885 resultados para Inducers of resistance


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Fungi are ubiquitous organisms in nature and can be found in association with healthy eyes. The incidence of actual fungal infection of the eye, however, is relatively low compared with that attributable to viruses and bacteria. Nevertheless, fungal infection of the eye is increasing especially in immuno-compromised patients and a wide variety of fungal infections have now been described worldwide with species of Fusarium, Aspergillus, Candida, and dematiaceous fungi predominating. At present there are a limited number of compounds available to control ocular mycoses while resistance to anti-fungal agents has been growing in recent years, especially to azoles. Several mechanisms of resistance have been identified including modification of sterol synthesis pathways by the fungus, modification of enzymes to reduce the binding of azoles to fungal components and increased efficiency of removal of the azole within fungal cells. Although resistance to amphotericin-B has been reported, it continues to be the most important treatment for life-threatening conditions and more severe ophthalmic infections. Natamycin is often first choice for filamentous fungal keratitis and topical amphotericin-B for Candida keratitis. Continued monitoring of the behaviour of ocular fungi will be essential in future together with the development of new anti-fungal agents.

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Emerging markets have recently been experiencing a dramatic increased in the number of mobile phone per capita. M-government has, hence, been heralded as an opportunity to leap-frog the technology cycle and provide cheaper and more inclusive and services to all. This chapter explores, within an emerging market context, the legitimacy and resistance facing civil servants’ at the engagement stage with m-government activities and the direct implication for resource management. Thirty in depth interview, in Turkey, are drawn-upon with key ICT civil servant in local organizations. The findings show that three types of resources are perceived as central namely: (i) diffusion of information management, (ii) operating system resource management and (iii) human resource management. The main evidence suggests that legitimacy for each resource management, at local level, is an ongoing struggle where all groups deploy multiples forms of resistance. Overall, greater attention in the resource management strategy for m-government application needs to be devoted to enablers such as civil servants rather than the final consumers or citizens.

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Alteration in the target sites of antibiotics is a common mechanism of resistance. Examples of clinical strains showing resistance can be found for every class of antibiotic, regardless of the mechanism of action. Target site changes often result from spontaneous mutation of a bacterial gene on the chromosome and selection in the presence of the antibiotic. Examples include mutations in RNA polymerase and DNA gyrase, resulting in resistance to the rifamycins and quinolones, respectively. In other cases, acquisition of resistance may involve transfer of resistance genes from other organisms by some form of genetic exchange (conjugation, transduction, or transformation). Examples of these mechanisms include acquisition of the mecA genes encoding methicillin resistance in Staphylococcus aureus and the various van genes in enterococci encoding resistance to glycopeptides. © 2005 Elsevier B.V. All rights reserved.

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The thesis explores the nature of pupil resistance; it investigates what constitutes it and how it can be explained. Various ethnic and national group, male and female working-class resistance if analysed in two secondary schools in Birmingham (England) and one school in Sydney (Australia). It focuses on the pupils’ experience of school. ‘Compressed ethnographies’ (Walford and Miller, 1991) were conducted in each school to examine pupil resistance. The research found that structural societal state factors, regional, community and formal, informal and physical characteristics of each school, together with the teachers and pupils characteristics and background all influence resistance. The class, gender, ethnic and national identity of each pupil shapes resistance. In all three schools that were involved with the research, girls were more likely to exhibit overt, collective forms of resistance, whereas lads were more likely to operate alone. Islander pupils in Sydney and African-Caribbean kids in Birmingham were more likely to display engaged forms of resistance. Girls tended to show more engaged forms compared to their male counterparts across all ethnic and national cultures. Resistance is complex and dynamic, the definition alters depending upon context. Dimensions of resistance are developed; including overt, covert; individual, collective; intentional, unintentional; engaged and detached forms. Resistance operates within a structure and agency framework, the pupils can shape their own schooling experience mediated within the structures of their school, community and society. Some pupils manage their resources and the structures better than others; how the pupil manages and operates within the structures influences their resistance response. Resistance is contradictory and can reinforce the status quo. To fully understand resistance, it must be contextualised.

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Bacterial resistance to antibiotics and biocides is a prevalent problem, which may be exacerbated by the commonplace and often unnecessary inclusion of biocides into domestic products. Addition of antimicrobials, to domestic disinfectants has raised concern about promoting microbial resistance and potential cross-resistance to therapeutic antibiotics. This study investigated the potential for resistance in Salmonella enterica serovars Enteritidis, Typhimurium, Virchow and Escherichia call 0157 to commonly used biocides, to identify mechanisms underlying resistance and whether these provided cross-resistance to antibiotics. Salmonella enterica and E. coli 0157 strains were serially exposed to sub-inhibitory. concentrations of erythromycin (ERY), benzalkonium chloride (BKC), chlorhexidine hydrochloride (CHX)and triclosan (TLN). Once resistance was achieved permeability changes in the outer membrane, including LPS, cell surface charge and hydrophobicityand the presence of,an active efflux were investigated as possible resistance candidates. Thin layer chromatography (TLC) and Gas chromatography (GC) were carried out to examine fatty acid and lipid changes in E. coli 0157 isolates with reduced susceptibility to TLN. Cross-resistance was studied by the Stoke's method and standard microdilution assays. Examination of the outer membrane proteins and LPS did not reveal any significant changes between parent and resistant strains. The hydrophobicity of the cells increased as the cells were passaged and became less. susceptible. An active efflux system was the most likely mechanism of resistance in all strains tested and a fab1 mutation was associated with E. coli 0157 resistant to TLN isolates. In all isolates investigated the resistance was stable for over 30 passages in biocide-free media. A high degree of cross-resistance was obtained in TLN-resjstant Escherichia coli 0157 strains, which repeatedly exerted decreased susceptibility to various antimicrobials, including chloramphenicol, erythromycin, imipenem, tetracycline and trimethoprirn:, as well as to various biocides. The results of this laboratory-based investigation suggest that it is possible for microorganisms to become resistant to biocides when repeatedly exposed to sublethal concentrations. This may be especially the case in the domestic environment where administration of biocides is poorly controlled. Eventually it could lead to the undesirable situation of resident strains becoming resistant to disinfection and cross resistant to other antimicrobials.

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Burkholderia cepacia is an opportunistic pathogen that colonises of the lungs of cystic fibrosis (CF) patients, with a frequently fatal outcome. Antibiotic resistance is common and highly transmissible epidemic strains have been described in the UK. 37 B. cepacia isolates from clinical and botanical sources were characterised via metabolic capabilities, antibiotic sensitivity, fatty acid methyl ester (FAME) profiles restriction digest analysis of chromosomal DNA by pulsed-gel electrophoresis (PFGE) (with the use of two separate restriction enzymes) and outer membrane protein (OMP) profiles. This revealed isolates of the UK CF epidemic strain to form a distinct group with a specific OMP profile. Cluster analysis of PFGE and FAME profiles revealed the species Burkholderia gladioli and Burkholderia vietnamiensis to be more closely related to each other and to laboratory strains of B. cepacia than to the CF epidemic strain considered a member of the latter species. The epidemic strain of B. cepacia may therefore be worthy of species definition in its own right. All the strains studied showed a high level of resistance to antibiotics, including the carbapenems. Considering this, carbapenemase production by isolates of B. cepacia was investigated. A metallo-β-lactamase from a clinical strain of B. cepacia was isolated and partially purified of using Cibacron blue F3GA-coupled agarose. The resulting preparation showed a single band of β-lactamase activity (pI 8.45) after analytical isoelectric focusing. The enzyme was particularly effective in the hydrolysis of imipenem. Meropenem, biapenem, cephaloridine, ceftazidime, benzylpenicillin, ampicillin and carbenicillin were hydrolysed at a lower rate. An unusual inhibition profile was noted. Inhibition by the metal ion chelators ethylene diamine tetra acetic acid and o-phenanthroline was reversed by addition of zinc, indicating a metallo-enzyme, whilst >90% inhibition was attainable with 0.1mM concentrations of tazobactam and clavulanic acid. A study of 8 other clinical isolates showed an enzyme of pI 8.45 to be present and inducible by imipenem in each case. This enzyme was assigned PCM-I (Pseudomonas cepacia metalloenzyme I).

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The process of astrogliosis, or reactive gliosis, is a typical response of astrocytes to a wide range of physical and chemical injuries. The up-regulation of the astrocyte specific glial fibrillary acidic protein (GFAP) is a hallmark of reactive gliosis and is widely used as a marker to identify the response. In order to develop a reliable, sensitive and high throughput astrocyte toxicity assay that is more relevant to the human response than existing animal cell based models, the U251-MG, U373-MG and CCF-STTG 1 human astrocytoma cell lines were investigated for their ability to exhibit reactive-like changes following exposure to ethanol, chloroquine diphosphate, trimethyltin chloride and acrylamide. Cytotoxicity analysis showed that the astrocytic cells were generally more resistant to the cytotoxic effects of the agents than the SH-SY5Y neuroblastoma cells. Retinoic acid induced differentiation of the SH-SY5Y line was also seen to confer some degree of resistance to toxicant exposure, particularly in the case of ethanol. Using a cell based ELISA for GFAP together with concurrent assays for metabolic activity and cell number, each of the three cell lines responded to toxicant exposure by an increase in GFAP immunoreactivity (GFAP-IR), or by increased metabolic activity. Ethanol, chloroquine diphosphate, trimethyltin chloride and bacterial lipopolysaccharide all induced either GFAP or MTT increases depending upon the cell line, dose and exposure time. Preliminary investigations of additional aspects of astrocytic injury indicated that IL-6, but not TNF-α. or nitric oxide, is released following exposure to each of the compounds, with the exception of acrylamide. It is clear that these human astrocytoma cell lines are capable of responding to toxicant exposure in a manner typical of reactive gliosis and are therefore a valuable cellular model in the assessment of in vitro neurotoxicity.

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This thesis is based on ethnographic research carried out on a Liverpool protest movement which occurred between November, 1980 and July,1983. The protest movement was waged by residents of the working class community of Croxteth Liverpool who wished to retain their state secondary school, Croxteth Comprehensive. The Liverpool City Council voted in favour of closing Croxteth Comprehensive in January, 1981 because of its declining roles. Residents began theIr campaign as soon as they became aware of intentions to close the school at the end of the previous year. The campaIgn itself went through a number of different phases, distinguishable accordIng to the groups of people involved, the strategy and tactics they employed, the ways in which they justified their campaign, and the goals they pursued. In July of 1982 the organisation which led the protest, the Croxteth Community Action Committee, took illegal possession of the school buildings and ran a pilot summer school project. In September of 1982 they opened the school doors for all secondary pupils on the council estate and began running classes, with the help of volunteer teachers. The school was run successfully in this way for the entire 1982/83 school year. By the end of this period the school was officially reinstated by a new Labour Party majorIty on the city council. This thesis presents a comprehensive account of the entire campaign, from its beginning to end. The campaign is analysed in a number of ways: by situating the closure itself in the economic and political conditions of Liverpool in the 1980s, by examining the relation of Croxteth Comprehensive to its community, by describing the conditions in which different groups of people contributed to the campaign and the changes it went through in its use of tactics, and through a close examination of the activities which took place inside the school during its year of occupation. A number of levels of analysis are used in the study. To explain the closure and the early forms of resistance which developed to oppose it, the structural location of the local government of Liverpool in the late 1970s and early 1980s is described. To explain the relationship of the school to its community, the formation of a group of activists and their leaders, and the resources available to the protestors for pursuing their aims, a single-group model of social action is used. To analyse the establishment of social routines and schooling practices within the school during its occupation, action-theoretica1 models are drawn upon., The chapters of literature review and concept analysis with which this thesis begins link these different levels theoretIcalIy through a model of actIon and its conditions. The theoretical framework employed is reviewed in the last chapter. It is one which could be used to study any social movement, and has applications to other social phenomena as well. Lastly various issues within the sociology of education are examined in light of the events which took place in Croxteth Comprehensive, especially the theory of community education.

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Representations of voluntary childlessness — the declaration by an individual that he or she does not wish to bear or raise children — were studied in 116 articles published in British national newspapers in the period 1990—2008. Media framing analysis was used to examine broad patterns of framing of the topic, identifying four frames: voluntary childlessness as an individual rights issue, as a form of resistance, as a social trend, and as a personal decision. These frames, it is argued, may act as potential ‘scripts’ for newspaper readers who are debating the decision to start a family.

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This thesis examines the parameters associated with the failure of triangular steel gusset plates. Eighty two results are presented investigating the position of the applied load, the gusset plate height to length ratio, size, thickness, internal angle and the removal of the inside corner. The thickness of the loaded plate and its influence on the gusset plates failure is also investigated. Twenty two similar gusset plates were tested to investigate the welds connecting the gusset plate to the adjacent loaded and support edges. The experimental results are compared with existing methods, none of which cover all the variables tested. Some methods do not consider buckling and most of those that do are inadequate. Most of the methods do not accurately take account of the load position. An alternative method based on experimental observations is presented for design purposes. The method covers any combination of the variables tested. To test assumptions made in the theoretical work forty seven strut tests took place to investigate buckling characteristics and fifteen special gusset plates were also tested. The gusset plates were found to fail in an elastic-plastic buckling manner. A gusset plate has a specific moment of resistance capacity about it’s inside corner and the ultimate load that can be applied is dependent upon the position of the load relative to the supported edge. There is an optimum height to length ratio for strength and any increase in the internal angle from 90 degrees produces little change in moment capacity. The removal of small portions of the inside corner of a gusset plate has little effect upon its moment capacity. The loaded plate does not provide any significant moment of resistance to the applied load at failure. The main functions of the loaded and supported edge welds is to prevent the gusset plate from slipping from between the plates.

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The thesis describes a programme of research designed to identify concretes for application at cryogenic temperature, in particular for storage of Liquefield Natural Gas which is maintained at a temperature of -165oC. The programme was undertaken in two stages. Stage 1 involved screening tests on seventeen concrete mixes to investigate the effects of strength grade (and water/cement ratio), air entrainment, aggregate type and cement type. Four mixes were selected on the basis of low temperature strength, residual strength after thermal cycling and permeability at ambient temperature. In Stage 2 the selected mixes were subjected to a comprehensive range of tests to measure those properties which determine the leak tightness of a concrete tank at temperatures down to -165oC. These included gas permeability; tensile strength, strain capacity, thermal expansion coefficient and elastic modulus, which in combination provide a measure of resistance to cracking; and bond to reinforcement, which is one of the determining factors regarding crack size and spacing. The results demonstrated that the properties of concrete were generally enhanced at cryogenic temperature, with reduced permeability, reduced crack proneness and, by virtue of increased bond to reinforcement, better control of cracking should it occur. Of the concretes tested, a lightweight mix containing sintered PFA aggregate exhibited the best performance at ambient and cryogenic temperature, having appreciably lower permeability and higher crack resistance than normal weight concretes of the same strength grade. The lightweight mix was most sensitive to thermal cycling, but there was limited evidence that this behaviour would not be significant if the concrete was prestressed. Relationships between various properties have been identified, the most significant being the reduction in gas permeability with increasing strain capacity. The structural implications of the changing properties of the concrete have also been considered.

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It stands to reason that critical theorists should be interested in the newest student movements working to challenge the neoliberalisation of higher education. Yet, while these politics are pushing the limits of critical knowledge about the cultivation of new modalities of radical political resistance, their theoretical significance remains marginalised within the academy. While the academic literature is replete with analysis of the long-anticipated ‘crisis of the university’, many professional responses to the most recent privatisation policies have been muted and ambivalent; or, at the very least, hopeful that the trends can be arrested or mitigated by sanctioned operations of professional critique and opposition. In this essay, I suggest that some of the recent work of student activists demonstrates both the contingency of this position and the possibility of cultivating new political subjectivities and critical-experimental modalities of resistance, within and beyond the university.

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This essay examines how academics and students in England have been primed to comply with a political agenda of “deep” neoliberalization through cumulative processes of institutional and subjective undermining and considers what might be an appropriate logic of critical response. It first describes how the embedding of principles and mechanisms of market governance within academic life has depoliticized methods for critically theorizing and collectively resisting these processes and then explores the work of recent student-led opposition to the British government’s new policies, teasing out some theoretical implications of the logic of occupation being cultivated there. It suggests that by fusing a determination for autonomy with a transgressive cultivation of new forms of thinking and social practice, the occupations illustrate new critical-experimental work in the politics of possibility. The underlying logic thus offers some resources for reimagining modalities of resistance to processes of deep neoliberalization; however, becoming receptive to them may also require a critique of professional academic subjectivities and reevaluation of attachments to existing forms of the university itself.

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Cardiovascular disease (CVD) continues to be one of the top causes of mortality in the world. World Heart Organization (WHO) reported that in 2004, CVD contributed to almost 30% of death from estimated worldwide death figures of 58 million[1]. Heart failure treatment varies from lifestyle adjustment to heart transplantation; its aims are to reduce HF symptoms, prolong patient survival and minimize risk [2]. One alternative available in the market for HF treatment is Left Ventricular Assist Device (LVAD). Chronic Intermittent Mechanical Support (CIMS) device is a novel (LVAD) heart failure treatment using counterpulsation similar to Intra Aortic Balloon Pumps (IABP). However, the implantation site of the CIMS balloon is in the ascending aorta just distal to aortic valve contrasted with IABP in the descending aorta. Counterpulsation coupled with implantation close to the aortic valve enables comparable flow augmentation with reduced balloon volume. Two prototypes of the CIMS balloon were constructed using rapid prototyping: the straight-body model is a cylindrical tube with a silicone membrane lining with zero expansive compliance. The compliant-body model had a bulging structure that allowed the membrane to expand under native systolic pressure increasing the device’s static compliance to 1.5 mL/mmHg. This study examined the effect of device compliance and vascular compliance on counterpulsating flow augmentation. Both prototypes were tested on a two-element Windkessel model human mock circulatory loop (MCL). The devices were placed just distal to aortic valve and left coronary artery. The MCL mimicked HF with cardiac output of 3 L/min, left ventricular pressure of 85/15 mmHg, aortic pressure of 70/50 mmHg and left coronary artery flow rate of 66 mL/min. The mean arterial pressure (MAP) was calculated to be 57 mmHg. Arterial compliance was set to be1.25 mL/mmHg and 2.5 mL/mmHg. Inflation of the balloon was triggered at the dicrotic notch while deflation was at minimum aortic pressure prior to systole. Important haemodynamics parameters such as left ventricular pressure (LVP), aortic pressure (AoP), cardiac output (CO), left coronary artery flowrate (QcorMean), and dP (Peak aortic diastolic augmentation pressure – AoPmax ) were simultaneously recorded for both non-assisted mode and assisted mode. ANOVA was used to analyse the effect of both factors (balloon and arterial compliance) to flow augmentation. The results showed that for cardiac output and left coronary artery flowrate, there were significant difference between balloon and arterial compliance at p < 0.001. Cardiac output recorded maximum output at 18% for compliant body and stiff arterial compliance. Left coronary artery flowrate also recorded around 20% increase due to compliant body and stiffer arterial compliance. Resistance to blood ejection recorded highest difference for combination of straight body and stiffer arterial compliance. From these results it is clear that both balloon and arterial compliance are statistically significant factors for flow augmentation on peripheral artery and reduction of resistance. Although the result for resistance reduction was different from flow augmentation, these results serves as an important aspect which will influence the future design of the CIMS balloon and its control strategy. References: 1. Mathers C, Boerma T, Fat DM. The Global Burden of disease:2004 update. Geneva: World Heatlh Organization; 2008. 2. Jessup M, Brozena S. Heart Failure. N Engl J Med 2003;348:2007-18.

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This article explores gender politics and processes in the academy and investigates change from the perspectives of feminist academics. In particular, it explores the experiences of women academics attempting to effect change to the gendered status quo of their own institutions. Focusing on micro-politics, the feminist movement is empirically explored in localized spaces of resistance and in the small but significant individual efforts at making changes in academic institutions. The analysis is based on interviews with female academics working in business and management schools and focuses on the challenges for change and how change attempts affect their personal and professional identities. The article explores the range of change strategies that participants use as they try to progress in their academic career while staying true to their feminist values and priorities through both resisting and incorporating dominant discourses of academic work. The analysis highlights such tensions and focuses on a contextualized, bottom-up perspective on change that, unlike more totalizing theorization, takes into account mundane and lived experiences at the level of the individual. © 2012 Blackwell Publishing Ltd.