A 46-year-old man sustains severe head and abdominal injuries in a motor vehicle collision.  He has no other medical conditions.  Initial emergency assessment establishes a Glasgow Coma Scale rating of 6 on a scale of 3-15.  Blood pressure is 84/50 mm Hg and pulse is 122/min.  The patient is successfully resuscitated and placed on a ventilator.  Two days later, he develops tachypnea and severe hypoxemia.  Chest x-ray obtained at this time is shown in the image.

Which of the following pathologic changes most likely led to the development of this patient’s current condition?

A 60-year-old man is brought to the hospital with acute chest pain and shortness of breath.  Laboratory studies show elevated troponin and increased creatinine.  The patient develops cardiac arrest and cannot be resuscitated.  Histological findings of his renal tissue are shown on the slide below:

Which of the following is the most likely cause of this patient’s kidney disease?

A normal volunteer undergoes an invasive cardiac electrophysiology study as part of a project to characterize action potential transmission through the cardiac conduction system.  Action potential propagation velocity is measured at 4 points (in m/sec) within the heart.  The following results are obtained:

Point 1 – 1.1 m/sec

Point 2 – 0.05 m/sec

Point 3 – 2.2 m/sec

Point 4 – 0.3 m/sec

Which of the following locations most likely corresponds to point 2?

A 62-year-old man comes to the office for evaluation of progressively worsening right hip pain that is unresponsive to over-the-counter analgesics.  He was diagnosed with Paget disease of bone several years ago and has been taking risedronate.  The patient has chronic, mild, bilateral hearing loss that is unchanged.  His only other medical condition is asthma, for which he uses corticosteroid and bronchodilator inhalers.  Vital signs are normal.  Range of motion at the hip is normal, with no effusion or erythema.  An x-ray of the right hip demonstrates an area of mixed lysis and sclerosis with focal periosteal elevation and reactive new bone formation.  Which of the following is the most likely cause of this patient’s current symptoms?

A 32-year-old woman comes to the hospital due to “something stuck in my throat.”  Her symptoms have been present for an hour and are worse when she tries to swallow saliva.  The patient has no associated pain or weight loss.  Past medical history is significant for migraine headaches.  Temperature is 36.6 C (97.9 F), blood pressure is 112/76 mm Hg, pulse is 95/min, and respirations are 20/min.  The oropharynx is normal, and neck examination shows no abnormalities.  Neurologic examination shows no abnormalities.  A barium swallow is unrevealing.  Upper gastrointestinal endoscopy also reveals no abnormalities.  Which of the following is the most likely diagnosis?

A 54-year-old man comes to the emergency department due to acute right knee pain that started within the last 24 hours.  The patient has severe pain associated with local redness, swelling, and subjective fever; he is unable to bear weight on the right lower extremity.  His medical history is notable for heavy smoking and ischemic cardiomyopathy, and he was recently admitted to the hospital for decompensated congestive heart failure.  Temperature is 37.5 C (99.5 F), blood pressure is 105/65 mm Hg, and pulse is 104/min.  On examination, the patient appears to be in significant pain with grimacing and diaphoresis.  The right knee is moderately erythematous and tender, and he has severe pain with passive motion.  Synovial fluid aspiration is performed, and microscopic findings are shown in the image below.

Which of the following is the most likely cause of this patient’s symptoms?

A 23-year-old woman comes to the office due to crampy abdominal pain that begins 1-2 days before menses and subsides 2-3 days afterward.  The patient has experienced this pain, which she describes as moderate to severe, for the past 4 years.  She was prescribed ibuprofen and oral contraceptives last year, but they provided minimal pain relief.  Menarche was at age 10; menses last for 7 days and occur every 29 days.  Pelvic ultrasound reveals a right-sided pelvic mass that measures 3 × 4 × 4 cm.  Diagnostic laparoscopy reveals an enlarged right ovary that is adherent to the pelvic side wall.  The right ovary is removed, and microscopy shows the findings seen below.

Which of the following is the most likely diagnosis?

A 39-year-old woman, gravida 1 para 0, comes to the office for a prenatal visit.  The patient is at 27 weeks gestation by last menstrual period and has received no previous prenatal care.  She has had no vaginal bleeding, leakage of fluid, or contractions.  The patient has chronic hypertension.  On examination, BMI is 19 kg/m², and the uterine fundus measures 22 cm.  A transabdominal ultrasound reveals a severely growth-restricted fetus with pulmonary hypoplasia and bilateral small, underdeveloped kidneys.  Measurement of the amniotic fluid shows oligohydramnios.  Which of the following is the most likely cause of this patient’s presentation?

A 26-year-old woman comes to the office due to a 1-day history of nonproductive cough, severe myalgias, and malaise.  She has no medical problems and does not smoke cigarettes.  The patient has never traveled outside the United States.  A work colleague recently had similar symptoms and had to stay home for several days.  The patient’s temperature is 38.4 C (101.1 F).  On physical examination, she has no cervical lymphadenopathy, oropharyngeal erythema, tonsillar exudates, or lung crackles.  Following a positive nasopharyngeal swab test result, the patient is started on a medication that is directed specifically against the causative agent, thereby minimizing the duration of symptoms.  This medication most likely acts by directly inhibiting which of the following processes?

A researcher adds a radiolabeled amino acid to a cell line that is actively producing protein.  Three samples of cell protein extracts are obtained at 10, 15, and 25 minutes after the radiolabeled amino acid is added, and subsequently subjected to gel electrophoresis on an SDS polyacrylamide gel represented in the image below:

Based on the observed pattern of protein expression, the cell line is most likely producing which of the following?

A study is performed using lymphoid cells from a 46-year-old woman with a history of prolonged painless lymphadenopathy.  The patient’s abnormal lymphoid cells and healthy control cells are grown in separate cultures containing interleukins.  When interleukins are withdrawn, the population of control cells rapidly decreases, whereas the number of patient cells remains stable.  Agarose gel electrophoresis of DNA extracted from the control cells shows fragments in multiples of 180 base pairs; the DNA from the patient cells is unfragmented.  Which of the following features of this patient’s cells best explains this finding?

A researcher is studying the effects of various drugs on bronchial smooth muscle physiology in an animal model.  He first excises a segment of bronchial tissue from the lung of a guinea pig and subsequently isolates a strip of smooth muscle.  The bronchial smooth muscle fragment is then submerged in a physiologic solution, and muscle contraction is measured in the presence of different drugs.  The obtained results are shown in the graph below.

Drug Y in this experiment is most likely to be which of the following?

A 70-year-old woman and a 25-year-old man are each given single doses of diazepam for panic attacks.  Diazepam plasma levels in each patient over time are plotted on the graph below.

The 70-year-old woman is more likely to experience which of the following?

A 16-year-old boy is brought to the emergency department due to progressive confusion and agitation for the past several hours.  His friends report that he started to act “bizarre” after chewing some plant seeds.  They state that he said bugs were crawling on his skin, and that he was talking to people who were not there.  The patient himself reports blurred vision.  He also frequently interrupts emergency department staff to ask for drinking water.  Medical history is unremarkable.  The patient occasionally smokes cigarettes and marijuana.  He is uncooperative with examination, but his mucous membranes appear dry and skin is warm and flushed.  This patient’s presentation is most similar to an overdose of which of the following drugs?

A 34-year-old woman comes to the office to discuss the results of recent genetic testing.  She and her husband are of normal stature, but 2 of their 3 children have developed achondroplasia.  There is no history of achondroplasia on either side of the family.  To determine the causal mutation, blood was collected from the affected children, DNA was extracted from peripheral leukocytes, and the fibroblast growth factor receptor (FGFR) gene was analyzed.  Both affected offspring were found to be heterozygous for the same mutation in the FGFR gene.  Which of the following is the most likely explanation for this unaffected couple having children with the disorder?

A 54-year-old woman was diagnosed with type 2 diabetes mellitus two years ago.  Her glycemia is reasonably well controlled with oral metformin.  She exercises regularly.  Her mother died of a stroke at 65 years old.  Her father suffers from hypertension, osteoarthritis, and kidney stones.  Her blood pressure is 130/80 mm Hg and her heart rate is 76/min.  BMI is 32 kg/m².  Which of the following regular activities is most recommended in this patient?

A 29-year-old man comes to the physician with fever, fatigability, and sore throat.  He does not respond to antibiotic treatment and is subsequently hospitalized.  Peripheral blood smear examination is shown in the image below.

Which of the following chromosomal abnormalities is most likely present in this patient?

A 23-year-old man enrolls in a study on immune system activity.  He has no significant medical history other than occasional upper respiratory illnesses and has received all age-appropriate vaccinations.  He takes no medications and does not use tobacco, alcohol, or illicit drugs.  There is no family history of immune disorders.  Physical examination shows no abnormalities.  During an experiment, cells from his peripheral blood are isolated and incubated with various viral antigens.  Levels of several cytokines are measured before and after incubation.  A rise in the level of which of the following cytokines would most specifically demonstrate the presence of activated lymphocytes in this experiment?

A 32-year-old woman comes to the clinic due to several “spots” on her face for the past 3 weeks.  The lesions have gradually increased in size and are becoming more numerous.  They are mildly pruritic, but the patient has no pain or fever.  On examination, multiple papular lesions are noted on the trunk and face, as shown in the image below.

Biopsy of these lesions will most likely show which of the following histopathologic findings?

The duodenum is sampled in experimental animals after applying various stimuli.  Which of the following triggers copious bicarbonate-rich fluid accumulation in the duodenum?

A 17-year-old boy sustains a blow to the right knee while playing hockey and is brought to the emergency department with severe knee pain.  He was skating at high speed when he collided with the wall of the ice rink, impacting forcefully against the anterior aspect of his right knee.  The patient required urgent transport to the emergency department due to gross deformity of the leg.  Medical history includes a dental fracture and numerous sports-related contusions.  Development has otherwise been normal.  Physical examination reveals posterior displacement of the tibia relative to the femur, with significant bruising and swelling around the knee.  Which of the following structures is most likely to be injured in this patient?

A 37-year-old woman, gravida 2 para 1, comes to the emergency department with lower abdominal pain, fever, and chills on postoperative day 5.  The patient underwent an emergency cesarean delivery due to fetal concerns at 39 weeks gestation after 20 hours of labor.  She had a normal postpartum course and is breastfeeding her infant.  Her prenatal laboratory studies were negative for infection.  The patient has a history of chlamydia that was treated with antibiotics 4 years ago.  Temperature is 38.9 C (102 F), blood pressure is 110/70 mm Hg, and pulse is 110/min.  Physical examination reveals a tender lower abdomen and foul-smelling vaginal discharge.  Breast examination is normal.  There is no costovertebral tenderness.  Laboratory results show leukocytosis with a neutrophilic predominance.  Which of the following is the site of infection in this patient?

A 4-year-old girl is brought to the physician by her father for evaluation of a painful rash affecting the right lower extremity.  He says that his daughter has had no significant medical problems other than some colds and a couple of generalized rashes when she was younger.  Physical examination shows the findings seen below.

Which of the following is the most likely diagnosis in this patient?

A 32-year-old man comes to the office due to mild depression and is referred for psychotherapy.  During treatment, he discusses how rageful he feels every time he recalls childhood episodes of physical abuse by his stepfather.  The patient is a devoted father to his two young children and a kind and supportive coach of a youth soccer team.  He recently joined a rugby club, where he is known as a fierce competitor.  Which of the following defense mechanisms is illustrated by this patient?

A cancer cell biologist is evaluating overexpression of growth factor receptors as a mechanism for oncogenesis.  In the laboratory, she isolates and purifies the cell-surface receptor for the HER2/neu protein.  Structural analysis reveals that the receptor is of the epidermal growth factor receptor family.  It is shown to have intrinsic tyrosine kinase activity.  Based on these data, which of the following is the most likely immediate effect of ligand binding to this receptor?

A 28-year-old man comes to the office for a routine health maintenance evaluation.  Blood pressure is 140/90 mm Hg and pulse is 100/min.  Weight has increased from 70 to 81 kg (154.3 to 178.6 lb), and he has a ruddy appearance.  The patient states that his alcohol intake has increased from a glass of wine occasionally to 4 glasses daily.  He says, “My mother passed away 3 months ago and then I lost my job.  Now my wife is talking about leaving me.  The only thing that makes me feel better is a few glasses of wine.”  Which of the following responses is the most appropriate at this time?

A 24-year-old student comes to the clinic with chronic nasal congestion and occasional headaches.  Her symptoms have worsened over the last 3 months.  The patient has no associated fever, wheezing, or shortness of breath.  She has been using over-the-counter oral loratadine without relief.  Past medical history is unremarkable.  Physical examination reveals atrophic nasal mucosa and a thinned nasal septum with a small septal perforation.  Oral and pulmonary examinations are normal.  Which of the following is the most likely cause of this patient’s symptoms?

A 32-year-old male sustains a knife injury to his back and undergoes a right nephrectomy.  His past medical history is insignificant.  Which of the following best describes his glomerular filtration rate (GFR) compared to baseline?

A 56-year-old man comes to the office to discuss sexual dysfunction.  For the last 3 years, he has had increasing difficulty achieving and maintaining an erection, although his libido has been normal.  The patient has no nocturnal erections.  Past medical history is notable for type 2 diabetes mellitus, hypertension, and hypercholesterolemia, for which he takes appropriate medications.  Blood pressure is 135/83 mm Hg and pulse is 76/min.  On examination, there are no genital lesions.  Testes are normal in size and firmness.  Laboratory tests show a normal serum testosterone level and adequate control of diabetes.  The patient is prescribed a medication that inhibits the isoenzyme phosphodiesterase-5, which leads to improved erectile function.  Which of the following areas indicated on the image below is the primary site of activity of this medication?

A 10-year-old boy is evaluated for progressively worsening headaches, vomiting, and visual disturbances.  The headaches are worse at night and occasionally awaken him from sleep.  He drinks large amounts of water and has to urinate frequently.  The patient has no history of head trauma or loss of consciousness.  There is no family history of migraines.  Temperature is 36.7 C (98.1 F), blood pressure is 140/80 mm Hg, pulse is 60/min, and respirations are 10/min.  Height and weight are below the 5th percentile for age and sex.  MRI of the brain is ordered.  Which of the following findings on visual field examination would be most characteristic of this patient’s disease process (black shading indicates loss of vision)?

A 48-year-old woman is hospitalized for lobar pneumonia.  Blood and sputum cultures are ordered, and appropriate antibiotic therapy is started.  After 3 days of treatment, the patient continues to have persistent fever and chills.  Imaging studies reveal right-sided empyema.  Tube thoracostomy is performed and drains a large volume of pus; broad-spectrum antibiotics are continued.  The patient’s fever subsides, but she develops difficulty raising her right arm above her head.  When she pushes against a wall with outstretched arms, there is prominence of the right scapular angle.  Which of the following muscles is most likely affected?

A researcher is studying the chemical composition of secretions from various tissues.  Micropipettes are placed in the lumen or duct of several different organs of an experimental animal and secreted fluid is extracted.  Various stimuli are applied to increase the rate of fluid secretion.  The graph below shows the concentrations of several electrolytes in relation to secretion flow rate.  Which of the following organs most likely secreted fluid with the chemical composition shown below?

An 18-year-old college student comes to the office due to severe anxiety and episodes of “heart pounding.”  She witnessed a car accident with multiple fatalities 3 weeks ago.  The patient awakes multiple times each night in a cold sweat and has trouble falling back asleep.  During the day, she keeps seeing the accident and obsesses about steps she might have taken to help the injured.  The patient has avoided leaving her home as any loud traffic sounds cause her to panic with a racing heart and dizziness.  She has also felt sad and guilty for not helping more and finds it difficult to be around friends and family.  The patient had to postpone her recent final exams because she found it impossible to study.  She has no psychiatric or medical history.  Which of the following is the most likely diagnosis?

A 25-year-old woman is brought to the office by worried family members.  They report that she recently cut off all communication with friends and spends most of each day alone in her room with her tarot cards.  The patient says that she is trying to interpret signs from God so that she can resist the power of the devil.  Over the past 2 months, she has heard the devil’s voice and suspects that her internal organs have been replaced by somebody else’s.  The patient has no medical history and does not use alcohol or illicit drugs.  Physical examination shows no abnormalities.  On mental status examination, she is disheveled, makes poor eye contact, and has a flat affect.  Which of the following is the most likely diagnosis?

A new screening test is positive for disease X in 250 out of 1,000 affected patients and in 100 out of 1,000 healthy controls.  The screening test is then applied to a population where the disease prevalence is 10,000/100,000.  How many false positives would be expected per 100,000 individuals in this population?

A group of women between ages 30 and 40, all of whom have a point mutation in fibroblast growth factor receptor 2 (FGFR2), are followed for five years.  Thirty of the women develop breast cancer during this period and 65 do not.  A second group of women without the mutation is also followed for five years.  Twenty women in this group develop breast cancer and 75 do not.  Which of the following best describes the relative risk of breast cancer in women with the FGFR2 mutation?

Conventional chemotherapy is given to a group of 500 patients with squamous cell lung cancer.  A year after diagnosis, 100 patients are still alive.  A new chemotherapy regimen is tested in a separate group of 100 patients.  Forty-five of the patients treated with the new chemotherapy regimen are still alive a year after diagnosis.  How many patients need to be treated with the new chemotherapy regimen to save 1 additional life as compared with the conventional regimen?

A 19-year-old woman comes to the hospital due to 4 days of severe abdominal pain and nausea.  She has also had reddish-brown discoloration of her urine but no dysuria or increased urinary frequency.  Her boyfriend adds that she has become restless and irritable and has had several aggressive outbursts since she began to feel unwell.  The patient had a similar episode at age 13 but has not had any symptoms since.  She recently started taking combined oral contraceptives but takes no other medications.  Her temperature is 37 C (98.6 F), blood pressure is 120/70 mm Hg, and pulse is 110/min and regular.  On examination, she is anxious and her abdomen is soft with mild generalized tenderness on deep palpation.  She has no skin rash.  Which of the following conversions is most likely impaired in this patient?

A 32-year-old man with a history of HIV is brought to the emergency department in January due to worsening headache and confusion.  The patient had been acting inappropriately over the past 2 days.  Today, he assaulted a coworker because she was “staring” at him.  The patient takes antiretroviral medications, and his CD4 count was 400/mm³ a month ago.  Temperature is 38.3 C (100.9 F).  The patient appears lethargic.  Pupils are equal and reactive to light and funduscopy is normal.  The patient moves all extremities equally.  There are no skin lesions.  MRI of the brain reveals temporal lobe findings as shown in the image.

Which of the following tests is most likely to establish the diagnosis in this patient?