Helicobacter pylori infection: independent risk indicator of gastric adenocarcinoma

Helicobacter pylori and gastric cancer in Croatia

The seroprevalence of Helicobacter pylori infection was studied in a population from two areas of Croatia with significantly different average gastric cancer (GC) cumulative incidence and mortality rates. In a random sample of 456 blood sera from both areas, which was tested with the ELISA Helicobacter pylori-antibody test, 48.8% of people in the north and 53.3% in the south of the country were found to be infected. The difference between the two areas in the seroprevalence of the infection was not statistically significant, nor did their populations differ in age, sex, educational background, smoking habit or wine consumption. Our results do not point to any association between the prevalence of Helicobacter pylori infection and the level of cumulative incidence and GC mortality levels.

Screening for gastric cancer by Helicobacter pylori serology: a retrospective study

BACKGROUND

Screening by serology for Helicobacter pylori in young dyspeptic patients has been shown to be effective in reducing demand for endoscopy. H. pylori has been implicated in the causation of gastric cancer and the reported seropositivity rate in patients with gastric cancer ranges from 69 to 94 per cent. The aim of this study was to assess the potential value of Helicobacter antibodies as a method of selecting dyspeptic patients over the age of 45 years for endoscopy.

METHODS

A retrospective comparison of the antibody status to H. pylori was made between 154 patients with gastric cancer and a sex- and date of birth-matched dyspeptic control group. Results from the former group were correlated with demographic data and tumour characteristics.

RESULTS

Significantly more patients with gastric cancer were seropositive than controls (77 versus 66 per cent). H. pylori was not related to the Laurén classification of the tumour. Tumour site was significant: body and antrum tumours were associated with Helicobacter whereas cardial tumours appeared to be unrelated.

CONCLUSION

Screening by antibody assays to H. pylori would miss more than 30 per cent of current gastric cancers. The increasing incidence of cardial cancer would cause this percentage to rise in the future.

Helicobacter pylori: from art to a science

Helicobacter pylori infection is widely prevalent especially in developing countries. Increasing knowledge of the pathophysiology associated with H. pylori is leading to an understanding of the mechanisms of mucosal inflammation and gastritis and how this leads to peptic ulcer disease, gastric mucosal associated lymphoid tissues (MALT), lymphoma and gastric cancer. More accurate diagnostic testing for the infection is now possible with both endoscopic and non-endoscopic tests to identify patients most appropriate for eradication therapy. Modern treatments tend to overcome the problems of metronidazole resistance and compliance seen with two week bismuth triple therapy and widely studied is a proton pump inhibitor given with clarithromycin and amoxicillin or metronidazole for one week. These achieve amongst the highest eradication rates and have also been shown to be cost effective. This paper reviews these recent advances and addresses areas of clinical interest and future directions.

Use of a gastric juice-based PCR assay to detect Helicobacter pylori infection in culture-negative patients

A gastric juice-based PCR assay was compared with culture, microscopy, and a rapid urease test with specimens from 114 subjects. The PCR and conventional tests were positive for 76 and 62% of the subjects, respectively. The prevalence of gastroduodenal disease and seropositivity for anti-Helicobacter pylori immunoglobulin G were similarly high among conventional-test-positive and PCR-only-positive subjects compared to all-negative ones. The PCR assay is recommended to confirm the H. pylori status of culture-negative peptic-ulcer patients.

Histological diagnosis of Helicobacter pylori gastritis is predictive of a high risk of gastric carcinoma

Chronic Helicobacter pylori infection has been identified as a major risk factor for the subsequent development of gastric carcinoma On the basis of seroepidemiological studies the relative risk for infected persons was estimated to range between 3 and 6. Our study attempted to determine the relative risk of gastric carcinoma in H. pylori-infected individuals based on the histological evaluation of gastritis in gastric carcinoma patients in the light of a declining prevalence of H. pylori infection in Western countries. We histologically determined the H. pylori infection rate in 215 patients with early gastric carcinoma (tumor stage pT1), and compared it with that of 215 asymptomatic persons matched by age and sex who were tested by the 13C urea breath test. On the basis of these data an odds ratio of 16.7 (CI 9.6-29.1) was calculated for the relative risk of developing gastric carcinoma in H. pylori-infected people. The histological diagnosis of gastritis permits a separate risk assessment for patients with autoimmune gastritis, and by excluding these patients from the analysis we calculated an odds ratio for H. pylori-infected persons of 150 (CI 36.4-622.9). The endoscopic-histological diagnosis of H. pylori infection is associated with an increased risk of the subsequent development of gastric carcinoma of approximately 150-fold compared with H. pylori-negative patients who do not have chronic atrophic corpus gastritis of the autoimmune type (type A gastritis).

Association between Helicobacter pylori and gastric carcinoma in the city of Malmö, Sweden. A prospective study

BACKGROUND

We have investigated the association between Helicobacter pylori and gastric carcinoma through a nested case-control study in a single city.

METHODS

From a cohort of 32,906 residents recruited from 1974 through 1992, 56 cases of gastric adenocarcinoma and 224 matched controls were selected. The mean interval between serum collection and diagnosis was 5.7 years. Frozen serum or plasma samples were analysed for IgG antibodies against H. pylori with an enzyme-linked immunosorbent assay.

RESULTS

The overall seropositivity prevalence in gastric cancer cases was 82%, compared with 49% in controls, giving an odds ratio (OR) of 5.0 (95% confidence interval (CI), 2.2-11.5). Partial gastrectomy because of peptic ulcer 5 to 36 year before diagnosis of gastric cancer could be a confounding factor. With exclusion of 10 such cases, H. pylori seropositivity among cases was 78%, as compared with 50% in matched controls (OR, 3.9; 95% CI, 1.7-9.2). Tumours of the cardia were not associated with H. pylori (OR, 0.92; 95% CI, 0.23-3.7), which is in contrast to tumours of the fundus, corpus, and antrum, which were significantly associated (OR, 11.1; 95% CI, 2.4-71.8). This difference in location was significant (P < 0.01).

CONCLUSION

There is a significant association between prior infection with H. pylori and later development of gastric carcinoma, and the association is related to noncardia gastric cancer.

Use of pulsed-field gel electrophoresis to determine genomic diversity in strains of Helicobacter hepaticus from geographically distant locations

In 1992 a helical microorganism associated with chronic active hepatitis and a high incidence of hepatocellular tumors was identified in the hepatic parenchyma of A/JCr mice. By using biochemical tests, phenotypic characterization, and 16S rRNA gene sequence analysis, the organism was classified as a novel Helicobacter species and named Helicobacter hepaticus. Recent surveys completed in our laboratory indicate that H. hepaticus is widespread in academic and commercial mouse colonies. The aim of this study was to examine the H. hepaticus genome by pulsed-field gel electrophoresis (PFGE) to determine the degree of genomic variation and genomic size. This technique has been used to identify significant genomic diversity among strains of Helicobacter pylori and to demonstrate only slight genomic diversity among strains of Helicobacter mustelae. Genomic DNAs from 11 isolates of H. hepaticus from the United States, Germany, France, and The Netherlands were subjected to PFGE after digestion with SmaI. Isolates from three independent sources within the United States had very similar PFGE patterns, suggesting that the genomic DNAs of these isolates are conserved. Genomic DNA isolated from a fourth source within the United States had a PFGE pattern different from those of the other U.S. isolates. Isolates obtained from Germany, France, and The Netherlands had PFGE patterns that differed markedly from those of the U.S. isolates and from one another. The use of DNA fingerprinting may be useful in subsequent epidemiological studies of H. hepaticus when the source and method of spread of this murine pathogen need to be ascertained. By PFGE, the genomic size of H. hepaticus is estimated to be roughly 1.3 Mb, which compares to 1.67 Mb for H. pylori and 1.7 Mb for H. mustelae.

Endoscopy is not a risk factor for Helicobacter pylori infection--but medical practice is

BACKGROUND

Previous studies have suggested an increased risk for Helicobacter pylori infection in physicians who perform UGI endoscopy because of exposure to potentially infectious gastric secretions. Therefore, the H. pylori infection status of the endoscopy staff was compared with the H. pylori prevalence of medical staff without endoscopy experience and control subjects who had no contact with patients.

METHODS

The noninvasive 13C-urea breath test was performed in 2108 volunteers: 1460 physicians (mean age 44 +/- 12 years), 235 nurses (33 +/- 10 years), and 413 control subjects (43 +/- 12 years) who were not working in clinical medicine. All subjects completed a questionnaire concerning the weekly frequency of gastroscopies and the duration of endoscopic experience.

RESULTS

Overall, 37.4% of the physicians and 35.3% of the nurses, but only 27.1% of the control subjects were infected. H. pylori infection was not significantly different between endoscopy-performing (37.8%; n = 1091) and general medical staff (35.9%; n = 604). Neither the frequency of gastroscopies nor the duration of endoscopy practice correlated with H. pylori status. With respect to the age distribution; however, a statistically significant higher prevalence of H. pylori was observed in physicians and nurses compared with the 413 control subjects without patient contact (p < 0.01).

CONCLUSION

UGI endoscopy is not a risk factor for H. pylori infection, but medical practice slightly raises H. pylori acquisition.

Helicobacter pylori may cause "reflux" gastritis after gastrectomy

Patients with "reflux" gastritis after gastrectomy suffer from a variety of symptoms, and this type of gastritis may sometimes compromise the quality of life of these patients. Since Helicobacter pylori is considered to be one of the most important pathogenetic factors in gastritis, the association between H. pylori and reflux gastritis was investigated in this study. A total of 145 patients with gastrectomy were entered into the study. Five biopsy specimens from the gastric remnant were taken at upper gastrointestinal endoscopy. One specimen was examined pathohistologically, and the remaining four were examined for H. pylori infection. Fifty-two patients (36%) demonstrated H. pylori infection. The prevalence of H. pylori was significantly higher in patients who had a partial gastrectomy, and it was significantly lower in patients who had undergone gastrectomy more than 4 years previously. The histologic gastritis score in patients with H. pylori infection was significantly higher. Furthermore, H. pylori was eradicated in patients with some symptoms of gastritis and no bile reflux to the residual stomach at endoscopy; in these patients the symptoms were relieved and the histologic gastritis score decreased significantly. In conclusion, possible involvement of H. pylori is suspected in the pathogenesis of "nonreflux" gastritis after gastrectomy.

Gastric cancer and Helicobacter pylori: a critical evaluation of the epidemiological evidence

Despite a dramatic reduction in incidence and mortality, gastric cancer (GC) still was recently reported to be the second most common neoplastic cause of death worldwide. GC treatment has not been improved substantially, and large-scale early diagnosis programs have not proved feasible outside Japan. On the other hand, even if diet has been shown to play a relevant role in the etiology of GC, primary prevention programs based on dietary modifications are difficult to implement, and results of human chemoprevention trials, although encouraging, have not been confirmed. Overall, the observed reduction in GC risk can reasonably be considered to be the result of a spontaneous trend, somehow related to the wide-spread improvements in socioeconomic conditions. Domestic refrigeration, an increased availability of fresh fruit and vegetables, and a reduced use of salt are considered to be the most relevant factors in explaining the decreasing temporal trend and the geographical patterns of GC. Recently, evidence of an association between Helicobacter pylori infection and GC has been provided by epidemiological studies, particularly three studies specifically designed as nested case-control studies in which blood samples were collected well before diagnosis was made. The results of these studies, however, have been confirmed only in part. A strong direct association is not yet widely accepted, and no specific carcinogenic compound or mechanism has been identified. Relevant aspects of GC and H. pylori epidemiology actually do not fit perfectly in a causal hypothesis (i.e., the geographical and gender distribution, the paradoxical association with duodenal ulcer) though, on the other hand, several other factors certainly play a role in the complex multifactorial process leading, over several decades, to GC. Studies focused on H. pylori eradication and its effects on lesions that predispose to GC (atrophic gastritis and metaplasia), however, represent a priority for research, in view of the potential preventive applications. This issue remains controversial, and it is possible that progression of these lesions might occur after eradication.

Widespread eradication of Helicobacter pylori: a debate

BACKGROUND

Helicobacter pylori eradication is recommended currently only in peptic ulcer patients. The accumulating evidence of a possible pathogenetic role of the germ in other pathological conditions, such as mucosa-associated lymphoid tissue lymphomas and (possibly) also functional dyspepsia and gastric cancer, creates increasing pressure in favor of an expansion of such indication. However, at present, cultural and practical considerations should discourage widespread screening and eradication programs.

METHODS

The basis for our study is a critical review of the literature.

RESULTS

The lack of a sound pathophysiological basis linking H. pylori infection to both dyspeptic symptom perception and gastric cancer risk sharply contrasts with the numerical and clinical relevance of these pathological conditions. Screening tests are not sufficiently cheap, easy, and reliable to be applicable on a large scale. Also, eradication therapies may provide suboptimal therapeutic effects and excessive side effects if applied by physicians who are not prepared culturally.

CONCLUSIONS

Improvement of pathophysiological, diagnostic, and therapeutic knowledge must be achieved before eradication programs can be proposed on a large scale.

Helicobacter pylori infection and gastric cancer. A nested case-control study in a rural area of Japan

We conducted a seroepidemiological nested case-control study to determine the association of gastric cancer with Helicobacter pylori infection and atrophic gastritis. A cohort of 2858 participants in an annual multiphasic health check-up were followed for eight years. Data for 45 gastric cancer cases and 225 sex-, age-, and address-matched control subjects were analyzed. Helicobacter pylori infection was determined by IgG antibodies, and atrophic gastritis was diagnosed by both serum pepsinogen I level (< or = 70 ng/ml) and the pepsinogen I/II ratio (< or = 3.0). Univariate analysis showed that Helicobacter pylori and atrophic gastritis were significantly associated with gastric cancer. In a multivariate analysis, atrophic gastritis was associated with significantly increased risk of cancer (odds ratio, 3.38; 95% confidence interval, 1.54-7.42); however, Helicobacter pylori was not associated with cancer (odds ratio, 1.84; 95% confidence interval, 0.59-5.72). These results suggest that Helicobacter pylori infection alone is not directly associated with gastric carcinogenesis but has an indirect relation to gastric cancer through the development of atrophic gastritis.

Clinical significance of PCR in Helicobacter pylori DNA detection in human gastric disorders

AIM: To investigate the clinical significance of the PCR assay in the diagnosis of gastric Helicobacter pylori (Hp) infection.

METHODS: Hp infection in gastric antral biopsied specimens was identified by using the polymerase chain reaction (PCR) to amplify the specific Hp urease gene fragments (PCR-Hp-DNA) in 154 patients with gastrointestinal disorders. Hp urease gene oligonucleotide primers specific for Hp (16s rRNA) were used. Urease test and enzyme-linked immunosorbent assay (ELISA) for anti Hp-IgG serum were also used as controls.

RESULTS: PCR-Hp-DNA was detected in 140 (91%) of the 154 patients, where patients 114 and 125 were found infected with Hp by urease test and ELISA Hp IgG, respectively. There was a marked difference in the Hp-positive rate between the PCR-Hp-DNA and the urease test or ELISA-Hp-IgG (P < 0.05). The Hp infection rate increased with age, although a minority of infected people developed signs and symptoms of gastric disorders. Hp infection is closely related to adenocarcinoma in both the gastric antrum as well as the down body of the stomach.

CONCLUSION: PCR is a sensitive and specific method for the detection of Hp in human gastric tissues. Detection of Hp DNA in vivo using this approach might improve the clinical diagnosis and epidemiological research related to H. pylori infection.

Significance of Helicobacter pylori infection as a risk factor in gastric cancer: serological and histological studies

We conducted a case-control study to examine the association of Helicobacter pylori infection as a risk factor in gastric cancer in the Japanese population. Serum IgG antibodies for Helicobacter pylori were determined in 55 consecutive patients with gastric cancer and in 75 age- and sex-matched mass survey subjects and 57 age- and sex-matched cancer-free patients with conditions considered at a high risk for development of gastric cancer (precancerous condition). We examined the histology in all subjects and particular focus was placed on the extent of Helicobacter pylori-associated gastritis. The seroprevalence of Helicobacter pylori in gastric cancer patients (82%) and those with a precancerous condition (89%) was significantly higher (P < 0.005) than that in the mass survey subjects (60%). Positive relative risk associations were found for patients with gastric cancer (odds ratio, 3, with 95% confidence intervals of 1.69-5.33) and those with a precancerous condition (odds ratio, 5.66, with 95% confidence intervals 2.66-12.03). Significant differences were found when comparisons were made among the case-control groups who were H. pylori-positive and had inflammatory cell infiltration (P = 0.0127). The characteristics of Helicobacter pylori in histologically examined gastric mucosa showed differences between Helicobacter pylori-infected and uninfected persons in all groups. However, for none of these groups was there a significant differences between background mucosa for Helicobacter pylori-infected persons with or without gastric cancer. Helicobacter pylori seroprevalence is strongly associated with an increased risk of gastric cancer and with a precancerous condition; histological investigation did not define additional factors that might be associated with increased cancer risk.

Helicobacter pylori acquisition in infancy after decline of maternal passive immunity

We evaluated the natural history of Helicobacter pylori infection and the host immune response in 80 infants, and determined seroprevalence of H. pylori infection in their Taiwanese mothers. Decline in passively transferred maternal anti-H. pylori IgG antibodies and subsequent H. pylori infection was assessed in infants over 14 mo. A sensitive and specific, 96-well microtiter ELISA for the detection of H. pylori IgG antibodies was used to evaluate maternal serum (single specimen) and their infants (birth, 1, 2, 3, 6, 12, and 14 mo). Sera were also evaluated by ELISA for the presence of anti-H. pylori IgM antibodies in the infants. Maternal H. pylori IgG seroprevalence was 62.5% [50/80; 95% confidence intervals (CI), 51-73%]. All infants born to the 50 seropositive mothers passively acquired maternal H. pylori IgG. Transplacentally transferred maternal anti-H. pylori IgG lasted until about the 3rd mo of life, and disappeared in nearly all the infants by 6 mo of age. Seven and one-half percent of infants (6/80; 95% CI, 3-16%) acquired H. pylori infection; two were born to H. pylori-negative mothers. Among the six IgG seropositive infants, an IgM response specific for H. pylori antigens was detected and appeared to precede the rise in IgG in five. We conclude that maternal passive transfer of IgG antibodies occurs in the infant and disappears by 6 mo of age. H. pylori infection is acquired in infancy in this population; IgM antibodies against H. pylori are detectable, seem short-lived, and appear to precede IgG antibody development.

Relation between histologic subtypes and location of gastric cancer and Helicobacter pylori

BACKGROUND

Epidemiologic studies have consistently shown an association between Helicobacter pylori infection and gastric cancer, and it is now widely accepted that this organism plays a role in the pathogenesis of this tumor. Nevertheless, there are discrepant results on its relationship with the histologic type and location of gastric cancer within the stomach. The aim of this study was to determine the seroprevalence of H. pylori in a group of gastric cancer patients and the association between H. pylori and specific histologic types of gastric cancer and tumor location within the stomach.

METHODS

Systemic IgG antibodies against H. pylori were assayed using an enzyme-linked immunosorbent assay technique in 48 patients (male to female ratio, 31:17; age range, 39-88 years; mean, 69 years) with histologically confirmed gastric cancer and 50 controls (male to female ratio, 33:17; age range, 40-77 years, mean, 64 years).

RESULTS

Thirty-one cases of gastric cancer were of the intestinal type, and 12 of the diffuse type; the remaining 5 were unclassified. Thirteen gastric cancers were located in the distal stomach (antrum/pylorus), 12 in the body, and 5 in the proximal stomach (cardia/fundus); the remaining 17 were unclassified because the tumor extended towards more than one location. The overall seroprevalence of H. pylori in patients with gastric cancer and controls was 85.4% and 66%, respectively (P < 0.05). The seroprevalence increased with increasing age in cancer patients, but the difference was not significant. H. pylori seroprevalence among patients with the intestinal type of gastric cancer was higher than in those with the diffuse type (P < 0.05). The prevalence of H. pylori infection was higher among patients with the cancer located distally than in those with the cancer located proximally (P < 0.05).

CONCLUSIONS

H. pylori seroprevalence was higher in gastric cancer patients than in controls. The prevalence of H. pylori infection in intestinal-type gastric cancer was clearly higher than in the diffuse type and in the control group. An association was found between H. pylori infection and tumors located distally (antrum/pylorus).

Helicobacter pylori infection and the risk of gastric cancer among the Korean population

Helicobacter pylori infection has been associated with chronic atrophic gastritis, a precursor of gastric cancer. We conducted a prospective, case-controlled study to investigate whether H. pylori infection increases the risk of gastric cancer in Korean people with a high risk of gastric cancer. We enrolled 160 gastric cancer patients who were confirmed by endoscopic biopsy during 1994 and 160 age-matched control subjects with non-ulcer dyspepsia were compared to document the relationship between H. pylori infection and gastric cancer. The presence of H. pylori infection was determined by the rapid urease test and/or histology by Wright-Giemsa staining. The overall presence of H. pylori infection was 60% in gastric cancer patients and 51.9% in age-matched control subjects (odds ratio 1.39; 95% confidence interval 0.894-2.17; P = 0.143). Carcinomas of cardia, body and antrum were not associated with H. pylori infection (odds ratio 1.43, 1.69 and 1.29, respectively; 95% confidence interval, 0.271-7.52, 0.787-3.62 and 0.689-2.43, respectively; P = 0.178, 0.177 and 0.642, respectively) nor was the intestinal or diffuse type of cancer (odds ratio 1.39 and 1.40, respectively; 95% confidence interval 0.791-2.45 and 0.681-2.87, respectively; P = 0.250 and 0.835, respectively). Gender was not a risk for gastric cancer. In contrast to previous studies, these results do not provide evidence of H. pylori infection for gastric carcinogenesis in Korea.

Gastritis classified in accordance with the Sydney system in patients with primary Sjögren's syndrome

BACKGROUND

According to some earlier reports, chronic atrophic gastritis is a common finding in Sjögren's syndrome. However, the findings are controversial. The aim of this study was to investigate the occurrence of gastritis classified in accordance with the Sydney System in patients with primary Sjögren's syndrome.

METHODS

Thirty-two consecutive patients (27 women, 5 men) with primary Sjögren's syndrome, and 64 age- and sex-matched control subjects with dyspepsia underwent gastroscopic examination. Mucosal biopsy specimens were taken from the gastric antrum and corpus.

RESULTS

Eight (25%) patients with Sjögren's syndrome and three (4.1%) control subjects had atrophic antral gastritis (P = 0.01). Atrophic corpus gastritis was more frequently found in control subjects, but the difference was not statistically significant. None of the subjects had severe (grade 3) atrophy. Gastric inflammation, in either the corpus or antrum, was found in 85% of patients with Sjögren's syndrome and in 61% of control subjects (P = 0.02). Helicobacter pylori was present in 31% of Sjögren's syndrome patients and in 39% of controls (NS).

CONCLUSIONS

In patients with primary Sjögren's syndrome mild atrophic changes in the antrum were common, but severe mucosal atrophy was rare. Compared with control subjects, gastric inflammation was seen more often in patients with Sjögren's syndrome.

Capsaicin as an inhibitor of the growth of the gastric pathogen Helicobacter pylori

Capsaicin, the active ingredient in chili, has been implicated as both a cytoprotective and a detrimental agent to the gastric mucosa. The effect of capsaicin on Helicobacter pylori has not been investigated previously. Therefore, we performed in vitro time- and concentration-dependent studies to examine the growth of H. pylori in the presence of capsaicin. Capsaicin specifically inhibited growth of H. pylori dose-dependently at concentrations greater than 10 micrograms ml-1 (P < 0.05) but did not inhibit the growth of a human fecal commensal Escherichia coli strain. Bactericidal activity was observed within 4 h. Capsaicin continued to exhibit bactericidal activity when incubated at pH values as low as 5.4. Ingestion of chili, therefore, could have a protective effect against H. pylori-associated gastroduodenal disease. This effect deserves further study in animal models.

The diagnostic value of enzyme immunoassay and immunoblot in monitoring eradication of Helicobacter pylori

55 patients with severe ulcer disease and H. pylori infection, successfully treated with antimicrobials, were followed-up with repeated blood samples for up to 32 months. Sera were analysed by enzyme immunoassay (EIA) for IgG and IgA antibodies and by IgG immunoblot. The EIA for IgG antibodies showed a high sensitivity (100%), while IgA antibodies above the cut-off level were found in 55% of the patients. At a median of 77 days after onset of treatment, approximately 50% of the patients showed a significant decrease (> or = 50%) of IgG or had titres below the cut-off level. All patients but 1 had a significant decrease of IgG after 6-12 months. The decrease was slower for IgA. The H. pylori-specific 116 kDa and 19.5 kDa bands were found in all pre-treatment samples, but the decrease in median intensity of the bands was slower than for the IgG EIA. In the 32-months post-treatment samples, both bonds had an intensity still above 50% of the pre-treatment value. The study showed that the IgG EIA is a useful method for monitoring eradication of H. pylori. Immunoblot can detect previous H. pylori infection in EIA negative Individuals.

Câncer de estômago: fatores de risco

Há cinqüenta anos o câncer de estômago vem perdendo a importância em termos de morbi-mortalidade em países considerados de primeiro mundo. Isso não ocorre no Brasil. Os principais fatores de risco evidenciados a partir de estudos epidemiológicos em várias populações do mundo e associados a essa neoplasia são alguns padrões de dieta. Com a descoberta do papel carcinogênico das nitrosaminas e do potencial anti-oxidante da vitamina C, algumas das associações entre câncer gástrico e padrões de dieta passaram a ser parcialmente entendidas. Com a descrição da Helicobacter pylori em 1983 e as evidências da relação dessa bactéria com certos processos patológicos do estômago, alguns precursores do câncer gástrico, novos elementos foram agregados ao processo fisiopatológico dessa entidade. O conhecimento hoje adquirido sobre a fisiopatologia do câncer gástrico, mesmo que parcial, fornece perspectivas estimulantes para prevenção e diagnóstico precoce.

Eradication of Helicobacter pylori and regression of B-cell lymphoma

There is an increasing body of evidence implicating a causal association between Helicobacter pylori and the development of mucosa-associated lymphoid tissue (MALT) associated B-cell gastric lymphoma. Investigators have noted that almost all patients with H pylori-associated chronic gastritis develop lymphoid follicles. Some of these patients demonstrate infiltration of B cells and lymphoepithelial lesions typical of MALT lymphoma. When gastric tissue from patients with gastric B-cell lymphoma is analyzed for H pylori infection, the overwhelming majority of patients demonstrate this condition. Epidemiologic nested case-control studies have shown that patients with gastric non-Hodgkin's lymphoma are substantially more likely that matched controls to have H pylori infection. This situation may be analogous to the linkage between chronic Epstein-Barr virus and lymphoma. The mechanisms inducing the development of lymphoma are not clear, but it has been suggested that chronic infection with H pylori results in the stimulation of H pylori-responsive T cells which in turn activate B cells with the subsequent development of a mutation to a monoclonal B-cell population. Recent evidence indicates that cure of H pylori infection produces regression of MALT lymphoma within 3 to 12 months in approximately 75% of antibiotic-treated patients. Individual responsiveness remains unpredictable, however, and careful and prolonged endoscopic and histologic follow-up is needed. Large, well-controlled studies are necessary, however, to determine the duration of 'cure' and the appropriate setting for treatment.

An apparent lack of association between Helicobacter pylori infection and risk of gastric cancer in China

Several prospective studies have shown a significant association between Helicobacter pylori seropositivity and the risk of gastric cancer. Only a small proportion of H. pylori-infected individuals will, however, develop gastric cancer, and it is unclear what effects other factors, such as diet, might have on the risk of cancer. Eighty-seven subjects with gastric cancer were identified during the first 6 years of follow-up (mean 2.4 years) of a cohort of middle-aged men from Shanghai, China. They were matched with 261 cancer-free controls, and serum samples from all subjects, obtained at recruitment, were assayed for anti-H. pylori IgG antibodies. Questionnaire data provided information on a wide range of socio-demographic life-style and dietary variables. H. pylori seropositivity rates in the cases and controls were 54% and 56%, respectively. Neither the overall risk of developing gastric cancer nor the risk of developing non-cardia gastric cancer was significantly associated with prior M. pylori seropositivity. Adjustment for any of the other medical, dietary or life-style variables studied had little effect on the risk of developing non-cardia gastric cancer; simultaneous adjustment for all of these factors yielded an odds ratio of 1.17. The results do not support the hypothesis that H. pylori plays a role in the process of gastric carcinogenesis in China. It is possible that this is an artefact resulting from the relatively short follow-up period to date.

Helicobacter pylori infection enhances mucosal interleukin-1 beta, interleukin-6, and the soluble receptor of interleukin-2

It is thought that Helicobacter pylori colonization of the gastric mucosa might stimulate the production of several cytokines, which might trigger and maintain the gastric inflammation associated with Helicobacter pylori infection. In the present study we evaluated interleukin-1 beta. interleukin-6, and the soluble receptor of interleukin-2 both in mucosal homogenates and in the sera of Helicobacter pylori-infected (39 cases) and uninfected (40 cases) patients to investigate whether there was any relationship between variations in cytokines and (1) the severity of Helicobacter pylori-associated gastritis or (2) CagA-positive Helicobacter pylori strains. Mucosal, but not serum levels of interleukins-1 and -6 and interleukin-2 receptor were significantly higher in infected than uninfected patients. Serum levels of Helicobacter pylori antibodies were significantly higher in infected than uninfected patients. These levels correlated with mucosal interleukin-1 beta. The degree of antral or body inflammatory grade was higher in infected than in uninfected patients; cytokines levels were higher in patients with high-grade gastritis, most of whom were Helicobacter pylori positive. Patients infected with CagA-positive strains also had higher levels of interleukin-1 beta, but not of interleukin-2 receptor or interleukin-6. In conclusion. Helicobacter pylori infection results in a local increase in interleukins-1 beta and -6 and interleukin-2 receptor associated with high-grade mucosal inflammation. Interleukin-1 beta seems to favor anti-Helicobacter pylori antibody production, and mucosal levels are enhanced mainly in patients infected with cytotoxic Helicobacter pylori strains.

Gastric juice polymerase chain reaction: an alternative to histology in the diagnosis of Helicobacter pylori infection

BACKGROUND

Infection from Helicobacter pylori plays a role in several gastroduodenal diseases. The recent availability of molecular techniques, particularly the polymerase chain reaction (PCR), allows us to detect small amounts of this bacterium. The aims of this study were to compare PCR and histological findings and to ascertain the clinical usefulness of H. pylori PCR identification in different biological samples.

MATERIALS AND METHODS

We studied 94 consecutive patients. Saliva, gastric juice, and four antral and four body biopsies were obtained from each patient. H. pylori was evaluated histologically in two antral and two body biopsies (Giemsa or Warthin-Starry stain). After extraction, DNA was submitted for PCR amplification using the two primers HPU1 and HPU2, which amplified a 411-bp product from the urease gene A.

RESULTS

Forty-nine patients were H. pylori-positive at histological workup. The sensitivity of PCR was 92% for gastric juice, 73% for antral biopsies, 61% for body biopsies, and 13% for saliva. Of the 45 H. pylori-negative patients at histological assessment, 7 (16%) had positive findings on PCR, mainly when gastric juice was examined.

CONCLUSIONS

These results indicate that PCR is as sensitive as histological assessment. We suggest that PCR H. pylori detection in gastric juice is a sensitive method for diagnosing this infection.

Helicobacter pylori infection in young patients with gastric carcinoma

BACKGROUND

Helicobacter pylori infection has been linked with chronic atrophic gastritis and gastric cancer. This case-control study was performed to investigate a possible relationship between H. pylori infection and gastric cancer in young age groups.

METHODS

Gastrectomy and/or biopsy samples were collected from 50 consecutive patients 45 years old or younger treated between 1980 and 1994 for noncardiac gastric cancer. The control group consisted of age- and sex-matched dyspeptic patients. The presence of H. pylori infection was assessed by modified Giemsa staining and immunostaining, using antibody against H. pylori.

RESULTS

H. pylori was found in 36 (72%; 95% confidence interval 60-84%) cancer patients and in 22 (43%; 30-58%) control patients (p = 0.0023, chi-square test). The odds ratio was 3.27 (1.42-7.52). Nonatrophic (superficial) gastritis was present in 30 (60%) cancer patients and in 19 (38%) (p = 0.028, chi-square test) control cases.

CONCLUSIONS

The results of the present study support the hypothesis that H. pylori is a risk factor for gastric cancer also in young age groups and in patients with a diffuse type of gastric cancer.

Long-term follow-up of gastric histology after Helicobacter pylori eradication

Helicobacter pylori causes chronic active gastritis and is thought to be associated with the development of gastric atrophy, intestinal metaplasia and carcinoma. As the effect of H. pylori eradication on this process is poorly understood, we sought to determine the long-term effects of H. pylori eradication on gastric histology. Fifty-four patients with duodenal ulceration associated with H. pylori infection received H. pylori eradication therapy in 1985/86 and either remained infected (n = 22) or had the infection eradicated (n = 32); patients were followed up by endoscopy with gastric antral biopsy for 7.1 years (mean). Histopathological analysis of gastric antral mucosa from patients rendered H. pylori-negative revealed a marked decrease in both inflammatory cells within the lamina propria and intraepithelial neutrophils and an increase in epithelial mucinogenesis. Gland atrophy remained unchanged in both H. pylori-positive and -negative patients. When examined for the presence and severity of intestinal metaplasia, there was neither a difference between the two patient groups nor a change with time. These data demonstrate that significant long-term improvements in gastric histology accompany H. pylori eradication when compared with histology in patients with persistent infection. Whether this confers a protective effect by reducing the risk of gastric carcinoma remains unknown.

Chronic proliferative hepatitis in A/JCr mice associated with persistent Helicobacter hepaticus infection: a model of helicobacter-induced carcinogenesis

Helicobacter hepaticus causes hepatitis in selected strains of mice and in A/JCr mice is linked to liver cancer. To analyze whether H. hepaticus persists in specified ecological niches, to determine whether biomarkers of infection exist, and to analyze the influence of H. hepaticus on hepatocyte proliferation, a longitudinal study of H. hepaticus-infected A/JCr mice was undertaken. A/JCr mice were serially euthanatized from 3 through 18 months and surveyed by enzyme-linked immunosorbent assay; bacterial culture of liver, colon, and cecum; histology; electron microscopy; hepatocyte proliferation indices determined by using 5-bromo-2'-deoxyuridine; and measurement of the liver enzyme alanine aminotransferase. In infected animals throughout the 18-month study, H. hepaticus was consistently isolated from the lower bowel but only sporadically from the liver. By electron microscopy, H. hepaticus was noted infrequently and only in bile canaliculi. Infected mice, particularly males, showed chronic inflammation; oval cell, Kupffer cell, and Ito cell hyperplasia; hepatocytomegaly; and bile duct proliferation. The inflammatory and necrotizing lesion was progressive and involved the hepatic parenchyma, portal triads, and intralobular venules. Hepatic adenomas were noted only in male mice, whereas 5-bromo-2'-deoxyuridine proliferation indices were markedly increased in both sexes, but especially in males, compared to control A/J mice. Infected mice also developed sustained anti-H. hepaticus serum immunoglobulin G antibody responses and elevated alanine aminotransferase levels. H. hepaticus, which persists in the lower bowels and livers of A/JCr mice, is associated with a chronic proliferative hepatitis, and hepatomas in selected male mice indicate that this novel bacterium may cause an increased risk of hepatic cancer induction in susceptible strains of mice. This murine model should prove useful in dissecting the molecular events operable in the development of neoplasms induced by bacteria belonging to this expanding genera of pathogenic Helicobacter species.

Chronic proliferative hepatitis in A/JCr mice associated with persistent Helicobacter hepaticus infection: a model of helicobacter-induced carcinogenesis

Helicobacter hepaticus causes hepatitis in selected strains of mice and in A/JCr mice is linked to liver cancer. To analyze whether H. hepaticus persists in specified ecological niches, to determine whether biomarkers of infection exist, and to analyze the influence of H. hepaticus on hepatocyte proliferation, a longitudinal study of H. hepaticus-infected A/JCr mice was undertaken. A/JCr mice were serially euthanatized from 3 through 18 months and surveyed by enzyme-linked immunosorbent assay; bacterial culture of liver, colon, and cecum; histology; electron microscopy; hepatocyte proliferation indices determined by using 5-bromo-2'-deoxyuridine; and measurement of the liver enzyme alanine aminotransferase. In infected animals throughout the 18-month study, H. hepaticus was consistently isolated from the lower bowel but only sporadically from the liver. By electron microscopy, H. hepaticus was noted infrequently and only in bile canaliculi. Infected mice, particularly males, showed chronic inflammation; oval cell, Kupffer cell, and Ito cell hyperplasia; hepatocytomegaly; and bile duct proliferation. The inflammatory and necrotizing lesion was progressive and involved the hepatic parenchyma, portal triads, and intralobular venules. Hepatic adenomas were noted only in male mice, whereas 5-bromo-2'-deoxyuridine proliferation indices were markedly increased in both sexes, but especially in males, compared to control A/J mice. Infected mice also developed sustained anti-H. hepaticus serum immunoglobulin G antibody responses and elevated alanine aminotransferase levels. H. hepaticus, which persists in the lower bowels and livers of A/JCr mice, is associated with a chronic proliferative hepatitis, and hepatomas in selected male mice indicate that this novel bacterium may cause an increased risk of hepatic cancer induction in susceptible strains of mice. This murine model should prove useful in dissecting the molecular events operable in the development of neoplasms induced by bacteria belonging to this expanding genera of pathogenic Helicobacter species.

Induction of nitric oxide synthesis in murine macrophages by Helicobacter pylori

Intact Helicobacter pylori cells, as well as cellular components, stimulated nitric oxide (NO) synthesis in an in vitro murine macrophage system by the L-arginine-nitric oxide pathway. Macrophage-mediated NO formation was dependent on the presence of H. pylori and exhibited a dose-dependent increase at H. pylori concentrations between 10(6) and 5 and 10(7) cells/ml. H. pylori mediated NO synthesis also required L-arginine and was inhibited by NG-monomethyl-L-arginine (NMMA), a selective inhibitor of nitric oxide synthase. NO synthesis was induced by whole H. pylori cells. H. pylori media filtrate, extracted membrane proteins, and H. pylori lipopolysaccharide (LPS). Maximal NO synthesis was induced by viable H. pylori cells with media filtrate and membrane protein extracts inducing significant NO responses. NO stimulation by media filtrate and membrane protein extracts support secreted H. pylori products as potential activators of inflammatory cell NO synthesis in vivo. NO synthesis in response to H. pylori suggests that chronic H. pylori infection may increase endogenous formation of NO. Elevated NO exposure may represent an etiologic factor explaining the epidemiologic association between long-term H. pylori infection and gastric cancer.

Spontaneous antibody-secreting cells in the stomach of gastric cancer patients

The gastric mucosa has been regarded as an active site of humoral immunity since the discovery of Helicobacter pylori. The present study was conducted to determine the in vivo activity of gastric B cells in 53 gastric cancer patients. B-cell activity was measured by protein-A plaque assay, in which IgA-, IgM-, and IgG-plaque-forming cells (PFC) were counted. The number of PFC was associated with the stage of cancer, but the response of lymphocytes in a non-tumorous area (NML) and tumor-infiltrating lymphocytes (TIL) differed. PFC in both sites were decreased compared to n0 cancer in n1 lymph node metastasis-positive cancer, while only NML showed raised PFC in n2 + (P < 0.05, vs TIL). Cancer cells penetrating the submucosa caused the PFC of TIL (but not of NML) to decrease. Invasion of the intratumor capillary (V) or lymphatic (Ly) vessels also caused PFC to change, showing differences of Ig class; there was a decrease of PFC in V2 (IgG- and IgM-PFC) and in Ly2 (all Ig-PFC). IgA-PFC in Ly1 differed in TIL (decrease of PFC) and NML (increase). PFC also differed in TIL and NML in cancer cells, as follows: TIL < NML in tubular and poorly differentiated adenocarcinoma and TIL > NML in papillary and signet ring cell adenocarcinoma. Changes in lymph node (LNL) and blood lymphocytes were similar to those in gastric PFC whose IgA value was 10 times as much as that of LNL. The 5-year survival rate was significantly better in patients with lower rather than higher PFC such as 89% vs 68%. Gastric B cells thus appear to be active and to reflect gastric mucosal immunity.

Antral nodularity, gastric lymphoid hyperplasia, and Helicobacter pylori in adults

Our objective is to evaluate endoscopically-diagnosed antral nodularity in adults and its relationship to lymphoid hyperplasia (LH) and Helicobacter pylori (HP). Antral biopsy specimens were studied for inflammation, presence of HP, and lymphoid follicles. Patients with marked functional dyspepsia or recurrent duodenal ulcers were given triple therapy (bismuth subcitrate, tetracycline, and metronidazole in the recommended doses for 2 weeks) to eradicate HP. Follow-up endoscopy and biopsies, at least 4 weeks after finishing treatment, were performed to assess eradication of HP and its effect on nodularity and LH. In all 25 patients (age range, 20-42 years) with antral nodularity, biopsy specimens were positive for HP. Twenty (80%) of subjects had lymphoid follicles; 13 of these 20 were given triple therapy. Eradication of HP was achieved in five cases (38%). Patients in whom HP was successfully eradicated showed improvement of their symptoms; antral nodularity subsided and there was marked regression of the lymphoid follicles. Antral nodularity with LH, reported to be unique to children, is not uncommon in adults and is induced by HP, eradication of which leads to regression of nodularity and LH in most cases. Low eradication rates achieved with metronidazole-based triply therapy is due, possibly, to primary resistance to metronidazole. Long-term follow-up of such patients is required to assess the evolution of these findings.

Helicobacter pylori infection and its role in human disease--an overview

Helicobacter pylori (H. pylori) is probably the commonest chronic bacterial infection in humans. The bacterium colonizes the gastric epithelium and induces inflammation of the underlying mucosa. The recognition that this infection is the most important acquired factor in the pathogenesis of duodenal and gastric ulcers has transformed the management of these common disorders. Most patients with ulcers can be cured by a 1-week course of anti-H. pylori therapy, thereby removing the need for long-term acid inhibitory therapy. Eradication of the infection involves taking complex combinations of drugs and simpler eradication regimens are required. Recent epidemiological data indicate an association between H. pylori infection and the subsequent development of gastric carcinoma. If this association is established as causal, then widespread eradication of the infection may be indicated. Global eradication of H. pylori will probably rely on prophylactic or therapeutic vaccination and this approach is being actively investigated.

Serum pepsinogen C: a useful marker of Helicobacter pylori eradication?

Medical treatment for Helicobacter pylori (Hp) infection is now recommended in several types of gastroduodenal disease, and its success is usually monitored by hystology. The end-points of our work were to identify the most suitable serum index of Hp eradication among pepsinogen A (PGA), pepsinogen C (PGC), PGA/PGC ratio, gastrin, and IgG anti-Hp (IGG). We studied a total of 289 Hp positive (Giemsa staining) patients, who were treated with 40 mg/day omeprazole (140 cases) or with 480 mg/day bismuth subsalicylate (149 cases) for 4 weeks. All the patients also received 1 g/day metronidazole + 2 g/day amoxycillin for the first 2 weeks of treatment. Two months after the end of therapy, the patient underwent a second endoscopy and Hp histological assessment: the infection was eradicated in 192 and still present in the remaining 97 subjects. Gastrin, PGA, PGC, and IGG were measured before and after therapy. All indices significantly decreased after therapy in eradicated patients, while PGA and gastrin significantly decreased after therapy in both eradicated and noneradicated patients, although in the latter group the variations were less pronounced. We calculated the per cent decrease of the studied indices. PGC, with a decrease of more than 25%, was found to be the most accurate biochemical index. Variation in PGC levels before and after treatment were correlated with corresponding variations in Hp bacterial load. In conclusion, between the different biochemical parameters evaluated, PGC showed the highest clinical efficiency.

Helicobacter pylori and gastric carcinogenesis

BACKGROUND

Helicobacter pylori causes chronic persistent gastritis in virtually all infected subjects, leading to development of atrophic gastritis, intestinal metaplasia and eventually dysplasia and gastric cancer in a number of infected subjects. Based on the available evidence, an IARC monograph committee classified H. pylori as a class I carcinogen to humans. Prospective studies suggest that infection increases the risk for atrophic gastritis and gastric cancer at least 8-fold. In the presence of infection, the risk for atrophy and cancer seems higher if a subject becomes infected in early childhood, if infection occurs with a cagA positive strain, and if acid output is decreased.

CONCLUSION

H.pylori is a gastric carcinogen. The clinical implications and possible strategies for cancer prevention have to be delineated in the near future.

Simultaneous gastric adenocarcinoma and MALT-type lymphoma in Helicobacter pylori infection

A 79-year-old women with upper abdominal pain, vomiting and weight loss was found at endoscopy to have a large tumour mass in the gastric body. Histology of forceps biopsies revealed an adenocarcinoma of intestinal type. Gastrectomy was performed, but extensive lymph node metastasis precluded a curative surgical approach. Histopathological study of the specimen, however, revealed two distict malignancies, which arose in the setting of Helicobacter pylori-associated chronic gastritis with partial mucosal atrophy. One tumour was a gastric carcinoma, while the other was a primary B-cell lymphoma of the stomach (CD20-positive). The lymphoma comprised both a low-grade component (mucosa-associated lymphoid tissue- or MALT-type lymphoma), and a high-grade component (large cell lymphoma with CD30-positive giant cells). Infection with H. pylori was confirmed by the serological presence of IgG antibodies to H. pylori-antigens, including antibodies against the 128 kDa protein of the cytotoxin-associated gene (cagA gene) of H. pylori.

Lack of association of Helicobacter pylori seroprevalence and gastric cancer in a population with low gastric cancer incidence

BACKGROUND

Previous studies have suggested that infection with Helicobacter pylori is associated with an increased risk of gastric adenocarcinoma.

METHODS

We examined the sera of 111 Caucasian patients with histologically confirmed gastric cancer (36 with cancer of the cardia, 70 with cancer of the body or antrum, and 5 with stump carcinomas after Billroth-II procedures) and 111 age-matched controls with colorectal carcinomas for the presence of H. pylori IgG antibodies by enzyme-linked immunoassay.

RESULTS

The overall prevalence of H. pylori infection was 58.6% (65 of 111) in gastric cancer patients as compared with 50.5% (56 of 111) in matched control subjects (odds ratio, 1.39; 95% confidence interval, 0.82 to 2.36). Carcinomas of the cardia were not linked to H. pylori infection (odds ratio, 1.25; 95% confidence interval, 0.65 to 2.46), nor diffuse or intestinal-type carcinomas (odds ratios, 1.79 and 1.0; 95% confidence intervals, 0.69 to 4.67 and 0.34 to 2.91, respectively). Age, sex, and height of the IgG immune response did not affect risk.

CONCLUSIONS

In contrast to previous results, these data do not provide evidence that the contribution of H. pylori infection to the carcinogenesis of gastric cancer is of major significance in a population with low gastric cancer rates and with high socioeconomic status.

Helicobacter pylori as a risk factor for cancer

In 1985, gastric cancer was the second most common cause of cancer death in the world. The rapid decline in gastric cancer rates over the last few decades has been attributed to a decline in the prevalence of environmental risk factors for gastric cancer and/or an increase in the prevalence of protective factors. One such risk factor could be the bacterium Helicobacter pylori. Epidemiological studies have shown that areas with high gastric cancer rates often have a correspondingly high prevalence of H. pylori and prospective studies have shown that subjects with serological evidence of H. pylori infection were significantly more likely to go on to develop gastric cancer than those who did not. Helicobacter pylori itself does not appear to be either genotoxic or mutagenic. Infection is, however, associated with increased cell turnover, a chronic immune response accompanied by increased levels of reactive oxygen metabolites and a reduction in gastric levels of ascorbic acid, all conditions that could favour the development of cancer. Nonetheless, the majority of those who are infected with H. pylori do not go on to develop gastric cancer and other factors, such as the strain of the infecting organism or consumption of dietary antioxidants including vitamin C, could also affect the risk of cancer. Finally, it has been estimated that more than one third, and possibly as many as 90% of gastric cancers might be attributable to infection with H. pylori. Prevention and treatment of infection are, therefore, possible approaches to reducing gastric cancer rates. It is, however, unclear what, if any, effect eradication of the infection would have on an individual's risk of gastric cancer and, to date, anti-Helicobacter therapy has only been shown to be of potential benefit in the treatment of low grade gastric MALT lymphomas.

Prevalence of Helicobacter pylori infection in subtypes of gastric cancer

BACKGROUND & AIMS

Although Helicobacter pylori has already been declared a human carcinogen, the exact nature of the association with gastric cancer remains to be explored. The aim of this study was to determine if the association is confined to specific types of gastric cancer.

METHODS

The prevalence of H. pylori immunoglobulin G antibodies (HM-CAP immunoassay; Enteric Products Inc., Westbury, NY) was determined in prospectively collected sera from 279 patients with gastric cancer.

RESULTS

The overall prevalence of H. pylori seropositivity was 77%. The prevalence of H. pylori infection was significantly lower among patients with tumors of the gastric cardia compared with those with other gastric locations. Age-adjusted H. pylori seroprevalence among patients with the intestinal type of gastric cancer tended to be higher than among those with the diffuse type according to Laurén (P > 0.05). In both histological types, the seroprevalence decreased with increasing age. Multivariate logistic regression analysis showed that high age and proximal tumor location were independent predictors of absence of H. pylori.

CONCLUSIONS

The association with H. pylori infection is similar regardless of the histological features of the tumor, whereas it is stronger for noncardiac gastric cancer than for cardiac cancer. The apparent loss of H. pylori seropositivity among patients with gastric cancer is determined by age rather than tumor stage.

Serum anti-Helicobacter pylori antibody and gastric carcinoma among young adults. Research Group on Prevention of Gastric Carcinoma among Young Adults

BACKGROUND

Helicobacter pylori is recognized as one of the possible causes of gastric carcinoma. There have been few studies on the relationship between H. pylori and gastric carcinoma in patients younger than 40 years.

METHODS

Data and sera were collected from the cases (105 hospitalized patients younger than 40 years with gastric carcinoma from 9 hospitals in the Kanto-Shin-Etsu Area in Japan) and controls (102 hospitalized control subjects and 101 screening control subjects) whose sex and age (within 4 years) were matched. The serum anti-H. pylori immunoglobulin G antibody was measured, and the odds ratio (OR) for the association between seropositivity and gastric carcinoma was calculated.

RESULTS

The OR (95% confidence interval) was 13.3 (5.3-35.6). For women, the OR was 32.8, whereas for men it was 6.8. The OR for patients with early gastric carcinoma was 20.8, and for patients with advanced disease, it was 10.8. The OR for intestinal-type carcinoma was 18.0, and for diffuse-type carcinoma, it was 12.8. The OR for proximal carcinoma was 11.3, and for distal carcinoma it was 14.8.

CONCLUSION

The OR for these young subjects was considerably larger than that for the older subjects in previously published studies. Among those younger than 40 years of age, early stage carcinoma has a stronger association with H. pylori than advanced carcinoma, and intestinal- and diffuse-type carcinomas have an association with H. pylori.

Characterization of a Helicobacter pylori neutrophil-activating protein

Helicobacter pylori-associated gastritis is mainly an inflammatory cell response. In earlier work we showed that activation of human neutrophils by a cell-free water extract of H. pylori is characterized by increased expression of neutrophil CD11b/CD18 and increased adhesiveness to endothelial cells. The work reported here indicates that the neutrophil-activating factor is a 150,000-molecular-weight protein (150K protein). Neutrophil proadhesive activity copurified with this protein, which is a polymer of identical 15K subunits. Specific antibody, prepared against the purified 15K subunit, neutralized the proadhesive activity of the pure protein and of water extracts obtained from different strains of H. pylori. The gene (napA) for this protein (termed HP-NAP, for H. pylori neutrophil-activating protein) was detected, by PCR amplification, in all of the H. pylori isolates tested; however, there was considerable strain variation in the level of expression of HP-NAP activity in vitro. HP-NAP could play an important role in the gastric inflammatory response to H. pylori infection.