Division of Gastroenterology;
Department of Internal Medicine;
Sapporo Shirakaba-dai Hospital;
Department of Gastroenterology;
Sapporo Medical University;
The Institute of Medical Science Hospital;
The University of Tokyo;
Department of Public Health;
Sapporo Medical University;
School of Medicine;
Department of Preventive Medicine;
Nagoya University;
Graduate School of Medicine;
Department of Hygiene and Preventive Medicine;
Iwate Medical University School of Medicine;
Department of Public Health;
Hokkaido University School of Medicine;