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1 USMLE-rx > March 28 > Flashcards

March 28 Flashcards

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USMLE® Step 1 flashcards
1
Q

What is the karyotype of a complete hydatidiform mole and what are its components?

A

46, XX or 46, XY

Completely consisting of paternal DNA–Results when 2 sperm fertilize an empty egg
–No fetal parts

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2
Q

What enzyme is deficient in McArdle disease (type V Glycogen storage disease), which presents with painful muscle cramps and myoglobinuria?

A

Skeletal muscle glycogen phosphorylase–Myophosphorylase

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3
Q

What enzyme is a rate-determining enzyme in renal gluconeogenesis?

A

Fructose-1,6-bisphosphatase

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4
Q

What is involved in smooth muscle contraction that is not in skeletal muscle contraction?

A

Phosphorylation of myosin occurs with smooth muscle

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5
Q

Small cell lung carcinoma is associated with what paraneoplastic syndromes?

A

ACTH–Cushing syndrome
SIADH
Lambert-Eaton myasthenic syndrome–Antibodies against presynaptic Ca channels

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6
Q

What is the cause of the cardiotoxicity seen with Doxorubicin?

A

Generation of free radicals

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7
Q

What genetic abnormality is associated with sickle cell anemia?

A

Substitution of valine for glutamic acid in 6th position of B-globin chain

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8
Q

What malignant ovarian neoplasm is indicated by postmenopausal bleeding in women in 50s and what is shown histologically?

A

Granulosa cell tumor–estrogen producing tumor

Histo–Call-Exner bodies–granulosa cells arranged haphazardly around collections of eosinophilic fluid
–resemble primordial follicles

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9
Q

What chromosomes are BRCA1/BRCA2 genes found?

A

17 and 13 respectively

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10
Q

What disease is characterized by eczematous lesions of nipple/areola with large halo-like cells on histo and what underlying malignancy is almost always present?

A

Paget disease of breast–with underlying ductal carcinoma

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11
Q

Gram-positive cocci with no hemolysis on sheeps blood agar?

A

Enterococcus

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12
Q

Isolated cleft palate presents with problems with breastfeeding and choking and coughing. What is the cause of this isolated abnormality?

A

Failure of palatine processes to fuse

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13
Q

The 5 examples of passive immunization after exposure?

A 
Tetanus toxin
Botulinum toxin
HBV
Varicella
Rabies

To Be Healed Very Rapidly

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14
Q

Damage to what nerve impairs pts ability to stand from sitting position, prevents pt from ascending stairs or being able to jump and what is the most common cause of this in elderly pts?

A

Inferior gluteal nerve–which innervates the gluteus maximus

Posterior hip dislocation

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15
Q

What is seen on microscopy of pt with Crohn disease?

A

Noncaseating granulomas and lymphoid aggregates

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16
Q

What disc level is involved when pt presents with weakness of plantar flexion, difficulty in toe-walking, and decreased Achilles reflex?

A

L5-S1

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17
Q

What disc level is involved when pt presents with weakness of dorsiflexion, difficulty in heel-walking?

A

L4-L5

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18
Q

What disc level is involved when pt presents with weakness of knee extension and decreased patellar reflex?

A

L3-L4

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19
Q

What does a lower Km and Vmax indicate?

A

Lower Km–increased affinity

Lower Vmax–lower capacity

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20
Q

What enzyme is deficient in Fabry disease which presents with triad of episodic peripheral neuropathy, angiokeratomas and hypohidrosis and leads to renal failure and CVD? What substrate accumulates?

A

a-galactosidase A is deficient

Ceramide trihexoside accumulates

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21
Q

What causes rise in temperature shortly after ovulation?

A

Progesterone released from the corpus luteum

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22
Q

What does the Achilles reflex test?

A

S1-S2

23
Q

How does prolactin prevent ovulation?

A

By inhibiting the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus
–leads to decreases in LH and FSH from the anterior pituitary

24
Q

What disease presents with cola-colored urine in the morning due to increased hemosiderin in the urine and what is the cause of this disease?

A

Paroxysmal nocturnal hemoglobinuria–caused by increased complement-mediated intravascular RBC lysis–mutation in PIG-A GPI anchor

25
Q

What protein is involved in axonal transport of vesicles?

A

Tubulin (a+B) –dynein (+–> -) and kinesin (- –> +)

26
Q

What is cytokeratin a marker for?

A

Expressed by cells of epithelial origin and is used for screening of adenocarcinoma of the GI/GU

27
Q

Alcoholic presents with hypoglycemia–what is causing this?

A

Increased NADH:NAD+ ratio by ETOH metabolism –diverting pyruvate to lactate and oxaloacetate to malate which inhibits gluconeogenesis by the liver–causing hypoglycemia

28
Q

What disease is caused by failure of DNA repair of thymidine dimers and increases photosensitivity of the skin?

A

Xeroderma pigmentosum

29
Q

Nitroprusside toxicity causes a build up to ______ causing inhibition of _______.

A

Cyanide

Mitochondrial cytochrome oxidase in the ETC

30
Q

Pts with HLA-DR5 are at an increased risk of developing what 2 autoimmune diseases?

A

Hashimoto thyroiditis

Pernicious anemia

31
Q

What is the tx for narcolepsy?

A

Amphetamines/modafinil-daytime stimulants

Sodium oxybate–for nighttime

32
Q

What is the most important prognostic factor in a pt with tetrology of fallot?

A

Degree of pulmonary stenosis

33
Q

What is seen on EM of pt with acute poststrep GN?

A

Subepithelial immune complex (IC) humps

34
Q

What disease produces a hyper coagulable state that can lead to DVT/PE?

A

Factor V Leiden –production of mutant factor V that is resistant to degradation by activated protein C

Can also lead to cerebral vein thromboses and recurrent pregnancy loss

35
Q

E. coli can uses glucose for metabolism, but when glucose is low and lactose is present what occurs in order for E. coli to used lactose instead of glucose?

A

Lactose stimulates the lac operon and allolactose acts as a inducer by binding to and inactivating the repressor

Since the repressor is inactive–increased cAMP can bind the lac operon and allow for lactose metabolism

36
Q

What 2 clotting factors are inactivated by proteins C and S?

A

Va and VIIIa

37
Q

Rheumatic heart disease causes what cardiac abnormality and what type of murmur is heard?

A

Mitral stenosis – delayed rumbling late diastolic murmur heard best at apex

38
Q

Drainage of liver into systemic circulation occurs through the ______.

A

Hepatic vein then into IVC

Portal vein drains GI into liver

39
Q

What enzyme is affected with lead poisoning?

A

aminolevulinic acid dehydratase –its inhibited leading to accusation of protoporphyrin and d-ALA

40
Q

What is deficient in thrombotic thrombocytopenic purpura, which presents with pentad of neurologic and renal symptoms, fever, thrombocytopenia, and microangiopathic hemolytic anemia?

A

vWF metalloprotease

41
Q

What 2 Vasculitides are associated with increased ESR?

A

Large-vessel vasculitis

  • Giant cell (temporal) arteritis
  • Takayasu arteritis
42
Q

What is the antidote for benzo toxicity and what is its MOA?

A

Flumazenil—competitive inhibitor at GABA-A benzo receptor

43
Q

What does a selective COX-2 inhibitor (Celecoxib) selectively inhibit?

A

Prostacyclin–PGI2–decreases platelet aggregation

44
Q

What do pt with SLE often have a false positive for?

A

False positive VDRL

45
Q

Pemphigus vulgaris involves ______ antibodies against _____.

A

IgG–desmoglein (component of desmosomes also called macula adherens

46
Q

How is kidney clearance calculated?

A

UV/P

47
Q

What lab values are seen with secondary hyperparathyroidism caused by renal disease?

A

Decreased Ca
Increased PO4
Increased ALP
Increased PTH

48
Q

Increased intracranial pressure in a newborn post group B strep infection meningitis that has healed is most likely caused by?

A

Communicating hydrocephalus–decreased absorption of CSF by the arachnoid villi caused by scarring from the infection

49
Q

What does an increased temperature during exercise do to the O2 dissociation curve?

A

Shifts it to the right causing decreased affinity of Hb for O2 allowing for increased unloading of O2 to muscle

50
Q

I-cell disease results in coarse facial features, clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes. What is defected in this disorder?

A

Inherited lysosomal storage disorder–with defect in N-acetylglucosaminyl-1-phosphotransferase—resulting in failure of golgi to phosphorylate mannose residues at cis golgi

Inclusion bodies are seen in cytoplasm of cells

51
Q

When are fetuses extremely susceptible to teratogens?

A

3-8wks

52
Q

Long term antipsychotic use can result in _____ caused by antagonism of ____ pathway?

A

EPS symptoms –caused by antagonism of D2-dopamine receptors

53
Q

What cell type does EBV attack and through what receptor?

A

B cells–through CD 21 receptor

B cells express CD 19, 20, and 21

54
Q

What part of the lymph node enlarges when there is an extreme cellular immune response, such as with a viral infection?

A

Paracortex

1 USMLE-rx (16 decks)

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