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  • 1
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 5 ( 2020-02-04), p. 2560-2569
    Kurzfassung: De novo mutations (DNMs), or mutations that appear in an individual despite not being seen in their parents, are an important source of genetic variation whose impact is relevant to studies of human evolution, genetics, and disease. Utilizing high-coverage whole-genome sequencing data as part of the Trans-Omics for Precision Medicine (TOPMed) Program, we called 93,325 single-nucleotide DNMs across 1,465 trios from an array of diverse human populations, and used them to directly estimate and analyze DNM counts, rates, and spectra. We find a significant positive correlation between local recombination rate and local DNM rate, and that DNM rate explains a substantial portion (8.98 to 34.92%, depending on the model) of the genome-wide variation in population-level genetic variation from 41K unrelated TOPMed samples. Genome-wide heterozygosity does correlate with DNM rate, but only explains 〈 1% of variation. While we are underpowered to see small differences, we do not find significant differences in DNM rate between individuals of European, African, and Latino ancestry, nor across ancestrally distinct segments within admixed individuals. However, we did find significantly fewer DNMs in Amish individuals, even when compared with other Europeans, and even after accounting for parental age and sequencing center. Specifically, we found significant reductions in the number of C→A and T→C mutations in the Amish, which seem to underpin their overall reduction in DNMs. Finally, we calculated near-zero estimates of narrow sense heritability ( h 2 ), which suggest that variation in DNM rate is significantly shaped by nonadditive genetic effects and the environment.
    Materialart: Online-Ressource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Sprache: Englisch
    Verlag: Proceedings of the National Academy of Sciences
    Publikationsdatum: 2020
    ZDB Id: 209104-5
    ZDB Id: 1461794-8
    SSG: 11
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: Communications Biology, Springer Science and Business Media LLC, Vol. 5, No. 1 ( 2022-02-15)
    Kurzfassung: Atherosclerosis is a chronic inflammatory condition in which macrophages play a major role. Janus kinase 2 (JAK2) is a pivotal molecule in inflammatory and metabolic signaling, and Jak2 V617F activating mutation has recently been implicated with enhancing clonal hematopoiesis and atherosclerosis. To determine the essential in vivo role of macrophage (M)-Jak2 in atherosclerosis, we generate atherosclerosis-prone ApoE-null mice deficient in M-Jak2. Contrary to our expectation, these mice exhibit increased plaque burden with no differences in macrophage proliferation, recruitment or bone marrow clonal expansion. Notably, M-Jak2-deficient bone marrow derived macrophages show a significant defect in cholesterol efflux. Pharmacologic JAK2 inhibition with ruxolitinib also leads to defects in cholesterol efflux and accelerates atherosclerosis. Liver X receptor agonist abolishes the efflux defect and attenuates the accelerated atherosclerosis that occurs with M-Jak2 deficiency. Macrophages of individuals with the Jak2 V617F mutation show increased efflux which is normalized when treated with a JAK2 inhibitor. Together, M-Jak2-deficiency leads to accelerated atherosclerosis primarily through defects in cholesterol efflux from macrophages.
    Materialart: Online-Ressource
    ISSN: 2399-3642
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2022
    ZDB Id: 2919698-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2012
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 32, No. 4 ( 2012-04), p. 1039-1044
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 32, No. 4 ( 2012-04), p. 1039-1044
    Kurzfassung: Overproduction of intestinally derived apoB-48-containing triglyceride-rich lipoproteins (TRLs) (chylomicrons) has recently been described in type 2 diabetes, as is known for hepatic TRL-apoB-100 (very-low-density lipoprotein) production. Furthermore, insulin acutely inhibits both intestinal and hepatic TRL production, whereas this acute inhibitory effect on very-low-density lipoprotein production is blunted in type 2 diabetes. It is not currently known whether this acute effect on chylomicron production is similarly blunted in humans with type 2 diabetes. Methods and Results— We investigated the effect of acute hyperinsulinemia on TRL metabolism in 18 type 2 diabetic men using stable isotope methodology. Each subject underwent 1 control (saline infusion [SAL]) lipoprotein turnover study followed by a second study, under 1 of the 3 following clamp conditions: (1) hyperinsulinemic-euglycemic, (2) hyperinsulinemic-hyperglycemic, or (3) hyperinsulinemic-euglycemic plus intralipid and heparin. TRL-apoB-48 and TRL-apoB-100 production and clearance rates were not different between SAL and clamp and between the different clamp conditions, except for significantly lower TRL-apoB-100 clearance and production rates in hyperinsulinemic-euglycemic plus intralipid and heparin clamp compared with SAL. Conclusion— This is the first demonstration in individuals with type 2 diabetes that chylomicron production is resistant to the normal acute suppressive effect of insulin. This phenomenon may contribute to the highly prevalent dyslipidemia of type 2 diabetes and potentially to atherosclerosis. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00950209.
    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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  • 4
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2017
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 37, No. 9 ( 2017-09), p. 1776-1781
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 37, No. 9 ( 2017-09), p. 1776-1781
    Kurzfassung: Insulin administered directly into the brain acutely suppresses hepatic glucose production and triglyceride-rich lipoprotein (TRL) secretion in rodents. In addition, intranasally administered insulin, which selectively raises cerebrospinal fluid insulin concentration, suppresses hepatic glucose production in humans; however, its effect on TRL secretion in humans has not previously been examined. In this study, we examined whether intranasal insulin, administered at a dose that has previously been shown to suppress hepatic glucose production, modulates TRL particle secretion by the liver and intestine in humans. Approach and Results— Nine healthy, normolipidemic, and normoglycemic men participated in a study consisting of 2 randomized study arms. Subjects received intranasal lispro insulin (40 IU) or placebo. Because intranasal insulin results in a rapid and transient increase in systemic insulin concentration after administration, we matched systemic insulin concentrations in the 2 study arms by infusing lispro insulin intravenously for 30 minutes together with intranasal placebo administration. Apo (apolipoprotein) B100–containing (hepatically derived) and apoB48-containing (intestinally derived) TRL lipoprotein particle turnover were measured for the ensuing 10 hours under pancreatic clamp conditions and constant fed state, using stable isotope enrichment techniques and multicompartmental modeling. Under these experimental conditions, no significant effects of intranasal insulin versus placebo on TRL apoB100 or B48 concentrations, fractional catabolic rates, or production rates were observed. Conclusions— Insulin delivered intranasally at a dose that has been shown to raise cerebrospinal fluid insulin concentration and suppress hepatic glucose production does not affect TRL particle production by the liver and intestine in healthy men. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT03141827.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2017
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Online-Ressource
    Online-Ressource
    The Endocrine Society ; 2008
    In:  The Journal of Clinical Endocrinology & Metabolism Vol. 93, No. 5 ( 2008-05-01), p. 1722-1729
    In: The Journal of Clinical Endocrinology & Metabolism, The Endocrine Society, Vol. 93, No. 5 ( 2008-05-01), p. 1722-1729
    Kurzfassung: Context: Despite its potent, well-documented insulin-sensitizing effects, rosiglitazone (RSG) does not effectively ameliorate the hypertriglyceridemia of insulin-resistant or diabetic individuals and has even been shown to slightly but significantly increase triglyceride-rich lipoproteins (TRL) in some studies. The mechanism of this effect is currently not known. Objective: We investigated the effect of RSG treatment on TRL metabolism. Design: This was a 12-wk, single-sequence, cross-over study of rosiglitazone vs. placebo for 6 wk. Participants: Participants included 17 nondiabetic men with a broad range of insulin sensitivity. Intervention: Intervention included rosiglitazone 8 mg/d vs. placebo for 6 wk. Main Outcome Measure: TRL metabolism (concentration, production and catabolic rates) was assessed in a constant fed state with a 12-h primed constant infusion of [D3]l-leucine and multicompartmental modeling. Results: RSG treatment resulted in significant insulin sensitization with no change in body weight. Fasting plasma triglyceride (TG) concentration, however, was higher with RSG vs. placebo (P = 0.0006), as were fasting and fed TRL-TG, TRL-apoB-48, and TRL-apoB-100 (fed TRL-apoB-48: 0.93 ± 0.08 vs. 0.76 ± 0.07 mg/dl, P =0.017, and fed TRL-apoB-100: 15.57 ± 0.90 vs. 13.71 ± 1.27 mg/dl, P = 0.029). This small but significant increase in plasma TRL concentration was explained by a tendency for RSG to increase TRL production and reduce particle clearance, as indicated by the significantly increased production to clearance ratios for both apoB-48-containing (0.43 ± 0.03 vs. 0.34 ± 0.03, P = 0.048) and apoB-100-containing (7.0 ± 0.4 vs. 6.2 ± 0.6, P = 0.029) TRL. Conclusion: These data indicate dissociation between the insulin-sensitizing effects of RSG and absence of anticipated reductions in production rates of apoB-100- and apoB-48-containing-TRL particles, which may explain the absence of TG lowering seen in humans treated with this agent.
    Materialart: Online-Ressource
    ISSN: 0021-972X , 1945-7197
    RVK:
    Sprache: Englisch
    Verlag: The Endocrine Society
    Publikationsdatum: 2008
    ZDB Id: 2026217-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    In: Endocrinology, The Endocrine Society, Vol. 145, No. 11 ( 2004-11-01), p. 5006-5012
    Kurzfassung: It is not known whether intestinal lipoprotein production is stimulated by an acute elevation of plasma free fatty acids (FFA). We examined the effect of an intralipid and heparin infusion on the intestinal lipoprotein production rate (PR) in insulin-sensitive [chow-fed (CHOW)], insulin-resistant [60% fructose (FRUC) or 60% fat-fed (FAT)] , and insulin-sensitized [FRUC or FAT plus rosiglitazone (RSG)-treated] Syrian Golden hamsters. After 5 wk of treatment, overnight-fasted hamsters underwent in vivo Triton WR-1339 studies for measurement of apolipoprotein B48 (apoB48) PR in large (Svedberg unit, & gt;400) and small (Svedberg unit, 100–400) lipoprotein fractions, with an antecedent 90-min infusion of 20% intralipid and heparin (IH) to raise plasma FFA levels approximately 5- to 8-fold vs. those in the saline control study. IH markedly increased apoB48 PR in CHOW by 3- to 5-fold, which was confirmed ex vivo in pulse-chase experiments in primary cultured hamster enterocytes. Oleate, but not glycerol, infusion was associated with a similar elevation of apoB48 PR as IH. In FRUC and FAT, basal (saline control) apoB48 PR was approximately 4-fold greater than that in CHOW; there was no additional stimulation with IH in vivo and only minimal additional stimulation ex vivo. RSG partially normalized basal apoB48 PR in FAT and FRUC, and PR was markedly stimulated with IH. We conclude that intestinal lipoprotein production is markedly stimulated by an acute elevation of plasma FFAs in insulin-sensitive hamsters, in which basal production is low, but minimally in insulin-resistant hamsters, in which basal production is already elevated. With RSG treatment, basal PR is partially normalized, and they become more susceptible to the acute FFA stimulatory effect.
    Materialart: Online-Ressource
    ISSN: 0013-7227 , 1945-7170
    Sprache: Englisch
    Verlag: The Endocrine Society
    Publikationsdatum: 2004
    ZDB Id: 2011695-0
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: Endocrinology, The Endocrine Society, Vol. 146, No. 1 ( 2005-01-01), p. 247-255
    Kurzfassung: We investigated whether intestinal lipoprotein overproduction in a fructose-fed, insulin-resistant hamster model is prevented with insulin sensitization. Syrian Golden hamsters were fed either chow, 60% fructose for 5 wk, chow for 5 wk with the insulin sensitizer rosiglitazone added for the last 3 wk, or 60% fructose plus rosiglitazone. In vivo Triton studies showed a 2- to 3-fold increase in the large (Svedberg unit & gt; 400) and smaller (Sf 100–400) triglyceride-rich lipoprotein particle apolipoprotein B48 (apoB48) but not triglyceride secretion with fructose feeding in the fasted state (P & lt; 0.01) and partial normalization with rosiglitazone in fructose-fed hamsters. Ex vivo pulse-chase labeling of enterocytes confirmed the oversecretion of apoB48 lipoproteins with fructose feeding. Intestinal lipoprotein oversecretion was associated with increased expression of microsomal triglyceride transfer protein expression. With rosiglitazone treatment of fructose-fed hamsters, there was approximately 50% reduction in apoB48 secretion from primary cultured enterocytes and amelioration of the elevated microsomal triglyceride transfer protein mass and activity in fructose-fed hamsters. In contrast, in the postprandial state, the major differences between nutritional and drug intervention protocols were evident in triglyceride-rich lipoprotein triglyceride and not apoB48 secretion rates. The data suggest that intestinal lipoprotein overproduction can be ameliorated with the insulin sensitizer rosiglitazone.
    Materialart: Online-Ressource
    ISSN: 0013-7227 , 1945-7170
    Sprache: Englisch
    Verlag: The Endocrine Society
    Publikationsdatum: 2005
    ZDB Id: 2011695-0
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2006
    In:  Arteriosclerosis, Thrombosis, and Vascular Biology Vol. 26, No. 6 ( 2006-06), p. 1357-1363
    In: Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 26, No. 6 ( 2006-06), p. 1357-1363
    Kurzfassung: In the present study, we investigated whether intestinal lipoprotein particle production rate is related to indices of insulin resistance in humans. ApoB-48–containing lipoprotein metabolism was examined in 14 nondiabetic men with a broad range of BMI and insulin sensitivity. We demonstrate that intestinal apoB-48–containing TRL production rate is increased in hyperinsulinemic, insulin-resistant humans.
    Materialart: Online-Ressource
    ISSN: 1079-5642 , 1524-4636
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2006
    ZDB Id: 1494427-3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Online-Ressource
    Online-Ressource
    The Endocrine Society ; 1999
    In:  The Journal of Clinical Endocrinology & Metabolism Vol. 84, No. 3 ( 1999-03-01), p. 1037-1046
    In: The Journal of Clinical Endocrinology & Metabolism, The Endocrine Society, Vol. 84, No. 3 ( 1999-03-01), p. 1037-1046
    Materialart: Online-Ressource
    ISSN: 0021-972X , 1945-7197
    RVK:
    Sprache: Englisch
    Verlag: The Endocrine Society
    Publikationsdatum: 1999
    ZDB Id: 2026217-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Online-Ressource
    Online-Ressource
    Ovid Technologies (Wolters Kluwer Health) ; 2002
    In:  Circulation Vol. 106, No. 23 ( 2002-12-03), p. 2955-2960
    In: Circulation, Ovid Technologies (Wolters Kluwer Health), Vol. 106, No. 23 ( 2002-12-03), p. 2955-2960
    Kurzfassung: Background— HMG-CoA reductase inhibitors reduce the incidence of cardiovascular disease predominantly by their LDL-lowering effect. Recently, there has been great interest in the pleiotropic effects of statins, which appear to differ among the various agents in this class. Unlike other statins, atorvastatin exhibits a decline in its HDL-raising effect at higher doses in humans. Whether atorvastatin-mediated alterations in HDL turnover in vivo contribute to this effect has not previously been investigated. We therefore studied the effect of atorvastatin on HDL apolipoprotein (apo) A-I production and clearance in normolipidemic male New Zealand White rabbits. Methods and Results— Kinetic studies of HDL-apoA-I radiolabeled with 131 I were performed in chow-fed rabbits after 3 weeks of atorvastatin treatment of 5 mg · kg −1 · d −1 (n=7) versus placebo-treated rabbits (n=7). Our results showed a significantly ( P 〈 0.001) more rapid clearance (≈2-fold) of HDL apoA-I in atorvastatin-treated animals compared with the control group (0.121±0.012 versus 0.061±0.004 pools/h, respectively), accompanied by a lesser 48% increase in the apoA-I production rate (3.84±0.38 versus 2.59±0.41 mg · kg −1 · h −1 , P =0.06). Accordingly, plasma apoA-I levels in atorvastatin-treated animals declined significantly ( P 〈 0.05, n=8 animals) after 3 weeks of treatment (173.5±1.8 mg/dL) from baseline values. Conclusions— These data suggest that the effect on apoA-I levels observed with atorvastatin at higher drug doses in humans may be caused at least in part by enhanced HDL apoA-I catabolism, which is not entirely offset by a concomitant increase in apoA-I production. Whether this finding results from an effect of atorvastatin on HDL particle composition or on receptors involved in circulating HDL holoparticle clearance will require further study.
    Materialart: Online-Ressource
    ISSN: 0009-7322 , 1524-4539
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 2002
    ZDB Id: 1466401-X
    Standort Signatur Einschränkungen Verfügbarkeit
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