1. From the Stroke Prevention Research Unit, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK, and the University of Oxford, Oxford, UK (S.T.P., S.J.V.W, F.C.C., J.M., Z.M., P.M.R.); and National Institute of Health Research Biomedical Research Centre, Oxford, UK (S.T.P.).