1. Radboud University Medical Centre, Nijmegen
2. Franciscus Gasthuis & Vlietland, Rotterdam
3. Medical Spectrum Twente, Enschede
4. Onze Lieve Vrouwe Gasthuis, Amsterdam
5. Jeroen Bosch Hospital, ’s-Hertogenbosch, The Netherlands
6. Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Canada