950 resultados para Ca2 coordination


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We have developed a haptic-based approach for retraining of interjoint coordination following stroke called time-independent functional training (TIFT) and implemented this mode in the ARMin III robotic exoskeleton. The ARMin III robot was developed by Drs. Robert Riener and Tobias Nef at the Swiss Federal Institute of Technology Zurich (Eidgenossische Technische Hochschule Zurich, or ETH Zurich), in Zurich, Switzerland. In the TIFT mode, the robot maintains arm movements within the proper kinematic trajectory via haptic walls at each joint. These arm movements focus training of interjoint coordination with highly intuitive real-time feedback of performance; arm movements advance within the trajectory only if their movement coordination is correct. In initial testing, 37 nondisabled subjects received a single session of learning of a complex pattern. Subjects were randomized to TIFT or visual demonstration or moved along with the robot as it moved though the pattern (time-dependent [TD] training). We examined visual demonstration to separate the effects of action observation on motor learning from the effects of the two haptic guidance methods. During these training trials, TIFT subjects reduced error and interaction forces between the robot and arm, while TD subject performance did not change. All groups showed significant learning of the trajectory during unassisted recall trials, but we observed no difference in learning between groups, possibly because this learning task is dominated by vision. Further testing in stroke populations is warranted.

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The annexins, a family of Ca(2+)- and lipid-binding proteins, are involved in a range of intracellular processes. Recent findings have implicated annexin A1 in the resealing of plasmalemmal injuries. Here, we demonstrate that another member of the annexin protein family, annexin A6, is also involved in the repair of plasmalemmal lesions induced by a bacterial pore-forming toxin, streptolysin O. An injury-induced elevation in the intracellular concentration of Ca(2+) ([Ca(2+)](i)) triggers plasmalemmal repair. The highly Ca(2+)-sensitive annexin A6 responds faster than annexin A1 to [Ca(2+)](i) elevation. Correspondingly, a limited plasmalemmal injury can be promptly countered by annexin A6 even without the participation of annexin A1. However, its high Ca(2+) sensitivity makes annexin A6 highly amenable to an unproductive binding to the uninjured plasmalemma; during an extensive injury accompanied by a massive elevation in [Ca(2+)](i), its active pool is severely depleted. In contrast, annexin A1 with a much lower Ca(2+) sensitivity is ineffective at the early stages of injury; however, it remains available for the repair even at high [Ca(2+)](i). Our findings highlight the role of the annexins in the process of plasmalemmal repair; a number of annexins with different Ca(2+)-sensitivities provide a cell with the means to react promptly to a limited injury in its early stages and, at the same time, to withstand a sustained injury accompanied by the continuous formation of plasmalemmal lesions.

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Coordinating organizational activity across different sectors is crucial in disaster management. We analysed the response of 291 aid workers to the Haiti earthquake in 2010 and found that common incentives and a high degree of equality among aid organizations positively affected perceived network coordination. Large and public organizations were more likely to take leadership roles and high numbers of public organizations involved in the disaster response network led to improved network coordination. These results indicate the need for mechanisms that enable smaller and non-profit organizations to participate in network coordination and leadership.

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Cross-sectoral interorganizational relationships in post-conflict situations occur regularly. Whether formal task forces, advisory groups or other ad hoc arrangements, these relations take place in chaotic and dangerous situations with urgent and turbulent political, economic and social environments. Furthermore, they typically involve a large number of players from many different nations, operating across sectors, and between multiple layers of bureaucracy and diplomacy. The organizational complexity staggers many participants and observers, as do the tasks they are charged with completing. Reform efforts in Bosnia and Herzegovina starting in 1995 may serve as the archetype model of conflict, transition and development for the 21st century. It wins this honor due not to its particular programmatic successes and failures, rather to the interorganizational complexity of the International Community. From the massive response to the crisis, to the modern nation-building policies it spawned, and the development assistance practices and institutional arrangements it created, the Bosnian development experience has much to offer by way of lessons learned. This manuscript frames the unique Bosnian development situation, and provides lessons learned from the experience of nation building given local realities. Pettigrew (1992) called this "contextualizing." While network and/or organizational structure, strategy and process explain many interorganizational relationship issues, the development variables identified in this manuscript prove equally important, yet elusive and difficult to measure despite their very real and overt presence.