No description available.

No description available.

The major focus of the studies described in this thesis is the interaction of lipoproteins and inflammation in vascular diseases. Early studies describe the role of postprandial lipoproteins in the development of lipid-laden macro phages that are a hallmark of atherosclerotic lesions. These studies paved the way for subsequent studies on the role of lipoprotein modification in atherosclerosis. These included the discovery that LDL present in atherosclerotic lesions had properties that were consistent with oxidative modification. To determine whether this modification was a cause or consequence of the disease, studies were performed using antioxidants. These studies defined the effects of antioxidants on early and mature atherosclerotic lesions, as well as on iatrogenic vascular lesions. My laboratory also studied two potential enzymes that have the potential to generate oxidized lipoprotein; myeloperoxidase and 15-lipoxygenase. The effects of pharmacological inhibition and regulation on the latter enzyme were defined. Studies have also addressed the regulation and function of a major receptor for oxidized LDL, class A scavenger receptor. These include regulation, structure-function, and the effects of cell selective overexpression. These lipoprotein modifications have a well characterized role on the infiltration of macro phages and their subsequent engorgement with lipid. Aberrant lipoprotein metabolism may be a factor underlying the recruitment of T Iymphocytes into lesions. Generally, T Iymphocytes have an under appreciated role in the atherogenic process. Studies using mice deficient in Iymphocyte subclasses and specific cytokines are addressing the issue of this cell type in lesion formation. Finally, we have recently discovered a pronounced inflammatory role of angiotensin II that is associated with the development of atherosclerosis and abdominal aortic aneurysms

No description available.

No description available.

The important role played by vascular factors in the pathogenesis of neurodegenerative disease has been increasingly realised over recent years. The nature and impact of ocular and systemic vascular dysfunction in the pathogenesis of comparable neurodegenerative diseases such as glaucoma and Alzheimer’s disease (AD) has however never been fully explored. The aim of this thesis was therefore to investigate the presence of macro- and micro-vascular alterations in both glaucoma and AD and to explore the relationships between these two chronic, slowly progressive neurodegenerative diseases. The principle sections and findings of this work were: 1. Is the eye a window to the brain? Retinal vascular dysfunction in Alzheimer’s disease · Mild newly diagnosed AD patients demonstrated ocular vascular dysfunction, in the form of an altered retinal vascular response to flicker light, which correlated with their degree of cognitive impairment. 2. Ocular and systemic vascular abnormalities in newly diagnosed normal tension glaucoma (NTG) patients · NTG patients demonstrated an altered retinal arterial constriction response to flicker light along with an increased systemic arterial stiffness and carotid artery intima-media thickness (IMT). These findings were not replicated by healthy age matched controls. 3. Ocular vascular dysregulation in AD compares to both POAG and NTG · AD patients demonstrated altered retinal arterial reactivity to flicker light which was comparable to that of POAG patients and altered baseline venous reactivity which was comparable to that of NTG patients. Neither alteration was replicated by healthy controls. 4. POAG and NTG: two separate diseases or one continuous entity? The vascular perspective · POAG and NTG patients demonstrated comparable alterations in nocturnal systolic blood pressure (SBP) variability, ocular perfusion pressure, retinal vascular reactivity, systemic arterial stiffness and carotid IMT. · Nocturnal SBP variability was found to correlate with both retinal artery baseline diameter fluctuation and carotid IMT across the glaucoma groups.

Abstract Background Living, autologous vascular grafts with the ability to remodel , repair and grow may overcome the limitations of contemporary available options. In this thesis we investigate the ability for autologous, tissue engineered pulmonary artery (PA) conduits to remodel and grow in vivo. Methods and Results Vascular grafts fabricated from biodegradable scaffolds were sequentially seeded with autologous vascular derived cells and grown in vitro under biomimetic conditions. These tissue engineered vascular grafts were surgically implanted as main PA replacements in 12 lambs divided into four study groups sacrificed at 20, 50, 80 and 100 weeks post implantation. Transoesophageal echocardiography (TOE) and Computed tomography (CT) angiography was performed in all animals to further assess function and in vivo growth of the tissue engineered PA. Tissue analyses of the conduits were carried out and compared to native tissue over the 2 year study period. The tissue engineered PA showed good functional performance on TOE and CT. There was a significant increase in diameter of the tissue engineered PA of up to 30% and length increases of up to 45%. Histological analysis of tissue engineered PA showed tissue formation comparable to native. Biochemical analysis revealed the cell number and proteoglycan content comparable to native tissue and a significant increase in collagen content over time. The biomechanical analysis showed stronger but less elastic tissue properties compared to native tissue. Matrix metalloproteinases (MMP) as markers for tissue remodelling showed increased active MMP-2 and MMP-9 activity as compared to native tissue. • Conclusion There is on-going remodelling of the tissue engineered PA with increased haemodynamic demands of the growing model.

Peripheral arterial disease (PAD) is a common disease. There is substantial evidence that hyperhomocystelnaemia is associated with an increased risk of developing coronary and cerebral artery disease but little is known about hyperhomocysteinaemia, folate supplementation and PAD. This thesis presents the results of original PAD studies on the association of hyperhomocysteinaemia and homocysteine (Hey) genetic mutations; the role of folate therapy; and risk biomarkers, photoplethysmography (PPG) and pulse wave velocity (PVW) as novel techniques In assessing PAD severity. : A meta-analysis of 14 previous studies showed that raised concentrations of plasma tHcy were significantly associated with an increased risk of PAD.

Traditional risk factors for peripheral arterial disease (PAD) include smoking, hypertension, advanced age, diabetes and heart disease. These do not fully explain the differential nature of disease progression. Inflammatory and immunological factors have been increasingly implicated as active mediators of atherosclerotic disorders, including PAD. In particular, an imbalance between Thl and Th2 responses is thought to promote the progression of the atherosclerotic process. The extent of this imbalance in PAD is poorly understood. The aim of this study was therefore to examine the involvement of cytokines, anti- endothelial antibodies (AEA) such as anti-cardiolipin(a-CL) and anti-Bz-Glycoproteinl antibodiestanti-Bz-Gl'I) and antibodies to heat shock protein60 (aI?-ti-HSP60) as mediators of Thl and Th2 responses in the pathophysiology of this vascular disorder. Materials and Methods Patients included age-matched controls, stable claudicants (SC), critical limb ischaemics (Cl). Plasma baseline cytokine profiles, AEA and anti-HSP60 were analysed. Whole blood was stimulated with lipopolysaccharide (LPS) and analysed for interlukins by fluid-phase multiplex immunoassay. AEA and anti-HSP60 levels were determined by enzyme-linked immunosorbent assay. Data were analysed by Kruskall-Wallis tests and Mann-Whitney-U tests post hoc. 3 Results: Significantly higher levels of IL-6 were found in Cl compared to SC, which in turn were higher than in the Control group. IL-lO and IL-13 levels were higher in PAD subgroups (SC and Cl) versus control although there was no significant difference between PAD subgroups. AEA and anti-HSP60 levels tended to be higher in association with increasing PAD severity. However, while Cl Anti-B2-GPI levels were higher than in Control there was no significant difference in anti-CL levels. Anti-HSP60 was different in each of the three groups Clc-SCc-Control. Following an in vitro LPS challenge, unstandardized IL-8 and IL-13 production was higher in PAD patients compared to controls after 6h of incubation. However when these levels were standardized against the white cell count this effect was not seen. Conclusions: In conclusion, this study does not support either Thl or Th2 cytokines as being predominant in PAD (i.e., representing a Thl:Th2 imbalance), although inflammatory burden is more pronounced in severe manifestations of the disease. A minor degree of inflammatory hyper-responsiveness associated with cultured whole blood from SC and Cl patients appeared to relate to leukocytosis rather than being attributable to an inherent inflammatory dysfunction per se. The profile of all the mediators studied were however, seen to be influenced by disease severity.

The ci+ ion is a crucial signalling molecule that plays an essential role in cardiovascular physiology and pathology. Several proteins are known to control Ca2+ but understanding of the mechanisms involved remains relatively limited. The mammalian transient receptor potential (TRP) proteins can form non-selective cation channels and are implicated in cardiovascular abnormalities such as neointimal hyperplasia. TRPM3, TRPM2 and TRPC5 are examples of TRP channels that are widely expressed and involved in vascular cell functions. Sigma 1 receptor (Sig-IR) is a Ca2+ -regulatory ER protein that can translocate to the plasma membrane and modulate ion channels. Cholesterol is an essential component of cell membranes that has been suggested to modulate TRP channels such as TRPC 1. Translocon, an ER protein conducting channel, has been suggested to act as a Ca2+- leak channel in non-vascular cell types. The aim of this study was to investigate these mechanisms and factors in relation to human vascular cells. Multiple experimental approaches were used including intracellular Ca2+ measurements, RNA interference, quantitative RT-PCR, immunohistochemistry, and protein synthesis measurements. Cell culture, channels over-expressed in cell-line and I clinical samples from patients with coronary artery disease were the source of native cells. Structurally unrelated Sig-I R ligands, SKF 10047, 4- IBP, BD 1063 and BD 1 047 were used to explore the relationship ofTRP channels to Sig-IR. Importantly, all of the ligands inhibited TRPM3 activity but had no effects on TRPM2. However, Sig- lR siRNA studies failed to show a link of TRPM3 to Sig-IR .except for a component of the BDI047 effect. With TRPC5, except for potentiation by BDI063, Sig-l R ligands all produced strong inhibitory effects. Furthermore, so did the putative endogenous Sig-IR ligands; PregS, progesterone and dimethyltryptamine. In addition, Sig-l R ligands inhibited endogenous Ca2+ -entry signals in endothelial cells (ECs) evoked by histamine, vascular endothelial growth factor (VEGF) and H202 where endogenous TRP channels are suggested to be involved. However, again, Sig-lR siRNA revealed no role for Sig-lR. Moreover, immunohistochemistry results suggested that Sig-IR did not eo-localise with ] v TRPM3 or TRPC5. Therefore, the data suggest primarily direct effects of Sig-lR ligands on TRP channels and related endogenous Ca2+ signal of ECs but little or no role of Sig-I R itself. Metaphit, a non-selective sigma receptor antagonist, inhibited TRPM3, TRPC5 and TRPM2 activities and endogenous Ca2+-signals induced by histamine and H202 in ECs and by an oxidized phospholipid in VSMCs. Importantly, metaphit (1 IlM) inhibited the VEGF response in ECs. The data suggest that metaphit is a direct potent blocker ofTRP channels that may be useful as an anti-angiogenic agent. Cholesterol inhibited TRPC5 and potentiated TRPM2. It was shown to dissipate TRPC5 from the cell surface. In ECs, cholesterol regulated the Ca2+ -signal induced by histamine and VEGF. Interestingly, TRPCl siRNA indicated that cholesterol determines the molecular basis of the ECs Ca2+ -signal (i.e. TRPC 1 channel function required cholesterol). In the absence of cholesterol, histamine-induced Ca2+ -entry was mediated by other channels types and probably the CRAC channel based on the demonstrated sensitivity to synta-66 compound. To investigate the role of the tr~slocon as a passive ER Ca2+-leak mechanism in VSMCs, protein synthesis inhibitors, puromycin, anisomycin and emetine were used. The ligands inhibited radioactive methionine incorporation. The translocon opener, puromycin, evoked a transient elevation in cytoplasmic Ca2+ that was abolished by thapsigargin and inhibited by the translocon blockers, anisomycin and emetine, indicating the capacity of the translocon to act as an ER Ca2+ -leak channel. However, the translocon ligands had no effect on thapsigargin, ionomycin, ATP or " endothelin-l-induced Ca2+ -release, indicating that the translocon is normally closed and lacks relevance to calcium leak in VSMCs. In summary, this study showed novel modulation of TRP channels and endogenous Ca2+ -signals by Sig-I R ligands, importance of cholesterol in TRP channel function and capability of the translocon as a Ca2+ -leak pathway in proliferating VSMCs but excluded its physiological role.