11 resultados para Directed Union of Artinian Subrings

em Aston University Research Archive


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Historically, calcitonin gene-related peptide (CGRP) receptors have been divided into two classes, CGRP(1) and CGRP(2).After the cloning of calcitonin receptor-like receptor (CLR) and receptor activity-modifying proteins (RAMPs), it became clear that the CGRP(1) receptor was a complex between CLR and RAMP1. It is now apparent that the CGRP(2) receptor phenotype is the result of CGRP acting at receptors for amylin and adrenomedullin. Accordingly, the term "CGRP(2)" receptor should no longer be used, and the "CGRP(1)" receptor should be known as the "CGRP" receptor.

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The calcitonin family of peptides comprises calcitonin, amylin two calcitonin gene-related peptides (CGRPs), and adrenomedullin. The first calcitonin receptor was cloned in 1991. Its pharmacology is complicated by the existence of several splice variants. The receptors for the other members the family are made up of subunits. The calcitonin-like receptor (CL receptor) requires a single transmembrane domain protein, termed receptor activity modifying protein, RAMP1, to function as a CGRP receptor. RAMP2 and -3 enable the same CL receptor to behave as an adrenomedullin receptor. Although the calcitonin receptor does not require RAMP to bind and respond to calcitonin, it can associate with the RAMPs, resulting in a series of receptors that typically have high affinity for amylin and varied affinity for CGRP. This review aims to reconcile what is observed when the receptors are reconstituted in vitro with the properties they show in native cells and tissues. Experimental conditions must be rigorously controlled because different degrees of protein expression may markedly modify pharmacology in such a complex situation. Recommendations, which follow International Union of Pharmacology guidelines, are made for the nomenclature of these multimeric receptors.

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Primary data obtained from unionized employees in Singapore were used to examine P. A. Bamberger, A. N. Kluger, and R. Suchard's (1999) integrative model of the antecedents and outcomes of union commitment. Structural equation modeling results revealed support for their integrative model. Specifically, the results revealed the influence of job satisfaction on union loyalty to be indirect through organizational commitment. However, the union-related antecedents (union socialization and union instrumentality) were both directly and indirectly related to union loyalty through pro-union attitudes. In addition, union loyalty was related to the individually and organizationally directed union citizenship behavior dimensions. Limitations of the study and implications of the findings are discussed.

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The founding Treaties of the European Union (EU) provide the Commission with bureaucratic structures and functions, and the authority to take a political leadership role in the integration process. However, the legitimacy of the Commission's authority to act either as a bureaucracy or as a political institution is periodically contested, as is the authority and leadership of its President. Max Weber's theory of the legitimation of authority suggests itself in this context as a working tool for assessing the nature of institutional and individual authority and leadership in the Commission and the broader EU context. Weber's typology of authority offers both an understanding of the changes in the Commission's fortunes within the 'would-be polity' of the European institutions, and an appraisal of claims to authority at the individual level by the Commission President. When applied to two contrasting moments in the Commission's life during the presidency of Jacques Delors (the generating of the White Papers of 1985 and 1993), Weber's typology provides an explanation for the evolution of the legitimation of these forms of authority in terms of, first, the Union's imperfect provisions for legitimate claims to leadership authority on 'charismatic' grounds and, second, the absence in the Union of resources for leadership legitimacy based on 'traditional'-type authority, such as explicit, popular, or party political European-wide support for the project of European union. These are resources which, if present in the EU, would legitimise calls to reform the EU's institutions in the direction of more integration and a more federal polity. The case studies offer an appraisal of the functioning and malfunctioning of authority within the Union, as well as a critical assessment of the applicability of the Weberian model to the legitimation of authority in the EU.

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The delicately orchestrated process of bone fracture healing is not always successful and long term non union of fractured bone occurs in 5-20% of all cases. Atrophic fracture non unions have been described as the most difficult to treat and this is thought to arise through a cellular and local failure of osteogenesis. However, little is known about the presence and osteogenic proficiency of cells in the local area of non union tissue. We have examined the growth and differentiation potential of cells isolated from human non union tissues compared with normal human bone marrow mesenchymal stromal cells (BMSC). We report the isolation and culture expansion of a population of non union stromal cells (NUSC) which have a CD profile similar to that of BMSC, i.e. CD34-ve, CD45-ve and CD105+ve. The NUSC demonstrated multipotentiality and differentiated to some extent along chondrogenic, adipogenic and osteogenic lineages. However, and importantly, the NUSC showed significantly reduced osteogenic differentiation and mineralization in vitro compared to BMSC. We also found increased levels of cell senescence in NUSC compared to BMSC based on culture growth kinetics and cell positivity for senescence associated beta galactosidase (SA-beta-Gal) activity. The reduced capacity of NUSC to form osteoblasts was associated with significantly elevated secretion of Dickkopf-1 (Dkk-1) which is an important inhibitor of Wnt signalling during osteogenesis, compared to BMSC. Conversely, treating BMSC with levels of rhDkk-1 that were equivalent to those levels secreted by NUSC inhibited the capacity of BMSC to undergo osteogenesis. Treating BMSC with NUSC conditioned medium also inhibited the capacity of the BMSC to undergo osteogenic differentiation when compared to their treatment with BMSC conditioned medium. Our results suggest that the development of fracture non union is linked with a localised reduced capacity of cells to undergo osteogenesis, which in turn is associated with increased cell senescence and Dkk-1 secretion.

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The numbers of zoospores produced by a pathogenic strain of Saprolegnia diclina and their behaviour are markedly influenced by a variety of environmental variables including temperature, pH, oxygen tension and the presence of biocides. The use of the latter is not recommended, as fish readily succumb to equivalent concentrations of biocides. Analysis of the pattern of distribution of resulting zoospore cysts demonstrates that zoospores become dispersed by random movement even while in the proximity of the parent colony’s nutrient source. However, the presence of amino acids, in particular aspartic and glutamic acid, at concentrations which occur in fish tissue promotes the directed movement of zoospores towards the nutrient source thereby encouraging the colonization of fresh sites.

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In fibrotic conditions increases in TG2 activity has been linked to an increase in the deposition of extracellular matrix proteins. Using TG2 transfected Swiss 3T3 fibroblasts expressing TG2 under the control of the tetracycline-regulated inducible promoter, we demonstrate that induction of TG2 not only stimulates an increase in collagen and fibronectin deposition but also an increase in the expression of these proteins. Increased TG2 expression in these fibroblasts led to NF-kappaB activation, resulting in the increased expression of transforming growth factor (TGF) beta(1). In addition, cells overexpressing TG2 demonstrated an increase in biologically active TGFbeta(1) in the extracellular environment. A specific site-directed inhibitor of TG abolished the NF-kappaB and TGFbeta1 activation and the subsequent elevation in the synthesis and deposition of extracellular matrix proteins, confirming that this process depends on the induction of transglutaminase activity. Treatment of TG2-induced fibroblasts with nontoxic doses of nitric oxide donor S-nitroso-N-acetylpenicillamine resulted in decreased TG2 activity and apprehension of the inactive enzyme on the cell surface. This was paralleled by a reduction in activation of NF-kappaB and TGFbeta(1) production with a subsequent decrease in collagen expression and deposition. These findings support a role for NO in the regulation of TG2 function in the extracellular environment.

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Diabetic nephropathy affects 30-40% of diabetics leading to end-stage kidney failure through progressive scarring and fibrosis. Previous evidence suggests that tissue transglutaminase (tTg) and its protein cross-link product epsilon(gamma-glutamyl)lysine contribute to the expanding renal tubulointerstitial and glomerular basement membranes in this disease. Using an in vitro cell culture model of renal proximal tubular epithelial cells we determined the link between elevated glucose levels with changes in expression and activity of tTg and then, by using a highly specific site directed inhibitor of tTg (1,3-dimethyl-2[(oxopropyl)thio]imidazolium), determined the contribution of tTg to glucose-induced matrix accumulation. Exposure of cells to 36 mm glucose over 96 h caused an mRNA-dependent increase in tTg activity with a 25% increase in extracellular matrix (ECM)-associated tTg and a 150% increase in ECM epsilon(gamma-glutamyl)lysine cross-linking. This was paralleled by an elevation in total deposited ECM resulting from higher levels of deposited collagen and fibronectin. These were associated with raised mRNA for collagens III, IV, and fibronectin. The specific site-directed inhibitor of tTg normalized both tTg activity and ECM-associated epsilon(gamma-glutamyl)lysine. Levels of ECM per cell returned to near control levels with non-transcriptional reductions in deposited collagen and fibronectin. No changes in transforming growth factor beta1 (expression or biological activity) occurred that could account for our observations, whereas incubation of tTg with collagen III indicated that cross-linking could directly increase the rate of collagen fibril/gel formation. We conclude that Tg inhibition reduces glucose-induced deposition of ECM proteins independently of changes in ECM and transforming growth factor beta1 synthesis thus opening up its possible application in the treatment other fibrotic and scarring diseases where tTg has been implicated.

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This thesis describes the development of a complete data visualisation system for large tabular databases, such as those commonly found in a business environment. A state-of-the-art 'cyberspace cell' data visualisation technique was investigated and a powerful visualisation system using it was implemented. Although allowing databases to be explored and conclusions drawn, it had several drawbacks, the majority of which were due to the three-dimensional nature of the visualisation. A novel two-dimensional generic visualisation system, known as MADEN, was then developed and implemented, based upon a 2-D matrix of 'density plots'. MADEN allows an entire high-dimensional database to be visualised in one window, while permitting close analysis in 'enlargement' windows. Selections of records can be made and examined, and dependencies between fields can be investigated in detail. MADEN was used as a tool for investigating and assessing many data processing algorithms, firstly data-reducing (clustering) methods, then dimensionality-reducing techniques. These included a new 'directed' form of principal components analysis, several novel applications of artificial neural networks, and discriminant analysis techniques which illustrated how groups within a database can be separated. To illustrate the power of the system, MADEN was used to explore customer databases from two financial institutions, resulting in a number of discoveries which would be of interest to a marketing manager. Finally, the database of results from the 1992 UK Research Assessment Exercise was analysed. Using MADEN allowed both universities and disciplines to be graphically compared, and supplied some startling revelations, including empirical evidence of the 'Oxbridge factor'.

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This book analyses the Christian Democratic Union of Germany (CDU), one of Europe’s most successful and influential political parties. The CDU might have been expected to struggle in the circumstances of a more diverse, secular reunified Germany, yet it has prospered to an extent almost unparalleled in western Europe. Chapters consider the CDU’s policies (the factors driving them, their variation across Germany, the relationship to women, and the welfare state), its organisational development and change, and its position within the party system. Contributors particularly emphasise the diversity of the CDU, and the way it varies across Germany’s regions. The CDU is compared to other Christian Democratic parties, and special consideration is given to the CDU’s Bavarian sister party, the Christian Social Union (CSU). This book was published as a special issue of German Politics.

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The IUPHAR database (IUPHAR-DB) integrates peer-reviewed pharmacological, chemical, genetic, functional and anatomical information on the 354 nonsensory G protein-coupled receptors (GPCRs), 71 ligand-gated ion channel subunits and 141 voltage-gated-like ion channel subunits encoded by the human, rat and mouse genomes. These genes represent the targets of approximately one-third of currently approved drugs and are a major focus of drug discovery and development programs in the pharmaceutical industry. IUPHAR-DB provides a comprehensive description of the genes and their functions, with information on protein structure and interactions, ligands, expression patterns, signaling mechanisms, functional assays and biologically important receptor variants (e.g. single nucleotide polymorphisms and splice variants). In addition, the phenotypes resulting from altered gene expression (e.g. in genetically altered animals or in human genetic disorders) are described. The content of the database is peer reviewed by members of the International Union of Basic and Clinical Pharmacology Committee on Receptor Nomenclature and Drug Classification (NC-IUPHAR); the data are provided through manual curation of the primary literature by a network of over 60 subcommittees of NC-IUPHAR. Links to other bioinformatics resources, such as NCBI, Uniprot, HGNC and the rat and mouse genome databases are provided. IUPHAR-DB is freely available at http://www.iuphar-db.org. © 2008 The Author(s).