1. Division of Gastrointestinal Hormones, Department of Surgery, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0558, Biomeasure, Inc., 27 Maple Street, Milford, Massachusetts 01757-3650, Department of Surgery, UCLA School of Medicine, Los Angeles, California 90095-6904, and INSERM 410, Faculty of Medicine X, BICHAT, 75870 Paris Cedex, France