Clinical Studies on Bile Acids Barretts Esophagus
Patients who have been scheduled for elective endoscopic examination at the Dallas VA Medical Center for the evaluation of GERD or Barretts esophagus will be invited to participate in the study. Patients who provide written, informed consent will have a medical history taken. Women of child bearing potential will have a pregnancy test. Eligible subjects will be treated with omeprazole 20 mg BID for at least four weeks before the scheduled endoscopic examination. Eight days before the endoscopy, patients will be instructed to discontinue any aspirin and other non-steroidal anti-inflammatory drugs (unless there is a contraindication to discontinuing those medications including a history of coronary artery disease, myocardial infarction, cerebrovascular accident or transient ischemic attacks). The endoscopic examination, which had been scheduled for clinical purposes, will be performed as usual, with biopsy specimens taken as required for clinical purposes. When the clinical examination has been completed, a perfusion catheter will be passed through the biopsy channel and positioned 5 cm above the squamocolumnar junction in the distal esophagus. The distal esophagus will be perfused with 10cc of a 250 μM solution of either DCA or UDCA for 5 minutes. Odd-number patients enrolled in each of the two patient groups (GERD patients with and without Barretts esophagus) will receive DCA, whereas even-number patients will receive UDCA. The catheter position, bile acid concentration and duration of bile acid perfusion are chosen to simulate a typical episode of gastroesophageal reflux. In all patients, 12 biopsy specimens of the squamous epithelium will be taken using jumbo biopsy forceps at a level 2 cm proximal to the squamocolumnar junction at baseline (6 biopsies will be used to establish the primary cell cultures and six will be used for the molecular analyses); 6 more biopsy specimens will be taken at the same level immediately after bile acid perfusion for molecular analyses. In the patients with Barretts esophagus, 12 biopsy specimens of the specialized intestinal metaplasia also will be taken using jumbo biopsy forceps at a level 1 cm distal to the squamocolumnar junction at baseline (6 biopsies will be used to establish the primary cell cultures and six will be used for the molecular analyses); 6 more biopsy specimens will be taken at the same level immediately after bile acid perfusion for molecular analyses. All endoscopic procedures will be performed by S.J. Spechler.
All patients will be maintained on omeprazole 20 mg BID for one year, after which the endoscopic examinations will be repeated. The endoscopies will be performed with bile acid perfusions and biopsy sampling exactly as described above, except that patients who received DCA during the first examination will receive UDCA and vice versa. All biopsy specimens will be used for molecular analyses.