The objective was to assess the effect of a high-monounsaturated fat (MUFA) dietary portfolio of cholesterol-lowering foods on oxidative stress and cardiovascular risk. Twenty-four hyperlipidemic subjects followed a very low-saturated-fat therapeutic control diet for 4 weeks after which they were randomized to receive the dietary portfolio, consisting of soy protein (20g/1000kcal), viscous fibre (10.3g/1000kcal), plant sterols (2-3g) and almonds (21.5g/1000kcal), in combination with high- or low-MUFA (25.9% and 12.9% MUFA, respectively) for the next 4 weeks, where MUFA replaced 13.0% of dietary carbohydrate. On high-MUFA, there were significantly greater increases in HDL-C and apoA1 and significantly greater reductions in total:high-density lipoprotein cholesterol (total:HDL-C) ratio and high-sensitivity C-reactive protein (hs-CRP) compared to the low-MUFA dietary portfolio. In all diets there were significant increases in protein thiols and reductions in conjugated dienes and thiobarbituric acid reactive substances (TBARS) measured in the LDL-fraction, however no difference between the high- and low-MUFA diets.

Thick composites (~ 3 mm in thickness) of polypyrrole with electrically insulating porous (polystyrene) and nonporous (polymethyl methacrylate) substrates were prepared using a two-step batch method. In the two-step method, impregnation of volatile (iodine) or nonvolatile (ferric chloride) oxidant in the substrate is followed by in-situ polymerization of pyrrole. Conductivities as high as 10-1 S/cm were obtained in this work in the case of composites of polypyrrole and porous, crosslinked polystyre. Use of the nonvolatile oxidant (ferric chloride) resulted in higher conducting polymer yield, as well as composites having a higher conductivity, thermal stability, and mechanical strength. However, the volatile oxidant (iodine) could be transported to the substrate using supercritical carbon dioxide as the solvent. As a result, partitioning of the oxidant between the solvent phase and the polymer substrate, and hence the distribution of the oxidant in the substrate, could be controlled by manipulation of the pressure. The two-step batch method in which supercritical carbon dioxide is used to facilitate transport and as a solvent for the oxidant was found to be an effective method for the production of thick composites with uniform conductivity, thermal stability, and mechanical strength. Such composites are desired in important practical applications such as rechargeable battery electrodes and electromagnetic interference shielding materials.

Nitrogen ligands have been little studied with gold(I) and almost no chemistry has been described using anionic bridging nitrogen ligands. This dissertation concerns the impact of the bridging ligands amidinate, ArNHC(H)NAr, on the chemistry of gold(I) and, in particular, the effect of substituents on the molecular arrangement. The electronic vs. steric effect of the substituents on the molecular arrangement of gold(I) amidinates complexes is studied in detail. Tetra-, tri-, and dinuclear gold(I) amidinate complexes are synthesized and characterized using X-ray diffraction. Spectroscopic and electrochemical studies of the amidinate complexes are described. Catalytic studies suggest that gold amidinates and related gold nitrogen complexes are the best catalyst precursors for CO oxidation on TiO2 surface reported to date (87% conversion). The dinuclear gold(I) amidinate complex with a Auâ ¦Au distance of 2.711(3) Ã is rare. To our knowledge, there is only one other example of a symmetrical dinuclear gold(I) nitrogen complex. Oxidative-addition reactions to the dinuclear gold(I) complex, [Au2(2,6-Me2-form)2] are studied in detail and result in the formation of gold(II) complexes. The gold(II) amidinate complexes are the first formed with nitrogen ligands. The complexes are stable at room temperature. Mixed ligand tetranuclear gold(I) clusters and tetranuclear mixed Au-Ag metal clusters of pyrazolate and amidinate ligands are synthesized and characterized using Xray diffraction.

Gene expression was examined in vascular smooth muscle cells to study the complex interaction between oxidative injury and the pathogenesis of vascular disease. Extensive vascular remodeling coupled to increased production of 8-epi-PGF2α nuclear localization of NFκB, and alterations in glutathione homeostasis were identified as major responses of the vascular wall to oxidative stress. Transcriptional profiling studies, supported by immunohistochemistry and in situ hybridization measurements, identified genes involved in adhesion and extracellular matrix deposition (α1 integrin, collagen), cytoskeletal rearrangements (α-smooth muscle actin, α-tropomyosin), and signal transduction (NFκB, osteopontin, and LINE) as targets of oxidant injury. In the case of osteopontin (OPN), elevation of OPN levels in vSMCs was shown to be mediated by redox-regulated transcriptional mechanisms. A 200bp region located in the 5' UTR of the osteopontin promoter was found to be responsive to oxidative stress. This regulatory region contained two distinct cis acting elements involved in promoter inducibility. These elements were tentatively identified as NFKB and TIEG-1 binding sites and shown to be highly responsive to hydrogen peroxide and chemical antioxidants. Collectively these studies answer central questions regarding the mechanisms underlying the vascular response to oxidative stress and the involvement of OPN in diseases of the vascular wall.

ADM is a 52-amino acid peptide which carries out multiple biological functions in cardiovascular system such as vasodilation and hypotension, and is a prognostic marker for cardiovascular diseases. Recent studies show that its plasma level is elevated in diabetes, however the reason and significance for such an increase has not been understood. Recent research has proposed that inflammation and oxidative stress both contribute to the pathogenesis of diabetes. If ADM is a marker in diabetes, it is possible that ADM is regulated by these two mechanisms, and so this project aims to investigate how these mechanisms could affect ADM expression. Recent studies have demonstrated that advanced glycation endproducts (AGEs) could lead to development of various diabetic complications. AGEs are formed as intermediate product in the non-enzymatic glycation of reducing sugars. Formation of these products is stimulated by hyperglycemia and oxidative stress, which could also induce ADM expression. Hence one of the studies investigated the direct effect of AGEs on ADM expression in an in vitro model. A rat macrophage cell line NR8383 was used to investigate the dose-response and time-point responses of macrophage cells in expressing ADM stimulated by AGEs. 6 hours of AGEs treatment resulted in no significant effect on ADM gene expression. The gene expression increased in all time points in which the change was at maximum after 1 hour of AGE treatment compared with other time points (P<0.05). However the time-dependent effect on ADM gene expression was insignificant compared with controls. How oxidative stress could lead to increased ADM expression deserves further investigation. ADM plays a role in inflammation that it could influence IL-6 and adiponectin expressions. This project also investigated whether IL-6 and adiponectin could affect ADM levels on the opposite. The associations between IL6 and adiponectin single nucleotide polymorphisms (SNPs) with plasma ADM levels were studied using a cohort of 476 subjects from the Cardiovascular Risk Factor Prevalence Study (CRISPS). Specific tagging SNPs were genotyped for the 476 subjects. Significant associations were identified for the IL6 SNP rs17147230 and adiponectin SNP rs182052 with plasma ADM levels in additive model (β=-0.096, P=0.034, and β=0.104, P=0.023 respectively adjusting for age and sex). The associations remained significant after adjusting for various covariates (P<0.05). Genotypic model shows that the minor alleles of rs17147230 and rs182052 resulted in 12.8% decrease and 17.7% increase in plasma ADM levels. These findings show that ADM level could be regulated by IL-6 which is an inflammatory cytokine, and adiponectin which is a protective peptide in inflammation. Reducing inflammation could lower ADM level and adiponectin might be a therapeutic candidate. / published_or_final_version / Medicine / Master / Master of Philosophy

Vitamin E (a-tocopherol) is the major lipid soluble antioxidant in vivo and is important for maintaining the integrity of cell membranes. Oxidative stress, defined as an imbalance between oxidants and antioxidants, has been implicated in the aetiology of numerous diseases. There is, therefore, interest in establishing methods to measure oxidative stress. It has been suggested that metabolites of vitamin E such as atocopheronolactone (a-TL), with an oxidised chroman ring, may be an indicator of in vivo oxidative stress and that the carboxyethyl-hydroxychromans (CEHCs), with a shortened phytyl side chain, may provide a measure of adequate or excess vitamin E status. However, doubts have been raised about the authenticity of a-TL since a-CEHC has been shown to be artefactually oxidised to a-TL in many of the procedures described. In the course of the current study a relatively simple method using gas chromatographymass spectrometry (GC-MS) was developed which allowed the reproducible measurement of a wide range of deconjugated vitamin E metabolites in urine. This method was used to study the urinary metabolites produced by normal subjects before and after supplementation with vitamin E. The CEHCs were confirmed as the major urinary metabolites of vitamin E, a-TL was detected and a novel group of metabolites, the carboxymethylbutyl-hydroxychromans (CMBHCs), was also tentatively identified. A range of conjugated (sulphated and glucuronidated) and free metabolites of vitamin E were synthesised chemically and used to a) confirm the identity of (x-CMBHC, b) provide standards for GC-MS and tandem mass spectrometry, c) elucidate the mechanism of artefactual oxidation and to develop new methods for the precise measurement of endogenously produced a-TL and d) investigate the type of conjugation of the various metabolites of vitamin E in human urine.

No description available.

No description available.

The soluble and readily extractable part of the plant extracellular matrix has been termed, the apoplast and contains a wide range of components such as, complex carbohydrates, structural proteins, enzymes and radicals that are known to be responsive to stress and developmental pressures. This thesis describes the development of a technique for the selective enrichment of apoplastic components for a range of subsequent analyses. Using this technique a number of apoplastic proteins were N-terminally sequenced and revealed 2 cell wall related enzymes, an antifungal protein and 3 auxin-binding/germin-like proteins. This technique also provided a novel approach to the further study of auxin-binding proteins via the use of affinity chromatography at their putative site of action, the apoplast. Three potential auxin-binding protiens were identified. Many attempts were made to subject the material extracted from the apoplast to the highly resolving technique of 2-dimensional electrophoresis, and during the process two unusual 2D systems were developed. These systems could be run in a small format that permitted very rapid analysis and/or using an in-gel loading strategy to subject up to 500µg of protein to 2D separation therefore permitting N-terminal sequencing from single 2D gels. Unfortunately 2D separation of apoplastic proteins was never fully achieved within the time frame of this study due to the vast degree of heterogenity present in the sample material. It did however demonstrate the very complex nature of apoplastic components. A series of experiments revealed that the tobacco leaf apoplast contained compartment specific antioxidant enzymes, some of which share physical characteristics with similar enzymes from other species. The activity of these enzymes altered in response to stress and according to the developmental age of the tissue. The reduced activity of these enzymes directly correlated to the degree of oxidative modification of apoplastic proteins illustrating that these enzymes are important in the detoxification of apoplastic radicals. Follow on experiments following the apoplastic generation of the superoxide anion and nitric oxide from impact stressed potato tuber tissue showed that radicals play important roles in the responses of plant tissue to stress, and show the first involvement of nitric oxide in plants in response to abiotic stress.

The objective was to assess the effect of a high-monounsaturated fat (MUFA) dietary portfolio of cholesterol-lowering foods on oxidative stress and cardiovascular risk. Twenty-four hyperlipidemic subjects followed a very low-saturated-fat therapeutic control diet for 4 weeks after which they were randomized to receive the dietary portfolio, consisting of soy protein (20g/1000kcal), viscous fibre (10.3g/1000kcal), plant sterols (2-3g) and almonds (21.5g/1000kcal), in combination with high- or low-MUFA (25.9% and 12.9% MUFA, respectively) for the next 4 weeks, where MUFA replaced 13.0% of dietary carbohydrate. On high-MUFA, there were significantly greater increases in HDL-C and apoA1 and significantly greater reductions in total:high-density lipoprotein cholesterol (total:HDL-C) ratio and high-sensitivity C-reactive protein (hs-CRP) compared to the low-MUFA dietary portfolio. In all diets there were significant increases in protein thiols and reductions in conjugated dienes and thiobarbituric acid reactive substances (TBARS) measured in the LDL-fraction, however no difference between the high- and low-MUFA diets.