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Peter J. Little - One of the best experts on this subject based on the ideXlab platform.
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Methotrexate Inhibits Proliferation but not Proteoglycan Synthesis or Glycosaminoglycan Hyperelongation in Human Vascular Smooth Muscle Cells
Clinical & Experimental Pharmacology, 2015Co-Authors: Peter J. Little, Muhamad Ashraf Rostam, Robel Getachew, Danielle Kamato, Neale Cohen, Vincent Chan, Narin OsmanAbstract:Objectives: Atherosclerosis is a disease process involving the early deposition of lipids in the vessel wall trapped by modified Proteoglycans and subsequently a chronic inflammatory process leading to the clinical events. MTX has been chosen to study the potential efficacy of an anti inflammatory agent in preventing atherosclerosis and secondary cardiovascular disease in the cardiovascular inflammation reduction trial (CIRT). Methods: We have investigated cell proliferation and growth factor stimulated Proteoglycan Synthesis in vascular smooth muscle (VSMC) to assess some of the direct effects of MTX. Experiments were conducted in cultured human VSMC. Proliferation was assessed by the gold standard technique of cell counting and Proteoglycan Synthesis by 35S radiosulafate incorporation and size analysis by SDS PAGE. Key findings: MTX had a concentration-dependent inhibitory effect on serum stimulated VSMC proliferation with a maximum and total inhibitory effect at 10 μM. Thrombin, platelet-derived growth factor and transforming growth factor beta stimulated Proteoglycan Synthesis and increased the size of the biglycan molecules but MTX (10 μM) had no effect on any of these responses. Conclusions: The outcome of a trial with MTX will reflect the potential of targeting inflammation for the prevention of atherosclerosis and it remains an interesting proposition to evaluate the effects of a "Proteoglycan inhibitor" on atherosclerosis.
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Suramin inhibits PDGF-stimulated receptor phosphorylation, Proteoglycan Synthesis and glycosaminoglycan hyperelongation in human vascular smooth muscle cells
The Journal of pharmacy and pharmacology, 2013Co-Authors: Peter J. Little, Muhamad Ashraf Rostam, Terrence J. Piva, Robel Getachew, Danielle Kamato, Daniel Guidone, Mandy L. Ballinger, Wenhua Zheng, Narin OsmanAbstract:Objectives: Suramin is a polysulfonated naphthylurea with antiparasitic and potential antineoplastic activity. Suramin's pharmacological actions, which have not yet been fully elucidated, include antagonism of the action of platelet-derived growth factor (PDGF) at its receptor. We investigated the effects of suramin on PDGF-stimulated Proteoglycan Synthesis. Methods: Human vascular smooth muscle cells (VSMCs) were incubated in the presence and absence of PDGF and suramin with [H]thymidine or SO as radiolabels. Mitogenic response was determined by [H]thymidine incorporation. PDGFβ receptor phosphorylation was assessed by western blotting. Proteoglycan size and glycosaminoglycan chain Synthesis and size were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Alphascreen phosphotyrosine assay kit was used to investigate PDGFβ receptor tyrosine kinase inhibition by suramin. Key findings: Suramin decreased PDGF-stimulated proliferation, Proteoglycan Synthesis and GAG chain hyperelongation. Suramin also directly inhibited PDGFβ receptor kinase activity as well as PDGFβ receptor phosphorylation in intact VSMCs. Conclusions: These data show that inhibition of PDGFβ receptor phosphorylation in intact cells is necessary to define a fully active PDGF antagonist. They also confirm that PDGFβ receptor kinase activity is necessary for PDGF-mediated atherogenic changes in Proteoglycan Synthesis and support efforts to develop PDGFβ receptor antagonists as potential anti-atherosclerotic agents.
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p38 MAP kinase mediated Proteoglycan Synthesis as a target for the prevention of atherosclerosis.
Cardiovascular & hematological disorders drug targets, 2008Co-Authors: Narin Osman, Robel Getachew, Mandy L. Ballinger, Harsha Dadlani, Micah L Burch, Peter J. LittleAbstract:The major underlying pathology of most cardiovascular disease is the chronic inflammatory disease of atherosclerosis. Type 2 diabetes, also recognised as an inflammatory condition, accelerates the development of atherosclerosis. Current therapies for atherosclerosis target risk factors such as elevated blood lipids and hypertension and are of strong but limited efficacy. The “response to retention” hypothesis states that atherosclerosis is initiated by the accumulation of lipids through binding to extracellular matrix, and this is specifically the glycosaminoglycan (GAG) chains on Proteoglycans. Many vasoactive agonists stimulate changes in the structure of the GAGs which increase lipid binding and the relevant signalling pathways are a potential therapeutic target. It has recently been demonstrated that the actions of transforming growth factor β on vascular smooth muscle Proteoglycan Synthesis involves signalling through p38 MAP kinase and inhibition of this pathway reduces binding of lipids. Inhibition of p38 MAP kinase will elicit a wide spread antiinflammatory response which may alleviate some of the deleterious processes in cardiovascular tissues. This article explores the potential for the actions of p38 MAP kinase inhibitors directed at Proteoglycan Synthesis in vascular smooth muscle to contribute to the beneficial outcomes from targeting p38 MAP kinase for the prevention of cardiovascular disease.
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Smad and p38 MAP kinase-mediated signaling of Proteoglycan Synthesis in vascular smooth muscle
The Journal of biological chemistry, 2008Co-Authors: Harsha Dadlani, Mandy L. Ballinger, Robel Getachew, Narin Osman, Peter J. LittleAbstract:Atherosclerosis is the underlying pathological process of most cardiovascular disease. A critical component of the "response to retention" hypothesis of atherogenesis is Proteoglycan/low density lipoprotein (LDL) binding. Transforming growth factor beta (TGF-beta) is present in atherosclerotic lesions, regulates vascular smooth muscle cell (VSMC) Proteoglycan Synthesis via an unknown signaling pathway, and increases Proteoglycan/LDL binding. This pathway was investigated using the activin receptor-like kinase 5 (ALK5) inhibitor SB431542 and inhibitors of p38 MAP kinase as a possible downstream or alternative mediator. TGF-beta stimulated and SB431542 inhibited the phosphorylation of Smad2/3. In human VSMC, TGF-beta increased [(35)S]sulfate incorporation into Proteoglycans associated with a 19% increase in glycosaminoglycan (GAG) chain size by size exclusion chromatography. SB431542 caused a concentration-dependent decrease in TGF-beta-mediated [(35)S]sulfate incorporation with 92% inhibition at 3 mum. Two different p38 MAP kinase inhibitors, SB203580 and SB202190, but not the inactive analogue SB202474, concentration-dependently blocked TGF-beta-mediated [(35)S]sulfate incorporation. TGF-beta increased [(3)H]glucosamine incorporation into glycosaminoglycans by 180% and [(35)S]Met/Cys incorporation into Proteoglycan core proteins by 35% with both effects completely inhibited by SB431542. Blocking both Smad2/3 and p38 MAP kinase pathways prevented the effect of TGF-beta to increase Proteoglycan to LDL binding. TGF-beta mediates its effects on Proteoglycan Synthesis in VSMCs via the ALK5/Smad2/3 phosphorylation pathway as well as via the p38 MAP kinase signaling cascade. Further studies of downstream pathways controlling Proteoglycan Synthesis may identify potential therapeutic targets for the prevention of atherosclerosis and cardiovascular disease.
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Phosphorylated Troglitazone Activates PPARγ and Inhibits Vascular Smooth Muscle Cell Proliferation and Proteoglycan Synthesis
Journal of cardiovascular pharmacology, 2008Co-Authors: Peter J. Little, Mandy L. Ballinger, Narin Osman, Soniya Survase, Esra Ogru, Stephen Lindsay Geytenbeek, Dennis Bruemmer, Julie NigroAbstract:Phosphorylation of alpha-tocopherol produces an entity with enhanced antiatherogenic properties. Troglitazone, an alpha-tocopherol derivative of a 2,4-thiazolidinedione nucleus, is an antidiabetic agent that shows fatal idiosyncratic hepatotoxicity, a property not shared by later agents. We investigated the effects of phosphorylation of troglitazone (to yield "phosphoglitazone") on the biochemical pharmacologic properties of troglitazone. We investigated its ability to act as a PPARgamma agonist and to inhibit 2 atherogenic properties of vascular smooth muscle cells (vSMC)-proliferation and Proteoglycan Synthesis. PPARgamma activity was assessed in a transfection assay. Proliferation was assessed by [H]-thymidine incorporation and cell counting and Proteoglycan Synthesis by [S]-sulfate incorporation using human vSMCs stimulated with platelet-derived growth factor (PDGF; 50 ng/mL) and transforming growth factor (TGF)-beta (2 ng/mL). Phosphoglitazone was a full agonist for PPARgamma with a potency and efficacy similar to troglitazone. Phosphoglitazone also inhibited cell proliferation and Proteoglycan Synthesis with potency similar to troglitazone. We conclude that phosphorylation retains the pharmacologic activity of troglitazone while decreasing its lipophilicity and therefore potentially its toxicity. A phosphorylated derivative of a 2,4-thiazolidinedione warrants further investigation as a potential new therapeutic agent for the treatment of insulin resistance and Type 2 diabetes.
Narin Osman - One of the best experts on this subject based on the ideXlab platform.
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Methotrexate Inhibits Proliferation but not Proteoglycan Synthesis or Glycosaminoglycan Hyperelongation in Human Vascular Smooth Muscle Cells
Clinical & Experimental Pharmacology, 2015Co-Authors: Peter J. Little, Muhamad Ashraf Rostam, Robel Getachew, Danielle Kamato, Neale Cohen, Vincent Chan, Narin OsmanAbstract:Objectives: Atherosclerosis is a disease process involving the early deposition of lipids in the vessel wall trapped by modified Proteoglycans and subsequently a chronic inflammatory process leading to the clinical events. MTX has been chosen to study the potential efficacy of an anti inflammatory agent in preventing atherosclerosis and secondary cardiovascular disease in the cardiovascular inflammation reduction trial (CIRT). Methods: We have investigated cell proliferation and growth factor stimulated Proteoglycan Synthesis in vascular smooth muscle (VSMC) to assess some of the direct effects of MTX. Experiments were conducted in cultured human VSMC. Proliferation was assessed by the gold standard technique of cell counting and Proteoglycan Synthesis by 35S radiosulafate incorporation and size analysis by SDS PAGE. Key findings: MTX had a concentration-dependent inhibitory effect on serum stimulated VSMC proliferation with a maximum and total inhibitory effect at 10 μM. Thrombin, platelet-derived growth factor and transforming growth factor beta stimulated Proteoglycan Synthesis and increased the size of the biglycan molecules but MTX (10 μM) had no effect on any of these responses. Conclusions: The outcome of a trial with MTX will reflect the potential of targeting inflammation for the prevention of atherosclerosis and it remains an interesting proposition to evaluate the effects of a "Proteoglycan inhibitor" on atherosclerosis.
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Suramin inhibits PDGF-stimulated receptor phosphorylation, Proteoglycan Synthesis and glycosaminoglycan hyperelongation in human vascular smooth muscle cells
The Journal of pharmacy and pharmacology, 2013Co-Authors: Peter J. Little, Muhamad Ashraf Rostam, Terrence J. Piva, Robel Getachew, Danielle Kamato, Daniel Guidone, Mandy L. Ballinger, Wenhua Zheng, Narin OsmanAbstract:Objectives: Suramin is a polysulfonated naphthylurea with antiparasitic and potential antineoplastic activity. Suramin's pharmacological actions, which have not yet been fully elucidated, include antagonism of the action of platelet-derived growth factor (PDGF) at its receptor. We investigated the effects of suramin on PDGF-stimulated Proteoglycan Synthesis. Methods: Human vascular smooth muscle cells (VSMCs) were incubated in the presence and absence of PDGF and suramin with [H]thymidine or SO as radiolabels. Mitogenic response was determined by [H]thymidine incorporation. PDGFβ receptor phosphorylation was assessed by western blotting. Proteoglycan size and glycosaminoglycan chain Synthesis and size were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Alphascreen phosphotyrosine assay kit was used to investigate PDGFβ receptor tyrosine kinase inhibition by suramin. Key findings: Suramin decreased PDGF-stimulated proliferation, Proteoglycan Synthesis and GAG chain hyperelongation. Suramin also directly inhibited PDGFβ receptor kinase activity as well as PDGFβ receptor phosphorylation in intact VSMCs. Conclusions: These data show that inhibition of PDGFβ receptor phosphorylation in intact cells is necessary to define a fully active PDGF antagonist. They also confirm that PDGFβ receptor kinase activity is necessary for PDGF-mediated atherogenic changes in Proteoglycan Synthesis and support efforts to develop PDGFβ receptor antagonists as potential anti-atherosclerotic agents.
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p38 MAP kinase mediated Proteoglycan Synthesis as a target for the prevention of atherosclerosis.
Cardiovascular & hematological disorders drug targets, 2008Co-Authors: Narin Osman, Robel Getachew, Mandy L. Ballinger, Harsha Dadlani, Micah L Burch, Peter J. LittleAbstract:The major underlying pathology of most cardiovascular disease is the chronic inflammatory disease of atherosclerosis. Type 2 diabetes, also recognised as an inflammatory condition, accelerates the development of atherosclerosis. Current therapies for atherosclerosis target risk factors such as elevated blood lipids and hypertension and are of strong but limited efficacy. The “response to retention” hypothesis states that atherosclerosis is initiated by the accumulation of lipids through binding to extracellular matrix, and this is specifically the glycosaminoglycan (GAG) chains on Proteoglycans. Many vasoactive agonists stimulate changes in the structure of the GAGs which increase lipid binding and the relevant signalling pathways are a potential therapeutic target. It has recently been demonstrated that the actions of transforming growth factor β on vascular smooth muscle Proteoglycan Synthesis involves signalling through p38 MAP kinase and inhibition of this pathway reduces binding of lipids. Inhibition of p38 MAP kinase will elicit a wide spread antiinflammatory response which may alleviate some of the deleterious processes in cardiovascular tissues. This article explores the potential for the actions of p38 MAP kinase inhibitors directed at Proteoglycan Synthesis in vascular smooth muscle to contribute to the beneficial outcomes from targeting p38 MAP kinase for the prevention of cardiovascular disease.
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Smad and p38 MAP kinase-mediated signaling of Proteoglycan Synthesis in vascular smooth muscle
The Journal of biological chemistry, 2008Co-Authors: Harsha Dadlani, Mandy L. Ballinger, Robel Getachew, Narin Osman, Peter J. LittleAbstract:Atherosclerosis is the underlying pathological process of most cardiovascular disease. A critical component of the "response to retention" hypothesis of atherogenesis is Proteoglycan/low density lipoprotein (LDL) binding. Transforming growth factor beta (TGF-beta) is present in atherosclerotic lesions, regulates vascular smooth muscle cell (VSMC) Proteoglycan Synthesis via an unknown signaling pathway, and increases Proteoglycan/LDL binding. This pathway was investigated using the activin receptor-like kinase 5 (ALK5) inhibitor SB431542 and inhibitors of p38 MAP kinase as a possible downstream or alternative mediator. TGF-beta stimulated and SB431542 inhibited the phosphorylation of Smad2/3. In human VSMC, TGF-beta increased [(35)S]sulfate incorporation into Proteoglycans associated with a 19% increase in glycosaminoglycan (GAG) chain size by size exclusion chromatography. SB431542 caused a concentration-dependent decrease in TGF-beta-mediated [(35)S]sulfate incorporation with 92% inhibition at 3 mum. Two different p38 MAP kinase inhibitors, SB203580 and SB202190, but not the inactive analogue SB202474, concentration-dependently blocked TGF-beta-mediated [(35)S]sulfate incorporation. TGF-beta increased [(3)H]glucosamine incorporation into glycosaminoglycans by 180% and [(35)S]Met/Cys incorporation into Proteoglycan core proteins by 35% with both effects completely inhibited by SB431542. Blocking both Smad2/3 and p38 MAP kinase pathways prevented the effect of TGF-beta to increase Proteoglycan to LDL binding. TGF-beta mediates its effects on Proteoglycan Synthesis in VSMCs via the ALK5/Smad2/3 phosphorylation pathway as well as via the p38 MAP kinase signaling cascade. Further studies of downstream pathways controlling Proteoglycan Synthesis may identify potential therapeutic targets for the prevention of atherosclerosis and cardiovascular disease.
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Phosphorylated Troglitazone Activates PPARγ and Inhibits Vascular Smooth Muscle Cell Proliferation and Proteoglycan Synthesis
Journal of cardiovascular pharmacology, 2008Co-Authors: Peter J. Little, Mandy L. Ballinger, Narin Osman, Soniya Survase, Esra Ogru, Stephen Lindsay Geytenbeek, Dennis Bruemmer, Julie NigroAbstract:Phosphorylation of alpha-tocopherol produces an entity with enhanced antiatherogenic properties. Troglitazone, an alpha-tocopherol derivative of a 2,4-thiazolidinedione nucleus, is an antidiabetic agent that shows fatal idiosyncratic hepatotoxicity, a property not shared by later agents. We investigated the effects of phosphorylation of troglitazone (to yield "phosphoglitazone") on the biochemical pharmacologic properties of troglitazone. We investigated its ability to act as a PPARgamma agonist and to inhibit 2 atherogenic properties of vascular smooth muscle cells (vSMC)-proliferation and Proteoglycan Synthesis. PPARgamma activity was assessed in a transfection assay. Proliferation was assessed by [H]-thymidine incorporation and cell counting and Proteoglycan Synthesis by [S]-sulfate incorporation using human vSMCs stimulated with platelet-derived growth factor (PDGF; 50 ng/mL) and transforming growth factor (TGF)-beta (2 ng/mL). Phosphoglitazone was a full agonist for PPARgamma with a potency and efficacy similar to troglitazone. Phosphoglitazone also inhibited cell proliferation and Proteoglycan Synthesis with potency similar to troglitazone. We conclude that phosphorylation retains the pharmacologic activity of troglitazone while decreasing its lipophilicity and therefore potentially its toxicity. A phosphorylated derivative of a 2,4-thiazolidinedione warrants further investigation as a potential new therapeutic agent for the treatment of insulin resistance and Type 2 diabetes.
W.b. Van Den Berg - One of the best experts on this subject based on the ideXlab platform.
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EFFECT OF INTERLEUKIN 1 AND LEUKAEMIA INHIBITORY FACTOR ON CHONDROCYTE METABOLISM IN ARTICULAR CARTILAGE FROM NORMAL AND INTERLEUKIN-6-DEFICIENT MICE: ROLE OF NITRIC OXIDE AND IL-6 IN THE SUPPRESSION OF Proteoglycan Synthesis
Cytokine, 1997Co-Authors: F.a.j. Van De Loo, Onno J. Arntz, W.b. Van Den BergAbstract:We studied the role of IL-6 and nitric oxide (NO) in IL-1 and leukaemia inhibitory factor (LIF) induced suppression of Proteoglycan Synthesis. Cartilage explants of patellae and femoral heads were incubated with IL-1 or LIF. Conditioned media were analysed for IL-6 activity (B9-assay) and NO content (Griess). Proteoglycan Synthesis was assessed using pSJsulfate incorporation. IL-1 dose dependency induced IL-6 Synthesis and neutralizing IL-6 with antibodies did not reduce Proteoglycan Synthesis suppression, neither in expiants nor in isolated chondrocytes. IL-6 independence was confirmed using cartilage from IL-6 deficient mice. IL-1 significantly increased NO release in normal and IL-6 deficient chondrocytes and addition of the NO synthase inhibitor, N^-monomethyl-L-arginine markedly alleviated Proteoglycan Synthesis suppression. LIF also induced Proteoglycan Synthesis suppression in cartilage from normal and IL-6 deficient mice, but the suppression was neither accompanied by nor dependent on NO release. Furthermore, Proteoglycan Synthesis suppression during experimental arthritis was similar in both normal and IL-6 deficient mice. We concluded that IL-6 is not a necessary cofactor in IL-1 and LIF induced suppression of Proteoglycan Synthesis. Furthermore, only the IL-1 induced suppression was mediated by NO, suggesting that inhibition of Proteoglycan Synthesis may occur through different pathways. ( 1997 Academic Press Limited Cytokines are im portant mediators in the patho genesis o f rheumatoid arthritis (R A )1'" and are produced in the inflamed joint.1 4 It has been claimed that T N F -a is driving most of the IL-1 production in the inflamed synovia of RA patients5 suggesting a hierarchy in the dynamic interaction of cytokines. The cascade of T N F IL-1 L IF — > IL-6 was to be involved in the pathogenesis of RA.6 T N F -a and IL-1 share many of their activities,7 and the therapeutic intervention of RA is recently directed towards antagonizing and modifying
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Stimulation of Proteoglycan Synthesis by triamcinolone acetonide and insulin-like growth factor 1 in normal and arthritic murine articular cartilage.
The Journal of rheumatology, 1994Co-Authors: P. J. Verschure, P.m. Van Der Kraan, Elly L. Vitters, W.b. Van Den BergAbstract:OBJECTIVE During experimentally induced arthritis, inhibition of Proteoglycan Synthesis is one of the mechanisms leading to cartilage destruction. Disturbed anabolic signalling might contribute to this impaired chondrocyte Proteoglycan Synthesis. We investigated the effects of insulin-like growth factor 1 (IGF-1) and the glucocorticoid, triamcinolone acetonide, on in vitro chondrocyte Proteoglycan Synthesis of articular cartilage obtained from normal and arthritic mouse knee joints. METHODS Proteoglycan Synthesis was measured by 35S sulfate incorporation and the hydrodynamic volume of newly synthesized Proteoglycans was analyzed with gel chromatography. RESULTS Culturing normal cartilage with IGF-1 resulted in significant enhancement of chondrocyte Proteoglycan Synthesis. Concerning the hydrodynamic volume of newly synthesized Proteoglycans after culture with IGF-1, Proteoglycan monomers with large hydrodynamic size, similar to those synthesized immediately after dissection were observed. In arthritic cartilage, IGF-1 failed to stimulate Proteoglycan Synthesis and only Proteoglycans with relatively small dimensions were produced. However, in the presence of the steroid triamcinolone acetonide, Synthesis of hydrodynamically large Proteoglycans were found in arthritic as well as normal cartilage. CONCLUSION Our observations indicate that steroids may play a critical role in maintaining cartilage integrity in both normal and arthritic cartilage.
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Inhibition of Proteoglycan Synthesis by transforming growth factor beta in anatomically intact articular cartilage of murine patellae.
Annals of the rheumatic diseases, 1992Co-Authors: P.m. Van Der Kraan, Elly L. Vitters, W.b. Van Den BergAbstract:The effect of transforming growth factor beta (TGF beta) on Proteoglycan Synthesis and degradation in anatomically intact articular cartilage of murine patellae was studied. Exogenously added TGF beta up to a concentration of 200 pmol/l had no effect on Proteoglycan Synthesis in intact articular cartilage. Neutralisation of endogenously produced TGF beta with a specific monoclonal antibody to TGF beta, however, led to stimulation of Proteoglycan Synthesis, indicating that TGF beta itself inhibits Proteoglycan Synthesis in anatomically intact cartilage. Transforming growth factor beta decreased the degradation of Proteoglycans in intact cartilage in the absence of fetal calf serum or insulin-like growth factor 1. In the presence of fetal calf serum or insulin-like growth factor 1, TGF beta had no additional effect on Proteoglycan breakdown.
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Local changes in Proteoglycan Synthesis during culture are different for normal and osteoarthritic cartilage.
The American journal of pathology, 1992Co-Authors: F.p.j.g. Lafeber, P.m. Van Der Kraan, Elly L. Vitters, W.b. Van Den Berg, H L Van Roy, O. Huber-bruning, J. W. J. BijlsmaAbstract:Proteoglycan Synthesis of mild-to-moderate osteoarthritic human knee cartilage was compared with that of normal cartilage of the same donor. Immediately after cartilage was obtained, the Synthesis rate of Proteoglycans was higher for osteoarthritic cartilage than for normal cartilage. Proteoglycan Synthesis was then located, for both normal and osteoarthritic cartilage, in the middle and deep zone. However, after 4 days of culture, Proteoglycan Synthesis rate was higher for normal cartilage than for osteoarthritic cartilage. The reason for this transition from a lower to a higher Proteoglycan Synthesis rate was a strong increase in the Proteoglycan Synthesis in the superficial zone of normal cartilage. This was not observed for the osteoarthritic cartilage. The chondrocytes in the superficial zone of osteoarthritic cartilage, in contrast to normal cartilage, were mainly joined in cell clusters and proliferating. This may explain their inability to contribute to Proteoglycan Synthesis.
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Protection against cartilage Proteoglycan Synthesis inhibition by antiinterleukin 1 antibodies in experimental arthritis.
The Journal of rheumatology, 1992Co-Authors: F.a.j. Van De Loo, Onno J. Arntz, Ivan G. Otterness, W.b. Van Den BergAbstract:We have used neutralizing antibodies raised against murine recombinant interleukin 1 (IL-1) to demonstrate a role for IL-1 in the cartilage destruction and inflammation of antigen induced arthritis. Ex vivo production of IL-1 was demonstrated in tissue cultures of joint cross sections shortly after arthritis induction. Neutralizing antimurine IL-1 antibodies identified the activity to be about 80% IL-1 alpha 24 h after onset of arthritis. In animals receiving a single injection of anti-IL-1 antisera at Day -3, cartilage Proteoglycan Synthesis suppression during the first 2 days of arthritis was prevented. Normal Proteoglycan Synthesis was maintained until Day 4 when anti-IL-1 antisera was given at Days -2, 0, and 2 or arthritis. Dose response experiments showed that the reduction in inflammation was insufficient to account for the clearcut reduction in cartilage Proteoglycan Synthesis inhibition. Our results demonstrate that IL-1 plays a role in cartilage pathology in murine antigen induced arthritis.
Jody A. Summers Rada - One of the best experts on this subject based on the ideXlab platform.
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Regulation of the biphasic decline in scleral Proteoglycan Synthesis during the recovery from induced myopia
Experimental eye research, 2011Co-Authors: Jody A. Summers Rada, Lindsey R. HollawayAbstract:Abstract During the recovery from form deprivation myopia (myopic defocus), the rate of Proteoglycan Synthesis in the posterior sclera decreases co-incident with a deceleration of axial elongation. The choroid has been implicated in the regulation of scleral Proteoglycan Synthesis, possibly through the Synthesis and secretion of scleral growth inhibitors. Therefore these studies were carried out to attempt to establish a causal relationship between choroidal secretion and the inhibition of scleral Proteoglycan Synthesis during the recovery from induced myopia. Chicks were form vision deprived for 10 days followed by a recovery period (3 h–20 days) of unrestricted vision. Sclera and choroids (5 mm punches) were isolated from control and treated eyes. The rate of Proteoglycan Synthesis was estimated by the incorporation of 35c in cetylpyridinium chloride-precipitable glycosaminoglycans by isolated sclera of control and treated eyes. Additionally, choroids from control and treated eyes were placed in co-culture with untreated age-matched normal chick sclera for 20–24 h, after which time sclera were removed and scleral Proteoglycan Synthesis rates were determined. Following removal of occluders, a biphasic decline was observed in scleral Proteoglycan Synthesis: A rapid decline in Proteoglycan Synthesis (−7.6% per hr; r2 = 0.923) was observed over the first 12 h of recovery, followed by a slow decline extending from 12 to 96 h (−0.3% per hr; r2 = 0.735). Proteoglycan Synthesis rates gradually increased to control levels over the next 96 h at a rate of +0.3% per hr. No relative Proteoglycan inhibition was observed when untreated sclera were co-cultured with choroids from eyes recovering for 0–4 days, whereas co-culture of untreated sclera with choroids from eyes recovering for 5 and 8 days resulted in significant inhibition of sclera Proteoglycan Synthesis, relative to that of sclera co-cultured with choroids from control eyes (≈−24%, P
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Inhibition of scleral Proteoglycan Synthesis blocks deprivation-induced axial elongation in chicks.
Experimental eye research, 2002Co-Authors: Jody A. Summers Rada, Janell M. Johnson, Virginia R. Achen, Kevin G. RadaAbstract:Abstract A specific inhibitor of Proteoglycan Synthesis was administered to chicks undergoing the development of form deprivation myopia in order to test the hypothesis that increases in Proteoglycan Synthesis are responsible for normal and/or deprivation-induced ocular elongation in chicks. Chicks undergoing monocular form deprivation were treated with p -nitrophenyl-β- D -xylopyranoside (β-xyloside) via i.p. injection every 8 hr for 5–11 days. Ocular measurements were made at the end of the experiment using high frequency A-scan ultrasound in conjunction with a LabView (v. 5.0) analysis program. Following ultrasound measurements, sclera were isolated and Proteoglycans characterized by Sepharose CL-2B and Western blot analyses. Preliminary studies indicated that i.p. administration of β-xyloside maximally inhibited sulfate incorporation into Proteoglycans 8 hr after administration. β-Xyloside treatment resulted in a significant reduction in the axial length, vitreous chamber depth, and rate of axial elongation of form deprived eyes as compared with form deprived eyes from vehicle treated chicks (P
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Decreased Proteoglycan Synthesis associated with form deprivation myopia in mature primate eyes.
Investigative Ophthalmology & Visual Science, 2000Co-Authors: Jody A. Summers Rada, Debora L. Nickla, David TroiloAbstract:PURPOSE. The rate of Proteoglycan Synthesis was measured in the scleras of adolescent marmosets that had undergone monocular form deprivation to characterize the scleral extracellular matrix changes associated with the development of myopia in a mature primate. METHODS. Form deprivation myopia was induced in adolescent marmosets by unilateral lid suture for an average of 108 days. After the lids were reopened, the axial lengths and refractions were measured at intervals for up to 39 weeks. At the end of the study period, sclera were isolated and immediately radiolabeled with 35 SO4 in organ culture. Proteoglycan Synthesis rates were determined by measurement of 35 SO4 incorporation into cetylpyridinium chloride‐precipitable glycosaminoglycans after digestion of the scleral samples with proteinase K. Collagen content was determined by measurement of total hydroxyproline in scleral digests. Newly synthesized Proteoglycans were separated on a Sepharose CL-4B molecular sieve column and identified by their core proteins by Western blot analyses. RESULTS. Lid suture resulted in myopia due to a significant increase in vitreous chamber depth. After Sepharose CL-4B chromatography, newly synthesized scleral Proteoglycans isolated from normal, form-deprived, and contralateral control eyes, resolved into one major peak that eluted in the position of decorin, a small chondroitin-dermatan sulfate Proteoglycan. After digestion of the major peak with chondroitinase ABC, an approximately 45-kDa core protein was detected by Western blot analyses, confirming the presence of decorin. Form deprivation resulted in a significant reduction in the rate of Proteoglycan Synthesis in the posterior sclera (243.55%, P # 0.001). Proteoglycan Synthesis was also significantly reduced in the posterior sclera of form-deprived eyes relative to total collagen content (236.19%, P # 0.01) and was negatively correlated with the rate of vitreous chamber elongation in the deprived eye (r 2 5 0.779, P # 0.05). CONCLUSIONS. Significant extracellular matrix remodeling occurs in the posterior sclera of the adolescent primate eye during vitreous chamber elongation and myopia development. The negative correlation between vitreous chamber elongation rates and the Synthesis rates of decorin in form-deprived eyes suggests that Proteoglycan Synthesis within the posterior sclera plays a role in the regulation of ocular size and refraction in the adolescent marmoset. (Invest Ophthalmol Vis Sci. 2000;41:2050 ‐2058)
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Regional Proteoglycan Synthesis in the Sclera of Experimentally Myopic Chicks
Experimental eye research, 1994Co-Authors: Jody A. Summers Rada, Amy L. Matthews, Holly BrenzaAbstract:Abstract Proteoglycan distribution and Synthesis were compared in the sclera of normal and 10-day-form-vision-deprived (myopic) chick eyes using immnnocytochemical, biochemical and autoradiographic techniques. Immunostaining with specific antibodies indicated that decorin is present in both the fibrous and cartilaginous layers of chick sclera, while aggrecan localizes only to the cartilaginous layer. For biochemical analyses of Proteoglycan Synthesis, sclera were isolated from control and 10-day-form-vision-deprived eyes and radiolabeled in organ culture with 35SO4. Proteoglycan Synthesis was significantly increased only within a 6·5-mm-diameter button from the posterior pole of deprived eyes (+ 113%, P = 0·04), while no significant differences were detected in anterior and equatorial regions of control and deprived eyes. Chromatographic analyses of newly synthesized Proteoglycans indicated that form-deprivation stimulates the Synthesis of a large chondroitin/keratan sulfate Proteoglycan (+ 77·47%), eluting at the position of aggrecan, as well as smaller chondroitin sulfate and keratan sulfate Proteoglycans (+91·05%), which coelute with decorin. Autoradiographic analysis of incorporated sulfate indicated that the increase in Proteoglycan Synthesis observed in the posterior pole of deprived eyes occurs only in the cartilaginous scleral layer. The distributio n of incorporated 35SO4, present over the cartilaginous layer of deprived sclera indicates that Proteoglycan Synthesis is lowest in scleral cartilage adjacent to the choroid and higher in interstitial regions of posterior cartilaginous sclera as well as in regions near the outer fibrous perichondrium. These results suggest that form-deprivation induced scleral growth in chicks can be attributed to growth and differentiation of scleral cartilage in the posterior pole.
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Proteoglycan Synthesis by scleral chondrocytes is modulated by a vision dependent mechanism.
Current eye research, 1992Co-Authors: Jody A. Summers Rada, Amy L. Mcfarland, Pamela K. Cornuet, John R. HassellAbstract:Proteoglycan Synthesis was measured in chick sclera at the onset of form-deprivation myopia, as well as in the period immediately following removal of the occluder. Two day-old chicks were monocularly form vision deprived for periods from one to ten days and Proteoglycan Synthesis was determined after placing posterior scleral buttons in organ culture and measuring 35SO4 incorporation into glycosaminoglycans. Following 24 hrs of form-deprivation, Proteoglycan Synthesis was 33% higher in myopic eyes as compared with paired control eyes. The rate of Proteoglycan Synthesis further increased to levels 83% higher than controls after four days of form-deprivation and remained elevated throughout the ten day period of deprivation. Removal of the occluder after 10 days of form-deprivation resulted in a rapid drop in the rate of Proteoglycan Synthesis to control levels within 24 hrs. Proteoglycan Synthesis was also measured in scleral chondrocytes isolated from control and myopic eyes after 10 days of form-depriva...
Robel Getachew - One of the best experts on this subject based on the ideXlab platform.
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Methotrexate Inhibits Proliferation but not Proteoglycan Synthesis or Glycosaminoglycan Hyperelongation in Human Vascular Smooth Muscle Cells
Clinical & Experimental Pharmacology, 2015Co-Authors: Peter J. Little, Muhamad Ashraf Rostam, Robel Getachew, Danielle Kamato, Neale Cohen, Vincent Chan, Narin OsmanAbstract:Objectives: Atherosclerosis is a disease process involving the early deposition of lipids in the vessel wall trapped by modified Proteoglycans and subsequently a chronic inflammatory process leading to the clinical events. MTX has been chosen to study the potential efficacy of an anti inflammatory agent in preventing atherosclerosis and secondary cardiovascular disease in the cardiovascular inflammation reduction trial (CIRT). Methods: We have investigated cell proliferation and growth factor stimulated Proteoglycan Synthesis in vascular smooth muscle (VSMC) to assess some of the direct effects of MTX. Experiments were conducted in cultured human VSMC. Proliferation was assessed by the gold standard technique of cell counting and Proteoglycan Synthesis by 35S radiosulafate incorporation and size analysis by SDS PAGE. Key findings: MTX had a concentration-dependent inhibitory effect on serum stimulated VSMC proliferation with a maximum and total inhibitory effect at 10 μM. Thrombin, platelet-derived growth factor and transforming growth factor beta stimulated Proteoglycan Synthesis and increased the size of the biglycan molecules but MTX (10 μM) had no effect on any of these responses. Conclusions: The outcome of a trial with MTX will reflect the potential of targeting inflammation for the prevention of atherosclerosis and it remains an interesting proposition to evaluate the effects of a "Proteoglycan inhibitor" on atherosclerosis.
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Suramin inhibits PDGF-stimulated receptor phosphorylation, Proteoglycan Synthesis and glycosaminoglycan hyperelongation in human vascular smooth muscle cells
The Journal of pharmacy and pharmacology, 2013Co-Authors: Peter J. Little, Muhamad Ashraf Rostam, Terrence J. Piva, Robel Getachew, Danielle Kamato, Daniel Guidone, Mandy L. Ballinger, Wenhua Zheng, Narin OsmanAbstract:Objectives: Suramin is a polysulfonated naphthylurea with antiparasitic and potential antineoplastic activity. Suramin's pharmacological actions, which have not yet been fully elucidated, include antagonism of the action of platelet-derived growth factor (PDGF) at its receptor. We investigated the effects of suramin on PDGF-stimulated Proteoglycan Synthesis. Methods: Human vascular smooth muscle cells (VSMCs) were incubated in the presence and absence of PDGF and suramin with [H]thymidine or SO as radiolabels. Mitogenic response was determined by [H]thymidine incorporation. PDGFβ receptor phosphorylation was assessed by western blotting. Proteoglycan size and glycosaminoglycan chain Synthesis and size were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Alphascreen phosphotyrosine assay kit was used to investigate PDGFβ receptor tyrosine kinase inhibition by suramin. Key findings: Suramin decreased PDGF-stimulated proliferation, Proteoglycan Synthesis and GAG chain hyperelongation. Suramin also directly inhibited PDGFβ receptor kinase activity as well as PDGFβ receptor phosphorylation in intact VSMCs. Conclusions: These data show that inhibition of PDGFβ receptor phosphorylation in intact cells is necessary to define a fully active PDGF antagonist. They also confirm that PDGFβ receptor kinase activity is necessary for PDGF-mediated atherogenic changes in Proteoglycan Synthesis and support efforts to develop PDGFβ receptor antagonists as potential anti-atherosclerotic agents.
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p38 MAP kinase mediated Proteoglycan Synthesis as a target for the prevention of atherosclerosis.
Cardiovascular & hematological disorders drug targets, 2008Co-Authors: Narin Osman, Robel Getachew, Mandy L. Ballinger, Harsha Dadlani, Micah L Burch, Peter J. LittleAbstract:The major underlying pathology of most cardiovascular disease is the chronic inflammatory disease of atherosclerosis. Type 2 diabetes, also recognised as an inflammatory condition, accelerates the development of atherosclerosis. Current therapies for atherosclerosis target risk factors such as elevated blood lipids and hypertension and are of strong but limited efficacy. The “response to retention” hypothesis states that atherosclerosis is initiated by the accumulation of lipids through binding to extracellular matrix, and this is specifically the glycosaminoglycan (GAG) chains on Proteoglycans. Many vasoactive agonists stimulate changes in the structure of the GAGs which increase lipid binding and the relevant signalling pathways are a potential therapeutic target. It has recently been demonstrated that the actions of transforming growth factor β on vascular smooth muscle Proteoglycan Synthesis involves signalling through p38 MAP kinase and inhibition of this pathway reduces binding of lipids. Inhibition of p38 MAP kinase will elicit a wide spread antiinflammatory response which may alleviate some of the deleterious processes in cardiovascular tissues. This article explores the potential for the actions of p38 MAP kinase inhibitors directed at Proteoglycan Synthesis in vascular smooth muscle to contribute to the beneficial outcomes from targeting p38 MAP kinase for the prevention of cardiovascular disease.
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Smad and p38 MAP kinase-mediated signaling of Proteoglycan Synthesis in vascular smooth muscle
The Journal of biological chemistry, 2008Co-Authors: Harsha Dadlani, Mandy L. Ballinger, Robel Getachew, Narin Osman, Peter J. LittleAbstract:Atherosclerosis is the underlying pathological process of most cardiovascular disease. A critical component of the "response to retention" hypothesis of atherogenesis is Proteoglycan/low density lipoprotein (LDL) binding. Transforming growth factor beta (TGF-beta) is present in atherosclerotic lesions, regulates vascular smooth muscle cell (VSMC) Proteoglycan Synthesis via an unknown signaling pathway, and increases Proteoglycan/LDL binding. This pathway was investigated using the activin receptor-like kinase 5 (ALK5) inhibitor SB431542 and inhibitors of p38 MAP kinase as a possible downstream or alternative mediator. TGF-beta stimulated and SB431542 inhibited the phosphorylation of Smad2/3. In human VSMC, TGF-beta increased [(35)S]sulfate incorporation into Proteoglycans associated with a 19% increase in glycosaminoglycan (GAG) chain size by size exclusion chromatography. SB431542 caused a concentration-dependent decrease in TGF-beta-mediated [(35)S]sulfate incorporation with 92% inhibition at 3 mum. Two different p38 MAP kinase inhibitors, SB203580 and SB202190, but not the inactive analogue SB202474, concentration-dependently blocked TGF-beta-mediated [(35)S]sulfate incorporation. TGF-beta increased [(3)H]glucosamine incorporation into glycosaminoglycans by 180% and [(35)S]Met/Cys incorporation into Proteoglycan core proteins by 35% with both effects completely inhibited by SB431542. Blocking both Smad2/3 and p38 MAP kinase pathways prevented the effect of TGF-beta to increase Proteoglycan to LDL binding. TGF-beta mediates its effects on Proteoglycan Synthesis in VSMCs via the ALK5/Smad2/3 phosphorylation pathway as well as via the p38 MAP kinase signaling cascade. Further studies of downstream pathways controlling Proteoglycan Synthesis may identify potential therapeutic targets for the prevention of atherosclerosis and cardiovascular disease.
