06-09-2006, 03:05 PM
1. Which of the following techniques is most accurate in showing that two bacterial DNAs are identical?
A. Hybridization
B. Northern blotting
C. Nucleotide sequencing
D. Polymerase chain reaction
E. Restriction enzyme analysis
2. Which of the following types of RNA molecules present in a eukaryotic cell is the most abundant?
A. Messenger RNA
B. Mitochondrial messenger RNA
C. Ribosomal RNA
D. Small nuclear RNA
E. Transfer RNA
3. Vitamin B6 (pyridoxine) is required for the enzyme that catalyzes the rate-limiting step in heme synthesis. Which of the following labeled compounds in the diagram is synthesized in this reaction?
A. Glycine and succinyl CoA ---> delta ALA
B. delta ALA ---> porphobililogen
C. porphobililogen ---> uroporphobililogen
D. uroporphobililogen ---> copropophyrinogen
E. copropophyrinogen ---> protophyrin
F. protophyrin ---> Heme
4. Which of the following labeled areas in the electron micrograph of skeletal muscle almost disappears when the muscle is maximally contracted?
A. A
B. B
C. C
D. D
E. E
F. F
5. Which of the following initiates the molecular damage that occurs following transient ischemia and reperfusion of cardiac muscle?
A. Glutathione
B. Hydrogen peroxide
C. Lipid peroxides
D. Phosphatidylinositol
E. Superoxide anion
6. A 35-year-old woman, gravida 2, para 2, comes to the physician for preconceptional counseling. She has an 8-year-old daughter and a 5-year-old son. Both have mild developmental delay. The woman's brother, aged 32 years, has mild mental retardation and fragile X syndrome. Which of the following is the most likely cause of the developmental delay in this woman's children?
A. Chromosomal aneuploidy
B. Expansion of trinucleotide repeat
C. Imprinting
D. Uniparental disomy
E. X chromosome deletion
7. A 62-year-old man has sudden onset of left hemiparesis. A CT scan of the head shows a localized region of cortical infarction. Six months later, which of the following cells are most likely to be observed adjacent to the lesion?
A. Ependymal cells
B. Fibroblasts
C. Glial cells
D. Multinucleate giant cells
E. Myofibroblasts
F. Neutrophils
8. A 45-year-old woman remembers being sexually abused as a child by her older brother. She draws on her childhood experiences to express intense emotions in her work as an actor. This use of her childhood experiences is most illustrative of which of the following coping mechanisms?
A. Denial
B. Displacement
C. Dissociation
D. Isolation
E. Projection
F. Reaction formation
G. Regression
H. Repression
I. Somatization
J. Sublimation
9. A 1-year-old boy is brought to the emergency department because he is having difficulty breathing after drinking water that contains nitrate. He is cyanotic. Blood drawn for laboratory studies is chocolate-colored. His hemoglobin most likely has which of the following properties?
A. Decreased glycosylation
B. Increased binding of 2,3-bisphosphoglycerate
C. Increased proportion of Fe3+
D. Presence of Beta subunits only
E. Sickle cell mutation
10. After intravenous administration of morphine to a population of patients, the incidence of respiratory depression increases as the dosage increases. If naloxone is administered before the morphine, which of the following solid lettered curves represents the effect of naloxone on the percentage of patients with morphine-induced respiratory depression?
A. A
B. B
C. C
D. D
11. A 30-year-old man develops fever, malaise, and a rash on his palms and soles. He frequently hikes in a wooded area near his home and removed an engorged tick from his thigh 1 week ago. Laboratory studies show a leukocyte count of 5500/mm3, a platelet count of 85,000/mm3, and a serum sodium concentration of 128 mEq/L. Which of the following best describes the mechanism of action of the drug of first choice for this condition?
A. Alters capillary permeability
B. Binds to Beta-lactamases
C. Blocks protein synthesis
D. Inhibits transpeptidase
E. Opens ion channels
12. A 26-year-old man comes to the physician's office because he has had shortness of breath and a cough for the past week. He received combination chemotherapy for testicular carcinoma 4 months ago. Auscultation of the lungs discloses fine crackles at the bases. X-ray of the chest shows diffuse pulmonary infiltrates. Which of the following chemotherapeutic drugs is most likely responsible for his symptoms?
A. Bleomycin
B. Cisplatin
C. Cyclophosphamide
D. Daunorubicin
E. Etoposide
F. Ifosfamide
G. Paclitaxel
H. Vinblastine
13. A 40-year-old man comes to the physician because of a 3-month history of midepigastric discomfort that is relieved by eating. His vital signs are normal. Physical examination shows mild epigastric tenderness to palpation. Test of the stool for occult blood is positive. Endoscopy shows a gastric ulcer with heaped-up margins surrounded by edema and inflammation. A biopsy specimen is placed in media containing phenolphthalein. En route to the laboratory, the color of the media changes from yellow to red. Which of the following best explains the change in media pH?
A. Bacterial catalase
B. Bacterial CO2 production
C. Bacterial oxidase
D. Bacterial urease
E. Gastric acid
14. A 32-year-old woman who is seropositive for HIV is admitted to the hospital because of increasing confusion. She dies 2 days later. A tissue section of the meninges obtained at autopsy is shown. Which of the following is the most likely causal organism?
A. Candida albicans
B. Cryptococcus neoformans
C. Mycobacterium avium-intracellulare
D. Pneumocystis jiroveci (formerly P. carinii)
E. Toxoplasma gondii
15. MRL-lpr/lpr mutant mice are useful biomedical research models because of their increased susceptibility to autoimmune disease. These mice are characterized by a defect in the fas gene and a marked increase in T-lymphocyte accumulation as compared with wild-type animals. Based on these characteristics, which of the following is the most likely cause of the increased susceptibility of these mutants to autoimmune disease?
A. Decreased cell-cycle transit time for activated T lymphocytes
B. Decreased dependence on antigen-presenting cells for T-lymphocyte activation
C. Decreased responsiveness to clonal deletion signals in the thymic cortex
D. Increased responsiveness of mature T lymphocytes to antigenic stimulation
E. Increased thymocyte precursor proliferation in the bone marrow
F. Increased thymocyte proliferation rate in the thymic cortex
16. A 40-year-old man with chronic myelogenous leukemia undergoes high-dose chemotherapy and bone marrow transplantation from an unrelated donor. Six weeks after the transplant he has good recovery of hematopoiesis but develops diarrhea, a generalized cutaneous rash, and jaundice. Which of the following cell types most likely underlies these signs?
A. B lymphocytes
B. Eosinophils
C. Mast cells
D. Neutrophils
E. T lymphocytes
17. The P50 is defined as the partial pressure of oxygen (in mm Hg) required to saturate half of the hemoglobin O2 binding sites in a sample of whole blood. In blood from a healthy adult, the P50 is approximately 26 mm Hg when equilibrated with a mixture of 16% O2/5% CO2/79% N2. Which of the following manipulations will cause the P50 of the sample to increase?
A. Cooling the blood from 37°C to 20°C
B. Depleting its erythrocytes of 2,3-bisphosphoglycerate
C. Equilibrating it with 16% O2/12% CO2/72% N2
D. Increasing its pH by 0.3 units using NaOH
E. Mixing it 1:1 with cord blood from a newborn
18. A 10-month-old boy with hemoglobin SS disease is brought to the emergency department by his parents because of severe pain in his feet for 2 hours. He appears acutely ill and is crying. Vital signs are normal except for a pulse of 160/min. Physical examination shows splenomegaly and edematous, tender feet. Laboratory studies show a hemoglobin concentration of 7 g/dL and a reticulocyte count of 12%. A peripheral blood smear shows target cells, poikilocytes, and sickled erythrocytes. Which of the following processes most likely caused the sickled erythrocytes in this patient?
A. Decreased interaction of hemoglobin S with spectrin upon deoxygenation
B. Inability of abnormal beta-chains to form tetramers upon deoxygenation
C. Inability of abnormal beta-chains to form tetramers upon oxygenation
D. Increased interaction of hemoglobin S with spectrin upon oxygenation
E. Spontaneous polymerization of hemoglobin S upon deoxygenation
F. Spontaneous polymerization of hemoglobin S upon oxygenation
19. Which of the following neural crest derivatives is involved in congenital absence of pain perception?
A. Large-diameter neurons of dorsal root ganglia
B. Postganglionic parasympathetic neurons
C. Postganglionic sympathetic neurons
D. Schwann cells
E. Small-diameter neurons of dorsal root ganglia
20. The termination of the pathway that originates in the skin of the right hand and travels through the right cuneate nucleus to the left ventral posterolateral nucleus of the thalamus occurs at which of the following labeled cortical areas of the brain?
A. A
B. B
C. C
D. D
E. E
F. F
G. G
H. H
I. I
J. J
21. A 17-year-old boy is brought to the emergency department after being injured in a football game. He appears to have dislocated his elbow and is unable to abduct and adduct his fingers. Which of the following nerves is most likely injured?
A. Axillary
B. Median
C. Musculocutaneous
D. Radial
E. Ulnar
22. A 5-year-old boy who recently emigrated from West Africa is brought to the physician by his mother for treatment of recurrent follicular conjunctivitis. His father and uncle have had similar symptoms and are now blind. Which of the following is the most likely causal organism?
A. Adenovirus
B. Chlamydia trachomatis
C. Herpes simplex virus
D. Neisseria gonorrhoeae
E. Streptococcus pneumoniae
23. A 48-year-old man with severe uncontrolled systemic hypertension develops a headache and vomiting. Two hours later he has left-sided weakness followed rapidly by loss of consciousness. He dies shortly after admission to the emergency department. A section of his brain as seen at autopsy is shown. The most likely mechanism of the lesion shown is hemorrhage from which of the following?
A. Bridging vein
B. Congenital arteriovenous malformation
C. Intracerebral vein
D. Lenticulostriate artery
E. Saccular aneurysm of the anterior cerebral artery
24. A 32-year-old man comes to the physician because of a 3-year history of knife-like headaches centered on his left eye. They awaken him at night and are associated with left eye lacrimation and rhinorrhea. Over a 2-month period, they occur nightly, last 30 minutes, and resolve. They typically do not occur again for another year. Which of the following is the most likely diagnosis?
A. Cluster headache
B. Intracranial mass
C. Migraine
D. Tension-type headache
25. A 35-year-old woman has a 12-year history of chest pain, backaches, vomiting, abdominal pain, difficulty urinating, fainting spells, and numbness and tingling in her fingers. Which of the following is the most likely diagnosis?
A. Conversion disorder
B. Generalized anxiety disorder
C. Hypochondriasis
D. Major depressive disorder
E. Obsessive-compulsive disorder
F. Somatization disorder
26. An African American male newborn is born at term with pink-white skin, white hair, and translucent irises. His eyes seem sensitive to bright light. Pregnancy and delivery were uncomplicated. Which of the following is the most likely cause of this newborn's condition?
A. Decreased number of melanocytes in the skin
B. Decreased number of melanosomes
C. Failure of neural crest cell differentiation into melanocytes
D. Lack of Golgi complex in melanocytes
E. Lack of tyrosinase activity in melanocytes
27. A 26-year-old woman who is a marathon runner comes to the physician because of a 6-month history of intermittent knee pain that is usually exacerbated by her participation in a race. Physical examination shows no abnormalities. The structure indicated by the arrow on the normal MRI shown is injured. Which of the following structures is most likely injured?
A. Anterior cruciate ligament
B. Lateral meniscus
C. Medial meniscus
D. Popliteal artery
E. Popliteal vein
F. Posterior cruciate ligament
28. A 17-year-old girl has had general malaise and progressive intermittent pain in the knees over the past 6 weeks. She has a history of mouth ulcers. She is using hydrocortisone cream to treat a rash on her cheeks. Laboratory studies show:
Hemoglobin 7.2 g/dL
Hematocrit 31%
Leukocyte count 21,000/ mm3
Platelet count 37,000/ mm3
Which of the following is the most likely diagnosis?
A. Gonococcal arthritis
B. Juvenile rheumatoid arthritis
C. Lyme disease
D. Psoriatic arthritis
E. Reiter syndrome
F. Systemic lupus erythematosus
29. A 47-year-old woman has epigastric burning pain that awakens her from sleep at night. She has been treated with multiple medications for severe rheumatoid arthritis for 2 years. Upper endoscopy shows a gastric ulcer. Which of the following drugs most likely contributed to this adverse effect?
A. Acetaminophen
B. Chloroquine
C. Cyclophosphamide
D. Gold sodium thiomalate
E. Naproxen
F. Penicillamine
30. A 3-month-old infant has a severe lower respiratory tract infection. A virus isolated from the respiratory tract causes the development of multinucleated cells in tissue culture. Which of the following types of drug is most likely to be effective in resolving the infant's infection?
A. Acyclovir
B. Amantadine
C. Corticosteroids
D. Ribavirin
E. Zidovudine (AZT)
31. A 63-year-old man comes to the physician because of "poor sleep" and daytime drowsiness. A sleep laboratory study shows frequent decreases in arterial PO2 and simultaneous increases in arterial PCO2 during sleep. Monitors show chest wall and diaphragmatic motion during these episodes. Which of the following is the most likely diagnosis?
A. Central sleep apnea
B. Chronic obstructive pulmonary disease
C. Kleine-Levin syndrome
D. Obstructive sleep apnea
E. Paroxysmal nocturnal dyspnea
32. In newborns, which of the following mechanisms increases left atrial pressure above right atrial pressure?
A. Closure of the ductus arteriosus
B. Closure of the ductus venosus
C. Decreased pulmonary vascular resistance
D. Decreased resistance to left ventricular output
E. Increased thickness of the right ventricular wall
33. A 30-year-old man develops cold cyanotic fingers while walking his dog on a cold night. Which of the following physiologic mechanisms most likely contributed to this phenomenon?
A. Decreased parasympathetic efferent activity
B. Hypophyseal release of ADH (vasopressin)
C. Increased sympathetic efferent activity
D. Inhibition of the renin-angiotensin system
E. Mast cell release of histamine
F. Platelet release of serotonin
34. A 55-year-old woman who is obese comes to the physician because of daytime drowsiness, early morning headaches, and swollen ankles. During the interview, she says, "My husband tells me I snore too loudly. He can't get any sleep because of it." Echocardiography shows an enlarged right ventricle and poor right ventricular function. Which of the following is most likely responsible for the development of right ventricular failure in this patient?
A. Increased pulmonary artery pressure
B. Increased right ventricular preload
C. Pulmonary embolism
D. Pulmonary valve stenosis
E. Transient hypoxia in right ventricular myocardium
35. Calcium channel blockers are effective antiarrhythmic agents because they inhibit calcium influx into which of the following structures?
A. Atrioventricular node
B. Bundle of His
C. Cardiac muscle of the atria
D. Cardiac muscle of the ventricles
E. Smooth muscle in the coronary arteries
36. A 57-year-old man has had a myocardial infarction. Development of which of the following sequelae of the infarction is associated with decreased survival?
A. Avoidant personality disorder
B. Decreased platelet count
C. Decreased serum catecholamine concentration
D. Major depressive episode
E. Sexual dysfunction
37. A healthy 55-year-old man has had watery diarrhea and lower abdominal cramping discomfort since returning from a trip to Mexico 3 days ago. He has not had a fever or rectal bleeding. Physical examination shows no abnormalities. Stool staining shows no fecal leukocytes. Proctoscopic examination of the rectum shows no abnormalities. Which of the following is the most likely causal organism?
A. Campylobacter jejuni
B. Entamoeba histolytica
C. Escherichia coli
D. Salmonella typhi
E. Shigella sonnei
F. Staphylococcus aureus
G. Yersinia enterocolitica
38. A 62-year-old man comes to the physician because of a 10-day history of mild, diffuse abdominal pain and a rapidly progressive increase in abdominal girth. He has a 10-year history of cirrhosis caused by hepatitis C and alcohol abuse. He stopped all alcohol consumption 8 years ago and has been well until recently. Examination of the abdomen shows massive ascites and a small liver with an irregular texture. A discrete 2-cm nodule is palpated on the liver. Which of the following measurements in this patient's serum is most appropriate to establish a diagnosis?
A. Gamma-Aminobutyric acid (GABA)
B. CA 19-9
C. CA 125
D. Carcinoembryonic antigen
E. Alpha-Fetoprotein
F. Prostate-specific antigen
39. After eating, a 40-year-old woman has a vague feeling of discomfort in the right upper quadrant of the abdomen. Ultrasonography discloses several small calculi, believed to be cholesterol gallstones, in the gallbladder. She begins oral therapy with ursodeoxycholic acid. Which of the following is the best rationale for this treatment?
A. Addition of bilirubin to the bile
B. Decrease in the concentration of bile acids
C. Decrease in the ratio of cholesterol to bile acids
D. Increase in the ability of the gallbladder to concentrate bile
E. Increase in the concentration of lecithin in bile
40. A 54-year-old man has a 3-week history of bilateral ankle swelling. Evaluation shows the following pressures:
Capillary hydrostatic 32 mm Hg N=35-45
Interstitial hydrostatic 10 mm Hg N=2-5
Capillary oncotic 18 mm Hg N=23-27
Interstitial oncotic 0 mm Hg N=1-3
Which of the following is the most likely explanation for the ankle swelling?
A. Chronic bronchitis
B. Congestive heart failure
C. Hepatic venous outflow obstruction
D. Lymphatic obstruction
E. Nephrotic syndrome
41. A 70-year-old man comes to the physician because of discomfort in his lower abdomen for 1 week. Use of over-the-counter ibuprofen has not relieved the symptoms. He has a 25-year history of hypertension currently treated with quinapril. His pulse is 90/min and regular, and blood pressure is 140/80 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no murmurs or gallops. There is a 7-cm mass extending superiorly from the symphysis pubis in the midline. Serum studies show a urea nitrogen (BUN) concentration of 60 mg/dL and a creatinine concentration of 4.5 mg/dL. Ultrasonography of the kidneys shows bilateral hydronephrosis. Which of the following is the most likely cause of this patient's laboratory findings?
A. Angiotensin-converting enzyme (ACE) inhibitor therapy
B. Glomerulonephritis
C. Nonsteroidal anti-inflammatory drug therapy
D. Prerenal azotemia
E. Urethral obstruction
42. A 70-year-old man has a 6-month history of hypertension. Blood pressure is 165/105 mm Hg. Bruits are heard over both carotid arteries and in the right flank. Which of the following renin-angiotensin-aldosterone profiles is most likely in this patient?
Renin Angiotensin Aldosterone
A ↑ ↑ ↑
B ↑ ↑ ↓
C ↑ ↓ ↓
D ↓ ↓ ↓
E ↓ ↓ ↑
F ↓ ↑ ↑
43. A 25-year-old woman is attempting to conceive. A urinary luteinizing hormone kit detects a gonadotropin surge on the first morning void of the 15th day of her menstrual cycle. How soon after this event would it be feasible to detect human chorionic gonadotropin in her serum?
A. That day
B. 2 Days later
C. 4 Days later
D. 8 Days later
E. The 12th day of her next cycle
44. A 30-year-old woman, gravida 1, para 1, comes to the physician for an infertility evaluation. She has had amenorrhea for the past year. Menarche occurred at age 12 years, and pubertal development was normal. Menstrual periods initially occurred at regular intervals, but then became erratic after the delivery of her child 4 years ago. Examination is normal except for atrophy of the vaginal wall. A pregnancy test is negative, and a trial of progesterone does not induce menstruation. Which of the following is the most likely diagnosis?
A. Androgen insensitivity syndrome
B. Gonadal dysgenesis 45,X (Turner syndrome)
C. 21-Hydroxylase deficiency
D. Polycystic ovarian syndrome
E. Premature ovarian failure
F. Pure gonadal dysgenesis (46,XY)
45. A 60-year-old postmenopausal woman comes to the physician because of back pain for 3 months. Her mother and her sister both had breast cancer. Physical examination shows mild tenderness over the lumbar vertebrae. An x-ray of the spine is obtained and shows evidence of a disease process. A photograph representative of a similar condition is shown. To avoid a stimulatory effect on the breast or endometrium, treatment of this condition with which of the following drugs is most appropriate for this patient?
A. Danazol
B. Ethinyl estradiol
C. Mifepristone
D. Raloxifene
E. Tamoxifen
46. A 2-year-old girl is brought to the physician for a routine examination. She is below the 5th percentile for height and weight. Physical examination shows no other abnormalities. Genetic screening shows a new mutation in the ADH (vasopressin)-2 receptor. Water is restricted for 12 hours to test the functional significance of the mutation. At the end of the 12 hours, which of the following sets of laboratory findings is most likely to confirm a loss of function defect in the vasopressin-2 receptor?
Serum ADH(Vasopressin) Serum Osmolality(mOsmol/kg) Urine Osmolality(mOsmol/kg)
A ↓ ↓ 200
B ↓ ↓ 600
C ↓ ↑ 200
D ↓ ↑ 600
E ↑ ↓ 200
F ↑ ↓ 600
G ↑ ↑ 200
H ↑ ↑ 600
47. A 14-year-old boy with type 1 diabetes mellitus is brought to the emergency department comatose. Despite administration of fluids and insulin, his blood pressure decreases, and he goes into cardiac arrest. Laboratory studies at time of admission show the following serum electrolyte results:
Na+ 145 mEq/L
Cl- 101 mEq/L
K+ 3 mEq/L
HCO3- 12 mEq/L
Glucose 350 mg/dL (N=55-100)
Acetone 3 mg/dL (N=0)
Arterial pH 7.2
Which of the following substances in the blood is most likely involved in the cardiac arrest?
A. Acetone
B. Cl-
C. HCO3-
D. K+
E. Na+
48. A 42-year-old woman has fatigue, arthralgias, and vague abdominal pain. She has a history of recurrent kidney stones. Laboratory studies show the following serum values:
Ca2+ ↑
Phosphorus ↑
Parathyroid hormone ↑
Alkaline phosphatase normal
Urine Ca2+ ↓
Which of the following is the most likely site of the underlying pathologic process?
A. Breast
B. Hypothalamus
C. Kidney
D. Ovary
E. Parathyroid
F. Thyroid
49. As a part of a study to determine factors influencing mortality in an intensive care unit, serum creatinine concentrations (in mg/dL) are obtained from 10 consecutive patients at the time of admission to the intensive care unit. The results are shown in the graph. Which of the following statements regarding the sizes of the mean, median, and mode of the serum creatinine values is correct?
A. The mean is larger than the median
B. The median is larger than the mean
C. The median is larger than the mode
D. The mode is larger than the median
E. The mean, median, and mode cannot be determined because the distribution is not normal (gaussian)
50. The clinical chemistry laboratory has obtained a new instrument for serum glucose determinations. The technologist runs sequential tests on the standard supplied by the company. The published glucose value for the standard is 90 mg/dL. The results from the sequential tests are 55 mg/dL, 57 mg/dL, 54 mg/dL, 56 mg/dL, 54 mg/dL, and 55 mg/dL. Based on these data, the most valid conclusion is that the test results are which of the following?
A. Accurate but not precise
B. Precise but not accurate
C. Sensitive but not accurate
D. Sensitive but not specific
E. Sensitive and specific
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A. Hybridization
B. Northern blotting
C. Nucleotide sequencing
D. Polymerase chain reaction
E. Restriction enzyme analysis
2. Which of the following types of RNA molecules present in a eukaryotic cell is the most abundant?
A. Messenger RNA
B. Mitochondrial messenger RNA
C. Ribosomal RNA
D. Small nuclear RNA
E. Transfer RNA
3. Vitamin B6 (pyridoxine) is required for the enzyme that catalyzes the rate-limiting step in heme synthesis. Which of the following labeled compounds in the diagram is synthesized in this reaction?
A. Glycine and succinyl CoA ---> delta ALA
B. delta ALA ---> porphobililogen
C. porphobililogen ---> uroporphobililogen
D. uroporphobililogen ---> copropophyrinogen
E. copropophyrinogen ---> protophyrin
F. protophyrin ---> Heme
4. Which of the following labeled areas in the electron micrograph of skeletal muscle almost disappears when the muscle is maximally contracted?
A. A
B. B
C. C
D. D
E. E
F. F
5. Which of the following initiates the molecular damage that occurs following transient ischemia and reperfusion of cardiac muscle?
A. Glutathione
B. Hydrogen peroxide
C. Lipid peroxides
D. Phosphatidylinositol
E. Superoxide anion
6. A 35-year-old woman, gravida 2, para 2, comes to the physician for preconceptional counseling. She has an 8-year-old daughter and a 5-year-old son. Both have mild developmental delay. The woman's brother, aged 32 years, has mild mental retardation and fragile X syndrome. Which of the following is the most likely cause of the developmental delay in this woman's children?
A. Chromosomal aneuploidy
B. Expansion of trinucleotide repeat
C. Imprinting
D. Uniparental disomy
E. X chromosome deletion
7. A 62-year-old man has sudden onset of left hemiparesis. A CT scan of the head shows a localized region of cortical infarction. Six months later, which of the following cells are most likely to be observed adjacent to the lesion?
A. Ependymal cells
B. Fibroblasts
C. Glial cells
D. Multinucleate giant cells
E. Myofibroblasts
F. Neutrophils
8. A 45-year-old woman remembers being sexually abused as a child by her older brother. She draws on her childhood experiences to express intense emotions in her work as an actor. This use of her childhood experiences is most illustrative of which of the following coping mechanisms?
A. Denial
B. Displacement
C. Dissociation
D. Isolation
E. Projection
F. Reaction formation
G. Regression
H. Repression
I. Somatization
J. Sublimation
9. A 1-year-old boy is brought to the emergency department because he is having difficulty breathing after drinking water that contains nitrate. He is cyanotic. Blood drawn for laboratory studies is chocolate-colored. His hemoglobin most likely has which of the following properties?
A. Decreased glycosylation
B. Increased binding of 2,3-bisphosphoglycerate
C. Increased proportion of Fe3+
D. Presence of Beta subunits only
E. Sickle cell mutation
10. After intravenous administration of morphine to a population of patients, the incidence of respiratory depression increases as the dosage increases. If naloxone is administered before the morphine, which of the following solid lettered curves represents the effect of naloxone on the percentage of patients with morphine-induced respiratory depression?
A. A
B. B
C. C
D. D
11. A 30-year-old man develops fever, malaise, and a rash on his palms and soles. He frequently hikes in a wooded area near his home and removed an engorged tick from his thigh 1 week ago. Laboratory studies show a leukocyte count of 5500/mm3, a platelet count of 85,000/mm3, and a serum sodium concentration of 128 mEq/L. Which of the following best describes the mechanism of action of the drug of first choice for this condition?
A. Alters capillary permeability
B. Binds to Beta-lactamases
C. Blocks protein synthesis
D. Inhibits transpeptidase
E. Opens ion channels
12. A 26-year-old man comes to the physician's office because he has had shortness of breath and a cough for the past week. He received combination chemotherapy for testicular carcinoma 4 months ago. Auscultation of the lungs discloses fine crackles at the bases. X-ray of the chest shows diffuse pulmonary infiltrates. Which of the following chemotherapeutic drugs is most likely responsible for his symptoms?
A. Bleomycin
B. Cisplatin
C. Cyclophosphamide
D. Daunorubicin
E. Etoposide
F. Ifosfamide
G. Paclitaxel
H. Vinblastine
13. A 40-year-old man comes to the physician because of a 3-month history of midepigastric discomfort that is relieved by eating. His vital signs are normal. Physical examination shows mild epigastric tenderness to palpation. Test of the stool for occult blood is positive. Endoscopy shows a gastric ulcer with heaped-up margins surrounded by edema and inflammation. A biopsy specimen is placed in media containing phenolphthalein. En route to the laboratory, the color of the media changes from yellow to red. Which of the following best explains the change in media pH?
A. Bacterial catalase
B. Bacterial CO2 production
C. Bacterial oxidase
D. Bacterial urease
E. Gastric acid
14. A 32-year-old woman who is seropositive for HIV is admitted to the hospital because of increasing confusion. She dies 2 days later. A tissue section of the meninges obtained at autopsy is shown. Which of the following is the most likely causal organism?
A. Candida albicans
B. Cryptococcus neoformans
C. Mycobacterium avium-intracellulare
D. Pneumocystis jiroveci (formerly P. carinii)
E. Toxoplasma gondii
15. MRL-lpr/lpr mutant mice are useful biomedical research models because of their increased susceptibility to autoimmune disease. These mice are characterized by a defect in the fas gene and a marked increase in T-lymphocyte accumulation as compared with wild-type animals. Based on these characteristics, which of the following is the most likely cause of the increased susceptibility of these mutants to autoimmune disease?
A. Decreased cell-cycle transit time for activated T lymphocytes
B. Decreased dependence on antigen-presenting cells for T-lymphocyte activation
C. Decreased responsiveness to clonal deletion signals in the thymic cortex
D. Increased responsiveness of mature T lymphocytes to antigenic stimulation
E. Increased thymocyte precursor proliferation in the bone marrow
F. Increased thymocyte proliferation rate in the thymic cortex
16. A 40-year-old man with chronic myelogenous leukemia undergoes high-dose chemotherapy and bone marrow transplantation from an unrelated donor. Six weeks after the transplant he has good recovery of hematopoiesis but develops diarrhea, a generalized cutaneous rash, and jaundice. Which of the following cell types most likely underlies these signs?
A. B lymphocytes
B. Eosinophils
C. Mast cells
D. Neutrophils
E. T lymphocytes
17. The P50 is defined as the partial pressure of oxygen (in mm Hg) required to saturate half of the hemoglobin O2 binding sites in a sample of whole blood. In blood from a healthy adult, the P50 is approximately 26 mm Hg when equilibrated with a mixture of 16% O2/5% CO2/79% N2. Which of the following manipulations will cause the P50 of the sample to increase?
A. Cooling the blood from 37°C to 20°C
B. Depleting its erythrocytes of 2,3-bisphosphoglycerate
C. Equilibrating it with 16% O2/12% CO2/72% N2
D. Increasing its pH by 0.3 units using NaOH
E. Mixing it 1:1 with cord blood from a newborn
18. A 10-month-old boy with hemoglobin SS disease is brought to the emergency department by his parents because of severe pain in his feet for 2 hours. He appears acutely ill and is crying. Vital signs are normal except for a pulse of 160/min. Physical examination shows splenomegaly and edematous, tender feet. Laboratory studies show a hemoglobin concentration of 7 g/dL and a reticulocyte count of 12%. A peripheral blood smear shows target cells, poikilocytes, and sickled erythrocytes. Which of the following processes most likely caused the sickled erythrocytes in this patient?
A. Decreased interaction of hemoglobin S with spectrin upon deoxygenation
B. Inability of abnormal beta-chains to form tetramers upon deoxygenation
C. Inability of abnormal beta-chains to form tetramers upon oxygenation
D. Increased interaction of hemoglobin S with spectrin upon oxygenation
E. Spontaneous polymerization of hemoglobin S upon deoxygenation
F. Spontaneous polymerization of hemoglobin S upon oxygenation
19. Which of the following neural crest derivatives is involved in congenital absence of pain perception?
A. Large-diameter neurons of dorsal root ganglia
B. Postganglionic parasympathetic neurons
C. Postganglionic sympathetic neurons
D. Schwann cells
E. Small-diameter neurons of dorsal root ganglia
20. The termination of the pathway that originates in the skin of the right hand and travels through the right cuneate nucleus to the left ventral posterolateral nucleus of the thalamus occurs at which of the following labeled cortical areas of the brain?
A. A
B. B
C. C
D. D
E. E
F. F
G. G
H. H
I. I
J. J
21. A 17-year-old boy is brought to the emergency department after being injured in a football game. He appears to have dislocated his elbow and is unable to abduct and adduct his fingers. Which of the following nerves is most likely injured?
A. Axillary
B. Median
C. Musculocutaneous
D. Radial
E. Ulnar
22. A 5-year-old boy who recently emigrated from West Africa is brought to the physician by his mother for treatment of recurrent follicular conjunctivitis. His father and uncle have had similar symptoms and are now blind. Which of the following is the most likely causal organism?
A. Adenovirus
B. Chlamydia trachomatis
C. Herpes simplex virus
D. Neisseria gonorrhoeae
E. Streptococcus pneumoniae
23. A 48-year-old man with severe uncontrolled systemic hypertension develops a headache and vomiting. Two hours later he has left-sided weakness followed rapidly by loss of consciousness. He dies shortly after admission to the emergency department. A section of his brain as seen at autopsy is shown. The most likely mechanism of the lesion shown is hemorrhage from which of the following?
A. Bridging vein
B. Congenital arteriovenous malformation
C. Intracerebral vein
D. Lenticulostriate artery
E. Saccular aneurysm of the anterior cerebral artery
24. A 32-year-old man comes to the physician because of a 3-year history of knife-like headaches centered on his left eye. They awaken him at night and are associated with left eye lacrimation and rhinorrhea. Over a 2-month period, they occur nightly, last 30 minutes, and resolve. They typically do not occur again for another year. Which of the following is the most likely diagnosis?
A. Cluster headache
B. Intracranial mass
C. Migraine
D. Tension-type headache
25. A 35-year-old woman has a 12-year history of chest pain, backaches, vomiting, abdominal pain, difficulty urinating, fainting spells, and numbness and tingling in her fingers. Which of the following is the most likely diagnosis?
A. Conversion disorder
B. Generalized anxiety disorder
C. Hypochondriasis
D. Major depressive disorder
E. Obsessive-compulsive disorder
F. Somatization disorder
26. An African American male newborn is born at term with pink-white skin, white hair, and translucent irises. His eyes seem sensitive to bright light. Pregnancy and delivery were uncomplicated. Which of the following is the most likely cause of this newborn's condition?
A. Decreased number of melanocytes in the skin
B. Decreased number of melanosomes
C. Failure of neural crest cell differentiation into melanocytes
D. Lack of Golgi complex in melanocytes
E. Lack of tyrosinase activity in melanocytes
27. A 26-year-old woman who is a marathon runner comes to the physician because of a 6-month history of intermittent knee pain that is usually exacerbated by her participation in a race. Physical examination shows no abnormalities. The structure indicated by the arrow on the normal MRI shown is injured. Which of the following structures is most likely injured?
A. Anterior cruciate ligament
B. Lateral meniscus
C. Medial meniscus
D. Popliteal artery
E. Popliteal vein
F. Posterior cruciate ligament
28. A 17-year-old girl has had general malaise and progressive intermittent pain in the knees over the past 6 weeks. She has a history of mouth ulcers. She is using hydrocortisone cream to treat a rash on her cheeks. Laboratory studies show:
Hemoglobin 7.2 g/dL
Hematocrit 31%
Leukocyte count 21,000/ mm3
Platelet count 37,000/ mm3
Which of the following is the most likely diagnosis?
A. Gonococcal arthritis
B. Juvenile rheumatoid arthritis
C. Lyme disease
D. Psoriatic arthritis
E. Reiter syndrome
F. Systemic lupus erythematosus
29. A 47-year-old woman has epigastric burning pain that awakens her from sleep at night. She has been treated with multiple medications for severe rheumatoid arthritis for 2 years. Upper endoscopy shows a gastric ulcer. Which of the following drugs most likely contributed to this adverse effect?
A. Acetaminophen
B. Chloroquine
C. Cyclophosphamide
D. Gold sodium thiomalate
E. Naproxen
F. Penicillamine
30. A 3-month-old infant has a severe lower respiratory tract infection. A virus isolated from the respiratory tract causes the development of multinucleated cells in tissue culture. Which of the following types of drug is most likely to be effective in resolving the infant's infection?
A. Acyclovir
B. Amantadine
C. Corticosteroids
D. Ribavirin
E. Zidovudine (AZT)
31. A 63-year-old man comes to the physician because of "poor sleep" and daytime drowsiness. A sleep laboratory study shows frequent decreases in arterial PO2 and simultaneous increases in arterial PCO2 during sleep. Monitors show chest wall and diaphragmatic motion during these episodes. Which of the following is the most likely diagnosis?
A. Central sleep apnea
B. Chronic obstructive pulmonary disease
C. Kleine-Levin syndrome
D. Obstructive sleep apnea
E. Paroxysmal nocturnal dyspnea
32. In newborns, which of the following mechanisms increases left atrial pressure above right atrial pressure?
A. Closure of the ductus arteriosus
B. Closure of the ductus venosus
C. Decreased pulmonary vascular resistance
D. Decreased resistance to left ventricular output
E. Increased thickness of the right ventricular wall
33. A 30-year-old man develops cold cyanotic fingers while walking his dog on a cold night. Which of the following physiologic mechanisms most likely contributed to this phenomenon?
A. Decreased parasympathetic efferent activity
B. Hypophyseal release of ADH (vasopressin)
C. Increased sympathetic efferent activity
D. Inhibition of the renin-angiotensin system
E. Mast cell release of histamine
F. Platelet release of serotonin
34. A 55-year-old woman who is obese comes to the physician because of daytime drowsiness, early morning headaches, and swollen ankles. During the interview, she says, "My husband tells me I snore too loudly. He can't get any sleep because of it." Echocardiography shows an enlarged right ventricle and poor right ventricular function. Which of the following is most likely responsible for the development of right ventricular failure in this patient?
A. Increased pulmonary artery pressure
B. Increased right ventricular preload
C. Pulmonary embolism
D. Pulmonary valve stenosis
E. Transient hypoxia in right ventricular myocardium
35. Calcium channel blockers are effective antiarrhythmic agents because they inhibit calcium influx into which of the following structures?
A. Atrioventricular node
B. Bundle of His
C. Cardiac muscle of the atria
D. Cardiac muscle of the ventricles
E. Smooth muscle in the coronary arteries
36. A 57-year-old man has had a myocardial infarction. Development of which of the following sequelae of the infarction is associated with decreased survival?
A. Avoidant personality disorder
B. Decreased platelet count
C. Decreased serum catecholamine concentration
D. Major depressive episode
E. Sexual dysfunction
37. A healthy 55-year-old man has had watery diarrhea and lower abdominal cramping discomfort since returning from a trip to Mexico 3 days ago. He has not had a fever or rectal bleeding. Physical examination shows no abnormalities. Stool staining shows no fecal leukocytes. Proctoscopic examination of the rectum shows no abnormalities. Which of the following is the most likely causal organism?
A. Campylobacter jejuni
B. Entamoeba histolytica
C. Escherichia coli
D. Salmonella typhi
E. Shigella sonnei
F. Staphylococcus aureus
G. Yersinia enterocolitica
38. A 62-year-old man comes to the physician because of a 10-day history of mild, diffuse abdominal pain and a rapidly progressive increase in abdominal girth. He has a 10-year history of cirrhosis caused by hepatitis C and alcohol abuse. He stopped all alcohol consumption 8 years ago and has been well until recently. Examination of the abdomen shows massive ascites and a small liver with an irregular texture. A discrete 2-cm nodule is palpated on the liver. Which of the following measurements in this patient's serum is most appropriate to establish a diagnosis?
A. Gamma-Aminobutyric acid (GABA)
B. CA 19-9
C. CA 125
D. Carcinoembryonic antigen
E. Alpha-Fetoprotein
F. Prostate-specific antigen
39. After eating, a 40-year-old woman has a vague feeling of discomfort in the right upper quadrant of the abdomen. Ultrasonography discloses several small calculi, believed to be cholesterol gallstones, in the gallbladder. She begins oral therapy with ursodeoxycholic acid. Which of the following is the best rationale for this treatment?
A. Addition of bilirubin to the bile
B. Decrease in the concentration of bile acids
C. Decrease in the ratio of cholesterol to bile acids
D. Increase in the ability of the gallbladder to concentrate bile
E. Increase in the concentration of lecithin in bile
40. A 54-year-old man has a 3-week history of bilateral ankle swelling. Evaluation shows the following pressures:
Capillary hydrostatic 32 mm Hg N=35-45
Interstitial hydrostatic 10 mm Hg N=2-5
Capillary oncotic 18 mm Hg N=23-27
Interstitial oncotic 0 mm Hg N=1-3
Which of the following is the most likely explanation for the ankle swelling?
A. Chronic bronchitis
B. Congestive heart failure
C. Hepatic venous outflow obstruction
D. Lymphatic obstruction
E. Nephrotic syndrome
41. A 70-year-old man comes to the physician because of discomfort in his lower abdomen for 1 week. Use of over-the-counter ibuprofen has not relieved the symptoms. He has a 25-year history of hypertension currently treated with quinapril. His pulse is 90/min and regular, and blood pressure is 140/80 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no murmurs or gallops. There is a 7-cm mass extending superiorly from the symphysis pubis in the midline. Serum studies show a urea nitrogen (BUN) concentration of 60 mg/dL and a creatinine concentration of 4.5 mg/dL. Ultrasonography of the kidneys shows bilateral hydronephrosis. Which of the following is the most likely cause of this patient's laboratory findings?
A. Angiotensin-converting enzyme (ACE) inhibitor therapy
B. Glomerulonephritis
C. Nonsteroidal anti-inflammatory drug therapy
D. Prerenal azotemia
E. Urethral obstruction
42. A 70-year-old man has a 6-month history of hypertension. Blood pressure is 165/105 mm Hg. Bruits are heard over both carotid arteries and in the right flank. Which of the following renin-angiotensin-aldosterone profiles is most likely in this patient?
Renin Angiotensin Aldosterone
A ↑ ↑ ↑
B ↑ ↑ ↓
C ↑ ↓ ↓
D ↓ ↓ ↓
E ↓ ↓ ↑
F ↓ ↑ ↑
43. A 25-year-old woman is attempting to conceive. A urinary luteinizing hormone kit detects a gonadotropin surge on the first morning void of the 15th day of her menstrual cycle. How soon after this event would it be feasible to detect human chorionic gonadotropin in her serum?
A. That day
B. 2 Days later
C. 4 Days later
D. 8 Days later
E. The 12th day of her next cycle
44. A 30-year-old woman, gravida 1, para 1, comes to the physician for an infertility evaluation. She has had amenorrhea for the past year. Menarche occurred at age 12 years, and pubertal development was normal. Menstrual periods initially occurred at regular intervals, but then became erratic after the delivery of her child 4 years ago. Examination is normal except for atrophy of the vaginal wall. A pregnancy test is negative, and a trial of progesterone does not induce menstruation. Which of the following is the most likely diagnosis?
A. Androgen insensitivity syndrome
B. Gonadal dysgenesis 45,X (Turner syndrome)
C. 21-Hydroxylase deficiency
D. Polycystic ovarian syndrome
E. Premature ovarian failure
F. Pure gonadal dysgenesis (46,XY)
45. A 60-year-old postmenopausal woman comes to the physician because of back pain for 3 months. Her mother and her sister both had breast cancer. Physical examination shows mild tenderness over the lumbar vertebrae. An x-ray of the spine is obtained and shows evidence of a disease process. A photograph representative of a similar condition is shown. To avoid a stimulatory effect on the breast or endometrium, treatment of this condition with which of the following drugs is most appropriate for this patient?
A. Danazol
B. Ethinyl estradiol
C. Mifepristone
D. Raloxifene
E. Tamoxifen
46. A 2-year-old girl is brought to the physician for a routine examination. She is below the 5th percentile for height and weight. Physical examination shows no other abnormalities. Genetic screening shows a new mutation in the ADH (vasopressin)-2 receptor. Water is restricted for 12 hours to test the functional significance of the mutation. At the end of the 12 hours, which of the following sets of laboratory findings is most likely to confirm a loss of function defect in the vasopressin-2 receptor?
Serum ADH(Vasopressin) Serum Osmolality(mOsmol/kg) Urine Osmolality(mOsmol/kg)
A ↓ ↓ 200
B ↓ ↓ 600
C ↓ ↑ 200
D ↓ ↑ 600
E ↑ ↓ 200
F ↑ ↓ 600
G ↑ ↑ 200
H ↑ ↑ 600
47. A 14-year-old boy with type 1 diabetes mellitus is brought to the emergency department comatose. Despite administration of fluids and insulin, his blood pressure decreases, and he goes into cardiac arrest. Laboratory studies at time of admission show the following serum electrolyte results:
Na+ 145 mEq/L
Cl- 101 mEq/L
K+ 3 mEq/L
HCO3- 12 mEq/L
Glucose 350 mg/dL (N=55-100)
Acetone 3 mg/dL (N=0)
Arterial pH 7.2
Which of the following substances in the blood is most likely involved in the cardiac arrest?
A. Acetone
B. Cl-
C. HCO3-
D. K+
E. Na+
48. A 42-year-old woman has fatigue, arthralgias, and vague abdominal pain. She has a history of recurrent kidney stones. Laboratory studies show the following serum values:
Ca2+ ↑
Phosphorus ↑
Parathyroid hormone ↑
Alkaline phosphatase normal
Urine Ca2+ ↓
Which of the following is the most likely site of the underlying pathologic process?
A. Breast
B. Hypothalamus
C. Kidney
D. Ovary
E. Parathyroid
F. Thyroid
49. As a part of a study to determine factors influencing mortality in an intensive care unit, serum creatinine concentrations (in mg/dL) are obtained from 10 consecutive patients at the time of admission to the intensive care unit. The results are shown in the graph. Which of the following statements regarding the sizes of the mean, median, and mode of the serum creatinine values is correct?
A. The mean is larger than the median
B. The median is larger than the mean
C. The median is larger than the mode
D. The mode is larger than the median
E. The mean, median, and mode cannot be determined because the distribution is not normal (gaussian)
50. The clinical chemistry laboratory has obtained a new instrument for serum glucose determinations. The technologist runs sequential tests on the standard supplied by the company. The published glucose value for the standard is 90 mg/dL. The results from the sequential tests are 55 mg/dL, 57 mg/dL, 54 mg/dL, 56 mg/dL, 54 mg/dL, and 55 mg/dL. Based on these data, the most valid conclusion is that the test results are which of the following?
A. Accurate but not precise
B. Precise but not accurate
C. Sensitive but not accurate
D. Sensitive but not specific
E. Sensitive and specific
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