1 Department of Internal Medicine, Wonkwang University College of Medicine, Iksan, Korea.
2 Institute of Wonkwang Medical Science, Wonkwang University College of Medicine, Iksan, Korea.
3 Division of Gastroenterology and Hepatology, Johns Hopkins University, Baltimore, MD, USA.
4 Department of Internal Medicine, Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Korea.