[1] HARVARD UNIV,BRIGHAM & WOMENS HOSP,SCH MED,DEPT MED GASTROENTEROL,BOSTON,MA 02115
[2] HARVARD UNIV,BRIGHAM & WOMENS HOSP,SCH MED,DEPT PATHOL,BOSTON,MA 02115
[3] UNIV PITTSBURGH,MONTEFIORE HOSP,SCH MED,PITTSBURGH,PA 15213
[4] NEWTON WELLESLEY HOSP,NEWTON LOWER FALLS,MA 02162
[5] TUFTS UNIV,SCH MED,BOSTON,MA 02111