bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel human CD4+ T‐cell inducer subset with potent immunostimulatory properties
Authors: Ndhlovu Lishomwa C. , Leal Fabio E. , Eccles‐James Ijeoma G. , Jha Aashish R. , Lanteri Marion , Norris Philip J. , Barbour Jason D. , Wachter Douglas J. , Andersson Jan , Taskén Kjetil , Torheim Eirik A. , Aandahl Einar M. , Kallas Esper G. , Nixon Douglas F. 
Published: October 2009

AbstractThe complexity of immunoregulation has focused attention on the CD4+ T “suppressor” regulatory cell (Treg), which helps maintain balance between immunity and tolerance. An immunoregulatory T‐cell population that upon activation amplifies cellular immune responses was described in murine models more than 30 years ago; however, no study has yet identified a naturally occurring T “inducer” cell type. Here, we report that the ectoenzyme CD39/NTPDase1 (ecto‐nucleoside triphosphate diphosphohydrolase 1) helps to delineate a novel population of human “inducer” CD4+ T cells (Tind) that significantly increases the proliferation and cytokine production of responder T cells in a dose‐dependent manner. Furthermore, this unique Tind subset produces a distinct repertoire of cytokines in comparison to the other CD4+ T‐cell subsets. We propose that this novel CD4+ T‐cell population counterbalances the suppressive activity of suppressor Treg in peripheral blood and serves as a calibrator of immunoregulation.
Long‐lasting immunity by early infection of maternal‐antibody‐protected infants
Authors: Navarini Alexander A. , Krzyzowska Malgorzata , Lang Karl S. , Horvath Edit , Hengartner Hans , Niemialtowski Marek G. , Zinkernagel Rolf M. 
Published: October 2009

AbstractNewborn higher vertebrates are largely immuno‐incompetent and generally survive infections – including poxviruses – by maternal antibody protection. Here, we show that mice survived epidemics as adults only if exposed to lethal orthopoxvirus infections during infancy under the umbrella of maternal protective antibodies. This implies that both the absence of exposure to infection during early infancy or of effective vaccination renders the population highly susceptible to new or old re‐emerging pathogens.
Innate signaling regulates cross‐priming at the level of DC licensing and not antigen presentation
Authors: Keller Susanne A. , Schwarz Katrin , Manolova Vania , von Allmen Caroline E. , Kinzler Matthias G. , Bauer Monika , Muntwiler Simone , Saudan Philippe , Bachmann Martin F. 
Published: October 2009

AbstractInnate stimuli, such as TLR ligands, are known to greatly facilitate cross‐priming. Currently it is unclear whether innate stimuli enhance cross‐priming at the level of cross‐presentation or at the level of T‐cell priming. In this study, we addressed this question by measuring cross‐presentation as well as cross‐priming by virus‐like particles (VLP) displaying peptide p33 derived of lymphocytic choriomeningitis virus. Innate stimuli were varied by either packaging different TLR ligands into virus‐like particles or using mice deficient in two key molecules of TLR‐signaling, namely the adaptor molecule MyD88 as well as IFN‐α/β receptor. While efficient cross‐presentation occurred despite strongly reduced activation of DC in the absence of TLR ligand‐mediated signals, T‐cell priming was abolished. Thus, innate stimuli regulate cross‐priming at the level of DC licensing for T‐cell activation and not antigen presentation.
Expression of apoptosis‐related genes in an Ethiopian cohort study correlates with tuberculosis clinical status
Authors: Abebe Markos , Doherty T. Mark , Wassie Liya , Aseffa Abraham , Bobosha Kidist , Demissie Abebech , Zewdie Martha , Engers Howard , Andersen Peter , Kim Louise , Huggett Jim , Rook Graham , Yamuah Lawrence K. , Zumla Alimuddin 
Published: October 2009

AbstractMycobacterium tuberculosis remains one of the world's deadliest pathogens in part because of its ability to persist in the face of an active immune response. It has been suggested that apoptosis of infected macrophages is one way in which the host deals with intracellular pathogens and that M. tuberculosis can inhibit this process. To assess the relevance of this process for human disease, we compared the expression of multiple genes involved in the activation of the extrinsic (“death receptor initiated”) pathway of apoptosis in 29 tuberculosis patients, 70 tuberculosis contacts and 27 community controls from Ethiopia. We found that there is a strong upregulation of genes for factors that promote apoptosis in PBMC from individuals with active disease, including TNF‐α and its receptors, Fas and FasL and pro‐Caspase 8. The anti‐apoptotic factor FLIP, however, was also upregulated. A possible explanation for this dichotomy was given by fractionation of PBMC using CD14, which suggests that macrophage/monocytes may regulate several key molecules differently from non‐monocytic cells (especially TNF‐α and its receptors, a finding confirmed by protein ELISA) potentially reducing the sensitivity to apoptotic death of monocyte/macrophages – the primary host cell for M. tuberculosis. This may represent an important survival strategy for the pathogen.
Divanadium(V) and Trapped Valence Linear Tetravanadium(IV,V,V,IV) Complexes
Authors: Sarkar Anindita , Pal Samudranil 
Published: October 2009

AbstractIn an acetonitrile/water mixture, reactions of the N,N′‐bis(diacetyl)hydrazine (H2diah), bis(acetylacetonato)oxidovanadium(IV) [VO(acac)2] and monodentate N‐coordinating heterocycles (hc) in a 1:2:2 mol ratio provide yellow divanadium(V) complexes of formula [(hc)O2V(μ‐diah)VO2(hc)] (1, hc = imidazole; 2, hc = pyrazole; 3, hc = 3,5‐dimethyl pyrazole). On the other hand, in the same solvent mixture reactions of the same reagents in a 1:4:2 mol ratio produce green linear tetravanadium(IV,V,V,IV) complexes of formula [(acac)2OV(μ‐O)VO(hc)(μ‐diah)(hc)OV(μ‐O)VO(acac)2] (4, hc = imidazole; 5, hc = pyrazole; 6, hc = 3,5‐dimethyl pyrazole). The complexes 1–6 have been characterized by elemental analysis, magnetic susceptibility, and various spectroscopic and electrochemical measurements. The X‐ray crystal structures of 1, 3 and 6 have been determined. In all three structures, the diazine ligand diah2– is in trans configuration. Metal‐centred bond parameters are consistent with the localized electronic structure of the two trans‐bent {OV(μ‐O)VO}3+ cores present in 6. The pentavalent metal centres in 1, 3 and 6 are in a distorted trigonal‐bipyramidal N2O3 coordination environment, while the terminal tetravalent metal centres in 6 are in a distorted octahedral O6 coordination sphere. The eight‐line EPR spectra of the tetravanadium species (4–6) in dimethyl sulfoxide at ambient temperature indicate the rare valence localized electronic structure in the fluid phase. All the complexes are redox active and display metal‐centred electron transfer processes in dimethyl sulfoxide solution. A reduction within –0.78 to –0.94 V (vs. Ag/AgCl) is observed for the divanadium(V) species 1–3, while a reduction and an oxidation are observed in the potential ranges –0.82 to –0.90 V and 0.96 to 1.12 V (vs. Ag/AgCl), respectively, for the tetravanadium species 4–6. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
para‐Bromophenyl[tris(pyrazolyl)]borate Complexes of Group 1 Metals, Thallium and Magnesium: Synthesis and Characterization of Transfer Agents for “Third‐Generation” Tp Ligands
Authors: Zagermann Johannes , Kuchta Matthew C. , Merz Klaus , Metzler‐Nolte Nils 
Published: October 2009

AbstractIn the course of finding ligands suitable for application in bioorganometallic systems, “third‐generation” Tp‐transfer agents p‐BrC6H4TpM [M = Na (1), K (2), Rb (3), Cs (4), Tl (5); Tp = tris(pyrazolyl)borate], p‐BrC6H4Tp*Tl (6) [Tp* = tris(3,5‐dimethylpyrazolyl)borate], (p‐BrC6H4Tp)2Mg (7), p‐BrC6H4TpMeK (8) [TpMe = tris(3‐methylpyrazolyl)borate] and p‐BrC6H4Tp*K (9) bearing a functionalizable 4‐bromophenyl group on the boron atom were synthesized and characterized. Monovalent 6 and magnesium‐sandwich compound 7 were structurally characterized in the solid state by X‐ray diffraction. Compound 6 forms a dimer by κ2‐coordination of Tl to one Tp ligand and to the bromine atom of a neighbouring 4‐bromophenyl group.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Chiral, Neutral, and Paramagnetic Gold Dithiolene Complexes Derived from Camphorquinone
Authors: Perochon Romain , Poriel Cyril , Jeannin Olivier , Piekara‐Sady Lidia , Fourmigué Marc 
Published: October 2009

AbstractReaction of racemic (dl)‐ or enantiopure (D)‐camphorquinone with P4S10in dimethylimidazolidinone followed by addition of NiCl2·6H2O or KAuCl4affords the corresponding bornylenedithiolato metal complexes [(dl‐bordt)2Ni], [(D‐bordt)2Ni], [(dl‐bordt)2Au], and [(D‐bordt)2Au] in their neutral form. Cyclic voltammetry and UV/Vis/NIR spectrometry show that the bornylenedithiolato ligand acts as a highly electron‐rich dithiolene ligand. Complete assignment of the1H and13C NMR signals of the diamagnetic enantiopure [(D‐bordt)2Ni] is reported thanks to a combination of 2D NMR spectroscopy experiments. X‐ray crystal structure determinations were performed for the four complexes, showing that the two diastereomeric mixtures, [(dl‐bordt)2Ni] and [(dl‐bordt)2Au], are isomorphous (space groupP21/c), as are also the two enantiopure complexes, [(D‐bordt)2Ni] and [(D‐bordt)2Au] (space groupP21). Positional disorder of the two (D)‐ and (L)‐bornylenedithiolate enantiomers on the same position is observed in the structure of the diastereomeric mixtures, with the complex located on the inversion center. The temperature dependence of the magnetic susceptibility of the paramagnetic gold complexes [(dl‐bordt)2Au] and [(D‐bordt)2Au] demonstrates the presence of antiferromagnetic interactions, to a larger extent in the diastereoisomeric mixture [(dl‐bordt)2Au] than in the enantiopure complex [(D‐bordt)2Au], as a consequence of stronger lateral S···S intermolecular interactions in the former. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
NMR Chemical Shifts of Metal Centres in Polyoxometalates: Relativistic DFT Predictions
Authors: Vankova Nina , Heine Thomas , Kortz Ulrich 
Published: October 2009

AbstractA DFT approach incorporating relativistic corrections and solvent effects was tested for NMR calculations on transition‐metal centres in polyoxometalates. For a monoplatinum decavanadate derivative and a set of dilacunary polyoxotungstates 51V and 183W chemical shifts were calculated at several levels of theoretical treatment regarding solvent, counterion and exchange‐correlation functional. Calculations were performed first in the gas phase to model isolated ions and next in a continuum model for water to evaluate the importance of solvation for the quality of the computed chemical shifts. We show that the use of the orbital‐dependent Kohn–Sham exchange‐correlation functional SAOP in ZORA spin‐orbit calculations with solvent effects included via COSMO substantially improves the agreement between computed results and experimental benchmarks for 51V chemical shifts (atleast, in the case of [H2PtIVV9O28]5–). In the case of dilacunary polyoxotungstates our calculations confirm the necessity of modelling an ion pair in which a counterion is specifically included in the POM lacuna to attain accurate predictions of the corresponding 183W NMR spectra. We show that if the counterion is relatively small (like Li+ and Na+), the explicit location of a water molecule in its vicinity (in addition to the overall COSMO treatment) improves further the accuracy of the correlation between computed and experimental shifts (to less than 5 ppm of the encompassed δ range).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Sulfonic Acid Analogs of Terephthalic and Trimesic Acid as Linkers in Metal‐Organic Frameworks – Synthesis of Thermally Robust MOFs
Authors: Mietrach Andrea , Muesmann Thomas W. T. , Christoffers Jens , Wickleder Mathias S. 
Published: October 2009

Abstractp‐Benzenedisulfonic acid and 1,3,5‐benzenetrisulfonic acid are prepared in an efficient and scalable two‐step protocol from respective bromobenzene derivatives. These acids are used in analogy to terephthalic and trimesic acid for the formation of metal‐organic frameworks with copper(II) centers. Due to the enhanced acidity of sulfonic acids, weakly basic malachite can be used as inorganic precursor material. After dehydration at about 100 °C, the anhydrous frameworks exhibit significantly increased thermal stability (up to 400 °C) relative to the commonly known carboxylate MOFs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Ligandless Iron‐Catalyzed Desulfinylative C–C Allylation Reactions using Grignard Reagents and Alk‐2‐enesulfonyl Chlorides
Authors: Volla Chandra M. R. , Marković Dean , Dubbaka Srinivas Reddy , Vogel Pierre 
Published: October 2009

AbstractAlk‐2‐enesulfonyl chlorides 1–4 were synthesized by the BCl3‐promoted ene reaction of alkenes with SO2. These sulfonyl chlorides were then used as electrophilic partners in iron‐catalyzed desulfinylative cross‐coupling reactions with different Grignard reagents (aromatic, aliphatic, andheteroaromatic). The reaction can be catalyzed with even 2 mol‐% of the simple iron salt Fe(acac)3. The regioselectivity of these allylations was studied by using sulfonyl chlorides 3 and 4 with aryl Grignard reagents. The scope of these allylations was further extended by the coupling of ester‐substituted alk‐2‐enesulfonyl chloride 10 with aromatic Grignard reagents. Symmetrical products were synthesized by double C–C allylation with the use of 2‐methylidenepropane‐1,3‐disulfonyl chloride (12). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
The Slow Rearrangement of a Sterically Hindered Nitro‐Cyclohexadienone and the Absence of Phenol Oxidation by Nitrogen Monoxide
Authors: Peters Steven J. , Blood Trisha M. , Kassabaum Mark E. 
Published: October 2009

AbstractThe exposure of 2,4,6‐tri‐tert‐butylphenol (1) in solution to NO2· results in the rapid formation of 2,4,6‐tri‐tert‐butyl‐4‐nitro‐2,5‐cyclohexadienone (2), which then undergoes a slow (ca. 3 d) rearrangement in the absence of air. The mechanism that describes this rearrangement is understood for the first time and involves the initial isomerization of 2 to form a(–ONO)‐substituted cyclohexadieneone (6). The nitrite moiety undergoes bond homolysis releasing NO· while forming an oxyl radical intermediate. An intermolecular, concerted hydrogen abstraction, which proceeds between 6 and this oxyl radical, results in the simultaneous formation of all stable products, some of which have not been previously observed. Furthermore, when 1 is exposed to NO· under anaerobic conditions, no reaction is observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Fabrication of Nanocomposite Containing Naphthoquinone and Nanogold Supported on Poly(2,6‐pyridinedicarboxylic acid) Film for Voltammetric Determination of N‐Acetyl‐L‐Cysteine
Authors: Raoof Jahan Bakhsh , Ojani Reza , Chekin Fereshteh , Jahanshahi Mohsen , Rashid‐Nadimi Sahar 
Published: October 2009

AbstractA modified electrode was fabricated by grafting of poly (2,6‐pyridinedicarboxylic acid) film (PDC) by electropolymerization of 2,6‐pyridinedicarboxylic acid on the glassy carbon electrode (GCE). Then, gold nanoparticles (NG) and 1,2‐naphthoquinone‐4‐sulfonic acid sodium (Nq) were immobilized on the PDC/GCE to prepare Nq/NG/PDC/GCE by immersing electrode into NG and Nq solution, respectively. The Nq species on NG/PDC/GCE could catalyze electrooxidation of N‐acetyl‐L‐cysteine (NAC) with lowering the over potential by about 600 mV. This method used for detection of NAC in dynamic range from 4.0×10−6 M to 1.30×10−4 M with a detection of limit (2σ) 8.0×10−7 M.
Adenosine Reagentless Electrochemical Aptasensor Using a Phosphorothioate Immobilization Strategy
Authors: Ceretti Helena , Ponce Belén , Ramírez Silvana A. , Montserrat Javier M. 
Published: October 2009

AbstractThis work deals with the characterization of a phosphorothioate anchoring strategy for aptamer molecules linked to gold, in the context of electrochemical sensors, using adenosine aptamer as model system. Surface density of immobilized phosphorothioate oligonucleotide sequences has been explored for a range of oligonucleotide concentrations (0.055–55 μM), finding a consequent variation of molecular surface density (3.5×1011–2.8×1013 molecules/cm2). Most suitable aptamer concentration for adenosine recognition was also explored and found to be around 5.5 μM. As proof of concept of phosphorothioate strategy, electrochemical response to adenosine concentration was measured using a ferrocene‐labeled oligonucleotide sequence, and phosphorothioate anchoring thermal stability was compared to thiol immobilization.
Etched succinate‐functionalized silica hydride stationary phase for open‐tubular CEC
Authors: Chen Jian‐Lian 
Published: October 2009

AbstractAn open‐tubular (OT) CEC column was designed to anchor ionizable succinate‐functionalized ligands onto a silica hydride‐based stationary phase through surface etching, silanization, and hydrosilation reactions beginning from a bare fused‐silica tube. The modified columns that were produced in each step were monitored by analysis of the effect of performance of EOF on the changes of pH values, concentrations, and the amount of ACN added in the running buffers. By tracking the EOF patterns between columns, the author determined that the surface composition of the final product column was a combination of silanols, silica hydrides, and succinate ligands. Furthermore, lower loading volumes of the succinate ligands prepared for the hydrosilation reaction served to complete the mixed‐mode OT‐CEC columns, and subsequently to carry out the separation of six phenyl alcohols. Studies on the elution order of these alcohols identified the presence of chromatographic interactions in addition to electrophoresis. Based on the employment of a solvation parameter model, these interactions likely included dispersion interactions, dipole‐type interactions, and interactions arising through the polarizable electrons in the solute. The optimum buffer conditions for CEC separations of phenyl alcohols, carbonyl‐substituted phenols, and a mixture of nucleosides and thymine were a phosphate buffer (50 mM, pH 10.51), a borate buffer (50 mM, pH 8.62), and a borate buffer (50 mM, pH 9.50), respectively. Overall, the hydride‐based stationary phases with ionizable ligands were successfully applied to the OT‐CEC separations, and these results confidently propose an ideal route to the synthesis of novel OT‐CEC columns.
Cellulose dimethylphenylcarbamate‐immobilized zirconia for chiral separation in reversed‐phase CEC
Authors: Gwon Jurim , Jin Juhyeon , McNeff Clayton V. , Park Jung Hag 
Published: October 2009

AbstractCellulose dimethylphenylcarbamate (CDMPC)‐immobilized zirconia (CDMPCZ) was used as a chiral stationary phase for enantioseparation of a set of nine racemic compounds in reversed‐phase CEC. Influences of the type and composition of organic modifier and the applied voltage on enantioseparation were examined. Separation data on CDMPCZ were also compared with those on CDMPC‐immobilized silica (CDMPCS). Enantiomers of the analytes investigated are well separated in ACN/phosphate buffer mobile phases. Better enantioselectivity and resolution were obtained with ACN than MeOH as the organic modifier. Retention was longer but better enantioselectivity and resolution were obtained on CDMPCZ than CDMPCS.
Determination of related substances of levodopa including the R‐enantiomer by CE
Authors: Wongwan Sudaporn , Hammitzsch‐Wiedemann Manuela , Scriba Gerhard K. E. 
Published: October 2009

AbstractA CE assay for the simultaneous determination of the impurities of levodopa listed in the European Pharmacopoeia including the (R)‐enantiomer was developed and validated. The analysis was performed in a fused‐silica capillary employing sulfated β‐cyclodextrin as chiral selector at an applied voltage of 20 kV and a temperature of 18°C. The optimized background electrolyte consisted of 0.1 M sodium phosphate buffer, pH 2.0, containing 6 mg/mL sulfated β‐cyclodextrin. L‐phenylalanine was used as the internal standard. The assay was validated in the range of 0.1–1.0% for the impurities at a concentration of levodopa of 2 mg/mL. The effect of different batches of sulfated β‐cyclodextrin was investigated using levodopa and L‐tyrosine as critical pair. The method was applied to determine the purity of several samples of levodopa including the chemical reference substance of the European Pharmacopoeia.
Determination of residual cell culture media components by MEKC
Authors: Zhang Junge , Chakraborty Utpal , Foley Joe P. 
Published: October 2009

AbstractFolic acid, hypoxanthine, mycophenolic acid, nicotinic acid, riboflavin, and xanthine are widely used as cell culture media components in monoclonal antibody manufacturing. These components are subsequently removed during the downstream purification processes. This article describes a single MEKC method that can simultaneously determine all the listed compounds with acceptable LOD and LOQ. All the analytes were successfully separated by MEKC using running buffer containing 40 mM SDS, 20 mM sodium phosphate, and 20 mM sodium borate at pH 9.0. The MEKC method was compared to the corresponding CZE method using the same running buffer containing no SDS. The effect of SDS concentration on separation, the pH of the running buffer, and the detection wavelength were studied and optimal MEKC conditions were established. Good linearity was obtained with correlation coefficients of more than 0.99 for all analytes. Specificity, accuracy, and precision were also evaluated. The recovery was in the range of 89–112%. The precision results were in the range of 1.7–4.8%. The experimentally determined data demonstrated that the MEKC method is applicable to the determination of the six analytes in in‐process samples from monoclonal antibody manufacturing processes.
Estimating seepage and hydraulic potentials near incised ditches in a homogeneous, isotropic aquifer
Authors: Römkens M. J. M. 
Published: October 2009

AbstractSoil erosion on upland areas is a highly complex phenomenon involving many component processes. One of the least explored processes is the role of subsurface flow. Rain or irrigation water entering the soil profile either accrues to groundwater or exits at some point downslope as seepage. In the latter case, the positive water pressure may lead to detachment of soil particles, aggregates, or bulk soil, that often is a prelude to incipient rilling or gullying. This article concerns the analysis of seepage to ditches with a water level lower than the adjacent field water table and the hydraulic pressures near the ditches in order to assess their contributing role in gully development. The approach taken is to analyze the subsurface flow regime under steady‐state conditions using the theory of conformal transformations. First, seepage to a fully filled circular drain in a homogeneous isotropic layer overlaying an impermeable layer was analyzed. Subsequently, the case of drainage to a ditch partially filled with water and the effect of a buffer strip adjacent to the ditch on seepage reduction were studied using the same methodology. Two approaches were considered to approximate the water level in the buffer strip: (1) a confined boundary represented by a straight line between the ditch water level and the field surface water level; and (2) a free boundary in which the groundwater level was approximated by the pressure potential relationship for flow from a ponded surface area to a sink placed at the surface at a distance equal to the width of the buffer strip. The latter analysis yielded explicit expressions of seepage, and the groundwater hydraulic and stream potential functions in terms of the spatial coordinates. This relationship should facilitate the analysis of the role of the subsurface water regime on seepage, soil erosion, and gully development. Published in 2009 by John Wiley & Sons, Ltd.