1. Department of Gastroenterology, Gunma Saiseikai Maebashi Hospital, Maebashi 371-0821, Japan
2. Department of Gastroenterology, Hanwa Memorial Hospital, Osaka 558-0041, Japan
3. Department of Gastroenterology, National Hospital Organization Takasaki General Medical Center, Takasaki 370-0829, Japan
4. Department of Clinical Research, National Hospital Organization Takasaki General Medical Center, Takasaki 370-0829, Japan
5. Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Maebashi 371-8511, Japan