bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological activity and histocompatibility of dense Al2 O3/MgO ceramic implants in rats
Authors: Griss Peter , von Andrian‐Werburg Hans , Krempien Burghard , Heimke Gunther
Published: May 2005

Three types of dense alumina oxide ceramic (Al2O3) 99.7%, MgO 0.3%; density more than 3.9 g/cm3 differing only in their average grain size (5–15μ) and stainless steel (V4A) plates were implanted into the left femur of male Wistar rats 6 months old. Light and scanning electron microscopic techniques were used to investigate tissue reaction and the ceramic surface. Both ceramic and stainless steel plates were surrounded by a soft tissue layer that differed greatly depending on the implant type in respect to the fiber/cell ratio. While the body tended to enclose the metal plate with a small more or less avascular tissue mostly composed of fibers and some inactive fibrocytes, around the ceramic implants a highly cellulated soft tissue of mesenchyme character developed with signs of osteoblast and chondrocyte metaplasia. Adjacent to this mesenchyme a dense cuff of newly formed woven bone arose, showing numerous active osteocytes. Both metaplastic tendency of the newly formed messenchyme and osteocyte activity in the surrounding bone did not decrease remarkably towards the end of the experiment (70 weeks after operation), while the tissue around metal implants reached a steady relatively reactive state 12–24 weeks after operation. Intimate ceramic surface‐mesenchyme contacts without foreign body reactions supported the idea that alumina oxide ceramic tends to be incorporated into the body's physiological environment while metals are “excluded” by fibrous tissue layers of low biological activity. Corrosion on the ceramic surface was not detectable.
Platelet adhesion onto microcapsule membranes with different degrees of sulfonation
Authors: Muramatsu Nobuhiro , Kondo Tamotsu
Published: May 2005

Microcapsules having different numbers of sulfonic acid groups on their surfaces were prepared by the interfacial polycondensation method. Platelets adhered to these capsules, and the rate and degree of platelet adhesion were found to be remarkable on those microcapsules that had high surface charge compared to those with low surface charge. This trend was strengthened by the coating of the capsules with plasma, while the electrophoretic mobilities of the plasma‐coated capsules showed a considerable reduction and no appreciable difference between the respective mobilities could be observed. This trend suggest that the adsorption of plasma components on microcapsules, and not their surface negative charge, affected platelet adhesiveness directly. In connection with the glycosyl transferase hypothesis, the adsorption pattern and its effect on platelet adhesion of albumin, γ‐globulin, and fibrinogen were examined. The protein adsorption pattern varied depending on both the type of protein and the magnitude of negative charge on the microcapsule surface, but its effect on platelet adhesion was not fully consistent with the glycosyl transferase hypothesis. It was concluded from the findings that the surface negative charge of the capsules strongly affected the composition, molecular orientation, and/or configuration of the adsorbed plasma components, which probably induced the differences in platelet adhesiveness depending on the magnitude of surface negative charge of the microcapsules.
Polyester prostheses as substitutes in the thoracic aorta of dogs. I. Evaluation of commercial prostheses
Authors: Guidoin R. , Gosselin C. , Martin L. , Marois M. , Laroche F. , King M. , Gunasekera K. , Domurado D. , Sigot‐Luizard M. F. , Blais P.
Published: May 2005

Using canine models, a representative selection of polyester or Dacron vascular prostheses, including woven, knitted, and velour types, were evaluated for their relative healing characteristics and for their structural changes during implantation. Following residence periods ranging from 4 h to 6 months at the site of the thoracic aorta, the dogs were sacrified, and the grafts were excized for measurement of the thrombogenicity of the flow surface and for pathological examination by light microscopy and SEM. The kidneys were also removed and examined for infarcts caused by any trapped circulating emboli. The extent of healing, the presence of embolizing nuclei, and the thrombogenicity and morphology of the lumen surface were also assessed. The healing characteristics of each type of device proved similar. Velour fabrics exhibited more extensive encapsulation, but frequently their internal capsules failed to incorporate all the fibers. In all cases, cellular development on the lumen was limited to areas contiguous to the anastomoses. The initial porosity of the devices as measured by water permeability did not appear to influence the healing sequence to a significant extent. The grafts did exhibit differences in structural stability depending on whether they were of a knitted or woven construction. We suggest that users consider these different mechanical and structural properties when making their choice of a graft. Despite these differences, we believe that the healing process is far more host dependent than graft dependent.
Comparative studies by cell culture and in vivo implantation test on the toxicity of natural rubber latex materials
Authors: Ikarashi Yoshiaki , Toyoda Kazuhiro , Ohsawa Naomi , Uchima Takao , Tsuchiya Toshie , Kaniwa Masa‐Aki , Sato Michio , Takahashi Michihito , Nakamura Akitada
Published: May 2005

Colony assay using V79 cells, the agar diffusion assay with L929 cells, and the 7‐day rabbit muscle implantation test were employed to evaluate the cytotoxicity and tissue toxicity of natural rubber latex (NRL) materials. The in vivo implantation test showed that, among 13 histological parameters, thickness of inflammatory layer was the most useful index to evaluate tissue responses quantitatively. A comparison of the in vivo and in nitro parameters revealed the following correlations between the thickness of the inflammatory layer and cytotoxicity indices: Colony assay of the extracts, IC50: r = 0.80; Agar diffusion assay, Zone index: r = 0.73; Lysis index: r = 0.61. From these results, it appears that the colony assay provides a more reliable prediction of the tissue response than the agar diffusion assay.
Protein adsorption of biomedical polymers influences activated monocytes to produce fibroblast stimulating factors
Authors: Bonfield T. L. , Colton E. , Anderson J. M.
Published: May 2005

The studies presented in this manuscript were based upon the hypothesis that monocytes/macrophages selectively produce cytokines and growth factors due to their interactions with polymers and proteins which are adsorbed to their surfaces. These factors in turn selectively influence the ability of fibroblasts to proliferate. The factors which influence fibroblast proliferation were released from monocytes incubated with polymers: Biomer®, polydimethylsiloxane (PDMS), polyethylene (PE), expanded polytetrafluoroethylene (ePTFE), Dacron, and control polystyrene with and without preadsorption with physiological concentrations of IgG, fibrinogen, fibronectin, hemoglobin, or albumin. No simple correlation was found between adsorbed protein, biomedical polymer, and the ability monocytes to produce growth factors and cytokines which influence fibroblast proliferation. This is evidence for selective protein‐polymer interactions which turn selectively activate monocytes produce variable cell cycle competence and progression factors controlling fibroblast growth.
Development of FRP composite structural biomaterials: Ultimate strength of the fiber/matrix interfacial bond in in vivo simulated environments
Authors: Latour R. A. , Black J.
Published: May 2005

Fiber reinforced polymer (FRP) composites are being developed as alternatives to metals for structural orthopedic implant applications. FRP composite fracture behavior and environmental interactions are distinctly different from those which occur in metals. These differences must be accounted for in the design and evaluation of implant performance. Fiber/ matrix interfacial bond strength in a FRP composite is known to strongly influence fracture behavior. The interfacial bond strength of four candidate fiber/matrix combinations (carbon fiber/polycarbonate, carbon fiber/polysulfone, polyaramid fiber/polycarbonate, polyaramid fiber/ polysulfone) were investigated at 37°C in dry and in vivo simulated (saline, exudate) environments. Ultimate bond strength was measured by a single fiber‐microdroplet pull‐out test. Dry bond strengths were significantly decreased following exposure to either saline or exudate with bond strength loss being approximately equal in both the saline and exudate. Bond strength loss is attributed to the diffusion of water and/or salt ions into the sample and their interaction with interfacial bonding. Because bond degradation is dependent upon diffusion, diffusional equilibrium must be obtained in composite test samples before the full effect of the test environment upon composite mechanical behavior can be determined.
A comparative evaluation of the biostability of a poly (ether urethane) in the intraocular, intramuscular, and subcutaneous environments
Authors: Richard Christ F. , Buchen Shelley Y. , Fencil David A. , Knight Patricia M. , Solomon Kerry D. , Apple David J.
Published: May 2005

A transparent poly (ether urethane) (PEU) was considered for use as a foldable intraocular lens material. The PEU was found to possess excellent mechanical, optical, and surface characteristics for this application. In uitro hydrolytic and ultraviolet aging studies suggested the PEU to be tolerant to conditions simulating 3–10 years of normal intraocular exposure. Different behavior was obtained, however, from intraocular and subcutaneous implantation of the PEU. After 6 months of intraocular exposure in the feline model, prototype PEU lenses had lost most or all of their optical resolving power. SEM analysis demonstrated scattered pitting and cracking on the lens surfaces. Degradation was found to be more extreme after as little as 30 days of subcutaneous exposure in rabbits. Severe pitting over the entire surface of implanted flat PEU specimens was observed by SEM. Macroscopic examination showed the samples to be frosty in appearance. It was postulated that the subcutaneous implant environment provides an accelerated in uivo model for materials intended for intraocular use. A minimum acceleration of 6–10X was estimated on a preliminary basis. The PEU studied here was found to be unsuitable for use as a foldable intraocular lens material.
Physical and biological properties of a new synthetic amino acid copolymer used as wound dressing
Authors: Eloy R. , Brack A. , Dorme N. , Cornillac A. M.
Published: May 2005

Anew synthetic amino acid copolymer has been evaluated as wound covering. It is permeable to water vapor in the region of 4.1 kg/m2/24 h, it does not allow microbial proliferation after in vitro inoculation, it is impermeable to bacteria, and is stable and flexible. In vivo experiments were designed to provide qualitative and quantitative evaluation on its possible use as a skin substitute in full‐thickness skin excision in the guinea pig. Two excisions, approximately 12–;14 cm2 were performed on each side of the spine, leaving the panniculus carnosus. One site was treated with the membrane, the other with gauze. Each animal served as its own control. Photographs with a fixed focal‐length camera were taken in identical conditions for all wounds immediately and 7,14, and 21 days after excision. They were analyzed by planimetry. Histological studies were performed at 7,14, and 21 days. The rate of healing between 0 and 21 days of the wounds treated with the copolymer membrane was significantly accelerated in comparison with wounds covered with a dry dressing (p < 0.05). This increased epithelialization rate was confirmed by histology, which also suggested a reduction of the inflammatory response of the wound. In vivo biodegradation studies were also performed by subcutaneous implantation in the rat followed at 15, 30, 60, and 90 days by histology and physicochemical analyses. The results demonstrate that the membrane is not biodegradable.
Development and use of a parallel‐plate flow chamber for studying cellular adhesion to solid surfaces
Authors: van Kooten T. G. , Schakenraad J. M. , Van der Mei H. C. , Busscher H. J.
Published: May 2005

A parallel‐plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the behavior of human fibroblasts spread on glass is studied when exposed to an increasing laminar flow. The flow system appears to be well‐suited for following individual cells during detachment. After 75 to 90 min, at a shear stress of 350 dynes/cm2, more than 50% of the spread cells are detached from the surface. Cells with higher spreading areas stay longer at the glass surface. Cells round up before detaching. Sometimes the cell body is attached to the substratum through a thin filament during detachment. At the scanning electron microscopy level numerous filopodial extensions are observed. Cell material could only rarely be observed at the light or scanning electron microscopic level on the substratum once a cell was detached.
Effect of local hemostatics on bone induction in rats: A comparative study of bone wax, fibrin–collagen paste, and bioerodible polyorthoester with and without gentamicin
Authors: Solheim Eirik , Pinholt Else Marie , Bang Gisle , Sudmann Einar
Published: May 2005

Local hemostatics for osseous tissue should preferably be absorbable and biocompatible and should not inhibit osteogenesis. The tissue response and effect on demineralized boneinduced heterotopic osteogenesis in the abdominal muscle of 120 male Wistar rats by different local hemostatics were evaluated by light microscopy and 85Sr uptake analyses. Nonabsorbable bone wax of 88% beeswax and absorbable bovine fibrin–collagen paste both significantly inhibited o st eoinduction, whereas a bioerodible polyorthoester drug delivery system with or without 4% gentamicin did not. Bone wax was not absorbed and induced a chronic foreign body reaction. Fibrin–collagen paste induced less inflammation with numerous monocytes and macrophages with engulfed material. Bioerodible polyorthoester caused a very moderate tissue reaction and was mostly resorbed at week 4.
Stimulation of neutrophil movement by metal ions
Authors: Hunt J. A. , Remes A. , Williams D. F.
Published: May 2005

The interaction between corrosion products of metallic implants and the surrounding tissue is important in determining the biocompatibility of the implant, in particular the interaction of corrosion products with inflammatory cclls such as neutrophils and macrophages. Such cells are capable of releasing enzymes and high‐energy oxygen radicals which can damage the tissue. Clearly, any factors that influence cell movement to the implant site could influence the biocompatibility of the implant. The present study examined the influence that copper and nickel ions had on neutrophil locomotion. Both copper and nickel ions stimulated a proportion of the neutrophil population to take up a nonspherical morphology and to locomote. These metal ion stimulated cells have higher circularity values and move slower than neutrophils incubated with FM1.P. For both FMLP and nickel ion stimulated cells, there is a correlation between the speed of neutrophil locomotion and neutrophil circularity; as the neutrophil circularity value decreases, the speed of locomotion increases.
Cytokine and growth factor production by monocytes/macrophages on protein preadsorbed polymers
Authors: Bonfield T. L. , Colton E. , Marchant R. E. , Anderson J. M.
Published: May 2005

These studies evaluate the effect of biomedical polymers: Biomer, polydimethylsiloxane (PDMS), polyethylene, expanded polytetraf luoroethylene (ePTFE), Dacron, and the control polystyrene with or without adsorbed proteins IgG, fibrinogen, and fibronectin on the ability of activated human monocytes/macrophages to produce Interleukin 1 Beta (IL‐1‐B), Interleukin 6 (IL‐6), and Tumor Necrosis Factor Alpha (TNF‐A). Monocytes/macrophages incubated on biomedical polymers with or without protein preadsorption produce variable levels of IL‐1‐B, IL‐6, and TNF‐A dependent on the polymer and adsorbed protein. IL‐6 was produced in the greatest quantity and was the most influenced by protein adsorption. ePTFE and PDMS polymers were least stimulating while polystyrene was the most stimulating of monocyte activity. Adsorbed IgG consistently altered the ability of the polymers to activate monocytes/macrophages to produce cytokines. These studies provide important insight into conditions which modulate monocyte/macrophage activity in response to protein preadsorbed biomedical polymers.
Adhesive bone cement containing hydroxyapatite particle as bone compatible filler
Authors: Ishihara Kazuhiko , Arai Jorplo , Nakabayashi Nobuo , Morita Sadao , Furuya Kotaro
Published: May 2005

Acrylic bone cement containing hydroxyapatite (HA) as a filler was developed using 4‐methacryloyloxyethyl trimellitate anhydride (4‐META) to promote adhesion both to bone and HA. The mechanical strengths of the cement did not decrease significantly with increasing HA in the cement by 4‐META. However, strengths decreased with increasing HA content in the absence of 4‐META. Scanning electron micrographic examination of fractured surfaces of the cement clearly showed that the HA particles adhered to the matrix resin when 4‐META was added. Thus, it was important to maintain the original mechanical strengths for 4‐META. The HA particles along the surface increased with increased HA content in the cement. The cement adhered to bone with a tensile bond strength was higher than 10 MPa.
Thrombin and albumin adsorption to PVA and heparin–PVA hydrogels. I. Single protein isotherms
Authors: Smith Barbara A. H. , Sefton Michael V.
Published: May 2005

More radiolabeled thrombin was adsorbed to heparin‐polyvinyl alcohol (PVA) than to PVA, consistent with a specific interaction with the immobilized heparin. The maximum surface concentration on heparin‐PVA was estimated to be ∼450 nmol/m2 with an apparent affinity constant (Ka,) of 2.5μM−1; on PVA, the plateau concentration was 10 nmol/m2 with a Ka < 1 nM−1. There was little difference in bovine serum albumin (BSA) adsorption between PVA and heparin PVA. Interestingly, thrombin adsorption to polyethylene was indistinguishable from that to PVA despite the large difference in surface chemistry. BSA adsorbed to polyethylene with higher affinity than to the hydrogels, although the plateau concentrations were comparable. The adsorbed thrombin was biologically inactive at least towards chromogenic substrate, with the residual activity on PVA unaffected by subsequent incubations with antithrombin 111. PVA and heparin‐PVA presented a heterogeneous and complex substrate for interaction with proteins. The adsorbed protein was likely present in multiple states depending on the groups with which it interacted.
Short‐term response of brain tissue to cerebrospinal fluid shuntsin vivoandin vitro
Authors: Del Bigio Marc R. , Fedoroff Sergey
Published: May 2005

The purpose of the studies was to determine how gross physical characteristics of cerebrospinal fluid (CSF) shunts and the cellular proliferative response to shunts contribute to shunt obstruction. Ventricular catheters with round holes, slots, and flanges were implanted into the lateral ventricles of rabbits for 4 weeks. All shunt designs were subject to ingrowth of tissue from the ventricle wall or choroid plexus. There were no qualitative or quantitative differences between normal and hydrocephalic rabbits. Astroglial cells from newborn mice were cultured on shunt catheters for 2 or 4 weeks, The growth of these cells was poor, probably because the cells cannot attach well to the silicone rubber substrate. Contact between the shunt catheter and vascularized brain tissue is the most important factor in the genesis of shunt obstruction. © 1992 John Wiley & Sons, Inc.
Influence of calcium concentration on the dentin wettability by an adhesive
Authors: Panighi M. , G′Sell C.
Published: May 2005

Plane dentin surfaces were abraded perpendicular to the radicular axis of sound human molars. They were cleaned to reveal the tubules, and the morphological features of each surface were studied microscopically. For a first series of teeth, the Vickers microhardness of the dentin surfaces was measured and the calcium and phosphorus composition was determined by electron microprobe analysis. For a second series, the microhardness and wettability of the surface by the Scotchbond adhesive were compared. Positive correlations were found between the following parameters: degree of minerality, dentin compactness, hardness, and spreading capability of the adhesive.
Interactions of thermally denatured fibrinogen on polyethylene with plasma proteins and platelets
Authors: Rubens Fraser , Brash John , Weitz Jeff , Kinlough‐Rathbone Raelene
Published: May 2005

During the investigation of fibrin deposition onto hydrophobic polymers in contact with human blood, a model was developed in which fibrinogen was denatured and irreversibly coated onto a polyethylene surface by heating to 70°C for 10 min. The denatured fibrinogen‐polyethylene surface is resistant to fluid wall shear rates of up to 550 s−1 and the fibrinogen does not desorb in the presence of plasma proteins. Compared to uncoated polyethylene, little albumin or fibrinogen adsorbs to heat‐denatured fibrinogen. Thrombin binds to the denatured fibrinogen‐coated polyethylene with low affinity and also acts on the surface‐bound denatured fibrinogen and cleaves fibrinopeptide A (FPA) quantitatively. Washed, 51Cr‐labeled platelets do not adhere to the thermally denatured fibrinogen at either low or high shear rates compared to surfaces coated with undenatured fibrinogen (p < 0.01). These observations support the role of the D domain of fibrinogen in platelet adhesion because this is the region that is denatured by heating. In contrast, the E domain of fibrinogen is not altered by heating to 70°C and hence remains susceptible to thrombin and/or plasmin cleavage. The characteristics of this surface are such that it can be used to develop fibrin‐coated surfaces for use in studies of thrombus formation on artificial surfaces. © 1992 John Wiley & Sons, Inc.
Porosity of porcine small‐intestinal submucosa for use as a vascular graft
Authors: Hiles M. C. , Badylak S. F. , Geddes L. A. , Kokini K. , Morff R. J.
Published: May 2005

The porosity of a vascular graft material has been suggested as a major factor affecting the rate and degree of neovascularization of newly implanted grafts, with higher porosites generally associated with better performance. The objective of this study was to determine the water porosity of a new vascular graft material, small‐intestinal submucosa (SIS), and to compare the values to those reported for other common vascular graft materials. In addition, the porosity of SIS was investigated with respect to applied pressure and applied uniaxial tension. Both rectangular, flat specimens and tubular specimens of SIS were subjected to static water pressure, and water was collected as it passed through the SIS material. SIS has a typical porosity of 0.52 mL/min · cm−2 at an applied pressure of 120 mm Hg. Although porosity appeared to be unaffected by uniaxial tension, it increased in proportion to applied pressure at a rate of 4.8 × 10−3 mL/min · cm−2/mm Hg. Theselow porosity values and the past success of SIS as a vascular graft material suggest that high‐porosity materials are not required for implant succes. © 1993 John Wiley & Sons, Inc.
Competitive adsorption of albumin against collagen at solution–air and solution–polythylene interfaces
Authors: Baszkin A. , Boissonnade M. M.
Published: May 2005

The adsorption of human serum albumin (HSA) from the binary mixtures with collagen was monitored at solution–air and solution–polyethylene interfaces by the in situ measurements. The results clearly demonstrate that on both interfaces albumin is the only adsorbing protein within a large collagen solution concentration range. At the albumin concentration equal to 0.005 mg/mL, the presence of collagen in solution results in the enhancement of albumin adsorption at solution‐air interface relative to its adsorption from the single protein system. The same phenomenon is manifested at the solution‐polyethylene interface, although the increase in albumin adsorption at this interface occurs at the albumin concentration equal to 0.01 mg/mL. These results are attributed to the lowering in the solution–air and solution–polyethylene interfacial tensions, and thus to the increase in the spreading characteristics of albumin in the presence of collagen molecules. The desorption experiments carried out with a buffer solution on polyethylene surfaces reveal the irreversibility of adsorbed albumin from both the single and the binary mixtures with collagen. When after 20 h of adsorption from the solutions containing albumin only, collagen was added to these solutions or when the samples after that period of time were first rinsed with a buffer and then with a collagen solution, the amounts of albumin remaining at the surfaces were in both cases reduced by one‐half. © 1993 John Wiley & Sons, Inc.
Hydrolytic degradation and morphologic study of poly‐p‐dioxanone
Authors: Lin Hui Ling , Chu C. C. , Grubb D.
Published: May 2005

Thein vitrohydrolytic degradation of 2‐0 size PDS monofilament suture was studied for the purpose of revealing its morphologic structure and degradation mechanism. The sutures were immersed in phosphate buffer of pH 7.44 for up to 120 days at 37°C. These hydrolyzed sutures were examined by the changes in tensile properties, weight, thermal properties, x‐ray diffraction structure, surface morphology, and dye diffusion phenomena. It was found that hydrolysis had significant effects on the change of PDS fiber morphology and properties. Hydrolysis, however, had no significant effect on overall molecular orientation of the fiber until the very late stage. PDS suture fibers retained their skeleton throughout the earlier periods of hydrolysis concurrent with mass and tensile strength losses. PDS sutures exhibited an absorption delay of 120 days. Both heat of fusion and melting point exhibited a maximum function of hydrolysis time. Hydrolysis of PDS suture fibers proceeded through two stages: random scission of chain segments located in the amorphous regions of microfibrrils and intermicrofibrillar space, followed by stepwise scission of chain segments located in the crystalline regions of microfibrils. Dye diffusion data showed that the passage along the longitudinal direction of the fiber was relatively easier than the lateral direction as evident in the diffusion coefficient, activation energy, and flexibility of chain segments. Swiss‐cheese model of fiber structure appears to describe the observed dye diffusion phenomena and their dependence on hydrolysis time and dying temperature. © 1993 John Wiley & Sons, Inc.
Surface atomic and domain structures of biomedical carbons observed by scanning tunneling microscopy (STM)
Authors: Feng L. , Andrade J. D.
Published: May 2005

STM has been used to study the surface domain and atomic structures of three biomedical carbons: glassy carbon (GC), low‐temperature isotropic carbon (LTI), and ultra‐low‐temperature isotropic carbon (ULTI). The images show atomic lattices on both GC and LTI, but not on ULTI. The lattices contain many defects; lattices in GC are more ordered than those in LTI. The images also show patchlike carbon crystallites with sizes of 3–15 nm for GC, 2–8 nm for LTI, and 1–3 nm for ULTI. The crystallites form surface domains that may differ in surface properties due to different orientations of the crystallites. Mechanical polishing makes the LTI surface more amorphous and more homogeneous. Based on the STM observations, we evaluate several hypotheses on the blood compatibility of biomedical carbons. © 1993 John Wiley & Sons, Inc.
Preparation of poly(glycolic acid) bonded fiber structures for cell attachment and transplantation
Authors: Mikos Antonios G. , Bao Yuan , Cima Linda G. , Ingber Donald E. , Vacanti Joseph P. , Langer Robert
Published: May 2005

A novel method was developed to prepare threedimensional structures with desired shapes used as templates for cell transplantation. The produced biomaterials are highly porous with large surface/volume and provide the necessary space for attachment and proliferation of the transplanted cells. The processing technique calls for the formation of a composite material with nonbonded fibers embedded in a matrix followed by thermal treatment and the selective dissolution of the matrix. To evaluate the technique, poly(glycolic acid) (PGA) fiber meshes were bonded using poly(L‐lactic acid) (PLLA) as a matrix. The bonded structures were highly porous with values of porosity up to 0.81 and area/volume ratios as high as 0.05 μm−1. © 1993 John Wiley & Sons, Inc.
Determination of the role of cuticular carbohydrates in the hemocompatibility of Dirofilaria immitis (Nematoda)
Authors: Kadipasaoglu Kamuran A. , Bilge Fertac H. , Baier Robert E.
Published: May 2005

We have partially characterized surface glycoproteins of the canine heartworm, Dirofilaria immitis. Histochemical studies indicated the presence of neutral and acidic mucopolysaccharides at the blood–cuticle interface. Fluorescein isothiocyanate‐conjugated lectin binding patterns suggested the presence of α‐D‐glucosyl and/ or α‐D‐mannosyl, β‐galactosyl, N‐acetylneuraminyl and N‐acetylated‐D‐hexosaminyl (sialic and glucuronic acids, respectively) terminal residues among the constituent sugars of the glycocalyx. An additional goal of this study was to assess the significance of each carbohydrate in parasite hemocompatibility by using scanning electron microscopy, internal reflection infrared spectroscopy, and comprehensive contact angle measurements. Each carbohydrate identified in the glycocalyx was selectively cleaved with the appropriate exoglycosidase. Heartworms bearing native and enzyme‐altered surfaces were exposed to platelet‐rich canine plasma. Activation and aggregation of platelets were significantly increased on enzyme‐treated surfaces as compared with native surfaces. Enzyme‐induced cleavage of carbohydrate residues was associated with an increase in critical surface tension or a loss in cuticular structural integrity or both. Hemocompatibility of the heartworm cuticle depends on the retention of a stable saccharide‐rich layer that minimizes interaction with plasma proteins and platelets; thus, carbohydrate residues on the glycocalyx may contribute to parasite hemocompatibility. The presence of similar low‐critical‐surface‐tension coatings with high mechanical integrity may impart thromboresistance to other polyphenolic or chitinous substances. © 1993 John Wiley & Sons, Inc.
Uptake of metal cations by fibroblasts in vitro
Authors: Wataha J. C. , Hanks C. T. , Craig R. G.
Published: May 2005

Atomic absorption spectroscopy was used to assess uptake of Ag+1, Au+4, Cd+2, Cu+2, In+3, Ni+2, Pd+2, and Zn+2 by in vitro cultures of Balb/c 3T3 fibroblasts as a function of concentration of the cations in cell‐culture medium. Reversibility of this uptake was also measured. Metal cations exhibited a 400‐fold difference in their tendency to accumulate in the cells; In+3 tended to accumulate the most, whereas Pd+2 accumulated the least. Uptake of the cations in the cells increased linearly with the concentration of the cation in the medium for all cations up to their 50% toxicity concentrations. Reversal of this uptake was slower than that of the initial uptake for three cations studied in more detail (Cd+2, In+3, and Ni+2). The duration of the initial exposure affected the proportion of the metal cations that were retained by the cells 5 h after the cations were removed from the medium. The proportion of retained Cd+2 did not change when the initial exposure was increased from 2 h to 6 h, whereas the proportion of retained In+3 decreased and Ni+2 increased over the same period. The tendency of the cells to accumulate these cations correlated with their cytotoxic potency (measured previously). © 1993 John Wiley & Sons, Inc.
Tissue reaction to alumina implants inserted into the tibiae of rats
Authors: Takeshita Fumitaka , Morimoto Keizo , Suetsugu Tsuneo
Published: May 2005

We examined the tissue reaction to three alumina implants—single‐crystal alumina (SA), dense polycrystal alumina (DPA), and porous polycrystal alumina (PPA)—inserted transcortically, extending into the medullary canal of rat tibiae, and assessed the quantitative differences in bone reaction using an image processing system. There was no difference in the degree of maturation of newly formed bone around the three kinds of alumina. SA and DPA were encapsulated with a continuous bone layer, but some bone tissue was attached focally around PPA. Bone trabeculae in the control site diminished in size and number chronologically. Multinucleated giant cells were observed on the surface of DPA and PPA, but not on SA. Tabulation of the quantitative evaluation indicated that SA showed the highest, DPA a lower, and PPA the lowest in bone contact rate, bone contact thickness, and bone contact area. These data suggest that SA is superior to the other two as an implant material. © 1993 John Wiley & Sons, Inc.
Solution effects on the surface reactions of a bioactive glass
Authors: Filgueiras M. Regina , La Torre Guy , Hench Larry L.
Published: May 2005

The in vitro surface reactions of a 45S5 bioactive glass in three simulated body fluids (SBF) are analyzed using Fourier transform infrared (FTIR) spectroscopy. Five reaction stages are observed. Calcium and phosphate ions in SBF accelerate to a small extent the repolymerization of silica (Stage 3) and formation of an amorphous calcium‐phosphate (a‐CP) layer (Stage 4) on the glass surface. The a‐CaP layer is crystallized to form hydroxycarbonate apatite (HCAp) (Stage 5) more rapidly in the Ca‐and P‐containing SBF solutions (in 90 min rather than 120 min). However, Mg ions in SBF slow down formation of the a‐CaP layer and greatly retard crystallization of HCAp on the glass surface. © 1993 John Wiley & Sons, Inc.
Analysis of apatite deposits on substrates
Authors: Dasarathy Harini , Riley Clyde , Coble H. Dwain
Published: May 2005

Calcium phosphate coatings, important for medical implant applications can occur in several different phases. Because of differences in properties of these phases it is imperative to be able to identify their presence in a substrate's coating. In this study we characterized hydroxy apatite (HA) surfaces applied by four different coating procedures. Included were plasma sprayed, sputtered, a composite, and a composite overlayed with plasma sprayed. It was found that a combination of reflectance infrared and Raman spectroscopy could be utilized to make an in situ characterization of the calcium phosphate phases. It was shown that plasma sprayed and sputtered coatings of HA lost OH and thus decreased in crystallinity, while composite coatings remained unchanged from the original HA powder. © 1993 John Wiley & Sons, Inc.
Effect of interfacial variables on metal‐porcelain bonding
Authors: Wagner Warren C. , Asgar Kamal , Bigelow W. C. , Flinn Richard A.
Published: May 2005

While ceramic‐to‐metal bonding has been used in many applications, the actual chemical and physical factors leading to optimum bond strength are not well understood. In this work, several variables affecting the bonding between dental porelain and a palladium alloy (85% Pd, 10% Cu, and 5% Ga) were investigated: (1) precoating the metal by sputtering various oxides before porcelaining; (2) preoxidation of the metal base before porcelaining; (3) porcelaining under reducing atmosphere; and (4) surface roughening at controlled levels before porcelaining.

Using a modification of the push doughnut shear bond strength test to measure bond strength the following results were obtained. (1) Compared with standard “control” samples, the aluminum oxide precoated precoated specimens showed a bond strength improvement of 46%, while the copper, manganese, and tin oxide precoatings exhibited smaller effects. (2) Preoxidation of the metal base led to pronounced bond strengthening (152%) by surface roughening as well as oxide formation. (3) Porcelaining under a reducing atmosphere severely reduced bond strength (88% lower than the controls) indicating the role of oxidation during the standard firing cycle. (4) Mechanical roughening of the surface by controlled amounts gave pronounced improvements with greater notch depth. Coarse roughening produced the highest bond strength improvements (486%). © 1993 John Wiley & Sons, Inc.
Evaluation of a relationship between polymer bulk hydroxyl and surface oxygen content and in vitro serum–material interaction
Authors: Sawada Koji , Shimoyama Takashi , Malchesky Paul S. , Goldcamp James B. , Omokawa Susumu
Published: May 2005

To evaluate serum‐material interaction for six types of minimodule and to assess the relationship between the interaction and chemical composition, notably bulk polymer hydroxyl (OH) percent of polymer, or surface oxygen (SO) percent, polymeric membranes with varying OH and SO percents were evaluated with normal human serum. The membrane materials (OH percent and SO percent) evaluated included polypropylene (PP; 0% and 1.9%), polyvinyl alcohol (PVA; 23.7% and 27.3%), ethylene vinyl alcohol (EVAL 4A and D; 30.4% and 25.3%), Cuprophan (CP; 31.5% and 37.4%), and Hemophan (HP; 30.9% and 23.6%), respectively. Data from serum perfusions expressed as percent changes to sham perfusion showed that solute percent decreases were less than 10% in all materials except PVA (10–22%). PVA and CP had higher C3a, C4a, and C5a, and C3a concentration increases, and had larger suppressive effects for all three mitogen‐induced mononuclear cell transformation functions (MNCTF) and concanavalin A‐induced MNCTF, respectively. PVA had higher SO percent than CP having lower or comparable bulk OH percent to EVAL or HP. The results obtained in the serum material interaction studies related more with the SO percent of the polymer rather than bulk OH percent. The differences for C4a and PHA‐induced MNCTF observed between the two EVAL membranes may be associated with significantly different pore size and therefore different surface structural properties. These results suggest that surface chemical (SO percent on the materials) and structural property analyses are important factors in biocompatibility parameter studies. © 1993 John Wiley & Sons, Inc.
Improved cortical histology after cementation with a new MMA‐DMA‐IBMA bone cement: An animal study
Authors: Nimb Lars , Stärup Jens , Jensen Jørgen Steen
Published: May 2005

The histological response of bone to inert bone wax, conventional polymethylmethacrylate (PMMA), and a new formulation of bone cement, methylmethacrylate/n‐decylmethacrylate/isobornylmethacrylate (MMA/DMA/IBMA) was investigated in canine tibial diaphysis. The new formulation of cement is characterized by a reduced exothermic temperature at curing and reduced leakage of chemicals to the adjacent bone. In comparison with bone wax, the MMA/DMA/IBMA bone cement did not differ significantly with respect to periosteal apposition and bone remodeling, although a tendency to inhibit the biological response was encountered. The MMA/DMA/IBMA was clearly superior to PMMA bone cement in respect to both bone necrosis and repair, as well as bone remodeling. © 1993 John Wiley & Sons, Inc.
Comparison of bone ingrowth into cobalt chrome sphere and titanium fiber mesh porous coated cementless canine acetabular components
Authors: Jasty Murali , Bragdon Charles R. , Haire Teresa , Mulroy Richard D. , Harris William H.
Published: May 2005

Bone ingrowth into uncemented hemispherical canine acetabular components porous‐coated with cobalt chrome spheres was compared to those porous‐coated with titanium fiber mesh. While good bone ingrowth was noted in both types of porous coatings at 6 weeks after surgery with no difference in the histologic quality of the ingrown bone, quantitation of bone ingrowth showed that significantly more bone grew into titanium fiber mesh porous‐coated components. The mean amount of bone ingrowth measured 10.5% of the area of the porous coating with fiber mesh coatings and only 5.5% of the area of the porous coating with spherical coatings (significant difference at P < .0005). The mean area density of the ingrown bone inside the pores measured 21.5% of the pore area with fiber mesh coatings, also significantly greater than 13.4% of the pore area with sphere coatings (P < .025). The ingrown bone penetrated a mean 66% of the depth of the porous layer with fiber mesh coatings compared to 32% of the depth of the porous layer with spherical coating (significant difference at P < .0005). The mean extent of the periphery of the porous layer with bone ingrowth was 88% for the mesh coatings and 55% for the spherical coatings (also a significant difference at P < .01). © 1993 John Wiley & Sons, Inc.
Osseous implant for studies of biomaterials using an in vivo electrochemical transducer
Authors: Casey Fox W. , Miller Michael A.
Published: May 2005

The in vitro and in vivo electrochemical behavior of commercially pure titanium (cp Ti) was characterized using a specialized osseous implant in conjunction with electrochemical impedance spectroscopy (EIS) measurement techniques. Studies performed in vitro were used to verify the operation of the transducer and develop methods of deconvoluting EIS data. This method was subsequently used to describe an electrochemical equivalent circuit model of the surface oxide and electrical doublelayer capacitance of cp Ti in the endogenous electrolyte found in the medullary compartment of a baboon tibia. Kinetic profiles of the double‐layer capacitance and the polarization resistance were constructed from multiple in vitro and in vivo EIS measurements performed over 60 min at 0 V (reference Ag/AgCI) conditioning potential. The profiles demonstrated that the growth of surface oxides was biphasic, with rapid decrease in the doublelayer capacitance occurring within 20 min and reaching steady‐state conditions at approximately 40 min. These data suggested that a passive, stable biofilm formed on the cp Ti surface in vivo and in vitro. © 1993 John Wiley & Sons, Inc.
Osteogenesis at the dental implant interface: High‐voltage electron microscopic and conventional transmission electron microscopic observations
Authors: Steflik D. E. , Sisk A. L. , Parr G. R. , Gardner L. K. , Hanes P. J. , Lake F. T. , Berkery D. J. , Brewer P.
Published: May 2005

The osteogenesis of mandibular bone to endosteal dental implants was examined using an in vivo dog model. One half of the implants examined were unloaded implants, with the remaining one half prosthodontically loaded for 6 months. Undecalcified mandibular implant samples were examined with both high‐voltage electron microscopy (HVEM) stereology and routine transmission electron microscopy. The osseous interface to integrated implants was shown to vary in its morphology. Mineralized bone was observed directly apposing the implant, often separated from the implant by an electron‐dense deposit of approximately 50 nm. Within this densely mineralized matrix, osteocytes were routinely observed. Adjacent areas were shown to contain slightly wider zones of either a less dense mineralized matrix or, alternatively, unmineralized tissue. Other zones consisted of wider unmineralized matrices containing collagen fibers and osteoblasts. These latter zones were consistent with the appearance of an appositional type of bone growth. Because bone is a dynamic, actively remodeling tissue, a varied morphology of the support tissues to dental implant is not unexpected. Areas of mature bone interfacing with successfully integrated implants were demonstrated, as well as areas adjacent to the mature bone that were undergoing remodeling or mineralization. This study has also shown that HVEM stereology is a valuable research tool to investigate the oral tissue interface with dental implants. © 1993 John Wiley & Sons, Inc.
Biocompatibility testing of restorative materials influencing dentin and pulp
Authors: Dejou J. , Remusat M. , Franquin J. C.
Published: May 2005

A comparative study was carried out using 27 healthy human bicuspids that had been extracted for orthodontic reasons from adolescents 11–14 years old. A microphotometrical analysis of buccal and lingual odontoblast layer thickness was performed using the SAMBA 2000 system and the results were submitted to statistical comparison. The buccal odontoblast layer (BOL) was found to be thicker than the lingual odontoblast layer (LOL). These results were independent of age, sex, and tooth position in the dental arch. Moreover, a strong relationship existed between the layer thicknesses as linear function on a logarithmic scale. Standards for the evaluation of pulp–dentin biocompatibility are based essentially upon qualitative or semiquantitative histological criteria. A method of quantitative evaluation based upon microphotometrical measurements of the thickness of the buccal odontoblast layer, considered variable, and the lingual odontoblast layer, considered stable, was applied to coronal filling materials that had previously been tested by a classic method. Seventy bicuspids extracted from adolescents 11–14 years of age whose class‐V cavities had been filled in situ with one of four restorative materials, and whose residual dentin thickness was less than 750 μm, were divided into two groups: an intermediate‐term group (A) and a long‐term group (B); both groups were subdivided into four experimental series as a function of test materials. A microphotometrical analysis was carried out using an automatic scanning system (SAMBA 2000) for the quantification of buccal and lingual odontoblast layer thicknesses. The results confirmed that due to the stability of the LOL thickness it may legitimately be used as reference in the study of the analogous BOL thickness. The BOL variations seemed proportional to the biocompatibility of the material tested. The quantitative results obtained should provide an accurate comparison of the materials at a given period of observation and substantiate a follow‐up study of the evolution of biocompatibility. © 1993 John Wiley & Sons, Inc.
Polystyrene chemistry affects vitronectin activity: An explanation for cell attachment to tissue culture polystyrene but not to unmodified polystyrene
Authors: Steele John G. , Dalton B. Ann , Johnson Graham , Underwood P. Anne
Published: May 2005

Tissue culture polystyrene (TCPS) supports good attachment of adherent cells whereas unmodified polystyrene (PS) does not, but the mechanism of this difference is not well characterized. We have compared TCPS and PS for the amounts of vitronectin (Vn) and fibronectin (Fn) which adsorb from the fetal bovine serum (FBS) component of the culture medium. The significance of the amounts of Vn and Fn which adsorbed onto TCPS and PS was determined by reference to the concentration dependence of the cell attachment activity of Vn and Fn when adsorbed onto TCPS and PS, assayed using human vein endothelial cells and BHK‐21 fibroblasts. The amount of Vn which adsorbed onto TCPS from medium containing 3–30% (v/v) FBS was supraoptimal for the attachment of endothelial cells and fibroblasts. On PS, the amount of Vn which adsorbed from this medium was less than for TCPS and was suboptimal for cell attachment. Higher levels of Fn adsorbed onto TCPS than to PS, but even the amounts of Fn which adsorbed onto TCPS were suboptimal for cell attachment. We propose that the principal mechanistic difference between TCPS and PS for the initial attachment and spreading of cells is that more Vn adsorbs onto TCPS from the serum component of the culture medium. © 1993 John Wiley & Sons, Inc.