1. Ferring Research Institute Inc., San Diego, California 92121, Department of Pediatrics, University of Geneva, School of Medicine, 1211 Geneva 14, Switzerland, Ferring Research Institute Ltd., Southampton SO16 7NP, U.K., Ferring SAS, 216 Boulevard Saint Germain, 75007 Paris, France, and The Salk Institute, La Jolla, California 92037