bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical behavor of aluminum in human plasma
Authors: Salvarezza R. C. , de Mele M. F. L. , Videla H. H. , Goñi F. R. 
Published: December 2004

AbstractThe electrochemical behavior of aluminum in isotonic saline solutions, citrated human plasma, and citrated human blood is studied using potentiostatic and potentiodynamic polarization techniques complemented with scanning electron microscopy (SEM) and dispersive x‐ray analysis. The effect of corrosion products on plasmatic proteins is investigated using electron microprobe analysis and immunoelectrophoresis analysis. Electrochemical data show a breakdown of the protective film on aluminium, due to the action of chloride, leading to the pitting of the metal. During pitting, the interaction of aluminium ion and the plasma proteins produces a nonadherent precipitate. Strong protein denaturation can be observed by immunoelectrophoresis of the precipitate suspended in physiologic solutions. The convenience of using organic fluids in addition to saline solutions to evaluate in vitro the behavior of metal for implants is suggested.
Glucose‐sensitive membranes containing glucose oxidase: Activity, swelling, and permeability studies
Authors: Kost Joseph , Horbett Thomas A. , Ratner Buddy D. , Singh Manindar 
Published: December 2004

AbstractThe development of membranes that swell in response to glucose is reported. The membranes may prove to be useful in glucose monitoring or glucose‐dependent insulin delivery. The polymers were synthesized by the radiation‐induced polymerization of frozen solutions containing hydroxyethyl methacrylate, N,N‐dimethylaminoethyl methacrylate, tetraethylene glycol dimethacrylate, ethylene glycol, water, and glucose oxidase. The polymers were hydrogels, with water contents in the range of 60–90%, depending on the pH or glucose concentration. Changes in swelling and permeability of the hydrogel were caused by exposure to glucose solutions. The gluconic acid formed by the glucose oxidase catalyzed oxidation of glucose in the membrane lowered the pH of the system and thus caused the changes in the membrane. The retention of enzyme activity by the membranes in vitro and in vivo is also reported. The large differences in properties among membranes made with different chemical formulations suggest that glucose‐sensitive membranes with performance characteristics needed for an artificial pancreas may be an achievable goal.
Percutaneous healing of clinical tympanic membrane implants
Authors: Powers Dennis L. , Henricks M. Lucile , Von Recum Andreas F. 
Published: December 2004

AbstractPercutaneous healing is plagued by materials compatibility problems, epidermal reactions, and mechanical factors. To our knowledge, no studies have evaluated the effects of one of these factors while controlling the others. The tympanic membrane is an implant site where mechanical factors are minimized. Titanium has been shown to be a very histocompatible material, although no reports of the histology of percutaneous titanium implants exist. This study reports on aspects of the epidermal and connective tissue healing around titanium tympanic membrane implants that were explanted from human subjects. The lack of inflammation and the direct adherence of the tissues substantiate the materials compatibility and the absence of mechanical factors. Tissue healing patterns appear to reach an equilibrium which is suitable for the long‐term exixtence of the percutaneous device. This implant location provides a suitable model for studying the tissue reactions to various percutaneous materials.
Lysis time and FDP immunoprecipitation by soluble and immobilized urokinase
Authors: Senatore Fred , Bernath Fred 
Published: December 2004

AbstractUrokinase (UK) was immobilized to the lumen of dacron‐reinforced fibrocollagenous tubes (UK‐FCT) using a glutaraldehyde entrapment process, in an effort to develop a fibrinolytic small diameter (i.e., 4 mm i.d.) vascular graft. Soluble and immobilized urokinase were evaluated for their ability to lyse synthetic clots made from purified physiologic substrates, α2 plasmin inhibitor (α2PI) mediated whole canine blood (WCB) and α2PI‐depleted WCB by measuring lysis time and fibrin degradation product (FDP) formation. Lysis times were orders of magnitude lower and FDP formation rates were orders of magnitude higher with synthetic clots compared with either α2‐mediated or α2‐depleted WCB clots as a substrate, using both soluble and immobilized UK. However, both soluble and immobilized UK catalyzed FDP formation at an enhanced rate for α2PI‐depleted WCB compared with the inhibitor‐mediated substrate. These results suggest that both soluble and immobilized UK behave similarly when treated with either standard clots, α2PI‐mediated WCB and α2PI‐depleted WCB as substrates and the use of urokinase‐bound fibrocollagenous tube may prove suitable as a fibrinolytic vascular prosthesis.
Release of corrosion products by F‐75 cobalt base alloy in the rat. II: Morbidity apparently associated with chromium releasein vivo: A 120‐day rat study
Authors: Wapner K. L. , Morris D. M. , Black J. 
Published: December 2004

AbstractThere is concern whetherin vivocorrosion of chromium–cobalt alloys releases ions containing trivalent [Cr(III)] or hexavalent [Cr(VI)] chromium. The question arises from indications that Cr(VI) is far more biologically active than Cr(III). Using a previously developed microsphere implant model, specimens of F‐75 chromium‐cobalt‐molybdenum alloy were implanted in rats for periods up to 120 days. Blood and urine were collected at intervals during the study. Significant postoperative serum and urine chromium concentration elevations were observed. In addition, weight gain inhibition, lung morbidity, and animal mortality, related to the implant surface area to animal body weight ratio (SA/BW), were observed. Comparison of measured chromium serum concentrations with those concentrations found by others to be biologically active in tissue culture studies strongly suggests the release of Cr(VI) in this study.
Glass transition temperatures of dental porcelains at high heating rates
Authors: Twiggs S. W. , Hashinger D. T. , Morena R. , Fairhurst C. W. 
Published: December 2004

AbstractThe glass transition temperature (Tg) of a dental porcelain is a factor in determining the magnitude of residual stresses introduced in a dental porcelain during cooling of a porcelain‐fused‐to‐metal prosthesis. Tg is known to vary with changes in heating or cooling rate. However, available commercial instrumentation does not permit Tg to be obtained at the very high cooling rates commensurate with actual dental laboratory practice. Tg values are reported here for a number of commercial dental porcelains and other materials. These data were obtained by the bending beam technique, employing a special low thermal‐mass furnace to permit rapid heating and cooling rates. Measurements were made at rates as high as 600°C/min. Coefficients of determination (r2) for 1/Tg vs. In (heating rate) were excellent. This relation is consistent with previously reported low rate Tg data obtained by a different technique.
Evaluation of anti‐inflammatory agents using a model of granuloma formation evoked by divinyl copolymer beads in the mouse lung
Authors: Coleman Sylvia E. , Hood C. Ian , Schoen Frederick J. , Rheinhardt Jeanette M. 
Published: December 2004

AbstractWe have developed and quantitated a reproducible standardized granulomatous inflammatory reaction using divinyl copolymer beads. Approximately 10000 gas sterilized beads (43–53 μm in diameter) are injected into the tail veins of mice and embolize to the lungs where they evoke granuloma formation which is maximal at 48 h. The anti‐inflammatory effects of both steroidal and nonsteroidal agents, namely, bacterial levan, hydrocortisone acetate, polyanetholsulfonate, indomethacin, acetylsalicylic acid, ellagic acid, and aminophylline were determined by comparing granuloma size in treated animals with those in untreated controls. Granulomas in paraffin sections were traced on the ground glass screen of a light microscope and the area of each granuloma measured with a digitizer‐computer programmed to prepare histograms and merge data from replicate experiments. Of the agents tested, the greatest reductions in granuloma size occurred after treatment with bacterial levan (71%), hydrocorticone (70%), polyanetholsulfonate (58%), and indomethacin (55%).
Mechanical effects on rates of hemolysis
Authors: Nakahara Toro , Yoshida Fumitake 
Published: December 2004

AbstractEmpirical studies were conducted on how rates of hemolysis were influenced by mechanical factors, such as shear, turbulence, agitation, pressure fluctuation, and bubbling, in five types of experimental apparatus: rotating cylinder, rotating disks, agitated vessel, pressure pulsator, and bubble columns. Our data indicate, at least qualitatively, that an important mechanical factor controlling rates of hemolysis in practical devices, in which blood does not flow in thin channels or capillaries, is the turbulent stress in the bulk blood, rather than the shear at the blood–solid interface.
Bacterial inhibition by electrical activation of percutaneous silver implants
Authors: Spadaro J. A. , Chase S. E. , Webster D. A. 
Published: December 2004

AbstractPercutaneous silver wire implants were looped through the dorsal skin of rats and inoculated with Staphylococcus aureus to test the effect on bacteria in the tract. The silver was activated with four brief daily applications of anodic microcurrent. Contralateral 316L stainless steel implants, identically inoculated, served as controls. Cultures from the silver tracts showed a marked reduction or elimination of bacteria, which persisted for the 3‐week study period. In tracts with colonization established for 1 week, subsequent electrical activation of the silver also suppressed the bacteria. Inflammatory reactions at 3 weeks were mild at both the silver and stainless implants and no giant cells or toxicity were seen. This suggests that electrically activated silver may be useful in preventing or treating infection at percutaneous devices.
Perforated demineralized bone matrix: A new form of osteoinductive biomaterial
Authors: Gendler E. 
Published: December 2004

AbstractThis study was undertaken to evaluate a new osteoinductive material—perforated decalcified bone matrix (PDBM). Subcutaneous implantation of PDBM induces multiple centers of endochondral osteogenesis with subsequent resorption of bone matrix and its replacement by new bone. PDBM should therefore prove useful as a research model to study osteoinduction and in the clinical situation in orthopedic and reconstructive surgery for the filling of bone defects and stimulation of fracture healing.
The kinetics of baboon fibrinogen adsorption to polymers: In vitro and in vivo studies
Authors: Horbett T. A. , Cheng C. M. , Ratner B. D. , Hoffman A. S. , Hanson S. R. 
Published: December 2004

AbstractFibrinogen adsorption on polymers from blood may mediate or potentiate thrombosis because of its involvement in both the intrinsic clotting system and the formation of platelet aggregates. While the kinetics of fibrinogen adsorption from plasma in vitro have previously been found to be very different on polar and nonpolar surfaces [T. A Horbett, “The kinetics of adsorption of plasma proteins to a series of hydrophilic‐hydrophobic copolymers,” ACS Org. Coat. Plas. Chem., 40, 642–646 (1979)] the significance of this difference with respect to thrombogenesis in vivo has not been clarified. In this study, the kinetics of deposition of baboon 125I fibrinogen from plasma in vitro or from blood in vivo on a series of polymers was measured. The polymers chosen for this study had previously been found to have a large range in surface polarity and reactivity in the in vivo baboon shunt model. The kinetics of fibrinogen adsorption in vitro were observed to be of three types, depending on the polymer: (1) high initial adsorption decreasing to a lower steady state value; (2) constant throughout the time course; (3) low initial adsorption rising steadily to a plateau value. In vivo, fibrinogen deposition kinetics were of two types: (1) low, constant deposition throughout the time course, independent of heparinization; (2) low deposition initially followed by a second phase of greatly increased deposition (probably as fibrin) which was prevented or greatly decreased by heparinizing the animals. Polymers for which fibrinogen adsorption increased to a plateau in vitro were found to have a heparin inhibitable second phase of enhanced in vivo fibrinogen deposition. These polymers also have been found in previous studies to enhance the rate of platelet destruction when used as in vivo shunts on baboons. Conversely, most polymers with high initial in vitro fibrinogen adsorption followed by a decrease had low fibrinogen deposition behavior in vivo and were also minimally destructive of platelets. The adsorption kinetics of fibrinogen to polymers from blood in vivo and in vitro and the consumption of platelets in vivo induced by the polymers all vary with polymer polarity. More polar polymers had in vitro fibrinogen kinetics characterized by a rise to a plateau, in vivo fibrinogen deposition characterized by a second stage of great increase inhibitable by heparin, and enhanced platelet consumption. The correlation of three separate indicators of surface thrombogenicity with surface polarity suggests that more polar materials may be more thrombogenic because of an influence on the way in which fibrinogen interacts with these surfaces.
Mechanical characterization of commercially made carbon‐fiber‐reinforced polymethylmethacrylate
Authors: Saha S. , Pal S. 
Published: December 2004

AbstractAcrylic bone cement is significantly weaker and of lower modulus of elasticity than compact bone. It is also weaker in tension than in compression. This limits its use in orthopedics to areas where tensile stresses are minimum. Many authors have shown that addition of small percentages of fiber reinforcement by hand mixing improved the mechanical properties significantly but with variable results. In this investigation we have examined the mechanical properties of machine‐mixed, commercially available carbon‐fiber‐reinforced bone cement. Appropriate samples of normal low‐viscosity cement and carbon‐fiber‐reinforced cement were prepared and tested mechanically. Carbon fiber increased the tensile strength and modulus by 30% and 35.8% respectively. The compression strength and modulus, however, increased by only 10.7%. Similarly, bending and shear strengths improved by 29.5% and 18.5%, respectively. Diametral compression strength, which is an indirect measure of tensile strength, however, showed only 6.2% improvement. The maximum temperature rise during polymerization was also reduced significantly by the fiber reinforcement.
Effect of pore size of porous bead carriers immobilizing antibody on IgE adsorption
Authors: Sato Hiroshi , Kidaka Teruhisa , Hori Masatake 
Published: December 2004

AbstractImmunoglobulin E (IgE) adsorption was studied using antihuman IgE antibody immobilized on alkylamine glass carriers with different pore sizes (Controlled Pore Glass [CPG]®) to determine the effect of pore size on IgE adsorption in therapeutic immuno‐adsorbents. With a series of CPGs whose pore sizes were in the range of 170 to 1400 Å, CPGs possessing pore sizes larger than 500 Å had higher IgE adsorption. A CPG (500‐Å pore size) with the spacer arm 20 Å long did not give better IgE removal than CPG without the spacer arm, since the spacer prevented the immobilization of a sufficient amount of the antibody on the carrier because of steric hindrance. However, the antibodies, once immobilized on CPG with the spacer arm, bound the same amount of IgE molecules (antigens) as those immobilized on CPG without the spacer arm.
Crystallinity and solubility behavior of iron‐containing fluoridated hydroxyapatites
Authors: Okazaki Masayuki , Takahashi Junzo , Kimura Hiroshi 
Published: December 2004

AbstractIron‐containing fluoridated hydroxyapatites with various fluoride contents were synthesized at 80°C and pH 7.4 using FeCl2 · nH2O as a source of iron. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a‐Axis dimensions of Fe‐containing apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. All Fe‐containing fluoridated apatites were less well crystallized than Fe‐free fluoridated apatites previously reported, although with increasing degree of fluoridation, the crystallinity behavior of the former apatites appeared analogous to that of the latter apatites. In contrast to this inhibited crystallinity behavior, the apparent solubility of Fe‐containing fluoridated apatites decreased more than that of Fe‐free fluoridated apatites at low fluoride content.
Antithrombogenic heparinized polyacrylonitrile copolymer
Authors: Miyama Hajime , Fujii Nobuyuki , Kuwano Atsushi , Nagaoka Syoji , Mori Yuichi , Noishiki Yasuharu 
Published: December 2004

AbstractA new antithrombogenic polymer was synthesized by the photograft‐copolymerization of methoxypolyethyleneglycol methacrylate and dimethylaminoethyl methacrylate to polyacrylonitrile containing bromine atoms, and by quaternizing and heparinizing the graft‐copolymer.Hydrophilicity and heparin content of the polymer could be controlled by changing the feed ratio of the acrylates to be grafted. The heparinized polymer showed excellent mechanical and antithrombogenic properties.
The biological performance of calcium phosphate ceramics in an infected implantation site: II. Biological evaluation of hydroxyapatite during short‐term infection
Authors: Van Blitterswijk C. A. , Bakker D. , Grote J. J. , Daems W. Th. 
Published: December 2004

AbstractMacroporous hydroxyapatite was implanted submucosally in the rat middle ear and studied after intratympanic injection of a Staphylococcus aureus suspension. The middle ear infection was induced 1 week after the implantation, and the effects of infection on the middle ear and the implant material were evaluated after 1, 3, 7, and 14 days by light and electron microscopy. The findings in the infected middle ear with an implant corresponded well with those described for the infected middle ear cavity without an implant. The reactions of the tissue over the implant were similar to those of the original mucosa of the middle ear.Bone was deposited on the implant and in its pores in relatively large quantities. Biodegradation, due at least partially to phagocytic activity of macrophages and multinucleated cells, was more prominent than previously found. This higher degree of biodegradation may be attributed to the use of the mucosal implantation technique, because this was the only point of divergence with respect to material or methods from earlier work reported by our group.The present results, together with those published earlier, suggest that this material has promising features for use as a bone substitute in reconstructive middle ear surgery. Definitive conclusions on biological performance and biofunctionality will, however, have to await long term clinical trials.
Adsorption of plasma proteins to the derivatives of polyetherurethaneurea carrying tertiary amino groups in the side chains
Authors: Ito Yoshihiro , Sisido Masahiko , Imanishi Yukio 
Published: December 2004

AbstractPolyetherurethaneureas carrying tertiary amino groups in the side chains were synthesized, quaternized, and heparinized. The adsorption of plasma proteins to the polyurethane derivatives was investigated using Fourier‐transform infrared, surface fluorescence, ultraviolet, and circular dichroism spectroscopy. Bovine γ‐globulin and bovine plasma fibrinogen were easily adsorbed to hydrophobic polyurethanes and denatured. It was found that the β structure was generated during the irreversible conformational change of the proteins on adsorption to hydrophobic polyurethane materials. On the other hand, bovine serum albumin was easily adsorbed to hydrophilic quaternized and heparinized polyurethanes without a serious conformational change. The conclusion was drawn that a polymer material that selectively adsorbs bovine serum albumin in a native state could be antithrombogenic.
Identification of proteins adsorbed from human plasma to glass bead columns: Plasmin‐induced degradation of adsorbed fibrinogen
Authors: Brash J. L. , Thibodeau J. A. 
Published: December 2004

AbstractIn a bead column experiment, attempts have been made to identify the proteins adsorbed from plasma onto a glass surface. Proteins adsorbed after a 3‐h contact time were eluted sequentially by 1 M tris buffer and SDS. Polyacrylamide gel electrophoresis of eluted proteins showed a multiplicity of components, and not all of these could be identified. Positive identifications were made by immunodiffusion against specific antibodies, band positions on electrophoresis gels, and location of radioactivity in gels when specific radiolabeled proteins were added to plasma. Proteins found were albumin, IgG, fibrinogen, plasminogen, and fibrinogen degradation products (FDP). A major component with an apparent molecular weight of 25,000 remains unidentified. It is unrelated to albumin, IgG, fibrinogen, factor XII, or plasminogen. Adsorbed fibrinogen was less degraded when experiments were performed with plasmas deficient in either plasminogen or factor XII. It is therefore concluded that FDP are formed by activation of adsorbed plasminogen, as was found previously for purified fibrinogen containing a trace of plasminogen.11 At least part of this activation is potentiated by the contact activation phase of plasma coagulation, in particular activated factor XII.
Influence of alloy composition on the hardening of silver–tin dental amalgam
Authors: Abbott J. R. , Miller D. R. , Netherway D. J. 
Published: December 2004

AbstractThe objective of the investigation was to examine the reactions of mercury with silver‐tin alloys with compositions spanning the phase fields β, (β + γ), γ, and (γ + Sn). The experimental methods employed include the application of light microscopy, scanning electron microscopy, and electron probe microanalysis. These techniques were used to investigate the mechanisms of reaction and to identify the nature and morphology of the reaction products formed on bulk specimens of the alloys. The progress and characteristics of the reactionsthat occur during hardening of amalgams prepared from powders of these alloys were monitored using a highsensitivity dilatometer. These results were correlated with direct observations on the development of the microstructures. The reaction of mercury with the β‐phase alloy occurred rapidly and resulted in a very marked and rapid expansion during the initial stages of hardening. γ‐Phase alloys, on the other hand, reacted more slowly and contracted markedly during hardening. The behavior of amalgams made from alloys with compositions lying between these two extremes appeared to be explicable in terms of the characteristics of the separate phases from which they were constituted.