1. From the Departments of Anatomy and Cell Biology (R.L.D., D.S.H., G.M.B.), Anesthesia (G.A., J.N.B.), Pathology (S.S.), and Internal Medicine and Veterans Affairs (R.M.W.), University of Iowa College of Medicine, Iowa City; the Department of Biological Sciences (G.S.), University of Kansas, Lawrence; and the Department of Obstetrics and Gynecology (D.C.M.), Wake Forest School of Medicine, Wake Forest, NC.