bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collagen at interfaces I. In situ collagen adsorption at solution/air and solution/polymer interfaces
Authors: Deyme Michel , Baszkin Adam , Proust Jacques Emile , Perez Eric , Boissonnade Marie Martine 
Published: December 2004

AbstractCollagen was isolated from rat tail tendons and acetylated with 1–14C acetic anhydride. In situ adsorption of this collagen from a buffer solution (pH = 2.7) was measured at the interfaces to air, polyethylene and polyethylene grafted with poly(maleic acid), respectively.The kinetics of adsorption were recorded for all surfaces studied and the corresponding diffusion coefficients for collagen in solution with various protein concentrations were calculated. The desorption of collagen from polymer surfaces was also studied.These experiments reveal the existence of both a reversibly and an irreversibly adsorbed collagen layer on the polymers tested. The desorption/adsorption ratio for the polyethylene is higher than that for the grafted polyethylene indicating stronger interactions of collagen with the grafted surface than with the non‐modified polyethylene.
Polymer coating for hemoperfusion over activated charcoal
Authors: Hasirci N. , Akovali G. 
Published: December 2004

AbstractPlasma polymerization (glow discharge) was used to make a polymeric coat with hexamethyldisiloxane on the surface of activated charcoal granules. These samples were examined with ESCA and SEM for surface chemical analysis, coat thickness, and uniformity, and for changes in surface topography. The effects of the coat on absorptive capacity and release of fine particles were examined.
Suppression of platelet activity on microdomain surfaces of 2‐hydroxyethyl methacrylate‐polyether block copolymers
Authors: Okano Teruo , Uruno Michio , Sugiyama Norihide , Shimada Masashi , Shinohara Isao , Kataoka Kazunori , Sakurai Yasuhisa 
Published: December 2004

AbstractBlock copolymers constructed from chains of poly(2‐hydroxyethyl methacrylate) (PHEMA) and either poly‐ethyleneoxide (PEO) or poly‐propyleneoxide (PPO) were synthesized. These block copolymers exhibited microdomain structure. Platelet adhesion on their surfaces was investigated by a column elution method to examine the effect of microdomain structure. The number of platelets adhered from whole blood was smaller for the block copolymer systems than for the homopolymers. Minimum points of platelet adhesion appeared at approximately 0.38 mol fraction of HEMA in the HEMA‐PO system. Both block copolymer surfaces showed microdomains of alternate lamellar structure. Furthermore, the percent of platelets released from the column after incubation was investigated using PRP. In the case of homopolymers, released platelet percentages decreased with an increase of incubation time. Released platelet percentages from the block copolymers, however, were nearly constant with changing incubation time. These results showed that HEMA‐EO and HEMA‐PO block copolymers had the ability to suppress both reversible and irreversible adhesion of platelets to their respective microdomain surfaces.
Influence of mixing technique on some properties of PMMA bone cement
Authors: Eyerer P. , Jin R. 
Published: December 2004

AbstractPMMA bone cements (Refobacin‐Palacos R, Sulfix 6, AKZ, and CMW bone cement, types I and II), from six different clinics, were investigated in three stages. In the first stage, studies of density, hardness, flexural strength, and compressive strength were made, as well as molecular weight measurements and microscopic investigations. These studies reflected the current state of techniques of application used in operating theaters. They revealed wide variations in the properties of the materials studied.Secondly, a comprehensive study of the process‐technology in the laboratory was performed. The following variables were investigated or discussed: mixing vessel, order of the individual components, mixing time, rate of mixing, pressure application on the mixed bone cement, kneading, cement thickness, pouring into the syringe, contact force during polymerization, and preparation quantity.The third stage involved the development and clinical testing of an improved mixing technique. Using this improved mixing technique, all three selected clinics achieved far better results with reduced variability. A comparison between a centrifuging technique after mixing and our improved, but conventional, mixing technique, displays advantages for the latter.The question regarding a correlation between cement specimens of high porosity and early implant loosening could not be answered on the basis of the 43 PMMA bone cement explants investigated (implanted 6 months to 15 years).In some cases, the studies revealed that the bone cement manufactureres should be required to revise and quantify existing instructions for use. The users, on the other hand, should give more consideration to the mixing technique and its consequences.
Bonding strength of alkyl‐2‐cyanoacrylates to bone in vitro
Authors: Kilpikari J. , Lapinsuo M. , Törmälä P. , Pätiälä H. , Rokkanen P. 
Published: December 2004

AbstractThis study measured the bonding strength between alkyl‐2‐cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6–11.2 N/mm2). In long‐term experiments under water, n‐ and i‐butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long‐term strength.
Short‐term biocompatibility studies of hydrogel‐grafted collagen copolymers
Authors: Amudeswari S. , Nagarajan B. , Reddy C. Rami , Joseph K. Thomas 
Published: December 2004

AbstractSynthetic hydrogels are an interesting class of biomaterials. Hydrogels were prepared by the graft copolymerization of either HEMA and MMA or HEMA and GDMA onto soluble collagen using different cross linking agents. The tissue compatibility of these hydrogels was studied by implantation in rats. It was observed that there were no untoward rejection phenomena of these gels when implanted in vivo except for the typical healing process. The hydrogels were well tolerated and might well serve as good tissue equivalents.
In vitro testing of dental materials by means of macrophage cultures I: Methodological aspects
Authors: Syrjänen Stina , Nilner Krister , Hensten‐Pettersen Arne 
Published: December 2004

AbstractMacrophages play a central role in the pathogenesis of inflammation. In addition, activated macrophages are the first cells to come in contact with foreign particles in tissue. In the present study the applicability of macrophages for In vitro biological screeining of dental materials was tested. Monolayers of murine peritoneal macrophages were prepared. After three days culture the macrophages were inoculated with alloy particles prepared from silver and tin (Ag3Sn), the γ‐phase of dental silver‐amalgam. After different inoculation periods the macrophages were fixed and examined with phase contrast microscopy, scanning electron microscopy, and energy dispersive x‐ray analysis. Comparison with phagocytosis of particles injected intraperitoneally was also performed. Macrophage cultures inoculated with Latex particles served as controls. Ten minutes after inoculation with alloy particles, about 58% of the macrophages had ingested particles. EDAX‐analysis indicated that the phagocytized alloy particles contained both silver and tin in the same proportions as in the original alloy. When the cultures had been inoculated for ten days, however, a marked reduction in phagocytosis was observed probably due to cytolysis of those macrophages which initially had phagocytized the alloy particles. The results indicate that, although the Ag3Sn alloy particles at all the time intervals studied were phagocytized more slowly and to a lesser extent than the Latex particles, the method could be of value in studying the biocompatibility of dental materials available in particulate form.
The biological performance of calcium phosphate ceramics in an infected implantation site III: Biological performance of β‐whitlockite in the noninfected and infected rat middle ear
Authors: Van Blitterswijk C. A. , Grote J. J. , Koerten H. K. , Kuijpers W. 
Published: December 2004

AbstractThe biological performance of macroporous β‐whitlockite implanted in the rat middle ear was evaluated. The material was studied in the non‐infected middle ear and in middle ears infected by Staphylococcus aureus. β‐whitlockite was quickly covered by a normal mucosa. One week post‐operatively the macropores were filled with exudate, fibrous tissue, and a small quantity of bone. Six months after the operation the greater part of the macropore area was filled with bone (74%); fibrous tissue accounted for 20%, and exudate for 5%. In histological sections, the macropore area of β‐whitlockite had increased by 68% after six months, indicating biodegradation. Macrophages and multinucleated cells were present in the vicinity of the implant and played a role in this biodegradation. Besides cytoplasmic vacuoles containing calcium phosphate, the cells showed smaller granules containing trace elements originally present in the implant material, such as silicon, titanium, aluminum, iron, and magnesium.
The effect of HIPing on the fatigue and tensile strength of a cast, porous‐coated CoCrMo alloy
Authors: Georgette F. S. , Davidson J. A. 
Published: December 2004

AbstractThe process required to sinter porous CoCrMo alloys results in the formation of substrate porosity through carbide dissolution. Since hot isostatic pressing (HIPing) has been shown to eliminate casting porosity in the CoCrMo alloy, it is possible that it may be equally effective on pores that are generated from the sintering operation. The effect that HIPing a porous‐coated CoCrMo material has on the fatigue and tensile properties was investigated. Fatigue testing was performed on sintered materials as well as sintered and HIPed materials, both with and without a porous coating. Further, the effect of varying coating thickness on the resulting fatigue strength of sintered and HIPed materials was studied. Light microscopy was performed in order to define the microstructural changes brought about by the various thermal cycles. Scanning electron microscopy was utilized to define the crack initiation process. The fatigue strength of uncoated “as sintered” materials was found to be reduced by 34% relative to the “as cast” condition. The same material that was HIPed revealed a fatigue strength slightly lower than the “as cast” condition. It was found that porous coatings created preferential sites for fatigue crack initiation. However, the presence of the coating did not further reduce the fatigue strength of “as sintered” materials because of the already low strength created by the sintering operation. Materials that were sintered exhibited a lowering in both tensile strength and elongation to failure relative to the “as cast” condition. The HIPing of sintered materials improved both fatigue and tensile properties relative to the “as sintered” condition.
Histopathologic evaluation following chronic implantation of chromium and steel based metal alloys in the rabbit central nervous system
Authors: Rauch Helene C. , Ekstrom Merlin E. , Montgomery Ilene N. , Parada Frank , Berke Joseph 
Published: December 2004

AbstractHistopathologic evaluation of three metal alloys for chronic implanatation in the central nervous system (CNS) was undertaken in rabbits. Throughout the 8 month evaluation period the inflammatory response to the alloys was bland. Two of the alloys tested (chromium based MP35N, Trademark of the Standard Pressed Steel Company, and a stainless steel alloy, BG42 VacArc, Trademark of Latrobe Steel) appeared suitable as CNS implants. The third alloy (stainless steel 440C, Carpenter Steel Company) showed more corrosion than the other alloys, and may be less suitable for implantation. While E. cuniculi infection was found in four rabbits, the infection did not directly interfere with the assessment of the histologic changes directly due to the implants. Autoantibodies to a brain constituent were not observed.
Bone bonding behavior of three kinds of apatite containing glass ceramics
Authors: Kitsugi Toshiaki , Yamamuro Takao , Nakamura Takashi , Higashi Shoichiro , Kakutani Yoshiaki , Hyakuna Katsufumi , Ito Setsuro , Kokubo Tadashi , Takagi Masataka , Shibuya Takehiro 
Published: December 2004

AbstractWe have produced three kinds of apatite‐containing glass ceramics of the same chemical composition: MgO (4.6), CaO (44.9), SiO2 (34.2), P2O5 (16.3), CaF2 (0.5) (in weight ratio). They contain different crystal combinations and have different mechanical properties.The first glass ceramic (A–;GC) was prepared by heating a glass plate to 870°C. It contains only oxy‐ and fluoroapatite (35 wt%). The second glass ceramic (A–W–GC), and the third (A–W–CP–GC), were prepared by heating glass powder compacts to 1050°C and 1200°C, respectively. A–W–GC contains oxyapatite and fluoroapatite (Ca10(PO4)6(O,F2)) (35 wt%) and β‐wollastonite (40 wt%). A–W–CP–GC contains oxyapatite and fluoroapatite (20 wt%), β‐wollastonite (CaO·SiO2) (55 wt%), and β‐whitlockite (3CaO·P2O5) (15 wt%). The bending strengths of A–;GC, A–W–GC, and A–W–CP–GC were 88MPa, 178MPa, and 213MPa, respectively, in air.Rectangular ceramic plates (15mm × 10mm × 2mm) were implanted into a rabbit tibia. Ten and 25 weeks after implantation, the segment of tibia with implant was excised for examination. The segment was held by a special jig and the traction breaking load (failure load) was measured by an autograph.A–;GC showed a lower load than A–W–GC and A–W–CP–GC. The loads for A–W–GC and A–W–CP–GC were almost equal. The failure loads did not change significantly between 10 and 25 weeks for any of the materials.The interface was examined by Giemsa surface staining, contact micro‐radiography, and SEM‐EPMA. Giemsa surface staining and CMR revealed direct bonding between the materials and the bone for all the three materials.SEM‐EPMA showed that Si and Mg content decreased, Ca content did not change, and P content increased at the reaction zone between all three glass ceramics and bone. This was observed at 10 weeks, as well as at 25 weeks, after implantation. The reaction zone was narrowest with A–;GC, wider with A–W–GC, and widest with A–W–CP–GC.
A histologic and mechanical evaluation of carbon‐coated polyester suture
Authors: Cook Stephen D. , Kester Marcus A. , Brunet Michael E. , French H. Graeme , Haddad Ray J. , Haubold Axel D. 
Published: December 2004

AbstractUltra low temperature isotropic (ULTI) carbon‐coated polyester suture material was evaluated histologically and mechanically in dogs. These results were compared to those obtainedfor uncoated polyester and polybutylate coated polyester. The suture materials were used in therepair of the surgically incised medical collateral ligament and subcutaneous tissues to evaluate the potential of the carbon‐coated system for ligamentous repairs. Following surgery, the dogs were sacrificed at periods of 1–48 weeks postoperatively for evaluation of tissue biocompatibility and mechanical strength of the materials. The polybutylate‐coated polyester suture broke at lower force levels than did comparable sizes of uncoated or carbon‐coated polyester. All three types showed a high retention (>98%) of mechanical strength at 48weeks, often exhibiting an increase in tensile strength due to tissue ingrowth. The histologic response to carbon‐coated polyester was equal to or better than the response to either the uncoated polyester or polybutylate‐coated polyester. A greater degree of tissue growth into the carbon‐coated material was evident at most time periods following an initial acute inflammatory response which was also present in the other materials.
Evaluation of the in vitro and ex vivo blood compatibility of primary reference materials
Authors: Pelzer H. , Heimburger N. 
Published: December 2004

AbstractThe blood compatibility of the primary reference materials, low density polyethylene and polydimethylsiloxane, was evaluated using human in vitro and human ex vivo test devices, and was compared with that of polyetherurethane and polyvinylchloride. The effect of the materials on in vitro platelet activation was studied by measurement of platelet factor 4 release by enzyme immunoassay. The adsorption of fibrinogen and platelets from human native blood onto the surface of the material was measured using enzyme immunoassay technique. The four materials tested exhibited significantly different effects on in vitro platelet activation. In addition, the materials adsorbed fibrinogen and platelets to a different extent under ex vivo test conditions. Materials, which induced strong in vitro platelet activation, e.g. low density polyethylene and polyvinylchloride, demonstrated high concentrations of fibrinogen and platelets on the surface when tested under ex vivo conditions. Polydimethylsiloxane and polyetherurethane, which induced slight in vitro platelet factor 4 release, adsorbed significantly lower concentrations of fibrinogen and platelets from human native blood.
Growth of bone marrow cells on porous ceramics in vitro
Authors: Uchida Atsumasa , Nade Sydney , McCartney Eric , Ching William 
Published: December 2004

AbstractFollowing the transplantation of bone marrow cells to extra‐osseous sites, bone formation occurs in those sites. This osteogenic potential of bone marrow cells might be utilized for filling defects in bone if they could be transported on porous ceramic materials. Before such an approach becomes feasible, it is important to know what happens to the cells in the presence of the ceramics that might be used. In order to investigate the interaction between bone marrow cells and ceramics, in vitro, a system for culturing bone marrow cells on ceramic materials has been developed. Bone marrow cells adhered well to the surface of calcium hydroxyapatite and tricalcium phosphate ceramics, and this was followed by the formation of fibrous tissue on and within the ceramics. These ceramics were compatible with bone marrow cells even in culture conditions in which there was a large surface area of ceramic interfacing with cells. The results support the proposal that calcium hydroxyapatite and tricalcium phosphate are appropriate as bone replacement materials. In contrast, calcium aluminate had an adverse effect on bone marrow cells when there was a high proportion of ceramic to culture medium. However, this effect was not present if the proportion of ceramic to culture medium was low. Therefore, a large amount of biodegradable porous calcium aluminate ceramic should not be used as an alternative to autogeneous bone grafting.
Composites for use in posterior teeth: Composition and conversion
Authors: Ruyter Ivar Eystein , Øysæd Harry 
Published: December 2004

AbstractThe purpose of this investigation was to determine the composition, as well as the conversion after polymerization, of some dental composite materials. Eight posterior composites and two anterior composites were investigated. The weight and volume fractions of inorganic fillers were determined by combustion and pycnometric analyses. The monomers were analyzed qualitatively and quantitatively by high performance liquid chromatography, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Infrared multiple internal reflection spectroscopy was applied for determination of conversion of the methacrylate groups. The conversion in light activated materials was examined at shallow depths, that is, the level of optimal conversion. This investigation demonstrated that the conversion can be correlated with the composition of monomers and oligomers used in the materials.
Specific removal of paraquat by hemoperfusion through antiparaquat conjugated agarose‐polyacrolein microsphere beads
Authors: Azhari Rosa , Margel Shlomo , Labes Ari , Haviv Yolanta 
Published: December 2004

AbstractA novel specific adsorbent for removal of paraquat from blood has been developed. Immobilized antiparaquat antibodies provide the specificity and high affinity of the adsorbent. The antibodies were raised in rabbits and goats immunized with an analogue of paraquat, conjugated to bovine serum albumin (BSA). Specific antiparaquat antibodies were isolated from the animals' sera by affinity chromatography. The antibodies were polyvalently bound to crosslinked agarose‐polyacrolein microsphere beads (APAMB). Antiparaquat conjugated beads (APB) were used as packing material in a hemoperfusion column for detoxification of paraquat and were compared to activated charcoal. In vitro and in vivo experiments showed specific and enhanced rate of removal of paraquat from plasma and blood by using APB. Minimal alteration of the formed elements and plasma constituents of the blood was observed.
Tissue biocompatibility of kevlar aramid fibers and polymethylmethacrylate, composites in rabbits
Authors: Henderson James D. , Mullarky Richard H. , Ryan Doreen E. 
Published: December 2004

AbstractTwo groups of female NZW rabbits were implanted in the paravertebral muscles with aramid (du Pont Kevlar aramid 49) fibers and aramid‐polymethylmethacrylate (PMMA) composites for 14 and 28 days. Rabbits were killed at these times periods, necropsies performed, sites scored for gross tissue response, and tissue specimens containing the implants removed for histopathological evaluation. A mild fibrous tissue reaction was observed around all implants containing aramid fiber similar to that observed around the silicone control implant. Some foreign body giant cells were also present adjacent to the fibers. An intense necrotic inflammatory reaction was present around the positive control material (PVC Y‐78). The tissue response to implantation of aramid fiber and fiber‐PMMA composites indicates that aramid is a biocompatible material.
125I‐fibrinogen uptake on peripheral venous cannulas: A comparison between different cannula materials and coatings
Authors: Lindblad Bengt , Johansson Arne 
Published: December 2004

AbstractUsing a similar technique as 125I‐Fibrinogen uptake test for detection of deep venous thrombi, the radioactivity over cannulas inserted into veins on the dorsal aspect of the hands was measured 1, 2, 4 and 24 h after insertion. In three groups of 10 postoperative patients it was by random allocation inserted on one side a siliconized tetrafluorethylene cannula and on the other side one of either: a nonsiliconized tetrafluorethylene, a heparinized tetrafluorethylene or a fluorethylenpropylene cannula. The same volume and type of infusion was given in both cannulas. No difference in protein deposition was seen between siliconized and nonsiliconized tetrafluorethylene. A tendency of lower protein deposition, especially at 24 h on heparinized tetrafluorethylene was found. The fluorethylenpropylene cannulas had both over cannula and adjacent vein higher protein deposition at all measurements compared to the siliconized tetrafluorethylene cannula (p < 0.01). The results implicate that fluorethylenprophylene could induce a higher incidence of thrombophlebitis than tetrafluorethylene cannulas.