969 resultados para Mechanisms action


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Neutrophils serve as an intriguing model for the study of innate immune cellular activity induced by physiological stress. We measured changes in the transcriptome of circulating neutrophils following an experimental exercise trial (EXTRI) consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Blood samples were taken at baseline, 3 h, 48 h, and 96 h post-EXTRI from eight healthy, endurance-trained, male subjects. RNA was extracted from isolated neutrophils. Differential gene expression was evaluated using Illumina microarrays and validated with quantitative PCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Blood concentrations of muscle damage indexes, neutrophils, interleukin (IL)-6 and IL-10 were increased (P < 0.05) 3 h post-EXTRI. Upregulated groups of functionally related genes 3 h post-EXTRI included gene sets associated with the recognition of tissue damage, the IL-1 receptor, and Toll-like receptor (TLR) pathways (familywise error rate, P value < 0.05). The core enrichment for these pathways included TLRs, low-affinity immunoglobulin receptors, S100 calcium binding protein A12, and negative regulators of innate immunity, e.g., IL-1 receptor antagonist, and IL-1 receptor associated kinase-3. Plasma myoglobin changes correlated with neutrophil TLR4 gene expression (r = 0.74; P < 0.05). Neutrophils had returned to their nonactivated state 48 h post-EXTRI, indicating that their initial proinflammatory response was transient and rapidly counterregulated. This study provides novel insight into the signaling mechanisms underlying the neutrophil responses to endurance exercise, suggesting that their transcriptional activity was particularly induced by damage-associated molecule patterns, hypothetically originating from the leakage of muscle components into the circulation.

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The determinants and key mechanisms of cancer cell osteotropism have not been identified, mainly due to the lack of reproducible animal models representing the biological, genetic and clinical features seen in humans. An ideal model should be capable of recapitulating as many steps of the metastatic cascade as possible, thus facilitating the development of prognostic markers and novel therapeutic strategies. Most animal models of bone metastasis still have to be derived experimentally as most syngeneic and transgeneic approaches do not provide a robust skeletal phenotype and do not recapitulate the biological processes seen in humans. The xenotransplantation of human cancer cells or tumour tissue into immunocompromised murine hosts provides the possibility to simulate early and late stages of the human disease. Human bone or tissue-engineered human bone constructs can be implanted into the animal to recapitulate more subtle, species-specific aspects of the mutual interaction between human cancer cells and the human bone microenvironment. Moreover, the replication of the entire "organ" bone makes it possible to analyse the interaction between cancer cells and the haematopoietic niche and to confer at least a partial human immunity to the murine host. This process of humanisation is facilitated by novel immunocompromised mouse strains that allow a high engraftment rate of human cells or tissue. These humanised xenograft models provide an important research tool to study human biological processes of bone metastasis.

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This thesis focuses on non-Indigenous educators’ work around embedding Indigenous perspectives in early childhood education curricula. In place of reporting examples of ‘good’ educational practice, the study questions how whiteness and racism continue to operate in diversity work that is seen to be productive and inclusive. The thesis argues for a more comprehensive framework for embedding Indigenous perspectives in before-school contexts to support educators’ efforts. New strategies for professional development are also suggested to support changes in disciplinary knowledge and pedagogy.

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At a time when global consumption and production levels are 25 percent higher than the Earth’s sustainable carrying capacity, there are worldwide calls to find ways to sustain the Earth for this and future generations. A central premise of this study is that education systems have an obligation to participate in this move towards sustainability and can respond by embedding education for sustainability into curricula. This study took early childhood education as its focus due to the teacherresearcher’s own concerns about the state of the planet, coupled with early childhood education’s established traditions of nature-based and child-centred pedagogy. The study explored the experiences of a class of kindergarten children as they undertook a Project Approach to learning about environmental sustainability. The Project Approach is an adaptation of Chard’s work which is situated within a constructivist theoretical framework (Chard, 2011). The Project Approach involves in-depth investigations around an identified topic of interest. It has three phases: introductory, synthesising and culminating phase. The study also investigated the learning journey of the classroom teacher/researcher who broadened her long-held co-constructivist teaching approaches to include transformative practices in order to facilitate curriculum which embedded education for sustainability. While coconstructivist approaches focus on the co-construction of knowledge, transformative practices are concerned with creating change. An action research case study was conducted. This involved twenty-two children who attended an Australian kindergarten. Data were collected and analysed over a seven week period. The study found that young children can be change agents for sustainability when a Project Approach is broadened to include transformative practices. The study also found that the child participants were able to think critically about environmental and sustainability issues, were able to create change in their local contexts, and took on the role of educators to influence others’ environmental behaviours. Another finding was that the teacher-researcher’s participation in the study caused a transformation of both her teaching philosophy and the culture at the kindergarten. An important outcome of the study was the development of a new curriculum model that integrates and has applicability for curriculum development and teacher practice.

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This paper proposes an organisational effectiveness model that applies the theoretical frameworks of shared leadership, appreciative inquiry, and knowledge creation. Similar to many libraries worldwide, Auraria Library technical services department struggled to establish efficient and effective workflow for electronic resources management. The library purchased an Electronic Resource Management System, as the literature suggests; however, this technology-enabled system did not resolve workflow issues. The Auraria Library case study demonstrates that a technical services division can successfully reorganize personnel, reassign responsibilities, and measure outcomes within an evidencebased shared leadership culture, which invites and enables participants to identify problems and create solutions amidst a dynamically changing electronic resources environment.

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The Oceania region is an area particularly prone to natural disasters such as cyclones, tsunamis, floods, droughts, earthquakes and volcanic eruptions. Many of the nations in the region are Small Island Developing States (SIDS), yet even within wealthy states such as Australia and New Zealand there are groups which are vulnerable to disaster. Vulnerability to natural disaster can be understood in human rights terms, as natural disasters threaten the enjoyment of a number of rights which are guaranteed under international law, including rights to health, housing, food, water and even the right to life itself. The impacts of climate change threaten to exacerbate these vulnerabilities, yet, despite the foreseeability of further natural disasters as a result of climate change, there currently exists no comprehensive international framework for disaster response offering practical and/or legally reliable mechanisms to assist at‐risk states and communities. This paper sets out to explore the human rights issues presented by natural disasters and examine the extent to which these issues can be addressed by disaster response frameworks at the international, regional and national levels.

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Groundwater flow models are usually characterized as being either transient flow models or steady state flow models. Given that steady state groundwater flow conditions arise as a long time asymptotic limit of a particular transient response, it is natural for us to seek a finite estimate of the amount of time required for a particular transient flow problem to effectively reach steady state. Here, we introduce the concept of mean action time (MAT) to address a fundamental question: How long does it take for a groundwater recharge process or discharge processes to effectively reach steady state? This concept relies on identifying a cumulative distribution function, $F(t;x)$, which varies from $F(0;x)=0$ to $F(t;x) \to \infty$ as $t\to \infty$, thereby providing us with a measurement of the progress of the system towards steady state. The MAT corresponds to the mean of the associated probability density function $f(t;x) = \dfrac{dF}{dt}$, and we demonstrate that this framework provides useful analytical insight by explicitly showing how the MAT depends on the parameters in the model and the geometry of the problem. Additional theoretical results relating to the variance of $f(t;x)$, known as the variance of action time (VAT), are also presented. To test our theoretical predictions we include measurements from a laboratory–scale experiment describing flow through a homogeneous porous medium. The laboratory data confirms that the theoretical MAT predictions are in good agreement with measurements from the physical model.

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The Community Service-learning Lab (the Lab) was initiated as a university-wide service-learning experience at an Australian university. The Lab engages students, academics, and key community organisations in interdisciplinary action research projects to support student learning and to explore complex and ongoing problems nominated by the community partners. The current study uses feedback from the first offering of the Lab and focuses on exploring student experiences of the service learning project using an action research framework. Student reflections on this experience have revealed some positive outcomes of the Lab such as an appreciation for positive and strengths-based change. These outcomes are corroborated by collected reflections from community partners and academics. The students also identified challenges balancing the requirements for assessment and their goals to serve the community partner’s needs. This feedback has provided vital information for the academic team, highlighting the difficulties in balancing the agenda of the academic framework and the desire to give students authentic experiences.

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The first of three articles in this issue addressing the public space topic considers public space and young people in the light of a range of papers delivered at the 27th International Conference on 'Making Cities Livable', held in Vienna, Austria, in July 2000. Under the overarching concept of the "liveable city" the conference themes of 'Rediscovery of public space' and 'Cities for the wellbeing of children' attracted a broad mix of those interested in the planning, design and management of urban space. A number of themes percolated through the conference which stimulated the writers to examine the nexus between urban development, young people and public space. There is an ongoing need to examine the meaning of public space in the face of powerful urban development trends. A model of public space practice is required which incorporates a vision of inclusive public spaces, fosters the interactivity of design, planning, social policy and management, and resources for greater communication and strategic action between stake holders from the most local of levels to those at state and international levels. The speed and magnitude of contemporary urban development makes community input and influence difficult, particularly for those impacted on by the exclusionary tendencies of much urban development. It is critical that a range of meaningful and sustainable mechanisms are developed which allow young people’s conceptions of what constitutes youth-friendly space to be directly made and taken account of.

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Achilles tendinopathy is a common disorder involving physically active and sedentary individuals alike. Although the processes underlying its development are poorly understood, tendinopathy is widely regarded as an ‘overuse’ injury in which the tendon fails to adapt to prevalent loading conditions. Paradoxically, there is emerging evidence that heavy eccentric loading of the Achilles tendon may be an effective conservative approach for treatment of tendinopathy, with success rates of 60–80% reported. Interestingly, loading exercises involving other forms of muscle action, such as concentric activation, have been shown to be less effective treatment options. However, little is known about the acute response of tendon to exercise at present, and there are few plausible explanatory mechanisms for the observed beneficial effects of eccentric exercise, as opposed to other forms of strain stimuli. This paper presents the findings from a series of experiments undertaken to evaluate the effect of various strain stimuli on the time-dependent response of human Achilles tendon in vivo. It was shown for the first time, that heavy resistive ankle plantarflexion/ dorsiflexion exercises induced an immediate and significant decrease in Achilles tendon thickness (~15%). While thickness returned to pre-exercise levels within 24 hours, the recovery was exponential, with primary recovery occurring in less than 6 hours post-exercise. We proposed that such a diametral strain response with tensile loading reflects collagen realignment, Poison’s effects and radial extrusion of water from the tendon core. With unloading, the recovery of tendon dimensions likely reflects the re-diffusion of water via osmotic and/or inflammatory driven processes. Interestingly, prolonged walking was found to induce a similar diametral strain response. In subsequent studies, we demonstrated that eccentric exercise resulted in a greater reduction (-21%) in Achilles tendon thickness than isolated concentric exercise alone (-5%), despite a similar loading impulse. These novel findings, coupled with observations of a reduced diametral strain response with tendon pathology, highlight the importance of fluid movement to tendon function, nutrition and health. They also provide new insights into potential mechanisms underlying Achilles tendinopathy that impact rehabilitation strategies.