bluuebunny/crossref_metadata_2025_split huggingface dataset:
The chemokine receptor CCR7 controls lymph node‐dependent cytotoxic T cell priming in alloimmune responses
Authors: Höpken Uta E. , Droese Jana , Li Jian‐Ping , Joergensen Joanne , Breitfeld Dagmar , Zerwes Hans‐Günter , Lipp Martin 
Published: February 2004

AbstractThe chemokine receptor CCR7 and its ligands regulate migration and colocalization of T cells and mature dendritic cells to and within secondary lymphoid organs. The requirement of CCR7 in efficient priming of allospecific cytotoxic CD8+ T cells is poorly characterized. Here, we demonstrate a role for CCR7 in the initiation of an alloimmune response and in the development of transplant rejection. Remarkably, in a model of acute allogeneic tumor rejection, CCR7–/– mice completely failed to reject subcutaneously injected MHC class I mismatched tumor cells and cytotoxic activity of allospecific T cells was severely compromised. When solid tumors derived from wild‐type mice were transplanted, recipient CCR7–/– mice were capable of rejecting the allografts. In contrast, tumor allografts transplanted from CCR7–/– donors onto CCR7–/– recipients showed allograft survival up to 28 days, suggesting a critical function of CCR7 on donor‐type passenger leukocytes in the initiation of cytotoxic CD8+ T cell responses. In a heterotopic heart transplantation model CCR7 deficiency resulted in significantly prolonged but not indefinite allograft survival. Additional prolongation of graft survival was observed when hearts from CCR7–/– mice were used as donor organs. Our results define a key role for CCR7 in allogeneic T cell priming within the context of draining lymph nodes.
Maintenance of memory CTL responses by T helper cells and CD40‐CD40 ligand: antibodies provide the key
Authors: Bachmann Martin F. , Hunziker Lukas , Zinkernagel Rolf M. , Storni Tazio , Kopf Manfred 
Published: February 2004

AbstractCytotoxic T lymphocytes (CTL) are essential for control of primary infections by many pathogens and in particular by non‐cytopathic viruses. It has been proposed that long‐term maintenance of CTL memory and control of lymphocytic choriomeningitis virus (LCMV) is dependent upon the presence of T helper cells and interaction of antigen‐presenting cells and CTL via CD40 and its ligand CD40L. However, we demonstrate here that CD40‐CD40L interaction maintains CTL memory by induction of virus‐specific antibodies. In fact, loss of CTL memory responses and spread of virus in mice lacking CD40 or its ligand is prevented by repetitive therapeutic injections of LCMV‐specific antibodies. This indicates that antibodies are essential for long‐term control of non‐cytopathic virus and to maintain protective memory. Transfer of neutralizing antibodies or induction of antibodies by therapeutic vaccination within weeks after infection may therefore prove beneficial for the treatment of chronic virus infections such as HIV, hepatitis B, and hepatitis C.See accompanying article http://dx.doi.org/10.1002/eji.200324844
The Use of N‐Boc‐1,3‐Oxazolidines as Chiral Auxiliaries in Asymmetric Synthesis
Authors: Agami Claude , Couty François 
Published: February 2004

AbstractThis microreview presents the use of 1,3‐oxazolidines, prepared from enantiomerically pure β‐amino alcohols, as chiral inductors for the stereoselective transformation of adjacent prostereogenic C=C or C=O bonds. After a brief chronological presentation of the major advances in this field, a convenient synthesis of N‐Boc‐2‐acyl‐ and ‐2‐alkenyloxazolidines is presented, together with the use of these heterocycles in asymmetric synthesis. The important role played by the Boc group on the nitrogen of the heterocycle in these transformations is emphasized. In addition to its well known properties as a protecting group, this carbamate actively contributes to the efficiency of this chemistry. Thanks to its bulkiness and chelating properties, it contributes to an efficient stereodifferentiation of the close prostereogenic moiety, but can also directly react with this moiety either as an electrophile or as a nucleophile. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Selenobenzophenones and Diazoalkanes: Isolation of Tetraarylethylenes by the Reaction of Benzophenone Hydrazones with Diselenium Dibromide
Authors: Okuma Kentaro , Kojima Kazuki , Oyama Kosuke , Kubo Kento , Shioji Kosei 
Published: February 2004

AbstractThe reaction of selenobenzophenones with diazomethane afforded the corresponding diarylethylenes and symmetrical olefins. The reaction with diaryldiazomethanes gave three different types of tetraarylethylenes. This reaction proceeded through 1,3,4‐selenadiazoline intermediates, and retrocyclization was observed. The formation of 1,3,4‐selendiazolines was independently confirmed by the reaction of benzophenone hydrazones with diselenium dibromide, which afforded tetraarylethylenes in good yields. This method is applicable to the two‐step synthesis of tetraarylethylenes from benzophenones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A New Class of Enehydroxylamino Ketones − (R)‐2‐(1‐Hydroxy‐4,4,5,5‐tetraalkylimidazolidin‐2‐ylidene)ethanones: Synthesis and Reactions
Authors: Reznikov Vladimir A. , Roshchupkina Galina I. , Mazhukin Dmitrii G. , Petrov Pavel A. , Popov Sergei A. , Fokin Sergey V. , Romanenko Galina V. , Rybalova Tatjana V. , Gatilov Yuri V. , Shvedenkov Yuri G. , Irtegova Irina G. , Shundrin Leonid A. , Ovcharenko Victor I. 
Published: February 2004

AbstractThree approaches to the synthesis of (R)‐2‐(1‐hydroxy‐4,4,5,5‐tetraalkylimidazolidin‐2‐ylidene)ethanones 1 are described: (a) condensation of 1,2‐bishydroxylamines with β‐ketoaldehyde synthons, (b) treatment of metallated 1‐hydroxy‐2‐methyl‐4,5‐dihydroimidazoles with esters, and (c) 1,3‐dipolar cycloaddition between 1‐hydroxy‐4,5‐dihydroimidazole‐3‐oxide and DMAD. The reactivity of 1 with electrophiles has been studied. The exocyclic methylene (enamine) carbon atom is shown to be the major site of electrophilic attack. Synthesized chloro‐substituted 1‐hydroxy‐2‐acetylideneimidazolidines react with sodium cyanide to form the corresponding nitriles. Oxidation of these nitriles occurs with formation of persistent vinyl nitroxides, which are of interest as potential paramagnetic ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
An Experimental and Mechanistic Investigation of the Complexities Arising During Inhibition of the BriggsRauscher Reaction by Antioxidants
Authors: Cervellati Rinaldo , Höner Kerstin , Furrow Stanley D. , Mazzanti Francesco , Costa Stefano 
Published: February 2004

AbstractA method to determine the relative antioxidant capacity of radical scavengers based on the inhibition of the oscillations of the BriggsRauscher (BR) oscillating reaction was previously reported. A semiquantitative mechanistic interpretation of the inhibitory effects required two steps to obtain simulated inhibition times in very good agreement with the experimental ones. The first step is inhibitory, involving H‐atom transfer from antioxidant to the HOO. radical; the second step is a first‐order degradation of the antioxidant to unspecified products. Since the degradation may be due to oxidation and/or iodination of the antioxidant, we studied the kinetics of the subsystems IO$\rm{_{3}^{-}}$(H+)+antioxidant and I2(H+)+antioxidant. We used 2,5‐ and 2,6‐dihydroxybenzoic acids, caffeic acid (=3‐(3,4‐dihydroxyphenyl)prop‐2‐enoic acid), ferulic acid (=3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoic acid), pyrocatechol (=benzene‐1,2‐diol), and hydroquinone (=benzene‐1,4‐diol) as antioxidants. Spectra in the wavelength range 500–250 nm were repeated at given time intervals to follow the peaks of the iodine and oxidation products, which were mainly quinones. For the iodination of the above diphenols (=benzenediol derivatives) the substitution and/or addition reactions with I2 or HOI were found to be relatively slow compared to oxidation by IO$\rm{_{3}^{-}}$. Approximate rate constants for oxidation were obtained on the basis of a reasonable kinetic model by using a suitable numerical integration program. Although these complexities can arise also in the completely inhibited BR oscillator, we believe that the inhibitory effects are due to the HOO. scavenging action by diphenols or by quinones since HOO. radicals are also potential reducing agents. We propose two steps that could maintain a small reservoir of diphenol, while both quinone and diphenol deplete HOO. radicals. In short, the complexities do not affect the method for monitoring the relative activity of antioxidants based on the BR oscillating reaction. The effects of temperature on the inverse of the oscillatory time in the BR‐uninhibited system, on the inverse of inhibition times, and on the time length of the resumed oscillations for four antioxidants were also investigated. Apparent average activation energies were obtained.
Bauhinoxepins A and B: New Antimycobacterial Dibenzo[b,f]oxepins from Bauhinia saccocalyx
Authors: Kittakoop Prasat , Nopichai Sombat , Thongon Nuntawan , Charoenchai Panarat , Thebtaranonth Yodhathai 
Published: February 2004

AbstractTwo new antimycobacterial dibenzo[b,f]oxepins, bauhinoxepins A (=3,3,5‐trimethylbenzo[b]pyrano[g][1]benzoxepin‐6,11‐diol; 1) and B (=6‐methoxy‐7‐methyl‐2‐(3‐methylbut‐2‐enyl)dibenzo[b,f]oxepine‐1,8‐diol; 2), were isolated from the roots of Bauhinia saccocalyx, and their structures were elucidated by analysis of spectroscopic data. Bauhinoxepins A and B exhibited antimycobacterial activities with respective minimum‐inhibitory concentrations (MIC) of 6.25 and 12.5 μg/ml. They were inactive (at 20 μg/ml) against the malarial parasite, and also inactive (at 20 μg/ml) towards the Vero, KB, and BC cell lines.
Community health, community involvement, and community empowerment: Too much to expect?
Authors: Baillie Lynne , Broughton Sandra , Bassett‐Smith Joan , Aasen Wendy , Oostindie Madeleine , Marino Betty Anne , Hewitt Ken 
Published: February 2004

AbstractThe Primary Prevention of Cancer Program at the British Columbia Cancer Agency Centre for the Southern Interior (BCCA‐CSI), known as the Waddell Project, is now five years old and currently is in partnership with fourteen regional communities. Each of these communities has a range of community‐developed programs currently in place. The driving force behind the Waddell Project comes from the belief that emancipatory change is central to community health. That is, only those communities that are capable of challenging, questioning, and creating change can make the cancer‐prevention decisions that are relevant, useful, and sustainable within the context of the daily lives of their members. The resulting model for the project was influenced by Habermas's Theory of Communicative Action, from which are derived the project's guiding concepts of equality, negotiated content, collaborative process, inclusion of critique, importance of action, and mutual accountability. In this article, these concepts are revisited from the unique contexts and perspectives of the collaborating participants. Implications would suggest that the processes adopted to support empowered community engagement in cancer prevention are, in many ways, more beneficial than the implementation of the resulting initiative itself. Furthermore, it would seem that, rather than funding, it is prolonged and supportive commitment that is the most crucial factor for facilitating emancipatory change in community health. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 217–228, 2004.
Empowerment and public policy: An exploration of the implications of Section 115 of the Personal Responsibility and Work Opportunity Act
Authors: Kubiak Sheryl Pimlott , Siefert Kristine , Boyd Carol J. 
Published: February 2004

AbstractThe ability of individuals to gain mastery over their environment is considered empowerment. However, empowerment often is assessed without attention to the historical, social, or political context the individual is embedded within. This context often is contingent upon social policies that enhance or limit the choices an individual has to behave in ways constructed as efficacious. One example of such a policy is Section 115 of the Personal Responsibility and Work Opportunity Act of 1996, which mandated a lifetime ban on welfare benefits to individuals convicted of a drug‐related felony. This study examines the policy's implications from the perspective of empowerment. Specifically, we explore the characteristics of those targeted by the policy and what the denial of welfare benefits is likely to mean for this group. Using the sequential application of case study and survey methods, we first reviewed 250 court files of female drug offenders in one midwestern county, finding that most who were convicted of a drug felony received sentences of community probation, predominantly for use and possession. Second, we conducted face‐to‐face interviews with a subsample of 52 drug‐convicted women who otherwise were eligible for welfare benefits and compared them with the general welfare‐to‐work population. The women in our sample had more severe barriers to self‐sufficiency, including less education, higher rates of domestic violence, higher likelihood of recent major depression, and substantially higher rates of post‐traumatic stress disorder. Our findings suggest that the current national policy of denying welfare benefits based on a felony conviction status is unlikely to deter drug use or promote self‐efficacy unless accompanied by effective mental‐health services, help with employment, and supports to ensure a safe living environment. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 127–143, 2004.
Numerical effects in the simulation of Ginzburg–Landau models for superconductivity
Authors: Richardson Walter B. , Pardhanani Anand L. , Carey Graham F. , Ardelea Alexandre 
Published: February 2004

AbstractInadequate spatial mesh resolution for simulation of the time‐dependent Ginzburg–Landau equations is shown to give rise to spurious solutions. Phenomenological studies to examine the effect of the physical parameters and boundary conditions in 2D and 3D are presented to illustrate the solution structure and to highlight non‐linear effects related to evolving vortex patterns. We illustrate and explore this issue further by considering a related simplified model in which the number of vortices is equal to the ‘winding number’ that is associated with the applied boundary conditions. Using this model we demonstrate that the solution structure is non‐unique for several values of winding number. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and properties of novel sulfonated polyimides from 2,2′‐bis(4‐aminophenoxy)biphenyl‐5,5′‐disulfonic acid
Authors: Guo Xiaoxia , Fang Jianhua , Tanaka Kazuhiro , Kita Hidetoshi , Okamoto Ken‐ichi 
Published: February 2004

AbstractNovel sulfonated polyimides (SPIs) were prepared from 1,4,5,8‐naphthalenetetracarboxylic dianhydride (NTDA), 2,2′‐bis(4‐aminophenoxy)biphenyl‐5,5′‐disulfonic acid (oBAPBDS) with nonlinear configuration, and common nonsulfonated diamines. Water uptake (WU) in liquid and vapor, water stability, and proton conductivity σ of the resulting SPI membranes were investigated. They were soluble in m‐cresol and dimethylsulfoxide, and their WUs in liquid were much larger than those of the SPIs from other sulfonated diamines with linear configuration such as 4,4′‐bis(4‐aminophenoxy)biphenyl‐3,3′‐disulfonic acid (BAPBDS). NTDA‐oBAPBDS membrane was soluble in water at room temperature, whereas all the oBAPBDS‐based copolyimide membranes were insoluble in water and maintained mechanical strength after being soaked in distilled water at 80 °C for 40–1000 h. This much improved water stability was due to the enhanced solubility stability of membrane toward water. The water vapor sorption isotherms were rather similar between the SPIs with the nonlinear and linear configurations of sulfonated diamine moieties. The present SPIs with IECs of 1.8–2.6 meq/g, including NTDA‐BAPBDS, showed reasonably high proton conductivities under the highly humid conditions and roughly fell on the same σ–WU relation line. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1432–1440, 2004
Facile synthetic route to polymerizable hindered amine light stabilizers for transition‐metal‐catalyzed olefin copolymerization
Authors: Auer M. , Nicolas R. , Vesterinen A. , Luttikhedde H. , Wilén C.‐E. 
Published: February 2004

AbstractThis work describes a facile method by which a polymerizable hindered amine light stabilizer, 4‐(10‐undecylidene)‐2,2,6,6‐tetramethylpiperidine, was prepared in a single‐step procedure by means of a Wittig reaction. The monomer was successfully copolymerized with ethylene with a rac‐[dimethylsilylenebis(4,5,6,7‐tetrahydro‐1‐indenyl)]zirconium dichloride/methylalumoxane catalyst system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1350–1355, 2004
Influence of interfaces on the rates of crosslinking in poly(dimethyl siloxane) coatings
Authors: Simpson T. R. E. , Tabatabaian Z. , Jeynes C. , Parbhoo B. , Keddie J. L. 
Published: February 2004

AbstractWe have determined with infrared spectroscopic ellipsometry how the nature of the interface between a thin poly(dimethyl siloxane) (PDMS) coating and its substrate affects the rate of PDMS crosslinking reactions. Reactions between vinyl (CHCH2) end groups on PDMS and silyl (SiH) groups in a crosslinker (hydrosilylation) and between SiH groups and silanol (SiOH) groups, during the so‐called postcure crosslinking stage, have been probed in situ. The overall consumption of SiH follows first‐order reaction kinetics. The first‐order reaction coefficient (k1) for the hydrosilylation crosslinking reaction is the same for coatings on three different substrates: native oxide on silicon (SiO2/Si), polystyrene (PS), and poly(ethylene terephthalate). For the slower postcure reactions, however, the rate of SiH consumption depends on the substrate. In 2.5‐μm PDMS coatings on PS, k1 is about seven times greater than k1 in the same coating on SiO2/Si. In PDMS coatings on a PDMS substrate, when the effect of the interface is thus minimal, k1 is 16 times higher than on SiO2/Si. The dependence of k1 on the type of interface is probably the result of the interfacial segregation and complexation of the Pt catalyst for the postcure reactions. We propose that polar surfaces more strongly attract Pt and form complexes that inhibit the postcure reactions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1421–1431, 2004
Anomalous penetrant diffusion as a probe of the local structure in a blend of poly(ethylene oxide) and poly(methyl methacrylate)
Authors: Cao Haihui , Lin Guoxing , Jones Alan A. 
Published: February 2004

AbstractPulse field gradient (PFG) NMR measurements have been made to study the diffusion of diethyl ether in blends of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA). The blends have 10–30 wt % PEO, a composition range within which these materials are amorphous glasses. The diffusion of diethyl ether through the blends is quite rapid, with diffusion constants in the range of 10−7to 10−8cm2/s. In PFG NMR experiments, the apparent diffusion constant depends on the timescale over which diffusion is observed. The values decrease to a plateau as the time increases, this being the signature of tortuous diffusion. Tortuous diffusion is usually observed in heterogeneous systems in which there are regions that support fast diffusion and regions that support slow diffusion or act as barriers. In these blends, PEO is known to undergo rapid segmental motion typical of a rubbery state well below the glass transition, whereas the segmental motion of PMMA is slower by many orders of magnitude. Mobile PEO provides a pathway for the diffusion of structurally similar diethyl ether, whereas solid‐like PMMA acts as a barrier. The size of the domains can be estimated either from a lattice model or from equations for tortuous diffusion. Micrometer sizes are indicated that are unexpectedly large, given the size of the polymer chains and the size of the concentration fluctuations, both of which are thought to be in the tens of nanometers. The lattice model and the equations for tortuous diffusion assume a random dispersion of impenetrable or less penetrable objects. This may not be the appropriate morphology for the diffusion pathway. Recently, large sizes have been indicated by PFG NMR experiments, in which a penetrant is thought to diffuse in a curvilinear fashion. In these blends, the pathway for diethyl ether is along the PEO backbone. A plot of the logarithm of the mean‐square displacement versus the logarithm of time has a slope of about 0.6, close to the value of 0.5 for pure curvilinear diffusion. Exponents with values in this range can also be associated with diffusion in a fractal space, which, in this situation, still consists of mobile PEO. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1053–1067, 2004
Properties of antimicrobial plastics containing traditional food preservatives
Authors: Vartiainen Jari , Skytta Eija , Enqvist Jouni , Ahvenainen Raija 
Published: February 2004

AbstractTraditional food preservatives, sodium benzoate, sodium nitrite, potassium sorbate and sodium lactate, were incorporated into synthetic plastics, low‐density polyethylene (LDPE), poly(maleic acid‐co‐olefine), polystyrene (PS) and polyethylene terephthalate (PET), aimed at producing antimicrobial packaging material for foodstuffs. The study was undertaken on plaques (thickness 2 mm) and films (thickness 70–120 µm), whose antimicrobial test results clearly differed. Plaques containing 15% sodium nitrite inhibited both Aspergillus niger and Bacillus subtilis, whereas the same concentration of sodium benzoate and potassium sorbate had activity only against B. subtilis. Sodium lactate‐containing samples did not have any antimicrobial activity and none of the samples inhibited Escherichia coli. Antimicrobial substances added into PS and PET produced the strongest activities; however, due to the brittle structure of these materials, they were not tested further. Thus, more thorough tests for antimicrobial activity, migration and oxygen and water vapour permeability were carried out using LDPE films with 2.5–15% sodium benzoate and sodium nitrite. The effects of both substances on permeability properties were negligible. Although the total migration into food simulants measured from the films in many cases exceeded the limit value of 10 mg/dm2, no antimicrobial activity was observed. Copyright © 2003 John Wiley & Sons, Ltd.