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path 310 > creutzfeldt-jakob disease (prion-based disorders) > Flashcards

creutzfeldt-jakob disease (prion-based disorders) Flashcards

1
Q

describe the first discovery of prion diseases

A
  • in Kuru
  • found that there was a pre-clinical stage and 3 clinical stages (ambulent, sedentary, terminal)
  • found that it mostly affected women
  • classified by spongiform encephalopathy and plaques
  • did not cause inflammation
  • was tied to canabolism at the time
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2
Q

prion diseases are also known as:

A

transmissible spongiform encephalopathies (TSEs)

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3
Q

prion diseases are rare or common? what is the prognosis of this type of disease?

A
  • rare

- fatal - may not appear for a bit but then progesses very fast

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4
Q

what type of disease is this?

A

neurodegenrative

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5
Q

what is the prion gene and where is it encoded?
what is the normal cellular protein this gene produces?
what is the function of this protein?

A
  • PNRP - chromosome p20
  • produces prp
  • thought to be involved in maintaining synapses or synaptogenesis (function is unknown)
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6
Q

how do prion diseases come about?

A

the prion protein misfolds, resulting in protein deposition in the brain, causing the progressive neurological disorder

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7
Q

how do prion diseases propagate?

A

by transmitting conformational changes within the prion protein

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8
Q

are prion proteins highly or barely conserved among species?

A

highly

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9
Q

describe the non-pathological prion protein (PrP)

A
  • rich in alpha helicies
  • protease sensitive
  • detergent soluble
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10
Q

describe the pathogenic prion protein (PrPSc)

A
  • rich in beta sheets
  • protease resistant
  • insoluble
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11
Q

what are the three ways in which a conformational change within a prion protein can manifest?

A

(1) infectious PrPSc
(2) mutation PrPM
(3) sporadic PrPSc

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12
Q

describe infectious PrPSc

A
  • 1%
  • if a patient is exposed to the pathogenetically folded prion protein it will cause the proteins that dont have the conformation to assume that conformation
  • once this begins there is continuous cascade of pathogenesis
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13
Q

describe mutation PrPM

A
  • 15%
  • conformational changes within the prion protein can be genetic
  • this means there’s a change in the aa seq that results in an increased susceptibility to form misfolded proteins
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14
Q

describe sporadic PrPSc

A
  • 85%
  • conformational changes within the prion protein can also be sporadic
  • this means its unknown what factors cause it
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15
Q

increased presence of beta sheets found in misfolded prion proteins results in what?

A

changes to the structure of brain tissue

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16
Q

what are the pathologies associated with prion diseases? (what are the associated changes to brain tissue?) (5)

A

(1) prion deposition in the brain - can lead to other pathologies:
(2) synaptic dendrite loss
(3) spongiform encephaly - prion diseases make the brain look like a sponge (holes are produced in the brain tissue)
(4) gliolisis - proliferation of glial cells (occurs in response to (injury) the deposition of amyloid plaques)
- if this persists it leads to scarring within the brain
(5) neuronal death - can spread to other organs

17
Q

how does spongiform encephaly occur?

A
  • the formation of fibrils from prion depositions results in the formation of amyloid plaques
  • this affects dendrite and neuronal function, creating gaps
18
Q

what disease represents ~85% of all prion diseases?

A

CJD

19
Q

is there any gender predilection to CJD?

A

no

20
Q

list and describe the four subtypes of CJD

A

(1) sporadic CJD (sCJD): most common
- cause is unclear
(2) variant CJD (vCJD):
- caused by consuming contaminated meat from a cow with spongiform encephalopathy (BSE)
(3) iatrogenic CJD (iCJD): rare
- caused by a medical examination or treatment
(4) familial CJD (fCJD): rare
- mutated prion gene is passed down from patient to child

21
Q

what are the symptoms of sCJD?
how long to patients live with this disease?
what is the typical age of onset?

A
  • dementia, ataxia, myoclonus
  • <1 year
  • 61
22
Q

what are the symptoms of vCJD?
how long to patients live with this disease?
what is the typical age of onset?

A
  • behavioural changes, dementia
  • 1.5 years
  • teens/young adults
23
Q

what are the symptoms of iCJD?
how long to patients live with this disease?
what is the typical age of onset?

A
  • ataxia, dysarthria, dementia
  • 2-6 years
  • 20s-60s
24
Q

what are the symptoms of fCJD?
how long to patients live with this disease?
what is the typical age of onset?

A
  • insomnia, dysautonomia, ataxia, dementia
  • 1 year
  • 45
25
Q

what would a typically histological stain look like for sCJD?

A
  • typical spongiform degeneration of the gray matter

- reactive gliolisis

26
Q

what would a typically histological stain look like for vCJD?

A

florid plaques consisting of dense core prion deposits surrounded by vaccuoles (halo)

27
Q

what would a typically histological stain look like for iCJD?

A

large prion protein amyloid plaques

28
Q

what would a typically histological stain look like for fCJD?

A
  • neuronal loss and gliolisis in the thalamus, inferior olives of the medulla and cerebellum
  • no vacuolar degeneration
29
Q

how did we test the idea that vCJD is caused by BSE?

A
  • brain extracts of vCJD and BSE were put into mice and then treated with proteinase K and the migration patterns were examined using western blots
  • sCJD and iCJD displayed same patterns (type1-3)
  • vCJD and BSE displayed the same patterns (type 4)
30
Q

is there any cure or certified treatment available to slow the progression of prion diseases?
is early diagnosis important? why or why not?

A
  • no
  • yes
  • so family can come to terms with the diagnosis
31
Q

what is an optional experimental treatment? how does it work?

A

-oxygen therapy - uses hypoxia to increase gene expression of the non-infectious prion protein and provide beneficial effects on the affected neurons

32
Q

what can be done to confirm CJD after death?

A

autopsy:
- western blot of proteins
- brain slices can confirm via the gross anatomy of the brain (spongy, sCJD =ventricles that are more widely spaced, etc.)
- often see atrophy (dilation of the ventricles) due to the loss of neuronal matter

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