Adenosine deaminase activity in patients with the intestinal type of gastric carcinoma

Adenosine deaminase activity was studied in tissue slices taken endoscopically from gastric mucosa of patients with the intestinal type of gastric carcinoma. The enzyme activity was measured in mucosal homogenates by determination of ammonia liberated from substrate during 10-min incubation. It was found that: (1) the enzyme activity of de novo gastric cancer was significantly lower than that of recurrent cancer of the gastric remnant; and (2) the enzyme activity of uninvaded gastric mucosa surrounding the neoplastic lesion of non-operated stomach was significantly lower than of the gastric mucosa of partially resected stomach due to malignancy. Since the enzyme activity in gastric cancer and surrounding uninvaded gastric mucosa correlated well with the advance of neoplastic disease estimated by ultrasonography examination, we speculate that some systemic factors associated with tumor progression might be implicated in the regulation of adenosine deaminase activity.