Scientists Trace Loss of Hair Color

By Ven Griva

Copley News Service

Few things are as inevitable as gray hair, yet scientists have for decades searched in vain for the cause of this unwelcome sign of aging.

In a report posted Dec. 23 on the Web site of the journal Science, researchers from Dana-Farber Cancer Institute and Children’s Hospital Boston say that in a case of serendipity they have found the cellular cause of graying hair while investigating the origins of a potentially fatal cancer: malignant melanoma.

The scientists traced loss of hair color to the gradual dying of adult stem cells that form a reservoir that spawns a continuous supply of new pigment-manufacturing cells called melanocytes. It is melanocytes that give hair its youthful hues.

Not only do the non-specialized stem cells become depleted, they also progressively make errors and turn into fully committed pigment cells in the wrong place within hair follicles, which is useless for coloring hair.

The new findings solve a long-standing puzzle about the underlying mechanism of graying. Of more interest to the researchers, though, is the pattern of cellular signals that triggers the death of pigment stem cells. That’s because melanoma is dangerous for the opposite reason – melanocytes proliferate uncontrollably to form tumors and are hard to kill with treatment.

The researches offer no hope for the terminally gray, though.

“Preventing the graying of hair is not our goal,” emphasizes Dr. David E. Fisher, director of the Dana-Farber Program in Melanoma, and senior author of the Science paper. “Our goal is to prevent or treat melanoma, and to the extent this research is revealing the life cycles of melanocytes, which are the cells that become cancerous in melanoma, we would love to identify a signal that would make a melanoma cell stop growing.”

In 2004, the American Cancer Society expects about 55,100 people to be diagnosed with melanoma, the most serious form of skin cancer, with an estimated 7,910 deaths.

NEVER TOO LATE TO EXERCISE

Researchers at Johns Hopkins School of Medicine have found that for people age 55-75 a moderate supervised exercise regimen can significantly offset the potentially deadly mix of risk factors for heart disease and diabetes known as metabolic syndrome.

The findings raise the importance of physical exercise in treating men and women with the metabolic syndrome, a clustering of three or more risk factors that make it more likely for someone to develop heart disease, diabetes and stroke – including high blood pressure, elevated blood glucose levels, excess abdominal fat and abnormal cholesterol levels.

Published Dec. 30 in the American Journal of Preventive Medicine, the study is believed to be the first to focus on exercise in treating metabolic syndrome in the elderly.

To assess the benefits of exercise, the Johns Hopkins team studied 104 seniors for six months between July 1999 and Nov. 2003. All participants had no previous signs of cardiovascular disease beyond untreated, mild hypertension.

Half the participants were randomly assigned to a control group that received a booklet encouraging increased activity, such as walking, to promote good health. That half showed negligible improvement.

The other half participated for 60 minutes three times a week in a supervised series of exercises designed to work all major muscle groups, the heart and circulation. The regimen included aerobic exercises and weightlifting. For that half, aerobic fitness increased 16 percent and strength fitness increased 17 percent, thus reducing the risk of heart disease and diabetes.

Average weight loss in the exercising group was only 4 pounds because much of the loss of fat was offset by increased muscle mass. Abdominal fat, an important risk factor for metabolic syndrome, was reduced by 20 percent for those in the exercising group.

By the end of their six months, the 52 members of the exercising group had no new cases of metabolic syndrome and the condition had resolved in nine of them.

“A novel finding of our study was that the changes in disease risk factors with exercise training were more closely related to reductions in body fat, particularly abdominal fat, and increases in muscle tissue, rather than improvements in fitness, said lead study author Dr. Kerry Stewart, professor of medicine and director of clinical exercise physiology and heart health programs at The Johns Hopkins University School of Medicine and its Heart Institute.

Estimates of the prevalence of metabolic syndrome range from 25 percent to 40 percent of American adults age 40 and older.

E-mail Ven Griva at ven.griva@copleynews.com or write to P.O. Box 120190, San Diego, CA 92112.

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