1. From the Department of Laboratory Medicine (T.W.K.), University of California, San Francisco; the Department of Internal Medicine (K.A.G., A.K.B.), Loyola University & Hines VA Hospital, Maywood, Ill; the Department of Anatomy and Cell Biology (R.L.D.), University of Iowa, Iowa City; and the Department of Physiology and Biophysics (J.E.H.), University of Mississippi, Jackson.