1,834 research outputs found

    Comment on Principles of Cell Biology

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    Neurotrophic factors in the testis

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    Neurotrophic factors, interacting with neurons to affect their growth, are a subset of the polypeptide growth factors. There is increasing evidence for a broader physiological role of these factors which includes effects on a variety of nonneuronal tissues. Among the cell systems, where neurotrophic factors have been hypothesized to exert local nonneurotrophic activities, the testis is of particular interest. This organ represents a complex biological unit which requires the concerted action of very diverse cell types interacting with each other in order to ensure correct spermatogenesis. As signaling molecules that may be involved in these intercellular communication events, various neurotrophic factors have attained considerable scientific attention. This article intends to summarize the presently available data on the distribution and possible local activities of neurotrophic factors and their receptors in testicular cells and provides further information on local expression sites of some of these factors in the human testis.Biomedical Reviews 1999; 10: 25-30

    Dual nature of Leydig cells of the human testis

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    This review is devoted to the human Leydig cell, and systematizes published and own unpublished results from studies performed during the last decade. Leydig cells are the main cell type in the testis that produce androgens which are important for the development of the male genital organs, secondary sex characteristics and behavior as well as for the processing and maintenance of spermatogenesis. A lot of information accumulated provides evidence that Leydig cells of the human testis and the testis of some other species express or possess immunoreactivities for numerous marker substances characteristic for nerve and neuroendocrine cells. It is shown that human Leydig cells, beside of markers for steroidogenic activity, possess: neuronal markers, synaptic and storage vesicle proteins, neural cytoskeletal proteins, 5-hydroxytryptamine, enzymes involved in the synthesis of catecholamines, neurohormones and/or their receptors, neuropeptides, calcium-binding proteins, cell adhesion molecules, glial cell antigens, components of the nitric oxide/cyclic guanosine monophosphate system, components of the renin/angiotensin system, and numerous growth factors and their receptors. These results provide new evidence for the neuroendocrine nature of Leydig cells. As consequence, two main questions arise: (i) the origin of Leydig cells and (ii) their functional significance as neuroendocrine cells. The presumption that Leydig cells originate from mesenchymal-like cells of the mesonephros is the most common view in the literature. However, no data are provided concerning the origin of the stem cells from which the Leydig cell lineage develops. Mesenchyme comprises the embryonic connective tissue cells that may have mesodermal, ectodermal and neuroectodermal (neural crest) origin. In this relation and based on the recently established neuroendocrine feature, we speculate that Leydig stem cells may detach from unknown regions of the neural crest and migrate to the mesonephric and gonadal anlage at early stages of development. The functional significance of Leydig cells as neuroendocrine cells is also illustrated on the basis of the nitric oxide/cyclic guanosine monophosphate system. Accordingly, Leydig cells may regulate their steroidogenic activity by an intracrine or autocrine fashion. Furthermore, they are probably able to synchronize the activity of the cells in a Leydig cell cluster by a paracrine way. Leydig cells may influence the contractile activity of the smooth muscle cells of blood vessels, thus regulating the blood flow rate and the permeability for hormones and nutritive substances. Also, Leydig cells may regulate the contractile state of peritubular myofibroblasts and myofibroblasts and smooth muscle cells of the tunica albuginea. Similarly, Leydig cells may communicate with Sertoli cells and germ cells of the seminiferous tubules. Leydig cells are a relatively stable, heterogeneous population of cells in the human testis which persists even in cases of impaired spermatogenesis, fibrosis and different pathological changes of the testis. This fact suggests that Leydig cells survive under unusual conditions due to precise regulatory systems which make them to a larger extent independent from the local homeostasis.Biomedical Reviews 1996; 6: 11-41

    The Shifting Tides of Merger Litigation

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    In 2015, Delaware made several important changes to its laws concerning merger litigation. These changes, which were made in response to a perception that levels of merger litigation were too high and that a substantial proportion of merger cases were not providing value, raised the bar, making it more difficult for plaintiffs to win a lawsuit challenging a merger and more difficult for plaintiffs\u27 counsel to collect a fee award. We study what has happened in the courts in response to these changes. We find that the initial effect of the changes has been to decrease the volume of merger litigation, to increase the number of cases that are dismissed, and to reduce the size of attorneys\u27 fee awards. At the same time, we document an adaptive response by the plaintiffs\u27 bar. Merger cases are being filed in other state courts or in federal court, presumably in an effort to escape the application of the new Delaware rules. This responsive adaptation offers important lessons about the entrepreneurial nature of merger litigation and the limited ability of the courts to reduce the potential for litigation abuse. In particular, we find that plaintiffs\u27 attorneys respond rationally to these changes by shifting their filing patterns, and that defendants respond in kind. We argue, however, that more expansive efforts to shut down merger litigation, such as through the use of fee-shifting bylaws, are premature and create too great a risk of foreclosing beneficial litigation. We also examine Delaware\u27s dilemma in maintaining a balance between the rights of managers and shareholders in this area

    The Shifting Tides of Merger Litigation

    Get PDF
    In 2015, Delaware made several important changes to its laws concerning merger litigation. These changes, which were made in response to a perception that levels of merger litigation were too high and that a substantial proportion of merger cases were not providing value, raised the bar, making it more difficult for plaintiffs to win a lawsuit challenging a merger and more difficult for plaintiffs\u27 counsel to collect a fee award. We study what has happened in the courts in response to these changes. We find that the initial effect of the changes has been to decrease the volume of merger litigation, to increase the number of cases that are dismissed, and to reduce the size of attorneys\u27 fee awards. At the same time, we document an adaptive response by the plaintiffs\u27 bar. Merger cases are being filed in other state courts or in federal court, presumably in an effort to escape the application of the new Delaware rules. This responsive adaptation offers important lessons about the entrepreneurial nature of merger litigation and the limited ability of the courts to reduce the potential for litigation abuse. In particular, we find that plaintiffs\u27 attorneys respond rationally to these changes by shifting their filing patterns, and that defendants respond in kind. We argue, however, that more expansive efforts to shut down merger litigation, such as through the use of fee-shifting bylaws, are premature and create too great a risk of foreclosing beneficial litigation. We also examine Delaware\u27s dilemma in maintaining a balance between the rights of managers and shareholders in this area

    The Shifting Tides of Merger Litigation

    Get PDF
    In 2015, Delaware made several important changes to its laws concerning merger litigation. These changes, which were made in response to a perception that levels of merger litigation were too high and that a substantial proportion of merger cases were not providing value, raised the bar, making it more difficult for plaintiffs to win a lawsuit challenging a merger and more difficult for plaintiffs’ counsel to collect a fee award. We study what has happened in the courts in response to these changes. We find that the initial effect of the changes has been to decrease the volume of merger litigation, to increase the number of cases that are dismissed, and to reduce the size of attorneys’ fee awards. At the same time, we document an adaptive response by the plaintiffs’ bar in which cases are being filed in other state courts or in federal court in an effort to escape the application of the new rules. This responsive adaptation offers important lessons about the entrepreneurial nature of merger litigation and the limited ability of the courts to reduce the potential for litigation abuse. In particular, we find that plaintiffs’ attorneys respond rationally to these changes by shifting their filing patterns, and that defendants respond in kind. We argue, however, that more expansive efforts to shut down merger litigation, such as through the use of fee-shifting bylaws, are premature and create too great a risk of foreclosing beneficial litigation. We also examine Delaware’s dilemma in maintaining a balance between the rights of managers and shareholders in this area

    Publication guidelines for quality improvement in health care: evolution of the SQUIRE project

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    In 2005, draft guidelines were published for reporting studies of quality improvement interventions as the initial step in a consensus process for development of a more definitive version. This article contains the full revised version of the guidelines, which the authors refer to as SQUIRE (Standards for QUality Improvement Reporting Excellence). This paper also describes the consensus process, which included informal feedback from authors, editors and peer reviewers who used the guidelines; formal written commentaries; input from a group of publication guideline developers; ongoing review of the literature on the epistemology of improvement and methods for evaluating complex social programmes; a two-day meeting of stakeholders for critical discussion and debate of the guidelines’ content and wording; and commentary on sequential versions of the guidelines from an expert consultant group. Finally, the authors consider the major differences between SQUIRE and the initial draft guidelines; limitations of and unresolved questions about SQUIRE; ancillary supporting documents and alternative versions that are under development; and plans for dissemination, testing and further development of SQUIRE

    Easing the smart home: Translating human hierarchies to intelligent environments

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-02478-8_137Proceedings of 10th International Work-Conference on Artificial Neural Networks, IWANN 2009, Salamanca, Spain.Ubiquitous computing research have extended traditional environments in the so–called Intelligent Environments. All of them use their capabilities for pursuing their inhabitants’s satisfaction, but the ways of getting it are most of the times unclear and frequently unshared among different users. This last problem becomes patent in shared environments in which users with different preferences live together. This article presents a solution translating human hierarchies to the Ubicomp domain, in a continuing effort for leveraging the control capabilities of the inhabitants in their on–growing capable environments. This mechanism, as a natural ubicomp extension of the coordination mechanism used daily by humans, has been implemented over a real environment: a iving room equipped with ambient intelligence capabilities, and installed in two more: an intelligent classroom and an intelligent secure room.This work was partially funded by the Spanish Ministry of Science and Technology through the HADA project(TIN2007-64718) and by the chair UAM–Indra of Ambient Intelligenc
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