Some day it may be possible to detect problems in a person's biological clock by testing his or her skin cells, researchers report.

The genes that regulate the master biological clock in the brain also regulate clocks in other tissue, according to results of a study in mice.

The body's internal clock, or circadian rhythm, controls when we sleep and wake and plays a role in other biological processes as well, such as hormone production and blood pressure.

The main circadian clock is in the brain, but so-called peripheral clocks are located in other tissues, including the skin. Photoreceptors in the eyes help regulate the circadian clock in the brain, which sends signals to synchronize the peripheral clocks.

To see whether peripheral clocks work the same way as the master clock, a team led by Dr Hitoshi Okamura at Kobe University in Japan studied the clocks in skin fibroblasts (connective tissue) taken from mice.

The clocks in the peripheral tissue appear to function just as the brain's clock does, the researchers reported in the April 13 issue of the journal Science. The same set of genes interacts in the same way in both types of clocks, according to the report.

Assuming that peripheral clocks work similarly in humans, testing skin fibroblasts eventually could make it possible to detect defects in clock-related genes in people whose circadian clocks are out of whack, Okamura's team concludes.

"On the basis of our work with the mouse cell lines, we expect that it will be possible to determine whether someone has a fast or slow-ticking biological clock," Okamura said.

"This may help to unequivocally diagnose circadian disorders, which in turn may facilitate treatment."

'Biological Clock' Study

Children fathered by older men run a much higher risk of developing schizophrenia, researchers said last week in a finding that provides strong evidence that men, like women, have a "biological clock" when it comes to having children.

The study blows a gaping hole in the commonly held belief that while older women run a higher risk of having babies with birth defects, men face no such risk when fathering children even at an advanced age.

A child's risk of developing the devastating mental illness rises dramatically and steadily as the age of the father increases, according to researchers at Columbia University College of Physicians and Surgeons, New York University School of Medicine and Israel's Ministry of Health.

The researchers reviewed the records of 87,907 people born in Jerusalem from 1964 and 1976. They found that men between the ages of 45 and 49 were twice as likely as those under 25 to have children who develop schizophrenia.

Men 50 or older ran three times the risk of the fathers under 25.

The study said 26.6 percent of the schizophrenia cases could be attributed to the father's age, while the age of the mother appeared to play no role.

Paternal age was responsible for two thirds of the cases when the father was over 50.

Columbia University's Dr Dolores Malaspina, who led the study, said the findings augment a growing body of evidence of an increased likelihood of health problems for children of older men.

"This is the first psychiatric disease that's been linked to advancing paternal age," she said in an interview.

(Xinhua 04/17/2001)