ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Mechanism of Consolidation of a Porous-Surfaced Ti–6Al–4V Implant Formed by Electrodischarge Compaction (1999)
    Springer
    Journal of materials science 18 (1999), S. 817-818 
    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:1006653503849
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Surface characteristics of a porous-surfaced Ti-6Al-4V implant fabricated by electro-discharge-compaction (2000)
    Springer
    Journal of materials science 35 (2000), S. 593-598 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Electro-discharge-compaction (EDC) is a unique method for producing porous-surfaced metallic implants. The objective of the present studies was to examine the surface characteristics of the Ti-6Al-4V implants formed by EDC. Porous-surfaced Ti-6Al-4V implants were produced by employing EDC using 480 μF capacitance and 1.5 kJ input energy. X-ray photoelectron spectroscopy was used to study the surface characteristics of the implant materials. C, O, and Ti were the main constituents, with smaller amounts of Al and V. EDC Ti-6Al-4V also contained N. Titanium was present mainly in the forms of mixed oxides and small amounts of nitride and carbide were observed. Al was present in the form of aluminum oxide, while V in the implant surface did not contribute to the formation of the surface oxide film. The surface of conventionally prepared Ti-6Al-4V primarily consists of TiO2, whereas, the surface of the EDC-fabricated Ti-6Al-4V consists of complex Ti and Al oxides as well as small amounts of titanium carbide and nitride components. However, preliminary studies indicated that the implant was biocompatible and supports rapid osseointegration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004768125476
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effect of metal ions on the formation and function of osteoclastic cells in vitro (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 265-271 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To determine if metal ions play a contributing role in loosening of orthopedic implants, the present work investigated whether sublethal concentrations of ions affect the formation and function of osteoclasts in vitro. Rat bone marrow cells were cultured on slices of devitalized bone and in the presence of ions associated with Co-Cr-Mo and Ti-6Al-4V alloys for up to four weeks. Cultures were assayed for total intracellular protein, used as measure of cell growth, and resorption activity of osteoclastic cells derived from hematopoietic stem cells was quantified using image analysis. Although Co2+ caused delayed toxicity not previously observed during short-term experiments, none of the other ions affected cell proliferation, indicating that the chosen concentrations were sublethal. In general, exposure of bone marrow cultures to ions caused either a decrease or no change in the total area of bone resorption. A decrease in the number of resorption pits formed by osteoclastic cells was primarily responsible for the decrease in total amount of resorption. Therefore, even though cells continued to grow over the entire culture period, less osteoclastic activity was observed. Findings indicate that if metal ions play a role in periprosthetic pathology, they may contribute to implant failure by impairing bone repair while allowing fibrous tissue formation following debris-induced osteolysis. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    In vitro cellular responses to bioerodible particles loaded with recombinant human bone morphogenetic protein-2 (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 104-110 
    Details
    ISSN: 0021-9304
    Keywords: bone morphogenetic protein ; osteoblasts ; microspheres ; poly(d,l lactide-co-glycolide) ; cellular responses ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous 50:50 poly(d,l lactide-co-glycolide) microspheres containing varying amounts of “free” recombinant human bone morphogenetic protein-2 (rhBMP-2) were evaluated for their ability to induce/enhance expression of osteoblastic characteristics by pluripotent mesenchymal cells in vitro. “Free” protein (Fp) is defined as protein present on the surface and within the porous matrix of the microspheres. Four preparations of bioerodible particles (BEP) were used: blank - without rhBMP-2; low Fp - 24 μg of free rhBMP-2 per g of particles; medium Fp - 403 μg/g; and high Fp - 884 μg/g. C3H10T1/2 cells (C3H) and bone marrow stromal cells (BMC) were cultured with 1 mg of BEP for up to 4 weeks, and cell growth and expression of osteogenic responses were determined weekly. For both cell types, control cultures (neither BEP nor rhBMP-2) and cultures with blank BEP exhibited no or minimal osteoblastic characteristics. Compared to control and blank BEP cultures, C3H cells responded to particles having medium and high amounts of free rhBMP-2 with increased cell growth and alkaline phosphatase activity, but osteocalcin secretion and mineralization were not markedly influenced. Low Fp BEP enhanced only the alkaline phosphatase activity of C3H cells. In contrast, although growth was not affected, rhBMP-2-loaded BEP increased alkaline phosphatase activity, osteocalcin secretion, and mineralization in BMC cultures in a dose-dependent manner (i.e., blank 〈 low 〈 medium 〈 high Fp). © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 104-110, 1998.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Use of p-nitrophenyl chloroformate chemistry to immobilize protein on orthopedic biomaterials (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 203-208 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biochemical surface modification involves covalently immobilizing biomolecules onto biomaterial surfaces to induce specific biological responses. This approach may be useful for enhancing the fixation of orthopedic implants. p-Nitrophenyl chloroformate (p-NPC) was used to immobilize protein on bulk samples of Co-Cr-Mo and Ti-6Al-4V. Activation of both materials was dependent on the concentration of p-NPC, with a maximum of approximately 1.5 active groups/nm2 of nominal surface area. Trypsin was used as a model protein because much is known about its structure and mode of action. Derivatization with 0.65 mg p-NPC/cm2 resulted in significantly greater enzymatic activity (7.4 BAEE [N-(α)-benzoyl-L-arginine ethyl ester hydrochloride] units) on the Co-Cr-Mo samples compared with higher concentrations of p-NPC (5 BAEE units) and with simple adsorption of trypsin (1.5 BAEE units). An activity of 10.5 BAEE units was measured on both adsorbed and p-NPC-activated Ti-6Al-4V, with the exception of samples derivatized with 1.95 mg p-NPC/cm2, on which activity was significantly lower (4 BAEE units). In probing the linkages between trypsin and biomaterial by treatment with chaotropic agents, guanidine hydrochloride (GuHCl) was observed to eliminate more enzymatic activity than was urea. On Co-Cr-Mo samples, GuHCl removed nearly all the trypsin activity, while urea significantly decreased the activity only at a concentration of 0.65 mg p-NPC/cm2. Treatment of Ti-6Al-4V samples with GuHCl caused a trend of decreasing activity with increasing concentration of p-NPC, whereas urea had no effect on immobilized trypsin activity. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Formation of focal contacts by osteoblasts cultured on orthopedic biomaterials (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 291-301 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The nature of the contact sites formed during the adhesion of osteoblasts to orthopedic implant materials was investigated by fluorescence microscopy. More specifically, the cytoskeletal organization of and the focal contact formation by neonatal rat calvarial osteoblasts attaching to and spreading on 316L stainless steel, Ti-6A1- 4V, Co-Cr-Mo, Synamel (hydroxyapatite), alumina, and borosilicate glass were examined. Focal contacts are regions where the plasma membrane approaches the substrate to within 10-15 nm and where bundles of cytoskeletal microfilaments terminate. Fluorescent-labeling of F-actin- containing microfilaments demonstrated a typical sequence of events as rounded, suspended osteoblasts spread onto the substrates. Immunofluorescent-labeling of the protein vinculin, which is found at the cytoplasmic face of focal contacts, initially showed the formation of streak-like focal patches. On the biomaterials, the vinculin staining subsequently extended up and along, but ventral to, the microfilament bundles. The fibrillar patterns observed at later times may evidence the formation of extracellular matrix contacts.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Activity of enzyme immobilized on silanized Co-Cr-Mo (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 951-957 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The surface of an orthopedic biomaterial was modified by the covalent immobilization of biomolecules. Derivatization of Co-Cr-Mo samples with organic and aqueous solutions of γ-aminopropyltriethoxysilane (APS) resulted in a concentration-dependent number of reactive NH2 groups on the surface available for coupling to protein. The enzyme trypsin was used as a model biomolecule to investigate the effect of immobilization on proteolytic activity. Trypsin was coupled to the silanized samples by formation of Schiff's base linkages via glutaraldehyde. The nature of the interaction between trypsin and biomaterial was then probed by treatment with concentrated guanidine hydrochloride (Gu-HCl) and urea. Residual activity (following treatment with chaotropic agents) of trypsin immobilized on silanized Co-Cr-Mo was dependent both on the nature of the silane solution and on the type of chaotropic agent. Organic silanization with APS required a miniumum density of approximately 49 NH2 per nm2 of nominal surface area (〉0.021 M APS) for residual activity of immobilized trypsin. For aqueous silanization, approximately 5.4 NH2/nm2 (0.51 M APS) resulted in maximal residual trypsin activity. Treatment with GuHCl removed more trypsin activity from Co-Cr-Mo samples silanized with organic solutions of APS than did treatment with urea. On the contrary, with aqueous silanization the samples possessed greater residual activity followig treatment with GuHCl than following urea. Compared to simple adsorption with protein onto Co-Cr-Mo, both methods of silanization with APS resulted in superior residual immobilized enzyme activity. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290806
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Retention of enzymatic activity immobilized on silanized Co-Cr-Mo and Ti-6Al-4V (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 37 (1997), S. 222-228 
    Details
    ISSN: 0021-9304
    Keywords: surface modification ; biochemical modification ; protein immobilization ; γ-aminopropyltriethoxysilane ; orthopedic biomaterials ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biochemical surface modification of biomaterials utilizes immobilized biomolecules to induce preferred tissue responses. Operational stability, or retention of biological activity, of biochemically modified biomaterials is a fundamental determinant of their usefulness. The present study investigated retention of enzymatic activity immobilized on silanized Co-Cr-Mo and Ti-6Al-4V. A model enzyme, trypsin, was immobilized on monolayers and multilayers of silane deposited from aqueous or organic solutions of γ-aminopropyltriethoxysilane (APS). Trypsin-conjugated biomaterials were incubated in cell culture medium at 37°C for up to 96 h, and the residual immobilized activity was measured. Retention of bioactivity in physiological saline was dependent on the type of material and on the method of silanization. Activity of enzyme adsorbed on the metals was lost within 24-48 h. Both mono- and multilayers of APS deposited on Co-Cr-Mo by aqueous silanization effectively retained enzymatic activity throughout the 96 h incubation period. The monolayer retained approximately 23% of the activity initially present, and the multilayers retained approximately 50% of the initial activity. Organic silanization of Co-Cr-Mo was marginally effective as it initially slowed the loss of activity. However, all activity was lost by 48-72 h of incubation. Neither organic nor aqueous silanization enhanced retention of enzymatic activity on Ti-6Al-4V. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 37, 222-228, 1997.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...