UWorld QBank - 2nd round - part 4 Flashcards
(144 cards)
What would you see on biopsy with a thyroid papillary carcinoma?
- Large cells w/ overlapping nuclei containing finely dispersed chromatin -> ground glass appearance (orphan annie eyes)
- Numerous intranuclear inclusions and grooves
- Psammoma bodies
Which reaction in the TCA requires thiamine?
alpha ketoglutarate -> succinyl CoA which uses alpha-ketoglutarate dehydrogenase complex
(Note: pyruvate dehydrogenase also requires, but this is not part of TCA, b/c it forms acetyl CoA which then combines w/ OAA -> citrate)
How is aortic regurgitation murmur best heard?
Early diastolic, high-pitched blowing decrescendo murmur, best heard at L sternal border, w/ patient leaning forward (brings valve closer to chest wall) and at end expiration (most left sided heart sounds heard better at end expiration)
How would the cardiac cath blood pressure curve appear for someone w/ aortic regurgitation?
High peaking LV and aortic pressures during systole (because increased blood volume in LV) and a steep diastolic decline of aortic pressure (because regurgitation)
How is Isoniazid metabolized? What would cause high levels of Isoniazid for a longer period of time?
acetylation in hepatic microsomal system by enzyme n-acetyl transferase -> excreted in urine
Slow acetylators of isonaizid will take longer to metabolize.
A young patient presents w/ recurrent bouts of acute pancreatitis. HIs ultrasound is normal, he has no other known medical problems, takes no medication, and does not consume alcohol. What is most likely the cause? What is usually the major cause for this?
Hypertriglyceridemia -> excess free fatty acids cannot all be bound up by albumin -> direct injury to pancreatic acinar cells
Usually gallstones and alcoholism are the main causes but if these and structural, genetic abnormalities are ruled out one should consider hypertrigs.
What would you see on biopsy in medullary carcinoma of the thyroid?
Nests of uniform polygonal or spindle shaped cells w/ extracellular amyloid deposits which stain positively for congo red -> originate from parafollicular calcitonin secreting C-Cells
What is the appearance of follicular adenoma/carcinoma of the thyroid on biopsy?
FA: Sheets of uniform cells forming colloid containing microfollicles
FC: would have similar findings (and even more closely resembling thryoid tissue) w/ capsular and vascular invasion
Why are patients w/ ataxia-telangiectasia predisposed to infections?
IgA deficiency predisposes to frequent infections of upper and lower airways
How would a patient w/ pantothenic acid deficiency present?
Rare condition of low Coenzyme A -> usually in severely malnourished -> paresthesias, dysesthesias (burning feet syndrome), and GI distress
What happens to someone who is deficient in CD55 and CD59? What is this disorder associated with?
Paroxysmal Nocturnal Hemoglobinuria (PNH) -> complement mediated hemolysis from a deficiency in synthesis of glycosylphosphatidylinositol (GPI) anchor necessary for attachment of CD55 (decay accelerating factor) and CD59 (MAC inhibitory protein) - both of these protect from complement attack.
Often associated w/ budd chiari syndrome, pancytopenia and aplastic anemia
What drugs are likely to cause drug induced lupus? How are they metabolized?
Hydralazine and Procainamide -> metabolized by acetylation in liver then renal excretion -> slow acetylators may be more prone to develop lupus like effects (Dapsone and Isoniazid are also metabolized by acetylation)
What is the MoA of dobutamine?
beta-agonist -> mainly on B1 w/ some activity on B2 and A1
B1 stimulation -> increased cAMP -> positive ionotrope effect (increased contractility) & weakly positive chronotrope (increased heart rate) & increased cardiac conduction velocities
Which factors can predispose patients to first dose hypotension w/ ACEI therapy? Which drugs should be watched out for?
Hyponatremia, hypovolemia (secondary to diuretic therapy), low baseline blood pressure, high renin/aldosterone, renal impairment, and heart failure.
Thiazide/Loop diuretics can cause hypoNa+ and hypH2O
What is another term for precision?
Reliability
What secondary cell signaling molecule is responsible for activating Raf kinase in a growth factor messenger pathway that includes Tyrosine kinase and SOS protein and MAP kinase downstream?
GTP as part of the Ras (G-Protein) system in the Ras-MAP Kinase signaling pathway
What opportunistic infections should be looked out for in HIV+ patients w/ CD4 counts
Mycobacterium avium complex (M avium & M intracellulare) - grows at 41 C
Prophylaxis w/ Azithromycin b/c it is resistant to most typical antibacterial drugs
Which symptoms of opioid use are usually not affected by increased tolerance to the drug?
Constipation (because this is a result of direct stimulation of Mu-R in the GI tract by opioid) and Miosis (b/c this caused by opioid activation of PANS innervation on the pupil)
How quickly will loss of myocardial contractility occur upon total myocardial ischemia during a heart attack? When will irreversible injury occur?
Loss of ATP and build up of toxins in the highly metabolically active regions will result in loss of contraction w/in 60 seconds of ischemia (affected portion of cardiac wall will stop contracting completely)
After 30 minutes of ischemia there will be irreversible injury to the myocardium (before this time point there is enough adenosine present to keep it going upon reperfusion)
What is the MoA of etanercept?
Causes TNF-alpha inhibition by linking soluble TNF-a receptor to the Fc component of IgG -> hence it is a soluble receptor decoy protein
How can you distinguish the activity of pharmaceutical biological agents by the suffixes used? What about the substems
- mab = monoclonal antibody
- cept = receptor molecule
- nib = kinase inhibitor
Substems are also used to identify drug targets (e.g. c = CV, f = fungal, tu = tumor) and origin of the antibody (e.g. o = mouse, u = human, xi = chimeric, zu = humanized)
How likely is chronic infection of HBV in adults vs. peds?
Adults = 10% become chronic Peds = 90% become chronic
What is the most specific marker for diagnosis of acute HBV infection?
IgM anti-HBc - because it is present in the window period when HBsAg has been cleared and anti-HBs not yet detectable
What is the MoA of Fenoldopam?
Selective Dopamine-1 receptor agonist (no effect on alpha/beta-Rs) -> activates adenlyl cyclase -> increased cAMP -> vasodilation of most arterial beds w/ emphasis on renal, coronary and mesentary -> significant reduction in systemic vascular resistance
This will drop BP and also lead to improved RBF and increased Na+ and H2O excretion -> good for managing short term severe HTN and all HTN emergencies