1. Division of Gastroenterology and Hepatology, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States
2. Division of Gastroenterology and Hepatology, University of North Carolina, Chapel Hill, North Carolina, United States
3. Borland-Groover Clinic, Jacksonville, Florida, United States
4. Division of Gastroenterology and Hepatology, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan