bluuebunny/crossref_metadata_2025_split huggingface dataset:
pFARs, Plasmids free of antibiotic resistance markers, display high‐level transgene expression in muscle, skin and tumour cells
Authors: Marie Corinne , Vandermeulen Gaëlle , Quiviger Mickaël , Richard Magali , Préat Véronique , Scherman Daniel 
Published: March 2010

AbstractBackgroundNonviral gene therapy requires a high yield and a low cost production of eukaryotic expression vectors that meet defined criteria such as biosafety and quality of pharmaceutical grade. To fulfil these objectives, we designed a novel antibiotic‐free selection system.MethodsThe proposed strategy relies on the suppression of a chromosomal amber mutation by a plasmid‐borne function. We first introduced a nonsense mutation into the essential Escherichia coli thyA gene, resulting in thymidine auxotrophy. The bacterial strain was optimized for the production of small and novel plasmids free of antibiotic resistance markers (pFARs) and encoding an amber suppressor t‐RNA. Finally, the potentiality of pFARs as eukaryotic expression vectors was assessed by monitoring luciferase activities after electrotransfer of LUC‐encoding plasmids into various tissues.ResultsThe introduction of pFARs into the optimized bacterial strain restored normal growth to the auxotrophic mutant and allowed an efficient production of monomeric supercoiled plasmids. The electrotransfer of LUC‐encoding pFAR into muscle led to high luciferase activities, demonstrating an efficient gene delivery. In transplanted tumours, transgene expression levels were superior after electrotransfer of the pFAR derivative compared to a plasmid carrying a kanamycin resistance gene. Finally, in skin, whereas luciferase activities decreased within 3 weeks after intradermal electrotransfer of a conventional expression vector, sustained luciferase expression was observed with the pFAR plasmid.ConclusionsThus, we have designed a novel strategy for the efficient production of biosafe plasmids and demonstrated their potentiality for nonviral gene delivery and high‐level transgene expression in several tissues. Copyright © 2010 John Wiley & Sons, Ltd.
Performance of HPLC/MS microchips in isocratic and gradient elution modes
Authors: Ehlert Steffen , Trojer Lukas , Vollmer Martin , van de Goor Tom , Tallarek Ulrich 
Published: March 2010

AbstractWe analyzed the chromatographic performance of particle‐packed, all‐polyimide high‐performance liquid chromatography/mass spectrometry (HPLC/MS) microchips in terms of their hydraulic permeabilities and separation efficiency under isocratic and gradient elution conditions. The separation channels of the chips (with ca 50 µm × 75 µm trapezoidal cross‐section and a length of 43 mm) were slurry packed with either 3.5 or 5 µm spherical porous C18‐silica particles. A custom‐built holder enveloped the chip during packing to prevent channel deformation and delamination from high pressures. It is shown that the packing conditions significantly impact the packing density of the HPLC/MS chips, which determines their performance in both, isocratic and gradient elution modes. Even with steep solvent gradients, peak shape and chromatographic resolution for the densely packed HPLC/MS chips are much improved. Our data show that the analytical power of the HPLC/MS chip is limited by the quality of the chromatographic separation. Copyright © 2010 John Wiley & Sons, Ltd.
Geochemical evidence (C, N and Pb isotopes) of recent anthropogenic impact in south‐central Chile from two environmentally distinct lake sediment records
Authors: Fagel Nathalie , Bertrand Sebastien , Mattielli Nadine , Gilson Delphine , Chirinos Luis , Lepoint Gilles , Urrutia Roberto 
Published: March 2010

AbstractIn this paper, we compare the elemental and isotopic (C, N, Pb) geochemistry of lake sediments from two contrasted environments in south‐central Chile. The first lake, Laguna Chica de San Pedro (LCSP), is situated in the urbanised area of the Biobio Region (36°S). The second lake, Lago Puyehue (40° S), is located 400 km to the southeast of LCSP and within an Andean national park. Our aim is to identify environmental impacts associated with increasing industrial activities and land degradation during the last 150 a. In LCSP, shifts in C/N atomic ratios, δ13C and δ15N from 1915–1937 to the late 1980s are attributed to successive land degradation episodes in the lake watershed. Based on a Pb isotopic mixing model, we estimate that up to 20% of lead in LCSP sediments is supplied from urban atmospheric pollution. By contrast, human impact in the watershed of Lago Puyehue is very limited. We observe no change in organic geochemistry during the last 150 a and lead contamination remains lower than 5%, even during the last decades. Although contamination levels are much higher in LCSP than in Lago Puyehue, a peak in anthropogenic Pb is recorded during the same period (1974–1976) at both sites. This maximum contamination level is consistent with increased industrial activity in the vicinity of Concepción. Copyright © 2010 John Wiley & Sons, Ltd.
Purification and biochemical characterisation of a novel glutamate decarboxylase from rice bran
Authors: Wang Li , Xu Dong Xia , Lv Ying Guo , Zhang Hui 
Published: March 2010

AbstractBACKGROUND: Glutamate decarboxylase (GAD) is a useful enzyme whose main function is to catalyse the irreversible α‐decarboxylation of L‐glutamate to produce γ‐aminobutyric acid. The cheap and abundant rice‐processing by‐product rice bran contains a high amount of GAD, the purification and characterisation of which have not yet been reported. In this study, research on rice bran GAD was initiated.RESULTS: Rice bran GAD was purified to homogeneity via a combined purification protocol of ammonium sulfate fractionation, ion exchange chromatography and two gel filtrations, with a purification fold of 128.6 and an activity recovery of 21.3%. The enzyme was active at pH 5.5 and 40 °C and retained 80% of its original activity in the pH range 5–9 and the temperature range 30–50 °C. GAD activity was significantly enhanced in the presence of Ca2+ but strongly inhibited by Ag+, Hg2+, sodium dodecyl sulfate and CH3COOH. Kinetic determination of the apparent Km for L‐glutamate and pyridoxal 5′‐phosphate gave values of 27.4 mmol L−1 and 1.16 µmol L−1 respectively.CONCLUSION: Considering that rice bran is cheap and commercially available and that rice bran GAD is relatively stable, the development of cost‐effective rice bran GAD‐related functional foods would seem to be feasible. Copyright © 2010 Society of Chemical Industry
Cholesterol and lipid oxidation in raw and pan‐fried minced beef stored under aerobic packaging
Authors: Ferioli Federico , Dutta Paresh C , Caboni Maria F 
Published: March 2010

AbstractBACKGROUND: The type of packaging atmosphere has been reported as a technological factor that consistently affects the quality of lipid fraction in meat. Oxidation of cholesterol and lipids was evaluated before and after pan frying in commercial refrigerated minced beef stored under aerobic atmosphere for 1 and 8 days.RESULTS: In raw beef, cholesterol and lipid oxidation developed at a slow rate. Cholesterol oxidation products (COPs) did not significantly vary (∼8 µg COPs g−1 of fat) over 8 days, while in the same period thiobarbituric acid reactive substances (TBARS) less than doubled (from 0.7 to 1.2 malondialdehyde equivalents kg−1 of muscle). Pan frying did not influence the oxidative degree in the fresh product but consistently catalyzed cholesterol oxidation in stored beef. A significant increase was assessed in beef at the end of storage: from 8.6 to 30.0 µg COPs g−1 of fat in raw and cooked beef, respectively.CONCLUSION: Aerobic packaging did not appear as a pro‐oxidant factor in fresh minced beef with a good oxidative quality during a short period of refrigerated storage. Copyright © 2010 Society of Chemical Industry
Biochemical, biological and histological evaluation of some culinary and medicinal herbs grown under greenhouse and field conditions
Authors: Yi Weiguang , Wetzstein Hazel Y 
Published: March 2010

AbstractBACKGROUND: Increasing evidence supports the potential health benefits of herbal extracts displaying antioxidant, anti‐inflammatory and antitumour activities. Environment can have a pronounced effect on phenolic content and antioxidant capacity. The objectives of this study were to evaluate the total phenolic contents and antioxidant capacities of five different herbs grown under greenhouse and field conditions and to assess their potential anti‐inflammatory effects.RESULTS: High total polyphenolic (TPP) content (measured by the Folin‐Ciocalteu reagent method) and high Trolox equivalent antioxidant capacity (TEAC) were observed in all herbs evaluated. Leaves from thyme, sage, spearmint and peppermint grown in the greenhouse showed significantly higher TPP content and TEAC than those grown under field conditions, with a threefold difference being observed in peppermint. Rosemary, spearmint and peppermint extracts showed stronger inhibition of cyclooxygenase COX‐2 than of COX‐1.CONCLUSION: The results show that producing herbs under greenhouse conditions can improve their biological activities by increasing TPP contents and antioxidant capacities. The selective inhibition of COX‐2 activity by rosemary, spearmint and peppermint suggests that they may be useful as anti‐inflammatory agents with fewer side effects than regular non‐steroidal drugs. Copyright © 2010 Society of Chemical Industry
Influence of the Doping Level on the Interactions between Poly(3,4‐ethylenedioxythiophene) and Plasmid DNA
Authors: Teixeira‐Dias Bruno , Zanuy David , del Valle Luis J. , Estrany Francesc , Armelin Elaine , Alemán Carlos 
Published: March 2010

AbstractThe influence of the doping level in the formation of specific interactions between plasmid DNA and PEDOT is investigated using experimental assays and theoretical calculations. Electrochemical methods are used to prepare polymer samples with oxidation degrees ranging from 0.14 to 1.05 positive charges per repeating unit. A combination of experimental and theoretical results are used to propose a mechanism for the formation of DNA/conducting polymer complexes, which consists of the initial stabilization of the adducts through non‐specific interactions followed by small structural re‐arrangements that allow to be established specific hydrogen bonds involving the polar groups of the conducting polymer and selected DNA bases.magnified image
Degradation of Poly(methyl methacrylate) Model Compounds Under Extreme Environmental Conditions
Authors: Bennet Francesca , Hart‐Smith Gene , Gruendling Till , Davis Thomas P. , Barker Philip J. , Barner‐Kowollik Christopher 
Published: March 2010

AbstractThere is a significant knowledge gap in the degradation of poly(methyl methacrylate) (pMMA) under conditions experienced by surface coatings in the harsh Australian environment. In the current study pMMA model compounds were exposed to 95 °C temperatures and high UV radiation (1 kW · m−2), separately as well as in combination. Contrary to the findings of previous studies, degradation proceeds in these conditions via a non‐radical cyclic mechanism. The mechanism was further confirmed by synthesis and degradation of ethylene‐oxide‐terminated pMMA, an intermediate product in the cycle. Electrospray ionisation mass spectrometry analysis of thermally degraded samples after 155 weeks shows degradation consistent with the proposed cycle in vinyl‐terminated pMMA, while saturated pMMA was shown to be stable after the same period. Saturation delayed the UV‐induced degradation, yet these compounds still displayed some slight degradation after 52 weeks, confirming the terminal vinyl bond in pMMA as a weak point. Combined UV and thermal radiation after 56 weeks showed degradation of both pMMA samples, with the vinyl‐terminated sample also exhibiting crosslinking. The combination of thermal and UV radiation also caused acceleration of degradation, shown by a comparison of the polymer samples after ≈60 weeks.magnified image
State of Order of the Crosslinker in Main‐Chain Liquid Crystalline Elastomers
Authors: Zander Frank , Finkelmann Heino 
Published: March 2010

AbstractRigid anisotropic crosslinkers have been shown to decrease the nematic order and the transition temperatures of main‐chain liquid crystalline elastomers (MCLCEs). In order to look into this phenomenon, the state of order of an anisotropic crosslinker in an MCLCE was investigated separately from that of the matrix. For this purpose, multifunctional perylene derivatives were synthesized and used as a crosslinker and as a reference mesogen probe. Their states of order were measured by their dichroism, and were compared to that of the MCLCE matrix. A systematically lower degree of order was observed for the crosslinker in comparison to the matrix, both when attached to and dissolved in the network.magnified image
Polyamide‐12/Functionalized Carbon Nanofiber Composites: Evaluation of Thermal and Mechanical Properties
Authors: Chávez‐Medellín Ricardo , Prado Luis A. Sanchez de Almeida , Schulte Karl 
Published: March 2010

AbstractThis work aims at improving the interfacial bonding between polyamide‐12 and CNFs. CNFs were oxidized and dispersed in polyamide‐12 giving rise to polymer nanocomposites. The oxidation caused an increase in the specific surface area and structural defects of the fibers, as indicated by surface area and Fourier‐transform Raman spectroscopy. The nanocomposites exhibited improved thermal and thermo‐oxidative stabilities. The oxidized nanofibers had marginal effect on the crystallinity and crystallization of the polyamide‐12. An over‐proportional enhancement of stiffness due to the fibers could be achieved. In spite of these improvements the fiber/polymer adhesion should be further improved.magnified image
Ensemble Rule‐Based Classification of Substrates of the Human ABC‐Transporter ABCB1 Using Simple Physicochemical Descriptors
Authors: Demel Michael A. , Kraemer Oliver , Ettmayer Peter , Haaksma Eric , Ecker Gerhard F. 
Published: March 2010

AbstractWithin the last decades, the detailed knowledge on the impact of membrane bound drug efflux transporters of the ATP binding cassette (ABC) protein family on the pharmacological profile of drugs has enormously increased. Especially, ABCB1 (P‐glycoprotein, P‐gp, MDR1) has attracted particular interest in medicinal chemistry, since it determines the clinical efficacy, side effects and toxicity risks of drug candidates. Based on this, the development of in silico models that provide rapid and cost‐effective screening tools for the classification of substrates and nonsubstrates of ABCB1 is an urgent need in contemporary ADMET profiling. A characteristic hallmark feature of this transporter is its polyspecific ligand recognition pattern. In this study we describe a method for classifying ABCB1 ligands in terms of simple, conjunctive rules (RuleFit) based on interpretable ADMET features. The retrieved results showed that models based on large, very diverse data sets gave better classification performance than models based on smaller, more homogenous training sets. The best model achieved gave a correct classification rate of 0.90 for an external validation set. Furthermore, from the interpretation of the best performing model it could be concluded that in comparison to nonsubstrates ABCB1 substrates generally show a higher number of hydrogen‐bond acceptors, are more flexible and exhibit higher logPvalues.
Quantitative Prediction of Regioselectivity Toward Cytochrome P450/3A4 Using Machine Learning Approaches
Authors: Hasegawa Kiyoshi , Koyama Michio , Funatsu Kimito 
Published: March 2010

AbstractIn the drug discovery process, it is important to know the properties of both drug candidates and their metabolites. Fast and precise prediction of metabolites is essential. However, it has been difficult to predict metabolites because of the complexity of the mechanism of cytochrome P450/3A4 (CYP 3A4), which is the main metabolite enzyme of drugs. In this study, we focus on the regioselectivity of CYP 3A4, i.e., the selectivity of metabolic sites. We have developed a model to predict the regioselectivity of drug candidates by using machine learning (ML) approaches.
Linearly tapered slotline antenna array for quasi‐optical molecular spectroscopy
Authors: Lukes Zbynek , Lacik Jaroslav , Raida Zbynek 
Published: March 2010

AbstractIn this article, a novel design of a millimeter‐wave antenna array consisting of linearly tapered slotline antenna elements is presented. The antenna array was designed for the frequency range from 50 to 600 GHz. A numerical model of the antenna array was developed in CST microwave studio. To optimize the antenna model, a novel real‐coded genetic algorithm was proposed. The optimized antenna was fabricated from a low‐loss dielectric substrate ARLON CuClad 217, and its parameters were experimentally verified. The antenna was designed for quasi‐optical terahertz spectroscopy applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1043–1046, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25110
Festkörperchemie 2009
Authors: Höppe Henning , Indris Sylvio , Schmedt auf der Günne Jörn 
Published: March 2010

AbstractSpektroskopie und Chemie der Festkörper — wie ein Stein mit vielen Facetten: intelligente Synthesen, die mit den Aggregatzuständen flüssig, gasförmig oder fest spielen, anspruchsvolle Strukturanalytik, Dynamik und Reaktionskinetik, Theorie der chemischen Bindung, reine Grundlagenforschung und der von Gesellschaft und Politik geforderte Transfer in die Anwendung.
Physikalische Chemie 2009: Zellen im Mikrochip
Authors: Kuhn Phillip , Dittrich Petra S. 
Published: March 2010

AbstractMit mikrofluidischen Plattformen lassen sich Veränderungen an einzelnen Zellen durch externe Einflüsse oder Zell‐Zell‐Kommunikation untersuchen. Das gewonnene Wissen wird nicht nur unser Verständnis für biologische Abläufe in lebenden Organismen erweitern, sondern kann auch helfen, Krankheiten besser zu verstehen und Medikamente zu entwickeln.
Chemiedidaktik 2009
Authors: Becker Hans‐Jürgen , Stäudel Lutz 
Published: March 2010

AbstractDie Chemiedidaktik belebt die Diskussion um Differenzierung im Unterricht zurzeit neu: Erkenntnisse werden aktualisiert, variiert und unter diagnostischer Perspektive problematisiert und reflektiert. Diese Diskussion liefert Lösungen für grundlegende Probleme von Chemieunterricht.
Optimization of magnetosonoporation for stem cell labeling
Authors: Xie Daohai , Qiu Bensheng , Walczak Piotr , Li Xubin , Ruiz‐Cabello Jesus , Minoshima Satoshi , Bulte Jeff W. M. , Yang Xiaoming 
Published: March 2010

AbstractRecent advances in magnetic cell labeling have taken place with the development of a magnetosonoporation (MSP) technique. The aim of this study was to optimize the MSP protocol in order to achieve high cell viability and intracellular uptake of MR contrast agents. First, we determined the sub‐optimal MSP parameters by evaluating the viabilities of C17.2 neural stem cells without Feridex using various MSP intensities ranging from 0.1 to 1 w/cm2, duty cycles at 20%, 50% or 100%, and exposure times from 1–15 min. The sub‐optimized MSP parameters with cell viabilities greater than 90% were further optimized by evaluating both cell viability and intracellular iron uptake when Feridex was used. We then used the optimized MSP parameters to determinate the optimal concentration of Feridex for magnetic cell labeling. Subsequently, we validated the feasibility of using MRI to track the migration of neural stem cells from the transplanted sites to glioma masses in four mouse brains when the cells had been labeled with Feridex using the optimized MSP protocol. The MRI findings were confirmed by histological correlations. In vitro experiments demonstrated that the optimal MSP protocol was achieved at 20% duty cycle, 0.3 w/cm2 ultrasound intensity, 5‐min exposure time and 1mg/mL Feridex. This study demonstrated that the optimized MSP cell labeling technique can achieve both high cell viability and intracellular uptake of MR contrast agents, and has the potential to be a useful cell labeling technique to facilitate future clinical translation of MRI‐integrated cell therapy. Copyright © 2010 John Wiley & Sons, Ltd.
The generalized minimum edge‐biconnected network problem: Efficient neighborhood structures for variable neighborhood search
Authors: Hu Bin , Leitner Markus , Raidl Günther R. 
Published: March 2010

AbstractWe consider the generalized minimum edge‐biconnected network problem where the nodes of a graph are partitioned into clusters and exactly one node from each cluster is required to be connected in an edge‐biconnected way. Instances of this problem appear, for example, in the design of survivable backbone networks. We present different variants of a variable neighborhood search approach that utilize different types of neighborhood structures, each of them addressing particular properties as spanned nodes and/or the edges between them. For the more complex neighborhood structures, we apply efficient techniques—such as a graph reduction—to essentially speed up the search process. For comparison purposes, we use a mixed integer linear programming formulation based on multi‐commodity flows to solve smaller instances of this problem to proven optimality. Experiments on such instances indicate that the variable neighborhood search is also able to identify optimal solutions in the majority of test runs, but within substantially less time. Tests on larger Euclidean and random instances with up to 1,280 nodes, which could not be solved to optimality by mixed integer programming, further document the efficiency of the variable neighborhood search. In particular, all proposed neighborhood structures are shown to contribute significantly to the search process. © 2010 Wiley Periodicals, Inc. NETWORKS, 2010
SGBEM with Lagrange multipliers applied to elastic domain decomposition problems with curved interfaces using non‐matching meshes
Authors: Vodička R. , Mantič V. , París F. 
Published: March 2010

AbstractAn original approach to the solution of linear elastic domain decomposition problems by the symmetric Galerkin boundary element method is developed. The approach is based on searching for the saddle‐point of a new potential energy functional with Lagrange multipliers. The interfaces can be either straight or curved, open or closed. The two coupling conditions, equilibrium and compatibility, along an interface are fulfilled in a weak sense by means of Lagrange multipliers (interface displacements and tractions), which enables non‐matching meshes to be used at both sides of interfaces between subdomains. The accuracy and robustness of the method is tested by several numerical examples, where the numerical results are compared with the analytical solution of the solved problems, and the convergence rates of two error norms are evaluated for h‐refinements of matching and non‐matching boundary element meshes. Copyright © 2010 John Wiley & Sons, Ltd.