bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐strength, in situ‐setting calcium phosphate composite with protein release
Authors: Weir Michael D. , Xu Hockin H.K. 
Published: August 2007

AbstractThe aim of this study was to develop a mechanically‐strong calcium phosphate cement (CPC) with protein release. Chitosan was used to strengthen CPC and control protein release. Mass fraction of protein release = mass of released protein/mass of total protein incorporated into the specimen. Flexural strength (mean ± sd; n = 6) of CPC containing 100 ng/mL of protein increased from 8.0 ± 1.4 MPa with 0% chitosan, to 19.8 ± 1.4 MPa with 15% chitosan (p < 0.05). The latter exceeded the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. When the chitosan mass fraction was increased from 0% to 10% and 15%, protein release varied from 0.60 ± 0.03 to 0.41 ± 0.04, and to 0.23 ± 0.07, respectively (p < 0.05). When powder:liquid ratio increased from 2:1 to 3:1 and 4:1, protein release changed from 0.89 ± 0.10 to 0.41 ± 0.04, and to 0.23 ± 0.07, respectively p < 0.05. Therefore, chitosan content and powder:liquid ratio successfully controlled the protein release. The protein release mass fraction, M, was related to CPC porosity P by: M = 16.9 P4.5. In summary, a mechanically‐strong CPC with controlled protein release was formulated. Protein release was proportional to CPC porosity. The in situ‐hardening, nano‐apatite composite may have potential for bone tissue engineering, especially when both mechanical strength and controlled release of therapeutic/bioactive agents are needed. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Synthesis, characterization, and hydrolytic degradation behavior of a novel biodegradable pH‐sensitive hydrogel based on polycaprolactone, methacrylic acid, and poly(ethylene glycol)
Authors: Chao Guo Tao , Qian Zhi Yong , Huang Mei Juan , Kan Bing , Gu Ying Chun , Gong Chang Yang , Yang Jin Liang , Wang Ke , Dai Mei , Li Xing Yi , Gou Ma Ling , Tu Ming Jing , Wei Yu Quan 
Published: August 2007

AbstractIn this work, a new kind of biodegradable pH‐sensitive hydrogel was successfully synthesized by UV‐initiated free radical polymerization. The obtained hydrogel was characterized by 1H NMR and FTIR. Swelling behavior in different aqueous media and pH responsivity of the hydrogels were studied in detail as well. With increase in pH from 1.2 to 7.2, swelling ratio of the hydrogel increased. The morphology was observed by scanning electron microscopy, and the hydrolytic degradation behavior was also investigated in this work. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Biodegradable PCL scaffolds with an interconnected spherical pore network for tissue engineering
Authors: Izquierdo R. , Garcia‐Giralt N. , Rodriguez M.T. , Cáceres E. , García S.J. , Gómez Ribelles J.L. , Monleón M. , Monllau Joan C. , Suay J. 
Published: August 2007

AbstractA technique for producing controlled interconnected porous structures for application as a tissue engineering scaffold is presented in this article. The technique is based on the fabrication of a template of interconnected poly(ethyl methacrylate) (PEMA) microspheres, the introduction of a biodegradable polymer, poly‐ϵ‐caprolactone (PCL), and the elimination of the template by a selective solvent. A series of PCL scaffolds with a porosity of 70% and pore sizes up to 200 μm were produced and characterized (both thermally and mechanically). Human chondrocytes were cultured in monolayer on bulk PCL disks or seeded into porous PCL scaffolds. Cell adhesion, viability, proliferation, and proteoglycan (PG) synthesis were tested and compared with monolayer cultures on tissue‐treated polystyrene or pellet cultures as reference controls. Cells cultured on PCL disks showed an adhesion similar to that of the polystyrene control (which allowed high levels of proliferation). Stained scaffold sections showed round‐shaped chondrocyte aggregates embedded into porous PCL. PG production was similar to that of the pellet cultures and higher than that obtained with monolayer postconfluence cultures. This shows that the cells are capable of attaching themselves to PCL. Furthermore, in porous PCL, cells maintain the same phenotype as the chondrocytes within the native cartilage. These results suggest that PCL scaffolds may be a suitable candidate for chondrocyte culture. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Oxidized NiTi surfaces enhance differentiation of osteoblast‐like cells
Authors: Michiardi A. , Engel E. , Aparicio C. , Planell J. A. , Gil F. J. 
Published: August 2007

AbstractA new oxidation treatment (OT) on NiTi shape memory alloys was developed in a previous work. This OT treatment significantly decreases Ni ion release into the exterior medium, and therefore is thought to be beneficial for NiTi cytocompatibility. As to confirm this expectation, the in vitro response of MG63 osteoblast‐like cells cultured on untreated and oxidized NiTi surfaces was studied. An adhesion test at 1, 4, and 8 h of incubation was performed. Statistical differences were evidenced at 1 h of adhesion depending on the surface treatment and chemical composition of the substrate. However, at larger times of study, there were no statistically significant differences between untreated and oxidized surfaces. The proliferation test (until 9 days) showed that untreated and oxidized NiTi surfaces are not cytotoxic for MG63 cells. The differences of adhesion at short times did not affect the proliferation of MG63 cells. However, after 48 h of stimulation with ascorbic acid and dexamethasone, the MG63 cells cultured on oxidized surfaces showed higher alkaline phosphatase activity and osteocalcin levels. The improvement of osteoblast differentiation due to OT treatment could accelerate bone formation, and, therefore, could allow earlier loading of NiTi devices used in dental and orthopedic applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Structural evolution and adhesion of titanium oxide film containing phosphorus and calcium on titanium by anodic oxidation
Authors: Lin C. S. , Chen M. T. , Liu J. H. 
Published: August 2007

AbstractThis study investigated the microstructure evolution and defects of the titanium oxide layer containing calcium (Ca) and phosphorus (P) formed by anodic oxidation in a solution containing Ca and P compounds. Results show that the anodic film exhibited a two‐layer structure: a pore‐containing amorphous titanium oxide layer dispersed with nano‐sized crystallites formed prior to sparking, and a porous overlay dotted with craters formed after sparking. Ca and P were predominantly incorporated in the porous overlay, in which the amorphous region contained more Ca and P than the crystalline region regardless of the anodizing voltages. Moreover, the ratio of amorphous to crystalline regions in the porous overlay changed insignificantly with anodizing voltage. Increasing anodizing voltage enhanced the incorporation of Ca and P in the anodic film, but deteriorated the adhesion of the anodic film to the substrate. This deterioration was related to two inherent adhesive weaknesses: the aligned pores in the titanium oxide layer and the craters in the major overlay, signifying that a new anodic oxidation process that can produce high Ca‐ and P‐containing oxide film at relatively‐low anodizing voltages, i.e. ∼200 V, is a necessity. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Fibrinogen adsorption onto 316L stainless steel under polarized conditions
Authors: Gettens Robert T.T. , Gilbert Jeremy L. 
Published: August 2007

AbstractAdsorption of the plasma protein fibrinogen onto electrically polarized 316L stainless steel was observed and quantified using both in situ and ex situ atomic force microscopy (AFM) techniques. Significant differences in fibrinogen adsorption were observed across voltages. Ex situ studies showed significantly lower area coverage (θ) and height of adsorbed Fb on cathodically polarized surfaces when compared to anodically polarized surfaces. Conformational differences in the protein may explain the distinctions in Fb surface area coverage (θ) and height between the anodic and cathodic cases. In situ studies showed significantly slower kinetics of Fb adsorption onto surfaces below −100 mV (vs. Ag/AgCl) compared to surfaces polarized above −100 mV. Electrochemical current density data showed large charge transfer processes (∼1 × 10−5 to 1 × 10−4 A/cm2) taking place on the 316L SS surfaces at voltages below −100 mV (vs. Ag/AgCl). These relatively large current densities point to flux of ionic species away from the surface as a major source of the reduction in adsorption kinetics rather than just hydrophilic or electrostatic effects. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Time‐dependent electrochemical characterization of the corrosion of a magnesium rare‐earth alloy in simulated body fluids
Authors: Rettig Ralf , Virtanen Sannakaisa 
Published: August 2007

AbstractThe electrochemistry of the corrosion process of a magnesium rare‐earth‐alloy is studied in detail in simulated body fluid (m‐SBF) over the first 5 days. The aim is to investigate the corrosion mechanism under in vitro conditions. For this purpose we also used electrolytes that contain only some of the components of SBF, they were compared to SBF to investigate the influence of the different ions in SBF. The influence of albumin on the corrosion process was studied with a solution containing m‐SBF and albumin in physiological concentration. For this study, impedance spectroscopy series measurements were performed. Additional results were gained from polarization curves. We conclude from the study that the corrosion resistance is significantly lower in m‐SBF than in simple isotonic NaCl‐solution. Albumin may form a blocking layer on the surface in the first hours of exposure. The formed corrosion layers consisting of amorphous apatite have only a low protective ability. Further results show that the corrosion processes in SBFs follow a linear time‐law. The results elucidate critical factors and mechanisms of the electrochemical corrosion process of magnesium rare‐earth alloys in SBFs, this understanding is crucial for a successful application of Mg alloys in biomedical applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Increased osteoblast adhesion on nanoparticulate calcium phosphates with higher Ca/P ratios
Authors: Ergun Celaletdin , Liu Huinan , Webster Thomas J. , Olcay Ercan , Yılmaz Şafak , Sahin Filiz C. 
Published: August 2007

AbstractThe biological properties of calcium phosphate‐derived materials are strongly influenced by changes in Ca/P stoichiometry and grain size, which have not yet been fully elucidated to date. For this reason, the objective of this in vitro study was to understand osteoblast (bone forming cells) adhesion on nanoparticulate calcium phosphates of various Ca/P ratios. A group of calcium phosphates with Ca/P ratios between 0.5 and 2.5 were obtained by adjusting the Ca/P stoichiometry of the initial reactants necessary for calcium phosphate precipitation. For samples with 0.5 and 0.75 Ca/P ratios, tricalcium phosphate (TCP) and Ca2P2O7 phases were observed. In contrast, for samples with 1.0 and 1.33 Ca/P ratios, the only stable phase was TCP. For samples with 1.5 Ca/P ratios, the TCP phase was dominant, however, small amounts of the hydroxyapatite (HA) phase started to appear. For samples with 1.6 Ca/P ratios, the HA phase was dominant. Last, for samples with 2.0 and 2.5 Ca/P ratios, the CaO phase started to appear in the HA phase, which was the dominant phase. Moreover, the average nanometer grain size, porosity (%), and the average pore size decreased in general with increasing Ca/P ratios. Most importantly, results demonstrated increased osteoblast adhesion on calcium phosphates with higher Ca/P ratios (up to 2.5). In this manner, this study provided evidence that Ca/P ratios should be maximized (up to 2.5) in nanoparticulate calcium phosphate formulations to increase osteoblast adhesion, a necessary step for subsequent osteoblast functions such as new bone deposition. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Different regulation of hepatocyte behaviors between natural extracellular matrices and synthetic extracellular matrices by hepatocyte growth factor
Authors: Hoshiba Takashi , Wakejima Mai , Cho Chong‐Su , Shiota Goshi , Akaike Toshihiro 
Published: August 2007

AbstractThe roles of growth factors and extracellular matrices (ECMs) in regulation of hepatocyte behaviors are very important for the establishment of liver‐tissue engineering. Especially, collaboration between growth factors and ECMs is a big concern for liver‐tissue engineering. In this study, the hepatocyte responses by hepatocyte growth factor (HGF) were compared between natural ECMs and a synthetic galactose‐carrying polymer: poly(N‐p‐vinylbenzyl‐4‐O‐β‐D‐galactopyranosyl‐D‐gluconamide) (PVLA). Hepatocytes underwent proliferation on type I collagen‐ and fibronectin‐coated surfaces in the presence of HGF, whereas hepatocytes formed spheroid on laminin‐1‐, PVLA‐, and poly‐L‐lysine (PLL)‐coated surfaces in the presence of HGF without the activation of proliferation. HGF accelerated ECM deposition, especially laminin‐10/11, beneath the hepatocytes cultured on PVLA‐ and PLL‐coated surfaces and the deposited laminin‐10/11 activated integrin signaling to collaborate with HGF signaling. Therefore, the deposited ECM molecules should be focused to clear the mechanism of hepatocyte behaviors in the presence of HGF. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Considering the zebrafish in a comparative context
Authors: Schilling Thomas F. , Webb Jacqueline 
Published: August 2007

AbstractThis article introduces a special issue on zebrafish biology that attempts to integrate developmental genetics with comparative studies of other fish species. For zebrafish researchers, comparative work offers a better understanding of the evolutionary history of their model system. Comparative biologists can gain many insights from the developmental and genetic mechanisms revealed in zebrafish that have contributed to the huge range of morphological variation among fishes that has arisen over millions of years. These ideas are considered here in various contexts, including systematics, genome organization and the development of the nervous system, pigmentation, craniofacial skeleton and dentition. Studies of the zebrafish in phylogenetic context provide an opportunity for synergy between communities using these two fundamentally different approaches. J. Exp. Zool. (Mol. Dev. Evol.) 308B:515–522, 2007. © 2007 Wiley‐Liss, Inc.
Replication‐competent, oncolytic herpes simplex virus type 1 mutants induce a bystander effect following ganciclovir treatment
Authors: Luo Chenhong , Mori Isamu , Goshima Fumi , Ushijima Yoko , Nawa Akihiro , Kimura Hiroshi , Nishiyama Yukihiro 
Published: August 2007

AbstractCells expressing herpes simplex virus (HSV) thymidine kinase (tk) are killed by ganciclovir (GCV). Adjacent cells without HSV‐tk also die, a phenomenon known as the ‘bystander effect’. However, there is no evidence that replication‐competent HSV induces a bystander effect in the presence of GCV. Therefore, we investigated the bystander effect in HEp‐2 cells infected with replication‐competent, oncolytic HSV‐1 mutants, hrR3 and HF10. In cells infected at a multiplicity of infection (MOI) of 3, GCV did not induce apoptosis. At low MOIs of 0.3 and 0.03, however, a number of adjacent, uninfected cells apoptosed following GCV treatment. Irrespective of GCV treatment, HEp‐2 cells expressed minimal levels of connexin 43 (Cx43). However, Cx43 expression was enhanced by GCV in response to infection with HF10 at an MOI of 0.3, but not at an MOI of 3. Expression of other proteins involved in gap junctions, including Cx26 and Cx40, was not augmented under these conditions. The PKA and PI3K signal transduction pathways are likely involved in enhanced Cx43 expression as inhibitors of these pathways prevented Cx43 upregulation. These results suggest that infection with replication‐competent HSV‐1 induces the bystander effect in cells treated with GCV because of efficient intercellular transport of active GCV through abundant gap junctions. Copyright © 2007 John Wiley & Sons, Ltd.
On graphs with subgraphs having large independence numbers
Authors: Alon Noga , Sudakov Benny 
Published: August 2007

AbstractLet G be a graph on n vertices in which every induced subgraph on ${s}={\log}^{3}\, {n}$ vertices has an independent set of size at least ${t}={\log}\, {n}$. What is the largest ${q}={q}{(n)}$ so that every such G must contain an independent set of size at least q? This is one of the several related questions raised by Erdős and Hajnal. We show that ${q}{(n)}= \Theta({\log}^{2} {n}/{\log}\, {\log} \,{n})$, investigate the more general problem obtained by changing the parameters s and t, and discuss the connection to a related Ramsey‐type problem. © 2007 Wiley Periodicals, Inc. J Graph Theory 56: 149–157, 2007
Quantitative analysis with modern bioanalytical mass spectrometry and stable isotope labeling
Authors: Richards Dawn P. , Sojo Luis E. , Keller Bernd O. 
Published: August 2007

AbstractThe invention of new ionization techniques namely electrospray ionization and matrix‐assisted laser desorption/ionization combined with the development of novel mass spectrometer analyzers and evolving isotope‐ratio mass spectrometry have fueled the presence and use of modern mass spectrometric methodologies in many bioanalytical laboratories. Consequently, over the past two decades, a steadily increasing number of quantitative methods employing stable isotope labeling techniques have been reported, including prominent examples of methods to determine differential expression of proteins in disease studies, new‐born screening for metabolic disorders, and tracing drugs or dietary compounds and their respective metabolites. Labeling biomolecules for quantitative studies using mass spectrometry has several challenges, including potentially insufficient labeling efficiency, ionization suppression, chromatographic separation of labeled and non‐labeled compounds, and isotope exchange with the environment. It is not surprising that method development to minimize or eliminate existing limitations represents a very active and dynamic research area. Copyright © 2007 John Wiley & Sons, Ltd.
Small‐fiber involvement in spinobulbar muscular atrophy (Kennedy's disease)
Authors: Manganelli Fiore , Iodice Valeria , Provitera Vincenzo , Pisciotta Chiara , Nolano Maria , Perretti Anna , Santoro Lucio 
Published: August 2007

AbstractWe assessed the involvement of cutaneous innervation in two subjects with a molecularly confirmed diagnosis of spinobulbar muscular atrophy (SBMA) using antidromic nerve conduction studies, quantitative sensory testing, and sweat tests, as well as immunohistochemical techniques and confocal microscopy of glabrous and hairy skin biopsy. Both patients showed a marked reduction in amplitude of sensory action potentials and moderate or severe abnormalities of tactile thresholds and mechanical pain perception. A severe reduction of sweat drops on the Silastic imprint test and a widespread loss of small myelinated and unmyelinated fibers in hairy skin were also observed. Fiber loss involved either somatic or autonomic fibers and did not show any distal–proximal gradient. These results, together with loss of Meissner corpuscles and their large myelinated afferent fibers in glabrous skin, confirmed the extensive involvement of sensory neurons of large and small size and revealed an autonomic skin denervation in SBMA. Muscle Nerve, 2007
Random porosity fields and their influence on the stability of granular media
Authors: Andrade José E. , Baker Jack W. , Ellison Kirk C. 
Published: August 2007

AbstractIt is well established that the mechanical behavior of granular media is strongly influenced by the media's microstructure. In this work, the influence of the microstructure is studied by integrating advances in the areas of geostatistics and computational plasticity, by spatially varying the porosity on samples of sand. In particular, geostatistical tools are used to characterize and simulate random porosity fields that are then fed into a nonlinear finite element model. The underlying effective mechanical response of the granular medium is governed by a newly developed elastoplastic model for sands, which readily incorporates spatial variability in the porosity field at the meso‐scale. The objective of this study is to assess the influence of heterogeneities in the porosity field on the stability of sand samples. One hundred and fifty isotropic and anisotropic samples of dense sand are failed under plane‐strain compression tests using Monte Carlo techniques. Results from parametric studies indicate that the axial strength of a specimen is affected by both the degree and orientation of anisotropy in heterogeneous porosity values with anisotropy orientation having a dominant effect, especially when the bands of high porosity are aligned with the natural orientation of shear banding in the specimen. Copyright © 2007 John Wiley & Sons, Ltd.
Multivariate chromatographic fingerprint preparation and authentication of plant material from the genus Bauhinia
Authors: Soares Patricia Kaori , Scarminio Ieda Spacino 
Published: August 2007

AbstractMultivariate analysis and statistical mixture designs were used for chromatographic fingerprint preparation and authentication of the plant material of three species of the genus Bauhinia. The extracts were analysed by reversed‐phase high‐performance liquid chromatography. Mixture design gave an optimum solvent composition for extracting components from the plants of 36% dichloromethane, 17% ethanol and 47% ethyl acetate (by volume), while an optimum mobile phase for chromatographic analyses was found to be 27% methanol, 27% acetonitrile and 46% of water (by volume). Results from principal component analysis, hierarchical analysis and soft independent modelling by class analogy showed that Bauhinia candicans cannot be synonymous with B. forficata Link. It was also possible to trace the metabolic profile without identifying its chemical constituents and to determine a chromatographic discriminating region. The characteristics responsible for discrimination between B. candicans and B. forficata were more polar substances that presented peaks with retention times around 1.65 and 1.81 min. Copyright © 2007 John Wiley & Sons, Ltd.
The role of impurities in thermally stimulated luminescence of MgO:Mn2+ and MgO:V2+ crystals irradiated in a reactor
Authors: Kvatchadze V. , Dekanozishvili G. , Galustashvili M. , Kalabegishvili T. , Keratishvili N. , Zardiashvili D. 
Published: August 2007

AbstractThe high‐temperature thermally stimulated luminescence (TSL) of nominally pure MgO crystals and MgO crystals with excessive amounts of paramagnetic manganese and vanadium ions irradiated in a reactor has been studied. It was observed that the influence of impurity on the TSL of crystal is different at low and relatively high doses. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ultrasonic properties of glassy alloys in terms of complex wave elasticity
Authors: Fukuhara Mikio , Zhang Wei , Inoue Akihisa 
Published: August 2007

AbstractUsing ultrasonics, acoustic characteristics of Pd40Cu30P20, Zr55Cu30Al10Ni5, Zr65Pd12.5Ni10Al7.5Cu5, Cu55Zr30Ti10Pd5, Cu45Zr20Hf25Ag10 and Ti41.5Cu42.5Ni7.5Hf5Zr2.5Sn1 glassy alloys were examined in terms of complex elasticity. The order of bulk modulus (K), Lamé parameter (λ), Young (E) and shear (G) moduli of the glassy alloys shows the monopolistical character of the glassy alloys, except for polymers and rubbers. Poison's ratio correlates well to the anisotropy factor and the ratio G /K, accompanied by dilational and shear attenuation coefficients, showing characteristic one‐dimensional elastic deformability of the glassy alloys. The complex elasticity shows that the viscoelasticity of the glassy alloys is predominated by volumetric motion, associated with the complex waves. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)