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| | ==Prion Diseases== | | ==Prion Diseases== |
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| − | * Prion diseases are also knowns as transmissible spongiform encephalopathies (TSEs).
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| − | * They are a group of fatal neurodegenerative diseases which occur in a number of species, including man.
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| − | ** For example:
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| − | *** Bovine spongiform encephalopathy (BSE) in cattle
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| − | *** Scrapie in sheep
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| − | *** Chronic wasting disease in elk
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| − | *** Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), fatal familial insomnia (FFI) and kuru in man
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| − | * TSEs have a long incubation period, making them difficult to diagnose.
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| − | ===Aetiology===
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| − | * The aetiology of prion diseases is still highly controversial.
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| − | ** However, an abnormal isoform of the host-encoded prion protein (PrP) is seen in the brains of affected animals.
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| − | *** The normal host PrP changes its structure into the disease-associated form PrPSc.
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| − | ** The abnormal proteint (PrPSc) accumulates as amyloid fibrils in nervous tissue.
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| − | * The agent appears to be highly resistant.
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| − | ===Pathology===
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| − | ====Gross====
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| − | * Prion diseases cause NO GROSS LESIONS.
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| − | ====Hisological====
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| − | * TSEs typically cause what is known as the "microscopic triad":
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| − | *# Spongiform change.
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| − | *#* Vacuolation of neurons.
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| − | *#* Particularly in nuclei.
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| − | *# Astrogliosis
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| − | *# Amyloid plaques
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| − | *#* These are not always seen.
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| | ==Non-Infectious Inflammatory Diseases== | | ==Non-Infectious Inflammatory Diseases== |