1. Department of Gastroenterology and Hepatology, Uonuma Institute of Community Medicine, Niigata University Medical and Dental Hospital, Minamiuonuma 949-7302, Niigata, Japan
2. Department of Preemptive Medicine for Digestive Diseases and Healthy Active Life, School of Medicine, Niigata University, Niigata 951-8510, Niigata, Japan
3. Department of Gastroenterology and Hepatology, Tsubame Rosai Hospital, Tsubame 959-1228, Niigata, Japan
4. Department of General Medicine, School of Medicine, Niigata University, Niigata 951-8510, Niigata, Japan
5. Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA