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STEP1 Review > UWorld Test Review 4 > Flashcards

UWorld Test Review 4 Flashcards

1
Q

baseball pitcher with diminished strength on R elbow flexion and absent biceps reflex will also likely have sensory loss over:
a. lateral forearm
b. medial forearm
c. posterior arm
d. posterior forearm
e. thenar eminence

A

a. lateral forearm - due to injury of musculocutaneous nerve

musculocutaneous nerve (C5-C7): arises from lateral cord, innervates elbow flexors (biceps brachii, brachialis) + sensory to lateral forearm

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2
Q

malaria infections in sub-Saharan African are primarily due to ______, while those in South/Central America are primarily due to _______

A

sub-Saharan Africa = Plasmodium falciparum

South/Central America = Plasmodium vivax

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3
Q

which 2 malaria species need to be treated with medication that targets the dormant hepatic phase? name the drug used

A

Plasmodium vivax + Plasmodium ovale form hypnozoites in liver —> prevent reactivation with primaquine

[intraerythrocytic phase treated with chloroquine]

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4
Q

blue sclerae are characteristic of what genetic disorder?

A

osteogenesis imperfecta: defect in Type I collagen —> blue sclera + brittle teeth + bowing/fractures

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5
Q

Brushfield spots are seen in which genetic disorder?

A

Brushfield spots = hypopigmented spots in iris, seen in Down syndrome

Down’s due to endocardial cushion defects —> atrial septal defects, regurgitant AV valves

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6
Q

what are the cardiac findings of Turner syndrome?

A

aortic coarctation —> claudication (pain/cramping with exercise) + blood pressure discrepancy between upper/lower + diminished femoral pulses

often have bicuspid aortic valve

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7
Q

which of the following is the best alternative for a patient with stable angina (angina pectoris) who cannot tolerate aspirin?
a. apixaban
b. cilostazol
c. clopidogrel
d. enoxaparin
e. eptifibatide
f. naproxen

A

c. clopidogrel: irreversibly blocks P2Y12 (component of ADP receptors on platelets) —> prevents platelet aggregation

a. apixaban = factor X inhibitor
b. cilostazol = phosphodiesterase inhibitor
d. enoxaparin = LMWH
e. eptifibatide = glycoprotein IIb/IIIa inhibitor
f. naproxen = NSAID

^none of those are used for prevention in stable CHD

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8
Q

which of the following would cause a reduction in the plasma level of phenytoin?
a. amoxicillin
b. rifampin
c. fluconazole
d. cimetidine
e. omeprazole

A

b. rifampin - induces CYP450

… as does chronic alcohol use, barbiturates, carbamazepine, griseofulvin, modafinil, phenytoin, St. John’s wort

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9
Q

treatment of choice for extended-spectrum beta-lactamase (ESBL) organisms

A

carbapenems - ex, imipenem

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10
Q

which of the following drugs can promote venous thromboembolism?
a. alendronate
b. chlorthalidone
c. empagliflozin
d. liraglutide
e. raloxifene
f. sacubitril valsartan
g. spironolactone

A

e. raloxifene (and tamoxifen) - SERMs —> estrogen agonist activity causes prothrombotic state

a. alendronate = bisphosphonate
b. chlorthalidone = thiazide
c. empagliflozin = SGLT2 inhibitor
d. liraglutide = GLP-1 agonist
f. sacubitril valsartan = neprilysin (increases ANP/BNP) + valsartan
g. spironolactone = aldosterone antagonist

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11
Q

V1 vs V2 receptor for ADH

A

V1 —> vasoconstriction + prostaglandin release

V2 —> anti-diuretic response

[ADH acts on medullary collecting duct]

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12
Q

buildup of very long chain and branched-chain (phytanic) fatty acids due to impaired oxidation is hallmark of…

A

peroxisomal disorders, ex:

  1. Zellweger syndrome: presents in infancy with craniofacial abnormalities (large anterior fontanelle), hepatomegaly, neuro defects (hypotonia, seizures, delay)
  2. X-linked adrenoleukodystrophy: presents in child/adult with neuro deterioration + adrenal insufficiency
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13
Q

contrast 2 peroxisomal disorders

A
  1. Zellweger syndrome: presents in infancy with craniofacial abnormalities (large anterior fontanelle), hepatomegaly, neuro defects (hypotonia, seizures, delay)
  2. X-linked adrenoleukodystrophy: presents in child/adult with neuro deterioration + adrenal insufficiency
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14
Q

what is the effect of mushroom amatoxins on cellular function?

A

potent inhibitors of RNA polymerase II —> halted mRNA synthesis

[ex, from Amanita phalloides, aka death cap]

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15
Q

what causes the increase in maternal insulin resistance during pregnancy?

A

human placental lactogen (hPL): peptide hormone secreted by syncytiotrophoblast

—> increased maternal glucose allows glucose to cross the placenta for fetal consumption
—> also increase maternal proteolysis and lipolysis

so just think of hPL as the hormone making sure there are Plentiful Levels of nutrients !

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16
Q

25-hydroxyvitamin D vs 1,25-dihydroxy vitamin D

A

25-hydroxyvitamin D = storage form

1,25-dihydroxy vitamin D = active form (via 1-alpha-hydroxylase in kidneys), action mediated by binding vitamin D receptor

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17
Q

35yo w/ acute R knee pain and swelling. Pt treated for diarrheal illness -2 weeks. Joint aspiration reveals no bacteria. Which of the following is most likely associated with the joint symptoms?
a. C1 inhibitor deficiency
b. antistreptolysin O antibodies
c. HLA B27
d. positive serum antinuclear antibodies
e. positive serum rheumatoid factor

A

c. HLA B27

dx: reactive arthritis (follows GI infection/ enteritis): immune complexes involving bacterial antigens —> asymmetric oligoarthritis/ dactylitis + conjunctivitis and urethritis

reactive arthritis = spondyloarthropathy, preferentially affects HLA B27-positive people

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18
Q

what type of malignancy arises from each of the following? also provide a specific histology or gross pathology finding:
a. collecting duct cells
b. proximal renal tubules
c. renal pelvis lining

A

a. collecting duct cells —> oncocytomas: gross pathology shows homogeneous brown tumor with central stellate scar

b. proximal renal tubules —> renal cell carcinoma: most are clear cell carcinomas, gross pathology shows sphere-like mass of golden-yellow tissue with focal necrosis + hemorrhage

c. renal pelvis lining —> urothelial carcinoma: form papillary tumors supported by thin fibrovascular stalk

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19
Q

decreased metabolic degradation of a phospholipid substrate to ceramide would cause which findings? what is the dx?
a. abnormally shaped bones and corneal clouding
b. coarse facial features and cardiac dysfunction
c. neuropathic pain and angiokeratomas
d. retinal opacification and splenomegaly

A

d. retinal opacification and splenomegaly

dx = Niemann-Pick disease: AR deficiency of sphingomyelinase (converts sphingomyelin —> ceramide)

lipid-laden foam cells accumulate in liver, spleen, CNS, retinal ganglion cells (cherry-red macula)

[more common among Ashkenazi Jewish]

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20
Q

32yo M receives tick bite in the woods, a week later has fever/chills and myalgia. PE shows diffuse maculopapular rash. Labs show leukopenia, thrombocytopenia, elevated aminotransferase. Microscopic evaluation of blood shows mulberry-shaped intracytoplasmic inclusions in monocytes. Dx?

A

Ehrlichia chaffeensis: harbored by white-tailed deer in SW/SE/mid-Atlantic, transmitted via lone star tick, infects mononuclear cells —> mulberry shaped inclusions

tx = doxycycline

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21
Q

which of the following should be monitored in a patient taking amphotericin B?
a. Platelet count.
b. Serum calcium.
c. Serum creatinine phosphokinase.
d. Serum potassium and magnesium.
e. Thyroid stimulating hormone.

A

d. Serum potassium and magnesium

Amphotericin B = polyene antifungal, notorious for its renal toxicity

Severe hypokalemia and hypomagnesemia can occur due to increased distal tubular membrane permeability

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22
Q

What are the adverse effects of the four drugs used to treat tuberculosis?

A
  1. rifampin: GI effects, rash, red-orange body fluids, cytopenia
  2. isoniazid: neurotoxicity (give vitamin B 6/pyridoxine), hepatotoxicity
  3. pyrazinamide: hepatotoxicity, hyperuricemia
  4. ethambutol: otic neuropathy
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23
Q

hypogonadism + small, firm testes =

A

Klinefelter syndrome: hypogonadism due to hyalinization/fibrosis of testes

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24
Q

newborn with low-set ears, small mandible (micrognathia), prominent occiput, hypertonia (clenched hands with overlapping fingers), rocker bottom feet =

A

trisomy 18 (Edwards’ syndrome) - may also present with cardiac anomalies (ventricular septal defect, PDA), horseshoe kidney, Meckel’s diverticulum, etc

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25
Q

most common triggers for drug-induced hemolytic anemia? 3

A
  1. anti-inflammatory medications
  2. penicillins
  3. cephalosporins (ceftriaxone)
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26
Q

football player with shoulder injury - bruising on posterior aspect, normal abduction but pain with external rotation against resistance
a. infraspinatus
b. subscapularis
c. supraspinatus
d. teres minor

A

a. infraspinatus

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27
Q

in which patients should you expect purulent pericarditis vs fungal pericarditis? what is the most likely causative organism of each?

A

purulent pericarditis - most likely staph. aureus, seen in pts with vascular catheters or portals from skin to blood/pericardium

fungal pericarditis - most likely Candida albicans, seen in pts with parenteral feeding, prolonged corticosteroid use, immunosuppression due to malignancy

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28
Q

how does tuberculoid leprosy (TT) vs lepromatous leprosy (LL) present>

A

both caused by Mycobacterium leprae, response depends on strength of cell-mediated immunity:

tuberculoid leprosy (TT): less severe/self-limited due to intact Th1 response —> mild skin plaques, hypopigmentation, hair follicle loss, focally decreased sensation

lepromatous leprosy (LL): most severe, in patients with weak Th2 response —> diffuse plaque-like hypopigmentation w/ hair loss, paresis, regional anesthesia, testicular destruction, blindness

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29
Q

acute transplant rejection (weeks-6months out) is mediated by what immune response?

A

cell mediated - host T cell sensitization against graft MHC antigens

causes graft dysfunction with histology showing dense, mononuclear infiltrate

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30
Q

4yo w/ history of intellectual disability presents with prominent forehead and broad nose, and there is bilateral corneal hazing. Heart, liver, and spleen are enlarged. Sampling of coronary arteries would likely reveal intimal accumulation of…

A

heparan sulfate accumulation

dx = Hurler syndrome: type I mucopolysaccharidosis due to defect GAG metabolism (alpha-L-iduronidase deficiency)

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31
Q

which antibiotics are affected by the following mechanisms of resistance:
a. drug efflux
b. mutation in DNA gyrase
c. mutation in RNA polymerase

A

a. drug efflux - tetracyclines + sulfonamides
b. mutation in DNA gyrase - quinolones
c. mutation in RNA polymerase - rifampin

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32
Q

elevated 17-hydroxyprogesterone + increased testosterone = disruption of:
a. 11–deoxycorticosterone conversion to corticosterone
b. 11–deoxycortisol conversion to cortisol.
c. Pregnenolone conversion to 17-hydroxyprenenolone
d. Progesterone conversion to 11–deoxycorticosterone

A

d. Progesterone conversion to 11–deoxycorticosterone

dx: 21-hydroxylase deficiency —> buildup of 17-hydroxyprogesterone, which is shunted towards androgen production

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33
Q

21yo F presents w/ recurrent self-limited colicky abdominal pain. Has also had an episode of facial swelling that resolved spontaneously. Complement proteins C1 is excessively cleaving C2 and C4. Which of the following is most likely increased in this patient?
a. antinuclear antibody.
b. Bradykinin.
c. free hemoglobin
d. Renin

A

b. Bradykinin

dx: C1 inhibitor (C1INH) deficiency: prevents C1-mediated cleavage of C2 and C4, limiting activation of complement cascade

Also blocks conversion of kininogen to bradykinin —> bradykinin induced angioedema

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34
Q

name for infectious agents that can cause diarrhea with a very small inoculum

A
  1. Shigella flexneri
  2. Campylobacter jejuni
  3. Entamoeba histolytica.
  4. Giardia lamblia

primarily due to ability to survive in the low pH gastric environment

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35
Q

Pt w/ myasthenia gravis is treated with pyridostigmine but now experiences abdominal cramping, nausea, sweating, and diarrhea. Which of the following can be used to control these new symptoms?
a. Fluoxetine.
b. Glycopyrrolate.
c. Pilocarpine.
d. Prazosin.
e. Propranolol.

A

b. Glycopyrrolate = selective muscarinic antagonist

a. Fluoxetine = SSRI
c. Pilocarpine = nonselective muscarinic agonist.
d. Prazosin = alpha-1 adrenergic antagonist.
e. Propranolol = beta-blocker

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36
Q

during pregnancy, increased _____ levels promote sacroiliac joint laxity and widening of the pubic symphysis to help facilitate vagina delivery

A

during pregnancy, increased relaxin levels promote sacroiliac joint laxity and widening of the pubic symphysis to help facilitate vagina delivery

relaxin = hormone produced by corpus luteum (1st trimester) and placenta (2nd/3rd trimester)

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37
Q

Pt with total hip replacement following a femoral neck fracture now has lower extremity deficits including weakness in knee flexion, dorsiflexion, and plantar flexion and inversion. They also have numbness on dorsal foot and absent ankle reflex. Which nerve is injured?

A

sciatic nerve

sciatic nerve - knee flexion
common peroneal nerve - dorsiflexion, sensation to dorsal foot and posterolateral calf
tibial nerve - plantar flexion and inversion, ankle reflex

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38
Q

soft tissue infections with mouse-like odor following cat or dog bite =

A

Pasteurella multocida

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39
Q

which medication specifically should be avoided in a patient with hypertrophic cardiomyopathy? (4)

A

Those that decrease left ventricular blood volume —> worsen left ventricular outflow tract obstruction

  1. Nitrates – decrease preload
  2. Hydralazine – decrease afterload.
    3/4. dihydropyridine calcium channel blockers and ACEi - decrease both preload and afterload
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40
Q

which of the following should be periodically monitored during testosterone replacement therapy?
a. ECG
b. Hematocrit.
c. Serum cortisol
d. Serum creatinine.
e. serum TSH and thyroxine

A

b. Hematocrit

testosterone therapy can cause erythrocytosis —> increased blood viscosity —> venous thromboembolism

41
Q

what is the pathophysiology behind leukocyte adhesion deficiency?

A

defect in CD18 antigens necessary for the formation of integrins —> impaired leukocyte adhesion and endothelial transmigration

—> skin/mucosal infections without pus, impaired wound healing, delayed umbilical cord separation

labs show leukocytosis + neutrophilia (can’t migrate out of blood)

42
Q

What are the signs of mercury poisoning?

A

mercury inhibits catechol O-methyltransferase —> decreased catecholamine breakdown

neuropsych: tremor, insomnia, irritability

cardio: HTN, tachycardia

mucocutaneous: gingivitis, diaphoresis, desquamation of hands/feet

renal: tubular damage/ proteinuria

43
Q

How does selenium toxicity present?

A

G.I. disturbance (N/V) + hair/nail loss

44
Q

which of the following is a possible complication of hand foot and mouth disease?
a. Facial nerve palsy.
b. Keratitis.
c. Myocarditis.
d. Symmetric polyarthritis
e. Temporal lobe encephalitis

A

[caused by enterovirus]
c. Myocarditis

a. Facial nerve palsy = Lyme disease
b. Keratitis = HSV.
d. Symmetric polyarthritis = parvovirus B19.
e. Temporal lobe encephalitis = HSV

45
Q

which of the following is the best way to monitor the anticoagulation effect of warfarin?
a. activated partial thromboplastin time
b. Bleeding time.
c. Fibrinogen levels.
d. prothrombin time.

A

d. prothrombin time (PT) - because warfarin has a particularly strong effect on Factor VII

can also use international normalized ratio (INR): ratio of patient’s PT to a control

46
Q

which antifungal drugs inhibit cytochrome P450?

A

azoles

should avoid warfarin, cyclosporine, tacrolimus, oral hypoglycemics

47
Q

Pt w/ COPD presenting w/ SOB and cough productive of thick, green sputum for past 2 days. What are you thinking?

A

thick/green purulent sputum = release of myeloperoxidase from neutrophils = infectious acute exacerbation of COPD

most common viral: rhinovirus, influenza, RSV
most common bacterial: Haemophilus influenzae, Moraxella catarrhalis, Strep. pneumoniae

[noninfectious exacerbations include air pollution, pulmonary embolism, etc, but don’t present w/ green sputum]

48
Q

when do beta-hCG levels begin to rise during pregnancy, and what is its function?

A

blastocyst (day 3-4) forms inner embryoblast + outer trophoblast

trophoectoderm contains cytotrophoblasts (placental stem cells) + syncytiotrophoblasts

syncytiotrophoblasts invade endometrium and begin secreting beta-hCG + progesterone + human placental lactogen

beta-hCG prevents corpus luteum degradation —> sustained ovarian progesterone production to support pregnancy

49
Q

what is the role of each of the following in coagulation?
a. Hageman factor
b. kallikrein
c. prostacyclin
d. protein C
e. serotonin
f. thromboxane A2
g. ADP

A

a. Hageman factor (factor XII): activated by exposed collagen, activates intrinsic clotting pathway and also fibrinolysis

b. kallikrein: converts kininogen to bradykinin (vasodilation/permeability/pain)

c. prostacyclin: secreted by endothelium to inhibit platelet aggregation and cause vasodilation

d. protein C: inactivates factor Va and VIIIa

e. serotonin: released from delta granules of platelets and causes vasoconstriction

f. thromboxane A2: released from platelets and causes vasoconstriction and platelet aggregation

g. ADP: stimulates platelet aggregation

50
Q

which 2 of the following have directly opposing actions?
a. Hageman factor
b. kallikrein
c. prostacyclin
d. protein C
e. serotonin
f. ADP

A

c. prostacyclin: secreted by endothelium to inhibit platelet aggregation and cause vasodilation
f. ADP: released by platelets to stimulate platelet aggregation

a. Hageman factor = factor XII
b. kallikrein: converts kininogen to bradykinin
d. protein C: inactivates factor Va and VIIIa
e. serotonin: vasoconstriction

51
Q

which of the following is required to form aspartate from glutamate and oxaloacetate?
a. biotin
b. folic acid
c. niacin
d. pyridoxine
e. riboflavin

A

d. pyridoxine (B6): necessary for transamination and decarboxylation of amino acids

a. biotin (B7) - carboxylation
b. folic acid (B9) - nucleic acid synthesis
c. niacin (B3) - forms NAD+/NADP+
e. riboflavin (B2) - dehydrogenase rxns involving FMN and FAD

52
Q

which pulmonary pathology presents with finger clubbing?

A

interstitial lung disease - cause pulmonary fibrosis with thickening/stiffening of interstitium

—> increased lung elastic recoil, airway widening due to increased outward pulling (radial traction) by surrounding fibrotic tissue

53
Q

salivary secretion from the submandibular and sublingual is mediated by parasympathetic fibers originating in the _____ nucleus carried on the ______ nerve

A

salivary secretion from the submandibular and sublingual is mediated by parasympathetic fibers originating in the salivatory nucleus carried on the facial (CN VII) nerve via the chorda tympani and lingual nerves across the submandibular ganglion

54
Q

which bacterial toxins mediate the following effects?
a. disruption of cytoskeleton
b. inactivation of 60S ribosomal subunit
c. inactivation of elongation factor 2
d. inhibition of sodium reabsorption
e. stimulation of chloride secretion

A

a. disruption of cytoskeleton = C.diff cytotoxin B (depolymerizes actin)

b. inactivation of 60S ribosomal subunit = Shiga toxin (E. coli O157:H7 + Shigella)

c. inactivation of elongation factor 2 = C. diphtheriae toxin

d. inhibition of sodium reabsorption = enterotoxigenic E. coli heat-labile toxin (increases cAMP)
e. stimulation of chloride secretion = enterotoxigenic E. coli heat-labile toxin (increases cAMP)

55
Q

what is the effect of cystic fibrosis on the pancreas?

A

dehydrated/viscous secretions block lumen of pancreatic ducts —> exocrine and endocrine dysfunction

this leads to fibrosis/fat infiltration —> destruction of pancreatic islet cells —> CF-related diabetes

56
Q

what is the major virulence factor of the pathogen that most commonly causes epiglottitis?

A

Haemophilus influenzae type b (Hib): major virulence factor is polysaccharide capsule made of polymer polyribosylribitol phosphate (PRP)

PRP capsule prevents phagocytosis and complement-mediated lysis by binding Factor H (circulating regulator protein that prevents C3b deposition on host cells)

57
Q

how is filtration fraction (FF) determined?

A

FF = GFR / RPF

GFR calculated using inulin or creatinine clearance (freely filtered, insignificant reabsorption or secretion)

RPF (renal plasma flow) calculated using para-aminohippuric acid (PAH) clearance (mostly secreted)

58
Q

how does hyper-IgE syndrome present?

A

aka Job syndrome: AD defect in JAK-STAT signaling —> defective differentiation of Th17, therefore defective neutrophil migration

—> severe/chronic eczema, non inflammatory abscesses (Staph, Candida), sinopulmonary infections, retained primary teeth, dysmorphic facies

59
Q

increased levels of acetylcholinesterase in amniocentesis =

A

open neural tube defect (NTD) - because AChE is normally concentrated in CSF and should not be found in amniotic fluid

60
Q

what amniocentesis findings indicate Down Syndrome?

A

low AFP (alpha-fetoprotein)

61
Q

what does CXR show in a ruptured thoracic aortic aneurysm (TAA)? (3)

A
  1. tracheal deviation
  2. widened mediastinum
  3. enlarged aortic knob
62
Q

how does injury/compression to the ulnar nerve present at the elbow, wrist, and hand?

A

elbow - paresthesia in ulnar distribution

wrist - impaired flexion and adduction (flexor carpi ulnaris)

hand - clawing of 4th and 5th digits (medial portion of flexor digitorum profundus) + loss of sensation to 5th and mid-4th digits and hypothenar eminence

[ulnar nerve enters wrist through Guyon canal - between hook of hamate and pisiform]

63
Q

ulnar nerve compression can cause weakness of wrist [ab/adduction]

median nerve compression can cause weakness of wrist [ab/adduction]

A

ulnar nerve compression can cause weakness of wrist adduction

median nerve compression can cause weakness of wrist abduction

64
Q

why is serum T3 level often normal in patients with primary hypothyroidism?

A

patients will have elevated TSH, low T4, and normal T3

T3 is normal because it is produced mainly in peripheral tissue and has a short half-life (levels will fluctuate, correlates poorly with clinical status)

65
Q

phenotypic mixing

A

coinfection of a host cell by 2 viral strains, resulting in progeny virions that contain nucleocapsid proteins from one strain and unchanged parental genome of the other

no change in underlying viral genomes (no genetic exchange), so next gen. of virions revert to original, unmixed phenotypes

66
Q

which 2 enzymes of the heme synthesis pathway are inhibited by lead poisoning?

A
  1. ALAD (delta-aminolevulinate dehydrogenase) —> ALA buildup
  2. ferrochelatase —> protoporphyrin IX buildup
67
Q

what occurs during the early phase vs late phase of type I hypersensitivity?

A

early phase = superficial dermal edema and erythema (wheal and flare) via release of preformed histamine and leukotrienes from mast cells

late phase (2-10hr later) = tissue damage via stimulation of Th2 —> IL-5 —> activation of eosinophils —> release of major basic protein, peroxidase

68
Q

seborrheic keratosis vs actinic keratosis

A

seborrheic keratosis = tan/brown epidermal tumors appearing as either nearly flat macules or raised wart-like lesinons, velvety surface with “stuck on” appearance; rapid onset of numerous = Leser-Trelat sign, indicating gastric adenocarcinoma

actinic keratosis = unpigmented lesions of hyperkeratosis in sun-exposed areas

69
Q

what genital lesions occur during each stage of syphilis infection?

A

primary syphilis - chancre: painless ulcer, resolves spontaneously

secondary syphilis - condylomata lata: wart-like growths [pts also have diffuse maculopapular rash including palms/soles]

late/tertiary syphilis - gummas: painless indurated granulomatous lesions that progress to white-gray rubbery lesions that ulcerate, can also occur in organs [pts also have ascending aortic aneurysm + valve insufficiency]

70
Q

why would increasing the ventilator respiratory rate be helpful in a patient with cerebral edema?

A

CO2 is a potent vasodilator of cerebral vasculature - tachypnea causes hypocapnia and cerebral vasoconstriction, thereby decreased cerebral blood volume and intracranial pressure

71
Q

explain the process of ovulation induction therapy

A

for patients with anovulatory infertility

  1. exogenous gonadotropins (FSH) to stimulate ovarian follicular development
  2. once follicles appear mature on ultrasound, patient receives injection of hCG

because hCG/LH/FSH/TSH share common alpha subunit, hCG can bind/activate same receptors as LH —> mimics LH surge and acts as ovulation trigger

72
Q

gram-positive coccus that forms chains and exhibits a narrow zone complete hemolysis on blood agar

A

group B Streptococcus (GBS): colonizes ~50% of pregnant women, who are given intrapartum penicillin prophylaxis to prevent vertical transmission

major cause of neonatal sepsis, virulence factor = polysaccharide capsule which contains sialic acid residues that prevent phagocytosis via molecular mimicry

73
Q

Why do patients with Klinefelter syndrome develop gynecomastia?

A

atrophied, hyalinized seminiferous tubules —> low inhibin levels and damaged Leydig cells —> low testosterone —> lack of feedback, inhibition result in excess gonadotropin production (FSH, LH)

FSH upregulates aromatase, converting androgens into estrogens —> gynecomastia

74
Q

enthesitis (inflammation at bony insertions of tendons, ligaments, joint capsules) is suggestive of…

A

spondyloarthritis - often ankylosing spondyloarthritis, can also be psoriatic or reactive arthritis

75
Q

diaper rash that sparse skin folds and is effectively treated with petrolatum ointment is caused by:
a. abnormal keratin expression
b. altered local skin pH
c. increased hapten sensitization
d. local bacterial colonization

A

b. altered local skin pH

dx = irritant contact diaper dermatitis: most common form of diaper rash, caused by skin barrier breakdown due to exposure to urine and stool in diaper —> urease produced by fecal bacteria causes local increase in skin pH, which activates proteolytic enzymes

[hapten sensitization = allergic contact dermatitis, unlikely to resolve just with ointment]

76
Q

what is the cause of oculocutaneous albinism?
a. CD8+ mediated melanocyte apoptosis
b. decreased number of premelanosomes
c. disrupted keratinocyte melanin uptake
d. impaired melanin synthesis in melanosomes
e. reduced differentiation of neural crest cells into melanocytes

A

d. impaired melanin synthesis in melanosomes

a. CD8+ mediated melanocyte apoptosis = vitiligo
c. disrupted keratinocyte melanin uptake = Chediak-Higashi (OCA + pyogenic infections + coagulopathy)
e. reduced differentiation of neural crest cells into melanocytes = Waardenburg syndrome

77
Q

which of the following is the best initial treatment for a burn patient infected with Pseudomonas aeruginosa?
a. penicillin
b. Ceftriaxone.
c. Doxycycline
d. Cefepime.
e. Moxifloxacin.
f. Trimethoprim-sulfamethoxazole

A

d. Cefepime (4th gen), can also use ceftazidime (3rd gen)

78
Q

what are the symptoms of dermatomyositis? (2) with what underlying cause is this sometimes associated?

A
  1. Proximal muscle weakness
  2. inflammatory features of the skin – heliotrope rash (periorbital), Gottron papules (raised plaques on joints of hand)

can occur as a paraneoplastic syndrome associated with underlying adenocarcinoma (Overy, lung, pancreas)

79
Q

name 3 malignancies associated with an AD inactivating mutation in von Hippel Lindau (VHL) gene

A
  1. Hemangioblastomas
  2. Clear cell renal carcinoma.
  3. Pheochromocytoma.

caused by chromosome 3p deletion

VHL normally inhibits hypoxia-inducible factors (VEGF, PDGF)

80
Q

what is the major virulence factor of E. coli infection?

A

Lipid A - major virulence factor of lipopolysaccharide (LPS) that induces macrophages to release cytokines and cause septic shock

LPS = heat-stable component in outer membrane, released with destruction of bacterial wall or during cell division

81
Q

Why is therapeutic hypothermia helpful in improving neurological outcomes in hypoxia induced injury?

A

formation of reactive oxygen species after ischemic injury is temperature dependent

82
Q

Glucose transporters in which 2 tissues are insulin mediated?

A
  1. myocytes
  2. adipocytes

both use GLUT-4, which is responsive to insulin

83
Q

Which regions of the spinal cord are affected by subacute combined degeneration? (3)

A

low B12 (cobalamin) —> elevated methylmalonic acid (damaging to myelin)

  1. dorsal columns
  2. lateral corticospinal tracts
  3. spinocerebellar tracts
84
Q

What is the effect of altitude on pulmonary arterial resistance?

A

hypoxic pulmonary vasoconstriction occurs to minimize ventilation – perfusion mismatching and optimize pulmonary oxygen uptake —> increased pulmonary vascular resistance, which increases pulmonary arterial pressure

85
Q

impaired tetrahydrobiopterin synthesis would cause a deficiency of…
a. acetylcholine
b. GABA
c. phenylalanine
d. serotonin

A

d. serotonin

impaired BH4 synthesis —> elevated phenylalanine and decreased serotonin because BH4 is a cofactor for conversion of phenylalanine to tyrosine (tyrosine is precursor of serotonin)

would also see reduced catecholamines because tyrosine is a precursor of L-dopa, which is a precursor of catecholamines

86
Q

the following autoantibodies have high specificity for which diseases, respectively?
a. anti-centromere
b. anti-citrullinated peptides
c. anti-dsDNA

A

a. anti-centromere = CREST syndrome
b. anti-citrullinated peptides = rheumatoid arthritis
c. anti-dsDNA = systemic lupus erythematous

87
Q

pelvic surgeries, especially hysterectomies, carry a risk of damage to what nearby structure? where are 3 high risk locations?

A

risk of ureteral injury at either:
1. posterior to infundibulopelvic ligament (contains ovarian vessels)
2. lateral aspect of uterosacral ligament
3. beneath cardinal ligament (contains uterine vessels - “water under the bridge”)

88
Q

epiglottitis is caused by a:
a. Gram- cocci in pairs
b. Gram- coccobacilli
c. Gram- rods in chains
d. Gram+ cocci in chains
e. Gram+ cocci in clusters

A

b. Gram- coccobacilli

caused by Haemophilus influenzae type b (Hib) - uncommon due to vaccination, but may still be caused by untypeable strains (no vaccine)

89
Q

A patient with an untreated prolactinoma is most at risk for:
a. Cortical stroke.
b. Gastric ulcer.
c. Loss of bone mass.
d. Myocardial infarction.
e. Secondary diabetes mellitus.

A

c. Loss of bone mass.

High levels of prolactin suppress GnRH secretion from the hypothalamus leading to reduced secretion of LH —> hypogonadism and low estrogen levels

Estrogen maintains bone mass in pre-menopausal woman; low estrogen increases the risk of osteoporosis

90
Q

4yo presents with 5 day history of fever, irritability, and vomiting. PE shows bilateral conjunctival injection with no exudates. Tongue is bright red and lips are cracked. There is non-pitting edema on hands and feet. which of the following complications is most likely?
a. Aortic dissection.
b. Coronary artery aneurysm.
c. Monocular blindness.
d. Mononeuritis multiplex
e. Proliferative glomerulonephritis
f. Pulmonary cavitation.

A

b. Coronary artery aneurysm

dx = Kawasaki disease: vasculitis of medium sized arteries that affects young children (<5), most commonly Asian patients

dx based on fever for at least 5 days + 4/5 of:
1. bilateral non-exudative conjunctival injection.
2. Cervical lymphadenopathy.
3. Mucositis (“strawberry tongue”)
4. Edema or desquamation.
5. Erythematous rash on extremities that spreads to the trunk.

Coronary artery inflammation may cause aneurysm

91
Q

Complete hydatidiform moles secrete very high levels of ____

A

beta-hCG - extremely high in complete mole, normal/high in partial mole

levels must be monitored after uterine evacuation due to significant risk of malignant transformation – rising or persistently elevated levels are a concern for neoplastic conversion (invasive mole or choriocarcinoma)

92
Q

what is the mechanism of resistance to aminoglycosides?

A

Aminoglycosides interfere with the aminoacyl binding site on the 30S ribosomal subunit

resistance is via methylation of the aminoglycoside binding portion of the ribosome; can also occur via altered ribosomal proteins

93
Q

impaired transport of neutral amino acids in the small intestine and PCT would cause a deficiency of which of the following:
a. Ascorbate.
b. Niacin.
c. Pyridoxine.
d. Riboflavin.
e. Vitamin E.

A

b. Niacin

dx = Hartnup disease: AR mutation affecting neutral amino acid transporter —> decreased neutral AA, esp. tryptophan

tryptophan = essential amino acid, precursor for niacin, serotonin, and melatonin

Hartnup disease —> niacin deficiency —> pellagra-like skin eruptions (rash following sun exposure) + cerebellar ataxia in early childhood

94
Q

how does vitamin E deficiency present?

A

Rare, but causes neurologic dysfunction (ataxia, hyporeflexia, loss of sensation), as well as hemolytic anemia

95
Q

which of the following is the most appropriate treatment for Toxoplasma gondii encephalitis?
a. Amphotericin B.
b. Ampicillin.
c. Ganciclovir
d. Isoniazid + rifampin.
e. Pyrimethamine + sulfadiazine.

A

e. Pyrimethamine + sulfadiazine.

can also used pyrimethamine + clindamycin in case of sulfa allergy

96
Q

what are two abnormal cellular histological findings of the bone marrow in myelodysplastic syndrome?

A

Myelodysplastic syndrome = clonal hematopoietic neoplasm that crowds out the bone marrow and causes pancytopenia

  1. Neutrophils with hypogranular cytoplasm and bilobed nucleus.
  2. erythroid precursors with nuclear budding.
97
Q

which three antibiotics are used in broad-spectrum treatment of pelvic, inflammatory disease, and what is the coverage for each of them?

A
  1. Ceftriaxone – Neisseria gonorrhea (Gram-negative)
  2. Doxycycline – Chlamydia trachomatis (Gram-positive)
  3. metronidazole - Gardnerella vaginalis (anaerobic)
98
Q

explain why high-volume blood transfusions can cause hypercalcemia

A

prior to storage, donated blood is mixed with a solution containing citrate anticoagulant… following transfusion, citrate is rapidly metabolized to HCO3 in the liver

However, when large volumes are transfused rapidly, the excess citrate can chelate calcium in the plasma, causing hypocalcemia due to decreased serum ionized calcium concentration

99
Q

where is the most common location of aberrant electrical foci in atrial fibrillation

A

near pulmonary veins in left atrium

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