4 resultados para Leonidas, I, King of Sparta, d. 480 B.C.
em Aston University Research Archive
Resumo:
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Resumo:
During inflammation, many cell types release reactive oxygen species (ROS) via the respiratory burst. These ROS are potent oxidants of LDL and its major protein, apolipoprotein B. Whilst native LDL is taken up by endothelial cells via a feedback controlled receptor-regulated process, oxidative modification of LDL renders it a ligand for many scavenger receptors. Scavenger receptors include CD-36, LOX-1 and the prototypic macrophage SR A I/II, all of which are variably expressed. Uncontrolled uptake of oxidised LDL is implicated in the pathogenesis of atherosclerosis. In addition, oxidised LDL increases CCR2 protein and mRNA expression on monocytes, and thus may contribute to monocyte retention and perpetuation in inflammatory, unstable atherosclerotic lesions. However, little data are available on the effects of specific minor modifications to apolipoprotein B. In order to identify the sequence specificity and nature of oxidative modifications which confer altered properties on LDL, we have investigated the effects of modified peptides (which correspond to the putative LDLR binding domain) on LDL uptake by HUVECs and U937 monocytes.
Resumo:
This paper extends previous analyses of the choice between internal and external R&D to consider the costs of internal R&D. The Heckman two-stage estimator is used to estimate the determinants of internal R&D unit cost (i.e. cost per product innovation) allowing for sample selection effects. Theory indicates that R&D unit cost will be influenced by scale issues and by the technological opportunities faced by the firm. Transaction costs encountered in research activities are allowed for and, in addition, consideration is given to issues of market structure which influence the choice of R&D mode without affecting the unit cost of internal or external R&D. The model is tested on data from a sample of over 500 UK manufacturing plants which have engaged in product innovation. The key determinants of R&D mode are the scale of plant and R&D input, and market structure conditions. In terms of the R&D cost equation, scale factors are again important and have a non-linear relationship with R&D unit cost. Specificities in physical and human capital also affect unit cost, but have no clear impact on the choice of R&D mode. There is no evidence of technological opportunity affecting either R&D cost or the internal/external decision.
Resumo:
A new family of multifunctional scaffolds, incorporating selected biopolymer coatings on basic Bioglass® derived foams has been developed. The polymer coatings were investigated as carrier of vancomycin which is a suitable drug to impart antibiotic function to the scaffolds. It has been proved that coating with PLGA (poly(lactic-co-glycolic acid)) with dispersed vancomycin-loaded microgels provides a rapid delivery of drug to give antibacterial effects at the wound site and a further sustained release to aid mid to long-term healing. Furthermore, the microgels also improved the bioactivity of the scaffolds by acting as nucleation sites for the formation of HA crystals in simulated body fluid. © 2013 Elsevier B.V. All rights reserved.