1 Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of South Carolina, Charleston, SC, USA.
2 Ralph H Johnson Veterans Affairs Medical Center, Charleston, SC, USA.
3 Department of Physiology, Faculty of Medicine and Nursing, University of Basque Country UPV/EHU, Leioa, Spain.
4 Division of Cardiology, Department of Internal Medicine, Medical University of South Carolina, 114 Doughty Street, Charleston, SC, 29412, USA. litwins@musc.edu.
5 Ralph H Johnson Veterans Affairs Medical Center, Charleston, SC, USA. litwins@musc.edu.