USMLE Q Bank Qs

Question 1

An isolate of S. Pneumo from a patient with meningitis is incubated with low-dose radiolabeled ceftriaxone and then subjectedto protein electrophoresis. 5 distinct bands are detected by radioautography. The bandsmost likely represent radiolabeled ceftriaxone that is bound to transpeptidases. An isolate of S. Pneumo from a patient with meningitis is also incubated with low-dose radioactive ceftriaxone and subjected to protein electrophoresis. Only 2 bands aredetected using radioautography. What best explains the observed finding?

Answer 1

Answer: change in protein structure.

Notes: 3 of the penicillin-binding proteins have been altered in such a way that inhibits the binding of ceftriaxone. Structural changes in penicillin-binding proteins that prevent ceftriaxone from binding is one mechanism for ceftriaxone resistance.
*Beta-lactamases function to degrade PCN & cephalosporins. Production of a beta-lactamase would prevent ceftriaxone from being able to bind to the Penicillin-binding proteins. ecause ceftriaxone is so much smaller than the penicillin-binding proteins, unbound ceftriaxone would likely accumulat at one of the electrodes. This would lead to no bands being found within theelectrophoresis area.

Question 2

A 54 yo male is brought to the ER with a 1-week history of headaches and progressive confusion. He was hospitalized 6 months ago with viral esophagitis and 2 mo ago with pneumocystitis pneumonia. LP is performed and shows a moderate increase in CSF protein concentration and CSF pleocytosis. The latex agglutination test is + for soluble polysaccharide antigen. LM of this patients CSF is most likely to reveal:

Answer 2

Answer: Budding Yeast

Notes: Diagnosis: Cryptococcus Neorofmans. Yeast form only - round or oval encapsulated cells w narrow based buds.
Tx: Amphotericin B & Flucytosine (acute meningitis). Fluconazole for lifelong prophylaxis.

Question 3

A 28 yo woman comes to the ED w eye irritation and double vision. She also complains of recent weight loss, mood swings, and heart palpitations. Her BP is 140/70 mmHg and pulse is 110/min. Physical examination shows bilateral eye redness and severe proptosis. She is prescribed the appropriate medications and sent home. The patient follows up with her primary care physician 2 weeks later. Her eye symptoms have resolved, and examination reveals a significant decrease in proptosis with no eye redness. The drugthat improved her ocular Sx most likely did so by affecting what?

Answer 3

Answer: Inflammatory infiltration.

Notes: Infiltrative opthalmopathy is characterized by edema and infiltration of lymphocytes into the extraocular muscles and CT. Retro-orbital fibroblasts are then stimulated by cytokines released from infiltratingTH1cells to produce xcessive amounts of glycosaminoglycans. The resulting inflammation and accumulation of glycosaminoglycans increases the volume of the retro-orbital tissues. Dysfunction of the extraocular muscles can also cause restricted extraocular movements and diplopia.
-Severe opthalmopathy is characterized by worsening diplopia, extrocular m involvement, and exposure keratitis. High dose glucocorticois. Glucocorticoids can also prevent worsening of opthalopathy induced by radioactive iodine treatment (esp in smokers). Glucocorticoids can decrease peripheral coversion of T4 to T3 but it is their AI effects that improve theopthalmopathy. Antithyroid drugs do not have a direct effect on opthalmopathy.

Question 4

A 22 yo caucasian (f) presents to your office with a recent onset of fever & throat pain. Her past medical history is significant for hyperthyroidism controlled with medical therapy. Her BP is 110/70 mmHg and HR is 90/min. PE is insig. What is the best next step in the management of this patient?

Answer 4

Answer: WBC count with differential.

Notes: Diagnosis=agranulocytosis (absolute PMN count of less than 500/mL). Usually occurs within the first few weeks of therpy. Patients typically present with fever & sore throat.

• moa agranulocytosis: AB v circulating PMN.
• **If thionamide-associated agranulocytosis is suspected, the drug is immediately discontinued and a white blood cell count with differential is drawn.
• NB: ASA & ibuprofen are not the best treatments for fever in a patient with thyroid dysfunction because they can displace TH from binding proteins thereby worsening a thyrotoxic state…acetaminophen is preferred!

Question 5

A 34 yo caucasian female presents to your office complaining of mood swings, difficulty concentrating, and a hand tremor that started only recently. She also admits to having discomfort in her neck. The discomfort radiates to her ears, particularly on swallowing. She ignored the neck & ear discomfort at first because she thought they might be related to flu-like Sx that she had a few weeks ago. Her BP is 140/80 mmHg, and HR is 105/min. You proceeded with a thyroid scan which shows a diffuse decrease in radioactive I uptake. ESR is 105 mm/Hr. Which pathological change in the thyroid gland is most consistent with the clinical sceleraio?

Answer 5

Answer: Mixe, cellular infiltration with occasional multinucleate giant cells.

Notes: Diagnosis=subacute thyroiditis=de Quervain’s thyroiditis = granulomatous thyroiditis.

• PMN–>lymphocyte/histiocyte/multinucleated giant cells.
• thyrotoxic phase–>hypothyroid phase. Self-resolving.

Question 6

A 52 yo Asian male presents to your office with cough, night sweats, and occasional hemoptysis. Sputum cultures placed on a selective medium grow mycobacteria microscopically observed to grow in parallel chains (“serpentine cords”). This observed bacterial growth pattern most strongly correlates with what?

Answer 6

Answer: Virulence.

Notes: Diagnosis=Mycobacterium Tuberculosis. Serpentine pattern refers to the cord factor - a mycoside (2 mycolic acid molecules bound to the disaccharide trehalose). *The presence of cord factor correlates with vrulence; mycobacteria that do not possess cord factor are not able to cause disease. It inhibits macrophage maturation and releases TNF-alpha. It also inactivates PMN & damages mitochondria.
NB: Sulfatides (surface glycolipids) inhibit phagolysosomal fusion.

Question 7

A 55 yo, right-handed man comes to the ER department because of recent onset of severe, throbbing, right-sided orbitofrontal h/a and diplopia. His other medical problems include poorly controlled HTN & chronic tobacco use. Neurologic examination shows that he is awake, alert, and orientated and follows both simplex & complex commands. Testing of the CNs reveals intact visual acuity bilaterally. Visual fields and optic fundi are normal. Exam shows anisocoria, with the right pupil being dilated and nonreactive to both light and accommodation. He has evidence of both vertical & horizontal binocular diplopia. The right eye is down and out with ipsilateral ptosis. The rest of the neurologic examination is within normal limits. CT angiography of the head reveals a large aneurysm in the posterior fossa. Diagnosis?

Answer 7

Compressive aneurysm arising from the right posterior cerebral artery. **The 3rd nerve courses between the posterior cerebral and superior cerebellar arteries as it leaves the midbrain and is susceptible to injury from an expanding aneurysm originating from these vessels. *Chronic smoking & poorly controlled HTN are RF for developing intracranial aneurysms.

• GVE periphery (Parasympathetic fibers): pupillary light and near-reflex pathways - more susceptible to injury from ischemia (small-vessel disease due to diabetes mellitus).
• GSE within the interior and subserve the skeletal muscles of the orbit (superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae superioris. More susceptible to injury from a compression.

Diagnosis - non-pupil sparing third nerve palsy on right. Same for compression of posterior cerebral artery & superior cerebellar artery. *Anterior Inferior Cerebellar Artery can compress the facial artery and vestibulocochlear.

Question 8

A 34 yo male is brought to the ER with severe h/a, blurred vision, hand tremor soon after dining at a local Pizza restaurant. His past medical history is significant for severe atypical depression. His BP is 210/130 mmHg and HR is 110/min. The medication used to treat this patient’s depression is most likely affects waht?

Answer 8

-Answer: enzymatic monoamine degradation.

Notes: This patient is in hypertensive crisis due to couse of MAOi + pizza (cheese - tyramine) - sympathimimetic.

Question 9

A 36 yo caucasian male presents to your office complaining of periodic involuntary deviation to the right, accompanied by muscle pain in his neck. The spells start spontaneously, last 30-40 minutes, and can sometimes be suppressed by placing a hand on the chin. This patient’s condition can be best characterized as which of the following?

Answer 9

Answer: Dystonia.

Notes: Dystonia - SUSTAINED (v myoclonus) involuntary muscle contractions, which force certain parts of the body into abnormal sometimes painful movements or postures. eg - spasmodic torticollis*, blepharospasm (uncontrollable blinking–>complete closure of eyelids), writer’s cramp.

• Myoclonus: sudden, BRIEF, sometimessevere (shock-like) muscle contraction. Hiccups and hypnic jerks. Pathological myoclonus seen in epilepsy & Creutzfeldt-Jakob disease.
• Chorea: involuntary muscle activity that “flows” from one muscle group to another. Movements may appear fragment or JERKY, and the patient may display a “dancing” gait.

Question 10

Malignant Hyperthermia

Answer 10

• HSN of skeletal muscles to inhalation anesthetics (esp halothane) & m relaxant succinylcholine.
• Susceptibility AD.
• Defect in Ryanodine R of SR (located on surface of SR of skeletal muscles & is a Ca2+ channel) - relase small amounts of Ca2+ in the cytoplasm of m fiber during m contraction. AbnL ryanodine R releases large amts of Ca2+ after exposure to anesthetic –> ATP-dependent reuptake by SR. Excessive consumption of ATP gnerates heat; loss of ATP along w high T induces m damage. Rhabdoyolysis–>release of K+, Myoglobin, creatine kinase!!!
• Fever, m rigidity. Tachy, HTN, hyperkalemia, myoglobinemia.
• Tx=Dantrolene=muscle relaxant effective in malignant hyperthermia - it acts on ryanodine R and prevents further release of Ca2+ into the cytoplasm of m fiers.

Question 11

A large, multinational research institute is conducting experiments on human circulatory physiology. The oxygen content of aortic blood is measured in an apparently healthy 35 yo volunteer at rest. Which of the following anatomic sites would normally have a blood O2 content that differs the most from the value obtained from this healthy volunteer’s aorta?

Answer 11

Answer: coronary sinus.

Notes:

1) The heart muscle is perfused during diastole and consumes approximately 5% of CO. Myocardial contraction during systole leads to dompression of the coronary arteries and disruption of BF. Contraction force is highest in endocardium–>severe coronary vessel compression in this area.
2) Myocardial oxygen requirement very high. The heart has a capillary density far exceeding that of skeletal muscle. Oxygen extraction from arterial blood is very effective wtihin the heart: resting myocardium extracts 75%-80% of O2 from blood, while myocardium at work extracts up to 90%.
3) Coronary flow is regulated by local metabolic factors including hypoxia and adenosine accumulation.

Question 12

Histological evaluation of a portion of GI tract shows ramified, tubular glands located in submucosal layer. The glands contain secretions with pH close to 9.0. Which of the following portions of the GI tract is most likely inspected?

Answer 12

Answer: Duodenum.

Notes:

• Duodenum: villi covered by simple columnar epithelium w BB interspersed with goblet cells & APUD (amine precursors uptake and decarboxylation) cells. Crypts of Lieberkuhn. Brunner’s Glands*.
• Jejunum: villi contain more goblet cells than Duodenum. Lymphocytic infiltration common.
• Ileum like jejunum + peyers patches.

Question 13

A 21 yo female is taking meds for a recently diagnosed medical problem. While at a college party, she develops facial flushing, h/a, n/v, abd cramps immediately after having an alcoholic drink. The patient is most likely being treated for what condition?

Answer 13

Answer: Trichomonas vaginitis.

Notes: Drug: metronidazole. It’s used to treat trichomonas vainitis and bacterial vaginosis and giardiasis.

• Interaction w alc from inhibition of alcohol oxidizing enzymes, which causes acetaldeyde to accumulate.
• Candida vaginitis is treated w fluconozole.

Question 14

G+ bacteria are inoculated under the skin of experimental animals and then the infection is treated with antibiotics. Bacteria isolated from the injection site several days later assume a spherical configuration when placed in an isotonic solution and disintegrate rapidly when placed in a hypotonic solution. Which of the following a/b was most likely used in this experiment?

Answer 14

Answer: Cefuroxime.

Notes: G+ has cytoplasmic membrane & peptidoglycan cell wall ouside of that cell membrane. The peptidoglycan cell wallprovides the shape of the bacterium + resistance to osmotic stress*
^PCN, cephalosporin, vancomycin.

Question 15

A 7 yo patient presents to your office accompanied by his parents. He has been hospitalized multiple times for painful episodes in his hands & feet over the last seeral years. He has no known medical problems and takes no meds except for acetaminophen for pain control. You suspect that he has a valine for glutamic acid substitution at position 6 of the beta-globin chain of the Hb molecule. This patient’s Hb would most likely aggregate upon what?

Answer 15

Answer: Oxygen unloading.

Notes:

• Sickling is promoted by conditions associated with low O2 levels, increased acidity, or low BV (dehydration). - Organs in which blood moves slowly (eg - splen, liver, kidney) are predisposed to lower O2 levels or acidity. In addition, organs with particularly high metabolic demands (eg - brain, muscles and placenta) promote sickling by extracting more O2 from the blood.
• Valine (nonpolar) replaces glutamic acid (+): each chain has several alpha helical stretches (secondary structures) and beta bends (tetiary structure) - substitution of valine for glutamic acid does not result in significant change in beta folding.
• 2-3-DPG binds the 2 beta chains by ionic bonding and stabilizes the taut (T) deoxyHb. TThis binding decreases the O2 affinity of Hb and facilitates the release of O2 at this tissue level. With depletion of 2,3 - DPG, the affinity of Hb for O2 will increase and result in uptake of O2 by Hb. Oxygenated HbS does not polymerize; thus, sickling of erythrocytes will be decreased

Question 16

During kidney transplantation in a patient with end-stage polycystic kidney disease, the surgeon notices that the graft becomes cyanotic and mottled soon after he connects graft vessel with recipient vessels. The blood flow to the graft eventually ceases and no urine is produced. What is happening?

Answer 16

Answer: AB-mediated HSN.

Notes: Diagnosis=hyperacute rejection of a renal transplant. Usually diagnosed in operating room because the kidney immediately becomes cyanotic & mottled upon anastomosis of the donor & recipient BV and initial perfusion of the organ.

• BF through the new organ ceases immediately due to fibrinoid necrosis of small vessels + rapid formation of extensive thrombosos within the transplanted organ.–>necrosis of the glomeruli & renal cortex, and urine is frequently never produced.
• Hyperacute rejection is an antibody-mediated reaction that is cuased by preformed antibodies within the recipient that are directed against donor antigens. eg - ABO, anti-HLA. T2 HSN.
• Cell-mediated HSN is the immune etiology for acute solid organ transplant rejection & describes the mechanism for T4 HSN.
• GVHD: only occurs in cases where competent donor T-cells are transplanted into a patient who does not possess a functional immune system. Usu in setting of BM transplantation, also in SCID pt receiving blood transfusion w T-lymphocytes. Usu @ skin liver kidney, gut. Diffuse macular eruption @ palms, soles, back, neck. Whole body generalization + bulla formation.

Question 17

A 57 year old caucasian male is hospitalized with muscle pain, fatigue, and dark urine. His past medical history is significant for stable angina. The patient’s medications include metoprolol, atorvastatin, and ASA. Lab eval reveals that he is in acute renal failure. What med is most likely to have precipitated this patient’s condition?

Answer 17

Answer=Erythromycin

Notes:

• Myopathy is a rare complication of statin use - muscle pain + serum creatine kinase over 10 X the upper limit of normal.
• Erythromycin inhibits cytochrome 3A4. Other macrolides such as clarithromycin also inhibit CYP3A4.
• Other inhibitors of CYP3A4 include ketoconazole, cyclosporine, HIV protease inhibitors, and grapefruit juice.
• If a pt is on an angent that inhibits cyp450 3A4, pravastatin is the statin of choice.

-Acute renal failure is a possible sequela of rhabdomyolysis.

Question 18

A 21 yo laboratory worker experiences rapid-onset breathing difficulty, palpitations, and flushed skin. He has no significant past medical history and takes only loratadine for seasonal allergies. The patient is suspected to have accidental poisoning. Amyl nitrite from a laboratory safety kit is immediately administered via inhalation. Amyl nitrate affects the affinity of Hb for what?

Answer 18

Answer: cyanide.

Notes:

• Cyanide binds to a variety of iron-containing enzymes, th emost important is cytochrome a-a3 complex.
• CC Cyanide poisoning: rapidly-developing cutaneous flushing, tachypnea, h/a, tachy, often accompanied by n/v, confusion, and weakness, Respiratory distress & cardiac dysfunction may follow. Lab studies indicate severe lactic acidosis in conjunction with a lessenedd difference bw arterial & venous O2 content (the venous blood still highly oxygenated).
• Nitrites oxidize Hb –> Methemoglobin, which can’t carry O2 but binds tightly to cyanide–>dusky discoloration to skin. *Sodium thiosulfate also used for cyanide poisoning - combines with cyanide to form less-toxic thiocyanate, wich is excreted in the urine.

Question 19

A 35 yo woman comes to the physician because of indurated, painless nodule on her vulva. She has been complaining of occasional h/a and memory loss recently. She has a history of IVDU and multiple sexual partners. Cervical cultures are negative for gonorrhea but a serum VDRL test is positive. LP reveals mild pleocytosis and positive VDRL. What is the vulvar lesion?

Answer 19

Answer: Gumma.

Notes:

1) Primary syphilis: painless ulceration with raised indurated borders (chancre).
2) Secondary syphilis: bacteremic stage of infection and develops 5-10 weeks following resolution of the chancre. Diffuse macular rash that includes the palms and soles. Condyloma lata.
3) Latent syphilis: asymptomatic (early latent within 1 year after resolution of secondary syphilis) and late latent (>1 year).
4) Tertiary syphilis: neurosyphilis (aSx or subacute meningoencephalitis, tabes dorsalis, etc). Ascending aortic aneurysms, aortic valve insuficiency. Gummas - painless indurated granulomatous lesions–>white-gray rubbery lesions and ulcerate. Cutaneous but can be SQ.
* **+VDRL and pleocytosis in CSF diagnositic of neurosyphilis not primary syphilis.

Question 20

Muscle rigidity is observed in an experiment animal that has chemically-destroyed dopaminergic neurons of the SN. The animal’s rigidity fails to improve with continuous dopamine infusion. Which of the following cell communications account for the lack of responsiveness to dopamine?

Answer 20

Answer: tight junctions.

Notes: Remember that dopamine can’t cross the BBB. C

• Capillaries of the BBB are not fenestrated so paracellular passage of fluid & dissolved material doesn’t occur in CNS. The primary mediators of BBB are tight junctions bw the endotheial cells of CNS capillaries.
• Tight junctions - zonula occludens - claudins & occludens.

Question 21

Blood cultures from a 54 yo male recently diagnosed with HL reveal motile g+ rods that produce a very narrow zone of beta-hemolysis on sheep blood agar. Which of the following processes is the most important in eliminating these bacteria from the body?

Answer 21

Answer: CMI.

Notes: Diagnosis=Listeria monocytogenes is a g+ rod that produces a very narrow zone of beta-hemolysis on sheep blood agar, similar to the pattern produced by colonies of beta-hemolytic strep. L Monocytogenes shows tumbling motility @ 22C but can be cultured at T as low as 4C. It is a facultative intracellular parasite and the only g+ bacteria to produce LPS endotoxin!!! Listeria can cause serious disease (meningitis, septicemi) in newborns, preg, elderly, immunocompromised.
-CMI stimulates production of cytokines (IFN gamma, TNF-beta, IL-12) that induce a cytotoxic T cell response and macrophage activation and killing of intracellular Listeria.

Question 22

A 12 yo male is evaluated for ataxia accompanied by episodic erythematous and pruritic skin lesions and loose stools. Laboratory evaluation reveals loss of neutral aromatic amino acids in the urine. This patient’s symptoms would most likely respond to what supplement?

Answer 22

Answer: niacin.

Notes:

• Diagnosis=Hartnup disease: the intestinal and renal absorption of tryptophan is defective. - precursor for nicotinic acid 5-HT, & melatonin.
• CC: aSx, photosensitivity, pellagra-like skin rashes*. Neurologic - ataxia. Neurologic & skin Sx typically wax and wane during the course of this disease.
• The main lab findings in Hartnup disease in aminoaciduria, restricted to the neutral AA (alanine, serine, threonine, valine, leucine, isoleucine, phenylalanine, tyrosine, tryptophan, histidine - branched + aromatic + serine + threonine + alanine). The urinary excretion of proline, hydroxyproline, and arginine remains unchanged, adnd this important finding differentiates Hartnup disease from other causes of generalized aminoaciduria such as Fanconi Syndrome.
• Treatment w nicotinic acid or nicotinamide and high protein diet is okay.

–CC riboflavin deficiency: cheilosis (perleche), glossitis, keratitis, conjunctivitiy,s, photphobia, lacrimation, marked corneal vascularization, seborrheic dermatitis.-B6–>pyridoxal - -phosphate - coenzyme in decarb & transamination of AA. Deficiency–>anemia, peripheral neuropathy, dermatitis.

Question 23

A 5 yo caucasian male is brought to the ER with somnolence, lethargy, and oliguria. He developed diarrhea several days ago that later became frankly bloody. Lab studies sow elevated blood urea nitrogen & creatinine. Peripheral blood smear reveals fragmented erythrocytes. This patient’s condition is most likely related to consumption of which food?

Answer 23

Answer: undercooked beef.

Notes: Diagnosis=HUS:*: tends to occur most commonly in children under 10 yo and in association with treatment of EHEC gastroeneteritis with a/b.
*Most cases of HUS associated with EHEC O157:H7 have been associated with eating undercooked, contaminated ground beef. Person-to-person contact in families and childcare centers is also an important mode of transmission. Infection can also occur after dinking raw unpasteurized milk & swimming in or drinking sewage-contaminated water.

Question 24

A 50 yo female presents with abdominal pain, diarrhea, and weight loss. She was diagnosed with DM 2 months ago. Her serum somatostatin level is highly elevated. Further evaluation reveals biliary stones. Suppression of what hormone is most likely responsible for biliary stones?

Answer 24

Answer: Cholecystokinin.

Notes:
-Somatostatin secreted from pancreatic “delta cells” decreases the secretion ofsecretin, cholecystokinin, glucagon, insulin, and gastrin. Present with hyperglycemia or hypoglycemia, steatorrhea, and gallbladder stones.
-Gallbladder stones from bc of poor gallbladder contractility, which is secondary to inhibition of cholecystokinin release.
NB: usually hyperglycemia bc insulin more prfoundly inhibited than glucagon.
^Steatorrhea from decreased secretion of secretin as well as a decrease in GI motility.
^Decrease in gastrin release–>hypochlorhydria.

Question 25

Ruptured LV free wall

Answer 25

- a complication of ST elevation MI. Days 3-7 after onset of total ischemia. -->cardiac tamponade, which greatly limits ventricular filling during diastole - venous return to heart reduced-->systemic hypoT and pulseless electrical activity. *HypT & SOB. Muffled heart sounds, jugular venous pressure elevation. - The most common cause of death in patient hospitalized for MI is ventricular F (cardiogenic shock) (2/3). - *RF ventricular free-wall rupture following MI: >60 yo, female, pre-existing HTN, absence of LV hypertrophy. First MI (previous MIs may be protective bc fibrosis ).

Question 26

A 45 yo male develops left knee swelling and pain 6 months after a hiking trip to New Hampshire. He has no significant past medical history except for an episode of facial palsy 3 months ago. Which of the following might have prevented this patient's knee condition?

Answer 26

Answer: Ceftriaxone. Notes: Diagnosis=Lyme disease caused by spirochete Borrelia Burgdorferi, which is transmitted by the bite of an Ixodes tick. Lyme disease is an endemic in the NE region of the US & N Eu. *Lyme disease is easily treated with doxy or PCN-type a/b.

Question 27

A 63 yo male with a recent Hx of MI presents to the ER bc of increasing SOB & cough. PE reveals crackles at the lung bases bilaterally and an S3 on cardiac auscultation. His O2 sat is low. Which of the following most likely accounts for this patient's dypsnea?

Answer 27

Answer: decrease lung compliance Notes: * Dyspnea, bibasilar crackles, and the presence of an S3 sound in a patient w a recent MI suggests L heart F. - ventricular contractility decrease-->drop in LV output/increase in end-systolic pressure in LH-->impaired diastolic return of blood from pulm-->increasing pressure in pulm veins & capillaries. Increased hydrostatic P in pulm circulation causes transudation of fluid from pulm capillaries into lung interstitioum. *The presence of fluid in the pulm interstitium decreases lung complaince. * Poor compliance - poor gas exchange since the lungs are not adequately distended. * Functional residual capacity is increased in diseases that increase lung compliance such as the obstructive lung diseases emphysema and chronic bronchitis. Decreased lung compliance is associated with a decreased FRC.

Question 28

A 14 yo AA female with sickle cell anemia complains of progressive exertional dyspnea after a minor febrile illness. Lab eval reveals a Ht of 18% & reticulocyte count of 0.5%. Which of the following viruses is most likely responsible for this patient's current condition?

Answer 28

Answer: non-enveloped single stranded DNA virus. Notes: -severe anemia after a minor febrile illness; BM can't respond appropriately because reticulocyte count not elevated=Aplastic crisis, secondary to parvovirusB19 infection of erythroid precursor cells in the BM.

Question 29

A 76 yo caucasian female is evaluated for painful lesions on her lips and at the corners of her mouth. She is mildly demented and lives alone. Her urinary riboflavin excretion is very low. Activity of which of the following enzymes is most likely decreased in this patient?

Answer 29

Answer: succinate DH. Notes: -rare in US - seen in chronic alcoholics & severely malnourished. -SS: angular stomatitis, cheilitis, glossitis, seborrheic dermatitis, eye changes (keratitis, corneal neovascularization), anemia. -Dx via erythrocyte glutathione reductase assay or eval of urinary riboflavin excretion!!!! - -Metabolic modifications @ herat, liver, kidney - phosphorylation-->FMN-->FAD. -->reduced, energy-carrying states (FMNH2, FADH2). *FMN component of complex 1, AD component of complex II - ETC. -FAD = electron carrier in TCA - cofactor for succinate DH (succinate-->fumarate).

Question 30

A 34 yo male is an unrestrainedpassenger in a MVA, and sustains considerable trauma. He arrives in the ER hypotensive and bleeding from several sites. As part of the resuscitation efforts, the patient receives a blood transfusion. Abdominal US reveals pslenic laceration & blood int he peritoneal cavity. En route to the operating room for an ER laparotomy, the patient complains of difficulty breathing, chills, and pain in the chest and back. Dark-colored urine is seen draining from the urinary catheter. What is the most likely cause of this patient's current condition?

Answer 30

Answer: complement-mediated cell lysis. Notes: Diagnosis: acute hemolytic transfusion reaction. - in addition to chills, SOB, patients may also experience fever, hypoT, DIC, renal F, hemoglobinuria. *Acute hemolytic reactions occur within minutes of starting a blood transfusion and are due to ABO incompatibility between the donor & recipient. *Anti-ABO IC activate C'-->C3a & C5a (anaphylatoxins) & MAC. Anaphylatoxins cause vasodilation & shock, while MAC leads to RBC lysis.

Question 31

A 21-day-old boy is brought to the office by his mother because of a palpable swelling in the child's neck. The child continues to feed well but appears comfortable only when held sideways. He is at the 50th percentile for height, weight, and head circumference. he child favors looking toward the right & cries when his head is turned to the left. There is a firm swelling on the left side of his neck that does not move when the child swallows. The remainder of the examination is unremarkable. Which finding is most likely present prenatally?

Answer 31

Answer: Intrauterine malposition. Notes: Diagnosis: Congenital Torticollis (2-4 weeks of age). - most commonly caused by malposition of head in utero or birth trauma (bbreech delivery)-->SCM injury & fibrosis. - Rarely due to cervical spine deformities, C1-C2 subluxation, cervical vertebral fusion. [r/o w cervical spine radiography]. - Additional msk anomalies: hip dysplasia, metatarsus adductus NB: CONTRACTURE not injury so PE: head tilter toward affected side with chin pointed away from contracture. Soft-tissue mass palpable in inferior 1/3 of affected SCM*. Plagiocephaly (flat head) & facial asymmetry in severe cases.

Question 32

A 34 yo caucasian male whose older brother died of liver cirrhosis is found to have serum ferritin level of 1800 microgram/L. If the disorder runs in the family, the genetic abnormality primarily affects which of the following processes?

Answer 32

Answer: intestinal absorption. ``` Notes: -On the short arm of chromosome 6, the hemochromatosis gene (HFE) encodes an HLA class I-like molecule that appears to affect iron absorption from the GI tract. Missense mutation (cysteine-to-tyrosine @ 282). N Eu descent. ```

Question 33

A 30 yo male is admitted to the intensive care unit after his wife found him unconscious at home. Lab studies show a serum pH of 7.10 and positive serum ketones. His mucus membranes are extremely dry. The wife notes that he has lost a significant amount of weight recently, despite eating and drinking the normal amounts. Treatment is initiated, and the patient's pH improves. However, he now complains of fever, h/a, and eye pain. Examination of the nasal cavity reveals black necrotic eschar adherent to inferior turbinate. What procedure would confirm the diagnosis?

Answer 33

Answer: mucosal biopsy. Notes: Diagnosis: diabetic ketoacidosis ... + facial pain + h/a - mucormycosis. - These fungi proliferate in BV walls, causing necrosis of the downstream tissue. Black necrotic eschar seen in the nasal cavity. * Histo examination of the affected tissue is necessary in order to make the diagnosis of mucormycosis. : **fungi appear as broad nonseptate hyphae with right angle branchng!!! * **DDx: aspergillus, which can also affect paranasal sinuses of immunosuppressed patients, causing ismilar Sx. Aspiergillus with SEPTATE hyphae with V shaped branching (45 angle).

Question 34

A 63 yo female presents to clinic for a routine examination. Her diet consists mainly of fruit & vegetables and she takes a daily multivitamin. Her last menstrual period was 5 years ago. She expresses concern about wrinkles around her eyes that make her "look old." A decrease in which of the following is most likely responsible for this patient's complaint?

Answer 34

Answer: Collagin fibril produciton. Notes: Human skin exhibits evidence of aging by 30-35 years. : Gradual thinning of epidermis + reduction in SQ fat, BV, hair follicles, sweat ducts, sebaceous glands-->skin to become atrophic/vulnerable. *Decrease in amt dermal collagen & elastic fiers. No intrinsic reticular support.

Question 35

A viral protein synthesized in the macrophages of a 22 yo HIV + male is glycosylated and cleaved into 2 smaller proteins in the ER. These newly formed proteins are most likely responsible for which step of HIV infection?

Answer 35

Answer: virion absorption by the target cells. Notes: * HIV polyprotein precursurs: gag, pol, env. * only polyprotein product of the env gene is glycosylated-->gp160...***gp160-->gp120 & gp41 (@ ER, Golgi). - gp120 mediates viral absorption by binding to the CD4 R of susceptible cells, TM gp41 anchors gp120 through noncovalent interactions, mediating the fusion process bw viruses & target cells.

Question 36

A 78 yo male inpatient about to undergo bronchoscopy is premedicated with IM atropine & becomes acutely restless, disoriented, and combative. On physical examination, his pupils are widely dilated and non-reactive to light. An EKG monitor shows sinus tachycardia. What drug will reverse ALL of this patient's Sx & Signs?

Answer 36

Answer Physostigmine. Notes: - In elderly > 70 yo, atropine's t1/2 may be prolonged from its usual 3 hours to up to 10-30 hours due to reduced CL, causing increased susceptibility to toxicity. - Atropine fever, bronchodilation, tachycardia etc. * Physostigmine inhibits acetylcholinesterase both peripherally & centrally (tertiary amine) - Neostigmine & Edrophonium are anticholinesterase drugs too BUT they both have a quaternary ammonium structure that revents penetration of the BBB at moderate doses so would fail to alleviate the patient's CNS symptoms.

Question 37

A 43 yo immigrant from Southern Asia suffers from a cough that has lasted for several months duration. He comes to the clinic today because of recent onset hemoptysis. On further eval, he reports a 15-lb weight loss over the past 4 months. Sputum cultures grow acid-fast bacilli that are susceptible to most antimycobacterial drugs in vitro. Isoniazid monotherapy in this patient would most likely result in: ?

Answer 37

Answer: selective survival of bacterial cells secondary to gene mutation Notes: *This patient most likely has active TB, which should never be treated with drug monotherapy due to the rapid emergence of antibiotic resistance in M. TB. *Isoniazid R specifically occurs by 2 selective gene mutations. The first is a decrease in bacterial expression of the catalase-peroxidase enzyme that is required for isoniazid activation once the drug enters the bacterial cell!!! The 2nd mechanism of R occurs through modification of the protein target binding site for isoniazid. *Tx of active TB: INH + Rifampin + streptomycin, ethambutol, &/or pyrazinamide. NB: INH monotherapy for PPD+ but negative CXR (no evidence of clinical disease).

Question 38

A 22 yo male is found to have serum anti-HAV IgG AB although he denies any vaccination against hepatitis. The laboratory findings most likely indicates what?

Answer 38

Answer: an anicteric viral infection in the past. Notes: - Most Hep A is silent or subclinical="Anicteric"="no jaundice observed"* [acute, self-limited jaundice, malaise, fatigue, anorexia, nausea, vomiting, RUQ pain, aversion to smoking]. - more common in adults. if going to have disease bc less with AB to HAV as living conditions improve!

Question 39

A leak of radioactive material occurs at a plant that handles the disposal of such waste. A # of workers are believed to have been exposed to this material, which contains heavy isotopes. What should be immediately administered to prevent tissue damage in these individuals?

Answer 39

Answer: Potassium Iodide. Notes: first step in the formation of thyroid hormone is energy-dependent transport of inorganic iodide into the thyroid follicular cell. "This "Iodide trapping" is accomplished by the sodium iodide symporter. The thyroid follicular cells also take up other ions such as perchlorate and pertechnetate and even radioactive Iodine - so high levels of any one substance will significantly reduce the uptake of the others* - + KI to a person exposed to radioactive isotopes of iodine by competitive inhibition=less radioactive material will enter thyroid, reducing amt tissue damage.

Question 40

A 56 yo male is admitted to ER with severe chest pain. His initial BP is 240/130 mmHg & HR is 100/min. A BB and nitroprusside infusion is started. Several hours after admission the patient seems confused and disoriented. You noticed that nitroprusside infusion rate is higher than recommended. What needs to be supplied to reverse this patient's condition?

Answer 40

Answer: Sulfur. Notes: - Notriprousside is an antiypertensive with mixed arterial and venous vasodilatory actions. For emergent settings. Given IV continuous infusion and has onset of action within 30 seconds. * Major disadvantage to use of nitroprusside=potential cyanide toxicity. Nitroprusside is initially metabolized to release cyanide and NO. Cyanide is then metabolized in the liver by "liver rhodanase" to thiocyanite, which is eventually excreted in the urine. - Risk increases with higher dosages, greater infusion rates, prolonged use, and renal insufficiency. - SS Cyanide toxicity: altered mental status lactic acidosis. Antidote=Sodium thiosulfate. (Cyanide + S=thiocyanite).

Question 41

A 32 yo female presents to your office complaining of gray vaginal discharge. Wet mount preparations of the discharge reveals moderate leukocytes and numerous squamous epithelial cells covered with adherent bacteria. This patient most likely has an infection with what organism?

Answer 41

Answer: Gardnerella vaginalis. Notes: - Diagnosis=bacterial vaginosis usu caused by g variable rod Gardnerella vaginalis. - alterations in the normal vaginal flora (loss of lactobacilli & overgrowth of mixed anaerobic organisms)-->gray discharge & "fishy" odor esp with KOH ("whiff test"). * Clue cells=vaginal squamous epithelial cells covered in small dark particles (G. Vaginalis organisms). * Tx: metronidazole (or topical regimens).

Question 42

Isoproterenol

Answer 42

Adrenergic agonist that stimulates beta 1 (increases HR & CO) and beta 2 R (bronchodilation, decreases peripheral arterial resistance, increase glucagon?).

Question 43

In an experiment, laboratory animals are subjected to a toxic insult that specifically targets the protein kinesin. What is most likely to be absent from tissues on histological examination?

Answer 43

Answer: secretory vesicles in nerve terminals. Notes: kinesin=microtubule associated motor protein whose function is anterograde transport of intracellular vesicles and organelles toward the plus (rapidly growing) ends of MT. It uses energy derived from ATP hydrolysis to move along the microtubule.

Question 44

DNA exonucleases hydrolytically remove one nucleotide at a time from the end of a DNA chain. Which of the following enzymes has 5' to 3' exonuclease activity?

Answer 44

Answer: DNA polymerase I. Notes: -High fidelity of DNA poly I/II/III accomplished by 3' to 5' "proofreading" exonuclease activity. *Only DNA poly has 5'-->3' exonuclease activity: to remove the RNA primer (3'hydroxyl group) used by DNA polyIII for initiation of DNA rep & perform exonuclease excision and repair of damage to parent DNA.

Question 45

In the experimental setting, certain microorganisms have demonstrated treatment resistance by decreasing ergosterol incorporation into the cell membrane. These organisms would most likely be resistant to which drug?

Answer 45

Answer: Nystatin. 1) Polyenes (amphotericin B & nystatin): bind ergosterol molecules in fungal cell membranes-->pores & causing cell lysis//K+ and other electrolytes leak out. 2) Triazoles (ketoconazole, fluconazole, itraconazole, voriconazole): inhibits ergosterol synthesis! 3) Echinocandins (capsofungin & micafungin): inhibit glucan synthesis ( a cmponent of the fungal cell wall). 4) Pyrimidines: Flucytosine-->5-FU within fungal cell & interferes with fungal RNA & protein synthesis.

Question 46

A small area of the brain of a 54 yo male shows neuronal shrinkage and intense cytoplasmic eosinophilia. If the patient survived, what would the area most likely demonstrate?

Answer 46

Answer: Glial hyperplasia. Notes: Gliosis (astrocyte proliferation) - glial hyperplasia - large #s of fibrils & glycogen granules. Large, vesicular nuclei & prominent nucleoli. *Proliferated astrocytes replace lost neurons & compensate for their volume. Later, after the neuronal death, astrocytic processes form a closely connected firm meshwork called a gliotic scar. -Fibroblast migration to a site of injury occurs in the PNS.

Question 47

A 55 yo male is being treated wtih combo chemo for AML. His last CBC shows a WBC of 800/cmm & a platelet count of 89,000/mm3. He is now admitted with fever, chills, and SOB. His pulse is 120/min & BP is 90/40 mmHg. Which bacteria is most likely responsible for this patient's Sx?

Answer 47

Answer: Pseudomonas Aeruginosa. Notes: - immunosuppressed (neutropenic) male experiencing Sx consisted with bacterial sepsis - Pseudomonas - Ecthyma gangrenosum - from perivascular bacterial invasion of arteries & veins in the dermis & SQ tissue with subsequent release of exotons that are destructive to human tissue. * Exotoxin A (protein synthesis inhibition), elastase, phospholipase C, pyocyanin (-->ROS).

Question 48

A 34 yo caucasian female underwent an uncomplicated cholecystectomy 1 mo ago eats a small meal containing mostly TGs and a small amount of complex carbohydrates. In this patient, most of the dietary lipids would be absorbed in whatpartof the GI tract?

Answer 48

Answer: Jejunum. Notes: - Duodenum: lipid digestion; jejunum: lipid abosprtion. - Cholecystecomy doesn't affect bile acid production so lipids can still be absorbed (micelles-->chylomicrons once in) but can't eat as much fat in one meal bc can't release that much bile acids - also increased enterhepatic circulation bc continual since cannot store bile acids.

Question 49

A 45 yo man comes to the ED bc of a 1 day of severe dyspnea with exertion. He has noticed the condition worsening while walking shorter distances throughout the day. He denies any inciting trauma. He has no other medical problems & takes no medications. He has smoked one pack of cigarettes daily for the past 20 years and does not use alcohol or illicit drugs. He works as a business exec. His BP is 110/60 mmHg & pulse is 96/min. Testing of arterial blood gases drawn on room air shows a PaO2 level of 54 mmHg & a PaCO2 level of 26 mmHg. What is most likely to be associated with this patient's condition?

Answer 49

Answer: alveolar hyperventilation. Notes: hypoxemia (PE, pneumonia)-->peripheral arterial chemoreceptors: neural impulses-->CNS respiratory centers-->increase respiratory drive above normal lievels-->hypocapnia. However, hypoxia continues due to underlying disease process. Increased alveolar-arterial oxygen gradient, which can be treated with oxygen & correction of the underlying disease process.

Question 50

An agent that specifically blocks the interaction of inositol triphosphate with its intracellular R would most likely decrease the activity of what?

Answer 50

Answer: PKC. Notes: - G-protein-coupled-R have 7 TM regions. G proteins are heterotrimers (alpha, beta, gamma) with GDP tightly bound to alpha subunit. - Activation=GTP replaced GDP-->alpha subunit dissociateds from beta ad gamma subunits and exposes its catalytic domain for either adenylate cycloase or phospholipase C dependong on its ligand. * DAG-->PKC; IP3-->intracellular calcium (from SR)-->PKC.

Question 51

A 34 yo man is admitted to the ICU because of fever, chills, SOB, and altered mental status. He has had these Sx for the past 1 week but has worsened over the last 24 hours. His PMH is significant for a MVA 2 years ago in which he sustained blunt abdominal trauma & required emergent laparotomy. His BP is 80/40 mmHg and pulse is 120/min. He is initiated on broad spectrum a/b, IV fluids, and vasopressors. Despite extensive resuscitative attempts, he dies 2 hours later. Blood cultures obtained on admission grow Strep Pneumo. Impairment of which of the following protective mechanisms most likely contributed to the severity of this patient's infection?

Answer 51

Answer: bacterial clearance. Notes: - -splenic rupture 2º to ab trauma 2 years ago w splenic remnants removed during laparotomy. Postsplenectomy infection. -

Question 52

An 85 yo man is transferred to the hospital from a nursing home for altered mental status & fever. Upon arrival, the patient is admitted directly to the ICU with a presumptive diagnosis of septic shock. Antibiotic therapy is initiated. The patient is unableto provide any history, but his caretakers state that he has been having non-specific symptoms, including fever for the past few days. The patient has a shistory of cardiovascular disease, diverticulitis, and dementia. His BP is 60/40 mmHg despite aggressive IV hydration. NE is administered in response to the patient's hypoT. Which cellular change occurs directly in response to NE therapy?

Answer 52

Answer: cAMP in increase in cardiac muscle cells. cAMP increases in vascular smooth muscle cells after stimulation of beta2 adrenoreceptors. NE stimulates only alpha and beta1 R. ^*Alpha1: increases IP3 - peripheral vasoconstriction, alpha2 - decrease cAMP - decrease release of NE & Insulin, beta1 - increase cAMP - increased contractility. -also note that the HR remains unchanged or even decreases afterNE admin because beta1 stimulation counteracted by indirect, baroreceptor-mediated reflexbradycardia thatoccurs following the increase in peripheral resistance.

Question 53

A 34 yo male is admitted to the hospital with acute chest pain. An ECG obtained in the ER shows ST segment elevation in leads II, II, avF. A sample of blood is taken from the patient and the plasma homocysteine level is measured 3 times using a new test. The results are 12.2 micromol/L, 13.5, and 15. These results suggest that concerns should be raised about which of the following with the new test?

Answer 53

Answer: Reliability (test-retest reliability) - repporducible. -Coefficient of variation: standard deviation/mean. %. Compares precision between tests that have diff normal values and//or diff units. *A reliabile test is reproducible in that it gives similar results on repeat measurements. Reliability is maximal when random error is minimal.

Question 54

A 67 yo caucasian male presents to your office with right tibial pain that started 3 months ago and has increased in intensity over time. His past medical history is significant for bilateral hearing impairment, diagnosed one year ago, and LT HTN. PE reveals local tenderness and a lumby protuberance over the right tibia. After extensive evaluation you proceed with bone biopsy. The pathologicst calls to tell you that there were numerous multinucleate cells in the biopsy; some cells had over 100 nuclei that were positive for tartrate-resistant acid phosphatase. Which substance is essential for the differentiation of the cells described by the pathologist?

Answer 54

Answer: macrophage colony-stimulating factor. Answer: Diagnosis=Pagets disease of the bone: older gentlemean with pain, deformity in a bony area and hearing loss - affecting tibia & skull. - a childhood infection of osteoclasts by a paramyxovirus might be responsible for paget's dsease? - osteoclasts in paget's disease are typically very large and can have up to 100 nuclei (normal osteoclasts have 2-5 nuclei). - *The 2 most important factors for osteoclastic differentiation are produced by the osteoblast: M-CSF, RANK-L - Both acidic and basic fibroblast growth factors increase bone formation by stimulation of the osteoblast. Fibroblast growth factor is also important for neovascularization for wound healing. Fracture repair. - TGF-beta increases the rep of osteoblast precursors -->increased formation of mature osteoblasts. Also increasescollagen synthesis and decreases bone resorption by increasing osteoclastic aptosis. - IGF-I increases osteoblastic replication & collagen synthesis. It also decreases collagen degradation by inhibiting the enzyme matrix metalloproteinase-13 (MMP-13). - Osteocalcin is a non-collagenous protein secreted by the osteoblast. It is used as a marker for bone formation. It is thought to limit bone mineralization.

Question 55

A 32 yo woman comes to the physician because she is worried that she will go bald. Both her father and paternal grandmotherr suffered from early-onset of baldness, but no one on the maternal side of her family is bald. PE reveals a normal appearing hairline without evidence of hair thinning. After reassuring the woman, you explain the genetics underlying the most common form of hair loss in both men and women. The most likely inheritence pattern of this condition is:

Answer 55

Answer: polygenic. Notes: - Common med conditions influenced by multiple genes: androgenetic alopecia*, epilepsy ischemic heart disease, schizophrenia, glaucoma, HTN, malignancy, T2DM. - *The mostcommon type of hair lossin males and females is known as androgenetic alopecia (male pattern baldness). - Key sites of genetic influence have been identified on the X & Y chromosomes and also on the short arm of chromosome 20. - The androgen receptor gene is located on the X chromosome so sometimes X-Linked recessive manner.

Question 56

A 32 yo woman comes to the physician because she is worried that she will go bald. Both her father and paternal grandmotherr suffered from early-onset of baldness, but no one on the maternal side of her family is bald. PE reveals a normal appearing hairline without evidence of hair thinning. After reassuring the woman, you explain the genetics underlying the most common form of hair loss in both men and women. The most likely inheritence pattern of this condition is:

Answer 56

Answer: polygenic. Notes: - Common med conditions influenced by multiple genes: androgenetic alopecia*, epilepsy ischemic heart disease, schizophrenia, glaucoma, HTN, malignancy, T2DM. - *The mostcommon type of hair lossin males and females is known as androgenetic alopecia (male pattern baldness). - Key sites of genetic influence have been identified on the X & Y chromosomes and also on the short arm of chromosome 20. - The androgen receptor gene is located on the X chromosome so sometimes X-Linked recessive manner.

Question 57

A 34 yo immigrant from Africa has patchy areas of skin anesthesia and hypopigmentation on his upper extremities. Nerve biopsy evaluated under light microscopy shows many bacteria invading Schwann cells. This patient's disease is most likely caused by what organism?

Answer 57

Answer: Mycobacterium Leprae. Answer: Leprosy (Hansen disease) is a deforming infection primarily of the skin & nerves that is caused by mycobacterium leprae. Respiratory transmission, but direct cutaneous contact has not been excluded as a mode of transmission. Armadillo. Lepromatous Leprosy: weak cell mediated TH1. Macrophages never given signal to kill mycobacterial organisms. Grows best at temps slightly lower than core body T (skin, superficial nerves, eyes, testes). CC: diffuse skin thickening, cutaneous hypopigmentation in plaques (w hair loss), leonie facies, paresis, regional anesthesia of motor & sensory nerves, testicular destruction and blindness. Tuberculoid Leprosy: intacct cell mediated immune system. Mild skin plaques - hypopigmentation, hair follicle loss, focally decreased sensation.

Question 58

A 53 yo man presents to his physician's office with a dull ache in his right shoulder. He states that his pain is worse with movement and that it often interferes with sleep. Physical examination reveals localized tenderness just below the acromion. The physician asks the patient to abduct his arms to 90 degrees and flex them to 30 degrees with his thumbs pointing to the floor. She then applies downward force to his arms. This maneuver elicits pain in the patient's right shoulder and reveals right-sided weakness as compared to the left. A tendon of which muscle is most likely inflamed in this patient?

Answer 58

Answer: supraspinatus. Notes: - The tendons of these rotator cuff muscles, along with the glenohumeral joint ligaments and the tendon of the long head of the biceps brachii muscle, contribute to the stability of the glenohumeral joint. * Of the rotator cuff structures, the tendon of the supraspinatus muscle is most commonly affected in the rotator cuff syndrome. Due to its superior location, this tendon is vulnerable to chronic repeated trauma from impingement between the head of the humerus and acromioclavicular joint. Motions that typically cause inflammation of this tendon are simultaneously abduction & flexion or trumatic fall laterally on the outstretched hand can. Inflammation is followed by fibrosis, which worsens the problem by increasing friction between the head of the humerus and the acromion, as well as causing inflammation of the subacromial bursa.

Question 59

A 34 yo immigrant from Africa has patchy areas of skin anesthesia and hypopigmentation on his upper extremities. Nerve biopsy evaluated under light microscopy shows many bacteria invading Schwann cells. This patient's disease is most likely caused by what organism?

Answer 59

Answer: Mycobacterium Leprae. Answer: Leprosy (Hansen disease) is a deforming infection primarily of the skin & nerves that is caused by mycobacterium leprae. Respiratory transmission, but direct cutaneous contact has not been excluded as a mode of transmission. Armadillo. Lepromatous Leprosy: weak cell mediated TH1. Macrophages never given signal to kill mycobacterial organisms. Grows best at temps slightly lower than core body T (skin, superficial nerves, eyes, testes). CC: diffuse skin thickening, cutaneous hypopigmentation in plaques (w hair loss), leonie facies, paresis, regional anesthesia of motor & sensory nerves, testicular destruction and blindness. Tuberculoid Leprosy: intacct cell mediated immune system. Mild skin plaques - hypopigmentation, hair follicle loss, focally decreased sensation.

Question 60

A 35 yo woman comes to ER department bc of fever & malaise for the last 4 days. History of multiple drug allergies. She admits to using heroin and cocaine regularly. CV examination reveals an early systolic murmur at left lower sternal border. MRSA - so started on IV a/b. Several days later, she complains of severe muscle pains and her serum creatinine kinase is found to be elevated. The recently administered antibiotic most likely affects which process?

Answer 60

Answer: maintenance of membrane potential. Notes: Vancomycin (D-Ala-D-Ala; red many syndrome, nepphrotoxicity) Daptomycin* (depol of cell membrane; myopathy and CPK elevation, inactivated by pulmonary surfactant; Linezolid (inhibits bacterial protein synthesis by binding to 50S; thrombocytopenia, optic neuritis, high risk for serotonin syndrome). *Daptomycin is a lipopeptide antibiotic w activity toward g+. Treats skin & skin structure infecctions & bacteremia with or without endocarditis due to S Aureus (incl MRSA). Disrupts the bacterial membrane through the creation of TM channels. -->depol of cell membrane & inhibition of macromolecular synthesis-->cell death. Can't treat pneumonias bc binds to and is inactivated by pulm surfactant.

Question 61

A 34 yo caucasian male with 2 recent episodes of exertional syncope is found to have a harsh systolic murmur on cardiac auscultation and asymmetric interventricular septum hypertrophy on echocardiography. His father died suddenly at age 30. This patient's symptoms are most likely explained by left ventricular outflow obstruction created by what?

Answer 61

Answer: mitral valve cusp & interventricular septum. Notes: Diagnosis=HCM (AD).- sarcomere proteins. -Dynamic ventricular outflow tract obstruction seen in about 25% of patients with HCM. Systolic anterior motion (SAM) of anterior leaflet of mitral valve such that it comes abnormally close to the interventricular septum as it bules into the LV outflow tract. The bulging is the result of asymmetric septal hypertrophy (ASH).

Question 62

A 64 yo woman presents to your office complaining of bleeding gums while brushing her teeth. Physical exam reveals gingival bleeding & perifollicular hemorrhages. On careful history, the patient states that she lives alone and that her diet primarily consists of tea & toast. This patient's symptoms are most likely caused by enzyme hypoactivity in which of the following compartments?

Answer 62

Answer: RER. Notes: Diagnosis: vitamin C deficiency.- malnourished (alc, poor, elderly, excessively heated foods). -Sx of scurvy - impaired formation of collagen -- gingival bleeding, petechiae, ecchymoses, perifoollicular hemorrhages, poor wound healing. *Collagen provides tensile strength to the BV wall. - Transcription of DNA for procollagen occurs in nucleus --> alpha procollagen chains are thensynthesized by RER bound ribosomes anddirectedinto the cisternae of the RER by a specific hydrophobic AA markerat theamino terminal. Hydroxylated proline & lysine. * vitamin C is a required cofactor in this posttranslational modification. [then glycosylation of lysine, to golgi after triple helix then out] cross linksformed by lysyl oxidase (covalent). - Terminal peptide cleavage (by propeptidase) of both N & C and collagen fibril crosslinking occur in ECM.

Question 63

A 65 yo male is being evaluated for fatigue, mild normocytic anemia & anorexia. He has lost 10 pounds over the last 2 months. CXR reveals an irregular perihilar mass in the right lung field. This patient's symptoms can be mimicked in experimental animals by administration of which cytokine?

Answer 63

Answer: TNF-alpha. Notes: -TNF-alpha is produced by macrophages in response to infection as well as by some neoplastic cells. Its role in cachexia is explained by its influence on hypothalamus-->appetite suppression: suppress appetite, inhibit lipoprotein lipase, increase insulin R of peripheral tissues. Production of fever, IL-1, septic shock symptoms, hepatic release of acute-phase reactiants (C-reactive protein, fibrinogen).

Question 64

A protein believed to play a role in signal transduction & the cellular response to TSH is studied. Special attention is paid to a region of this protein that contains several alpha-helical regions each composed of approximately 20 AA residues - consisting primarily of valine, alanine, and isoleucine. Which function does this region most likely form?

Answer 64

Answer: spanning the cellular membrane. Notes: - Non-polar, hydrophobic AA such as valine, alanine, isoleucine, methionine, and phenylalanine are generally located interiorly on globular proteins, where they are shielded from direct contact with water. - The classic PM-spanning proteins are executors for glycoprotein hormones, such as TSH, LH, and FSH. These G-protein-coupled membrane-bound R for glycoprotein hormones contain 3 major domains: extracellular (ligand binding), TM (hydrophobic), intracellular (coupled w G-proteins).

Question 65

A mouse is fed with food that is rich in nitrates. As a result, the chromosomal DNA of the intestinal epithelial cells undergoes accelerated cytosine deamination. What is the correct order of enzymes that repair the damage?

Answer 65

Answer: Glycosylase, endonuclease, lyase, DNA polymerase, ligase. Notes: Base exceision repair is used to correct defects in single bases induced spontaneously or by exogenous chemicals. -Nitrates consumed in the diet-->deamination: cytosin-->uracil, adenine-->xanthine, guanine-->hypoxanthine. ^These resulting bases are not normally present in DNA & recognized by specific glycosylases, which cleave these altered DNA bases from the parent DNA molec-->empty sugar-phosphate site basic site=apurinic-apyrimidinic site. =>endonuclease then cleaves the 5' end of the AP sit before a lyase enzyme subsequently completes the removal of the AP site from the DNA molecule by removing the sugar phosphate group. =>DNA poly fillls gap with correct sugar-phosphate-base=>joined to strand by ligase.

Question 66

A 34 yo male diagnosed with acute myelogenous leukemia recently underwent successful induction chemotherapy with doxorubicin. Several weeks later, he presents to your office complaining of progressive dyspnea & orthopnea. What is most likely responsible for the patient's symptoms?

Answer 66

Answer: Dilated cardiomyopathy. - Notes: The anthracyclines (daunorubicin, doxorubicin, epirubicin, idarubicin) are chemotherapeutic agents associated with severe cardiotoxicity (cumulative dose-related dilated cardiomyopathy) due to free radical generation. * Presents many mo after d/c of drug. Swelling of SR is morphologic sign of an early stage-->loss of cardiomyocytes 9"myofibrillar dropout") - Sx: biventricular CHF = dyspnea on exertion, orthopnea, peripheral edema. * **The most effective method of preventing doxorubicin cardiomyopathy is dexrazoxane an iron-chelating agent that decreases formation of oxygen free radicals by doxorubicin and other anthracyclines.

Question 67

A 67 yo man admitted for right lower lobe pneumonia subsequently develops hypoT and lactic acidosis. He is started on a NE intravenous dip. A few hours later, the antecubital vein being used for the infusion blanches and the tissues surrounding the IV site become cold, hard, and pale. Local injection of the affected tissues with which of the following agents is most likely to be of greatest benefit?

Answer 67

Answer: phentolamine. Notes: -Diagnosis=NE extravasation. - vasoconstriction can lead to local tissue necrosis.

Question 68

A 65 yo man comes to the physician complaining of progressive weight loss, jaundice, and anorexia for the last 3 months. He notes that his urine has been dark and his stools have been pale. On physical examination, his gallbladder is found to be enlarged but nontender. Which of the following is the most important RF predisposing to this patient's condition?

Answer 68

Answer: smoking. Notes: Diagnosis=adenocarcinoma at the head of the pancreas compressing the common bile duct --> palpable but nontender gallbladder (courvoisier sign), weight loss, obstructive jaundice (pruritis, dark urine, pale stools). -Cancers of body & tail of pancreas don't produce Sx until invasion of the splanchnic plexus and cause midepigastric abdominal pain. * Age: highest incidence 65-75. * Genetic predisposition - hereditary pancreatitis, MEN, HNPCC, FAP syndromes...

Question 69

A 43 yo male complains of a dry cough and recent weight loss. Transbronchial biopsy of a lung mass IDd on CT scan demonstrates large cells with prominent nucleoli. The latter finding is best explained by a high activity on what?

Answer 69

Answer: RNA polymerase I. Notes: -Nucleolus is ar round dense body in the nucleus comprosed of proteins, ribosomal DNA (DNA that encodes ribosomal RNA), and rRNA - basophilic - production/maturation of ribosomes. -RNA I: ribosomal RNA in nucleolus from DNA. -RNA poly II-->mRNA, snRNPs. RNA poly III - tRNA - like RNA I requires very few regulatory factors.

Question 70

After emerging from a "smoke" in the men's room at a bar, a 27 yo male becomes agitated and belligerent. He displays intermittent clonic jerking of his extremities and assaults a bouncer who tries to calm him. Intoxication with which substance is most likely?

Answer 70

Answer: phencyclidine (PCP) Notes: -Among drugs of abuse, intoxication with hallucinogens i(psychotomimetic drugs), amphetamines, and cocaine most associated with violent behaviors. Hallucinogens include LSD, PCP (angel dust), and mescaline. Whereas LSD can cause aggressive behavior, it is more typically characterized by affective lability, thought disruption (delusions) and visual hallucinations. PCP tends to produce more belligerence behavior and psychomotor agitation including clonic jerking of extremities. It's often sprinkled onto a marijuana cigarette.

Question 71

Elastin fibers in alveolar walls of the lungs can be stretched easily during inspiration and recoil to their original shape once the force is released. The process facilitates expiration. Explanation of this property?

Answer 71

Answer: interchain crosslinks involving lysine. Notes: - Elastin is primiarly composed of nonpolar AA glycine, alanine, valine + proline & lysin. However, in contrast tocollagen, few are hydroxylated. - tropoelastin to ECM to interact with fibrillin - some Lysine residues covalently bound to form a desmosine x-link. Extensive desmosine x-linking accounts for elastin's resilient properties.

Question 72

A 21 yo caucasian male has asthma that is not adequately controlled with occasional (PRN) albuterol. You decide to start him on aerosol flunisolide therapy. The patient should be instructed to what?

Answer 72

Answer: oral rinsing. NOtes: Inhaled glucocorticoids most commonly used prophylactic therapy for patients with persistent bronchial asthma. 1) prevention of Sx. 2) maintenance of near-normal pulm function. 3) maintenance of normal activity levels. *The most common side effect of inhaled glucocortioids is oropharyneal candidiasis. Use a spacer and rinse mouth. Dysphonia due to myopathy of laryngeal muscles too?

Question 73

A 57 year old male with suspected bacterial pneumonia is admitted to the hospital and given ceftriaxone and azithromycin for treatment. Soon after the first dose of ceftriaxone he complains of difficulty breathing, abdominal cramps, and lightheadedness. His current BP is 70/50 mmHg, while his heart rate is 120/min. PE reveals a diffuse maculopapular rash. Which drug should be administered next?

Answer 73

Answer: epinephrine. Notes: Diagnosis=anaphylactic shock. * Epi is drug of treatment of anahhylactic shock due to reverse all of pathophysiologic mechanisms: - stim of alpha1 R counteracts vasodilation -->increase BP; increases cardiac contractility & CO (beat1); beta2-->bronchodilation!!!

Question 74

A 76 yo man comes to the physician complaining of progressive lower back pain for the past 2 mo. He describes the pain as constant and nagging. It is especially bad at night, interfering with his sleep. THe pain is not relieved by rest or position changes. He also complains of urinary urgency, nocturia, frequency, and hesitancy. His past medical history is significant only for HTN. Which process is most likely responsible for this patient's back pain?

Answer 74

Answer: neoplastic. Notes: *Back pain not relieved by rest or position change is a typical presentation for neoplastic bone disease. The combination of symptoms of urinary urgency, nocturia, frequency and hesitancy with constant back pain in an elderly man together suggests prostate cancer.

Question 75

A 12 yo male bleeds from his mouth after a tooth extraction. The bleeding lasts for more than 12 hours despite local application of thrombotic agents. The bleeding finaly stops after desmopressin admin. The patient has no past medical history & takes no meds. His last physical exam with his pediatrician was unremarkable. Which most likely explains the moa of the drug on this patient?

Answer 75

Answer: increase in endothelial protein release. Notes: Diagnosis: mild form of vWF disease (no major sp bleedingg). * DDAVP increases vWF release from endothelial cells. - After injection of DDAVP, vWF levels increase in 30-60 minutes. DDAVP not beneficial in severe disease when there is almost complete deficiency of vWF. * Rememer that desmopressin tablets can also used for treatment of enuresis.

Question 76

A 5 yo male with a bounding pulse has a thrill best palpated over the upper left sternal edge. A continuous murmur is heard over the area on cardiac auscultation. If surgery is planned, the surgeon should intervene on a derivative of which of the following embryologic structures?

Answer 76

Answer: 6th aortic arch. Notes: Diagnosis=PDA. * The 6th aortic arch gives rise to the pulmonary arteries & ductus arteriosus. * open PDA required L-->R shunt as in tetralogy of fallot & transposition. - Sinus venosus - smooth portion of RA - sinus venarum. - Bulbus cordis - beginning of the ventricular outflow tract in embryonic heart - smooth portion sof LV & RV adjacent to aorta & pulmonary artery respectively. - the primitive atrium forms the rough portions of the LA & RA.

Question 77

A 78 yo caucasian male presents for a routine check-up. His BP is 180/70 mmHg and his HR is 75 bpm. PE findings are within normal limits. You explain to the patient that his HTN is most likely caused by age-related what?

Answer 77

Answer: aortic stiffening. Notes: -SBP>140/90, the cuoff for the diagnosis of HTN & initiation of antihypertensive therapy. However, the patient's diastolic BP is within normal range. After age 50, the pattern of isolated Systolic HTN common (>160,

Question 78

A 32 yo caucasian female presents to your office with a breast mass found to be malignant on biopsy. 10 years ago, she was diagnosed with osteosarcoma and underwent right lower limb amputation. Her mother died of a brain tumor at age 35 and her aunt suffered from rhabdomyosarcoma. Which gene ?

Answer 78

Answer: p53. Notes: Diagnosis=Li-Fraumeni syndrome. - predisposed to early development of cancr. p53, AD. * Normally, p53 causes cells with mutant DNA to arrest in G1/S stage of cell cycle until the damage is repaired. - Li-Fraumeni inherit 1 mutatedallele of p53, somatic mutation of the 2nd allele is needed for tumor development. Malignant tumors at young age (

Question 79

A 63 yo man with a history of chronic obstructive pulmonary disease comes to the physician for a f/u visit. He uses tiotropium inhaler daily and his pulmonary symptoms are sufficiently controlled. During a previous visit, he was counseled on the benefits of smoking cessation. He reports that despite trying he has been unable to stop smoking due to overwhelming cravings. The physician prescribes a drug that reduces nicotine cravings while decreasing the pleasurable effects of cigarettes and other tobacco products. What drug was most likely prescribed to the patient?

Answer 79

Answer: varenicline. Notes: - partial stimulator at alpha4beta2 nicotinic acetylcholine receptor (competitive antagonist) - reduces nicotine withdrawal, prevents nicotine from binding and inducing reward response. * Varencicline's partial agonist activity only causes limited downstream release ofDA=less stim of reward pathways than nicotine.

Question 80

A 35 yo female presents to the ER with a "racing heart" and SOB. She also admits to insomnia. Cardiomegaly is noted on CXR. An EKG shows sinus tachycardia at 120 bpm. Serum TSH is decreased and free T4 is increased. IV propanolol is given to this patient. In addition to its beta R blocking actions, propranolol is likely to benefit this patient by decreasing what?

Answer 80

Answer: peripheral conversion of T4 to T3. Notes: -NB: IPODATE also does this.

Question 81

A 22 yo caucasian male with fever & joint pain is found to have atypical lymphocytes on his blood smear. This patient's symptoms are caused by an enveloped virus having partially ds circular DNA. An enzyme packed in its virion has RNA-dependent DNA-polymerase activity. This patient is most likely infected with what?

Answer 81

Answer: Hepatitis B Virus. Notes: The hep B virus genome consists of partially ds circular DNA. Replication is accomplished through a reverse transcriptase DNA polymerase that creates an intermediate + ssRNA template and ds DNA progeny.

Question 82

Dividing g- bacteria are isolated from the urine of a 34 yo female with dysuria. The organisms are noted to incorporate uracil into their DNA molecules during replication. This finding is mediated by which enzyme?

Answer 82

Answer: primase. * In general, uracil is found only in RNA, so the question essentially asks which enzyme would incorporate RNA into a DNA strand. * Primase is a DNA-dependent RNA polymerase that incorporates short RNA primers into replicating DNA.

Question 83

A 16 yo girl comes to the physician complaining of pelvic pain. She says that she develops crampy lower abdominal pain every 28 days that resolves in a day or two. She states that she has never had a menstrual period. The patient is at the 60th percentile for height, 70th percentile for weight, and has fully developed secondary sexual characteristics. Rectal examination reveals a palpable mass anterior to the rectum. Serum beta-hCG is negative. Which of the following is the most likely diagnosis in this patient?

Answer 83

Answer: imperforate hymen. Notes: Absent menses in the context of normal ovarian & anterior pituitary gland function is termed "eugonadotropic amenorrhea."" Primary amenorrhea in a a pt w fully developed secondary sexual characteristics suggests the presence of an anatomic defect in thegenital tract, most commonly an imperforate hymen or a mullerian duct anomaly. -An imperforate hymen is one of the mos common obstructive lesions of the female genital tract. At birth, vvaginal secretions stimulated by the mom's E levels can cause mucocolpos - bulging introitus. @ menarche, history of cyclic abdominal or pelvic pain (hematocolpos) - can also cause back pain & difficulties with defecation and urination. On examination, hematocolpos manifests as a vaginal bulge &/or mass palpated anterior to the rectum. - The main RF for ectopic pregnancy is history of PID. - patients with testicular feminization syndrome (complete androgen insensitivity) have normal breast evelopment but sparse pubic & axillary hair development. There will be absent wolffian andmullerian structures. - Turner syndrome (karyotype 45,XO) is a common cause of primary amenorrhea. Affected individuals have short stature, webbed neck, shielded chest, fibrotic ovaries. They don't develop secondary sexual characteristics.

Question 84

A 54 yo known alcoholic male is brought to the ED by his wife because of several episodes of vomiting bright red blood. He is admitted to the hospital, and by the following morning, he is disoriented and does not know the year or his location. Physical examination shows abdominal distention, flapping tremor, and gynecomastia. Liver span is decreased. What is the most likely precipitant of his altered mental status?

Answer 84

Answer: increased load of nitrogenous substances absorbed in the gut. Notes: Diagnosis=hepatic encephaopathy. *precipitated by his hematemesis - GI bleed-->increased ammonia and nitrogen absorption in gut (as does chronic infection --> tissue injury/hemolytic anemia). ^: stressor that alters amonia balance (hypovolemia, hypokalemia/diuretics!!!, metabolic alkalosis, hypoxia, sedative usage - exacerbates since ammonia crosses BBB-->stimulates GABA, hypoglycemia*, infection^).

Question 85

A 62 yo caucasian male is brought to your office by his daughter. The daughter says that her father has been acting strangely over the last year. She says that he makes inappropriate jokes, is irritable, and is even aggressive at times. In speaking with the patient, you notice dysarthria. This patient most likely has a condition involving what part of the brain?

Answer 85

Answer: Frontal Cortex. Notes: -Frontal lobe: motor cortex, Broca's speech area, frontal eye fields, prefrontal cortex. *Lesions of prefrontal cortex cause inappropriate behavior, impaired judgment, lost problem-solving skills. Incontinence & gait disturbances. Diagnosis=Pick's disease. - progressive dementia, behavioral disinhibition, speech difficulties (dysarthria, aphasia, echolalia).

Question 86

A 65 yo male taking amoxicillin for sinusitis is hospitalized with diarrhea and abdominal cramps. CBC shows leukocytosis. The toxin responsible for his current condition primarily damages which components of intestinal mucosal cells?

Answer 86

Answer: cytoskeleton integrity (see notes).

Question 87

A 30 yo man with a history of IVDU and known HIV infection comes to the ED bc of increasing abdominal distention and anorexia. A CT scan of the abdomen shows ascites and a large mass surrounding the small intestine. Bx of the mass reveals uniform, round, medium-sized tumor cells w basophilic cytoplasm and a proliferation fraction (Ki-67 fraction) of >99%. Which infection?

Answer 87

Answer: EBV. Notes: * The EBV genome is identified in approximately 50% of systemic B-cell lymphomas and almost all primary CNS lymphomas occuring in the setting of HIV infection. * A high mitotic index is typical of Burkitt lymphoma. - Burkitt Lymphoma: t(8;14) - overexpression of c-myc ( a transcriptional regulator that controls cell proliferation) - diffuse medium-sized lymphocytes & high prolif index prrepresented by high Ki-67 fraction approaching 100%.

Question 88

A 22 yo male presents to your office complaining of occasional h/a. On exam you note several pigmented spots on his trunk. You also discover a few rubbery cutaneous tumors on his neck. The cells composing these skin tumors most likely originated from which of the following structures?

Answer 88

Answer: Neural crest. Notes: Diagnosis=cafe-au-lai macules=pigmented lesions. H/a to glioma? -Neurofibromas are tumors of schwanna cells (neural crest)* - skin colored or pink nodules. Rubbery texture - "buttonhole".

Question 89

A new drug that is used to treat HTN ER causes arteriolar dilation. It also increases renal perfusion and promotes natriuresis. The drug described is most similar with what drug?

Answer 89

Answer: Fenoldopam. Notes: *Fenoldopam: selective DA-1 R agonist with no effect on alpha or beta R - stimulates adenylyl cyclase and raises intracellular cAMP-->vasodilation of most arterial beds, esp renal, mesenteric, and coronary. Stim of DA R in kidneys not only improves renal BF but also leads to increased sodium and water excretion. ^CC: short term management of severe HTN...good for concomitant renal insufficiency.

Question 90

The autopsy of a 78 year old caucasian male who died of esophageal cancer reveals a small heart without significant coronary artery atherosclerosis. Myocardial cells show prominent intracytoplasmic granules that are tinged yellowish-brown. Which most likely accounts for the observed microscopic changes?

Answer 90

Answer: lipid peroxidation. Notes: Lipofuscin=insoluble pigment composed of lipid polymers & protein-complexed phospholipids. It is the product of free radical injury & lipid peroxidation commonly seen in the heart & liver of aging or cachetic, malnourished pts.

Question 91

The autopsy of a 78 year old caucasian male who died of esophageal cancer reveals a small heart without significant coronary artery atherosclerosis. Myocardial cells show prominent intracytoplasmic granules that are tinged yellowish-brown. Which most likely accounts for the observed microscopic changes?

Answer 91

Answer: lipid peroxidation. Notes: Lipofuscin=insoluble pigment composed of lipid polymers & protein-complexed phospholipids. It is the product of free radical injury & lipid peroxidation commonly seen in the heart & liver of aging or cachetic, malnourished pts.

Question 92

Esophageal manometric studies performed on a 38 yo caucasian male demonstrate periodic, non-peristaltic contractions of a large amplitude & long duration. Clinical manifestations of this patient's condition would most closely mimic which of the following?

Answer 92

Answer: angina pectoris. Notes: -Diffuse esophaeal spasm. Usually coordinatied. In DES,several segments of the esophagus contract at the same time, which prevents the propagation of the food bolus toward the stomach...painful. "corkscrew" esophagus. *Symptoms of DES areintermittent dysphagia & occasional chest pain. In typical cases, the chest pain is not associated with exertion and is not relieved by rest...sometimes, however, the pain may mimic unstable angina in intensity and location!!!

Question 93

A new medication with a wide spectrum of antibacterial activity has been synthesized. It is an analog of D-ala-D-Ala that blocks bacterial peptidoglycan cross-linking. It is also resistant to degradation by acterial enzymes. Which bacteria is most likely to be resistant to this new drug?

Answer 93

Answer: mycoplasma hominis. Notes: *organisms in the mycoplasma genus, including ureaplasma urealyticum, lack peptidoglycan walls. -Drugs that are effective against hte mycoplasma genus include anti-robosomal agents like the macrolides & tetracyclines.

Question 94

A 32 yo female comes to your office for evaluation of infertility. She reveals that her menstrual periods occur 2-3 times per year. Physical examination reveals moderate obesity and excessive facial hair growth. This patient is at increased risk for which condition?

Answer 94

Answer: endometrial adenocarcionma. Notes: Diagnosis=PCOS: obesity + hirsutism + oligomenorrhea. Abnormality of HPOvarian system. Elevated androgen and LH, but normal FSH. An increase LH/FSH>3 is characteristic. Tendency toward insulin resistance and lipid profile abnormalities too.

Question 95

A 34 yo presents to the ED with a high fever, chills, and a cough productive of "greenish" sputum. He admits to heavy alcohol use recently. On physical exam, there are crackles over his right lower lung lobe. What accounts for the color of this patient's sputum?

Answer 95

Answer: myeloperoxidase. Notes: myeloperoxidase is a blue-green heme-based pigment molecule contained within the azurophilic granules of neutrophils that catalyzes the production of HOCl from Cl- & H2O2 during the phagocytic respiratory burst.

Question 96

A 65 yo (f) with ovarian cancer is being reated with cisplatin-based chemotherapy. Which of the following prophylactic measures would most likely limit the toxicity associated with this chemotherapy regimen?

Answer 96

Answer: amifostine. Notes: Cisplatin is a platinum-containing compound - reactive oxygen species that can form DNA crosslinks. Acute tubular injury. * Amifostine is a thiol-based cytoprotective freeradical scavenging agent used to decrease the cumulative nephrotoxicty associated with platinum containing agents, therey disallowing reaction with the renal tubules. * Another preventive measure is establishing a chloride diuresis (via IV normal saline) bc cisplatin stays in a nonreactive state when in a higher chloride concentration. NB: Dexrazoxane is an iron-chelating agent that can help prevent anthracycline-induced (ie - doxorubicin) cardiotoxicity (CHF).

Question 97

HCV strains isolated from a single individual demonstrates significant variability. This genetic instability of HCV is attributed in large part to its RNA-dependent RNA polymerase, which lacks:?

Answer 97

Answer: 3'-->5' exonucletase activity. Notes: -encoding of its 2 envelope glycoproteins - hypervariable region prone to mutation - no proofreading 3'-->5' exonuclease activity built into the virion-encoded RNA polymerase!

Question 98

A 36 yo woman complains of dyspnea and weakness. Her mother had similar symptoms and died at 42 years of age. After an extensive work-up, a lung biopsy was performed that showed decreased intraluminal diameter of smallbranches of pulmonary artery &medial hypertrophy. Thepatient was subsequently shceduled for a lung transplant. Which of the following meds is indicated for her management during the waiting period?

Answer 98

Answer: Bosentan. Notes: the patient described has characteristic histo findingsof pulmonary hypertension, but no underlying lung or heart disease. Herfamily history sugests that she has aninherited form ofprimary pulmonary hypertension: decreased apoptosis ofendothelial & smooth musclecells in pulmonary arterioles(f, 20-40 yr, dyspnea + exercise intolerance). *Although lung transplant is the ultimatetreatmentof this disease, vasodilatorshave been effective for improving symptoms. Bosentan is an oral endothelinreceptor antagonist recently approved for treatment of pulmonary HTN. (Endothelin - vasoconstrictor, endothelial prolif).

Question 99

A 53 yo woman presents to your office for routine check-up. She has no present complaints. Her past medical history is significant for osteoarthritis of the R knee. Her mother suffered from HTN and was diagnosed with breast cancer at 68 years old, which caused the woman's death 4 years later. The patient's father had diabetes mellitus and died in a motor accident. Today's blood pressure is 140/85 mmHg, and HR is 80/min. Physical examination, includingbreast examination, is normal. Laboratory testing is significant for a blood glucose level of 160 mg/dL. This patient will most likely die of what cause?

Answer 99

Answer: MI. Notes: CV moraity is increased by 2-3 fold in patients w DM, even in the absence of other major risk factors for ischemic heart disease such as HTN, hypercholesterolemia, and smoking. *For a person w DM, the risk of dying from ischemic heart disease exceeds the risk of DYING from any other lists. Leading cause of ESRD then HTN but more than 50% of pts w ESRD die due to ischemic heart disease.

Question 100

A 34 yo male with a squamous cell carcinoma undergoes surgical neck dissection. While attempting to ligate the inferior thyroid artery, the surgeon accidentally damages a nerve that lies in close proximity to it. Which of the following nerves was most likely damaged?

Answer 100

Answer: Recurrent laryngeal nerve. Notes: The inferior thyroid artery arises from the thyrocerical trunk, a branch of the subclavian artery. Along with the superior thyroid arteries (branches of external carotid arteries), the inferior thyroid arteries provide blood to thyroid gland and other structures of anterior neck. -Courses deep to vagus n, common carotid artery, internal jugular vein before turning toward thyroid. Courses just superficial to recurrent laryngeal nerve (branch of vagus that loops below aortic arch on L & below subclavian artery on R) to provide motor innervation to muscles of larynx (all except cricothyroid). Unilateral injury to this nerve-->hoarse, iblat-->resp difficulty due to airway obstruction by imobile vocal cords.

Question 101

A 53 yo woman presents to your office for routine check-up. She has no present complaints. Her past medical history is significant for osteoarthritis of the R knee. Her mother suffered from HTN and was diagnosed with breast cancer at 68 years old, which caused the woman's death 4 years later. The patient's father had diabetes mellitus and died in a motor accident. Today's blood pressure is 140/85 mmHg, and HR is 80/min. Physical examination, includingbreast examination, is normal. Laboratory testing is significant for a blood glucose level of 160 mg/dL. This patient will most likely die of what cause?

Answer 101

Answer: MI. Notes: CV moraity is increased by 2-3 fold in patients w DM, even in the absence of other major risk factors for ischemic heart disease such as HTN, hypercholesterolemia, and smoking. *For a person w DM, the risk of dying from ischemic heart disease exceeds the risk of DYING from any other lists. Leading cause of ESRD then HTN but more than 50% of pts w ESRD die due to ischemic heart disease.

Question 102

A 46 yo caucasian female with severe upper abdominal pain, vomiting, and fever is found to have an inflamed and partially necrotic gallbladder on laparotomy. Which of the following events most likely initiated this patient's condition?

Answer 102

Anwer: gallbladder outflow obstruction. Notes: Diagnosis: acute calculous cholecystitis (ACC) is characterized by acute inflammation of the gallbladder, initiated 90% of the time by obstructin of the gallbladder neck or cystic duct. Typically from chemical irritationand inflammation caused by presence of stones. Disrupt the protective mucus layer. PGs released by gallbladder further incite inflammation of mucosa & deeper tissues-->gallbladder hypomotility. The increasing distention & internal pressure within the gallbladder eventually result in ischemia.

Question 103

A new drug has been developed that inhibits one of the steps in fatty oxidation. It is considered promising for the treatment of stable angina. Which of the following is the most likely mechanism explaining the potentially beneficial effect of the drug in patients with this condition?

Answer 103

Answer: less oxygen use per one ATP synthesized. Notes: - E for myocardial cellular function is produced from 3 major sources: glycolysis, glucose oxidation, FA oxidation. - Although FA oxidation results in greater AP production, it requires more oxygen use in comparison to glucose utilization and glycolysis. Despite this, FA oxidation is the main source of E production (60%) while glucose oxidation (30%) & glycolysis (5%). * In stable angina, atherosclerosis leads to reduced oxygen delivery to cardiac mitochondria-->since glucose oxidation requires less oxygen, it is believed that shifting energy production from FA oxidation to glucose oxidation may be more oxygen efficient and beneficial in treating angina.

Question 104

A 40 yo female presented to the physician for evaluation of worsening fatigue. She has no other medical problems. She does not use tobacco, alcohol, or drugs. Vital signs are within normal limits. Physical exam is within normal limits. Lab eval shows an alkaline phosphatase level of 180 U/L. W What should be checked next?

Answer 104

Answer: gamma-glutamyl transpeptidase. - biliary tract with alkaline phosphatase. * alkaline phosphatase threefold elevation relatively nonspecific - especially in hepatocytes & bone. Gamma tlutamyl transpeptidase also extrahepatic tissues but not really in one so good in determining whether an elevated alkaline phosphatase is of hepatc or bony origin.

Question 105

A 40 yo female experiences a right knee injury during routine sport activities. She is treated with an opioid analgesic in ER & her knee pain decreases significantly. However, soon after the analgesic administration she complains of severe abdominal pan that makes impossible for her to lie still. Physical examination reveals tenderness over the right upper abdominal quadrant. A drug effect on what structure is most likely responsible for this patient's current condition?

Answer 105

Answer: smooth muscle cells. Notes: mu opioid analgesics contract smooth muscle cells in the sphincter of Oddi-->costriction and spasm. Increass common bile duct pressures. *Meperidine is believed to cause less sphincter of Oddi constriction and is often considered the opioid of choice in biliary and pancreatic pain. - all mu opioids cause histamine release --> vasodilation of blood vessels and itching. - all usually decrease parietal cell acid secretion.

Question 106

A 66 year old man with a recently-discovered lung mass develops dizziness, dysarthria, and limb ataxia worsening over the past 2 weeks. He denies other medical conditions and takes no medications. He has smoked 1 pack per day for the past 50 years and denies alcohol or illicit drug use. He is admitted to the hospital for evaluation but develops worsening neurological symptoms. Despite appropriate medical therapy, he dies 2 weeks later. Autopsy shows extensive cerebellar purkinje cell degeneration. What best describes the etiology of this patient's neurologic condition?

Answer 106

Answer: Autoimmune. Notes: -paraneoplastic syndromes are often caused by substances produced from tumor cells that induce an autoimmune phenomenom, with the antibodies produced against the tumor cells x-reacting with the body's own healthy organs & tissues. paraneoplastic cerebellar degen is a type of paraneoplastic syndrome most commonly associated with cancers of the lung (anti-P/Q), breast (anti-Yo) - also seen with ovary, uterus, and lymphoma. Anti-Hu also lung. These AB react against (also uterus and lymphoma) react against tumor cells x-react w neurons-->degen of cerebellum - limb and truncal ataxia, lack of coordination, dysarthria,nystagmus.

Question 107

A 57 yo caucasian male with severe pyelonephritis is admitted to the hospital. His past med history is significant for diabetes, hypertension, and 2 episodes of transient ischemic attacks. his serum creatinine level is 3.2 mg/dL. Therefore, he needs to be started on an a/b that depends mainly on non-renal clearance. What characteristic should the a/b also have if hepatic metabolism & clearance is desired.

Answer 107

Answer: High lipophilicity. Notes: Drugs wit high intrinsic hepatic clearance tend to have high lipophilicity and high volume of distribution. Poorlyeliminated by kidney if highly lipophilic bc rapidly cross tubular membranes after filtration to reenter the tissues. Allows to enter hepatocytes --> excreted in bile or through other methods of elimination. -low Vd highly plasma protein-bound and hydrophilic, making it less available for hepatic metabolism and more readily available for excretion unchanged in urine. - *lipophlic=high Vd=good penetration into CNS = liver-->more polar compounds for easier elimination in bile & urine.

Question 108

A 65 yo caucasian male admitted following an acute ST-segment elevation MI experiences chest pain on day 4 of his hospitalization. He describes the pain as sharp in quality, and adds that it increases with coughing and swallowing and radiates to his neck. The BP is 130/80 mmHg, pulse is 90 bpm, T is 101F and resp are 20/min. What is the most likely cause of patient's chest pain?

Answer 108

Answer: pericardial inflammation overlyng the necrotic segment of myocardium. Notes: - pericardial involvement due to sharp pleuritic naure. - exacerbation with swallowingindicates posterior pericardium, radiation into neck suggests involvement of inferior pericardium, which is adjacent to phrenic nerve afferents uspplying hte diaphragm* - low-grade fever=inflammatory process! *A fibrinous or serofibrinous early -onset pericarditis develops between days 2-4 in transmural MI...1-3 days of ASA treats it.

Question 109

A 34 yo man is being followed by his pulmonologist for management of bronchial asthma. The patient has had asthma since childhood and states that he is "a regular visitor of the emergency room." After repeated asthma exacerbations and failed treatments, the physician prescribes him prednisone. The frequency and severity of his attacks decrease as a result of this treatment. Which tissue is most likely to increase protein synthesis in response to this therapy?

Answer 109

Answer: liver. Notes: * Glucocorticoids-->liver gluconeogenesis: PEP carboxykinase, glucose-6-phosphatase. * Overall glucocorticoids inhibit RNA & protein syntehsis in many tissues such as muscle, however, hepatic RNA & Protein synthesis are stimulated.