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  • American Heart Association (AHA)  (46)
  • The American Physiological Society (APS)  (38)
  • American Association for the Advancement of Science (AAAS)  (35)
Document type
Years
  • 1
    Publication Date: 2013-06-19
    Description: Background— Two endophenotypes of arterial calcification, calcification on arterial wall and calcification in atherosclerotic plaques, are associated with different types of cardiovascular events. Mgp -deficient mice showed matrix Gla protein (MGP) is strongly associated with calcification on arterial wall without atherosclerotic plaques, and MGP variants were not significantly associated with myocardial infarction. MGP may play different roles in the 2 endophenotypes. Methods and Results— We analyzed the associations of MGP variants rs4236, rs1800801, and rs1800802 with the 2 endophenotypes determined by multidetector computed tomography angiography. A total of 585 with calcification on coronary artery wall, 675 with calcification in coronary atherosclerotic plaques, 454 with calcification on aortic wall, and 725 controls were enrolled. After Bonferroni correction, rs4236 and rs1800801 were still associated with calcification on arterial wall, the odds ratios were 0.708 (95% confidence interval, 0.540–0.928) for rs4236 and 0.652 (95% confidence interval, 0.479–0.888) for rs1800801 in coronary artery wall calcification, and 0.699 (95% confidence interval, 0.525–0.931) for rs4236 and 0.650 (95% confidence interval, 0.467–0.905) for rs1800801 in aortic wall calcification, respectively. The variants were correlated with calcification severity by ln(CAC Agatston score+1) in coronary artery wall calcification but not in atherosclerotic plaque calcification. In accordance with their associations with calcification on arterial wall, rs4236C and rs1800801A were associated with higher MGP plasma levels, whereas rs1800802C was associated with lower MGP levels in normal controls. Because of the role of calcification in plaque vulnerability, their associations with acute myocardial infarction were also determined in 771 controls and 752 patients, no association was found. Conclusions— MGP genetic variants showed association with calcification on arterial wall but not with calcification in atherosclerotic plaques.
    Keywords: Clinical genetics, Risk Factors, Acute myocardial infarction, Other Vascular biology
    Print ISSN: 1942-325X
    Electronic ISSN: 1942-3268
    Topics: Medicine
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  • 2
    Publication Date: 2016-02-21
    Description: Anderson (disorder-induced) localization, proposed more than half a century ago, has inspired numerous efforts to explore the absence of wave diffusions in disordered media. However, the proposed disorder-induced metal-insulator transition (MIT), associated with the nonpropagative electron waves, has hardly been observed in three-dimensional (3D) crystalline materials, let alone single crystals. We report the observation of an MIT in centimeter-size single crystals of Li x Fe 7 Se 8 induced by lattice disorder. Both specific heat and infrared reflectance measurements reveal the presence of considerable electronic states in the vicinity of the Fermi level when the MIT occurs, suggesting that the transition is not due to Coulomb repulsion mechanism. The 3D variable range hopping regime evidenced by electrical transport measurements at low temperatures indicates the localized nature of the electronic states on the Fermi level. Quantitative analyses of carrier concentration, carrier mobility, and simulated density of states (DOS) fully support that Li x Fe 7 Se 8 is an Anderson insulator. On the basis of these results, we provide a unified DOS picture to explain all the experimental results, and a schematic diagram for finding other potential Anderson insulators. This material will thus serve as a rich playground for both theoretical and experimental investigations on MITs and disorder-induced phenomena.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 3
    Publication Date: 2018-09-07
    Description: Plant immunity often penalizes growth and yield. The transcription factor Ideal Plant Architecture 1 (IPA1) reduces unproductive tillers and increases grains per panicle, which results in improved rice yield. Here we report that higher IPA1 levels enhance immunity. Mechanistically, phosphorylation of IPA1 at amino acid Ser 163 within its DNA binding domain occurs in response to infection by the fungus Magnaporthe oryzae and alters the DNA binding specificity of IPA1. Phosphorylated IPA1 binds to the promoter of the pathogen defense gene WRKY45 and activates its expression, leading to enhanced disease resistance. IPA1 returns to a nonphosphorylated state within 48 hours after infection, resuming support of the growth needed for high yield. Thus, IPA1 promotes both yield and disease resistance by sustaining a balance between growth and immunity.
    Keywords: Botany
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2012-08-16
    Description: A multitude of evidence suggests that iodinated contrast material causes nephrotoxicity; however, there have been no previous studies that use arterial spin labeling (ASL) blood flow functional magnetic resonance imaging (fMRI) to investigate the alterations in effective renal plasma flow between normointensive and hypertensive rats following injection of contrast media. We hypothesized that FAIR-SSFSE arterial spin labeling MRI may enable noninvasive and quantitative assessment of regional renal blood flow abnormalities and correlate with disease severity as assessed by histological methods. Renal blood flow (RBF) values of the cortex and medulla of rat kidneys were obtained from ASL images postprocessed at ADW4.3 workstation 0.3, 24, 48, and 72 h before and after injection of iodinated contrast media (6 ml/kg). The H&E method for morphometric measurements was used to confirm the MRI findings. The RBF values of the outer medulla were lower than those of the cortex and the inner medulla as reported previously. Iodinated contrast media treatment resulted in decreases in RBF in the outer medulla and cortex in spontaneously hypertensive rats (SHR), but only in the outer medulla in normotensive rats. The iodinated contrast agent significantly decreased the RBF value in the outer medulla and the cortex in SHR compared with normotensive rats after injection of the iodinated contrast media. Histological observations of kidney morphology were also consistent with ASL perfusion changes. These results demonstrate that the RBF value can reflect changes of renal perfusion in the cortex and medulla. ASL-MRI is a feasible and accurate method for evaluating nephrotoxic drugs-induced kidney damage.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
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  • 5
    Publication Date: 2012-07-16
    Description: Reflux of acid and bile acids contributes to epithelial tissue injury in gastro-esophageal reflux disease. However, the influence of refluxed material on human esophageal stratified epithelial barrier function and tight junction (TJ) proteins has not been fully elucidated. Here, we investigated the influence of acid and bile acids on barrier function and TJ protein distribution using a newly developed air-liquid interface (ALI) in vitro culture model of stratified squamous epithelium based on primary human esophageal epithelial cells (HEECs). Under ALI conditions, HEECs formed distinct epithelial layers on Transwell inserts after 7 days of culture. The epithelial layers formed TJ, and the presence of claudin-1, claudin-4, and occludin were detected by immunofluorescent staining. The NP-40-insoluble fraction of these TJ proteins was significantly higher by day 7 of ALI culture. Exposure of HEECs to pH 2, and taurocholic acid (TCA) and glycocholic acid (GCA) at pH 3, but not pH 4, for 1 h decreased transepithelial electrical resistance (TEER) and increased paracellular permeability. Exposure of cell layers to GCA (pH 3) and TCA (pH 3) for 1 h also markedly reduced the insoluble fractions of claudin-1 and -4. We found that deoxycholic acid (pH 7.4 or 6, 1 h) and pepsin (pH 3, 24 h) significantly decreased TEER and increased permeability. Based on these findings, ALI-cultured HEECs represent a new in vitro model of human esophageal stratified epithelium and are suitable for studying esophageal epithelial barrier functions. Using this model, we demonstrated that acid, bile acids, and pepsin disrupt squamous epithelial barrier function partly by modulating TJ proteins. These results provide new insights into understanding the role of TJ proteins in esophagitis.
    Print ISSN: 0193-1857
    Electronic ISSN: 1522-1547
    Topics: Medicine
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  • 6
    Publication Date: 2013-07-23
    Description: Background and Purpose— A novel quantitative susceptibility mapping (QSM) processing technology has been developed to map tissue susceptibility property without blooming artifacts. We hypothesize that hematoma volume measurement on QSM is independent of imaging parameters, eliminating its echo time dependence on gradient echo MRI. Methods— Gradient echo MRI of 16 patients with intracerebral hemorrhage was processed with susceptibility-weighted imaging, R 2 * (=1/T2*) mapping, and QSM at various echo times. Hematoma volumes were measured from these images. Results— Linear regression of hematoma volume versus echo time showed substantial slopes for gradient echo magnitude (0.45±0.31 L/s), susceptibility-weighted imaging (0.52±0.46), and R 2 * (0.39±0.30) but nearly zero slope for QSM (0.01±0.05). At echo time=20 ms, hematoma volume on QSM was 0.80 x that on gradient echo magnitude image ( R 2 =0.99). Conclusions— QSM can provide reliable measurement of hematoma volume, which can be performed rapidly and accurately using a semiautomated segmentation tool.
    Keywords: CT and MRI, Intracerebral Hemorrhage, Aneurysm, AVM, hematoma
    Print ISSN: 0039-2499
    Electronic ISSN: 1524-4628
    Topics: Medicine
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  • 7
    Publication Date: 2013-07-02
    Description: The barrier function of the esophageal epithelium is a major defense against gastroesophageal reflux disease. Previous studies have shown that reflux damage is reflected in a decrease in transepithelial electrical resistance associated with tight junction alterations in the esophageal epithelium. To develop novel therapies, it is critical to understand the molecular mechanisms whereby contact with a refluxate impairs esophageal barrier function. In this study, surgical models of duodenal and mixed reflux were developed in mice. Mouse esophageal epithelium was analyzed by gene microarray. Gene set enrichment analysis showed upregulation of inflammation-related gene sets and the NF-B pathway due to reflux. Significance analysis of microarrays revealed upregulation of NF-B target genes. Overexpression of NF-B subunits (p50 and p65) and NF-B target genes (matrix metalloproteinases-3 and -9, IL-1β, IL-6, and IL-8) confirmed activation of the NF-B pathway in the esophageal epithelium. In addition, real-time PCR, Western blotting, and immunohistochemical staining also showed downregulation and mislocalization of claudins-1 and -4. In a second animal experiment, treatment with an NF-B inhibitor, BAY 11-7085 (20 mg·kg –1 ·day –1 ip for 10 days), counteracted the effects of duodenal and mixed reflux on epithelial resistance and NF-B-regulated cytokines. We conclude that gastroesophageal reflux activates the NF-B pathway and impairs esophageal barrier function in mice and that targeting the NF-B pathway may strengthen esophageal barrier function against reflux.
    Print ISSN: 0193-1857
    Electronic ISSN: 1522-1547
    Topics: Medicine
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  • 8
    Publication Date: 2013-07-02
    Description: Mutations in cardiac myosin binding protein C (MyBP-C) are a common cause of familial hypertrophic cardiomyopathy (FHC). The majority of MyBP-C mutations are expected to reduce MyBP-C expression; however, the consequences of MyBP-C deficiency on the regulation of myofilament function, Ca 2+ homeostasis, and in vivo cardiac function are unknown. To elucidate the effects of decreased MyBP-C expression on cardiac function, we employed MyBP-C heterozygous null (MyBP-C +/– ) mice presenting decreases in MyBP-C expression (32%) similar to those of FHC patients carrying MyBP-C mutations. The levels of MyBP-C phosphorylation were reduced 53% in MyBP-C +/– hearts compared with wild-type hearts. Skinned myocardium isolated from MyBP-C +/– hearts displayed decreased cross-bridge stiffness at half-maximal Ca 2+ activations, increased steady-state force generation, and accelerated rates of cross-bridge recruitment at low Ca 2+ activations (〈15% and 〈25% of maximum, respectively). Protein kinase A treatment abolished basal differences in rates of cross-bridge recruitment between MyBP-C +/– and wild-type myocardium. Intact ventricular myocytes from MyBP-C +/– hearts displayed abnormal sarcomere shortening but unchanged Ca 2+ transient kinetics. Despite a lack of left ventricular hypertrophy, MyBP-C +/– hearts exhibited elevated end-diastolic pressure and decreased peak rate of LV pressure rise, which was normalized following dobutamine infusion. Furthermore, electrocardiogram recordings in conscious MyBP-C +/– mice revealed prolonged QRS and QT intervals, which are known risk factors for cardiac arrhythmia. Collectively, our data show that reduced MyBP-C expression and phosphorylation in the sarcomere result in myofilament dysfunction, contributing to contractile dysfunction that precedes compensatory adaptations in Ca 2+ handling, and chamber remodeling. Perturbations in mechanical and electrical activity in MyBP-C +/– mice could increase their susceptibility to cardiac dysfunction and arrhythmia.
    Print ISSN: 0363-6135
    Electronic ISSN: 1522-1539
    Topics: Medicine
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  • 9
    Publication Date: 2013-05-16
    Description: MicroRNAs (miRNAs) comprise of a novel class of endogenous small noncoding RNAs that frequently downregulate the expression of target genes. Recent reports suggest that miRNA-200b prevents epithelial-to-mesenchymal transition (EMT) in cancer cells by targeting the E-box binding transcription factors Zinc finger E-box-binding homeobox 1 (ZEB1) and Zinc finger E-box-binding homeobox 2 (ZEB2). About 35% of active fibroblasts are derived from EMT which is central to the development of progressive renal fibrosis. Hence, this study was designed to assess the effect of miRNA-200b on transforming growth factor-β (TGF-β1)-induced fibrotic responses in renal tubular cells. Morphologically, human kidney-2 cells transfected with miRNA-200b retained their epithelial cell characteristics when exposed to TGF-β1. miRNA-200b significantly increased E-cadherin ( P 〈 0.001) and reduced fibronectin mRNA and protein expression (both P 〈 0.01) independent of phospho-Smad2/3 and phospho-p38 and p42/44 signaling. Increased E-cadherin expression was associated with decreased expression of ZEB1 and ZEB2 and repression of fibronectin was mediated through direct targeting of the fibronectin mRNA, demonstrated using pMIR luciferase reporter assay and site-directed mutagenesis. These results suggest that miRNA-200b suppresses TGF-β1-induced EMT via inhibition of ZEB1 and ZEB2 and the extracellular matrix protein fibronectin by directing targeting of its 3'UTR mRNA, independent of pathways directly involved in TGF-β1 signaling.
    Print ISSN: 1931-857X
    Electronic ISSN: 1522-1466
    Topics: Medicine
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  • 10
    Publication Date: 2013-04-18
    Description: Nebivolol is a selective β1-blocker with nitric oxide–enhancing effects. MicroRNAs are small noncoding RNA molecules that downregulate gene expression. We compared the effects of nebivolol and atenolol, a first generation β1-selective blocker, on left ventricular hypertrophy, fibrosis, and function and microRNA expression in a rodent model of hypertension. Dahl salt-sensitive rats received either low-salt chow (control) or AIN-76A high-salt (8% NaCl) diet and randomized to vehicle (high-salt), nebivolol (20 mg/kg per day), or atenolol (50 mg/kg per day) for 8 weeks. High-salt induced left ventricular hypertrophy and fibrosis and decreased the expression of miR-27a, -29a, and -133a. Nebovolol attenuated deterioration of left ventricular systolic function, remodeling, and fibrosis more than atenolol, despite similar effects on heart rate and blood pressure. Nebivolol, but not atenolol, prevented the decrease in miR-27a and -29a induced by high-salt. Nebivolol and atenolol equally attenuated the decrease in miR-133a. In vitro overexpression of miR-27a,-29a, and -133a inhibited cardiomyocyte hypertrophy and reduced collagen expression. Both miR-27a and -29a target Sp1, and miR-133a targets Cdc42. Pharmacological inhibition of Sp1 and Cdc42 decreased myocardial fibrosis and hypertrophy. Our data support a differential microRNAs expression profile in salt-induced hypertension. Nebivolol substantially attenuated cardiac remodeling, hypertrophy, and fibrosis more than atenolol. These effects are related to attenuation of the hypertension-induced decrease in miR-27a and -29a (with a subsequent decrease in Sp1 expression) and miR-133a (with a subsequent decrease in Cdc42).
    Keywords: Remodeling, Animal models of human disease, Hypertrophy
    Print ISSN: 0194-911X
    Topics: Medicine
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