Vitamin relative may aid stroke repair. (Biomedicine).

Vitamin C can't pass through the so-called blood-brain barrier to gain entry into the brain, but its precursor, dehydroascorbic acid (DHA), can. Thanks to this trait, DHA might help stroke patients retain the use of endangered parts of their brains, a new study finds.

When a clot shuts off blood flow to part of the brain, patients sometimes receive powerful clot-busting drugs to reopen the blocked vessel. In other people, blood finds alternate routes to threatened areas. This resurgence of blood can't save brain cells that are dead, but it can salvage nearby tissue that faces a dwindling blood supply.

Meanwhile, blood flow shut-off and restoration both unleash free radicals--highly reactive molecules that disrupt cells and complicate the capability of the smallest blood vessels, called capillaries, to nourish tissue and keep it alive.

Antioxidants such as DHA and vitamin C neutralize free radicals. To assess their value in limiting stroke damage, David W. Golde of Memorial Sloan-Kettering Cancer Center in New York, and his colleagues experimented with mice. The researchers modeled strokes in people by shutting off blood flow to parts of the animals' brains and then restoring it in some mice.

The mice getting DHA infusions as much as 3 hours after an induced stroke preserved function in more of the brain than did mice getting vitamin C or an inert substance, the scientists report in the Sept. 25 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES. Further testing is needed, but the work suggests that DHA might limit the brain area damaged by stroke, Golde says. --N.S.