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Genetic cause of narcolepsy pinpointed, scientists say

Scientists believe they have discovered a genetic flaw deep within the brain that causes narcolepsy, the bizarre disorder that makes people fall asleep without warning.

An estimated 135,000 Americans have narcolepsy, and until now its cause has been a mystery. Experts say the latest discovery should offer solid clues for finding better treatments.

Two groups of scientists, working independently, found that narcoleptics' overwhelming urge to fall asleep may result from a glitch in signals sent between cells in the hypothalamus, a part of the brain that regulates appetite and other basic drives.

The genetic error was documented only in dogs and mice. But researchers say they are confident that a similar defect will be shown to be at fault in some human cases, although the origins of the disease are almost certainly far more complex in people than in animals.

"Clearly, these two papers will revolutionize the field of sleep research," predicted Juliette Faraco of Stanford University, a geneticist who co-wrote one of the studies.

The Stanford research, directed by Dr. Emmanuel Mignot, is being published in today's issue of the journal Cell. Another study reaching similar conclusions was conducted by Dr. Masashi Yanagisawa of the University of Texas Southwestern Medical Center in Dallas. It will be published in Cell on Aug. 20.

Skin peeling after sunburn

called shield against cancer

WASHINGTON _ Sunburns may be painful, but new medical research shows that the skin peeling after a burn is one way the body protects against skin cancer.

In mouse studies at the University of Texas M.D. Anderson Cancer Center, researchers found that sunburned skin makes a protein that kills any cells with mutations that might otherwise lead to cancer. The damaged cells are then sloughed off.

"Our finding is the first to identify a protein that is a natural defense against skin cancer," said Laurie Owen-Schaub, senior author of a study to published today in the journal Science.

Skin cancer is the most common form of cancer. About 1-million cases of basal cell and squamous cell cancer are diagnosed annually in the United States. The most serious form of skin cancer, melanoma, is diagnosed in about 44,200 Americans annually. Skin cancer can be easily treated if detected early, but the disease kills about 9,200 Americans annually.

Exposure to ultraviolet radiation from the sun is thought to be the most common cause of the genetic changes linked to skin cancer. Studies have shown that UV radiation can disable certain genes that normally keep cancer in check.

Owen-Schaub said her team found that a protein called "fas" is the key to protection against sun-linked skin cancer. Fas helps to eliminate those cells that are a cancer threat because they have been genetically damaged by the sun. In effect, fas directs a suicide process that causes mutated cells to kill themselves.

If a cell has only a small amount of damage to its DNA, then it will just repair the damage and continue to function normally. But when there is a great deal of damage, such as happens with a sunburn, there is only one solution.

"With an excessive amount of DNA damage, the cell will just eliminate itself because the repair could miss some of the mutations that could be critical in skin cancer," she said.

Fish oil capsules greatly help

heart attack victims, study says

LONDON _ People who have suffered heart attacks can reduce their risk of heart-related death by 30 percent by taking a fish oil capsule every day, a new study suggests.

"People who are looking for more than circumstantial evidence of a benefit of fish oil will find reassurance from this," Dr. Morris Brown, a Cambridge University researcher, said of the Italian study _ the most rigorous to date investigating the oil's potential heart-healthy properties.

The study, published in this week's issue of the Lancet, a British medical journal, also looked at vitamin E pills. But, unlike other studies, it did not find they offer heart attack survivors protection from further heart problems.

"For both of these dietary components, there is a wealth of circumstantial evidence for benefit," wrote Brown, who was not connected with the study.

Previously, both fish oil and vitamin E were found to offer benefits in studies of past eating habits. However, in studies where the nutrients were introduced into the diet, the results have been conflicting.

The Italian study involved 11,324 men and women who had suffered a heart attack no more than three months before.