bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chiral resolution of melatoninergic ligands by EKC using highly sulfated CDs
Authors: Lipka Emmanuelle , Danel Cécile , Orhan Hervé , Bonte Jean‐Paul , Vaccher Claude 
Published: October 2007

AbstractEKC methods for the enantiomeric resolutions of melatoninergic ligands were developed using anionic CDs (highly S‐α‐CD, highly S‐β‐CD, and highly S‐γ‐CD) as chiral selectors at acidic pH 2.5. The optimization of the various operational parameters (nature and concentration of the CD, phosphate buffer concentration, addition of organic modifiers in the BGE, and temperature) allows baseline enantioresolutions (superior to 2) in short analysis times (inferior to 7 min) for all studied analytes. Some analytical characteristics of the optimal method were then studied for each analyte: repeatability, linearity, and LOD and LOQ. Lastly, determination of the apparent binding constants for the 18 complexes formed between the six analytes and the three CDs led us to rationalize the complexation mechanisms.
Improved solubilization of surface proteins from Listeria monocytogenes for 2‐DE
Authors: Mujahid Sana , Pechan Tibor , Wang Chinling 
Published: October 2007

AbstractSolubilization of bacterial surface (cell wall and membrane‐associated) proteins for 2‐DE is challenging, particularly in the case of Gram‐positive bacteria. This is primarily due to strong protein association with the cell wall peptidoglycan and protein hydrophobicity. We solubilized surface proteins for 2‐DE from the Gram‐positive pathogen Listeria monocytogenes using mutanolysin, which digests cell wall peptidoglycan, and one of three different mixtures of zwitterionic detergent and chaotropes: (i) CHAPS/urea, (ii) amidosulfobetaine‐14 (ASB‐14)/urea/thiourea (iii) N‐decyl‐N,N'‐dimethyl‐3‐ammonio‐1‐propanesulfonate/urea/thiourea. Cell lysis with mutanolysin followed by solubilization with ASB‐14/urea/thiourea gave the highest overall protein yield with the best 2‐DE resolution. Protein spot identification by MALDI‐TOF/TOF‐MS analysis revealed 29 characterized surface proteins of L. monocytogenes, 17 of which have not previously been reported on the surface proteome map. This is the first report describing the successful solubilization and 2‐DE of L. monocytogenes proteins bound to the cell surface via an LPXTG motif or by a hydrophobic tail. The increase in surface proteome coverage obtained by mutanolysin and ASB‐14/urea/thiourea solubilization suggests the utility of this method for future analytical and comparative studies of surface proteins from Listeria, and possibly other Gram‐positive bacteria, using 2‐DE proteomic analysis. An updated 2‐DE reference map of L. monocytogenes surface proteins is presented.
Enantioseparation of phenothiazines in CD‐modified CZE using single isomer sulfated CD as a chiral selector
Authors: Liao Wei‐Ssu , Lin Chen‐Hsing , Chen Chih‐Yu , Kuo Chia‐Ming , Liu Yu‐Chih , Wu Jong‐Chang , Lin Ching‐Erh 
Published: October 2007

AbstractEnantioseparations of five chiral phenothiazines in CD‐modified CZE using the single isomer sulfate‐substituted β‐CD (heptakis(2,3‐dihydroxy‐6‐O‐sulfo)‐β‐CD, SI‐S‐β‐CD) and dual CD systems consisting of SI‐S‐β‐CD and a neutral CD as chiral selectors in a citrate buffer at pH 3.0 were investigated. The results indicate that SI‐S‐β‐CD is an excellent chiral selector for enantioseparation of promethazine. The enantiomers of trimeprazine were well separated, while those of ethopropazine could also be baseline‐resolved with SI‐S‐β‐CD. With dual CD systems, especially with hydroxypropyl‐β‐CD (HP‐β‐CD) as neutral CD, the enantioselectivity of thioridazine and ethopropazine was considerably enhanced. Effective enantioseparation of phenothiazines, except for methotrimeprazine, could thus be favorably and simultaneously achieved. Moreover, reversal of the enantiomer migration order of ethopropazine and thioridazine occurred by varying the concentration of γ‐CD in the presence of SI‐S‐β‐CD. These phenomena may be attributable to the opposite effects of sulfated β‐CD and γ‐CD on the mobility of the enantiomers of ethopropazine and of thioridazine. Comparative studies on the enantioseparations of phenothiazines with single CD and dual CD systems containing SI‐S‐β‐CD and randomly sulfate‐substituted β‐CD (MI‐S‐β‐CD) were made.
CE‐based noncompetitive immunoassay for immunoglobulin G in bovine colostrum products
Authors: Zhao Jin , Ding Xiaojing , Wang Xinyu , Wang Qian , Wang Zhi 
Published: October 2007

AbstractA CE‐based noncompetitive immunoassay for IgG in bovine colostrum products was established. FITC‐labeled protein G (FITC‐PrG) was tagged through noncovalent bindings to the Fc region of the mouse monoclonal antibovine IgG (Ab). The FITC‐PrG, Ab, and IgG formed a sandwiched immunocomplex FITC‐PrG‐Ab‐IgG under optimal incubation conditions. The immunocomplex was separated and analyzed by CZE with LIF detection in less than 2 min in an uncoated fused‐silica capillary. Addition of PEG 20 000 (PEG 20M) in the running buffer significantly suppressed analyte adsorption and thus improved the reproducibility and the resolution. The precision of the method was 5.1% (n = 7). A linear relationship was established for the IgG concentration in the range of 1–5 mg/L with a linear correlation coefficient (r = 0.9917). The LOD was 0.1 mg/L (S/N = 3). The method was successfully applied for the determination of IgG in bovine colostrum products and satisfactory results were achieved.
High‐throughput determination of glutathione and reactive oxygen species in single cells based on fluorescence images in a microchannel
Authors: Gao Ning , Li Lu , Shi Zhikun , Zhang Xiaoli , Jin Wenrui 
Published: October 2007

AbstractA novel high‐throughput method is presented based on fluorescence images of cells in a microchannel for determination of glutathione (GSH) and reactive oxygen species (ROS) inside single cells. We first present a method to determine GSH and ROS separately, in which GSH in cells is derivatized by 2,3‐naphthalenedicarboxaldehyde (NDA), and intracellular ROS is labeled using dihydrorhodamine 123. The cells with either fluorescent derivatized GSH or fluorescent labeled ROS are introduced into a microchannel and fluorescence images of every moving cell in the microchannel are taken continuously using a highly sensitive thermoelectrically cooled electron‐multiplying CCD. The fluorescence intensities of the images correspond to the masses of GSH or ROS. An average detection rate of 80–120 cells/min is achieved. We then propose a method for simultaneously determining GSH and ROS, in which ROS is first labeled in the cells. The labeled cells are then introduced into the whole channel and allowed to immobilize onto the glass substrate. The fluorescence images of all the cells in the channel are taken. NDA is then introduced into the channel to derivatize the GSH in the immobilized cells, and fluorescence images of all cells are taken again. An average analysis rate of ˜20 cells/min is achieved. The masses of GSH and ROS in the single cells can be obtained from the fluorescence intensities of the images using their calibration curves. Since the cells are not lysed, there is no problem with adsorption of biological macromolecules and cellular debris on the channel wall, so that channel treatment, necessary in usual single‐cell analysis techniques using CE and microchip electrophoresis, is no longer necessary. For single global cells, this method can also be used to determine the concentrations of ROS and GSH, which has not been reported previously. The concentrations of ROS and GSH in single global cells can be calculated from the determined masses and the cell volume (derived from the diameter of the round fluorescence image of the derivatized GSH). For gastric cancer cells, the concentrations of GSH and ROS are in the range 0.35×10‐3–1.3×10‐3 mol/L and 0.77×10‐6–1.5×10‐6 mol/L, respectively.
RNA analysis by MEKC with LIF detection
Authors: Cornelius Michael G. , Schmeiser Heinz H. 
Published: October 2007

AbstractWe have developed and validated a procedure of high sensitivity for the analysis of RNA. The procedure is based on the separation and detection of the 5'‐monophosphates of ribonucleosides selectively conjugated with 4,4‐difluoro‐5,7‐dimethyl‐4‐bora‐3a,4a‐diaza‐s‐indacene‐3‐propionyl ethylene diamine hydrochloride (BODIPY FL EDA) at the 5'‐phosphate group using CE with LIF. BODIPY conjugates of the four common ribonucleoside‐5'‐monophosphates were prepared and subjected to CE‐LIF to serve as standard compounds for peak assignment and to develop separation conditions. After digestion of RNA or oligoribonucleotides to 5'‐monophosphates by nuclease P1 and fluorescence labeling BODIPY conjugates were detected and resolved by CE‐LIF without further purification steps. Comparative CE‐LIF analyses with DNA digested to deoxyribonucleoside‐5'‐monophosphates showed that the assay is equally efficient and sensitive for RNA analysis. Conditions to determine the modified ribonucleosides inosine, xanthosine, pseudouridine and 2'‐O‐methyladenosine were also established. The limits of detection were in the range of 80–200 pM. After calibrating the assay with oligoribonucleotides, pseudouridine was quantified in total RNA of Drosophila, human liver, human kidney and t‐RNA of Saccharomyces cerevisiae. These studies demonstrate good potential of fluorescence labeling of ribonucleoside‐5'‐monophosphates with BODIPY FL EDA and detection by CE‐LIF to determine RNA composition with high accuracy and sensitivity.
Preparative alkaline urea gradient PAGE: Application to purification of extraordinarily‐stable disulfide‐linked homodimer of human growth hormone
Authors: Grigorian Alexei L. , Bustamante Juan J. , Muñoz Jesus , Aguilar Roberto M. , Martinez Andrew O. , Haro Luis S. 
Published: October 2007

AbstractThe 40–60 pituitary human growth hormone (hGH) isoforms are so similar in their physico‐chemical properties (charge, size, hydrophobicity) that the limited resolutions of chromatographic separation methodologies have not permitted most of them to be isolated. However, application of high‐resolution preparative alkaline urea gradient PAGE has facilitated isolation of a disulfide‐linked mercaptoethanol‐resistant (MER) 45 kDa hGH dimer. Human pituitary extracts were separated by Sephadex G‐100 chromatography under alkaline conditions. Pooled fractions containing MER‐45 kDa hGH, as determined by SDS‐PAGE, were then separated by Sephadex G‐100 chromatography under acidic conditions followed by diethylaminoethyl (DEAE) anion‐exchange chromatography. Pooled DEAE fractions containing MER‐45 kDa hGH and other hGH isoforms were then separated by preparative electrophoresis in an alkaline polyacrylamide gradient (5–20%) slab gel containing 8 M urea into five distinct protein zones. One electroeluted zone contained pure MER‐45 kDa hGH. The dimeric hGH isoform was immunoreactive at low concentrations (effective dose to produce 50% response (ED50) ± S.E. = 58 ± 5.00 pM) in a hGH radioimmunoassay, similar to that of standard monomeric hGH (ED50 ± S.E. = 22.93 ± 3.90 pM), indicating that is was conformationally intact. Alkaline urea gradient PAGE is a valuable tool for preparative separation of structurally similar proteins such as isoforms of the hGH family.
Analysis of dideoxyadenosine triphosphate by CE with fluorescence detection. I. Derivatization through the phosphate group
Authors: Mallampati Swapna , Van Aerschot Arthur , Hoogmartens Jos , Van Schepdael Ann 
Published: October 2007

AbstractA CZE method was developed, which separates 2′,3′‐dideoxyadenosine‐5′‐triphosphate (ddATP) from other metabolites and endogenous nucleotides at high concentrations (20–200 μg/mL) to allow UV detection. To enhance sensitivity, fluorescence detection which requires prior derivatization of compounds was examined. Precapillary derivatization of ddATP in the presence of N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride (EDAC) with dansyl ethylenediamine (dansyl EDA) was faster and stable compared to that of 4,4‐difluoro‐5,7‐dimethyl‐4‐bora‐3a,4a‐diaza‐s‐indacene‐3‐propionyl ethylenediamine (BODIPY FL EDA). Reaction conditions, reagent concentrations and detection parameters were optimized and highest derivatization efficiency was achieved in 0.1 M 1‐methylimidazole buffer (pH 8.0) with 140 mM EDAC in 1‐methylimidazole buffer and 30 mM dansyl EDA in DMF for 90 min at 60°C. Dansyl EDA derivatives of ddATP, 2′‐deoxyadenosine‐5′‐triphosphate (dATP) and ATP were comigrating with the CZE method; therefore, a MEKC method was developed and optimized for repeatable separations. Upon dansylation, sensitivity of ddATP with fluorescence detection (LOQ = 12 ng/mL) was 160 times higher than UV detection (LOQ = 1.9 μg/mL).
A simple method to remove contaminating salt from IPG strips prior to IEF
Authors: Heppelmann Carrie J. , Benson Linda M. , Bergen H. Robert 
Published: October 2007

AbstractIn this study, Saccharomyces cerevisiae yeast lysate is used to demonstrate how a simple wash procedure can improve IEF of IPG strips passively rehydrated in the presence of NaCl. By performing three 10 min washes after IPG strip rehydration and before IEF, corresponding second‐dimensional gels from strips containing NaCl look similar to control strips while the second‐dimensional gels of unwashed strips contains streaks and spaces devoid of protein. Up to 500 mM NaCl was added to the yeast lysate and successfully focused following this wash regime. Protein loss due to the washes was determined to be minimal by comparing replicates of washed and unwashed strips and analyzing the densities of their corresponding second‐dimensional gel spots. In the event of unknown salt contamination, indicated by low voltage during focusing, it is possible to stop focusing, wash the strips, and then continue focusing with acceptable second dimension results.
Electrokinetic injection of DNA from gel micropads: Basis for coupling polony technology with CE separation
Authors: Kosobokova Olga , Gavrilov Dmitri N. , Khozikov Vyacheslav , Stepukhovich Andrey , Tsupryk Andriy , Pan'kov Sergey , Somova Olga , Abanshin Nikolai , Gudkov Georgiy , Tcherevishnik Marina , Gorfinkel Vera 
Published: October 2007

AbstractWe propose a novel method for electrokinetic injection of DNA samples into capillaries from nanoliter gel micropads, deposited on glass slides, which are coated with electroconducting film. Theoretical and experimental proof is presented for the proposed method. The method allows efficient and highly precise injection without physical contact between the gel pad and the capillary. Read length of more than 700 bp at Q20 has been reproducibly demonstrated in fused‐silica capillaries using the proposed injection technique. Based on the obtained results we discuss a novel DNA sequencing system which combines DNA amplification and cycle sequencing in arrays of subnanoliter gel micropads and high‐throughput electrophoretic separation in monolith multicapillary arrays.
Transient response in steel moment frames caused by brittle connection fracture
Authors: Rodgers Janise E. , Mahin Stephen A. 
Published: October 2007

AbstractBrittle fractures occurring at the beam–column connections of welded steel moment frames, such as those observed following the Mw 6.7 1994 Northridge earthquake, result in sudden decreases in connection strength and stiffness. These changes lead to various types of transient dynamic behavior at the local and global levels. The effects on global acceleration include highly transient, high‐frequency waveforms that occur immediately following fracture and decay quickly. The theoretical basis for the occurrence of these transient waveforms is examined and their presence in structural analysis results is demonstrated. Results from shaking table experiments on a simple steel moment frame with fracturing connections show that transient accelerations are consistently observed following fracture. These experiments and analyses show that, due to their short duration, the transient acceleration waveforms do not cause any sudden changes in the global lateral displacement response of typical building structures. Therefore, these global acceleration transients have relatively benign effects on overall system behavior despite their relatively large amplitudes. Copyright © 2007 John Wiley & Sons, Ltd.
Understanding the accuracy of statistical haplotype inference with sequence data of known phase
Authors: Andrés Aida M. , Clark Andrew G. , Shimmin Lawrence , Boerwinkle Eric , Sing Charles F. , Hixson James E. 
Published: October 2007

AbstractStatistical methods for haplotype inference from multi‐site genotypes of unrelated individuals have important application in association studies and population genetics. Understanding the factors that affect the accuracy of this inference is important, but their assessment has been restricted by the limited availability of biological data with known phase. We created hybrid cell lines monosomic for human chromosome 19 and produced single‐chromosome complete sequences of a 48 kb genomic region in 39 individuals of African American (AA) and European American (EA) origin. We employ these phase‐known genotypes and coalescent simulations to assess the accuracy of statistical haplotype reconstruction by several algorithms. Accuracy of phase inference was considerably low in our biological data even for regions as short as 25–50 kb, suggesting that caution is needed when analyzing reconstructed haplotypes. Moreover, the reliability of estimated confidence in phase inference is not high enough to allow for a reliable incorporation of site‐specific uncertainty information in subsequent analyses. We show that, in samples of certain mixed ancestry (AA and EA populations), the most accurate haplotypes are probably obtained when increasing sample size by considering the largest, pooled sample, despite the hypothetical problems associated with pooling across those heterogeneous samples. Strategies to improve confidence in reconstructed haplotypes, and realistic alternatives to the analysis of inferred haplotypes, are discussed. Genet. Epidemiol. © 2007 Wiley‐Liss, Inc.
Pleiotropy and principal components of heritability combine to increase power for association analysis
Authors: Klei Lambertus , Luca Diana , Devlin B. , Roeder Kathryn 
Published: October 2007

AbstractWhen many correlated traits are measured the potential exists to discover the coordinated control of these traits via genotyped polymorphisms. A common statistical approach to this problem involves assessing the relationship between each phenotype and each single nucleotide polymorphism (SNP) individually (PHN); and taking a Bonferroni correction for the effective number of independent tests conducted. Alternatively, one can apply a dimension reduction technique, such as estimation of principal components, and test for an association with the principal components of the phenotypes (PCP) rather than the individual phenotypes. Building on the work of Lange and colleagues we develop an alternative method based on the principal component of heritability (PCH). For each SNP the PCH approach reduces the phenotypes to a single trait that has a higher heritability than any other linear combination of the phenotypes. As a result, the association between a SNP and derived trait is often easier to detect than an association with any of the individual phenotypes or the PCP. When applied to unrelated subjects, PCH has a drawback. For each SNP it is necessary to estimate the vector of loadings that maximize the heritability over all phenotypes. We develop a method of iterated sample splitting that uses one portion of the data for training and the remainder for testing. This cross‐validation approach maintains the type I error control and yet utilizes the data efficiently, resulting in a powerful test for association. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
A genomic imprinting test for ordinal traits in pedigree data
Authors: Feng Rui , Zhang Heping 
Published: October 2007

AbstractGenomic imprinting can lead maternally and paternally derived alleles with identical nucleotide sequences to function differently and has been found to affect the complex inheritance of a variety of human disorders. Statistical methods that differentiate the parent‐of‐origin effects on human diseases are available for binary traits and continuous traits. However, numerous common diseases are measured on discrete ordinal scales. Imprinting may also contribute to the complex genetic basis of these traits. In a previous study, we proposed a latent variable model and developed computationally efficient score statistic to test linkage of ordinal traits for any size pedigree while adjusting for non‐genetic covariates. In this study, we extend the latent variable model to incorporate parent‐of‐origin information and further develop a score statistic for testing the imprinting effect in linkage analysis. We evaluated the properties of our test statistic using simulations. We then applied our method to the Collaborative Study on the Genetics of Alcoholism and found a novel locus on chromosome 18 that shows a strong signal for imprinting. In addition, we identified two loci on chromosomes 3 and 4 significantly (p<0.0001) linked with alcoholism. Genet. Epidemiol. 2008. © 2007 Wiley‐Liss, Inc.
Increased GAD67 mRNA expression in cerebellar interneurons in autism: Implications for Purkinje cell dysfunction
Authors: Yip Jane , Soghomonian Jean‐Jacques , Blatt Gene J. 
Published: October 2007

AbstractIt has been widely reported that in autism, the number of Purkinje cells (PCs) is decreased, and recently, decreased expression of glutamic acid decarboxylase 67 (GAD67) mRNA in Purkinje cells also has been observed. However, the autism literature has not addressed key GABAergic inputs into Purkinje cells. Inhibitory basket and stellate cell interneurons in the molecular layer of the cerebellar cortex provide direct key GABAergic input into Purkinje cells and could potently influence the output of Purkinje cells to deep cerebellar nuclei. We investigated the capacity for interneuronal synthesis of gamma‐amino butyric acid (GABA) in both types of interneurons that innervate the remaining PCs in the posterolateral cerebellar hemisphere in autism. The level of GAD67 mRNA, one of the isoforms of the key synthesizing enzymes for GABA, was quantified at the single‐cell level using in situ hybridization in brains of autistic and aged‐matched controls. The National Institutes of Health imaging system showed that expression of GAD67 mRNA in basket cells was significantly up‐regulated, by 28%, in eight autistic brains compared with that in eight control brains (mean ± SEM pixels per cell, 1.03 ± 0.05 versus 0.69 ± 0.05, respectively; P < 0.0001 by independent t test). Stellate cells showed a trend toward a small increase in GAD67 mRNA levels, but this did not reach significance. The results suggest that basket cells likely provide increased GABAergic feed‐forward inhibition to PCs in autism, directly affecting PC output to target neurons in the dentate nucleus and potentially disrupting its modulatory role in key motor and/or cognitive behaviors in autistic individuals. © 2007 Wiley‐Liss, Inc.