1. From the Neuroprotection Research Laboratory (E.H.L.), Departments of Radiology and Neurology, Massachusetts General Hospital, and Program in Neuroscience, Harvard Medical School, Charlestown, Mass; Department of Neurology (J.P.B.), University of Cincinnati, Cincinnati, Ohio; and Neurovascular Regulation and Stroke Laboratory (M.A.M.), Departments of Radiology and Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Charlestown, Mass.