摘要:

AbstractSeveral metallic orthopedic implants which failed in service and for which the medical histories are known are comprehensively examined using metallographic techniques and electron microprobe analyses to determine the causes of failure. The results indicate that fatigue is a major cause of failure and that, in all probability, the fatigue is initiated by poor design or poor material.

ISSN:0021-9304    

DOI:10.1002/jbm.820020102

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractThe effect of phenol and certain phenyl compounds on the different stages of the blood coagulation and fibrinolytic mechanism is investigated. Phenol has a complex action on blood coagulation. In an optimal concentration of 0.3% it produced a definite, though suboptimal platelet factor 3 activity, evolved factor XII, accelerated thrombin–fibrinogen interaction, retarded clot retraction, enhanced the action of streptokinase on plasminogen, and inhibited plasmin. In addition, in the absence of factor XIII and calcium, it increased the solubility of fibrin in urea. Phenyl acetaldehyde, benzyl benzoate, and styrene (phenyl ethylene) accelerated stypven clotting time and thrombin–fibrinogen reaction. Unpolymerized styrene and phenyl ethanol specifically inhibited the action of plasma thromboplastin, formed in a system lacking in factor VIII or IX. A study is also reported on the changes responsible for the stabilization with phenol of brain thromboplastic activity. The action is not purely bactericidal, but is dependent on the presence of brain tissue particles in suspension. The contribution of platelets to plasma thromboplastin formation is examined in the light of these investigations, showing the ability of phosphorus‐free compounds to supply a platelet‐like a

ISSN:0021-9304    

DOI:10.1002/jbm.820020103

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractTubing made of a polar plastic, polychlorotrifluoroethylene, was electrically polarized while heated. The zeta potential of tubes polarized negatively inside was consistently higher than that of unpolarized tubes. Tubes polarized positively had a much smaller and variable change in zeta potential. The change is apparently not related to the formation of electrets, but may be due to the orientation of pre‐existing dipole

ISSN:0021-9304    

DOI:10.1002/jbm.820020104

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractBioelectric charge transfer at the blood–wall interface may be a crucial factor affecting thrombosis on implant materials. A program of studies was conducted to determine the electrokinetic and other physical properties of a wide spectrum of materials including organic polymers, metals, inorganics, heterogeneous compounds, and animal tissue. From these tests, materials were selected forin‐vivocannulation experiments. In this manner, a search was made to find a correlation between surface charge characteristics and thrombosis on cardiovascular implant materials. It was found that materials exhibiting a substantial positive charge were prone to rapid thrombosis. No clear correlation can be stated, as yet, regarding the thrombogenecity of highly charged negative surfaces or slightly charged surfaces. However, many heterogeneous materials have exhibited prolongedin‐vivopatency. It appears necessary to isolate surface effects from volumetric effects to seek the role of bioelectric charge transfer in blood thrombus form

ISSN:0021-9304    

DOI:10.1002/jbm.820020105

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractAdult albino rabbits were implanted with disks of 316 and 304 stainless steel in the subperiosteum of the anterior calvarium and the left mandible and in the left paravertebral and thigh muscles. The corresponding opposite sites were sham operated. The histopathological slides revealed that there was variation in thickness of the membrane in sections of both the paravertebral and thigh muscles; one side showing greater reaction than the other, which corresponded with the appearance of the implants. Sections of the calvarium revealed minimal bone and soft tissue reaction, although the implants showed corrosion compatible with soft tissue sites. The mandibular sections revealed extensive bone tissue reactions with minimum masseter muscle reactions, but the appearance of the implants due to corrosion was different than those of all other sites. Moderate eosinophilic infiltration was observed in sections containing deposits of corrosion products.

ISSN:0021-9304    

DOI:10.1002/jbm.820020106

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractAn alternate correlation of blood coagulation time with surface properties of solids is proposed in that the work of adhesion is used rather than the surface free energy. The overall quality of the two correlations is about the same, but the new method does allow the important data point for glass to also be included. Possible useful future work of this type is discussed.

ISSN:0021-9304    

DOI:10.1002/jbm.820020107

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractThe effects of variations in composition and processing on the open‐circuit electrode potentials measured as a function of time of amalgams made from silver–tin, silver–tin–copper, silver–tin–zinc, and silver–tin–copper–zinc alloys have been determined at 37°C in distilled water, in saline solution, as well as in acetate and citrate solutions buffered to pH values of 3, 7, and 10. The electrochemical potentials of the alloys measured as a function of time in neutral acetate solutions show anodic polarization from an initial cathodic potential value of approximately 0.1 v with respect to the standard hydrogen electrode to a constant potential level depending upon alloy composition. In neutral acetate solution the potential–time curves of silver–tin amalgams with 7:5 mercury to alloy ratio show a rapid anodic polarization from an initial anodic potential value of 0.28 v to a minimum value of 0.05 v at approximately 1 hr followed by a potential reversal to a plateau value of 0.40 v. For 7:5 amalgams in neutral acetate solutions increases in both the trituration time and in the severity of processing deformation cause a small increase in initial potential, with a decrease in anodic polarization, while an increase in amalgam age lowers both the initial potential value and the longer‐time potential plateau. Increasing the mercury content of the amalgam to a 2:1 ratio decreases the rate of potential reversal from the minimum, whereas decreasing the ratio to 4:5 decreases the amount of depolarization from the minimum value. The effects of copper and zinc additions to silver–tin alloys are mixed. In neutral acetate solution the 7:5 ratio amalgams from silver–tin–copper alloys show anodic polarization from the same initial value as the silver–tin amalgams, followed by a region of decreased polarization. Both silver–tin–zinc and silver–tin–copper–zinc alloys exhibit a much higher initial anodic potential (0.78 v), and following the achievement of the potential plateau have a slow anodic polarization to the long‐time potential value shown by silver–tin amalgam. Three commercial alloy amalgams were studied in neutral acetate solution. The two amalgams containing zinc have a potential behavior similar to that of the experimental zinc‐containing amalgam; the non‐zinc amalgam shows a rapid anodic polarization from an initial anodic potential value of 0.24 v, a minimum at 1 hr, and a reversal to the long‐time potential v

ISSN:0021-9304    

DOI:10.1002/jbm.820020108

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractA segmented polyurethane elastomer, originally developed for elastic thread, is now being used for molded prostheses. Chemical, mechanical, and biological properties are described. Hydrolytic stability of this polymer is compared to that of a polyester urethan. Experience with the material used in components of an experimental heart‐assist pump has shown excellent flex endurance, wear resistance, and intravascular acceptabilit

ISSN:0021-9304    

DOI:10.1002/jbm.820020109

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractDuring the period covered by this investigation, toxicological studies were carried out in hamsters and rabbits. The results of injections, subcutaneously and in the buccal pouch of hamsters, indicated that the silicones used were nontoxic, non‐absorbable, and well encapsulated by connective tissue elements with moderate tissue reaction. Further studies of various combinations of roomtemperature vulcanizing silastics indicated similar reactions when injected submucosally in the alveolar ridges and palate of rabbits. The injected materials remainedin situin the injected submucosal area and became well encapsulated by the proliferation of connective tissue and collagenous fibers. There was no evidence of macrophages or foreign body giant‐cells in and around the proliferating connective tissue capsule. There were no macroscopic or microscopic signs of tumor formation. The encapsulated masses did not elicit bone resorption when localized adjacent to bone tis

ISSN:0021-9304    

DOI:10.1002/jbm.820020110

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY

摘要:

AbstractPolyelectrolyte complexes are ionic hydrogels formed by the coreaction of two oppositely charged, strongly ionized polyelectrolytes. While insoluble in simple solvents and infusible, these polymers can be fabricated into membranes, fibers, and other shaped articles by casting from ternary solvents. Homogeneous membranes are optically clear, amorphous structures in which the equilibrium gel water content can be controllably varied from ca. 30–90%. The net ion‐exchange capacity of the membrane can be varied from zero to ca. 2.0 meq/g, either cationic or anionic. Homogeneous membranes are characterized by unusually high water and gas permeabilities and permeabilities to water and soluble solutes which can be controlled by adjustment of gel water content and ion‐exchange capacity. Anisotropic membranes can also be prepared which are high flux molecular ultrafilters for solutes as small as sucrose. The anisotropic membranes have found widespread use in biology for fractionation, concentration, and purification of biopolymers. Homogeneous membranes show promise as analogues for biological membranes. A number of applications are being evaluated in medicine and surgery. These include: vascular grafts, antithrom‐bogenic coatings for plastic prostheses, contact lenses, corneal implants, and surgical adhesives. In addition, polyelectrolyte complex membranes are showing considerable promise for artificial kidneys and blood oxyg

ISSN:0021-9304    

DOI:10.1002/jbm.820020111

出版商:John Wiley&Sons, Inc.    

年代:1968

数据来源: WILEY