Preparation and luminescent properties of Eu-doped transparent mica glass-ceramics

Eu-doped transparent mica glass–ceramics were prepared, the influence of Eu-doping on the crystallization of the parent glasses was investigated and the luminescent properties of the parent glasses and the glass–ceramics were estimated. A small additive amount of Eu element was very effective in preparing transparent mica glass–ceramics. However, the excess addition led to the coarsening of phase separation in the glass phase and the separation of unidentified crystal phases and β-eucryptite during heating of the parent glasses, which caused white opaque at lower heating temperatures. When mica crystals were separated, Eu ions entered the interlayers of mica crystals. The observed emission and excitation spectra showed that parts of Eu³⁺ ions which were added as Eu₂O₃ were reduced to Eu²⁺ ions during melting of the starting materials and heating the parent glasses in air and the energy transfer from Eu²⁺ to Eu³⁺ ions occurred.ArticleCeramics International. 36(4):1303-1309 (2010)journal articl

Effects of chemical ischemia on purine nucleotides, free radical generation, lipids peroxidation and intracellular calcium levels in C 2C12 myotube derived from mouse myocytes

To elucidate the mechanisms of ischemia-mediated myopathy using in vitro model, changes of purine nucleotides, membrane lipid peroxidation(TBARS), intracellular calcium ([Ca2+]i)levels, generation of free radicals, and deoxyribonucleic acid (DNA) fragmentation were examined in mouse-derived C2C12 myotubes under the condition with an inhibition of glycolytic and oxidative metabolism as the ischemic condition. In purine nucleotides, intracellular adenosine triphosphate (ATP) and guanosine triphosphate (GTP) concentrations rapidly and significantly decreased after the treatment with ischemia. No remarkable differences were observed in other purine nucleotides, with the exception of inosine monophosphate (IMP) and extracellular hypoxanthine levels, both of which increased significantly during the ischemia. The lactate dehydrogenase activity in culture supernatant of C2C12 myotubes increased significantly from 2 to 4 hr after the ischemia. On the generation of free radicals, no spectrum was detected in supernatants throughout the observation period, whereas supernatant TBARS concentration increased rapidly and significantly after the ischemia. The relative intensity of [Ca2+]i significantly increased after the ischemia. On the fragmented deoxyribonucleic acid(DNA), no TUNEL positive cells was detected in C2C12 myotubes after 1 hr of the ischemia, however the positive cell percentage subsequently increased. From these results, it was suggested that the ischemic condition induced changes of membrane permeability and increase of [Ca2+]i, both of which lead to cell membrane damage, although a free radical generation was not detected. The ischemic condition also induced the release of substrate hypoxanthine for free radical generation and might initiate the apoptotic pathway in C2C12 myotubes.Facultad de Ciencias Veterinaria

Effects of chemical ischemia on purine nucleotides, free radical generation, lipids peroxidation and intracellular calcium levels in C 2C12 myotube derived from mouse myocytes

To elucidate the mechanisms of ischemia-mediated myopathy using in vitro model, changes of purine nucleotides, membrane lipid peroxidation(TBARS), intracellular calcium ([Ca2+]i)levels, generation of free radicals, and deoxyribonucleic acid (DNA) fragmentation were examined in mouse-derived C2C12 myotubes under the condition with an inhibition of glycolytic and oxidative metabolism as the ischemic condition. In purine nucleotides, intracellular adenosine triphosphate (ATP) and guanosine triphosphate (GTP) concentrations rapidly and significantly decreased after the treatment with ischemia. No remarkable differences were observed in other purine nucleotides, with the exception of inosine monophosphate (IMP) and extracellular hypoxanthine levels, both of which increased significantly during the ischemia. The lactate dehydrogenase activity in culture supernatant of C2C12 myotubes increased significantly from 2 to 4 hr after the ischemia. On the generation of free radicals, no spectrum was detected in supernatants throughout the observation period, whereas supernatant TBARS concentration increased rapidly and significantly after the ischemia. The relative intensity of [Ca2+]i significantly increased after the ischemia. On the fragmented deoxyribonucleic acid(DNA), no TUNEL positive cells was detected in C2C12 myotubes after 1 hr of the ischemia, however the positive cell percentage subsequently increased. From these results, it was suggested that the ischemic condition induced changes of membrane permeability and increase of [Ca2+]i, both of which lead to cell membrane damage, although a free radical generation was not detected. The ischemic condition also induced the release of substrate hypoxanthine for free radical generation and might initiate the apoptotic pathway in C2C12 myotubes.Facultad de Ciencias Veterinaria