IN BRIEF (Page 19)

AGD the new measure of fertility

When it comes to male fertility, it turns out that size does matter.

The dimension in question is not penis or testicle size, but a measurement known as anogenital distance, or AGD.

Men whose AGD is shorter than the median length - around 52 mm - have seven times the chance of being sub-fertile as those with a longer AGD, according to a study published in the journal Environmental Health Perspectives.

That distance, measured from the anus to the underside of the scrotum, is linked to male fertility, including semen volume and sperm count, the study found. The shorter the AGD, the more likely a man is to have a low sperm count.

This offers the prospect of a relatively simple screening test for men, says study co-author Shanna Swan of the University of Rochester Medical Center.

"It's non-invasive and anybody can do it, and it's not sensitive to the kinds of things that sperm count is sensitive to, like stress or whether you have a cold or whether it's hot outside," Swan says.

"If somebody's got a short AGD, particularly if they have problems conceiving, I would say get to the infertility doctor, because the chances are good that something is wrong."

Blood test for Down's Syndrome

Pregnant women may soon be able to have a blood test to predict whether their babies are likely to have Down's Syndrome instead of undergoing risky, invasive tests, scientists said on Sunday.

In a study in the Nature Medicine journal researchers from Cyprus said a trial on 40 pregnancies using the test, which involves analyzing the woman's blood to detect DNA differences between the mother and the fetus, showed it accurately predicted which fetuses were at risk of developing the syndrome.

Philippos Patsalis, medical director of the Cyprus Institute of Neurology and Genetics, who led the study, says the results were "very exciting" and the test now needed to be put to trial in a larger study of about 1,000 pregnancies, but could lead to changes in clinical practice within two years.

"We believe we can modify this test and make it much easier and simple ... (and then) we can have something ready to be introduced into the clinic," he says.

Down's Syndrome is the most common genetic cause of mental retardation, occurring in 1 out of 700 live births worldwide.

Balanced diet better than supplements

Dietary supplements are generally unnecessary and less effective than eating a balanced diet, according to Michael Krawinkel, a professor at Giessen University's Institute for Nutritional Sciences in Germany.

Writing in a German nutrition magazine, Krawinkel notes that someone whose daily intake of vitamins and minerals did not always meet the recommended levels usually averaged sufficient amounts over the course of a week.

Claims of a deficiency of selenium, magnesium, or vitamins D, C or E in many people are often false, he says.

For some groups of people, however, dietary supplements are advisable, Krawinkel points out.

Expectant mothers should take folic acid in the first weeks of pregnancy, infants should be given vitamins K and D as well as fluorine, and people aged 65 and older would do well to take vitamin D regularly.

Visual nerves remain active in the blind

Even people blind from birth have active visual nerves in the brain that, rather than processing optic information, may enhance their sense of touch and support fast reading of Braille, according to researchers from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany.

A research team headed by neurophysicist Robert Trampel discovered that the Stripe of Gennari, a bundle of nerve fibers approximately 0.3 mm thick that traverses the gray matter of the primary visual cortex as a distinct white line, develops as fully in congenitally blind people as it does in sighted ones.

Why the Stripe of Gennari develops and what its function is has not previously been studied in detail, Trampel notes. "A connection with sight was naturally assumed," he says. "As it turns out, however, this can't be the sole function."

Using magnetic resonance imaging, the researchers examined the brains of both blind and sighted people. In the blind people, the area around the Stripe of Gennari, in the backmost part of the cerebrum, showed increased activity when they were reading Braille.

Reuters-DPA

(China Daily 03/09/2011 page19)