[1] Stanford Univ, Sch Med, Div Gastroenterol, Stanford, CA 94305 USA
[2] Stanford Univ, Biodesign Program, Stanford, CA 94305 USA
[3] Stanford Univ, Sch Med, Div Cardiovasc Med, Stanford, CA 94305 USA
[4] Stanford Univ, Sch Med, Dept Surg, Stanford, CA 94305 USA
[5] Johns Hopkins Sch Med, Div Gastroenterol, Baltimore, MD USA