Unresolved complex mixtures of aromatic hydrocarbons in the marine environment : toxicity, solubility and photodegradation studies

Merged with duplicate record (10026.1/699) on 03.01.2017 by CS (TIS)This is a digitised version of a thesis that was deposited in the University Library. If you are the author please contact PEARL Admin ([email protected]) to discuss options.Unresolved complex mixtures (UCMs) of aromatic hydrocarbons have been found in a wide range of environmental matrices at high concentrations. However, limited consideration has been given to the potential detrimental effects of the accumulation of these compounds in the marine environment. In particular, there is a need to evaluate these compounds in the light of recent evidence that points to the long term effects of oil in the marine environment. The overall aim of this work was therefore to investigate unresolved complex mixtures of aromatic hydrocarbons in the marine environment with particular emphasis on assessment of toxicity, aqueous solubility and photodegradation behaviour. A previously established link between the reduced Scope for Growth (SFG) of mussels with the concentration of 2-3 ringed aromatic hydrocarbons in mussels from petroleum impacted sites was found also to correlate well with concentrations of aromatic hydrocarbon UCMs in mussel tissues found at the same sites. This suggests that aromatic hydrocarbon UCMs or components within may be responsible for the observed effects. To determine whether an aromatic hydrocarbon UCM was capable of eliciting a toxic response in mussels, a monoaromatic UCM was isolated from a Gullfaks (North Sea) produced crude oil. At the highest nominal aqueous concentration tested, mussel feeding rate was reduced by -40 % in the 24 hour exposure period, during which the mussels accumulated a body burden similar to the body burden of monoaromatic UCM hydrocarbons in wild mussel populations, previously shown to exhibit reduced SFG. Recent studies of hydrocarbon UCM composition using chemical degradation methods have led to the proposition of alkylcyclohexyltetralins as `average' structures for some monoaromatic UCM hydrocarbons. The aromatic hydrocarbon 7-cyclohexyl-lmethyltetralin was synthesised herein in good yield and purity. This compound reduced mussel feeding rate by 50% during the 24-hour exposure period. The aqueous solubility of a compound is an important physicochemical parameter that influences behaviour within the marine environment and is thought to be a limiting factor in the onset of measurable toxicological response. The aqueous solubilities of three `model' aromatic UCM hydrocarbons were determined in distilled water at 25°C using a generator column set-up. The effects of salinity and temperature on aqueous solubility were also investigated. An aqueous solution comprising an aromatic UCM was also generated. Another influence on the fate of aromatic hydrocarbons in the environment is the action of sunlight (phototransformation). Therefore aqueous solutions of three model aromatic UCM hydrocarbons were exposed to light simulated under environmental conditions. The halflives of these compounds suggested that if these compounds are indeed representative of the aromatic UCM phototransformation may influence its fate in the marine environment. The results of this study have furthered knowledge on the environmental behaviour of unresolved aromatic hydrocarbons, and suggest that these compounds should be considered in the long term impacts of oil in the environment and also warrant further study. Parts of this work have been published and the author (Smith, E. L. ) was awarded the Procter and Gamble Eurorcar prize at the 3`d World Congress of the Society of Environmental Toxicology and Chemistry, 21-25 May 2000, Brighton, for the best presentation by a young scientist.the University of Plymouth in collaboration with Plymouth Marine Laborator

Functional characterisation of human CD4+CD25+ regulatory T cells and the transcriptional regulator, FOXP3

Naturally occurring CD4+CD25+ regulatory T cells are thought to play an essential role in the maintenance of immunological self-tolerance by actively suppressing auto reactive T lymphocytes. Exploitation of these cells could provide novel and effective therapies for the treatment of various clinical diseases, including autoimmune diseases and cancer. However the biology surrounding these cells is complex and there are many unresolved issues, including a lack of specific markers for these cells and an incomplete understanding of the mechanism of action of these cells. The initial experiments described in this thesis attempted to identify cell surface markers that were specific to the human CD4+CD25+ regulatory T cell population. Functional assays were conducted in parallel in an attempt to identify cell surface molecules and cytokines that might be responsible for the cell-mediated suppression. The lack of identification of a specific molecule responsible for the suppressor phenotype highlights the complexity of this cell population. As these studies progressed, a new marker of CD4+CD25+ regulatory T cells was reported called FOXP3. Subsequent experiments described in these studies focussed on investigating the effects of overexpressing human FOXP3 in human T cells. A novel cotransfection system was devised whereby the gene encoding FOXP3 was cotransfected with DNA encoding a specific receptor involved in T-cell activation (chimeric receptor). The data generated showed that overexpression of FOXP3 in resting human CD4+ and CD8+ T cells resulted in a significant inhibition of subsequent T cell activation. Splice variant forms of the FOXP3 protein were also investigated and were shown to possess potent repressor activity

Characterizing the Catalytic Action of μ-Calpain on Myofibrillar Protein Structure

Solving the problem of inconsistent meat tenderness is a top priority of the meat industry. This requires a greater understanding of the processes that affect meat tenderness and the adoption of such information by the meat industry. It is essential that we understand the mechanism of meat tenderisation of which, the calpain protease system is believed to play a central role. This thesis focuses on three aspects; characterisation of calpain activity, the effect of porcine μ-calpain on myofibril degradation and the effect of μ-calpain on specific proteins desmin and troponin-T. To study the effect of calpain activity, fluorogenic assays were used to determine: μ-calpain concentration for optimal peptide cleavage; calcium requirements and the effect of chelating substances on the activity of μ-calpain. In addition, the affinity of μ-calpain for substrates CalS-I and CalS-III were assessed. The effect of μ-calpain on myofibril degradation was evaluated through the use of myofibrillar fragmentation index and density marker beads. Myofibrils were digested at three different temperatures for varying time periods. Conflicting results were displayed and it was concluded that these methods are not accurate, thus further research should be conducted to ensure inconsistencies are eliminated. Specific proteins desmin and troponin-T have previously been shown to exhibit degradation in the presence of calcium and μ-calpain. SDS-polyacrylamide electrophoresis, western blotting and densitometry measurements were utilized to investigate this effect. It was concluded that μ-calpain plays a significant role in the post mortem proteolysis of myofibrillar protein. This thesis provides information and strives to give a better understanding of the proteolytic changes that occur within muscle. Understanding how these mechanisms affect meat on a cellular level, can help to control the influence they inflict on meat quality

Using a community-engaged research (CEnR) approach to develop and pilot a photo grid method to gain insights into early child health and development in a socio-economic disadvantaged community

Background The aim of this research was to consult with professionals and parents to develop a new research toolkit (Photo Grid), to understand community assets and priorities in relation to early child health and development in Blackpool, a socio-economic disadvantaged community. A Community–Engaged Research (CEnR) approach was used to consult with community members. This paper describes the process of using a CEnR approach in developing a Photo Grid toolkit. Methods A phased CEnR approach was used to design, test and pilot a Photo Grid tool. Members of the Blackpool community; parents with children aged 0–4 years, health professionals, members of the early year’s workforce, and community development workers were involved in the development of the research tool at various stages. They were recruited opportunistically via a venuebased time-space sampling method. In total, 213 parents and 18 professionals engaged in the research process. Results Using a CEnR approach allowed effective engagement with the local community and professionals, evidence by high levels of engagement throughout the development process. This approach improved the acceptability and usability of the resulting Photo Grid toolkit. Community members found the method accessible, engaging, useful, and thought provoking. Conclusions The Photo Grid toolkit was seen by community members as accessible, engaging, useful and thought provoking in an area of high social deprivation, complex problems, and low literacy. The Photo Grid is an adaptable tool which can be used in other areas of socio-economic disadvantage to engage with the community to understand a wide variety of complex topics

Investigating the role of NF-κB p50 serine 80 phosphorylation in the regulation of inflammation

NF-κB is a key transcription factor involved in the regulation of inflammation. The transcriptional activity of NF-κB is regulated by a number of post-translational modifications, including phosphorylation. Phosphorylation of NF-κB subunits may regulate transcription in a gene selective manner. The NF-κB p50 subunit is an important dual regulator of inflammatory responses, which can either promote or repress gene expression depending on the formation of heterodimer or homodimer complexes, respectively. Although p50 is a critical regulator of the immune system, phosphorylation of this subunit is largely understudied. In this thesis, the role of phosphorylation of NF-κB p50 on serine 80 (S80) in regulating transcriptional responses is investigated, using two human NFKB1S80A knock-in cell lines generated by CRISPR/Cas9 genome editing techniques. Transcriptomic analyses reveal a critical role for S80 in selectively regulating the expression of a subset of NF-κB target genes in response to TNFα and LPS, including pro-inflammatory chemokines and cytokines. DNA binding analyses demonstrate that S80 regulates the binding of p50 to NF-κB binding sites in a sequence-specific manner. Specifically, phosphorylation of S80 reduces the affinity of p50 for κB sites that have an adenine at the -1 position. These data indicate that p50 S80 phosphorylation predominantly regulates transcription through the p50:p65 heterodimer, where S80 phosphorylation acts in trans to limit the NF-κB mediated transcription of pro-inflammatory genes. This advances our understanding of the regulation of transcriptional programmes by the NF-ĸB p50 subunit

Development and characterisation of an ex vivo model system for bone repair

Limitations in current model systems for researching bone repair have hampered the development of alternative clinical therapies. This thesis aimed to develop and validate an ex vivo rat mandible model, to investigate specific molecular and cellular processes involved in bone repair. Maintenance of cell and tissue architecture and viability was shown within mandible slices cultured for up to 21 days, both intact and fractured. Autoradiographic studies showed that resident cells were actively synthesising and secreting proteins, and cells of the osteoblast lineage were shown to survive throughout the culture period. The model was responsive to exogenously added growth factors TGF-p1 and BMP-2, with increased cellular migration / proliferation and expression of bone matrix proteins observed. A second model system, an in vitro bone slab cell culture system, demonstrated that endogenous growth factors could be released from the matrix of bone by chemicals such as EDTA, calcium hydroxide, and sodium hydroxide. Different growth factor release kinetics were observed with each treatment, and released growth factors were capable of actively influencing the behaviour of osteogenic cells. Pre-treatment of mandible slices with these chemical treatments yielded similar results, with an observed increase in cell number, proliferation, and bone matrix protein expression. The ex vivo mandible model developed within this study may represent an ideal system for investigating specific processes of bone repair, as well as a promising alternative to in vivo testing of novel clinical therapeutics.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

What is intended by the term “participation” and what does it mean to people living with dementia? A conceptual overview and directions for future research

Policy continues to emphasise the importance of wellbeing in dementia. However, there is a vital need for psychosocial interventions that can promote positive outcomes to enhance “living well with dementia”. Our developing understanding of what people living with dementia report as being important to them, has resulted in new interpretations of what constitutes wellbeing including constructs such as “growth”, “purpose” and “participation”. These exciting and important constructs are not currently captured by outcome measures within dementia research. This limits our understanding of the value of psychosocial interventions. This paper explores the concept of participation and how continued participation in social life can make a difference to the rights of people living with dementia as citizens. We will firstly consider why participation is important for how we might measure outcomes in dementia research and care. Secondly, we will explore how we might measure participation. Finally, we will consider the value of participation as a psychosocial outcome in future research

Reimagining NSW: four ways to boost community well-being and why it matters

This is part of our Reimagining New South Wales (NSW) series. For this series, vice-chancellors across NSW asked a select group of early and mid-career researchers to envisage new ways to tackle old problems and identify emerging opportunities across the state

Poverty proofing healthcare: A qualitative study of barriers to accessing healthcare for low-income families with children in northern England

Poverty impacts negatively on children’s health and future life chances. Access to the UK’s National Health Service (NHS) is based on clinical need rather than the ability to pay but horizontal inequities in access exist. Children North East, a charity supporting children experiencing poverty, are working with partners to reduce the impacts of poverty on NHS access. This collaborative study aimed to understand barriers to healthcare access faced by families living on low incomes to validate and support further development of a Poverty Proofing© healthcare tool. Twenty-four parents and eight Voluntary Community Social Enterprise sector staff participated in qualitative interviews or focus groups. Data were analysed thematically, and three main themes were identified as impacting access to healthcare: hidden costs, securing appointments and developing relationships with healthcare providers. We conclude that low-income families experience both financial and other barriers to accessing NHS healthcare and that these barriers are exacerbated for low-income families living in remote/rural areas