19 research outputs found
Automation and validation of micronucleus detection in the 3D EpiDerm human reconstructed skin
No full textRecent restrictions on the testing of cosmetic ingredients in animals have resulted in the need to test the genotoxic potential of chemicals exclusively in vitro prior to licensing. However, as current in vitro tests produce some misleading positive results, sole reliance on such tests could prevent some chemicals with safe or beneficial exposure levels from being marketed. The 3D human reconstructed skin micronucleus (RSMN) assay is a promising new in vitro approach designed to assess genotoxicity of dermally applied compounds. The assay utilises a highly differentiated in vitro model of the human epidermis. For the first time, we have applied automated micronucleus detection to this assay using MetaSystems Metafer Slide Scanning Platform (Metafer), demonstrating concordance with manual scoring. The RSMN assay's fixation protocol was found to be compatible with the Metafer, providing a considerably shorter alternative to the recommended Metafer protocol. Lowest observed genotoxic effect levels (LOGELs) were observed for mitomycin-C at 4.8 μg/ ml and methyl methanesulfonate (MMS) at 1750 μg/ml when applied topically to the skin surface. In-medium dosing with MMS produced a LOGEL of 20 μg/ml, which was very similar to the topical LOGEL when considering the total mass of MMS added. Comparisons between 3D medium and 2D LOGELs resulted in a 7-fold difference in total mass of MMS applied to each system, suggesting a protective function of the 3D microarchitecture. Interestingly, hydrogen peroxide (H2O 2), a positive clastogen in 2D systems, tested negative in this assay. A non-genotoxic carcinogen, methyl carbamate, produced negative results, as expected. We also demonstrated expression of the DNA repair protein N-methylpurine-DNA glycosylase in EpiDerm™. Our preliminary validation here demonstrates that the RSMN assay may be a valuable followup to the current in vitro test battery, and together with its automation, could contribute to minimising unnecessary in vivo tests by reducing in vitro misleading positives. © The Author 2014
Belonging and not belonging : understanding India in novels by Paul Scott, Ruth Prawer Jhabvala and V.S. Naipaul.
No full textPhDThis thesis is essentially about the "how" and "why" of the Indian
experience as documented in novels by Paul Scott, Ruth Prawer Jhabvala
and V S Naipaul. The study points to the difficulty of arriving at any
conclusive definition of the country and its people. I show that
differences in attitudes, responses or behaviour are both overt and
subtle, and depend upon whether the writer or the character identifies
with the situation or community with which he or she interacts. It is
the individual's sense of belonging or not belonging to his or her own
group - be this along racial, cultural or gender lines - that accounts
for the differing perspectives evident in these novels. The points-of-
view of the outsider and the insider can therefore be seen as
mutual comments upon the other.
Since the struggle between belonging and not belonging becomes acute
when the old meets the new, focus is centred on communities
experiencing change. These include the British in India, West-Indian
Indians and westernised Indians. Despite their differences, all three
communities share similar reasons for either an acceptance or
rejection of the 'Other'. The thesis argues that the need for
emotional stability compels allegiance to the traditional group, while
the desire for individuality encourages surrender to the new. The
former nurtures a sense of belonging while, it is argued, that the
latter is perceived as the hallmark of those who do not belong.
Tensions arise when both these needs demand to be met. What I show to
be ironic in this struggle between belonging and not belonging is that
those things which individuals overtly reject are often unexpressed
parts of their personal pysche. The barrier between "them" and "us" is
therefore very fragile
Influence of DNA Repair on Nonlinear Dose-Responses for Mutation
No full textRecent evidence has challenged the default assumption that all DNA-reactive alkylating agents exhibit a linear dose-response. Emerging evidence suggests that the model alkylating agents methyl- and ethylmethanesulfonate and methylnitrosourea (MNU) and ethylnitrosourea observe a nonlinear dose-response with a no observed genotoxic effect level (NOGEL). Follow-up mechanistic studies are essential to understand the mechanism of cellular tolerance and biological relevance of such NOGELs. MNU is one of the most mutagenic simple alkylators. Therefore, understanding the mechanism of mutation induction, following low-dose MNU treatment, sets precedence for weaker mutagenic alkylating agents. Here, we tested MNU at 10-fold lower concentrations than a previous study and report a NOGEL of 0.0075μg/ml (72.8nM) in human lymphoblastoid cells, quantified through the hypoxanthine (guanine) phosphoribosyltransferase assay (OECD 476). Mechanistic studies reveal that the NOGEL is dependent upon repair of O6-methylguanine (O6MeG) by the suicide enzyme O6MeG-DNA methyltransferase (MGMT). Inactivation of MGMT sensitizes cells to MNU-induced mutagenesis and shifts the NOGEL to the left on the dose axis. © The Author 2013. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved
A Case Study of the Population Ecology of a Topmouth Gudgeon (Pseudorasbora parva) Population in the UK and the Implication for Native Fish Communities
No full text1. The topmouth gudgeon Pseudorasbora parva is a small Asian cyprinid species that has proved invasive throughout many European countries. Following an initial introduction into the wild in 1996, the species is now proving invasive in the UK, with at least 25 infested waters in England and Wales, of which 10 are known to have direct connection to a major river catchment.
2. To demonstrate the threat of P. parva to fisheries in the UK, a case study is presented on a lake located in the Lake District of England where the species was introduced in 2000. The species rapidly established a breeding population that, by 2003, was the dominant species in size classes <70 mm. In 2004, they were the only species in the lake that produced young-of-the-year.
3. Individual P. parva adopted the reproductive tactics of early maturity, multiple spawning, male dominance and male nest guarding; sexual dimorphism was manifested in larger body size of males. These traits were in contrast to the resident, native species of the lake, including roach Rutilus rutilus and gudgeon Gobio gobio, which adopted traits of later maturity and single spawning.
4. This case study, therefore, revealed relatively rapid establishment of a P. parva population, their subsequent numerical dominance of the fish community, and the impediment of the recruitment of native fish. The implications for UK fisheries are concerning: should P. parva continue to disperse and individuals adopt similar traits as those in this case study, there may be few waters immune from their invasion, numerical dominance and subsequent impacts
Conductors of the Cape Town Municipal Orchestra, 1914-1965 a historical perspective
No full textIncludes abstract.Includes bibliographical references and index.This thesis profiles the conductors of the Cape Municipal Orchestra since its inception in 1914 until the resignation of David Tidboald in 1965. After the introductory Chapter 1, Chapter 2 includes a historic review of the period before 1914. It also highlights the influences leading towards the inauguration of the Cape Municipal Orchestra. Chapters 3-7 discuss the permanent conductors who conducted between 1914 and 1954. The following list extends from the dates of their first concerts up to their resignations, or up to the date of their final concerts: Theo Wendt (from 28 February 1914 to 30 September 1924: a period of about 10 years). Leslie Heward (from 17 July 1924 to 31 May 1926: a period of about 2 years). William Pickerill (from 5 May 1927 to 12 October 1946: a period of about 19 years). Geoffrey Miller as Associate Conductor (from 31 October 1946 to 19 February1948: a period of nearly two years). Enrique Jordá (from 19 February 1948 to 31 December 1953: a period of nearly five years). Assistant and guest conductors are discussed within these chapters. Chapter 8 discusses guest conductors from January 1954 until June 1960. Here they are organised chronologically accordingto their first appearances. Chapter 9 deals with the period of David Tidboald's conductorship (from 20 August 1960 to1 July 1965). The concluding remarks of Chapter 10 briefly touch on such aspects as the number of premieres, recurrence of works mentioned in this thesis, and the guest conducting system
DNA Glycosylases Involved in Base Excision Repair May Be Associated with Cancer Risk in BRCA1 and BRCA2 Mutation Carriers.
No full textSingle Nucleotide Polymorphisms (SNPs) in genes involved in the DNA Base Excision Repair (BER) pathway could be
associated with cancer risk in carriers of mutations in the high-penetrance susceptibility genes BRCA1 and BRCA2, given the relation of synthetic lethality that exists between one of the components of the BER pathway, PARP1 (poly ADP ribose
polymerase), and both BRCA1 and BRCA2. In the present study, we have performed a comprehensive analysis of 18 genes involved in BER using a tagging SNP approach in a large series of BRCA1 and BRCA2 mutation carriers. 144 SNPs were analyzed in a two stage study involving 23,463 carriers from the CIMBA consortium (the Consortium of Investigators of Modifiers of BRCA1 and BRCA2). Eleven SNPs showed evidence of association with breast and/or ovarian cancer at p,0.05 in the combined analysis. Four of the five genes for which strongest evidence of association was observed were DNA glycosylases. The strongest evidence was for rs1466785 in the NEIL2 (endonuclease VIII-like 2) gene (HR: 1.09, 95% CI (1.03– 1.16), p = 2.761023) for association with breast cancer risk in BRCA2 mutation carriers, and rs2304277 in the OGG1 (8-guanine DNA glycosylase) gene, with ovarian cancer risk in BRCA1 mutation carriers (HR: 1.12 95%CI: 1.03–1.21,
p = 4.861023). DNA glycosylases involved in the first steps of the BER pathway may be associated with cancer risk in BRCA1/ 2 mutation carriers and should be more comprehensively studied
The role of intracellular trafficking of CdSe/ZnS QDs on their consequent toxicity profile
No full textBackground: Nanoparticle interactions with cellular membranes and the kinetics of their transport and localization are important determinants of their functionality and their biological consequences. Understanding these phenomena is fundamental for the translation of such NPs from in vitro to in vivo systems for bioimaging and medical applications. Two CdSe/ZnS quantum dots (QD) with differing surface functionality - (NH2 or COOH moieties) were used here for investigating the intracellular uptake and transport kinetics of these QDs.
Results: In water, the COOH- and NH2-QDs were negatively and positively charged, respectively, while in serum-containing medium the NH2-QDs were agglomerated, whereas the COOH- QDs remained dispersed. Though intracellular levels of NH2- and COOH-QDs were very similar after 24 h exposure, COOH-QDs appeared to be continuously internalised and transported by endosomes and lysosomes, while NH2-QDs mainly remained in the lysosomes. The results of (intra) cellular QD trafficking were correlated to their toxicity profiles investigating levels of reactive oxygen species (ROS), mitochondrial ROS, autophagy, changes to cellular morphology and alterations in genes involved in cellular stress, toxicity and cytoskeletal integrity. The continuous flux of COOH-QDs perhaps explains their higher toxicity compared to the NH2-QDs, mainly resulting in mitochondrial ROS and cytoskeletal remodelling which are phenomena that occur early during cellular exposure.
Conclusions: Together, these data reveal that although cellular QD levels were similar after 24 h, differences in the nature and extent of their cellular trafficking resulted in differences in consequent gene alterations and toxicological effects
Critical research gaps and translational priorities for the successful prevention and treatment of breast cancer
No full textIntroductionBreast cancer remains a significant scientific, clinical and societal challenge. This gap analysis has reviewed and critically assessed enduring issues and new challenges emerging from recent research, and proposes strategies for translating solutions into practice. MethodsMore than 100 internationally recognised specialist breast cancer scientists, clinicians and healthcare professionals collaborated to address nine thematic areas: genetics, epigenetics and epidemiology; molecular pathology and cell biology; hormonal influences and endocrine therapy; imaging, detection and screening; current/novel therapies and biomarkers; drug resistance; metastasis, angiogenesis, circulating tumour cells, cancer ‘stem’ cells; risk and prevention; living with and managing breast cancer and its treatment. The groups developed summary papers through an iterative process which, following further appraisal from experts and patients, were melded into this summary account. ResultsThe 10 major gaps identified were: (1) understanding the functions and contextual interactions of genetic and epigenetic changes in normal breast development and during malignant transformation; (2) how to implement sustainable lifestyle changes (diet, exercise and weight) and chemopreventive strategies; (3) the need for tailored screening approaches including clinically actionable tests; (4) enhancing knowledge of molecular drivers behind breast cancer subtypes, progression and metastasis; (5) understanding the molecular mechanisms of tumour heterogeneity, dormancy, de novo or acquired resistance and how to target key nodes in these dynamic processes; (6) developing validated markers for chemosensitivity and radiosensitivity; (7) understanding the optimal duration, sequencing and rational combinations of treatment for improved personalised therapy; (8) validating multimodality imaging biomarkers for minimally invasive diagnosis and monitoring of responses in primary and metastatic disease; (9) developing interventions and support to improve the survivorship experience; (10) a continuing need for clinical material for translational research derived from normal breast, blood, primary, relapsed, metastatic and drug-resistant cancers with expert bioinformatics support to maximise its utility. The proposed infrastructural enablers include enhanced resources to support clinically relevant in vitro and in vivo tumour models; improved access to appropriate, fully annotated clinical samples; extended biomarker discovery, validation and standardisation; and facilitated cross-discipline working. ConclusionsWith resources to conduct further high-quality targeted research focusing on the gaps identified, increased knowledge translating into improved clinical care should be achievable within five years
Estudo comparativo da celularidade da reação inflamatória aguda na serosa e mesentério intestinais às telas de poliamida e polipropileno em ratos wistar com peritonite fecal por técnica morfométrica
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-graduação em Ciências Médicas, Florianópolis, 2004A peritoneostomia é um recurso tático na condução de pacientes com peritonite aguda grave e com síndrome compartimental abdominal. Diversas próteses são utilizadas no fechamento temporário da cavidade, como o tule de poliamida, porém com pouca citação na literatura. Os estudos com próteses na cavidade abdominal freqüentemente são dirigidos à resposta inflamatória crônica e como nas peritoneostomias estas são retiradas em até 48 horas, outros sobre a resposta aguda são necessários. O polipropileno é a tela freqüentemente utilizada, entretanto, com custo elevado. Objetivo. Estudar a reação inflamatória aguda, sob a ótica morfométrica, da serosa e mesentério intestinais às telas de poliamida e polipropileno em ratos Wistar com peritonite fecal. Métodos. Foram utilizados 67 ratos Wistar distribuídos em 3 grupos: 1 controle, 1 sham e 1 experimento. Os do grupo experimento foram distribuídos em subgrupos, experimento polipropileno (Epp # com peritonite e tela de polipropileno) e experimento poliamida (Epa # com peritonite e tela de poliamida). A reação inflamatória celular aguda foi estudada na serosa intestinal e mesentério dos animais com tela e no grupo sham. Foram utilizados os testes de Kruskal-Wallis para comparações múltiplas e o método de Dunn para comparação pareada dos dados. A hipótese nula foi rejeitada com nível de significância de 5% (p < 0,05). Resultados. Não houve diferença na resposta celular nos animais dos grupos Epp e Epa. Conclusão. Não houve diferença na resposta celular nos animais dos grupos Epp e Epa. A peritonite foi a principal responsável pela resposta celular inflamatória aguda encontrada.Laparostomy constitutes in important strategy in the management of patients with severe acute peritonitis and compartmental abdominal syndrome. Prosthetic materials are used to close the abdominal cavity temporally and the polyamide has been little mention in medical literature. Researches are about chronic inflammatory response. However in laparostomy the prosthesis is removed until 48 hours after the last procedure and research about acute inflammatory response are necessary. Polypropylene mesh is habitually used but it is expensive. Objective. To study the acute cellular inflammatory reaction, under morphometric evaluation, of serosa and mesentery intestinal in contact with polyamide and polypropylene mesh in Wistar rats with fecal peritonitis. Methods. Sixty-seven Wistar rats were used distributed in 3 groups: 1 control, 1 sham and 1 experimental. The experimental group was distributed polypropylene - Ppe (acute peritonitis and polypropylene mesh) and polyamide experimental # Pae (acute peritonitis and polyamide mesh). The acute cellular inflammatory response was studied in the intestinal serosa and mesenteric tissue in contact with meshes in both groups with acute peritonitis and mesh. Statistical evaluation was done by Kruskal-Wallis test for multiple comparison procedures and Dunn#s method for pair comparison procedures. The null hypothesis was rejected at the 5% significance level (p< 0,05). Results. There was no difference in cellular response in animals of Ppe and Pae groups. Conclusion. Data allows conclude that there is no difference in cellular response in Ppe and Pae groups and the acute peritonitis was responsible by acute cellular inflammatory response in the current research
The popular politics of the poll tax: An active citizenship of the left?
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 19/10/2000.The Community Charge (poll tax) was seen by both its supporters and opponents alike as an attempt to promote the British New Right's concept of responsible active citizenship in local politics. The reaction of different groups of citizens to the tax is explored through a detailed case study of events in the London Borough of Ealing, an archetypal London suburb. Here, as in most urban areas, organised anti-poll tax protestors clashed with MPs, councillors and the local magistracy, who played a large role in enforcing the measure. It shows how the protestors attempted to mobilise a 'moral community' built around the idea of 'fair' taxation and promote a campaign of civil disobedience to force abolition. This in turn compelled local actors to make principled choices about the enforcement of a law of which many of them strongly disapproved. The protestors' tactics seemed to strike a popular chord and at least a fifth of all Ealing charge-payers (and eight million people nationally) failed to pay the tax in 1990/91. However, the detailed evidence also suggests that non-payment can best be seen as a mass expression of bloody mindedness, rather than a concerted and organised campaign of civil disobedience. Nevertheless the protests had important implications for the practise of left-wing citizenship in contemporary Britain and served to highlight growing divisions between the mainstream and radical Left. Previously published academic accounts have addressed the 'high' politics of the poll tax. The thesis explores instead the 'popular' politics of the poll tax crisis in a suitably local setting and so redresses an imbalance in the literature. It therefore makes an original contribution to knowledge and understanding of the relationship between conventional means of political participation, radical popular protest movements and competing concepts of citizenship
