bluuebunny/crossref_metadata_2025 huggingface dataset:
Adsorption of proteins onto hydrophobic polymer surfaces: Adsorption isotherms and kinetics
Authors: Lee Randy G. , Kim Sung Wan
Published: December 2004

Adsorption 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

The 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

A 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

The 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

An 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

Medical 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

A 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

Teflon 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

Thermal 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

The 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

The 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

Cyclic 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

The 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

A 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

Using 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

By 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

The 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

A 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

The 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

A 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

The 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.
Morphological and biomechanical aspects of Al2O3 ceramic joint replacement. Experimental results and design considerations for human endoprostheses
Authors: Griss Peter , Heimke Günther , von Andrian‐Werburg Hanns , Krempien Burkhard , Reipa Susanne , Lauterbach Hans J. , Hartung Hans J.
Published: December 2004

Four different acetabular replacement designs and 2 femoral head replacement designs made out of high density alumina ceramic have been tested in sheep with postoperative survival times of up to 11 months (Frialit 99: Al2O3 99.6%, MgO 0.4%).

It can be concluded from these experiments that a cement free implantation technique with alumina requires a primary rigid fixation of the implant to bone, with the possibility for new bone growth along the ceramic and into grooves and macroscopic holes for further interdigitation. Three different solutions for the acetabular component can be recommended for human application.

In addition, an all ceramic femoral prosthesis has been tested for bending strength in its neck region. Twenty prostheses have been fractured, all of which showed values for bending strength far higher than the physiological neck fracture level (900 kp/cm2). The present state of development of all ceramic prostheses is discussed. Up to now, the development of fibrous tissue between the bone and the ceramic implant has caused reservations with human implantation. The direct definite anchorage problem has to be resolved first.
Some factors affecting dental implant design
Authors: Privitzer E. , Widera O. , Tesk J. A.
Published: December 2004

The present investigation is concerned with answering some of the questions which arise when discussing the success or failure of endosteal implants on the basis of the resulting stresses caused in the surrounding bone structure. In particular, the questions examined are: 1) What affects do variations in the mechanical properties of the implant, an encapsulating membrane and the surrounding bone, have on the stress distribution? 2) Are some implant designs more affected than others, as indicated through variation of bone properties? and 3) What is the affect of an encapsulating membrane and how does a change in its thickness affect the stress distribution? A similar study was conducted on a simulated tooth, so that a comparison may be made between implant and tooth related stress distributions. The method of analysis used to obtain answers to these questions is the finite element method.

Results of the investigation show that for a fixed implant geometry, a change in implant properties causes only minor changes in the bone stress distribution. A change in the membrane and bone properties, however, has a greater affect on the resulting stress distribution. It is also shown that the presence of a protective membrane has a beneficial affect on the stress distribution in the surrounding bone structure and that an optimum thickness can be estimated. Finally, the results show that some implant designs create a situation which results in stronger dependence of stress upon the properties of the surrounding bone.
Alumina and zirconia coated vitallium oral endosteal implants in beagles
Authors: Cranin A. Norman , Schnitman Paul A. , Rabkin Michael , Dennison Thomas , Onesto E. J.
Published: December 2004

The purpose of this study was to assess the addition of a ceramic coating upon a Vitallium implant to increase the implant's biologic acceptability in the oral environment. The mandibular premolar teeth in 9 adult beagle dogs were removed bilaterally and these areas allowed to heal for 6 weeks. Ceramic coating with either Al2O3 or ZrO2 was carried out by flame spray deposition upon Vitallium anchor implants (9 of each), and the implants placed into the 18 healed premolar areas. Clinical and radiographic evaluation was conducted by 2 independent investigators over a 32 week period. Implants which exhibited mobility greater than II on a scale of 0 to III, at intervals of one‐half, were judged unsatisfactory. After 19 weeks, all 9 Al2O3 coated implants and 5 ZrO2 coated implants were rated unsatisfactory. After 32 weeks, 4 ZrO3 coated implants were in situ with 0 or I mobility. Radiographically the width of the peri‐implant space increased in direct proportion to both time and mobility. Histologic sections demonstrated encapsulating dense fibrous connective tissue which was oriented parallel to both ZrO2 and Al2O3 implants. Results suggest the zirconia used is a superior ceramic coating to the alumina. Neither seemed to increase biologic acceptability over uncoated Vitallium implants.
Development of needles and sutures for microsurgery
Authors: Roberts W. N.
Published: December 2004

At present, the smallest needle commonly available is about 130 μm in diameter in combination with a suture of about 25 μm in diameter. Marked reductions in size, particularly of the needle, are advantageous for microvascular surgery.

A needle of about 70 μm in diameter, welded to a suture of about 18 μm diameter, has been developed. In initial tests, it has performed satisfactorily in the repair of the carotid artery of the white rat. It is shown that the basic properties of materials severely limit further reductions in the size of needles and sutures.
Cell adhesion to polymeric materials: Implications with respect to biocompatibility
Authors: Ratner Buddy D. , Horbett Thomas , Hoffman Allan S. , Hauschka Stephen D.
Published: December 2004

The adhesion of radio‐labeled chick embryo muscle cells to the surfaces of radiation grafted hydrogels and other polymeric materials was measured in vitro. The degree of adhesion was determined by measuring the percentage of cells which remained adherent to the surfaces after 180 min of contact time (plating efficiency). Plating efficiency was found to vary between 2 and 94% depending on the nature of the surface. Preadsorption of albumin, γ‐globulin or fibrinogen markedly affected subsequent adhesion of cells. Radiation grafted poly(2‐hydroxyethyl methacrylate) and poly(N‐vinyl‐2‐pyrrolidone) hydrogels on silicone rubber demonstrated exceptionally low adhesiveness in this assay. The potential for using this cell adhesion assay as a general screening test for biomaterials is discussed.
A failed Vitallium/stainless steel total hip replacement: A case report with histological and metallurgical examination
Authors: Gruen T. A. , Amstutz H. C.
Published: December 2004

A case of a failed total hip replacement consisting of a Vitallium hip socket and a stainless steel femoral head prosthesis is presented. The mixed‐metal combination and inadequate design resulted in severe abrasive wear and fretting corrosion of the bearing surface, and the accumulation of stainless steel wear debris and corrosion products in the periarticular tissues was extensive.

The tissue response was primarily fibrotic scarring with severe histiocytic and mild foreign body giant cell reaction. Despite the massive accumulation of wear debris and corrosion products, however, there was minimal chronic inflammation and no acute inflammation.
Determination of fluorocarbon in blood
Authors: Stein T. P. , Robbins Winston K. , Brooks Helene B. , Wallace Herbert W.
Published: December 2004

Because fluorocarbons can dissolve relatively large quantities of oxygen and carbon dioxide, there is considerable interest in utilizing them to develop new methods of extracorporael circulation, artificial red blood cells, and liquid breathing techniques. A method for the assay of fluorocarbon in blood is presented. The fluorocarbon is extracted from the blood with toluene, and fluoride is released from the fluorocarbon in the toluene extract by reaction with sodium biphenyl. The inorganic fluoride is then extracted with aqueous sodium acetate, the pH of the extract is adjusted, and the activity of the fluoride ion is read with a fluoride‐specific ion electrode. The assay was effective for fluorocarbon concentrations in the range 1 to 30 ppm.
Platelet adhesion and contact activation time tests on HEMA coated cellulose acetate membranes
Authors: Muzykewicz K. J. , Crowell E. B. , Hart A. P. , Schults M. , Hill C. G. , Cooper S. L.
Published: December 2004

Surface modification of cellulose acetate dialysis membranes was carried out by 60Co radiation induced graft copolymerization of the hydrogel, hydroxyethyl methacrylate (HEMA). The degree of grafting was controlled by varying the HEMA monomer concentration in the grafting solution and the radiation dose. A continuous flow platelet adhesion test was designed which allows testing under conditions more closely approximating hemodialysis than other small scale in vitro tests. Platelet adhesion on treated membranes fell substantially with increasing surface HEMA concentration. The presence of HEMA on the membrane surface did not affect the membrane activated clotting times significantly.
Correlation of in vivo collagen degradation rate with in vitro measurements
Authors: Yannas I. V. , Burke J. F. , Huang C. , Gordon P. L.
Published: December 2004

The rate of in vitro enzymatic degradation of various materials based on collagen has been determined by a novel mechanochemical method, and has been compared with the extent of degradation resulting from subcutaneous implantation in guinea pigs. In vitro data correlate well with in vivo data. It is suggested that the simple in vitro method described is an effective means of screening a large number of materials based on collagen for their ability to resist degradation during implantation in animals.
Reaction associated with a silicone rubber gel: An experimental study
Authors: Rigdon R. H. , Dricks Alfred
Published: December 2004

A blend of Silastic 382 (Room Temperature Vulcanizing, RTV) Medical Grade silicone oil and a catalyst was prepared in vitro, in both the catalyzed and noncatalyzed state, and injected subcutaneously in mice, rats, and rabbits. When properly blended, this catalyzed material, referred to as “silicone gel,” formed a soft rubbery mass that remained at the site of injection. Properly catalyzed silicone rubber gel produces no macroscopic inflammatory reaction, attracts few polymorphonuclear leucocytes, and after 5–6 days a thin fibrous capsule begins to form around the gel. No degeneration of the silicone gel was observed during the 62 days of this experiment. Additional rats with this silicone gel have been under observation for 8 months and clinically have shown no changes in the local mass of silicone. If the catalyst is partly oxidized when added to the silicone fluid, the degree of gelling is much less. A local mass usually forms at the site of injection with some of the fluid diffusing into the tissue, forming minute cysts. The inflammatory reaction is characterized by polymorphonuclear leucocytes, associated with many macrophages and giant cells phagocytizing oil droplets and particles of the diatomaceous earth. The pathogenesis of the inflammatory reaction is discussed, referring to the ionic change and the emigration of polymorphonuclear leucocytes to particles of plastics embedded in tissue.
Long‐term experience with poly(glycol monomethacrylate) gel in plastic operations of the nose
Authors: Voldřrich Z. , Tománek Z. , Vacík J. , Kopečcek J.
Published: December 2004

Between 1964 and 1970 the authors implanted Hydron gel in 62 patients with nose malformations. The cosmetic defects most freqently operated on were the saddle, and scoliosis of the nasal dorsum. By the end of 1973,39 of the total number of cases were checked again. In two cases, the gel had to be removed shortly after the operation because of local inflammatory changes. No signs of hypersensitivity could be detected. Calcifications were detected by x‐ray examination in 54.2% of the cases. Thirty‐four of the patients subjected to the checkup were satisfied with the results of their operations. The authors considered the results to be very good in 16 cases, and unsatisfactory in 6 cases. Calcifications detected by x‐ray examination did not affect the final cosmetic effect.

None of the examined patients had any complaints in connection with longterm application of the gel. Hydron gel seems to be a suitable implant material in plastic operations of the nose.
Reconstruction of the canine Achilles and patellar tendons using Dacron mesh silicone prosthesis. I. Clinical and biocompatibility evaluation
Authors: Amstutz H. C. , Coulson W. F. , David E.
Published: December 2004

Surgical replacement of the Achilles and patellar tendons using Dacron mesh silicone prostheses was performed in 15 mature beagle dogs. This part of the study includes clinical evaluation, gross inspection at autopsy of regrown tendons, and histological determination of biocompatibility of prosthetic implants.

Functional continuity and integrity of prosthetic patellar tendons have been established by evaluating the biologic–prosthetic interface and the mechanical properties of regrown tendon tissue around and through the Dacron silicone replacements. Results of prosthetic Achilles tendons were less satisfactory because of difficulties in suturing to a muscle and its fascia. Although the prosthetic tendon did not regrow through the tube, it provided a structure for regrowth around it. The regrown tendons became nearly ten times the normal crosssectional area after three to four months and decreased to two to three times after 13 months.

Histological studies indicate that in the absence of infection, the Dacron mesh silicone tendon was well tolerated for periods up to 13 months. Overall results are encouraging and warrant further investigation although the regenerative capacity of human patellar and Achilles tendons is unknown.
Hair sampling for chromium content following Charnley hip arthroplasty
Authors: Owen R. , Meachim G. , Williams D. F.
Published: December 2004

The chromium content of hair has been studied by neutron activation analysis of samples from 62 patients following a Charnley unilateral or bilateral hip arthroplasty by an artificial joint of stainless steel against polyethylene, inserted three to five years previously. The patients lived in the North Wales area of the British Isles. Hair chromium content was also studied in 51 control subjects of similar age to that of the patients, from the same geographical area and often from the patients' own households.

Chromium content was recorded as parts per million (ppm) of hair weighed and analyzed in the state received, without preliminary ashing or chemical “washing” of the samples in the laboratory. Fifty of the 51 control subjects showed less than 2 ppm chromium in hair; one showed 2–5 ppm; none showed more than 5 ppm. Fifty‐nine of the 62 patients showed less than 2 ppm chromium in hair; three showed 2–5 ppm; none showed more than 5 ppm.

Attention is drawn to certain practical aspects when collecting hair samples for chromium analysis. The use and validity of hair sampling as one method of screening for systemic chromium accumulation following implant surgery is discussed. The method may be a useful adjunct to monitoring of chromium levels in blood samples. In this preliminary study, hair sampling has given no evidence of any major risk of systemic chromium accumulation in patients using a Charnley arthroplasty for periods of up to five years; no conclusion can be made concerning periods longer than this. The findings do not exclude systemic reactions of the hypersensitivity type, since this type of reaction could develop to only small amounts of chromium.
Effects of solvent casting copolymer materials as related to mechanical properties
Authors: Bagrodia Shriram , Wilkes Garth L.
Published: December 2004

Using a well characterized series of styrene butadiene triblock copolymers a systematic study was carried out to determine the influence of casting solvent, used for film preparation, on the final mechanical properties. The results clearly indicate that in the range of styrene contents of 30–40 mol %, the modulus behavior is greatly affected as the solubility parameter of the casting solvent, δ, is varied. Specifically, the modulus increases as δ increases to the value of polystyrene. At lower or higher styrene content, the properties are influenced but to a much lesser degree. Other mechanical properties measured were yield stress and breaking stress. The ramifications of these data are discussed in light of preparing prosthetic material via solvent casting.
The biostability of silicone rubbers, a polyamide, and a polyester
Authors: Roggendorf E.
Published: December 2004

A biostability test program was designed after evaluation of the relevant literature on in vivo aging phenomena in plastics and elastomers. The program comprised macroscopic, microscopic, mechanical, and physicochemical investigations. Five silicone rubbers, one polyester, and one polyamid were tested as to their aging behavior and their suitability for long‐term implantation in the human body was assessed. In order to be able to state the applicability of materials used for endotheses, the various aging phenomena had to be divided into three groups, viz. unspecific, relative, and absolute indications of aging or unserviceability.

Changes due to aging were found in all types of implanted plastics and elastomers. Thus, the formation of layers on inlay surfaces occurred regularly and the same would apply to changes in mechanical characteristics during the tensile test. Aging processes resulting in total unserviceability were fragmentation and crazing in the polyester and polyamide sheetings. Other aging phenomena which will easily fit into the classification given above are changes in electrical test values, protein, and lipid depositions without stronger absorptive adhesion, crystallizations on the surface of silicone vulcanizates, and chemical changes in the polyester and polyamide sheetings.

Following the assessment of the materials used for endotheses, the test methods used have been evaluated with regard to their suitability for the testing of biostability.
Transient diffusion effects in the study of early platelet adhesion
Authors: Butruille Y. A. , Savitz S. R. , Leonard E. F. , Litwak R. S.
Published: December 2004

In the study of interactions of blood with artificial surfaces, it is common practice to wet these surfaces with a saline solution before exposing them to blood. The effect of this procedure on subsequent adhesion of blood platelets has been investigated both theoretically and experimentally, with a spinning disc apparatus. A large part of the observed delay in the initiation of platelet adhesion when using this apparatus is attributed to the time involved in displacing the prewetting fluid and bringing platelets near the surface. This observation is relevant to speculations of other researchers about the time course of adhesion‐related reactions at the surface‐proper. Other theoretical solutions are developed for the transient Leveque problem, which relates to a uniform shear‐flow near a surface, and for a stagnation point apparatus. These solutions are compared with delay effects noticed in experimental data published by others.
The influence of surface chemistry on implant interface histology: A theoretical basis for implant materials selection
Authors: Clark A. E. , Hench L. L. , Paschall H. A.
Published: December 2004

A theory is proposed stating that an ideal implant material must have a dynamic surface chemistry that induces histological changes at the implant interface which would normally occur if the implant were not present. Evidence for the validity of this theory is provided with a series of bone‐implant studies which result in stable interfacial osteogenesis under specific implant surface chemistry conditions. Insufficient or excess surface ion concentrations produce negative osteogenesis and fixation results. Implantation of osteogenic implants in soft tissues also produces undesirable histological responses as proposed in the theory. A variety of surface chemical analyses of the implant are reviewed which provide a scientific basis for the implant surface theory.
Biocompatibility of materials for total joint replacement
Authors: Escalas Felix , Galante Jorge , Rostoker William , Coogan Philip
Published: December 2004

The clinical use of total joint prostheses demands absolute biocompatibility of the materials employed.

The purpose of this experiment was the bioassay of some materials considered as possible candidates for use in total joint prostheses as load‐bearing members or as wear‐resistant surfaces.

Some materials already in use were also tested. 316L stainless steel was used as a control. The materials were implanted as a standardized rod and in particulate form.

An average of 12 samples per material were implanted in soft tissue for six months and a total of 145 rabbits were used in this study. Twenty‐five materials including metals, polymers, and ceramics were tested in solid and powdered form.

A semiquantitative evaluation of local tissue reaction and a study of organs was performed.

Polymers and metallic materials showed in general a mild tissue reaction. Ceramics, which some authors describe as the best tolerated materials, elicited variable tissue responses. Some of these (glass–ceramics) presented very poor tissue tolerance. The least reactive, titanium oxide, titanium aluminate, and aluminum oxide, presented a degree of tissue reaction comparable to that of corrosion resistant metals, but not superior to them. Moderate reactivity was the general rule for particulate materials except for the Pyroceram glass–ceramics, polyimides, and Teflon. Ultrahigh molecular weight polyethylene in particulate form elicited a rather cellular tissue response, a fact to be considered when projecting long‐term results in total joint arthroplasty.

No pathological changes compatible with systemic toxicity by materials tested were observed in the study of the organs.
Tendon grafting with glutaraldehyde fixed material
Authors: McMaster William C. , Kouzelos Jack , Liddle Shardon , Waugh Theodore R.
Published: December 2004

An evaluation of 0.2% buffered glutaraldehyde fixed tendon as a potential tendon replacement prosthesis was evaluated in rabbit and chicken models. In vivo implantations were done to determine compatability, function, and strenght of grafts, Autogenous fresh grafts were used as controls in the strenght in tension compares favorably to a fresh autogenous control. These preliminary evaluations indicate a useful potential for this fixed biomaterial as a tendon prosthesis.
An in vitro study of bacterial response to inert and reactive metals and to methyl methacrylate
Authors: Gristina Anthony G. , Rovere George D. , Shoji Hirumo , Nicastro Joseph F.
Published: December 2004

The clinical use of inert materials for internal fixation and joint replacement decices is increasing rapidly; studies on the effect of these materials on bacteria and host resistance t infection have not kept apace. Any substance placed within the body may interfere with host–parasite interaction, either by its physical presence or by physiohcemical activity at its interface with the surrounding tissue. Either mechanism, by altering the normal host defense mechanisms, may promote or retard bacterial growth. Bacterial growth may also be altered if a trace element essential to or inhibitory to the bacteria or an element that antagonizes or potentiates humoral antibaacterial systems is leached from the substance. We have tested bacterial growth and inhibition in vitro in the presence of substances used as implant materials: surgical silver, iron, zinc‐coated galvanized iron, aluminum alloy, stainless steel, Vitallium, and methyl methacrylate. Our results showed: (1) metals that have low grades of tissue ractivity and little bacteriotoxic effect provided a framework along which bacterial growth and propagation occurred; (2) metals that have higher levels of cellular reactivity, specifically aluminum and galvanized wire, caused selective bacterial toxicity, The in vitro response of bacteria to methyl methacrylate was similar to that of Vitallium to methyl methacrylate.

These studies led us to speculate that, if similar phenomena occur in vivo, bacterial growth and dissemination might be increased when an inert implant material was used and decreased when the implant material was more reactive.