1. Department of Surgery, Division of Transplantation, University of Wisconsin School of Medicine and Public Health; and William S. Middleton Memorial VA Hospital; Madison, WI 53792.
2. Present address: Altonaer Kinderkrankenhaus, Bleickenallee 38, 22763 Hamburg, Germany.
3. Department of Surgery, Division of Transplantation, University of Wisconsin School of Medicine and Public Health; William S. Middleton Memorial VA Hospital; and The WiCell Research Institute, Madison, WI 53792.