bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption of proteins onto hydrophobic polymer surfaces: Adsorption isotherms and kinetics
Authors: Lee Randy G. , Kim Sung Wan 
Published: December 2004

AbstractAdsorption of albumin, γ‐globulin, and fibrinogen from solution, under both static and flow conditions, onto several hydrophobic polymers was studied using internal reflection infrared spectroscopy. Isotherm curves experimentally found were consistant with Langmuir type adsorption. The rate and amount of protein adsorbed was found to be dependent upon both the nature of the polymer substrate and on the flow rate of the solution.
The tensile and flexural properties of bovine nasal cartilage
Authors: Flam Eric 
Published: December 2004

AbstractThe tensile and flexural behaviors of fresh bovine nasal cartilage were measured as a function of strain rate. The following conclusions may be drawn from these studies: (1) Strain rate increases the measured values of tensile and flexural stress and ultimate tensile strength. (2) The effect of strain rate is minimal under the following subultimate conditions: (a) Rates from 0.045%/sec to 2.2%/sec for tensile stress at 13.4% elongation. (b) Rates from 0.038%/sec to 0.38%/sec for flexural stress at 10% deflection. (3) The average ultimate tensile strength of bovine nasal cartilage increases from 303 psi at .045%/sec to 471 psi at 11.0%/sec, and it extends on the average to 38% before failure. (4) at 20% deflection the average value of the flexural stress is 540 psi over the strain rate of .038%/sec to 38%/sec. (5) It is important that the strain rate used in measuring the mechanical properties of biological tissues be comparable to the strain rates encountered in vivo.The values of the mechanical properties may be a function of the measurement technique. Mechanical properties are measured by exposing the material to deformation applied at a given rate. The data obtained is a function of this rate of deformation (strain rate) and therefore may not be an absolute value to be used for all stress rates. This paper presents the tensile and flexural properties of bovine nasal cartilage and the variation of these measurements with the strain rate.
Covalent immobilization of L‐asparaginase with a photochemical reagent
Authors: Yaqub M. , Guire P. 
Published: December 2004

AbstractA thermochemical–photochemical bifunctional reagent was used to immobilize asparaginase under very mild reaction conditions. Stability and specificity tests indicated that the photochemically immobilized enzyme products were unique only in their high speific catalytic activities.
Potential application of graphite fiber and methyl methacrylate resin composites as internal fixation plates
Authors: Woo S. L‐Y. , Akeson W. H. , Levenetz B. , Coutts R. D. , Matthews J. V. , Amiel D. 
Published: December 2004

AbstractThe use of conventional rigid metal plates (modulus of elasticity 30 × 106 psi) for internal fixation of difficult long bone fractures may paradoxically weaken the fractured bone through a process of osteoporosis secondary to protection of the bone from stress. The hypothesis being studied which has stimulated the present work is that a new composite plate made of less rigid material but with similar geometry to stainless steel plates may promote fracture union without the complication of osteopenia. This new composite material has a modulus of elasticity similar to that of bone (approximately 3 × 106 psi) which is more than an order of magnitude lower than that of stainless steel, yet the fracture strength of this new composite material (35,000 psi) is approximately one‐half that of stainless steel.The ability to fix diaphyseal fractures by composite plates was studied by implanting these plates in the left (experimental) radii of six dogs with transverse mid‐shaft osteotomies. The right (control) radii had similar transverse osteotomies, but were plated by conventional metal plates equal in size to the new composite plates. Four months postsurgery, all experimental and control fractures had healed.Biomechanical tests of the excised radii using a torsional loading apparatus showed there were no significant differences in strength, fracture energy, angular deformation, or maximum shearing stress when comparing the experimental to the control radii. The results are sufficiently promising to warrant additional long‐term experiments investigating this concept of internal fixation.
An in vitro test system for estimation of blood compatibility of biomaterials
Authors: Mason R. G. , Shermer R. W. , Zucker W. H. , Elston R. C. , Blackwelder W. C. 
Published: December 2004

AbstractAn in vitro test cell is described which permits exposure of artificial surfaces in sheet or film form to native human blood in the absence of a blood‐air interface. Evaluation of Cuprophane, polyethylene, Silastic, and silicone‐coated glass in the in vitro cell showed Cuprophane and silicone‐coated glass to produce the least activation of the intrinsic coagulation system, while Silastic produced the greatest degree of activation. Polyethylene gave results intermediate between those obtained with the other materials. Each of these four different materials was evaluated in the elliptical cell test system multiple times with blood from 13 different donors.Our data suggest that with the present test system and the proper experimental design, one might expect that, “on the average,” performance of 36 tests on each of two materials will be sufficient for a 10% difference in their compatibility with blood to be statistically significant at the 5% level. The number of tests is 26 for significance at the 10% level.
The effect of implantation on the physical properties of silicone rubber
Authors: Swanson J. W. , Lebeau J. E. 
Published: December 2004

AbstractMedical grade silicone rubber manufactured by Dow Corning Corporation was implanted subcutaneously in beagle dogs. At specified time intervals, the implants were removed at which time physical properties and weight changes were determined. A change in the physical properties was observed after six months implantation. Tensile strength decreased 7%, elongation 10% and the modulus at 200% extension increased 8%. After two years implantation, tensile strength had decreased 8%, elongation 15%, and 200% modulus increased 16%. After two weeks implantation, a 0.4% weight gain was seen, and after four weeks implantation the samples had gained 0.7%. However, after four weeks the weight gains stabilized and from four weeks to two years, they never exceeded 0.91%. The increase was due mainly to lipid absorption. No phospholipid or protein was detected. A chloroform/methanol extraction of the samples before implantation demonstrated 1.7% extractable silicone polymer. Samples not extracted before implantation, but extracted after implantation also demonstrated 1.7% extractable silicone polymer. This data suggests extractable silicone polymer does not leach from the medical grade silicone rubber during implantation.The data also suggests that the rubber is not being degraded to extractable silicone polymers during implantation. There were no significant differences in percent lipid up‐take or the lipid profiles between samples which had extractable silicone polymer extracted before implantation and/or those which were not extracted before implantation.It should be pointed out that the slight changes in physical properties measured in this study should not be great enough to alter the performance of the rubber in the subcutaneous environment.
The role of carbohydrate in platelet adhesion to foreign surfaces
Authors: Lee Randy G. , Kim Sung Wan 
Published: December 2004

AbstractA mechanism of platelet adhesion to foreign surfaces is proposed which involves the formation of enzyme‐substrate complex bridges between platelet glycosyl transferases and surface‐adsorbed glycoproteins. To test this hypothesis two experimental approaches were attempted. The first, in vitro, series of experiments assayed two glycosyl transferases using adsorbed plasma proteins as acceptors. Sugar‐nucleotides could be transferred onto adsorbed gamma globulin and fibrinogen but not onto adsorbed albumin. The second group of experiments quantitated platelets adhering to tubing coated with protein and subjected to treatment to remove different carbohydrate residues. Using whole unheparinized ovine blood, more platelets adhered to fibrinogen or gamma globulin coatings which had been either desialyzed or had both sialic acid and galactose removed than to the same coatings when untreated. These data, plus that of other workers, give support to the proposed mechanism.
Some effects of pore diameter on single pore bony ingression patterns in Teflon
Authors: Howe Donald F. , Svare Carl W. , Tock Richard W. 
Published: December 2004

AbstractTeflon implants containing a single cylindrical pore were surgically embedded in the femural bones of rabbits. A total of eight different pore sizes were used for each experimental animal. Their diameters ranged from 274 to 670 μm, with approximately 50 μm intervals between sizes. The amount of bone tissue ingression and its spatial distribution was assessed for each pore diameter at weekly intervals over a sixteen‐week period by bone labeling with Tetracycline injection. From these data an optimum pore diameter of between 400 to 450 μm was observed for maximum bone ingression. The distribution of new bone growth was characterized as an apposition pattern which emanated from the walls and the open end of the pore. No rejection phenomena were observed at the Teflon tissue interfaces.
Thermal conductivity studies of composite dental restorative materials
Authors: Brady A. P. , Lee Henry , Orlowski Jan A. 
Published: December 2004

AbstractThermal conductivities were determined for five commercial composite restorative materials, one composite crown and bridge cement, two cavity “bases,” and poly(methyl methacrylate). In addition, the effect on thermal conductivity of concentration and type for five resin‐reinforcing fillers was investigated. Depending upon type and concentration of filler, the composites ranged in thermal conductivity from somewhat less than that for dentin to slightly over twice that value. Because of their good marginal adaptation, the thermal conductivity of composites must either be closely matched to tooth structure or a base should be used in deep restorations.
Adsorption characteristics of cellulose acetate coated charcoals
Authors: Denti E. , Luboz M. P. , Tessore V. 
Published: December 2004

AbstractThe permeability of cellulose triacetate membrance coated activated charcoal is enhanced by treatment with KOH.The adsorption data for creatinine in aqueous solution before and after deacetylation are given. In order to study the usefulness of hemoperfusion associated with dialysis for removal of uremic toxins, some experiments were performed on the adsorption by coated and deacetylated charcoal of molecules of various molecular weights (from 113 to 40,000).Although the adsorption capacity of uncoated charcoal was better, the coated material still shows good properties in the adsorption of glucagon (mol wt 3485).The results on in vitro experiments of vitamin B12 removal by coated charcoal cartridge and CDAK Model 3 dialyzer confirms the usefulness of adsorption technique toward medium molecular weight compounds.
Amalgamation reaction on mercury‐plated dental alloy (Ag3Sn)
Authors: Okabe T. , Hochman R. F. , Sims L. O. 
Published: December 2004

AbstractThe reaction between liquid mercury and Ag3Sn was studied at room temperature using a new type of specimen; i.e. bulk Ag3Sn electroplated with mercury. The surface morphology of the specimen and the phases formed on the Ag3Sn substrate were investigated by various techniques including optical microscopy, electron (scanning) microscopy, electron microprobe analysis, and electron diffraction. It was found that the mode of formation and type of crystalline phase appearing on the Ag3Sn specimen depended on the amount of mercury available. When the amount of mercury exceeded a certain quantity (about 1 mg/cm2) only the γ1 and γ2 phases were formed. On the other hand, when the amount of mercury was reduced below a certain low value (less than 0.3 mg/cm2), another silver‐mercury phase, β1, formed as tiny “liquid‐like” drops. The experimental technique employed in the present investigation has proved to be an excellent method for studying the reaction between liquid mercury and metal specimens. This new procedure may be employed to evaluate the amalgamation ability of potential new alloy systems.
The concept of protection potential applied to the corrosion of metallic orthopedic implants
Authors: Cahoon J. R. , Bandyopadhya R. , Tennese Laura 
Published: December 2004

AbstractCyclic polarization curves obtained for a cobalt‐base casting alloy (similar to Vitallium Surgical Alloy) and for 316L stainless steel show that the cobalt‐base alloy exhibits a high (noble) protection potential whereas the stainless steel exhibits a low (active) protection potential. It is suggested that the resistance to crevice corrosion of Vitallium Surgical Alloy results from its high value of protection potential whereas the susceptibility of 316L stainless to severe crevice corrosion results from its low value of protection potential.
Residual ethylene oxide: Levels in medical grade tubing and effects on an in vitro biologic system
Authors: Mc Gunnigle R. G. , Renner J. A. , Romano S. J. , Abodeely R. A. 
Published: December 2004

AbstractThe level of residual ethylene oxide after sterilization was evaluated as a function of aeration time for three medical grade tubings. Toxicity resulting from residual ethylene oxide was determined in an in vitro tissue culture system utilizing L‐cells. The absorption and desorption of ethylene oxide from poly(vinylchloride) and polyether–polyurethane tubing were similar. In contrast, silicone tubing absorbed 85% less ethylene oxide. The time required for desorption of residual ethylene oxide was 2 hr for silicone tubing and 7 to 8 hr for poly(vinylchloride) and polyether–polyurethane tubing. Tubing samples containing 1,500 ppm or more residual ethylene oxide elicited toxic tissue culture reactions whereas samples containing 900 ppm or less showed no toxic tissue culture response.
Surface and bulk characteristics of a polyether urethane for artificial hearts
Authors: Boretos John W. , Pierce William S. , Baier Robert E. , Leroy Andre F. , Donachy Howard J. 
Published: December 2004

AbstractA segmented polyether urethane was used as the blood contacting surface in a series of 10 heart assist devices implanted in calves for periods up to 35 weeks. At termination, each was examined to correlate blood compatibility and device performance with surface properties, chemical purity, physical stability and affinity for lipid absorption.
Bone growth into porous carbon, polyethylene, and polypropylene prostheses
Authors: Cestro Herman J. , Salyer Kenneth E. , Toranto I. Richard 
Published: December 2004

AbstractUsing rats as a model, porous discs of RPG carbon and polypropylene and polyethylene were localized subperiosteally and supraperiosteally in the skull. Bone and blood vessels grew into the discs, which had adequate pore size, when placed in direct contact with bone. No bone was generated from the periosteum. Both plastic materials were estimated to be better than carbon for use in osseous reconstructive work. More long term material‐tissue stability and reaction studies should be performed.
Replamineform porous biomaterials for hard tissue implant applications
Authors: White Eugene W. , Weber Jon N. , Roy Della M. , Owen Edwin L. , Chiroff Richard T. , White Rodney A. 
Published: December 2004

AbstractBy means of the newly developed Replamineform process, the unique pore microstructures found in the skeletal calcium carbonate of certain reef corals can be replicated or reproduced with high precision in a wide variety of materials suitable for hard tissue implant and prosthetic applications. The advantages of fabricating porous biomaterials with this method include closely controlled size of both the pore diameters and the diameters of the pore interconnections, and virtually complete interconnection of the uniformly spaced pores. These properties are of great importance in implant devices, because tissue ingrowth, the stimulation of new bone formation, the suppression of undersirable scar tissue, the inhibition of adverse body responses, and firm biological fixation of the implanted material all depend upon the nature of the pore‐microstructure configuration. Replamineform preparation of Al2O3, TiO2, hydroxyapatite, silver, Co‐Cr‐Mo alloys, and polymers is described in detail, and the characterization procedures used to determine the physical and structural properties of their materials are discussed. A few of the routinely measured characteristics include (1) quantitative computerized SEM image analysis for determining the volume, size and shape distributions of the macro and microporosity and the grain size measurement of the solid: (2) nondestructive x‐radiography of specimens to reveal any internal defects; (3) mechanical strength measurements of randomly selected specimens. Experimental results up to now clearly demonstrate the superiority of microstructures imparted to metals, ceramics, and polymers with the Replamineform process.
Tissue ingrowth of replamineform implants
Authors: Chiroff Richard T. , White Eugene W. , Weber Jon N. , Roy Della M. 
Published: December 2004

AbstractThe Replamineform process, a new technique for the fabrication of porous hard tissue implant materials which replicates the skeletal configuration of certain marine invertebrates, was used to manufacture 1 cm long by 0.5 cm diam cylinders. The inherent advantages of porous configurations obtained through this process are controlled, uniform pore size controlled pore‐microstructure ratio, and complete interconnection of pores. The specific materials studied were chrome‐cobalt‐molybedenum alloy, αAlO3, hydroxyapatite prepared by hydrothermal conversion, and the basic (aragonite) CaCO3 skeleton of the coral genus Porities. The implants were placed in the cancellous bone of the distal femora and proximal tibiae of adult, mongrel dogs and analyzed at 8 weeks for tissue response and ingrowth. Uniformly, new bone was found to grow into the pores of these materials and become normally mineralized. These findings were determined by microradiography, scanning electron microscopy, electron microprobe analysis, and histology. No evidences of infection, rejection, or encapsulation were seen. In the case of those CaCO3 implants left in place for 1 year, there was almost complete resorption of the cylinders, with both bony trabeculae and unmineralized collagen (presumably osteoid) found at the sites of insertion.
Two‐year biocompatibility study of ORNL graphite
Authors: Kenner G. H. , Williams W. S. , Lovell J. E. , Eatherly W. P. 
Published: December 2004

AbstractA new grade of graphite—isotropic, fine‐grained, and of superior strength—has been produced at the Oak Ridge National Laboratory. The possibility of using this material in orthopedic implants is under study at the University of Illinois. As part of this program, plugs 1/8 in. in diam were inserted in holes drilled in the proximal femur of 2 groups of 8‐week old male rabbits. The groups were sacrificed at the end of 1 and 2 years. A single i.m. injection of achromycin was given 2 days prior to sacrifice. Thin sections of the plugs and surrounding tissue were examined by microradiography and optical microscopy (white light, polarizing, and fluorescent). All bone was normal. Minimal evidence of irritation or fibrous encapsulation appeared.
Dimensional behavior of curing bone cement masses
Authors: de Wijn J. R. , Driessens F. C. M. , Slooff T. J. J. H. 
Published: December 2004

AbstractThe curing of bone cements is accompanied by release of polymerization heat and, hence, by a temperature rise of the curing cement mass. This temperature rise causes expansion of enclosed air bubbles and evaporation of the volatile monomer. An overall expansion of 3 to 5 vol % has been mentioned in the literature. It has often been stated that this expansion favours the fixation of metal endoprostheses in the marrow cavity of bone.To check for the influence of this expansion on linear dimensions of the cured cement mass we filled stainless steel cylinders with a precision bore of 22,000 ± 0,005 mm and a length of 120 mm with bone cement. After curing of the cement in a environment of 37°C the resulting cement rod was released from the cylinder and the diameter of the rod was measured at 37°C.The influence of the “foaming effect” on the transverse dimensions of the rods was studied by curing the cement at 37°C and 2 atm air pressure in a high‐pressure‐vessel. This method of curing eliminates porosity in the cement almost completely, so that curing shrinkage is to be expected rather than expansion of the cement mass.The results indicate that a volumetric expansion of the cement during curing of cylindrical rods in laboratory experiments, can be accompanied by a linear diametrical shrinkage of the cement mass. The explanation of this phenomenon is to be sought in the fact that the volumetric expansion takes place at a time when the cement is still plastic; by the formation of gas bubbles, the cement is forced in longitudinal direction into the cylinder and when the temperature of the mass has passed through a maximum, the cooling of the cement mass results in a thermal shrinkage of approximately 0.4% linearly.Extrapolating this laboratory result to a clinical situation one might doubt whether the overall expansion of bone cements during curing will result in a permanent positive pressure on the walls of marrow cavity and whether it will contribute to a better fixation of endoprostheses than in the case of a, still hypothetical, nonporous cement.
A proposed specification for acrylic bone cement
Authors: Haas S. S. , Dickson G. , Brauer G. M. 
Published: December 2004

AbstractA proposed specification covering handling characteristics and physical and chemical properties of bone cement composed primarily of methyl methacrylate has been prepared on the basis of data from the authors' studies and from various other sources. Under handling characteristics, requirements included relate to dough, handling and setting time, proper plasticity for insertion and temperature rise on setting. Mechanical properties specified include compressive strength and indentation and recovery characteristics. Maximum limits are proposed for water sorption and solubility. Suggested packaging requirements are also included.
Biodegradable material for bladder reconstruction
Authors: Agishi T. , Nakazono M. , Kiraly R. J. , Picha G. , Nosé Y. 
Published: December 2004

AbstractThe objective of this study was to develop a biodegradable material for use in reconstructive surgery of the bladder to serve a temporary function until normal regrowth of the host's tissue is completed. The biodegradable material can serve as a base over which the new bladder can regenerate. At the conclusion of the regrowth of the new tissue, the temporary material could be consumed by the body and therefore not have to be removed.Material evaluation showed that 70% acetic anhydride treated bovine pericardium was digested and dissolved in 4 weeks when implanted subcutaneously in dogs. Based upon this, supplementation of the bladder using this material was performed on 5 dogs. One dog showed urinary leakage and was sacrificed after 1 week. In 3 dogs examined 4, 6, and 48 weeks after implantation, respectively, the implanted material had been dissolved. In one animal autopsied at 10.5 months, a small remnant of the material still remained. Postoperative observation of the animals, excretory pyelocystograms and cystometry confirmed that the material applied was useful for experimental urinary bladder supplementation.