|Gehrig in his heyday|
Mar 1, 2014 — Here in the U.S., the fatal neurodegenerative disease amyotrophic lateral sclerosis (ALS) is called Lou Gehrig's disease. Gehrig, a member of the Baseball Hall of Fame, was a first baseman for the N.Y. Yankees. Known as the Iron Horse, he set a longstanding record for most consecutive games played (2,130). Gehrig had to retire when he began to develop symptoms of ALS and died two years later in 1941. He was only 37 years old.
ALS is characterized by a rapidly progressive weakness, muscular and nervous degeneration, resulting in increasing difficulty in speaking, swallowing or breathing. Most people with ALS die from respiratory failure, usually within three to five years from the onset of symptoms. The median survival time from onset to death is around 39 months, and only 4 percent survive longer than 10 years.
Now, a study led by University of British Columbia and Vancouver Coastal Health Research Institute researchers has revealed how ALS is transmitted from cell to cell, and suggests the spread of the disease can be blocked.
"This work identifies an important piece of the puzzle in determining how the disease is transmitted throughout the nervous system," says lead investigator Dr. Neil Cashman. "By understanding how this occurs, we can devise the best ways to stop the progressive neurological damage seen in ALS."
The research shows that misfolded non-mutant superoxide dismutase 1 (SOD1) can be transmitted from region to region in the nervous system, offering a molecular explanation for the progressive spread of ALS. SOD1 binds copper and zinc ions and is one of three superoxide dismutases responsible for destroying free superoxide radicals in the body.
Published in the Proceedings of the National Academy of Sciences, the study also shows the spread can be blocked using antibodies. Antibodies were specifically raised to bind to regions of SOD1 exposed when it is misfolded, and block its spread. If non-mutant SOD1 misfolding is the cause of ALS, as the study suggests, then the antibodies could arrest ALS progression, the researchers say.
ALS is associated with mutant SOD1 protein (superoxide dismutase 1) and earlier investigations in Cashman's lab found that the disease-associated mutant SOD1 can induce a change in the shape of other, non-mutant proteins. The affected proteins then accumulate in ways similar to the process underlying prion diseases – rare, fatal, degenerative brain disorders seen in both humans and animals.
ALS affects nerve cells in the brain and the spinal cord. Motor neurons progressively degenerate and die so that the brain can no longer initiate and control muscle movement. Patients in the later stages of the disease may become totally paralyzed. There are approximately 140,000 new cases of ALS diagnosed worldwide each year.
Prion diseases belong to the general category of brain diseases called proteinopathies, which also includes Alzheimer's disease and Parkinson's disease. The most common human form of prion disease is Creutzfeldt-Jakob disease (CJD).
Prion diseases of animals include Bovine Spongiform Encephalopathy (BSE) (mad cow disease) in cattle, scrapie in sheep and goats, and Chronic Wasting Disease (CWD) in deer and elk.
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