[1] Univ Sao Paulo, Gastrointestinal Endoscopy Unit, Sch Med, Av Dr Eneas Carvalho Aguiar 255, BR-05403010 Sao Paulo, SP, Brazil
[2] Harvard Med Sch, Brigham & Womens Hosp, Div Gastroenterol Hepatol & Endoscopy, Boston, MA 02115 USA
[3] Univ Sao Paulo, Div Gastrointestinal Endoscopy, Med Sch, BR-01246903 Sao Paulo, SP, Brazil