Nbme 13 pdf download

A pedigree is shown. Which of the following genetic principles best explains the findings in this family? A Anticipation. A catheter is placed in the left and right renal veins to sample the effluent. The concentration of which of the following substances will most likely be higher in the effluent from the left renal vein than that from the right renal vein?

A previously healthy year-old man is brought to the emergency department because of a 1-day history of intermittent flashing spots and blurred vision, vomiting, confusion, and difficulty walking. He is a painter and says that yesterday he cleaned up a spilled bottle of paint thinner. Ophthalmologic examination shows dilated pupils with hyperemia of the optic disc and retinal edema.

Physical examination shows tachypnea. Serum studies show an anion gap metabolic acidosis. The most appropriate pharmacotherapy for this patient is most likely to inhibit the activity of which of the following? A year-old man is brought to the emergency department because of difficulty opening his mouth and stiffness of his neck, shoulders, and back for 4 hours.

He sustained a puncture wound to his arm 1 week ago. He has received no medical care for 30 years. Physical examination shows trismus and opisthotonos. Which of the following best describes the process in this patient? A Blockade of inhibitory neurotransmitter release B Cell death in central nervous system neurons C Cell death in muscles D Cell death in peripheral nervous system neurons O E Demyelinization. A year-old woman is brought to the emergency department because of a 3-hour history of severe headache, slurred speech, and confusion.

She has a 2-year history of atrial fibrillation. She has difficulty understanding and answering questions, but she is cooperative. Ophthalmologic examination shows hemianopia and a tendency to gaze to the right. The pupils are normal sized and reactive to light. Neurologic examination shows left-sided numbness and paralysis that are more severe in the face and upper extremity than in the lower extremity. Which of the following arteries is most likely involved in this patient's condition?

A year-old woman comes to the physician because of a 5-day history of severe mid-back pain. Physical examination shows point tenderness over the T6 vertebra. Serum studies show a calcium concentration of Which of the following is the most likely cause of this patient's hypercalcemia? A Excessive parathyroid hormone production B Excessive parathyroid hormone-related protein production C Increased fractional calcium gastrointestinal absorption O D Local interleukin-1 IL-1 and tumor necrosis factor effects E Unregulated 1,dihydroxycholecalciferol production.

A male newborn is delivered at 38 weeks' gestation following an uncomplicated pregnancy. Twelve-hours later, he begins sucking frantically and crying inconsolably. He overreacts to stimuli around him and has a marked startle response.

The symptoms slowly resolve over the next 2 to 3 weeks. The most likely explanation for these symptoms is maternal use of which of the following substances during pregnancy? A year-old woman comes to the physician because of a 2-year history of sporadic double vision and a 1-year history of intermittent numbness and tingling in her arms.

The symptoms became more severe 5 days ago after a 4-day visit from her husband's parents. During the past year, she also has had four episodes of urinary incontinence.

Physical examination shows mild dysarthria. On mental status examination, she has a mildly worried mood and a reactive affect. MRI of the brain shows a few small, scattered, nonspecific white-matter plaques. A Complex partial seizure disorder. A year-old woman, gravida 2, para 2, develops severe vaginal bleeding immediately after vaginal delivery of a male newborn at term.

The hemorrhage continues during the next hour, and the patient undergoes an emergency hysterectomy to control the bleeding. Examination of the uterus shows fragments of placenta adherent to the uterine wall. There is absence of the decidua basalis. A year-old man with hepatic encephalopathy is brought to the physician because of confusion and increased lethargy during the past 24 hours. He has a history of cirrhosis of the liver caused by hepatitis C. He is easily arousable despite the lethargy.

His temperature is 37C Physical examination shows scleral icterus, asterixis, a protuberant abdomen, and ascites. Test of the stool for occult blood is negative. Administration of which of the following drugs is most likely to improve this patient's mental status? A year-old man is admitted to the hospital because of a 2-week history of a persistent urinary tract infection. The physician plans to initiate treatment. The volume of distribution of the antibiotic is 0. Laboratory studies show a hour urine creatinine clearance within the reference range.

Which of the following is the most appropriate loading dose of this drug for this patient in mg? A healthy year-old man is a subject in a study investigating the regulation of heart rate during exercise. He is sitting on a stationary bicycle and is instructed to begin pedaling in 5 minutes.

One minute before he begins to pedal, his heart rate increases. An increase in which of the following transmitters acting at the indicated receptor best explains the increase in heart rate in this man?

A year-old boy has intracranial neoplasms, mental retardation, and seizures associated with tuberous sclerosis complex, an autosomal dominant disorder. His year-old mother is healthy but has angiofibromas, which are benign skin lesions characteristic of tuberous sclerosis complex.

Which of the following best explains the findings in the boy and his mother? A year-old woman is brought to the emergency department 30 minutes after sustaining severe chest injuries in a motor vehicle collision. Despite appropriate treatment, she dies 1 hour later. She had a year history of a wellcontrolled seizure disorder. A photograph of a coronal section of the brain obtained at autopsy is shown. Which of the following is the most likely cause of this patient's seizure disorder?

A year-old man comes to the physician because of a 2-week history of cough productive of blood. He also has had a 3-kg 6. He has smoked 2 packs of cigarettes daily for 32 years. He has hypertension treated with metoprolol. Physical examination shows clubbing of the fingernails. Wheezes are heard over the right upper lobe anteriorly; there are no crackles. A CT scan of the chest shows a 2. This patient's laboratory findings are most likely caused by an excess of which of the following hormones?

A year-old man comes to the physician because of weakness and light-headedness for 3 months. His diet consists of a healthy balance of fruits, vegetables, whole grains, and lean chicken and fish. He has a year history of chronic autoimmune Hashimoto thyroiditis treated with thyroxine. Physical examination shows pallor. Serum studies show increased concentrations of methylmalonic acid and total homocysteine.

A peripheral blood smear shows megaloblastic anemia. Which of the following is the most likely cause of the findings in this patient? A Cystathionine 3-synthase deficiency. A year-old woman is scheduled to undergo transvaginal hysterectomy and oophorectomy for dysfunctional uterine bleeding.

During the procedure, the uterus must be separated from all surrounding pelvic structures. Identification and incision of which of the following structures that attaches to the cervical region and extends posteriorly is most appropriate in this patient? A year-old woman comes to the physician because of a kg lb weight gain during the past 6 months despite dieting.

Physical examination shows a round, ruddy face with hirsutism, excess weight predominantly in the shoulders and abdomen, and purple striae over the abdomen. An MRI shows a mass in the pituitary gland. A CT scan of the abdomen shows enlarged adrenal glands. Which of the following histologic changes would be expected in this patient's adrenal glands? A Cortical hyperplasia. A year-old woman comes to the physician for a follow-up examination. One year ago, she was diagnosed with a pulmonary embolism.

Two years ago, she delivered a female stillborn at 23 weeks' gestation. Physical examination today shows no abnormalities.

The findings in this patient are most consistent with which of the following conditions? A year-old man comes to the physician because of a 2-week history of burning epigastric pain. He is recently divorced. His diet mainly consists of fast food. He smokes cigars and drinks one to two ounce cans of beer on the weekends. He was treated for Helicobacter pylori infection 1 year ago. He uses high doses mg daily of over-the-counter ibuprofen for chronic joint pain. Abdominal examination shows tenderness to deep palpation of the epigastric area.

A peptic ulcer is suspected. Which of the following is the strongest predisposing risk factor for this patient's condition? A year-old nulligravid woman comes to the physician because she has been unable to conceive for 18 months. She has had irregular menses since menarche at the age of 13 years.

Her temperature is Physical examination shows moderate hirsutism and mild acne over the face and back. Pelvic examination shows no abnormalities of the exterior genitalia; a bimanual examination is limited by the patient's obesity. Which of the following is the most likely cause of this patient's infertility? A 9-year-old girl is brought to the emergency department by her father because of severe pain in her right shoulder after a fall 1 hour ago.

Physical examination shows pain on movement of the right shoulder and a tender right clavicle. An x-ray of the shoulder shows a nondisplaced fracture of the right clavicle. Which of the following structures of the clavicle will most likely assist in producing new bone to heal this fracture? A 2-month-old boy dies of meningitis despite appropriate antibiotic therapy.

Culture of his cerebrospinal fluid grows mycobacterial infections. Which of the following immunodeficiencies most likely explains this familial history?

A previously healthy year-old man is admitted to the hospital for treatment of viral pneumonia. He is mechanically ventilated because of respiratoryfailure due to hypoxemia.

An openlung biopsy specimen is obtained and shows a pattern of acute lung injury. The presence of which of the following in the biopsy specimen most clearly suggests diffuse alveolar damage rather than bronchiolitis obliterans-organizing pneumonia in this patient?

A year-old woman with end-stage renal disease caused by systemic lupus erythematosus undergoes kidney transplantation from a living, unrelated donor. Despite aggressive immunosuppressive therapy, the transplant is rejected after 6 months. Which of the following is the most likely cause of rejection of the transplant in this patient? A 7-year-old girl is brought to the physician by her parents because of a 3-year history of temper tantrums when her parents leave her.

She refuses to sleep alone and recently would not attend her friend's birthday slumber party. She calls to her mother if she is in another room of the house. Each morning, the patient's teacher has to carry her into school crying. Her mother recently returned to work full-time and says that she is quite angry that her daughter is behaving in such a defiant way.

Her father recalls that he behaved the same way when he was her age. Which of the following is the most likely explanation for this patient's behavior? A year-old man with pancreatic cancer undergoes a Whipple procedure to resect the distal stomach, duodenum, and head of the pancreas. During the procedure, the cut end of the remaining stomach is joined to the side of the jejunum gastrojejunostomy.

Which of the following nerve structures can be cut to decrease stomach acid output and decrease the likelihood of ulcers forming in the jejunum at the site of junction with the stomach? A year-old man comes to the physician for a routine examination. He has a 5-year history of recurrent episodes of genital herpes treated with acyclovir. He says, "I've been taking the medication, but I still occasionally get lesions. When will I be cured? Which of the following best explains the longevity of the herpes simplex virus?

A Continual replication in dendritic cells B Continual replication in epithelial cells of the skin C Continual replication in sacral root ganglia D Continual replication in T lymphocytes E Establishment of a latent infection in B lymphocytes F Establishment of a latent infection in circulating immune cells G Establishment of a latent infection in epithelial cells of the skin H Establishment of a latent infection in sensory nerve cells. A 3-year-old boy is brought to the emergency department because of multiple ecchymoses, bleeding into the joints, and bloody diarrhea 48 hours after ingesting an unknown quantity of warfarin that he took from his grandmother's purse.

Which of the following is the most appropriate initial therapy? An year-old man comes to the physician 6 hours after he twisted his ankle while playing football. Physical examination shows looseness of the lateral collateral ligament, suggestive of a tear.

Lack of which of the following components in the ligament will most likely limit healing of this injury? A previously healthy 6-year-old girl is brought to the emergency department because of severe abdominal pain, nausea, and vomiting that began 4 hours after attending a friend's birthday party. Cake and other pastries were served at the party. She appears acutely ill and mildly dehydrated. Examination shows no abnormalities of the skin. Bowel sounds are hyperactive.

Which of the following is the most likely cause of these findings? A year-old woman comes to the physician for a health maintenance examination. During the interview, she tearfully tells the physician that she and her new husband are having problems. She says she wants to go out with friends, but he does not enjoy being with people, preferring individual activities such as hiking.

She says he seems indifferent to sexual intimacy and neither shows much emotion nor understands her feelings at all. Which of the following personality styles best explains the husband's behavior? A year-old woman is treated with acetazolamide to prevent acute altitude sickness 3 days before going on a mountain-climbing expedition. Acetazolamide acts predominately in which of the following areas of the kidney in this patient?

A study is conducted to assess the effectiveness of vitamin C in preventing common colds in children. Patients are randomly assigned to receive either vitamin C or no intervention. Outcome events common cold are reported by the parents on a monthly basis for 1 year. Which of the following raises the most concern about the validity of the conclusion that vitamin C supplements prevent the common cold?

A Inadequate statistical power. A healthy year-old man dies suddenly of cardiac arrest after snorting cocaine. Cocaine-induced inhibition of which of the following is the most likely explanation for the cardiac arrest? A Acetylcholinesterase. A year-old man is brought to the emergency department because of a 3-hour history of progressive difficulty breathing and mild left shoulder pain. His symptoms began after he ran up several flights of stairs.

He has poorly controlled hypertension and mild angina pectoris. He has smoked one-half pack of cigarettes daily for 40 years. He appears uncomfortable and has labored breathing.

Diffuse crackles, rhonchi, and scattered wheezing are heard on auscultation of the posterior lung fields. His arterial Po2 is 58 mm Hg. A Cardiac tamponade. A year-old woman is admitted to the hospital because of a day history of polydipsia and polyuria.

She says that the urge to urinate often awakens her at night. She has been taking lithium carbonate for 2 years for bipolar disorder; her dosage was increased 6 months ago because of recurrent severe manic episodes. Over the next 24 hours, urine excretion totals 6. After administration of desmopressin, urine output and osmolality do not change.

Which of the following findings in the nephron best describes the tubular osmolality, compared with serum, in this patient? Juxtaglomerular Apparatus hypertonic hypertonic hypotonic isotonic hypotonic hypotonic hypertonic hypotonic hypotonic. Medullary Collecting Duct hypertonic hypotonic hypotonic isotonic hypertonic hypotonic hypertonic hypertonic hypotonic. An year-old woman is admitted to the hospital for treatment of a smallright pleural effusion. Physical examination showsdullness to percussion at thelevel of the 7th rib and below on the right.

A thoracentesis is done. The patient is sitting up, supportedby leaning against abedside table. After preparing the skin and deliveringa local anesthetic,into which of the following locations on the right is it most appropriate to insert the catheter?

O A Above the 5th rib in the midscapular line B Above the 5th rib just to the right of the sternum C Above the 7th rib in the paravertebral region D Above the 9th rib in the midscapular line O E Below the 5th rib in the midaxillary line F Below the 5th rib in the midclavicular line G Below the 9th rib in the midscapular line. A year-old woman is admitted to the intensive care unit after undergoing immediate operative repair of a ruptured colonic diverticulum.

During the next 2 weeks, she develops recurrent fevers. After a blood culture grows yeast, micafungin therapy is initiated. This drug most likely targets which of the following cellular structures? A year-old woman comes to the physician because of a 1-day history of chills, nausea, and vomiting. She also has a 4-day history of flank pain, urinary frequency and urgency, and pain with urination. Physical examination shows right costovertebral angle tenderness. A urine sample grows pink colonies on lactose-MacConkey agar, produces a characteristic green sheen on eosin-methylene blue agar, and is indole positive.

The production of which of the following by the bacterium aids in the virulence of the causal organism in this patient? A year-old woman at 32 weeks' gestation is brought to the physician because of a 2-day history of fever, nausea, vomiting, and muscle aches. She appears acutely ill. Her temperature is 39C A photomicrograph of a Gram stain of an organism recovered from a blood culture is shown. Which of the following is the most likely causal organism? A year-old woman who is a medical student comes to the physician for evaluation of recurrent throbbing headache associated with sensitivity to light and sound.

Neurologic examination shows no abnormalities. Sumatriptan is initiated for suspected migraine. This drug is most appropriate for this patient because of its ability to activate which of the following types of receptors? A 5-year-old girl is brought to the physician because of listlessness, fatigue, and dull pain in the right upper quadrant of the abdomen. Her height and weight are below the 25th percentile. An investigator breeds a transgenic strain of mice that develops severe fasting hypoglycemia.

Administration of glucagon does not correct the hypoglycemia, but administration of epinephrine results in an increase in the serum glucose concentration. Which of the following proteins is most likely defective in this mouse strain? A year-old man comes to the physician because of progressive weakness of his hands during the past 6 months. He works as a carpenter and has had difficulty handling his tools.

He has smoked 1 pack of cigarettes daily for 45 years. He drinks two beers daily during the workweek and approximately six beers daily on weekends. Physical examination shows no lymphadenopathy. He has diffuse hyperreflexia. Fasciculations are noticed on the muscles of the hands and upper extremities.

Sensory examination is normal. Over the course of this disease, which of the following findings is most likely? A year-old man has had episodes of fluctuating weakness for the past 2 years. The weakness was first noticed when he had difficulty lifting books. At times, he has had drooping of the eyelids and double vision.

Recently, he has had difficulty climbing stairs and regurgitation of liquids into his nose. On physical examination, the weakness increases with repeated exercise. An x-ray of the chest shows a mass in the mediastinum. Which of the following laboratory assays is most likely to be positive? A 3-year-old girl is brought to the emergency department by her mother 1 hour after she was found with a half-empty bottle of her grandmother's diabetes medication. The mother tells the physician that the child consumed approximately 25 metformin tablets.

This patient is at greatest risk for which of the following serum abnormalities? A year-old woman with diabetic ketoacidosis has had a fever and proptosis of the left eye over the past 3 days.

She is unable to move the left eye. A black eschar is present on the nasal mucosa. A year-old man comes to the physician because of a 4-week history of muscle cramping and pain. Two months ago, he began treatment with simvastatin 80 mg daily for hypercholesterolemia. After 1 month, marked improvement was noted in his serum LDL-cholesterol concentration, but serum triglyceride concentration remained increased.

At that time, gemfibrozil was added to his regimen to decrease his triglyceride concentration. This patient's myalgia is most likely related to which of the following effects of gemfibrozil on simvastatin? A year-old woman comes to the physician because of a 2-day history of decreasing urine output despite ample fluid intake. She underwent operative removal of a perforated appendix 3 weeks ago.

She received intravenous gentamicin for 2 weeks. Histologic examination of this patient's kidneys would most likely show necrotic cells in which of the following components of the nephron? A year-old man comes to the physician because he is concerned about his weight. His waist circumference is cm 41 in. Physical examination shows a protuberant abdomen. Laboratory studies show fasting serum glucose and insulin concentrations that are increased and remain increased 2 hours after the patient receives 75 g of oral glucose.

Which of the following sets of additional laboratory findings in serum is most likely in this patient? A year-old man is brought to the emergency department 3 hours after the sudden onset of sharp left flank pain and fever.

He has had similar episodes during the past 5 years. His temperature is Abdominal examination shows exquisite tenderness in the left costovertebral region.

Imaging studies show hydronephrosis of the left kidney and a staghorn calculus. A nephrectomy is done; the calculus is composed of magnesium ammonium phosphate struvite. Culture of a urine sample is most likely to grow which of the following organisms? A year-old man comes to the physician for a routine health maintenance examination.

Physical examination and laboratory studies show no other abnormalities. He tells the physician, "My older brother just got diagnosed with diabetes. I don't want that to happen to me. What should I do? An year-old primigravid woman at approximately 16 weeks' gestation comes to the physician because of a 3-month history of nausea and vomiting. She has not had any prenatal care. Physical examination shows a uterus consistent in size with a week gestation.

Her serum 3-human chorionic gonadotropin concentration is markedly increased. Ultrasonography of the abdomen shows echogenic material within the endometrial cavity but no fetus.

The most likely cause of her condition is proliferation of which of the following? A previously healthy year-old man comes to the clinic because of light-headedness for 6 hours.

His symptom began after skiing at a resort at an altitude of m ft. He has been taking a carbonic anhydrase inhibitor since 2 days before arrival at the resort. Physical examination shows no other abnormalities. Which of the following is the most likely cause of his orthostatic hypotension?

A year-old man comes to the physician because of a 3-day history of fever and shaking chills. He has end-stage renal disease treated with hemodialysis.

Physical examination shows a tunneled central venous catheter entering the right side of the chest below the clavicle; the area surrounding the catheter is not tender. Echocardiography shows a 3-cm vegetation on the tricuspid valve. A year-old woman comes to the physician because of a 3-week history of numbness of the fingers on the left hand.

Neurologic examination shows loss of touch graphesthesia and loss of two-point discrimination in the left hand. This patient most likely has a lesion in which of the following locations of the hemispheres shown?

A year-old woman with a 1-year history of diabetes mellitus has had decreasing vision over the past year. Examination of the eyes shows milky opacity of both lenses. Which of the following aberrant metabolites of glucose is most likely responsible for the formation of this abnormality? A year-old woman comes to the physician 3 months after she noticed a painless, slowly enlarging mass on the left side of her neck.

Physical examination shows a freely mobile, soft, cystic mass with a cutaneous surface opening. The physician explains that it is from incomplete fusion during embryonic development.

Which of the following is the most likely location of the opening of the duct leading to the mass in this patient? In a healthy person, the thyroid gland produces and secretes thyroxine T4 , maintaining metabolism. Which of the following best describes the T4 -binding substance in the blood and the type of cellular receptor for T 4 in the peripheral tissues?

Receptor That Interacts With T4in the Peripheral Tissues cell membrane receptor mitochondrial nuclear cell membrane receptor mitochondrial nuclear. A year-old man has an autoimmune disorder resulting in proximal muscle weakness of the lower extremities. Arrows in the photomicrograph shown indicate membranes that contain high concentrations of channels that are targeted by this condition.

A Multiple sclerosis B Myasthenia gravis o Previous. A year-old man comes to the emergency department because of a 1-year history of low back pain. Before the examination, the patient says, "My physician is arrogant and insensitive.

He never returns my phone calls, I always have to wait forever to be seen, the tests he orders are painful and unnecessary, and he can never tell me what is causing my back pain or how to treat it.

A Reassure the patient that his physician's behavior is not unusual and that low back pain can be difficult to assess B Encourage the patient to make an appointment with his physician to communicate his concerns C Explain to the patient how he may register a complaint against his physician with the state medical licensing board D Provide the patient with a copy of the Patients' Bill of Rights E Telephone the patient's physician to make him aware that the patient is very dissatisfied with treatment.

A year-old man recovered from a stroke 2 months ago. He lives alone. He is at increased risk for which of the following psychiatric disorders? A year-old man with a 1-year history of angina pectoris comes to the emergency department because of increasingly severe chest pain during the past 2 days.

He has had five previous similar episodes, which required treatment with increasing doses of nitroglycerin to resolve. Cardiac examination shows an S 4. This antibody will most likely prevent binding of which of the following substances to platelets? A year-old woman has a 2-week history of a heart murmur and hepatomegaly. She has a 3-month history of flushing with hypotension and crampy diarrhea. Which of the following is the most likely site of a primary neoplasm in this patient?

A Adrenal gland. A year-old woman dies in the hospital after a long illness. Her vertebral column, obtained at autopsy, is shown in the photograph. The process shown is most likely associated with an increase in which of the following? Two clinical trials, Trial X and Trial Y, are conducted to assess the potential therapeutic efficacy of a new experimental antibiotic compared to the currently used antibiotic for treatment of urinary tract infections.

The two studies are identical, except the statistical power is 0. Which of the following is the most accurate conclusion regarding the likelihood of a type II error? A 3-year-old boy with a history of unexplained fever, lack of perspiration, absence of response to noxious stimuli, and self-mutilating behavioris diagnosed withcongenital insensitivity to pain with anhidrosis. Genetic analysis shows a missense mutation of the tyrosine kinasedomain of the TrkA gene. Assuming this is theonly signaling defectin this patient, which of the following processes has most likely been disrupted?

O A Binding of nerve growth factor to its receptor B Formation of TrkA homodimer in response to nerve growth factor C Phosphorylation of downstream molecules in response to nerve growth factor D Retrograde transport of nerve growth factor from nerve terminals O E Synthesis of nerve growth factor.

A 4-year-old boy is brought to the emergency department because of a 1-hour history of headache, nausea and vomiting, and dizziness.

Physical examination shows severe lethargy. Which of the following steps in the electron transport pathway is primarily affected in this patient? A Reduced substrate , n -t. A year-old woman has had pain, swelling, and stiffness in both hands over the past 6 months. The pain and stiffness are worst in the mornings, but symptoms improve with activity.

Examination shows painless nodules on the extensor surfaces of the arms and tenderness and swelling of the metacarpophalangeal and proximal interphalangeal joints.

Which of the following is involved in the pathologic process affecting her joints? A year-old woman and her year-old husband come to the physician for advice about their risk for having another child with Tay-Sachs disease.

Their 6-month-old son was recently diagnosed with this disease. There is a history of this disease in both the woman's and the man's families. Which of the following best represents the risk for this couple's next child to have Tay-Sachs disease? A year-old boy is brought to the physician because of painless swelling in his left breast for 1 month.

There is no family history of breast cancer. He is at the 65th percentile for height and 70th percentile for weight. Physical examination shows mild facial acne, thickeningof mustache hairon the face, and the presence of axillary hair. There is no adenopathy.

The left breast appears mildly enlarged with a palpable breast bud; the right breast is normal with nogynecomastia. Hisgenitalia are Tanner stage 3.

Which of the following is the most appropriate initial statement by the physician regarding this patient's breast finding? A "Have you tried smoking marijuana recently? That has been known to cause breast enlargement. Are you? We need to do some genetic testing. We'll have to do more tests to be sure. A year-old man comes to the physician because of cramping abdominal pain and diarrhea during the past 3 weeks; he has had a 4.

The pain is exacerbated following meals. He went on a camping trip in upstate New York 3 weeks ago, swimming in the nearby lakes and hiking in the mountains. His vital signs are normal. Which of the following diagnostic tests is most likely to identify the causal organism of this patient's condition? A Culture of the stool for enteric bacterial pathogens B Electron microscopy of the stool for small round viruses C Microscopic examination of the stool for ova and parasites D Polymerase chain reaction test of the stool for Shiga toxin E Proctoscopy and rectal biopsy.

A year-old African American girl is brought to the emergency department by her mother because of a6-hour history of fever and severe rib pain. She has had numerous episodes in the past. Her paternal aunt and uncle have had similar symptoms since youth.

The lungs are clear to auscultation. Abdominal examination shows tenderness to palpation. A peripheral blood smear is shown in the photomicrograph. Which of the following is the most likely underlying cause of this patient's symptoms? A Abnormal folding of the hemoglobin molecule caused by increased Pco2 B Abnormal hydrogen bonding in the hemoglobin caused by amino acid substitution on the a chain C Decreased oxygen affinity caused by an amino acid substitution in the hemoglobin a chain D Erythrocyte fragility caused by an amino acid substitution in glycoproteins on the cell surface E Polymerization of hemoglobin with hypoxic conditions due to amino acid substitution in the 3 chain.

A 5-year-old boy is brought to the physician by his mother because of a 3-month history of headache, clumsiness, and fatigue. He had a generalized tonic-clonic seizure 1 month ago. His mother says that he often falls while running.

Ophthalmologic examination shows ptosis of the left eye and bilateral external ophthalmoplegia. Physical examination shows weakness of the left lower extremity. Serum studies show an increased lactate concentration. Analysis of a calf muscle biopsy specimen obtained from the left lower extremity shows ragged red fibers.

Which of the following metabolic processes is most likely impaired in this patient? A Fatty acid oxidation. A year-old woman comes to the emergency department because of a 3-hour history of nausea and acute, sharp, right-sided lower abdominal pain that radiates to her back. She says the pain started 30 minutes into her aerobics class and has increased in severity since then.

Physical examination shows an enlarged right ovary. The result of a urine pregnancy test is negative. Ultrasonography of the pelvis confirms the presence of an enlarged ovary, and Doppler ultrasonography shows decreased adnexal flow.

Which of the following structures is most likely affected in this patient? A year-old man comes to the physician because of skin blistering for 1 week. Six months ago, he had blisters in his mouth that easily ruptured. Physical examination shows scattered blisters over the upper and lower extremities and trunk intermingled with crusted denuded areas. A biopsy specimen of an early lesion shows intraepidermal vesicle formation. Direct immunofluorescence microscopy of intact skin shows deposits of IgG on keratinocytes.

Which of the following structures is most likely involved in the skin disorder in this patient? A year-old man has cramping periumbilical pain.

After several hours, the pain shifts to the right lower quadrant and becomes constant. Which of the following mediators is most likely causing this patient's fever and leukocytosis?

A screening test is used to detect prostate cancer in a population of , men. The test is then used to screen a second population in which the prevalence of prostate cancer is different.

Which of the following is the most likely effect on the positive predictive value of this test? A Decreases as prevalence increases B Increases as prevalence decreases C Increases as prevalence increases D No change as prevalence changes. An investigator is studying the human immune response to tumor cell antigens in malignancies. Which of the following sets of cancer types and tumor antigens is most likely to produce the highest antibody titer? A previously healthy year-old man comes to the physician because of a 2-year history of gradually decreasing libido and intermittent inability to achieve erection or orgasm; he also has had decreased growth of facial hair during this period.

Puberty began at the age of 12 years. He takes no medications. He does not smoke or drink alcohol. His vital signs are within normal limits. Physical examination shows a typical male-pattern distribution of hair. Genital examination shows no abnormalities. Semen analysis shows a markedly decreased sperm count with impaired motility. An MRI of the brain shows a 1-cm lesion in the pituitary gland. Administration of which of the following is the most appropriate treatment for this patient?

Which of the following defects is most likely in this patient? A year-old woman with metastatic colon cancer has maintained remission by taking bevacizumab as a single agent. The ability to administer this agent despite it being a foreign protein is most likely a result of which of the following? A The agent being a humanized antibody B The agent containing the variable region of a murine antibody molecule directed against vascular endothelial growth factor.

A year-old man comes to the physician because of a low-grade fever, nasal congestion, and muscle aches for 1 week. He states that his girlfriend recently told him that his eyes appeared yellow. He has not had clay-colored stools or dark urine. His only medication is ibuprofen.

He has no recent history of foreign travel, tattoos, use of intravenous drugs, or exposure to blood products. Physical examination shows mild scleral icterus but no subungual icterus. The remainder of the examination shows no abnormalities. A year-old woman comes to the physician because of a 1-month history of progressive shortness of breath and anxiety. She says that her symptoms become much more pronounced as the day progresses. Breath sounds are normal on auscultation of the chest, but the patient has difficulty taking a long, deep breath.

Arterial blood gas analysis on room air shows: pH Pco2 Po2 7. Pulmonary function testing shows a decreased vital capacity, tidal volume, and expiratory reserve volume. Her residual volume is within the reference range. Which of the following is the most likely underlying cause of this patient's condition?

An year-old man has had temperatures to A latex agglutination test result for Epstein-Barr virus antibody is positive. Atypical cells with abundant lacey cytoplasm in the peripheral blood smear are most likely derived from which of the following types of cells?

An month-old boy is brought to the physician because of progressive facial abnormalities and slow growth during the past 6 months. He has an older brother with similar abnormalities who also has mental retardation.

The patient is below the 3rd percentile for length and at the 10th percentile for weight. Physical examination shows coarse facial features, hepatosplenomegaly, and joint stiffness. His urine concentrations of dermatan sulfate and heparan sulfate are increased.

A deficiency of which of the following enzyme activities is the most likely cause of the findings in this patient? A Galactosidase. A 6-year-old boy is brought to the physician by his mother because of a 2-day history of fever, sore throat, and occasional vomiting. His temperature is 39C Physical examination shows erythema and purulent exudate over the posterior pharyngeal wall and tonsils.

The anterior cervical glands are enlarged and tender. A throat culture grows group A Streptococcus. Because he is allergic to penicillin, treatment with erythromycin is begun. His condition improves during the next 2 days. The effectiveness of this antibiotic is most likely due to which of the following actions in protein synthesis? A male newborn at 34 weeks' gestation is delivered vaginally.

Physical examination shows no abnormalities except for a 1-cm, raised, red area on the anterior section of the neck. His mother is concerned, and the physician explains that the lesion is a hemangioma, a benign growth. This neoplasm most likely originated in which of the following tissues? A researcher in a pharmaceutical company designs a new protease inhibitor that inhibits replication of HIV in T lymphocytes in culture. In subsequent assays, which of the following findings is most likely to indicate that the compound is workingspecifically as a protease inhibitor?

A year-old man seeks medical attention because of the gradual onset of shortness of breath, night sweats, weight loss, and fatigue.

An x-ray of the chest shows enlargement of the hilar lymph nodes and nodular infiltrates in both lungs. A PPD skin test is negative. Examination of lung tissue obtained on biopsy shows multiple noncaseating granulomas with many giant cells. No organisms are seen on sections stained with hematoxylin and eosin, acid-fast stain, or silver stain. A year-old man dies 4 days after complete occlusion of the left coronary artery.

The left ventricle contains a large irregular area that is soft and pale. Which of the following processes is most likely responsible? A year-old woman comes to the physician because of a 3-week history of persistent cough that is worsened by the cold air in her drafty apartment. She does not smoke, takes no medications, and has no history of asthma or chronic pulmonary disease. Short-term cough suppressant treatment is initiated with a drug that does not cause constipation and has a low potential for substance abuse.

This drug is most likely which of the following? A year-old woman comes to the physician's office because of a She also complains of increased difficulties with concentration and memory for the past month. Determination of which of the following serum concentrations is most likely to confirm the diagnosis? A year-old woman is brought to the emergency department after being found lying on the sidewalk. She is conscious but says she is too weak to stand. Physical examination shows a red, swollen, tender tongue; angular stomatitis; and spoon-shaped nails.

Hemoglobin and mean corpuscular volume are decreased. A Vitamin B 12 cobalamin deficiency. A year-old man is brought to the emergency department because of a 6-hour history of chest pain and shortness of breath. A diagnosis of congestive heart failure is made. Diuretic therapy is initiated, and his symptoms resolve over the next 3 days. His physician believes that he should receive a pacemaker; however, the patient has expressed a desire to forego all invasive procedures.

The physician presents the benefits of the pacemaker fully, but he describes the risks and follow-up in a cursory manner. The patient consents to the procedure. This physician has violated which of the following ethical principles? A year-old man receives the diagnosis of squamous cell carcinoma of the esophagus. A barium swallow is shown. Esophagectomy at the region indicated by the arrows is most likely to involve ligation of arterial branches of which of the following vessels?

A year-old woman comes to the physician because of a 2-month history of a drooping left eyelid, intermittent pain of her left eye, and an unusually large pupil. Her husband has told her that the eye appears to be "looking sideways. An MRI of the brain shows an aneurysm of the left posterior communicating artery. The function of which of the following muscles is most likely to remain intact in this patient? A year-old woman is brought to the emergency department 6 hours after the onset of severe abdominal pain and confusion.

Her brother, father, and paternal grandmother had similar problems. Two weeks ago, she began a low-calorie diet. Physical examination shows restlessness, excess sweating, and tremors. There is no abdominal tenderness. Urine studies show an increased porphobilinogen concentration. Which of the following is the most likely pattern of inheritance causing this patient's condition? A year-old boy is brought to the physician by his mother because of a 2-month history of sneezing, coughing, and watery eyes immediately after he mows the lawn.

Fifteen minutes after his symptoms first begin, he develops a red rash containing areas that are soft to the touch. Physical examination shows boggy, soft, raised, pruritic, erythematous lesions with wheal and flare eruptions over the face, trunk, and back. Which of the following describes the most likely underlying mechanism of the rash in this patient? A year-old man who is a resident of a skilled nursing care facility is brought to the emergency department because of a 1-day history of temperatures to Several other residents have similar symptoms.

Treatment with a neuraminidase inhibitor is begun. This drug most likely will inhibit which of the following processes, therefore decreasing the duration of this patient's symptoms? A year-old man comes to the physician because of back pain and joint stiffness for 3 months. Hissymptoms improve aftermild exercise. During thisillness,he alsohas had fatigue and a 3. Physical examination and x-rays of the sacroiliac joints confirm a diagnosis of ankylosing spondylitis. Which of the followinglaboratory tests would be most appropriate for the patient's two children to evaluate their susceptibility to this disease?

A year-old woman comes to the physician because she wants to "do something about my wrinkles. Treatment with tretinoin is started. Collagen synthesis will most likely be increased in this patient by which of the following mechanisms? A C Activation of nuclear gene transcription Displaced vitamin A from cellular stores. A year-old man receives a bupivacaine injection for median nerve block as treatment of carpal tunnel syndrome. Which of the following is the mechanism of action of this drug on the membrane?

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