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  • Artikel  (719)
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  • 1985-1989  (719)
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  • Medizin  (719)
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  • 1985-1989  (719)
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  • 1
    Digitale Medien
    Digitale Medien
    The influence of different nutrients on plasma cholecystokinin levels in the rat (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 21-23 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Rats ; nutrients ; cholecystokinin ; pancreatic secretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Isocaloric and isovolemic amounts of protein (casein), fat (intralipid) and carbohydrate (saccharose) and an isovolemic control solution of water were administered intragastrically to conscious rats. The plasma CCK levels, determined by a sensitive and specific radioimmunoassay, showed an increment of 6.3±0.6, 2.7±0.5, 1.7±0.4 and −0.9±0.4 pM, respectively (basal value 2.5±0.3 pM). The threshold increment of plasma CCK to stimulate pancreatic enzyme secretion by exogenous CCK was found to be 1.5 pM. It is therefore concluded that casein is a potent stimulus for CCK secretion and pancreatic secretion, but that fat and even carbohydrate, although less potent, also produce a CCK increment above the threshold for pancreatic secretion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01960229
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  • 2
    Digitale Medien
    Digitale Medien
    Kinetics of cell adhesion to polymer surfaces (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 215-229 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Results of the kinetics of adhesion of granulocytes as well as fresh and glutaraldehyde-fixed erythrocytes, suspended in Hanks Balanced Salt Solution (HBSS; pH 7.2, ionic strength of 0.15) to various polymeric substrates are presented. Cell adhesion increases rapidly initially and reaches a plateau value after approximately 30 minutes. There is no evidence for a lag-time in the onset of cell adhesion, suggesting that electrostatic double-layer forces are negligible under these experimental conditions. For the experiments in which the cells are suspended in HBSS, which has a surface tension larger than that of the cells, the level of cell adhesion increases with decreasing surface tension of the polymeric substrates. An additional experiment with fresh human granulocytes suspended in HBSS containing 10% dimethyl sulfoxide was also performed. The surface tension of the resulting liquid medium is below that of the cells and the pattern of adhesion is reversed, in agreement with the predictions of a thermodynamic model for cell adhesion. The slightly different behavior of siliconized glass as a substrate is discussed in terms of „screening“.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220306
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  • 3
    Digitale Medien
    Digitale Medien
    The effect of post-sintering heat treatments on the fatigue properties of porous coated Ti-6Al-4V Alloy (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 287-302 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Porous coated Ti-6Al-4V alloy implant systems provide a biocompatible interface between implant and bone, resulting in firm fixation and potential long-term retention via bony ingrowth. In order to achieve an acceptable porous coating structure, the sintering protocol for Ti-6Al-4V alloy systems often requires that the material be heat treated above the beta transus. This transforms the as-received equiaxed microstructure, recommended for surgical implants, to a lamellar alpha-beta distribution, which has been shown to have the worst fatigue properties of the most common structures attainable in Ti-6Al-4V alloy. However, post-sintering heat treatments may be used to improve these properties by producing microstructures more resistant to crack initiation and propagation. This study investigated the influence of microstructural variations on the fatigue properties of porous coated Ti-6Al-4V alloy material. Nonporous coated and porous coated Ti-6Al-4V alloy fatigue specimens were subjected to a standard sintering heat treatment to produce a lamellar microstructure. In addition, two post-sintering heat treatments were used to produce coarse and fine acicular microstructures. Rotating beam (reversed bending) fatigue testing was performed and the endurance limits determined for the noncoated and porous coated microstructures. The values determined were 668 MPa (noncoated asreceived equiaxed), 394 MPa (noncoated lamellar), 488 MPa (non-coated coarse acicular), 494 MPa (noncoated fine acicular), 140 MPa (porous coated lamellar), 161 MPa (porous coated coarse acicular), and 162 MPa (porous coated fine acicular). The noncoated coarse and fine acicular specimens displayed an approximate 25% increase over the noncoated lamellar specimens. The porous coated coarse and fine acicular specimens showed an approximate 15% improvement over the porous coated lamellar specimens.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220404
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  • 4
    Digitale Medien
    Digitale Medien
    Cellular morphology and distribution on a stretching blood-material interface (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 339-351 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: In order to investigate the interactions of cellular elements and protein on constantly deforming (fatiguing) blood contact surfaces, a series of ex vivo canine arteriovenous shunt experiments were conducted. While fresh blood was flowing through Silastic tubing shunts, portions of the tubing were stretched 20 to 60% at a frequency of 20 to 90 cycles per minute for 10 to 90 min. The surfaces of the tubing that were stretched were compared with control tubing surfaces taken from the arterial side of the test segment using scanning electron microscopy and interference phase contrast microscopy.Approximately the same number of platelets were deposited on the stretched as on the unstretched portions of the tubing in the ten minute experiments. On the control portions of the tubing, the platelets were deposited singly and uniformly in what appeared to be a fairly inactivated state. On the stretched tubing, more pseudopod extension and aggregation was observed. In these preliminary experiments, no differences were noted as a function of frequency of stretch. As the blood contact time and the percent stretch were increased, only nonuniform, scattered aggregations of platelets, and platelets mingled with fibrin were seen. Significant numbers of spread white blood cells were observed on many of the segments of Silastic tubing stretched 20% for as short a time as 15 min. Granulocytes have occasionally been reported on less hemocompatible biomaterials after exposure to canine blood. This helps to confirm that substrate stretching of 20-60% had an adverse effect on the blood compatibility of the Siliastic tubing.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220407
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  • 5
    Digitale Medien
    Digitale Medien
    Cell adhesion to a series of hydrophili-hydrophobic copolymers studies with a spinning disc apparatus (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 383-404 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Adhesion of cells to substrates strongly influences many of their functions and therefore plays an important role in a variety of processes, including phagocytosis, hemostasis, and the response of tissue to implanted materials. In previous studies, the influence of substrate hydrophilicity on cell adhesion has not been separated from effects due to major differences in other properties of the substrate, such as charge, rigidity, and the specific chemical composition of the materials. In addition, very few careful studies of the force required for cell detachment from various substrates have been performed. In this study, 3T3 cell detachment from a chemically homologous series of copolymers based on hydroxyethylmethacrylate (HEMA) and ethylmethacrylate (EMA) was measured with a spinning-disc apparatus. The spinning-disc technique allowed measurements of cell detachment over a wide range of applied shear stress on each sample. Cell detachment did not occur until a critical value of shear stress was exceeded. The critical shear stress of detachment decreased linearly with increasing HEMA content, from 18 dynes/cm2 on poly-EMA to 0 on the polymers containing 83% or more HEMA. “Plating efficiency,” calculated as the fraction of cells initially applied which remained after dip rinsing the surfaces, did not vary significantly among most of the copolymers. Dip rinsing, however, exposes the cells to only one, relatively low shear stress (estimated to be somewhat less than 3 dynes/cm2). The existence of a critical shear stress for 3T3 cell detachment suggests that cell adhesion to surfaces cannot be fully understood with single shear stress methods because cells may attach with a wide range of strengths which are either all above or all below the applied shear stress. The influence of surface hydrophilicity on cell adhesion and the variety of forces which may contribute to this phenomenon are discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220503
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  • 6
    Digitale Medien
    Digitale Medien
    Albumin adsorption on alkyl chain derivatized polyurethanes: I. The effect of C-18 alkylation (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 359-382 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The initial adsorption rate of delipidized Human Serum Albumin (HSA) is increased by addition of C-18 alkyl chains to a poly-urethane. The presence of alkyl chains does not appear to influence the total amount of HSA adsorbed after one hour exposure to a 5.0 mg/mL HSA solution. Neither does the desorption following one hour of adsorption appear to be influenced by the presence of alkyl chains. A study of the effects of solution concentration and temperature showed that the initial adsorption rates on both polymers are proportional to the protein concentration raised to the 0.36 power, and that alkylation of the polymer increases the activation energy of the initial adsorption rate above the 14 kJ/mol observed for the underivatized polyurethane. A new technique is presented to quantify the mass of adsorbed protein using Fourier transform infrared spectroscopy and attenuated total reflection optics. This technique uses the absorbance of bulk protein as an internal calibration reference, and appears to be as accurate and perhaps more precise than radiolabeling techniques.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220502
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  • 7
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 441-442 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220507
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  • 8
    Digitale Medien
    Digitale Medien
    Effects of a grooved epoxy substratum on epithelial cell behavior in vitro and in vivo (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 459-473 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The effects of grooved epoxy substrata on epithelial (E) cell behavior were studied in vitro and in vivo. V-shaped grooves, 10 μm deep, were produced in silicon wafers by micromachining, a process which was developed for the fabrication of microelectronic components. The grooved substrata were replicated in epoxy resin. More E cells attached to grooved surfaces than to adjacent smooth surfaces. Clusters of E cells were markedly oriented by the grooved surfaces in comparison to the adjacent smooth surfaces where the orientation was random. Grooved and smooth epoxy implants were placed percutaneously in the parietal area of rats. One week after implantation E cells were found to adhere tightly to the implant surfaces. In the grooved portion of the implant E cells interdigitated into the grooves and had rounded nuclei. Histomorphometric measurements indicated that there was a shorter length of epithelial attachment and a longer length of connective tissue attachment in the grooved, compared to the smooth, portion of implants. After 10 days the epithelial attachment had migrated down the length of the protruding smooth portion of the implant and was located on the base of the implant. However, epithelium remained attached to the grooved portion of the implant. These observations indicate that grooved surfaces have the potential to impede epithelial downgrowth on percutaneous devices.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220603
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  • 9
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 589-591 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220612
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  • 10
    Digitale Medien
    Digitale Medien
    Serotonin and β-thromboglobulin release reaction from platelet as triggered by interaction with polypeptide derivatives (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 595-611 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The effect of wettability of 14 polypeptide derivatives upon adhesion and activation of platelets was investigated with reference to release reactions from adhered platelets, using radioisotope labeling and radio-immunoassay method. The serotonin release was more significant from platelets adhered to polymer materials to which a large number of platelets are adhered. However, no clear relationship was found between adhesion of platelets and β-thromboglobulin release from adhered platelets. Therefore, stimuli inducing serotonin release and β-thromboglobulin release were considered to be from different origins. The trend in β-thromboglobulin release was well correlated with the extent of morphological change of adhered platelets as observed by scanning electron microscope. It was suggested that the determination of released β-thromboglobulin in association with the measurement of platelet adhesion could be useful for evaluation of blood compatibility of materials.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220702
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  • 11
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 667-669 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220707
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  • 12
    Digitale Medien
    Digitale Medien
    The hydrolytic stability of mitrathane (a polyurethane urea) - an x-ray photoelectron spectroscopy study (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 687-698 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The hydrolytic stability of microporous Mitrathane polyetherurethane urea vascular prostheses has been evaluated at pH 7 and pH 9, at 37°, 60°, and 80°C for time periods of up to 968 days. Mechanical strength was evaluated using a hydrodynamic burst test and surface chemical changes by x-ray photoelectron spectroscopy. The samples held at 80°C showed the greatest mechanical strength loss which corresponded to the hydrolysis of the urethane groups. It was concluded that the gross in vivo surface degradation of Mitrathane prostheses, observed after six months, could not have been caused by simple chemical hydrolysis alone, as the polymer was found to be stable at 37°C for at least 11 months.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220803
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  • 13
    Digitale Medien
    Digitale Medien
    The study of thermal and gross morphologic properties of polyglycolic acid upon annealing and degradation treatments (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 699-712 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The objective of this study is to alter the fiber morphology of a linear aliphatic polyester, polyglycolic acid, by annealing treatment and to examine the changes of its degradation properties. The annealing was done at 150°C, 170°C, and 190°C, and the specimens were annealed in four different strained conditions, freely hung, 0, 1, and 10%. After annealing treatments, the specimens were subject to in vitro hydrolytic degradation by immersing them in phosphate-buffer solution of pH 7.4 at 37°C for up to 28 days. The thermal properties and gross morphology of the specimens were obtained. It was found that annealing treatments resulted in initial higher levels of crystallinity, which, in turn, influenced the hydrolytic degradation of the fiber. Among all the annealing conditions, the freely hung specimens annealed at 190°C exhibited the most pronounced annealing effect on hydrolytic degradation, and was consistent with the observed gross morphologic changes. The change in the characteristics of fiber structure (i.e., the return to the stage of less oriented conformation upon freely hung annealing) was thought to be the cause.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220804
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  • 14
    Digitale Medien
    Digitale Medien
    Effect of particle size on the in vitro and in vivo degradation rates of poly(DL-lactide-co-glycolide) microcapsules (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 733-746 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Three different sieve size fractions of ergotcontaining biodegradable microcapsules were examined both in vitro and in vivo. The sieve sizes and average particle diameter, (μm), were: less than 45-75 (X̄ = 30); 75-106 (X̄ = 79), 106-177 (X̄ = 130). These microcapsules contained ca. 9% drug and were produced from 50:50 poly(DL-lactide-co-glycolide). The objective was to determine the effect of particle size on in vivo and in vitro degradation rates. The microcapsules were injected into rat gastrocnemius muscle and excised and examined at various time points up to 70 days. Initially a minimal tissue response was noted which was characterized by a sharply localized acute inflammatory reaction. Following this, connective tissue and foreign body giant cells engulfed the microcapsules at 20-30 days. Only vestiges of the microcapsules were found surrounded by minimal connective tissue and foreign body giant cells after 60-70 days. The tissue reaction was a minimal, sharply localized foreign body giant cell and connective tissue process for all three size groups of microcapsules. The largest microcapsules (X̄ = 130 μm) exhibited a slightly greater tendency to undergo in vivo and in vitro degradation relative to the other groups. However, it can be concluded that over the microcapsule size ranges examined minimal differences in the degradation properties of the polymeric matrices and consequently those of the microcapsules were noted.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220806
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  • 15
    Digitale Medien
    Digitale Medien
    Blood compatibility of surfaces modified by plasma polymerization (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 795-818 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Tubular blood-contacting polymeric materials were modified by plasma polymerization and evaluated in the baboon with respect to their capacity to induce both acute and chronic arterial thrombosis. Polymer surface composition was determined by electron spectroscopy for chemical analysis. Steady-state arterial thromboembolism was initiated by introducing tubular segments into chronic arteriovenous shunts. Rates of platelet destruction induced by the test materials were calculated from 111In-platelet survival measurements. Nine plasma polymers based on tetrafluoroethylene, hexafluoroethane, hexafluoroethane/H2, and methane, when deposited on silicone rubber, consumed platelets at rates ranging from 1.1-5.6 × 108 platelets/cm2-day. Since these values were near the lower detection limit for this test system, the plasma polymers were considered relatively nonthrombogenic. Acute thrombus formation was initiated by inserting expanded Teflon (Gore-Tex PTFE) vascular grafts into the shunt system. 111In-platelet deposition was measured by scintillation camera imaging over a 1-h exposure period. Standard PTFE grafts (10 cm × 4 mm i. d.) accumulated approximately 1 × 1010 platelets over this interval. While modification of PTFE grafts with a plasma polymer based on hexafluoroethane/H2 did not alter graft surface morphology, platelet deposition was reduced by 87% as compared to the controls (p 〈 0.001). We conclude that both the surface chemistry and texture of prosthetic materials influence thrombogenesis. The method of plasma polymerization may be useful for assessing the importance of these variables independently and, perhaps, for minimizing certain adverse blood-material interactions.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220904
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  • 16
    Digitale Medien
    Digitale Medien
    Attachment and spreading of human gingival fibroblasts on potentially bioactive glasses in vitro (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1043-1059 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The attachment and spreading of cultured fibroblasts on potentially bioactive glasses (bioglasses) of ten different compositions were studied. Human gingival fibroblasts were allowed to attach and spread on bioglasses for 1-72 h. Unreactive silica glass and cell culture polystyrene served as controls. The attachment and spreading of cells were examined by 3H-thymidine labeling of cells, planimetric analysis, cytological staining, immunocytochemistry, and scanning electron microscopy. The cell attachment to bioglasses and silica glass and the cell spreading on bioglasses were slower and cell morphology more elongated compared to control plastic. In spite of great differences in bioglass compositions no great differences in cell behavior on these surfaces were detected. Thus the initial events in the tissue-implant interface might be independent on the bioglass composition, and furthermore the differences in the organization of the tissue-implant interface in vivo might depend on the nature of the surrounding tissues and subsequent changes of the implant surface and the extracellular environement.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221108
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  • 17
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221201
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  • 18
    Digitale Medien
    Digitale Medien
    Samuel F. Hulbert (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1091-1092 
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    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221203
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  • 19
    Digitale Medien
    Digitale Medien
    The effect of plasma-sprayed calcium phosphate ceramic coatings on the metal ion release from porous titanium and cobalt-chromium alloys (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1137-1163 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Bone tissue ingrowth in porous materials is enhanced by the deposition of bioactive calcium phosphate ceramic linings onto the pore walls. These bioactive coatings can be deposited using several methods which yield a variety of coating efficiencies and thereby influence the mechanisms and kinetics of ion release from the metal. We analyzed the effect of plasmaspraying hydroxyapatite onto titanium and cobalt-chromium alloys by measuring the release of Ti, Al, V, Co, and Cr in vitro. Plasma-sprayed coatings significantly reduced the Ti and Al release from titanium-based alloy specimens. The tendencies of release from the cobalt-based specimens are less pronounced. The data substantiate that neither localized enhanced passive dissolution of metal ions nor ceramic shielding of the metal occurs. The Scanning Auger Electron Microprobe Spectroscopic data suggest that the dissipation of thermal and kinetic energy of the ceramic particle at the time of impact can produce compositional and structural changes in the metal surfaces. The resulting effects are significant for the titanium alloy but less significant for the Co-Cr alloy system.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221207
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  • 20
    Digitale Medien
    Digitale Medien
    Ceramic systems for long-term delivery of chemicals and biologicals (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1245-1266 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Evaluation of devices, drugs, and drug delivery systems have been investigated by both in vitro and in vivo procedures. Ceramic drug delivery systems can be used to evaluate chemicals and biologicals by both in vitro and in vivo procedures. The system can also reduce handling of the animals and facilitate long-term evaluations before conducting clinical trials. To date, ceramic systems have been used to deliver aldosterone, androstanedione, beta-lactoglobulin, bovine serum albumin, chymotrypsin, danazol, difluoromeythylornithine, dihydrotestosterone, estradiol, gamma globulin, gonadotrophic releasing hormone, gossypol, growth hormone, insulin, methylene blue, pepsin, progesterone, and testosterone. The data obtained suggest that ceramic delivery systems can be used in the near future to treat diseases requiring long-term chronic drug therapy as well as disorders caused by deficiency of certain hormones.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221212
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  • 21
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221301
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  • 22
    Digitale Medien
    Digitale Medien
    A tribute to Sam (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1089-1090 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221202
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  • 23
    Digitale Medien
    Digitale Medien
    Analysis of the biocompatibility of ALCAP ceramics in rat femurs (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1101-1126 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Ceramics composed of aluminum, calcium, and phosphorus oxides (ALCAP) were tested for compatibility as bone replacement biomaterials. Implantation of ALCAP ceramics in rat femurs had no deleterious effect on body weights, organ/body weight ratios, muscle, bone, blood, and kidney function. Aluminum resorbed from ALCAP ceramic bone implants was excreted in the urine and was not deposited in adjacent muscle. Plasma levels of aluminum were not elevated in rats implanted with ALCAP ceramics. Alkaline phosphatase activity of excised implant sites indicated greater bone formation in ALCAP ceramic implants than in bone autografts. Radiographs and implant histology demonstrated excellent bone association with implants and ingrowth of new bone into ALCAP ceramic implants. ALCAP ceramics are biocompatible and suitable for reconstruction of bone.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221205
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  • 24
    Digitale Medien
    Digitale Medien
    Multilayered bead ceramic composite coating for hip prostheses: Experimental studies and preliminary clinical resultsThis research was supported by the Ministero della Sanitá (Progetto Finalizzato “Definizione di modelli di studio di biocompatibilitá e di nuove protesi”) Italy. (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1181-1202 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The clinical use of a new ceramic composite material made up of multilayered alumina beads and adhered to a ceramic surface with a high-temperature-melting bioglass is proposed. The result is a structure characterised by a 27% porosity and an average pore diameter of 400 μm. The actual structure of the parts as well as their interface interaction were determined by Raman laser. The mechanical resistance of the adherence of this coating for the ceramic substratum was good enough to resist the stress to which it was submitted when used for a new model of prosthetic acetabulum. Experiments with rabbits revealed the good biocomatibility of the composite. The osteoproductive activity of the tissue surrounding the implant led to the gradual filling of the porosity with trabecular structures. The preliminary results of the clinical experience which began in November 1985, confirm the good compatibility of the ceramic composite.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221209
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  • 25
    Digitale Medien
    Digitale Medien
    Announcement (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1293-1293 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221214
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  • 26
    Digitale Medien
    Digitale Medien
    The editor's corner (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 113-117 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221303
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  • 27
    Digitale Medien
    Digitale Medien
    Biomaterial and implant surfaces: On the role of cleanliness, contamination, and preparation procedures (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 145-158 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Material specificity in implant-tissue interactions derives primarily from the surface properties (chemical composition, microstructure, etc.) of the implant. This article addresses several questions related to implant and biomaterial surfaces: What is the status of real implant surfaces (composition, cleanliness, contamination, microstructure, etc.), and how does it vary with preparation procedures? Can the surface status be varied and analyzed in a controlled manner? How significant are surface status variations for in vivo function? And so on. We discuss clean surfaces, how they are contaminated, and how the contamination may affect the properties. We also discuss different preparation procedures, such as conventional machining, plasma treatment, and sterilization. Three important conclusions are drawn: (i) The surface status of a particular implant material may vary widely depending on its preparation and handling history. (ii) The surface status of implants is expected to be important for in vivo function, and should thus be controlled and standardized. (iii) It is usually not possible to predict how a change in surface status will affect the longterm, in vivo function of an implant.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221307
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  • 28
    Digitale Medien
    Digitale Medien
    Wound healing using a collagen matrix: Effect of DC electrical stimulation (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 191-206 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Rapid fibroblast ingrowth and collagen deposition occurs in a reconstituted type I collagen matrix that is implanted on fullthickness excised animal dermal wounds. The purpose of this study is to evaluate the effects of direct current stimulation on dermal fibroblast ingrowth using carbon fiber electrodes incorporated into a collagen sponge matrix. Preliminary results suggest that fibroblast ingrowth and collagen fiber alignment are increased in collagen sponges stimulated with direct currents between 20 and 100 μA. Maximum fibroblast ingrowth into the collagen sponge is observed near the cathode at a current of 100 μA. These results suggest that electrical stimulation combined with a collagen matrix may be a method to enhance the healing of chronic dermal wounds.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221310
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  • 29
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221401
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  • 30
    Digitale Medien
    Digitale Medien
    Binding of heparin onto ethylene-vinyl alcohol copolymer membrane (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 269-280 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Heparin was ionically bound onto the surface of an ethylene-vinyl alcohol copolymer (EVAL) membrane which was derivatized by aminoacetalization to produce cationic surface charges. The amount of bound heparin was proportional to the ion exchange capacity of the aminoacetalized membrane and the maximal amount obtained in this experiment was 96 Unit/cm2 (0.59 mg/cm2). Plasma recalcification times were measured for the heparinized membrane thus obtained. Recalcification times increased proportionally with the amount of heparin bound on the membrane, while original EVAL membranes and the nonheparinized aminoacetalized membrane did not show increases in recalcification times. This means that the heparinized EVAL membrane has a more nonthrombogenic property due to the release of heparin. The apparent amount of heparin released from the membrane into plasma was estimated from plasma recalcification times. The release rate was 0.30-0.33 Unit/cm2/h (1.8 × 10-3 -2.0 × 10-3 mg/cm2/h) for the membranes whose surface was considered to be saturated with heparin. The release amount was about 0.6% compared to the adsorbed heparin in the case of the 96 Unit/cm2-heparinized membrane incubated in plasma for 60 min.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221407
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  • 31
    Digitale Medien
    Digitale Medien
    Heat transfer analysis of frictional heat dissipation during articulation of femoral implants (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 281-309 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Previous studies have shown the tendency for frictional heating to occur during articulation of total hip systems in vitro under simulated hip loading conditions. The magnitude of this heating is sufficient to accelerate wear, creep, and oxidation degradation of the UHMWPE bearing surface. It was shown that ceramic articulating systems generate less frictional heating than polished cobalt alloy against UHMWPE. This fricitonal heating is expected to occur primarily for younger, heavier, and more active patients. Thus, long-term performance of the articulating hip system in these patients may not be that predicted from current, body-temperature wear, creep, and degradation studies. Although the tendency to generate frictional heat has been observed only during in vitro simulated hip loading, a heat transfer analysis of this phenomenon is presented to evaluate the ability of the hip joint to dissipate such heating in vivo. Additional experiments were performed using controlled resistance heaters inside a cobalt femoral head to verify the calculated levels of frictional heat and to assess the heat dissipation under simulated in vivo conditions. The effect of blood perfusion on the effective thermal conductivity of the joint capsule is also discussed. The present study describes and analyzes the various heat dissipation mechanisms present both in vitro and in vivo during articulation of metal and ceramic hip systems. From these tests and analyses, it is concluded that frictional heating in the reconstructed hip cannot be effectively removed, and that degredative elevated temperature processes can be expected to occur in vivo to both the UHMWPE and adjacent tissue under extended periods of excessive patient activity. This is particularly true for metal cobalt alloy femoral heads articulating on UHMWPE versus ceramic heads which generate significantly lower levels of heat.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221408
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  • 32
    Digitale Medien
    Digitale Medien
    Calcium phosphate-coated porous titanium implants for enhanced skeletal fixation (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 191-201 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Porous titanium fiber implants for cementless skeletal fixation by bone ingrowth were treated with a calcium phosphate coating applied by a plasma flame-spray technique. In a paired experiment, treated and control implants were inserted in the humeri and olecranons of 36 adult dogs for periods of 1, 2, 4, and 6 weeks. After the animals were sacrificed, a biomechanical evaluation of the strength of skeletal fixation of the implants and a histologic evaluation of bone ingrowth was done. The mean shear strength of skeletal fixation at four weeks for the calcium phosphate-coated implants was 24% greater (p 〈 .01) than for paired controls. No difference in strength of fixation between treated and control implants was present at other time periods. The osteoconductive properties of the ceramic coating were demonstrated by bone forming in direct contact with the calcium phosphate coating on the metal fibers of the treated implants. No significant increase for the volume of bone ingrowth was established for treated implants compared to paired controls at any time period.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220304
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  • 33
    Digitale Medien
    Digitale Medien
    Interaction between erythrocytes and a perfluorochemical blood substitute (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 45-61 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Perfluorochemicals (PFCs) are being widely developed for use as erythrocyte substitutes to carry oxygen to tissue in acute crises. Oxypherol, a commercially available PFC preparation commonly used for animal tests, reduces erythrocyte deformability in the presence of plasma. This undesirable effect further complicates oxygen delivery by erythrocytes. Our experiments indicate that one or more plasma proteins must be present to observe Oxypherol-induced reduction in erythrocyte deformability, but the latter is not protein specific. Neither platelet activation nor enhanced protein adsorption could account for the mechanism of altered erythrocyte flexibility. Using fluorine-19 NMR, it was found that a small amount of Oxypherol droplets is adsorbed on the surface of the erythrocytes. The amount of adsorbed droplets increases when Oxypherol is incubated with the erythrocytes in the presence of plasma, in parallel with a decrease in erythrocyte deformability. Therefore, it seems likely that the loss of deformability of the erythrocytes is caused by the adsorption of small Oxypherol droplets on the erythrocytes.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220106
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  • 34
    Digitale Medien
    Digitale Medien
    A comparative scanning electron microscopic study on degradation of absorbable ligating clips in vivo and in vitro (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 71-79 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Using scanning electron microscopy, the degradation characteristics of two absorbable ligating clips, Absolok (polydioxanone) and Lactomer (poly-L-lactide-co-30%-glycolide) have been studied under in vivo and in vitro conditions. The rate of Absolok clip degradation was significantly greater than that of Lactomer clip degradation both in vitro and in vivo. The rate of degradation of Lactomer clips significantly increased and they showed a greater change in proportion of breakdown in vivo than in vitro compared to Absolok clips. The Absolok clip breakdown began with the formation of surface undulations which later developed into fissures. The undulations appeared on the clip surface as early as 7 days and by 2 weeks developed into fissures. The initial appearance of the fissures was at the edge of the clips particularly at the mating surface. The thickness of layers forming the fissures gradually decreased and by 15 weeks the layers appeared as very thin sheets of materials. The high energy areas (locking and molding points) were more resistant to breakown and the remains of the clips were still present 25 weeks after initiation of the experiments. The Lactomer clips showed very little sign of degradation in vitro even after 10 weeks of incubation. However, in the in vivo experiments undulations formed on the clip surface as early as 2 weeks postimplantation. These clips also showed fissures similar to those observed on Absolok clips.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220108
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  • 35
    Digitale Medien
    Digitale Medien
    Normal wound healing compared to healing within porous Dacron implants (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 121-135 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: This study examined the hypothesis that healing within porous implants differs from that in normal connective tissue. Special attention was given to extracellular components including collagen, reticular fibers, and ground substance, and to enzymes associated with activated macrophages. Using Dacron velour and the rabbit as host, the healing of normal connective tissue and that of the tissue/implant interface were histologically compared 10 and 28 days postimplantation. The results exhibited significant differences between connective tissue healing, implant capsule formation, and granulation tissue generation. The healing of connective tissue and implant capsule formation were essentially complete at 28 days. However, tissue inside the implant was qualitatively different and did not significantly change between 10 and 28 days. It was characterized by macrophages and giant cells, a predominantly acid mucopolysaccharide ground substance, and qualitatively fewer and less well defined collagen and reticular fibers were observed than in normal wound healing. Thus we conclude that the connective tissue inside Dacron velour does not resemble normal connective tissue after 10 or 28 days of healing. Furthermore, the collagen never fully matures into orderly bundles, a phenomenon which may be related to an altered mucopolysaccharide composition and a diminished reticular network. The lysosomal enzymatic activity of the macrophages and perhaps the giant cells at the tissue/implant interface may be linked to these differences.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220205
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  • 36
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220301
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  • 37
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220401
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  • 38
    Digitale Medien
    Digitale Medien
    Endothelialization of polymer surfaces (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 271-285 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The role that substrate surface properties play in influencing the extent of endothelialization of polymer surfaces has been investigated. For a wide range of polymer surfaces, the degree of endothelialization cells is directly related to polymer surface tension: increased endothelialization occurring with increasing substrate surface tension. As a result of adsorption of the proteins in the culture media, the surface properties of the polymers are altered considerably. The protein-coated polymers were characterized by means of liquid-liquid contact angle measurements under non-denaturing conditions. A striking correlation is observed between the degree of endothelialization and the measured dextran contact angle. The degree of endothelial cell spreading is not related to polymer surface tension. Cell morphology and extracellular matrix production, however, are influenced by substrate surface properties.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220403
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  • 39
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 353-355 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220408
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  • 40
    Digitale Medien
    Digitale Medien
    Preparation and properties of a biomaterial: HEMA grafted SBS by γ-ray irradiation (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 405-415 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Solvent-cast films of styrene-butadienestyrene triblock copolymer (SBS) were synthesized and a poly(2-hydroxyethylmethacrylate) (PHEMA) layer was grafted onto these films using Co 60 γ-ray irradiation. The IR absorption spectrum of the graft copolymer was taken and its surface morphology studied by a scanning electron microscope. The degree of grafting and the mechanical properties of SBS, SBS-g-HEMA, and PHEMA were measured. In order to study its biocompatibility, contact angle and blood clotting time experiments were performed. The degree of grafting was related to the soaking time, film thickness and total irradiation dosage. However, it levelled off at 7% when the total dosage reacehed 1 Mrad. It was found that the mechanical properties of SBS-G-HEMA were the same as those of SBS and were superior to those of PHEMA. The blood compatibility of SBS-g-HEMA as measured by the Lee-White clotting test was better than that of SBS and polystyrene and was quite similar to that of PHEMA.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220504
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  • 41
    Digitale Medien
    Digitale Medien
    Immobilization of enzymes on polypropylene bead surfaces by anhydrous ammonia gaseous plasma technique (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 417-422 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Anhydrous ammonia gaseous plasma technique was used for the surface modification of polypropylene beads. Amino groups were added onto the surfaces of beads by exposing them to ammonia plasma. Through these amino groups covalent immobilization of glucose oxidase and peroxidase were carried out. The total amounts of immobilized glucose oxidase and immobilized peroxdase were found to be 52 and 43 μg/cm2, respectively. To assess the stability of enzyme-polypropylene linkage, beads with covalently immobilized glucose oxidase and peroxidase were washed with phosphate buffer. It was found that after the removal of the adsorbed enzymes, the concentration of covalently immobilized enzymes tended to reach a steady state. After additional washing with buffer for 5 to 6 h, 40-55% of the immobilized enzymes were found to be in the active form.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220505
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  • 42
    Digitale Medien
    Digitale Medien
    Biocompatibility of six elastomers in vitro (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 423-439 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The biocompatibility of two silicone rubbers, Silastic and Dow Corning Elastomer, and of a polyether and a polyester urethane, a polyether polyester copolymer, and polypropylene oxide was assessed in vitro. These elastomers were selected for assessment as a possible alloplastic tympanic membrane. For these studies use was made of rat middle ear mucosa explants and serially cultured epithelium. The quantitative results were based on epithelial growth curves, the morphological picture was based on the findings in epithelium, and the aging of a biomaterial was simulated. Epithelium morphology was investigated by scanning and transmission electron microscopy and x-ray microanalysis. Quantitative results showed that on Dow Corning Elastomer and polypropylene oxide, cell proliferation was significantly lower compared to normal growth curves. The morphological findings were negative for polypropylene oxide, and did not discriminate between the other biomaterials under study. The simulation results indicated better biocompatibility for the polyurethanes and the polyether polyester copolymer compared with that of polypropylene oxide and both silicone rubbers. Under the simulation conditions, cells exposed to Silastic showed siliconcontaining inclusions. These in vitro results suggest that the biocompatibility of the polyurethanes and the polyether polyester copolymer is better than that of both silicone rubbers and polypropylene oxide.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220506
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  • 43
    Digitale Medien
    Digitale Medien
    Silicone rubber temporomandibular joint (TMJ) meniscal replacements: Postimplant histopathologic and material evaluation (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 475-484 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Medical grade silicone rubber has long been considered a suitable meniscal replacement, but there has been increasing concern about migration of this material into adjacent tissues. The objectives of this study were to determine the definitive composition of tissue-incorporated material which is presumed by light microscopy to be silicone and to identify long term histopathologic sequelae of meniscal replacements. Adult female patients underwent meniscectomy and replacement with silicone rubber (Silastic) implants. After 12 to 18 months, recurrence of symptoms in 8% of these cases led to implant removal with excision of peri-implant fibrous pseudo-capsules. Excised tissues, including one preauricular lymph node and implants were submitted for light microscopy, SEM, and energy dispersive x-ray microanalysis (EDX) for the identification of elemental composition, critical surface tension measurement, and internal reflection infrared spectroscopy. EDX revealed prominent peaks for silicon in both pseudocapsular and nodal tissues. Morphologic findings surrounding the long-term implants included foreign body reaction, synovitis, dystrophic calcification, fibrocartilaginous metaplasia, hyalinization, and scarring. Particulate silicone debris induced a pathologic response in the tissues and migrated to nodes. These findings suggest that periodic evaluation be performed over the life of such implants to rule out breakdown under function. These findings should intensify the search for improvements or replacements for silicone rubber as an interpositional material in the temporomandibular joint.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220604
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  • 44
    Digitale Medien
    Digitale Medien
    Crystallographic structure and surface morphology of sintered carbonated apatites (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 541-553 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Densely sintered synthetic hydroxyapatite (HA) is used as an implant material because of its excellent tissue biocompatibility. In order to maximize the biological potential of this calcium phosphate, we have investigated the incorporation of carbonate into HA to make a material which more closely resembles the mineral found in bones and teeth. The aim of the present study was to determine the conditions under which sintered carbonated apatites of specific carbonate content could be produced. The apatites were prepared by heating compressed pellets of precipitated carbonated apatite under a carbon dioxide/steam or nitrogen/steam atmosphere between 825 and 1050°C. The products were analyzed chemically and the surfaces examined by x-ray diffraction, infrared spectroscopy, reflected light microscopy, and scanning electron microscopy. The results showed that carbonate loss during sintering could be reliably predicted, making it possible to produce materials with specific carbonate content, and with specific physical and chemical composition.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220609
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  • 45
    Digitale Medien
    Digitale Medien
    Separation of B- and T-lymphocytes by cellular adsorption chromatography using poly(2-hydroxyethyl methacrylate)/polyamine graft copolymer as column adsorbent (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 555-571 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: A series of poly(2-hydroxyethyl methacrylate)/polyamine graft copolymers (HA copolymers) were examined as an adsorbent for cellular adsorption chromatography in order to separate cell populations with high efficacy. The capability of each copolymer sample to selectively adsorb rat lymphocyte subpopulations (B-cells and T-cells) was evaluated by applying a lymphocyte suspension to a copolymer-coated glass bead column. A separation factor (AB/AT) greater than 5.0 was achieved for the HA copolymer, compared to 1.9 and 1.1 for homopolymers of poly(2-hydroxyethyl methacrylate) and of a polyamine (poly(N,N-diethylaminoethylstyrene)), respectively. By loading a rat lymphocyte suspension containing B-cells (28%) and T-cells (72%) through the HA copolymer column, more than 60% of T-cells in 90% purity or more were recovered in the effluent.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220610
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  • 46
    Digitale Medien
    Digitale Medien
    Stability of performances of vascular prostheses retrospective study of 22 cases of human implanted prostheses (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 633-648 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Twenty-two cases of vascular graft failures (thrombosis, pseudoaneurysm, dilation, infection) were investigated by means of physicochemical, histological, and ultrastructural studies. A general decrease of mechanical resistance to stress of the prostheses was observed. Its magnitude ranged from 2 to 75% of the values of identical virgin prostheses and there was no relation with the duration of implantation. In addition to the breakage of yarn filaments (SEM), migration of fiber debris (histology) was observed in 7 cases. The structure of the polyester molecule had evolved after implantation. A decrease of crystallinity (x-ray diffraction and differential scanning calorimetry) was noted. These observations raise the question of the established stability of vascular prostheses and emphasize the need for further investigations in human graft retrieval programs.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220705
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  • 47
    Digitale Medien
    Digitale Medien
    Permeability of a heparin-polyvinyl alcohol hydrogel to thrombin and antithrombin III (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 673-685 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The diffusivities of thrombin and antithrombin III in a heparin-polyvinyl alcohol hydrogel were estimated and used to demonstrate that diffusion limits the effectiveness of the immobilized heparin in the interior of such hydrogels. Diffusivities were calculated from permeabilities and partition coefficients measured with films in a diffusion chamber apparatus. The diffusion coefficients were estimated to be 6 ± 4 × 10-8 cm2/s for thrombin and 4 ± 2 × 10-8 cm2/s for antithormbin III in 10% gel membranes with or without immobilized heparin. Using the diffusivity of thrombin and a Thiele-type modulus, the effectiveness factor of a spherical heparin-PVA bead used to accelerate the inactivation of thrombin by antithrombin III was found to be 4-9% (diameter range 250-105 μm). While indicating that diffusion of thrombin limited the full utilization of the immobilized heparin, these values for the effectiveness factor could not completely account for the low apparent heparin activity (0.2%) in a thrombin time test of heparin-PVA “beads” (J. Biomed. Mater. Res., 17, 359 (1983)). Other factors such as the immobilization chemistry or the diffusion of thrombin-antithrombin III complex must be considered for a full explanation of the thrombin time results.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220802
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  • 48
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 747-748 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220807
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  • 49
    Digitale Medien
    Digitale Medien
    Correlations between mouse 3T3 cell spreading and serum fibronectin adsorption on glass and hydroxyethylmethacrylate-ethylmethacrylate copolymers (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 763-793 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The interaction of cells with solid surfaces is important in many settings, including the response of tissue to implanted materials. Protein adsorption to the surfaces plays a critical role in controlling cell interactions with surfaces. However, few comprehensive studies of both cell behavior and protein adsorption in complex protein mixtures (e.g., serum) have been done so the connection between these events is not well understood. In particular, methods to systematically perturb both protein adsorption and cell behavior in order to understand their relationship have been lacking. To induce changes in cell and protein behavior, the effects of serum dilution and substrate surface chemistry were studied. Surface chemistry was varied by using a series of polymers and copolymers of hydroxyethyl methacrylate (HEMA) and ethylmethacrylate (EMA) varying in their hydrophobic/hydrophilic balance. Large changes in cell spreading and fibronectin adsorption were observed when either serum concentration or polymer type was varied. The spreading of 3T3 cells in serum was found to be well correlated with the amount of fibronectin adsorption to the substrates. Attachment was not correlated with fibronectin adsorption, especially on glass preadsorbed with diluted serum. For 3T3 cells and perhaps other cells that have a receptor for a protein which is present in the medium, the amount of adsorption of this protein to the substrate appears to be a critical factor controlling cell interactions with the substrate.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220903
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  • 50
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221001
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  • 51
    Digitale Medien
    Digitale Medien
    Component wear of total knee prostheses using Ti-6Al-4V, titanium nitride coated Ti-6Al-4V, and cobalt-chromium-molybdenum femoral components (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 887-903 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: A knee simulator was used to study the wear of carbon fiber reinforced UHMWPE(Poly Two) (Poly Two is a registered trademark of Zimmer, USA) tibial and patellar components against Ti-6Al-4V, titanium nitride (TiN)-coated Ti-6Al-4V, and cobaltchromium-molybdenum femoral components. The prostheses tested were regular sized Miller-Galante total knees mounted on 316L stainless steel fixtures using bone cement. An environmental chamber surrounded the knee and maintained bovine serum lubricant at 37°C. The specimens were tested using consecutive blocks of 464 level walking steps, 8 ascending stairs and 8 descending stairs for a total of 100,000 steps. The wear mechanisms found on the tibial components were scratching, carbon fiber associated damage, surface deformation, pitting, minor abrasion, and delamination. Three forms of carbon fiber associated damage were identified; fibers pulled from the surface, broken fibers, and UHMWPE removed from the surface fibers. The SEM evaluation revealed a pit forming mechanism. No correlation was found between femoral component material and tibial surface damage. Visual examination of the femoral components revealed no signs of wear or scratching on the cobalt-chromium-molybdenum or TiN-coated Ti-6Al-4V components. There were, however, many light surface scratches on the uncoated Ti-6Al-4V components, which were also observed in a supplementary test of an uncoated Ti-6Al-4V component tested with a conventional polyethylene tibial component.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221005
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  • 52
    Digitale Medien
    Digitale Medien
    Structure of a collagen-GAG dermal skin substitute optimized for cultured human epidermal keratinocytesSupported by NIH Grant GM 35068. (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 939-957 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Collagen and glycosaminoglycan (GAG) dermal skin substitutes (membranes) were studied as substrates for cultured human epidermal keratinocytes. Structure of dermal substitutes was optimized for pore size to promote ingrowth of fibrovascular tissue from the wound bed and for culture of human keratinocytes of the membrane's surface. Pore size of the freeze-dried material was regulated by control of the temperature of freezing between -50°C and -20°C and by concentration of starting materials between 0.17% and 1.62% wt/vol. A nonporous surface of collagen-GAG was laminated to the membranes to provide a planar substrate for cultured epidermal kerationocytes. Thickness of dermal substitutes was regulated by control of the volume and concentration of starting materials. Biotin was conjugated to solubilized collagen for binding with avidin of specific quantities of biologically active molecules. The optimized membranes are suitable substrates for the culture of human epidermal keratinocytes, and together with the cells yield a composite material that is histologically similar to skin.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221008
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  • 53
    Digitale Medien
    Digitale Medien
    Polymerization of multifunctional methacrylates and acrylates (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1011-1022 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The cross-linking reaction of 15 dimethacrylates, one trimethacrylate and five diacrylates was studied by means of differential scanning calorimetry (DSC) and high performance liquid chromatography (HPLC) to investigate the relationship between the polymerization characteristics and the chemical structure of these monomers. The amount of pendant double bonds (Dp) and the efficiency of cross-linking (Ec) were calculated from both the extent of polymerization (Ep) and the amount of residual monomer (Rm) obtained by DSC and HPLC analyses, respectively. The Ep and Ec values of various monomers increased with an increase in the number of chain members between the functional groups, while Rm and Dp values decreased. The dimethacrylates consisting of aliphatic chains polymerized more readily than those containing aromatic units. High Ep was obtained in the aliphatic dimethacrylates and diacrylates with more than eight chain members and the aromatic dimethacrylates with more than 20 chain members among the monomers examined. These results depend presumably on the flexibility of the functional groups in the polymer network. With most dimethacrylates and diacrylates, high Ep was also observed in thermal scanning polymerization compared to isothermal polymerization at 90°C. The diacrylates showed a high rate of polymerization compared to the corresponding dimethacrylates.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221105
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  • 54
    Digitale Medien
    Digitale Medien
    Erratum (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1083-1083 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221111
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  • 55
    Digitale Medien
    Digitale Medien
    An in vitro evaluation of the hemostatic activity of topical agents (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 149-157 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: An in vitro method has been developed for human non-anticoagulated blood to evaluate the enhancing effect of hemostatic agents on both plasmatic and cellular activation of the coagulation cascade. The coagulation time and the sequential generation of fibrinopeptide A (FpA) have been used as parameters. The kinetics of generation of FpA has been modelized and mathematically analyzed using the latence time, the slope of the linear part of the curve, and the time necessary to reach half maximal amplitude of FpA in the tube. A very precise evaluation of the hemostatic activity of five different molecules, four being collagenous in nature, is given.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220207
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  • 56
    Digitale Medien
    Digitale Medien
    Locking mechanism strength of absorbable ligating devices (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 179-190 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The locking mechanism strenghts of the absorbable Absolok and Lactomer ligating clips and the absorbable Lactomer staple have been determined following implantation in an animal model. Three sizes of each type of clip and the single size of staple were enclosed in open mesh nylon pouches and implanted subcutaneously in rabbits for periods of 4, 7, 14, 21, and 28 days before tensile testing of the lock mechanisms. No change in the lock mechanism strength was detected for the Absolok clips before 21 days. The Lactomer clips and staples, however, showed significant decrease in lock mechanism strength within 7 days of implantation, this loss increasing with longer implantation times. A proportion of all the devices were found to have dissolved to an extent that precluded testing at 21 and 28 days. The findings indicate that the lock mechanisms of absorbable ligating clips differ significantly in their short-term (30 days) durability.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220303
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  • 57
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 251-253 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220308
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  • 58
    Digitale Medien
    Digitale Medien
    Cell morphology, proliferation and collagen synthesis of human fibroblasts cultured on sepiolite-collagen complexes (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 257-270 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The growth and morphology as well as collagen biosynthesis of human fibroblasts obtained and cultured on sepiolite-collagen complexes have been studied. No differences on cell morphology and growth properties nor collagen synthesis were observed when compared with standard culture substrates. The type I/type III ratio of biosynthesized collagen by fibroblasts cultured on sepiolite-collagen complexes was about 5-6 with no difference when compared to control conditions. This normal behavior was also observed for the type I/type III procollagens. According to these studies the sepiolite-collagen complexes do not modify the studied features of the fibroblasts.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220402
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  • 59
    Digitale Medien
    Digitale Medien
    In vitro and in vivo metal ion release (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 321-338 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: A series of experiments was conducted to study in vitro and in vivo metal ion release and the urine excretion of metal ions. Metal salts were injected and urine analyzed. Anodic potentials were applied to stainless steel and cobalt-chromium-molybdenum (CCM) specimens to cause an acceleration of corrosion rates. Corrosion experiments were done in saline, 10% serum and in a subcutaneous space in hamsters. Corrosion rates were determined by measurements of weight loss and calculations of net charge transfer. Metal ion concentrations were determined with graphite furnace atomic absorption spectroscopy, and were calculated from total charge using Faraday's law. The results with stainless steel showed that the weight loss and metal ion release from stainless steel in vitro and in vivo can be calculated using Faraday's Law, assuming release in proportion to alloy composition. The results with CCM indicated that release rates in vitro can be used to determine the proportionality of release in vivo. All the nickel and most of the cobalt was rapidly excreted, while less than 50% of the chromium was excreted. The excretion of metals following salt injection or in vivo corrosion were very similar.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220406
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  • 60
    Digitale Medien
    Digitale Medien
    Mineralization and calcium fixation within a porous apatitic ceramic material after implantation in the femur of rabbits (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 445-457 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Cylinders (0.8 cm long, 1.0 cm of diameter and with an axial hole), constituted, after firing, of a ceramic mixture of hydroxylapatite (HA) and β-ricalciumphosphate (β-TCP) in a 10:1 ratio, were implanted into mid-diaphiseal defects of one femur of 20 rabbits and stabilized with intramedullary rods. The implantation sites were checked radiographically every month, and after 3 months (3 animals) and 6 months (17 animals) the rabbits were sacrificed and the implants with the surrounding tissue were embedded in methylmetacrylate, cut to thick sections and analyzed by scanning electron microscopy (SEM). Porosimetric and x-rays diffraction analyses were carried out before and after implantation of the cylinders, and the state of mineralization at the bone-implant interface was determined by EDAX microprobe analysis. Bony callus formation started at 1 month at the osteotomy sites, as judged by radiography, but after 3 months a not-mineralized zone had still been demonstrated between bone and the implants. At 6 months, 13 implants showed themselves firmly fixed in their implantations beds, while 4 implants were only incorporated at their proximal ends. In bone contact zones, an enrichment of Ca2+ was displayed by microanalytical techniques in the outer zone of the implanted samples which may be explained by an apparent additional phase transformation of HA into TCP, thanks to the change of the Ca/P ratio, that takes place in vivo.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220602
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  • 61
    Digitale Medien
    Digitale Medien
    Analysis of in vitro enzymatic and oxidative degradation of polyurethanes (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 509-527 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: In vitro biodegradation studies were performed to assess the long-term stability of poly(ether urethane) (PEU) implants. Three PEU's and one poly(ester urethane) were treated with enzymes characteristic of those released from inflammatory cells during the foreign body reaction. In addition, the effect of hydrogen peroxide was observed to examine oxidative degradation. Polymers were prepared as thin films on glass, gold, silver, and copper substrates to test the possibility of metal-catalyzed degradation. Molecular weights and polydispersities of the polymers were measured by gel permeation chromatography (GPC) before and after treatment. Changes in peak shape and location were also monitored. The results demonstrate that varying degrees of both enzymatic and oxidative degradation occurred.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220607
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  • 62
    Digitale Medien
    Digitale Medien
    Estimation of surface-bound heparin activity: A comparison of methods (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 497-508 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: We compared two assays for estimating the amount of active heparin bound to a catheter surface: (1) a kinetic assay based on the inactivation of thrombin by antithrombin III, and (2) thrombin uptake. Both assays were used to estimate the amount of heparin activity on a series of catheters coated with no heparin, covalently bound heparin, and ionically bound heparin. The kinetic assay produced estimates of surface-bound heparin activity and showed that some binding methods resulted in destruction of most of the heparin's biologic activity. In contrast, the thrombin uptake assay did not correlate with the amount of heparin activity on the catheter surface. Substantial thrombin uptake was found on surfaces coated with no heparin or inactive heparin, while low thrombin uptake was found on surfaces with high levels of heparin activity in the kinetic assay. We conclude that: (1) a kinetic assay based on the heparin accelerated inactivation of thrombin by antithrombin III can be used to estimate the amount of active heparin bound to a catheter surface, and (2) thrombin uptake studies do not correlate with heparin activity and do not predict which heparin binding method will result in the highest concentration of active heparin on the catheter surface.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220606
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  • 63
    Digitale Medien
    Digitale Medien
    Thermomechanical study of Ni-Ti alloys (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 573-588 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: A preliminary study was conducted to demonstrate the usefulness of the combined technique of differential scanning calorimetry (DSC) and mechanical testing for the shape memory metals of 54NiTi and 53NiTiCo(3%) alloys. The DSC technique was used to measure precise transformation temperatures and the amount of thermal energy required for the corresponding phase transformation. The degree of plastic deformation by bending and the effect of alloying (such as Co) were studied with combined DSC and mechanical property measurements.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220611
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  • 64
    Digitale Medien
    Digitale Medien
    A study of the nature and formation of zinc polyacrylate cement using Fourier transform infrared spectroscopy (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 623-631 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The formation and structure of zinc polyacrylate has been studied by Fourier transform infrared spectroscopy (FTIR). Using this technique we have shown that the fully hardened cement is bonded predominantly by zinc carboxylate complexes, rather than by associations of purely ionic character as had previously been supposed. Ionic bonds are formed in the initial stages of the reaction but are gradually converted to complex forms. This bond rearrangement appears partly responsible for physical changes that occur during gelation, setting, and hardening.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220704
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  • 65
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220801
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  • 66
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220901
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  • 67
    Digitale Medien
    Digitale Medien
    Effect of delay between tissue harvest and glutaraldehyde pretreatment on mineralization of bovine pericardium used in bioprosthetic heart valves (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 819-825 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: There is concern that delayed glutaraldehyde treatment of bioprosthetic tissue could potentiate calcification by autolytic generation of mineralization nuclei. This study investigated the effects on mineralization of variable delays between harvest of bovine pericardium and initial glutaraldehyde treatment, using tissue implanted subcutaneously in rats for 21 days. Susceptibility to mineralization increased statistically but only modestly with delays to 34 h. This suggests that mineralization will not be significantly inhibited by rapid treatment of otherwise properly handled tissue and that clinically important prevention of calcification will require more dramatic means.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220905
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  • 68
    Digitale Medien
    Digitale Medien
    Influence of blood flow and the effect of protamine on the thromboresistant properties of a covalently bonded heparin surface (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 859-868 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Polyethylene tubings, 2-mm inner diameter and the length of 1 m, untreated or furnished with a covalently bonded heparin surface layer, were inserted as arterio-venous shunts bilaterally in dogs. By compressing the middle part, the initial blood flow was adjusted to 10 or 40 mL/min. The thrombogenecity of the tubings was assessed by the patency of the shunts and by assaying the generation of fibrinopeptide A (FPA) in arterial blood and in blood after its passage through the shunts. In untreated shunts clotting rapidly occurred preceded by high FPA generation in blood passing through the shunts. The blood flow in heparinized shunts remained unchanged throughout the test period. At the low flow rate a certain degree of FPA generation in the shunts occurred. At the high flow rate no changes in FPA levels occurred. The function of the heparin surface is thus flow rate dependent. Systemtic heparinization and subsequent neutralization with protamine or administration of protamine alone did not interfere with the function of the heparin surface.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221003
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  • 69
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 959-960 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221009
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  • 70
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221101
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  • 71
    Digitale Medien
    Digitale Medien
    In situ polymerization of a microencapsulating medium round living cells (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1061-1070 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: A new process for microencapsulating living cells is described. Pancreatic islet cells in solution in agarose were extruded from a syringe into a paraffin-oil-containing medium. A rigid interface around each bead was produced when the agarose gelled. A polymerizable mixture of monomers containing 30% of acrylamide and 1.5% of bisacrylamide was then added to these beads. Polymerization was initiated by a photochemical process using riboflavin as a photosensitizer, which enabled use of oxygenated solutions. As other polymerizations initiated by an oxido-reduction reaction, this method did not require heating, and could thus be carried out at ambient temperature. The oil phase near the agarose beads effectively prevented any rise in temperature, and also led to formation of an acrylamide concentration gradient in the aqueous phase, which reduced the potential cytotoxicity of the reaction. Radioimmunoassay of insulin liberated from encapsulated islets of Langerhans demonstrated a good viability of the cells.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221109
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  • 72
    Digitale Medien
    Digitale Medien
    In vitro characterization and biomechanical optimization of a biodegradable particulate composite bone cement (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1071-1082 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: We have developed a biodegradable particulate composite bone cement and used in vitro and in vivo methods for studying its suitability for orthopaedic applications. The composite matrix consists of gelatin, water, and sodium salicylate. The particulate phase is made up of powdered and particulate (355-600 μm diameter) tricalcium phosphate. Paraformaldehyde (0.1% to 0.5% by weight) is used as a matrix cross-linking agent. The effects of incubation time, particulate volume fraction, density of the individual particles, water content, concentration of crosslinking agent, and freeze-drying on the unconfined compressive strength and modulus of the particulate composite were measured. Compressive strengths of 7 MPa and moduli of 65 MPa could be achieved. Mechanical properties depended critically upon the water content of the particulate composite, with values of strength and modulus decreasing rapidly outside a range of 10-14% of specimen dry weight. High-density tri-calcium phosphate particulate produced cement with twice the strength found with porous particulate. In a companion study we document in vivo performance of this particulate composite in an animal model system.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221110
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  • 73
    Digitale Medien
    Digitale Medien
    Editorial (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. iii 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220102
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  • 74
    Digitale Medien
    Digitale Medien
    AES analysis of stainless steel corroded in saline, in serum and in vivo (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 31-44 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Auger electron spectroscopic (AES) studies were conducted to examine the surface film of stainless steel specimens which had been subjected to passive and anodic corrosion in vitro and in vivo. Anodic corrosion was accelerated by the application of a +500 mV (SCE) potential for 30 minutes. Experiments performed in 0.9% saline indicated little alteration in the nature of the surface film compared to a freshly prepared control specimen. Auger analysis of specimens in 10% serum or in vivo revealed that passive film thickness was dependent on the corrosive environment. The films of specimens immersed under freely corroding conditions in 10% serum or in vivo were similar to the control film. Accelerated corrosion performed in 10% calf serum resulted in significant film thickening. The thickest films were from accelerated corrosion in vivo. The mechanism for the altered surface films produced by corrosion in vivo or in serum as compared to saline needs to be investigated further.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220105
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  • 75
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220201
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  • 76
    Digitale Medien
    Digitale Medien
    Effect of proteins and pH on fretting corrosion and metal ion release (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 111-120 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The objectives of this study were to determine the effect of proteins and protein charge on the corrosion of stainless steel. As Zwitter ions, proteins have a positive charge in solutions acidic to their isoelectric point (pI) and a negative charge in solutions basic to the pI. Fretting corrosion rates of stainless-steel plates and screws as determined by weight loss and metal ion release were studied in saline and protein solutions with the pH adjusted to 3, 5, and 8. Alterations in pH did not affect the corrosion rate in saline solutions. However, alterations of the pH in albumin solutions did affect the corrosion rate. In protein solutions acidic to the isoelectric point the presence of the positively charged albumin did not alter the corrosion rates as compared to that in saline. However, the presence of negatively charged proteins in solutions basic to their isoelectric points decreased the amount of corrosion. Thus, the effect of proteins on fretting corrosion is dependent on the charge on the protein. When the release of nickel was compared to the release of chromium, it was shown that the release was in proportion to the composition of the alloy when fretting corrosion took place in saline. The nickel/chromium ratio in the albumin and gamma globulin solutions was increased relative to that predicted indicating preferential release of nickel in protein solutions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220204
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  • 77
    Digitale Medien
    Digitale Medien
    Quantitative analysis of early in vivo tissue response to synthetic apatite implants (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 137-148 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Studies have shown synthetic calcium phosphates such as hydroxyapatite and beta tricalcium phosphate to be biocompatible in vivo. However, few studies have quantitated histological responses to the implants.The aim of this study was to develop a method for the quantitative assessment of tissue biocompatibility to ceramic materials in vivo and to use this method to compare noncarbonated and carbonated apatite implants. Synthetic sintered apatites of 0, 3, and 6% carbonate by weight were prepared and cut into implants 4 × 4 × 1 mm. These were placed 2 mm into the medial aspect of rat fermurs. Following sacrifice at 4 weeks, the femurs were fixed in formalin, demineralized in formic acid, and embedded in glycol methacrylate. Sections were cut on an ultramicrotome set at 1.5 μm and stained with toluidine blue. A point counting technique using standard stereological grids and a low-power microscope was used to measure areas of new bone formation. The width of the connective tissue zone adjacent to muscle was measured using an image analyzer. All implants were well accepted by the host tissues judging from criteria of minimal inflammation and degree of fixation. Results showed an increase in new bone formed in the marrow cavity with increasing carbonate content. This may improve stability of the implant in the host bone, particularly during the initial healing period. A technique which should enable quantitative histological evaluation of different ceramic materials has been developed. The use of this method indicates that further studies are warranted to investigate carbonated apatite as an implant material.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220206
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  • 78
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988) 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220101
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  • 79
    Digitale Medien
    Digitale Medien
    Molecular and supramolecular structure of adsorbed fibrinogen and adsorption isotherms of fibrinogen at quartz surfaces (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1-11 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The adsorption of fibrinogen to quartz surfaces was measured by ellipsometry, ELISA, and electron microscopy. The initial adsorption at low concentrations was diffusion rate limited as determined by the ELISA and by counting the number of adsorbed molecules at electron micrographs. From ellipsometry, ELISA, and electron microscopy measurements it was found that the surface concentration of adsorbed fibrinogen increased continuously over four decades in bulk concentration of fibrinogen. At a hydrophilic quartz surface a plateau level of the adsorption isotherm was found at a surface concentration of 0.1 pmol/cm2 where the adsorbed molecules had a mean intermolecular distance of 10 ± 5 nm between neighbors. At higher surface concentrations the molecules were densely packed and formed a layer where single molecules could not be identified. Adsorbed fibrinogen showed different structure at hydrophobic and hydrophilic quartz surfaces. At a hydrophilic surface, the fibrinogen molecules appeared as a 46 nm nodose rod consisting of 6-7 nodes with a diameter of 4 nm. At a hydrophobic surface, the molecule appeared as a binodular or trinodular rod with a node diameter of 5-9 nm, connected with a thin filament to form a 40-nm rod. Adsorption from higher concentrations of fibrinogen in solution resulted in adsorbed spheric structures with a diameter of 18-24 nm at the hydrophobic surface and in end-to-end polymers at the hydrophilic quartz membrane.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220103
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  • 80
    Digitale Medien
    Digitale Medien
    Announcements (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 81-83 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220109
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  • 81
    Digitale Medien
    Digitale Medien
    The tensile strength of natural and chemically modified bovine pericardium (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 89-98 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Nondestructive and destructive uniaxial load tests were performed on natural and chemically modified bovine pericardium. Five specimens were selected from the same sites in different pericardial sacs by using a template. The mean maximum extension of one particular site in both the natural and chemically modified material was significantly greater than that of the other positions at a stress level of 0.6 Nmm.-2 The maximum extensibility of the fixed tissue was significantly greater (p 〈 0.01) than that of the natural tissue. There was also an anatomical variation in tensile strength of the natural material which was retained after chemical modification. However, the overall tensile strength of the pericardium was not increased by this procedure. In contrast, glutaraldehyde fixation did increase the percentage strain at which fracture of this biomaterial occurred.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220202
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  • 82
    Digitale Medien
    Digitale Medien
    Biodegradable PEO/PLA block copolymers (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 993-1009 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Poly(ether ester) block copolymers based on polyethylene oxide (PEO) and polylactic acid (PLA) segments were synthesized and characterized, with the aim of developing a new family of bioabsorbable polymers. The materials developed were tailored to meet various mechanical and degradation requirements, and overcome the limitations of the few existing biodegradable polymers. The copolymeric matrices were characterized by means of infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy. The composition of the copolymers synthesized varied between 20 and 84 mol% lactic acid, with PEO chains in the 600-6000 molecular weight range. The solubility properties of the copolymers in a series of organic solvents are described. The equilibrium water content and the water contact angle of various matrices were determined and related to their composition and structure. The incorporation of PEO into the chain yielded highly hydrophilic materials, with equilibrium water contents higher than 60%. Stress/strain curves are presented.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221104
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  • 83
    Digitale Medien
    Digitale Medien
    Apatite-wollastonite containing glass ceramic-fibrin mixture as a bone defect filler (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 869-885 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The purpose of this study was to evaluate the usefulness of a mixture of apatitewollastonite containing glass ceramic (A-W · GC, 42-60 mesh in granule size) with fibrin as a bone defect filler. A bone defect was drilled in the proximal metaphysis of the rat tibia and was filled with (1) fibrin glue, (2) A-W · GC granules, or (3) A-W · GC-fibrin mixture. Nothing was placed in the defect of the controls. The animals were serially sacrificed until 8 weeks after the operation, and the defect site was histologically examined and histomorphometrically analyzed for quantitative evaluation of newly formed bone and blood vessels. The use of fibrin glue as the binder markedly increased the ease of handling the A-W · GC granules. In the controls, little trabecular regeneration was observed in the defect site. Early vascularization (confirmed by microangiography) increased and the repairing process was accelerated in the defects filled with fibrin. In these defects filled with A-W · GC granules, good bone formation was observed around the granules. Bone formation was accelerated in the defects filled with A-W · GC fibrin mixture. Thus, the mixture showed good osteoconductive potential as well as acceleration of the repair process. Therefore, A-W · GC-fibrin mixture is considered to be a useful bone defect filler.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221004
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  • 84
    Digitale Medien
    Digitale Medien
    Cell growth on metallic glasses: The interaction of amorphous metal alloys with cultured neuronal, osteoblast, endothelial, and fibroblast cells (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 905-917 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Ferrous based, corrosion resistant amorphous alloys supported the adhesion and growth of cultured chick neuronal cells, human marrow stromal cells (presumptive osteoblasts), bovine aortal endothelial cells, and hamster kidney fibroblasts. Alloys of compositions Fe60Ni10Cr10P13C7, Fe70Cr10P13C7, and Fe70Cr10P13B7 were found to be suitable. In contrast the crystalline form of these alloys was markedly less effective. Outgrowth of neurites from neuronal cells was promoted by precoating the metal surface with either laminin or neurite promotion factor. The adhesion of osteoblasts and fibroblasts suggests that corrosion resistant metal glasses should be considered as biomaterials useful for orthopedic applications. The adhesion of neuronal cells accompanied by neurite outgrowth indicates that the system might provide a functional interface between the neuromuscular system and an electromagnetic material that could be useful in bionic engineering.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221006
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  • 85
    Digitale Medien
    Digitale Medien
    Heparin immobilization onto segmented polyurethaneurea surfaces - effect of hydrophilic spacers (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 977-992 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Heparin was immobilized onto segmented polyurethane-urea surfaces (Biomer) using hydrophilic poly(ethylene oxide) spacers of different chain lengths. The use of the hydrophilic spacer, poly(ethylene oxide), reduces protein adsorption and subsequent platelet adhesion on the surface. In addition, the bioactivity of the immobilized heparin is enhanced by the incorporation of these spacers. Immobilized heparin bioactivity is shown to be a function of PEO spacer length. Use of hydrophilic PEO spacers demonstrates that immobilized heparin's bioactivity is consistently higher than that of the C6 alkyl spacer, but heparin-immobilized surfaces demonstrate no chain length effect on platelet adhesion, even though they show less platelet adhesion compared to Biomer controls. In the case of PEO-grafted surfaces, platelet adhesion is decreased compared to Biomer controls, and C6 alkyl spacer-grafted surfaces, and exhibits a minimum at PEO 1000. In ex vivo A-A shunt experiments under low flow and low shear conditions, all heparinized surfaces exhibit significant prolongation of occlusion times compared to Biomer controls, indicating an ability of immobilized heparin to inhibit thrombosis in whole blood.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221103
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  • 86
    Digitale Medien
    Digitale Medien
    The society for biomaterials symposium on retrieval and analysis of surgical implants and biomaterials August 12, 13, 14, 1988, Snowbird, Utah USA (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 125-132 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221305
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  • 87
    Digitale Medien
    Digitale Medien
    Fatigue testing of acrylic bone cements: Statistical concepts and proposed test methodology (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 179-190 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: In order to determine the fatigue behaviour of a material, a standard procedure and methodology must be proposed and validated. This article describes a standard test method and statistical analysis for describing the fatigue properties of acrylic bone cement. It is proposed that bone cement fatigue data can be subjected to probability of failure (P) analysis and the establishment of a distribution function describing the data. It is also proposed that an Olgive type curve can be used to describe the stress (S) vs. cycles to failure (N) data. These two data sets can then be combined to determine the P-S-N relationship which fully describes the fatigue characteristics of the material.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221309
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  • 88
    Digitale Medien
    Digitale Medien
    Applied biomaterials standards report (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 213-214 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221402
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  • 89
    Digitale Medien
    Digitale Medien
    Physicochemical characterization of deposits associated with HA ceramics implanted in nonosseous sites (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 257-268 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Pellets of well-characterized microporous hydroxyapatite (HA) ceramic were implanted in hamsters in two nonosseous sites: (1) in the fatty tissue of the gingival crease, far from bony tissue and (2) in intraperitoneal sites. The implants in site 1 were placed directly in contact with tissues, cells, and extracellular fluids while the implants in site 2 were placed in special chambers made of plexiglass cylinders covered in both ends with millipore filters, preventing contact with tissues and cells, but not with extracellular fluids. The hamsters were sacrificed and the implants recovered after 8, 16, 30, 150, and 365 days. The pellets were characterized using x-ray diffraction, infrared absorption, thermogravimetry, scanning and transmission electron microscopy, and calcium and phosphate analyses before and after implantation. Physicochemical analyses of HA ceramic implants before and after implantation demonstrated the formation of new material which was significantly different from the HA ceramic in terms of the following: (a) morphology (size of shape) of crystals; (b) intimate association of the inorganic phase of the new material with an organic phase similar to inorganic/organic association in bone; (c) the inorganic phase of the new material is a CO3-apatite, similar to that of bone, while the HA in ceramic is CO3-free; (d) electron diffraction of apatite of new material is similar to that of bone apatite. This study also demonstrated that the new material associated with the HA ceramics implanted in two different nonosseous sites were identical in spite of the differences in their microenvironment (cellular and acellular).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221406
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  • 90
    Digitale Medien
    Digitale Medien
    Strength of bonding between A-W glass-ceramic and the surface of bone cortex (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 327-338 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: We examined the bonding strength of apatite- and wollastonite-containing glass-ceramics (A-W · GC) to the surface of bone cortex. Semi-column-shaped blocks of A-W · GC were fixed with screws on the surface of the tibiae of rabbits. The blocks of alumina-ceramic were used as the control. The load required to detach the implant from the surface of bone cortex was measured 2, 4, 8, and 25 weeks after the implantation. The bonding strength between A-W · GC and the surface of bone cortex increased with time. It increased remarkably 4 weeks after the implantation, suggesting that the chemical bonding advanced rapidly between 2 and 4 weeks after the implantation. The tensile strength of bonding reached a maximum of 15.1 ± 3.1 kg/cm2 25 weeks after the implantation. The shear strength of bonding reached a maximum of 17.1 ± 2.3 kg/cm2 25 weeks after the implantation. From these studies, we conclude that A-W · GC has a capability of making relatively quick bonding to the surface of bone cortex.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221410
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  • 91
    Digitale Medien
    Digitale Medien
    Designing to counteract the effects of initial device instability: Materials and engineering (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1127-1136 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Implants for hard tissue replacement have evolved over the last few decades, but a critical assessment of their design reveals that most dental implants and most orthopedic appliances for any given indication are basically similar in design to their commercial competitors. Some unique features are contained in the outer 0.7 mm, but shadow pictures of the devices could almost be superimposed upon one another. Near-optimal designs have evolved for the materials systems commonly in use. The fight to minimize initial instability of implants, which leads to failure, has caused certain attachment mechanisms to emerge as acceptable, based upon research that indicates firm fixation in bone has resulted in longer average implant lifetime. The problem of initial stabilization is one of materials and design, both of which are necessary for a successful implant system. The nonmetallic calcium phosphate glass and ceramics technology available today provides materials that may counteract the effects of initial device instability by not relying on mechanical means of retention, alone, but chemical as well.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221206
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  • 92
    Digitale Medien
    Digitale Medien
    A comparative clinical study of solid and granular porous hydroxylapatite implants in human periodontal osseous defects (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1233-1243 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Solid and granular porous hydroxylapatite implants were compared in the surgical treatment of angular interproximal periodontal defects in 10 subject. After completion of initial therapy, presurgical measurements of pocket depth, attachment level, gingival recession, gingival fluid and tooth mobility were recorded. Six months after the surgery the measurements were repeated. The use of both forms of porous hydroxylapatite resulted in reduction in pocket depth, and probebale attachment level gains as well as gingival recession and reduction of gingival fluid and tooth mobility. These changes were similar for both granular and solid forms of porous hydroxylapatite.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221211
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  • 93
    Digitale Medien
    Digitale Medien
    Abridged report of the committee to survey the needs and opportunities for the biomaterials industry (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 1267-1291 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221213
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  • 94
    Digitale Medien
    Digitale Medien
    FDA - Medical device news corner (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 119-123 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221304
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  • 95
    Digitale Medien
    Digitale Medien
    Biomaterials for facial bone augmentation: Comparative studies (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 159-177 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Presently no material is available which is entirely satisfactory for facial bone augmentation. These studies examine several of those already in clinical use, made from various polymers in solid, porous, and woven forms. Homograft bone has also been studied, as an implant material. All materials were used in situations for which they are currently recommended clinically. Bioglass (Bioglass is a trademark of the University of Florida) implants, which are suggested for clinical use, have been studied in the same model and results show that their surface activity provides a more satisfactory immobilization, both in the short and long term, than does the tissue ingrowth on which most of the other materials depend. Results show that in this model as well as in clinical practice, porous and woven materials provoke in tissues a continuing cellular response which will always compromise long-term clinical success. Autograft bone has associated morbidity and is unpredictable with respect to its incorporation into host tissue and persistance at the site. Bioglass, however, was immobilized successfully at both hard and soft tissue interfaces without the need for porosity, could be satisfactorily shaped in the operating room, and, in addition, had the bonelike hardness which is not provided by any other available material.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221308
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  • 96
    Digitale Medien
    Digitale Medien
    Fatigue properties of acrylic bone cement: S-N, P-N, and P-S-N data (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 221-244 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The determination of the fatigue properties of a material is a fundamental criteria in the engineering design process. The fatigue properties are governed by a number of factors, one of which is the inherent scatter in the data. In order to take into account this scatter in the results, the concept of the probability of failure (P) is introduced and interconnected with the well known stress (S) versus number of cycles to failure (N) data. This report determines the S-N curve, P-N curve, and P-S-N contour for the three leading acrylic bone cements: Surgical Simplex P, Zimmer LVC, and Zimmer Regular. Tensile specimens were fabricated according to ASTM D638 specifications and tested in uniaxial, zero-tension fatigue. The resulting stress versus number of cycles to failure data was subjected to a nonlinear least-squares analysis to determine the mathematical expression of the fatigue curve. Statistical analysis showed excellent fit of the data to the predicted curve for estimation of the endurance limit of each cement. The results indicated that Zimmer LVC had the highest endurance limit while the limit of Simplex-P and Zimmer Regular were significantly lower. No significant difference was noted in the endurance limit between Simplex-P and Zimmer Regular. The probability of failure at each stress level was determined with respect to fatigue distribution functions. Using the normal distribution function and previous S-N data, the P-S-N contour was generated for each cement. The P-S-N contour fully describes the fatigue characteristics of the material.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221404
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  • 97
    Digitale Medien
    Digitale Medien
    Material properties of living soft tissue composites (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 311-326 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Collagen sponges seeded with fibroblasts have been used as a soft tissue substitute in wound healing applications. This biomaterial is a good in vitro analog of a connective tissue. Therefore, analysis of the properties of this material may be useful for theoretically modeling soft tissues. Stress-strain curves for such cell-seeded collagen sponges were measured to determine composite stiffness and ultimate tensile strength. Theoretical modeling was done by defining a particle-reinforced matrix using the composite sphere model. A system of uniaxially oriented fibers was then introduced to this equivalent homogeneous media and material properties were determined using the composite cylinder model. Geometric averaging was performed to yield the stiffness and Poissons' ratio for a composite with randomly oriented fibers. Inputs to the model were constituent material properties, cell volume fraction, and fiber volume fraction. From theoretical results, material properties of soft tissues and their substitutes depend on fiber mechanical properties and volume fraction and not cellular mechanical properties and volume fraction. Therefore, the increase in experimentally observed composite stiffness with increased cell number was due to deposition of newly synthesized stiffer collagen fibers, and not due to the physical presence of cells themselves.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221409
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  • 98
    Digitale Medien
    Digitale Medien
    Letters to the editor (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 351-356 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820221412
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  • 99
    Digitale Medien
    Digitale Medien
    Physical and hydrodynamic factors affecting erythrocyte adhesion to polymer surfaces (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 13-29 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Using a flow cell design which ensures fully developed laminar flow, the influence of various hydrodynamic and physical factors in determining the extent of erythrocyte adhesion to various polymer surfaces has been examined. Specifically we have investigated the effect of exposure time, flow rate, erythrocyte concentration, and substrate surface tension on the extent of erythrocyte adhesion. The results indicate: (1) the extent of erythrocyte adhesion is most extensive on the more hydrophobic surfaces; (2) the rate of adhesion is higher on the more hydrophobic surfaces; (3) saturation coverage occurs after 7-10 min of exposure to the erythrocyte suspension for all substrates examined. No „lag-time“ in the onset of adhesion was observed; (4) The level of saturation depends on the bulk erythrocyte concentration, increasing with increasing cell concentration; (5) the extent of adhesion decreases with an increase in flow rate; and (6) substrate surface defects such as roughness have a major effect on the pattern of erythrocyte adhesion.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220104
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  • 100
    Digitale Medien
    Digitale Medien
    Hydrophilic microporous polyurethane versus expanded PTFE grafts as substitutes in the carotid arteries of dogs. A limited study (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 63-69 
    Details
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: A novel, microporous, hydrophilic polyether urethane-urea (PEUU) vascular graft was compared with expanded PTFE in the canine carotid artery. At implantation times ranging from 4 h to 6 months, all the PEUU grafts were found to be occluded while of the PTFE grafts, only those implanted for 1 week and 6 months were blocked. Histopathological analysis of the explanted grafts and their capsules revealed an on-going inflammatory reaction at the anastomotic sites of the PEUU grafts.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jbm.820220107
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