bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue reaction to soft‐tissue anchored percutaneous implants in rabbits
Authors: Jansen J. A. , Paquay Y. G. C. J. , van Der Waerden J. P. C. M. 
Published: May 2005

AbstractThis study reports on the soft‐tissue response to titanium fiber mesh percutaneous implants. The implants were inserted in the backs of 15 rabbits. The surgical procedure was performed in two steps: implantation of the subcutaneous part of the implants and, after 3 months, fixation of the percutaneous part into the subcutaneous part. Two and 6 months after insertion the animals were sacrificed and the implants, with their surrounding tissues, were processed histologically. Light microscopic analysis demonstrated that only one implant showed considerable skin retraction in the percutaneous area. Around the rest of the implants no downgrowth or only a very limited epidermal downgrowth was observed. Furthermore, the fiber mesh material showed good biocompatible behavior. These results confirm the previous finding that sintered titanium fiberweb structures are effective for the stabilization of percutaneous devices located in soft tissues and can improve their performance. © 1994 John Wiley & Sons, Inc.
Fate and biocompatibility of three types of microspheres implanted into the brain
Authors: Menei P. , Croué A. , Daniel V. , Pouplard‐Barthelaix A. , Benoit J. P. 
Published: May 2005

AbstractThe implantation of polymer devices in the brain that release neuroactive drugs locally and in a controlled manner is gaining increasing interest. The fates and tissue reactions of poly(∈‐caprolactone), ethylcellulose, and polystyrene microspheres, prepared by the solvent evaporation method, radiosterilized by γ‐irradiation, and stereotactically implanted in rat brain have been studied by routine staining and immunohistochemistry. During the first few days after implantation, a nonspecific astrocytic brain tissue reaction was observed along with a macrophagous‐microglial cell reaction typically found following any damage in the central nervous system, except in the presence of certain foreign body giant cells. Nine months into the experiment, microspheres appeared to be engulfed by histiocytic cells. The microsphere cluster was surrounded by a sheath composed of collagen and astrocytic cells. No necrosis was observed, suggesting the absence of toxicity. In some animals, however, an hydrocephalus developed as a result of obstruction of the medial ventricle by some microspheres. © 1994 John Wiley & Sons, Inc.
Production of spherical ZrO2‐Y2O3 and ZnO particles
Authors: Yaparpalvi R. , Loyalka S. K. , Tompson R. V. 
Published: May 2005

AbstractIn recent years substantial effort has been focused on the use of engineered ceramics for biomedical applications. To produce ceramic components with reliable and reproducible properties for such speciality applications, it is necessary to use high‐purity raw material powders with specific properties. Fine ceramic particles having specific shapes and sizes are also required for conducting biocompatibility experiments. This article reports on the laboratory scale production, in an aerosol reactor, of spherical, submicron zirconia (partially stabilized by yttria; ZrO2‐Y2O3) and zinc oxide (ZnO) particles by the thermal decomposition of mists generated from aqueous solutions of inorganic metal salt precursors. The particles produced were characterized by scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. © 1994 John Wiley & Sons, Inc.
Photochemical conjugation of mammalian cells to polymeric supports and membranes: A kinetic study
Authors: Bellobono I. R. , D'Ambrosio A. , Raimondi M. L. , Marangoni F. , Sirchia G. 
Published: May 2005

AbstractA commercial polyester acrylate prepolymer, to which a 2:3 wt/wt ratio of tripropyleneglycol diacrylate was added to increase photopolymerization rate, was employed as photochemical conjugating agent, through photografting. 1,2‐Diphenyl,2,2‐dimethoxyethanone was added as standard photoinitiator (7.0 wt/wt%), together with varying amounts (0.003–4.0 wt/wt%) of some proprietary photocatalytic systems, based on the following photocataiysts: m̈‐peroxobis [N,N′‐ethylene‐bis(salicylideneiminato)cobalt](III) (I), vanadium (V) triethoxide (II), and a synergic mixture of vanadium (V) tri‐t‐butoxide and tri‐i‐propoxide (III). A homogeneous suspension containing (10 ± 2) × 105 human thyroid follicular cells per milliliter of photochemically reacting medium was photografted, at a surface density of 6.5 ± 0.7 mg · cm −2 of diacrylate prepolymer mixture, onto polystyrene plates or onto commercial microfiltration and ultrafiltration membranes consisting of nonwoven cellulose tissues with known porosities varying between 5 and 30 m̈m and in photografted polyester acrylate‐based membranes with a cutoff of 50 ± 5 KD. Bioconjugation yields, as a function of photografting time, were measured gravimetrically and by multiple internal reflection IR spectroscopy. Three series of experiments were performed: (1) measurements of graft yields of the prepolymer, and of the parallel disappearance of double bonds, in the absence of mammalian cells; (2) the same as (1), in the presence of thyroid follicular cells; (3) the same as (2), but with the photoinitiating system formed by the standard photoinitiator alone, with no photocatalyst. Results show that if a suitable photocatalyst is not added, no practical conjugation is possible. An appropriate choice of the photocatalytic system and of its concentration allows reduction of irradiation times (e. g., by a factor of about 2 × 104 calculated as the mean lifetime ratio, between the uncatalyzed system and that with 0.1 wt% of [III]), thus minimizing cell inactivation and/or improving responsiveness to the bioassay. From this point of view, photoactivity of (III) is outstanding. The very small, but clearly perceptible, influence of polymeric support on bioconjugation is also commented upon. © 1994 John Wiley & Sons, Inc.
Strategy for developing microbeads applicable to islet xenotransplantation into a spotaneous diabetic NOD mouse
Authors: Iwata Hiroo , Takagi Tatsuya , Kobayashi Kazuo , Oka Takayuki , Tsuji Takayuki , Ito Fumiaki 
Published: May 2005

AbstractA bioartificial pancreas (BAP) created through the encapsulation of islets of Langerhans (islets) in a semipermeable membrane has been proposed as a promising approach to treating insulin‐dependent diabetes patients. A nonobese diabetic (NOD) mouse, which shares many features of human insulin‐dependent diabetes mellitus, is an ideal model for evaluating the function of BAP. However, the functions of BAPs that have been developed have been limited in NOD mice. We propose novel microbeads that can realize long‐term BAP function in NOD mice. The novel microbeads were composed of agarose and poly(styrene sulfonic acid) (PSSa) mixed gel. A polyion complex layer between PSSa and polycationic polybrene was formed on and just inside the microbead, and the microbead surfaces were further covered by polyanions to produce anionic surface charges. The islets in the novel microbeads were intraperitoneally implanted. Graft‐functioning periods were dependent on both PSSa concentration and the kinds of polyanion. Islets in the microbeads composed of 5% agarose and 5% PSSa, which had an outermost surface covered by carboxymethyl cellulose, produced normoglycemic periods of more than 60 days in all five recipients. Control mice receiving either transplants of unenclosed islets or islets in agarose microbeads showed normoglycemic periods of less than 12 days. We believe that agarose/PSSa microbeads are promising for producing semipermeable membranes that enable xenotransplantation of islets in spontaneous diabetes mellitus. © 1994 John Wiley & Sons, Inc.
Comparison of tissue factor and prostacyclin production by human umbilical vein endothelial cells on Dacron vascular prostheses and Dacron smooth films
Authors: Tunstall Ann , Eberhart Robert C. , Prager Morton D. 
Published: May 2005

AbstractThe functional capacity of human umbilical vein endothelial cells (HUVEC) grown on Dacron (polyethylene terephthalate; PET) vascular prosthetic material was compared with the function of cells on smooth surfaced PET, tissue culture polystyrene (TCPS), and Natrix‐coated TCPS. Prosthetic materials include two knitted fabrics (Bionit I and II) and two woven preparations (DeBakey Soft Woven and Extra Low Porosity). Two entities produced by HUVEC that influence blood coagulation were assessed: the procoagulant tissue factor (TF) and the anticoagulant prostacyclin (PGI2). Although TF activity was stimulated on all substrates by endotoxin (LPS), there was no difference among prostheses and no difference among smooth surface materials, but TF was reduced in cells on the prosthetic materials relative to those on smooth surface substrates. The reduced TF production by HUVEC on prosthetic material could be reversed by returning them to TCPS. In contrast, PGI2 production on prostheses was comparable to that on smooth surfaces for both stimulated and unstimulated cells. Stimulation with histamine (1 µM) gave a 2.4‐fold increase in PGI2 whereas mellitin (10 µg/ml) increased production 12.5‐fold. The differential response of HUVEC with regard to these two coagulation factors, one of which is secreted and the other membrane bound, may reflect the distorted shape of cells on fibers of the prosthesis. © 1994 John Wiley & Sons, Inc.
Inhibition of Staphylococcus adherence to biomaterials by extracellular slime of S. epidermidis RP12
Authors: Giridhar G. , Kreger A. S. , Myrvik Q. N. , Gristina A. G. 
Published: May 2005

AbstractAdherence of selected strains of coagulase‐negative staphylococci to various biomaterials, and the inhibition of their adherence by extracellular slime obtained from the RP12 strain of Staphylococcus epidermidis were studied in vitro. S. epidermidis RP12 adhered considerably more to polymethylmethacrylate (PMMA) discs than did the SP2 strain of S. hominis and the SE‐360 strain of S. hyicus. Strain RP12 was less adherent to titanium alloy, ultrahigh molecular weight polyethylene (UHMWPE), and Teflon discs than to PMMA discs. Exposure of PMMA discs to extracellular slime extracted from strain RP12 greatly reduced adherence of strain RP12, SP2, SE‐360, adn S. epidermidis RP‐62A. The active component(s) was present in the <10 kD mol wt fraction obtained by Amicon YM10 ultrafiltration of crude slime; heat treatment of the fraction did not affect its inhibitory activity. When the bacteria and RP12 slime fractions were added simultaneously to the PMMA discs, the >10 kD mol wt fraction of slime competitively inhibited adherence of strain RP12 to PMMA discs; in contrast, the <10 kD mol wt fraction enhanced adherence of strain RP12 to PMMA discs. © 1994 John Wiley & Sons, Inc.
Effect of bioactive ceramic composition and structure on in vitro behavior. III. Porous versus dense ceramics
Authors: Radin S. R. , Ducheyne P. 
Published: May 2005

AbstractIn vitro reaction kinetics of surface transformations of porous and dense bioactive ceramics were studied after immersion in simulated physiologic solution (SPS). Porous ceramics with identical macroporosity were commercially obtained: calcium carbonate marine coral (I‐CC), coralline HA (I‐HA), and a product, labeled as β‐tricalcium phosphate, which was partially transformed into β‐calcium pyrophosphate (I‐β‐CP). Previously studied dense ceramics were used for comparison: Ca‐deficient HA (CDHA), stoichiometric HA, both well and not well crystallized (wc and nwc s‐HA), β‐and α‐tricalcium phosphate (β‐ and α‐TCP). The induction time to precipitation increased as follows: CDHA, nec HA < wc HA, I‐HA < β‐TCP, I‐CC < I‐β‐CP. The reaction kinetics of ceramics with identical macroporosity varied substantially depending on composition, crystal structure, and ultrastructure. One of the porous ceramics, I‐β‐CP, showed an inhibiting effect on precipitation reactions. © 1994 John Wiley & Sons, Inc.
Interaction of chlorhexidine digluconate with and adsorption of chlorhexidine on hydroxyapatite
Authors: Misra D. N. 
Published: May 2005

AbstractIt is well known that chlorhexidine digluconate provides an effective microbicidal activity during oral rinsing, and therefore, it was considered worthwhile to investigate its interaction with hydroxyapatite on a fundamental level. The kinetics of uptake (or reaction) of the compound from aqueous solutions by synthetic hydroxyapatite was studied at 23°C for four time periods by monitoring its concentration. There was no uptake at low concentrations for any time period. The uptake curves for higher concentrations shifted towards the lower concentrations as the period increased and became more and more vertically oriented to the concentration axis. The concentrations of calcium ions increased, phosphate ions decreased and hydrogen ions decreased a little for a given period as the concentration of the compound was increased. All of these experimental facts can be qualitatively explained on the basis of the solubility considerations of hydroxyapatite and of chlorhexidine phosphate, the reaction product that slowly precipitates out of the solution. The needle‐shaped birefringent crystals of the phosphate salt are clearly visible in the apatite matrix under a microscope, and its refractive index and differential Fourier transform infrared spectra match almost exactly with those of a well‐characterized, synthesized phosphate salt. To explore the nature of interaction, the uptake of chlorhexidine base was studied from p‐dioxane and it is irreversible. The uptake is total below a threshold equilibrium concentration and constant above it. © 1994 John Wiley & Sons, Inc.
Study of the surface characteristics of magnetron‐sputter calcium phosphate coatings
Authors: Wolke J. G. C. , van Dijk K. , Schaeken H. G. , de Groot K. , Jansen J. A. 
Published: May 2005

AbstractPlasma‐sprayed hydroxylapatite coatings on metals such as titanium have been investigated for many years and have shown a good biocompatibility when implanted in bony tissues. Radiofrequency magnetron sputtering was used as an alternative method to deposit thin films of hydroxylapatite on titanium substrates. X‐ray diffraction demonstrated that the sputtered layer was crystalline with a preferred (001) crystallographic orientation with the C‐axis perpendicular to the substrate surface. Scanning electron microscopy showed that the deposited films had a uniform and dense structure. The calcium phosphate ratio varied between 1.5 and 2.0, as determined by energy‐dispersive X‐ray analysis. The in vitro dissolution appeared to be determined by the degree of the coating's crystallinity. © 1994 John Wiley & Sons, Inc.
Distinguishing wear and creep in clinically retrieved polyethylene inserts
Authors: McDonald Michael D. , Bloebaum Roy D. 
Published: May 2005

AbstractThere is an increasing awareness of the clinical problems associated with ultra‐high‐molecular‐weight polyethylene (UHMWPE) wear and failure in orthopedics. To better understand the reasons for wear and failure, methods were developed using polarized light microscopic analysis and backscattered electron (BSE) imaging with correlated elemental analysis to distinguish the contributions of wear, creep, and third‐body particulate. This study determined that microscopic metal particles (<10 μm) previously not observed with the stereomicroscope could be easily observed with the BSE technique. BSE imaging identified embedded metal in 5/5 of the tibial and 2/4 of the acetabular inserts, which were thought to be free of metal debris after stereoscopic examination. Correlated elemental analysis showed that the microscopic particles could be traced to the elements known to be present in the porous coatings of the retrieved uncemented implants. Creep was distinguished from wear in the total hip and total knee inserts by using polarized light microscopic techniques. Continued development of polarized light microscopic techniques applied in this investigation should assist biomaterials experts in the future to better distinguish wear and creep in retrieved clinical inserts. The correlated BSE and elemental analysis will assist in determining the roll of microscopic third‐body particular in wear and osteolysis in total joint replacement. © 1995 John Wiley & Sons, Inc.
Mixed‐metal fretting corrosion of Ti6Al4V and wrought cobalt alloy
Authors: Kawalec Jill S. , Brown Stanley A. , Payer Joe H. , Merritt Katharine 
Published: May 2005

AbstractCorrosion has been reported at the modular interfaces of total joint replacement implants, but with conflicting theories as to the cause of such damage. The modular design itself leaves the interface susceptible to galvanic, crevice, or fretting corrosion, or a combination of the three. The purpose of this study was to quantify the effect of material combination on fretting corrosion of orthopedic alloys. Each test specimen consisted of a two‐hole plate with spherical countersinks of a two cortical bone screws. The plates and screws were made of either Ti6Al4V or wrought cobalt–chromium–molybdenum (CCM), and were tested in all mixed‐metal and similar‐alloy combinations. Fretting corrosion experiments were conducted for 14 days in 10% calf serum, according to ASTM F897. Corrosion damage was evaluated by weight‐loss measurements, atomic absorption spectrophotometry and scanning electron microscopy analyses. The results indicated that Ti6Al4V suffered relatively severe damage when fretted against itself, as a result of adhesive galling. The extent of titanium damage was reduced considerably, however, when Ti6Al4V was fretted against wrought CCM. In contrast, there was essentially no difference in wrought CCM damage when the alloy was fretted against itself compared to fretting against Ti6Al4V. Finally, in similar‐alloy combinations, Ti6Al4V suffered more severe damage than wrought CCM. © 1995 John Wiley & Sons, Inc.
Effects of some technological aspects on the fatigue strength of a cementless hip stem
Authors: Viceconti Marco , Toni Aldo , Giunti Armando 
Published: May 2005

AbstractFour prototype cementless hip stems were tested following the ISO 7206 protocol for the assessment of the endurance properties and compared with a cast CrCoMo (ASTM F75) commercially available stem which was used as reference design. All the tested stems were similar in shape and size, but with some substantial differences. The first was made of forged Ti6Al4V alloy (ASTM F136). The second, made of the same material, featured a central hole intended to reduce the bending stiffness of the stem itself. The third was identical to the second but for a small tooling notch in one of the fillets of the hole. The fourth was similar to the first but had a coating of sintered titanium beads in the proximal part. All of these modifications were made to evaluate the effect of fatigue strength of intentional or unintentional features commonly found in commercial stems. The forged Ti6Al4V alloy was found to be substantially stronger than the cast ASTM F75 CrCoMo alloy. However, tooling notches or sintered coatings were found to dramatically reduce this strength. Thus, the Ti6Al4V alloy calls for an accurate design process, especially when complex shapes or sintered structures are required. © 1995 John Wiley & Sons, Inc.
Mechanical properties of xenogeneic small‐intestinal submucosa when used as an aortic graft in the dog
Authors: Hiles M. C. , Badylak S. F. , Lantz G. C. , Kokini K. , Geddes L. A. , Morff R. J. 
Published: May 2005

AbstractSmall‐intestinal submucosa (SIS) has been shown to induce tissue remodeling in vivo when used as a vascular graft. The present study investigated the physical and mechanical properties of remodeled aortic grafts derived from xenogeneic SIS material. Eight infrarenal aortic grafts were implanted in mongrel dogs. The grafts were explanted at 1 or 2 months and tested for compliance and hoop mechanical properties. The morphologic changes within the grafts were also characterized. The remodeling process produced graft structures which were significantly stronger than both the normal artery (P = .012) and the original SIS graft (P = .0001), and the compliance of these structures was one third that of normal artery and similar to the original SIS grafts. The remodeled grafts were > 10 times the thickness of the implanted SIS. Immunohistochemical analysis of remodeled tissues suggest that the SIS material was degraded and resorbed over time. The remodeling process transformed a material which was physically and mechanically quite different from normal aorta into a blood conduit which had the physical and mechanical properties needed to function in this mammalian arterial system. © 1995 John Wiley & Sons, Inc.
In vitro biocompatibility, mechanical properties, and corrosion resistance of TiZrNbTaPd and TiSnNbTaPd alloys
Authors: Ito Atsuo , Okazaki Yoshimitsu , Tateishi Tetsuya , Ito Yoshimasa 
Published: May 2005

AbstractThere is much discussion about the toxic effect of vanadium and aluminum contained in Ti6Al4V alloy for prosthetic implants. The goal of the present investigation was to develop new titanium alloys with sufficient mechanical properties using more biocompatible alloying elements: zirconium, tin, niobium, tantalum, and palladium. The relative growth rates of L929 and MC3T3‐E1 cells were significantly higher when cultured with the extraction of Ti10Zr8Nb2Ta0.2Pd or Ti15Zr4Nb2Ta0.2Pd alloys than when cultured with the extraction of Ti6Al4V ELI alloy. The tensile strength, elongation, and reduction of area for Ti15Sn4Nb2Ta0.2Pd alloy were 989 MPa, 14.4%, and 49.3%, respectively, surpassing Ti6Al4V ELI alloy (ASTM F13884); those for Ti15Zr4Nb2Ta0.2Pd alloy were 725 MPa, 23.6% and 54.9%, respectively. More than 15% addition of tin as well as zirconium deteriorated the tensile properties. Titanium release into a 5% hydrochloric acid solution from the new titanium alloys was 20–50 μg/cm2 per day, though that from Ti6Al4V ELI alloy was 1300 μg/cm2 per day. The optimum alloy compositions are Ti15Zr4Nb2Ta0.2Pd and Ti15Sn4Nb2Ta0.2Pd, judging from cytocompatibility, corrosion resistance, and mechanical properties. The former is characterized by its high level cytocompatibility and corrosion resistance, while the latter is characterized by mechanical properties. © 1995 John Wiley & Sons, Inc.
Anchorage of TiO2‐blasted, HA‐coated, and machined implants: An experimental study with rabbits
Authors: Gotfredson Klaus , Wennerberg Ann , Johansson Carina , Skovgaard Lene Teil , Hjørting‐Hansen Erik 
Published: May 2005

AbstractThe purpose of this study was to evaluate the histometrical and biomechanical anchorage of TiO2‐blasted implants and TiO2‐blasted implants coated with hydroxyapatite. The control implants were machined. Twenty‐six rabbits had a total of 156 implants placed in the proximal part of the tibia. Each rabbit had a machined, a TiO2‐blasted, and a TiO2‐blasted, HA‐coated implant placed in each tibia. After a healing period of 3 and 12 weeks, respectively, the implants placed in the right tibia were used for removal torque test, and the implants placed in the left tibia were used for histomorphometrical measurements. Preoperatively, implants from the same batches were examined topographically with a TopScan 3D system. The TiO2‐blasted implants demonstrated significantly higher removal torque values than the machined implants, and they also had a significantly more irregular surface. Furthermore, significantly higher bone‐to‐implant contact length fractions were measured adjacent to the TiO2‐blasted implants in contrast to the machined implants. The advantages of a TiO2‐blasted surface were more pronounced after 3 weeks than after 12 weeks. The results demonstrated that it was possible to influence the anchorage of implants by altering the surface structure morphology. The new method with TiO2 blasting on the titanium surface improves the anchorage o fimplants but is not yet practicable for HA coating. © 1995 John Wiley & Sons, Inc.