3/16 UWORLD test # 45

Question 1

Q 1. What is selection bias. Example?

Answer 1

• selection of experimental group that does not represent GENERAL POPULATION
• ex: selection of samples from hospitalized patients- Berkson bias

Question 2

Q 2. kid, non-billous vomiting, prominent peristalsis on epigastric area, oval mass on epigastric area. what is going on? derived from what cell type?

Answer 2

pyloric stenosis

smooth muscle cell hypertrophy

Question 3

Q 6. Failure to ceftriaxon therapy for Nisseria/Chlamydia co-infection. What treatment next?

Answer 3

Different type of macrolide (azithromycin, erythromycin) and doxycycline

Question 4

Q 7. Of all hallucinogens, which one only presents nystagmus & psychomotor agitation (loss of coordnation, jerky movements..)

Answer 4

phencyclidine

Question 5

Q 7. MOA of phencyclidine?

Answer 5

NMDA (N-Methyl-D-Asparate) receptor antagonist

Question 6

Q 8. Phenelzine

• MOA
• side effect (2)

Answer 6

• MOA-A &B inhibitor
  1. hypertensitve crisis (especially with ingestion of tyramine, catchecolamine releasing factor)
  2. mood reactivity: feeling much better (than usual) in response to positive events

Question 7

Q 9. most commonly fractured carpal bone? physical examp finding? what is complication for this bone fracture? why?

Answer 7

• scaphoid
• tenderness with palpation on snuff box
• avascular necrosis: dosral scaphoid branch of radial artery enter near scaphoid pole and supply blood in retrograde fashion. With scaphoid fracture, this artery supply will not be impaired

Question 8

Q 10. Apart from influenza B virus, what another virus can cause genetic variation by reassortment? why?

Answer 8

rotavirus

10-12 gemoe segments

Question 9

Q 12. what is unique about smooth ER in terms of biosynthesis? what 2 cells are smooth ER rich?

Answer 9

Smooth ER contains enzymes for steroid and phospholipid biosynthesis

• hepatocytes & adrenal cortex (corticosteroid)

Question 10

Q 13. patient serum mixed with mixture of cardiolipin shows flocculation. what test is this? what does this suggest? two possible scenario?

Answer 10

presence of cardiolipin antibody
(flocculation means aggultination)

=> VDRL/RPR test

• syphilus infection
• anti-phoshpolipid syndrome

Question 11

Q 13. Is VDRL/RPR test specific for syphilis infection? why or why not?

Answer 11

no.

It just measures existence of human antibody that acts against cytoplasmic contents (cardiolipin) released by lysis of syphilis. Doesn’t tell whether syphilis is alive or infectious

Question 12

Q 13. Another test for syphilis infection that is more specific than VDRL/RPR test? what is this test looking for?

Answer 12

FAS-FTA

detects spirochetal antibodies that directly target syphillis

Question 13

Q 14. Neurokinin1 (NK1) receptor is involved in what physiological process? mechanism?

Answer 13

induce vomiting

• release of substance P

Question 14

Q 14. Targets for

• ondansetron
• metoclopramide

Answer 14

ondansetron: 5HT3 receptor antagonist
metoclopramide: dopamin receptor antagonist

Question 15

Q 15. What is stillbirth?

Answer 15

the birth of infant that has died before delivery

Question 16

Q 15. stillbirth, pleural effusion, pulmonary hypoplasia, ascites: description of what?

Answer 16

fetal hydrops

profound anemia -> congestive HF
-> pleural effusion/ ascities/ pulmonary hypoplasia

Question 17

Q 15. What infection is associated with fetal hydrops?

bacteria? virus? enveloped? DNA? RNA?

Answer 17

Parvovirus

ssDNA (smallest DNA), not enveloped

*sketchy: one single lane on floor, small town (small DNA). kid playing with david statue (not enveloped)

Question 18

Q 17. Is femoral vein medial or lateral to femoral artery?

Answer 18

medial

• in terms of femoral stuff (catheter insertion to femoral vein, femoral hernia) everything is MEDIAL
• femoral vein MEDIAL to femoral artery
• femroal hernia MEDIAL to femoral a/v

Question 19

Q 18. wheezing, prolonged expiration, eosinophilia: what is going on?

Answer 19

allergic asthma

Question 20

Q 19. Grave’s disease patient receiving anti-thyroid medications come clinic with fever and sore throat. What is going on? next step?

Answer 20

• thionamide (PTU, methimazole) induced agranulocytosis -> infection
• CBC for WBC count

Question 21

Q 20. Associated gene?

• development of late colon adenoma from early colon adenoma
• development of colon carcinoma from late early colon adenoma

Answer 21

• KRAS: still adenoma, but LATE ADENOMA
  (cox-2 overexpression is also involved here)
• P53 : CARCINOMA

Question 22

Q 21. Wheezing and poor air movement in lung. Liver biopsy with periodic Acid Schiff stain shows pink granules. Diagnosis?

Answer 22

alpha1 antitrypsin deficiency

pathoma p.90

• remember alpha 1 antitrypsin deficiency affects BOTH liver and lung

Question 23

what does codominant trait mean? example of disease that shows codominant trait?

Answer 23

either single or two alleles can cause defect

alpha1- antitrypsin deficiency
Z- increased susceptibility to develop emphysema after smoking
ZZ- panlobular emphysema

Question 24

Q 22. thiazide vs. loop diuretics: which one shows stronger symptom relief affect in acute HF? why?

Answer 24

loop diuretics shows better symptomatic relief

thiazide absorbs only small amount of sodium (DCT is more distal than loop). Thiazide is not as effective as loop diuretics

Question 25

Q 24. Unilateral shrunken kidney & hypertension: what is the most likely etiology?

Answer 25

ischemic injury due to unilateral renal artery stenosis

Question 26

Q 25. Apart from atropine, what can be used to treat B-blocker overdose? explain mechanism of action

Answer 26

Glucagon

glucagon -> increased cAMP -> increased PKA

• > increased intracellular Ca2+ in heart
• > increased contractility/HR

Question 27

Q 26. Glycogenolysis acts as primary energy source upon starving for how long?

Answer 27

first 12-18 hours of starving

Question 28

Q 26. What two enzymes in gluconeogenesis are required to bypass pyruvate kinase? Reactions of each enzyme? required cofactor?

Answer 28

pyruvtae kinase (PEP-> pyruvate) is unidirectional. So gluconeogensis can not use it.

• pyruvate carboxylase (needs biotin)
  : pyruvate -> oxaloacetate
• PEP carboxykinase (biotin not needed)
  : oxaloacetate -> PEP

Question 29

Q 29. Glomangioma

• what is this?
• location?
• role of the original cell of this tumor?

Answer 29

• tumor of glomus body
• underneath nail bed
• thermoregulation: glomus body shunts blood away from the cold spot to prevent loss of heat

Question 30

Q 30. CTFR chloride channel that is mutated in cystic fibrosis: is this channel ATP dependent? voltage dependent? or depends on other molcules?

Answer 30

CTFR is ATP dependent chloride channel

Question 31

Q 33. location of VSD heart murmur?

Answer 31

tricuspid area

: left 5th sternal border

Question 32

Q 35. ADPKD patient come in clinic with headache. what is going on?

Answer 32

berry aneurysm -> subarachnoid hemorrhage

Question 33

Q 36. adnexal mass is buzz word for what?

Answer 33

ovarian cancer

not necessarily need to be cancer, but adnexal area refers to area around ovary and fellopian tube

Question 34

Q 37. Pregnant, bleeding everywhere (gums, vaginal, IV line sites..) with low platelet count.

• diagnosis?
• etiology?

Answer 34

• DIC in obsterics

tissue factor is enriched in placental trophoblast
-> tissue factor moving back into maternal circulation
-> initiation of coagulation/ formation of microthrombi
-> used up platelet -> bleeding
anemia due to microthrombi and bleeding

Question 35

Q 40. Explain the mechanism that how heart gets bigger during transient ishemia

Answer 35

transient ischemia

• > lack of ATP synthesis
• > ATP dependent transporters (Na/K+ APTase, SERCA- Sarcoplasmic Reticulum Ca2+-ATPase) not working
• > accumulation of intracellular Na+ and Ca2+
• > water dragged intracellularly