4.56

Question 1

Prion diseases are

Answer 1

rare, fatal, rapidly progressive neurodegenerative

diseases that occur in humans and other animal species

Question 2

Prion diseases

Presence of small — within the neuropil, which produces a — appearance

Answer 2

vacuoles

spongiform

Question 3

Neuropil:

Answer 3

The complex net of
axonal, dendritic, and glial
branchings that forms the bulk
of the central nervous system
gray matter of the brain and in
which the nerve cell bodies are
embedded

Question 4

Disease: Bovine spongiform encephalopathy

Animals affected:

Answer 4

cattle

Question 5

Disease: Scrapie

Animals affected:

Answer 5

sheep and goats

Question 6

Human Prion Diseases (5)

Answer 6

Kuru
Creutzfeldt-Jakob disease (CJD)
Variant Creutzfeldt-Jakob disease (Variant CJD)
Gerstmann-Sträussler-Scheinker syndrome (GSS)
Fatal familial insomnia (FFI)

Question 7

Scrapie -

Answer 7

fatal neurodegenerative disease of sheep

Question 8

Scrapie

demonstrated to be a — disorder

Answer 8

transmissible

Question 9

CJD -

Answer 9

fatal neurodegenerative disease of humans recognized since the 1920s
demonstrated to be transmissible in the 1960s (humans to chimpanzees)

Question 10

CJD

Early symptoms:

Answer 10

memory problems, behavioral changes, poor coordination, and visual
disturbances

Question 11

CJD
Later symptoms: (5)
—% of people die within 1 year of diagnosis

Answer 11

dementia, involuntary movements, blindness, weakness, and coma
70

Question 12

Search for slow viruses that were expected to be the infectious agents of scrapie and CJD
infectious agents were “—” meaning

Answer 12

filterable

not cellular (filters used could trap bacteria)
therefore, possibly a virus

Question 13

Search for slow viruses that were expected to be the infectious agents of scrapie and CJD
Researchers treated the infectious material to determine what it was composed of (3)

Answer 13

ionizing radiation, which destroys DNA and RNA, did not affect transmission of scrapie and CJD

Question 14

Hypothesis (1960s): scrapie and CJD are caused by infectious agents consisting solely of

Answer 14

proteins

Question 15

The term “Prion” (2)

Answer 15

coined in 1982 (Stanley Prusiner; 1997 Nobel prize)

Proteinaceous, infectious

Question 16

PrPSc

Answer 16

(=PrP folded into the prion form) recruits PrP (the non-prion form of PrP) to adopt the prion shape.

Question 17

The non-prion form (“normal” form) is called

Answer 17

PrP or PrPC.

Question 18

PRNP gene on chromosome 20 encodes

Answer 18

PrP protein

Question 19

PrP polymorphism:

Answer 19

Met or Val at codon 129 of PRNP gene
60% Met codon; 40% Val codon
homozygote for either = increased risk of disease

Question 20

PrPSc is resistant to — and

accumulates in —

Answer 20

degradation

amyloid fibrils

Question 21

PrPC is strongly expressed in both (2) of the CNS and appears to regulate

Answer 21

neurons and glial cells

ion channels and neurotransmitter receptors at the pre- and postsynaptic levels.

Question 22

Characteristic: Median age at death
CJD:
Variant CJD:

Answer 22

68 years

28 years

Question 23

Characteristic: Median duration of illness
CJD:
Variant CJD:

Answer 23

4-5 months

13-14 months

Question 24

Characteristic: Clinical signs and symptoms
CJD:
Variant CJD:

Answer 24

Dementia; early neurologic signs
Promionent psychiatric/behavioral symptoms;
painful dysthesias; delayed neurologic signs

Question 25

Characteristic: Accumulation of PrPSC in brain tissue
CJD:
Variant CJD:

Answer 25

Variable accumulation

marked accumulation

Question 26

Prions may not be inactivated by means of

Answer 26

routine surgical instrument sterilization

procedures.

Question 27

The World health Organization and the US Centers for Disease Control and Prevention
recommend that instrumentation used in such cases be

Answer 27

immediately destroyed after use.

Question 28

Secondary to destruction, it is recommended that (2) decontamination be
used in combination to process instruments that come in contact with high-infectivity
tissues.

Answer 28

heat and chemical

Question 29

No cases of iatrogenic transmission of CJD have been reported subsequent to the

Answer 29

adoption

of current sterilization procedures, or since 1976.