Capsules

ATTACKING HEART ATTACKS

A single aspirin a day can help keep heart attacks away for hundreds of thousands of Americans, according to a striking new report from the Veterans Administration. The study involved 1,266 male patients suffering from unstable angina, an extremely painful condition that is often a harbinger of heart attacks. About half the men (625) took one dose of aspirin daily in the form of an Alka-Seltzer solution (used because it is less upsetting to the stomach than plain aspirin). The other patients were given a fizzy placebo.

At the end of twelve weeks, the rate of both heart attack and mortality was 51 % lower among aspirin users than among the group taking placebos. Though aspirin is thought to interfere with potentially dangerous clotting of blood, earlier tests showed it to be of limited help to patients who have already had a heart attack. The new data, however, clearly demonstrate that small doses are very effective in preventing heart attacks in people who have had the warning signs of unstable angina.

TWO STEPS TO CANCER

Three years ago, researchers announced the discovery of human genes that were capable of turning ordinary cells into malignant ones. The news met with some skepticism. Experts asked how a single gene could cause such a dramatic change. Why does cancer take years or even decades to develop if it is caused by such a simple and direct process? In last week's issue of the British journal Nature, three research teams answered those questions by setting forth a new model for understanding the role of oncogenes in cancer.

Each group found that it does in fact take more than a single cancer gene to produce cancer in normal cells. Teams at M.i.T. and Cold Spring Harbor Laboratory on Long Island, N.Y., reported that they could induce cancer in normal rat cells only by inserting at least two types of oncogenes into the cells. "A single oncogene produced some changes, but not cancer," explained Molecular Biologist Robert Weinberg of M.I.T. "It took two genes acting cooperatively to produce a tumor. In other cases, it might take three or more."

A British team confirmed the multi-step cancer scenario by showing that a particular oncogene caused a tumor in hamster cells only if they had first been exposed to a carcinogenic chemical. The chemical alone and the oncogene alone did not cause cancer; both were necessary. While the discovery has no immediate implication for treatment of cancer, it helps explain why the disease develops slowly and why its incidence rises with age. "Even if one part of the process occurs," says Weinberg, "you might not have the second step for another 20 years." This file is automatically generated by a robot program, so viewer discretion is required.