[1] Univ Pittsburgh, Dept Med, Div Gastroenterol Hepatol & Nutrit, Pittsburgh, PA 15261 USA
[2] Univ Pittsburgh, Dept Mol Genet & Biochem, Pittsburgh, PA 15261 USA
[3] Univ Pittsburgh, Dept Cell Biol & Physiol, Pittsburgh, PA 15261 USA
[4] VA Pittsburgh Hlth Care Syst, Pittsburgh, PA USA