bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bam32/DAPP1 Promotes B Cell Adhesion and Formation of Polarized Conjugates with T Cells
Authors: Al-Alwan Monther , Hou Sen , Zhang Ting-ting , Makondo Kennedy , Marshall Aaron J. 
Published: May 2010

Abstract
B cell Ag receptors function in both signaling activation of Ag-specific cells and in collecting specific Ag for presentation to T lymphocytes. Signaling via PI3K is required for BCR-mediated activation and Ag presentation functions; however, the relevant downstream targets of PI3K in B cells are incompletely defined. In this study, we have investigated the roles of the PI3K effector molecule Bam32/DAPP1 in BCR signaling and BCR-mediated Ag presentation functions. In mouse primary B cells, Bam32 was required for efficient activation of the GTPase Rac1 and downstream signaling to JNK, but not activation of BLNK, phospholipase C γ2, or calcium responses. Consistent with a role of this adaptor in Rac-mediated cytoskeletal rearrangement, Bam32 was required for BCR-induced cell adhesion and spreading responses on ICAM-1 or fibronectin-coated surfaces. The function of Bam32 in promoting Rac activation and adhesion required tyrosine 139, a known site of phosphorylation by Lyn kinase. After BCR crosslinking by Ag, Bam32-deficient B cells are able to carry out the initial steps of Ag endocytosis and processing, but show diminished ability to form Ag-specific conjugates with T cells and polarize F-actin at the B-T interface. As a result, Bam32-deficient B cells were unable to efficiently activate Ag-specific T cells. Together, these results indicate that Bam32 serves to integrate PI3K and Src kinase signaling to promote Rac-dependent B cell adhesive interactions important for Ag presentation function.
B Cell Receptor-Mediated Calcium Signaling Is Impaired in B Lymphocytes of Type Ia Patients with Common Variable Immunodeficiency
Authors: Foerster Christian , Voelxen Nadine , Rakhmanov Mirzokhid , Keller Baerbel , Gutenberger Sylvia , Goldacker Sigune , Thiel Jens , Feske Stefan , Peter Hans-Hartmut , Warnatz Klaus 
Published: May 2010

Abstract
Several lines of evidence have demonstrated B cell intrinsic activation defects in patients with common variable immunodeficiency (CVID). The rapid increase of intracellular free calcium concentrations after engagement of the BCR represents one crucial element in this activation process. The analysis of 53 patients with CVID for BCR-induced calcium flux identified a subgroup of patients with significantly reduced Ca2+ signals in primary B cells. This subgroup strongly corresponded to the class Ia of the Freiburg classification. Comparison at the level of defined B cell subpopulations revealed reduced Ca2+ signals in all mature B cell populations of patients with CVID class Ia when compared with healthy individuals and other groups of patients with CVID but not in circulating transitional B cells. BCR-induced Ca2+ responses were the lowest in CD21low B cells in patients as well as healthy donors, indicating an additional cell-specific mechanism inhibiting the Ca2+ flux. Although proximal BCR signaling events are unperturbed in patients’ B cells, including normal phospholipase Cγ2 phosphorylation and Ca2+ release from intracellular stores, Ca2+ influx from the extracellular space is significantly impaired. CD22, a negative regulator of calcium signals in B cells, is highly expressed on CD21low B cells from patients with CVID Ia and might be involved in the attenuated Ca2+ response of this B cell subpopulation. These data from patients with CVID suggest that a defect leading to impaired BCR-induced calcium signaling is associated with the expansion of CD21low B cells, hypogammaglobulinemia, autoimmune dysregulation, and lymphadenopathy.
Individual Variation in the Germline Ig Gene Repertoire Inferred from Variable Region Gene Rearrangements
Authors: Boyd Scott D. , Gaëta Bruno A. , Jackson Katherine J. , Fire Andrew Z. , Marshall Eleanor L. , Merker Jason D. , Maniar Jay M. , Zhang Lyndon N. , Sahaf Bita , Jones Carol D. , Simen Birgitte B. , Hanczaruk Bozena , Nguyen Khoa D. , Nadeau Kari C. , Egholm Michael , Miklos David B. , Zehnder James L. , Collins Andrew M. 
Published: May 2010

Abstract
Individual variation in the Ig germline gene repertoire leads to individual differences in the combinatorial diversity of the Ab repertoire, but the study of such variation has been problematic. The application of high-throughput DNA sequencing to the study of rearranged Ig genes now makes this possible. The sequencing of thousands of VDJ rearrangements from an individual, either from genomic DNA or expressed mRNA, should allow their germline IGHV, IGHD, and IGHJ repertoires to be inferred. In addition, where previously mere glimpses of diversity could be gained from sequencing studies, new large data sets should allow the rearrangement frequency of different genes and alleles to be seen with clarity. We analyzed the DNA of 108,210 human IgH chain rearrangements from 12 individuals and determined their individual IGH genotypes. The number of reportedly functional IGHV genes and allelic variants ranged from 45 to 60, principally because of variable levels of gene heterozygosity, and included 14 previously unreported IGHV polymorphisms. New polymorphisms of the IGHD3-16 and IGHJ6 genes were also seen. At heterozygous loci, remarkably different rearrangement frequencies were seen for the various IGHV alleles, and these frequencies were consistent between individuals. The specific alleles that make up an individual's Ig genotype may therefore be critical in shaping the combinatorial repertoire. The extent of genotypic variation between individuals is highlighted by an individual with aplastic anemia who appears to lack six contiguous IGHD genes on both chromosomes. These deletions significantly alter the potential expressed IGH repertoire, and possibly immune function, in this individual.
Cutting Edge: Lack of High Affinity Competition for Peptide in Polyclonal CD4+ Responses Unmasks IL-4 Production
Authors: Milner Joshua D. , Fazilleau Nicolas , McHeyzer-Williams Michael , Paul William 
Published: May 2010

Abstract
Priming of naive monoclonal CD4 T cells via weak agonsim permits GATA-3 transcription and Th2 differentiation. To test whether this process can occur in polyclonal naive populations, where a range of TCR affinities exists for any given Ag/MHC complex, we primed naive CD4 cells from 5CC7 Vβ3 transgenic mice, which have a fixed β-chain specific for pigeon cytochrome c peptide I-Ek. Priming populations de-pleted of higher affinity, moth cytochrome c pep-tide I-Ek tetramer-binding cells resulted in substantial IL-4 production that did not occur in the presence of higher affinity cells. TCRα-chain sequence analysis showed that clones that possessed TCR features associated with high affinity responses to pigeon cytochrome c made less IL-4 than clones that possessed fewer such motifs. These results indicate that cells bearing TCRs that are weakly stimulated by their cognate Ag preferentially adopt a Th2 phenotype when primed in the absence of competition from cells with higher affinity receptors.
Selective partial update and set‐membership improved proportionate normalized subband adaptive filter algorithms
Authors: Abadi Mohammad Shams Esfand 
Published: May 2010

AbstractIn this article, the concept of proportionate adaptation is extended to the selective partial update (SPU) and set‐membership (SM) normalized subband adaptive filters (NSAFs), and three proportionate normalized subband adaptive filter algorithms are established. The proposed algorithms are the improved proportionate NSAF (IPNSAF), the SPU improved proportionate NSAF (SPU‐IPNSAF), and the SM‐IPNSAF which are suitable for sparse system identification. When the impulse response of the echo path is sparse, the IPNSAF algorithm has faster convergence than NSAF. The performance of IPNSAF is also suitable for dispersive impulse responses. In SPU‐IPNSAF, the filter coefficients are partially updated rather than the entire filter at every adaptation which reduces the computational complexity of IPNSAF. The SM‐IPNSAF exhibits good performance with significant reduction in the overall computational complexity compared with the ordinary IPNSAF. The simulation results show good performance of the proposed algorithms. Copyright © 2010 John Wiley & Sons, Ltd.
Adaptive robust control of a class of nonlinear systems in semi‐strict feedback form with non‐uniformly detectable unmeasured internal states
Authors: Lu Lu , Yao Bin 
Published: May 2010

AbstractThis paper proposes a novel control method for a special class of nonlinear systems in semi‐strict feedback form. The main characteristic of this class of systems is that the unmeasured internal states are non‐uniformly detectable, which means that no observer for these states can be designed to make the observation error exponentially converge to zero. In view of this, a projection‐based adaptive robust control law is developed in this paper for this kind of system. This method uses a projection‐type adaptation algorithm for the estimation of both the unknown parameters and the internal states. Robust feedback term is synthesized to make the system robust to uncertain nonlinearities and disturbances. Although the estimation error for both the unknown parameters and the internal states may not converge to zero, the tracking error of the closed‐loop system is proved to converge to zero asymptotically if the system has only parametric uncertainties. Furthermore, it is theoretically proved that all the signals are bounded, and the control algorithm is robust to bounded disturbances and uncertain nonlinearities with guaranteed output tracking transient performance and steady‐state accuracy in general. The class of system considered here has wide engineering applications, and a practical example—control of mechanical systems with dynamic friction—is used as a case study. Simulation results are obtained to demonstrate the applicability of the proposed control methodology. Copyright © 2010 John Wiley & Sons, Ltd.
Novel N‐ethyl‐2‐styrylquinolinium iodides as sensitizers in the photoinitiated free‐radical polymerization of trimethylolopropane triacrylate. II
Authors: Kabatc Janina , Krzyżanowska Edyta , Jędrzejewska Beata , Pietrzak Marek , Pączkowski Jerzy 
Published: May 2010

AbstractResults of kinetic studies of two‐component photoinitiator systems used in the visible‐light photoinduced polymerization of 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol triacrylate are presented. Nine different styrylquinolinum dyes coupled with n‐butyltriphenylborate as a coinitiator have been used as photoinitiating systems. Reactive radicals that initiate the polymerization are formed by the well‐known mechanism of photoinduced electron transfer between dye cations acting as electron acceptors and borate anions acting as electron donors. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Water‐soluble copolymers. V. Synthesis of low molecular weight amphoteric polyacrylamide by foamed copolymerization
Authors: Peng Xiaohong , Tao Zhenghong , Peng Xiaochun 
Published: May 2010

AbstractAmphoteric polyacrylamide of acrylamide, acryloyloxyethyl trimethylammonium chloride, sodium acrylate, and acrylic acid was synthesized by foamed copolymerization. The effects of monomer concentration and composition, initiator concentration and composition, sodium bicarbonate and stabilizer content on the polymer intrinsic viscosity and monomer conversion were examined. The monomer conversion increased with increasing initiator concentration, sodium bicarbonate and stabilizer content. The polymer intrinsic viscosity decreased with increasing initiator concentration. The structure and low molecular weight of the amphoteric polymer were identified by fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC), respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Facile method for the synthesis of polystyrene–poly(ethylene glycol) block copolymers
Authors: Feng Libang , Gou Liuxiaohui , Yang Junliang , Luo Yajun , Wang Yulong 
Published: May 2010

AbstractA facile method for synthesis of polystyrene–poly(ethylene glycol) block copolymers under mild conditions, for instance, ambient temperature and atmospheric pressure, by the direct esterification condensation reaction was developed. The block copolymers were characterized with such techniques as Fourier transform infrared spectroscopy, 1H‐NMR, gel permeation chromatography, differential scanning calorimetry, and X‐ray diffraction. The results show that block copolymers with a yield of over 80% were successfully synthesized with this facile approach, and the resulting block copolymers exhibited both glass‐transition and melting endothermal signals and both amorphous and crystal phases as well; this indicated that the block copolymers had a microphase‐separated structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of quaternized carboxymethyl chitosan and its capacity to flocculate COD from printing wastewater
Authors: Cai Zhao‐Sheng , Yang Chun‐Sheng , Zhu Xue‐Mei 
Published: May 2010

AbstractA bioflocculant, quaternized carboxymethyl chitosan (QCMC), was developed by the quaternization of N,O‐carboxymethyl chitosan (N,O‐CMC) and characterized by FTIR, 1H‐NMR, GPC, and potentiometry. The efficiency of the removal of chemical oxygen demand (COD) in printing wastewater by this flocculant was further reported. Results indicated that the capacity of QCMC to remove the COD from tested wastewater was the best one among the investigated flocculants. The pH had great influence on this capacity and the suitable pH for QCMC to treat the tested wastewater was about 5.0. The utilization of aid‐flocculant, especially bentonite, could improve this capacity obviously, and the increase of mass ratio of bentonite to QCMC resulted in the increase of the capacities of complex flocculant to remove the COD from the tested wastewater. When the mass ratio of bentonite to QCMC was 40, pH of wastewater was 5.0 and amount of complex flocculant in the wastewater was from 2500 to 3142 mg L−1, the removal ratio of COD was more than 80%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The influence of montmorillonite on the anti‐reversion in the rubber–clay composites
Authors: Zhang Peng , Huang Guangsu , Wang Xiao'an , Nie Yijing , Qu Liangliang , Wen Gengsheng 
Published: May 2010

AbstractThe influence of organically modified montmorillonate (OMMT) on the curing reversion of natural rubber (NR) and polychloroprene rubber (CR) blend has been demonstrated in this article. Characteristics of the NR/CR/OMMT hybrid composite were undertaken by combining the cure kinetics, thermal stability, and the detection of phase morphology. Compared to the neat rubber blend, thermal gravity analysis has shown improved thermal stability results during degradation for the nanofiller filled ones. Differential scanning calorimetry study has offered cure kinetic results; among which blending with NR has lifted the cure activation temperature of CR low toward. Meanwhile, transmission electron microscopy has shown the intercalation and immobilization of OMMT in the CR phase formed a barrier to NR phase. In addition, to discover the reversion source, infrared spectroscopy has been applied to trace the oxygenic function units in the neat NR vulcanizate. All of the experimental results and related analysis has offered us the base to explain the improvement of the anti‐reversion of the rubber blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Microcellular foaming of polymethylmethacrylate in a batch supercritical CO2 process: Effect of microstructure on compression behavior
Authors: Reglero Ruiz Jose Antonio , Viot Philippe , Dumon Michel 
Published: May 2010

AbstractMicrocellular foaming of reinforced core/shell Polymethylmethacrylate (PMMA) was carried out by means of supercritical CO2 in a single‐step process. Samples were produced using a technique based on the saturation of the polymer under high pressure of CO2 (300 bars, 40°C), and cellular structure was controlled by varying the depressurization rate from 0.5 bar/s to 1.6 × 10−2 bar/s leading to cell sizes from 1 μm to 200 μm, and densities from 0.8 to 1.0 g/cm3. It was found that the key parameter to control cell size was depressurization rate, and larger depressurization rates generated bigger cell sizes. On the other hand, variation of the density of the samples was not so considerable. Low rate compression tests were carried out, analyzing the dependence of mechanical parameters such as elastic modulus, yield stress and densification strain with cell size. Moreover, the calculation of the energy absorbed for each sample is presented, showing an optimum of energy absorption up to 50% of deformation in the micrometer cellular range (here at a cell size of about 5 μm). To conclude, a brief comparison between neat PMMA and the core/shell reinforced PMMA has been carried out, analyzing the effect of the core/shell particles in the foaming behavior and mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Structural, mechanical and thermal studies of double‐molded isotactic polypropylene nanocomposites with multiwalled carbon nanotubes
Authors: Mina Md. Forhad , Haque Md. Akramul , Bhuiyan Md. Khairul Hassan , Gafur Md. Abdul , Tamba Yukihiro , Asano Tsutomu 
Published: May 2010

AbstractNanocomposites of isotactic polypropylene (iPP) and multiwalled carbon nanotubes (MWCNTs) with various contents of MWCNTs were fabricated by double molding techniques. X‐ray diffraction measurements reveal a development of α‐crystal with lamellar stacks having a long period of 150 Å in the neat iPP that increases to 165 Å in 2 wt % MWCNTs‐loaded composites, indicating that MWCNTs enhance crystallization of iPP as a nucleating factor. Mechanical properties, such as tensile strength, flexural strength, Young's modulus, tangent modulus, and microhardness are found to increase with increasing MWCNTs content. Thermal analyses represent an increase of crystallization and melting temperatures and a decrease of thermal stability of the composites with increasing MWCNTs. Changes in structural, mechanical, and thermal properties of the composites due to the addition of MWCNTs are elaborately discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effects of diatomite on extrudate swell behavior of polypropylene composite melts
Authors: Liang J. Z. 
Published: May 2010

AbstractExtrudate swell (i.e., die swell) is an important parameter for characterization of melt elasticity during extrusion of polymeric melts, and die swell ratio (B) is usually used to describe quantitatively the melt swell degree. The B of the polypropylene (PP) composites filled with diatomite particles was measured by means of a melt flow rate instrument to investigate the effects of the filler content and size on the die swell behavior of the composite system melts under the experimental conditions with temperature from 210 to 230°C and load varying from 1.2 to 7.5 kg. The particle diameters were 5, 7, and 13 μm, and the filler volume fractions were 5, 10, and 15%, respectively. The results showed that the B of the composites decreased nonlinearly with an increase of the filler volume fraction, whereas it increased as a quadratic function with an increase of the particle diameter when the load and temperature were fixed. It might be attributed to the interaction between the inclusions and the matrix, leading to blocking the recovery of the elastic deformation as the composite melts left from the die exit. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Surface modification of PHBV films with different functional groups: Thermal properties and in vitro degradation
Authors: Ke Yu , Wang Yingjun , Ren Li , Wu Gang , Xue Wei 
Published: May 2010

AbstractPolyacrylamide was photografted on solution‐cast poly(3‐hydroxybutyric acid‐co‐3‐hydroxyvaleric acid) (PHBV) films (amide‐PHBV), on which amide groups were transformed into amine groups through Hofmann degradation reaction (amine‐PHBV), followed by collagen coupling reaction to prepare collagen‐modified PHBV (collagen‐PHBV). Amide‐, amine‐, and collagen‐PHBV had higher water absorption and d‐spacing values than PHBV, and melting temperatures and enthalpies decreased in the order of collagen‐PHBV < amine‐PHBV < amide‐PHBV < PHBV. Thermal decomposition kinetics of PHBV component in the films has been investigated by means of nonisothermal thermogravimetric and derivative thermogravimetric studies. Applying the Avrami‐Erofeev equation with index of 2/5 as the probable kinetic function, the suitable activation energy was calculated by the Friedman method through linear fitting (correlation coefficient > 0.98). The activation energy of PHBV was lower than that of amide‐PHBV but higher than that of amine‐ and collagen‐PHBV. Being incubated in phosphate‐buffered saline at 37°C, the modified PHBV films showed more weight loss than PHBV during 360 days; however, pH of degradation fluids was nearly neutral as the initial pH was recorded at 7.2. The modified PHBV films with different functional groups may provide an improved biodegradation rate for various cytocompatible biomaterials constructs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Proteoglycans: Key Regulators of Pulmonary Inflammation and the Innate Immune Response to Lung Infection
Authors: Gill Sean , Wight Thomas N. , Frevert Charles W. 
Published: May 2010

AbstractExposure to viruses and bacteria results in lung infections and places a significant burden on public health. The innate immune system is an early warning system that recognizes viruses and bacteria, which results in the rapid production of inflammatory mediators such as cytokines and chemokines and the pulmonary recruitment of leukocytes. When leukocytes emigrate from the systemic circulation through the extracellular matrix (ECM) in response to lung infection they encounter proteoglycans, which consist of a core protein and their associated glycosaminoglycans. In this review, we discuss how proteoglycans serve to modify the pulmonary inflammatory response and leukocyte migration through a number of different mechanisms including: (1) The ability of soluble proteoglycans or fragments of glycosaminoglycans to activate Toll‐like receptor (TLRs) signaling pathways; (2) The binding and sequestration of cytokines, chemokines, and growth factors by proteoglycans; (3) the ability of proteoglycans and hyaluronan to facilitate leukocyte adhesion and sequestration; and (4) The interactions between proteoglycans and matrix metalloproteinases (MMP) that alter the function of these proteases. In conclusion, proteoglycans fine‐tune tissue inflammation through a number of different mechanisms. Clarification of the mechanisms whereby proteoglycans modulate the pulmonary inflammatory response will most likely lead to new therapeutic approaches to inflammatory lung disease and lung infection. Anat Rec, 293:968–981, 2010. © 2010 Wiley‐Liss, Inc.