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  • 1
    ISSN: 0021-9304
    Keywords: implant ; titanium ; osteoblasts ; prostaglandin ; indomethacin ; surface roughness ; 1α,25-(OH)2D3 ; differentiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surface roughness affects proliferation, differentiation (alkaline phosphatase and osteocalcin), local factor production [transforming growth factor (TGFβ) and prostaglandin E2 (PGE2)], and response to 1,25-(OH)2D3 (1,25) of MG63 osteoblast-like cells. In this study, we examined whether the effect of surface roughness on MG63 cells is mediated by prostaglandins produced by the cells. Unalloyed titanium (Ti) disks were pretreated with HF/HNO3 (PT) and then machined and acid-etched (MA). Disks were also coarse grit-sandblasted (SB), coarse grit-sandblasted and acid-etched (CA), or plasma-sprayed with Ti particles (PS). The surfaces, from smoothest to roughest, were PT, MA, CA, SB, and PS. MG63 cells were cultured to confluence on the Ti disks in the presence or absence of 10-7M indomethacin (Indo), a specific inhibitor of cyclooxygenase activity, resulting in decreased prostaglandin production. When the cells reached confluence, cell number, cell layer alkaline phosphatase specific activity (ALPase), and osteocalcin (OC) and latent TGFβ (LTGFβ) production were determined. In addition, confluent cultures which had been grown in the absence of Indo were exposed to 10-7M 1,25, 10-7M Indo, or a combination of the two for 24 h. On the rougher surfaces, cell number was decreased and ALPase, OC, and LTGFβ were increased. When indomethacin was present throughout the culture period, the effect of surface roughness on cell number, OC, and LTGFβ was abolished. ALPase was reduced, but surface roughness-dependent effects were still observed. Addition of indomethacin to confluent cultures for 24 h had no effect on any of the parameters examined, with one exception: Cells cultured on MA surfaces exhibited a more differentiated phenotype. 1,25 increased all parameters examined on SB, CA, and PS surfaces. When indomethacin was added with 1,25, the 1,25-dependent effects on cell number and OC and LTGFβ production were abolished; however, ALPase was unaffected. This indicates that bone cell response to systemic hormones may be modified by implant surface roughness. This effect may be mediated, at least in part, by prostaglandins produced by the same cells. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 489-496, 1998.
    Additional Material: 8 Ill.
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  • 2
    ISSN: 1435-1803
    Keywords: Ischemic preconditioning ; rabbit ventricular myocytes ; HEK 293 cell line ; HIT-T15 cell line ; C2C12 cell line ; differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated whether preconditioning could protect several cultured cell lines, to determine whether the protection is specific for cells derived from different myogenic and non-myogenic sources. Ischemia was simulated by centrifugation of cells into a pellet, and cell viability was determined by hypotonic trypan blue solution. Preconditioning was produced by brief exposures to either glucose-free solution or metabolic inhibition. Freshly isolated rabbit ventricular myocytes were studied to confirm that preconditioning occurs in this model. We then compared these results to those in several cultured cell lines, including HEK 293 cells derived from human embryonic kidney, HIT-T15 cells from Syrian hamster pancreatic islets, and C2C12 cells from mouse skeletal muscle. In the latter cell line, we also determined whether differentiation alters preconditioning. Preconditioning protected rabbit ventricular myocytes: the percentage of dead cells was decreased from 36.8±4.7% in the control group to 23.0±5.2% in the preconditioned group after 60 min and from 50.7±2.1% in the control group to 25.5±4.5% in the preconditioned group after 120 min ischemia (p〈0.02). In contrast, there was no protection from preconditioning in HEK 293 cells or HIT-T15 cells. Preconditioning did not protect C2C12 myoblasts either. Interestingly, after C2C12 myoblasts had differentiated into myotubes (induced by exposing the cells to low-serum medium), they could then be protected by preconditioning (46.3±3.6% in the control group vs 26.0±2.7% in the preconditioned group after 60 min and 67.4±3.6% in the control group vs 46.0±4.6% in the preconditioned group after 120 min ischemia; p〈0.05). In conclusion, protection from preconditioning is cell-type specific. The presence of endogenous KATP channels (which are plentiful in HIT-T15 cells) is insufficient to enable preconditioning of the cell. Among the various cell types studied, only differentiated muscle cells (rabbit ventricular myocytes and C2C12 myotubes) exhibited preconditioning.
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  • 3
    ISSN: 0021-9304
    Keywords: implant ; titanium ; osteoblasts ; surface roughness ; 1α,25- (OH)2D3 ; differentiation ; local factor ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surface roughness has been shown to affect differentiation and local factor production of MG63 osteoblast-like cells. This study examined whether surface roughness alters cellular response to circulating hormones such as 1α,25-(OH)2D3. Unalloyed titanium (Ti) disks were pretreated with HF/HNO3 (PT) and then were machined and acid-etched (MA). Ti disks also were sandblasted (SB), sandblasted and acid etched (CA), or plasma sprayed with Ti particles (PS). The surfaces, from smoothest to roughest, were: PT, MA, CA, SB, and PS. MG63 cells were cultured to confluence on standard tissue culture polystyrene (plastic) or the Ti surfaces and then treated for 24 h with either 10-8M or 10-7M 1α,25-(OH)2D3 or vehicle (control). Cellular response was measured by assaying cell number, cell layer alkaline phosphatase specific-activity, and the production of osteocalcin, latent (L) TGFβ, and PGE2. Alkaline phosphatase activity was affected by surface roughness; as the surface became rougher, the cells showed a significant increase in alkaline phosphatase activity. Addition of 1α,25-(OH)2D3 to the cultures caused a dose-dependent stimulation of alkaline phosphatase activity that was synergistic with the effect caused by surface roughness alone. 1α,25-(OH)2D3 also caused a synergistic increase in osteocalcin production as well as local factor (LTGFβ and PGE2) production on the rougher CA, SB, and PS surfaces, but it had no effect on the production on smooth surfaces. The inhibitory effect of surface roughness on cell number was not affected by 1α,25-(OH)2D3 except on the SB surface. 1α,25-(OH)2D3 decreased cell number, increased alkaline phosphatase activity and osteocalcin production, and had no effect on LTGFβ or PGE2 production by MG63 cells grown on tissue culture polystyrene. These data suggest that bone cell response to systemic hormones is modified by surface roughness and that surface roughness increases the responsiveness of MG63 cells to 1α,25-(OH)2D3. They also suggest that the endocrine system is actively involved in normal bone healing around implants. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 77-85, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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