bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acyclic Diene Metathesis with a Monomer from Renewable Resources: Control of Molecular Weight and One‐Step Preparation of Block Copolymers
Authors: Rybak Anastasiya , Meier Michael A. R. 
Published: May 2008

AbstractThe preparation of a long‐chain aliphatic α,ω‐diene from plant oil derivatives and its subsequent polymerization through acyclic diene metathesis (ADMET) is described. The ADMET bulk polymerization of the thus‐obtained monomer, undecyl undecenoate, was investigated and optimized by applying ruthenium‐based metathesis catalysts from Grubbs and Hoveyda–Grubbs, leading to high‐molecular‐weight polyesters. Moreover, by applying different amounts of methyl 10‐undecenoate as a chain stopper in this ADMET step growth polymerization, the molecular weight of the resulting polyester could be tuned in a range from approximately 10 to 45 kDa. Finally, the application of a poly(ethylene glycol) methyl ether acrylate as the chain stopper led to the preparation of ABA triblock copolymers in a one‐step, one‐pot procedure.
Observation of calcium microdomains at the uropod of living morphologically polarized human neutrophils using flash lamp‐based fluorescence microscopy
Authors: Clark Andrea J. , Petty Howard R. 
Published: May 2008

AbstractThe present study outlines improved strategies for ratiometric imaging of cell calcium using a flash lamp‐based excitation method and its application to neutrophil polarization. A brief (∼6 μs) and intense flash was used to excite the Fluo‐4 and Fura Red calcium dye combination in morphologically polarized human neutrophils. These illumination conditions do not allow the dye or calcium ions to diffuse significant distances during the exposure period. Buffer conditions such as pH, pyruvate concentration, and glucose levels were adjusted to more faithfully replicate these parameters in sepsis patients. Fluorescence images at both dyes' emission wavelengths were simultaneously collected using a Dual‐View apparatus and an ICCD camera. The ratiometric images, when viewed as single frames or averaged image stacks, clearly demonstrated high calcium probe ratios at the uropod and comparatively low ratios at the cell body that were not evident using conventional imaging methods with longer exposure times. Calcium signaling at the uropod is likely associated with cytoskeletal remodeling during cell motility. © 2008 International Society for Advancement of Cytometry
Sequential univariate gating approach to study the effects of erythropoietin in murine bone marrow
Authors: Achuthanandam Ram , Quinn John , Capocasale Renold J. , Bugelski Peter J. , Hrebien Leonid , Kam Moshe 
Published: May 2008

AbstractAnalysis of multicolor flow cytometric data is traditionally based on the judgment of an expert, generally time consuming, sometimes incomplete and often subjective in nature. In this article, we investigate another statistical method using a Sequential Univariate Gating (SUG) algorithm to identify regions of interest between two groups of multivariate flow cytometric data. The metric used to differentiate between the groups of univariate distributions in SUG is the Kolmogorov‐Smirnov distance (D) statistic. The performance of the algorithm is evaluated by applying it to a known three‐color data set looking at activation of CD4+ and CD8+ lymphocytes with anti‐CD3 antibody treatment and comparing the results to the expert analysis. The algorithm is then applied to a four‐color data set used to study the effects of recombinant human erythropoietin (rHuEPO) on several murine bone marrow populations. SUG was used to identify regions of interest in the data and results compared to expert analysis and the current state‐of‐the‐art statistical method, Frequency Difference Gating (FDG). Cluster analysis was then performed to identify subpopulations responding differently to rHuEPO. Expert analysis, SUG and FDG identified regions in the data that showed activation of CD4+ and CD8+ lymphocytes with anti‐CD3 treatment. In the rHuEPO treated data sets, the expert and SUG identified a dose responsive expansion of only the erythroid precursor population. In contrast, FDG resulted in identification of regions of interest both in the erythroid precursors as well as in other bone marrow populations. Clustering within the regions of interest defined by SUG resulted in identification of four subpopulations of erythroid precursors that are morphologically distinct and show a differential response to rHuEPO treatment. Greatest expansion is seen in the basophilic and poly/orthochromic erythroblast populations with treatment. Identification of populations of interest can be performed using SUG in less subjective, time efficient, biologically interpretable manner that corroborates with the expert analysis. The results suggest that basophilic erythroblasts cells or their immediate precursors are an important target for the effects of rHuEPO in murine bone marrow. The MATLAB implementation of the method described in the article, both experimental data and other supplemental materials are freely available at http://web.mac.com/acidrap18. © 2008 International Society for Advancement of Cytometry
Complexes of Yb3+ with EDTA and CDTA – Molecular and Electronic Structure
Authors: Janicki Rafał , Starynowicz Przemysław , Mondry Anna 
Published: May 2008

AbstractTwo Yb3+ compounds, [C(NH2)3]2[Yb(EDTA)(H2O)2]ClO4·6H2O and [C(NH2)3][Yb(CDTA)(H2O)2]·4H2O, where EDTA is the ethylenediaminetetraacetate anion and CDTA is the trans‐1,2‐diaminecyclohexane‐N,N,N′,N′‐tetraacetate anion, were obtained and their crystal structures and spectroscopic properties were determined. In both compounds, the coordination geometries of the eight‐coordinate Yb3+ ion are very similar. In each case, the inner sphere of the metal ion consists of four carboxyl oxygen atoms, two nitrogen atoms and two water molecules. The complexes were characterized by UV/Vis/NIR absorption at different temperatures and IR spectroscopy. The spectroscopic results revealed high sensitivity of the electronic 4f13 configuration upon minor changes in the coordination geometry around the Yb3+ ion. These data also demonstrate that species present in solutions of Yb3+–EDTA are similar to those found in the crystal, whereas in solutions of Yb3+–CDTA an equilibrium between at least two different forms exists. For the Yb3+–EDTA complex in solution and in the crystalline state, a charge‐transfer transition was detected. Theoretical calculations revealed its complicated (Yb → ligand and ligand → Yb) character.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Donor‐Functionalised N‐Heterocyclic Carbene Complexes of Group 9 and 10 Metals in Catalysis: Trends and Directions
Authors: Normand Adrien T. , Cavell Kingsley J. 
Published: May 2008

AbstractThis review focuses on the latest advances in homogeneous catalysis with donor‐functionalised (donor = C, N, O, S or P) N‐heterocyclic carbene complexes of group 9 and 10 metals. The applications of such complexes to C–C coupling reactions, alkyne and ketone hydrosilylation, olefin polymerisation, transfer hydrogenation, asymmetric hydrogenation and other catalysed reactions are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Kinetic parameter determination of vegetable oil oxidation under Rancimat test conditions
Authors: Farhoosh Reza , Niazmand Razieh , Rezaei Mitra , Sarabi Mahboobe 
Published: May 2008

AbstractIn this research, five different vegetable oils were oxidized at four different temperatures (373, 383, 393, and 403 K) under Rancimat test conditions. An increasing rate of oxidation could be observed as temperature increased. The natural logarithms of the kinetic rate constant (k value) varied linearly with respect to temperature, with the temperature coefficients (TCoeff) ranging from 6.95×10–2 to 7.40× 10–2 K–1 for the vegetable oils. On the basis of the Arrhenius equation and the activated complex theory, frequency factors (A), activation energies (Ea), Q10 numbers, activation enthalpies (ΔH++), and activation entropies (ΔS++) for oxidative stability of the vegetable oils were calculated. The A, Ea, Q10, ΔH++, and ΔS++ values for the vegetable oils ranged from 6.38×103 to 28.03×103 h–1, from 86.86 to 92.42 kJ/mol, from 2.08 to 2.18, from 83.64 to 89.20 kJ/mol, and from –116.66 to –104.35 J/mol K, respectively.
Metathesis as a versatile tool in oleochemistry
Authors: Rybak Anastasiya , Fokou Patrice A. , Meier Michael A. R. 
Published: May 2008

AbstractOlefin metathesis, awarded with the Nobel Prize in Chemistry 2005 for Chauvin, Grubbs and Schrock, has emerged as a powerful tool for organic as well as polymer chemistry. In oleochemistry, this reaction is well known and has been applied for many decades. Examples include the functionalization of the double bonds of different oleochemicals or the (direct) polymerization of plant oils via metathesis. More recent developments, particularly the development of better and more robust catalysts, allow for highly efficient cross‐metathesis reactions opening new possibilities for the direct introduction of chemical functionalities. Within this contribution, the development of metathesis in oleochemistry will be discussed, covering self‐metathesis as well as more recent developments in the field of cross‐metathesis that lead to desired platform chemicals.
Stable Triazenes Derived from 2‐Alkylaminonaphthalenes and 5‐Nitrobenzo[c]‐1,2‐thiazole‐3‐diazonium Hydrogensulfate
Authors: Přikryl Josef , Macháček Vladimír , Jansa Petr , Svobodová Markéta , Růžička Aleš , Nachtigall Petr , Černý Michal 
Published: May 2008

AbstractA calculation using the DFT method confirmed that the extraordinary stability of the triazenes formed by an azo coupling reaction of 5‐nitrobenzo[c]‐1,2‐thiazole‐3‐diazonium with primary or secondary aromatic amines is caused by the fact that these substances are protonated at the heterocyclic nitrogen atom and not at the nitrogen atom of the triazene grouping –N=N–N(R)Ar. Stable triazenes are also formed by reaction of 5‐nitrobenzo[c]‐1,2‐thiazole‐3‐diazonium with 2‐alkylaminonaphthalenes. In the cases of the azo coupling reaction with 2‐methylamino‐ and 2‐ethylaminonaphthalene, the content of triazenes is almost 50 % in the product mixture with the isomeric azo compounds. The structures of the triazenes were confirmed by X‐ray analysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Determination of trace levels of benzodiazepine in urine using capillary electrochromatography‐time of flight mass spectrometry
Authors: Blas Maximilien , McCord Bruce R. 
Published: May 2008

AbstractThis paper details a method for the separation and determination of ten benzodiazepines in urine using CEC‐MS(TOF) and an hexyl acrylate‐based porous monolith. The TOF mass spectrometer provides an exact mass of protonated benzodiazepines to three decimal places (1–6 ppm). This high selectivity along with the CEC separation, provides an effective method for the identification of benzodiazepines. Linearity is satisfactory for all compounds in the concentration range of 25–500 ng/mL for lorazepam and 12.5–500 ng/mL for the others. The RSDs are between 1.4–2.3% for retention times and 1.1–9.2% for relative areas. Using the monolithic stationary phase, a preconcentration step is achievable and permits an 75–140‐fold improvement in sensitivity. This strategy permits the quantification of these drugs down to 1 ng/mL in urine. This method was used for the analysis of benzodiazepines in spiked urine samples.
The role of post‐translational modifications for learning and memory formation
Authors: Sunyer Berta , Diao Weifei , Lubec Gert 
Published: May 2008

AbstractLearning and memory depend on molecular mechanisms involving the protein machinery. Recent evidence proposes that post‐translational modifications (PTMs) play a major role in these cognitive processes. PTMs including phosphorylation of serine, threonine, and tyrosine are already well‐documented to play a role for synaptic plasticity of the brain, neurotransmitter release, vesicle trafficking and synaptosomal or synaptosomal‐associated proteins are substrates of a series of specific protein kinases and their counterparts, protein phosphatases. But protein phosphorylation is only one out of many possible PTMs and first work shows a role of palmitoylation as well as glycosylation for proteins involved in memory formation. Recent technology may now allow reliable detection and even quantification of PTMs of proteins involved in the cognitive system. This will contribute to the understanding of mechanisms for learning and memory formation at the chemical level and has to complement determination of protein levels and indeed determination of protein expression per se generates limited information. The many other PTMs expected including protein nitrosylation and alkylation will even represent targets for pharmacological interventions but in turn increase the complexity of the system. Nevertheless, determination of the presence and the function of PTMs is mandatory and promising cognitive research at the protein chemical level.
Capillary electrophoresis‐mass spectrometry – a fast and reliable tool for the monitoring of milk adulteration
Authors: Műller Lukáš , Barták Petr , Bednář Petr , Fryšová Iveta , Ševčík Juraj , Lemr Karel 
Published: May 2008

AbstractThe development of a rapid, simple and accurate analytical method aimed at the detection and quantification of bovine milk in either ovine or caprine milk samples by means of CE‐MS analyses of whey proteins with high‐ionic strength and presence of acidic running buffer is described. The high‐ionic strength buffer was used in order to minimize the problems with the adsorption of the proteins onto the fused‐silica capillary wall. The acidic running electrolyte, pH 1.9, was used to support the production of positive ions in electrospray. Highly linear dependences of the ratio of the sum of non‐bovine β‐lactoglobulins (ovine or caprine) to the total β‐lactoglobulins in milk mixture (bovine plus ovine or bovine plus caprine) vs. the volume percentage of added bovine milk in ovine (or caprine) milk were obtained. This technique allowed the fast and reliable evaluation of milk adulteration. The amount of bovine milk added into the “non‐bovine” ones can be well within the concentration range of 5–95%.
Analysis of immune complexes by capillary electrophoresis
Authors: Shihabi Zak K. 
Published: May 2008

AbstractA simple method for immune complexes (IC) analysis by CE is described. This method combines the ease of precipitation of the IC by polyethylene glycol with the separation power of CE. The advantage of this method is a better quantitation of the IC, since it corrects and eliminates the interferences from other serum proteins. It also reveals the composition (monoclonality) of the precipitate. Three types of IC have been detected in this method: monoclonal, polyclonal and mixed (mono‐polyclonal) IC. Furthermore, the method is rapid and simple.
Combined capillary electrophoresis and DNA‐fluorescence in situ hybridization for rapid molecular identification of Salmonella Typhimurium in mixed culture
Authors: Lantz Andrew W. , Brehm‐Stecher Byron F. , Armstrong Daniel W. 
Published: May 2008

AbstractCE, long a staple in analytical chemistry for molecular separations, has recently been adapted for separating heterogeneous mixtures of microbial cells based on intrinsic differences in cell morphology and surface charge. In this application, CE enables effective separations of both relatively broad categories of cells, as well as of more similar cell types. As a phenotypic approach, CE may be less applicable to certain populations, including those comprised of pleiomorphic cells or chain‐forming cells, where differences in cell size, shape, or chain length may lead to broad, “unfocusable” distributions in cell surface charge. At the other end of the spectrum, closely related species having similar surface charge profiles may not be separable via CE alone. Successful combination of microbial CE with a compatible method for generating cell‐specific signals could address these limitations, increasing the diagnostic power of this approach. Fluorescence in situ hybridization (FISH) is a rapid molecular technique for fluorescence‐based labeling of whole target cells. In this work, we combined a simple CE‐based presence/absence test with FISH to develop a bacterial detection assay having an additional “layer” of molecular specificity. Using this approach, we were able to differentiate Salmonella Typhimurium from Escherichia coli in mixed populations via CE. Both hybridizations and CE run times were short (10–15 min), bacterial populations were highly focused (∼2–3 s peak width) and there was no need for a posthybridization wash step. As few as three injected cells of S. Typhimurium were detected against a background of ∼300 injected E. coli cells, suggesting the possibility for single‐cell detection of pathogens using this technique. This proof of concept study highlights the potential of CE‐FISH as a promising new tool for molecular detection of specific bacterial cells within mixtures of closely related, physiologically inseparable populations.
Downregulation of two isoforms of ubiquitin carboxyl‐terminal hydrolase isozyme L1 correlates with high metastatic potentials of human SN12C renal cell carcinoma cell clones
Authors: Tanaka Toshiyuki , Kuramitsu Yasuhiro , Fujimoto Masanori , Naito Seiji , Oka Masaaki , Nakamura Kazuyuki 
Published: May 2008

AbstractProteomic differential display analysis was performed on human renal cell carcinoma cell SN12C clones having different metastatic potentials by using 2‐DE and LC‐MS/MS. The SN12C cell clones were SN12C parent cell line, SN12C‐clone 2, SN12C‐clone 4, and SN12C‐PM6. The SN12C parent cell line was established from an HRCC surgical specimen. SN12C‐clone 4 has lower, and SN12C‐clone 2 and SN12C‐PM6 have higher metastatic potential than SN12C parent cells. We found eight protein spots whose expression level was different between low metastatic clones and high metastatic clones. The protein expression of three appeared to be higher in high metastatic clones than low metastatic clones, and that of other five protein spots appeared to be lower in high metastatic clones than low metastatic clones. These spots were selected, digested and analyzed by LC‐MS/MS analysis, and they were identified by peptide sequencing tag. In high metastatic potential clones, two isoforms of ubiquitin carboxyl‐terminal hydrolase isozyme L1 (UCH‐L1) were downregulated. These results suggest that UCH‐L1 expression seems to be associated with the metastatic potential of HRCC SN12C cell clones.
Electrophoretic evidence for the presence of structural isoforms specific for the IgG2 isotype
Authors: Guo Amy , Han Mei , Martinez Theresa , Ketchem Randal R. , Novick Shawn , Jochheim Claudia , Balland Alain 
Published: May 2008

AbstractRecombinant monoclonal antibodies of therapeutic interest were analyzed by a nonreduced CE‐SDS (nrCE‐SDS) method developed for the evaluation of size‐based variants. We found that immunoglobulins analyzed by this technique exhibited different behavior depending on their subclasses. Under nrCE‐SDS conditions, IgG1 molecules were separated in a well‐resolved, single peak, whereas IgG2 molecules were consistently separated as a doublet. Investigation of these isoforms showed that they were structurally different, and that the difference was not caused by cell culture condition, glycosylation structure, or recombinant expression system. Commercially available IgG2 affinity‐purified from human plasma also showed the presence of structural isoforms. The structural isoforms remained present under pH‐ and temperature‐stressed conditions. Application of a mild cysteine/cystine redox potential converted the main peak doublet into a single peak, indicating that these isoforms were disulfide bond‐related species. Bioactivity measured before and after application of a redox potential gave similar values, indicating that the structural isoforms have comparable potency. The nrCE‐SDS technique described here demonstrated a unique capability to resolve IgGs, leading to the discovery of novel structural isoforms specific to the IgG2 isotype.
Live‐cell imaging reveals sustained centromere binding of CENP‐T via CENP‐A and CENP‐B
Authors: Hellwig D. , Münch S. , Orthaus S. , Hoischen C. , Hemmerich P. , Diekmann S. 
Published: May 2008

AbstractAt the centromere, a network of proteins, the kinetochore, assembles in order to grant correct chromatin segregation. In this study the dynamics and molecular interactions of the inner kinetochore protein CENP‐T were analyzed employing a variety of fluorescence microscopy techniques in living human cells. Acceptor‐bleaching FRET indicates that CENP‐T directly associates with CENP‐A and CENP‐B. CENP‐T exchange into centromeres is restricted to the S‐phase of the cell cycle as revealed by FRAP, suggesting a coreplicational loading mechanism, as we have recently also demonstrated for CENP‐I. These properties make CENP‐T one of the basic inner kinetochore proteins with most further proteins binding downstream, suggesting a fundamental role of CENP‐T in kinetochore function. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Human osteoclast formation and activity on a xenogenous bone mineral
Authors: Perrotti Vittoria , Nicholls Brian M. , Horton Michael A. , Piattelli Adriano 
Published: May 2008

AbstractTo date, the majority of studies on bone substitute materials have investigated their regenerative properties; however, little is known about their resorption processes, forasmuch as it is believed that the ideal biomaterial for bone regeneration must be completely resorbable. This study is aimed at defining the in vitro resorption potential of human osteoclasts (OCLs) on a xenogenous bone mineral (XBM). Peripheral blood mononuclear cells from healthy volunteers were used to generate OCLs in vitro in the presence of macrophage colony stimulating factor and receptor activator of NF‐κB ligand on bovine bone slices and XBM. By using morphologic and biochemical methods, we observed that OCL formation occurred on XBM and these cells were positive for the major OCL markers. Regarding OCL activity, resorption pits were detected on XBM by reflection and confocal microscopy. However, biochemical analysis revealed that collagen degradation at day 14 and 21 was significantly lower in XBM supernatants when compared to bovine bone, suggesting that XBM underwent a much slower resorption over time. These findings demonstrate that OCLs are generated on, attach to, and resorb XBM though more slowly than native bone, and suggest that cultured human OCLs could be used as a model for comparing resorption rates of bone substitute materials. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009