In this project, we are trying to identify patients with the earliest signs of abnormality in the lining of the lower part of the food pipe (or esophagus) known as intestinal metaplasia (IM); also commonly called Barrett's esophagus or Barrett's Epithelium (BE). IM is sometimes difficult to diagnose by routine microscopic examination (called histology). We have developed a specific antibody, a protein called immunoglobulin that specifically reacts with another partner protein, if it exists. Using this marker antibody (called mAb Das-1) that has been patented (US patent #5,888,743), we have shown that this marker can detect the abnormal changes in the distal esophagus before it is evident by histology. IM usually develops in the face of long-term acid reflux from the stomach to the esophagus and causes the lining to change from the normal squamous type (like that of skin) to a type of lining normally seen in the small intestine and colon. A subgroup of patients with IM may, subsequently, develop histologically evident Barrett's Epithelium and a small percent of these patients may develop cancer of the esophagus. Thus, BE is considered as a pre-cancerous condition. We already have an ongoing IRB for the portion of the project involving taking biopsies and performing the antibody staining to identify patients that react with the antibody but histologically negative for BE.