1. Division of Gastroenterology and Hepatology; Department of Medicine; Feinberg School of Medicine; Northwestern University; Chicago IL USA
2. Université de Lyon; Hospices Civils de Lyon; Digestive Physiology; Hopital E Herriot; F-69437 LYON France
3. Université de Lyon; Lyon I University; Digestive Physiology; F-69008 LYON France
4. Université de Lyon; Inserm U1032; F-69008 LYON France