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UWORLD facts > june 1 > Flashcards

june 1 Flashcards

1
Q

what are the 2 possible enzyme deficiencies that can cause phenylketonuria

A

most are due to phenylalanine hydroxylase deficiency but some are due to dihydropteridine reductase deficiency leading to a BH4 deficiency.

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2
Q

what substances accumulate in PKU and what are deficient

A

Phenylalanine accumulates while serotonin and other neurotransmitters (catecholamines) are deficient

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3
Q

what is the drug of choice for status epilepticus

A

IV benzodiazepine like lorazepam

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4
Q

what is the MOA of benzodiazepines

A

enhance the effects of the GABA by increasing the influx of chloride in response to GABA binding

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5
Q

how does lowering pCO2 affect the brain circulation

A

a drop in pCO2 causes vasconstriction and increases vascular resistance and reduces cerebral blood flow

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6
Q

what is vertebral subluxation

A

its vertebral malalignment, it can be caused by chronic rheumatoid arthritis due to laxity/destruction of the transverse ligaments or progressive erosion or fracture of the odontoid processes can cause spinal cord compression due to posterior displacement of the odontoid

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7
Q

which drug is an opiod partial agonist and can precipitate withdrawl in opioid tolerant patients

A

Buprenophine

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8
Q

what is conversion disorder

A

neurologic symptom incompatible with any known neurologic disease; often acute onset assoicated with stress

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9
Q

what are the ergot compound and nonergot compound dopamine agonist?

A 
eargot = bromocriptine
non-ergot = pramipexole and ropinirole
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10
Q

which neuropeptides are affected by narcolepsy, and where are they produced

A

hypocretin-1 (orexin-A) and hypocretin-2 (orexin-B) levels are reduced in the CSF

they are made in the lateral hypothalamus and function to provide wakefulness and inhibit REM sleep related phenomena

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11
Q

what are the developmental derivatitives from the first pharyngeal arch

A

trigeminal nerve, mandible, mazilla, zygoma, incus, malleus and muscles of mastication (masseter, temporalisis, and pterygoids)

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12
Q

what are the derivatives from the 2nd pharyngeal arch

A

facial nerve, stapes, styloid process, lesser horn of hyoid and muscles of facial expression

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13
Q

what is the gene and protein affected in NF2 and the main clinical feature

A

NF2 tumor suppressor gene that codes for the protein merlin on chromosome 22

associated with bilateral acoustic neuromas

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14
Q

what are the 3 common clinical findings in NF1

A

cafe au lait spots, multiple neurofibromas and lisch nodules

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15
Q

what are findings of ulnar nerve injury

A

weakness on wrist flexion/adduction, finger abduction/adduction and flexion of the 4th and 5th digits and loss of sensation in the ulnar distribution

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16
Q

which nerve exits through the obturator cannel

A

obturator nerve

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17
Q

what does the obturator nerve innervate

A

obturator externus muscle and the adductors of the thigh and a small area of sensation over the distal medial thigh

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18
Q

describe the corse of the median nerve in the forearm

A

it courses between the humeral and ulnar heads of the pronator teres muscle and then runs between the flexor digitorup superficialis and the flexor digitorum profundus muscles before crossing the wrist within the carpal tunnel

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19
Q

what does a proximal median nerve lesion cause

A

sensory loss over the first 3 digits and impairment of thumb flexion and opposition, flexion of the second and third digits and wrist flexion and abduction

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20
Q

what is the treatment for Wilson’s disease

A

D-penicillamine (chelation therapy to remove excess loosely bound serum copper)

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21
Q

what 3 findings are common with a fat embolism

A

acute onset neurologic abnormalities, hypoxemia, petechial rash

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22
Q

describe the pathogenesis of HIV associated dementia

A

HIV infected monocytes initally cross the BBB to become perivascular macrophages. Activated macrophages and microglial cells form groups (microglial nodules) around small areas of necrosis and may fuse to form multinucleated giant cells. Neuronal damage is from inflammatory cytokine release by macrophages/microglial cells and the direct toxic effects of HIV-derived protein

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23
Q

what are the clinical features of homocystinuria

A

hypercoagulability and thromboembolic occlusion, ectopic lentis and intellectual disability

cysteine becomes essential in their diet since it can no longer be formed from homocysteine and the buildup leads to increased methionine in the serum

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24
Q

how do you treat hereditary orotic aciduria

A

uridine supplementation allows for bypass of thedefective uridine 5’-monophosphate (UMP) synthase that convers orotic acid to UMP. Uridine can be converted to UMP via nucleoside kinases

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25
Q

what is the drug of choice for trigeminal neuralgia

A

carbamazepine

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26
Q

what 2 types of neoplasms can present as small blueish neoplasm occuring underneath a nail bed

A

glomus tumor (glomangioma or a subungual melanoma

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27
Q

what is a glomangioma

A

tumor of the modified smooth muscle cells of a glomus body. Glomus bodies control thermoregulatory functions by shunting blood away from the skin in cold temperatures and towards the skin surface in heat

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28
Q

what are 3 approaches to alzheimer’s therapy

A
  1. enhanced cholinergic neurotransmission
  2. Antioxidants - neuroprotection
  3. NMDA receptro antagonism
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29
Q

what nerve is likely to be injured due to sudden upward jerking for the arm at the shoulder?

A

the lower trunk of the brachial plexus (carries fibers from C8 and T1 which contribute to the median and ulnar nerves which together innervate all of the muscles of the hand causing a total claw hand deformity)

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30
Q

how does a tracheoesophageal fistula present

A

prenatal US may show polyhydraminos

after birth there is drooling, choking, coughing, and cyanosis with feeds

xray will show a atretic esophageal pouch and stomach bubble (air in the stomach)

31
Q

excessive matrix metalloproteinase activity and myofibroblast accumulation in wound margins indicates what process

A

contracture

32
Q

how is fatty acid B-oxidation inhibited when glucose is present

A

cytosolic acetyl-coA carboxylase converts acetyl-CoA to malonyl-CoA during the rate limiting step of fatty acid synthesis. Malonyl-CoA also inhibits the mitochondrial carnitine acyltransferase to inhibit beta-oxidation of newly formed fatty acids

33
Q

what 2 vitamins is breast milk typically deficient of?

A

vitamins D and K

iron levels are insufficient after 4 months of breast feeding

34
Q

what is Hartnup disease

A

a disease involving defective absorption of aromatic amino acids (most importantly tryptophan)

leads to a niacin deficiency (B3) (give supplemental niacin)

35
Q

what limits the effectivity of drugs that selectively dilate arterioles (like hydralazinen minoxidil) in the treatment of hypertension

A

baroreceptor stimulation leading to increased sympathetic activation which increases HR, contractility, CO, and the RAA system resulting in sodium and fluid retention

36
Q

what type of collagen is in scar tissue? and where else is this type of collagen found

A

type I

dermis, bone, tendons, ligaments, dentin, cornea, blood vessels

this is the type that is defective in OI

37
Q

where is type II collagen mainly found

A

cartilage

38
Q

where is type III collagen mainly found

A

skin, lungs, intestines, blood vessels, bone marrow, lymphatics, granulation tissue

39
Q

where is type IV collagen mainly found

A

basement membranes (defective in Alport syndrome)

40
Q

occlusion of which artery would cause ischemia in the inferior surface of the heart

A

the posterior descending artery which is a branch of the right coronary artery in most people (rt dominant circulation)

41
Q

repeat spontaneous lobar hemorrhages are most commonly due to what

A

cerebral amyloid angiopathy (especially in pts > 60 y/o and most commonly affects the occipital and parietal lobe causing vision and sensory changes)

42
Q

The deep inguinal ring is an opening in what structure

A

the transversalis fascia

43
Q

the superficial inguinal ring is an opening in what structure

A

the external oblique muscle aponeurosis

44
Q

what is the cause of insulin resistance during pregnancy

A

human placental lactogen (chorionic somatomammotropin) causes increased insulin resistance to provide increased glucose to the fetus despite stimulating pancreatic beta cells to increase insulin production. maternal lipolysis and proteolysis are also increased by hPL.

45
Q

what cell type produces mullerian inhibiting factor

A

sertoli cells (absents of Sertoli cells leads to both female and male internal genitalia being present but male external genitalia)

46
Q

what labratory findings are seen in Klinefelter syndrome

A

decreased testosterone and increased LH, FSH and estradiol

47
Q

what are the histological findings of cardiac biopsy in acute rheumatic fever

A 
Aschoff bodies (interstitial myocardial granuloma)
Anitschkow cells (caterpillar cells, plump macrophages with slender chromatin ribbons) 
interstial fibrosis with central lymphocytes and macrophages
48
Q

elevated arginine levels in blood and CSF are indicative of what enzyme disorder? what metabolic process is affected?

A

arginase deficiency
arginase normally converts arginine to urea and ornithine as a part of the urea cycle. (unlike other urea cycle disorders there is no hyperammonemia)

tx with a low protein diet without arginine

49
Q

which cytokine is involved in keloid formation

A

excessive TGF-B (should normally decrease in the maturation phase of wound healing)

50
Q

what is ciprofloxacin’s MOA

A

inhibits bacterial DNA gyrase aka Topoisomerase II

51
Q

what is appropriate contact precautions for organisms like C. diff and MRSA or VRE

A 
Gloves and gown 
hand hygiene (soap and water for c. diff)
52
Q

what structures are at risk of being injured with a mid-humerous arm break

A 
radial nerve (wrist drop)
deep brachial artery (profunda brachii)
53
Q

what 2 enzymes are elevated in the amniotic fluid indicating a neural tube defect

A

AFP (amniotic fluid and maternal serum) and acetylcholinesterase (amniotic fluid only)

54
Q

what bone findings are seen with hyperparathyroidism

A

subperiosteal thinning/ erosions of that hand, a granular “salt and pepper” skull and osteolytic cysts in the long bones (osteitis fibrosa cystica) brown tumor bone cysts

55
Q

what is phentolamine mesylates MOA

A

its an alpha receptor blocker - causes vasodilation (counteracts NE)

56
Q

what medications can worsen HOCM

A

vasodilators and diuretics due to decreased left ventricular volume and decreased systemic vascular resistance

57
Q

what are the symptoms of vitamin E deficency

A

neuromuscular disease (myopathy, ataxia, polyneuropathy) and hemolytic anemia

58
Q

describe the disease course of Alkaptonuria

A

relatively benign in childhood but leads to deposition of blue-black material in connective tissue (scerae and ear,) Deposits in the joint space leads to ankylosis, motion restriction and significant pain. Urine will turn black when left out

due to a deficiency in homogentisic acid dioxygenase

59
Q

what lab results may be seen in eosinophilic granulmonatosis with polyangiitis (Churg-Strauss)

A

peripheral eosinophilia

Antibody to neutrophil myeloperoxidase (p-ANCA)

60
Q

which muscles attach to the lateral epicondyl

A

extensor carpi radialis brevis and extensor digitorum - wrist extenders

injury = tenis elbow

61
Q

where do wrist flexors attach

A

medial epicondyl

injury = golf elbow

62
Q

what is an important mediator of giant cell arterititis

A

IL-6 and cytokine production

63
Q

what is the MOA of the toxin produced by C. perfringens

A

lecithinase aka alpha toxin aka phospholipase C catalyzes the splitting of phospholipid molecules, by hydrolysis of lecithin containing lipoprotein complexes in cell membranes

64
Q

what are the 2 main flexors of the hip

A

psoas major and iliacus

65
Q

what are signs of a psoas abcess

A

fever, back or flank pain, inguinal mass, and difficulty walking, pain when the hip is extended

66
Q

what disease presents with transmural inflammation of the arterial wall with fibrinoid necrosis predominantly involving small and medium vessels (sparing the lung)

A

polyarteritis nodosa

67
Q

where is osteonecrosis most likely to occur and what artery is involved

A

femoral head and neck due to insufficiency of the medial femoral circumflex artery (can occur due to a displaced femoral neck fracture)

68
Q

what are of the bone is most commonly affected by hematogenous osteomyelitis

A

metaphysis of long bones due to the slower blood flow and capillary fenestrae. it usually affects children

69
Q

humerus fracture with anterolateral displacement is most likely to injure which structure? Anteriomedial displacement?

A

anterolateral may injury the radial nerve

anteromedial may injure the medial nerve and/or brachial artery injury

70
Q

pain and tenderness in the anatomical snuffbox after falling on an outstretched hand indicates? and what are possible complications?

A

a scaphoid fracture (most common of the carpal bone fractures)

complications include avascular necrosis and nonunion

71
Q

what is a first line treatment for major depressive disorder that does not cause sexual dysfunction

A

Bupropion ( NE and D reuptake inhibitor)

72
Q

how does the MDR1 gene cause resistance to chemotherapy drugs

A

the human multidrug resistance gene (MDR1) codes for P-glycoprotein a transmembrane ATP-dependent efflux pump protein that has a broad specificity for hydrophobic compounds. It reduces the influx of drugs and increases the efflux

73
Q

how is GnRH, LH, FSH, and estrogen affected in an anorexic patient

A

GnRH is decreased leaded to decreases of all the others

UWORLD facts (7 decks)

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