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  • 1
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2016
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 36, No. suppl_1 ( 2016-05)
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 36, No. suppl_1 ( 2016-05)
    Kurzfassung: Despite its putative cardioprotective qualities, raising plasma high density lipoprotein-cholesterol (HDL-C) levels via pharmacologic means has failed to add protection against atherosclerosis, particularly when used as co-therapy with a statin. Two scenarios argue against the raising-plasma-HDL-is-better hypothesis and suggest that enhancing the final RCT step, hepatic cholesterol disposal, is a better cardioprotective strategy. First, probucol prevents CVD events and increases survival in humans and reduces CVD in SR-BI/apo E DKO mice. Despite its anti atherogenic properties, probucol lowers plasma HDL-C levels. Second, SR-BI over expressing vs. WT mice have lower plasma HDL-C but less atherosclerosis whereas the converse is true in SR-BI KO mice, suggesting that increasing HDL-C disposal is a rational cardioprotective strategy. One possible agent for therapeutic development is streptococcal serum opacity factor (SOF), a 100 kDa protein that clouds human serum via a novel HDL-targeting mechanism. SOF diverts HDL-CE to the LDL receptor and to bile acid secretion in vitro and in vivo, increases plasma HDL-C clearance in mice in an apo E-, LDLR-dependent mechanism thereby increasing hepatic CE uptake and reducing plasma cholesterol levels. SOF is active at 10 -14 M. Given its novel mechanism and potent reduction of plasma cholesterol levels in mice, we studied the structure and stability of SOF using its activity as a marker of its integrity versus several physicochemical challenges—extremes of pH, the denaturant, guanidinium chloride, heat, and ionic strength. SOF was highly resistant to all of these challenges. SOF has only one cysteine so it cannot be stabilized by internal disulfide bonds. Thus, SOF is an unusually stable protein that undergoes reversible unfolding-folding when challenged with a variety of physicochemical perturbants. These studies have helped us identify optimal conditions for crystallizing SOF for X-ray structure analysis.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2016
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2012
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 32, No. suppl_1 ( 2012-05)
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 32, No. suppl_1 ( 2012-05)
    Kurzfassung: Background: Microsolubilization of dimyristoyl phosphatidylcholine (DMPC) by human apolipoprotein A-I is a frequently used model system for the identification of determinants of macrophage cholesterol efflux, the first step in reverse cholesterol transport (RCT) to hepatic disposal. Although many studies have focused on microsolubilization of DMPC, most have been conducted under stoichiometric conditions resulting in ∼9 nm rHDL, and few have included free cholesterol (FC), a key lipid in RCT. Methods: Various rHDL species (excess DMPC + FC), were prepared and analyzed by size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy as a function of temperature. Results: At each mol% of FC/DMPC, multiple rHDL species differing in size from ∼10 to ∼25 nm were formed. In SEC, rHDL size increased with the mol% FC in the microsolubilization reaction and in a given reaction mixture the large rHDL were always more FC-rich than the small rHDL. In DSC, the DMPC transition range of rHDL was broader than that of pure DMPC and although the transition temperature moderately increases with increasing mol% FC, the apparent enthalpy of the transition is diminished. The thermal dependence of the CD spectra showed that increasing mol% FC and rHDL size moderately increases the stability of apo A-I. Conclusion: Although large FC-rich and small FC-poor domains coexist on DMPC surfaces; the size of these domains increases with mol% FC. This effect of FC on rHDL size decreases the overall cooperativity of the DMPC phase transition and reduces the number of acyl chain interactions. Physiologically, these data suggest that increased FC-loading of macrophages should increase the size of nascent HDL produced by the interaction of apo A-I with cellular ABCA1. The lower stability of FC-poor HDL would likely make it release more lipid-free apo A-I in response to important plasma proteins including LCAT, PLTP, and CETP and in response to serum opacity factor.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2012
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2022
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 42, No. Suppl_1 ( 2022-05)
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 42, No. Suppl_1 ( 2022-05)
    Kurzfassung: Aim: In humans, very high plasma HDL-cholesterol concentrations are associated with increased all cause- and atherosclerotic cardiovascular disease (ASCVD)-mortality. The HDL receptor-deficient mouse (Scarb1 -/- ) is a robust model of this phenotype having high free cholesterol (FC) bioavailability due to too many FC-rich HDL particles. Clinically, plasma LDL and HDL are quantified according to total cholesterol = FC + cholesteryl esters (CE), which likely contribute to ASCVD pathophysiology differently. Despite higher HDL, Scarb1 -/- mice have more ASCVD on a Western diet, and increased mol% FC in ovaries, erythrocytes, heart, lung, female liver and macrophages, tissues that are associated with female infertility, impaired cell maturation, cardiac dysfunction and atherosclerosis. Bacterial serum opacity factor (SOF) reduces plasma cholesterol ~ 40% by diverting HDL-cholesterol to the hepatic LDLR. Hypothesis: Adeno-associated virus delivery of SOF (AAV SOF ) normalizes plasma and tissue FC accretion and reverses the pathologies associated with Scarb1 -/- mice. Methods: The lipid compositions of plasma, HDL, erythrocytes, and tissues of Scarb1 -/- mice treated with AAV SOF at 12-13 weeks of age for three weeks were compared with age- and sex-matched wild type (WT) C57BL6 and Scarb1 -/- mice. Results: As hypothesized, AAV SOF reduced plasma and HDL-FC and CE, as well as mol% FC in Scarb1 -/- mice towards WT levels. Erythrocyte FC levels also fell, but mol% FC remained elevated. Some changes were sex-specific: AAV SOF reduced the elevated FC only in female livers to WT levels. AAV SOF reduced FC and CE in lungs of females to WT levels, but not among males; the mol% FC remained high in both sexes. In steroidogenic tissues, adrenals, ovaries and testis, AAV SOF treatment increased FC. Unexpectedly, in Scarb1 -/- mice, AAV SOF increased mol% FC and FC in heart beyond already elevated levels. Conclusions: These findings support the hypothesis that plasma and HDL cholesterol levels determine tissue cholesterol levels that drive the pathologies specific to Scarb1 -/- mice. This evolving model of the role of HDL-FC in RCT provides a rationale for human studies to determine the utility of HDL-FC bioavailability as a risk factor for ASCVD and other pathologies.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2022
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2021
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 41, No. Suppl_1 ( 2021-09)
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 41, No. Suppl_1 ( 2021-09)
    Kurzfassung: Aim: In humans, very high plasma HDL-cholesterol concentrations are associated with increased all cause- and atherosclerotic cardiovascular disease (ASCVD)-mortality. The HDL receptor-deficient mouse (Scarb1 -/- ), a robust model of this phenotype, is characterized by high free cholesterol (FC) bioavailability due to too many HDL particles that are FC-rich. Clinically, plasma LDL and HDL are quantified according to total cholesterol content, the sum of FC and esterified cholesterol, which likely contribute to ASCVD pathophysiology differently. A Western diet induces ASCVD in Scarb1 -/- mice, despite an attendant increase in HDL. We tested the hypothesis that high HDL-FC bioavailability contributes to ASCVD in Scarb1 -/- mice by increasing FC flux into macrophage cells, erythrocytes and other major tissues. Methods: Influx of HDL-FC and efflux of macrophage FC were determined between WT and Scarb1 -/- HDL and J774 macrophage cells. HDL of both genotypes were radiolabelled with [ 3 H]FC, injected into autologous mice, and the rates of plasma clearance and erythrocyte uptake were determined. Results: The magnitude of FC transfer from Scarb1 -/- HDL to LDL is greater than that from WT HDL; APOB-containing lipoproteins from Scarb1 -/- vs. WT mice are FC-enriched due likely to greater HDL-FC transfer. While macrophage efflux to HDL of Scarb1 -/- vs. WT HDL was not different, FC influx from Scarb1 -/- vs. WT HDL to macrophages was three-fold greater, a net effect that increased the FC burden of macrophages. In vivo studies showed that compared to WT mice, in Scarb1 -/- mice, autologous HDL-FC cleared more slowly and more FC transferred to erythrocytes. We compared the FC, CE, PL, and TG contents of all major tissues and determined that FC accretion by some tissues is higher among Scarb1 -/- vs. WT mice whereas in other tissues FC homeostasis is maintained. Lastly, we determined that the tissue compositions and plasma FC clearance kinetics varied according to sex, particularly among Scarb1 -/- mice. Conclusions: These findings are relevant to pathologies specific to Scarb1 -/- mice and to the evolving model of the role of HDL-FC in RCT. They provide a rationale for human studies to determine the utility of HDL-FC bioavailability as a risk factor for ASCVD and other pathologies.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2021
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2023
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 43, No. Suppl_1 ( 2023-05)
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 43, No. Suppl_1 ( 2023-05)
    Kurzfassung: Compared to wild-type mice, HDL-receptor-deficient (Scarb1 -/- ) mice have higher plasma levels of free cholesterol (FC)-rich HDL and exhibit multiple pathologies—female infertility and deranged platelet and erythrocyte morphology and function. These pathologies are associated with a low mol% FC in ovaries, platelets, and erythrocytes, effects that are reversed by the HDL-lowering drug probucol. Some strains of Streptococcus pyogenes secrete a protein, serum opacity factor (SOF), which catalyzes the clouding i.e., opacification, of plasma. SOF specifically targets and quantitatively converts HDL into three products, that include a cholesteryl ester-rich microemulsion containing all the cholesterol content of 〉 100,000 HDL particles as well as APOE and its heterodimer with APOA2 as its sole apolipoproteins. Delivery of SOF with an adeno-associated virus (AAV SOF ) constitutively lowers plasma HDL-FC and reverses female infertility in Scarb1 -/- mice. Thus, we tested the hypothesis—AAV SOF delivery to Scarb1 -/- mice will normalize erythrocyte morphology in an HDL-FC dependent way. The erythrocyte morphology and FC content expressed as mol% FC of three groups of mice—WT, untreated Scarb1 -/- mice (control) and Scarb1 -/- mice receiving AAV SOF —were compared and correlated with their respective HDL-mol% FC. Among Scarb1 -/- mice, AAV SOF treatment normalized reticulocyte number, erythrocyte morphology and erythrocyte mol% FC. Plasma- and HDL-mol% FC positively correlated (p 〈 0.0001) across all three groups of mice. HDL-mol% FC also positively correlated with erythrocyte mol% FC (p 〈 0.0001). Finally, the erythrocyte mol% FC positively correlated with both the number of reticulocytes (p = 0.006) and abnormal erythrocytes (p 〈 0.0001). Although less profound, AAV SOF treatment also reduced the FC contents of some extravascular tissues. HDL-FC spontaneously transfers from plasma lipoproteins to cell membranes in multiple tissues sites on a time scale of minutes to a few hours. FC-enrichment of erythrocytes, which are in contact with plasma HDL, was more profound than FC enrichment in tissues. AAV SOF treatment lowers both plasma HDL-FC and erythrocyte-FC and normalizes erythrocyte morphology and lipid composition in an HDL-FC dependent way.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2023
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    In: Journal of Clinical Lipidology, Elsevier BV, Vol. 10, No. 3 ( 2016-05), p. 679-680
    Materialart: Online-Ressource
    ISSN: 1933-2874
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2016
    ZDB Id: 2365061-8
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: Atherosclerosis, Elsevier BV, Vol. 223, No. 2 ( 2012-08), p. 342-349
    Materialart: Online-Ressource
    ISSN: 0021-9150
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2012
    ZDB Id: 1499887-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Online-Ressource
    Online-Ressource
    Elsevier BV ; 2017
    In:  Atherosclerosis Vol. 263 ( 2017-08), p. e75-
    In: Atherosclerosis, Elsevier BV, Vol. 263 ( 2017-08), p. e75-
    Materialart: Online-Ressource
    ISSN: 0021-9150
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2017
    ZDB Id: 1499887-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
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    Elsevier BV ; 2017
    In:  Atherosclerosis Vol. 263 ( 2017-08), p. e214-
    In: Atherosclerosis, Elsevier BV, Vol. 263 ( 2017-08), p. e214-
    Materialart: Online-Ressource
    ISSN: 0021-9150
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2017
    ZDB Id: 1499887-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    In: Biochemistry, American Chemical Society (ACS), Vol. 48, No. 7 ( 2009-02-24), p. 1481-1487
    Materialart: Online-Ressource
    ISSN: 0006-2960 , 1520-4995
    RVK:
    Sprache: Englisch
    Verlag: American Chemical Society (ACS)
    Publikationsdatum: 2009
    ZDB Id: 1472258-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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