Enhancement in the protective qualities of gastric mucus with combination therapy of ebrotidine and amoxicillin for H. pylori eradication.

1. Gastric mucus from Helicobacter pylori-positive patients with active chronic gastritis type B, before and after successful combination therapy consisting of the H2 receptor antagonist ebrotidine (400 mg) and amoxicillin (1,000 mg) administered b.i.d., in the morning and at bedtime for a period of 2 weeks followed by administration of ebrotidine alone for the subsequent 4 weeks, was assessed for the changes in physicochemical properties associated with the mucosal protective potential and anti-H. pylori activity. 2. The results of physicochemical measurements revealed that eradication of H. pylori associated with the successful therapy for active chronic gastritis type B with ebrotidine-amoxicillin was accompanied by a 36% increase in gastric mucus hydrogen ion retardation capacity, a 1.5-2.1-fold increase in mucus gel viscosity and a 2.4-fold increase in its hydrophobicity. 3. The beneficial changes brought about by the ebrotidine-amoxicillin therapy in the physical properties of gastric mucus were also manifest in a 2.7-fold enhancement in the proportion of the high-molecular-weight polymeric mucin form responsible for the maintenance of gastric mucus gel integrity. 4. Moreover, assays of H. pylori aggregating titer of gastric mucus revealed that the successful combination therapy with ebrotidine and amoxicillin led to a 3.8-fold increase in mucin anti-H. pylori activity. 5. The results demonstrate that combination therapy with ebrotidine and amoxicillin for H. pylori eradication leads to a marked improvement in the protective qualities of gastric mucus essential for the preservation of mucosal integrity and enhances the inherent mucosal defense against H. pylori infection.

Role of sulfation in post-translational processing of gastric mucins.

1. Gastric mucosal segments were incubated in MEM supplemented with various sulfate concentrations in the presence of [3H]glucosamine, [3H]proline and [35S]Na2SO4, with and without chlorate, an inhibitor of 3'-phosphoadenosine-5'-phosphosulfate formation. 2. Incorporation of glucosamine and sulfate depended upon the sulfate content of the medium and reached a maximum at 300 microM sulfate. Introduction of chlorate into the medium, while having no effect on protein synthesis as evidenced by proline incorporation, caused, at its optimal concentration of 2 mM, a 90% decrease in mucin sulfation and a 40% drop in glycosylation. 3. At low sulfate content in the medium and in the presence of chlorate, the incorporation of sulfate and glucosamine was mainly into the low molecular-weight form of mucin. An increase in sulfate in the medium caused an increase in the high molecular-weight form of mucin and in the extent of sulfation in its carbohydrate chain. 4. The results suggest that the sulfation process is an early event taking place at the stage of mucin subunit assembly and that sulfate availability is essential for the formation of the high molecular-weight mucin polymer.

Role of sulphation in post-translational processing of rat salivary mucins.

Segments of rat submandibular salivary gland were incubated in MEM supplemented with 10-800 microM sulphate in the presence of [3H]-glucosamine, [3H]-proline and [35S]-Na2SO4, with 0-8 mM chlorate, an inhibitor of 3'-phosphoadenosine-5'-phosphosulphate formation. Incorporation of glucosamine and sulphate depended upon the sulphate content of the medium and reached a maximum at 400 microM sulphate. The introduction of chlorate into the medium, while having no effect on the protein synthesis as shown by [3H]-proline incorporation, caused, at its optimal concentration of 4 mM, a 90% decrease in mucin sulphation and a 29% drop in mucin glycosylation. At low sulphate content in the medium and in the presence of chlorate the incorporation of sulphate and glucosamine was mainly into the low molecular-weight form of mucin. An increase in sulphate in the medium caused an increase in the high molecular-weight form of mucin and in the extent of sulphation in its carbohydrate chain. This effect of sulphate was, however, inhibited by chlorate. The results suggest that sulphation takes place at an early stage of mucin assembly and that sulphate availability is essential for the formation of the high molecular-weight mucin.

Role of salivary epidermal growth factor in the maintenance of physicochemical characteristics of oral and gastric mucosal mucus coat.

The involvement of salivary epidermal growth factor (EGF) in the maintenance of oral and gastric mucosal mucus coat dimension and chemical characteristics was investigated using sialoadenectomized rats. Examination of the oral and gastric mucosal surface by phase contrast microscopy and Alcian blue uptake revealed that deprivation of salivary EGF caused a 31-36% reduction in mucus coat thickness and a 38-43% reduction in adherent mucin content. Chemical analyses indicated that the mucus coat of sialoadenectomized group exhibited a 21-28% increase in protein and a 67% decrease in covalently bound fatty acids, a 30% decrease in carbohydrates, and a 32-37% decrease in lipids. Sialoadenectomy also evoked changes in the chemical composition of mucus glycoprotein component of oral and gastric mucus coat reflected in the lower content of sulfate (25-26%), associated lipids (24-25%), and covalently bound fatty acids (67-75%). Intragastric supplementation of EGF had no effect on the physicochemical changes caused by sialoadenectomy in the oral mucosal mucus coat, while nearly complete restoration to normal characteristics occurred in the gastric mucosal mucus coat. The results suggest that salivary EGF is essential for the maintenance of mucus coat dimension and quality needed in the protection of alimentary tract epithelium.