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Purging Drugs Of Their Evil Twins


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PURGING DRUGS OF THEIR EVIL TWINS

PROMISING DRUGS MUST SOMETIMES BE SHELVED because they contain sinister elements that are mirror images of the beneficial ingredients. Many molecules come in two versions--chemically identical, but reversed in structure. Chemists dub them right-handed or left-handed and refer to them as chiral molecules. When thalidomide was marketed 40 years ago, a left-handed molecule provided relief from morning sickness. But its right-handed counterpart caused horrible birth defects.

Because chiral molecules behave the same in chemical reactions, separating them is tough. That may soon change. Isiah M. Warner, chairman of Louisiana State University's chemistry department, recently received $750,000 in federal grants to develop promising solutions he has pioneered.

One uses tiny balls of special surfactant molecules. While these attach to both chiral forms, either the right-handed or the left-handed version has a slightly stronger bond--and this can be exploited. Pass a current through the solution, and the weak-bond clumps move more rapidly toward an electrode, leaving behind the strong-bond clumps. Warner believes this process could be scaled up to purify bulk chemicals.EDITED BY OTIS PORTReturn to top

OPEN WIDE: YOUR DENTIST COULD HELP PREVENT STROKE

EACH YEAR, HALF A MILLION Americans suffer a stroke. For some, it's deadly. Others are left with disabilities such as partial paralysis in a limb, or a speech impediment. Usually, there are no warning signs. But dentists may soon fill that void and become a first line of defense against strokes.

Researchers at the University at Buffalo have found that routine dental X-rays seem to be an effective tool for spotting potentially dangerous calcium buildups in the carotid arteries. These arteries are near both ends of the jawbone and supply the brain with blood. Arterial calcium deposits that choke off blood to the brain are a major cause of stroke.

Dr. Laurie C. Carter, a radiologist at the university's School of Dental Medicine, led the team in examining the X-rays of 2,752 new clinical patients. About 5% of them had calcification and were advised to visit their doctors. Now the team is gearing up to corroborate the research. For example, one study involves taking dental X-rays of recent stroke victims to see how many have visible calcium deposits that might have warned they were at risk.EDITED BY OTIS PORTReturn to top

EASY-TO-SWALLOW NEWS FOR DIABETICS

A NUMBER OF DRUGS, SUCH as insulin and immunoglobulins, are too fragile to survive digestion or too big to pass through the intestinal wall into the bloodstream. So millions of diabetics and other patients must endure daily injections. But researchers are racing to turn these injectable drugs into easy-to-swallow pills.

One approach is to coat the drug with a biodegradable polymer. The coated drug passes through the stomach, then sticks to the walls of the small intestine. There the polymer breaks down, and the drug can enter the blood. In animal experiments reported in the Mar. 27 issue of Nature, a team led by Edith Mathiowitz of Brown University showed this method can work for insulin.

Even more impressive results come from borrowing one of nature's tricks. While developing a cholera vaccine in 1991, pediatrician Alessio Fasano of the University of Maryland discovered a previously unknown bacterial protein that can open gaps in the small intestine's wall. The cholera bug uses this protein, dubbed Zot, to tap the body for fluids. But Fasano realized the openings could also be portals for moving big molecules into the blood. "We found the key for a gate already there," he notes.

In experiments with rats, Fasano has shown that insulin given orally with Zot does ends up in the blood. Next, the method will be tested in monkeys and people. "If this technique brings the possibility of giving insulin orally, it will be a major breakthrough," enthuses Fasano. He's already talking to several drug companies that want to commercialize the approach.By John Carey EDITED BY OTIS PORTReturn to top


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