Bacteria in the aetio-pathogenesis of gastric cancer: a review

Is Helicobacter pylori infection associated with pancreatic cancer? A systematic review and meta-analysis of observational studies

Background and Objectives

Recent observational studies have investigated the association between Helicobacter pylori (H. pylori) infection and pancreatic cancer with conflicting data. Therefore, we conducted a systematic review and meta-analysis to assess the potential association.

Design

This is a systematic review and meta-analysis.

Methods

We searched three databases (PubMed, Embase, and Web of Science) from inception to 30 August 2022. The summary results as odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) were pooled by generic inverse variance method based on random-effects model.

Results

A total of 20 observational studies involving 67,718 participants were included in the meta-analysis. Meta-analysis of data from 12 case-control studies and 5 nested case-control studies showed that there was no significant association between H. pylori infection and the risk of pancreatic cancer (OR = 1.20, 95% CI = 0.95-1.51, p = 0.13). Similarly, we also did not find significant association between cytotoxin-associated gene A (CagA) positive strains, CagA negative strains, vacuolating cytotoxin gene A (VacA) positive strains H. pylori infection, and the risk of pancreatic cancer. Meta-analysis of data from three cohort studies showed that H. pylori infection was not significantly associated with an increased risk of incident pancreatic cancer (HR = 1.26, 95% CI = 0.65-2.42, p = 0.50).

Conclusion

We found insufficient evidence to support the proposed association between H. pylori infection and increased risk of pancreatic cancer. To better understand any association, future evidence from large, well-designed, high-quality prospective cohort studies that accounts for diverse ethnic populations, certain H. pylori strains, and confounding factors would be useful to settle this controversy.

Inverse relations between Helicobacter pylori infection and risk of esophageal precancerous lesions in drinkers and peanut consumption

BACKGROUND

Helicobacter pylori (H. pylori) is a Gram-negative bacterium found in the upper digestive tract. Although H. pylori infection is an identified risk factor for gastric cancer, its role in esophageal squamous cell carcinoma (ESCC) remains a topic of much debate.

AIM

To evaluate the association between H. pylori infection and the risk of precancerous lesions of ESCC, and further explore the association between dietary factors and the risk of H. pylori infection.

METHODS

Two hundred patients with esophageal precancerous lesions (EPL) aged 63.01 ± 6.08 years and 200 healthy controls aged 62.85 ± 6.03 years were included in this case-control study. Epidemiological data and qualitative food frequency data were investigated. Enzyme-linked immunosorbent assay measuring serum immunoglobulin G antibodies was used to determine H. pylori seropositivity. An unconditional logistic regression model was used to assess the association between H. pylori infection and EPL risk dichotomized by gender, age, and the use of tobacco and alcohol, as well as the association between dietary factors and the risk of H. pylori infection.

RESULTS

A total of 47 (23.5%) EPL cases and 58 (29.0%) healthy controls had positive H. pylori infection. An inverse relation between H. pylori infection and the risk of EPL was found in the group of drinkers after adjustment for covariates [odds ratio (OR) = 0.32, 95% confidence interval (95%CI): 0.11-0.95]. Additionally, peanut intake was significantly associated with a decreased risk of H. pylori infection (OR = 0.39, 95%CI: 0.20-0.74).

CONCLUSION

Our study suggested that H. pylori infection may decrease the risk of EPL for drinkers in a rural adult Chinese population, and the consumption of peanut may reduce the risk of H. pylori infection. These findings should be framed as preliminary evidence, and further studies are required to address whether the mechanisms are related to the localization of lesions and alcohol consumption.

Microbiome Signatures in a Fast- and Slow-Progressing Gastric Cancer Murine Model and Their Contribution to Gastric Carcinogenesis

Gastric cancer is the third most common cause of death from cancer in the world and infection with Helicobacter pylori (H. pylori) is the main cause of gastric cancer. In addition to Helicobacter infection, the overall stomach microbiota has recently emerged as a potential factor in gastric cancer progression. Previously we had established that mice deficient in myeloid differentiation primary response gene 88 (MyD88, Myd88^-/- ) rapidly progressed to neoplasia when infected with H. felis. Thus, in order to assess the role of the microbiota in this fast-progressing gastric cancer model we investigated changes of the gastric microbiome in mice with different genotypic backgrounds: wild type (WT), MyD88-deficient (Myd88^-/- ), mice deficient in the Toll/interleukin-1 receptor (TIR) domain-containing adaptor-inducing interferon-β (TRIF, Trif ^Lps2), and MyD88- and TRIF-deficient (Myd88^-/- /Trif ^Lps2, double knockout (DKO)) mice. We compared changes in alpha diversity, beta diversity, relative abundance, and log-fold differential of relative abundance ratios in uninfected and Helicobacter infected mice and studied their correlations with disease progression to gastric cancer in situ. We observed an overall reduction in microbial diversity post-infection with H. felis across all genotypes. Campylobacterales were observed in all infected mice, with marked reduction in abundance at 3 and 6 months in Myd88^-/- mice. A sharp increase in Lactobacillales in infected Myd88^-/- and DKO mice at 3 and 6 months was observed as compared to Trif ^Lps2 and WT mice, hinting at a possible role of these bacteria in gastric cancer progression. This was further reinforced upon comparison of Lactobacillales log-fold differentials with histological data, indicating that Lactobacillales are closely associated with Helicobacter infection and gastric cancer progression. Our study suggests that differences in genotypes could influence the stomach microbiome and make it more susceptible to the development of gastric cancer upon Helicobacter infection. Additionally, increase in Lactobacillales could contribute to faster development of gastric cancer and might serve as a potential biomarker for the fast progressing form of gastric cancer.

Systematic Review with Meta-analysis: Association of Helicobacter pylori Infection with Esophageal Cancer

Background

Helicobacter pylori is an important carcinogenic factor in gastric cancer. Studies have shown that Helicobacter pylori infection is inversely associated with certain diseases such as esophageal cancer and whose infection appears to have a “protective effect.” At present, the relationship between Helicobacter pylori infection and esophageal cancer remains controversial. This study was designed to investigate the relationship between Helicobacter pylori infection and the risk of esophageal cancer in different regions and ethnicities.

Methods

Systematic search of the articles on the relationship between Helicobacter pylori infection and esophageal cancer from the database with the duration time up to December 2018. This systematic review was performed under the MOOSE guidelines.

Results

This meta-analysis included 35 studies with 345,886 patients enrolled. There was no significant correlation between Helicobacter pylori infection and esophageal squamous cell carcinoma in the general population (OR: 0.84; 95% CI: 0.64-1.09/OR: 0.74; 95% CI: 0.54-0.97). However, a significant correlation was found in the Middle East (OR: 0.34; 95% CI: 0.22-0.52/95% CI: 0.26-0.44). There was no significant difference in the prevalence of Helicobacter pylori between the case group and the control group in esophageal adenocarcinoma (8.87% vs. 9.67%). The pooled OR was 0.55 (95% CI: 0.43-0.70) or 0.23 (95% CI: 0.15-0.36). When grouped by match or not, the pooled OR of the nonmatching group and the matching group was 0.48/0.21 (95% CI: 0.36-0.65/95% CI: 0.13-0.36) and 0.73/0.71 (95% CI: 0.57-0.92/95% CI: 0.60-0.84), respectively.

Conclusion

In the general populations, no significant association was found between Helicobacter pylori infection and the risk of esophageal squamous cell carcinoma. However, lower risk was found in the Middle East. Helicobacter pylori infection may reduce the risk of esophageal adenocarcinoma, but such “protection effect” may be overestimated.

The Microbiota and Pancreatic Cancer

Pancreatic cancer is one of the most lethal diseases. In pancreatic cancer development and progression, genetic (gene mutations and activation of oncogenes) and environmental factors (smoking, alcohol consumption, type 2 diabetes mellitus, obesity) play an essential role. Recently, molecular studies revealed that dysbiosis of microbiota also has influence on cancer development. Research indicates that bacteria and viruses can lead to chronic inflammation, antiapoptotic changes, cell survival, and cell invasion. This review presents bacteria and viruses oncogenic for the pancreas. Possible mechanisms of carcinogenic action are also described.

Serum Pepsinogens and Helicobacter Pylori are not Associated with Esophageal Squamous Cell Carcinoma in a High-Risk Area in China

Aims and background

The role of serum pepsinogen level and Helicobacter pylori infection in esophageal carcinoma remains controversial. It may be a risk or protective factor, or without association with esophageal carcinoma. We prospectively examined associations between serum pepsinogen status, H pylori infection and the risk of esophageal squamous cell carcinoma in the Chinese population.

Methods

In the present study, 1501 subjects from a community-based general population of Northern China were included. The incidence of esophageal carcinoma among the subjects was registered during a 15-year follow-up period by annual home visit, and the risks of low serum pepsinogen level and H pylori infection in the development of ESCC were evaluated using logistic regression.

Results

The total accumulated incidence of ESCC in the cohort was 666/100,000 during the 15-year follow-up. Notably, all the cases were verified to be ESCC. Logistic regression analysis showed that age ≥60 (OR = 9.67; 95% CI, 2.797–33.423) was the only risk factor for esophageal squamous cell carcinoma in the population. There was no significant association between sex, H pylori infection, pepsinogen level (PG I ≤70 ng/ml alone, PG I/II ratio ≤3 alone, or PG I ≤70 ng/ml and PG I/II ratio ≤3) and esophageal squamous cell carcinoma.

Conclusions

In this prospective study, neither H pylori infection nor abnormal pepsinogen status had a predictive role for the development of esophageal squamous cell carcinoma in the rural population of China.

Helicobacter pylori infection, chronic corpus atrophic gastritis and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort: A nested case-control study

The association between H. pylori infection and pancreatic cancer risk remains controversial. We conducted a nested case-control study with 448 pancreatic cancer cases and their individually matched control subjects, based on the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, to determine whether there was an altered pancreatic cancer risk associated with H. pylori infection and chronic corpus atrophic gastritis. Conditional logistic regression models were applied to calculate odds ratios (ORs) and corresponding 95% confidence intervals (CIs), adjusted for matching factors and other potential confounders. Our results showed that pancreatic cancer risk was neither associated with H. pylori seropositivity (OR = 0.96; 95% CI: 0.70, 1.31) nor CagA seropositivity (OR = 1.07; 95% CI: 0.77, 1.48). We also did not find any excess risk among individuals seropositive for H. pylori but seronegative for CagA, compared with the group seronegative for both antibodies (OR = 0.94; 95% CI: 0.63, 1.38). However, we found that chronic corpus atrophic gastritis was non-significantly associated with an increased pancreatic cancer risk (OR = 1.35; 95% CI: 0.77, 2.37), and although based on small numbers, the excess risk was particularly marked among individuals seronegative for both H. pylori and CagA (OR = 5.66; 95% CI: 1.59, 20.19, p value for interaction < 0.01). Our findings provided evidence supporting the null association between H. pylori infection and pancreatic cancer risk in western European populations. However, the suggested association between chronic corpus atrophic gastritis and pancreatic cancer risk warrants independent verification in future studies, and, if confirmed, further studies on the underlying mechanisms.

Environmental risk factors for pancreatic cancer: an update

Pancreatic cancer (PC) is one of the most aggressive diseases. Only 10 % of all PC cases are thought to be due to genetic factors. Here, we analyzed the most recently published case-control association studies, meta-analyses, and cohort studies with the aim to summarize the main environmental factors that could have a role in PC. Among the most dangerous agents involved in the initiation phase, there are the inhalation of cigarette smoke, and the exposure to mutagenic nitrosamines, organ-chlorinated compounds, heavy metals, and ionizing radiations. Moreover, pancreatitis, high doses of alcohol drinking, the body microbial infections, obesity, diabetes, gallstones and/or cholecystectomy, and the accumulation of asbestos fibers seem to play a crucial role in the progression of the disease. However, some of these agents act both as initiators and promoters in pancreatic acinar cells. Protective agents include dietary flavonoids, marine omega-3, vitamin D, fruit, vegetables, and the habit of regular physical activity. The identification of the factors involved in PC initiation and progression could be of help in establishing novel therapeutic approaches by targeting the molecular signaling pathways responsive to these stimuli. Moreover, the identification of these factors could facilitate the development of strategies for an early diagnosis or measures of risk reduction for high-risk people.

Pathogenic Microorganisms and Pancreatic Cancer

BACKGROUND

Pancreatic cancer is one of the most lethal cancers worldwide. No effective screening methods exist, and available treatment modalities do not effectively treat the disease. Established risk factors for pancreatic cancer, including smoking, chronic pancreatitis, obesity and type 2 diabetes mellitus, collectively account for less than half of all pancreatic cancer cases. Accumulating reports have demonstrated that there is an association between pathogenic microorganisms and pancreatic cancer.

SUMMARY

A substantial amount of preclinical and clinical evidence suggests that microbiota are likely to influence pancreatic carcinogenesis. This review summarizes the literature on studies examining infections that have been linked to pancreatic cancer.

KEY MESSAGE

Helicobacter pylori infection may be a risk factor for pancreatic cancer; chronic hepatitis virus and oral microbiota may also play a role in pancreatic carcinogenesis.

PRACTICAL IMPLICATIONS

Considering the worldwide burden of the disease, the association between microbiota and pancreatic cancer in this review may provide new ideas to prevent and treat pancreatic cancer more efficiently. Further studies in this direction are urgently needed.

Helicobacter pylori and the molecular pathogenesis of intestinal-type gastric carcinoma

Gastric carcinoma is an inflammation-related cancer caused by long-term infection with the human bacterial pathogen, Helicobacter pylori. The pattern of acute-on-chronic inflammation causes progressive mucosal damage which may result in atrophy with metaplastic epithelia and eventually gastric cancer. Recently, it has been recognized that H. pylori can also cause genetic instability such as double-stranded DNA breaks and can produce gene activation and silencing via epigenetic pathways. As genetic instability is the hallmark of cancer, we highlight recent progress in understanding the gastric carcinogenesis in relation to H. pylori-related inflammation, H. pylori-induced double-stranded DNA breakage and aberrant gene expression as well as the mechanisms and role of H. pylori-associated epigenetic change in gene expression.

Eradication of gastric cancer is now both possible and practical

In 1994, Helicobacter pylori was declared a human carcinogen. Evidence has now accumulated to show that at least 95% of gastric cancers are etiologically related to H. pylori. An extensive literature regarding atrophic gastritis and its effects on acid secretion, gastric microflora, and its tight association with gastric cancer has been rediscovered, confirmed, and expanded. Methods to stratify cancer risk based on endoscopic and histologic findings or serologic testing of pepsinogen levels and H. pylori testing have been developed producing practical primary and secondary gastric cancer prevention strategies. H. pylori eradication halts progressive mucosal damage. Cure of the infection in those with non-atrophic gastritis will essentially prevent subsequent development of gastric cancer. For all, the age-related progression in cancer risk is halted and likely reduced as eradication reduces or eliminates mucosal inflammation and reverses or reduces H. pylori-associated molecular events such aberrant activation-induced cytidine deaminase expression, double strand DNA breaks, impaired DNA mismatch repair and aberrant DNA methylation. Those who have developed atrophic gastritis/gastric atrophy however retain some residual risk for gastric cancer which is proportional to the extent and severity of atrophic gastritis. Primary and secondary cancer prevention starts with H. pylori eradication and cancer risk stratification to identify those at higher risk who should also be considered for secondary cancer prevention programs. Japan has embarked on population-wide H. pylori eradication coupled with surveillance targeted to those with significant remaining risk. We anticipate that countries with high gastric cancer burdens will follow their lead. We provide specific recommendations on instituting practical primary and secondary gastric cancer prevention programs as well identifying research needed to make elimination of gastric cancer both efficient and cost effective.

Association between Helicobacter pylori infection and pancreatic cancer development: a meta-analysis

BACKGROUND

Pancreatic cancer is one of the most troublesome malignancies with dismal prognosis. H. pylori has been recognized as a type I carcinogen. Several studies have evaluated the association between H. pylori infection and pancreatic cancer development, however, the conclusions are inconsistent.

METHODS

Literature search was carried out in PubMed, EMBASE, Cochrane Library and CNKI databases to identify eligible researches. We performed overall meta-analysis of all studies included and subgroup analysis based on regional distribution. Quality of the studies (assessed by Newcastle-Ottawa quality assessment scale for case-control studies) and CagA+ strains of H. pylori were taken into consideration, and we conducted additional analyses including high-quality researches and those concerning CagA+ H. pylori respectively.

RESULTS

9 studies involving 3033 subjects (1083 pancreatic cancer cases, 1950 controls) were included. Summary OR and 95%CI of the overall meta-analysis of all included studies were 1.47 and 1.22-1.77, pooled data of the 4 high-quality studies were OR 1.28, 95%CI 1.01-1.63. OR of the 5 studies examined CagA+ strains was 1.42, corresponding 95%CI was 0.79 to 2.57. Summary estimates of subgroup analysis based on regional distribution are as follows, Europe group: OR 1.56, 95%CI 1.15-2.10; East Asia group: OR 2.01, 95%CI 1.33-3.02; North America group: OR 1.17, 95%CI 0.87-1.58. There was not obvious heterogeneity across the 9 studies. No publication bias was detected.

CONCLUSION

H. pylori infection is significantly, albeit weakly, associated with pancreatic cancer development. The association is prominent in Europe and East Asia, but not in North America. CagA+ H. pylori strains appear not to be associated with pancreatic cancer. However, more studies, especially prospective studies, are needed to validate our results.

Gastric exocrine and endocrine cell morphology under prolonged acid inhibition therapy: results of a 5-year follow-up in the LOTUS trial

BACKGROUND

Sustained acid inhibition with PPI stimulates gastrin secretion, exerting a proliferative drive on enterochromaffin-like cells (ECL cells) of the oxyntic mucosa. It may also accelerate development of gastric gland atrophy in Helicobacter pylori-infected individuals.

AIMS

To evaluate gastric exocrine and endocrine cell changes in GERD patients randomised to laparoscopic antireflux surgery (LARS, n = 288) or long-term (5 years) esomeprazole (ESO) treatment (n = 266).

METHODS

Antral and corpus biopsies were taken at endoscopy and serum gastrin and chromogranin A levels were assayed, at baseline and after 1, 3 and 5 years' therapy.

RESULTS

Biopsies were available at each time point for 158 LARS patients and 180 ESO patients. In H. pylori-infected subjects, antral mucosal inflammation and activity improved significantly (P < 0.001) and stabilised after 3 years on esomeprazole while no change in inflammation was observed after LARS. Oxyntic mucosal inflammation and activity remained stable on esomeprazole but decreased slightly over time after LARS. Neither intestinal metaplasia nor atrophy developed in the oxyntic mucosa. ECL cell density increased significantly after ESO (P < 0.001), corresponding with an increase in circulating gastrin and chromogranin A. After LARS, there was a significant decrease in ECL cell density (P < 0.05), accompanied by a marginal decrease in gastrin and chromogranin.

CONCLUSIONS

Antral gastritis improved in H. pylori-infected GERD patients after 5 years on esomeprazole, with little change in laparoscopic antireflux surgery patients, who acted as a control. Despite a continued proliferative drive on enterochromaffin-like cells during esomeprazole treatment, no dysplastic or neoplastic lesions were found and no safety concerns were raised. NCT 00251927.

Helicobacter felis--associated gastric disease in microbiota-restricted mice

Human Helicobacter pylori infection leads to multiple pathological consequences, including gastritis and adenocarcinoma. Although this association has led to the classification of H. pylori as a type 1 carcinogen, it is not clear if additional nonhelicobacter gastric microbiota play a role in these diseases. In this study, we utilized either specific pathogen-free C57BL/6 mice (B6.SPF) or mice colonized with altered Schaedler flora (B6.ASF) to evaluate the role of nonhelicobacter gastric microbiota in disease development after Helicobacter felis infection. Despite similar histological changes, H. felis persisted in B6.ASF stomachs, while H. felis could no longer be detected in the majority of B6.SPF mice. The B6.SPF mice also acquired multiple Lactobacillus spp. in their stomachs after H. felis infection. Our data indicate that potential mechanisms responsible for the ineffective H. felis clearance in the B6.ASF model include the absence of new gastric microbiota to compete for the gastric niche, the lack of expression of new gastric mucins, and a reduced ratio of H. felis-specific IgG2c:IgG1 serum antibodies. These data suggest that although H. felis is sufficient to initiate gastric inflammation and atrophy, bacterial eradication and the systemic immune response to infection are significantly influenced by pre-existing and acquired gastric microbiota.

Association between Helicobacter pylori seropositivity and digestive tract cancers

AIM

To explore the role of Helicobacter pylori (H pylori) infection on the risk of digestive tract cancers.

METHODS

In total, 199 oral squamous-cell carcinoma (SCC), 317 esophageal SCC, 196 gastric cardia and non-cardia adenocarcinoma and 240 colon adenocarcinoma patients were recruited for serum tests of H pylori infection. Two hospital- and one community-based control groups were used for the comparisons. H pylori seropositivity was determined by an enzyme linked immunosorbent assay method against H pylori IgG.

RESULTS

Presence of H pylori infection was significantly inversely associated with esophageal SCC [adjusted odds ratio (AOR): 0.315-0.472, all P-value < 0.05] but positively associated with gastric adenocarcinoma (both cardia and non-cardia) (AOR: 1.636-3.060, all P-value < 0.05) in comparison to the three control groups. Similar results were not found in cancers of the oral cavity and colon.

CONCLUSION

Our findings support the finding that H pylori seropositivity is inversely associated with esophageal SCC risk, but increases the risk of gastric cardia adenocarcinoma.

Molecular characterization of the stomach microbiota in patients with gastric cancer and in controls

Persistent infection of the gastric mucosa by Helicobacter pylori can initiate an inflammatory cascade that progresses into atrophic gastritis, a condition associated with reduced capacity for secretion of gastric acid and an increased risk of developing gastric cancer. The role of H. pylori as an initiator of inflammation is evident but the mechanism for development into gastric cancer has not yet been proven. A reduced capacity for gastric acid secretion allows survival and proliferation of other microbes that normally are killed by the acidic environment. It has been postulated that some of these species may be involved in the development of gastric cancer; however, their identities are poorly defined. In this study, the gastric microbiota from ten patients with gastric cancer was characterized and compared with that from five dyspeptic controls using the molecular profiling approach terminal restriction fragment length polymorphism (T-RFLP), in combination with 16S rRNA gene cloning and sequencing. T-RFLP analysis revealed a complex bacterial community in the cancer patients that was not significantly different from that in the controls. Sequencing of 140 clones revealed 102 phylotypes, with representatives from five bacterial phyla (Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria). The data revealed a relatively low abundance of H. pylori and showed that the gastric cancer microbiota was instead dominated by different species of the genera Streptococcus, Lactobacillus, Veillonella and Prevotella. The respective role of these species in development of gastric cancer remains to be determined.

Macroscopic extent of gastric mucosal atrophy: increased risk factor for esophageal squamous cell carcinoma in Japan

Background

We aimed to estimate whether the macroscopic extent of gastric mucosal atrophy is associated with a risk for esophageal squamous cell carcinoma using a case-control study in Japanese subjects, a population known to have a high prevalence of CagA-positive H. pylori infection.

Methods

Two hundred and fifty-three patients who were diagnosed as having esophageal squamous cell carcinoma, and 253 sex- and age-matched controls were enrolled in the present study. The macroscopic extent of gastric mucosal atrophy was evaluated based on the Kimura and Takemoto Classification. A conditional logistic regression model with adjustment for potential confounding factors was used to assess the associations.

Results

Body gastritis, defined endoscopically, was independently associated with an increased risk for esophageal squamous cell carcinoma.

Conclusion

Our findings suggest that macroscopic body gastritis may be a risk factor for esophageal squamous cell carcinoma in Japan. Further studies are needed to confirm these findings.

Extensive gastric atrophy: an increased risk factor for superficial esophageal squamous cell carcinoma in Japan

OBJECTIVES

A recent study in Sweden has reported that gastric atrophy is associated with an increased risk for esophageal squamous cell carcinoma. However, this finding needs to be confirmed in other ethnic groups due to the wide geographic variation of this cancer.

OBJECTIVES

To investigate whether gastric atrophy is associated with a risk for esophageal squamous cell carcinoma using a case-control study in Japanese subjects, a population known to have a high prevalence of H. pylori infection and accompanying gastric atrophy.

METHODS

Seventy-three patients who had undergone endoscopic mucosal resection for superficial esophageal squamous cell carcinoma, and 73 sex- and age-matched controls, were enrolled prospectively. Gastric fundic atrophy was evaluated by histology of biopsy specimens and serum pepsinogen I level (cutoff level 25 ng/mL). Conditional logistic regression model with adjustment for potential confounding factors was used to assess the associations.

RESULTS

Gastric atrophy, defined histologically or serologically, was independently associated with an increased risk for esophageal squamous cell carcinoma and the risk seemed to increase with the progression of the atrophy. Multivariate odds ratio (95% confidence interval) for histological fundic atropy, fundic intestinal metaplasia, and serological atrophy are 4.2 (1.5-11.7), 10.7 (2.3-50.4), and 8.2 (2.2-30.4), respectively.

CONCLUSIONS

Gastric atrophy, a newly recognized risk factor for esophageal squamous cell carcinoma in Sweden, is likely to be a risk factor in other areas. Further studies are warranted to explore the causal relationship.

The risk of pancreatic cancer in patients with gastric or duodenal ulcer disease

Although Helicobacter pylori (H. pylori) seropositivity is linked to an excess risk of pancreatic cancer, the biologic mechanism is unknown. Gastric ulcer is primarily associated with corpus colonization of H. pylori, atrophic gastritis and formation of N-nitrosamines. Duodenal ulcer is a marker of antral colonization, hyperacidity and uninhibited secretin release. We estimated relative risks for pancreatic cancer among patients with gastric or duodenal ulcer, based on a register-based retrospective cohort study with 88,338 patients hospitalized for gastric ulcer and 70,516 patients for duodenal ulcer recorded in the Swedish Inpatient Register between 1965 and 2003. Following operation, the 14,887 patients who underwent gastric resection and 8,205 with vagotomy were analyzed separately. Multiple record-linkages allowed complete follow-up and identification of all incident cases of pancreatic cancer until December 31, 2003. Standardized incidence ratios (SIRs) estimated relative risks. During years 3-38 of follow-up, we observed a 20% excess risk (95% confidence interval [CI] 10-40%) for pancreatic cancer among unoperated gastric ulcer patients. The excess increased to 50% (95% CI 10-110%) 15 years after first hospitalization (p for trend = 0.03). SIR was 2.1 (95% CI 1.4-3.1) 20 years after gastric resection. Unoperated duodenal ulcer was not associated with pancreatic cancer risk, nor was vagotomy. Our results lend indirect support to the nitrosamine hypothesis, but not to the hyperacidity hypothesis in the etiology of pancreatic cancer.

Non-Helicobacter bacterial flora rarely develops in the gastric mucosal layer of children

Non-Helicobacter bacteria can be cultured from the gastric mucosa in adults but in children, there are no studies about such microflora. The purpose of this study, therefore, was to clarify whether gastric biota develops in children. In 10 children and 10 adults or elderly (5 H. pylori-infected and 5 uninfected in each group), biopsy specimens of the gastric antrum and corpus and gastric juice were studied for bacterial examinations and the data were compared between both age groups in relation to H. pylori status and luminal pH. Bacterial genera and species were analyzed using both culture and real-time polymerase chain reaction (PCR) with the 52 genus- and species-specific primer sets. Non-Helicobacter bacteria in the mucosa were cultured from all adult patients, whereas microorganisms were cultured in only one child (p < .001). Gastric pH was lower in children (median, 1.4) than in adults (median, 2.6) (p < .005). The grade of endoscopic gastric atrophy was moderate or severe in 8 adults, but absent or mild in all 10 children. Among adults, there was a significant positive correlation between gastric pH and total bacterial counts of both the mucosa and juice. These data indicate that impaired gastric acid secretion associated with long-term H. pylori infection enables non-Helicobacter bacteria to colonize in the human stomach. Such microorganisms rarely colonize in the gastric mucosa in children regardless of H. pylori status.

Changes of gastric mucosal architecture during long-term omeprazole therapy: results of a randomized clinical trial

BACKGROUND

The impact of long-term acid suppression on the gastric mucosa remains controversial.

AIM

To report further observations on an established cohort of patients with gastro-oesophageal reflux disease, after 7 years of follow-up.

METHODS

Of the original cohort randomized to either antireflux surgery or omeprazole, 117 and 98 patients remained in the medical and surgical arms, respectively. Gastric biopsies were taken at baseline and throughout the study.

RESULTS

Fifty-three antireflux surgery and 39 omeprazole-treated patients had Helicobacter pylori infection at randomization. Eighty-three omeprazole-treated and 60 antireflux surgery patients remained H. pylori negative over the 7 years, and no change was observed in mucosal morphology except for a change in endocrine cell population (linear and diffuse hyperplasia, P = 0.03). During the 7-year study many patients, who were initially H. pylori infected, had the infection eradicated leaving only 13 omeprazole and 12 antireflux surgery patients still infected. In these patients, omeprazole induced a deterioration of the mucosal inflammation scores (P = 0.01) with a numerical increase of glandular atrophy.

CONCLUSIONS

Long-term omeprazole therapy does not alter the exocrine oxyntic mucosal morphology in H. pylori-negative patients, but mucosal endocrine cells appear to be under proliferative stimulation; in H. pylori-positive patients there are changes in mucosal inflammation and atrophy.

Mechanisms of Disease: inflammation and the origins of cancer

Many common cancers develop as a consequence of years of chronic inflammation. Increasing evidence indicates that the inflammation may result from persistent mucosal or epithelial cell colonization by microorganisms; including hepatitis B virus and hepatitis C virus, which can cause hepatocellular cancer; human papilloma virus subtypes, which cause cervical cancer, and the bacterium Helicobacter pylori, which can cause gastric cancer. At present, the cause of other chronic inflammatory conditions associated with increased cancer risk, such as ulcerative colitis, is obscure. Particular microbial characteristics as well as the type of the inflammatory response contribute to clinical outcomes via influence on epithelial cell and immune responses. Persistent inflammation leads to increased cellular turnover, especially in the epithelium, and provides selection pressure that result in the emergence of cells that are at high risk for malignant transformation. Cytokines, chemokines, free radicals, and growth factors modulate microbial populations that colonize the host. Thus, therapeutic opportunities exist to target the causative microbe, the consequent inflammatory mediator, or epithelial cell responses. Such measures could be of value to reduce cancer risk in inflammation-associated malignancies.

Helicobacter-induced intestinal metaplasia in the stomach correlates with Elk-1 and serum response factor induction of villin

Chronic Helicobacter pylori infection results in serious sequelae, including atrophy, intestinal metaplasia, and gastric cancer. Intestinal metaplasia in the stomach is defined by the presence of intestine-like cells expressing enterocyte-specific markers, such as villin. In this study, we demonstrate that villin is expressed in intestine-like cells that develop after chronic infection with H. pylori in both human stomach and in a mouse model. Transfection studies were used to identify specific regions of the villin promoter that are inducible by exposure of the cells to H. pylori. We demonstrated that induction of the villin promoter by H. pylori in a human gastric adenocarcinoma cell line (AGS) required activation of the Erk pathway. Elk-1 and the serum response factor (SRF) are downstream transcriptional targets of the Erk pathway. We observed inducible binding of Elk-1 and the SRF after 3 and 24 h of treatment with H. pylori, suggesting that the bacteria alone are sufficient to initiate a cascade of signaling events responsible for villin expression. Thus, H. pylori induction of villin in the stomach correlates with activation and cooperative binding of Elk-1 and the SRF to the proximal promoter of villin.

Helicobacter pylori infection and gastric atrophy: risk of adenocarcinoma and squamous-cell carcinoma of the esophagus and adenocarcinoma of the gastric cardia

BACKGROUND

An inverse association between Helicobacter pylori infection and esophageal adenocarcinoma has been reported that may be attributed to reduced acidity from inducing atrophic gastritis and from producing ammonia. We examined associations between H. pylori infection, gastric atrophy, and the risk of esophageal adenocarcinoma, esophageal squamous-cell carcinoma, and gastric cardia adenocarcinoma in a large population-based case-control study in Sweden.

METHODS

Self-reported data were obtained during interviews, and serum was collected from 97 patients with incident esophageal adenocarcinoma, 85 patients with incident esophageal squamous-cell carcinoma, 133 patients with incident gastric cardia adenocarcinoma, and 499 randomly selected control subjects. Serum antibodies against whole H. pylori cell-surface antigens (HP-CSAs) and cytotoxin-associated gene A (CagA) antigens were assessed by an IgG enzyme-linked immunosorbent assay and immunoblotting, respectively. Gastric atrophy was assessed by serum levels of pepsinogen I. Multivariable logistic regression with adjustment for potential confounding factors was used to evaluate associations.

RESULTS

H. pylori infection, assayed by HP-CSA or CagA antibodies, was statistically significantly associated with a reduced risk for esophageal adenocarcinoma (for HP-CSA antibodies, odds ratio [OR] = 0.3, 95% confidence interval [CI] = 0.2 to 0.6; for CagA antibodies, OR = 0.5, 95% CI = 0.3 to 0.8; for both, OR = 0.2, 95% CI = 0.1 to 0.5). Gastric atrophy was not associated with the risk for esophageal adenocarcinoma (OR = 1.1, 95% CI = 0.5 to 2.5). Serum CagA antibodies and gastric atrophy were associated with an increased risk for esophageal squamous-cell carcinoma (OR = 2.1, 95% CI = 1.1 to 4.0, and OR = 4.3, 95% CI = 1.9 to 9.6, respectively). The risk of gastric cardia adenocarcinoma was not associated with H. pylori infection. However, gastric atrophy was associated with an increased risk for gastric cardia adenocarcinoma (OR = 4.5, 95% CI = 2.5 to 7.8).

CONCLUSIONS

Infection with H. pylori may reduce the risk of esophageal adenocarcinoma, but it is unlikely to do so by atrophy-reduced acidity. Gastric atrophy and infection with CagA-positive strains of H. pylori may increase the risk for esophageal squamous-cell carcinoma.

Infiltration of neutrophils is required for acquisition of metastatic phenotype of benign murine fibrosarcoma cells: implication of inflammation-associated carcinogenesis and tumor progression

QR-32 tumor cells, a clone derived from a murine fibrosarcoma, are poorly tumorigenic and nonmetastatic when injected into syngeneic C57BL/6 mice. However, they are converted to highly malignant ones once they have grown in vivo after being co-implanted in a subcutaneous site with a foreign body, a gelatin sponge. Early phase of inflammation induced by the gelatin sponge participates in the conversion and histological analysis shows predominant infiltration of neutrophils. The objective of this study was to determine whether the depletion of the infiltrating neutrophils has any effect on the tumor progression. Intraperitoneal administration of a monoclonal anti-granulocyte antibody, RB6-8C5 (RB6), depleted neutrophils from both the peripheral blood circulation and the local inflamed site in mice with co-implantation of QR-32 tumor cells and gelatin sponge. The RB6 administration did not inhibit either tumor development or growth of QR-32 tumor cells. In contrast, tumor cell lines established from RB6-administered mice showed a significant decrease in metastatic incidence as compared with the tumor cell lines obtained from the mice with administration of control rat IgG or saline. Metastatic ability was significantly suppressed when RB6 had been administered in the early phase (from day -2 to day 6 after implantation); however, the administration in the middle (from day 6 to day 14) or late (from day 14 to day 22) phase did not affect the metastatic ability. We confirmed the phenomena by using integrin beta(2) knockout mice that had impaired neutrophil infiltration into inflamed sites. In the knockout mice, neutrophils hardly infiltrated into the gelatin sponge and the tumors showed dramatically suppressed metastatic phenotype as compared with those in wild-type mice or nude mice. Immunohistochemical analysis demonstrated that expressions of 8-hydroxy-2'-deoxyguanosine and nitrotyrosine were parallel to those in the presence of neutrophils. These results suggested that inflammation, especially when neutrophils infiltrate into tumor tissue, is primarily important for benign tumor cells to acquire metastatic phenotype.

Changes in gastric mucosa and luminal environment during acid-suppressive therapy: a review in depth

Acid-suppressive therapy and subsequent changes in gastric mucosa and luminal environment rank highly amongst the investigated issues in gastroenterology over the past two to three decades. Herewith, we present an overview of these intragastric changes, particularly during long-term administration of acid-suppresive medication and concurrent infection with Helicobacter pylori. Current evidence indicates that: i) Long-term acid suppression facilitates the development of fundic ECL cell hyperplasia, especially in the presence of Helicobacter pylori. No neoplastic changes directly attributable to acid suppression have so far been demonstrated in humans. ii) Acid-suppressive therapy increases the risk of enteric infections. iii) Acid-suppressive therapy does not alter fat and mineral bioavailability, but may decrease the absorption of protein-bound vitamin B12. iv) Acid suppression invariably results in intragastric overgrowth of non-Helicobacter pylori bacterial species. The concurrent infection with Helicobacter pylori may promote this bacterial overgrowth and the intragastric formation of N-nitrosamines. v) Acid-suppressive therapy alters the natural course of Helicobacter pylori gastritis, transforming the antral-predominant pattern into a body-predominant pattern, which in turn may progress to body gland atrophy. The pathophysiology of this phenomenon is currently under investigation. vi) In view of the potential adverse effects of acid suppression in the presence of Helicobacter pylori, the screen-and-treat strategy is advocated for Helicobacter pylori in subjects considered for long-term treatment.

Alterations in intragastric nitrite and vitamin C levels during acid inhibitory therapy

Most nitrite entering the healthy acid-secreting stomach is derived from dietary nitrate. The latter is absorbed from the small intestine, 25% then being secreted by the salivary glands into the mouth. Buccal organisms subsequently convert 20% of this nitrate to nitrite. When this nitrite is swallowed, the ascorbic acid in the acidic gastric juice reduces it to nitric oxide, which is absorbed by the mucosa. In the process, the ascorbic acid is oxidized to dehydroascorbic acid. When the intragastric pH is elevated by powerful anti-secretory agents, this gastric chemistry is profoundly modified. At a neutral pH, the swallowed nitrite does not react with ascorbic acid but accumulates in the stomach. The level of nitrite in the gastric juice during treatment with anti-secretory medication is particularly high after a nitrate-containing meal. Powerful anti-secretory medication also lowers the intragastric concentration of ascorbic acid and total vitamin C, probably because of the relative instability of the vitamin at a higher pH. These changes in the intragastric concentrations of nitrite and ascorbic acid are most marked in Helicobacter pylori -infected subjects on proton pump inhibitor therapy. It is recognized that an elevated nitrite-to-ascorbic acid ratio predisposes to the formation of potentially carcinogenic N -nitroso compounds. It is, however, unclear at present whether such compounds are formed within the human stomach.

Non-Helicobacter pylori bacterial flora during acid-suppressive therapy: differential findings in gastric juice and gastric mucosa

BACKGROUND

Intragastric growth of non-Helicobacter pylori bacteria commonly occurs during acid-suppressive therapy. The long-term clinical consequences are still unclear.

AIM

To investigate the luminal and mucosal bacterial growth during gastric acid inhibition, in relation to the type and duration of acid-inhibitory treatment, as well as to concomitant H. pylori infection.

METHODS

A total of 145 patients on continuous acid inhibition with either proton pump inhibitors (n=109) or histamine2-receptor antagonists (H(2)RAs, n=36) for gastro-oesophageal reflux disease, and 75 dyspeptic patients without acid inhibition (control group) were included. At endoscopy, fasting gastric juice was obtained for pH measurement and bacteriological culture. Gastric biopsy specimens were examined for detection of H. pylori (immunohistochemistry) and of non-H. pylori bacteria (modified Giemsa stain-positive and immunohistochemistry-negative at the same location).

RESULTS

Non-H. pylori flora was detected in the gastric juice of 92 (41.8%) patients and in the gastric mucosa of 109 (49.6%) patients. In gastric juice, prevalence rate for non-H. pylori bacteria was higher in patients taking proton pump inhibitors than controls and those taking H(2)RAs (58.7% vs. 22.6% and vs. 30.6%, P < 0.0001 and P < 0.003, respectively), but did not differ statistically between H(2)RAs and controls. In gastric mucosa, prevalence rates for non-H. pylori bacteria were higher in patients taking proton pump inhibitors and H(2)RAs than in the controls (antrum: 46.9% and 48.6% vs. 25%, P < 0.05 for both; corpus: 52.2% and 56.8% vs. 23.7%, P < 0.001 for both), but did not differ between proton pump inhibitors and H(2)RAs. Both luminal and mucosal growth of non-H. pylori bacteria were significantly greater in H. pylori-positive than -negative patients taking proton pump inhibitors (P < 0.05 for both). Luminal growth of non-H. pylori flora increased with the intragastric pH level, whilst mucosal bacterial growth increased with the duration of acid inhibition.

CONCLUSIONS

Non-H. pylori flora not only contaminates the gastric juice but also colonizes the gastric mucosa of a large proportion of patients treated long-term with acid inhibition. The relationship between H. pylori and non-H. pylori bacteria in the pathogenesis of atrophic gastritis and gastric cancer needs further elucidation.

Omeprazole, Helicobacter pylori status, and alterations in the intragastric milieu facilitating bacterial N-nitrosation

BACKGROUND & AIMS

Omeprazole produces greater acid inhibition in Helicobacter pylori-positive than -negative subjects. We investigated whether this is accompanied by more profound changes in the intragastric milieu that facilitates bacterial synthesis of N-nitroso compounds.

METHODS

Gastric juice pH; nitrite, ascorbic acid, and total vitamin C concentrations; and colonization by other bacteria were examined before and during omeprazole treatment in subjects with and without H. pylori infection. Studies were performed in the fasting state and after consumption of 2 mmol nitrate (equivalent to a salad meal).

RESULTS

Before omeprazole, H. pylori-positive and -negative subjects were similar for all parameters. During omeprazole, H. pylori-positive subjects had a higher intragastric pH (7.8 vs. 3.0; P < 0.00001) and greater colonization with non-H. pylori species (5 x 10(7) vs. 5 x 10(5) CFU/mL; P < 0.05). These bacteria included nitrosating species. During omeprazole treatment, H. pylori-positive subjects had higher intragastric nitrite levels after the nitrate meal (median area under the concentration/time curve, 12,450 vs. 4708 micromol/L. min; P = 0.04). Omeprazole lowered intragastric vitamin C levels in H. pylori-positive but not -negative subjects (1.8 vs. 3.4 microg/mL, respectively; P = 0.02).

CONCLUSIONS

In H. pylori-positive subjects, omeprazole produces disturbances in intragastric nitrite, vitamin C, and bacterial colonization that facilitate bacterial N-nitrosation. This may place them at increased risk of mutagenesis and carcinogenesis.

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.

Helicobacter pylori. One bacterium and a broad spectrum of human disease! An overview

Since the historical rediscovery of gastric spiral Helicobacter pylori in the gastric mucosa of patients with chronic gastritis by Warren and Marshall in 1983, peptic ulcer disease has been largely viewed as being of infectious aetiology. Indeed, there is a strong association between the presence of H. pylori and chronic active gastritis in histology. The bacterium can be isolated in not less than 70% of gastric and in over 90% of duodenal ulcer patients. Eradication of the organism has been associated with histologic improvement of gastritis, lower relapse rate and less risk of bleeding from duodenal ulcer. The bacterium possesses several virulence factors enabling it to survive the strong acid milieu inside the stomach and possibly damaging host tissues. The sequence of events by which the bacterium might cause gastric or duodenal ulcer is still not fully elucidated and Koch's postulates have never been fulfilled. In the majority of individuals, H. pylori infection is largely or entirely asymptomatic and there is no convincing data to suggest an increase in the prevalence of peptic ulcer disease among these subjects. An increasingly growing body of literature suggests an association between colonization by H. pylori in the stomach and a risk for developing gastric mucosa-associated lymphoid tissue (MALT), MALT lymphoma, gastric adenocarcinoma and even pancreatic adenocarcinoma. The bacterium has been implicated also in a number of extra-gastrointestinal disorders such as ischaemic heart disease, ischaemic cerebrovascular disease, atherosclerosis, and skin diseases such as rosacea, but a causal role for the bacterium is missing. Eradication of H. pylori thus seems to be a beneficial impact on human health. Various drug regimens are in use to eradicate H. pylori involving the administration of three or four drugs including bismuth compounds, metronidazole, clarithromycin, tetracyclines, amoxycillin, ranitidine, omeprazole for 1-2 weeks. The financial burden, side effects and emergence of drug resistant strains due to an increase in the use in antibiotics for H. pylori eradication therapy need further reconsideration.

Neutrophils, nitric oxide synthase, and mutations in the mutatect murine tumor model

Mutatect MN-11 is a tumor line that can be grown subcutaneously in syngeneic C57BL/6 mice. The frequency of spontaneously arising mutants at the hypoxanthine phosphoribosyltransferase (Hprt) locus was observed to be elevated as a result of in vivo growth. The objective of the present study was to identify factors in the tumor microenvironment that might explain this increase in mutant frequency (MF). When tumors were examined histologically, neutrophils were found to be the predominant infiltrating cell type. Quantitative estimates of the number of neutrophils and MF of tumors in different animals revealed a statistically significant correlation (r = 0.63, P < 0.0001). Immunohistochemical analysis for inducible nitric oxide synthase (iNOS) demonstrated its presence, mainly in neutrophils. Biochemical analysis of tumor homogenates for nitric oxide synthase (NOS) activity indicated a statistically significant correlation with MF (r = 0.77, P < 0.0001). Nitrotyrosine was detected throughout the tumor immunohistochemically; both cytoplasmic and nuclear staining was seen. To increase the number of infiltrating neutrophils, tumors were injected with chemoattractant interleukin-8 and prostaglandin E2. This produced a statistically significant increase in neutrophil content (P = 0.005) and MF (P = 0.0002). As in control MN-11 tumors, neutrophil content and MF were strongly correlated (r = 0.63, P = 0. 003). Because neutrophils are a potential source of genotoxic reactive oxygen and/or nitrogen species, our results support the notion that these tumor-infiltrating cells may be mutagenic and contribute to the burden of genetic abnormalities associated with tumor progression.

The interrelationship between Helicobacter pylori vacuolating cytotoxin and gastric carcinoma

OBJECTIVE

We aimed to determine whether cytotoxin-positive Helicobacter pylori strains are associated with gastric carcinoma.

METHODS

We studied 130 patients: 57 H. pylori-positive patients with gastric carcinoma, 53 H. pylori-positive patients without gastric carcinoma, and 20 H. pylori-negative subjects. The ability of H. pylori strains to produce vacuolating cytotoxin was tested in INT-407 and HeLa cells. The presence of antibodies to cytotoxin was investigated in blood serum from all subjects by immunoblotting. Fragments of the gastric mucosa from patients without gastric carcinoma and H. pylori-negative subjects were obtained for histopathological study.

RESULTS

Considering the results as a whole, 40 (70.2%) patients with and 22 (41.5%) without gastric carcinoma were colonized by cytotoxin-positive strains. Antibodies against cytotoxin were not observed in the serum from 17 (29.8%) gastric carcinoma patients and from 31 (58.5%) patients without gastric carcinoma. H. pylori strains isolated from these patients did not produce cytotoxin in vitro. In regard to cytotoxin positivity, a significant difference was observed between patients with and without gastric carcinoma (p=0.004; odds ratio [OR]: 3.3; 95% confidence interval [CI]: 1.4-7.9). Higher scores of mononuclear (p=0.0001) and polymorphonuclear (p=0.000003) cells were observed in the antral mucosa from H. pylori-positive patients without gastric carcinoma infected by cytotoxin-positive strains than in those harboring cytotoxin-negative strains.

CONCLUSION

Cytotoxin-producing H. pylori strains were more frequently observed in patients with gastric carcinoma and this aspect emphasizes the role of cytotoxin in the genesis of the tumor.

In vitro susceptibility of Helicobacter pylori to protolichesterinic acid from the lichen Cetraria islandica

With reference to the traditional use of Cetraria islandica (Iceland moss) for relief of gastric and duodenal ulcer, plant extracts were screened for in vitro activity against Helicobacter pylori. (+)-Protolichesterinic acid, an aliphatic alpha-methylene-gamma-lactone, was identified as an active component. The MIC range of protolichesterinic acid, in free as well as salt form, was 16 to 64 micrograms/ml.

Effect of nizatidine 300 mg at night and omeprazole 20 mg in the morning on 24-hour intragastric pH and bacterial overgrowth in patients with acute duodenal ulcer

The study investigated the effect of either nocturnal acid suppression by the H2 antagonist nizatidine 300 mg at night or prolonged acid suppression by the proton- pump inhibitor omeprazole 20 mg in the morning, during four weeks, on intragastric pH profile, occurrence of bacterial growth in gastric fluid and biopsies, and healing rate in 23 patients with an acute duodenal ulcer. The endoscopic healing rate did not differ significantly between the two treatment modalities. The 24-hr acid secretion was significantly more reduced by omeprazole than nizatidine (P < 0.002). After treatment by nizatidine and omeprazole, respectively, median 24-hr intragastric pH increased from 1.5 to 1.8 (P < 0.01) and from 1.5 to 6.1 (P < 0.01), respectively. Nighttime acid inhibition did not differ significantly. The difference in gastric bacterial colonization after either omeprazole or nizatidine did not reach significance. However, median 24-hr pH and the fraction of the day with pH < 3 and pH < 4 were significantly correlated to bacterial colonization of the gastric fluid (P < 0.05).

Quality of life: a reflection of symptoms and concerns

BACKGROUND

Upper gastrointestinal complaints are common in the general population. Most patients consulting have no or only minimal markers of disease. It is important to evaluate new methods for the assessment and follow-up of treatment of these new patient groups.

METHODS AND RESULTS

Recent publications on Quality of Life (QOL) and upper gastrointestinal disease are reviewed with the specific aim of relating the effect of disease symptoms and patient concerns to the outcome of investigations. We found that QOL is adversely affected in upper gastrointestinal disorders and that effective treatment medically or surgically normalizes the scores. There is a good correlation between degree of symptoms and QOL outcome. Patients' concern affects the outcome.

CONCLUSION

QOL assessments are helpful in evaluating the impact of upper gastrointestinal disease.

Twenty-four-hour intragastric acidity: 300 mg ranitidine b.d., 20 mg omeprazole o.m., 40 mg omeprazole o.m. vs. placebo

BACKGROUND

There is considerable controversy about the degree of acid suppression that is optimal for the treatment of peptic disorders.

AIM

To compare the effects of three different regimens that are reported to strongly inhibit acid secretion.

METHODS

Intragastric 24-hour pH monitoring was performed in 11 healthy subjects in a randomized, multiple, cross-over, double-blind study. Each subject received four dose regimens, each for 2 weeks, in a random order. The regimens were: 300 mg ranitidine b.d., 20 mg omeprazole o.m., 40 mg omeprazole o.m., and placebo.

RESULTS

The decrease in gastric acidity during the daytime and during the total 24-hour period by all three treatments was significantly greater than after placebo; a significant difference in acid inhibition was found between ranitidine and 40 mg omeprazole, but not between ranitidine and 20 mg omeprazole, nor between the two doses of omeprazole. During the night-time the decrease in gastric acidity by all three treatments was significantly greater than after placebo; no difference was seen between the two doses of omeprazole and ranitidine. For the time of pH greater than 3 we found no statistical difference between the various acid decreasing regimens. The pH remained significantly longer above 4 after ranitidine and the two doses of omeprazole compared with placebo, and also longer above 4 after 40 mg omeprazole compared with ranitidine, but not after 20 mg omeprazole compared with ranitidine, nor after the two different doses of omeprazole.

CONCLUSIONS

Dosing with 300 mg ranitidine b.d., 20 mg omeprazole or 40 mg omeprazole is superior in gastric acid inhibition compared with placebo, when measured using 24-hour pH monitoring.