MS: cooling it chemically.

People with multiple sclerosis tend to suffer fewer symptoms of the nerve-degenerating disease in cold weather. Patients who can walk often lose that ability when they have a fewer. To exploit this temperature dependence, Floyd Davis and colleagues at Rush Medical College in Chicago have been working with 4-aminopyridine, a chemical that mimics the effect of cold on nerves. The drug looks promising but much more work needs to be done before it can be considered for use, Davis says.

Cold slows down thee nerve impulse, which is electrically conducted, resulting in an increased current. That can power the impulse through the degenerated part of the nerve, Davis says. The drug slows down the nerve impulse by blocking the flow of potassium ions, which conduct the current.

In a study of 12 patients with particularly heat-sensitive MS, being presented this month in Chicago at the American Neurological Association meeting, Davis and his colleagues found that seven of the 12 had a significant improvement in vision, and five showed a greater use of their arms and legs. At the moment, 4-aminopyridine has to be administered intravenously, and its effects wear off within a few hours.

"It offers hope for a way of treating the disease, but it won't reverse the process," Davis notes.

Byron Waksman, director of research for the National Multiple Sclerosis Society, which funded the work, says, "It's not anything that can be used as a treatment, but it shows the approach has merit."