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  • Chemistry  (3)
  • MP-HRP mesoporphyrin IX horseradish peroxidase C  (1)
  • Stark effect  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European biophysics journal 29 (2000), S. 429-438 
    ISSN: 1432-1017
    Schlagwort(e): Key words Horseradish peroxidase ; Spectral hole burning ; Protein isothermal compressibility ; Stark effect ; Porphyrin Q-band splitting ; AbbreviationsHRPC isozyme C of horseradish peroxidase ; MP mesoporphyrin IX ; MP-HRP mesoporphyrin IX horseradish peroxidase C ; MgMP ; Mg(II)-mesoporphyrin IX ; MgMP-HRP Mg(II)-mesoporphyrin IX horseradish peroxidase C ; NHA 2-naphthohydroxamic acid ; SHB spectral hole burning
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract To clarify the role of metal ion coordination in horseradish peroxidase C (HRPC), the effect of pressure and of an externally applied electric field on spectral holes was compared for both metal-free and Mg-mesoporphyrin-substituted horseradish peroxidase C (MP-HRP and MgMP-HRP), as affected by the binding of 2-naphthohydroxamic acid (NHA). The data are compared to earlier studies performed on the same derivatives. Results obtained for MP-HRP show the presence of a predominant MP tautomer, as well as that of another small population with different pocket field and isothermal compressibility (0.12 vs 0.24 GPa−1). Binding NHA induces the formation of two new almost equal populations of MP-HRP tautomer complexes and the protein compressibility in both forms is increased to 0.50 and 0.36 GPa−1. The protein structure becomes much softer than in the absence of NHA. Binding the same substrate to MgMP-HRP resulted in MgMP adopting a single conformation with no compressibility changes, while without NHA, two forms were possible. Stark effect results show charge rearrangement upon substrate binding in both cases. We propose that it is the presence of the metal that stabilizes the structure during the reorganization of the protein matrix induced by the substrate binding event. With the metal, only one conformation is adopted, without significant structural rearrangement but with charge redistribution. The dissociation constants determined for NHA binding to both derivatives and to native HRPC show that studies using mesoporphyrin and Mg-mesoporphyrin derivatives are relevant to investigating the specificity of the substrate-binding pocket in this enzyme.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 447-457 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The surface characteristics of sixteen “monobloc” titanium-6% aluminum-4% vanadium (Ti6Al4V) femoral components (two of the 6-Ti-28 type and 14 of the 6-Ti-32 type) retrieved after periods of 78-131 months following loosening of the femoral component, as well as two unimplanted controls, were studied. The femoral heads were examined by a combination of noncontact light profilometry, scanning electron microscopy, and energy-dispersive X-ray analysis. No consistent correlations were found between classical surface roughness parameters (average, root mean square, peak-to-valley roughness, and radius of curvature) and any clinical parameter studied (patient gender, weight, and height; primary diagnosis; implantation time; or calculated force applied on the hip joint). This extensive quantitative topographic analysis suggests that wear mechanisms in vivo are complex and that wear of titanium alloy femoral heads is partly attributed to a combination of an imperfect nature of the surface before implantation, removal of the oxide layer causing abrasion of the alloy, subsequent deformation of the bearing surface including polishing, and, to a very small degree, patient parameters. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 959-971 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The objective of this project was to characterize soft tissue bonding to porous coated implants such as those that would be used for resection-reconstruction of osteosarcoma cases. We were interested in determining conditions which would provide both mechanical attachment of the implant to the surrounding tissue and produce a vascularized interface. In a bilateral canine implant model, both femoral midshafts were replaced with a porous coated cobalt-chrome segmental implant fabricated with average pore sizes of 300 μm or 900 μm. Twelve implants, six of each pore size, were used in six dogs. Two dogs were sacrificed at 2, 4, and 6 months after implantation. The soft tissue-implant interface was characterized mechanically with peel tests and histologically using light microscopy and immunohistochemistry. At all periods, a nonvascularized fibrous membrane surrounded the smaller pore size implants, without ingrowth or mechanical bonding. In contrast, a vascularized membrane developed within and around the larger pore size implants; the attachment strength increasing with implantation time. The vascularity increased in size and quantity with time. This study demonstrates the feasibility of obtaining vascularized soft tissue attachment to tumor replacement implants with appropriate porous coated implant design.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 839-850 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The effects of microstructure and wettability of porous high density polyethylene (HDPE) substrates on chondrocyte collagen synthesis in vitro were assayed. Three size grades of hydrophilic and hydrophobic HDPE substrates with ranges of pore volumes of 40-60%, pore sizes of 115-335 μm, and surface areas per unit volumes of 7-20 mm2/mm3 were seeded with fetal bovine chondrocytes. After 7 days of incubation, the cells within all substrates remained spherical, and contained mainly type II collagen (as verified by type I and II collagen I-ELISAs). After 21 days, the majority of cells had spread; however, the matrices still contained mainly type II collagen. The hydrophilic matrices contained significantly more type II collagen than the hydrophobic matrices at both 7 and 21 days, whereas the amount of type II collagen was not influenced by the pore attributes. A significantly higher percentage of type II collagen was also observed in all seeded porous substrates as compared with seeded polystyrene culture dishes, perhaps indicating that the three-dimensional particular nature of the HDPE matrices enhanced the maintenance of phenotypically differentiated chondrocytes and entrapment of their extracellular matrix products. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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