Epidemic hypochlorhydria

Gastric Peptides-Gastrin and Somatostatin

Gastric acid secretion (i) facilitates digestion of protein as well as absorption of micronutrients and certain medications, (ii) kills ingested microorganisms, including Helicobacter pylori, and (iii) prevents bacterial overgrowth and enteric infection. The principal regulators of acid secretion are the gastric peptides gastrin and somatostatin. Gastrin, the major hormonal stimulant for acid secretion, is synthesized in pyloric mucosal G cells as a 101-amino acid precursor (preprogastrin) that is processed to yield biologically active amidated gastrin-17 and gastrin-34. The C-terminal active site of gastrin (Trp-Met-Asp-Phe-NH₂ ) binds to gastrin/CCK₂ receptors on parietal and, more importantly, histamine-containing enterochromaffin-like (ECL) cells, located in oxyntic mucosa, to induce acid secretion. Histamine diffuses to the neighboring parietal cells where it binds to histamine H₂ -receptors coupled to hydrochloric acid secretion. Gastrin is also a trophic hormone that maintains the integrity of gastric mucosa, induces proliferation of parietal and ECL cells, and is thought to play a role in carcinogenesis. Somatostatin, present in D cells of the gastric pyloric and oxyntic mucosa, is the main inhibitor of acid secretion, particularly during the interdigestive period. Somatostatin exerts a tonic paracrine restraint on gastrin secretion from G cells, histamine secretion from ECL cells, and acid secretion from parietal cells. Removal of this restraint, for example by activation of cholinergic neurons during ingestion of food, initiates and maximizes acid secretion. Knowledge regarding the structure and function of gastrin, somatostatin, and their respective receptors is providing novel avenues to better diagnose and manage acid-peptic disorders and certain cancers. Published 2020. Compr Physiol 10:197-228, 2020.

Gastric Parietal Cell Physiology and Helicobacter pylori-Induced Disease

Acidification of the gastric lumen poses a barrier to transit of potentially pathogenic bacteria and enables activation of pepsin to complement nutrient proteolysis initiated by salivary proteases. Histamine-induced activation of the PKA signaling pathway in gastric corpus parietal cells causes insertion of proton pumps into their apical plasma membranes. Parietal cell secretion and homeostasis are regulated by signaling pathways that control cytoskeletal changes required for apical membrane remodeling and organelle and proton pump activities. Helicobacter pylori colonization of human gastric mucosa affects gastric epithelial cell plasticity and homeostasis, promoting epithelial progression to neoplasia. By intervening in proton pump expression, H pylori regulates the abundance and diversity of microbiota that populate the intestinal lumen. We review stimulation-secretion coupling and renewal mechanisms in parietal cells and the mechanisms by which H pylori toxins and effectors alter cell secretory pathways (constitutive and regulated) and organelles to establish and maintain their inter- and intracellular niches. Studies of bacterial toxins and their effector proteins have provided insights into parietal cell physiology and the mechanisms by which pathogens gain control of cell activities, increasing our understanding of gastrointestinal physiology, microbial infectious disease, and immunology.

Helicobacter pylori-Induced Changes in Gastric Acid Secretion and Upper Gastrointestinal Disease

Appropriate management of Helicobacter pylori infection of the human stomach is evolving and remains a significant clinical challenge. Acute infection results in hypochlorhydria, whereas chronic infection results in either hypo- or hyperchlorhydria, depending upon the anatomic site of infection. Acute hypochlorhydria facilitates survival of the bacterium and its infection of the stomach. Interestingly, most patients chronically infected with H. pylori manifest a pangastritis with reduced acid secretion due to bacterial virulence factors, inflammatory cytokines, and various degrees of gastric atrophy. While these patients are predisposed to develop gastric adenocarcinoma (~1%), there is increasing evidence from population studies that they are also protected from gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC). Eradication of H. pylori, in these patients, may provoke GERD in predisposed individuals and may be a contributory factor for the rising incidence of refractory GERD, BE, and EAC observed in Westernized societies. Only ~10% of chronically infected patients, mainly the young, manifest an antral predominant gastritis with increased acid secretion due to a decrease in somatostatin and increase in gastrin secretion; these patients are predisposed to develop peptic ulcer disease. H. pylori-induced changes in acid secretion, in particular hypochlorhydria, may allow ingested microorganisms to survive transit through the stomach and colonize the distal intestine and colon. Such perturbation of gut microbiota, i.e. dysbiosis, may influence human health and disease.

The Esophageal and Gastric Microbiome in Health and Disease

The esophagus and stomach are host to their own population of bacteria, which differs in health and disease. Helicobacter pylori uniquely colonizes only gastric mucosa, but an increasing number of bacteria is now isolated from the gastric juice and gastric mucosa, including Lactobacillus. The presence of H pylori alters populations of other gastric bacteria with a marked reduction in diversity. Alterations in intragastric acidity may be the cause or the consequence of changes in the microbial populations of the stomach. Esophageal inflammation is associated with an altered microbiota in gastroesophageal reflux disease, Barrett's esophagus, eosinophilic esophagitis, and cancer.

Gastric emptying is altered with the presence of gastritis

Helicobacter pylori infection and gastritis can cause symptoms suggestive of altered gastrointestinal function; however, it is unclear if H. pylori influences gastric motility. This study assessed gastric emptying rates in mouse models of gastritis. Gastritis was induced in C57BL/6 mice via ethanol treatment or via challenge with H. pylori or H. felis. Gastric emptying rates of nutrient and non-nutrient liquids were assessed with the non-invasive (13)C-breath test, and the results were compared to healthy mice. Gastric emptying of the non-nutrient liquid was unaltered with the presence of gastritis; however, gastric emptying of the nutrient liquid was accelerated after a 4-week infection with H. pylori. H. felis infection and ethanol treatment caused a more severe gastritis and disruptions to the normal gastric emptying. Changes to gastric emptying in mouse models of gastritis are associated with the presence of nutrients. Altered gastric emptying may contribute to symptoms commonly reported in humans with gastritis.

Helicobacter pylori: review of research findings

Helicobacter pylori attracted widespread interest from gastroenterologists because of its potential aetiologic role in disorders of the upper gastrointestinal tract. Based on extensive microbiological studies, Campylobacter pylori was renamed Helicobacter pylori, and the organism represents a new genus of bacteria. It is generally accepted that H. pylori causes chronic, non-specific gastritis (type B gastritis). The inflammatory response occurs even though the bacterium does not penetrate the gastric epithelium; it is found on the surface of and adjacent to the epithelium. The clinical significance of histological gastritis is unknown. The bacterium is often found in asymptomatic subjects. In Caucasian adults, the prevalence of infection increases with increasing age. Higher rates of infection are found in blacks and Hispanics than would be expected for their age. Whether these different rates are the result of racial or socioeconomic factors is not known. It is theorized, but not proven, that high rates of infection with H. pylori at an early age may explain the high incidence of gastric carcinoma found in Hispanic populations. H. pylori is found in almost every patient with duodenal ulcer disease, although no direct evidence for a causal relationship exists. Indirect evidence is based on the findings that if H. pylori infection is eradicated, ulcer recurrence is less likely (up to one year of follow-up). A small percentage of patients have a relapse despite eradication of the organism, suggesting a role for other factors in duodenal ulcer disease. The role of H. pylori in gastric ulcer disease is unknown. Seventy to eighty per cent of patients with gastric ulcer have evidence of H. pylori infection, and preliminary data seem to support the existence of two distinct aetiologic groups: those with gastric ulcers related to H. pylori infection and those with gastric ulcers related to use of non-steroidal anti-inflammatory drugs. The role of H. pylori in non-ulcer dyspepsia is unknown. Some clinicians believe that H. pylori causes non-ulcer dyspepsia and treat these patients for H. pylori infection. However, the data supporting this practice are poor. Treatment is only recommended for patients with resistant duodenal ulcers and patients who have frequent relapses of duodenal ulcers and who are willing to take triple-drug therapy (bismuth compounds, metronidazole, tetracycline) for the infection. As 95% of patients with duodenal ulcer have evidence of H. pylori infection, there is probably little need to confirm the diagnosis of H. pylori infection.

Childhood Helicobacter pylori infection and growth impairment in developing countries: a vicious cycle?

We hypothesize that infection with the gastric pathogen Helicobacter pylori in children in developing countries is the initiator of a vicious cycle of events that result ultimately in malnutrition and growth impairment. Acute infection with H. pylori is accompanied by hypochlorhydria, which facilitates the acquisition of other enteropathogens because of removal of the gastric acid barrier, which then results in diarrheal disease and iron-deficiency anemia. This is likely to occur most frequently in developing regions where the prevalence of H. pylori infection is disproportionately high and multiple enteric coinfections are common. The consequent synergistic impact of diarrheal disease and micronutrient deficiency on growth and cognitive function in children has significant public health implications for socioeconomic development in these countries.

Helicobacter Connections

After preliminary studies in 1981, Marshall and Warren conducted a study in which the new bacterium Helicobacter pylori was cultured. In that series, 100 % of 13 patients with duodenal ulcer were found to be infected. The hypothesis that peptic ulcer was caused by a bacterial infection was not accepted without a fight. Most experts believed that Helicobacter was a harmless commensal, infecting people who had ulcers for some other reason. In response, Marshall drank a culture of Helicobacter to prove that the bacteria could infect a healthy person and cause gastritis. The truth behind peptic ulcers was revealed; that is, very young children acquired the Helicobacter organism, leading to a chronic infection which caused a lifelong susceptibility to peptic ulcers. Marshall developed new treatments for the infection and diagnostic tests which allowed the hypothesis to be evaluated and proven. After 1994 Helicobacter was generally accepted as the cause of most gastroduodenal diseases including peptic ulcer and gastric cancer. As a result of this knowledge, treatment is a simple procedure, and stomach surgery has become a rarity.

Acute Helicobacter pylori infection is followed by an increase in diarrheal disease among Peruvian children

BACKGROUND

Cohort and case-crossover studies were conducted to evaluate whether new Helicobacter pylori infections are followed by increased diarrhea.

METHODS

Participants were 6-month-old to 12-year-old shantytown residents living near Lima, Peru. Baseline data were collected from community households. Health interviews were completed daily, and sera, drawn every 4 months, were tested for H pylori immunoglobulin G. Diarrhea rates among newly H pylori-infected (seroconverting) children were compared with rates among persistently uninfected and infected children using cohort and case-crossover analyses.

RESULTS

Sera were obtained from 345 children from January 1, 1995, through September 1, 1997. H pylori incidence was 12% per year (36 H pylori infections in 109 866 seronegative days). In adjusted cohort analyses, seroconverters had more diarrhea days (rate ratio: 2.0; 95% confidence interval: 1.6-2.4), episodes, and sick days in the year after infection than did uninfected children; and more diarrhea days and sick days than did persistently infected children. This effect was strongest in the first 2 months. Case-crossover analyses supported these findings.

CONCLUSION

Preventing H pylori infection may help reduce pediatric diarrheal disease.

The emerging nosocomial pathogens Cryptosporidium, Escherichia coli O157:H7, Helicobacter pylori, and hepatitis C: epidemiology, environmental survival, efficacy of disinfection, and control measures

New and emerging infectious diseases pose a threat to public health and may be responsible for nosocomial outbreaks. Cryptosporidium parvum and Escherichia coli are gastrointestinal pathogens that have caused nosocomial infections via person-to-person transmission, environmental contamination, or contaminated water or food. Helicobacter pylori has been transmitted via inadequately disinfected endoscopes. Finally, hepatitis C may be acquired by healthcare personnel by percutaneous or mucous membrane exposure to blood or between patients by use of contaminated blood products or via environmental contamination. Rigorous adherence to Standard Precautions, Contact Precautions for patients with infectious diarrhea, disinfection of environmental surfaces, and appropriate disinfection of endoscopes are adequate to prevent nosocomial acquisition of these pathogens.

Acute gastritis with hypochlorhydria: report of 35 cases with long term follow up

BACKGROUND

Between 1976 and 1987, 35 cases of acute gastritis with hypochlorhydria (AGH) were seen in our research laboratory. The aims of this study were to determine the natural history of AGH and the role of Helicobacter pylori in its pathogenesis.

METHODS

Archived serum and gastric biopsy samples obtained from AGH subjects were examined for evidence of H pylori colonisation. Twenty eight of 33 (85%) surviving AGH subjects returned a mean of 12 years after AGH for follow up studies, including determination of H pylori antibodies, basal and peak acid output, endoscopy, and gastric biopsies. A matched control group underwent the same studies.

RESULTS

Archived material provided strong evidence of new H pylori acquisition in a total of 14 subjects within two months, in 18 within four months, and in 22 within 12 months of recognition of AGH. Prevalence of H pylori colonisation at follow up was 82% (23 of 28) in AGH subjects, significantly (p<0.05) higher than in matched controls (29%). Basal and peak acid output returned to pre-AGH levels in all but two subjects.

CONCLUSIONS

One of several possible initial manifestations of H pylori acquisition in adults may be AGH. While H pylori colonisation usually persists, hypochlorhydria resolves in most subjects.

The effect of Helicobacter pylori eradication on intragastric pH during dosing with lansoprazole or ranitidine

BACKGROUND

The antisecretory effect of omeprazole on intragastric pH is decreased in the absence of Helicobacter pylori.

AIM

To investigate the effect of H. pylori eradication on intragastric pH during lansoprazole or ranitidine dosing in 41 asymptomatic H. pylori-positive subjects.

METHOD

Two groups of healthy H. pylori-positive volunteers were investigated. One group was dosed with lansoprazole 30 mg at 08.00 hours for at least 8 days, before and after 2 weeks of placebo-controlled double-blind eradication therapy using ranitidine bismuth citrate 400 mg b.d. and clarithromycin 500 mg b.d. The other group was dosed with ranitidine 300 mg at 23.00 hours for at least 8 days using the same trial design. An upper endoscopy was performed to establish H. pylori status by rapid urease test, culture and histology before both periods of dosing. Twenty-four hour intragastric pH recording was performed on the final day of all periods of dosing.

RESULTS

H. pylori eradication significantly decreased the intragastric pH reached during lansoprazole treatment throughout all periods of the day. Intragastric pH during ranitidine treatment was not affected by H. pylori eradication, except for the late-night period.

CONCLUSION

H. pylori eradication has a more pronounced effect on the acid-inhibiting properties of lansoprazole than on those of ranitidine.

Seroprevalence of immunoglobulin G antibodies against Helicobacter pylori among endoscopy personnel in Japan

BACKGROUND

The seroprevalence of immunoglobulin G antibodies against Helicobacter pylori in endoscopy personnel was determined to investigate whether gastrointestinal endoscopists and endoscopy nurses in Japan are at an increased risk for H. pylori infection and to clarify risk factors for H. pylori infection during endoscopy.

METHODS

One hundred twenty-one gastrointestinal endoscopists and endoscopy nurses provided personal information, including their observance of infection-control measures, by means of self-administered questionnaire. One hundred one age-matched healthy individuals undergoing routine physical examinations served as controls. Serum samples from each subject were examined with enzyme-linked immunosorbent assay for the presence of IgG antibodies against H. pylori.

RESULTS

Among younger subjects (< 40 years old), endoscopists and endoscopy nurses had higher seropositive rates than did control subjects (p < 0.05). Among older subjects (> or = 40 years old), the seropositive rate did not differ between endoscopy personnel and control subjects (p = 0.2174). However, among older seropositive subjects, endoscopy personnel had significantly higher antibody titers than did control subjects (p < 0.01). Older seropositive endoscopists performed significantly more examinations per month than did their seronegative colleagues (p < 0.05). Furthermore, younger seropositive endoscopy nurses performed significantly more examinations per month than did seronegative nurses (p < 0.05).

CONCLUSIONS

Gastrointestinal endoscopists and endoscopy nurses in Japan are at high risk for H. pylori infection. The risk of H. pylori infection is correlated with the frequency of endoscopic examinations, especially in older gastrointestinal endoscopists and younger endoscopy nurses.

Helicobacter pylori

Helicobacter pylori infection causes peptic ulcer disease, gastric adenocarcinoma, gastric lymphoma, and probably nonulcer dyspepsia. Although the prevalence of infection is declining over time, the organism still infects approximately one half of the world's population. Only a minority will ever suffer serious consequences from their infection. This article reviews current knowledge about H. pylori and presents some of the dilemmas surrounding clinical and public health approaches to this widespread pathogen.

Helicobacter pylori lipopolysaccharide inhibits acid secretion in pylorus-ligated conscious rats

To examine the effect of Helicobacter pylori lipopolysaccharide on gastric secretion, the present study was carried out using pylorus ligated conscious rats. Intraperitoneal administration of Helicobacter pylori lipopolysaccharide significantly inhibited gastric acid secretion (4 hr) in a dose-dependent manner (0.033-1.0 mg/rat). The Helicobacter pylori lipopolysaccharide (1 mg/rat)-induced acid inhibition was still observed 8 hr after injection. Gastric acid secretion (4 hr) was compared in the rats that had received intraperitoneal administration of 1 mg/rat dose of Helicobacter pylori lipopolysaccharide or saline alone 24 hr before. There was no significant difference in gastric acid secretion between the saline- and H. pylori lipopolysaccharide-treated rats. These results suggest for the first time that H. pylori lipopolysaccharide may inhibit acid production, and this acid inhibition may be long-lasting. It is also demonstrated that this anti-secretory action of H. pylori lipopolysaccharide has a reversible effect on gastric secretion. All these results suggest that H. pylori lipopolysaccharide might be involved in the low acid secretory function seen in patients with acute H. pylori infection.

Seroprevalence of Helicobacter pylori infection in medical staff in Shanghai

BACKGROUND

The epidemiology of Helicobacter pylori is still under investigation. It is postulated that the human stomach is the natural reservoir and that spread occurs by oral-oral or fecal-oral transmission. The aim of this study was to determine whether medical staff, especially endoscopy unit personnel, are at an increased risk of acquiring H. pylori infection.

METHODS

An enzyme-linked immunosorbent assay technique was used to detect circulating H. pylori IgG antibodies in 1050 medical staff from 16 hospitals in Shanghai, including 125 GI endoscopists, 45 endoscopy unit nurses, 71 gastroenterologists not doing endoscopy, 105 nurses working in gastroenterology wards, 417 internists, and 287 general nurses. This group was compared with an age-matched population obtained from the same urban area of the city.

RESULTS

The overall prevalence of H. pylori infection in total medical staff was 70.0%, compared to 44.6% in general population (P < 0.0001). Age-adjusted comparisons between subgroups of medical staff were made. The prevalence of H. pylori in GI endoscopists was 82.4%, which is significantly higher than 66.4% in internists and 65.8% in general nurses (all, P < 0.01) but not significantly different from 77.7% in endoscopy unit nurses or from 74.2% in nurses working in gastroenterology wards (all, P > 0.05). Further analysis did not show any significant difference in the prevalence of H. pylori between other subgroups. The prevalence of H. pylori infection in GI endoscopists increased with the number of years of practice.

CONCLUSIONS

Medical staff, especially endoscopy unit personnel, are at increased risk of infection with H. pylori. These findings strongly suggest the medical practice and endoscopy procedures are risk factors for H. pylori infection and support person-to-person transmission in this setting, probably from patients to medical staff.

The effect of Helicobacter pylori on gastric acid secretion by isolated parietal cells from a guinea pig. Association with production of vacuolating toxin by H. pylori

BACKGROUND

One of the features of Helicobacter pylori infection in the human stomach seems to be disordered gastric acid secretion. The effect of vacuolating toxin (VT) produced by H. pylori on gastric acid secretion was examined.

METHODS

VT(+)(toxigenic) and VT(-)(nontoxigenic) strains of H. pylori were cultured in brucella broth. The culture supernatant was added to isolated parietal cells, and acid secretion and intracellular adenosine 3'5'-cyclic phosphate (cAMP) and Ca2+ levels were measured with the 14C-aminopyrine (14C-AP) method, with 125I radioimmunoassay (RIA), and with the fura-2 fluorescence method, respectively.

RESULTS

In the VT(+) strain a considerable inhibitory effect on 14C-AP accumulation was observed. However, the VT(-) strain had no significant effect on intracellular c-AMP and Ca2+.

CONCLUSIONS

The VT(+) strain of H. pylori has an inhibitory effect on gastric acid secretion, whereas the VT(-) strain does not. This inhibitory effect was not associated with the response of second messengers. It is speculated that VT produced by H. pylori has a direct action on H(+)-K+ adenosine triphosphatase in parietal cells.

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.

Review article: is Helicobacter pylori transmitted by the gastro-oral route?

The manner in which Helicobacter pylori is transmitted is of fundamental importance when considering strategies for its control, yet to date no satisfactory explanation has been advanced to account for its spread from person to person. This is surprising for a disease that affects 50% of the world's population. Attempts to culture H. pylori from faecal material and saliva have met with difficulty, casting some doubt on the likelihood of a faeco-oral or oro-oral route of transfer. The infection is easily passed from person to person by gastric intubation. The hypothesis advanced in this paper is that the natural route of transmission is by gastric juice, specifically as a result of epidemic vomiting in childhood. This theory is supported by literature indicating that acute infection with H. is characterized by vomiting of achlorhydric mucus that may serve as a vehicle for transmission. The hypothesis is consistent with most of the epidemiological data that have been published on H. pylori infection, including its association with childhood overcrowding, the lack of a fixed hot water supply and disadvantaged social conditions.

Prevention of Helicobacter pylori infection

A gastroenterologist, treating a patient with H. pylori, must decide whether the unit of treatment is only the ill individual, or the family, perhaps including close contacts. If it is the family and close contacts, is it all family members and contacts, or are there some ages, relationships, or clinical characteristics that increase the risk of transmission to the patient after successful treatment of their infection? In preventing reinfection, the available data suggest: the natural infectious dose has not been determined infection may occur from oral or faecal shedding children are more infectious than adults socio-economic factors are important in any comparison of infection rates food and water seem unlikely vehicles in the developed world travel in the third world may increase risk of infection seropositivity in adults predominantly reflects exposure in childhood infection is frequently with more than one strain reinfections are not more frequent in families with other members infected reinfections are infrequent with strains different from the original strain reinfection might be more frequent in developing countries no need for all family members to be treated to reduce reinfection rates. In considering vaccine, the available data suggest: breast milk IgA can reduce infection rate antibodies induced by vaccine may reduce infection in animals late benefit of childhood vaccination in developed countries probable early benefit of childhood vaccination in developing countries vaccination of already infected adults would have cost-benefit.

Rabbit and ferret parietal cell inhibition by Helicobacter species

We tested sonicates of Helicobacter pylori, H. mustelae, and H. felis for inhibition of acid secretion in rabbit and ferret isolated gastric glands. Three H. pylori strains, two of three H. mustelae strains, and two H. felis strains significantly inhibited acid secretion in rabbit cells by 95.2-93.3%, 55.9% and 96.4%, and 83.4-96%, respectively. All Helicobacter strains examined inhibited acid secretion by ferret cells by 65.3-76.8%, 89.1-97.6%, and 85.8-92.8%. H. pylori inhibited acid secretion after stimulation with histamine and isobutylmethylxanthine or with 8-bromo-cyclic adenosine monophosphate (P < 0.05 for all tests). These findings demonstrate that acid inhibition is a property common to the three Helicobacter species tested. It occurs independently of the mammalian origin of the parietal cell, and it does not involve blockade of histamine-2 receptors.

Long-term prospective study of Helicobacter pylori in nonulcer dyspepsia

Helicobacter pylori is present in up to 87% of patients with nonulcer dyspepsia. This study assessed the effect of eradicating Helicobacter pylori infection on the symptoms of nonulcer dyspepsia at four weeks and one year after treatment. Dyspepsia was assessed on the frequency and severity of six symptoms [epigastric pain (night and day), nausea and vomiting, upper abdominal discomfort, and regurgitation] where each symptom was scored from 0 to 4. Helicobacter pylori status was assessed before treatment and four weeks after treatment with histology and microbiology, and at one year with a carbon-13 urea breath test. Eighty-three patients (23 males, 60 females; mean age 56.3 years; mean symptom duration 3.6 months) with nonulcer dyspepsia and Helicobacter pylori infection entered the study. Seventy-five were available at one year follow-up. Four weeks after treatment, the mean symptom score improved in those with eradication (6.95-2.3, P = 0.01, N = 41) or persistent infection (6.69-3.0, P = 0.015, N = 42). At one year, those with persistent Helicobacter pylori infection (N = 38, score 5.24) had a higher score than those remaining clear of infection (N = 24, score 1.4, P < 0.0001) and those with reinfection (N = 13, score 2.2, P < 0.0001). In addition, persistent Helicobacter pylori infection was associated with more additional treatments than those with eradication (34/38 versus 4/37, P < 0.001). These results suggest that Helicobacter pylori plays an important role in the symptoms of nonulcer dyspepsia.

Helicobacter pylori infection. A reversible cause of hypergastrinemia and hyperchlorhydria which may mimic Zollinger-Ellison syndrome

The present report describes two patients with fasting hypergastrinemia, gastric acid hypersecretion, and Helicobacter pylori gastritis. Provocative testing for Zollinger-Ellison syndrome was negative and imaging studies did not demonstrate an intra-abdominal mass. Following eradication of the Helicobacter pylori infection, the fasting hypergastrinemia resolved in both patients and in one patient the gastric acid hypersecretion also resolved. The implications of this case on the differential diagnosis of Zollinger-Ellison syndrome are discussed.

Helicobacter pylori: the missing link in perspective

Helicobacter pylori, an organism responsible for a common human infection, may act as a cofactor to produce gastrointestinal disease in a significant minority. The exact mechanisms of transmission are still unclear, but likely involve direct person-to-person spread and fecal-oral or waterborne/environmental transmission. Infection is a necessary condition for the development of duodenal ulcers and chronic nonspecific gastritis. It also likely contributes to the development of gastric ulcers, and the intestinal-type gastric carcinoma, but further studies are needed to confirm these hypotheses. Multiple effective treatment regimens currently exists. We recommend using bismuth, metronidazole, and tetracycline as the initial regimen of choice. Unfortunately, the relative importance of bacterial virulence factors is still unclear when compared with host susceptibility factors, and much knowledge needs to be gained about pathogenesis before vaccine development can proceed.

Helicobacter pylori is associated with alterations in intestinal gas profile among patients with nonulcer dyspepsia

The pathogenesis of nonulcer dyspepsia (NUD) is unknown. Gas and postprandial bloating are frequent symptoms. The role of Helicobacter pylori (HP) in the pathogenesis of NUD is controversial. We studied the intestinal gas profile of NUD patients (N = 34) at baseline and after lactulose administration. The prevalence of hydrogen and methane producers was similar among HP+ and HP- patients. Breath H2 concentrations in response to lactulose showed significantly greater rise among HP+ subjects (P < 0.0001). HP positivity was associated with higher total breath excretion for H2 and methane combined (2984 +/- 1038 vs 1776 +/- 521 ppm/hr) compared to HP- subjects (P < 0.05). There was no correlation between peak H2 and methane levels. The role of alterations in intestinal gas in producing symptoms in HP+ patients with NUD needs further investigation.

Effects of Helicobacter pylori on histamine and carbachol stimulated acid secretion by human parietal cells

Helicobacter pylori (H pylori) infection is associated with hypo, normal, and hypersecretory disorders of the gastric mucosa. Pathophysiological pathways by which H pylori interacts with acid secretion are still unclear. The effects of H pylori on (14C) aminopyrine uptake by human parietal cells were examined as an indirect assay for acid secretion. Isolated oxyntic glands were stimulated with submaximal concentrations of histamine or carbachol and incubated with sonicates of different H pylori strains. Omeprazole and sonicates of Campylobacter jejuni served as positive and negative controls, respectively. Two of four H pylori strains reduced hydrochloric acid sequestration within the parietal cells significantly and in a dose dependent manner in up to 80%. Interaction with acid secretion may therefore constitute a factor contributing to a distinct pathogenicity of H pylori strains.

The role of Helicobacter pylori in acid-peptic disease

Acid peptic disease is common, and its management is costly. Less than a decade ago, the traditional theories regarding the etiology and pathogenesis of acid peptic disease were upset by the discovery of Helicobacter pylori infection in association with chronic active gastritis. A substantial body of investigation after that discovery has established this infection as the major cause of human chronic active gastritis and has defined a critical role for H. pylori in the etiology, pathophysiology, and treatment of duodenal ulcer disease. Furthermore, evidence is accumulating to link H. pylori to gastric ulcers, non-ulcer dyspepsia, and even gastric carcinoma. Research has clarified some unique features of the organism that have been put to advantage in the development of diagnostic tests, and it has also clarified some features of the infection that make it difficult to treat. Although treatment is decidedly beneficial for certain patient subsets, simpler and more effective therapy is needed.

Non-immunological defence mechanisms of the gut

Non-immunological defence mechanisms represent an important line of intestinal defence in addition to humoral and cellular immunity. This review summarises the evidence for the role of the non-immunological defence system. Protective factors that have been amply documented are gastric juice, intestinal motility, and intestinal flora. Components of pancreatic juice, lysozyme, and epithelial cell turnover may also be involved. Special attention is given to gastric acid, infection with Helicobacter pylori, and hypochlorhydria and their association with infectious diarrhoea. Epidemic hypochlorhydria is discussed since this increases sensitivity to intestinal infections in third world countries.

Helicobacter pylori and luminal gastric pH. Relationships in nonulcer dyspepsia

The relationships between gastric pH and Helicobacter pylori infection were studied in 37 consecutive subjects affected with nonulcer dyspepsia. Each underwent esophagogastroduodenoscopy with multiple gastric biopsies for both H. pylori and histologic assessment, and 24-hr antral pH monitoring. H. pylori was harbored by 59.5% of the subjects with whole gastric spread of infection in all but one patient. Histologic gastritis was shown in 70.3% of the subjects. H. pylori was strongly associated with gastritis, both antral nonatrophic and multifocal atrophic. The ranges of 24-hr pH values were 1.3-6.9 in the H. pylori-positive and 1.2-6.8 in the H. pylori-negative group. Differences in pH values between the two groups were not significant. Moreover, the mean percent time duration of pH above 2, 4, and 6 did not significantly differ between the two groups. Therefore, this study has shown that chronic H. pylori infection is not related to luminal gastric pH.

Detection of Helicobacter pylori in stomach tissue by use of a monoclonal antibody

Monoclonal antibodies were produced against an acid glycine extract of Helicobacter pylori ATCC 43504T. One of these appeared to be specific for H. pylori; it recognized all H. pylori isolates by an indirect immunofluorescence assay (IIF) but it did not cross-react with the other strains tested, including different species of the genera Helicobacter, Campylobacter, and Wolinella. Different strains of members of the families Enterobacteriaceae and Pseudomonadaceae or other gram-negative bacteria tested also gave negative reactions. Indirect immunofluorescence assay of antral biopsy specimens identified 54 of 56 infected patients (96.4%), and it may be able to detect nonviable organisms after antibiotic therapy.

Acute Helicobacter pylori infection: clinical features, local and systemic immune response, gastric mucosal histology, and gastric juice ascorbic acid concentrations

The symptomatology of a case of acute infection with Helicobacter pylori is described, together with the accompanying changes in gastric mucosal histology, local and systemic humoral immune response, and gastric ascorbic acid concentration. The patient was an endoscopist, previously negative for the carbon-14 urea breath test, who had a week of epigastric pain and then became asymptomatic. H pylori was detected by culture of antral biopsy specimens and was still present after 74 days. Five days after infection the histological findings showed acute neutrophilic gastritis; by day 74 changes of chronic gastritis were evident. The patient seroconverted by IgG enzyme linked immunosorbent assay by day 74, but a mucosal IgM and IgA response was evident as early as day 14. Infection was accompanied by a transient hypochlorhydria but a sustained fall in gastric juice ascorbic acid concentration.

A comparison of symptoms between non-ulcer dyspepsia patients positive and negative for Helicobacter pylori

The role of Helicobacter pylori infection in the symptom complex associated with non-ulcer dyspepsia is uncertain, despite the presence of the organism in a high proportion of these patients. In order to exclude physician bias in history taking, 18 patients (9 female) diagnosed as non-ulcer dyspepsia, after endoscopy and gallbladder ultrasonography, underwent computer interrogation using the Glasgow Diagnostic System for Dyspepsia (GLADYS). Five antral and 3 fundal endoscopic biopsies from these patients were also histologically examined for the presence of Helicobacter pylori and quantitatively analysed for polymorph and chronic inflammatory cell densities per mm2 of lamina propria using computer-linked image analysis. In the group of 9/18 patients who were positive for Helicobacter pylori, there were significantly higher antral and fundal inflammatory cell counts than in negative patients. However, analysis of the GLADYS interrogation data showed no significant positive relationships between Helicobacter pylori positivity and any gastrointestinal symptoms. These results confirm a significant association between Helicobacter pylori and superficial gastritis but suggest that non-ulcer dyspepsia in patients with Helicobacter pylori colonisation is probably not a clinically identifiable and distinct syndrome.

Disinfection of endoscopic equipment

Patients undergoing endoscopy are at risk of infection from the use of contaminated equipment. Dangers arise from the transmission of organisms from one patient to another and from the introduction of opportunist organisms which colonize endoscopic equipment on storage and can lead to sepsis and death in those who are immunocompromised and at ERCP. Staff are in danger from needle-stick injury and sensitivity to aldehyde disinfectants. These risks can be eliminated by careful attention to disinfection techniques. The most important part of endoscope disinfection is thorough mechanical cleaning first, followed by 5-10 min total immersion of the instrument and all channels in 2% glutaraldehyde (or the equivalent). At the end of the endoscopy list, following the disinfection protocol, all equipment should be dried internally and externally prior to storage. Staff must be fully aware of the risks of infection in endoscopy, be protected from hepatitis B by vaccination, and be fully trained in disinfection techniques. Glutaraldehyde should be used only in closed systems or in well-ventilated areas with the operator protected from direct contact from splashing and fumes. Institutions should designate an individual to be responsible for preparing, monitoring and overseeing disinfection procedures within the endoscopy room and for ensuring that regular microbiological testing of equipment (including automatic disinfecting machines) is undertaken.

N-nitrosoproline excretion in the presence and absence of gastric disease

N-nitrosoproline (NPRO) excretion, an indicator of endogenous nitrosation, was measured in a group of hospital inpatients who were identified by endoscopy and gastric biopsy as either having gastric lesions or having healthy stomachs. NPRO was assayed in background 24-hour urine samples and samples collected after loading doses of nitrate and L-proline. The presence of gastric lesions was associated with altered gastric pH and concomitant changes in gastric juice nitrate and nitrite concentration. Gastric juice pH increased with increasing severity of gastric disease (P = 0.031) and patients with normal stomachs had a lower gastric pH than those with chronic atrophic gastritis (CAG) (3.0 vs. 6.5, P = 0.017). The changes in gastric juice nitrate concentration were in the reverse direction (P = 0.002 for trend) with normal patients having higher mean levels than CAG patients (12.7 vs. 5.5 micrograms/ml, P less than 0.0001). Nitrite concentration increased with severity of gastric disease but the results were not significant (normal, 82.9 vs. CAG, 223.4 ng/ml, P = 0.069). No association was found between the presence of gastric lesions and increased urinary NPRO excretion. Mutagenic activity was not detected in any of the gastric juice samples.

Helicobacter pylori in Gambian children with chronic diarrhoea and malnutrition

Infection with Helicobacter pylori (formerly Campylobacter pylori) was studied by measuring antibody titres to H pylori in Gambian children. Serological evidence of infection was found in 12 of 82 (15%) infants aged less than 20 months; this increased to 62 of 135 (46%) in those aged 40-60 months. Positive serology was found in 41 of 77 (53%) infants with chronic diarrhoea and malnutrition (mean age 19 months, range 5-36) compared with 18 of 70 (26%) of age matched healthy controls and nearly a quarter (12/49, 24%) of age matched undernourished (marasmic) subjects. These data show that infection with H pylori is common in the Gambia and that in infancy this infection is associated with chronic diarrhoea and malnutrition.

Immunostaining of antral gastrin cells is quantitatively increased in Heliobacter pylori gastritis

The amount of gastrin-like immunostaining in gastrin (G) cells of the antral mucosa was quantified using a computer-assisted method of measuring immunoreaction product. Biopsies from 25 patients without Heliobacter-like organisms and 60 patients with varying degrees of infection were immunostained for gastrin. Twenty-five G cells from each patient were measured both subjectively and by image analysis. Gastrin-like immunoreactivity was found to be significantly increased in the presence of Heliobacter-like organisms.

Campylobacter pylori and gastroduodenal disease

Campylobacter pylori is a newly described, spiral-shaped, gram-negative bacillus that is oxidase positive, catalase positive, and urease positive and grows slowly in culture. Although observed in human tissue at the beginning of the century, it was not cultured until 1982. Because there are significant morphological and genetic differences between this organism and other species of Campylobacter, it will probably be reclassified in a new genus. Current information indicates that the organism primarily resides in the stomach tissue of humans and nonhuman primates and may occasionally spread to the esophagus or other parts of the alimentary tract under appropriate conditions. Significant evidence has accumulated in the last several years to show that it causes gastritis, and there is mounting evidence that it may participate in the development of duodenal ulcers. It may also be associated with gastric ulcers and nonulcer dyspepsia. It can be detected in patients by culture of biopsy specimens or histological staining of biopsy tissue. Indirect evidence for the presence of the organism can be obtained by detection of urease in a tissue biopsy specimen, by urea breath tests, or by detection of specific antibody. It may not be necessary to implement these procedures for routine use, however, until the role of the organism can be defined better. Ultimately, the discovery of this organism may lead to radical changes in the diagnosis and treatment of gastric disease.

Effect of a Campylobacter pylori protein on acid secretion by parietal cells

The uptake of [14C]-aminopyrine by rabbit gastric epithelial cells was used as an indirect assay for acid secretion from parietal cells. Campylobacter pylori strains, isolated from the stomachs of 3 patients with chronic gastritis, duodenal ulcer, and near-normal mucosa, respectively, inhibited acid secretion as effectively as 10(-4) mol/l cimetidine. The inhibition occurred with whole organisms and with sonicates. Preliminary characterisation suggested that the inhibition was due to a nondialysable protein. The inhibitor was not toxic to gastric epithelial cells. This bacterial product may explain the hypochlorhydria seen in man acutely infected with C pylori.

Seroepidemiological study of the immune response to Campylobacter pylori in potential risk groups

To gain more understanding of the epidemiology of Campylobacter pylori infection, the immune response to the organism was studied in the following selected potential risk groups: endoscopy staff (n = 45), dental staff (n = 58), orphanage children (n = 24), psychiatric patients (n = 58), and family contacts of Campylobacter pylori-infected patients (n = 55). The frequency of an IgG and IgA antibody response in the different groups was determined by the immunoblot method and compared with that in an appropriate control group (n = 189). The frequency of a positive antibody response was dependent on age (p less than 0.0001) but not on sex. When results were corrected for age by logistic regression analysis, all groups, with the exception of dental staff and orphanage children, revealed a significantly raised frequency of an IgA and combined IgG/IgA immune response compared to controls. There was not a significant difference for the IgG response, except in orphanage children. It is concluded that endoscopy staff, family contacts of Campylobacter pylori-infected patients and people living in closed communities such as psychiatric patients and orphanage children must be considered as risk groups for Campylobacter pylori infection. The findings support the notion that person-to-person spread and a common source are the predominant modes of transmission of Campylobacter pylori in addition to endoscopes.

Bacteria in ulcer pathogenesis

A great deal of information about the spiral bacteria of the stomach has accumulated in the past 5 years. These bacteria, currently named Campylobacter pylori but likely to be renamed as a new genus, have adapted to living beneath the mucus layer and above the gastric surface mucous cells. When metaplastic gastric mucous cells are also present in the duodenal bulb, C. pylori may also get a foothold in this latter location. Observations of the high prevalence of C. pylori in patients with gastritis and with duodenal ulcers, and the slightly lower prevalence in patients with gastric ulcer, have led to the hypothesis that the bacteria play an aetiological role in these three conditions. There is now fairly convincing evidence that the organisms can cause active chronic gastritis. The most persuasive of this comes from reports of the rapid development of gastritis and symptoms in two volunteers who swallowed the organism, plus two other series of accidental challenges. Other evidence is provided by the waning and waxing of gastritis, which has been correlated in several studies with clearance followed by recrudescence of the organisms. The role of the bacterium in peptic ulcer is less certain. The present data do not provide strong evidence for a causal role in gastric ulcer, although we cannot rule out that it may be important in some. The very high prevalence in patients with duodenal ulcer, including one series in children (who rarely harbour the organism), raises the distinct possibility that the bacteria play an aetiological role in this form of ulcer. Reports of ulcer healing with antibiotics and of lower recurrence rates in those cleared of the organism, increase the possibility, However, methodological flaws in some studies, plus the usual need for confirmation of key studies, indicate that we should await more definitive evidence before accepting that duodenal ulcer can be an infectious disease.

Acid secretion and serum gastrin levels in individuals with Campylobacter pylori

Campylobacter pylori may cause gastritis and has been proposed as an etiologic factor in the development of peptic ulcer. However, it may be an acid-sensitive microbe and before it can be implicated in the pathogenesis of peptic ulcer, it should be consistently found in ulcer patients with normal acid secretion. Thirty-six patients with C. pylori by Warthin-Starry stain underwent gastric analysis; 25 were normochlorhydric and 11 hypochlorhydric. Ulcers were present in 19 normochlorhydric patients (10, gastric; 9, duodenal) and 2 hypochlorhydric patients (gastric). Median basal acid output was higher for those with duodenal ulcer (38 mmol/h) than gastric ulcer (28 mmol/h) or miscellaneous endoscopic features (33 mmol/h). The hypergastrinemia seen in 12 patients with negative secretin provocation tests was believed to be due to various nongastrinoma conditions. Campylobacter pylori was found in 6 normogastrinemic patients with elevated acid output and in 1 gastrinoma patient with marked acid hypersecretion. Histologic chronic gastritis was present in all subjects and 29 had active chronic gastritis. Twenty-three patients were taking H2-receptor antagonists at the time of diagnosis which did not seem to interfere with culture results. Using standard acid secretory tests, we conclude that C. pylori can survive in a wide range of acid conditions.