bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retroviral vector production under serum deprivation: The role of lipids
Authors: Rodrigues A.F. , Carmo M. , Alves P.M. , Coroadinha A.S. 
Published: August 2009

AbstractThe use of retroviral vectors for gene therapy applications demands high titer preparations and stringent quality standards. However, the manufacturing of these vectors still represents a highly challenging task due to the low productivity of the cell lines and reduced stability of the vector infectivity, particularly under serum‐free conditions. With the objective of understanding the major limitations of retroviral vector production under serum deprivation, a thorough study of viral production kinetics, vector characterization and cell growth and metabolic behavior was conducted, for 293 FLEX 18 and Te Fly Ga 18 producer cell lines using different serum concentrations. The reduction of serum supplementation in the culture medium resulted in pronounced decreases in cell productivity of infectious vector, up to ninefold in 293 FLEX 18 cells and sevenfold in Te Fly Ga 18 cells. Total particles productivity was maintained, as assessed by measuring viral RNA; therefore, the decrease in infectious vector production could be attributed to higher defective particles output. The absence of the serum lipid fraction was found to be the major cause for this decrease in cell viral productivity. The use of delipidated serum confirmed the requirement of serum lipids, particularly cholesterol, as its supplementation not only allowed the total recovery of viral titers as well as additional production increments in both cell lines when comparing with the standard 10% (v/v) FBS supplementation. This work identified lower production ratios of infectious particles/total particles as the main restraint of retroviral vector production under serum deprivation; this is of the utmost importance concerning the clinical efficacy of the viral preparations. Lipids were confirmed as the key serum component correlated with the production of infective retroviral vectors and this knowledge can be used to efficiently design medium supplementation strategies for serum‐free production. Biotechnol. Bioeng. 2009; 104: 1171–1181. © 2009 Wiley Periodicals, Inc.
Evaluation of Optimization Metrics for Continuous Fermentation of Plasmid DNA
Authors: Kelly W. J. , Balguri M. , Asoor A. B. , Piccini J. R. , Muske K. R. 
Published: August 2009

AbstractAn evaluation of cumulative productivity metrics for optimizing the continuous fermentation of plasmid DNA (pDNA) is carried out in this work. DNA plasmids provide a good illustrative example for comparison because of the plasmid instability issues associated with their production. However, the analysis presented in this work can also be applied to other intracellular bioproduct continuous fermentation systems. The productivity metrics considered are cumulative product mass per time, profit, and cost objective functions. These metrics are used to determine the optimal continuous fermentation run time at a given dilution rate, during the dynamic period associated with switching from batch to continuous fermentation. The results of this study indicate that different optimum continuous fermentation run times are predicted based upon the choice of the continuous fermentation operating conditions and optimization metric. In particular, the dilution rate must be larger than the inverse of a characteristic time, that is a function of the initial batch operating and plasmid stability times before continuous operation becomes optimal. Provided that this condition is met, different optimal continuous operation run times are obtained depending on the cumulative productivity metric, or operating objective, that is employed.
On the Electronic Impact of Abnormal C4‐Bonding in N‐Heterocyclic Carbene Complexes
Authors: Heckenroth Marion , Neels Antonia , Garnier Michael G. , Aebi Philipp , Ehlers Andreas W. , Albrecht Martin 
Published: August 2009

AbstractSterically similar palladium dicarbene complexes have been synthesized that comprise permethylated dicarbene ligands which bind the metal center either in a normal coordination mode via C2 or abnormally via C4. Due to the strong structural analogy of the complexes, differences in reactivity patterns may be attributed to the distinct electronic impact of normal versus abnormal carbene bonding, while stereoelectronic effects are negligible. Unique reactivity patterns have been identified for the abnormal carbene complexes, specifically upon reaction with Lewis acids and in oxidative addition‐reductive elimination sequences. These reactivities as well as analytical investigations using X‐ray diffraction and X‐ray photoelectron spectroscopy indicate that the C4 bonding mode increases the electron density at the metal center substantially, classifying such C4‐bound carbene ligands amongst the most basic neutral donors known thus far. A direct application of this enhanced electron density at the metal center is demonstrated by the catalytic H2 activation with abnormal carbene complexes under mild conditions, leading to a catalytic process for the hydrogenation of olefins.
RelB/p50 regulates CCL19 production, but fails to promote human DC maturation
Authors: Gasparini Chiara , Foxwell Brian M. J. , Feldmann Marc 
Published: August 2009

AbstractDC, when fully matured are the APC best able to activate naïve T cells. Recently, we demonstrated using adenoviruses overexpressing IκBα and proteosome inhibitors that NF‐κB is involved in DC activation, but the role of the individual subunits is still not clear. We investigated the role of the NF‐κB subunits RelB and p50 in human DC activation using adenoviral vectors expressing RelB or p50. Nuclear RelB, in the form of RelB/p50, was active only in DC infected with both viruses, this induced the production of the soluble homeostatic chemokine CCL19, but not other homeostatic chemokines, particularly in LPS‐matured DC. However, RelB/p50 did not affect the expression of costimulatory and antigen‐presenting molecules, and increased the allogeneic mixed lymphocyte reaction only in LPS‐matured DC. This enhanced mixed lymphocyte reaction is most likely due to enhanced CCL19 production, which sustains the interaction between mature DC and naïve T cells. In conclusion, we demonstrated that RelB/p50 was active only in DC expressing both RelB and p50, and induced CCL19 production, but not DC maturation.
Si94– Anions in Solution – Structures of the Solvates Rb4Si9·4.75NH3 and [Rb(18‐crown‐6)]Rb3Si9·4NH3, and Chemical Bonding in Si94–
Authors: Joseph Stefanie , Suchentrunk Christof , Kraus Florian , Korber Nikolaus 
Published: August 2009

AbstractDissolving the ternary material K6Rb6Si17 together with chelating ligands such as 18‐crown‐6 (1,4,7,10,13,16‐hexaoxacyclooctadecane), dibenzo‐18‐crown‐6 (2,3,11,12‐dibenzo‐1,4,7,10,13,16‐hexaoxacyclooctadecane) and [2.2.2]cryptand(4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane)in liquid ammonia yields the solvates Rb4Si9·4.75NH3 and [Rb(18‐crown‐6)]Rb3Si9·4NH3. Single‐crystal X‐ray diffraction analysis reveals the presence of Si94– anions, the existence of which in solution has been a matter of discussion until now. In both compounds, the Si94– cages display slightly distorted monocapped square‐antiprismatic shapes. Additionally, quantum chemical calculations, NBO analysis and ELF (electron localisation function) considerations have been made to gain a deeper insight into the chemical bonding of this Zintl anion. The ELF analysis shows that, whereas the Wade–Mingos–Williams rules obviously apply for the prediction of the molecular shape of the anions, no evidence for three‐centre two‐electron bonding can be found. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Peptization–Hydrothermal Method as a Surfactant‐Free Process toward Nanorod‐Like Anatase TiO2Nanocrystals
Authors: Li Shuang , Li Yaogang , Wang Hongzhi , Fan Wugang , Zhang Qinghong 
Published: August 2009

AbstractThe transparent TiO2sol contained of anatase crystallites was prepared by peptization of anatase TiO2precipitates. With the hydrothermal treatment of TiO2sol at 150 °C, the dispersible and nanorod‐like TiO2nanocrystals were formed by an oriented attachment mechanism. After further hydrothermal treatment of the mixture of nanorod‐like TiO2nanocrystals and the original sol, branched and nanoring‐like nanostructures in the anatase phase were obtained. The as‐prepared TiO2nanocrystals were characterized by X‐ray diffraction, FT‐Raman spectrometry, UV/Vis absorption spectrometry, and transmission electron microscopy (TEM). TEM results indicated that TiO2nanocrystals were nanorod‐like, and more complex microstructures such as the ring‐like and branched TiO2nanostructures with diameters less than 10 nm were formed especially in the two‐step hydrothermal treatment. The adsorption of ruthenium dye (N719) over the nanocrystals with different microstructures was investigated. The adsorption results showed the nanorod‐like anatase TiO2nanocrystals had a high capacity for the ruthenium dye adsorption. The powders were used as electrodes of dye‐sensitized solar cells and showed a conversion efficiency of 5.75 % under 1 sun illumination unit of simulated sunlight. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Double‐Layer Nanogold and Poly(amidoamine) Dendrimer‐ Functionalized PVC Membrane Electrode for Enhanced Electrochemical Immunoassay of Total Prostate Specific Antigen
Authors: Wang Xiu‐Ling , Tao Guan‐Hong , Meng Yuan‐Hua 
Published: August 2009

AbstractA simple and portable electrochemical immunosensor for the detection of total prostate specific antigen (t‐PSA) in human serum was developed using a double‐layer nanogold particles and dendrimer‐functionalized polyvinyl chloride (PVC) membrane as immunosensing interface. To fabricate such a multifunctional PVC electrode, an o‐phenylenediamine‐doped PVC membrane was initially constructed, then nanogold particles and poly(amidoamine) G4‐dendrimer with a sandwich‐type format were assembled onto the PVC membrane surface, and then t‐PSA antibodies (anti‐PSA) were adsorbed on the nanogold surface. The detection principle of the immunosensor is based on the change in the electric potential before and after the antigen‐antibody interaction. The experimental conditions and the factors influencing the performance of the immunosensor were investigated. Under optimal conditions, the proposed immunosensor exhibits good electrochemical behavior in the dynamic range of 0.5–18 ng/mL relative to t‐PSA concentration with a relative low detection limit of 0.1 ng/mL (S/N=3). The precision, reproducibility, and stability of the immunosensor are acceptable. In addition, 43 serum specimens were assayed by the as‐prepared immunosensor, and consistent results were obtained in comparison with those obtained by the standard enzyme‐linked immunosorbent assay (ELISA). Compared with the conventional ELISAs, the developed immunoassay system was simple and rapid without labeling and separation steps. Importantly, the immobilization and detection methodologies could be extended for the immobilization and detection of other biomarkers.
Peroxidase‐Like Layered Double Hydroxide Nanoflakes for Electrocatalytic Reduction of H2O2
Authors: Wang Yinling , Chen Shuihong , Ni Fang , Gao Feng , Li Maoguo 
Published: August 2009

AbstractPeroxidase‐like layered double hydroxide (LDH) nanoflakes were synthesized directly and facilely by a one‐pot chemical method, hydrothermal treatment. The as‐prepared LDHs were characterized by transmission electron microscopy, scanning electron microscopy, X‐ray diffraction, Fourier transform IR, and cyclic voltammetry. The functionalized LDHs immobilized on the glassy carbon electrode exhibited a well‐defined pair of redox peaks, excellent electrocatalytic activity toward the reduction of hydrogen peroxide without inhibition of dissolved oxygen and a higher affinity for H2O2, just like the peroxidase. The low apparent Michaelis–Menten constant was only 242 μM. The electrochemical response to H2O2 shows a linear range of 12–254 μM with the calculated detection limit of 2.3 μM at a signal‐to‐noise ratio of 3. Furthermore, compared with most metal hexacyanoferrates, the peroxidase‐like LDHs are very stable in neutral and alkaline solution. The electrochemical and electrocatalytic behavior of the functionalized LDHs indicate that they may be useful to explore man‐made mimics of enzyme in electrochemical biosensors.
Structured Nucleic Acid Probes for Electrochemical Devices
Authors: Miranda‐Castro Rebeca , de‐los‐Santos‐Álvarez Noemí , Lobo‐Castañón María Jesús , Miranda‐Ordieres Arturo J. , Tuñón‐Blanco Paulino 
Published: August 2009

AbstractThe use of nucleic acid with a specific sequence and a highly ordered secondary structure such as hairpins, quadruplexes and pseudoknots as biological recognition elements and switches in biosensors is rapidly increasing because of their improved features (e.g. selectivity) when compared with the traditional linear probes. Owing to the novelty, a critical outlook of their characteristics and a compilation of the latest advances are lacking. This article describes the potential of those nucleic acids probes whose molecular recognition ability relies on a conformational change (e.g. folding/unfolding mechanism) in electrochemical sensing. It provides an overview of the toolbox of assays using these probes for genosensors and aptasensors, highlighting its performance characteristics and the prospects and challenges for biosensor design.
On‐column labeling technique and chiral ligand‐exchange CE with zinc(II)‐L‐arginine complex as a chiral selector for assay of dansylated D,L‐amino acids
Authors: Qi Li , Yang Gengliang 
Published: August 2009

AbstractA novel on‐column labeling method of amino acid (AA) enantiomers by using dansyl chloride (Dns‐Cl) has been explored combined with chiral ligand‐exchange CE (CLE‐CE) technique and UV detection. Efficient labeling was achieved by sequential injection of buffer, Dns‐Cl, AA enantiomers, Dns‐Cl and buffer at 0.2 psi for 10.0, 3.0, 24.0, 3.0, and 10.0 s, respectively. After injection, the sandwich sections were allowed to react at room temperature for 35.0 min. With this procedure, successful on‐column labeling and CLE‐CE separation of 17 pairs AA enantiomers have been achieved with a buffer of 100.0 mM boric acid, 5.0 mM ammonium acetate, 3.0 mM ZnSO4 and 6.0 mM L‐Arg at pH 8.4, giving nine pairs fully enantioresolved with resolution in between 2.0 and 5.1. CLE‐CE of some individual and mixed pairs was also demonstrated, much the same as using pre‐column labeling. As validated by both artificially prepared solutions and serum samples, this new method was shown to be applicable to the quantitative analysis, with a linear range between 14.0 μM and 3.7 mM, correlation coefficient above 0.99 and recovery in between 90.4% and 111.7%. It was also demonstrated that the migration time‐temperature based curve allows for temperature determination in CE by using this new method.
Enantiomeric separation of chiral dipeptides by CE‐ESI‐MS employing a partial filling technique with chiral crown ether
Authors: Xia Shifei , Zhang Lan , Lu Minghua , Qiu Bin , Chi Yuwu , Chen Guonan 
Published: August 2009

AbstractEnantiomer of chiral dipeptides were separated by CE‐ESI‐MS in a bare fused‐silica capillary using (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid (18C6H4) as the chiral selector. As 18C6H4 is a kind of nonvolatile chiral selector, in order to prevent from 18C6H4 into the ion‐source of CE‐ESI‐MS, a partial filling technique was employed in this study. Some dipeptides with one chiral center or two chiral centers, such as DL‐Leu‐DL‐Leu, D‐Ala‐D‐Ala and L‐Ala‐L‐Ala, Gly‐D‐Phe and Gly‐L‐Phe were used to evaluate this CE‐ESI‐MS system. Optimized conditions were achivevd with 2.0 mol/L acetic acid (pH 2.15) as the running electrolyte, 5 mM 18C6H4 in 3.0 mol/L acetic acid (pH 2.00) was injected hydrodynamically (50 mbar for 960 s) before sample injection. In total 7.5 mM acetic acid in 80% v/v methanol–water was used as the sheath liquid, and 20 kV applied voltage was used. Under the optimum conditions, these dipeptides were separated and detected. LODs (defined as S/N=3) of this method were 0.20, 0.10, 0.05 and 0.10 μmol/L for D‐Ala‐D‐Ala, L‐Ala‐L‐Ala, DL‐Leu‐DL‐Leu, Gly‐L‐Phe and Gly‐D‐Phe, respectively. The RSDs (n=7) of the method were 0.68–2.08% for migration times and 2.32–5.24% for peak areas. The proposed method was also successfully applied to the enantioselective analysis of these dipeptides in the spiked serum samples with satisfactory results.
Enantioseparation of amino acids, α‐hydroxy acids, and dipeptides by ligand‐exchange CEC using silica‐based chiral stationary phases
Authors: Pittler Elfriede , Grawatsch Nina , Paul Dörte , Gübitz Gerald , Schmid Martin G. 
Published: August 2009

AbstractThis work deals with the application of silica‐based ligand‐exchange chiral stationary phases (CSPs) for the enantioseparation of underivatised amino acids, α‐hydroxy acids, and dipeptides with packed CEC. Two different possibilities of preparing silica‐based CSPs are presented. One phase contains L‐4‐hydroxyproline chemically bonded via a spacer to 3 μm silica material. The other approach makes use of N‐decyl‐L‐4‐hydroxyproline dynamically coated on a reversed‐phase packed capillary. Dynamical coating of reversed‐phase material represents a simple alternative to prepare CSP. A comparison of the chemically bonded phase with the dynamically coated CSP by means of resolution of complex‐forming analytes is presented. The chemically bonded phase was found to be superior to the dynamically coated phase in terms of resolution of amino acids and dipeptides. However, the dynamically coated CSP was found to be especially suitable for the separation of α‐hydroxy acids. Both techniques are applicable for enantiomer purity tests.
Adsorption of trypsin on commercial silica gel
Authors: Gómez José M. , Romero Ma. Dolores , Hodaifa Gassan , de la Parra Elena 
Published: August 2009

AbstractThe immobilization of trypsin onto various commercial silica gels was studied. Silica gels were used directly and characterized by mercuric porosimetry. Agitation rates (100–740 rpm) and particles size (35–75 to 250–500 μm) of silica gels did not affect the trypsin immobilization capacity. The pore size (3 to 15 nm) is a limiting factor of the trypsin adsorption onto the mesopores structure of silica gels. The adsorption of trypsin was determined as a function of their initial concentration and multilayer formed at high trypsin concentration.
Optimal seismic design of moment‐resisting steel frames with hysteretic passive devices
Authors: Apostolakis G. , Dargush G. F. 
Published: August 2009

AbstractThe effectiveness of hysteretic passive devices to protect and mitigate the response of a structure under seismic loading is well established by both analytical and experimental research. Nevertheless, a systematic and well‐established methodology for the topological distribution and size of these devices in order to achieve a desired structural response performance does not exist. In this paper, a computational framework is proposed for the optimal distribution and design of yielding metallic buckling restrained braces (BRB) and/or friction dampers within steel moment‐resisting frames (MRF) for a given seismic environment. A Genetic Algorithm (GA) is used to solve the resulting discrete optimization problem. Specific examples involving two three‐story, four‐bay steel MRFs and a six‐story, three‐bay steel MRF retrofitted with yielding and/or friction braces are considered. The seismic environment consists of four synthetic ground motions representative of the west coast of the United States with 5% probability of exceedance in 50 years. Non‐linear time‐history analyses are employed to evaluate the potential designs. As a result of the evolutionary process, the optimal placement, strength and size of the dampers are obtained throughout the height of the steel MRF. Furthermore, the developed computational approach for seismic design based upon GAs provides an attractive procedure for design of MRFs with hysteretic passive dampers. Copyright © 2009 John Wiley & Sons, Ltd.
Comparative leaf epidermis investigation in species of genus Crataegus L. (Rosaceae) from Bulgaria
Authors: Ganeva Ts. , Uzunova Kr. , Koleva D. 
Published: August 2009

AbstractThe leaf epidermis structure of six Crataegus species from Bulgaria has been studied by light and scanning electron microscopy. Cyclocytic stomatal type, different types of simple single trichomes, cuticle ornamentation and waxes are determined. The results allow clear delimitation and identification of the species. Some conjectures about the relationships on inter‐ and intrageneric level and references of epidermal structure with adaptation to various ecological conditions are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Potentilla L. (Rosaceae) in the former USSR; second part: comments Notes on Potentilla XXIV
Authors: Soják J. 
Published: August 2009

AbstractThis article contains comments on 88 species of Potentilla and three allied genera that grow in the territory of the former USSR. They deal mainly with taxonomic or nomenclatural issues, sometimes accompanied by notes on distribution. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The validity of Ochetophila Poepp. ex Endl. (Rhamnaceae: Colletieae)
Authors: Medan D. , Kellermann J. , Aagesen L. , Hilger H. H. 
Published: August 2009

AbstractIt is shown that doubts raised recently (Feddes Rep. 119: 622–624, 2008) about the validity of Ochetophila Poepp. ex Endl. as distinct from Discaria Hook. are based on unsound arguments. The distinctness of Ochetophila rests upon a solid cladistic analysis of the tribe Colletieae (Rhamnaceae) and adequately reflects the current knowledge of this group. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of the staff MFF in distributing NHS funding: taking account of differences in local labour market conditions
Authors: Elliott Robert , Ma Ada , Sutton Matt , Skatun Diane , Rice Nigel , Morris Stephen , McConnachie Alex 
Published: August 2009

AbstractThe National Health Service (NHS) in England distributes substantial funds to health‐care providers in different geographical areas to pay for the health care required by the populations they serve. The formulae that determine this distribution reflect populations' health needs and local differences in the prices of inputs. Labour is the most important input and area differences in the price of labour are measured by the Staff Market Forces Factor (MFF). This Staff MFF has been the subject of much debate. Though the Staff MFF has operated for almost 30 years this is the first academic paper to evaluate and test the theory and method that underpin the MFF. The theory underpinning the Staff MFF is the General Labour Market method. The analysis reported here reveals empirical support for this theory in the case of nursing staff employed by NHS hospitals, but fails to identify similar support for its application to medical staff. The paper demonstrates the extent of spatial variation in private sector and NHS wages, considers the choice of comparators and spatial geography, incorporates vacancy modelling and illustrates the effect of spatial smoothing. Copyright © 2009 John Wiley & Sons, Ltd.