bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of extraction replicas in scanning electron microscopy for the elemental analysis of marginal seals
Authors: Witcomb M. J. , Jodaikin A. , Grossman E. S. 
Published: December 2004

AbstractElemental analysis of marginal seal material on 20 bulk samples of occlusally restored teeth have shown that, generally, more elements were detected in the seal material analyzed on the bulk restoration or fractured tooth surfaces than when such material was extracted using a nitrocellulose replica prior to analysis. No mercury was detected in any of the extracted seal material and only three of the replica specimens contained silver. This implies that the technique of using extraction replicas to remove material from the amalgam‐tooth interface for subsequent x‐ray microanalysis can provide an accurate elemental composition. The details of fabrication and the advantages of using high resolution nitrocellulose replicas for extracting marginal seal material from teeth for subsequent x‐ray microanalysis are described.
A new reconstitued connective tissue matrix: Preparation, biochemical, structural and mechanical studies
Authors: Aprahamian Marc , Lambert Alain , Balboni Ginette , Lefebvre Françoise , Schmittaeusler Roland , Damge Christiane , Rabaud Michel 
Published: December 2004

AbstractA fibrinogen derivative generated by thrombin was reacted with elastin to yield a new addition product or adduct between the two proteins. Addition of fibronectin, and then of collagen, did not interfere with the basic elastin‐fibrinogen reaction and conferred the qualities of an artificial connective tissue to the product. Biochemical, structural and biomechanical aspects of the new matrix were studied. Aprotinin, heparin, thiomersal, and thiourea did not inhibit the main reaction; indeed, some of these ingredients improved the matrix cohesion. Scanning electron microscopy showed the genesis of a true network whose meshes were more reticulated by the addition of thiourea. Biomechanical studies, i.e., strength and elasticity showed the thiourea matrix to be the strongest. These intrinsic properties suggest the product could have biological and clinical applications.
The influence of postcuring on the fracture properties of photo‐cured dimethacrylate based dental composite resin
Authors: Cook Wayne D. , Johannson Melinda 
Published: December 2004

AbstractThe dependence of the fracture behavior of photocured dimethacrylate‐based composite resins on the matrix crosslink density (varied by postcuring at various temperatures) was investigated. In general, the fracture toughness (Klc) was increased by posfcuring as has been observed for epoxy–amine networks. The flexural and diametral tensile strength was also raised by postcuring. Calculation of the inherent flaw size (a0) from these properties produced conflicting dependencies on the state of cure. It is suggested that improved wear resistance and incisal edge strength of dental composite resin restoratives may be achieved by increased degree of cure.
The enzymatic degradation of polymers in vitro
Authors: Smith R. , Oliver C. , Williams D. F. 
Published: December 2004

AbstractSpecimens of 14C‐labeled poly(ethylene terephthalate), nylon 66, and poly(methyl methacrylate) have been synthesized and exposed, in vitro, to a number of enzyme solutions. Poly(ethylene terephthalate) was found to be affected by esterase and papain, although in different ways, but not by trypsin or chymotrypsin. Nylon 66 was unaffected by esterase but degraded by the other three. Poly(methyl methacrylate) was not affected by any of these enzymes. This indicates that some nominally stable polymers are susceptible to degradation by enzymes under some circumstances. The amount of degradation is small, but could have significant sequelae should it be reproduced in vivo.
The evaluation of the interface between bone and a bioceramic dental implant
Authors: Gatti A. M. , Zaffe D. , Poli G. P. , Galetti R. 
Published: December 2004

AbstractMethods for evaluating the interface between bone and an experimental dental implant have been analyzed. The material studied was a titanium implant coated with a mixture of alumina and titanium dioxide by means of a plasma‐jet system with the dog as the animal model. The evaluations were made on two levels: (1) in vivo, by analyzing radiographs of the peri‐implant zone with a video display computer (2) in vitro, after explantation, by analyzing vertical and horizontal sections of the sample with an optical and a scanning electron microscope, and by a video display computer analysis of the microradiographs of these sections.
Competition between adsorbed fibrinogen and high‐molecular‐weight kininogen on solid surfaces incubated in human plasma (the vroman effect): Influence of solid surface wettability
Authors: Elwing Hans , Askendal Agneta , Lundström Ingemar 
Published: December 2004

AbstractThe influence of the surface energy on the competition between fibrinogen and high‐molecular‐weight kininogen has been studied with the use of a recently described wettability gradient method. One finding is that the decrease in the antifibrinogen binding on plasma incubated gradient surfaces was not associated with an increase in anti‐HMWK binding at all parts of the gradient surfaces.
Adsorbed behavior of spin‐labeled silane coupling agent on colloidal silica studied by electron spin resonance
Authors: Nishiyama Norihiro , Katsuki Hirokazu , Horie Kozo , Asakura Tetsuo 
Published: December 2004

AbstractThe adsorption mechanism of silane coupling agent on the colloidal silica surface is studied with spm‐labeled silane coupling agent using ESR method. The density of the adsorbed silane molecules was determined to be approximately 1.5–2 molecules per 100 Å2 of the silica surface in 95% ethanol solution. In addition, ESR signal of spin‐labeled agent adsorbed on the colloidal silica surface was composed of two components; slow component attributable to the agents adsorbed directly on the SiOH groups of the silica surface through hydrogen bond formation and rapid one attributable to the agents interacted with such adsorbed silane molecules.
Viscoelastic behavior of polyurethane vascular prostheses
Authors: How T. V. , Annis D. 
Published: December 2004

AbstractA method of evaluating the in vitro viscoelastic properties of microfibrous Biomer poly(ether‐urethane‐urea) vascular prostheses is outlined. Quasi‐static and dynamic tests were carried out on Biomer grafts of diameter between 3.4 mm and 3.8 mm and wall thickness between 0.25 mm and 0.55 mm. It is shown that the quasi‐static compliance of a Biomer graft may be determined from an equation relating transmural pressure, radius, and longitudinal strains in terms of the graft dimensions and material constants. The dynamic compliance spectra were evaluated as a function of the longitudinal and circumferential strains and temperature. Although the ratio of dynamic compliance to quasi‐static compliance was linearly related to the logarithm of frequency it was not significantly affected by strains or temperature over the relevant ranges studied. Employing the usual assumptions of linear isotropic incremental elastic theory the dynamic elastic and viscous moduli were calculated as a function of frequency. Biomer grafts were more viscous than canine carotid and femoral arteries, especially at the higher frequencies. The variation in the ratio of dynamic to static incremental modulus with frequency was similar to that observed in the femoral arteries by Bergel (J. Physiol., 156, 458–469 (1961)).
Bonding behavior between two bioactive ceramics in vivo
Authors: Kitsugi Toshiaki , Yamamuro Takao , Nakamura Takashi , Kokubo Tadashi , Takagi Masataka , Shibuya Takehiro , Takeuchi Hiroyasu , Ono Mikiya 
Published: December 2004

AbstractThe purpose of this study is to examine the chemical bonding mechanism between bioactive ceramics in vivo. Two experiments were performed. In the first experiment, rectangular specimens (5 mm × 5 mm × 25 mm) of apatite‐wollastonite containing glass‐ceramics (designated A 7middot; W — GC) were used. In the second experiment, plates (15 mm × 10 mm × 2 mm) of A · W — GC and three types of hydroxyapatite (designated HA) were used. The sintering temperature and porosity (%) of the three types of HA were 1200°C (0.4%), 1000°C (4.8%), and 800°C (45%), respectively. In each experiment, two pairs of specimens of identical material, one bound with silk thread, the other not bound, were implanted subcutaneously into rats. In the first experiment, bonding of only bound specimens was observed at 3 and 6 months after implantation. The observation of interface by SEM‐EPMA showed that a Ca — P‐rich layer formed between the two specimens. In the second experiment, bonding of both bound and nonbound A · W — GC produced identical results 1 month after implantation. For HA sintered at 800°C and 1000°C, bonding was observed in every specimen. This phenomenon might be caused by the chemical change of hydroxyapatite occurring at different sintering temperatures. The Ca — P‐rich layer was observed between two plates. These results suggest that self‐repair of bioactive ceramic is possible under certain conditions.
Short‐term cell‐attachment rates: A surface‐sensitives test of cell–substrate compatibility
Authors: Vogler E. A. , Bussian R. W. 
Published: December 2004

AbstractMechanisms of cell deposition from a sessile liquid phase and adherence to various plastic substrates have been investigated by measurement of short‐term (<120 min) cell‐attachment rates. Sigmoidal attachment‐rate curves were fit with a three‐parameter variant of a logistic equation to quantify parameters related to initial rate and equilibrium‐adherence. For substrates on which cell adhesion was low, initial rates were estimated from slopes of linear bestfit equations. Average variations in adherence parameters for three cell lines, MDCK (epithelioid), VERO, and AHL‐1 (fibroblastic) to tissue‐culture grade polystyrene dishes were less than 10% (standard‐error‐of‐mean/mean × 100) over extended periods of more than two months, so that attachment measurements could be repetitively applied with the same cell stocks continuously subcultured in the laboratory. Developed techniques were applied to a variety of plastics and the results tabulated. Comparison of adherence parameters for ionomer and polyethylene films, both with and without adsorbed fetal‐bovineserum proteins, demonstrated that surface carboxyl groups were important in protein adsorption and cellular adherence. Attachment rates of MDCK to polystyrene were dependent on starting cell number whereas equilibrium adherence did not vary significantly over a wide range of inoculum concentrations. It was concluded from theoretical considerations that initial rates of MDCK attachment were sensitive to and dependent on electrostatic barriers to formation of close substrate contacts whereas equilibrium‐adherence levels were controlled by short‐range forces such as interfacial energies and formation of receptor‐ligand complexes.
Controlled release using a new bioerodible polyphosphazene matrix system
Authors: Laurencin C. T. , Koh H. J. , Neenan T. X. , Allcock H. R. , Langer Robert 
Published: December 2004

AbstractPolyphosphazenes possess polymer backbones consisting of nitrogen and phosphorous formally separated by alternating single and double bonds. Their potential for biomedical applications stems from the fact that polymers with a wide array of properties can be synthesized using the same starting compound, poly(dichlorophosphazene), through changes in side chain substituents, and that many of these compounds synthesized have been found to biodegrade to harmless products. In this article, studies of a novel monolithic bioerodible polyphosphazene matrix system for controlled drug delivery are presented. Poly(imidazole methylphenoxy) phosphazene is synthesized and shown to be bioerodible. The versatility of drug delivery devices fabricated using this polymer is shown through studies of release of macro‐molecules and low molecular weight drugs. Initial histological evaluations of this particular polyphosphazene are also presented.
Newly made antibacterial braided nylon sutures. I. In vitro qualitative and in vivo preliminary biocompatibility study
Authors: Chu C. C. , Tsai W. C. , Yao J. Y. , Chiu Sindy S. 
Published: December 2004

AbstractA new type of braided nylon thread with a silver compound coating was made for the purpose of designing a biocidal suture material. The study used standard bacterial culture techniques to evaluate the antibacterial prop‐erty of the new Ag‐coated nylon thread. Seven types of bacterial species were tested; S. aureus, E. coli, P. aeruginosa, K. pneumoniae, S. dysenteriae, S. maruslene, and P. mirabilis. The commercial size 2/0 Nurolon suture from Ethicon served as the control. A weak direct current ranging from 0.4–400 μA was applied to the specimens to examine whether the biocidal property of silver could be enhanced by current. The antibacterial property was evaluated by the width and sterility of the clear zone in the bacterial culture plates. It was found that the new nylon thread exhibited very good to moderate bactericidal property toward these seven bacterial species. P. aeruginosa was the most sensitive species, while P. mirabilis was the least sensitive one. Application of direct current through the Ag‐coated specimens positively enhanced their antibacterial property and the degree of enhancement depended on the direct current level. The material also exhibited an antibacterial property toward well‐established bacterial colonies, but the effect was less strong than the case when direct current was applied simultaneously with incubation. Silver ions released from the coated nylon thread were responsible for the observed antibacterial property; and the application of a weak direct current to the material enhanced this effect. A preliminary biocompatibility study of this new material in rat gluteal muscle indicated that the new material caused less inflammatory reaction than the control Nurolon suture up to 60 days after implantation.
Use of chemically purified and cross‐linked bovine pericardium as a ligament substitute
Authors: Chvapil Milos , Gibeault David , Wang Ti‐Fen 
Published: December 2004

AbstractThis study tested the reaction of a periarticular tissue to implanted pericardial membrane, substituting a segment of patellar ligament. Bovine pericardium was chemically purified and cross‐linked with monomeric glutaraldehyde under pH, temperature and time conditions minimizing the polymerization of the cross‐linking agent. Eight rats had both knee joint patellar ligaments excised. One side served as a control (simple suture), the other dissected ligament was replaced with a strip of pericardium. After 18 days and 12 weeks the dissected ligaments were analyzed by morphological methods. An unexpected fast ingrowth of cells and vessels was observed at 18 days. At 12 weeks new collagen deposits within pericardial patch were seen with striking biodegradation of the implant. Thus, using a new method of cross‐linking the collagenous matrix with glutaraldehyde we see no evidence of glutaraldehyde cytotoxicity, as documented by our previous work.
Characterization of the tissue proliferated at the blood interface of carbon/ceramic composites
Authors: Chignier Elza , Guidollet Jeanine , Dureau Georges , Grousson Brigitte , Buttazzoni Bernard , Louisot Pierre , Elloy Rosy 
Published: December 2004

AbstractThe present study focuses on cell adhesion/differentiation and material stability of surfaces of the three carbon/ceramic composites implanted in intra‐atrial position in dogs for 1 year. Before implantation their surface was characterized by scanning electron microscopy. After harvesting, the tissue proliferated on the blood interface was examined by histology, scanning, and transmission electron microscopy, wavelength dispersive and x‐ray spectrometry, electrophoretic and enzymatic characterization of glycosaminoglycans (GAGs) which were compared to endocardiac tissue as control samples. One year after implantation, the pattern of GAGs in the newly developed tissue was characterized by: (1) a constant increase of the total GAGs present on all carbon composites, (2) a significant increase of dermatan sulfate (p < 0.05), (3) a significant increase of chondroitin sulfate (p < 0.05), (4) a significant decrease of heparan sulfate in Group 1, whereas this GAG fraction was increased in Groups 2 and 3. Cellular surface differentiation towards endothelial‐like cells occurred in places particularly in groups 1 and 3, whereas only fibrous tissue was found covering the implants in Group 2. Fibroblastic cells with dense intracellular deposits, which produced emission of Si, Ca, and C energy as well as extracellular lipidic containing inclusions were observed. The macromolecular modifications were associated with (1) the absence of endothelial lining, (2) the migration of carbon and silicon particles, and (3) the occurrence of calcifications and lipidic inclusions. These results suggest that the relative smoothness of these materials could be responsible for the development of a tissue that did not adhere to the biomaterial, indicating that cell adhesion and functional differentiation are in intimal relationship with the physical‐chemical structure of the material surface.
Molecular and supramolecular structure of adsorbed fibrinogen and adsorption isotherms of fibrinogen at quartz surfaces
Authors: Nygren Håkan , Stenberg Manne 
Published: December 2004

AbstractThe adsorption of fibrinogen to quartz surfaces was measured by ellipsometry, ELISA, and electron microscopy. The initial adsorption at low concentrations was diffusion rate limited as determined by the ELISA and by counting the number of adsorbed molecules at electron micrographs. From ellipsometry, ELISA, and electron microscopy measurements it was found that the surface concentration of adsorbed fibrinogen increased continuously over four decades in bulk concentration of fibrinogen. At a hydrophilic quartz surface a plateau level of the adsorption isotherm was found at a surface concentration of 0.1 pmol/cm2 where the adsorbed molecules had a mean intermolecular distance of 10 ± 5 nm between neighbors. At higher surface concentrations the molecules were densely packed and formed a layer where single molecules could not be identified. Adsorbed fibrinogen showed different structure at hydrophobic and hydrophilic quartz surfaces. At a hydrophilic surface, the fibrinogen molecules appeared as a 46 nm nodose rod consisting of 6–7 nodes with a diameter of 4 nm. At a hydrophobic surface, the molecule appeared as a binodular or trinodular rod with a node diameter of 5–9 nm, connected with a thin filament to form a 40‐nm rod. Adsorption from higher concentrations of fibrinogen in solution resulted in adsorbed spheric structures with a diameter of 18–24 nm at the hydrophobic surface and in end‐to‐end polymers at the hydrophilic quartz membrane.
Physical and hydrodynamic factors affecting erythrocyte adhesion to polymer surfaces
Authors: Chang G. , Absolom D. R. , Strong A. B. , Stubley G. D. , Zingg W. 
Published: December 2004

AbstractUsing a flow cell design which ensures fully developed laminar flow, the influence of various hydrodynamic and physical factors in determining the extent of erythrocyte adhesion to various polymer surfaces has been examined. Specifically we have investigated the effect of exposure time, flow rate, erythrocyte concentration, and substrate surface tension on the extent of erythrocyte adhesion. The results indicate: (1) the extent of erythrocyte adhesion is most extensive on the more hydrophobic surfaces; (2) the rate of adhesion is higher on the more hydrophobic surfaces; (3) saturation coverage occurs after 7–10 min of exposure to the erythrocyte suspension for all substrates examined. No „lag‐time”︁ in the onset of adhesion was observed; (4) The level of saturation depends on the bulk erythrocyte concentration, increasing with increasing cell concentration; (5) the extent of adhesion decreases with an increase in flow rate; and (6) substrate surface defects such as roughness have a major effect on the pattern of erythrocyte adhesion.
AES analysis of stainless steel corroded in saline, in serum and in vivo
Authors: Zabel David D. , Brown Stanley A. , Merritt Katharine , Payer Joe H. 
Published: December 2004

AbstractAuger electron spectroscopic (AES) studies were conducted to examine the surface film of stainless steel specimens which had been subjected to passive and anodic corrosion in vitro and in vivo. Anodic corrosion was accelerated by the application of a +500 mV (SCE) potential for 30 minutes. Experiments performed in 0.9% saline indicated little alteration in the nature of the surface film compared to a freshly prepared control specimen. Auger analysis of specimens in 10% serum or in vivo revealed that passive film thickness was dependent on the corrosive environment. The films of specimens immersed under freely corroding conditions in 10% serum or in vivo were similar to the control film. Accelerated corrosion performed in 10% calf serum resulted in significant film thickening. The thickest films were from accelerated corrosion in vivo. The mechanism for the altered surface films produced by corrosion in vivo or in serum as compared to saline needs to be investigated further.
Hydrophilic microporous polyurethane versus expanded PTFE grafts as substitutes in the carotid arteries of dogs. A limited study
Authors: Martz Hugues , Paynter Royston , Slimane Saidi Ben , Beaudoin Gilles , Guidoin Robert , Brzone Juan , Simhon Haim Ben , Satin Richard , Sheiner Nathan 
Published: December 2004

AbstractA novel, microporous, hydrophilic polyether urethane‐urea (PEUU) vascular graft was compared with expanded PTFE in the canine carotid artery. At implantation times ranging from 4 h to 6 months, all the PEUU grafts were found to be occluded while of the PTFE grafts, only those implanted for 1 week and 6 months were blocked. Histopathological analysis of the explanted grafts and their capsules revealed an on‐going inflammatory reaction at the anastomotic sites of the PEUU grafts.
Use of an enzyme linked immunosorbent assay (ELISA) for quantification of proteins on the surface of materials
Authors: Merritt Katharine , Edwards Christopher R. , Brown Stanley A. 
Published: December 2004

AbstractThis study demonstrates the usefulness of an enzyme linked immunosorbent assay (ELISA) for detection and quantification of protein on the surface of materials. Bovine serum albumin (BSA) and bovine gamma globulin (BGG) were the proteins used. Titanium and stainless steel were the materials tested. The proteins were detected with the use of rabbit antiserum specific for BSA and for BGG. This reaction was quantitated by the use of horseradish peroxidase conjugated goat anti‐rabbit gamma globulin. The technique is described in detail. The technique was demonstrated to be suitable for quantitation of protein from 0.01 mg/mL to 0.1 mg/mL on the surface of 3 mm × 10 mm materials. The technique was also demonstrated to be suitable for determining the surface area of solid materials. It is a simple technique and suitable for most biomaterials laboratories.