1,037 research outputs found

    Facilitating children's self-concept: A rationale and evaluative study

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    This study reports on the design and effectiveness of the Exploring Self-Concept program for primary school children using self-concept as the outcome measure. The program aims to provide a procedure that incorporates organisation, elaboration, thinking, and problem-solving strategies and links these to children's multidimensional self-concept. The results of this research support the notion that teachers and guidance counsellors need to establish a nonthreatening framework that allows them to discuss with children a range of relevant issues related to peer pressure, parent relations, self-image, body image, gender bias, media pressure, values and life goals, in a systematic, objective and cooperative manner. Within the paper, notions associated with self-concept maturation, 'crystallisation' of self-concept beliefs, cognitive differentiation and self-concept segmentation are reviewed

    FusC, a member of the M16 protease family acquired by bacteria for iron piracy against plants.

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    Iron is essential for life. Accessing iron from the environment can be a limiting factor that determines success in a given environmental niche. For bacteria, access of chelated iron from the environment is often mediated by TonB-dependent transporters (TBDTs), which are β-barrel proteins that form sophisticated channels in the outer membrane. Reports of iron-bearing proteins being used as a source of iron indicate specific protein import reactions across the bacterial outer membrane. The molecular mechanism by which a folded protein can be imported in this way had remained mysterious, as did the evolutionary process that could lead to such a protein import pathway. How does the bacterium evolve the specificity factors that would be required to select and import a protein encoded on another organism's genome? We describe here a model whereby the plant iron-bearing protein ferredoxin can be imported across the outer membrane of the plant pathogen Pectobacterium by means of a Brownian ratchet mechanism, thereby liberating iron into the bacterium to enable its growth in plant tissues. This import pathway is facilitated by FusC, a member of the same protein family as the mitochondrial processing peptidase (MPP). The Brownian ratchet depends on binding sites discovered in crystal structures of FusC that engage a linear segment of the plant protein ferredoxin. Sequence relationships suggest that the bacterial gene encoding FusC has previously unappreciated homologues in plants and that the protein import mechanism employed by the bacterium is an evolutionary echo of the protein import pathway in plant mitochondria and plastids

    Modelling Hepatic Endoderm Development: Highly Efficient Differentiation of Human Embryonic Stem Cells to Functional Hepatic Endoderm Requires ActivinA and Wnt3a Signalling.

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    Human embryonic stem cells (hESCs) are a valuable source of pluripotential primary cells. However, their homogeneous cellular differentiation to specific cell types _in vitro_ has proven difficult thus far. Wnt signalling has been shown to play important roles in coordinating development and we demonstrate that Wnt3a is differentially expressed at critical stages of human liver development _in vivo_. The essential role of Wnt3a in hepatocyte differentiation from hESCs is paralleled by our _in vitro_ model, demonstrating the importance of a physiological approach to cellular differentiation. Our studies provide compelling evidence that Wnt3a signaling is important for coordinated hepato-cellular function _in vitro_ and _in vivo_. In addition, we demonstrate Wnt3a facilitates clonal plating of hESCs capable of hepatic endoderm differentiation. These studies represent an important step forward toward the use of hESC-derived hepatocytes in biomedical applications and has opened the door to high through-put metabolic analysis of human liver function

    Regionalism and African agency : negotiating an Economic Partnership Agreement between the European Union and SADC-Minus

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    This article investigates the regional dynamics of African agency in the case of negotiations for an Economic Partnership Agreement (EPA) between the EU and a group of Southern African countries, known as SADC-Minus. I argue that these negotiations were shaped by a pattern of differentiated responses to the choice set on offer under the EPAs by SADC-Minus policymakers and by a series of strategic interactions and power plays between them. I offer two contributions to an emerging literature on the role of African agency in international politics. First, I argue for a clear separation between ontological claims about the structure-agency relationship and empirical questions about the preferences, strategies and influence of African actors. Second, I suggest that in order to understand the regional dynamics of African agency it is important to pay close attention to the diversity and contingency of African preferences and to the role of both power politics and rhetorical contestation in regional political processes

    The science of clinical practice: disease diagnosis or patient prognosis? Evidence about "what is likely to happen" should shape clinical practice.

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    BACKGROUND: Diagnosis is the traditional basis for decision-making in clinical practice. Evidence is often lacking about future benefits and harms of these decisions for patients diagnosed with and without disease. We propose that a model of clinical practice focused on patient prognosis and predicting the likelihood of future outcomes may be more useful. DISCUSSION: Disease diagnosis can provide crucial information for clinical decisions that influence outcome in serious acute illness. However, the central role of diagnosis in clinical practice is challenged by evidence that it does not always benefit patients and that factors other than disease are important in determining patient outcome. The concept of disease as a dichotomous 'yes' or 'no' is challenged by the frequent use of diagnostic indicators with continuous distributions, such as blood sugar, which are better understood as contributing information about the probability of a patient's future outcome. Moreover, many illnesses, such as chronic fatigue, cannot usefully be labelled from a disease-diagnosis perspective. In such cases, a prognostic model provides an alternative framework for clinical practice that extends beyond disease and diagnosis and incorporates a wide range of information to predict future patient outcomes and to guide decisions to improve them. Such information embraces non-disease factors and genetic and other biomarkers which influence outcome. SUMMARY: Patient prognosis can provide the framework for modern clinical practice to integrate information from the expanding biological, social, and clinical database for more effective and efficient care

    Lineage-specific distribution of high levels of genomic 5-hydroxymethylcytosine in mammalian development

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    Methylation of cytosine is a DNA modification associated with gene repression. Recently, a novel cytosine modification, 5-hydroxymethylcytosine (5-hmC) has been discovered. Here we examine 5-hmC distribution during mammalian development and in cellular systems, and show that the developmental dynamics of 5-hmC are different from those of 5-methylcytosine (5-mC); in particular 5-hmC is enriched in embryonic contexts compared to adult tissues. A detectable 5-hmC signal appears in pre-implantation development starting at the zygote stage, where the paternal genome is subjected to a genome-wide hydroxylation of 5-mC, which precisely coincides with the loss of the 5-mC signal in the paternal pronucleus. Levels of 5-hmC are high in cells of the inner cell mass in blastocysts, and the modification colocalises with nestin-expressing cell populations in mouse post-implantation embryos. Compared to other adult mammalian organs, 5-hmC is strongly enriched in bone marrow and brain, wherein high 5-hmC content is a feature of both neuronal progenitors and post-mitotic neurons. We show that high levels of 5-hmC are not only present in mouse and human embryonic stem cells (ESCs) and lost during differentiation, as has been reported previously, but also reappear during the generation of induced pluripotent stem cells; thus 5-hmC enrichment correlates with a pluripotent cell state. Our findings suggest that apart from the cells of neuronal lineages, high levels of genomic 5-hmC are an epigenetic feature of embryonic cell populations and cellular pluri- and multi-lineage potency. To our knowledge, 5-hmC represents the first epigenetic modification of DNA discovered whose enrichment is so cell-type specific

    Using participatory design methodologies to co-design and culturally adapt the Spanish version of the Mental Health eClinic: Qualitative study

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    Background: The Mental Health eClinic (MHeC) aims to deliver best-practice clinical services to young people experiencing mental health problems by making clinical care accessible, affordable, and available to young people whenever and wherever they need it most. The original MHeC consists of home page with a visible triage system for those requiring urgent help; a online physical and mental health self-report assessment; a results dashboard; a booking and videoconferencing system; and the generation of a personalized well-being plan. Populations who do not speak English and reside in English-speaking countries are less likely to receive mental health care. In Australia, international students have been identified as disadvantaged compared with their peers; have weaker social support networks; and have higher rates of psychological distress. This scenario is acquiring significant relevance as Spanish-speaking migration is rapidly growing in Australia, and the mental health services for culturally and linguistically diverse populations are limited. Having a Spanish version (MHeC-S) of the Mental Health eClinic would greatly benefit these students. Objective: We used participatory design methodologies with users (young people aged 16-30 years, supportive others, and health professionals) to (1) conduct workshops with users to co-design and culturally adapt the MHeC; (2) inform the development of the MHeC-S alpha prototype; (3) test the usability of the MHeC-S alpha prototype; (4) translate, culturally adapt, and face-validate the MHeC-S self-report assessment; and (5) collect information to inform its beta prototype. Methods: A research and development cycle included several participatory design phases: co-design workshops; knowledge translation; language translation and cultural adaptation; and rapid prototyping and user testing of the MHeC-S alpha prototype. Results: We held 2 co-design workshops with 17 users (10 young people, 7 health professionals). A total of 15 participated in the one-on-one user testing sessions (7 young people, 5 health professionals, 3 supportive others). We collected 225 source documents, and thematic analysis resulted in 5 main themes (help-seeking barriers, technology platform, functionality, content, and user interface). A random sample of 106 source documents analyzed by 2 independent raters revealed almost perfect agreement for functionality (kappa=.86; P\u3c.001) and content (kappa=.92; P\u3c.001) and substantial agreement for the user interface (kappa=.785; P\u3c.001). In this random sample, no annotations were coded for help-seeking barriers or the technology platform. Language was identified as the main barrier to getting medical or psychological services, and smartphones were the most-used device to access the internet. Acceptability was adequate for the prototype’s 5 main elements: home page and triage system, self-report assessment, dashboard of results, booking and video visit system, and personalized well-being plan. The data also revealed gaps in the alpha prototype, such as the need for tailored assessment tools and a greater integration with Spanish-speaking services and communities. Spanish-language apps and e-tools, as well as online mental health information, were lacking. Conclusions: Through a research and development process, we co-designed and culturally adapted, developed and user tested, and evaluated the MHeC-S. By translating and culturally adapting the MHeC to Spanish, we aimed to increase accessibility and availability of e-mental health care in the developing world, and assist vulnerable populations that have migrated to English-speaking countries

    “Sexual” Population Structure and Genetics of the Malaria Agent P. falciparum

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    The population genetics and structure of P. falciparum determine the rate at which malaria evolves in response to interventions such as drugs and vaccines. This has been the source of considerable recent controversy, but here we demonstrate the organism to be essentially sexual, in an area of moderately high transmission in the Lower Shire Valley, Malawi. Seven thousand mosquitoes were collected and dissected, and genetic data were obtained on 190 oocysts from 56 infected midguts. The oocysts were genotyped at three microsatellite loci and the MSP1 locus. Selfing rate was estimated as 50% and there was significant genotypic linkage disequilibrium (LD) in the pooled oocysts. A more appropriate analysis searching for genotypic LD in outcrossed oocysts and/or haplotypic LD in the selfed oocysts found no evidence for LD, indicating that the population was effectively sexual. Inbreeding estimates at MSP1 were higher than at the microsatellites, possibly indicative of immune action against MSP1, but the effect was confounded by the probable presence of null mutations. Mating appeared to occur at random in mosquitoes and evidence regarding whether malaria clones in the same host were related (presumably through simultaneous inoculation in the same mosquito bite) was ambiguous. This is the most detailed genetic analysis yet of P. falciparum sexual stages, and shows P. falciparum to be a sexual organism whose genomes are in linkage equilibrium, which acts to slow the emergence of drug resistance and vaccine insensitivity, extending the likely useful therapeutic lifespan of drugs and vaccines

    Mechanistic Elucidation of the Arylation of Non-Spectator N-Heterocyclic Carbenes at Copper Using a Combined Experimental and Computational Approach

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    CuI(NHC)Br complexes (NHC = N-heterocyclic carbene) undergo a direct reaction with iodobenzene to give 2-arylated benzimidazolium products. The nature of the N-substituent on the NHC ligand influences the reactivity of the CuI(NHC)Br complex toward arylation. N-Benzyl or N-phenyl substituents facilitate arylation, whereas N-mesityl substituents hinder arylation. Density functional theory calculations show that an oxidative addition/reductive elimination pathway involving CuIII species is energetically feasible. A less hindered CuI(NHC)Br complex with N-benzyl groups is susceptible to oxidation reactions to give 1,3-dibenzylbenzimidazolium cations containing a CuIBr anion (various polymorphs). The results described herein are of relevance to C–H functionalization of (benz)azoles
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