UWorld_3.21

Question 1

Mutations associated with Alzheimer disease

Answer 1

• Early onset (<60 yo)
  
  • Amyloid precursor protein (APP) @ chromosome 21
  • Presenilin 1 @ chromo 14
  • Presenilin 2 @ chromosome 1
• Late-onset
  
  • Apolipoprotein E`4

Question 2

Contraindications for use of OCPs

Answer 2

1. Prior thromboembolic event/stroke
2. hx of estrogen-dependent tumro
3. women > 35 who smoke heavily ==> higher risk of CV events
4. hypertriglyceridemia
5. decompensated or active liver disease
6. pregnancy

Question 3

Gross painless hematuria @ older adult ==> dx?

Answer 3

• urothelial cancer until proven otherwise
• most common = clear cell carcinoma <== renal tubular cells
  
  • high glycogen or lipid content on histologic prep

Question 4

RCA occlusion ==> dx + EKG findings?

LAD occlusion ==> dx + EKG findings?

LCX occlusion ==> dx + EKG findings?

Answer 4

• RCA ==> transmural ischemia @ inferior wall of L ventricle ==> ST elevations @ II, III, aVF
• LAD ==> anteroseptal transmural ischemia ==> ST elevation @ V1-V4
• LCX ==> lateral wall transmural ischemia ==> ST elevation @ V5, V6 & possibly I and aVL

Question 5

Locations of ovarian artery

Location of uterine artery

Answer 5

• ovarian a. w/in suspensory ligament
• uterine artery w/in transverse cervical ligament

Question 6

Calculating A-a gradient @ sea levle

Answer 6

• A = P_AO₂ = 150 - (PaCO₂/0.8)
• a = P_aO₂
• Normal A-a < 10-15

Question 7

Risk factors for gallstone formation

Answer 7

• “fat, fertile, female, forty”
• OCPs/Pregnancy ==> increased estrogen and progesterone
• estrogen ==> upregulated HMG-CoA reductase activity ==> supersaturation of bile with cholesterol
• progesterone ==> gallbladder hypomotility

Question 8

Pulsus Paradoxus ==> Ddx?

Answer 8

• = decrease in systolic BP > 10 mmHg w/inspiration
• acute cardiac tamponade
• constrictive pericarditis
• severe obstructive lung disease
• restrictive cardiomyopathy

Question 9

Microbio characteristics of Corynebacterium

Answer 9

• gram (+) rods
• non-motile, unencapsulated
• clumps ~ chines letters or V- or Y-shaped chains
• cytoplasm has metachromatic granules that stain w/aniline dyes

Question 10

RBF calculation

Answer 10

= PAH clearance / (1-Hct)

Question 11

S. pyogenes microbio characteristics

Answer 11

• gram + cocci in chains
• b-hemolytic
• susc. to bacitracin
• pyrrolidonyl arylamidase (PYR) positive

Question 12

Post-influenza bacterial pneumonia causes

Answer 12

• s. pneumo
• s. aureus
• h. influenzae

Question 13

Role of “P bodies” in cell

Answer 13

• cytoplasmic proteins that play a role in mRNA translation regulation and mRNA degradation

Question 14

Causes of exacerbation of mysathenia gravis

Answer 14

• myasthenic crisis = undertx <==ephodrium will improve sx
• cholinergic crisis = overtx <==ephodrium will not improve sx

Question 15

Consequences of HCV infection

Answer 15

1. acute hepatitis (+/-)
2. chronic hepatitis
3. slowly progressive to cirrhosis

Question 16

Serotonin precursor amino acid

Answer 16

tryptophan

Question 17

Glutamic acid ==> molecular product?

Histidine ==> molecular product?

Methionine ==> molecular product?

Tyrosine ==> molecular product?

Answer 17

• glutamic = GABA
• histidine = histamine
• methionine= cysteine, carnitine, taurine, lethicin
• tyrosine = thyroxine, dopamine, epinephrine, norepi, melanin

Question 18

Antidote for serotonin syndrome

Answer 18

• cyproheptadine = antihistamine + anti-serotonergic properties

Question 19

Verapamil: MOA, use, SE

Answer 19

• MOA = non-dihydropyriddine ca-channel blocker
  
  • slows conduction through AV nodes
• use = rate control in afib w/rapid ventricular response
• SE
  
  • constipation
  • gingival hyperplasia
  • bradycardia
  • first, second, or third degree AV node block

Question 20

Leoprolide impact @ male

Answer 20

• GnRH
• transient increase, then decrease in both T and DHT

Question 21

Vancomycin: MOA vs. Ceftriaxone: MOA

Answer 21

• Vanc binds D-ala (glycoproteins @ cell wall of bacteria)
• Ceftriaxone binds PBPs
  
  • PBPs = transpeptidases that cross-link peptidoglycan @ cell wall

Question 22

Most common cause of nephrotic syndrome in children

Answer 22

• MCD = fusion of foot processes on EM

Question 23

Watershed areas of the colon

Answer 23

• splenic flexure and distal sigmoid colon
• lie between major arteries ==> susc. to damage during hypotension/low perfusion states

Question 24

Lead placement in biventricular pacemaker

Answer 24

• 2-3 leads used
• first two = @ RA and RV via subclavian/SVC
• left ventricle pacer lies @ atrioventricular groove

Question 25

Characteristics of lac operon

Answer 25

• genetic sequence in E. Coli that codes for proteins requried for metabolism of lactose
• regulatory gene (i), promotor region (p), operator region (o) + three structural genes (z, y, a)
  
  • z = beta-galactosidase ==> lactose ==> glucose + galactose
  • y = transmembrane enzyme allows cell perm. to lactose
  • i = repressor protein ==> w/out lactose binds operator and prevents RNA pol binding to promotor
• lactose assoc. w/repressor ==> release of repressor ==> trxn of lac operon
• glucose ==> decreased aden cyclase ==> decreased cAMP ==> decreased expression of lac operon genes