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usmle-11551

A popular news outlet recently published an article that discussed the size of low-density lipoprotein (LDL) cholesterol particles: type A and type B. Type B is thought to be more harmful to arterial walls. A group of researchers wants to determine whether patients who have an elevated level of type B LDL cholesterol are more likely to develop cardiovascular events. A study is designed with 3418 adult participants. Initial levels of type B LDL are obtained and participants are separated into normal and elevated levels of type B LDL. Socio-demographics including age, gender, education level, and smoking status are also recorded. The primary outcome is incidence of cardiovascular events over 10 years. Secondary outcomes include all-cause death, death by cardiovascular events, stroke, and hospitalizations. For this study, which of the following analyses would be the most appropriate measure to determine the association between type B LDL and cardiovascular events?

usmle-11552

A prospective cohort study was conducted to assess the relationship between LDL and the incidence of heart disease. The patients were selected at random. Results showed a 10-year relative risk of 2.3 for people with elevated LDL levels compared to individuals with normal LDL levels. The 95% confidence interval was 1.05-3.50. This study is most likely to have which of the following p values?

usmle-11553

A 27-year-old previously healthy man presents to the clinic complaining of bloody diarrhea and abdominal pain. Sexual history reveals that he has sex with men and women and uses protection most of the time. He is febrile with all other vital signs within normal limits. Physical exam demonstrates tenderness to palpation of the right upper quadrant. Subsequent ultrasound shows a uniform cyst in the liver. In addition to draining the potential abscess and sending it for culture, appropriate medical therapy would involve which of the following?

usmle-11554

A 31-year-old woman visits her primary care physician with the complaint that over the past 6 months she has “felt out of breath and dizzy while walking, even after short distances.” She reports no other medical problems and denies taking any medications, vitamins, supplements, recreational drugs, alcohol or tobacco. Her BMI is 24kg/m2. On physical examination, the patient has a loud second heart sound over the left upper sternal border, increased jugular venous pressure, and a palpable right ventricular impulse. Which of the following is the patient most at risk of developing if her condition is allowed to persist for a prolonged period:

usmle-11555

A 27-year-old G1P0 presents to her obstetrician for her normal 30-week obstetric appointment. She reports that she feels well and has no complaints. Her past medical history is notable for intermittent asthma. Her only medications are prenatal vitamins. She has gained 10 pounds, more than expected given her current stage of pregnancy. Abdominal ultrasound reveals the presence of twins with separate amniotic sacs that share a common chorion and placenta. During which time interval following fertilization did the morula divide into two in this mother?

usmle-11556

A 38-year-old woman presents to her primary care physician for evaluation of 3 months of increasing fatigue. She states that she feels normal in the morning, but that her fatigue gets worse throughout the day. Specifically, she says that her head drops when trying to perform overhead tasks. She also says that she experiences double vision when watching television or reading a book. On physical exam, there is right-sided ptosis after sustaining upward gaze for a 2 minutes. Which of the following treatments may be effective in treating this patient's diagnosis?

usmle-11557

A 34-year-old African American woman presents to clinic with complaints of bilateral eye pain and blurred vision that started about 1 week ago. She first noticed it following a snowboarding trip and self-treated with over-the-counter eye drops. However, the pain and vision changes progressively worsened. The patient has no significant past medical history. Review of systems was negative except for a persistent cough. Her chest radiography is shown in Figure A. What is the most likely cause of her ocular symptoms?

usmle-11558

A 24-year old G1P0 mother with no prenatal screening arrives to the hospital in labor and has an uneventful delivery. The infant is full term and has no significant findings on physical exam. Shortly after birth, an ophthalmic ointment is applied to the newborn in order to provide prophylaxis against infection. Which of the following is the most common mechanism of resistance to the ointment applied to this newborn?

usmle-11559

A 67-year-old male with a past medical history of diabetes type II, obesity, and hyperlipidemia presents to the general medical clinic with bilateral hearing loss. He also reports new onset vertigo and ataxia. The symptoms started a day after undergoing an uncomplicated cholecystectomy. If a drug given prophylactically just prior to surgery has caused this patient’s symptoms, what is the mechanism of action of the drug?

usmle-11560

A 64-year-old man presents to his primary care physician for a fall. The patient states that he has felt abnormally clumsy lately and has noticed himself tripping and bumping into things. He states he otherwise is healthy but admits to having unprotected sex with multiple people recently. His temperature is 99.5°F (37.5°C), blood pressure is 127/68 mm Hg, pulse is 100/min, respiratory rate is 24/min, and oxygen saturation is 98% on room air. Laboratory values are ordered as seen below. Hemoglobin: 9 g/dL Hematocrit: 30% Mean corpuscular volume: 110 fL Leukocyte count: 6,500/mm^3 with normal differential Platelet count: 197,000/mm^3 AST: 15 U/L ALT: 22 U/L GGT: 10 U/L Physical exam is notable for a broad-based and unstable gait. Which of the following conditions is the most likely etiology of this patient's presentation?

usmle-11561

A 33-year-old woman comes to the emergency department for severe abdominal pain for the past hour. The pain is 10/10, stabbing, and concentrated around the epigastric region with radiation to the back. She had 2 episodes of emesis and complains of nausea. She has had multiple similar episodes over the past 3 months which are not correlated with oral intake. She denies fever, weight changes, headaches, palpitations, bowel changes, or chest pain, but endorses nausea and stool that is hard to flush. Her medical history is significant for diabetes that is controlled with metformin. Her surgical history is significant for an elective cesarean section 5 years ago. She is currently sexually active with contraceptive use. What imaging finding would you expect in this patient?

usmle-11562

A 30-year-old man presents to your clinic complaining of excessive thirst and frequent urination for the past few months. Urine testing reveals a low urine osmolarity, which fails to increase after subjecting the patient to a water deprivation test and injection of desmopressin. Further into the encounter, the patient reveals that he has been on a mood stabilizer for bipolar disorder for several years. Which of the following is the most likely cause of his polyuria?

usmle-11563

A 29-year-old G2P2 female gives birth to a healthy baby boy at 39 weeks of gestation via vaginal delivery. Immediately after the delivery of the placenta, she experiences profuse vaginal hemorrhage. Her prior birthing history is notable for an emergency cesarean section during her first pregnancy. She did not receive any prenatal care during either pregnancy. Her past medical history is notable for obesity and diabetes mellitus, which is well controlled on metformin. Her temperature is 99.0°F (37.2°C), blood pressure is 95/50 mmHg, pulse is 125/min, and respirations are 22/min. On physical examination, the patient is in moderate distress. Her extremities are pale, cool, and clammy. Capillary refill is delayed. Which of the following is the most likely cause of this patient’s bleeding?

usmle-11564

A 35-year-old woman presents to a psychiatrist for an initial consultation. She reports that for the past 3 years, she has experienced several periods of depressed mood. The episodes do not coincide with any specific life events and seem to resolve after 4-6 weeks. During these episodes, she experiences a depressed mood, sleep disturbances, and a poor appetite, but she at times is able to enjoy spending time with her children and husband but other times she is distressed and cannot enjoy time with them. Upon further questioning, she also reports experiencing occasional episodes of elevated mood over the past ten years. During these episodes, she is very productive at her work as a lawyer and requires less sleep than usual. Her past medical history is notable for obesity, type I diabetes mellitus, and rheumatoid arthritis. She is on insulin and takes methotrexate. She smokes marijuana occasionally. Her temperature is 99.2°F (37.3°C), blood pressure is 124/80 mmHg, pulse is 78/min, and respirations are 17/min. On exam, she is quiet with a flattened affect, but is cooperative and answers questions thoroughly. Which of the following is the most likely diagnosis in this patient?

usmle-11565

An 8-year-old boy presents to his primary care pediatrician for routine check-up. During the visit, his mom says that she has noticed yellow bumps on his eyelids and was concerned about whether they were a problem. Upon hearing this concern, the physician inquires about parental health studies and learns that both parents have high cholesterol despite adhering to a statin regimen. Furthermore, other family members have suffered early myocardial infarctions in their 30s. Physical exam reveals flat yellow patches on the patient's eyelids bilaterally as well as hard yellow bumps around the patient's ankles. Based on clinical suspicion an LDL level is obtained and shows a level of 300 mg/dL. What protein is most likely defective in this patient causing these findings?

usmle-11566

A 42-year-old male with a history of schizophrenia presents to his psychiatrist for a normal follow-up visit. He is accompanied by his case manager. The patient was diagnosed with schizophrenia at the age of 27. After being trialed on two different medications, he was deemed to be stable on a third medication which he has been taking for the past 10 years. He reports that he occasionally hears voices. He lives in supportive housing, and his caretakers report that he prefers to be alone but is not disruptive. His temperature is 99°F (37.2°C), blood pressure is 130/90 mmHg, pulse is 105/min, and respirations are 18/min. On exam, he demonstrates a flattened affect and disorganized speech. A funduscopic examination reveals pigmented plaques at the retinal periphery. No deposits are seen in the cornea or anterior lens. This patient has most likely been treated with which of the following medications?

usmle-11567

A 62-year-old woman is hospitalized after a recent viral illness complicated by congestive heart failure. She has a past medical history of obesity and hypertension controlled on lisinopril but was otherwise healthy until she developed fatigue and edema after a recent viral illness. In the hospital, she is started on furosemide to manage her fluid status. On day 5 of her admission, the patient’s temperature is 100.0°F (37.8°C), blood pressure is 136/88 mmHg, pulse is 90/min, and respirations are 14/min. The patient continues to have normal heart sounds, but with crackles bilaterally on lung auscultation. Edema is 3+ up to the bilateral knees. On labs, her leukocyte count is now 13,000/mm^3, up from 9,000/mm^3 the day before. Differential shows that this includes 1,000 eosinophils/mm^3. Creatinine is 1.7 mg/dL from 1.0 mg/dL the day before. Which of the following is most likely expected on urinary analysis?

usmle-11568

A 46-year-old woman presents to your office with oral lesions as shown in Image A. On examination, you find that her back has flaccid bullae that spread when you apply lateral pressure with your fingertips. This patient most likely has autoantibodies directed against which of the following?

usmle-11569

A pharmaceutical company is studying the effect of a novel compound that they have discovered to treat osteoporosis. They perform a randomized controlled clinical trial to study if this compound has an effect on the incidence of hip fractures among osteoporotic patients. They find that there is no statistical difference between the experimental and control groups so they do not pursue the compound further. Two years later, a second team tests the same compound and finds that the compound is effective, and follow up studies confirm that the compound has a statistically significant effect on fracture risk. Which of the following most likely describes what occurred in the first study?

usmle-11570

A 28-year-old woman is brought to the hospital by her boyfriend. She has had three days of fever and headache followed by one day of worsening confusion and hallucinations. She also becomes agitated when offered water. Her temperature is 101°F (38.3°C). Two months prior to presentation, the couple was camping and encountered bats in their cabin. In addition to an injection shortly after exposure, what would have been the most effective treatment for this patient?

usmle-11571

A 42-year-old woman is admitted to the hospital for bacterial endocarditis and started on IV fluids and antibiotics. On hospital day 2, she develops severe back pain, accompanied by nausea and vomiting. Temperature is 99.8°F (37.7°C), blood pressure is 140/85 mmHg, pulse is 88/min, and respirations are 16/min. Physical exam reveals a systolic cardiac murmur and right-sided costovertebral angle tenderness. Urinalysis shows erythrocytes but no leukocytes, casts, or bacteria. CT scan with IV contrast is shown below (Figure A). What is the most likely cause of this patient's back pain?

usmle-11572

A 39-year-old woman presents to her gynecologist for her annual exam. She missed her "yearly exams" over the past 5 years because she was "too busy with work and family." She feels well and has no complaints. Her menses are regular, occurring every 29 days and lasting approximately 3 days. Menarche was at age 10. Her past medical history is notable for rheumatoid arthritis. She takes methotrexate. She has a 15-pack-year smoking history and drinks socially. She is married and has 2 children. She and her husband use condoms for protection. Her last Pap smear was 5 years ago and was normal. Her temperature is 98.8°F (37.1°C), blood pressure is 120/69 mmHg, pulse is 88/min, and respirations are 17/min. Pelvic examination demonstrates a normal appearing vagina with no adnexal or cervical motion tenderness. A Pap smear is performed, and a high-grade squamous intraepithelial lesion is identified. A cone biopsy is subsequently performed, and results are shown in Figure A. This patient most likely has which of the following conditions?

usmle-11573

A 66-year-old woman presents to her primary care provider with several days of left flank pain radiating to the abdomen and groin. The patient states that she has noticed a pink tinge to her urine as well. Of note, she has not had any fevers, but endorses several months of fatigue and constipation. The patient was previously healthy except for mild untreated hypertension. On exam, her temperature is 98.6°F (37.0°C), blood pressure is 130/84 mmHg, pulse is 76/min, and respirations are 12/min. On further workup, the patient is found to have calcium oxalate nephrolithiasis with hypercalciuria. Blood studies demonstrate increased parathyroid hormone (PTH) and hypercalcemia. Which of the following is the most likely cause?

usmle-11574

A 16-year-old girl is brought to the clinic by her mother for amenorrhea. The patient has never had a menstrual cycle and is worried as all her friends “have started to go through puberty.” She has been otherwise healthy with an uncomplicated birth history. “I told her not to worry since I also got my period late,” her mother reported during the encounter. Physical examination demonstrates Tanner stage 2 breasts, genital, and pubic hair. Temperature is 98.7 °F (37.1°C), blood pressure is 156/100mmHg, pulse is 92/min, and respirations are 12/min. What laboratory abnormalities would you expect to find in this patient?

usmle-11575

A 10-year-old girl is brought to the neurologist for management of recently diagnosed seizures. Based on her clinical presentation, the neurologist decides to start a medication that works by blocking thalamic T-type calcium channels. Her parents are cautioned that the medication has a number of side effects including itching, headache, and GI distress. Specifically, they are warned to stop the medication immediately and seek medical attention if they notice skin bullae or sloughing. Which of the following conditions is most likely being treated in this patient?

usmle-11576

A 75-year-old African American female with a history of uncontrolled diabetes and severe asthma presents to the emergency room after one week of facial edema, tenderness on the maxillary sinuses when palpated, and left-sided ecchymoses. About two days ago, she started to notice her left side of her face started to droop. She believes this may be related to the high doses of steroids that she had been taking for that past three weeks. A head CT was performed demonstrating opacification of the left ethmoid sinus and a tissue sample was sent (Figure A). Which of the following if given promptly, along with surgical debridement, may save this patient's life?

usmle-11577

A 10-year-old boy is brought to the pediatrician by his father because of recent changes in his behavior. His father states that he has noticed that the boy has begun to appear less coordinated than normal and has had frequent falls. On exam, the pediatrician observes pes cavus and hammer toes. The pediatrician makes a presumptive diagnosis based on these findings and recommends a formal echocardiogram. The pediatrician is most likely concerned about which of the following cardiovascular defects?

usmle-11578

A 9-year-old African-American boy presents to his primary care physician in order to be evaluated for fatigue and shortness of breath. He lives in an old house with his parents and eats a diet consisting of mostly fast food and soda. A few days prior to presentation he ate fava beans. His mom has noticed that he is tired particularly in the morning. Physical exam reveals a thin, pale boy with decreased color under his eyelids. A panel of hematologic tests is obtained with the following results: Hemoglobin: 12 g/dL Leukocyte count: 5,250/mm^3 Platelet count: 172,000/mm^3 Mean corpuscular volume: 95 µm^3 Direct bilirubin: Normal Indirect bilirubin: Increased A blood smear is obtained and shown in Figure A demonstrating internal crystals of Hemoglobin C in red blood cells. Which of the changes are associated with the most likely cause of this patient's condition?

usmle-11579

A 33-year-old woman with no prior medical history is brought to the emergency department for severe bilateral lower extremity pain, which began just after completing a marathon. She also reports fatigue and brown urine. On exam, motor strength is 3/5 throughout the left lower extremity, 4/5 throughout the right lower extremity, and 5/5 in both upper extremities. The lower extremities are tender to palpation bilaterally but non-edematous and non-erythematous. Echocardiogram (ECG) is shown below (Figure A). Which of the following abnormalities is most likely to be seen in this patient?

usmle-11580

A 65-year-old man presents to his primary care provider after noticing increasing fatigue over the past several weeks. He now becomes short of breath after going up 1 flight of stairs. He was previously healthy and has not seen a doctor for several years. He denies any fever or changes to his bowel movements. On exam, his temperature is 98.8°F (37.1°C), blood pressure is 116/76 mmHg, pulse is 74/min, and respirations are 14/min. On basic labs, his hemoglobin is found to be 9.6 g/dL and MCV is 75 fL. Fecal blood testing is positive for occult blood. Imaging is notable for a mass in the cecum that is partially obstructing the lumen, as well as several small lesions in the liver. Which of the following structures is most at risk for involvement in this patient’s disease?

usmle-11581

A 19-year-old woman presents to an outpatient psychiatrist after 2 weeks of feeling “miserable.” She has been keeping to herself during this time with no desire to socialize with her friends or unable to enjoy her usual hobbies. She also endorses low energy, difficulty concentrating and falling asleep, and decreased appetite. You diagnose a major depressive episode but want to screen for bipolar disorder before starting her on an anti-depressant. Which of the following cluster of symptoms, if previously experienced by this patient, would be most consistent with bipolar I disorder?

usmle-11582

A 75-year-old gentleman is brought to the ED with confusion that started earlier this morning. His family notes that he was complaining of feeling weak last night and also had a slight tremor at the time. He is afebrile and he has no known chronic medical conditions. Physical exam reveals a cooperative but confused gentleman. His mucous membranes are moist, he has no focal neurological deficits, and his skin turgor is within normal limits. His lab results are notable for: Serum Na+: 123 mEq/L Plasma osmolality: 268 mOsm/kg Urine osmolality: 349 mOsm/kg Urine Na+: 47 mEq/L Which of the following malignancies is most likely to be responsible for this patient's presentation?

usmle-11583

A 75-year-old male presents to the emergency room complaining of severe lower abdominal pain and an inability to urinate. He reports that he last urinated approximately nine hours ago. When asked to urinate, only a few drops dribble from the tip of his penis. Further questioning reveals that the patient has experienced progressively worsening difficulty with urinating over the past two years. He has lived alone for five years since his wife passed away. He has not seen a doctor in that time. His temperature is 98.8°F (37.1°C), blood pressure is 145/90 mmHg, pulse is 115/min, and respirations are 22/min. He appears to be in severe pain. Physical examination reveals a distended bladder and significant tenderness to palpation over the inferior aspect of his abdomen. Which of the following sets of lab values would most likely be found in a urinalysis of this patient?

usmle-11584

A 3-year-old boy is brought in by his parents for placement of a tracheostomy tube in order to allow for better ventilator support of his breathing. At birth, he was flaccid with a poor sucking reflex. Since then, his weakness has progressively worsened such that he is unable to sit, eat, or breathe independently. Family history reveals that his grandfather was affected by a degenerative disorder at age 50, and his father had the same degenerative disorder at age 30. Examination is significant for tongue fasciculations and absent deep tendon reflexes. Which of the following forms of inheritance is associated with the most likely cause of this patient's disorder?

usmle-11585

A 17-year-old boy is brought to the emergency department by his parents 6 hours after he suddenly began to experience dyspnea and pleuritic chest pain at home. He has a remote history of asthma in childhood but has not required any treatment since the age of four. His temperature is 98.4°F (36.9°C), blood pressure is 100/76 mmHg, pulse is 125/min, respirations are 24/min. On exam, he has decreased lung sounds and hyperresonance in the left upper lung field. A chest radiograph shows a slight tracheal shift to the right. What is the best next step in management?

usmle-11586

A 41-year-old man presents to the emergency department with a 1-month history of increased difficulty when swallowing solids. He also says that he has been experiencing weight loss and muscle spasms. He has no significant past medical history but his family has several members that had rare tumors such as pheochromocytomas. On physical exam, he is found to have an enlarged thyroid gland and a biopsy is obtained from this mass. Histology of the removed section was stained and the result is shown in Figure A. The cells from which this mass is derived normally produce a substance with which of the following functions?

usmle-11587

A 52-year-old man who was recently hospitalized with a pulmonary embolism is put on an unfractionated heparin drip as a bridge to chronic warfarin therapy. During morning rounds, he is found to have diffuse bruising despite minimal trauma, and his heparin infusion rate is found to be faster than prescribed. A coagulation panel is obtained, which shows a aPTT of 130 seconds (therapeutic 70-120 seconds), and the decision is made to reverse the effects of heparin. Which of the following would most likely be administered in order to do this?

usmle-11588

A 50-year-old woman presents to the ED 6 hours after ingesting three bottles of baby aspirin. He complains of nausea, vomiting, dizziness, and tinnitus. His blood pressure is 135/80 mmHg, pulse is 110/min, respirations are 32/min, temperature is 100.1 deg F (37.8 deg C), and oxygen saturation is 99% on room air. Arterial blood gas at room air shows, PCO2 11 mmHg, and PO2 129 mmHg. Blood salicylate level is 55 mg/dL. Management should involve which of the following acid-base principles?

usmle-11589

A 58-year-old man presents to the emergency department following a motor vehicle accident where he was an unrestrained passenger. On initial presentation in the field, he had diffuse abdominal tenderness and his blood pressure is 70/50 mmHg and pulse is 129/min. Following administration of 2 L of normal saline, his blood pressure is 74/58 mmHg. He undergoes emergency laparotomy and the source of the bleeding is controlled. On the second post-operative day, his blood pressure is 110/71 mmHg and pulse is 90/min. There is a midline abdominal scar with no erythema and mild tenderness. Cardiopulmonary examination is unremarkable. He has had 300 mL of urine output over the last 24 hours. Urinalysis shows 12-15 RBC/hpf, 2-5 WBC/hpf, and trace protein. What additional finding would you expect to see on urinalysis?

usmle-11590

A 12-year-old boy presents to the emergency department after falling from his bike. He is holding his right arm tenderly and complains of pain in his right wrist. When asked, he says that he fell after his front tire hit a rock and landed hard on his right hand. Upon physical examination he is found to have tenderness on the dorsal aspect of his wrist in between the extensor pollicis longus and the extensor pollicis brevis. Given this presentation, which of the following is the most likely bone to have been fractured?

usmle-11591

A 9-year-old girl is being evaluated for suspected Bartter’s syndrome, a renal disorder caused by defective Cl- reabsorption by the Na+/K+/2Cl- cotransporter. In normal individuals, the segment of the nephron that houses this transporter is also characterized by which of the following?

usmle-11592

A 3-year-old boy is brought for general developmental evaluation. According to his parents he is playing alongside other children but not in a cooperative manner. He has also recently begun to ride a tricycle. Upon questioning you also find that he is toilet trained and can stack 9 blocks. Upon examination you find that he can copy a circle though he cannot yet copy a triangle or draw stick figures. In addition he is currently speaking in two word phrases but cannot yet use simple sentences. Based on these findings you tell the parents that their child's development is consistent with which of the following?

usmle-11593

A 28-year-old female lawyer noticed the development of a papulopustular rash near her hip region (Figure A) several days after treating herself to a day at the spa. Which of the following is NOT a characteristic of the organism causing the rash?

usmle-11594

A 35-year-old male presents to his primary care physician complaining of intermittent chest pain. He reports that he has started to experience dull chest pain whenever he walks a half mile or more. The pain radiates to his left shoulder and jaw. He has previously been healthy and takes no medications. His father passed away from a myocardial infarction at the age of 45. He does not smoke and drinks alcohol occasionally. A notable physical examination finding is shown in Figure A. Which of the following is most likely affected in this patient?

usmle-11595

A 61-year-old female with a history of breast cancer currently on chemotherapy is brought by her husband to her oncologist for evaluation of a tremor. She reports that she developed a hand tremor approximately six months ago, prior to the start of her chemotherapy. The tremor is worse at rest and decreases with purposeful movement. She has experienced significant nausea and diarrhea since the start of her chemotherapy. Her past medical history is also notable for diabetes and hypertension treated with metformin and lisinopril, respectively. She takes no other medications. On examination, there is a tremor in the patient’s left hand. Muscle tone is increased in the upper extremities. Gait examination reveals difficulty initiating gait and shortened steps. Which of the following medications is contraindicated in the management of this patient’s nausea and diarrhea?

usmle-11596

A 31-year-old G3P1 woman who is at 37 weeks of gestation is brought into the emergency department by her husband after repeated twitching. According to the husband, they were watching TV when she suddenly became unresponsive and her hands and legs started shaking. The episode lasted about 5 minutes and she “seemed to be sleeping afterwards.” Her past medical history is significant for pregnancy induced hypertension. The patient is tired but responsive and denies urinary incontinence, paresthesia, fever, upper respiratory signs, or new medication changes. She denies a history of seizures. Her temperature is 99°F (37°C), blood pressure is 186/97 mmHg, pulse is 96/min, and respirations are 12/min. Physical examination demonstrates a lethargic patient with moderate right upper quadrant tenderness. What is the most appropriate next step for this patient?

usmle-11597

A 71-year-old man presents to his cardiologist with a 1-month history of increasing shortness of breath. He says that he is finding it very difficult to walk up the flight of stairs to his bedroom and he is no longer able to sleep flat on his bed because he wakes up choking for breath. His past medical history is significant for a myocardial infarction 3 years ago. On physical exam, he is found to have diffuse, moist crackles bilaterally on pulmonary auscultation and pitting edema in his lower extremities. Serum tests reveal an increased abundance of a product produced by cardiac myocytes. Which of the following most likely describes the function of this product?

usmle-11598

A 43-year-old male visits the emergency room around 4 weeks after getting bitten by a bat during a cave diving trip. After cleansing the wound with water, the patient reports that he felt well enough not to seek medical attention immediately following his trip. He does endorse feeling feverish in the past week but a new onset of photophobia and irritability led him to seek help today. What would the post-mortem pathology report show if the patient succumbs to this infection?

usmle-11599

A 2-year-old boy is brought to the pediatrician for recurrent nosebleeds. The boy was adopted two months ago and the parents have no record of his medical or family history. They report that the child has had frequent prolonged nosebleeds several times per week. Despite them applying pressure on the distal aspect of the nares and keeping his head elevated, the bleeding generally continues for hours. On exam, the boy appears pale and lethargic. A blood sample is obtained but the child bleeds through multiple pieces of gauze. No agglutination is observed when ristocetin is added to the patient’s blood. The addition of normal plasma to the sample still does not lead to agglutination. This patient has a condition that is most consistent with which of the following modes of transmission?

usmle-11600

A 30-year-old G1P0 woman at 26 weeks gestation presents to the obstetric emergency room for an evaluation after being involved in a motor vehicle accident. She was in the passenger seat of her car when the car was hit on the side by a drunk driver. She is currently in no acute distress but is worried about her pregnancy. The patient attended all her prenatal visits and took all her appropriate prenatal vitamins. Her past medical history is notable for diabetes mellitus, for which she takes metformin. Her temperature is 98.6°F (37°C), blood pressure is 135/75 mmHg, pulse is 109/min, and respirations are 22/min. A non-stress test is non-responsive, and a biophysical profile demonstrates abnormal fetal breathing, fetal activity, and fetal muscle tone. An amniotic fluid sample is taken which demonstrates a lecithin/sphingomyelin ratio of 1.9. Which of the following is the next best step in the management of this patient?

usmle-11601

A 43-year-old female with a history of polycystic kidney disease status post kidney transplant presents to her nephrologist for a normal follow-up visit. Her operation was 6 months ago. She was started on multiple medications prior to the transplant. Her medical history is otherwise notable for hypertension, asthma, and rheumatoid arthritis. She currently reports that she has noticed excess hair growth since the operation. A unique physical examination finding is also shown in Figure A. The medication that is most likely responsible for this patient’s current symptoms has which of the following mechanisms of action?

usmle-11602

A 13-year-old male presents to his pediatrician complaining of headaches and difficulty with his vision. Physical exam reveals weight in the 50th percentile but height in the 25th percentile. Previously, he had consistently measured in the 50th percentile for both height and weight. Vital signs are within normal limits. Visual testing reveals 20/30 vision with temporal field defects on both the left and the right. Head CT reveals the lesion seen in Figure A. A biopsy is performed (Figure B). The lesion is derived from the remnants of a pouch that is the embryonic precursor to which structure in the brain?

usmle-11603

A 4-year-old boy is brought to his pediatrician by his mother for a cough. His mother reports that he has had a loud cough and hoarse voice for the past 3 days. He also had a runny nose and mild fever last week. He was born with Tetralogy of Fallot and underwent surgery as an infant. He has been followed regularly by a pediatric cardiologist. There are no other sick contacts in the household. His temperature is 100.9°F (38.3°C), blood pressure is 105/65 mmHg, pulse is 110/min, and respirations are 24/min. An anteroposterior radiograph of the neck is shown in Figure A. A lung radiograph is normal. Which of the following pathogens is the most likely cause of this patient's condition?

usmle-11604

A 72-year-old female is brought to the emergency department by ambulance because she was unable to walk. She says that she cut her leg while falling about a week ago. Since then, the wound has started draining fluid and become progressively more painful. She is found to have necrotizing fasciitis and is taken emergently to the operating room. Histological examination of cells along the fascial planes reveal cells undergoing necrosis. Which of the following represents the earliest sign that a cell has progressed to irreversible damage in this patient?

usmle-11605

A 38-year-old, working, first-time mother brings her 9-month-old male infant to the pediatrician for "wounds that simply won't heal" and bleeding gums. She exclaims, "I have been extra careful with him making sure to not let him get dirty, I boil his baby formula for 15 minutes each morning before I leave for work to give to the caregiver, and he has gotten all of his vaccinations." This infant is deficient in a molecule that is also an essential co-factor for which of the following reactions?

usmle-11606

A parent-teacher conference is called to discuss the behavior of a 9-year-old boy. According to the boy's teacher, he has become progressively more disruptive during class. He is performing poorly in school and has trouble focusing. He is destructive to classroom property, tore a classmate's art project, and takes other children's lunches regularly. He is avoided by his classmates. His mother reports that her son can "sometimes be difficult." Recently he placed a rubber band around the cats tail, resulting in gangrene. What is the most likely diagnosis?

usmle-11607

A 64-year-old woman presents to an endocrinologist after her second time having a kidney stone in the last year. The patient reports no other symptoms except overall fatigue. On evaluation, the patient’s temperature is 98.4°F (36.9°C), blood pressure is 120/76 mmHg, pulse is 72/min, and respirations are 12/min. The patient has no neck masses and no tenderness to palpation in the abdomen. On laboratory workup, the endocrinologist finds that the patient has elevated parathyroid hormone levels and serum calcium. For surgical planning, the patient undergoes a sestamibi scan, which localizes disease to an area near the superior aspect of the thyroid in the right neck. Which of the following is the embryologic origin of this tissue?

usmle-11608

A 4-year-old-female presents with a flattened, reddish 2 cm lump located at the base of the tongue. The patient's mother reports her having trouble swallowing, often leading to feeding difficulties. The mother also reports lethargy, constipation, dry skin, and hypothermia. Which of the following is the most appropriate management of this patient’s presentation?

usmle-11609

A 44-year-old obese woman presents with abdominal pain. She says the pain started while she was having lunch at a fast-food restaurant with her children. The pain began shortly after eating and has persisted for 6 hours. She has vomited once. Her vital signs are as follows: HR 88, BP 110/70 mmHg, T 38.5°C (101.3°F). On physical exam, she is tender to palpation in the right upper quadrant of her abdomen. Her skin appears normal. Her liver function tests, amylase, and lipase levels are normal. A right upper quadrant abdominal ultrasound is challenged by her body habitus and is not able to visualize any gallstones. Which of the following is the most likely cause of her presentation?

usmle-11610

A 29-year-old Mediterranean man presents to the clinic for fatigue and lightheadedness for the past week. He reports an inability to exercise as his heart would beat extremely fast. He was recently diagnosed with active tuberculosis and started on treatment 2 weeks ago. He denies fever, weight loss, vision changes, chest pain, dyspnea, or bloody/dark stools. A physical examination is unremarkable. A peripheral blood smear is shown in figure A. What is the most likely explanation for this patient’s symptoms?

usmle-11611

While in the ICU, a 62-year-old male undergoes placement of a Swan-Ganz catheter to evaluate his right heart pressures. All pressures are found to be within normal limits, and the cardiology fellow records a pulmonary wedge pressure of 10 mmHg. Which of the following are normal values for the pressures that will be obtained from this patient's right ventricle?

usmle-11612

A 34-year-old man presents to his physician with a complaint of lower back pain and stiffness for the past few months. He describes the pain as being worse in the morning and then gradually improving with activity throughout the day. On physical exam, he has decreased anterior flexion of the lumbar spine. A radiograph of his lumbar spine is obtained and is shown in Figure A. What is the patient’s most likely diagnosis?

usmle-11613

A 31-year-old G3P2 woman presents to labor and delivery triage because she has had bleeding over the last day. She is currently 5 months into her pregnancy and has had no concerns prior to this visit. She previously had a delivery through cesarean section and has otherwise had uncomplicated pregnancies. She denies fever, pain, and discomfort. On presentation, her temperature is 99.1°F (37.3°C), blood pressure is 110/70 mmHg, pulse is 81/min, and respirations are 15/min. Physical exam reveals an alert woman with slow, painless, vaginal bleeding. Which of the following risk factors are associated with the most likely cause of this patient's symptoms?

usmle-11614

A 17-year-old girl makes an appointment with her pediatrician because she is concerned that she may have gotten a sexually transmitted infection. Specifically, she had unprotected sex two weeks ago and has since been experiencing painful urination and abdominal pain. Laboratory tests confirm a diagnosis of Chlamydial infection. At this point, the girl says that she wants to personally give permission to be treated rather than seek consent from her parents because they do not know that she is in a relationship. She also asks that the diagnosis not be reported to anyone. What should the physician do with regards to these two patient requests?

usmle-11615

A 48-year-old homeless man presents to a free clinic complaining of several weeks of bleeding gums. He states that he has not seen dental or medical care for several years and that the bleeding has been painless. He normally sleeps on the street or occasionally stays at a shelter and typically eats 1-2 fast food meals per day. On exam, his temperature is 98.4°F (36.9°C), blood pressure is 122/76 mmHg, pulse is 64/min, and respirations are 12/min. He has poor dentition and significant periodontal disease with notable areas of bleeding gingiva. The patient is found to have coarse hair and on further questioning, the patient endorses the recent loss of 2 of his teeth and several weeks of fatigue. Which of the following processes is most immediately affected by his condition?

usmle-11616

A 12-year-old boy is brought to the emergency department by his mother because he has been having difficulty breathing. He started having symptoms about 3 days ago when he started experiencing persistent coughing, runny nose, and a low grade fever. Since then he has been experiencing dyspnea that grew worse until he felt that he could no longer breathe. His mom says that this has happened many times before. On presentation, physical exam reveals an anxious, thin boy who is using his accessory muscles to breathe. Prolonged expiratory wheezes are heard on auscultation of his lungs bilaterally. During stabilization, he is prescribed a drug for treatment of his condition. The patient's mother recognizes the drug since her father, a 40-pack-year smoker, also takes the medication and she is told that the drug is able to beneficially inhibit a receptor on smooth muscle in both cases. Which of the following drugs most likely has a similar mechanism of action as the drug prescribed to this patient?

usmle-11617

A 24-year-old woman comes to the clinic complaining of headache and sinus drainage for the past 13 days. She reports cold-like symptoms 2 weeks ago that progressively got worse. The patient endorses subjective fever, congestion, sinus headache, cough, and chills. She claims that this is her 5th episode within the past year and is concerned if “there’s something else going on.” Her medical history is significant for asthma that is adequately controlled with her albuterol inhaler. Her laboratory findings are shown below: Serum: Hemoglobin: 16.2 g/dL Hematocrit: 39 % Leukocyte count: 7,890/mm^3 with normal differential Platelet count: 200,000/mm^3 IgA: 54 mg/dL (Normal: 76-390 mg/dL) IgE: 0 IU/mL (Normal: 0-380 IU/mL) IgG: 470 mg/dL (Normal: 650-1500 mg/dL) IgM: 29 mg/dL (Normal: 40-345 mg/dL) What is the most likely diagnosis?

usmle-11618

A 67-year-old male presents to his primary care physician complaining of increased fatigue over the last year. He also says that his friends say he appears to be more pale. His past medical history is significant for 10 years of arthritis. Physical exam reveals spoon shaped nails as well as conjunctival pallor. Based on clinical suspicion RBC tests are ordered showing an mean corpuscular volume (MCV) of 75 fl (normal 80-100 fl) and a peripheral blood smear is obtained and found to be normal. Iron studies shows a serum iron of 30 micromolar (normal range 50-170) and a serum ferritin of 300 micrograms/liter (normal range 15-200). What is the most likely diagnosis in this patient?

usmle-11619

An 80-year-old African American male presents complaining of worsening shortness of breath that occurs during his weekly round of golf. He also notes he has been waking up at night "choking and gasping for air", though he has been able to gain some relief by propping his head on a stack of pillows before he goes to bed. Upon auscultation, a low frequency, early diastolic gallop is heard over the apex while the patient rests in the left lateral decubitus position. This finding is most consistent with which of the following?

usmle-11620

A 55-year-old obese woman is referred to the cardiology clinic for progressive dyspnea. She has had no recent travel or sick contacts. Besides a multivitamin, she has only tried online weight-loss medications for the past five years, including fenfluramine-phentermine. An echocardiogram reveals a dilated right ventricle with systolic pressure of 60 mmHg as well as both tricuspid and pulmonary regurgitation. A right heart catheterization shows a mean pulmonary artery pressure of 40 mmHg. What disease process is most analogous to this patient's presentation?

usmle-11621

A 42-year-old man presents to a neurologist for evaluation of severe headache. He started experiencing episodic headaches and palpitations 3 months ago; however, he thought that these symptoms were simply related to the stress of moving and starting a new job. He has continued to experience these intermittent headaches and has also noticed that he sweats profusely during these episodes. On presentation his temperature is 99.1°F (37.3°C), blood pressure is 163/112 mmHg, pulse is 112/min, and respirations are 15/min. Physical exam reveals pallor and perspiration but is otherwise unremarkable. The most likely cause of this patient's symptoms is produced by cells located in which region of the histology slide shown in figure A?

usmle-11622

A 61-year-old male presents to the emergency room with difficulty breathing. He has had a dry cough and shortness of breath for the last 6 days. This morning, his cough acutely worsened prompting him to seek care. His temperature is 99.0°F (37.2°C), blood pressure is 140/85 mmHg, pulse is 110/min, respirations are 27/min, and pulse oximetry is 88% on room air. There are decreased breath sounds at the right lung base. Chest radiograph is shown in Figure A. You perform a thoracentesis and pleural fluid findings are shown below: Appearance: Clear Lactate dehydrogenase: 40 U/L Specific gravity: 1.01 Leukocyte count: 200/mm^3 Erythrocyte count: Trace Gram stain: Negative Which of the following is the most likely underlying etiology for this patient’s respiratory distress?

usmle-11623

A 47-year-old woman presents to a local medical shelter while on a mission trip with her church to help rebuild homes after a hurricane. She has been experiencing severe nausea, vomiting, and diarrhea for the last 2 days and was feeling too fatigued to walk this morning. On presentation, her temperature is 99.2°F (37.3°C), blood pressure is 95/62 mmHg, pulse is 121/min, and respirations are 17/min. Physical exam reveals decreased skin turgor, and a stool sample reveals off-white watery stools. Gram stain reveals a gram-negative, comma-shaped organism that produces a toxin. Which of the following is consistent with the action of the toxin most likely involved in the development of this patient's symptoms?

usmle-11624

A 2-year-old boy is brought to his pediatrician by his parents for a routine visit. Since his 18-month visit, the parents have become concerned that his speech does not seem to be developing appropriately. The parents report that the patient’s vocabulary is still limited to fewer than 10 words, and he is still only using single words to describe things. The parents say that his motor milestones do not seem to be affected, as the patient is very physically active and can run and kick a ball. At times the patient seems hyperactive and can be difficult to redirect. On exam, his temperature is 98.4°F (36.9°C), blood pressure is 110/70 mmHg, pulse is 80/min, and respirations are 14/min. The rest of the exam is unremarkable, except that the patient’s face appears to be abnormally long and narrow. The patient is further referred to a geneticist, as he is believed to have a trinucleotide repeat disorder. Which of the following is the most likely inheritance pattern of this disorder?

usmle-11625

A 78-year-old woman is accompanied by her family for a routine visit to her primary care provider. The family states that 5 months prior, the patient had a stroke and is currently undergoing physical therapy. Today, her temperature is 98.2°F (36.8°C), blood pressure is 112/72 mmHg, pulse is 64/min, and respirations are 12/min. On exam, she is alert and oriented with no deficits in speech. Additionally, her strength and sensation are symmetric and preserved bilaterally. However, on further neurologic testing, she appears to have some difficulty with balance and a propensity to fall to her right side. Which of the following deficits does the patient also likely have?

usmle-11626

A 3-year-old boy is accompanied by his mother to his pediatrician for an annual physical. His mother says that he has recently begun daycare, and has been playing well with the other children. However, a few weeks ago he developed a rash that “looks a lot like acne” on his knees and elbows (Figure A). His mother additionally reports that he is noticeably smaller than the other children at his daycare. Temperature is 99.0°F (37.2°C), blood pressure is 102/73 mmHg, pulse is 95/min and regular, and respirations are 20/min. Physical exam reveals a thin boy with a scaphoid abdomen. His height is less than the 3rd percentile for his age. Mild genu varum is present, along with the findings in Figure B. Which of the following best explains the etiology of this patient’s condition?

usmle-11627

A 12-year-old boy presents to your office with facial swelling and dark urine. He has no other complaints other than a sore throat 3 weeks ago that resolved after 6 days. He is otherwise healthy, lives at home with his mother and 2 cats, has no recent history of travel ,and no sick contacts. On physical examination his temperature is 99°F (37.2°C), blood pressure is 130/85 mmHg, pulse is 80/min, respirations are 19/min, and pulse oximetry is 99% on room air. Cardiopulmonary and abdominal examinations are unremarkable. There is mild periorbital and pedal edema. Urinalysis shows 12-15 RBC/hpf, 2-5 WBC/hpf, and 30 mg/dL protein. Which additional finding would you expect to see on urinalysis?

usmle-11628

A 16-year-old boy is brought to the emergency department by ambulance with a visible deformity of the upper thigh after being involved in a motor vehicle collision. He is informed that he will require surgery and is asked about his medical history. He mentions that he had surgery to remove his tonsils several years ago and at that time suffered a complication during the surgery. Specifically, shortly after the surgery began, he began to experience severe muscle contractions and an increased body temperature. Based on this information, a different class of muscle relaxants are chosen for use during the upcoming surgery. If these agents needed to be reversed, the reversal agent should be administered with which of the following to prevent off-target effects?

usmle-11629

A 64-year-old male presents to the emergency room complaining of chest pain. He reports a pressure-like sensation over his sternum that radiates into his jaw. The pain came on suddenly 2 hours ago and has been constant since then. His past medical history is notable for a stable abdominal aortic aneurysm, hypertension, diabetes, and hyperlipidemia. He takes aspirin, enalapril, spironolactone, atorvastatin, canagliflozin, and metformin. His temperature is 99.1°F (37.3°C), blood pressure is 155/85 mmHg, pulse is 115/min, and respirations are 22/min. On exam, he is diaphoretic and in moderate distress. He is admitted for further management and does well after initial stabilization. He is seen two days later by the admitting team. This patient is at increased risk for a complication that is characterized by which of the following?

usmle-11630

A 3-year-old male is brought to the emergency room by his mother for a rash and fever. The mother reports that the child first developed a cough and malaise three days ago. Over the last 24 hours, a rash developed and the patient had a temperature up to 101.4°F (38.6°C) the night prior to presentation. The child’s medical history is notable for a prior hospitalization at the age of 2 for fever, vomiting, and lethargy. During that hospitalization, a cerebrospinal fluid sample demonstrated gram-negative diplococci. His current temperature is 100.9°F (38.3°C), blood pressure is 130/85 mmHg, pulse is 115/min, and respirations are 22/min. Physical examination reveals a lethargic male child with a diffuse petechial skin rash that is most prominent on the trunk and legs. This patient most likely has a deficiency in which of the following factors?

usmle-11631

A 9-year-old male is brought to the pediatrician by his mother because of several days of fever and chills. In addition, his mom notes that he has complained about muscle aches and joint pain. He recently returned from a boy scout trip where he went swimming, hiking, and camping. He has otherwise been healthy and has no past medical history. His mother also notes that one of his siblings was recently ill with an upper respiratory tract infection. Physical exam reveals an agitated, ill-appearing boy with the rash shown in Figure A. Based on clinical suspicion, the boy is started on a course of antibiotics. Which of the following describes the mechanism of action for the antibiotic most likely administered in this case?

usmle-11632

The parents of a 4-year-old present to the pediatrician because they are concerned about the poor growth and odd behavior of their son. Their son has been at the 10th percentile for growth since birth and they have noticed that his skin seems to have a bluish hue to it whenever he cries or is agitated. Recently, they have noticed that when he squats it seems to relieve these symptoms. What was the embryologic cause of this patient's current symptoms?

usmle-11633

A 22-year-old man presents to a psychiatrist complaining of mood fluctuations. He is accompanied by his mother who reports that the patient recently experienced a 5-day episode of minimal sleep and unusual levels of energy. The patient admits to spending $2,000 of his parent’s money, without asking, on a down payment for a motorcycle. The episode resolved after 5 days, at which point the patient felt guilty and upset. The patient’s medical history is notable for multiple month-long episodes in the past 2 years of feeling sad, sleeping more than usual, being uninterested in his hobbies, and feeling constantly tired and guilty. The patient has a history of severe meningoencephalitis at the age of 17 requiring four days in the intensive care unit. During that episode, he reported seeing monkeys in his hospital room. On exam, he is a well-appearing, cooperative male in no acute distress. He is alert and oriented with a normal affect. He states that he feels sad and guilty about what happens. He denies suicidal ideation. Which of the following is the most likely diagnosis in this patient?

usmle-11634

A 36-year-old woman is brought to the emergency department for acute onset chest pain. She just returned from Japan 2 days ago and reports 7/10 chest pain that is worse with deep inspirations. Her past medical history is unremarkable. She currently takes oral contraceptives for birth control. A computed tomography scan is performed and demonstrates an embolus at the right lung. She is subsequently started on intravenous heparin with a transition to an oral medication at discharge. Three days after discharge, she returns to the emergency department for skin findings shown in Figure A. She denies any fever, flu-like symptoms, trauma, or abnormal contact. What is the most likely explanation for this patient’s condition?

usmle-11635

A 22-year-old male with a history of difficult-to-treat bipolar disorder with psychotic features is under going a medication adjustment under the guidance of his psychiatrist. The patient was previously treated with lithium and is transitioning to clozapine. Which of the following tests will the patient need routinely?

usmle-11636

A 69-year-old woman comes to the emergency department for pain in her right wrist following a fall. She was walking out from the grocery store when she tripped on something and fell forward, landing on her right hand as she tried to brace her fall. She denies bleeding, paresthesia, or loss of sensation, but endorses a 7/10, sharp, stabbing pain in her right wrist. Her past medical history is significant for obesity, hypertension controlled with lisinopril, and myositis managed with glucocorticoids. She used to smoke 1-2 cigarettes over the weekend when she was in her thirties. The patient reports that she weight lifts 3 times a week. A physical examination demonstrates a swollen wrist and tenderness upon palpation along the right wrist and distal forearm. A radiograph of the right wrist is obtained and is shown in Figure A. Which of the following is a risk factor for her condition?

usmle-11637

A 51-year-old police officer is brought to the emergency room after being shot in the abdomen. His wound was packed and bandaged by emergency medical services before he was transported to the hospital. His past medical history is notable for hypertension and diabetes. He takes metformin and lisinopril. He has a 20-pack-year smoking history and does not drink alcohol. His temperature is 98.6°F (37°C), blood pressure is 142/86 mmHg, pulse is 120/min, and respirations are 24/min. On exam, he appears uncomfortable but is able to answer questions appropriately. He has a 1 cm x 1 cm wound in the left upper quadrant. There is an exit wound in the left lower back. After undergoing the appropriate laboratory and imaging tests, he undergoes a diagnostic laparotomy. No involvement of the colon or small intestine is noted intraoperatively. He is placed on the appropriate antibiotic and pain control regimens. Three days later, he experiences several episodes of non-bloody diarrhea. His temperature is 101°F (38.3°C). Sigmoidoscopy reveals multiple pseudomembranous plaques in the sigmoid and descending colon. This patient's symptoms are most likely due to taking an antibiotic that inhibits which of the following enzymes?

usmle-11638

A 42-year-old male presents to his primary care physician complaining of abdominal pain. He reports a 5-month history of epigastric pain that improves with meals. He has lost 15 pounds since the pain started. His past medical history is significant for a prolactinoma for which he underwent transphenoidal resection. He drinks alcohol socially and has a 10 pack-year smoking history. His family history is notable for a maternal uncle with a parathyroid adenoma. His temperature is 98.8°F (37.1°C), blood pressure is 125/80 mmHg, pulse is 85/min, and respirations are 18/min. After further workup, the patient is started on octreotide, an analogue of an endogenously produced hormone. When this hormone is produced by the hypothalamus, it has which of the following effects?

usmle-11639

A primigravid 28-year-old woman delivers a 38-week-old male infant via spontaneous vaginal delivery. She had no prenatal care during her pregnancy. At birth the infant has underdeveloped hands and radiograph reveals missing phalanges in the thumbs. Examination of the buttocks reveals a missing anus. Further work-up reveals flow between the two ventricles on echocardiography and a single kidney on preliminary abdominal ultrasound. The infant also has difficulty feeding that results in coughing and apnea. Which of the following tissues was most likely affected during embryologic development?

usmle-11640

An 11-year-old boy is brought to the emergency department by his parents with a 2-day history of fever, malaise, and productive cough. On presentation, he is found to be very weak and is having difficulty breathing. His past medical history is significant for multiple prior infections requiring hospitalization including otitis media, upper respiratory infections, pneumonia, and sinusitis. His family history is also significant for a maternal uncle who died of an infection as a child. Lab findings include decreased levels of IgG, IgM, IgA, and plasma cells with normal levels of CD4 positive cells. The protein that is most likely defective in this patient has which of the following functions?

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A 61-year-old man presents to the emergency department because he has developed blisters at multiple locations on his body. He says that the blisters appeared several days ago after a day of hiking in the mountains with his colleagues. When asked about potential triggering events, he says that he recently had an infection and was treated with antibiotics but he cannot recall the name of the drug that he took. In addition, he accidentally confused his medication with one of his wife's blood thinner pills several days before the blisters appeared. On examination, the blisters are flesh-colored, raised, and widespread on his skin but do not involve his mucosal surfaces. The blisters are tense to palpation and do not separate with rubbing. Pathology of the vesicles show that they continue under the level of the epidermis. Which of the following is the most likely cause of this patient's blistering?

usmle-11642

A 4-year-old boy is brought by his mother to the emergency room after the child was bitten by a rattlesnake one hour prior to presentation. The child was reportedly playing in the backyard alone when his mother heard the child scream. She rushed out to her child and found a snake with a rattle on its tail slithering away from the child. On examination, the child has a bleeding bite mark and significant swelling over the dorsal aspect of his right hand. He is in visible distress and appears pale and diaphoretic. The child undergoes fluid resuscitation and is placed on supplemental oxygen. He is administered rattlesnake antivenom and is admitted for observation. He is subsequently discharged 24 hours later feeling better. However, 6 days after admission, he presents again to the emergency department with a temperature of 102°F (38.9°C), diffuse wheals, and knee and hip pain. This patient’s condition is caused by which of the following?

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A 2-year-old boy is brought the his primary care physician for persistent failure to thrive. He has not been meeting normal motor developmental milestones. Further questioning reveals a family history of congenital kidney disorders, although the parents do not know details. Based on clinical suspicion a panel of lab tests are ordered which reveal a sodium of 129 mg/dL (normal range 136-145), a potassium of 3.1 mg/dL (normal range 3.5-5.0), a bicarbonate of 32 mg/dL (normal range 22-28) and a pH of 7.5 (normal range 7.35-7.45). Urinary calcium excretion is also found to be increased. Which of the following drugs has the most similar mechanism of action to the most likely diagnosis in this patient?

usmle-11644

A 54-year-old male presents to clinic complaining that he is not sleeping well because he has to get up from bed to urinate multiple times throughout the night. He says that he strains to void, has terminal dribbling, and has urinary urgency. Past medical history is significant for orthostatic hypotension. On digital rectal exam, you note symmetric firm enlargement of the prostate. Free Prostate-Specific-Antigen (PSA) level is 4.6 ng/mL. Before you finish your physical exam, the patient asks if there is anything you can do for his male-pattern baldness. What is the mechanism of action of the drug that would pharmacologically treat this patient’s urinary issues and his male-pattern baldness?

usmle-11645

A 52-year-old G3P3 presents to her gynecologist complaining of painful intercourse. She reports a 6-month history of intermittent dryness, itching, and burning during intercourse. Upon further questioning, she also reports poor sleep and occasional periods during which she feels very warm and sweats profusely. Her past medical history is significant for poorly controlled hypertension and a 10 pack-year smoking history. She takes hydrochlorothiazide and enalapril. Her temperature is 99.3°F (37.4°C), blood pressure is 135/85 mmHg, pulse is 90/min, and respirations are 18/min. On examination, she is a healthy female in no distress. Pelvic examination reveals no adnexal or cervical motion tenderness. Which of the following sets of hormone levels are most likely to be found in this patient?

usmle-11646

A 30-year-old woman presents to clinic for for a routine checkup. She reports that she is in good health but that she felt short of breath on her hiking and skiing trip to Colorado the week prior. She explains that this was the first time she has gone that high into the mountains and was slightly concerned for the first few days because she felt chronically short of breath. She reports a history of childhood asthma, but this experience did not feel the same. She was on the verge of seeking medical attention, but it resolved three days later, and she has felt fine ever since. What other listed physiological change results in a physiologic alteration similar to that which occurred in this patient?

usmle-11647

A 58-year-old male comes to the clinic complaining of joint pain and diarrhea. He reports that for the past year he has been experiencing aches at various joints including the knees, wrists, and elbows. There is no temporal pattern, and nothing seems to make it better. About 3 months ago he noticed that his stool would float and was difficult to flush. “It seems to get worse when I eat bread but I can’t be sure,” he claims. He reports a 10-pound unintentional weight loss over the past 2 months, fatigue, and diarrhea. He denies ulcers, fever, night sweats, chest pain, or palpitations. A histological sample of his endoscope sample is shown in Figure A. What is the best treatment for this patient?

usmle-11648

A 24-year-old male was in a motor vehicle accident that caused him to fracture his femur and pelvis. After 2 days in the hospital, the patient became delirious, tachypneic, and a petechial rash was found in his upper extremities. Which of the following is most likely responsible for this patient’s symptoms?

usmle-11649

A 57-year-old man presents to his physician with the complaint of a painful toe joint on his right foot. He states that the onset of pain came on suddenly, waking him up in the middle of the night. On physical exam, the metatarsophalangeal (MTP) joint of the big toe is swollen and erythematous. The physician obtains information regarding his past medical history and current medications. Which of the following medications would have the potential to exacerbate this patient’s condition?

usmle-11650

A 17-year-old boy is brought to the physician by his parents who are concerned about his bizarre behavior. Over the past three months, he has become withdrawn from his friends and less interested in his classes and extracurricular activities. On several occasions, he has torn apart rooms in their home looking for “bugs” and states that the President is spying on him because aliens have told the government that he is a threat. Although he has always been quite clean in the past, his father notes that the patient’s room is now malodorous with clothes and dishes strewn about haphazardly. He also says that sometimes he can hear the devil speaking to him from inside his head. He has no medical problems, does not drink alcohol or use any drugs. Physical examination of the boy reveals no abnormalities. On mental status examination, the boy is oriented to person, place and time. He avoids eye contact and replies mostly with monosyllabic responses. He appears distracted, and confirms that he is hearing whispering voices in his head. What is the most appropriate diagnosis for this patient?