Campylobacter pyloridis in patients with gastric carcinoma

Epidemiological review of gastric cancer in India

Stomach cancer is the one of the leading cause of cancer in southern region of India. Its incidence is decreasing worldwide yet on global scale stomach cancer remains one of the most common causes of cancer death. Etiology of gastric cancer includes Helicobacter pylori infection, diet and lifestyle, tobacco, alcohol and genetic susceptibility. In this review, we tried to find the contribution of Indian scientist in understanding the descriptive and observational epidemiology of stomach cancer. PubMed was used as a search platform using key words such as "stomach cancer, treatment, clinical characteristics, stomach cancer outcome, epidemiology, etiological factor and their corresponding Mesh terms were used in combination with Boolean operators OR, AND". Most of the reported studies on gastric cancer from India are case report or case series and few are case-control studies. Indian studies on this topic are limited and have observed H. pylori infection, salted tea, pickled food, rice intake, spicy food, soda (additive of food), tobacco and alcohol as risk factors for gastric cancer. More research is required to understand the etiology, develop suitable screening test, to demarcate high-risk population and to develop and evaluate the effect of primary prevention programs.

Synchronous adenocarcinoma and low grade B-cell lymphoma of mucosa associated lymphoid tissue (MALT) of the stomach

We describe nine cases of gastric adenocarcinoma (six intestinal and three diffuse type) occurring in the stomach synchronously with primary low grade B-cell lymphoma of mucosa associated lymphoid tissue. In four cases the two neoplasms were admixed to form collision tumours. Where collision was present between lymphoma and adenocarcinoma of intestinal type no lymphoepithelial lesions were seen involving neoplastic glands. Helicobacter pylori-like organisms were seen in seven cases (78%) which is consistent with an aetiological role for this organism in both tumours in the stomach.

Helicobacter pylori infection in gastric cancer: A study of 84 cases from Asir Region

Gastric cancer can be divided into three histologic types: intestinal and diffuse adenocarcinoma, and malignant lymphoma. To determine whether Helicobacter pylori was associated with either cancer type, we reviewed histologic sections from stomachs of 84 patients with the diagnosis of gastric. Of 63 patients with histologic evidence of intestinal adenocarcinoma, 53 (84%) contained H. pylori n noncancerous tissue compared with six (66.7%) of nine patients with diffuse adenocarcinoma (odds ratio = 2.65; Z=1.048; P>0.05) and with eight (66.7%) of 12 patients with non-Hodgkin malignant lymphoma of the stomach (odds ratio = 2.65; Z=0.826; P>0.05). Our findings are compared with reported data from other countries and we are not aware of similar reports from the Kingdom of Saudi Arabia.

The association of Helicobacter pylori with gastric cancer and preneoplastic gastric lesions in Chiapas, Mexico

BACKGROUND

Helicobacter pylori recently was identified as a risk factor for gastric cancer. Its association with preneoplastic conditions of the stomach, however, is undocumented.

METHODS

Gastric biopsy specimens from 245 symptomatic patients were examined for neoplastic and preneoplastic lesions and for gastric H. pylori infection. The sera of 183 subjects were tested by enzyme-linked immunosorbent assay (ELISA) for anti-H. pylori immunoglobulin G.

RESULTS

Histologic H. pylori infection, usually accompanied by acute and chronic gastritis, was found in 85.7% of patients. There was a strong association between H. pylori in the tissue and atrophy (relative risk, 15.0; 95% confidence interval, 4.2-56.6), intestinal metaplasia (relative risk, 5.7; 95% confidence interval, 1.9-16.8), and dysplasia or cancer (relative risk, 4.0; 95% confidence interval, 1.1-14.8). The ELISA was 93.2% sensitive and 57.1% specific for histologic infection with a positive predictive value of 96.1%. The overall seroprevalence rate was 86.1%, with no significant difference in rates between patients with cancer precursors and those with normal stomachs.

CONCLUSIONS

In this high-risk population, precursor lesions for adenocarcinoma were associated universally with H. pylori infection.

16S rrn gene copy number in Helicobacter pylori and its application to molecular typing

The copy number of the genes encoding 16S ribosomal RNA was analysed for the genomes of geographically diverse strains of Helicobacter pylori, and restriction site variation within and around the genes was characterized. A DNA probe of 550 bp was amplified by the polymerase chain reaction from genomic DNA of the type strain NCTC 11637. This probe constituted a sequence internal to the 3' end of the 16S rrn gene. Homology profiles were compared for genomic Southern blots made with four restriction enzymes cutting within and outside the probe sequence. A copy number of two was established for all 12 strains analysed. This approach yielded significantly simpler data than does conventional 'ribotyping ' of H. pylori. It was equally discriminatory, however, and provided strain-specific 16S rrn gene 'signatures'. These represent both fundamental physical-genetic information and a novel approach to typing this gastric pathogen.

Molecular typing of Helicobacter pylori by chromosomal and plasmid DNA organization

Diverse strains of Helicobacter pylori were examined in order to initiate a molecular epidemiological typing scheme for this agent of human gastritis. Twelve differently-sized plasmids from 1.8 to 63 kbp were identified in those strains harbouring extrachromosomal DNA. Recombinant DNA probes were cloned randomly from the chromosome of the (plasmid-free) type strain (NCTC 11637), and used to probe genomic Southern blots for restriction site variation in and around homologous loci. Genus-specific probe DNAs were obtained which grouped strains on the bases of DNA base substitution or rearrangements. On the basis of the four probes examined, all strains exhibited intraspecific chromosomal divergence, indicating that H. pylori is highly diverse genetically, but nonetheless susceptible to chromosome and plasmid molecular typing.

Gastric carcinoma: failed adaptation to Helicobacter pylori

Helicobacter pylori is the major cause of chronic gastritis. Unlike bacterial infections in general, H. pylori acquisition causes a chronic, usually life-long infection. After acquisition, chronic inflammation (gastritis) appears and develops slowly into atrophic gastritis (with intestinal metaplasia) in a proportion of affected subjects. Inflammation and atrophy result from a failure of the immune system to eliminate the H. pylori infection. In infected stomach, several cascades of reactions are triggered which may result in impairments of structure and function of the gastric mucosa, some of which lesions also increase the risk of gastric carcinoma (CGA). A sequence of events from an early H. pylori infection into an atrophic gastritis has risen a theory that the H. pylori acquisition is a key issue in the development of GCA. Several aspects in the epidemiology and pathogenesis of GCA can be understood and explained by this infectious background. The H. pylori gastritis is unexpectedly common in patients with GCA of both intestinal or diffuse type, and the infection and gastritis precede the development of cancer. In Finland, 70-80% of the GCA cases seem to develop in connection with an H. pylori-positive gastritis or atrophy, 10-15% develop in a normal stomach (genetically determined GCA cases?), and 10-15% are associated with an H. pylori-negative corpus-limited (autoimmune) gastritis and atrophy. Case control studies suggest that the presence of H. pylori related inflammation raises the risk of GCA twofold, and the appearance of atrophic gastritis (and intestinal metaplasia) raises further this risk 2-3 times, as compared to the risk of GCA in subjects with a normal stomach.

Identification, characterization, and spatial localization of two flagellin species in Helicobacter pylori flagella

Flagellar filaments were isolated from Helicobacter pylori by shearing, and flagellar proteins were further purified by a variety of techniques, including CsCl density gradient ultracentrifugation, pH 2.0 acid disassociation-neutral pH reassociation, and differential ultracentrifugation followed by molecular sieving with a Sephacryl S-500 column or Mono Q anion-exchange column, and purified to homogeneity by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transfer to an Immobilon membrane. Two flagellin species of pI 5.2 and with apparent subunit molecular weights (Mrs) of 57,000 and 56,000 were obtained. N-terminal amino acid analysis showed that the two H. pylori flagellin species were related to each other and shared sequence similarity with the N-terminal amino acid sequence of Campylobacter coli, Bacillus, Salmonella, and Caulobacter flagellins. Analysis of the amino acid composition of the predominant 56,000-Mr flagellin species isolated from two strains showed that it was comparable to the flagellins of other species. The minor 57,000-Mr flagellin species contained a higher content of proline. Immunoelectron microscopic studies with polyclonal monospecific H. pylori antiflagellin antiserum and monoclonal antibody (MAb) 72c showed that the two different-Mr flagellin species were located in different regions of the assembled flagellar filament. The minor 57,000-Mr species was located proximal to the hook, and the major 56,000-Mr flagellin composed the remainder of the filament. Western immunoblot analysis with polyclonal rabbit antisera raised against H. pylori or Campylobacter jejuni flagellins and MAb 72c showed that the 56,000-Mr flagellin carried sequences antigenetically cross-reactive with the 57,000-Mr H. pylori flagellin and the flagellins of Campylobacter species. This antigenic cross-reactivity did not extend to the flagellins of other gram-negative bacteria. The 56,000-Mr flagellin also carried H. pylori-specific sequences recognized by two additional MAbs. The epitopes for these MAbs were not surface exposed on the assembled inner flagellar filament of H. pylori but were readily detected by immunodot blot assay of sodium dodecyl sulfate-lysed cells of H. pylori, suggesting that this serological test could be a useful addition to those currently employed in the rapid identification of this important pathogen.