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Asthma culprit cloned.

Asthma culprit cloned

It starts with some wheezing, a hoarse, dry cough and a growing sensation of pressure that leaves victims panicked and gasping for breath. War in the Middle East notwithstanding, this is not a poison gas attack. These symptoms represent common occurrences for the more than 8 million Americans with asthma.

Despite decades of work, scientists have yet to design the perfect asthma drug -- one that specifically targets the potent biochemical mediators of this immune overreaction. But new research led by a Japanese physiological chemist may speed the development of such a drug.

Takao Shimizu at the University of Tokyo, with colleagues there and at the Protein Engineering Research Institute in Osaka, has cloned the cell-surface receptor for a blood compound called platelet-activating factor (PAF) -- one of the body's most potent alarm chemicals and the one responsible for much of the biochemical mayhem underlying asthma attacks and other inflammatory reactions.

When released from blood cells in response to an allergic reaction or toxic exposure, PAF triggers circulating platelets to release substances that promote bronchial spasms and leakage of fluid into the lungs. The newfound ability to mass-produce PAF receptors should help medicinal chemists design drugs that can calm the oversensitive receptors, the researchers assert in the Jan. 24 NATURE.

"It's very good work, an important development," says Donald J. Hanahan, a PAF biochemist at the University of Texas Health Sciences Center in San Antonio. He notes that PAF is made of fat rather than protein, and says the new work seems to mark the first cloning of a receptor for a fat-mediated cellular signal. As such, Hanahan says, the new research may also help explain how prostaglandins and leukotrienes -- extremely potent, fat-based mediators of pain and inflammation -- perform their biological duties.
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Title Annotation:platelet-activating factor
Publication:Science News
Date:Jan 26, 1991
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