[1] Walter Reed Army Med Ctr, Dept Med, Div Gastroenterol, Washington, DC 20307 USA
[2] Wilford Hall USAF Med Ctr, Dept Med, Div Gastroenterol, San Antonio, TX USA
[3] Wilford Hall USAF Med Ctr, Dept Pathol, San Antonio, TX USA
[4] Brooke Army Med Ctr, Dept Clin Invest, Ft Sam Houston, TX 78234 USA
[5] Brooke Army Med Ctr, Dept Med, Div Gastroenterol, Ft Sam Houston, TX 78234 USA