Marfan Syndrome is a genetic, cardiovascular disease caused by a defect in the fibrillin 1 gene on chromosome 15. This defect causes abnormal deposition of elastin throughout the body. Elastin is found in many organs including the aorta. Marfan Syndrome is diagnosed by the Ghent criteria. The mean age at death is 44 years for men and 47 years for women, and about 70% die from acute cardiovascular complications, mainly aortic dissection. The assessment and treatment of the aortic complications of Marfan Syndrome has not changed for many years. Serial echocardiography is performed to measure the aortic root diameter. If thought to be increasing in size, beta blockers are prescribed to delay aortic dilatation and surgery, and to prevent aortic dissection or rupture despite the paucity of good research data. I have investigated three novel diagnostic tools: Tissue Doppler Imaging, Applanation Tonometry and Wave Intensity Analysis which have potential advantages in the assessment of the left ventricle and aorta and their interaction in Marfan Syndrome. I also investigated three drugs a beta blocker, an angiotensin converting enzyme inhibitor and a calcium channel blocker to look at their impact on some of the parameters measured by these three novel tools in a double-blinded, randomised cross-over trial. I conclude that these three novel tools would be useful adjuncts in monitoring Marfan Syndrome and their response to treatment. I also found that beta blockers may still have a role to play in delaying and preventing aortic complications when given together with an angiotensin converting enzyme inhibitor, calcium channel blocker or angiotensin receptor blocker. There are, however, other issues that need addressing to improve the management of the cardiovascular complications of Marfan Syndrome. This includes a multi-team approach to this multi-system disease and improvements in the standard of research.

P2Y12 antagonists are pharmacological agents used clinically in advanced stages of coronary artery disease in order to inhibit ADP-induced activation and aggregation of platelets and prevent deadly thrombotic events. Of the orally-prescribed P2Y12 antagonists available clopidogrel is the most established, it exhibits an excellent safety track record and is a popular drug, and was accredited for years the second-best selling drug in the world. However, since clopidogrel was introduced to the market in 1997 many pleiotropic effects have been noticed, which suggest other off-target yet beneficial effects in addition to its anti-platelet effects. The overall hypothesis being tested in this body of work was that P2Y12 antagonists, clopidogrel in particular, have the positive influence on vascular NO signalling. A vascular model was set up using isolated rabbit aortae in which clopidogrel enhanced NO donor-induced vasorelaxation. Although the precise mechanism was not found, the effect was independent of P2Y12 receptors and possibly linked to decreased superoxide production and improved anti-oxidant/inflammatory status in vessels. This finding might be relevant for patients receiving concomitant therapy with organic nitrates and clopidogrel. In vitro studies revealed novel S-nitrosation properties of P2Y12 antagonists, surprisingly without the need for metabolism to their active form. Newly synthesized SNO derivatives of clopidogrel and prasugrel were more potent in inhibition of platelet aggregation and induction of vasodilation than their parental forms. Although the formation of drug-SNO species has to be confirmed in vivo, they have a potential to increase NO bioavailability in patients. Clopidogrel administration to coronary artery disease patients resulted in upregulated plasma levels of nitrite and cGMP after 2 h-intake of a loading dose, which were further increased after 3 days of a maintenance therapy. This effect was never shown before in man and most likely reflects improved endogenous NO production, but also providing additional protection from the effects of nitrite at the same time. Taken together, the results of this thesis clearly demonstrate the influence of clopidogrel on vascular response to NO as well as NO production, metabolism and bioavailability. It is important to identify these alternative pathways especially in the current era with alternative P2Y12 antagonists that overcome some of the limitations of clopidogrel but may not share all the beneficial properties.

Neutrophils are phagocytic white blood cells which act as the first line of defence against entry of foreign microorganisms. Neutrophils are recruited to their target site through the process of spreading, extravasation and phagocytosis involving complex signal transduction within the cells, which might include the activation of the cytosolic Ca2+ activated protease, calpain-1. The work described here investigates the role of calpain-1 in regulating neutrophil functions such as spreading, trans-endothelial migration, chemotaxis, phagocytosis and Ca2+ signalling. Through the work done at European Mutant Mouse Archive (EMMA), Oxford, and by using intracellular sperm injection (ICSI) of calpain-1 deleted gene from mice generated in the USA, and with a selective genotype breeding programme, a colony of homozygous calpain-1 KO mouse has been generated in Cardiff. Homozygous calpain-1 KO neutrophils appeared to have a smaller surface spreading area and their recruitment into the peritoneal cavity of the mouse in vivo was disrupted. In vitro experiments showed significant defects in their ability to cross the ICAM-1 expressing endothelial cells in trans-endothelial migration assay. Disruption in this transmigration was only evident with ICAM-1 upregulated (TNF-treated) endothelial cells, suggesting a specific defect in the β2 integrin-ICAM-1 signalling process. Calpain-1 absence did not affect signal transduction as neutrophils were able to signal cytosolic Ca2+ in response to β2 integrin engagement (C3bi-opsonised zymosan) and also to release intracellular Ca2+ store upon IP3 uncaging. This showed that the IP3 pathway in the cells was not affected by knocking-out calpain-1 and continued to be functional. The key signalling mechanisms from β2 integrin also remained intact and this is consistent with calpain-1 activation by Ca2+ being an important event in trans-endothelial migration. In conclusion, calpain-1 absence has significantly affected the ability of neutrophils to undergo trans-endothelial migration and this effect is directed towards the event which happens downstream to the increase in cytosolic free Ca2+ concentration.

Investigations into the function of mesenchymal-TG2 in epidermal formation and keratinocytes migration were established with varying success using coculture systems. Results indicate TG2 overexpression increases the rate of keratinocytes migration via an as yet unidentified soluble factor. Conversely, the presence of fibroblasts overexpressing this TG have demonstrated an inhibitory effect on keratinocyte migration.

There has been an ongoing debate regarding appropriate strategies for the management of carious primary teeth. Studies appear to provide evidence that both selective, symptom-based interventions and traditional restorative strategies are advantageous. However, the analysis and quantification of childhood caries may be affected by clustering of data, and the concurrent risk of exfoliation of primary teeth. Multilevel generalised linear models for the occurrence of primary caries were derived utilising data from a cohort study of 2,654 children aged 4-5 years at baseline undertaken 1999-2003. These models, which assumed underlying hierarchies with clustering at child, tooth and surface levels, identified higher rates of caries occurrence in primary molar teeth to be associated with boys, poor socio-economic background, lack of water fluoridation, 2nd mandibular molars and occlusal surfaces. Significant risk factors identified were carried forward for inclusion in parametric competing risks multivariate multilevel survival models, utilising cohort study data augmented with Dental Practice Board treatment data. Analysis of sound teeth and surfaces found the concurrent risk of exfoliation did not alter inferences of parameter significance, but restricted the extent of caries occurrence and reduced distinction in survival experience between different types of teeth and surfaces in children from different demographic backgrounds. Further competing risks survival models were derived to analyse the same teeth and surfaces in the untreated carious and filled states, to assess the effect of restorative treatment on subsequent exfoliation and extraction. Survival rates extrapolated to 14 years without further treatment for filled molar teeth were approximately double those of untreated teeth. Time of caries occurrence and treatment also affected survival, with later occurrence or treatment of caries associated with higher survival rates. However, early filling of carious teeth resulted in the greatest reductions in the expected time that decay is present in the mouth.

Investigations have been made into the use of a computer based simulation technique (Monte Carlo (MC)) to ionising radiation transport in order to verify the doses delivered during linear accelerator based stereotactic radiotherapy and radiosurgery. Due to the complex nature of the micro multi-leaf collimators (μMLC) used in this these treatments, a bespoke model of the μMLC was developed and combined with standard component modules to represent the remainder of the linear accelerator. Following validation of the above models, investigations were made into the dosimetry of small fields, defined by the μMLC and measured with a variety of detectors. Comparisons of relative output, profiles and depth doses were made against MC simulations, and a series of correction factors determined, to account for detector geometry and the non water equivalence of materials used in semiconductor detectors. An assessment was then made to determine the smallest fields that can be measured with each detector with confidence. Systems were then developed to independently simulate stereotactic treatments and compare doses simulated with those calculated by the treatment planning system (TPS); excellent agreement between TPS calculations and MC simulations was observed. The application of MC methods to determine the most appropriate treatment tactics and calculation algorithms for stereotactic body radiotherapy in the lung was then investigated with recommendations made on the most appropriate calculation algorithms and beam arrangements for the technique. The doses calculated using the type-b or collapsed cone algorithm agreed most closely with the MC simulation. There was little difference observed between plans using more than four beams in the treatment delivery. Treatment techniques using only three beams or less achieved poorer coverage of the tumour with dose, producing lower doses at the periphery of the tumour near the interface with the surrounding lung tissue, compared to using a greater number of beams. Finally, methods of transit dosimetry using Electronic Portal Imaging Devices were investigated for use in cranial stereotactic radiotherapy. Three methods were investigated based on a full MC simulation of the radiation transport through the patient and on to the imager, prediction of the dose based on a TPS calculation and an approximation of the radiological path length of the central axis of the beams to derive an expected dose at the imager plane. The MC method produced the best agreement at the expense of a longer time to acquire the comparison doses compared to the TPS calculation method. The equivalent path length method showed good agreement (within 3.5%) between delivered and predicted doses but at a single point.

Vγ9Vδ2 T cells are a minor subset of T cells in human blood that differ from all other lymphocytes by their specific responsiveness to (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP), a metabolite produced by a large range of microbial pathogens. Vγ9Vδ2 T cells can be skewed towards distinct effector functions, in analogy to, and beyond, the emerging plasticity of CD4+ T cells. Depending on the microenvironment, Vγ9Vδ2 T cells can assume features reminiscent of Th1, Th2, Th17 and Treg cells as well as professional antigen presenting cells (APCs). The main focus of this PhD was to investigate the role of the follicular B helper T (Tfh) cell derived cytokine IL-21 in enhancing the ability of human Vγ9Vδ2 T cells in providing B cell help. In order to try to mimic the physiological conditions in the GC, an in vitro system of autologous Vγ9Vδ2 T cells and B cells from tonsils or blood, the microbial metabolite HMB-PP and IL-21 was used. HMB-PP induced up-regulation of IL-21 receptor on Vγ9Vδ2 T cells. In return, IL-21 played a co-stimulatory role in the expression of the B cell-attracting chemokine CXCL13, the CXCL13 receptor CXCR5, the co-stimulatory molecules inducible co-stimulator (ICOS), OX40 and CD70 by activated Vγ9Vδ2 T cells. IL-21 also enhanced the ability of activated Vγ9Vδ2 T cells to support antibody production by B cells. Furthermore, Vγ9Vδ2 T cells not only themselves became highly activated APC marker expressing cells but also modified activation and APC marker expression on B cells. Findings presented in this thesis provide evidence that IL-21 contributes to the acquisition of B cell helper functions by human Vγ9Vδ2 T cells. In secondary lymphoid tissues, the interaction between HMB-PP-responsive Vγ9Vδ2 T cells, IL-21-producing Tfh cells and B cells is likely to impact on the generation of high affinity, class-switched antibodies in microbial infections

Having identified differentially regulated genes, the final and most labour intensive part of the analysis process is drawing biological conclusions and hypothesises about the data. A novel solution is presented which combines experimental data with a curated annotation sources along with analysis tools to assist the researcher in exploring the information contained within their dataset.

This case study has been built on a theoretical basis that recognises the current status of English as an international language, especially its influence on specific domains. The theories underpinning the study generally recognise that the presumed 'superiority' of native speakers can be depreciated, taking into account the huge numbers of non-native speakers worldwide. Specifically, the study has targeted the medical field in Saudi Arabia from a needs analysis perspective, as this domain represents a typical representative milieu where the adopted theories of the language universality and its role as lingua franca can be validated. Interviews and questionnaires were used in a mixed-method approach, to investigate needs, attitudes, and motivations of both medical students and practitioners in their current or prospective situations. Before conducting the research, it was assumed that the researched constructs in presumably two different sites, i.e. academic and professional, would engender different sets of data. Yet, the participants addressed viewpoints appeared to be mostly unanimous. The findings also showed that the increased influx of Saudis in the medical workplaces has minimised the role of English as a communicative means, and English was relegated to specific occupational purposes in such settings. This specific English refers mainly to medical terms, which are mostly code-mixed with Arabic. The study concluded that in this multilingual setting, Arabic has somehow restricted the 'nativisation' of English in the Saudi medical spheres. One of the initial motives of the research was to allow a space for non-native Englishes in the context of the study. However, the study found that the issue of certain variety, whether native or non-native, is at a secondary position to the participants, compared to other prioritised needs. Furthermore, the findings exhibited some issues related to learners’ motivation and language courses failure, which unfolded the expediency of a content-based approach, namely English as a medium of instruction (EMI). More clearly, the participants’ learning experiences revealed the usefulness of EMI in enhancing their proficiency levels, more than language courses can do.

This thesis examines the influence of selected environmental stimuli on spatial and temporal variation in acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Evidence indicates that the high level of humidity in the British climate, and the weather associated with the occurrence of mist and fog, may play an important part in the high incidence rates of asthma and COPD in the UK. Recent studies on this subject area are scarce. The influence of geographical features on pollutant concentrations and variation in meteorological conditions is often acknowledged when examining the effect of air quality and weather on respiratory health, but a thorough investigation is rarely conducted. Focussing on the localities of Worcester and Dudley, this research addresses these deficits by incorporating two main study elements. The first stage examined the variation in daily hospital admissions for asthma and COPD between 1998 and 2003. During the second phase of the study programme, a 12-month daily symptom study was undertaken in a cohort of 52 COPD subjects. The findings from the project demonstrate that relative humidity, temperature and dew point play a significant role in exacerbations of asthma and COPD. The direction of the correlation found for these meteorological variables indicates that their role is of a combined nature, rather than independent of each other, leading to significant changes in respiratory symptoms during weather associated with high levels of airborne water droplets or the formation of mist and fog. The deleterious influence of air pollution on respiratory wellbeing was also confirmed. Particulate matter showed the strongest effect on symptoms in COPD. Particles can serve as nuclei for the formation of airborne water droplets. Enhanced lung retention of droplet borne pollutants, in contrast to dry particles, is possible. Finally, the results from the research provide evidence of increased respiratory symptoms in lower altitude areas of river valleys. The findings show that airflow, humidity and temperature regimes produced in valley regions, by local topographic features, can lead to interaction between meteorological conditions and air pollution that have an adverse effect on respiratory health.