The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Peter A Hill - One of the best experts on this subject based on the ideXlab platform.
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Human breast cancer cell-mediated bone collagen degradation requires plasminogen activation and matrix metalloproteinase activity
Cancer Cell International, 2005Co-Authors: Hayley Morgan, Peter A HillAbstract:Background Breast cancer cells frequently metastasize to the skeleton and induce extensive bone destruction. Cancer cells produce proteinases, including matrix metalloproteinases (MMPs) and the plasminogen activator system (PAS) which promote invasion of extracellular matrices, but whether these proteinases degrade bone matrix is unclear. To characterize the role that breast cancer cell proteinases play in bone degradation we compared the effects of three human breast cancer cell lines, MDA-MB-231, ZR-75-1 and MCF-7 with those of a normal breast epithelial cell line, HME. The cell lines were cultured atop radiolabelled matrices of either mineralized or non-mineralized bone or type I collagen, the principal Organic Constituent of bone. Results The 3 breast cancer cell lines all produced significant degradation of the 3 collagenous extracellular matrices (ECMs) whilst the normal breast cell line was without effect. Breast cancer cells displayed an absolute requirement for serum to dissolve collagen. Degradation of collagen was abolished in plasminogen-depleted serum and could be restored by the addition of exogenous plasminogen. Localization of plasmin activity to the cell surface was critical for the degradation process as aprotinin, but not α_2 antiplasmin, prevented collagen dissolution. During ECM degradation breast cancer cell lines expressed urokinase-type plasminogen activator (u-PA) and uPA receptor, and MMPs-1, -3, -9,-13, and -14. The normal breast epithelial cell line expressed low levels of MMPs-1, and -3, uPA and uPA receptor. Inhibitors of both the PAS (aprotinin and PA inhibitor-1) and MMPs (CT1166 and tisue inhibitor of metalloproteinase) blocked collagen degradation, demonstrating the requirement of both plasminogen activation and MMP activity for degradation. The activation of MMP-13 in human breast cancer cells was prevented by plasminogen activator inhibitor-1 but not by tissue inhibitor of metalloproteinase-1, suggesting that plasmin activates MMP-13 directly. Conclusions These data demonstrate that breast cancer cells dissolve type I collagen and that there is an absolute requirement for plasminogen activation and MMP activity in the degradation process.
Hayley Morgan - One of the best experts on this subject based on the ideXlab platform.
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Human breast cancer cell-mediated bone collagen degradation requires plasminogen activation and matrix metalloproteinase activity
Cancer Cell International, 2005Co-Authors: Hayley Morgan, Peter A HillAbstract:Background Breast cancer cells frequently metastasize to the skeleton and induce extensive bone destruction. Cancer cells produce proteinases, including matrix metalloproteinases (MMPs) and the plasminogen activator system (PAS) which promote invasion of extracellular matrices, but whether these proteinases degrade bone matrix is unclear. To characterize the role that breast cancer cell proteinases play in bone degradation we compared the effects of three human breast cancer cell lines, MDA-MB-231, ZR-75-1 and MCF-7 with those of a normal breast epithelial cell line, HME. The cell lines were cultured atop radiolabelled matrices of either mineralized or non-mineralized bone or type I collagen, the principal Organic Constituent of bone. Results The 3 breast cancer cell lines all produced significant degradation of the 3 collagenous extracellular matrices (ECMs) whilst the normal breast cell line was without effect. Breast cancer cells displayed an absolute requirement for serum to dissolve collagen. Degradation of collagen was abolished in plasminogen-depleted serum and could be restored by the addition of exogenous plasminogen. Localization of plasmin activity to the cell surface was critical for the degradation process as aprotinin, but not α_2 antiplasmin, prevented collagen dissolution. During ECM degradation breast cancer cell lines expressed urokinase-type plasminogen activator (u-PA) and uPA receptor, and MMPs-1, -3, -9,-13, and -14. The normal breast epithelial cell line expressed low levels of MMPs-1, and -3, uPA and uPA receptor. Inhibitors of both the PAS (aprotinin and PA inhibitor-1) and MMPs (CT1166 and tisue inhibitor of metalloproteinase) blocked collagen degradation, demonstrating the requirement of both plasminogen activation and MMP activity for degradation. The activation of MMP-13 in human breast cancer cells was prevented by plasminogen activator inhibitor-1 but not by tissue inhibitor of metalloproteinase-1, suggesting that plasmin activates MMP-13 directly. Conclusions These data demonstrate that breast cancer cells dissolve type I collagen and that there is an absolute requirement for plasminogen activation and MMP activity in the degradation process.
E. A. Pogozheva - One of the best experts on this subject based on the ideXlab platform.
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Procedure for calculation of chemical indicators of ecological danger of tundra soil degradation and their validation
Contemporary Problems of Ecology, 2012Co-Authors: V. D. Vasil’evskaya, V. Ya. Grigor’ev, E. Yu. Pogozhev, E. A. PogozhevaAbstract:Based on the brief review and detailed analysis of the results obtained in the course of investigation of chemical and other characteristics of tundra soils in Russia, we developed a procedure for calculation of essential agrochemical properties of natural and disturbed soil cover in tundra to make quantitative evaluations of the ecological danger of its degradation. The initial data for calculation were the values of humus content in the soil layer 0–20 cm. They were either obtained experimentally or calculated based on correlations with soil annealing losses, hygroscopic humidity of the upper soil layer and its Organic Constituent, and the qualitative characterization of wetting and thermal conditions during the vegetation period. In order to illustrate the sequence and relevance of calculative determinations, we give a sample calculation and application of its results.
S Natarajan - One of the best experts on this subject based on the ideXlab platform.
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growth and Organic Constituent variations with salinity in excoecaria agallocha l an important halophyte
2009Co-Authors: M Jenci, S NatarajanAbstract:The present investigation was made to study the effect of different concentrations of sodium chloride and potassium chloride on growth and Organic Constituents of the seedlings of Excoecaria agallocha. The plant could survive a wide range of 100-500mM of salt concentrations. The upper limits for the survival of the seedlings were upto 500mM NaCl and 400mM KCl. The highest numbers of leaves, leaf area, fresh and dry weight were recorded at 300mM NaCl and 200mM KCl treatment. Beyond these levels, the growth parameters reduced drastically. Organic compounds such as amino acid and sugar decreased upto optimum level of 300mM NaCl and 200mM KCl and increased at higher concentrations. The starch and chlorophyll content increased upto 300mM NaCl and 200mM KCl, beyond these levels the contents decreased marginally. The proline content increased with the increasing salinity of both the salts.
Folkert Van Oort - One of the best experts on this subject based on the ideXlab platform.
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Fate of Metals Associated with Particulate Organic Matter in Soils: Unravelling Abiotic versus Biotic Processes
Revista de la Ciencia del Suelo y Nutrición Vegetal, 2008Co-Authors: Isabelle Lamy, Julien Sebastia, Jérome Labanowski, Folkert Van OortAbstract:Particulate Organic matter (POM) is operationally defined as 50-2000 um-sized Organic particles in soils. The quantity and quality of this labile Organic Constituent were shown to be strongly influenced by soil management, but the use of POM as an index for soil quality is still a matter of discussion. Recently, POM was identified as a metal-enriched Organic fraction in both metal-contaminated and uncontaminated soils. The mechanisms for such metal-enrichment remain poorly understood, as there is little information on the chemical properties of POM and the fate of metal-associated POM during biodegradation. Abiotic as well as biotic processes may be involved. In this work we report both lab and in situ investigations of various polluted or unpolluted soils, aiming to assess the intrinsic - abiotic-reactivity of soil POM fractions and to follow the status of metals in POM during biodegradation. In the lab various POM size fractions were extracted by means of physical fractionation. EDTA was used to extract metals from the isolated Organic fractions and metal concentrations were determined by AAS. Chemical reactivity of each POM fractions was quantified by potentiometric titrations. In situ, we collected undisturbed samples for sub-microscopic studies. The nature, morphology and microfabrics of soil Constituents were studied on thin sections and elemental mapping was performed by u-Xray fluorescence on decaying POM. In spite of their relatively low abundance in soil (< 5% of total bulk soil weight), the POM fractions often contain a significant proportion of the total metal stock of the soils, i.e. around 10-20% for Zn and Pb, and up to 20-30% for Cu and Cd. The results show that total metal concentrations increase with decreasing POM size, while metal extractability decreases. Each POM-size fraction provides a buffer capacity due to the presence of reactive sites but affinity for copper was found comparable between the coarse and fine POM fractions. Finer POM fractions were found however to exhibit the highest contents in reactive sites per g of Organic carbon. This suggests that with decreasing POM size, mainly due to decomposition, new reactive surface sites are generated. The micromorphological study reveals the occurrence of black opaque parts in decaying large POM fragments, which coincide with hot spots of heavy metals. Combined with microscopic observations, the analytical results suggest that metals are immobilized as organo-metallic complexes on very small POM-derived Organic fragments. Such a process would explain the increasing Organic C and metal contents frequently observed in the < 20 um fractions of metal contaminated soils, and suggest that small POM-derived Organic particles may favour long-term metal sequestration in soils. These findings show that POM is undoubtedly an interacting medium and suggest a role of fine POM fractions as a metal sink in soils and of coarser POM fractions as a metal source.