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Showing 1301–1320 of 2058 publications.
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Fryirs, Michelle A.; Barter, Philip J.; Rye, Kerry AnneCholesterol is important for ?-cell function and survival. It can cause ?-cell loss if allowed to accumulate in the cells in an unregulated manner. The maintenance of ?-cell cholesterol homeostasis, therefore, is important for preventing ?-cell dysfunction, the onset of insulin resistance and the development of type 2 diabetes. 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins.
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Patel, Sanjay; Drew, Brian G.; Nakhla, Shirley; Duffy, Stephen James; Murphy, Andrew James; Barter, Philip J.; Rye, Kerry Anne; Chin-Dusting, Jaye P.F.; Hoang, Anh; Sviridov, Dmitri D.; Celermajer, David S.; Kingwell, BronwynObjectives: Our aim was to investigate the effects of reconstituted high-density lipoprotein (rHDL) infusions on plasma high-density lipoprotein (HDL) anti-inflammatory properties and ex vivo cholesterol efflux in patients with type 2 diabetes. Background: The anti-inflammatory effects of HDL contribute to protection from cardiovascular events. Individuals with type 2 diabetes are at elevated risk for cardiovascular disease, and typically have low HDL with reduced anti-inflammatory properties. Methods: Thirteen fasting male patients (mean age 52 years) with type 2 diabetes mellitus received both rHDL (80 mg/kg of apolipoprotein A-I) and a saline placebo on separate occasions in a randomized cross-over design study. Changes in the ability of isolated HDL to influence the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in human coronary artery endothelial cells was the main outcome measure. Other outcome measures included expression of the key integrin, CD11b on patient monocytes, adhesiveness of patient neutrophils to fibrinogen, and the ability of plasma to promote cholesterol efflux to THP-1 macrophages. Results: Four and 72 h post-rHDL infusion, the anti-inflammatory properties of isolated HDL increased in parallel to their concentration in plasma (by up to 25%, p < 0.01). Participants' peripheral blood monocyte CD11b expression and neutrophil adhesion to a fibrinogen matrix was also reduced 72 h post-rHDL, compared with that seen in placebo (p = 0.02). rHDL increased the capacity of plasma to receive cholesterol from THP-1 macrophages by 1 h up to 72 h post-infusion (by 40% to 60%, p < 0.05). Conclusions: rHDL infusions have significant, potentially atheroprotective effects in individuals with diabetes, including suppression of inflammation and enhancement of cholesterol efflux. 2009 American College of Cardiology Foundation.
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Ling, Hua; Waterworth, Dawn M.; Stirnadel-Farrant, Heide A.; Pollin, Toni I.; Barter, Philip J.; Kesaniemi, YrjAntero; Mahley, Robert W.; McPherson, Ruth M.; Waeber, Gard; Bersot, Thomas P.; Cohen, Jonathan C.; Grundy, Scott M.; Mooser, Vincent E.; Mitchell, Braxton D.Adiponectin has a variety of metabolic effects on obesity, insulin sensitivity, and atherosclerosis. To identify genes influencing variation in plasma adiponectin levels, we performed genome-wide linkage and association scans of adiponectin in two cohorts of subjects recruited in the Genetic Epidemiology of Metabolic Syndrome Study. The genome-wide linkage scan was conducted in families of Turkish and southern European (TSE, n = 789) and Northern and Western European (NWE, N = 2,280) origin. A whole genome association (WGA) analysis (500K Affymetrix platform) was carried out in a set of unrelated NWE subjects consisting of approximately 1,000 subjects with dyslipidemia and 1,000 overweight subjects with normal lipids. Peak evidence for linkage occurred at chromosome 8p23 in NWE subjects (lod = 3.10) and at chromosome 3q28 near ADIPOQ, the adiponectin structural gene, in TSE subjects (lod = 1.70). In the WGA analysis, the single-nucleotide polymorphisms (SNPs) most strongly associated with adiponectin were rs3774261 and rs6773957 (P < 10-7). These two SNPs were in high linkage disequilibrium (r 2 = 0.98) and located within ADIPOQ. Interestingly, our fourth strongest region of association (P < 2 10-5) was to an SNP within CDH13, whose protein product is a newly identified receptor for high-molecular-weight species of adiponectin. Through WGA analysis, we confirmed previous studies showing SNPs within ADIPOQ to be strongly associated with variation in adiponectin levels and further observed these to have the strongest effects on adiponectin levels throughout the genome. We additionally identified a second gene (CDH13) possibly influencing variation in adiponectin levels. The impact of these SNPs on health and disease has yet to be determined.
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Rye, Kerry Anne; Bursill, C. A.; Lambert, Gilles; Tabet, Fatiha; Barter, Philip J.Population studies have shown that plasma HDL levels correlate inversely with cardiovascular disease risk. In recent years there has been intense interest in developing strategies for exploiting these cardioprotective properties by increasing HDL levels. While this approach has considerable merit, it is important to recognize that HDL are structurally and functionally diverse and consist of numerous, highly dynamic subpopulations of particles that do not all inhibit atherosclerosis to the same extent. For this reason it is essential to assess HDL subpopulation distribution and functionality when considering therapeutic interventions that raise HDL levels. This review documents what is known about the relationship between the metabolism and function of HDL subpopulations and how this affects their cardioprotective properties. Copyright 2009 by the American Society for Biochemistry and Molecular Biology, Inc.
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Hawkins, Clare L.; Morgan, Philip E.; Davies, Michael J.Proteins are major targets for oxidative damage due to their abundance and rapid rates of reaction with a wide range of radicals and excited state species, such as singlet oxygen. Exposure of proteins to these oxidants results in loss of the parent amino acid residue, formation of unstable intermediates, and the generation of stable products. Each of these events can be used, to a greater or lesser extent, to quantify damage to proteins. In this review the advantages and disadvantages of a number of these approaches are discussed, with an emphasis on methods that yield absolute quantitative data on the extent of protein modification. Detailed methods sheets are provided for many of these techniques. 2009 Elsevier Inc. All rights reserved.
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Sieveking, Daniel P.; Ng, Martin K.C.The discovery, over a decade ago, of endothelial progenitor cells that are able to participate in neovascularization of adult tissue has been greeted enthusiastically because of the potential for new cell-based therapies for therapeutic angiogenesis. Since that time, an ever-growing list of candidate cells has been proposed for cardiovascular regeneration. However, to date, pre-clinical and clinical studies evaluating the therapeutic potential of various cell therapies have reported conflicting results, generating controversy. Key issues within the field of cell therapy research include a lack of uniform cellular definitions, as well as inadequate functional characterization of the role of putative stem/progenitor cells in angiogenesis. Given the mixed results of initial clinical studies, there is now a scientific imperative to understand better the vascular biology of candidate cells in order to better translate cell therapy to the bedside. This review will provide a translationally relevant overview of the biology of candidate stem/progenitor cells for therapeutic angiogenesis. The Author(s), 2009.
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Pattison, David I.; Hawkins, Clare L.; Davies, Michael J.Myeloperoxidase (MPO) is a heme enzyme, released by activated leukocytes at sites of inflammation, which catalyzes the formation of the potent oxidant, hypochlorous acid (HOCl), from H<inf>2</inf>O<inf>2</inf>. HOCl is a key component of the inflammatory response and is bactericidal but has been linked with several human pathologies as a result of damage to host tissue. Elevated plasma MPO levels are a strong independent risk factor, and predictor of outcomes, for cardiovascular disease. Rate constants for reaction of HOCl with individual biological targets and the products of these reactions have been determined, but the targets of HOCl in complex biological fluids such as plasma are incompletely defined. In this study, rate constants (M-1 s -1) for the reactions of ascorbate with HOCl (ca. 6 10 6) and imidazole chloramine (7.7 104) have been determined to supplement known kinetic parameters. HOCl-mediated oxidation of the major plasma protein, albumin, was investigated both experimentally and computationally; these approaches provide consistent data. The computational studies were extended to examine the fate of HOCl in plasma. The model predicts that plasma proteins consume the majority of HOCl with limited damage to other materials. Ascorbate or ?-tocopherol, even at the levels achieved in human supplementation studies, do not attenuate these reactions. In contrast, elevated levels of thiocyanate ions (SCN-), as detected in heavy smokers, can modulate HOCl-mediated reactions as a result of the formation of the highly specific oxidant hypothiocyanous acid (HOSCN). These observations support the hypothesis that MPO-generated HOSCN is a key agent in smoking-enhanced atherosclerosis. 2009 American Chemical Society.
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McGrath, Kristine C.Y.; Li, Xiaohong; Puranik, Rajesh; Liong, Eleanore C.; Tan, Joanne Tsui Ming; Dy, V. M.; Di Bartolo, Belinda Ann; Barter, Philip J.; Rye, Kerry Anne; Heather, Alison KayOBJECTIVE-: The purpose of this study was to investigate the ability of high-density lipoproteins (HDLs) to upregulate genes with the potential to protect against inflammation in endothelial cells. METHODS AND RESULTS-: Human coronary artery endothelial cells (HCAECs) were exposed to reconstituted HDLs (rHDLs) for 16 hours before being activated with tumor necrosis factor-? (TNF-?) for 5 hours. rHDLs decreased vascular cell adhesion molecule-1 (VCAM-1) promoter activity by 75% (P<0.05), via the nuclear factor-kappa B (NF-?B) binding site. rHDLs suppressed the canonical NF-?B pathway and decreased many NF-?B target genes. Suppression of NF-?B and VCAM-1 expression by rHDLs or native HDLs was dependent on an increase in 3?-hydroxysteroid-?24 reductase (DHCR24) levels (P<0.05). The effect of HDLs on DHCR24 is dependent on SR-BI but not ABCAI or ABCGI. Silencing DHCR24 expression increased NF-?B (1.2-fold, P<0.05), VCAM-1 (30-fold, P<0.05), and NF-?B p50 (4-fold, P<0.05) and p65 subunits (150-fold, P<0.05). TNF-? activation of siDHCR24-treated cells increased expression of VCAM-1 (550-fold, P<0.001) and NF-?B (9-fold, P<0.001) that could no longer be suppressed by rHDLs. CONCLUSIONS-: Results suggest that antiinflammatory effects of rHDLs are mediated partly through an upregulation of DHCR24. These findings raise the possibility of considering DHCR24 as a target for therapeutic modulation. 2009 American Heart Association, Inc.
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Taskinen, Marja Riitta; Sullivan, David R.; Ehnholm, Christian P.; Whiting, Malcolm J.; Zannino, Diana; Simes, Robert John; Keech, Anthony C.; Barter, Philip J.OBJECTIVE-: The purpose of this study was to determine fenofibrate-induced changes in plasma high-density lipoprotein cholesterol (HDL-C), apoliprotein (apo) A-I, and apolipoprotein (apo) A-II and how they relate to changes in plasma homocysteine and creatinine. METHODS AND RESULTS-: FIELD was a double-blind placebo-controlled trial done in Australia, New Zealand, and Finland. All FIELD subjects were included except those who started statin therapy or permanently discontinued fenofibrate. Patients were randomized to receive daily micronised fenofibrate (200 mg) or matching placebo and were followed up for a median of 5 years. Plasma HDL-C, apoA-I, apoA-II, homocysteine, and creatinine were measured. There was an inverse relationship between baseline homocysteine levels and HDL-C in the placebo (P=0.07 for linear trend) and fenofibrate groups (P<0.0001) and apoA-I (P<0.001, both groups). The increases in homocysteine and creatinine in the fenofibrate group correlated positively (P<0.0001). The greater the increase in homocysteine induced by fenofibrate, the smaller the increases in HDL-c and apoA-I (P<0.0001 for linear trends). There was a highly significant and positive relationship between fenofibrate-induced changes in homocysteine and apoA-II levels. CONCLUSIONS-: PPAR? agonists that have a more robust effect on HDL-C and apoA-I would be desirable. 2009 American Heart Association, Inc.
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Ayer, Julian Ganesh J.; Harmer, Jason A.; Nakhla, Shirley; Xuan, Wei; Ng, Martin K.C.; Raitakari, Olli T.; Marks, Guy B.; Celermajer, David S.OBJECTIVE-: Atherosclerosis is found at autopsy in the arteries of adolescents and young adults. Arterial wall thickening may be assessed in vivo by ultrasound measurement of the carotid intima media thickness (CIMT), a marker of subclinical atherosclerosis. As the determinants of arterial wall thickness in childhood are unknown, we assessed the influence of cardiovascular risk factors on CIMT in 8-year-old children. METHODS AND RESULTS-: A community-based sample of 405 children (age 8.00.1 years, 49% girls) had anthropometry, family history, blood pressure (BP), and CIMT measured. A blood sample was collected for HDL and non-HDL cholesterol, apolipoproteins A1 and B, high-sensitivity C-reactive protein, bilirubin, and asymmetric dimethylarginine (ADMA, an endogenous nitric oxide inhibitor). CIMT was significantly associated with systolic BP (r=0.17, P<0.001), diastolic BP (r=0.10, P=0.04), HDL (r=-0.13, P=0.02), and ADMA (r=0.18, P=0.001). CIMT was significantly higher in children with premature parental CHD (0.630.07 versus 0.590.06 mm, P=0.03). On multivariate analysis, HDL (? coefficient=-0.02, P=0.04), ADMA (? coefficient=0.05, P<0.001), and systolic BP (? coefficient=0.001, P=0.003) were significantly and independently associated with CIMT. CONCLUSIONS-: Lower HDL-cholesterol, higher levels of ADMA, and systolic BP are significantly associated with greater arterial wall thickness in early childhood. 2009 American Heart Association, Inc.
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Kennett, Eleanor C.; Davies, Michael J.Glycosaminoglycans (long-chain polysaccharides) are major components of the extracellular matrix, glycocalyx, and synovial fluid. These materials provide strength and elasticity to tissues and play a key role in regulating cell behavior. Modifications to these materials have been linked to multiple human pathologies. Although modification may occur via both enzymatic and nonenzymatic mechanisms, there is considerable evidence for oxidant-mediated matrix damage. Peroxynitrite (ONOO-/ONOOH) is a potential mediator of such damage, as elevated levels of this oxidant are likely to be present at sites of inflammation. In this study we demonstrate that hyaluronan and chondroitin sulfate are extensively depolymerized by HO{dot operator} and CO<inf>3</inf>{dot operator}-, but not NO<inf>2</inf>{dot operator}, which may be formed from peroxynitrite. Polymer fragmentation is shown to be dependent on the radical flux, to be O<inf>2</inf>-independent, and to occur in a site-selective manner as indicated by the detection of disaccharide fragments. EPR spin trapping experiments with polymers, oligomers, and component monosaccharides, including 13C-labeled materials, have provided evidence for the formation of specific carbon-centered sugar-derived radicals. The time course of formation of these radicals is consistent with these species being involved in polymer fragmentation. 2009 Elsevier Inc. All rights reserved.
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Patel, Sanjay; Puranik, Rajesh; Nakhla, Shirley; Lundman, Pia; Stocker, Roland; Wang, Xiaosuo; Lambert, Gilles; Rye, Kerry Anne; Barter, Philip J.; Nicholls, Stephen J.; Celermajer, David S.Introduction: Post-prandial hypertriglyceridaemia is a risk factor for cardiovascular disease, although the underlying mechanisms remain unclear. High density lipoproteins (HDL) have been shown to be atheroprotective, in part through attenuation of vascular inflammation. In this study, the influence of acute hypertriglyceridaemia on the composition and anti-inflammatory properties of HDL was investigated. Methods: Eight fasting healthy male subjects (34 2 years) received 20% Intralipid (15 mg/kg/h) or saline, on separate occasions in random order. At baseline and 60 min post-infusion, the total HDL fraction was isolated and its chemical composition determined. HDL were added to TNF-? stimulated human coronary artery endothelial cells and VCAM-1 and ICAM-1 expression was determined by flow cytometry. Results: Serum triglyceride (97.4 8.5 mg/dL baseline, 283.2 35.4 mg/dL post-infusion, p < 0.001) and HDL triglyceride content (3.8 0.5% HDL mass baseline, 5.3 0.9% HDL mass post-infusion, p < 0.05) increased significantly after Intralipid infusion. HDL post-Intralipid were significantly less anti-inflammatory compared with control (e.g. at 8 ?M apoA-I, %VCAM-1 expression 54 5 post-saline, 73 4 post-Intralipid, p = 0.01; %ICAM-1 expression 94 1 post-saline, 99.4 0.6 post-Intralipid, p < 0.01). There was also a significant correlation between HDL triglyceride content and VCAM-1 expression (R = 0.70, p = 0.005); as well as between plasma triglyceride levels and both VCAM-1 (R = 0.71, p < 0.005) and ICAM-1 expression (R = 0.80, p < 0.005). Conclusion: Acute hypertriglyceridaemia, simulating the post-prandial state, results in triglyceride-rich HDL with impaired anti-inflammatory capacity. 2008 Elsevier Ireland Ltd.
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Gracanin, Michelle; Hawkins, Clare L.; Pattison, David I.; Davies, Michael J.Proteins are major biological targets for oxidative damage within cells owing to their high abundance and rapid rates of reaction with radicals and excited-state species, including singlet oxygen. Reaction of Tyr, Trp, and His residues, both free and on proteins, with singlet oxygen generates peroxides in high yield. Peroxides have also been detected on proteins within intact cells on exposure to visible light in the presence of a photosensitizer. The structures of some of these materials have been elucidated for free amino acids, but less is known about peptide- and protein-bound species. In this study we have characterized Trp-derived peroxides, radicals, and breakdown products generated on free Trp and Trp residues in peptides and proteins, using LC/MS/MS. With free Trp, seven major photoproducts were characterized, including two isomeric hydroperoxides, two alcohols, two diols, and N-formylkynurenine, consistent with singlet oxygen-mediated reactions. The hydroperoxides decompose rapidly at elevated temperatures and in the presence of reductants to the corresponding alcohols. Some of these materials were detected on proteins after complete enzymatic (Pronase) hydrolysis and LC/MS/MS quantification, providing direct evidence for peroxide formation on proteins. This approach may allow the quantification of protein modification in intact cells arising from singlet oxygen formation. 2009 Elsevier Inc. All rights reserved.
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Wat, Elaine C.L.; Tandy, Sally; Kapera, Ewa; Kamili, Alvin; Chung, Rosanna W.S.; Brown, Andrew; Rowney, Michelle K.; Cohn, Jeffrey S.Recent studies have suggested that milk and certain dairy food components have the potential to protect against cardiovascular disease. In order to determine whether the addition of milk-derived phospholipids to the diet results in an improvement in metabolic and cardiovascular risk factors, we studied four groups (n = 10) of C57BL/6 mice that were fed: (1) a normal non-purified diet (N); (2) the normal non-purified diet supplemented with phospholipid-rich dairy milk extract (PLRDME, 2.5% by wt) (NPL); (3) a high-fat semi-purified diet (HF) containing 21% butterfat + 0.15% cholesterol by wt; or (4) HF supplemented with 2.5% by wt PLRDME (HFPL). Dietary PLRDME supplementation did not have a significant effect on metabolic parameters in mice fed the N diet. In contrast, in high-fat fed mice, PLRDME caused a significant decrease in: (a) liver wt (1.57 0.06 g vs. 1.20 0.04 g, P < 0.001), (b) total liver lipid (255 22 mg vs. 127 13 mg, P < 0.001, (c) liver triglyceride (TG) and total cholesterol (TC) 236 25 ?mol/g vs. 130 8 ?mol/g (P < 0.01), 40 7 ?mol/g vs. 21 2 ?mol/g (P < 0.05), respectively); and serum lipids (TG: 1.4 0.1 mmol/L vs. 1.1 0.1 mmol/L, P = 0.01; TC: 4.6 0.2 mmol/L vs. 3.6 0.2 mmol/L, P < 0.001; and PL: 3.3 0.1 mmol/L vs. 2.6 0.1 mmol/L, P < 0.01). These data indicate that dietary PLRDME has a beneficial effect on hepatomegaly, hepatic steatosis and elevated serum lipid levels in mice fed a high-fat diet, providing evidence that PLRDME might be of therapeutic value in human subjects as a hepatoprotective or cardioprotective nutraceutical. 2008 Elsevier Ireland Ltd. All rights reserved.
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Royle, Caroline M.; Lim, Shirlene M.; Xu, Bei; Tooher, Jane M.; Ogle, Robert F.; Hennessy, AnnemarieIntroduction: The placenta plays a pivotal role in the pathophysiology of preeclampsia. Insufficient trophoblast invasion within the placenta can cause focal regions of ischaemia/hypoxia that, in turn, may stimulate the production of inflammatory cytokines. These cytokines are thought to cause endothelial cell activation and dysfunction, resulting in the clinical signs of preeclampsia. In addition to insufficient trophoblast invasion, the presence of inadequate maternal vasculature remodelling by trophoblasts also leads to changes in angiogenesis that may result from variations in the inflammatory cytokine profile. Aims: This study examined changes in the protein levels of IL-10 (immunoregulatory), TNF-? (pro-inflammatory) and sFlt-1 (anti-angiogenic) in normal term placentas under different oxygen tensions. The second aim was to determine if the link between varying levels of the cytokine, IL-10, and the expression/release of TNF-? was oxygen dependent, and whether there was a concurrent change in sFlt-1. Methods: Normal term placentas (n = 6) were cultured at three different oxygen tensions (2%, 8% or 21%) in the presence or absence of exogenous IL-10. Protein (TNF-? and sFlt-1) secretion was measured using commercial ELISA kits, and qRT-PCR was used to examine gene expression. Results: Placental IL-10 release was significantly reduced at 2% oxygen when compared to 8% (p = 0.045) and 21% (p = 0.013). Expression of TNF-? and sFlt-1 was not significantly different. Exogenous IL-10 significantly reduced TNF-? protein levels only when explants were cultured in 2% oxygen (p = 0.05). Soluble Flt-1 protein secretion was unaffected by the addition of IL-10 at any of the oxygen tensions tested. Conclusion: TNF-? release can be inhibited in vitro by IL-10 under hypoxic conditions. However, IL-10 has no affect on sFlt-1 in term placentas, suggesting that these molecules act either via different pathways, or if linked, may be so at different stages of placental development. 2009 Elsevier Ltd. All rights reserved.
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Rees, Martin D.; Bottle, Steven E.; Fairfull-Smith, Kathryn E.; Malle, Ernst; Whitelock, John; Davies, Michael J.Tissue damage resulting from the extracellular production of HOCl (hypochlorous acid) by the MPO (myeloperoxidase)-hydrogen peroxide-chloride system of activated phagocytes is implicated as a key event in the progression of a number of human inflammatory diseases. Consequently, there is considerable interest in the development of therapeutically useful MPO inhibitors. Nitroxides are well established antioxidant compounds of low toxicity that can attenuate oxidative damage in animal models of inflammatory disease. They are believed to exert protective effects principally by acting as superoxide dismutase mimetics or radical scavengers. However, we show here that nitroxides can also potently inhibit MPO-mediated HOCl production, with the nitroxide 4-aminoTEMPO inhibiting HOCl production by MPO and by neutrophils with IC<inf>50</inf> values of approx. 1 and 6 ?M respectively. Structure-activity relationships were determined for a range of aliphatic and aromatic nitroxides, and inhibition of oxidative damage to two biologically-important protein targets (albumin and perlecan) are demonstrated. Inhibition was shown to involve one-electron oxidation of the nitroxides by the compound I form of MPO and accumulation of compound II. Haem destruction was also observed with some nitroxides. Inhibition of neutrophil HOCl production by nitroxides was antagonized by neutrophil-derived superoxide, with this attributed to superoxide-mediated reduction of compound II. This effect was marginal with 4-aminoTEMPO, probably due to the efficient superoxide dismutase-mimetic activity of this nitroxide. Overall, these data indicate that nitroxides have considerable promise as therapeutic agents for the inhibition of MPO-mediated damage in inflammatory diseases. The Authors Journal compilation. 2009 Biochemical Society.
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Peshavariya, Hitesh Mahendrabhai; Dusting, Gregory James; Di Bartolo, Belinda Ann; Rye, Kerry Anne; Barter, Philip J.; Jiang, FanReconstituted discoidal high-density lipoprotein (rHDL) has potent vascular protective actions. Native HDL suppresses cellular generation of reactive oxygen species, whereas this antioxidant effect of rHDL is less clear. This study examined the effects of rHDL on NADPH oxidase, a major source of cellular superoxide generation, in both leukocytes and human umbilical vein endothelial cells. Superoxide was measured with lucigenin-enhanced chemiluminescence. Expression of NADPH oxidase sub-units was determined by real-time PCR. Pre-treatment of HL-60 cells with rHDL (10 and 25 ?M) for 1 h significantly reduced phorbol 12-myristate 13-acetate-stimulated superoxide production. Treatment with rHDL for up to 24 h did not change the mRNA expression of NADPH oxidase sub-units. In HL-60 cells, depletion of cholesterol from the plasma membrane by methyl-?-cyclodextrin mimicked the effect of rHDL, whereas cholesterol repletion blunted the effects of rHDL. Treatment with rHDL induced disruption of the lipid raft structures and blunted PMA-induced redistribution of p47phox into lipid rafts. In contrast, treatment of endothelial cells with rHDL for up to 18 h had no effect on either basal or tumour necrosis factor-?-stimulated NADPH oxidase activity, but markedly suppressed the cytokine-induced expression of proinflammatory adhesion molecules. The results suggest that rHDL inhibits NADPH oxidase activation in leukocytes, probably by interrupting the assembly of NADPH oxidase sub-units at the lipid rafts. This effect may contribute to the vascular protective actions of rHDL against inflammation-mediated oxidative damage.
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Ayer, Julian Ganesh J.; Harmer, Jason A.; Xuan, Wei; Toelle, Brett G.; Webb, Karen Lucy; Almqvist, Catarina; Marks, Guy B.; Celermajer, David S.Background: n-3 Fatty acid supplementation in adults results in cardiovascular benefits. However, the cardiovascular effects of n-3 supplementation in early childhood are unknown. Objective: The objective was to evaluate blood pressure (BP) and arterial structure and function in 8-y-old children who had participated in a randomized controlled trial of dietary n-3 and n-6 modification over the first 5 y of life. Design: The children (n = 616; 49% girls) were randomly assigned antenatally to active (n = 312; increase in n-3 intake and decrease in n-6 intake) or control (n = 304) diet interventions implemented from the time of weaning or introduction of solids until 5 y of age. At age 8.0 0.1 y, BP, carotid intima-media thickness, carotid artery distensibility, augmentation index, and brachial pulse wave velocity were measured in 405 of these children. Venous blood was collected for measurement of plasma fatty acids, lipoproteins, high-sensitivity C-reactive protein, and asymmetric dimethylarginine. Plasma fatty acid concentrations were also assessed during the intervention. Results: Plasma concentrations of n-3 fatty acids were higher and of n-6 were lower in the active than in the control diet group at 18 mo and 3 and 5 y (P < 0.0001). Concentrations of n-3 and n-6 fatty acids were similar at 8 y. At 8 y of age, no significant differences were found in BP, carotid intima-media thickness, carotid artery distensibility, augmentation index, asymmetric dimethylarginine, high-sensitivity C-reactive protein, or lipoproteins between diet groups. Conclusion: A dietary supplement intervention to increase n-3 and decrease n-6 intakes from infancy until 5 y does not result in significant improvements in arterial structure and function at age 8 y. This trial was registered at the Australian Clinical Trials Registry as ACTRN012605000042640. 2009 American Society for Nutrition.
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Xu, Bei; Thornton, Charlene Eliza; Tooher, Jane M.; Ogle, Robert F.; Lim, Shirlene M.; Makris, Angela; Hennessy, AnnemarieIncreases in soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng) contribute to the pathogenesis of pre-eclampsia. Soluble Flt-1 binds to circulating free vascular endothelial growth factor and placenta growth factor and this is associated with endothelial dysfunction. Soluble endoglin, a transforming growth factor (TGF)-? coreceptor, was reported to synergize with sFlt-1 to amplify endothelial dysfunction by inhibiting TGF-?1-mediated vasorelaxation. The aim of the present study was to examine whether the antihypertensive drugs clonidine (0.08-1.3 ?g/mL), diazoxide (25-300 ?g/mL), frusemide (60-1000 ?g/mL) and hydralazine (6.3-100 ?g/mL) have any effect on placental production of sFlt-1 and sEng in placentas from normal and pre-eclamptic pregnancies. Explants were taken from non-laboured term placentas of normal pregnancy (n = 5) and women with pre-eclampsia (n = 5). Villous explants were cultured with increasing doses of antihypertensive drugs. Placental sFlt-1 and sEng production was examined using ELISA. Baseline sFlt-1 production was higher in placentas from women with pre-eclampsia than from normal pregnancy (4.5 1.4 vs 3.2 0.6 ng/mg of total protein, respectively; P < 0.001), as was sEng production (9.0 2.3 vs 4.1 0.6 ng/mg of total protein, respectively; P < 0.001). With the exception of frusemide, none of the antihypertensive drugs tested had any effect on sFlt-1 and sEng production from placental explants of normal pregnancy and women with pre-eclampsia. Increasing frusemide concentrations were correlated with increased sEng production in normal pregnancy (P < 0.005). In conclusion, placental sFlt-1 and sEng production was higher in pre-eclampsia and antihypertensive drugs had no effect on placental production of sFlt-1 and sEng in vitro. 2009 Blackwell Publishing Asia Pty Ltd.
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Rodgers, Kenneth John; Ford, Justin L.; Brunk, Ulf T.Organisms produce reactive species throughout their lives, and this may result in damage to proteins and other biological molecules. Oxidatively damaged proteins are normally selectively degraded and replaced, but this process appears to be less efficient in senescent, long-lived, postmitotic cells, as is evidenced by their accumulation in the form of lipofuscin inside the lysosomal compartment. A great deal of research has focused on changes to the proteolytic machinery in the ageing cell, in particular the proteasome, although failure of heat shock proteins (HSPs) to bind and deliver oxidised proteins efficiently to the degradation machinery could also contribute to their aggregation and accumulation. Oxidised proteins can be protease-resistant and may even directly inhibit the proteolytic machinery of the cell. The critical role that is played by HSPs in preventing accumulation of oxidised proteins is often overlooked. In this review, we examine the key role played by HSPs in recognising, removing and preventing the formation of oxidised and damaged proteins in cells. We also examine the evidence supporting the view that failure of one of these pathways could underlie ageing and age-related diseases. Finally, we discuss how modulation of HSP-activity could influence the ageing process and the progression of age-related diseases. 2009 W. S. Maney and Son Ltd.
