Saturday, March 12, 2011

Snake Venom, a Cornucopia of Medicines

I take ramipril for high blood pressure. I didn't realize it was developed from snake venom. From an article by Carl Zimmer in Discover magazine:
As a result of this evolution, scientists have lots of different venoms to explore to see if they’re useful in medicine. Millions of people rely on venom to keep their blood pressure in check, for example. ACE inhibitors were isolated from Brazilian pitvipers, which use the molecule to make their prey black out from a drop in blood pressure. Saw-scaled vipers make blood-thinning venoms, which have been turned into an anticoagulant drug called tirobifan. A number of venom drugs are now in the pipeline to treat cancer, bacterial infections, and other ailments.
And here's a bit about how snake venom helped decode the disease myasthenia gravis:
Just as Changeux had hoped, the krait venom latched onto one receptor in particular. Using the venom as their guide, the scientists could purify a big enough supply of the receptors to figure out its structure–the first time such a feat had ever been accomplished for a receptor on a neuron.
Soon, this discovery bore medical fruit, by allowing scientists to understand a disease called myasthenia gravis. Myasthenia gravis slowly weakens the muscles, making it hard to swallow, talk, and keep one’s eyelids open. In 1973 scientists at Johns Hopkins applied radioactive ╬▒-bungarotoxin to muscle tissue from people with myasthenia gravis. The radioactive venom latched onto their acetylcholine receptors, allowing the scientists to count them up. They discovered that people with the disease had fewer receptors than normal.
Researchers wondered if the immune system was mistakenly attacking the receptors and destroying them. If that were true, then you’d expect people with myasthenia gravis to have antibodies to the receptors. In 1976, scientists from the Salk Institute mixed together radioactive ╬▒bungarotoxin and acetylcholine detectors and then added them to a serum taken from people with myasthenia gravis. Just as the researchers had predicted, the serum was loaded with antibodies that attacked the receptors.
Here's a video from the article:

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