| The stomach cancer with high fatality rate is one of common digestive tract tumors threatening human health. However, its mechanism for causing disease has not been clearly discovered. The Helicobacter pylori (Hp) infection has close relationship with the occurrence of the stomach cancer. In 1994, WHO cancer research center listed Hp as I kind of carcinogenic factor. Hp is recognized as a kind of microorganism possessing genetic polymorphism, and different genotypes may lead to difference in pathogenicity. Ningxia is a region with a high incidence of gastric cancer whose causes are unknown. Presently, it is not yet discovered whether the distribution of genotypes of Helicobacter pylori is related with occurrence of gastric cancer or not. The objectives of this dissertation are to determine Hp genotypes for chronic atrophic gastritis, peptic ulcer, chronic superficial gastritis, and stomach cancer occurred in Ningxia by directly extracting the gastric mucosa Hp DNA, to discuss the relationship between specific genotype and chronic gastrointestinal diseases, and to explore whether some specific Hp infection subtypes are related with local high incidence of gastric cancer.117 gastric biopsy specimens with infection of Hp in chronic superficial gastritis, duodenal ulcer, gastric ulcer, and chronic atrophic gastritis were collected from gastric cancer patients. Then two pieces of gastric mucosa tissue specimens from greater curvature of the stomach sinus and two pieces of gastric mucosa tissue specimens from lesser curvature of the stomach sinus were respectively collected from patients whose gastric biopsy specimen illustrated strong positive reaction in both rapid urease test and pathology HE staining. All cases were confirmed to have Hp positive reaction in HE staining. Hp genomic DNA was directly extracted from the gastric mucosa by OMEGA EZNATM Tissue DNA Kit, and Polymerase Chain Reaction (PCR) method was employed to detect subtypes. Finally, cagA subtypes and the relationship between genes of oipA and cagX and specific chronic gastrointestinal diseases were analyzed.The results showed as follows: (1) All Hp cagA genes in the infected patients were tested as the East Asian-type cagA gene, and its positive rate was 88.8%. Western-type cagA gene was not detected. The East Asian-type cagA positive rates were 70% in chronic superficial gastritis patients, 90% in duodenal ulcer patients, 89.5% in gastric ulcer patients, 93.5% in chronic atrophic gastritis patients, and 96.3% in gastric cancer patients, respectively. The East Asian-type cagA distribution in 5 kinds of infections showed a statistical significance (P <0.05). The East Asian-type cagA positive rate in the chronic superficial gastritis patients infected by Hp cagA gene was statistically significantly different from that in duodenal ulcer patients, gastric ulcer patients, chronic atrophic gastritis patients, and gastric cancer patients. However, the frequency distribution of cagA subtypes in duodenal ulcer patients, gastric ulcer patients, chronic atrophic gastritis patients, and gastric cancer patients did not have significant difference. (2) Hp oipA gene positive rate was 40.18%. The oipA gene positive rates were 0% in chronic superficial gastritis, 51.6% in chronic atrophic gastritis patients, 30% in duodenal ulcer patients, 31.58% in gastric ulcer patients, and 70.37% in gastric cancer patients, respectively. The frequency distribution of Hp oipA gene in superficial gastritis patients, gastric patients, chronic atrophic gastritis patients, gastric cancer patients was significantly different. (3) Hp cagX gene positive rate was 57.26%. The cagX gene positive rates were 70% in chronic superficial gastritis patients, 60% in duodenal ulcer patients, 52.63% in gastric ulcer patients, 48.39% in chronic atrophic gastritis patients, and 51.61% in gastric cancer patients. The frequency distribution of Hp cagX gene in chronic superficial gastritis patients, duodenal ulcer patients, gastric antrum patients, chronic atrophic gastritis patients, and gastric cancer patients was not significantly different.Based on these results, Helicobacter pylori with cagA-East Asian is the dominant genotype in gastric diseases patients in Ningxia, and it is related with occurrence of duodenal ulcer, chronic atrophic gastritis, and stomach cancer. Helicobacter pylori with cagA-East Asian might be the main cause of high incidence of gastric cancer in NIngxia. The oipA gene might be another toxic gene in Hp according to its high distribution rate in gastritis, atrophy gastritis, duodenal ulcer and the gastric ulcer. Patients infected by Hp oipA gene will be at higher risk in being attacked by peptic ulcer, chronic atrophic gastritis, and stomach cancer. The fact that Hp oipA gene positive rate in stomach cancer patients is much higher than that in other patients with benign pathology illustrates that this gene might be related with occurrence of stomach cancer. The frequency distribution of Hp cagX gene in chronic superficial gastritis patients, duodenal ulcer patients, gastric antrum patients, chronic atrophic gastritis patients, and gastric cancer patients was not significantly different, and further study on Hp cagX gene is needed. |
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