Background - Resistant hypertension (RH) is common among adults with hypertension affecting up to 30% of patients on treatment for blood pressure (BP) control. It is predicted to increase, as old age and obesity are considered major risk factors for RH. Effective treatment of RH still remains an unmet goal of antihypertensive treatment. This thesis compared two methods of treating RH in two hospital settings, with or without the use of a biochemical blood test. Methods and Results - This was a prospective, quantitative cohort study conducted over 20 months. A total of 213 patients were recruited; 109 (100%) from site 1 (SI) and 111 (100%) from site 2 (S2). The mean age was 53.6 for S 1 and 55.1 for S 2 and there were 58 male patients from both sites (SI, 53% v S2, 52%). There were 12.9% v 18.21% smokers, 6.8 % v 15.3% diabetics, 54.1% v 79.3% hypercholesterolaemia and a family history of coronary heart disease 61.1% v 83.3% in SI and S2 respectively. The comparison of BP control between the two groups for the study period showed 30.5% from SI and 32.5% from S2 achieved BP control. A comparison at fixed time of three, six, and nine months SI v S2 (10.5% v 16.2%, 20.0% v 22.2%, 26.3% v 23.2%) showed no statistically significant difference in BP control. Among those aged <55yrs, 29.5% at SI v 36.4% at S2 achieved BP control. Among those aged >55yrs, 22.5% at SI v 34.5% at S2 achieved BP control, Conclusion - There was no statistically significant difference in BP control between those treated on the basis of a biochemical profile or on the nationally agreed algorithm. It can be proposed that health care professionals such as specialist nurses in cardiology could play a significant role in addressing this growing problem.

Ataxia-telagiectasia (A-T) patients exhibit increased sensitivity to ionising radiation and also demonstrate a higher than normal risk of developing cancer. Heterozygote phenotypes exhibit intermediate levels of radiation sensitivity compared to A-T homozygotes and controls and also have an increased risk of cancer, but are asymptomatic. Radiation used in diagnostic procedures could predispose such individuals to the development of cancer. Classically, clinical diagnosis only discriminates between homozygote and non-homozygote individuals, necessitating the development of a routine approach that facilitates identification of A-T heterozygotes. Tissue culture patient derived cell lines, when used in combination with western blot analysis revealed it was possible to identify cell lines with ATM mutations compared to controls, but discrimination of each genotype was not possible using this methodology. Similarly, flow cytometry was used to determine the cell death profiles of the same patient-derived cell lines upon exposure to a variety of cell damaging agents (ionising radiation, chemicals or chemotherapeutic drugs), with the aim of discriminating A-T heterozygotes from homozygotes and controls. This methodology revealed that cell death profiles generated in response to hydrogen peroxide were able to discriminate each of the three genotypes in both lymphoblast and fibroblast cell lineages. In SV40 patient derived lymphoblasts, the increase in late apoptotic cells and the reduction in necrotic cells in the A-T homozygote cells was found to be statistically significant compared to controls. Likewise, the reduction in late apoptotic cells and the increase in necrotic cells in the A-T heterozygote cells was also found to be statistically significant compared to both A-T homozygotes and controls (P <0.05 one-way ANOVA). In untransformed fibroblasts, using a telomerase transformed fibroblast cell line as the control, the increase in early apoptotic cells and total apoptotic cell death (early and late apoptotic cells combined) in the A-T homozygote cells was found to be statistically significant compared to the control. The increase in early apoptotic cells and total apoptotic cell death in the A-T heterozygote cells was also found to be statistically significant compared to both the A-T homozygotes and the control (P <0.05 one-way ANOVA). It was on this basis that a clear distinction could be made between the three genotypes in two different cell lineages in response to hydrogen peroxide treatment. It had previously been reported that virus transformed cell lines produced different cell death profiles to primary or untransformed cell lines from A-T patients and carriers compared to controls following exposure to ionising radiation. Data presented here confirms these observations with additional A-T homozygote, A-T heterozygote and control cell lines in SV40 transformed lymphoblasts and untransformed fibroblasts. Data is also presented using the same patient-derived cell lines with the chemicals hydrogen peroxide and staurosporine, and the anticancer drugs etoposide and bleomycin. The differential response of SV40 transformed cell lines and untransformed cell lines to these treatments calls into question whether virally transformed cell lines should be used to predict in vivo cellular responses.

Abdominal aortic aneurysm (AAA) is a common disorder and a major cause of death. Pathological processes involved in AAA formation include inflammation, proteolysis, angiogenesis and apoptosis. It has also a strong familial predisposition with linkage studies identifying chromosomes 19q13 and 4q31 as susceptible loci. AAA is likely to be a polygenic disorder. Aims The aims of this study were to carry out a whole transcriptome analysis in order to identify novel genes and pathways that are differentially expressed between aneurysmal (AAA), atheromatous (AOD) and normal (NA) aortic tissue and to confirm a set of these differentially expressed genes using quantitative real time polymerase chain reaction (qRT-PCR). Methods RNA samples were prepared from full thickness aortic walls obtained during open repair of AAA, aortic bypass for AOD and transplant patients for NA. The quality of the RNA was assessed using the Bioanalyzer 2100 (Agilent) and Nanodrop. RNA was then reverse transcribed to cDNA which was then hybridised to the Human Genome (HG) -U133 plus 2.0 microarray (Affymetrix) that interrogates the whole human genome. The robustness of the genearray was assessed using data output quality control as defined by Affymetrix. Statistical analysis was then carried out using the GeneSpring software. Genes were considered to be significantly differentiated if they had at least a two-fold change and a P-value &lt; 0.05 following Benjamini-Hochberg multiple correction testing. Genes were then classified according to their molecular functions. A set of consistently differentially expressed genes were confirmed using qRT-PCR with Taqman probes on a larger sample size compared with the microarray experiment. All pathway and network analysis on the differentially expressed genes were conducted using MetaCore software Version 6.3 (GeneGo, Inc). Results A total of 3320 genes and 233 genes were differentially expressed when comparing AAA with NA and AAA with AOD respectively.

Coronary artery disease and coronary microvascular disease, as well as acute myocardial infarction and adverse remodelling are often characterised by tissue hypoxia. They benefit from the earliest possible diagnosis and treatment. Positron Emission Tomography (PET) is a highly sensitive technique capable of non-invasively imaging the biochemistry of the body, with the capacity to track biochemical changes over time. In this project, we aim to characterise a series of novel PET imaging agents able to identify and characterise hypoxic myocardium with a view to optimising the treatment of a range of cardiovascular diseases. Bisthiosemicarbazone (BTSC) ligands readily chelate positron emitting copper isotopes, and have been demonstrated to selectively accumulate in hypoxic tissue in vitro, in vivo, and in isolated perfused hearts. While the lead compound Cu-ATSM has been widely investigated, a library of related Cu-BTSC complexes exist which may have better pharmacokinetics and selectivity for application in cardiology. We employed isolated ventricular myocytes and isolated perfused hearts to screen a number of 64Cu-labelled BTSC complexes, to assess their hypoxia selectivity and accumulation in cardiac tissue. For this purpose we developed a novel incubation chamber for maintaining isolated cardiomyocytes under hypoxic conditions. We also developed a novel gamma radiation detector array comprising three Na/1 y-detectors, for monitoring the flow of radioactivity through isolated perfused hearts in real-time. We have demonstrated the hypoxia selective accumulation of 6 Cu-ATSM in adult rat ventricular myocytes (ARVM) incubated under hypoxic conditions. Using isolated perfused hearts we demonstrated that all 64Cu-BTSC readily accumulate within cardiac tissue in an oxygen-dependent manner. We have demonstrated the hypoxia selective accumulation of 64Cu-ATSM in adult rat ventricular myocytes (ARVM) incubated under hypoxic conditions. Using isolated perfused hearts we demonstrated that all 64Cu-BTSC readily accumulate within cardiac tissue in an oxygen-dependent manner. We also identified a relationship between the structure of Cu-BTSCs and their tissue retention, with lower molecular weight complexes providing the greatest hypoxic to oxygenated tissue contrast. In doing this we have identified two complexes, Cu-ATS and Cu-CTS, which could potentially supersede Cu-ATSM as the agent of choice for imaging the hypoxic myocardium.

Cardiac Resynchronisation therapy (CRT) is an established treatment for heart failure patients with severe left ventricular (LV) dysfunction and widened QRS duration. Response to CRT remains variable. Up to 30% of patients do not gain symptomatic benefit with numbers that fail to reverse remodel (RR) even higher. Strategies to improve response rates have focused on pre-implant dyssynchrony following assumption that electrical dyssynchrony translates into mechanical dyssynchrony. Other factors that influence outcome are presence of myocardial scar and LV lead position. Cardiac magnetic resonance (CMR) imaging can quantify global myocardial dyssynchrony in different modalities; volume change, muscle thickening and strain. Understanding how these measures of dyssynchrony relate to each other is important when considering how they can assist patient selection. In addition the role of CMR to assess cardiac anatomy and scar means that it is ideally placed as an imaging modality to provide comprehensive evaluation of heart failure patients prior to CRT. This thesis aims to explore the feasibility of using CMR imaging as an inclusive imaging method to assess patients for CRT. Forty-eight patients fulfilling the criteria for CRT were recruited (43 male, 63.8±13.9 years). 25 had dilated cardiomyopathy (DCM) and 23 ischaemic cardiomyopathy (ICM). All patients underwent a CMR and echocardiographic.

This thesis evaluates the role of cardiac magnetic resonance (CMR) imaging in the assessment of patients with surgically repaired Tetralogy of Fallot (TOF). CMR has become a powerful tool in the serial assessment of this group of patients and provides important information on cardiac structure and function long after surgical repair. Although there are a number of long-term effects of TOF repair, chronic severe pulmonary regurgitation (PR) continues to be considered one of the most important as this has detrimental effects on cardiac function with a risk of sudden cardiac death. The optimal timing of pulmonary valve replacement remains controversial and although CMR has provided valuable information on the volumetric changes associated with chronic PR little is know about the effects of stress with pharmacological agents such as dobutamine on ventricular function and whether this can be correlated with the need for pulmonary valve intervention. Therefore, the main aim of this thesis was to determine whether dobutamine stress CMR (DS-MR) has clinical utility in TOF patients with significant PR. Through this, it has been possible to evaluate the hemodynamic and volumetric changes during DS-MR in TOF patients and how these relate to baseline characteristics. The association between great artery flow analysis and volumetric analysis in TOF patients during DS-MR has also been assessed. For comparison the DS-MR protocol was also completed in a group of healthy volunteers and this has allowed documentation of a normal volumetric and contractile reserve response to dobutamine as measured by CMR. The thesis concludes that DS-MR is safe and feasible in TOF patients and that it has potential to demonstrate early systolic ventricular impairment in these patients. Through application of DS-MR in a larger population of TOF patients it may be possible to accurately determine which patients are best suited for early pulmonary valve intervention.

Hypertension is the number one killer in the Western world at present and is a major risk factor for the development of cardiovascular disease. However, despite the extensive range of therapies, the mechanisms involved in its onset still remain unclear, therefore there is a need to investigate the mechanisms involved. Calcitonin gene-related peptide (CGRP) is best known as a sensory nerve-derived neuropeptide, a potent microvascular vasodilator and is suggested to be protective in a range of models of hypertension. The aim of this study was to investigate the influence of CGRP on vascular mechanisms in an Angiotensin-ll (Ang II) model of hypertension. Wildtype (WT) and aCGRP knockout (aCGRP KO) mice were infused with either vehicle (saline) or Ang II for 14 (1.1mg/kg/day) or 28 (0.9mg/kg/day) days. Under both normal physiological conditions and after saline infusion, blood pressure (BP) and gross pathological observations did not differ between WT and aCGRP KO mice. Ang II infusion caused an increase in BP in the mild-moderate hypertensive range in WT mice at both 14 and 28 days. However in the absence of aCGRP, this hypertension was exacerbated, this being in the moderate hypertensive range at day 14, and becoming severely hypertensive by day 28. When measuring CGRP levels, plasma and mRNA aCGRP expression was upregulated in the aorta and mesenteric vessels of hypertensive WTs, and localisation of CGRP (a and (3) was visible in endothelial and smooth muscle cells of the aorta. This increase in CGRP expression was also accompanied by an increase in CGRP receptor expression at day 28 in WTs. Vascular inflammation/remodelling of the aorta was apparent in the developing hypertension, perhaps via the loss of endothelial derived nitric oxide synthase (eNOS) and a resultant increase in NADPH oxidase. This inflammation/remodelling was characterised by increased luminal wall width, collagen expression and cytokines/adhesion molecules.

The two regulatory RIα subunits of cAMP-dependent protein kinase (PKA) form interprotein disulfides during oxidative stress which is associated with kinase activation. PKA classical activation involves cAMP binding to the regulatory subunits causing release of catalytic subunits which phosphorylate substrates. Presence of substrate sensitises Type I PKA to cAMP. PKA subcellular localisation is determined by regulatory subunits binding A-kinase anchoring proteins (AKAPs), with RIα oxidation enhancing their binding. I assessed whether thioredoxin (Trx) redox recycles disulfide RIα back to its reduced state. In adult rat ventricular myocytes (ARVMs) pre-treatment with diamide (inducing disulfide) potentiated isoprenaline-induced cardiac Troponin I phosphorylation. Inhibition of monoamine oxidase (MAO), which metabolises monoamines to generate hydrogen peroxide (H2O2), blocked monoamine-induced RIα oxidation. Echocardiography revealed that RIαCys17Ser „redox-dead‟ knock-in (KI) mouse (which I verified cannot form disulfides) hearts had larger left ventricles during diastole and systole and demonstrated systolic dysfunction. Cytosolic RIα disulfide translocated to membrane and myofilament in isolated WT hearts in response to oxidant. Dual-specificity AKAP (D-AKAP) 1, D-AKAP2, AKAP220 and α/β tubulin were not co-purified with WT or KI RIα after cAMP-affinity capture. LC-MS/MS showed that the PKA substrates, alpha-enolase and ChChd3 did co-purify, but the AKAPs associated with these (myomegalin and sphingosine kinase interacting protein, respectively) were not co-captured. Trx recycled disulfide RIα back to its reduced state shown by an RIα-dependent decrease in NADPH fluorescence and RIα disulfide accumulation in ARVMs treated with Trx reductase inhibitors. In conclusion, whilst monoamines classically elevate cAMP to activate PKA, their degradation by MAO generates H2O2 which induces disulfide formation. Disulfide RI translocates from cytosol to membrane and myofilament in response to oxidant, but whether this is due to an increased affinity for AKAPs remains unclear. Disulfide-induced sensitisation of PKA to cAMP is consistent with the idea it increases RIα affinity for AKAPs, so targeting PKA close to substrate to enable substrate-induced activation.

Deep vein thrombosis (DVT) is a common condition affecting 1-2% of the population. It can be further complicated by serious sequelae such as life threatening pulmonary embolus and the chronically debilitating post-thrombotic syndrome. The main treatment modalities available for DVT are only able to limit disease progression, with resolution occurring physiologically. Natural resolution of DVT occurs through a process of thrombus retraction and recanalisation which is comparable to progenitor mediated neovascularisation. The focus of this project was to examine the circulating progenitor cell response to venous thrombosis and to profile the underlying cytokine response. This data was ultimately used, to manipulate the number of circulating progenitor cells and expression of cytokines to enhance the recanalisation process. The presence of venous thrombus produced a bimodal circulating haematopoietic progenitor cell response whilst in the bone marrow compartment progenitor cells were simultaneously depleted. GCSF, GMCSF, VEGF, PIGF and SDF1 were expressed differentially in thrombus, vein wall and plasma, with the laparotomy wound mirroring the cytokine profile of the resolving thrombus. The expression pattern of PIGF in the resolving thrombus was however, unusually specific and not seen in the healing laparotomy wound.

Introduction: Pre-hospital delay (onset of symptoms to hospital arrival) has a significant impact on patients’ mortality and morbidity in myocardial infarction (MI). Many factors have been implicated in patients’ decision to seek care in MI, but most research has a Western origin and it is possible that the reasons for delay differ in Arab cultures. This study aimed to explore the factors that contribute to pre-hospital delay among MI patients in Saudi Arabia. It combined quantitative and qualitative methods using sequential explanatory design. Ethical approval was provided by University of Ulster. Method: This cross sectional study comprised a consecutive sample of research participants (n=311), who presented with a diagnosis of MI to 3 hospitals in Riyadh, from March 2011 to August 2011. Of these, 189 patients met the eligibility criteria and provided quantitative data. A further 18 patients were purposefully selected for semi-structured interviews that were taped and transcribed verbatim prior to thematic analysis. Findings: The median pre-hospital delay for males was 5 hours and for females it was 12.9 hours. A standard multiple regression determined female gender as the strongest predictor of transfer delay in this sample. Lack of knowledge and Control was the core theme in the thematic content interview analysis and it was evident that cultural issues such as wishing to seek permission to attend hospital from a male relative and inability to travel to hospital without a male escort contributed to female patients’ pre-hospital delay.Conclusion: Women’s pre-hospital delay was more than twice that of their male counterparts and the total pre-hospital delay time reported here for both genders is longer than in studies in other settings. Qualitative data indicate that cultural factors are implicated in the prolonged delay experienced by females. Further research to test the generalizability of these findings and to determine any potential impact on female mortality and morbidity for MI is needed. Primary and secondary prevention strategies for potential MI patients in Saudi should consider offering culturally- specific, gender related messages.