bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accelerating and Decelerating Effects of Metal Ions on Electron‐Transfer Reduction of Quinones as a Function of Temperature and Binding Modes of Metal Ions to Semiquinone Radical Anions
Authors: Yuasa Junpei , Yamada Shunsuke , Fukuzumi Shunichi 
Published: December 2007

AbstractThe accelerating effect of Sc3+ on the electron‐transfer (ET) reduction of the p‐benzoquinone derivative 1‐(p‐tolylsulfinyl)‐2,5‐benzoquinone (TolSQ) by 10,10′‐dimethyl‐9,9′‐biacridine ((AcrH)2) at 233 K changes to a decelerating effect with increasing reaction temperature; the observed second‐order rate constant ket decreases with increasing Sc3+ concentration at high concentrations of Sc3+ at 298 K. At 263 K the ket value remains constant with increasing Sc3+ concentration. Such a remarkable difference with regard to dependence of ket on [Sc3+] between low and high temperatures results from the difference in relative activity of two ET pathways that depend on temperature, one of which affords 1:1 complex TolSQ.−–Sc3+, and the other 1:2 complex TolSQ.−–(Sc3+)2 with additional binding of Sc3+ to TolSQ.−–Sc3+. The formation of TolSQ.−–Sc3+ and TolSQ.−–(Sc3+)2 complexes was confirmed by EPR spectroscopy in the ET reduction of TolSQ in the presence of low and high concentrations of Sc3+, respectively. The effects of metal ions on other ET reactions of quinones to afford 1:1 and 1:2 complexes between semiquinone radical anions and metal ions are also reported. The ET pathway affording the 1:2 complexes has smaller activation enthalpies ΔH≠ and more negative activation entropies ΔS≠ because of stronger binding of metal ions and more restricted geometries of the ET transition states as compared with the ET pathway to afford the 1:1 complexes.
Explorations of New Types of Second‐Order Nonlinear Optical Materials in Cd(Zn)‐VV‐TeIV‐O Systems
Authors: Jiang Hai‐Long , Huang Shu‐Ping , Fan Yang , Mao Jiang‐Gao , Cheng Wen‐Dan 
Published: December 2007

AbstractSolid‐state reactions of zinc(II) or cadmium(II) oxide, V2O5, and TeO2 at high temperature led to two novel quaternary compounds, namely, Zn3V2TeO10 and Cd4V2Te3O15. The structure of Zn3V2TeO10 is a complicated three‐dimensional (3D) network constructed by the interconnection of ZnO5, ZnO6, VO4, and TeO4 polyhedra via corner‐ and edge‐sharing. Cd4V2Te3O15 with an acentric structure features a 3D network in which the cadmium tellurite layers are further interconnected by both “isolated” VO4 tetrahedra and one‐dimensional (1D) vanadium oxide helical chains. Cd4V2Te3O15 displays a second harmonic generation (SHG) efficiency of about 1.4 times that of KH2PO4 (KDP). Both compounds are direct band‐gap semiconductors and are transparent in the range of 0.6–10.0 μm. Measurements of luminescence indicate that both compounds exhibit broad emission bands in the blue‐light region.
Comparative studies on pharmacokinetic fates of tetrahydropalmatine enantiomers in different chemical environments in rats
Authors: Hong Zhanying , Le Jian , Lin Mei , Fan Guorong , Chai Yifeng , Yin Xueping , Wu Yutian 
Published: December 2007

AbstractTetrahydropalmatine (THP) is the active component in Rhizoma corydalis and the medicine Yuanhu‐Baizhi (YB), which consists of Rhizoma corydalis and Radix angelicae dahuricae. The aim of this work was to compare pharmacokinetic features of THP enantiomers in rats dosed with racemic THP (rac‐THP), Rhizoma corydalis, or YB extracts. A single dose of rac‐THP (5 mg kg−1) or extracts of Rhizoma corydalis and YB (both equivalent to 5 mg kg−1 of rac‐THP) was given orally to three groups of Sprague‐Dawley rats, respectively. Blood samples were collected periodically and plasma concentrations of THP enantiomers were determined using an achiral–chiral high‐performance liquid chromatographic (HPLC) method previously reported, with some modifications. The Cmax ratio (−/+) of THP was 2.91, 1.38, and 1.19, and the AUC0∼∞ ratio (−/+) of THP was 2.84, 1.50, and 1.35 in rats after dosed with rac‐THP, extracts of Rhizoma corydalis and YB, respectively. The mean AUC0∼∞ and Cmax of (+)‐THP dosed with YB extracts were 0.652 ± 0.30 μg h ml−1 and 0.148 ± 0.09 μg ml−1, significantly higher (P < 0.05) than those dosed with rac‐THP and Rhizoma corydalis extracts. The mean AUC0∼∞ and Tmax of rac‐THP dosed with YB extracts were 1.500 ± 0.56 μg h ml−1 and 2.12 ± 1.1 h, significantly higher (P < 0.05) than those dosed with rac‐THP or Rhizoma corydalis extracts. These findings suggested the stereoselectivity in pharmacokinetics of THP enantiomers in rats was decreased when dosed in plant form, while the AUC0∼∞ of rac‐THP increased when YB extracts were dosed, confirming the compatibility in drug combination of Rhizoma corydalis and Radix angelicae dahuricae. Chirality, 2008. © 2007 Wiley‐Liss, Inc.
Patterning the embryonic kidney: BMP signaling mediates the differentiation of the pronephric tubules and duct in Xenopus laevis
Authors: Bracken Christina M. , Mizeracka Karolina , McLaughlin Kelly A. 
Published: December 2007

AbstractThe Bone morphogenetic proteins (BMPs) mediate a wide range of diverse cellular behaviors throughout development. Previous studies implicated an important role for BMP signaling during the differentiation of the definitive mammalian kidney, the metanephros. In order to examine whether BMP signaling also plays an important role during the patterning of earlier renal systems, we examined the development of the earliest nephric system, the pronephros. Using the amphibian model system Xenopus laevis, in combination with reagents designed to inhibit BMP signaling during specific stages of nephric development, we revealed an evolutionarily conserved role for this signaling pathway during renal morphogenesis. Our results demonstrate that conditional BMP inhibition after specification of the pronephric anlagen is completed, but prior to the onset of morphogenesis and differentiation of renal tissues, results in the severe malformation of both the pronephric duct and tubules. Importantly, the effects of BMP signaling on the developing nephron during this developmental window are specific, only affecting the developing duct and tubules, but not the glomus. These data, combined with previous studies examining metanephric development in mice, provide further support that BMP functions to mediate morphogenesis of the specified renal field during vertebrate embryogenesis. Specifically, BMP signaling is required for the differentiation of two types of nephric structures, the pronephric tubules and duct. Developmental Dynamics 237:132–144, 2008. © 2007 Wiley‐Liss, Inc.
Multicellular rosette formation during cell ingression in the avian primitive streak
Authors: Wagstaff Laura J. , Bellett Gemma , Mogensen Mette M. , Münsterberg Andrea 
Published: December 2007

AbstractCell movements are a fundamental feature during the development of multi‐cellular organisms. In amniote gastrulation, cells ingress through the primitive streak, which identifies the anterior‐posterior axis of the embryo. We investigated the cytoskeletal architecture during these morphogenetic processes and characterized microtubule organisation in whole chick embryos. This revealed the distribution of cells with polarized and radial microtubule (MT) arrays across different regions of the embryo. Cells in the epiblast usually displayed radial MT‐arrays, while the majority of cells in the primitive streak had polarized MT‐arrays. Within the primitive streak, many cells organized into groups and were arranged in rosette‐like structures with a distinct centre characterized by an accumulation of actin. Extended confocal microscopy and three‐dimensional image reconstruction identified tips of polarized cells that were protruding from the plane of rosettes, usually from the centre. We propose that organization into higher order structures facilitates cell ingression during gastrulation. Developmental Dynamics 237:91–96, 2008. © 2007 Wiley‐Liss, Inc.
Transcriptional profiling of the megabladder mouse: A unique model of bladder dysmorphogenesis
Authors: Singh Sunita , Robinson Melissa , Ismail Ihab , Saha Monalee , Auer Herbert , Kornacker Karl , Robinson Michael L. , Bates Carlton M. , McHugh Kirk M. 
Published: December 2007

AbstractRecent studies in our lab identified a mutant mouse model of obstructive nephropathy designated mgb for megabladder. Homozygotic mgb mice (mgb−/−) develop lower urinary tract obstruction in utero due to a lack of bladder smooth muscle differentiation. This defect is the result of a random transgene insertion/translocation into chromosomes 11 and 16. Transcriptional profiling identified a significantly over‐expressed cluster of gene products located on the translocated fragment of chromosome 16 including urotensin II‐related peptide (Urp), which was shown to be preferentially over‐expressed in developing mgb−/− bladders. Pathway analysis of mgb microarray data indicated dysregulation of at least 60 gene products associated with smooth muscle development. In conclusion, the results of this study indicate that the molecular pathways controlling normal smooth muscle development are severely altered in mgb−/− bladders, and provide the first evidence that Urp may play a critical role in bladder smooth muscle development. Developmental Dynamics 237:170–186, 2008. © 2007 Wiley‐Liss, Inc.
Myocardin expression during avian embryonic heart development requires the endoderm but is independent of BMP signaling
Authors: Warkman Andrew S. , Yatskievych Tatiana A. , Hardy Katharine M. , Krieg Paul A. , Antin Parker B. 
Published: December 2007

AbstractMyocardin, a serum response factor cofactor, plays an important role in regulating heart and smooth muscle development. To investigate myocardin function during early stages of heart development, we isolated the chicken orthologue of myocardin and characterized its expression between Hamburger and Hamilton stages 3 and 15. At stage 4, myocardin transcripts are detected in the lateral and extraembryonic mesoderm, become progressively localized to the precardiac mesoderm and the differentiated myocardium and are also seen in smooth muscle cells of the developing vascular plexus. Surprisingly, myocardin expression within the developing chicken embryo precedes that of the homeodomain transcription factor Nkx2.5. Embryonic dissection studies demonstrate that signals from the endoderm are required for myocardin expression within the precardiac mesoderm. However, unlike Nkx2.5, myocardin expression is not regulated by bone morphogenetic protein (BMP) signaling. These results suggest that initial expression of myocardin in the precardiac mesoderm is regulated by a signaling pathway that is parallel to, and independent of, Nkx2.5 expression. Developmental Dynamics 237:216–221, 2008. © 2007 Wiley‐Liss, Inc.
The macroPARP genes parp‐9 and parp‐14 are developmentally and differentially regulated in mouse tissues
Authors: Hakmé Antoinette , Huber Aline , Dollé Pascal , Schreiber Valérie 
Published: December 2007

AbstractThe macroPARPs Parp‐9 and Parp‐14 are macro domain containing poly(ADP‐ribose) polymerases involved in transcriptional regulation in response to immunoregulatory cytokines. Their genes reside in the same locus (16B3), and the Parp‐9 gene lies head‐to‐head and shares its promoter with the gene encoding its partner, Bbap. Here, we provide a detailed analysis of Parp‐9, Parp‐14, and Bbap expression during mouse development and adulthood. Parp‐9 is developmentally regulated, and prominently expressed in the thymus and specific regions of the brain and gut. In adults, highest expression is maintained in the thymus and intestine. Parp‐14 is more weakly expressed, mainly in the thymus during development and in adulthood. In addition, we show that Bbap is essentially coexpressed with Parp‐9 during development and in adult mouse. However, the different levels of their transcripts detected in the developing brain and gut suggest that Bbap and Parp‐9 display both common and independent tissue‐specific regulations. Developmental Dynamics 237:209–215, 2008. © 2007 Wiley‐Liss, Inc.
SMAD expression in the testis: An insight into BMP regulation of spermatogenesis
Authors: Itman Catherine , Loveland Kate Lakoski 
Published: December 2007

AbstractBone morphogenetic proteins (BMPs), members of the transforming growth factor‐β superfamily, extensively influence events that establish male fertility, affecting germ cells and somatic cells throughout fetal and postnatal life. BMP signals are relayed by SMAD proteins, transcription factors that translocate to the nucleus upon ligand stimulation. We show that BMP signaling in the testis may be regulated by selective expression of BMP‐responsive and inhibitory SMADs, with expression differing between the first wave and adult spermatogenesis. Smad1, Smad5, Smad8, Smad4, Smad6, and Smad7 expression is ubiquitous during testis development but becomes cell‐specific in the adult. Furthermore, regulated SMAD6 protein expression at the onset of spermatogenesis suggests differential responsiveness of spermatogonial subpopulations to ligands. In vitro, immature Sertoli cells and spermatogonia transduce BMP2 and BMP4 signals by means of SMAD1, SMAD5, and SMAD8. Based on these findings, we extrapolate these data to interpret BMP mutant testis phenotypes in terms of SMAD availability for signal transduction. Developmental Dynamics 237:97–111, 2008. © 2007 Wiley‐Liss, Inc.
Suzuki Aryl Coupling Catalysed by Palladium Bis(phosphane) Pincer Complexes Based on Ferrocene; X‐ray Structure Determination of {PdCl[{2,5‐(tBu2PCH2)2C5H2}Fe(C5H5)]}OTf
Authors: Sheloumov Alexey M. , Tundo Pietro , Dolgushin Fedor M. , Koridze Avthandil A. 
Published: December 2007

AbstractPalladium P,C,P pincer complexes PdCl[{2,5‐(R2PCH2)2C5H2}Fe(C5H5)] (1, R = iPr; 2, R = tBu) and {PdCl[{2,5‐(tBu2PCH2)2C5H2}Fe(C5H5)]}OTf (3) catalyse Suzuki aryl coupling under homogeneous conditions as well as in multiphase system (triphase system: organic/Aliquat 336/aqueous solvent); the X‐ray structure of complex 3, in which the iron atom is oxidised, has been determined and compared with that of its neutral precursor 2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
New H‐Bonded Complexes and Their Supramolecular Liquid‐Crystalline Organizations
Authors: Pérez Ana , Gimeno Nélida , Vera Francisco , Ros M. Blanca , Serrano José Luis , De la Fuente M. Rosario 
Published: December 2007

AbstractDifferent approaches to the design of liquid crystals by using H‐bonds were analyzed. A selection of stilbazoles and pyridine compounds, with one or two chelating positions, were used as H‐acceptors in mixtures with carboxylic acids. The noncovalent complexes in question afforded calamitic mesomorphism (N, SmA and SmC) as well as a lamellar mesophase (SmCP). Additionally, the liquid crystalline behaviour of the new 2‐hydroxy‐ and 2‐aminopyridine compounds as pure materials is also discussed. Useful results concerning the design and stability of noncovalent calamitic and bent‐core liquid crystals are reported. To induce the bent‐core liquid crystalline order, the conformational flexibility around the H‐bond must be controlled. The new liquid crystals were characterized by IR spectroscopy, optical microscopy, calorimetry, X‐ray diffraction and dielectric spectroscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reactions of Arenediazonium o‐Benzenedisulfonimides with Aliphatic Triorganoindium Compounds
Authors: Barbero Margherita , Cadamuro Silvano , Dughera Stefano , Ghigo Giovanni 
Published: December 2007

AbstractThe reaction of various arenediazonium o‐benzenedisulfonimides with aliphatic triorganoindium compounds is described. Surprisingly, with triethyl‐ or tributylindium we obtained N‐ethyl‐ or N‐butylanilines, respectively. This is the first case in which, at least formally, the reactive site of a diazonium salt is the nitrogen atom directly bonded to the aromatic ring. In contrast, with trimethylindium we obtained only formaldehyde (aryl)hydrazones. In order to explain the difference between trimethyl‐ and triethylindium we have proposed some reaction mechanisms, supported by detailed density functional (DFT) calculations. The possible role of diazene/hydrazone tautomerism initially assumed was discarded and therefore three mechanisms for the key step (nucleophilic addition of the trialkylindium to the N=N double bond of diazene) were studied. For the favoured mechanism there is a difference in the energy barriers of 2 kcal mol–1 between the reactions with trimethyl‐ and triethylindium. This difference is explained on the basis of the different C–In bond energies in the two organometallics and it is assumed to be enough to explain their different behaviour under the experimental conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Amperometric Biosensor Based on Immobilization Acetylcholinesterase on Manganese Porphyrin Nanoparticles for Detection of Trichlorfon with Flow‐Injection Analysis System
Authors: Li Xiao‐Hua , Xie Zong‐Hong , Min Hong , Xian Yue‐Zhong , Jin Li‐Tong 
Published: December 2007

AbstractA highly sensitive amperometric biosensor for the detection of organophosphate pesticides (OPs) is developed. The biosensor was fabricated by immobilized acetylcholinesterase (AChE) on manganese (III) meso‐tetraphenylporphyrin (MnTPP) nanoparticles (NPs)‐modified glassy carbon (GC) electrode. The MnTPP NPs used in this article were synthesized by mixing solvent techniques. AChE enzyme was immobilized on the MnTPP NPs surface by conjugated with chitosan (CHIT). The electrocatalytic activity of MnTPP NPs led to a greatly improved performance for thiocholine (TCh) product detection. The developed AChE‐CHIT/MnTPPNP/GC biosensor integrated with a flow‐injection analysis (FIA) system was used to monitor trichlorfon (typical OP). A wide linear inhibition response for trichlorfon is observed in the range of 1.0 nM–1.0 mM, corresponding to 10–83% inhibition for AChE with a detection limit of 0.5 nM.
Determination of Total Reduced Thiol Levels in Plasma Using a Bromide Substituted Quinone
Authors: Lobo Grace‐Ann M. , Chitre Sneha A. , Rathod Spandan M. , Smith Robert B. , Leslie Ray , Livingstone Callum , Davis James 
Published: December 2007

AbstractThe exploitation of 2‐bromo‐1,4‐naphthoquinone (NQBr) as a selective redox label for the determination of reduced thiol functionalities (RSH) has been investigated. The system is selective for RSH functionality, giving distinct voltammetric signals for glutathione and cysteine but can also be adapted for broad spectrum thiol detection. Ion chromatographic protocols based on conductimetric detection enable total RSH analysis (protein and monomolecular moieties) within human plasma. Bromide released through the reaction can be easily quantified and integrated within normal IC measurements. The efficacy of the approach has been assessed and the response validated through comparison with the standard colorimetric technique.
Electrochemical Studies of an Iron Porphyrin Immobilized on Nb2O5/SiO2 and Its Application for Simultaneous Determination of Dopamine and Ascorbic Acid Using Multivariate Calibration Methodology
Authors: Skeika Tatiane , Marcovicz Crislaine , Nakagaki Shirley , Fujiwara Sérgio Toshio , Wohnrath Karen , Nagata Noemi , Pessoa Christiana A. 
Published: December 2007

AbstractThis paper shows an application of a first generation porphyrin, FeTPPCl 5,10,25,20‐tetraphenylporphyrin iron(III) chloride (FeTPPCl or FeTPP+) immobilized on a inorganic matrix, SiO2/Nb2O5 (niobium oxide grafted on silica gel surface, designated as SiNb) to the preparation of a carbon paste electrode (CPE). The carbon paste modified with a FeTPP+ immobilized on SiO2/Nb2O5 (SiNb), designated as CPE/SiNb/FeTPP, was applied for simultaneous electrochemical determination of dopamine (DA) and ascorbic acid (AA). Because of the overlapping of the voltammetric peaks of DA and AA, the multivariate calibration methodology based on partial least square regression (PLSR) was proposed. The data pre‐treatment used in this process was mean centering and to choose the principal components number a cross validation procedure was used (leave‐one‐out). Five principal components were necessary to obtain the lowest PRESS (prediction residual error sum of squares). The statistics showed that this model explains approximately 95.2% of the variance from the data set. Using this model, high correlation between actual and predicted concentrations was observed, mainly for higher dopamine (maximum relative error of 8%) and ascorbic acid (maximum relative error of 10%) concentrations. For low analytes concentrations the relative error increases to 35% for AA. Considering the similarity of the voltammetric response of the analytes, the results obtained were satisfactory and showed the promissory capability of the CPE/SiNb/FeTPP coupled multivariate calibration methods for simultaneous voltammetric analysis of DA and AA.
Sol‐Gel Derived Potentiometric Sensor for Determination of Vanadyl Ions
Authors: Arvand Majid , Moghimi Majid , Bagherinia Mohammad A. 
Published: December 2007

AbstractA sol‐gel electrode, based on thiacalix[4]arene as a neutral carrier, was successfully developed for the detection of VO2+ in aqueous solutions. The sol‐gel electrode exhibited linear response with Nernstian slope of 29.3±0.3 mV per decade, within the vanadyl ion concentration ranges 1.0×10−6 – 1.0×10−1 mol dm−3. The sol‐gel electrode shows detection limit of 4.9×10−7 mol dm−3. The influence of membrane composition, the pH of the test solution, and the interfering ions on the electrode performance were investigated. The electrode exhibited good selectivities for a number of alkali, alkaline earth, transition and heavy metal ions. The effect of temperature on the electrode response showed that the temperature higher than 60 °C deteriorates the electrode performance. Application of the electrode for the determination of vanadyl in spiked samples is reported.
Multiple end‐point analysis reveals cisplatin damage tolerance to be a chemoresistance mechanism in a NSCLC model: Implications for predictive testing
Authors: Almeida Gabriela M. , Duarte Tiago L. , Farmer Peter B. , Steward William P. , Jones George D.D. 
Published: December 2007

AbstractSystemic chemotherapy is extensively used in cancer therapy, however, for many treatments' response rates are limited. Furthermore, certain regimens are frequently associated with significant morbidity and occasional mortality. Consequently, when alternative options exist, it is desirable to reserve a particular chemotherapy for those patients whose tumours will respond. Therefore, attention is turning to the development of techniques that could provide predictive information regarding a tumour's particular chemosensitivity, as a means of enhancing patient selection for that specific treatment. One approach has been to focus on measures of DNA damage formation and repair as being potentially predictive of cancer cell chemosensitivity, the premise being that higher levels of induced DNA damage (resulting from the chemotherapeutic agents) and/or deficiencies in DNA damage repair are indicative of greater sensitivity. In the present study we have investigated the Comet assay response of a panel of non‐small cell lung cancer cell lines towards cisplatin and found an inverse correlation between sensitivity and damage formation resulting from this agent. Moreover, an inverse correlation was found between resistance and extent of damage repair. Further analysis of multiple alternate cellular end‐points (including cell cycle analysis, apoptosis and gene expression changes) revealed cisplatin damage tolerance to be a chemoresistance mechanism in this model system. This study highlights damage tolerance mechanisms as potentially confounding factors in attempts to develop predictive tests based on measures of genotoxicity. To address this we would argue that a range of multiple end‐points should be analysed to ascertain the “complete predictive picture”. © 2007 Wiley‐Liss, Inc.