Characterizing Grain Boundary Effects on Mg Conduction in Metal-Organic Frameworks.

Next-generation materials for fast ion conduction have the potential to revolutionize battery technology. Metal-organic frameworks (MOFs) are promising candidates for achieving this goal. Given their structural diversity, the design of efficient MOF-based conductors can be accelerated by a detailed understanding and accurate prediction of ion conductivity.

Function and structure of parietal cells after H+-K+-ATPase blockade.

Omeprazole was administered to rabbits as a single dose or daily for 1 wk. H+-K+-ATPase and isolated gastric glands were prepared from the oxyntic corpus mucosa and used for functional and quantitative morphological studies. Both 10 and 100 mumol omeprazole/kg increased the pH of the gastric content when measured at death.

Histamine H2-receptor of human and rabbit parietal cells.

The histamine H2-receptor on the human parietal cell has been characterized by using dose-response curves and the negative logarithm of the molar concentration of an antagonist (pA2) analyses of cimetidine antagonism of betazole, histamine, and impromidine stimulation in isolated human and rabbit gastric glands. To evaluate the in vitro results, betazole-stimulated gastric acid secretion with and without cimetidine was also studied in healthy subjects. In the in vivo model, individual dose-response curves were shifted to the right with increasing cimetidine concentrations, but this was counteracted by increasing betazole doses, indicating competitive, reversible antagonism.

Inhibitory action of omeprazole on acid formation in gastric glands and on H+,K+-ATPase isolated from human gastric mucosa.

The inhibitory effect of omeprazole on acid formation has been studied in vitro in gastric glands and partly purified H+,K+-ATPase, prepared from mucosa obtained either from healthy subjects by gastroscopic biopsy or from gastric ulcer patients during antrectomy. The effect of omeprazole was compared with the inhibitory pattern of the H2-antagonist cimetidine. Acid production in the glands was determined by measuring the accumulation of 14C-aminopyrine.

Acid secretion in isolated gastric glands from healthy subjects and ulcer patients.

Isolated human gastric glands provide an in vitro model that can yield significant information about the mechanisms regulating gastric acid secretion at the parietal cell level. Aminopyrine, a weak base that accumulates in acid compartments, has been used as an indirect probe of H+ secretion. By means of a microscale technique it was possible to isolate oxyntic glands from gastroscopic biopsy specimens and thereby enable studies of healthy subjects and non-operated ulcer patients.

Effects of proximal gastric vagotomy and antrectomy on parietal cell function in humans.

Both proximal gastric vagotomy and antrectomy reduce maximal gastric acid secretion in vivo by about 60%. The combination of vagotomy and antrectomy reduces the maximal acid secretion by about 80%. This additive effect indicates that these surgical procedures differ in their mode of action.

Inhibition of acid secretion in isolated gastric glands by substituted benzimidazoles.

A new class of gastric acid inhibitors, substituted benzimidazoles (H 83/69 and H 149/94), have been tested in an isolated rabbit gastric gland preparation. Acid formation in the glands was stimulated by histamine, dibutyryl cAMP (DBcAMP), and high extracellular K+ concentrations, and the glandular secretory response was measured by changes in oxygen consumption and in accumulation of the weak base [14C]aminopyrine (AP). The substituted benzimidazoles inhibited AP accumulation induced by all stimulants in a dose-dependent noncompetitive manner.

The effects of secretagogues of isolated human gastric glands.

The function of isolated human gastric glands has been studied in vitro by measuring the 14C-aminopyrine accumulation (RAP) in basal, unstimulated, conditions and after stimulation with different secretagogues. A microscale technique was used which enabled determinations of RAP in tissue obtained as gastroscopic biopsies. In addition, oxyntic-gland-containing mucosa was obtained at gastric resections for gastric or prepyloric ulcer disease.

Acid secreting gastric heterotopia in the duodenum.

Heterotopic gastric mucosa was found in the duodenum of a female patient with duodenitis and acid hyposecretion. The heterotopic isolated fundic glands were shown to accumulate 14C-aminopyrine in basal state and on stimulation with histamine suggesting that the heterotopic mucosa secreted acid. The ectopic acid secretion in the duodenal bulb suppressed gastric acid secretion, and might have caused the duodenitis and at least partly the clinical symptoms.

Substituted benzimidazoles inhibit gastric acid secretion by blocking (H+ + K+)ATPase.

Studies both in vivo and in vitro have shown that substituted benzimidazoles inhibit the stimulation of acid secretion produced by dibutyryl cyclic AMP and histamine. Furthermore, the results differ from those produced by H2 antagonists and anticholinergic agents in that the inhibition is not competitive, and the site of action is intracellular and peripheral to that of dibutyryl cyclic AMP. To investigate the biochemical mechanism of action of substituted benzimidazoles, one such compound, H 149/94 (2-([2-(3-methyl)pyridyl-methyl]-sulphinyl)-5-methoxycarbonyl-6-methylbenzimidazol), has been tested either directly on an (H+ + K+)ATPase isolated from pig and human gastric mucosa or on the function of this enzyme in gastric glands isolated from rabbit and human gastric mucosa.