bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colorimetric Sensing by Using Allosteric‐DNAzyme‐Coupled Rolling Circle Amplification and a Peptide Nucleic Acid–Organic Dye Probe
Authors: Ali M. Monsur , Li Yingfu 
Published: April 2009

AbstractTarget detection by the naked eye: The action of an RNA‐cleaving allosteric DNAzyme in response to ligand binding was coupled to a rolling circle amplification process to generate long single‐stranded DNA molecules for colorimetric sensing (see scheme). Upon hybridization of the resulting DNA with a complementary PNA sequence in the presence of a duplex‐binding dye, the color of the dye changed from blue to purple.magnified image
Probing Solid Catalysts under Operating Conditions: Electrons or X‐rays?
Authors: Thomas John Meurig , Hernandez‐Garrido Juan‐Carlos 
Published: April 2009

AbstractSeeing is believing: In light of recent advances, the pros and cons of using electrons and X‐rays for in situ studies of catalysts are analyzed: by using X‐rays the structure of bound reactants at steady state are obtained from extended X‐ray adsorption fine structure spectroscopy (EXAFS) data (see graph), thereby affording mechanistic insights.magnified image
Monitoring the Formation of Coordination Complexes Using Electrospray Mass Spectrometry
Authors: Mathieson Jennifer S. , Cooper Geoffrey J. T. , Pickering Alexandra L. , Keller Marco , Long De‐Liang , Newton Graham N. , Cronin Leroy 
Published: April 2009

AbstractLinked‐in: The rigid Schiff‐base ligand cis,trans‐1,3,5‐tris(pyridine‐2‐carboxaldimino) cyclohexane (ttop) is synthesized, and its complexation to copper(II) salts at a range of stoichiometries is investigated crystallographically by using electrospray mass spectrometry. Further, in‐situ mass spectrometry measurements allow the stepwise construction of the complexes to be observed.magnified imagecis,trans‐1,3,5‐Triaminocyclohexane (trans‐tach) has been shown to be an excellent ligand in the synthesis of discrete complexes, molecular clusters, and infinite architectures. Herein, we report the Schiff‐base derivitization of trans‐tach to form cis,trans‐1,3,5‐tris (pyridine‐2‐carboxaldimino) cyclohexane (ttop), and the complexation of this ligand with copper(II) salts. The complexation reaction leads to the crystallization of transition‐metal complexes with nuclearities of 1, 2, and 4, and the formation of the complexes can be followed stepwise, in real time, using electrospray mass spectrometry.
Photodimerization Processes in Self‐Assembled Chiral Oligo(p‐phenylenevinylene) Bolaamphiphiles
Authors: George Subi J. , de Greef Tom F. A. , Bovee Ralf , van Dongen Joost L. J. , Schenning Albertus P. H. J. , Meijer E. W. 
Published: April 2009

AbstractHighly discriminating cycloaddition: An unexpected [2+2] cycloaddition in self‐assembled cation OPV‐monolayered vesicles is described. Remarkably, the photochemical reaction is chemo‐, regio‐, and stereoselective, which is most likely the result of the well‐controlled supramolecular organization of the OPV units in the monolayer.magnified imageAn oligo(p‐phenylene vinylene) (OPV) amphiphile has been synthesized with a positively charged head group on one end and a hydrophilic ethyleneglycol wedge on the other. In water, this bolaamphiphile forms vesicles consisting of a monolayer in which the OPV surfactants are organized in a helical head‐to‐tail fashion. Mass spectrometry analysis and reversed‐phase high performance liquid chromatography (RP‐HPLC) reveals that because of the presence of two double bonds in the OPV units, photo‐induced [2+2] cycloaddition takes place resulting in polymerization of the surfactants. Performing RP‐HPLC allowed the OPV dimer to be isolated in a sufficient amount to perform a variety of one‐ and two‐dimensional NMR experiments. These experiments show a highly stereoselective photochemical cycloaddition process resulting in a regioselective head‐to‐tail dimerization with a stereoselective syn arrangement.
The DING family of proteins: ubiquitous in eukaryotes, but where are the genes?
Authors: Berna Anne , Scott Ken , Chabrière Eric , Bernier François 
Published: April 2009

AbstractPstS and DING proteins are members of a superfamily of secreted, high‐affinity phosphate‐binding proteins. Whereas microbial PstS have a well‐defined role in phosphate ABC transporters, the physiological function of DING proteins, named after their DINGGG N termini, still needs to be determined. PstS and DING proteins co‐exist in some Pseudomonas strains, to which they confer a highly adhesive and virulent phenotype. More than 30 DING proteins have now been purified, mostly from eukaryotes. They are often associated with infections or with dysregulation of cell proliferation. Consequently, eukaryotic DING proteins could also be involved in cell–cell communication or adherence. The ubiquitous presence in eukaryotes of proteins structurally and functionally related to bacterial virulence factors is intriguing, as is the absence of eukaryotic genes encoding DING proteins in databases. DING proteins in eukaryotes could originate from unidentified commensal or symbiotic bacteria and could contribute to essential functions. Alternatively, DING proteins could be encoded by eukaryotic genes sharing special features that prevent their cloning. Both hypotheses are discussed.
Efficient transfection of mouse‐derived C2C12 myoblasts using a matrigel basement membrane matrix
Authors: Balcı Burcu , Dinçer Pervin 
Published: April 2009

AbstractMyogenic cell lines have been used widely in the study of myogenic differentiation, muscle regeneration and homeostasis, but, myoblasts and myotubes are difficult to transfect using conventional techniques. We have used liposome‐based transfection method to introduce a green fluorescence protein (GFP)‐expressing plasmid into Matrigel basement membrane matrix‐coated C2C12 mouse myoblast cells. Myoblasts adhered and proliferated more rapidly on a Matrigel; thus, a dramatic increase in transfection efficiency can be obtained compared to Matrigel‐untreated cells. Transfection efficiency was determined by counting fluorescent and total cells from six random fields for each condition. This protocol results in efficient (up to 60–70%) transfection of C2C12 myoblasts, high levels of GFP expression and low rate of cell death (10%). This technique is rapid, reliable, uses a lipid‐based transfection reagent, and yields high transfection rates in a previously hard‐to‐transfect cell type.
Metabolic and evolutionary engineering research in Turkey and beyond
Authors: Çakar Zeynep Petek 
Published: April 2009

AbstractThis review discusses metabolic engineering research with an emphasis on evolutionary (whole cell and protein) engineering, which is an inverse metabolic engineering approach. For each section on metabolic, inverse metabolic and evolutionary engineering research, a general review of the major global studies in the literature is made and research examples from Turkey are given and discussed. It is expected that with the rapid development in systems biology and the novel powerful analytical technologies to identify the genetic basis of cellular phenotypes, metabolic and evolutionary engineering research will become widespread and increasingly important in Turkey, following global scientific trends.
Kinetic optimization of a protein‐responsive aptamer beacon
Authors: Hall Bradley , Cater Sean , Levy Matt , Ellington Andrew D. 
Published: April 2009

AbstractAptamers have been utilized as biosensors because they can be readily adapted to sensor platforms and signal transduction schemes through both rational design and selection. One highly generalizable scheme for the generation of the so‐called aptamer beacons involves denaturing the aptamer with antisense oligonucleotides. For example, rational design methods have been utilized to adapt anti‐thrombin aptamers to function as biosensors by hybridizing an antisense oligonucleotide containing a quencher to the aptamer containing a fluorescent label. In the presence of thrombin, the binding equilibrium is shifted, the antisense oligonucleotide dissociates, and the beacon lights up. By changing the affinity of the antisense oligonucleotide for the aptamer beacon, it has proven possible to change the extent of activation of the beacon. More importantly, modulating interactions between the antisense oligonucleotide and the aptamer strongly influences the kinetics of activation. Comparisons across multiple, designed aptamer beacons indicate that there is a strong inverse correlation between the thermodynamics of hybridization and the speed of activation, a finding that should prove to be generally useful in the design of future biosensors. By pre‐organizing the thrombin‐binding quadruplex within the aptamer the speed of response can be greatly increased. By integrating these various interactions, we were ultimately able to design aptamer beacons that were activated by threefold within 1 min of the addition of thrombin. Biotechnol. Bioeng. 2009;103: 1049–1059. © 2009 Wiley Periodicals, Inc.
Integrated fragmentation of human IgG and purification of Fab using a reactant adsorptive membrane bioreactor separator system
Authors: Yu Deqiang , Ghosh Raja 
Published: April 2009

AbstractThis article discusses an integrated separation–reaction–separation scheme for producing Fab fragment directly from human immunoglobulin G (hIgG) present in serum feed. The novel reactant adsorptive membrane bioreactor separator (or RAMBS) system used in the current study consisted of a stack of microporous adsorptive membranes held within a temperature controlled module. The membrane stack, in the presence of salt, selectively and reversibly adsorbed hIgG by hydrophobic interaction while allowing most other serum proteins to flow through. The bound hIgG was then fragmented by pumping a solution of papain through the reactor at controlled temperature and flow rate. The salt concentration and pH for reaction and separation were systematically optimized using pure hIgG as reactant. The Fab fragment was separated from undigested hIgG and other byproducts such as Fc fragment based on their differences in hydrophobicity. Under optimal conditions, Fab was obtained in the reaction flow through while the other proteins remained bound to the membrane, these being subsequently eluted by lowering the salt concentration. The RAMBS system in addition to being convenient from process integration and intensification points of view also showed higher catalytic efficiency of papain in comparison to that in liquid phase reactions. Biotechnol. Bioeng. 2009; 104: 152–161 © 2009 Wiley Periodicals, Inc.
Wege zur Endomykorrhiza. Einladung ans Buffet
Authors: Schaarschmidt Sara , Hause Bettina , Strack Dieter 
Published: April 2009

AbstractDie Lebensgemeinschaft mit Mykorrhizapilzen stellt Pflanzen mineralische Nährstoffe und Wasser zur Verfügung und gilt daher als evolutionäre Grundlage für die Entwicklung der Landpflanzen. Die heute weit verbreitete arbuskuläre Mykorrhiza (AM) ist insbesondere unter widrigen Bedingungen (Nährstoffmangel, Trocken‐, Salz‐ oder Schwermetallstress sowie Pathogenbefall) für die Pflanze von Nutzen. Der pilzliche AM‐Partner, der obligat auf die Interaktion angewiesen ist, wird im Gegenzug mit Kohlenhydraten versorgt. Der Artikel beschreibt den aktuellen Stand der Forschung bezüglich der Etablierung und Regulation der AM durch die Pflanze. Es werden die frühen Erkennungssignale und die nachfolgende Wegbereitung der Pflanze für den eindringenden Pilz, die Kohlenhydratversorgung des AM‐Pilzes, wie auch die Limitierung der pilzlichen Infektionen mittels Autoregulation und die Rolle der Phytohormone für eine funktionelle und ausgeglichene Symbiose behandelt.
Weshalb hemmen Würmer Allergien? Parasiten als Immunologen
Authors: Lucius Richard , Hartmann Susanne 
Published: April 2009

AbstractParasitische Würmer können in ihren Wirten nur überleben, indem sie deren Immunsystem gezielt beeinflussen und Entzündungsreaktionen herabregulieren, die gegen sie gerichtet sind. Diese Immunmodulation wirkt sich auch auf Entzündungen anderer Genese aus. Deshalb leiden Menschen, die mit bestimmten Würmern infiziert sind, seltener unter Allergien als wurmfreie Personen. In Mausmodellen können viele entzündungsbedingte Erkrankungen durch Wurminfektionen geheilt werden. Diese Wirkung geht unter anderem auf Proteine zurück, die von den Parasiten sezerniert werden. Solche Moleküle könnten eine Basis für die Entwicklung neuer Therapien gegen allergische und entzündliche Erkrankungen sein.
Alzheimer – Mechanismen und therapeutische Ansätze. Warum wir im Alter dement werden
Authors: Haass Christian 
Published: April 2009

AbstractAlzheimer ist eine altersabhängige neurodegenerative Demenzerkrankung, die pathologisch vor allem durch Amyloid‐Plaques und neurofibrilläre Bündel gekennzeichnet ist. Für den massiven neuronalen Zellverlust wird das Amyloid β‐Peptid verantwortlich gemacht, das selbst aus einem Vorläuferprotein, dem β‐Amyloid Precursor Protein entsteht. Sekretasen schneiden das Amyloid β‐Peptid aus dem Vorläufer in einem physiologisch normalen Prozess heraus. Sekretasen sind Zielmoleküle therapeutischer Intervention, da deren Inhibition die Aβ‐Produktion reduziert und die Gedächtnisleistung zumindest im Tierversuch stabilisiert. Darüber hinaus führt eine Impfung gegen das Amyloid β‐Peptid zu einer Reduktion der Amyloidplaquedichte. Die Vor‐ und Nachteile moderner Therapieansätze werden vor dem Hintergrund erster klinischer Versuchsergebnisse an Alzheimerpatienten diskutiert.
Wie wachsen Tropenbäume? Jahrringe als Ausdruck von Klimabedingungen und Lebensform
Authors: Bräuning Achim , Volland‐Voigt Franziska , von Schnakenburg Peter 
Published: April 2009

AbstractDas Wachstum tropischer Baumarten hängt von der Saisonalität des lokalen Klimas ab. In Gebieten mit markanter Trockenzeit stellen viele Baumarten die kambiale Aktivität zeitweise ein und bilden Jahrringe. In feuchten Bergregenwäldern wird das Baumwachstum nach kurzen trockeneren Phasen eingestellt. Mit einer Kombination von Zuwachsmessungen und holzanatomischen Analysen kann die Klimasteuerung der Holzbildung entschlüsselt werden. Die intra‐annuelle Variabilität der Holzdichte und der Verhältnisse stabiler Isotope erlauben die klimaökologische Interpretation der Signale im Holz.
Stammzellen in Hydra. Evolutionäres Vermächtnis
Authors: Bosch Thomas C. G. 
Published: April 2009

AbstractDie bemerkenswerte Regenerationsfähigkeit und potenzielle Unsterblichkeit von Hydra beruht auf einem Lebenszyklus, in dem Vermehrung ausschließlich ungeschlechtlich durch Knospung erfolgt. Dies setzt voraus, dass jeder Polyp mit einer großen Zahl von Stammzellen ausgestattet ist, die kontinuierlich zu Selbsterneuerung und Differenzierung befähigt sind. Neue Technologien erlauben es nun erstmalig, diese Zellen in vivo zu studieren und die beteiligten Gene zu charakterisieren. Hydra verspricht neben dem Verständnis von wichtigen Aspekten der Stammzellbiologie auch Einblick in den evolutionären Ursprung dieser Zellen.
Der Räuber unter den Mistkäfern
Authors: Wendler Silke 
Published: April 2009

AbstractMistkäfer sind weltweit verbreitete, friedliche Insekten und bekannt dafür, dass sie eine ruhige “Dung”‐Kugel schieben, um sich später von den darin enthaltenen Bakterien und der sich zersetzenden Biomasse zu ernähren. Trond Larsen und seine Arbeitsgruppe haben jedoch im peruanischen Regenwald einen Räuber unter den Mistkäfern gefunden. Die Art Deltochilum valgum ernährt sich ausschließlich von Tausendfüßern.
Identification, characterization and quantification of specific neuropeptides in rat spinal cord by liquid chromatography electrospray quadrupole ion trap mass spectrometry
Authors: Beaudry Francis , Ferland Catherine E , Vachon Pascal 
Published: April 2009

AbstractSubstance P and CGRP play a central role in neuropathic pain development and maintenance. Additionally, dynorphin A is an endogenous ligand of opioid receptors implicated in the modulation of neurotransmitters including neuropeptides, such as substance P and CGRP. This manuscript proposes a method to characterize, identify and quantify substance P, CGRP and dynorphin A in rat spinal cord by HPLC‐ESI/MS/MS. Rat spinal cords were collected and homogenized into a TFA solution. Samples were chromatographed using a microbore C8 100 × 1 mm column and a 19 min linear gradient (0:100 → 40:60; ACN:0.2% formic acid in water) at a flow rate of 75 µL/min for a total run time of 32 min. The peptides were identified in rat spinal cord based on full‐scan MS/MS spectra. Substance P, CGRP and dynorphin A were predominantly identified by the presence of specific b CID fragments. Extracted ion chromatogram (XIC) suggested selected mass transitions of 674 → [600 + 254], 952 → [1215 + 963] and 717 → [944 + 630] for substance P, CGRP and dynorphin A can be used for isolation and quantitative analysis. A linear regression (weighted 1/x) was used and coefficients of correlations (r) ranging from 0.990 to 0.999 were observed. The precision (%CV) and accuracy (%NOM) observed were 10.9–14.4% and 8.9–14.2%, 8.8–13.0% and 91.0–110.2% and 97.2–107.3% and 91.8–97.3% for substance P, CGRP and dynorphin A respectively. Following the analysis of rat spinal cords, the mean endogenous concentrations were 110.7, 2541 and 779.4 pmol/g for substance P, CGRP and dynorphin A respectively. The results obtained show that the method provides adequate figures of merit to support targeted peptidomic studies aimed to determine neuropeptide regulation in animal neuropathic and chronic pain models. Copyright © 2009 John Wiley & Sons, Ltd.
Computer facilitated generalized coordinate transformations of partial differential equations with engineering applications
Authors: Elkamel A. , Bellamine F.H. , Subramanian V.R. 
Published: April 2009

AbstractPartial differential equations (PDEs) play an important role in describing many physical, industrial, and biological processes. Their solutions could be considerably facilitated by using appropriate coordinate transformations. There are many coordinate systems besides the well‐known Cartesian, polar, and spherical coordinates. In this article, we illustrate how to make such transformations using Maple. Such a use has the advantage of easing the manipulation and derivation of analytical expressions. We illustrate this by considering a number of engineering problems governed by PDEs in different coordinate systems such as the bipolar, elliptic cylindrical, and prolate spheroidal. In our opinion, the use of Maple or similar computer algebraic systems (e.g. Mathematica, Reduce, etc.) will help researchers and students use uncommon transformations more frequently at the very least for situations where the transformations provide smarter and easier solutions. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 365–376, 2011
Synthesis and Structure–Activity Correlation of a Brunsvicamide‐Inspired Cyclopeptide Collection
Authors: Walther Thilo , Renner Steffen , Waldmann Herbert , Arndt Hans‐Dieter 
Published: April 2009

AbstractCyanobacterial cyclopeptides: A series of analogues of the cyanobacterial cyclopeptide brunsvicamide A was prepared by effective solid‐support‐based total synthesis. Variations in stereochemistry revealed the importance of the D‐lysine and the L‐isoleucine residues for the substrate‐competitive inhibitory activity of brunsvicamide A against carboxypeptidase A.magnified imageThe brunsvicamides are modified cyclopeptides from cyanobacteria, cyclised through the ε‐amino group of a D‐lysine unit. They are functionalised with urea groups and show potent carboxypeptidase inhibitory activities. In order to unravel the structural parameters that determine their activities, a collection of brunsvicamide analogues with varied amino acid structures and stereochemistries was synthesised by a combined solution‐ and solid‐phase approach. Biochemical investigation of the compound collection for carboxypeptidase A inhibition revealed that the presence of D‐lysine and L‐isoleucine in the urea section is important for inhibition. It was found that brunsvicamide A is a substrate‐competitive inhibitor of carboxypeptidase A. These findings are in agreement with the substrate specificity of the enzyme and were rationalised by computational studies, which showed the high relevance of the lysine stereochemistry for inhibitory activity.
Syntheses, Structures, and Comprehensive NMR Spectroscopic Investigations of Hetero‐Chalcogenidometallates: The Right Mix toward Multinary Complexes
Authors: Ruzin Eugen , Zent Eldar , Matern Eberhard , Massa Werner , Dehnen Stefanie 
Published: April 2009

AbstractLibrary of semiconductors: Mixtures of binary chalcogenidostannate anions in protic solution show statistic chalcogenide exchange (see scheme), which is examined by comprehensive NMR investigations, DFT calculations and chemical reactions. A simple approach is provided to generate a library of semiconductor compounds with finely tuned opto‐electronic properties.magnified imageAqueous solutions of ternary ortho‐chalcogenidostannate anions [SnE14−xE2x]4− (E1, E2=S, Se, Te) have been generated following different routes that all lead to equilibria of all possible permutations of binary and ternary anions. This has been rationalized by means of NMR studies that can be explained by calculations using density functional theory (DFT) methods. Thus, if one reacts such solutions with transition‐metal ions, quaternary M/Sn/E1/E2 anions are obtained, which exhibit coordination by different ternary chalcogenidostannate ligands. The electronic excitation energies of the corresponding alkali metal salts lie between the Eg values of compounds containing either M/Sn/E1 or M/Sn/E2 anions. In this way, we provide a simple approach toward a library of semiconductor compounds with finely‐tuned optoelectronic properties.