bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aging test and dynamic fatigue test of apatite‐wollastonite‐containing glass ceramics and dense hydroxyapatite
Authors: Kitsugi Toshiaki , Yamamuro Takao , Nakamura Takashi , Kakutani Yoshiaki , Hayashi Tetuya , Ito Setsuro , Kokubo Tadashi , Takagi Masataka , Shibuya Takehiro 
Published: December 2004

AbstractThe purpose of this study is to examine the changes in mechanical strength of two bioactive ceramics in living tissue. An aging test and dynamic fatigue test were performed using apatite‐wollastonite‐containing glass ceramics (A · W – GC) and dense hydroxyapatite (HA). Specimens (5mm × 5mm × 25mm, abraded with No. 2000 Al2O3 powder) were implanted into subcutaneous tissue of rats for varying periods of time. The bending strength of aged samples was measured by the three‐point loading method. The bending strength of A · W – GC was greater than that of HA (P < 0.001). There was no reduction in bending strength for both A · W – GC and HA in living tissue. The n value of both A · W – GC and HA did not decrease significantly after implantation as assessed by the results of the dynamic fatigue test according to analysis of covariance. SEM‐EPMA showed that Si and Mg contents decreased, Ca content did not change, while P content increased in the surface of A · W – GC. The area where x‐ray intensity changed increased moderately after implantation. There were no changes in Ca and P at the interface between HA and soft tissue. In macroscopic and microscopic observations, specimens were found to be encapsulated with a thin layer of connective tissue. Foreign body giant cells, obteoblasts, or osteoclasts were not observed in the soft tissue. There was no bonding between ceramics and soft tissue.
The influence of bioglass on the growth of fibroblasts
Authors: Matsuda T. , Yamauchi K. , Ito G. 
Published: December 2004

AbstractThe influence of Bioglass (BG) on the growth of L cells was studied by means of tissue culture, to get an idea on its bonebonding mechanism. Growth rate of L cells on BG was lower than that on the control silica glass (SG). L cells on BG diminished in size and took up long and slender polygonal shapes with radially spread long pseudopods, which probably meant that the cell cycle was detained at the synthetic period. From these findings, BG is thought to have an inhibitory effect on the growth of L cells, which might arrest the fibrous tissue encapsulation and allow bonding with bone.
The use of coral as a bone graft substitute
Authors: Guillemin G. , Patat J.‐L. , Fournie J. , Chetail M. 
Published: December 2004

AbstractExperiments have been performed to investigate the use of coral skeletons as bone graft substitutes. Skeletal fragments of different coral genera were implanted into cortical and spongy bone defects and used to bridge transcortical resections in the femur. The implant site was monitored for up to 18 months. Radiographically, both cortical and spongy bone defects were at least partially filled by new bone after 8 weeks while the implants underwent continuous resorption. Coral resorption and replacement by new tissue was also observed in the transcortical resections. The process of resorption was attributed to the enzymatic attack, especially carboanhydrase. This was confirmed by experiments in which dogs were implanted with coral in transcortical resections and treated daily with acetazolamide, a carboanhydrase inhibitor; the absorption appeared delayed and the reseections failed to heal.
An in vitro study of the adhesion of blood platelets onto vascular catheters. Part I
Authors: Engbers G. H. M. , Dost L. , Hennink W. E. , Aarts P. A. M. M. , Sixma J. J. , Feijen J. 
Published: December 2004

AbstractThe adhesion of human blood platelets onto vascular catheters was studied using a specially designed perfusion chamber. Polyurethane catheters were exposed to citrated human blood for different periods (up to 20 min) and at different wall shear rates (190, 260, 330 sec−1). The rate of platelet adhesion was determined using 111In‐labeled platelets, while the morphology of adhering platelets was investigated using scanning electron microscopy. A linear increase in platelet adhesion was found within the first 10 min of perfusion, after which a plateau value was reached. The number of adhering platelets did not vary significantly with the shear rates applied, which may indicate that within the range of shear rates studied, the adhesion of platelets onto the catheter surface is mainly determined by the rate of the reaction between the platelets and the material surface. Catheters coated with a conjugate of heparin and albumin showed a four‐ to five‐fold reduction in platelet adhesion as compared to uncoated catheters. This reduction in platelet adhesion was not only due to the presence of albumin moieties at the surface but also to the presence of heparin residues in the adsorbed albumin‐heparin conjugate.
Adsorption of low density lipoproteins onto selected biomedical polymers
Authors: Dong D. E. , Andrade J. D. , Coleman D. L. 
Published: December 2004

AbstractThis study examines the interaction of human low density lipoprotein (LDL) with a select group of biomedical polymers. The adsorption characteristics of LDL on cured filler‐free poly(dimethyl Siloxane) (C‐PDMS), Biomer, Cardiomat 610, Kraton 1650, poly(hydroxyethyl methacrylate) (PHEMA) and glass are presented. Adsorption of LDL to charged hydrophilic glass control surfaces occurred rapidly, reaching plateau concentrations within one minute (0.19 ± 0.01 ug/cm2). Adsorption of LDL to polymer surfaces appeared to be dependent upon both the polymer hydrophobicity (or apolar nature), and flexibility (or dynamic nature) at the interface. Increased surface concentrations were observed for Biomer (0.32 ± 0.01 ug/cm2) as well as other polymers which exhibited both hydrophobic and elastomeric próperties. Temperature changes between 25°C and 37°C were found to significantly influence the surface concentration of LDL on Biomer (0.16 ± 0.01 ug/cm2 at 25°C versus 0.32 ± 0.01 ug/cm2 at 37°C). A lipid core phase transition at 36°C was believed to be responsible for the temperature influence. Preliminary competitive adsorption studies of LDL with albumin (HSA) and serum on silicone surfaces suggests that LDL adsorption occurred rapidly and preferentially (0.25 ± 0.01 ug/cm2 for LDL alone; 0.33 ± 0.01 ug/cm2 for LDL + HSA; 0.15 ± 0.01 ug/cm2 LDL + serum). Preliminary studies on the role of LDL in calcification were not conclusive. It can be concluded that LDL adsorption is dependent upon polymer hydrophobicity, flexibility and temperature. Competitive adsorption experiments suggests that LDL may have substantial influence on protein adsorption.
Thick‐section histometry of porous hydroxyapatite implants using backscattered electron imaging
Authors: Holmes Ralph E. , Hagler Herbert K. , Coletta Craig A. 
Published: December 2004

AbstractA histometry system has been developed to measure bone ingrowth into porous hydroxyapatite implants utilizing the backscattered electron image of thick sections. The system consists of a scanning electron microscope (SEM) with backscattered electron detector, digital beam controller, minicomputer based image digitization, and microcomputer based image processing, point counting, and lineal analysis. The SEM backscattered electron imaging mode yields high tissue contrast and sharp tissue boundaries, substantially reducing the lost cap and projection effect errors of thick sections. High‐resolution digitization of the image substantially reduces the standard error of the estimates. By using the digitized image the tedious process of filtering artifacts and recording actual point counts, intersections, and intercept lengths is delegated to computer software. Performance of this system in a recent study demonstrated substantial ease of operator use and speed of measurement. In the absence of a digital beam controller an inexpensive video digitizer circuit board may be used to digitize photographic prints of the SEM images. The combination of increased accuracy, precision, operator ease, and speed suggests that this system can be useful for soft tissue‐bone‐implant histometry.
Chemically modified collagen: A natural biomaterial for tissue replacement
Authors: Nimni M. E. , Cheung D. , Strates B. , Kodama M. , Sheikh K. 
Published: December 2004

AbstractGlutaraldehyde crosslinking of native or reconstituted collagen fibrils and tissues rich in collagen significantly reduces biodegradation. Other aldehydes are less efficient than glutaraldehyde in generating chemically, biologically, and thermally stable crosslinks. Tissues crosslinked with glutaraldehyde retain many of the viscoelastic properties of the native collagen fibrillar network which render them suitable for bioprostheses. Implants of collagenous materials crosslinked with glutaraldehyde are subject long‐term to calcification, biodegradation, and low‐grade immune reactions. We have attempted to overcome these problems by enhancing crosslinking through (a) bridging of activated carboxyl groups with diamines and (b) using glutaraldehyde to crosslink the ϵ‐NH2 groups in collagen and the unreacted amines introduced by aliphatic diamines. This crosslinking reduces tissue degradation and nearly eliminates humoral antibody induction. Covalent binding of diphosphonates, specifically 3‐amino‐1‐hydroxypropane‐1, 1‐diphosphonic acid (3‐APD), and chondroitin sulfate to collagen or to the crosslink‐enhanced collagen network reduces its potential for calcification. Platelet aggregation is also reduced by glutaraldehyde crosslinking and nearly eliminated by the covalent binding of chondroitin sulfate to collagen. The cytotoxicity of residual glutaraldehyde—leaching through the interstices of the collagen fibrils or the tissue matrix—and of reactive aldehydes associated with the bound polymeric glutaraldehyde can be minimized by neutralization and thorough rinsing after crosslinking and storage in a nontoxic bacteriostatic solution.
The effect of surface preparation on metal/bone cement interfacial strength
Authors: Bundy K. J. , Penn R. W. 
Published: December 2004

AbstractThis study is concerned with finding practical ways for strengthening metal/bone cement (M/BC) interfaces via surface alterations and identifying fundamental mechanisms underlying M/BC adherence. Shear strengths have been inferred from torsion tests using shear lag analysis. The variables examined with regard to their effects on interfacial strength are substrate material, surface roughness, interface porosity, passivation and sterilization, surface cleaning procedures, and use of bone cement precoated metals. M/BC interfaces can be substantially strengthened by applying the bone cement to the metal with high pressure. This would be a practical way to strengthen interfaces for precoated implants. The acrylic polymerized in vivo would employ the usual low pressure method. Otherwise, the main method for improving M/BC interfaces is through changing surface topography. Cleaning or chemical treatments have relatively minor effects. Roughened surfaces, as expected, produce stronger interfaces. Dramatic strength improvements occurred with a porous arc plasma sprayed layer on the substrate. Surprisingly, highly polished surfaces also improve interface strength (compared to less polished surfaces). The hypothesis is advanced that M/BC adherence depends upon superposition of mechanical interlocking and atomic interaction effects, with the latter predominating for finer finishes and vice versa. Differences exist between materials which are independent of roughness.
Effects of alkyl grafting on surface properties and blood compatibility of polyurethane block copolymers
Authors: Grasel Timothy G. , Pierce Jeffrey A. , Cooper Stuart L. 
Published: December 2004

AbstractIn order to probe the factors which affect the interaction between the surface of a multiphase polyurethane material and blood, a series of butanediol‐chain‐extended polyetherurethanes was synthesized. These polyurethanes contained different levels of phase separation, produced by systematically varying the hard segment chemical structure by grafting ethyl and octadecyl groups to the urethane nitrogen atom. Surface characterization using high vacuum, air‐equilibrated, and water‐equilibrated methods was performed. A canine ex vivo arteriovenous series shunt was used to monitor initial platelet and fibrinogen deposition on these polymers. The ex vivo response to these materials, along with contact angle and ESCA surface chemistry, was found to vary with the degree of alkyl derivatization. This study demonstrated that an increase in the degree of phase separation and also the incorporation of long chain (C18) alkyl groups can affect surface properties and improve the short‐term blood compatibility of the underivatized polyurethane.
Adherence of Streptococcus mutans to implant materials
Authors: Fujioka‐Hirai Yumi , Akagawa Yasumasa , Minagi Shogo , Tsuru Hiromichi , Miyake Yoichiro , Suginaka Hidekazu 
Published: December 2004

AbstractThe adherence of Streptococcus mutans OMZ‐176 to six implant materials (polycrystal alumina, single‐crystal alumina, titanium alloy, cobalt‐chromium‐molybdenum alloy, hydroxyapatite, and heat‐curing polymethylmethacrylate resin) was studied in vitro. The change of free energy, which corresponds to the adherence process, was also evaluated for hydrophobic interaction. Adherence of S. mutans to poly‐crystal alumina was lower than adherence to other materials. The adherence of S. mutans to the test materials was highly correlated with the change of free energy, which suggests that hydrophobic interaction plays an important role in the adherence of S. mutans to the implant materials.
Prostacyclin immobilized albuminated surfaces
Authors: Joseph George , Sharma C. P. 
Published: December 2004

AbstractThe adhered platelets on artificial surfaces play a crucial role in inducing thrombosis. Therefore, it is very much desirable to have surfaces which can effectively retard platelet adhesion and aggregation. Prostaglandins like PGI2, PGE1 and PGD2 possesses potent antiplatelet activity, but have very short half life. A chemically stable prostacyclin analog, 10,10‐difluoro‐13‐dehydroprostacyclin (DF2—PGI2) seems to be promising. Polyelectrolyte (PE) synthesized from natural poly cis‐1,4 isoprene has also been found to possess outstanding anticoagulant and antiplatelet activity. Modification of polyethurerethane urea (PEUU) by immobilizing DF2—PGI2 and polyelectrolyte in various combinations using glow discharge technique has been attempted. Surfaces thus modified showed negligible platelet adherence. The inhibition of platelet adherence in presence of inducing agents like fibrinogen, thrombin and ADP was also remarkable. The interactions of albumin and fibrinogen with the modified surfaces were studied using 125I labelled proteins.
Alternative techniques of seeding cultured endothelial cells to ePTFE grafts of different diameters, porosities, and surfaces
Authors: Lindblad Bengt , Wright Seth W. , Sell Ruth L. , Burkel William E. , Graham Linda M. , Stanley James C. 
Published: December 2004

AbstractAttachment of 111Indium‐oxine labeled cultured canine venous endothelial cells to expanded polytetrafluorethylene (ePTFE) grafts was evaluated in vitro. Three alternative seeding techniques were studied in grafts having different diameters, porosities, and surfaces, including: (I) manual milking of blood contiaining endothelial cells within the graft; (II) a two‐step procedure of incubating grafts initially with blood and then with an endothelial cell suspension; and (III) mechanical spinning of grafts filled with blood containing endothelium. Method II had significantly higher cell attachment to the graft (11.6%) than did Method I (1.5%) or III (4.7%). A somewhat higher seeding efficiency was noted in 10‐mm‐I. D. grafts (11.6%) compared to 6‐mm‐I. D. grafts (6.3%). Different graft porosity, created by altering internodal distances, did not cause significant changes in cell attachment (10 m̈m, 13.4%, 30 m̈m, 6.3%; 90 m̈, 16.0%). Fibronectin‐coated surfaces, which should have enhanced cell adhesion, demonstrated a 6.0% cell attachment, a lower efficiency than the 11.6% observed with a blood coating alone. Acetone‐soaked surfaces, which should have predictably exhibited less hydrophobicity, produced quite variable attachments (range 3.4 to 59.7%, mean 23.4%). In the present investigation the best seeding technique was method II, the two‐step incubation procedure. Consistant differences were not noted with various ePTFE graft configurations or surfaces.
Carbon/graphite fiber reinforced poly(methyl methacrylate): Properties under dry and wet conditions
Authors: Ekstrand Karl , Ruyter I. Eystein , Wellendorf Hanne 
Published: December 2004

AbstractThe flexural properties of poly(methyl methacrylate) (PMMA) reinforced with carbon/graphite (C/G) fibers with three different surface treatments were investigated by transverse bend testing after dry and wet storage. The fibers used were (1) commercially available fibers, (2) cleaned fibers, and (3) cleaned and sized fibers. The coating agents of commercial unidirectional and braided C/G fibers as well as impurities on C/G fibers for medical uses were characterized by means of high‐performance liquid chromatography (HPLC). The agar overlay technique was used to assess the cytotoxicity of leachable elements from different fibers and processed composites. Composites with both unidirectional and braided tubular C/G fibers were investigated after storage in water. Fracture stress and flexural modulus decreased when “commercial” fibers were used as reinforcing material. Composites with cleaned and sized fibers gave only minor differences in flexural properties after dry and wet storage. By means of SEM micrographs the adhesion behavior of unsized C/G fibers, epoxy sized fibers were assessed. After water storage a substantial part of the cleaned fibers adhered to the matrix material. The adhesion capacity of the other fibers was reduced since the water absorption caused separation of fiber and matrix.
Experimental demonstration of the immunogenicity of silicone–protein complexes
Authors: Kossovsky Nir , Heggers John P. , Robson Martin C. 
Published: December 2004

AbstractAlthough silicones, as a class, are nontoxic in animal and tissue studies, implanted silicone prostheses and medical devices are associated with various local and systemic host inflammatory reactions. They also have been associated with a form of autoimmune disease. To test the hypothesis that silicones may evoke an immunologically mediated inflammatory reaction, 10 guinea pigs were stimulated for 1 month with intraperitoneal injections of sterile medical‐grade silicone oil admixed with homologous serum and complete Freund's adjuvant. Ten controls were stimulated with salin. Four additional animals were passively sensitized with splenic homogenates from four sensitized animals. Intradermal antigenic challenges consisted of silicone‐homologous serum, pure silicone, saline‐homologous serum, pure silicone, saline‐homologous serum, and purified protein derivative. Cutaneous reaction patterns were graded grossly and microscopically. Silicone‐serum and purified protein derivative antigens evoked three to four times greater palpable lesions in all 10 actively and all 4 passively sensitized animals at approximately 24 h compared to controls. Biopsies showed a moderate to marked lymphocytic infiltrate. Control sites and naive animals showed only edema at the challenge sites. The data suggest that silicone‐protein complexes are potentially immunogenic.
Pluronic F‐127 gel preparation as an artificial skin in the treatment of third‐degree burns in pigs
Authors: Nalbandian Robert M. , Henry Raymond L. , Balko Kenneth W. , Adams Dennis V. , Neuman Norwood R. 
Published: December 2004

AbstractA blinded study was designed to provide qualitative and quantitative evaluation on the possible therapeutic benefits of the use of Pluronic® Polyol F‐127 as a substitute skin in standardized third‐degree thermal burns. Three separate burns, approximately 1600 mm2, were induced on the shaved backs of young, anesthetized pigs. Each animal served as its own control. One burn site was left untreated while the other two sites were covered with coded preparations of the Pluronic® F‐127 gel with additives. Polaroid photographs with a fixed focal‐length camera were taken of all burn sites for planimetry analysis. Biopsies taken confirmed that third‐degree burns were achieved. The pigs were followed for 30 days. The rate of healing of third‐degree thermal burns was significantly accelerated over control sites when treated with Pluronic® Polyol F‐127 plus propylene glycol. When the bacteriostatic agent Garamycin was also added, the rate of healing remained significantly better than untreated controls. With the addition of Piracetam, burn wound healing was actually retarded within 30 days, when applied topically. Thus, wound healing was both accelerated and retarded as a function of the particular Pluronic® preparation used to treat specific burn sites. This experimental modulation of wound healing suggests that the non‐ionic poloxamer, Pluronic F‐127, can significantly enhance the rate of wound healing by some unknown mechanism, possibly by stimulation of epithelial growth factor (EGF).
The influence of surface area on the in vitro cytotoxicity of a range of dental materials
Authors: Meryon Sylvia Diana 
Published: December 2004

AbstractIn the toxicity testing of dental materials the quantity of material used may have a profound influence on the biological response obtained. This was investigated in vitro by assessing the cytotoxicity of equal volumes of nine materials in artificial cavities of three different diameters, chosen to cover the range found in vivo. With seven materials there was a significant increase in toxicity with increasing surface area. The pattern of response of different materials within specific groups was fairly uniform. The degree of toxicity of the test materials relative to controls was also investigated. From the data obtained it is apparent that the maximum cavity diameter appropriate for the material under test must be considered when evaluating the toxicity of dental materials.
Blood hemolysis by PTFE and polyurethane vascular prostheses in an in vitro circuit
Authors: Martz Hugues , Paynter Royston , Losier Michel , Domurado Dominique , Forest Jean‐Claude , Guidoin Robert 
Published: December 2004

AbstractIn order to improve understanding of the appearance of bright yellow stains in vivo (consecutive to the absorption of bilirubin) on a novel microporous, hydrophilic polyetherurethaneurea vascular prosthesis, the in vitro hemolytic activity of the material was compared with expanded polytetrafluoroethylene and silicone rubber. The results show that the tendency of the polyetherurethaneurea to produce free hemoglobin is low, so that the yellow staining observed is likely to be a result of the contact between the polymer and thrombi: Bilirubin is produced because of hemoglobin degradation in the thrombi rather than an active hemolysis on the surface of the prosthesis itself.
Release of corrosion products by F‐75 cobalt base alloy in the rat. III: Effects of a carbon surface coating
Authors: Black J. , Oppenheimer P. , Morris D. M. , Peduto A. M. , Clark C. C. 
Published: December 2004

AbstractA pyrolytic carbon coating was applied to F‐75 chromium‐cobalt‐molybdenum alloy in an effort to reduce the release of corrosion products in vivo. After intramuscular implantation in the rat, a complex pattern of serum and urine concentration elevations of chromium, cobalt, and nickel was seen. The carbon‐coated implants released more chromium and cobalt than uncoated controls, as seen by significantly elevated metal concentrations in serum and urine. Animals receiving carbon‐coated implants showed a high rate of recurrent implant site inflammation. Neoplastic infiltration of the implant site occurred in 3 out of 24 animals with coated implants, but not in any of the 16 animals which received either uncoated F‐75 microsphere or poly(ethylene) particulate implants.