1. Medical Department II, Klinikum rechts der Isar, Technical University of Munich, D-81675 Munich, Germany, Institute of Pathology and Department of Gastroenterology and Hepatology, Otto-von-Guericke University, D-39120 Magdeburg, Germany, and Departments of Medicine, and Pharmacology and Toxicology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756