1. GI Physiology Laboratory; University of Michigan Health System; Ann Arbor; MI; USA
2. Division of Gastroenterology & Hepatology, University of North Carolina Center for Functional GI and Motility Disorders; University of North Carolina at Chapel Hill; Chapel Hill; NC; USA
3. University of Illinois; College of Medicine at Rockford; Rockford; IL; USA
4. Sucampo Pharmaceuticals, Inc.; Bethesda; MD; USA