1. From The Methodist Hospital Research Institute & The Methodist DeBakey Heart Center (J.F.G., E.J.L., D.G.S., A.E.R., G.L.K.), Houston, Tex; Department of Mathematics (D.W.B.), University of Houston, Houston, Tex; Baylor College of Medicine (H.K.W.), Houston, Tex; The Corbic Research Foundation-HMUA (C.L.A.), Envigado, Colombia; Instituto de Ciencias de la Salud (A.B.), Medellin, Colombia; Department of Pathology (R.B.), The Methodist Hospital, Houston, Tex.