bluuebunny/crossref_metadata_2025_split huggingface dataset:
Line analysis of interface layer on dentin by means of electron‐probe microanalysis
Authors: Fukushima Tadao , Horibe Takashi 
Published: December 2004

AbstractThree types of brominated methacrylates, SBPPM, BPylM, and BNEM, were synthesized. The distribution of Br, Ca, and Fe at the interface between dentin treated with the 10‐3 solution and resin containing these monomers was analyzed using an electron‐probe microanalyzer (EPMA) in order to predict the composition and thickness of the interface layer on dentin for the corresponding unbrominated methacrylates. There was no significant difference between the brominated and unbrominated methacrylates in either the bond strength to the treated dentin or in the thickness of the interface layer on dentin observed with a scanning electron microscope (SEM). The thickness determined with EPMA was equivalent to that observed with SEM. The concentration of each brominated methacrylate in the interface layer was higher than the original concentration in the resin monomers, and BNEM showed higher concentration than the others. The presence of Fe in the layer was confirmed by EPMA.
Platelet adherence and detachment: A flow study with a series of hydroxyethyl methacrylate‐ethyl methacrylate copolymers using video microscopy
Authors: Feuerstein Irwin A. , Buchan Sue M. , Horbett Thomas A. , Hauch Kip D. 
Published: December 2004

AbstractThe adhesion and detachment of platelets were studied on glass coatings of a series of copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA). Observations of the interactions of mepacrine labelled washed platelets with these surfaces from a flowing (500 s−1 wall shear rate) suspension in Tyrode's solution containing albumin and red cells were made with epifluorescent video microscopy (EVM). Total platelet adhesion, including platelets which adhere on first contact and platelets which attach temporarily before adhesion, and the number of detaching platelets were minimal for the 0 and 20% EMA copolymers, reached a maximum for the 50% EMA copolymer and showed reduced values for the 80% and 100% EMA copolymers. For the 50, 80, and 100% EMA copolymers, the adhesion values expressed, as a percentage of total contacting platelets, were not different. Albumin adsorption to these copolymers shows a continuous increase from the 0% to the 100% EMA copolymer. It is likely that the peak in platelet adhesion at the 50% EMA composition is related to: low protein adsorption on the 0 and 20% EMA copolymers, too little albumin adsorption to block adhesion on the 50% EMA copolymer, and full‐scale blocking on the 80 and 100% EMA copolymers due to greater albumin adsorption.
Novel polyfunctional silanes for improved hydrolytic stability at the polymer–silica interface
Authors: Nishiyama Norihiro , Ishizaki Tsutomu , Horie Kozo , Tomari Masato , Someya Minoru 
Published: December 2004

AbstractPolyfunctional silanes were designed to promote the formation of a stable multisilane layer on the silica surface. The hydrolytic stability of polyfunctional silanes at the interface between silica and polymeric resin was investigated using conventional tensile testing. The specimens were immersed in boiling water and a decrease was observed in the tensile bonding strength of polymeric resin against the silane‐treated silica surface as the immersion time increased. The failure mechanism changes from cohesive failure of the matrix resin to failure of the interface. The time necessary to start the interfacial failure is dependent on the silane concentration in the treating solution and the number of silicone functional groups within the silane molecules. The silane with two silicone functional groups is more stable at the interface between silica and polymeric resin than those which have mono‐ or trisilicone functional groups.
Preparation of thermo‐responsive polymer membranes. I
Authors: Nozawa Iwao , Suzuki Yosuke , Sato Shuji , Sugibayashi Kenji , Morimoto Yasunori 
Published: December 2004

AbstractTwo types of liquid crystal (LC)‐entrapped membranes, (a) polymer alloyed membranes and (b) LC‐adsorbed membranes, were investigated for the purpose of developing the drug delivery systems (DDS) with thermal stimuli responsing. Polymer alloyed membranes were obtained by polymerizing acrylic monomers in presence of LC and LC‐adsorbed membrane were obtained by adsorbing LC into porous hydrophobic polymer membrane. It was made clear from the indomethacin permeation experiments below and above the gel‐liquid crystal phase transition temperature of the LC that the extent of thermo‐sensitivity for LC‐adsorbed membranes was greater than that for the alloyed membrane. The permeability ratio (38°C vs. 32°C) was found to be about 120 with the LC‐adsorbed membrane. It was suggested from the results that the LC‐adsorbed membrane was one of the useful candidates as a thermo‐responsive system for DDS.
A laboratory model to quantitate the resistance of collagen vascular grafts to biodegradation
Authors: Megerman Joseph , Reddy Esphiran , L'Italien Gilbert J. , Warnock David F. , Abbott William M. 
Published: December 2004

AbstractRecent reports have shown that despite extensive preclinical testing, vascular grafts of biological origin undergo severe biodegradation and aneurysm formation after two or more years of implantation in man. The purpose of this study was to develop a laboratory model to quantitate and correlate the stability of crosslinked collagen grafts in vitro and in vivo. This resistance to biodegradation was assessed by measuring changes in suture pullout force and sample weight in response to controlled digestion with bacterial collagenase, in 0.5‐cm‐long cylindrical graft segments (chemically processed bovine carotid artery and human umbilical cord vein) that were implanted in the rat subcutis for 2 to 12 weeks. Scar tissue was removed from the explants by brief enzymatic digestion, a process that was inhibited when graft segments had become infected. Changes in dry weight were more consistent than were changes in wet weight; drying the graft segments had no effect on their degradation in vivo or in vitro. Intact cylindrical rings suffered somewhat less damage than did opened, flattened cylinders. Graft degradation increased markedly with implantation time, and was detected after only 3 weeks. We conclude that the rat subcutis model, when combined with controlled enzymatic digestion, first to remove scar tissue and then to challenge structural integrity, provides an accelerated assay by which to predict the stability of collagen vascular grafts.
Use of a phosphophoryn‐Ca+2‐collagen composition that mimics a mineralization front in unicortical defects in long bones
Authors: Sauk John J. , Van Kampen Craig L. 
Published: December 2004

AbstractThe present study was designed to ascertain if dynamic ionic matrices that mimic the mineralization front could be used as active scaffolds for bone repair. Dentinal phosphophoryn calcium salts were extracted from unerupted bovine dentin using chatopic buffers and EDTA. The phosphophoryns were subsequently isolated following precipitation with CaCl2. The phosphophoryn‐Ca+2 salts were then mixed with pepsin solubilized bovine skin collagen and lyophilized into hardened sponges. Three groups of 4 beagle dogs were employed such that one leg served as an experimental test site for a mechanical wound, while the contralateral leg served as a control. Animals were sacrificed at 1, 3, and 6 month intervals. The test specimens were harvested, fixed, and processed for routine histology, examined with image histomorphometric analysis, and scored. Tabulation of these data indicated that phosphophoryn‐Ca+2‐collagen enhances the repair of mechanically formed osseous defects in the distal femur of beagle dogs. This enhanced rate of bone repair was manifest by earlier filling of bony voids with osteoid and trabecular bone. Eventually, this process was followed by recortification of the surface defects. These data suggest that components derived from a mineralization front may influence bone formation in unicortical defects within long bones.
Effects of fibroblasts and basic fibroblast growth factor on facilitation of dermal wound healing by type I collagen matrices
Authors: Marks Michael G. , Doillon Charles , Silvert Frederick H. 
Published: December 2004

AbstractHealing of large open dermal wounds is associated with decreased values of the tensile strength even up to 6 months postwounding. Results of previous studies have shown that healing is facilitated in the presence of a type I collagen sponge by promoting deposition of newly synthesized large‐diameter collagen fibers parallel to the fibers of the sponge. In this study healing is evaluated in dermal wounds treated with a collagen sponge seeded with fibroblasts or coated with basic fibroblast growth factor (bFGF).Experimental results indicate that the presence of a collagen sponge results in increased wound tensile strength and increased collagen fiber diameters in the upper dermis 15 days post‐wounding in an excisional guinea pig dermal wound model. In comparison, dermal wounds treated with collagen sponges seeded with fibroblasts or coated with bFGF showed increased tensile strengths 15 days postimplantation and increased degree of reepithelialization. These results indicate that fibroblast seeding and bFGF coating in conjunction with a type I collagen sponge matrix facilitate early dermal and epidermal wound healing.
In vitro degradation of a poly(ether urethane) by trypsin
Authors: Bouvier M. , Chawla A. S. , Hinberg I. 
Published: December 2004

AbstractIn vitro enzymatic degradation of nonporous films of segmented poly(etherurethane) (Pellethane 2363–80AE) was investigated by incubating the biomaterial in concentrated trypsin solutions for 5 months at room temperature. Chemical degradation of films was monitored by surface analysis techniques such as Fourier transform infrared spectroscopyattenuated total reflectance and electron spectroscopy for chemical analysis. This latter technique proved to be much superior in detecting chemical changes. Extraction of films with methanol and characterization of the extracts by gel permeation chromatography revealed the presence of low‐molecular‐weight polymers. Results have shown that trypsin has the ability to induce degradation in PEU, the soft segment being most affected, particularly the CH2O bond of the either linkages.
The stabilization of fibrillar collagen matrices with 3,4‐dihydroxyphenylalanine
Authors: Gade Jay N. , Fellman Jack H. , Peter Bentley J. 
Published: December 2004

AbstractPepsin‐treated type I collagen fibrils were reconstituted by warming to 37°C in the presence of DOPA at a concentration of 1 × 10−3M. Following a 1‐1.5‐h lag period tdhe “gels” became progressively stabilized as indicated by an inability to disperse these at 0°C. Following 24 h of incubation at 37°C, the DOPA‐collagen gels were insoluble in dilute acetic acid even under denaturing conditions. The effect on both gel stability and solubility was concentration‐dependent and was maximum at 1 × 10−3M. Gel solubility changes were significant, with the greatest change occurring between concentrations of 3.1 × 10−5M. DOPA exposure did not alter the fibrillar banding pattern seen at the electron microscopic level. Collagen felts prepared by lyophilization of DOPA‐collagen gels demonstrated an increase in shrinkage temperature which after 24 h exceeded that of rat tail tendon. Preformed collagen felts incubated for 24 h in the presence of 1 mM DOPA also had a greatly increased shrinkage temperature. Pepsin‐treated collagen control felts were consistently unstable at 37°C. The tensile properties of DOPA‐collagen felts were altered with respect to control felts in a time dependent manner. The wet tensile strength increased to four times that of control after 3 days of incubation at 37°C. Matrix extensibility initially increased to 1.5 times that of control felts after 4 days of incubation at 37°C, but decreased to below control values following 6 additional days of incubation. These properties suggest that DOPA may be useful as a stabilizing agent of collagen biomedical prostheses.
Dental implant materials. I. Some effects of preparative procedures on surface topography
Authors: Smith D. C. , Pilliar R. M. , Chernecky R. 
Published: December 2004

AbstractThe effect of different treatments for preparing implant materials was examined by scanning electron microscopy and by contact angle measurements. The materials examined were Ti6Al4V alloy, Co‐Cr‐Mo alloy, Al2O3, and synthetic hydroxyapatite. Samples were prepared with solid or porous surfaces of these materials. These were detergent‐cleaned and then either autoclaved (steam sterilization), radiationsterilized, nitric acid‐etched, or plasmacleaned. The results of wettability studies indicated marked changes in surface energy corresponding to the different preparation methods, and differences in surface morphology were also observed. These differences could have significant consequences onin vivoimplant behaviour as mediated by tissue‐implant interactions.
Student research award in the undergraduate, Master candidate category, or health science degree candidate category, 17th annual meeting of the society for biomaterials, scottsdale, AZ may 1–5,1991. Characterization of the interface in the plasma‐sprayed HA coating/Ti‐6Al‐4V implant system
Authors: Filiaggi M. J. , Coombs N. A. , Pilliar R. M. 
Published: December 2004

AbstractThe successful use of plasma‐sprayed hydroxyapatite (HA) coatings on Ti‐alloy implants for implant‐to‐bone fixation requires strong adherence of the ceramic coating to the underlying metal substrate. In this study, the metal‐ceramic interface was evaluated using mechanical, chemical, and structural characterization methods. Evaluations of an HA‐coated Ti‐6A1‐4V implant system using a modified short bar technique for interfacial fracture toughness determination revealed relatively low fracture toughness values. Additionally, conventional tensile bond strength testing indicated much lower values than previously reported. Using high resolution electron spectroscopic imaging, evidence of chemical bonding was revealed at the plasmasprayed HA/Ti‐6AI‐4V interface, though bonding was primarily due to mechanical interlock at the interface. This study illustrates the benefits of, and the need for, a multilevel approach to evaluate and improve these plasma‐sprayed ceramicme tai subst rate interfaces.
Formation of 4,4′‐methylenedianiline in polyurethane potting materials by either γ‐ray or autoclave sterilization
Authors: Shintani Hideharu , Nakamura Akitada 
Published: December 2004

AbstractIn this experiment, we found that a potential carcinogen, 4,4′‐methylenedianiline (MDA), was produced from γ‐ray irradiated potting materials, medical thermosetting polyurethane (PU). γ‐Ray irradiated PUs were immersed in either methanol or in equine serum. The time course of MDA leached from the potting materials and other variables were compared. A significant relationship was noted between the amount extracted and the rigidity of the potting material. The accumulated amount of extracted MDA (a few ppm in the original sample) increased with increasing irradiation dose by a second‐order equation. One sample indicated reduced MDA elution after irradiation in the early stage. MDA extraction with serum was 82–87% that with methanol. In one case, MDA leaching into serum in the early stage was higher than that into methanol. Autoclave sterilization did not promote MDA formation, thus indicating that autoclaving would be preferable.
The effect of aluminum ions and sorbitol on collagen and skin: A thermally stimulated current spectroscopy study
Authors: Gervais‐Lugan M. , Haran R. , Lamure A. , Lacabanne C. 
Published: December 2004

AbstractThe influence of aluminum ions introduced either directly or with sorbitol, in collagen and skin, has been investigated by Thermally Stimulated Current/TSC spectoscopy. The intramolecular mobility of collagen has been found to be significantly reduced by aluminum ions. The substitution of water molecules by aluminum ions on intramolecular hydrophilic sites is suggested to be responsible for this evolution. The presence of sorbitol minimizes this effect. The intermolecular mobility of collagen is decreased upon introduction of aluminum ions introduction of aluminum ions in presence of sorbitol. This result can be explained by the interaction of sorbitol‐aluminum entities with the telopeptidic regions of collagen molecules. In skin samples, the intra‐ and intermolecular mobilities are restored due to the combined actions of sorbitol and noncollagenous proteins and other macromolecules.
Formation of a multilayer cellular lining on a polyurethane vascular graft following endothelial cell sodding
Authors: Williams Stuart K. , Carter Thomas , Park Pauline K. , Rose Deborah G. , Schneider Timothy , Jarrell Bruce E. 
Published: December 2004

AbstractSmall‐diameter (<6 mm) clinically available vascular grafts often fail due in part to the inherent thrombogenicity of artificial polymers. Transplantation of endothelial cells onto the lumen of these vascular grafts has been suggested as one method to overcome this thrombogenicity. We have developed a compliant polyurethaneurea (PEUU) 4‐mm graft with a luminal surface modified by a glow discharge gas plasma. Autologous microvessel endothelial cells were isolated from canine falciform ligament fat, were transplanted onto the luminal surface of the grafts using an intraoperative isolation and sodding technique, and both endothelial‐cell‐treated and non‐cell‐treated grafts were placed as bilateral carotid interposition grafts in a canine model. After 5 weeks of implantation, explanted control (non‐cell‐treated) grafts exhibited a deposition of platelets, white cells and fibrin characteristic of a thrombogenic surface. MVEC sodded grafts exhibited a multicellular lining within but distinct from the lumen of the PEUU graft. The blood‐contacting surface of this lining exhibited an antithrombogenic endothelial cell monolayer. We suggest that the PEUU graft supported the initial deposition of MVEC and development of an endothelial cell lining. During the 5 weeks of implantation this lining continued to proliferate and detached from the PEUU graft substratum. The final neocellular lining exhibited a luminal diameter and histological features similar to a native artery.
Microhardness measurements of renal calculi: Regional differences and effects of microstructure
Authors: Zhong P. , Chuong C. J. , Goolsby R. D. , Preminger G. M. 
Published: December 2004

AbstractMicrohardnesses of five types of renal calculi: calcium apatite (82.5%)/magnesium ammonium phosphate hydrogen (lo%)/ calcium oxalate monohydrate (7.5%); calcium apatite (95%)/calcium oxalate monohydrate (5%); magnesium ammonium phosphate hydrogen (90%)/calcium apatite (10%); calcium oxalate monohydrate (85%)/calcium apatite (15%); and cystine (100%) were measured. Using Knoop and Vickers indenters the effects of chemical composition and microstructure on the microhardness measurement were assessed. Calcium oxalate monohydrate, magnesium ammonium phosphate hydrogen, and cystine stones, without apparent structure pattern, showed neither regional nor directional differences in their microhardness. In contrast, calcium apatite stones, with distinctly concentric laminae structure, showed regional variations which were correlated with the chemical composition of stone constituents. Scanning electron microscopy of the indenter impressions were taken to help in interpreting the directional dependence in Knoop hardness measurements with respect to the microstructure of the calculi. Vickers measurements showed the crystalline stones were isotropic within a layer. Combined results of Knoop and Vickers measurements indicate that the anisotropic Knoop hardness readings seen in the laminated regions were structural but not material‐based. Implications of the results for the fragmentation of renal calculi in extracorporeal shock wave lithotripsy are discussed. © 1992 John Wiley & Sons, Inc.
Tensile testing of tubular vascular grafts produced by thermal compression fusion of flat collagenous materials
Authors: Wyler A. , Markus R. T. 
Published: December 2004

AbstractA novel process of fusion bonding for the production of vascular grafts has been investigated. This process, based on the application of pressure and heat in a sophisticated way, has been used for the bonding of the longitudinal edges of flat dermal sheep collagen into tubular forms. The method produces continuous overlapping joints which are expected to overcome the problem of coagulation, as occurs in grafts produced by suturing. The values of the measured shear strength of the bond vary from 750 ± 30 kPa to 940 ± 32 kPa, depending on tube diameter and overlap length (n = 5). These values are much higher than calculated values of the stress in thin‐walled tubes caused by a high static blood pressure, indicating a high safety factor for the fusionbonded vascular grafts. © 1992 John Wiley & Sons, Inc.
Antisera binding onto metals immersed in human plasma in vitro
Authors: Wälivaara Bengt , Askendal Agneta , Elwing Hans , Lundström Ingemar , Tengvall Pentti 
Published: December 2004

AbstractTitanium (Ti), silicon (Si), silver (Ag), vanadium (V), gold (Au), and chromium (Cr) surfaces were made hydrophilic by radiofrequency plasma treatment. The binding of antifibrinogen (a‐fib) and anti‐high‐molecular‐weight kininogen (a‐HMWK) after incubation of surfaces in 10% human blood plasma was investigated with ellipsometry. Ti and Si surfaces bound a‐HMWK but no detectable amounts of a‐fib, whereas the other metals bound both types of antisera. Protein adsorption in a fluid gradient produced under a convex lens indicated that the small deposition of a‐fib on Ti and Si surfaces is probably a result of protein displacement. This displacement was not evident a t lens positions simulating low plasma concentrations where large amounts of a‐fib adsorbed. Surfaces washed sequentially in trichloroethane, acetone, and ethanol produced more hydrophobic surfaces and resulted in slower rates of a‐fib displacement. These studies would indicate that some metals form complexes with specific plasma proteins or, alternatively, that different metals may bind equal amounts of plasma proteins which express differing antigenicities to‐ward their surroundings. © 1992 John Wiley & Sons, Inc.
Decreased tissue reaction to bioprosthetic heart valve material after L‐glutamic acid treatment. A morphological study
Authors: Grabenwöger Martin , Grimm Michael , Eybl Elisabeth , Leukauf Christian , Müller Mathias M. , Plenck Hanns , Böck Peter 
Published: December 2004

AbstractDegenerative alterations of two different glutaraldehyde (GA)‐fixed bioprosthetic heart valve materials were investigated in subcutaneous rat implants: Bovine pericardium, prepared according to clinically used bioprosthetic heart valve material (BHV) was compared to alternatively preserved pericardium (APHV), which was fixed in GA and treated with L‐glutamic acid. Following 63 days of subcutaneous implantation, calcification of APHV implants was significantly lower as compared to BHV implants (13 ± 6 versus 158 ± 18 μg Ca/mg dry weight tissue; p ± 0.05). In BHV implants ultrastructural investigations showed nucleation of plate‐shaped hydroxyapatite crystals at the surface of collagen fibrils and in remnants of connective tissue cells; no signs of calcification could be detected in APHV implants. The time‐course of the inflammatory reaction was determined by quantification of immunohistochemical stained mononuclear host‐cells invading the implants. In both preparation groups inflammatory reaction reached maximum 42 days after implantation. However, infiltration rate of inflammatory cells was markedly decreased in APHVs as compared to BHVs (p ≤ 0.05). © 1992 John Wiley & Sons, Inc.