bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frontline: GITR, a member of the TNF receptor superfamily, is costimulatory to mouse T lymphocyte subpopulations
Authors: Ronchetti Simona , Zollo Ornella , Bruscoli Stefano , Agostini Massimiliano , Bianchini Rodolfo , Nocentini Giuseppe , Ayroldi Emira , Riccardi Carlo 
Published: February 2004

AbstractGITR (glucocorticoid‐induced TNFR family related gene) is a member of the TNFR superfamily (TNFRSF) that is expressed in different cell types, including T lymphocytes. Because of a high homology in its cytoplasmic region with other known costimulatory members of the TNFRSF, we investigated whether GITR played a costimulatory role in T lymphocyte subpopulations. Our results show that the proliferation response of CD8+ and CD4+ peripheral T cell subpopulations was potentiated when a GITR costimulus was added to an anti‐CD3 stimulus. Furthermore, expression of the main activation‐induced receptor (IL‐2Rα) and production of IL‐2 and IFN‐γ were increased more with a GITR costimulus than with anti‐CD3 alone. GITR stimulation also enhanced anti‐CD3‐induced ERK phosphorylation, suggesting that GITR is involved in MAPK‐pathway activation. Interestingly, CD4+CD25+ regulatory T cell (Treg cell) proliferation was triggered by the GITR costimulus; Treg cell proliferation was paralleled by the loss of the anergic phenotype and suppressor activity. Nevertheless, unstimulated GITR–/– CD4+CD25+ and GITR+/+ CD4+CD25+ cells were equally able to exert suppressor activity on CD4+CD25– responder cells. These results indicate a novel function for GITR as costimulatory molecule of T cell subsets.
Effects of CD25 monoclonal antibody on proliferative and effector functions of alloactivated human T cells in vitro
Authors: Rowshani Ajda T. , Uss Alena , Yong Si‐La , van Lier René A.W. , ten Berge Ineke J. M. 
Published: February 2004

AbstractProphylactic treatment with CD25 mAb has led to a significant decrease of acute rejection rates after renal transplantation. However, despite its inhibitory effect on T cell proliferation and effector functions, rejections still occur. To obtain more insight in persistent alloreactivity, we evaluated the effects of the chimeric IgG1κ CD25 mAb Basiliximab® on proliferation and differentiation of alloactivated T cells from healthy individuals in vitro. Moreover, the capacity of other members of the common cytokine‐receptor γ‐chain family to overcome the inhibitory effects of CD25 mAb was studied. The CD25 mAb appeared to limit expansion of alloreactive lymphocytes rather than blocking entry into cell cycle, and it did so irrespective of the previous antigen experience of the cells. Both CD4+ and CD8+ alloresponsive lymphocytes showed diminished intracellular expression of IFN‐γ, TNF‐α, perforin and granzyme B. Remarkably, cytotoxicity was completely abolished. IL‐7, IL‐15 and IL‐21 could bypass the inhibitory effects of the CD25 mAb on both proliferation and cytotoxicity. In conclusion, persistent alloreactivity in the presence of therapeutic concentrations of CD25 mAb may be caused by alloreactive T cells that still produce cytokines that can damage the allograft. In addition, other members of the common cytokine‐receptor γ‐chain family can rescue the proliferative and cytotoxic activity of these alloreactive T cells.
A New Route to Protected Acyloins and Their Enzymatic Resolution with Lipases
Authors: Scheid Günther , Kuit Wouter , Ruijter Eelco , Orru Romano V. A. , Henke Erik , Bornscheuer Uwe , Wessjohann Ludger A. 
Published: February 2004

AbstractA series of 16 different 3‐acyloxy methyl ketones, the acyloin acetates and butyrates (±)‐5, was synthesised by a straightforward new method through alkylation of tert‐butyl 2‐acyloxyacetoacetates 3, followed by chemoselective dealkoxycarbonylation of the tert‐butyloxycarbonyl group in the presence of other ester groups. Subsequent hydrolysis of (±)‐5 can be achieved with base to give racemic acyloins 6, or with lipase catalysis to afford the corresponding non‐racemic acyloins (S)‐6. The remaining (R)‐acyloin esters 5 can be racemised and resubjected to the procedure, or hydrolysed chemically. The kinetic resolution with two of the six tested enzymes, CAL‐B and BCL (PS) lipase, proceeded selectively [enantiomeric ratio (E) values between 50 and > 200] and most of the acyloins (S)‐6 were obtained in very high enantiomeric excesses (up to > 99% ee). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Deprotonation of Indole Derivatives in Aqueous Cationic Surfactants
Authors: Spreti Nicoletta , Brinchi Lucia , Di Profio Pietro , Germani Raimondo , Savelli Gianfranco , Bunton Clifford A. 
Published: February 2004

AbstractDeprotonations of 5‐nitroindole, 1a, and its 2‐carboxylate ion, 2a, have been monitored in 0.01, 0.1, and 0.5 M NaOH in micellar solutions of cetyl trialkylammonium bromide, alkyl = Me, Et, nPr, nBu, CTABr, CTEABr, CTPABr, CTBABr. Extents of deprotonation (% f) have been fitted using the pseudophase model of micellar effects with interionic competition described by ion exchange or by independent association constants. Both treatments indicate that base dissociation constants in dilute OH− are lower than in water by factors of ca. 3−11, and decrease with increasing bulk of the head groups, and that these factors increase modestly as the OH− concentration increases to 0.5 M. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of (±)‐17‐Methylcamptothecins
Authors: Thomas Olivier P. , Dumas Cécile , Zaparucha Anne , Husson Henri‐Philippe 
Published: February 2004

Abstract(±)‐17‐Methylcamptothecins (29) were synthesized from the heteroyohimbane ajmalicine (5) through sequential oxidation steps and E‐ring functionalization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Suzuki Cross‐Coupling Reactions between Alkenylboronic Acids and Aryl Bromides Catalysed by a Tetraphosphane‐Palladium Catalyst
Authors: Peyroux Eugénie , Berthiol Florian , Doucet Henri , Santelli Maurice 
Published: February 2004

AbstractA range of alkenylboronic acids undergo Suzuki cross‐coupling with aryl bromides in good yields in the presence of [PdCl(C3H5)]2/cis,cis,cis‐1,2,3,4‐tetrakis[(diphenylphosphanyl)methyl]cyclopentane as a catalyst. A wide variety of 1‐arylprop‐1‐enes, 2‐arylprop‐1‐enes, 2‐arylbut‐1‐enes and 1,1‐diarylethylene or styrene derivatives have been prepared. Moreover, the reaction tolerates several functions, such as acetyl, formyl, nitrile or nitro. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered substrates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Structural Proliferation of 2,6‐Difluoropyridine through Organometallic Intermediates
Authors: Schlosser Manfred , Rausis Thierry 
Published: February 2004

AbstractContrary to a literature claim, 2,6‐difluoropyridine‐3‐carboxaldehyde can be readily prepared by consecutive treatment of 2,6‐difluoropyridine with lithium diisopropylamide and N,N‐dimethylformamide. Regioselective displacements of fluorine from the aldehyde by nucleophiles were carried out. To demonstrate the versatility of the organometallic approach, some two dozens of further 2,6‐difluoropyridine derivatives were prepared applying a combination of modern organometallic methods such as site selective hydrogen/metal and halogen/metal permutations and deprotonation‐triggered heavy halogen migrations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of the Four Stereoisomers of 6‐Acetoxy‐19‐methylnonacosane, the Most Potent Component of the Female Sex Pheromone of the New World Screwworm Fly, with Special Emphasis on Partial Racemization in the Course of Catalytic Hydrogenation
Authors: Mori Kenji , Ohtaki Takashi , Ohrui Hiroshi , Berkebile Dennis R. , Carlson David A. 
Published: February 2004

AbstractStarting from the enantiomers of citronellal and 1‐octyn‐3‐ol, all four stereoisomers of 6‐acetoxy‐19‐methylnonacosane were synthesized with sufficiently high stereochemical purities (more than 90% ee at C‐6; about 97% ee at C‐19) for their biological testing as the female sex pheromone of the screwworm fly (Cochliomyia hominivorax). All four isomers showed strong pheromone activity even at 1 μg, and no significant difference was observed in their potency. Adams’ platinum oxide was found to cause partial racemization of enantiomerically pure secondary propargylic alcohols in the course of their catalytic hydrogenation to saturated and secondary alcohols, while palladium‐charcoal was less potent in causing partial racemization. A new HPLC‐based discrimination of chiral and secondary alcohols proved to be useful in following such a subtle partial racemization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Scope and Limitations of the Peterson Olefination Reaction as a Route to Vinylidene Phosphanes
Authors: Izod Keith , McFarlane William , Tyson Brent V. 
Published: February 2004

AbstractThe Peterson olefination reaction has been investigated as a route to novel P‐substituted alkenes. The reaction between [(nPr2P)2(Me3Si)C]Li and paraformaldehyde cleanly gives the symmetrical vinylidene phosphane (nPr2P)2C=CH2 (4) in good to excellent yields. In contrast, reactions between [(R2P)(Me3Si)2C]Li (R = Me, nPr) and paraformaldehyde yield complex mixtures of products which do not contain the expected vinylidene species. However, the unsymmetrical vinylidene phosphanes [nPr2P(BH3)](Me3Si)C=CH2 (6), (Ph2P)(iPr2P)C=CH2 (7), [nPr2P(S)](Me3Si)C=CH2 (10), [Ph2P(S)][iPr2P(S)]C=CH2 (11) and [Ph2P(S)][Me2P(S)]C=CH2 (12) are readily accessible by the Peterson olefination reaction {compound 7 is obtained by deprotection of the corresponding borane adduct [Ph2P(BH3)][iPr2P(BH3)]C=CH2 with pyrrolidine}. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of the Unusual Octahydropyrano[2,3‐b]pyridine Ring System of ′Upenamide
Authors: Maia Alessandra Alves , Mons Stéphane , Pereira de Freitas Gil Rossimiriam , Marazano Christian 
Published: February 2004

AbstractWe describe for the first time the preparation of a model octahydropyrano[2,3‐b]pyridine 23 bearing substituents at positions 2 and 8, as in the natural alkaloid ′upenamide. The four inseparable diastereoisomers of 23, present in an 81:3:16:trace ratio, were analyzed by NMR spectroscopy experiments to fully determine their relative configurations and conformations. The major diastereoisomer of this non‐macrocyclic analog has the same configuration as in natural ′upenamide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
An Electrochemical Flow Analysis System for Putrescine Using Immobilized Putrescine Oxidase and Horseradish Peroxidase
Authors: Saby Coralie , Nguyen Tien V. , Luong John H. T. 
Published: February 2004

AbstractAn electrochemical flow analysis system was optimized together with immobilized putrescine oxidase and horseradish peroxidase for putrescine measurement. Four coupling agents, suberic acid bis(N‐hydroxysuccinimide ester), γ‐maleimidobutyric N‐hydroxysuccinimide ester, 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide and glutaraldehyde, were used for immobilizing the two enzymes on porous aminopropyl glass beads to form a bienzymic detection column. Although the glutaraldehyde crosslinking procedure offered the highest response, the immobilized bienzyme system was responsive to putrescine, spermidine (123% of the putrescine response at 250 μM) and cadaverine (98% of the putrescine response). In contrast, the enzymes immobilized on the glass beads using suberic acid bis(N‐hydroxysuccinimide ester) offered significantly better selectivity towards putrescine at the same concentration. For comparison, cadaverine and spermidine only provoked a response of 4.7% and 27.5% of the putrescine signal. The response to cadaverine and spermidine was further suppressed by lowering the detection pH from 8 to 7. At 250 μM, the response obtained for cadaverine and spermidine was only 1.5% and 3.9%, respectively, of the signal obtained for putrescine. A linear response to putrescine was obtained from 5 to 75 μM (0.629 μAs μM−1, R2=0.997) with a detection limit of 5 μM (S/N=3). The amperometric response retained 75% of its initial value after 600 repeated injections. The immobilized PUO/HRP (putrescine oxidase/horseradish peroxidase) was successfully demonstrated for measuring putrescine in fish extracts as an indicator of fish spoilage.
Amperometric Determination of Ascorbic Acid at an Electrodeposited Redox Polymer Film Modified Gold Electrode
Authors: Fei Junjie , Luo Liming , Hu Shengshui , Gao Zhiqiang 
Published: February 2004

AbstractA sensitive and selective electrochemical method for the determination of ascorbic acid was developed. It was shown that a hydrated osmium complex‐containing redox polymer film can be electrodeposited at the gold electrode and it exhibits excellent electrocatalytic activity towards the oxidation of ascorbic acid. In contrast to a bare gold electrode, the oxidation current of ascorbic acid increased greatly and the oxidation peak potential shifted negatively to about 0.01 V (vs. SCE) at the modified electrode. Amperometric measurements were performed at an applied potential of 0.01 V and a linear response was obtained in the range of 2–400 μM with a limit of detection (LOD) of 0.6 μM (S/N=3). The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of uric acid and dopamine. The proposed procedure was successfully applied to the determination of ascorbic acid in human urine samples.
Myoglobin‐Clay Electrode for Nitric Oxide (NO) Detection in Solution
Authors: Kröning Steffen , Scheller Frieder W. , Wollenberger Ulla , Lisdat Fred 
Published: February 2004

AbstractSodium montmorillonite was prepared via a colloidal chemical approach and deposited onto glassy carbon electrodes (GCE). Myoglobin was immobilized on the clay membrane modified electrode by spontaneous adsorption. Characterization of the myoglobin/clay/glassy carbon electrode (Mb/clay/GCE) showed a quasi‐reversible, electrochemical redox behavior of the adsorbed protein with a formal potential of −0.380±0.010 V (vs. Ag/AgCl). The heterogeneous electron transfer rate constant was found to be strongly influenced by the buffer concentration. The Mb/clay/GCE was stable for several days in solution. The interaction of the immobilized Mb with nitric oxide (NO) is characterized by coordination chemistry. The reaction was found to be reversible and could be applied for NO detection in the nanomolar concentration range by a voltammetric analysis. In addition a mixed protein electrode with co‐immmobilized myoglobin (Mb) and cytochrome c (Cyt.c) was developed. By choice of the electrode potential both proteins can be addressed independently.
Calix[4]resorcinarenetetrathiol Modified Gold Electrodes: Applications to the Adsorption and Electrochemical Determination of N‐Nitrosamines
Authors: Collyer Stuart D. , Bradbury Sally , Davis Frank , Hatfield John V. , Stirling Charles J. M. , Higson Séamus P. J. 
Published: February 2004

AbstractPreliminary results reported in this paper relate to the capture, retention and subsequent analysis of cationic N‐nitrosamines, from aqueous solutions, at calix[4]resorcinarenetetrathiol modified gold electrodes. Adsorptive stripping voltammetric regimes at electrodes of this type have allowed quantifications of N‐nitroso‐N‐butyl‐N‐propylamine down to concentrations of 10−10 M. Calix coatings have been shown, in certain cases, to allow an enhancement in the adsorptive uptake and subsequent analysis of N‐nitrosamines in solution in comparison to signals obtained at bare gold electrodes, although the coatings may become saturated when higher concentrations or when longer preaccumulative deposition times are employed.
Electrooxidation and Amperometric Detection of Ascorbic Acid at GC Electrode Modified by Electropolymerization of N,N‐Dimethylaniline
Authors: Roy Protiva Rani , Saha Madhu Sudan , Okajima Takeyoshi , Ohsaka Takeo 
Published: February 2004

AbstractThe polymer film of N,N‐dimethylaniline (DMA) is deposited on the electrochemically pretreated glassy carbon (GC) electrode by continuous electrooxidation of the monomer. This poly N,N‐dimethylaniline (PDMA) film‐coated electrode can be used as an amperometric sensor of ascorbic acid (AA). The polymer film (thickness (ϕ): 0.3±0.02 μm) having positive charge in its backbone attracts the anionic species AA. Thus, the anodic peak potential (350 mV vs. Ag|AgCl|NaCl(sat)) for the oxidation of AA at the bare electrode is largely shifted to the negative value (150 mV) at this electrode. The PDMA film‐coated electrode is stable in acidic, alkaline and neutral media and can sense AA at different pH's. The diffusion coefficients of AA in solution (D) and in film (Ds) were estimated by rotating disk electrode voltammetry: D=(5.5±0.1)×10−6 cm2 s−1 and Ds=(6.3±0.2)×10−8, (6.0±0.2)×10−8 and (4.7±0.2)×10−8 cm2 s−1 for 0.5, 1.5 and 3.0 mM AA, respectively. A permeability of AA through the PDMA film was found to decrease with increasing the concentration of AA in the solution. In the chronoamperometry, the current response for the oxidation of AA at different times elapsed after potential‐step application is linearly increased with the increase in AA concentration in a wide range of its concentration from 25 μM to 1.65 mM. In the hydrodynamic amperometry, a successive addition of 10 μM AA caused the successive increase in current response with equal amplitude and the sensitivity was calculated as 0.178 μA cm−2 μM−1. So, the fouling of the electrode surface caused by the oxidized product of AA is markedly eliminated at this PDMA film‐coated electrode. A flow injection analysis based on the present electrode was performed to estimate the concentration of vitamin C in fruit juice.
Burning behaviors of selected chlorosilanes and SiH‐containing siloxanes
Authors: Hshieh Fu‐Yu , Beeson Harold D. 
Published: February 2004

AbstractChlorosilanes are silanes containing the Si‐Cl functional group and SiH‐containing siloxanes are siloxanes containing the Si‐H functional group. Some chlorosilanes and SiH‐containing siloxanes present potentially high fire or explosion hazards during handling, storage, transport and process operations. Cone calorimeter tests have been used to study the burning behaviors of selected chlorosilanes and SiH‐containing siloxanes at various incident heat fluxes to simulate pool fire burning. The peak heat release rate of a silicon intermediate obtained from the cone calorimeter at 15 kW/m2 incident heat flux was very close to that measured by a relatively large‐scale field test. The flammability of monochlorosilanes was similar to that of organic hydrocarbons having comparable volatility. The flammability of chlorosilanes descends in the order of monochlorosilanes, dichlorosilanes and trichlorosilanes. SiH‐containing siloxanes ignited faster than non‐SiH‐containing siloxanes because of the reactive silicon‐hydrogen linkages. The ignition of SiH‐containing siloxanes was much more violent than the ignition of non‐SiH‐containing siloxanes. The SiH‐containing siloxanes exhibited a lower peak heat release rate, less total heat released and a lower peak smoke extinction coefficient compared with non‐SiH‐containing siloxanes having comparable volatility. Copyright © 2004 John Wiley & Sons, Ltd.
Large eddy simulation (2D) using diffusion–velocity method and vortex‐in‐cell
Authors: Milane R. E. 
Published: February 2004

AbstractA large eddy Simulation based on the diffusion‐velocity method and the discrete vortex method is presented. The vorticity‐based and eddy viscosity type subgrid scale model simulating the enstrophy transfer between the large and small scale appears as a convective term in the diffusion‐velocity formulation. The methodology has been tested on a spatially growing mixing layer using the two‐dimensional vortex‐in‐cell method and the Smagorinsky subgrid scale model. The effects on the vorticity contours, momemtum thickness, mean streamwise velocity profiles, root‐mean‐square velocity and vorticity fluctuations and negative cross‐stream correlation are discussed. Comparison is made with experiment and numerical work where diffusion is simulated using random walk. Copyright © 2004 John Wiley & Sons, Ltd.
Numerical analysis of the rotating viscous flow approaching a solid sphere
Authors: Wang Yan‐Xing , Lu Xi‐Yun , Zhuang Li‐Xian 
Published: February 2004

AbstractA numerical simulation is performed to investigate the flow induced by a sphere moving along the axis of a rotating cylindrical container filled with the viscous fluid. Three‐dimensional incompressible Navier–Stokes equations are solved using a finite element method. The objective of this study is to examine the feature of waves generated by the Coriolis force at moderate Rossby numbers and that to what extent the Taylor–Proudman theorem is valid for the viscous rotating flow at small Rossby number and large Reynolds number. Calculations have been undertaken at the Rossby numbers (Ro) of 1 and 0.02 and the Reynolds numbers (Re) of 200 and 500. When Ro=O(1), inertia waves are exhibited in the rotating flow past a sphere. The effects of the Reynolds number and the ratio of the radius of the sphere and that of the rotating cylinder on the flow structure are examined. When Ro ≪ 1, as predicted by the Taylor–Proudman theorem for inviscid flow, the so‐called ‘Taylor column’ is also generated in the viscous fluid flow after an evolutionary course of vortical flow structures. The initial evolution and final formation of the ‘Taylor column’ are exhibited. According to the present calculation, it has been verified that major theoretical statement about the rotating flow of the inviscid fluid may still approximately predict the rotating flow structure of the viscous fluid in a certain regime of the Reynolds number. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of corner angle on convection enhancement in wavy ducts with trapezoidal cross‐sections
Authors: Savino S. , Comini G. , Nonino C. 
Published: February 2004

AbstractThe effect of corner angle variations on pressure drop and heat transfer characteristics is investigated in the fully developed region of wavy ducts with trapezoidal cross‐sections. The resulting enhancement of convection, with respect to corresponding straight ducts, can be attributed to the formation of longitudinal vortices close to the two parallel surfaces. Numerical simulations show that Nusselt numbers and friction factors increase with the decrease of corner angle from 90 to 60°, before levelling out around 60°. Nusselt numbers and friction factors also increase with the Reynolds number, and the slopes of their representative curves increase above a critical value of the Reynolds number because of the onset of time‐periodic flow oscillations. Copyright © 2004 John Wiley & Sons, Ltd.