ABSTRACT
Purpose: Many virulence factors are involved in the pathomechanism of infection caused by Helicobacter pylori. Toxins such as vacuolating cytotoxin, encoded by the vacA gene and the immunogenic protein cagA, encoded by the cagA gene (cytotoxin-associated gene) are major factors conferring the property of virulence. The current study is aimed at isolation of H. pylori and separation of its toxin from antral biopsies of patients. Materials and Methods: The following cell lines were used to demonstrate the cytopathic effect (CPE) of the separated toxin: African green monkey kidney (Vero), baby hamster kidney, human lung carcinoma (LLC-MK2), and human epithelial. Results: H. pylori was isolated from 27 out of 45 patients (60%) selected for the study. CPE of H. pylori toxin was highly signifi cant on Vero cells than other cell lines used as it reached a high dilution titer of toxin (1/16) in 13 isolated strains (48.15%). No signifi cant difference in CPE of toxin in different dilutions was detected among other cell lines used in different groups. H. pylori toxin could be detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis as a distinct band with a molecular weight ranging between 66 and 97 kDa and closely related to 87 kDa. Conclusion: H. pylori vacuolating cytotoxin plays a vital role in the pathogenesis of gastroduodenal diseases (gastritis, gastric ulcer, duodenal ulcer, and gastric cancer). The Vero cell lines were found to be the most suitable form of tissue culture when compared with other cell lines used in our study for demonstrating the activity of H. pylori toxin.
ABSTRACT
To observe the effect of Helicobacter pylori(H.priori) on cell gap junction ultrastructure of gastric epithelial cells,and to explore carcinogenic mechanism of H.priori from the changes of cell gap junction,BGC-823 cells were co-cultured with different H.prlori strains for 24 h and 48 h.The cell gap junction ultrastructure was observed under transmission electron microscope with sample preparation of fixation and embedding in situ.In 70 patients with gastric eancer(GC),H.priori was detected by rapid urease test,basic fuchsin stain and 14C-urea breath test.The CagA gene of H.prlori was determined by PCR and the cell gap junction ultrastructure was observed under transmission electron microscope.More cell gap junctions and junction complexes of BGC-823 cells were found in control group without H.priori.Groups with H.priori had less number of cell gap junctions,less number of junctions/unit perimeter,shorter length of junctions/unit perimeter,and bigger width of the intercellular space,comparing to control groups without H.priori(P＜ 0.001 or P＜ 0.005).The number of cell junctions and the number of junctions/unit perimeter in the groups co-cultured with NCTC J99,GC 01 and NCTC 11639(CagA+) were less than that in the groups co-cultured with NCTC 12908(CagA-)(P ＜0.001 or P＜0.05),and the length of junctions/unit perimeter in the groups co-cultured with NCTC J99 and GC 01 was shorter than that in the groups co-cultured with NCTC 12908 (P＜ 0.001).In patients with GC,the number of cell junctions,the number of junctions/unit perimeter and the length of junctions/unit perimeter in group H.priori infection were all less than those in group without H.prior/infection(P ＜0.001),and that in CagA+ H.prlori group were less than that in CagA- H.prlori group,but its smallest width of the intercellular space was longer than that in CagA- H.prlori group.The above results showed that the changes of cell gap junction of gastric epithelial cells were associated with H.prlori infection especially CagA+ H.prlori infection.
ABSTRACT
Objective To investigate the correlation between H.pylori strain possessing cagA gene and the formation of gastric lymphoid follicles(GLF),and the effect of H.pylori infection on the occurrence of GLF.Methods Antral biopsy specimens from 655 patients (chronic gastritis:n=479,peptic ulcer:n=176)were used for detection of H.pylori infection and histological analysis. CagA gene was examined in 70 clinical isolates by means of PCR－ amplification. Results The incidence of lymphoid follicles in gastric mucosa is significantly higher(60.14％ ) in patients with H.pylori infection than those without infection(17.06％ ).GLF is easier to be detected in patients with active gastritis than in those with inactive gastritis. There is no significant difference in the presence of GLF among H.pylori associated gastroduodenal diseases,such as chronic gastritis ,gastric ulcer. Moreover, there is also no significant relationship between H.pylori strains possessing cagA gene and GLF. Conclusion The presence of GLF might directly related with H.pylori infection, and can be observed as a constant morpholgical marker of H.pylori related gastroduodenal disease ;The formation of gastric lymphoid follicles is not related to the cytotoxin of cag A gene of H.pylori.
ABSTRACT
BACKGROUND AND AIMS: To further understand the relationship between the cagA gene and gastric cancer, the positive rates of the cagA gene in cancer and non-cancer tissues were investigated separately in patients with gastric cancer. METHODS: The cagA gene was detected by PCR and the ureC gene was analyzed as a positive control for the presence of Helicobacter pylori. Each of two endoscopic biopsies were obtained from cancer and non-cancer tissues of 41 patients with gastric cancer. RESULTS: 1) The positive rate of the cagA gene in cancer tissues was 29.3% (12/41), which was significantly lower than that in non-cancer tissues (63.4%). 2) Twelve (29.3%) out of 41 were positive for the cagA gene in both cancer and non-cancer tissues, 14 were positive in only non-cancer tissues, none were positive in only cancer tissues, and 15 (36.6%) were negative in both sites. 3) The ureC gene was negative in cancer tissue in 12 (85.7%) among 14 cases who were cagA gene negative in the cancer tissue but positive in the non-cancer tissue. 4) There was no difference in the positive rate of the cagA gene according to age, stage, site, and pathologic cell type. CONCLUSIONS: These findings indicate that the positive rate of the cagA gene in cancer tissue was lower than that in non-cancer tissues and this might be related to a low infection rate of H. pylori in cancer tissue rather than the presence of cagA negative H. pylori in cancer tissues.