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USMLE Step 1: Part 1 COPY > USMLE Rx: Week of 10/10/16 > Flashcards

USMLE Rx: Week of 10/10/16 Flashcards

1
Q

What is the best way to differentiate between HSV and VZV?

A

HSV is less confined to dermatomes and immunosuppression is not necessary for reactivation.

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2
Q

True or false: the C1 dermatome covers the top of the head.

A

False. The head sensation goes from V1 (trigeminal) covering the forehead to C2 covering the scalp and back of the head.

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3
Q

The C3 dermatome covers _______________.

A

the “high turtleneck” area of the body –just like C3PO’s weird golden neck thing

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4
Q

The main location where CSF joins the venous blood is the ________________.

A

superior sagittal sinus

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5
Q

What disorder presents in the elderly with dementia, incontinence, and wobbly gait?

A

Normal pressure hydrocephalus–a condition in which the ventricles are enlarged, but there is no increase LP pressure. It often is caused by a communicating hydrocephalus, meaning the superior sagittal sinus is occluded.

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6
Q

Recall that cerebellar lesions produce __________ tremors.

A

intention (that is, not resting)

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7
Q

Treat Wilson’s disease with _______________.

A

penicillamine (think of stabbing Wilson the volleyball with A MEAN PENCIL)

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8
Q

First-line treatment for Lyme disease is _____________.

A

doxycycline (think of LiME pie messing up your teeth, just like doxycycline stains kids’ teeth)

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9
Q

Supportive treatment is recommended for __________ viral meningitis, while acyclovir is recommended for _________ viral meningitis.

A

RNA (most cases); DNA (herpes, Epstein-Barr, VZV)

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10
Q

Describe the role of bleeding time.

A

It solely measures bleeding time, so those with hemophilia will have normal bleeding times.

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11
Q

____________ is used to treat subacute endocarditis, while ____________ is used to treat acute endocarditis.

A

Penicillin (being that the most common organisms are Streptococcus viridans and Staphylococcus epidermis); vancomycin

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12
Q

What are the four main nerves that control hip function?

A

Femoral: innervates vastus muscles; flexion
Obturator: innervates adductors; adduction
Sciatic: innervates hamstrings; extension
Inferior gluteal: innervates glutes; extension and lateral rotation

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13
Q

The only muscle that arises from the third branchial arch does what?

A

Elevates the pharynx (this is the stylopharyngeus, innervated by the glossopharyngeal nerve)

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14
Q

What is the usefulness of the cocaine and hydroxyamphetamine eye drop test (in Horner syndrome)?

A

It tells you where –pre- or post-ganglionic –the disruption in the sympathetic chain is. If neither drop elicits dilation, then the lesion is post-ganglionic. If the hydroxyamphetamine drop (which induces healthy neurons to release norepinephrine) dilates the pupil, then it means the lesion is preganglionic.

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15
Q

True or false: you should CT a child who’s had a febrile seizure.

A

False. CTs are not indicated for febrile seizures. Instead, search for a source of the infection.

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16
Q

Differentiate factitious disorder and somatic symptom disorder.

A

In factitious disorder, the patient knows they are faking. While in somatic symptom disorder, the patient presents with a range of different symptoms without clear causes, but they are not consciously faking.

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17
Q

In addition to the T cell binding MHC II using CD4, what signal interaction is needed to activate T cells?

A

T-cell CD28 binding APC CD80 (also called B7)

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18
Q

Describe alkaptonuria.

A

An autosomal recessive disorder in which people lack the enzyme homogentistic acid oxidase. As a result, the molecule homogentistic acid builds up. It makes the urine black and accumulates in the bones, ears, and sclera –leading to arthritis and hyperpigmentation, respectively

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19
Q

An infant presents with poor growth and nonpolar amino acids in his urine. What enzyme is he lacking?

A

This is maple-syrup urine disease, and autosomal recessive disorder in which alpha-ketoacid dehydrogenase is defective. As a result, leucine, isoleucine, and valine appear in the urine instead of being recycled. Additionally, gluconeogenesis is impaired by an unknown mechanism –leading to hypoglycemia. Hypotonia also occurs. Death results if untreated (treated with diets low in those three amino acids and thiamine).

“I Love Vermont maple syrup from B1anches.”
Isoleucine, Leucine, Valine… supplement with thiamine.

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20
Q

Modification of the ribosomal binding site is a common method of resistance to ________________.

A

tetracyclines, macrolides, and chloramphenicol

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21
Q

Acetylation is a common method of resistance to _______________.

A

aminoglycosides

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22
Q

Efflux pumps are commonly used by bacteria to develop resistance to _____________.

A

tetracyclines

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23
Q

Overtreatment for which vitamin deficiency can lead to flushing?

A

Niacin (B3)

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24
Q

In addition to the three Ds, what else can niacin deficiency cause?

A

Dementia
Dermatitis
Diarrhea
Glossitis

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25
Q

AIDS patients can have sudden loss of spinal reflexes due to what infection?

A

CMV (treat with ganciclovir)

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26
Q

In addition to being necessary for proline and lysine hydroxylation, vitamin C is also necessary for _______________.

A

iron absorption

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27
Q

Folic acid has another, non-DNA role. What is it?

A

Participation in one-carbon transfer reactions that synthesize norepinephrine from dopamine

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28
Q

What neurocutaneous disorder presents with immunoglobulin abnormalities?

A

Ataxia-telangiectasia (because of difficulty switching classes)

29
Q

Insulin acts on what type of receptor?

A

Tyrosine kinase

30
Q

High C-peptide serum indicates?

A

That the insulin is endogenous (as opposed to injected)

31
Q

What is the mechanism of loss in Lesch-Nyhan?

A

Hypoxanthine guanine phosphoribosyltransferase is a purine salvage enzyme. Loss of it (due to x-linked defect) leads to accumulation of uric acid because purine precursors are not being recycled back into the pathway.

32
Q

Amantadine has what side effects?

A

Ataxia and slurred speech (think of a drunk manatee crashing into stuff)

33
Q

True or false: factor V Leiden homozygosity is universally fatal.

A

False. People who are heterozygous for factor V Leiden have DVTs in unusual places and later in age, while those who are homozygous have it earlier –like in young adulthood – but it is not fatal.

34
Q

What sensory deficit is likely to accompany absence of the biceps reflex?

A

Sensation in the lateral forearm, because the musculocutaneous nerve innervates the biceps and the lateral forearm

35
Q

What drug is always given with imipenem?

A

Cilastatin

It is an inhibitor of dehydropeptidase-1,the enzyme in the PCT that metabolizes imipenem. Giving this maintains serum levels of imipenem.

Notably, meropenem, another carbapenem, is resistant to degradation by dehydropeptidase-1.

36
Q

What tests can PCR be used for?

A

Identifying genes of interest –it amplifies segments of DNA based on a provided primer complementary to your gene of interest.

37
Q

True or false: Southern blots can be used to determine paternity.

A

True! It is based on DNA-DNA hybridization, and thus can pick up matching between mother and father.

38
Q

Remember that in palindromic DNA sequences, it is palindromic _______________ strands.

A

across strands, meaning this sequence is palindromic:

TGTACA

while this is not:

TGAAGT

39
Q

True or false: boys with Bruton’s will have some Ig.

A

True! All levels will be low, but there will be some Ig.

40
Q

A woman presents three weeks after an MI with chest pain and a pericardial rub. How should you treat her?

A

Give corticosteroids, aspirin, and NSAIDs

This is Dressler syndrome –autoimmune fibrinous pericarditis after an MI.

41
Q

True or false: hyper-IgM syndrome results from a defect in a B cell receptor.

A

False! It is a defect on T cells (CD40) that helps class switching.

42
Q

Why would you hyperventilate someone with papilledema?

A

CO2 is a potent vasodilator, so decreasing the CO2 in someone with increased ICP – indicated by papilledema – can help lessen the damage of intracranial hypertension.

43
Q

What is the formula for clearance?

A

(0.7 x Vd) / (T[1/2])

44
Q

How can you calculate volume of distribution for an orally administered drug?

A

(Cp x Vd) / F = amount of drug given

Where F is the bioavailability factor (1 for IV drugs).

45
Q

There are two enzymes in which defects lead to phenylketonuria. What are they?

A

Phenylalanine hydroxylase and tetrahydrobiopterin

46
Q

How do you calculate odds ratio?

A

(exposed cases with disease x controls not exposed) / (cases without exposure x control cases exposed)

diagonal multiplication

47
Q

Polydactyly and cleft lip are characteristic of which trisomy?

A

Patau (Patau = Polydactyly = Palate abnormalities)

48
Q

What organism causes malaria?

A

Plasmodium falciparum

49
Q

If a question tells you that a disc slipped between L5 and S1, what nerve root is going to be occluded?

A

S1 (point being that the nerve beneath the disc will be blocked)

50
Q

What nerve roots make up the femoral nerve?

A

L2 - L4

51
Q

What mnemonic helps you remember the foramina through which the branches of the trigeminal nerve exit the skull?

A

Standing Room Only

Superior orbital fissure (ophthalmic)
foramen Rotundum (maxillary) 
foramen Ovale (mandibular)
52
Q

True or false: the internal carotid artery enters the skull through the foramen spinosum.

A

False. The middle meningeal artery enters the skull through the foramen spinosum.

53
Q

The foramen through which the internal jugular vein passes also transmits what nerves?

A

The jugular foramen allows the passage of CN IX, X, and XI

54
Q

The facial nerve exits through the ___________ foramen.

A

stylomastoid

55
Q

What is the formula for positive predictive value?

A

TP / (TP + FP)

56
Q

Case-control studies can only tell you _________. If you want to know risk, you need to do a ____________ study.

A

odds ratio; prospective cohort

57
Q

Those with coarctation of the aorta have an increased risk of which two cardiovascular disorders?

A

Cerebral hemorrhage and bacterial endocarditis

58
Q

Th1 cells secrete interferon-gamma. What does that cytokine do to macrophages?

A

It stimulates the macrophages to up-regulate antigen presentation and to increase lysosomal proliferation.

(Think of the Th1 cell saying: “GAMe’s UP –I’m INTERFERing.”)

59
Q

What cell secretes IL-12 and what does it do?

A

IL-12 is secreted by macrophages and stimulates Th0 to become Th1.

(Think of a jury (of twelve) delivering 1 verdict!)

60
Q

Once again review the cranial nerves by branchial arch?

A 
1 = V
2 = VII
3 = IX
4/6 = X
61
Q

What ribonucleotides participate in splicing reactions?

A

‘5 GU …… AG

Get yoU… A-Goin’

62
Q

A jaundiced infant presents with hypotonia. Low levels of what serum test might indicate worse prognosis?

A

Albumin, because albumin binds to bilirubin and prevents it from entering the brain

63
Q

What gel can N. gonorrhoeae grow on?

A

Thayer-Martin

64
Q

Southern blots must have ___________. Considering this, what is gel electrophoresis?

A

labeled probes; a process in which ultraviolet light is used to view bands

65
Q

Otitis externa is most often caused by _____________.

A

Pseudomonas aeruginosa (P. EARuginosa)

66
Q

What’s a good way to distinguish between Pseudomonas and Escherichia?

A

Pseudomonas cannot ferment lactose, while Escherichia can.

67
Q

Describe the types of rejection and the times they present.

A

Hyperacute: requires pre-existing antibodies; complement mediated; induces immediate necrosis (within minutes)

Acute: CD8 and antibodies develop after implantation (weeks to months)

Chronic: CD4-mediated, in which they respond to APCs presenting foreign organ peptides (months to years)

68
Q

Discolored teeth are a sign of ___________.

A

osteogenesis imperfecta

69
Q

Progressive hearing loss is a potential complication of what autosomal-dominant connective tissue disorder?

A

Osteogenesis imperfecta (because the ossicles get damaged)

USMLE Step 1: Part 1 COPY (243 decks)

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