ORNITHINE DECARBOXYLASE ACTIVITY IS A MARKER OF PREMALIGNANCY IN LONGSTANDING HELICOBACTER-PYLORI INFECTION

Background-Longstanding Helicobacter pylori infection may increase the risk of developing gastric adenocarcinoma. The sequence of chronic ac tive gastritis leading to gastritis with atrophy and subsequent intest inal metaplasia is thought to be a key step in gastric carcinogenesis. Ornithine decarboxylase (ODC) activity is increased in some pre-malig nant gastrointestinal conditions and is essential for malignant transf ormation in vitro. Aims-To measure ODC activity in the antrum of H pyl ori infected and noninfected subjects and to relate this to histologic al abnormalities associated with recent and longstanding H pylori infe ction. Methods-Six antral mucosal biopsy specimens were obtained from 75 patients for detailed histological assessment and measurement of OD C activity. Samples were measured in duplicate and results expressed a s median, interquartile range in pmol/mg protein/h. Results-ODC activi ty was significantly higher in H pylori positive (164, 88-259 pmol/mg/ h) than H pylori negative subjects (99 . 8, 55-158 pmol/mg/h, p=0 . 00 3). However the presence of gastritis, irrespective of the severity of inflammation or activity had no influence on ODC activity. Gastritis with atrophy was associated with increased ODC activity, which was clo sely related to the severity of the atrophy (p=0 . 01). Similarly, ODC activity was significantly increased in subjects with intestinal meta plasia (196, 83-25) compared with those without intestinal metaplasia (111 . 7, 65-175, p<0 . 04). Conclusions-These results indicate that t he histological changes associated with longstanding H pylori infectio n rather than inflammation alone are associated with increased polyami ne biosynthetic activity. This may be relevant to H pylori associated gastric carcinogenesis.