Mali's Unabated Drought Drains Life From Villages

Although the Ethiopian drought and famine have abated in recent months, images obtained by the Landsat 5 satellite show that severe drought continues to grip much of the African Sahel, the transition zone between the Sahara and the forests to the south, according to Patricia A. Jacobberger, a geologist at the National Air and Space Museum.

Pictures from the satellite show that 75 percent of the lakes, ponds and swamps mapped as permanent bodies of water in the western African nation of Mali in the 1950s are now dry. Around many villages that once were set amid lush vegetation, the pictures now show a wide ring of bare, dry soil.

Jacobberger, who trekked through many parts of Mali last year to compare reality on the ground with the pictures from space, found most of the villages abandoned. She said the drought that began in 1965 is still draining life from the land and the people. Although rainfall improved in 1976, 1978 and 1979, leading many to conclude that the drought was over, the rains failed again in 1980 and have been poor since.

"The area is at a turning point," she said of the once verdant, 3,400-square-mile flood plain of the Niger River. "A lot of channels formerly carried water year around and have now been abandoned. If the rains do not increase substantially, there will be a fundamental change in the morphology of the river, and it would mean the death of the flood plain on which so many of Mali's 7 million people depend." Anticockroach Fungus Discovered

Michael Rust had become increasingly distraught since 1980 when his cockroaches started dying inexplicably.

In 1984, after more than a million captive roaches died in Rust's lab -- he is an entomologist specializing in the species -- he discovered why and, in the process, may have stumbled upon one of the most powerful roach killers ever identified.

Edwin Archbold, a colleague of Rust's at the University of California at Riverside, found the cause. It was a fungus growing in the lab. The roaches ate it and the fungus colonized the insects' insides, eventually killing them.

Rust, Archbold and a third colleague, Gary Reirson, have developed a way to grow the fungus under controlled conditions and proven its potency. It kills German cockroaches, the small, brown species most common in homes and restaurants outside the deep South, but does not seem to affect larger roaches.

The researchers, who published their findings in the February issue of Environmental Entomology, say it may be possible to turn the fungus into a commercial product in a few years. There is no evidence yet that the fungus is harmful to human beings or pets.

One major question is whether the insects will eventually evolve resistance to the fungus as they have to most other roach poisons. Rubbing Out the Cat Flea

Cat fleas have developed resistance to the insecticides usually used to control them, researchers at the Agricultural Research Service have found.

The fleas thus join a long list of insect pests that have evolved resistance to many of the major chemicals once fatal to them.

There is, however, hope for the itchy cat and cat owner.

Richard S. Patterson of the service's Insects Affecting Man and Animals Research Laboratory in Gainesville, Fla., has developed synthetic versions of the hormones that fleas produce to regulate their growth. The insects die when exposed to the chemicals in ways that disrupt their maturation. One is already commercially available. Impotence Linked to Blocked Blood Flow

Chronic impotence, a problem that afflicts an estimated 10 percent of men, is most often caused by disorders of blood flow to the penis, according to a University of California, San Francisco urologist.

His finding challenges the longstanding belief that most impotence has a purely psychological cause.

The researcher, Dr. Tom F. Lue, told a meeting of the American Urological Association last week that his study of more than 650 men suffering from impotence indicates that in 80 percent, the cause is physical, not mental. He also reported preliminary results on a treatment that helped 60 of 100 patients it was tried on.

Lue's findings were based on his studies of the mechanism of penile erection, which is caused by an increase in blood pressure inside the penis. When the penis is flaccid, special muscles called sinusoids are contracted in a way that constricts arteries supplying blood to the penis. Only enough blood flows to sustain the tissues.

In a normal erection, the sinusoid muscles relax, allowing more blood to enter the penis than can exit through veins. A dense network of blood vessels swells, producing erection.

Lue found that by injecting a muscle relaxant drug called papaverine directly into the penis, some degree of erection usually resulted, even in otherwise impotent men. Ultrasound imagery of the blood vessels in drug-induced erections showed Lue that most impotent men had abnormalities of blood vessels in the penis, either arteries that did not expand enough or veins that were too large, allowing the increased blood flow to drain as fast as it entered.

The testing revealed that the same drug could also treat the disorder. In some cases, Lue said, periodic artificial erections helped condition penile muscles so that they functioned better during normal sex.

Even the chiefly psychological cases improved, Lue said, when the injections showed the men they were physically capable of erection and increased their confidence.