TAT-dextran-mediated mitochondrial transfer enhances recovery from models of reperfusion injury in cultured cardiomyocytes

Acute myocardial infarction is a leading cause of death among single organ diseases. Despite successful reperfusion therapy, ischaemia reperfusion injury (IRI) can induce oxidative stress (OS), cardiomyocyte apoptosis, autophagy and release of inflammatory cytokines, resulting in increased infarct size. In IRI, mitochondrial dysfunction is a key factor, which involves the production of reactive oxygen species, activation of inflammatory signalling cascades or innate immune responses, and apoptosis. Therefore, intercellular mitochondrial transfer could be considered as a promising treatment strategy for ischaemic heart disease. However, low transfer efficiency is a challenge in clinical settings. We previously reported uptake of isolated exogenous mitochondria into cultured cells through co-incubation, mediated by macropinocytosis. Here, we report the use of transactivator of transcription dextran complexes (TAT-dextran) to enhance cellular uptake of exogenous mitochondria and improve the protective effect of mitochondrial replenishment in neonatal rat cardiomyocytes (NRCMs) against OS. TAT-dextran-modified mitochondria (TAT-Mito) showed a significantly higher level of cellular uptake. Mitochondrial transfer into NRCMs resulted in anti-apoptotic capability and prevented the suppression of oxidative phosphorylation in mitochondria after OS. Furthermore, TAT-Mito significantly reduced the apoptotic rates of cardiomyocytes after OS, compared to simple mitochondrial transfer. These results indicate the potential of mitochondrial replenishment therapy in OS-induced myocardial IRI

小学校音楽授業における児童の自己効力感を実感させる授業実践に関する考察 ― 第１報：教師の指導言に着目して ―

　According to the new government course guidelines, to develop elementary school students’ ability to “enjoy” music, teachers are required to teach both knowledge and skills. This includes knowledge about motifs and structures of music and skills to express oneself musically. However, in reality, it is very difficult to offer classes that are enjoyable for students and that are not a mere self-satisfying set of instructions pertaining to knowledge and skills.　This study focuses on the impact of advice given by teachers to students in two sample music classes. The results show that the teachers’ positive remarks raised students’ enthusiasm, encouraging participation and helping students overcome difficulties. In addition to the teachers’ encouragements, focusing on class objectives neither negatively impacted students’ commitment to the classes nor understanding of the classes even when the content was challenging and not necessarily enjoyable

Low temperature heat capacity measurements of β−Si3N4β-Si_{3}N_{4} and γ−Si3N4γ-Si_{3}N_{4}: Determination of the equilibrium phase boundary between β−Si3N4β-Si_{3}N_{4} and γ−Si3N4γ-Si_{3}N_{4}

Isobaric heat capacities of β-Si$_{3}$N$_{4}$ and γ-Si$_{3}$N$_{4}$ were measured at temperatures between 1.8 and 309.9 K with a thermal relaxation method. The measured heat capacities of γ-Si$_{3}$N$_{4}$ are smaller than those of β-Si$_{3}$N$_{4}$ in this temperature range. Using these data, we determined the standard entropies of β-Si$_{3}$N$_{4}$ and γ-Si$_{3}$N$_{4}$ to be 62.30 J·mol$^{−1}$ K$^{−1}$ and 51.79 J·mol$^{−1}$ K$^{−1}$, respectively. The equilibrium phase boundary between β-Si$_{3}$N$_{4}$ and γ-Si$_{3}$N$_{4}$ was calculated using these values and thermodynamic parameters reported in previous studies. The obtained equilibrium phase transition pressure at 2000 K is 11.4 GPa. It is lower than the experimental pressures at which γ-Si$_{3}$N$_{4}$ was synthesized in previous studies. The calculated Clapeyron slope at this temperature is 0.6 MPa K$^{−1}$, which is consistent with those of theoretical studies

α-Melanocyte-stimulating hormone directly increases the plasma calcitonin level and involves calcium metabolism in goldfish

Abstract The effects of α-melanocyte-stimulating hormone (α-MSH) on calcium metabolism were examined with goldfish. The scales on the left side of goldfish bodies were removed to allow the regeneration of scales under anesthesia. Thereafter, the influences of α-MSH injection (low dose: 0.1 μg/g body weight; high dose: 1 μg/g body weight) on plasma calcitonin (calcium-regulating hormone) and the calcium content of the scales were investigated. Ten days after removing the scales, we measured the plasma calcitonin and calcium content of both regenerating scales on the left side and ontogenic scales on the right side. At both doses of α-MSH injection, plasma calcitonin concentrations in the α-MSH-treated group were significantly higher than those in the control group. The mRNA expressions of α-MSH-receptors were detected in the ultimobranchial glands (secretory organ of calcitonin), indicating that α-MSH directly functions in ultimobranchial glands and promotes calcitonin secretion. Furthermore, we found that the calcium content of regenerating scales in α-MSH-treated goldfish was higher than that in control goldfish, while the calcium content of ontogenic scales on the right side was significantly decreased by α-MSH injection. There was a significant co-relationship between plasma calcitonin and the calcium content of regenerating scales. The mRNA expression of calcitonin receptors in regenerating scales was remarkably higher than that in ontogenic scales. These results imply that calcitonin functions to promote scale regeneration resulting from the inhibition of bone resorption because calcitonin suppresses osteoclastic activity. Thus, we are the first to demonstrate the interaction between α-MSH and calcitonin in teleosts