Bile acid accumulation by rabbit esophageal mucosa

Pyloroplasty and the risk of Barrett's esophagus in patients with gastroparesis

Barrett's esophagus (BE), a consequence of gastroesophageal reflux disease (GERD), is a premalignant condition for esophageal adenocarcinoma. Impaired gastric emptying leads to increased gastric volume and therefore more severe reflux. We seek to investigate the association between gastroparesis and BE and the predictors of BE among patients with gastroparesis. This is a retrospective review of patients seen at Cleveland Clinic between 2011 and 2016 who had an upper endoscopy and a gastric emptying study. Demographics, symptoms, medications, endoscopic and histological findings, and therapeutic interventions were abstracted. Risk of BE among gastroparesis group and control group was assessed, and logistic regression analysis was performed to identify predictors of BE among gastroparesis patients. Of the 4,154 patients, 864 (20.8%) had gastroparesis and 3, 290 (79.2%) had normal gastric emptying. The mean age was 51.4 ± 16.4 years, 72% were women and 80% were Caucasians. Among the gastroparesis group, 18 (2.1%) patients had BE compared to 71 (2.2%) cases of BE in the control group, P = 0.89. There were no differences in gender, race, reflux symptoms, or esophageal findings between the two groups. Among gastroparesis group, predictors of developing BE were a history of alcohol use (odds ratio [OR] 6.76; 95% confidence intervals [CI]: 1.65-27.67, P = 0.008), history of pyloroplasty (OR: 8.228; CI: 2.114-32.016, P = 0.002), and hiatal hernia (OR: 8.014; CI: 2.053-31.277, P = 0.003). Though gastroparesis is a known contributing factor for GERD, there was no increased prevalence of BE in gastroparesis. Among patients with gastroparesis, predictors of BE are history of alcohol use, hiatal hernia, and pyloroplasty.

Gastroesophageal reflux-related physiologic changes after sleeve gastrectomy and Roux-en-Y gastric bypass: a prospective comparative study

BACKGROUND

The development of gastroesophageal reflux disease (GERD) after laparoscopic sleeve gastrectomy (LSG) is a major concern as it affects the quality of life of the patients and potentially exposes them to the complications of GERD. The reported incidence of GERD after LSG is up to 35%. Laparoscopic Roux-en-Y gastric bypass (LRYGB) is considered the procedure of choice for patients with morbid obesity with GERD but objective evidence based on physiologic studies for the same are limited.

OBJECTIVE

The objectives of the study were to determine the physiologic changes related to gastroesophageal reflux based on symptoms index, 24-hour pH study, impedance, and manometry after LSG and LRYGB.

SETTINGS

Tertiary care teaching hospital, India.

METHODS

This registered study (CTRI/2017/06/008834) is a prospective, nonrandomized, open-label clinical trial comparing the incidence of GERD after LSG and LRYGB. In this study, non-GERD patients were evaluated for GERD based on clinical questionnaires, 24-hour pH study, and impedance manometry preoperatively and 6 months postoperatively.

RESULTS

Thirty patients underwent LSG, and 16 patients underwent LRYGB. The mean DeMeester score increased from 10.9 ± 11.8 to 40.2 ± 38.6 (P = .006) after LSG. The incidence of GERD after LSG was 66.6%. The increase in DeMeester score from 9.5 ± 4.6 to 12.2 ± 17.2 after LRYGB was not significant (P = .7). There was a significant increase in the nonacid reflux both after LSG and LRYGB.

CONCLUSION

The incidence of GERD after LSG is high, making it a contraindication for LSG. LRYGB remains the preferred procedure for patients with GERD. However, more studies are needed to understand the physiologic changes in patients with preexisting GERD.

The Role of Acid Suppression in Barrett's Esophagus

In recent years, proton pump inhibitors (PPIs) have come under great scrutiny due to possible adverse, long-term side effects. At the same time, Barrett's esophagus, a premalignant condition in the esophagus, continues to be a disease whose course is thought to be improved by the use of PPIs. We review the impact of proton pump therapy on the esophagus and on Barrett's mucosa. In analyzing changes on a cellular level, we explore the effect of mixed gastric refluxate and the complex cascade that ensues with esophageal exposure of these contents. Because the incidence of esophageal adenocarcinoma is on the rise, we explore other factors that may contribute to the progression of Barrett's from non-dysplastic mucosa to esophageal adenocarcinoma. By revisiting the need for adequate acid suppression in Barrett's and increasing our understanding of other possible factors that may have an effect of Barrett's progression, we hope to support our multifaceted approach to acid suppression in patients with Barrett's esophagus.

Role of ion transporters in the bile acid-induced esophageal injury

Barrett's esophagus (BE) is considered to be the most severe complication of gastro-esophageal reflux disease (GERD), in which the prolonged, repetitive episodes of combined acidic and biliary reflux result in the replacement of the squamous esophageal lining by columnar epithelium. Therefore, the acid-extruding mechanisms of esophageal epithelial cells (EECs) may play an important role in the defense. Our aim was to identify the presence of acid/base transporters on EECs and to investigate the effect of bile acids on their expressions and functions. Human EEC lines (CP-A and CP-D) were acutely exposed to bile acid cocktail (BAC) and the changes in intracellular pH (pHi) and Ca(2+) concentration ([Ca(2+)]i) were measured by microfluorometry. mRNA and protein expression of ion transporters was investigated by RT-PCR, Western blot, and immunohistochemistry. We have identified the presence of a Na(+)/H(+) exchanger (NHE), Na(+)/HCO3 (-) cotransporter (NBC), and a Cl(-)-dependent HCO3 (-) secretory mechanism in CP-A and CP-D cells. Acute administration of BAC stimulated HCO3 (-) secretion in both cell lines and the NHE activity in CP-D cells by an inositol triphosphate-dependent calcium release. Chronic administration of BAC to EECs increased the expression of ion transporters compared with nontreated cells. A similar expression pattern was observed in biopsy samples from BE compared with normal epithelium. We have shown that acute administration of bile acids differently alters ion transport mechanisms of EECs, whereas chronic exposure to bile acids increases the expression of acid/base transporters. We speculate that these adaptive processes of EECs represent an important mucosal defense against the bile acid-induced epithelial injury.

Pathophysiology of gastro-esophageal reflux disease: a role for mucosa integrity?

BACKGROUND

Gastro-esophageal reflux disease (GERD) is very prevalent and has a high burden on health security system costs. Nevertheless, pathophysiology is complex and not well-understood. Several mechanisms have been proposed: decreased salivation, impaired esophageal clearance, decreased lower esophageal sphincter pressure resting tone, presence of hiatal hernia, increased number of transient lower esophageal sphincter relaxations (TLESRs), increased acid, and pepsin secretion, pyloric incompetence provoking duodeno-gastro-esophageal reflux of bile acids and trypsin. Independent of the relevance of each mechanism, the ultimate phenomenon is that mucosal epithelium is exposed for a longer time to agents as acid and pepsin or is in contact to luminal agents not commonly present in gastric refluxate as trypsin or bile acids. This leads to a visible damage of the epithelium (erosive esophagitis -EE) or impairing mucosal integrity without any sign of macroscopic alteration as occurs in non-erosive reflux disease (NERD). Luminal factors are not the only responsible for such impairment; more recent data indicate that endogenous factors may also play a role.

PURPOSE

This review will update the most recent findings on the putative pathophysiological mechanisms and specially will focus on the role of esophageal mucosal integrity in GERD. Methodologies used for the evaluation of mucosal integrity, its relevance in EE and NERD, its involvement in symptoms perception and the effect of luminal and endogenous factors will be discussed.

Intraluminal pH and goblet cell density in Barrett's esophagus

INTRODUCTION

Goblet cells in Barrett's esophagus (BE) vary in their density within the Barrett's segment. Exposure of Barrett's epithelium to bile acids is a major stimulant for goblet cell formation. The dissociation of bile acids into forms that penetrate Barrett's epithelium is known to be pH dependent. We hypothesized that variations in the esophageal luminal pH environment explains the variability in goblet cell density. The aim of this study was to correlate esophageal luminal pH with goblet cell density in patients with BE.

METHODS

A customized six-sensor pH catheter was positioned with the most distal sensor in the stomach and the remaining sensors located 1 cm below and 1, 3, 5, and 8 cm above the upper border of the lower esophageal sphincter in five normal subjects and six patients with long-segment BE. The luminal pH was measured by each sensor for 24-h and expressed as median pH. Patients with BE had four quadrant biopsies at levels corresponding to the location of the pH sensors. Goblet cell density was graded from 0 to 3 based on the number per high-power field.

RESULTS

In normal subjects, the median pH values recorded in the sensors within the lower esophageal sphincter (LES) and esophageal body were all above 5. In patients with BE, the median pH recorded by the sensor within the LES was 2.8 and increased progressively to 4.7 in the sensor at 8 cm above the LES. Goblet cell density was significantly lower in the distal Barrett's segment exposed to a median pH of 2.2 and increased in the proximal Barrett's segment exposed to a median pH of 4.4 (p = 0.003).

CONCLUSION

Patients with BE have a goblet cell gradient that correlates directly with an esophageal luminal pH gradient. This suggests that goblet cell differentiation is pH dependent and likely due to the effect of pH on bile acid dissociation.

Does impaired gallbladder function contribute to the development of Barrett's esophagus and esophageal adenocarcinoma?

INTRODUCTION

Esophageal adenocarcinoma is aetiologically associated with gastro-esophageal reflux, but the mechanisms responsible for the metaplasia-dysplasia sequence are unknown. Bile components are implicated. Impaired gallbladder function may contribute to duodenogastric reflux (DGR) and harmful GERD.

AIMS

This study aims to compare gallbladder function in patients with Barrett's esophagus, adenocarcinoma, and controls.

METHODS

Three groups of patients, all free of gallstone disease, were studied. Group 1: (n = 15) were normal controls. Group 2: (n = 15) were patients with >3-cm-long segment of Barrett's esophagus. Group 3: (n = 15) were patients with esophageal adenocarcinoma. Using real-time ultrasonography unit, gallbladder volume was measured in subjects following a 10-h fast. Ejection fraction was calculated before and after standard liquid meal and compared between the groups.

RESULTS

The mean percentage reduction in gallbladder volume was 50% at 40 min in the adenocarcinoma group compared with 72.4% in the control group (p < 0.001). At 60 min, gallbladder filling had recommenced in the control group to 64.1% of fasting volume while continuing to empty with further reduction to 63% in the Barrett's group and to 50.6% (p = 0.008) in the adenocarcinoma group. The mean gallbladder ejection fraction decreased progressively from controls to Barrett's to adenocarcinoma and was significantly lower in Barrett's group (60.9%; p = 0.019) and adenocarcinoma group (47.9%; p < 0.001) compared with normal controls (70.9%).

CONCLUSION

Gallbladder function is progressively impaired in Barrett's esophagus and adenocarcinoma. Gallbladder malfunction increases duodenogastric reflux, exposing the lower esophagus to an altered chemical milieu which, in turn, may have a role in promoting metaplasia-dysplasia-neoplasia sequence in the lower esophageal mucosa.

Response of cricopharyngeus muscle to esophageal stimulation by mechanical distension and acid and bile perfusion

OBJECTIVES

The aim of this study was to identify the response of the cricopharyngeus muscle (CPM) to esophageal stimulation by intraluminal mechanical distension and intraluminal acid and bile perfusion.

METHODS

In 3 adult pigs, electromyographic (EMG) activity of the CPM was recorded at baseline and after esophageal stimulation at 3 levels: proximal, middle, and distal. The esophagus was stimulated with 20-mL balloon distension and intraluminal perfusion of 40 mL 0.1N hydrochloric acid, taurocholic acid (pH 1.5), and chenodeoxycholic acid (pH 7.4) at the rate of 40 mL/min. The EMG spike density was defined as peak-to-peak spikes greater than 10 microV averaged over 10-ms intervals.

RESULTS

In all 3 animals, the spike density at baseline was 0. The spike densities increased after proximal and middle distensions to 15.2 +/- 1.5 and 5.1 +/- 1.2 spikes per 10 ms, respectively. No change in CPM EMG activity occurred after distal distension. The spike density following intraluminal perfusion with hydrochloric acid at the distal level was 10.1 +/- 1.1 spikes per 10 ms. No significant change in CPM EMG activity occurred after acid perfusion at the middle and proximal levels. No change in CPM EMG activity occurred after intraluminal esophageal perfusion with either taurocholic acid or chenodeoxycholic acid.

CONCLUSIONS

Proximal esophageal distension, as well as distal intraluminal acid perfusion, appeared to be important mechanisms in generation of CPM activity. Bile acids, on the other hand, failed to evoke such CPM activity. The data suggest that transpyloric refluxate may not be significant enough to evoke the CPM protective sphincteric function, thereby placing supraesophageal structures at risk of bile injury.

Long-term follow-up after anti-reflux surgery in patients with Barrett's esophagus

BACKGROUND

Factors associated with the risk of progression of Barrett's esophagus remain unclear, and the impact of therapy on this risk remains uncertain. The aim of this study was to assess patients followed long-term after anti-reflux surgery for Barrett's esophagus.

METHODS

A retrospective review was performed of all patients with Barrett's who underwent anti-reflux surgery from 1989 to 2009 and had ≥5 years of follow-up.

RESULTS

There were 303 patients and 75 had follow-up ≥5 years. Median follow-up time for the 75 patients was 8.9 years (range 5-18). Regression was seen in 31%. Progression occurred in 8%, and these patients were significantly more likely to have a failed fundoplication (67% vs. 16%, p = 0.0129). The rate of progression from non-dysplastic Barrett's to high-grade dysplasia or cancer was 0.8% per patient year, and was seven times higher in patients with a failed fundoplication.

CONCLUSION

Compared to the accepted rate of progression of non-dysplastic Barrett's to high-grade dysplasia or cancer of 1.0% per patient year, anti-reflux surgery reduces this rate during long-term follow-up. The rate of progression was significantly lower in patients with an intact compared to a disrupted fundoplication, further suggesting that anti-reflux surgery can alter the natural history of Barrett's esophagus.

Pathophysiology and treatment of Barrett’s esophagus

Gastroesophageal reflux disease (GERD) affects an estimated 20% of the population in the United States. About 10%-15% of patients with GERD develop Barrett’s esophagus, which can progress to adenocarcinoma, currently the most prevalent type of esophageal cancer. The esophagus is normally lined by squamous mucosa, therefore, it is clear that for adenocarcinoma to develop, there must be a sequence of events that result in transformation of the normal squamous mucosa into columnar epithelium. This sequence begins with gastroesophageal reflux, and with continued injury metaplastic columnar epithelium develops. This article reviews the pathophysiology of Barrett’s esophagus and implications for its treatment. The effect of medical and surgical therapy of Barrett’s esophagus is compared.

Bile acids identified in middle ear effusions of children with otitis media with effusion

OBJECTIVES/HYPOTHESIS

Several studies have shown the presence of pepsin in the middle ear effusions of children with otitis media with effusion (OME). When gastric reflux is the cause, other noxious reflux products might be present. We therefore investigated the presence of bile acids in the middle ear effusions of children with OME.

STUDY DESIGN

We evaluated 38 children (63 samples of middle ear secretions (ME samples)) in a prospective study at a tertiary care children's hospital.

METHODS

ME samples were collected from children with OME during ventilation tube insertion. Most ME samples were diluted with albumin. The presence of bile acids was measured with the 3alpha-hydroxy steroid dehydrogenase enzymatic method. A ME sample was considered positive when it contained at least 5 mumol/l bile acids, independent of dilution. Blood samples were taken simultaneously as a reference to determine bile acids serum levels.

RESULTS

We found bile acids in 32 % (20/63) of all ME samples and in 42% (16/38) of all children. Bile acids concentrations of 12 well-soluble ME samples ranged from 5.9-40.9 mumol/L and were 3.1-19.7 times higher than the serum concentrations. In 4 of the corresponding serums, no bile acids were measurable at all.

CONCLUSIONS

Bile acids are present in a number of the ME samples of children with OME. Because of dilution, it is possible that more ears contain bile acids. Bile acids are known to be noxious to mucosal cells at a higher (pH) than pepsin and, therefore, might play a role in the pathology of OME.

Do acid and bile reflux into the esophagus simultaneously? Temporal relationship between duodenogastro-esophageal reflux and esophageal pH

BACKGROUND

Duodenogastro-esophageal reflux (DGER) is an important factor in the pathogenesis of reflux esophagitis. Animal studies have demonstrated that the injurious effect of duodenal juice components depends on pH. The purpose of the present study was to investigate the temporal relationship between DGER and esophageal pH.

METHODS

Seventy-six children with symptoms of gastro-esophageal reflux disease (27 without, 31 with mild, 18 with severe esophagitis) underwent 24 h simultaneous esophageal pH and bilirubin monitoring with Bilitec 2000. The recordings were analyzed for (i) pH at the beginning of DGER episodes; (ii) relative duration of DGER in eight defined pH intervals of 1 pH unit; and (iii) differences in relative duration of DGER between the three groups of children.

RESULTS

DGER episodes most frequently began at pH between 6 and 7. DGER was present in the esophagus across the spectrum of esophageal pH, with the biggest relative duration between pH 3 and 5. However, in children without esophagitis relative duration of DGER was longest between pH 5 and 6, in children with mild esophagitis between pH 4 and 5, while in those with severe esophagitis it was between pH 2 and 4 (P < 0.001).

CONCLUSIONS

DGER appears across the whole esophageal pH spectrum. The more severe the esophagitis, the lower the pH at which DGER occurs, resulting in simultaneous damaging effects of acid and duodenal juice components.

The impact of reflux composition on mucosal injury and esophageal function

The components of refluxed gastric juice are known to cause mucosal injury, but their effect on esophageal function is less appreciated. Our aim was to determine the effect of acid and/or bile on mucosal injury and esophageal function. From 1993-2004, 402 patients with reflux symptoms had 24-hour pH and Bilitec monitoring, manometry, and endoscopy with biopsies. Mucosal injury (esophagitis or Barrett's esophagus) and esophageal function (lower esophageal sphincter [LES] characteristics and body contractility) in patients with acid reflux, bile reflux, or both were compared with patients without reflux. Reflux was present in 273/402 patients; of these, 37 (13.5%) had increased exposure to bile, 82 (30.0%) had increased exposure to acid, and 154 (56.4%) had increased exposure to both. Mucosal injury was most common with increased mixed acid and bile exposure, followed by acid alone, and was uncommon with bile alone (P < 0.0001). Functional deterioration paralleled mucosal injury (P < 0.0001). Mixed acid and bile exposure was present in more than half of patients with reflux and was associated with the most severe mucosal injury and the greatest deterioration of esophageal function. This suggests that composition of gastric juice is the primary determinant of inflammatory mucosal injury and subsequent loss of esophageal function.

The calcium-binding domain of the stress protein SEP53 is required for survival in response to deoxycholic acid-mediated injury

Stress protein responses have evolved in part as a mechanism to protect cells from the toxic effects of environmental damaging agents. Oesophageal squamous epithelial cells have evolved an atypical stress response that results in the synthesis of a 53 kDa protein of undefined function named squamous epithelial-induced stress protein of 53 kDa (SEP53). Given the role of deoxycholic acid (DCA) as a potential damaging agent in squamous epithelium, we developed assays measuring the effects of DCA on SEP53-mediated responses to damage. To achieve this, we cloned the human SEP53 gene, developed a panel of monoclonal antibodies to the protein, and showed that SEP53 expression is predominantly confined to squamous epithelium. Clonogenic assays were used to show that SEP53 can function as a survival factor in mammalian cell lines, can attenuate DCA-induced apoptotic cell death, and can attenuate DCA-mediated increases in intracellular free calcium. Deletion of the highly conserved EF-hand calcium-binding domain in SEP53 neutralizes the colony survival activity of the protein, neutralizes the protective effects of SEP53 after DCA exposure, and permits calcium elevation in response to DCA challenge. These data indicate that the squamous cell-stress protein SEP53 can function as a modifier of the DCA-mediated calcium influx and identify a novel survival pathway whose study may shed light on mechanisms relating to squamous cell injury and associated cancer development.

Bile acids aided by acid suppression therapy may be associated with the development of esophageal cancers in westernized societies

It was postulated that bile acids can interact with esophageal epithelia of rats, either by the gastro-duodeno-esophageal anastomosis operation, or by adding bile concentrate to the diet. These interactions would cause reflux diseases and eventually esophageal cancer. Rats gastrectomized and jejunostomized to allow bile acids to reflux into the esophagus developed many carcinomas in 50 weeks, while other modifications that kept bile out of the esophagus did not produce any carcinogenesis, thus supporting the hypothesis. Therefore, we conclude that bile acids refluxing into the esophagus of humans should also cause cancers, especially in Westernized societies with their high fat diets, which provide an abundant supply of bile. Bile acids can enter the model OE33 cells and activate the oncogene c-myc at pH 4, the gene complex NF-kappaB at pH 6.5, and start proliferation at neutral pH. 50% of Barrett's metaplasia contained activated c-myc, and 40% of Barrett's Esophagus patients contain activated NF-kappaB. Since normal human esophageal epithelia contained neither activated c-myc nor NF-kappaB, these activations must also occur in Barrett's patients. Acid suppression therapy is used to treat these patients, and will solubilize free bile acids and some of the glycine conjugates, allowing them to enter the epithelia. Taurine conjugates (20% of bile) will also enter the epithelia unaffected by acid suppression therapy. All these internalized bile acids will start carcinogenesis. Therefore, techniques to keep bile acids out of the stomach, or prevent them from reacting, must be developed, but until then, acid suppression therapy should be restricted, not promoted.

Bile reflux in the constellation of gastroesophageal reflux disease

Gastric acid and bile acids are a particularly noxious combination when they interact with the mucosa of the upper intestinal tract. There is a critical pH range, between 3 and 6, in which bile acids exist in their soluble, un-ionized form, can penetrate cell membranes, and accumulate within mucosal cells. At a lower pH, bile acids are precipitated, and at a higher pH, bile acids exist in their noninjurious ionized form. Experimental, clinical, and immunohistochemical studies show that acid and bile reflux are increased in patients who suffer from GERD, are the key factor in the pathogenesis of Barrett's esophagus, and possibly are related to the development of esophageal adenocarcinoma.

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.

Pathogenesis of reflux esophagitis and Barrett's esophagus

An understanding of the pathogenesis of reflux esophagitis and Barrett's esophagus requires knowledge of the noxious elements in gastric juice and the three major esophageal defenses designed to protect against them. When the esophageal epithelium cannot prevent gastric acid from acidifying the intercellular spaces, the foundation is set for the development of the major symptoms, signs, and complications of reflux esophagitis. Inadequate defense by the epithelium can occur by exposure to the acidic refluxate for a prolonged period of time, because of defects in the antireflux or luminal clearance mechanisms, or by exposure to ingested products that directly impair the epithelium's intrinsic defenses, rendering it vulnerable to injury from even physiologic levels of acid reflux.

Pathogenesis of Gastroesophageal Reflux Disease

The pathophysiology of reflux esophagitis involves contact of the esophageal epithelium with acid-pepsin in the refluxate. For this contact to occur with sufficient duration, there must either be a combination of defects in antireflux and luminal clearance mechanisms for acid-pepsin to overwhelm a previously healthy epithelium or primary defects within the epithelium develop that subsequently enable 'normal' acid contact times to become damaging to the epithelium. This report examines these 2 pathways to reflux esophagitis and questions the causative role attributed to some phenomena. In either case, the final common pathway for the clinical expression of reflux esophagitis is by damage to the esophageal epithelium that is responsible for the development of heartburn and/or esophageal necrosis and inflammation.

Bile in the esophagus: a factor in the pathogenesis of reflux esophagitis in children

OBJECTIVES

Bile reflux has been postulated to be an important factor contributing to gastroesophageal reflux disease in adults. The purpose of this study was to investigate its role in children.

METHODS

Sixty-five children with symptoms of gastroesophageal reflux disease were classified on the basis of the endoscopic grade of reflux esophagitis: no esophagitis (n = 26), mild to moderate esophagitis (n = 26), and severe esophagitis (n = 13). Simultaneous 24-hour esophageal pH and bilirubin monitoring with Bilitec 2000 was performed.

RESULTS

Both bile and acid reflux increased with the severity of esophagitis. The differences between all groups were significant for the percentage of total (P < 0.0005), upright (P < 0.05), and supine time (P < 0.0005) bilirubin absorbance > or = 0.14, as well as for the percentage of total and supine time pH < 4, and DeMeester score (P < 0.0005). Combined pathologic acid and bile reflux was found in 11% of children with mild esophagitis and in 70% of children with severe esophagitis, while isolated bile reflux was found in 31% and 7.5%, respectively. Combined pH and bilirubin monitoring, compared with ph-monitoring alone, increased the sensitivity from 56% to 79%, and the accuracy from 69% to 83%.

CONCLUSIONS

Both bile and acid reflux increase stepwise with the severity of esophagitis. Combined acid and bile reflux is associated with severe esophagitis. Isolated acid or bile reflux is usually present in mild esophagitis. Simultaneous esophageal pH and bilirubin monitoring has a higher sensitivity, as well as predictive values and accuracy than ph monitoring alone.

Pathogenesis of gastroesophageal reflux disease

The pathophysiology of GERD involves contact of the esophageal epithelium with acid/pepsin in the refluxate. For this contact to occur with sufficient duration, there must be a combination of defects in antireflux and luminal clearance mechanisms for acid/pepsin to overwhelm an intact epithelium, or defects within the epithelium develop that subsequently enable normal acid contact times to become damaging to the epithelium. In either case, the final common pathway is damage to the esophageal epithelium--damage that is reflected in the development of heartburn, esophageal necrosis and inflammation, or both.

Three hypotheses linking bile to carcinogenesis in the gastrointestinal tract: certain bile salts have properties that may be used to complement chemotherapy

The literature for the proliferative effect of bile acids on the GI tract has been reviewed and three hypotheses developed regarding their carcinogenicity. Considered as a unit, the GI tract is protected from this carcinogenicity in different ways in the esophagus, stomach, small bowel and colon. Uncharged BAs can enter the esophageal epithelial cells by reflux of gastroduodenal juices in humans, and in animals by surgical alteration of the GI tract or by adding bile concentrate to the diets, and this can initiate GERD and eventually cancer. Acid suppressant therapy used to treat GERD patients, converts stomach pH to >4. This will remove the charges on conjugated bile acids allowing them entry into the epithelium thus casting doubt on the efficacy of acid suppression. From these observations, we postulate that (a) uncharged BA in daily contact with the esophagus can cause GERD and eventually cancer. This might explain the cancers obtained by Fein et al. (b) Clinical trials designed to test the effectiveness of acid suppressants will be meaningless since up to approximately 87% of these patients (in one study) have bile in their refluxate, and this, combined with acid suppressants, will initiate carcinogenesis. (c) Bile reaching a colon made sterile by antibiotics or other means, will not be deconjugated and so, with pKa's of 2 and 4, will be uncharged and therefore can easily enter the colonic cells where the pH is >6. This should be of some concern, especially on a high-fat diet when more bile enters the colon. A group of physicians noted that approximately 47% of patients with esophageal cancers also had some form of colon cancer and postulated that an etiological factor in the environment was responsible. Could this factor be bile? Reactions of certain bile salts with epithelial cells suggest a useful role for them in chemotherapy. Experiments to test hypotheses a, b and c are presented in the addendum.

Role of acid and bile in the genesis of Barrett's esophagus

Clinical and experimental studies have shown that acid and bile reflux are increased in patients who have Barrett's esophagus. The combination of both seems the key factor in the pathogenesis of Barrett's esophagus. This factor has been confirmed by immunohistochemical studies that show that environmental factors, such as acid and bile, are involved in the pathogenesis of Barrett's esophagus. There is a critical pH range between 3 and 6 in which bile acids exist in their soluble, un-ionized form; can penetrate cell membranes; and accumulate within mucosal cells. At a lower pH, bile acids are precipitated, and at a higher pH, bile acids exist in their noninjurious ionized form. Thus incomplete gastric acid suppression, as is the case with most medical treatment regimens for gastroesophageal reflux, may in fact predispose to the development of Barrett's esophagus.

Review article: the role of non-acid reflux in gastro-oesophageal reflux disease

The role of acid in the pathogenesis of gastro-oesophageal reflux disease (GERD) has been extensively studied and is well accepted. The role, if any, of non-acid reflux, in particular duodenogastro-oesophageal reflux, is much debated. The availability of new technology to detect non-acid reflux has heightened interest in this question. This article reviews the following: How do we define non-acid reflux? Does duodenogastro-oesophageal reflux (alone or in combination) cause oesophageal injury, symptoms or both? What is its role in complicated GERD? What methods are available to assess non-acid reflux? Does non-acid reflux need treatment and if so what modalities are available?

Role of duodenal reflux in nonglandular gastric ulcer disease of the mature horse

Gastric contents were sampled in horses via nasogastric tube to determine changes in pH and bile salt concentrations during feeding and fasting periods. The horses were rotated through 4 feeding protocols. (1) hay; (2) hay with twice daily grain meals; (3) and (4) fasting preceded by either hay only or hay and grain. Sequential, hourly samples were collected from 3 horses prepared with gastric cannulas. Horses were fed hay twice daily and grain mix either twice daily or in small aliquots dispensed every 90 min. The horses were sampled during normal feeding or after 14 h of feed deprivation. Gastric pH values varied with time, but there was no significant difference between the feeding protocols or the fasting period on mean pH. Bile salt concentrations in fasted animals averaged 0.23-0.44 mmol/l with individual samples greater than 0.9 mmol/l. The bile salt concentrations in fed animals were consistently below 0.2 mmol/l. The effect of bile salt and acid on the stratified squamous gastric mucosa was tested in vitro. Mucosa, stripped of muscle and serosal layers, was mounted in Ussing chambers and the electrical potential difference (PD) across the tissue recorded. Sodium taurocholate or deoxycholate (0.3 mmol/l, bile salt) and/or HCl were added to the mucosal bathing solutions. The bile salt alone had no significant effect. Addition of acid (pH 2.5) to control tissues caused a decrease in the PD, which recovered within 20 min. Addition of acid to tissues exposed to bile salts resulted in a significant decrease in the PD, which did not recover. We conclude that combinations of bile salts and acid are more injurious to the stratified squamous gastric mucosa of the equine than acid alone. Concentrations of bile salts and acid sufficient to alter the electrolyte transport function of this mucosa can be found in the gastric contents of horses deprived of feed for as little as 14 h.

Biology of gastroesophageal reflux disease: pathophysiology relating to medical and surgical treatment

This chapter reviews the biology of gastroesophageal reflux disease, relating pathophysiology to medical and surgical therapy. Various definitions of the disease are presented and workable criteria are developed to identify patients with the disease. The central importance of the lower esophageal high-pressure zone as a barrier to reflux is emphasized, along with an analysis of its biomechanical alteration in disease. The composition of the refluxed gastric juice is characterized in regard to its potential for mucosal injury. Evidence is provided that cardiac-type mucosa is an acquired sequel to acid-induced squamous mucosal injury in the terminal esophagus. A hypothesis regarding the process of intestinalization of cardiac-type mucosa to form Barrett's esophagus is presented. An integrated concept of the pathophysiology of gastroesophageal reflux disease is constructed. Practical concepts regarding the treatment of gastroesophageal reflux disease are developed, based on a review of studies on the natural history of the disease and the long-term outcome of therapy.

Bile reflux in benign and malignant Barrett's esophagus: effect of medical acid suppression and nissen fundoplication

Bile reflux has been implicated in the pathogenesis and malignant degeneration of Barrett's esophagus, but clinical studies in patients with adenocarcinoma arising in Barrett's esophagus are lacking. Ambulatory esophageal measurement of acid and bile reflux was performed with the previously validated fiberoptic bilirubin monitoring system (Bilitec) combined with a pH probe in 20 asymptomatic volunteers, 19 patients with gastroesophageal reflux disease (GERD) but no mucosal injury, 45 patients with GERD and erosive esophagitis, 33 patients with GERD and Barrett's esophagus, and 14 patients with early adenocarcinoma arising in Barrett's esophagus. Repeat studies were done in 15 patients under medical acid suppression and 16 patients after laparoscopic Nissen fundoplication. The mean esophageal bile exposure time showed an exponential increase from GERD patients without esophagitis to those with erosive esophagitis and benign Barrett's esophagus and was highest in patients with early carcinoma in Barrett's esophagus (P <0.01). Pathologic esophageal bile exposure was documented in 18 (54.5%) of 33 patients with benign Barrett's esophagus and 11 (78.6%) of 14 patients with early adenocarcinoma in Barrett's esophagus. Nissen fundoplication but not medical acid suppression resulted in complete suppression of bile reflux. Bile reflux into the esophagus is particularly prevalent in patients with Barrett's esophagus and early cancer. Bile reflux into the esophagus can be completely suppressed by Nissen fundoplication but not medical acid suppression alone.

Composition and concentration of bile acid reflux into the esophagus of patients with gastroesophageal reflux disease

BACKGROUND

Reflux of duodenal contents into the esophagus of patients with gastroesophageal reflux disease has been suggested by pH and bilirubin monitoring but is rarely directly measured. A portable device has been developed and was used to collect and quantitate material refluxed into the esophagus under ambulatory conditions during a prolonged time period. The objective of this study was to use this device to quantitate the composition and concentration of bile acids refluxed into the esophagus of patients with gastroesophageal reflux disease.

METHODS

Esophageal aspiration was performed on 43 normal subjects and 37 patients with reflux disease during a 17-hour period. Aspiration was performed through a modified 16F Salem sump tube, positioned 5 cm above the lower esophageal sphincter and connected to a portable, battery powered pump that aspirated continuously at 100 mm Hg pressure. Validation studies showed that minimal amounts of saliva and swallowed liquids were aspirated and that gastric pressure was not altered. Postprandial, upright, and supine collections were performed. Total bile acids were assayed by a standard enzymatic assay; specific conjugated bile acids were analyzed by high-performance liquid chromatography.

RESULTS

There was no difference in the total aspiration volume between normal volunteers and patients with gastroesophageal reflux disease, although patients tended to have a higher volume in the supine and postprandial periods. Bile acids could be detected in 58% of normal subjects and 86% of patients (p < 0.003). The mean concentration of bile salt exposure (micromole per liter) was higher in patients during the postprandial and supine periods. The mean bile acid reflux rate (micromole per hour) during all three aspiration periods was significantly higher in patients. On a molar basis the composition of the bile acids was 60% glycocholic acid, 16% glycodeoxycholic acid, and 15% glycochenodeoxycholic acid. Taurocholic, taurodeoxycholic, taurochenodeoxycholic, and glycolithocholic acid constituted the remaining 10%.

CONCLUSIONS

Patients with reflux disease have an increased concentration of bile acids in their esophageal aspirates. Most of the exposure occurs during the postprandial and supine periods. A variety of bile acids were detected, most of which were in their glycine conjugated form.

Mixed reflux of gastric and duodenal juices is more harmful to the esophagus than gastric juice alone. The need for surgical therapy re-emphasized

OBJECTIVE

The author's goal was to determine the role of duodenal components in the development of complications of gastroesophageal reflux disease.

SUMMARY AND BACKGROUND DATA

There is a disturbing increase in the prevalence of complications, specifically the development of Barrett's esophagus among patients with gastroesophageal reflux disease. Earlier studies using pH monitoring and aspiration techniques have shown that increased esophageal exposure to fluid with a pH above 7, that is, of potential duodenal origin, may be an important factor in this phenomenon.

METHODS

The presence of duodenal content in the esophagus was studied in 53 patients with gastroesophageal reflux disease confirmed by 24-hour pH monitoring. A portable spectrophotometer (Bilitec 2000, Synectics, Inc.) with a fiberoptic probe was used to measure intraluminal bilirubin as a marker for duodenal juice in the esophagus. Normal values for bilirubin monitoring were established for 25 healthy subjects. In a subgroup of 22 patients, a custom-made program was used to correlate simultaneous pH and bilirubin absorbance readings.

RESULTS

Fifty-eight percent of patients were found to have increased esophageal exposure to gastric and duodenal juices. The degree of mucosal damage increased when duodenal juice was refluxed into the esophagus, in that patients with Barrett's metaplasia (n = 27) had a significantly higher prevalence of abnormal esophageal bilirubin exposure than did those with erosive esophagitis (n = 10) or with no injury (n = 16). They also had a greater esophageal bilirubin exposure compared with patients without Barrett's changes, with or without esophagitis. The correlation of pH and bilirubin monitoring showed that the majority (87%) of esophageal bilirubin exposure occurred when the pH of the esophagus was between 4 and 7.

CONCLUSIONS

Reflux of duodenal juice in gastroesophageal reflux disease is more common than pH studies alone would suggest. The combined reflux of gastric and duodenal juices causes severe esophageal mucosal damage. The vast majority of duodenal reflux occurs at a pH range of 4 to 7, at which bile acids, the major component of duodenal juice, are capable of damaging the esophageal mucosa.

Mixed reflux of gastric and duodenal juices is more harmful to the esophagus than gastric juice alone. The need for surgical therapy re-emphasized

OBJECTIVE

The author's goal was to determine the role of duodenal components in the development of complications of gastroesophageal reflux disease.

SUMMARY AND BACKGROUND DATA

There is a disturbing increase in the prevalence of complications, specifically the development of Barrett's esophagus among patients with gastroesophageal reflux disease. Earlier studies using pH monitoring and aspiration techniques have shown that increased esophageal exposure to fluid with a pH above 7, that is, of potential duodenal origin, may be an important factor in this phenomenon.

METHODS

The presence of duodenal content in the esophagus was studied in 53 patients with gastroesophageal reflux disease confirmed by 24-hour pH monitoring. A portable spectrophotometer (Bilitec 2000, Synectics, Inc.) with a fiberoptic probe was used to measure intraluminal bilirubin as a marker for duodenal juice in the esophagus. Normal values for bilirubin monitoring were established for 25 healthy subjects. In a subgroup of 22 patients, a custom-made program was used to correlate simultaneous pH and bilirubin absorbance readings.

RESULTS

Fifty-eight percent of patients were found to have increased esophageal exposure to gastric and duodenal juices. The degree of mucosal damage increased when duodenal juice was refluxed into the esophagus, in that patients with Barrett's metaplasia (n = 27) had a significantly higher prevalence of abnormal esophageal bilirubin exposure than did those with erosive esophagitis (n = 10) or with no injury (n = 16). They also had a greater esophageal bilirubin exposure compared with patients without Barrett's changes, with or without esophagitis. The correlation of pH and bilirubin monitoring showed that the majority (87%) of esophageal bilirubin exposure occurred when the pH of the esophagus was between 4 and 7.

CONCLUSIONS

Reflux of duodenal juice in gastroesophageal reflux disease is more common than pH studies alone would suggest. The combined reflux of gastric and duodenal juices causes severe esophageal mucosal damage. The vast majority of duodenal reflux occurs at a pH range of 4 to 7, at which bile acids, the major component of duodenal juice, are capable of damaging the esophageal mucosa.

Role of acid and duodenogastric reflux in esophageal mucosal injury: a review of animal and human studies

The role of acid and duodenogastric reflux (DGR) in the development of esophageal mucosal injury has been extensively investigated using both animal and human models. In this report, clinical and experimental data are reviewed. The mechanisms by which gastric and duodenal contents produce esophageal mucosal injury are also discussed. Acid and pepsin are unquestionably important in causing mucosal damage at low pH values in both animal and human models. Animal models suggest synergistic damaging potential for conjugated bile acids and HCI as well as that of unconjugated bile acids and trypsin in more neutral pH values. Human evidence for the involvement of bile and its constituents has been controversial; however, the advent of better technology to detect DGR is beginning to clarify the role of these constituents. The contribution of each methodology in clarifying the extent of involvement of DGR in esophageal mucosal injury is reviewed. Despite some conflicting results, preliminary human studies support the results from the animal data suggesting synergistic damaging effects for both bile and acid in esophageal mucosal injury. The implication of these studies in treating gastroesophageal reflux disease are discussed.

Bismuth subsalicylate reduces peptic injury of the oesophagus in rabbits

Bismuth subsalicylate was tested in an in vivo perfused rabbit model of oesophagitis for its ability to prevent the mucosal injury caused by pepsin. Treatment efficacy was assessed under both a treatment-before-injury protocol and a treatment-after-injury protocol. Oesophageal mucosal barrier function was evaluated by measuring flux rates of H+, K+, and glucose. The degree of oesophagitis was determined by gross and microscopic examination of the mucosa by several independent observers. Results showed that under both treatment protocols, bismuth subsalicylate significantly reduced the pepsin induced disruption of the mucosal barrier, as well as the morphologic changes. Bismuth subsalicylate when given after exposure to pepsin was also found to protect against the morphologic injury in a dose dependent manner. Experiments in vitro suggested that bismuth subsalicylate inhibits the proteolytic action of pepsin by interacting with pepsin, rather than with the pepsin substrate. We conclude that bismuth subsalicylate can protect the oesophageal mucosa against peptic injury, probably through inactivation of pepsin.