[1] UNIV CHICAGO, SCH MED, CHICAGO, IL 60637 USA
[2] NW GASTROENTEROLOGISTS, ARLINGTON HTS, IL USA
[3] TUFTS UNIV NEW ENGLAND MED CTR, BOSTON, MA USA
[4] AUSTIN DIAGNOST CLIN, AUSTIN, TX USA
[5] SAN FRANCISCO GEN HOSP, SAN FRANCISCO, CA USA
[6] NALLE CLIN, CHARLOTTE, NC USA
[7] GASTROINTESTINAL ASSOC PA, SHAWNEE MISSION, KS USA
[8] HCA PRESBYTERIAN HOSP, OKLAHOMA CITY, OK USA
[9] FORSYTH MED SPECIALISTS, WINSTON SALEM, NC USA
[10] DIGEST HEALTHCARE, MINNEAPOLIS, MN USA
[11] GREATER CINCINNATI GASTROENTEROL ASSOCIATES, CINCINNATI, OH USA
[12] GASTROENTEROL LAKE CITY, WAUKEGAN, IL USA
[13] VALLEY HLTH CARE MED GRP, BINGHAMTON, NY USA
[14] SCRIPPS CLIN MED GRP INC, LA JOLLA, CA USA
[15] OREGON HLTH SCI UNIV, PORTLAND, OR USA
[16] VIRGINIA COMMONWEALTH UNIV, MED COLL VIRGINIA, RICHMOND, VA 23298 USA
[17] WAKE RES ASSOC, RALEIGH, NC USA
[18] BIRMINGHAM GASTROENTEROL ASSOCIATES, BIRMINGHAM, AL USA
[19] WAKE FOREST UNIV, BOWMAN GRAY SCH MED, WINSTON SALEM, NC USA
[20] MARION MERRELL DOW INC, KANSAS CITY, MO USA