Mad Cow Disease and Variant

Creutzfeldt-Jakob Disease

Understanding the Brain: The Neurobiology of

Everyday Life

Final Project by Amalia Martínez Avalos

MAD COW DISEASE

Medically known as Bovine Spongiform Encephalopathy (BSE), affects the central nervous system (CNS) of cattle

Belongs to a group of Transmissible Spongiform Encephalopathies (TSE).

This is a group of neurodegenerative disorders that affect animals and humans

The name Mad Cow Disease refers to the signs of infected cattle:

◦ staggering,

◦ drooling,

◦ signs of fear,

◦ grinding of teeth,

◦ aggression toward other animals

Mad Cow Disease

The disease was first diagnosed in the

United Kingdom in 1986.

Infected adult cattle may develop signs of

the disease slowly (2 to 8 years):

◦ change in attitude and behavior

◦ gradual uncoordinated movements

◦ trouble standing and walking

◦ Weight loss

◦ Eventually the animal dies

How cattle develop Mad Cow

Disease Feed is the major route for transmission

among cattle

When cattle are feed with products made

from other cattle or sheep, they are

recycling diseased animal protein in feed

containing meat and bone meal, thus

causing the disease in cattle.

Mad Cow Disease: Zoonotic

importance A human version of Mad Cow Disease

called variant Creutzfeldt-Jakob disease

(vCJD) is believed to be caused by eating

beef infected with bovine spongiform

encephalopathy (BSE), products

contaminated with central nervous

system tissue

Creutzfeldt-Jakob Disease

(CJD) It is important to clarify the differences between

variant CJD and another form of the disease, referred to as classic or sporadic CJD.

Classic CJD is not linked to eating nerve tissue from mad cow disease-affected cattle and it may be caused by; SPORADICALLY. CJD that occurs without explanation is

termed spontaneous CJD or sporadic CJD and accounts for the majority of cases.

INHERITANCE. In the United States, about 5 to 10 percent of people with CJD have a family history of the disease.

IATROGENIC. A small number of people have developed CJD after being exposed to infected human tissue during a medical procedure, such as a cornea or skin transplant

Classic CJD most commonly affects people over 65 and is usually fatal within six months from onset of symptoms

Variant Creutzfeldt-Jakob

Disease: characteristics Difference between variantCJD and classic

CJD

younger age of onset, (lower than 29 years vs.65

yeears in classicCJD classic)

lack of characteristic EEG findings,

longer course of disease,

and more extensive spongiform change

with plaques in the brains of affected

persons.

Causitative agent

Researchers believe that the infectious

agent that causes mad cow disease and

and Variant Creutzfeldt-Jakob

Disease is an abnormal version of a

protein normally found on cell surfaces,

called a prion

For reasons still unknown, this protein

becomes altered and destroys nervous

system tissue (brain and spinal cord).

PRION

Is a type of protein

“prion” : neologism deriving from the words “protein” and “infection”

Prion proteins occur in: ◦ a normal form, which is a harmless protein found in the

body’s cells

◦ an infectious form, which causes disease

◦ Both forms of the prion protein have the same sequence of amino acids

◦ the infectious form of the protein takes a different folded shape than the normal protein.

◦ Diseases may develop because some normal prions spontaneously change into the infectious form of the protein and then alter the prions in other cells in a chain reaction.

hPrions, can take on two different

conformations

The prion on the right, in a helical conformation, dissolves easily in water and is relatively

benign.

The prion on the left, in a beta-sheet conformation, tends to stick to other similar prions and

forms plaques.

These plaques disrupt the structure of healthy tissue, resulting in the "spongy" texture found in

the brains of infected

Pathogenesis of vCJD

Infected Beef eaten by humans Not affected by cooking

After the ingestion of prion it passes through the lymphoid formations of the intestine (Peyer plaques) where it can be replicated

transported along nerve fibers at a rhythmus one millimeter by day

reaches the spinal cord and the brain

In the brain stem prions accumulate and convert normal prion proteins to the disease-causing form PrPSc.

Years later, spongiform encephalopathy results when a sufficient number of nerve cells have become damaged

Causes the characteristic lesions

Histological Findings on Post

Mortem Bovine Spongiform Encephalopathy (BSE) is so named because of the spongy

appearance of the brain tissue of infected cattle (and also in the human beings)

when sections are examined under a microscope

Variant CJD in humans: section of cerebral cortex stained to show aggregates of PrPSc within plaques and more finely distributed throughout the grey matter (Prion Proteins stains brown)

Histological Findings on Post

Mortem

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A characteristic feature of variant Creutzfeldt–Jakob disease is the presence of “florid plaques”

composed of a core of PrPSc amyloid surrounded by vacuoles { variant Creutzfeldt–Jakob disease is

distinguished by the abundance of PrP amyloid plaques, which are often surrounded by a halo of

intense vacuolation.

Neurologycal symptoms of vCJD Initial neurogycal symptoms

severe depression

intense feelings of despair

withdrawal from your family, friends and the world around you

anxiety

irritability

difficulties sleeping

Advanced neurological symptoms:

loss of physical co-ordination, which can affect a wide range of functions, such as walking, speaking and balance (ataxia)

muscle twitches and spasms (myoclonus)

loss of bladder control and bowel control

blindness

swallowing difficulties (dysphasia)

loss of speech

loss of voluntary movement (akinesia)

Advanced psychological symptoms

loss of memory, which is often severe

problems concentrating

confusion

feeling agitated

aggressive behaviour

loss of appetite,

paranoia, which is when you feel that people are secretly out to harm you

unusual and inappropriate emotional responses, such as laughing when you hear bad news or bursting into tears for no apparent reason

Final stages

The disease usually runs its course in about

seven months, although a few people may live

up to one or two years after diagnosis.

Totally unaware of their surroundings and need

of totally care.

Lost of the ability to speak.

Death usually in one of two ways:

◦ due to infection –pneumonia

◦ due to respiratory failure

Affected regions of the brain Being a neurodegenerative desease multiple regions of the brain are affeected

Frontal Lobe: creative thought, problem solving, intellect, judgment, behavior, attention, abstract thinking, physical reactions, muscle movements, coordinated movements, smell and personality.

Parietal Lobe: Visual functions, language, reading, internal stimuli, tactile sensation and sensory comprehension will be monitored here.

Motor Cortex- monitor and control movement throughout the body.

Temporal Lobe: The temporal lobe controls visual and auditory memories. It includes areas that help manage some speech and hearing capabilities, behavioral elements, and language. It is located in the cerebral hemisphere.

Occipital Lobe: The optical lobe is located in the cerebral hemisphere in the back of the head. It helps to control vision.

Cerebellum balance, posture and coordination, allowing humans to move properly and maintain their structure.

Amygdala: to emotions, memories and fear.

Hippocampus: memory, specifically converting temporary memories patial relationships, for accurate movements

Hypothalamus: mood, thirst, hunger and temperature.

cerebral peduncle which allows voluntary motor function to take place.

Pons: sensory analysis or motor control sleep.

Medulla: vital body functions such as the heart rate and breathing.

Medically known as Bovine Spongiform

Encephalopathy (BSE), this ailment affects the

central nervous system (CNS) of cattle. Mad

cow disease belongs to a group of

Transmissible Spongiform Encephalopathies

(TSE). This is a group of neurodegenerative

disorders that affect animals and humans

Read more at

Buzzle: http://www.buzzle.com/articles/mad-

cow-disease-symptoms.html

DIAGNOSIS

only in advanced stages of the disease can

brain abnormalities be detected by MRI

(magnetic resonance imaging). vCJD is

fatal, usually within 13 months of the

onset of symptoms.

DIFERENTIAL DIAGNOSIS

vCJD must be differenciated from:

Alzheimer

Huntington

Treatments

No effective treatment exists for

Creutzfeldt-Jakob disease or any of its

variants

palleative care alleviating pain and other

symptoms

Prevention

Prions are incredibly resistant to heat, chemicals, and even radiation.

The United States Department of Agriculturee and the Food and Drug Administration (USDA & FDA) take a number of measures in three areas to counter the Mad Cow threat:

1. Restrictions on the import of cattle and cattle products from the U.K. and other countries with BSE or at risk of BSE;

2. Testing cattle brains for BSE; and

3. A rule intended to prevent the feeding of cattle, sheep or goats parts to cattle.

My personal experience analizing

events around me. In this course, learning about the neurobiology of

each day in my life has allowed be to better realize how I exist. Now I begin to understand the complex interaction between me, my being and the out world. This course made me realize the little, the small an apparently insignificance of neurons and their relation to the universe of being alive and living experiences. More than an academic course it has been to me a personal experience with myself.

As I m learning or trying to memorise events I imagine how the information is moving around the regions of my brain involved

Consulteed bibliogrphy

http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm

http://www.millerandlevine.com/news/bse/

http://www.mayoclinic.org/diseases-conditions/creutzfeldt-jakob-

disease/basics/treatment/con-20028005

http://www.nhs.uk/Conditions/Creutzfeldt-Jakob-disease/Pages/Symptoms.aspx

http://zl.elsevier.es/es/revista/radiologia-119/enfermedad-creutzfeldt-jakob-

hallazgos-resonancia-magnetica-13142171-originales-2009

Johnson RT. Prion diseases. Lancet Neurol. 2005;4:635-642.

Creutzfeldt-Jakob diseaseDifferential diagnosis Raymond P Roos

MDhttp://www.medmerits.com/index.php/article/creutzfeldt_jakob_disease/P8

http://www.buzzle.com/articles/mad-cow-disease-symptoms.html

http://www.nhs.uk/Conditions/Creutzfeldt-Jakob-disease/Pages/Symptoms.aspx