[1] Baylor Coll Med, Gastroenterol & Hepatol Sect, Houston, TX 77030 USA
[2] East Carolina Univ, Div Gastroenterol, Dept Internal Med, Greenville, NC USA
[3] Texas Tech Univ, Hlth Sci Ctr, Paul L Foster Sch Med, Dept Pathol, El Paso, TX USA
[4] Texas Tech Univ, Hlth Sci Ctr, Div Gastroenterol, Dept Internal Med,Paul L Foster Sch Med, El Paso, TX USA