Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present research work, the preparation and characterization of bioactive glass-ceramic scaffolds for bone substitutes are described. The scaffolds were prepared by starch consolidation of bioactive glass powders belonging to the SiO2-Na2O-CaO-MgO system using three different organic starches (corn, potatoes and rice) as reported in a previous screening process. The scaffolds, characterized by scanning electron microscopy, showed a porous structure with highly interconnected pores. The pores sizes assessed by mercury intrusion porosimetry put in evidence the presence of pores of 50-100 microm. The structure of the scaffolds was investigated by X-ray diffraction and revealed the glass-ceramic nature of the obtained material. The mechanical properties of the scaffolds were evaluated by means of compressive tests on cubic samples and the obtained results demonstrated their good mechanical strength. The in vitro bioactivity of the scaffolds was tested by soaking them in a simulated body fluid (SBF) and by subsequently characterizing the soaked surfaces by SEM, EDS and X-ray diffraction. Good in vitro bioactivity was found for the starting glass and for the obtained scaffolds. Moreover, the scaffold bioresorption, tested by measuring the samples weight loss in SBF at different periods of time, showed a partial resorption of the scaffolds. Cell culture testing of the three different scaffolds indicated no differences in cell number and in alkaline phosphatase activity; the morphology of the osteoblasts showed good spreading, comparable to bulk material which was used as the control.
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PMID:Microstructural and in vitro characterization of SiO2-Na2O-CaO-MgO glass-ceramic bioactive scaffolds for bone substitutes. 1616 99

Films of Ti-Ca-P-C-O-(N), Ti-Ca-C-O-(N) and Ti-Zr-C-O-(N) were deposited by DC magnetron sputtering or ion implantation-assisted magnetron sputtering of composite targets TiC0.5 + 10%Ca10(PO4)6(OH)2, TiC0.5 + 20%(CaO + TiO2) and TiC0.5 + 10%ZrO2 in an Ar atmosphere or reactively in a gaseous mixture of Ar + 14%N2. The microstructure, elemental and phase composition of films were studied by means of X-ray diffraction, transmission electron microscopy, scanning force microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The films were characterized in terms of their hardness, Young's modulus, elastic recovery, adhesion strength, and friction and wear both in air and under physiological solution. Particular attention was paid to the analysis of deformation and fracture for various film/substrate systems during scratch testing. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments. In vitro studies involved the investigation of adhesion, spreading, and proliferation of MC3T3-E1 osteoblasts and IAR-2 epithelial cells, morphometric analysis, actin cytoskeleton, focal contacts staining, alkaline phosphatase activity and von Kossa staining of osteoblastic culture. Cell culture experiments demonstrated an increase of osteoblastic proliferation on Ca- and P-incorporated films. In vivo studies were fulfilled by subcutaneous implantation of Teflon plates coated with the tested films in mice and analysis of the population of adherent cells on their surfaces. The results obtained show that multicomponent nanostructured Ti-(Ca, Zr)-(C, N, O, P) films possess a combination of high hardness, wear resistance and adhesion strength, reduced Young's modulus, low friction coefficient and high biocompatibility.
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PMID:Multifunctional Ti-(Ca,Zr)-(C,N,O,P) films for load-bearing implants. 1653 Aug 25

A CaO-P(2)O(5)-SiO(2)-ZnO bioglass was formed by the sol-gel technique and characterized by Raman spectroscopy, X-ray diffraction, energy dispersive X-ray analysis (EDXA) and scanning electron microscopy (SEM). The surface reactivity of the resultant glass-ceramic specimens was analyzed by immersion studies in simulated body fluid (SBF). SEM-EDXS and inductively coupled plasma atomic emission spectrometry techniques were used to monitor changes in the glass surface and SBF composition. Osteoblast cell culture experiments were performed to assess the biocompatibility and the alkaline phosphatase activity. Cell counts of the osteoblasts cultured on the bioglass samples were studied and compared with the polystyrene plates. The cells cultured on the bioglass disks consistently showed a higher alkaline phosphatase activity and cell counts compared to cells cultured on either polystyrene plates or the base CaO-P(2)O(5)-SiO(2) bioglass. This was due to cell proliferation and differentiation promoted by the zinc-substituted bioglass.
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PMID:Development and in vitro characterization of sol-gel derived CaO-P2O5-SiO2-ZnO bioglass. 1713 49

One of the strategies to improve the mechanical performance of bioactive glasses for load-bearing implant devices has been the development of glass-ceramic materials. The present study aimed to evaluate the effect of a highly bioactive, fully-crystallized glass-ceramic (Biosilicate) of the system P(2)O(5)-Na(2)O-CaO-SiO(2) on various key parameters of in vitro osteogenesis. Surface characterization was carried out by scanning electron microscopy and Fourier transform infrared spectroscopy. Osteogenic cells were obtained by enzymatic digestion of newborn rat calvarial bone and by growing on Biosilicate discs and on control bioactive glass surfaces (Biosilicate) parent glass and Bioglass(R) 45S5) for periods of up to 17 days. All materials developed an apatite layer in simulated body fluid for 24h. Additionally, as early as 12 h under culture conditions and in the absence of cells, all surfaces developed a layer of silica-gel that was gradually covered by amorphous calcium phosphate deposits, which remained amorphous up to 72 h. During the proliferative phase of osteogenic cultures, the majority of cells exhibited disassembly of the actin cytoskeleton, whereas reassembly of actin stress fibers took place only in areas of cell multilayering by day 5. Although no significant differences were detected in terms of total protein content and alkaline phosphatase activity at days 11 and 17, Biosilicate supported significantly larger areas of calcified matrix at day 17. The results indicate that full crystallization of bioactive glasses in a range of compositions of the system P(2)O(5)-Na(2)O-CaO-SiO(2) may promote enhancement of in vitro bone-like tissue formation in an osteogenic cell culture system.
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PMID:In vitro osteogenesis on a highly bioactive glass-ceramic (Biosilicate). 1731 15

In our previous study, glasses with 50 P(2)O(5)-(20-15) Na(2)O-30 CaO-(0-5 mol%) TiO(2) have been prepared by the conventional melt-quenching process. MG63 cell proliferation, gene expression, in vivo biocompatibility, and bioactivity of these glasses is the concern of this study. The results showed that addition of TiO(2) in small amounts up to 5 mol% enhanced the biocompatibility of these glasses. The cell metabolic activity was conspicuous, on 3 and 5 mol% TiO(2) compositions in particular, with no significant difference from Thermanox control over a period of 21 days. The findings from the gene expression study showed that, at day 1 and on 5 mol% TiO(2) glass, core binding protein factor alpha 1 (Cbfa1) and alkaline phosphatase (ALP) showed significantly lower transcription level; however, collagen type I alpha subunit I (COLIAI) and Osteonectin (Sparc) showed no significant differences compared to the control. At day 7, all these genes transcription levels were not significantly different form the control, but at day 14, they were significantly higher than the control. Moreover, there were no significant differences detected in these genes on both 3 and 5 mol% TiO(2) glasses up to 7 days. At day 14; however, 5 mol% TiO(2) glasses showed significantly higher level than 3 mol% TiO(2) composition. This was also correlated by the presence of new bone tissue at the bone-particles interface for 5 mol% TiO(2) composition after 5 weeks of implantation in rat calvarium. Regardless of this favourable cell response and gene up-regulation, these glasses showed no evidence of apatite layer formation after 14 days incubation in SBF.
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PMID:In vitro bioactivity and gene expression by cells cultured on titanium dioxide doped phosphate-based glasses. 1741 16

We have examined the ability of bioactive sol-gel glass ceramics to support both osteoblast and osteoclast differentiation from human bone marrow cells (HBMC). Nucleated cells from human bone marrow were cultured on tissue culture plastic and on two sol-gel coatings: A2 glass-ceramic containing 54 mol % CaO/40 mol % SiO(2) and S2 glass-ceramic containing 16 mol % CaO/80 mol % SiO(2). Osteoblast differentiation was followed by measuring alkaline phosphatase (ALP) activity, mRNA levels for ALP, osteopontin, RANK ligand (RANKL), and immunofluorescent co-localization of ALP and RANKL. Osteoclasts were identified by morphology and positive staining for tartrate-resistant acid phosphatase (TRAP). ALP activity and mRNA levels were similar for cells on A2 coatings and on tissue culture plastic, but mRNA levels of osteopontin and RANKL were tenfold higher on A2 than on plastic. Cultures on A2 coatings also contained multinucleated osteoclasts staining positively for TRAP. In contrast, cells cultured on S2 coatings had the characteristics of more differentiated osteoblasts as measured by higher ALP expression. However, the levels of osteopontin and RANKL mRNA on S2 glass were lower than on A2 glass and there were fewer, weakly staining TRAP-positive multinucleate cells. Thus, sol-gel glass-ceramic materials differing in CaO/SiO(2) ratios can produce markedly different effects on the osteoblast and osteoclast differentiation from HBMC.
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PMID:Sol-gel bioactive glasses support both osteoblast and osteoclast formation from human bone marrow cells. 1763 26

Zirconia films containing Ca and P were prepared by micro-arc oxidation (MAO) of zirconium. The microstructure, in vitro bioactivity, and primary osteoblast response of the films were investigated as a function of the applied voltages in the range of 400-500 V. The results indicate that the MAO-formed zirconia films are porous and nanocrystalline, and predominantly composed of tetragonal zirconia (t-ZrO(2)). The pores and grains sizes and t-ZrO(2) content of the films tend to increase with the applied voltages. The zirconia films formed at higher voltages have higher amount of CaO and phosphate and slightly lower amount of Zr-OH groups. Although, all of the zirconia films can be fully covered by bone-like apatite after immersion in simulated body fluids (SBF) within 10 days, there exists remarkable difference in apatite-induced time. The apatite-forming ability of the films is not only ascribed to Zr-OH groups on the surfaces, but also enhanced by the CaO and phosphate ions incorporated into ZrO(2). Osteoblasts on the films are observed to attach, proliferate, and grow in good state, and have good alkaline phosphatase activity. It is suggested that the MAO-formed ZrO(2) films exhibit favorable bioactivity and biocompatibility.
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PMID:Bioactivity and osteoblast response of the micro-arc oxidized zirconia films. 1826 Jan 35

Calcium phosphate based bioceramics have been widely used for orthopedic applications due to their chemical similarity to natural bone. The Ca/P stoichiometry of calcium phosphates strongly influences their performance under biological conditions, which have not yet been fully elucidated to date. For this reason, the objective of this in vitro study was to understand the relationship between the Ca/P ratio of nano-to-micron particulate calcium phosphate substrates and their biological properties, such as osteoblast (bone-forming cell) viability, collagen production, alkaline phosphatase activity and nitric oxide (NO) production. A group of calcium phosphates with Ca/P ratios between 0.5 and 2.5 were obtained by intentionally adjusting the Ca/P stoichiometry of the initial reactants necessary for calcium phosphate precipitation. For samples with 0.5 and 0.75 Ca/P ratios, tricalcium phosphate (TCP) and Ca(2)P(2)O(7) phases were observed. In contrast, for samples with 1.0 and 1.33 Ca/P ratios, the only stable phase was TCP. For samples with a 1.5 Ca/P ratio, the TCP phase was dominant; however, small amounts of the hydroxyapatite (HA) phase started to appear. For samples with a 1.6 Ca/P ratio, the HA phase was dominant. Lastly, for samples with 2.0 and 2.5 Ca/P ratios, the CaO phase started to appear in the HA phase which was the dominant phase. Moreover, the average grain size and the average pore size decreased from micron-scale (e.g. 1370nm for a 0.5 Ca/P ratio) to nano-scale (e.g. 262nm for a 2.5 Ca/P ratio) with increasing Ca/P ratios. The porosity (%) of calcium phosphate substrates also decreased with increasing Ca/P ratios. Previous in vitro results demonstrated increased osteoblast adhesion on calcium phosphates with higher Ca/P ratios (up to 2.5). The present study showed that the collagen production by osteoblasts was similar between all the calcium phosphates but slightly lower with a 1.6 Ca/P ratio. Greater alkaline phosphatase activity by osteoblasts was observed in all the cultures with various calcium phosphates (0.5-2.5 Ca/P ratios) than in the control (only cells in culture). Ca/P ratios of <2 and 1 optimized osteoblast viability and promoted alkaline phosphatase activity in osteoblasts, respectively. However, the presence of the CaO phase in Ca/P ratios 2.0 increased osteoblast NO production and decreased osteoblast viability. In summary, this study provided evidence that the Ca/P ratio of calcium phosphate is a very important factor that should be considered when selecting nano-to-micron particulate calcium phosphates for various orthopedic applications.
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PMID:An in vitro evaluation of the Ca/P ratio for the cytocompatibility of nano-to-micron particulate calcium phosphates for bone regeneration. 1839 80

While the addition of zinc ions to bioactive ceramics has been shown to enhance the proliferation and osteogenic differentiation of osteoblast-like cells, contradictory results have been found. Therefore, the effect of zinc-releasing ceramics on cell proliferation and differentiation into osteogenic lineages requires further clarification. The aim of this study was to evaluate the effects of zinc addition on the degradation profile of three-dimensional bioactive glass scaffold, and on the proliferation and osteogenesis of human adipose stem cells (hASCs) in these scaffolds. Bioactive glass scaffolds containing Na(2)O, K(2)O, MgO, CaO, B(2)O(3), TiO(2), P(2)O(5) and SiO(2) were prepared. The degradation was evaluated by weight loss measurement, scanning electron microscopy and elemental analysis. The degradation profile of bioactive glass was shown to slow down with the addition of zinc. Qualitative live/dead staining showed that zinc addition to bioactive glass inhibits cell spreading and proliferation of hASCs. However, zinc addition had no significant effect on DNA content, alkaline phosphatase activity and osteopontin concentration of hASCs when measured quantitatively. Our results suggest that the possible stimulatory effect of addition of zinc on hASC proliferation and osteogenesis was not detected because addition of zinc slowed down the degradation rate of the studied bioactive glass scaffolds.
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PMID:Characterization of zinc-releasing three-dimensional bioactive glass scaffolds and their effect on human adipose stem cell proliferation and osteogenic differentiation. 1942 18

This study tested the hypothesis that bioactive coating glass (SiO(2)-CaO-P(2)O(5)-MgO-K(2)O-Na(2)O system), used for implant coatings, enhanced the induction of collagen type 1 synthesis and in turn enhanced the expression of downstream markers alkaline phosphatase, Runx2 and osteocalcin during osteoblast differentiation. The ions from experimental bioactive glass (6P53-b) and commercial Bioglass(TM) (45S5) were added to osteoblast-like MC3T3-E1 subclone 4 cultures as a supplemented ion extract (glass conditioned medium (GCM)). Ion extracts contained significantly higher concentrations of Si and Ca (Si, 47.9+/-10.4 ppm; Ca, 69.8+/-14.0 for 45S5; Si, 33.4+/-3.8 ppm; Ca, 57.1+/-2.8 ppm for 6P53-b) compared with the control extract (Si<0.1 ppm, Ca 49.0 ppm in alpha-MEM) (ANOVA, p<0.05). Cell proliferation rate was enhanced (1.5x control) within the first 3 days after adding 45S5 and 6P53-b GCM. MC3T3-E1 subclone 4 cultures were then studied for their response to the addition of test media (GCM and control medium along with ascorbic acid (AA; 50 ppm)). Each GCM+AA treatment enhanced collagen type 1 synthesis as observed in both gene expression results (day 1, Col1alpha1, 45S5 GCM+AA: 3x control+AA; 6P53-b GCM+AA: 4x control+AA; day 5, Col1alpha2, 45S5 GCM+AA: 3.15x control+AA; 6P53-b GCM+AA: 2.35x control+AA) and in histological studies (Picrosirius stain) throughout the time course of early differentiation. Continued addition of each GCM and AA treatment led to enhanced expression of alkaline phosphatase (1.4x control+AA after 5 days, 2x control+AA after 10 days), Runx2 (2x control+AA after 7 days) and osteocalcin gene (day 3, 45S5 GCM+AA: 14x control+AA; day 5, 6P53-b GCM+AA: 19x control+AA) and protein expression (40x-70x control+AA after 6 days). These results indicated the enhanced effect of bioactive glass ions on key osteogenic markers important for the bone healing process.
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PMID:Enhanced osteocalcin expression by osteoblast-like cells (MC3T3-E1) exposed to bioactive coating glass (SiO2-CaO-P2O5-MgO-K2O-Na2O system) ions. 1949 91


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