bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Efficient Suzuki–Miyaura Coupling of Heterocyclic Substrates through Rational Reaction Design
Authors: Fleckenstein Christoph A. , Plenio Herbert 
Published: March 2008

AbstractA dicyclohexyl(2‐sulfo‐9‐(3‐(4‐sulfophenyl)propyl)‐9H‐fluoren‐9‐yl)phosphonium salt was synthesized in 64 % overall yield in three steps from simple commercially available starting materials. The highly water‐soluble catalyst obtained from the corresponding phosphine and [Na2PdCl4] enabled the Suzuki coupling of a broad variety of N‐ and S‐heterocyclic substrates. Chloropyridines (‐quinolines) and aryl chlorides were coupled with aryl‐, pyridine‐ or indoleboronic acids in quantitative yields in water/n‐butanol solvent mixtures in the presence of 0.005–0.05 mol % of Pd catalyst at 100 °C, chloropurines were quantitatively Suzuki coupled in the presence of 0.5 mol % of catalyst, and S‐heterocyclic aryl chlorides and aryl‐ or 3‐pyridylboronic acids required 0.01–0.05 mol % Pd catalyst for full conversion. The key to the high activity of the Pd‐phosphine catalyst is the rational design of the reaction parameters (i.e., the presence of water in the reaction mixture, good solubility of reactants and catalyst in n‐butanol/water (3:1), and the electron‐rich and sterically demanding nature of the phosphine ligand).
Double Affinity Amplification of Galectin–Ligand Interactions through Arginine–Arene Interactions: Synthetic, Thermodynamic, and Computational Studies with Aromatic Diamido Thiodigalactosides
Authors: Cumpstey Ian , Salomonsson Emma , Sundin Anders , Leffler Hakon , Nilsson Ulf J. 
Published: March 2008

AbstractA series of aromatic mono‐ or diamido‐thiodigalactoside derivatives were synthesized and studied as ligands for galectin‐1, ‐3, ‐7, ‐8N terminal domain, and ‐9N terminal domain. The affinity determination in vitro with competitive fluorescence‐polarization experiments and thermodynamic analysis by isothermal microcalorimetry provided a coherent picture of structural requirements for arginine–arene interactions in galectin–ligand binding. Computational studies were employed to explain binding preferences for the different galectins. Galectin‐3 formed two almost ideal arene–arginine stacking interactions according to computer modeling and also had the highest affinity for the diamido‐thiodigalactosides (Kd below 50 nM). Site‐directed mutagenesis of galectin‐3 arginines involved in binding corroborated the importance of their interaction with the aromatic diamido‐thiodigalactosides. Furthermore, the arginine mutants revealed distinct differences between free, flexible, and solvent‐exposed arginine side chains and tightly ion‐paired arginine side chains in interactions with aromatic systems.
Dipodal Ferrocene‐Based Adsorbate Molecules for Self‐Assembled Monolayers on Gold
Authors: Weidner Tobias , Ballav Nirmalya , Zharnikov Michael , Priebe Andreas , Long Nicholas J. , Maurer Jörg , Winter Rainer , Rothenberger Alexander , Fenske Dieter , Rother Dag , Bruhn Clemens , Fink Heinrich , Siemeling Ulrich 
Published: March 2008

Abstract1,1′‐Difunctionalised ferrocene derivatives have been studied, which contain groups suitable for chemisorption on gold substrates, namely NC, PR2 as well as a range of sulfur‐containing units like NCS, SR, and thienyl. Thin films on gold have been fabricated from solution with most of these adsorbate species. Film thickness, composition and structure were investigated primarily by X‐ray photoelectron and near‐edge X‐ray absorption fine‐structure spectroscopy. The quality of self‐assembled monolayers fabricated from 1,1′‐diisocyanoferrocene (1) and 1,1′‐diisothiocyanatoferrocene (2) turned out to be superior to that of films based on the other adsorbate species investigated. In addition to the surface coordination behaviour of 1 towards gold substrates, relevant aspects of the molecular coordination chemistry of 1 have also been addressed, including the synthesis and characterisation of [(μ‐1){Cr(CO)5}2], [Ag2(μ‐1)2](NO3)2⋅H2O and [(μ‐1)(AuCl)2]. The crystal structure of the gold complex is governed by aurophilic interactions and can be taken as a model for the arrangement of 1 in self‐assembled monolayers on gold.
Theoretical Investigation of the Reaction Mechanism of the Dinuclear Zinc Enzyme Dihydroorotase
Authors: Liao Rong‐Zhen , Yu Jian‐Guo , Raushel Frank M. , Himo Fahmi 
Published: March 2008

AbstractThe reaction mechanism of the dinuclear zinc enzyme dihydroorotase was investigated by using hybrid density functional theory. This enzyme catalyzes the reversible interconversion of dihydroorotate and carbamoyl aspartate. Two reaction mechanisms in which the important active site residue Asp250 was either protonated or unprotonated were considered. The calculations establish that Asp250 must be unprotonated for the reaction to take place. The bridging hydroxide is shown to be capable of performing nucleophilic attack on the substrate from its bridging position and the role of Znβ is argued to be the stabilization of the tetrahedral intermediate and the transition state leading to it, thereby lowering the barrier for the nucleophilic attack. It is furthermore concluded that the rate‐limiting step is the protonation of the amide nitrogen by Asp250 coupled with CN bond cleavage, which is consistent with previous experimental findings from isotope labeling studies.
Synaptogenesis in the cerebellar cortex: Differential regulation of gephyrin and GABAA receptors at somatic and dendritic synapses of Purkinje cells
Authors: Viltono Laura , Patrizi Annarita , Fritschy Jean‐Marc , Sassoè‐Pognetto Marco 
Published: March 2008

AbstractIn rodent cerebellar cortex, synaptogenesis occurs entirely postnatally, allowing study of the mechanisms of synapse formation in vivo. Here we monitored the clustering of GABAA receptors and the scaffolding protein gephyrin at GABAergic postsynaptic sites during rat cerebellar development. We found that GABAA receptors and gephyrin co‐aggregate at nascent synapses in the molecular and Purkinje cell layers with a similar time course. With few exceptions, gephyrin and GABAA receptor subunits clustered selectively in front of presynaptic boutons expressing the vesicular inhibitory amino acid transporter VIAAT and no ectopic localization of these molecules was observed. Surprisingly, gephyrin clusters outlining the cell body of Purkinje cells were transient, and disappeared rapidly at the end of the second postnatal week. The loss of gephyrin from perisomatic synapses was coincident with a significant reduction in the size of GABAA receptor clusters. Furthermore, these changes were accompanied by a developmental decrease in the size of synaptic appositions, as documented by electron microscopy. These findings suggest that gephyrin takes part in the initial assembly of postsynaptic specializations and reveal an unsuspected heterogeneity in the molecular organization of the postsynaptic apparatus at somatic and dendritic synapses of mature Purkinje cells. J. Comp. Neurol. 508:579–591, 2008. © 2008 Wiley‐Liss, Inc.
Structural Elucidation with NMR Spectroscopy: Practical Strategies for Organic Chemists
Authors: Kwan Eugene E. , Huang Shaw G. 
Published: March 2008

AbstractPractical strategies for the structural elucidation of small organic molecules are described for typical organic chemists. The analysis of an unknown is divided into three stages. First, structural connectivity is deduced from through‐bond correlation experiments. Next, the relative stereochemistry is determined from NOE correlations and coupling constants (both proton–proton and proton–carbon). Finally, the proposed structure is verified by a careful inspection of all of the observed data. Tactics for the management of overlapping peaks, low sample concentrations, and high molecular weights are also described. This approach is illustrated by the step‐by‐step analyses of a simple test compound, menthol, and a complex polycyclic natural product, salvinorin A. Detailed procedures and sample data for menthol are provided as a practical tutorial. This will enable organic chemists to elucidate a wide range of complex structures by using modern NMR spectroscopic experiments.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Modifying Glassy Carbon (GC) Electrodes to Confer Selectivity for the Voltammetric Detection of L‐Cysteine in the Presence of dl‐Homocysteine and Glutathione
Authors: Okumura Leonardo Luiz , Stradiotto Nelson R. , Rees Neil V. , Compton Richard G. 
Published: March 2008

AbstractIn this communication we report a proof of concept study of the use of cyclic voltammetry with a polyeugenol‐modified glassy carbon (GC) electrode to selectively detect L‐cysteine in the presence of both dl‐homocysteine and glutathione in perchloric acid. The formation of a polyeugenol‐modified gold electrode is also reported for the first time.
Electrochemical DNA Hybridization Detection Using DNA Cleavage
Authors: Kwon Dohyoung , Kim Kyuwon , Kwak Juhyoun 
Published: March 2008

AbstractWe report the new method for detection of DNA hybridization using enzymatic cleavage. The strategy is based on that S1 nuclease is able to specifically cleave only single strand DNA, but not double strand DNA. The capture probe DNA, thiolated single strand DNA labeled with electroactive ferrocene group, was immobilized on a gold electrode. After hybridization of target DNA of complementary and noncomplementary sequences, nonhybridized single strand DNA was cleaved using S1 nuclease. The difference of enzymatic cleavage on the modified gold electrode was characterized by cyclic voltammetry and differential pulse voltammetry. We successfully applied this method to the sequence‐selective discrimination between perfectly matched and mismatched target DNA including a single‐base mismatched target DNA. Our method does not require either hybridization indicators or other exogenous signaling molecules which most of the electrochemical hybridization detection systems require.
Determination of Trace Copper by Adsorptive Voltammetry Using a Multiwalled Carbon Nanotube Modified Carbon Paste Electrode
Authors: Deng Peihong , Fei Junjie , Zhang Jun , Li Junan 
Published: March 2008

AbstractA new method for the determination of trace copper was described. A multiwalled carbon nanotube modified carbon paste electrode was prepared and the adsorptive voltammetric behavior of copper‐alizarin red S (ARS) complex at the modified electrode was investigated. By use of the second‐order derivative linear sweep voltammetry, it was found that in 0.04 mol/L acetate buffer solution (pH 4.2) containing 4×10−6 mol/L ARS, when accumulation potential is 0 mV, accumulation time is 60 s and scan rate is 100 mV/s, the complex can be adsorbed on the surface of the electrode, yielding one sensitive reduction peak at −172 mV (vs. SCE). The peak current of the complex is proportional to the concentration of Cu(II) in the range of 2.0×10−11–4.0×10−7 mol L−1 with a detection limit (S/N=3) of 8.0×10−12 mol/L (4 min accumulation). The proposed method was successfully applied to the determination of copper in biological samples with satisfactory results, the recoveries were found to be 96%–102%.
Determination of Caffeic Acid in Red Wine by Voltammetric Method
Authors: da Silva Luiz Fernando , Ramos Stradiotto Nelson , Oliveira Herenilton Paulino 
Published: March 2008

AbstractThe electrochemical oxidation of 3,4‐dihydroxycinnamic acid, caffeic acid, leads to a stable electroactive poly(caffeic acid) thin film containing quinone moiety on a preactivated glassy polymeric carbon electrode. The properties of the deposited films as well as the stability study under different experimental conditions were investigated. Taking advantage of the electrochemical behavior, an analytical method based on differential pulse voltammetry for determination of caffeic acid in red wine was proposed.
Lead(II) Potentiometric Sensor Based on 1,4,8,11‐Tetrathiacyclotetradecane Neutral Carrier and Lipophilic Additives
Authors: Elmosallamy Mohamed A. F. , Fathy Ahmed M. , Ghoneim Ahmed K. 
Published: March 2008

AbstractA potentiometric sensor for lead(II) ions based on the use of 1,4,8,11‐tetrathiacyclotetradecane (TTCTD) as a neutral ionophore and potassium tetrakis‐(p‐chlorophenyl)borate as a lipophilic additive in plasticized PVC membranes is developed. The sensor exhibits linear potentiometric response towards lead(II) ions over the concentration range of 1.0×10−5–1.0×10−2 mol L−1 with a Nernstian slope of 29.9 mV decade−1 and a lower limit of detection of 2.2×10−6 mol L−1 Pb(II) ions over the pH range of 3–6.5. Sensor membrane without a lipophilic additive displays poor response. The sensor shows high selectivity for Pb(II) over a wide variety of alkali, alkaline earth and transition metal ions. The sensor shows long life span, high reproducibility, fast response and long term stability. Validation of the method by measuring the lower limit of detection, lower limit of linear range, accuracy, precision and sensitivity reveals good performance characteristics of the proposed sensor. The developed sensor is successfully applied to direct determination of lead(II) in real samples. The sensor is also used as an indicator electrode for the potentiometric titration of Pb(II) with EDTA and potassium chromate. The results obtained agree fairly well with data obtained by AAS.
HPV16 E629‐38‐specific T cells kill cervical carcinoma cells despite partial evasion of T‐cell effector function
Authors: Thomas Karen J. , Smith Kelly L. , Youde Sarah J. , Evans Mererid , Fiander Alison N. , Borysiewicz Leszek K. , Man Stephen 
Published: March 2008

AbstractPersistent human papillomavirus type 16 (HPV16) infection is associated with the development of more than 50% of cervical cancers. The HPV16 E6 and E7 oncoproteins are constitutively expressed in cervical carcinomas and are attractive targets for cytotoxic T lymphocyte (CTL)‐based immunotherapy. However, cervical carcinomas may possess multiple evasion mechanisms for HPV16 E6/E7‐specific CTL. In this study, we investigated whether HPV16+ cervical carcinoma cell lines (CaCxCL) could evade all effector functions of HPV16 E629‐38‐specific T cells. Such CD8+ T cells were detected in the blood (4/10) or invaded lymph node (1/1) of cervical cancer patients using HLA‐A*0201/HPV16 E629‐38 tetramers after in vitro stimulation. T cells cultured from 3 different donors killed HPV16 E629‐38 peptide‐pulsed target cells but not HPV16+ CaCxCL in 51Cr release assays. The absence of killing correlated with limited T‐cell degranulation against CaCxCL, but this was not due to antigen processing defects per se; CaCxCL could induce specific T‐cell release of IFN‐γ and TNF‐α, and CaCxCL could be killed in longer cytotoxicity assays (>20 hr). Interestingly, the ‘slow’ killing of CaCxCL could be partially inhibited by concanamycin A, a known perforin inhibitor. The results suggest that CaCxCL was only partially activating T cells, but this was still sufficient for slow killing. Overall, our results highlight the need to examine multiple T‐cell effector functions in the context of endogenous antigen presentation by tumour cells. In this study, testing for cytotoxicity using short‐term assays only would have ruled out a candidate epitope for immunotherapy. © 2008 Wiley‐Liss, Inc.
Evaluation of the psychometrics properties of the alarm distress baby scale among 122 Brazilian children
Authors: Lopes Simone C. Facuri , Ricas Janete , Mancini Marisa Cotta 
Published: March 2008

AbstractThe Alarm Distress Baby Scale (ADBB) aims at assessing infant withdrawal behavior. A previous validation study revealed acceptable reliability and validity indices. The present study investigated the psychometric properties of the scale in a larger sample from a culturally different population. Pediatricians evaluated the behavior of 122 infants, 2 and 19 months old, using the ADBB during routine physical consultation. Four investigators (two pediatricians and two nurses not specialized in pediatric care) examined video recordings of the evaluations. Results showed good interrater reliability coefficients among pediatricians and poor correlation when all professionals were grouped together. Test–retest reliability revealed good intraexaminer agreement (r = 0.91). The pediatricians' evaluation using the ADBB was compared with a psychiatric examination to investigate the scale's criterion validity. The cutoff point of 5 provided the best clinical validity (sensitivity of 79%, specificity of 81%). Results from construct validity showed that the scale had three dimensions. Comparison of the factor solution with other construct validity studies of the same instrument revealed similarities and differences. Results suggest that the ADBB may be a useful screening instrument to detect signs of psychiatric alterations related to withdrawal behavior in primary care services, and it is likely to provide consistent information.
DICAM, a novel dual immunoglobulin domain containing cell adhesion molecule interacts with αvβ3 integrin
Authors: Jung Youn‐Kwan , Jin Jung‐Suk , Jeong Jae‐Hwan , Kim Hyun‐Nam , Park Na‐Rae , Choi Je‐Yong 
Published: March 2008

AbstractImmunoglobulin (Ig) superfamily members are abundant with diverse functions including cell adhesion in various tissues. Here, we identified and characterized a novel adhesion molecule that belongs to the CTX protein family and named as DICAM (Dual Ig domain containing cell adhesion molecule). DICAM is a type I transmembrane protein with two V‐type Ig domains in the extracellular region and a short cytoplasmic tail of 442 amino acids. DICAM is found to be expressed ubiquitously in various organs and cell lines. Subcellular localization of DICAM was observed in the cell–cell contact region and nucleus of cultured epithelial cells. Cell–cell contact region was colocalized with tight junction protein, ZO‐1. The DICAM increased MDCK cell adhesion to 60% levels of fibronectin. DICAM mediated cell adhesion was specific for the αvβ3 integrin; other integrins, α2, α5, β1, α2β1, α5β1, were not involved in cell adhesion. In identifying the interacting domain of DICAM with αvβ3, the Ig domain 2 showed higher cell adhesion activity than that of Ig domain 1. Although RGD motif in Ig domain 2 was engaged in cell adhesion, it was not participated in DICAM‐αvβ3 mediated cell adhesion. Furthermore, differentially expressing DICAM stable cells showed well correlated cell to cell adhesion capability with integrin β3‐overexpressing cells. Collectively, these results indicate that DICAM, a novel dual Ig domain containing adhesion molecule, mediates cell adhesion via αvβ3 integrin. J. Cell. Physiol. 216: 603–614, 2008, © 2008 Wiley‐Liss, Inc.
Plasminogen‐induced aggregation of PANC‐1 cells requires conversion to plasmin and is inhibited by endogenous plasminogen activator inhibitor‐1
Authors: Deshet Naamit , Lupu‐Meiri Monica , Espinoza Ingrid , Fili Oded , Shapira Yuval , Lupu Ruth , Gershengorn Marvin C. , Oron Yoram 
Published: March 2008

AbstractPANC‐1 cells express proteinase‐activated receptors (PARs)‐1, ‐2, and respond to their activation by transient elevation of cytosolic [Ca2+] and accelerated aggregation (Wei et al., 2006, J Cell Physiol 206:322–328). We studied the effect of plasminogen (PGN), an inactive precursor of the PAR‐1‐activating protease, plasmin (PN) on aggregation of pancreatic adenocarcinoma (PDAC) cells. A single dose of PGN time‐ and dose‐dependently promoted PANC‐1 cells aggregation in serum‐free medium, while PN did not. PANC‐1 cells express urokinase plasminogen activator (uPA), which continuously converted PGN to PN. This activity and PGN‐induced aggregation were inhibited by the uPA inhibitor amiloride. PGN‐induced aggregation was also inhibited by α‐antiplasmin and by the PN inhibitor ε‐aminocaproic acid (EACA). Direct assay of uPA activity revealed very low rate, markedly enhanced in the presence of PGN. Moreover, in PGN activator inhibitor 1‐deficient PANC‐1 cells, uPA activity and PGN‐induced aggregation were markedly potentiated. Two additional human PDAC cell lines, MiaPaCa and Colo347, were assayed for PGN‐induced aggregation. Both cell lines responded by aggregation and exhibited PGN‐enhanced uPA activity. We hypothesized that the continuous conversion of PGN to PN by endogenous uPA is limited by PN's degradation and negatively controlled by endogenously produced PAI‐1. Indeed, we found that PANC‐1 cells inactivate PN with t1/2 of approximately 7 h, while the continuous addition of PN promoted aggregation. Our data suggest that PANC‐1 cells possess intrinsic, PAI‐1‐sensitive mechanism for promotion of aggregation and differentiation by prolonged exposure to PGN and, possibly, additional precursors of PARs agonists. J. Cell. Physiol. 216: 632–639, 2008, © 2008 Wiley‐Liss, Inc.
Cardiac hemodynamics of the rainbow trout (Oncorhynchus mykiss) using simultaneous Doppler echocardiography and electrocardiography
Authors: Cotter Paul A. , Han Adrienne J. , Everson James J. , Rodnick Kenneth J. 
Published: March 2008

AbstractUsing Doppler echocardiography and electrocardiography, we characterized cardiac hemodynamics, timing, and electromechanical function, and examined the effects of ventricular hypertrophy on systolic function in anesthetized rainbow trout. Atrial filling (DSA), ventricular filling (DAV), and ventricular ejection (DVB) accounted for 40–77, 13–27, and 22–41% of the cardiac cycle, respectively. Ventricular ejection occurred entirely during atrial filling and ended by the time the QT interval was 80% (SD=9%) completed. Sinoatrial (SA) flow was of longer duration (0.53±0.08 sec, mean±SD) and lower velocity (32±8 cm sec−1) than corresponding atrioventricular (AV, 0.19±0.02 sec; 87±8 cm sec−1) and ventriculobulbar (VB, 0.30±0.05 sec; 63±20 cm sec−1) values. Despite a wide range of heart masses, atrioventricular and VB valve dimensions were identical (∼5.5 mm2). Ventricle mass (MV), but not relative ventricle mass (RVM), and cardiac cycle length were positively correlated (r2=0.57, P<0.001); thus, all time‐dependent electrical/mechanical measures of cardiac function were significantly related to MV, but not RVM. All rate‐corrected (c) electromechanical event durations (except cDSA) and the systolic function index (cPEP (pre‐ejection period)/DVB) were independent of RVM, suggesting the maintenance of cardiac functional capabilities across maturation stages (males) and different ventricle sizes (males and females). In summary, we define fundamental electrical and mechanical properties of the in vivo teleost myocardium under anesthesia, and report the maintenance of systolic function over a wide range of heart sizes for both sexes and maturation state of males. We also suggest that the short duration of ventricular emptying relative to the QT interval may provide a novel mechanism to adjust stroke volume and cardiac output in teleosts. J. Exp. Zool. 309A:243–254, 2008. © 2008 Wiley‐Liss, Inc.