bluuebunny/crossref_metadata_2025 huggingface dataset:
Tissues at the surface of the new composite material titanium/glass‐ceramic for replacement of bone and teeth
Authors: Müller‐Mai Ch. , Schmitz H.‐J. , Strunz V. , Fuhrmann G. , Fritz Th. , Gross U. M.
Published: December 2004

A new composite implant material titanium/glass‐ceramic was tested in rabbits using light microscopy, histomorphometry, and biomechanical testing methods. Two rabbit implant models were used. The first premolar tooth was replaced and cylinders inserted into the trabecular bone of the distal femur below the patella sliding plane. There was bone bonding to the glassceramic component and additional mechanical interlocking, due to bone ingrowth between the titanium matrix into secondary pores. This was proved by measuring the tensile strength at the interface of the new composite material which was in the same range as compared to pure glassceramic implants. In tooth replacement there was a tight attachment of gingival epithelium and stroma to composite titanium/glass‐ceramic. These results are of particular clinical interest: physicochemical bone bonding and additional mechanical interlocking result in a resistance of the implant material against shear and tensile loads at the interface. Therefore this new composite material should be suitable for further load‐bearing applications.
A histomorphometric comparison of the muscular tissue reactions to high‐density polyethylene in rats and rabbits
Authors: Christel P. , Meunier A.
Published: December 2004

In order to bring quantitative elements into the rational selection of animal species for the evaluation of in vivo compatibility of biomaterials, a comparison between the muscular tissue response of rats and rabbits was made using quantitative histomorphometry. The experimental model was based on the quantification of the tissue reaction to specimens made of ultra‐high‐density‐polyethylene (UHDPE) implanted in the paravertebral muscles, according to ASTM F‐469 standard. The tissue reaction was evaluated by digitization of both the encapsulating membrane contours and the different cells types located within it. In each animal species, the cell distribution from the interface exhibited an asymetric bell‐shape curve with a maximum close to the interface, corresponding to a three‐parameter statistical model. The membrane thikness, a fibrocyte‐related parameter, was larger in the rabbit, but its time‐course was identical in each species, showing a late and significant increase. Few differences were observed for most cell types due to the low level of foreign‐body‐reaction induced by HDPE implants. Although there were interspecies differences for fibrocytes and, to a lesser extent, macrophages, between 2 and 8 weeks, weeks, there was no statistical differences for any of the computed parameters either at 2 weeks or between 26‐week rats and 52‐week rabbits. The quantitative histomorphometry picked up differences between close tissue responses, whereas the qualitative observation was unable to demonstrate distinguishing differences between rats and rabbits.
Correlation between mesh size and equilibrium degree of swelling of polymeric networks
Authors: Canal Tiziana , Peppas Nikolaos A.
Published: December 2004

A correlation is established between the mesh size of a swollen cross‐linked network and its equilibrium polymer volume fraction, for hydrogels isothermally swollen up to semidilute, dilute, or concentrated conditions. The exponent of this correlation decreases as the water concentration of the hydrogel decreases. Experimental results with hydrogels of poly(vinyl alcohol) and poly(2‐hydroxy ethyl methacrylate) are used to verify the new scaling laws.
Effect of liposomes on hamster oral mucosa
Authors: Foong W. C. , Harsanyi B. B. , Mezei M.
Published: December 2004

The histologic reaction to topically applied or intramucosally injected DPPC/chol (2:1 molar ratio) liposomes was investigated. No reaction to liposomes was observed 4 days after daily topical application. However, a mild focal immune type inflammatory reaction was observed after 21 days topical treatment. Intramucosal injection of liposome produced no irritation but a macrophage reaction limited to the injection site, which was followed by healing and complete tissue regeneration.
Evaluation of metal implants coated with several types of ceramics as biomaterials
Authors: Hayashi K. , Matsuguchi N. , Uenoyama K. , Kanemaru T. , Sugioka Y.
Published: December 2004

The in vivo biocompatibility of metals coated with several different types of ceramics [alumina (α‐Al2O3), titanium oxide (TiO2), titanium nitride (TiN), and hydroxyapatite (HAP)] was investigated. These composites had been devised for the purpose of incorporation into the stem of a total hip prosthesis. The materials were inserted into the mid‐diaphyseal region of the femurs of adult dogs, and follow‐up quantitative histological comparisons were performed for a period of up to 96 weeks. HAP‐coated composites showed the best biocompatibility.
Acute histopathological response to a new biodegradable polypeptidic polymer for implantable drug delivery system
Authors: Lescure F. , Gurny R. , Doelker E. , Pelaprat M. L. , Bichon D. , Anderson J. M.
Published: December 2004

This article deals with the in vivo evaluation of a new class of synthetic polypeptides, the poly[(tert‐butyloxycarbonylmethyl) glutamates], POMEG, as an injectable or implantable drug delivery system. Three different polymers, varying in their degree of esterification, were extruded either with or without progesterone, and finally implanted in rats up to 14 days. Histologic evaluation of the implant sites show evidence of the good biocompatibility of these polymers. In addition, the description of their in vivo behavior, based on microscopic observation of the implanted POMEG rods, enables one to appreciate their potential as a drug delivery system for short‐ or long‐term therapy.
Toxic effects of aldehydes released from fixed pericardium on bovine aortic endothelial cells
Authors: Eybl E. , Griesmacher A. , Grimm M. , Wolner E.
Published: December 2004

Glutaraldehyde (GA) and formaldehyde (FA) were shown to be released from 1 cm2 fixed pericard patches into 2‐mL storage solutions after three 2‐min washings in concentrations of about 1 mg/L. The cytotoxicity of these aldehyde concentrations on bovine aortic endothelial cells (BAECs) was evaluated in vitro, by proliferation capacity, cellular ATP content, PGI2 release and cyclic AMP synthesis. Continuous incubation of BAECs with GA > 0.1 mg/L and FA > 0.5 mg/L resulted in a significantly inhibited proliferation and in an increase of the intracellular Ca2+ triggered parameters, PGI2 and cyclic AMP, up to three fold. This strongly suggests an aldehyde‐induced inhibition of the plasmamembrane bound Ca2+‐ATPase, an enzyme which normally maintains low intracellular Ca2+‐level. From these findings there is evidence that aldehydes released from bioprosthetic valve tissue may contribute to the lack of endothelial cell coverage in human implants.
Repair of experimental arteriotomy in rabbit aorta using a new resorbable elastin—fibrin biomaterial
Authors: Lefebvre F. , Drouillet F. , de Larclause A. M. Savin , Aprahamian M. , Midy D. , Bordenave L. , Rabaud M.
Published: December 2004

A new artificial connective matrix which results from two reactions of fibrinogen and fibronectin on elastin was used to obturate a slit made in the abdominal aorta of rabbit. The so‐called Elastin—Fibrin biomaterial behaved as a scaffold through which all the different structures were restored to their former condition. At 3 months, the material had disappeared and no thrombus, no inflammation or reject had been detected.
Establishment of a neovascular bed in a collegen‐impregnated polyurethane sponge
Authors: Lipsky M. H. , Lamberton P.
Published: December 2004

A technique for promoting vascularization of a polyurethane sponge is demonstrated in the present study. Collagen‐impregnated polyurethane sponges (Hypol, 2002) Foamable Hydrophilic Prepolymer (FHP) were implanted in the femoral fossa of rats for 1 day to 6 weeks. The ligated femoral artery/vein was pulled through the sponges to facilitate more complete neovascularization. Light‐microscopic evaluation of the implanted sponges revealed that significant vascularization had occurred by the seventh day of implantation, and was maximal by the fourth to sixth week. Sponges containing collagen had a more thorough vascularization process than sponges without collagen, perhaps due to a more uniform pore size as demonstrated by scanning EM. Time course studies suggested that the artery/vein pull‐through enhanced the development of the neovascularization process in the center of the sponges. We conclude that significant vascular tissue in‐growth can be developed in polyurethane sponges and that both collagen and centrally placed blood vessels help promote the vascularization process. Potential applications could extend to a variety of bioartificial systems including endocrine or hepatic transplantation, softtissue prosthetic materials, bone grafts, or drug delivery systems. Further studies would be useful in providing additional information on the factors promoting neovascularization, and on the potential applications of this methodology using the present or similar biomaterials.
Adhesive bone cement both to bone and metals: 4‐META in MMA initiated with tri‐n‐butyl borane
Authors: Ishihara Kazuhiko , Nakabayashi Nobuo
Published: December 2004

In order to develop a new bone cement which is expected to prevent loosening of a prosthesis by better adhesion, the cement composed of 4‐methacryloyloxyethyl trimellitate anhydride (4‐META) and methyl methacrylate (MMA) as monomers and tri‐n‐butyl borane (TBB) as an initiator was evaluated. The tensile bond strength between bone and metals adhered with 4‐META/MMA‐TBB cement was above 7 MPa. The values were higher than that with conventional bone cement (1 MPa) or MMA‐TBB cement (2 MPa). Therefore, 4‐META was effective for improving adhesion. When cohesive failure of the bone was observed with the scanning electron micrography after the tensile test, fracture occurred on the bone side below the interface between the bone and the 4‐META/MMA‐TBB cement. This result showed that the cement adhered tightly to both the bone and metals. Thus, it is concluded that the 4‐META/MMA‐TBB cement is useful as an adhesive bone cement.
Mechanical properties of bone after implantation of apatite–wollastonite containing glass ceramic–fibrin mixture
Authors: Ono Kozo , Yamamuro Takao , Nakamura Takashi , Kokubo Tadashi
Published: December 2004

Mechanical properties of bone implanted with a mixture of apatite–wollastonite containing glass ceramic (A–W.GC) granules and fibrin were examined by compression testing. A 1:1 mixture of A–W.GC granules and fibrin (Group 1), 1:4 mixture of A–W.GC granules and fibrin (Group 2), and 1:1 mixture of hydroxyapatite (HA) granules and fibrin (Group 3) were implanted in the distal femoral metaphyses of rabbits. Histomorphometric analysis suggested that A–W.GC has a greater osteoconductive potential than HA. Trabeculalike structures were observed 24 weeks after the operation in all groups but were most notable in Group 2. Twenty‐four weeks after the operation, in Groups 1 and 3, the compressive strength and compressive stiffness were higher than that of normal cancellous bone, and the fracture toughness was comparable with that of normal cancellous bone. In Group 2, all three values were similar to those of normal cancellous bone.

Implantation of A–W.GC granules at a low density induces the formation of bone tissue which is similar to normal bone in both mechanical properties and morphology.
Modified ethoxyethyl cyanoacrylate for therapeutic embolization of arteriovenous malformation
Authors: Tseng Yin‐Chao , Hyon Suong‐Hyu , Ikada Yoshito , Taki Waro , Uno Akira , Yonekawa Yasuhiro
Published: December 2004

Aiming at alleviating the problems of using 2‐cyanoacrylates as a material for therapeutic embolization, this experiment made some physical modifications by mixing contrast media. It was found that the physicochemical properties of 2‐cyanoacrylates can be altered by changing the concentration and the composition of the contrast media added. A 50 wt% cyanoacrylate–50 wt% contrast medium mixture has enough radiopacity for the practical requirement for embolization. A mixture of 50 wt% (ethoxyethyl cyanoacrylate‐5 wt% lactide/ ϵ‐caprolactone copolymer), 25 wt% lipiodol and 25 wt% tetrafluorodibro‐moethane provides a viscosity of 13.8 cP, a bonding strength of 14.9 kg/cm2, a set time of 6 s, and a spreading in canine blood of 33 mm. It was concluded that the mixture is much more satisfactory than the conventional cyanoacrylates as an embolus material in vitro. The results obtained by in vivo experiments and clinical trials so far suggest that the mixture is very promising as a material for embolization.
Series shunt evaluation of polyurethane vascular graft materials in chronically AV‐shunted canines
Authors: McCoy Timothy J. , Wabers Hugh D. , Cooper Stuart L.
Published: December 2004

Well characterized, laboratory‐synthesized polymeric materials which have been extensively tested for biocompatibility via initial platelet and protein deposition in an acute ex vivo canine model were placed as interpositional series shunts in canines with chronically implanted iliac arteriovenous shunts ex vivo. Platelet deposition was measured on a base polyurethane block copolymer, a sulfonated ionic derivative, an alkyl grafted (C18) derivative, Biomer, polyethylene, and polydimethylsiloxane for 24 h using radiolabeled platelets. Platelet survival and in vitro aggregation were determined to investigate the effects of the shunting pprocedure on experimental animals. The viability of adopting a chronic arteriovenous (iliac) shunted canine model for use with series shunts to evaluate polyurethanes having applications as materials in vascular graft construction was investigated and the results compared with acute model data.
Adsorption of plasma proteins and adhesion of platelets onto novel polyetherurethaneureas—relationship between denaturation of adsorbed proteins and platelet adhesion
Authors: Ito Y. , Sisido M. , Imanishi Y.
Published: December 2004

Novel polyetherurethaneureas which have been synthesized by the present authors were chosen for the substrate polymers, on which adhesion of platelets was investigated. The number of adhered platelets and the amount of serotonin released from platelets adhered on the polymers and the protein‐coated polymers were determined by radioisotope method. Both of them were ehanced with increasing content of urea linkages in the polyetherurethaneureas. The platelet adhesion was discussed in terms of the denaturation of plasma proteins upon adsorption, which was determined by Fourier‐transform infrared spectroscopy. With increasing degree of protein denaturation, the platelet adhesion and the serotonin release were enhanced. This relationship was particularly evident in the case of albumin adsorption. It was shown that the surface properties of substrate polymers affect the protein adsorption, which in turn influences the adhesion of platelets.
Analysis of A · W glass‐ceramic surface by micro‐beam X‐ray diffraction
Authors: Kitsugi Toshiaki , Yamamuro Takao , Kokubo Tadashi
Published: December 2004

The purpose of this study is to examine the formation of hydroxyapatite on the surface of glass‐ceramics (chemical composition: SiO2, 34.2; P2O5, 16.3; CaO, 44.9; MgO, 4.6; CaF2, 0.5 in weight ratio). Two experiments were performed. In the first experiment, plates (2 × 25 × 25 mm) of glass‐ceramics containing apatite‐wollastonite (designated A · W–GC) were used. In the second experiment, plates (15 × 10 × 2 mm) of A · W–GC and its parent glass (designated G) were used. In each experiment, two paired specimens of identical material, one tied with silk thread, the other not tied, were implanted subcutaneously into rats. In both experiments, bonding to each other of both tied and untied specimens was observed one month after implantation. A pattern resembling hydroxyapatite was identified on the detached surface of the bonded A · W–GC by micro‐beam x‐ray diffraction. The weak crystalline pattern was also observed on the detached surface of bonded G samples. Analysis of the interface by SEM‐EPMA showed that a calcium‐phosphorus rich layer formed between the two bonded surfaces in both experiments. It is suggested that the bonding between the two materials was formed by the calcium‐phosphorus rich layer, and that the calcium‐phosphorus rich layer is virtually identical to hydroxyapatite.
Tissue/biomaterial interface characteristics of four elastomers. A transmission electron microscopical study
Authors: Bakker D. , van Blitterswijk C. A. , Hesseling S. C. , Daems W. Th. , Grote J. J.
Published: December 2004

The tissue/biomaterial interface reactions of four elastomers—selected as candidates for scaffolding for tympanic membrane tissue in a total alloplastic middle ear prosthesis—were studied at the electron microscopical level after implantation in the rat middle ear. Time‐dependent changes in the phagocyte/polymer interface suggested degradation of porous implants made of Estane polyether urethane, polypropylene oxide, and a poly(ethylene oxide hydantoin) and poly(tetramethylene terephthalate) segmented polyether polyester copolymer (HPOE/PBT copolymer), but not of dense Silastic silicone rubber implants. Silastic was always encapsulated in fibrous tissue. Contact between fibrous tissue and HPOE/PBT copolymer or Estane was established in the third month, but fibrous tissue was never seen close to polypropylene oxide. Bone made contact only with Estane and HPOE/PBT copolymer implants. The bone/copolymer interface showed an electron‐dense layer morphologically similar to that seen between bone and hydroxyapatite ceramic, suggesting that with respect to bone HPOE/PBT copolymer behaves like a bioactive implant material. The electron‐dense layer was absent at the bone/Estane interface. Estane and especially HPOE/PBT copolymer seem to be suitable as alloplastic tympanic membrane because of their interface behavior with respect to fibrous tissue and bone.
Tissue response to percutaneous implants in rabbits
Authors: Jansen J. A. , van Der Waerden J. P. C. M. , van der Lubbe H. B. M. , de Groot K.
Published: December 2004

This study reports on certain aspects of wound‐healing around percutaneous implants. Plasma‐sprayed and dense hydroxylapatite, titanium, and carbon test implants were inserted into the tibia and the cranium of 12 rabbits. Four and 8 months after insertion, the animals were sacrificed and the implants with their surrounding tissues were processed histologically. Light‐ and transmission electron microscopic investigations were performed. It is found that direct and indirect boneanchoring favors the longevity of percutaneous implants. No differences in tissue reaction between the various implant materials were observed.
Surface modification of biomaterials through noble metal ion implantation
Authors: Buchanan R. A. , Lee In‐Seop , Williams J. M.
Published: December 2004

Studies are described involving effects of noble‐metal ion implantation on corrosion inhibition and charge‐injection capabilities of surgical Ti‐6Al‐4V alloy. A major factor linked to excellent long‐term biological performance is resistance to metal‐ion release to tissues. The elements most resistant to corrosion in aqueous solutions are the noble metals. Disadvantages include expense and general inadequacy of mechanical properties. However, if small quantities can be used to surface‐modify a surgical device in the last stage of manufacture, that device could possess an optimum combination of environmental integrity, biological response, mechanical properties, and charge‐injection capability at miniumum expense. Results for ion‐implanted Ir are presented. Iridium has been described as the most corrosion‐resistant element known, and its activated oxide as having the highest charge‐injection capability of any material known. Ti‐6Al‐4V samples, ion implanted with 2.5 and 5.0 atomic % peak‐maximum concentrations of Ir, were subjected to corrosion treatments to enrich the surface with Ir. Corrosion potential and cyclic voltammetry measurements indicated enrichment in H2SO4, and continued enrichment in isotonic saline, with corrosion potentials approaching that of pure Ir, and charge densities in isotonic saline exceeding that of pure Ir for the 5.0% peak‐max Ir implanted material. X‐ray photoelectron spectroscopy confirmed the high levels of Ir surface enrichment.
Bactericidal properties of a titanium‐peroxy gel obtained from metallic titanium and hydrogen peroxide
Authors: Tengvall P. , Hörnsten E. G. , Elwing H. , Lundström I.
Published: December 2004

A stable titanium‐peroxy‐radical complex is formed when metallic titanium interacts with hydrogen peroxide. The radical appears as one component in an aqueous gel formed when excess peroxides have been (catalytically) decomposed. The interaction between titanium and hydrogen peroxide may be of importance also in vivo during an inflammatory response at the implant. We report in this paper on the bactericidal effects of the titanium gel in the lacto‐ and myeloperoxidase–halogen systems. Escherichia coli viable count was used to evaluate the bactericidal properties of the gel and of H2O2 for comparison. The gel had only small or no toxic properties at high dilutions. Higher concentrations of the gel had bactericidal properties similar to those of H2O2. The results indicate that at physiological pH, the decomposition products of the gel are titanium hydroxide (Ti(IV)(OH−)4) and hydrogen peroxide (H2O2). It was found that the gel probably oxidizes glutathione directly in contrast to H2O2, which needs a peroxidase to do so. A model for the interaction between titanium and hydrogen peroxide is suggested. Its consequences for the properties of titanium in vivo are also discussed.
Ca, P‐rich layer formed on high‐strength bioactive glass‐ceramic A‐W
Authors: Kokubo T. , Ito S. , Huang Z. T. , Hayashi T. , Sakka S. , Kitsugi T. , Yamamuro T.
Published: December 2004

Glass‐ceramic A‐W, containing crystalline apatite and wollastonite in a MgOCaOSiO2 glassy matrix shows high bioactivity as well as high mechanical strength, but other ceramics containing the same kinds of crystalline phases in different glassy matrices do not show the same bioactivity. In order to investigate the bone‐bonding mechanism of this type of glass‐ceramic, surface structural changes of the glass‐ceramics after exposure to simulated body fluid were analyzed with various techniques. A solution with ion concentrations which are almost equal to those of the human blood plasma was used as the simulated body fluid, instead of Tris‐buffer solution hitherto used. For analyzing the surface structural changes, thin‐film x‐ray diffraction was used in addition to conventional techniques. It was found that a bioactive glass‐ceramic forms a Ca, P‐rich layer on its surface in the fluid but nonbioactive ones do not, and that the Ca, P‐rich layer consists of carbonate‐containing hydroxyapatite of small crystallites and/or defective structure. These findings were common to those of Bioglass‐type glasses. So, we conclude that the essential condition for glass and glass‐ceramic to bond to bone is the formation of the surface apatite layer in the body environment but it is not essential to contain apatite within the material. Bioactivity of glass and glass‐ceramic can be evaluated in vitro by examining the formation of the surface apatite layer in the simulated body fluid described above.
Effect of alternative crosslinking methods on the low strain rate viscoelastic properties of bovine pericardial bioprosthetic material
Authors: Pereira Christoper A. , Michael Lee R. J. , Haberer Sean A.
Published: December 2004

Early failures of bovine pericardial heart valves have been due to leaflet perforation/tearing and calcification. Since glutaraldehyde fixation has been shown to produce marked changes in leaflet mechanics and has been linked to the development of calcification, alternative crosslinking techniques have been suggested as means to overcome these obstacles. We have examined the low strain rate viscoelastic behavior of bovine pericardium: (1) fresh; (2) chemically treated with glutaraldehyde, cyanimide, or polyglycidyl ether; or (3) physically treated by freeze‐drying or heat‐drying. Shrinkage temperature tests were conducted to assess intrahelical crosslinking. Polyglycidyl ether and glutaraldehyde both produced substantial crosslinking, with the shrinkage temperature rising above 80°C. Mechanical changes were nearly equivalent, both showing decreased stress relaxation and increased extensibility consistent with intrahelical crosslinking and shrinkage during fixation. Cyanimide, known to crosslink pure collagen materials, showed no evidence of crosslinking intact tissue. Heat‐drying, also effective in pure collagen preparations, produced an increase in UTS and tissue modulus, but otherwise left the tissue unchanged. Freeze‐drying had no mechanical effect, and therefore provides an attractive means for the storage of connective tissues for later mechanical testing.
Macroporous calcium phosphate ceramic for long bone surgery in humans and dogs. Clinical and histological study
Authors: Daculsi G. , Passuti N. , Martin S. , Deudon C. , Legeros R. Z. , Raher S.
Published: December 2004

Our previous studies reported the performance of Macroporous Biphasic Calcium Phosphate (MBCP) in spine fusion. In the present study, this material was used in block forms in selected patients with tumoral resection in long bone. Two cases were chosen with large benign bone tumors. Clinical and radiographic assessments, CT scans, and NMR were performed after 16 months, and in one case control biopsies were taken. In order to understand the kinetic process of biodegradation of the MBCP blocks and bone formation at the expense of the ceramics, an experimental study in surgicaly created bond defects in canine femoral cortices was made. The MBCP blocks recovered after implantation period from 2 to 18 weeks were analyzed using histological, stereological, ultrastructural, electron microprobe, and IR spectroscopy analyses. This study demonstrated the efficiency of MBCP blocks for filling pathological defects in human long bone. The biointegration process of the MBCP blocks was due to a partial dissolution of the ceramics crystals (b‐TCP content) by multinucleated cells. Simultaneously, bone ingrowth at the expense of the ceramic is observed. The new bone formation inside the MBCP macropores and in the spaces between the blocks, involved the formation of a new cortical bone on the outer part, and a trabecularlike bone with bone marrow in the inner part of the implant. The biological resorption of the MBCP ceramic decreased after 1 month implantation in dog, due to the protective role of the newly formed lamellar bone on the surface and in the core of the ceramics.
The biocompatibility of hydroxyapatite ceramic: A study of retrieved human middle ear implants
Authors: van Blitterswijk C. A. , Hesseling S. C. , Grote J. J. , Koerten H. K. , de Groot K.
Published: December 2004

The biocompatibility of 11 hydroxyapatite auditory canal‐wall prostheses and 4 hydroxyapatite incus prostheses implanted for 4 to 40 months was evaluated by light microscopy, scanning electron microscopy, transmission electron microscopy, and Röntgen microanalysis. These 15 prostheses representing 4% of 375 prostheses, had been removed because of unresolved chronic middle ear infection, residual cholesteatoma, or poor fit. The findings confirmed earlier reports on the biocompatibility of hydroxyapatite in vitro, in animals, and in man. An electron‐dense layer was found at the interface with bone and fibrous tissue, and a firm bond between the ceramic and bone at the hydroxyapatite ceramic/bone interface developed. Macropores became filled with bone and fibrous tissue, and the tissue in the individual pores was interconnected. Furthermore the incus prostheses were covered with an epithelium similar to that found in the human middle ear. Findings diverging from those made in other studies were the relatively large amount of exudate in the pores, an apparent increase of degradation during infection, and the accumulation of trace elements in one of the canal‐wall prostheses. In all likelihood these three phenomena may be attributed to the unfavorable conditions to which these prostheses were exposed during implantation.
X‐ray diffraction studies on plasma‐sprayed calcium phosphate‐coated implants
Authors: Koch B. , Wolke J. G. C. , de Groot K.
Published: December 2004

Calcium phosphate coatings on steel, obtained by the plasma‐spray technique, were examined by x‐ray diffraction in order to get some information on their crystallographic structure and crystallinity. Surface roughness values were also determined. These coatings are of interest for hip‐prosthesis materials in particular.
The behavior of alloplastic tympanic membranes in Staphylococcus aureus‐induced middle ear infection. I. Quantitative biocompatibility evaluation
Authors: Bakker D. , van Blitterswijk C. A. , Hesseling S. C. , Th. Daems W. , Kuijpers W. , Grote J. J.
Published: December 2004

The biocompatibility of dense Silastic implants and porous implants made of Estane 5714 F1 polyether urethane, polypropylene oxide, and an HPOE/PBT segmented polyether polyester copolymer was evaluated during an induced Staphylococcus aureus middle ear infection.

The middle ear response to infection seemed not to be affected by the presence of implants made of either of the polymers. Light microscopical morphometry and transmission electron microscopy showed degradation of the porous implants under study, but not of Silastic implants, which were invariably surrounded by a fibrous capsule. This finding, combined with the degree of porous implant degradation, the composition of the tissues surrounding the implants, and the tissue/biomaterial interface reactions are consistent with the results obtained in the noninfected middle ear. Round‐cell infiltrates however, were predominantly associated with implants made of polypropylene oxide and HPOE/PBT copolymer; while the presence of (phagocytosed) microbial debris was associated with copolymer.

The present findings indicate that with respect to implant behavior in infected surroundings Estane is the best porous material, whereas the behavior of Silastic implants did not deviate from that in noninfected ears.
Acrylated phosphonate esters containing 1,3‐dioxane and 1,3‐dioxolane moieties as adhesion‐promoting agents for dentin and hard tissues, I
Authors: Cabasso Israel , Sahni Suresh
Published: December 2004

Novel acrylated phosphonate esters containing 1,3‐dioxane and 1,3‐dioxolane moieties derived from polyols such as glycerol, D‐mannitol, D‐sorbitol, pentaerythritol, and dipentaerythritol have been evaluated in vitro for their role as adhesion‐promoting agents in composites employed for restorative dentistry. Some of the acrylated phosphonate esters have been found to promote strong bonding to dentin; the dipentaerythritol derivative exhibits a bond strength of approximately 960 psi (7 MPa) which compares favorably to commercial dentin adhesive systems. The bonding agents appear to act in multifunctional ways: the phosphonate group of the monomer chelates the calcium ions of hydroxyapatite at the dentin surface, ethereal oxygen atoms of 1,3‐dioxolane or 1,3‐dioxane moieties interact with the proteinaceous content of collagen, and the methacrylic fragment copolymerizes concomitantly with the other comonomers of the restorative composite material. Methods of preparing radiopaque adhesionpromoting acrylated phosphonates are also discussed.
Solutions able to reproduce in vivo surface‐structure changes in bioactive glass‐ceramic A‐W3
Authors: Kokubo T. , Kushitani H. , Sakka S. , Kitsugi T. , Yamamuro T.
Published: December 2004

High‐strength bioactive glass‐ceramic A‐W was soaked in various acellular aqueous solutions different in ion concentrations and pH. After soaking for 7 and 30 days, surface structural changes of the glassceramic were investigated by means of Fourier transform infrared reflection spectroscopy, thin‐film x‐ray diffraction, and scanning electronmicroscopic observation, in comparison with in vivo surface structural changes. So‐called Tris buffer solution, pure water buffered with trishydroxymethyl‐aminomethane, which had been used by various workers as a “simulated body fluid,” did not reproduce the in vivo surface structural changes, i.e., apatite formation on the surface. A solution, ion concentrations and pH of which are almost equal to those of the human blood plasma—i.e., Na+ 142.0, K+ 5.0, Mg2+ 1.5, Ca2+ 2.5, Cl− 148.8, HCO3− 4.2 and PO42− 1.0 mM and buffered at pH 7.25 with the trishydroxymethylaminomethane–most precisely reproduced in vivo surface structure change. This shows that careful selection of simulated body fluid is required for in vitro experiments. The results also support the concept that the apatite phase on the surface of glass‐ceramic A‐W is formed by a chemical reaction of the glass‐ceramic with the Ca2+, HPO42−, and OH− ions in the body fluid.
Preliminary characterization of bioresorbable and nonresorbable synthetic fibers for the repair of soft tissue injuries
Authors: Shieh Sheu‐Jane , Zimmerman Mark C. , Parsons J. Russell
Published: December 2004

Preliminary characterizations of two new synthetic fibers were performed to determine their potentials for use in soft tissue scaffolding devices. A slowly bioresorbing random copolymer of dimethyltrimethylene carbonate (DMTMC) and trimethylene carbonate (TMC) was the first fiber evaluated. The second was a nonresorbable high‐strength synthetic fiber of highly oriented polyethylene. Their in vitro mechanical behavior was evaluated by loading fibers in uniaxial tension to determine mechanical properties in dry and wet (saline) environments. The polyethylene fiber had a dry strength of approximately 2.0 GPa, an ultimate strain of 3 to 4%, a tangent modulus of 57 GPa, and was not affected by the saline environment. The bioresorbable fiber had a dry strength of approximately 500 MPa, an ultimate strain of 35%, and tangent modulus of 5.4 GPa. The in vitro resorption of the bioresorbable fibers produced a 15% loss in strength over a 10‐week period. In vitro cell‐fiber compatibility studies were conducted to assay material biocompatibility and fiber substrate efficacy. Fibroblasts proliferated and migrated on both the polyethylene and bioresorbable fibers at rates similar to those previously found for other compatible fibers, thus demonstrating the new materials to be similar in their in vitro biocompatibility profiles. Morphological assessment with SEM also confirmed that these materials were suitable substrates for cell attachment. A rabbit Achilles tendon repair model using oriented polyethylene or bioresorbable fiber tows was evaluated after 12 and 26 weeks of implantation. The mechanical performances of both types of tendon repairs were similar to those found in previous studies using carbon or PET fibers. The polyethylene fibers elicited a low‐grade chronic inflammatory tissue response. The bioresorbable fibers were still intact at 26 weeks and remained relatively inert in the host tissue, eliciting a minimal foreign body response.
Difference in tissue response to nitrogen‐ion‐implanted titanium and c.p. titanium in the abdominal wall of the rat
Authors: Röstlund Tord , Thomsen Peter , Bjursten Lars Magnus , Ericson Lars E.
Published: December 2004

Ion implantation modifies the surface properties of different materials. We have compared the biological properties of titanium implanted with nitrogen with those of pure titanium. Implants were inserted in the abdominal wall of rats. The implants with surrounding tissue were excised after 1 and 6 weeks, and embedded in epoxy resin. The bulk metal was removed electrochemically and the tissue cut for light and electron microscopy. Using this technique the implant surface, formed by a thin oxide layer, remains and appears in sections as a dense line. After 1 week both types of implants were surrounded by a fluid space containing proteins and scattered macrophages but few polymorphonuclear granulocytes. The fluid space was wider around ionimplanted titanium (52 ± 22 μm) than around pure titanium implants (15 ± 3 μm). After 6 weeks the fluid space had largely disappeared around both type of implants. Around pure titanium implants macrophages and fibroblasts, quantified in 1‐μm‐thick sections in the light microscope, were present in about the same concentration in the inner tissue zone (within 25 μm from the implant surface). Around ion‐implanted titanium macrophages predominated in the inner zone and multinuclear giant cells were present in almost all sections. Around both type of implants fibroblasts increased and macrophages decreased with increasing distance from the surface. In the electron microscope macrophages close to the surface of pure titanium were of small size and had an ultrastructure indicating a low activity. Macrophages close to ion‐implanted titanium were large and had an active appearance as indicated by the presence of large amounts of endoplasmic reticulum and large Golgi areas in the cytoplasm. Our observations indicate that modification of the surface properties of titanium implants by ion implantation changes the biological properties.
Study of the effect of the surface state on the cytocompatibility of a Co‐Cr alloy using human osteoblasts and fibroblasts
Authors: Naji Abdessamad , Harmand Marie‐Françoise
Published: December 2004

Cobalt‐chromium‐based alloys are widely used in oral and orthopedic implantology. Although they are relatively well tolerated, biological complications could occur which sometimes are due to the insufficient biocompatibility of the alloy. This study shows the effects of an alloy (Co (base), 28% Cr, 5.5% Mo, 1% Ni, 0.95% Si, 0.7% Fe, 0.65% Mn, 0.25% C), on differentiated human cells derived from an oral implantation site, specifically alveolar bone osteoblasts and gingival fibroblasts. The cytocompatibility of the alloy is determined by the study of cell proliferation, determination of total cell protein and in tracellular alkaline phosphatase contents, cytoskeleton, and cell morphology. The alloy is presented to the cells in four different surface states: rough cast specular polished, microbead blasted, and RF sputtered. The results demonstrate that the same material has different effects on the basal and specific cellular functions, according to its surface state. For this alloy we can classify its cytocompatibility according to its surface state in such an order: Microbead blasted ≥ specular polished > RF sputtered > rough cast.
Suspension polymerization of 2‐hydroxyethyl methacrylate in the presence of polymeric diluents: A novel route to spherical highly porous beads for biomedical applications
Authors: Jayakrishnan J. , Thanoo B. Chithambara
Published: December 2004

Spherical, highly porous beads of poly(2‐hydroxyethyl methacrylate) (PHEMA) crosslinke with ethylene glycol dimethacrylate (EGDM) were prepared by suspension polymerization of HEMA in concentrated NaCl solutions in presence of toluene, poly(methyl methacrylate) (PMMA) in toluene, and poly(tetramethylene glycol) (PTMG). Magnesium hydroxide prepared in situ in the dispersion medium gave the best stabilization effect for the monomer droplets. In the presence of PTMG, beads having nearly 1.0 mm in diameter could be prepared, while toluene alone as the diluent produced beads of very small size. Removal of PMMA or PTMG from the beads after polymerization using suitable solvents gave rise to highly porous PHEMA microspsheres. Polymerization in the presence of PTMG produced microspsheres with better spherical geometry as compared to those generated in the presence of PMMA. The effect of various factors such as NaCl concentration, concentration of Mg(OH)2, and the concentration of PMMA or PTMG in the monomer phase on the stability of the suspension and the particle size distribution was investigated.
Tissue reactivity and degradation patterns of absorbable vascular ligating clips implanted in peritoneum and rectus fascia
Authors: Chegini Nasser , Metz Stephen A. , Masterson Byron J.
Published: December 2004

Absorbable vascular ligating clips are finding increasing use in intraabdominal surgery. We report the results of a light and scanning electron microscope investigation of the tissue reactivity and clip degradation patterns of two such materials, Absolok (polydioxanone) and Lactomer (copolymer of glycolic and lactic acid), implanted in the fascia and peritoneum of rabbits for intervals of 2 to 70 days. Cellular response to the clips, defined as the number of inflammatory cells/104 μm2, was maximum at day 4 postimplantation, then gradually declined as the duration of implantation increased. This pattern, seen with both types of clips, was similar to that seen with polydioxanone (PDS) suture, but significantly greater than that associated with polypropylene (Prolene) suture. Although cellular response to the clips was greater in peritoneum than in fascia, especially on two occasions associated with adhesion formation, this was not statistically significant. Based on our morphological observations, the signs of clip degradation which were indicated by the appearance of surface crazing and cracks occurred earlier in peritoneum than in fascia.
Study of soft tissue ingrowth into canine porous coated femoral implants designed for osteosarcomas management
Authors: LaBerge M. , Bobyn J. D. , Rivard C. H. , Drouin G. , Duval P.
Published: December 2004

The objective of this project was to characterize soft tissue bonding to porous coated implants such as those that would be used for resection‐reconstruction of osteosarcoma cases. We were interested in determining conditions which would provide both mechanical attachment of the implant to the surrounding tissue and produce a vascularized interface. In a bilateral canine implant model, both femoral midshafts were replaced with a porous coated cobalt‐chrome segmental implant fabricated with average pore sizes of 300 μm or 900 μm. Twelve implants, six of each pore size, were used in six dogs. Two dogs were sacrificed at 2, 4, and 6 months after implantation. The soft tissue‐implant interface was characterized mechanically with peel tests and histologically using light microscopy and immunohistochemistry. At all periods, a nonvascularized fibrous membrane surrounded the smaller pore size implants, without ingrowth or mechanical bonding. In contrast, a vascularized membrane developed within and around the larger pore size implants; the attachment strength increasing with implantation time. The vascularity increased in size and quantity with time. This study demonstrates the feasibility of obtaining vascularized soft tissue attachment to tumor replacement implants with appropriate porous coated implant design.
Detection of surface‐adsorbed (lipo)proteins by means of a two‐step enzyme‐immunoassay: A study on the Vroman effect
Authors: Poot A. , Beugeling T. , van Aken W. G. , Bantjes A.
Published: December 2004

In view of reports on the involvement of high‐molecular‐weight (HMW) kininogen and high‐density lipoprotein (HDL) in the Vroman effect, we studied the adsorption of fibrinogen, HMW kininogen, HDL and several other proteins from pooled human plasma and congenitally HMW kininogen‐deficient plasma onto glass and low‐density polyethylene, both as a function of the plasma concentration and the contact time. Mixtures of purified (lipo)proteins were also included in the study. Protein adsorption was determined by means of a two‐step enzyme‐immunoassay. Our results support the hypothesis that HMW kininogen is involved in the displacement of fibrinogen, which is almost instantly adsorbed from normal plasma onto glass. On hydrophobic polymers like polyethylene, the low amounts of adsorbed fibrinogen and HMW kininogen from plasma and concentrated plasma solutions may be due to a preferential adsorption of HDL.
Mechanical property studies of human gallstones
Authors: Stranne Steven K. , Cocks Franklin H. , Gettliffe Roland
Published: December 2004

The recent development of gallstone fragmentation methods has increased the significance of the study of the mechanical properties of human gallstones. In the present work, fracture strength data and microhardness values of gallstones of various chemical compositions are presented as tested in both dry and simulated bile environments. Generally, both gallstone hardness and fracture strength values were significantly less than kidney stone values found in previous studies. However, a single calcium carbonate stone was found to have an outer shell hardness exceeding those values found for kidney stones. Diametral compression measurements in simulated bile conclusively demonstrated low gallstone fracture strength as well as brittle fracture in the stones tested. Based on the results of this study, one may conclude that the wide range of gallstone microhardnesses found may explain the reported difficulties previous investigators have experienced using various fragmentation techniques on specific gallstones. Moreover, gallstone mechanical properties may be relatively sensitive to bile‐environment composition.
Differential effects of eight metal ions on lymphocyte differentiation antigens in vitro
Authors: Bravo Isabel , Carvalho Graça S. , Barbosa Mário A. , de Sousa Maria
Published: December 2004

In vitro studies were conducted to determine the effects of metal ions known to be released from metallic implants in vivo on the expression of lymphocyte surface antigens. Normal human peripheral blood lymphocytes were exposed to various concentrations of metal ions (Fe3+, Ni2+, Co2+, Mo6+, V5+, Cr6+, Cr3+, and Ti3+) for 30 min at 37°C in a 5% CO2 atmosphere, and then analyzed for their ability to form rosettes with sheep red blood cells. Following this preliminary analysis, lymphocytes were exposed to the metal ions found to inhibit the E‐rosette reaction (Fe3+, Ni2+, and Co2+) in order to determine which of the following surface antigens were affected: CD2, CD3, CD4, CD8, CD1, CD22, CD10, and HLA‐DR. Our results showed that the in vitro treatment of lymphocytes with Fe3+ or Co2+ caused inhibition of CD2 only, whereas Ni2+ caused inhibition of both CD2 and CD3 antigens. These findings suggest that Fe3+, Co2+, and Ni2+ ions may interfere with T cell activation since both CD2 and CD3 are involved in that process.
Reduced thrombogenicity of polymers having phospholipid polar groups
Authors: Ishihara Kazuhiko , Aragaki Runa , Ueda Tomoko , Watenabe Akihiko , Nakabayashi Nobuo
Published: December 2004

The thrombogenicity of polymers having a phospholipid polar group, poly(2‐methacryloyloxyethyl phosphorylcholine (MPC)‐co‐n‐butyl methacrylate (BMA)), was evaluated by a microsphere‐column method with attention to the activation and adhesion of platelets on the polymer surface. When citrated platelet‐rich plasma (PRP) contacted with the polymers, a large number of platelets adhered and aggregated on poly(BMA). The number of adherent platelets decreased and deformation and aggregation were suppressed with increasing MPC composition. The same tendency was noted when Ca2+‐re‐added PRP came in contact with the polymers. In the case of poly(MPC‐co‐BMA) with 0.320 mole fraction of MPC, activation of platelets and formation of fibrin were completely suppressed. Therefore, MPC moieties in the polymer play an important role in the reduction of thrombogenicity of the polymer.