Effect of the Peptide Calcium Channel Blocker ω-hexatoxin-Hv1a on Cell Death during Ischemia/Reperfusion in vitro.

Apoptosis and necrosis during reperfusion after ischemia are key mechanisms at the cellular level leading to damage. The development of pathological conditions is preceded by intracellular calcium ion overload both at the stage of ischemia and at the stage of reperfusion. In this regard, one of the strategies aimed at reducing damage during ischemia/reperfusion is associated with the use of calcium channel blockers. The aim of the study was to study the effect of a peptide toxin, a calcium channel blocker ω-hexatoxin-Hv1a, on different types of epithelial cell death during in vitro reconstruction of ischemia/reperfusion conditions characteristic of organ transplantation. Materials and Methods: In this study, we used CHO-K1 epithelial cell culture. Changes in apoptosis, necrosis, cell index, and calcium ion concentration were assessed when modeling ischemia/reperfusion processes in vitro with the addition of a calcium channel blocker toxin. Ischemic and reperfusion injury was achieved by oxygen and nutrient deprivation followed by reperfusion in a complete nutrient medium. The measurements were performed using a multimodal plate reader-fluorimeter. Results: An increase in apoptosis, necrosis, and the concentration of calcium ions was recorded when modeling ischemia/reperfusion processes. A decrease in the level of apoptosis and necrosis, as well as the concentration of calcium ions to a physiological level or a level close to physiological, was noted when the toxin was added at a concentration of 50 nM at the reperfusion stage. The cell index showed a faster restoration in the presence of the toxin. Conclusion: The experimental data confirm the hypothesis of a beneficial effect of peptide calcium channel blockers on the state of epithelial cells during reperfusion after ischemia and can be considered for further study as a strategy for organ adaptation before reperfusion.

Thermal changes of the crystal structure and the influence of thermo-chemical annealing on the optical properties of YbAlO3 crystals.

The paper presents experimental results of investigations on the influence of temperature and thermo-chemical annealing on the structural and optical properties of YbAlO(3) crystals. Thermal behaviour of the crystal structure has been studied in the temperature range of 19-1173 K by means of in situ high-resolution x-ray powder diffraction using synchrotron radiation. Lattice expansion of YbAlO(3) displays a strongly anisotropic character: the relative expansion along the b direction is about two times smaller than that along the a and c axes. The influence of thermo-chemical annealing in oxidizing and reducing atmospheres has been studied by means of in situ optical spectroscopy. The increase of the absorption in the range of 300-600 nm during annealing in an oxidizing atmosphere as well as its bleaching during reduction has been observed in the temperature range 700-1000 K. The oxidation and reduction kinetics have been analysed by means of mathematical models taking into account diffusion and the quasi-chemical reaction of the defect centres.

Optical in situ study of the reduction/oxidation processes in YAlO(3):Mn crystals.

The paper presents experimental results on an in situ optical absorption study of the reduction/oxidation processes in YAlO(3):Mn crystals that are visible in the [Formula: see text] recharging of manganese ions. The appearance of the Mn(5+) absorption during annealing in an oxidizing atmosphere as well as its bleaching during annealing of the crystal in a reducing atmosphere have been studied in the temperature range from 800 to 1250 K. The oxidation and reduction kinetics are analyzed in the framework of the vacancies diffusion model and compared with the nominally pure and Nd-doped YAlO(3) crystals studied previously.