Health Report

THE GOOD NEWS

-- A physical mechanism linking heart attacks and stress may have been found, a discovery that could ultimately help prevent heart attacks. Mental stress seems to make blood platelets release the chemical atp into the bloodstream, and atp produces blood clots, a major cause of heart attacks.

-- First "good" cholesterol, now "good" fat. A type of body fat has been found that, paradoxically, protects against obesity. Mice bred to have a deficit of "brown fat" gain a great deal of weight very quickly when fed a normal diet. Researchers believe that the brown fat, which is also present in humans, triggers the burning of extra calories.

THE BAD NEWS

-- Clean living may not be enough to ensure long life. A study of 300 French men and women more than 100 years old has shown that at least part of the reason for their longevity may be the presence of two genes. One is called apoe; get the wrong version and you may be subject to high cholesterol and Alzheimer's disease. Centenarians tend to have the right version. They are also more likely than average to have a particular version of the ace gene, which influences blood pressure.

-- Blood tests that purport to detect immune-system reactions to silicone leaked from breast implants are unreliable, say critics. The tests do detect antibodies, but not necessarily ones related to silicone.