Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

STEP1 Review > UWorld Test Review 5 > Flashcards

UWorld Test Review 5 Flashcards

1
Q

almost all aminotransferases use ______ as the amino group acceptor, so that amino groups can be funneled into glutamate during protein catabolism

A

almost all aminotransferases use alpha-ketoglutarate as the amino group acceptor, so that amino groups can be funneled into glutamate during protein catabolism

glutamate is then metabolized in the liver to form urea, the primary form of nitrogen disposal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

____ is the major amino acid responsible for transferring nitrogen to the liver for disposal

A

alanine - combines with alpha-ketoglutarate to form pyruvate + glutamate (via transamination, requiring B6)

glutamate then is broken down to NH3 (ammonia), which enters urea cycle (via glutamate dehydrogenase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

the blood vessels supplying the ovary run through which ligament?

A

infundibulopelvic ligament (aka suspensory ligament) - at risk for occlusion by ovarian torsion

connects the ovaries to the pelvic sidewall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

F neonate with posterior neck mass composed of cystic spaces separated by connective tissue + bilateral non-pitting edema of hands and feet + low-set ears and high-arched palate + diminished femoral pulses = ?

A

Turner Syndrome (45,X)

neck mass = cystic hygroma, caused by obstruction of lymphatic system

non-pitting edema due to impaired lymphatic flow

diminished femoral pulses = aortic coarctation

other features/complications of TS = webbed neck, low hairline, broad chest with widely spaced nipples, horseshoe kidneys, streak ovaries, bicuspid aortic valve, aortic dissection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the cause of atrial flutter and where does it typically occur anatomically?

A

caused by a large reentrant circuit in the area between the tricuspid valve and the inferior vena cava in the right atrium (cavotricuspid isthmus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

explain why Haemophilus influenzae will only grow on sheep blood agar if cross-streaked with Staph. aureus

A

Haemophilus requires X factor (hematin) and V factor (NAD+) to grow - these are lacking in sheep blood agar

however, Staph. aureus secretes V factor (NAD+) and facilitates the release of X factor (hematin) from beta-hemolysis-induced erythrocyte lysis

this provides the needed nutrients for Haemophilus growth (“satellite phenomenon”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

patients with cleft lip and palate often have recurrent otitis media due to dysfunction of which muscle?

A

levator veli palatini - responsible for opening the eustachian tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does serology show in limited cutaneous (CREST) vs diffuse cutaneous systemic sclerosis?

A

CREST = anticentromere Abs

diffuse = anti-Scl-70 Abs (anti-topoisomerase type I)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

woman who recently gave birth presenting with decreased serum TSH and free thyroxine (T4) levels should raise suspicion of…

A

Sheehan syndrome: pituitary infarction due to ischemic necrosis (caused by systemic hypotension during delivery)

decreased TSH is important because it indicates the hypothyroidism is secondary, NOT primary (like postpartum thyroiditis - would see high TSH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

which cause of pneumonia causes hyponatremia? what will Gram stain show?

A

Legionella pneumophilia: Gram neg. bacillus, facultatively intracellular —> staining shows many neutrophils but few organisms

most common lab abnormality is hyponatremia, distinguishing from other causes of pneumonia - likely due to ADH secretion or impaired renal Na+ reabsorption

Legionnaire’s disease (via contaminated water) - presents with pneumonia (patchy infiltrates), high fever, bradycardia, neuro symptoms (confusion, headache), GI symptoms (watery diarrhea)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

patient with mono-like symptoms, but serum fails to agglutinate horse erythrocytes… most likely dx?

A

horse erythrocyte agglutination = Monospot test (for EBV)
[can also use sheep erythrocytes in Paul-Bunnell test]

in immunocompetent patients with heterophile antibody-negative mononucleosis-like syndrome, most likely dx is cytomegalovirus (CMV) infection, which may be acquired via blood transfusion

[other less common causes = HHV6, HIV, toxoplasmosis]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

From which foramina do CN V-XII exit?

A

CN V1 = superior orbital fissure
CN V2 = foramen rotundum
CN V3 = foramen ovale
CN VII, VIII = internal acoustic meatus
CN IX, X, XI = jugular foramen
CN XII = hypoglossal canal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what exits from foramen spinosum?

A

middle meningeal artery + vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

57yo F w/ cough and hemoptysis. She also reports several months of fatigue and joint pain. PE shows crusting of nasal mucosa, lung crackles, and scattered palpable purpura over the lower extremities. CXR shows bilateral, diffuse alveolar infiltrates. Labs show normocytic anemia, and urine is positive for RBC casts and proteinuria. She is positive for c-ANCA. What is the dx?

A

granulomatosis with polyangiitis: c-ANCA positive inflammatory vasculitis that primarily attacks the upper and lower respiratory tract, kidneys, and skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the 2 phases of the PPP and their purposes?

A

oxidative/irreversible phase: glucose-6-phosphate —> 6-phosphogluconate (via glucose-6-phosphate dehydrogenase, rate-limiting) —> ribulose-5-phosphate (via another dehydrogenase)… both steps produce NADPH for glutathione and cholesterol/FA synthesis

non-oxidative/reversible phase: ribulose-5-phosphate used as a substrate for nucleotide synthesis; in addition, fructose-6-phosphate is generated for glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

give an anatomical description of where the AV node is

A

interatrial septum near the opening of the coronary sinus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

which bacteria produces lecithinase?

A

lecithinase = alpha toxin, produced by Clostridium perfringens

degrades lecithin (component of phospholipid membranes) —> membrane destruction, cell death, widespread necrosis + hemolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

which 2 molecules maintain coronary autoregulation?

A

allows coronary blood flow to be primarily driven by myocardial O2 demand over a wide range of perfusion pressures (60-140mmHg)

accomplished via alterations in vascular resistance mediated by adenosine and nitric oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is first-line treatment for Phthirus pubis (human pubic louse)?

A

topical permethrin: blocks parasite Na+ conduction in nerve cell membrane channels —> paralysis and death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Vitamin K deficiency results in prolonged _____ time

A

Vitamin K activates coagulation factors II, VII, IX, and X, as well as proteins C and S

Vitamin K deficiency —> prolonged prothrombin time (PT) due to deficiency of factor VIIa (activated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the most important environmental risk factor for lung cancer, aside from cigarette smoke?

A

radon gas - found in soil and groundwater, emits highly ionizing alpha radiation —> DNA damage to respiratory tract epithelium when inhaled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

a patient with chronic HF w/ reduced ejection fraction is treated with a drug that works by inhibiting a metalloprotease to prolong the action of endogenous polypeptides… what drug is this?

A

neprilysin inhibitors (ex, sacubitril) —> enhanced activity of ANP and BNP (endogenous polypeptides)

[neprilysin = metalloprotease which breaks down ANP/BNP]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

explain how the following change with aging:
a. lung compliance
b. total respiratory system compliance
c. physiologic dead space

A

a. lung compliance - INCREASES due to loss of elastin (resembles mild emphysema)

b. total respiratory system compliance - DECREASES bc increased stiffness of chest wall dominates over increased compliance

c. physiologic dead space - INCREASES due to elastin degeneration + capillary dropout

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what makes Haemophilus influenzae type b (Hib) more invasive than other strains?

A

polyribosylribitol phosphate (PRP) capsule - inhibits complement mediated phagocytosis

[serotypes a-f are encapsulated, while nontypeable strains do not have a capsule - why they are nontypeable!!]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

on which cells are CD15 and CD16 found, respectively?

A

CD15 = granulocytes, also present on Reed-Sternberg cells (Hodgkin’s lymphoma)

CD16 = low affinity Fc receptor on NK cells, neutrophils, and macrophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what murmur does a ventricular septal defect cause? include location

A

holosystolic murmur at the lower left sternal border (louder with small VSD due to more turbulence)

small VSD will cause increase in RV SpO2, while large VSD allows for equalization between chamber pressures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

bifid carotid pulse with brisk upstroke =

A

hypertrophic cardiomyopathy - dynamic LV outflow tract obstruction during systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

fixed splitting of S2 =

A

atrial septal defect (ASD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

overlying skin retractions (puckering) caused by invasive breast carcinoma are due to involvement of…..

A

suspensory ligaments (Cooper ligaments) - extend out towards skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is heard on cardiac auscultation in a patient with bicuspid aortic valve vs pulmonic stenosis?

A

bicuspid aortic valve - narrowed or paradoxical splitting of S2

pulmonic stenosis - widened splitting of S2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

horseshoe kidney is due to fusion of:
a. mesonephric duct
b. mesonephros
c. metanephros
d. pronephros
e. urogenital ridge

A

c. metanephros

pronephros = rudimentary nephric system, degenerates early in gestation

mesonephros mostly degenerates, except mesonephric duct - persists as ureteric bud

urogenital ridge - gives rise to nephric system + gonads/reproductive tract + and real cortex + kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

absence of CD40 ligand on CD4+ T cells =

A

hyper-IgM syndrome: CD4+ T cells cannot stimulate B cells to class switch/ differentiate into plasma and memory cells —> sinopulmonary infections, GI infections, failure to thrive (increased metabolic demands from being sick)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

HIV-1 vs HIV-2

A

HIV-1: worldwide, high viral load, 7-10 years progression to AIDs

HIV-2: West Africa, low viral load (lower viremia), 10-25 years progression to AIDs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

describe the genital ulcers caused by:
a. Haemophilus ducreyi
b. Klebsiella granulomatis
c. Chlamydia trachomatis (L serovars)

A

a. Haemophilus ducreyi: chancroid - deep, purulent, painful, progress from papule to ulcer, >1 present

b. Klebsiella granulomatis: granuloma inguinale - painless, red, progressive, without lymphadenopathy

c. Chlamydia trachomatis (L serovars): lymphogranuloma venereum - painless, but spreads to regional lymph nodes and causes painful lymphadenitis; rare in US, occurs in tropical/subtropical regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

78yo M w/ progressive dyspnea, generalized weakness, palpitations, and tingling/numbness in lower limbs may have a deficiency of which vitamin?

A

thiamine (B1): necessary for decarboxylation of alpha-keto acids (carbohydrate metabolism)

dx: beriberi: peripheral neuropathy + heart failure
[dry = just neuropathy, wet = neuropathy + cardiac]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what is the most common site of blunt aortic injury (such as by high-speed motor accident), and why?

A

aortic isthmus, just distal to the attachment of the ligamentum arteriosum

this section is relatively immobile compared to adjacent descending aorta - rapid deceleration can cause it to tear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

name 3 cancers that spread hematogenously

A
  1. sarcomas
  2. renal cell carcinoma
  3. hepatocellular carcinoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

which of the following is caused by a GOF mutation of a non-receptor tyrosine kinase protein in hematopoietic cells, leading to persistent activation of STAT proteins?
a. acute promyelocytic leukemia
b. chronic lymphocytic leukemia
c. high-grade non-Hodgkin lymphoma
d. mantle cell lymphoma
e. primary myelofibrosis

A

e. primary myelofibrosis: mutation in JAK2 (Janus kinase 2, non-receptor cytoplasmic tyrosine kinase) —> overactive tyrosine phosphorylation and activation of STAT pathway

[same mutation causes essential thrombocytosis and polycythemia vera]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

child with hoarseness, respiratory distress, and polypoid growths in clusters on true vocal chords =

A

dx = recurrent respiratory papillomatosis: caused by HPV serotypes 6 and 11

transmitted via sexual contact or reactivation of vertical transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

which hormone inhibits lactation during pregnancy despite high prolactin levels?

A

progesterone - drop following delivery allows lactation to occur

41
Q

what are the 3 actions of the recurrent branch of the median nerve?

A
  1. thumb abduction (abductor pollicis brevis)
  2. thumb flexion (flexor pollicis brevis)
  3. thumb opposition (opponens pollicis)

may be injured via lunate dislocation !

42
Q

recurrent focal impaired awareness seizures preceded by uneasy epigastric sensation or olfactory hallucination are characteristic of…

A

medial temporal lobe epilepsy - caused by hippocampal sclerosis, associated with childhood febrile illness

43
Q

what are the 2 metabolic fates of pyruvate? include enzymes required and end products

A
  1. via pyruvate carboxylase —> oxaloacetate, substrate for gluconeogenesis
  2. via pyruvate dehydrogenase —> acetyl-CoA, which enters TCA for ATP production
44
Q

16yo M presents with long/narrow face, prominent forehead/chin, large testes, hyperlaxity of the hand joints + developmental delay/ intellectual disability + ADHD/autism =

A

fragile X syndrome: X-linked TNR of CGG in FMR1 gene —> hypermethylation

45
Q

describe how the concentrations of each of the following change along the length of the proximal tubule:
a. creatinine
b. bicarbonate
c. urea
d. glucose
e. amino acids

A

creatinine: freely filtered + secreted, NOT reabsorbed —> rapidly increasing concentration in tubular fluid

urea: freely filtered, poorly reabsorbed —> steady increase in concentration

bicarbonate: actively reabsorbed (via carbonic anhydrase) —> steady decrease in concentration

glucose, amino acids: avidly reabsorbed —> rapidly decreasing concentration

CUBAG, or Creating Unnecessary Bigotry Gets Annoying

46
Q

most dangerous adverse effect of amphotericin B

A

nephrotoxicity - due to decrease in GFR and direct toxic effects on tubular epithelium

watch out for anemia (decreased EPO production) and electrolyte imbalances (hypokalemia), which may cause weakness and arrhythmias

47
Q

which neurons of the CNS release serotonin? where are they located?

A

Raphe nuclei - disbursed throughout brainstem, axons project widely in CNS

[if Ralphe had more serotonin, maybe he would be happier!]

48
Q

which neurons of the CNS produce norepinephrine? where are they located?

A

Locus ceruleus - located in dorsal pons

[when LOCUS descended on the city, everyone got STRESSED (NE!) and ran]

49
Q

most common cause of eosinophilic meningitis

A

Angiostrongylus cantonensis: helminth in Southeast Asia and Pacific Islands

transmitted via consumption of contaminated mollusks or snails

50
Q

what does imaging show in sporadic encephalitis caused by Herpes virus type 1?

A

inflammation/edema of temporal lobe

51
Q

GABA agonist used for anesthesia induction that is hemodynamically stable

A

etomidate: provides sedation and amnesia, does not cause changes in HR/BP/CO

however, inhibits cortisol synthesis (adrenocortical suppression) - avoid in shock patients

52
Q

renal metabolism of which amino acid is most important for maximizing acid excretion?

A

glutamine - metabolism generates ammonium and bicarbonate

bicarbonate is used to buffer acids in blood

53
Q

which antiarrhythmic preferentially binds to rapidly depolarizing myocardial fibers, with minimal effect on normal ventricular myocardium?
a. adenosine
b. diltiazem
c. ibutilide
d. lidocaine
e. procainamide

A

lidocaine: class IB, weakest Na+ channel blockers (dissociate the fastest) - bind inactivated state, dissociate rapidly so they have negligible effect on QRS

ischemic myocardium has less negative resting membrane potential, which delays recovery of Na+ channels from inactivated to resting… this allows for increased binding of IB agents

therefore, Class IB anti-arrhythmics (lidocaine) are efficacious in inhibiting ischemia-induced ventricular arrhythmias

54
Q

when would you use procainamide vs lidocaine?

A

procainamide = Class IA anti-arrhythmic —> binds Na+ channels in open state, specific for suppressing arrhythmias from areas of normal automaticity

lidocaine = Class IB anti-arrhythmic —> binds inactivated Na+ channels, specific for suppressing arrhythmias from areas of ischemic myocardium (having higher resting membrane potential)

55
Q

what is the treatment for warfarin vs heparin overdose?

A

warfarin overdose - Vitamin K (takes days) + fresh frozen plasma (contains all clotting factors)

heparin overdose - protamine (binds heparin, forming inactive complex)

56
Q

why is fresh frozen plasma but not cryoprecipitate effective in treating warfarin overdose?

A

fresh frozen plasma (FFP): contains all clotting factors

cryoprecipitate: precipitate obtained from FFP by centrifugation, contains factor VIII, factor XIII, vWF, and fibrinogen - does not replenish Vitamin K factors (II, VII, IX, X)

57
Q

for which hematological disorders is desmopressin used to treat?

A

increases plasma levels of vWF and factor VIII —> treats hemophilia A (VIII deficiency) and von Willebrand disease

58
Q

which of the following would be the most appropriate choice in an elderly patient?
a. chlorpheniramine
b. diphenhydramine
c. hydroxyzine
d. loratadine
e. promethazine

A

d. loratadine = 2nd gen. antihistamine

do not cause antimuscarinic/antiserotonergic/anti-alpha adrenergic side effects, less lipophilic and do not cross BBB (non-sedative)

[all other options are first gen.]

59
Q

triad of fibrous dysplasia + endocrine abnormalities + cafe-au-lait spots =

A

McCune-Albright syndrome: mutation in GNAS gene (encodes alpha subunit of G protein) —> constitutive Gs activation and hormone overproduction

60
Q

which symptom of organophosphate poisoning will not resolve with atropine administration, and which therapy needs to be added to solve this?

A

organophosphates inhibit cholinesterase in both muscarinic + nicotinic synapses

atropine is a competitive inhibitor of ACh at muscarinic synapses only —> will NOT treat MUSCLE WEAKNESS

pralidoxime is a cholinesterase-reactivating agent —> treats muscarinic + nicotinic

61
Q

Pt presents w/ R leg pain, fever, confusion. Pt was injured while operating a motorized watercraft in Florida 2 days ago. Temp 102 (38.9), BP 90/50, pulse 120/min. PE shows a small laceration on the right foot w/ surrounding edema, erythema, and hemorrhagic bullae. Leukocyte count and lactic acid are elevated. Blood cultures reveal curved gram-negative rod. Which of the following is the greatest risk factor for this patient’s infection?
a. condition causing iron overload
b. exposure to infected rodent urine
c. lack of booster immunization

A

dx = Vibrio vulnificus: curved Gram(-) rod, lives in salt water, ingested via raw oysters or wound infection; higher risk w/ condition causing iron overload (promotes growth) —> rapidly progressive septicemia and cellulitis (w/ hemorrhagic bullae and necrotizing fasciitis)

b. exposure to infected rodent urine = Leptospira
c. lack of booster immunization = Clostridium tetani

62
Q

how would you differentiate immune thrombocytopenia from von Willebrand factor deficiency?

A

both will have normal PT, normal PTT, and increased bleeding time

immune thrombocytopenia: decreased platelet count, produces episodic mucocutaneous bleeding (petechiae, purpura, epistaxis), but NOT chronic

vWF deficiency: normal platelet count, lifelong history of mucosal bleeding (gingival, epistaxis, menorrhagia)

63
Q

what does vWF bind to promote platelet adhesion?

A

binds/crosslinks platelet glycoproteins (GpIb) with exposed collagen underneath damaged endothelium

64
Q

Pt is a 42yo M, presents w/ recurrent syncope that is preceded by palpitations. PMH includes back injury, for which they take methadone. BP is 120/70 supine and 125/75 standing. What is the most likely cause of syncope in this patient?

A

QT-prolongation due to methadone - common adverse effect due to delayed rectifier K+ current… risk of triggering torsade de pointes

other drug causes: macrolides, fluoroquinolones, antiemetics, azoles, antipsychotics/TCAs/SSRIs, methadone/oxycodone, Class IA and III anti-arrhythmic

congenital causes: Romano-Ward (AD), Jervell & Lange-Nielsen (AR)

65
Q

serious side effects of statins include… (2)

A
  1. myopathy
  2. hepatitis - monitor liver transaminase levels
66
Q

29yo F presents w/ high fever and diffuse rash which began 5 days ago. She has also experienced headache, retroorbital pain, and joint/muscle pain. Pt returned from Brazil 10 days ago. PE shows diffuse maculopapular rash and scattered petechiae over her extremities. Labs show thrombocytopenia. What is the causative pathogen?

A

dengue (Flavivirus): transmitted via Aedes mosquitos, prominent in tropical/subtropical regions of Asia and South America

67
Q

which infections are transmitted via Aedes mosquitos? (4)

A
  1. dengue (Flavivirus)
  2. yellow fever
  3. Zika
  4. chikungunya

simultaneous outbreaks are common during rainy season

68
Q

when is finger clubbing observed?

A

cardiopulmonary diseases in which hypoxic-inflammatory pathways are activated —> release of growth factors (VEGF)

including: lung adenocarcinoma (most common in adults), bronchiectasis (chronic infection), cyanotic heart defects

69
Q

in which patients are gallstones most likely?

A

“fat, fertile, female, forty”

pregnancy/OC predisposes to gallstone formation due to estrogen-induced cholesterol hyper-secretion and progesterone induced hypomotility

70
Q

which of the following can improve survival in patients with congestive heart failure and reduced LV ejection fraction?
a. acetazolamide
b. furosemide
c. hydrochlorothiazide
d. spironolactone
e. triamterene

A

d. spironolactone (mineralocorticoid receptor antagonists)

note - should not be used in patients with hyperkalemia or renal failure (K+ sparing)

71
Q

polymyositis vs polymyalgia rheumatica

A

polymyositis: symmetric proximal muscle weakness, elevated CK and ANA Abs, biopsy shows endomysial mononuclear infiltrate w/ patchy necrosis

polymyalgia rheumatica: myalgias (NOT weakness) of shoulder and pelvic girdle muscles, often w/ systemic symptoms (fever, weight loss), patients >50

72
Q

during orchiopexy (fixation of undescended testis in the scrotum), the testis are pulled through the superficial inguinal ring, a physiologic opening in the…

A

external oblique aponeurosis

73
Q

for which 4 enzymes is thiamine (B1) a cofactor?

A
  1. pyruvate dehydrogenase: converts pyruvate into acetyl-CoA
  2. alpha-ketoglutarate dehydrogenase: TCA cycle
  3. alpha-ketoacid dehydrogenase: catabolism of branch-chained amino acids (leucine, isoleucine, valine)
  4. transketolase: converts ribulose-5-phosphate to glyceraldehyde-3-phosphate (PPP)
74
Q

what is the cause of posterior urethral valves?

A

persistence of urogenital membrane (incomplete canalization) —> bladder outlet obstruction, vesicoureteral reflux, hydronephrosis

75
Q

a single temporal lobe abscess is usually a result of otitis media that spread to the ______, while frontal lobe abscess is usually due to ______ or _____ sinusitis

A

a single temporal lobe abscess is usually a result of otitis media that spread to the mastoid air cells, while frontal lobe abscess is usually due to ethmoid or frontal sinusitis

76
Q

what are 2 clinical uses of adenosine

A
  1. vasodilator in chemical cardiac stress tests
  2. fast acting anti-arrhythmic for stopping acute supra-ventricular tachycardias

very short half-life

77
Q

which 5 drugs are associated with drug-induced lupus erythematosus?

A
  1. hydralazine
  2. procainamide
  3. isoniazid
  4. minocycline
  5. quinidine

will present with new onset lupus symptoms, ANA and anti-histone antibodies (NOT anti-dsDNA like in SLE)

78
Q

which 2 types of anti-diabetic medications promote weight loss?

A
  1. GLP-1 agonists
  2. SGLT-2 inhibitors
79
Q

for which 3 enzymes is tetrahydrobiopterin (BH4) an essential cofactor?

A
  1. phenylalanine hydroxylase: converts phenylalanine to tyrosine
  2. tyrosine hydroxylase: converts tyrosine to L-dopa
  3. tryptophan hydroxylase: converts tryptophan to serotonin
80
Q

which 3 medications impair folate metabolism, and therefore are associated with neural tube defects?

A
  1. valproate
  2. methotrexate
  3. trimethoprim-sulfamethoxazole (TMP-SMX)
81
Q

with what is subacute bacterial endocarditis (SBE) caused by S. gallolyticus (S. bovis) vs S. viridans associated?

A

S. gallolyticus (S. bovis): normal flora of colon, bacteremia associated with colon cancer, also most cases of SBE occur in patients without pre-existing valvular abnormality

S. viridans: SBE following dental work

82
Q

how do patients w/ restrictive vs obstructive lung disease compensate for the increased work of breathing?

A

restrictive —> rapid, shallow breathing (keep tidal volume low)

obstructive —> slow, deep breathing (keep respiratory rate low)

83
Q

what are the 3 stages of acute tubular necrosis (ATN)?

A

may occur due to ischemia caused by hypotension (such as hemorrhage, for example)

  1. initiation (24-36h): ischemic or toxic insult occurs
  2. maintenance (1-2 weeks): tubular damage causes oliguria, fluid overload, electrolyte abnormalities, “muddy” casts
  3. recovery: re-epithelialization of tubules, GFR recovers, transient polyuria and loss of electrolytes
84
Q

AD mutation in TTN gene encoding for titin protein =

A

familial dilated cardiomyopathy

titin = sarcomere protein, anchors beta-myosin heavy chain to Z-discs

[acquired causes = viral infection, alcohol, cocaine, infiltrative disease]

85
Q

name the cancers with the tumor marker:
a. alpha-fetoprotein (2)
b. beta-hCG (3)
c. cancer antigen 125 (CA-125)
d. estrogen
e. lactate dehydrogenase

A

a. alpha-fetoprotein: hepatocellular carcinoma + ovarian germ cell tumors

b. beta-hCG: hydatidiform mole, choriocarcinoma, dysgerminomas

c. cancer antigen 125 (CA-125): epithelial ovarian cancer

d. estrogen: granulosa cell tumors

e. lactate dehydrogenase: dysgerminomas

86
Q

pt returning from South Africa w/ high fever, headache, severe myalgia, and joint pain =

A

dengue (Flavivirus infection): transmitted via Aedes mosquito, common in South America

primary infection causes breakbone fever, secondary infection (w/ different viral serotype) causes dengue shock syndrome (hemorrhagic, stupor)

[4 dengue virus serotypes, cross-reactive antibodies with repeat infection by different serotypes cause worse disease]

87
Q

crescent-shaped intracellular organism causing congenital triad of chorioretinitis + diffuse intracranial calcifications + hydrocephalus

A

congenital toxoplasmosis (Toxoplasma gondii)

88
Q

what is the order of mutation of the following genes in the adenoma-to-carcinoma sequence?

K-RAS, APC, p53, DCC

A

APC tumor suppressor gene is typical first mutation

followed by K-RAS + DCC (deleted in colon cancer) + p53

[note K-RAS and DCC mutations are anti-apoptotic, and typically occur in larger adenomas]

89
Q

what is the treatment for scabies? (2)

A
  1. topical permethrin: blocks voltage-gated Na+ channels
  2. oral ivermectin: blocks Cl- channels, alternative medication or used in combination for crusted (sever) scabies
90
Q

what is topical mupirocin used to treat?

A

impetigo caused by Staph. aureus or Strep. pyogenes

91
Q

what is the clinical use of sevelamer in chronic kidney disease?

A

sevelamer: non-absorbable anion-exchange resin that binds intestinal phosphate to reduce absorption

used if dietary phosphate restriction is not sufficient

92
Q

which 4 bacteria most commonly cause pulmonary exacerbations in patients with cystic fibrosis?

A
  1. Staph. aureus
  2. Pseudomonas aeruginosa
  3. nontypeable Haemophilus influenzae
  4. Burkholderia cepacia complex (Gram neg.)
93
Q

which classes of antibodies have hinge regions?

A

IgG, IgD, IgA

hinge regions increase avidity by providing flexibility to reach multiple epitopes on an antigen

[avidity proportional to number of Fab-antigen interactions]

94
Q

what is the most common CFTR gene mutation causing cystic fibrosis?

A

3-base pair deletion of phenylalanine at position 508 —> impaired post-translational processing

transport protein is made, but targeted for proteosomal degradation instead of surface

95
Q

administration of which ion improves neuron survival in glutamate toxicity?

A

glutamate NMDA receptor is normally occupied by magnesium in resting state

Mg2+ is displaced by either glutamate binding or loss of negative potential (in dying neuron, this can be caused by loss of ATP-dependent Na/K gradient)

giving magnesium can block the NMDA channel, decreasing influx of Ca2+ and Na+ —> inhibited glutamate-mediated depolarization

96
Q

what is the primary anti-ischemic effect of nitrates?

A

VENOdilation —> decreased LV end-diastolic volume and wall stress, decreased myocardial oxygen demand

97
Q

what does histology of pancreatic islets show in Type 1 vs Type 2 diabetes?

A

Type 1: islet leukocytic infiltration (AUTOIMMUNE)

Type 2: islet amyloid deposition

98
Q

contrast the MOA of zileuton vs montelukast

A

zileuton: 5-lipoxygenase enzyme inhibitor, reduces production of leukotrienes

montelukast: leukotriene receptor antagonist

99
Q

which arteries are derived from each of the pharyngeal arches?

A
  1. maxillary artery (CN V)
  2. stapedial artery (CN VII)
  3. common carotid, proximal internal carotid (CN IX)
  4. true aortic arch, subclavian arteries (CN X - superior laryngeal)
  5. obliterated
  6. pulmonary arteries, ductus arteriosus (CN X - recurrent laryngeal)

STEP1 Review (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions