Journal articles on the topic 'Matrix composition alteration'
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AlJamal-Naylor, Rehab, Linda Wilson, Susan McIntyre, Fiona Rossi, Beth Harrison, Mark Marsden, and David J. Harrison. "Allosteric Modulation of Beta1 Integrin Function Induces Lung Tissue Repair." Advances in Pharmacological Sciences 2012 (2012): 1–16. http://dx.doi.org/10.1155/2012/768720.
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The cellular cytoskeleton, adhesion receptors, extracellular matrix composition, and their spatial distribution are together fundamental in a cell's balanced mechanical sensing of its environment. We show that, in lung injury, extracellular matrix-integrin interactions are altered and this leads to signalling alteration and mechanical missensing. The missensing, secondary to matrix alteration and cell surface receptor alterations, leads to increased cellular stiffness, injury, and death. We have identified a monoclonal antibody against β1 integrin which caused matrix remodelling and enhancement of cell survival. The antibody acts as an allosteric dual agonist/antagonist modulator of β1 integrin. Intriguingly, this antibody reversed both functional and structural tissue injury in an animal model of degenerative disease in lung.
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Andersen, Pål Østebø, Steinar Evje, Hans Kleppe, and Svein Magne Skjæveland. "A Model for Wettability Alteration in Fractured Reservoirs." SPE Journal 20, no. 06 (December 18, 2015): 1261–75. http://dx.doi.org/10.2118/174555-pa.
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Summary We present a mathematical model for wettability alteration (WA) in fractured reservoirs. Flow in the reservoir is modeled by looking at a single fracture surrounded by matrix on both sides. Water is injected into the formation with a chemical component that enters the matrix and adsorbs onto the rock surface. These changes of the mineral surface are assumed to alter the wettability toward a more water-wet state, which leads to enhanced recovery by spontaneous imbibition. This can be viewed as a representation of “smart water” injection in which the ionic composition of injection brine affects recovery. The WA is described by shifting curves for relative permeability and capillary pressure from curves representing preferentially oil-wet (POW) conditions toward curves representing more-water-wet conditions. The numerical code was successfully compared with ECLIPSE for the specific case in which a fixed wetting state is assumed. Also, the relevance of the WA model was illustrated by modeling a spontaneous-imbibition experiment in which only a modification of the brine composition led to a change in oil recovery. The model can predict sensitivity to matrix properties such as wettability, permeability, and fracture spacing and to external parameters such as schedule of brine compositions and injection rate. Our model illustrates that one cannot use conventional reservoir modeling to capture accurately the behavior we observe. The rate of recovery and the level of recovery have a strong dependency on the component chemistry and its distribution. A significant feature of gradual WA by injecting a component is that the rate of fluid transfer is maintained between matrix and fracture. The resulting recovery profile after water breakthrough can behave close to linear as opposed to the square-root-of-time profile that is observed when the wetting state is fixed (Rangel-German and Kovscek 2002). The water will typically break through early as dictated by the initial POW state, but a higher final recovery will be obtained because higher saturations can imbibe. Improved understanding of the coupling between WA controlled by water/rock chemistry and fracture/matrix flow is highly relevant for gaining more insight into recovery from naturally fractured reservoirs.
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Gerner, C., C. Seelos, and G. Sauermann. "Alteration of Nuclear Matrix Protein Composition during Apoptosis in Rat Embryo Cells." Experimental Cell Research 238, no. 2 (February 1998): 472–80. http://dx.doi.org/10.1006/excr.1997.3866.
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HURT, Sean M., Alan E. RUBIN, and John T. WASSON. "Fractionated matrix composition in CV3 Vigarano and alteration processes on the CV parent asteroid." Meteoritics & Planetary Science 47, no. 6 (June 2012): 1035–48. http://dx.doi.org/10.1111/j.1945-5100.2012.01372.x.
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Trakshel, G. M., and M. D. Maines. "Characterization of glutathione S-transferases in rat kidney. Alteration of composition by cis-platinum." Biochemical Journal 252, no. 1 (May 15, 1988): 127–36. http://dx.doi.org/10.1042/bj2520127.
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We have developed chromatographic and mathematical protocols that allowed the high resolution of glutathione S-transferase (GST) subunits, and the identification of a previously unresolved GST monomer in rat kidney cytosol; the monomer was identified tentatively as subunit 6. Also, an aberrant form of GST 7-7 dimer appeared to be present in the kidney. This development was utilized to illustrate the response of rat kidney GST following cis-platinum treatment in vivo. Rat kidney cytosol was separated into three ‘affinity families’ of GST activity after elution from a GSH-agarose matrix. The affinity peaks were characterized by quantitative differences in their subunit and dimeric compositions as determined by subsequent chromatography on a cation-exchange matrix and specific activity towards substrates. By use of these criteria, the major GST dimers of affinity peaks were tentatively identified. The major GST dimers in peak I were GST 1-1 and 1-2, in affinity peak II it was GST 2-2, and in peak III they were GST 3-3 and 7-7. GST 3-6 and/or 4-6, which have not been previously resolved in kidney cytosol, were also present in peak II. Alterations in the kidney cytosolic GST composition of male rats were detected subsequent to the administration of cis-platinum (7.0 mg/kg subcutaneously, 6 days). This treatment caused a pronounced alteration in the GST profile, and the pattern of alteration was markedly different from that reported for other chemicals in the kidney or in the liver. In general, the cellular contents of the GSTs of the Alpha and the Mu classes decreased and increased respectively. It is postulated that the decrease in the Alpha class of GSTs by cis-platinum treatment may be related to renal cortical damage and the loss of GSTs in the urine. The increase in the Mu class of GSTs could potentially stem from a lowered serum concentration of testosterone; the latter is a known effect of cis-platinum treatment.
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Kassiri, Zamaneh, and Rama Khokha. "Myocardial extra-cellular matrix and its regulation by metalloproteinases and their inhibitors." Thrombosis and Haemostasis 93, no. 02 (2005): 212–19. http://dx.doi.org/10.1160/th04-08-0522.
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SummaryCardiovascular disease poses a major health care burden in the Western world. Following myocardial injuries, ventricular remodelling and dysfunction ensue, which can eventually culminate in heart failure. An important event in left ventricular (LV) remodelling is alteration of the extracellular matrix (ECM) integrity, the structural network that interconnects the myocardial components. The critical role of ECM remodelling in cardiac dilation and heart failure was recognized more than a decade ago, and the molecular factors responsible for this process are now being explored. Abnormal ECM turnover is primarily brought about by an imbalance in the activity of matrix metalloproteinases (MMPs) that degrade ECM components, and their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs). Here we provide an overview of composition of the cardiac ECM, and alterations in ECM regulatory proteins, MMPs and TIMPs, in human heart disease. We also discuss the role of TIMPs, MMPs, and a disintegrin and metalloproteinase (ADAMs) enzymes in cardiac development and function as learned through genetically altered mouse models.
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Kubyshkin, Anatoly, Olga Pisareva, Yevgenia Bessalova, and Irina Fomochkina. "The prospects of using the silver nanoparticles composition in sodium alginate matrix." MATEC Web of Conferences 315 (2020): 09001. http://dx.doi.org/10.1051/matecconf/202031509001.
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A wide range of anti-inflammatory properties of the solution of nanosilver has found its application in medical practice. In this work, nano-silver was used in the treatment of burn wounds in combination with a proteinase inhibitor. An experimental model of a second-degree burn with the use of a nano-silver solution in combination therapy is accompanied by a decrease in the inhibitory potential at the local level and stimulation of regeneration processes, which indicates the anti-inflammatory effects of nano-silver particles. There is also a decrease in the morphological signs of inflammation in the burned areas of the skin of the therapeutic use of a solution of nano-silver. The results indicate that nano-silver solution for prophylactic and therapeutic use has the ability to block a cascade of inflammatory reactions in the focus of damage, as it is evidenced by a decrease in the degree of alteration and intensification of reparative processes in damaged tissues.
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Mitchell, Roger H., Andrea Giuliani, and Hugh O’Brien. "What is a Kimberlite? Petrology and Mineralogy of Hypabyssal Kimberlites." Elements 15, no. 6 (December 1, 2019): 381–86. http://dx.doi.org/10.2138/gselements.15.6.381.
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Hypabyssal kimberlites are subvolcanic intrusive rocks crystallised from mantle-derived magmas poor in SiO2 and rich in CO2 and H2O. They are complex, hybrid rocks containing significant amounts of mantle-derived fragments, primarily olivine with rare diamonds, set in a matrix of essentially magmatic origin. Unambiguous identification of kimberlites requires careful petrographic examination combined with mineral compositional analyses. Melt inclusion studies have shown that kimberlite melts contain higher alkali concentrations than previously thought but have not clarified the ultimate origin of these melts. Because of the hybrid nature of kimberlites and their common hydrothermal alteration by fluids of controversial origin (magmatic and/or crustal), the composition of primary kimberlite melts remains unknown.
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Zandanel, Amber, Kirsten B. Sauer, Marlena Rock, Florie A. Caporuscio, Katherine Telfeyan, and Edward N. Matteo. "Impacts of Crystalline Host Rock on Repository Barrier Materials at 250 °C: Hydrothermal Co-Alteration of Wyoming Bentonite and Steel in the Presence of Grimsel Granodiorite." Minerals 12, no. 12 (December 1, 2022): 1556. http://dx.doi.org/10.3390/min12121556.
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Direct disposal of dual-purpose canisters (DPC) has been proposed to streamline the disposal of spent nuclear fuel. However, there are scenarios where direct disposal of DPCs may result in temperatures in excess of the specified upper temperature limits for some engineered barrier system (EBS) materials, which may cause alteration within EBS materials dependent on local conditions such as host rock composition, chemistry of the saturating groundwaters, and interactions between barrier materials themselves. Here we report the results of hydrothermal experiments reacting EBS materials—bentonite buffer and steel—with an analogue crystalline host rock and groundwater at 250 °C. Experiment series explored the effect of reaction time on the final products and the effects of the mineral and fluid reactants on different steel types. Post-mortem X-ray diffraction, electron microprobe, and scanning electron microscopy analyses showed characteristic alteration of both bentonite and steel, including the formation of secondary zeolite and calcium silicate hydrate minerals within the bentonite matrix and the formation of iron-bearing clays and metal oxides at the steel surfaces. Swelling clays in the bentonite matrix were not quantitatively altered to non-swelling clay species by the hydrothermal conditions. The combined results of the solution chemistry over time and post-mortem mineralogy suggest that EBS alteration is more sensitive to initial groundwater chemistry than the presence of host rock, where limited potassium concentration in the solution prohibits conversion of the smectite minerals in the bentonite matrix to non-swelling clay species.
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Hara, Eiki, Yoshitomo Honda, Osamu Suzuki, Tomonari Tanaka, and Naoyuki Matsumoto. "Epigallocatechin Gallate-Modified Gelatins with Different Compositions Alter the Quality of Regenerated Bones." International Journal of Molecular Sciences 19, no. 10 (October 19, 2018): 3232. http://dx.doi.org/10.3390/ijms19103232.
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Bone quality is a significant indicator of the result of bone treatments. However, information regarding the quality of regenerated bones is limited. The study investigates the effect of different compositions of vacuum heated epigallocatechin gallate-modified gelatins sponge (vhEGCG-GS) on the quality of regenerated bones in critical size defects (9 mm) of rat calvariae. Five different compositions of vhEGCG-GSs containing the same amount of EGCG and different amounts of gelatin were tested. Following four weeks after implantation, the harvested regenerated bones were evaluated by using micro-computed tomography analysis, histological evaluation (hematoxylin-eosin and Villaneueva Goldner staining), picrosirius red-staining with polarized microscopic observation for collagen maturation, and Fourier transform infrared spectroscopy microscopy and imaging analysis for mineral-matrix ratio. The results indicated that increasing content of gelatin in the vhEGCG-GSs promoted bone and osteoid formation but yielded porous bones. Furthermore, tissue mineral density decreased and the maximum mineral-matrix ratio increased. In contrast, vhEGCG-GSs containing smaller amount of gelatin formed mature collagen matrix in the regenerated bones. These results suggest that the alteration of composition of vhEGCG-GSs affected the bone forming capability and quality of regenerated bone and provides valuable insight for the fabrication of new bone substitute materials.
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Feng, Xiaodong, Marcia G. Tonnesen, Shaker A. Mousa, and Richard A. F. Clark. "Fibrin and Collagen Differentially but Synergistically Regulate Sprout Angiogenesis of Human Dermal Microvascular Endothelial Cells in 3-Dimensional Matrix." International Journal of Cell Biology 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/231279.
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Angiogenesis is a highly regulated event involving complex, dynamic interactions between microvascular endothelial cells and extracellular matrix (ECM) proteins. Alteration of ECM composition and architecture is a hallmark feature of wound clot and tumor stroma. We previously reported that during angiogenesis, endothelial cell responses to growth factors are modulated by the compositional and mechanical properties of a surrounding three-dimensional (3D) extracellular matrix (ECM) that is dominated by either cross-linked fibrin or type I collagen. However, the role of 3D ECM in the regulation of angiogenesis associated with wound healing and tumor growth is not well defined. This study investigates the correlation of sprout angiogenesis and ECM microenvironment using in vivo and in vitro 3D angiogenesis models. It demonstrates that fibrin and type I collagen 3D matrices differentially but synergistically regulate sprout angiogenesis. Thus blocking both integrin alpha v beta 3 and integrin alpha 2 beta 1 might be a novel strategy to synergistically block sprout angiogenesis in solid tumors.
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Sutton, S. J., and J. B. Maynard. "Petrology, mineralogy, and geochemistry of sandstones of the lower Huronian Matinenda Formation: resemblance to underlying basement rocks." Canadian Journal of Earth Sciences 30, no. 6 (June 1, 1993): 1209–23. http://dx.doi.org/10.1139/e93-103.
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Bulk chemistry, mineralogy, mineral chemistry, cathodoluminescence characteristics, and textural data are used to constrain provenance and the role of postdepositional alteration processes in sandstones of the lower Huronian Matinenda Formation. Samples studied are from the Elliot Lake – Blind River and Agnew Lake areas, which experienced subgreenschist and biotite-grade greenschist metamorphism, respectively. Both areas, but particularly the lower grade area, contain some K-rich samples, with much of the K in detrital-appearing K-feldspar. In places K-feldspar is partially replaced by potassic mica. Plagioclase (mostly albite) is rare in the Elliot Lake – Blind River samples, and only common along a few horizons in the Agnew Lake section. It is suggested that the predominance of K-feldspar over plagioclase and the high K/Na ratios indicate a K-rich source area and in particular a weathered granite source. Framework mineralogy is found to be similar to material reported from sub-Matinenda weathered granite. The abundance of fine-grained micaceous matrix within the Matinenda varies considerably among samples, and the composition of the mica varies, correlating strongly with bulk chemistry. Some matrix has clearly been generated by alteration of framework K-feldspar. Feldspar alteration may have liberated K that was carried to the underlying regolith where it was fixed by weathering-product clay minerals. Fluids involved in alteration do not appear to have pervasively affected the Matinenda in either the Elliot Lake – Blind River or the Agnew Lake area.
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., Sathyashankarasharma, Gurumurthy ., Gowri Shankar, A. Kini, M. Shettar, and P. Hiremath. "Aging Kinetics and Microstructural Features of Al6061-SiC+B4C Stir Cast Hybrid Composites." International Journal of Automotive and Mechanical Engineering 16, no. 4 (December 30, 2019): 7211–24. http://dx.doi.org/10.15282/ijame.16.4.2019.04.0538.
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The purpose of the current metallurgical work is to analyse the mechanical property alteration and microstructure evaluation of Al6061 hybrid composites by age hardening treatment using three different aging temperatures. Al6061 hybrid composites reinforced with B4C and SiC particles have been manufactured using two-stage stir casting method. The optical micrographs were analysed for the dispersivity of the reinforcements in the matrix. To assure the type of reinforcements in the matrix SEM analysis was carried out. It was found thatduring solutionising and aging at 100, 150 and 200°C, presence of SiC and B4C particles in the hybrid Al6061 matrix composites showed substantial improvement in hardness compared to that of the base alloy. Transmission electron microscopy (TEM) was used to identify the intermetallic phases, morphology and orientation of the particulates responsible for the peak aging behaviour. It was observed that while aging at 100°C excellent peak hardness values are observed in the composite group with well-distributed fine precipitates of Mg2Si along grain boundaries as well as within the grains. The composition Al6061-3B3S composites showed an additional secondary intermetallic phase viz., α-Al12Fe3SiMg along with Mg2Si, which is responsible for the superior aging behaviour over other compositions.
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Dihazi, Gry H., Marwa Eltoweissy, Olaf Jahn, Björn Tampe, Michael Zeisberg, Hauke S. Wülfrath, Gerhard A. Müller, and Hassan Dihazi. "The Secretome Analysis of Activated Human Renal Fibroblasts Revealed Beneficial Effect of the Modulation of the Secreted Peptidyl-Prolyl Cis-Trans Isomerase A in Kidney Fibrosis." Cells 9, no. 7 (July 18, 2020): 1724. http://dx.doi.org/10.3390/cells9071724.
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The secretome is an important mediator in the permanent process of reciprocity between cells and their environment. Components of secretome are involved in a large number of physiological mechanisms including differentiation, migration, and extracellular matrix modulation. Alteration in secretome composition may therefore trigger cell transformation, inflammation, and diseases. In the kidney, aberrant protein secretion plays a central role in cell activation and transition and in promoting renal fibrosis onset and progression. Using comparative proteomic analyses, we investigated in the present study the impact of cell transition on renal fibroblast cells secretome. Human renal cell lines were stimulated with profibrotic hormones and cytokines, and alterations in secretome were investigated using proteomic approaches. We identified protein signatures specific for the fibrotic phenotype and investigated the impact of modeling secretome proteins on extra cellular matrix accumulation. The secretion of peptidyl-prolyl cis-trans isomerase A (PPIA) was demonstrated to be associated with fibrosis phenotype. We showed that the in-vitro inhibition of PPIA with ciclosporin A (CsA) resulted in downregulation of PPIA and fibronectin (FN1) expression and significantly reduced their secretion. Knockdown studies of PPIA in a three-dimensional (3D) cell culture model significantly impaired the secretion and accumulation of the extracellular matrix (ECM), suggesting a positive therapeutic effect on renal fibrosis progression.
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Pomazansky, Bogdan, Richard Monkhorov, Tat’yana Antonova, Vladimir Malkovets, Alexey Kulagin, Marina Shalkina, Viktoria Batyr, and Alexey Sobakin. "Unaltered kimberlite of Internationalnaya pipe (Mirny field)." Ores and metals, no. 3 (November 3, 2021): 101–13. http://dx.doi.org/10.47765/0869-5997-2021-10022.
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The porphyry kimberlite block (intrusive coherent kimberlite, after Scott-Smith, 2013) on the deep horizons of the Internationalnaya pipe is characterized by the lack of olivine macrocryst serpentinization, and the minimum degree of postmagmatic alteration in the matrix minerals. Garnet keliphitization and the composition of olivine and phlogopite outer zones are due to the interaction of deep minerals and the surrounding kimberlite melt at depth. The rapid melt crystallization contributed to the heterogeneous magma structure represented by the macrocryst (porphyry) and aphyric schlieren.
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Park, Juwon, Christina Lee, and Michelle D. Tallquist. "PDGFRα ablation leads to alteration of ECM and immune cell composition in the lung." Journal of Immunology 204, no. 1_Supplement (May 1, 2020): 74.20. http://dx.doi.org/10.4049/jimmunol.204.supp.74.20.
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Abstract Fibroblasts are the major cells responsible for tissue homeostasis, repair, and remodeling. In particular, PDGFRα is expressed by mesenchymal progenitors in the lung that constitute the myofibroblast population which transiently express α-SMA during alveologenesis. In the fibrotic lungs, PDGFRα+ lineages can differentiate into subpopulation of myofibroblasts which regulate tissue repair and remodeling. Although the contribution of PDGFRα+lineage to lung development and fibrosis are particularly well-known, their roles in the lung parenchyma at baseline are less characterized. To explore how PDGFRα+ fibroblasts affect extracellular matrix in baseline lung, we used genetic ablation of PDGFRα+ fibroblasts using Pdgfrα-CreERT2-driven expression of diphtheria toxin A. Histologically, thin mesenchyme was observed in fibroblast-ablated adult lungs. A majority of PDGFRα+ lineages are Col1a1-GFP+ cells, but PDGFRα-ablated lungs showed a significant decrease in the number of PDGFRα lineage and Col1a1-GFP+ cells. In addition, decreased expressions of ECM genes, such as Col1a1, Col1a2, and fibronectin-1 were observed in PDGFRα-ablated lungs. These data indicated that PDGFRα+ cells are a major source of extracellular proteins and PDGFRα ablation leads to alteration of ECM homeostasis in the baseline lung. Flow cytometry analysis of the lung tissues revealed that PDGFRα ablation resulted in elevated numbers of leukocytes and neutrophils. However, fibroblast loss did not affect macrophage numbers. These data suggested that fewer PDGFRα+ cells or loss of ECM or both can affect the recruitment of immune cells in the lung. In summary, changes in ECM environment by PDGFRα ablation leads to altered immune cell composition in the lung.
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Nakonieczny, Damian Stanislaw, Aleš Slíva, Zbigniew Paszenda, Marianna Hundáková, Gabriela Kratošová, Sylva Holešová, Justyna Majewska, Piotr Kałużyński, Sajjan Kumar Sathish, and Gražyna Simha Martynková. "Simple Approach to Medical Grade Alumina and Zirconia Ceramics Surface Alteration via Acid Etching Treatment." Crystals 11, no. 10 (October 12, 2021): 1232. http://dx.doi.org/10.3390/cryst11101232.
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In order for bioceramics to be further used in composites and their applications, it is important to change the surface so that the inert material is ready to interact with another material. Medical grade alumina and zirconia ceramic powders have been chemically etched with three selected acidic mixtures. Powder samples were taken for characterization, which was the key to evaluating a successful surface change. Changes in morphology, together with chemical composition, were studied using scanning electron microscopy, phase composition using X-ray diffraction methods, and nitrogen adsorption/desorption isotherms are used to evaluate specific surface area and porosity. The application of HF negatively affected the morphology of the material and caused agglomeration. The most effective modification of ceramic powders was the application of a piranha solution to obtain a new surface and a satisfactory degree of agglomeration. The prepared micro-roughness of the etched ceramic would provide an improved surface of the material either for its next step of incorporation into the selected matrix or to directly aid in the attachment and proliferation of osteoblast cells.
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Hong, Hanlie, Zhaohui Li, Muzhuang Yang, Ping Xiao, and Huijuan Xue. "Kaolin in the net-like horizon of laterite in Hubei, south China." Clay Minerals 44, no. 1 (March 2009): 51–66. http://dx.doi.org/10.1180/claymin.2009.044.1.51.
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AbstractThe clay mineralogy and chemical composition of the white veins, red matrix and both Fe- and Mn-bearing nodules occurring in a laterite profile in Hubei, south China were investigated using X-ray diffraction, scanning electron microscopy equipped with an energy-dispersive spectrometer, and high-resolution transmission electron microscopy. The results show that the mineral components of the red matrix are mainly quartz, kaolinite, halloysite, goethite and minor illite, whereas the white net-like veins contain mostly quartz, kaolinite, halloysite, and illite. In the net-like horizon, the chemical index of alteration (CIA, the ratio of Al2O3/(Al2O3+CaO+K2O+Na2O)) and the TiO2/Al2O3 ratio are 89.8% and 0.021 for the white vein and 90.7% and 0.025 for the red matrix, respectively. Both white-vein and red-matrix components have similar TiO2/Al2O3 ratios, and are similar to the ratio 0.027 of the unaltered bedrock. The similarity in TiO2/Al2O3 values indicates that all three portions of the laterite soil share the same origin. Also, although the white-vein and red-matrix components differ in Fe2O3 abundance, the similar CIA values do imply similar degrees of alteration. The Fe-bearing and Mn-bearing nodules were produced by the local accumulation of Fe2O3 and MnO, respectively. Halloysite in the weathering profile occurs in two different morphologies, tubular and platy crystals. Tubular halloysite occurs both in the red matrix and the Fe-bearing nodule whereas platy halloysite occurs only in the white vein and Mn-bearing nodule assemblages. Crystallization of small tubular halloysite from Si and Al concretions in the red matrix is observed, indicating that the morphology of these crystals in the weathering environment is mainly controlled by Fe3+ cations, whereas platy halloysite may be derived from the hydration of kaolinite.
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Mitrovic, Danica, Natasa Djokovic, Dragana Zivotic, Achim Bechtel, Olga Cvetkovic, and Ksenija Stojanovic. "Characterisation of lignite lithotypes from the “Kovin” deposit (Serbia) - implications from petrographic, biomarker and isotopic analysis." Journal of the Serbian Chemical Society 82, no. 6 (2017): 739–54. http://dx.doi.org/10.2298/jsc161122030m.
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Four lignite lithotypes (matrix coal, xylite-rich coal, mixture of matrix and mineral-rich coal and mixture of matrix and xylite-rich coal), originating from the Kovin deposit, were investigated in detail. The paper was aimed to determine the main maceral, biomarker and isotopic (?13C) characteristics of investigated lithotypes. Based on these results the sources and depositional environment of organic matter in 4 lithotypes were established. These samples were also used as substrates for investigation of the influence of diagenetic alteration on ?13C signatures of biomarkers, as well as for assessment of the most convenient utilization for each lithotype. The investigated lithotypes differ in accordance with the composition of huminite macerals. Xylite-rich coal notably distinguishes from other lithotypes beacuse of the highest content of conifer resins vs. epicuticular waxes. The mixture of matrix and mineral-rich coal is characterised by the greatest contribution of algae and fungi and the most intense methanotrophic activity at the time of deposition. In all coal lithotypes diagenetic aromatisation influenced isotopic composition of individual biomarkers. Xylite-rich coal has the poorest grindability properties. However, this coal lithotype is the most suitable for fluidized bed gasification, whereas the mixture of matrix and mineral-rich coal has the lowest applicability for this process. The calorific value decreases in order: xylite-rich coal > matrix coal > mixture of matrix and xylite-rich coal > mixture of matrix and mineral-rich coal. The increase of organic carbon content and calorific value is controlled by the increase of contribution of wood vegetation vs. herbaceous peat-forming plants, as well as by stability of water table during peatification.
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Abdellatef, Shimaa A., Riho Tange, Takeshi Sato, Akihiko Ohi, Toshihide Nabatame, and Akiyoshi Taniguchi. "Nanostructures Control the Hepatocellular Responses to a Cytotoxic Agent “Cisplatin”." BioMed Research International 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/925319.
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In drug discovery programs, the alteration betweenin vivoandin vitrocellular responses to drug represents one of the main challenges. Since the variation in the native extracellular matrix (ECM) betweenin vivoand 2Din vitroconditions is one of the key reasons for such discrepancies, thus the utilization of substrate that likely mimics ECM characteristics (topography, stiffness, and chemical composition) is needed to overcome such problem. Here, we investigated the role of substrate nanotopography as one of the major determinants of hepatic cellular responses to a chemotherapeutic agent “cisplatin.” We studied the substratum induced variations in cisplatin cytotoxicity; a higher cytotoxic response to cisplatin was observed for cells cultured on the nanopattern relative to a flat substrate. Moreover, the nanofeatures with grating shapes that mimic the topography of major ECM protein constituents (collagen) induced alterations in the cellular orientation and chromatin condensation compared to flat surfaces. Accordingly, the developments of biomimetic substrates with a particular topography could have potentials in drug development analyses to reflect more physiological mimicry conditionsin vitro.
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Götze, Jens, Klaus Stanek, Gerardo Orozco, Moritz Liesegang, and Tanja Mohr-Westheide. "Occurrence and Distribution of Moganite and Opal-CT in Agates from Paleocene/Eocene Tuffs, El Picado (Cuba)." Minerals 11, no. 5 (May 18, 2021): 531. http://dx.doi.org/10.3390/min11050531.
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Agates in Paleocene/Eocene tuffs from El Picado/Los Indios, Cuba were investigated to characterize the mineral composition of the agates and to provide data for the reconstruction of agate forming processes. The volcanic host rocks are strongly altered and fractured and contain numerous fissures and veins mineralized by quartz and chalcedony. These features indicate secondary alteration and silicification processes during tectonic activities that may have also resulted in the formation of massive agates. Local accumulation of manganese oxides/hydroxides, as well as uranium (uranyl-silicate complexes), in the agates confirm their contemporaneous supply with SiO2 and the origin of the silica-bearing solutions from the alteration processes. The mineral composition of the agates is characterized by abnormal high bulk contents of opal-CT (>6 wt%) and moganite (>16 wt%) besides alpha-quartz. The presence of these elevated amounts of “immature” silica phases emphasize that agate formation runs through several structural states of SiO2 with amorphous silica as the first solid phase. A remarkable feature of the agates is a heterogeneous distribution of moganite within the silica matrix revealed by micro-Raman mapping. The intensity ratio of the main symmetric stretching-bending vibrations (A1 modes) of alpha-quartz at 465 cm−1 and moganite at 502 cm−1, respectively, was used to depict the abundance of moganite in the silica matrix. The zoned distribution of moganite and variations in the microtexture and porosity of the agates indicate a multi-phase deposition of SiO2 under varying physico-chemical conditions and a discontinuous silica supply.
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Adnan, Noor Quratul Aine, and Anika Zafiah M. Rus. "Sound Absorption Properties of Dwi Matrix Renewable and Synthetic Polymer." Advanced Materials Research 974 (June 2014): 38–42. http://dx.doi.org/10.4028/www.scientific.net/amr.974.38.
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This research is to study the acoustic property of biopolymer foam and commercial consumer petroleum based epoxy foam. This is to evaluate the influence of proportion ratio of polymers matrix and filler namely as Titanium Dioxide (TiO2) towards the sound absorption coefficient (α) at different frequencies level (Hz). Biopolymer foam was prepared based on in-house synthesized monomer from vegetable oil with commercial polymethane diphenyl diisocyanate (Modified Polymeric-MDI) with the different proportion ratio of TiO2. The acoustic property of samples was examined by using an impedance tube test according to ASTM E-1050 of sound absorption coefficient (α). It was observed that epoxy gives higher value of α that is 0.9995 but shifted to higher absorption frequencies level as the TiO2loading increased. Meanwhile the lowest composition ratio of TiO2loading in biopolymer foam gives the best value of α at the lowest absorption frequency level as compared to epoxy composition ratios. Evidently, different percentage ratio of TiO2varied α value which influence the absorption frequency level (Hz). Hence, the minimal alteration on the filler loading of epoxy or biopolymer greatly influences the acoustic performance of both polymers. Meanwhile, the commercial foam of noise reduction coefficient, NRC values of commercial foam were decreasing with the increasing proportion ratio of TiO2while, the NRC values of biopolymer foam were increased as the TiO2ratio was increased. This is due to the sound coefficient in polymeric foam is related to the effect of the interaction between different characteristic for both material (biopolymer foam and commercial foam) and morphology of foam.
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Kapsiotis, Argyrios. "Composition and alteration of Cr-spinels from Milia and Pefki serpentinized mantle peridotites (Pindos Ophiolite Complex, Greece)." Geologica Carpathica 65, no. 1 (February 1, 2014): 83–95. http://dx.doi.org/10.2478/geoca-2013-0006.
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Abstract The Pindos Ophiolite rocks include variably serpentinized peridotites derived from a harzburgitic and subordinately dunitic mantle. In the serpentinized matrix of these rocks pseudomorphic (mesh, bastite) and non-pseudomorphic (interpenetrating, type-2 hourglass) textures were recognized. Chromian spinel (Cr-spinel) is anhedral to subhedral and often replaced by a porous opaque phase. Chemistry data show that Cr-spinel cores retain their original composition, having Cr#[Cr/(Cr + Al)] that ranges between 0.45 and 0.73, and Mg#[Mg/(Mg + Fe2+)] that varies between 0.52 and 0.65, accompanied by low content in TiO2 ( < 0.11wt. %). The relatively wide variation of their Cr# values reflects that the studied peridotites were produced by variable degrees of melting. It is likely that the Pindos peridotites represent mantle residues originally formed in a mid-ocean ridge (MOR) environment, which were subsequently entrapped as part of a mantle wedge above a supra-subduction zone (SSZ) regime. Cr-spinel adjacent to clinochlore systematically displays limited compositional and textural zoning along grain boundaries and fractures. However, the degree of peridotite serpentinization does not correlate with the abundance of zoning effects in accessory Cr-spinel. Thus, Cr-spinel zoning is thought to represent a secondary feature obtained during the metamorphic evolution of the host peridotites. Core to rim compositional trends are expressed by MgO and Al2O3 impoverishment, mainly compensated by Cr2O3 and FeO increases. Such chemical trends are produced as a result of Cr-spinel re-equilibration with the surrounding serpentine, and their subsequent replacement by ferrian (Fe3+-rich) chromite and clinochlore, respectively, during a brief, fluid assisted, greenschist facies metamorphism episode (T > 300 °C). The limited occurrence of ferrian chromite with high Fe3+# values suggests that elevated oxidizing conditions were prevalent only on a local scale during Cr-spinel alteration
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Maldonado, Maricela, and Jin Nam. "The Role of Changes in Extracellular Matrix of Cartilage in the Presence of Inflammation on the Pathology of Osteoarthritis." BioMed Research International 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/284873.
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Osteoarthritis (OA) is a degenerative disease that affects various tissues surrounding joints such as articular cartilage, subchondral bone, synovial membrane, and ligaments. No therapy is currently available to completely prevent the initiation or progression of the disease partly due to poor understanding of the mechanisms of the disease pathology. Cartilage is the main tissue afflicted by OA, and chondrocytes, the sole cellular component in the tissue, actively participate in the degeneration process. Multiple factors affect the development and progression of OA including inflammation that is sustained during the progression of the disease and alteration in biomechanical conditions due to wear and tear or trauma in cartilage. During the progression of OA, extracellular matrix (ECM) of cartilage is actively remodeled by chondrocytes under inflammatory conditions. This alteration of ECM, in turn, changes the biomechanical environment of chondrocytes, which further drives the progression of the disease in the presence of inflammation. The changes in ECM composition and structure also prevent participation of mesenchymal stem cells in the repair process by inhibiting their chondrogenic differentiation. This review focuses on how inflammation-induced ECM remodeling disturbs cellular activities to prevent self-regeneration of cartilage in the pathology of OA.
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Hezel, Dominik C., Johanna S. Wilden, Daniel Becker, Sonja Steinbach, Frank Wombacher, and Markus Harak. "Fe isotope composition of bulk chondrules from Murchison (CM2): Constraints for parent body alteration, nebula processes and chondrule-matrix complementarity." Earth and Planetary Science Letters 490 (May 2018): 31–39. http://dx.doi.org/10.1016/j.epsl.2018.03.013.
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Anisimov, Volodymyr Mykolaovych, Volodymyr Volodymyrovych Anisimov, and Tibor Krenicky. "Properties Prediction of Linear Block-Polyurethanes Based on the Mixtures of Simple Oligoethers." Management Systems in Production Engineering 27, no. 4 (December 1, 2019): 217–20. http://dx.doi.org/10.1515/mspe-2019-0034.
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AbstractPolyurethanes are materials usable in wide spectrum of applications. This article is aimed at the properties tailoring of selected polymers by an alteration in initial materials. To achieve that goal, we proposed form the polyurethane matrix by mixing materials that have a different ratio of the initial components. Mathematical model has been developed that describes relationship of structure and strength, deformation, rheological and tribotechnical characteristics of linear block-polyurethanes based on oligoether blends. Oligoethers blend samples were obtained by injection moulding on an automatic thermoplastication machine with varying proportions of the starting components over the whole concentration range. A significant change of properties over the whole concentration range was observed and compositions with unique combination of characteristics have been determined. Obtained dependencies allow to predict the composition of the binary mixture with a tailored level of strength, deformation, rheological and tribotechnical characteristics. The obtained results are fully consistent with the practical experience of processing and exploitation of initial polyurethanes.
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Caravà, Elena, Paola Moretto, Ilaria Caon, Arianna Parnigoni, Alberto Passi, Evgenia Karousou, Davide Vigetti, Jessica Canino, Ilaria Canobbio, and Manuela Viola. "HA and HS Changes in Endothelial Inflammatory Activation." Biomolecules 11, no. 6 (May 29, 2021): 809. http://dx.doi.org/10.3390/biom11060809.
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Cardiovascular diseases are a group of disorders caused by the presence of a combination of risk factors, such as tobacco use, unhealthy diet and obesity, physical inactivity, etc., which cause the modification of the composition of the vessel’s matrix and lead to the alteration of blood flow, matched with an inflammation condition. Nevertheless, it is not clear if the inflammation is a permissive condition or a consequent one. In order to investigate the effect of inflammation on the onset of vascular disease, we treated endothelial cells with the cytokine TNF-α that is increased in obese patients and is reported to induce cardiometabolic diseases. The inflammation induced a large change in the extracellular matrix, increasing the pericellular hyaluronan and altering the heparan sulfate Syndecans sets, which seems to be related to layer permeability but does not influence cell proliferation or migration nor induce blood cell recruitment or activation.
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Galgani, L., and A. Engel. "Changes in optical characteristics of surface microlayers hint to photochemically and microbially-mediated DOM turnover in the upwelling region off Peru." Biogeosciences Discussions 12, no. 23 (December 7, 2015): 19373–421. http://dx.doi.org/10.5194/bgd-12-19373-2015.
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Abstract. The coastal upwelling system off Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. During the Meteor (M91) cruise to the Peruvian upwelling system in 2012, we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples at 38 stations determining DOC concentration, amino acid composition, marine gels, CDOM and bacterial and phytoplankton abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. We identified five fluorescent components of the CDOM pool, of which two had excitation/emission characteristics of protein-like fluorophores and were highly enriched in the SML. CDOM composition and changes in spectral slope properties suggested a local microbial release of HMW DOM directly in the SML as a response to light exposure in this extreme environment. Our results suggest that microbial and photochemical processes play an important role for the production, alteration and loss of optically active substances in the SML.
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Stepicheva, Nadezda, Rohana Liyanage, Jackson Lay, Robert Dienglewicz, and Gisela Erf. "Abnormal morphology of melanosomes in the autoimmune vitiligo-prone Smyth line chicken does not appear to be due to alteration in lipid composition (83.16)." Journal of Immunology 184, no. 1_Supplement (April 1, 2010): 83.16. http://dx.doi.org/10.4049/jimmunol.184.supp.83.16.
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Abstract The Smyth line (SL) chicken is an important animal model for autoimmune vitiligo. SL vitiligo is multifactorial in nature including genetic susceptibility, immune system components and environmental triggers. Genetic susceptibility to SL vitiligo appears to be manifested in part by an inherent melanocyte defect. SL melanosomes (pigment-carrying organelles) have irregular-shaped membranes with pigmented extensions that may be due to abnormal lipid composition. Lipids can affect protein topology and trafficking (and hence protein degradation and presentation), membrane stability and oxidative stress resistance. To compare melanosomal lipids from SL and control lines of chickens, melanosomes were isolated from growing feathers of 4-week-old SL, Brown line (parental control) and Light Brown Leghorn (vitiligo-resistant) chickens and lipids were extracted. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) combined with thin-layer chromatography (TLC) was used to determine expression differences in different classes of lipids by using TLC-MALDI imaging technique. Total fatty acid composition was examined by gas chromatography-mass spectrometry (GC-MS) of fatty acid methyl esters. Statistical analysis of preliminary data shows no significant differences in total fatty acid and phospholipid composition in melanosomes from SL and control chickens. Hence, lipid composition may not explain the melanosomal abnormalities observed in SL melanocytes.
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Kamineni, D. C., K. V. Ticknor, and T. T. Vandergraaf. "Occurrence, composition and radionuclide sorption characteristics of illite from a fractured granite pluton, Southeastern Manitoba, Canada." Clay Minerals 21, no. 5 (December 1986): 909–24. http://dx.doi.org/10.1180/claymin.1986.021.5.05.
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AbstractLow-dip fractures in the Lac du Bonnet granite pluton, SE Manitoba, contain abundant illite. Petrographic examination showed that the illite has three modes of occurrence: (i) alteration product of biotite, (ii) microfracture (< 1 mm width) filling, (iii) macrofracture (> 1 mm) filling. Microprobe analyses of these three types of illites in a single sample gave distinct compositional characteristics that defined an evolutionary trend, depicting Al2O3 enrichment, on an Al2O3−(K2O + Na2O)−(MgO + FeO) triangular diagram. White micas in the rock matrix adjacent to illite-bearing fractures have higher K and Al contents than all the three types of illites, implying that they formed under different conditions. The sorption of four radionuclides, 137Cs, 147Pm, 241Am and 90Sr, under oxic conditions on illite-bearing polished sections was also investigated, using autoradiography combined with petrographic examination. Illite showed greater sorption compared with other minerals present in the polished sections.
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Arolt, Christoph, Moritz Meyer, Franziska Hoffmann, Svenja Wagener-Ryczek, David Schwarz, Lisa Nachtsheim, Dirk Beutner, et al. "Expression Profiling of Extracellular Matrix Genes Reveals Global and Entity-Specific Characteristics in Adenoid Cystic, Mucoepidermoid and Salivary Duct Carcinomas." Cancers 12, no. 9 (August 31, 2020): 2466. http://dx.doi.org/10.3390/cancers12092466.
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The composition of the extracellular matrix (ECM) plays a pivotal role in tumour initiation, metastasis and therapy resistance. Until now, the ECM composition of salivary gland carcinomas (SGC) has not been studied. We quantitatively analysed the mRNA of 28 ECM-related genes of 34 adenoid cystic (AdCy; n = 11), mucoepidermoid (MuEp; n = 14) and salivary duct carcinomas (SaDu; n = 9). An incremental overexpression of six collagens (including COL11A1) and four glycoproteins from MuEp and SaDu suggested a common ECM alteration. Conversely, AdCy and MuEp displayed a distinct overexpression of COL27A1 and LAMB3, respectively. Nonhierarchical clustering and principal component analysis revealed a more specific pattern for AdCy with low expression of the common gene signature. In situ studies at the RNA and protein level confirmed these results and indicated that, in contrast to MuEp and SaDu, ECM production in AdCy results from tumour cells and not from cancer-associated fibroblasts (CAFs). Our findings reveal different modes of ECM production leading to common and distinct RNA signatures in SGC. Of note, an overexpression of COL27A1, as in AdCy, has not been linked to any other neoplasm so far. Here, we contribute to the dissection of the ECM composition in SGC and identified a panel of deferentially expressed genes, which could be putative targets for SGC therapy and overcoming therapeutic resistance.
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Zeni, Patrick, Eva Doepker, Ulf Schulze Topphoff, Sabine Huewel, Tobias Tenenbaum, and Hans-Joachim Galla. "MMPs contribute to TNF-α-induced alteration of the blood-cerebrospinal fluid barrier in vitro." American Journal of Physiology-Cell Physiology 293, no. 3 (September 2007): C855—C864. http://dx.doi.org/10.1152/ajpcell.00470.2006.
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The epithelial cells of the choroid plexus separate the central nervous system from the blood forming the blood-cerebrospinal fluid (CSF) barrier. The choroid plexus is the main source of CSF, whose composition is markedly changed during pathological disorders, for example regarding matrix metalloproteases (MMPs) and tissue inhibitors of matrix metalloproteases (TIMPs). In the present study, we analyzed the impact of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) on the blood-CSF barrier using an in vitro model based on porcine choroid plexus epithelial cells (PCPEC). TNF-α evoked distinct inflammatory processes as shown by mRNA upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. The cytokine caused a drastic decrease in transepithelial electrical resistance within several hours representing an enhanced permeability of PCPEC monolayers. In addition, the distribution of tight junction proteins was altered. Moreover, MMP activity in PCPEC supernatants was significantly increased by TNF-α, presumably due to a diminished expression of TIMP-3 that was similarly observed. MMP-2, -3, and -9 as well as TIMP-1 and -2 were also analyzed and found to be differentially regulated by the cytokine. The TNF-α-induced breakdown of the blood-CSF barrier could partially be blocked by the MMP inhibitor GM-6001. Our results show a contribution of MMPs to the inflammatory breakdown of the blood-CSF barrier in vitro. Thus TNF-α may mediate the binding of leukocytes to cellular adhesion molecules and the transmigration across the blood-CSF barrier.
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Hu, Yan, Jin Cui, Han Liu, Sicheng Wang, Qirong Zhou, Hao Zhang, Jiawei Guo, et al. "Single-cell RNA-sequencing analysis reveals the molecular mechanism of subchondral bone cell heterogeneity in the development of osteoarthritis." RMD Open 8, no. 2 (September 2022): e002314. http://dx.doi.org/10.1136/rmdopen-2022-002314.
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The cellular composition and underlying spatiotemporal transformation processes of subchondral bone in osteoarthritis (OA) remain unknown. Herein, various cell subsets from tibial plateau of patients with OA are identified, and the mechanism of subchondral microstructure alteration is elaborated using single-cell RNA sequencing technique. We identified two novel endothelial cell (EC) populations characterised by either exosome synthesis and inflammation response or vascular function and angiogenesis. Three osteoblast (OB) subtypes are introduced, separately related to vascularisation, matrix manufacturing and matrix mineralisation. The distinct roles and functions of these novel phenotypes in OA development are further discussed as well as interaction network between these subpopulations. The variation tendency of each population is testified in a destabilisation of the medial meniscus mouse model. The identification of cell types demonstrates a novel taxonomy and mechanism for ECs and OBs inside subchondral bone area provides new insights into the physiological and pathological behaviours of subchondral bone in OA pathogenesis.
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Barber, D. J. "Phyllosilicates and other layer-structured materials in stony meteorites." Clay Minerals 20, no. 4 (December 1985): 415–54. http://dx.doi.org/10.1180/claymin.1985.020.4.01.
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AbstractCurrent thinking regarding the possible origins and probable evolutionary histories of meteorites is summarized. Selected data concerning the composition, petrology and other characteristics of the CI and CM groups of stony meteorites in which layered minerals principally occur are then presented. Layered compounds, mainly phyllosilicates, are shown to form a major part of the fine-grained matrix of the CI and CM meteorites, which are classified as carbonaceous chondrites. The results of recent investigations of matrix mineralogy are reviewed, with particular emphasis on the findings of electron microscopy. Several forms of Fe-Mg-serpentine have been identified as the principal phyllosilicates. ‘Poorly-characterized phases’ in CM meteorites have proved to be tochilinite and intergrowths of tochilinite with serpentines. The results generally indicate that the phyllosilicates and most other matrix minerals formed by aqueous alteration in the regoliths of the CI and CM parent bodies; but there is isotopic evidence for the incorporation of components and possibly mineral grains which predate the solar nebula. It is concluded that more detailed chemical and mineralogical information about the phyllosilicates and associated minerals will enable useful constraints to be placed on the possible identities of their precursors and the environments in which both they and the matrix minerals formed.
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Preeti, Ahankare, Sridharan Gokul, and Patankar Sangeeta. "Role of Laminin in Oral Carcinogenesis." Journal of Dentists 7 (March 8, 2019): 22–26. http://dx.doi.org/10.12974/2311-8695.2019.07.4.
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Oral carcinogenesis is characterized by significant alterations occurring at the phenotypic and genotypic level resulting in uncontrolled proliferation and evasion of apoptosis. With growing tumor mass, a switch of metabolism and angiogenesis becomes important for the further development of the disease. Invasion and subsequent metastasis of the malignant cells are basic requirement for tumor promotion and progression. Cell migration plays an important in embryogenesis, inflammatory immune response, wound healing and cancer invasion. One of the important factors responsible for the tumor progression is the alteration seen in extracellular matrix proteins. Extracellular matrix (ECM) includes a group of structural proteins, glycoproteins, and proteoglycans that function as a physical scaffold to maintain tissue structure and provides biochemical signals to modulate cellular function. Basement membranes are thin layers of ECM that form the supporting structure under epithelial and endothelial cells. The protein composition of basement membrane is mainly inclusive of type IV collagen, laminins, entactins, and proteoglycans. Laminin is biologically active part of the basement membrane and influences cell differentiation, migration and cell adhesion. They are an important and biologically active component of the basal lamina, influencing cell differentiation, migration, and adhesion. Laminin reflects the integrity of basement membrane better than the other extracellular matrix (ECM) proteins and thus, may be used as a marker suggestive of the basement membrane status during tumorigenesis. Oral squamous cell carcinoma is an important epithelial malignancy and altered laminin expression in OSCC is an important process in its invasion and metastasis. An understanding of the role of laminin in OSCC may aid in its utility as a biomarker to determine the prognosis and treatment planning of OSCC.
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Weiskirchen, Ralf, Sabine Weiskirchen, and Frank Tacke. "Recent advances in understanding liver fibrosis: bridging basic science and individualized treatment concepts." F1000Research 7 (June 27, 2018): 921. http://dx.doi.org/10.12688/f1000research.14841.1.
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Hepatic fibrosis is characterized by the formation and deposition of excess fibrous connective tissue, leading to progressive architectural tissue remodeling. Irrespective of the underlying noxious trigger, tissue damage induces an inflammatory response involving the local vascular system and the immune system and a systemic mobilization of endocrine and neurological mediators, ultimately leading to the activation of matrix-producing cell populations. Genetic disorders, chronic viral infection, alcohol abuse, autoimmune attacks, metabolic disorders, cholestasis, alterations in bile acid composition or concentration, venous obstruction, and parasite infections are well-established factors that predispose one to hepatic fibrosis. In addition, excess fat and other lipotoxic mediators provoking endoplasmic reticulum stress, alteration of mitochondrial function, oxidative stress, and modifications in the microbiota are associated with non-alcoholic fatty liver disease and, subsequently, the initiation and progression of hepatic fibrosis. Multidisciplinary panels of experts have developed practice guidelines, including recommendations of preferred therapeutic approaches to a specific cause of hepatic disease, stage of fibrosis, or occurring co-morbidities associated with ongoing loss of hepatic function. Here, we summarize the factors leading to liver fibrosis and the current concepts in anti-fibrotic therapies.
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Tomašić, Nenad, Radek Škoda, Vladimir Bermanec, and Marin Šoufek. "Crystal chemistry and microfeatures of gadolinite imprinted by pegmatite formation and alteration evolution." American Mineralogist 105, no. 11 (November 1, 2020): 1647–55. http://dx.doi.org/10.2138/am-2020-7355.
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Abstract Gadolinite [REE2Fe2+Be2Si2O10] is a common mineral in certain types of rare element and rare earth element (REL-REE) pegmatites. Changes in pegmatite environment during and after gadolinite formation may be devised by studying its crystal-chemical properties and a thorough observation of microfeatures in the mineral matrix. Post-crystallization processes in pegmatite might trigger alteration mechanisms in gadolinite like in other REE-rich pegmatite minerals, whereby various late-magmatic or metasomatic events may affect mineral chemistry. Three gadolinite samples originating from various pegmatite occurrences in southern Norway offer an excellent opportunity in studying post-crystallization evolution of the pegmatites; by determining their crystallographic, chemical, and micro-textural features, imprints of the related processes in the pegmatites have been characterized in this study. Relevant mineral information was collected in recrystallization experiments of fully or slightly metamictized gadolinite samples and subsequent XRD analyses. Micro-Raman spectroscopy, electron microprobe analysis (EMPA), and scanning electron microscope–backscattered electron–energy-dispersive X-ray spectroscopy (SEM-BSE-EDS) analyses were employed to retrieve micro-chemical properties and related micro-textural features of the mineral matrix. With a reference to the gadolinite supergroup, a general alteration path can be envisaged outlining the pegmatite evolution and suggesting the occurrence of the secondary REE mineral phases: altered gadolinite domains prove Ca enrichment with a tendency toward the hingganite composition, while a slight fluorine increase and sporadic secondary fluorite occurrence imply a significant role of fluorine as a complexing agent in the dissolution-reprecipitation mechanism of metasomatic alteration in the mineral. Micro-Raman spectra show improved vibration statistics for the altered gadolinite domains, which could be linked to the substitution of rare earth elements (REE) by Ca and a possible increase of structural ordering within the gadolinite structure, being at the same time an indication of structural healing of metamictized domains by metasomatic processes. A study of microfeatures in the complex silicates like gadolinite proves to be an excellent tool to trace post-crystallization processes in a pegmatitic environment. With a slight redistribution of radionuclides during an alteration in gadolinite, a moderate precaution has to be taken when selecting gadolinite for U-Th-Pb dating.
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Slukovskaya, Marina V., Irina P. Kremenetskaya, Svetlana V. Drogobuzhskaya, and Andrey I. Novikov. "Sequential Extraction of Potentially Toxic Metals: Alteration of Method for Cu-Ni Polluted Peat Soil of Industrial Barren." Toxics 8, no. 2 (June 2, 2020): 39. http://dx.doi.org/10.3390/toxics8020039.
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An evaluation of fraction composition and transformation of metal compounds emitted by metal ore processing enterprises and accumulated in soils is crucial for assessing the environmental risks of pollution and ecosystem benefit of remediation. The aim of this study was to develop a suitable sequential fractional procedure for metal pollutants for the peat soils matrix in the impact zone of a Cu-Ni smelter. Three experiment series were performed: (a) the study of the effect of ammonium acetate buffer pH in the range of 3.7–7.8 on the soil metal extraction; (b) the study of the effect of additional volume and frequency of soil treatment with solutions on the content of water-soluble, ammonium acetate extractable, and 0.1 N HNO3 extractable fractions; and, (c) the determination of the metal fraction composition in the modified technique. Soil treatment with ammonium acetate buffer with a pH range of 4.5–5.5 was the most appropriate for the determination of mobile compounds of Cu and other metals in highly polluted peat soil. Triple soil treatment with water and ammonium acetate is necessary for the complete extraction of the water-soluble and exchangeable fractions, respectively. Additionally, we propose a procedure of full extraction of the exchangeable metal fraction from peat soils while using single treatment with 0.1 N HNO3. This scheme allows evaluating geochemical mobility of metals and current environmental harm of polluted soils with a high content of organic matter.
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Yuanita, Evana, Yuli Amalia Husnil, Myrna Ariati Mochtar, Rahma Lailani, and Mochamad Chalid. "The Effect of Alkalization Treatment on Fiber-Matrix Compatibility in Natural Fiber Reinforced Composite." Key Engineering Materials 847 (June 2020): 28–33. http://dx.doi.org/10.4028/www.scientific.net/kem.847.28.
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This work was aimed to investigate the effect of alkalization treatment on the fiber-matrix interfacial interaction and hence their compatibility. Kenaf fiber was treated using a 6% NaOH solution for 8 hours. The composites were produced by mixing the treated fiber with PP at various temperatures, duration, and fiber composition. Alteration on the surface chemistry of the fiber was identified by performing FTIR analysis. The surface energy of the treated fiber was mathematically derived from the contact angle measurement results. The compatibility level between treated fiber and PP matrix was visualized through FESEM analysis. Tensile strength tests were also conducted to obtain data necessary for exploring the relationship between the thermodynamic aspects of the fiber-matrix interfacial interaction and the mechanical properties of the composites. The FTIR spectra show that there was significant increase in the %transmittance at wavelength range of 3100-3600 cm-1 indicating that O-H groups were degraded during treatment. However, the polar component of the surface energy for treated fiber was instead higher compared to the untreated one. The SEM images show that there are no noticeable reduction in the size of the treated fibers as expected. On the other hand, the tensile strength of the PP-treated fibers composites reached its highest value when the matrix were loaded with fibers at the lowest percentage i.e. 5%.
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Novembre, Daniela, Domingo Gimeno, Piergiulio Cappelletti, and Sossio Fabio Graziano. "A case study of zeolitization process: “Tufo Rosso a Scorie Nere” (Vico volcano, Italy): inferences for a general model." European Journal of Mineralogy 33, no. 3 (June 2, 2021): 315–28. http://dx.doi.org/10.5194/ejm-33-315-2021.
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Abstract. This paper focuses on the authigenic mineralization processes acting on “Tufo Rosso a Scorie Nere” (TRS), i.e. one of the main pyroclastic units of the Vico stratovolcano (Latium, Italy). The pyroclastic deposits appear in general massive and made of “black vitreous vesiculated juvenile scoriae”, immersed in an ashy matrix lithified after zeolitization processes. The main minerals are chabazite and phillipsite, and the zeolitic content is locally variable, reaching 68 % wt. Zeolites grow replacing both amorphous fraction and pre-existing phases, occurring inside both matrix and scoriae. Concerning scoriae, zeolitization moves from the rim to the core of the scoriaceous fragment as a function of (a) temperature of the fluids and (b) permeability (primary or secondary). Composition of parental fresh glass and that of zeolitized rocks is compatible with trachyte chemistry, lightly undersaturated in SiO2, and the alteration processes modified the parental rock chemical features. Zeolites genesis is ascribed to a “geoautoclave-like system”, and zeolites display a Si/Al ratio similar to that of the parental glasses. TRS presents promising mineralogical characteristics as supplementary cementitious material in the production of mixed cements.
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Bozkaya, Ömer, Ivan A. Baksheev, Nurullah Hanilçi, Gülcan Bozkaya, Vsevolod Y. Prokofiev, Yücel Öztaş, and David A. Banks. "Tourmaline Composition of the Kışladağ Porphyry Au Deposit, Western Turkey: Implication of Epithermal Overprint." Minerals 10, no. 9 (September 7, 2020): 789. http://dx.doi.org/10.3390/min10090789.
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The Kışladağ porphyry Au deposit occurs in a middle Miocene magmatic complex comprising three different intrusions and magmatic-hydrothermal brecciation related to the multiphase effects of the different intrusions. Tourmaline occurrences are common throughout the deposit, mostly as an outer alteration rim around the veins with lesser amounts disseminated in the intrusions, and are associated with every phase of mineralization. Tourmaline mineralization has developed as a tourmaline-rich matrix in brecciated zones and tourmaline-quartz and/or tourmaline-sulfide veinlets within the different intrusive rocks. Tourmaline was identified in the tourmaline-bearing breccia zone (TBZ) and intrusive rocks that had undergone potassic, phyllic, and advanced argillic alteration. The tourmaline is present as two morphological varieties, aggregates of fine crystals (rosettes, fan-shaped) and larger isolated crystals and their aggregates. Four tourmaline generations (tourmaline I to IV) have different compositions and substitutions. Tourmaline I in TBZ and INT#1 is distinguished by the highest Fetot and enriched in Fe3+. Tourmalines II and III occur as fine aggregates, accompanied by the formation of isolated crystals and are characterized by lower Fetot and Fe3+. Tourmaline IV is characterized by the lowest Fetot, enriched in Cl, and has the highest proportion of X-site vacancy among all the tourmalines. Tourmaline I may be attributed to the potassic stage in INT#1 and early tourmaline in TBZ. Tourmalines II and III from INT#1 and the TBZ could be referred to the phyllic stage. The low Fe content in tourmaline is caused by the simultaneous deposition of sulfide minerals. Tourmaline IV from the TBZ and tourmaline II from INT#3 are distinguished by the high X-site vacancy proportion up to the formation of X-site vacant species as well as enriched in Cl; they can be attributed to the argillic stage of the hydrothermal process. The textural and especially chemical data of the tourmaline from the Kışladağ Au deposit provide information on the physico-chemical conditions during the porphyry to epithermal transition and subsequent epithermal overprinting.
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Ohira, Y., W. Yasui, F. Kariya, T. Tanaka, I. Kitajima, I. Maruyama, S. Nagaoka, C. Sekiguchi, and W. E. Hinds. "Spaceflight effects on beta-adrenoceptor and metabolic properties in rat plantaris." Journal of Applied Physiology 81, no. 1 (July 1, 1996): 152–55. http://dx.doi.org/10.1152/jappl.1996.81.1.152.
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Effects of 14 days of spaceflight on beta-adrenoceptor (beta-AR), mitochondrial enzyme activities, and fiber type composition were studied in plantaris muscles of male adult Sprague-Dawley rats. The beta-AR was analyzed in cross sections by quantitative autoradiography. The maximum binding capacity (Bmax) of beta-AR was significantly lowered (approximately 29%) after flight, but the recovery was not completed within 9 days in 1-G environment. Because the dissociation constant remained unchanged, it is suggested that the changes in the Bmax were caused by the alteration of receptor number. The activities of succinate dehydrogenase (SDH) measured in whole homogenates were subnormal (approximately -24%) in muscles sampled approximately 5 h after flight but they were normalized during 9 days of recovery. The percent composition of fiber types and beta-hydroxyacyl CoA dehydrogenase (HAD) activity did not change significantly due to spaceflight. It is suggested that the spaceflight-induced decrease of the Bmax of beta-AR in plantaris was accompanied by a lowered activity of a mitochondrial inner-membrane enzyme SDH but not a matrix enzyme HAD.
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Perego, Carla, Cristina Vanoni, Silvia Massari, Andrea Raimondi, Sandra Pola, Maria Grazia Cattaneo, Maura Francolini, Lucia Maria Vicentini, and Grazia Pietrini. "Invasive behaviour of glioblastoma cell lines is associated with altered organisation of the cadherin-catenin adhesion system." Journal of Cell Science 115, no. 16 (August 15, 2002): 3331–40. http://dx.doi.org/10.1242/jcs.115.16.3331.
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As little is known about the role of cadherin-mediated cell-cell adhesion in astrocytes and its alteration in migrating and invasive glioblastomas, we investigated its molecular composition and organisation in primary cultured astrocytes and the T98G and U373MG glioblastoma cell lines. Biochemical and morphological analysis indicated that all three cell types express all of the structural components of the adhesion system, including the LIN-7 PDZ protein,a novel component involved in the organisation of the junctional domain in epithelia and neurons. However, only the astrocytes and T98G cells generated and maintained mature adhesive junctional domains to which LIN-7 was recruited. Alterations in the junctional domain of U373MG cells were associated with higher motility in a poly-L-lysine migration assay. When the T98G cells were cultured on Matrigel matrix, they acquired invasive properties but, despite unchanged cadherin adhesion system protein levels, the invasive T98G cell-cell contacts failed to accumulate LIN-7 and failed to mature. These results identify the LIN-7 PDZ protein as a marker of cell adhesion maturity and cell invasion and indicate that instability and disorganisation of cadherin-mediated junctions rather than reduced expression of cadherin-catenin system components are required to promote migration and invasiveness in glioblastoma cell lines.
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Krebber, Merle M., Christian G. M. van Dijk, Robin W. M. Vernooij, Maarten M. Brandt, Craig A. Emter, Christoph D. Rau, Joost O. Fledderus, et al. "Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Extracellular Matrix Remodeling during Left Ventricular Diastolic Dysfunction and Heart Failure with Preserved Ejection Fraction: A Systematic Review and Meta-Analysis." International Journal of Molecular Sciences 21, no. 18 (September 14, 2020): 6742. http://dx.doi.org/10.3390/ijms21186742.
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Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are pivotal regulators of extracellular matrix (ECM) composition and could, due to their dynamic activity, function as prognostic tools for fibrosis and cardiac function in left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction (HFpEF). We conducted a systematic review on experimental animal models of LVDD and HFpEF published in MEDLINE or Embase. Twenty-three studies were included with a total of 36 comparisons that reported established LVDD, quantification of cardiac fibrosis and cardiac MMP or TIMP expression or activity. LVDD/HFpEF models were divided based on underlying pathology: hemodynamic overload (17 comparisons), metabolic alteration (16 comparisons) or ageing (3 comparisons). Meta-analysis showed that echocardiographic parameters were not consistently altered in LVDD/HFpEF with invasive hemodynamic measurements better representing LVDD. Increased myocardial fibrotic area indicated comparable characteristics between hemodynamic and metabolic models. Regarding MMPs and TIMPs; MMP2 and MMP9 activity and protein and TIMP1 protein levels were mainly enhanced in hemodynamic models. In most cases only mRNA was assessed and there were no correlations between cardiac tissue and plasma levels. Female gender, a known risk factor for LVDD and HFpEF, was underrepresented. Novel studies should detail relevant model characteristics and focus on MMP and TIMP protein expression and activity to identify predictive circulating markers in cardiac ECM remodeling.
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Aplin, J. D., and L. J. Foden. "Defective adhesion to extracellular matrix leads to altered social behaviour in cultured fibroblasts." Journal of Cell Science 76, no. 1 (June 1, 1985): 199–211. http://dx.doi.org/10.1242/jcs.76.1.199.
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We describe the properties of variant mouse fibroblasts selected for poor adhesion to growth substratum containing subcellular matrix accumulated by adherent cells at confluence. The variant cells adhere to virgin plastic and grow normally to confluence in the presence of serum. After subculture and reseeding onto the same surface the cells initially adhere, but after a further 2 days of growth they retract into aggregates and detach. If the aggregates are dispersed and cells reseeded onto the same surface they remain rounded. However, if the same cells are added back to virgin plastic they adhere and grow normally. The retraction can be abolished by treating the subcellular matrix-coated plastic with papain. This behaviour therefore reflects the ability of the cells to modify the composition of the underlying substratum during growth. The variant cells also exhibit retraction 2 days after seeding on a surface previously containing wild-type cells at confluence, while wild-type cells do not retract on subcellular matrix deposited by variants. This shows that the variant behaviour arises not from a deficiency in the subcellular matrix, but from an alteration in the adhesive capacity of the cells. The results are interpreted in terms of three putative adhesion mechanisms: cell-cell adhesion in confluent monolayers and aggregates; ‘early’ type cell-substratum adhesion, which occurs during culture on virgin plastic; and ‘late’ type cell-substratum adhesion occurring on surfaces containing accumulated subcellular matrix. The variant phenotype is characterized by a deficiency in the last of these. It is also associated with an increased ability to grow in suspension culture at high dilution.
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Yevdokimova, N. Y., and A. S. Yefimov. "Effects of wheat germ agglutinin and concanavalin A on the accumulation of glycosaminoglycans in pericellular matrix of human dermal fibroblasts. A comparison with insulin." Acta Biochimica Polonica 48, no. 2 (June 30, 2001): 563–72. http://dx.doi.org/10.18388/abp.2001_3939.
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The effect of insulin, wheat germ agglutinin (WGA), peanut agglutinin (PNA) and concanavalin A (ConA) on [3H]glucosamine incorporation into pericellular glycosaminoglycans (GAGs) was investigated in two lines of cultured human dermal fibroblasts. Insulin and WGA stimulated [3H]glucosamine incorporation into hyaluronic acid (HA) and heparan sulphate (HS) without any alteration of chondroitin sulphate (CS) and dermatan sulphate (DS) contents. ConA increased [3H]glucosamine incorporation into HS, CS and DS, but had no effect on [3Hglucosamine incorporation into HA. PNA affected neither the content, nor the composition of GAGs. In contrast to PNA, ConA and WGA stimulated glycolysis and demonstrated an evident antiproliferative effect on dermal fibroblasts. Thus, both the insulin-like action of WGA and ConA on cultured dermal fibroblasts and the differences between the effects of lectins on modulation of GAGs synthesis appear to be determined by their chemical structure.
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Brandt, Elisa F., Maike Baues, Theresa H. Wirtz, Jan-Niklas May, Petra Fischer, Anika Beckers, Björn-Carsten Schüre, et al. "Chemokine CXCL10 Modulates the Tumor Microenvironment of Fibrosis-Associated Hepatocellular Carcinoma." International Journal of Molecular Sciences 23, no. 15 (July 23, 2022): 8112. http://dx.doi.org/10.3390/ijms23158112.
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Hepatocellular carcinoma (HCC) constitutes a devastating health burden. Recently, tumor microenvironment-directed interventions have profoundly changed the landscape of HCC therapy. In the present study, the function of the chemokine CXCL10 during fibrosis-associated hepatocarcinogenesis was analyzed with specific focus on its impact in shaping the tumor microenvironment. C57BL/6J wild type (WT) and Cxcl10 knockout mice (Cxcl10−/−) were treated with diethylnitrosamine (DEN) and tetrachloromethane (CCl4) to induce fibrosis-associated HCCs. Cxcl10 deficiency attenuated hepatocarcinogenesis by decreasing tumor cell proliferation as well as tumor vascularization and modulated tumor-associated extracellular matrix composition. Furthermore, the genetic inactivation of Cxcl10 mediated an alteration of the tumor-associated immune response and modified chemokine/chemokine receptor networks. The DEN/CCl4-treated Cxcl10−/− mice presented with a pro-inflammatory tumor microenvironment and an accumulation of anti-tumoral immune cells in the tissue. The most striking alteration in the Cxcl10−/− tumor immune microenvironment was a vast accumulation of anti-tumoral T cells in the invasive tumor margin. In summary, our results demonstrate that CXCL10 exerts a non-redundant impact on several hallmarks of the tumor microenvironment and especially modulates the infiltration of anti-tumorigenic immune cells in HCC. In the era of microenvironment-targeted HCC therapies, interfering with CXCL10 defines a novel asset for further improvement of therapeutic strategies.
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Mamikutty, Norshalizah, Zar Chi Thent, and Farihah Haji Suhaimi. "Fructose-Drinking Water Induced Nonalcoholic Fatty Liver Disease and Ultrastructural Alteration of Hepatocyte Mitochondria in Male Wistar Rat." BioMed Research International 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/895961.
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Background.Nonalcoholic fatty liver disease (NAFLD) is one of the complications of the metabolic syndrome. It encompasses a wide range of disease spectrum from simple steatosis to liver cirrhosis. Structural alteration of hepatic mitochondria might be involved in the pathogenesis of NAFLD.Aims.In the present study, we used a newly established model of fructose-induced metabolic syndrome in male Wistar rats in order to investigate the ultrastructural changes in hepatic mitochondria that occur with fructose consumption and their association with NAFLD pathogenesis.Methods.The concentration of fructose-drinking water (FDW) used in this study was 20%. Six male Wistar rats were supplemented with FDW 20% for eight weeks. Body composition and metabolic parameters were measured before and after 8 weeks of FDW 20%. Histomorphology of the liver was evaluated and ultrastructural changes of mitochondria were assessed with transmission electron micrograph.Results.After 8 weeks of fructose consumption, the animals developed several features of the metabolic syndrome. Moreover, fructose consumption led to the development of macrovesicular hepatic steatosis and mitochondrial ultrastructural changes, such as increase in mitochondrial size, disruption of the cristae, and reduction of matrix density.Conclusion.We conclude that in male Wistar rat 8-week consumption of FDW 20% leads to NAFLD likely via mitochondrial structural alteration.
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Tyagi, Chetna, and Ambika Devi. "Alteration of structural, optical and electrical properties of CdSe incorporated polyvinyl pyrrolidone nanocomposite for memory devices." Journal of Advanced Dielectrics 08, no. 03 (June 2018): 1850020. http://dx.doi.org/10.1142/s2010135x18500200.
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The important enhancement in the structural, dielectric and optical properties of pure polymer and CdSe incorporated polyvinyl pyrrolidone has been reported in this paper. The surface morphology of CdSe/PVP nanocomposite film is studied by using scanning electron microscopy (SEM). The chemical composition of different elements has been reported using energy dispersive X-ray (EDX) spectrum. The structure of polymer nanocomposite is determined with the help of X-ray diffraction (XRD) spectrum and is observed to be hexagonal. Particle size, intercrystalline separation, interplanner spacing, lattice parameters, strain and dislocation factors are calculated using XRD results. Fourier transform infrared spectroscopy (FTIR) and Photoluminescence (PL) analysis have been studied in order to check the possible interaction between CdSe quantum dots and polyvinyl pyrrolidone (PVP) matrix. The ac conductivity of CdSe/PVP nanocomposite is found to be higher as compared to pure polymers. The highest value of conductivity observed at 60203 Hz and at 523 K is found to be [Formula: see text][Formula: see text]Sm[Formula: see text]. Comparative study of dielectric constant, dielectric losses, dissipation factor, electric modulus and impedance has been performed. The semi-circles in impedance measurement for both materials show the bulk electrical properties that result in single relaxation process in CdSe/PVP nanocomposite.
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HOLT, SUZAN J., WILLIAM A. CRESS, and JOHANNES VAN STADEN. "Evidence for dynamic alteration in histone gene clusters of Caenorhabditis elegans: a topoisomerase II connection?" Genetical Research 79, no. 1 (February 2002): 11–22. http://dx.doi.org/10.1017/s0016672301005390.
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Chromatin integrity is maintained throughout the cell cycle through repair mechanisms and intrinsically by the ordered packaging of DNA in association with histone proteins; however, aberrant rearrangements within and between chromosomes do occur. The role of the nuclear matrix protein topoisomerase II (TopoII) in generating chromosome breakpoints has been a focus of recent investigations. TopoII preferentially binds in vitro to scaffold-associated regions (SARs) and is involved in many DNA processing activities that require chromosome untangling. SARs, biochemically defined DNA elements rich in A+T, have been proposed to serve as structural boundaries for chromatin loops and to delineate functional domains. In our investigation of gene compartmentalization in a eukaryotic genome, SAR-associated nucleotide motifs from Drosophila were mapped in the regions of three histone gene clusters in an in silico analysis of the genome of Caenorhabditis elegans. Sites with similarity to the 15 bp consensus for TopoII cleavage were found predominantly in A+T enriched intergenic regions. Reiteration of sites matching the TopoII core consensus led to the identification of a novel core histone gene on chromosome IV and provided evidence for duplication and inversion in each of the three histone gene clusters. Breakpoint analysis of DNA flanking reiterated regions revealed potential sites for TopoII cleavage and a base composition phenomenon suggestive of a trigger for inversion events.