bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of the acridine orange–protein–surfactant system for protein estimation based on aromatic ring stacking effect of sodium dodecyl benzene sulphonate
Authors: wang Fei , Yang Jinghe , Wu Xia , Wang Xiaobo , Guo Changying , Jia Zhen 
Published: April 2006

AbstractThe fluorescence of acridine orange (AO) is greatly quenched by the anionic surfactant sodium dodecyl benzene sulphonate (SDBS), but when protein is added into the AO–SDBS system, the fluorescence intensity of the latter is enhanced again. Based on this, a new fluorimetric method of determination of protein was developed. Under optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of protein, such as bovine serum albumin (BSA), human serum albumin (HSA) and egg albumin (EA), over a wide range with detection limits at the 10−9 g/mL level. This method has been satisfactorily used for the determination of protein in samples. We compared results using 280 nm and 490 nm excitation wavelengths and the mechanism of the assay. Copyright © 2006 John Wiley & Sons, Ltd.
Inhibition and enhancement by organic compounds of luminol–KIO4–H2O2 chemiluminescence
Authors: Xu Hong , Duan Chun‐Feng , Lai Chun‐Ze , Lian Mei , Zhang Zhi‐Feng , Liu Li‐Juan , Cui Hua 
Published: April 2006

AbstractThe effects of 36 organic compounds on luminol–KIO4–H2O2 chemiluminescence (CL) were studied. It was found that most of the tested compounds could inhibit or enhance the CL intensity. The activities of such inhibitors or enhancers were related to the pH of the CL system and the number and position of functional groups such as –OH and –NH2 on aromatic rings. The mechanism of the CL inhibition and enhancement was considered. Based on the CL inhibition or enhancement, the possibility of analytical applications was explored. The results demonstrated that numerous compounds were detectable at the ng/mL level using the CL system. Copyright © 2006 John Wiley & Sons, Ltd.
A comparison of the presumptive luminol test for blood with four non‐chemiluminescent forensic techniques
Authors: Webb Joanne L. , Creamer Jonathan I. , Quickenden Terence I. 
Published: April 2006

AbstractPresumptive blood detection tests are used by forensic investigators to detect trace amounts of blood or to investigate suspicious stains. Through the years, a number of articles have been published on the popular techniques of the day. However, there is no single paper that critiques and compares the five most common presumptive blood detection tests currently in use: luminol, phenolphthalein (Kastle–Meyer), leucomalachite green, Hemastix® and the forensic light source. The present authors aimed to compare the above techniques with regard to their sensitivity, ease of use and safety. The luminol test was determined to be the most sensitive of the techniques, while Hemastix® is a suitable alternative when the luminol test is not appropriate. Copyright © 2006 John Wiley & Sons, Ltd.
Azobenzene as Conformational Switch in Model Peptides
Authors: Renner Christian , Moroder Luis 
Published: April 2006

AbstractThe photoinduced isomerization of azobenzene between the extended (trans) and compact (cis) conformations is reversibly triggered by light of two differing wavelengths. The resulting changes in molecular geometry have been extensively utilized to photoswitch transformations in chemical species reversibly for applications in optoelectronic devises as well as to photocontrol conformational states in (bio)polymers. The high isomerization yield, remarkable photostability and ultrafast kinetics (few ps) of azobenzene are well suited for the design of small, defined model systems that allow detailed folding studies to be carried out both experimentally and theoretically on the same molecules. In our and other laboratories such systems were recently obtained with cyclic peptides of defined conformational preferences as well as with α‐helical and β‐hairpin peptides. These should, by comparison of simulation and experiment, permit an assessment and improvement of the theoretical description on the one hand and a detailed interpretation of the ultrafast conformational dynamics on the other. The phototriggered changes in conformational states lead to concurrent changes in biophysical properties that can be exploited in the photocontrol of biochemical and biological events, as exemplarily discussed with redox‐active cyclic bis‐cysteinyl peptides and receptor ligands.
FTIR Studies of Iron–Carbonyl Intermediates in Allylic Alcohol Photoisomerization
Authors: Chong Thiam Seong , Tan Sze Tat , Fan Wai Yip 
Published: April 2006

AbstractThe 532 or 355 nm laser‐induced photoisomerization of allylic alcohols to aldehydes catalyzed by [Fe3(CO)12] or [Fe(CO)4PPh3] in hexane was investigated. The Fourier transform infrared (FTIR) absorption spectra of iron–carbonyl intermediate species such as [Fe(CO)5], [Fe(CO)4(R‐C3H4OH)], and more importantly the π‐allyl iron–carbonyl hydride species [FeH(CO)3(R‐C3H3OH)] (R=H, Me, Ph) were recorded during the catalytic process using [Fe3(CO)12] as the catalytic precursor. When [Fe(CO)4PPh3] was photolyzed with 355 nm, [FeH(CO)3(R‐C3H3OH)] was also generated indicating the common occurrence of the species in these two systems. The π‐allyl hydride species is long believed to be a key intermediates and its detection here lends support to the π‐allyl mechanism of the photoisomerization of allyl alcohols.
Pyrimidinyl Nitronyl Nitroxides
Authors: Brough Peter , Pécaut Jacques , Rassat André , Rey Paul 
Published: April 2006

AbstractThe chemistry of 2,2,4,4‐substituted pentane derivatives has been investigated with the aim of providing a flexible and versatile synthetic route to pyrimidinyl nitronyl nitroxides, in which the bis‐N‐oxy fragment is incorporated in a six‐membered ring. The synthesis of 2,4‐diamino‐2,4‐dimethylpentane and 2,4‐bis(hydroxylamino)‐2,4‐dimethylpentane, convenient precursors of these nitroxides, is described and full characterization of a series of pyrimidinyl nitronyl nitroxides is reported, along with a preliminary study of their coordination properties.
Synthesis and Structural Model of an α(2,6)‐Sialyl‐T Glycosylated MUC1 Eicosapeptide under Physiological Conditions
Authors: Dziadek Sebastian , Griesinger Christian , Kunz Horst , Reinscheid Uwe M. 
Published: April 2006

AbstractTo study the effect of O‐glycosylation on the conformational propensities of a peptide backbone, a 20‐residue peptide (GSTAPPAHGVTSAPDTRPAP) representing the full length tandem repeat sequence of the human mucin MUC1 and its analogue glycosylated with the (2,6)‐sialyl‐T antigen on Thr11, were prepared and investigated by NMR and molecular modeling. The peptides contain both the GVTSAP sequence, which is an effective substrate for GalNAc transferases, and the PDTRP fragment, a known epitope recognized by several anti‐MUC1 monoclonal antibodies. It has been shown that glycosylation of threonine in the GVTSAP sequence is a prerequisite for subsequent glycosylation of the serine at GVTSAP. Furthermore, carbohydrates serve as additional epitopes for MUC1 antibodies. Investigation of the solution structure of the sialyl‐T glycoeicosapeptide in a H2O/D2O mixture (9:1) under physiological conditions (25 °C and pH 6.5) revealed that the attachment of the saccharide side‐chain affects the conformational equilibrium of the peptide backbone near the glycosylated Thr11 residue. For the GVTSA region, an extended, rod‐like secondary structure was found by restrained molecular dynamics simulation. The APDTR region formed a turn structure which is more flexibly organized. Taken together, the joined sequence GVTSAPDTR represents the largest structural model of MUC1 derived glycopeptides analyzed so far.
Identification of organ‐specific T cell populations by analysis of multiparameter flow cytometry data using DNA‐chip analysis software
Authors: Hofmann Matthias , Zerwes Hans‐Günter 
Published: April 2006

AbstractBackground:The analysis of cells from multiple experimental groups by multiparameter flow cytometry leads to the generation of complex data sets, for which adequate analysis tools are not commonly available. We report here that software designed for transcriptomics applications can be used in multiparameter flow cytometry.Methods:Lymphocytes isolated from nine different mouse organs were stained and subjected to 10‐parameter flow cytometry. The resulting data set contained 594 different T cell subsets per organ per mouse and was organized into a so‐called flow cytometry array (FCA).Results:Computation of a hierarchical tree revealed that lymph nodes and spleen were populated by similar T cell subsets, while T cells from peripheral organs displayed a diverse subset composition. Furthermore, organ‐specific T cell subsets were identified.Conclusions:This new FCA concept in flow cytomics proved to be a valuable tool for the fast and unbiased analysis of complex multiparameter flow cytometry data sets. It can be used for assessing disease progression and therapeutic intervention, and for the association of disease‐related biomarkers on the protein level. © 2006 International Society for Analytical Cytology
Redox‐Active Coordination Polymers from Esterified Hexavanadate Units and Divalent Metal Cations
Authors: Han Jong Woo , Hardcastle Kenneth I. , Hill Craig L. 
Published: April 2006

AbstractThe redox‐active bis(pyridyl)‐capped hexavanadate [V6O13{(OCH2)3C(4‐CONHC5H4N)}2]2– (1) reacts with divalent first‐row transition‐metal cations (MnII, CoII, NiII, or ZnII) to yield crystalline linear zwitterionic coordination polymers (1M). The zwitterionic coordination chains are connected to each other by hydrogen bonds to form a 3D network. Microporous channels are formed along the packing axes of the 2D networks. All four compounds exhibit almost identical cell parameters, space group (P) and crystal morphology. The materials have been characterized by X‐ray crystallography, 1H and 51V NMR, IR, UV/Vis, elemental analysis, and TGA. All compounds 1M are reversibly reduced by chemical reductants such as phenylhydrazine and NaBH4 in CCl4 in which the hexavanadates are insoluble. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Study on pharmacokinetics and tissue distribution of norvancomycin in rats by CE with electrochemical detection
Authors: Zhou Tianshu , Wu Fang , Shi Guoyue , Wang Aifang , Hu Qin , Wang Xiaochun , Fang Yuzhi 
Published: April 2006

AbstractIn this paper, we developed a sensitive and simple method to study the pharmacokinetics and tissue distribution of norvancomycin (NVCM) in experimental animals by using CE with electrochemical detection. Pharmacokinetics investigation was performed by the collection of blood samples at timed intervals following administration of NVCM. Pharmacokinetic parameters were calculated by the 3P87 pharmacokinetic program. The elimination half‐life of NVCM was 42.4742 min with a clearance rate of 0.0233 mL·kg−1·min−1. Additionally, drug distribution was studied by measuring the NVCM levels in kidney, lung, stomach, intestine, spleen, heart, liver, and cerebrum. Electrophoresis conditions such as buffer solution, working potential, separation voltage, and sampling time were also discussed. The linear range was from 0.8 to 540 μg/mL with a correlation coefficient of 0.9991. The detection limit was 0.3 μg/mL. This method was for the first time applied to study the pharmacokinetics and tissue distributions of NVCM in experimental animals.
Free‐solution electrophoresis of DNA modified with drag‐tags at both ends
Authors: Meagher Robert J. , McCormick Laurette C. , Haynes Russell D. , Won Jong‐In , Lin Jennifer S. , Slater Gary W. , Barron Annelise E. 
Published: April 2006

AbstractIn end‐labeled free‐solution electrophoresis (ELFSE), DNA molecules are labeled with a frictional modifier or “drag‐tag”, allowing their size‐based electrophoretic separation in free solution. Among the interesting observations from early work with dsDNA using streptavidin as a drag‐tag was that the drag induced by including a streptavidin label at both ends was significantly more than double that from a single streptavidin (Heller, C. et al.., J. Chromatogr. A 1998, 806, 113–121). This finding was assumed to be in error, and subsequent work focused on experiments in which only a single drag‐tag is appended to one end of the DNA molecule. Recent theoretical work (McCormick, L. C., Slater, G. W., Electrophoresis 2005, 26, 1659–1667) has examined the contribution of end‐effects to the free‐solution electrophoretic mobility of charged‐uncharged polymer conjugates, reopening the question of enhanced drag from placing a drag‐tag at both ends. In this study, this effect is investigated experimentally, using custom‐synthesized ssDNA oligonucleotides allowing the attachment of drag‐tags to one or both ends, as well as dsDNA PCR products generated with primers appropriate for the attachment of drag‐tags at one or both ends. A range of sizes of drag‐tags are used, including synthetic polypeptoid drag‐tags as well as genetically engineered protein polymer drag‐tags. The enhanced drag arising from labeling both ends has been confirmed, with 6–9% additional drag for the ssDNA and 10–23% additional drag for the dsDNA arising from labeling both ends than would be expected from simply doubling the size of the drag‐tag at one end. The experimental results for ssDNA labeled at both ends are compared to the predictions of the recent theory of end‐effects, with reasonably good quantitative agreement. These experimental findings demonstrate the feasibility of enhancing ELFSE separations by labeling both ends of the DNA molecule, leading to greater resolving power and a wider range of applications for this technique.
Nonaqueous versus aqueous capillary electrophoresis of α‐helical polypeptides: Effect of secondary structure on separation selectivity
Authors: Psurek Arndt , Feuerstein Sophie , Willbold Dieter , Scriba Gerhard K. E. 
Published: April 2006

AbstractThe CE separation of α‐helical polypeptides composed of 14–31 amino acid residues has been investigated using aqueous and nonaqueous BGEs. The running buffers were optimized with respect to pH. Generally, higher separation selectivities were observed in nonaqueous electrolytes. This may be explained by a change in the secondary structure when changing from water to organic solvents. Circular dichroism spectra revealed a significant increase in helical structures in methanol‐based buffers compared to aqueous buffers. This change in secondary structure of the polypeptides contributed primarily to the different separation selectivity observed in aqueous CE and NACE. For small oligopeptides of two to five amino acid residues no significant effect of the solvent was observed in some cases while in other cases a reversal of the migration order occurred when changing from aqueous to nonaqueous buffers. As these peptides cannot adopt secondary structures the effect may be attributed to a shift of the pKa values in organic solvents compared to water.
Breast cancer proteomics by laser capture microdissection, sample pooling, 54‐cm IPG IEF, and differential iodine radioisotope detection
Authors: Neubauer Hans , Clare Susan E. , Kurek Raffael , Fehm Tanja , Wallwiener Diethelm , Sotlar Karl , Nordheim Alfred , Wozny Wojciech , Schwall Gerhard P. , Poznanović Slobodan , Sastri Chaturvedula , Hunzinger Christian , Stegmann Werner , Schrattenholz André , Cahill Michael A. 
Published: April 2006

AbstractThe presence of progesterone receptor (PR) in estrogen receptor (ER)‐positive breast cancer is associated with a good prognosis, and indicates that tumors are likely to respond to tamoxifen. However, ER+/PR− tumors respond less well. To reveal the potential molecular mechanism of this phenomenon, we sought to identify differential protein abundances between invasive ductal carcinoma cells from cryopreserved ER+/PR+ and ER+/PR− mammary tumor specimens. Because current proteomics methods are hampered in the examination of most primary human tumor samples by the extreme tissue heterogeneity, we used laser capture microdissection (LCM) to isolate tumor cells and developed a sample pooling strategy to analyze small sample protein lysates. Proteins from LCM‐harvested tumors were pooled into four sub‐pools from each condition of three tumors/sub‐pool, and proteins from respective paired sub‐pools were co‐electrophoresed by 2‐DE using 54‐cm IEF over pH 4–9. Abundance ratios were accurately quantified by a differential multiplex radioactive ProteoTope method at low attomole levels (∼3.6 &&mu;;g protein per labeling reaction, <180 ng per multiplex protein sample per 54‐cm gel). Applying this approach, differentially displayed proteins were identified by MS using comigrating non‐radioactively labeled tumor proteins. They include decreased cytochrome b5 and transgelin, and more abundant CRABP‐II, cyclophilin A, Neudesin, and hemoglobin in ER+/PR+ tumors versus ER+/PR−providing a possible explanation for differential susceptibility against tamoxifen as a result of deregulated cytochrome b5‐dependent metabolism. This study demonstrates the potential of ProteoTope and LCM to enable extremely sensitive and precise differential analyses from well‐defined primary clinical specimen.
Sample pretreatment on a microchip with an integrated electrospray emitter
Authors: Lindberg Peter , Dahlin Andreas P. , Bergström Sara K. , Thorslund Sara , Andrén Per E. , Nikolajeff Fredrik , Bergquist Jonas 
Published: April 2006

AbstractThis study presents a microbead‐packed PDMS microchip with an integrated electrospray emitter for sample pretreatment prior to sheathless ESI‐MS. We prove the concept of analytical functions integrated onto a cm‐sized area of a single bulk material. The microchip consists of two PDMS substrates replicated from SU‐8 fabricated silicon wafer masters, bonded together after oxidation by corona discharge treatment. The channel within the microchip contains a grid structure that was used to trap 5 µm hypercross‐linked polystyrene beads. The beads acted as a medium for sample desalting and enrichment. Electrical contact for the sheathless ESI process was achieved by coating the integrated emitter with conductive graphite powder after applying a thin layer of PDMS as glue. The coating as well as the bond of the PDMS structures showed excellent durability. A continuous spray was obtained from the microchip for over 800 h in a long‐term electrospray stability experiment. Desalting and enrichment of neuropeptides from a physiological salt solution was successful by loading the sample onto the packed beads, followed by a washing and an eluting step. The results were obtained and evaluated using a TOF MS. An LOD of approximately 20 fmol (loaded onto the beads) for angiotensin II was obtained from a sample of neuropeptides dissolved in physiological salt solution.
Biomarker discovery by CE‐MS enables sequence analysis via MS/MS with platform‐independent separation
Authors: Zürbig Petra , Renfrow Matthew B. , Schiffer Eric , Novak Jan , Walden Michael , Wittke Stefan , Just Ingo , Pelzing Matthias , Neusüß Christian , Theodorescu Dan , Root Karen E. , Ross Mark M. , Mischak Harald 
Published: April 2006

AbstractCE‐MS is a successful proteomic platform for the definition of biomarkers in different body fluids. Besides the biomarker defining experimental parameters, CE migration time and molecular weight, especially biomarker's sequence identity is an indispensable cornerstone for deeper insights into the pathophysiological pathways of diseases or for made‐to‐measure therapeutic drug design. Therefore, this report presents a detailed discussion of different peptide sequencing platforms consisting of high performance separation method either coupled on‐line or off‐line to different MS/MS devices, such as MALDI‐TOF‐TOF, ESI‐IT, ESI‐QTOF and Fourier transform ion cyclotron resonance, for sequencing indicative peptides. This comparison demonstrates the unique feature of CE‐MS technology to serve as a reliable basis for the assignment of peptide sequence data obtained using different separation MS/MS methods to the biomarker defining parameters, CE migration time and molecular weight. Discovery of potential biomarkers by CE‐MS enables sequence analysis via MS/MS with platform‐independent sample separation. This is due to the fact that the number of basic and neutral polar amino acids of biomarkers sequences distinctly correlates with their CE‐MS migration time/molecular weight coordinates. This uniqueness facilitates the independent entry of different sequencing platforms for peptide sequencing of CE‐MS‐defined biomarkers from highly complex mixtures.
Simultaneous enantioseparation and sensitive detection of eight β‐blockers using capillary electrochromatography‐electrospray ionization‐mass spectrometry
Authors: Zheng Jack , Shamsi Shahab A. 
Published: April 2006

AbstractThe feasibility of using vancomycin chiral stationary phase (CSP) and polar organic eluent is investigated for simultaneous enantioseparation of eight β‐blockers using CEC coupled to ESI mass spectrometric detection (ESI‐MS). The internally tapered capillaries were utilized to pack CEC‐MS columns. As compared to externally tapered columns, the use of internally tapered columns demonstrated enhanced stability, durability, and reproducibility. A mixture containing methanol/ACN/acetic acid/triethylamine at 70:30:1.6:0.2 v/v/v/v was considered as optimum mobile phase since it provided a good compromise between resolution and analysis time. As expected, sheath liquid and ESI‐MS parameters mainly influenced the detection sensitivity. Interestingly, structural information of β‐blockers was available by varying the MS fragmentor voltage using in‐house CID in the scan mode. In order to maximize the chiral/achiral resolution, various column‐coupling approaches using teicoplanin as complementary CSP to vancomycin were tested. Several changes in the elution order of β‐blockers were observed using multimodal CSPs with some improvement in chiral or achiral resolution. The quantitative aspects of the CEC‐MS method were demonstrated using R‐ and S‐talinolol as internal standards. The calibration curves of β‐blockers showed good linearity in the range of 3–600 µM. The enantiomer of β‐blockers at a concentration of 30 nM was detectable. Furthermore, both 0.1 and 1% of the S‐enantiomer could be precisely quantified in the presence of 99.9 and 99% of the R‐isomer of β‐blocker.
Progress in capillary electrophoresis coupled to matrix‐assisted laser desorption/ionization – time of flight mass spectrometry
Authors: Huck Christian W. , Bakry Rania , Huber Lukas A. , Bonn Günther K. 
Published: April 2006

AbstractIn this review the most important techniques developed to hyphenate CE to MALDI‐TOF‐MS are summarized. The principles of the different interfaces and ways to solve the hyphenation problem are explained and discussed in detail. The most important applications especially in the proteomic field are reviewed, and the advantages of CE‐MALDI‐TOF‐MS for the analysis of these compounds compared to other techniques such as ESI‐MS are exhaustingly discussed from a critical point of view. CE coupled to MALDI‐TOF‐MS has started to overpass traditionally used CE‐coupling techniques, especially CE‐ESI‐MS, offering the possibility to analyze samples of interest even weeks after CE analysis and using multiplexing systems for high‐sample throughput.