Mechanisms of oesophageal mucosal defence

Pathophysiology of Pediatric Gastroesophageal Reflux Disease: Similarities and Differences With Adults

Gastroesophageal reflux (GOR) is defined as "the passage of gastric contents into the esophagus with or without regurgitation and vomiting" and gastroesophageal reflux disease (GORD) is defined "when GOR leads to troublesome symptoms affecting the daily functioning and/or complications." This definition was first developed in 2006 by the Montreal consensus group (1) and later on adopted by pediatric gastroenterology societies such as ESPGHAN and NASPGHAN in 2009 (2). The definition of gastroesophageal reflux reveals little about its pathophysiology and is focused on symptomatology. In this way, it acts as an umbrella term for the multifactorial causes of the disease and the various phenotypes encountered; from functional heartburn to hypersensitive esophagus and nonerosive reflux disease, to erosive esophagitis and Barrett's esophagus. This article is devoted to the pathophysiology of pediatric GORD in comparison to adult GORD and is divided in 2 parts. In the first part, we will systematically describe the different mechanisms for the generation and clearance of reflux events, while on the second part we will discuss the mechanisms involved in symptoms generation. Finally, we will discuss the similarities and differences between pediatric and adult GORD.

Immune system and microbiome in the esophagus: implications for understanding inflammatory diseases

The gastrointestinal tract is the largest compartment of the body's immune system exposed to microorganisms, structural components and metabolites, antigens derived from the diet, and pathogens. Most studies have focused on immune responses in the stomach, the small intestine, and the colon, but the esophagus has remained an understudied anatomic immune segment. Here, we discuss the esophagus' anatomical and physiological distinctions that may account for inflammatory esophageal diseases.

The esophageal mucosal barrier in health and disease: mucosal pathophysiology and protective mechanisms

Diseases of the esophagus, such as gastroesophageal reflux (GER), can result in changes to mucosal integrity, neurological function, and the microbiome. Although poorly understood, both age and GER can lead to changes to the enteric nervous system. In addition, the esophagus has a distinct microbiome that can be altered in GER. Mucosal integrity is also at risk due to persistent damage from acid. Diagnostic tools, such as ambulatory pH/impedance testing and esophageal mucosal impedance, can assess short-term and longitudinal GER burden, which can also assess the risk for mucosal compromise. The quality of the mucosal barrier is determined by its intercellular spaces, tight junctions, and tight junction proteins, which are represented by claudins, occludins, and adhesion molecules. Fortunately, there are protective factors for mucosal integrity that are secreted by the esophageal submucosal mucous glands and within saliva that are augmented by mastication. These protective factors have potential as therapeutic targets for GER. In this article, we aim to review diagnostic tools used to predict mucosal integrity, aging, and microbiome changes to the esophagus and esophageal mucosal defense mechanisms.

Analysis of major bile acids in saliva samples of patients with Barrett's esophagus using high-performance liquid chromatography-electrospray ionization-mass spectrometry

A fast, non-invasive, high-performance liquid chromatographic screening method with electrospray ionization mass spectrometric detection was developed for the analysis of three major glycine-conjugated bile acids in human saliva. Using a mobile phase composed of 80% methanol and 0.1% formic acid, glycocholic, glycodeoxycholic, and glycochenodeoxycholic acids were separated in less than 4 minutes with sensitivity in the low nM range. Bile acids are thought to contribute to the pathology of various complications in gastroesophageal reflux disease, for instance, Barrett's esophagus, which may eventually lead to esophageal carcinoma. In this pilot study, samples of saliva obtained from 15 patients with Barrett's esophagus of various severities were compared to saliva samples from 10 healthy volunteers. Glycochenodeoxycholic acid was significantly elevated in the patients and principal component analysis of all bile acids could distinguish the most severe Barrett's esophagus patients. We also reported on the detection of glycochenodeoxycholic acid in exhaled breath condensate for the first time. The promising results of this pilot study warrant future investigation, aiming at non-invasive diagnostics of Barrett's esophagus susceptibility in patients with gastroesophageal reflux disease.

Differences in salivary secretory function between patients with erosive esophagitis and those with nonerosive reflux disease

BACKGROUND AND AIM

It has been speculated that impaired salivary flow contributes to abnormal acid clearance in patients with erosive esophagitis (EE). For easy and objective assessment of salivary function, we developed a salivary gland blood flow measurement technique using continuous-wave Doppler sonography. In the present study, we evaluated the salivary secretory function in patients with EE and those with nonerosive reflux disease (NERD) using this method.

METHODS

Doppler waveform analysis was performed on the facial artery to assess blood inflow to the submandibular gland of 30 healthy subjects (HS). Blood flow was compared before and after secretory stimulation with 1 mL of lemon juice. Saliva was simultaneously collected and weighed before and after stimulation. Continuous-wave Doppler sonography was also performed in patients with EE and NERD. The size of the submandibular gland was compared in 26 patients with EE, 41 patients with NERD, and 86 HS.

RESULTS

The submandibular gland blood flow increased after stimulation in all HS. Both within-day and day-to-day reproducibility were good. There was a significant correlation between the percent increase in the maximum velocity and the percent increase in salivary secretion. Although the size of the submandibular gland was not significantly different among the three groups, the percent increase in the maximum velocity in patients with EE was significantly smaller than that in HS.

CONCLUSIONS

We have established an easy method of assessing salivary function in daily practice. This study revealed that a decrease in salivary secretory function is involved in the pathology of EE.

Adam, Eve and the reflux enigma: age and sex differences across the gastro-oesophageal reflux spectrum

INTRODUCTION

We present demographic differences across the gastro-oesophageal reflux disease (GORD) spectrum in a UK District General Hospital.

PATIENTS AND METHODS

Data were prospectively collected over 37 years. At endoscopy patients were categorized as: erosive oesophagitis (EO), Barrett's oesophagus (BO) or nonerosive reflux disease (NER). Analysis 1: comparison of EO, BO and NER 1977-2001 when the database for GORD without BO closed. Analysis 2: demographic differences in oesophageal adenocarcinoma (OAC) in total BO population diagnosed 1977-2011.

RESULTS

GORD 1977-2001 (n=11 944): sex, male predominance in EO and BO but not NER; male : female ratios, 1.81, 1.65, 0.87, respectively (P<0.0001); mean age at presentation, EO 54 years, BO 62 years, NER 50 years; women were older than men by 10, 7 and 6 years, respectively.BO 1977-2011: prevalent OAC, 87/1468 (6%); male : female ratio, 4.1 (P<0.0001); incident OAC, 54/1381 (3.9%); male : female ratio, 3.5 (P<0.0001). Among all BO, more men developed OAC (3 vs. 0.9%). Within each sex, proportion of OAC higher among men (4.9 vs. 2.3%); at OAC diagnosis women were slightly but not significantly older (69.9 vs. 72.3 years, P=0.322).

CONCLUSION

Two views may explain our findings. First, women have either milder reflux, or reduced mucosal sensitivity hence reflux remains silent for longer. Alternatively, women genuinely develop reflux later, that is, are more protected and for longer from developing GORD and its complications. Early evidence is emerging that female sex hormones may indeed have a protective role in GORD during the reproductive period. We suggest reflux and its consequences may be an example of 'protection' conferred on Eve.

Simulation studies of the role of esophageal mucosa in bolus transport

Based on a fully coupled computational model for esophageal transport, we analyzed the role of the mucosa (including the submucosa) in esophageal bolus transport and how bolus transport is affected by mucosal stiffness. Two groups of studies were conducted using a computational model. In the first group, a base case that represents normal esophageal transport and two hypothetical cases were simulated: (1) esophageal mucosa replaced by muscle and (2) esophagus without mucosa. For the base case, the geometric configuration of the esophageal wall was examined and the mechanical role of mucosa was analyzed. For the hypothetical cases, the pressure field and transport features were examined. In the second group of studies, cases with mucosa of varying stiffness were simulated. Overall transport characteristics were examined, and both pressure and geometry were analyzed. Results show that a compliant mucosa helped accommodate the incoming bolus and lubricate the moving bolus. Bolus transport was marginally achieved without mucosa or with mucosa replaced by muscle. A stiff mucosa greatly impaired bolus transport due to the lowered esophageal distensibility and increased luminal pressure. We conclude that mucosa is essential for normal esophageal transport function. Mechanically stiffened mucosa reduces the distensibility of the esophagus by obstructing luminal opening and bolus transport. Mucosal stiffening may be relevant in diseases characterized by reduced esophageal distensibility, elevated intrabolus pressure, and/or hypertensive muscle contraction such as eosinophilic esophagitis and jackhammer esophagus.

Does the healing of the esophageal mucosa improve the function of the esophageal submucosal and salivary glands?

The esophageal pre-epithelial barrier encompasses components of secretions from both the esophageal submucosal and salivary glands. We demonstrated, in patients with reflux esophagitis (RE), significantly diminished luminal release of esophageal epidermal growth factor (EGF). The rate of luminal release of esophageal prostaglandin E₂ (PGE₂ ) was significantly higher compared with controls and significantly declined after healing of RE. Patients with RE also exhibited significant declines in esophageal mucin secretion; however, after healing of RE with rabeprazole, this rate increased significantly. The rate of salivary EGF and bicarbonate secretion in patients with RE was significantly lower than in controls. We have demonstrated that mastication of tasteless parafilm, which could be substituted with sugarless chewing gum in the clinical scenario, resulted in profound and significant increases in the rate of secretion of salivary protective factors, such as bicarbonate, mucin, protein, EGF, and PGE₂ , in patients with RE. Our data clearly indicate that there is a relationship between the form or the structure of the esophageal mucosa and the secretory function of not only the esophageal submucosal glands but also the salivary glands. Application of masticatory stimulation in a clinical scenario may also have some therapeutic potential.

The effects of baclofen for the treatment of gastroesophageal reflux disease: a meta-analysis of randomized controlled trials

Objectives. Baclofen can relieve gastroesophageal reflux-related symptoms in healthy subjects and gastroesophageal reflux disease (GERD) patients by reducing the incidence of transient lower esophageal sphincter relaxation. This meta-analysis aimed to evaluate the efficacy and safety of baclofen for the treatment of GERD. Methods. We systematically searched randomized controlled trials published prior to November 2013 from PubMed, Medline, Embase, ScienceDirect, ClinicalTrials.gov, and the Cochrane Central Register of Randomized Controlled Trials. We performed a meta-analysis of all eligible trials. Results. Nine studies were identified with a total of 283 GERD patients and healthy subjects. Comparative analysis provided high quality data supporting the ability of baclofen to promote a short-term decrease in the number of reflux episodes per patient, the average length of reflux episodes, and the incidence of transient lower esophageal sphincter relaxation. No serious adverse events or death events were reported, and there were no significant differences in the overall adverse events between baclofen and placebo. All reported side effects of baclofen were of mild-to-moderate intensity, and the drug was well tolerated. Conclusion. Abundant evidence suggests that baclofen may be a useful approach for the treatment of GERD patients; however, a larger well-designed research study would further confirm this recommendation.

Necrotizing sialometaplasia-like change of the esophageal submucosal glands is associated with Barrett's esophagus

The esophageal submucosal glands (SMG) protect the squamous epithelium from insults such as gastroesophageal reflux disease by secreting mucins and bicarbonate. We have observed metaplastic changes within the SMG acini that we have termed oncocytic glandular metaplasia (OGM), and necrotizing sialometaplasia-like change (NSMLC). The aim of this study is to evaluate the associated clinicopathological parameters of, and to phenotypically characterize the SMG metaplasias. Esophagectomy specimens were retrospectively assessed on hematoxylin and eosin sections and assigned to either a Barrett's esophagus (BE) or non-BE control group. Clinicopathologic data was collected, and univariate analysis and multivariate logistic regression models were performed to assess the adjusted associations with NSMLC and OGM. Selected cases of SMG metaplasia were characterized. SMG were present in 82 esophagi that met inclusion criteria. On univariate analysis, NSMLC was associated with BE (p = 0.002). There was no relationship between NSMLC and patient age, sex, tumor size, or treatment history. OGM was associated with BE (p = 0.031). No relationship was found between OGM and patient age, sex, or tumor size. On multivariate analysis, BE was independently associated with NSMLC (odds ratio [OR] 4.95, p = 0.003). Treatment history was also independently associated with OGM (p = 0.029), but not NSMLC. Both NSMLC and OGM were non-mucinous ductal type epithelia retaining a p63-smooth muscle actin co-positive myoepithelial cell layer. NSMLC and OGM were present in endoscopic mucosal resection specimens. Our study suggests that SMG metaplasia is primarily a reflux-induced pathology. NSMLC may pose diagnostic dilemmas in resection specimens or when only partially represented in mucosal biopsies or endoscopic resection specimens.

Pathophysiology of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is one of the most common digestive diseases in the Western world, with typical symptoms, such as heartburn, regurgitation, or retrosternal pain, reported by 15% to 20% of the general population. The pathophysiology of GERD is multifactorial. Our understanding of these factors has significantly improved in recent years, with increased understanding of the acid pocket and hiatal hernia and how these factors interact. Although our insight has significantly increased over the past years, more studies are required to better understand symptom generation in GERD, especially in patients with therapy-resistant symptoms.

Impairment of salivary mucin production resulting in declined salivary viscosity during naproxen administration as a potential link to upper alimentary tract mucosal injury

OBJECTIVES:

Nonsteroidal anti-inflammatory drugs (NSAIDs) contribute to the esophageal mucosal injury through its direct topical impact on the luminal aspect of the surface epithelium. Its indirect, systemic impact, however, on salivary component of the esophageal pre-epithelial barrier remains to be explored. Therefore, salivary mucin secretion and viscosity at baseline and during naproxen-placebo, as well as naproxen-rabeprazole, administration were investigated.

METHODS:

Twenty-one asymptomatic volunteers were included in this double-blind, placebo-controlled, crossover designed study. Salivary samples were obtained in basal and pentagastrin-stimulated conditions (6 mg/kg s.c.) mimicking the food-stimulated conditions. Patients received 7 days of naproxen-placebo or naproxen-rabeprazole with a 2-week washout period in between. Salivary mucin content and viscosity were measured before and after treatment using periodic acid/Schiff's methodology and Cone/Plate Digital Viscometer, respectively.

RESULTS:

The rate of salivary mucin secretion in basal condition declined by 32% during administration of naproxen-placebo (11.3±1.7 vs. 16.8±3.3 mg/h). Salivary mucin secretion in pentagastrin-stimulated condition declined significantly (by 34%) during the administration of naproxen-placebo (13.6±1.5 vs. 20.7±3.0 mg/h; P<0.05). Viscosity significantly decreased after naproxen-placebo administration in basal (by 60%) and stimulated conditions (by 56%) (P<0.001). Coadministration of rabeprazole at least partly restored the naproxen-induced decline of salivary mucin in basal condition (by 8%), and pentagastrin-stimulated conditions (by 30%).

CONCLUSIONS:

A significant decline of salivary mucin and viscosity during administration of naproxen may at least partly explain a propensity of patients on chronic therapy with NSAIDs to the development of esophageal mucosal injury and complications. In addition the trend to restorative capacity of rabeprazole on the quantitative impairment of salivary mucin during administration of naproxen may potentially translate into its tangible clinical benefit but it requires further investigation.

Pathophysiology of gastroesophageal reflux disease

The gastroesophageal junction is structurally complex and functionally designed to ensure the acid secreted by the most proximal gastric mucosa flows towards the stomach and not up onto the oesophageal squamous mucosa. The pattern and mechanism of reflux vary with the severity of reflux disease and this probably represents different ends of a spectrum rather than distinct pathophysiological mechanisms. Nearly all patients with severe reflux disease have hiatus hernia, however, a substantial proportion of patients with mild reflux disease do not, and this may be a result of intermittent or partial hiatus hernia undetectable by current available tools. The acid pocket is an area of post-prandial unbuffered gastric acidity immediately distal to the gastroesophageal junction and which is enlarged in patients with hiatus hernia. The acid pocket provides a reservoir of acid available to reflux when the intrinsic sphincter fails. Central obesity is an important factor in the aetiology of reflux and does this by the increased abdomino-thoracic pressure gradient inducing hiatus hernia and increasing the rate of flow of reflux when sphincter opens. Central obesity also induces short segment intrasphincteric reflux and thereby columnar metaplasia of the most distal oesophagus.

Relationship between baseline impedance levels and esophageal mucosal integrity in children with erosive and non-erosive reflux disease

BACKGROUND

Baseline impedance measurement has been reported to be related to esophageal acid exposure and hypothesized to be a marker of microscopic changes of the esophageal mucosa. Aims of the study were to establish whether any relationship existed between the magnitude of intercellular space diameter (ISD) of esophageal mucosa and baseline impedance levels in children with gastro-esophageal reflux disease (GERD), and to compare baseline impedance levels between children with non erosive (NERD) and erosive (ERD) reflux disease.

METHODS

Fifteen children (median age: 11.2 years) with NERD, and 11 with ERD (median age: 9.6 years) were prospectively studied. All patients underwent upper endoscopy. Biopsies were taken 2-3cm above the Z-line, and ISD was measured using transmission electron microscopy. All patients underwent impedance pH-monitoring, and baseline impedance levels were assessed in the most distal impedance channel.

KEY RESULTS

Mean (±SD) ISD did not differ between NERD (1.0±0.3μm) and ERD (1.1 ± 0.3 μm, ns). Considering all patients together, no correlation was found between distal baseline impedance and ISD (r: -0.15; ns). Conversely, negative correlations were found between distal baseline impedance and acid exposure time (r: -0.76; P<0.001), long-lasting reflux episodes (r: -0.78; P<0.001), acid reflux episodes (r: -0.62; P<0.001), and acid clearance time (r: -0.79; P<0.001). Distal baseline impedance was significantly lower in ERD [1455 (947-2338) Ω] than in NERD children [3065 (2253-3771) Ω; P<0.01].

CONCLUSIONS & INFERENCES

  In children with GERD baseline impedance levels are not useful in predicting reflux-induced ultrastructural changes in the esophageal mucosa, despite their ability to discriminate between NERD and ERD.

Oesophageal sensation in response to high PCO(2) and acidic solutions in nonerosive reflux disease

BACKGROUND

Heartburn is commonly associated with the presence of acid in the oesophageal lumen. However, in patients with nonerosive reflux disease (NERD), the mechanism by which acid traverses the mucosa is not clear. We hypothesized that the luminal acid signal traverses the oesophageal epithelium in the form of the highly permeant gas CO(2) , which then is reconverted to H(+) in the submucosa.

MATERIALS AND METHODS

  Ten patients with heartburn, normal upper endoscopy and increased oesophageal acid exposure (NERD patients) and 10 healthy subjects were enrolled. Perceptual responses to intraoesophageal acid (0·1 N HCl solution) and a high PCO(2) solution were determined using a randomized cross over design. Stimulus-response functions to perfusions were quantified by three parameters: lag time to symptom perception, intensity rating and perfusion sensitivity score.

RESULTS

 In NERD patients, the difference in lag time to typical symptom perception, intensity rating and perfusion sensitivity score between high PCO(2) and acid perfusions was statistically significant (P = 0·02, 0·01 and 0·02, respectively). However, the difference in the same perfusion parameters between acid and high PCO(2) perfusions was nonsignificant in healthy controls. When NERD and controls were compared, the difference between the different perfusion variables was nonsignificant (adjusted to age).

CONCLUSIONS

In NERD subjects, acid perfusion reliably evoked heartburn symptoms of greater intensity than in healthy controls. Nevertheless, a high PCO(2) perfusion failed to produce symptoms in either group.

Oral manifestations of gastroesophageal reflux disease

Numerous case-control and other studies involving confirmation of gastroesophageal reflux disease (GERD) by esophageal pH-metry and the assessment of dental erosions have shown significant associations between the two conditions in both adults and children. By contrast, when asked to vote on whether GERD may cause dental erosions, only 42% of physicians strongly agreed that such an association existed in adults, and just 12.5% strongly agreed for children, respectively in two global consensus reports. Part of this divergence between the perceptions of physicians and the findings of research publications may reflect a general lack of oral health education during medical training, and cursory oral examinations being made under less-than-ideal conditions. Adequate salivary secretions are essential for the protection of the teeth and the oropharyngeal and esophageal mucosa. The quantity and quality of the saliva require monitoring as many drugs, including several of the proton pump inhibitors (PPIs), can cause hyposalivation. In addition, PPIs do not always result in adequate acid suppression. Therefore, collaboration between physicians and dentists is strongly advocated to prevent or ameliorate possible adverse oral effects from both endogenous and exogenous acids, and to promote adequate saliva production in patients with GERD.

The role of mucin in GERD and its complications

Acid, pepsin and other noxious material reach the esophageal mucosa and interact with the luminal aspect of the squamous epithelium. The first protective barrier to these potentially injurious substances is the mucus buffer layer that covers the mucosa. In healthy people, the esophagus has a protective surface adherent mucus gel barrier. Levels of mucin glycoprotein are considerably increased in response to acid and pepsin. A wide spectrum of mucin genes are expressed in normal esophageal mucosa, squamous cell carcinoma of the esophagus, Barrett epithelium and esophageal adenocarcinoma. The mucins MUC5AC and MUC6 are expressed to a similar degree in Barrett metaplasia and gastric mucosa, as is MUC2 in Barrett intestinal metaplasia and small bowel mucosa. Increased expression of MUC1 is associated with progression from dysplasia to adenocarcinoma of the esophagus. Thus, mucins have an important role in the defense of esophageal mucosa against the acid, pepsin and bile that are present in the refluxate. Changes in the expression of mucins occur in patients with GERD, and might lead to the development of new drugs.

Advances in drug therapy for gastroesophageal reflux disease

The incidence of gastroesophageal reflux disease (GERD) is increasing drastically in China. GERD could probably cause reflux esophagitis, chronic cough, asthma, Barrett's esophagus and adenocarcinoma, and frequently affects health-related quality of life. The use of proton pump inhibitors (PPIs) provides effective symptomatic relief in most patients; however, some patients appear refractory to the treatment with PPIs. The long term use of PPIs might also cause adverse effects, such as interstitial nephritis, fracture and small intestinal bacterial overgrowth. Many new drugs for GERD have emerged recently. This article reviews the advances in drug therapy for GERD.

Significant increase of esophageal mucin secretion in patients with reflux esophagitis after healing with rabeprazole: its esophagoprotective potential

Esophageal mucin secretion in patients with reflux esophagitis (RE) is significantly impaired. Rabeprazole augments gastric mucin secretion. We have studied, therefore, the effect of rabeprazole on esophageal mucin secretion in patients with RE. The study was conducted in 15 patients with RE treated with rabeprazole (20 mg QD) for 8 weeks. Esophageal secretions were collected during consecutive infusions of initial NaCl, HCl/Pepsin (HCl/P), and a final NaCl, using a specially designed esophageal catheter, before and after therapy. Mucin was measured using standard methodology. After rabeprazole administration esophageal mucin concentration as well as secretion increased during perfusion with initial saline (P < 0.01), HCl/P (P < 0.02), and concluding saline (P < 0.001). Stimulation of esophageal mucin secretion by rabeprazole may indicate that the mechanisms governing its secretion are similar to those implicated in gastric mucin output. Enhancement of esophageal mucin secretion by rabeprazole may translate into esophagoprotective potential in patients with reflux esophagitis.

Association of erosive esophagitis with Helicobacter pylori eradication: a role of salivary bicarbonate and glycoprotein secretion

In some populations, Helicobacter pylori eradication is associated with development of erosive esophagitis. The aim of this study was to evaluate the contribution of salivary bicarbonate and glycoprotein secretion to the pathogenesis of erosive esophagitis developing after H. pylori eradication. Gastroscopy and saliva collection were performed at recruitment and 12 months after completion of eradication therapy. Eighty-eight patients with duodenal ulcer were recruited to the study. Erosive esophagitis was found in 13 patients (grade A, 8 patients; grade B, 4 patients; grade C, 1 patient). Among the 74 subjects who completed the study, erosive esophagitis was detected in 21 patients (grade A, 15 patients; grade B, 6 patients); they all were successfully eradicated. Bicarbonate and glycoprotein secretion was not found to differ significantly between the subjects with and without erosive esophagitis both before and 1 year after H. pylori eradication. However, it was lower in H. pylori-infected (baseline) than in H. pylori-noninfected erosive esophagitis subjects (1 year after successful eradication) (bicarbonate 2.34 [1.29-3.40)]vs. 3.64 [2.70-4.58]micromol/min and glycoprotein 0.23 [0.15-0.31]vs. 0.35 [0.28-0.43] mg/min, P= 0.04 and P= 0.04, respectively). We conclude that changes in salivary bicarbonate and glycoprotein secretion related to H. pylori eradication do not promote the development of erosive esophagitis in duodenal ulcer patients.

Saliva variations in gastro-oesophageal reflux disease

OBJECTIVES

The protective role of saliva in the case of oesophageal exposition to gastric acid has long been studied but some contradictions still remain. The main end-point of this study was to evaluate if a qualitative and quantitative alteration in salivary secretion exists in patients affected by GERD.

METHODS

One hundred and twenty patients (T group) with clinically and endoscopically diagnosed GERD, and 98 healthy subjects (C group) have been evaluated; salivary tests (i.e. basal flow rate, stimulated flow rate, pH, [Na(+)] and [K(+)]) were performed, socio-demographical variables and oral GERD-related symptoms were taken into account. SPSS 10.5 software was used for statistical univariate and multivariate analyses.

RESULTS

GERD patients and controls were found to have a similar basal flow rate but different stimulated salivary function [T group mean value 0.989 ml/min (+/-0.48718) vs. C group 1.2197 ml/min (+/-0.6108), pH [T group mean value 8.935 (+/-0.471) vs. C group 7.879 (+/-0.526)] and a higher K(+) concentration. In GERD patients we also registered a significant association with xerostomia [69/120 (57.5%) vs. 28/98 (28.7%)] and an oral burning sensation [58/120 (48.3%) vs. 19/98 (19.3%)].

CONCLUSIONS

Our findings assess that salivary secretion is altered in GERD patients and highlight the need for further investigations in order to define the role of saliva in the etiopathogenesis of GERD.

Review article: the pathophysiology of gastro-oesophageal reflux disease

BACKGROUND

Gastro-oesophageal reflux disease (GERD) is a common condition that develops when the reflux of stomach contents causes troublesome symptoms and/or complications.

AIM

To review the current knowledge on the underlying factors contributing to GERD, with particular emphasis on the most recent research.

METHODS

Literature searches were conducted in Medline and EMBASE. The abstracts from recent large congresses were also reviewed to ensure coverage of the latest findings.

RESULTS

The pathophysiological factors causing GERD can be split into those inducing greater exposure of the oesophagus to stomach contents, and those that provide increased perception of reflux or increased mucosal damage. Transient lower oesophageal sphincter relaxations, which are likely to be triggered by gastric distension, appear to be a key physiological cause of GERD. Excessive reflux may also be provoked by impaired oesophageal or gastric clearance mechanisms. Pre-epithelial, epithelial and post-epithelial defences all normally protect the oesophagus from injury, and may be compromised in individuals with GERD. Heartburn could also be caused by oesophageal hypersensitivity as a result of visceral neural pathway dysfunction.

CONCLUSION

The pathophysiology of GERD is multifactorial, and abnormalities in the gastro-oesophageal junction, the stomach, the oesophagus and the nervous system may all contribute to this disease state.

Normal values of [99mTc]pertechnetate uptake and excretion fraction by major salivary glands

The assessment of the functional status of the salivary glands has been used in the scintigraphic evaluation of xerostomia. Several quantitative methods derived from standard dynamic scintigraphy have been suggested. However, the indices proposed are quite variable and unlikely to be useful in clinical practice. The objectives of this study were to obtain reference values of major salivary glands uptake and excretion fraction in healthy subjects and to obtain normal ratios of Tc-pertechnetate uptake by the major salivary glands in comparison to the thyroid gland uptake. The standardization of these values has the purpose of making this evaluation faster and more objective. Fifty volunteers without clinical evidence of xerostomia or thyroid disease underwent static salivary glands scintigraphy with Tc-pertechnetate. Static images were obtained at 20 minutes and then at 3 minutes after oral stimulation with lemon juice. Percent uptake, excretion fraction and salivary gland to thyroid ratio rates were calculated for the parotid and the submandibular glands. The mean of the uptake values at 20 minutes for the right and left parotid glands were respectively 0.31% and 0.26%, and for the submandibular glands 0.15%. The excretion fraction of the tracer after the lemon juice stimulation was 70% for the parotids glands, 50% for the right and 49% for the left submandibular glands. The mean+/-SD salivary gland to thyroid count ratio was 0.79+/-0.45 for the right parotid, 0.78+/-0.5 for the left parotid, 0.67+/-0.33 and 0.66+/-0.34 for the right and left submandibular glands, respectively. Salivary glands scintigraphy with uptake and excretion fraction calculation is an easy to perform, non-invasive and objective method to investigate salivary glands function. These findings help the nuclear physician to interpret salivary gland scintigraphy more objectively, even in patients with thyroid gland dysfunction in whom Tc-pertechnetate thyroid uptake may be abnormal.

Age and sex distribution of the prevalence of Barrett's esophagus found in a primary referral endoscopy center

BACKGROUND

Both the demographics underlying the sex ratio in the prevalence of Barrett's esophagus (BE) and the status of BE without intestinal metaplasia (IM) are unclear.

AIMS

To establish the demographics of histologically proven BE, IM+ and IM-, over a 15-yr period from a primary referral, endoscopy unit.

PATIENTS AND METHODS

For all BE patients aged 20-89 yr, identified between 1982 and 1996, IM+ or IM-, prevalences were calculated per 100 first endoscopies.

RESULTS

A total of 492 cases of BE, 320 (248 IM+) in males, 175 (127 IM+) in females were identified in 21,899 first endoscopies (10,939 males, 10,960 females). Between ages 20 and 59 yr in males and 20-79 in females, IM+, IM- and all BE prevalences rose by +/-7.36% for each additional year of age (p= 0.92) with, however, a 20-yr age shift between the sexes, resulting in a male:female OR 4.15 95% CI 2.99-5.77. A declining rate of increase in over 59 males resulted in an overall male:female OR 2.14, 95% CI 1.77-2.58. Over the age of 79 yr, BE prevalences/100 first endoscopies fell from a maximum of 5.1 in males and 3.65 in females to 3.38 and 2.53, respectively.

CONCLUSION

The 4:1 sex ratio and 20-yr age shift between males and females in the prevalence of BE, both IM+ and IM-, found in younger age groups, was the main cause of the overall BE 2:1 sex ratio. The very similar demographics of IM- and IM+ BE suggest they may be two consecutive stages in the same metaplastic process.

Review article: new pharmacological agents for the treatment of gastro-oesophageal reflux disease

Proton pump inhibitors, which act at the terminal point of acid secretion--the H+, K+-ATPase--are currently the most effective pharmacological treatments available for reflux disease. Despite the efficacy of the proton pump inhibitors, there is still potential for clinical improvement in gastro-oesophageal reflux disease pharmacotherapy. Faster onset of complete acid inhibition and improved duration of efficacy are two potential areas for improvement A number of novel pharmaceutical agents are currently undergoing clinical evaluation for the treatment of gastro-oesophageal reflux disease. These include transient lower oesophageal sphincter relaxation-reducing agents, serotonergic agents/prokinetics, potassium-competitive acid blockers, mucosal protectants, histamine H3 agonists and anti-gastrin agents. One or more of these drug groups may represent the future medical therapy for gastro-oesophageal reflux disease, should they prove effective in the clinical setting. This review summarizes the state of the art with these agents.

The effect of mosapride on oesophageal motor function and acid reflux in patients with gastro-oesophageal reflux disease

OBJECTIVE

To evaluate the efficiency of the 5-HT4 agonist and 5-HT3 antagonist mosapride, as compared with cisapride, on oesophageal acid reflux variables and oesophageal motor function in patients with chronic gastro-oesophageal reflux disease (GORD).

METHOD

Forty-one patients with proven GORD were included in a double-blind, randomised, double-dummy, three-way crossover study. All patients received mosapride 60 mg twice daily, mosapride 30 mg three times daily, and cisapride 20 mg twice daily for seven days in a randomised order, separated by a washout period of at least five days. Twenty-three patients underwent four combined ambulatory 24-h motility and pH recordings within two weeks before the start of treatment and on day seven of each treatment period. The remaining 18 patients underwent three ambulatory 24-h pH recordings only, i.e. on treatment day seven of each treatment period.

RESULTS

Mosapride had no significant effect on the total number of contractions in the oesophagus, or on the effectiveness, or possible effectiveness, of the propagations. Significant but numerically small effects on peristaltic durations and amplitudes were noted during both mosapride and cisapride treatment as compared with baseline values. The effect on acid reflux for both mosapride and cisapride was most pronounced for the duration of the longest reflux episode. The fraction of time with pH less than 4 was reduced by mosapride 30 mg three times daily in the supine position and by cisapride both totally and in the supine position. The number of reflux episodes was reduced significantly only by cisapride. Oesophageal clearance was reduced significantly by cisapride only in the supine position.

CONCLUSION

Mosapride had small but statistically significant effects, comparable to those of cisapride, on acid reflux variables and oesophageal motor function in patients with GORD.

Adenocarcinoma in situ arising from the submucosal oesophageal mucous glands

The incidence of adenocarcinoma of the oesophagus is increasing; this type of carcinoma commonly arises on Barrett's oesophagus. We report a case of in-situ adenocarcinoma of the lower oesophagus arising in submucosal oesophageal mucous glands without intestinal metaplasia. We describe the histological findings, discuss the difficulties of differentiating this from invasive disease and review the current literature regarding this rare condition.

Effects of ABT-229, a motilin agonist, on acid reflux, oesophageal motility and gastric emptying in patients with gastro-oesophageal reflux disease

AIM

The effect of ABT-229, a new macrolide with no antibacterial activity, on gastro-oesophageal reflux, oesophageal motility and gastric emptying in patients with gastro-oesophageal reflux disease was investigated.

METHODS

Twenty-one patients were treated with a placebo and ABT-229 (2.5, 5 or 10 mg b.d.) in a randomized, incomplete crossover study design. Ambulatory 24-h pH manometry was performed and gastric emptying was assessed by the 13C-octanoic acid breath test on the seventh day of treatment.

RESULTS

A significant decrease was found in the mean (+/- s.e.) percentage of reflux time (intra-oesophageal pH < 4) for ABT-229 5 mg b.d. and 10 mg b.d., but not for 2.5 mg b.d., compared with placebo. For ABT-229 5 mg, it was 8.5 +/- 0.5% vs. 10.7 +/- 0.7% (P < 0.038) and, for ABT-229 10 mg, it was 6.6 +/- 0.5% vs. 8.4 +/- 0.5% (P < 0.019). There were no significant differences in any of the analysed manometric parameters. In addition, the gastric half-emptying time for all doses of ABT-229 did not differ significantly from that after placebo.

CONCLUSIONS

ABT-229 is able to reduce slightly, but significantly, acid reflux in patients with gastro-oesophageal reflux disease. This effect does not appear to be due to a measurable improvement in oesophageal motility or gastric emptying.

The significance of saliva during sleep and the relevance of oromotor movements

Saliva is an essential component of the oroesophageal milieu and allows for normal speech, taste, mastication, food bolus formation and swallowing. Saliva has important functions in protecting the hard and soft tissues of the oral cavity from acids and pathogenic microbes. A large number of people suffer either subjective or objective alterations in quantity and/or quality of their saliva that may be secondary to disease, medications, medical treatments or emotional events. Sleep-related xerostomia is a sensation of dry mouth associated with a report of either mouth and/or throat discomfort that induces awakenings for water intake. The prevalence of self-reported dry mouth complaint during sleep (associated with awakening and water intake) in a Canadian survey was estimated at 23%. The biological significance of decreased saliva during sleep is unknown and it is unclear how the oral cavity compensates for this period of relative dryness. The amount of saliva produced is greatest during the waking hours of the day and diminishes dramatically during sleep and may represent another process in the human body that displays a circadian rhythmicity. Salivary secretion during wakefulness is, in part, associated with oromotor activity involving the masticatory muscles. Rhythmic masticatory muscle activity and swallowing are non-disruptive events that occur during normal sleep. We hypothesize herein that lubrication from saliva is necessary during sleep to protect tissue integrity and health of oroesophageal structures.

Saliva and gastrointestinal functions of taste, mastication, swallowing and digestion

Saliva has multiple essential functions in relation to the digestive process taking place in the upper parts of the gastrointestinal (GI) tract. This paper reviews the role of human saliva and its compositional elements in relation to the GI functions of taste, mastication, bolus formation, enzymatic digestion, and swallowing. The indirect function of saliva in the digestive process that includes maintenance of an intact dentition and mucosa is also reviewed. Finally, pathophysiological considerations of salivary dysfunction in relation to some GI functions are considered.

The effect of cisapride on oesophageal motility and lower sphincter function in patients with gastro-oesophageal reflux disease

OBJECTIVES

To evaluate the efficiency by which the 5-HT4 agonist cisapride affects important motor functions involved in the control of gastro-oesophageal reflux.

METHOD

Thirty patients with proven gastro-oesophageal reflux disease (endoscopy and 24 h pH-metry) were included in a randomized, double-blind, placebo controlled study with a cross-over design. Cisapride, 20 mg b.i.d., during 4 weeks was compared with placebo. At baseline, as well as after 4 and 8 weeks all patients underwent symptom assessments, sleeve manometry with concomitant oesophageal pH-monitoring and an acid clearance test.

RESULTS

Despite adequate plasma levels cisapride had no significant effect on swallow induced peristaltic amplitude, duration, propagation speed, the elicitation of secondary peristalsis nor on acid clearance. Neither the basal tone of the lower oesophageal sphincter nor the number of transient lower oesophageal sphincter relaxations induced by gas distension of the stomach was affected by the administered dose of cisapride.

CONCLUSION

Although cisapride has been alleged to improve symptoms as well as the oesophagitis in patients with gastro-oesophageal reflux disease, we found the compound (20 mg b.i.d.) devoid of effects on important motor mechanisms involved in the pathogenesis of the disease.