72 resultados para Homology and differentiation relationships
Resumo:
Introduction: Chitons (Polyplacophora) are molluscs considered to have a simple nervous system without cephalisation. The position of the class within Mollusca is the topic of extensive debate and neuroanatomical characters can provide new sources of phylogenetic data as well as insights into the fundamental biology of the organisms. We report a new discrete anterior sensory structure in chitons, occurring throughout Lepidopleurida, the order of living chitons that retains plesiomorphic characteristics.
Results: The novel "Schwabe organ" is clearly visible on living animals as a pair of streaks of brown or purplish pigment on the roof of the pallial cavity, lateral to or partly covered by the mouth lappets. We describe the histology and ultrastructure of the anterior nervous system, including the Schwabe organ, in two lepidopleuran chitons using light and electron microscopy. The oesophageal nerve ring is greatly enlarged and displays ganglionic structure, with the neuropil surrounded by neural somata. The Schwabe organ is innervated by the lateral nerve cord, and dense bundles of nerve fibres running through the Schwabe organ epithelium are frequently surrounded by the pigment granules which characterise the organ. Basal cells projecting to the epithelial surface and cells bearing a large number of ciliary structures may be indicative of sensory function. The Schwabe organ is present in all genera within Lepidopleurida (and absent throughout Chitonida) and represents a novel anatomical synapomorphy of the clade.
Conclusions: The Schwabe organ is a pigmented sensory organ, found on the ventral surface of deep-sea and shallow water chitons; although its anatomy is well understood, its function remains unknown. The anterior commissure of the chiton oesophagial nerve ring can be considered a brain. Our thorough review of the chiton central nervous system, and particularly the sensory organs of the pallial cavity, provides a context to interpret neuroanatomical homology and assess this new sense organ.
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Graphene, due to its outstanding properties, has become the topic of much research activity in recent years. Much of that work has been on a laboratory scale however, if we are to introduce graphene into real product applications it is necessary to examine how the material behaves under industrial processing conditions. In this paper the melt processing of polyamide 6/graphene nanoplatelet composites via twin screw extrusion is investigated and structure–property relationships are examined for mechanical and electrical properties. Graphene nanoplatelets (GNPs) with two aspect ratios (700 and 1000) were used in order to examine the influence of particle dimensions on composite properties. It was found that the introduction of GNPs had a nucleating effect on polyamide 6 (PA6) crystallization and substantially increased crystallinity by up to 120% for a 20% loading in PA6. A small increase in crystallinity was observed when extruder screw speed increased from 50 rpm to 200 rpm which could be attributed to better dispersion and more nucleation sites for crystallization. A maximum enhancement of 412% in Young's modulus was achieved at 20 wt% loading of GNPs. This is the highest reported enhancement in modulus achieved to date for a melt mixed thermoplastic/GNPs composite. A further result of importance here is that the modulus continued to increase as the loading of GNPs increased even at 20 wt% loading and results are in excellent agreement with theoretical predictions for modulus enhancement. Electrical percolation was achieved between 10–15 wt% loading for both aspect ratios of GNPs with an increase in conductivity of approximately 6 orders of magnitude compared to the unfilled PA6.
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Over the last two decades there has been ongoing debate about the impact of environmental practices on operational performance. In recent years, studies have started to move beyond assessing the direct impact of environmental management on different dimensions of performance to consider factors that might moderate or mediate this relationship. This study considers the extent to which environmental integration and environmental capabilities moderate the relationship between pollution prevention and environmental performance outcomes. The mediating influence of environmental performance on the relationship between pollution prevention and cost and flexibility performance is also considered. Data were collected from a sample of UK food manufacturers and analysed using multiple regression analysis. The findings indicate the existence of some moderated and mediated relationships suggesting that there is more to improving performance than implementing environmental practices.
Beyond Pietism and Prosperity: Religious Resources for Reconstruction and Reconciliation in Zimbabwe
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It is often assumed that charismatic Christianity in Africa promotes either a pietist withdrawal from social and political concerns, or a preoccupation with gaining individual health and wealth (the prosperity gospel). This research presents an alternative vision of the role of charismatic Christianity in Zimbabwe. Drawing on an ethnographic case study of a charismatic congregation, it analyzes how these Christians are drawing links between spirituality and social action. This congregation is developing an egalitarian conception of power, promoting service to the poor, and using biblical discourses to support their actions. This can be understood as part of a wider process in which Zimbabwean Christians are using religious resources to develop a vision for reconstruction and reconciliation. This article points to further areas in which the churches could use their public position to raise sensitive issues, including how to deal with the past and heal relationships between previously antagonistic groups.
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Nontypeable Haemophilus influenzae (NTHI) is an opportunistic pathogen that is an important cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). COPD is an inflammatory disease of the airways, and exacerbations are acute inflammatory events superimposed on this background of chronic inflammation. Azithromycin (AZM) is a macrolide antibiotic with antibacterial and anti-inflammatory properties and a clinically proven potential for AECOPD prevention and management. Relationships between AZM efficacy and resistance by NTHI and between bactericidal and immunomodulatory effects on NTHI respiratory infection have not been addressed. In this study, we employed two pathogenic NTHI strains with different AZM susceptibilities (NTHI 375 [AZM susceptible] and NTHI 353 [AZM resistant]) to evaluate the prophylactic and therapeutic effects of AZM on the NTHI-host interplay. At the cellular level, AZM was bactericidal toward intracellular NTHI inside alveolar and bronchial epithelia and alveolar macrophages, and it enhanced NTHI phagocytosis by the latter cell type. These effects correlated with the strain MIC of AZM and the antibiotic dose. Additionally, the effect of AZM on NTHI infection was assessed in a mouse model of pulmonary infection. AZM showed both preventive and therapeutic efficacies by lowering NTHI 375 bacterial counts in lungs and bronchoalveolar lavage fluid (BALF) and by reducing histopathological inflammatory lesions in the upper and lower airways of mice. Conversely, AZM did not reduce bacterial loads in animals infected with NTHI 353, in which case a milder anti-inflammatory effect was also observed. Together, the results of this work link the bactericidal and anti-inflammatory effects of AZM and frame the efficacy of this antibiotic against NTHI respiratory infection.
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The ongoing, potentially worsening problem of sexual violence and harassment on university campuses has emerged in the last few years as an area of concern. Female students have been identified as one of the most likely groups to experience sexual violence and this violence is exacerbated by contemporary student cultures around alcohol consumption and gendered and sexual norms. University campuses have also become central to prevention efforts in many countries due to their relatively accessible populations and an ability to implement social policies at an institutional level.
Many of these measures are based around promoting or educating students about sexual consent, and particularly notions of affirmative consent, expressed as ‘Yes means Yes’. However, there exists little research around sexual ethics with students exploring whether consent is in fact the best way to tackle cultural problems of sexual violence on campus. This paper makes use of existing literature on sexual ethics and focus group research undertaken with Australian university students to argue for an approach to the problem of sexual ethics on campus that is broader than simply focusing on training programs in sexual consent. It identifies a number of limitations to the consent framework and argues that prevention efforts need to more seriously engage with broader cultural norms around heterosexuality and gendered relationships.
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Innate immunity represents the first line of defence against invading pathogens. It consists of an initial inflammatory response that recruits white blood cells to the site of infection in an effort to destroy and eliminate the pathogen. Some pathogens replicate within host cells, and cell death by apoptosis is an important effector mechanism to remove the replication niche for such microbes. However, some microbes have evolved evasive strategies to block apoptosis, and in these cases host cells may employ further countermeasures, including an inflammatory form of cell death know as necroptosis. This review aims to highlight the importance of the RIP kinase family in controlling these various defence strategies. RIP1 is initially discussed as a key component of death receptor signalling and in the context of dictating whether a cell triggers a pathway of pro-inflammatory gene expression or cell death by apoptosis. The molecular and functional interplay of RIP1 and RIP3 is described, especially with respect to mediating necroptosis and as key mediators of inflammation. The function of RIP2, with particular emphasis on its role in NOD signalling, is also explored. Special attention is given to emphasizing the physiological and pathophysiological contexts for these various functions of RIP kinases.
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Molecular Medicine and Molecular Pathology are integral parts of Haematology as we enter the new millennium. Their origins can be linked to fundamental developments in the basic sciences, particularly genetics, chemistry and biochemistry. The structure of DNA and the genetic code that it encrypts are the critical starting points to our understanding of these new disciplines. The genetic alphabet is a simple one, consisting of just 4 letters, buts its influence is crucial to human development and differentiation. The concept of a gene is not a new one but the Human Genome Project (a joint world-wide effort to characterise our entire genetic make-up) is providing an invaluable understanding of how genes function in normal cellular processes and pinpointing how disruption of these processes can lead to disease. Transcription and translation are the key events by which our genotype is converted to our phenotype (via a messenger RNA intermediate), producing the myriad proteins and enzymes which populate the cellular factory of our body. Unlike the bacterial or prokaryotic genome, the human genome contains a large amount of non coding DNA (less than 1% of our genome codes for proteins), and our genes are interrupted, with the coding regions or exons separated by non coding introns. Precise removal of the intronic material after transcription (though a process called splicing) is critical for efficient translation to occur. Incorrect splicing can lead to the generation of mutant proteins, which can have a dilaterious effect on the phenotype of the individual. Thus the 100,000-200,000 genes which are present in each cell in our body have a defined control mechanism permitting efficient and appropriate expression of proteins and enzymes and yet a single base change in just one of those genes can lead to diseases such as haemophilia or fanconis anaemia.
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This paper examines the prospects for sustainable rural tourism within a rural development paradigm. Specifically, an adaptive management approach is proposed as a means of understanding and accommodating the different goals and interests that exist within multi-functional rural areas. This model allows priorities to change in line with particular situations while remaining sensitive to economic, environmental, social and cultural impacts. The proposed Mourne National Park in Northern Ireland, also designated an Area of Outstanding Natural Beauty (AONB), forms the backdrop for this study. Through a critique of a consultation process that was undertaken with the community the question is posed: can a sustainable rural tourism approach achieve meaningful community engagement and thereby reflect the needs of the community? Central to the analysis are the power differentials between the various partners participating in this model of governance. The conclusions consider implications for rural communities, revealing how trusting and meaningful relationships are central to facilitating collaboration, cooperation and adaptation.
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Early contractor involvement is a topic that has attracted attention from construction practitioners and researchers in the UK since the 1990s. It has been adopted to introduce construction knowledge and experience to the design process, and to integrate design with construction. In contrast with the limited number of previous studies on early contractor involvement, which used case studies, a questionnaire survey was conducted in this study, to investigate the application of early contractor involvement in current practice and its impact on project performance in terms of time, cost and quality. From an analysis of the questionnaire results, early contractor involvement is found to be increasingly used in the construction industry, and to have a significant impact on cost and time performance. This research provides empirical evidence related to the practice of early contractor involvement. It demonstrates the major influence of early contractor involvement on management processes and working relationships during a project, which contribute to performance improvement and project success.
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In 1974, pursuing his interest in the infra-ordinary – ‘the banal, the quotidian, the obvious, the common, the ordinary, the back-ground noise, the habitual’ – Georges Perec wrote about an idea for a novel:
‘I imagine a Parisian apartment building whose façade has been removed … so that all the rooms in the front, from the ground floor up to the attics, are instantly and simultaneously visible’.
In Life A User’s Manual (1978) the consummation of this precis, patterns of existence are measured within architectural space with an archaeological sensibility that sifts through narrative and décor, structure and history, services and emotion, the personal and the system, ascribing commensurate value to each.
Apartment comes from the Italian appartare meaning ‘to separate’. The space of the boundary between activities is reduced to a series of intimately thin lines: the depth of a floor, a party wall, a window, the convex peep-hole in a door, or the façade that Perec seeks to render invisible. The apartness of the apartment is accelerated when aligned with short-term tenancies. Here Perec’s interweaving of personal histories over time using the structure of the block, gives way to convivialities of detachment: inhabitants are temporary, their personalities anonymous, their activities unknown or overlooked.
Borrowing methods from Perec, to move somewhere between conjecture, analysis and other documentation and tracing relationships between form, structure, materiality, technology, organisation, tenure and narrative use, this paper interrogates the late twentieth-century speculative apartment block in Britain and Ireland arguing that its speculative and commodified purpose allows a series of lives that are often less than ordinary to inhabit its spaces.
Henri Lefebvre described the emergence of an ‘abstract space’ under capitalism in terms which can be applied to the apartment building: the division of space into freely alienable privatised parcels which can be exchanged. Vertical distributions of class and other new, contiguous social and spatial relationships are couched within a paradox: the building which allows such proximities is also a conductor of division. Apartment comes from the Italian appartare meaning ‘to separate’. The space of the boundary between activities is reduced to a series of intimately thin lines: the depth of a floor, a party wall, a window, the convex peep-hole in a door, or the façade that Perec seeks to render invisible. The apartness of the apartment is accelerated when aligned with short-term tenancies. Here Perec’s interweaving of personal histories over time using the structure of the block, gives way to convivialities of detachment: inhabitants are temporary, their personalities anonymous, their activities unknown or overlooked.
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Human induced pluripotent stem (iPS) cell-derived endothelial cells (ECs) hold clear potential for therapeutic angiogenesis as a novel strategy for ischaemic disease. Recently, we have developed a novel method for direct reprogramming of partial iPS (PiPS) cells, which unlike iPS cells, are generated before pluripotency so do not form tumours, and may be differentiated into ECs with characteristic morphology and pro-angiogenic actions. Our previous work showed that PiPS-derived ECs are capable of forming vascular-like tubes both in vitro and in vivo and promoting re-endothelialisation of ischemic tissue, with greater effectiveness versus mature ECs.
Interestingly, our preliminary data demonstrate that Nox NADPH oxidases, which are reported to influence stem cell function, are progressively induced during PiPs/PiPS-EC differentiation and in response to hypoxia, with Nox4 demonstrating highest expression. As this isoform is an established regulator of angiogenesis, we hypothesize that Nox4 plays a key role in modulating PiPS-EC generation and angiogenic function.
The aim of this project is therefore to investigate: (1) the specific role of Nox4 in direct reprogramming of PiPS cells and differentiation to PiPS-ECs; (2) whether genetic manipulation of Nox4 influences in vitro function of PiPs-ECs and their ability to promote in vivo angiogenesis. This will be achieved by employing established in vitro functional assays and an experimental model of hindlimb ischaemia with assessment of relevant end-points. Identification of a key role for Nox4 in regulating PiPS-EC generation/function may inform selective targeting of this isoform to enhance the efficiency of PiPS-EC differentiation and their capacity to treat ischemic disease.