1. From the Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology (F.S.M., G.R.N., O.H.I.M., M.B., L.V., M.J.M., P.S., A.J.W.), and the School of Pathology (J.P.), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.