1. Division of Gastroenterology and Hepatology; University of Nebraska Medical Center; Omaha Nebraska USA
2. Division of Gastroenterology; Louisiana State University Health Science Center; Shreveport Louisiana USA
3. Department of Environmental Health and Engineering; Johns Hopkins Bloomberg School of Public Health; Baltimore Maryland USA
4. Department of Family Medicine and Preventive Medicine; Prince of Songkhla University; Songkhla Thailand
5. Department of Internal Medicine; Methodist Physicians Clinic; Council Bluffs Iowa USA
6. Department of Internal Medicine; Bassett Medical Center; Cooperstown New York USA