bluuebunny/crossref_metadata_2025_split huggingface dataset:
The minimum surface fibrinogen concentration necessary for platelet activation on dimethyldichlorosilane‐coated glass
Authors: Park K. , Mao F. W. , Park H. 
Published: December 2004

AbstractAlbumin and fibrinogen were competitively adsorbed onto dimethyldichlorosilane‐coated glass (DDS‐glass) and platelet activation was examined as a function of the surface fibrinogen concentration. The weight ratio of albumin to fibrinogen in the adsorption solution was varied from 10 to 700. Platelet activation was quantitated by the area and circularity of spread platelets. When the DDS‐glass was coated with albumin alone, platelets were only contact adherent and could not spread at all. After competitive adsorption of fibrinogen and albumin, however, platelets were able to spread on the surface. Platelet activation increased linearly as the surface fibrinogen concentration increased up to 0.02 μg/cm2. Platelets were able to activate fully if the surface fibrinogen concentration was 0.02 μg/cm2 or higher, even though the surface was dominated by albumin. It appears that platelets can activate fully as long as only a small fraction (2–15%) of the surface is covered with tightly bound fibrinogen.
Cytotoxicity of a BIS‐GMA dental composite before and after leaching in organic solvents
Authors: Anne Rathbun M. , Craig Robert G. , Hanks Carl T. , Filisko Frank E. 
Published: December 2004

AbstractCell culture techniques were used to determine the source of cytotoxic agents in a commercial BIS‐GMA composite. The material was polymerized according to the manufacturer′s directions and leachable components were removed by room temperature extraction in ethanol, chloroform, or toluene. The leachable components in the extracts were identified using infrared spectrographic analysis. Thin layer chromatographic analysis was used to determine the number of constituents. These constituents were separated by gas chromatography and then identified by mass spectrographic analysis. Succinic dehydrogenase activity and radioactive labeling with tritiated leucine were used to evaluate cell metabolism and protein synthesis, respectively. The infrared analysis of the extracts showed that the primary component was unreacted BIS‐GMA. Trace amounts of 2‐hydroxy‐4‐methoxy‐benzophenone, a light stabilizer, as well as a phenyl ester of benzoic acid which was probably degraded from BIS‐GMA, were detected by the mass spectrographic method. The removal of leachable components caused a 90% decrease in toxicity compared to the nonextracted BIS‐GMA samples. The extracted BIS‐GMA samples showed no cellular response compared to the Teflon negative control.
The periapical tissue reactions to a calcium phosphate cement in the teeth of monkeys
Authors: Hong Y. C. , Wang J. T. , Hong C. Y. , Brown W. E. , Chow L. C. 
Published: December 2004

AbstractA calcium phosphate cement, Grossman sealer, and Sargenti N2 were compared under conditions where root canals of monkey incisors were deliberately overfilled and the apical tissue responses were evaluated histologically. The periapical tissues exposed to Sargenti N2 revealed severe irritation at all times through the 6‐month experimental period. The reactions to Grossman sealer were milder but persisted throughout the observation period. The calcium‐phosphate‐cement treated animals showed mild tissue irritation after 1 month, but thereafter the adverse tissue reactions were minimal. New bone formation adjacent to the cement was also observed. These results point to the possibility that calcium phosphate cement might be used in simplified endodontic procedures. The compatibility of calcium phosphate cement with the periapical tissue suggests that the cement may have other applications in dentistry and medicine.
Quantitative analysis of in vivo tissue responses to titanium‐oxide‐ and hydroxyapatite‐coated titanium alloy
Authors: Hayashi K. , Uenoyama K. , Matsuguchi N. , Sugioka Y. 
Published: December 2004

AbstractWe have previously studied a large number of histological specimens of biomaterials and found that regions with and without an intervening fibrous membrane coexisted in many specimens. Therefore, it appears necessary to perform an evaluation of the entire specimen when histologically assessing the affinity of bone for a biomaterial. Accordingly, we performed a quantitative histological evaluation of hydroxyapatite (HAP)‐ and titanium‐ oxide(TiO2)‐coated Ti‐6Al‐4V and uncoated Ti‐6Al‐4V (control) by determining the affinity index. This was defined as the length of bone directly opposed to the implant/the total length of the bone‐‐implant interface X 100%. The test materials were inserted into the distal epiphyseal region of the femurs of adult dogs, and follow‐up quantitative histological comparisons were performed from 4 weeks to 96 weeks. The HAP‐coated implants had the highest affinity index 4 weeks after insertion, and this superiority was maintained up to 96 weeks. There was a significant difference in affinity index between HAP‐coated implants and control implants (P < 0.001), while TiO2‐coated implants showed no significant difference in comparison to the control.
The role of an endothelial cell lining in limiting distal anastomotic intimal hyperplasia of 4‐mm‐I.D. Dacron grafts in a canine model
Authors: Graham Linda M. , Brothers Thomas E. , Vincent Christopher K. , Burkel William E. , Stanley James C. 
Published: December 2004

AbstractThe effect of an endothelial cell (EC) lining on intimal hyperplasia at the distal anastomosis of Dacron grafts was assessed in a canine model. Enzymatically derived autologous EC were used to seed 14 to 17 cm long, 4 mm I.D., knitted Dacron aortoiliac grafts implanted in an end‐to‐side manner in six dogs (Group I). Unseeded grafts were similarly implanted in six control dogs (Group II). All animals received acetylsalicylic acid (325 mg po qd) 24 h prior to graft placement and for 2 weeks postoperatively. Distal anastomotic intimal hyperplasia (AIH) and luminal surface EC coverage were quantitated at the conclusion of a 16‐week study period. Patency for Group I and Group II grafts were 90% and 55%, respectively (p = 0.07). Maximum AIH, defined as the maximum reduction of luminal cross‐sectional area at the distal anastomosis, was not significantly different between Group I (13.1 ± 8.0%) and Group II (15.1 ± 7.3%) conduits. However, AIH was inversely related to the extent of luminal EC coverage (r = −0.6, p < 0.05), thus greater endothelialization was associated with decreased AIH. These data support the idea that EC coverage of the luminal surface of prosthetic vascular grafts may limit the development of AIH.
Postadsorptive transitions in fibrinogen adsorbed to Biomer: Changes in baboon platelet adhesion, antibody binding, and sodium dodecyl sulfate elutability
Authors: Chinn Joseph A. , Posso Sylvia E. , Horbett Thomas A. , Ratner Buddy D. 
Published: December 2004

AbstractResidence‐time‐dependent changes in fibrinogen after its adsorption to Biomer were examined by measuring platelet adhesion and antibody binding to the adsorbed protein, and the amount of adsorbed fibrinogen which could be eluted by sodium dodecyl sulfate (SDS). Baboon fibrinogen was first adsorbed (from either pure solution or dilute plasma) to Biomer, which was then stored in either buffer or buffered albumin solution prior to testing. Subsequently, the adherent protein layer was either probed for fibrinogen capable of mediating platelet adhesion using 111In radiolabeled, washed platelet suspensions under both static and shearing conditions, or for fibrinogen capable of binding antibody using a direct enzyme linked immunosorbent assay (ELISA). Alternatively, the surface with the adsorbed protein layer was soaked in a 3% SDS solution, and the amount of 125I radiolabeled fibrinogen retained was measured. Decreases in platelet and antibody binding, and in the SDS elutability of the adsorbed fibrinogen after it was stored in buffer were detected, although different rates of decrease were observed for each method. When the protein‐coated surfaces were stored in buffered albumin solution rather than buffer, the decrease in the reactivity of fibrinogen was prevented. While each of the three assays measures a different property of adsorbed fibrinogen, this study suggests that the adherent protein undergoes time dependent conformational changes which render it less reactive toward platelets and antibodies, and more resistant to elution by SDS.
Negative cilia concept for thromboresistance: Synergistic effect of PEO and sulfonate groups grafted onto polyurethanes
Authors: Han Dong Keun , Jeong Seo Young , Kim Young Ha , Min Byoung Goo , Cho Han Ik 
Published: December 2004

AbstractIn order to investigate the interaction between various sulfonated polyurethanes (PUs) and blood, a commercial PU surface was chemically modified by poly(ethylene oxide) (PEO), dodecanediol(DDO), and propane sultone to give hydrophilic, hydrophobic, and negative sulfonated surfaces, respectively. The blood compatibility of modified PUs was evaluated by an in vitro platelet adhesion test, activated partial thromboplastin time (APTT), and prothrombin time (PT) measurements as well as an ex vivo rabbit A‐A shunt method. In the platelet adhesion test, the hydrophilic PEO grafted PUs showed less platelet adhesion than untreated PU and hydrophobic DDO grafted PU. Sulfonated PU‐PEO exhibited a lower degree of adhesion and shape change of platelet. The APTT and PT, especially APTT, of the sulfonated PUs were extended, whereas those of PU‐PEO and PU‐DDO did not show any significant change compared with untreated PU. Meanwhile, in the ex vivo experiment, hydrophilic PEO grafted PUs showed longer occlusion times than untreated PU or hydrophobic DDO grafted PU. In addition, the incorporation of SO3 groups at the end of PU‐DDO and PU‐PEO, particularly PU‐PEO‐SO3, exhibited an enormous prolongation in occlusion time, indicating a synergistic effect of the hydrophilic PEO and the negative SO3 groups on thromboresistance. These occlusion times corresponded well to in vitro evaluation results: the less adhesion and shape change of platelet and the longer APTT and PT, the more extended the ex vivo occlusion time.
Preparation of thermo‐responsive membranes. II
Authors: Nozawa Iwao , Suzuki Yosuke , Sato Shuji , Sugibayashi Kenji , Morimoto Yasunori 
Published: December 2004

AbstractTwo types of liquid crystal (LC)‐immobilized membranes were prepared by a soaking method and sandwich method to control the permeation of indomethacin, as a model drug, in response to local and systemic fever. Monooxyethylene trimethylolpropane tristearate (MTTS) was used as a model LC because it has a gel‐liquid crystal phase transition temperature near the body temperature, 39–40°C in phosphate buffered saline (pH 7.4). Two porous polypropylene (PP) membranes were soaked into 20% MTTS chloroform solution in the soaking method, and two PP membranes were poured with the melted MTTS and pressed in the sandwich method. Thermo‐response efficacy of the soaked membrane was dependent upon the content of MTTS in MTTS membrane, and the MTTS content above the void volume of PP membrane (38%) was needed for high efficacy. On the other hand, the sandwich membrane exhibited higher thermo‐response efficacy than the soaked membrane, because more LC was embedded in the pores of sandwich membrane than that of the soaked membrane. The sandwich membrane permeation of indomethacin was sharply controlled by temperature changes between 32 and 38°C.
Macrophage activation induced by different carbon fiber‐epoxy resin composites
Authors: Peluso G. , Ambrosio L. , Cinquegrani M. , Nicolais L. , Tajana G. 
Published: December 2004

AbstractThe activation of cells by interaction with solid surfaces is important in many settings, including the response of tissue to implanted materials. However, few comprehensive studies of both cell migration and activation have been performed so that the connection between these events and immunological activation against foreign material is not well understood. In the present study, synthesis and expression of Ia antigens by peritoneal exudate macrophages after implantation of different carbon fiber composites in the rat peritoneal cavity have been investigated in order to determine whether the type of material implanted affected the composition of Ia‐bearing cells of the exudate. The results have confirmed the low level of expression of Ia on resident peritoneal macrophages; while we have found that macrophages, harvested after implantation, express a different amount of Ia related to the different cure cycles of the composite materials used.
Effect of some additives on the biostability of a poly(etherurethane) elastomer
Authors: Wu Y. , Zhao Q. , Anderson J. M. , Hiltner A. , Lodoen G. A. , Payet C. R. 
Published: December 2004

AbstractFour materials based on a single poly(etherurethane) (PEU) prepared from MDI and PTMEG but differing in additives were studied in the cage implant systm. The two additives studied were Santowhite powder at the 1% level and Methacrol 2138F 5%. Methacrol 2138F appeared to be immiscible with the base PEU and was dispersed in discrete domains about 0.5‐μm in size. The retrieved PEU specimens were also cleaned and examined in the optical and scanning electron microscopes, and the size and density of adherent foreign body giant cells (FBGCs) were measured at implantation times up to 10 weeks. Methacrol 2138F had no effect on the density, coverage or size distribution of adherent FBGCs, but leaching of Methacrol 2138F was considered to be responsible for extensive pitting of the PEU surface. On the other hand, Santowhite powder appeared to inhibit formation of FBGCs, and while surface cracking and flaking were observed as early as 3 weeks postimplantation on some PEUs, the Santowhite powder effectively inhibited surface cracking and flaking up to the longest implantation time studied.
Polymorphonuclear leukocyte degranulation with exposure to polymethylmethacrylate nanoparticles
Authors: Papatheofanis Frank J. , Barmada Riad 
Published: December 2004

AbstractPolymethylmethacrylate (PMMA) is clinically employed in a wide range of orthopaedic procedures. The etiology of the inflammatory reaction of recipient tissues to PMMA remains unresolved. Classically, polymorphonuclear leukocytes (PMNs) release cytoplasmic lysosomal granules when exposed to a variety of proinflammatory stimuli. Such degranulation contributes, and partially defines, the local tissue reaction to this foreign material. In the present investigation, PMMA particles (50–60 nm) were mixed with human PMNs, and the amount of lactate dehydrogenase, lysozyme, and β‐glucuronidase released from the cells was quantitated. In all cases, a dosedependent increase in degranulation followed the addition of increasing amounts of PMMA to the PMNs. In addition, the migration of PMNs was diminished in a dose‐dependent manner with exposure to increasing amounts of the cement. These results suggested that PMMA stimulates the release of leukocyte lysosomal contents and alters the migration characteristics of these cells in a manner that is consistent with the local inflammatory reaction to this cement.
Low wear rate of UHMWPE against zirconia ceramic (Y‐PSZ) in comparison to alumina ceramic and SUS 316L alloy
Authors: Kumar Praveen , Oka Masanori , Ikeuchi Ken , Shimizu Koichiro , Yamamuro Takao , Okumura Hideo , Kotoura Yoshihiko 
Published: December 2004

AbstractPartially stabilized zirconia ceramic is being recognized among ceramics for its high strength and toughness. With this ceramic, is possible to manufacture a 22‐mm‐size femoral head for low friction arthroplasty of the hip joint in association with an ultra‐high‐molecular‐weight polyethylene socket. Wear‐resistant properties of zirconia ceramic were screened on two principally different wear devices. Sterile calf bovine serum, physiological saline, and distilled water were chosen as the lubricant fluid media. Depending on the lubricant medium, the wear factor of polyethylene against zirconia ceramic counterfaces was 40 to 60% less than that against alumina ceramic counterfaces, and 5 to 10 times lower than with the SUS316L metal counterfaces. Polyethylene wear against metal was more susceptible in saline in which it had 2 to 3 times higher wear rate than with serum. On the other hand, different fluid media had little effect on polyethylene wear against ceramic counterfaces. In each set of tests, the wear factor obtained on an unidirectional wear device showed 10 to 15 times higher values, in comparison to the wear factor estimated on a reciprocating wear device.
An in vivo model to study the pathobiology of infectious biofilms on biomaterial surfaces
Authors: Buret A. , Ward K. H. , Olson M. E. , Costerton J. W. 
Published: December 2004

AbstractThis study examines the morphology, ultrastructure, and microbiology of the intact biofilm developing on an implant surface. Silastic subdermal implant material was colonized with P. aeruginosa and surgically inserted into the peritoneal cavity of adult rabbits. After 4, 8, 28, and 42 days implants were recovered and the intact biofilms examined. P. aeruginosa colonized the implant throughout the entire experimental time. Microcolonies of glycocalyx‐coated bacteria were observed within the biofilm. However, the bulk of the biofilm was host‐generated and typically contained phagocytes trapped within a thick mesh of fibrin. Polymorphonuclear neutrophils were the predominant cell type. Isolated erythrocytes, macrophages, and fibroblasts were also observed. By day 28, the biofilm was enclosed in a fibrous capsule of vascularized connective tissue. The low numbers of neutrophils seen in biofilms from sterile Silastic sheets implanted into control animals suggested that neutrophilia may represent a specific cellular response to the bacterial colonization. The results indicate that the cell‐mediated immune response provides for most of the biofilm mass on colonized implant surfaces. Inactivated phagocytes trapped in fibrin may “wall‐off” the embedded bacterial micro‐colonies and thus shield them from live phagocytic leucocytes. Such a mechanism may play an important role in the pathogenesis of prosthetic device infections.
Platelet consumption by polyvinyl alcohol coated tubing in canines
Authors: Ip W. F. , Sefton M. V. 
Published: December 2004

AbstractPolyvinyl alcohol (PVA)‐coated polyethylene tubing, with or without immobilized heparin, caused severe thrombocytopenia and enhanced the production of new platelets when inserted in a chronic arteriovenous shunt in canines. A similar length of uncoated polyethylene tubing neither lead to thrombocytopenia nor significantly enhanced platelet regeneration, relative to the shunt only without a test section. Platelet regeneration was monitored by the malondialdehyde assay, which was assumed to make a distinction between “new” and “old” platelets. This distinction was combined with the platelet count values to enable calculation of the cumulative consumption curve and the initial fractional consumption rate in the presence of a non constant platelet count. The resulting initial fractional consumption rates were: 34%/day for PVA, 20.5%/day for polyethylene, and 18%/day for the shunt only blank.
Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs
Authors: Buser D. , Schenk R. K. , Steinemann S. , Fiorellini J. P. , Fox C. H. , Stich H. 
Published: December 2004

AbstractThe purpose of the present study was to evaluate the influence of different surface characteristics on bone integration of titanium implants. Hollow‐cylinder implants with six different surfaces were placed in the metaphyses of the tibia and femur in six miniature pigs. After 3 and 6 weeks, the implants with surrounding bone were removed and analyzed in undecalcified transverse sections. The histologic examination revealed direct bone‐implant contact for all implants. However, the morphometric analyses demonstrated significant differences in the percentage of bone‐implant contact, when measured in cancellous bone. Electropolished as well as the sandblasted and acid pickled (medium grit; HF/HNO3) implant surfaces had the lowest percentage of bone contact with mean values ranging between 20 and 25%. Sandblasted implants with a large grit and titanium plasmasprayed implants demonstrated 30–40% mean bone contact. The highest extent of bone‐implant interface was observed in sandblasted and acid attacked surfaces (large grit; HCl/H2SO4) with mean values of 50–60%, and hydroxylapatite (HA)‐coated implants with 60–70%. However, the HA coating consistently revealed signs of resorption. It can be concluded that the extent of bone‐implant interface is positively correlated with an increasing roughness of the implant surface.
Prevention of bacterial colonization on polyurethane in vitro by incorporated antibacterial agent
Authors: Golomb Gershon , Shpigelman Arie 
Published: December 2004

AbstractThe presence of implanted biomaterials increases host susceptibility to infections. Once established, biomaterial‐mediated infections are resistant to treatment and persist until the device is removed. The objective of this work was to study the prevention of bacterial‐biofilm formation on polymeric implant (polyurethane) by controlled release of incorporated antibacterial agents (parabens). By embedding parabens in PU by the solvent‐cast method, matrices with amorphous dispersions (or solid solutions) were obtained. Release rate modulation was achieved by using different MW parabens and by a rate‐limiting membrane. Preliminary in vitro antibacterial studies of both methyl and propyl paraben matrices exhibited significant inhibition of Staphylococcus epidermidis biofilm formation. Propyl paraben matrices (15 and 20% w/w drug load) decreased the number of colony‐forming units on PU surface to 2 × 104/mL, in comparison to 6 × 105 on control polymers. This significant reduction was obtained without any effect on the number of viable bacteria in the suspension culture. This type of delivery system provides regional prophylactiv activity by creating a high local concentration of antibacterial agent.
Calcium phosphate formation at the surface of bioactive glass in vitro
Authors: Andersson Ö. H. , Kangasniemi I. 
Published: December 2004

AbstractThe calcium phosphate formation at the surface of bioactive glass was studied in vitro. Glass rods and grains were immersed in different aqueous solutions and studied by means of scanning electron microscopy and energy dispersive x‐ray analysis. Surface morphological changes and weight loss of corroded grains were monitored. In‐depth compositional profiles were determined for rods immersed in the different solutions. The solutions used were tris‐buffer (trishydroxy‐methylaminomethane + HCl), tris‐buffer prepared using citric acid (trishydroxy‐methylaminomethane + C6H8O7·H2O), and a simulated body fluid, SBF, containing inorganic ions close in concentration to those in human blood plasma. It was found that the calcium phosphate formation at the surface of bioactive glass in vitro proceeds in two stages. When immersing the glass in tris or in SBF a Ca,P‐rich surface layer forms. This accumulation takes place within the silica structure. Later, apatite crystals forming spherulites appear on the surface. The Ca/P‐ratio of initially formed calcium phosphate was found to be about unity. It is proposed that this is due to bonding of phosphate to a silica gel. The surface is stabilized, i.e., leaching is retarded, by the rapid Ca,P‐accumulation within the silica structure before apatite crystals are observed on the surface. It is proposed that the initially formed calcium phosphate is amorphous and that the crystallization is initiated within the silica gel. The crystallizing surface provides nucleation sites for extensive apatite formation on the glass surface. In the presence of citrate no Ca,P‐accumulation occur at the glass surface, but soluble Ca‐citrate complexes form. By comparing the weight loss during corrosion in tris with that in the calcium and phosphate containing SBF, it is possible to establish whether the glass can induce apatite formation at its surface or not.