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