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Review / Wrong Answers > 6/13 UWorld > Flashcards

6/13 UWorld Flashcards

1
Q

Describe the pathophysiology of aortic aneurysm in syphilis

A

Tertiary syphilis begins with vaso vasorum endarteritis and obliteration, resulting in inflammation, ischemia, and weakening of the adventitia

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2
Q

What are the compenents of crescents in rapidly progressive glomerulonephritis

A

Fibrin and macrophages

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3
Q

What is the equation for number needed to treat?

A

1/ARR

  • Absolute risk reduction (ARR)
    • Looking at how much a beneficial intervention (rather than a risk factor) will affect the risk of disease
      • Risk of those not receiving intervention minus risk of those receiving intervention
    • Equation:
      • ARR = [c/(c+d)] - [a/(a+b)]
      • THINK: ARR = NPV – PPV
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4
Q

What is the equation for relative risk

A
  • Probability of getting disease in exposed group vs. probability of getting disease in unexposed
    • Calculated from cohort studies
  • Equation:
    • RR = [a/(a+b)] / [c/(c+d)]
  • Remember that it is a ratio! Not subtraction
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5
Q

Equation for odds ratio

A
  • Odds that group with disease (case) was exposed to a risk factor vs. odds that group without disease (control) was exposed
    • Calculated from case-control studies
  • Equation:
    • OR = [(a/c) / (b/d)] = ad/bc
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6
Q

Equation for relative risk reduction

A
  • The proportion of risk reduction attributable to the intervention as compared to a control
  • Equation:
    • RRR = 1 – RR
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7
Q

Equation for attributable risk

A
  • Difference in risk among exposed and risk among unexposed
  • Equation:
    • [a/(a+b)] – [c/(c+d)]
  • Same as relative risk, but subtraction instead of division
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8
Q

What pathogens cause ring enhancing lesions in the brain

A

Toxoplasmosis

CNS lymphoma

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9
Q

Where are enhancers/silencers located in reference to the gene they are working on (upstream, downstream

A

Can be located upstream, downstream, close to, far from, or even within (in an intron) the gene they are regulating

Vs. promoters which must be upstream

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10
Q

What type of HSR is hyperacute (minutes) transplant rejection

A

Type II HSR

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11
Q

Reverse transcription polymerase chain reaction is used to detect levels of what in a sample?

A

mRNA

RT-PCR used the sample mRNA to produce complementary DNA that can be amplified by PCR

Because cDNA is complementary to mRNA, it contains exons and any untranslated regions

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12
Q

Describe gram to calorie ratios for:

  • Protein
  • Carbohydrates
  • Fat
  • Ethanol
A

Protein = 4 cal/g

Carbs = 4 cal/g

Fat = 9 cal/g

Ethanol = 7 cal/g

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13
Q

Does oxygenated blood from mother to fetus come from the umbilical artery or umbilical vein

A

Vein

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14
Q
A
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15
Q

What disease presents with diffuse ST segment elevation in all EKG leads

A

Pericarditis

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16
Q

Do first generation antipsychotics treat positive or negative sx of Schizoprenia

A

Positive

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17
Q
A
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18
Q

What is the mechanism behind increased risk of TB in silicosis

A

Impaired phagolysosome formation

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19
Q

Describe the presentation of neurofibromatosis type 1

A
  • Neurocutaneous disorder characterized by café-au-lait spots, cutaneous neurofibromas, optic gliomas, pheochromocytomas, Lisch nodules (pigmented iris hamartomas)
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20
Q

Describe presentation of neurofibromatosis type 2

A
  • Bilateral acoustic schwannomas, juvenile cataracts, meningiomas, and ependymomas
  • Presentation:
    • Hearing loss, tinnitus, balance problems, hyperpigmented skin lesions, cataracts
  • REMEMBER 2’s:
    • Chr 22
    • Bilateral hearing loss
    • NF Type 2
    • Cataracts
21
Q

Mode of transmission of Hepatitis A

A

Travel to endemic areas

Contaminated water supply

Shellfish

22
Q

Mode of transmission of Hepatitis C

A

Exposure to infected blood

Sexual (less likely than Hep B to be transmitted this way)

23
Q

What anti-arrhythmic drug prolongs the QT interval but is associated with lower risk of torsade de pointes than the other QT-prolonging agents

A

Amiodarone

Other QT prolonging agent = Class IA (Procainamide, Quinidine, Disopyramide)

24
Q

What is a classic XR finding in Bacillus anthracis

A

Mediastinal widening

25
Q

What is unique about the capsule of Bacillus anthracis

A

It contains a D-glutamate capsule (remember poly-D) instead of polysaccharide

26
Q

What is the mutation associated with Lynch syndrome

A

MSH2, MLH1 – DNA mismatch repair

Not associated with APC mutation - recall that Lynch syndrome is hereditary nonpolyposis colon cancer (HNPCC)

27
Q

Symptoms of Parkinson’s

A
  • TRAPS + mask-like facies
    • Tremor (resting)
    • Rigidity (cogwheel)
    • Akinesia (or bradykinesia)
    • Postural instability
    • Staggering gait
28
Q

What adverse effects are likely to persist after adding carbidopa to levodopa

A

Carbidopa decreases peripheral conversion and enhances central converson of L-DOPA to DA

Will have more central side effects - anxiety and agitation

29
Q

What are the peripheral side effects of levadopa that are decreased with Carbidopa

A
  • Nausea and vomiting due to chemoreceptor stimulation
    • à nauseated hostage
  • Cardiac arrhythmias
    • à arrhythmia rope tying up the female hostage
  • Orthostatic hypotension
    • à female hostage passed out
30
Q

Where is the SA node located

A

R atrium near the opening of the SVC

31
Q

Where is the AV node located

A

RA near the septal cusp of the tricuspid valve

32
Q

What disease is associated with anti-mitochondrial antibodies

A

Primary biliary cirrhosis

33
Q

What antibody is associated with polymyositis/dermatomyositis

A

Anti-jo-1

ANA

34
Q

Describe the role of Cyclin D in cell replication

A

o Cyclin D activates CDK4 (kinase complex)

o This kinase complex will phosphorylate Rb protein

o Phosphorylated Rb becomes unbound from transcription factor E2F, allowing cell to progress from G1 to S phase

35
Q

Describe function of RAS (as an oncogene or tumor suppressor) + associated cancers

A
  • Oncogene = is a signal transducer (GTP-binding protein)
    • Ras is associated with growth factor receptors in an inactive GDP-bound state
    • Receptor binding causes GDP to be replaced with GTP, activating Ras
    • Activated Ras sends growth signals to the nucleus
    • Ras inactivates itself by cleaving GTP to GDP via GTPase protein
    • Mutated Ras inhibits the activity of GTPase, thus producing a prolonged activated state of Ras
  • Most common oncogene abnormality
  • Associated with:
    • o Pancreatic adenocarcinoma
    • o Cholangiocarcinoma
36
Q

Name the oncogene and the tumor suppressor associated with breast cancer

A

Oncogene = HER2 (EGFR)

Tumor suppressor = BRCA1/2

37
Q

What cancer will be CA 19-9+

A

Pancreatic cancer

38
Q

What cancers will be CEA+

A
  • CEA – carcinoembryonic antigen
    • § Colon cancer
    • § Pancreatic cancer
39
Q

What cancers will be AFP+

A

§ Hepatocellular carcinoma

§ Hepatoblastoma

§ Yolk sac tumor

§ Mixed germ cell tumor

40
Q

What cancers will be b-hCG+

A

§ Hydatidiform mole

§ Choriocarcinoma

§ Testicular cancer

§ Mixed germ cell tumor

41
Q

What cancers will be S-100+

A
  • o S-100 – Neural crest marker
    • § Melanoma
    • § Schwannoma
42
Q

What cancers will be alkaline phosphatase+

A

§ Metastasis to bone

§ Biliary disease

§ Paget disease of the bone

43
Q

What tumors will have psammoma bodies

A

Papillary thyroid carcinoma

Serous papillary cystadenocarcinoma of the ovary

Mesothelioma

Meningioma

44
Q

What tumors secrete erythropoietin

A
  • Potentially Really High Hematocrit
    • Pheochromocytoma
    • Renal cell carcinoma
    • Hepatocellular carcinoma
    • Hemangioblastoma
45
Q

Describe the synthesis of the pyrimidine, thymidine

A
  • Glutamine + CO2 + ATP converted to carbamoyl phosphate via carbamoly phosphate synthetase II
  • Carbomoyl phosphate converted to orotic acid
  • Orotic acid converted to UMP via UMP synthase
  • UMP to UDP
  • UDP to dUDP via ribonucleotide reductase
  • dUDP to dUMP
  • dUMP methylated to dTMP via thymidilate synthase
    • THF is what provides the carbon needed for methylation (THF to DHF)
    • Thymidylate synthase catalyzes the transfer of methyl group
    • DHF gets converted back to THF via dihydrofolate reductase
    • THF is then re-methylated to continue the cycle
46
Q

MOA of Methotrexate

A
  • Folate analog that competitively and irreversibly binds to dihydrofolate reductase, preventing convserion of DHF into THF
  • Inhibition of DHF reductase leads to a build-up of DHF
  • This means you have no THF to create dTMP
    • Interferes with the synthesis of DNA, RNA, and other rapidly dividing cells
    • Rapidly dividing cells are the ones that are preferentially targeted
    • Most effective during S phase (when cells are undergoing synthesis of new DNA)
47
Q

How do you reverse the toxicity of methotrexate

A
  • Leucovorin (folinic acid – reduced form of folate)
      • lucky feline (cat statue)
  • Can be used to reverse the toxicity effects of MTX (“leucovorin rescue”)
  • Folinic acid does not require DHF reductase
48
Q

MOA of 5-Fluorouracil (5-FU)

A

5-FU is a cytotoxic pyrimidine analog

5-FU is metabolized by intracellular reaction to it’s active form FDuMP

FDUMP forms a complex with THF and inhibits thymidylate synthase (conversion of dUMP to dTMP using carbon from THF)

Inhibition of thymidylate synthase by 5-FU will lead to a build-up of dUMP

49
Q

MOA of hydroxyurea

A
  • Recall:
    • The precursor of all pyramidine nucelotides is UMP, which is then phosphorylated to UDP
    • Ribonucleotide reductase will convert UDP to dUDP
    • dUDP can then be de-phosphorylated into dUMP
  • Hydroxyurea works by inhibiting ribonucleotide reductase so that UDP cannot be converted to dUDP, thus blocking the de novo synthesis of thymidine

Review / Wrong Answers (140 decks)

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