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Experimental Background (experimental + background)
Selected AbstractsA constitutive model for the dynamic and high-pressure behaviour of a propellant-like material: Part I: Experimental background and general structure of the modelINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2001Hervé Trumel Abstract This paper is the first part of a work that aims at developing a mechanical model for the behaviour of propellant-like materials under high confining pressure and strain rate. The behaviour of a typical material is investigated experimentally. Several microstructural deformation processes are identified and correlated with loading conditions. The resulting behaviour is complex, non-linear, and characterized by multiple couplings. The general structure of a relevant model is sought using a thermodynamic framework. A viscoelastic-viscoplastic-compaction model structure is derived under suitable simplifying assumptions, in the framework of finite, though moderate, strains. Model development, identification and numerical applications are given in the companion paper. Copyright © 2001 John Wiley & Sons, Ltd. [source] Why the Open Method of Coordination Is Bad For You: A Letter to the EUEUROPEAN LAW JOURNAL, Issue 3 2007Vassilis Hatzopoulos Most writers explore the tentative outcomes of the method, since they lack a solid experimental background, against which to assess its actual effectiveness. Lately, however, some empirical studies have come to light. Among them, some fully discredit the OMC as a means of pursuing common policies at the EU level; while others recognise indirect effects, essentially at the national level of policy setting. On the basis of this assumption, i.e. that the OMC has only restricted direct effects in the short term and indirect effects in the medium to long term, the present article first puts forward a series of arguments against the current ,spread' of the OMC, and then offers some proposals on how to neutralise some of the identified shortfalls of the OMC. Despite the title of the article, the final conclusion is not for the demise of the OMC, but rather for its ,communautarisation'. It is put forward that both the application and the effects of the OMC should be more clearly defined and better integrated with the other pre-existing forms of cooperation, in accordance with basic requirements stemming from the Community legal order. [source] Experimental problems in the application of UV/visible based methods as the quantification tool for the entrapped/released insulin from PLGA carriersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2009V.L. Lassalle Abstract BACKGROUND: Controlled release of medicaments from biodegradable polymers remains the most convenient way for their sustained release. Although a number of articles have been published, experimental work involving the preparation of polymer-based carriers and release procedures are not described with sufficient level of detail to allow other researchers to reproduce the experiments and to compare published results with their own. In this contribution the experimental background of the entrapment and release of insulin from PLGA carriers is described and the problems found at each step related to UV/Visible method used to quantify them are addressed in detail. RESULTS: The quantification of entrapped insulin by UV/visible methods was affected by aggregation. The design of the release experiment influenced the results regarding the entrapment efficiency (EE) and the maximum percentage of released insulin. It was also found that the presence of colloidal polymeric particles, insufficient centrifugation times and the kind of solvent used in the release test might lead to mistakes in the percentage of liberated insulin when UV/visible based methods are employed. CONCLUSIONS: This contribution demonstrates that serious discrepancies in the EE and percentage of released protein may arise if some key experimental factors are not taken into account. Therefore, the analysis presented here tries to point out important aspects of this topic currently not reported, unnoticed or not properly analyzed in the open literature. The results are useful for the entrapment of any protein on any polymeric device using UV/visible based methods to quantify them. Copyright © 2009 Society of Chemical Industry [source] Muscle preservation using an implantable electrical system after nerve injury and repairMICROSURGERY, Issue 6 2001F.R.C.S.(C), Stephen C. Nicolaidis M.D. The value of continuous electrical stimulation of denervated muscles after nerve injury and repair has been clearly shown in a series of laboratory experiments in three animal models. This experimental background, which showed improved muscle preservation and better functional results, evolved into a clinical study that included 15 patients with peripheral nerve injuries in the upper extremities, 3 patients with brachial plexus injuries, and three patients with facial nerve paralysis. Improved functional results were obtained using this implantable system, which were similar to those achieved with the animal experiments. All patients had muscle stimulation for extended periods ranging from 127 to 346 days. Analysis of the results showed satisfactory nerve regeneration on clinical examination and with electromyographic studies. Functional muscle analysis varied somewhat from patient to patient, but every patient had a satisfactory to excellent recovery. The results from this study have clearly shown the benefits of continuous muscle stimulation using an implantable electrical system after nerve injury and repair expansion of the project to a larger patient cohort is indicated. © 2001 Wiley-Liss, Inc. MICROSURGERY 21:241,247 2001 [source] Selective apoptosis of natural killer-cell tumours by l -asparaginaseBRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2005Miki Ando Summary We examined the effectiveness of various anti-tumour agents to natural killer (NK)-cell tumour cell lines and samples, which are generally resistant to chemotherapy, using flow cytometric terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labelling (TUNEL) assay. Although NK-YS and NK-92 were highly resistant to various anti-tumour agents, l -asparaginase induced apoptosis in these two NK-cell lines. NK-cell leukaemia/lymphoma and acute lymphoblastic leukaemia (ALL) samples were selectively sensitive to l -asparaginase and to doxorubicin (DXR) respectively. Samples of chronic NK lymphocytosis, an NK-cell disorder with an indolent clinical course, were resistant to both drugs. Our study clearly separated two major categories of NK-cell disorders and ALL according to the sensitivity to DXR and l -asparaginase. We examined asparagine synthetase levels by real-time quantitative polymerase chain reaction (RQ-PCR) and immunostaining in these samples. At least in nasal-type NK-cell lymphoma, there was a good correlation among asparagine synthetase expression, in vitro sensitivity and clinical response to l -asparaginase. In aggressive NK-cell leukaemia, although asparagine synthetase expression was high at both mRNA and protein levels, l -asparaginase induced considerable apoptosis. Furthermore, samples of each disease entity occupied a distinct area in two-dimensional plotting with asparagine synthetase mRNA level (RQ-PCR) and in vitrol -asparaginase sensitivity (TUNEL assay). We confirmed rather specific anti-tumour activity of l -asparaginase against NK-cell tumours in vitro, which provides an experimental background to the clinical use of l -asparaginase for NK-cell tumours. [source] Tumour necrosis factor-alpha (TNF- ,) enhances lymphocyte migration into rheumatoid synovial tissue transplanted into severe combined immunodeficient (SCID) miceCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2000S. Wahid Adhesion mechanisms play a major role in the recruitment of peripheral blood lymphocytes (PBL) which characteristically infiltrate rheumatoid arthritis (RA) synovium and other chronically inflamed tissues. Through a sequential series of complex integrated adhesion and signalling events, ,multistep model of migration', specific subsets of PBL are recruited into inflamed tissues. In this process both leucocyte receptors and microvascular endothelial (MVE) counter-receptors play a critical role. The MVE in particular, during an inflammatory state, is the target of various inflammatory mediators that cause the up-regulation of several cell adhesion molecules (CAM). One of the most important factors known to be a powerful inducer of MVE CAM is TNF- ,. Conversely, blocking TNF- , causes a down-modulation of CAM expression. To test directly the capacity of TNF- , to induce cell migration into RA synovium we adapted a model in which synovial grafts were implanted into SCID mice subcutaneously. Using this model we demonstrate that: (i) transplants remain viable and become vascularized and fed by mouse subdermal vessels; (ii) the mouse vasculature connects to the transplant vasculature which maintains the ability to express human CAM; (iii) intragraft injections of TNF- , up-regulate the expression of human CAM, following the down-regulation which occurred 4 weeks post-transplantation; and (iv) the up-regulation of graft CAM is associated with increased human PBL migration into the transplants. This study provides direct evidence in vivo of the capacity of TNF- , to induce cell migration. In addition, it provides the experimental background for the optimal use of this model. [source] | ||||||||||