1. Center for Esophageal Diseases and Swallowing; Division of Gastroenterology and Hepatology; Department of Medicine; University of North Carolina School of Medicine; Chapel Hill NC USA
2. Center for Gastrointestinal Biology and Disease; Division of Gastroenterology and Hepatology; Department of Medicine; University of North Carolina School of Medicine; Chapel Hill NC USA
3. Department of Clinical Epidemiology; Aarhus University Hospital; Aarhus Denmark
4. Institute of Pathology; Aalborg Hospital; Aalborg Denmark