bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vascularization and biocompatibility of scaffolds consisting of different calcium phosphate compounds
Authors: Rücker Martin , Laschke Matthias W. , Junker Dominic , Carvalho Carlos , Tavassol Frank , Mülhaupt Rolf , Gellrich Nils‐Claudius , Menger Michael D. 
Published: December 2007

AbstractScaffolds for tissue engineering of bone should mimic bone matrix and promote vascular ingrowth. Whether synthetic hydroxyapatite and acellular dentin, both materials composed from calcium phosphate, fulfill these material properties has not been studied yet. Therefore, we herein studied in vivo the host angiogenic and inflammatory response to these biomaterials. Porous scaffolds of hydroxyapatite and isogeneic acellular dentin were implanted into the dorsal skinfold chamber of balb/c mice. Additional animals received perforated implants of isogeneic calvarial bone displaying pores similar in size and structure to those of both scaffolds. Chambers of animals without implants served as controls. Angiogenesis and neovascularization as well as inflammatory leukocyte‐endothelial cell interaction and microvascular leakage were analyzed over a 14‐day time period using intravital fluorescence microscopy. Implantation of both hydroxyapatite and dentin scaffolds showed a slight increase in leukocyte recruitment compared with controls. This was associated with an elevation of microvascular permeability, which was comparable to that observed in response to isogeneic bone. In addition, hydroxyapatite as well as dentin scaffolds induced a marked angiogenic response, which resulted in complete vascularization of the implants until day 14. Of interest, in hydroxyapatite scaffolds, the newly formed capillaries were not as densely meshed as in dentin scaffolds, in which the functional capillary density was comparable to that measured in bone implants. Hydroxyapatite and, in particular, dentin scaffolds promote vascularization and exhibit a biocompatibility comparable to that of isogeneic bone. This may guarantee the rapid incorporation of these materials into the host tissue. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Magnetic nanoparticles for improving cell invasion in tissue engineering
Authors: Sasaki Takuro , Iwasaki Norimasa , Kohno Kenji , Kishimoto Mikio , Majima Tokifumi , Nishimura Shin‐Ichiro , Minami Akio 
Published: December 2007

AbstractIt has been widely recognized that cells are seeded onto only the superficial layer of three‐dimensional (3D) scaffolds in tissue engineering technology. This leads to tissue necrosis that occurs in the central part of 3D scaffolds. To solve this issue, an effective cell seeding technique into the central part of 3D scaffolds is required. Chitosan has characteristics of biocompatibility, biodegradability, and low‐toxicity. In this study, we developed novel magnetic nanoparticles (MNs) coated with chitosan for enhancing cellular invasion using magnetic force. Cell‐invasion efficiency was enhanced by introducing our novel MNs into cells and by the presence of magnetic force. This invasion efficacy depends on the degree of magnetic force. Matrix metalloproteinases and adhesion molecules that were upregulated in response to the attached nanoparticles and exposure to a magnetic force may also play a crucial role in improving cell‐invasive ability in this system. This current system can efficiently enhance cell seeding into the depth of the scaffold, increase subsequent cell–cell interactions and shorten the period of cell proliferation. This system is thought to be useful in the development of cell‐based strategies for the repair or replacement of tissue and other novel therapies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Functional characterization of P2Y1 versus P2X receptors in RBA‐2 astrocytes: Elucidate the roles of ATP release and protein kinase C
Authors: Weng Ju‐Yun , Hsu Tsan‐Ting , Sun Synthia H. 
Published: December 2007

AbstractA physiological concentration of extracellular ATP stimulated biphasic Ca2+ signal, and the Ca2+ transient was decreased and the Ca2+ sustain was eliminated immediately after removal of ATP and Ca2+ in RBA‐2 astrocytes. Reintroduction of Ca2+ induced Ca2+ sustain. Stimulation of P2Y1 receptors with 2‐methylthioadenosine 5′‐diphosphate (2MeSADP) also induced a biphasic Ca2+ signaling and the Ca2+ sustains were eliminated using Ca2+‐free buffer. The 2MeSADP‐mediated biphasic Ca2+ signals were inhibited by phospholipase C (PLC) inhibitor U73122, and completely blocked by P2Y1 selective antagonist MRS2179 and protein kinase C (PKC) activator phorbol 12‐myristate 13‐acetate (PMA) whereas enhanced by PKC inhibitors GF109203X and Go6979. Inhibition of capacitative Ca2+ entry (CCE) decreased the Ca2+‐induced Ca2+ entry; nevertheless, ATP further enhanced the Ca2+‐induced Ca2+ entry in the intracellular Ca2+ store‐emptied and CCE‐inhibited cells indicating that ATP stimulated Ca2+ entry via CCE and ionotropic P2X receptors. Furthermore, the 2MeSADP‐induced Ca2+ sustain was eliminated by apyrase but potentiated by P2X4 allosteric effector ivermectin (IVM). The agonist ADPβS stimulated a lesser P2Y1‐mediated Ca2+ signal and caused a two‐fold increase in ATP release but that were not affected by IVM whereas inhibited by PMA, PLC inhibitor ET‐18‐OCH3 and phospholipase D (PLD) inhibitor D609, and enhanced by removal of intra‐ or extracellular Ca2+. Taken together, the P2Y1‐mediated Ca2+ sustain was at least in part via P2X receptors activated by the P2Y1‐induced ATP release, and PKC played a pivotal role in desensitization of P2Y1 receptors in RBA‐2 astrocytes. J. Cell. Biochem. 104: 554–567, 2008. © 2007 Wiley‐Liss, Inc.
Carbon nanotube, graphene, nanowire, and molecule‐based electron and spin transport phenomena using the nonequilibrium Green's function method at the level of first principles theory
Authors: Kim Woo Youn , Kim Kwang S. 
Published: December 2007

AbstractBased on density functional theory, we have developed a program code to investigate the electron transport characteristics for a variety of nanometer scaled devices in the presence of an external bias voltage. We employed basis sets comprised of linear combinations of numerical type atomic orbitals, particularly focusing on k‐point sampling for the realistic modeling of the bulk electrode. The scheme coupled with the matrix version of the nonequilibrium Green's function method enables calculation of the transmission coefficients at a given energy and voltage in a self‐consistent manner as well as the corresponding current‐voltage (I‐V) characteristics. This scheme has advantages because it is applicable to large systems, easily transportable to different types of quantum chemistry packages, and extendable to time‐dependent phenomena or inelastic scatterings. It has been applied to diverse types of practical electronic devices such as carbon nanotubes, graphene nanoribbons, metallic nanowires, and molecular electronic devices. The quantum conductance phenomena for systems involving quantum point contacts and I‐V curves for a single molecule in contact with metal electrodes using the k‐point sampling method are described. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
DFT conformational studies of α‐maltotriose
Authors: Schnupf Udo , Willett Julious L. , Bosma Wayne B. , Momany Frank A. 
Published: December 2007

AbstractRecent DFT optimization studies on α‐maltose improved our understanding of the preferred conformations of α‐maltose. The present study extends these studies to α‐maltotriose with three α‐D‐glucopyranose residues linked by two α‐[1→4] bridges, denoted herein as DP‐3's. Combinations of gg, gt, and tg hydroxymethyl groups are included for both “c” and “r” hydroxyl rotamers. When the hydroxymethyl groups are for example, gg‐gg‐gg, and the hydroxyl groups are rotated from all clockwise, “c”, to all counterclockwise, “r”, the minimum energy positions of the bridging dihedral angles (ϕH and ψH) move from the region of conformational space of (−, −), relative to (0°, 0°), to a new position defined by (+, +). Further, it was found previously that the relative energies of α‐maltose gg‐gg‐c and “r” conformations were very close to one another; however, the DP‐3's relative energies between hydroxyl “c” or “r” rotamers differ by more than one kcal/mol, in favor of the “c” form, even though the lowest energy DP‐3 conformations have glycosidic dihedral angles similar to those found in the α‐maltose study. Preliminary solvation studies using COSMO, a dielectric solvation method, point to important solvent contributions that reverse the energy profiles, showing an energy preference for the “r” forms. Only structures in which the rings are in the chair conformation are presented here. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Electron localizability indicators ELI and ELIA: The case of highly correlated wavefunctions for the argon atom
Authors: Bezugly Viktor , Wielgus Pawel , Wagner Frank R. , Kohout Miroslav , Grin Yuri 
Published: December 2007

AbstractElectron localizability indicators based on the same‐spin electron pair density and the opposite‐spin electron pair density are studied for correlated wavefunctions of the argon atom. Different basis sets and reference spaces are used for the multireference configuration interaction method following the complete active space calculations aiming at the understanding of the effect of local electron correlation when approaching the exact wavefunction. The populations of the three atomic shells of Ar atom in real space are calculated for each case. © 2007 Wiley Periodicals, Inc. J Comput Chem 29: 1198–1207, 2008
Sonography of endometriosis in infrequent sites
Authors: Park Sung Bin , Kim Jeong Kon , Cho Kyoung‐Sik 
Published: December 2007

AbstractWe reviewed the sonographic features of endometriosis in infrequent sites, including the abdominal wall, appendix, perineum, and bladder. Familiarity with the clinical setting and the songraphic appearance of endometriosis in both frequent and infrequent sites can help facilitate prompt, accurate diagnosis and treatment. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2008
Analysis of the intracellular barriers encountered by nonviral gene carriers in a model of spatially controlled delivery to neurons
Authors: Bergen Jamie M. , Pun Suzie H. 
Published: December 2007

AbstractBackgroundNeuron‐specific, nonviral gene delivery vehicles are useful tools for the potential treatment of neurological disease and spinal cord injury. For minimally invasive, peripheral administration, gene carriers must efficiently mediate uptake at axon terminals, retrograde axonal transport, vesicular escape, and nuclear entry. The design of improved vehicles will benefit from an understanding of the barriers that limit nonviral delivery to neurons. Here, we demonstrate a detailed analysis of intracellular trafficking of both a lipid‐based and a polymer‐based delivery vehicle following site‐specific exposure to neuron‐like cells.MethodsSite‐specific exposure of gene carriers to soma or neurites of neuron‐like PC‐12 cells was accomplished using a microfluidic, compartmented culture chamber. Binding and internalization of vehicles at neurites and soma were quantified using an environmentally sensitive fluorescent marker. The intracellular transport of gene carriers was analyzed by time‐lapse particle tracking in live cells, and transfection efficiencies were measured using green fluorescent protein (GFP) as a reporter gene.ResultsWhile the lipid‐based carrier mediated measurable transfection when delivered to neuronal soma, neuritic delivery of this formulation failed to produce reporter gene expression due to limited internalization and transport. In contrast, the polymeric nanoparticles displayed active retrograde transport toward neuronal soma, but failed to produce measurable reporter gene expression.ConclusionsThese results highlight distinct intracellular barriers preventing efficient neuronal transfection by the nonviral carriers examined, and provide a basis for the rational improvement of existing nonviral systems. Copyright © 2007 John Wiley & Sons, Ltd.
Highly efficient gene transfer with degradable poly(ester amine) based on poly(ethylene glycol) diacrylate and polyethylenimine in vitro and in vivo
Authors: Park Mi Ran , Kim Hyon Woo , Hwang Chang Sun , Han Ki Ok , Choi Yun Jaie , Song Soo Chang , Cho Myung Haing , Cho Chong Su 
Published: December 2007

AbstractBackgroundPolyethylenimine (PEI) is toxic although it is one of the most successful and widely used gene delivery polymers with the aid of the proton sponge effect. Therefore, development of new novel gene delivery carriers having high efficiency with less toxicity is necessary.MethodsIn this study, a degradable poly(ester amine) carrier based on poly(ethylene glycol) diacrylate (PEGDA) and low molecular weight linear PEI was prepared. Furthermore, we compared the gene expression of the polymer/DNA complexes using two delivery methods: intravenous administration as an invasive method and aerosol as a non‐invasive method.ResultsThe synthesized polymer had a relatively small molecular weight (MW = 7980) with 25 h half‐life in vitro. The polymer/DNA complexes were formed at an N/P ratio of 9. The particle sizes and zeta‐potentials of the complexes were dependent on N/P ratio. Compared to PEI 25K, the newly synthesized polymer exhibited high transfection efficiency with low toxicity. Poly(ester amine)‐mediated gene expression in the lung and liver was higher than that of the conventional PEI carrier. Interestingly, non‐invasive aerosol delivery induced higher gene expression in all organs compared to intravenous method in an in vivo mice study. Such an expressed gene via a single aerosol administration in the lung and liver remained unchanged for 7 days.ConclusionsOur study demonstrates that poly(ester amine) may be applied as an useful gene carrier. Copyright © 2007 John Wiley & Sons, Ltd.
Inducing huntingtin inclusion formation in primary neuronal cell culture and in vivo by high‐capacity adenoviral vectors expressing truncated and full‐length huntingtin with polyglutamine expansion
Authors: Huang Bin , Schiefer Johannes , Sass Christian , Kosinski Christoph M. , Kochanek Stefan 
Published: December 2007

AbstractBackgroundHuntington's disease (HD) is an inherited autosomal dominant neurodegenerative disease caused by the expansion of a CAG trinucleotide repeat in exon 1 of the huntingtin (htt) gene. Vector‐mediated delivery of N‐terminal fragments of mutant htt has been used to study htt function in vitro and to establish HD models in rats. Due to the large size of the htt cDNA vector‐mediated delivery of full‐length htt has not been achieved so far.MethodsHigh‐capacity adenoviral (HC‐Ad) vectors were generated expressing mutant and wild‐type versions of N‐terminal truncated and full‐length htt either in vitro in primary neuronal cells or in the striatum of mice.ResultsIn vitro these vectors were used for transduction of primary neuronal cells isolated from E17 mouse embryos. Expression of mutant htt resulted in the formation of htt inclusions, a surrogate marker of the HD pathology. Kinetics of generation and localization of htt inclusions differed between truncated and full‐length htt carrying identical mutations. Following injection into the striatum vector‐mediated expression of mutant truncated htt led to prominent accumulation of htt inclusions in cell nuclei, while inclusions formed upon expression of mutant full‐length htt localized to the cytoplasm.ConclusionsThese results indicate that HC‐Ad vector‐mediated in vitro and in vivo delivery of truncated and full‐length mutant htt results in prominent inclusion formation in neuronal cells but in different cell compartments. These vectors will be useful tools for studying HD and may be used to generate large animal HD models. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of superoxide dismutase deficiency on zinc toxicity in Schizosaccharomyces pombe
Authors: Tarhan Cagatay , Pekmez Murat , Karaer Semian , Arda Nazli , Sarikaya Aysegul T. 
Published: December 2007

AbstractZinc is a metal which is a cofactor in many enzymes and a structural element in zinc finger motifs those are important in relation between DNA and regulator proteins. Little is known about uptake, distribution, toxicity and detoxification of zinc ions in cells. In this study, zinc toxicity and detoxification levels have been compared in wild type and Cu/Zn superoxide dismutase mutant (sod1Δ) cells of the fission yeast Schizosaccharomyces pombe. We evaluated the toxic levels of zinc, total zinc content, lipid peroxidation levels and catalase activities for both strains which were grown in medium containing different concentrations of zinc. sod1Δ mutant showed important growth retardation and has higher lipid peroxidation and catalase activities than wild type. Cu/Zn superoxide dismutase (SOD1) activity of wild type cells was markedly increased when they were treated with elevated levels of zinc. SOD1 mRNA level also significantly increased when the cells treated with higher concentrations of zinc. These results indicate that the mutant cells were more sensitive to zinc stress and seemed to have more oxidative intracellular environment than wild type cells. Our results support the idea that superoxide dismutase is an important factor for zinc detoxification in eukaryotes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Loading and in vitro Controlled Release of Indomethacin Using Amphiphilic Cholesteryl‐Bearing Carboxymethylcellulose Derivatives
Authors: Yang Liqun , Kuang Jianliang , Wang Jun , Li Zhiquan , Zhang Li‐Ming 
Published: December 2007

AbstractAmphiphilic CCMCs were synthesized under mild conditions and their chemical structures were characterized by FT‐IR and 1H NMR spectroscopy. Fluorescence analysis showed that CCMCs could self‐associate to form polymeric micelles in aqueous solution. IND was encapsulated during the formation of CCMC micelles and its in vitro release properties were investigated. The loading capacity was more than 50% and the loaded IND was slowly and steadily released into the medium over a period of 8 h. The CCMC micelles showed pH‐responsive behavior during the drug‐loading and release processes. CCMC is promising as a potential delivery system for the controlled release of IND with a pH‐responsive property.magnified image
Application of a multi‐channel zero‐resistance current amplifier for screening processes
Authors: Plagemann P. , Anton A. , Yezerska O. , Schneider M. , Schrems P. 
Published: December 2007

AbstractIn addition to being a very useful monitoring technique, electrochemical noise analysis is also particularly suitable for screening purposes. A multi‐channel zero‐resistance current amplifier was designed in order to be able to carry out multiple noise measurements simultaneously, thus allowing a greater number of tests to be performed in a given time. Electrochemical noise measurements were carried out on AA 2024 in NaCl solutions of different concentrations and in the presence of inhibitors to highlight the practical relevance of this analytical method. The results show that the noise data can be evaluated in a simple and clear way using the noise charge.
The factor time at the formation and development of the passive layer in the atmosphere
Authors: Bierwirth M. , Goellner J. , Heyn A. , Winkelmans M. 
Published: December 2007

AbstractPassive layers on high alloyed chromium nickel steels protect the metal from corrosion. The protective effect of the passive layer, however, does not immediately exist after the final surface treatment. Some time is necessary to form the protective layer. The exposure conditions are also decisive for the formation and further development of the passive layer besides the surface treatment. Samples of different chromium nickel steels are pickled and active passivated before they are exposed under laboratory conditions and in outdoor climates at different locations. The state of the corrosion resistance of the surface is determined with electrochemical noise measurements after different exposure times. The decreasing activity of the surface with an increasing exposure time indicates the further formation process of the protective qualities of the passive layer. An index which quantifies the state of the surface at the time of the measuring is calculated from the measured potential and potential noise signals. With these results, the development of the passive layer can be assessed and the corrosion resistance of the metal can then be estimated.
Electrochemical noise measurements on unalloyed steel in chloride‐containing alkaline environment
Authors: Eichler T. , Burkert A. , Beck M. 
Published: December 2007

AbstractThe investigations discussed in this paper aim to clarify whether electrochemical noise measurements (ENM) are capable for application in concrete and mortar, particularly with regard to pitting initiation in such environment. For these purposes, the results of several different test series are compared and discussed. Based on investigations on passivity and pitting corrosion in alkaline solutions with different chloride contents further results in cement paste, mortar and concrete are evaluated.
Synthesis and Study of CdS Nanoparticle‐Doped Poly(1,4‐dihexyloxybenzene)
Authors: Paul Gouri Sankar , Sarmah Pranjol Jyoti , Iyer Parameswar Krishnan , Agarwal Pratima 
Published: December 2007

AbstractA simple, economical and high yielding method to prepare poly(1,4‐dihexyloxybenzene), an alkylated derivative of poly(para‐phenylene) (PPP), is reported. We further prepared a composite of poly(1,4‐dihexyloxybenzene) and CdS nanoparticles and studied their structural, optical, stability and transport properties. It was observed that the conductivity of poly(1,4‐dihexyloxybenzene) increased by several orders of magnitude when doped with CdS nanoparticles. Similarly, CdS nanoparticle‐doped PPP showed higher thermal stability, when compared to the neat polymer. As these composites could be processed in the same way as organic polymers, they would find applications in many low‐cost optoelectronic devices.magnified image
Salt‐Induced Micelle Behavior of Poly(sodium acrylate)‐block‐Poly(N‐isopropylacrylamide) by ATRP
Authors: Jin Shuping , Liu Mingzhu , Chen Shilan , Gao Chunmei 
Published: December 2007

AbstractTemperature‐ and pH‐sensitive diblock copolymers PAANa75‐b‐PNIPAMm are prepared by a combination of reverse and normal ATRP in aqueous solution at room temperature. The block copolymer is also stimuli‐sensitive with respect to salt in the aqueous solution, and forms spherical star‐like micelles with a PNIPAM core and an expanded PAANa shell for PAANa75‐b‐PNIPAM76 as well as spherical crew‐out micelles with a PNIPAM core for PAANa75‐b‐PNIPAM5110, as indicated by a fluorescence probe technique and TEM. A three‐stage model mechanism of phase transition driven by small molecule salt is proposed.magnified image
Features, Questions and Future Challenges in Layered Silicates Clay Nanocomposites with Semicrystalline Polymer Matrices
Authors: Harrats Charef , Groeninckx Gabriel 
Published: December 2007

AbstractThe present features review article discusses the crystallisation of the polymer matrix when containing silicate layers. The accent is put on nylons (polyamides) and poly(ethylene oxide) as typical hydrophilic polymers and, poly(propylene) from the hydrophobic group. The effects of the clay, either intercalated or exfoliated, on the crystallisation behaviour of the matrix are highlighted. In addition, the crucial aspects of the semicrystalline morphology of the matrix in the presence of the clay platelets are also debated. The overall crystallisation rate is reported to slow down for most of the crystallisable polymer matrices on account of a retarding growth effect exerted by the clay platelets. As far as the location of the exfoliated clay platelets in the polymer matrix is concerned, they are assumed to be rejected from the crystalline phase in the interspherulitic space.magnified image