Ultrastructural intestinal mucosa change after prolonged inhibition of gastric acid secretion by omeprazole in male rats

Current opinion on the regulation of small intestinal magnesium absorption

Magnesium (Mg²⁺) has an important role in numerous biological functions, and Mg²⁺ deficiency is associated with several diseases. Therefore, adequate intestinal absorption of Mg²⁺ is vital for health. The small intestine was previously thought to absorb digested Mg²⁺ exclusively through an unregulated paracellular mechanism, which is responsible for approximately 90% of total Mg²⁺ absorption. Recent studies, however, have revealed that the duodenum, jejunum, and ileum absorb Mg²⁺ through both transcellular and paracellular routes. Several regulatory factors of small intestinal Mg²⁺ uptake also have been explored, e.g., parathyroid hormone, fibroblast growth factor-23, apical acidity, proton pump inhibitor, and pH-sensing channel and receptors. The mechanistic factors underlying proton pump inhibitor suppression of small intestinal Mg²⁺, such as magnesiotropic protein dysfunction, higher mucosal bicarbonate secretion, Paneth cell dysfunction, and intestinal inflammation, are currently being explored. The potential role of small intestinal microbiomes in Mg²⁺ absorption has also been proposed. In this article, we reviewed the current knowledge on the mechanisms and regulatory factors of small intestinal Mg²⁺ absorption.

Analytical Evaluation of Wet and Dry Mechanochemical Syntheses of Calcium-Deficient Hydroxyapatite Containing Zinc Using X-ray Diffractometry and Near-Infrared Spectroscopy

Calcium-deficient zinc-containing calcium phosphate (ZnAP), which has sustained zinc release properties that are effective for treating osteoporosis, can be efficiently synthesized as a biomaterial through wet grinding. To elucidate the physicochemical mechanism of these mechanochemical syntheses, ground products were obtained from the starting material powder (S-CP), consisting of calcium hydrogen phosphate dihydrate (CHPD), calcium oxide (CaO), and zinc oxide (ZnO), by wet and dry grinding for 0–3 h in a centrifugal ball mill. The ground S-CP products were analyzed using powder X-ray diffraction (XRD) and near-infrared spectroscopy (NIRS); the crystal transformations and molecular interactions of the ground products were kinetically analyzed. The XRD and second-derivative NIRS results indicate that the S-CP is primarily transformed into ZnAP via amorphous solid formation in wet grinding, and the reaction follows a consecutive reaction model. In contrast, in dry grinding, the ground product of CHPD and CaO is transformed into an amorphous solid following an equilibrium reaction model; however, ZnO is predominantly not transformed and remains crystalline.

Mass spectrometric analysis of TRPM6 and TRPM7 from small intestine of omeprazole-induced hypomagnesemic rats

Disruption of small intestinal Mg²⁺ absorption has been reported as the underlying mechanism of proton pump inhibitor-induced hypomagnesemia (PPIH); hence, this study evaluated the expression, localization, phosphorylation, and oxidation of transient receptor potential melastatin 6 (TRPM6) and TRPM7 in the small intestine of rats subjected to PPIH. The expression and localization of cyclin M4 (CNNM4) was also analyzed. We show that, compared to control rats, membrane expression of the TRPM6/7 heterodimer and TRPM7 was markedly lower in the duodenum and the jejunum of PPIH rats; in contrast, expression of membrane TRPM6 and CNNM4 was higher in these organs. Mass spectrometric analysis of TRPM6 demonstrated hyper-phosphorylation, especially T1851, and hyper-oxidation at M1755, both of which can suppress its channel permeability. Further, hypo-phosphorylation of S141 and the dimerization motif domain of TRPM6 in PPIH rats might be involved in lower TRPM6/7 heterodimer expression. Hypo-phosphorylation, especially at S138 and S1360 in TRPM7 from PPIH rats disrupted stability of TRPM7 at the cell membrane; hyper-oxidation of TRPM7 was also observed. These results help explain the mechanism underlying the disruption of small intestinal Mg²⁺ absorption in PPIH.

Demographic, hematologic, and endoscopic differences between predominant corporeal and antral atrophic gastritis: A STROBE-Compliant study

ABSTRACT

The study aimed to assess demographic, clinical, and endoscopic parameters in patients with predominant corporeal atrophic gastritis (CAG) and enterochromaffin-like cell hyperplasia suggestive for autoimmune etiology in comparison with patients presenting Helicobacter pylori atrophic gastritis limited to the gastric antrum (AAG).Demographical, clinical, and pathological data of consecutive patients who underwent an upper digestive endoscopy for bleeding screening risk, symptoms, or anemia in a single endoscopy unit were retrieved. The final study group included 63 patients with CAG and enterochromaffin-like cell hyperplasia on histology and a control group of 142 patients with AAG.Female patients were predominant in the group with CAG versus AAG (69.8% vs 46.4%, P = .002). Microcytic anemia (P < .001), but not macrocytic anemia (P = .14) was associated with CAG, the mean corpuscular volume of erythrocyte (MCV) (82.5 vs 86.5 fl, P = .01), the mean value of serum iron (11.8 vs 14.3 μmol/L, P = .02), and hemoglobin level (11.0 vs 12.7 g/dL P < .01) being significantly lower in patients with CAG versus AAG. Upper digestive endoscopies with no visible mucosal lesions (P = .01) were also more frequent in the patients with CAG, but there were not differences regarding digestive symptoms between groups. The linear regression models revealed that the low hemoglobin (P < .001) and low MCV (P = .03) are the independent variables that can predict CAG on histology, but not the serum iron level (P = .77)Consecutive patients investigated on endoscopy with CAG in comparison with those having AAG are more frequent female, they have microcytic anemia, and no mucosal lesions on endoscopy. The decreased hemoglobin level and low MCV, rather than the serum iron level are predictors for CAG versus AAG on histology in endoscopic population.