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  • Articles  (784)
  • Polymer and Materials Science  (784)
  • 1985-1989  (636)
  • 1965-1969  (148)
  • Medicine  (784)
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  • Energy, Environment Protection, Nuclear Power Engineering
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  • Articles  (784)
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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 1-2 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 2
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 3
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 11-16 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Methyl α-cyanoacrylate, when implanted subcutaneously in rats and dogs, has been shown to lead to an increase in thiocyanate output in the urine, presumably through the formation of cyanide anions which are subsequently converted to thiocyanate. It is postulated that this reaction may be one of the reactions contributing to tissue necrosis when methyl α-cyanoacrylate is used as a tissue adhesive.
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  • 4
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 3-9 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In an effort to obtain tissue adhesive monomers which would wet and spread on tissue substrates and be rapidly biodegradable, the branched esters of alkyl α-cyanoacrylates, as well as a 95-5 wt.-% mixture of n-heptyl and methyl α-cyanoacrylate, were studied. The data indicate that alkyl α-cyanoacrylates having branched alkoxy groups appear to be promising in this regard.
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  • 5
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 27-31 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A theory for the behavior of anodes as stimulus electrodes, particularly as pacemaker electrodes, is presented. Expressions are obtained for the minimum duration and energy of the stimulus. These expressions are applied to that for the dissolution of the anode and transport of the resulting ions in the tissue in order to obtain an estimate of the extent of penetration. Comparison with experimental data indicates good agreement.
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  • 6
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: New dialysis membranes, prepared from linear block copolymers, have shown unique separation properties which appear to be based on definite solute-membrane interaction. The synthesis and characterization of block copolyetherurethanes based on poly (oxyethylene glycol) is described.
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  • 7
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 33-54 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Currently available materials for mechanical heart systems are surveyed, particularly with respect to long-term implantation, from the viewpoints of availability and workability, mechanical and biological durability, and compatibility with blood and tissue. Some materials have one or more desirable physical properties, but none offers perfect blood and tissue compatibility. Medical grade Silastic, considered best for blood handling parts, has produced promising results in auxiliary ventricle patency experiments. The insufficient tensile strength of Silastic should be increased, and it may be possible to accomplish this while maintaining the present resilience, elongation, and inertness. No long-term data on thrombus formation are available, but clot-retarding quality is essential and may perhaps be obtained by incorporating heparin. Developments in polymer chemistry may also lead to other surfaces with the requisite mechanical properties with blood.
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  • 8
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Seven surgical adhesives were prepared; n-butyl, 2-ethylhexyl, and isopropyl cyanoacrylate monomers and several combinations of ethyl cyanoacrylate and a plasticizer (either di-2-ethylhexyl phthalate or tricresyl phosphate). These were implanted as a thin film over the entire circumference of the adventitia of 48 canine carotid arteries. Vicissitude of cyanoacrylate polymers in vivo and tissue reaction to the polymers were traced for 6 months and investigated histologically. All adhesives tested in this study were insoluble in vivo and more resistant to biodegradation than methyl cyanoacrylate polymer. Tissue reaction against n-butyl, 2-ethylhexyl, or isopropyl cyanoacrylate was essentially the same as against ethyl cyanoacrylate in quality and was not less in degree than ethyl cyanoacrylate in spite of having longer side chains than ethyl radical.
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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: Evidence is presented for the view that intravascular thrombosis proceeds via an electrochemical mechanism. It is strongly substantiated by some recent work on electrical wire thrombosis. These experiments show that thrombosis occurs on noble metal electrodes at potentials more positive than 0.3 v (NHE) but tends not to occur on electrodes more negative than this interfacial potential. Further, the same factors which prevent intravascular thrombosis are shown to prevent thrombosis on electrodes maintained at all potentials up to + 1.0v. Thus occurrence or prevention of thrombosis appears related to electrical and electrochemical properties of both blood and blood vessel wall. Methods for the determination of these properties are described and experimental results briefly presented. The studies have proved useful in establishing criteria for the selection of metal and plastic vascular substitutes. A combination of several electrochemical and biophysical criteria have been discovered which aid in the selection of nonthrombogenic vascular substitutes. Unfortunately not all metals which satisfy anti-thrombotic electrochemical criteria are suitable. Many, including magnesium, have cellular and proteolytic destructive characteristics. Certain metals and electrically treated Teflon tubes do not suffer from this defect and have proven useful in preliminary testing.
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  • 10
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A major part of current effort in improving artificial hemodialysis techniques concerns the development of improved membrane structures. Although blood compatibility of membranes is a part of the Battelle program, this discussion is confined to membrane composition, structure, and transport. On the basis of a need for improved hemodialysis techniques, membranes for use in the artificial kidney were prepared and evaluated for urea, creatinine, and uric acid permeability. Water-soluble polymers were crosslinked to form insoluble, but swellable, membranes. Faster metabolic waste transfer than with the conventional cellulosic membranes was obtained with diisocyanate-crosslinked poly (vinyl pyrrolidone) and poly (vinyl pyrrolidone)-dextran membranes and with membranes obtained by crosslinking poly (vinyl alcohol) with polyfunctional aldehydes. Membranes prepared from emulsions of vinyl pyrrolidone-ethyl acrylate and vinyl pyrrolidone-styrene copolymers had exceptionally high urea and creatinine dialysis rates, but were deficient in uric acid transfer. This shortcoming was corrected by incorporating solutes such as sucrose into the membranes followed by leaching. Another important approach concerned the development of a relatively high-strength membrane based on an impermeable nylon resin. Permeability of these membranes which have dialysis characteristics superior to those currently used was obtained through the addition of DMSO and one of several other additives to the coating solution.
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  • 11
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The tissue reaction to metallic and nonmetallic implants in the back muscles of New Zealand White Rabbits is presented. These reactions are graded and correlated with the trace metal contained around such implanes. Correlations are drawn as to the acceptability of various materials for the manufacture of surgical implants.
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  • 12
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 103-112 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The pressure losses in the currently available prostheses are too high. We believe an excellent way to focus designers' attention upon this fact is to rank the various designs according to their hydraulic efficiency. The proposal of this paper is for pressure drop vs. velocity data (pulsatile flow) to be taken similar to that of Figure 2, so that a pressure loss coefficient, Kv, based upon the valve lumen area can be found for each valve design; further, that this Kv be used to compare and rank the various valve designs. The fact that Kv is a dynamic loss coefficient guides designers toward its improvement, for this compares the prosthesis problem to many “solved” problems (propeller blade profiles, hydrofoil profiles, etc.) which are similar hydraulically. The confusion of the surgeon when confronted with conflicting claims regarding various prostheses would be largely eliminated by acceptance of Kv as a figure of hydraulic merit by those concerned with this aspect of biomedical engineering.
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  • 13
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 171-174 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The problems with the experimental and clinical assessment of arterial prosthetic materals vary from species-transfer of data to vested interests once an implantale device has been perfected for human trail. In spite of all the problems which arise, there has been a steady increase in our knowledge of the basic healing pattern of implanted arterial prostheses and the elaboration of specific paths for improvement of prosthetic design. Further development will be linked closely to the active participation of the biomedical researcher in areas of biophysical and bioengineering investigations.
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  • 14
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 113-134 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Semicrystalline polymers used as restorative prostheses in the cardiovascular system require more detailed consideration of flexural fatiguing with simple physical characterization and mechanical measurements as one basic means for developing test standards and specification levels for biomedical research materials. Such initial means are considered with polytetrafluoroethylene as a reference polymer nominally inert chemically used to illustrate one approach to assessing morphological and structural changes with a flex tester. Density measurements and void content have been carried out to provide one means of assessment whereby the corresponding crystallinity and permeation can be considered for more detailed correlation to cytological interactions as the polymers are used as replacement components in the cardiovascular system. Progressive flexural cycling up to 106 cycles at a 3 cps rate indicate significant decreases in crystallinity simultaneously with increasing void content. As an accelerated test, the implications for extrapolation to 25-year fatiguing in normal physiological cycling rate are conjectured to provide a starting point for more realistic, cyclic ex vivo screening of biomaterials.
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  • 15
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 175-175 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 16
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 175-175 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 17
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 18
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 176-176 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 19
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The clotting problem inside the artificial heart device is one of the major obstacles standing in the way of a successful long-term implantation of the artificial heart. To date, there have been two artificial heart devices used clinically. One is the auxiliary ventricle and the other is the left heart bypass pump. The former is for permanent implantation and the other is implanted only temporarily. Several experimental results which had contributed to the successful implantation of the auxiliary ventricle are described, especially from the standpoint of avoiding the clotting inside the device. Basic experiments with the left heart bypass pump are also described. The valves are the foremost problem and the next is the junction of the two materials. It is ideal to have a smooth, seamless surface made entirely of one material. It is also necessary to have a flow pattern analysis inside the artificial heart device as well as a clotting pattern analysis. Since the pump oxygenator and heparinization are involved in the procedure, the clotting problems in the total heart experiment are usually less than in the left heart bypass experiments. Our most urgent requirement is the development of new antithrombogenic material. However, even with our present material a large part of the clotting could be avoided if the heart is carefully constructed.
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  • 20
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 1 (1967), S. 179-196 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Warp-knitted velour fabrics of Dacron, nylon, polypropylene, and Rayon have been backed with Silastic to form a laminate. Prior to heat curing, the composite can be molded into many shapes and has been successfully used to line the luminal side of blood pumps and vascular grafts. Prosthetic heart valves are being covered with velour in an attempt to promote a more compatible surface. Velour suture rings are being evaluated as a more efficient anchor for prosthetic heart valves. Silastic tubes with velour bonded to the outer wall have been used to inhibit infection and sinus tract formation where percutaneous lead wires and conduits are necessary. As a flat sheet, the Silastic-velour laminate has been used experimentally as an artificial skin, but the most noteworthy experimental results have been obtained in rats using a double layer of nylon velour, separated by an impermeable layer of poly(vinyl fluoride). Future application will include attempts to anchor artificial limbs via a velour interface and made functional by tendinous attachment.
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  • 21
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Inhibition of cultured mammalian cell growth was used to examine the biological activity of triethyl citrate, a common plasticizer for poly(vinyl chloride). Cell populations were determined by a sample extraction procedure and measurement of nucleic acid content (total purines and pyrimidines) by its absorbance at 268 mm̈. Triethyl citrate demonstrated strikingly different dose-effect characteristics from its theoretical hydrolysis products (ethanol and citric acid). The inhibitory effects of sodium citrate were reversed by calcium chloride while the action of triethyl citrate underwent little or no change under similar conditions. Triethyl citrate did not appear to produce resistant cell strains in culture but did seem to be degraded with time. Inhibitory action of triethyl citrate was shown to be independent of inoculum size within the ranges utilized in the study. The procedures described appear to have a number of advantages for the biological or toxicological evaluation of ingredients which might be added to a plastic formulation or to contaminates which might enter the plastic during manufacture of the item or device.
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  • 22
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of studies were performed using S35-labeled heparin to determine the amount and the permanancy of heparin grafted onto nonthrombogenic surfaces. The calculated thicknesses of the heparin layers (based on geometrical areas) ranged from 100 to 1500 A. It was shown that the surface having a 100-A layer of attached heparin was nonthrombogenic. The stability of the heparin attached to polypropylene, silicone rubber, hydrin rubber, and graphite-benzalkonium-heparin (GBH) surfaces in distilled water, isotonic saline, and human plasma was measured. The results showed that after exposure to water and saline, the first three surfaces retained most of the attached heparin (〉90%) in contrast to the GBH surface which retained only 31%. After contact with human plasma for 3 hr at 37°C, polypropylene retained 32% and GBH surfaces 19% of the heparin which was initially present. In another series of experiments, the adsorption of P32-labeled proteins onto unheparinized, quaternary ammonium, and heparinized surfaces was measured. The results indicated that the amounts of albumin, Hageman factor, thrombin, and γ-globulin adsorbed onto heparinized surfaces were equal to or greater than the amounts adsorbed onto unheparinized surfaces. The implications of this in terms of the nonthrombogenicity of the heparinized surfaces are discussed.
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  • 23
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    Journal of Biomedical Materials Research 1 (1967), S. 213-238 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: 1. With the help of ionotropic gels it is possible to duplicate native structures consisting of two materials, one of them the matrix. 2. Counter-ions combined with the ionic groups on the ordered polyelectrolytes can be exchanged. With certain counter-ions an insoluble, crystalline precipitate is formed immediately after the ion-exchange process as an ordered reaction product, i.e., nucleation. 3. Ionotropic gels were crosslinked through the secondary hydroxyl groups (uronic acid residuals) in such a way that the rate of ion exchange was only slightly lower, that no great shrinkage resulted, and that the pores remained free of extraneous polymers. 4. The microscopic structure of ionotropic gels can be divided into (a) a part with secondary structure with micellar particles and hollow pores and (b) a part with tertiary structure with lamellae and isopores. 5. On crystallization in shrunken gels the crystals enter into the tertiary structure - both intracapillary as well as interlamellar - due to spatial reasons. 6. Through control of the shrinkage of the gels, one can regulate the way in which the ordered crystals enter into the two structures. 7. One can change the size of the crystallites by variation of the degree of crosslinking. The higher the degree of crosslinking, the smaller the crystallite. 8. By treatment with waves of ions one can increase the solid content of the gel to values from 50 to 70%. One obtains gels with a mechanical strength like that of bones, teeth, shells, or pearls. The phenomenon of intramicellar crystallization is reversible. Monovalent counter-ions, as well as H-ions, dissolve and extract the included secondary substance. One then obtains the original crosslinked gel. 10. The gel has always to be formed first. Without the ordered base structure (matrix) one obtains unordered crystallites such as occur in the chalklike fields of the pearl shells.
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  • 24
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    Journal of Biomedical Materials Research 1 (1967), S. 253-261 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous laminates prepared by incorporating a volatile solvent into an epoxy resin system used to impregnate a fabric filler satisfactorily alleviated the problems caused by perspiration in upper extremity prostheses, but did not have sufficient strength for use in artificial legs. A new technique is described which results in a 100% increase in both porosity and strength of porous epoxy laminates. The method consists of impregnation of the fabric with resin and solvent and evaporation of the solvent prior to laying up the laminate. The improvement in properties is ascribed to better control and homogeneity of impregnation.
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  • 25
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    Journal of Biomedical Materials Research 1 (1967), S. 275-284 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A design theory is developed for a compact artificial kidney utilizing microcapsules containing urease, ion exchange resin, and adsorbents for uric acid and creatinine. It is shown that the critical factor is the permeability property of the microcapsule wall and that an artificial kidney 10 cm in length and 2 cm in diameter is feasible.
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  • 26
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    Journal of Biomedical Materials Research 1 (1967), S. 285-297 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Samples of (Ag + Hg) amalgam and of dental amalgam have been prepared and stored at temperatures of 23, 37.5, and 60°C for various lengths of time up to 10 years. X-ray diffraction and optical microscopy have been employed to determine the approximate increase in the β(Ag—Hg) phase as a result of the γ → β transition in the Ag—Hg system. Data are presented to show that the transition occurs in both systems but much less rapidly in dental amalgam. Increases in storage temperature increase the rate of the transition in both systems.
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  • 27
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Strains were determined in a typical mandibular partial denture metal framework of the free-end saddle type. The overall strain patterns were determined using a brittle lacquer coating technique and loads were applied vertically to positions on the saddles. The results from the coating study indicated the area of high strain were just anterior and posterior to the finishing lines. Strain gages were attached to positions anterior and posterior to the finishing lines and the strain was measured at these positions when the saddles were loaded either at a posterior or anterior position at intervals of 2 lb up to 20 lb. When a static load of 20 lb was applied to the posterior of the left saddle a strain of 750 μ in./in. was obtained, which for the alloy used was equivalent to a stress of 22,200 lb/in.2. The amount of strain observed was a function of the length of the saddle, the bulk of the framework, the relation of the site of the gage to the position of loading, the presence of an indirect retainer, and the position of the fulcrum for the loading conditions used.
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  • 28
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    Journal of Biomedical Materials Research 1 (1967), S. 299-299 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 29
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    Journal of Biomedical Materials Research 1 (1967) 
    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 1 (1967), S. 301-312 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The present paper describes a new technique for preparing the surface of polyethylene and polypropylene plastics for the adsorption of heparin. The procedure consists of exposing the plastic surface to a solution of cationic surfactants at a temperature close to the softening temperature of the plastic. The mechanism of adsorption of the anticoagulant of the surfaces is discussed.
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  • 31
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    Journal of Biomedical Materials Research 1 (1967), S. 325-336 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In 14 canines the ureter was substituted with a new type of ureteral gel-fabric prosthesis. The prosthesis is a tube of knitted fabric of polyester fiber case in a layer of hydrophilous glycol methacrylate gel. Anastomoses were carried out by inserting the prosthesis ends into the ureter lumen and by suturing the stump of the ureter to a special fixing ring on the prosthesis. Preliminary results of short-term obsevations (4 months) are quite promising. The prosthesis is non-irritating and conducts the urine satisfactorily.
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  • 32
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    Journal of Biomedical Materials Research 1 (1967), S. 313-323 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biologic properties of the sponge-like polymers of ethylene glycol methacrylate gels and their host compatibility have been verified in subcutaneous and intraperitoneal application in rats. All three sample types tested, with different porosities, have been tolerated very well with the receptor and have caused no pathologic reaction. Subcutaneous implants are directly integrated in teh organism, cellular immigration taking place with vascularization of the surface layer of the implantate to a depth of some 500 μ during the second week after implantation, causing the sponge to become an integral component of the surrounding tissues. More substantial differences in the reaction to the presence of implantates of different porosity ahve not been observed. These properties directly predetermine the sponge-like polymers for wider application in plastic and reconstructive surgery. In addition, there is the possibility of utilizing them as an auxiliary surgical material, e.g., for drying and cleaning the operative field, or as operation towels. Good results have been achieved also in mechanically stopping bleeding from parenchymatose organs by application of the sponge foil.
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  • 33
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    Journal of Biomedical Materials Research 1 (1967), S. 337-354 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Features controlling the initiation of matrix calcification have been investigated in a model system. Two major influences which dominate nucleation are the matrix integrity and the location of certain chemical binding sites. It has been shown that chemical chelating groups can, and do, promote calcification under simulated physiological conditions. Organically bound phosphate does not appear to promote nucleation, suggesting that it is chelation of calcium or other cations which is the initial step in tissue calcification. In the sequence of compounds investigated for nucleation catalysis, those possessing at least three chelating groups and a stereopsecific configuration were effective. The mineral phase forming first in association with the organic matrix is a soft non-apatitic calcium phosphate of Ca/P ratio approximately 1.5. This is the same phase that forms in the absence of organic matrices at physiological pH and is probably the precursor to hydroxyapatite in biological calcification. It is suggested that nucleation catalysts exist both within and outside the collagen fibrillar framework. A possible location of the internal site has been proposed, based on the availability of a capillary channel and chelating ligands, and this postulate is supported by electron microscopic evidence which shows that bone crystals lie within the fibrils, occupying space which terminates in the polar 640 A staining area.
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    Journal of Biomedical Materials Research 1 (1967), S. 369-369 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
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  • 35
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    Journal of Biomedical Materials Research 1 (1967) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
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  • 36
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Knowledge of the characteristics of the blood-intima interface is important because it leads to information concerning (a) the normal antithrombotic mechanism (b) nature of interreactions between blood and intima (c) testing and selection of vascular wall substitutes which are antithrombotic and inhibit clotting. A technique for obtaining the electrical interfacial characteristics of blood vessel walls is by measuring streaming potentials. Experiments described in the present work are extensions of original in vivo streaming potential measurements. In vitro streaming potentials were measured across fresh canine aortae and carotid arteries using Krebs saline serum substitute, logarithmically varying both internal and external electrolyte concentrations. Positive streaming potentials were measured indicating that the blood vessel wall is negatively charged. Streaming potentials increased linearly with increasing flow rate, decreased with increasing internal electrolyte concentration, decreased with increasing external electrolyte concentration, and reversed, becoming positive, with aging of exteriorized artery. Thus the electrical characteristics of the blood vessel wall are dependent on an ionic balance between the blood vessel wall, flowing blood stream, and external environment. The information demonstrates the importance of electrochemical and physicochemical phenomena in the structure and function of the vascular interface and helps explain in vivo conditions conducive to or inhibitory of intravascular thrombosis.
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  • 37
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    Journal of Biomedical Materials Research 1 (1967), S. 387-394 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The authors followed the tissue response of a new plastic tube composed of neutral hydrophilic gel, after implantation in the subcutis of rats. They further studied tissue reaction when gel rods were connected by polymerization in situ. After implantation, the gel tubes developed a fine encapsulation but no inflammatory response. The gel rods were connected “end to end” by means of a drop of the polymerizing mixture. The healing proceeded in the same manner with the exception that minute granules of macrocellular elements were formed in the ligament surrounding the polymerization mixture remnats. According to these results, the neutral hydrophilic gel has proved to be a suitable material for implantation.
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  • 38
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    Journal of Biomedical Materials Research 1 (1967), S. 371-386 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new intraoral adhesive bandage composed of gelatin, sodium carboxymethylcellulose, and polyisobutylene backed by a layer of polyethylene film was used by 148 investigators in 1468 patients. The bandage adhered well to the fixed mucosa of the palate, gingiva, and teeth. It adhered less satisfactorily to the loose mucosa of the cheek and floor of the mouth. It did not adhere very well to the tongue. The duration of adhesion of the bandage was at least 5 hr in approximately 87% of all treated cases, and it remained in place for 9-51 hr for more than 50% of all treated patients. Tolerance of the application was good or excellent in 75% of all cases. There was no irritation attributable to the bandage in any patient. The bandage provided an effective means of protecting the vital repair mechanism of a wound during the early hours after extraction. The results of these trials indicate that the new adhesive bandage is safe and that it provides effective cover and protection of wounds and lesions of the mucous surface up to 24 hr.
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  • 39
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    Journal of Biomedical Materials Research 1 (1967), S. 395-404 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Sutured, stapled, and methyl- or thickened n-pentyl-2-cyanoacrylate-adhered end-to-end arterial anastomoses were compared in two series of 10 dogs, employing the three 4-mm diameter terminal branches of the aorta for these comparisons. Patency rate, speed of construction, and gross and microscopic appearances were employed as criteria for evaluation. In a series of adult white rabbits the same criteria were applied to compare sutured and thickened n-pentyl-2-cyanoacrylateadhered end-to-end anastomoses of the 2-mm diameter abdominal aorta. Anastomoses adhered with methyl-2-cyanoacrylate were significantly more often thrombosed than any other variety; a marked inflammatory response followed application of this material. Thickened n-pentyl-2-cyanoacrylate adhesive was well tolerated, and the results obtained with this material were equivalent to those obtained by suturing or stapling in the dog, or by suturing in the rabbit.
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    Journal of Biomedical Materials Research 1 (1967), S. 405-414 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Corrosion resistance is particularly important in medical treatments requiring implantation of metallic objects in the human body. Unfortunately, weight loss measurements and other conventional corrosion testing techniques are insufficiently sensitive and difficult to adapt to in vivo environments. The linear polarization technique can be used to remotely meaure the corrosion rates of metals implanted in tissue using needle probes. The principles of this technique are reviewed and the results of tests performed on steel, cobalt, and molybdenum implanted in experimental animals are discussed.
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  • 41
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    Journal of Biomedical Materials Research 1 (1967), S. 415-425 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The presence of the β1 phase in dental amalgam after 60°C heating has been confirmed by x-ray diffraction, metallography, microhardness tests, and electron beam analysis. It appeared that the γ1 → β1 transformation began at preferred sites, believed to be possibly areas deficient in Hg, and grew outward from these sites. Even after heating for nearly a year, however, some γ1 still remained in the sample.
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  • 42
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    Journal of Biomedical Materials Research 2 (1968) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
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  • 43
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    Journal of Biomedical Materials Research 1 (1967), S. 427-432 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In vivo and in vitro experiments described herein have demonstrated that the GBH coating is antithrombogenic when placed on PVC, as tested in the blood system of rabbits for periods up to 2 weeks. In vitro clotting times cannot be correlated with the in vivo thrombogenicity of the same implants. For example, dog and man have very similar in vitro clotting times, but very dissimilar in vivo prosthetic thrombosis problems. In vivo and in vitro tests are for the most part not comparable in that they do not measure the same things. However, both in vivo and in vitro tests proved the GBH-treated vinyl to be antithrombogenic. It may be concluded from the available data that a flexible plastic can be treated with GBH and become antithrombogenic for a practicable period of time.
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    Journal of Biomedical Materials Research 1 (1967), S. 433-449 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Man-made polymeric materials are being utilized in a number of devices which will be implanted into animals and humans for various periods of time. The diversity of materials and the introduction of new materials into the medical and paramedical professions appear to be increasing at an accelerated rate each year. Even though great advancements have been made by the biomedical engineer and the surgeon in designing and implanting a prosthetic device in the body, less emphasis apparently has been given to the possible or potential hazardous aspects of the material. An implantable material may initiate a body response in two general ways: (1) release of an ingredient from the material to the biological environment and (2) alteration of the material by the biological environment, leading to degradation of the material with its various consequences. If serious future hazards are to be kept to a minimum, greater emphasis must be placed on well-designed toxicity studies of materials which, in turn, could lead to standardized materials for implants.
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    Journal of Biomedical Materials Research 2 (1968), S. 1-22 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Several metallic orthopedic implants which failed in service and for which the medical histories are known are comprehensively examined using metallographic techniques and electron microprobe analyses to determine the causes of failure. The results indicate that fatigue is a major cause of failure and that, in all probability, the fatigue is initiated by poor design or poor material.
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    Journal of Biomedical Materials Research 2 (1968), S. 43-49 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Tubing made of a polar plastic, polychlorotrifluoroethylene, was electrically polarized while heated. The zeta potential of tubes polarized negatively inside was consistently higher than that of unpolarized tubes. Tubes polarized positively had a much smaller and variable change in zeta potential. The change is apparently not related to the formation of electrets, but may be due to the orientation of pre-existing dipoles.
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    Journal of Biomedical Materials Research 2 (1968), S. 23-42 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of phenol and certain phenyl compounds on the different stages of the blood coagulation and fibrinolytic mechanism is investigated. Phenol has a complex action on blood coagulation. In an optimal concentration of 0.3% it produced a definite, though suboptimal platelet factor 3 activity, evolved factor XII, accelerated thrombin-fibrinogen interaction, retarded clot retraction, enhanced the action of streptokinase on plasminogen, and inhibited plasmin. In addition, in the absence of factor XIII and calcium, it increased the solubility of fibrin in urea. Phenyl acetaldehyde, benzyl benzoate, and styrene (phenyl ethylene) accelerated stypven clotting time and thrombin-fibrinogen reaction. Unpolymerized styrene and phenyl ethanol specifically inhibited the action of plasma thromboplastin, formed in a system lacking in factor VIII or IX. A study is also reported on the changes responsible for the stabilization with phenol of brain thromboplastic activity. The action is not purely bactericidal, but is dependent on the presence of brain tissue particles in suspension. The contribution of platelets to plasma thromboplastin formation is examined in the light of these investigations, showing the ability of phosphorus-free compounds to supply a platelet-like activity.
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  • 48
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    Journal of Biomedical Materials Research 2 (1968), S. 81-88 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Adult albino rabbits were implanted with disks of 316 and 304 stainless steel in the subperiosteum of the anterior calvarium and the left mandible and in the left paravertebral and thigh muscles. The corresponding opposite sites were sham operated. The histopathological slides revealed that there was variation in thickness of the membrane in sections of both the paravertebral and thigh muscles; one side showing greater reaction than the other, which corresponded with the appearance of the implants. Sections of the calvarium revealed minimal bone and soft tissue reaction, although the implants showed corrosion compatible with soft tissue sites. The mandibular sections revealed extensive bone tissue reactions with minimum masseter muscle reactions, but the appearance of the implants due to corrosion was different than those of all other sites. Moderate eosinophilic infiltration was observed in sections containing deposits of corrosion products.
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    Journal of Biomedical Materials Research 2 (1968), S. 89-93 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: An alternate correlation of blood coagulation time with surface properties of solids is proposed in that the work of adhesion is used rather than the surface free energy. The overall quality of the two correlations is about the same, but the new method does allow the important data point for glass to also be included. Possible useful future work of this type is discussed.
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    Journal of Biomedical Materials Research 2 (1968), S. 51-79 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioelectric charge transfer at the blood-wall interface may be a crucial factor affecting thrombosis on implant materials. A program of studies was conducted to determine the electrokinetic and other physical properties of a wide spectrum of materials including organic polymers, metals, inorganics, heterogeneous compounds, and animal tissue. From these tests, materials were selected for in-vivo cannulation experiments. In this manner, a search was made to find a correlation between surface charge characteristics and thrombosis on cardiovascular implant materials. It was found that materials exhibiting a substantial positive charge were prone to rapid thrombosis. No clear correlation can be stated, as yet, regarding the thrombogenecity of highly charged negative surfaces or slightly charged surfaces. However, many heterogeneous materials have exhibited prolonged in-vivo patency. It appears necessary to isolate surface effects from volumetric effects to seek the role of bioelectric charge transfer in blood thrombus formation.
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    Journal of Biomedical Materials Research 2 (1968), S. 121-130 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A segmented polyurethane elastomer, originally developed for elastic thread, is now being used for molded prostheses. Chemical, mechanical, and biological properties are described. Hydrolytic stability of this polymer is compared to that of a polyester urethan. Experience with the material used in components of an experimental heart-assist pump has shown excellent flex endurance, wear resistance, and intravascular acceptability.
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    Journal of Biomedical Materials Research 2 (1968), S. 131-143 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: During the period covered by this investigation, toxicological studies were carried out in hamsters and rabbits. The results of injections, subcutaneously and in the buccal pouch of hamsters, indicated that the silicones used were nontoxic, non-absorbable, and well encapsulated by connective tissue elements with moderate tissue reaction. Further studies of various combinations of roomtemperature vulcanizing silastics indicated similar reactions when injected submucosally in the alveolar ridges and palate of rabbits. The injected materials remained in situ in the injected submucosal area and became well encapsulated by the proliferation of connective tissue and collagenous fibers. There was no evidence of macrophages or foreign body giant-cells in and around the proliferating connective tissue capsule. There were no macroscopic or microscopic signs of tumor formation. The encapsulated masses did not elicit bone resorption when localized adjacent to bone tissue.
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    Journal of Biomedical Materials Research 2 (1968), S. 95-119 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effects of variations in composition and processing on the open-circuit electrode potentials measured as a function of time of amalgams made from silver-tin, silver-tin-copper, silver-tin-zinc, and silver-tin-copper-zinc alloys have been determined at 37°C in distilled water, in saline solution, as well as in acetate and citrate solutions buffered to pH values of 3, 7, and 10. The electrochemical potentials of the alloys measured as a function of time in neutral acetate solutions show anodic polarization from an initial cathodic potential value of approximately 0.1 v with respect to the standard hydrogen electrode to a constant potential level depending upon alloy composition. In neutral acetate solution the potential-time curves of silver-tin amalgams with 7:5 mercury to alloy ratio show a rapid anodic polarization from an initial anodic potential value of 0.28 v to a minimum value of 0.05 v at approximately 1 hr followed by a potential reversal to a plateau value of 0.40 v. For 7:5 amalgams in neutral acetate solutions increases in both the trituration time and in the severity of processing deformation cause a small increase in initial potential, with a decrease in anodic polarization, while an increase in amalgam age lowers both the initial potential value and the longer-time potential plateau. Increasing the mercury content of the amalgam to a 2:1 ratio decreases the rate of potential reversal from the minimum, whereas decreasing the ratio to 4:5 decreases the amount of depolarization from the minimum value. The effects of copper and zinc additions to silver-tin alloys are mixed. In neutral acetate solution the 7:5 ratio amalgams from silver-tin-copper alloys show anodic polarization from the same initial value as the silver-tin amalgams, followed by a region of decreased polarization. Both silver-tin-zinc and silver-tin-copper-zinc alloys exhibit a much higher initial anodic potential (0.78 v), and following the achievement of the potential plateau have a slow anodic polarization to the long-time potential value shown by silver-tin amalgam. Three commercial alloy amalgams were studied in neutral acetate solution. The two amalgams containing zinc have a potential behavior similar to that of the experimental zinc-containing amalgam; the non-zinc amalgam shows a rapid anodic polarization from an initial anodic potential value of 0.24 v, a minimum at 1 hr, and a reversal to the long-time potential values of 0.40 v shown by the zinc-containing amalgam.
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    Journal of Biomedical Materials Research 2 (1968), S. 157-163 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Three monomers, β-14C-tagged methyl, n butyl, and n-heptyl α-cyanoacrylate, have been applied to intact skin and split-thickness skin-graft donor sites on rats. The data indicate that the urinary 14C activity is in the order: methyl 〉 n-butyl or n heptyl. Also, the urinary activity, when the monomers are applied to the split thickness skin graft donor sites, is approximately threefold greater than when the monomers are applied to intact skin. The conclusion is that the application of cyanoacrylate monomer to the skin is not only topical in nature, but may involve the internal milieu as well.
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    Journal of Biomedical Materials Research 2 (1968), S. 145-155 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyelectrolyte complexes are ionic hydrogels formed by the coreaction of two oppositely charged, strongly ionized polyelectrolytes. While insoluble in simple solvents and infusible, these polymers can be fabricated into membranes, fibers, and other shaped articles by casting from ternary solvents. Homogeneous membranes are optically clear, amorphous structures in which the equilibrium gel water content can be controllably varied from ca. 30-90%. The net ion-exchange capacity of the membrane can be varied from zero to ca. 2.0 meq/g, either cationic or anionic. Homogeneous membranes are characterized by unusually high water and gas permeabilities and permeabilities to water and soluble solutes which can be controlled by adjustment of gel water content and ion-exchange capacity. Anisotropic membranes can also be prepared which are high flux molecular ultrafilters for solutes as small as sucrose. The anisotropic membranes have found widespread use in biology for fractionation, concentration, and purification of biopolymers. Homogeneous membranes show promise as analogues for biological membranes. A number of applications are being evaluated in medicine and surgery. These include: vascular grafts, antithrom-bogenic coatings for plastic prostheses, contact lenses, corneal implants, and surgical adhesives. In addition, polyelectrolyte complex membranes are showing considerable promise for artificial kidneys and blood oxygenators.
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    Journal of Biomedical Materials Research 2 (1968), S. 165-171 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A quantitative method for determining residual ethylene oxide in plastic and rubber catheters using gas-liquid chromatography has been developed. Tests on ethylene oxide stabilized catheters indicated that the amount of ethylene oxide in the catheters decreased as a function of aeration time up to 48 hr. After this period, a steady concentration of ethylene oxide in the catheters appeared to have been reached up to one week's testing.
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    Journal of Biomedical Materials Research 2 (1968), S. 183-184 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 2 (1968) 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 2 (1968), S. 187-199 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A rapid mixing and sampling technique was used to study the permeability characteristics of semipermeable aqueous microcapsules (artificial cells). Urea, creatine, creatinine, uric acid, glucose, sucrose, and salicylic acid equilibrated rapidly across nylon microcapsules of 207 μ diameter (e.g., T 1/2 for urea of 3.4 sec). From these results the permeability constants were calculated (e.g., P for urea of 2 × 10-4 cm/sec). Very much the same permeability constants were found for collodion microcapsules. The equivalent pore radius of the membrane of the nylon microcapsules were estimated to be 18 A.
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    Journal of Biomedical Materials Research 2 (1968), S. 209-214 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The critical need for purchase specifications for implantable biomedical materials is the focus of this contribution. The elements in development of such specifications are presented with specific reference to a widely used high polymer, polytetrafluoroethylene. A specification for sheet or film of this plastic, as instituted by a major urban hospital, is presented in detail.
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Previous observations of pseudointimal organization within impermeable cardiovascular prostheses indicated that rapid spontaneous healing was dependent upon proximity of host vascular tissue at the suture line. Autologous connective tissue fragments were prepared from skeletal muscle biopsies by blender-mincing muscle tissue. The fragments were embedded in the fabric used to line the inner wall of arterial prostheses. A tightly fitting piston was drawn through the prosthesis, forcing the suspended tissue fragments to flow around the piston and become entwined in the loops of the velour fabric. The arterial prostheses prepared in this way were inserted as replacements for segments of canine abdominal aorta. This in vivo culture system supported cellular proliferation and pseudointimas healed uniformly. Pseudointimas of paracorporeal pumps in operation for as long as 5 weeks did not show signs of healing. The same principle of filtration of tissue fragments into a lining fabric was applied to diaphragms of left ventricular bypass pumps. This type of paracorporeal pump supported in vivo culture of implanted fragments.
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    Journal of Biomedical Materials Research 2 (1968), S. 215-230 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Maximum extraction stress and integrated extraction work were measured for sutures implanted for 3, 7, and 14 day periods. Six common non-absorbable sutures, representative of braided and monofilamentary forms, were implanted subdermally and were used for cutaneous incision closure with purebred pointer dogs. The data show: (1) Braided sutures, polyester/Teflon, silk-type B, and silk-silicone interacted with peripheral tissue to a significantly greater degree than the monofilamentary types, nylon, polypropylene, and polyethylene; (2) polyester-Teflon braided suture interacted to a lesser degree than the other braided sutures; (3) the relatively intense interaction of plain silk and silicone-treated silk appears to reflect the combined effects of mechanical aspects of braiding and of biochemical response; and (4) all braided sutures swelled over the implantation periods with as much as a 70% increase in diameter after 14 days for silk.
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    Journal of Biomedical Materials Research 2 (1968), S. 237-243 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A hydrophilic plastic material (USA trademark Hydron), developed by Wichterle and Lím, was used as a sponge for augmentation of breasts in the clinic for plastic surgery. The preparation of the prosthesis and the operational procedures are described.
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    Journal of Biomedical Materials Research 2 (1968), S. 231-235 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: ATP-diphosphohydrolase, trypsin, and chymotrypsin have been insolubilized by lattice-entrapment using hydrophilic polyacrylamide gel and hydrophobic Silastic matrices. The entrapped enzymes were stable and unaffected by washing or wet storage. Thermal inactivation properties of polyacrylamide-entrapped ATP-diphosphohydrolase were different from those of the same enzyme in solution. Several substrates were used for each of the proteolytic enzymes. Esterase activities of both trypsin and chymotrypsin were unaltered by entrapment within Silastic. The entrapment of enzymes and other active proteins is potentially of consequence in continuous-flow substrate conversion systems. Silastic with a surface proteolytic activity derived from an entrapped enzyme is of possible medical utility for implantation elements.
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    Journal of Biomedical Materials Research 2 (1968), S. 279-279 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A careful solvent-exchange procedure followed by liquid-phase reaction of ethyleneimine with cellulose film in a nonpolar solvent provides an effective method of uniformly aminoethylating cellulose. The protonated aminoethyl groups on the cellulose can then ionically bind heparin, a blood anticoagulant. Heparinized aminoethylated cellulose tubing at low levels of aminoethylation (ca. 0.2-0.3% nitrogen) exhibited excellent antithrombogenic properties as well as excellent mechanical strength properties. The in vitro tests demonstrated indefinitely long whole-blood clotting times with normal thrombin times. In the in vivo experiments, the heparinized aminoethylated cellulose tubing provided extended patency when implanted intravascularly in the regions of low blood flow rate (infra renal inferior vena cava of dogs). A principal use of this film is in the artificial kidney.
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    Journal of Biomedical Materials Research 19 (1985), S. 161-178 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The patency of heparin-polyvinyl alcohol (hep-PVA) coated polyethylene tubing was found to be significantly longer than control tubes coated with polyvinyl alcohol (PVA) but without heparin at low flow rates in dogs using a novel parallel flow arteriovenous shunt designed to avoid surgical artifacts. A standard Silastic chronic shunt (3.18 mm i.d.) was inserted between the iliac artery and vein of a dog. After a 2-week recovery period, a small diameter coated polyethylene tube (1.14 mm i.d.) was connected in parallel with the exteriorized portion of the chronic shunt through a pair of Silastic Y-connectors, so that 〈3% of the shunt flow was diverted into the test tube. The chronic shunt was reused many times over a 〉6 month patency period, eliminating the need for frequent surgery and reducing interanimal variability in the results. The difference in patency between heparinized and control tubes was greater at higher mainshunt flow rates indicating the presence of a significant effect of the Y-connectors on platelet adhesion or aggregation. This effect was manifested in a time-dependent reduction in circulating platelet count. Scanning electron microscopy (SEM) examination of the midportion of the heparinized tubes after occlusion demonstrated the absence of platelet and fibrin deposits, unlike the control tubes without heparin. Although the Y-connectors played a significant role, they did not dominate the thrombotic processes occurring in this shunt and consequently the biological effectiveness of the immobilized heparin could be demonstrated.
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    Journal of Biomedical Materials Research 19 (1985), S. 179-193 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As a series of studies on the mechanical properties of materials used in cardiac prostheses, static and dynamic characteristics and stability of five kinds of elastomeric polymers have been studied by uniaxial tensile and fatigue tests in air at room temperature and in saline solution at 37°C. Of all materials tested in this study, Texin MD85A, a segmented polyether polyurethane, has the lowest flexibility under static and dynamic conditions, with relatively high strength. Hexsyn, a polyolefin rubber, is highly flexible with little stress relaxation. However, this material has very low tensile strength and short elongation, and shows unstable change in the elastic modulus during cyclic deformation. Avcothane 51, a copolymer of polyurethane and silicon, has unstable mechanical properties and gradually stiffens upon cyclic deformation. On the other hand, Biomer, a segmented polyether polyurethane, has high flexibility and shows the most stable behavior during cyclic deformation regardless of test environment. Toyobo TM5, a similar segmented polyurethane to Biomer, has higher strength and ductility than Biomer, although its static and dynamic flexibility are slightly worse and less stable than those of Biomer. These results indicate that Biomer and Toyobo TM5 are more suitable for flexible components of cardiac prostheses.
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    Journal of Biomedical Materials Research 19 (1985), S. 197-198 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
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  • 70
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    Journal of Biomedical Materials Research 19 (1985), S. 241-250 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This is a review of the surface chemistry of bone mineral and its synthetic counterpart hydroxypapatite. Small-angle x-ray scattering and low-temperature nitrogen adsorption measurements show bone mineral surfaces range from 100 to 200 m2/g. The heats of adsorption of small molecules on bone and apatite surfaces show that these materials have polarizing surfaces which form strong bonds with polar and polarizable molecules. Water is hydrogen bonded to these surfaces with energies ranging from 23 Kcal/mol, for low coverage, to 11 Kcal/mol after two full layers; the latter value shows that after two monolayers the water is bonded as strongly to the solution as it is to the apatite surface. Stearic acid in cyclohexane adsorbs on bone and apatite surfaces in a closed-packed manner with the straight-chain molecules in parallel array with the end carboxyl groups hydrogen bonded to surface electronegative ions. Synthetic hydroxyapatite has long been used in chromatography because of the bonding capacity apatite surface has for certain proteins and polynucleotides. The metabolic interplay between bone mineral and the body results from the high magnitude and high reactivity of the mineral surface.
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    Journal of Biomedical Materials Research 19 (1985), S. 615-629 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A radiation polymerized drug-vinyl copolymer delivery composite (0.8 mm in diameter, 3 mm long) was inserted into the right-lobe ventral prostate (I), into the right testis (II), and subcutaneously (III) into the back of male Wistar rats. The implantation was carried out over a period of 12 weeks maximum. From the relationship between the site of surgical insertion of the implant and the physiologic response (as measured by the decrease in the weight of the prostatic organs, e.g., ventral prostates, dorsolateral prostates, and seminal vesicles), it was found that in an AA560-containing composite (36 μg daily), the physiologic response is increased in order of (III) 〉 (II) 〉 (I). The same tendency was observed in the Estracyt-containing composite system (15 μg daily). The difference in the physiologic response owing to the site of surgical insertion of the implant was not observed in an E2-17β-containing composite (6 μg daily), although this composite showed the strongest physiologic response. No physiologic response in rats with CMA-containing composite (28 μg daily) was noted.
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    Journal of Biomedical Materials Research 19 (1985), S. 991-1010 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Biomedical Materials Research 19 (1985), S. 1031-1041 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was conducted to examine if an aminoglycoside (dibekacin sulfate, DKB) incorporated into a coating layer on outer and inner surface of indwelling catheters would be released into urine both in vitro and in clinical cases on a sustained basis and if the released DKB would have any efficacy on delaying lower urinary tract infections. Released amounts of DKB from the catheter silicone rubber (SR) catheter were periodically measured both in vitro and in clinical applications. During the clinical applications, the catheters were indwelled in 14 patients. Organism counts in the patients' urine were determined and organisms were isolated from bacteriuria (defined as ≧104 CFU/mL) and MICs to DKB were measured. Observations on several combined symptoms frequently associated with indwelling catherization were performed. Results showed that sustained release of DKB continued for more than 25 days and 13 days in vitro and in clinical cases, respectively. Clinical studies suggested that 8 days of sterile urine after catherization might be expected in patients without systemic administration of antibiotics and more than 2 weeks if combined with it. No particular problems in its use and associated symptoms were recognized.
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    Journal of Biomedical Materials Research 19 (1985), S. 1073-1084 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The electrochemical behavior of aluminum in isotonic saline solutions, citrated human plasma, and citrated human blood is studied using potentiostatic and potentiodynamic polarization techniques complemented with scanning electron microscopy (SEM) and dispersive x-ray analysis. The effect of corrosion products on plasmatic proteins is investigated using electron microprobe analysis and immunoelectrophoresis analysis. Electrochemical data show a breakdown of the protective film on aluminium, due to the action of chloride, leading to the pitting of the metal. During pitting, the interaction of aluminium ion and the plasma proteins produces a nonadherent precipitate. Strong protein denaturation can be observed by immunoelectrophoresis of the precipitate suspended in physiologic solutions. The convenience of using organic fluids in addition to saline solutions to evaluate in vitro the behavior of metal for implants is suggested.
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    Journal of Biomedical Materials Research 19 (1985), S. 1101-1115 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Macrophage adhesion to a wide variety of substrates has been measured, but no systematic study of the influence of specific substrate chemical properties on adhesion is available. These studies were conducted using two series of materials, copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) and copolymers of hydroxystyrene and styrene, to determine the effect of a single chemical property, polar character, on adhesion. Rat periotoneal macrophages were allowed to contact polymer substrates for periods ranging from 1 to 240 min before being subjected to a shear stress of 60-120 dynes/cm2 in a thin-channel flow cell. Percentage adhesion was calculated from the number of cells that remained adherent to the substrate after 30 s of applied shear stress. Macrophages remained adherent to 100% EMA and all hydroxystyrene-styrene copolymer surfaces after only 1 min of contact. In copolymers of the HEMA-EMA series, the time required to attain peak adhesion levels increased with increasing substrate hydrophilicity (increasing HEMA content). Cells did not attach to the 20% EMA/80% HEMA copolymer and the 100% HEMA polymer. The results demonstrate that there is a time delay between contact and adhesion of the cells to surfaces of increasing hydrophilicity within the HEMA-EMA series and no time delay with the hydroxystyrene-styrene series. The time delay is thought to be a function of the excluded volume provided by polymers that are able to undergo significant chain rotation and or swelling in the solvent, water. Small excluded volumes present in copolymers of high EMA content and all hydroxystyrene-styrene copolymers offer little or no resistance to formation of adhesive bonds by macrophages, whereas copolymers with large excluded volumes (high HEMA content) prevent contact and/or adhesion. A mechanism based on the net excluded volumes of both the cell and substrate surface macromolecule is proposed to explain this phenomenon.
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    Journal of Biomedical Materials Research 20 (1986), S. 261-271 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of this investigation was to determine some mechanical properties of eight different posterior composites, and how they are affected by water sorption. Creep characteristics in compression were expressed as compliance/log time functions. Stress-strain relationship at a constant loading rate was determined both in compression and flexure, and presented as elastic modulus, ultimate strength, and ultimate strain. Water sorption increased creep values for all materials. Generally, the materials with the highest water sorption had the highest increase in creep. Water sorption decreased the elastic modulus and ultimate strength values. The creep values decreased and the elastic modulus increased with increasing quantity of inorganic fillers.
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    Journal of Biomedical Materials Research 20 (1986), S. 153-168 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The ability of a biomaterial to withstand the rigors of the harsh biologic environment is an important consideration when considering a material for long-term biomedical applications. Using a cage implant system, the effects of an intense inflammatory reaction on cast Biomer have been investigated. The inflammatory response to cast Biomer was greatly increased by coimplanting Biomer films with a cytotoxic poly(vinyl chloride) (PVC) in rats for a period of 21 days. Cast Biomer films were characterized by weight, advancing contact angle with water in air, attenuated total reflectance infrared spectroscopy and scanning electron microscopy (SEM). The analyses were performed before any treatment, after autoclaving and sonication, and after 21 days implantation with the cytotoxic (PVC) in rats. The results of the study indicated that cast Biomer does not undergo significant chemical degradation when subjected to the effects of an intense inflammatory reaction for 21 days. Implantation does, however, lead to rearrangement that results in a more polar and hydrophilic surface, suggesting that the polymer adapts to the hydrophilic environment of the inflammatory exudate.
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    Journal of Biomedical Materials Research 20 (1986), S. 205-212 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of alkyl 2-cyanoacryloyl glycolate tissue adhesives were synthesized and characterized by NMR. Physical properties and bond strengths are presented. Within the series, bond strength decreased with increasing molecular weight. Corresponding polymers were evaluated by in vitro and in vivo techniques for biocompatibility. In general, in vitro biocompatibility increased with molecular weight. Based on in vitro and in vivo results, the isobutyl and isoamyl derivatives gave polymers that were most biocompatible, however, the entire series was found to be less reactive than poly(methyl 2-cyanoacrylate) and only the isopropyl derivative polymers more reactive than poly(isobutyl 2-cyanoacrylate). Approximately one-third of the isobutyl polymer biodegraded in vivo after 6 weeks.
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    Journal of Biomedical Materials Research 20 (1986) 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 20 (1986), S. 411-412 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 20 (1986), S. 415-415 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 20 (1986), S. 433-468 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Despite the use of polyurethanes in a number of blood-contacting applications, little is known about the contributing effects of the various polyurethane components in thrombogenesis. In order to investigate blood-polyurethane interactions, a number of different polyurethanes were examined in an acute canine ex vivo series shunt experiment. Multiprobe surface characterization techniques, including contact angle measurements, ESCA, ATR-IR, and SEM were used to obtain surface property information on the materials studied. The polyurethanes examined included several with different soft segment types, a series of materials with different hard segment diisocyanates and chain extenders, a series consisting of the same polymer cast from different solvents, a zwitterionomer, and a hard segment analog. Two commercial urethanes were also examined, and the effect of methanol extraction on these materials was studied.The blood-contact and surface characterization results indicated that both the surface concentration and type of hard segment were of importance in determining blood response. The relative concentration of hard segment on the polymer surface was found to affect the observed blood-material interaction, although the extent of this effect was found to depend on the hard and soft segment components of the copolymer system. Both the surface properties and thrombogenicity of a particular polyurethane were changed by casting from different solvents, indicating the need to optimize and control fabrication conditions. Methanol extraction was found to improve the thromboresistance of the commercial polyurethanes.
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    Journal of Biomedical Materials Research 20 (1986), S. 555-563 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The changes in mechanical properties and free radical concentration of curing Simplex P Radiopaque Bone Cement in vivo and in vitro conditions were studied. Samples were prepared so that each in vivo sample that cured and aged in the canine femoral intramedullary cavities had an in vitro counterpart that was cured and aged in a constant-temperature saline bath at 37°C. An electron paramagnetic resonance (EPR) spectrometer was used to measure the growth and decay (curing) of polymerization radicals. The results of EPR measurements showed that the curing (disappearance of free radicals) of in vivo samples takes a much longer time (more than 4 weeks) than in vitro curing (less than 2 weeks). The mechanical tests indicate that, whether aged in vivo or in vitro, the strength increased rapidly for the first 1-2 weeks and then slight increases were seen for up to 6 months.
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    Journal of Biomedical Materials Research 20 (1986), S. 547-553 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study evaluated Fibrin Sealant (FS), a two-component biologic adhesive that is effective in establishing hemostasis, in 27 experimentally produced splenic injuries in five adult mongrel dogs. Ten small superficial lacerations (2.0 cm in length), six large superficial lacerations (3.0-6.0 cm in length), three small wedge resections, and eight stab wounds extending into the splenic hilum were effectively repaired with FS without suture splenorrhaphy or temporary splenic hilar occlusion. Complete hemostasis was achieved in all animals prior to skin closure. Dogs were reexplored postoperatively at intervals varying from 4 h to 6 weeks. When animals were killed, there was no gross evidence of splenic disruption or recurrent bleeding; the spleens all had developed well-healed capsules. Histologic examination demonstrated a regenerated fibrous capsule extending over the injuries without significant inflammatory response. We conclude that FS (1) provides adequate hemostatic control of superficial and deep splenic injuries; (2) has good systemic and local compatibility; (3) can be applied to bleeding parenchymal wounds; organ ischemia is generally not required; (4) avoids the use of parenchymal sutures, which may be traumatic; and (5) may promote splenic wound healing. Thus, use of FS is an effective technique for splenic preservation after trauma.
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    Journal of Biomedical Materials Research 20 (1986), S. 579-587 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Tracheal stenosis is a devastating complication of tracheal resection that may be related to improper suture selection and technique, as well as extensive surgical devascularization. This study evaluated Fibrin Sealant (FS) (Immuno AG, Vienna, Austria), a two-component biologic adhesive, as a method for reducing the need for sutures in tracheal surgery. This adhesive has been found to be effective in face-to-face sealing of tissues, wound healing, and in establishing hemostasis. Six adult mongrel dogs underwent tracheal repair with FS. Three had tracheal hemitransections (approximately three quarters of the circumference) and were repaired using one absorbable suture and FS, and three had complete transections (with resection of two tracheal rings each) repaired using five absorbable sutures and FS. The animals were killed at varying intervals ranging from 6 h to 6 weeks. No animal had gross evidence of significant tracheal stenosis, and the endotracheal mucosa appeared well healed. We conclude that the use of FS in tracheal reconstruction results in a stable, leakless trachea, and that it significantly reduces the number of sutures needed; this may lead to a decreased potential for anastomotic ischemia and tracheal stenosis.
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    Journal of Biomedical Materials Research 20 (1986), S. 667-676 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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    Journal of Biomedical Materials Research 20 (1986) 
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    Journal of Biomedical Materials Research 20 (1986), S. 723-730 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An investigation of red blood cell interactions with “foreign” surfaces is reported. Experiments consisted of flowing suspensions of washed human red cells through a packed column of either glass or siliconized glass beads. Conditions were chosen so that hemolysis was minimized. The column was washed to remove suspended red blood cells and then eluted. Samples of beads were examined by SEM after washing and before elution. The eluate was examined by UV/visible spectroscopy and SDS-PAGE; for both types of packing it was found to contain cell membrane components. It is therefore concluded that membrane material is deposited on the bead surface as the cells flow through the column. The SDS-PAGE data show that membrane skeleton proteins are essentially missing from the eluate, while SEM examination indicates the presence of filamentous deposits on the bead surfaces. These data suggest that cell-surface interaction may occur through a tether-type mechanism involving extrusion of part of the membrane including the integral membrane proteins.
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    Journal of Biomedical Materials Research 20 (1986), S. 773-784 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To determine whether the surface free energy of polymer materials influences the spreading and growth of cells, surface free energies of 13 polymers and glass were related to spreading and growth of human skin fibroblasts. Experiments were performed in both the presence and absence of serum proteins. We calculated the surface free energy from contact angles of phosphate-buffered saline (PBS), n-propanol/PBS mixtures, and α-bromonaphthalene on the polymers, using the concept of polar and dispersion components accounting for spreading pressures. Cell spreading and substratum surface free energy (γs) showed a characteristic sigmoid relationship both in the presence and in the absence of serum proteins; good spreading only occurred when γs was higher than approximately 57 erg · cm-2. In the presence of serum proteins, cell spreading is similar on most materials; only few materials show relatively high cell spreading. Cell growth in the presence of serum proteins did not differ significantly on the various polymers with reference to their γs values. In contrast, two groups of polymers could be distinguished in the absence of serum with respect to cell growth. The first group showed increasing γs, whereas the second group showed consistently low cell growth. The results demonstrate the complex relationship between cell spreading and substratum surface free energy as well as the role of serum proteins in modifying the surface characteristics of polymers in relation to cell spreading and growth.
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    Notes: Acrylic bone cement is significantly weaker and of lower modulus of elasticity than compact bone. It is also weaker in tension than in compression. This limits its use in orthopedics to areas where tensile stresses are minimum. Many authors have shown that addition of small percentages of fiber reinforcement by hand mixing improved the mechanical properties significantly but with variable results. In this investigation we have examined the mechanical properties of machine-mixed, commercially available carbon-fiber-reinforced bone cement. Appropriate samples of normal low-viscosity cement and carbon-fiber-reinforced cement were prepared and tested mechanically. Carbon fiber increased the tensile strength and modulus by 30% and 35.8% respectively. The compression strength and modulus, however, increased by only 10.7%. Similarly, bending and shear strengths improved by 29.5% and 18.5%, respectively. Diametral compression strength, which is an indirect measure of tensile strength, however, showed only 6.2% improvement. The maximum temperature rise during polymerization was also reduced significantly by the fiber reinforcement.
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    Journal of Biomedical Materials Research 20 (1986), S. 861-865 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 92
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 951-962 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Collagen was isolated from rat tail tendons and acetylated with 1-14C acetic anhydride. In situ adsorption of this collagen from a buffer solution (pH = 2.7) was measured at the interfaces to air, polyethylene and polyethylene grafted with poly(maleic acid), respectively.The kinetics of adsorption were recorded for all surfaces studied and the corresponding diffusion coefficients for collagen in solution with various protein concentrations were calculated. The desorption of collagen from polymer surfaces was also studied.These experiments reveal the existence of both a reversibly and an irreversibly adsorbed collagen layer on the polymers tested. The desorption/adsorption ratio for the polyethylene is higher than that for the grafted polyethylene indicating stronger interactions of collagen with the grafted surface than with the non-modified polyethylene.
    Additional Material: 7 Ill.
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  • 93
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Block copolymers were synthesized by a coupling reaction of hydrophilic chains of poly(2-hydroxyethyl methacrylate) (PHEMA) with hydrophobic chains of polystyrene (PSt), or poly(dimethyl siloxane) (PDMS). Microstructures of films of the block copolymers exhibited a hydrophilic-hydrophobic microphase separated structure. For evaluation of in vivo antithrombogenicity, small diameter tubes (1.5 mm I. D. and 20 cm length) coated by the copolymers on their internal surfaces were implanted in rabbits as arteriovenous shunts. Occlusion times of the tubes, measured by formation of thrombus, were three days for PHEMA, two days for PSt, and three days for PDMS. The block copolymers showed excellent antithrombogenic properties: occlusion times were 20 days for HEMA-St block copolymer and 12 days for HEMA-DMS block copolymers. In vitro examination of polymer-platelet interaction in terms of platelet adhesion and aggregation, which are important initial processes of blood coagulation, demonstrated suppressed adhesion and aggregation on microdomain surfaces constructed of hydrophilic and hydrophobic block copolymers. From both in vivo and in vitro examination, it was concluded that HEMA-St and HEMA-DMS block copolymers showed promising antithrombogenic activities by suppressing activation and aggregation of platelets.
    Additional Material: 5 Ill.
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  • 94
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Macroporous hydroxyapatite was implanted submucosally in the rat middle ear and studied after intratympanic injection of a Staphylococcus aureus suspension. The middle ear infection was induced 1 week after the implantation, and the effects of infection on the middle ear and the implant material were evaluated after 1, 3, 7, and 14 days by light and electron microscopy. The findings in the infected middle ear with an implant corresponded well with those described for the infected middle ear cavity without an implant. The reactions of the tissue over the implant were similar to those of the original mucosa of the middle ear.Bone was deposited on the implant and in its pores in relatively large quantities. Biodegradation, due at least partially to phagocytic activity of macrophages and multinucleated cells, was more prominent than previously found. This higher degree of biodegradation may be attributed to the use of the mucosal implantation technique, because this was the only point of divergence with respect to material or methods from earlier work reported by our group.The present results, together with those published earlier, suggest that this material has promising features for use as a bone substitute in reconstructive middle ear surgery. Definitive conclusions on biological performance and biofunctionality will, however, have to await long term clinical trials.
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  • 95
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Block copolymers constructed from chains of poly(2-hydroxyethyl methacrylate) (PHEMA) and either poly-ethyleneoxide (PEO) or poly-propyleneoxide (PPO) were synthesized. These block copolymers exhibited microdomain structure. Platelet adhesion on their surfaces was investigated by a column elution method to examine the effect of microdomain structure. The number of platelets adhered from whole blood was smaller for the block copolymer systems than for the homopolymers. Minimum points of platelet adhesion appeared at approximately 0.38 mol fraction of HEMA in the HEMA-PO system. Both block copolymer surfaces showed microdomains of alternate lamellar structure. Furthermore, the percent of platelets released from the column after incubation was investigated using PRP. In the case of homopolymers, released platelet percentages decreased with an increase of incubation time. Released platelet percentages from the block copolymers, however, were nearly constant with changing incubation time. These results showed that HEMA-EO and HEMA-PO block copolymers had the ability to suppress both reversible and irreversible adhesion of platelets to their respective microdomain surfaces.
    Additional Material: 10 Ill.
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  • 96
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 1111-1123 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Macrophages play a central role in the pathogenesis of inflammation. In addition, activated macrophages are the first cells to come in contact with foreign particles in tissue. In the present study the applicability of macrophages for In vitro biological screeining of dental materials was tested. Monolayers of murine peritoneal macrophages were prepared. After three days culture the macrophages were inoculated with alloy particles prepared from silver and tin (Ag3Sn), the γ-phase of dental silver-amalgam. After different inoculation periods the macrophages were fixed and examined with phase contrast microscopy, scanning electron microscopy, and energy dispersive x-ray analysis. Comparison with phagocytosis of particles injected intraperitoneally was also performed. Macrophage cultures inoculated with Latex particles served as controls. Ten minutes after inoculation with alloy particles, about 58% of the macrophages had ingested particles. EDAX-analysis indicated that the phagocytized alloy particles contained both silver and tin in the same proportions as in the original alloy. When the cultures had been inoculated for ten days, however, a marked reduction in phagocytosis was observed probably due to cytolysis of those macrophages which initially had phagocytized the alloy particles. The results indicate that, although the Ag3Sn alloy particles at all the time intervals studied were phagocytized more slowly and to a lesser extent than the Latex particles, the method could be of value in studying the biocompatibility of dental materials available in particulate form.
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  • 97
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 1179-1195 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyaminoetherurethaneureas bearing tertiary amino groups in the main chain (M-PAEUU) were synthesized, quaternized (Q-M-PAEUU) and heparinized (H-M-PAEUU). With increasing portions of diisocyanate and with decreasing portions of polyaminoether in the feed, M-PAEUU containing more hydrogen-bonded urea carbonyl groups was prepared. With increasing hydrogen-bonding character of M-PAEUU, the adsorbed bovine serum albumin (BSA) was more denatured. By quaternization of M-PAEUU, the protein adsorption increased, but the denaturation of adsorbed proteins was suppressed. With increasing ratio of hydrogen-bonded urea carbonyl groups in Q-M-PAEUU, the adsorptions of BSA, bovine serum γ-globulin (BγG), and bovine plasma fibrinogen (BPF) were decreased, but the degree of denaturation of adsorbed proteins was increased. In the adsorption to H-M-PAEUU, both the amount and the degree of denaturation of adsorbed proteins were strongly decreased. The dynamic adsorption experiments of plasma proteins showed the behaviors which are similar to the equilibrium adsorption experiments. The decrease of hydrogen-bonded urea linkages and the increase of hydrophilicity by quaternization and heparinization of the polymer surface may be favorable for building up a hydration layer on the surface, thus suppressing the denaturation of plasma proteins which may trigger blood clotting and thrombus formation.
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  • 98
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 1249-1256 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The metatarsal bone was elongated by intercalary implantation of a single-crystal alumina ceramic in 7 patients with brachymetatarsy. The implants were encased with new bone 24 months after surgery and resulted in 5.2 to 9.2 mm elongation of the metatarsal bone. The response of the bone to the ceramic implant was observed roentgenographically. No resorption or pseudoarthrosis of the bones, nor loosening or breakage of the implants, were observed. The alumina ceramic implant proved to be a useful substitute for a bone graft, because of its biocompatibility and strength.
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  • 99
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. ix 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 100
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 20 (1986), S. 1309-1333 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An endodontic implant model system was used to compare the effect of implant design on stabilization in bone. Specifically a porous-surfaced design was compared to conventional threaded and smoothtapered endodontic implant designs. All implants were placed in immediate function thereby assessing the effect of early limited movement on the fixation achieved. A total of eighty-three endodontic implants were inserted in the mandibles of six adult mongrel dogs. Animals were sacrificed immediately after implantation and after 3, 6, and 12 months. Implants were evaluated by clinical and radiographic examination and after animal sacrifice by pull-out tests of the implant from the tissues, SEM examination of the pulled-out implants and, finally, histology. The pull-out test results indicated increasing shear strength with implantation time for the porous-surfaced implants in contrast to the gradual loss of fixation for the threaded implants and the continuous low shear strength for the smooth implants. Histological studies and SEM examination indicated the reason for these changes. Smooth implants became encapsulated by fibrous connective tissue from early post-implantation time periods. Threaded implants, although initially mechanically interlocked with bone, developed a fibrous connective tissue capsule that gradually thickened with time until, by 6 months, little mechanical interlock of bone and implant was present. It was assumed that this fibrous capsule thickening was caused by implant movement. The porous-surfaced implants, however, became stabilized by bone ingrowth and showed more extensive bone formation within the surface pores with time. It is concluded that for implants that are made functional immediately after implantation, as in this study, porous-surfaced implants can become strongly fixed by bone ingrowth, in contrast to conventional threaded or smooth-surfaced designs, thus presenting a more favourable long term prognosis.
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