06-02-2006, 10:47 PM
hey zido,i would really appreciate it if u would take out some time to ans these blocks....i want to see if my answers were right....thx
SECTION 3
1. Beta-Thalassemia results in the reduction of beta chains of hemoglobin due to errors in the processing of the initial mRNA transcript. The mechanism is most likely to involve a single nucleotide change in which of the following?
A. AUG start codon
B. Enhancer element in the first intron
C. Splice site
D. Termination codon
E. Upstream promoter element
2. The kinetics of an allosteric enzyme is shown in the graph. An experimental drug (Drug X) is added, and the results are shown. Which of the following sets of findings best describes the effect of Drug X on enzyme activity?
K0.5 Vmax
A ↑ ↑
B ↑ No Change
C ↑ ↓
D No Change ↓
E No Change No Change
F No Change ↑
G ↓ ↑
H ↓ No Change
I ↓ ↓
3. Mistargeting of lysosomal enzymes, a problem identified in patients with mucolipidosis II (I-cell disease), involves a defect in which of the following mechanisms involving lysosomal proteins?
A. N-linked glycosylation
B. O-linked glycosylation
C. Phosphorylation of mannose residues
D. Protease responsible for conversion of precursor
E. Sialylation of N-linked oligosaccharides
4. The action potential in excitable cells is a result of changes in which of the following?
A. Energy-driven membrane pumps
B. Ionic equilibrium potential
C. Membrane ionic conductances
D. Transmembrane concentration gradient
5. In a clinical study, 100 subjects are examined for a particular genetic alteration hypothesized to be related to prostate cancer. The results are shown in the table.
Genotype Number of Controls
AA 30
AB 25
BB 45
If A is one allele, and B is the other, which of the following is the frequency of the B allele?
A. 25/200
B. 45/200
C. 50/200
D. 90/200
E. 115/200
6. A 30-year-old woman develops serum sickness (immune complex formation) following parenteral administration of penicillin. A plasma sample from this patient is found to be strongly chemotactic for neutrophils, monocytes, eosinophils, and basophils. Which of the following mediators is most likely responsible for the chemotactic activity in this patient's plasma?
A. C3a
B. C3b
C. C5a
D. C5b
E. C5b-9
7. A 15-year-old girl is brought to the physician for a well-child examination. She is upset because her right breast is larger than the left, and she will not attend physical education classes because she is embarrassed to undress. Breast development began 2 years ago. Menarche has not yet occurred. Examination shows the right breast to be twice as large as the left; the right breast is Tanner stage 4, and the left breast is Tanner stage 3. Which of the following is the most appropriate intervention?
A. Reassurance
B. Psychological evaluation
C. Estrogen therapy
D. Progesterone therapy
E. Operative treatment
8. A 21-year-old man has the sudden onset of fever, sweating, cyanosis, tachycardia, tachypnea, unstable blood pressure, and muscle rigidity after administration of halothane and succinylcholine for an appendectomy. An abnormality in which of the following is the most likely cause of this reaction?
A. Ca2+ releasing channels
B. Carnitine palmitoyltransferase
C. Mitochondrial ATPase
D. Na+-K+ ATPase
E. Phosphorylase beta-kinase
9. The graph shows the plasma concentration of an antibiotic as a function of time after an intravenous bolus. If the antibiotic is administered continuously by intravenous infusion, approximately how many hours will it take for the plasma concentration of the drug to first achieve almost 97% of its steady-state concentration?
A. 3
B. 9
C. 15
D. 21
E. 27
10. A 61-year-old woman has been treated for the past 10 years with warfarin anticoagulant therapy. Her prothrombin time (INR) has remained stable. Which of the following curves shows the most likely change in her prothrombin time following addition of cimetidine to her regimen?
A. A
B. B
C. C
D. D
E. E
11. A 58-year-old man develops esophageal candidiasis 2 days after completing antibiotic therapy for sinusitis. An oral antifungal drug is initiated. Medications include glipizide for type 2 diabetes mellitus and warfarin because of previous cardiac valve replacement. Six days later, his candidiasis has improved, but his serum glucose concentration has decreased from 120 mg/dL to 80 mg/dL, and his prothrombin time has increased from 30 seconds (INR=2.5) to 40 seconds (INR=3.3). Which of the following mechanisms of action explains the antifungal activity of this drug?
A. Decreasing hepatic blood flow
B. Decreasing squalene epoxidase
C. Decreasing synthesis of ergosterol
D. Increasing thymidylate biosynthesis
E. Preventing mitosis by binding tubulin
12. A 65-year-old woman has fever, back pain, and dizziness on standing. Her blood pressure is recorded as 70/0 mm Hg in the emergency department. Blood and urine cultures subsequently grow Escherichia coli. Which of the following bacterial structures is most likely responsible for the hypotension?
A. Capsular polysaccharide
B. Fimbria
C. Lipid A
D. O antigen
E. Porin
13. A 3-year-old boy is evaluated for bilateral conjunctivitis and a dry cough. He attends a day-care center, and most of his classmates have similar symptoms. Physical examination shows intense bilateral conjunctival erythema and a mild serous exudate. The lungs are clear to auscultation. Which of the following viruses is the most likely cause of this child's illness?
A. Adenovirus
B. Mumps virus
C. Parvovirus
D. Respiratory syncytial virus
E. Rhinovirus
F. Rotavirus
14. Cells from a pancreatic carcinoma express very small amounts of class I MHC molecules and are resistant to recognition and killing by CD8+ T lymphocytes isolated from the host individual. Substantial tumor cell lysis is observed when these cells are cultured in the presence of a mixed leukocyte population isolated from the peripheral blood of a normal (cancer-free) individual. Which of the following leukocytes in the blood of the normal individual are most likely responsible for the in vitro lysis of the tumor cells?
A. B-lymphocyte effector (plasma) cells
B. CD4+ T lymphocytes
C. CD8+ T lymphocytes
D. Eosinophils
E. Macrophages
F. Natural killer cells
G. Neutrophils
15. A 4-year-old boy develops uncontrolled bleeding after minor trauma. He has a history of recurrent sinopulmonary infections and eczematous rashes. Which of the following predisposing conditions is most likely present?
A. Bruton agammaglobulinemia
B. Common variable immunodeficiency
C. Selective IgA deficiency
D. Thymic hypoplasia
E. Wiskott-Aldrich syndrome
16. A 3-year study is planned to assess the incidence and etiology of respiratory disease in 574 individuals greater than age 60. The study population consists of two groups: one group cares for children under the age of 5; the second group does not care for children. At the onset of respiratory symptoms, cultures and serologic studies will be performed. Which of the following best describes this study design?
A. Case-control
B. Case series
C. Clinical trial
D. Cohort
E. Community survey
17. The graph shows the oxygen dissociation curve of hemoglobin A for a healthy individual. Which of the following curves best represents the dissociation curve for the same individual after extensive physical training at high altitudes?
A. A
B. B
C. C
D. D
18. A 68-year-old woman has a pathologic fracture of the hip. A photomicrograph of tissue obtained on aspiration of bone marrow is shown. Which of the following is the most likely diagnosis?
A. Acute myelogenous leukemia
B. Chronic lymphocytic leukemia
C. Langerhans cell histiocytosis
D. Metastatic adenocarcinoma
E. Multiple myeloma
19. A 40-year-old woman comes to the physician because of "too much stress in my life now." She describes feeling depressed and tense because of a recent marital separation, a job change, the need to relocate to another city, and the worsening of her 8-year-old son's asthma. Physical examination shows no abnormalities. Laboratory studies are most likely to show which of the following abnormalities?
A. Decreased lymphocyte reactivity to antigens
B. Decreased serum prolactin concentration
C. Increased serum calcium concentration
D. Increased serum thyroid-stimulating hormone concentration
E. Mild normochromic, normocytic anemia
20. A 74-year-old woman has a stroke that results in weakness of the left hand and forearm. Which of the following arteries is most likely occluded?
A. Left anterior cerebral
B. Left middle cerebral
C. Right anterior cerebral
D. Right middle cerebral
21. A 45-year-old woman has weakness in the anterior thigh and is unable to extend her leg at the knee. Flexion of the hip and knee is normal. Sensation is absent on the medial side of the leg. Which of the following nerves is most likely injured?
A. Common peroneal
B. Femoral
C. Lumbosacral trunk
D. Obturator
E. Tibial
22. An unimmunized 2-year-old girl is brought to the emergency department after having a generalized tonic-clonic seizure. She has had a fever and an upper respiratory tract infection for the past 4 days. A Gram stain of cerebrospinal fluid shows numerous gram-negative coccobacilli. Which of the following vaccines would most likely have prevented this infection?
A. DTP
B. Hib
C. Meningococcal
D. Pneumococcal
E. Salmonellal
23. A 6-year-old boy falls off his bicycle and hits his head; he has a transient loss of consciousness. After a brief recovery, he becomes progressively more somnolent. On examination, he has weakness in the right side of the face and right upper extremity. CT scan of the head is shown. The injury at the site labeled X is a consequence of rupture of which of the following arteries?
A. Anterior cerebral
B. Anterior choroidal
C. Anterior communicating
D. Middle cerebral
E. Middle meningeal
24. A 45-year-old man has had generalized jerking movements in his extremities, progressive dementia, and psychotic behavior for the past year. His mother died of a similar illness when she was 50 years old. A CT scan of the head is most likely to show atrophy of which of the following areas of the brain?
A. Caudate nucleus
B. Globus pallidus
C. Hippocampus
D. Putamen
E. Substantia nigra
25. A 22-year-old woman is brought to the emergency department by police after they found her walking naked down the middle of the street. She is screaming that the police are planning to hurt her and that they are members of a secret society that has been following her for months. She is not cooperative with history taking and says quickly, "Plants aren't often watered. Those doorknobs need polishing. Where's the merry-go-round?" She is emaciated, dirty, and disheveled. Laboratory studies show mild microcytic anemia. Urine toxicology screening is negative. Which of the following is the most likely diagnosis?
A. Adjustment disorder with disturbance of conduct
B. Dissociative fugue
C. Schizophreniform disorder
D. Schizotypal personality disorder
E. Substance-induced mood disorder
26. A 3-year-old girl is brought to the emergency department by her parents 10 minutes after they found her playing with an empty medication bottle. The bottle had contained 60 tablets of diazepam. Physical examination and laboratory studies show no abnormalities. This patient is at greatest risk for which of the following complications?
A. Acute tubular necrosis
B. Cardiac arrhythmia
C. Hepatic failure
D. Respiratory depression
E. Seizures
27. A 16-year-old boy is brought to the physician because he is much shorter than his peers. He is proportionally developed and otherwise healthy. An x-ray of the wrist is recommended to assess bone age. Which of the following radiographic findings will be an indication that his growth is complete?
A. Absence of the epiphyseal cartilaginous plate
B. Absence of the primary ossification center
C. Presence of calcified material in the diaphysis
D. Presence of calcified material in the epiphysis
E. Presence of lines of arrested growth
28. A 30-year-old woman who is menstruating develops tenderness of the right knee. She has had arthralgias involving her wrists and knees for the past 3 days. She has no urinary tract symptoms or vaginal discharge. The right knee is swollen and warm to the touch. Approximately 10 necrotic pustules are present on her upper and lower extremities. A Gram stain of scrapings from the cervical os is shown. Which of the following is the most likely causal organism?
A. Calymmatobacterium donovani
B. Chlamydia trachomatis
C. Haemophilus ducreyi
D. Neisseria gonorrhoeae
E. Neisseria meningitidis
29. A 48-year-old man with chronic pancreatic insufficiency develops greasy, foul-smelling stools. He has lost 12 kg (26 lb) over the past 6 months. Which of the following is most likely to be decreased in this man?
A. Chondrocyte formation of type I collagen
B. Mineralization of bone matrix
C. Osteoclast production of carbonic anhydrase II
D. Osteocyte production of alkaline phosphatase
E. Urinary excretion of hydroxyproline
30. A 10-year-old boy is being evaluated because of poor growth, recurrent episodes of sinusitis, and a chronic cough. An x-ray of the chest shows evidence of bronchiectasis. A rare inherited disorder causing immotile, structurally abnormal cilia in the respiratory epithelium is diagnosed. This patient's impaired mucociliary clearance is most likely to predispose him to pulmonary infections with which of the following infectious agents?
A. Candida albicans
B. Cryptococcus neoformans
C. Cytomegalovirus
D. Mycobacterium avium-intracellulare
E. Staphylococcus aureus
31. A previously healthy 30-year-old man comes to the emergency department because of the sudden onset of right shoulder pain and shortness of breath. Breath sounds are absent over the right lung. His cervical trachea at the superior sternal border is shifted to the left. The most likely cause of his condition is rupture of which of the following?
A. Anterior hernia
B. Apical pulmonary bleb
C. Bronchial diverticulum
D. Cystic adenomatoid malformation
E. Posterolateral hernia
32. A 40-year-old man who works in a gravel pit is brought to the emergency department after being hit in the chest by a slab of cement. He does not smoke and does not have a cough. An x-ray of the chest does not show any fractures, but multiple small nodules are seen, some of which are calcified, in the upper lobes. A PPD skin test is negative. Which of the following is the most likely diagnosis?
A. Asbestosis
B. Berylliosis
C. Byssinosis
D. Industrial bronchitis
E. Silicosis
33. A 60-year-old man comes to the physician for a follow-up examination. He had a myocardial infarction of the right ventricle 3 weeks ago. Physical examination shows an accumulation of free fluid in the peritoneal space. Which of the following mechanisms is the most likely cause of this finding?
A. Decreased capillary colloid osmotic pressure
B. Increased capillary hydrostatic pressure
C. Increased capillary permeability
D. Increased lymphatic colloid osmotic pressure
E. Lymphatic obstruction
34. A 65-year-old man comes to the physician because of recurrent lightheadedness. His ECG is shown. Which of the following is most likely responsible for the abnormal ECG pattern in this patient?
A. Atrioventricular conduction disease
B. Atrioventricular re-entrant pathway
C. Ectopic focus in the atria
D. Ectopic focus in the ventricle
E. Sinus node disease
35. An 18-month-old boy is brought to the physician's office for a follow-up cardiac examination. He has a continuous, grade 3/6, rumbling, machinery-like murmur that is heard best at the mid to upper left sternal border. Which of the following is the most likely diagnosis?
A. Mitral valve regurgitation
B. Ostium primum defect
C. Ostium secundum defect
D. Patent ductus arteriosus
E. Sinus of Valsalva fistula
F. Ventricular septal defect
36. A previously healthy 65-year-old man is brought to the emergency department because of severe chest pain for 1 hour. His pulse is 95/min, and blood pressure is 160/110 mm Hg. The lungs are clear to auscultation. An S4 gallop and a grade 2/6 systolic murmur are heard at the apex. An ECG shows 3 mm of ST-segment elevation in leads V2 through V5. The most appropriate treatment includes immediate administration of which of the following?
A. Captopril
B. Digoxin
C. Furosemide
D. Magnesium
E. Tissue plasminogen activator
37. Which of the following hormones, produced by the duodenal and proximal jejunal mucosa, stimulates the release of pancreatic juice rich in digestive enzymes?
A. Cholecystokinin
B. Glucagon
C. Pancreatic polypeptide
D. Secretin
E. Vasoactive intestinal polypeptide
38. An asymptomatic 56-year-old woman has occult blood in her stool. Barium studies of her transverse colon show an intraluminal mass. The surgical specimen is shown. Which of the following is the most likely diagnosis?
A. Adenocarcinoma
B. Carcinoid tumor
C. Polypoid leiomyoma
D. Tubular adenoma
E. Villous adenoma
39. A 94-year-old man has been taking ibuprofen for osteoarthritis for the past 5 years. Two years ago, he developed renal failure, and serum creatinine concentration increased from 1.2 to 2.0 mg/dL. He recently developed gastrointestinal hemorrhage from a gastric ulcer. He wants to continue taking the ibuprofen. Which of the following drugs is most likely to decrease this patient's risk for ibuprofen-induced gastric ulceration?
A. Ampicillin
B. Metronidazole
C. Misoprostol
D. Sucralfate
E. Vitamin B6 (pyridoxine)
40. Which of the following procedures is most likely to increase serum aldosterone concentrations in an experimental subject?
A. Administration of an angiotensin-converting enzyme inhibitor
B. Increase in sodium intake
C. Inhibition of ACTH secretion
D. Intravenous administration of 0.9% saline
E. Restriction of water intake
41. A 65-year-old woman is brought to the emergency department because of lethargy and confusion for 24 hours. She did not fall or injure herself recently. Medications include amitriptyline (150 mg at bedtime) for major depressive disorder and diphenhydramine for the past week (50 mg 3 times daily) for a pruritic rash. Her pulse is 100/min and regular, and blood pressure is 135/80 mm Hg. Physical examination shows a palpable mass in the midline extending 5 cm upward from the pubic symphysis. Her serum urea nitrogen (BUN) concentration is 45 mg/dL, and serum creatinine concentration is 2.8 mg/dL. Which of the following best explains the laboratory results?
A. Acute tubular necrosis
B. Bilateral renal artery stenosis
C. Bilateral ureteral obstruction just distal to the renal pelvis
D. Bilateral ureteral obstruction proximal to the bladder
E. Constrictive pericarditis
F. Decreased ability to empty the bladder
G. Interstitial nephritis
42. A 4-year-old boy is being evaluated for renal calculi. Urinalysis shows numerous hexagonally shaped crystals. Urine concentrations of several amino acids, including ornithine, arginine, and lysine, are increased. Which of the following is the most likely predominant component of the crystals?
A. Calcium oxalate
B. Cholesterol
C. Cystine
D. Struvite
E. Uric acid
43. An otherwise healthy 48-year-old woman comes to the physician because of a change in her menstrual pattern. Her last normal menstrual period was 4 months ago, and she noticed scant staining 3 weeks ago. Her history is otherwise unremarkable. Physical examination shows vaginal dryness. Laboratory evaluation is most likely to show which of the following changes in serum hormone concentrations?
A. Decreased follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
B. Decreased serum prolactin
C. Decreased serum thyroxine (T4)
D. Increased FSH and LH
E. Increased serum prolactin
F. Increased serum T4
44. A 1-year-old child has unilateral cryptorchidism. Even if this problem is surgically corrected, the patient will be at increased risk for development of which of the following in the cryptorchid testis?
A. Germ cell neoplasm
B. Leydig cell tumor
C. Recurrent orchitis
D. Spermatocele
E. Testicular torsion
45. A 33-year-old woman, gravida 2, para 1, at term gives birth to a 4167-g (9 lb 3 oz) male newborn by a spontaneous 30-minute vaginal delivery. Shortly after delivery of the placenta, there is a brisk flow of blood from the uterus. Manual palpation of the uterine cavity shows a large fragment of retained placental material. A curettage shows a fibrous nodule of placental tissue that is firmly adherent to the uterine wall. Which of the following is the most likely cause of the bleeding in this patient?
A. Abruptio placentae
B. Choriocarcinoma
C. Factor XIII (transglutaminase) deficiency
D. Granulomatous endometritis
E. Placenta accreta
F. Placenta previa
46. An 8-year-old boy is brought to the pediatrician's office because of a painful lump on his neck for the past 3 days. Examination shows a 3-cm, tender, rounded, cystic mass in the anterior midline, midway between the chin and sternal notch. The mass elevates with swallowing. Which of the following best explains this finding?
A. Failed differentiation of the third pharyngeal pouch
B. Hypertrophy of the lingual tonsils
C. Incomplete atrophy of the thyroglossal duct
D. Maldevelopment of the first branchial arch
E. Persistence of the second branchial groove
47. A 55-year-old man has had decreasing interest in sex over the past 2 years and impotence for the past 6 months. He has frequent headaches. Examination shows bitemporal visual field defects, sparse facial and pubic hair, and testicular atrophy. MRI shows a 3-cm pituitary tumor. Which of the following sets of serum hormone concentrations is most likely?
Luteinizing Hormone Testosterone
A ↑ ↑
B ↑ ↓
C Normal Normal
D ↓ ↑
E ↓ ↓
48. A 6-month-old male infant is sluggish and appears edematous. He has coarse immature facies and poor muscle tone. Which of the following is the most likely diagnosis?
A. Achondroplasia
B. Congenital hypothyroidism
C. Diastrophic dwarfism
D. Multiple cartilaginous exostoses
E. Muscular dystrophy
F. Myasthenia gravis
G. Osteogenesis imperfecta
H. Tay-Sachs disease
I. Vitamin D-deficiency rickets
49. A 68-year-old man with benign prostatic hypertrophy starts taking terazosin. Which of the following changes is most likely in second messenger levels in the cells affected by this treatment?
A. Decrease in cyclic AMP
B. Decrease in cyclic GMP
C. Decrease in IP3
D. Increase in cyclic AMP
E. Increase in cyclic GMP
F. Increase in IP3
50. After undergoing a minor surgical procedure, a 71-year-old man has difficulty voiding. Which of the following is the most appropriate short-term pharmacotherapy?
A. Atropine
B. Bethanechol
C. Edrophonium
D. Physostigmine
E. Scopolamine
SECTION 3
1. Beta-Thalassemia results in the reduction of beta chains of hemoglobin due to errors in the processing of the initial mRNA transcript. The mechanism is most likely to involve a single nucleotide change in which of the following?
A. AUG start codon
B. Enhancer element in the first intron
C. Splice site
D. Termination codon
E. Upstream promoter element
2. The kinetics of an allosteric enzyme is shown in the graph. An experimental drug (Drug X) is added, and the results are shown. Which of the following sets of findings best describes the effect of Drug X on enzyme activity?
K0.5 Vmax
A ↑ ↑
B ↑ No Change
C ↑ ↓
D No Change ↓
E No Change No Change
F No Change ↑
G ↓ ↑
H ↓ No Change
I ↓ ↓
3. Mistargeting of lysosomal enzymes, a problem identified in patients with mucolipidosis II (I-cell disease), involves a defect in which of the following mechanisms involving lysosomal proteins?
A. N-linked glycosylation
B. O-linked glycosylation
C. Phosphorylation of mannose residues
D. Protease responsible for conversion of precursor
E. Sialylation of N-linked oligosaccharides
4. The action potential in excitable cells is a result of changes in which of the following?
A. Energy-driven membrane pumps
B. Ionic equilibrium potential
C. Membrane ionic conductances
D. Transmembrane concentration gradient
5. In a clinical study, 100 subjects are examined for a particular genetic alteration hypothesized to be related to prostate cancer. The results are shown in the table.
Genotype Number of Controls
AA 30
AB 25
BB 45
If A is one allele, and B is the other, which of the following is the frequency of the B allele?
A. 25/200
B. 45/200
C. 50/200
D. 90/200
E. 115/200
6. A 30-year-old woman develops serum sickness (immune complex formation) following parenteral administration of penicillin. A plasma sample from this patient is found to be strongly chemotactic for neutrophils, monocytes, eosinophils, and basophils. Which of the following mediators is most likely responsible for the chemotactic activity in this patient's plasma?
A. C3a
B. C3b
C. C5a
D. C5b
E. C5b-9
7. A 15-year-old girl is brought to the physician for a well-child examination. She is upset because her right breast is larger than the left, and she will not attend physical education classes because she is embarrassed to undress. Breast development began 2 years ago. Menarche has not yet occurred. Examination shows the right breast to be twice as large as the left; the right breast is Tanner stage 4, and the left breast is Tanner stage 3. Which of the following is the most appropriate intervention?
A. Reassurance
B. Psychological evaluation
C. Estrogen therapy
D. Progesterone therapy
E. Operative treatment
8. A 21-year-old man has the sudden onset of fever, sweating, cyanosis, tachycardia, tachypnea, unstable blood pressure, and muscle rigidity after administration of halothane and succinylcholine for an appendectomy. An abnormality in which of the following is the most likely cause of this reaction?
A. Ca2+ releasing channels
B. Carnitine palmitoyltransferase
C. Mitochondrial ATPase
D. Na+-K+ ATPase
E. Phosphorylase beta-kinase
9. The graph shows the plasma concentration of an antibiotic as a function of time after an intravenous bolus. If the antibiotic is administered continuously by intravenous infusion, approximately how many hours will it take for the plasma concentration of the drug to first achieve almost 97% of its steady-state concentration?
A. 3
B. 9
C. 15
D. 21
E. 27
10. A 61-year-old woman has been treated for the past 10 years with warfarin anticoagulant therapy. Her prothrombin time (INR) has remained stable. Which of the following curves shows the most likely change in her prothrombin time following addition of cimetidine to her regimen?
A. A
B. B
C. C
D. D
E. E
11. A 58-year-old man develops esophageal candidiasis 2 days after completing antibiotic therapy for sinusitis. An oral antifungal drug is initiated. Medications include glipizide for type 2 diabetes mellitus and warfarin because of previous cardiac valve replacement. Six days later, his candidiasis has improved, but his serum glucose concentration has decreased from 120 mg/dL to 80 mg/dL, and his prothrombin time has increased from 30 seconds (INR=2.5) to 40 seconds (INR=3.3). Which of the following mechanisms of action explains the antifungal activity of this drug?
A. Decreasing hepatic blood flow
B. Decreasing squalene epoxidase
C. Decreasing synthesis of ergosterol
D. Increasing thymidylate biosynthesis
E. Preventing mitosis by binding tubulin
12. A 65-year-old woman has fever, back pain, and dizziness on standing. Her blood pressure is recorded as 70/0 mm Hg in the emergency department. Blood and urine cultures subsequently grow Escherichia coli. Which of the following bacterial structures is most likely responsible for the hypotension?
A. Capsular polysaccharide
B. Fimbria
C. Lipid A
D. O antigen
E. Porin
13. A 3-year-old boy is evaluated for bilateral conjunctivitis and a dry cough. He attends a day-care center, and most of his classmates have similar symptoms. Physical examination shows intense bilateral conjunctival erythema and a mild serous exudate. The lungs are clear to auscultation. Which of the following viruses is the most likely cause of this child's illness?
A. Adenovirus
B. Mumps virus
C. Parvovirus
D. Respiratory syncytial virus
E. Rhinovirus
F. Rotavirus
14. Cells from a pancreatic carcinoma express very small amounts of class I MHC molecules and are resistant to recognition and killing by CD8+ T lymphocytes isolated from the host individual. Substantial tumor cell lysis is observed when these cells are cultured in the presence of a mixed leukocyte population isolated from the peripheral blood of a normal (cancer-free) individual. Which of the following leukocytes in the blood of the normal individual are most likely responsible for the in vitro lysis of the tumor cells?
A. B-lymphocyte effector (plasma) cells
B. CD4+ T lymphocytes
C. CD8+ T lymphocytes
D. Eosinophils
E. Macrophages
F. Natural killer cells
G. Neutrophils
15. A 4-year-old boy develops uncontrolled bleeding after minor trauma. He has a history of recurrent sinopulmonary infections and eczematous rashes. Which of the following predisposing conditions is most likely present?
A. Bruton agammaglobulinemia
B. Common variable immunodeficiency
C. Selective IgA deficiency
D. Thymic hypoplasia
E. Wiskott-Aldrich syndrome
16. A 3-year study is planned to assess the incidence and etiology of respiratory disease in 574 individuals greater than age 60. The study population consists of two groups: one group cares for children under the age of 5; the second group does not care for children. At the onset of respiratory symptoms, cultures and serologic studies will be performed. Which of the following best describes this study design?
A. Case-control
B. Case series
C. Clinical trial
D. Cohort
E. Community survey
17. The graph shows the oxygen dissociation curve of hemoglobin A for a healthy individual. Which of the following curves best represents the dissociation curve for the same individual after extensive physical training at high altitudes?
A. A
B. B
C. C
D. D
18. A 68-year-old woman has a pathologic fracture of the hip. A photomicrograph of tissue obtained on aspiration of bone marrow is shown. Which of the following is the most likely diagnosis?
A. Acute myelogenous leukemia
B. Chronic lymphocytic leukemia
C. Langerhans cell histiocytosis
D. Metastatic adenocarcinoma
E. Multiple myeloma
19. A 40-year-old woman comes to the physician because of "too much stress in my life now." She describes feeling depressed and tense because of a recent marital separation, a job change, the need to relocate to another city, and the worsening of her 8-year-old son's asthma. Physical examination shows no abnormalities. Laboratory studies are most likely to show which of the following abnormalities?
A. Decreased lymphocyte reactivity to antigens
B. Decreased serum prolactin concentration
C. Increased serum calcium concentration
D. Increased serum thyroid-stimulating hormone concentration
E. Mild normochromic, normocytic anemia
20. A 74-year-old woman has a stroke that results in weakness of the left hand and forearm. Which of the following arteries is most likely occluded?
A. Left anterior cerebral
B. Left middle cerebral
C. Right anterior cerebral
D. Right middle cerebral
21. A 45-year-old woman has weakness in the anterior thigh and is unable to extend her leg at the knee. Flexion of the hip and knee is normal. Sensation is absent on the medial side of the leg. Which of the following nerves is most likely injured?
A. Common peroneal
B. Femoral
C. Lumbosacral trunk
D. Obturator
E. Tibial
22. An unimmunized 2-year-old girl is brought to the emergency department after having a generalized tonic-clonic seizure. She has had a fever and an upper respiratory tract infection for the past 4 days. A Gram stain of cerebrospinal fluid shows numerous gram-negative coccobacilli. Which of the following vaccines would most likely have prevented this infection?
A. DTP
B. Hib
C. Meningococcal
D. Pneumococcal
E. Salmonellal
23. A 6-year-old boy falls off his bicycle and hits his head; he has a transient loss of consciousness. After a brief recovery, he becomes progressively more somnolent. On examination, he has weakness in the right side of the face and right upper extremity. CT scan of the head is shown. The injury at the site labeled X is a consequence of rupture of which of the following arteries?
A. Anterior cerebral
B. Anterior choroidal
C. Anterior communicating
D. Middle cerebral
E. Middle meningeal
24. A 45-year-old man has had generalized jerking movements in his extremities, progressive dementia, and psychotic behavior for the past year. His mother died of a similar illness when she was 50 years old. A CT scan of the head is most likely to show atrophy of which of the following areas of the brain?
A. Caudate nucleus
B. Globus pallidus
C. Hippocampus
D. Putamen
E. Substantia nigra
25. A 22-year-old woman is brought to the emergency department by police after they found her walking naked down the middle of the street. She is screaming that the police are planning to hurt her and that they are members of a secret society that has been following her for months. She is not cooperative with history taking and says quickly, "Plants aren't often watered. Those doorknobs need polishing. Where's the merry-go-round?" She is emaciated, dirty, and disheveled. Laboratory studies show mild microcytic anemia. Urine toxicology screening is negative. Which of the following is the most likely diagnosis?
A. Adjustment disorder with disturbance of conduct
B. Dissociative fugue
C. Schizophreniform disorder
D. Schizotypal personality disorder
E. Substance-induced mood disorder
26. A 3-year-old girl is brought to the emergency department by her parents 10 minutes after they found her playing with an empty medication bottle. The bottle had contained 60 tablets of diazepam. Physical examination and laboratory studies show no abnormalities. This patient is at greatest risk for which of the following complications?
A. Acute tubular necrosis
B. Cardiac arrhythmia
C. Hepatic failure
D. Respiratory depression
E. Seizures
27. A 16-year-old boy is brought to the physician because he is much shorter than his peers. He is proportionally developed and otherwise healthy. An x-ray of the wrist is recommended to assess bone age. Which of the following radiographic findings will be an indication that his growth is complete?
A. Absence of the epiphyseal cartilaginous plate
B. Absence of the primary ossification center
C. Presence of calcified material in the diaphysis
D. Presence of calcified material in the epiphysis
E. Presence of lines of arrested growth
28. A 30-year-old woman who is menstruating develops tenderness of the right knee. She has had arthralgias involving her wrists and knees for the past 3 days. She has no urinary tract symptoms or vaginal discharge. The right knee is swollen and warm to the touch. Approximately 10 necrotic pustules are present on her upper and lower extremities. A Gram stain of scrapings from the cervical os is shown. Which of the following is the most likely causal organism?
A. Calymmatobacterium donovani
B. Chlamydia trachomatis
C. Haemophilus ducreyi
D. Neisseria gonorrhoeae
E. Neisseria meningitidis
29. A 48-year-old man with chronic pancreatic insufficiency develops greasy, foul-smelling stools. He has lost 12 kg (26 lb) over the past 6 months. Which of the following is most likely to be decreased in this man?
A. Chondrocyte formation of type I collagen
B. Mineralization of bone matrix
C. Osteoclast production of carbonic anhydrase II
D. Osteocyte production of alkaline phosphatase
E. Urinary excretion of hydroxyproline
30. A 10-year-old boy is being evaluated because of poor growth, recurrent episodes of sinusitis, and a chronic cough. An x-ray of the chest shows evidence of bronchiectasis. A rare inherited disorder causing immotile, structurally abnormal cilia in the respiratory epithelium is diagnosed. This patient's impaired mucociliary clearance is most likely to predispose him to pulmonary infections with which of the following infectious agents?
A. Candida albicans
B. Cryptococcus neoformans
C. Cytomegalovirus
D. Mycobacterium avium-intracellulare
E. Staphylococcus aureus
31. A previously healthy 30-year-old man comes to the emergency department because of the sudden onset of right shoulder pain and shortness of breath. Breath sounds are absent over the right lung. His cervical trachea at the superior sternal border is shifted to the left. The most likely cause of his condition is rupture of which of the following?
A. Anterior hernia
B. Apical pulmonary bleb
C. Bronchial diverticulum
D. Cystic adenomatoid malformation
E. Posterolateral hernia
32. A 40-year-old man who works in a gravel pit is brought to the emergency department after being hit in the chest by a slab of cement. He does not smoke and does not have a cough. An x-ray of the chest does not show any fractures, but multiple small nodules are seen, some of which are calcified, in the upper lobes. A PPD skin test is negative. Which of the following is the most likely diagnosis?
A. Asbestosis
B. Berylliosis
C. Byssinosis
D. Industrial bronchitis
E. Silicosis
33. A 60-year-old man comes to the physician for a follow-up examination. He had a myocardial infarction of the right ventricle 3 weeks ago. Physical examination shows an accumulation of free fluid in the peritoneal space. Which of the following mechanisms is the most likely cause of this finding?
A. Decreased capillary colloid osmotic pressure
B. Increased capillary hydrostatic pressure
C. Increased capillary permeability
D. Increased lymphatic colloid osmotic pressure
E. Lymphatic obstruction
34. A 65-year-old man comes to the physician because of recurrent lightheadedness. His ECG is shown. Which of the following is most likely responsible for the abnormal ECG pattern in this patient?
A. Atrioventricular conduction disease
B. Atrioventricular re-entrant pathway
C. Ectopic focus in the atria
D. Ectopic focus in the ventricle
E. Sinus node disease
35. An 18-month-old boy is brought to the physician's office for a follow-up cardiac examination. He has a continuous, grade 3/6, rumbling, machinery-like murmur that is heard best at the mid to upper left sternal border. Which of the following is the most likely diagnosis?
A. Mitral valve regurgitation
B. Ostium primum defect
C. Ostium secundum defect
D. Patent ductus arteriosus
E. Sinus of Valsalva fistula
F. Ventricular septal defect
36. A previously healthy 65-year-old man is brought to the emergency department because of severe chest pain for 1 hour. His pulse is 95/min, and blood pressure is 160/110 mm Hg. The lungs are clear to auscultation. An S4 gallop and a grade 2/6 systolic murmur are heard at the apex. An ECG shows 3 mm of ST-segment elevation in leads V2 through V5. The most appropriate treatment includes immediate administration of which of the following?
A. Captopril
B. Digoxin
C. Furosemide
D. Magnesium
E. Tissue plasminogen activator
37. Which of the following hormones, produced by the duodenal and proximal jejunal mucosa, stimulates the release of pancreatic juice rich in digestive enzymes?
A. Cholecystokinin
B. Glucagon
C. Pancreatic polypeptide
D. Secretin
E. Vasoactive intestinal polypeptide
38. An asymptomatic 56-year-old woman has occult blood in her stool. Barium studies of her transverse colon show an intraluminal mass. The surgical specimen is shown. Which of the following is the most likely diagnosis?
A. Adenocarcinoma
B. Carcinoid tumor
C. Polypoid leiomyoma
D. Tubular adenoma
E. Villous adenoma
39. A 94-year-old man has been taking ibuprofen for osteoarthritis for the past 5 years. Two years ago, he developed renal failure, and serum creatinine concentration increased from 1.2 to 2.0 mg/dL. He recently developed gastrointestinal hemorrhage from a gastric ulcer. He wants to continue taking the ibuprofen. Which of the following drugs is most likely to decrease this patient's risk for ibuprofen-induced gastric ulceration?
A. Ampicillin
B. Metronidazole
C. Misoprostol
D. Sucralfate
E. Vitamin B6 (pyridoxine)
40. Which of the following procedures is most likely to increase serum aldosterone concentrations in an experimental subject?
A. Administration of an angiotensin-converting enzyme inhibitor
B. Increase in sodium intake
C. Inhibition of ACTH secretion
D. Intravenous administration of 0.9% saline
E. Restriction of water intake
41. A 65-year-old woman is brought to the emergency department because of lethargy and confusion for 24 hours. She did not fall or injure herself recently. Medications include amitriptyline (150 mg at bedtime) for major depressive disorder and diphenhydramine for the past week (50 mg 3 times daily) for a pruritic rash. Her pulse is 100/min and regular, and blood pressure is 135/80 mm Hg. Physical examination shows a palpable mass in the midline extending 5 cm upward from the pubic symphysis. Her serum urea nitrogen (BUN) concentration is 45 mg/dL, and serum creatinine concentration is 2.8 mg/dL. Which of the following best explains the laboratory results?
A. Acute tubular necrosis
B. Bilateral renal artery stenosis
C. Bilateral ureteral obstruction just distal to the renal pelvis
D. Bilateral ureteral obstruction proximal to the bladder
E. Constrictive pericarditis
F. Decreased ability to empty the bladder
G. Interstitial nephritis
42. A 4-year-old boy is being evaluated for renal calculi. Urinalysis shows numerous hexagonally shaped crystals. Urine concentrations of several amino acids, including ornithine, arginine, and lysine, are increased. Which of the following is the most likely predominant component of the crystals?
A. Calcium oxalate
B. Cholesterol
C. Cystine
D. Struvite
E. Uric acid
43. An otherwise healthy 48-year-old woman comes to the physician because of a change in her menstrual pattern. Her last normal menstrual period was 4 months ago, and she noticed scant staining 3 weeks ago. Her history is otherwise unremarkable. Physical examination shows vaginal dryness. Laboratory evaluation is most likely to show which of the following changes in serum hormone concentrations?
A. Decreased follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
B. Decreased serum prolactin
C. Decreased serum thyroxine (T4)
D. Increased FSH and LH
E. Increased serum prolactin
F. Increased serum T4
44. A 1-year-old child has unilateral cryptorchidism. Even if this problem is surgically corrected, the patient will be at increased risk for development of which of the following in the cryptorchid testis?
A. Germ cell neoplasm
B. Leydig cell tumor
C. Recurrent orchitis
D. Spermatocele
E. Testicular torsion
45. A 33-year-old woman, gravida 2, para 1, at term gives birth to a 4167-g (9 lb 3 oz) male newborn by a spontaneous 30-minute vaginal delivery. Shortly after delivery of the placenta, there is a brisk flow of blood from the uterus. Manual palpation of the uterine cavity shows a large fragment of retained placental material. A curettage shows a fibrous nodule of placental tissue that is firmly adherent to the uterine wall. Which of the following is the most likely cause of the bleeding in this patient?
A. Abruptio placentae
B. Choriocarcinoma
C. Factor XIII (transglutaminase) deficiency
D. Granulomatous endometritis
E. Placenta accreta
F. Placenta previa
46. An 8-year-old boy is brought to the pediatrician's office because of a painful lump on his neck for the past 3 days. Examination shows a 3-cm, tender, rounded, cystic mass in the anterior midline, midway between the chin and sternal notch. The mass elevates with swallowing. Which of the following best explains this finding?
A. Failed differentiation of the third pharyngeal pouch
B. Hypertrophy of the lingual tonsils
C. Incomplete atrophy of the thyroglossal duct
D. Maldevelopment of the first branchial arch
E. Persistence of the second branchial groove
47. A 55-year-old man has had decreasing interest in sex over the past 2 years and impotence for the past 6 months. He has frequent headaches. Examination shows bitemporal visual field defects, sparse facial and pubic hair, and testicular atrophy. MRI shows a 3-cm pituitary tumor. Which of the following sets of serum hormone concentrations is most likely?
Luteinizing Hormone Testosterone
A ↑ ↑
B ↑ ↓
C Normal Normal
D ↓ ↑
E ↓ ↓
48. A 6-month-old male infant is sluggish and appears edematous. He has coarse immature facies and poor muscle tone. Which of the following is the most likely diagnosis?
A. Achondroplasia
B. Congenital hypothyroidism
C. Diastrophic dwarfism
D. Multiple cartilaginous exostoses
E. Muscular dystrophy
F. Myasthenia gravis
G. Osteogenesis imperfecta
H. Tay-Sachs disease
I. Vitamin D-deficiency rickets
49. A 68-year-old man with benign prostatic hypertrophy starts taking terazosin. Which of the following changes is most likely in second messenger levels in the cells affected by this treatment?
A. Decrease in cyclic AMP
B. Decrease in cyclic GMP
C. Decrease in IP3
D. Increase in cyclic AMP
E. Increase in cyclic GMP
F. Increase in IP3
50. After undergoing a minor surgical procedure, a 71-year-old man has difficulty voiding. Which of the following is the most appropriate short-term pharmacotherapy?
A. Atropine
B. Bethanechol
C. Edrophonium
D. Physostigmine
E. Scopolamine