bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bio‐Compatibility in selection of materials for implantation
Authors: Homsy Charles A. 
Published: December 2004

AbstractIn this paper the factors which contribute importantly to incompatibility and functional failure of implant materials are examined. The interaction of these criteria in the etiology of implant failure is discussed in terms of the host response to an inert implant and the modulation of this response in the presence of cytotoxic sequellae. Cellular injury either of traumatic or biochemical origin is seen to stimulate sequestration of the offending implant by fibrous tissue. Difficulties associated with routine quantification of such response by animal implantation studies have led to development of rapid in vitro techniques to predict the quantity and cytotoxicity of moeities released by an implant. These techniques are based on infrared analysis and primary mammalian tissue culture with a pseudo body fluid to which materials are exposed at elevated temperature. The protocols allow formulation of rational criteria for rejection of candidate materials for clinical implantation and acceptance for definitive preclinical animal implant studies. The procedures are applicable for routine monitoring of materials accepted for fabrication of prototype or production implants and of fabricated prostheses.
An evaluation of polyelectrolyte complexes as biomedical materials
Authors: Marshall David W. , Cross Robert A. , Bixler Harris J. 
Published: December 2004

AbstractCertain polyelectrolyte complexes have been developed which appear to be nonirritating to body tissues and do not initiate thrombus when in contact with the bloodstream.In vivotest results with animals are discussed salong with a description of the physical and chemical properties of the material. Methods of improving the mechanical properties of the complexes have been developed and illustrations of several simple biomedical devices are shown.
Surface microstructural factors and the blood compatibility of a silicone rubber
Authors: Nyilas E. , Kupski E. L. , Burnett P. , Haag R. M. 
Published: December 2004

AbstractAfter early failures, a series of injection molded Silastic 372 (Medical Grade) Auxiliary Ventricle surfaces became implantable, under identical hemodynamic conditions, for 3–4 weeks with no formation of adherent thrombi. Improvement in blood compatibility is attributed to a preparative technology devised to eliminate various impurities and surface inhomogeneities found by physico‐chemical and electron microscopic techniques in Silastics which thrombosed rapidly in vivo. These imperfections were traceable to processing methods and/or resulted from properties inherent to the uncured elastomer. In addition to traces of molding cavity exudates, 2,4‐dichlorobenzoic acid, a decomposition product of the Silastic's peroxide catalyst can contaminate finished elastomers in amounts varying according to curing conditions. Sodium stearate solutions used to remove impurities were found to deposit microlayers which became irreversibly adsorbed as a result of transformation into stearic acid insoluble in neutral aqueous media. Aided by the lack of strong bonding between the filler and some of the Silastic's poly‐(dimethylsiloxane), certain molding conditions can expose silica particles in submicroscopical domains inducing clots. Demonstrated by electron micrographs and transmission sections, processing technology was found to affect the submicroscopic structure which can alter the compatibility of otherwise identical Silastics within wide ranges. These factors are recognized as important determinants of compatibility.
An evaluation of inert and resorbale ceramics for future clinical orthopedic applications
Authors: Hentrich R. L. , Graves G. A. , Stein H. G. , Bajpai P. K. 
Published: December 2004

AbstractThe compatibility of implanted ceramic materials with autogenous bone, and the subsequently noted influence of the ceramic on the rate of new bone formation, were investigated to evaluate such materials for use in orthopedic implants. Three ceramic materials, aluminium oxide (Al2O3), zirconium oxide (ZrO2), and calcium aluminate (yCaO · xAl2O3) were tested. These were placed in the femurs of rhesus monkeys for periods of 50, 100, and 350 days. Definite compatability between the autogenous bone and the materials was exhibited for the implant time periods evaluated. No toxicogenic activity was noted in any of the biochemical, biomedical, and ceramographic evolutions. An added benefit resulted from the calcium aluminate composition, which was fabricated as a two‐phase oxide material to make it slightly soluble in the body fluids. In the 50‐ and 100‐ day implants, the bone penetrated the ceramic for distances up to 100 μ while the ceramic dissolved and the pores enlarged. In addition, the mineralization in the area of the calcium aluminate was greater than that found around the other ceramics. Radiographs over the entire 350‐day implant period confirmed the increased callus formation around all of the materials with no signs of rejection evident in the surrounding osseous or soft tissues. After 350 days the entire pore area of the calcium aluminate ceramic was infiltrated with a columnar substance which on the basis of scanning electron microscope procedures was considered to be mineralized osteoid.
Lytic effects of plastic surfaces on erythrocytes
Authors: Dyck M. F. , Winters P. R. 
Published: December 2004

AbstractTwenty‐one commercial plastics were exposed to 10% red blood cell suspension in buffered saline and their hemolytic effect was determined. The depression in surface tension of physiological saline solution exposed to the plastic surfaces was recorded and brought into relationship with their hemolytic behavior. It has been shown that both effects occur simultaneously. It is proposed to use the depression in surface tension of saline exposed to prospective plastic applicants as a bloodcindependent screening test for evaluation of plastics which are intended to be exposed to a cardiovascular environment.
Tolerance of modified poly(glycol methacrylates) by the organism
Authors: Barvič M. , Vacík J. , Lím D. , Zavadil M. 
Published: December 2004

AbstractInvestigation has been made of the short‐term tolerance of hydrophilic polymers on the basis of poly(hydroxy ethyl methacrylates) containing various amounts of acidic and basic groups. The worst tolerance was found with gels containing basic groups alone.
A device to study the degradation of blood in a shear field with controlled wall effects
Authors: Whiffen J. D. , Lightfoot E. N. , Dennis W. H. , Safford R. E. , Powaser M. M. , Solen K. A. 
Published: December 2004

AbstractA technique is described for studying shear‐induced degradation of blood with near‐uniform shear exposure to walls of a single material. The device used is a specially designed coni‐cylindrical viscometer with essentially all blood‐contacting surfaces constructed of a single test material. The technique developed permits exposure of blood only to this material under such conditions that significant shear occurs only in the viscometric region of the device. Contact with air is prevented. Preliminary data are reported for blood taken from fasting dogs and tested in a prototype device constructed of polycarbonate (Lexan). Venous blood was found to hemolyze much more than arterial blood and the extent of hemotysis increased with time. Changes were also observed in the electrophoretic pattern of the plasma proteins.
Radiopaque denture base materials technic dentures
Authors: Chandler H. H. , Bowen R. L. , Paffenbarger G. C. 
Published: December 2004

AbstractTechnic dentures were made using composite base materials containing 30,40, and 50 weight % of a silance‐treated, readiopaque, powdered glass as the reinforcing filler and poly (methyl methacrylate) as the matrix. Dentures containing no glass were included for comparison. Molar‐to‐molar dimensional changes, effects of silance treatment fo the procelain teeth and handling and finishing characteristics were determined.Dentures containing glass had less dimensional change during curing and subsequent water storage than those without glass. Thick upper dentrues exhibited the least change and thin lowers, the most. The Differences in the magnitudes of the changes would not be clinically noticeable.Silance treatment fo the procelain teeth in thick upper dentures resulted in breakage of theposterior teeth in almost all instances. posterior teeth also freactured in thick upper dentures containing 40 and 50% of the silance‐treated glass even though the teeth were not treatedwith silance.Mixing and molding properties of the composite materials, while acceptabgle, were slightly inferior to thematerial containing ono glass. Finiching characteristics were definitelyinferior in that it was more difficult and time‐consuming to attain the fial surfaces and these surfaces were not as smooth as smooth as those in dentures without glass.
Resorbable ceramic implants
Authors: Graves G. A. , Hentrich R. L. , Stein H. G. , Bajpai P. K. 
Published: December 2004

AbstractThe purpose of the investigation was to show the ability of two calcium aluminate ceramic compositions to act as suitable implants for partial replacements of long bones. It was anticipated from previous studies that the ceramic would be well tolerated by the autogenous bone and surrounding soft tissue while the ceramic was slowly dissolving in the body fluids, allowing new osseous tissue to penetrate the resulting pore structure. It was expected that after a period of time the ceramic would no longer exist as a separate entity but would be completely infiltrated with mineralized osseous tissue and ultimately be completely replaced by bone. Two ceramic implants were prepared by slightly different techniques and CaO to Al2O3 ratios. The result was a polyphase ceramic and a nearly single phase ceramic. The polyphase material, after implantation in the test subject for 32 weeks, was completely impregnated with connective tissue while undergoing considerable alteration in microstructure. The single‐phase material was not altered significantly in any way. This implant could not be fully evaluated for its ability to allow for osseous tissue formation on its surface, or within its open pore structure, due to slight variations in the original fixation of the implant and resulting attempts to correct the problems.
Dental cements, direct filling resins, composite and adhesive restorative materials: A resume
Authors: Paffenbarger George C. 
Published: December 2004

AbstractThis resume concerns experimental and commercial dental cements and restorative and adhesive materials usually containing nonmetallic inorganic components, the biocompatibility of the above with oral tissues, proposed methods of bioevaluation, the oral environment, the nature of the hard tooth tissue, cavity treatment, agents for bonding the restorative material to the tooth, and 112 references.The cements include those based on (C‐1) zinc oxide‐eugenol with additives such as zinc acetate, rosin, polymers and most important o‐ethoxybenzoic acid (EBA); (C‐2) metallic oxides‐phosphoric acid; (C‐3) acid phosphate salts‐water; (C‐4) aluminosilicate glass‐phosphoric acid; (C‐5) zinc oxide‐polyacrylic acid; (C‐6) methyl methacrylate‐poly‐(methyl methacrylate) with or without inorganic fillers. Direct filling resins (C‐6) without filler and composite restorative materials (C‐6) with filler are based on acrylic resins or reaction products of acrylic (methacrylates) with other resins. Coupling agents include cyanoacrylates, epoxy‐acrylic adducts and polyurethanes. The 10 tables give composition, values for pertinent physical properties or dental requirements. (C‐2) Dominates the cements but (C‐1) with (EBA) and (C‐5) which has some adhesion to hard tooth tissues and stainless steel may displace (C‐2). (C‐4) Restorative materials are anticariogenic and widely used but are being supplanted by composite restorative materials.
Macromolecular aspects of biocompatible materials—a review
Authors: Bruck Stephen D. 
Published: December 2004

AbstractThis paper is limited chiefly to the question of blood compatibility and will not cover areas such as dental applications and mechanical support prostheses. The demand for blood compatible materials has become important for cardiac and pulmonary assist devices and artificial hearts. Since the second World War, a larger number of synthetic materials became available ranging from elastomeric to hard, hydrophobic to hydrophilic systems, but almost all of these were developed for large‐scale commercial end‐use where the presence of small quantities of impurities, traces of catalysts, plasticizers, etc., is not too critical. For medical implants, it is necessary to prepare the appropriate polymers in the chemically pure state. The ultimate goal is the fabrication of practical, economical, and working devices. This goal demands that the material not only be compatible with blood, but also be able to perform distinct mechanical and physico‐chemical functions or be useful for the isolation of implantable prostheses from body fluids.
Development of blood‐compatible elastomers. III. Hematologic effects of avcothane intra‐aortic balloon pumps in cardiac patients
Authors: Nyilas E. , Leinbach R. C. , Caulfield J. B. , Buckley M. J. , Austen W. G. 
Published: December 2004

AbstractAs of this date, tri‐segmented intra‐aortic balloons made from Avcothane‐51 elastomer were applied in the counterpulsation treatment of about 80 cardiac patients. The combined effects induced by the implanted elastomer and the hemodynamics of pumping are analyzed by means of hematologic changes observed in a set of 28 patients who were treated at the Massachusetts General Hospital for an average period of about 4 days, and represent a widely diversified group in terms of their clinical conditions. In no case were, any significant adverse hematologic effects induced by this assist device whether the hosts had been anticoagulated or not heparinized at all. While platelet levels were somewhat affected by the assist device, the particular conditions of the patient appear to have an effect of at least, equal magnitude. In addition to platelet levels steadily decreasing with pumping time, changes in platelet levels similar to the pattern of “platelet tide” occurred with about equal frequency. Monitored in terms of erythrocyte counts and plasma hemoglobin levels, no significant degree of hemolysis could be detected. Leukocyte counts in patients having above‐normal levels at the beginning of pumping returned to normal while in other cases there were no significant changes. Fibrinogen, one of the plasma proteins most sensitive to foreign surfaces, showed levels increasing from subnormal to normal as a function of pumping time. The overall in vivo performance of Avcothane‐51 balloons appers to be consistent with the state of the surfaces of recovered devices, showing only the presence of occasional adherent platelets upon examination by scanning electron microscopy.
Vitreous carbon percutaneous elctrodes for muscle stimulation
Authors: Gibbons D. F. , Peckham P. H. , Martin R. L. 
Published: December 2004

AbstractIn vivo and in vitro tests have demonstrated that vitreous carbon anodes are corroded when operated under conditions typical of those used for the physiological stimulation of muscle. Similar electrodes are completely inert under cathodic conditions. The chronic stimulation experiments demonstrate acute and chronic inflammation with increased vascularity in the tissue adjacent to an anode.
Artificial skin I. Preparation and properties of pluronic F‐127 gels for treatment of burns
Authors: Schmolka Irving R. 
Published: December 2004

AbstractThe preparation of block polymer surface‐active agents derived solely from propylene oxide and ethylene oxide is described. The physical properties of a nonionic surfactant of 12,500 molecular weight, Pluronic F‐127, are presented. The toxicity data of the polymeric series is reviewed. The preparation of cold aqueous solutions of the F‐127 solution, to which silver salts and other medicaments are then added, is described. By raising the temperature, these fluid liquids are then converted to strong “ringing” gels or viscous ointments which are suitable for application to a burn wound or abraded skin area. The factors involved in altering the yield strength of the gel are presented.
Carbon fiber reinforced polyethylene for possible orthopedic uses
Authors: Sclippa Ermes , Piekarski K. 
Published: December 2004

AbstractProperties of injection‐molded high‐density polyethylene reinforced with carbon fibers were investgiated. With 20% by weight carbon fibers tensile strength of polyethylene was almost doubled. Further increase of volume fraction of fibers did not produce as dramatic results. With 40% by weight carbon fibers, elastic modulus increased one order of magnitude: from 0.225 × 106 psi to 2.48 × 106 psi. This value is close to the value of the elastic modulus of bone, hence the material may substitute for bone where the same stiffness is required. The total strain at fracture was reduced two orders of magnitude, but still stayed comparable to total strain at in bone failures (1–2%).No appreciable changes were noted in shear strength, impact strength and wear resistance. The work to fracture increased from 0.9 to 2.9 kg cm/cm2 with 40% of carbon fibers.The most significant improvement of polyethylene with addition of carbon fibers was demonstrated in measurements of viscoelastic properties of the material. Creep characteristics were dramatically improved.In summary, it can be stated that injection‐molded reinforced polyethylene has much superior properties to the nonreinforced P.E. which can be further improved if better adhesion between P.E. matrix and reinforcing fibers can be secured.
New types of synthetic infusion solutions. I. Investigation of the effect of solutions of some hydrophilic polymers on blood
Authors: Kopeček J. , Šprincl L. , Lím D. 
Published: December 2004

AbstractThe behavior of aqueous solutions of poly [N‐(2‐hydroxypropyl) methacrylamide], poly(N‐ethyl methacrylamide), poly(N‐ethyl acrylamide), and poly‐(triethyleneglycol monomethacrylate) was investigated and characterized in tests required for synthetic infusion solutions. The above solutions were characterized from the viewpoint of toxicity, pyrogenic properties, antigenic properties, effect on the determination of the blood groups, and effects on hemocoagulation. The elimination from blood circulation was studied on several fractions of the 14C‐labelled poly[N‐(2‐hydroxypropyl) methacrylamide] having different molecular weights. It was found that in all tests the properties of the polymers investigated do not depart from the expected behavior.
Development of block copolyether‐urethane intra‐aortic balloons and other medical devices
Authors: Brash John L. , Fritzinger Bruce K. , Bruck Stephen D. 
Published: December 2004

AbstractThe development of materials and technology suitable for the fabrication of intra‐aortic balloons (IABs) is described; a brief discussion of materials and a fabrication process for flexible ventricular assist devices (heart massage cups) is also given. A series of block copolyether‐urethanes was developed, the mechanical properties of which can be varied over a wide range. One member of the series was “tailored” specifically for nondistensible IABs of a particular design. Several of the block copolyether‐urethanes were subjected to selected in vitro and in vivo tests for blood compatibility and compared favorably with other materials. A two‐stage process was developed for the fabrication of high‐quality IABs from block copolyether‐urethanes. This process involves dip‐forming over expendable wax mandrels, followed by removal of the wax and solvent‐welding the balloon to the tip and catheter.
Aspects of three types of hydrogels for biomedical applications
Authors: Bruck Stephen D. 
Published: December 2004

AbstractSome of the chemical and physical properties of three different hydrogels are analyzed as they relate to biological compatibility. The importance of the permeability and diffusion coefficients, porosity, and the possible role of quasiorganized water within the hydrogels are emphasized. It is suggested that the biological environment with its dissolved components such as ions, proteins, carbohydrates, lipids, and enzymes will influence the ultimate biological performance of hydrogels. This biological performance will depend not only on the hydrophilicity of the system but on numerous other parameters including the chemical composition, types and number of crosslinks, presence of functional groups, quasi‐organized water structure, porosity, and the thermodynamic interaction parameters between the components of the biological environment and the gel. It is suggested that the presence of anionic gorups on certain synthetic hydrogel surfaces may be not essential for blood compatibility, provided that such materials are carefully distinguished from other hydrophilic gels.
Analyses of a silicone elastomer heart ball valve
Authors: Mayhan K. G. , Biolsi M. E. , Simmons E. M. , Almond C. H. 
Published: December 2004

AbstractThis work represents a preliminary study of one case history of a silicone heart valve. The laboratory techniques employed have proven useful in characterizing the polymer before and after implantation. Before any model explaining ball variance can be proposed it must be determined whether the polymer loses its integrity because specific constituents in the body fluids interact with primary valence bonds in the polymer chains, or if the fluids simply cause swelling and plasticization of the crosslinked system and the damage is the result of mechanical work on the weaker polymer system. Detailed kinetic and thermodynamic studies are underway to answer these questions.The work summarized in this paper refers to the evaluation of only one specimen and should not be taken to mean that every silicone ball from a heart valve prosthesis will show this variance. The incidence of functionally variant silicone balls as reported to one manufacturer represents approximately 1.5% of the aortic and less than 0.05% of the mitral prostheses which have been supplied by this manufacturer. A small percent of valves of this type have the potential of becoming functionally variant and this is one failure mode which should be considered in the implantation of silicone ball valves.