UWorld_3.23 Flashcards Preview

USMLE Step 1 > UWorld_3.23 > Flashcards

Flashcards in UWorld_3.23 Deck (15)
1

Characteristics of mytonic dystrophy

  • AD, trinucleotide CTG repeat myotonia-protein kinase gene
  • ==> atrophy of type 1 m. fibers
  • ==> difficulty releasing doorknob/handshake
  • other features:
    • **cataracts
    • frontal balding
    • gonadal atrophy

2

Beta blocker effects in thyrotoxicosis

  • decrease noradgrenergic responses
  • decreased T4 ==> T3 conversion @ periphery

3

Neurophysin characteristics 

  • carriers of oxytocin and ADH from paraventricular and supraoptic (ADH) nuclei ==> hypothalamus
  • mutation @ neurophysin II = most common cause of central DI

4

Enzymes that incorporate iron into heme molecule 

  • ferrochelatase
  • delta-aminolevulinic acid

5

Formation of delta-aminolevulinic acid

  • succinyl-coA + glycine ==> delta-aminolevulinic acid
    • in presence of pyridoxal phosphate
  • delta-aminolevulinic acid elevated in lead poisining

6

N5-formyl-tetrahydroflorate impact on antimetabolite neoplastic drugs

  • reverses effects of methotrexate
    • bypasses reduction step of DHF (blocked by metho)
    • can act as a cofactor to thymidilate synthase
    • used to "rescue" healthy cells from metho tox
  • potentiates 5-FU effects
    • strengthens 5-FU assoc. w/thymidilate synthase

7

Blood gas/pulmonary consequences of PE

  • PE ==> V/Q mismatch ==> hypoxemia ==> increased respiratory drive/hyperventilation
  • hyperventilation ==> hypocapnea ==> respiratory alkalosis

8

Large, pedunculated mass in LA + mid-diastolic rumble murmor ==> dx?

  • atrial myxoma = scattered cells in mucopolysacc stroma
    • increased size ==> positional sx
  • angiogenesis ==> bleeding; friable mass
  • secretes IL-6 ==> constitutional sx; weight loss, fever

9

Anti-pseudomonals

  • Pip-Taz
  • [some] Cephs
    • Cefatadazine
    • Cefepime
  • Gentamicin
  • [some] fluoro
    • ciprofloxacin
    • levofloxacin
  • carbapenems

10

Heparain: MOA

  • binds antithrombin III and increases action

11

Drug-induced lupus: association

  • drugs metabolized by liver acteylation
  • hydralizine
  • procainamide
  • slow-acetylators are @ higher risk

12

Mast stablizing agents

  • cromolyn 
  • nedocromil
  • inhibit mast cell degranulation regardless of stimuli present
  • 2nd line for tx of allergic rhinitis and bronchial asthma

13

Niacin SE

  • vasodilation ==> flushing 
    • can potentiate anti-htn meds ==> dosage decrease
  • ==> increased insulin resistance
    • ==> dosage increase in DM meds

14

Cause of increased bleed in pt. w/severe kidney dysfxn

  • uremic bleeding issue
  • uremic toxins ==> interference w/platelet aggregation = qualitative platelet disorder
    • ==> increased bleeding time w/other coag labs normal

15

HBV vs. HCV histologic appearance

  • HBV = viral aggregrates in cytoplasm ==> "ground glass"
    • image on front
  • HCV = lymphoid aggregates @ portal tracts + focal areas of macrovesicular steathosis
    • image below

Decks in USMLE Step 1 Class (97):