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Science
Friday > Archives
> 2000
> May
> May 12, 2000:
Hour Two: Mad Cow Disease
and CJD
| A study released last week in the U.K. failed to find
evidence that tainted beef from the "mad cow disease"
epidemic of 1996 has caused widespread illness in people. After
studying samples taken from over 3000 people, the researchers found
no signs of new variant Creutzfeldt-Jakob disease (nvCJD), which
is strongly believed to be related to bovine spongiform encephalopathy
(commonly called mad cow disease or BSE.) They reported early results
of their work in the medical journal The Lancet. |
Changes to a small portion of this protein may change
it from a normal protein to an infectious prion. (image: Inst. for
Mol. Biology and Biophysics, Swiss Federal Inst. of Technology)
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Another paper recently released in the Annals
of Neurology, however, paints a gruesome picture of the progression
of nvCJD. There is no treatment for nvCJD --doctors can simply try to
make the patient comfortable. Tracking 35 patients over a period that
averaged 14 months, the research team watched as the patients progressed
from psychiatric symptoms such as depression to neurologic symptoms, such
as coordination problems and involuntary movements. Some felt numbness
or painful sensations in their skin and limbs. As the patients neared
death, they gradually slipped into helplessness, losing the ability to
move or speak.
In both CJD, which can be inherited, can arise spontaneously,
or transmitted from person to person, and nvCJD, which is suspected
of being linked to BSE, brain tissue is gradually eaten away in a spongelike
pattern.
In 1997, Dr. Stanley Prusiner, a researcher at the University of California
at San Francisco, was awarded the Nobel Prize in medicine. His theory,
first floated in the early 1980's, was that there was an infectious
agent that was not a bacterium, not a virus, but was something else
entirely. Prusiner claimed that the new infectious particle, which he
called a "prion," was actually a rogue protein responsible for diseases
like scrapie, kuru, and BSE.
Prions, Pruisner argued, were proteins that were found normally in
animal brains - but with a twist. These proteins had somehow folded
themselves into a new shape, and could induce normal proteins that they
bumped into to link up and refold themselves as well. In this way, the
prion could itself spread through the brain, converting normal proteins
into aberrant ones, and eventually causing damage to brain tissue.
On this hour of Science Friday, we'll talk about prions, BSE, and the
links between animal diseases such as BSE and scrapie and human diseases
such as nvCJD.
Mary Jo Schmerr
Lead Scientist, Prion Diseases
National Animal Disease Center
Agricultural Research Service
United States Department of Agriculture
Ames, Iowa
Linda Detwiler
Senior Staff Veterinarian
Animal and Plant Health Inspection
Service
United States Department of Agriculture
Robinsville, New Jersey
Books/Articles Discussed:
Related Links:
Nat'l
Inst. of Neurologic Disorders and Stroke: Creutzfeldt-Jakob Disease
fact sheet
CDC:
Bovine Spongiform Encephalopathy and Creutzfeldt-Jakob Disease
National
Prion Disease Pathology Surveillance Center
UK
BSE Surveillance: Creutzfeldt-Jakob Disease
Creutzfeldt-Jakob
Disease Foundation, Inc.
Mad
Cow Disease
USDA
APHIS: Bovine Spongiform Encephalopathy
Scientific
American: The Prion Diseases
Produced By: Karin Vergoth
Web Producer: Charles
Bergquist
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