bluuebunny/crossref_metadata_2025_split huggingface dataset:
CD8 T cell priming by B lymphocytes is CD4 help dependent
Authors: Castiglioni Paola , Gerloni Mara , Cortez‐Gonzalez Xochitl , Zanetti Maurizio 
Published: April 2005

AbstractWhile it is generally accepted that B lymphocytes can present antigen and activate CD4 T cells, priming of CD8 T cells by B lymphocytes remains controversial. Recently, we showed that mice injected with genetically programmed B lymphocytes generate antigen specific CD4 and CD8 T cell responses in vivo that could also be induced in mice lacking functional dendritic cells. To gain further insights into the requirements for T cell priming by antigen‐presenting B lymphocytes, in vitro experiments were performed using ovalbumin (OVA) and OVA‐specific TCR‐transgenic CD4 and CD8 T cells. We found that while B lymphocytes can directly prime CD4 T cells, the activation of CD8 T cells requires T cell help. Transfer experiments show that help can either be contact dependent or be mediated by soluble factors in the supernatants of activated OVA‐specific CD4 T cells. Furthermore, the effect of activated CD4 T cells can be replaced by soluble recombinant IL‐4. Collectively, the data show the existence of different requirements for priming of CD4 and CD8 T cells and point to the previously unappreciated fact that the induction of CD8 T cell responses by B lymphocytes requires T cell help.
IL‐4Rα signaling is important for CD8+ T cell cytotoxicity in the absence of CD4+ T cell help
Authors: Marsland Benjamin J. , Schmitz Nicole , Kopf Manfred 
Published: April 2005

AbstractCytotoxic CD8+ T cells are key mediators of viral clearance during primary infection through their production of IFN‐γ and lysis of virally infected cells. Comparatively, the cytokines IL‐4 and IL‐13 are typically associated with the development of Th2 immune responses against allergens and parasites, while their influence on cytotoxic CD8+ T cell responses is controversial. We have investigated the roles of IL‐4 and IL‐13 in the development of CD8+ T cell responses against influenza infection. We show that in the absence of either IL‐4 or IL‐13, CD8+ T cells proliferated and a normal secondary cytotoxic response developed in vitro. In striking contrast, the absence of IL‐4Rα resulted in impaired ex vivo proliferation and consequently no secondary CTL activity, whereas the in vivo response appeared normal. We show that the presence of CD4+ T cell help, or the addition of exogenous IL‐2 in vitro, restored the response. Taken together, this work reveals previously unrecognized in vivo redundancies between IL‐4, IL‐13 and IL‐2 during immune responses against influenza virus.
Dual regulation of BCR‐mediated growth inhibition signaling by CD72
Authors: Baba Takeshi , Fusaki Noemi , Aoyama Akitoshi , Li Daniel H. , Okamura Ross M. , Parnes Jane R. , Hozumi Nobumichi 
Published: April 2005

AbstractCD72 has been reported to regulate BCR‐mediated signals both positively and negatively. SHP‐1 and Grb2 bind, respectively, to ITIM1 and ITIM2 of CD72. We generated transformed B cell lines with an immature phenotype following J2 virus infection of splenocytes from CD72–/– and wild‐type (Wt) mice. The transformed lines were infected with retroviral vectors carrying Tyr (Y) to Phe (F) substitutions in the ITIM sequences (ITIM1 mutated: Y7/F; ITIM2 mutated: Y39/F; and both ITIM mutated: Y7,39/F). Cross‐linking of the BCR induced growth inhibition in transfectants expressing Wt CD72, but this response was less sensitive in transfectants with Y7,39/F. The Y7/F transfectants demonstrated the least sensitive response. We were not able to obtain transfectants with Y39/F, suggesting that CD72 associated with SHP‐1, but not with Grb2, delivers a strong negative signal. Pre‐ligation of CD72, which induces dephosphorylation of the molecule, partially rescued the Wt transfectants from growth inhibition, leading to a growth response profile similar to that of Y7,39/F transfectants. These results suggest that ITIM1/SHP‐1 delivers a very strong negative signal that is down‐modulated by signals through ITIM2/Grb2, leading to delivery of an attenuated negative signal. Thus, pre‐ligation of CD72 results in the manifestation of an ostensible positive signal.
Limited correlation between human thymus and blood NKT cell content revealed by an ontogeny study of paired tissue samples
Authors: Berzins Stuart P. , Cochrane Andrew D. , Pellicci Daniel G. , Smyth Mark J. , Godfrey Dale I. 
Published: April 2005

AbstractNKT cells are a CD1d‐restricted T cell subset with strong immunoregulatory properties. Human NKT deficiencies are associated with autoimmune diseases such as type 1 diabetes and several types of cancer, yet there is little understanding of how the human NKT cell pool develops or is maintained. In this study, we present the first detailed analysis of human NKT cells from donor‐matched postnatal thymus and blood samples. In mice, NKT cells are a thymus‐dependent population that migrates to the periphery at an immature stage. Our data show that human NKT cells also undergo early stages of development in the thymus, forming a CD4+CD161–/low population that predominates neonatal thymic and blood NKT cell pools. CD4– and CD161+ NKT cells accumulate with age in the blood, but not thymus, to the point that they dominate the NKT cell compartment in adult blood. This is consistent with the post‐thymic maturation of NKT cells exported from the thymus at the putatively immature CD4+CD161–/low stage. Interestingly, while thymus and peripheral NKT cell frequencies vary widely between patients and are relatively stable between age groups, there is no clear relationship between the NKT cell frequency in thymus and blood.
Distinct in vivo dendritic cell activation by live versus killed Listeria monocytogenes
Authors: Muraille Eric , Giannino Rielle , Guirnalda Patrick , Leiner Ingrid , Jung Steffen , Pamer Eric G. , Lauvau Gregoire 
Published: April 2005

AbstractImmunization of mice with live or heat‐killed Listeria monocytogenes (HKLM) efficiently primes pathogen‐specific CD8+ T cells. T lymphocytes primed by HKLM, however, undergo attenuated proliferation and do not fully differentiate. Thus, only infection with live bacteria induces long‐term, CD8+ T cell‐mediated protective immunity. In this study we demonstrate that live and heat‐killed bacteria, while both associating with Mac‐3+CD11bhi cells, localize to distinct splenic areas following intravenous inoculation. While HKLM localize to the marginal zone and the splenic red pulp, live L. monocytogenes are carried to the T cell zone of splenic white pulp. Despite these differences, in vivo depletion of CD11c‐expressing cells prevents priming of naive T cells by either HKLM or live L. monocytogenes. Analysis of CD11chi dendritic cells (DC) reveals that infection with live L. monocytogenes induces higher levels of CD40, CD80 and CD86 expression than immunization with HKLM. Our results suggest that CD8+ T cell priming following HKLM immunization or live infection is mediated by DC and that the disparate outcomes of priming can be attributed to suboptimal conditioning of DC in the absence of live, cytosol‐invasive bacteria.
Heterobimetallic Systems Containing Organometallic and Classical Coordination Sites: Effects of Subtle Changes in the Werner‐Type Site
Authors: Sheng Tianlu , Dechert Sebastian , Stückl A. Claudia , Meyer Franc 
Published: April 2005

AbstractSeveral highly unsymmetrical heterodinuclear Mn/Zn complexes are reported, in which an organometallic CpMn‐(CO)2 fragment and a classical Werner‐type zinc coordination unit are arranged in close proximity by means of a bridging pyrazolate. Ligand scaffolds differing in the chelate size of the tripodal tetradentate {N4} binding site, and different coligands for zinc are employed. Both the zinc‐devoid precursor compounds and the bimetallic complexes with zinc(II) nested in the tris(pyridylalkyl)amine type {N4} compartment have been characterized by X‐ray crystallography. Structural and spectroscopic features as well as the redox potentials of the MnI/MnII couple indicate slight effects of the redox‐inactive Werner‐type subunit on the properties of the organometallic site. Oxidation is highly localized at the organometallic manganese site, as is evidenced by IR and EPR spectroscopy and supported by DFT calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Effect of Conformation and Combination of 1,3‐Bis(4‐pyridylthio)propan‐2‐one upon Coordination Architectures: Syntheses, Characterizations and Properties
Authors: Wu Benlai , Yuan Daqiang , Jiang Feilong , Han Lei , Lou Benyong , Liu Caiping , Hong Maochun 
Published: April 2005

AbstractSelf‐assemblies of the conformationally labile ditopic ligand 1,3‐bis(4‐pyridylthio)propan‐2‐one (L) with square‐planer nodes CoII, NiII and with linear nodes AgI have afforded three new coordination polymers, {[Ni(L)2Cl2]}∞ (1), {[Co(L)2‐(SCN)2]·(DMF)2}∞ (2) and {[AgL]NO3}∞ (3), respectively. Structural analyses of these polymers and conformational analyses of L have revealed that metal‐assisted conformational selectivity and unique combinations of conformational isomers of L around the metal nodes probably play the key role in determining the structural topologies. In 1, a C2 symmetric array of two sorts of conformational isomers of L around NiII centers results in a 3D interpenetrating framework, while in 2 a combination of two types of conformational isomers of L around the inversion center CoII provides a 3D interpenetrating architecture of CdSO4‐like topology. In 3, L presents only a typical conformation, with higher steric energy, that links linear nodes AgI, leading to a 1D U‐like chain. The magnetic properties of 1 and 2, as well as the interesting fluorescent properties of 3, have also been investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis, Structure, Coordination Expansion and Theoretical Modelling of Dichlorobis(phenoxo) Titanium(IV) Complexes
Authors: Nielson Alastair J. , Shen Chaohong , Schwerdtfeger Peter , Waters Joyce M. 
Published: April 2005

AbstractThermalisation of TiCl4 and two equivalents of a phenol in toluene is found to be the best preparative method for quantitative yields of a variety of dichlorobis(phenoxo) complexes. [TiCl2(OC6H4CMe3‐4)2] (1) is monomeric in benzene, a phenoxo‐bridged dimer in the solid state and undergoes coordination expansion with 4,4'‐dimethyl‐2,2′‐bipyridine (dmbipy) to give [TiCl2(OC6H4CMe3‐4)2(dmbipy)] (2). Also monomeric are [TiCl2(OC6H2Me3‐2,4,6)2] (3) and [TiCl2(OC6H3iPr2‐2,6)2] (5) which expand their coordination with dmbipy to give [TiCl2(OC6H2Me3‐2,4,6)2(dmbipy)] (4) and [TiCl2(OC6H3iPr2‐2,6)2(dmbipy)] (6). In contrast [TiCl2(OC6H2{CMe3}2‐2,6‐Me‐4)2] (7) is only partially formed by the thermolysis reaction and does not coordinatively expand with dmbipy. [TiCl2(OC6H3Me2‐2,4)2] (8) is monomeric in benzene and reacts to form [TiCl2(OC6H3Me2‐2,4)2(dmbipy)] (9). [TiCl2(OC6H3{CMe3}2‐2,4)2] (10) forms along with the tri‐phenoxo complex [TiCl{OC6H3(CMe3)2‐2,4}3]. [TiCl2(OC6H3CMe3‐2‐Me‐6)2] (11) is monomeric in benzene and forms [TiCl2(OC6H3CMe3‐2‐Me‐6)2(dmbipy)] (12). 2‐Phenylphenol and 1‐napthol form [TiCl2(OC6H4Ph‐2)2] (13) and [TiCl2(OC10H9)2] (14) which are monomeric in benzene. DFT calculations give structural parameters for monomeric [TiCl2(OC6H5)2] (15) in good agreement with the X‐ray data for [TiCl2(OC6H3Me2‐2,6)2]. Each oxygen of the phenoxo ligand in 15 acts essentially as a 2π donor to titanium and there is substantial pπ(O)‐pπ*(C=C) backbonding with the phenyl ring, which is absent in [TiCl2(OCH3)2] (16). The global minimum for the dimer [(TiCl2{OC6H5}{μ‐OC6H5})2] is in almost perfect agreement with the crystal structure obtained for [(TiCl2{OC6H5}{μ‐OC6H5})2] or [(TiCl2{OC6H4CMe3‐4}{μ‐OC6H4CMe3‐4})2] (1). The dimerisation energy for 15 is–26.2 kJ·mol–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Luminescent Iridium(III)‐Terpyridine Complexes – Interplay of Ligand Centred and Charge Transfer States
Authors: Flamigni Lucia , Ventura Barbara , Barigelletti Francesco , Baranoff Etienne , Collin Jean‐Paul , Sauvage Jean‐Pierre 
Published: April 2005

AbstractElectrochemical properties, ground state absorption spectra, luminescence spectra and lifetimes (at room temperature and 77 K) as well as transient absorption spectra are reported herein for newly synthesized iridium(III) complexes in which benzamide units are appended to the coordinated terpyridine fragments. The nature of the luminescent excited states (Φ < 2 × 10–3 and τ in the microsecond range, in air‐equilibrated acetonitrile at 298 K) is discussed with regards to the ligand‐centred (3LC) or charge transfer (3CT) nature. At room temperature, the excited state, a predominantly ligand‐centred triplet (3LC) for the iridium(III) terpyridine compounds, is switched for the benzamide‐containing complexes to a charge transfer state (3CT). Intense absorption in the visible range, high energy content, long excited states lifetimes at 298 and 77 K and good luminescence yields make these complexes very promising as photosensitisers (P). The CT nature of the excited states of the benzamide‐containing complexes makes them ideal components for the construction of rigid, linear arrays of the Donor‐P‐Acceptor type for charge separation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Platinum Complexes with Only One Purine Ligand (Guanine, Deoxyguanine, or Adenine) Flanked by Two cis‐NH(CH3) Groups – Informative Models for Assessing the Interaction of Purine C6 Substituents with cis‐Amines
Authors: Carlone Maria , Marzilli Luigi G. , Natile Giovanni 
Published: April 2005

Abstractsyn‐(R,S)‐Me3dienPtL complexes (Me3dien = N,N',N‐trimethyldiethylenetriamine; L = a guanine, a 6‐deoxyguanine, or an adenine derivative) represent useful models for assessing the influence of the purine C6 substituent on the rate of rotation about the Pt–N7 bond. Because of the unsymmetric nature of the syn‐(R,S)‐Me3dien carrier ligand with respect to the coordination plane (all N–Me groups on one side of this plane), two rotamers are possible; they are defined as endo or exo for the six‐membered ring of the purine on the same or opposite side of the coordination plane as the N–Me groups, respectively. The derivatives of guanine (Pen), 6‐deoxyguanine (deoxy‐Pen), and adenine (MeA) used are distinguished by their C6 substituent (O, H, or NH2, respectively). At ambient temperature the rate of rotation of the purine about the Pt–N7 bond is slow on the NMR time scale for all three complexes. However, for Pen and deoxy‐Pen, an increase of the temperature from 293 to 353 K led to coalescence of the 1H NMR signals, indicating fast interconversion between rotamers and allowing evaluation of the rate constants and activation parameters (ΔH≠ and ΔS≠) for rotation. In contrast, for MeA raising the temperature to 353 K caused only a very slight broadening of the NMR signals, thus precluding a kinetic analysis of this complex by NMR methods. The rate of interconversion between the rotamers was comparable for the Pen and deoxy‐Pen complexes, notwithstanding the greater bulk of the C6 substituent in the Pen complex. On the other hand, the far slower rate of rotation for MeA, as compared to Pen, cannot be explained solely on the basis of C6 substituent bulk. Activation parameters for rotation (average values for the two rotamers: ΔH≠ = 57 ± 4 and 108 ± 3 kJ·mol–1, ΔS≠ = –18 ± 11 and 170 ± 11 J·K–1·mol–1 for Pen and deoxy‐Pen, respectively) suggest a plausible explanation for the observed trend. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Tapes of Cyclic Water Tetramers in the Double‐Helical Complex[Cd2(bpa)2Cl4]·6 H2O
Authors: Ye Bao‐Hui , Sun Ai‐Ping , Wu Tong‐Fei , Weng Yan‐Qin , Chen Xiao‐Ming 
Published: April 2005

AbstractThe new complex [Cd2(bpa)2Cl4]·6 H2O [bpa = N,N'‐bis(picolinamide)azine] has been synthesized in which each bpa ligand is twisted into a spiral‐like conformation and the two CdII ions are ligated by two bpa ligands to form a double‐stranded binuclear helicate. Unprecedented water chains featuring cyclic water tetramers composed of three independent water molecules are trapped by [Cd2(bpa)2Cl4] double helicates by hydrogen bonds. The binuclear chiral helicates are interlinked into homochiral layers by hydrogen bonds with the water tapes. The layers are alternately stacked in a heterochiral fashion to yield the final racemic structure. The complex shows an endotherm at 65.7 °C in the DSC due to loss of water molecules, giving an enthalpy value of 47 kJ mol–1 per water molecule. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Si‐, Ge‐, and Sn‐Centered Free Radicals: From Phantom Species to Grams‐Order‐Scale Materials (Eur. J. Inorg. Chem. 7/2005)
Authors: Lee Vladimir Ya. , Sekiguchi Akira 
Published: April 2005

AbstractThe cover picture shows the crystal structures of free radicals of the type (tBu2MeSi)3E· (E = Si, Ge, Sn) representing the first stable tricoordinate acyclic radicals of the heavier group 14 elements. All of these radicals have a perfect trigonal‐planar geometry, being truly π radicals, both in the crystalline form and in solution, accommodating an odd‐electron on the pz(E) orbitals. The synthesis of such stable radicals has been achieved nearly a century after the historical discovery of the first free radical species, triphenylmethyl Ph3C· by Gomberg in 1900. The recent developments in the field of stable Si‐, Ge‐, and Sn‐centered free radicals include the synthesis and physico‐chemical characterization of the neutral (cyclic and acyclic radicals) and charged (anion radicals of heavy carbene analogues, heavy alkene analogues and heavy alkyne analogues) compounds. The details of this chemistry are described and discussed in the Microreview by V. Ya. Lee and A. Sekiguchi on p. 1209 ff.
Exploring the role of topography in small channel erosion
Authors: Santisteban L. M. De , Casalí J. , López J. J. , Giráldez J. V. , Poesen J. , Nachtergaele J. 
Published: April 2005

AbstractErosion caused by concentrated flows in agricultural areas is responsible for important soil losses, and rapid sediment transfer through the channel network. The main factors controlling concentrated flow erosion rates include the erodibility of soil materials, soil use and management, climate and watershed topography. In this paper, two topographic indices, closely related to mathematical expressions suggested by different authors, are used to characterize the influence of watershed topography on gully erosion. The AS1 index is defined as the product of the watershed area and the partial area‐weighted average slope. The AS2 index is similar to the AS1 but uses the swale slope as the weighting factor. Formally, AS2 is the product of the watershed area and the length‐weighted average swale slope. From studies made using different ephemeral gully erosion databases, it is shown that a high correlation consistently exists between the topographic indices and the volume of eroded soil. The resulting relationships are therefore useful to assess soil losses from gully erosion, to identify the most susceptible watersheds within large areas, and to compare the susceptibility to gully erosion among different catchments. This information is also important in studying the response of natural drainage network systems to different rainfall inputs. Copyright © 2005 John Wiley & Sons, Ltd.
Modelling the effect of waves, weathering and beach development on shore platform development
Authors: Trenhaile A. S. 
Published: April 2005

AbstractA mathematical model was used to study shore platform development. Mechanical wave erosion was dependent on such variables as tidal range, wave height and period, breaker height and depth, breaker type, surf zone width and bottom roughness, submarine gradient, rock resistance and the elevational frequency of wave action within the intertidal zone. Also included were the effects of sand and pebble accumulation, cliff height and debris mobility, and downwearing associated with tidal wetting and drying. The occurrence, location and thickness of beaches often depended on initially quite minor variations in platform morphology, but owing to their abrasive or protective effect on underlying rock surfaces, they were able to produce marked differences in platform morphology. Generalizations are difficult, but the model suggests that platform gradient increases with tidal range. Platform width also increases with tidal range with slow downwearing but it decreases with fast downwearing. Platform gradient decreases and width increases with wave energy, and decreasing rock resistance and platform roughness. With low tidal range, platform gradient is generally lower and platform width greater with beaches of fine sand than with gravel, but the relationship is more variable with a high tidal range. Platform width increases and platform gradient decreases with the rate of downwearing on bare surfaces, particularly in low tidal range environments, but the pattern is less clear on beach‐covered platforms. Platforms with large amounts of beach sediment tend to be narrower and steeper than bare platform surfaces. Platform gradient increases and platform width decreases with increasing cliff height and with decreasing cliff debris mobility. Copyright © 2005 John Wiley & Sons, Ltd.
Blanket peat erosion and sediment yield in an upland reservoir catchment in the southern Pennines, UK
Authors: Yeloff D. E. , Labadz J. C. , Hunt C. O. , Higgitt D. L. , Foster I. D. L. 
Published: April 2005

AbstractThis paper investigates temporal variations in fluxes of peat and other sediment in the catchment of March Haigh Reservoir, West Yorkshire. Long‐term estimates of sediment yield were derived from a study of reservoir sediments. Magnetic properties were used to correlate ten cores to a master profile dated using 210Pb and 137Cs. A 14C date suggests that most of the organic component of the sediment is allochthonous and derived from peat eroded from the catchment. Organic sediment yields suggest low catchment erosion rates between 1838 and 1963. Blanket peat erosion increased significantly after 1963, and peaked between 1976 and 1984. Estimates of total sediment yield range between 2 and 28 t km−2 a−1. These yields are significantly lower than those from some previous studies examining reservoir sedimentation in other blanket peat‐covered catchments. The low yield estimates may be due to relatively low rates of erosion in the basin, but may also be partly explained by maintenance of silt traps during the early life of the reservoir and removal of sediment by scouring. Sedimentation within the reservoir is spatially variable, and bathymetry and sediment source appear to be the dominant controls on sedimentation patterns within the reservoir. Copyright © 2005 John Wiley & Sons, Ltd.
Vortex shedding from a square cylinder in presence of a moving wall
Authors: Bhattacharyya S. , Maiti D. K. 
Published: April 2005

AbstractA numerical study on the flow past a square cylinder placed parallel to a wall, which is moving at the speed of the far field has been made. Flow has been investigated in the laminar Reynolds number (based on the cylinder length) range. We have studied the flow field for different values of the cylinder to wall separation length. The governing unsteady Navier–Stokes equations are discretized through the finite volume method on a staggered grid system. A SIMPLE type of algorithm has been used to compute the discretized equations iteratively. A shear layer of negative vortex generates along the surface of the wall, which influences the vortex shedding behind the cylinder. The flow‐field is distinct from the flow in presence of a stationary wall. An alternate vortex shedding occurs for all values of gap height in the unsteady regime of the flow. The strong positive vortex pushes the negative vortex upwards in the wake. The gap flow in the undersurface of the cylinder is strong and the velocity profile overshoots. The cylinder experiences a downward force for certain values of the Reynolds number and gap height. The drag and lift are higher at lower values of the Reynolds number. Copyright © 2005 John Wiley & Sons, Ltd.