1. Degenerative Diseases Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
2. Soonchunhyang Institute of Med-Bio Science, Soonchunhayng University, Cheonan-si, Choongchengnam-do 330-930, Republic of Korea
3. Division of Geriatrics and Nutrition Sciences, Washington University School of Medicine, St. Louis, MO 63110
4. Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110