bluuebunny/crossref_metadata_2025_split huggingface dataset:
Different behavior of SCE‐eliciting lesions induced by low and high doses of busulfan
Authors: Morales‐Ramírez Pedro , González‐Beltrán Francisco 
Published: September 2007

AbstractOur previous studies suggested a dose‐dependent transition in the types of DNA lesions induced by busulfan, as measured using the comet assay and by micronuclei analyses. The aim of the present study was to investigate the dose‐dependent induction of different sister‐chromatid exchange‐eliciting lesions; lesions were distinguished by their efficiency in producing sister‐chromatid exchange (SCE), and by their reparability during G1. Synchronously dividing murine salivary gland cells were assayed in vivo. Groups of mice were intraperitoneally injected with either 30 or 80 μmol busulfan/kg body weight solution at early or late G1. The rate of SCE/μmol busulfan/kg body weight obtained by exposure at late G1 with the high dose was twice that of the low dose. SCE induction during early G1 was higher than at late G1 with both doses; only the low‐dose response was statistically significant. The frequency distribution of SCEs per cell demonstrated that cells exposed at the late G1 phase showed typical profiles that closely fit a Gaussian curve. However, an irregular profile was obtained for cells treated during early G1, which showed some cells with high‐SCE frequency. Cells treated in early G1 have more time to repair lesions before DNA synthesis; therefore, the results suggest that instead of repair, secondary SCE‐eliciting lesions during G1 were produced, especially at the lower dose. The results obtained in this study indicate that there are dose‐dependent differences in the types of SCE‐eliciting lesions induced by busulfan. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Collocated finite volume schemes for the simulation of natural convective flows on unstructured meshes
Authors: Chénier Eric , Eymard Robert , Herbin Raphaèle , Touazi Ouardia 
Published: September 2007

AbstractWe describe here a collocated finite volume scheme that was recently developed for the numerical simulation of the incompressible Navier–Stokes equations on unstructured meshes, in two or three space dimensions. We recall its convergence in the case of the linear Stokes equations, and we prove a convergence theorem for the case of the Navier–Stokes equations under the Boussinesq hypothesis. We then present several numerical studies. A comparison between a cluster‐type stabilization technique and the more classical Brezzi–Pitkäranta method is performed, the numerical convergence properties are presented on both analytical solutions and benchmark problems, and the scheme is finally applied to the study of the natural convection between two eccentric cylinders. Copyright © 2007 John Wiley & Sons, Ltd.
Parameter estimation for a three‐dimensional numerical barotropic tidal model with adjoint method
Authors: Zhang Jicai , Lu Xianqing 
Published: September 2007

AbstractThe parameters of a three‐dimensional (3‐D) barotropic tidal model are estimated using the adjoint method. The mode splitting technique is employed in both forward and adjoint models. In the external mode, the alternating direction implicit method is used to discretize the two‐dimensional depth‐averaged equations and a semi‐implicit scheme is used for the 3‐D internal mode computations. In this model the bottom friction is expressed in terms of bottom velocity which is different from the previous works. Besides, the bottom friction coefficients (BFCs) are supposed to be spatially varying, i.e. the BFC at some grid points are selected as the independent BFC, while the BFC at the other grid points can be obtained through linear interpolation with these independent BFCs. On the basis of the simulation of M2 tide in the Bohai and North Yellow Seas (BNYS), twin experiments are carried out to invert the prescribed distributions of model parameters. The parameters inverted are the
Fourier coefficients of open boundary conditions (OBCs), the BFC and the vertical eddy viscosity profiles. In these twin experiments, the real topography of BNYS is installed. The ‘observations’ are produced by the tidal model and recorded at the position of TOPEX/Poseidon altimeter data, tidal gauge data and current data. The experiments discuss the influence of initial guesses, model errors and data number. The inversion has obtained satisfactory results and the prescribed distributions have been successfully inverted. The results indicate that the inversion of BFC is more sensitive to data error than that of OBC and the vertical eddy viscosity profiles. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of macromer molecular weight and chemistry on poly(β‐amino ester) network properties and initial cell interactions
Authors: Brey Darren M. , Erickson Isaac , Burdick Jason A. 
Published: September 2007

AbstractA library of photocrosslinkable poly(β‐amino ester)s (PBAEs) was recently synthesized to expand the number of degradable polymers that can be screened and developed for a variety of biological applications. In this work, the influence of variations in macromer chemistry and macromer molecular weight (MMW) on network reaction behavior, overall bulk properties, and cell interactions were investigated. The MMW was controlled through alterations in the initial diacrylate to amine ratio (≥1) during synthesis and decreased with an increase in this ratio. Lower MMWs reacted more quickly and to higher double bond conversions than higher MMWs, potentially due to the higher concentration of reactive groups. Additionally, the lower MMWs led to networks with higher compressive and tensile moduli that degraded slower than networks formed from higher MMWs because of an increase in the crosslinking density and decrease in the number of degradable units per crosslink. The adhesion and spreading of osteoblast‐like cells on polymer films was found to be dependent on both the macromer chemistry and the MMW. In general, the number of cells was similar on networks formed from a range of MMWs, but the spreading was dramatically influenced by MMW (higher spreading with lower MMWs). These results illustrate further diversity in photocrosslinkable PBAE properties and that the chemistry and macromer structure must be carefully selected for the desired application. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Biodegradable microparticles and fiber fabrics for sustained delivery of cisplatin to treat C6 glioma in vitro
Authors: Xie Jingwei , Tan Ruo Shan , Wang Chi‐Hwa 
Published: September 2007

AbstractThe duration of cisplatin release from most of the drug delivery devices seemed to be shorter than 14 days except large microparticles. The objective of this study was to fabricate and characterize cisplatin‐loaded PLA microparticles, PLA/PLGA (30/70) composite microparticles, and fibers as formulations for long‐term sustained delivery of cisplatin to treat C6 glioma in vitro by electrospray and electrospinning techniques. Cisplatin‐loaded biodegradable microparticles with particle size of around 5 μm and fiber fabrics with diameter of 0.5–1.7 μm were obtained using electrospray and electrospinning techniques. Encapsulation efficiency and in vitro release of formulations were measured by ICP‐OES. The encapsulation efficiency for different samples of microparticles was approximately from 33% to 72% and the fiber fabrics had encapsulation efficiency greater than 90%. Cisplatin‐loaded microparticles showed typical characteristics of cisplatin release profile: a large initial burst followed by a sustained slow release of 35 days. The composite PLA/PLGA (30/70) microparticles could reduce the initial burst release of cisplatin because of their core–shell structures. In contrast, more than 75 days sustained release could be achieved by fiber fabric formulations without large initial burst. MTT assay was used to quantify the cytotoxicity of different formulations against C6 glioma cells. Microparticle formulations had slightly higher cytotoxicity than free drug. In contrast, the cytotoxicity of fiber fabrics formulation was around 4 times higher than of the free drug based on the actual amount of drug released. The microparticle and fiber fabric formulations presented may be promising for the sustained delivery of cisplatin to eliminate the undesired side effects caused by direct injection of cisplatin solution in systemic administration. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/poly(ϵ‐caprolactone) blends for tissue engineering applications in the form of hollow fibers
Authors: Chiono Valeria , Ciardelli Gianluca , Vozzi Giovanni , Sotgiu Maria Giulia , Vinci Bruna , Domenici Claudio , Giusti Paolo 
Published: September 2007

AbstractIn this work, hollow fibers to be used as guides for tissue engineering applications were produced by dry‐jet‐wet spinning of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/poly(ϵ‐caprolactone) (PHBHV/PCL) solutions in chloroform with various weight ratios between the components (PHBHV/PCL 100/0; 80/20; 60/40; 50/50; 40/60; 20/80; 0/100 w/w). Fibers obtained from PHBHV/PCL blends had a low degree of surface and bulk porosity, depending on composition. Physicochemical characterization involving scanning electron microscopy and differential scanning calorimetry (DSC) showed that PHBHV/PCL blends are compatible. Interactions between blend components were studied by Fourier transform infrared total reflectance spectroscopy, DSC analysis, and polarized optical microscopy analysis. Homogeneity of blend composition was assessed by IR‐chemical imaging analysis. PHBHV/PCL samples were found to be weakly hydrophilic and their biocompatibility was proved by in vitro tests using mouse fibroblasts. Mechanical properties of PHBHV/PCL blends were investigated by stress–strain tests, showing an increasing ductility of blend samples with increasing PCL amount. Hollow fibers supported fibroblasts attachment and proliferation depending on composition and porosity degree. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Enhanced nerve regeneration through a bilayered chitosan tube: The effect of introduction of glycine spacer into the CYIGSR sequence
Authors: Wang Wei , Itoh Soichiro , Matsuda Atsushi , Aizawa Tomoyasu , Demura Makoto , Ichinose Shizuko , Shinomiya Kenichi , Tanaka Junzo 
Published: September 2007

AbstractWe have developed a novel bilayered chitosan tube that comprises an outer layer of chitosan film and an inner layer of chitosan nonwoven nano/microfiber mesh. The tube is fabricated with an electrospinning method. We characterized the microstructure and mechanical properties of this material. We introduced glycine spacers into the CYIGSR sequence, domain of laminin‐1 that enhances Schwann cells migration and attachment, as well as neural outgrowth, resulting in the amino acid sequences CGGYIGSR and CGGGGGGYIGSR. These peptides were covalently bound to the nano/microfiber mesh surface of the chitosan tube to examine the effects of peptide mobility on nerve regeneration. Scaffolds constructed from these bilayered chitosan tubes were grafted to bridge injured sciatic nerve. Isografting was performed as a control. These scaffolds were removed 5 and 10 weeks after implantation for histological analysis. Nerve regeneration into chitosan tubes, on which the CGGGGGGYIGSR peptide was immobilized, exhibited efficacy similar to that of the isograft and represent a promising candidate for promoting peripheral nerve repair. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Bone regeneration using a naturally grown HA/TCP carrier loaded with rh BMP‐2 is independent of barrier‐membrane effects
Authors: Schopper C. , Moser D. , Spassova E. , Goriwoda W. , Lagogiannis G. , Hoering B. , Ewers R. , Redl H. 
Published: September 2007

AbstractThe present study investigated whether bone regeneration and biomaterial replacement would be improved by loading of biogenous biphasic biomaterial scaffolds (HA/TCP ratio 30/70) with rhBMP‐2, and whether the placement of three barrier membranes differing in structure and porosity (prototyped SLA Ti specimens, GORE RESOLUT Adapt specimens, and titanized TiMESH light specimens) would have a synergistic effect. A rabbit calvarial model was used for the implantation studies. Histological specimens were obtained after 12 weeks and evaluated quantitatively for differences between the various material combinations. Loading of the biomaterials with rhBMP‐2 significantly enhanced the amount of regenerated bone and caused a pronounced biomaterial replacement. While BMP‐induced bone had formed uniformly over the surgical defects, bone regeneration in the absence of BMP depends on bone promotion from the margins of the defects toward the center. No positive effect on bone regeneration was seen for any of the placed barrier membranes. While the present study had shown that rhBMP‐2 loading significantly increases bone regeneration using the investigated biomaterial, barrier‐membrane placement may be useful in predetermining the final shape of the regenerative site but provides no additional beneficial impact on the amount and quality of the bone regeneration induced by rhBMP‐2. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Synthesis of partial‐stabilized cement (PSC) via sol–gel process
Authors: Wang Wen‐Hsi , Lee Yuan‐Ling , Lin Chun‐Pin , Lin Feng‐Huei 
Published: September 2007

AbstractThe traditional method of preparing partial‐stabilized cement (PSC), which is a kind of calcium silicate cement, is through power mixing method. Low reaction efficiency and initial strength limited the application of PSC as a dental root‐end filling material. This study provides a one‐step sol–gel process for the synthesis of PSC. A complexing ligand is used for tuning down the activity of aluminum sec‐butoxide (ASB) in order to avoid possible self‐polymerization. After the modification with complex ligand, there is no residue of reactant observed on the analysis of SDT, and bonding between metal atoms is observed in the FTIR spectrum. Each component of PSC is identified using XRD. The hydration product, which is called portlandite, of sol–gel‐synthesized PSC is observed after 1 day of hydration, and crystallinity of portlandite increases much faster than that of traditional PSC. The initial strength of sol–gel‐synthesized PSC achieves detectable level 24 h earlier than that of traditional PSC; microhardness value of sol–gel‐synthesized PSC at 7th day is 2.98 HV, which is much higher than that of traditional PSC (2.05 HV). PSC is successfully synthesized and the initial strength of PSC is improved by this modified sol–gel process. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
A novel system for water soluble protein encapsulation with high efficiency: “Micelles enhanced” polyelectrolyte capsules
Authors: Li Xiaodong , Li Xiaohui , Zhang Jianxiang , Zhao Shifang , Shen Jiacong 
Published: September 2007

AbstractNovel “micelles enhanced” polyelectrolyte (PE) capsules based on functional templates of hybrid calcium carbonate were fabricated. Evidences suggested that the structure of capsule wall was different from that of conventional PE capsules, and the wall permeability of these PE capsules changed significantly. Lysozyme, a positively charged protein in neutral solution, was studied as a model protein to be encapsulated into the “micelles enhanced” PE capsules. Confocal laser scanning microscope was used to observe the entrapping process in real time, while UV‐Vis spectroscope and scanning force microscope measurements suggested the high efficiency of encapsulation. In addition, the fluorescence recovery after photobleaching technique was employed to determine the existence form of deposited molecules. Further studies showed even negatively charged water‐soluble peptides or proteins can be encapsulated into these hybrid capsules by modulating the pH value in bulk solution under its isoelectronic point as well. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Nonfouling biomaterials based on polyethylene oxide‐containing amphiphilic triblock copolymers as surface modifying additives: Solid state structure of PEO‐copolymer/polyurethane blends
Authors: Tan J. , Brash J. L. 
Published: September 2007

AbstractThree novel polyethylene oxide‐containing amphiphilic triblock copolymers (PEO‐PU‐PEO) with PEO MWs 550, 2000, and 5000, were blended with a segmented polyurethane (PU). It was expected that the block copolymers would act as surface modifiers to produce surfaces rich in PEO. The solid state properties of the PEO‐copolymer/PU blends were studied by infrared spectroscopy, differential scanning calorimetry, and tensile stress–strain measurements. Infrared analysis showed no significant hydrogen bonding between the PEO blocks of the copolymers and the PU matrix. Differential scanning calorimetry data indicated that for copolymer content up to 5 wt % the microphase structure of the blends was indistinguishable from that of the unmodified PU matrix; for copolymer content of 10% or greater, the blends showed phase separated structures. Similarly the tensile stress–strain properties of the blends were essentially the same as those of the matrix up to 5 wt % copolymer. At higher copolymer content, however, the tensile strength decreased with increasing content of the copolymers; for a given copolymer content the change in tensile properties increased with increasing PEO MW. The structures of the 20% blends were also investigated after extraction with toluene (copolymers soluble, matrix insoluble). Bulk compositional change upon extraction was determined by nuclear magnetic resonance spectroscopy. Surface compositional change was studied by X‐ray photoelectron spectroscopy and water contact angles. Surface morphology was observed using scanning electron microscopy and atomic force microscopy. It was shown that the copolymers were removed from the blends by extraction and that the extent of removal increased with decreasing MW of the PEO block. After toluene extraction, the blend surfaces showed advancing water contact angle and surface elemental composition similar to those of the PU matrix. However in contrast to the relatively smooth matrix surface, the extracted blend surfaces were “decorated” with lacunae or pits. Consistent with the weight loss trends, the extent of pitting was greater for the copolymers having shorter PEO blocks, suggesting that surface enrichment of the copolymers increased with decreasing MW of the copolymers. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Nonfouling biomaterials based on polyethylene oxide‐containing amphiphilic triblock copolymers as surface modifying additives: Protein adsorption on PEO‐copolymer/polyurethane blends
Authors: Tan J. , McClung W. G. , Brash J. L. 
Published: September 2007

AbstractSurface modification of a segmented polyurethane was achieved by blending with novel PEO‐containing amphiphilic triblock copolymers (PEO‐polyurethane‐PEO). Three copolymers having different PEO MW (550, 2000, 5000) were used as surface modification additives. The protein resistance of the blend surfaces was evaluated using radiolabeling methods. On the blends of copolymers with PEO blocks of MW 2000 and 5000, fibrinogen adsorption from physiologic buffer decreased with increasing copolymer content up to 20 wt%. On the blends with PEO blocks of MW 550, resistance to adsorption for a given copolymer content was much greater. For all three blend types at 20% copolymer content, reductions in adsorption compared to the unmodified PU matrix were greater than 95%. Reductions in adsorption were similar for the 20% blends and surfaces prepared by coating the copolymers directly on the matrix, suggesting that the 20% blend surfaces were completely covered by copolymer. At low copolymer content (≤10 wt %), fibrinogen adsorption decreased with decreasing PEO block length. This was probably due to increasing surface coverage of the copolymers with decreasing block length. It is therefore concluded that surface density of PEO is more important than PEO MW for the protein resistance of these surfaces. Lysozyme, a much smaller protein, showed adsorption trends similar to fibrinogen. The adsorption of fibrinogen and lysozyme from binary solutions to blends of the copolymer with PEO blocks of 2000 MW was investigated to probe the effects of protein size on adsorption resistance. Fibrinogen and lysozyme showed similar fractional decreases in adsorption relative to the PU matrix independent of the surface density of PEO. However lysozyme was enriched in the surface relative to the solution, that is, it was adsorbed preferentially to fibrinogen. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Microtensile strain on the corrosion performance of diamond‐like carbon coating
Authors: Lee Seung‐Hwan , Kim Jung‐Gu , Choi Heon‐Woong , Lee Kwang‐Ryeol 
Published: September 2007

AbstractHydrogenated diamond‐like carbon films (a‐C:H DLC) were deposited on STS 304 substrates for the fabrication of vascular stents by means of the r.f. plasma‐assisted chemical vapor deposition technique. This study provides reliable and quantitative data for the assessment of the effect of strain on the corrosion performance of DLC‐coated systems in the simulated body fluid obtained through electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy) and surface analysis (scanning electron microscopy). The electrolyte used in this test was 0.89% NaCl solution at pH 7.4 and 37°C. It was found that the corrosion resistance of the plastically deformed DLC coating was insufficient for use as a protective film in a corrosive body environment. This is due to the increase in the delamination area and degradation of the substrate's corrosion properties with increasing tensile deformation. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Cisplatin‐loaded Au–Au2S nanoparticles for potential cancer therapy: Cytotoxicity, in vitro carcinogenicity, and cellular uptake
Authors: Ren Lei , Huang Xiao‐Li , Zhang Bin , Sun Li‐Ping , Zhang Qi‐Qing , Tan Mei‐Chee , Chow Gan‐Moog 
Published: September 2007

AbstractCisplatin is one of the most effective cytotoxic agents against cancers. Its usage, however, is limited because of severe resistance and systemic toxicity. A formulation of cisplatin‐loaded Au–Au2S nanoparticles (NPs) with near‐IR (NIR) sensitivity is reported to partly overcome this limitation in this paper. NIR sensitive Au–Au2S NPs were successfully synthesized by the reduction of tetrachloroauric acid (HAuCl4) using sodium sulfide (Na2S), and cisplatin was loaded onto Au–Au2S NPs via a MUA (11‐mercaptoundecanoic acid) layer. To further investigate the biological safety of cisplatin‐loaded Au–Au2S NPs, three different cell lines were used to investigate the acute cytotoxicity and the long‐term potential carcinogenicity in vitro. Cisplatin‐loaded Au–Au2S NPs were also tested for limited hemocompatibility in vitro. Our in vitro short and long‐term data provided preliminary evidence suggesting that cisplatin‐loaded Au–Au2S NPs with NIR sensitivity are nontoxic below the maximum recommended dosage. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008