1. From the Department of Laboratory Medicine and Pathology (B.T.S., M.Y.T.), University of Minnesota, Minneapolis
2. Department of Medicine (D.D.), University of Minnesota, Minneapolis
3. Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, NC (A.G.B.)
4. Division of Biostatistics, University of Minnesota School of Public Health, Minneapolis (W.G.).