| The mortality of gastric cancer is the highest among all kinds of tumors in China. About 500,000 people have been dead of gastric cancer for every year. Carcinogenic factors that have been confirmed include Helicobacter pylori ( Hp) infection, nitroso compound and other factors such as high salt foods, male and familial hereditary abnormality. Studies showed that gastric cancer had correlated with chronic atrophic gastritis, which important change from normal gastric mu-cosa is intestinal metaplasia, not only in high - risk gastric cancer region but also in low risk one. Intestinal metaplasia has been divided into three subtypes: I , II and III. Glandular epithelium of Subtype I , mostly secreting sialomucin, is made up of mature absorptive cells and goblet cells; Glandular epithelium of subtype II , which mostly secreting sialomucin and less neutral and/ or sulphomucin at the same time, has few or even no absorptive cells and different differetiation stages of columnar mucous cells; Structure of glandular ducts of subtype III, which secreting mostly sulphomucin and sialomucin and/ or neutral mucin at the same time, are found distortion. Cell atypical characteristic and cell depolarization degree of subtype III are much obvious than subtype II. Chronic atrophic gastritis can accompany bydifferent intestinal metaplasia subtypes. But it has not yet been reported that chronic atrophic gastritis accompanied by which kind of intestinal metaplasia subtype has the closest relation with gastric cancer.It is considered by Correa that intestinal gastric cancer went through chronic gastritis, intestinal metaplasia, dysplasia and gastric cancer. Researches show that long - term and chronic Hp infection had been an initial factor, which acted on initial stage, in the multi-factor and multistage development of gastric cancer. Composite factor was the final cause of gastric cancer. Hp which has been generally acknowledged as I type carcinogenic factor, has a definite relationship with gastric cancer. Studies showed that Hp could be detected out at the stage of gastric precancerous diseases. But it has been not reported yet whose biologic acts would be much closer to gastric cancer, chronic atrophic gastritis accompanied by or not by Hp infection.Telomere, consisted of 2 to 20kb short tandem repeat sequence (TTAGGG) n and some special structure composed of telomere binding protein, lies in human chromosomes end. Base pares of theses repeat sequence are different because of their species. Telomere plays an important role in the location, replication, protection of human chromosomes and controlling cell growing. Telomerase is a ribonucleo-protein ( RNP) composed of RNA and proteins. It consists of a template of telomere repeat sequence. It can synthesize telomere sequence by using template, its own RNA component. There is no expression of telomerase activity in normal somatic cells, except spermatogonium and some blood stem cells, while there is expression of telomerase activity in 85% cancer tissues. Cell immortality is the biggest difference between tumor cells and normal cells' biological action. Telomerase activation, which has close relationship with developing progress ofcancer, is one of the needs of cell immortality and cell canceration. Telomerase activity, a special marker of tumors that have proliferation characteristics, is now a new point of tumor researches.In my study, telomerase activity was detected in normal gastric mucosa, chronic atrophic gastritis accompanied by different kind of intestinal metaplasia and by or not by Hp infection and gastric cancer, in order to investigate the expression of telomerase activity in different kind of gastric diseases, affection on expression of telomerase activity in chronic atrophic gastritis by Hp infection and the change of telomerase activity before and after Hp eradication. Relationship between Hp infection and telomerase activity and expression of telomerase activity in chronic atrophic gastritis accompanied by different subtypes of intestinal metapla... |
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