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Qbank Flashcards

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USMLE® Step 1 flashcards
1
Q

LM, EM, IF findings in acute poststrep glomerulonephritis? Complement levels?

A
  • LM: hypercellular glomeruli, enlarged throughout. Due to leukocyte infiltration, mesangial/endothelial proliferation
  • IF: granular apperance
  • EM: subepithelial immune complex humps
  • low C3
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2
Q

What is winter’s formula?

A

Pco2=1.5[HCO3-] +8 plus/minus 2

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3
Q

What is myc protein?

A

Transcriptional factor

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4
Q

what is k-RAS protein?

A

GTPase that participates in cellular signaling. Oncogene, associated with colon, lung and pancreatic cancer

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5
Q

What is Beck’s triad in cardiac tamponade?

A
  • hypotension, distended neck veins (increased JVP), distant heart sounds
  • can also find pulses paradoxes, high HR
  • can be caused by serous viral pericarditis, acute pericardial effusion
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6
Q

Drugs that can cause lupus-symptoms?

A
  • procainamide
  • hydralazine
  • isoniazid
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7
Q

most frequent side effects for verapamil?

A

-constipation, gingival hyperplasia, negative inotropy

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8
Q

Describe the common cardiac defect seen in Down syndrome and the mechanism of defect?

A
  • Ostium primum ASD: due to incomplete fusion of septum premium with endocardial cushions
  • also can cause regurgitant AV valves
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9
Q

define absolute risk reduction

A

ARR=event rate in control group-event rate in treatment group

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10
Q

Patients with familial retinoblastoma have increased risk of developing what secondary tumors?

A
  • osteosarcomas

- sarcomas in general, but esp. osteosarcoma

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11
Q

List E. Coli virulence factors and the diseases they cause.

A
  • fimbriae: cystitis, pyelonephritis
  • K capsule: pneumonia, neonatal meningitis
  • LPS endotoxin: septic shock
  • enterotoxin: gastroenteritis
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12
Q

Why does silicosis predispose to TB infection?

A
  • silica may disrupt phagolysosomes and impair macrophages

- also silicosis increases risk of bronchogenic carcinoma

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13
Q

Major side effects of metformin

A
  • Gi upset
  • lactic acidosis
  • contraindicated in renal failure (Cr>1.5), hepatic dysfunction, alcoholics, CHF
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14
Q

Sore with central black echar surrounded by edema. Chains of large gram positive rods.

A

Bacillis anthracis

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15
Q

Which cardiac arrhythmia drug has lower incidence of inducing torsades de pointes than other QT prolonging drugs?

A
  • amiodarone

- among class 1A and III drugs that prolong QT interval

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16
Q

Management of hyperpyrexia?

A
  • body temperature over 40 C. First must cool the body, can use cool blankets
  • then give antipyretics such as acetominophen
  • can occur with malignant hyperthermia, neurleptic malignant syndrome, heat stroke, severe infection
  • can cause brain damage
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17
Q

Differentiate between postpartum “blues”, depression, and psychosis.

A
  • blues: starts 2-3 days after delivery, resolves in 10 days
  • depression: starts within 4 weeks of delivery, lasts 2-12 months
  • pyschosis: delusions, hallucinations, and thoughts of harming self or baby
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18
Q

Derivatives of the first branchial arch

A

Nerve: V2, V3 (chew)

  • meckel cartilage, mandible, malleus, incus, sphheno-mandibular ligament
  • muscles of mastication: temporalis, master, pterygoids, mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini
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19
Q

where is area postrema located?

A
  • dorsal medulla near 4th ventricle

- chemoreceptor trigger zone triggers vomitting

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20
Q

What is the most abundant amino acid in collagen?

A
  • glycine

- then proline and lysine are abundant as well

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21
Q

First step in screening for malabsorption?

A

-Sudan oil stain of stool to confirm fat>7g/day excretion

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22
Q

Products of HIV genes gag, pol, env?

A
  • gag: p24 and p7 nucleocapsid proteins
  • env: gp120 and p41 envelop protiens
  • pol: reverse transcriptase, protease, integrase
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23
Q

Distinguish between Souther, Northern, Western, southwestern blot, and ELISA.

A

General: Sample is cleaved, electrophoreses on gel, and transferred to filter. Filter exposed to probe.

  • southern blot: detects DNA using radiolabeled DNA probe
  • northern blot: detects RNA
  • western blot: labeled antibody used to bind and detect protein
  • southwestern blot: identifies DNA binding proteins, e.g. transcription factors
  • ELISA: detect antigen or antibody in patient’s blood sample
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24
Q

Causes of sudden cardiac death.

A
  • most (70%) due to CAD. The most common cause of death in this case is an acute plaque change leading to thrombosis and acute myocardial ischemia. This may precipitate ventricular fibrillation, the most common arrhythmia in pre-hospital stage and common cause of death
  • other causes: cardiomyopathy, hereditary channelopathies
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25
Q

List order of most common location to less common for development of atherosclerotic plaques .

A

Tends to develop in large elastic arteries and large to medium muscular arteries

  1. abdominal aorta
  2. coronary artery
  3. popliteal artery
  4. carotid artery
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26
Q

How to treat cardiotoxicity/QT prolongation induced by TCAs?

A

give sodium bicarbonate

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27
Q

How is schistosoma acquired? What animal?

A
  • from infected freshwater
  • snails
  • the larva penetrate human skin go to liver, grow into worms. worms invade blood, hang onto blood vessels, release eggs.
  • eggs cause Th2 granulomatous reaction
  • can cause hepatic and urinary schistosomiasis.
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28
Q

List the rapid acting, intermediate acting, and long acting insulins.

A
  • rapid acting: insulin aspart, lispro, glulisine
  • intermediate: NPH insulin
  • long acting: glargine, detemir
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29
Q

What is the mechanism for resistance to ceftriaxone?

A

-structural changes in penicillin binding proteins (transpeptidases)

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30
Q

List the toxin and mechanism of action for:

  • C. diphtheriae
  • Shigella
  • Pseudomonas
  • C. perfringens
  • Strep pyogenes
A
  • C. diphtheriae: AB exotoxin. B binds and induces endocytosis, and A induces ADP ribosylation, causing inactivating elongation factor
  • Shigella: inactivates 60S ribosome by removing adenine from rRNA
  • Pseudomonas: inactivates EF2
  • C. perfringens: phopholipase, degrades cell membranes
  • Strep pyogenes: Streptolysin O degrades cell membrane. Exotoxin A binds MHC II and TCR outside of antigen binding site, causes lots of release of Il1,2, IFNy, TNFa–> shock
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31
Q

What is LaPlace’s law for pressure required to keep a sphere distended?

A

P= 2T/r
T=surface tension
r=radius, smaller spheres have more pressure and tendency to collapse

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32
Q

Mechanism of C. Difficil pathogenicity?

A
  • Enterotoxin A binds to brush border of gut

- Toxin B causes cytoskeletal disruption via actin depolymerization

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33
Q

Symptoms of serotonin syndrome and treatment.

A
  • hyperthermia, confusion, myoclonus, CV instability, flushing, diarrhea, seizures, hyperreflexia, tachycardia, HTN, diaphoresis
  • Rx with cyproheptadine (5HT2 antagonist)
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34
Q

Which opioid analgesic has partial agonist and weak antagonist activity?

A

Pentazocine

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35
Q

Post traumatic stress disorder vs. acute stress disorder?

A

PTSD>4weeks

acute stress syndrome: 2days-4weeks

36
Q

Criteria for depression

A

2 or more weeks, 5+ of: SIG E CAPS

  • sleep disturbance
  • interest loss
  • guilt
  • energy loss
  • concentration problems
  • appetite changes
  • psychomotor retardation/agitation
  • suicidal ideations
37
Q

Schizophrenia vs. schizophreniform vs schizoaffective disorder

A
  • schizophreniform: 1-6months
  • schizophrenia: >6months
  • schizoaffective: >2weeks, psychosis with mood disorder. Mood disorder only appears with psychosis
38
Q

Which segment of Renal tubules have lowest tubular osmolality?

A

-distal convuluting tubule. Impermeable to water. “diluting segment)

39
Q

intellectual disability, growth retardation, seizures, hypo pigmentation of skin, eyes, catecholamine brain nuclei. What enzyme is deficient?

A

phenylalanine hydroxylase

-disease is PKU. have musty body odor

40
Q

Which bacteria have a non polysaccharide capsule?

A
  • bacillus anthracis

- polypeptide capsule with D-glutamate

41
Q

Patient with bronchial asthma, recurrent pulmonary infiltrates, eosinophilia. Bronchiectasis.

A

-Allergic bronchopulmonary aspergillosis (ABPA). Can occur in asthma and CF patients. May cause bronchiectasis and eosinophilia

42
Q

Where would you place filter to prevent DVT from embolizing to lungs?

A

-IVC

43
Q

Type of immune reaction for acute transplant rejection.

A

-Cell or humoral mediated
-cell mediated: CD8+ T cells activated against donor MHCs (type 4)
-humoral: antibodies develop after transplant (type 2)
takes place weeks to months after

44
Q

hyperacute transplant rejection pathogenesis

A

-pre-existing recipient antibodies react to donor antigens (Type II HSR)

45
Q

Side effects of digoxin

A
  • cholinergic: nausea, vomiting, diarrhea, blurry yellow vision, arrythmias, AV block
  • hyperkalemia: poor prognosis
  • while spironolactone causes hyperkalemia, it doesn’t cause the cholinergic symptoms
46
Q

Gram +, catalase negative, coagulase negative. PYR +

A

Strep pyogenes

47
Q

Necrotizing fasciitis -microbial ddx?

A
  • staph aureus
  • strep pyogenes
  • C. perfringens: double zone of hemolysis
48
Q

Findings and pathogenesis of Fragile X syndrome

A
  • Findings: macroorchidism, long face, large ears, autism, MVP
  • trinucleotide repeat CGG. Increased number of repeats causes hypermethylation of FMR1 gene leading to gene inactivation
49
Q

Which drug treatment for TB requires acidic environment?

A

pyrazinamide.

50
Q

List the adverse effects (potentially lethal) associated with the following drugs:

  • Cocaine
  • heroin/opioids
  • PCP
  • amphetamines
A
  • Cocaine: MI, ischemic events
  • heroin/opioids: respiratory depression
  • PCP: violent behavior, trauma. Also causes loss of coordination, nystagmus, acute brain syndrome (disorientation, poor judgement, memory loss)
  • amphetamines: seizures and strokes. Also can occur with cocaine
51
Q

Thiamine is a cofactor for which enzymes? How can thiamine deficiency be diagnosed?

A 
Cofactor for
-pyruvate dehydrogenase
-a-ketoglutarate dehydrogenase
-transketolase (HMP shunt)
-branched chain ketoacid dehydrogenase
Diagnosed by:
-increase RBC transketolase activity following Vitamin B1 (thiamine) administration
52
Q

List the enzyme deficiencies and their substrates and products in Congenital Adrenal Hyperplasia.

A
  1. 21a-hydroxylase: progesterone to 11-deoxycorticosterone
    - increase androgens
    - decrease cortisol and aldosterone
  2. 11b-hydroxylase: 11-deoxycorticosteone to corticosterone
    - increase androgens and mineralocorticoid
    - decreased cortisol, aldosterone
  3. 17a-hydroxylase: pregnenolone to 17-OH-pregnenolone. And progesterone to 17-OHprogesterone
    - increased MR
    - decreased cortisol, androgens
53
Q

Structure of MHC class I contains? what cells express MCH class I?

A
  • heavy chain and b2-microglobulin

- all nucleated cells have MHC I. Not expressed on RBCs

54
Q

If given amino acid with pka values, when do protons dissociate from the amino acid?

A

When pH exceeds the pKa. In example, with COOH group with pka 2.2, NH3 group with pka 9.2, 10.2, at physiologic pH of 7.4, the groups would be in the state: COO-, NH3+, NH3+, Giving total charge of +1 to the amino acid.

55
Q

Describe series of gene mutations associated with colon cancer from adenoma to carcinoma.

A
  1. mutation of APC tumor suppressor gene–>formation of small adenoma
  2. mutation of K-ras protooncogene –>growth of adenoma
  3. mutation of p53 and DCC–>malignant transformation
56
Q

side effects of nitrates?

A

-headaches and flushing due to vasodilatory effects are most common

57
Q

Horseshoe kidneys are trapped under which artery?

A

IMA, as they ascend from the pelvis during fetal development

58
Q

What is found in maternal serum during a positive screen for Down syndrome?

A

Called the quadruple screen

  • low AFP and uncongugated estriol levels
  • high b-HcG and inhibin A
59
Q

What drug can be used in patients with mild von Willebrand’s disease?

A

Desmopressin. Induces release of vWF from endothelial cells

60
Q

Describe histological changes after ischemic brain damage.

A 
12-48 hrs: red neurons
24-72 hrs: necrosis and neutrophils
3-5days: macrophages (microglia)
1-2 weeks: reactive gliosis+vascular proliferation
>2 weeks glial scar
61
Q

Circulating erythrocytes are unable to synthesize heme despite containing enzymes that participate in heme synthesis because they lack?

A
  • they lack mitochondria

- maturing RBCs lose it

62
Q

How to tell difference between septic arthritis by gonococcal vs gout/pseudogout by WBC count?

A

-gout/pseudogout wbc

63
Q

What phases are oocytes arrested in?

A
  • primary oocytes arrested in Prophase I of meiosis

- before ovulation, oocytes resume differentiation and are arrested in metaphase II

64
Q

Enlarged, rounded cells with peripherally located nuclei and dispersed finely granular Nissl substances seen in body of neuron. What is happening?

A

Axonal reaction in Wallerian degeneration. Changes reflect increase in protein synthesis for axonal repair

65
Q

cerebellar Ataxia, superficial blanching nests of distended capillaries on sun exposed skin, and increased risk of sinopulmonary infections. What disease?

A

-ataxia telengiectasia. Autosomal recessive mutation in ATM gene, which is responsible for DNA break repair.

66
Q

Henoch Scholein pupura presentation

A
  • affects boys 2-10 years old, after URI
  • GI: abdominal pain
  • renal: IgA nephropathy
  • skin: palpable purpura-leukocytoclasis of cutaneous vessels
  • joints: arthralgias
67
Q

Baby born with urine discharge from umbilicus?

A

-Patent urachus: yolk sac forms the allantois, which becomes urachus, a duct between fetal bladder and yolk sac

68
Q

Impaired ability to metabolize very long chain fatty acids (VLCFA), defect localized to? Impaired ability to metabolize long-chain fatty acids (LCFA), defect localized to?

A
  • peroxisomes: VLCFA

- mitochondria: LCFA

69
Q

how do you calculate number needed to harm?

A

NNH=1/AR
-AR=attributable risk= a/(a+b)-c/(c+d)
which is the difference in risk between the exposed and the unexposed groups

70
Q

aggressive treatment with Osmotic diuretics such as mannitol can cause what type of adverse effect?

A

A patient presenting after trauma may be treated with mannitol to reduce cerebral edema

  • pulmonary edema
  • common side effects: headache, nausea, vomiting
71
Q

Describe relationship between Cr levels in blood and GFR.

A
  • non linear
  • Cr relatively normal until GFR drops below 50 mL/min, then Cr starts to increase dramatically for small decreases in GFR
72
Q

describe presentation of reactive arthritis

A
  • preceding GU or GI infection
  • monoarticular/oligoarticular asymmetrical joint pain
  • uveitis/acute conjunctivitis
  • urethritis
  • skin: keratoderma blennorrhagium (hyperkeratotic vesicles on palms and soles)
73
Q

Describe presentation of scurvy.

A

-painful gums, subperiosteal hematomas, hemorrhages, bleeding into joints, hyperkeratotic papular rashes, impaired wound healing, weakened immune system

74
Q

Which drugs can induce serotonin syndrome when used with another serotonergic drug (e.g. MAO Inhibitors)?

A
  • Linezolid: binds to 50s and prevents formation of initiation complex
  • Odansetron
  • Tramadol
75
Q

How is diastolic heart failure characterized?

A
  • impaired myocardial relaxation and increased ventricular compliance
  • preserved EF
  • maintains EDV but increases End diastolic pressure
  • decompensation occurs when LVEDP increases enough to transmit backwards to cause pulmonary edema
  • there is an upward and slight left shift of the pressure volume curve
76
Q

Function of major basic protein from Eosiniophils?

A
  • to kill helminths

- may contribute to bronchial epithelial damage in atopic asthma

77
Q

Which gram + group can grow in hypertonic saline?

A

Enterococci

78
Q

What vitamin can be given for a child with measles to help with recovery?

A

Vitamin A-reduces time of recovery of diarrhea and pneumonia

79
Q

why do patients taking daily maintenance nitrates need a nitrate free period, common during the night?

A

to decrease development of tolerance

80
Q

What can be seen on kidney biopsy in Multiple myeloma patients?

A

large eosinophilic casts (but not cell casts) formed from bence jones proteins in the tubular lumen
-drug induced interstitial nephritis can cause pyuria with eosinophils, but not eosinophilic casts

81
Q

Mechanism of action of ethambutol?

A

-inhibits arabinosyl transferase. Prevents carbohydrate polymerization, and therefore mycobacterial cell wall synthesis

82
Q

How to prevent neonatal tetanus?

A

from poor cord care or unhygienic delivery
-can be prevented by vaccinating pregnant mother, who can pass IgG to fetus via passive immunity until infant can be vaccinated at 2 months

83
Q

Mechanism of kidney stone formation in crohn’s disease?

A

-malabsorption.Lipid binds Ca and is excreted. Free oxalate is absorbed.

84
Q

What enzyme converts pro-carcinogens into active carcinogens

A

P450 microsomal monooxygenase
-metabolizes steroids, alcohol, toxins, –makes them more soluble and easier to excrete but also converts pro carcinogens to active metabolites

85
Q

How does kidney disease lead to renal osteodystrophy?

A
  • high phosphate levels in serum because kidneys have decreased ability to excrete
  • phosphate binds Calcium. Decreased calcium levels cause increase in PTH.
  • also decreased kidney synthesis of activated Vit D

USMLE (4 decks)

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