How to Make a Barrett Esophagus: Pathophysiology of Columnar Metaplasia of the Esophagus

Barrett esophagus is defined as a specialized intestinal replacing the squamous epithelium of the esophageal mucosa in response to gastroesophageal reflux. Barrett metaplasia is a healing process that develops to protect the esophagus from further damage. Although mechanisms by which Barrett metaplasia evolves toward dysplasia and adenocarcinoma have been extensively studied, the process by which squamous epithelium is replaced by specialized intestinal metaplasia is poorly understood. Barrett esophagus develops when defense mechanisms in the esophageal mucosa (luminal secretion of mucus, bicarbonate, growth factors, etc.) are overwhelmed by an ongoing cycle of mucosal injury and repair. Hydrogen ion, pepsin, trypsin, and bile acids are considered harmful agents that synergistically invade the esophageal mucosa. Areas of destroyed squamous epithelium are then progressively reepithelized by a columnar epithelium that may originate from multipotent stem cells located within the basal layer of the normal esophageal mucosa or in the ducts of submucosal glands.     

TP53 mutations in malignant and premalignant Barrett''s esophagus

In order to improve the efficacy of endoscopic surveillance of Barrett's esophagus, markers of neoplastic progression in addition to dysplasia are required. The aim of the present study was to assess TP53 mutational analysis as a method of identifying patients with Barrett's esophagus who are at greatest risk of adenocarcinoma, for whom endoscopic surveillance is most appropriate. TP53 mutational analysis was initially performed on premalignant and malignant tissue from 30 patients undergoing esophagectomy for adenocarcinoma, and on premalignant biopsies from 48 patients participating in a Barrett's surveillance program. Surveillance patients were followed up endoscopically and histologically for a median of 5 years following TP53 assessment. Mutational analysis was performed by single-strand conformation polymorphism analysis and direct DNA sequencing. TP53 mutations were detected in 10 of 30 esophageal adenocarcinomas, and were more common in well-differentiated carcinomas. An identical TP53 mutation was detected in carcinoma and adjacent dysplasia. Two patients with premalignant Barrett's esophagus had TP53 mutations and one of these patients developed adenocarcinoma on follow up whilst the other has not yet progressed beyond metaplasia. No patient without TP53 mutation developed high-grade dysplasia or adenocarcinoma. TP53 mutations are detected in 33% of esophageal adenocarcinomas and in 4% of premalignant Barrett's esophagus in patients undergoing endoscopic surveillance. TP53 mutation can be detected before the development of high-grade dysplasia or carcinoma, and may be useful in stratifying the risk of adenocarcinoma in patients with Barrett's esophagus.     

Reflux injury of esophageal mucosa: experimental studies in animal models of esophagitis, Barrett''s esophagus and esophageal adenocarcinoma

Barrett's esophagus (BE), a gastroesophageal reflux associated complication, is defined as the replacement of normal esophageal squamous mucosa by specialized intestinal columnar mucosa with the appearance of goblet cells. The presence of BE is associated with an increased risk of developing esophageal adenocarcinoma (EAC). Although the exposure of gastroduodenal contents to the esophageal mucosa is considered to be an important risk factor for the development of esophagitis, BE and EAC, the mechanisms of reflux esophageal injury are not fully understood. Animal models are now being used extensively to identify the mechanisms of damage and to devise protective and mitigating strategies. Experimental studies on animal models by mimicking the processing of gastroesophageal reflux injury have bloomed during the past decades, however, there is controversy regarding which experimental model for reflux esophagitis, experimental BE and experimental EAC is best. In this review article we aim to clarify the basic understanding of gastroesophageal reflux injury and its complications of BE and EAC, as well as to present current understanding of the reflux experimental models. The animal models of experimental esophageal injury are summarized with focus on the surgical procedures to guide the investigator in choosing or developing a correct animal model in future studies. In addition, our own experimental studies of the animal models are also briefly discussed.     

Elevated gastric acid secretion in patients with Barrett's metaplastic epithelium

Gastric acid secretion in response to a protein meal and to exogenously administered synthetic human gastrin 17-I was measured in patients with Barrett's esophagus, patients with uncomplicated gastroesophageal reflux, and normal age- and sex-matched controls. Acid secretion, both basally and in response to gastrin 17-I, was significantly greater in patients with Barrett's esophagus compared to normal individuals without reflux. Basal gastrin levels and meal-stimulated levels of the hormone were similar among all three groups. Sensitivity to gastrin, expressed as the concentration causing half-maximal acid secretion, was also similar among the study groups. It is speculated that elevated basal acid production in Barrett's esophagus may contribute to the pathogenesis of the disorder.Study supported by Smith, Kline, and French, Inc.     

Oral Nitroglycerin Solution May Be Effective for Esophageal Food Impaction

Background

Esophageal food impaction is a common illness presenting to emergency departments (ED), and is frequently resistant to pharmacologic therapy. Several medications have been promoted for this indication, but so far have not proven effective. Endoscopic removal is frequently required to resolve the impaction, resulting in risks from anesthesia and the physical procedure, and in prolonged hospital stay for recovery. Oral nitroglycerin solution was recently used in two such cases and may represent a new therapeutic option.

上消化道胶囊内镜发展与创新北大核心CSCD

上消化道疾病高发,传统插管式胃镜是检查上消化道疾病最常用的检查方法和"金标准"。为了更舒适无创的检查上消化道黏膜,多项研究提出了上消化道胶囊内镜的概念,但是由于上消化道各部位解剖与生理结构的差异,目前可以使用的胶囊内镜如单纯被动式、磁控式、线控式、磁控联合线控式以及侧视胶囊内镜都存在一定的局限性,无法实现对上消化道整体黏膜情况的观察。文章试图通过介绍适用于食管、胃以及十二指肠检测的胶囊内镜,分析各内镜的诊断效能及其不足,探讨未来上消化道胶囊内镜可能的发展方向。     

The Effect of Retinoic Acid and Deoxycholic Acid on the Differentiation of Primary Human Esophageal Keratinocytes

The mechanism linking gastroduodenal reflux disease to intestinal metaplasia in the esophagus (Barrett’s esophagus) has not been determined. Active conjugate metabolites of retinoic acid, in addition to bile acids, undergo an enterohepatic circulation in bile. Retinoic acid and bile acids are candidate mediators of keratinocyte transdifferentiation in Barrett’s esophagus. We studied the effects of retinoic acid on the differentiation of primary human esophageal keratinocytes cultured in vitro. Retinoic acid induces expression of a marker of intestinal differentiation, MUC2, in these cells. However, retinoic acid, alone or in combination with the hydrophobic bile acid, deoxycholic acid, does not affect esophageal keratinocyte squamous differentiation as assessed by involucrin expression and cellular morphology. The ability of retinoic acid to induce MUC2 expression may be relevant to the pathogenesis of Barrett’s esophagus. However, this does not result in suppression of squamous differentiation.     

Experimental reconstruction of dog's esophagus with biotype artificial esophagus

OBJECTIVE: At present, there are few materials available for esophagus reconstruction anywhere in the world. The reported survival rate in animals during the perioperative period is comparatively low. The present study assessed the feasibility of using a biotype artificial esophagus in the reconstruction of a dog's esophagus. METHODS: In 30 mongrel dogs, a portion of the thoracic esophagus was resected and an 8 cm section of artificial esophagus was transplanted to reconstruct the organ. The survival rate, food intake and process of healing were observed. RESULTS: Of the 30 dogs, 28 survived the peri­operative period (93.3% survival). Two dogs (6.7%) developed an anastomotic fistula; 19 dogs survived for 1 year, a survival rate of 79.2% (19/24) with the remaining six dogs were killed according to the experimental protocol. Detachment of the artificial esophagus occurred on average 28.8 days after operation and the dogs suffered from varying degrees of dysphagia 23?45 days after operation. Gradual remission occurred after 4 months. The histological study revealed that the regenerated esophagus was composed of fibrous and connective tissues and the luminal surface was covered with squamous epithelium in 3?6 months. CONCLUSION: The transplanted artificial esophagus detached after the surrounding ‘regenerated esophagus’ had formed, and the squamous epithelium gradually covered the luminal surface. Continuous remodeling of the ‘regenerated esophagus’ gradually relieved the stenosis. Whether detachment of the implant and the postoperative stenosis can be solved is the key problem restricting the use of the biotype artificial esophagus in clinical practice.     

Two-field lymph-node dissection may be enough to treat patients with submucosal squamous cell carcinoma of the thoracic esophagus

Significance of extended radical surgical treatment including three-field lymph node dissection for squamous cell carcinoma (SCC) of the esophagus remains debatable. The aim of the current study was to reconsider the merits and demerits obtained by three-field lymph node dissection for esophageal carcinoma and also to attempt to elucidate an appropriate surgical strategy for submucosal SCC of the thoracic esophagus. Thirty-one patients with SCC of the thoracic esophagus who had been treated with esophagectomy and two-field (thoracic and abdominal) lymph node dissection without preoperative therapies were enrolled. Five-year survival rate was 75.0% and the incidence proportion of postoperative complication was 9.7%. These data regarding postoperative outcome of patients were by no means inferior to those in the previous reports referring the prognosis of patients with esophageal carcinoma who had been treated with three-field lymph node dissection. Authors would like to mention that two-field lymph node dissection associated with reduced incidence of postoperative complications might be enough to treat the submucosal SCC of the thoracic esophagus.