06-09-2006, 03:10 PM
SECTION 4
1. DNA from Escherichia coli and Haemophilus influenzae is digested with the restriction endonuclease EcoRI and the fragments separated by agarose gel electrophoresis. An examination of the gel shows that the DNA from H. influenzae was cleaved into numerous smaller fragments while that from E. coli was not. Which of the following best explains this difference?
A. Methylation of E. coli DNA
B. Methylation of H. influenzae DNA
C. Presence of introns in E. coli DNA
D. Presence of introns in H. influenzae DNA
E. Presence of transposons in E. coli DNA
F. Presence of transposons in H. influenzae DNA
2. During the conversion of proinsulin to insulin, bonds between which of the following amino acid residues keep the two chains of the insulin molecule together?
A. Cysteine
B. Lysine
C. Methionine
D. Serine
E. Tyrosine
3. A 27-year-old man with alcoholism is found unresponsive after he drank large amounts of alcohol without eating any food over a 3-day period. His serum glucose concentration is 30 mg/dL. This laboratory finding is most likely due to increased hepatic concentrations of which of the following?
A. Acetyl CoA
B. ATP
C. Lactate
D. NADH
E. Phosphoenolpyruvate
4. Cultured cells are treated with an experimental agent that leads to rapid increases in cytoplasmic calcium concentrations and an increase in cellular diacylglycerol concentrations. This experimental agent most likely stimulates which of the following?
A. Adenylyl cyclase
B. GTPase-activating protein
C. Phospholipase C
D. Protein kinase A
E. Protein kinase C
5. A 54-year-old man comes to the physician because of an intermittent rash and joint pain during the past 9 months. Physical examination shows erythematous, scaly plaques on the extensor surfaces of the upper and lower extremities. Removal of the scales results in small bleeding points in the epidermis. A photograph of the patient's knees is shown. A biopsy specimen of one of the lesions shows neutrophils collecting within the stratum corneum, parakeratosis, and elongated dermal papillae. Which of the following cellular adaptations is most likely in the epidermis of affected skin in this patient?
A. Atrophy
B. Dysplasia
C. Hyperplasia
D. Hypertrophy
E. Metaplasia
F. Neoplasia
6. Southern blotting is used to distinguish maternal and paternal copies of chromosome 7 in a single person. The diagram on the top indicates the DNA region that is amplified and the predicted sites of digestion with restriction endonucleases. The site of hybridization of the labeled probe is also indicated. The gel pattern obtained is shown on the bottom. This pattern is most likely indicative of which of the following?
A. Chromosome walking
B. Meiotic segregation
C. Nondisjunction of chromosomes during meiosis
D. Recombination
E. Restriction fragment length polymorphism
7. A neoplasm in the colon invades through the basement membrane into the lamina propria. Which of the following proteins is most likely to be directly involved in the process of invasion?
A. APC gene product
B. p53 protein
C. ras gene product
D. Rb gene product
E. Type IV collagenase
8. A 33-year-old man of Hispanic descent comes to the emergency department with his 6-year-old daughter. The patient, who speaks only Spanish, appears in mild pain and says "dolor" while pointing to his abdomen. His daughter speaks both English and Spanish. The physician does not speak Spanish. Which of the following initial actions by the physician is most appropriate?
A. Ask a hospital housekeeper who speaks Spanish to interpret for the patient
B. Ask the patient's daughter to serve as an interpreter between the patient and the physician
C. Have a professional interpreter present while the patient is being examined
D. Use a medical English-Spanish dictionary to aid in understanding the patient
E. Use pictures to aid in understanding the patient
9. Which of the following is the rationale for advising a decrease in dietary intake of sodium chloride in patients with hepatic disease who develop edema?
A. Edema fluid has a high concentration of Cl-
B. Glomerular filtration rate is increased
C. Injured hepatocytes are more permeable to Na+
D. Secondary hyperaldosteronism is present
E. Serum globulin concentration is increased
10. A 34-year-old African American man comes to the physician because of muscle aches and reddish brown urine for 12 hours. He began treatment with trimethoprim-sulfamethoxazole 1 day ago for otitis media. He is allergic to penicillin. A sample of blood after centrifugation shows red serum. A deficiency of which of the following enzymes is the most likely cause of these adverse effects?
A. Acetyltransferase
B. Glucose-6-phosphate dehydrogenase
C. γ-Glutamyl transpeptidase
D. Glutathione reductase
E. 1α-Hydroxylase
11. MISSING (sorryL)
12. A 4-year-old boy is brought to the physician because of a 1-day history of restlessness, irritability, and intense perirectal itching. He attends a large day-care facility. Examination of the perirectal region shows small worms that glow under bright light. A photomicrograph of a cellophane tape test is shown. Which of the following is the most appropriate pharmacotherapy?
A. Mebendazole
B. Metronidazole
C. Mitomycin C
D. Pentamidine
E. Tetracycline
13. A 22-year-old woman comes to the physician because of abdominal cramping and bloody diarrhea for 24 hours. She works as a kindergarten teacher, and several of the children at her school have had a gastrointestinal illness in the past week. She takes no medications. Physical examination shows increased bowel sounds. Which of the following is the most likely causal organism?
A. Bacillus anthracis
B. Bacillus subtilis
C. Clostridium difficile
D. Clostridium perfringens
E. Listeria monocytogenes
F. Salmonella typhi
G. Shigella flexneri
14. A 40-year-old man has evidence of chronic heart failure. Clinical signs of both right and left heart failure are present. His heart is dilated. When he was a child, his family settled newly cleared land in the Brazilian Amazon forest, and he lived in a primitive shelter built of mud, wood, and stone for 12 years. Which of the following is the most likely causal organism?
A. Entamoeba histolytica
B. Leishmania braziliensis
C. Schistosoma mansoni
D. Trypanosoma cruzi
E. Wuchereria bancrofti
15. A 24-year-old woman is brought to the emergency department because of a 3-day history of migratory polyarthritis. Over the past 24 hours, she has become unable to walk because of a tenosynovitis of the right patella. Examination of fluid from the right knee joint shows 50,000 leukocytes/mm3. A Gram stain of this fluid and a cervical exudate show gram-negative diplococci. Analysis of her serum for complement activity indicates that a total hemolytic complement activity is only 5% of normal. A deficiency in which of the following complement proteins enhanced the likelihood of this infection in this patient?
A. Activating enzymes (C1r, C1s, C2b, Bb, D)
B. Complement receptors (CR1, CR2, CR3, CR4, C1qR)
C. Membrane attack complex (C5b, C6, C7, C8, C9)
D. Membrane-binding proteins (C4b, C3b)
E. Peptide mediators of inflammation (C5a, C3a, C4a)
16. The table shows survival information for patients who had an operation for a particular form of cancer:
Interval Patients at the Beginning of the Interval Patients Who Died During the Interval Patients Surviving This Interval (%)
0-1 year 500 100 80
1-2 years 400 50 87.5
2-3 years 350 35 90
3-4 years 315 31 90
Based on this information, if a patient survives for 1 year, which of the following is the probability that he or she will survive for 4 years?
A. (0.875 - 0.8) X 0.9 = 0.0675
B. 0.8 X 0.875 X 0.9 X 0.9 = 0.567
C. 0.875 X 0.9 = 0.7875
D. 0.875 X 0.9 X 0.9 = 0.7088
E. 0.9
F. 0.9 X 0.875 = 0.025
17. In a cohort study, 10,000 men who consume alcohol were compared with 10,000 men who do not consume alcohol. The results show that men who consume alcohol have an increased risk for cancer of the bladder that is statistically significant at the 5% level. Which of the following is the most appropriate interpretation of this result?
A. At least 5% of the bladder cancers can be attributed to consumption of alcohol
B. At least 5% of consumers of alcohol will develop cancer of the bladder
C. Such an effect would occur by chance in less than 5% of repeated samples of this size
D. There is at least a 5% increased risk for bladder cancer among consumers of alcohol
E. Men who drink alcohol are 5 times more likely to develop bladder cancer than those who do not drink alcohol
18. A 2-year-old boy with normal size, weight, and development is brought to the physician because of a painful, swollen left knee for the past week. He has had two episodes of asymptomatic hematuria during the past 6 months. Both parents are healthy. He has achieved developmental milestones at appropriate ages. His height and weight are at the 70th percentile. Examination shows bruises and resolving hematomas on both elbows and signs of cutaneous hemorrhages at the site of a deep splinter. Laboratory studies show:
Hemoglobin 12 g/dL
Erythrocyte count normal
Leukocyte count normal
Bleeding time normal
Partial thromboplastin time increased
The most likely diagnosis can be proven by the therapeutic response to a single injection of which of the following materials?
A. Factor I (fibrinogen)
B. Factor VIII (antihemophilic factor)
C. Factor IX (plasma thromboplastin component)
D. Folic acid
E. Vitamin K
19. A 4-year-old girl requires a splenectomy after an automobile collision. Which of the following is most likely to be a long-term complication in this patient?
A. Cytomegalovirus infection
B. Lymphopenia
C. Non-Hodgkin lymphoma
D. Streptococcal infection
E. Thrombocytopenia
20. A 58-year-old man has had progressive weakness over the past 8 months. Examination shows weakness and muscle atrophy in the upper and lower extremities. Muscle stretch reflexes are decreased in the upper extremities and increased in the lower extremities. He has no sensory deficits. Which of the following findings is most likely?
A. Cystic lesion involving midline structures and both ventral horns in the cervical enlargement
B. Demyelination of the left corticospinal tract at all levels of the cord
C. Lesion of the left anterolateral quadrant at C-2
D. Loss of myelin in the dorsal column white matter
E. Loss of myelin in the lateral column white matter and loss of ventral horn motoneurons
21. A newborn has strabismus. Which of the following is the rationale for surgically correcting this problem during early childhood?
A. Cataract formation is more likely in misaligned eyes
B. Neither eye will develop normal monocular vision
C. Normal binocular vision will not develop
D. Retinal ganglion cells in the temporal hemiretinas will degenerate
E. Separate representations of each retina will develop on the visual cortex
22. During an experimental study of the mechanisms of nerve conduction, a researcher isolates a nerve and uses a microelectrode to measure its membrane potential distal to a site of electrical stimulation. The resting potential of the nerve is found to be 蠪90 mV. The following membrane potentials are then recorded at various points in time after stimulation:
Time After Stimulation (msec) Membrane Potential
0 -90 mV
0.5 +25 mV
1 -100 mV
2 -90 mV
The change in membrane potential from the resting potential occurring between 0.5 and 1 milliseconds is most likely caused by increased permeability to which of the following ions?
A. Ca2+
B. Cl-
C. K+
D. Na+
E. PO4-
23. A 37-year-old man is brought to the emergency department after falling down a flight of stairs. Physical examination shows acute alcohol intoxication, a bruise over the left temple, and a swollen, painful wrist. Over the next 30 minutes, his level of consciousness deteriorates, and the left pupil becomes dilated. Which of the following is the most likely cause of the neurologic findings?
A. Cerebral contusion
B. Compression of the facial nerve
C. Laceration of the middle meningeal artery
D. Laceration of the superior cerebral (bridging) veins
E. Laceration of the temporal artery
F. Occult brain tumor unmasked by the fall
24. A 10-year-old girl is brought to the physician because of several 1- to 3-cm, light brown macules on her trunk as shown in the photograph. Physical examination shows axillary freckling. Neurologic examination shows no focal findings. Which of the following is the most likely diagnosis?
A. Dysplastic nevus syndrome
B. Neurofibromatosis
C. Osler-Weber-Rendu disease
D. Tuberous sclerosis
E. von Hippel-Lindau disease
25. A 10-year-old boy is brought to the emergency department by his parents 1 hour after he fell down the steps in the middle of the night. His mother reports that he has a history of wandering around the house at night, but he never seems to recall it afterwards. During these episodes, he does not scream or appear frightened. He is otherwise healthy, and he takes no medications. Physical examination shows a 2-cm area of edema and ecchymosis over the forehead. Polysomnography is most likely to show an abnormality in which of the following stages of sleep?
A. Stage 1
B. Stage 2
C. Slow-wave (delta)
D. REM
26. A 69-year-old man has been taking a dopamine agonist for 4 weeks for Parkinson disease. He has had some benefit from this treatment and decides on his own to increase his dosage. Which of the following adverse effects is most likely to result from this increase in dosage?
A. Depression
B. Exaggerated tremor
C. Generalized hypotonia
D. Psychosis
E. Tardive dyskinesia
27. A 4-year-old child develops a fever, sore throat, ulcerated lesions on the oral mucosa, and a rash on the hands and feet. Which of the following is the most likely viral cause?
A. Adenovirus type 12
B. Coxsackievirus
C. Cytomegalovirus
D. Influenza virus
E. Marburg virus
F. Mumps virus
G. Parvovirus B19
H. Poliovirus type 1
I. Rhinovirus type 8
28. Which of the following labeled structures in the electron micrograph is present in cardiac muscle but not in skeletal muscle?
A. A
B. B
C. C
D. D
29. A 73-year-old man is brought to the emergency department because of excruciating low back pain that began while he was painting his garage 1 day ago. He visits the physician every 6 months for monitoring of hypertension well controlled with a diuretic. An x-ray of the spine shows several osteoblastic lesions in the vertebrae. Which of the following is the most likely diagnosis?
A. Malignant lymphoma
B. Metastatic lung carcinoma
C. Metastatic prostate carcinoma
D. Multiple myeloma
E. Osteosarcoma
30. A 9-year-old girl with cystic fibrosis is brought to the emergency department because of a 12-hour history of fever, severe shortness of breath, and cough productive of thick sputum. Her temperature is 39°C (102.2°F), pulse is 80/min, respirations are 30/min, and blood pressure is 90/60 mm Hg. Diffuse wheezing and scattered rhonchi are heard on auscultation of the chest. The CT scan of the chest shown depicts multiple dilated structures which are a result of multiple infections (as indicated by the arrows). The dilated structures are most likely which of the following?
A. Bronchi
B. Interlobular septae
C. Pulmonary arteries
D. Pulmonary veins
E. Subpleural septae
31. A 25-year-old man comes to the emergency department because of a productive cough, fever, night sweats, shortness of breath, malaise, weight loss, and poor appetite that have progressively worsened over the past 3 weeks. He has worked in construction in the USA since emigrating from Thailand 1 year ago. His temperature is 38.3°C (101°F) and respirations are 30/min. He appears emaciated and has prominent needle tracks on his forearms. Which of the following is the most likely diagnosis?
A. Acute respiratory distress syndrome
B. Atypical viral pneumonia
C. Disseminated tuberculosis
D. Hypersensitivity pneumonitis
E. Metastatic carcinoma of the lung
F. Mycoplasmal pneumonia
32. An 80-year-old woman dies shortly after admission to the hospital because of a 3-day history of progressively increasing shortness of breath. She had a history of heart failure. Examination of the lungs during autopsy shows alveolar damage with distended lymphatics, congested alveolar capillaries, and pink-staining homogenous proteinaceous hyaline material in alveoli. Which of the following is the most likely cause of these findings?
A. Amyloidosis
B. Aspiration pneumonitis
C. Emphysema
D. Pneumonia
E. Pulmonary edema
F. Septic shock
33. An 83-year-old woman comes to the physician for an annual examination. The physician hears a new murmur that is indicative of aortic stenosis. Which of the following diagrams best depicts the murmur?
A. A
B. B
C. C
D. D
E. E
34. A 14-year-old girl is admitted to the hospital because of palpitations, an irregular pulse, migratory polyarthritis, and a low-grade fever. She had acute tonsillitis 3 weeks ago. Assays for antistreptococcal antibodies and C-reactive proteins are positive. Her 10-day stay in the hospital is uneventful, and her ECG changes have resolved. Prophylactic antistreptococcal therapy is used for prevention of which of the following long-term sequelae?
A. Aschoff bodies
B. Fibrinous pericarditis
C. Mitral valve stenosis
D. Polyarthritis
E. Sydenham chorea
35. Coronary blood flow is studied in an animal model of ischemic heart disease. In this model, coronary blood flow is normal when the animal is at rest, but when the animal becomes active coronary vasoconstriction occurs and coronary blood flow decreases. The most likely cause of the observed vasoconstriction is the action of which of the following on vascular smooth muscle?
A. Adenosine
B. Nitric oxide
C. Norepinephrine
D. Oxygen
E. Prostacyclin
36. A 10-year-old girl with a rare form of familial dysautonomia is brought to a university medical center that specializes in treating patients with her condition. She has a debilitating orthostatic hypotension that is most severe in the morning despite treatment with fludrocortisone. After evaluation, a new oral medication is prescribed to increase her blood pressure. This new drug most likely belongs to which of the following classes?
A. Pure beta-adrenergic agonist
B. Pure alpha-adrenergic agonist
C. Pure beta -adrenergic antagonist
D. Pure cholinergic muscarinic agonist
E. Pure cholinergic nicotinic antagonist
37. A 4-year-old boy has had recurrent watery diarrhea, abdominal distention, and increased borborygmi for 3 months. The elimination of most dairy products from his diet causes his symptoms to abate. In which of the following portions of the gastrointestinal tract is an enzyme deficiency most likely?
A. Colon
B. Jejunum
C. Liver
D. Pancreas
E. Stomach
38. A 42-year-old man who is a resident of the USA comes to the physician because of greasy foul-smelling stools and a 5.5-kg (12-lb) weight loss over the past 6 months. He has a 6-year history of chronic abdominal and back pain. The epigastrium is tender on deep palpation. A CT scan of the abdomen shows pancreatic atrophy and calcifications. Which of the following is the most likely cause of his disease?
A. Alcohol dependence
B. Congenital pancreatic cyst
C. Diabetes mellitus
D. Gallstones
E. Heredity
F. Pancreas divisum
G. Protein-calorie malnutrition
39. A 55-year-old man comes to the physician because of a 2-month history of intermittent, severe, sharp abdominal pain that occurs primarily after meals and lasts about 30 to 60 minutes. There is no fever, diarrhea, or weight loss. Physical examination shows no abnormalities. Which of the following is most likely responsible for these symptoms?
A. Acute cholecystitis
B. Ascending cholangitis
C. Biliary colic
D. Primary biliary cirrhosis
E. Sclerosing cholangitis
40. A 22-year-old woman is brought to the emergency department unconscious 30 minutes after sustaining multiple injuries in a motor vehicle collision. Her temperature is 36°C (96.8°F), pulse is 82/min, respirations are 6/min, and blood pressure is 110/75 mm Hg. Physical examination shows significant head trauma with a depressed segment of parietal bone. Arterial blood gas analysis on room air shows:
pH 7.17
PC O2 80 mm Hg
P O2 50 mm Hg
HCO3蠪 28 mEq/L
A. Which of the following renal compensatory responses will occur in this patient?
B. Decreased H+ secretion into the tubule
C. Decreased proximal tubule HCO3- reabsorption
D. Decreased titratable acid excretion
E. Increased HCO3- excretion
F. Increased NH4Cl excretion
41. Two weeks after an upper respiratory illness, a 6-year-old boy develops periorbital and peripheral edema. Other physical findings are normal; blood pressure is 110/60 mm Hg. Laboratory studies show:
Serum
Creatinine 0.8 mg/dL
Protein 4.0 g/dL
Antistreptolysin O titer 80 Todd units (N=12-166)
Urine
Protein 4+
Erythrocytes rare
Which of the following is the most likely diagnosis?
A. Alport syndrome
B. Goodpasture syndrome
C. Membranoproliferative glomerulonephritis
D. Minimal change disease
E. Poststreptococcal glomerulonephritis
42. A 34-year-old man has multicentric capillary hemangioblastomas within the cerebellum, retina, and spinal cord. He is at increased risk for developing which of the following neoplasms in the kidney?
A. Angiomyolipoma
B. Nephroblastoma (Wilms tumor)
C. Oncocytoma
D. Renal cell carcinoma
E. Rhabdomyosarcoma
43. A 32-year-old man with hypertension comes to the physician for a follow-up examination. He has been treated with a β-adrenergic blocking agent for the past 6 weeks. His blood pressure now is 145/90 mm Hg. Physical examination shows no abnormalities. Hydrochlorothiazide is added to the medication regimen. Which of the following best describes the renal mechanism of action of hydrochlorothiazide in this patient?
A. Blocks the mineralocorticoid receptor in the late distal tubule and collecting duct
B. Blocks the Na+-K+-2Cl- symporter
C. Blocks the sodium channel in the late distal tubule and collecting duct
D. Inhibits the Na+-Cl- symporter
E. Produces osmotic diuresis
F. Stimulates carbonic anhydrase in the proximal tubule
44. During an experimental study of male reproductive function, a researcher administers various neutralizing antibodies to male experimental animals in order to map regulatory factors that influence testicular function. A model of positive and negative regulatory pathways is developed and shown in the diagram. If the arrow labeled X represents testosterone, which of the following hormones most likely mediated the effect indicated by the arrow labeled Y?
A. Follicle-stimulating hormone
B. Gonadotropin-releasing hormone
C. Inhibin
D. Luteinizing hormone
E. Testosterone
45. A 32-year-old nulligravid woman comes to the physician because she has not been able to conceive for 2 years. She has a 3-year history of pelvic pain and dyspareunia. Pelvic examination shows enlargement of the left adnexa and nodularity of the cul-de-sac. Laparoscopy shows dark areas 3 to 5 mm in diameter throughout the cul-de-sac. The left adnexa are covered by adhesions and cannot be visualized. A biopsy specimen of the cul-de-sac lesion is most likely to show which of the following?
A. Adenocarcinoma
B. Endometrial glands and stroma
C. Epithelial inclusion cysts
D. Granuloma
E. Mesothelial tumor
46. A 32-year-old man who is a bodybuilder is being evaluated for infertility. He has two children who were born when he was in his early 20s. He has been taking a supplement for the past 3 years to increase muscle mass and strength. He takes no prescribed medications. He appears to be healthy and is muscular. Physical examination shows testicular atrophy. Evaluation shows azoospermia. This patient is most likely taking which of the following substances?
A. Creatine
B. Erythropoietin
C. Growth hormone
D. Prednisone
E. Progesterone
F. Testosterone
47. Which of the following best describes an aspect of the mechanism of action of thyroid hormone?
A. Binding to receptors on mitochondria that directly alter phosphate:oxygen ratio (P/O)
B. Binding to receptors that directly modulate transcription of specific genes
C. Interaction with a G protein associated with the plasma membrane
D. Interaction with guanylyl cyclase without G-protein mediation
E. Interaction with a plasma membrane receptor on target cells
F. Participation by the second messenger cAMP
48. A 63-year-old woman with a 5-year history of type 2 diabetes mellitus comes to the physician for a routine examination. She notes that her blood glucose concentration has been persistently higher over the past 4 months since she gained 9 kg (20 lb) during the holidays. Her diabetes mellitus has been more difficult to control because weight gain causes which of the following to occur?
A. Downregulation of insulin receptors
B. Increased activity of hepatic glucokinase
C. Increased expression of GLUT-4 transporters
D. Inhibition of insulin release
E. Upregulation of insulin signaling
49. A 51-year-old man comes to the physician because of fatigue, weakness, and joint pain for the past 5 days. For the past 9 months, he has been taking 10 mg of prednisone daily for severe rheumatoid arthritis. He tells the physician that he misplaced his medication last week and did not have it replaced. Which of the following mechanisms is most likely responsible for the development of these symptoms in this patient?
A. Adrenal atrophy due to suppression of ACTH secretion
B. Decreased conversion of cortisone to hydrocortisone
C. Downregulation of glucocorticoid receptors in target tissues
D. Increased clearance of endogenous adrenal steroids
E. Increased concentrations of plasma corticosteroid-binding globulin
50. A 75-year-old man is taking medications for hypertension, hypercholesterolemia, insomnia, and osteoarthritis. An age-related decline in which of the following pharmacokinetic processes is most likely to affect his treatment?
A. Gastric absorption
B. Hepatic glucuronidation
C. Hepatic oxidative metabolism
D. Protein binding in the serum
E. Renal tubular secretion
1. DNA from Escherichia coli and Haemophilus influenzae is digested with the restriction endonuclease EcoRI and the fragments separated by agarose gel electrophoresis. An examination of the gel shows that the DNA from H. influenzae was cleaved into numerous smaller fragments while that from E. coli was not. Which of the following best explains this difference?
A. Methylation of E. coli DNA
B. Methylation of H. influenzae DNA
C. Presence of introns in E. coli DNA
D. Presence of introns in H. influenzae DNA
E. Presence of transposons in E. coli DNA
F. Presence of transposons in H. influenzae DNA
2. During the conversion of proinsulin to insulin, bonds between which of the following amino acid residues keep the two chains of the insulin molecule together?
A. Cysteine
B. Lysine
C. Methionine
D. Serine
E. Tyrosine
3. A 27-year-old man with alcoholism is found unresponsive after he drank large amounts of alcohol without eating any food over a 3-day period. His serum glucose concentration is 30 mg/dL. This laboratory finding is most likely due to increased hepatic concentrations of which of the following?
A. Acetyl CoA
B. ATP
C. Lactate
D. NADH
E. Phosphoenolpyruvate
4. Cultured cells are treated with an experimental agent that leads to rapid increases in cytoplasmic calcium concentrations and an increase in cellular diacylglycerol concentrations. This experimental agent most likely stimulates which of the following?
A. Adenylyl cyclase
B. GTPase-activating protein
C. Phospholipase C
D. Protein kinase A
E. Protein kinase C
5. A 54-year-old man comes to the physician because of an intermittent rash and joint pain during the past 9 months. Physical examination shows erythematous, scaly plaques on the extensor surfaces of the upper and lower extremities. Removal of the scales results in small bleeding points in the epidermis. A photograph of the patient's knees is shown. A biopsy specimen of one of the lesions shows neutrophils collecting within the stratum corneum, parakeratosis, and elongated dermal papillae. Which of the following cellular adaptations is most likely in the epidermis of affected skin in this patient?
A. Atrophy
B. Dysplasia
C. Hyperplasia
D. Hypertrophy
E. Metaplasia
F. Neoplasia
6. Southern blotting is used to distinguish maternal and paternal copies of chromosome 7 in a single person. The diagram on the top indicates the DNA region that is amplified and the predicted sites of digestion with restriction endonucleases. The site of hybridization of the labeled probe is also indicated. The gel pattern obtained is shown on the bottom. This pattern is most likely indicative of which of the following?
A. Chromosome walking
B. Meiotic segregation
C. Nondisjunction of chromosomes during meiosis
D. Recombination
E. Restriction fragment length polymorphism
7. A neoplasm in the colon invades through the basement membrane into the lamina propria. Which of the following proteins is most likely to be directly involved in the process of invasion?
A. APC gene product
B. p53 protein
C. ras gene product
D. Rb gene product
E. Type IV collagenase
8. A 33-year-old man of Hispanic descent comes to the emergency department with his 6-year-old daughter. The patient, who speaks only Spanish, appears in mild pain and says "dolor" while pointing to his abdomen. His daughter speaks both English and Spanish. The physician does not speak Spanish. Which of the following initial actions by the physician is most appropriate?
A. Ask a hospital housekeeper who speaks Spanish to interpret for the patient
B. Ask the patient's daughter to serve as an interpreter between the patient and the physician
C. Have a professional interpreter present while the patient is being examined
D. Use a medical English-Spanish dictionary to aid in understanding the patient
E. Use pictures to aid in understanding the patient
9. Which of the following is the rationale for advising a decrease in dietary intake of sodium chloride in patients with hepatic disease who develop edema?
A. Edema fluid has a high concentration of Cl-
B. Glomerular filtration rate is increased
C. Injured hepatocytes are more permeable to Na+
D. Secondary hyperaldosteronism is present
E. Serum globulin concentration is increased
10. A 34-year-old African American man comes to the physician because of muscle aches and reddish brown urine for 12 hours. He began treatment with trimethoprim-sulfamethoxazole 1 day ago for otitis media. He is allergic to penicillin. A sample of blood after centrifugation shows red serum. A deficiency of which of the following enzymes is the most likely cause of these adverse effects?
A. Acetyltransferase
B. Glucose-6-phosphate dehydrogenase
C. γ-Glutamyl transpeptidase
D. Glutathione reductase
E. 1α-Hydroxylase
11. MISSING (sorryL)
12. A 4-year-old boy is brought to the physician because of a 1-day history of restlessness, irritability, and intense perirectal itching. He attends a large day-care facility. Examination of the perirectal region shows small worms that glow under bright light. A photomicrograph of a cellophane tape test is shown. Which of the following is the most appropriate pharmacotherapy?
A. Mebendazole
B. Metronidazole
C. Mitomycin C
D. Pentamidine
E. Tetracycline
13. A 22-year-old woman comes to the physician because of abdominal cramping and bloody diarrhea for 24 hours. She works as a kindergarten teacher, and several of the children at her school have had a gastrointestinal illness in the past week. She takes no medications. Physical examination shows increased bowel sounds. Which of the following is the most likely causal organism?
A. Bacillus anthracis
B. Bacillus subtilis
C. Clostridium difficile
D. Clostridium perfringens
E. Listeria monocytogenes
F. Salmonella typhi
G. Shigella flexneri
14. A 40-year-old man has evidence of chronic heart failure. Clinical signs of both right and left heart failure are present. His heart is dilated. When he was a child, his family settled newly cleared land in the Brazilian Amazon forest, and he lived in a primitive shelter built of mud, wood, and stone for 12 years. Which of the following is the most likely causal organism?
A. Entamoeba histolytica
B. Leishmania braziliensis
C. Schistosoma mansoni
D. Trypanosoma cruzi
E. Wuchereria bancrofti
15. A 24-year-old woman is brought to the emergency department because of a 3-day history of migratory polyarthritis. Over the past 24 hours, she has become unable to walk because of a tenosynovitis of the right patella. Examination of fluid from the right knee joint shows 50,000 leukocytes/mm3. A Gram stain of this fluid and a cervical exudate show gram-negative diplococci. Analysis of her serum for complement activity indicates that a total hemolytic complement activity is only 5% of normal. A deficiency in which of the following complement proteins enhanced the likelihood of this infection in this patient?
A. Activating enzymes (C1r, C1s, C2b, Bb, D)
B. Complement receptors (CR1, CR2, CR3, CR4, C1qR)
C. Membrane attack complex (C5b, C6, C7, C8, C9)
D. Membrane-binding proteins (C4b, C3b)
E. Peptide mediators of inflammation (C5a, C3a, C4a)
16. The table shows survival information for patients who had an operation for a particular form of cancer:
Interval Patients at the Beginning of the Interval Patients Who Died During the Interval Patients Surviving This Interval (%)
0-1 year 500 100 80
1-2 years 400 50 87.5
2-3 years 350 35 90
3-4 years 315 31 90
Based on this information, if a patient survives for 1 year, which of the following is the probability that he or she will survive for 4 years?
A. (0.875 - 0.8) X 0.9 = 0.0675
B. 0.8 X 0.875 X 0.9 X 0.9 = 0.567
C. 0.875 X 0.9 = 0.7875
D. 0.875 X 0.9 X 0.9 = 0.7088
E. 0.9
F. 0.9 X 0.875 = 0.025
17. In a cohort study, 10,000 men who consume alcohol were compared with 10,000 men who do not consume alcohol. The results show that men who consume alcohol have an increased risk for cancer of the bladder that is statistically significant at the 5% level. Which of the following is the most appropriate interpretation of this result?
A. At least 5% of the bladder cancers can be attributed to consumption of alcohol
B. At least 5% of consumers of alcohol will develop cancer of the bladder
C. Such an effect would occur by chance in less than 5% of repeated samples of this size
D. There is at least a 5% increased risk for bladder cancer among consumers of alcohol
E. Men who drink alcohol are 5 times more likely to develop bladder cancer than those who do not drink alcohol
18. A 2-year-old boy with normal size, weight, and development is brought to the physician because of a painful, swollen left knee for the past week. He has had two episodes of asymptomatic hematuria during the past 6 months. Both parents are healthy. He has achieved developmental milestones at appropriate ages. His height and weight are at the 70th percentile. Examination shows bruises and resolving hematomas on both elbows and signs of cutaneous hemorrhages at the site of a deep splinter. Laboratory studies show:
Hemoglobin 12 g/dL
Erythrocyte count normal
Leukocyte count normal
Bleeding time normal
Partial thromboplastin time increased
The most likely diagnosis can be proven by the therapeutic response to a single injection of which of the following materials?
A. Factor I (fibrinogen)
B. Factor VIII (antihemophilic factor)
C. Factor IX (plasma thromboplastin component)
D. Folic acid
E. Vitamin K
19. A 4-year-old girl requires a splenectomy after an automobile collision. Which of the following is most likely to be a long-term complication in this patient?
A. Cytomegalovirus infection
B. Lymphopenia
C. Non-Hodgkin lymphoma
D. Streptococcal infection
E. Thrombocytopenia
20. A 58-year-old man has had progressive weakness over the past 8 months. Examination shows weakness and muscle atrophy in the upper and lower extremities. Muscle stretch reflexes are decreased in the upper extremities and increased in the lower extremities. He has no sensory deficits. Which of the following findings is most likely?
A. Cystic lesion involving midline structures and both ventral horns in the cervical enlargement
B. Demyelination of the left corticospinal tract at all levels of the cord
C. Lesion of the left anterolateral quadrant at C-2
D. Loss of myelin in the dorsal column white matter
E. Loss of myelin in the lateral column white matter and loss of ventral horn motoneurons
21. A newborn has strabismus. Which of the following is the rationale for surgically correcting this problem during early childhood?
A. Cataract formation is more likely in misaligned eyes
B. Neither eye will develop normal monocular vision
C. Normal binocular vision will not develop
D. Retinal ganglion cells in the temporal hemiretinas will degenerate
E. Separate representations of each retina will develop on the visual cortex
22. During an experimental study of the mechanisms of nerve conduction, a researcher isolates a nerve and uses a microelectrode to measure its membrane potential distal to a site of electrical stimulation. The resting potential of the nerve is found to be 蠪90 mV. The following membrane potentials are then recorded at various points in time after stimulation:
Time After Stimulation (msec) Membrane Potential
0 -90 mV
0.5 +25 mV
1 -100 mV
2 -90 mV
The change in membrane potential from the resting potential occurring between 0.5 and 1 milliseconds is most likely caused by increased permeability to which of the following ions?
A. Ca2+
B. Cl-
C. K+
D. Na+
E. PO4-
23. A 37-year-old man is brought to the emergency department after falling down a flight of stairs. Physical examination shows acute alcohol intoxication, a bruise over the left temple, and a swollen, painful wrist. Over the next 30 minutes, his level of consciousness deteriorates, and the left pupil becomes dilated. Which of the following is the most likely cause of the neurologic findings?
A. Cerebral contusion
B. Compression of the facial nerve
C. Laceration of the middle meningeal artery
D. Laceration of the superior cerebral (bridging) veins
E. Laceration of the temporal artery
F. Occult brain tumor unmasked by the fall
24. A 10-year-old girl is brought to the physician because of several 1- to 3-cm, light brown macules on her trunk as shown in the photograph. Physical examination shows axillary freckling. Neurologic examination shows no focal findings. Which of the following is the most likely diagnosis?
A. Dysplastic nevus syndrome
B. Neurofibromatosis
C. Osler-Weber-Rendu disease
D. Tuberous sclerosis
E. von Hippel-Lindau disease
25. A 10-year-old boy is brought to the emergency department by his parents 1 hour after he fell down the steps in the middle of the night. His mother reports that he has a history of wandering around the house at night, but he never seems to recall it afterwards. During these episodes, he does not scream or appear frightened. He is otherwise healthy, and he takes no medications. Physical examination shows a 2-cm area of edema and ecchymosis over the forehead. Polysomnography is most likely to show an abnormality in which of the following stages of sleep?
A. Stage 1
B. Stage 2
C. Slow-wave (delta)
D. REM
26. A 69-year-old man has been taking a dopamine agonist for 4 weeks for Parkinson disease. He has had some benefit from this treatment and decides on his own to increase his dosage. Which of the following adverse effects is most likely to result from this increase in dosage?
A. Depression
B. Exaggerated tremor
C. Generalized hypotonia
D. Psychosis
E. Tardive dyskinesia
27. A 4-year-old child develops a fever, sore throat, ulcerated lesions on the oral mucosa, and a rash on the hands and feet. Which of the following is the most likely viral cause?
A. Adenovirus type 12
B. Coxsackievirus
C. Cytomegalovirus
D. Influenza virus
E. Marburg virus
F. Mumps virus
G. Parvovirus B19
H. Poliovirus type 1
I. Rhinovirus type 8
28. Which of the following labeled structures in the electron micrograph is present in cardiac muscle but not in skeletal muscle?
A. A
B. B
C. C
D. D
29. A 73-year-old man is brought to the emergency department because of excruciating low back pain that began while he was painting his garage 1 day ago. He visits the physician every 6 months for monitoring of hypertension well controlled with a diuretic. An x-ray of the spine shows several osteoblastic lesions in the vertebrae. Which of the following is the most likely diagnosis?
A. Malignant lymphoma
B. Metastatic lung carcinoma
C. Metastatic prostate carcinoma
D. Multiple myeloma
E. Osteosarcoma
30. A 9-year-old girl with cystic fibrosis is brought to the emergency department because of a 12-hour history of fever, severe shortness of breath, and cough productive of thick sputum. Her temperature is 39°C (102.2°F), pulse is 80/min, respirations are 30/min, and blood pressure is 90/60 mm Hg. Diffuse wheezing and scattered rhonchi are heard on auscultation of the chest. The CT scan of the chest shown depicts multiple dilated structures which are a result of multiple infections (as indicated by the arrows). The dilated structures are most likely which of the following?
A. Bronchi
B. Interlobular septae
C. Pulmonary arteries
D. Pulmonary veins
E. Subpleural septae
31. A 25-year-old man comes to the emergency department because of a productive cough, fever, night sweats, shortness of breath, malaise, weight loss, and poor appetite that have progressively worsened over the past 3 weeks. He has worked in construction in the USA since emigrating from Thailand 1 year ago. His temperature is 38.3°C (101°F) and respirations are 30/min. He appears emaciated and has prominent needle tracks on his forearms. Which of the following is the most likely diagnosis?
A. Acute respiratory distress syndrome
B. Atypical viral pneumonia
C. Disseminated tuberculosis
D. Hypersensitivity pneumonitis
E. Metastatic carcinoma of the lung
F. Mycoplasmal pneumonia
32. An 80-year-old woman dies shortly after admission to the hospital because of a 3-day history of progressively increasing shortness of breath. She had a history of heart failure. Examination of the lungs during autopsy shows alveolar damage with distended lymphatics, congested alveolar capillaries, and pink-staining homogenous proteinaceous hyaline material in alveoli. Which of the following is the most likely cause of these findings?
A. Amyloidosis
B. Aspiration pneumonitis
C. Emphysema
D. Pneumonia
E. Pulmonary edema
F. Septic shock
33. An 83-year-old woman comes to the physician for an annual examination. The physician hears a new murmur that is indicative of aortic stenosis. Which of the following diagrams best depicts the murmur?
A. A
B. B
C. C
D. D
E. E
34. A 14-year-old girl is admitted to the hospital because of palpitations, an irregular pulse, migratory polyarthritis, and a low-grade fever. She had acute tonsillitis 3 weeks ago. Assays for antistreptococcal antibodies and C-reactive proteins are positive. Her 10-day stay in the hospital is uneventful, and her ECG changes have resolved. Prophylactic antistreptococcal therapy is used for prevention of which of the following long-term sequelae?
A. Aschoff bodies
B. Fibrinous pericarditis
C. Mitral valve stenosis
D. Polyarthritis
E. Sydenham chorea
35. Coronary blood flow is studied in an animal model of ischemic heart disease. In this model, coronary blood flow is normal when the animal is at rest, but when the animal becomes active coronary vasoconstriction occurs and coronary blood flow decreases. The most likely cause of the observed vasoconstriction is the action of which of the following on vascular smooth muscle?
A. Adenosine
B. Nitric oxide
C. Norepinephrine
D. Oxygen
E. Prostacyclin
36. A 10-year-old girl with a rare form of familial dysautonomia is brought to a university medical center that specializes in treating patients with her condition. She has a debilitating orthostatic hypotension that is most severe in the morning despite treatment with fludrocortisone. After evaluation, a new oral medication is prescribed to increase her blood pressure. This new drug most likely belongs to which of the following classes?
A. Pure beta-adrenergic agonist
B. Pure alpha-adrenergic agonist
C. Pure beta -adrenergic antagonist
D. Pure cholinergic muscarinic agonist
E. Pure cholinergic nicotinic antagonist
37. A 4-year-old boy has had recurrent watery diarrhea, abdominal distention, and increased borborygmi for 3 months. The elimination of most dairy products from his diet causes his symptoms to abate. In which of the following portions of the gastrointestinal tract is an enzyme deficiency most likely?
A. Colon
B. Jejunum
C. Liver
D. Pancreas
E. Stomach
38. A 42-year-old man who is a resident of the USA comes to the physician because of greasy foul-smelling stools and a 5.5-kg (12-lb) weight loss over the past 6 months. He has a 6-year history of chronic abdominal and back pain. The epigastrium is tender on deep palpation. A CT scan of the abdomen shows pancreatic atrophy and calcifications. Which of the following is the most likely cause of his disease?
A. Alcohol dependence
B. Congenital pancreatic cyst
C. Diabetes mellitus
D. Gallstones
E. Heredity
F. Pancreas divisum
G. Protein-calorie malnutrition
39. A 55-year-old man comes to the physician because of a 2-month history of intermittent, severe, sharp abdominal pain that occurs primarily after meals and lasts about 30 to 60 minutes. There is no fever, diarrhea, or weight loss. Physical examination shows no abnormalities. Which of the following is most likely responsible for these symptoms?
A. Acute cholecystitis
B. Ascending cholangitis
C. Biliary colic
D. Primary biliary cirrhosis
E. Sclerosing cholangitis
40. A 22-year-old woman is brought to the emergency department unconscious 30 minutes after sustaining multiple injuries in a motor vehicle collision. Her temperature is 36°C (96.8°F), pulse is 82/min, respirations are 6/min, and blood pressure is 110/75 mm Hg. Physical examination shows significant head trauma with a depressed segment of parietal bone. Arterial blood gas analysis on room air shows:
pH 7.17
PC O2 80 mm Hg
P O2 50 mm Hg
HCO3蠪 28 mEq/L
A. Which of the following renal compensatory responses will occur in this patient?
B. Decreased H+ secretion into the tubule
C. Decreased proximal tubule HCO3- reabsorption
D. Decreased titratable acid excretion
E. Increased HCO3- excretion
F. Increased NH4Cl excretion
41. Two weeks after an upper respiratory illness, a 6-year-old boy develops periorbital and peripheral edema. Other physical findings are normal; blood pressure is 110/60 mm Hg. Laboratory studies show:
Serum
Creatinine 0.8 mg/dL
Protein 4.0 g/dL
Antistreptolysin O titer 80 Todd units (N=12-166)
Urine
Protein 4+
Erythrocytes rare
Which of the following is the most likely diagnosis?
A. Alport syndrome
B. Goodpasture syndrome
C. Membranoproliferative glomerulonephritis
D. Minimal change disease
E. Poststreptococcal glomerulonephritis
42. A 34-year-old man has multicentric capillary hemangioblastomas within the cerebellum, retina, and spinal cord. He is at increased risk for developing which of the following neoplasms in the kidney?
A. Angiomyolipoma
B. Nephroblastoma (Wilms tumor)
C. Oncocytoma
D. Renal cell carcinoma
E. Rhabdomyosarcoma
43. A 32-year-old man with hypertension comes to the physician for a follow-up examination. He has been treated with a β-adrenergic blocking agent for the past 6 weeks. His blood pressure now is 145/90 mm Hg. Physical examination shows no abnormalities. Hydrochlorothiazide is added to the medication regimen. Which of the following best describes the renal mechanism of action of hydrochlorothiazide in this patient?
A. Blocks the mineralocorticoid receptor in the late distal tubule and collecting duct
B. Blocks the Na+-K+-2Cl- symporter
C. Blocks the sodium channel in the late distal tubule and collecting duct
D. Inhibits the Na+-Cl- symporter
E. Produces osmotic diuresis
F. Stimulates carbonic anhydrase in the proximal tubule
44. During an experimental study of male reproductive function, a researcher administers various neutralizing antibodies to male experimental animals in order to map regulatory factors that influence testicular function. A model of positive and negative regulatory pathways is developed and shown in the diagram. If the arrow labeled X represents testosterone, which of the following hormones most likely mediated the effect indicated by the arrow labeled Y?
A. Follicle-stimulating hormone
B. Gonadotropin-releasing hormone
C. Inhibin
D. Luteinizing hormone
E. Testosterone
45. A 32-year-old nulligravid woman comes to the physician because she has not been able to conceive for 2 years. She has a 3-year history of pelvic pain and dyspareunia. Pelvic examination shows enlargement of the left adnexa and nodularity of the cul-de-sac. Laparoscopy shows dark areas 3 to 5 mm in diameter throughout the cul-de-sac. The left adnexa are covered by adhesions and cannot be visualized. A biopsy specimen of the cul-de-sac lesion is most likely to show which of the following?
A. Adenocarcinoma
B. Endometrial glands and stroma
C. Epithelial inclusion cysts
D. Granuloma
E. Mesothelial tumor
46. A 32-year-old man who is a bodybuilder is being evaluated for infertility. He has two children who were born when he was in his early 20s. He has been taking a supplement for the past 3 years to increase muscle mass and strength. He takes no prescribed medications. He appears to be healthy and is muscular. Physical examination shows testicular atrophy. Evaluation shows azoospermia. This patient is most likely taking which of the following substances?
A. Creatine
B. Erythropoietin
C. Growth hormone
D. Prednisone
E. Progesterone
F. Testosterone
47. Which of the following best describes an aspect of the mechanism of action of thyroid hormone?
A. Binding to receptors on mitochondria that directly alter phosphate:oxygen ratio (P/O)
B. Binding to receptors that directly modulate transcription of specific genes
C. Interaction with a G protein associated with the plasma membrane
D. Interaction with guanylyl cyclase without G-protein mediation
E. Interaction with a plasma membrane receptor on target cells
F. Participation by the second messenger cAMP
48. A 63-year-old woman with a 5-year history of type 2 diabetes mellitus comes to the physician for a routine examination. She notes that her blood glucose concentration has been persistently higher over the past 4 months since she gained 9 kg (20 lb) during the holidays. Her diabetes mellitus has been more difficult to control because weight gain causes which of the following to occur?
A. Downregulation of insulin receptors
B. Increased activity of hepatic glucokinase
C. Increased expression of GLUT-4 transporters
D. Inhibition of insulin release
E. Upregulation of insulin signaling
49. A 51-year-old man comes to the physician because of fatigue, weakness, and joint pain for the past 5 days. For the past 9 months, he has been taking 10 mg of prednisone daily for severe rheumatoid arthritis. He tells the physician that he misplaced his medication last week and did not have it replaced. Which of the following mechanisms is most likely responsible for the development of these symptoms in this patient?
A. Adrenal atrophy due to suppression of ACTH secretion
B. Decreased conversion of cortisone to hydrocortisone
C. Downregulation of glucocorticoid receptors in target tissues
D. Increased clearance of endogenous adrenal steroids
E. Increased concentrations of plasma corticosteroid-binding globulin
50. A 75-year-old man is taking medications for hypertension, hypercholesterolemia, insomnia, and osteoarthritis. An age-related decline in which of the following pharmacokinetic processes is most likely to affect his treatment?
A. Gastric absorption
B. Hepatic glucuronidation
C. Hepatic oxidative metabolism
D. Protein binding in the serum
E. Renal tubular secretion