bluuebunny/crossref_metadata_2025_split huggingface dataset:
The clinical anatomy of congenital portosystemic venous shunts
Authors: Stringer Mark D. 
Published: December 2007

AbstractCongenital portosystemic venous shunts are rare. Their gross anatomy has not been well defined. Four different varieties of congenital portosystemic venous shunts are described in six children seen during a 10‐year period, focusing on the anatomy of the shunt as determined by imaging studies and surgery. A detailed review of the literature indicates that congenital portosystemic venous shunts are best classified as: extrahepatic or intrahepatic. Extrahepatic shunts may be further subdivided into portocaval shunts (type 1 end‐to‐side and type 2 side‐to‐side) and others. Intrahepatic shunts are due to an abnormal intrahepatic connection between the portal vein and hepatic vein/inferior vena cava or a persistent patent ductus venosus. Additional congenital anomalies, particularly cardiac malformations, may be associated with any type. Some congenital intrahepatic portosystemic venous shunts close spontaneously in infancy; all other congenital portosystemic venous shunts tend to remain patent. To a variable extent, depending largely on the volume and duration of the shunt, affected individuals are at risk of developing hepatic encephalopathy and/or an intrahepatic tumor. The key to understanding the pathogenesis of these shunts lies in the normal developmental mechanisms underlying the formation of the portal vein and inferior vena cava in the embryo. Clin. Anat. 21:147–157, 2008. © 2008 Wiley‐Liss, Inc.
Parallel Analysis of Two Analytes in Solutions or on Surfaces by Using a Bifunctional Aptamer: Applications for Biosensing and Logic Gate Operations
Authors: Elbaz Johann , Shlyahovsky Bella , Li Di , Willner Itamar 
Published: December 2007

AbstractA bifunctional aptamer that includes two aptamer units for cocaine and adenosine 5′‐monophosphate (AMP) is blocked by a nucleic acid to form a hybrid structure with two duplex regions. The blocked bifunctional aptamer assembly is used as a functional structure for the simultaneous sensing of cocaine or AMP. The blocked bifunctional aptamer is dissociated by either of the two analytes, and the readout of the separation of the sensing structure is accomplished by a colorimetric detection, by a released DNAzyme, or by electronic means that use Faradaic impedance spectroscopy or field‐effect transistors. In one configuration, the blocked bifunctional aptamer structure is separated by the substrates cocaine or AMP, and the displaced blocker units act as a horseradish peroxidase‐mimicking DNAzyme that permits the colorimetric detection of the analytes. In the second system, the blocked bifunctional aptamer hybrid is associated with a Au electrode. The displacement of the aptamer by any of the substrates alters the interfacial electron transfer resistance at the electrode surface, thus providing an electronic signal for the sensing process. In the third configuration, the blocked aptamer hybrid is linked to the gate of a field‐effect transistor device. The separation of the complex by means of any of the analytes, cocaine, or AMP alters the gate potential, and this allows the electronic transduction of the sensing process by following the changes in the gate‐to‐source potentials. The different systems enable not only the simultaneous detection of the two analytes, but they provide a functional assembly that performs a logic gate “OR” operation.
The Role of the Conserved Threonine in P450BM3 Oxygen Activation: Substrate‐Determined Hydroxylation Activity of the Thr268Ala Mutant
Authors: Cryle Max J. , De Voss James J. 
Published: December 2007

AbstractThe hydroxylation activity of the Thr268Ala mutant of P450BM3 has been shown to occur to varying degrees with small alterations in the structure of a fatty‐acid substrate. Ten substrates were investigated, including straight chain, branched chain and cis‐cyclopropyl substituted fatty acids with a straight‐chain length that varied between 12 and 16 carbon atoms. The efficacy of the hydroxylation activity appeared to be governed by the chain length of the substrate. Substrates possessing 14 to 15 carbons afforded the highest levels of activity, which were comparable with the wild‐type enzyme. Outside of this window, straight‐chain fatty acids showed reduced activity over the other substrate types. These results provide a cautionary tale concerning the loss of ferryl activity in such cytochrome P450 threonine to alanine mutants, as the nature of the substrate can determine the extent to which hydroxylation chemistry is abolished.
H2O2/Nitrite‐Induced Post‐translational Modifications of Human Hemoglobin Determined by Mass Spectrometry: Redox Regulation of Tyrosine Nitration and 3‐Nitrotyrosine Reduction by Antioxidants
Authors: Chen Hauh‐Jyun Candy , Chang Chia‐Ming , Lin Wen‐Peng , Cheng Dar‐Long , Leong Mei‐I 
Published: December 2007

AbstractCovalent modifications of proteins by endogenous reactive nitrogen oxide species lead to cytotoxic effects that are implicated in diseases associated with chronic infections and inflammation. Tyrosine nitration is a major post‐translational modification of proteins by reactive nitrogen oxide species. Recent studies suggest that nitrotyrosine is not a permanent protein modification. We previously demonstrated that lipoyl dehydrogenase is capable of converting 3‐nitrotyrosine into 3‐aminotyrosine in the presence of certain reducing agents. In this study, we compared the abilities of various hemoproteins, hemin, and the cobalt‐containing cofactor cyanocobalamin to mediate H2O2/nitrite‐dependent tyrosine nitration and found that these hemoproteins and metal‐containing cofactors also catalyzed the reduction of 3‐nitrotyrosine to various extents in the presence of thiol reducing agents or ascorbate. The H2O2/nitrite‐induced post‐translational modifications of human hemoglobin identified by nanoLC/nanospray ionization tandem mass spectrometric analysis of the tryptic digest include nitration of tyrosine and tryptophan, as well as oxidation of methionine and cysteine residues. Nitration of human hemoglobin by H2O2/nitrite was detected on Tyr24 and Tyr42 (α‐chain) and on Tyr130 and Trp15 (β‐chain) in the αβ‐dimer. Oxidation of methionine and cysteine residues was also observed. Furthermore, hemoglobin also catalyzed nitro reduction of 3‐nitrotyrosine to form 3‐aminotyrosine, at Tyr24 in the α‐chain peptide of human Hb in the presence of ascorbate. The enhanced peroxidase activity of nitrated hemoglobin can be reversed by the antioxidant ascorbate. These results suggest a possible in vivo pathway for hemoglobin contributing to denitration of nitrated proteins through redox regulation.
Supramolecular Gels Formed by Amphiphilic Low‐Molecular‐Weight Gelators of Nα,Nε‐Diacyl‐L‐Lysine Derivatives
Authors: Suzuki M. , Yumoto M. , Shirai H. , Hanabusa K. 
Published: December 2007

AbstractSimple L‐lysine derivatives, Nα‐hexanoyl‐Nε‐lauroyl‐L‐lysine (1), its alkali metal salts (2–4), and two‐component compounds that consist of 1 with 2 to 4, were synthesized and their hydrogelation and organogelation properties were studied. Addition of hydrochloric acid to an aqueous solution of the alkali metal salt at room temperature produced a translucent hydrogel. This hydrogelation occurred as a result of a change in nanostructure from micelle‐like aggregates to nanofibers, which was induced by partial protonation of the carboxylate to form a carboxylic acid. On the other hand, two‐component low‐molecular‐weight gelators exhibited amphiphilic gelation behavior and functioned as not only hydrogelators, but also as organogelators. FTIR studies revealed that lateral ionic interactions between the carboxylate, alkali metal cation, carboxylic acid, and protons, in addition to hydrogen‐bonding and van der Waals interactions play a very important role in hydrogelation. Furthermore, it was found that the water‐insoluble carboxylic acid compound underwent a precipitation–dissolution transition with a thermally reversible sol–gel transition in the two‐component gelator systems.
A Pattern Recognition Based Fluorescence Quenching Assay for the Detection and Identification of Nitrated Explosive Analytes
Authors: Hughes Andrew D. , Glenn Ian C. , Patrick Andrew D. , Ellington Andrew , Anslyn Eric V. 
Published: December 2007

AbstractHerein we report a differential array of micelle‐solubilized fluorophores for the detection and identification of small nitrated analytes, such as the explosives TNT, tetryl, RDX and HMX. The quenching ability of the analytes can be used to correlate their analyte identity, wherein the quenching patterns generated from the differential array are used in linear discriminant analysis (LDA). LDA results in a well‐clustered two‐dimensional plot, and a jack‐knife analysis of the data suggests that this system can be used to identify unknown samples of analyte with 96 % accuracy and with a detection limit of 19 μM.
The Calculation of Polar Surface Area from First Principles: An Application of Quantum Chemical Topology to Drug Design
Authors: Bytheway Ian , Darley Michael G. , Popelier Paul L. A. 
Published: December 2007

AbstractThe calculation of polar surface areas (PSA) from the electron density using quantum chemical topology (QCT) and a newly developed algorithm to determine isodensity surface areas is described. PSA values were calculated from the atomic partitioning of B3LYP/6‐311G* wavefunctions and the results described herein represent the first application of this new algorithm. PSA values were calculated for forty drugs and compared to the topological polar surface area (TPSA) and those calculated by the QikProp program. Oral bioavailabilities predicted from the QCT PSA values for a subset of twenty drugs (the Palm set) were similar to those predicted by the dynamic polar surface area (DPSA) and in general, are in agreement with the observed values. Overall, PSA values obtained from QCT were generally similar to the DPSA, TPSA, and QikProp values, though differences in fragment contributions were found, with nitrogen‐bearing functional groups showing the largest variation between methods. Differences between methods showed how the calculation of the PSA is dependent on the method used and, therefore, judicious application of the upper limits used in the prediction of oral bioavailability is warranted. These results also indicate that, because of the differences in the way PSA values are calculated, values from the different methods should not be used interchangeably.
Carbonic Anhydrase Inhibitors: Binding of Indanesulfonamides to the Human Isoform II
Authors: D'Ambrosio Katia , Masereel Bernard , Thiry Anne , Scozzafava Andrea , Supuran Claudiu T. , De Simone Giuseppina 
Published: December 2007

AbstractIndanesulfonamides are interesting lead compounds for designing selective inhibitors of the different isoforms of the zinc enzyme Carbonic Anhydrase (CA). Herein, we report for the first time the X‐ray crystal structure of two such derivatives, namely indane‐5‐sulfonamide and indane‐2‐valproylamido‐5‐sulfonamide, in complex with the physiologically dominant human isoform II. The structural analysis reveals that, although these two inhibitors have quite similar chemical structures, the arrangement of their indane ring within the enzyme active site is significantly diverse. Thus, our findings suggest that the introduction of bulky substituents on the indane‐sulfonamide ring may alter the binding mode of this potent class of CA inhibitors, although retaining good inhibitory properties. Accordingly, the introduction of bulky tail moieties on the indane‐sulfonamide scaffold may represent a powerful strategy to induce a desired physicochemical property to an aromatic sulfonamide or to obtain inhibitors with diverse inhibition profiles and selectivity for various mammalian CAs.
Die Anwendung von numerischen Methoden zur Tragwerksanalyse von Baudenkmälern
Authors: Lourenço Paulo 
Published: December 2007

AbstractDie Erhaltung und Sanierung von historischen Bauwerken stellen immer noch eine Herausforderung für die Praktiker dar, da gerade in den letzten Jahrzehnten beträchtliche Fortschritte und Erkenntnisse in der Forschung erzielt werden konnten, insbesondere in Bezug auf zerstörungsfreie Prüfverfahren, Erfassung der mechanischen Eigenschaften, Berechnungsmethoden zur realitätsnahen numerischen Untersuchung, sowie zu traditionellen als auch innovativen Baumaterialien und Techniken. In diesem Beitrag werden die Bedeutung der statisch‐konstruktiven Denkmalpflege und ihrer ingenieurtechnischen Aspekte erörtert und die Anwendung von modernen numerischen Berechnungsmethoden anhand von ausgewählten Fallstudien diskutiert. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nichtlineare Nachstellung von Mauerwerksversuchen am Beispiel von Zug‐ und Biege‐zugbeanspruchung
Authors: Jäger Wolfram , Hoffmann Jens , Schöps Peter 
Published: December 2007

AbstractDie beiden aktuellen deutschen Bemessungsnormen für Mauerwerk enthalten für den Nachweis von Zugbeanspruchungen (Biegezug und zentrischer Zug jeweils parallel zu den Lagerfugen) sehr einfache und praktische Beziehungen, die innerhalb der Zugbruchkriterien den Einfluss der Lagerfugen vernachlässigen. In Versuchen wurde jedoch immer wieder ein derartiger Einfluss festgestellt. Mit Hilfe nichtlinearer numerischer Methoden lässt sich das Tragverhalten von Mauerwerk immer besser nachstellen und so können in Parameterstudien die Einflüsse einzelner Mauerwerkskomponenten ohne den störenden Einfluss unvermeidbarer Streuungen im Experiment qualitativ als auch – in eingeschränktem Maße – quantitativ bewertet werden. Der vorliegende Beitrag berichtet über zwei Untersuchungsreihen, in denen sich der Einfluss der Mörtelfestigkeit und der Lagerfugendicke auf die Biegezugfestigkeit und die zentrische Zugfestigkeit parallel zu den Lagerfugen offensichtlich herausstellen. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sensitivitätsanalyse und Parameteridentifikation von bestehenden Mauerwerkstrukturen
Authors: Schlegel Roger , Will Johannes 
Published: December 2007

AbstractDer Beitrag stellt neue Softwareentwicklungen und Simulationsverfahren vor, mit denen es möglich ist, komplexe Simulationsmodelle hinsichtlich ihrer Prognosefähigkeit, Robustheit und Abhängigkeit von streuenden Inputparametern zu überprüfen. Am Beispiel der Untersuchung bestehender Mauerwerkstrukturen wird gezeigt, wie mit Hilfe von Sensitivitätsstudien die Einflüsse einzelner Inputparameter bzw. Inputparametergruppen auf die Ergebnisgrößen eines numerischen Simulationsmodells ermittelt werden können. Auf der Basis von Sensitivitätsanalysen können anschließend mit Hilfe von Parameteridentifikationen gezielt fehlende Werte oder Wertebereiche von Inputparametern durch den inversen Abgleich von berechneten Ergebnissen mit gemessenen Werten ermittelt werden. Damit ist es möglich, sowohl fehlende bzw. auf experimentellem Wege nicht oder nur sehr aufwendig bestimmbare Materialkenngrößen zu erhalten als auch die erforderliche Prognosefähigkeit eines Simulationsmodells sicherzustellen. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mauerwerkswände unter zyklischer Schubbeanspruchung
Authors: Butenweg Christoph , Gellert Christoph , Meskouris Konstantin 
Published: December 2007

AbstractDie Tragfähigkeit von unbewehrten Mauerwerkswänden unter Erdbebenbeanspruchung wird in den Bemessungsnormen durch analytische Berechnungsformeln als Minimum der möglichen Versagensformen von Mauerwerksschubwänden abgeschätzt. Der seismische Standsicherheitsnachweis erfolgt kraftbasiert durch die Gegenüberstellung der Wandkapazität mit der nach dem Antwortspektrenverfahren ermittelten maximalen Beanspruchung. Der kraftbasierte Ansatz führt jedoch oft dazu, dass traditionelle Mauerwerksbauten schon bei moderaten Erdbebeneinwirkungen nicht mehr nachgewiesen werden können. Hier helfen verformungsbasierte Verfahren weiter, mit denen die Tragwerksreserven wesentlich besser ausgenutzt werden können. Grundlage zur Anwendung solcher Verfahren ist die Kenntnis der zyklischen Last‐Verformungskurven für die am horizontalen Lastabtrag beteiligten Schubwände. Der Verlauf der Kurven ist abhängig von der Wandgeometrie, der vertikalen Auflast, der Stein/Mörtel‐Kombination und dem Einspanngrad am Wandkopf. Aufgrund der Vielzahl möglicher Kombinationen stellen experimentelle Untersuchungen immer nur Tastuntersuchungen dar, so dass für eine parametrisierte Beschreibung der Kurven ergänzend numerische Simulationen und analytische Ansätze hinzugezogen werden müssen.In dem Beitrag wird die Problematik der Definition von zyklischen Last‐Verformungskurven diskutiert. Zunächst werden die verschiedenen Möglichkeiten zur Approximation der zyklischen Last‐Verformungskurven vorgestellt und hinsichtlich ihrer Qualität und praktischen Anwendbarkeit bewertet. Im Anschluss wird daraus ein Konzept für die Definition der Last‐Verformungskurven abgeleitet. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Festlegung von Ertüchtigungsmaßnahmen für erdbebengefährdete Bauwerke auf der Grundlage von Kollapsanalysen
Authors: Jäger Wolfram , Bakeer Tammam 
Published: December 2007

AbstractNachdem das Erdbeben von Dezember 2003 der Zitadelle von Bam, dem größten Lehmbaukomplex der Welt, schwerste Schäden zufügte, wurden viele Maßnahmen zur Beräumung und zum Wiederaufbau der Anlage eingeleitet. Der hohe Zerstörungsgrad wirft die Frage nach der Ertüchtigung der Bauwerke beim Wiederaufbau auf. Um die Versagensursachen der Gebäude abklären zu können, wurde für zwei Räume eines Hauses eine Einsturzsimulation durchgeführt. Dabei kam die Diskrete Elementmethode (DEM) gekoppelt mit der Finiten‐Element‐Methode (FEM) zum Einsatz. Für die Erdbebenanalyse wurde die Standard‐Software LS‐DYNA angewendet. Das Mauerwerk innerhalb der Diskreten Elemente ist mittels Makromodellierung verschmiert abgebildet worden. Die Elementierung wurde mit Hilfe einer CAD‐Software erstellt, und zwar so, dass Versagensflächen Grenzflächen der Diskreten Elemente darstellen. Es wurde die Einsturzsimulation des Tragwerks zuerst im Originalzustand ohne Bewehrung durchgeführt, um die Schwachstellen und die Bruchsequenz zu ermitteln. Danach erfolgte die schrittweise Ertüchtigung durch Bewehrung aus Glasfaserstäben, die systematisch an verschiedenen Stellen angeordnet wurden, jeweils verbunden mit einer erneuten Analyse des Gesamtverhaltens. Auf diese Weise konnte die minimal notwendige Bewehrung bestimmt werden, um den Einsturz bei einem erneuten Erdbeben gleicher Art und Stärke zu verhindern. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
α‐Phenyl‐n‐tert‐butyl‐nitrone reduces lipopolysaccharide‐induced white matter injury in the neonatal rat brain
Authors: Fan Lir‐Wan , Mitchell Helen J. , Tien Lu‐Tai , Zheng Baoying , Pang Yi , Rhodes Philip G. , Cai Zhengwei 
Published: December 2007

AbstractLipopolysaccharide (LPS)‐induced white matter injury in the neonatal rat brain is at least partially associated with oxidative stress. α‐Phenyl‐n‐tert‐butyl‐nitrone (PBN) (100 mg/kg) significantly attenuated LPS (1 mg/kg)‐induced brain injury, as indicated by the reduction in bilateral ventricular enlargement, apoptotic cell death of oligodendrocytes (OLs), and the loss of OL immunoreactivity in the neonatal rat brain. Protection of PBN was linked with the attenuated oxidative stress induced by LPS, as indicated by the decreased elevation of 8‐isoprostane content and by the reduced number of 4‐hydroxynonenal or malondialdehyde positive OLs following LPS exposure. Interestingly, while LPS exposure elevated, rather than depleted, levels of the reduced glutathione (GSH) and the GSH/GSSG (oxidized form) ratio, LPS exposure significantly suppressed glutathione peroxidase activity in the rat brain. PBN attenuated LPS‐induced alterations in glutathione homeostasis in the rat brain. Additionally, the inflammatory responses were also reduced in the PBN‐treated brain, as indicated by the decreased number of activated microglia following LPS exposure and by the consequently decreased elevation of interleukin1‐β and tumor necrosis factor‐α contents in the rat brain. The overall results suggest that antioxidant PBN, more than a straightforward free radical scavenger, may also involve anti‐inflammatory and anti‐apoptotic properties in protection of the neonatal rat brain from LPS‐induced injury. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Inhibition of Müller glial cell division blocks regeneration of the light‐damaged zebrafish retina
Authors: Thummel Ryan , Kassen Sean C. , Montgomery Jacob E. , Enright Jennifer M. , Hyde David R. 
Published: December 2007

AbstractThe adult zebrafish retina possesses a robust regenerative response. In the light‐damaged retina, Müller glial cell divisions precede regeneration of rod and cone photoreceptors. Neuronal progenitors, which arise from the Müller glia, continue to divide and use the Müller glial cell processes to migrate to the outer nuclear layer and replace the lost photoreceptors. We tested the necessity of Müller glial cell division for photoreceptor regeneration. As knockdown tools were unavailable for use in the adult zebrafish retina, we developed a method to conditionally inhibit the expression of specific proteins by in vivo electroporation of morpholinos. We determined that two separate morpholinos targeted against the proliferating cell nuclear antigen (PCNA) mRNA reduced PCNA protein levels. Furthermore, injection and in vivo electroporation of PCNA morpholinos immediately prior to starting intense light exposure inhibited both Müller glial cell proliferation and neuronal progenitor marker Pax6 expression. PCNA knockdown additionally resulted in decreased expression of glutamine synthetase in Müller glia and Müller glial cell death, while amacrine and ganglion cells were unaffected. Finally, histological and immunological methods showed that long‐term effects of PCNA knockdown resulted in decreased numbers of Müller glia and the failure to regenerate rod photoreceptors, short single cones, and long single cones. These data suggest that Müller glial cell division is necessary for proper photoreceptor regeneration in the light‐damaged zebrafish retina and are consistent with the Müller glia serving as the source of neuronal progenitor cells in regenerating teleost retinas. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Behavioral and synaptic defects in C. elegans lacking the NK‐2 homeobox gene ceh‐28
Authors: Ray Paramita , Schnabel Ralf , Okkema Peter G. 
Published: December 2007

AbstractC. elegans pharyngeal behavior consists of two distinct types of muscle contractions, termed pumping and peristalsis. Pumping ingests and concentrates bacteria in the anterior pharyngeal lumen, and it is occasionally followed by a transient peristaltic contraction that carries ingested bacteria through the posterior pharyngeal isthmus. These behaviors are controlled by a small pharyngeal nervous system consisting of 20 neurons that is almost completely independent of the extra‐pharyngeal nervous system. The cholinergic motor neuron M4 controls peristalsis via synapses with the posterior isthmus muscles. Here we show that the NK‐2 family homeobox gene ceh‐28 is expressed in M4, where it regulates synapse assembly and peristalsis. ceh‐28 mutants exhibit frequent and prolonged peristalses, and treatment with agonists or antagonists of muscarinic acetylcholine receptors can phenocopy or suppress ceh‐28 mutant defects, respectively. Synapses in ceh‐28 mutant M4 cells are irregularly spaced and sized, and they are abnormally located along the full length of the isthmus. We suggest that CEH‐28 inhibits synaptogenesis, and that ceh‐28 mutant behavioral defects result from excessive or ectopic stimulation of muscarinic acetylcholine receptors in the isthmus muscles. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008