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Background: Despite the close association between gastric Helicobacter pylori infection and duodenal ulcer, little is known about how this organism may promote mucosal damage. A possibility might be that it produces, or induces the host to release, phospholipases that metabolize the protective layer of phospholipids., Methods: Aimed at determination of phospholipase A2 activity and the concentration of choline-containing phospholipids in gastric juice, aspirates were collected during gastroscopy in 38 consecutive referrals with either active (n = 19) or H. pylori-eradicated healed duodenal ulcer (n = 19)., Results: Gastric juice phospholipase A2 activity was 3.1 times higher in active than in healed duodenal ulcers (P = 0.03). Concurrently, the concentration of choline-containing phospholipids in the group with active ulcers was less than half compared with the healed group (P = 0.02)., Conclusion: The results indicate that phospholipase A2 activity and the concentration of choline-containing phospholipids in gastric juice are related to H. pylori status and duodenal ulcer disease.

The synthetic peptides AC-Glu-Phe-Phe (NO2)-Arg-amide (peptide VP) and AC-Ile-Glu-Phe-Phe (NO2)-Arg-amide (peptide VIP) are more readily hydrolyzed by human pepsin in gastric juice of patients of gastritis than those of duodenal ulcer and normal subjects. The kinetic parameters suggest that S3 subsite of the enzyme plays a role in the elevation of enzyme activity in gastric disease.

A superoxide dismutase (SOD) activity in saliva and gastric juice has been revealed using the NBT reduction and adrenaline autooxidation assays. This activity in saliva is induced mainly by enzymic mechanisms, whereas in gastric juice--by nonenzymic mechanisms. The gel chromatographic analysis of saliva has demonstrated the presence of several SOD isoenzymes. Nonenzymic mechanisms of the SOD activity in gastric juice involve the ionic activity of H+, Cu2+ and that of reduced glutathione. The SOD activity in gastric juice can be decreased by adding antacids and Fe ions. The effect of Fe3+ is found to be different depending on the methods of the SOD activity evaluation. Such metal-chelating agents as histidine and organic acids increase the SOD activity in gastric juice.

Lysozyme concentration in the gastric juice of 34 patients with peptic ulcer and 10 practically healthy persons was studied. In the patients with peptic ulcer the lysozyme levels in the gastric juice were found to be lower. A significant decrease in the lysozyme concentration was observed in the patients suffering from peptic ulcer for more than 2 years. During the first months of the disease increased levels of lysozyme were recorded. Relationship between the lysozyme concentration in the gastric juice and the acidity of the gastric contents was shown. Decreased concentrations of lysozyme were more pronounced in the patients with increased levels of hydrochloric acid.

Secretion patterns of gastric lipase and pepsin were studied in duodenal ulcer patients before and after vagotomy and in healthy subjects following continuous administration of pentagastrin in graded doses. The lipase output increased in response to pentagastrin stimulation in similar fashion as that of pepsin. The output of the two enzymes were correlated with each other and with hydrogen ion output. Evaluation of dose-response relationships showed that in duodenal ulcer patients the secretion of gastric lipase and pepsin is more sensitive to pentagastrin stimulation than that of hydrogen ions.

LDH is found in many body fluids and tissues. Its level is elevated in many diseases. Thus the levels of LDH in serum and gastric juice were determined in both benign and malignant disease of the upper gastro-intestinal tract using the spectrophotometric techniques. 45 patients were included in the study (duodenal ulcer 19; gastric ulcer 6; gastric polyps 5; and gastric carcinoma 15). Serum LDH levels were not significantly elevated. However, the gastric juice LDH levels were significantly elevated in gastric polyps and gastric carcinoma. The mean levels were 96.81 +/- 14.31 and 443.2 +/- 58.1 i.u./L respectively. Serial estimation of gastric juice LDH in patients with gastric polyps showed a remarkable elevation at the time of malignant transformation.

In an attempt to elucidate the etiology of acute gastric bleeding and/or erosion and chronic peptic ulcer, a measurement of gastric juice and mucosal pepsin was carried out in surgically-treated patients. Patients with massive gastric mucosal bleeding in the fundic gland area showed high levels of fundic mucosal pepsin without acid-pepsin appearance in the gastric contents. In these patients, a significantly high value of the peptic activity ratio of gastric mucosa to gastric juice (MJPR, 36.4 +/- 6.7) was observed. It can be suggested that transient blockage of pepsin output from peptic cells with occur in the course of the acute mucosal bleeding, while acid-peptic digestion could be carried out within the fundic gland mucosa. On the other hand, a close correlation between relatively high acid-and-pepsin concentration of the gastric contents and a low level of MJPR (5.6 +/- 1.2) was observed in patients with chronic gastric ulcer. Patients who had a gastric ulcer within the pyloric gland mucosa had a highest acid-peptic activity among three groups with ulcers in fundic gland area, border zone and pyloric gland area. There is a rule that acid-peptic activity becomes low when the site of gastric ulcer moves from pylorus to fundus. A marked increase in acid-and-pepsin secretion into the gastric cavity was observed in patients suffering from chronic duodenal ulcer showing the lowest level of MJPR (3.40 +/- 0.50).

The activity of beta-glucuronidase was studied in the gastric aspirate from normal individuals, cases of duodenal ulcer with pyloric stenosis and carcinoma of the stomach. The optimum pH for the activity of this enzyme in the gastric aspirate is 4.0 to 5.5. Cimetidine, a H2-receptor antagonist, was administered orally to obtain the optimum pH for the enzyme activity, when the pH of the gastric aspirate was less than 4.0. It is observed that the enzyme activity in cases of carcinoma of the stomach is markedly elevated (p less than 0.01), when compared with other cases in this study. It is suggested that the elevated enzyme activity in the gastric aspirate could be used as a biochemical marker in the diagnosis of carcinoma of the stomach.