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  • 1
    Electronic Resource
    Electronic Resource
    Diffusion of gases through polyurethane block polymers (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 201-214 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The diffusivities of simple gases through a series of polyurethane block copolymers of differing aromatic urethane content and type of soft segment were measured using a quadrapole mass spectrometer as a detecting device. Although an Arrhenius expression generally described the temperature dependence of diffusion in this system, a discontinuity was observed in the Arrhenius plots for some materials, and the discontinuity was found to be related to the onset of the glass transition in the hard domains. Increasing the hard segment content of the materials decreased the diffusivity due to the increase in the activation energy of diffusion. Increasing the soft segment length brought about a decrease in the activation energy with an increase in diffusivity. Polyster urethanes had lower activation energies for diffusion than polyether urethanes of similar hard segment composition. Finally, as the penetrant diameter was increased, a decrease in the diffusivity and an increase in the activation energy was noted.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230118
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  • 2
    Electronic Resource
    Electronic Resource
    Zeta potential of bone from particle electrophoresis: Solution composition and kinetic effects (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 47-57 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The morphology of bone may be influenced by many factors, including electromechanical ones such as electric potentials, electric fields, or zeta potentials. Stress-generated potential studies in bone and particle electrophoresis studies using calcium-deficient hydroxyapatite have shown that the zeta potential depends on the composition of the steeping fluid and steeping time. To better quantify and understand these in situ potential changes in bovine cortical bone, the effects of alterations in calcium, phosphate, and fluoride concentrations in Neuman's Fluid (NF), which simulates in vivo bone extracellular fluid, were investigated using particle electrophoresis. The zeta potential increased in magnitude with increased calcium concentration in NF in as little as 17 min. Increasing phosphate concentration in NF also increased the zeta potential magnitude. These results provide support for a structural model of the bone matrix surface-bone fluid interface, which incorporates the bone surface proper (composed of collagen, mineral, and boundary regions), stationary layer (in which ions, ionic complexes, and proteins may be adsorbed), and bone extracellular fluid. These results, coupled with those of previous studies, indicate that the protein phase probably has an important role in the determination of the physiologic zeta potential; the role of the mineral phase may also be important. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290108
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  • 3
    Electronic Resource
    Electronic Resource
    Platelet and monoclonal antibody binding to fibrinogen adsorbed on glow-discharge-deposited polymers (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 729-739 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The state of fibrinogen adsorbed on untreated and glow-discharge-treated surfaces was examined by measuring platelet adhesion, monoclonal antibody (mAb) binding, the amount of fibrinogen adsorbed, and the amount of adsorbed fibrinogen which could be eluted with sodium dodecyl sulfate (SDS). Tetrafluoroethylene (TFE) glow-discharge-treated polymers have a lower surface free energy (in air) and retain a larger fraction of adsorbed fibrinogen than untreated surfaces after SDS elution. Platelet adhesion was lowest on the TFE-treated surfaces which retain the highest amounts of fibrinogen after SDS elution. Fibrinogen may undergo unfolding or spreading on the TFE-treated surfaces to minimize interfacial free energy (in water) and maximize protein-;surface interactions. When it is adsorbed on the TFE-treated surfaces, fibrinogen evidently assumes a state which somehow prevents its recognition and binding by platelet receptors. Monoclonal antibodies that bind to the three regions in fibrinogen thought to be involved in platelet adhesion were therefore used to detect changes in adsorbed fibrinogen. These regions and the antibodies which bind to them are: the COOH-terminal of the γ-chain, mAb M1; the RGD peptide sequence at Aα 95-98, mAb R1; the RDG sequence at Aα 572-575, mAb R2. For fibrinogen adsorbed on the untreated or TFE-treated surfaces, M1 and R2 binding was relatively high compared to background, while R1 binding was low. However, the amount of binding of each mAb to fibrinogen adsorbed on the TFE-treated surfaces was equal to or greater than fibrinogen adsorbed to the untreated surfaces. Therefore, antibody-detectable changes in the platelet binding regions of adsorbed fibrinogen that might have been caused by conformational or orientational rearrangements were not observed for the TFE-treated surfaces. The data suggest that the tight binding of fibrinogen on a surface may directly affect the ability of the fibrinogen to interact with the platelet receptors - i.e., that fibrinogen must be loosely held to facilitate maximal interaction with platelet receptors. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290609
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of antibiotic additions on the mechanical properties of acrylic cement (1978)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 12 (1978), S. 473-490 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Early work on hip prosthesis showed that the metal component would loosen in bone even when screws were used. This practice resulted in the death and resorption of the bone; thus cement was used in orthopedic surgery for firm implantation of prostheses. In recent years antibiotics have been added to the cement as a prophylaxis against infection.This research investigates the effects of antibiotics on the diametral tensile and compression strength of the cement. Samples made with 2 g of antibiotic per surgical packet of bone cement containing the antibiotics gentamicin, keflin, and a combination of the two were tested. These samples were aged at ambient temperature for periods of 1 day and 1, 2, 8, 13, and over 30 weeks.A statistical analysis using a two-way analysis of variance with interaction was conducted. It was concluded that the compression strength was affected by the antibiotic, and not by the aging period, but that there is an antibiotic-aging period interaction. The tensile strength is not affected by either the antibiotic or the aging period, and there is an antibiotic-aging period interaction. Current work being conducted will analyze additional factors and interactions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820120403
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  • 5
    Electronic Resource
    Electronic Resource
    Fracture characteristics of acrylic bone cements. I. Fracture toughness (1976)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 10 (1976), S. 805-828 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The vital first phase of the overall materials study to protract the life of the total joint replacements is the identification of the fracture toughness and fatigue properties of bone cements. Information gained from fatigue testing, performed in a manner which simulates in vivo conditions, and fracture toughness, which is a measure of the propensity of a crack to propagate, is the first step towards the prediction of the life of the total joint replacement. This study is concerned with the fracture toughness of Zimmer and Simplex-P cold-curing bone cements.Following cement fabrication conditions which closely approximate clinical procedures, fracture toughness testing was conducted on cement specimens which were immersed in bovine serum at 37°C in order to simulate in vivo conditions. In addition, a similar study was completed on specimens, tested in air at ambient temperature for purposes of comparison. Results of this procedure, when analyzed by a Student's t-test at the 95% confidence level with eight degrees of freedom, indicate that both Zimmer and Simplex-P exhibit a higher fracture toughness in the simulated physiological environment.In order to determine whether the addition of barium sulfate to these cements compromises the fracture toughness, the above described testing rationale was repeated, indicating the existence of a complicated relationship between the different testing environments and barium sulfate. The importance of these results lies in the fact that an increased fracture toughness indicates that a cement will inherently exhibit a greater degree of resistance to the propagation of cracks, which could contribute to the ultimate failure of the total joint replacement.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820100512
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  • 6
    Electronic Resource
    Electronic Resource
    The reactivity of α-chymotrypsin immobilized on radiation-grafted hydrogel surfaces (1977)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 111-123 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The enzymatic activity of α-chymotrypsin (CT), immobilized on hydrogelcoated polymer film supports, has been investigated. The support was prepared by radiation-graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAAc) on silicone rubber films. The enzyme was covalently coupled to the carboxylic group of MAAc via the N-hydroxysuccinimide (NHS) ester active intermediate.Increasing MAAc contents of the hydrogel resulted in increased attachment of CT. The integrity of the CT active site after attachment was assessed by an active site titration with diisopropyl fluorophosphate (DFP). As the MAAc content of the hydrogel was increased, an increasing fraction of the attached CT retained its activity to DFP. A greater fraction of CT was active towards DFP when adsorbed than when coupled.The rates of hydrolysis of some synthetic model substrates by the immobilized CT were also measured. The negative charge on the hydrogel had a large effect on the rates of these hydrolyses. The pH optimum for the hydrolysis of N-acetyl-L-tyrosine ethyl ester (ATEE) by immobilized CT was higher than that of free CT. Increasing MAAc content of the hydrogel resulted in larger shifts in the pH optimum. The maximum rates of ATEE hydroylsis per mg CT declined sharply with increasing MAAc content of the hydrogel. This is probably related to the increasing repulsive force between the ATEE (negatively charged above ⋍ pH 9.5) and the hydrogel with increasing MAAc content. The activity of immobilized CT to ATEE is small compared to that of free CT, partly due to this charge effect. Conversely, the rate of hydrolysis of BAEE, a positively charged substrate, by immobilized CT at pH 11, is almost fourfold greater than that by free CT at its pH optimum.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820110111
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  • 7
    Electronic Resource
    Electronic Resource
    Fracture characteristics of acrylic bone cements. II. Fatigue (1977)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 609-624 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The vital first phase of the overall materials study to protract the life of total joint replacements is the identification of the fracture toughness and fatigue properties of bone cements. Information gained from fatigue testing, performed in a manner which simulates in vivo conditions, and fracture toughness, which is a measure of the propensity of a crack to propagate, is the first step towards the prediction of the life of the total joint replacement. Part I of this study identified the fracture toughness characteristics of two acrylic bone cements, while the present work has been concerned with determining the fatigue behavior by means of tests conducted in a rotating bending fatigue apparatus. Fatigue specimens were fabricated under conditions which approximated clinical procedures and then tested while immersed in bovine serum at 37°C in order to simulate in vivo conditions. In addition, a similar study was completed on specimens tested in air at ambient temperature for purposes of comparison. Testing was conducted in both of these environments on specimens containing zero and 10.0 wt % BaSO4. Cyclic loading frequency was maintained between 1200 and 1400 cycles/min in order to insure that crack propagation was the sole mechanism of failure, i.e., failure via cyclic thermal softening was obviated.Results of this phase of the study, when analyzed by a Student t-test at the 90% confidence level with four degrees of freedom, indicate that the fatigue life of specimens tested in bovine serum at 37°C is superior to that of specimens tested in air at ambient temperature. The addition of BaSO4 to Simplex-P cement, while not significant at the 90% confidence level, was significant in increasing the fatigue life in air at the 80% confidence level; however, this effect was not noticeable when testing in bovine serum at 37°C. Examination of the fracture surfaces enabled calculation of the critical stress intensity factor which when compared with values from an earlier work showed good agreement.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820110413
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  • 8
    Electronic Resource
    Electronic Resource
    Fracture characteristics of acrylic bone cements. II. Fatigue (1979)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 13 (1979), S. 343-343 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820130214
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  • 9
    Electronic Resource
    Electronic Resource
    Biodegradable positively charged ion exchange beads: A novel biomaterial for enhancing soft tissue repair (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 42 (1998), S. 376-386 
    Details
    ISSN: 0021-9304
    Keywords: charged beads ; soft tissue repair ; degradable ; wound healing ; crosslinked diethylaminoethanol dextran ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previous work in the area of vulnerary agents is extensive. One material of focus has been positively charged ion exchange beads, which have been shown to promote a variety of wound-healing responses in several models. The goal of this work was to improve upon the clinical utility of positively charged dextran beads by creating a biodegradable version that maintains the material's inherent efficacy. A chemical method consisting of a sodium periodate oxidation was used to create a degradable diethylaminoethanol crosslinked dextran bead. The ability of this process to create a degradable bead was verified in vitro and in vivo. Furthermore, efficacy was shown in a rat linear incision model for a variety of beads exhibiting different degradation rates. The results show that efficacy is maintained by a degradable bead, but there is a diminution of the magnitude of the response as the mass loss rate is increased. Efficacy also was investigated for a moderate but completely degrading bead material over time and dose. Wound breaking strength was evaluated at days 7, 10, 14, 21, and 28 for degradable beads at doses of 10 mg/mL and 50 mg/mL. Although little difference in efficacy was noted for the increased dose, statistically significant increases over control were seen at days 7, 10, and 14 for the 10 mg/mL dose and at days 10 and 14 for the 50 mg/mL dose. At days 21 and 28 there were no differences between treated and control wounds. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 376-386, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Pharmacologically active polymers, 13Part 12, cf. G. Franzmann, H. Ringsdorf, Makromol. Chem. 177, 2547 (1976).. Elucidation of the tumour affinity of poly[sulfadiazineacrylamide] (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 2669-2674 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly[sulfadiazinacrylamid] (5) mit 14C-Hauptkettenmarkierung wurde synthetisiert und sein Molekulargewicht viskosimetrisch durch Vergleich mit inaktiven Proben von Poly-[sulfadiazinacrylamid] mit membranosmometrisch ermittelten Molekulargewichten ähnlicher Größe bestimmt.In seinem systemischen Verhalten bei Mäusen zeigte die Verbindung einen polymerspezifisch protahierten Verlauf. Die Ausscheidungsraten des Polymeren waren vernachlässigbar gering, seine Toxizität erheblich. Es wurde im Untersuchungszeitraum in der Leber akkumuliert, aber eine Tumoraffinität zum PC6 Plasmazelltumor bei Mäusen war nicht feststellbar.
    Notes: Poly[sulfadiazineacrylamide] (5), labeled with 14C in the main chain, was synthesized and its molecular weight viscosimetrically determined by comparison with unlabeled samples of poly[sulfadiazineacrylamide] with similar molecular weights which were determined by membrane osmometry.The material showed a polymer-specific prolongation of its systemic behaviour in mice. Rates of excretion of the polymer were negligibly low, whereas the toxicity was considerable. It was concentrated in the liver during the course of the experiment, but no affinity toward the PC6 plasmacytoma in mice could be detected.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770909
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