1. Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
2. Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, Netherlandsf
3. Departamento de Gastroenterologia, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
4. Department of Internal Medicine, University Hospital Knappschaftskrankenhaus, Ruhr-University Bochum, Bochum, Germany