The role of the innate immune system in the clearance of apoptotic cells

Rapid clearance of dying cells is a vital feature of apoptosis throughout development, tissue homeostasis and resolution of inflammation. The phagocytic removal of apoptotic cells is mediated by both professional and amateur phagocytes, armed with a series of pattern recognition receptors that participate in host defence and apoptotic cell clearance. CD14 is one such molecule. It is involved in apoptotic cell clearance (known to be immunosuppressive and anti-inflammatory) and binding of the pathogen-associated molecular pattern, lipopolysaccharides (a pro-inflammatory event). Thus CD14 is involved in the assembly of two distinct ligand-dependent macrophage responses. This project sought to characterise the involvement of the innate immune system, particularly CD14, in the removal of apoptotic cells. The role of non-myeloid CD14 was also considered and the data suggests that the expression of CD14 by phagocytes may define their professional status as phagocytes. To assess if differential CD14 ligation causes the ligand-dependent divergence in macrophage responses, a series of CD14 point mutants were used to map the binding of apoptotic cells and lipopolysaccharides. Monoclonal antibodies, 61D3 and MEM18, known to interfere with ligand-binding and responses, were also mapped. Data suggests that residue 11 of CD14, is key for the binding of 61D3 (but not MEM18), LPS and apoptotic cells, indicating lipopolysaccharides and apoptotic cells bind to similar residues. Furthermore using an NF-kB reporter, results show lipopolysaccharides but not apoptotic cells stimulate NF-kB. Taken together these data suggests ligand-dependent CD14 responses occur via a mechanism that occurs downstream of CD14 ligation but upstream of NF-?B activation. Alternatively apoptotic cell ligation of CD14 may not result in any signalling event, possibly by exclusion of TLR-4, suggesting that engulfment receptors, (e.g. TIM-4, BAI1 and Stablin-2) are required to mediate the uptake of apoptotic cells and the associated anti-inflammatory response.

Measuring performance of virtual learning environment system in higher education

Purpose – The purpose of this paper is to measure the performance of commercial virtual learning environment (VLE) systems, which helps the decision makers to select the appropriate system for their institutions. Design/methodology/approach – This paper develops an integrated multiple criteria decision making approach, which combines the analytic hierarchy process (AHP) and quality function deployment (QFD), to evaluate and select the best system. The evaluating criteria are derived from the requirements of those who use the system. A case study is provided to demonstrate how the integrated approach works. Findings – The major advantage of the integrated approach is that the evaluating criteria are of interest to the stakeholders. This ensures that the selected system will achieve the requirements and satisfy the stakeholders most. Another advantage is that the approach can guarantee the benchmarking to be consistent and reliable. From the case study, it is proved that the performance of a VLE system being used at the university is the best. Therefore, the university should continue to run the system in order to support and facilitate both teaching and learning. Originality/value – It is believed that there is no study that measures the performance of VLE systems, and thus decision makers may have difficulties in system evaluation and selection for their institutions.

NF-κB mediates proteolysis-inducing factor induced protein degradation and expression of the ubiquitin-proteasome system in skeletal muscle

Loss of skeletal muscle in cancer cachexia has a negative effect on both morbidity and mortality. The role of nuclear factor-κB (NF-κB) in regulating muscle protein degradation and expression of the ubiquitin-proteasome proteolytic pathway in response to a tumour cachectic factor, proteolysis-inducing factor (PIF), has been studied by creating stable, transdominant-negative, muscle cell lines. Murine C2C12 myoblasts were transfected with plasmids with a CMV promoter that had mutations at the serine phosphorylation sites required for degradation of I-κBα, an NF-κB inhibitory protein, and allowed to differentiate into myotubes. Proteolysis-inducing factor induced degradation of I-κBα, nuclear accumulation of NF-κB and an increase in luciferase reporter gene activity in myotubes containing wild-type, but not mutant, I-κBα, proteins. Proteolysis-inducing factor also induced total protein degradation and loss of the myofibrillar protein myosin in myotubes containing wild-type, but not mutant, plasmids at the same concentrations as those causing activation of NF-κB. Proteolysis-inducing factor also induced increased expression of the ubiquitin-proteasome pathway, as determined by 'chymotrypsin-like' enzyme activity, the predominant proteolytic activity of the β-subunits of the proteasome, protein expression of 20S α-subunits and the 19S subunits MSSI and p42, as well as the ubiquitin conjugating enzyme, E214k, in cells containing wild-type, but not mutant, I-κBα. The ability of mutant I-κBα to inhibit PIF-induced protein degradation, as well as expression of the ubiquitin-proteasome pathway, confirms that both of these responses depend on initiation of transcription by NF-κB. © 2005 Cancer Research UK.

The contract management responsibility system in China : an institutional interpretation

Thesis is about the enterprise reform in China in general, and the Contract Management Responsibility System (the CMRS) in particular. The latter is a new institutional arrangement to deal with the relation between the government and the state-owned enterprise which has always been at the centre of the enterprise reform. The focus of the research is on the process of institutionalization in order to study the problems of the emergence of a free enterprise system in China. The research is conducted by four in-depth case studies to reveal how the CMRS is running and what interaction is taking place between the government and the state-owned enterprise under the system. Drawing on the empirical work, the thesis analyzes the features of the CMRS and the characteristics of its implementation process with respect to the structural-institutional paradigm, and the property rights approach. The research shows that to establish a market-type relation between the government and the enterprise is a complicated and dynamic process. It involves the understanding of the two different economic mechanisms, market and planning, and the interations taken by two parties. It concludes that the CMRS is an unstable system, either going back to the previous system or moving towards a market system, because its dynamic and control dimension are dysfunctional.

Interaction of peptides, peptidomimetics and other drug candidates with the DI/tripeptide transport system in intestinal epithelial cells, using the in vitro caco-2 cell culture system

An uptake system was developed using Caco-2 cell monolayers and the dipeptide, glycyl-[3H]L-proline, as a probe compound. Glycyl-[3H]L-proline uptake was via the di-/tripeptide transport system (DTS) and, exhibited concentration-, pH- and temperature-dependency. Dipeptides inhibited uptake of the probe, and the design of the system allowed competitors to be ranked against one another with respect to affinity for the transporter. The structural features required to ensure or increase interaction with the DTS were defined by studying the effect of a series of glycyl-L-proline and angiotensin-converting enzyme (ACE)-inhibitor (SQ-29852) analogues on the uptake of the probe. The SQ-29852 structure was divided into six domains (A-F) and competitors were grouped into series depending on structural variations within specific regions. Domain A was found to prefer a hydrophobic function, such as a phenyl group, and was intolerant to positive charges and H+ -acceptors and donors. SQ-29852 analogues were more tolerant of substitutions in the C domain, compared to glycyl-L-proline analogues, suggesting that interactions along the length of the SQ-29852 molecule may override the effects of substitutions in the C domain. SQ-29852 analogues showed a preference for a positive function, such as an amine group in this region, but dipeptide structures favoured an uncharged substitution. Lipophilic substituents in domain D increased affinity of SQ-29852 analogues with the DTS. A similar effect was observed for ACE-NEP inhibitor analogues. Domain E, corresponding to the carboxyl group was found to be tolerant of esterification for SQ-29852 analogues but not for dipeptides. Structural features which may increase interaction for one series of compounds, may not have the same effect for another series, indicating that the presence of multiple recognition sites on a molecule may override the deleterious effect of anyone change. Modifying current, poorly absorbed peptidomimetic structures to fit the proposed hypothetical model may improve oral bioavailability by increasing affinity for the DTS. The stereochemical preference of the transporter was explored using four series of compounds (SQ-29852, lysylproline, alanylproline and alanylalanine enantiomers). The L, L stereochemistry was the preferred conformation for all four series, agreeing with previous studies. However, D, D enantiomers were shown in some cases to be substrates for the DTS, although exhibiting a lower affinity than their L, L counterparts. All the ACE-inhibitors and β-lactam antibiotics investigated, produced a degree of inhibition of the probe, and thus show some affinity for the DTS. This contrasts with previous reports that found several ACE inhibitors to be absorbed via a passive process, thus suggesting that compounds are capable of binding to the transporter site and inhibiting the probe without being translocated into the cell. This was also shown to be the case for oligodeoxynucleotide conjugated to a lipophilic group (vitamin E), and highlights the possibility that other orally administered drug candidates may exert non-specific effects on the DTS and possibly have a nutritional impact. Molecular modelling of selected ACE-NEP inhibitors revealed that the three carbonyl functions can be oriented in a similar direction, and this conformation was found to exist in a local energy-minimised state, indicating that the carbonyls may possibly be involved in hydrogen-bond formation with the binding site of the DTS.

The development of the visual system in pre-term infants as assessed by electrophysiological techniques

In an endeavour to provide further insight into the maturation of the human visual system, the contiguous development of the pattern reversal VEP, flash VEP and flash ERG was studied in a group of neurologically normal pre-term infants, born between 28 and 35 weeks gestation. Maturational changes were observed in all the evoked electrophysiological responses recorded, these were mainly characterised by an increase in the complexity of the waveform and a shortening in the latency of the response. Initially the ERG was seen to consist of a broad b-wave only, with the a-wave emerging at an average age of 40 weeks PMA. The a-wave showed only a slight reduction in latency and a modest increase in amplitude as the infant grows older, whereas the changes seen in the ERG b-wave were much more dramatic. Pattern reversal VEPs were successfully recorded for the first time during the pre-term period. Flash VEPs were also recorded for comparison. The neonatal pattern reversal VEP consistently showed a major positive component (P1) of long latency. As the infant grew older, the latency of the P1 component decreased and was found to be negatively correlated with PMA at recording. The appearance of the N1 and N2 components became more frequent as the infant matured. The majority of infants were found to be myopic at birth and refractive error was correlated with PMA, with emmetropisation occurring at about 45 weeks PMA. The pattern reversal VEP in response to 2o checks was apparently unaffected by refractive error.

Development of a computerised library system in the construction industry

This thesis examines the ways that libraries have employed computers to assist with housekeeping operations. It considers the relevance of such applications to company libraries in the construction industry, and describes more specifically the development of an integrated cataloguing and loan system. A review of the main features in the development of computerised ordering, cataloguing and circulation control systems shows that fully integrated packages are beginning to be completed, and that some libraries are introducing second generation programs. Cataloguing is the most common activity to be computerised, both at national and company level. Results from a sample of libraries in the construction industry suggest that the only computerised housekeeping system is at Taylor Woodrow. Most of the firms have access to an in-house computer, and some of the libraries, particularly those in firms of consulting engineers, might benefit from computerisation, but there are differing attitudes amongst the librarians towards the computer. A detailed study of the library at Taylor Woodrow resulted in a feasibility report covering all the areas of its activities. One of the main suggestions was the possible use of a computerised loans and cataloguing system. An integrated system to cover these two areas was programmed in Fortran and implemented. This new system provides certain benefits and saves staff time, but at the cost of time on the computer. Some improvements could be made by reprogramming, but it provides a general system for small technical libraries. A general equation comparing costs for manual and computerised operations is progressively simplified to a form where the annual saving from the computerised system is expressed in terms of staff and computer costs and the size of the library. This equation gives any library an indication of the savings or extra cost which would result from using the computerised system.

An integral equation method for a mixed initial boundary value problem for unsteady Stokes system in a doubly-connected domain

We present a novel numerical method for a mixed initial boundary value problem for the unsteady Stokes system in a planar doubly-connected domain. Using a Laguerre transformation the unsteady problem is reduced to a system of boundary value problems for the Stokes resolvent equations. Employing a modied potential approach we obtain a system of boundary integral equations with various singularities and we use a trigonometric quadrature method for their numerical solution. Numerical examples are presented showing that accurate approximations can be obtained with low computational cost.

Feasibility study for the implementation of a G. T. system in a multi-product company

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