[1] Univ Nacl Autonoma Mexico, Hosp Gen Mexico, Dept Expt Med,HIPAM, Fac Med,Liver Pancreas & Motil Lab, Mexico City 06726, DF, Mexico
[2] Univ Autonoma Metropolitana Iztapalapa, Dept Hlth Sci, Mexico City, DF, Mexico
[3] Univ Autonoma Metropolitana Iztapalapa, Ctr Medico Nacl Siglo XXI, Dept Internal Med, Mexico City, DF, Mexico
[4] Univ N Carolina, Div Gastroenterol, Chapel Hill, NC USA