1. Division of Gastroenterology and Hepatology Department of Medicine School of Medicine Indiana University Indianapolis IN USA
2. Richard L. Roudebush VA Medical Center Indianapolis IN USA
3. Department of Medical Physiology Texas A&M University Bryan TX USA
4. Eleonora Lorillard Spencer Cenci Foundation Rome Italy
5. Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences Sapienza University of Rome Rome Italy