Medical Leeches'

Sale Approved

The government has lent its seal of approval to marketing an age-old medical device -- leeches.

The Food and Drug Administration said yesterday that Ricarimpex SAS, a French firm, is the first company to request and receive clearance to market the bloodsucking aquatic animals as medical devices.

Leeches are already widely used in American hospitals, and companies that raised and sold them here before 1976 were allowed to continue doing so. But a law passed that year on medical devices required newcomers to the field to seek approval.

The FDA reports that leeches can help heal skin grafts by removing blood pooled under the graft and restore blood circulation in blocked veins by removing pooled blood.

Indeed the use of leeches to draw blood goes back thousands of years. The FDA noted that today they are used in medicine throughout the world as tools in skin grafts and reattachment surgery.

Medicinal leeches -- Hirudo medicinalis -- normally make their home in fresh water.

Bird Flu's Threat

To Mammals Grows

A strain of bird flu that scientists fear could lead to a worldwide pandemic in humans is becoming more infectious to mammals.

Millions of chickens and other fowl have been slaughtered in Asia -- and thousands more in the United States and elsewhere -- to stem outbreaks of avian flu in recent years. Scientists say it is only a matter of time before the virus adapts to spread among humans.

The flu already passed from birds to humans in Hong Kong in 1997, killing six of 18 infected people. Human cases have since been reported in Vietnam and Thailand.

Now China-based researchers studying the H5N1 flu strain report that over the years it is changing to become more dangerous to mammals. Their research, based on tests in mice, was reported by a team led by Hualan Chen of the Animal Influenza Laboratory of the Chinese Ministry of Agriculture in yesterday's issue of the Proceedings of the National Academy of Sciences.

The researchers tested the effect of the viruses in mice and found that the samples collected in 1999-2000 were less dangerous than those from 2001-2002.

Warmer Nights

Lower Rice Yields

Global warming could mean bad news for one of the world's most important crops: rice.

Higher nighttime temperatures were associated with significant declines in crop yield at the International Rice Research Institute Farm in the Philippines, said a report in yesterday's issue of the Proceedings of the National Academy of Sciences. An average daily temperature increase of 1.8 degrees Fahrenheit resulted in a 10 percent reduction in the rice crop, according to the researchers.

Increasing temperatures are thought to be a result of heat-trapped "greenhouse gases" emitted by human activity. Scientists have argued over the potential effects of climate change on crops, largely basing their contentions on laboratory tests and computer models of climate and crop yield.

This new study was a direct measurement of yields under field conditions using practices that good farmers would employ, said lead researcher Kenneth G. Cassman of the University of Nebraska.

Cassman and colleagues studied 12 years of rice yields at the farm, along with weather data, to reach their conclusions.

-- From News Services