901 resultados para yeast-to-hypha transition


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BACKGROUND: The prevalence of protein-energy malnutrition in older adults is reported to be as high as 60% and is associated with poor health outcomes. Inadequate feeding assistance and mealtime interruptions may contribute to malnutrition and poor nutritional intake during hospitalisation. Despite being widely implemented in practice in the United Kingdom and increasingly in Australia, there have been few studies examining the impact of strategies such as Protected Mealtimes and dedicated feeding assistant roles on nutritional outcomes of elderly inpatients. AIMS: The aim of this research was to implement and compare three system-level interventions designed to specifically address mealtime barriers and improve energy intakes of medical inpatients aged ≥65 years. This research also aimed to evaluate the sustainability of any changes to mealtime routines six months post-intervention and to gain an understanding of staff perceptions of the post-intervention mealtime experience. METHODS: Three mealtime assistance interventions were implemented in three medical wards at Royal Brisbane and Women's Hospital: AIN-only: Additional assistant-in-nursing (AIN) with dedicated nutrition role. PM-only: Multidisciplinary approach to meals, including Protected Mealtimes. PM+AIN: Combined intervention: AIN + multidisciplinary approach to meals. An action research approach was used to carefully design and implement the three interventions in partnership with ward staff and managers. Significant time was spent in consultation with staff throughout the implementation period to facilitate ownership of the interventions and increase likelihood of successful implementation. A pre-post design was used to compare the implementation and nutritional outcomes of each intervention to a pre-intervention group. Using the same wards, eligible participants (medical inpatients aged ≥65 years) were recruited to the preintervention group between November 2007 and March 2008 and to the intervention groups between January and June 2009. The primary nutritional outcome was daily energy and protein intake, which was determined by visually estimating plate waste at each meal and mid-meal on Day 4 of admission. Energy and protein intakes were compared between the pre and post intervention groups. Data were collected on a range of covariates (demographics, nutritional status and known risk factors for poor food intake), which allowed for multivariate analysis of the impact of the interventions on nutritional intake. The provision of mealtime assistance to participants and activities of ward staff (including mealtime interruptions) were observed in the pre-intervention and intervention groups, with staff observations repeated six months post-intervention. Focus groups were conducted with nursing and allied health staff in June 2009 to explore their attitudes and behaviours in response to the three mealtime interventions. These focus group discussions were analysed using thematic analysis. RESULTS: A total of 254 participants were recruited to the study (pre-intervention: n=115, AIN-only: n=58, PM-only: n=39, PM+AIN: n=42). Participants had a mean age of 80 years (SD 8), and 40% (n=101) were malnourished on hospital admission, 50% (n=108) had anorexia and 38% (n=97) required some assistance at mealtimes. Occasions of mealtime assistance significantly increased in all interventions (p<0.01). However, no change was seen in mealtime interruptions. No significant difference was seen in mean total energy and protein intake between the preintervention and intervention groups. However, when total kilojoule intake was compared with estimated requirements at the individual level, participants in the intervention groups were more likely to achieve adequate energy intake (OR=3.4, p=0.01), with no difference noted between interventions (p=0.29). Despite small improvements in nutritional adequacy, the majority of participants in the intervention groups (76%, n=103) had inadequate energy intakes to meet their estimated energy requirements. Patients with cognitive impairment or feeding dependency appeared to gain substantial benefit from mealtime assistance interventions. The increase in occasions of mealtime assistance by nursing staff during the intervention period was maintained six-months post-intervention. Staff focus groups highlighted the importance of clearly designating and defining mealtime responsibilities in order to provide adequate mealtime care. While the purpose of the dedicated feeding assistant was to increase levels of mealtime assistance, staff indicated that responsibility for mealtime duties may have merely shifted from nursing staff to the assistant. Implementing the multidisciplinary interventions empowered nursing staff to "protect" the mealtime from external interruptions, but further work is required to empower nurses to prioritise mealtime activities within their own work schedules. Staff reported an increase in the profile of nutritional care on all wards, with additional non-nutritional benefits noted including improved mobility and functional independence, and better identification of swallowing difficulties. IMPLICATIONS: The PhD research provides clinicians with practical strategies to immediately introduce change to deliver better mealtime care in the hospital setting, and, as such, has initiated local and state-wide roll-out of mealtime assistance programs. Improved nutritional intakes of elderly inpatients was observed; however given the modest effect size and reducing lengths of hospital stays, better nutritional outcomes may be achieved by targeting the hospital-to-home transition period. Findings from this study suggest that mealtime assistance interventions for elderly inpatients with cognitive impairment and/or functional dependency show promise.

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Enormous progress has been made towards understanding the role of specific factors in the process of epithelial-mesenchymal transition (EMT); however, the complex underlying pathways and the transient nature of the transition continues to present significant challenges. Targeting tumour cell plasticity underpinning EMT is an attractive strategy to combat metastasis. Global gene expression profiling and high-content analyses are among the strategies employed to identify novel EMT regulators. In this review, we highlight several approaches to systematically interrogate key pathways involved in EMT, with particular emphasis on the features of multiparametric, high-content imaging screening strategies that lend themselves to the systematic discovery of highly significant modulators of tumour cell plasticity.

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"Students transitioning from vocational education and training (VET) to university can experience a number of challenges. This small research project explored the information literacy needs of VET and university students and how they differ. Students studying early childhood related VET and university courses reported differences in how and where they searched for information in their studies. These differences reflect the more practical focus of VET compared with the more academic and theoretical approach of university. The author proposes a framework of support that could be provided to transitioning students to enable them to develop the necessary information literacy skills for university study."--publisher website

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As yet, there is no cure for metastatic breast cancer. Historically, considerable research effort has been concentrated on understanding the processes of metastasis, how a primary tumour locally invades and systemically disseminates using the phenotypic switching mechanism of epithelial to mesenchymal transition (EMT); however, much less is understood about how metastases are then formed. Breast cancer metastases often look (and may even function) as 'normal' breast tissue, a bizarre observation against the backdrop of the organ structure of the lung, liver, bone or brain. Mesenchymal to epithelial transition (MET), the opposite of EMT, has been proposed as a mechanism for establishment of the metastatic neoplasm, leading to questions such as: Can MET be clearly demonstrated in vivo? What factors cause this phenotypic switch within the cancer cell? Are these signals/factors derived from the metastatic site (soil) or expressed by the cancer cells themselves (seed)? How do the cancer cells then grow into a detectable secondary tumour and further disseminate? And finallyCan we design and develop therapies that may combat this dissemination switch? This review aims to address these important questions by evaluating long-standing paradigms and novel emerging concepts in the field of epithelial mesencyhmal plasticity.

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Epithelial-to-mesenchymal transition (EMT) processes endow epithelial cells with enhanced migratory/invasive properties and are therefore likely to contribute to tumor invasion and metastatic spread. Because of the difficulty in following EMT processes in human tumors, we have developed and characterized an animal model with transplantable human breast tumor cells (MDA-MB-468) uniquely showing spontaneous EMT events to occur. Using vimentin as a marker of EMT, heterogeneity was revealed in the primary MDA-MB-468 xenografts with vimentin-negative and vimentin-positive areas, as also observed on clinical human invasive breast tumor specimens. Reverse transcriptase-PCR after microdissection of these populations from the xenografts revealed EMT traits in the vimentin-positive zones characterized by enhanced 'mesenchymal gene' expression (Snail, Slug and fibroblast-specific protein-1) and diminished expression of epithelial molecules (E-cadherin, ZO-3 and JAM-A). Circulating tumor cells (CTCs) were detected in the blood as soon as 8 days after s.c. injection, and lung metastases developed in all animals injected as examined by in vivo imaging analyses and histology. High levels of vimentin RNA were detected in CTCs by reverse transcriptase-quantitative PCR as well as, to a lesser extent, Snail and Slug RNA. Von Willebrand Factor/vimentin double immunostainings further showed that tumor cells in vascular tumoral emboli all expressed vimentin. Tumoral emboli in the lungs also expressed vimentin whereas macrometastases displayed heterogenous vimentin expression, as seen in the primary xenografts. In conclusion, our data uniquely demonstrate in an in vivo context that EMT occurs in the primary tumors, and associates with an enhanced ability to intravasate and generate CTCs. They further suggest that mesenchymal-to-epithelial phenomena occur in secondary organs, facilitating the metastatic growth.

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Epithelial-to-mesenchymal transition (EMT) phenomena endow epithelial cells with enhanced migratory and invasive potential, and as such, have been implicated in many physiological and pathological processes requiring cell migration/invasion. Although their involvement in the metastatic cascade is still a subject of debate, data are accumulating to demonstrate the existence of EMT phenotypes in primary human tumors, describe enhanced metastatic potential of EMT derivatives in animal models, and report EMT attributes in circulating tumor cells (CTCs). The relationships between EMT and CTCs remain largely unexplored, and we review here in vitro and in vivo data supporting a putative role of EMT processes in CTC generation and survival.

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The possibility of effective control of the wetting properties of a nanostructured surface consisting of arrays of amorphous carbon nanoparticles capped on carbon nanotubes using the electrowetting technique is demonstrated. By analyzing the electrowetting curves with an equivalent circuit model of the solid/liquid interface, the long-standing problem of control and monitoring of the transition between the "slippy" Cassie state and the "sticky" Wenzel states is resolved. The unique structural properties of the custom-designed nanocomposites with precisely tailored surface energy without using any commonly utilized low-surface-energy (e.g., polymer) conformal coatings enable easy identification of the occurrence of such transition from the optical contrast on the nanostructured surfaces. This approach to precise control of the wetting mode transitions is generic and has an outstanding potential to enable the stable superhydrophobic capability of nanostructured surfaces for numerous applications, such as low-friction microfluidics and self-cleaning.

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In the built environment sector, a range of innovations are delivering environmental improvements with mixed success worldwide. The authors of this paper argue that a more “disruptive” form of innovation is needed to bring about significant and systemic change within the sector. Critical to this transition is the development of new behaviours and values. In particular, built environment professionals need to become active change agents in cultivating these new behaviours and values through the development of collaborative visions, scenarios, practices, and ideas. This paper identifies and discusses the critical role that design (in its broadest sense) can play in this process. Drawing on a comprehensive review of literature, the authors highlight a number of transformational opportunities for cross professional learning and sharing between design and built environment disciplines in achieving environmental innovation (eco-innovation). The paper also considers several design-based concepts that have a potential application in the built environment sector including: design thinking, social innovation (human-centered), and disruptive innovation (transformational) approaches. The research findings will assist in building the capabilities of designers and innovators to create sustainable solutions to global problems, and in supporting the social diffusion of systems-changing ideas in the built environment sector.

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Epithelial to mesenchymal transition (EMT) has gained widespread acceptance over recent years as a mechanism by which normally sessile epithelial tumour cells can move away from the primary tumour and metastasize. This review article examines the role of a number of growth factors in inducing EMT, and the reverse process mesenchymal to epithelial transition. Unique and common intracellular signalling pathways are highlighted. A comprehensive understanding of the regulation of EMT will be critical in manipulating this process to develop novel anti-metastasis therapies.

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This paper develops maximum likelihood (ML) estimation schemes for finite-state semi-Markov chains in white Gaussian noise. We assume that the semi-Markov chain is characterised by transition probabilities of known parametric from with unknown parameters. We reformulate this hidden semi-Markov model (HSM) problem in the scalar case as a two-vector homogeneous hidden Markov model (HMM) problem in which the state consist of the signal augmented by the time to last transition. With this reformulation we apply the expectation Maximumisation (EM ) algorithm to obtain ML estimates of the transition probabilities parameters, Markov state levels and noise variance. To demonstrate our proposed schemes, motivated by neuro-biological applications, we use a damped sinusoidal parameterised function for the transition probabilities.

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Industry-school partnerships (ISPs) are increasingly being recognised as a new way of providing vocational education opportunities. However, there is limited research investigating their impact on systemic (organisational and structural) and human resource (teachers and education managers) capacity to support school to work transitions. This paper reports on a government led ISP, established by the Queensland state government. ISPs across three industry sectors: minerals and energy; building and construction; and aviation are included in this study. This research adopted a qualitative case study methodology and draws upon boundary crossing theory to understand the dynamics of how each industry sector responded to systemic and human resource issues that emerged in each ISP. The main finding being that the systematic application of boundary crossing mechanisms by all partners pro-duced mutually beneficial outcomes. ISPs from the three sectors adopted different models, leveraged different boundary crossing objects but all maintained the joint vision and mutually agreed outcomes. All three ISPs genuinely crossed boundaries, albeit in different ways, and assisted teachers to co-pro-duce industry-based curriculums, share sector specific knowledge and skills that help enhance the school to work transition for school graduates.

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We investigate the evolution of the electronic structure across the insulator-metal transition in NiS2-xSex with changing composition, but in the absence of any structural or magnetic changes. A comparison of the inverse photoemission spectra with band-structure calculations establishes the importance of correlation effects in these systems. Systematic changes in the spectral distribution establish the persistence of the upper Hubbard band well into the metallic regime, with the insulator-to-metal transition being driven by a transfer of spectral weight from the Hubbard band to states close to the Fermi energy.

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The actin cytoskeleton is essential for a large variety of cell biological processes. Actin exists in either a monomeric or a filamentous form, and it is very important for many cellular functions that the local balance between these two actin populations is properly regulated. A large number of proteins participate in the regulation of actin dynamics in the cell, and twinfilin, one of the proteins examined in this thesis, belongs to this category. The second level of regulation involves proteins that crosslink or bundle actin filaments, thereby providing the cell with a certain shape. α-Actinin, the second protein studied, mainly acts as an actin crosslinking protein. Both proteins are conserved in organisms ranging from yeast to mammals. In this thesis, the roles of twinfilin and α-actinin in development were examined using Drosophila melanogaster as a model organism. Twinfilin is an actin monomer binding protein that is structurally related to cofilin. In vitro, twinfilin reduces actin polymerisation by sequestering actin monomers. The Drosophila twinfilin (twf) gene was identified and found to encode a protein functionally similar to yeast and mammalian twinfilins. A strong hypomorphic twf mutation was identified, and flies homozygous for this allele were viable and fertile. The adult twf mutant flies displayed reduced viability, a rough eye phenotype and severely malformed bristles. The shape of the adult bristle is determined by the actin bundles that are regularly spaced around the perimeter of the developing pupal bristles. Examination of the twf pupal bristles revealed an increased level of filamentous actin, which in turn resulted in splitting and displacement of the actin bundles. The bristle defect was rescued by twf overexpression in developing bristles. The Twinfilin protein was localised at sites of actin filament assembly, where it was required to limit actin polymerisation. A genetic interaction between twinfilin and twinstar (the gene encoding Cofilin) was detected, consistent with the model predicting that both proteins act to limit the amount of filamentous actin. α-Actinin has been implicated in several diverse cell biological processes. In Drosophila, the only function for α-actinin yet known is in the organisation of the muscle sarcomere. Muscle and non-muscle cells utilise different α-actinin isoforms, which in Drosophila are produced by alternative splicing of a single gene. In this work, novel α-actinin deletion alleles, including ActnΔ233, were generated, which specifically disrupted the transcript encoding the non-muscle α-actinin isoform. Nevertheless, ActnΔ233 homozygous mutant flies were viable and fertile with no obvious defects. By comparing α-actinin protein distribution in wild type and ActnΔ233 mutant animals, it could be concluded that non-muscle α-actinin is the only isoform expressed in young embryos, in the embryonic central nervous system and in various actin-rich structures of the ovarian germline cells. In the ActnΔ233 mutant, α-actinin was detected not only in muscle tissue, but also in embryonic epidermal cells and in certain follicle cell populations in the ovaries. The population of α-actinin protein present in non-muscle cells of the ActnΔ233 mutant is referred to as FC-α-actinin (Follicle Cell). The follicular epithelium in the Drosophila ovary is a well characterised model system for studies on patterning and morphogenesis. Therefore, α-actinin expression, regulation and function in this tissue were further analysed. Examination of the α-actinin localisation pattern revealed that the basal actin fibres of the main body follicle cells underwent an organised remodelling during the final stages of oogenesis. This involved the assembly of a transient adhesion site in the posterior of the cell, in which α-actinin and Enabled (Ena) accumulated. Follicle cells genetically manipulated to lack all α-actinin isoforms failed to remodel their cytoskeleton and translocate Ena to the posterior of the cell, while the actin fibres as such were not affected. Neither was epithelial morphogenesis disrupted. The reorganisation of the basal actin cytoskeleton was also disturbed following ectopic expression of Decapentaplegic (Dpp) or as a result of a heat shock. At late oogenesis, the main body follicle cells express both non-muscle α-actinin and FC-α-actinin, while the dorsal anterior follicle cells express only non-muscle α-actinin. The dorsal anterior cells are patterned by the Dpp and Epidermal growth factor receptor (EGFR) signalling pathways, and they will ultimately secrete the dorsal appendages of the egg. Experiments involving ectopic activation of EGFR and Dpp signalling showed that FC-α-actinin is negatively regulated by combined EGFR and Dpp signalling. Ubiquitous overexpression of the adult muscle-specific α-actinin isoform induced the formation of aberrant actin bundles in migrating follicle cells that did not normally express FC-α-actinin, provided that the EGFR signalling pathway was activated in the cells. Taken together, this work contributes new data to our knowledge of α-actinin function and regulation in Drosophila. The cytoskeletal remodelling shown to depend on α-actinin function provides the first evidence that α-actinin has a role in the organisation of the cytoskeleton in a non-muscle tissue. Furthermore, the cytoskeletal remodelling constitutes a previously undescribed morphogenetic event, which may provide us with a model system for in vivo studies on adhesion dynamics in Drosophila.

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We derive a very general expression of the survival probability and the first passage time distribution for a particle executing Brownian motion in full phase space with an absorbing boundary condition at a point in the position space, which is valid irrespective of the statistical nature of the dynamics. The expression, together with the Jensen's inequality, naturally leads to a lower bound to the actual survival probability and an approximate first passage time distribution. These are expressed in terms of the position-position, velocity-velocity, and position-velocity variances. Knowledge of these variances enables one to compute a lower bound to the survival probability and consequently the first passage distribution function. As examples, we compute these for a Gaussian Markovian process and, in the case of non-Markovian process, with an exponentially decaying friction kernel and also with a power law friction kernel. Our analysis shows that the survival probability decays exponentially at the long time irrespective of the nature of the dynamics with an exponent equal to the transition state rate constant.

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Recent reports provide evidence that the epithelial-to-mesenchymal transition (EMT) plays a key role in prostate cancer (PCa) metastasis and therapy resistance. We have recently identified the cell surface receptor, Neuropilin-1 (NRP1) to be increased during epithelial-mesenchymal transition (EMT) and this study aims to determine whether the inhibition of NRP1 will be a feasible therapeutic strategy for blocking PCa metastasis and therapy resistance.