bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro stimulation of fibroblast activity by factors generated from human monocytes activated by biomedical polymers
Authors: Miller K. M. , Anderson J. M. 
Published: December 2004

AbstractBiomedical polymers used in constructing implantable artificial devices may affect host responses to the material and ultimately contribute to the success or failure of a device via mechanisms of cell–polymer interactions. Human peripheral blood monocytes (MO) cultured in the presence of several such biomedical polymers released factors that stimulated fibroblast proliferation and/or collagen synthesis. The factors that stimulated fibroblast proliferation were differentially released from monocytes cultured in the presence of Dacron, polyethylene, expanded polytetrafluoroethylene (ePTFE), polydimethylsiloxane, and polystyrene (control). Supernatants obtained from monocytes cultured in the presence of Biomer, a segmented polyetherurethane, were unable to stimulate fibroblast proliferation. However, supernatants from all cultures, including MO‐Biomer cultures, were able to induce collagen production from the same target fibroblasts. These same supernatants also were shown to contain interleukin 1 (IL1) activity. Neutralization of the fibroblast stimulatory potential (FSP) activity with antibodies directed against human IL1 and human PDGF demonstrated that IL1 and not PDGF was responsible for the FSP activity. Results of this study show that by affecting macrophage activation, different biomedical polymers can affect host biocompatibility responses by altering fibroblast proliferation and function.
Injectable cross‐linked collagen with improved flow properties
Authors: Wallace Donald G. , Rhee Woonza , Reihanian Hertsel , Ksander George , Lee Richard , Braun William B. , Weiss Barbara A. , Pharriss Bruce B. 
Published: December 2004

AbstractAqueous suspensions of glutaraldehyde cross‐linked fibrillar collagen and non‐cross‐linked fibrillar collagen were examined by rheometry, particle size analysis, and microscopic techniques. Although cross‐linked collagen suspensions were similar to non‐cross‐linked suspensions by microscopic and size analyses, they differed in rheometric properties. Concentric cylinder Couette flow, shear creep, uniaxial creep, and porous bed flow all revealed that cross‐linked collagen was more resistant to deformation and flow than non‐cross‐linked collagen. These results were in agreement with in vivo dermal implantation studies, both in pig and human; i.e., compared to non‐cross‐linked collagen, the cross‐linked formulation was more difficult to inject into tissue and did not spread uniformly, sometimes giving rise to palpable lumps or large masses evident in histological sections. When hyaluronic acid was blended with cross‐linked collagen to achieve a final hyaluronate concentration of 5 mg/mL, there was a significant improvement in ease of injection into tissue. Rheometry on blends of hyaluronate and cross‐linked collagen demonstrated that the blend required lower forces to achieve deformation and flow, compared to cross‐linked collagen alone. Particle size analysis on the blend showed a reduction in fiber aggregate dimensions, compared to crosslinked collagen alone.
Student research award in the hospital intern, resident or clinical fellow category, 15th annual meeting of the society for biomaterials, Lake Buena Vista, Florida, April 28–May 2, 1989. An evaluation of purified reconstituted type 1 collagen fibers
Authors: Law J. K. , Parsons J. R. , Silver F. H. , Weiss A. B. 
Published: December 2004

AbstractCollagen fibers composed of type I collagen molecules were studied for biocompatibility and mechanical properties. These fibers were crosslinked using two different processes: (1) glutaraldehyde, (2) dehydration followed by exposure to cyanamide (DHT/C); the latter method produces only urea as a by‐product of the crosslinking process and is postulated to be more biocompatible. An in vitro model using rat tendon fibroblasts growing on individual fibers was used to evaluate outgrowth rates, cell/fiber interactions, and cell morphology. These studies showed an advantage with DHT/C crosslinking, relative to glutaraldehyde crosslinking, in promoting fibroblast growth. In vivo intramuscular implantation in rats showed excellent biocompatibility for both kinds of collagen implants. In addition, aligned ingrowth into the implant from the medial collateral ligament when applied in that location was demonstrated. Mechanical testing demonstrated the higher strength of dry fibers; however, upon hydration, there was a marked decrease in stress to failure. This reduction in strength was due principally to an increase in cross section due to swelling. These collagen fibers appear to be very biocompatible even in the presence of low concentrations of glutaraldehyde. They promote fibrous aligned ingrowth in a setting of ligament healing. Thus, they represent a strong candidate as a scaffold ligament or tendon prosthesis if crosslink density can be increased.
In vitro and ex vivo platelet interactions with hydrophilic‐hydrophobic poly(ethylene oxide)‐polystyrene multiblock copolymers
Authors: Grainger D. W. , Nojiri C. , Okano T. , Kim S. W. 
Published: December 2004

AbstractHydrophilic‐hydrophobic multiblock copolymers synthesized from telechelic oligomers of poly(ethylene oxide) (PEO) and polystyrene (PS) have been used to study the influence of hydrophilic and hydrophobic balance on interfacial interactions of these surfaces with blood components. In vitro coagulation assays show no inherent ability of these amphiphilic surfaces to affect contact activation or coagulation factors. In vitro platelet adhesion and release reactions from rabbit platelet‐rich plasma were shown to be greatest on Biomer and PS homopolymer surfaces and least on cross‐linked PEO surfaces, with the PEO–PS block copolymers demonstrating intermediate responses. These same substrates were tested in a new low‐flow, low‐shear arterio–artery shunt system in rabbits. Whole blood occlusion times were not a direct function of hydrophilic content as both PEO and PS homopolymers and Biomer showed short occlusion times, while PEO–PS block copolymers prolonged occlusion times considerably, depending on composition. Overall, results suggest that PEO–PS block copolymers promote unique whole blood responses in contrast to homopolymer and Biomer controls which are more complex than direct correlations to bulk hydrophilic and hydrophobic contents.
Surface characterization of the cuticle of dirofilaria immitis
Authors: Bilge Fertac H. , Kadipasaoglu Kamuran A. , McCormick C. Michael , Baier Robert E. 
Published: December 2004

AbstractThe surface reactivity of the dog heartworm (D. immitis) was evaluated by comprehensive contact angle measurements and a platelet retention test. Contact angle data yielded calculated surface energy terms very similar to those previously reported for intact vascular endothelium. The platelet test revealed the native worm surface to be nonreactive, retaining fewer platelets than glass or worms whose surfaces had been modified by extraction with acid and high salt solutions. The cuticular morphology of the heartworm was studied with both light and electron microscopy, the latter coupled with ferritin‐conjugated double‐layer immunolabeling to reveal adsorbed host protein on the cuticle surfaces. Multiple attenuated internal reflection (MAIR) IR spectroscopy confirmed the general composition of this surface layer to be glycoproteinaceous. Morphological and histochemical studies confirmed and extended previous descriptions of nematode cuticle, adding ultrastructural detail on cortical, medial, and basal layers. A trilaminar membrane, apparently corresponding to a mammalian cell membrane (plasmalemma), constituted the external cortical layer as observed in high magnifications. The existence of a glycocalyx of varying thickness was demonstrated in ruthenium red‐stained sections. MAIR IR spectra showed this glycoproteinaceous film to appear, in fully hydrated samples, as a loose biological gel. Ferritin‐antibody conjugate labeling confirmed the presence of adsorbed dog albumin, dog immunoglobulin class G (IgG) and dog complement fraction 3 (C3) in the cuticular surface layer. It is likely, therefore, that D. immitis heartworms demonstrate long‐term thromboresistance at least in part due to their passive low‐surface‐energy overcoating with host proteins.
Effects of a grooved titanium‐coated implant surface on epithelial cell behavior in vitro and in vivo
Authors: Chehroudi B. , Gould T. R. L. , Brunette D. M. 
Published: December 2004

AbstractThe effects of a grooved titanium‐coated substratum on epithelial (E) cell behavior were studied in vitro and in vivo. V‐shaped grooves, 10 m̈m deep, were produced in silicon wafers by micromachining, a process which was developed for the fabrication of microelectornic components. The grooved substrata were replicated in epoxy resin and coated with 50 nm of titanium. More E cells were found attached to the grooved titanium surfaces than to adjacent smooth surfaces. In comparison to the smooth surfaces where clusters of E cells were randomly oriented, on the grooved surfaces, clusters of E cells were markedly oriented along the long axis of grooves. Grooved and smooth titanium‐coated epoxy implants were placed percutaneously in the parietal area of rats. Electron and light microscopic obsrvations indicated that E cells were tightly attached to the implant surfaces and this attachment is through basal lamina‐like and hemidesmosome‐like structures. In the grooved portion of the implant, E cells interdigitated into the grooves and had rounded nuclei. Histomorphometric measurements indicated that there was a shorter length of epithelial attachment, longer length of connective tissue attachment, and less recession in the grooved, compared to the smooth portion of implants after 7 and 10 days. These results indicate that horizontal grooves produced by micro‐machining can significantly impede epithelial downgrowth on titanium‐coated epoxy implants.
Student research award in the undergraduate, master candidate, or health science degree candidate category, 15th annual meeting of the society for biomaterials, Lake Buena Vista, Florida, April 28–may 2, 1989. Toxicity of copper‐based dental alloys in cell culture
Authors: Bumgardner Joel D. , Lucas Linda C. , Tilden Arabella B. 
Published: December 2004

AbstractThe biocompatibility of three commercial copper‐based dental casting alloys—Duracast MS, Goldent, and Trindium—three experimental copper alloys, and a control gold alloy, Modulay, were investigated. Trindium, Duracast MS, experimental alloys 1 and 2 are aluminum bronzes; Goldent is a hybrid aluminum–brass alloy; and experimental alloy #3 is a high zinc brass alloy. ASTM F813–83 Standard Practice for Direct Contact Cell Culture Evaluation of Materials for Medical Devices, a 3‐day direct‐contact cell culture regimen and atomic absorption spectroscopy were utilized for evaluating the biocompatibility of these alloys in both Waymouth's and RPMI 1640 complete media. Cellular proliferation assays, using 3H‐thymidine uptake, were also conducted in Waymouth's media. In this investigation, only the experimental alloy #3 elicited alterations in morphology and viability of the fibroblast monolayer during the ASTM and 3‐day culture tests in either media. Cell cultures exposed to experimental alloy #3 experienced copper concentrations greater than 16.0 ppm in Waymouth's and 10 ppm copper in RPMI 1640 media. Differences in the size of the cytotoxic zone around experimental alloy #3 were also observed, with the larger zone occurring in Waymouth's media. In contrast to the direct cell contact studies, all alloys caused decreases in 3H‐thymidine uptake in Waymouth's media at much reduced metal ion concentrations as compared to the controls. Thus, adverse changes in DNA synthesis occurred at much lower copper and zinc concentrations than changes in morphology and viability. Consequently, the assessment of biocompatibility is dependent on the parameters evaluated, and several parameters must be analyzed before a material may be considered biocompatible.
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

AbstractA 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

AbstractIn 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractThis 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

AbstractGlutaraldehyde (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

AbstractA 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

AbstractA 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

AbstractIn 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

AbstractMechanical 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.