JUST for the record, vampire bats don't suck. They lap.
Under the cover of darkness, the mouse-sized \o7Desmodus rotundus\f7 flies out from rocky caves to find a sleeping horse or cow. Its razor-sharp incisors carve out a tidy crater of flesh, no bigger than a Halloween M&M, usually without waking its prey.
Then, perched over the welling wound, the vampire bat laps up about a tablespoon of blood -- its sole source of nourishment -- with a delicate, bright-pink tongue.
Normally, wounds like these would start to heal within minutes. But dinnertime for a vampire bat lasts as long as half an hour. Its saliva contains a special enzyme that immediately liquefies blood clots, keeping the vampire bat's meal smooth and fresh.
The same problem facing vampire bats -- the need to keep blood vessels clot-free -- also faces cardiovascular researchers. Now some of them are hoping the enzyme that allows vampire bats to avoid feeding on mouthfuls of coagulated blood might also help prevent brain damage in stroke victims.
Since last year, clinical trials have been underway to test the effectiveness of a genetically engineered, bat-saliva enzyme in a new clot-busting drug to be used for emergency treatment of ischemic stroke, in which blood supply to the brain is cut off. If approved, the drug would allow doctors to treat patients up to nine hours after symptoms begin, extending the current three-hour limit for stroke medication.
Earlier studies in humans and animals have found the drug, called desmoteplase, to be safe and accompanied by fewer side effects than existing treatments. The hope is that desmoteplase acts to dissolve \o7only\f7 the clotted area blocking blood flow to the brain and causing stroke -- thus leaving fragile blood vessels in the brain intact.
Although researchers are still hopeful about desmoteplase, more information is needed about its safety. On Wednesday, the study's coordinators announced that they were temporarily halting enrollment of new patients to allow time for more patient safety data to be analyzed.
In 2004, the Food and Drug Administration granted desmoteplase's developers, Paion in Germany and Forest Laboratories Inc. in New York, a fast-track application. These applications aim to speed the development process of products addressing unmet medical needs.
