Prions
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19 terms
Terms | Definitions |
|---|---|
 what are prion diseases caused by? | -not virus, bacteria, fungus or parasites -caused by variation in conformation of normal cellular protein in CNS -may start with into of foreign homologue from humans or other animals like cows -can also initiate by chance or genetic predisposition |
| what is a prion? | proteinaceous infectious particle -no evidence of inflammation/antibody response to infection with prions -preclinical period lasts months to years |
| prions are resistant to... | UV ionizing radiation formaldehyde proteases |
| what are prions sensitive to? | -protein denaturing agents phenol urea guanidine HCL NaOH |
| best studied prion? | causes scrapie in sheep |
| describe the proposed molecular disease process for prions: | -PrPsc causes molecule switch of cellular protein PrPc to the prion conformation. -altered protein cannot be degraded by cellular proteases and accumulates in cytoplasm and extracellular areas of cells in brain -could be caused by mutation in gene encoding for PrP protein (random or by ingesting PrPsc protein from another source) |
| what is PrPsc? | protease resistant prion protein |
| describe Kuru: | -New Guinea-transmitted by brain of dead people during prep for ritual cannibalism |
| Gerstmann-Straussler Scheinker Syndrome (GSS): | -prion protein mutation of P102L and others |
| Creutzfeldt-Jakob Disease: | -high prevalence found in Jewish Libyans, but found all over the world -can be sporadic, passed via human tissue transplantation or hereditary (mutation in PrP) -mean age of onset is 63 years -transmission by grafts of dura mater during neurosurgery (incubation is 7years) -3.1 pts per million people -can occur by random misfolding of the protein |
| describe Fatal Familial Insomnia: | -severe atrophy of anterior, ventral and mediodorsal thalamic nuclei -leads to insomnia and death |
| variant CJD? | -most like from Bovine Spongiform Encephalopathy (animal disease) -first in the UK -linked to ingestion of contaminated beef 153 reported cases -long incubation period -related to eating British beef -earlier onset than regular CJD (many pts in their 20s) -amyloid plaques -prolonged illness -psych. sx -prominent ataxia -early signs are irritability and memory loss and dementia (rapidly progressive), blindness, myoatrophy -Prodromal=vague symptoms -late sx-pt mute and demented and jerking often disappears -over 80% die within 12 months of sx -only 1 case in the US that was confirmed to have originated in the UK |
| which of these are genetic disorders? | CJD (not always), FFI and GSS |
| describe scrapie | -causes disease in sheep -progressive and fatal neuropathy -loss of wool and scrape vs things to aid the process |
| describe bovine spongiform encephalopathy (BSE) | -progressive neuro disorder in cattle -leads to tremors, staggering and death -mad cow disease -first appeared in england 1986 |
| describe chronic wasting disease (CWD) | -deer and elk -weight loss and neuro sx that lead to death -concetrated to wyoming, CO and a little in michigan/new mexico |
| pathoogy of vCJD: | -CSF normal, no inflammation -cerebral atrophy, neuronal loss, vacuoles in neurons with proteinaceus granules -infected cells have fibrils resembling amyloid that consist of PrP -note that all those diagnosed with vCJD are homozygous for methionine at position 129 of the PrP gene |
| incidence of position 129 of PRP gene? | MET/VAL =50% MET/MET= 40% VAL/VAL= 10% |
| how to disinfect stuff if you think CDJ or VCJD is on it? | use 1N NaOH for 1 hour and autoclave at 134 OR 2N NaOH if you can't autoclave |
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