bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Platinum on Diffusion Kinetics in β‐NiAl: Implications for Thermal Barrier Coating Lifetimes
Authors: Marino Kristen A. , Carter Emily A. 
Published: January 2009

AbstractPlatinum is added to thermal barrier coatings (TBCs) as it is observed empirically to extend their lifetime, but the mechanism by which Pt acts is unknown. Since Pt has been proposed to alter diffusivities in NiAl, a key component of TBCs, we use first‐principles quantum mechanics calculations to investigate atomic level diffusion mechanisms. Here, we examine the effect of Pt on five previously proposed mechanisms for Ni diffusion in NiAl: next‐nearest‐neighbor jumps, the triple defect mechanism, and three variants of the six jump cycle. We predict that Pt increases the rate of Ni diffusion by stabilizing point defects and defect clusters that are diffusion intermediates. Previously, we predicted the triple defect mechanism to be a dominant Ni diffusion mechanism; it simultaneously results in long‐range Al diffusion in the opposite direction. Since Pt increases the rate of Ni diffusion, it also increases Al diffusion in NiAl, which may be key to extending the coating lifetime.
Absolute CD4+ cell count using a plastic microchip and a microscopic cell counter
Authors: Bae Sook Young , Park Hae Chul , Oh Jun Seo , Yoon Soo‐Young , Park Dae Won , Choi In Keun , Kim Hae Joong , Oh Jong Hyun , Hur Dae Sung , Chung Chanil , Chang Jun Keun , Robinson J. Paul , Lim Chae Seung 
Published: January 2009

AbstractWe have designed and evaluated the performance of a simple, rapid, and affordable method for counting CD4+ T‐cells with the use of plastic microchips. This new system is an adaptation of a “no‐lyse, no‐wash,” volumetric single platform assay, and absolute CD4+ counts are determined with the use of a microscopic scanning cell counter. To assess the CD4+ count test precision and linearity of the system, measured CD4+ counts were compared with two other reference assays (single and dual platform flow cytometry) with the use of 123 clinical samples including samples obtained from 35 HIV‐infected patients, and artificially diluted samples. A correlation between the results from the use of the new method and from the use of the two other reference assays was r = 0.98 for the clinical samples. A dilution test of the new method demonstrated a linearity of r ≥ 0.99, with coefficients of variation ≤7.6% for all concentration levels. Our findings suggest that the new CD4+ counting device can be potentially be applied for other diagnostic procedures that measure quantities of characteristic antigens or other materials on cells. © 2009 Clinical Cytometry Society
Expression of the Pax2 transcription factor is associated with vestibular phenotype in the avian inner ear
Authors: Warchol Mark E. , Richardson Guy P. 
Published: January 2009

AbstractThe paired‐domain transcription factor Pax2 is involved in many facets of inner ear development, but relatively little is known about the expression or function of Pax2 in the mature ear. In this study, we have used immunohistochemical methods to characterize the expression patterns of Pax2 in the sensory organs of inner ears from posthatch chicks. Immunoreactivity for Pax2 was observed in the nuclei of most hair cells and supporting cells in the vestibular organs. In contrast, Pax2 expression in thechick cochlea was limited to hair cells located in the very distal (low frequency) region. We then used organotypic cultures of the chick utricle to examine changes in Pax2 expression in response to ototoxic injury and during hair cell regeneration. Treatment with streptomycin resulted in the loss of most Pax2 immunoreactivity from the lumenal (hair cell) stratum of the utricle. During the early phases of regeneration, moderate Pax2 expression was maintained in the nuclei of proliferating supporting cells. Expression of Pax2 in the hair cell stratum recovered in parallel with hair cell regeneration. The results indicate that Pax2 continues to be expressed in the mature avian ear, and that its expression pattern is correlated with a vestibular phenotype. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009
Division‐linked differentiation can account for CD8+ T‐cell phenotype in vivo
Authors: Schlub Timothy E. , Venturi Vanessa , Kedzierska Katherine , Wellard Cameron , Doherty Peter C. , Turner Stephen J. , Ribeiro Ruy M. , Hodgkin Philip D. , Davenport Miles P. 
Published: January 2009

AbstractThe CD8+ T‐cell response to infection involves a large initial expansion in the numbers of responding cells, accompanied by differentiation of these cells. Expression of the adhesion molecule CD62L is high on naïve cells and rapidly downregulated on the surface of the majority (∼90%) of cells during the ‘effector’ phase of acute infection. Adoptive transfer studies have been used to study differentiation in this system; however, relatively little work has investigated the phenotype of cells in the endogenous repertoire. We demonstrate that the extent of CD62L down‐regulation is positively correlated with clone size in vivo, consistent with division‐linked differentiation of responding cells. Other features of the endogenous CD62Lhi and CD62Llo repertoire are that the CD62Llo repertoire is less diverse than the CD62Lhi repertoire and represents a subset of clonotypes found in the CD62Lhi repertoire. To test whether these observations are compatible with a mechanism of division‐linked differentiation, we developed a mathematical model, where there is a probability of CD62L down‐regulation associated with cell division. Comparison of model results with experimental data suggests that division‐linked differentiation provides a simple mechanism to explain the relationship between clone size and phenotype of CD8+ T cells during acute infection.
Internalization of Dectin‐1 terminates induction of inflammatory responses
Authors: Hernanz‐Falcón Patricia , Joffre Olivier , Williams David L. , Reis e Sousa Caetano 
Published: January 2009

AbstractDectin‐1 is a pattern‐recognition receptor recognizing β‐(1,3)‐glucans found on fungal cell walls. Dectin‐1 plays an important role in immunity to fungi by mediating phagocytic clearance of fungal particles and inducing transcription of innate response genes. We show here that the two processes are linked and that Dectin‐1 signalling for inflammation is attenuated by phagocytosis. Blocking Dectin‐1 ligand‐dependent internalization using either actin polymerization or dynamin inhibitors, large non‐phagocytosable β‐glucan particles or poorly phagocytic cells leads in all cases to enhanced and sustained activation of downstream signalling pathways and culminates in production of high levels of pro‐inflammatory cytokines. These findings establish the importance of phagocytosis not only in the clearance of pathogens, but also in the modulation of pattern‐recognition receptor signalling and strongly suggest that internalization is the first step to attenuation of Dectin‐1‐mediated pro‐inflammatory responses.
The cellular niche of Listeria monocytogenes infection changes rapidly in the spleen
Authors: Aoshi Taiki , Carrero Javier A. , Konjufca Vjollca , Koide Yukio , Unanue Emil R. , Miller Mark J. 
Published: January 2009

AbstractThe spleen is an important organ for the host response to systemic bacterial infections. Many cell types and cell surface receptors have been shown to play role in the capture and control of bacteria, yet these are often studied individually and a coherent picture has yet to emerge of how various phagocytes collaborate to control bacterial infection. We analyzed the cellular distribution of Listeria monocytogenes (LM) in situ during the early phase of infection. Using an immunohistochemistry approach, five distinct phagocyte populations contained LM after i.v. challenge and accounted for roughly all bacterial signal in tissue sections. Our analysis showed that LM was initially captured by a wide range of phagocytes in the marginal zone, where the growth of LM appeared to be controlled. The cellular distribution of LM within phagocyte populations changed rapidly during the first few hours, decreasing in marginal zone macrophages and transiently increasing in CD11c+ DC. After 4–6 h LM was transported to the periarteriolar lymphoid sheath where the infective foci developed and LM grew exponentially.
Differential requirement for CARMA1 in agonist‐selected T‐cell development
Authors: Medoff Benjamin D. , Sandall Barry P. , Landry Aimee , Nagahama Kiyotaka , Mizoguchi Atsushi , Luster Andrew D. , Xavier Ramnik J. 
Published: January 2009

AbstractCaspase recruitment domain‐containing membrane‐associated guanylate kinase protein‐1 (CARMA1) is a critical component of the NF‐κB signaling cascade mediated by TCR engagement. In addition to activation of naïve T cells, TCR signaling is important for the development of agonist‐selected T‐cell subsets such as Treg, NKT cells, and CD8‐αα T cells. However, little is known about the role of CARMA1 in the development of these lineages. Here we show that CARMA1‐deficient mice (CARMA1−/−) have altered populations of specific subsets of agonist‐selected T cells. Specifically, CARMA1−/− mice have impaired natural and adaptive Treg development, whereas NKT cell numbers are normal compared with wild‐type mice. Interestingly, CD8‐αα T cells, which may also be able to develop through an extrathymic selection pathway, are enriched in the gut of CARMA1−/− mice, whereas memory‐phenotype CD4+ T cells (CD62Llow/CD44high) are present at reduced numbers in the periphery. These results indicate that CARMA1 is essential for Treg development, but is not necessary for the development of other agonist‐selected T‐cell subsets. Overall, these data reveal an important but differential role for CARMA1‐mediated TCR signaling in T‐cell development.
TGF‐β indirectly favors the development of human Th17 cells by inhibiting Th1 cells
Authors: Santarlasci Veronica , Maggi Laura , Capone Manuela , Frosali Francesca , Querci Valentina , De Palma Raffaele , Liotta Francesco , Cosmi Lorenzo , Maggi Enrico , Romagnani Sergio , Annunziato Francesco 
Published: January 2009

AbstractHuman Th17 clones and circulating Th17 cells showed lower susceptibility to the anti‐proliferative effect of TGF‐β than Th1 and Th2 clones or circulating Th1‐oriented T cells, respectively. Accordingly, human Th17 cells exhibited lower expression of clusterin, and higher Bcl‐2 expression and reduced apoptosis in the presence of TGF‐β, in comparison with Th1 cells. Umbilical cord blood naïve CD161+CD4+ T cells, which contain the precursors of human Th17 cells, differentiated into IL‐17A‐producing cells only in response to IL‐1β plus IL‐23, even in serum‐free cultures. TGF‐β had no effect on constitutive RORγt expression by umbilical cord blood CD161+ T cells but it increased the relative proportions of CD161+ T cells differentiating into Th17 cells in response to IL‐1β plus IL‐23, whereas under the same conditions it inhibited both T‐bet expression and Th1 development. These data suggest that TGF‐β is not critical for the differentiation of human Th17 cells, but indirectly favors their expansion because Th17 cells are poorly susceptible to its suppressive effects.
Pannexin‐1‐dependent caspase‐1 activation and secretion of IL‐1β is regulated by zinc
Authors: Brough David , Pelegrin Pablo , Rothwell Nancy J. 
Published: January 2009

AbstractInflammatory processes induced by IL‐1β are critical for host defence responses, but are also implicated in disease. Zinc deficiency is a common consequence of, or contributor to, human inflammatory disease. However, the molecular mechanisms through which zinc contributes to inflammatory disease remain largely unknown. We report here that zinc metabolism regulates caspase‐1 activation and IL‐1β secretion. One of the endogenous mediators of IL‐1β secretion is adenosine triphosphate, acting via the P2X7‐receptor and caspase‐1 activation in cells primed with an inflammatory stimulus such as LPS. We show that this process is selectively abolished by a brief pre‐treatment with the zinc chelator N,N,N′,N′‐tetrakis‐(2‐pyridylmethyl) ethylene diamine (TPEN). These effects on IL‐1β secretion were independent of rapid changes in free zinc within the cell, not a direct effect on caspase‐1 activity, and upstream of caspase‐1 activation. TPEN did however inhibit the activity of pannexin‐1, a hemi‐channel critical for adenosine triphosphate and nigericin‐induced IL‐1β release. These data provide new insights into the mechanisms of caspase‐1 activation and how zinc metabolism contributes to inflammatory mechanisms.
Inhibitory signaling potential of a TCR‐like molecule in lamprey
Authors: Yu Cuiling , Ehrhardt Götz R. A. , Alder Matthew N. , Cooper Max D. , Xu Anlong 
Published: January 2009

AbstractA TCR‐like molecule (TCRL) with two canonical ITIM has been identified in the sea lamprey. We show here that TCRL is preferentially expressed by lymphocytes bearing variable lymphocyte receptors. To examine the potential of the TCRL inhibitory motifs, chimeric proteins comprising the FcγRIIb extracellular and transmembrane domains and the TCRL intracellular domain were expressed in a mouse B‐cell line. BCR co‐ligation with the WT version of the FcγRIIb/TCRL chimeric protein resulted in its tyrosine phosphorylation and the inhibition of BCR‐induced calcium mobilization, whole‐cell protein tyrosine phosphorylation and Erk/Akt/JNK activation. Tyrosine to phenylalanine mutations in either or both ITIM compromised the inhibitory capacity of this receptor chimera. Analysis of receptor‐associated proteins indicated that the inhibition is mediated by recruitment of the protein tyrosine kinases, SHP1 and SHP2. These findings demonstrate the inhibitory potential of TCRL and its expression by clonally diverse lymphocytes bearing the variable lymphocyte receptors, thereby implying an immunomodulatory role for this ancestral TCR relative in a jawless vertebrate.
Chemistry of Polynuclear Cationic Gold(I) Thiolates of Formula [Au2(StBu)(L2)][BF4]
Authors: Diversi Pietro , Cuzzola Angela , Ghiotto Fabio 
Published: January 2009

AbstractThe reactivity of the gold(I) cationic complexes [Au2(StBu)(L2)][BF4] {L = PMe3, PEt3, PtBu3; L2 = dppe [dppe = 1,2‐bis(diphenylphosphanyl)ethane]} was studied. These complexes undergo cleavage of the Au–Au bonds by reaction with phosphanes to give quantitative yields of [Au(StBu)(L)n] and [Au(L)n][BF4] (n = 2 or 3) in the case of monodentate phosphanes, and [Au2(StBu)2(dppe)] and [Au(dppe)2][BF4] in the case of the dppe derivative. These compounds also react with [Au(StBu)(L)] and exchange the neutral moiety bonded to the [Au(L)]+ cation. In both cases some indication of the nature of the intermediates was reached by mass spectrometry (ESI) and NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Microwave‐Assisted Organometallic Syntheses: Formation of Dinuclear [(Arene)Ru(μ‐Cl)3RuCl(L–L′)] Complexes (L–L′: Chelate Ligands with P‐, N‐, or S‐Donor Atoms) by Displacement of Arene π Ligands
Authors: Albrecht Christian , Gauthier Sébastien , Wolf Joffrey , Scopelliti Rosario , Severin Kay 
Published: January 2009

AbstractMicrowave heating was employed to promote arene displacement in reactions of [{(p‐cymene)RuCl2}2] or [{(1,3,5‐C6H3iPr3)RuCl2}2] with neutral chelate ligands L–L′ [L–L′: 1,1′‐bis(diphenylphosphanyl)methane, 1,1′‐bis(diphenylphosphanyl)ferrocene, (S)‐BINAP, (S,S)‐DIOP, N,N′‐bis(2,4,6‐trimethylphenyl)‐1,2‐ethanediylidenediamine], (R)‐Ph‐PHOX, and 3‐(phenylsulfanylpropyl)diphenylphosphane. The reactions gave complexes of the general formula [(arene)Ru(μ‐Cl)3RuCl(L–L′)] in good yield. The synthesis of [(p‐cymene)Ru(μ‐Cl)3RuCl{PPh2(CH2)3NH2}] (22) was accomplished in two steps via the intermediate [{(p‐cymene)RuCl2}2{μ‐PPh2(CH2)3NH2}] (21). The structures of [(1,3,5‐C6H3iPr3)Ru(μ‐Cl)3RuCl(dppf)] (16), [(1,3,5‐C6H3iPr3)Ru(μ‐Cl)3RuCl{(S)‐BINAP}] (17), and [(p‐cymene)Ru(μ‐Cl)3RuCl(MesNCHCHNMes)] (18) were determined by single‐crystal X‐ray diffraction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Chiral Oxazoline‐NHC Ligands with and without CR2 Bridges: A Comparative Study in Rhodium Hydrosilylation Catalysis
Authors: Schneider Nathanaëlle , Kruck Matthias , Bellemin‐Laponnaz Stéphane , Wadepohl Hubert , Gade Lutz H. 
Published: January 2009

AbstractA series of bidentate oxazoline‐NHC ligands has been synthesized in which the two heterocycles are connected by a CH2 linker. The corresponding rhodium(I) complexes were prepared by direct deprotonation of the imidazolium halide salts followed by the addition of a solution of [Rh(nbd)Cl]2 at low temperature. The cationic square planar rhodium complexes were generated by halide abstraction via addition of an excess of KPF6 in a CH2Cl2/water solvent system. Alternatively, the deprotonation of the imidazolium hexafluorophosphates and reaction with [Rh(nbd)Cl]2 directly gave the complex cations. These as well as oxazoline‐NHC systems, in which the two heterocycles are directly connected or through a CMe2 bridge, were investigated in the rhodium‐catalyzed hydrosilylation of acetophenone. The comparison of the three ligand families showed that the catalysts obtained by direct coupling of oxazolines and N‐heterocyclic carbenes, generating highly rigid chelate ligands, remain the most efficient systems giving the secondary alcohols in high enantioselectivity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Bridged 5,6,7,8‐Tetrahydro‐1,6‐naphthyridines, Analogues of Huperzine A: Synthesis, Modelling Studies and Evaluation as Inhibitors of Acetylcholinesterase
Authors: Vanlaer Sofie , Voet Arnout , Gielens Constant , De Maeyer Marc , Compernolle Frans 
Published: January 2009

AbstractDerivatives of 6,8‐bridged 5,6,7,8‐tetrahydro‐1,6‐naphthyridines, designed as analogues of huperzine A, were synthesised and evaluated as inhibitors of acetylcholinesterase. In a first approach, C3‐bridged naphthyridines were constructed by internal nucleophilic aromatic substitution of 2‐chloro‐3‐(1‐piperidinylmethyl)pyridine precursors containing a 3‐CO2Me group on the 1‐piperidinyl ring moiety. Alternatively, ring‐closing metathesis on 6,8‐diallyl‐substituted tetrahydro‐1,6‐naphthyridines was applied to construct an unsaturated C4bridge. Some of the target compounds showed inhibition of acetylcholinesterase but lower than that of huperzine A. The relative order of inhibition activities could be rationalised by comparative docking simulation studies on the basis of the known crystal structure of the acetylcholinesterase–huperzine A complex.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Total Synthesis of (+)‐Varitriol
Authors: Palík Miroslav , Karlubíková Ol'ga , Lásiková Angelika , Kožíšek Jozef , Gracza Tibor 
Published: January 2009

AbstractThe total synthesis of natural (+)‐varitriol (1) was accomplished by starting from dimethyl L‐tartrate. The keyfeatures were a substrate selective and diastereoselective PdII‐catalysed bicyclisation of unsaturated protected triol 9 followed by regioselective ring‐opening of bicyclic skeleton 10. The absolute configuration of the target was confirmed by single‐crystal X‐ray analysis for the first time.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Electrohydrodynamic‐mediated dielectrophoretic separation and transport based on asymmetric electrode pairs
Authors: Du E. , Manoochehri Souran 
Published: January 2009

AbstractThis paper presents a system for continuous separation and transport of micron and submicron particles in fluidic environment based on dielectrophoretic fractionation in concert with AC electrothermal (AC ET)‐induced fluidic pumping action. In this system, high frequency AC signals are used to energize asymmetric electrode pairs. AC ET‐driven fluidic pumping is utilized as an alternative to the commonly used external pressure‐driven fluid flow. Distinct collection sites for negative‐dielectrophoretic and positive‐dielectrophoretic particle populations are identified. The coupling effects of dielectrophoretic force and viscous drag from AC ET fluid flow on particle motions are investigated theoretically and numerically. We demonstrate that these two forces can be efficiently coupled to achieve continuous separation and transport of particle mixture in a fluidic medium when the dielectric properties of the particles and the fluidic environment are different. The combination of dielectrophoretic separation and AC ET pumping function provides a promising approach to further miniaturize and integrate these mechanisms into lab‐on‐chip devices.
Lab‐on‐a‐robot: Integrated microchip CE, power supply, electrochemical detector, wireless unit, and mobile platform
Authors: Berg Christopher , Valdez David C. , Bergeron Phillip , Mora Maria F. , Garcia Carlos D. , Ayon Arturo 
Published: January 2009

AbstractIn this paper, the fabrication of a wireless mobile unit containing an electrochemical detection module and a 3‐channel high‐voltage power supply (HVPS) designed for microchip CE is described. The presented device consists of wireless global positioning system controlled robotics, an electrochemical detector utilizing signal conditioning analog circuitry and a digital feedback range controller, a HVPS, an air pump, and a CE microchip. A graphical user interface (LabVIEW) was also designed to communicate wirelessly with the device, from a distant personal computer communication port. The entire device is integrated and controlled by digital hardware implemented on a field programmable gate array development board. This lab‐on‐a‐robot is able to navigate to a global position location, acquire an air sample, perform the analysis (injection, separation, and detection), and send the data (electropherogram) to a remote station without exposing the analyst to the testing environment.
Rapid chip‐based capillary electrophoretic mobility shift assay with negative pressure injection for the binding study of transcription factor Abf1 in Saccharomyces cerevisiae
Authors: Yang Qian , Zhao Yong‐Chao , Xiong Qiang , Cheng Jing 
Published: January 2009

AbstractThe study on the interactions of nucleic acids with transcription factor (TF) is critical to understand the gene expression at the molecular level. In the present study, a rapid chip‐based capillary electrophoretic mobility shift assay with LIF detection has been developed on a PDMS‐quartz chip. We used a simple negative pressure injection procedure to avoid the bias of electrokinetic injection and to allow loading of the high salt buffered sample. We observed signals for Cy3‐labelled oligonucleotides with a 2.6% RSD in peak height. The specific binding of TF autonomously replicating sequence‐binding factor 1 (Abf1), either recombinant Abf1 or endogenous Abf1 in yeast cell extracts, with Cy3‐labelled specific capture dsDNA could be analyzed on the uncoated chip filled with 2% hydroxypropylcellulose sieving matrix within 100 s. The specificity of the TF–DNA complex was confirmed by both competition experiment and supershift assay. The interactions between Abf1 in the range from 0.156 to 80 nM and dsDNA capture molecules were examined and a detection limit of 0.156 nM Abf1 was found. The uncoated chip capillary electrophoretic mobility shift assay method described here demonstrated great potential for fast, qualitative and quantitative analysis of protein–DNA interaction with low consumption of samples.