1. From the Departments of Neurology (M.F., A.M.), Preventive Medicine (A.P.-H.), and Pathology (M.C.), University of Southern California School of Medicine, Los Angeles, Calif; Wake Forest School of Medicine (J.F.T.), Winston-Salem, NC; The John P. Robarts Research Institute (H.J.M.B.), London, Ontario, Canada; and the Department of Clinical Neuroscience (J.N.), St Georges Hospital Medical School, London, UK.