1. From the Gastrointestinal Unit, Department of Paediatrics, University of Berne, Berne, Switzerland, the Universitäts-Kinderklinik Bonn, Bonn, Germany, the Children's Hospital, University of Helsinki, Helsinki, Finland, and the Unité de Recherches Médicale INSERM, Hôpital des Enfants Malades, Paris, France (address reprint requests to Dr. Hadorn at the University Children's Hospital Berne, Freiburgstrasse 23, CH-3010 Berne, Switzerland).