| ObjectHp persistently colonizes the mucosa of the human stomach, causes chronic gastritis, and is an important risk factor for gastroduodenal diseases, such as peptic ulcers and gastric carcinoma. There is evidence that these genetic differences may play a role in the clinical outcome of the infection, particularly Hp virulence associated genes such as cagA,vacA and iceA genes, et al.Approximately 50 - 60% of the Hp strains contain cagA gene. The presence of cagA is associated with duodenal ulceration, gastric mucosal atrophy, and gastric cancer. cagA can be considered as a marker for the cagPAI. The N - terminal signal ( s ) region of vacA gene occurs as either an si or s2 allele. The middle (m) region is present as an ml or m2 allele. The vacA s and m regions appear to have different clinical relevance. vacA si a strains are associated with greater antral mucosal neutrophil and lymphocyte infiltrates than type sib or s2 strains. vacA type ml strains are associated with greater gastric epithelial damage than type m2 strains. Recently, a new candidate gene designated iceA was suggested to have an association with peptic ulcer. The iceA gene has two main allelic variants, iceAl and iceA2. iceAl allele was associated with peptic ulcer.Van Doom et al found in northern and eastern Europe, 89% were subtype si a, whereas in Spain and Portugal 89% of strains were subtype sib. vac A m2b strain was associated with east Asia strains sic. iceA genotype also has significant geographic distribution. In Japan and Korea, the iceAl allele was predominant irrespective of the disease. In Shanghai and Guangdong of China, si ml is the main genotype. Until now the distribution of these three genes in north China is not clear.Zhuanghe in Liaoning province is a high - risk area of gastric cancer of north China. The mortality of stomach is 49.55 for male and 22.23 for female per one hundred thousand. There is not only a high prevalence of gastric cancer but also a high popularity of Hp infection in this area. But how about the virulence gene strain infection, whether there are some differences with the low - risk area, whether it has some relationships with gastric diseases are not clear. The aim of this study is to make the discrimination of Hp genotypes distribution in the high and low areas of gastric cancer, discuss its relationship with associated gastric diseases and give a clue to elucidating carcinogenesis mechanism and detecting the high - risk persons of gastric cancer; to make the discrimination of Hp genotypes distribution in north China with that of other countries, explore its geographic characteristic and give a clue to studying the relationship between Hp infection and associated gastric diseases.Materials and MethodsA total of 491 cases were involved in this study. 136 cases of them came from Shenyang area,355 cases came from Zhuanghe, anarea with high gastric cancer mortality, in the east of Liaoning Province. Hp strains were grown at 37℃ on brain heart infusion plates containing 7% sheep blood in a5%O2,10% CO2,85% N2, incubator with 95% relative humidity. Standard phenol - chloroform - isoamyl method was used to extract DNA from Hp strain. PCR was used to exam cagA, vacA and iceA genotypes of Hp DNA. Three biopsy specimens were obtained from antrum, corpus and bottom. After embedding in paraffin and staining with HE, histopathology diagnosis was assessed.X or Fisher' s exact test was used for analysis of data for different areas. A p value of <0.05 was accepted as statistically significant.ResultsUrease positive strain DNA was used to study. Hp vacA si gene positive rate in the high - risk area is higher than that of low - risk area ( p <0. 001). There are 22 cases Hp strains with vacA gene mosaic combination slmlb in the high - risk area, but only one of this genotype can be found in the low - risk area (p<0.01). If the presence of multiple H. pylori strains in the same individual was judged by iceAl and iceA2, there are higher incidences in both areas than that reported in other cou...
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