bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and antithrombogenicity of polyetherurethaneurea containing quaternary ammonium groups in the side chains and of the polymer/heparin complex
Authors: Ito Yoshihiro , Sisido Masahiko , Imanishi Yukio 
Published: December 2004

AbstractNovel polyetherurethaneureas containing tertiary amino groups in the side chains (PAEUU) were synthesized, quaternized with different alkyl halides (Q‐PAEUU), and heparinized (H‐PAEUU). The antithrombogenicity of PAEUU in vitro was improved by quaternization, and further by heparinization. The excellent antithrombogenicity of H‐PAEUU was controlled by the kind of quaternizing agent through the polar effect of quaternizing agent on the water content and through the steric effect of quaternizing agent on the heparin content of H‐PAEUU. The antithrombogenicity of H‐PAEUU was found to be affected by the water content more strongly than by the heparin content. H‐PAEUUs containing tertiary amino groups in the main chain, which were synthesized previously, showed a little better shortterm antithrombogenicity than the present H‐PAEUUs containing tertiary amino groups in the side chains. Since ammonium groups in the side chains of Q‐PAEUU impose little steric hindrance against the heparin adsorption, the release of heparin from the side chains of H‐PAEUU was slower but lasted longer than that from the main chain. Therefore, the present H‐PAEUU is expected to be a longterm antithrombogenic material.
In vitro testing of dental materials by means of macrophage cultures: II. Effects of particulate dental amalgams and their constituent phases on cultured macrophages
Authors: Syrjänen S. , Hensten‐Pettersen A. , Nilner K. 
Published: December 2004

AbstractIt is known that macrophages play an important role in the removal of foreign particulate matter from tissue. When powdered dental amalgam is introduced into the soft tissues an amalgam tattoo is formed due to the intracellular degradation of amalgam by macrophages and their polykaryons. It was therefore feasible to study the effects of particulate amalgams as well as their individual phases on macrophages in vitro. The parameters compared were rate of the phagocytosis, changes of cellular morphology, and release of lactate dehydrogenase (LDH) to demonstrate plasma membrane permeability. It was shown that all the alloys except the Sn8Hg particles (γ2‐phase) and γ2‐containing Revalloy were effectively phagocytized by macrophages, and the alterationsin cellular morphology were slight during the first day. Prominant cellular damage was seen in cultures treated with particulate Ag2Hg3 (γ1‐phase) and Revalloy for 1 week. A slight increase in LDH activity in the medium was seen one hour after the alloy treatment. The LDH activities due to the amalgam treatment increased in the order Dispersalloy < Revalloy < Sybraloy. Intraperitoneal phagocytosis did not cause any morphological changes in macrophages, but the per cent of phagocytosis was diminished.
Synthesis and antithrombogenicity of anionic polyurethanes and heparin‐bound polyurethanes
Authors: Ito Yoshihiro , Sisido Masahiko , Imanishi Yukio 
Published: December 2004

AbstractTwo kinds of novel antithrombogenic polyurethane materials were synthesized. One of them is a polyetherurethane with anionic charges on the film surface, and the other is a polyetherurethaneurea to which heparin was covalently bound. The mechanism of their antithrombogenicity was investigated. The anionic polyetherurethane selectively adsorbed albumin, did not cause a conformational change of plasma proteins adsorbed, and suppressed the adherence and deformation of platelets but did not deactivate the blood–clotting system, thus leading to a moderate antithrombogenicity. The heparin‐bound polyetherurethaneurea was not favorable for the selective adsorption of albumin, caused the denaturation of plasma proteins adsorbed, and induced the adherence and deformation of platelets but deactivated the blood‐clotting system, leading to excellent antithrombogenicity. For the investigation of blood‐material interaction, the importance of a multiparameter estimation of the activation of platelets and the blood‐clotting system was indicated.
Adsorption of plasma proteins to the derivatives of polyaminoetherurethaneurea: The effect of hydrogen‐bonding property of the material surface
Authors: Sanada Takashi , Ito Yoshihiro , Sisido Masahiko , Imanishi Yukio 
Published: December 2004

AbstractPolyaminoetherurethaneureas bearing tertiary amino groups in the main chain (M‐PAEUU) were synthesized, quaternized (Q‐M‐PAEUU) and heparinized (H‐M‐PAEUU). With increasing portions of diisocyanate and with decreasing portions of polyaminoether in the feed, M‐PAEUU containing more hydrogen‐bonded urea carbonyl groups was prepared. With increasing hydrogen‐bonding character of M‐PAEUU, the adsorbed bovine serum albumin (BSA) was more denatured. By quaternization of M‐PAEUU, the protein adsorption increased, but the denaturation of adsorbed proteins was suppressed. With increasing ratio of hydrogen‐bonded urea carbonyl groups in Q‐M‐PAEUU, the adsorptions of BSA, bovine serum γ‐globulin (BγG), and bovine plasma fibrinogen (BPF) were decreased, but the degree of denaturation of adsorbed proteins was increased. In the adsorption to H‐M‐PAEUU, both the amount and the degree of denaturation of adsorbed proteins were strongly decreased. The dynamic adsorption experiments of plasma proteins showed the behaviors which are similar to the equilibrium adsorption experiments. The decrease of hydrogen‐bonded urea linkages and the increase of hydrophilicity by quaternization and heparinization of the polymer surface may be favorable for building up a hydration layer on the surface, thus suppressing the denaturation of plasma proteins which may trigger blood clotting and thrombus formation.
Elongation of brachymetatarsy with ceramic implant: A roentgenographic evaluation of its utility
Authors: Takaoka Kazuo Yonenobu Kunio , Tsuyuguchi Yuichi , Ono Keiro , Tada Koichi 
Published: December 2004

AbstractThe metatarsal bone was elongated by intercalary implantation of a single‐crystal alumina ceramic in 7 patients with brachymetatarsy. The implants were encased with new bone 24 months after surgery and resulted in 5.2 to 9.2 mm elongation of the metatarsal bone. The response of the bone to the ceramic implant was observed roentgenographically. No resorption or pseudoarthrosis of the bones, nor loosening or breakage of the implants, were observed. The alumina ceramic implant proved to be a useful substitute for a bone graft, because of its biocompatibility and strength.
Threaded versus porous‐surfaced designs for implant stabilization in bone‐endodontic implant model
Authors: Maniatopoulos C. , Pilliar R. M. , Smith D. C. 
Published: December 2004

AbstractAn endodontic implant model system was used to compare the effect of implant design on stabilization in bone. Specifically a porous‐surfaced design was compared to conventional threaded and smoothtapered endodontic implant designs. All implants were placed in immediate function thereby assessing the effect of early limited movement on the fixation achieved. A total of eighty‐three endodontic implants were inserted in the mandibles of six adult mongrel dogs. Animals were sacrificed immediately after implantation and after 3, 6, and 12 months. Implants were evaluated by clinical and radiographic examination and after animal sacrifice by pull‐out tests of the implant from the tissues, SEM examination of the pulled‐out implants and, finally, histology. The pull‐out test results indicated increasing shear strength with implantation time for the porous‐surfaced implants in contrast to the gradual loss of fixation for the threaded implants and the continuous low shear strength for the smooth implants. Histological studies and SEM examination indicated the reason for these changes. Smooth implants became encapsulated by fibrous connective tissue from early post‐implantation time periods. Threaded implants, although initially mechanically interlocked with bone, developed a fibrous connective tissue capsule that gradually thickened with time until, by 6 months, little mechanical interlock of bone and implant was present. It was assumed that this fibrous capsule thickening was caused by implant movement. The porous‐surfaced implants, however, became stabilized by bone ingrowth and showed more extensive bone formation within the surface pores with time. It is concluded that for implants that are made functional immediately after implantation, as in this study, porous‐surfaced implants can become strongly fixed by bone ingrowth, in contrast to conventional threaded or smooth‐surfaced designs, thus presenting a more favourable long term prognosis.
Measurements of thermal properties for human femora
Authors: Biyikli Suleyman , Modest Michael F. , Tarr Richard 
Published: December 2004

AbstractIn this study, density, specific heat, thermal conductivity, and thermal diffusivity were measured experimentally along the lengths of human cadaveric femora. Fresh and dry bone samples were selected from both male and female specimens, and for different age groups varying between44 and 73 years old. Measured values for specific heat vary between 1.14 and 2.37 J/gm°C; forthermal conductivities the range is from 0.16 to 0.34 W/m°C; and for thermal diffusivities the range is from 0.10 to 0.23 cm2/sec, depending on whether the bone samples were freshor dry, cancellous or cortical. The experimental results are presented in non‐dimensional coordinates and are compared with the few other data available in the literature.
Macrophage activation with multi‐porous beads prepared from partially deacetylated chitin
Authors: Nishimura Keiko , Nishimura Shin‐Ichiro , Seo Hiroshi , Nishi Norio , Tokura Seiichi , Azuma Ichiro 
Published: December 2004

AbstractThe effect of multi‐porous beads prepared from 80% deacetylated chitin on the activation of mouse peritoneal macrophages was examined. Deacetylated chitin bead (DAC‐bead) preparations were shown to activate macrophages for tumoricidal activity depending on the increasing concentration of acetic acid used for the pretreatment of beads. The large DAC‐bead was more susceptible to treatment with acetic acid than small DAC‐bead, and showed more potent capacity for the activation of macrophages under the same pretreatment conditions with acetic acid. Reacetylated bead preparations, on the other hand, showed less activities. In addition, DAC‐bead pretreated with acetic acid stimulated macrophages to produce interleukin 1. The possibilities of multi‐porous beads as cancer chemotherapeutic‐carrier were examined by the method of column chromatography and of in vitro antitumor experiment. Forty‐four percent of adriamycin adsorbed on the surface of and in bead was released within the first 60 min. of elution, and then adriamycin was released more slowly in proportion to the elution time. Antitumor activity of adriamycin‐adsorbed bead was less effective than that of free adriamycin if they were compared on the basis of total content of adriamycin.
Molecular weight distribution of a bulk ultra‐high molecular weight polyethylene product—impax 5M+ UHMW–NAT
Authors: Kusy R. P. , Whitley J. Q. 
Published: December 2004

AbstractA bulk ultra‐high molecular weight polyethylene product, IMPAX 5M+ UHMW–NAT, was fractionated using an increasing‐temperature sequential‐extraction technique. In the presence of an inert atmosphere and an antioxidant, 5 g of material were methodically dissolved in decahydronaphthalene over the temperature range, 80–191°C. Initially, intrinsic viscosities were measure in decalin at 135°C by single point capillary viscometry. From this data the viscosity average molecular weights were estimated using a logarithmic expression. Results showed that the intrinsic viscosities (molecular weights) increased linearly with extraction temperature over a range from 10 to 40 dL/g (1 to 8 × 106) and that the molecular weight distribution was log normal. Mass balances both before and after extraction indicated that less than 0.3% of the material had a molecular weight less than 106 and that less than 0.1% of the material was gel. Zero shear viscometry of bulk fractionated polymer and powdered whole polymers confirmed that capillary viscometry increasingly under‐estimates the true intrinsic viscosities as the polymer chain lengths (molecular shear forces) increase. Indeed, the actual molecular weights ranged from about 2–14 × 106. Knowledge of the molecular weight distribution of bulk products and the presence of either volatiles or crosslinked networks is critical for the continued design and development of superior wearing and fatigueresistant implants.
Textile arterial prostheses: Is water permeability equivalent to porosity?
Authors: Guidoin Robert , King Martin , Marceau Daniel , Cardou Alain , De La Faye Dominique , Legendre Jean‐Michel , Blais Pierre 
Published: December 2004

AbstractPorosity and water permeability are two distinct terms that describe different characteristics of vascular prostheses. The porosity is a measure of the void fraction within the prosthesis wall and is believed to give a rough prediction of the capacity of the graft to anchor newly formed surrounding tissue after implantation, whereas the water permeability indicates the rate at which water can flow through the prosthesis wall and, when measured under physiological pressure conditions, provides the surgeon with information about the need for preclotting prior to implantation. The literature has not always clearly distinguished between these two terms, and some authors in fact have suggested that they both refer to the same property of a prosthesis. In an attempt to clarify the issue, porosity and water permeability measurements were made on 34 commercial vascular prostheses having different textile constructions. Linear regression analysis demonstrated that these two characteristics are only weakly related (r = 0.59). It is therefore recommended that the current draft standards for such devices reference both properties: porosity and water permeability.
A calorimetric study of the interaction of synthetic phospholipid liposomes with lipid‐soluble small molecules used as dental materials and devices
Authors: Fujisawa Seiichiro , Kadoma Yoshinori , Masuhara Eiichi 
Published: December 2004

AbstractThe interaction of 22 lipid‐soluble small molecules, widely used in dental materials and devices, with synthetic phospholipid liposomes, was investigated by the application of differential scanning calorimetry (DSC), in order to clarify the mechanism of small molecules in biological systems. Dimyristoyl phosphatidyl choline (DMPC) and dipalmitoyl phosphatidyl choline (DPPC) were used as lipids. The interaction of various monomers with liposomes has been reported by us in this journal.1 In this experiment, various compounds such as redox‐initiator, photo‐initiator or photo‐sensitizer, inhibitor, root‐canal disinfectant, cement‐base materials (eugenol and 2‐ethoxybenzoic acid) etc., were investigated. From changes in the phase transition temperature (T), enthalpy (ΔHkcal mol−1) and H/HHW values of both DMPC and DPPC liposomes induced by these molecules, it was concluded that aromatic tertiary amine, benzoyl peroxide and hydroquinone monomethyl ether had a relatively large effect on liposomes, and that in phenol derivatives, m‐cresol and p‐chlorophenol had a large effect on liposomes compared to phenol. Eugenol used as dental cement also had a large effect on liposomes due to its high hydrophobicity. Changes in the transition properties of liposomes induced by small molecules (characterized by shift of T to a lower temperature, an increase or decrease in cooperativity (H/HHW), and a decrease in ΔH of a endothermic peak) seemed to be related to biological activities.
A kinetic study on the effects of anticoagulants on the interaction of fibrinogen and thrombin
Authors: Nakanishi Eiji , Sato Hiroko , Nakajima Akio 
Published: December 2004

AbstractThe inhibitory effect of heparin and antithrombin III (AT) on the interaction of fibrinogen and thrombin was investigated in preference to studies on heparinizing devices. The turbidity was measured kinetically as a measure of the concentration of fibrin polymer formed in the system. It was found that AT did not act on fibrinogen but, rather, on thrombin, and the main role of heparin is to accelerate the AT‐thrombin reaction. On the other hand, dextran sulfate (DSc) did not accelerate the AT‐thrombin reaction. When heparin and AT were incubated with thrombin, inhibition did not depend on the mixing order but on the incubation time. Thus, a ternary complex of heparin, AT, and thrombin was supposed to form for the inhibition. The reaction of heparin with fibrinogen and thrombin in the presence of AT was well‐explained by assuming a Freundlich‐type adsorption of heparin analogous with the reaction of heparin with fibrinogen.
Polarimetric assay for the determination of the native collagen content of soluble collagen
Authors: Nagelschmidt Manfred , Viell Burckhard 
Published: December 2004

AbstractTwo standardized assays for determining the amount of native collagen in a collagen solution are described which are based on polarimetric measurements. Native collagen content is calculated from the loss of optical rotation during transition from the original to the denatured conformation using constants which were obtained from standard collagen of highest available native collagen content. While Method I gives information on the content of helical collagen, Method II estimates collagen which is resistant to peptic degradation. Both methods are simple to perform and suitable for routine quality control.
Biodegradation of a polyurethane in vitro
Authors: Phua S. K. , Castillo E. , Anderson J. M. , Hiltner A. 
Published: December 2004

AbstractThis study examines the effect of in vitro exposure to enzymes on the performance properties of Biomer®, a segmented polyetherurethane used in a number of blood‐contacting devices such as catheters, heart assist pumps, and chambers for artificial hearts. The ultrathin samples were treated with two proteolytic enzymes, papain and urease, for periods of 1–6 months at 37°C. The treated Biomer® samples were subjected to chemical and physical analysis. Effects of biodegradation by the enzymes were assessed by fatigue tests, gel permeation chromatography (GPC), and attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) analysis. Papain was found to be more effective in degrading the polymer than urease. Mechanisms for enzymic degradation are proposed.
Quantitative bone remodelling resulting from the use of porous dental implants
Authors: Keller J. C. , Young F. A. , Natiella J. R. 
Published: December 2004

AbstractHistomorphometric analyses were used to quantitatively determine the patterns of bony ingrowth which resulted from the placement of porous‐surfaced dental implants into the mandibles of Rhesus monkeys for up to 74 months utilizing a two‐stage approach. Quantitative histopathologic evaluations were made using ground section microscopy. Implant stability resulting from bone remodelling and ingrowth occurred to varying degrees with all implants. Bone ingrowth occurred from medullary trabeculae and contact with the adjacent cortical plates. Quantitative histomorphometric analyses revealed that in only one case was the bone ingrowth into the available internal pores less than 45%. Minimal fibrous connective tissue ingrowth was observed in the implant crypts and was not thought to be due to micromotion. The observed bone remodelling indicated a favorable prognosis for long‐term implant performance.
Collagen at interfaces II: Competitive adsorption of collagen against albumin and fibrinogen
Authors: Deyme Michel , Baszkin Adam , Proust Jacques Emile , Perez Eric , Albrecht Geneviève , Boissonnade Marie Martine 
Published: December 2004

AbstractAdsorption of chemically radiolabeled [14C] collagen from binary mixtures with albumin or fibrinogen was studied on the solution/air and solution/polyethylene interfaces and revealed the preferential adsorption of albumin. This phenomenon is confirmed by the data of surface tension measurements of single protein, collagen‐albumin, and collagen‐fibrinogen solutions. Desorption experiments clearly show that more irreversibly adsorbed collagen was found on polyethylene surfaces when adsorption was performed from collagen‐fibrinogen than from collagen‐albumin solutions. The combined adsorption‐desorption and the surface tension data show that competitive adsorption of collagen at the hydrophobic surfaces is strongly influenced by the surface tension properties of the proteins in solution.
Water sorption of polymethacrylate networks: Bis‐GMA/TEGDM copolymers
Authors: Kalachandra S. , Turner D. T. 
Published: December 2004

AbstractPolymethacrylate networks were made by copolymerization of a range of compositions of bis‐GMA and triethylene glycoldimethacrylate (TEGDM). Polymerization was initiated both by heating with benzoyl peroxide or by photopolymerization (λ > 400 nm) using camphoroquinone as sensitizer. The uptake of water increased from 3 to 6% as the proportion of TEGDM increased from 0 to 1.0. Intermediate compositions took up less water than would be predicted from the law of mixtures. Volumetric changes were determined and clinical significance discussed. A copolymer prepared by photopolymerization took up more water as the temperature was increased from 24–60°C. In this range, values of the diffusion coefficient (D) conformed to the Arrhenius equation, D = D0 exp (−E/RT), giving E = 42–46 kJ/mol and D0 = 0.13 cm2 s−1.
Ion implantation of surgical Ti‐6Al‐4V for improved resistance to wear‐accelerated corrosion
Authors: Buchanan R. A. , Rigney E. D. , Williams J. M. 
Published: December 2004

AbstractThe influence of nitrogen‐ion implantation on the wear‐accelerated corrosion behavior of surgical Ti‐6Al‐4V was studied. Non‐passivated and prepassivated unimplanted Ti‐6Al‐4V specimens were employed as controls for comparison. Corrosion rates as a function of time at open‐circuit corrosion potentials were electrochemically measured in saline and serum solutions under both static and wear conditions. The wear parameters simulated those of a total artificial hip under average walking conditions. The results indicated that prepassivation of the control material was beneficial under static‐corrosion conditions, but not under wear‐corrosion conditions. The nitrogen‐ion implantation process was found to significantly improve the material's resistance to wear‐acceler‐ated corrosion in both saline and serum solutions.
Vascular graft‐associated complement activation and leukocyte adhesion in an artificial circulation
Authors: Kottke‐Marchant Kandice , Anderson James M. , Miller Kathleen M. , Marchant Roger E. , Lazarus Hillard 
Published: December 2004

AbstractComplement‐associated leukocyte adhesion appears to be a consistent in vitro and in vivo finding for many types of polymers; however, very little work has been done on the interaction of leukocytes with vascular graft materials. An in vitro perfusion system was used to study complement and leukocyte activation associated with the following vascular graft materials when tested with human blood: expanded polytetrafluoroethylene (ePTFE), crimped Dacron Bionit (DB) and preclotted Dacron Bionit. A decrease in the total leukocyte concentration with perfusion time was seen for all materials tested, and paralleled leukocyte adhesion to the graft surface as observed by scanning electron microscopy. The most dramatic decrease in leukocyte concentration was observed for the interaction of heparinized whole blood with Dacron. This was due to a selective decrease in neutrophils and monocytes, and was correlated with an increase in both leukocyte adhesiveness and complement activation, as measured by C5a elevation. Inhibiting complement activation by use of the anticoagulant, sodium citrate, curtailed Dacron‐induced leukocyte adhesion. Little leukocyte or complement activation was observed for ePTFE or the silicone rubber control regardless of the anticoagulant used.