calcium-oxalate kidney
stones. Which of the following lab result profiles would be expected
in the serum of this patient?
Calcium Phosphate PTH
A. decreased decreased increased
B. decreased increased decreased
C. decreased increased increased
D. increased decreased increased
E. increased increased increased
Answer
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<28>Upon examination of a newborn male, a cystic structure is found
in the scrotum. It is determined that there is a hydrocele of the
spermatic cord. Which of the following is the most likely etiology
of this finding?
A. Communication between the epididymis and the tunica vaginalis
B. Failure of the processus vaginalis to form
C. Failure of the processus vaginalis to fuse
D. Incomplete fusion of the processus vaginalis
E. Varicosities of the spermatic vein
Answer
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<29>A Brazilian immigrant is hired at a meat-packing plant, and undergoes
an employment physical. Chest x-ray demonstrates a patchy, bilateral
pneumonia and a lung mass, and he is referred to a specialist. Biopsy
of the mass demonstrates fungal organisms with a few very distinctive
"pilot's wheel" yeast forms. Which of the following is the most likely
diagnosis?
A. Blastomycosis
B. Coccidioidomycosis
C. Histoplasmosis
D. Paracoccidioidomycosis
E. Sporotrichosis
Answer
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<30>A 34-year-old female is brought to the emergency room with severe
muscle cramps and carpopedal spasms. The patient was noted to be extremely
irritable and was complaining of tingling around the mouth and in the hands
and feet. A few hours later, laboratory examination reveals
sodium 140 mEq/L, potassium 4.2 mEq/L, chloride 101 mEq/L,
calcium 6.4 mg/dL, phosphate 5.1 mg/dL,
magnesium 2.4 (normal 1.8-3.8 mg/dL) and alkaline phosphatase 67 U/L. A CT scan of the head shows basal ganglia calcifications. Prolonged QT intervals and T wave abnormalities are noted on electrocardiogram. The history is pertinent for a thyroidectomy two months prior to admission. Which of the following conclusions is most consistent with these data?
A. An increase in dietary vitamin D is warrante
B. Hepatocytes have a low 25-hydroxylase activity
C. Intestinal cells are underexpressing calcium transporter genes
D. Isolated cells from the kidney have high 1-hydroxylase activity
E. The levels of 1,25-dihydroxy vitamin D are normal
Answer
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<31>A 48-year-old man presents to his physician with complaints of dizziness
and fatigue. Physical examination reveals a blood pressure of 130/50 mm Hg
and a heart rate of 100 beats per minute. On examination, the physician
notes a large scar on the patient's abdomen. The man states that he was
severely injured in an automobile accident several years ago, and required
abdominal surgery at that time. Which of the following is the most likely
diagnosis?
A. Arteriovenous fistula
B. Cardiac tamponade
C. Heart failure
D. Hypovolemia
E. Shock
Answer
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<32>A renal pathologist examining the day's kidney biopsies notes that one
biopsy shows amorphous red nodules within the glomerular mesangium in
hematoxylin and eosin stained material. Congo red stain of the biopsy
demonstrates apple-green birefringence of these nodules. These nodules
are most likely to be related to which of the following?
A. Acute urinary tract infection
B. Diabetes mellitus
C. Sarcoidosis
D. Systemic lupus erythematosus
E. Tuberculosis
Answer
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<33>A patient goes to his family doctor complaining of persistent and
severe headaches. His physician diagnoses migraine headaches and prescribes
sumatriptan. What is the mechanism of action of this drug?
A. Dopamine1 agonist
B. GABAB antagonist
C. Muscarinic3 antagonist
D. Non-selective beta antagonist
E. Serotonin1D agonist
Answer
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<34>A 60-year-old man presents to his physician after a routine screening
test indicates hyperlipidemia. Physical examination reveals raised,
irregular, yellow papules in the skin of the soft tissues below the eyes.
Biopsy of these lesions would most likely show which of the following?
A. Benign nevus cells
B. Malignant nevus cells
C. Microscopic blisters
D. Munro microabscesses
E. Multinucleated giant cells
Answer
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<35> Trisomy 21 Normal karyotype
Positive test 100 50
Negative test 100 250
An experimental diagnostic test is developed to noninvasively detect the
presence of trisomy 21, Down's syndrome. The test is administered to a
group of 500 women considered to be at risk for a Down's fetus based on
blood tests. The results of this test are shown above. What is the
sensitivity of this new test?
A. 40%
B. 50%
C. 67%
D. 71%
E. 83%
Answer
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<36>An autopsy is performed on a 60-year-old man who developed progressive
dementia, parkinsonism, and visual hallucinations beginning 5 years prior
to death. Histopathologic examination reveals numerous eosinophilic
intracytoplasmic inclusions within neurons of substantia nigra, limbic
cortex, and basal nucleus of Meynert. These inclusions are immunoreactive
for ubiquitin. Which of the following is the most likely postmortem
diagnosis?
A. Alzheimer disease
B. Amyotrophic lateral sclerosis (ALS)
C. Diffuse Lewy body disease (dementia with Lewy bodies)
D. Parkinson disease
E. Pick disease
Answer
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<37>A 60-year-old factory worker reports to his physician that he can no
longer push heavy boxes across the floor. Upon examination it is noted
that the patient elevates the right shoulder when attempting shoulder
flexion, but shoulder abduction is not impaired. The medial border of
the right scapula is very prominent. Which of the following nerves
innervates the affected muscle?
A. Long thoracic nerve
B. Lower subscapular nerve
C. Musculocutaneous nerve
D. Suprascapular nerve
E. Upper subscapular nerve
Answer
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<38>The American Diabetes Association (ADA) recently lowered the cutoff
value for fasting glucose used in diagnosing diabetes mellitus from
140 mg/dL to 126 mg/dL. This reference interval change would be expected
to produce which of the following alterations?
A. Decrease the test's sensitivity
B. Increase the test's false negative rate
C. Increase the test's negative predictive value
D. Increase the test's positive predictive value
E. Increase the test's specificity
Answer
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<39>An emergency room physician examines a patient who has fallen from a
motorcycle and injured his shoulder. The clinician notices a loss of the
normal contour of the shoulder and a abnormal-appearing depression below
the acromion. Which of the following injuries did the patient most likely
sustain?
A. Avulsion of the coronoid process
B. Dislocated shoulder joint
C. Fracture of the mid shaft of the humerus
D. Fracture of the surgical neck of the humerus
E. Laceration of the axillary branch of the posterior cord
Answer
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<40>A 7-month-old child with failure to thrive is found to have a hemoglobin
of 4.4 g/dL. The peripheral smear shows very small red cells with marked
pallor. It is determined that the child has very low levels of
hemoglobin A, with elevated fractions of hemoglobin A2 and hemoglobin F.
Which of the following underlying mechanisms is most likely related to
the observed findings?
A. Amino acid substitution on b globin
B. Antibody against fetal blood cells
C. Cytoskeletal protein defect
D. Insufficient production of b globin
E. Iron deficiency
Answer
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<41>During a routine pelvic examination, a 20-year-old woman is found to
have an enlarged uterus. Ultrasound studies demonstrate a multiloculated
cystic structure within the uterine cavity, but no baby is identified.
This mass is removed with dilation and curettage of the uterus, and
placental-like tissue is observed during pathologic examination.
Which of the following tumor markers would be most useful in
establishing that residual tumor does not remain in the uterus?
A. b-hCG
B. Bombesin
C. CEA
D. PSA
E. S-100
Answer
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<42>On physical examination of a 7-year-old boy, the child's upper body
appears much more developed than his lower body. Blood pressure in the
upper extremities exceeds that of the lower extremities. On cardiac
examination, there is a midsystolic murmur over the anterior chest
and back. The child's lower extremities are cold, and femoral pulses
are absent. The part of the vascular system that is affected in this
disorder is derived from which of the following embryologic
structures?
A. Bulbus cordis
B. Ductus arteriosus
C. Left horn of sinus venosus
D. Right common cardinal vein
E. Right horn of sinus venosus
F. Third, fourth, and sixth aortic arches
Answer
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<43>A 42-year-old obese woman experiences episodic abdominal pain.
She notes that the pain increases after the ingestion of a fatty meal.
The action of which of the following hormones is responsible for the
postprandial intensification of her symptoms?
A. Cholecystokinin
B. Gastrin
C. Pepsin
D. Secretin
E. Somatostatin
Answer
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<44>A 42-year-old man was in an automobile accident and suffered severe
pelvic trauma. The bulb of the penis and the urethra were torn from the
inferior surface of the urogenital diaphragm. This has allowed urine to
extravasate from the urethra. Into which of the following regions will
the urine flow?
A. Deep perineal space
B. Ischioanal space
C. Rectovesical pouch
D. Retroperitoneal space
E. Superficial perineal space
Answer
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<45>Karyotypic analysis of a spontaneously aborted fetus demonstrates
trisomy of one of the chromosomes. Which chromosome is most likely to
be affected?
A. 8
B. 13
C. 16
D. 18
E. 21
Answer
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<46>At which of the following locations might a penetrating wound to the
heart damage the AV node?
A. Apex of the heart
B. Interatrial septum
C. Interventricular septum
D. Wall of the right atrium
E. Wall of the left atrium
Answer
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<47>A 9-month-old infant is brought to the Health Department to receive
the second dose of OPV (oral polio vaccine) 2 weeks after the first
vaccination. The child has mild diarrhea, so the decision is made to
defer further immunizations. Bacteriologic examination of a stool culture
is unremarkable; however, a small, single-stranded, positive RNA virus is
isolated from the specimen. This same agent was isolated from sewage
effluent the preceding week. The viral isolate was not inactivated by
ether. Which of the following viruses was most likely isolated?
A. Adenovirus
B. Hepatitis C
C. Parvovirus B19
D. Poliovirus
E. Rotavirus
Answer
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<48> The photomicrograph shows a section of synovium from the knee joint
of a patient with rheumatoid arthritis (RA). Which of the following are
the most abundant cells in the inflammatory infiltrate?
A. Eosinophils
B. Langhans type giant cells
C. Lymphocytes and plasma cells
D. Neutrophils
E. Type A and B synovial cells
Answer

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<49>A 54-year-old African-American female patient undergoes a routine
insurance physical examination. Chest x-ray reveals bilateral hilar
masses. Biopsy of the masses shows granulomata, but acid-fast and
fungal stains are negative for organisms. Which of the following
diseases should be suspected?
A. Caroli's disease
B. Raynaud's disease
C. Sarcoidosis
D. Scleroderma
E. Systemic lupus erythematosus
Answer
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<50>A neuroscientist discovers a way to selectively label neural crest
cells in a developing laboratory animal. After birth, he sacrifices the
animal and examines the tissue to search for labeled cells. Which of
the following cell types will contain the label?
A. Astrocytes
B. Ependymal cells
C. Microglia
D. Oligodendroglia
E. Pseudounipolar cells

Answer
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Answers
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1The correct answer is B. The most specific clue in the description is the presence of erythematous patches with central clearing, known clinically as "target lesions," which are associated with erythema multiforme. Both erythema multiforme and its severe, life-threatening version, known as Stevens-Johnson syndrome, are produced by immune complex deposition in dermal blood vessels. In approximately 50% of patients, no specific precipitating cause is identified. In the remainder of patients, however, a variety of causes have been implicated, including certain infections (herpes simplex, enteroviruses, Mycoplasma pneumoniae, Chlamydia, histoplasmosis), drugs (penicillin, sulfonamides, phenytoin, aspirin, corticosteroids, cimetidine, allopurinol, oral contraceptives), neoplasia (leukemia, lymphoma, multiple myeloma, internal malignancy), sarcoidosis, and foods (notably emulsifiers in margarine).
Erythema migrans chronicum (choice A) also produces an annular erythematous rash with central clearing, but usually affects the thigh, groin, and axilla; it is associated with Lyme disease.
Kaposi's sarcoma (choice C) causes purple lesions with no target lesions.
Psoriasis (choice D) causes erythematous plaques with silvery scale but does not produce target lesions.
Urticaria (choice E) causes wheals that are intensely pruritic, but does not produce target lesions.
--------------------------------------------------------------------------------2The correct answer is C. Raloxifene is a selective estrogen receptor modulator that helps prevent osteoporosis by lessening bone resorption and reducing bone turnover. It lowers risk for vertebral fractures by 40% to 50%. It is a bone-preserving alternative for women who prefer to avoid estrogen. Raloxifene does not cause breast pain and may lessen the risk for breast cancer in menopausal women. There is also a favorable effect on LDL and cholesterol.
Calcitonin nasal spray (choice A) is an osteoclastic bone resorption inhibitor that modestly increases bone mineral density and reduces the incidence of vertebral fracture. Although it is an estrogen alternative for bone preservation, its impact on hip fracture is not known. It is also lacks the anti-breast cancer properties of raloxifene.
Oral conjugated estrogen (choice B) and transdermal estradiol (choice E) are not the best choices, as this patient wants to avoid estrogen because of a strong family history of breast cancer. The route of administration of estrogen has been shown to have similar effects on bone preservation, even though the transdermal dosage is generally half that of the oral dosage. Breast cancer risk, however, is slightly increased with the unopposed higher dosage oral estrogen replacement.
Tamoxifen (choice D), while indicated in the long-term care of breast cancer patients, is not alone useful for treatment or prevention of osteoporosis. Tamoxifen is an anti-estrogen agent that competes with estrogen for binding sites.
--------------------------------------------------------------------------------3The correct answer is B. The nerve is the axillary branch of the posterior cord (also called the axillary nerve), which can be damaged by either fracture or dislocations of the humeral neck. The muscle is the deltoid muscle, which is supplied by this nerve. The deltoid arises from the lateral portions of the clavicle and the acromion and inserts into the deltoid tuberosity of the humerus.
The deltoid arises from both the acromion (choice A) and the clavicle.
The deltoid does not arise from the coracoid process (choices C, D, and E).
--------------------------------------------------------------------------------4The correct answer is B. The patient has neurosyphilis, specifically general paresis, a term that means "general paralysis of the insane." In this late sequela of syphilitic infection which occurs 5 to 20 years after infection, patients develop mental deterioration, which precedes motor system deterioration, leading eventually to "general paralysis" with mutism and incontinence. The abnormalities may be conveniently recalled using paresis as a mnemonic for personality, affect, hyperactive reflexes, Argyll Robertson pupils in the eyes, defects in the sensorium, intellectual decline and deficient speech. Specific anti-treponemal tests such as FTA-ABS are usually positive on both serum and cerebrospinal fluid.
The cerebrospinal (CSF) glucose (choice A) in neurosyphilis is usually normal.
Gram's stain (choice C) of CSF will not demonstrate spirochetes in neurosyphilis.
The CSF lymphocyte count (choice D) is typically elevated in neurosyphilis, but this is a non-specific finding.
The CSF neutrophil count (choice E) is usually normal in neurosyphilis.
--------------------------------------------------------------------------------
5>The correct answer is A. The man described is probably suffering from avoidant personality disorder, characterized by feelings of inadequacy and extreme sensitivity to criticism, leading to social inhibition and withdrawal. These individuals often avoid interpersonal relationships entirely rather than subject themselves to the potential risk of criticism or rejection, although they may yearn for a more satisfying personal life.
Borderline personality disorder (choice B) is characterized by unstable interpersonal relationships, instability of affect, impulsivity, feelings of emptiness or anger and, in some cases, paranoid or dissociative symptoms.
Dependent personality disorder (choice C) is characterized by the need for constant support and reassurance, with unrealistic anxieties over being forced to fend for oneself.
Narcissistic personality disorder (choice D) is characterized by excessive grandiosity and an exaggerated sense of self-importance, accompanied by a feeling of entitlement and a need for attention or admiration.
Schizotypal personality disorder (choice E) is characterized by eccentricities of behavior, odd beliefs or magical thinking, and difficulties with social and interpersonal relationships.

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------6The correct answer is D. Respiratory syncytial virus is the most common cause of bronchiolitis and pneumonia in children younger than 1 year. Outbreaks occur seasonally in winter and early spring. Infection does not result in lasting immunity, and reinfection can occur.
Coronavirus (choice A) causes the common cold (nasal obstruction and discharge, sneezing, no fever or mild fever, occasional sore throat, and/or cough) and acute pharyngitis (sore throat, with or without cervical adenopathy, ulceration, and conjunctivitis).
Influenza type A (choice B) is the leading cause of influenza. Influenza is a systemic illness characterized by the sudden onset of fever, headache, myalgias, malaise, and prostration, followed by cough, nasal obstruction, and sore throat. The lower respiratory tract may also be involved.
Parainfluenza viruses (choice C) are the leading cause of croup, or acute laryngotracheobronchitis, in children. This infection involves both the upper and lower respiratory tracts. Inflammation in the subglottal area leads to hoarseness, dyspnea, a barking cough, and inspiratory stridor.
Rhinovirus (choice E) is the most common cause of the common cold.
--------------------------------------------------------------------------------7The correct answer is D. Maturation of germ cells (spermatogenesis) within the seminiferous tubules occurs in a concentric pattern with the less mature spermatogonia near the basal lamina and the mature forms near the tubule center. Spermatogonia are 2N cells and mature into larger primary spermatocytes (4N) (choice A). These mature into secondary spermatocytes (2N) (choice B), and finally into spermatids (1N) (choice C). Spermatids undergo spermiogenesis to become mature spermatozoa (choice E). Acrosomes form from the Golgi apparatus and a flagellum forms from microtubules. Unneeded organelles are shed. The seminiferous tubules of a reproductive-age male should exhibit all stages of maturation, with mature flagellated sperm in their centers.
--------------------------------------------------------------------------------
8The correct answer is C. The presentation described is classic for pulmonary hypertension, and, more specifically, the primary idiopathic form of pulmonary hypertension. This rare condition is suspected of being related to the collagen vascular diseases, since up to 50% of patients have antinuclear antibodies (despite the absence of frank presentation of other autoimmune disease). Also, a similar, known secondary form of pulmonary hypertension is sometimes seen in patients with a wide variety of collagen vascular diseases, including systemic lupus erythematosus, polymyositis, dermatomyositis, systemic sclerosis, and adult and juvenile forms of rheumatoid arthritis. A wide variety of other conditions have also been associated with secondary pulmonary hypertension, including shunts, left atrial hypertension, chronic hypoxia, pulmonary embolism, drug reaction, hepatic cirrhosis, and sickle cell disease. Both primary and secondary forms of pulmonary hypertension are associated with prominent changes in the pulmonary vasculature, which can include muscularization of smaller arterioles, concentric hypertrophy of the intima ("onion skinning"), and a distinctive plexiform lesion (plexogenic pulmonary vasculopathy) in which the smallest arterioles become markedly dilated with lumens partially occluded by endothelial (or possibly mesenchymal) cells and sometimes, thrombus. The prognosis of untreated pulmonary hypertension is poor. However, the use of the vasodilator hydralazine with anticoagulation can slow the course (fatal in about 3 years in untreated patients). If the pulmonary hypertension is secondary, therapy of the primary disease can be helpful.
Unlike cor pulmonale, atrial fibrillation with mural thrombus (choice A) formation is uncommon in primary pulmonary hypertension.
The absence of left ventricular findings on echocardiography tends to exclude myocardial infarction as the source of the patient's findings (choice B).
The presence of enlargement of the main pulmonary artery excludes pulmonary artery stenosis (choice D).
The clear lung fields exclude severe pulmonary fibrosis (choice E).
--------------------------------------------------------------------------------9The correct answer is B. The ureter leaves the renal pelvis and lies on the posterior abdominal wall as it descends to the pelvis. It crosses the pelvic brim at the level of the bifurcation of the common iliac artery. At this point it crosses anterior to the origin of the external iliac artery to enter the pelvis.
The origin of the common iliac artery (choice A) is at the bifurcation of the abdominal aorta, which occurs at the level of the fourth lumbar vertebra in the midline of the abdomen. Both ureters are lateral to the aortic bifurcation.
The origin of the internal iliac artery (choice C) is at the bifurcation of the common iliac artery, which occurs at about the level of the first sacral vertebra. The ureter and the internal iliac artery both enter the pelvis with the ureter on the lateral side of the artery.
The origin of the gonadal artery (choice D) (either the testicular artery or the ovarian artery) is from the abdominal aorta at a variable level, usually between the renal artery and the inferior mesenteric artery. The ureters are lateral to the origin of this artery.
The origin of the renal artery (choice E) is from the abdominal aorta at about the level of the second lumbar vertebra. The renal arteries pass laterally to enter the renal pelvis. At this site, the ureter is posterior to the artery.
--------------------------------------------------------------------------------10The correct answer is D. This is an example of relative polycythemia, in which there is an increased hematocrit or RBC count without a true increase in the total number of body RBCs. What usually happens in these cases is a significant reduction in plasma volume due to processes such as dehydration, vomiting, diarrhea, or diuresis.
Cyanotic heart disease (choice A), via appropriate erythropoietin secretion, can cause secondary absolute polycythemia.
Increased erythropoietin (choice B), whether appropriately or inappropriately secreted, can cause secondary absolute polycythemia.
Polycythemia vera (choice C) causes primary absolute polycythemia with usually low erythropoietin levels.
Renal cell carcinoma (choice E), via inappropriate erythropoietin secretion, can cause secondary absolute polycythemia.
--------------------------------------------------------------------------------11The correct answer is E. Hypospadias, which is congenital displacement of the urethral opening onto the ventral surface (underside) of the penis, is due to malformation of the urethral groove and canal. Hypospadias frequently accompanies other genitourinary anomalies, especially cryptorchidism. Isolated hypospadias is repaired because the abnormal opening is often constricted, leading to urinary retention and ascending urinary tract infections. Another important consequence of hypospadias is sterility, which occurs if the opening is too close to the base of the penis to permit normal ejaculation. Although hypospadias can occur in isolation, it is strongly associated with other urogenital anomalies.
Bladder exstrophy (choice A) is a completely unrelated congenital malformation in which the abdominal wall and anterior bladder wall form incompletely, and the bladder mucosa is exposed to the environment.
Hydrocele (choice B) is a serous accumulation in the tunica vaginalis, often producing a readily apparent scrotal mass. Hydrocele usually arises without any obvious cause.
Phimosis (choice C) is the condition in which the foreskin cannot be retracted over the head of the penis. It is usually either a congenital malformation or a consequence of scarring.
Urachal cysts (choice D) are produced by areas of persistent urachal epithelium, which may be present anywhere between the bladder and the umbilicus.
--------------------------------------------------------------------------------12The correct answer is E. Von Willebrand factor (vWF) is a self-polymerizing clotting protein present in the serum and the subendothelial basal lamina, which has binding sites for collagen, platelets, and fibrin. At a site of injury, vWF forms the bridge between the exposed collagen fibers and platelets in circulation, stimulating platelet degranulation and initiating the cellular component of the clotting cascade. An equally important role for vWF is binding platelets to the newly formed fibrin strands in a blood clot.
Factor VIII (choice A) and Factor IX (choice B) are clotting proteins of the intrinsic pathway. Factor VIII acts in concert with activated Factor IX (IXa) to cleave Factor X to Xa. Xa is the prothrombin activator central to both the intrinsic and extrinsic pathways.
Fibronectin (choice C) is a serum protein that acts as an opsonin for phagocytic cells in clots. Fibronectin binds non-specifically to bacteria and other materials in the newly forming clots, and draws the cell membrane of phagocytes into contact with these substances.
Tissue factor (choice D) is a protein released from injured tissues that works in concert with Factor VII to initiate the extrinsic pathway of coagulation. Like Factors VIII and IX, tissue factor and Factor VII cleave Factor X to Xa.
--------------------------------------------------------------------------------13The correct answer is D. The patient is most likely experiencing a potentiation of the effects of warfarin by norfloxacin, which decreases the metabolism of the warfarin. The increased warfarin effect produces an increase in the INR. (The target INR for patients with prosthetic heart valves is usually 1.5-4, depending on the type of valve.) Although norfloxacin is the most likely drug among the choices given to cause this effect in this patient, the antibiotics most commonly associated with this type of interaction are the macrolides, such as erythromycin, metronidazole, and the sulfonamide antibiotics.
Oral doses of penicillins, such as ampicillin (choice A), are generally not associated with a potentiation of warfarin's effect, although large IV doses of penicillin may be.
Cephalexin (choice B) is a first-generation cephalosporin that can be used in the treatment of acute cystitis. Although this agent is generally not associated with an increased hypoprothrombinemic effect when given with warfarin, the cephalosporins with a methyltetrazolethiol side chain, such as cefazolin, cefmetazole, and cefoperazone, are known to increase warfarin's therapeutic effect.
Nitrofurantoin (choice C) is a urinary anti-infective agent that does not interact with warfarin.
Phenazopyridine (choice E) is a urinary tract analgesic that does not interact with warfarin, although it commonly changes the color of urine to a bright orange/red color, which the patient may mistake as blood in the urine.
--------------------------------------------------------------------------------14The correct answer is D. Propylthiouracil works primarily by inhibiting the peripheral conversion of T4 to T3. The thyroid extracts iodide from the plasma and, in an oxidative process, iodinates tyrosine residues in thyroglobulin molecules. Monoiodotyrosines and diiodotyrosines are formed and then coupled to produce either thyroxine (tetraiodothyronine, T4) or triiodothyronine (T3). Proteolytic cleavage of thyroglobulin molecules leads to free T3 or T4, which is then released into the circulation; T3 is several times more potent than T4. Peripheral deiodination of T4 at the 5' position leads to T3 formation (mainly in the liver); this step is inhibited by propylthiouracil.
Decreasing the efficacy of TSH binding (choice A), decreasing the rate of thyroglobulin proteolysis (choice B), increasing the amount of rT3 formation (choice C), and inhibiting the uptake of iodide into the thyroid (choice E), would all tend to decrease the formation of thyroid hormones in the thyroid itself.
--------------------------------------------------------------------------------15The correct answer is A. Acetylcholine is the neurotransmitter of primary importance for the induction of REM sleep. Some of the other neurotransmitters do function in sleep, but REM sleep can occur in their absence.
Dopamine (choice B) is a neurotransmitter with a role in voluntary movement, mood, cognition, and regulation of prolactin release.
Epinephrine (choice C) is important in sympathetic nervous system responses. It is also a CNS neurotransmitter.
Norepinephrine (choice D) is important in sympathetic nervous system responses. It is also a CNS neurotransmitter involved in attention, arousal, and mood.
Serotonin (choice E) is a CNS neurotransmitter that plays an important role in mood and sensation. In the periphery, it is involved in vascular regulation and digestive function.
--------------------------------------------------------------------------------16The correct answer is E. This is a case of Neisseria gonorrhoeae arthritis. Patients are continuously susceptible to reinfection because of antigenic variation and phase variation of the pili.
N. gonorrhoeae is not an intracellular pathogen (choice A), although it may be found intracellularly in neutrophils after it has been phagocytized.
Ceftriaxone (choice B) is the drug of choice for N. gonorrhoeae.
Gonococci are especially susceptible to complement-mediated lysis, not resistant to it (choice C).
N. gonorrhoeae has an insignificant capsule that does not play a major role in the pathogenesis, but its capsule is immunogenic (compare with choice D). Streptococcus pyogenes is the best known example of a nonimmunogenic capsule, made of hyaluronic acid, but virtually all other capsules are immunogenic.
--------------------------------------------------------------------------------17The correct answer is E. Specificity is the proportion of persons without the disease who are correctly identified by the test as being disease-free. It is given by TN/(FP + TN), where TN stands for true negatives (people who do not have the disease and test negative on the test) and FP stands for false positives (people who do not have the disease but test positive on the test). In this case, 95/(5 + 95) = 95/100 = 0.95.
--------------------------------------------------------------------------------18The correct answer is B. 2,3-diphosphoglycerate (2,3-DPG) is produced in red cells by a variation on the glycolytic pathway, and levels diminish when glycolysis by the red cells slows. The depletion of 2,3-DPG in stored blood causes the hemoglobin dissociation curve to shift to the left, leading to an increase in oxygen affinity. This increase is helpful in the picking up of oxygen by hemoglobin in the lungs, but can be very problematic in the release of oxygen from the blood in tissues. This is not just a theoretical point: considerable effort has been expended in developing improved solutions for storing packed red cells and methods for "restoring" older stored cells so that the 2,3-DPG levels are adequate. In practice, in otherwise reasonably healthy patients, older transfused blood will quickly regenerate 2,3-DPG when placed in the glucose-containing environment of the serum, but even transiently decreased 2,3-DPG levels in a severely compromised patient can be dangerous.
--------------------------------------------------------------------------------19The correct answer is C. Entamoeba are relatively common enteric pathogens that can produce asymptomatic infection or more severe disease characterized by mucosal ulcerations and submucosal spread causing abdominal distress and liquid stools. Stools may show either trophozoite forms or the typical spherical cysts. Several species of Entamoeba are seen, including Entamoeba coli and E. hartmanni. E. histolytica cysts characteristically are spherical in shape, 10-20 mm in diameter, and have granular cytoplasm containing 1, 2, or 4 nuclei.
Cryptosporidium parvum (choice A) infections occur in the immunocompromised population and may cause severe diarrhea. The organism presents as minute (2-5 mm) intracellular spheres or arc-shaped merozoites under normal mucosa, and can be difficult to appreciate by light microscopy. Cysts in the stool are too small (4-5 mm) to be confused with Entamoeba.
Dientamoeba fragilis (choice B) is an intestinal amoeba that also may produce an infectious diarrhea. It does not have a cyst form, and only the trophozoite forms are seen in stools.
Giardia lamblia (choice D) is a flagellate protozoan that infects the stomach and small intestine when contaminated water is ingested. Diagnosis is usually made by examining duodenal contents; however, the stools may contain the oval or elliptical cysts, which are thick-walled and measure 8-14 mm in diameter. Spherical cysts are not seen in Giardia infection.
Isospora belli (choice E) produces self-limited intestinal infections mostly in the tropics, where fever and diarrhea may last weeks to months. The stool-borne cysts are much larger than Entamoeba (30 x 15 mm), are asymetrical, and are typically almond-shaped.
--------------------------------------------------------------------------------20The correct answer is A. The concrete operational stage (age 7-11 years) is defined by the child's awareness of the conservation of volume, which demonstrates that the child is able to reason in a logical way in terms of the physical world. Note that the child does not develop understanding of abstract concepts until he or she has reached the formal operational stage (choice B), at age 11 to adulthood.
The preoperational stage (choice C), ages 2 to 7 years, is associated with significant language development. However, the child has not yet developed the ability to take the perspective of others, and thus the child's thinking tends to remain egocentric.
The sensorimotor stage (choice D) corresponds to ages 0 to 2 years and is characterized by the infant developing increasingly sophisticated sensorimotor skills and behavior patterns.
--------------------------------------------------------------------------------21The correct answer is B. The reference intervals for serum alkaline phosphatase (ALP) and serum phosphate are higher in children than in adults. Growing bone in children requires alkaline phosphatase secreted by osteoblasts and an increase in serum phosphate to provide a proper solubility product ([calcium] x [phosphorus]) for mineralization of bone. However, the normal serum ALP in children is no greater than 5-times the upper limit of normal for adults, hence this patient's ALP is abnormally elevated. The most likely scenario is that the child is a victim of abuse and has suffered a femoral fracture that is healing. Bone repair further increases the serum ALP owing to the increase in osteoblastic activity.
Aseptic necrosis of bone in the leg (choice A) is more likely to occur in the femoral head (Legg-Calve-Perthes disease). This disease is more common in boys than girls and occurs in the 3- to 10-year-old age bracket. Although aseptic necrosis is associated with dense bone formation, it does not extend out into the soft tissue nor would it produce skin discoloration directly over the lesion (due to trauma in this case).
Since the elevation in serum ALP is increased for age and related to the bone lesion, choice C is incorrect.
Since the serum ALP is not normal for the age of this patient, choices D and E are incorrect. Furthermore, osteogenic sarcoma (choice D) does not normally occur in the first decade and favors the metaphysis of the distal femur or proximal tibia
--------------------------------------------------------------------------------22The correct answer is C. Norepinephrine (NE) is an agonist at alpha1-, alpha2- and beta1-receptors. NE exerts its vascular actions via alpha (predominantly alpha1) receptors and its cardiac actions via beta1-receptors. Labetalol is a nonselective antagonist at alpha- and beta-receptors, and therefore, could prevent all actions of NE.
Atenolol (choice A) is a selective beta1 antagonist, and therefore would block only norepinephrine's cardiac effects.
Esmolol (choice B) is a selective beta1 antagonist, and therefore would block only norepinephrine's cardiac effects. Metaproterenol (choice D) is a selective beta2 agonist and so would not block NE's effects.
Prazosin (choice E) is a selective alpha1 antagonist and would therefore block most of norepinephrine's actions in the vasculature, but would not antagonize other effects.
--------------------------------------------------------------------------------23The correct answer is C. The pudendal nerve is a branch of the sacral plexus that exits from the greater sciatic foramen and then enters the lesser sciatic foramen to lie in the pudendal canal on the lateral wall of the ischioanal fossa. The inferior rectal nerve is a branch of the pudendal nerve, which crosses the ischioanal fossa to reach the anal canal where it innervates the external anal sphincter and provides sensory innervation to the area.
The inferior gluteal nerve (choice A), a branch of the sacral plexus, exits through the greater sciatic foramen and innervates the gluteus maximus muscle.
The pelvic splanchnic nerves (choice B) are branches of the second, third, and fourth sacral nerves that carry preganglionic parasympathetic nerves to several pelvic organs.
The sciatic nerve (choice D) is a branch of the lumbosacral plexus that exits through the greater sciatic foramen, then enters the lower limb to innervate muscles of the posterior thigh, the leg, and the foot, and provides sensory innervation to the area as well.
The superior gluteal nerve (choice E) is a branch of the sacral plexus that exits through the greater sciatic foramen and innervates the gluteus medius, gluteus minimus, and tensor fascia latae muscles.
--------------------------------------------------------------------------------24The correct answer is A. The girl has Turner syndrome, which is specifically associated with coarctation of the aorta. Even when coarctation has not been diagnosed in early childhood and the patient appears to be doing well, surgical correction of any significant degree of coarctation is recommended. Uncorrected coarctation can cause death after about age 40 due to a variety of causes, including congestive heart failure, infective aortitis (analogous to infective endocarditis), and hypertension-induced intracranial hemorrhage or rupture of the damaged (pre-coarctation) aorta.
Associate dextrocardia (choice B) with Kartagener syndrome.
Associate ostium primum septal defect (choice C) with Down syndrome.
Pulmonary stenosis (choice D) and tetralogy of Fallot (choice E) are not specifically associated with Turner syndrome.
--------------------------------------------------------------------------------25The correct answer is A. The malignant tumor is a yolk sac tumor, also known as infantile embryonal carcinoma and endodermal sinus tumor. The biggest tip-off in the question stem is the presence of endodermal sinuses that resemble primitive glomeruli. The cytoplasmic globules described contain alpha-fetoprotein, indicating yolk cell differentiation, and alpha-1-antitrypsin. Alpha-fetoprotein can also be used as a serum marker for recurrent disease. Yolk sac tumors occur in pure form in infants and children and may be part of mixed tumors in adults.
Estrogen receptors (choice B) are important markers in breast cancer because they predict tumor response to hormonal manipulation.
Human chorionic gonadotropin (choice C) is found in the syncytial cells of embryonal carcinoma.
Human papilloma virus (choice D) can be found in condylomas, cervical cancer, penile cancer, laryngeal polyps, and warts.
Melanin (choice E) can be found in melanomas.
--------------------------------------------------------------------------------26The correct answer is D. The splenorenal ligament is the portion of the dorsal mesentery between the posterior abdominal wall and the spleen. This mesentery transmits the splenic artery and vein from their retroperitoneal position in the proximal portion of their course to the peritoneal spleen.
The gastrocolic ligament (choice A) is the portion of the greater omentum between the greater curvature of the stomach and the transverse colon. This portion of mesentery is not related to the spleen.
The gastrosplenic ligament (choice B) is the portion of the dorsal mesogastrium between the greater curvature of the stomach and the spleen. There are no splenic vessels in this mesentery.
The lesser omentum (choice C) is derived from the ventral mesentery. It is the mesentery between the lesser curvature of the stomach and the liver and between the first portion of the duodenum and the liver. It is not related to the spleen.
--------------------------------------------------------------------------------27The correct answer is D. This is one of those questions for which having a good idea of what you are looking for before exploring the answer choices will certainly save you valuable time. The answers all look alike and you could have been easily confused if you were not confident of the answer before approaching the choices.
This patient has long-standing hyperparathyroidism (elevated PTH), which predisposes to the development of osteitis fibrosa, her bone disease. PTH acts initially on osteocytes of bone tissue (osteocytic osteolysis) and subsequently on osteoclasts (osteoclastic resorption) to resorb calcium from bone matrix and make it available to the circulation. This increases plasma calcium levels. PTH also causes decreased phosphate reabsorption in the proximal renal tubule, yielding hypophosphatemia. Hypercalciuria is another sequela of excess PTH production, which predisposes the patient to the formation of calcium oxalate stones.
Choices A and E correspond to neither hyper- nor hypoparathyroid states.
Choice B is the profile of hypoparathyroidism. You should have quickly eliminated this choice since the PTH was decreased and you were looking for a profile consistent with HYPERparathyroidism.
Choice C is the profile of secondary hyperparathyroidism. This occurs when there is parathyroid overproduction due to a nonparathyroid cause. By far, the most common cause is chronic renal failure. In such cases, there is decreased calcium absorption since the kidneys are involved in the conversion of 25(OH)D3 to the active form 1,25(OH)D3. The decreased calcium ion level stimulates the parathyroid, leading to elevated PTH levels. Hyperphosphatemia results from diminished renal synthesis of 1,25 dihydroxyvitamin D3, creating further calcium-phosphate imbalance and enhanced PTH production.
--------------------------------------------------------------------------------28The correct answer is D. The processus vaginalis is an evagination of the parietal peritoneum of the abdomen that descends through the inguinal canal before the descent of the testis. Normally, the distal end of this evagination remains patent as the tunica vaginalis and the remainder of the processus vaginalis fuses and becomes fibrous. If a part of the processus vaginalis does not fuse (incomplete fusion), the resulting cystic structure is a hydrocele of the spermatic cord.
A communication between the epididymis and the tunica vaginalis (choice A) will result in the passage of sperm into the epididymis. This is a spermatocele.
Failure of the processus vaginalis to form (choice B) would result in an absence of the tunica vaginalis.
Total failure of the processus vaginalis to fuse (choice C) results in a persistent processus vaginalis. This results in congenital inguinal hernias.
Varicosities of the spermatic cord (choice E) or the pampiniform plexus is termed a varicocele.

Usmle-mcq's-8

2008-03-17T08:23:00.000-07:00

usmle-mcq's-7

2008-03-17T08:22:00.000-07:00

(42) <1>An 18-year-old college student presents to the student health
center complaining of a sore throat and fever. He describes feeling
tired for the past few days and reports a loss of appetite. On
examination, he has pharyngitis with cervical lymphadenopathy.
Blood tests reveal lymphocytosis and the presence of heterophil
antibodies. Which of the following best describes the virus
responsible for his illness?
A. Double-stranded, enveloped DNA virus
B. Double-stranded, nonenveloped DNA virus
C. Single-stranded, enveloped RNA virus
D. Single-stranded, nonenveloped DNA virus
E. Single-stranded, nonenveloped RNA virus

Answer
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<2>Which of the following organisms is a natural transformer?
A. Escherichia coli
B. Neisseria gonorrhoeae
C. Plasmodium vivax
D. Pseudomonas aeruginosa
E. Staphylococcus aureus
Answer
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<3>A child psychiatrist would like to evaluate the intellectual
ability of a 3-year-old patient. Which of the following is the
most appropriate test for him to use?
A. Denver Developmental Scale
B. Stanford-Binet Scale
C. WAIS-R
D. WISC III
E. WPPSI
Answer
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<4>A 57-year-old woman with a 30-year x 2 pack/day history of cigarette
smoking undergoes bronchoscopy. Biopsy of bronchial tissue show
s replacement of the normal pseudostratified ciliated columnar
epithelium with stratified squamous epithelium. This change
represents
A. dysplasia
B. hyperplasia
C. malignant transformation
D. metaplasia
E. necrosis and repair
Answer
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<5>A 25-year-old woman presents to her physician with complaints of
easy bruising and excessive bleeding. Physical examination demonstrates
hepatosplenomegaly. A blood smear reveals pancytopenia and a bone marrow
biopsy demonstrates markedly enlarged cells containing a fine fibrillar
material resembling tissue paper. Leukocyte enzymatic studies demonstrate
a deficiency of beta-D-glucosidase activity. Which of the following
substances is most likely to accumulate in the bone marrow cells?
A. Galactose
B. Glucosylceramide
C. Glycogen
D. Homocysteine
E. Mineralocorticoids
Answer
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<6>A 34-year-old HIV-positive man without previous opportunistic
infections presents complaining of dyspnea with daily activity. He
states that he has had a mild cough and fever but denies having had
chills, sputum production, or chest discomfort. Physical examination
is remarkable for oral thrush and a few small, nontender cervical
lymph nodes. A chest x-ray film reveals bilateral interstitial
infiltrates, and bronchoalveolar lavage reveals small silver-staining
cysts. In which other patient population in the U.S. is this organism
a frequent cause of a life-threatening pneumonia?
A. Bone marrow transplant patients
B. Hospitalized adults on antibiotic therapy
C. Late-term pregnant women
D. Normal adults in periods of stress
E. Premature infants
F. Preschool children
G. Sexually active adolescents
H. Third-trimester fetuses
Answer
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<7>A 28-year-old HIV-positive male complains of pain on swallowing.
Physical examination is remarkable for white plaque-like material
on his tongue and buccal mucosa, which is scraped and sent to the
laboratory. Based on these findings, and on the laboratory results
, the man is diagnosed with acquired immunodeficiency syndrome (AIDS).
With which of the following agents is the man most likely infected?
A. Candida albicans
B. Cytomegalovirus
C. Herpes simplex I
D. Human herpesvirus 8
E. Human papilloma virus
Answer
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<8>A superantigen is a bacterial product that
A. binds to B7 and CD28 costimulatory molecules
B. binds to the b chain of TCR and MHC class II molecules of APC stimulating T cell activation
C. binds to the CD4 + molecule causing T cell activation
D. is presented by macrophages to a larger-than-normal number of T helper CD4 + lymphocytes
E. stimulates massive amounts of IgG synthesis because of its large size
Answer
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<9>A young adult has progressive intellectual deterioration, weakness,
ataxia, and seizures. Reference laboratory tests demonstrate an
abnormality of an important mitochondrial enzyme. From which of
the following diseases is this person most likely suffering?
A. Adrenoleukodystrophy
B. Central pontine myelinolysis
C. Krabbe's disease
D. Leigh's disease
E. Metachromatic leukodystrophy
Answer
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<10>During a bitterly cold winter, an elderly couple is found dead in
their apartment. All of their windows are closed and their leaky old
furnace is on full. Which of the following is the primary mechanism
by which the toxin involved led to the death of this couple?
A. Decreasing intracellular calcium
B. Inhibition of cytochrome oxidase
C. Inhibition of Na+/K+ ATPase
D. Irreversibly binding to hemoglobin
E. Stimulation of cellular apoptosis
Answer
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<11>A child has a history of recurrent infections with organisms having
polysaccharide antigens (i.e., Streptococcus pneumoniae and Hemophilus
influenzae). This susceptibility can be explained by a deficiency of
A. C3 nephritic factor
B. C5
C. IgG subclass 2
D. myeloperoxidase in phagocytic cells
E. secretory IgA
Answer
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<12>A 32-year-old medical technician had a history of acute eczematous
dermatitis on her hands and wrist in the distribution of the latex gloves
she wore. The skin of her hands was dry, crusted, and thickened. The
eczematous reaction cleared after a 2-week vacation. After 72 hours
back on the job, the eczematous dermatitis returned and continued to
grow worse. Which of the following characterizes the technician's
reaction to the latex gloves?
A. Irritant dermatitis
B. Type I reaction
C. Type II reaction
D. Type III reaction
E. Type IV reaction
Answer
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<13>Cytotoxic T cells induced by infection with virus A will kill target
cells
A. from the same host infected with any virus
B. infected by virus A and identical at class I MHC loci to the cytotoxic T cells
C. infected by virus A and identical at class II MHC loci to the cytotoxic T cells
D. infected with any virus and identical at class I MHC loci to the cytotoxic cells
E. infected with any virus and identical at class II MHC loci to the cytotoxic cells
Answer
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14 .A 22-year-old female college student is brought into
the emergency room by the police, who found her walking back
and forth across a busy street, talking to herself. The young
woman appears to be oriented with respect to person, place,
and time. Her first hospital admission was two months ago
for a similar condition. During a psychiatric interview,
she has difficulty concentrating, and seems to hear voices.
A phone call to her sister provides the additional information
that the girl dropped out of school three months ago and has been
living on the street. Urine toxicology is negative. This patient
is most likely exhibiting the signs and symptoms of
A. schizoaffective disorder
B. schizoid personality disorder
C. schizophrenia
D. schizophreniform disorder
E. schizotypal personality disorder
Answer
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<15>A 4-month-old male presents with twitching of the facial muscles.
He has previously been seen for several severe episodes of Candida
infections. On examination, the child has low-set ears, hypertelorism,
and a shortened philtrum. What additional findings would be likely in
this individual?
A. Absent thymic shadow on chest x-ray
B. Decreased alpha-fetoprotein
C. Decreased IgA levels
D. Elevated IgM levels
E. Prominent telangiectasias around the eyes
Answer
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<16>A 16-year-old high school cheerleader presents with low grade fever,
pleuritic pain and a non-productive cough. Her serum agglutinates
Streptococcus salivarius strain MG. Therapy should include which of
the following?
A. Ampicillin
B. Erythromycin
C. Oxygen and external cooling
D. Penicillin G
E. Ribavirin
Answer
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<17>A 55-year-old male begins group therapy. After the first session, he
befriends one of the other clients, and begins telling her how
extraordinarily intelligent and talented the facilitator is. At
the next session, he and the facilitator disagree. After the
session, he tells his fellow group member that the facilitator
is utterly incompetent and that they should sue for malpractice.
This is an example of
A. displacement
B. fixation
C. reaction formation
D. regression
E. splitting
Answer
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<18>A 5-year-old girl is brought by her parents to the emergency room
because she is complaining of stomach pain. Physical examination reveals
multiple bruises on the child's body in different stages of healing.
X-ray examination of the chest demonstrates two cracked ribs, and the
child says, "Mommy hit me." The parents deny any abuse of their
children. The physician's most appropriate response would be:
A. "I am going to call the police right now."
B. "I must report this situation to Child Protective Services right now."
C. "I need to hospitalize this child for further studies."
D. "I will bind her ribs tonight and you must promise me that you will not strike this child again."
E. "I will bind her ribs tonight and you need to bring her to the outpatient clinic in the morning."
Answer
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<19>A 20-year-old woman sees her baby cousin for the first time. As she
attempts to play with the infant, he begins to cry incessantly. How old
is this baby likely to be?
A. 1-4 months
B. 5-8 months
C. 9-12 months
D. 13-16 months
E. 17-20 months
Answer
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<20>An IgG2 molecule is composed of which of the following?
A. One alpha, one gamma2, and two kappa chains
B. One gamma1 chain and two kappa chains
C. Two gamma1 chains and one kappa and one lambda chain
D. Two gamma1 chains and two kappa chains
E. Two gamma2 chains and two kappa chains
Answer
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<21>Which of the following is the most important costimulatory signal
provided to a T cell from an antigen-presenting cell?
A. B7 molecules interacting with CD 28
B. B7 molecules interacting with LFA- 1
C. ICAM-I interacting with LFA-1
D. LFA-3 interacting with CD 28
E. MHC class II interacting with T cell receptor
Answer
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<22>A febrile 12-year-old child presents with severe right lower quadrant
pain that is interpreted by the attending physician as acute appendicitis.
The patient has also been complaining of joint pain. At laparotomy, the
surgeon notes that the appendix is normal; however, the mesenteric lymph
nodes are markedly enlarged and contain focal areas of microabscess
formation on cut section. This patient is most likely
A. an asthmatic
B. deficient in C1 esterase inhibitor activity
C. HLA-B27 positive
D. leukopenic
E. serologically positive for toxoplasmosis
Answer
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<23>1. Degranulation of mast cells and basophils occurs when allergen binds
to two adjacent IgE antibodies on the membrane of the cell 2. Interleukin
4 released by CD4 helper T cells causes activated B cells to switch from
making IgM to IgE 3. Processed allergen is associated with a class II
molecule on an antigen presenting cell and recognized by CD4+ TH2 cells
4. Prostaglandins and leukotrienes are released 5. The allergen is
phagocytized and processed by a macrophage or a dendritic cell
Based on the numbered list above, which of the following is the
correct sequence of events in the Type I hypersensitivity reaction?
A. 1,2,3,5,4
B. 1,4,3,5,2
C. 1,5,2,3,4
D. 5,3,1,4,2
E. 5,3,2,1,4
Answer
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<24>An antibiotic, such as penicillin, which modifies cell wall synthesis,
tends to be most effective during which phase of bacterial growth in a
closed system?
A. Lag phase
B. Log phase
C. Phase of decline
D. Stationary phase
Answer
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<25>A 57-year-old woman with a history of hypertension and arthritis is
referred to a rheumatologist for evaluation. A complete blood count
(CBC) is normal, and a mini-chem panel shows no electrolyte abnormalities.
Her erythrocyte sedimentation rate (ESR) is elevated, and an antinuclear
antibody test (ANA) is positive. Further antibody studies are performed,
and the results are shown below.
Anti-histones high titer
Anti-double stranded DNA not detected
Anti-single stranded DNA not detected
Anti-SSA not detected
Anti-SSB not detected
Anti-SCI-70 not detected
Anti-Smith not detected
Anit-centromere not detected
Anti-RNP not detected
Which of the following diseases is suggested by these results?
A. CREST syndrome
B. Diffuse form of scleroderma
C. Drug-induced lupus
D. Sjِgren's syndrome
E. Systemic lupus erythematosus
Answer
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<26>A 65-year-old woman is evaluated for symmetrical swelling of the proximal phalangeal joints. Physical examination also reveals large subcutaneous nodules over the extensor surfaces of both arms. Autoantibodies directed against which of the following antigens would most likely be demonstrated by serum studies?
A. Acetylcholine receptor
B. Double stranded DNA
C. Histones
D. IgG
E. Ribonucleoprotein
Answer
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<27>A 6-year-old boy presents to the pediatric clinic with fever and earache. He has just finished an unsuccessful course of amoxicillin. On physical exam, his right tympanic membrane appears injected. Which of the following antimicrobials would be most appropriate to prescribe for this patient?
A. Amphotericin B
B. Bacitracin
C. Cefaclor
D. Erythromycin
E. Sulfamethoxazole
Answer
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<28>A 33-year-old woman is brought into the emergency room by ambulance.
She has been diagnosed as having schizophrenic disorder, disorganized
type, since the age of 17. She has been on antipsychotic medications
since that time, which have controlled her symptoms well. Physical
examination reveals a well-nourished female with a temperature of
103.2 degrees F, BP of 180/99, HR of 97, and copious perspiration.
She is mute, has muscular rigidity and appears to be obtunded.
Which of the following is the most likely diagnosis?
A. Acute dystonia
B. Akathisia
C. Neuroleptic malignant syndrome
D. Parkinsonism
E. Tardive dyskinesia

<29>In a closed system, spores are formed during which of the following
phases of bacterial growth?
A. Decline phase
B. Exponential phase
C. Lag phase
D. Log phase
E. Stationary phase
Answer
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<30>A 14-year-old boy is brought to the emergency department by his
parents because of high fever, headache, and stiff neck for the past
36 hours. He has become confused over the course of the morning. He
uses no medications, has no allergies, and is not sexually active.
On examination, he has a temperature of 38 C, moderate nuchal
rigidity, and marked photophobia. Lumbar puncture is performed,
and the cerebrospinal fluid shows: WBC 3500 with 95% PMNs, elevated
protein, decreased glucose, and gram-positive cocci in pairs and
short chains. By which of the following mechanisms does this
organism mediate its attachment to the respiratory mucosa?
A. Production of a C carbohydrate
B. Production of a hemolytic exotoxin
C. Production of a hyaluronic acid capsule
D. Production of an IgA protease
E. Production of an M protein
Answer
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<31>A 46-year-old woman presents with complaints of feeling as if she
has "sand in her eyes" and reports difficulty swallowing such foods
as crackers or toast. Which of the following pairs of tests would
likely yield positive results in this patient?
A. Anti-centromere antibody and rheumatoid factor
B. Anti-Scl-70 antibody and anti-Smith antibody
C. Anti-Smith antibody and anti-double stranded DNA antibody
D. Rheumatoid factor and anti-double stranded DNA
E. Rheumatoid factor and anti-SS-A antibody
Answer
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<32>A viral organism was isolated from a painful blister on the lip of
a teenage girl. The agent was found to double-stranded, linear DNA and
was enveloped. The patient had a similar sore approximately 2 months
ago. Which of the following is the most likely causative organism?
A. Adenovirus
B. Coxsackie virus
C. Herpes simplex type 1 virus
D. Herpes zoster virus
E. Papilloma virus
Answer
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<33>A British dairy farmer develops fever with chills, myalgias, headache,
skin rash, and vomiting. He is quite ill and is hospitalized. Blood
cultures demonstrate tightly coiled, thin, flexible spirochetes shaped
like a Shepherd's crook. The spirochetes are easily cultured in
serum-enriched nutrient agar. Which of the following organisms
should be suspected?
A. Brucella abortus
B. Brucella melitensis
C. Leptospira interrogans
D. Pseudomonas mallei
E. Pseudomonas pseudomallei

<34>A hospitalized patient develops dysuria and suprapubic pain and is
treated with ciprofloxacin. What is the mechanism of action of this
antibiotic?
A. It inhibits dihydrofolate reductase
B. It inhibits DNA-dependent RNA polymerase
C. It inhibits protein synthesis by binding to the 30s ribosomal subunit
D. It inhibits protein synthesis by binding to the 50s ribosomal subunit
E. It inhibits topoisomerase II (DNA gyrase)
Answer
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<35>A 58-year-old alcoholic man with multiple dental caries develops a
pulmonary abscess and is treated with antibiotics. Several days later,
he develops nausea, vomiting, abdominal pain, and voluminous green
diarrhea. Which of the following antibiotics is most likely responsible
for this patient's symptoms?
A. Chloramphenicol
B. Clindamycin
C. Gentamicin
D. Metronidazole
E. Vancomycin
Answer
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<36>A 36-year-old farmer has been exposed to poison ivy on several
different occasions and usually develops very severe skin lesions.
He enrolls in an immunological study at an urban medical center. A
flow cytometric measurement of T cells reveals values within the
normal range. An increased serum concentration of which of the following
cytokines would decrease the likelihood of a delayed-type hypersensitivity
reaction in this individual?
A. Gamma interferon
B. IL-2
C. IL-4
D. IL-8
E. IL-10
Answer
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<37>A 22-year-old male is evaluated for mitral regurgitation due to mitral
valve prolapse. Examination reveals a tall, slender young man with long
extremities and long tapering fingers. Pupillary dilation followed by
slit-lamp examination reveals bilateral dislocation of the lenses of
the eyes. This patient is potentially at increased risk for development
of
A. aortic dissection
B. Lisch nodules
C. noncaseating granulomata
D. progressive dementia
E. rapidly progressive renal failure
Answer
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<38>A 57-year-old man is seen in clinic for a chronic cough. Chest x-ray
demonstrates a lung mass; bronchoscopy with bronchial lavage and biopsy
reveals a tumor composed of small neoplastic cells with prominent crush
artifact that do not stain with immunohistochemical stains for lymphocyte
common antigen (LCA). Which of the following oncogenes has been
associated with this tumor?
A. bcl-2
B. erb-2
C. L-myc
D. N-myc
E. ret
Answer
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<39>Which of the following features characterizes apoptosis but not
necrosis?
A. Disaggregation of polyribosomes
B. Eosinophilia
C. Inflammation
D. Karyolysis
E. Peripheral aggregation of chromatin
Answer
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<40>A woman who is heterozygous for glucose-6-phosphate dehydrogenase
(G6PD), a polymorphic enzyme transcribed from the X chromosome, develops
chronic myeloid leukemia. Restriction fragment length polymorphism (RFLP)
studies on the tumor cells for G6PD reveal that only a single form of the
enzyme is transcribed. This finding supports which of the following
features of neoplasia?
A. Genetic mutation
B. Monoclonality
C. Mosaicism
D. Oncogene activation
E. Point mutation
Answer
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<41>What is the role of the macrophage during antibody formation?
A. Activation of cytotoxic CD8 T cells
B. Delayed hypersensitivity reaction
C. Lysis of virus-infected cells
D. Processing antigen and presenting it to T helper CD4 cells
E. Synthesis of immunoglobulin
Answer
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<42> The patient shown in the pedigree above did poorly in school,
then became increasingly forgetful and irrational. Over a period of
years, he developed ataxia and began posturing. Eventually, he was
demented and unable to care for himself. At autopsy, extensive cortical
demyelination is observed. Microscopic examination of the areas of
demyelination reveals numerous macrophages containing crystals that
stain a light brown color with toluidine blue. This presentation is
probably due to a deficiency of
A. arylsulfatase A
B. galactocerebroside b-galactosidase
C. glucocerebrosidase
D. hexosaminidase A
E. sphingomyelinase
Answer
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<43>A 46-year-old female with rheumatoid arthritis develops progressively
worsening renal failure. She undergoes diagnostic renal biopsy, revealing
thickening of the mesangial matrix and widened capillary basement
membranes due to deposition of an amorphous, eosinophilic material
that stains with Congo red. The material is shown to be composed of
AA (amyloid-associated) protein fibrils. In which of the following
locations is this protein synthesized?
A. Bone marrow
B. Brain
C. Liver
D. Synovium
E. Thyroid
Answer
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<44>A 38-year-old woman complains of cold, painful fingertips, as well
as difficulty swallowing and indigestion. Physical examination is
remarkable for a thickened, shiny epidermis over the entire body,
with restriction of movement of the extremities, particularly the
fingers, which appear claw-like. Which of the following autoantibodies
is likely to be found in this patient's serum?
A. Anti-DNA topoisomerase I (anti-Scl-70)
B. Anti-double-stranded DNA (ds DNA)
C. Anti-IgG
D. Anti-Sm
E. Anti-SS-A
Answer
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<45>A 67-year-old male smoker presents to his physician for a routine
physical examination. Chest x-ray demonstrates a 2-cm density on the
left side. Laboratory studies are remarkable for a serum sodium of
134 mEq/L. The findings may be attributable to tumor cell secretion
of
A. adrenocorticotrophic hormone (ACTH)
B. antidiuretic hormone (ADH)
C. melanocyte-stimulating hormone (MSH)
D. parathyroid hormone (PTH)
E. vasoactive intestinal polypeptide (VIP)
Answer
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<46>A 28-year-old mother gives birth to her first child. The father
is homozygous Rh D positive and the mother is homozygous Rh D negative.
The baby is born without any complications, but the mother is not given
RhoGAM (anti-Rh IgG) following the delivery. Eighteen months later she
delivers another child, who is anemic, slightly jaundiced, and has an
enlarged spleen and liver. Which type of hypersensitivity best
describes this condition?
A. Atopic disease
B. Cytotoxic disease
C. Delayed hypersensitivity
D. Immediate hypersensitivity
E. Immune complex disease
Answer
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<47>A 24-year-old female has fever, malaise, and a dry, nonproductive
cough. She also complains of headache, muscle aches, and leg pain. Lab
values are significant for elevated cold agglutinins. Which of the
following microorganisms is responsible for her symptoms?
A. Haemophilus influenzae
B. Klebsiella pneumoniae
C. Legionella pneumophila
D. Mycoplasma pneumoniae
E. Streptococcus pneumoniae
Answer
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<48>A 29-year-old news correspondent returns from covering an earthquake
and its aftermath in a third world country. The man feels tired and has
sore muscles, so he consults a physician, who examines him, but decides
not to admit him to the hospital. The man subsequently develops a
disabling illness complicated by severe anemia, pulmonary edema,
renal failure, and shock. Which of the following organisms is the
most likely pathogen?
A. Babesia microti
B. Plasmodium falciparum
C. Plasmodium malariae
D. Plasmodium ovale
E. Plasmodium vivax
Answer
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<49>A 12-year-old boy has a productive cough characterized by large
volumes of foul-smelling sputum. Three years ago, the patient was
diagnosed with pancreatic insufficiency, as evidenced by repetitive
gastrointestinal symptoms of steatorrhea. After culture of the sputum,
colorless, oxidase-positive colonies with a fruity aroma develop on the
agar. The function of which of the following proteins is most likely
inhibited by the bacteria responsible for this boy's infection?
A. A CFTR protein lacking a phenylalanine in exon 10 at position 508
B. A GTP-binding protein involved in the elongation step of protein synthesis
C. A GTP-binding protein similar to the one coupled with a2-adrenergic receptors
D. A GTP-binding protein similar to the one coupled with b-adrenergic receptors
E. A phosphorylation-regulated chloride channel in the apical membrane of epithelial cells
Answer
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<50>Which of the following genes involved in the synthesis of
immunoglobulins are linked on a single chromosome?
A. C gene for gamma chain and C gene for alpha chain
B. C gene for gamma chain and C gene for kappa chain
C. V gene for kappa chain and C gene for the epsilon chain
D. V gene for lambda chain and C gene for kappa chain
E. V gene for lambda chain and V gene for heavy chain

Answer
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Answers
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1>The correct answer is A. This is one of those USMLE-style items where figuring out the diagnosis is the easy part and remembering the basic science details is much tougher. In this case, the patient has all the hallmarks of mononucleosis (the heterophil antibodies should have confirmed your suspicion from the history and physical). Mononucleosis is caused by the Epstein-Barr virus, which, in turn, belongs to the herpesvirus family. The herpesviruses are enveloped viruses with double-stranded DNA. Remember that in addition to Epstein-Barr virus, the herpesvirus family also includes herpes simplex (1 and 2), varicella-zoster (chickenpox, shingles), and cytomegalovirus (infection in immunocompromised). Cytomegalovirus also causes infectious mononucleosis, but in these patients the heterophil test is negative.
There are two families of viruses that are nonenveloped with double-stranded DNA (choice B): papovaviruses and adenoviruses.
There are many families of viruses that are enveloped with single-stranded RNA (choice C): arenaviruses, bunyaviruses, coronaviruses, filoviruses, flaviviruses, paramyxoviruses, orthomyxoviruses, retroviruses, rhabdoviruses, and togaviruses.
Parvoviruses are the only family of DNA virus with single-stranded DNA. They do not have an envelope (choice D).
There are two families of RNA virus that are single-stranded without an envelope (choice E): caliciviruses and picornaviruses.

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2>The correct answer is B. Transformation is the uptake and integration of naked DNA by a bacteria from the environment. Transformation can be induced in the laboratory (a technique used to introduce gene-carrying plasmids into bacteria) or, relatively uncommonly, occurs naturally. Only a few medically important species undergo natural transformation: Haemophilus species, Streptococcus species, Neisseria gonorrhoeae, and Helicobacter pylori.
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3>The correct answer is B. The Stanford-Binet scale is best for younger children (2-4 years old), since it does not rely exclusively on language.
The Denver Developmental Scale (choice A) is used to assess the attainment of developmental milestones in children under 2.
The WAIS-R (Wechsler Adult Intelligence Scale; choice C) is used for individuals aged 17 and over. (Just think, the WAIS-R is rated "R").
The WISC III (Wechsler Intelligence Scale for Children; choice D) is useful for evaluating children aged 6-16.
The WPPSI (Wechsler Preschool and Primary Scale of Intelligence; choice E) is used for children aged 4-6.

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4>The correct answer is D. Squamous metaplasia is a frequent airway response to chronic irritation from cigarette smoking. It represents the replacement of one differentiated tissue with another mature, differentiated tissue. It is believed that the squamous epithelium is more resistant to injurious agents, and so represents an adaptive response.
Dysplasia (choice A) is characterized by pleomorphism (the individual cells may vary widely in appearance) and by loss of normal tissue architecture, rather than by replacement with another mature epithelium (squamous).
Hyperplasia (choice B) refers to growth of a tissue or organ by cellular proliferation.
Malignant transformation (choice C) is the multistep process by which normal cells progress to the "cancer" phenotype. Metaplasia is not malignant transformation, although the stimuli producing metaplasia may also be associated with the development of malignancy.
Necrosis and repair (choice E) typically result in re-epithelialization and/or fibrosis, not metaplasia.
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5>The correct answer is B. The disease is Gaucher disease, which is a glycolipid storage disease in which glucosylceramide accumulates in spleen, liver, and bone marrow. The defective enzyme, a lysosomal hydrolase known as acid beta-D-glucosidase, can be assayed in leukocytes separated from the blood by centrifugation. Interestingly, the defective enzyme can now be supplied intravenously, and strategies for transplantation of the cloned replacement gene are now being developed.
Galactose (choice A) is a sugar. Deficiency of beta-D-glucosidase would not lead to accumulation of galactose.
Glycogen (choice C) is a storage polymer of glucose. It accumulates in various glycogen storage diseases, but has a different appearance than the glycolipid in Gaucher disease.
Homocysteine (choice D) is an amino acid. It does not accumulate in Gaucher disease.
Mineralocorticoids (choice E) are lipids, but do not accumulate in bone marrow.

6>The correct answer is E. This patient has Pneumocystis carinii pneumonia, the most common atypical pneumonia in AIDS patients. The next most common pool of at-risk individuals consists of premature infants.
Bone marrow transplant patients (choice A) would be immunologically compromised, and might be a second at-risk group (behind premature infants), but would not be the first choice on this list.
Hospitalized adults on antibiotic therapy (choice B) might be slightly immunologically compromised or stressed, but are not the major patient pool at risk for this infection in the U.S.
Late-term pregnant women (choice C) are not immunologically compromised and would not be at risk.
Normal adults in periods of stress (choice D) are not particularly susceptible to opportunistic pathogens.
Preschool children (choice F) have normal rates of exposure to P. carinii, as would any adult, but are not susceptible to serious pneumonia with this agent unless they are immunologically suppressed.
Sexually active adolescents (choice G) would have the same infection rates as normal infants and adults, but again would not be susceptible to life-threatening pneumonia. P. carinii is transmitted via aerosols, not sexual activity.
Third-trimester fetuses (choice H) are not susceptible to infection with this fungus, although they may become infected in utero with HIV.
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7>The correct answer is A. Candida albicans produces oral thrush, an AIDS-defining lesion, which is common in acute HIV disease, and becomes increasing common as the CD4 + cell count falls. The lesions are usually painless. Diagnosis is by demonstration of pseudohyphae using a wet smear with confirmation by culture.
Although cytomegalovirus (choice B) is associated with numerous clinical scenarios in the AIDS population, including odynophagia (painful swallowing), it would not produce white plaques on the oral mucosa.
Herpes Simplex I (choice C) produces vesicular lesions occurring in clusters in the oral cavity. There is an increased risk of herpes infections in the AIDS group, but the lesions do not resemble those described in the question.
Human herpesvirus 8 (choice D) is the causative agent of Kaposi's sarcoma, a malignancy arising from endothelial cells that appears as hemorrhagic nodules in different organ systems. It is the most common cancer in the HIV infected population.
Human papilloma virus (choice E) is associated with a variety of lesions, including warts and intraepithelial neoplasias of the vulva and cervix. It is associated with anal condyloma, which can occur in the AIDS population.
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8>The correct answer is B. A superantigen, such as TSST- 1 or staphylococcal enterotoxin, cross-links the variable domain of the TCR b chain to the MHC class II molecule and specifically induces massive T cell activation.
The superantigen does not bind the B7 and CD28 costimulatory molecules (choice A). Instead, the costimulatory molecules bind to each other to stimulate the reaction between the antigen-presenting cell and T cell.
The superantigen does not bind the CD 4 molecules (choice C) but instead binds on the other side of the TCR receptor complex.
The term superantigen has nothing to do with the antigen being presented by macrophages to T cells (choice D).
The term superantigen has nothing to do with its size or its ability to stimulate antibody production (choice E). The term superantigen is used because of its unusual ability to create massive T cell activation by the unique type of binding.

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9>The correct answer is D. Leigh's disease, also known as subacute necrotizing encephalomyelopathy, is a very rare disease that most physicians will never encounter in real life. However, it may show up on the USMLE because it is one of the few examples of diseases involving defects in the mitochondrial DNA rather than the chromosomal DNA. The specific defective enzyme, in at least some cases, is cytochrome oxidase, one of the components of the electron transport system. Muscle and brain are particularly affected. Patients have the presentation described in the question and typically die within several years.
Adrenoleukodystrophy (choice A) is an X-linked disease with abnormal lipid metabolism leading to demyelination in the CNS.
Central pontine myelinolysis (choice B) is characterized by demyelination of the pons (especially the basis pontis) seen after overlying rapid correction of hyponatremia.
Krabbe's disease (choice C) is an autosomal recessive accumulation of cerebrosides in histiocytes in the CNS.
Metachromatic leukodystrophy (choice E) is an autosomal recessive accumulation of sphingolipids in the CNS and elsewhere.
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10>The correct answer is D. This couple died of carbon monoxide poisoning. Carbon monoxide has approximately 240 times the affinity for hemoglobin than does oxygen. In a sense, the hemoglobin-CO dissociation curve is shifted very far to the left compared to the hemoglobin-O2 dissociation curve. This means that the binding of hemoglobin to carbon monoxide is virtually irreversible. (The carbon monoxide that cigarette smokers inhale is cleared only when senescent red cells are phagocytized in the spleen and the hemoglobin is degraded.) In addition, the carbon monoxide shifts the hemoglobin-O2 dissociation curve to the left, making the unloading of O2 to the tissues very difficult. When too much hemoglobin is tied up with carbon monoxide, the person dies. The carbon monoxide-hemoglobin complex has a bright red color; a distinctive feature of carbon monoxide poisoning that can be helpful either at autopsy or in living patients is that this color makes the skin and organs also appear bright cherry red.
Generally, intracellular calcium levels increase, rather than decrease (choice A), with cellular injury or death.
Cytochrome oxidase is inhibited by cyanide (choice B).
Ouabain is an example of a poison that inhibits Na+/K+ ATPase (choice C).
Apoptosis (programmed cell death) is stimulated (choice E) by certain genes (e.g., p53, ced 3,4), glucocorticoids, and aging.
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11>The correct answer is C. IgG is the predominant antibody in the secondary immune response. IgG subclass 2 is directed against polysaccharide antigens and is involved in the host defense against encapsulated bacteria.
C3 nephritic factor (choice A) is an IgG autoantibody that binds to C3 convertase, making it resistant to inactivation. This leads to persistently low serum complement levels and is associated with Type II membranoproliferative glomerulonephritis.
C5 (choice B) is a component of the complement system. C5a is an anaphylatoxin that effects vasodilatation in acute inflammation. It is also chemotactic for neutrophils and monocytes and increases the expression of adhesion molecules. A deficiency of C5a would affect the acute inflammatory response against any microorganism or foreign substance.
Myeloperoxidase in phagocytic cells (choice D) is an element of the oxygen-dependent pathway present in phagocytic cells that effectively kills bacterial cells. The hydrogen peroxide-halide complex is considered the most efficient bactericidal system in neutrophils. Chronic granulomatous disease is associated with a deficiency of NADPH oxidase, which converts molecular oxygen to superoxide (the first step in the myeloperoxidase system). Patients are susceptible to granulomatous infections and staphylococcal infections.
Secretory IgA (choice E) is the immunoglobulin associated with mucous membranes. Selective IgA deficiency is the most common hereditary immunodeficiency. In this disorder, there is failure of the B cell to switch the heavy chain class from IgM to IgA. Patients have an increased incidence of sinopulmonary infections, diarrhea, allergies, and autoimmune diseases.

12>The correct answer is E. Sensitization to latex has become a major healthcare problem. Local skin irritations are common but more severe allergic reactions occur, up to and including rare anaphylactic reactions that are occasionally fatal. The immune responses to latex are immediate-type hypersensitivity (type I) reactions, expressing themselves in minutes, and/or delayed-type hypersensitivity (type IV) reactions, which will express themselves in 48-72 hours. The type I reactions are due to the IgE-mediated sensitivity to latex proteins while the type IV reactions are due to a cell-mediated response to the chemicals that are added in the processing of latex. The type IV response in this circumstance would be referred to as contact dermatitis.
Irritant dermatitis (choice A) can be observed in the early stages of sensitization and can be due to sweating, rubbing, and residual soap. The timing of the reaction after 72 hours points to the type IV reaction rather than an irritant dermatitis.
A type I reaction (choice B) would have been apparent in minutes with characteristic rhinitis, conjunctivitis, urticaria, asthma, angioedema, or anaphylaxis after she put on her latex gloves.
A type II reaction (choice C) is a cytolytic response mediated by an antibody. The type II reaction is observed in the context of hemolytic anemias, thrombocytopenia, neutropenia, etc.
A type III reaction (choice D) is an immune-complex response that sets into motion an inflammatory response.
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13>The correct answer is B. The CD8+ cytotoxic T cells have antigen specific T-cell receptors (TCR) on their membranes that will recognize and bind to self class I antigens. Since the viral peptides are presented as a complex with the self class I antigens, the CD8+ cells can now recognize and react to the virus A peptides. Remember that class I antigens are expressed on all nucleated cells and platelets.
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14>A
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15>The correct answer is A. The clinical findings describe DiGeorge syndrome. Patients clinically present with tetany (usually first noted in the facial muscles) due to hypocalcemia secondary to hypoparathyroidism. The thymus is absent, as are the parathyroid glands, due to failure of development of the 3rd and 4th pharyngeal pouches. Recurrent infections due to defective cellular immunity and abnormal facies are additional features.
Decreased alpha-fetoprotein (choice B) is an amniotic fluid marker for Down's syndrome. Down's syndrome patients have abnormal immune responses that predispose them to serious infections (particularly of the lungs) and to thyroid autoimmune disease. However, there is no defect of the parathyroid glands.
Decreased IgA levels (choice C) describes selective IgA deficiency, which is the most common hereditary immunodeficiency. The syndrome is due to a failure of heavy-chain gene switching in B cells.
Elevated IgM (choice D) is seen in hyper-IgM syndrome. Patients have a high concentration of IgM and normal numbers of T and B cells, but low levels of IgG, IgA, and IgE. Helper T cells have a defect in the surface protein CD40 ligand that interacts with CD40 on the B-cell surface. This results in an inability of the B cell to switch from the production of IgM to other classes of antibodies.
Prominent telangiectasias around the eyes (choice E) are seen as part of the ataxia-telangiectasia syndrome. This is an autosomal recessive disorder, and is also referred to as a chromosomal breakage syndrome. Ataxia-telangiectasia is associated with increased numbers of translocations, especially involving the T-cell receptor loci; the gene for this disorder has been mapped to chromosome 11. Patients have an increased incidence of malignancy.
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16>The correct answer is B. The patient has primary atypical pneumonia caused by Mycoplasma pneumoniae. These organisms are fastidious and difficult to culture in the laboratory, however serodiagnosis can be most helpful. Patients produce one or two heterophile antibodies during the course of the infection: one agglutinates human O+ RBCs in the cold (the cold hemagglutinins) while the other causes the agglutination of a strain of Streptococcus salivarius termed strain MG (the Strep MG agglutinins). Mycoplasma are susceptible to the macrolide family of antibiotics (erythromycin, clarithromycin, etc.). These organisms lack a cell wall, hence they are indifferent to antibiotics that interfere with peptidoglycan synthesis, such as penicillin (choice D) and ampicillin (choice A).
Oxygen and external cooling (choice C) are therapeutic measures that are used in the treatment of severe respiratory diseases such as pneumococcal pneumonia.
Ribavirin (choice E) is used in the treatment of respiratory syncytial virus infection in infants. This is the most common cause of hospitalization for respiratory disease in the very young, probably because aerosol administration of the antiviral compound is best accomplished in a hospital setting.
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17>The correct answer is E. Splitting is a primitive defense mechanism in which objects or people are thought of as either "all bad" or "all good." This defense mechanism is normal in young children, but also occurs in adults with borderline personality disorder (the man in group therapy) or psychosis.
Displacement (choice A) is an unconscious defense mechanism in which one's feelings or desires are unconsciously transferred from their original object to a more acceptable substitute.
Fixation (choice B) refers to an arrest of development at a particular developmental stage. It is generally a partial or incomplete arrest of development, but can contribute to the development of emotional problems if protracted.
Reaction formation (choice C) refers to an unconscious defense mechanism in which the person takes on an attitude or belief that is the opposite of his or her true beliefs and desires.
Regression (choice D) is a return to an earlier (often infantile) stage of development that occurs in many mental illnesses and in normal individuals experiencing tragic or extremely stressful events.
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18>The correct answer is B. All signs, including the child's report, suggest child abuse; however, there can be mitigating circumstances that are present. All states have laws requiring everyone to protect children by reporting the suspicion of child abuse to Child Protective Services. It is the responsibility of this agency to prove or disprove the suspicion, and to establish supervision of the child if abuse is verified.
"I am going to call the police right now" (choice A), is only appropriate if the Child Protective Services is not available immediately.
Choices C, D, and E do nothing to address the issue of the mandatory report of the suspicion of child abuse to the appropriate authorities.
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19>The correct answer is B. The baby is exhibiting stranger anxiety, which normally occurs between the ages of 5 and 9 months.
Let's review some other social milestones that are good to be aware of during clinical work in pediatrics:
Spontaneous smiling begins within several days after birth and disappears by 3 months. Smiling at any face occurs by 2 months, followed quickly by smiling only at familiar faces and when pleased. By 3 months, infants can imitate facial expressions. They laugh at 4 months.
Crying occurs from birth. It peaks at 6 weeks and is most frequent from 4-6 p.m. Colic is defined as crying more than 3 hours a day for more than 3 days a week. It often spontaneously resolves by 4 months. Treatment includes holding, avoiding overstimulation, and antispasmodics.
Separation anxiety occurs between the ages of 10 and 18 months, when the infant is separated from the mother.
Between the ages of 2 months and 2 years, children might show preference for a comforting "transitional object" (e.g., teddy bear), which is usually discarded by age 4, when the transition from dependence on the mother to independence is more complete.
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20>The correct answer is E. IgG molecules contain two gamma heavy chains of a given subtype and two light chains (either kappa or lambda). The 2 in IgG2 indicates the subclass to which the molecule belongs. IgG2 contains two gamma2 chains (since a given B cell can only form one type of heavy chain). The IgG molecule will contain either two kappa chains or two lambda chains, but never one of each (choice C).
A given cell produces immunoglobulin molecules with a single type of heavy chain (compare with choice A).
IgG molecules with gamma1 chains (choices B, C, and D) would be of the IgG1 subclass.
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21>The correct answer is A. The B7 molecule on the cell surface of the antigen-presenting cell reacts with the CD 28 molecule on the T cell surface for maximal costimulatory signals.
The B7 molecule on the surface of the antigen presenting cell reacts only with CD 28 and does not react with LFA-1 (choice B) adhesion molecule.
The ICAM- I on the surface of an antigen presenting cell reacts with the LFA- I (choice C) on the surface of a T cell for the purpose of cell-to-cell adhesion and does not function for costimulation.
The LFA-3 (CD58) is an adhesion molecule on the surface of an antigen presenting cell. It does not react with a CD28 (choice D) costimulatory molecule on the T cell surface.
The MHC class II molecule with its epitope does interact with a specific T cell receptor (TCR) (choice E), but this is not termed costimulatory. However, the interaction does stimulate the T cell to produce interleukins for further cell division
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22>The correct answer is C. Yersinia enterocolitica is the pathogen producing this clinical syndrome. Yersinia is transmitted to patients via the oral route, via contaminated blood products, or by cutaneous inoculation. Patients developing iron overload because of multiple transfusions (i.e., thalassemia patients) are at increased risk of Yersinia infections because some strains are unable to synthesize bacterial iron chelators called siderophores. They can, however, use host-chelated iron stores or the drug deferoxamine (a siderophore produced by Streptomyces pilosus). Yersinia is associated with reactive arthritis following an infection by an enteropathogenic organism. Most patients who develop arthritis express HLA-B27.
A history of asthma (choice A) is not associated with Yersinia infections.
Deficiency in C1 esterase inhibitor activity (choice B) produces the syndrome of angioedema. This is an autosomal dominant trait associated with a deficiency of the serum inhibitor of the activated first complement component. The patients have multiple episodes of edema, affecting skin and mucosal surfaces such as the larynx and the GI tract.
Leukopenia (choice D) is not associated with the clinical scenario in the question. Normal-to-elevated leukocyte counts are the rule in Yersinia infection.
Serological positivity for toxoplasmosis (choice E) is not suggested because toxoplasmosis produces a different clinical picture. Toxoplasmosis can be acquired transplacentally with infected infants exhibiting a wide array of symptoms depending on when the mother was infected during gestation. Toxoplasmosis is also seen in immunocompromised patients such as those with AIDS. In this group of patients, the main organ system involved is the central nervous system.
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23>The correct answer is E. This question illustrates an important point. An allergen or antigen must first be processed by an antigen-presenting cell in an unsensitized host before the CD 4+ T helper cells can react to it. These cells of the TH2 subclass then produce a variety of cytokines including interleukin 4. Interleukin 4 causes the heavy chain switching in the B cells from IgM to IgE. The IgE binds to the surface of mast cells or basophils by the Fc fragment. When the patient is re-exposed to the sensitizing allergen, the IgE binds to the allergen and causes degranulation of the mast cell or basophil.

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24>The correct answer is B. Bacterial growth in a closed system is characterized by four phases:
(1) In the initial lag phase, no growth occurs as the organisms adapt to the new environment.
(2) In the exponential, or log phase, the organisms grow at the fastest rate and antibiotics that interfere with cell growth or division are most likely to be effective.
(3) In the stationary phase, when nutrients have been largely exhausted, organisms tend to stop growing but may remain viable for long periods of time.
(4) In the phase of decline, cell deaths increase due to cell starvation or exposure to toxins.

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25>The correct answer is C. The single finding of high autoantibody titers to histones, without any other autoantibodies, is characteristic of drug-induced lupus. The most commonly implicated drugs are procainamide, hydralazine (given for hypertension), and isoniazid. Patients typically have milder disease than in SLE, and tend to have arthritis, pleuro-pericardial involvement, and, less commonly, rash. CNS and renal disease are not usually observed.
CREST syndrome (choice A) is a milder variant of scleroderma characterized by calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly and telangiectasia. Anti-centromere antibodies are diagnostic.
The diffuse form of scleroderma (choice B), also known as systemic sclerosis, causes fibrosis of the skin and internal viscera. This disorder is characterized by anti-SCI-70 and often low titers of many other autoantibodies.
Sjِgren's syndrome (choice D) is characterized by dry eyes and dry mouth. Sjِgren's syndrome in isolation is characteristically positive for anti-SSA and anti-SSB. If it accompanies rheumatoid arthritis, anti-RNP will be positive as well.
Systemic lupus erythematosus (choice E) is a multisystem disorder that is distinguished from drug-induced lupus by the presence of a wide variety of autoantibodies, including anti-double stranded DNA (anti-dsDNA).
--------------------------------------------------------------------------------

26>The correct answer is D. The disease is rheumatoid arthritis, and the autoantibody is rheumatoid factor, which is usually an IgM or IgG (or less commonly IgA) directed against the constant region of autologous IgG.
Autoantibody directed against acetylcholine receptor (choice A) is a feature of myasthenia gravis.
Autoantibody directed against double stranded DNA (choice B) is a feature of systemic lupus erythematosus.
Autoantibody directed against histones (choice C) is a feature of drug-induced lupus.
Autoantibody directed against ribonucleoprotein (choice E) is a feature of mixed connective tissue disease.

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27>The correct answer is C. The drug of choice for otitis media in children is amoxicillin. But in refractory cases, often due to bacterial resistance, switching to a different drug class is often effective. You must look for another medication that is effective against common organisms responsible for pediatric otitis media, such as Streptococcus pneumoniae (a gram-positive diplococcus) and Haemophilus influenzae (a gram-negative rod). A second-generation cephalosporin, such as cefaclor, should cover both and is the best choice. Consequently, it is commonly used in cases of amoxicillin-resistant otitis media. None of the other choices cover the proper spectrum of organisms.
Amphotericin B (choice A) is an antifungal polyene. It works by binding to ergosterol in the fungal cell membrane, creating an artificial pore. It is used to treat systemic mycoses such as Aspergillus, Blastomyces, Candida, Coccidioides, Cryptococcus, and Histoplasma.
Bacitracin (choice B) is a topical agent used to fight infection with gram-positive organisms. It interferes with cell wall synthesis.
Erythromycin (choice D) is a macrolide antibiotic that binds to the 23s rRNA portion of the 50s subunit of ribosomes, inhibiting release of uncharged tRNA and stopping protein synthesis. Though effective against S. pneumoniae, it is not particularly active against H. influenzae. Note that erythromycin may be used in amoxicillin-resistant otitis media, but only when administered with a sulfonamide such as sulfisoxazole.
Sulfamethoxazole (choice E) is a sulfonamide. It is bacteriostatic and works by inhibiting folic acid synthesis. It resembles p-aminobenzoic acid (PABA) structurally. When combined with trimethoprim (a dihydrofolate reductase inhibitor) it exerts a bactericidal effect and serves as the drug combination of choice for complicated urinary tract infections.

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28>The correct answer is C. Neuroleptic malignant syndrome (NMS) is a potentially fatal condition that can occur at any time during the course of treatment with neuroleptics. The exact etiology is unknown. Excessive muscle contraction produces muscular rigidity, and is also responsible for the high temperature. The obtunded mental state and mutism is characteristic. Muscle relaxants, such as dantrolene, and dopamine agonists, such as bromocriptine, are used in the treatment of NMS.
Acute dystonia (choice A, prolonged contractions of muscle groups), akathisia (choice B, "restless legs" ), and parkinsonism (choice D, pill-rolling tremor and rigidity) are all extrapyramidal side effects that occur early during neuroleptic treatment.
Tardive dyskinesia (choice E) is a late-appearing complication of neuroleptic therapy characterized by perioral and athetoid movements.

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29>The correct answer is E. Spore formation usually occurs during the stationary phase, when cell growth ceases because of a developing lack of nutrients or accumulation of toxins.
During the phase of decline (choice A), the lack of nutrients and the accumulation of toxin become so severe that any viable organisms usually die before they can form spores.
The exponential phase (choices B) and log phase (choice D) are descriptors for the steady state of active growth occurring after the lag phase and before the stationary phase. Many antibiotics are most effective in this period.
The lag phase (choice C) is the initial period of adaptation, prior to growth, which occurs when organisms are introduced to a new environment.
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30>The correct answer is D. This is a case of Streptococcus pneumoniae meningitis. This organism is able to attach to the respiratory mucosa because it has teichoic acids in its envelope, and because it produces an IgA protease. The IgA protease physically cleaves the immunoglobulin molecules, leaving the Fc parts to coat the bacterium. This allows the organisms to bind to the Fc receptors on various mucosal cells.
Streptococcus pneumoniae does not produce a C carbohydrate (choice A), and thus cannot be grouped by the Lancefield terminology.
Although the organism does produce the pneumolysin, which is an alpha-hemolytic exotoxin (choice B), this toxin mediates damage to the respiratory epithelium and inhibition of leukocytic responses, not attachment to the mucosa.
Streptococcus pneumoniae does not produce an hyaluronic acid capsule (choice C); Streptococcus pyogenes does. Most capsules serve to inhibit phagocytosis, rather than to mediate adhesion.
Only the group A Streptococci possess an M protein (choice E), which is used to "type" them and helps inhibit phagocytosis.
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31>The correct answer is E. This patient has Sjِgren's syndrome, which is an autoimmune disease characterized by lymphocytic infiltration of exocrine glands resulting in dry mouth (xerostomia) and dry eyes (keratoconjunctivitis sicca). Patients have an increased risk of malignant lymphoma. Autoantibodies produced include anti-Ro (SS-A), anti-La (SS-B), antinuclear antibodies, and rheumatoid factor.
Choice A: Anti-centromere antibodies are a very specific marker for CREST syndrome. Rheumatoid factor is usually positive in rhe

Usmle-mcq's-6

2008-03-17T08:21:00.000-07:00

1>A 25-year-old male presents to his family physician with the following
statement: "Doctor, I can't urinate in public restrooms. I can if
there is no one around, but if I go to the restroom in a movie, an
airport, at the ball park or anywhere that someone else comes in,
I can't urinate. Even if I have already started, it just stops and
I can't get it going until the other person leaves. I am so
embarrassed. What do they think of me if they see I can't
do what every other man can do?" Which of the following
is the most likely diagnosis?
A. Anxiety disorder due to a general medical condition
B. Panic disorder
C. Social phobia
D. Specific phobia
E. Substance-induced anxiety disorder

Answer
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2>Autopsy of an elderly individual who died in a nursing home with no
known genetic diseases reveals small amounts of amyloid deposition
in the heart. Amyloid deposition is not seen in other organs. There
is no history of long-standing inflammatory disease. This type of
amyloid would be most likely to be composed of which of the
following proteins?
A. Amyloid-associated protein
B. Amyloid light chain protein
C. Beta-2-amyloid protein
D. Beta-2-microglobulin
E. Transthyretin
Answer
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3>A family is referred to a genetic specialist because of mild mental
retardation in several of the school-age children. Laboratory evaluation
demonstrates a specific chromosomal breakage site in metaphase studies
of lymphocytes cultured with methotrexate. Which of the following
chromosomes is most likely to be specifically affected?
A. X
B. Y
C. 13
D. 16
E. 21
Answer
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4>A 5-year-old male with no previous medical history is brought to the
ER by his mother because he accidentally ingested a large dose of rat
poison. He is conscious but appears quite agitated. On physical exam,
he is found to have a blood pressure of 110/70 and a heart rate of 90.
Labs are significant for an elevated PT but a normal PTT. The patient
should be immediately treated with
A. atropine
B. flumazenil
C. N-acetylcysteine
D. protamine
E. vitamin K
Answer
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5>A 67-year-old man is evaluated for persistent shooting pains, lower
limb ataxia, and bladder dysfunction. Physical examination demonstrates
small irregular pupils that constrict with accommodation but not in
response to light. A VDRL test is positive. A CT scan of the spinal
cord would most likely demonstrate atrophy of which of the following
structures?
A. Dorsal column
B. Dorsal horn
C. Lateral column
D. Ventral column
E. Ventral horn
Answer
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6>What is the earliest age at which toilet training is likely to be
successful?
A. 10 months
B. 13 months
C. 16 months
D. 19 months
E. 22 months
Answer
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7>A 13-year-old boy is brought to a rural clinic because of poor school
performance. His parents state that he did not begin talking until after
three years of age, and still does not use language as effectively as
his sister, who is 6-years-old. A careful family history reveals that
a maternal grandfather was mildly retarded. The mother has two sisters,
both of whom are apparently normal, but the mother admits that she did
not do well in school, and dropped out at the age of 16. Physical
examination of the child reveals large ears, a long, narrow face,
and large testes. Which of the following genetic mechanisms most
likely accounts for the observed findings in the son?
A. Expanded trinucleotide repeat
B. Genomic imprinting
C. Robertsonian translocation
D. Trisomy 13
E. Trisomy 18
Answer
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8>A 15-year-old is brought to the emergency department in a coma. An alert
ambulance attendant notes that the patient's breath smells like acetone.
This would be most consistent with which of the following?
A. Alcohol intoxication
B. Diabetic hyperosmolar coma
C. Diabetic ketoacidosis
D. Heroin overdose
E. Profound hypoglycemia
Answer
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9>A 28-year-old male with history of mood disorder presents with a decreased
need for sleep, irritability, recklessness, and increased energy. Which of
the following is the most likely additional presenting symptom?
A. Depressed mood
B. Fear of dying
C. Insomnia
D. Racing thoughts
E. Recurrent thoughts and actions that relieve anxiety when
carried out
Answer
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10 A 10-year-old girl who is a suspected victim of child abuse
is referred to a psychologist for evaluation. As part of her
workup, the patient is asked to construct a story based on pictures
. Which of the following psychometric measures was utilized?
A. Minnesota Multiphasic Personality Inventory
B. Myers-Briggs Personality Inventory
C. Rorschach Test
D. Thematic Apperception Test
E. Type A and B Behavior Patterns Test
Answer
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11>
A 65-year-old woman has a long-standing dementing disorder characterized
by deterioration in personality, neglect of personal hygiene, impaired
judgment, and disinhibited behavior. MRI demonstrates severe cortical
atrophy limited to the frontal lobes and anterior two thirds of the
temporal lobes, while the remaining cortex is preserved. No evidence
of recent or remote infarcts is found. Which of the following diagnoses
is most consistent with these pathologic and clinical features?
A. Alzheimer disease
B. Creutzfeldt-Jacob disease
C. Dementia with Lewy bodies
D. Frontotemporal dementia
E. Vascular dementia
Answer
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12>
A 50-year-old woman who works as a paralegal in a law firm comes to her
local doctor because of problems with sleep. The patient says that over
the past several weeks, she hasn't slept well, feels tired, and has had
headaches. She does not smoke or drink alcohol, except on special
occasions, and does not take any medications. The patient's pupils
are 5 mm in size, equal and reactive, with both the direct and
consensual light reflexes intact. Accommodation is unimpaired.
Examination of the visual fields and funduscopy are unremarkable.
Extraocular movements reveal normal conjugate, oblique, and
downward movement, but she is unable to look upwards. No other
abnormalities are found on the neurological examination. Which
of the following is the most likely diagnosis?
A. Acoustic neuroma
B. Astrocytoma in the cerebellum
C. Craniopharyngioma
D. Parasagittal meningioma
E. Pinealoma
Answer
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13>A one-year-old baby presents with increasing flaccid paralysis, lack
of coordination, and hyporeflexia. Over the next several years, the
child's condition deteriorates to a bedridden vegetative state.
Funduscopic examination reveals optic atrophy. Extensive enzymological
studies document a deficiency of arylsulfatase A (cerebroside sulfatase)
in leukocytes. Which of the following is the most likely diagnosis?
A. Gaucher's disease
B. Krabbe's disease
C. Metachromatic leukodystrophy
D. Niemann-Pick disease
E. Tay-Sachs disease
Answer
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14>A 60-year-old male executive with a history of angina pectoris and
depression had bypass surgery the previous day. His depression has
responded well to selective serotonin reuptake inhibitors (SSRIs)
and there is no history of psychosis in the past. He now presents
with confusion, agitation, irritability, and tries to remove his
IV lines. His level of consciousness fluctuates, and at times he
forgets who he is. He is given a neuroleptic drug, and appears
much improved. What is the most likely diagnosis?
A. Adjustment disorder
B. Delirium
C. Dementia
D. Exacerbation of depression with suicidal ideation and
psychotic features
E. Schizophrenia
Answer
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15>A 38-year-old woman with a history of multiple sexual partners is most
at risk for which of the following?
A. Bladder carcinoma
B. Cervical carcinoma
C. Endometrial carcinoma
D. Ovarian carcinoma
E. Rectal carcinoma
Answer
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16>Which of the following chemotherapeutic agents is specific for the M
phase of the cell cycle?
A. Cytarabine
B. Daunorubicin
C. Hydroxyurea
D. Mechlorethamine
E. Vincristine
Answer
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17>A 47-year-old man with a history of type 2 diabetes, depression, and
hypertension presents to the emergency department with spontaneous
priapism. Which of the following drugs is the most likely cause of
his current condition?
A. Atenolol
B. Furosemide
C. Glyburide
D. Paroxetine
E. Trazodone
Answer
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18>Tay-Sachs disease, an autosomal recessive disease caused by a deficiency
of hexosaminidase A, is lethal in childhood. In a population of Ashkenazi
Jews, blood testing shows the frequency of heterozygotes to be 0.1. What
is the probability that the first child of two individuals from this
population with no family history of the disease will have Tay-Sachs?
A. 0.25
B. 0.11
C. 0.0625
D. 0.0025
E. Cannot be calculated from the information given
Answer
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19>A 44-year-old male with a history of polysubstance abuse presents with
nausea, vomiting, increased heart rate, high blood pressure, sweating,
agitation, and weakness. He also complains of seeing monsters on the
wall during the interview. Which of the following best accounts for
this presentation?
A. Alcohol intoxication
B. Alcohol intoxication or cocaine withdrawal
C. Alcohol withdrawal
D. Alcohol withdrawal or cocaine intoxication
E. Cocaine intoxication
F. Cocaine withdrawal
Answer
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20>In which of the following laboratory tests would you expect to find the
greatest disparity in reference intervals between men and (non-pregnant)
women?
A. Mean corpuscular volume
B. Serum alkaline phosphatase
C. Serum ferritin
D. Serum glucose
E. Serum sodium
Answer
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21>A 7-year-old girl is walking across a vacant lot and steps on a nail. The
next day, her foot is sore and the wound appears inflamed. During these
early stages of infection, which of the following compounds exert the
most powerful chemotactic effect on neutrophils, causing them to migrate
into the inflamed area?
A. C5a and IL-8
B. IL-1 and tumor necrosis factor
C. LTC4 and LTD4
D. PGI2 and PGD2
E. Thromboxane and platelet activating factor
Answer
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22>A 23-year-old woman with a history of sickle cell disease presents with
fever and severe bone pain localized to her left tibia. X-ray reveals a
lytic lesion and blood cultures reveal infection. A bone culture grows
gram-negative rods. Which of the following best describes the infecting
organism?
A. It is a facultative intracellular parasite
B. It is a nonmotile facultative anaerobe
C. It is comma-shaped and sensitive to acidic pH
D. It is motile and does not ferment lactose
E. It is motile and oxidase positive
Answer
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23>A 17-year-old girl loses her best friend in an automobile accident. After
the death, she starts writing for hours daily in her diary. This would
most likely be an example of which of the following defense mechanisms?
A. Identification
B. Projection
C. Rationalization
D. Regression
E. Sublimation
Answer
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24>Physical examination of a neonate demonstrates abnormal facies with a
small lower jaw, low-set ears, and a prominent occiput. The feet have a
rocker-bottom deformation, and the infant is hypertonic. Cardiac
evaluation demonstrates a ventricular septal defect. Which of the
following is the average life-span for infants with this neonate's
syndrome?
A. 2-3 months
B. 1-2 years
C. 4-7 years
D. 15-25 years
E. Normal life expectancy
Answer
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25>A biopsy of a brain tumor from a 42-year-old man reveals a glial neoplasm
consisting of atypical astrocytes with scattered mitoses. Besides mitotic
activity, which of the following markers can provide information about
the neoplasm's proliferative activity?
A. bcl-2
B. Glial fibrillary acidic protein (GFAP)
C. Ki-67
D. p53
E. Ubiquitin
Answer
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26>A pharmacologist is determining the pharmacokinetic parameters of a novel
antibiotic in order to determine the proper dosage. The drug is a
weak organic acid with a pKa of 3.0. Assuming a pH of 2.0 in the
stomach, approximately what percent of the drug will be in a form
that can be rapidly absorbed from the stomach?
A. 0.1
B. 1
C. 10
D. 50
E. 90
F. 99
Answer
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27>A 38-year-old woman vacationing in Connecticut is bitten by a tick.
She does not seek medical treatment and eventually develops chronic
arthritis of the knee and hip joints and paralysis of the left facial
muscles. A physical examination during the early stages of the disorder
would most likely have revealed
A. aphthous ulcers in the mouth
B. erythema chronicum migrans
C. flaccid paralysis of limb flexors
D. purpuric lesions in a bathing trunk distribution
E. spastic paralysis of limb extensors
Answer
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28>A 20-year-old man with new onset of seizures and no history of hypertension
is evaluated with a contrast-enhanced CT scan of the head, which
demonstrates a mixed parenchymal and subarachnoid hemorrhage. The
parenchymal hemorrhage is centered over one cerebral hemisphere.
Which of the following is the most likely source of the hemorrhage?
A. Arteriovenous malformation
B. Berry aneurysm
C. Bridging vein
D. Charcot-Bouchard aneurysm
E. Middle meningeal artery
Answer
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29>A baby is born with a small head, small eyes, and 6 fingers on each hand.
Two dimensional echocardiography reveals congenital heart defects.
Which of the following genetic conditions is most likely to be the
cause of this child's presentation?
A. Trisomy 13
B. Trisomy 18
C. Trisomy 21
D. XXY
E. XYY
Answer
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30>A 35-year-old male presents to an infectious disease specialist with
recurrent infections with encapsulated bacterial organisms. The history
indicates that these infections have become apparent in the last
6 months. Laboratory findings indicates that the total immunoglobulin
level exceeded 900 mg/dL with a low CH50 (hemolytic complement) level.
Which of the following is the correct diagnosis?
A. Acquired hypogammaglobulinemia (common variable hypogammaglobulinemia)
B. C3 deficiency
C. Hyper-IgM syndrome
D. Wiskott-Aldrich syndrome
E. X-linked infantile hypogammaglobulinemia
Answer
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31>A researcher develops a specific antibody to the complement component C3b
. Assume that intravenous administration of the antibody prevents the
biological effects of C3b. Administration of the antibody would be
expected to interfere with which of the following biological functions?
A. Decreased appetite
B. Fever
C. Increased collagen synthesis by fibroblasts
D. Increased leukocyte adherence to endothelium
E. Opsonization to facilitate phagocytosis
Answer
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32>A 42-year-old man previously diagnosed with kidney stones complains
of gnawing, burning epigastric pain. On questioning, he also notes
moderate to severe diarrhea. Measurement of the patient's basal gastric
acid output reveals that it is markedly elevated. These symptoms are
likely the result of which of the following neoplastic syndromes?
A. Familial polyposis coli
B. MEN I
C. MEN IIA
D. MEN IIB
E. MEN III
Answer
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33>During the isolation of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) from
post-mortem human brain tissue, researchers find that the peptide
is rapidly degraded by peptidases in 1 minute at 37 C. Detailed
analysis of the peptide cleavage pattern of Met-enkephalin is
investigated with two candidate enzymes. Using the drug bestatin,
the investigators found no detectable Tyr-Gly-Gly-Phe-Met but did
find significant concentrations of Tyr-Gly-Gly. Using thiorphan,
there was no detectable Tyr-Gly-Gly-Phe-Met, but there was a
high concentration of Tyr. Which of the following is the best
conclusion about Met-enkephalin metabolism that can be drawn
from these data?
A. Bestatin inhibits an aminopeptidase, and thiorphan inhibits an endopeptidase in the degradative pathway
B. Bestatin inhibits a carboxypeptidase in the degradative pathway
C. Bestatin inhibits an endopeptidase in the degradative pathway
D. Thiorphan inhibits an aminopeptidase, and bestatin inhibits an endopeptidase in the degradative pathway
E. Thiorphan inhibits an aminopeptidase in the degradative pathway
Answer
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34>The pharmacokinetic properties of a new drug are being studied in
normal volunteers during phase I clinical trials. The volume of
distribution and clearance determined in the first subject are
40 L and 2.0 L/hour, respectively. The half-life of the drug
in this subject is approximately
A. 2 hours
B. 6 hours
C. 14 hours
D. 21 hours
E. 40 hours
Answer
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35>The pregnant mother of a 6-year-old son with glucose-6-phosphate
dehydrogenase deficiency is very worried that her female fetus
will have the disease. The father and mother are clinically normal.
Which of the following is true about her baby?
A. The baby has a 25% chance of clinical disease
B. The baby has a 50% chance of being a carrier
C. The baby has a 50% chance of clinical disease
D. The baby will be a carrier
E. The baby will have clinical disease
Answer
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36>Medical students at a major teaching hospital are routinely assigned
to observe obstetric patients and to assist during delivery. When a male
medical student introduces himself to an obstetric patient, the patient
becomes agitated and requests that no students be present during her
delivery. The patient had been informed, prior to admission, that this
was a teaching hospital and that a student would be assigned to her
case. When informed of the patient's refusal, the attending physician
in charge should
A. ask the patient's husband for his consent
B. assign a female medical student to observe
C. not allow any medical students to observe this patient
D. have the patient's nurse seek permission
E. have the student approach the patient again and explain the necessity for student observation
F. have the student observe in the background as a part of the health care team.
G. meet with the patient and discuss the value of observation in medical training
Answer
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37>A 24-year-old migrant farm worker is rushed to a nearby emergency room
after an accidental exposure to parathion. He is in respiratory distress
and is bradycardic. Which of the following drugs can be given to increase
the activity of his acetylcholinesterase?
A. Atropine
B. Deferoxamine
C. Dimercaprol
D. N-acetylcysteine
E. Physostigmine
F. Pralidoxime
Answer
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38>A 74-year-old woman with multiple myeloma is being treated with high
doses of doxorubicin (Adriamycin). She has also received
cyclophosphamide and prednisone recently. During his examination,
the physician should check the patient for
A. abdominal tenderness
B. bladder distention
C. limitation of movement
D. papilledema
E. pulmonary rales
Answer
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39>A 60-year-old man hospitalized with metastatic colon cancer signs a
DNR order. This means that the medical staff treating him is required
to
A. discontinue narcotic pain medication
B. not attempt CPR in case of cardiac arrest
C. refrain from prescribing future medications
D. withhold parenteral nutrition and IV fluid hydration
Answer
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40>A 27-year-old swimmer who feels insecure about her athletic abilities
harshly criticizes her teammates' techniques. Which of the following
ego defense mechanisms is she displaying?
A. Displacement
B. Projection
C. Reaction formation
D. Repression
E. Sublimation
Answer
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41>In a certain population, the frequency of color-blind males is 1 in 100.
Assuming that the population is in Hardy-Weinberg equilibrium at this
locus, the frequency of color-blind females is approximately
A. 0.0001
B. 0.0005
C. 0.01
D. 0.02
E. 0.025
Answer
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42>A newborn presents with severe acidosis, vomiting, hypotonia, and
neurologic deficits. Serum analysis reveals elevated levels of lactate
and alanine. These observations suggest a deficiency in which of the
following enzymes?
A. Alanine aminotransferase
B. Glutamate dehydrogenase
C. Lactate dehydrogenase
D. Pyruvate carboxylase
E. Pyruvate dehydrogenase
Answer
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43>A 5-year-old boy who has been diagnosed with a mucopolysaccharidosis is
given an IQ test and found to have nearly normal intellectual functioning.
Which of the following are possible diagnoses for this patient?
A. Hunter syndrome or Hurler syndrome
B. Hunter syndrome or Scheie syndrome
C. Hurler syndrome or Sanfilippo syndrome
D. Morquio syndrome or Sanfilippo syndrome
E. Morquio syndrome or Scheie syndrome
Answer
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44>A 72-year-old female patient with Alzheimer's disease, but no other
medical problems, suddenly becomes comatose and dies due to an intracranial
hemorrhage that caused severe damage to her entire left cerebral
hemisphere. There was no evidence or history of trauma. What is the
most
likely cause of this hemorrhage?
A. Epidural hematoma
B. Subdural hematoma
C. Amyloid angiopathy
D. Rupture of berry aneurysm
E. Rupture of Charcot-Bouchard aneurysm
Answer
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45>A 23-year-old man living in a group home for the developmentally
challenged has an IQ of 73. He does not read or write, and communicates
with one or two word utterances. He will not interact with other group
home members, and since birth he has "pulled back" and becomes agitated
when others get physically close to him. In his room, everything is in
a given place; if any of his belongings are moved, he becomes quite
disturbed. Which of the following is the most likely diagnosis?
A. Asperger's disorder
B. Autistic disorder
C. Childhood disintegrative disorder
D. Obsessive compulsive disorder
E. Schizophrenia, catatonic
Answer
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46>Which of the following amino acids is most responsible for the buffering
capacity of hemoglobin and other proteins?
A. Arginine
B. Aspartic acid
C. Glutamic acid
D. Histidine
E. Lysine
Answer
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47>Addition of which of the following exhaustively 14C labeled substrates
would lead to evolution of 14CO2 from a cell-free suspension containing
all the enzymes and substrates required for the synthesis of uridylic
acid?
A. Aspartate
B. Carbamoyl phosphate
C. Glutamine
D. Glycine
E. N10-Formyltetrahydrofolate
Answer
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48>A 54-year-old college professor is diagnosed with colon cancer and has
it resected. Tumor is found extending from the mucosa to the serosal
surface of the colon and in three regional lymph nodes. Histological
examination demonstrates that the tumor is composed of cells with
ovoid, relatively small nuclei that form well-defined glands. Which
of the following best describes this tumor?
A. High stage, high grade
B. High stage, low grade
C. Low stage, high grade
D. Low stage, low grade
Answer
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49> A 52-year-old man presents to his physician after a community health
screening test reveals a fasting glucose of 170 mg/dL. Physical
examination is remarkable for bronze skin pigmentation, hepatomegaly,
splenomegaly, and limitation of motion in the second and third
metacarpophalangeal joints of both hands. A liver biopsy obtained
from the patient is shown above. The man has no known history of
hemolytic anemia, and takes daily multivitamins without minerals.
Which of the following pigments is most likely present in the
man's liver?
A. Bilirubin
B. Carotene
C. Ferritin
D. Lipofuscin
E. Melanin
Answer
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50> Which of the following enzymes is located at arrow 1 in
the electron micrograph above?
A. Carnitine acyltransferase II
B. Fatty acyl CoA synthetase
C. Glucose-6-phosphate dehydrogenase
D. Hexokinase
E. Pyruvate kinase
Answer
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Answers
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(39)

1 The correct answer is C. In the condition described, a person is in a social situation and fears that he or she will not be able to perform in the same manner as most everyone else can. The two most common social phobias concern public speaking and restroom performance (sometimes called "shy bladder".)
Anxiety disorder due to a general medical condition (choice A) is diagnosed when a medical condition precipitates anxiety, e.g., hypoglycemia.
Panic disorder (choice B) is characterized by sudden paroxysms of anxiety. It can strike unexpectedly in uncued situations so it would not occur only when others are present.
Specific phobias (choice D) are unreasonable fears of some identifiable thing, not situation (e.g., elevators).
Substance-induced anxiety disorder (choice E) is diagnosed when anxiety is precipitated by ingestion of a psychoactive substance, e.g., hallucinogens.
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2The correct answer is E. This patient has senile cardiac amyloidosis, which is usually a clinically insignificant condition due to deposition of structurally normal transthyretin (formerly called prealbumin). The transthyretin is a normal serum protein used to transport thyroxin and retinal. In addition to causing senile cardiac amyloidosis, transthyretin, in a mutant rather than normal form, is deposited as amyloid in the familial amyloid polyneuropathies.
Amyloid-associated protein (choice A) is a more common protein deposited as amyloid, and precipitates in secondary amyloidosis associated with underlying chronic inflammatory conditions.
Amyloid light chain protein (choice B) is a common protein deposited as amyloid, and precipitates in amyloidosis related to multiple myeloma and other monoclonal B cell proliferations.
Beta-2-amyloid protein (choice C) is deposited as amyloid in the brain (notably in blood vessels and cerebral plaques) of patients with Alzheimer's disease.
Beta-2-microglobulin (choice D) is a normal serum protein that is deposited in amyloidosis complicating long-term hemodialysis.
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3The correct answer is A. The heritable mental retardation condition associated with chromosomal breakage is fragile X syndrome. The break point is at q27.3 on the X chromosome. The test for this condition involves culturing lymphocytes in either folate-deficient medium or with chemical agents such as methotrexate that tend to break chromosomes. To make the diagnosis, at least 4% of metaphase chromosomes must show the specific break-point on the X chromosome. The percentage of defective X-chromosomes above 4% does not correlate well with the degree of mental retardation. The breakage point is a site of CGG trinucleotide repeats, which tend to expand in successive generations, producing the clinical feature of worsening mental retardation in each generation.
Y chromosome (choice B) damage is not part of fragile X syndrome, but loss of this chromosome is one mechanism of producing 45, X0 (Turner syndrome), characterized by mental retardation.
Trisomy 13 (choice C, Patau syndrome), trisomy 16 (choice D, Edward's syndrome) and trisomy 21 (choice E, Down's syndrome) are all associated with mental retardation, but not chromosomal breakage syndromes.
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4The correct answer is E. As you might have guessed from his elevated PT level, the active ingredient in rat poison is warfarin. It acts as an anticoagulant by interfering with the normal hepatic synthesis of the vitamin K-dependent clotting factors II, VII, IX, and X. The most important adverse effect of warfarin is bleeding. The action of warfarin can be reversed with vitamin K.
Atropine (choice A) is used as an antidote for anticholinesterase toxicity (e.g., ingestion of organophosphates).
Flumazenil (choice B) is used as an antidote for benzodiazepine toxicity (e.g., Valium).
N-acetylcysteine (choice C) is used as an antidote for acetaminophen toxicity.
Protamine (choice D) is used as an antidote for heparin overdose. Note that heparin enhances the activity of antithrombin III, producing its anticoagulant effect. Heparin toxicity would have resulted in an elevated PTT.
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5The correct answer is A. The patient has tabes dorsalis, which is a form of neurosyphilis seen 10 to 25 years or longer after primary disease. The pupils described are Argyll Robertson pupils, and are considered diagnostic for neurosyphilis. Characteristically, the dorsal columns, which contain the ascending tracts for sensory information, become atrophic, probably as a result of damage to the dorsal root ganglion cells.
The dorsal gray horn (choice B) contains neurons that respond to sensory input.
The lateral column (choice C) contains both descending (e.g., lateral corticospinal, rubrospinal) and ascending (e.g., spinocerebellar, spinothalamic) tracts.
The ventral column (choice D) contains both descending (e.g., anterior corticospinal, tectospinal) and ascending (e.g., spinothalamic) tracts.
The ventral horn (choice E) contains lower motor neurons.
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6The correct answer is D. Toilet training is not possible before the age of 18 months because the long nerve fibers have not yet myelinated and sphincter control is not possible. Toilet training should be completed by 4 years of age.
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7The correct answer is A. The features described are typical of the familial form of mental retardation known as fragile X syndrome. This disorder is the second most common heritable cause of mental retardation, second only to Down syndrome. Striking features of this disease are that the clinical features tend to worsen with each successive generation, and that males are usually much more severely affected than females, although nearly 50% of carrier females are at least slightly mentally retarded. The explanation appears to involve a region of DNA on the X chromosome that normally contains 6-54 tandem repeats of the sequence CGG. Carrier females for fragile X syndrome may have up to 200 CGG repeats. Clinically affected individuals have 250-4,000 repeats of the CGG sequence. The greater the number of repeats, the more severe the retardation tends to be. Amplification of premutations to full mutations appears much more likely to occur during oogenesis than spermatogenesis.
Genomic imprinting (choice B) is a phenomenon in which the phenotypic expression of a gene differs if the gene is inherited from the mother, rather than the father. An example of this effect is Angelman ("happy puppet") syndrome, caused by a deletion of band q12 in the maternal copy of chromosome 15. A similar deletion in the paternal chromosome 15 produces a different disease called Prader-Willi syndrome.
A Robertsonian translocation (choice C) causes about 5% of cases of Down syndrome. Generally the mother [typically with genotype 45, XX, -14, -21, +t(14q; 21q)] has normal mentation, but some of her children may carry the translocation in addition to the normal maternal chromosome 21 and normal paternal chromosome 21, producing partial trisomy 21. This form of Down syndrome can appear to be a recessive genetic disease.
Trisomy 13 (Patau syndrome; choice D) is characterized by microcephaly, mental retardation, cleft lip and palate, polydactyly, and rocker-bottom feet. Survival is rare beyond one year.
Trisomy 18 (Edwards syndrome; choice E) is characterized by mental retardation, micrognathia, low-set ears, cardiac defects, renal defects, and rocker-bottom feet. Survival is rare beyond one year.
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8The correct answer is C. The smell of acetone on the breath of a comatose patient is an important, rapid diagnostic clue that strongly suggests ketoacidosis and is usually seen in patients with poorly controlled type 1 diabetes. Other features of diabetic ketoacidosis include high blood glucose, increased serum osmolality, hypovolemia, acidosis, and electrolyte imbalance.
In alcohol intoxication (choice A), the breath will smell like alcohol.
Diabetic hyperosmolar coma (choice B) usually is seen in older patients with type 2 diabetes and is not characterized by ketoacidosis. Since there is no acetone production, there is no specific scent to the breath.
In heroin overdose (choice D), no acetone production occurs and there is no specific scent to the breath.
In hypoglycemic coma (choice E), which can occur in diabetics with insulin overdose, no acetone production occurs and there is no specific scent to the breath.
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9The correct answer is D. The presentation suggests a manic or hypomanic episode of a mood disorder. Patients in a manic episode often have an elated or euphoric mood and racing thoughts. Other symptoms of mania include increased energy, hypersexuality, grandiosity, and increased talkativeness. In some patients, irritability, rather than euphoria, is characteristic.
Depressed mood (choice A) can include anhedonia, decreased self-esteem, energy, concentration, appetite, and libido, as well as increased guilt and sucidality.
An unreasonable fear that one might die (choice B) may be associated with panic disorder. Neurovegetative symptoms including severe anxiety, palpitation, shortness of breath, chest pain, trembling, and paresthesias may also occur.
Despite poor sleep, manic patients do not complain of insomnia (choice C). Their need for sleep is decreased. During depressive episodes, patients complain of insomnia or hypersomnia.
Obsessive-compulsive disorder is characterized by distressing recurrent thoughts (obsession) and actions (compulsion) (choice E) that relieve anxiety when carried out.
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10>***
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11The correct answer is D. Not all dementing disorders manifest with the same clinical features. Although there is considerable overlap in clinical symptomatology among different types of dementias, making clinical diagnosis somewhat problematic, there are classic presentations that allow identification of a specific form of dementia with a high degree of confidence. In this case, the patient has symptoms due to frontal lobe damage, eg, disinhibition, impaired judgment, and personality changes. Furthermore, MRI demonstrates a specific pattern of cortical atrophy, restricted to the frontal lobes and anterior portion of the temporal lobes. This combination points toward a group of dementias called frontotemporal dementia, the most frequent form of which is Pick disease. Other forms of frontotemporal dementia are very infrequent. Remember: frontal symptoms in conjunction with frontotemporal atrophy = frontotemporal dementia/Pick disease.
Alzheimer disease (choice A) is the most frequent form of dementia in industrialized countries. Although symptoms due to frontal damage may be present in Alzheimer disease, they are usually associated with a more generalized impairment of higher neurologic functions, eg, language, memory, and learned movements. In addition, cortical atrophy in Alzheimer disease is widespread and not limited to the frontal and anterior temporal lobes.
Creutzfeldt-Jacob disease (choice B) represents the prototype of prion diseases. Cortical atrophy is not a prominent feature of Creutzfeldt-Jacob disease, which manifests with personality changes, memory loss, and seizures, leading to death after a rapid clinical course (a few months to 1 year).
Dementia with Lewy bodies, also known as diffuse Lewy body disease (choice C), is one of the most common forms of dementia in Western countries, possibly more common than vascular dementia. It is characterized by widespread formation of Lewy bodies in the substantia nigra, limbic cortex, and subcortical nuclei, such as the basal nucleus of Meynert. Extrapyramidal symptoms similar to Parkinson disease manifest in this form of dementia as a result of degeneration of dopaminergic pathways.
Vascular dementia (choice E) is an umbrella term encompassing dementing conditions that arise from pathology of large or small cerebral vessels. It manifests with memory loss associated with focal neurologic symptoms depending on the location of damage. MRI would identify old or recent infarcts, as well as white matter disease. Conditions associated with vascular dementia include the following:
Multi-infarct dementia, which is caused by multiple, scattered brain infarcts secondary to atherosclerosis of large arteries of the circle of Willis and/or carotid arteries.
Binswanger disease, which involves rarefaction of cerebral white matter and is caused by hypertension-related arteriolosclerosis.
Lacunar infarcts, which consist of small (< 1 cm) infarcts in the striatum and thalamus; this condition is related to arteriolosclerosis.
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12The correct answer is E. This patient has a pinealoma. Tumors of the pineal gland compress the vertical gaze center in the tectum of the midbrain. The pineal gland manufactures melatonin from its precursor serotonin; an inadequate supply of melatonin results in insomnia. Tumors of the pineal gland will not compress the cerebral cortex or the rest of the brainstem. Frequently, the only physical sign noted is failure of upward gaze.
An acoustic neuroma (choice A) is a schwannoma of the eighth cranial nerve. It results in deafness, ataxia, and dysarthria. Nystagmus may be present. The gaze centers are not affected.
Astrocytomas of the cerebellum (choice B) are usually seen in children. These tumors present with headache, nausea, vomiting, papilledema, and cerebellar signs such as ataxia, dysarthria, nystagmus, and intention tremor. The gaze centers are not affected.
Craniopharyngiomas (choice C) are usually seen in children. There is failure of growth, headaches, and bitemporal hemianopia.
Parasagittal meningiomas (choice D) usually result in headache, spastic paresis, and urinary incontinence
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13The correct answer is C. There are a number of hereditary sphingolipidoses that have devastating clinical courses. In practice, these diseases may have a variable course and may be difficult to specifically diagnose reliably on clinical grounds alone. The most useful clue to the specific diagnosis in this case is the comment about the deficient arylsulfatase A. Deficiency of this enzyme produces metachromatic leukodystrophy, characterized by accumulation of cerebroside sulfates (galactosyl sulfatide). The cerebroside sulfates accumulate as intra- and extracellular spherical masses that stain metachromatically (purplish rather than bluish) with acid cresyl violet, particularly in the nervous system. The biochemical diagnosis can be made by evaluating cultured cells from a variety of sources, including leukocytes, fibroblasts, and hair bulbs. The most common presentation is that described in the question stem; adolescent and adult variants also occur.
Gaucher's disease (choice A) is a sphingolipidosis caused by deficient beta-glucocerebrosidase.
Krabbe's disease (choice B) is a sphingolipidosis caused by deficient beta-galactocerebrosidase.
Niemann-Pick disease (choice D) is a sphingolipidosis caused by deficient sphingomyelinase.
Tay-Sachs disease (choice E) is a sphingolipidosis caused by deficient hexosaminidase A (alpha subunit).
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14The correct answer is B. Delirium is a common complication of general anesthesia and surgery. It is manifested by acute changes in mental status with waxing and waning level of consciousness, agitation, irritability, and psychosis. Patients usually respond to low-dose neuroleptics to achieve sedation. The course is self-limited.
Any psychosocial or biological stressor can lead to adjustment disorder (choice A). This patient's surgery will restrict his level of functioning, at least in the short term. This will be difficult for a high-functioning individual to accept. Adjustment disorder may present with depressive mood, anxiety, and irritability, but a fluctuating level of consciousness is not a feature of this disorder.
Dementia (choice C) can present with irritability, confusion, and agitation, but usually has an insidious course and affects mainly cognition. In contrast to delirium, it does not have a fluctuating course.
Severe depression can present with irritability, suicidal ideation, and psychotic features (choice D). The patient has a history of depression that responded well to SSRIs and he has no prior history of psychosis. He was motivated to undergo cardiac surgery, so removing his IV lines is unlikely to be a manifestation of suicidal ideation.
Schizophrenia (choice E) presents with bizarre behavior, hallucinations, and delusions. It usually starts at a younger age than the acute symptoms in this patient, and is characterized by progressive deterioration in functioning. It is unlikely for a schizophrenic to achieve the functional level of an executive.
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15The correct answer is B. In a sense, cervical carcinoma can be considered a "sexually transmitted disease," since human papilloma virus (typically strains HPV-16 or HPV- 1 is transmitted venereally. In our culture, HPV-related dysplasia of the cervix is common, even in the 18-28 year old group, and carcinomas of the cervix (more rare now than in the past due to screening and aggressive therapy of dysplasia) can occur in the 35-45 age group. The other cancers listed typically occur in older age groups and are not as clearly related to venereal agents.
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16The correct answer is E. Vincristine (and vinblastine) are Vinca alkaloids that bind to tubulin, a component of cellular microtubules. This leads to disruption of the mitotic spindle apparatus and results in metaphase arrest since the chromosomes are unable to segregate. Since these drugs interfere with mitosis, they are considered cell-cycle specific for the M phase.
Cytarabine (choice A) belongs to the class of antineoplastics that are antimetabolites. This drug class interferes with normal metabolic pathways by competing for enzymatic sites. Specifically, cytarabine (Ara-C) is a pyrimidine nucleoside analog. It interrupts DNA synthesis and function by inhibiting DNA polymerase and incorporating into the DNA or RNA of the cell. As you would expect, this drug is cell-cycle specific for the S phase.
Daunorubicin (choice B) is one of the antibiotic antineoplastic agents (others include dactinomycin, doxorubicin, bleomycin, plicamycin, and mitomycin). These agents work by disrupting DNA functioning. Daunorubicin binds to DNA between base pairs on adjacent strands, resulting in uncoiling of the helix and destruction of the DNA template. While this drug has its maximum effect during the S phase, it is not cell-cycle specific. (Note: the only antibiotic that is cell-cycle specific is bleomycin.)
Hydroxyurea (choice C) works by interfering with ribonucleoside diphosphate reductase, the enzyme responsible for generating the deoxyribonucleotides needed for DNA synthesis. It is S-phase specific.
Mechlorethamine (choice D) is a nitrogen mustard. The nitrogen mustards (mechlorethamine, cyclophosphamide, melphalan, chlorambucil) belong to the larger class of alkylating agents. These agents work by alkylating DNA (along with RNA and proteins). The alkylating agents are generally NOT cell-cycle specific.
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17The correct answer is E. Priapism is characterized by the development of a painful erection for an extended period of time. When untreated, priapism can cause severe penile damage that can culminate in impotence. Administration of the antidepressant drug trazodone has been associated with priapism in a number of patients. In patients with prolonged or inappropriate penile erection, this medication should be discontinued and medical attention should be sought immediately. Injection of alpha-adrenergic stimulants, such as norepinephrine or epinephrine, may be successful in treating the priapism. Surgical intervention is necessary for the treatment of trazodone-induced priapism in many instances.
Atenolol (choice A) is a beta-1 adrenergic antagonist indicated for the treatment of hypertension. This agent is commonly associated with impotence in males.
Furosemide (choice B) is a loop diuretic indicated for the treatment of edema and hypertension; electrolyte abnormalities are the most common side effects seen with this agent.
The sulfonylurea glyburide (choice C) is an oral hypoglycemic agent indicated for the treatment of type 2 diabetes; hypoglycemia is the most common side effect of this agent.
Paroxetine (choice D) is a selective serotonin reuptake inhibitor (SSRI) used for the treatment of depression. This agent is commonly associated with impotence in males.
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18The correct answer is D. Since Tay-Sachs is lethal in childhood, the only adults carrying the gene are heterozygotes. The only mating that will produce progeny with the disease is the mating between two heterozygotes. Using the blood test data, the probability that a random individual is a heterozygote is 0.1. The probability that two heterozygotes will produce a child with Tay-Sachs disease is 0.25. So, the overall probability that two individuals in the population will produce a child with Tay-Sachs is (0.1)(0.1)(0.25), or 0.0025.
Choice A, 0.25, could be obtained if the parents are carriers, so the probability of a Tay-Sachs child is equal to the probability that two heterozygotes will produce a child with the disease, or 0.25.
Choice B, 0.11, could be obtained if both of the parents had a sibling with Tay-Sachs. This would mean that the grandparents must have carried the disease, and that their normal children had a 0.67 chance of carrying the allele. This gives the probability that the parent's child would have Tay-Sachs as (0.67)(0.67)(0.25), or 0.11.
Choice C, 0.0625, is also incorrect. It is the product of (0.25)(0.25).
Choice E incorrectly assumes that because q2, the frequency of the disease, cannot be calculated, and hence the allele frequencies cannot be calculated, that an estimate of the frequency of heterozygotes cannot be made. The problem can be done, however, because the heterozygote frequency (0.1) was given in the question stem.
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19The correct answer is D. This man's presentation can be explained either by alcohol withdrawal or by cocaine intoxication. Nausea, vomiting, sympathetic nervous system activation, and weakness could be produced in either case. Visual hallucinations (seeing monsters) can also be accompanied by tactile and auditory hallucinations. In severe cases, either alcohol withdrawal or cocaine intoxication can cause convulsions.
Alcohol intoxication (choice A and B) is characterized by disinhibition, aggression, impaired attention and judgment, unsteady gait and imbalance, slurred speech, nystagmus, and a decreased level of consciousness.
Other symptoms associated with alcohol withdrawal (choices C and D) include insomnia, headache, and tremors of the tongue, eyelids, and outstretched hands.
Withdrawal from cocaine (choices B and F) is characterized by dysphoria, lethargy, psychomotor retardation or agitation, increased appetite, sleep disturbances, and bizarre or unpleasant dreams.
Other symptoms associated with cocaine intoxication (choices D and E) include grandiosity, paranoid ideation, and pupillary dilatation. Orientation usually remains intact.
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20The correct answer is C. Men have higher reference intervals than women in tests related to iron and hemoglobin (Hb) concentration in blood. The normal reference interval for Hb concentration in women is lower (12.0-16.0 gm/dL) than that for men (13.5-17.5 gm/dL) due to lower serum testosterone levels (testosterone is higher in men and stimulates erythropoiesis) and blood loss during menses. Furthermore, women normally have about 400 mg of iron (as ferritin) in their bone marrow iron stores versus an average of 1000 mg of iron for men. In the absence of inflammation, the small circulating fraction of ferritin (choice C) correlates well with ferritin stores in the bone marrow. Hence, men have different reference intervals for serum ferritin than do women (15-200 ng/mL in men versus 12-150 ng/mL in women).
The mean corpuscular volume (choice A), serum alkaline phosphatase (choice B), serum glucose (choice D), and serum sodium (choice E) are similar in both sexes.
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21The correct answer is A. The most important chemotactic factors for neutrophils are the complement factor C5a and the interleukin IL-8.
The cytokines IL-1 and tumor necrosis factor (choice B) have complex, similar actions, including stimulation of production of many acute-phase reactions, stimulation of fibroblasts, and stimulation of endothelium.
Leukotrienes LTC4 and LTD4 (choice C) cause increased vascular permeability.
Prostaglandins PGI2 and PGD2 (choice D) mediate vasodilation and pain.
Thromboxane and platelet activating factor (choice E) induce platelet changes
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22The correct answer is D. The presence of sickle cell disease in a question stem is usually a significant clue. This question tests if you know that patients with sickle cell anemia are more susceptible to osteomyelitis caused by Salmonella. (The patient's fever, bone pain, and x-ray results indicate osteomyelitis). But note that Staphylococcus aureus (gram-positive coccus) is the most common cause of osteomyelitis in both sicklers and nonsicklers. If it had not been ruled out on bone culture, you should have looked for it in the answer choices. Notice that you were required to know more than just the organism's name; you needed to know its distinguishing features. Choice D describes Salmonella (a gram-negative rod) accurately. Salmonella exists in over 1800 serotypes and is known to contaminate poultry.
A facultative intracellular parasite (choice A) is Legionella, a catalase-positive gram-negative rod. It contaminates air-conditioning cooling towers and causes Legionnaire's disease (a type of pneumonia).
A nonmotile, facultative anaerobe (choice B) is Shigella, a gram-negative rod that does not produce H2S. All Shigella contain an endotoxic lipopolysaccharide. The organism causes bacillary dysentery, with abdominal cramps, fever, and mucoid, bloody diarrhea.
A comma-shaped organism that is sensitive to acidic pH (choice C) is Vibrio cholerae, a gram-negative rod that causes severe enterotoxin-induced diarrhea, with "rice-water" stools and dehydration. The toxin acts by stimulating adenylyl cyclase to overproduce cAMP in the brush border of the small intestine.
A motile and oxidase positive organism (choice E) is Pseudomonas, a gram-negative rod with pili that sometimes produces a polysaccharide slime layer. P. aeruginosa is the prototype and commonly colonizes the lungs of patients with cystic fibrosis. It is associated with blue-green pus.
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23The correct answer is E. Sublimation is the diversion of unacceptable impulses into more acceptable ones. In this case, the girl would like to continue to talk to her best friend, but since that is not possible, she substitutes writing in her diary. An example of sublimation seen fairly frequently in medical settings is the mother whose child died of a disease who becomes active in a state or national organization designed to help families with the disease.
Identification (choice A) is the adoption of characteristics or activities of another person.
Projection (choice B) occurs when someone attributes their own thoughts to a different person.
Rationalization (choice C) is the offering of a false, but acceptable, explanation for behavior.
Regression (choice D) is the adoption of behavior more appropriate to a younger age.
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24The correct answer is A. The syndrome described is Edwards' syndrome (trisomy 1, which is typically characterized by the features noted and additionally causes severe mental retardation, which would not be recognizable in the neonatal period. This disease is relatively common, with an incidence of about 1 in 5000 births (Down syndrome has an incidence of 1 in 2000 births). The average life span is only 2-3 months.
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25The correct answer is C. Ki-67 is a nuclear factor (of uncertain function) whose expression correlates with neoplastic replicative activity. Its expression can be visualized by immunostaining of formalin-fixed, paraffin-embedded sections. Ki-67 labeling correlates with a neoplasm's rate of growth and, therefore, with prognosis.
The bcl-2 gene (choice A) suppresses apoptosis by different mechanisms. Its abnormal activation is involved in the pathogenesis of low-grade lymphomas but not astrocytomas.
GFAP (choice B) is an intermediate cytoskeletal filament (analogue of keratin and vimentin) expressed exclusively by certain types of glial cells, e.g., astrocytes and ependymal cells. Immunohistochemistry for GFAP is used diagnostically to confirm an astrocytic origin of a neoplasm, but gives no information about mitotic or proliferative rate.
The gene p53 (choice D) encodes a protein that blocks the cell cycle when damage to DNA occurs. If the damage is successfully repaired, p53 allows the cell cycle to resume; if not, p53 induces apoptosis, thus eliminating dangerous DNA mutations. Mutations of p53 have been found in the great majority of human neoplasms, including gliomas. However, its expression gives no information concerning neoplastic replicative activity.
Ubiquitin (choice E) is a low-molecular-weight heat-shock protein. Its function is to tag aberrant proteins for degradation. It is present in many abnormal intraneuronal inclusions associated with neurodegenerative disorders, such as Lewy bodies, Pick bodies, and neurofibrillary tangles. It has no relationship with mitotic activity or growth rate.
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26The correct answer is E. First, it is necessary to know that it is the uncharged, lipid-soluble form that can be rapidly absorbed. For an acid: HA <-------> H+ + A-. Therefore, the protonated form is uncharged. The Henderson-Hasselbalch equation is:
pH = pKa - log[protonated form/unprotonated form]
In this case,
2.0 = 3.0 - log [HA/A-]
1.0 = log [HA/A-]
10 = HA/A- = 10/1
HA/(HA + A-) = 10/(10 + 1) = 91%, or approximately 90%
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27The correct answer is B. Lyme disease should be suspected in a patient who is bitten by a tick in the northeastern U.S. Lyme disease was named after a township in eastern Connecticut where the disease was endemic. The disease is spread via a tick vector of the genus Ixodes, which transmits a spirochete that causes a systemic illness. Erythema chronicum migrans is usually the first sign of the illness. This is a large red patch on the buttocks or chest that slowly expands as the center blanches. Generally, patients also have constitutional symptoms, such as fever and chills, during this phase. Stiff neck may develop, along with other signs of meningeal irritation, because of an aseptic meningitis. Other neurologic complications of Lyme disease include Bell's palsy due to involvement of branches of the facial nerve. Arthritis is a prominent feature in about half the patients with Lyme disease. It tends to appear several months after the infection but may persist for several years. The course of the chronic arthritis shows exacerbations and remissions; the most commonly affected joints are the knees and hips. Cardiac abnormalities in Lyme disease include pericarditis and heart block.
Skin manifestations do not include aphthous ulcers (choice A).
Flaccid or spastic paralysis of limbs (choices C and E) does not accompany Lyme disease; neurologic involvement is generally limited to cranial nerves and meningitis.
Purpura (choice D) is associated with vasculitis and does not occur in Lyme disease.
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28The correct answer is A. Arteriovenous malformations are composed of complex tangles of congenitally malformed vessels that typically involve the superficial or deep cerebral hemispheres. There is a slight male predominance, and bleeding typically occurs in adolescence or young adulthood. Symptoms may be those of subarachnoid hemorrhage (headache, increased intracranial pressure) and/or seizures. Surgical resection is usually required for therapy.
Berry aneurysms (choice B) can produce both subarachnoid and parenchymal hemorrhage, but are usually centered near the base of the brain.
Bleeding from bridging veins (choice C) causes subdural hematoma.
Charcot-Bouchard aneurysms (choice D) are small, intraparenchymal aneurysms that are related to hypertension.
Rupture of the middle meningeal artery (choice E) causes epidural hematoma.
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29The correct answer is A. This is Patau syndrome, or trisomy 13. This disorder is also associated with severe mental retardation, abnormal forebrain structures, and death within one year of birth. Patau syndrome has an incidence of 1:6000 births, making it the second most common form of autosomal trisomy.
Trisomy 18 (choice B) is Edwards syndrome, characterized by severe mental retardation, rocker bottom feet (also sometimes seen in Patau syndrome, so be careful!), low-set ears, micrognathia, clenched hands, prominent occiput, and death within one year. Edwards syndrome has an incidence of 1:8000, making it the third most common autosomal trisomy.
Trisomy 21 (choice C) is Down syndrome, and is characterized by mental retardation, flat facial profile, prominent epicanthal folds, simian crease, duodenal atresia, and congenital heart disease. Down syndrome is the most common autosomal trisomy, with an incidence of 1:700.
XXY (choice D) is Klinefelter syndrome and is associated with male hypogonadism and infertility, eunuchoid body habitus, gynecomastia, and lack of male secondary sexual characteristics.
XYY (choice E) is double Y syndrome.

Usmle-mcq's-6

2008-03-17T08:20:00.002-07:00

1A 10-year-old male presents to the pediatrician because of problems
while eating. He can chew food but has problems swallowing the chewed
pieces, and feels them in his throat. A radiographic study is performed
that shows normal musculature but abnormal esophageal peristalsis. No
masses are seen. Which of the following nerves should be tested for
abnormalities?
A. Hypoglossal and phrenic
B. Hypoglossal and splanchnic
C. Glossopharyngeal and vagus
D. Phrenic and vagus
E. Splanchnic and vagus
Answer
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2A 40-year-old man with adult polycystic kidney disease is brought to
the emergency room in a coma. CT scan of the head demonstrates a
subarachnoid hemorrhage without parenchymal hemorrhage. Which of
the following is the most likely source of the bleeding?
A. AV malformation
B. Bridging veins
C. Charcot-Bouchard aneurysm
D. Circle of Willis
E. Middle meningeal artery
Answer
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3An unconscious patient with sepsis in the intensive care unit
undergoes a 2-hour period of severe hypotension. Blood chemistries
taken during the following 48 hours show rising creatine kinase MB
fraction (CK-MB), peaking at 5 times the upper limit of normal. ECG
findings are equivocal, with some degree of flat S-T segment
depression over several leads. Which of the following is the
most likely diagnosis?
A. Prinzmetal angina
B. Stable angina
C. Subendocardial infarction
D. Transmural infarction
E. Unstable angina
Answer
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4A 65 year-old man is admitted to the coronary care unit with a
diagnosis of a large myocardial infarct (MI) of the left ventricle.
On his 6th postinfarct day, he goes into shock and dies, manifesting
signs and symptoms of cardiac tamponade. Which of the following
complications is the most likely cause of this patient's death?
A. Aortic dissection
B. Extension of previous MI
C. Fatal arrhythmia
D. Rupture of the left ventricular wall
E. Rupture of papillary muscle
Answer
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5A newborn appears normal at birth, but develops vomiting and diarrhea
accompanied by jaundice and hepatomegaly within the first few weeks of
life. Within months, the baby has obvious cataracts and ascites. The
infant is switched to a milk-free diet, which stabilizes but does not
completely reverse his condition. By one year of age, he has developed
mental retardation. Which of the following is the most likely diagnosis?
A. Cystic fibrosis
B. Galactosemia
C. McArdle's disease
D. Von Gierke's disease
E. Wilson's disease
Answer
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6A 25-year-old man presents with headache, dizziness, and claudication.
Blood pressure measurements reveal hypertension in the upper limbs and
hypotension in the lower limbs. Which of the following additional
findings would be most likely in this case?
A. Aortic valvular stenosis
B. Notching of inferior margins of ribs
C. Patent ductus arteriosus
D. Pulmonary valvular stenosis
E. Vasculitis involving the aortic arch
Answer
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7A patient has a tiny (0.2 cm), but exquisitely painful tumor under
the nail of her index finger. Prior to surgery to remove it, local
anesthetic block to a branch of which of the following nerves would
be most likely to achieve adequate anesthesia?
A. Axillary nerve
B. Median nerve
C. Musculocutaneous nerve
D. Radial nerve
E. Ulnar nerve
Answer
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8Tissue from a spontaneous abortion is submitted to the laboratory,
where an astute pathologist notes the presence of mature fetal tissue
that contains Barr bodies. The fetus may have had which of the following
genotypes?
A. Classic Turner syndrome (45, X)
B. Edward's syndrome (47, XY+1
C. Klinefelter's syndrome (47, XXY)
D. Normal male (46, XY)
E. XYY syndrome (47, XYY)
Answer
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9A 78-year-old woman is brought to the emergency department because of
slowly developing confusion over the past ten days. Careful physical
examination demonstrates a relatively small laceration of the scalp.
CT of the head would be most likely to reveal which of the following?
A. Epidural hematoma
B. Mixed parenchymal and subarachnoid hemorrhage
C. Multiple tiny hemorrhages of the putamen
D. Subarachnoid hemorrhage
E. Subdural hematoma
Answer
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10A 22-year-old woman presents to her physician with amenorrhea,
weight loss, anxiety, tremor, heat intolerance and palpitations.
Laboratory examination is consistent with hyperthyroidism, and
the physician prescribes propylthiouracil. The patient's response
to propylthiouracil is disappointing, and the symptoms recur,
then worsen. Subtotal thyroidectomy is successfully performed,
but following the surgery, the woman is extremely hoarse, and can
barely speak above a whisper. This hoarseness is most probably
related to damage to a branch which of the following cranial nerves?
A. Facial
B. Glossopharyngeal
C. Hypoglossal
D. Trigeminal
E. Vagus
Answer
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11A 24-year-old female is brought to the emergency room after
threatening to kill herself by cutting her wrists. She has multiple
scars on her wrists, which she admits were caused by prior suicide
attempts. She states she is very angry at her boyfriend, who left her
for another woman. She previously thought her boyfriend was an angel
and now she thinks he is a monster. She feels very empty inside.
While smiling, she states that she is depressed. During the interview,
she drops to the ground, but continues to talk while lying on the floor
. She believes nobody understands her. What is her underlying personality
disorder?
A. Antisocial
B. Borderline
C. Histrionic
D. Narcissistic
E. Schizoid
Answer
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12A high school basketball player passes out in the middle of a game. He
is rushed to the emergency room, where he regains consciousness. He
claims that just before he fainted, he had difficulty breathing and
experienced palpitations. On physical exam, he has a bifid apical
impulse and a coarse systolic murmur at the left sternal border.
The echocardiogram reveals ventricular hypertrophy with asymmetric
septal thickening. Which of the following would increase the intensity
of his heart murmur?
A. Elevating his legs
B. Increasing sympathetic tone
C. Performing the Valsalva maneuver
D. Squatting
Answer
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13A 63-year-old man complains of trouble swallowing and hoarseness. On
physical exam, he is noted to have ptosis and a constricted pupil on
the left, and a diminished gag reflex. Neurological examination shows
decreased pain and temperature sensation on the left side of his face
and on the right side of his body. Which of the following vessels is
most likely occluded?
A. Anterior inferior cerebellar artery (AICA)
B. Anterior spinal artery
C. Middle cerebral artery (MCA)
D. Posterior cerebral artery (PCA)
E. Posterior inferior cerebellar artery (PICA)
Answer
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14Examination, at autopsy, of the brain of a man who died in an intensive
care unit demonstrates bilateral, linear, parasagittal areas of
coagulative necrosis in the junctional zone between the anterior
and medial cerebral arterial systems. Which of the following is
the most likely etiology?
A. Bacterial infection
B. Fungal infection
C. Ischemia
D. Tumor
E. Viral infection
Answer
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15A 55-year-old woman presents to her physician after several episodes
of syncope. Physical examination is remarkable for a
low-pitched "plopping" sound during mid-systole.
Two-dimensional echocardiography demonstrates a
ball-valve type obstruction of the mitral valve.
Which of the following would most likely be observed
if the cause of the obstruction were biopsied?
A. Benign glandular tissue
B. Densely packed smooth muscle
C. Densely packed striated muscle
D. Malignant glandular tissue
E. Scattered mesenchymal cells in a myxoid background
Answer
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16The presence of which of the following features in an atherosclerotic
plaque indicates that it has become a complicated lesion?
A. Cholesterol crystals
B. Chronic inflammatory cells
C. Intimal smooth muscle
D. Lines of Zahn
E. Necrotic cell debris
Answer
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17A 46-year-old woman presents to her physician with "double vision"
and is unable to adduct her right eye on attempted left lateral gaze.
Convergence is intact. Both direct and consensual light reflexes are
normal. Which of the following structures is most likely to be affected?
A. Left oculomotor nerve
B. Medial longitudinal fasciculus
C. Right abducens nerve
D. Right oculomotor nerve
E. Right trochlear nerve
Answer
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18A patient arrives in the emergency room after having suffered severe
head trauma in a motorcycle accident. Radiographic studies of the head
reveal a basilar skull fracture in the region of the foramen ovale.
Which of the following functional losses would most likely be related
to this injury?
A. Loss of abduction of the eye
B. Loss of sensation over the forehead
C. Loss of sensation over the zygoma
D. Loss of taste sensation on the anterior 2/3 of the tongue
E. Paralysis of muscles of mastication
Answer
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19A 64-year-old man has a myocardial infarction, and is hospitalized. He
is seen by a cardiologist, who orders echocardiographic studies, which
demonstrate a portion of the apex of the left ventricle that bulges
outward during systole and inward during diastole. This finding is
most likely related to disease involving which of the following structures?
A. Aortic valve
B. Circumflex artery
C. Left anterior descending artery
D. Mitral valve
E. Tricuspid valve
Answer
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20A mailman gets a severe bite wound from a pit bull guarding a
junkyard. The wound is cleansed and he receives a booster injection
of tetanus toxoid and an injection of penicillin G. Several days later,
the wound is inflamed and purulent. The exudate is cultured on blood
agar and yields gram-negative rods. Antibiotic sensitivity tests are
pending. The most likely agent to be isolated is
A. Bartonella henselae
B. Brucella canis
C. Clostridium tetani
D. Pasteurella multocida
E. Toxocara canis
Answer
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21A 7-year-old boy is referred to a specialty clinic because of
digestive problems. He often experiences severe abdominal cramps
after eating a high fat meal. He is worked up and diagnosed with
a genetic defect resulting in a deficiency of lipoprotein lipase.
Which of the following substances would most likely be elevated
in this patient's plasma following a fatty meal?
A. Albumin-bound free fatty acids
B. Chylomicrons
C. HDL
D. LDL
E. Unesterified fatty acids
Answer
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22A 10-year-old girl who is a suspected victim of child abuse is
referred to a psychologist for evaluation. As part of her workup,
the patient is asked to construct a story based on pictures. Which
of the following psychometric measures was utilized?
A. Minnesota Multiphasic Personality Inventory
B. Myers-Briggs Personality Inventory
C. Rorschach Test
D. Thematic Apperception Test
E. Type A and B Behavior Patterns Test
Answer
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23Which of the following enzymes is located at arrow 1 in the electron
micrograph above?
A. Carnitine acyltransferase II
B. Fatty acyl CoA synthetase
C. Glucose-6-phosphate dehydrogenase
D. Hexokinase
E. Pyruvate kinase
Answer

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24A 22-year-old female college student is brought into the emergency
room by the police, who found her walking back and forth across a busy
street, talking to herself. The young woman appears to be oriented
with respect to person, place, and time. Her first hospital admission
was two months ago for a similar condition. During a psychiatric
interview, she has difficulty concentrating, and seems to hear voices
. A phone call to her sister provides the additional information that
the girl dropped out of school three months ago and has been living on the street. Urine toxicology is negative. This patient is most likely exhibiting the signs and symptoms of
A. schizoaffective disorder
B. schizoid personality disorder
C. schizophrenia
D. schizophreniform disorder
E. schizotypal personality disorder
Answer
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25A 42-year-old man has just been informed that he has poorly
differentiated small cell carcinoma of the lung. When asked if
he understands the serious nature of his illness, the patient
proceeds to tell his physician how excited he is about renovating
his home. This patient is exhibiting
A. denial
B. displacement
C. projection
D. rationalization
E. reaction formation
F. sublimation
Answer
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26An increase in which of the following best explains the mechanism by
which the cardiac output increases in severe anemia?
A. Arteriolar diameter
B. Blood viscosity
C. Peripheral vascular resistance
D. Splanchnic blood flow
E. Tissue oxygen tension
Answer
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27A 2-year-old retarded child is evaluated by a metabolic specialist.
The child's history is significant for failure to thrive and progressive
neurologic deterioration, including deafness and blindness. Physical
examination is remarkable for hepatosplenomegaly, as well as a
cherry-red spot on funduscopic examination. These symptoms are
consistent with a diagnosis of
A. Hunter syndrome
B. Niemann-Pick disease
C. Pompe's disease
D. tyrosinosis
E. von Gierke's disease
Answer
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28An 8-month-old female child is brought to medical attention because
her first four teeth show several discrete, discolored, circumferential
bands that show very little enamel. Excessive levels of which of the
following may have produced this defect?
A. Bilirubin
B. Fluoride
C. Parathormone
D. Thyroid hormone
E. Vitamin C
Answer
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29Which of the following complications is currently the major
limitation to the long-term success of cardiac transplantation?
A. Allograft rejection
B. Graft arteriosclerosis
C. Graft atherosclerosis
D. Opportunistic infections
E. Lymphoma
Answer
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30A child develops a tumor of the cerebellum. Biopsy reveals evidence
of both neuronal and glial differentiation. Which of the following is
the most likely diagnosis?
A. Astrocytoma
B. Glioblastoma multiforme
C. Medulloblastoma
D. Meningioma
E. Oligodendroglioma
Answer
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31A 56-year-old man visits his physician with complaints of complete
exhaustion after mowing the lawn in his small front yard. He also
complains of dizziness, irritability, difficulty sleeping, and loss
of libido. On physical examination, the man's skin, conjunctiva, and
oral mucosa are pale. A blood test indicates the man's hemoglobin is
7 g/dL. Which of the following findings is also likely to be present
in this man?
A. Bradycardia
B. Cyanosis
C. Low stroke volume
D. Warm hands
E. Wide pulse pressure
Answer
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32A 55-year-old man had been in good health since receiving a heart
transplant for severe atherosclerotic disease. Five years after
transplantation, the patient died suddenly, without any premonitory
symptoms, while working in his garden. He had been maintained on
cyclosporin since his transplant. Which of the following complications
would most likely be found at autopsy in the transplanted heart?
A. Allograft rejection
B. Atherosclerosis of coronary arteries
C. Graft vascular disease
D. Hyaline arteriolosclerosis
E. Hyperplastic arteriolosclerosis
Answer
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33An elderly lady is brought to the emergency room after drinking
insecticide that she thought was tea. After her stomach is pumped
, her sense of smell is tested and it is found that she can not
distinguish common smells (e.g., an orange, coffee). CT scan of
the head demonstrates a mass in the olfactory groove area. The
axons likely compressed by this mass project to which of the
following structures?
A. Insula
B. Nucleus ambiguus
C. Post-central gyrus
D. Pre-central gyrus
E. Pyriform cortex
Answer
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34A 27-year-old man develops bilateral parotid gland swelling and
orchitis, and is generally ill with fever of 102° F. Which of the
following substances is most likely to be significantly elevated
in the patient's serum?
A. Alanine aminotransferase (ALT)
B. Amylase
C. Aspartate aminotransferase (AST)
D. Ceruloplasmin
E. Creatine phosphokinase, MB isoenzyme (CPK-MB)

Answer
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35A 55-year-old man presents to the emergency room with crushing
substernal pain and left shoulder pain of 2 hours duration. The
pain is not relieved by sublingual nitroglycerin, and the
electrocardiogram shows ST elevation in several leads. Aspirin
and streptokinase therapy are initiated, and the patient is
admitted to the intensive care unit. The next morning, serum
cardiac enzymes are elevated to 4 times the upper limit of
normal, and the electrocardiographic changes are still
present. Which of the following is the most likely diagnosis?
A. Prinzmetal's angina
B. Stable angina
C. Subendocardial infarction
D. Transmural infarction
E. Unstable angina
Answer
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36Which of the following amino acids is post-translationally
hydroxylated in the cytoplasm of fibroblasts?
A. Cysteine
B. Glycine
C. Proline
D. Serine
E. Tyrosine
Answer
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37Microscopic examination of a cancer cell reveals a cell in an
abnormal telophase in which three clusters of chromosomes are
seen. An abnormality of which of the following would be most
likely to produce this alteration?
A. Chiasma
B. Mitotic spindle
C. Mosaicism
D. Polar body
E. Synapsis
Answer
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38A 58-year-old man with fainting spells and exercise intolerance
is found to have a bicuspid aortic valve with marked aortic stenosis.
Which of the following physical findings would be prominent in this
patient?
A. Diastolic murmur
B. Heave at left parasternal border
C. Loud S2 heart sound
D. Loud S3 heart sound
E. Weak peripheral pulse
Answer
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39A 57-year-old female is found unconscious on her kitchen floor
after having suffered a myocardial infarction. She has pulmonary
edema and distended jugular and peripheral veins. A midsystolic
gallop is heard upon chest auscultation. EKG shows prominent Q
waves in leads II, III, and aVF. Which of the following is
most consistent with the patient's condition?
Preload Cardiac output PAWP CVP Vascular resistance Mixed venous oxygen
A. Increased Decreased Decreased Increased Increased Decreased
B. Increased Increased Decreased Decreased Decreased Increased
C. Increased Decreased Increased Increased Increased Decreased
D. Increased Increased Increased Increased Decreased Decreased
E. Decreased Decreased Increased Decreased Increased Decreased
F. Decreased Increased Decreased Increased Decreased Increased
G. Decreased Decreased Increased Decreased Decreased Decreased
Answer
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40A 48-year-old man complaining of chest pain is brought to the emergency
room. Physical examination followed by echocardiography demonstrates
aortic stenosis. His coronary blood flow is increased. Which of the
following is the most likely explanation for the increased coronary
blood flow in this individual?
A. Decreased left ventricular oxygen consumption
B. Decreased left ventricular pressure
C. Decreased left ventricular work
D. Increased cardiac tissue adenosine concentration
E. Increased cardiac tissue oxygen concentration
Answer
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41A 45-year-old man presents to the emergency department with severe
headache and vomiting. A CT scan shows a well-circumscribed cystic
lesion within the 3rd ventricle; there is no calcium deposition.
The cyst is surgically removed. On histologic examination, the wall
of the cyst consists of a single layer of mucin-producing columnar
epithelium with a ciliated apical surface. Which of the following is
the most likely diagnosis?
A. Colloid cyst
B. Craniopharyngioma
C. Cysticercosis
D. Echinococcus cyst
E. Pilocytic astrocytoma
Answer
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42A 36-year-old female is brought to the emergency room by her husband
who says that she "complained of a severe headache then lost consciousness." She has a history of hypertension and had been on several different medications. The examining physician notes that she is unable to move her arms and legs, but can blink her eyes. When the physician asks her to blink twice if she can hear him, she promptly does so. In which of the following structures is this woman's lesion most likely located?
A. Cervical spinal cord
B. Medulla oblongata
C. Midbrain
D. Pons
E. Thalamus
Answer
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43A 71-year-old man has been in excellent health, and practicing
competently as an attorney. He is brought to the emergency room
following a motor vehicle accident. A workup, including imaging of
the spine, thorax, and head, is negative, but the patient is admitted
for overnight observation. His injuries include several lacerations to
the face and extremities as well as several contusions to the thorax.
Three weeks later, he is admitted to the hospital for confusion. A
neurologic exam is normal except that he is not oriented to time or
place, and can recall only 1 out of 6 objects after 3 minutes. Which
of the following is the most likely diagnosis?
A. Alzheimer's disease
B. Brain metastases
C. Epidural hematoma
D. Normal pressure hydrocephalus
E. Subdural hematoma
Answer
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44A work diagram showing changes in left ventricular volume and pressure
during one cardiac cycle is shown above for a normal heart (diagram A)
and following aortic valvular disease (diagram B). Diagram B shows which
of the following compared to diagram A?
A. Decreased work for a greater stroke volume
B. Decreased work for a lower stroke volume
C. Decreased work for the same stroke volume
D. Increased work for a greater stroke volume
E. Increased work for a lower stroke volume
F. Increased work for the same stroke volume
Answer

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45An 80-year-old woman dies after a long history of progressive memory loss,
apraxia, and recurrent episodes of confusion. In the last months of life
she was bedridden and unable to recognize familiar faces and objects.
The pathologist identifies numerous flame-shaped intracytoplasmic
inclusions in neurons of the neocortex and hippocampus. These
consist of paired helical filaments (PHFs) on electron microscopy.
Which of the following biochemical changes most likely accounts for
the development of PHFs in this condition?
A. Abnormal degradation of amyloid precursor protein (APP)
B. Abnormal phosphorylation of tau
C. Accumulation of advanced glycosylation end (AGE) products
D. Increased expression of APP
E. Precipitation of insoluble a-tubulin
Answer
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46The activity of which of the following enzymes is directly affected by
citrate?
A. Fructose-2,6-bisphosphatase
B. Isocitrate dehydrogenase
C. Phosphofructokinase I
D. Pyruvate carboxylase
E. 6-phosphogluconate dehydrogenase
Answer
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47While a physician is using a water-filled syringe to expel wax from the
ear canal of an elderly patient, the man suddenly faints. This event can
be explained by the fact that the posterior half of the external ear
canal receives sensory innervation from the
A. auricular branch of the vagus nerve
B. auriculotemporal nerve
C. greater auricular nerve
D. lesser occipital nerve
E. vestibulocochlear nerve
Answer
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48Which of the following structures is found only in Gram-negative
microorganisms?
A. Cell envelope
B. Exotoxin
C. Peptidoglycan
D. Periplasmic space
E. Teichoic acids
Answer
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49A scientist wishes to study free radical production under ischemic
conditions. He decides to produce cerebral ischemia by tying off an
artery of the brain. Ligation of which of the following arteries
would be most likely to produce significant ischemic damage?
A. Anterior cerebral artery at its origin from the internal carotid artery
B. Anterior communicating artery
C. Middle cerebral artery at its origin from the internal carotid artery
D. Posterior cerebral artery at its origin from the basilar artery
E. Posterior communicating artery
Answer
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50A 52-year-old woman has long-standing rheumatoid arthritis (RA) and
is being treated with corticosteroids and nonsteroidal anti-inflammatory
drugs (NSAIDs). Which of the following cardiac complications may arise in
this clinical setting?
A. Constrictive pericarditis
B. Dilated cardiomyopathy
C. Hypersensitivity myocarditis
D. Hypertrophic cardiomyopathy
E. Restrictive cardiomyopathy
Answer
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Answers
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1The correct answer is E. The upper 2/3 of the esophagus contains striated muscle. It is derived from the pharyngeal arches and innervated by the vagus nerve (CN X). The lower 1/3 contains smooth muscle from splanchnic mesoderm and is innervated by the splanchnic plexus.
The hypoglossal nerve (choices A and B), or CN XII, moves the tongue.
The phrenic nerve (choices A and D), derived from C3, C4, and C5, innervates the muscle of the diaphragm.
The glossopharyngeal nerve (choice C), or CN IX, functions in taste, swallowing, and salivation, as well as monitoring the activity of the carotid body.
--------------------------------------------------------------------------------
2The correct answer is D. Two relationships are useful in solving this problem. The first relationship is that adult polycystic kidney disease has a specific association with berry aneurysms involving the circle of Willis and its branches. The second relationship is that spontaneous subarachnoid hemorrhages are most often the result of bleeding from berry aneurysms. The berry aneurysms develop at sites of congenital weakness (near branch points) of the relatively unsupported vessels of the circle of Willis.
AV malformations (choice A) tend to produce mixed parenchymal and subarachnoid hemorrhages.
Rupture of bridging veins (choice B) produces a subdural hematoma.
Rupture of Charcot-Bouchard aneurysms (choice C) can be seen with hypertension (which may complicate adult polycystic kidney disease). Such rupture produces intraparenchymal hemorrhage, which if severe, may spread to the subarachnoid space.
Rupture of the middle meningeal artery (choice E) produces epidural hematoma
--------------------------------------------------------------------------------3The correct answer is C. The high serum CK-MB indicates that the patient has sustained an infarction rather than angina. Subendocardial, rather than transmural, infarction is most likely in the setting of known, prolonged severe hypotension, and the equivocal nature of the ECG findings confirms this diagnosis. Subendocardial infarction occurs in settings of generalized poor perfusion complicated by increased demand or transient vasospasm. Subendocardial muscle tissue is especially vulnerable because it is farthest from the arterial supply.
In Prinzmetal angina (choice A) and stable angina (choice B), the CK-MB would not be expected to increase significantly.
Transmural infarction (choice D) is not specifically expected in the setting of shock. It produces characteristic ECG changes that are usually localized (unless a very large infarct has occurred) to a few leads.
In unstable angina (choice E), an increase in cardiac enzymes may be seen, but is usually less than 2 times the upper limit of normal.
--------------------------------------------------------------------------------4The correct answer is D. Rupture of the free left ventricular wall is a frequently fatal complication that may occur in the first week after myocardial infarction (MI). At this stage, the infarcted area is composed of friable necrotic myocardium and early granulation tissue. It is during this crucial phase, therefore, that rupture usually occurs. Blood rushes out, filling the pericardial sac and causing compression of the left ventricle. Cardiac tamponade ensues, and the patient usually dies of acute cardiogenic shock.
Aortic dissection (choice A) is not a complication of MI, although cardiac tamponade may also follow this acute condition when dissection works its way back toward the aortic root. Aortic dissection usually develops in aortas affected by cystic medial degeneration (CMD), which is due to fragmentation of elastic laminae with accumulation of myxoid material in the aortic media. CMD may be either sporadic or associated with Marfan syndrome.
Extension of a previous MI (choice B) may occur in the first few hours or days after MI. It may aggravate or precipitate cardiogenic shock and/or arrhythmias, but it does not cause cardiac tamponade.
Arrhythmias (choice C) are frequent complications of MI and are often fatal, producing cardiac arrest (ventricular fibrillation) or aggravating cardiac dysfunction.
If infarction involves papillary muscles, these may rupture (choice E). This complication is followed by valvular dysfunction and may manifest with signs of mitral regurgitation and acute congestive heart failure.
--------------------------------------------------------------------------------5The correct answer is B. Galactosemia is an autosomal recessive disease caused by a deficiency of galactose-1-phosphate uridyltransferase, which is necessary for the metabolism of the galactose derived from milk lactose. The condition should be suspected in infants with growth failure, cataracts, liver disease, aminoaciduria, and mental retardation. A reducing sugar (galactose) is usually present in the urine. Most of the pathology is related to the toxic effects of galactose-1-phosphate. Treatment involves strict dietary lactose restriction, which consists of more than simply withdrawal of milk products, because lactose is also present in many non-diary foods. Strict adherence to the diet can strikingly alter the course of this disease.
Cystic fibrosis (choice A) is associated with maldigestion, pancreatic disease, and pulmonary disease.
McArdle's disease (choice C) is a glycogen storage disease that selectively affects muscle.
Von Gierke's disease (choice D) is a glycogen storage disease affecting the liver and kidneys.
Wilson's disease (choice E) is a caused by a metabolic abnormality in the handling of copper that can cause cirrhosis and brain damage, and usually presents in adolescence.
--------------------------------------------------------------------------------
6The correct answer is B. The adult form of aortic coarctation is caused by stenosis in the aortic arch just distal to the left subclavian artery. This leads to hypertension proximal to, and hypotension distal to, the stenotic segment. Hypertension in the upper part of the body manifests with headache, dizziness, and other neurologic symptoms. Hypotension in the lower part of the body results in signs and symptoms of ischemia, most often claudication, i.e., recurrent pain due to ischemia of leg muscles. In addition, collateral arteries between the precoarctation and postcoarctation aorta (eg, the intercostal and internal mammary arteries) enlarge and establish communication between aortic segments proximal and distal to stenosis. Enlarged intercostal arteries produce notching of the inferior margins of the ribs, which can be detected on x-ray and is diagnostic of this condition. Remember that the infantile form of aortic coarctation is associated with patent ductus arteriosus, whereas the adult form is not.
Aortic valvular stenosis (choice A) at this age would most likely be caused by a congenitally malformed valve, usually a valve with two cusps or a single cusp. Aortic stenosis manifests with systolic hypotension, recurrent syncope, and hypertrophy/dilatation of the left ventricle. Low systolic pressure is present in the entire body.
The isolated form of patent ductus arteriosus (choice C) leads to shunting of blood from the aorta (high-pressure vessel) to the pulmonary artery (low-pressure vessel). Eventually, chronic cor pulmonale develops with resultant right-sided heart failure.
Pulmonary valvular stenosis (choice D) is a rare form of congenital heart disease that leads to chronic cor pulmonale and heart failure.
Vasculitis involving the aortic arch (choice E) is found in Takayasu arteritis, in which chronic inflammatory changes develop in the aortic arch and its branches (brachiocephalic trunk, left common carotid, and left subclavian arteries). This condition causes stenosis of these arteries; therefore, there will be signs and symptoms of ischemia to the upper part of the body. Since the radial pulses are very weak or absent, this disorder is also known as pulseless disease.
--------------------------------------------------------------------------------7The correct answer is B. The tumor in question is probably a glomus tumor, which is a benign tumor notorious for producing pain far out of proportion to its small size. The question is a little tricky (but important clinically for obvious reasons) because it turns out that the most distal aspect of the dorsal skin of the fingers, including the nail beds, is innervated by the palmar digital nerves rather than the dorsal digital nerves. Specifically, the median nerve through its palmar digital nerves supplies the nail beds of the thumb, index finger, middle finger, and half of the ring finger.
The axillary nerve (choice A), musculocutaneous nerve (choice C), and radial nerves (choice D) do not supply the nail beds.
The radial nerve does supply the more proximal skin of the back of the index finger. The ulnar nerve (choice E) supplies the nail beds of the small and half of the ring finger.
--------------------------------------------------------------------------------8.The correct answer is C. The Barr body, or X chromatin body, is an inactivated X chromosome seen as a small, perinuclear, dark-staining dot in somatic cells with two or more X chromosomes. Barr bodies are seen in any individual born with at least two X chromosomes, including normal females. (47, XXY), the classic karyotype of Klinefelter's syndrome, is defined as male hypogonadism due to the presence of a Y chromosome and two or more X's. As in normal females, one of the X chromosomes becomes a Barr body in Klinefelter's syndrome.
Classic Turner syndrome females (choice A) and genotypically normal males (choice D) have only one X chromosome. Thus, no X chromosome is inactivated, and somatic cells do not show any Barr bodies.
(47, XY+1 is the karyotype of an Edward's syndrome (choice B) fetus. Although this trisomic phenotype is associated with a characteristic syndrome of physical abnormalities, there is no programmed inactivation of the extra chromosome 18. Thus, no Barr body is produced.
XYY syndrome (choice E) is not associated with inactivation of any X chromosomes, so Barr bodies are not present. Like a trisomy involving any of the non-sex-linked chromosomes, the duplicated chromosome is expressed in its entirety.
--------------------------------------------------------------------------------9The correct answer is E. This history is fairly typical for subdural hematoma. Usually, the patient is elderly or alcoholic and has some degree of brain atrophy, causing the brain to pull slightly away from the skull. This stretches the bridging (penetrating) veins that cross the skull to connect to the cranial venous sinuses, leaving them very vulnerable to rupture after minor head trauma. This type of hematoma is due to venous, rather than arterial, hemorrhage and thus tends to develop rather slowly.
Epidural hematoma (choice A) is seen following severe head trauma causing laceration of the middle meningeal artery.
Mixed parenchymal and subarachnoid hemorrhage (choice B) can be seen with bleeding from AV malformations.
Multiple tiny hemorrhages of the putamen (choice C) are intraparenchymal hemorrhages associated with severe hypertension.
Subarachnoid hemorrhage (choice D) can be seen with bleeding from ruptured berry aneurysms.
--------------------------------------------------------------------------------10The correct answer is E. The recurrent laryngeal nerves are branches of the vagus (CN X), and supply all intrinsic muscles of the larynx except the cricothyroid. The right recurrent laryngeal nerve recurs around the right subclavian artery. The left recurrent laryngeal nerve recurs in the thorax around the arch of the aorta and ligamentum arteriosum. Both nerves ascend to the larynx by passing between the trachea and esophagus, in close proximity to the thyroid gland. The recurrent laryngeal nerves are therefore particularly vulnerable during thyroid surgery, and damage may cause extreme hoarseness.
The facial nerve (choice A) innervates the muscles of facial expression, the stapedius muscle, and the lacrimal, submandibular and sublingual glands. It also mediates taste sensation from the anterior two-thirds of the tongue.
The glossopharyngeal nerve (choice B) innervates the stylopharyngeus muscle and the parotid gland. Visceral afferents supply the carotid sinus baroreceptors and carotid body chemoreceptors, and mediate taste from the posterior one-third of the tongue. Somatosensory fibers supply pain, temperature, and touch information from the posterior one-third of the tongue, upper pharynx, middle ear, and eustachian tube.
The hypoglossal nerve (choice C) innervates the intrinsic muscles of the tongue, the genioglossus, hypoglossus, and styloglossus muscles.
The trigeminal nerve (choice D) receives sensory information from the face and also innervates the muscles of mastication.
--------------------------------------------------------------------------------11The correct answer is B. Characteristics of borderline personality disorder include frantic behavior to avoid abandonment, unstable interpersonal relationships, alternating between idealization and devaluation (splitting), recurrent suicidal gestures or other types of self-mutilatory behavior, feelings of emptiness, and inappropriate intense anger.
An antisocial patient (choice A) does not confirm to social norms, is deceitful, impulsive, reckless, irresponsible, and lacks remorse for wrongdoings.
One symptom that would suggest histrionic personality disorder (choice C) in this patient is her theatrical exaggeration of her emotions by talking while lying on the floor. A histrionic patient might present with attention-seeking and/or seductive and provocative behavior, but the presence of splitting, recurrent suicidal gestures and anger argue strongly for the diagnosis of borderline personality disorder.
A narcissistic patient (choice D) is grandiose and preoccupied with success, feels special and requires admiration, feels entitled, takes advantage of others, lacks empathy, and is arrogant.
A schizoid patient (choice E) is usually not interested in relationships or pleasurable activities, is a loner, lacks friends, is emotionally cold, and is indifferent to praise or criticism.
--------------------------------------------------------------------------------12The correct answer is C. This patient has hypertrophic cardiomyopathy-the most common cause of sudden cardiac death in young patients. It usually causes problems during exertion. Clues to the diagnosis include: dyspnea, palpitations, bifid apical impulse, coarse systolic murmur at the left sternal border, and ventricular hypertrophy with asymmetric septal thickening on echocardiogram. Left ventricular outflow obstruction typically plays an important role in the pathophysiology of this condition. Maneuvers that decrease preload, such as the Valsalva maneuver, will accentuate the heart murmur because they result in less ventricular filling, contributing to greater outflow obstruction.
Elevating his legs (choice A), increasing sympathetic tone (choice B), and squatting (choice D) would all increase venous return and would therefore diminish the murmur.
--------------------------------------------------------------------------------13The correct answer is E. The signs and symptoms in this patient are consistent with occlusion of the posterior inferior cerebellar artery (PICA). PICA is a branch of the vertebral artery (which is itself a branch of the subclavian artery). Occlusion of PICA causes a lateral medullary syndrome characterized by deficits in pain and temperature sensation over the contralateral body (spinothalamic tract dysfunction); ipsilateral dysphagia, hoarseness, and diminished gag reflex (interruption of the vagal and glossopharyngeal pathways); vertigo, diplopia, nystagmus, and vomiting (vestibular dysfunction); ipsilateral Horner's syndrome (disruption of descending sympathetic fibers); and ipsilateral loss of pain and temperature sensation of the face (lesion of the spinal tract and nucleus of the trigeminal nerve).
AICA (choice A) is a branch of the basilar artery. Occlusion of this artery produces a lateral inferior pontine syndrome, which is characterized by ipsilateral facial paralysis due to a lesion of the facial nucleus, ipsilateral cochlear nucleus damage leading to sensorineural deafness, vestibular involvement leading to nystagmus, and spinal trigeminal involvement leading to ipsilateral pain and temperature loss of the face. Also, there is ipsilateral dystaxia due to damage to the middle and inferior cerebellar peduncles.
The anterior spinal artery (choice B) is a branch of the vertebral artery. Occlusion produces the medial medullary syndrome, characterized by contralateral hemiparesis of the lower extremities and trunk due to corticospinal tract involvement. Medial lemniscus involvement leads to diminished proprioception on the contralateral side, and ipsilateral paralysis of the tongue ensues from damage to the hypoglossal nucleus.
The MCA (choice C) is a terminal branch of the internal carotid artery. Occlusion results in contralateral face and arm paralysis and sensory loss. Aphasia is produced if the dominant hemisphere is affected, left-sided neglect ensues if the right parietal lobe is affected, and quadrantanopsia or homonymous hemianopsia occur when there is damage to the optic radiations.
The PCA (choice D) arises from the terminal bifurcation of the basilar artery. Occlusion results in a homonymous hemianopsia of the contralateral visual field. Often, there is macular sparing.
--------------------------------------------------------------------------------14The correct answer is C. The distinctive areas of necrosis described in the question stem are border zone (watershed) infarcts. They occur as the result of severe ischemia, which most profoundly affects the relatively poorly perfused areas at the boundaries between major arterial territories. The areas of necrosis described in the question stem are those most commonly observed, although similar infarcts involving border zones in the brain stem are sometimes also seen.
Bacterial infection (choice A) tends to produce either meningitis, cerebritis, or localized infections such abscesses.
Fungal infection (choice B) tends to produce either meningitis, vasculitis, granulomas, or abscesses.
Tumor (choice D) tends to produce localized masses.
Viral infection (choice E) may have a variety of patterns, including meningitis, diffuse encephalitis, or localized necrosis, but would not be expected to produce a distinctive linear pattern.
--------------------------------------------------------------------------------15The correct answer is E. The most common primary cardiac tumor of adults is atrial myxoma, which typically occurs as a single lesion in the left atrium that may intermittently obstruct the mitral valve. Histologically, these tumors are composed of scattered mesenchymal cells in a prominent myxoid background.
Benign glandular tissue (choice A) suggests an adenoma, which is not usually found in the heart.
Densely packed smooth muscle (choice B) suggests a leiomyoma, which is not usually found in the heart.
Densely packed striated muscle (choice C) suggests rhabdomyoma, which is the most common primary cardiac tumor in children, not adults.
Malignant glandular tissue (choice D) suggests carcinoma, which can be metastatic to the heart, but does not usually cause a ball-valve obstruction.
--------------------------------------------------------------------------------16The correct answer is D. Complicated lesions indicate advanced atherosclerotic disease. They arise in atherosclerotic plaques, and render them more susceptible to sudden occlusion and acute infarction of the supplied tissues. Commonly, the plaque ulcerates or ruptures, and the exposed surfaces, being highly thrombogenic, precipitate thrombus formation. Thrombi are typified by the lines of Zahn, alternating layers of platelets and fibrin (the pale lines) and layers of blood (the dark lines). Beyond thrombus formation, other features of a complicated plaque include hemorrhage into the lesion itself, and microembolism by cholesterol crystals or calcified debris. Furthermore, the weakened media underlying the plaque may develop an aneurysmal dilatation. In general, the clinical significance of atherosclerosis is related to the consequences of complicated lesions.
The incorrect options all include features of atheromatous plaques, but do not indicate complicated lesions:
Beneath the endothelium of a plaque there is a fibrous cap composed of smooth muscle (choice C), chronic inflammatory cells (choice B) and lipid laden macrophages (foam cells), as well as extracellular material.
The core of the lesion, which lies between the intima and the media, is composed of necrotic cellular debris (choice E), with cholesterol crystals (choice A), calcium, and more foam cells.
--------------------------------------------------------------------------------
17The correct answer is B. This patient is suffering from internuclear ophthalmoplegia (INO), which is caused by a lesion of the medial longitudinal fasciculus (MLF). The medial longitudinal fasciculus (MLF) connects the oculomotor (III), trochlear (IV), and abducens (VI) nuclei and is essential for conjugate gaze. A lesion in the MLF will result in the inability to medially rotate the ipsilateral eye on attempted lateral gaze. However, a lesion of the motor fibers of the right oculomotor nerve would also lead to the same symptoms. The way to truly distinguish between an INO from a lesion of the medial rectus muscle or a lesion of the motor fibers of CN III is to determine whether the patient can converge her eyes. If the innervation of the medial rectus muscle is interrupted, the patient will not be able to move the ipsilateral eye medially for either conjugate or dysconjugate (convergence) movements. However, if the lesion is in the MLF, this would only affect conjugate movement, and not convergence, asin this patient.
The left oculomotor nerve (choice A) is intact because the light reflexes are normal, and there is no description of any eye movement disorders of the left eye.
A lesion of the right abducens nerve (choice C) would result in paralysis of the lateral rectus muscle. This would lead to an inability to abduct the right eye.
The right oculomotor nerve (choice D) innervates the medial rectus muscle, which would lead to an inability to adduct the right eye when looking toward the left. (CN III also innervates the superior rectus, inferior rectus, and inferior oblique extraocular muscles.) However, a patient with a lesion of this nerve would also be unable to converge. A patient with a lesion of CN III would also be expected to have the affected eye look "down and out" because of the unopposed actions of the lateral rectus and superior oblique muscles, and ptosis resulting from denervation of the levator palpebrae muscle. Additionally, a lesion of the right oculomotor nerve could affect light reflexes and produce mydriasis if the parasympathetic fibers of this nerve were damaged.
The trochlear nerve (choice E) innervates the superior oblique muscle, which depresses, intorts, and abducts the eye. A lesion of this nerve theoretically could produce a slight extorsion of the eye and a weakness of downward gaze. However, a lesion of this nerve often produces only minimal symptoms because of the preserved action of muscles that are innervated by the unaffected oculomotor nerve, and because of a compensatory head tilt.
--------------------------------------------------------------------------------18The correct answer is E. The mandibular nerve passes through the foramen ovale and may be injured by this fracture. The mandibular nerve is responsible for the innervation of all of the muscles of mastication: the masseter, the temporalis, the medial pterygoid, and the lateral pterygoid muscles.
Abduction of the eye (choice A) is produced by the lateral rectus muscle, which is innervated by the abducens nerve. The abducens nerve leaves the cranial cavity and enters the orbit by passing through the superior orbital fissure.
Sensation in the skin over the forehead (choice B) is provided by the ophthalmic division of the trigeminal nerve. The ophthalmic division leaves the cranial cavity and enters the orbit by passing through the superior orbital fissure.
Sensation in the skin over the zygoma (choice C) is provided by the maxillary division of the trigeminal nerve. The maxillary division leaves the cranial cavity and enters the pterygopalatine fossa by passing through the foramen rotundum.
Taste sensation on the anterior 2/3 of the tongue (choice D) is provided by the chordae tympani, a branch of the facial nerve. The facial nerve leaves the cranial cavity and enters the temporal bone by passing into the internal auditory meatus. The chordae tympani leave the temporal bone and enter the infratemporal fossa by passing through the petrotympanic fissure.
--------------------------------------------------------------------------------19The correct answer is C. The motion described is called "paradoxical movement" and occurs when a portion of the ventricular wall is infarcted and can no longer contract during systole. The site of infarction described is in the distribution of the left anterior descending artery.
Valvular disease, including that of the aortic valve (choice A), mitral valve (choice D), or tricuspid valve (choice E) will not cause localized paradoxical movement.
The circumflex artery (choice B) supplies the superior part of the posterior wall of the heart, anastomosing there with the right coronary artery.
--------------------------------------------------------------------------------20The correct answer is D. Pasteurella multocida is a gram-negative rod that is normal flora of the oral cavity of dogs and cats. It often causes a local abscess following introduction under the skin by an animal bite. Most cases occur in children who are injured while playing with a pet.
Bartonella henselae (choice A) is a very small, gram-negative bacterium that is closely related to the rickettsia, although it is able to grow on lifeless media. It is the cause of cat-scratch disease (a local, chronic lymphadenitis most commonly seen in children) and bacillary angiomatosis (seen particularly in AIDS patients). In this latter patient population, the organism causes proliferation of blood and lymphatic vessels causing a characteristic "mulberry" lesion in the skin and subcutaneous tissues of the afflicted individual.
Brucella canis (choice B) is a gram-negative rod that is a zoonotic agent. Its normal host is the dog, but when it gains access to humans, it causes an undulating febrile disease with malaise, lymphadenopathy and hepatosplenomegaly. The normal route of exposure is via ingestion of the organism.
Clostridium tetani (choice C) is a gram-positive spore-forming anaerobic rod. It causes tetanus (a spastic paralysis caused by tetanospasmin, which blocks the release of the inhibitory neurotransmitters glycine and gamma-aminobutyric acid [GABA]). There may be no lesion at the site of inoculation, and exudation would be extremely rare.
Toxocara canis (choice E), a common intestinal parasite of dogs, is a metazoan parasite that causes visceral larva migrans. Young children are most likely to be affected, as they are most likely to ingest soil contaminated with eggs of the parasite
--------------------------------------------------------------------------------21The correct answer is B. After eating a high fat meal, triglycerides are processed by the intestinal mucosal cells. They are assembled in chylomicrons and eventually sent into the circulation for delivery to adipocytes and other cells. Chylomicrons are too large to enter cells, but are degraded while in the circulation by lipoprotein lipase. A defect in this enzyme would result in the accumulation of chylomicrons in the plasma.
Albumin-bound free fatty acids (choice A) is incorrect because fatty acids leave the intestine esterified as triglycerides in chylomicrons.
HDL (choice C) is not a carrier of dietary fat from the intestine.
LDL (choice D) would be not be elevated in this patient after a high fat meal. However, VLDL would be elevated if the patient ate a high carbohydrate meal. In this situation, the carbohydrate would be converted into fat in the liver and sent out into circulation as VLDL. VLDL would be unable to be degraded to LDL and, therefore, would accumulate.
A defect in lipoprotein lipase would cause a decrease, not an elevation of unesterified fatty acids (choice E), since the chylomicrons contain esterified fatty acids.
--------------------------------------------------------------------------------22The correct answer is D. The Thematic Apperception test is a projective test employing pictures depicting ambiguous interpersonal situations that the examinee is asked to interpret. Psychodynamic theory suggests that since the stimuli are vague, the patient projects his or her own thoughts, feelings, and conflicts into his or her responses, providing the examiner insight into the patient's thought and memory content.
The Minnesota Multiphasic Personality Inventory (MMPI; choice A), which uses true and false items, is the most popular objective personality test.
The Myers-Briggs Personality Inventory (choice B) is based on Jungian theory and assesses basic dimensions of personality (extroversion); it is used extensively in occupational counseling. The patient selects preferred adjectives from groups of choices.
The Rorschach Test (choice C) is another projective test that involves asking patients to describe what they see when presented with a series of black and white inkblots.
The Type A and B Behavior Patterns Test (choice E) assesses the amount of "driven quality" a person has to their life. Type A's are always "running out of time." This is a verbal test that resembles an interview.
--------------------------------------------------------------------------------23The correct answer is A. Arrow 1 indicates the inner mitochondrial membrane. Carnitine acyltransferase II is located on the inner face of the inner mitochondrial membrane. It reforms fatty acyl CoA in the mitochondrial matrix (arrow 5) from acyl carnitine, thus preparing it for mitochondrial oxidation. The acyl groups on carnitine are derived from acyl CoA esters synthesized in the outer mitochondrial membrane, which are made from free fatty acids circulating in the blood.
Fatty acyl CoA synthetases (choice B) are located in the outer mitochondrial membrane, indicated by arrow 2.
Glucose-6-phosphate dehydrogenase, the first enzyme in the pentose phosphate pathway (choice C), hexokinase, the first enzyme in the glycolytic pathway (choice D), and pyruvate kinase (choice E), which produces pyruvate from phosphoenolpyruvate in glycolysis, are all located in the cytosol, indicated by arrow 3.
Arrow 4 indicates smooth endoplasmic reticulum.
--------------------------------------------------------------------------------24The correct answer is D. The patient is suffering from schizophreniform disorder. There has been a marked decline in the level of functioning and she was endangering herself in the middle of the street. Schizophreniform disorder is characterized by schizophrenia-like symptoms, but the duration of symptoms is less than six months (but more than one month). Fully developed psychotic symptoms are typical.
In schizoaffective disorder (choice A), alterations in mood are present during a substantial portion of the illness.
Although schizoid personality disorder (choice B) produces detachment from social relationships and is characterized by restriction of emotional expression, it is not accompanied by a marked decline in occupational functioning.
If the symptoms do not remit after six months or more, then the diagnosis of schizophrenia (choice C) should be made.
Schizotypal personality disorder (choice E) is characterized by eccentricities of behavior, odd beliefs or magical thinking, and difficulties with social and interpersonal relationships. Unlike schizophrenia, schizotypal personality disorder is not characterized by a formal thought disorder.
--------------------------------------------------------------------------------25The correct answer is A. This patient is in denial about his serious illness, and by talking about something totally unrelated, he is trying to avoid the bad news he has just received.
Displacement (choice B) involves the transferring of feelings to an inappropriate person, situation, or object (e.g., a man who has been yelled at by his boss takes out his anger on his wife).
Projection (choice C) is the attribution of one's own traits to someone else (e.g., a philandering husband accuses his wife of having an affair).
Rationalization (choice D) involves creating explanations for an action or thought, usually to avoid self-blame.
Reaction formation (choice E) is the unconscious changing of a feeling or idea to its opposite (e.g., a man acts very friendly toward a coworker when in fact he is unconsciously jealous).
Sublimation (choice F) involves turning an unacceptable impulse into an acceptable one (e.g., someone with very aggressive impulses becomes a professional boxer).
--------------------------------------------------------------------------------26The correct answer is A. In severe anemia, diminished transport of oxygen in the blood leads to hypoxia in the tissues. The hypoxia (compare to choice E) causes small arteries and arterioles to dilate, which allows greater-than-normal amounts of blood to return to the heart. In severe anemia, the viscosity of blood (choice B) may decrease by 50% or more because blood viscosity depends largely on the concentration of red blood cells. This decrease in viscosity lowers the resistance to blood flow in the peripheral tissues (i.e., decreases peripheral vascular resistance, choice C) allowing even greater amounts of blood to return to the heart.
Blood is often shunted away from the splanchnic vascular bed (choice D) in anemia, which can cause gastrointestinal problems.
--------------------------------------------------------------------------------27The correct answer is B. Hepatosplenomegaly accompanied by progressive neurologic deterioration should make you think of lipid storage diseases; Niemann-Pick disease is the only lipid storage disease in the answer choices. Niemann-Pick disease is due to a deficiency of sphingomyelinase, leading to an accumulation of sphingomyelin. It is most common among Ashkenazic Jews and generally results in death by age 2. The cherry-red spot is also a characteristic of Tay-Sachs disease, but hepatosplenomegaly suggests Niemann-Pick disease rather than Tay-Sachs.
Hunter syndrome (choice A) is a mucopolysaccharidosis, inherited in an X-linked recessive fashion.
Pompe's disease (choice C) is a glycogen storage disease characterized by hypotonia and cardiorespiratory failure.
Tyrosinosis (choice D) is a rare abnormality of tyrosine metabolism that would not produce the listed symptoms.
von Gierke's disease (choice E) is a severe form of glycogen storage disease characterized by hypoglycemia, hepatomegaly, and renomegaly.
--------------------------------------------------------------------------------28The correct answer is B. Fluoride excess causes direct injury to ameloblasts, leading to inadequate production of tooth enamel. The resultant defect in enamel production causes re

Usmle-mcq's-5

2008-03-17T08:20:00.001-07:00

1>Which of the following conditions may lead to development of an
exudate within the pleural cavity?
A. Bacterial pleuritis
B. Cirrhosis of the liver
C. Congestive heart failure
D. Nephrotic syndrome
E. Protein-losing enteropathy
Answer
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2>In which of the following sites do myxopapillary ependymomas most
frequently occur?
A. Cerebellum
B. Conus medullaris
C. 4th ventricle
D. Lateral ventricles
E. Midbrain
Answer
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3>A patient has long-standing severe hemolytic anemia characterized by
hypochromic cells. Electrophoresis studies demonstrate a near complete
absence of beta chains. Several years later, the patient develops
cardiac failure. Intracardiac deposition of which of the following
would be most likely to contribute to the cardiac failure?
A. Calcium
B. Iron
C. Magnesium
D. Potassium
E. Sodium
Answer
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4>Before being approved by the FDA, a chemical is tested for
carcinogenicity by examining its mutagenic effects on bacterial
cells in culture. Which of the following tests is used to make
this determination?
A. Ames test
B. Nitroblue tetrazolium test
C. Watson-Schwartz test
D. Widal test
E. Woellner enzyme test
Answer
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5.A sharp instrument passing through the superior orbital fissure
would most likely sever the
A. abducens nerve
B. facial nerve
C. mandibular nerve
D. maxillary nerve
E. middle meningeal artery
F. ophthalmic artery
G. optic nerve
Answer
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6>An elderly nursing home patient has had multiple small strokes.
On several occasions she has aspirated food, and neurological
examination reveals that her gag reflex is absent. These findings
suggest involvement of the nucleus of which of the following
cranial nerves?
A. Facial (VII)
B. Glossopharyngeal (IX)
C. Hypoglossal (XII)
D. Spinal accessory (XI)
E. Vestibulocochlear (VIII)
Answer
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7>A new antifungal medication is being tested in Phase I clinical
trials. Examination of the pharmacokinetic properties of the drug
reveals that the half-life of the drug is 6 hours. If a continuous
intravenous infusion of this drug were started on a research subject,
how long would it take to reach 75% of steady state?
A. 3 hours
B. 6 hours
C. 9 hours
D. 12 hours
E. 18 hours
F. 24 hours
Answer
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8>A leukemia patient who has undergone multiple courses of chemotherapy
develops herpes simplex encephalitis. Which of the following would you
expect a CT scan of the patient's brain to show?
A. Generalized volume loss
B. Volume loss selectively in the basal ganglia
C. Volume loss selectively in the brainstem
D. Volume loss selectively in the cerebellum
E. Volume loss selectively in the temporal and frontal lobes
Answer
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9>An 18-year-old male takes an employment physical examination that is
remarkable for a systolic murmur preceded by a distinct click on
auscultation. The patient has unique body features, with unusually
long legs and long, tapering fingers. An ocular examination reveals
dislocation of the lens. An abnormality of which of the following
gene products is thought to underlie this condition?
A. Collagen
B. Dystrophin
C. Elastin
D. Fibrillin
E. Myosin b-chain
Answer
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10>A third-world patient develops muscle weakness and atrophy with
fasciculations and hyporeflexia. The patient's condition continues
to deteriorate, and his legs are eventually permanently paralyzed.
The virus that can cause these problems is usually spread by which
of the following routes?
A. Dirt contact with open wound
B. Injection
C. Mosquitoes
D. Oral-fecal
E. Puncture wound of the foot
Answer
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11>Physical examination of a 45-year-old diabetic patient demonstrates a
pulsatile abdominal mass. Radiographic studies demonstrate a 10 cm
diameter aneurysm of the abdominal aorta with foci of calcification
in the walls. Which of the following is the most likely etiology
for this aneurysm?
A. Atherosclerosis
B. Congenital weakness
C. Cystic medial necrosis
D. Syphilis
E. Vasculitis
Answer
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12>A 40-year-old woman is being seen by a physician for the 10th time
this year for evaluation of vague aches and pains. An extensive prior
evaluation has excluded the possibility of serious disease. During the
interview with this patient, she makes repeated statements along the
lines of, "What I want doesn't matter. Do what you want." And, "I'm
afraid you won't have time to see me anymore." The traits this
patient is exhibiting are most consistent with which of the
following personality disorders?
A. Dependent
B. Histrionic
C. Obsessive-compulsive
D. Paranoid
E. Schizoid
Answer
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13>A 60-year-old man suddenly becomes completely blind in one eye, and
angiography demonstrates occlusion of the central retinal artery.
Which of the following is the most likely cause of the occlusion?
A. Atheroma or embolism
B. Cranial (temporal) arteritis
C. Hypertension
D. Polycythemia vera
E. Tumor
Answer
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14 A mailman gets a severe bite wound from a pit bull guarding
a junkyard. The wound is cleansed and he receives a booster
injection of tetanus toxoid and an injection of penicillin G.
Several days later, the wound is inflamed and purulent. The
exudate is cultured on blood agar and yields gram-negative rods.
Antibiotic sensitivity tests are pending. The most likely agent
to be isolated is
A. Bartonella henselae
B. Brucella canis
C. Clostridium tetani
D. Pasteurella multocida
E. Toxocara canis
Answer
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15.A 7-year-old boy is referred to a specialty clinic
because of digestive problems. He often experiences severe
abdominal cramps after eating a high fat meal. He is worked
up and diagnosed with a genetic defect resulting in a deficiency
of lipoprotein lipase. Which of the following substances would most
likely be elevated in this patient's plasma following a fatty meal?
A. Albumin-bound free fatty acids
B. Chylomicrons
C. HDL
D. LDL
E. Unesterified fatty acids
Answer
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16>A 49-year-old woman is in an automobile accident and sustains a closed
head injury. A CT scan does not show any intracranial hemorrhage, but
reveals a small tumor at the cerebellopontine angle of the brain.
Which of the following nerves is most likely to be affected by
this tumor?
A. Facial nerve
B. Glossopharyngeal nerve
C. Optic nerve
D. Trigeminal nerve
E. Vagus nerve
Answer
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17>A 47-year-old male patient presents with painful arthritis in the
right big toe and uric acid renal stones. He has been taking allopurinol
for his condition. What biochemical defect would likely be found in this
patient?
A. A defect in urea synthesis
B. An abnormality of the purine degradation pathway
C. An inability to synthesize non-essential amino acids
D. Defective topoisomerases
E. Increased levels of leukotrienes
Answer
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18>A 3-year-old boy is brought to the emergency department after the acute
onset of headache, vomiting, nuchal rigidity, and impaired mental status.
MRI reveals a posterior fossa tumor that fills the 4th ventricle. Surgery
is immediately started, and intraoperative consultation leads to
a "frozen section" diagnosis of medulloblastoma. Which of the
following pathologic mechanisms most likely accounts for this
child's clinical presentation?
A. Acute hemorrhage into the 4th ventricle
B. Alteration of medullary function
C. Increased intracranial pressure
D. Infiltration of the cerebellar vermis by the neoplasm
E. Spread of tumor to the subarachnoid space
Answer
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19>A diabetic mother gives birth to a baby who dies in the first week of life.
Autopsy reveals a severe cardiac malformation. Which of the following is
the most likely diagnosis?
A. Atrial septal defect
B. Coarctation of the aorta
C. Eisenmenger's syndrome
D. Tetralogy of Fallot
E. Transposition of the great arteries
Answer
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20>There is a classic zoo story about a cage with three monkeys in it. The
largest monkey steals the middle-sized monkey's banana. The middle-sized
monkey then screams with rage, hits the smallest monkey on the head, and
then steals his banana. The middle-sized monkey is using which of the
following mechanisms of defense?
A. Displacement
B. Projection
C. Reaction formation
D. Regression
E. Repression
Answer
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21>A 10-year-old boy has a small tumor in the wall of the right lateral
ventricle. A biopsy of this tumor is consistent with subependymal giant
cell astrocytoma. Which of the following lesions may also be present in
this patient?
A. Café-au-lait spots
B. Cortical tubers
C. Hemangioblastoma
D. Lisch nodules
E. Schwannoma of the 8th cranial nerve
Answer
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22>Physical examination of a 45-year-old diabetic patient demonstrates a
pulsatile abdominal mass. Radiographic studies demonstrate a 10-cm
diameter aneurysm of the abdominal aorta with foci of calcification
in the walls. Which of the following is the most likely etiology for
the aneurysm?
A. Atherosclerosis
B. Congenital weakness
C. Cystic medial necrosis
D. Syphilis
E. Vasculitis
Answer
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23>A 19-year-old female, who recently moved from her family's home in another
state, is hospitalized for attempting suicide by taking an overdose of
antidepressant medications. On the third day of her hospital stay, she
insists, under threat of a lawsuit, that her medications be stopped and
that she be discharged from the hospital so she "can go home and finish
the job." Her sensorium is clear. Her physician should
A. discharge her against medical advice (AMA)
B. honor her request and release her immediately
C. obtain an emergency order of detention
D. release her to go back to her parents' home
E. sedate her
Answer
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24>Which of the following could prevent an allergen from reacting with a
specific IgE molecule present on the mast cell membrane?
A. Antihistamine
B. Blocking antibody
C. Cromolyn sodium
D. Epinephrine
E. Theophylline
Answer
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25>During a fight, a 32-year-old man is hit on the back of the neck with a
chair. A CT scan reveals a bony fragment that penetrated the lateral
portion of the dorsal columns. Which of the following functions would
most likely be affected by a lesion at this site?
A. Fine motor control of the ipsilateral fingers
B. Motor control of the contralateral foot
C. Sweating of the ipsilateral face
D. Proprioception from the ipsilateral leg
E. Vibratory sense from the ipsilateral arm
Answer
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26>A 40-year-old, formerly obese woman presents to her physician. She was
very proud of having lost 80 lbs. during the previous 2 years, but now
noticed that her "hair is falling out." On questioning, she reports
having followed a strict fat-free diet. Her alopecia is probably related
to a deficiency of which of the following vitamins?
A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin E
E. Vitamin K
Answer
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27>A 50-year-old woman presents with a 5-year history of headaches,
generalized tonic-clonic seizures, and bilateral leg weakness. Skull
films reveal hyperostosis of the calvarium. Biopsy of the responsible
lesion shows a whorling pattern of the cells. Which of the following
is the most likely diagnosis?
A. Arachnoid cyst
B. Glioblastoma multiforme
C. Meningioma
D. Metastatic breast cancer
E. Oligodendroglioma
Answer
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28>A 53-year-old man develops acute, excruciating chest pain that radiates
to his back. En route to the emergency room, he becomes unresponsive,
and is pulseless on arrival. Resuscitation attempts are unsuccessful.
Autopsy reveals massive hemoperitoneum due to a ruptured aortic
dissection. There is a jagged intimal tear in the ascending aorta,
with a dissecting hematoma in the media, extending from the aortic
valve to the renal arteries. Which feature of this scenario most
strongly suggests hypertension as the cause of the aortic dissection?
A. Adventitial tear above renal arteries
B. Dissection through media
C. Involvement of major aortic branches
D. Origin at ascending aorta
E. Rapid exsanguination
Answer
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29>A 68-year-old, well-developed, well-nourished black male presents to
the emergency department complaining of shortness of breath. He denies
chest pain. He has no significant past medical history and takes no
medications. A chest x-ray shows clear lung fields, mild cardiomegaly
and a widened thoracic aorta with linear calcifications. An MRI of the
chest shows aortic dilatation in the thorax, extending proximally,
with atrophy of the muscularis and wrinkling of the intimal surface.
What is the most likely etiology of this condition?
A. Atherosclerosis
B. Hypertension
C. Marfan's syndrome
D. Syphilis infection
E. Takayasu's arteritis
Answer
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30>A 60-year-old man presents to a physician because of difficulty in reading
and coming down stairs, which he attributes to an inability
to "look down." Physical examination reveals that the patient
looks around by moving his head rather than his eyes and als
o shows a distinctive axial rigidity of neck, trunk, and
proximal limb muscles. He shows poverty of movement and
dysarthric speech. Mentally, the patient responds very
slowly but has better memory and intellect than are
initially apparent. Which of the following pathologic
findings of the brain would most likely be present?
A. Depigmentation of the substantia nigra and locus ceruleus
B. Diffuse cortical atrophy with relative sparing of primary motor and sensory areas
C. Selective frontal and temporal lobe atrophy
D. Striking degeneration of the caudate nucleus
E. Widespread neuronal loss and gliosis in subcortical sites
Answer
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31>At which of the following sites is the characteristic triple helical
structure of the collagen initially formed?
A. Extracellular space
B. Golgi body
C. Nucleus
D. Rough endoplasmic reticulum
E. Smooth endoplasmic reticulum
Answer
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32>The nucleus that lies immediately medial (and deep) to the uncus is the
A. amygdala
B. caudate nucleus
C. claustrum
D. hippocampus
E. putamen
F. thalamus
Answer
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33>A 62-year-old female is brought to the emergency room by her husband
with complaints of shortness of breath. Which of the following physical
findings would be the most reliable indicator that she is experiencing
heart failure?
A. A third heart sound (S3)
B. A fourth heart sound (S4)
C. Ascites
D. Orthopnea
E. Pulmonary rales
Answer
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34> A couple brings their son in to a specialty clinic for evaluation of
recurrent bacterial infections involving the respiratory tract. Other
family members have a similar disorder, as noted in the pedigree above.
Which of the following is the most likely diagnosis?
A. Bruton's agammaglobulinemia
B. Common variable immunodeficiency
C. DiGeorge syndrome
D. Hereditary angioedema
E. Isolated IgA deficiency
Answer
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35>Two young boys are playing at a daycare center. One holds a ball on top
of some blocks that the other child has placed on the floor. The second
child helps steady the blocks, then the first child lets go of the ball
, knocking the blocks down to the floor. They both watch and then repeat
the process. These children are most likely
A. 10 months old
B. 16 months old
C. 18 months old
D. 24 months old
E. 48 months old
Answer
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36>In which of the following neurodegenerative conditions would you expect
to observe the phenomenon known as anticipation?
A. Familial Alzheimer disease (FAD)
B. Familial amyotrophic lateral sclerosis (ALS)
C. Huntington disease
D. Pick disease
E. Progressive supranuclear palsy
Answer
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38>Which of the following antihistamines would be the most appropriate
treatment for an airline pilot with hay fever?
A. Chlorpheniramine
B. Diphenhydramine
C. Meclizine
D. Pyrilamine
E. Terfenadine
Answer
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39>A newborn baby has multiple hemorrhages. Clotting studies demonstrate
an elevated prothrombin time. An abnormality of which of the following
biochemical processes is likely present in this patient?
A. Conversion of homocysteine to methionine
B. Conversion of methylmalonyl CoA to succinyl CoA
C. Degradation of cystathionine
D. Formation of gamma-carboxyglutamate residues
E. Hydroxylation of proline
Answer
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40>Examination of an autopsy specimen from a Mexican immigrant demonstrates
a heart with massive dilation of the aortic root and adjacent aortic arch.
Opening the aorta reveals a smooth interior wall without obvious lesions.
If a histological section through the aortic wall is made, which of the
following would most likely be seen?
A. A heavy eosinophilic infiltrate
B. Fibrinoid necrosis with a neutrophilic infiltration
C. Focal fragmentation of elastic elements
D. Obliterative endarteritis of the vasa vasorum
E. Ring-like calcification of the vessel media
Answer
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41>A 16-year-old girl is brought to emergency room by her parents for
severe right foot pain. The patient states that the pain started 1
day prior to presentation. She cannot recall any recent trauma,
and denies any past medical or surgical problem. She is active
and walks at least 1 hour daily in the nearby forest. She goes
to high school and is doing very well. She gets along well with
her parents except that they insist she should eat more, as her
weight has dropped from 130 to 105 pounds over the past year.
Which of the following is the most likely diagnosis?
A. Conversion disorder
B. Depression with somatic manifestation
C. Injured medial ankle tendon
D. Metatarsal stress fracture
E. Tick bite
Answer
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42>A newborn has a heart rate of 130/min, irregular respirations, and
active muscle movements with good tone. He coughs and grimaces in
response to stimulation; he is pink in color, except for his hands
and feet, which are slightly bluish. This neonate's APGAR score is
A. 6
B. 7
C. 8
D. 9
E. 10

43>Which of the following amino acids would most likely be found on the
surface of a protein molecule?
A. Alanine
B. Arginine
C. Isoleucine
D. Leucine
E. Phenylalanine
F. Tryptophan
Answer
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44>A 46-year-old man sustains a spider bite on his upper eyelid, and an
infection develops. The physician is very concerned about spread of
the infection to the dural venous sinuses of the brain via emissary
veins. With which of the following dural venous sinuses does the
superior ophthalmic vein directly communicate?
A. Cavernous sinus
B. Occipital sinus
C. Sigmoid sinus
D. Superior petrosal sinus
E. Straight sinus
Answer
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45>A 10-week-old apparently healthy infant is laid down for a nap. The
mother sits in a rocking chair nearby reading. At one point, she
hears the baby make a single small cry, but she keeps reading because
the baby quiets quickly. Later, she gets up to check on the child,
whom she finds dead.Careful autopsy would be most likely to reveal
which of the following cardiac findings?
A. Endocarditis
B. Failure of development of the endocardial cushion
C. Large interventricular septal defect
D. Mitral valve stenosis
E. Right ventricular hypertrophy
Answer
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46>A 40-year-old HIV-positive man with a CD4 cell count of 25/mm3
complains of progressive memory loss, confusion, and incontinence.
MRI reveals moderate brain atrophy. The patient subsequently dies
of disseminated aspergillosis. Autopsy confirms the presence of
moderate cerebral atrophy. Histologically, there are multifocal
lymphohistiocytic infiltrates with numerous microglial nodules
and scattered multinucleated giant cells. Which of the following
conditions was most likely responsible for this patient's neurologic
symptoms?
A. Aspergillosis
B. CMV encephalitis
C. HIV encephalitis
D. Mycobacterial infection
E. Vacuolar myelopathy
Answer
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47> The pedigree above illustrates the mode of inheritance for which of
the following diseases?
A. Glucose-6-phosphate dehydrogenase deficiency
B. Leber's hereditary optic neuropathy
C. Neurofibromatosis
D. Sickle cell anemia
E. Tay Sachs disease
Answer
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48>A 45-year-old man develops a large meningioma that compresses the brain.
A head CT scan demonstrates a subfalcine herniation. This herniation
would most likely damage which of the following structures?
A. Cerebellar tonsils
B. Cingulate gyrus
C. Medial temporal lobe
D. Medulla
E. Midbrain
Answer
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49>A middle-aged patient develops a gelatinous, well-circumscribed mass
in her right cerebral hemisphere. Biopsy of the mass reveals neoplastic
cells with a "fried egg" morphology. Which of the following tumors does
this patient most likely have?
A. Choroid plexus papilloma
B. Ependymoma
C. Glioblastoma multiforme
D. Oligodendroglioma
E. Pilocytic astrocytoma
Answer
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50>A patient develops an excruciatingly painful infection of the anterior
half of the external ear canal. Which of the following nerves transmits
this impulse?
A. Auricular branch of the vagus
B. Auriculotemporal nerve
C. Greater auricular nerve
D. Lesser occipital nerve
E. Vestibulocochlear nerve
Answer
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Answers
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1>The correct answer is A. An exudate results from leakage of protein-rich fluid from the plasma into the interstitium. It is usually the result of increased vascular permeability caused by inflammation. Exudates also contain numerous acute or chronic inflammatory cells, depending on the inciting event. Of the above choices, only bacterial pleuritis would produce an exudate. If pleuritis is caused by pyogenic organisms, the exudate is purulent (neutrophil-rich). If pleural inflammation is due to mycobacterial infection or neoplastic infiltration, the resulting exudate will contain chronic inflammatory cells.
In contrast, a transudate contains less protein and few inflammatory cells. There are two main mechanisms of transudate formation: 1) decreased oncotic pressure, such as that which occurs in cirrhosis of the liver, nephrotic syndrome, and protein-losing enteropathy (choices B, D, and E); and 2) increased hydrostatic pressure, which may result from congestive heart failure (choice C).
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2>The correct answer is B. Myxopapillary ependymoma is a variant of ependymoma, a tumor arising from ependymal cells. Histologically, myxopapillary ependymoma contains a myxoid (mucus-rich) intercellular matrix, in which spindly neoplastic ependymal cells are arranged in a fascicular and papillary pattern (hence its designation). It is a benign tumor that almost always occurs in the distal segment of the spinal cord, ie, the conus medullaris. Once excised, the patient is cured.
The cerebellum (choice A) is the favorite site for pilocytic astrocytomas, medulloblastomas, and hemangioblastomas, but not ependymomas.
In general, classic ependymomas occur in close proximity to the ventricular cavities, specifically, the 4th ventricle (choice C) in children and the lateral ventricles (choice D) in adults. The myxopapillary variant does not occur in either location.
A midbrain location (choice E) would be truly exceptional for any type of ependymoma.
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3>The correct answer is B. The disease is beta thalassemia major, which is a severe hemolytic anemia characterized by a failure to produce the beta chains of hemoglobin (some HbF, the fetal form of hemoglobin, is produced). The excess alpha chains are insoluble, leading to intra- and extravascular hemolysis. These patients require large numbers of transfusions, and iron overload with resulting secondary hemochromatosis can contribute to eventual cardiac failure. The heart is also damaged by the chronic high output state needed to compensate for the anemia.
Calcium (choice A) deposition is seen in damaged tissues and states with high serum calcium, such as hyperparathyroidism.
Magnesium (choice C), potassium (choice D), and sodium (choice E) are highly soluble and do not usually precipitate in tissues.
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4>The correct answer is A. The test described is the Ames test, which measures damage to DNA and correlates well with carcinogenicity in vitro. It is relatively inexpensive to perform, compared to other tests of carcinogenicity, and is frequently used as a screening test for potential carcinogens.
The nitroblue tetrazolium test (choice B) is used to examine the ability of neutrophils to undergo a respiratory burst, and is used in the diagnosis of hereditary immunodeficiencies.
The Watson-Schwartz test (choice C) detects porphobilinogen in urine, and is used in the The correct answer is C. Any tumor "filling the 4th ventricle" blocks the circulation of cerebrospinal fluid (CSF). This blockage leads to increased intracranial pressure, which manifests with nausea, vomiting, headache, nuchal rigidity, and mental status changes. If surgery is not performed promptly, cerebellar tonsillar herniation and rapid death will ensue. In children, medulloblastoma and ependymoma are the most frequent neoplasms presenting in this manner.
There is no evidence in this case suggesting that acute hemorrhage into the 4th ventricular cavity (choice A) has occurred, nor is medulloblastoma typically associated with this complication. CNS tumors that frequently bleed are metastases from melanoma, renal cell carcinoma, and choriocarcinoma.
Alterations in medullary function (choice B) lead to cardiorespiratory instability and may be caused by direct tumor compression or infiltration of the medulla, neither of which is supported by MRI findings in this case.
Infiltration of the cerebellar vermis (choice D) is certainly seen in many cases of medulloblastoma, a tumor that arises from this midline cerebellar structure. However, this would lead to truncal ataxia and gait instability, not symptoms of increased intracranial pressure.
Medulloblastoma characteristically spreads to the subarachnoid space (choice E), from which the neoplasm may metastasize to distant sites such as spinal cord. Plaques of medulloblastoma are often found on the cerebellar surface, creating a characteristic sugar coating, but this would not cause any significant blockage of CSF circulation.
The correct answer is C. Any tumor "filling the 4th ventricle" blocks the circulation of cerebrospinal fluid (CSF). This blockage leads to increased intracranial pressure, which manifests with nausea, vomiting, headache, nuchal rigidity, and mental status changes. If surgery is not performed promptly, cerebellar tonsillar herniation and rapid death will ensue. In children, medulloblastoma and ependymoma are the most frequent neoplasms presenting in this manner.
There is no evidence in this case suggesting that acute hemorrhage into the 4th ventricular cavity (choice A) has occurred, nor is medulloblastoma typically associated with this complication. CNS tumors that frequently bleed are metastases from melanoma, renal cell carcinoma, and choriocarcinoma.
Alterations in medullary function (choice B) lead to cardiorespiratory instability and may be caused by direct tumor compression or infiltration of the medulla, neither of which is supported by MRI findings in this case.
Infiltration of the cerebellar vermis (choice D) is certainly seen in many cases of medulloblastoma, a tumor that arises from this midline cerebellar structure. However, this would lead to truncal ataxia and gait instability, not symptoms of increased intracranial pressure.
Medulloblastoma characteristically spreads to the subarachnoid space (choice E), from which the neoplasm may metastasize to distant sites such as spinal cord. Plaques of medulloblastoma are often found on the cerebellar surface, creating a characteristic sugar coating, but this would not cause any significant blockage of CSF circulation.
diagnosis of porphyrias.
The Widal test (choice D) is used to diagnose typhoid fever.
The Woellner enzyme test (choice E) detects heterophil antibodies in patients with Epstein-Barr virus infection, such as infectious mononucleosis.
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5>The correct answer is A. A good way to remember what goes through the superior orbital fissure is that everything that innervates the eye, other than the optic nerve, passes through this fissure. This includes the oculomotor nerve (CN III), the trochlear nerve (CN IV), the ophthalmic nerve (V1), and the abducens nerve (CN VI).
The facial nerve (CN VII; choice B) passes through the internal auditory meatus.
The mandibular nerve (V3; choice C) passes through the foramen ovale.
The maxillary nerve (V2; choice D) passes through the foramen rotundum.
The middle meningeal artery (choice E) passes through the foramen spinosum.
The ophthalmic artery (choice F) passes through the optic canal.
The optic nerve (choice G) passes through the optic canal.
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6>The correct answer is B. Cranial nerve IX is the glossopharyngeal nerve, which has a nucleus in the medulla and is necessary for the gag reflex. The gag reflex is elicited by touching either side of the posterior pharynx with a tongue blade, producing bilateral elevation of the palate and bilateral contraction of the pharyngeal muscles. The afferent of this reflex arc consists of the ipsilateral glossopharyngeal nerve, while the vagus nerve, bilaterally, supplies the efferent limb. While the glossopharyngeal nerve may seem to be one of the less important cranial nerves, you should remember to test for its function, as a loss of gag reflex can lead to the patient's death secondary to an aspiration pneumonia. This form of pneumonia can be difficult to treat, as it commonly is due to a mixed flora, which may include a variety of anaerobes.
Cranial nerve VII (choice A) is the facial nerve, which supplies motor function to the face, but does not supply the oropharynx.
Cranial nerve XII (choice C) is the hypoglossal nerve, which supplies the tongue. It is not involved in the gag reflex.
Cranial nerve XI (choice D) is the spinal accessory nerve, which supplies the trapezius and sternocleidomastoid.
Cranial nerve VIII (choice E) is the vestibulocochlear nerve, responsible for hearing and equilibrium.
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7>The correct answer is D. The rule of thumb is that the plasma concentration will reach 50% in one half-life, 75% in two half-lives, 87.5% in three half-lives, etc., so that the difference between the current drug level and 100% halves with each half-life. In this instance, it takes two half-lives to reach 75%. The half-live of this drug is 6 hours, so two half-lives is 12 hours.
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8>The correct answer is E. Herpes simplex can cause a necrotizing, hemorrhagic acute encephalitis that may rapidly produce death. The encephalitis characteristically involves the lower portions of the cerebral cortex, notably the temporal lobes and the base of the frontal lobes, possibly because the infection spreads from the oropharynx.
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9>The correct answer is D. The genetic condition is Marfan syndrome, which is characterized by skeletal, ocular, and cardiovascular abnormalities. Typically, Marfan patients are tall with very long legs and tapering fingers. Laxity of joints is present, so that the thumb can be extended back to the wrist. Chest and spinal column deformities may be present as well. The most frequent cardiovascular anomalies are incompetence of the aortic valve, aortic dissection, and mitral valve prolapse ("floppy valve"). The latter may give rise to mitral regurgitation with the typical auscultatory phenomenon of a systolic click followed by a murmur. The most characteristic ocular change is ectopia lentis, i.e., dislocation of the lens. Most deaths are due to rupture of aortic dissections. The gene mutated in Marfan syndrome encodes fibrillin, a 350-kD protein that serves as scaffolding for the deposition of elastin and formation of elastic fibers. Elastin (choice C) is a 70-kD protein that constitutes the central core of elastic fibers. Abundant elastin is found in the walls of large arteries, uterus, skin, and ligaments. Although elastic fibers are disrupted by mutations of the fibrillin gene, the structure of elastin protein is intact in Marfan syndrome.
Collagen (choice A) is affected in a different set of genetic diseases, including Ehlers-Danlos syndromes and osteogenesis imperfecta.
Dystrophin (choice B) is a large transmembrane protein whose function is essential in maintaining the structural integrity of striated muscle fibers. Mutations of the dystrophin gene, located on X chromosome, are responsible for muscular dystrophy.
Mutations of the gene for myosin b-chain (choice E) account for more than one third of cases of hypertrophic cardiomyopathy, a condition characterized by hypertrophy of the left ventricle. Hypertrophic cardiomyopathy is not associated with mitral valve prolapse.
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10>The correct answer is D. The disease is poliomyelitis, which is caused by the poliovirus, a picorna virus. The virus is spread via the fecal-oral route and can then cause paralysis by infecting the alpha-motor neurons of the anterior horn of the spinal cord. Early symptoms include malaise, headache, fever, nausea, abdominal pain, and sore throat.
Bacterial and fungal infections can be spread by dirt contact with an open wound (choice A).
AIDS is an example of a disease spread by injection (choice B) or exchange of body fluids.
Malaria is an example of a disease spread by mosquitoes (choice C).
Tetanus is the classic example of disease spread by a puncture wound of the foot (choice E).

11>The correct answer is A. This is a typical presentation of an abdominal aortic aneurysm, which is almost always due to severe atherosclerosis. The foci of calcification described occur within the atherosclerotic plaques, and indicate severe atherosclerotic disease.
Congenital weakness of vessels (choice B) can produce berry aneurysms, especially in cerebral vessels in the circle of Willis.
Cystic medial necrosis (choice C) can produce dissecting aneurysms, especially in Marfan's syndrome.
Syphilitic aneurysms (choice D) typically involve the aortic root as it leaves the heart.
Vasculitis (choice E) can produce aneurysms in small arteries.
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12>The correct answer is A. This scenario is classic for "dependent" personality. Look for reliance on others, subordination of own needs, and fear of abandonment. Note that in real life, patients may show symptoms of more than one personality disorder.
Histrionic personality disorder (choice B) is characterized by theatricality, suggestibility, a strong desire for attention, and shallowness.
Obsessive-compulsive personality disorder (choice C), also called anancastic personality disorder, is characterized by obsessions, perfectionism, rigidity, and self-doubt.
Paranoid personality disorder (choice D) is characterized by suspiciousness, oversensitivity, querulousness, and an unforgiving character.
Schizoid personality disorder (choice E) is characterized by emotional coldness, solitude, and social insensitivity.
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13>The correct answer is A. The point of this question is that sometimes the obvious explanation is the correct one. Occlusion of the central retinal artery rapidly causes irreversible blindness with loss of the inner retinal layers. (The photoreceptor rod and cone cells are maintained by the pigment epithelium.) The site of occlusion is typically just posterior to the cribriform plate. A garden-variety atheroma or embolism is overwhelmingly the most common cause of central retinal artery occlusion.
Despite all of the teaching about the risk of blindness in temporal arteritis (choice B), this disorder causes only 10% of central retinal artery occlusions.
Hypertension (choice C) is more apt to cause bleeding than thrombosis.
Polycythemia vera (choice D) could (rarely) cause occlusion because of increased blood viscosity and a tendency for thrombosis.
Tumor (choice E) might also cause retinal artery thrombosis, but this would be far rarer than atheroma.
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14>B
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15>C
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16>The correct answer is A. The facial nerve and the vestibulocochlear nerve emerge from the brain stem at the cerebellopontine angle. These are the two nerves which will be initially affected by a tumor in this region.
The glossopharyngeal nerve and vagus nerve (choices B and E) emerge from the brain stem at the post-olivary sulcus. This is caudal to the cerebellopontine angle.
The optic nerve (choice C) exits from the optic chiasm on the ventral surface of the diencephalon. This is rostral to the cerebellopontine angle.
The trigeminal nerve (choice D) emerges from the brain stem at the anterolateral surface of the pons. This is rostral and ventral to the cerebellopontine angle.
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17>The correct answer is B. This patient has gout, characterized by painful joints due to the precipitation of uric acid crystals caused by excessive production of uric acid (a minority of cases are associated with underexcretion of uric acid). Kidney disease is also seen due to accumulation of uric acid in the tubules. The disease mostly affects males, and is frequently treated with allopurinol, an inhibitor of xanthine oxidase. Xanthine oxidase catalyzes the sequential oxidation of hypoxanthine to xanthine to uric acid.
A defect in urea synthesis (choice A) would result in the accumulation of ammonia.
Phenylketonuria is a disease in which tyrosine cannot be produced from phenylalanine (choice C). It is characterized by a musty body odor and mental retardation.
Defective topoisomerases (choice D) would affect DNA unwinding, and therefore replication.
Leukotrienes (choice E) are potent constrictors of smooth muscle and would more likely lead to bronchoconstriction.
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18>The correct answer is C. Any tumor "filling the 4th ventricle" blocks the circulation of cerebrospinal fluid (CSF). This blockage leads to increased intracranial pressure, which manifests with nausea, vomiting, headache, nuchal rigidity, and mental status changes. If surgery is not performed promptly, cerebellar tonsillar herniation and rapid death will ensue. In children, medulloblastoma and ependymoma are the most frequent neoplasms presenting in this manner.
There is no evidence in this case suggesting that acute hemorrhage into the 4th ventricular cavity (choice A) has occurred, nor is medulloblastoma typically associated with this complication. CNS tumors that frequently bleed are metastases from melanoma, renal cell carcinoma, and choriocarcinoma.
Alterations in medullary function (choice B) lead to cardiorespiratory instability and may be caused by direct tumor compression or infiltration of the medulla, neither of which is supported by MRI findings in this case.
Infiltration of the cerebellar vermis (choice D) is certainly seen in many cases of medulloblastoma, a tumor that arises from this midline cerebellar structure. However, this would lead to truncal ataxia and gait instability, not symptoms of increased intracranial pressure.
Medulloblastoma characteristically spreads to the subarachnoid space (choice E), from which the neoplasm may metastasize to distant sites such as spinal cord. Plaques of medulloblastoma are often found on the cerebellar surface, creating a characteristic sugar coating, but this would not cause any significant blockage of CSF circulation.
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19The correct answer is E. Maternal diabetes is best known for causing large but immature-for-age babies. There is also a specific association between maternal diabetes and transposition of the great vessels. In transposition of the great vessels, the aorta takes off from the anterior part of the right ventricle and the pulmonary trunk takes off from the posterior part of the left ventricle. This produces a complete separation of the systemic and pulmonary circulations. Without surgical correction, most affected infants die within the first months of life, although a patent ductus arteriosus, patent foramen ovale, or ventricular septal defect may allow enough mixing of blood to temporarily sustain life.
In atrial septal defect (choice A) blood can pass from one atrium to the other.
Associate coarctation of the aorta (choice B) with Turner syndrome.
Eisenmenger's syndrome (choice C) is a shift from a left-to-right shunt to a right-to-left shunt secondary to developing pulmonary hypertension.
Tetralogy of Fallot (choice D) consists of a ventricular septal defect, an overriding aorta, pulmonic stenosis, and right ventricular hypertrophy. It is the most common cause of early cyanosis.
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20The correct answer is A. This is an example of displacement. In this defense mechanism, there is a transfer of emotion from a person, object, or situation with which it is appropriately associated to another that causes less distress. Displacement is common and often destructive to other individuals, such as when a man is fired from his job and subsequently beats his wife or children. In the medical setting, the hospital staff is a frequent target of displacement when family members react to their own feelings of guilt about someone's death.
Projection (choice B) occurs when someone attributes his or her own thoughts to a different person.
Reaction formation (choice C) is the unconscious adoption of behavior opposite to one's true feelings.
Regression (choice D) is the adoption of behavior more appropriate to a younger age.
Repression (choice E) is the deeply subconscious blocking of memories or emotions.
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21The correct answer is B. This item tests your knowledge of neurocutaneous syndromes, a group of hereditary conditions characterized by concomitant neoplastic or hamartomatous lesions predominantly affecting the skin and nervous system. Subependymal giant cell astrocytoma is a peculiar astrocytic tumor that grows from the walls of the lateral ventricles. It is pathognomonic of tuberous sclerosis, which is caused by mutations of TS1 or TS2 genes. Tuberous sclerosis manifests with multiple hamartomatous lesions in the skin, CNS, and visceral organs. Cortical tubers are malformed (hamartomatous) nodules of the cortex, probably resulting from faulty cortical development. Other lesions include shagreen patches and ash-leaf spots on the skin, cardiac myomas, and renal angiomyolipomas.
Café-au-lait spots (choice A) are found in both types of neurofibromatosis. Lisch nodules (choice D) are small pigmented nodular lesions of hamartomatous nature that are present in the iris of patients with neurofibromatosis type 1. Schwannomas of the 8th cranial nerve (choice E), especially when bilateral, are typically associated with neurofibromatosis type 2.
Hemangioblastoma (choice C) is a vascular tumor of unknown histologic origin that frequently develops in the cerebellum of patients with von Hippel-Lindau syndrome. Renal cell carcinomas are also common in this disease. Von Hippel-Lindau syndrome is caused by autosomal dominant mutations of the VHL gene, a tumor suppressor gene. You may recall that mutations of VHL gene are also found in the majority of sporadic renal cell carcinomas
--------------------------------------------------------------------------------22The correct answer is A. This is a typical presentation of an abdominal aortic aneurysm, which is almost always due to severe atherosclerosis. The foci of calcification described occur within the atherosclerotic plaques, and indicate severe atherosclerotic disease.
Congenital weakness of vessels (choice B) can produce berry aneurysms.
Cystic medial necrosis (choice C) can produce dissecting aneurysms (e.g., in Marfan's syndrome).
Syphilitic aneurysms (choice D) typically involve the aortic root as it leaves the heart.
Vasculitis (choice E) can produce aneurysms in small arteries.
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23The correct answer is C. The physician should obtain an emergency order of detention, regardless of her threats of a lawsuit. The woman clearly still has suicidal intent, demonstrated by her expressed verbalizations, and is therefore a danger to herself.
Choices A, B, and D clearly place her in a position where she can carry out her plans to terminate her life.
Sedating her (choice E) is the second best choice since it will prevent her from taking her life; however, sedation does not give therapists the opportunity to address the underlying motivations for her suicidal ideation.
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24The correct answer is B. Blocking antibody is generally an IgG antibody against the allergen. It is induced in the allergic patient by administering small amounts of allergen over a period of time. When the person is again exposed to the allergen, the IgG reacts with the allergen before it can reach the IgE-coated mast cell.
Antihistamines (choice A) would block histamine receptors but would not react with the allergen before it could reach the IgE-coated mast cell.
Cromolyn sodium (choice C) is a drug that stabilizes mast cell membranes, thus inhibiting degranulation, but would have no effect on allergen binding to IgE on mast cells.
Epinephrine (choice D) is the mainstay of therapy in severe cases of immediate hypersensitivity (anaphylaxis). It increases intracellular cyclic AMP, thus decreasing mast cell degranulation, and causes smooth muscle dilation in the airways. Epinephrine would have no effect on the binding of the allergen to IgE on mast cells.
Cyclic AMP is degraded in cells by the enzyme phosphodiesterase. Theophylline (choice E) inhibits this enzyme, thereby increasing mast cell cyclic AMP levels and making degranulation less likely without affecting the binding of the allergen to IgE on mast cells.
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25The correct answer is E. At this level, the lateral portion of the dorsal columns (funiculus) is comprised of the fasciculus cuneatus. Axons carrying tactile, proprioceptive, and vibratory information from the ipsilateral arm enter the spinal cord via the dorsal root, ascend the cord in the fasciculus cuneatus, and synapse in the nucleus cuneatus of the caudal medulla. Secondary neurons from this nucleus give rise to internal arcuate fibers, which decussate and ascend to the thalamus (ventral posterolateral nucleus, VPL) as the medial lemniscus. Tertiary neurons from the VPL project to the ipsilateral somatosensory cortex. Therefore, damage to the fasciculus cuneatus would result in a deficit in tactile, proprioceptive, and vibratory sense in the ipsilateral arm, because the fibers that carry this information do not cross until they reach the medulla.
Fine motor control of the fingers (choice A) would be carried principally by the ipsilateral lateral corticospinal tract in the lateral funiculus of the cord.
Motor control of the contralateral foot (choice B) is carried by the ipsilateral corticospinal tract in the lateral funiculus of the cord.
Hemianhidrosis (lack of sweating) over half of the face (choice C) could be produced by interruption of sympathetic innervation to the face. The hypothalamospinal tract projects from the hypothalamus to the intermediolateral cell column at levels T-1 to T-2. It descends in the lateral funiculus of the cord. Interruption of this tract results in Horner's syndrome (miosis, ptosis, hemianhidrosis).
Proprioception from the ipsilateral leg (choice D) is carried by the fasciculus gracilis in the medial part of the dorsal columns.
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26The correct answer is A. While it is hard to develop a deficiency in oil-soluble vitamins (A, D, E, K) because the liver stores these substances, deficiency states can be seen in chronic malnutrition (specifically chronic fat deprivation) and chronic malabsorption. Vitamin A is necessary for formation of retinal pigments (deficiency can cause night blindness) and for appropriate differentiation of epithelial tissues (including hair follicles, mucous membranes, skin, bone, and adrenal cortex).
Vitamin C (choice B), which is water soluble rather than oil soluble, is necessary for collagen synthesis.
Vitamin D (choice C) is important in calcium absorption and metabolism.
Vitamin E (choice D) is a lipid antioxidant that is important in the stabilization of cell membranes.
Vitamin K (choice E) is necessary for normal blood coagulation.
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27The correct answer is C. The most likely diagnosis is an intracranial meningioma. Meningiomas are slow-growing, benign tumors comprising 15% of intracranial tumors; they are most common in the elderly. They originate from either dura mater or arachnoid and are sharply demarcated from brain tissue. Meningiomas often incite an osteoblastic reaction in the overlying cranial bones. Microscopically, the meningioma cells have a tendency to encircle one another, forming whorls and psammoma bodies. Clinically, they present as mass lesions; seizures may occur. The superior parasagittal surface of the frontal lobes is a favorite site of origin. This can often produce leg weakness, since the leg motor fibers that pass down through the internal capsule originate in parasagittal cortical regions. Treatment of meningiomas is usually surgical.
Arachnoid cysts (choice A) are formed by splitting of the arachnoid membrane; most arachnoid cysts arise near the Sylvian fissure. They may present with mass effect, but would be unlikely to produce seizures, prominent focal signs, or reactive hyperostosis.
Glioblastoma multiforme (choice B) is an aggressive malignant astrocytoma that would likely have killed the patient long before 5 years had elapsed.
Metastatic breast cancer (choice D) would generally look different microscopically (the whorling cell pattern is characteristic of meningioma). It would be unlikely for metastatic cancer to cause a reaction in the overlying bone, or to be present long enough to cause symptoms for 5 years.
Oligodendrogliomas (choice E) are glial tumors that could produce the described clinical picture, but usually do not cause hyperostosis of the calvarium or exhibit the characteristic whorling cell pattern microscopically
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28The correct answer is D. The two most common causes of aortic dissection are hypertension and atherosclerosis. An important distinction between the two is that hypertensive dissections generally originate in the ascending aorta, at an intimal surface free of atherosclerosis.
Dissection secondary to atherosclerosis is typically the consequence of a ruptured aortic aneurysm, which originates in the abdominal aorta at the iliac bifurcation. Dissections due to both hypertension and atherosclerosis generally course through the wall within the media (choice B). They both can involve the entire length of the aorta, and may rupture anywhere along its course (choices A and C). Well recognized sequelae of dissections include rupture through the adventitia, compromise of major arterial branches or the aortic valve, cardiac tamponade, and rapid exsanguination (choice E).
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29The correct answer is D. Although rare now because of advances in treatment, syphilitic aortitis and aneurysm are still seen, especially in underserved populations. This complication generally occurs 10 to 40 years after initial infection. The vasa vasorum of the aorta undergoes obliterative endarteritis, leading to atrophy of the muscularis and elastic tissues of the aorta and dilatation. Linear calcifications are often seen in the ascending aorta by x-ray. The intimal wrinkling or "tree barking" is also a common feature. Syphilitic aneurysm can be associated with respiratory distress, cough, congestive heart failure and rarely, rupture.
Atherosclerosis (choice A) is the most common cause of aortic aneurysms. These are most often located in the abdominal aorta, distal to the renal arteries. Intimal wrinkling and linear calcifications are not seen.
Hypertension (choice B) is usually responsible for dissecting aneurysms located within 10 cm of the aortic valve. Patients present with sudden chest pain, which is usually severe and tearing in nature. The chronic hypertension causes a cystic medial necrosis, allowing the separation of vessel layers.
Marfan's syndrome, an autosomal dominant connective tissue disorder (choice C) is also associated with dissecting aneurysms, usually of the ascending aorta. The patients are often very tall with arachnodactyly and ligamentous laxity. Their life-span is generally shortened. This patient's description and age are not consistent with this diagnosis.
Takayasu's arter itis (choice E) is a syndrome characterized by ocular disturbances and weak pulses in the arms. It occurs most frequently in young females. It is considered a giant cell arteritis, and does not cause aneurysms.
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30The correct answer is E. The disease is progressive supranuclear palsy, a degenerative disorder characterized by ophthalmoplegia, pseudobulbar palsy, axial dystonia, and bradykinesia. The presentation described in the question is typical. The pathologic changes consist of widespread neuronal loss and gliosis in subcortical sites with sparing of the cerebral and cerebellar cortices.
Pigmented neurons in the substantia nigra (pars compacta) and locus ceruleus (choice A) selectively degenerate in Parkinson's disease.
In Alzheimer's disease, there is diffuse cortical atrophy (choice B), especially over the association cortex of frontal, temporal, and parietal lobes, with relative sparing of primary sensory and motor areas.
Selective frontal and temporal lobe atrophy (choice C) is characteristic of Pick's disease.
The caudate nucleus and putamen undergo severe atrophy (choice D) in Huntington's disease. Cortical atrophy occurs to a lesser extent.
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31The correct answer is B. Collagen formation begins with transcription of mRNA from appropriate DNA genes in the nucleus. While still within the nucleus, the mRNA is spliced. It is then transported through the cytoplasm to the ribosomes on the rough endoplasmic reticulum. Individual chains are translated on the ribosomes, with the ends feeding into the endoplasmic reticulum lumen. Within the lumen, glycosylation of the individual chains occurs. The material then moves toward the Golgi bodies (whose lumens are connected to the endoplasmic reticulum) where the triple helices of procollagen form. The procollagen is then secreted into the extracellular space, where cleavage of pro-peptides and cross- linking of different triple helices occurs, maturing the collagen.
The extracellular space (choice A) is the site of procollagen cleavage and cross- linking.
The nucleus (choice C) is the site of mRNA transcription and splicing.
The rough endoplasmic reticulum (choice D) is the site of chain translation and glycosylation.
The smooth endoplasmic reticulum (choice E) does not participate in collagen synthesis
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32The correct answer is A. The uncus, which is the medial protrusion of the parahippocampal gyrus, is an external structure seen on the ventral surface of the temporal lobe. The amygdala is a collection of nuclei that lies directly beneath the uncus.
The caudate nucleus (choice B) is a deep nuclear structure that lies lateral to the lateral ventricles.
The claustrum (choice C) is a thin and elongated nucleus that lies just medial to the insular cortex.
The hippocampus (choice D) is a nuclear structure that lies in the interior of the parahippocampal gyrus.
The putamen (choice E) is a nuclear structure that resides lateral to the caudate, and medial to the claustrum.
The thalamus (choice F) is a deep nuclear structure, caudal to the caudate nucleus.
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33The correct answer is A. A third heart sound (S3) is a low-pitched sound occurring at the termination of rapid filling. In patients over 40 years of age, the appearance of a third heart sound strongly suggests congestive heart failure. It also occurs in patients with atrioventricular valve incompetence and can be a normal finding in some young athletes.
A fourth heart sound (S4; choice B) can be a normal finding in some older patients who do not have congestive heart failure.
Ascites (choice C) can also occur in patients with renal, hepatic, or local conditions not associated with cardiac factors.
Both orthopnea (choice D) and pulmonary rales (choice E) often occur secondary to heart failure, however, they both are associated with noncardiac disorders as well.
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34The correct answer is A. Several immunodeficiency disorders have X-linked genetics, including Bruton's agammaglobulinemia, Wiskott-Aldrich syndrome, and some cases of severe combined immunodeficiency diseases. Bruton's agammaglobulinemia is characterized by recurrent respiratory infections caused by pyogenic organisms.
Common variable immunodeficiency (choice B) is a relatively common, but probably heterogeneous, group of acquired and familial diseases. It is distinct from X-linked (Bruton's) agammaglobulinemia.
DiGeorge syndrome (choice C) is due to a developmental malformation of the third and fourth pharyngeal pouches leading to failure of the thymus, and sometimes the parathyroids, to develop. Defective cellular immunity and abnormalities of calcium metabolism are typical.
Hereditary angioedema (choice D) is a usually recessive genetic disease caused by deficiency of C1 esterase inhibitor.
Isolated IgA deficiency (choice E) can be acquired or genetic, but is not usually X-linked.
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35>The correct answer is E. The capacity for cooperative play generally does not begin much befo