 PRELIMINARY STUDIES At this time, preliminary data have been collected from the 4 participating centers, and merged into one single databank. These preliminary results were presented at the plenary sessions 45,46 of the American Gastroenterological Association AGA annual meeting in Atlanta, GA May 2001 and at the American College of Gastroenterology ACG annual meeting in Las Vegas, NV October 2001, indicating a common interest amongst the investigators and capability of working together. 