Developments to Watch
IN SEATTLE, IT'S RAINING RESEARCH
Surprising findings on AIDS, cancer, woodlands, and birds
More than 5,000 scientists and reporters convened under clear skies in Seattle last week for the annual meeting of the American Association for the Advancement of Science. One headliner: Microsoft Corp. Chairman Bill Gates, whose prophecies were interrupted when his software flopped. Researchers discussed advances in such fields as AIDS, genetics, and birds' migration patterns. Senior Correspondent John Carey and Senior Editor Paul Raeburn report some of the highlights.Return to top
AN AIDS WEAPON FROM A LAB MISHAP
IT WAS TWO YEARS AGO WHEN a researcher at the University of Maryland's Institute of Human Virology in Baltimore thought he had ruined an important experiment. He was injecting mice with cells of Kaposi's sarcoma, an AIDS-related cancer, to see if any of the mice had qualities that could protect them against the tumors. The mistake came when he put males and females in the same cage. The females became pregnant, which changed their hormonal balance and should have spoiled the test.
Instead, something remarkable happened: The pregnant females turned out to be essentially immune to Kaposi's sarcoma. Studies uncovered a class of molecules that shield against the AIDS virus without apparent side effects. The active chemicals, not yet fully identified, are called HCG associated factors, or HAFs. (HCG is a hormone produced early in pregnancy in mice and humans.) Dr. Robert Gallo, director of the Institute of Human Virology, says his staff is racing to identify exactly which HAFs are responsible for the protection.
Not only do HAFs seem to be safe, but they promote the growth of bone marrow, Gallo reports. A research collaborator has demonstrated that, in a handful of cases studied so far, HAFs kill Kaposi's sarcoma cells in human subjects. "These are things we want to bring to clinical use as soon as possible," Gallo says.Return to top
HITTING CANCER WHERE IT HURTS
SINCE THE 1970s, SCIENTISTS have dreamed of zapping cancer with a biological magic bullet. They envisioned an antibody that homes in only on cancer cells to deliver a powerful toxin just to those cells.
The dream may finally come true. Dr. David A. Scheinberg of New York's Memorial Sloan-Kettering Cancer Center announced the first clinical trial using an antibody linked to a source of cancer-zapping radiation. The initial quarry: leukemia.
It took years to engineer the antibodies and design a way to attach the right cancer-killing substances. But Protein Design Labs Inc. in Mountain View, Calif., has cooked up an antibody that targets the CD-33 receptor found on leukemia cells. To the antibody, Scheinberg's team attaches bismuth-213, an element that emits alpha-particle radiation, but only for a short time; its so-called half-life is 47 minutes. In preliminary clinical tests, the combination swarmed over leukemia cells without apparent side effects. If this approach snuffs out leukemia, Scheinberg hopes to adapt it for mopping up cancer cells often left in the body after cancer surgery.Return to top
FORESTS: WORTH MORE ALIVE?
THE TOWERING DOUGLAS FIRS and other venerable trees that ring Seattle have been the focus of fierce environmental battles. The question comes down to this: Are the standing trees worth more than the lumber they could yield? Walter V. Reid of the World Resources Institute in Washington argues that natural ecosystems such as the Pacific Northwest forests are the source of products and services that are worth hundreds of millions of dollars, or far more than their lumber value.
The Northwest forests were the source of Taxol, an important new cancer drug extracted from the Pacific yew. Indeed, 57% of the medicines used in the U.S. come from nature's products. And their potential value is rising as it becomes easier to find them. It now costs only $150,000 to screen 10,000 natural extracts for possible pharmaceutical use, Reid says. Stepped-up prospecting is already starting to pay off: A substance called michellamine B was recently extracted from a vine in Cameroon. Laboratory studies suggest it could be effective against AIDS.Return to top