A gentle optical examination of the mitochondrial permeability transition pore (mPTP) opening events was carried out in isolated quiescent ventricular myocytes by tracking the inner membrane potential (ΔΨ M) using TMRM (tetramethylrhodamine methyl ester). Zeiss Airyscan 880 "superresolution" or "high-resolution" imaging was done with very low levels of illumination (0.009% laser power). In cellular areas imaged every 9 seconds (ROI or regions of interest), transient depolarizations of variable amplitudes occurred at increasing rates for the first 30 minutes. The time to first depolarization events was 8.4 min (± 1.1 SEM n=21 cells). At longer times, essentially permanent and irreversible depolarizations occurred at an increasing fraction of all events. In other cellular areas surrounding the ROI, mitochondria were rarely illuminated (once per 5 minutes) and virtually no permanent depolarization events occurred for over 1 hour of imaging. These findings suggest that photon stress due to the imaging itself plays an important role in the generation of both the transient mPTP opening events as well as the permanent mPTP opening events. Consistent with the evidence that photon "stress" in mitochondria loaded with virtually any photon absorbing substance, generates reactive oxygen species (ROS) [1-5], we show that cyclosporine-A (CsA, 10 mM) and the antioxidant n-acetyl cysteine (NAC, 10 mM), reduced the number of events by 80 % and 93% respectively. Furthermore, CsA and NAC

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Microtubules tune cytoskeletal stiffness, which affects cytoskeletal mechanics and mechanotransduction of striated muscle. While recent evidence suggests that microtubules enriched in detyrosinated α-tubulin regulate these processes in healthy muscle and increase them in disease, the possible contribution from several other α-tubulin modifications has not been investigated. Here, we used genetic and pharmacologic strategies in isolated cardiomyocytes and skeletal myofibers to increase the level of acetylated α-tubulin without altering the level of detyrosinated α-tubulin. We show that microtubules enriched in acetylated α-tubulin increase cytoskeletal stiffness and viscoelastic resistance. These changes slow rates of contraction and relaxation during unloaded contraction and increased activation of NADPH oxidase 2 (Nox2) by mechanotransduction. Together, these findings add to growing evidence that microtubules contribute to the mechanobiology of striated muscle in health and disease.

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Interest in collaborative working has grown enormously in the last 20 years, driven by the view that partnership working may improve efficiency and add value in outcomes. As a result, collaborative working is an unavoidable feature of the 21st-century school and a consistent part of government policy for the provision of services to children. However, remarkably little research has been undertaken into the nature of leadership required to maximize the potential of such partnership based working within this context. This article outlines the findings from original research, supported by the National College for Leadership of Schools and Children’s Services, into the nature of effective collaborative leadership in schools. It finds that the demands of such leadership are markedly different from those associated with traditional models, which view the school in isolation. In response to this, it outlines a multi-dimensional model for leadership, which draws on elements of a range of existing leadership models, including authentic, relational, distributed, political and constitutive leadership. This article concludes by stating that it is only through the utilization of a blended form of leadership (Collinson and Collinson, 2006) that school leaders are able to effectively realize the potential collaborative advantage associated with partnerships working. In doing so, it highlights the significance of day-to-day leadership activity, stating that effective collaborative leadership is rooted in a focus on the mundane rather than a preoccupation with the extraordinary aspects of this role.