UNIPROT:A7KAX9 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:A7KAX9 (grit)
1,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endosseous implants initially come into contact with blood. Thus, the nature of the interactions between blood and implanted endosseous implants may influence subsequent bone healing events in the peri-implant healing compartment. We conducted studies to address the following question: Does implant surface microtexture modulate platelet activity? We used commercially pure Ti (cpTi) disks with four different surface finishes: dual acid-etched (DAE), 320 grit (320G) abraded, machined, and p1200 polished cpTi. Surfaces were characterized by scanning electron microscopy (SEM) and optical profilometry. The DAE and 320G surfaces presented more complex microtextures than the machined or polished surfaces. Platelet activities were measured by quantifying platelet adherence, platelet-derived microparticle (MP) formation, and P-selectin expression as function of surface type. Platelet adhesion, measured using a lactate dehydrogenase (LDH) assay. was increased on DAE and 320G surfaces compared to machined and polished surfaces (p < 0.05). M P formation and P-selectin expression, assayed by flow cytometry, also showed increased activation of platelets on DAE and 320G surfaces. Because increased activation of platelets may lead to up-regulation of osteogenic responses during bone healing, these results may explain the enhanced osteoconductivity known to occur with DAE cpTi surfaces in comparison with machined cpTi surfaces.
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PMID:Platelet interactions with titanium: modulation of platelet activity by surface topography. 1151 87

Biomaterials have been shown to be able to influence the growth and differentiation of osteogenic cells cultured on the surface. Although the precise mechanisms by which the materials influence osteogenic cells are unclear, it is possible that the materials manipulate the expression of integrins by the cells. We therefore studied the expression of a number of integrins by rat bone marrow (RBM) cells, after culture on culture polystyrene, on machined and grit-blasted titanium, and on calcium phosphate-coated titanium. Integrin expression was studied by FACS analysis. We found a large variation in the expression of integrins by cells in replicate experiments. After culture on polystyrene for 7 days, cells expressed alpha1, alpha2, alpha3, alpha5, alpha6, beta1, and beta3, although some of the subunits were expressed only occasionally. The cells did not express the alpha4 subunit. After culture of RBM cells for 8 days on coated and noncoated titanium substrates, cells always expressed alpha3, alpha5, alpha6, and beta1. The alpha1 and beta3 subunits were only expressed in some of the experiments. Frequently, the expression of alpha5, alpha6, and beta1 was higher on the coated than on the noncoated titanium substrates. Based on our results, we conclude that the studied materials are capable of influencing the expression of integrins by RBM cells cultured on relevant implant materials.
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PMID:Modulation of integrin expression on rat bone marrow cells by substrates with different surface characteristics. 1220 1

Macrophage cytokine expression significantly affects wound healing. Macrophage secretion of transforming growth factor beta 1 (TGFbeta1) and bone morphogenetic proteins (BMP) may affect osteogenesis at endosseous implant surfaces. The aim of this investigation was to determine the effect of commercially pure titanium (cpTi) substrate topography on adherent macrophage osteogenic and osteoinductive cytokine expression. J774A.1 murine macrophage cell adhesion was examined by scanning electron microscopy, 0-72 h following plating onto polished, machined, and grit-blasted cpTi surfaces. TGFbeta1 and BMP-2 gene expression by adherent macrophages was determined by the reverse transcription polymerase chain reaction. Macrophage adhesion increased with time on all surfaces and spreading increased with increasing surface roughness (polished < machined < grit-blasted). BMP-2 expression was not evident for cells adherent to polished cpTi at 24 h. In contrast, BMP-2 expression occurred at 24 h in cells adherent to machined and grit-blasted cpTi. BMP-2 expression was evident on all surfaces at 72 h and was greatest in grit-blasted titanium adherent cells. Increasing concentrations of cytochalasin B (0-50 microM) inhibited macrophage spreading and reduced BMP-2 mRNA expression, suggesting a relationship between cell shape and BMP-2 expression. This was further characterized using anti-beta1 and anti-beta3 integrin antibodies. The anti-beta1 integrin antibodies inhibited adherent macrophage BMP-2 mRNA expression. Anti-beta3 integrin antibody treatment only modestly reduced BMP-2 mRNA expression. Endosseous implant surface topography induced changes in macrophage shape that were associated with changes in BMP-2 expression in J774A.1 mouse macrophage cell line. This first demonstration of BMP-2 expression by cpTi adherent macrophages suggests that the macrophage may contribute surface-specific osteoinductive signals during bone formation at implanted alloplastic surfaces.
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PMID:Titanium surface topography alters cell shape and modulates bone morphogenetic protein 2 expression in the J774A.1 macrophage cell line. 1252 6

The objective of this study was to examine the osteoinductive capacity of different concentrations of BMP-2 on bone marrow stromal cells in vitro. Further, we intended to determine whether titanium provided with an increased surface roughness is more efficient in osteoblast differentiation than machined titanium. Therefore, 20,000 cells/ml were seeded and cultured on machined and grit-blasted titanium discs for 4, 8 and 16 days. Different concentrations of rhBMP-2 (0, 10, 100, 1000 ng/ml) were supplemented to the medium for 8 days of culturing. To evaluate cellular proliferation and differentiation, specimens were examined for DNA, alkaline phosphatase activity, and calcium content. Morphological appearance of the specimens at 8 and 16 days of incubation was evaluated using scanning electron microscopy. Two separate experimental runs were performed. Evaluation of the DNA and alkaline phosphatase data revealed that a significant difference existed for these data between both experimental runs. Further analysis of the DNA figures learned that roughening of the titanium surface and addition of BMP-2 had no effect on cell proliferation. The alkaline phosphatase analysis and calcium measurements revealed that BMP-2 stimulated the early differentiation of osteogenic cells on machined titanium substrates in a dose-dependent manner. After 16 days of culture, no significant differences in calcium content could be observed anymore between machined and roughened titanium surfaces. Further, the data revealed that the machined surfaces showed a significant increase in calcium deposition when 100 and 1000 ng/ml BMP-2 were supplemented to the medium. However, the roughened surfaces showed this significant enhancement in calcium content only with 1000 ng/ml BMP-2. In addition, SEM evaluation revealed a dose-dependent response to BMP-2. Increasing BMP-2 concentrations resulted in more calcified globular accretions on bone surfaces than when no BMP-2 was added. On the basis of our results, we conclude that (1) due to the heterogeneous nature of bone marrow, experimental results with primary rat bone marrow cells are difficult to reproduce from one experiment to the other, and (2) addition of rhBMP-2 in the medium stimulates the early differentiation and matrix mineralization of osteogenic cells on machined titanium surfaces in a dose-responsive manner. Further, we concluded that our roughened titanium surfaces had no effect on proliferation and differentiation of primary derived rate bone marrow cells.
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PMID:Observations on the effect of BMP-2 on rat bone marrow cells cultured on titanium substrates of different roughness. 1261 75

Osteoblasts exhibit a more differentiated morphology on surfaces with rough microtopographies. Surface effects are often mediated through integrins that bind the RGD motif in cell attachment proteins. Here, we tested the hypothesis that modulating access to RGD binding sites can modify the response of osteoblasts to surface microtopography. MG63 immature osteoblast-like cells were cultured on smooth (Ti sputter-coated Si wafers) and rough (grit blasted/acid etched) Ti surfaces that were modified with adsorbed monomolecular layers of a comb-like graft copolymer, poly-(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), to limit nonspecific protein adsorption. PLL-g-PEG coatings were functionalized with varying amounts of an integrin-receptor-binding RGD peptide GCRGYGRGDSPG (PLL-g-PEG/PEG-RGD) or a nonbinding RDG control sequence GCRGYGRDGSPG (PLL-g-PEG/PEG-RDG). Response to PLL-g-PEG alone was compared with response to surfaces on which 2-18% of the polymer sidechains were functionalized with the RGD peptide or the RDG peptide. To examine RGD dose-response, peptide surface concentration was varied between 0 and 6.4 pmol/cm(2). In addition, cells were cultured on uncoated Ti or Ti coated with PLL-g-PEG or PLL-g-PEG/PEG-RGD at an RGD surface concentration of 0.7 pmol/cm(2), and free RGDS was added to the media to block integrin binding. Analyses were performed 24 h after cultures had achieved confluence on the tissue culture plastic surface. Cell number was reduced on smooth Ti compared to plastic or glass and further decreased on surfaces coated with PLL-g-PEG or PLL-g-PEG/PEG-RDG, but was restored to control levels when PLL-g-PEG/PEG-RGD was present. Alkaline phosphatase specific activity and osteocalcin levels were increased on PLL-g-PEG alone or PLL-g-PEG/PEG-RDG, but PLL-g-PEG/PEG-RGD reduced the parameters to control levels. On rough Ti surfaces, cell number was reduced to a greater extent than on smooth Ti. PLL-g-PEG coatings reduced alkaline phosphatase and increased osteocalcin in a manner that was synergistic with surface roughness. The RDG peptide did not alter the PLL-g-PEG effect but the RGD peptide restored these markers to their control levels. PLL-g-PEG coatings also increased TGF-beta1 and PGE(2) in conditioned media of cells cultured on smooth or rough Ti; there was a 20x increase on rough Ti coated with PLL-g-PEG. PLL-g-PEG effects were inhibited dose dependently by addition of the RGD peptide to the surface. Free RGDS did not decrease the effect elicited by PLL-g-PEG surfaces. These unexpected results suggest that PLL-g-PEG may have osteogenic properties, perhaps correlated with effects that alter cell attachment and spreading, and promote a more differentiated morphology.
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PMID:RGD-containing peptide GCRGYGRGDSPG reduces enhancement of osteoblast differentiation by poly(L-lysine)-graft-poly(ethylene glycol)-coated titanium surfaces. 1476 25

Three different microstructures were obtained on a titanium surface via immersion in HCl, H3PO4, or mixed acid of HNO3 and HF (HNO3/HF) solution. The microstructure and Rmax of the acid-treated surfaces were dependent on the acid type and immersion conditions. The growth rate of the osteogenic cell line MC3T3-E1 on each acid-treated sample, which was measured using MTT-formazan assay, was significantly higher than that of the standard which was ground with #400 SiC grit paper. Moreover, both the H3PO4 treated sample and the HNO3/HF-treated surface showed a tendency to enhance the alkaline phosphatase activity of MC3T3-E1 cells, which were grown on each acid-treated surface. These results suggest that the acid treatment of titanium is effective for the improvement of its osteocompatibility.
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PMID:Effect of microstructure of titanium surface on the behaviour of osteogenic cell line MC3T3-E1. 1534 15

The aim of this study was to evaluate the osteogenic properties of magnetron sputtered dicalcium pyrophaosphate (DCPP) and hydroxylapatite (HA) coatings. Therefore, DCPP and HA coatings were deposited on grit-blasted titanium discs. The substrates were used as-prepared or received an additional heat treatment which changed the amorphous coating structure to a crystalline structure. Subsequently, rat bone marrow stromal cells were cultured for 1-24 days on the various substrates. DNA and alkaline phosphatase activity was determined after 1, 3, 5, 8, and 12 days of incubation. Osteocalcin expression was evaluated after 8, 12, 16, and 24 days of incubation. Scanning electron microscopical analysis of cell morphology and coating characteristics was done after 8 and 16 days of incubation. All assays were done in duplicate and in each assay all specimens were present in fourfold. Results demonstrated that the cells did not proliferate and differentiate on all amorphous coatings. SEM revealed that the amorphous coatings showed significant dissolution. On the crystalline DCPP and HA coatings an increase in DNA and alkaline phosphatase activity was seen starting at day 8 of incubation. Osteocalcin expression on the crystalline coatings started to increase at day 16 of incubation. SEM showed that the growth and differentiation of the cells was associated with extensive collagen fiber formation and surface mineralization in the form of globular accretions. Further, statistical testing revealed that proliferation and differentiation of the rat bone marrow stromal cells started significantly earlier on the crystalline HA coatings than that on the crystalline DCPP coatings. These results demonstrate that the rat bone marrow stromal cells proliferated and differentiated only on crystalline magnetron sputtered DCPP as well as HA coatings, which warrants the further in vivo analysis of the bone healing supporting properties of these coatings.
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PMID:Growth behavior of rat bone marrow cells on RF magnetron sputtered hydroxyapatite and dicalcium pyrophosphate coatings. 1660 22

During the process of bone formation, titanium (Ti) surface is an important factor in the modulation of osteoblastic function. This study was conducted in order to determine the effects of different Ti surfaces on the biological responses of a human osteoblast-like cell line (MG63). MG63 cells were cultured on smooth (S), sandblasted large-grit and acid etching (SLA), hydroxyapatite (HA), hydroxyfluoride (HF), titanium nitrate (TIN), and diamond-like carbon (DLC) Ti. The morphology of these cells were assessed by SEM. The cDNAs prepared from the total RNAs of the MG63 were hybridized into a human cDNA microarray (1152 elements). The appearances of the surfaces observed by SEM were different on each of the six dental substrate types. The SLA and HA surfaces were determined to be rougher than the others. MG63 cells cultured on SLA and HA exhibited cell-matrix interactions. In the expression of genes involved in osseointegration, several genes, including bone morphogenetic protein, cadherin, integrin, and insulin-like growth factors, were upregulated on the different surfaces. Several genes, including fibroblast growth factor receptor 4, Bcl 2-related protein, and collagen, were downregulated on the different surfaces. The attachment and expression of key osteogenic regulatory genes were enhanced by the surface roughness of the dental materials used.
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PMID:Effect of various implant coatings on biological responses in MG63 using cDNA microarray. 1662 96

The aim of this study was to investigate the influence of hydrophobic acid-etched (A) and coarse-blasted large-grit and acid-etched (SLA) surfaces as well as hydrophilic modified acid-etched (modA) and modified coarse-blasted large-grit and acid-etched (modSLA) surfaces on the behavior of MG63 cells grown on these surfaces through determination of cell attachment and cell proliferation, time-lapse microscopy of fluorescence-labeled cells, and determination of gene expression by reverse transcription-polymerase chain reaction (RT-PCR). No significant difference of cell attachment on various titanium surfaces was found. Increased cell proliferation was observed on the A surface and the SLA surface compared with the modA surface and the modSLA surface. After 2 days of incubation, on modSLA and modA surfaces a tendency of formation of cell clusters has been observed, which was most pronounced on modSLA surface. On the A and the SLA surface, cell cluster formation started after longer incubation periods. The expression level of the bone-associated genes (alkaline phosphatase, osteocalcin, type-I-collagen, osteoprotegerin, and glyceraldehyde-3-phosphate-dehydrogenase) detected by RT-PCR was highest on the modSLA surface. In conclusion it has been demonstrated that the modSLA surface results in an enhanced cluster formation of osteoblasts grown on this surface and in an increased expression of key osteogenic regulatory genes in osteoblasts.
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PMID:The initial attachment and subsequent behavior regulation of osteoblasts by dental implant surface modification. 1732 17

The objective of this study was to characterize the physicochemical, dissolution, and osteogenic properties of radio frequency magnetron sputtered dicalcium pyrophosphate/tricalciumphosphate (Pyro/TCP) and hydroxylapatite (HA) coatings. Therefore Pyro/TCP and HA coatings were deposited on grit-blasted titanium discs. The results showed that the deposited coatings were amorphous and changed into a crystalline structure after IR heat-treatment of 550 degrees C for HA and 650 degrees C for Pyro/TCP. Heat-treated HA coatings appeared to be stable during immersion in simulated body fluid (SBF), that is no changes in the XRD pattern were observed. Also, no dissolution of the coating was observed by scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) revealed that the Ca/P ratio of the HA coatings remained constant during SBF immersion. On the other hand, the heat-treated Pyro/TCP coatings showed a surface reaction of calcium pyrophosphate into a beta-tricalcium phosphate phase during SBF immersion. This was confirmed by EDS analysis. Rat bone marrow-derived osteoblast-like cells cultured on the heat-treated substrates showed that cell proliferation and differentiation occurred on both types of bioceramic coatings. No significant differences for proliferation and early differentiation were observed between cells cultured on heat-treated Pyro/TCP and HA at individual time points. However, osteocalcin expression, a late marker for osteoblast-like cell differentiation, was significantly increased after 12 days of culture on HA-coatings. These results were confirmed by SEM observations and suggest increased osteogenic properties for HA-coatings over Pyro/TCP-coatings. Additional research is necessary to obtain conclusive evidence on the in vivo osteogenic capacity of Pyro/TCP coatings.
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PMID:Characterization and in vitro evaluation of biphasic calcium pyrophosphate-tricalciumphosphate radio frequency magnetron sputter coatings. 1763 19

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