UWorld_3.23

Question 1

Characteristics of mytonic dystrophy

Answer 1

• 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

Question 2

Beta blocker effects in thyrotoxicosis

Answer 2

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

Question 3

Neurophysin characteristics

Answer 3

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

Question 4

Enzymes that incorporate iron into heme molecule

Answer 4

• ferrochelatase
• delta-aminolevulinic acid

Question 5

Formation of delta-aminolevulinic acid

Answer 5

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

Question 6

N5-formyl-tetrahydroflorate impact on antimetabolite neoplastic drugs

Answer 6

• 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

Question 7

Blood gas/pulmonary consequences of PE

Answer 7

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

Question 8

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

Answer 8

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

Question 9

Anti-pseudomonals

Answer 9

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

Question 10

Heparain: MOA

Answer 10

• binds antithrombin III and increases action

Question 11

Drug-induced lupus: association

Answer 11

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

Question 12

Mast stablizing agents

Answer 12

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

Question 13

Niacin SE

Answer 13

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

Question 14

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

Answer 14

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

Question 15

HBV vs. HCV histologic appearance

Answer 15

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