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  • 1
    Electronic Resource
    Electronic Resource
    In vitro biocompatibility of EPM and EPDM rubbers (1997)
    Springer
    Journal of materials science 8 (1997), S. 5-9 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The in vitro toxicity of two EPDM rubbers (K 778 and K 4802) and one EPM rubber (K 740) was tested using human fibroblasts. The modulus of elasticity of each rubber was varied by exposure to different amounts of electron-beam radiation (0, 5 and 10 Mrad). The short-term in vitro toxicity was tested by culturing cells on polymer films. The long-term effect of ageing was simulated by growing fibroblasts in nutrient media prepared from extracts of heat-exposed materials. Cell cultures were studied both quantitatively and (ultra) structurally. Growth curves obtained in the toxicity test did not differ significantly from control values at any day of observation, and also showed that electron-beam radiation did not alter the biocompatibility. The same results were found for all but one material in the artificial ageing test. The number of cells in the K4802/10 Mrad extraction medium was decreased. Ultrastructurally no gross deviations from normal morphology were observed, either in the direct contact test or in the artificial ageing test. The most characteristic feature was a somewhat dilated endoplasmic reticulum. In summary, the in vitro biocompatibility of EPDM-rubbers as observed in this study is satisfactory and motivates further investigation of their biocompatibility in animal experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018577910511
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  • 2
    Electronic Resource
    Electronic Resource
    Polyacids as bonding agents in hydroxyapatite polyester-ether (PolyactiveTM 30/70) composites (1998)
    Springer
    Journal of materials science 9 (1998), S. 23-30 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A previously developed method to improve the interface between hydroxyapatite (HA) and a polyester-ether (PolyactiveTM 70/30) by using polyacrylic acid or poly(ethylene-co-maleic acid) has been applied to HA/PolyactiveTM 30/70 composites noting that polyactiveTM 30/70 contains less polyethylene glycol (PEG) segments and a higher concentration of rigid poly(butylene terephthalate) (PBT) segments. The mobility of the PEG segments is significantly affected by the existence of a high concentration of rigid PBT segments. Our experimental results show that this method is indeed suitable for making HA/PolyactiveTM 30/70 composites. The hydrogen bond/dipole interaction forming ability of the PEG segment is not affected by the existence of relatively large amounts of PBT segments. By using these coupling agents, the mechanical properties of the composite can be significantly improved both in dry and wet states. A fractographical study of the fracture surfaces revealed that the surface modified HA particles maintain better contact at fracture. It also showed that larger HA particles may initiate cracks and that such particles may be responsible for a decrease in the tensile strength of the composites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008826410395
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of copolymers of polyethylene oxide and polybutylene terephthalate (polyactive): mechanical behaviour (1998)
    Springer
    Journal of materials science 9 (1998), S. 375-379 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Polyether–polyester segmented block copolymers (Polyactive®) on the basis of polybutylene terephthalate (PBT) and polyethylene oxide (PEO) were mechanically tested. Tensile strength and modulus of elasticity in compressive and tensile deformation were recorded according to ASTM standards. These tests were done in vitro under dry and wet conditions, and after 3, 9 and 25 wk subcutaneous implantation of these materials in goats. Strength and modulus of elasticity were higher with increased contents of PBT in the copolymers. After water uptake, the polymer displayed a lower strength and stiffness. Disintegration of the materials with 70% PEO content and dumb-bell shape was noted at 3 wk. Disintegration of the cylinders of the same material was seen after 25 wk implantation. Of the materials with 60% PEO content, only four of the five dumb-bells had disintegrated after 25 wk implantation. The in vivo test results of all other implants did not show a clinically relevant decrease of strength and stiffness with time after implantation of the copolymers in the goats. Mechanical behavior of the various copolymers seemed mainly determined by the amount and integrity of the PBT phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1013227428530
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  • 4
    Electronic Resource
    Electronic Resource
    The polymer PolyactiveTM as a bone-filling substance: an experimental study in rabbits (1998)
    Springer
    Journal of materials science 9 (1998), S. 449-455 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The biocompatible, osteoconductive and resorbable polymer PolyactiveTM (PA) was investigated for its performance as a bone-graft substitute. The model consisted of a 4 mm borehole, 1.5 cm distal of the major trochanter in both femurs of a rabbit, of which one was filled with a cylinder of porous PA. The other was left untreated. PA70/30 and PA60/40 were investigated, both before and after being incubated with allogenic bone marrow. Analyses were performed after 4, 8, 26 and 52 weeks and comprised dual energy X-ray absorptiometry (DXA) and image analysis of histological sections. DXA revealed an increased bone mineral density in the filled defects compared to the controls, both at the defect and immediately proximal and distal of the defect. Histology showed that gap-bridging had occurred within 8 weeks, with 80%–90% of the pores of PA70/30 and PA60/40 occupied by new bone, and an intimate bone–PA contact. PA70/30 seemed to be more suitable compared to PA60/40, in that the highest amount of bone was formed within the shortest period of time. Incubation of PA with allogenic bone marrow resulted in inflammatory reactions at the sites of implantation, which delayed bone growth, but did not prevent it. It was concluded that PA70/30 and PA60/40 are suitable bone-graft substitutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008867300634
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  • 5
    Electronic Resource
    Electronic Resource
    In vivo bone formation by human bone marrow cells: effect of osteogenic culture supplements and cell densities (1998)
    Springer
    Journal of materials science 9 (1998), S. 855-858 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Bone marrow is known to contain a population of osteoprogenitor cells that can go through complete differentiation when cultured in a medium containing appropriate bioactive factors. In this study, porous particles of a calcium phosphate material were seeded with adult human bone marrow cells in the second passage. After an additional culture period of 1 wk in the particles, these hybrid constructs were subcutaneouslly implanted in nude mice with a survival period of 4 wk. The cell seeding densities range from 0–200 000 cells per particle and the cell culture system was designed to investigate the single and combined effects of dexamethasone and recombinant human bone morphogenetic protein 2 (rhBMP-2). The hybrid “material/tissue” constructs were processed for histology and the amount of de novo bone formation was quantified, for each culture condition, by histomorphometric techniques. The relative percentage of mineralized bone formation reached a maximal value of 19.77±5.06, for samples cultured in the presence of rhBMP-2 and with a seeding density of 200 000 cells/particle, compared to 0.52±0.45 for samples in which no cells had been cultured and had been incubated in culture medium supplemented with Dex and rhBMP-2. For the tested conditions and for the low cell numbers used in this study, rhBMP-2 proved to be an essential bioactive factor to obtain in vivo bone formation by our culture system. The results from this study prove the potential of cultured adult human bone marrow cells to initiate and accelerate de novo bone formation after transplantation into an ectopic site. © 1998 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008904413859
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  • 6
    Electronic Resource
    Electronic Resource
    Bone tissue engineering on calcium phosphate-coated titanium plates utilizing cultured rat bone marrow cells: a preliminary study (1998)
    Springer
    Journal of materials science 9 (1998), S. 859-863 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The use of osteoinductive in vitro tissue-coated implants in orthopaedic and dental surgery (e.g. revision hip arthroplasty), could result in a better fixation of these implants. However, this tissue engineering technology has only proved to be effective in porous materials and not on flat implant surfaces. In this study we have demonstrated that calcium phosphate-coated titanium plates with a layer of cultured osteogenic cells and their extracellular matrix can initiate bone formation in vivo. Both primary and subcultured rat bone marrow cells were grown on to biomimetic calcium phosphate-coated titanium plates. After 7 d of culture, in the presence or absence of dexamethasone, the implants were subcutaneously implanted in nude mice for 4 wk. Control samples, which consisted of calcium phosphate-coated plates without cultured cells and porous calcium phosphate particles with or without cultured cells, were also implanted subcutaneously. At autopsy, no bone formation could be detected on any of the control samples without cells and samples with subcultured cells, which were primary cultured in medium without dexamethasone. In contrast, clear de novo bone formation could be observed on the calcium phosphate-coated plates and in the porous calcium phosphate particles with primary or subcultured cells, which had been continuously cultured in medium with dexamethasone. These results indicate that this hybrid technology offers great potential for the fixation of flat bone replacement implants (e.g. artificial hips) in inferior bone in the future. © 1998 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008956430697
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  • 7
    Electronic Resource
    Electronic Resource
    Editorial (1998)
    Springer
    Journal of materials science 9 (1998), S. 673-674 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008991711616
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation of Calcium Phosphate Coating on Porous Tantalum (1998)
    Springer
    Journal of materials science 17 (1998), S. 925-930 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026404404483
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  • 9
    Electronic Resource
    Electronic Resource
    The biological performance of calcium phosphate ceramics in an infected implantation site III: Biological performance of β-whitlockite in the noninfected and infected rat middle ear (1986)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 1197-1217 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biological performance of macroporous β-whitlockite implanted in the rat middle ear was evaluated. The material was studied in the non-infected middle ear and in middle ears infected by Staphylococcus aureus. β-whitlockite was quickly covered by a normal mucosa. One week post-operatively the macropores were filled with exudate, fibrous tissue, and a small quantity of bone. Six months after the operation the greater part of the macropore area was filled with bone (74%); fibrous tissue accounted for 20%, and exudate for 5%. In histological sections, the macropore area of β-whitlockite had increased by 68% after six months, indicating biodegradation. Macrophages and multinucleated cells were present in the vicinity of the implant and played a role in this biodegradation. Besides cytoplasmic vacuoles containing calcium phosphate, the cells showed smaller granules containing trace elements originally present in the implant material, such as silicon, titanium, aluminum, iron, and magnesium.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820200810
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  • 10
    Electronic Resource
    Electronic Resource
    Biocompatibility of six elastomers in vitro (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 423-439 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biocompatibility of two silicone rubbers, Silastic and Dow Corning Elastomer, and of a polyether and a polyester urethane, a polyether polyester copolymer, and polypropylene oxide was assessed in vitro. These elastomers were selected for assessment as a possible alloplastic tympanic membrane. For these studies use was made of rat middle ear mucosa explants and serially cultured epithelium. The quantitative results were based on epithelial growth curves, the morphological picture was based on the findings in epithelium, and the aging of a biomaterial was simulated. Epithelium morphology was investigated by scanning and transmission electron microscopy and x-ray microanalysis. Quantitative results showed that on Dow Corning Elastomer and polypropylene oxide, cell proliferation was significantly lower compared to normal growth curves. The morphological findings were negative for polypropylene oxide, and did not discriminate between the other biomaterials under study. The simulation results indicated better biocompatibility for the polyurethanes and the polyether polyester copolymer compared with that of polypropylene oxide and both silicone rubbers. Under the simulation conditions, cells exposed to Silastic showed siliconcontaining inclusions. These in vitro results suggest that the biocompatibility of the polyurethanes and the polyether polyester copolymer is better than that of both silicone rubbers and polypropylene oxide.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820220506
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