bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pathogenic T cells in MOBP‐induced murine EAE are predominantly focused to recognition of MOBP21F and MOBP27P epitopic residues
Authors: Kaushansky Nathali , Zilkha‐Falb Rina , Hemo Reut , Lassman Hans , Eisenstein Miriam , Sas Aldema , Ben‐Nun Avraham 
Published: October 2007

AbstractMyelin‐associated oligodendrocytic basic protein (MOBP) is a central nervous system (CNS)‐specific myelin constituent important in stabilizing the unique multi‐layered structure of the CNS‐myelin sheath. Although autoimmunity against MOBP has been associated with multiple sclerosis pathogenesis, anti‐MOBP pathogenic T cells have been poorly investigated as compared to T cells against other encephalitogenic myelin proteins. We have recently determined MOBP15–36 as the major encephalitogenic epitope of MOBP for SJL/J mice. In this study, epitope‐specificity was dissected to the level of residues crucial for activation/control of MOBP‐specific encephalitogenic T cells. Structural bioinformatic analysis of MOBP15–36/I‐As interaction and experimental data have determined MOBP21F and MOBP27P of I‐As‐binding nonameric core epitope (MOBP20–28) as TCR‐contact residues critical for functional activation of encephalitogenic MOBP‐specific T cells. Accordingly, the non‐encephalitogenic/nonstimulatory pMOBP16–21A27A‐33 inhibited encephalitogenic MOBP‐reactive T cells, shifted their cytokine secretion profile, and effectively suppressed pMOBP15–36‐induced EAE. Moreover, pMOBP16–21A27A‐33 fully reversed ongoing clinical EAE induced by whole MOBP as well as by pMOBP15–36. Data show that encephalitogenic MOBP‐reactive T cells are predominantly focused to recognition of MOBP21F and MOBP27P, and suggest that both their selection and control are governed by MOBP21F and MOBP27P epitopic residues. Such focused epitopic recognition may affect profoundly on peripheral self‐tolerance to MOBP and on potential altered peptide ligand‐mediated therapy of MOBP‐related autoimmune pathogenesis.
Critical role for Ipaf in Pseudomonas aeruginosa‐induced caspase‐1 activation
Authors: Franchi Luigi , Stoolman Joshua , Kanneganti Thirumala‐Devi , Verma Amrisha , Ramphal Reuben , Núñez Gabriel 
Published: October 2007

AbstractPseudomonas aeruginosa is an opportunistic Gram‐negative human pathogen that is responsible for a broad range of infections in individuals with a variety of predisposing conditions. After infection, P. aeruginosa induces a marked inflammatory response in the host. However the mechanisms involved in bacterium recognition and induction of immune responses are poorly understood. Here we report that the Nod‐like receptor family member Ipaf is required for optimal bacterial clearance in an in vivo model of P. aeruginosa lung infection. Further analysis showed that bacterial flagellin was essential for caspase‐1 and IL‐1β and this activity depended on Ipaf and the adaptor ASC but not TLR5. Notably, P. aeruginosa induced macrophage cell death and this event relied on flagellin and Ipaf but not on ASC. Analysis of Pseudomonas mutants revealed that different amino acid residues of flagellin were critical for sensing by Ipaf and TLR5. Finally, activation of caspase‐1 and IL‐1β secretion by P. aeruginosa required a functional type III secretion system, but not the effector molecules ExoS, ExoT and ExoY. These results provide new insight into the interaction of P. aeruginosa with host macrophages and suggest that distinct regions of flagellin are sensed by Ipaf and TLR5.
Non‐redundant role for IL‐7R signaling for the survival of CD8+ memory T cells
Authors: Carrio Roberto , Rolle Cleo E. , Malek Thomas R. 
Published: October 2007

AbstractIL‐7 and IL‐15 are important cytokines for CD8 memory T cells. However, the extent that IL‐7 is essential for CD8 T cell memory remains unclear because blocking IL‐7 in vivo results in near complete inhibition of T cell development with the few mature T cells exhibiting functional abnormalities. To bypass this complication, CD8 memory development was examined utilizing a mouse model where transgenic IL‐7Rα was selectively expressed in the thymus of IL‐7Rα–/– mice. T cell development was corrected but the resulting peripheral T cells were essentially IL‐7 non‐responsive. Activation of IL‐7R‐defective OT‐I CD8+ T cells with OVA257–264 and IL‐2 readily yielded CTL. Upon further culture with IL‐15, these CTL expressed phenotypic and functional properties of central memory‐like cells. Thus, IL‐7R‐defective CD8+ T cells do not exhibit intrinsic defects in effector or memory development. When IL‐7R‐defective OT‐I CTL were adoptively transferred into normal or IL‐15–/– recipient mice in a non‐inflammatory setting, they converted into memory‐like cells, but did not persist, which was even more striking in IL‐15–/– recipients. This poor persistence was rescued after expression of transgenic Bcl‐2 in IL‐7R‐defective OT‐I T cells. Collectively, these data indicate that IL‐7 is non‐redundantly required for the survival of CD8 memory T cells.
Luminescent Organically Templated Lanthanide Oxalate–Selenate Hybrids
Authors: Feng Mei‐Ling , Mao Jiang‐Gao 
Published: October 2007

AbstractHydrothermal reactions of lanthanide nitrates with selenic acid, sodium oxalate, and organic amines led to two series of new organically templated lanthanide oxalate–selenate hybrids with 2D‐layer or 3D‐network structures, namely, Ln2(SeO4)2(C2O4)(H2O)4·pip (Ln = Eu 1; Tb 2; Dy 3; Er 4; Yb 5) (pip = piperazine) and [H2pip]2[Ln2(SeO4)2(C2O4)3]·H2O (Ln = Er 6; Yb 7; Lu 8; Y 9). Their structures were established by X‐ray single‐crystal diffraction. Isostructural compounds 1–5 feature a 2D inorganic–organic hybrid neutral layer of Ln2(SeO4)2(C2O4)(H2O)4. The neutral piperazine molecules are located at the interlayer spaces and interconnect with the inorganic skeleton through hydrogen bonds. Compounds 6–9 are isostructural and possess 3D pillared layered architectures composed of lanthanide oxalate layers bridged by selenate anions (the pillar). The template cations are located at the tunnels of the structure. Compounds 1, 2, and 3 display emission bands in the red‐, green‐, and pink‐light regions, respectively, and these compounds have lifetimes of 0.178, 0.962, and 0.276 ms, respectively. Compounds 6 and 7 both exhibit emission bands in the near‐IR region. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Enantiopure Mono‐ and Mixed‐Valence Multinuclear Cobalt Complexes from Amino Alcohol Based Ligands
Authors: Pradeep Chullikkattil P. , Zacharias Panthapally S. , Das Samar K. 
Published: October 2007

AbstractChiral amino alcohol based tridentate Schiff bases, derived from 5‐OMe‐, 5‐H‐, and 5‐NO2‐substituted salicylaldehydes and (S)‐(+)‐2‐phenylglycinol and (S)‐(–)‐2‐amino‐3‐phenyl‐1‐propanol, were found to act as versatile ligands in their coordination behavior towards cobalt and gave a range of complexes like mononuclear low‐spin CoIII complexes, mixed‐valence trinuclear CoIII–CoII–CoIII complexes, and a mixed‐valence tetranuclear (CoIII)3CoII complex on 1:1 molar ratio reaction with Co(CH3COO)2·4H2O in methanol at room temperature. The steric and electronic properties of these ligands are found to control the overall geometry and nuclearity of the resulting complexes. 5‐OMe‐Substituted ligands (H2L1 and H2L2) gave mononuclear low‐spin CoIII complexes [CoL1(HL1)]·0.25DMF (1) and [CoL2(HL2)]·0.25DMF (2). Single‐crystal X‐ray structure analysis of complex 2 revealed that the relevant complex crystallizes with four mononuclear units in the asymmetric unit (Z′ = 4), and these units self‐assemble through O–H···O hydrogen‐bonding interactions resulting in the formation of homochiral supramolecular helices in the crystal lattice. The 5‐H‐ and 5‐NO2‐substituted ligands (H2L3, H2L4, H2L5) afforded mixed‐valence trinuclear CoIII–CoII–CoIII complexes [Co(CoL32)2·H2O]·2DMF·2H2O (3), [Co(CoL42)2·H2O]·2DMF·H2O (4), and [Co(CoL52)2·DMF]·2DMF·H2O (5), respectively. Crystal structure analyses of complexes 3 and 5 revealed rare trinuclear geometries of these complexes, in which two terminal octahedral low‐spin CoIII complexes act as chelating ligands for a central high‐spin CoII center through alkoxide bridging. For steric reasons, the central cobalt adopts a highly distorted geometry in these complexes viz. distorted trigonal bipyramidal in complex 3 and distorted square planar in complex 5. The ligand H2L6 gave an interesting tetranuclear mixed‐valence complex, H[Co(CoL62)3]·H2O (6), in which three octahedral low‐spin CoIII complexes act as ligands for a central high‐spin CoII center in distorted trigonal prismatic geometry. Interestingly, the three types (mononuclear: 1, 2; trinuclear: 3, 4, 5; tetranuclear: 6) of complexes showed large variations in their nuclearity and overall geometry despite the fact that the experimental conditions for all these complexes were identical. This fact highlights the influence of different substitutions on ligands in determining the final geometry of the resulting complexes in these reactions. Complexes 1–6 were characterized by elemental and routine spectral analyses. Compounds 2, 3, 5, and 6 have been unequivocally characterized by single‐crystal X‐ray structure determinations as well. Chiral properties of these complexes were confirmed by circular dichroism (CD) spectral studies.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Critical Effect of Phosphane Ligands on the Mechanism of Carbon–Carbon Bond Formation Involving Palladium(II) Complexes: A Theoretical Investigation of Reductive Elimination from Square‐Planar and T‐Shaped Species
Authors: Ananikov Valentine P. , Musaev Djamaladdin G. , Morokuma Keiji 
Published: October 2007

AbstractA theoretical ONIOM study has been carried out to understand the influence of phosphane ligands on the structure of Pd complexes and their reactivity in C–C bond formation. The calculations were performed for Me–Me reductive elimination with the ligands L = PPh3, PCy3, PMe3, PH3, and vinyl–vinyl, Ph–Ph, ethynyl–ethynyl, vinyl–Me, vinyl–Ph and vinyl–ethynyl couplings with L = PPh3 for [PdR2Ln] complexes (n = 1, 2). The calculations revealed critical changes in the reactivity of palladium complexes depending on the mechanism and ligand type. In the case of the standard four‐coordinate pathway (n = 2) the relative reactivity in carbon–carbon bond formation follows the order: L = PPh3 > PH3 > PCy3 > PMe3. However, for reductive elimination involving T‐shaped complexes by the ligand predissociation pathway (n = 1), the relative reactivity changes in the order: L = PCy3 > PPh3 > PH3 > PMe3. The theoretical study suggested that the steric effect of phosphane ligands has the largest impact on the structure of the initial palladium complexes, while the electronic effect is most influential on the transition states of C–C coupling in these complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Selenium‐Containing Tetrachalcogenins and Pentachalcogenepins Fused to Aromatic Systems
Authors: Alam Ashraful , Ogawa Satoshi , Muraoka Hiroki , Kon‐no Masaru , Nakajo Shiduko , Sato Ryu 
Published: October 2007

AbstractVarious ring‐sized cyclic polychalcogenides fused to aromatic systems were synthesized, and the structures were sufficiently characterized. Stabilities of the rings were examined in terms of the existence of selenium atoms. Benzopolychalcogenides are unstable molecules. However, benzo[1,2,3,4,5]tetrathiaselenepins with an isopropyl group or two methoxy groups on the ring were found to be stable. Similarly, the novel benzo[2,3,4,1,5]trithiadiselenepin ring was also stabilized by two methoxy groups. Benzo[1,2,3,4]trithiaselenin and benzo[2,3,1,4]dithiadiselenin were also synthesized by a controlled reaction with S2Cl2 at –78 °C. The ring systems were sensitive to air, moisture, light, and polar solvents. Extended π‐systems such as naphthalene and phenanthrene showed remarkable thermodynamic stability toward unstable rings. The unprecedented stabilities possessed by the polyaromatics are yet unclear. Phenanthro[9,10‐d][1,2,3]dithiaselenole was also successfully isolated as a novel molecule. It is the first isolated trichalcogenole having one selenium atom, which is stabilized by an extended π system. Phenanthro[9,10‐f][1,2,3,4,5]tetrathiaselenepin is stable in the solid state. The use of polar solvents under ambient conditions resulted in the extrusion of selenium from the ring to generate more stable trithiole rings. The structures of the five‐, six‐, and seven‐membered cyclic polychalcogenides were extensively established in this report.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A Penicillamine Biosensor Based on Tyrosinase Immobilized on Nano‐Au/ PAMAM Dendrimer Modified Gold Electrode
Authors: Li Nian Bing , Kwak Juhyoun 
Published: October 2007

AbstractGold electrodes were modified with submonolayers of 3‐mercaptopropionic acid and further reacted with poly(amidoamine) (PAMAM) dendrimers to obtain thin films. The high affinity of PAMAM dendrimer for nano‐Au with its amine groups was used to realize the role of nano‐Au as an intermediator to immobilize the enzyme of tyrosinase. The characterization of the modified electrode was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy (AFM). Tyrosinase can catalyze the oxidation of catechol to o‐benzoquinone. When penicillamine was added to the solution, it reacted with o‐benzoquinone to form the corresponding thioquinone derivatives, which resulted in decrease of the reduction current of o‐benzoquinone. Based on this, a new electrochemical sensor for determination of penicillamine has been developed.
Kinetics and Mechanism of Ni(II) Chelation in Model and Real Solutions of Xylem Sap of Quercus ilex
Authors: Correia dos Santos Margarida Maria , Alves Sheila , de Lurdes Simões Gonçalves Maria 
Published: October 2007

AbstractThe kinetics of formation and dissociation of Ni(II) complexes with oxalic and citric acids was studied by cyclic voltammetry in model solutions of xylem sap of Q. ilex (the dominant tree growing on serpentine soils of Northeast Portugal) using representative concentrations, pH and ionic strength. The role of magnesium on complex formation was analyzed from solutions where Mg is present at concentration levels found in the xylem sap of Q. ilex growing on both nonserpentine and serpentine soils. Kinetics studies were also done in diluted solutions of real xylem sap samples, spiked with increasing amounts of magnesium. The values obtained for the apparent rate constants were those anticipated by the proposed model. To test the validity of the methodology and mechanisms, formation rate constants, kf (M−1 s−1) of Ni(II) complexes with citrate and oxalate were evaluated that compare with the values from Eigen mechanism.
DNA Assisted Assembly of Multisegmented Nanowires
Authors: Lee Joun , Wang Aijun A. , Rheem Youngwoo , Yoo Bongyoung , Mulchandani Ashok , Chen Wilfred , Myung Nosang V. 
Published: October 2007

AbstractThis work demonstrates a highly specific and selective assembly of multisegmented nanowires on prepatterned gold electrodes using DNA hybridization. Multisegmented Au/Pd/Au nanowires were synthesized using template‐directed electrodeposition. Two complementary single‐stranded DNAs modified with thiol tags adsorb on gold electrodes and gold segments of nanowires, and enable the nanowires to assemble across electrodes. The assembled nanowires show ohmic contact with minimum contact resistance. Using these nanowires, the temperature dependent electrical resistance and the sensing performance toward hydrogen were investigated. The temperature coefficient of resistance of nanowires was lower than bulk polycrystalline counterpart, because of higher electron scattering at the surface and grain boundaries of nanowires. The nanowires were sensitive toward hydrogen gas at room temperature with a detection limit of 0.5%.
Direct Electrochemical Sensing and Detection of Natural Antioxidants and Antioxidant Capacity in Vitro Systems
Authors: Blasco Antonio Javier , González Crevillén Agustín , González María Cristina , Escarpa Alberto 
Published: October 2007

AbstractThis review highlights the role of electrochemical approaches in the sensing of antioxidants and their antioxidant capacity with especial attention to the analytical possibilities of electrochemistry in the direct evaluation of antioxidant capacity exhibited by food and biological samples due to the termed dietary, natural or biological antioxidants (mainly polyphenols, and vitamins C and E). The analytical potency of the electrochemistry is comprehensively stated and the selected results found in the literature are summarized and discussed critically. The main electrochemical approaches used have been cyclic voltammetry (CV) and flow injection analysis with amperometric detection (FIA‐ED). In addition, miniaturization is going to break new frontiers in the evaluation of antioxidant activity.
Direct Electrochemistry of Cytochrome P450 Reductases in Surfactant and Polyion Films
Authors: Sultana Nasreen , Schenkman John B. , Rusling James F. 
Published: October 2007

AbstractNADPH‐cytochrome P450 reductase (CPR) serves as electron donor for cytochrome P450 catalyzed monooxygenase reactions utilizing flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) as electron transfer cofactors. Here, stable films of human and rabbit CPRs with didodecyldimethylammonium bromide (DDAB), dimyristoylphosphatidyl choline (DMPC), and poly(diallyldimethylammonium) (PDDA) were made on pyrolytic graphite (PG) electrodes for comparative structural and electrochemical studies. CD and UV‐VIS absorbance spectra suggested that near native CPR conformation is retained in PDDA films, and some conformational changes occur in DMPC or DDAB films. Cyclic voltammetry of these films gave quasireversible pairs of peaks at average formal potential −0.246±0.008 V vs. NHE. In human CPR‐DDAB (H‐CPR‐DDAB), a second pair of peaks at +0.317 V vs. NHE was found that depended strongly on identity of buffer and salt. Excepting H‐CPR in DDAB, films showed similar voltammetry, formal potentials, and ks values. While CPR‐PDDA films had near native CPR structures, electrochemical parameters did not differ significantly from CPR‐DMPC films. The relative independence of film voltammetry from the influence of film materials for CPRs is in contrast with heme iron proteins that, while retaining near native structures, have formal potentials that depend significantly on identity of the film material.
Comparison of Boron‐Doped Diamond and Glassy Carbon Electrodes for Determination of Procaine Hydrochloride
Authors: Wei Min , Zhou Yanli , Zhi Jinfang , Fu Degang , Einaga Yasuaki , Fujishima Akira , Wang Xuemei , Gu Zhongze 
Published: October 2007

AbstractThe electrochemical oxidation of procaine hydrochloride (PC⋅HCL, 2‐diethylaminoethyl 4‐aminobenzoate hydrochloride) was investigated at as‐deposited boron‐doped diamond (ad‐BDD) electrode, anodically oxidized BDD (ao‐BDD) electrode and glassy carbon (GC) electrode using cyclic voltammetry (CV). Well‐defined cyclic voltammograms were obtained for PC⋅HCL oxidation with high signal‐to‐background (S/B) ratio, low tendency for adsorption, good reproducibility and long‐term stability at ad‐BDD electrode, demonstrating its superior electrochemical behavior and significant advantages in contrast to ao‐BDD and GC electrode. At 100 μM PC⋅HCL, the voltammetric S/B ratio was nearly one order of magnitude higher at an ad‐BDD electrode than that at a GC electrode. In a separate set of experiments for oxidation of 100 μM PC⋅HCL, 96%, 92% and 84% of the initial oxidation peak current was retained at the ad‐BDD, ao‐BDD and GC electrode, respectively, by stirring the solution after the tenth cycle. The current response was linearly proportional to the square root of the scan rate within the range 10–1000 mV s−1 in 10 μM PC⋅HCL solutions, indicating that the oxidation process was diffusion‐controlled with negligible adsorption at an ad‐BDD surface. The good linearity was observed for a concentration range from 5 to 200 μM with a linear equation of y=0.03517x+0.65346 (r=0.999), and the detection limit was 0.5 μM for oxidation of PC⋅HCL at the ad‐BDD electrode. The ad‐BDD electrode could maintain 100% of its original activity after intermittent use for 3 months.
Properties of the Contactless Impedance Detector with Insulated Wire Electrodes Placed Inside the Flowing Liquid Stream
Authors: Nádherná Martina , Opekar František , Štulík Karel 
Published: October 2007

AbstractThe behavior of a flow cell, in which the impedance is measured between two insulated wire electrodes located within the stream of the test liquid, is described and compared with that of a semi‐quantitative theoretical model. A new approach is used to the monitoring of the impedance signal, based on connecting the cell as the input impedance of an operational amplifier in the differentiating circuit. A triangular AC voltage is fed to one of the electrodes and the other electrode is connected to the amplifier input. The square‐wave voltage at the amplifier output depends at low frequencies (from hundreds of Hz to several kHz) on the capacitive component of the overall impedance. The basic analytical parameters are in satisfactory agreement with the model and are comparable to those obtained with common contactless impedance detectors operating at higher frequencies of hundreds of kHz to a few MHz and monitoring primarily the conductance component of the impedance. The system described offers new detection possibilities, mainly for nonionic analytes of varying polarities.
Voltammetric Detection of Ofloxacin in Human Urine at a Congo Red Functionalized Water‐Soluble Carbon Nanotube Film Electrode
Authors: Yang Chunhai , Xu Yanxia , Hu Chengguo , Hu Shengshui 
Published: October 2007

AbstractA simple physical method was developed for the surface modification and the solubilization of MWNTs in water by Congo red. The resulting water‐soluble MWNTs (MWNTs‐CR) can form stable and uniform films on solid supports when dried, which was used to fabricate MWNTs‐CR modified glassy carbon electrodes (MWNTs‐CR/GCE). Voltammetric studies showed that MWNTs‐CR/GCE exhibited a strong enhancement effect on the electrooxidation of ofloxacin. MWNTs‐CR films were also proved to possess overwhelming advantages as electrochemical sensing films over other commonly used MWNTs composite films (e.g., MWNTs‐DHP and MWNTs‐Nafion), reflected by the higher oxidation current, lower background and stronger accumulation capacity towards less soluble species. The sensitive oxidation of ofloxacin at MWNTs‐CR/GCE was used for the determination of ofloxacin. Under optimal conditions, the oxidation current was proportional to ofloxacin concentration in the ranges of 5×10−8–3.0×10−5 M. The detection limit of 9×10−9 M was obtained for 350 s accumulation at open circuit (S/N=3). This method was applied to the determination of ofloxacin in human urine and the result was satisfying.