bluuebunny/crossref_metadata_2025_split huggingface dataset:
Goα labels ON bipolar cells in the tiger salamander retina
Authors: Zhang Jian , Wu Samuel M. 
Published: April 2003

AbstractBy using double‐label immunocytochemistry and confocal microscopy, we studied rod and cone synaptic contacts, photoreceptor‐bipolar cell convergence, and patterns of axon terminal ramification of ON bipolar cells in the tiger salamander retina. An antibody to recoverin, a calcium‐binding protein found in photoreceptors and other retinal neurons in various vertebrates, differentially labeled rods and cones by lightly staining rod cell bodies, axons, and synaptic pedicles and heavily staining cone cell bodies and pedicles. An antibody to Goα labeled most ON bipolar cells, with axon terminals ramified mainly in strata 6–9 and a minor band in stratum 3 of the inner plexiform layer (IPL). Stratum 10 of the IPL was Goα negative, and previous studies showed that axon terminals of rod‐dominated ON bipolar cells are monostratified in that stratum. The axonal morphology of Goα‐positive cells resembled that of the cone‐dominated (DBCC) or mixed rod and cone ON (DBCM) bipolar cells. The Goα‐positive dendritic processes made close contact with all cone pedicles and superficial contact with some rod pedicles, consistent with the idea that Goα subunits are present in DBCCs and DBCMs. The size and density of these cells were analyzed, and their spatial distributions were determined. To our knowledge, this is the first study to characterize photoreceptor inputs and axon terminal morphology of a population of ON bipolar cell with the use of a Goα antibody as an immunomarker in the salamander retina. J. Comp. Neurol. 461:276–289, 2003. © 2003 Wiley‐Liss, Inc.
CD55/decay accelerating factor is part of the lipopolysaccharide‐induced receptor complex
Authors: Heine Holger , El‐Samalouti Volker T. , Nötzel Corinna , Pfeiffer Alexandra , Lentschat Arnd , Kusumoto Shoichi , Schmitz Gerd , Hamann Lutz , Ulmer Artur J. 
Published: April 2003

AbstractRecently, we described an 80‐kDa lipopolysaccharide (LPS)‐binding membrane protein to be identical to CD55 [decay accelerating factor (DAF)]. Here, we demonstrate that CD55 is able to contribute to lipopolysaccharide (LPS) signaling. Transfection of Chinese hamster ovary (CHO) cells with human CD55 resulted in a translocation of NF‐κB after stimulation with LPS as well as with free lipid A. In addition, interaction of lipid A and CD55 was shown by co‐immuno‐precipitation of these molecules from CHO‐CD55 cells after incubation with lipid A and anti‐lipid A monoclonal antibody, as well as by fluorescence resonance energy transfer (FRET) analysis in human monocytes. The comparison of LPS‐induced signaling pathways in CHO‐CD55 and CHO‐CD14 cells revealed that p38, JNK and ERK MAP kinases are activated upon LPS stimulation in both cell lines, and that the activation by LPS can be blocked at the level of Toll‐like receptor 4. Finally, through FRET analysis we could demonstrate LPS‐induced clustering of CD55 and CD11/CD18 in human monocytes. Our results imply a new functional role of CD55 as a member of a multimeric LPS receptor complex.
Stable expression of MHC class I heavy chain/HLA‐DO complexes at the plasma membrane
Authors: van Lith Marcel , van Ham Marieke , Neefjes Jacques 
Published: April 2003

AbstractMajor histocompatibility complex (MHC) class I and II molecules present antigenic fragments to the immune system. MHC‐like chaperones, like HLA‐DM, HLA‐DO and tapasin support peptide loading. HLA class I heavy chains require association with β2‐microglobulin and peptide for endoplasmic reticulum (ER) exit. Likewise, HLA‐DO is only able to leave the ER by association to DM. Here we show that HLA‐DO and free MHC class I heavy chains associate into a stable complex early during biosynthesis and are expressed at the plasma membrane as a complex. These DO/heavy chain complexes are found on DO‐transfected cells and on low amounts on human B cells.
Fibrinogen‐CD11b/CD18 interaction activates the NF‐κB pathway and delays apoptosis in human neutrophils
Authors: Rubel Carolina , Gómez Sonia , Fernández Gabriela C. , Isturiz Martín A. , Caamaño Jorge , Palermo Marina S. 
Published: April 2003

AbstractThe regulation of neutrophil half‐life by members of the coagulation cascade is critical for the resolution of the inflammatory response. We have demonstrated that soluble fibrinogen (sFbg) delays human neutrophil (PMN) apoptosis through a mechanism that involves CD11b interactions, and phosphorylation of focal adhesion kinase (FAK) and extracellular signal‐regulated kinase 1/2 (ERK1/2).Since NF‐κB is a key element in the regulation of apoptotic mechanisms in several immune cells, we investigated whether NF‐κB is involved in the control of PMN survival by sFbg. We showthat sFbg triggers inhibitor protein κB (IκB‐α) degradation and NF‐κB activation. Furthermore, pharmacological inhibition of NF‐κB abrogates sFbg effects on apoptosis. In addition, specific inhibition of MAPK ERK1/2 significantly reduces NF‐κB translocation by sFbg, suggesting a relationship between ERK1/2 and NF‐κB activation. Similar results are obtained when granulocytic‐differentiated HL‐60 cells are treated with sFbg, making this model highly attractive for integrin‐induced gene expression studies. It can be concluded that NF‐κB participates in the prevention of apoptosis induced by sFbg with the participation of MAPK ERK1/2. These results shed light on the molecular mechanisms that control human granulocyte apoptosis, and suggest that NF‐κB regulation may be of benefit for the resolution of the inflammatory response.
T cell adhesion lowers the threshold for antigen detection
Authors: Randriamampita Clotilde , Boulla Geneviève , Revy Patrick , Lemaitre Fabrice , Trautmann Alain 
Published: April 2003

AbstractAntigen detection and initiation of TCR signaling only occur, under physiological conditions, when T cells are adherent, and not in suspension. We show here that T cell adhesion causes an increase in the Ca2+ content of intracellular stores and of the amount of phosphatidylinositol 4,5‐bisphosphate in the plasma membrane, and enhances TCR‐induced Ca2+ signaling. This priming can be observed in freshly isolated T cells, in activated T cells, and in some T cell lines. Stimulation of T cells by specific monomeric MHC‐peptide complexes only triggers Ca2+ responses after T cell adhesion. This solves a controversial issue concerning the minimum valency of activatory TCR ligands. Adhesion‐induced T cell priming not only occurs upon binding to artificial substrates such as immobilized ligands, but also upon interaction with dendritic cells. Thus, this phenomenon is likely to contribute to the high sensitivity of antigen detection by T cells in secondary lymphoid organs.
Chemokines integrate JAK/STAT and G‐protein pathways during chemotaxis and calcium flux responses
Authors: Soriano Silvia F. , Serrano Antonio , Hernanz‐Falcón Patricia , de Ana Ana Martín , Monterrubio María , Martínez‐A Carlos , Rodríguez‐Frade J. Miguel , Mellado Mario 
Published: April 2003

AbstractThe JAK/STAT (Janus kinase / signaling transducer and activator of transcription) signaling pathway is implicated in converting stationary epithelial cells to migratory cells. In mammals, migratory responses are activated by chemoattractant proteins, including chemokines. We found that by binding to seven‐transmembrane G‐protein‐coupled receptors, chemokines activate the JAK/STAT pathwayto trigger chemotactic responses. We show that chemokine‐mediated JAK/STAT activation is critical for G‐protein induction and for phospholipase C‐β dependent Ca2+ flux; in addition, pharmacological inhibition of JAK or mutation of the JAK kinase domain causes defects in both responses. Furthermore, Gαi association with the receptor is dependent on JAK activation, andthe chemokine‐mediated Ca2+ flux that requires phospholipase C‐β activity takes place downstream of JAK kinases. The chemokines thus employ a mechanism that links heterologous signaling pathways — G proteins and tyrosine kinases — in a network that may be essential for mediating their pleiotropic responses.
Synthesis of C1‐Symmetric Tripod Ligands Containing a P,P,N Donor Set − η2‐Coordination in d8‐Metal Complexes
Authors: Faissner Ralf , Huttner Gottfried , Kaifer Elisabeth , Rutsch Peter 
Published: April 2003

AbstractTripod ligands RC(CH2X)(CH2Y)(CH2Z) (X, Y, Z = NR2, PR2) are accessible from α,β‐unsaturated esters R(=CH2)COOR′. The key steps in this synthetic approach are Michael additions of amines and phosphanes to produce RCH(COOR′)(CH2X) (X = NR2, PR2) (2 and 3), followed by hydroxymethylation with paraformaldehyde to result in RC(COOR′)(CH2OH)(CH2X) (X = NR2) (4). Standard transformations of this C1‐symmetric precursor allow for the synthesis of tripod ligands such as PhC(CH2pz)(CH2PPh2)(CH2PMes) (11). Coordination of these ligands with d8‐metal ions [nickel(II), palladium(II), rhodium(I)] results in square‐planar complexes with the chelate cycles in half‐chair, twist‐boat or boat conformations, depending on the specific substitution pattern. Coordination through two phosphane donors with the nitrogen donor acting as a dangling arm is generally preferred throughout. Detail preparative procedures and complete characterisation by analytical methods, including X‐ray analysis of the coordination compounds, are given. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Effect of buffer, electric field, and separation time on detection of aptamer‐ligand complexes for affinity probe capillary electrophoresis
Authors: Buchanan Danielle D. , Jameson Emily E. , Perlette Jon , Malik Abdul , Kennedy Robert T. 
Published: April 2003

AbstractThe separation and detection of complexes of aptamers and protein targets by capillary electrophoresis (CE) with laser‐induced fluorescence was examined. Aptamer‐thrombin and aptamer‐immunoglobulin E (IgE) were used as model systems. Phosphate, 3‐(N‐morpholino)propanesulfonic acid with phosphate, and tris(hydroxyamino)methane‐glycine‐potassium (TGK) buffer at pH 8.4 were tested as electrophoresis media. Buffer had a large effect with TGK providing the most stable complexes for both protein‐aptamer complexes. Conditions that suppressed electroosmotic flow, such as addition of hydroxypropylmethylcellulose to the media or modification of the capillary inner wall with polyacrylamide, were found to prevent detection of complexes. The effect of separation time and electric field were evaluated by monitoring complexes with electric field varied from 150–2850 V/cm and effective column lengths of 3.5 and 7.0 cm. As expected, shorter times on the column greatly increased peak heights for the complexes due to a combination of less dilution by diffusion and less dissociation on the column. High fields were found to have a detrimental effect on detection of complexes. It is concluded that the best conditions for detection of noncovalent complexes involve use of the minimal column length and electric field necessary to achieve separation. The results will be of interest in developing affinity probe CE assays wherein aptamers are used as affinity ligands.
Aragonite Formation in the Chiton (Mollusca) Girdle
Authors: Treves Keren , Traub Wolfie , Weiner Steve , Addadi Lia 
Published: April 2003

AbstractIn the chitons (Polyplacophora, Mollusca), the body is not entirely protected by the shell. Mineralized spicules or scales often, but not always, decorate the exposed part of the girdle. Here, we report a study on the composition and ultrastructural organization of these mineralized skeletal parts in four different chiton species. In all specimens, the mineral component (97–98 wt‐%) is aragonite, and the organic matrix (2–3 wt‐%) consists of highly glycosylated proteins. X‐Ray diffraction and scanning electron microscopy show that the organic matrix fibers are aligned, morphologically and crystallographically, with the prismatic aragonite crystals. Matrix and mineral are thus clearly related. The matrix–mineral composite bundles are, however, assembled in the various skeletal parts examined with widely different degrees of alignment and order. In the same organism, the crystals are aligned within a range of ±15° in one type of spicule, while they are randomly oriented in another type. The wide heterogeneity in shape, density, and ultrastructure suggests that the girdle mineralized tissues do not fulfill a fundamental role necessary for the survival of the organism. This, together with the lack of chitin in the organic matrix, supports the hypothesis that they evolved separately from the other chiton mineralized tissues, namely the shell plates and teeth.
Who's controlling whom? Infant contributions to maternal play behavior
Authors: Dixon Wallace E. , Hull Smith P. 
Published: April 2003

AbstractBecause the way mothers play with their children may have significant impacts on children's social, cognitive, and linguistic development, researchers have become interested in potential predictors of maternal play. In the present study, 40 mother–infant dyads were followed from child age 5–20 months. Five‐month habituation rate and 13 and 20 month temperamental difficulty were found to be predictive of maternal play quality at 20 months. The most parsimonious theoretical model was one in which habituation was mediated by temperamental difficulty in predicting mother play. Consistent with prior speculation in the literature, these data support the possibility that mothers adjust some aspects of their play behaviors to fit their children's cognitive and temperamental capabilities. Copyright © 2003 John Wiley & Sons, Ltd.
Eddy currents and electrical surface charges
Authors: Baum Eckhard , Erb Otto 
Published: April 2003

AbstractIn eddy current calculations, the displacement current in the non‐conducting space surrounding the eddy current region is usually neglected. This assumption enforces that the electric charge density and the accompanying normal components of the eddy current density on the surface of the eddy current region must vanish.If the field exiting source currents are not accompanied by charges this assumption may yield acceptable results for the eddy current distribution. However, if the field exiting source currents are accompanied by charges, this assumption may lead to totally wrong results for the current distribution in the eddy current region. An example is given which makes plain this point.To obtain correct results it is not necessary to employ the full set of Maxwell's equations capable to describe wave propagation phenomena also outside the eddy current region. It is shown in the paper that by replacing the displacement current density in the field describing equations by a specifically chosen current density function makes it possible to determine eddy currents and surface charges within the quasi‐stationary calculation scheme for arbitrary field exciting source currents which may or may not be accompanied by charges. The solution obtained in this way is shown to be unique. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling of photonic bandgap devices by the leaky mode propagation method
Authors: Giorgio Agostino , Gina Perri Anna 
Published: April 2003

AbstractMain modelling approaches used for investigating the Photonic bandgap (PBG) devices are reviewed. In particular, the model based on Leaky Mode Propagation (LMP) method is described.A complete analysis of the propagation characteristics, including the determination of modal propagation constants, electromagnetic field harmonics and total field distribution, transmission and reflection coefficients, total forward and backward power flow in the structure, guided and radiated power, and total losses, can be carried out by a computer program based on the LMP approach.The numerical results have been validated by comparisons with those obtained by using other more complex and expensive models.The new model shows some significant advantages in terms of very low computational time, absence of any a priori theoretical assumptions and approximations, capability of simulating the actual physical behaviour of the device and fast determination of the bandgap position.Copyright © 2003 John Wiley & Sons, Ltd.
Multiresolution model of electromagnetic wave propagation in dispersive materials
Authors: Barba Ismael , Represa José , Fujii Masafumi , Hoefer Wolfgang J. R. 
Published: April 2003

AbstractA multiresolution time‐domain (MRTD) technique based on Haar wavelets has been applied to model the propagation of waves in dispersive materials, using a discretization of the convolution equation that governs the behaviour of the media. To validate the method, the reflection coefficient at the interface between air and several different linear dispersive media, as well as the propagation of a plane wave towards a non‐linear dispersive medium have been calculated and compared with other numerical techniques and theoretical results. Copyright © 2003 John Wiley & Sons, Ltd.
Thermodynamics of the Double Helix‐Coil Equilibrium in Tetramethylammonium Gellan: High‐Sensitivity Differential Scanning Calorimetry Data
Authors: Grinberg Valerij Ya. , Burova Tatiana V. , Grinberg Natalia V. , Mashkevich Alexander Ya. , Plashchina Irina G. , Usov Anatoly I. , Shusharina Nadezhda P. , Khokhlov Alexei R. , Navarini Luciano , Cesàro Attilio 
Published: April 2003

AbstractThe order–disorder conformational transition in the tetramethylammonium salt of gellan has been studied by high‐sensitivity differential scanning calorimetry as a function of concentration of the background electrolyte, Me4NCl (0.0025–0.5 M). The transition temperature and enthalpy increase with increasing salt concentration following a logarithmic relation. At the same time, there is a linear correlation between the transition enthalpy and temperature with a positive slope of 0.18 J g−1 K−1. According to Kirchhoff's law, the slope can be considered as a heat capacity increment of the transition. This value is much larger than that expected to arise from electrostatic effects. Thus, it has been suggested that the transition is accompanied by an increase in water accessibility to some less hydrophilic fragments of the primary structure of gellan buried in its ordered conformation. The transition has an λ‐like heat capacity profile and can be therefore defined as a second‐order phase transition. This assignment is in agreement with predictions of a matching model of the double helix‐coil transition. The model fits well to the integral transition curve at 0.5 M Me4NCl, assuming a cooperative length of gellan to be about eight repeating units. This value is close to the size of chain corresponding to the persistent length of gellan in the coil state. The cooperativity parameter in the matching model (σ = 0.62 ± 0.01) indicates a small contribution of the stacking effect into the cooperativity of the transition, while a larger contribution apparently originates from the loop factor. The free energy of transition at a reference temperature (273 K) is a logarithmic function of the concentration of the salt, ΔtG(Cs), as predicted by the counter condensation theory and the Poisson–Boltzmann (PB) model. The latter is preferable because of the low linear charge density parameter (ξ < 1) for the double helix of gellan. Analysis of the ΔtG(Cs) function in terms of the PB model showed that the linear charge density of gellan in the coil conformation needs to be higher than that estimated for the fully stretched chain.Correlation between the transition enthalpy and the transition temperature for the conformational order–disorder transition in the TMA gellan.magnified imageCorrelation between the transition enthalpy and the transition temperature for the conformational order–disorder transition in the TMA gellan.
Studies in ring opening polymerisation, 6. Tertiary base initiated polymerisation of 5‐phenyl‐1,3‐dioxolan‐2,4‐dione
Authors: Smith Ian Joseph , Tighe Brian John 
Published: April 2003

Abstract5‐Phenyl‐1,3‐dioxolan‐2,4‐dione (the anhydrocarboxylate derivative of mandelic acid) has been shown to undergo polymerisation in the presence of tertiary organic bases such as pyridine in a reaction that has somewhat unusual characteristics. Thus, although the reaction in nitrobenzene shows first‐order kinetic dependence on both monomer and pyridine over a reasonable concentration range, the pyridine is not consumed and does not appear to control the molecular weight of the resultant polymer. The most important factor in controlling molecular weight is the presence of adventitious moisture which enters into the polymerisation process producing poly‐α‐esters that are hydroxyl/carboxyl terminated. The rate of polymerisation increases progressively as pyridine is replaced by 2‐methylpyridine and 2,6‐dimethylpyridine but decreases dramatically when 2‐methoxypyridine is used, indicating the importance of the basicity of the attacking species. The results are interpreted in terms of the interaction of the basic nitrogen and the C‐4 ring carbonyl leading to the formation of a transient charge transfer complex which subsequently decomposes to form pyridine, carbon dioxide and the α‐lactone. The chain growth process involves the interaction of the α‐lactone with any nucleophiles present which control the molecular weight and nature of the end groups.
Polymerisation via macrozwitterions, 1. Ethyl and butyl cyanoacrylates polymerised by triethyl and triphenylphosphines
Authors: Johnston David Samuel , Pepper David Charles 
Published: April 2003

AbstractAnionic polymerisation of ethyl and butyl cyanoacrylates in THF initiated by triethyl and triphenylphosphines were followed by adiabatic calorimetry at temperatures between 20 and −95°C. The polymers showed UV absorptions characteristic of phosphonium and cyanoacrylate carbanion end groups, indicating that the growing chains were macrozwitterions. Monomer conversion was quantitative and of 1st order in both monomer and initiator. Other criteria of ‘living’ polymerisation were satisfied, e.g. molecular weights corresponded to one chain per initiator molecule, and indicated that monomer added subsequently was incorporated on to previously formed chains. Assuming the overall rate to be that of propagation yielded values of kp = 1 – 3 · 105 dm3 · mol−1 · s−1 at −78°C, with very low activation energies, i.e. 2,2 and 5,5 kJ · mol−1 for ECA and BCA, respectively. Of a range of inert salts only LiBr significantly reduced the rate of polymerisation.
On L1 decay problem for the dissipative wave equation
Authors: Ono Kosuke 
Published: April 2003

AbstractWe study the decay estimates of solutions to the Cauchy problem for the dissipative wave equation in one, two, and three dimensions. The representation formulas of the solutions provide the sharp decay rates on L1 norms and also Lp norms. Copyright © 2003 John Wiley & Sons, Ltd.
On a first‐order hyperbolic coagulation model
Authors: Ackleh Azmy S. , Deng Keng 
Published: April 2003

AbstractWe consider a first‐order hyperbolic initial–boundary value problem that models coagulation of particles. We establish a comparison principle and construct monotone sequences to show the existence and uniqueness of the solution. Copyright © 2003 John Wiley & Sons, Ltd.