Developments to Watch
EXPANDING ON MOTHER NATURE'S PHARMACY
A SURPRISING NUMBER OF blockbuster drugs have sprung from one diverse group of naturally occurring molecules called polyketides, which are produced by soil bacteria and fungi. The list includes the antibiotic erythromycin, a cholesterol-lowering agent called Mevacor, and FK506, a powerful immunosuppressant used on transplant patients.
Scientists would like to custom design more of these molecules, but in most cases, the molecules have proven too complex to synthesize. Now, a team of biochemists and organic chemists at Stanford, Brown, and the University of Wisconsin claims to have solved the problem, using a combination of gene splicing and chemistry. The first results, reported in the latest issue of Science, are several new variants of erythromycin.
According to Stanford team leader Chaitan Khosla, the researchers interrupted the sequence whereby genes in streptomyces bacteria produce the antibiotic. They then added man-made chemicals to the mutated cells. These are incorporated into the new versions of erythromycin. Khosla and his colleagues have started Kosan Biosciences Inc. in Burlingame, Calif., where they hope to design thousands of polyketides targeted at heart disease, cancer, and drug resistant bugs.EDITED BY CATHERINE ARNST Neil GrossReturn to top
AN END RUN AROUND CHEMO'S SIDE EFFECTS?
VETERINARIANS AT COLORADO State University have discovered that a method used to treat bone cancer in dogs shows promise in humans. The key is biodegradable spongy materials called biopolymers that are loaded with cancer-killing drugs and surgically inserted next to a tumor. There they release a constant dose of the chemical directly to the cancer cells, a delivery method less toxic and less expensive than chemotherapy delivered by injections.
Colorado State veterinarians started using the polymers to treat dogs 10 years ago. The researchers figured the same treatment should work with humans, says William Dernell, assistant professor of surgical oncology at the veterinary center. A recently completed study of 42 mice with breast cancer found that the implanted polymers eliminated all regrowth of the cancer. But breast cancer recurred in half the mice that received chemotherapy by injection. "This opens a wide range of possibilities in developing new drugs to fight cancer and heal the body from the inside," says Dernell.
The research team is now undertaking a study of 180 mice with breast cancer, but Dernell predicts it will be at least four years before the polymers can be tested on humans.EDITED BY CATHERINE ARNSTReturn to top
A VOICEBOX TO CHILL YOUR ICEBOX
NOT ALL THE COOL VIBES COME FROM RECORDING STUDIOS these days. A research team at Purdue University in West Lafayette, Ind., is testing a prototype cooling device that uses sound waves rather than Freon. The concept is called thermoacoustic refrigeration.
The cooling device consists of a metal tube with a loudspeaker on one end that produces sound waves. Each wave creates pressure fluctuations that result in temperature changes: the higher the pressure, the higher the temperature. In the middle of the tube, layers of ceramics draw the heat out of the sound waves before they hit the opposite end. The remaining "cold sound" cools the tube, which in turn could cool water or some other fluid that could then circulate through a refrigerator or air conditioning system.
Thermoacoustic cooling has been around for more than 10 years, but earlier systems used much more energy than conventional fridges. Luc G. Mongeau, assistant professor of mechanical engineering at Purdue, says his team's prototype was built to be as efficient as possible. If the test pans out, the design will compete with conventional systems, he says.EDITED BY CATHERINE ARNST Elizabeth VeomettReturn to top