Rare Diseases News Briefs for Week of January 7, 2001
Progress in Alzheimer's disease research: toxic amino acid identified, potent vaccine developed (in mice), low-dose anti-inflammatory drugs offer protection
Researchers Identify Promising Target To Slow
Alzheimer's
Science
Daily, December 21, 2000
HONOLULU, Dec. 18 - Researchers believe that a chemical called methionine plays a role in Alzheimer's disease and also could explain how vitamin E slows the progress of the disease in its later stages. The finding could lead to new drugs to delay the advance of Alzheimer's, say the researchers, who presented their study today during the 2000 International Chemical Congress of Pacific Basin Societies.
Alzheimer's is a chronic form of dementia that primarily strikes the elderly and causes severe memory loss and, eventually, death. The disease is characterized by the overproduction of a protein, beta-amyloid, that accumulates in the brain of its victims. Although normal brains contain beta-amyloid, those with the disease have comparatively large amounts. The protein is thought to produce chemicals called free radicals, which are toxic to the brain, according to the study's lead researcher, Allan Butterfield, Ph.D., a professor of chemistry and director of the Center for Membrane Sciences at the University of Kentucky in Lexington.
Butterfield examined the sequence of amino acids in beta-amyloid and found that one in particular - methionine - is the likely source of the toxic free radicals.
Recent studies have demonstrated that higher than normal doses of vitamin E may slow the advance of Alzheimer's in some people with late stages of the disease. The current study provides a possible explanation for this link. Vitamin E, an antioxidant, appears to work by destroying free radicals (oxidants) produced by amyloid, says Butterfield.
About.com Guide to Alzheimer's - site devoted to the disease and its issues
University Of Toronto Researchers Develop Potent
Vaccine For Alzheimer's
Science
Daily, December 20, 2000
Researchers in the University of Toronto's Faculty of Medicine have discovered that a vaccine may help prevent and treat the disabling memory loss and cognitive impairment (dementia) of Alzheimer's disease.
Alzheimer's occurs when toxic biochemical compounds known as amyloid ß peptides accumulate in the brain, forming amyloid plaque deposits and injuring nerve cells, eventually causing dementia. While previous studies have shown that vaccinating transgenic mice with this peptide could remove the amyloid plaques, there was never any evidence of improvement in brain function.
After developing transgenic mice with amyloid plaques and cognitive impairment similar to those found in human Alzheimer's, scientists at U of T's Centre for Research in Neurodegenerative Diseases (CRND) determined that immunization with amyloid ß peptides blocked both the production of the plaques and learning impairment.
"Not only were we able to clean up the brain tissue, but we also prevented the behavioural consequences of Alzheimer's," says Dr. Peter St George-Hyslop, director of the CRND and a neurologist at the University Health Network. "Obviously, it is more important that a treatment or prevention in humans be able to block the clinical dementia."
The researchers believe this study provides the final element of proof that Alzheimer's is initiated by amyloid ß peptides.
For more on this discovery, visit http://www.newsandevents.utoronto.ca/bin1/001220a.asp
About.com Guide to Alzheimer's - site devoted to the disease and its issues
Low-Dose Anti-Inflammatory Drugs Protect Against Alzheimer's
Disease
Reuters Medical News, November 21, 2000
WESTPORT, CT (Reuters Health) Nov 21 - The apparent protective effect of anti-inflammatory drugs against Alzheimer's disease is unrelated to the dose of the anti-inflammatory agents used, according to researchers in Australia. In fact, low-dose anti-inflammatory drugs have the same benefit as do high-dose agents.
Investigators examined the effects of anti-inflammatory drugs on the risk of Alzheimer's disease and other forms of dementia in patients enrolled in the Sydney Older Persons Study. Participants who took anti-inflammatory medication were less likely to develop Alzheimer's than those who did not. The results suggest that even the low anti-inflammatory doses used to lower cardiovascular risk can help protect elderly patients against Alzheimer's.
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