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Find video protocols related to scientific articles indexed in Pubmed.
Flavin containing monooxygenase 3 exerts broad effects on glucose and lipid metabolism and atherosclerosis.
J. Lipid Res.
PUBLISHED: 11-08-2014
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We performed silencing and overexpression studies of flavin containing monooxygenase 3 (FMO3) in hyperlipidemic mouse models to examine its effects on trimethylamine N-oxide (TMAO) levels and atherosclerosis. Knockdown of hepatic FMO3 in LDL receptor null (LDLRKO) mice using an antisense oligonucleotide resulted in decreased circulating TMAO levels and atherosclerosis. Surprisingly, we also observed significant decreases in hepatic lipids and in levels of plasma lipids, ketone bodies, glucose and insulin. FMO3 over-expression in transgenic mice, on the other hand, increased hepatic and plasma lipids. Global gene expression analyses suggested that these effects of FMO3 on lipogenesis and gluconeogenesis may be mediated through the PPAR? and KLF15 pathways. In vivo and in vitro results were consistent with the concept that the effects were mediated directly by FMO3 rather than TMA/TMAO; in particular, over-expression of FMO3 in the human hepatoma cell line, Hep3B, resulted in significantly increased glucose secretion and lipogenesis. Our results indicate a major role for FMO3 in modulating glucose and lipid homeostasis in vivo, and they suggest that pharmacologic inhibition of FMO3 to reduce TMAO levels would be confounded by metabolic interactions.
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Prognostic value of estimated functional capacity incremental to cardiac biomarkers in stable cardiac patients.
J Am Heart Assoc
PUBLISHED: 10-22-2014
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Few studies have investigated functional capacity self-assessment tools in either prediction of future major adverse cardiac outcomes beyond all-cause mortality or direct comparisons with clinically available biomarkers.
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The contributory role of gut microbiota in cardiovascular disease.
J. Clin. Invest.
PUBLISHED: 10-01-2014
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Our group recently discovered that certain dietary nutrients possessing a trimethylamine (TMA) moiety, namely choline/phosphatidylcholine and L-carnitine, participate in the development of atherosclerotic heart disease. A meta-organismal pathway was elucidated involving gut microbiota-dependent formation of TMA and host hepatic flavin monooxygenase 3-dependent (FMO3-dependent) formation of TMA-N-oxide (TMAO), a metabolite shown to be both mechanistically linked to atherosclerosis and whose levels are strongly linked to cardiovascular disease (CVD) risks. Collectively, these studies reveal that nutrient precursors, gut microbiota, and host participants along the meta-organismal pathway elucidated may serve as new targets for the prevention and treatment of CVD.
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Dual Role of the Leukocyte Integrin ?M?2 in Angiogenesis.
J. Immunol.
PUBLISHED: 09-26-2014
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Polymorphonuclear neutrophils (PMNs) and macrophages are crucial contributors to neovascularization, serving as a source of chemokines, growth factors, and proteases. ?M?2(CD11b/CD18) and ?L?2(CD11a/CD18) are expressed prominently and have been implicated in various responses of these cell types. Thus, we investigated the role of these ?2 integrins in angiogenesis. Angiogenesis was analyzed in wild-type (WT), ?M-knockout (?M (-/-)), and ?L-deficient (?L (-/-)) mice using B16F10 melanoma, RM1 prostate cancer, and Matrigel implants. In all models, vascular area was decreased by 50-70% in ?M (-/-) mice, resulting in stunted tumor growth as compared with WT mice. In contrast, ?L deficiency did not impair angiogenesis and tumor growth. The neovessels in ?M (-/-) mice were leaky and immature because they lacked smooth muscle cell and pericytes. Defective angiogenesis in the ?M (-/-) mice was associated with attenuated PMN and macrophage recruitment into tumors. In contrast to WT or the ?L (-/-) leukocytes, the ?M (-/-) myeloid cells showed impaired plasmin (Plm)-dependent extracellular matrix invasion, resulting from 50-75% decrease in plasminogen (Plg) binding and pericellular Plm activity. Surface plasmon resonance verified direct interaction of the ?MI-domain, the major ligand binding site in the ?2 integrins, with Plg. However, the ?LI-domain failed to bind Plg. In addition, endothelial cells failed to form tubes in the presence of conditioned medium collected from TNF-?-stimulated PMNs derived from the ?M (-/-) mice because of severely impaired degranulation and secretion of VEGF. Thus, ?M?2 plays a dual role in angiogenesis, supporting not only Plm-dependent recruitment of myeloid cells to angiogenic niches, but also secretion of VEGF by these cells.
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Prognostic Value of Estimating Functional Capacity Using the Duke Activity Status Index in Stable Patients with Chronic Heart Failure.
J. Card. Fail.
PUBLISHED: 08-28-2014
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Over the years several methods have been developed to reliably quantify functional capacity in patients with heart failure. Few studies have investigated the prognostic value of these assessment tools beyond cardio-renal prognostic biomarkers in stable patients with chronic heart failure.
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Prognostic Value of Elevated Serum Ceruloplasmin Levels in Patients with Heart Failure.
J. Card. Fail.
PUBLISHED: 08-13-2014
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Ceruloplasmin (Cp) is a copper-binding acute-phase protein that is increased in inflammatory states and deficient in Wilson's disease. Recent studies demonstrate increased levels of Cp are associated with increased risk of developing heart failure. Our objective is to test the hypothesis that serum Cp provides incremental and independent prediction of survival in stable patients with heart failure.
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Integrative genomics reveals novel molecular pathways and gene networks for coronary artery disease.
PLoS Genet.
PUBLISHED: 07-01-2014
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The majority of the heritability of coronary artery disease (CAD) remains unexplained, despite recent successes of genome-wide association studies (GWAS) in identifying novel susceptibility loci. Integrating functional genomic data from a variety of sources with a large-scale meta-analysis of CAD GWAS may facilitate the identification of novel biological processes and genes involved in CAD, as well as clarify the causal relationships of established processes. Towards this end, we integrated 14 GWAS from the CARDIoGRAM Consortium and two additional GWAS from the Ottawa Heart Institute (25,491 cases and 66,819 controls) with 1) genetics of gene expression studies of CAD-relevant tissues in humans, 2) metabolic and signaling pathways from public databases, and 3) data-driven, tissue-specific gene networks from a multitude of human and mouse experiments. We not only detected CAD-associated gene networks of lipid metabolism, coagulation, immunity, and additional networks with no clear functional annotation, but also revealed key driver genes for each CAD network based on the topology of the gene regulatory networks. In particular, we found a gene network involved in antigen processing to be strongly associated with CAD. The key driver genes of this network included glyoxalase I (GLO1) and peptidylprolyl isomerase I (PPIL1), which we verified as regulatory by siRNA experiments in human aortic endothelial cells. Our results suggest genetic influences on a diverse set of both known and novel biological processes that contribute to CAD risk. The key driver genes for these networks highlight potential novel targets for further mechanistic studies and therapeutic interventions.
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Oxido-reductive regulation of vascular remodeling by receptor tyrosine kinase ROS1.
J. Clin. Invest.
PUBLISHED: 06-09-2014
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Angioplasty and stenting is the primary treatment for flow-limiting atherosclerosis; however, this strategy is limited by pathological vascular remodeling. Using a systems approach, we identified a role for the network hub gene glutathione peroxidase-1 (GPX1) in pathological remodeling following human blood vessel stenting. Constitutive deletion of Gpx1 in atherosclerotic mice recapitulated this phenotype of increased vascular smooth muscle cell (VSMC) proliferation and plaque formation. In an independent patient cohort, gene variant pair analysis identified an interaction of GPX1 with the orphan protooncogene receptor tyrosine kinase ROS1. A meta-analysis of the only genome-wide association studies of human neointima-induced in-stent stenosis confirmed the association of the ROS1 variant with pathological remodeling. Decreased GPX1 expression in atherosclerotic mice led to reductive stress via a time-dependent increase in glutathione, corresponding to phosphorylation of the ROS1 kinase activation site Y2274. Loss of GPX1 function was associated with both oxidative and reductive stress, the latter driving ROS1 activity via s-glutathiolation of critical residues of the ROS1 tyrosine phosphatase SHP-2. ROS1 inhibition with crizotinib and deglutathiolation of SHP-2 abolished GPX1-mediated increases in VSMC proliferation while leaving endothelialization intact. Our results indicate that GPX1-dependent alterations in oxido-reductive stress promote ROS1 activation and mediate vascular remodeling.
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MyD88-dependent interplay between myeloid and endothelial cells in the initiation and progression of obesity-associated inflammatory diseases.
J. Exp. Med.
PUBLISHED: 04-21-2014
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Low-grade systemic inflammation is often associated with metabolic syndrome, which plays a critical role in the development of the obesity-associated inflammatory diseases, including insulin resistance and atherosclerosis. Here, we investigate how Toll-like receptor-MyD88 signaling in myeloid and endothelial cells coordinately participates in the initiation and progression of high fat diet-induced systemic inflammation and metabolic inflammatory diseases. MyD88 deficiency in myeloid cells inhibits macrophage recruitment to adipose tissue and their switch to an M1-like phenotype. This is accompanied by substantially reduced diet-induced systemic inflammation, insulin resistance, and atherosclerosis. MyD88 deficiency in endothelial cells results in a moderate reduction in diet-induced adipose macrophage infiltration and M1 polarization, selective insulin sensitivity in adipose tissue, and amelioration of spontaneous atherosclerosis. Both in vivo and ex vivo studies suggest that MyD88-dependent GM-CSF production from the endothelial cells might play a critical role in the initiation of obesity-associated inflammation and development of atherosclerosis by priming the monocytes in the adipose and arterial tissues to differentiate into M1-like inflammatory macrophages. Collectively, these results implicate a critical MyD88-dependent interplay between myeloid and endothelial cells in the initiation and progression of obesity-associated inflammatory diseases.
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Comparative genome-wide association studies in mice and humans for trimethylamine N-oxide, a proatherogenic metabolite of choline and L-carnitine.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 03-27-2014
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Elevated levels of plasma trimethylamine N-oxide (TMAO), the product of gut microbiome and hepatic-mediated metabolism of dietary choline and L-carnitine, have recently been identified as a novel risk factor for the development of atherosclerosis in mice and humans. The goal of this study was to identify the genetic factors associated with plasma TMAO levels.
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Measurement of trimethylamine-N-oxide by stable isotope dilution liquid chromatography tandem mass spectrometry.
Anal. Biochem.
PUBLISHED: 03-23-2014
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Trimethylamine-N-oxide (TMAO) levels in blood predict future risk for major adverse cardiac events including myocardial infarction, stroke, and death. Thus, the rapid determination of circulating TMAO concentration is of clinical interest. Here we report a method to measure TMAO in biological matrices by stable isotope dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) with lower and upper limits of quantification of 0.05 and >200?M, respectively. Spike and recovery studies demonstrate an accuracy at low (0.5?M), mid (5?M), and high (100?M) levels of 98.2, 97.3, and 101.6%, respectively. Additional assay performance metrics include intraday and interday coefficients of variance of <6.4 and <9.9%, respectively, across the range of TMAO levels. Stability studies reveal that TMAO in plasma is stable both during storage at -80°C for 5years and to multiple freeze thaw cycles. Fasting plasma normal range studies among apparently healthy subjects (n=349) show a range of 0.73-126?M, median (interquartile range) levels of 3.45 (2.25-5.79)?M, and increasing values with age. The LC/MS/MS-based assay reported should be of value for further studies evaluating TMAO as a risk marker and for examining the effect of dietary, pharmacologic, and environmental factors on TMAO levels.
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Cancer stem cell-specific scavenger receptor 36 drives glioblastoma progression.
Stem Cells
PUBLISHED: 03-14-2014
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Glioblastoma (GBM) contains a self-renewing, tumorigenic cancer stem cell (CSC) population which contributes to tumor propagation and therapeutic resistance. While the tumor microenvironment is essential to CSC self-renewal, the mechanisms by which CSCs sense and respond to microenvironmental conditions are poorly understood. Scavenger receptors are a broad class of membrane receptors well characterized on immune cells and instrumental in sensing apoptotic cellular debris and modified lipids. Here, we provide evidence that CSCs selectively use the scavenger receptor CD36 to promote their maintenance using patient-derived CSCs and in vivo xenograft models. CD36 expression was observed in GBM cells in addition to previously described cell types including endothelial cells, macrophages, and microglia. CD36 was enriched in CSCs and was able to functionally distinguish self-renewing cells. CD36 was coexpressed with integrin alpha 6 and CD133, previously described CSC markers, and CD36 reduction resulted in concomitant loss of integrin alpha 6 expression, self-renewal, and tumor initiation capacity. We confirmed oxidized phospholipids, ligands of CD36, were present in GBM and found that the proliferation of CSCs, but not non-CSCs, increased with exposure to oxidized low-density lipoprotein. CD36 was an informative biomarker of malignancy and negatively correlated to patient prognosis. These results provide a paradigm for CSCs to thrive by the selective enhanced expression of scavenger receptors, providing survival, and metabolic advantages.
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Site-specific nitration of apolipoprotein A-I at tyrosine 166 is both abundant within human atherosclerotic plaque and dysfunctional.
J. Biol. Chem.
PUBLISHED: 02-20-2014
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We reported previously that apolipoprotein A-I (apoA-I) is oxidatively modified in the artery wall at tyrosine 166 (Tyr(166)), serving as a preferred site for post-translational modification through nitration. Recent studies, however, question the extent and functional importance of apoA-I Tyr(166) nitration based upon studies of HDL-like particles recovered from atherosclerotic lesions. We developed a monoclonal antibody (mAb 4G11.2) that recognizes, in both free and HDL-bound forms, apoA-I harboring a 3-nitrotyrosine at position 166 apoA-I (NO2-Tyr(166)-apoA-I) to investigate the presence, distribution, and function of this modified apoA-I form in atherosclerotic and normal artery wall. We also developed recombinant apoA-I with site-specific 3-nitrotyrosine incorporation only at position 166 using an evolved orthogonal nitro-Tyr-aminoacyl-tRNA synthetase/tRNACUA pair for functional studies. Studies with mAb 4G11.2 showed that NO2-Tyr(166)-apoA-I was easily detected in atherosclerotic human coronary arteries and accounted for ? 8% of total apoA-I within the artery wall but was nearly undetectable (>100-fold less) in normal coronary arteries. Buoyant density ultracentrifugation analyses showed that NO2-Tyr(166)-apoA-I existed as a lipid-poor lipoprotein with <3% recovered within the HDL-like fraction (d = 1.063-1.21). NO2-Tyr(166)-apoA-I in plasma showed a similar distribution. Recovery of NO2-Tyr(166)-apoA-I using immobilized mAb 4G11.2 showed an apoA-I form with 88.1 ± 8.5% reduction in lecithin-cholesterol acyltransferase activity, a finding corroborated using a recombinant apoA-I specifically designed to include the unnatural amino acid exclusively at position 166. Thus, site-specific nitration of apoA-I at Tyr(166) is an abundant modification within the artery wall that results in selective functional impairments. Plasma levels of this modified apoA-I form may provide insights into a pathophysiological process within the diseased artery wall.
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Prognostic value of choline and betaine depends on intestinal microbiota-generated metabolite trimethylamine-N-oxide.
Eur. Heart J.
PUBLISHED: 02-03-2014
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Recent metabolomics and animal model studies show trimethylamine-N-oxide (TMAO), an intestinal microbiota-dependent metabolite formed from dietary trimethylamine-containing nutrients such as phosphatidylcholine (PC), choline, and carnitine, is linked to coronary artery disease pathogenesis. Our aim was to examine the prognostic value of systemic choline and betaine levels in stable cardiac patients.
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Myeloperoxidase levels predict accelerated progression of coronary atherosclerosis in diabetic patients: insights from intravascular ultrasound.
Atherosclerosis
PUBLISHED: 01-29-2014
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While inflammation has been proposed to contribute to the adverse cardiovascular outcome in diabetic patients, the specific pathways involved have not been elucidated. The leukocyte derived product, myeloperoxidase (MPO), has been implicated in all stages of atherosclerosis. The relationship between MPO and accelerated disease progression observed in diabetic patients has not been studied.
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An abundant dysfunctional apolipoprotein A1 in human atheroma.
Nat. Med.
PUBLISHED: 01-26-2014
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Recent studies have indicated that high-density lipoproteins (HDLs) and their major structural protein, apolipoprotein A1 (apoA1), recovered from human atheroma are dysfunctional and are extensively oxidized by myeloperoxidase (MPO). In vitro oxidation of either apoA1 or HDL particles by MPO impairs their cholesterol acceptor function. Here, using phage display affinity maturation, we developed a high-affinity monoclonal antibody that specifically recognizes both apoA1 and HDL that have been modified by the MPO-H2O2-Cl(-) system. An oxindolyl alanine (2-OH-Trp) moiety at Trp72 of apoA1 is the immunogenic epitope. Mutagenesis studies confirmed a critical role for apoA1 Trp72 in MPO-mediated inhibition of the ATP-binding cassette transporter A1 (ABCA1)-dependent cholesterol acceptor activity of apoA1 in vitro and in vivo. ApoA1 containing a 2-OH-Trp72 group (oxTrp72-apoA1) is in low abundance within the circulation but accounts for 20% of the apoA1 in atherosclerosis-laden arteries. OxTrp72-apoA1 recovered from human atheroma or plasma is lipid poor, virtually devoid of cholesterol acceptor activity and demonstrated both a potent proinflammatory activity on endothelial cells and an impaired HDL biogenesis activity in vivo. Elevated oxTrp72-apoA1 levels in subjects presenting to a cardiology clinic (n = 627) were associated with increased cardiovascular disease risk. Circulating oxTrp72-apoA1 levels may serve as a way to monitor a proatherogenic process in the artery wall.
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Effects of native and myeloperoxidase-modified apolipoprotein a-I on reverse cholesterol transport and atherosclerosis in mice.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 01-09-2014
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Preclinical and clinical studies have shown beneficial effects of infusions of apolipoprotein A-I (ApoA-I) on atherosclerosis. ApoA-I is also a target for myeloperoxidase-mediated oxidation, leading in vitro to a loss of its ability to promote ATP-binding cassette transporter A1-dependent macrophage cholesterol efflux. Therefore, we hypothesized that myeloperoxidase-mediated ApoA-I oxidation would impair its promotion of reverse cholesterol transport in vivo and the beneficial effects on atherosclerotic plaques.
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OxNASH score correlates with histologic features and severity of nonalcoholic fatty liver disease.
Dig. Dis. Sci.
PUBLISHED: 01-07-2014
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Oxidative stress is a core abnormality responsible for disease progression in nonalcoholic fatty liver disease (NAFLD). By employing a highly sensitive liquid chromatography-tandem mass spectrometry (LC/MS/MS) approach we recently were able to define the circulating profile of bioactive lipid peroxidation products characteristic of patients with nonalcoholic steatohepatitis (NASH) and developed the OxNASH score for NASH diagnosis. The aims of this study were to assess the utility of OxNASH as a predictor of NASH and study the association between OxNASH and specific histologic features of NAFLD.
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Usefulness of elevated urine neopterin levels in assessing cardiac dysfunction and exercise ventilation inefficiency in patients with chronic systolic heart failure.
Am. J. Cardiol.
PUBLISHED: 01-04-2014
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Neopterin is synthesized by macrophages upon stimulation with gamma-interferon, and high neopterin production is associated with cellular immune activation and increased production of reactive oxygen species (oxidant stress), but the clinical utility of urine neopterin levels in patients with heart failure (HF) has not been explored. Fifty-three ambulatory patients with chronic systolic HF (left ventricular [LV] ejection fraction ?40%) underwent comprehensive echocardiographic evaluation and cardiopulmonary exercise testing. Urine neopterin levels were quantified by liquid chromatography with tandem mass spectrometric analyses and corrected to urine creatinine (Cr) levels. In our study cohort, median urine neopterin level was 60 ?mol/mol Cr (interquartile range 40 to 86). There were modest correlations between urine neopterin levels and abnormalities in cardiac structure and function by echocardiography: LV ejection fraction (r = -0.33, p = 0.017), indexed LV end-diastolic volume (r = 0.31, p = 0.029), indexed LV end-systolic volume (r = 0.32, p = 0.024), and E/septal Ea (r = 0.28, p = 0.041). Although there was no significant correlation between urine neopterin and maximal oxygen uptake (peak VO2: r = -0.25, p = 0.07), there was a modest correlation between urine neopterin and maximal ventilation/carbon dioxide production ratio (VE/VCO2 max: r = 0.38, p = 0.005). In conclusion, increase in urine neopterin levels tracks with disease severity in patients with chronic systolic HF.
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High-density lipoprotein and atherosclerosis regression: evidence from preclinical and clinical studies.
Circ. Res.
PUBLISHED: 01-04-2014
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High-density lipoprotein (HDL) particles transport (among other molecules) cholesterol (HDL-C). In epidemiological studies, plasma HDL-C levels have an inverse relationship to the risk of atherosclerotic cardiovascular disease. It has been assumed that this reflects the protective functions of HDL, which include their ability to promote cholesterol efflux. Yet, several recent pharmacological and genetic studies have failed to demonstrate that increased plasma levels of HDL-C resulted in decreased cardiovascular disease risk, giving rise to a controversy regarding whether plasma levels of HDL-C reflect HDL function, or that HDL is even as protective as assumed. The evidence from preclinical and (limited) clinical studies shows that HDL can promote the regression of atherosclerosis when the levels of functional particles are increased from endogenous or exogenous sources. The data show that regression results from a combination of reduced plaque lipid and macrophage contents, as well as from a reduction in its inflammatory state. Although more research will be needed regarding basic mechanisms and to establish that these changes translate clinically to reduced cardiovascular disease events, that HDL can regress plaques suggests that the recent trial failures do not eliminate HDL from consideration as an atheroprotective agent but rather emphasizes the important distinction between HDL function and plasma levels of HDL-C.
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Effect of plasma uric acid on antioxidant capacity, oxidative stress, and insulin sensitivity in obese subjects.
Diabetes
PUBLISHED: 12-18-2013
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Oxidative stress is purported to be involved in the pathogenesis of obesity-associated insulin resistance. We evaluated whether alterations in circulating uric acid (UA), a systemic antioxidant, affects: 1) systemic (plasma and saliva) non-enzimatic antioxidant capacity (NEAC); 2) markers of systemic (urinary 8-iso-prostaglandin-F2?) and muscle (carbonylated protein content) oxidative stress; and 3) whole-body insulin sensitivity (% increase in glucose uptake during a hyperinsulinemic-euglycemic clamp procedure). Thirty-one obese subjects (BMI 37.1±0.7 kg/m(2)) with either high serum UA (HUA, 7.1±0.4 mg/dL; n=15) or normal serum UA (NUA, 4.5±0.2 mg/dL; n=16) were studied; 13 subjects with HUA were studied again after reduction of serum UA to 0 by infusing a recombinant urate oxidase. HUA subjects had 20-90% greater NEAC, but lower insulin sensitivity (40%) and markers of oxidative stress (30%) than subjects in the NUA group (all P<0.05). Acute UA reduction caused a 45-95% decrease in NEAC and a 25-40% increase in systemic and muscle markers of oxidative stress (all P<0.05), but did not affect insulin sensitivity (from 168±25% to 156±17%, P=NS). These results demonstrate that circulating UA is a major antioxidant, and might help protect against free-radical oxidative damage. However, oxidative stress is not a major determinant of insulin action in vivo.
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Plasma Ceruloplasmin, a Regulator of Nitric Oxide Activity, and Incident Cardiovascular Risk in Patients with CKD.
Clin J Am Soc Nephrol
PUBLISHED: 12-05-2013
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Increased serum levels of the acute-phase reactant ceruloplasmin predict adverse clinical outcomes in the setting of acute coronary syndromes and heart failure, but their role in patients with CKD is unclear. This study investigated the relationship of ceruloplasmin with clinical outcomes in CKD, especially with regard to traditional cardiac biomarkers.
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Sphingomyelin depletion impairs anionic phospholipid inward translocation and induces cholesterol efflux.
J. Biol. Chem.
PUBLISHED: 11-12-2013
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The phosphatidylserine (PS) floppase activity (outward translocation) of ABCA1 leads to plasma membrane remodeling that plays a role in lipid efflux to apolipoprotein A-I (apoAI) generating nascent high density lipoprotein. The Tangier disease W590S ABCA1 mutation has defective PS floppase activity and diminished cholesterol efflux activity. Here, we report that depletion of sphingomyelin by inhibitors or sphingomyelinase caused plasma membrane remodeling, leading to defective flip (inward translocation) of PS, higher PS exposure, and higher cholesterol efflux from cells by both ABCA1-dependent and ABCA1-independent mechanisms. Mechanistically, sphingomyelin was connected to PS translocation in cell-free liposome studies that showed that sphingomyelin increased the rate of spontaneous PS flipping. Depletion of sphingomyelin in stably transfected HEK293 cells expressing the Tangier disease W590S mutant ABCA1 isoform rescued the defect in PS exposure and restored cholesterol efflux to apoAI. Liposome studies showed that PS directly increased cholesterol accessibility to extraction by cyclodextrin, providing the mechanistic link between cell surface PS and cholesterol efflux. We conclude that altered plasma membrane environment conferred by depleting sphingomyelin impairs PS flip and promotes cholesterol efflux in ABCA1-dependent and -independent manners.
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The susceptibility of bioprosthetic heart valve leaflets to oxidation.
Biomaterials
PUBLISHED: 10-24-2013
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The clinical use of bioprosthetic heart valves (BHV) is limited due to device failure caused by structural degeneration of BHV leaflets. In this study we investigated the hypothesis that oxidative stress contributes to this process. Fifteen clinical BHV that had been removed for device failure were analyzed for oxidized amino acids using mass spectrometry. Significantly increased levels of ortho-tyrosine, meta-tyrosine and dityrosine were present in clinical BHV explants as compared to the non-implanted BHV material glutaraldehyde treated bovine pericardium (BP). BP was exposed in vitro to oxidizing conditions (FeSO4/H2O2) to assess the effects of oxidation on structural degeneration. Exposure to oxidizing conditions resulted in significant collagen deterioration, loss of glutaraldehyde cross-links, and increased susceptibility to collagenase degradation. BP modified through covalent attachment of the oxidant scavenger 3-(4-hydroxy-3,5-di-tert-butylphenyl) propyl amine (DBP) was resistant to all of the monitored parameters of structural damage induced by oxidation. These results indicate that oxidative stress, particularly via hydroxyl radical and tyrosyl radical mediated pathways, may be involved in the structural degeneration of BHV, and that this mechanism may be attenuated through local delivery of antioxidants such as DBP.
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Function and distribution of apolipoprotein A1 in the artery wall are markedly distinct from those in plasma.
Circulation
PUBLISHED: 08-22-2013
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Prior studies show that apolipoprotein A1 (apoA1) recovered from human atherosclerotic lesions is highly oxidized. Ex vivo oxidation of apoA1 or high-density lipoprotein (HDL) cross-links apoA1 and impairs lipid binding, cholesterol efflux, and lecithin-cholesterol acyltransferase activities of the lipoprotein. Remarkably, no studies to date directly quantify either the function or HDL particle distribution of apoA1 recovered from the human artery wall.
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Kindlin-2 regulates hemostasis by controlling endothelial cell-surface expression of ADP/AMP catabolic enzymes via a clathrin-dependent mechanism.
Blood
PUBLISHED: 07-29-2013
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Kindlin-2, a widely distributed cytoskeletal protein, has been implicated in integrin activation, and its absence is embryonically lethal in mice. In the present study, we tested whether hemostasis might be perturbed in kindlin-2(+/-) mice. Bleeding time and carotid artery occlusion time were significantly prolonged in kindlin-2(+/-) mice. Whereas plasma concentrations/activities of key coagulation/fibrinolytic proteins and platelet counts and aggregation were similar in wild-type and kindlin-2(+/-) mice, kindlin-2(+/-) endothelial cells (ECs) showed enhanced inhibition of platelet aggregation induced by adenosine 5-diphosphate (ADP) or low concentrations of other agonists. Cell-surface expression of 2 enzymes involved in ADP/adenosine 5-monophosphate (AMP) degradation, adenosine triphosphate (ATP) diphosphohydrolase (CD39) and ecto-5-nucleotidase (CD73) were increased twofold to threefold on kindlin-2(+/-) ECs, leading to enhanced ATP/ADP catabolism and production of adenosine, an inhibitor of platelet aggregation. Trafficking of CD39 and CD73 at the EC surface was altered in kindlin-2(+/-) mice. Mechanistically, this was attributed to direct interaction of kindlin-2 with clathrin heavy chain, thereby controlling endocytosis and recycling of CD39 and CD73. The interaction of kindlin-2 with clathrin was independent of its integrin binding site but still dependent on a site within its F3 subdomain. Thus, kindlin-2 regulates trafficking of EC surface enzymes that control platelet responses and hemostasis.
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Ceruloplasmin and heart failure in the Atherosclerosis Risk in Communities study.
Circ Heart Fail
PUBLISHED: 07-16-2013
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Ceruloplasmin (Cp) decreases nitric oxide bioavailability in blood and has been associated with cardiovascular disease (CVD) in clinical studies. We assessed the associations between Cp and incident heart failure (HF), death, and CVD in the Atherosclerosis Risk in Communities (ARIC) study.
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2H2O-based high-density lipoprotein turnover method for the assessment of dynamic high-density lipoprotein function in mice.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 06-13-2013
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High-density lipoprotein (HDL) promotes reverse cholesterol transport from peripheral tissues to the liver for clearance. Reduced HDL-cholesterol (HDLc) is associated with atherosclerosis; however, as a predictor of cardiovascular disease, HDLc has limitations because it is not a direct marker of HDL functionality. Our objective was to develop a mass spectrometry-based method for the simultaneous measurement of HDLc and ApoAI kinetics in mice, using a single (2)H2O tracer, and use it to examine genetic and drug perturbations on HDL turnover in vivo.
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Two chromosome 9p21 haplotype blocks distinguish between coronary artery disease and myocardial infarction risk.
Circ Cardiovasc Genet
PUBLISHED: 05-31-2013
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Variants at the 9p21 locus associate with the risk of coronary artery disease (CAD) or myocardial infarction (MI). However, atherosclerotic plaque deposition is distinct from MI (plaque rupture and thrombosis), and recent studies showed no association between these variants and MI in patients with preexisting CAD. We performed haplotype analysis at the 9p21 locus to test whether haplotypes at distinct linkage disequilibrium blocks predict these phenotypes.
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Myeloperoxidase, paraoxonase-1, and HDL form a functional ternary complex.
J. Clin. Invest.
PUBLISHED: 05-23-2013
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Myeloperoxidase (MPO) and paraoxonase 1 (PON1) are high-density lipoprotein-associated (HDL-associated) proteins mechanistically linked to inflammation, oxidant stress, and atherosclerosis. MPO is a source of ROS during inflammation and can oxidize apolipoprotein A1 (APOA1) of HDL, impairing its atheroprotective functions. In contrast, PON1 fosters systemic antioxidant effects and promotes some of the atheroprotective properties attributed to HDL. Here, we demonstrate that MPO, PON1, and HDL bind to one another, forming a ternary complex, wherein PON1 partially inhibits MPO activity, while MPO inactivates PON1. MPO oxidizes PON1 on tyrosine 71 (Tyr71), a modified residue found in human atheroma that is critical for HDL binding and PON1 function. Acute inflammation model studies with transgenic and knockout mice for either PON1 or MPO confirmed that MPO and PON1 reciprocally modulate each others function in vivo. Further structure and function studies identified critical contact sites between APOA1 within HDL, PON1, and MPO, and proteomics studies of HDL recovered from acute coronary syndrome (ACS) subjects revealed enhanced chlorotyrosine content, site-specific PON1 methionine oxidation, and reduced PON1 activity. HDL thus serves as a scaffold upon which MPO and PON1 interact during inflammation, whereupon PON1 binding partially inhibits MPO activity, and MPO promotes site-specific oxidative modification and impairment of PON1 and APOA1 function.
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The cardioprotective protein apolipoprotein A1 promotes potent anti-tumorigenic effects.
J. Biol. Chem.
PUBLISHED: 05-17-2013
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Here, we show that apolipoprotein A1 (apoA1), the major protein component of high density lipoprotein (HDL), through both innate and adaptive immune processes, potently suppresses tumor growth and metastasis in multiple animal tumor models, including the aggressive B16F10L murine malignant melanoma model. Mice expressing the human apoA1 transgene (A1Tg) exhibited increased infiltration of CD11b(+) F4/80(+) macrophages with M1, anti-tumor phenotype, reduced tumor burden and metastasis, and enhanced survival. In contrast, apoA1-deficient (A1KO) mice showed markedly heightened tumor growth and reduced survival. Injection of human apoA1 into A1KO mice inoculated with tumor cells remarkably reduced both tumor growth and metastasis, enhanced survival, and promoted regression of both tumor and metastasis burden when administered following palpable tumor formation and metastasis development. Studies with apolipoprotein A2 revealed the anti-cancer therapeutic effect was specific to apoA1. In vitro studies ruled out substantial direct suppressive effects by apoA1 or HDL on tumor cells. Animal models defective in different aspects of immunity revealed both innate and adaptive arms of immunity contribute to complete apoA1 anti-tumor activity. This study reveals a potent immunomodulatory role for apoA1 in the tumor microenvironment, altering tumor-associated macrophages from a pro-tumor M2 to an anti-tumor M1 phenotype. Use of apoA1 to redirect in vivo elicited tumor-infiltrating macrophages toward tumor rejection may hold benefit as a potential cancer therapeutic.
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Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk.
N. Engl. J. Med.
PUBLISHED: 04-26-2013
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Recent studies in animals have shown a mechanistic link between intestinal microbial metabolism of the choline moiety in dietary phosphatidylcholine (lecithin) and coronary artery disease through the production of a proatherosclerotic metabolite, trimethylamine-N-oxide (TMAO). We investigated the relationship among intestinal microbiota-dependent metabolism of dietary phosphatidylcholine, TMAO levels, and adverse cardiovascular events in humans.
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Genome-wide and gene-centric analyses of circulating myeloperoxidase levels in the charge and care consortia.
Hum. Mol. Genet.
PUBLISHED: 04-24-2013
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Increased systemic levels of myeloperoxidase (MPO) are associated with the risk of coronary artery disease (CAD). To identify the genetic factors that are associated with circulating MPO levels, we carried out a genome-wide association study (GWAS) and a gene-centric analysis in subjects of European ancestry and African Americans (AAs). A locus on chromosome 1q31.1 containing the complement factor H (CFH) gene was strongly associated with serum MPO levels in 9305 subjects of European ancestry (lead SNP rs800292; P = 4.89 × 10(-41)) and in 1690 AA subjects (rs505102; P = 1.05 × 10(-8)). Gene-centric analyses in 8335 subjects of European ancestry additionally identified two rare MPO coding sequence variants that were associated with serum MPO levels (rs28730837, P = 5.21 × 10(-12); rs35897051, P = 3.32 × 10(-8)). A GWAS for plasma MPO levels in 9260 European ancestry subjects identified a chromosome 17q22 region near MPO that was significantly associated (lead SNP rs6503905; P = 2.94 × 10(-12)), but the CFH locus did not exhibit evidence of association with plasma MPO levels. Functional analyses revealed that rs800292 was associated with levels of complement proteins in serum. Variants at chromosome 17q22 also had pleiotropic cis effects on gene expression. In a case-control analysis of ?80 000 subjects from CARDIoGRAM, none of the identified single-nucleotide polymorphisms (SNPs) were associated with CAD. These results suggest that distinct genetic factors regulate serum and plasma MPO levels, which may have relevance for various acute and chronic inflammatory disorders. The clinical implications for CAD and a better understanding of the functional basis for the association of CFH and MPO variants with circulating MPO levels require further study.
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Diminished antioxidant activity of high-density lipoprotein-associated proteins in chronic kidney disease.
J Am Heart Assoc
PUBLISHED: 04-06-2013
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Decreased serum arylesterase activity, catalyzed by the high-density lipoprotein-associated paraoxonase (PON)-1, is associated with increased oxidant stress and atherosclerosis risk. We sought to determine the prognostic value of serum PON-1 activity, as monitored by PON or arylesterase activities, in subjects with chronic kidney disease (CKD), particularly in relation to established cardiac biomarkers.
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ABCA1 mediates unfolding of apolipoprotein AI N terminus on the cell surface before lipidation and release of nascent high-density lipoprotein.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 04-04-2013
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To gain insight into the mechanism by which ABCA1 generates nascent high-density lipoprotein.
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Paradoxical association of enhanced cholesterol efflux with increased incident cardiovascular risks.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 03-21-2013
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Diminished cholesterol efflux activity of apolipoprotein B (apoB)-depleted serum is associated with prevalent coronary artery disease, but its prognostic value for incident cardiovascular events is unclear. We investigated the relationship of cholesterol efflux activity with both prevalent coronary artery disease and incident development of major adverse cardiovascular events (death, myocardial infarction, or stroke).
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Aspirin hydrolysis in plasma is a variable function of butyrylcholinesterase and platelet-activating factor acetylhydrolase 1b2 (PAFAH1b2).
J. Biol. Chem.
PUBLISHED: 03-18-2013
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Aspirin is rapidly hydrolyzed within erythrocytes by a heterodimer of PAFAH1b2/PAFAH1b3 but also in plasma by an unidentified activity. Hydrolysis in both compartments was variable, with a 12-fold variation in plasma among 2226 Cleveland Clinic GeneBank patients. Platelet inhibition by aspirin was suppressed in plasma that rapidly hydrolyzed aspirin. Plasma aspirin hydrolysis was significantly higher in patients with coronary artery disease compared with control subjects (16.5 ± 4.4 versus 15.1 ± 3.7 nmol/ml/min; p = 3.4 × 10(-8)). A genome-wide association study of 2054 GeneBank subjects identified a single locus immediately adjacent to the BCHE (butyrylcholinesterase) gene associated with plasma aspirin hydrolytic activity (lead SNP, rs6445035; p = 9.1 × 10(-17)). However, its penetrance was low, and plasma from an individual with an inactivating mutation in BCHE still effectively hydrolyzed aspirin. A second aspirin hydrolase was identified in plasma, the purification of which showed it to be homomeric PAFAH1b2. This is distinct from the erythrocyte PAFAH1b2/PAFAH1b3 heterodimer. Inhibitors showed that both butyrylcholinesterase (BChE) and PAFAH1b2 contribute to aspirin hydrolysis in plasma, with variation primarily reflecting non-genetic variation of BChE activity. Therefore, aspirin is hydrolyzed in plasma by two enzymes, BChE and a new extracellular form of platelet-activating factor acetylhydrolase, PAFAH1b2. Hydrolytic effectiveness varies widely primarily from non-genetic variation of BChE activity that affects aspirin bioavailability in blood and the ability of aspirin to inhibit platelet aggregation.
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Quantification of fatty acid oxidation products using online high-performance liquid chromatography tandem mass spectrometry.
Free Radic. Biol. Med.
PUBLISHED: 02-28-2013
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Oxidized fatty acids formed via lipid peroxidation are implicated in pathological processes such as inflammation and atherosclerosis. A number of methods may be used to detect specific oxidized fatty acids containing a single or multiple combinations of epoxide, hydroxyl, ketone, and hydroperoxide moieties on varying carbon chain lengths from C8 up to C30. Some of these methods are nonspecific and their use in biological systems is fraught with difficulty. Measures of specific oxidized fatty acid derivatives help in identifying oxidation pathways in pathological processes. We used liquid chromatography coupled with electrospray ionization tandem mass spectrometry as an efficient, selective, and sensitive method for identifying and analyzing multiple specific fatty acid peroxidation products in human plasma and other biological matrices. We then distilled the essential components of a number of these analyses to provide an efficient protocol by which fatty acid oxidation products and their parent compounds can be determined. In this protocol, addition of a synthetic internal standard to the sample, followed by base hydrolysis at elevated temperature and liquid-liquid phase sample extraction with lighter-than-water solvents, facilitates isolation of the oxidized fatty acid species. These species can be identified and accurately quantified using stable-isotope dilution and multiple-reaction monitoring. Use of a coupled multiplexed gradient HPLC system on the front end enables high-throughput chromatography and more efficient use of mass spectrometer time.
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Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis.
Nat. Med.
PUBLISHED: 02-27-2013
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Intestinal microbiota metabolism of choline and phosphatidylcholine produces trimethylamine (TMA), which is further metabolized to a proatherogenic species, trimethylamine-N-oxide (TMAO). We demonstrate here that metabolism by intestinal microbiota of dietary L-carnitine, a trimethylamine abundant in red meat, also produces TMAO and accelerates atherosclerosis in mice. Omnivorous human subjects produced more TMAO than did vegans or vegetarians following ingestion of L-carnitine through a microbiota-dependent mechanism. The presence of specific bacterial taxa in human feces was associated with both plasma TMAO concentration and dietary status. Plasma L-carnitine levels in subjects undergoing cardiac evaluation (n = 2,595) predicted increased risks for both prevalent cardiovascular disease (CVD) and incident major adverse cardiac events (myocardial infarction, stroke or death), but only among subjects with concurrently high TMAO levels. Chronic dietary L-carnitine supplementation in mice altered cecal microbial composition, markedly enhanced synthesis of TMA and TMAO, and increased atherosclerosis, but this did not occur if intestinal microbiota was concurrently suppressed. In mice with an intact intestinal microbiota, dietary supplementation with TMAO or either carnitine or choline reduced in vivo reverse cholesterol transport. Intestinal microbiota may thus contribute to the well-established link between high levels of red meat consumption and CVD risk.
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Protein carbamylation predicts mortality in ESRD.
J. Am. Soc. Nephrol.
PUBLISHED: 02-21-2013
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Traditional risk factors fail to explain the increased risk for cardiovascular morbidity and mortality in ESRD. Cyanate, a reactive electrophilic species in equilibrium with urea, posttranslationally modifies proteins through a process called carbamylation, which promotes atherosclerosis. The plasma level of protein-bound homocitrulline (PBHCit), which results from carbamylation, predicts major adverse cardiac events in patients with normal renal function, but whether this relationship is similar in ESRD is unknown. We quantified serum PBHCit in a cohort of 347 patients undergoing maintenance hemodialysis with 5 years of follow-up. Kaplan-Meier analyses revealed a significant association between elevated PBHCit and death (log-rank P<0.01). After adjustment for patient characteristics, laboratory values, and comorbid conditions, the risk for death among patients with PBHCit values in the highest tertile was more than double the risk among patients with values in the middle tertile (adjusted hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.5-3.9) or the lowest tertile (adjusted HR, 2.3; 95% CI, 1.5-3.7). Including PBHCit significantly improved the multivariable model, with a net reclassification index of 14% (P<0.01). In summary, serum PBHCit, a footprint of protein carbamylation, predicts increased cardiovascular risk in patients with ESRD, supporting a mechanistic link among uremia, inflammation, and atherosclerosis.
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Nitric oxide bioavailability and adiponectin production in chronic systolic heart failure: relation to severity of cardiac dysfunction.
Transl Res
PUBLISHED: 02-12-2013
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Adiponectin is an anti-inflammatory, antiatherogenic adipokine elevated in heart failure (HF) that may protect against endothelial dysfunction by influencing underlying nitric oxide bioavailability. In this study, we examine the relationship between plasma adiponectin levels and measures of nitric oxide bioavailability and myocardial performance in patients with chronic systolic HF. In 139 ambulatory patients with stable, chronic systolic HF (left ventricular [LV] ejection fraction ?40%, New York Heart Association class I to IV), we measured plasma levels of adiponectin, asymmetric dimethylarginine (ADMA), and global arginine bioavailability (GABR), and performed comprehensive echocardiography with assessment of cardiac structure and performance. Adverse events (all-cause mortality or cardiac transplantation) were prospectively tracked for a median of 39 months. Plasma adiponectin levels directly correlated with plasma ADMA levels (Spearmans r = 0.41, P < 0.001) and aminoterminal pro-B-type natriuretic peptide (NT-proBNP) levels (r = 0.55, P < 0.001), inversely correlated with GABR (r = -0.39, P < 0.001), and were not associated with high-sensitivity C-reactive protein (P = 0.81) or myeloperoxidase (P = 0.07). Interestingly, increased plasma adiponectin levels remained positively correlated with plasma ADMA levels only in patients with elevated NT-proBNP levels (r = 0.33, P = 0.009). Higher plasma adiponectin levels were associated with worse LV diastolic dysfunction (rank sums P = 0.002), right ventricular (RV) systolic dysfunction (rank sums P = 0.002), and RV diastolic dysfunction (rank sums P = 0.011), but not after adjustment for plasma ADMA and NT-proBNP levels. Plasma adiponectin levels predicted increased risk of adverse clinical events (hazard ratio, 95% confidence interval 1.45 [1.02-2.07], P = 0.038) but not after adjustment for plasma ADMA and NT-proBNP levels, or echocardiographic indices of diastolic or RV systolic dysfunction. In patients with chronic systolic HF, adiponectin production is more closely linked with nitric oxide bioavailability than inflammation, and appears to be more robust in the setting of cardiac dysfunction or elevated natriuretic peptide levels.
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Detectable subclinical myocardial necrosis is associated with cardiovascular risk in stable patients with diabetes.
Diabetes Care
PUBLISHED: 02-07-2013
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To investigate the relationship between different degrees of subclinical myocardial necrosis, glycemic control, and long-term adverse clinical outcomes within a stable patient population with diabetes mellitus.
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Protein carbamylation in chronic systolic heart failure: relationship with renal impairment and adverse long-term outcomes.
J. Card. Fail.
PUBLISHED: 01-30-2013
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Protein carbamylation, a posttranslational modification promoted during uremia and catalyzed by myeloperoxidase (MPO) at sites of inflammation, is linked to altered protein structure, vascular dysfunction, and poor prognosis. We examine the relationship between plasma protein-bound homocitrulline (PBHCit) levels, a marker of protein lysine residue carbamylation, with cardiorenal function and long-term outcomes in chronic systolic heart failure (HF).
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The low-resolution structure of nHDL reconstituted with DMPC with and without cholesterol reveals a mechanism for particle expansion.
J. Lipid Res.
PUBLISHED: 01-23-2013
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Small-angle neutron scattering (SANS) with contrast variation was used to obtain the low-resolution structure of nascent HDL (nHDL) reconstituted with dimyristoyl phosphatidylcholine (DMPC) in the absence and presence of cholesterol, [apoA1:DMPC (1:80, mol:mol) and apoA1:DMPC:cholesterol (1:86:9, mol:mol:mol)]. The overall shape of both particles is discoidal with the low-resolution structure of apoA1 visualized as an open, contorted, and out of plane conformation with three arms in nascent HDL/dimyristoyl phosphatidylcholine without cholesterol (nHDL(DMPC)) and two arms in nascent HDL/dimyristoyl phosphatidylcholine with cholesterol (nHDL(DMPC+Chol)). The low-resolution shape of the lipid phase in both nHDL(DMPC) and nHDL(DMPC+Chol) were oblate ellipsoids, and fit well within their respective protein shapes. Modeling studies indicate that apoA1 is folded onto itself in nHDL(DMPC), making a large hairpin, which was also confirmed independently by both cross-linking mass spectrometry and hydrogen-deuterium exchange (HDX) mass spectrometry analyses. In nHDL(DMPC+Chol), the lipid was expanded and no hairpin was visible. Importantly, despite the overall discoidal shape of the whole particle in both nHDL(DMPC) and nHDL(DMPC+Chol), an open conformation (i.e., not a closed belt) of apoA1 is observed. Collectively, these data show that full length apoA1 retains an open architecture that is dictated by its lipid cargo. The lipid is likely predominantly organized as a bilayer with a micelle domain between the open apoA1 arms. The apoA1 configuration observed suggests a mechanism for accommodating changing lipid cargo by quantized expansion of hairpin structures.
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Trimethylamine-N-oxide, a metabolite associated with atherosclerosis, exhibits complex genetic and dietary regulation.
Cell Metab.
PUBLISHED: 01-15-2013
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Circulating trimethylamine-N-oxide (TMAO) levels are strongly associated with atherosclerosis. We now examine genetic, dietary, and hormonal factors regulating TMAO levels. We demonstrate that two flavin mono-oxygenase family members, FMO1 and FMO3, oxidize trimethylamine (TMA), derived from gut flora metabolism of choline, to TMAO. Further, we show that FMO3 exhibits 10-fold higher specific activity than FMO1. FMO3 overexpression in mice significantly increases plasma TMAO levels while silencing FMO3 decreases TMAO levels. In both humans and mice, hepatic FMO3 expression is reduced in males compared to females. In mice, this reduction in FMO3 expression is due primarily to downregulation by androgens. FMO3 expression is induced by dietary bile acids by a mechanism that involves the farnesoid X receptor (FXR), a bile acid-activated nuclear receptor. Analysis of natural genetic variation among inbred strains of mice indicates that FMO3 and TMAO are significantly correlated, and TMAO levels explain 11% of the variation in atherosclerosis.
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Treatment strategies in patients with statin intolerance: the Cleveland Clinic experience.
Am. Heart J.
PUBLISHED: 01-03-2013
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Statin therapy is a proven effective treatment of hyperlipidemia. However, a significant number of patients cannot tolerate statins. This study was conducted to review treatment strategies for patients intolerant to statin therapy with a focus on intermittent statin dosing.
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Diminished global arginine bioavailability as a metabolic defect in chronic systolic heart failure.
J. Card. Fail.
PUBLISHED: 01-02-2013
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Systemic alterations in arginine bioavailability occur in heart failure (HF) patients with more advanced myocardial dysfunction and poorer clinical outcomes, and they improve with beta-blocker therapy.
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Clinical and genetic association of serum ceruloplasmin with cardiovascular risk.
Arterioscler. Thromb. Vasc. Biol.
PUBLISHED: 11-10-2011
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Ceruloplasmin (Cp) is an acute-phase reactant that is increased in inflammatory diseases and in acute coronary syndromes. Cp has recently been shown to possess nitric oxide (NO) oxidase catalytic activity, but its impact on long-term cardiovascular outcomes in stable cardiac patients has not been explored.
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New gene functions in megakaryopoiesis and platelet formation.
Christian Gieger, Aparna Radhakrishnan, Ana Cvejic, Weihong Tang, Eleonora Porcu, Giorgio Pistis, Jovana Serbanovic-Canic, Ulrich Elling, Alison H Goodall, Yann Labrune, Lorna M Lopez, Reedik Mägi, Stuart Meacham, Yukinori Okada, Nicola Pirastu, Rossella Sorice, Alexander Teumer, Katrin Voss, Weihua Zhang, Ramiro Ramirez-Solis, Joshua C Bis, David Ellinghaus, Martin Gögele, Jouke-Jan Hottenga, Claudia Langenberg, Peter Kovacs, Paul F O'Reilly, So-Youn Shin, Tonu Esko, Jaana Hartiala, Stavroula Kanoni, Federico Murgia, Afshin Parsa, Jonathan Stephens, Pim van der Harst, C Ellen van der Schoot, Hooman Allayee, Antony Attwood, Beverley Balkau, François Bastardot, Saonli Basu, Sebastian E Baumeister, Ginevra Biino, Lorenzo Bomba, Amélie Bonnefond, Francois Cambien, John C Chambers, Francesco Cucca, Pio D'Adamo, Gail Davies, Rudolf A de Boer, Eco J C de Geus, Angela Döring, Paul Elliott, Jeanette Erdmann, David M Evans, Mario Falchi, Wei Feng, Aaron R Folsom, Ian H Frazer, Quince D Gibson, Nicole L Glazer, Chris Hammond, Anna-Liisa Hartikainen, Susan R Heckbert, Christian Hengstenberg, Micha Hersch, Thomas Illig, Ruth J F Loos, Jennifer Jolley, Kay Tee Khaw, Brigitte Kühnel, Marie-Christine Kyrtsonis, Vasiliki Lagou, Heather Lloyd-Jones, Thomas Lumley, Massimo Mangino, Andrea Maschio, Irene Mateo Leach, Barbara McKnight, Yasin Memari, Braxton D Mitchell, Grant W Montgomery, Yusuke Nakamura, Matthias Nauck, Gerjan Navis, Ute Nöthlings, Ilja M Nolte, David J Porteous, Anneli Pouta, Peter P Pramstaller, Janne Pullat, Susan M Ring, Jerome I Rotter, Daniela Ruggiero, Aimo Ruokonen, Cinzia Sala, Nilesh J Samani, Jennifer Sambrook, David Schlessinger, Stefan Schreiber, Heribert Schunkert, James Scott, Nicholas L Smith, Harold Snieder, John M Starr, Michael Stumvoll, Atsushi Takahashi, W H Wilson Tang, Kent Taylor, Albert Tenesa, Swee Lay Thein, Anke Tönjes, Manuela Uda, Sheila Ulivi, Dirk J van Veldhuisen, Peter M Visscher, Uwe Völker, H-Erich Wichmann, Kerri L Wiggins, Gonneke Willemsen, Tsun-Po Yang, Jing Hua Zhao, Paavo Zitting, John R Bradley, George V Dedoussis, Paolo Gasparini, Stanley L Hazen, Andres Metspalu, Mario Pirastu, Alan R Shuldiner, L Joost van Pelt, Jaap-Jan Zwaginga, Dorret I Boomsma, Ian J Deary, Andre Franke, Philippe Froguel, Santhi K Ganesh, Marjo-Riitta Järvelin, Nicholas G Martin, Christa Meisinger, Bruce M Psaty, Timothy D Spector, Nicholas J Wareham, Jan-Willem N Akkerman, Marina Ciullo, Panos Deloukas, Andreas Greinacher, Steve Jupe, Naoyuki Kamatani, Jyoti Khadake, Jaspal S Kooner, Josef Penninger, Inga Prokopenko, Derek Stemple, Daniela Toniolo, Lorenz Wernisch, Serena Sanna, Andrew A Hicks, Augusto Rendon, Manuel A Ferreira, Willem H Ouwehand, Nicole Soranzo.
Nature
PUBLISHED: 10-21-2011
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Platelets are the second most abundant cell type in blood and are essential for maintaining haemostasis. Their count and volume are tightly controlled within narrow physiological ranges, but there is only limited understanding of the molecular processes controlling both traits. Here we carried out a high-powered meta-analysis of genome-wide association studies (GWAS) in up to 66,867 individuals of European ancestry, followed by extensive biological and functional assessment. We identified 68 genomic loci reliably associated with platelet count and volume mapping to established and putative novel regulators of megakaryopoiesis and platelet formation. These genes show megakaryocyte-specific gene expression patterns and extensive network connectivity. Using gene silencing in Danio rerio and Drosophila melanogaster, we identified 11 of the genes as novel regulators of blood cell formation. Taken together, our findings advance understanding of novel gene functions controlling fate-determining events during megakaryopoiesis and platelet formation, providing a new example of successful translation of GWAS to function.
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Eight genetic loci associated with variation in lipoprotein-associated phospholipase A2 mass and activity and coronary heart disease: meta-analysis of genome-wide association studies from five community-based studies.
Eur. Heart J.
PUBLISHED: 10-14-2011
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Lipoprotein-associated phospholipase A2 (Lp-PLA2) generates proinflammatory and proatherogenic compounds in the arterial vascular wall and is a potential therapeutic target in coronary heart disease (CHD). We searched for genetic loci related to Lp-PLA2 mass or activity by a genome-wide association study as part of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium.
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Investigation of 95 variants identified in a genome-wide study for association with mortality after acute coronary syndrome.
BMC Med. Genet.
PUBLISHED: 09-29-2011
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Genome-wide association studies (GWAS) have identified new candidate genes for the occurrence of acute coronary syndrome (ACS), but possible effects of such genes on survival following ACS have yet to be investigated.
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Risk prediction with serial myeloperoxidase monitoring in patients with acute chest pain.
Clin. Chem.
PUBLISHED: 09-22-2011
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Although myeloperoxidase (MPO) monitoring is predictive for cardiovascular outcomes in suspected acute coronary syndromes, the value of serial testing is unknown.
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Reduced cardiovascular risk following bariatric surgeries is related to a partial recovery from "adiposopathy".
Obes Surg
PUBLISHED: 06-01-2011
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Altered cytokine secretion from dysfunctional adipose tissue or "adiposopathy" is implicated in obesity related inflammation and may mediate reduced cardiovascular disease (CVD) risk in response to weight loss after bariatric surgery. We hypothesized that bariatric surgery reduces CVD risk by favorably altering the pro-inflammatory profile of adipose tissue as a result of weight loss.
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Heparin-associated anti-Xa activity and platelet-derived prothrombotic and proinflammatory biomarkers in moderate to high-risk patients with acute coronary syndrome.
J. Thromb. Thrombolysis
PUBLISHED: 04-26-2011
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Heparin compounds, to include fractionated and unfractionated preparations, exert both antithrombotic and antiinflammatory effects through combined inhibition of factor Xa and thrombin. The contribution of modulated platelet activity in vivo is less clearly defined. The SYNERGY library was a prospectively designed repository for candidate clinical, hemostatic, platelet, and molecular biomarkers from patients participating in SYNERGY--a large-scale, randomized clinical trial evaluating the comparative benefits of unfractionated heparin (UFH) and enoxaparin in high-risk patients with acute coronary syndrome (ACS). Samples were collected from 201 patients enrolled at 26 experienced, participating sites and shipped to established core laboratories for analysis of platelet, endothelium-derived, inflammatory and coagulation activity biomarkers. Tissue factor pathway inhibitor (TFPI)--a vascular endothelial cell-derived factor Xa regulatory protein-correlated directly with plasma anti-Xa activity (unadjusted: r = 0.23, P < 0.0001; adjusted: ? = 0.10; P = 0.001), as did TFPI-fXa complexes (unadjusted: r = 0.34, P < 0.0001; adjusted: ? = 0.38; P = < 0.0001). In contrast, there was a direct and inverse relationship between anti-Xa activity and two platelet-derived biomarkers-plasminogen activator inhibitor-1 (unadjusted: r = -0.18, P = 0.0012; adjusted: ? = -0.10; P = 0.021) and soluble CD40 ligand (unadjusted: r = -0.11, P = 0.05; adjusted: ? = -0.13; P = 0.049). All measured analyte relationships persisted after adjustment for age, creatinine clearance, weight, sex, and duration of treatment. Differences in biomarkers between patients receiving UFH and those randomized to enoxaparin were not observed. The ability of heparin compounds to affect the prothrombotic and proinflammatory states which characterize ACS may involve factor Xa-related modulation of platelet activation and expression. Whether this potentially beneficial effect is direct or indirect and achieved, at least in part, through the release of endothelial cell-derived coagulation regulatory proteins will require further investigation.
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Large-scale association analysis identifies 13 new susceptibility loci for coronary artery disease.
Heribert Schunkert, Inke R König, Sekar Kathiresan, Muredach P Reilly, Themistocles L Assimes, Hilma Holm, Michael Preuss, Alexandre F R Stewart, Maja Barbalic, Christian Gieger, Devin Absher, Zouhair Aherrahrou, Hooman Allayee, David Altshuler, Sonia S Anand, Karl Andersen, Jeffrey L Anderson, Diego Ardissino, Stephen G Ball, Anthony J Balmforth, Timothy A Barnes, Diane M Becker, Lewis C Becker, Klaus Berger, Joshua C Bis, S Matthijs Boekholdt, Eric Boerwinkle, Peter S Braund, Morris J Brown, Mary Susan Burnett, Ian Buysschaert, , John F Carlquist, Li Chen, Sven Cichon, Veryan Codd, Robert W Davies, George Dedoussis, Abbas Dehghan, Serkalem Demissie, Joseph M Devaney, Patrick Diemert, Ron Do, Angela Doering, Sandra Eifert, Nour Eddine El Mokhtari, Stephen G Ellis, Roberto Elosua, James C Engert, Stephen E Epstein, Ulf de Faire, Marcus Fischer, Aaron R Folsom, Jennifer Freyer, Bruna Gigante, Domenico Girelli, Solveig Gretarsdottir, Vilmundur Gudnason, Jeffrey R Gulcher, Eran Halperin, Naomi Hammond, Stanley L Hazen, Albert Hofman, Benjamin D Horne, Thomas Illig, Carlos Iribarren, Gregory T Jones, J Wouter Jukema, Michael A Kaiser, Lee M Kaplan, John J P Kastelein, Kay-Tee Khaw, Joshua W Knowles, Genovefa Kolovou, Augustine Kong, Reijo Laaksonen, Diether Lambrechts, Karin Leander, Guillaume Lettre, Mingyao Li, Wolfgang Lieb, Christina Loley, Andrew J Lotery, Pier M Mannucci, Seraya Maouche, Nicola Martinelli, Pascal P McKeown, Christa Meisinger, Thomas Meitinger, Olle Melander, Pier Angelica Merlini, Vincent Mooser, Thomas Morgan, Thomas W Mühleisen, Joseph B Muhlestein, Thomas Münzel, Kiran Musunuru, Janja Nahrstaedt, Christopher P Nelson, Markus M Nöthen, Oliviero Olivieri, Riyaz S Patel, Chris C Patterson, Annette Peters, Flora Peyvandi, Liming Qu, Arshed A Quyyumi, Daniel J Rader, Loukianos S Rallidis, Catherine Rice, Frits R Rosendaal, Diana Rubin, Veikko Salomaa, M Lourdes Sampietro, Manj S Sandhu, Eric Schadt, Arne Schäfer, Arne Schillert, Stefan Schreiber, Jürgen Schrezenmeir, Stephen M Schwartz, David S Siscovick, Mohan Sivananthan, Suthesh Sivapalaratnam, Albert Smith, Tamara B Smith, Jaapjan D Snoep, Nicole Soranzo, John A Spertus, Klaus Stark, Kathy Stirrups, Monika Stoll, W H Wilson Tang, Stephanie Tennstedt, Gudmundur Thorgeirsson, Gudmar Thorleifsson, Maciej Tomaszewski, André G Uitterlinden, Andre M van Rij, Benjamin F Voight, Nick J Wareham, George A Wells, H-Erich Wichmann, Philipp S Wild, Christina Willenborg, Jaqueline C M Witteman, Benjamin J Wright, Shu Ye, Tanja Zeller, Andreas Ziegler, Francois Cambien, Alison H Goodall, L Adrienne Cupples, Thomas Quertermous, Winfried März, Christian Hengstenberg, Stefan Blankenberg, Willem H Ouwehand, Alistair S Hall, Panos Deloukas, John R Thompson, Kari Stefansson, Robert Roberts, Unnur Thorsteinsdottir, Christopher J O'Donnell, Ruth McPherson, Jeanette Erdmann, Nilesh J Samani.
Nat. Genet.
PUBLISHED: 02-10-2011
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We performed a meta-analysis of 14 genome-wide association studies of coronary artery disease (CAD) comprising 22,233 individuals with CAD (cases) and 64,762 controls of European descent followed by genotyping of top association signals in 56,682 additional individuals. This analysis identified 13 loci newly associated with CAD at P < 5 × 10?? and confirmed the association of 10 of 12 previously reported CAD loci. The 13 new loci showed risk allele frequencies ranging from 0.13 to 0.91 and were associated with a 6% to 17% increase in the risk of CAD per allele. Notably, only three of the new loci showed significant association with traditional CAD risk factors and the majority lie in gene regions not previously implicated in the pathogenesis of CAD. Finally, five of the new CAD risk loci appear to have pleiotropic effects, showing strong association with various other human diseases or traits.
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Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease.
Nature
PUBLISHED: 02-09-2011
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Metabolomics studies hold promise for the discovery of pathways linked to disease processes. Cardiovascular disease (CVD) represents the leading cause of death and morbidity worldwide. Here we used a metabolomics approach to generate unbiased small-molecule metabolic profiles in plasma that predict risk for CVD. Three metabolites of the dietary lipid phosphatidylcholine--choline, trimethylamine N-oxide (TMAO) and betaine--were identified and then shown to predict risk for CVD in an independent large clinical cohort. Dietary supplementation of mice with choline, TMAO or betaine promoted upregulation of multiple macrophage scavenger receptors linked to atherosclerosis, and supplementation with choline or TMAO promoted atherosclerosis. Studies using germ-free mice confirmed a critical role for dietary choline and gut flora in TMAO production, augmented macrophage cholesterol accumulation and foam cell formation. Suppression of intestinal microflora in atherosclerosis-prone mice inhibited dietary-choline-enhanced atherosclerosis. Genetic variations controlling expression of flavin monooxygenases, an enzymatic source of TMAO, segregated with atherosclerosis in hyperlipidaemic mice. Discovery of a relationship between gut-flora-dependent metabolism of dietary phosphatidylcholine and CVD pathogenesis provides opportunities for the development of new diagnostic tests and therapeutic approaches for atherosclerotic heart disease.
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The low resolution structure of ApoA1 in spherical high density lipoprotein revealed by small angle neutron scattering.
J. Biol. Chem.
PUBLISHED: 02-03-2011
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Spherical high density lipoprotein (sHDL), a key player in reverse cholesterol transport and the most abundant form of HDL, is associated with cardiovascular diseases. Small angle neutron scattering with contrast variation was used to determine the solution structure of protein and lipid components of reconstituted sHDL. Apolipoprotein A1, the major protein of sHDL, forms a hollow structure that cradles a central compact lipid core. Three apoA1 chains are arranged within the low resolution structure of the protein component as one of three possible global architectures: (i) a helical dimer with a hairpin (HdHp), (ii) three hairpins (3Hp), or (iii) an integrated trimer (iT) in which the three apoA1 monomers mutually associate over a portion of the sHDL surface. Cross-linking and mass spectrometry analyses help to discriminate among the three molecular models and are most consistent with the HdHp overall architecture of apoA1 within sHDL.
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Genetic contribution of the leukotriene pathway to coronary artery disease.
Hum. Genet.
PUBLISHED: 01-27-2011
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We evaluated the genetic contribution of the leukotriene (LT) pathway to risk of coronary artery disease (CAD) in 4,512 Caucasian and African American subjects ascertained through elective cardiac evaluation. Of the three previously associated variants, the shorter "3" and "4" alleles of a promoter repeat polymorphism in ALOX5 increased risk of CAD in African Americans (OR = 1.4, 95% CI 1.0-1.9; p = 0.04), whereas a haplotype of LTA4H (HapK) was associated with CAD in Caucasians (OR = 1.2, 95% CI 1.01-1.4; p = 0.03). In Caucasians, first-stage analysis of 254 haplotype-tagging SNPs in 15 LT pathway genes with follow-up of 19 variants in stage 2 revealed an LTA4H SNP (rs2540477) that increased risk of CAD (OR = 1.2, 95% CI 1.1-1.5; p = 0.003) and a PLA2G4A SNP (rs12746200) that decreased risk of CAD (OR = 0.7, 95% CI 0.6-0.9; p = 0.0007). The PLA2G4A rs12746200 variant also decreased risk of experiencing a major adverse cardiac event (MACE = myocardial infarction, stroke, or death) over 3 years of follow-up (HR = 0.7, 95% CI 0.5-0.9; p = 0.01), consistent with its cardioprotective effect. Functional experiments demonstrated that stimulated monocytes from carriers of LTA4H variants HapK or rs2540477 had 50% (p = 0.002) and 33% (p = 0.03) higher LTB(4) production, respectively, compared to non-carriers. These ex vivo results are consistent with LTB(4) being the direct product of the reaction catalyzed by LTA4H and its role in promoting monocyte chemotaxis to sites of inflammation, including the artery wall of atherosclerotic lesions. Taken together, this study provides additional evidence that functional genetic variation of the LT pathway can mediate atherogenic processes and the risk of CAD in humans.
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Urinary bromotyrosine measures asthma control and predicts asthma exacerbations in children.
J. Pediatr.
PUBLISHED: 01-18-2011
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To determine the usefulness of urinary bromotyrosine, a noninvasive marker of eosinophil-catalyzed protein oxidation, in tracking with indexes of asthma control and in predicting future asthma exacerbations in children.
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Genome-wide association study of coronary heart disease and its risk factors in 8,090 African Americans: the NHLBI CARe Project.
PLoS Genet.
PUBLISHED: 01-07-2011
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Coronary heart disease (CHD) is the leading cause of mortality in African Americans. To identify common genetic polymorphisms associated with CHD and its risk factors (LDL- and HDL-cholesterol (LDL-C and HDL-C), hypertension, smoking, and type-2 diabetes) in individuals of African ancestry, we performed a genome-wide association study (GWAS) in 8,090 African Americans from five population-based cohorts. We replicated 17 loci previously associated with CHD or its risk factors in Caucasians. For five of these regions (CHD: CDKN2A/CDKN2B; HDL-C: FADS1-3, PLTP, LPL, and ABCA1), we could leverage the distinct linkage disequilibrium (LD) patterns in African Americans to identify DNA polymorphisms more strongly associated with the phenotypes than the previously reported index SNPs found in Caucasian populations. We also developed a new approach for association testing in admixed populations that uses allelic and local ancestry variation. Using this method, we discovered several loci that would have been missed using the basic allelic and global ancestry information only. Our conclusions suggest that no major loci uniquely explain the high prevalence of CHD in African Americans. Our project has developed resources and methods that address both admixture- and SNP-association to maximize power for genetic discovery in even larger African-American consortia.
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Diminished antioxidant activity of high-density lipoprotein-associated proteins in systolic heart failure.
Circ Heart Fail
PUBLISHED: 11-09-2010
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Diminished serum arylesterase activity, catalyzed by the high-density lipoprotein-associated paraoxonase-1, is associated with heightened systemic oxidative stress and atherosclerosis risk. In the present study, we sought to determine the prognostic role of serum arylesterase activity in subjects with systolic heart failure, particularly in relation to established cardiac biomarkers.
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Plasma myeloperoxidase predicts incident cardiovascular risks in stable patients undergoing medical management for coronary artery disease.
Clin. Chem.
PUBLISHED: 11-08-2010
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Myeloperoxidase (MPO) concentrations predict adverse clinical outcomes in the setting of acute coronary syndromes and heart failure, but the prognostic role of MPO in stable patients with known atherosclerotic burden is unclear.
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Improved prediction of cardiovascular disease based on a panel of single nucleotide polymorphisms identified through genome-wide association studies.
Circ Cardiovasc Genet
PUBLISHED: 08-21-2010
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Genome-wide association studies (GWAS) have identified single-nucleotide polymorphisms (SNPs) at multiple loci that are significantly associated with coronary artery disease (CAD) risk. In this study, we sought to determine and compare the predictive capabilities of 9p21.3 alone and a panel of SNPs identified and replicated through GWAS for CAD.
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Congruency between biophysical data from multiple platforms and molecular dynamics simulation of the double-super helix model of nascent high-density lipoprotein.
Biochemistry
PUBLISHED: 08-07-2010
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The predicted structure and molecular trajectories from >80 ns molecular dynamics simulation of the solvated Double-Super Helix (DSH) model of nascent high-density lipoprotein (HDL) were determined and compared with experimental data on reconstituted nascent HDL obtained from multiple biophysical platforms, including small angle neutron scattering (SANS) with contrast variation, hydrogen-deuterium exchange tandem mass spectrometry (H/D-MS/MS), nuclear magnetic resonance spectroscopy (NMR), cross-linking tandem mass spectrometry (MS/MS), fluorescence resonance energy transfer (FRET), electron spin resonance spectroscopy (ESR), and electron microscopy. In general, biophysical constraints experimentally derived from the multiple platforms agree with the same quantities evaluated using the simulation trajectory. Notably, key structural features postulated for the recent DSH model of nascent HDL are retained during the simulation, including (1) the superhelical conformation of the antiparallel apolipoprotein A1 (apoA1) chains, (2) the lipid micellar-pseudolamellar organization, and (3) the solvent-exposed Solar Flare loops, proposed sites of interaction with LCAT (lecithin cholesteryl acyltransferase). Analysis of salt bridge persistence during simulation provides insights into structural features of apoA1 that forms the backbone of the lipoprotein. The combination of molecular dynamics simulation and experimental data from a broad range of biophysical platforms serves as a powerful approach to studying large macromolecular assemblies such as lipoproteins. This application to nascent HDL validates the DSH model proposed earlier and suggests new structural details of nascent HDL.
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A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells.
J. Lipid Res.
PUBLISHED: 08-04-2010
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A precise and sensitive method for measuring cellular free and esterified cholesterol is required in order to perform studies of macrophage cholesterol loading, metabolism, storage, and efflux. Until now, the use of an enzymatic cholesterol assay, commonly used for aqueous phase plasma cholesterol assays, has not been optimized for use with solid phase samples such as cells, due to inefficient solubilization of total cholesterol in enzyme compatible solvents. We present an efficient solubilization protocol compatible with an enzymatic cholesterol assay that does not require chemical saponification or chromatographic separation. Another issue with enzyme compatible solvents is the presence of endogenous peroxides that interfere with the enzymatic cholesterol assay. We overcame this obstacle by pretreatment of the reaction solution with the enzyme catalase, which consumed endogenous peroxides resulting in reduced background and increased sensitivity in our method. Finally, we demonstrated that this method for cholesterol quantification in macrophages yields results that are comparable to those measured by stable isotope dilution gas chromatography with mass spectrometry detection. In conclusion, we describe a sensitive, simple, and high-throughput enzymatic method to quantify cholesterol in complex matrices such as cells.
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Mass spectrometric profiling of oxidized lipid products in human nonalcoholic fatty liver disease and nonalcoholic steatohepatitis.
J. Lipid Res.
PUBLISHED: 07-14-2010
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Oxidative stress is a core abnormality responsible for disease progression in nonalcoholic fatty liver disease (NAFLD). However, the pathways that contribute to oxidative damage in vivo are poorly understood. Our aims were to define the circulating profile of lipid oxidation products in NAFLD patients, the source of these products, and assess whether their circulating levels reflect histological changes in the liver. The levels of multiple structurally specific oxidized fatty acids, including individual hydroxy-eicosatetraenoic acids (HETE), hydroxy-octadecadenoic acids (HODE), and oxo-octadecadenoic acids (oxoODE), were measured by mass spectrometry in plasma at time of liver biopsy in an initial cohort of 73 and a validation cohort of 49 consecutive patients. Of the markers monitored, 9- and 13-HODEs and 9- and 13-oxoODEs, products of free radical-mediated oxidation of linoleic acid (LA), were significantly elevated in patients with nonalcoholic steatohepatitis (NASH), compared with patients with steatosis. A strong correlation was revealed between these oxidation products and liver histopathology (inflammation, fibrosis, and steatosis). Further analyses of HODEs showed equivalent R and S chiral distribution. A risk score for NASH (oxNASH) was developed in the initial clinical cohort and shown to have high diagnostic accuracy for NASH versus steatosis in the independent validation cohort. Subjects with elevated oxNASH levels (top tertile) were 9.7-fold (P < 0.0001) more likely to have NASH than those with low levels (bottom tertile). Collectively, these findings support a key role for free radical-mediated linoleic acid oxidation in human NASH and define a risk score, oxNASH, for noninvasive detection of the presence of NASH.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.