1. Department of Gastroenterology, Aizu Medical Center, Fukushima Medical University, Fukushima, Japan
2. Department of Gastroenterology, Juntendo University, Tokyo, Japan
3. Department of Gastroenterology, Dokkyo Medical University, Tochigi, Japan
4. Department of Surgery, Aizu Medical Center, Fukushima Medical University, Fukushima, Japan
5. Department of Pathology, Aizu Medical Center, Fukushima Medical University, Fukushima, Japan