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From New Scientist, 19
June 1999
THE ABNORMAL PROTEIN deposits that
clog the brains of Alzheimer's patients probably damage
nerve cells by producing the toxic chemical hydrogen
peroxide, new research suggests. Experts say this raises
hopes that it might be possible to treat the disease by
blocking this fairly simple chemical.
In Alzheimer's disease, an abnormal form of beta-amyloid
protein forms in the brain. Scientists already knew that
cells containing this protein also have raised levels of
the powerful oxidising agent hydrogen peroxide. However,
it was unclear why this was. To find out more, scientists
from Harvard Medical School and the University of
Heidelberg looked at the chemical reactions in these
cells by studying changes in the way they absorbed light
and fluoresced.
The researchers discovered that when abnormal beta-amyloid
binds to iron and copper, the metal ions donate electrons
to dissolved oxygen (Biochemistry, vol 99, p 438).
Oxygen molecules with two excess negative charges then
react with hydrogen ions to form hydrogen peroxide. The
team also showed that the type of beta-amyloid associated
with the most aggressive form of Alzheimer's was the best
at binding copper and iron--and hence at generating
peroxide--suggesting that this reaction is a major factor
in causing the brain damage.
"Ultimately we would like to be able to interrupt
this process," says team member Ashley Bush of
Harvard Medical School in Charlestown, Massachusetts.
"The sites where the copper and iron bind could be
an easy targetout the three-dimensional structure of the
binding site.
." He adds that scientists will first need to figure
The new evidence that the generation of peroxide may be
involved in the disease process fits in with other
observations, Bush says. Earlier studies showed that
antioxidants such as vitamin E offer significant
protection to people who are developing Alzheimer's.
Lowering heart disease risk.
Scientists at Cambridge University gave 2,000 cardiac patients a daily Vitamin E supplement which reduced their risk of non-fatal heart attacks by 75%;
Boosting fertility.
Daily Vitamin C reduced genetic abnormalities in sperm of heavy smokers. Daily Vitamin E improves the ability of sperm to attach to the egg. Low levels of selenium are associated with increased risk of miscarriage.
Skin protection.
Results show that caratenoids increase sun protection. Another study shows anti-oxidants applied in sunscreen may slow wrinkle formation.
A healthy pregnancy.
Studies have shown a link between poor anti-oxidant status and a high risk of pre-eclampsia.
Reducing cancer risk.University of California reports those with high intakes of anti-oxidants are half as likely to get cancer. Arizona Cancer Centre found skin cancer patients on daily supplement of selenium reduced risk of dying from cancer by half.
Boosting immunity.
Beta carotine and Vit. C increase efficiency of killer cells. Low selenium levels in HIV patients increase risk of developing aids. Vitamin E offsets many age-related declines in immunity.
Preventing eye disease.
Carotinoids can thicken the macular pigment of the retina. Harvard University reports Vitamin C supplements reduce risk of cataracts by 83% over 10 years.
Improving lung function.
St Thomas's Hospital reports high pollution in London compromises anti-oxidant status of epithelial lining fluid. Vitamins E and C benefit asthmatics exposed to pollution.
Protect from exercise damage.
Regular exercise makes you breathe deeper which means you take in more oxygen which produces oxidants which cause muscle damage.
Counteracting a fatty diet.
After a high-fat meal the level of blood fats in blood vessel walls increases. It does not increase after either a low-fat meal or a high-fat meal with added anti-oxidants.