Lecture 1 Flashcards
What does misfolding process trigger?
Self-association
What does self-association of proteins create?
Long amyloid plaques
What are proteins described as?
Living on a knife edge
Is the energy difference between folded and unfolded state huge?
No
What is the stability associated with a protein around?
5-15kcal/mol
What is one single hydrogen bond around?
2-5kcal/mol
How many hydrogen bonds does a medium sized protein have?
400-500 hydrogen bonds
What are Misfolding diseases a losing battle between?
Deposition and clearance
How many identified proteins are there that have caused different protein misfolding diseases?
24
What can diseases of amyloidosis be?
Local
Systemic
What is meant by local?
Restricted to a single organ e.g. brain
What is meant by systemic?
Protein aggregates can form across the whole body
What is half of your body mass?
A single aggregated protein
What are prions?
A group of conditions that affect the nervous system
Definition of prion
Collection of proteins which normally exist in our body but have misfolded and form insoluble aggregates
What does aggregation of proteins cause?
Death of cells
What is a PrP protein?
Normal protein found in the brain and under certain conditions e.g. mutation this protein will actually misfolding into protein PrPSC
What does PrP protein consist predominantly of?
Alpha helices
What does PrPSC have a higher proportion of?
Beta pleated sheets
What occurs during misfolding process?
Instead of forming all the alpha helices we form the beta pleated sheets
What does beta pleated sheets consist of?
Linear polymers that stack on top of one another - greater potential of bonding to other beta pleated sheets via non covalent bonds therefore forming aggregates
What are spongiform Encephalopathies prion disease?
Disease are fatal
No cure for them
What does spongiform refer to?
Characteristic appearance of infected brains which become filled with holes until they resemble sponges when examined under microscope
From early symptoms, when does the patient die?
Within a year
What are the neuropathology of Spongiform Encephalopathies prion disease?
Spongiform degradation of the brain
The brain shrinks and become spongy
Leaves holes in the white and grey matter of the brain
What are aggregation of proteins called?
Amyloid plaques
What is the property of protein plaque?
Resistant to proteolytic degradation
What can prion diseases be?
Inheritable
Sporadic
Infectious
What are prions a devoid of?
Nucleic acid
When does cellular PrP converted into PrPSC?
When a portion of alpha-helical and coil structure is refolded into B-sheets
What is an example of sporadic disease?
Creutzfeldt-Jakob disease (CJD)
What is CJD?
Rare, degenerative fatal brain disorder
What are early stages of disease people may have of CJD?
Failing memory
Behavioural changes
Lack of coordination
Visual disturbances
What happens with patients that have CJD as illness progresses?
Mental deterioration Involuntary movements Blindness Weakness of extremities Coma
What is Gertsmann-Straussler-Scheinker?
A type of prion disease
What is familial CJD?
Inherited form of CJD
Result from several types of mutation on prion gene
What is fatal familial insomnia?
Very rare sleep disorder that runs in families
Affects the thalamus
What does the thalamus control?
Emotional expression and sleep
What is main symptom of FFI?
Insomnia
Speech problems and dementia
Where did TSE come from?
Isolated tribe
The Fore-tribes-people in New Guinea
What is Kuru?
‘The trembling’
Neurodegenerative disease that gave a tremor
Rare and fatal nervous system disease
How did the fore people contract the disease?
Performing cannibalism on corpses during funeral rituals
What are the symptoms of disease of Kuru?
Muscle twitching Loss of coordination Difficulty walking Involuntary movements Behavioural and mood changes Dementia Difficulty eating
What caused kuru?
The link between ritualistic cannibalism and kuru was a long incubation period (5 and 30 years)
What is cannibalism?
The practice of humans eating the flesh or internal organs of other human beings
What is Iatrogenic CJD?
Form of CJD which belong to a group of rare, fatal brain disorder called prion disease
Arises from contamination with tissue from an infected person - medical procedure
How has CJD been transmitted?
Treatment with human growth hormone
Peripheral transmission
Human growth hormone
Treat children with short stature
Prepared from human pituitary gland
What is the incubation for transmitting with HGH?
3 and 20 years
Cornea and other grafts
Incubation 1 to 14 years
Scrapie in sheep
Most widespread form of TSE
Transmissible and inheritable component to spongiform Encephalopathies
Infectious but certain breeds are more prone to diseases
What is scrapie agent extremely resistant to?
Inactivation by UV and ionizing radiation
Is scrapie transmitted to humans?
No
How many cattle’s died from BSE?
> 160,000
How long does it take for symptoms of BSE to appear?
5 years
How many were infected with BSE?
1 million
What other animals did mad cow disease spread to?
Mink
Mule
Deer
Cats
What is mad cow disease?
Neurodegenerative disease that can mutate and spread to humans
What causes mad cow disease?
Feeding cattle the remains of infected cows
What are the human symptoms of mad cow disease ?
Depression
Apathy or anxiety
Difficulty walking and controlling their limbs
What are the animal symptoms of mad cow disease?
Increasingly aggressive
Lose control of movement
Milk production stops
Anorexia and legarthy
Sunday times, May 1990
Leading food scientist calls for slaughter of 6 million cows
The UK government does not agree with him
He is accused of ‘scare-mongering’
Daily Mirror, March 96
MAD COW CAN KILL YOU
Times June 96
Scientist find direct evidence for BSE link
A French group injected macaque monkeys with BSE the pathology that was produced in their brain very similar to that found with patients that have died recently with vCJD
Oct 1996
The European Union has banned imports of British Beef
McDonald’s has pulled British Big Macs from its menu
New variant CJD
Only observed in UK and France
Teenagers and young adults
~170 deaths
What is new variant CJD linked to?
Infected beef and the mad cow epidemic
What does recent work of new variant CJD show?
Mother to baby transmission
Blood transfusion: blood donor restrictions
What is vCJD not clustered to?
Particular area of UK