1. Laboratory of Neurochemistry, Neurology Service, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusettes, U.S.A.
2. Stroke and Neurovascular Regulation, Neurology Service, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusettes, U.S.A.
3. Cardiovascular Research Center, Neurology Service, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusettes, U.S.A.