usmle2: block4 Flashcards
HIV protease inhibitors
specifically cleave gag (p24) and pol (enzymes) gene products into functional pieces
VHL
- hemangioblastoma
- cerebellum & retinal - renal cell carcinoma
- pheochromocytoma
also cysts in kidney and pancreas
how does CO cause hypoxia
- binds to heme w/ higher affinity than O2
- shifts hemoglobin dissociation curve all the way to left (no longer sigmoidal)
- - doesn’t release o2 anymore - impairs ETC
why does HbF have greater affinity for oxygen than HgA?
bc HbF doesn’t bind to 2,3BPG
where does Cu2+ in wilson’s disease deposit in eye (Kayser-Fleischer ring)
cornea: descement’s membrane
how does wilson’s disease present
30-40s,
hepatitis, splenomegaly, hemolytic anemia
basal gangia (lentiform nuc) damage: dystonia, tremor, dysarthria
kayser-fleisher ring
what is the main enzyme responsible for oxidative damage by neutrophils
NADPH oxidase, unique
converts O2 into superoxide
main task!
superoxide dismutase acts as either 1. scavenger for these free radicals, in all cells
2. or helps made H202, and w/ MPO, making bleach for further attacking
where is NADPH oxidase located
membrane protein of phagosome
aldehyde dehydrogenase
converts aldehyde into carboxylic acid
impt for alcohol metabolism.
blocked by disulfram
how does sclerosing adenosis present
usu as a density on mammogram / incidentally on biopsy
usu not a mass
most common causes of palpable nodular masses in breast
fibrocystic changes
usu poorly defined, diffuse increase in consistency throughout breast tissue
often multiple and painful, w. tenderness during premenstrual phase of cycle
presentation of mammary duct ectasia
ill-defined, palpable periareolar mass
may be confused w/ carcinoma
can have skin retraction and thick creamy or bloody nipple discharge
dermoepidermal junction aggregates of large cells that fuse w/ adjacent nests
atypical cells w/ irregular nuclear contours, hyperchromasia, round/spindle shaped
dysplastic nevus, which can evolve into melanoma
recall: nevus can be junctional, compound, or intradermal. malignant melanoma w/ pleomorphism
squamous cell carcinoma on histology
will have keratin pearls
basal cell carcinoma on histology
basaloid tumors either
- budding from epidermis or
- residing within the dermis w/ nuclear palisading & retraction artifact evident along periphery of cell nests
dysplastic nevus syndrome
chr 9p21
‘familial melanoma’
dermatofibrosarcoma protuberans
fibroblasts in a cartwheel/storiform patteerm
&
supernumerary ring chromosomes
langerhans cell histiocytosis
prolfierative disorders of dendritic langerhans cells from monocytic lineage
presentation:
lytic bone lesion & skin rash in child
or
recurrent otitis media with a mass involving mastoid bone
cells = functionally immature, do not efficienctly stimulate primart T lymphocytes via antigen presentation
express S-100 (mesodermal origin)
Bierbeck granules = TENIS racket on eM
Bierbeck tennis racket granules on EM
langerhans cell histiocytosis
flumazenil
bind to & blocks GABAb at the benzodiazepine binding spot
exercise on LV: HR LV end-systolic vol LV end-diastolic vol LV end-diastolic pressure
- HR increases (less parasymph, more sympth
- LV end systolic decreases (more preload, less afterload
- LV end diastolic vol increases
LV end-diastolic pressure does not change
–> decrease in TPR counterbalanced by increased cardiac output
clinical signs of alcoholic cerebellar degeneration
degenerate cerebellar vermis and anterior cerebellar lobes
wide-based gait, truncal instability, ataxia, nystagmus, dysarthria
3 important DNA binding protein domains?
- leucine zippers (alpha helix)
- helix-loop-helix
- zinc finger motifs
leishmania transmission & histology
macrophage w/ amastigotes.
sandfly
kala-azar: spinking fever, hepatosplenomegaly, pancytopenia
starting products for pyrimidine synthesis
CO2 + glutamine + 2ATP
via carbamoyl phosphate synthetase II
where does purine / pyrimidine metabolism occur?
cytosol
peroxisomes play a role in… (3)
- lipid metabolism (beta oxidation)
- oxidative reactions
- purine catabolism
positive psoas sign suggests.. (2)
- psoas abscess
- appendicitis
quadratus lumborum
runs from 12th rib to iliac crest.
helps extend & laterally flex vertebral column
fixes 12th rib during inspiration
alcoholic cardiomyopathy
dilated cardiomyopathy
causes of dilated cardiomyopathy
i’m mad my pump failed
iatrogenic medications (doxorubicin, danorubicin) alcohol drugs (cocaine) myocarditis pregnancy familial
causes of restrictive cardiomyopathy
my pounding ‘art seems held still
metastasis pompe amyloidosis sarcoidosis hemochromatosis systemic sclerosis
cardio: eccentric hypertrophy vs. concentric
eccentric: added in series: dilated cardiomyopathy
concentric: added in parallel: hypertrophy
carbolfuschin staining
acid-fast staining
retained by mycolic acid
presentation of choriocarcinoma
trophoblasts with NO VILLI
weeks following..
- normal birth
- evacuation of mole
- following an abortion
can present w/ metastasis to lungs, vagina, brain, liver, or kidney at time of diagnosis
placenta accreta results from
abscence of decidual layer
placenta stuck to uterine myomatrium
immediate postpartum bleeding secondary to failed placental separation
benzoyl peroxide
oxidizes bacterial proteins
bacteriostatic against propionibacterium acnes
chlorhexadine
antiseptic used as skin / dental cleanser
acitretin, tretinoin,adapalene, tazarotene
retinoid medications, bind nuclear receptors
major risk factors for ischemic heart disease. greatest?
smoking HTN diabetes dyslipidemia history of coronary heart disease
greatest: smoking
how does smoking risk of ischemic heart disease (2)
- promotes atherosclerosis
- promotes platelet aggregation
have 2-3x risk of nonsmokers
alcohol on MI
2 standard servings per day, decreases risk of MI
excessive –> other heart problems: HTN, cardiomyopathy, MI
how does the vagus n. enter abdomen
w/ esophagus (T10)
how does the thoracic duct enter abdomen
w/ aorta, T12
via aortic hiatus (median arcuate ligament of diaphragm)
how does the IVC enter abdomen
T8, central tendon of diaphragm
why are nitrates first line for angina pectoris
decrease both preload and afterload
arterial / venous vasodilation
type 2 maturity onset diabetes of young (MODY)
mutation in glucokinase (liver & beta pancreatic cells)
even higher Km that it should, higher threshold
von gierke mutation
glucose 6-phosphatase
only in live (glycogenolysis and gluconeogenesis)
have hepatomegaly and renomegaly
fructose / lactose in von gierke
bad. can’t be converted to glucose bc defect in gluconeogenesis.
deficiency in pompe
alpha 1,4 glucosidase
acid maltase
acid alpha glucosidase
prognosis of pompe
early clinical findings in heart
PAS+ granules in lysosomes
hypotonia, macroglossia, hypertrophic cardiomyopathy, VERY EARLY DEATH
pontine hemorrhage
often w/ HTN
pinpoint pupils, loss of horizontal gaze, quadriparesis, decerebrate posturing, rapidly evolving coma –> death
vasogenic edema
often via intracerebral neoplasm
disruption of blood brain barrier –> increased vascular permeability & plasma filtration into cerebral interstitium
vasogenic: fingers: white matter
cytotoxic edema
increased intracellular fluid WITHIN neurons, glial, endothelial cells. due to impaired Na+ / K+ pump
usu after ischemic insult
cytotoxic: white & grey matter
what type of cerebral causes an increased ICP: cytotoxic / vasogenic
VASOGENIC –> net gain of fluid in intracranial space
cytotoxic is a shift of fluid from extra/intracellular
how does an intracerebral neoplasm increase ICP?
vasogenic edema!
disrupts BBB
reiter’s syndrome classic & extra symptoms
classic: arthritis, urethritis, conjunctivitis
also: cutaneous findings; keratoderma blenorrhagica & balanitis circinata)
HLA B27
reiter syndrome
psoriatic arthritis
ankylosing spondylitis
IBD
only structure in female genital tract w/ 2 epithlium types?
cervix:
ecto –> squamocolumnear junction –> endo
ectocervix:
-stratified non-keratinized (like vagina), protrudes into vagina
endocervical canal
between external os -> internal os
-simple columnar epithelium; mucus-secreting glands
squamocolumnar junction:
squamous abrupty converts to columnar endo
histology of uterus
lined by endometrium –>
EPITHELIAL lining that proliferates and degenerates
(stratum functionalis)
reserve tissue that regenerates stratum functionalis (stratum basalis)
histology of fallopian tubes
simple ciliated columnar epithlelium
histology of ovaries
covered externally by simple cuboidal epthelium that ruptures w/ each ovulation
most common cause of infectious meningitis in patients w. AIDS
cryptococcos neoformans
amphotericin B toxicity
NEPHROTOXIC
hypokalemia
hypomagnesmia
rental tubular acidosis
kaposi sarcoma vs. bacillary angiomatosis
kaposi: HHV-8
- lymphocytic infiltrate
bacillary angiomatosis: bartonella hensela
- neutrophilic infiltrate
small cell carcinoma secreting ADH causes
free water retention –> HYPONATREMIA to try to rid of water
squamous cell carcinoma paraneoplastic syndrome
PTHrP –> hypercalcemia
hypercalcemia + tumor, consider
humoral hypercalcemia of malignancy
PTHrP-secreting paraneoplastic syndrome
presentation of hypercalcemia
fatigue, mental status change, dehydration, nephrolithiasis
can cause polyuria, polydypsia, and dilute urine (like nephrogenic diabetes insipidus) bc impairs renal concentrating ability
short peptide medication that is an analog of carboxyl terminal of delta chain of fibrinogen
abcixamab, eptifibatide, tirofiban
eptifibatide
(like abcixamab) GpIIbIIIa blocker (integrin)
binds to fibrinogen binding site
tirofiban
like abcixamab
GpIIbIIIa blocker (integrin)
ticlopidine / clopidergrel bind..
ADP-receptors
GPCRs
clopidergel activation requires
is a prodrug
must be activated by hepatic cytochrome P-450 enzyme system
*note intxn w/ P450 inhibitors etc
zero-order kinetic metabolism
rate of enzymatic rxn independent of concentration of substrate
constant AMOUNT of substrate converted to product over time
