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Objective: To study COX-2 expression in H. pylori infected gastric mucosal epithelia and its significance in the carcinogenesis of the stomach., Methods: Rapid urease test and histological examination with basic magnenta staining were used to assess the status of H. pylori infection in the stomach. COX-2 was detected immunohistochemically., Results: COX-2 immunostaining was positive in 1 out of 12 cases with H. pylori-negative gastric mucosa and also in 1 out of 10 cases with H. pylori-positive gastric mucosa without macroscopic alterations, while COX-2 expression was found to be positive in 5 out of 9 cases with H. pylori related superficial gastritis with mucosal erosions. COX-2 expression was detected in 5 out of 10 cases with H. pylori-positive mild atrophic gastritis, 8 out of 10 cases with H. pylori-positive moderate-severe atrophic gastritis and intestinal metaplasia, and 6 out of 8 cases with H. pylori-positive moderate-severe dysplasia. COX-2 expression was positive in 22 out of 32 cases of gastric cancer., Conclusion: H. pylori may induce COX-2 expression of gastric mucosal epithelia in chronic superficial gastritis, which is related to the development of mucosal injury. According to gastric mucosal carcinogenesis pattern up-regulation of COX-2 expression is associated with gastric mucosal carcinogenesis, and involved in the early development of premalignant lesions.

Lactic dehydrogenase (LDH) and its isoenzyme in the serum, gastric juice and mucosal tissue were studied in 83 patients with severe intestinal metaplasia, early and advanced gastric carcinoma, ulcer and superficial gastritis. The LDH activity in these tissues was lower in superficial gastritis and ulcer than in gastric carcinoma and intestinal metaplasia, while their isoenzyme activity was nearly normal. The LDH activity in the intestinal metaplasia was near to that in gastric carcinoma and its isoenzyme was transformed from H into M fraction, similar to gastric carcinoma. Thus, the relation between gastric carcinoma and intestinal metaplasia is reflected in the LDH activity. Because the differentiation of benign from malignant gastric disease by means of LDH assay is difficult and its isoenzyme possessing an individual characteristic distribution, this method may only be auxiliary in the differential diagnosis.