UWorld_3.28

Question 1

DiGeorge due to…?

Answer 1

malformation of third and fourth pharyngeal pouch

Question 2

Prevention measures for acute organ rejection

Answer 2

-calcineurin inhibitors -corticosteroids

Question 3

Bio active form of pantothenic acid = ?

Answer 3

coenzyme A

Question 4

Rxn that requires coA

Answer 4

OAA ==> citrate (first step of Krebs cycle)

Question 5

Steps in active vit D synthesis

Answer 5

1. sunlight catalyzes first rxn: 7-dehydrocholesterol ==> cholecalciferol 2. @ liver: cholecalciferol ==> 25-hydrocholecalciferol 3. @ kidney: 25-hydrocholecalciferol ==> 1,25-dihydrocholecalciferol [1-alpha hydroxylase] 4. @ vit D excess ==> @ kidney: 25-hydrocholecalciferol ==> 24,25-dihydrocholecalciferol = inactive form [24-alpha hydroxylase]

Question 6

How does EBV enter B cells?

Answer 6

attaches to CD21 = cellular receptor for C3d complement component via gp350

Question 7

Process of PAH secretion @ proximal tubule

Answer 7

-taken up by endothelial cells and secreted into filtrate -accomplished via carrier-mediated transport

Question 8

Mechanism + testing for mushroom poisoning

Answer 8

-amatoxin (e.g. death cap toxin) ==> inhibition of DNA-dependent RNA pol II ==> inhibited mRNA production ==> apoptosis -test = alpha-amantin levels @ serum

Question 9

Cystinuria presentation/mechanism

Answer 9

-defect in transporter of ornithine, lysine, arginine, cystine - ==> nephrolithiasis/renal colic in teens-20s -hexagonal cystine crystals

Question 10

Histo appearance of carcinoid tumors

Answer 10

nests or sheets of cells w/eosinophillic cytoplasm + round/oval stippled nuclei

Question 11

Trazadone: use, SE

Answer 11

use: sedation for insomnia w/depression in conj. w/SSRIs SE: priapism (extended erection)

Question 12

Venlafaxine: drug category

Answer 12

SNRI

Question 13

Active vs. Inactive RB

Answer 13

-active = hypophosphorylate ==I G1/S transition -inactive = hyperphosphorylated

Question 14

Histoplasma endemic locations

Answer 14

Ohio & MS river basins; found in bird and bat droppinga

Question 15

Most important risk factor for development of intimal tears ==> aortic dissection

Answer 15

HTN

Question 16

Anaplastic definition/characteristics

Answer 16

Anaplastic = cells w/complete lack of differentiation 1. loss of polarity/complete disorganization; e.g. sheets 2. variation in cell/nuclear shape and size (pleomorphism) 3. high N-C ratio w/hyperchromic nuclei & clumped chormatin 4. numerous, abnormal mitotic figures 5. giant cell formation

Question 17

First vs. Second Generation Anti-Histamines + examples

Answer 17

-first gen= hydroxyzine, promethazine, chlorpheniramine, diphenhydramine ==> antiH1 + SE: antimusc + anti-serotonergic (increased appetite) + alpha-adren (postural hypotension) -second gen = fexofenadine, cetirazine ==> much less SE/sedation

Question 18

Kussmual sign

Answer 18

-paradoxically elevated JVP during inspiration (normally decreases) <== due to restriction in RV filling capacity -sign of constrictive pericarditis

Question 19

Characteristics of drugs w/primarily hepatic clearance

Answer 19

high lipophillicity & Vd

Question 20

Homeobox ==>

Answer 20

transcription factors

Question 21

Causes of upper quad/low quad hemianopsia

Answer 21

upper quad = contralateral temporal lesion ==> disruption meyers loop = fibers carrying contralateral visual field upper quadrant vision (#4) lower quad = contralateral parietal lesion ==> disruption of fibers carrying contralateral visual field lower quad vision (#5)

Question 22

Hypo- or hyper-pigmented patches that are more visible after tanning ==> dx?

Answer 22

• Pityriasis versicolor <== Malassezia furfur
• ==> Spagghetti and meatballs appearance on KOH prep

Question 23

Important allosteric activator of gluconeogenesis

Answer 23

• [@mito] Acetyl-CoA stimulates pyruvate carboxylase: Pyruvate ==> OAA
• [@mito] OAA ==> malate ==> cytosol
• [@cytosol] malate ==> OAA ==> PEP [via PEPCK]

Question 24

Molecular stimulators of PMN chemotaxis

Answer 24

• IL-8 <== produces by macrophages
• C5a = complement = also chemotaxis for eosinophils, monocytes, and basophils
• LTB4

Question 25

Histone characteristics

Answer 25

• H1 = non-core ==> increased packaging w/linkage of nucleosome
  
  • H2A, H2B, H3, H4 = nucleosome core proteins

Question 26

Sudden, severe headache w/out focal neurologic deficits ==> sx?

Answer 26

• subarachnoid hemmorhage <== commonly due to rupture of berry aneurysm @ COW
• assoc. w/ED, ADPCKD

Question 27

Hepcidin role/source

Answer 27

• Hepcidin = APR produced by liver parenchyma = major control of iron homeostasis
• Hepcidin ==> internalization of ferroportin on cells ==> decreased intestinal iron absorption + inhibition of iron release by macs

Question 28

Most common cause of fatigue + new-onset murmur in young adult

Answer 28

bacterial endocarditis

Question 29

Commonly used drugs in MRSA infections + MOA

Answer 29

• Vancomycin: binds D-ala-D-ala subunits ==> prevents membrane formation
• Daptomycin: disrupts cell membrane through formation of transmembrane channels
• Linezolid: inhibits protein synthesis by binding 50S subunit

Question 30

SE:

Vancomycin

Daptomycin

Linezolid

Answer 30

• Vanc = Red man; nephrotoxicity
• Daptomycin = myopathy & CPK elevation
• Linezolid = thrombocytopenia, serotonin syndrome, optic neuritis

Question 31

Formulas for calculating CO

Answer 31

• CO = SV x HR
• CO = O2 consumption/arteriovenous O2 difference

Question 32

Cardiac tissue conduction velocity

Answer 32

• Fastest to slowest:
• Purkinje
• Atrial m.
• Ventricular m
• AV node
• “Park At Ventura Ave”