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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 31-40 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Metallurgical observations of phenomena which influence the clinically successful performance of permanent implants and implant materials are reported. The effect of casting voids in cast cobalt chromium femoral stems of total hip replacements is discussed first. Pitting corrosion occurred in a retrieved stainless-steel implant type AISI 316 containing 2.7% Mo. The fractographic pattern of this device retrieved for fatigue failure shows typical characteristics of corrosion-enhanced fatigue.
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  • 2
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 11-21 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The outer and inner surfaces of six commercial endotracheal tube cuffs were characterized using scanning electron microscopy (SEM) and energy dispersive x-ray analysis. Lateral tracheal wall pressure (LWP) was measured at various steps of cuff inflation using a mock-trachea system. The surface characteristics of the cuffs were found to vary widely. The surface of the Lanz cuff was relatively smooth but showed a regular array of circular depressions 0.8 μm in diameter. Uniform spheres also 0.8 μm in diameter were distributed through the thickness of the membrane. The American Hi-Lo cuff surface was also relatively smooth but was covered widely with flakes of material which x-ray showed to be a clay-like substance containing aluminum, silica, and potassium. The Harlake cuff was covered widely with roughly spherical, 5-μm-diam particles, probably starch granules. The membrane itself was smooth even at 3,000X. The Foregger cuff had a rough surface and was covered with the same clay-like particles seen on the American cuff. The inner surface with irregular, uneven areas were surrounded by fissures. The Rusch Armored tube cuff was completely covered by a continuous 2-μm-thick chlorinated coating. The surface was highly convoluted and irregular. The three cuff membranes showing relatively smooth surfaces, Lanz, American and Harlake, also produced relatively low LWP at various points of cuff inflation. While we have no data to indicate that cuff surface smoothness correlates with tracheal morbidity, it would seem prudent to select cuffs that produce low LWP's with smooth surfaces for clinical use.
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  • 3
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 4
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 55-64 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioglass, which has a composition of sodium carbonate, calcium carbonate, phosphorous pentoxide and silica, has been shown to bond to living bone. This ability is dependent on controlled surface reactions. Investigators with 45S5 bioglass have demonstrated that the formation of a SiO2-rich layer and a calcium phosphate film on its surface in an aqueous environment is associated with the film bonding the bioglass to bone. The objects of this research were: 1To study SiO2 dependence on the formation of a silica-rich layer and calcium phosphate films on a bioglass surface in a simulated physiological solution, and2To establish a correlation between in vitro surface reactions and in vivo bonding ability.It was discovered that three types of reactions occur in a simulated physiological solution depending on bioglass composition: 1A calcium phosphate film and SiO2-rich layer form simultaneously and the reaction rate is fast for bioglasses which have a lower content of SiO2 (∼46 mol% SiO2).2A SiO2-rich layer forms first and a calcium phosphate film develops later between the aqueous environment and the SiO2-rich layer for bioglasses whose SiO2 content is between 46-55 mol %.3A calcium phosphate film does not form for glasses whose SiO2 content is more than 60 mol %.
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  • 5
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 93-106 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Methods by which in vitro heterogeneous phase degradation rates of the poly(n-alkyl α-cyanoacrylates) have been directly obtained are described. The data indicate that the rates of degradation in aqueous buffer solutions depend not only upon pH of the medium and length of the monomer alkyl side chain, but also critically upon polymer particle specific surface, particle size, polymer molecular weight, and molecular weight distribution. A modification of the currently held theory of degradation of these polymers is required, and postulated.
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  • 6
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 23-29 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Three-dimensional finite element analysis (FEA) has been used to determine the implant-bone interface characteristics of bioglass dental implants. The results of the FEA were verified by comparison with the results of mechanical testing performed on animal implant specimens. The results of the study showed that the assumption of a discontinuous change of elastic properties at the bone-implant interface was a poor assumption for the bioglass implants. Interface elastic moduli of 354.0, 155.0, and 47.0 MPa for conditions of 25, 50, and 100% tissue attachment were determined for the bioglass implants.
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  • 7
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 1-10 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Contact angle studies have been carried out on plasma protein layers adsorbed on selected polymer surfaces under buffered saline at 37°, in an attempt to demonstrate directly a recent suggestion that the interfacial free energy between such protein layers and surrounding liquid phase should be zero at equilibrium. Although an initial contact angle of 180° was always obtained, the angle decayed slowly to a stationary value which varied for any one drop on each polymer surface. The stationary values could be reasonably correlated with the reversible work of adhesion predicted for each polymer/protein combination, suggesting that protein desorption from the solid surface is a dominant event in the contact angle decay process. It is concluded that the data bear more relevance to the protein layer/polymer interface than to the protein layer/solution interface, and that the contact angle technique is not a suitable technique for studying the latter on biomaterials.
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  • 8
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 83-90 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Distributions of Ca-to-Ca distances have been obtained from the crystal structure of hydroxyapatite for all biologically significant planes. Most frequently, calcium ions are separated by about 4, 6.3, 7.9, and 9.0 to 9.6 Å. Frequent occurrence of distances at 10.4, 11.8, and 12.6 Å result from a Ca ion in one repeating unit being paired with a Ca in another unit cell.
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  • 9
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Individuals who suffer extensive loss of skin, commonly in fires, are acutely ill, in danger of succumbing either to massive infection or to severe fluid loss. Patients who survive these early threats must often cope with problems of rehabilitation arising from deep, disfiguring scars and crippling contractures. In this report we describe the physiocochemical, biochemical, and mechanical considerations that form the basis for two-stage design of a membrane useful as an experimental wound closure. Stage 1 of the design, applicable to short-term acute use, calls for a membrane which displaces efficiently air pockets from a carefully prepared woundbed, free of weak boundary layers, and maintains the moisture flux through the wound at an optimal level. Optimization of the surface energy modulus of elasticity, energy to fracture and moisture permeability of the membrane are among the essential attributes of Stage 1 design. Stage 2 of the design, applicable to long-term, chronic use, focuses on a nonantigenic membrane which performs as a biodegradable template for synthesis of neodermal tissue. A survey of candidate materials suggests reasons for selection of a porous, crosslinked collagen - glycosaminoglycan coprecipitate as the chemical basis of an evolving design which was initiated 10 years ago. Over the past several years a set of membranes has been iteratively designed on this basis and has been used to cover satisfactorily large experimental fullthickness skin wounds in guinea pigs. Such membranes have effectively protected these wounds from infection and fluid loss for over 25 days without rejection and without requiring change or other invasive manipulation. When appropriately designed for the purpose, the membranes have also strongly retarded wound contraction and have become replaced by newly synthesized, stable connective tissue. Several rules relating the molecular structure and morphology of these membranes to cellular response of adjacent tissue have also been derived. This report is the first in a series which details the methodology of preparation and the record of performance.
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  • 10
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 177-180 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 11
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 181-181 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 12
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 211-224 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Several kinds of polyamide microcapsules containing mammalian hemolysate were prepared by making use of the interfacial polycondensation reaction between diamines and terephthaloyl dichloride and their blood compatibility in terms of platelet adhesion was examined aiming at their ultimate clinical use as artificial red blood cells. It was found that rabbit platelets adhere onto the hemolysate-loaded microcapsules in the presence of the plasma, while no platelet adhesion takes place in the absence of the plasma. This was interpreted as indicating an important role of plasma components in platelet adhesion. Moreover, platelet adhesion was observed to be facilitated by negative charges on the surface of the hemolysate-loaded microcapsules; the more negatively the surface was charged, the more easily the platelets adhered onto the surface. Finally, the present method of assessing platelet adhesion suggested the possibility of its use for the kinetic study of platelet adhesion since it allowed us to make numerical evaluation of platelet adhesion as a function of time.
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  • 13
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 251-268 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The thrombogenicity of five suture materials - polypropylene (Prolene), polyester (Mersilene), polyglactin 910 (Vicryl), nylon (Ethilon), and silk - was examined in vivo by scanning electron microscopy. The most blood-compatible material appeared to be Prolene. A rather satisfactory antithrombogenciity was shown by Mersilene, in comparison with which Ethilon and Vicryl provided less thromboresistance. The possible connection between the chemical changes which occur during the hydrolysis of Vicryl and its blood compatibility is discussed. Of the tested materials, silk proved to be the most thrombogenic. This study shows that the thrombogenicity of a suture material could be easily and conveniently tested in an experimental model by scanning electron microscopy, thus enabling the first choice of a suitable suture for the cardiovascular surgery, before one continues with other more sophisticated methods for the evaluation of thromboresistance.
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  • 14
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 289-309 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: It is known that tissues surrounding the site of an implanted prosthetic alloy are exposed to increased concentrations of the metals comprising the alloy. However, the exact identity and concentration of such metallic products are usually unknown, thus limiting the possibilities for quantifying any observed toxicological response to the metals. This report describes some of the effects of increased concentrations (7.5-30 μg/ml; 1-5 × 10-4M) of cobalt (as CoCl2·6H2O) and of nickel (as NiCl2·6H2O) on the growth and morphology of cultured mouse fibroblasts. Ultrafiltration experiments indicated that much of the total Co or Ni present in cell culture medium could become bound to macromolecular serum components of the medium. Morphological changes and depressions in the cell growth rate were found to result from high concentrations (15-30 μg/ml) of either Co or Ni. However, lower concentrations of nickel may have produced some stimulation of cell growth, whereas all concentrations of Co studied were found to depress the rate of cell growth. The growth rate of actively proliferating fibroblasts was quite sensitive to variations in the concentration of either cobalt or nickel. Increased concentrations of cobalt or nickel, therefore, might also affect the normal reconstructive activity of fibroblasts in vivo.
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  • 15
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 329-338 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In vitro and in vivo experiments were performed on polyglycolic acid and plain catgut sutures to study the effects of bacteria on their rate of degradation. Experiments with Strep, mites, E. coli and Staph. albus in culture showed that the polyglycolic acid sutures degraded faster in broth controls than in a broth containing bacteria as measured by the loss in breaking strength. No difference was observed with the catgut. Polyglycolic acid sutures in subcutaneous sites in rats inoculated with Staph. albus again degrade slower than in similar wounds which were not deliberately infected. With high bacterial counts, the catgut showed the reverse trend although no differences were noted at lower counts.
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  • 16
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 17
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 359-371 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Two types of fracture toughness specimen, the tapered cleavage (TC) and single edge notch (SEN), are compared. Their reproducibility, accuracy, and ease of preparation are investigated. The fracture toughness of four types of acrylic resin, heat cured, autopolymerized, injection molded, and high impact resistant, has been determined by one or both of the above methods. High impact acrylic proved too ductile for either of the specimens to be used to assess K1c; however, these deviations from brittle behavior were revealed by the tests and some insight into impact resistance was gained. The SEN specimens proved capable of distinguishing between the fracture toughness characteristics of the four types of denture base acrylics and proved easy to fabricate. The TC specimens proved difficult to fabricate requiring specialized equipment; however, once made, the specimens revealed more of the fracture process than did the SEN specimens.
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  • 18
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    Journal of Biomedical Materials Research 14 (1980), S. 427-434 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The amount of methyl methacrylate monomer present in bone tissue immediately adjacent to implanted bone cement that has polymerized in vivo has been determined. Poly(methyl methacrylate) was implanted into the distal femoral condyle of the dog and allowed to polymerize. At various times following polymerization, samples were removed and sections adjacent to the cement were cut and subjected to homogenization followed by liquid gas chromatographic determination of the amount of methyl methacrylate monomer present. The highest concentration of methyl methacrylate monomer present in bone tissue was 0.140% in the 1000 μm of bone tissue adjacent to bone cement immediately after polymerization of the cement. The concentration was very similar (0.137%) 1 hr after cement polymerization, but dropped off rapidly following that with no free methyl methacrylate monomer present in bone tissue adjacent to cement after 4 hr following cement polymerization.
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  • 19
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    Journal of Biomedical Materials Research 14 (1980), S. 447-454 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An evaluation of the biophysical changes of methylcholanthrene induced tumor (M4) in laboratory animals receiving four different alloplastic implants was conducted. The implants are silicone, polyether urethane, poly(methyl methacrylate), and bioglass. The tumor was allowed to grow to a large size in 28 days and then removed by shelling it from the surrounding tissue. Three different analytic volumetric measurements were carried; size in cm3, volume in milliliters and weight in grams. Statistical analysis on the three different analytic measurements did not disclose any significant differences in tumor growth potential between the control and the experimental groups. We conclude that in this study we were unable to demonstrate any tumor “facilitation” effect by any of the implantable polymers used. Therefore, there is no contraindication in using the polymers to reconstruct defects produced by cancer ablative procedures.
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  • 20
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 467-476 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Thrombin adsorbed onto Cuprophane or poly(vinyl chloride) (PVC) was shown to be inactive with respect to amidase activity. Desorbed thrombin from these two artificial surfaces showed only low amidase activity. However, in the presence of albumin, the surface-bound thrombin appeared to exhibit increased amidase activity. This apparent activity may be due to the action of thrombin displaced from the surfaces by albumin. Thrombin bound to Cuprophane or PVC was shown to be capable of reacting with antithrombin III (AT III) only in the presence of heparin. On the other hand, AT III bound to Cuprophane or PVC was unable to react with thrombin in either the absence or presence of heparin. Fibrin formation on or at surfaces was demonstrated by phase contrast microscopy when Cuprophane or PVC pretreated with thrombin and carefully rinsed was incubated in a fibrinogen solution. This fibrin formation is time dependent and likely is the result of direct interaction of adsorbed thrombin with fibrinogen in solution. Glass, Cuprophane, and PVC pretreated with thrombin were shown to attract more platelets than respective untreated surfaces. The enhancing effect of adsorbed thrombin on platelet adhesion was similar to the enhancing effect of adsorbed fibrinogen. Thrombin adsorbed onto PVC and crosslinked by glutaraldehyde treatment was shown to be antigenically active with a 125I-labeled monospecific antithrombin IgG produced in rabbits. No other plasma proteins adsorbed singly or from plasma or serum onto PVC reacted significantly with the antithrombin IgG preparation. The possible significance of these observations is discussed.
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  • 21
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    Journal of Biomedical Materials Research 14 (1980), S. 435-446 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of thermal coefficient of expansion (α) mismatch on porcelain-metal bonding is frequently referred to in the dental literature. Thermally induced stresses may develop at metal-porcelain system interfaces due to differences in the coefficients of thermal expansion of the porcelains, metals, and metal oxides. The objective of this research is to characterize alloy and porcelain expansion behavior as a first step in developing a more specific definition of thermal compatibility. It is clear from comparisons of porcelain data and alloy data that the porcelain has expansion characteristics which are quite different from those of the alloys. The overall differences in values between these alloys and porcelains constitute a mismatch. First run dilatometric heating measurements for porcelain yield large differences between ΔL/L and α values as compared to cooling measurements. For a comparison of alloy and porcelain expansion characteristics, data should be obtained at several temperatures up to the glass transition temperature (Tg) of the porcelain.
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  • 22
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    Journal of Biomedical Materials Research 14 (1980), S. 455-466 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This short report concentrates on a close look at the immunological status of experimental animals which were implanted with a known dose of tumor and polymer implant. The implanted polymers used represented the most common biocompatible materials employed in current surgery. The immunological studies all were done in vitro on the cellular level. The studies suggested that there is a noticeable change of the immune system when inorganic biocompatible polymers are used in experimental animals.
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  • 23
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    Journal of Biomedical Materials Research 14 (1980), S. 487-497 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The linear, crosslinked amylose-succinate hemostatic agent, IP760, has been evaluated for its interaction with aminoglycosidic antibiotics. The highly structured polymer appears to act as a cationic exchange resin which binds the basic aminoglycosides. Binding of these agents to IP760 is reversed by increased pH and/or increased ionic strength. Dialysis experiments demonstrated that 85 and 90% of the bound gentamicin was released at pH 7.5 and 8.0, respectively, over a period of 36 hr. Formation of the IP760-antibiotic complexes suggests potential medicinal use for hemostasis and slow release of the antibiotic for prophylaxis of postsurgical contamination or infection.
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  • 24
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    Journal of Biomedical Materials Research 14 (1980), S. 477-485 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of membranes was prepared by air-drying the thin layers of N-acyl- and N-arylidene-chitosan gels. Their flow rates of water and permeabilities of various compounds were examined. N-Acylchitosan membranes were stable in both dilute acid and alkali, but N-arylidene-chitosan membranes were unstable in dilute acid. N-Acetylchitosan membranes were stable in formic acid at room temperature for up to 7 hr. The flow rates of water through N-acetylchitosan membranes were 10.0-23.6 × 10-3 ml/cm2 min under a pressure of 3 kg/cm2, and were unchanged by the membrane thickness (12-60 μm). The increase of carbon numbers for N-acyl groups caused a slight decrease in the flow rates, and the flow rates were decreased by partial O-acetylation of N-acetylchitosan membranes. The flow rate of water through chitosan membranes (thickness 30-35 μm) was 7.1 × 10-4 ml/cm2 min, which was decreased by an increase in the membranes thickness. Low-molecular-weight compounds (MW 〈 2900) passed through these membranes, but high molecular-weight compounds (MW 〉 13,000) did not pass through.
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  • 25
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    Journal of Biomedical Materials Research 14 (1980), S. 529-531 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 26
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    Journal of Biomedical Materials Research 14 (1980), S. 499-509 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Kinetics of platelet adhesion from suspension to various substrates leads to Langmuir isotherm types of curves, both for suspensions in which the platelets were isolated by means of gel filtration as well as by centrifuging and washing. The level of platelet adhesion increases with increasing surface tension of the substrate. These results cannot be explained on the basis of the theoretical transport model of Ruckenstein et al. The plot of the platelet adhesion at equilibrium vs. γsv brings the observations in yet closer agreement with thermodynamic predictions based on free energy calculations than was found previously for the adhesion of platelets after short contact times between platelet suspension and substrate.
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  • 27
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    Journal of Biomedical Materials Research 14 (1980), S. 537-543 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 28
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    Journal of Biomedical Materials Research 14 (1980), S. 533-535 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A highly reproducible seeded crystal growth method has been used to study enamel mineralization in the presence of traces of fluoride ion. The resulting increased rate of remineralization over a range of calcium phosphate supersaturation may be attributed to the formation of surface fluorapatite.
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  • 29
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    Journal of Biomedical Materials Research 14 (1980), S. 545-545 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 30
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    Journal of Biomedical Materials Research 14 (1980) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 31
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    Journal of Biomedical Materials Research 14 (1980), S. 511-528 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Several methods are compared for preparing collagen-glycosaminoglycan (GAG) membranes of high or low porosity. Collagen-GAG membranes have been used to cover satisfactorily large experimental full-thickness skin wounds in guinea pigs over the past few years. Methods studies as means for controlling pore size are confined to purely physical processes which do not require use of additives or chemical reagents to form the porous membrane. We find that membranes, initially swollen in distilled water or saline, shrink linearly to no less than 94% of original dimension after freeze drying; to 75% after critical point drying (from CO2, following water-ethanol exchange); and to 41% of original dimension following air drying from the swollen state. Scanning electron microscopic study of the pore structure resulting from each drying procedure confirms our major conclusion: A carefully designed freeze drying process, two variants of which are described in detail, yields membranes with the highest mean pore size, as measured by quantitative stereological procedures. Critical point drying gave significantly more shrinkage and a lower mean pore size than either one of the two freeze drying procedures used.
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    Journal of Biomedical Materials Research 14 (1980), S. 567-586 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Repair or replacement of the damaged anterior cruciate ligament (ACL) is a significant clinical problem. A design utilizing ultrahigh-molecular-weight polyethylene (UHMWPE) was developed and marketed by an orthopaedic device manufacturer. Mechanical failure rates of greater than 10%/year postoperatively raised the issue of the adequacy of UHMWPE in that design. A study has been made to estimate the forces in the human anterior cruciate ligament for young, middle age, and older patients and to thus derive the minimum materials requirements for a now withdrawn prosthetic anterior cruciate ligament (PACL) design. It is concluded that UHMWPE does not possess adequate yield, creep, or fatigue properties to meet the design. Furthermore, consideration of the varying requirements on the PACL, due to differences in age and activity levels of patients, suggest that a band-type design offers a better possibility of achieving adequate materials performance in the ACL prosthetic replacement.
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  • 33
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    Journal of Biomedical Materials Research 14 (1980), S. 547-556 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The polarization resistance and anodic polarization curves of three amalgam types were determined in saline solution. Corrosion currents were determined by extrapolation of anodic Tafel slopes. A good correlation was found between corrosion currents and reciprocal polarization resistances, according to Ic = 0.02/PR.
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  • 34
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    Journal of Biomedical Materials Research 14 (1980), S. 557-566 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The mechanical properties of the hydrogel membrane of poly(methyl methacrylate-N-vinylpyrrolidone) were studied for the purpose of making soft contact lenses for extended wear. The dependence of tensile fracture energy, flexibility, and recovery from deformation on the water content and thickness of the hydrogel membrane was studied. Reducing the thickness of a lens was found to exert a more advantageous effect than increasing its water content on maximizing the tensile fracture energy under the condition of an adequate supply of oxygen to the cornea through the contact lens. As long as its water content is controlled between 63 and 78%, the contact lens made of poly(methyl methacrylate-N-vinylpyrrolidone) has the flexibility on the same order as that of conventional soft contact lenses of poly(2-hydroxyethyl methacrylate). The rate of recovery from deformation increases with water content, and the residual elongation is negligible in the range of water content over about 70%. It is concluded that practical requirements for use of these contact lenses, determined by these three mechanical properties, can be satisfied at the same time if the water content of the contact lens is adjusted at about 70%.
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  • 35
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    Journal of Biomedical Materials Research 14 (1980), S. 587-595 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study was conducted which examined the influence of electropolishing on the corrosion resistance of a cold rolled 316L stainless steel. Test specimens were surface prepared to a final mechanical finish of wetted 600 grit SiC paper, prior to electropolishing. An o—H3PO4/Glycerol/H2O electropolishing solution was employed for times of 15, 20, and 25 min. Control specimens were surface prepared only to the final mechanical finish. Anodic polarization tests were performed in a deaerated Ringer's solution (37°C) which was acidified to pH 1, with HCl. The electropolished specimens demonstrated increased corrosion resistance, when compared to the control specimens. This was evidenced for the former by more anodic corrosion and breakdown potentials, and the absence of a dissolution peak which was observed for the control specimens at the initial polarization potentials. Surface hardness measurements indicated that this increase in corrosion resistance was produced, in part, by the removal of the cold worked surface layer produced by the mechanical finish. In terms of increasing corrosion resistance, no optimum electropolishing time was found within the 15-25 min treatment period.
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    Journal of Biomedical Materials Research 14 (1980), S. 597-605 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: When ground to a suitable form, flexural strength of single crystal alumina (Al2O3) decreases to as low as one third the strength of the intact crystal. This flexural strength decrease is, however, recovered by chemical etching at a high temperature to eliminate surface defects caused by grinding. By using this strength recovery treatment, various types of single crystal implants with fine structure were able to be designed. Four kinds of single crystal bone screws and single crystal dental implants of screw and anchor type were designed. Flexural strength and impact strength of the implants were measured.
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    Journal of Biomedical Materials Research 14 (1980), S. 619-630 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The reactions of covalently immobilized heparin, abbreviated as I-Hep, with thrombin or Factor Xa were investigated both in the presence and absence of antithrombin III, AT III. Although I-Hep was able to bind to thrombin, the complex formation of thrombin and I-Hep did not affect the thrombin activity when measured by using a small artificial substrate, a peptide-MCA. Similarly, Factor Xa bound to I-Hep, but the activity of Factor Xa was not decreased in the absence of AT III, when a peptide-MCA was used for Factor Xa assay. Thrombin bound to I-Hep in much larger amounts than Factor Xa. Thrombin and Factor Xa were instantaneously inhibited by AT III in the presence of soluble heparin. However, when I-Hep was used instead of soluble heparin, instantaneous inhibition was not observed. When a natural, high-molecular-weight substrate was used for assay, the results were dependent on the structure of the immobilization carrier. Heparin immobilized on Sepharose 4B or Poly HEMA showed considerable prolongation of plasma recalcification time. However, heparin immobilized on the surface of PVA fiber did not prolong plasma recalcification time.
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  • 38
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    Journal of Biomedical Materials Research 14 (1980), S. 631-638 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An in vivo model has been designed to study the acute response of exposed or unexposed dental pulp to the topical application of various biomaterials. This model permits sequential microscopic observations of the microvascular system of dental pulp before and after application of pulp capping agents, cementing agents, or cavity liners. The use of this experimental model provides useful information related to the tolerability of dental pulp to various biomaterials used in dentistry. Furthermore, this model serves as a useful supplement to more traditional long term methods for evaluating the biocompatability of dental materials.
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    Journal of Biomedical Materials Research 14 (1980), S. 607-618 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A direct physicochemical bond between alkali-rich bioglass or glass ceramic (45 S 5 A and B, Hench) or alkali-poor glass ceramic (KG S, Brömer) and bone has been well documented. Since long-term studies have revealed the interface to be subjected to remodeling of the bone and to increased focal disintegration of the implant, glass ceramics of reduced solubility have been developed by lowering the Na2O content and adding Al2O3, Ta2O5, TiO2, and Sb2O3. Implants of glass ceramic KG S and different compositions with reduced solubility have been studied histologically 14, 29, or 30, 60, 119, and 245 days after implantation in the femur of male Sprague-Dawley rats. Implants of KG S are anchored at an interface with bone connection, which is known to provide for application of considerable shear and tensile strengths; whereas, at the interface of ceramics of reduced solubility, soft tissue, chondroid and osteoid are mainly observed. The dynamics of the events at the interface indicate a disturbance of the transformation of chondroid cells into osteoblasts and of the mineralization of osteold. This disturbance of pathophysiologic processes during bone healing or bone regeneration is discussed.
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Interfaces were formed between acrylic bone cement and three commonly used surgical alloys (316L SS, Co—Cr—Mo, and Ti—6A1—4V), in an attempt to further define cementation parameters of acrylic bone cement for use in orthopaedic surgery. Metal/cement interfaces were made at three distinct times during the setting cycle of the cement and were cured for 1 hr, 1 day, and 1 week. The metals were prepared with roughly polished or finely polished prepassivated surfaces. Tensile bond strengths and residual cement on metal coverage data indicated that, for each metal system, interfaces created prior to and at the onset of the dough stage formed superior interfaces for implanation compared to those formed late in the dough stage. Furthermore, electropolishing plus prepassivation offered a more efficient bonding surface than mechanical polishing.
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    Journal of Biomedical Materials Research 14 (1980), S. 653-663 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of 16 pure metals on the in vitro growth of a form of dental caries producing Streptococcus mutans was studied under both aerobic and anaerobic conditions. Cobalt and copper were consistently observed to be inhibitory. With less consistency nickel, titanium, iron, and vanadium also exhibited ability to inhibit growth of the organism. Bacteriostasis apparently is contingent upon the presence of a corrosion process. The bacteriostatic agent is of uncertain identity and could be a corrosion product or a process secondary to the occurrence of corrosion. Concentrations of metals after 6 days of electrochemical dissolution in the growth medium were measured via electron microprobe analysis and compared with the amount of inhibition which resulted. Threshold concentrations above which growth did not occur were identified. As measured by threshold concentrations, wide variability between metals exists in the ability to inhibit the growth, with cobalt being particularly effective at small concentrations. This implies a sensitivity on the part of the organism that is different for different metals. The threshold concentration varied between aerobic and anaerobic conditions. Streptococcus mutans appeared more resistant to the effects of the metals under anaerobic conditions even though little difference in the amount of corrosion was detected.
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    Journal of Biomedical Materials Research 14 (1980) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 43
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    Journal of Biomedical Materials Research 14 (1980), S. 665-687 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Graft copolymer systems have frequently been suggested for biomedical applications. Since the properties of polymers are altered by the grafting process, thorough characterization is critical, particularly for the surface region of these copolymers. This review briefly discusses the grafting process and then describes characterization procedures for graft copolymers. Gravimetric characterization, thermodynamic measurements, surface chemistry analysis, and surface topographical analysis are considered in detail. Also, the relevance of materials characterization for predicting and understanding the biocompatibility response is discussed. Most of the analytical techniques described are applicable to all biomaterials and should be considered for the routine characterization of materials which will be interfaced with biological systems.
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    Journal of Biomedical Materials Research 14 (1980), S. 689-703 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Failure behavior of a polyolefin elastomer which is a candidate material for blood pump applications has been studied under uniaxial and equibiaxial test conditions. Both static and dynamic (fatigue) testing were performed to study four aspects of material failure behavior as suggested by a cumulative damage failure model. Results from testing a standard formulation butyl rubber are presented for comparison. Our results show that the uniaxial failure behavior under static loads for the butyl rubber is superior to that of the polyolefin rubber at high loads but that the polyolefin is superior at low loads. Under fatigue loading conditions, the failure times for both rubbers decrease with increasing test frequency. The observed frequency dependence lies between that predicted by the cumulative damage model and that predicted by a cycle dependent fatigue model. The distribution of failure times for the polyolefin rubber is broader than that for the butyl rubber. For both uniaxial and equibiaxial testing, the distribution of failure times changes in going from the static testing to dynamic testing. This is true for both rubbers.
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  • 45
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    Journal of Biomedical Materials Research 14 (1980), S. 705-712 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In order to investigate whether the immune system is involved in the degradation of hydroxylapatite as implant material the adsorption behavior of several serum proteins to hydroxylapatite was studied and compared with the adsorption to other calcium phosphate compounds (Ca3(PO4)2, CaHPO4), calcium carbonate, aluminium oxide, and zinc oxide. It was found that complement factors, C4 and C3, and α2-HS-glycoprotein adsorbed to the calcium phosphate compounds, but not to the other materials. IgG and albumin were adsorbed to all investigated compounds. These results suggest that the complement factors are directly adsorbed on the surface of the calcium phosphate compounds. Therefore, the activation of complement, if any, proceeds by the classical pathway. The binding of complement factors to the calcium phosphate salts investigated points to a more specific involvement of the immunosystem in the degradation process of calcium phosphate implants.
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  • 46
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    Journal of Biomedical Materials Research 14 (1980), S. 723-730 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Pyrophosphate labeled with 99Tc was evaluated as an indicator of the calcification which occurs after implantation of polymeric materials in rats. Poly(2-hydroxyethyl methacrylate), both porous and homogeneous, had been implanted. 99Tc pyrophosphate was applied intravenously to rats in intervals from 14 days to 15 months. Scintigraphy, x-ray examination, and histology were carried out. The ratio of specific activity in the capsule around the implant to specific activity in the reference tissue was determined. The cumulation of activity was parallel with the development of calcification as revealed by histology. The method can be used not only in the screening test of new polymeric materials, but also in a quantitative determination of the degree of calcification in general.
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  • 47
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    Journal of Biomedical Materials Research 14 (1980), S. 713-721 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Dense (97-99.9%) hydroxylapatite ceramics were implanted in muscle and bone tissue of rats. The aim of this study was to compare apatite implant material made of commercially available powder with laboratory powder prepared in a painstaking manner. Biocompatibility, biostability, and adherence to bone were evaluated. In muscle tissue the implants were found to be encapsulated with a very thin connective tissue layer. Implantation in excavated bone tissue resulted with new bone directly deposited against the implant surface, irrespective of the type of hydroxylapatite used. When the implants were protruding from the bone surface, bone appeared to grow up to the edge of the protruding part of the implant. A very strong bonding developed; push-out tests indicated that the bone fractured but never at the interface. Histologic studies proved that a sleeve of newly formed bone closely encased the implant, regardless of shape. It was concluded that dense apatite ceramics are fully compatible with the tibia of the rat and that no degradation of the implant material occurred for intervals of up to 6 months after implantation. The very strong bonding without mechanical retention indicated continuity between artificial hydroxylapatite and natural bone. No difference was found between the biological behavior of the hydroxylapatites prepared from commercial or laboratory starting powders.
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    Journal of Biomedical Materials Research 14 (1980), S. 743-751 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polymer-coated, activated charcoal granules have found considerable use for the direct detoxification of blood in cases of uraemia and drug overdose. Although polymer coating materials are presently selected for their biocompatibility, more selective polymers could be used to increase the adsorption capacity for specific drugs and toxins. To gain an understanding of the fundamental factors influencing these adsorbent systems, we have investigated a possible selective coating material, nylon 6 and studied its influence on adsorption rates of simple model compounds when applied as a thin coat to activated charcoal granules. Thermodynamic studies have shown that phenolic compounds interact with the polymer by a hydrogen bonding mechanism, whereas nonphenolic compounds probably bind less strongly due to Van der Waals type interactions. Kinetic studies have shown that the selectivity of charcoal granules for phenolic compounds was increased by coating the granules with a thin layer of nylon 6. The increase in selectivity is probably a result of the different binding mechanism between solute and the polymer. These studies have shown that possible selective coatings may be evaluated more effectively on the basis of simple preliminary drug-plastics interaction studies.
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    Journal of Biomedical Materials Research 14 (1980), S. 731-742 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Under certain circumstances, e.g., when treating “denture sore mouth” or after the provision of immediate dentures, dentures may be lined with soft rubberlike materials which have Young's moduli within the range ≃105 N m-2. Measurement of the compression modulus Ec of such soft liners is described and Gent and Lindley's method of calculating Young's modulus E was evaluated. It was established that the Young's modulus may be calculated using: Ec = E(1 + 2kS2), where k = 1 for soft rubbers, and for disks S is a shape factor and = radius/2 × thickness. It is also shown that Young's modulus is a linear function of log(rate of strain) for both tension and compression measurements. When gellation has occurred subsequent to mixing there is an increase in Young's modulus due to loss of ethanol. When immersed in brine the elastic modulus remains approximately constant from a day to a week or longer.
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    Journal of Biomedical Materials Research 14 (1980), S. 765-776 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A highly sensitive method to localize aluminum oxide or polyethylene wear particles in biological tissues is presented. Using the scanning electron microscope (SEM) with a special cathodoluminescence detector system, small amounts of these foreign materials can be visualized in simple frozen sections by their bright luminescence, even at low magnifications (200X). At higher magnifications, a differentiation of free as well as phagocytized aluminum oxide and polyethylene particles can be made due to their different behavior in light emission. In addition, aluminum oxide such as other metals can be identified by x-ray microprobe analysis. This combination of SEM with microprobe analysis and with the highly sensitive cathodoluminescence mode enables to detect and identify wear products from all the materials, commonly used in manufacturing artificial joint replacements.
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    Journal of Biomedical Materials Research 14 (1980), S. 753-764 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Glutaraldehyde is commonly used to control physical and biological properties of collagen structure by means of intramolecular and/or intermolecular crosslinking of collagen molecules. Solubility, antigenicity, and biodegradation of naturally occurring or reconstituted collagenous matrices are effectively reduced by glutaraldehyde treatment. Adverse biological reactions to glutaraldehyde have been limited to infrequent contact dermatitis and to biocidal effects which are exploited in chemical sterilization media. In the present study of glutaraldehyde-tanned collagen sponge, the presence of glutaraldehyde was correlated with cytotoxic effects upon fibroblasts in tissue culture and foreign body giant cell reaction to bioimplants of the sponge. Fibroblast growth in tissue culture is 99% inhibited at media concentrations of 3.0 ppm glutaraldehyde. Extracts of glutaraldehyde collagen sponge in aqueous media at pH 7 and 4.5 yielded 6 μg and 65 μg glutaraldehyde per gram of collagen sponge, respectively. The yield increased tenfold at pH 4.5. Observations indicate that leaching of the glutaraldehyde from glutaraldehyde-tanned collagen sponge is sufficient to produce potentially adverse cellular effects both in vivo and in vitro.
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    Journal of Biomedical Materials Research 14 (1980), S. 777-788 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In a clinical evaluation of marginal deterioration, 475 amalgram restorations were equally distributed in a 6 × 4 × 2 × 3 factorial design, based on alloy, operator, tooth, and number of restored surfaces. All factors except the last had a statistically significant effect after 6, 12 and 18 months. There were no consistent two-way interactions over time.
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    Journal of Biomedical Materials Research 14 (1980), S. 803-811 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this excellent and analytical article, the immediate past President of the Society for Biomaterials reviews some of the most salient aspects of the Biomaterials scientists' work. His observations and comments are significant and crystallize current thought succinctly and with intelligence. - Ed.
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    Journal of Biomedical Materials Research 14 (1980), S. 789-801 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Morris Hepatoma experimental tumor in ACI rats is treated with small anodal direct current via an implantable power pack unit. There was major retardation in tumor growth when the treatment was started early. There was enhancement of tumor growth when the treatment was started early and then was discontinued. There was no statistical difference in growth control of the experimental tumor when the electrotherapy was given after the half-life of the tumor was achieved. This last point will be the most important to the clinician scientist, for it simulates the clinical situation that faces the treating physician.
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    Journal of Biomedical Materials Research 14 (1980), S. 813-815 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 14 (1980), S. 817-823 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 14 (1980), S. 825-825 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 14 (1980), S. 91-92 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 14 (1980), S. 145-154 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study was conducted to measure the permeability to oxygen (PmO2) of microporous membranes coated with ultra-low-temperature isotropic (ULTI) carbon. Carbon-surfaced membranes were fabricated by application of a thin complete layer (0.7 to 1.7 microns thick) of ULTI carbon onto one surface of a microporous substrate. Based upon the average values of 27 measurements in a diffusion cell, a mean reduction in PmO2 of only 10% results following the treatment of the microporous substrate with ULTI carbon. The values for PmO2 are not dependent upon the thickness of the carbon film over the range of film thickness of 0.7 to 1.7 microns. When coupled with the known antithrombotic characteristics of ULTI carbon, an oxygenator incorporating carbon-surfaced microporous membranes has the potential for use in clinical extracorporeal membrane oxygenation (ECMO).
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    Journal of Biomedical Materials Research 14 (1980), S. 161-171 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: From 0 to 24 hours at an initial static stress of 34.5 MPa and in the temperature range of 0 to 60°C, the creep behavior of four different one-week-old dental amalgams was monitored in a recently developed minispecimen creep apparatus. In most instances the behavior could not be described by a linear relationship. Therefore, the usefulness of calculating creep rate based upon only two times, i.e., 1 and 4 hours, must be questioned. On the other hand, the observed creep kinetics were found to follow accepted nonlinear models of dislocation/obstacles interactions which may be thermally activated.
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  • 61
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Detailed methodology is described for the reproducible preparation of collagen-glycosaminoglycan (GAG) membranes with known chemical composition. These membranes have been used to cover satisfactorily large experimental full-thickness skin wounds in guinea pigs over the past few years. Such membranes have effectively protected these wounds from infection and fluid loss for over 25 days without rejection and without requiring change or other invasive manipulation. When appropriately designed for the purpose, the membranes have also strongly retarded wound contraction and have become replaced by newly synthesized, stable connective tissue. In our work, purified, fully native collagen from two mammalian sources is precipitated from acid dispersion by addition of chondroitin 6-sulfate. The relative amount of GAG in the coprecipitate varies with the amount of GAG added and with the pH. Since coprecipitated GAG is generally eluted from collagen fibers by physiological fluids, control of the chemical composition of membranes is arrived at by crosslinking the collagen-GAG ionic complex with glutaraldehyde, or, alternately, by use of high-temperature vacuum dehydration. Appropriate use of the crosslinking treatment allows separate study of changes in membrane composition due to elution of GAG by extracellular fluid in animal studies from changes in composition due to enzymatic degradation of the grafted or implanted membrane in these studies. Exhaustive in vitro elution studies extending up to 20 days showed that these crosslinking treatments insolubilize in an apparently permanent manner a fraction of the ionically complexed GAG, although it could not be directly confirmed that glutaraldehyde treatment covalently crosslinks GAG to collagen. By contrast, the available evidence suggests strongly that high-temperature vacuum dehydration leads to formation of chemical bonds between collagen and GAG. Procedures are described for control of insolubilized and “free” GAG in these membranes as well as for control of the molecular weight between crosslinks (Mc). The insolubilized GAG can be controlled in the range 0.5-10 wt. % while “free” GAG can be independently controlled up to at least 25 wt. %; Mc can be controlled in the range 2500-40,000. Studies by infrared spectroscopy have shown that treatment of collagen-GAG membranes by glutaraldehyde or under high-temperature vacuum does not alter the configuration of the collagen triple helix in the membranes. Neither do these treatments modify the native banding pattern of collagen as viewed by electron microscopy. Collagen-GAG membranes appear to be useful as chemically well-characterized, solid macromolecular probes of biomaterial-tissue interactions.
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  • 62
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    Journal of Biomedical Materials Research 14 (1980), S. 173-175 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 63
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    Journal of Biomedical Materials Research 14 (1980), S. 183-183 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 64
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    Journal of Biomedical Materials Research 14 (1980), S. 225-237 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Skeletal fixation of permanent implants by new methods such as fixation by mechanical interlocking of bone with porous prosthetic coatings or chemical bonding with bioactive materials shows growing potential. This paper reports on the resulting skeletal fixation of a combined porous and bioactive material. Metal plugs with a porous metal fiber coating impregnated with hydroxyapatite were implanted for 2, 4, and 12 weeks and were compared to the parent porous, nonbioactive, metal fiber material. Statistical analysis of the interfacial failure shear stress, as obtained by mechanical testing, shows there is a marked influence of hydroxyapatite impregnation on the rate of bone ingrowth and the strength of the interfacial bond the few weeks following surgery. Microscopical examination reveals that the apparent stimulation of bone ingrowth into the surface pores of the implant is the reason for the increased rate of bond formation. The results are of particular clinical interest: with an increased rate of bone ingrowth, weight bearing might be allowed much earlier, thus reducing the recuperation period.
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  • 65
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    Journal of Biomedical Materials Research 14 (1980), S. 279-288 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This research is part of a continuing program for the development of a coaxial depth electrode for research and diagnostic studies of neurological diseases. The requirements for this electrode include (1) strength and resistance to buckling sufficient to ensure self-forced penetration of brain tissue to a depth of 6 cm; (2) biocompatibility of the materials employed; (3) resistance to brittle fracture; and (4) a total diameter of less than 200 μm to minimize tissue damage. Earlier synthesis efforts using chemical vapor deposition techniques have been successful, although the process yield was 40% and an outer insulating layer had yet to be deposited. Plasma polymerization processes have been employed to realize an increase in the yield and provide an outer insulating layer. The starting material is W-26 at.% Re wire, nominally 125 μm in diameter. Hexamethyldisilazane (CH3)3SiNHSi(CH3)3 is used to deposit the insulating layers. The paper describes factors influencing the choice of materials, deposition techniques, and properties of electrodes.
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  • 66
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    Journal of Biomedical Materials Research 14 (1980), S. 339-339 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 67
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    Journal of Biomedical Materials Research 14 (1980), S. 373-382 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A diffusion apparatus for the measurement and monitoring of microleakage is described. Radioactive ions are used to measure the diffusion across a section of a filled tooth. A study was made of the sealing ability of some amalgams and a composite resin filling material.
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  • 68
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    Journal of Biomedical Materials Research 14 (1980), S. 393-403 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Adsorption of bovine albumin, γ-globulin and fibrinogen from phosphate buffer solution (pH = 7.5) onto several polymer films was studied using the radioiodinated proteins (125I). The kinetics of desorption of the proteinated polymer films in bovine plasma was determined. Contact angle measurements on these same polymers allowed the calculation of dispersive (WAd) and polar (Ip) components of the polymer-protein solution system. Results from these measurements show that the nondispersive-dispersive force balance at the polymer-protein solution interface, expressed by the Ip/WAd ratio, is an important factor for binding of proteins on polymer surfaces. The purity of fibrinogen and the cleaning procedures for the polymer surfaces influence the absolute values of proteins adsorbed on polymer surfaces.
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  • 69
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    Journal of Biomedical Materials Research 14 (1980), S. 185-197 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An effective method for controlling the release of drugs is entrapping them in a polymeric carrier. This research employs the application of radiation polymerization of glass-forming monomers at low temperatures for the preparation of polymer composite materials comprising such biofunctional bodies and substances as enzymes, microbial cells, organellas, and drugs. The glass-forming monomers are very advantageous for entrapping these biofunctional components because they are formed easily in an extremely viscous supercooled state at low temperatures, efficiently disperse a biofunctional component, and polymerize at a high rate in this state. Therefore, they can catch and trap the biofunctional components very firmly. This entrapping method can be used not only for the immobilization of enzymes but also for the controlled slow release of drugs. Among these drugs, the antibiotics may be the most important ones to be employed. The process makes it possible to give the antibiotics a durable effect and prevents harmful side reactions. In this report, the radiation polymerization method is applied to the controlled release of antibiotics by the preparation of polymer composites which include antibiotics.
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  • 70
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    Journal of Biomedical Materials Research 14 (1980), S. 239-250 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The merits of a butt joint versus a bevelled margin are reexamined. It is shown that only acute bevels are effective in reducing the marginal diffusion of plaque acid. However, acute gold bevels may give rise to other major problems in avoiding distortion of the gold during firing of the porcelain, and finishing and cementing the crown.
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  • 71
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    Journal of Biomedical Materials Research 14 (1980), S. 311-324 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polymethyl methacrylate bone cement is tested at the Institute of Fracture and Solid Mechanics Laboratory, Lehigh University. Standard tensile coupon and compact tension specimens are molded under varying conditions of temperature and pressure. Test results are obtained for the strength and toughness of bone cement involved in total hip replacement operations.
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  • 72
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    Journal of Biomedical Materials Research 14 (1980), S. 341-341 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 73
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    Journal of Biomedical Materials Research 14 (1980), S. 383-391 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The flow properties of several major types of dental cements were investigated using slow compressive strength and creep techniques. Considerable differences were found in their behavior. Whereas the phosphate-bonded and glass-ionomer cements exhibited brittle fracture, the other cements tended to distort to a greater or lesser extent under load. All cements showed some creep under load but the extent of this varied considerably: the creep of phosphate-bonded cements being very small and that of the eugenol and related cements considerable.
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  • 74
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    Journal of Biomedical Materials Research 14 (1980), S. 405-415 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous samples of cellulose diacetate/nitrate CAN (millipore filter), polycarbonate PC (nuclepore filter), cellulose diacetate CA, and polydimethyl siloxane SR of various pore sizes were immersed in stirred heparinzied human blood while being perfused with lactated Ringer's solution at variours rates. Control samples were exposed to the blood in the absence of perfusion. The control tests showed that CAN and PC adhered platelets rapidly to plateau levels of 1-5 × 106/cm2 in ∼ 4 min, while CA and SR remained platelet-free. The critical perfusion rate, vp* to prevent adhesion of platelets (and all formed elements) to the CAN and PC was ∼0.1 cc/min cm2 at a shear rate of ∼620 sec-1 independent of pore size tested. vp* increased slightly with stirring rate. A simplified diffusion-convection model was used to qualitatively account for the effects observed.
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    Journal of Biomedical Materials Research 14 (1980), S. 41-53 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previous studies have suggested that one general type of osteon exists, rather than the three types previously classified as light, intermediate, and dark. A method is presented that permits rapid, quantitative measurement of the percent transmission of osteons seen in thin section between crossed polarizers. In studies of osteon segments from human cortical bone, cut either 200 or 5 μm in length, a continuous variation of transmission is seen, both for the populations as a whole and for serial sections. These variations cannot be ascribed to angulation between the direction of observation and the axis of the osteonal segment. No correlation can be observed between the angle of the segment axis and the percent transmission. It is suggested that the collagen fiber orientation in osteonal segments must be considered to be continuous, as judged by scattering of polarized light.
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    Journal of Biomedical Materials Research 14 (1980) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 77
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A two-dimensional finite element model (FEM) was used to investigate the effect of various prosthesis design parameters on stresses along the proximal medial aspect of the femur. Strain calculations were compared to reported experimentally measured strains for an intact femur and femur containing a prosthesis in an effort to verify the FEM results. The results of the study indicated that stress levels in the medical aspect of the femur approaching those of the intact femur are possible with a device having an elastic modulus similar to bone. It was found that acrylic bone cement had little effect on stress profiles in the medial aspect when compared to stresses for devices utilizing a direct bone to implant attachment mechanism. It was also found that reduction in implant stem length and elastic modulus of tissue present at the prosthesisbone interface could be used to increase stresses in the medial aspect; however, their effects were not as dramatic as reducing the elastic modulus of the stem material.
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  • 78
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    Journal of Biomedical Materials Research 14 (1980), S. 155-160 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This is the first of a series of presentations which we will publish irregularly. This new dimension in the literature will be of considerable interest to the many academicians involved in the teaching of biomedical sciences. - Ed.
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  • 79
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    Journal of Biomedical Materials Research 14 (1980) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 80
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    Journal of Biomedical Materials Research 14 (1980), S. 199-210 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The immobilization of some medically useful enzymes were studied by means of radiation-induced polymerization at -78°C. Glucose oxidase and glucose peroxidase were immobilized in the form of thin membranes inside polyvinyl chloride tubes and on polyethylene films; these membranes showed considerable activity yield, as well as good activity retention. Two effective methods were adopted to improve the surface properties of the base materials and to facilitate firm immobilization by coating: that is, an undercoating method followed by radiation curing of the undercoating and an irradiation grafting method with a monomer. Both were tested with good results. An immobilization of urokinase was also carried out successfully by similar methods. The thrombogenicity of the immobilized urokinase showed a remarkable effect on thrombus formation.
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A piezoelectric ceramic has been investigated as a direct substitute for hard tissues. Barium titanate (BaTiO3) powder was slipcast and fired at 1430°C for 2 hr, then made piezoelectric by polarizing. After 16 and 86 days of implantation in the cortex of the femoral midshafts, the femora with test specimens were sectioned into about 4-cm lengths. Their voltage outputs were measured under cyclic load at 1 Hz. The present results show that the voltage gradient at the implant surface is 0.15 mV/mm for the 16-day implantation with a 445-N (100-lbs.) load. This in turn can give rise to about 0.01 μA current flow in the adjacent area of the 16-day implant. The 86-day implant showed an order of magnitude higher voltage output compared to the 16-day implant with the same magnitude of loads. This is probably due to the “load-transfer” efficiency through the implants, since the voltage output is directly proportional to the actual load transferred to the implant. The more bone implant interface matures, the better the load transfer occurs through the implant, resulting in higher voltage output.
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  • 82
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    Journal of Biomedical Materials Research 14 (1980), S. 325-327 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 83
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    Journal of Biomedical Materials Research 14 (1980), S. 343-357 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Results from 197 subcutaneous implants on rats and 40 on mice of three different dental biomaterials were studied with emphasis on methodological evaluations. The types of implants employed allowed a differentiation between the materials based on the tissue reactions induced, but the degree of response recorded depended on the technique and the animal employed. The main problems encountered were the effect of operative trauma in short-term experiments, loss of material/tissue interface, dislodgement or tearing of sections if the materials remained in situ, folding and distortion of tissue, and difficulties in orientation of specimens for sectioning. The tube implant supplied with a window and sectioned perpendicularly on the long axis of the tube gave the least methodological problems. This “window technique” is therefore recommended as the method of choice for subcutaneous implantations. Cell density evaluations allowed quantitative determinations of the cellular response.
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    Journal of Biomedical Materials Research 14 (1980), S. 417-426 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An apparatus is described which permitted a perfusant (lactated Ringer's solution) to be passed through a porous sample in a pulsatile manner with a square wave pressure profile. The “on” time, “off” time, number of cycles and pressure amplitude were separately controllable. Using this apparatus and immersing the sample in stirred, heparinized, human blood, there was a certain “off” time below which platelet adhesion to the sample abruptly ceased. The values of this “off” time, termed the activation time ta for platelet adhesion were ∼0.5 sec for 0.2 μm pore size cellulose diacetate/nitrate (millipore filter) and ˜0.3 sec for 0.2 μm polycarbonate (nuclepore filter). After a single cycle with a 5 sec “off” time, adhered platelets on both these materials showed pseudopodia, varying degrees of spreading and membrane perforation.
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  • 85
    Publication Date: 1980-01-04
    Description: In concentrates of water produced in a laboratory simulation of a drinking water treatment process, direct-acting, nonvolatile mutagens were readily detected by means of the Ames Salmonella test. The mutagens were shown to be produced by the chlorination process. Treatment of the water with chloramine resulted in less mutagenic activity than treatment with free chlorine. Dechlorination of drinking water with sulfite sharply reduced the mutagenic activity. Treatment with sulfur dioxide is proposed as an effective, inexpensive method of reducing the direct-acting mutagenic activity of drinking water and of aqueous industrial effluents.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cheh, A M -- Skochdopole, J -- Koski, P -- Cole, L -- New York, N.Y. -- Science. 1980 Jan 4;207(4426):90-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6985746" target="_blank"〉PubMed〈/a〉
    Keywords: Chemical Phenomena ; Chemistry ; Chloramines ; Chlorine ; Mutagens/*analysis ; Salmonella typhimurium/genetics ; Sulfites ; Water Pollutants/*analysis ; Water Pollutants, Chemical/*analysis ; Water Supply/*analysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 86
    Publication Date: 1980-10-01
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bumb, R R -- Crummett, W B -- Cutie, S S -- Gledhill, J R -- Hummel, R H -- Kagel, R O -- Lamparski, L L -- Luoma, E V -- Miller, D L -- Nestrick, T J -- Shadoff, L A -- Stehl, R H -- Woods, J S -- New York, N.Y. -- Science. 1980 Oct;210(4468):385-90.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6159682" target="_blank"〉PubMed〈/a〉
    Keywords: Air Pollutants/analysis ; Chemical Phenomena ; Chemistry ; Chromatography, High Pressure Liquid ; *Dioxins/analysis ; *Fires ; Power Plants ; Smoke/analysis ; Soil Pollutants/analysis ; Tetrachlorodibenzodioxin/analysis ; Vehicle Emissions/analysis ; Water Pollutants, Chemical/analysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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