Misc. UWorld Stuff

Question 1

Tx of drug-induced Parkinsonism?

Drug class + 2 examples

Answer 1

Anticholinergics

benztropine and trihexyphenidyl

Question 2

How can left atrial pressure be measured?

Answer 2

Pulmonary artery occlusion pressure (PAOP)

AKA pulmonary capillary wedge pressure

• PA catheter (Swan-Ganz) used to dx pulm htn + in critical care
• Catheter placed in pulmonary artery, inflated, and P backs up to catheter tip from LA + is measured

Question 3

What may be cause of disseminated mycobacterial infection in childhood?

Why?

How can these kids be tx?

Answer 3

Interferon Signaling Deficiency

• i.e. AR deficiency of IFN-y receptor
• infected macrophages produce IL-12 > stimulate T/NK production of IFN-y > stimulates macrophage IC killing of mycobacteria (via JAK1/2 > STAT1)
• tx with life-long anti-mycobacterials

Question 4

Generally, what are serum Ca and PTH levels like in primary osteoporosis patients?

Answer 4

Normal

(wrongly answered low Ca and high PTH)

Question 5

What is the mnemonic for structures arising from neural crest cells?

Answer 5

MOTEL PASS:

• Melanocytes
• Odontoblasts
• Tracheal cartilage
• Enterochromaffin cells
• Laryngeal cartilage
• Parafollicular cells (thyroid)
• Adrenal medulla + all ganglia
• Schwann cells
• Spiral membrane

Question 6

Mutation in primary myelofibrosis

Answer 6

JAK2

same as in PV, and ET

(treatable with ruxolitinib, a JAK2 inhibitor)

Question 7

Mutations in…

acute promyelocytic leukemia?

CLL?

Burkitt?

Mantle cell lymphoma?

Answer 7

• APL - t(15;17) PML/RARalpha
• CLL - increased BCL2 expression
• Burkitt - t(8;14) involving c-myc via EBV
• Mantle cell - t(11;14) cyclin D1 overexpression

Question 8

what is cumulative incidence?

Answer 8

total number of new cases of a disease during a given period divided by number of people at risk during that period

Question 9

Antidote for cyanide poisoning and its mechanism

Answer 9

Amyl Nitrate

• cyanide binds Fe3+, inhibiting mitochondrial cytochrome c oxidase > red skin, tachypnea/-cardia, headache, lactic acidosis + decr. veno-arterial O2 gradient
• amyl nitrate oxidizes Fe2+ in hemoglobin to form Fe3+ (methemoglobin) which binds + sequesters cyanide
• hydroxycobalamin and Na Thiosulfate can also be used (make nontoxic metabolites w/ Cn- > urinary excretion)

Question 10

What structure prevents normal ascent of a horseshoe kidney?

What are horseshoe kidney pts at increased risk of (5)?

Answer 10

inferior mesenteric artery

1. uteropelvic junction obstruction
2. recurrent infection
3. urolithiasis
4. Wilms tumor (kids)
5. Renal cell cancer (adults)

Question 11

Process of granuloma formation in TB (cell types etc.)

Answer 11

1. Macrophages phagocytose bacilli
2. Ms present Ags to T cells
3. CD4+ cells further stim macrophages
4. Macros may for Langhans giant cells (mult. nuclei in horseshoe formation)
5. (Macros also stim fibroblasts which help produce granulomas)

Question 12

Cryptococcus neoformans

morpho, epidem, infection, dx, tx

Answer 12

• yeast w/ polysacch capsule; round/oval with narrow-based bud
• bird poop; inhaled; AIDS pt CD4 < 100
• meningoencephalitis (fever, HA, confusion)
• India ink > bubbly budding yeast; latex agg of CSF for polysacch Ag; Sabouraud culture
• ampho B / flucytosine induction; fluconazole maintenance

Question 13

How much of filtered water is absorbed in the different parts of the nephron?

Answer 13

• PCT - ~60% regardless of hydration status
• DL henle - ~20% due to corticopapillary gradient
• AL henle + early DCT - impermeable
• cortical + medullary CD - up to ~20% based on ADH > aquaporin translocation

Question 14

Changes in levels of what molecule are seen in narcolepsy?

where?

Answer 14

decreased hypocretin-1

• neuropeptides hypocretin-1 and 2 (orexin 1/2) made in lateral hypothalamus; promote wakefulness and inhibit REM sleep
• normally detectable in CSF, but not elsewhere

Question 15

Condition in which tyrosine becomes an essential AA

biochemical consequences + symptoms of the condition?

Answer 15

Phenylketonuria

• AR deficiency of Phe hydroxylase inhibits Phe > Tyr conversion
• excess Phe inhibits Tyr hydroxylase > decr. melanin (fair skin)/ catecholamine production
• intellectual disability by 6 mos; seizures, eczema, low pigmentation, “musty” odor

Question 16

Perinatal Hep B infection

• risk factors
• clinical findings
• prevention

Answer 16

• maternal viral load + HBeAg level
• immune tolerance (no sx / low-normal LFTs); high chronic risk; high viral load + HBeAg in baby
• HBsAg vacc + Ig within 12 hrs birth; maternal anti-viral tx; other routine vacc; serology 3 months after 3rd HB vacc dose

Question 17

a holosystolic murmur heard at the apex subsides after diuretic + vasodilator treatment

what was the cause of the murmur + why did the tx help?

Answer 17

• functional mitral regurgitation due to transient hemodynamic changes (NOT anatomical issues such as deformed cusps, calcified annulus, ruptured papillary muscles, etc.)
• diuretics > decreased preload and end-diastolic LV volume > less LV dilation > less mitral dysfunction
• vasodilator > decreased afterload > decreased intraventricular systolic pressure > less mitral dysfunction

Question 18

How is urinary pH buffered when large amounts of H+ ions must be excreted (as in DKA)?

Answer 18

Buffers such as NH3 and HPO4^2- in the tubules bind H+ ions to form NH4⁺ and H2PO4^-

• NH3 (ammonia) is most important as it can be greatly increased via Gln metabolism in acidosis

Question 19

Sx of Lithium toxicity (acute vs. chronic)

Conditions / factors which increase Li toxicity

Answer 19

• acute = GI > N/V/D
• chronic = neuro > confusion, agitation, ataxia, tremor, fasciculations (twitch)
• volume depletion (decr. GFR) and drugs (thiazides, NSAIDs, ACE-I, tetracyclines + metronidazole)
• (thiazides via decr. DCT Na reabs > stim PCT Na/Li reabs.)

Question 20

what are the 2 main components of “advance directives”?

Answer 20

1. living will - specifies end-of-life wishes re intubation, CP resuscitation, enteral feeding, etc.
2. healthcare proxy - specifies individual who will make HC decisions for pt if they are unable to

Question 21

What are type I and type II error?

And the “power” of a study?

Answer 21

• Type I error (alpha) - probability of seeing a difference when there is no real difference
• Type II error (beta) - probability of not seeing a difference when in reality there is one
• Power is the probability of a study seeing a difference when there is one, so P = 1 - beta

Question 22

What are the 2 clinical tests for hypocalcemia with fancy guys’ names?

Answer 22

• Chvostek sign - tapping facial nerve (CN VII) elicits nose/lip twitching
• Trousseau sign - bp cuff inflation > carpal spasm (flexion of wrist/thumb, extension of fingers)

Question 23

sensory innervation of tongue

Answer 23

• Anterior 2/3:
  
  • sensory: lingual nerve (CN V/3)
  • gustatory: chorda tympani (CN VII)
• Posterior 1/3:
  
  • sensory + gustatory: glossophar. n. (CN IX)

Question 24

What are the 3 sets of nephric systems that arise from the nephrogenic cord?

What do they become?

Answer 24

1. Pronephros - completely regresses
2. Mesonephros - Wolffian duct (vas def, epidid); regress > Gartner’s duct in females
3. Metanephros - induced by ureteric bud (>collecting system); becomes all of nephron from glom to DCT

Question 25

What are the **two** functions of type II pneumocytes?

Answer 25

* surfactant production * proliferation in response to injury (progenitors for type I pneumocytes)

Question 26

what is **number-needed-to-harm**?

Answer 26

* # ppl who must be treated before 1 additional adverse event occurs * calculated using the _absolute risk increase_: * **NNH = 1 / ARI**

Question 27

What is **absolute risk increase**?

Answer 27

the difference in adverse event rate between two study groups * 60/100 people die in a tx grp (60%) and 69/120 in a ctrl grp (57.5%) so ARI is 2.5%