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Ekström L, Kaigle Holm A, Hansson T, Holm S. Intradiscal pressure in the degenerated porcine intervertebral disc. Vet Comp Orthop Traumatol 2017. [DOI: 10.1055/s-0037-1616584] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
SummaryMeasuring intradiscal pressure is one way of mechanically assessing the discs degenerative state. In this study, the load-bearing capacity of degenerated and their adjacent lumbar intervertebral discs was evaluated using two different injury models. Seventeen adolescent pigs were divided into two groups, an annulus injury group and an endplate injury group. The annulus injury group was subjected to a stab incision in the L3-L4 disc, whereas the endplate injury group received a cranial endplate perforation of the L4 vertebral body. Both groups were biomechanically evaluated three months later using a miniaturized servohydraulic testing machine across L2-L4 and with two pressure needles inserted into the nucleus pulposus of the L2-L3 and L3-L4 discs. Linear relationships between the intradiscal pressure and the applied load were determined within the load range studied. When comparing the ratio of the injured to the adjacent disc pressure, the endplate injury was lower (mean value 0.31) than the annulus injury (mean value 0.51). The pressures in the discs adjacent to the degenerated level were found to be slightly higher. This increase can be expected due to a redistribution in mobility demands in segments adjacent to those with increased stiffness, i.e. degenerated intervertebral discs.
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Baranto A, Kaigle Holm A, Ekström L, Swärd L, Hansson T, Hansson HA, Holm S. Reactive changes in the adolescent porcine spine with disc degeneration due to endplate injury. Vet Comp Orthop Traumatol 2017. [DOI: 10.1055/s-0037-1616581] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
SummaryDegenerative and reactive structural alterations occurring after experimentally-induced disc degeneration were evaluated using a porcine model. A cranial perforation was made through the L4 vertebral endplate into the nucleus pulposus. Three months later, the lumbar intervertebral disc and adjacent vertebrae were dissected, fixed in formalin and further processed for histopathological analyses. The results showed that there were nucleus pulposus fragments, rather than a distinct border between the nucleus and annulus fibrosus. The central lamellae were distorted and delamination of the outer anterior layers was observed. Blood vessels emerged from the adjacent tissue, penetrated the annulus and branched into the residues of the nucleus. Nerve fibres accompanying the blood vessels could be recognized in the disc within the connective scar tissue. The epiphyseal cartilage plates in the vertebrae were hypertrophic in several areas and there was bone formation directed towards the centre of the vertebral body and the disc. Hypertrophic hyaline cartilage, newly formed bone and scar tissue filled the injury canal. A slight chronic inflammatory reaction was evident along vascular buds. The reactive changes dominated over the degenerated features in the operated disc. Physiological loading enhanced the infiltration of various tissue types characterizing immature cartilage formation. Prominent neovascularisation of the central parts of the disc is likely to be of key importance in turning the degenerative features of the remaining tissue into reactive healthy structures.
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Gregersen I, Sandanger Ø, Askevold ET, Sagen EL, Yang K, Holm S, Pedersen TM, Skjelland M, Krohg-Sørensen K, Hansen TV, Dahl TB, Otterdal K, Espevik T, Aukrust P, Yndestad A, Halvorsen B. Interleukin 27 is increased in carotid atherosclerosis and promotes NLRP3 inflammasome activation. PLoS One 2017; 12:e0188387. [PMID: 29176764 PMCID: PMC5703457 DOI: 10.1371/journal.pone.0188387] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 11/06/2017] [Indexed: 11/19/2022] Open
Abstract
Aim Interleukin-27 (IL-27) is involved in different inflammatory diseases; however, its role in atherosclerosis is unclear. In this study we investigated the expression of IL-27 and its receptor in patients with carotid atherosclerosis and if IL-27 could modulate the inflammatory effects of the NLRP3 inflammasome in vitro. Methods Plasma IL-27 was measured by enzyme immunoassay in patients with carotid stenosis (n = 140) and in healthy controls (n = 19). Expression of IL-27 and IL-27R was analyzed by quantitative PCR and immunohistochemistry in plaques from patients and in non-atherosclerotic vessels. THP-1 monocytes, primary monocytes and peripheral blood mononuclear cells (PBMCs) were used to study effects of IL-27 in vitro. Results Our main findings were: (i) Plasma levels of IL-27 were significantly elevated in patients with carotid atherosclerotic disease compared to healthy controls. (ii) Gene expression of IL-27 and IL-27R was significantly elevated in plaques compared to control vessels, and co-localized to macrophages. (iii) In vitro, IL-27 increased NLRP3 inflammasome activation in monocytes with enhanced release of IL-1 β. Conclusions We demonstrate increased levels of IL-27 and IL-27R in patients with carotid atherosclerosis. Our in vitro findings suggest an inflammatory role for IL-27, which can possibly be linked to atherosclerotic disease development.
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Holm S, Holm MB. Restrictions on wave equations for passive media. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:1888. [PMID: 29092559 DOI: 10.1121/1.5006059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Most derivations of acoustic wave equations involve ensuring that causality is satisfied. Here, the consequences of also requiring that the medium should be passive are explored. This is a stricter criterion than causality for a linear system and implies that there are restrictions on the relaxation modulus and its first few derivatives. The viscous and relaxation models of acoustics satisfy passivity and have restrictions on not only a few, but all derivatives of the relaxation modulus. These models are described as a system of springs and dampers with positive parameters and belong to the important class of completely monotone systems. It is shown here that the attenuation as a function of frequency for such media has to increase slower than a linear function. Likewise, the phase velocity has to increase monotonically. This gives criteria on which one may judge whether a proposed wave equation is passive or not, as illustrated by comparing two different versions of the viscous wave equation.
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Rindal OMH, Aakhus S, Holm S, Austeng A. Hypothesis of Improved Visualization of Microstructures in the Interventricular Septum with Ultrasound and Adaptive Beamforming. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2494-2499. [PMID: 28689675 DOI: 10.1016/j.ultrasmedbio.2017.05.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/24/2017] [Accepted: 05/27/2017] [Indexed: 06/07/2023]
Abstract
In this work, in vivo ultrasound cardiac images created with Capon's minimum variance adaptive beamformer are compared with images acquired with the conventional delay-and-sum beamformer. Specifically, we provide three views of a human heart imaged through the parasternal short-axis, the parasternal long-axis and the apical four-chamber views. The minimum variance beamformer produced images with improved lateral resolution, resulting in better resolved speckle structure and improved edges, especially on close investigation of the interventricular septum. These improvements in image quality might possibly improve the visualization of microstructures in the human heart.
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Espada S, Stavik B, Holm S, Sagen EL, Bjerkeli V, Skjelland M, Dahl TB, Espevik T, Kanse S, Sandset PM, Skretting G, Halvorsen B. Tissue factor pathway inhibitor attenuates ER stress-induced inflammation in human M2-polarized macrophages. Biochem Biophys Res Commun 2017; 491:442-448. [PMID: 28712870 DOI: 10.1016/j.bbrc.2017.07.070] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 07/12/2017] [Indexed: 01/08/2023]
Abstract
Endoplasmic reticulum (ER) stress has been shown to play a key role during the initiation and clinical progression of the cardiovascular diseases, such as atherosclerosis. We have recently shown that expression of tissue factor pathway inhibitor (TFPI) in human monocyte-derived macrophages (MDMs) was induced by cholesterol crystals (CC). In the present study we aimed to determine the role of TFPI under ER stress conditions using human MDMs. qRT-PCR and immunohistochemistry analysis were performed to determine the presence of the ER stress marker CCAAT/enhancer binding protein homologous protein (CHOP) and TFPI in human carotid plaque material and also in human MDMs polarized into pro-inflammatory M1 or anti-inflammatory M2 populations. CHOP mRNA levels were upregulated in the plaques compared to healthy vessels, and CHOP protein was localized in the same area as TFPI in the plaques. Both CHOP and TFPI mRNA levels were upregulated after CC treatment, especially in the M2 phenotype, and the ER stress inhibitor 4-phenylbutyric acid (PBA) reversed this effect. Furthermore, CC treatment increased the levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-8, which for TNF-α and IL-8 was inhibited by PBA, and reduced the levels of the anti-inflammatory cytokine IL-10 in M2-polarized macrophages. Knockdown of TFPI prior to CC treatment exacerbated TNF-α and IL-6 levels, but reduced IL-8 and IL-10 levels. Our results show that CC induce TFPI and cytokine expression in M2-polarized macrophages through activation of the ER stress pathway and that TFPI has a protective effect against TNF-α and IL-6 mediated inflammation. These mechanisms may have implications for the pathogenesis of atherosclerosis.
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Stavik B, Holm S, Espada S, Iversen N, Sporsheim B, Bjerkeli V, Dahl TB, Sandset PM, Skjelland M, Espevik T, Skretting G, Halvorsen B. Increased expression of TFPI in human carotid stenosis. Thromb Res 2017; 155:31-37. [PMID: 28482260 DOI: 10.1016/j.thromres.2017.04.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/04/2017] [Accepted: 04/25/2017] [Indexed: 01/20/2023]
Abstract
INTRODUCTION Tissue factor (TF) pathway inhibitor (TFPI) is the physiological inhibitor of TF induced blood coagulation and two isoforms exists, TFPIα and TFPIβ. In atherosclerotic plaques, TFPI may inhibit TF activity and thrombus formation, which is the main cause of ischemic stroke in carotid artery disease. We aimed to identify the isoforms of TFPI present in human carotid plaques and potential sources of TFPI. MATERIALS AND METHODS Human atherosclerotic plaques from carotid endarterectomies were used for mRNA and immunohistochemistry analyses. hPBMCs isolated from buffy coats and THP-1 cells were differentiated and polarized into M1 or M2 macrophages, and subsequently cultured with or without cholesterol crystals (CC). mRNA and protein expression were measured with qRT-PCR and ELISA, respectively, and procoagulant activity was assessed using a two-stage chromogenic assay. RESULTS TFPIα and TFPIβ mRNA levels were significantly increased in carotid plaques, whereas TF levels were unchanged as compared to healthy arteries. Antibodies against total TFPI showed elevated levels compared to antibodies against free TFPIα, both by immunohistochemical and ELISA detection in plaques. The antibody against total TFPI also co-localized with CD68 and the M1 and M2 markers CD80 and CD163, respectively. The TFPI mRNA expression was elevated and the procoagulant activity was decreased in M2 compared to M1 polarized human macrophages. TFPI was present in early foam cell formation and CC treatment increased the TFPI mRNA expression even further in M2 macrophages. CONCLUSIONS Our data indicate that both isoforms of TFPI are present in advanced plaques and that anti-inflammatory M2 macrophages may be a potential source of TFPI.
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Chen W, Fang J, Pang G, Holm S. Fractional biharmonic operator equation model for arbitrary frequency-dependent scattering attenuation in acoustic wave propagation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:244. [PMID: 28147566 DOI: 10.1121/1.4973865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This paper proposes a fractional biharmonic operator equation model in the time-space domain to describe scattering attenuation of acoustic waves in heterogeneous media. Compared with the existing models, the proposed fractional model is able to describe arbitrary frequency-dependent scattering attenuation, which typically obeys an empirical power law with an exponent ranging from 0 to 4. In stark contrast to an extensive and rapidly increasing application of the fractional derivative models for wave absorption attenuation in the literature, little has been reported on frequency-dependent scattering attenuation. This is largely because the order of the fractional Laplacian is from 0 to 2 and is infeasible for scattering attenuation. In this study, the definition of the fractional biharmonic operator in space with an order varying from 0 to 4 is proposed, as well as a fractional biharmonic operator equation model of scattering attenuation which is consistent with arbitrary frequency power-law dependency and obeys the causal relation under the smallness approximation. Finally, the correlation between the fractional order and the ratio of wavelength to the diameter of the scattering heterogeneity is investigated and an expression on exponential form is also provided.
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Pandey V, Holm S. Connecting the grain-shearing mechanism of wave propagation in marine sediments to fractional order wave equations. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:4225. [PMID: 28039990 DOI: 10.1121/1.4971289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The characteristic time-dependent viscosity of the intergranular pore-fluid in Buckingham's grain-shearing (GS) model [Buckingham, J. Acoust. Soc. Am. 108, 2796-2815 (2000)] is identified as the property of rheopecty. The property corresponds to a rare type of a non-Newtonian fluid in rheology which has largely remained unexplored. The material impulse response function from the GS model is found to be similar to the power-law memory kernel which is inherent in the framework of fractional calculus. The compressional wave equation and the shear wave equation derived from the GS model are shown to take the form of the Kelvin-Voigt fractional-derivative wave equation and the fractional diffusion-wave equation, respectively. Therefore, an analogy is drawn between the dispersion relations obtained from the fractional framework and those from the GS model to establish the equivalence of the respective wave equations. Further, a physical interpretation of the characteristic fractional order present in the wave equations is inferred from the GS model. The overall goal is to show that fractional calculus is not just a mathematical framework which can be used to curve-fit the complex behavior of materials. Rather, it can also be derived from real physical processes as illustrated in this work by the example of GS.
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Lunde NN, Holm S, Dahl TB, Elyouncha I, Sporsheim B, Gregersen I, Abbas A, Skjelland M, Espevik T, Solberg R, Johansen HT, Halvorsen B. Increased levels of legumain in plasma and plaques from patients with carotid atherosclerosis. Atherosclerosis 2016; 257:216-223. [PMID: 27940038 DOI: 10.1016/j.atherosclerosis.2016.11.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/14/2016] [Accepted: 11/23/2016] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND AIMS The cysteine protease legumain has been shown to be up-regulated in unstable atherosclerotic plaques. This study aims to further elucidate legumain in atherosclerosis, by examining legumain in plasma and carotid plaques from patients with carotid stenosis. Furthermore, legumain secretion from monocyte-derived macrophages treated with atherogenic lipids during macrophage polarization was studied. METHODS Plasma levels of legumain from patients with carotid stenosis (n = 254), healthy controls (n = 91), and secreted from monocyte-derived macrophages were assessed by enzyme-linked-immunosorbent assay. Quantitative PCR and immunoblotting of legumain were performed on isolated plaques and legumain localization was visualized by immunohistochemistry and fluorescence microscopy. Monocyte-derived macrophages polarized to M1 or M2 macrophages were treated with VLDL, oxLDL or cholesterol crystals (CC) and the level of legumain analysed. RESULTS Patients with carotid stenosis had significantly higher levels of plasma legumain compared with healthy controls (median 2.0 versus 1.5 ng/ml, respectively; p = 0.003), although there was no correlation between the level of legumain and the degree of stenosis, and legumain was not an independent factor to identify patients with carotid plaques. Moreover, patients with symptoms the last 2 months had higher expressions of mature legumain, cystatin C and E/M, and the macrophage markers CD80 (M1) and CD163 (M2). Legumain co-localized with both M1 and M2 macrophages within plaques, whereas legumain mRNA expression was significantly higher (p < 0.0001) in plaques compared to non-atherosclerotic arteries (controls). Furthermore, in vitro studies showed significantly increased secretion of legumain from pro-inflammatory M1 compared to pro-resolving M2 macrophages (p = 0.014), and particularly in M1 treated with CC. In plaques, legumain was localized to structures resembling foam cells. CONCLUSIONS Legumain is increased in both plasma and plaques of patients with carotid stenosis and might be a new and early biomarker of atherosclerosis.
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Pilely K, Rosbjerg A, Genster N, Gal P, Pál G, Halvorsen B, Holm S, Aukrust P, Bakke SS, Sporsheim B, Nervik I, Niyonzima N, Bartels ED, Stahl GL, Mollnes TE, Espevik T, Garred P. Cholesterol crystals activate the lectin complement pathway via ficolin-2 and MBL – Implications for the progression of atherosclerosis. Immunobiology 2016. [DOI: 10.1016/j.imbio.2016.06.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Pandey V, Holm S. Linking the fractional derivative and the Lomnitz creep law to non-Newtonian time-varying viscosity. Phys Rev E 2016; 94:032606. [PMID: 27739858 DOI: 10.1103/physreve.94.032606] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Indexed: 11/07/2022]
Abstract
Many of the most interesting complex media are non-Newtonian and exhibit time-dependent behavior of thixotropy and rheopecty. They may also have temporal responses described by power laws. The material behavior is represented by the relaxation modulus and the creep compliance. On the one hand, it is shown that in the special case of a Maxwell model characterized by a linearly time-varying viscosity, the medium's relaxation modulus is a power law which is similar to that of a fractional derivative element often called a springpot. On the other hand, the creep compliance of the time-varying Maxwell model is identified as Lomnitz's logarithmic creep law, making this possibly its first direct derivation. In this way both fractional derivatives and Lomnitz's creep law are linked to time-varying viscosity. A mechanism which yields fractional viscoelasticity and logarithmic creep behavior has therefore been found. Further, as a result of this linking, the curve-fitting parameters involved in the fractional viscoelastic modeling, and the Lomnitz law gain physical interpretation.
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Holm S, Davis RB, Javoiš J, Õunap E, Kaasik A, Molleman F, Tammaru T. A comparative perspective on longevity: the effect of body size dominates over ecology in moths. J Evol Biol 2016; 29:2422-2435. [PMID: 27536807 DOI: 10.1111/jeb.12966] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 01/06/2023]
Abstract
Both physiologically and ecologically based explanations have been proposed to account for among-species differences in lifespan, but they remain poorly tested. Phylogenetically explicit comparative analyses are still scarce and those that exist are biased towards homoeothermic vertebrates. Insect studies can significantly contribute as lifespan can feasibly be measured in a high number of species, and the selective forces that have shaped it may differ largely between species and from those acting on larger animals. We recorded adult lifespan in 98 species of geometrid moths. Phylogenetic comparative analyses were applied to study variation in species-specific values of lifespan and to reveal its ecological and life-history correlates. Among-species and between-gender differences in lifespan were found to be notably limited; there was also no evidence of phylogenetic signal in this trait. Larger moth species were found to live longer, with this result supporting a physiological rather than ecological explanation of this relationship. Species-specific lifespan values could not be explained by traits such as reproductive season and larval diet breadth, strengthening the evidence for the dominance of physiological determinants of longevity over ecological ones.
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Adams MA, Hult E, Ekström L, Kaigle A, Holm S, Hansson T. In Vivo Measurement of Spinal Column Viscoelasticity—An Animal Model. Proc Inst Mech Eng H 2016. [DOI: 10.1243/pime_proc_1995_209_331_02] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Skarpengland T, Dahl TB, Skjelland M, Scheffler K, de Sousa MML, Gregersen I, Kuśnierczyk A, Sharma A, Slupphaug G, Eide L, Segers FM, Skagen KR, Dahl CP, Russell D, Folkersen L, Krohg-Sørensen K, Holm S, Bjørås M, Aukrust P, Halvorsen B. Enhanced base excision repair capacity in carotid atherosclerosis may protect nuclear DNA but not mitochondrial DNA. Free Radic Biol Med 2016; 97:386-397. [PMID: 27381496 DOI: 10.1016/j.freeradbiomed.2016.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/13/2016] [Accepted: 07/01/2016] [Indexed: 01/05/2023]
Abstract
BACKGROUND Lesional and systemic oxidative stress has been implicated in the pathogenesis of atherosclerosis, potentially leading to accumulation of DNA base lesions within atherosclerotic plaques. Although base excision repair (BER) is a major pathway counteracting oxidative DNA damage, our knowledge on BER and accumulation of DNA base lesions in clinical atherosclerosis is scarce. Here, we evaluated the transcriptional profile of a wide spectrum of BER components as well as DNA damage accumulation in atherosclerotic and non-atherosclerotic arteries. METHODS BER gene expression levels were analyzed in 162 carotid plaques, 8 disease-free carotid specimens from patients with carotid plaques and 10 non-atherosclerotic control arteries. Genomic integrity, mitochondrial (mt) DNA copy number, oxidative DNA damage and BER proteins were evaluated in a subgroup of plaques and controls. RESULTS Our major findings were: (i) The BER pathway showed a global increased transcriptional response in plaques as compared to control arteries, accompanied by increased expression of several BER proteins. (ii) Whereas nuclear DNA stability was maintained within carotid plaques, mtDNA integrity and copy number were decreased. (iii) Within carotid plaques, mRNA levels of several BER genes correlated with macrophage markers. (iv) In vitro, some of the BER genes were highly expressed in the anti-inflammatory and pro-resolving M2 macrophages, showing increased expression upon exposure to modified lipids. CONCLUSIONS The increased transcriptional response of BER genes in atherosclerosis may contribute to lesional nuclear DNA stability but appears insufficient to maintain mtDNA integrity, potentially influencing mitochondrial function in cells within the atherosclerotic lesion.
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Skarpengland T, Holm S, Scheffler K, Gregersen I, Dahl TB, Suganthan R, Segers FM, Østlie I, Otten JJT, Luna L, Ketelhuth DFJ, Lundberg AM, Neurauter CG, Hildrestrand G, Skjelland M, Bjørndal B, Svardal AM, Iversen PO, Hedin U, Nygård S, Olstad OK, Krohg-Sørensen K, Slupphaug G, Eide L, Kuśnierczyk A, Folkersen L, Ueland T, Berge RK, Hansson GK, Biessen EAL, Halvorsen B, Bjørås M, Aukrust P. Neil3-dependent base excision repair regulates lipid metabolism and prevents atherosclerosis in Apoe-deficient mice. Sci Rep 2016; 6:28337. [PMID: 27328939 PMCID: PMC4916448 DOI: 10.1038/srep28337] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/01/2016] [Indexed: 12/23/2022] Open
Abstract
Increasing evidence suggests that oxidative DNA damage accumulates in atherosclerosis. Recently, we showed that a genetic variant in the human DNA repair enzyme NEIL3 was associated with increased risk of myocardial infarction. Here, we explored the role of Neil3/NEIL3 in atherogenesis by both clinical and experimental approaches. Human carotid plaques revealed increased NEIL3 mRNA expression which significantly correlated with mRNA levels of the macrophage marker CD68. Apoe−/−Neil3−/− mice on high-fat diet showed accelerated plaque formation as compared to Apoe−/− mice, reflecting an atherogenic lipid profile, increased hepatic triglyceride levels and attenuated macrophage cholesterol efflux capacity. Apoe−/−Neil3−/− mice showed marked alterations in several pathways affecting hepatic lipid metabolism, but no genotypic alterations in genome integrity or genome-wide accumulation of oxidative DNA damage. These results suggest a novel role for the DNA glycosylase Neil3 in atherogenesis in balancing lipid metabolism and macrophage function, potentially independently of genome-wide canonical base excision repair of oxidative DNA damage.
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Pilely K, Rosbjerg A, Genster N, Gal P, Pál G, Halvorsen B, Holm S, Aukrust P, Bakke SS, Sporsheim B, Nervik I, Niyonzima N, Bartels ED, Stahl GL, Mollnes TE, Espevik T, Garred P. Cholesterol Crystals Activate the Lectin Complement Pathway via Ficolin-2 and Mannose-Binding Lectin: Implications for the Progression of Atherosclerosis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:5064-74. [PMID: 27183610 DOI: 10.4049/jimmunol.1502595] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 04/13/2016] [Indexed: 12/16/2023]
Abstract
Cholesterol crystals (CC) play an essential role in the formation of atherosclerotic plaques. CC activate the classical and the alternative complement pathways, but the role of the lectin pathway is unknown. We hypothesized that the pattern recognition molecules (PRMs) from the lectin pathway bind CC and function as an upstream innate inflammatory signal in the pathophysiology of atherosclerosis. We investigated the binding of the PRMs mannose-binding lectin (MBL), ficolin-1, ficolin-2, and ficolin-3, the associated serine proteases, and complement activation products to CC in vitro using recombinant proteins, specific inhibitors, as well as deficient and normal sera. Additionally, we examined the deposition of ficolin-2 and MBL in human carotid plaques by immunohistochemistry and fluorescence microscopy. The results showed that the lectin pathway was activated on CC by binding of ficolin-2 and MBL in vitro, resulting in activation and deposition of complement activation products. MBL bound to CC in a calcium-dependent manner whereas ficolin-2 binding was calcium-independent. No binding was observed for ficolin-1 or ficolin-3. MBL and ficolin-2 were present in human carotid plaques, and binding of MBL to CC was confirmed in vivo by immunohistochemistry, showing localization of MBL around CC clefts. Moreover, we demonstrated that IgM, but not IgG, bound to CC in vitro and that C1q binding was facilitated by IgM. In conclusion, our study demonstrates that PRMs from the lectin pathway recognize CC and provides evidence for an important role for this pathway in the inflammatory response induced by CC in the pathophysiology of atherosclerosis.
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Christensen AN, Rydhög JS, Søndergaard RV, Andresen TL, Holm S, Munck Af Rosenschöld P, Conradsen K, Jølck RI. Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography. NANOSCALE 2016; 8:11002-11011. [PMID: 27174233 DOI: 10.1039/c6nr00201c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive (106)Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy (10- and 22 Gy) in a high-energy beam setting (18 MV). The developed silver-nanosensor provided high radiopacity on the planning CT-scans sufficient for patient positioning in image-guided radiotherapy and provided dosimetric information about the absorbed dose with a 10% and 8% standard deviation for the stereotactic regimens, 10 and 22 Gy, respectively.
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Oma I, Andersen J, Holm S, Olstad O, Fostad I, Lyberg T, Almdahl S, Molberg Ø, Hollan I. OP0282 Expression of Vitamin D Receptor Associated Genes in The Aorta of Coronary Artery Disease Patients with and without Rheumatoid Arthritis. Ann Rheum Dis 2016. [DOI: 10.1136/annrheumdis-2016-eular.3143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kilday J, Massimi L, Caldarelli M, Lee Y, Chen H, Yiang M, Parkes J, Naiker T, van Veelen M, Michiels E, Pettorini B, Mallucci C, Meijer L, Dorfer C, Czech T, Diezi M, van Schouten N, Holm S, Gustavsson B, Benesch M, Hoffman A, Muller H, Escherich G, Flitsch J, Rutkowski S, Grotzer M, Spoudeas H, Capra M, Jimenez-Guerra R, MacDonald P, Johnston D, Dvir R, Constantini S, Kuo M, Yang S, Bartels U. CR-12INTRACYSTIC INTERFERON-ALPHA IN PAEDIATRIC CRANIOPHARYNGIOMA PATIENTS: AN INTERNATIONAL MULTI-CENTRE ASSESSMENT ON BEHALF OF SIOP-E AND ISPN. Neuro Oncol 2016. [DOI: 10.1093/neuonc/now068.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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71
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Skagen K, Trøseid M, Ueland T, Holm S, Abbas A, Gregersen I, Kummen M, Bjerkeli V, Reier-Nilsen F, Russell D, Svardal A, Karlsen TH, Aukrust P, Berge RK, Hov JER, Halvorsen B, Skjelland M. The Carnitine-butyrobetaine-trimethylamine-N-oxide pathway and its association with cardiovascular mortality in patients with carotid atherosclerosis. Atherosclerosis 2016; 247:64-9. [PMID: 26868510 DOI: 10.1016/j.atherosclerosis.2016.01.033] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 12/12/2015] [Accepted: 01/20/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND AND PURPOSE γ-butyrobetaine (γBB) is a metabolite from dietary Carnitine, involved in the gut microbiota-dependent conversion from Carnitine to the pro-atherogenic metabolite trimethylamine-N-oxide (TMAO). Orally ingested γBB has a pro-atherogenic effect in experimental studies, but γBB has not been studied in relation to atherosclerosis in humans. The aim of this study was to evaluate associations between serum levels of γBB, TMAO and their common precursors Carnitine and trimethyllysine (TML) and carotid atherosclerosis and adverse outcome. METHODS Serum γBB, Carnitine, TML and TMAO were quantified by high performance liquid chromatography in patients with carotid artery atherosclerosis (n = 264) and healthy controls (n = 62). RESULTS Serum γBB (p = 0.024) and Carnitine (p = 0.001), but not TMAO or TML, were increased in patients with carotid atherosclerosis. Higher levels of γBB and TML, but not TMAO or Carnitine were independently associated with cardiovascular death also after adjustment for age and eGFR (adjusted HR [95%] 3.3 [1.9-9.1], p = 0.047 and 6.0 [1.8-20.34], p = 0.026, respectively). CONCLUSIONS Patients with carotid atherosclerosis had increased serum levels of γBB, and elevated levels of γBB and its precursor TML were associated with cardiovascular mortality. Long-term clinical studies of γBB, as a cardiovascular risk marker, and safety studies regarding dietary supplementation of γBB, are warranted.
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George AJT, Collett C, Carr AJ, Holm S, Bale C, Burton S, Campbell M, Coles A, Gottlieb G, Muir K, Parroy S, Price J, Rice ASC, Sinden J, Stephenson C, Wartolowska K, Whittall H. When should placebo surgery as a control in clinical trials be carried out? ACTA ACUST UNITED AC 2016. [DOI: 10.1308/rcsbull.2016.75] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Placebo surgery – often maligned as ‘sham surgery’ – is a tough sell to patients and to many clinicians. But could surgical research benefit from increased use of placebo control groups?
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Stavik B, Espada S, Cui XY, Iversen N, Holm S, Mowinkel MC, Halvorsen B, Skretting G, Sandset PM. EPAS1/HIF-2 alpha-mediated downregulation of tissue factor pathway inhibitor leads to a pro-thrombotic potential in endothelial cells. Biochim Biophys Acta Mol Basis Dis 2016; 1862:670-678. [PMID: 26826018 DOI: 10.1016/j.bbadis.2016.01.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 12/04/2015] [Accepted: 01/24/2016] [Indexed: 12/11/2022]
Abstract
Neovascularization and hemorrhaging are evident in advanced atherosclerotic plaques due to hypoxic conditions, and mediate the accumulation of metabolic substrates, inflammatory cells, lipids, and other blood born factors inside the plaque. Tissue factor (TF) pathway inhibitor (TFPI) is mainly expressed by endothelial cells and is the endogenous inhibitor of the coagulation activator TF, which together with the downstream product thrombin can drive plaque progression and atherogenesis. We aimed to investigate the effect of hypoxic conditions on endothelial cell expression and activity of TFPI and TF that are important in coagulation initiation. Hypoxia was induced in primary human umbilical vein endothelial cells using chemicals or 1% oxygen tension, and mRNA and protein expressions were measured using qRT-PCR, ELISA, and Western blot analysis. Microscopy of fluorescence-labeled cells was used to visualize cell-associated TFPI. Cell-surface factor Xa (FXa) activity was measured using a two-stage chromogenic substrate method. We found that hypoxia reduced the TFPI mRNA and protein levels and increased the TF mRNA expression in a dose-dependent manner. The effect on TFPI was apparent on all the protein pools of TFPI, i.e., secreted TFPI, cell-surface associated TFPI, and intracellular TFPI, and seemed to be dependent upon hypoxia inducible factor-2α (HIF-2α). An increase in FXa activity was also observed on the endothelial cell surface, reflecting an increase in pro-thrombotic potential of the cells. Our findings indicate that hypoxic conditions may enhance the pro-coagulant activity of endothelial cells, which may promote atherogenesis in addition to clinical events and thus the severity of atherosclerotic disorders.
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Zhang W, Holm S. Estimation of shear modulus in media with power law characteristics. ULTRASONICS 2016; 64:170-176. [PMID: 26385841 DOI: 10.1016/j.ultras.2015.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 04/14/2015] [Accepted: 09/02/2015] [Indexed: 06/05/2023]
Abstract
Shear wave propagation in tissue generated by the radiation force is usually modeled by either a lossless or a classical viscoelastic equation. However, experimental data shows power law behavior which is not consistent with those approaches. It is well known that fractional derivatives results in power laws, therefore a time fractional wave equation, the Caputo equation, which can be derived from the fractional Kelvin-Voigt stress and strain relation is tested. This equation is solved using the finite difference method with experimental parameters obtained from the existing literature. The equation is characterized by a fractional order which is also the power law exponent of the frequency dependent shear modulus. It is shown that for fractional order between 0 and 1, the equation gives smaller shear modulus than the classical model. The opposite situation applies for fractional order greater than 1. The numerical simulation also shows that the shear wave velocity method is only reliable for small losses. In our case, this is only for a small fractional order. Based on the published values of fractional order from other studies, there is therefore a chance for biased estimation of the shear modulus.
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Gregersen I, Holm S, Dahl TB, Halvorsen B, Aukrust P. A focus on inflammation as a major risk factor for atherosclerotic cardiovascular diseases. Expert Rev Cardiovasc Ther 2015; 14:391-403. [PMID: 26641944 DOI: 10.1586/14779072.2016.1128828] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Atherosclerosis is a dynamic, pathogenic process in the artery wall, with potential adverse outcome for the host. Acute events such as myocardial infarction and ischemic stroke often result from rupture of unstable atherosclerotic lesions. Understanding the underlying pathology of such lesions and why and when they rupture, is therefore of great interest for the development of new diagnostics and treatment. Inflammation is one of the key drivers of atherosclerotic plaque development and the interplay between inflammation and lipids constitutes the hallmark of atherosclerotic disease. This review summarizes the role of inflammation in atherosclerosis and presents some of the latest discoveries as well as unmet needs regarding the role of inflammation as major risk factor in atherosclerotic disease.
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