[1] Univ Sao Paulo, Hosp Clin, Gastrointestinal Endoscopy Unit, Av Dr Eneas de Carvalho Aguiar 255,6 Andar, BR-05403000 Sao Paulo, Brazil
[2] Harvard Med Sch, Brigham & Womens Hosp, Div Gastroenterol Hepatol & Endoscopy, Boston, MA 02115 USA
[3] McGill Univ, Div Gastroenterol & Hepatol, Hlth Ctr, Montreal, PQ, Canada
[4] Univ Santo Amaro, Rua Isabel Schmidt 349, BR-04743030 Sao Paulo, SP, Brazil
[5] Johns Hopkins Med, Div Gastroenterol & Hepatol, Baltimore, MD USA