bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluoroapatite glass‐ceramic coating on alumina: Surface behavior with biological fluids
Authors: Bosetti M. , Vernè E. , Brovarone C. Vitale , Moisescu C. , Sabbatini M. , Cannas M. 
Published: August 2003

AbstractThe results of a surface analysis performed on a fluoroapatite‐based glass ceramic (SAF) also coating a full‐density α‐alumina substrate (SAF‐alumina coating) are presented. These two materials have also been evaluated after soaking in simulated body fluid to understand their ability to induce hydroxyapatite growth on them. Aiming to understand the fluoroapatite glass‐ceramic interaction with some plasma proteins, in the second part of this study, fibronectin, albumin, immunoglobulin G, IgA, and complement factor C3c SAF binding have been evaluated; surface activity on complement activation has also been quantified. SAF‐alumina coating provides good sites for the nucleation and growth of an apatite layer, equivalent to the mineral component of bone and binds preferentially plasma fibronectin, which is well known to enhance cell adhesion and spreading. Moreover, SAF‐alumina coating reduces alumina complement activation directly or via reduced IgA binding. Alumina was shown to bind the same C3 fragments as Zymosan, used as complement activating control, and to induce increased levels of serum soluble iC3b and Bb. A mechanical resistant material with enhanced bioactivity, bone integration, and reduced inflammatory potential respect to alumina has been obtained. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 615–621, 2003
Inhibitor of complement, Compstatin, prevents polymer‐mediated Mac‐1 up‐regulation of human neutrophils independent of biomaterial type tested
Authors: Schmidt S. , Haase G. , Csomor E. , Lütticken R. , Peltroche‐Llacsahuanga H. 
Published: August 2003

AbstractThe inflammatory reaction after cell contact with polymer materials is primarily mediated by activated neutrophils and may, in some cases, lead to exhaustion of neutrophil cell function. A direct consequence of this can be impairment of local or even systemic host defense mechanisms, which in turn can result in foreign body infections. Neutrophil activation, as indicated by the up‐regulation of the Mac‐1 adhesion receptor, is a reliable parameter for estimating the inflammatory risk due to implanted biomaterials. Because at blood contact, biomaterials immediately acquire a material‐specific layer of blood proteins on their surface, including fibrinogen, complement, and immunoglobulin G, it is generally believed that after biomaterial contact, neutrophil activation primarily occurs by interaction with this protein layer. In this study, using our recently established polymer bead in vitro assay, we investigated whether complement inhibition alone can reduce biomaterial‐mediated neutrophil activation, independent of the type of polymer and, hence, also its surface chemistry. Complement inhibition was achieved by using Compstatin, a recently developed complement inhibitor that binds to the complement component C3 preventing C3 convertase formation. We revealed significantly reduced (p ≤ 0.025) Mac‐1 receptor expression levels after 45 min of blood contact with the following polymers (without and with Compstatin): 1. polyurethane, 98.3%, 13.6%; 2. polymethylmetacrylate, 88.5%, 11.0%; and poly‐D,L‐lactide, 71.8%, 8.4%. Although these three polymer types acquire material‐specific protein layers because of their different surface chemistry, complement inhibition by Compstatin alone proved to be sufficient to reduce neutrophil activation after surface contact, thus reducing the risk of biomaterial‐mediated inflammatory reaction. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 491–499, 2003
Synthesis and characterization of a novel polymer–ceramic system for biodegradable composite applications
Authors: Yang Liu , Wang Jian , Hong Jason , Santerre J. Paul , Pilliar Robert M. 
Published: August 2003

AbstractThe objective of this study was to develop a biodegradable polymer resin that could be used for the fabrication of an interpenetrating phase composite (IPC) made of porous calcium polyphosphate (CPP) and an organic polymer resin. The resin was synthesized from a polycarbonate‐based divinyl oligomer and monomers containing ionic groups. The physical and chemical properties of the polymer resin and polycarbonate‐based divinyl oligomer were characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, and swelling studies. The in vitro degradation of the polymer resins was assessed using cholesterol esterase in a buffer solution at 37°C for 3 weeks. Scanning electron microscopy of the degraded samples indicated that the hydrolysis of the resin was catalyzed by the enzyme. The relative interfacial shear strength between the polymer resin and the CPP ceramic was studied using a microbond test. The addition of ionic groups into the polymer resin chains appeared to improve the chemical bonding between the polymer and the CPP. Preliminary mechanical properties of the IPC were investigated by determining bending strength using a three point bending test. The data showed a sevenfold increase in strength over that of the monolithic CPP, and the addition of more ionic groups into the resin led to a higher bending strength for the newly formed CPP/polycarbonate resin system. Sample cross sections of the IPC examined using scanning electron microscopy suggested that the resin had infiltrated almost all of the pores of the CPP. The results of this study indicate that the IPC could potentially be used for fabricating novel biodegradable load‐bearing implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 622–632, 2003
Model porous surfaces for systematic studies of material‐cell interactions
Authors: Petronis Sarunas , Gretzer Christina , Kasemo Bengt , Gold Julie 
Published: August 2003

AbstractA model system for studying cell‐surface interactions, based on microfabricated cell culture substrates, has been developed and is described here. Porous surfaces consisting of interconnecting channels with openings of subcellular dimensions are generated on flat, single crystal, silicon substrates. Channel size (width, depth), distribution, and surface coating can be varied independently and used for systematic investigation of how topographical, chemical, and elastic surface properties influence cell or tissue biological responses. Model porous surfaces have been produced by using two different microfabrication methods. Submicron‐sized channels with very high depth‐to‐width aspect ratios (up to 30) have been made by using electron beam lithography and anisotropic reactive ion etching into single‐crystal silicon. Another method uses thick‐resist photolithography, which can be used to produce channels wider than 1 μm and with depth‐to‐width aspect ratios below 20 in an epoxy polymer. Preliminary cell culture tests show that fibroblasts bridge 0.8‐ to 1.8‐μm‐wide channels with very few exceptions (i.e., a continuous space below the cell‐surface interface is created). It has also been shown that variation of channel periodicity significantly affects fibroblast morphology and attachment density. With this model system, it is possible to load the channels with bioactive substances intended to interact with cells at or near the surface in a time‐dependent manner. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 707–721, 2003
Deposition of complement protein C3b on mixed self‐assembled monolayers carrying surface hydroxyl and methyl groups studied by surface plasmon resonance
Authors: Hirata Isao , Hioki Yasunori , Toda Mitsuaki , Kitazawa Takayuki , Murakami Yoshinobu , Kitano Etsuko , Kitamura Hajime , Ikada Yoshito , Iwata Hiroo 
Published: August 2003

AbstractSince complement activation is recognized as a common response of the host defense system when an artificial medical device is applied to a patient, great effort has been devoted to studies on the interaction of the complement system with artificial materials. However, some uncertainties remain, partially because of the lack of well characterized surfaces and suitable analytic methods for study of the surface phenomena that occur on artificial materials under physiologic conditions. In this study, we employed self‐assembled monolayers (SAMs) and the surface plasmon resonance (SPR) technique to study interactions of the serum complement with well characterized surfaces. Self‐assembled monolayers carrying various concentrations of hydroxyl groups were prepared using 11‐mercapto‐1‐undecanol (C11‐OH) and one of n‐nonanethiol, n‐dodecanethiol, and n‐hexadecanethiol. The amount of NHS deposition on the SAMs increased with increasing C11‐OH content of the SAMs, and the amount of anti‐C3b antibody immobilization formed on the NHS deposition layers increased with increasing C11‐OH content of the SAMs. These results clearly demonstrate that a large amount of C3b, produced through the activation of the complement system, binds covalently to and is adsorbed by hydroxyl‐group‐rich surfaces. The combination of SAMs and the SPR technique is suitable for studying the interaction of the complement system with solid surfaces, and the results should give basic information needed for a rational design of biocompatible surfaces on synthetic materials. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 669–676, 2003
Spatially organized layers of cardiomyocytes on biodegradable polyurethane films for myocardial repair
Authors: McDevitt Todd C. , Woodhouse Kimberly A. , Hauschka Stephen D. , Murry Charles E. , Stayton Patrick S. 
Published: August 2003

AbstractTissue engineering constructs should match the physical and mechanical properties of the native tissue. This implies that pliable scaffolds might be better suited for soft‐tissue applications than rigid polymeric materials. In this study, we examined spatially organized cardiomyocyte cultures on biodegradable, elastomeric polyurethane films patterned by microcontact printing of laminin lanes. The resulting cardiomyocyte patterns on polyurethane displayed a similar morphology to those previously achieved for up to 7–10 days on other substrates, such as polystyrene dishes. However, the integrity of the cardiomyocyte patterns on thin, spin‐cast or solvent‐cast polyurethane films was retained for up to 4 weeks in culture. When additional cardiomyocytes (labeled with Cell Tracker reagents) were seeded onto the patterned cultures, secondary and tertiary cell populations aligned between and on top of the primary patterned cells to form a multilayered, organized tissue construct approximately 2–3 cell layers thick. In addition, dense, highly aligned monolayers of patterned cardiomyocytes were able to contract the thin, solvent‐cast polyurethane films. These results indicate that elastomeric, biodegradable polyurethane films can serve as an appropriate scaffold material to support stably the engineering of spatially organized layers of cardiomyocytes in vitro. This approach may serve as a novel method for transplantation of organized cardiac tissue constructs to the heart for myocardial repair. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 586–595, 2003
In vitro biocompatibility assessment of sulfonated polyrotaxane‐immobilized polyurethane surfaces
Authors: Park Hyung Dal , Lee Won Kyu , Ooya Tooru , Park Ki Dong , Kim Young Ha , Yui Nobuhiko 
Published: August 2003

AbstractSulfonated polyrotaxanes (PRx‐SO3's), in which sulfonated α‐cyclodextrins (α‐CDs) were threaded onto the poly(ethylene glycol) (PEG) segments in a PEG‐b‐poly(propylene glycol) (PPG)‐b‐PEG triblock copolymer (Pluronic) capped with benzyloxycarbonyl (Z)‐L‐phenylalanine (Z‐L‐Phe), were prepared as a novel surface‐modifying biomaterial. Surface modification of the polyurethane (PU) was carried out by blending the PRx‐SO3's with a PU solution, followed by solution casting. The incorporated PRx‐SO3's led to the enhanced hydrophilicity by changing the surface properties of the PU matrix. Modified PUs showed the stable entrapment of the PRx‐SO3's with little extraction into water and enhanced mechanical properties after exposure to water compared to the PU control. The incorporated PRx‐SO3's repelled the proteins and kept them from closely approaching the surface areas, prevented platelet activation by thrombin, and effectively repelled bacteria. These results suggest that both the supramolecular structure of the polyrotaxanes and exposure of the sulfonated groups onto the surfaces contribute to these phenomena. Thus, surface modification with PRx‐SO3's is suggested to be useful for the fabrication of biocompatible medical devices. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 596–604, 2003
Human neutrophil elastase inhibition with a novel cotton‐alginate wound dressing formulation
Authors: Edwards J. Vincent , Bopp Alvin F. , Batiste Sarah L. , Goynes Wilton R. 
Published: August 2003

AbstractOcclusion and elasticity were combined in a novel cotton‐based alginate dressing containing a nontoxic elastase inhibitor. Cotton gauzes were modified with a textile finishing process for incorporating alginate to yield a dressing material that retains elasticity while enhancing absorption. The algino‐cellulose conjugates were formed through citric acid crosslinking of cellulose and alginate. The alginate‐citrate finishes were applied to cotton gauzes in various formulations containing citric acid, sodium hypophosphite, and polyethylene glycol. The modified gauzes contain a citrate conjugate of alginate and cellulose that gels upon hydration. The alginate‐citrate finishes were combined with the neutrophil elastase inhibitor, oleic acid, to demonstrate the ability of the algino‐cellulose fibers to release the inhibitor and neutralize destructively high levels of neutrophil elastase found in nonhealing and burn wounds. Four types of gauzes were examined for the effect of the algino‐cellulose finish on cotton gauze absorbency and elasticity. Fourier transform infrared (FTIR) spectroscopy of the film and alginate‐citrate finished cotton showed formation of the alginate and citrate cellulose esters. Scanning electron microscopy analysis revealed large areas of the yarn surface covered by the alginate film with a smooth surface on the original fibers. Wetting of the gauze surface resulted in formation of a hydrated gel on the yarns with apparent swelling of the film and the fiber‐coated alginate. Published 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 433–440, 2003
Bioactive glasses as accelerators of apatite bioactivity
Authors: Vallet‐Regí M. , Rámila A. , Padilla S. , Muñoz B. 
Published: August 2003

AbstractSynthetic carbonatehydroxyapatite is the ceramic closest to the mineral component of human bone and seems, therefore, the optimum material to use in osseous implants. However,in vitroassays performed to determine its bioactivity have shown no positive results after 2 months of assay. With the aim of improving this bioactivity, a new biphasic material was synthesized composed mainly of synthetic carbonatehydroxyapatite and only 5% of a sol‐gel bioactive glass.In vitroassays were assessed to determine the bioactive behavior of this new material and revealed that the addition of a minimal amount of bioactive glass is enough to induce bioactivity on synthetic carbonatehydroxyapatites. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 580–585, 2003
Polyvinylalcohol three‐dimensional matrices for improved long‐term dynamic culture of hepatocytes
Authors: Saavedra Yascara Grisel Luna , Mateescu Mircea A. , Averill‐Bates Diana A. , Denizeau Francine 
Published: August 2003

AbstractRat hepatocytes were seeded on three‐dimensional highly porous polyvinylalcohol (PVA) and aminoethyl‐modified polyvinylalcohol (AE‐PVA) matrices. Hepatocytes were cultured under static and dynamic conditions. The three‐dimensional matrices offered an improved extracellular microenvironment for long‐term (5 days) maintenance of hepatocytes, compared to reference monolayer cultures on collagen. Cellular adhesion exceeded 80% with a viability superior to 70%. The preservation of albumin secretion after 5 days of culture was two times higher for static cultures on three‐dimensional matrices (18% on PVA, 13% on AE‐PVA) and three times higher for dynamic three‐dimensional cultures (25% PVA and AE‐PVA), compared to the static two‐dimensional culture on collagen film (8%). The biotransformation of ammonia into urea was also maintained throughout the culture period. The addition of the aminoethyl function demonstrated no toxicity for the hepatocyte cultures. This function could be suitable eventually to further improve the hepatocyte culture system by linking more specific adhesion molecules on the polymer surface. This study demonstrated the efficiency of polyvinylalcohol as a three‐dimensional matrix coupled to a perfusion culture system, which improves extracellular conditions for hepatocyte survival and promotes preservation of long‐term hepatospecific functions. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 562–570, 2003
Effect of strain and strain rate on fatigue‐accelerated biodegradation of polyurethane
Authors: Wiggins Michael J. , Anderson James M. , Hiltner Anne 
Published: August 2003

AbstractA diaphragm‐type film specimen was used to study in vitro degradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading. This geometry allowed both uniaxial and biaxial loading in a single experiment. During testing, the film was exposed to a H2O2/CoCl2 solution that simulated in vivo oxidation of PEUU. The combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation. The effects of biaxial strain magnitude and strain rate were examined separately by increasing the frequency of fatigue loading from 0 to 1 Hz with constant maximum biaxial strain and by changing the maximum biaxial strain while maintaining constant strain rate. In the ranges of biaxial strain energy (0.17 to 0.55 MPa) and strain rate (0 to 46% s−1) tested, the rate of degradation increased with increasing strain rate whereas strain magnitude had essentially no effect on degradation rate. Although loading conditions affected the rate of oxidative degradation, ATR‐FTIR analysis suggested that in all cases the mechanism of degradation did not change. Chemical degradation produced a brittle crosslinked surface layer marked by dimpling and pitting, as observed with scanning electron microscopy. Pits served as stress concentrators and initiated environmental stress cracks under dynamic loading but not under static (creep) loading. Small pits were sufficient to initiate cracks at higher strain rates whereas only large pits initiated cracks at lower strain rates. Consequently, a higher strain rate produced more profuse cracking. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 463–475, 2003
Repositioning of cells by mechanotaxis on surfaces with micropatterned Young's modulus
Authors: Gray Darren S. , Tien Joe , Chen Christopher S. 
Published: August 2003

AbstractAdherent cells are strongly influenced by the mechanical aspects of biomaterials, but little is known about the cellular effects of spatial variations in these properties. This work describes a novel method to produce polymeric cell culture surfaces containing micrometer‐scale regions of variable stiffness. Substrates made of acrylamide or poly(dimethylsiloxane) were patterned with 100‐ or 10‐μm resolution, respectively. Cells were cultured on fibronectin‐coated acrylamide having Young's moduli of 34 kPa and 1.8 kPa, or fibronectin‐coated PDMS having moduli of 2.5 MPa and 12 kPa. Over several days, NIH/3T3 cells and bovine pulmonary arterial endothelial cells accumulated preferentially on stiffer regions of substrates. The migration, not proliferation, of cells in response to mechanical patterning (mechanotaxis) was responsible for the accumulation of cells on stiffer regions. Differential remodeling of extracellular matrix protein on stiff versus compliant regions was observed by immunofluorescence staining, and may have been responsible for the observed mechanotaxis. These results suggest that mechanically patterned substrates might provide a general means to study mechanotaxis, and a new approach to patterning cells. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 605–614, 2003
Resorption patterns of calcium‐phosphate cements in bone
Authors: Gisep A. , Wieling R. , Bohner M. , Matter S. , Schneider E. , Rahn B. 
Published: August 2003

AbstractTwo calcium phosphate cements, one monophasic and the other biphasic, have been used as bone void filler in a sheep model. The cements were injected into a slot defect in the proximal tibia and into a cylindrical defect in the distal femur. In this study, we focused on the resorption pattern of the two cement formulations and the subsequent biologic reaction. Bone remodeling occurred synchronously with the resorption of the implant material in a creeping substitution process. Cracks and pores in the monophasic cement were filled with osseous tissues. The biphasic cement showed faster resorption of the matrix. The more slowly resorbing granules were surrounded by newly grown bone, thus providing an inverse scaffold for cancellous bone regeneration. In highly loaded areas, the long‐term support function of the fixation appears to be critical. Because cortical bridging of the defects was seen in only one case, it can be concluded that calcium‐phosphate cements are preferentially suitable as cancellous bone substitute materials. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 532–540, 2003
TEGDMA‐induced toxicity in human fibroblasts is associated with early and drastic glutathione depletion with subsequent production of oxygen reactive species
Authors: Stanislawski Lena , Lefeuvre Mathieu , Bourd Katia , Soheili‐Majd Esmat , Goldberg Michel , Périanin Axel 
Published: August 2003

AbstractTriethylene glycol dimethacrylate (TEGDMA) is a dentin‐bonding agent and a major component of various dental restorative biomaterials. TEGDMA monomers are released from dental resins and induce dental pulp inflammation and necrosis. In this study, we have investigated the mechanism of TEGDMA–induced cytotoxicity of fibroblasts. Treatment of cultured human gingival and pulpal fibroblasts with 0.1–3 mM of TEGDMA for 24 h induced a concentration–dependent and variable cytotoxic effect. Fifty percent of toxicity (TC50) was obtained with 1.2 ± 0.9 and 2.6 ± 1.1 mM of TEGDMA for gingival and pulpal fibroblasts, respectively. Moreover, TEGDMA‐induced cytotoxicity was associated with an early and drastic depletion of cellular glutathione (GSH), which started at 15–30 min and was almost complete at 4–6 h. Antioxidants, such as Trolox (0.01 mM), ascorbate (0.2 mM), and N‐acetylcysteine (NAC) (5 mM) prevented the TEGDMA‐induced cytotoxicity while GSH depletion was partially inhibited. Finally, a late production of reactive oxygen species (ROS) occurred in fibroblasts treated with TEGDMA for 3–4 h, as determined by 2′,7′‐dichlorofluorescein fluorescence, and was completely inhibited by Trolox (5 μM). The data show that TEGDMA induced a drastic GSH depletion followed by production of ROS, which may contribute to the toxicity of gingival and pulpal fibroblasts. Antioxidants, such as NAC, ascorbate, and particularly Trolox, appear useful in preventing cell damage mediated by resin‐containing dental restorative materials. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 476–482, 2003
LS[7](3,5,11( exists
Authors: Eslami Ziba 
Published: August 2003

AbstractIn this article, we employ trades to construct an instance of an LS[7](3,5,11) which is the smallest unresolved LS[7](3,k,v) [9]. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 312–316, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jcd.10021