[1] Univ Nacl Autonoma Mexico, Hosp Gen Mexico, Fac Med, Dept Expt Med, Mexico City 06726, DF, Mexico
[2] Dept Internal Med, Mexico City 14000, DF, Mexico
[3] Inst Nacl Ciencias Med & Nutr Salvador Zubiran, Dept Gastroenterol, Mexico City 14000, DF, Mexico