Pathophysiological effects of long-term acid suppression in man

Qualitative analysis of anatomopathological changes of gastric mucosa due to long term therapy with proton pump inhibitors: experimental studies x clinical studies

INTRODUCTION

For a few decades the long-term use of proton pump inhibitors has had wide application in the treatment of several gastrointestinal diseases. Since then, however, several studies have called attention to the possible development of anatomical and pathological changes of gastric mucosa, resulting from the long term use of this therapeutic modality. Recent experimental and clinical studies suggest that these changes have connection not only to the development of precancerous lesions, but also of gastric tumors.

OBJECTIVE

To present a qualitative analysis of anatomical and pathological changes of gastric mucosa resulting from the long-term use of proton pump inhibitors.

METHOD

The headings used were: proton pump inhibitors, precancerous lesions and gastric neoplasms for a non systematic review of the literature, based on Medline, Lillacs and Scielo. Twelve articles were selected from clinical (9) and experimental (3) studies, for qualitative analysis of the results.

RESULTS

The gastric acid suppression by high doses of proton pump inhibitors induces hypergastrinemia and the consequent emergence of neuroendocrine tumors in animal models. Morphological changes most often found in these experimental studies were: enterochromaffin-like cell hyperplasia, neuroendocrine tumor, atrophy, metaplasia and adenocarcinoma. In the studies in humans, however, despite enterochromaffin-like cell hyperplasia, the other effects, neuroendocrine tumor and gastric atrophy, gastric metaplasia and or adenocarcinoma, were not identified.

CONCLUSION

Although it is not possible to say that the long-term treatment with proton pump inhibitors induces the appearance or accelerates the development of gastric cancer in humans, several authors have suggested that prolonged administration of this drug could provoke the development of gastric cancer. Thus, the evidence demonstrated in the animal model as well as the large number of patients who do or will do a long-term treatment with proton pump inhibitors, justifies the maintenance of this important line of research.

Gastric carcinoids (neuroendocrine neoplasms)

Gastric neuroendocrine neoplasms of the stomach can be divided into the usually well-differentiated, hypergastrinemia-dependent type I and II lesions and the more aggressively behaving gastrin-independent type III lesions. Studying menin and its complex interrelationship with gastrin may provide insight into tumor biology at the clinical level and in terms of basic cell biology (eg, the role of the epigenome in neuroendocrine cell proliferation), and lead to potential consideration of other targets that are known candidates for molecular-based therapies in other adenocarcinomas.

[Role of Helicobacter pylori infection in iron deficiency anemia]

Anemia induced by digestive diseases refers to anemia due to iron deficiency. Conventional gastrointestinal diagnostic workup fails to establish the cause of iron deficiency in about one third of patients. Abnormal iron absorption is increasingly recognized as an important cause of unexplained iron deficiency. The importance of coeliac disease as a possible cause of iron deficiency anemia refractory to oral iron treatment, without other manifestations of malabsorption syndrome, is increasingly being recognized. In addition, Helicobacter pylori (HP) has been implicated in several recent studies as a cause of iron deficiency anemia (IDA) refractory to oral iron treatment. Cure of previously refractory IDA by HP eradication provides strong evidence supporting a cause-and-effect relationship. In order to establish a cause-and-effect relationship between HP gastritis and IDA, prospective randomized studies comparing the effects of iron administration with or without H. pylorieradication are highly recommended.

Helicobacter pylori-induced damage to the gastric mucosa is not modulated by previous vagotomy or medical treatment of peptic ulcer disease: a comparative study of vagotomized patients, medically treated peptic ulcer patients and community control subjects

BACKGROUND

An increase in the prevalence of precancerous lesions and atrophic changes in the gastric mucosa has been reported as long-term consequences of vagotomy-induced acid suppression. This study was designed to describe the long-term changes in the gastric mucosa caused by vagotomy and Helicobacter pylori infection.

METHODS

Seventy-nine patients with vagotomized peptic ulcers, 70 nonoperated patients with peptic ulcers, and 85 matched community control subjects were randomly selected to participate in an upper endoscopic study. Biopsy specimens were taken from predestined locations of the gastric mucosa.

RESULTS

Mean follow-up time for the vagotomized patients was 17.3 (range, 6-28) years and 12.7 (range, 10-17) years for the medically treated peptic ulcer patients. In H. pylori-positive subjects, severe atrophic changes in the distal gastric mucosa (prepylorus and angulus) was found in 30% (95% confidence interval (CI), 19-43) of the vagotomized patients and in 43% (95% CI, 29-58) of medically treated patients with peptic ulcers, and in 32% (95% CI, 20-46) of the community control subjects. Severe intestinal metaplasia was not found more frequently in vagotomized peptic ulcer patients compared with medically treated patients with peptic ulcers (p = 0.5). The histological picture of the age-matched community control subjects did not differ significantly from the patients with peptic ulcers when corrected for presence of H. pylori infection.

CONCLUSIONS

This study lends no support to theories of increased premalignant changes in the gastric mucosa of vagotomized patients. H. pylori infection rather than long-term acid suppression seems to be the explanation of the gastric mucosal changes seen after vagotomy.

Chronic hypergastrinemia: causes and consequences

The hormone gastrin plays 2 important roles in gastrointestinal physiology--1 as a major factor in meal-stimulated gastric acid secretion and the other as a trophic hormone for epithelial and enterochromaffin cells. These roles are exaggerated to the point of pathology under conditions of chronic hypergastrinemia as exemplified by the Zollinger-Ellison syndrome and pernicious anemia. More recently, the concern about the potential risk of chronic hypergastrinemia has risen because of the widespread use of proton pump inhibitors for maintenance therapy in reflux esophagitis. For this reason, we present a concise overview of the origin, causes, and potential risks of chronic hypergastrinemia.

Systematic review: the application of molecular pathogenesis to prevention and treatment of oesophageal adenocarcinoma

BACKGROUND

Oesophageal adenocarcinoma is an increasingly common cancer with a poor prognosis. It develops in a stepwise progression from Barrett's metaplasia to dysplasia, and then adenocarcinoma followed by metastasis.

AIM

To outline the key molecular changes in oesophageal adenocarcinoma and to summarize the chemopreventative and therapeutic strategies proposed.

METHODS

A literature search was performed to identify appropriate research papers in the field. Search terms included: Barrett's (o)esophagus, intestinal metaplasia, (o)esophageal adenocarcinoma, molecular changes, genetic changes, pathogenesis, chemoprevention, therapeutic strategies and treatment. The search was restricted to English language articles.

RESULTS

A large number of molecular changes have been identified in the progression from Barrett's oesophagus to oesophageal adenocarcinoma although there does not appear to be an obligate order of events. Potential chemoprevention strategies include acid suppression, anti-inflammatory agents and antioxidants. In established adenocarcinoma, targeted treatments under evaluation include receptor tyrosine kinase inhibitors of EGFR and cyclin-dependent kinase inhibitors, which may benefit a subgroup of patients.

CONCLUSIONS

Advances in molecular methodology have led to a greater understanding of the oesophageal adenocarcinoma pathways, which provides opportunities for chemoprevention and therapeutic strategies with a mechanistic basis. More work is required to assess both the safety and efficacy of these new treatments.

Long-term prevention of erosive or ulcerative gastro-oesophageal reflux disease relapse with rabeprazole 10 or 20 mg vs. placebo: results of a 5-year study in the United States

BACKGROUND

Erosive gastro-oesophageal reflux disease (GERD) is a chronic condition requiring long-term maintenance treatment. However, few trials of proton pump inhibitors in maintaining healing of erosive or ulcerative GERD are conducted for longer than 1 year.

AIM

To compare the efficacy and safety of 10- and 20-mg rabeprazole with placebo in the 5-year maintenance of healing in patients previously diagnosed with erosive/ulcerative GERD healed in an acute efficacy trial.

METHODS

Patients (N = 497) were randomized to receive once-daily doses of 10- or 20-mg rabeprazole or placebo. The primary efficacy measure was endoscopically documented absence of oesophageal erosions or ulcerations.

RESULTS

After 5 years, relapse rates in both rabeprazole groups were significantly lower than with placebo (rabeprazole 20 mg, 11%; 10 mg, 23%; placebo, 63%; P < 0.001 for rabeprazole vs. placebo; P = 0.005 for rabeprazole 20 mg vs. 10 mg). Both rabeprazole doses were significantly superior to placebo in preventing relapse of heartburn frequency and improving patient quality of life. Analyses of adverse events, biopsy findings and laboratory values showed no evidence of clinically significant effects.

CONCLUSIONS

Five-year maintenance therapy with rabeprazole is effective in preventing relapse of erosive or ulcerative GERD and is well tolerated.

The pathogenesis of gastrointestinal bacterial overgrowth

The normal indigenous intestinal microflora consists of about 10(15) bacteria that under physiological conditions reside mainly in the lower gastrointestinal tract. Bacterial overgrowth implies abnormal bacterial colonization of the upper gut, resulting from failure of specific defense mechanisms restricting colonization under physiological conditions. At present two types of bacterial overgrowth with defined pathogenesis can be distinguished: (1) gastric overgrowth with upper respiratory tract microflora resulting from selective failure of the gastric acid barrier, and (2) gastrointestinal overgrowth with Gram-negative bacilli (enteric bacteria) resulting from failure of intestinal clearance. Helicobacter pylori-induced gastritis of the oxyntic mucosa is the main cause of acquired failure of the gastric acid barrier, which is common among the healthy elderly. Intestinal clearance may fail as the result of impaired intestinal peristalsis or anatomical abnormalities that alter luminal flow. Impaired peristalsis is associated with conditions interfering with intestinal neuromuscular function including myopathic, neuropathic, autoimmune, infectious, inflammatory, metabolic, endocrine, and neoplastic diseases. Anatomical abnormalities are mainly the result of gastrointestinal surgery, intestinal diverticula or fistula. Combined failure of intestinal clearance and the gastric acid barrier results in more severe colonization with Gram-negative bacilli. Gram-negative bacilli are uncommon in the upper gut of otherwise healthy individuals with gastric hypochlorhydria, being acquired (H. pylori) or drug-induced. Significant bacterial overgrowth with Gram-negative bacilli is a rational in the search for an explanation to optimize clinical management. The clinical significance of colonization with upper respiratory tract microflora remains unclear. Translocation of live bacteria, their metabolic products, or antigens from a small bowel colonized by Gram-negative bacilli play a role in the pathogenesis of spontaneous bacterial peritonitis in hepatic disease and in certain types of sepsis, indicating that further studies can point to new patient populations with potential benefit from medical treatment.

Effects of 5 years of treatment with rabeprazole or omeprazole on the gastric mucosa

BACKGROUND

Prolonged gastric acid suppression leads to hypergastrinaemia, which promotes hyperplasia of the enterochromaffin-like (ECL) cells of the oxyntic mucosa. The objective was to determine the effects of 5 years of treatment with rabeprazole or omeprazole on the gastric mucosa.

METHODS

Two hundred and forty-three patients received rabeprazole (20 mg or 10 mg) or omeprazole (20 mg) once daily for up to 5 years, for gastro-oesophageal reflux disease and 51% completed the whole 5 year period. Gastric biopsy specimens were taken and examined for gastritis, Helicobacter pylori infection, and ECL cell status.

FINDINGS

H. pylori infection in the gastric corpus was more common than in the antrum, and remained constant, whereas antral H. pylori infection became less common as the study progressed. H. pylori infection was a highly significant predictor of higher gastritis scores, which were similar among the three treatment groups. ECL cell hyperplasia occurred in a minority of patients, and was associated with serum gastrin concentrations. No ECL cell dysplasia or tumours were observed. There were no significant differences among the treatment groups in gastritis or ECL cell hyperplasia grades.

INTERPRETATION

This study has confirmed the link between ECL cell hyperplasia and elevated serum gastrin concentrations, but has found no evidence that this progresses to high grades of hyperplasia during 5 years of treatment with rabeprazole or omeprazole.

Gastrin-induced cyclooxygenase-2 expression in Barrett's carcinogenesis

PURPOSE

Cyclooxygenase (COX)-2 has been causally implicated in carcinogenesis. The evidence for increased COX-2 in the malignant progression of Barrett's esophagus is contradictory. We hypothesize that COX-2 expression may be causally affected by the gastrin status via the cholecystokinin 2 (CCK(2)) receptor.

EXPERIMENTAL DESIGN

COX-2 and prostaglandin E(2) expression were evaluated by Western blotting and enzyme-linked immune assay in samples of squamous esophagus, Barrett's esophagus with varying degrees of dysplasia to adenocarcinoma, and normal duodenum. Differentiation status was evaluated by histopathology and villin expression. A longitudinal case-control study compared COX-2 in patients who progressed to adenocarcinoma with nonprogressors matched for age and length of follow-up. Messenger RNA levels of gastrin and CCK(2) receptor in biopsies and cell lines were evaluated by reverse transcription-PCR, and in vitro gastrin stimulation was conducted with and without inhibitors for CCK(2) (YM022) and COX-2 (NS-398). Cell proliferation was evaluated using minichromosome maintenance protein 2 (Mcm2) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays.

RESULTS

COX-2 expression is significantly increased in Barrett's esophagus before dysplasia development. Expression is highly variable within Barrett's dysplasia and adenocarcinoma samples independent of differentiation status. In a longitudinal case-control study, the expression levels within patients increased over time, regardless of the degree of malignant progression. Biopsies from nondysplastic Barrett's esophagus expressed increased gastrin mRNA levels compared with other biopsies. Gastrin significantly induced COX-2, prostaglandin E(2), and cell proliferation in biopsies and cell lines. Gastrin-induced proliferation can be inhibited by YM022 and NS-398.

CONCLUSIONS

COX-2 is up-regulated early in the Barrett's metaplasia sequence. During carcinogenesis, gastrin is a significant determinant of COX-2 activity levels via the CCK(2) receptor.

A 50-year analysis of 562 gastric carcinoids: small tumor or larger problem?

OBJECTIVES

Interest in gastric carcinoid tumors has amplified considerably given the biological establishment of their relationship to gastrin and advances in the elucidation of the pathobiology of such lesions. The recognized propensity of acid-suppressing agents such as the proton pump inhibitor class of drugs to increase plasma gastrin levels has been proposed as a causal relationship in the apparent increase in the identification of such lesions although the increased prevalence of endoscopy and the enhanced awareness of pathologists have also been considered as contributory factors. We sought to examine if there has been an increase in gastric carcinoid incidence time correlative with these parameters.

METHODS

Carcinoid tumor cases from the End Results Group (1950-1969) and the Third National Cancer Survey (TNCS) (1969-1971) databases were combined with the most recent release of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry (1973-1999); these three datasets revealed 13715 carcinoid cases, of which 562 were gastric in origin. Age-adjusted analyses as well as population-based gender and race correction ratios were completed in conjunction with United States decennial census data. To allow a finer granularity in incidence trends, the SEER database was divided into early (1973-1991) and late (1991-1999) subsets. RESULTS Since 1950, the percentage of gastric carcinoids among all gastric malignancies has increased from 0.3% to 1.77%. Since 1969, the proportion of gastric carcinoids among all enteric carcinoid lesions has increased from 2.4% to 8.7%. Age-adjusted incidence rates among male, female, black, and white population subsets have all increased since the TNCS time period, with the greatest increase (800%) noted in white females. The male:female ratio has fallen from 0.90 to 0.54. The occurrence of synchronous or metachronous noncarcinoid tumors with gastric carcinoid tumors has decreased by 26% during the course of SEER data collection. The 5-yr survival rate for gastric carcinoids overall has risen from 51% to 63% during the same time period.

CONCLUSIONS

Gastric carcinoids have increased in incidence over the last 50 yr. Differential increases in predominance across gender and race subdivisions may reflect genetic-based propensities (or protection) for gastric carcinoid tumors among certain ethnic populations. Increased endoscopic surveillance and associated sophisticated pathological evaluation of gastric biopsies undoubtedly are responsible for some of the observed increase in the incidence of gastric carcinoid tumors. These data allow no specific role to be assigned to the effects of acid-suppressive medications. Nevertheless the role of such agents cannot be discounted at this time since the time frame of the increased incidence is somewhat comparable to the introduction of these agents as is the known biological effect of gastrin on ECL cell proliferation.

Malignant carcinoids in the USA, SEER 1992-1999. An epidemiological study with 6830 cases

Most of our knowledge on the epidemiology of carcinoid tumours in the USA relies on studies updated during the 1980s. The aim of this study was to describe USA population-based case-series incidence in the period 1992-1999. Data were retrieved from a Surveillance Epidemiology and End Results (SEER) Program public-use file. Incidence rates, male-to-female standardized ratios, estimated annual percentage changes and 5-year relative survival rates were computed, and 6830 malignant carcinoid incident during 1992-1999 were analysed. The overall age-adjusted incidence rates were 1.9 per 100 000 for men and women. There was an excess in women for lung and stomach carcinoids, while rates were higher among men for carcinoids of the small intestine and rectum. From 1992 to 1999, incidence rates showed a 3% estimated annual increase. Thirteen per cent of the cases had metastasis at diagnosis. In the present series, 24% of carcinoid patients had more than one tumour. The overall 5-year relative survival rate was 82%. In conclusion, improvements in diagnostic techniques seem to have influenced the epidemiology of carcinoid tumours, leading to a slightly different site distribution and a better stage distribution at diagnosis. Increasing incidence and improving survival rates were shown.

A 5-decade analysis of 13,715 carcinoid tumors

BACKGROUND

Carcinoid tumors represent an unusual and complex disease spectrum with protean clinical manifestations. This compilation of several large United States-based databases comprising patients from 1950 to 1999 examines 13,715 carcinoid tumors and provides epidemiologic information regarding the natural history and evolution of the detection and diagnosis of this entity.

METHODS

The authors evaluated 10,878 carcinoid tumors that were identified by the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute (NCI) from 1973 to 1999 in addition to 2837 carcinoid tumors that were registered previously by two earlier NCI programs. To the authors' knowledge, this represents the largest current epidemiology series addressing carcinoid tumors to date.

RESULTS

Specific trends in incidence for carcinoid tumors of certain sites were identified. Among the most recently collected subset of data, sites that demonstrated the greatest incidence of carcinoids were the gastrointestinal tract (67.5%) and the bronchopulmonary system (25.3%). Within the gastrointestinal tract, most carcinoid tumors occurred in the small intestine (41.8%), rectum (27.4%), and stomach (8.7%). For all sites, age-adjusted incidence rates were highest in black males (4.48 per 100,000 population per year). Associated noncarcinoid tumors were frequent in conjunction with small intestinal (29.0%), gastric (20.5%), colonic (20.0%), and appendiceal (18.2%) carcinoids. The highest percentages of nonlocalized lesions were noted for cecal (81.5-83.2%) and pancreatic (71.9-81.3%) carcinoids, whereas the highest percentage of localized disease was found among rectal (81.7%), gastric (67.5%), and bronchopulmonary (65.4%) carcinoids. The best 5-year survival rates were recorded for patients with rectal (88.3%), bronchopulmonary (73.5%), and appendiceal (71.0%) carcinoids; these tumors exhibited invasive growth or metastatic spread in 3.9%, 27.5%, and 38.8% of patients, respectively.

CONCLUSIONS

Carcinoids appear to have increased in overall incidence over the past 30 years; for some sites, this trend has been evident for nearly half a century. Recent marked increases in gastric and rectal carcinoids and a concomitant decrease in appendiceal carcinoid incidence may be due in part to varying rules of registration among the compiled databases examined in this report or to improvements in diagnostic technology; increased awareness of and about carcinoid tumors also may play a significant role. In 12.9% of all patients with carcinoid, distant metastases already were evident at the time of diagnosis; the overall 5-year survival rate for all carcinoid tumors, regardless of site, was 67.2%. These findings bring into question the widely promulgated relative benignity of carcinoid disease. Certain carcinoid tumors, such as those of the rectum, appear to be over-represented among the black and Asian populations within the United States, suggesting the role of genetics in the development of this intriguing disease.

Estudo histológico e computadorizado das áreas com células parietais e principais no estômago de ratos Wistar tratados com pantoprazol e "N-Nitroso-N-Methylurea"(NMU)

O uso prolongado dos inibidores da bomba de prótons tem sido considerado uma condição de risco para o desenvolvimento de gastrite atrófica e tumores gástricos. Objetivo: Estudar o efeito do uso de pantoprazol (PTZ) e carcinogênese pela "N-Nitroso-N-Methylurea" (NMU), por 15 semanas, sobre o estômago glandular de ratos Wistar, pela análise histológica e computadorizada das áreas com células parietais (AP), principais (AZ) e da mucosa não oxíntica (ANO), além do estudo das alterações histopatológicas identificadas. Métodos: Quarenta ratos Wistar machos foram distribuídos em 4 grupos: G1 (controle), G2 (NMU+PTZ), G3 (PTZ) e G4 (NMU). O pantoprazol foi administrado 2x/semana (14mg/kg de peso, i.p.) e a NMU oferecida, ad libitum, diluída na água de beber (100mig/ml). Após o estudo histológico AP, AZ e ANO foram determinadas por análise computadorizada das imagens dos estômagos, utilizando o programa "ImageJ 1.19z". Resultados: Mostraram redução da AP e aumento da ANO, em G2, G3 e G4 (p<0,001). Foram encontrados casos de atrofia, inflamação aguda e inflamação crônica, em número que impediu comparação estatística entre os grupos estudados. Conclusão: O uso contínuo de pantoprazol (i.p.), por 15 semanas, reduziu a área com células parietais e aumentou a área de mucosa não oxíntica no estômago glandular de ratos Wistar machos. O mesmo aconteceu no grupo de animais que receberam NMU isoladamente ou em associação com o pantoprazol.

Hypergastrinemia in response to gastric inflammation suppresses somatostatin

Hypergastrinemia and a reduction in tissue somatostatin occur in Helicobacter pylori-infected patients. We investigated whether the D cell may be a direct target of gastric inflammation and hypergastrinemia. D cells were quantified by morphometry and flow cytometry in 16-wk-old wild-type (G+/+) and gastrin-deficient (G-/-) mice. Hypochlorhydric G-/- mice were treated with either antibiotics for 20 days or infused with gastrin (G-17) for 14 days. G+/+ mice were made hypochlorhydric by treating them with omeprazole for 2 mo. G-/- mice showed significant inflammation compared with the G+/+ mice, which resolved after 20 days of antibiotic treatment. D cell numbers were not significantly different between G-/- and G+/+ mice. After G-17 was infused, fundic and antral D cell numbers decreased in the G-/- mice. G+/+ animals made hypergastrinemic with omeprazole exhibited decreased D cell numbers. When omeprazole-treated mice were treated with antibiotics alone, elevated plasma gastrin levels returned to baseline and D cell numbers returned to resting levels despite persistent hypochlorhydria. Hypergastrinemia, induced by inflammation, results in decreased D cell numbers. Thus the stomach responds to the presence of inflammation by reducing somatostatin levels, thereby releasing the inhibition on the G and parietal cells to maximize gastric acid output.

Gastrin, CCK, signaling, and cancer

Gastrin, produced by G cells in the gastric antrum, has been identified as the circulating hormone responsible for stimulation of acid secretion from the parietal cell. Gastrin also acts as a potent cell-growth factor that has been implicated in a variety of normal and abnormal biological processes including maintenance of the gastric mucosa, proliferation of enterochromaffin-like cells, and neoplastic transformation. Here, we review the models used to study the effects of gastrin on cell proliferation in vivo and in vitro with respect to mechanisms by which this hormone might influence normal and cancerous cell growth. Specifically, human and animal models of hypergastrinemia and hypogastrinemia have been described in vivo, and several cells that express cholecystokinin (CCK)B/gastrin receptors have been used for analysis of intracellular signaling pathways initiated by biologically active amidated gastrins. The binding of gastrin or CCK to their common cognate receptor triggers the activation of multiple signal transduction pathways that relay the mitogenic signal to the nucleus and promote cell proliferation. A rapid increase in the synthesis of lipid-derived second messengers with subsequent activation of protein phosphorylation cascades, including mitogen-activated protein kinase, is an important early response to these signaling peptides. Gastrin and CCK also induce rapid Rho-dependent actin remodeling and coordinate tyrosine phosphorylation of cellular proteins including the non-receptor tyrosine kinases p125fak and Src and the adaptor proteins p130cas and paxillin. This article reviews recent advances in defining the role of gastrin and CCK in the control of cell proliferation in normal and cancer cells and in dissecting the signal transduction pathways that mediate the proliferative responses induced by these hormonal GI peptides in a variety of normal and cancer cell model systems.

Management of severe gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) affects more than one third of the population. It is generally a chronic condition and has the potential to be serious. Some patients with GERD experience persistent daytime or nighttime heartburn and some sustain severe damage, including ulceration, stricture, and Barrett's esophagus, which can predispose to development of adenocarcinoma. Extraesophageal manifestations of GERD can include otolaryngologic, respiratory, and cardiac problems. Severe GERD responds best to agents that suppress gastric acid secretion. Of these, proton pump inhibitors (PPIs) provide the most effective control of gastric acidity and are, therefore, the medical treatment of choice. In fact, nonresponse to a PPI should raise the suspicion that the diagnosis is not GERD. Proton pump inhibitors are quickly becoming the treatment of choice for GERD, especially for severe or refractory cases. For patients whose GERD is refractory even to PPIs or who are unwilling to face years of PPI therapy, antireflux surgery remains an option.

Factors that affect results of the 13C urea breath test in Japanese patients

BACKGROUND

The 13C urea breath test (UBT) is considered to be the most accurate way of diagnosing Helicobacter pylori infection. Our objective was to investigate the accuracy of the UBT in Japanese patients and the association of UBT values with histological findings.

MATERIALS AND METHODS

A total of 169 consecutive patients were studied by endoscopy with histology, by serology with IgG antibody and test serum pepsinogen (PG), and by UBT. The association between UBT values and histological findings and the PG I / II ratio were analyzed in H. pylori-positive patients.

RESULTS

Of 169 Japanese patients, 135 were H. pylori-positive on both histology and serology analysis, 27 were H. pylori-negative on both histology and serology analysis, and 7 patients showed differing results. Using a cutoff value of 2.5 per thousand, test sensitivity was 100%, while specificity was 96%. Among the 135 H. pylori-positive patients, a significant relation was observed between UBT value and H. pylori colonization density of the corpus and antrum, neutrophil activity of the antrum, atrophy, and intestinal metaplasia of the corpus in the H. pylori-positive patients. Also, UBT values correlated with the PG I /II ratio. In multivariate analysis, the PG I /II ratio was the most important factor related to UBT values (odds ration [OR], 4. 99; 95% confidence interval, 1.60-15.55).

CONCLUSIONS

The UBT is an accurate method for detecting H. pylori infection in the Japanese population, which shows a high prevalence of atrophic gastritis. Values are affected by H. pylori infection and by the severity of atrophic gastritis.

An OmpA-like protein from Acinetobacter spp. stimulates gastrin and interleukin-8 promoters

Bacterial overgrowth in the stomach may occur under conditions of diminished or absent acid secretion. Under these conditions, secretion of the hormone gastrin is elevated. Alternatively, bacterial factors may directly stimulate gastrin. Consistent with this hypothesis, we found that mice colonized for 2 months with a mixed bacterial culture of opportunistic pathogens showed an increase in serum gastrin. To examine regulation of gene expression by bacterial proteins, stable transformants of AGS cells expressing gastrin or interleukin-8 (IL-8) promoters were cocultured with live organisms. Both whole-cell sonicates and a heat-stable fraction were also coincubated with the cells. A level of 10(8) organisms per ml stimulated both the gastrin and IL-8 promoters. Heat-stable proteins prepared from these bacterial sonicates stimulated the promoter significantly more than the live organism or unheated sonicates. A 38-kDa heat-stable protein stimulating the gastrin and IL-8 promoters was cloned and found to be an OmpA-related protein. Immunoblotting using antibody to the OmpA-like protein identified an Acinetobacter sp. as the bacterial species that expressed this protein and colonized the mouse stomach. Moreover, reintubation of mice with a pure culture of the Acinetobacter sp. caused gastritis. We conclude that bacterial colonization of the stomach may increase serum gastrin levels in part through the ability of the bacteria to produce OmpA-like proteins that directly stimulate gastrin and IL-8 gene expression. These results implicate OmpA-secreting bacteria in the activation of gastrin gene expression and raise the possibility that a variety of organisms may contribute to the increase in serum gastrin and subsequent epithelial cell proliferation in the hypochlorhydric stomach.

Nalpha-methyl histamine and histamine stimulate gastrin release from rabbit G-cells via histamine H2-receptors

BACKGROUND

Gastrin release by Helicobacter pylori may be an important step in the pathway leading to duodenal ulceration. A histamine H3-receptor agonist was found to release gastrin from antral mucosal fragments; this was interpreted as being due to suppression of somatostatin release. H. pylori is reported to produce Nalpha-methyl histamine (NalphaMH), which is an agonist of H3 as well as other histamine receptors. H. pylori infection also recruits mast cells, which release histamine.

AIM

To determine the direct effects of histamine receptor agonists on isolated gastrin cells.

METHODS

Rabbit G-cells were prepared by countercurrent elutriation and cultured on 24-well plates.

RESULTS

NalphaMH (10-6-10-4 M) caused a dose-dependent increase in gastrin release from a basal level of 2.3 +/- 0.2% total cell content (TCC; mean +/- S.E.M.) to a maximum of 5.1 +/- 0.7%, an increase of 117% (P < 0. 005) above basal. This was abolished by the H2-antagonist ranitidine (10-5 M), but not by immunoblockade with anti-somatostatin antibody, the H1-antagonist chlorpheniramine (10-5 M) or the H3-antagonist thioperamide (10-4 M). The histamine H2-receptor agonist dimaprit (10-6-10-4 M) increased gastrin release from 2.4 +/- 0.2% to 3.6 +/- 0.2% TCC (P < 0.001). Gastrin release was also stimulated by histamine (10-7-10-4 M) from a basal value of 3.0 +/- 0.3% to 5.4 +/- 0.5% TCC (P < 0.001). This also was inhibited by ranitidine (10-5 M) (P < 0.01).

CONCLUSION

NalphaMH and histamine release gastrin from G-cells via H2-receptors; this might contribute to H. pylori-associated hypergastrinaemia.

Dyspepsia and heartburn

Dyspepsia and heartburn are the two cardinal symptoms of foregut dysfunction. When confronting such a problem, that physician must first learn to discern between the two, because treatment can be quite different for the conditions presenting with these symptoms. This article details the approach to work-up and treatment of patients presenting with dyspepsia or heartburn.

Fundoplication provides effective and durable symptom relief in patients with Barrett's esophagus

BACKGROUND

Columnar-lined esophagus with intestinal metaplasia (IM), also called Barrett's esophagus, is a manifestation of severe gastroesophageal reflux (GER) and may predict poor symptom relief and high failure rate after fundoplication. We compared symptom scores and reoperation rates in GER patients with and without Barrett's esophagus.

METHODS

Between July 1992 and July 1997, 646 patients underwent fundoplication (626 laparoscopic). Of 150 endoscopic biopsies of suspected columnar-lined esophagus, 80 confirmed IM, 50 identified cardiac or fundic epithelium, and 20 revealed only esophagitis. Typical GER symptoms were scored by patients preoperatively and postoperatively (0 to 4 scale). We compared symptom response (Wilcoxon rank sum test) and failure rates (t test) in patients with IM and GER controls without IM. Preoperative data were available for 74 IM patients and 496 controls. One-year follow-up was available in 45 IM patients and 301 controls. Intermediate follow-up (2 to 5 years) was available in 20 IM patients and 99 controls.

RESULTS

Preoperatively and postoperatively, patients with IM reported heartburn, regurgitation, and dysphagia scores similar to controls. Procedure failure, requiring redo fundoplication, appeared more likely in IM patients than controls (6.3% versus 2.5%), but this difference did not reach statistical significance (P = 0.061).

CONCLUSION

Fundoplication provides equivalent symptom relief for patients with and without IM.

Histological and anatomic changes in Barrett's esophagus after antireflux surgery

OBJECTIVE

The best treatment approach for patients with documented Barrett's esophagus remains controversial. There is currently no well designed prospective study examining the effect of successful antireflux surgery on Barrett's esophagus.

METHODS

Fourteen patients with histologically proven Barrett's esophagus underwent standard antireflux surgery followed by careful endoscopic, histological, and symptomatic follow-up beginning at 2-4 wk after surgery. Pre- and postoperative symptoms, patient functional assessment scores, lower esophageal sphincter pressure, and 24-h pH studies were compared, in addition to monitoring patients for evidence of squamous re-epithelialization and dysplasia.

RESULTS

Patients demonstrated statistically significant improvement in symptoms, functional assessment scores, lower esophageal sphincter pressure, and 24-h pH assessments after antireflux surgery. Two patients had complete disappearance of short segments (2 and 3 cm) of Barrett's esophagus. Ten additional patients demonstrated evidence of squamous re-epithelialization, although biopsies often showed mixed components of squamous and columnar epithelium. No patients showed progression of dysplastic change, and four patients demonstrated the disappearance of low grade dysplasia throughout the period of the study.

CONCLUSION

Successful antireflux surgery can produce at least partial squamous re-epithelialization in Barrett's metaplasia and stabilization or apparent improvement in dysplasia in some patients without the need for long term medication. Continued long term endoscopic and histologic follow-up is still required in all patients with Barrett's esophagus after antireflux surgery.

Proton pump inhibitors. Pharmacology and rationale for use in gastrointestinal disorders

Proton pump inhibitors (PPIs) are drugs which irreversibly inhibit proton pump (H+/K+ ATPase) function and are the most potent gastric acid-suppressing agents in clinical use. There is now a substantial body of evidence showing improved efficacy of PPIs over the histamine H2 receptor antagonists and other drugs in acid-related disorders. Omeprazole 20 mg/day, lansoprazole 30 mg/day, pantoprazole 40 mg/day or rabeprazole 20 mg/day for 2 to 4 weeks are more effective than standard doses of H2-receptor antagonists in healing duodenal and gastric ulcers. Patients with gastric ulcers should receive standard doses of PPIs as for duodenal ulcers but for a longer time period (4 to 8 weeks). There is no conclusive evidence to support the use of a particular PPI over another for either duodenal or gastric ulcer healing. For Helicobacter pylori-positive duodenal ulceration, a combination of a PPI and 2 antibacterials will eradicate H. pylori in over 90% of cases and significantly reduce ulcer recurrence. Patients with H. pylori-positive gastric ulcers should be managed similarly. PPIs also have efficacy advantages over ranitidine and misoprostol and are better tolerated than misoprostol in patients taking nonsteroidal anti-inflammatory drugs (NSAIDs). In endoscopically proven gastro-oesophageal reflux disease, standard daily doses of the PPIs are more effective than H2-receptor antagonists for healing, and patients should receive a 4 to 8 week course of treatment. For severe reflux, with ulceration and/or stricture formation, a higher dose regimen (omeprazole 40 mg, lansoprazole 60 mg, pantoprazole 80 mg or rabeprazole 40 mg daily) appears to yield better healing rates. There is little evidence that PPIs lead to resolution of Barrett's oesophagus or a reduction of subsequent adenocarcinoma development, but PPIs are indicated in healing of any associated ulceration. In Zollinger-Ellison syndrome, PPIs have become the treatment of choice for the management of gastric acid hypersecretion.

[Association of Biermer's anemia and gastric carcinoid tumors]

BACKGROUND

The occurrence of gastric carcinoid tumors during the cure of pernicious anemia has been reported in the literature. Concerning a new case, we review physiopathological data of this infrequent association.

CASE REPORT

We report the case of a 47-year-old women with pernicious anemia in which gastroscopy found two small tumors developed from enterochromaffin-like cells.

CONCLUSION

These tumors are usually latent and developed from enterochromaffin-like cells. The pathologic and histologic diagnosis is based on positive chromogranin A immunomarking. The physiopathological mechanism studies are in favour of the predominant part of hypergastrinemia following achlorhydria. Usually, evolution is benign and surgical or endoscopic resection recommended.

Medical therapy of gastroesophageal reflux and management of esophageal strictures

The goals of modern medical therapy for gastroesophageal reflux disease are threefold: first, eliminate symptoms; second, heal injured esophageal mucosa; third, manage and/or prevent complications. Selection of a particular medical regimen depends on the severity of the disease, effectiveness of the therapy, cost, and convenience of the medical regimen. An accurate diagnosis needs to be made in patients suspected with esophageal strictures. If there is a treatable underlying disease, specific therapy is essential. The goal of dilation therapy should be established and set about to accomplish in a timely, but unhurried fashion. Fluoroscopy and wire-guided dilators should be used liberally, especially for difficult strictures.

An analysis of 8305 cases of carcinoid tumors

BACKGROUND

Carcinoid tumors are unusual and most reports are anecdotal or limited in number. A series of 2837 cases was published in 1975. No recent large series is available.

METHODS

The authors evaluated 5468 cases identified by the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute (NCI) from 1973 to 1991 together with 2837 carcinoid cases previously registered by 2 earlier NCI programs. To the authors' knowledge, the 8305 carcinoid tumors analyzed represent the largest current epidemiology series to date.

RESULTS

The most frequent sites for carcinoids were the gastrointestinal (GI) tract (73.7%) and the bronchopulmonary system (25.1%). Within the GI tract, most occurred in the small bowel (28.7%), appendix (18.9%), and rectum (12.6%). For all sites, age-adjusted incidence rates were highest in African American males (2.12 per 100,000 population per year). Associated noncarcinoid tumors were frequent in conjunction with small intestinal (16.6%), appendiceal (14.6%), and colonic carcinoids (13.1%). The highest percentage of nonlocalized lesions were noted for pancreatic (76.1%), colonic (71.2%), and small intestinal carcinoids (70.7%) and this corresponded to their poor 5-year survival rates (34.1%, 41.6%, and 55.4%, respectively). The best 5-year survival rates were recorded for appendiceal (85.9%), bronchopulmonary (76.6%), and rectal carcinoids (72.2%). These exhibited invasive growth or metastatic spread in only 35.4%, 27.2%, and 14.2% of cases, respectively.

CONCLUSIONS

Carcinoids appear to have increased in incidence in the past 20 years. In part, this may be due to different surgical rules of the various registries, improved diagnostic technology, and increased awareness. A cumulative analysis of all types of carcinoid tumors in the SEER group indicates that in 45.3% metastases are already evident at the time of diagnosis. The overall 5-year survival rate of all carcinoid tumors regardless of site was 50.4% +/- 6.4%.

An analysis of 8305 cases of carcinoid tumors

BACKGROUND

Carcinoid tumors are unusual and most reports are anecdotal or limited in number. A series of 2837 cases was published in 1975. No recent large series is available.

METHODS

The authors evaluated 5468 cases identified by the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute (NCI) from 1973 to 1991 together with 2837 carcinoid cases previously registered by 2 earlier NCI programs. To the authors' knowledge, the 8305 carcinoid tumors analyzed represent the largest current epidemiology series to date.

RESULTS

The most frequent sites for carcinoids were the gastrointestinal (GI) tract (73.7%) and the bronchopulmonary system (25.1%). Within the GI tract, most occurred in the small bowel (28.7%), appendix (18.9%), and rectum (12.6%). For all sites, age-adjusted incidence rates were highest in African American males (2.12 per 100,000 population per year). Associated noncarcinoid tumors were frequent in conjunction with small intestinal (16.6%), appendiceal (14.6%), and colonic carcinoids (13.1%). The highest percentage of nonlocalized lesions were noted for pancreatic (76.1%), colonic (71.2%), and small intestinal carcinoids (70.7%) and this corresponded to their poor 5-year survival rates (34.1%, 41.6%, and 55.4%, respectively). The best 5-year survival rates were recorded for appendiceal (85.9%), bronchopulmonary (76.6%), and rectal carcinoids (72.2%). These exhibited invasive growth or metastatic spread in only 35.4%, 27.2%, and 14.2% of cases, respectively.

CONCLUSIONS

Carcinoids appear to have increased in incidence in the past 20 years. In part, this may be due to different surgical rules of the various registries, improved diagnostic technology, and increased awareness. A cumulative analysis of all types of carcinoid tumors in the SEER group indicates that in 45.3% metastases are already evident at the time of diagnosis. The overall 5-year survival rate of all carcinoid tumors regardless of site was 50.4% +/- 6.4%.

Serum antibodies to commensal oral and gut bacteria vary with age

This study examined the relationship between serum antibody levels to selected bacteria from the commensal oral and gut flora with increased age in a healthy adult population. A total of 116 healthy subjects were studied consisting of the following age groups: 20-39 years (group A), 40-59 years (group B), 60-79 years (group C) and 80+ years (group D). Only significantly lower mean IgM antibody levels to Streptococcus mutans strain Guy's serotype c were observed in older age groups (P < 0.001). With Actinomyces viscosus NCTC 10951 significantly reduced IgM levels (P < 0.02) and significantly elevated IgA levels were observed with increased age (P < 0.05). IgA and IgG antibodies to Escherichia coli NCTC 10418 were increased significantly in the older age groups (P < 0.001), whilst a trend toward lower levels of IgM antibodies was recorded with age. No changes in IgA antibodies to Streptococcus faecalis NCTC 775 were observed but the lowest level of IgM antibodies were detected in the oldest age group (P < 0.05). Mean specific activity was decreased with age with IgM antibodies to the oral bacteria and increased with age with IgG and IgA antibodies to E. coli. Overall, our results suggest a general reduction in serum IgM antibody responses. This impairment in the circulatory IgM immune response may contribute to the increased occurrence of infections in the elderly.

The role of Helicobacter pylori in pathogenesis: the spectrum of clinical outcomes

Helicobacter pylori is probably the commonest bacterial infection worldwide and is now accepted as the cause of chronic active type B gastritis. Most patients continue through life with a chronic superficial gastritis while some develop either duodenal or gastric ulcer. In a very small proportion the lymphoid reaction to H. pylori infection appears to progress to become a mucosal associated lymphoid tissue (MALT) lymphoma, while in others the evidence suggests that chronic superficial gastritis progresses to atrophy, the loss of gastric acid secretory capacity and the development of gastric cancer. The mechanisms involving H. pylori infection in peptic ulceration are increasingly well understood and H. pylori is now accepted as having a critical role in duodenal ulcer, where the prevalence of infection is 90 to 95%. More important is the dramatic reduction in duodenal ulcer recurrence after successful eradication of the organism to about 4% in a year compared to recurrences of up to 80% in those who ulcers have been healed but in whom the infection persists. There is also increasing evidence for the involvement of H. pylori in gastric ulcer, where infection is seen in between 60 and 80%, and there is a similar dramatic reduction in recurrence following cure of H. pylori infection. The progression of H. pylori gastritis from the acute infection to chronic superficial gastritis, predominantly antral gastritis or a pangastritis with increasing atrophy appears to be associated with the differing outcomes seen in this disease. Moreover, there is increasing data on the roles played by bacterial heterogeneity and the virulence of the organism, host factors such as the HLA genotype and immune response, environmental factors and the age of acquisition of infection play in determining these clinical outcomes of the disease.

Cobalamin

Cobalamin (vitamin B12) is an essential nutrient derived exclusively from bacterial sources. It is an essential cofactor for three known enzymatic reactions. Untreated deficiency, caused by either the autoimmune disease pernicious anemia or nutritional lack, results in a macrocytic anemia and/or subacute combined degeneration of the spinal cord and is eventually fatal. Cobalamin in serum is bound to two proteins, transcobalamin and haptocorrin. The former is responsible for the essential delivery of cobalamin to most tissues. Inadequate tissue availability of cobalamin results in increased concentration of methylmalonic acid and homocyst(e)ine due to inhibition of methylmalonyl-CoA mutase and methionine synthase, respectively. Strict vegetarians have long been known to be at risk of cobalamin deficiency, which develops insidiously over many years. It is now clear that a significant number of the elderly and HIV-positive individuals are also at increased risk of deficiency. Any individual with reduced ability to split cobalamin from food-protein may also become deficient even though intrinsic factor is present. Diagnosis of cobalamin deficiency has frequently relied on total serum cobalamin and the Schilling test. Newer approaches such as analysis of methylmalonic acid, homocyst(e)ine, holotranscobalamin, anti-intrinsic factor antibodies, and serum gastrin may provide more cost-effective testing, as well as identify those with a covert deficiency.