1. Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California;
2. Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California;
3. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut;
4. Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut; and
5. Veterans Affairs Healthcare System, West Haven, Connecticut