Gastric secretion

[Computer search for molecular mechanisms of ulcerogenic action of nonsteroidal antiinflammatory drugs]

"Peptic ulcers" is the most frequent side effect of non-steroidal anti-inflammatory drugs (NSAIDs). Experimental data indicate that pathogenesis of peptic ulcers cannot be explained only by the inhibition of cyclooxygenases. The knowledge about other molecular mechanisms of action of drugs related with development of peptic ulcers could be useful for design of new safe NSAIDs. However, considerable time and material resources are needed for corresponding experimental research. For simplification of experimental search, we have developed an approach for in silico identification of probable molecular mechanisms of action of drugs related with its side effects. We have created the set of NSAIDs containing 85 substances with data about structures and side effects. The computer program PASS (Prediction of Activity Spectra for Substances) predicting more than 3000 molecular mechanisms of action based on structural formula of substances was used to estimate unknown molecular mechanisms of action for these set of NSAIDs. Statistically significant relationships between predicted molecular mechanisms of action and development of peptic ulcers have been established. We have discovered twenty-six molecular mechanisms of action (two known previously and twenty-four new) which probably related with development of peptic ulcers. By analyzing of Gene Ontology data, signal and metabolic pathways, publications in Medline, we formulated hypotheses about the role of ten molecular mechanisms of action in pathogenesis of peptic ulcer.

Effect of Helicobacter pylori infection and its eradication on reflux esophagitis and reflux symptoms

OBJECTIVES

We evaluated the association between current Helicobacter pylori infection and reflux esophagitis and the effect of H. pylori eradication on reflux esophagitis in a healthy screening population.

METHODS

A total of 10,102 subjects in a comprehensive screening cohort were enrolled, and 4,007 subjects had follow-up after a median of 2 years. Effects of H. pylori infection on reflux esophagitis were estimated with odds ratios (ORs) and 95% confidence intervals (CIs) using multiple logistic regression analysis. We evaluated the change in prevalence of reflux esophagitis and reflux symptoms after H. pylori eradication vs. persistence.

RESULTS

The prevalence of reflux esophagitis (as classified by the Los Angeles system) was 4.9% (490/10,102). Whereas the prevalence of reflux esophagitis was 6.4% (319/4,971) in subjects without H. pylori infection, it was 3.3% (171/5,131) in subjects with infection (P<0.001). H. pylori infection had a strong negative association with reflux esophagitis in multivariate analysis (OR 0.42; 95% CI, 0.34-0.51). Compared with the prevalence of reflux esophagitis in the persistent infection group, the prevalence of reflux esophagitis increased after successful H. pylori eradication (OR 2.34; 95% CI, 1.45-3.76; P<0.001), which was comparable to that of the H. pylori-negative group (OR 2.42; 95% CI, 1.73-3.36; P<0.001). However, reflux symptoms had no association with H. pylori infection or eradication.

CONCLUSIONS

In a healthy screening population, H. pylori infection had a strong negative association with reflux esophagitis, but H. pylori eradication increased the prevalence of erosive esophagitis to the level of H. pylori-negative individuals. Long-term clinical significance of newly developed erosive esophagitis after H. pylori eradication should be evaluated prospectively.

Phytochemical Analyses and Gastroprotective Effects of Eugenia Umbelliflora (Myrtaceae) on Experimental Gastric Ulcers

Phytochemical studies of Eugenia umbelliflora Berg. (Myrtaceae) resulted in the isolation of: taraxerol, α-amyrin, β-amyrin, betulin and betulinic acid from the leaves, as well as trimethoxy ellagic acid from the fruits. Given that several triterpenes were found in the extracts, and that these possess gastroprotective activity, the gastroprotective activity of E. umbelliflora leaf extract was evaluated using ethanol, indomethacin, and stress-induced ulcer models in mice. The crude methanol extract was administrated (v.o) in doses of 50, 125 and 250 mg/kg. The results showed that E. umbelliflora leaves display gastroprotective activity, as demonstrated by significant inhibition of ulcer formation in the different models. The results suggest that the gastroprotective activity may be attributed, at least in part, to the triterpenes.

Antiulcerogenic activity of a crude hydroalcoholic extract and coumarin isolated from Mikania laevigata Schultz Bip

The leaves of Mikania (Asteraceae) species are used in folk medicine as antispasmodic, antiulcerogenic and antirheumatic agents. Phytochemical screening of the crude hydroalcoholic 70% extract (CHE) of Mikania laevigata Shultz Bip. revealed coumarins, terpenes and organic acids. Antiulcerogenic activity of CHE was evaluated, employing different experimental models in rats, to discern the pharmacological mechanism of action. Both the antisecretory and the cytoprotection hypothesis were evaluated. The crude hydroalcoholic extract (1000 mg/kg body wt., vo) decreased the ulcerative lesion index produced by indomethacin, ethanol, stress and reserpine in rats by 85%, 93%, 82% and 50%, respectively. In the pyloric ligation model, a decrease of hydrogenionic concentration (53%) was observed, suggesting that the pharmacological mechanism has a relationship to antisecretory activity. The antisecretory mechanisms of CHE and the coumarin isolated from M. laevigata were confirmed by acid hypersecretion induced by histamine, pentagastrin and bethanechol. Duodenal administration of CHE (1000 mg/kg body wt.) and coumarin (100 mg/kg body wt.) inhibited only the gastric acid secretion produced by bethanecol. These results suggest that both CHE and coumarin may influence the secretion control mediated by the parasympathetic system.