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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Selective serotonin reuptake inhibitors and tricyclic antidepressants : novel immunomodulating agents

Gordon, Sevelanne January 2012 (has links)
Acute respiratory distress syndrome (ARDS) is an inflammatory disease in humans where no satisfactory therapeutic options exist. Regulation of the immune system by neurotransmitters has been identified as a possible exploitable strategy to treat inflammatory conditions. Antidepressant drugs have been found to have secondary actions including anti-inflammatory activity in a wide range of disease states in vivo. The cellular effects of these drugs that contribute to this effect have yet to be elucidated. The aim was to examine whether anti-depressants have a direct effect on the immune system or an effect on the target tissue such as lung cells. This thesis utilised both primary lung epithelium cells along with the cell lines A549, 16HBE14o- and BETIY02. The macrophage cell line RAW 264.7 was used to determine effects of anti-depressants on immune cells. Mitochondrial function was used as a measure of cell viability while morphological techniques were used to determine levels of apoptosis and necrosis. Cellular cytokine release was used as a determination of inflammation. Nitric oxide production by activated immune cells was measured using the nitrite assay and the expression of inducible nitric oxide synthase measured by Western blot. The BETIY02 cell line was found to have the most similar characteristics to primary lung epithelium cells and could be used as an effective substitute for large-scale screening and mechanistic studies especially in inflammation. Fluoxetine and desipramine reduced the inflammatory signals coming from lung cells exposed to lipopolysaccharide (LPS). In addition to this they proved effective in reducing immune cell activation as evidenced by reduced NO release following LPS exposure via a mechanism of inhibiting iN OS protein expression. Fluoxetine and desipramine exhibited anti-inflammatory effects on both the lung cells and the immune cells, identifying possible therapeutic potential for ARDS.
32

Oral mucosa-nanoparticle interactions and uptake pathways in formulation excipient profiling

Best, Mark January 2014 (has links)
Nanomaterials are generally defined as chemical substances or materials that contain particles with one or more dimensions less tl1an 100 nanometres in size. They may be either engineered or naturally occurring, but have unique properties due to a vastly increased surface area to volume ratio when compared to non-nano (bulk) materials. This provides the potential for the development of a wide range of enhanced formulations with superior efficacy including applications in oral health care .. As the properties of a material change at the nano-scale, there are concerns that the toxicological profile of these materials may also change. Size is only one factor; changes in shape, surface chemistry, chemical composition, porosity and solubility all contribute to the overall biological toxicity profile of a nano-scale ingredient. Established links between the specific properties of a nanomaterial and toxicity are not well understood, leaving an important data gap in the literature. The purpose of this work was to utilise in vitro oral epithelial models for the assessment of safety profiles of nanomaterials for applications in next generation oral care products. Four commercially sourced nanomaterials were analysed, alongside respective bulk counterparts already found within oral care product formulations. These nanomaterials comprised of two nano-zinc oxides (ZnO), silicon dioxide (SiOz), titanium dioxide (TiOz) and hydroxyapatite (Cas(OH)(P04)'). Comprehensive characterisation of each material was carried out using a range of analytical techniques to identify any structure-function relationships in vitro. Initial toxicity screening experiments were conducted using a non-keratinised oral epithelial cell monolayer (H376 cell line) with both cell viability and lysis analysed using MTT and LDH assays respectively. Materials were investigated further using two 3-dimensional tissue models representative of the main tissue types constituting the human oral mucosa: non-keratinised buccal (RHO) and keratinised gingival (GIN-lOO) models. Nanomaterial uptake in the models was investigated using confocal microscopy with a styrl dye (FM 1-43). This led to the development of a novel, high throughput fluorescent assay as a potential method for screening nanoparticle-uptake. Results highlighted the complexities involved with nano-characterisation in biological media using current techniques. A wide variety of particle shapes and sizes were recorded between different nanomaterials, with results being dependent upon the sample preparation steps and specific methods of analyes used. These disparities represent the current challenges experienced by both researchers and regulators of nanotechnology at the present time. ZnO \vas observed to be the most cytotoxic material during monolayer screening, at concentrations exceeding 0.3125% w/v when delivered in protein-free media. Differences between bulk and nanomaterial properties were recorded for all the materials, except for Ti02, but these did not necessarily transfer to effects seen in the more representative 3-D models. Cytotoxicity results from both R1--10 and GIN-lOO models exemplified the disparity between sensitivity of monolayer and the natural stratified tissue structure of human oral mucosa. Keratinised gingival tissue models showed slgnificantly greater durability over the less robust buccal model, in both cytotoxicity assays and IL- lcx cytokine response. Of all materials examined, cellular uptake was only observed for nano-Si02. This was the only material detected trafficking inside the cell using the FM 1-43 styryl dye assay, with confocal data serving to verify the analysis of nanoparticle Internalisation using fluorescence. In conclusion, nanomaterials pose considerable difficulties during formulation and analysis in health care products. The risk of potential uptake and bioaccumulation or translocation to particularly sensitive areas of the body also requires further investigation. Nanomaterials have to be assessed on a case by case basis, and robust/consistent regulatory strategies developed to enable industry to produce and market novel but safe nanoparticle containing formulations. Risks to human health may be less of a hazard when applied to fully functioning healthy human tissue, especially in comparison to existing bulk material effects and current, accepted irritant ingredients (e.g. Sodium lauryl sulphate).
33

Mental health crisis resolution as human occupation : a political and professional discourse

Drury, Dawn January 2014 (has links)
The aim of this thesis is to identify concepts of human occupation within the discourses surrounding Crisis Resolution Home Treatment Teams. The scope of the research covers specific Government policy and research related to the implementation of Crisis Resolution Home Treatment Teams in the United Kingdom, exploring theories of human occupation with the intent of proposing an additional perspective of mental health crisis. Drawing on Michel Foucault's ideas of governmentality and the influences of discourses within historical and political contexts, articles, research reports and government policy have been investigated. Documents reflecting the national context of a number of stakeholders and types of knowledge were subjected to a discourse analysis, mapping the development of mental health crisis as a discursive formation. The main findings in Part One identify how overarching discourses of neo-liberal ideas privileges economic and managerial discursive practices in shaping the remit and measurement of efficacy of this service provision. As a result, these discourses influence the focus of research onto the economic efficacy of Crisis Teams and their role in performing a gatekeeper function to hospital admission. Part Two proposes that concepts of human occupation are implicit within recent Government policy strategies, and posits an additional perspective for exploring how concepts of human occupation manifest themselves in relation to other discourses and through the mode of govern mentality. Links developed between policy rhetoric and service user discourse suggest an additional paradigm for the definition of crisis which draws upon the concepts of human occupation. Future research that can investigate mental health crisis from additional perspectives will address power relations in mental health crisis response and redress the balance of a current economic and managerial research focus in this area. Further investigation from a perspective of occupational disruption/deprivation will contribute to the development of responses to support recovery from mental health crisis, raising awareness of occupation in relation to increasing resilience and well-being. In addition, research exploring concepts of human occupation implicit within a range of social arenas will identify and look to address issues of occupational justice.
34

Advanced stem cell delivery systems for the treatment of corneal epithelial limbal stem cell deficiency

Fok, Elsie January 2014 (has links)
Limbal stem cell deficiency (LSCD) can be treated successfully using ex vivo limbal epithelial stem cells (LESC) derived from cadaveric donor tissue. However, shortages in such tissues and graft rejection, resulting from inflammation, are persistent issues. The purpose of this study was to optimize current culturing techniques used for LESC transplant tissue, considering expansion and cryopreservation issues surrounding the establishment of a stem cell bank. In addition, a novel anti-inflammatory biomimetic peptide was investigated to address issues surrounding amnion and steroid use in LESC transplantation, inflammation and transplant rejection. Cell cultures derived from Optisol and organ culture stored tissues were examined for optimum growth, characterized by an ability to grow to 70 % to 80 % confluence while maintaining epithelial cell morphology and the presence of positive and negative LESC markers (K3, K19, p63 and PAX-6) as identified by immunocytochemical staining and QRT-PCR. Furthermore, the effect of culture expansion and cryopreservation on stem cell characteristics was examined. A short chain IL-l receptor antagonist peptide was synthesized and characterized using mass spectroscopy (MS), high performance liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS). Anti-inflammatory properties were investigated using ELISA detection of IL-8, IL-6 and IL- l ~ in keratocytes and LESC following stimulation with either lipopolysaccharide or recombinant human IL- l~. Feasible delivery of cells and peptide on a contact lens was investigated to assess the possibility of an "all in one" graft. Results showed that organ culture stored tissues can provide 100 % successful cell cultures using current techniques in terms of reaching confluence and maintaining LESC morphology and phenotype. Sub-culturing and cryopreservation of cultures however did not produce confluent cell sheets, as required for clinical application. The anti-inflammatory peptide was shown to effectively suppress production of key inflammatory cytokines in LESC and keratocytes by acting as an IL- l receptor antagonist and interrupting the IL- l inflammatory pathway. Binding of the peptide to the contact lens was shown to be possible. Such a scaffold also supported expansion of LESC. However, the 2.7 nmol of peptide bound to the lens did not significantly lower cytokine production. Findings suggest that it is possible to culture adequate numbers of LESC for the initiation of a stem cell bank using current techniques. However, modifications to culturing methods are needed to ensure successful sub-culturing and cryopreservation. The peptide has been shown to be effective in reducing inflammatory cytokine production, providing a possible alternative to steroids. An a11-in-one graft could provide a key development in treating LSCD. However further work is required to optimize the peptide concentration to allow effective inflammation control.
35

The influence of stent material and diabetes on macrophages trans-differentiation pathways in the progression of in-stent restenosis

Poletti, Tiziano January 2014 (has links)
The outcome of the deployment of cardiovascular stents in coronary arteries compromised by atherosclerosis may be affected by the deposition of a myofibroblast-driven neointimal tissue and consequent re-blockage of the vessel lumen known as instent restenosis (ISR). Its incidence is particularly high in people with diabetes unless drug-eluting stents (DES) are implanted as alternatives to the traditional bare metal stents (BMS) made of stainless steel (ST). However, the long-term outcome of the use of DES is under debate due to evidence of late thrombosis. Monocytes/macrophages (MM) play a key role in ISR participating in the different phases of the host response to the implant. This in-vitro study investigates differences in the distribution and response of MM that may be significant for a better understanding of the causes of the increased ISR occurrence among diabetic patients, particularly focusing on the trans-differentiation potential of MM into myofibroblast-like cells when in contact with ST. The overnight incubation of MM freshly isolated from blood from healthy donors (n=6) in high glucose (4S00mglL) and high free fatty acid (sodium palmitate 0.4mM) concentrations, alone or in combination, aimed at creating a diabetes-mimicking experimental model. MM response to ST seemed exacerbated by the syoergistic effect of the palmitate and glucose as shown by the occurrence of features characteristic of activation as well as by their trend to fuse into the formation of giant cells as shown by scanning electron microscopy. Similarly results from RT-PCR (n=6) suggested an increase in the expression of the mRNA for HAS3, the enzyme responsible for the synthesis of low molecular weight hyaluronic acid characteristic of the inflammatory process. Furthermore, the presence of MM positive for a-actin, as shown by immunocytochemistry, seemed to confirm the occurrence of early changes in their phenotype. This was accompanied by a significant (p<O.OS or p<O.OOS after paired Hest) increase in the release of PDGF-BB, growth factor characterizing the post-inflammatory condition, as well as in the release of 1NF-a confirming the short-term metal-induced inflammatory reaction from MM incubated on ST in comparison to control surfaces as shown by ELISA tests. Flow cytometry on buffy coats collected from three cohorts of donors (control, type 1 and type 2 diabetes) (n=7) suggested that variations among donors with diabetes in the number of circulating activated macrophages and haematopoietic progenitor cells may, once compared to clinical data, help to identify patients at high risk of developing ISR. The hypothesis of the contribution of MM in the deposition of restenotic neointimal tissue through the transformation into myofibroblasts was reinforced by results from flow cytometry that identified, both in freshly isolated buffy coats and after contact with surfaces, subpopulations co-expressing a-actin and markers for MM (CDI4 or CD68). This was also supported by the imununostaining of the cells after overnight incubation on the surfaces where a-actin-positive cells were seen. Furthermore, ELISA test on the supernatants (n=10) suggested that ST triggered a significant increase in the release of PDGF-BB and 1NF-a when compared to control surfaces. This study reinforced the hypothesis that MM can contribute to ISR through phenotypical changes and that the acute synergistic effect of glucose and lipids can affect their level of activation.
36

Cellular mechanisms underlying the cardiovascular toxicity of the highly active anti-retroviral therapy Atripla : efavirenz, emtricitabine and tenofovir

Faltz, Mary January 2013 (has links)
Highly active anti-retroviral therapy (HAART) has proved very successful in reducing the morbidity and mortality associated with HIV infection. This same lifespan prolongation, however, has also revealed many side effects linked to HAART, including cardiovascular disease. A once daily fixed dose drug combination pill Atripla was hoped to improve compliance and adherence. The HAART components of Atripla efavirenz, emtricitabine and tenofovir are considered to be significantly safer than the conventional reverse transcriptase inhibitors but cardiovascular effects of these drugs have yet to be investigated in vitro. The overall objective of this thesis was to examine the effects of the three components of Atripla on cardiovascular cell function.
37

The biomechanical and analgesic effects of lumbar mobilisations

Hebron, Clair January 2014 (has links)
A common treatment used by physiotherapists for patients with low back pain (LBP) is mobilisations. The aim of applying mobilisations is to increase range of movement (ROM) and reduce pain and stiffness. Therapists choose a specific dose of mobilisation for each patient, which includes a decision on the duration of applied force, commonly up to 3 minutes. Little research has been done to determine the biomechanical and analgesic effects of different durations of treatment. There is tentative evidence that increased duration beyond 3 minutes leads to an increase in range of movement and decrease in pain. This research set out to establish the biomechanical and analgesic effects of longer durations of lumbar mobilisations than commonly used in clinical practice. Only the immediate effects of a single treatment dose have been assessed to date.
38

Investigation of host-microbe interactions in the probiotic bacteria Escherichia coli Nissle 1917

Nzakizwanayo, Jonathan January 2014 (has links)
Probiotics are generally live preparations of bacteria that exert beneficial effects on host health when ingested in sufficient quantities. The novel probiotic Escherichia coli strain Nissle 1917 (EcN) has been shown to have a number of beneficial effects in this context, including protection against food-borne pathogens and infectious diarrheal diseases, and maintaining remission of inflammatory bowel diseases by virtue of its anti-inflammatory properties. However, little is known regarding the mechanisms underlying the beneficial effects of this organism. The overall aim of this work was to provide a greater understanding of the mechanisms through which EcN interacts with the mammalian gastro-intestinal epithelium to benefit human health.
39

Novel bioresponsive drug eluting microspheres to enhance chemoembolisation therapy

Ashrafi, Koorosh January 2014 (has links)
Drug eluting beads (DEB) are employed in the treatment of solid hypervascularised malignant tumours by a method called trans-arterial chemoembolisation (TACE). When the microcirculation to a tumour is blocked, oxygen levels decrease to critically low levels causing the tumour to become hypoxic. Hypoxic tumours are known to be chemoresistant and send out growth factor signals leading to angiogenesis and metastasis of tumour cells to other parts of the body. Commercially available DEB are unable to respond to the conditions of hypoxia and will continue to release drug at a constant rate via ionic exchange through the hydrogel. It is therefore recognised that an avenue for improvement would be the development of novel bioresponsive DEB that are able to react to the conditions of hypoxia to overcome chemoresistance associated with the tumour cells.
40

Cardiovascular side effects of the antiretroviral agents rilpivirine, efavirenz, etravirine and abacavir : possible underlying mechanisms

Bergin, Hild January 2014 (has links)
The introduction of highly active antiretroviral therapy (HAART) has dramatically improved the life expectancy of HIV infected individuals. With the increased lifespan, complications associated with HAART are becoming more evident. Together with HIV itself and a higher prevalence of traditional risk factors, the antiretroviral agents are linked to an increase in cardiovascular diseases in the HIV population. In the present in vitro study the direct cardiac effects of a nucleoside reverse transcriptase inhibitor (NRTI) abacavir in combination with palmitic acid or cobalt chloride mimicking a diet high in saturated fatty acids or hypoxia respectively, were studied. Exposure to abacavir has been associated with an increased risk of myocardial infarction in clinical studies, but the damaging molecular mechanism remains elusive. Furthermore the in vitro cardiovascular effects of three non-nucleoside reverse transcriptase inhibitors (NNRTIs) were investigated; first generation NNRTI efavirenz and the second generation NNRTIs rilpivirine and etravirine.

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