bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐Assembly and Dynamics of Polypeptides
Authors: Floudas George , Spiess Hans Wolfgang
Published: January 2009

This work highlights the results of recent efforts to understand the hierarchical self‐assembly and dynamics of polypeptides with the aid of different NMR techniques, X‐ray scattering, and dielectric spectroscopy. The concerted application of these techniques sheds light on the origin of the glass transition, the persistence of theα‐helical peptide secondary motif, and the effects of topology and packing on the type and persistence of secondary structures. With respect to the freezing of the dynamics at the liquid‐to‐glass temperature it was found that the origin of this effect is a network of defected hydrogen bonds. The presence of defected hydrogen‐bonded regions reduces the persistence length ofα‐helices. Block copolypeptides provide means to manipulate both the type and persistence of peptide secondary structures.

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Blow up for a Cauchy viscoelastic problem with a nonlinear dissipation of cubic convolution type
Authors: Yu Shengqi , Wang Mingxin , Liu Wenjun
Published: January 2009

In this paper, we consider a Cauchy viscoelastic problem with a nonlinear source of polynomial type and a nonlinear dissipation of cubic convolution type involving a singular kernel. Under suitable conditions on the initial data and the relaxation functions, it is proved that the solution of this particular problem blows up in finite time. Copyright © 2009 John Wiley & Sons, Ltd.
Magnetic resonance elastography with a phased‐array acoustic driver system
Authors: Mariappan Yogesh K. , Rossman Phillip J. , Glaser Kevin J. , Manduca Armando , Ehman Richard L.
Published: January 2009

Dynamic MR elastography (MRE) quantitatively maps the stiffness of tissues by imaging propagating shear waves in the tissue. These waves can be produced from intrinsic motion sources (e.g., due to cardiac motion), from external motion sources that produce motion directly at depth in tissue (e.g., amplitude‐modulated focused ultrasound), and from external actuators that produce motion at the tissue surface that propagates into the tissue. With external actuator setups, typically only a single transducer is used to create the shear waves, which in some applications might have limitations due to shadowing and attenuation of the waves. To address these limitations, a phased‐array acoustic driver system capable of applying independently controlled waveforms to each channel was developed and tested. It was found that the system produced much more uniform illumination of the object, improving the quality of the elastogram. It was also found that the accuracy of the stiffness value of any arbitrary region of interest could be improved by obtaining maximal shear wave illumination with the phased array capability of the system. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Variation in the shape of pulsed arterial spin labeling kinetic curves across the healthy human brain and its implications for CBF quantification
Authors: Gallichan Daniel , Jezzard Peter
Published: January 2009

Arterial spin labeling (ASL) uses proximally inverted blood water spins as an endogenous contrast agent to measure blood perfusion in tissue. In this work pulsed ASL was used to measure the kinetic curves of cerebral blood flow (CBF) across eight anatomically based regions of interest (ROIs) in five normal healthy subjects. CBF estimates based on these data were compared when obtained using a single inversion time versus fitting a kinetic model to all 10 measured inversion times. CBF estimates were also compared when fitting to the 10 inversion time data using a standard two‐parameter approach (CBF and bolus arrival time) or a more recently proposed three‐parameter model (CBF, bolus arrival time, and arrival time dispersion). Variations in the shape of the kinetic curve were found across the brain that were consistent across subjects. The arrival time in the occipital ROI was found to be long enough to lead to underestimation of the CBF when using a single inversion time of 1.5 s. In four out of the eight ROIs there was significant underestimation of CBF using the standard two‐parameter model compared to the three‐parameter approach. These results have important implications for the development of a robust, quantitative ASL protocol. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Eddy‐current compensated diffusion weighting with a single refocusing RF pulse
Authors: Finsterbusch Jürgen
Published: January 2009

A modification of the Stejskal‐Tanner diffusion‐weighting preparation with a single refocusing RF pulse is presented which involves three gradient lobes that can be adjusted to null eddy currents with any given decay rate to reduce geometric distortions in diffusion‐weighted echo‐planar imaging (EPI). It has a very similar compensation performance as the commonly used double‐spin‐echo preparation but (i) is less sensitive to flip angle imperfections, e.g. along the slice profile, and B1 inhomogeneities and (ii) can yield shorter echo times for moderate b values, notably for longer echo trains as required for higher spatial resolution. It therefore can provide an increased signal‐to‐noise ratio as is simulated numerically and demonstrated experimentally in water phantoms and the human brain for standard EPI (2.0 × 2.0 mm2) and high‐resolution EPI of inner field‐of‐views using 2D‐selective RF excitations (0.5 × 1.0 mm2). Thus, the presented preparation may help to overcome current limitations of diffusion‐weighted EPI, in particular at high static magnetic fields. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Non‐uniqueness of critical state line in compression and extension conditions
Authors: Yin Zhen‐Yu , Chang Ching S.
Published: January 2009

Experimental evidence has indicated that the critical state line determined from undrained compression tests is not identical to that determined from undrained extension tests. The purpose of this paper is to investigate a modelling method that accounts for the non‐uniqueness of critical state lines in the compression and the extension testing conditions. Conventional elastic–plastic cap models can predict only a unique critical state line for the compression and the extension tests. A new micromechanical stress–strain model is developed considering explicitly the location of critical state line. The model is then used to simulate undrained triaxial compression and extension tests performed on isotropically consolidated samples with different over‐consolidated ratios. The predictions are compared with experimental results as well as that predicted by models with kinematic hardening of yield surface. All simulations demonstrate that the proposed micromechanical approach is capable of modelling the undrained compression and the undrained extension tests. Copyright © 2009 John Wiley & Sons, Ltd.
A domain decomposition method for discontinuous Galerkin discretizations of Helmholtz problems with plane waves and Lagrange multipliers
Authors: Farhat Charbel , Tezaur Radek , Toivanen Jari
Published: January 2009

A nonoverlapping domain decomposition (DD) method is proposed for the iterative solution of systems of equations arising from the discretization of Helmholtz problems by the discontinuous enrichment method. This discretization method is a discontinuous Galerkin finite element method with plane wave basis functions for approximating locally the solution and dual Lagrange multipliers for weakly enforcing its continuity over the element interfaces. The primal subdomain degrees of freedom are eliminated by local static condensations to obtain an algebraic system of equations formulated in terms of the interface Lagrange multipliers only. As in the FETI‐H and FETI‐DPH DD methods for continuous Galerkin discretizations, this system of Lagrange multipliers is iteratively solved by a Krylov method equipped with both a local preconditioner based on subdomain data, and a global one using a coarse space. Numerical experiments performed for two‐ and three‐dimensional acoustic scattering problems suggest that the proposed DD‐based iterative solver is scalable with respect to both the size of the global problem and the number of subdomains. Copyright © 2009 John Wiley & Sons, Ltd.
Compact difference schemes for heat equation with Neumann boundary conditions
Authors: Sun Zhi‐Zhong
Published: January 2009

In this article, two recent proposed compact schemes for the heat conduction problem with Neumann boundary conditions are analyzed. The first difference scheme was proposed by Zhao, Dai, and Niu (Numer Methods Partial Differential Eq 23, (2007), 949–959). The unconditional stability and convergence are proved by the energy methods. The convergence order is O(τ2 + h2.5) in a discrete maximum norm. Numerical examples demonstrate that the convergence order of the scheme can not exceeds O(τ2 + h3). An improved compact scheme is presented, by which the approximate values at the boundary points can be obtained directly. The second scheme was given by Liao, Zhu, and Khaliq (Methods Partial Differential Eq 22, (2006), 600–616). The unconditional stability and convergence are also shown. By the way, it is reported how to avoid computing the values at the fictitious points. Some numerical examples are presented to show the theoretical results. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Finite element analysis of thermally coupled nonlinear Darcy flows
Authors: Zhu Jiang
Published: January 2009

We consider a coupled system describing nonlinear Darcy flows with temperature dependent viscosity and with viscous heating. We first establish existence, uniqueness, and regularity of the weak solution of the system of equations. Next, we decouple the coupled system by a fixed point algorithm and propose its finite element approximation. Finally, we present convergence analysis with an error estimate between continuous solution and its iterative finite element approximation.© 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010
Does perception of the childbirth experience predict women's early parenting behaviors?
Authors: Bryanton Janet , Gagnon Anita J. , Hatem Marie , Johnston Celeste
Published: January 2009

Evidence regarding the predictors of positive parenting behaviors in the early transition to parenting is inconsistent and limited. In this prospective, cohort study, we examined whether women's perceptions of their childbirth experience, as well as selected demographic, obstetrical, and psychosocial variables, predicted positive parenting behaviors at 1 month postpartum in 175 Canadian mothers. Women's birth experience did not predict early parenting behaviors, however being better educated and having a vaginal birth did. Excellent partner support and maternal mental health were also significantly associated with positive parenting at 1 month. Nurses have a responsibility to assess women for possible risks for sub‐optimal parenting, based on the predictors found, and intervene to enhance parenting behaviors. © 2009 Wiley Periodicals, Inc. Res Nurs Health 32:191–203, 2009
Besonderheiten der Pharmakotherapie bei Kindern. Gibt es eine Metamorphose der “therapeutischen Waisen”?
Authors: Vogt Winnie , Frobel Anne‐Kristina , Läer Stephanie
Published: January 2009

Unzureichende Informationen über die Besonderheiten der Arzneimitteltherapie im Kindesalter sind häufig Gründe von nicht effektiven Therapien und unerwünschten Arzneimittelwirkungen. Besonderheiten der Arzneimitteltherapie bei Kindern erschließen sich durch das Verständnis der Pharmakokinetik und der Pharmakodynamik im Wachstums‐ und Entwicklungsprozess des Kindes. Es gehört zur zentralen Aufgabe von Ärzten und Apothekern, diese Besonderheiten zu verstehen und sie zum Wohl des Patienten in die Arzneimitteltherapie einfließen zu lassen.
Arzneiformen für Kinder. Nach der EU‐Reform
Authors: Breitkreutz Jörg
Published: January 2009

Kindgerechte Arzneiformen sind eine Grundvoraussetzung für die effektive Behandlung von Krankheiten im Kindesalter. Bisher gibt es nur wenige Arzneimittel, die den Kriterien einer kindgerechten Zubereitung entsprechen. Die Gesetzesinitiativen in Europa und den USA haben die Forschung und Entwicklung von innovativen Arzneiformen und ‐zubereitungen stimuliert. Wegen der altersgruppenspezifischen Unterschiede ist die Entwicklung mehrerer Darreichungsformen erforderlich. Moderne kindgerechte Arzneiformen berücksichtigen die physiologischen Besonderheiten der pädiatrischen Subpopulationen, sind sicher und bequem einzunehmen und besitzen organoleptische Eigenschaften, die von den Kindern akzeptiert werden.
Regulatorische Aspekte der Zulassung von Arzneimitteln für Kinder. USA, Europa und Deutschland
Authors: Franken Andreas
Published: January 2009

Wir imitieren hier in Europa derzeit ein System, das in den USA seit über 40 Jahren gewachsen ist. Gleichzeitig versuchen wir, dieses System auf die Besonderheiten der europäischen Bürokratie‐ und Industrie‐Landschaft zuzuschneiden. Dabei war es die richtige Entscheidung, die Einführung über eine EG‐Verordnung zu vollziehen, deren Inhalte europaweit zur gleichen Zeit, in derselben Form, Gesetz sind und nicht mehr interpretiert werden. Kritik an diesen Vorgaben ist an der einen oder anderen Stelle durchaus angebracht. Nachbesserungen sind nicht einfach umzusetzen, aber dennoch möglich, wie das Beispiel der Kennzeichnung durch ein Symbol gezeigt hat. Dennoch ist die gesamte Entwicklung als großer Fortschritt zu betrachten, auch wenn es mit Sicherheit zu neuen, hohen Hürden bei der Finanzierung der pharmazeutischen Forschung kommt. Die resultierenden Forderungen an die pharmazeutischen Unternehmen, und hier besonders die kleinen und mittelständischen, sind sehr weitreichend, was die Pflege einer Zulassung, Nachlieferung von Daten an die Zulassungsbehörden und verpflichtende Vorlagen von pädiatrischen Prüfkonzepten bei Indikationserweiterungen, neuen Darreichungsformen oder Stärken betrifft. Es steht zu befürchten, dass eine finanzielle Kompensation durch die in der Verordnung vorgesehenen Anreize nicht erreicht werden wird.

Generell bleibt zu hoffen, dass mit dieser Verordnung tatsächlich eine Verbesserung in der Arzneimitteltherapie für Kinder und Jugendliche bewirkt wird und nicht die Forschung an neuen Arzneimitteln in Europa mit einem Hemmschuh versehen wurde, der viele gute Ideen durch bürokratische und finanzielle Hürden ausbremst. Auch wenn Europa sich mit dieser Verordnung hohe Ziele gesteckt hat, die mit Sicherheit Zugeständnisse von allen Seiten erfordern, sollten wir bei allen Diskussionen nie vergessen, dass es hier primär um das Wohlergehen unserer Kinder geht.
ZAK® – Zugelassene Arzneimittel für Kinder. Datenbank mit Kinderarzneimitteln
Authors: Schoettler Petra
Published: January 2009

Nur ein Bruchteil unserer Arzneimittel ist auch zur Anwendung bei Kindern zugelassen. Seit 2006 wird die gezielte Recherche nach Arzneimitteln für Patienten unter 18 Jahren erstmalig durch eine Datenbank unterstützt. Die Daten für ZAK® werden den Fachinformationen entnommen, die eine Zusammenfassung der zugelassenen Merkmale eines Arzneimittels enthalten.

Obwohl in der Fachinformation inzwischen Dosierungen für Kinder angegeben werden müssen, lassen formale und inhaltliche Mängel die Bestimmung der behandelbaren Altersgruppen nicht immer eindeutig zu. Zur Verbesserung der Arzneimittelsicherheit sollte deshalb in der Dosierungsanleitung das Alter in Zahlen angegeben werden, idealerweise bereits im Abschnitt Anwendungsgebiete.
Das In‐silico‐Child. Können Computer‐Simulationen klinisch‐pharmakokinetische Studien ersetzen?
Authors: Willmann Stefan
Published: January 2009

Die Erwachsenen‐Dosis eines Medikaments (pro Kilogramm Körpergewicht), einem Kind verabreicht, kann abhängig vom Alter des Kindes zu sub‐therapeutischen oder auch toxischen Spiegeln führen. Darum ist die Prüfung der Sicherheit und Wirksamkeit eines Medikaments in Kindern im Rahmen von klinischen Studien Voraussetzung für die Zulassung für pädiatrische Indikationen.

Mithilfe des Computers lassen sich klinische Studien in pädiatrischen Patientenpopulationen “virtuell” durchführen, bevor die Substanz tatsächlich in Kindern verabreicht wird. Die Ergebnisse dieser virtuellen Studien können dann zur Optimierung des Studiendesigns für die reale Patientenpopulation herangezogen werden, beispielsweise durch eine A‐priori‐Berechnung der optimalen altersabhängigen Dosierung oder durch die Bestimmung der optimalen Blutentnahmezeitpunkte bei den Studienteilnehmern.

Auch wenn virtuelle klinische Studien in Kindern reale Studien nicht vollständig ersetzen können, so ist es ein realistisches Ziel, die Größe einer pädiatrischen Studienpopulation durch begleitende Computer‐Simulationen – bei gleicher oder gar besserer Aussagekraft – deutlich zu verkleinern.
Ethische Aspekte der Durchführung von klinischen Studien an Kindern. Eine Instrumentalisierung Wehrloser?
Authors: Taupitz Jochen
Published: January 2009

Gruppennützige Forschung mit Kindern bedeutet im Ergebnis keineswegs per se eine Instrumentalisierung Wehrloser. Gruppennützige Forschung mit Kindern kann freilich nur dann zulässig sein, wenn sie wegen Alternativlosigkeit zwingend notwendig ist und dem Kind keine substanziellen Nachteile zufügt. Vor allem aber muss die Einwilligung des gesetzlichen Vertreters vorliegen, weil er derjenige ist, der von Rechts wegen dafür zu sorgen hat, dass Einwilligungsunfähigen die Teilnahme am Rechtsverkehr überhaupt erst ermöglicht wird. Zudem ist eine altersgerechte Aufklärung des Kindes erforderlich und darf sein natürlicher Wille nicht übergangen werden, muss ferner eine Verfahrenskontrolle durch eine unabhängige und interdisziplinär zusammengesetzte Ethikkommission vorgeschaltet und sollte “vor Ort” eine unabhängige Vertrauensperson als Ansprechpartner und Kontrollperson verfügbar sein. Nur durch dieses Zusammenwirken von Schutzmechanismen kann ein ausreichendes Schutzniveau sichergestellt werden, ohne die Gruppe der Kinder zugleich zu Forschungswaisen zu machen.
Arzneimittelanwendung bei und mit Kindern. Nein, meine Tropfen nehm' ich nicht!
Authors: Schäfer Constanze
Published: January 2009

Viele Eltern machen die Erfahrung: Einem Kind ein Arzneimittel zu geben kann zu einer Herausforderung werden. Wer noch nie einem Säugling ein Zäpfchen verabreicht hat, wird dies beim ersten Mal sicher mit erhöhtem Puls tun. Diese Nervosität, Angst oder Unsicherheit der Eltern überträgt sich auf die Kinder, was die Verabreichung nicht einfacher macht. Da zudem viele Hersteller sich nur unzureichend um kindgerechte Arzneiformen und Zubereitungen bemühen, muss häufig mit inadäquaten Präparaten therapiert werden. Patentlösungen gibt es nicht. Der folgende Beitrag möchte deshalb Anregungen für die Beratung von Eltern geben beziehungsweise für spezielle Probleme sensibilisieren.
Pflanzliche Arzneimittel für Kinder. Fencheltee und Co.
Authors: Knöss Werner , Alban Susanne
Published: January 2009

Die Anwendung pflanzlicher Arzneimittel bei Kindern und Jugendlichen ist in Deutschland weit verbreitet und ein wesentlicher Bestandteil der Selbstmedikation. Aus der traditionellen Nutzung resultiert die Erwartung einer guten Wirksamkeit und Verträglichkeit. Das vorhandene Datenmaterial aus klinischen Studien ist jedoch insgesamt begrenzt. Daher sind bei der öffentlichen und Patienten bezogenen Information die Möglichkeiten und Grenzen der Phytotherapie sachgerecht zu vermitteln. Es ist zu befürchten, dass aufgrund der Entwicklung der letzten Jahre und im Rahmen der europäischen Harmonisierung sowie auch trotz der EU‐Verordnung über Kinderarzneimittel die Verfügbarkeit pflanzlicher Arzneimittel für diese Altersgruppe nicht verbessert wird.

Es ist zu diskutieren, ob es spezifischer Regelungen und Anreize bedarf, um bessere Daten für die therapeutische Nutzung pflanzlicher Arzneimittel bei Kindern und Jugendlichen zu generieren und die Optimierung von Darreichungsformen und galenischen Formulierungen zu stimulieren. Die vorhandenen methodischen Möglichkeiten für Wirksamkeitsbelege müssen daraufhin geprüft werden, ob sie speziell für pflanzliche Arzneimittel weiterentwickelt oder durch zusätzliche Instrumente ergänzt werden können. Insbesondere für die Registrierung traditioneller pflanzlicher Arzneimittel muss das im deutschsprachigen Europa vorhandene, aber praktisch nicht nach aktuellen Arzneimittelanforderungen dokumentierte Erfahrungswissen systematisch mit wissenschaftlichen Methoden aufbereitet und dargestellt werden.

In jedem Fall ist die Grundvoraussetzung für die Anwendung pflanzlicher Arzneimittel eine definierte Qualität der Produkte und eine fachlich hochwertige Ausbildung sowohl der Apotheker/innen als auch der Ärzte/innen. Für die Selbstmedikation sind transparente und qualifizierte Informationen erforderlich, die insbesondere auch die Grenzen der Selbstmedikation herausstellen.

Grundlage dieses Beitrages ist ein Symposium “Pflanzliche Arzneimittel in der Phytotherapie”, das von der Fachgruppe Pharmazeutische Biologie der Deutschen Pharmazeutischen Gesellschaft während der Jahrestagung 2008 in Bonn organisiert wurde (Präsentationen von Prof. Dr. Dorsch, Dr. Genau, Prof. Dr. Häberlein, Dr. Lehmann, Dr. Schell und Dr. Wegener sowie umfangreiche Diskussion).
Thymian‐Efeu‐Kombination nutzt Synergie‐Effekte in Wirkung und Wissenschaft
Authors: Wagner Ute
Published: January 2009

Moderne pflanzliche Arzneimittel können auch wissenschaftlich eine Vorreiterrolle in ihren Anwendungsgebieten übernehmen. Das macht für die Therapie der akuten Bronchitis die Kombination einer placebokontrollierten, randomisierten klinischen Studie mit Erwachsenen mit einer großen Anwendungsbeobachtung an Kindern deutlich. Die Verknüpfung der Daten machte die Neuzulassung des Hustensaftes aus Thymian‐ und Efeu‐Spezialextrakten schon für Kleinkinder ab 1 Jahr möglich.
siRNAs – Dein Freund und Helfer?
Authors: Zündorf Ilse , Dingermann Theo
Published: January 2009

2002 galten sie beim renommierten Wissenschaftsjournal Science als “Durchbruch des Jahres”, 2006 verhalfen sie den Forschern Andrew Z. Fire und Craig C. Mello zum Nobelpreis und jetzt postuliert eine kanadische Forschergruppe, dass die so oft gepriesene Wirksamkeit in verschiedenen, krankheitsrelevanten Tiermodellen nur aufgrund einer unspezifischen Stimulation des Immunsystems zustande gekommen ist.
Differential protein expression in heart in UT‐B null mice with cardiac conduction defects
Authors: Yu Hao , Meng Yan , Wang Li‐Shun , Jin Xian , Gao Li‐Fang , Zhou Lei , Ji Kun , Li Yang , Zhao Li‐Juan , Chen Guo‐Qiang , Zhao Xue‐Jian , Yang Baoxue
Published: January 2009

Cardiac conduction defects were found in transgenic mice deficient in urea transporter UT‐B. To investigate the molecular mechanisms of the conduction defects caused by UT‐B deletion, we studied the protein expression profiles of heart tissue (comprising most conduction system) in wild‐typeversusUT‐B null mice at different ages. By two‐dimensional electrophoresis‐based comparative analysis, we found that more than dozen proteins were modulated (>two‐fold) in the myocardium of UT‐B null mice. Out of these modulated proteins, troponin T (TNNT2) presented significant changes in UT‐B null mice at early stage prior to the development of P‐R interval elongation, while the change of atrial natriuretic peptide (ANP) occurred only at late stage in UT‐B null mice that had the AV block. These data indicate that UT‐B deletion caused the dynamic expression regulation of TNNT2 and ANP, and these proteins may provide new clues to investigate the molecular events involved in cardiac conduction.
A bioanalytical method for the proteome wide display and analysis of protein complexes from whole plant cell lysates
Authors: Remmerie Noor , Roef Luc , Van De Slijke Eveline , Van Leene Jelle , Persiau Geert , Eeckhout Dominique , Stals Hilde , Laukens Kris , Lemière Filip , Esmans Eddy , Van Onckelen Harry , Inzé Dirk , De Jaeger Geert , Witters Erwin
Published: January 2009

While protein interaction studies and protein network modeling come to the forefront, the isolation and identification of protein complexes in a cellular context remains a major challenge for plant science. To this end, a nondenaturing extraction procedure was optimized for plant whole cell matrices and the combined use of gel filtration and BN‐PAGE for the separation of protein complexes was studied. Hyphenation to denaturing electrophoresis and mass spectrometric analysis allows for the simultaneous identification of multiple (previously unidentified) protein interactions in single samples. The reliability and efficacy of the technique was confirmed (i) by the identification of well‐studied plant protein complexes, (ii) by the presence of nonplant interologs for several of the novel complexes (iii) by presenting physical evidence of previously hypothetical plant protein interactions and (iv) by the confirmation of found interactions using co‐IP. Furthermore practical issues concerning the use of this 2‐D BN/SDS‐PAGE display method for the analysis of protein–protein interactions are discussed.
Chitosan treatment induces changes of protein expression profile and stilbene distribution in Vitis vinifera cell suspensions
Authors: Ferri Maura , Tassoni Annalisa , Franceschetti Marina , Righetti Laura , Naldrett Mike J. , Bagni Nello
Published: January 2009

Polyphenols, including stilbenes and flavonoids, are an essential part of human diet and constitute one of the most abundant and ubiquitous groups of plant secondary metabolites, and their level is inducible by stress, fungal attack or biotic and abiotic elicitors. Proteomic analysis of Vitis vinifera (L.) cultivar (cv.) Barbera grape cell suspensions, showed that the amount of 73 proteins consistently changed in 50 μg/mL chitosan‐treated samples compared with controls, or between the two controls, of which 56 were identified by MS analyses. In particular, de‐novo synthesis and/or accumulation of stilbene synthase proteins were promoted by chitosan which also stimulated trans‐resveratrol endogenous accumulation and decreased its release into the culture medium. No influence was shown on cis‐resveratrol. There was no effect on the accumulation of total resveratrol mono‐glucosides (trans‐ and cis‐piceid and trans‐ and cis‐resveratroloside). Throughout the observation period the upregulation of phenylalanine ammonia lyase, chalcone synthase, chalcone‐flavanone isomerase (CHI) transcript expression levels well correlated with CHI protein amount and with the accumulation of anthocyanins. Chitosan treatment strongly increased the expression of eleven proteins of the pathogenesis related protein‐10 family, as well as their mRNA levels.
Proteomic profiling of antisense‐induced exon skipping reveals reversal of pathobiochemical abnormalities in dystrophic mdx diaphragm
Authors: Doran Philip , Wilton Steve D. , Fletcher Sue , Ohlendieck Kay
Published: January 2009

The disintegration of the dystrophin–glycoprotein complex represents the initial pathobiochemical insult in Duchenne muscular dystrophy. However, secondary changes in signalling, energy metabolism and ion homeostasis are probably the main factors that eventually cause progressive muscle wasting. Thus, for the proper evaluation of novel therapeutic approaches, it is essential to analyse the reversal of both primary and secondary abnormalities in treated muscles. Antisense oligomer‐mediated exon skipping promises functional restoration of the primary deficiency in dystrophin. In this study, an established phosphorodiamidate morpholino oligomer coupled to a cell‐penetrating peptide was employed for the specific removal of exon 23 in the mutated mouse dystrophin gene transcript. Using DIGE analysis, we could show the reversal of secondary pathobiochemical abnormalities in the dystrophic diaphragm following exon‐23 skipping. In analogy to the restoration of dystrophin, β‐dystroglycan and neuronal nitric oxide synthase, the muscular dystrophy‐associated differential expression of calsequestrin, adenylate kinase, aldolase, mitochondrial creatine kinase and cvHsp was reversed in treated muscle fibres. Hence, the re‐establishment of Dp427 coded by the transcript missing exon 23 has counter‐acted dystrophic alterations in Ca2+‐handling, nucleotide metabolism, bioenergetic pathways and cellular stress response. This clearly establishes the exon‐skipping approach as a realistic treatment strategy for diminishing diverse downstream alterations in dystrophinopathy.
Managing the Data Explosion A Report on the HUPO‐PSI Workshop August 2008, Amsterdam, The Netherlands
Authors: Orchard Sandra , Hoogland Christine , Bairoch Amos , Eisenacher Martin , Kraus Hans‐Joachim , Binz Pierre‐Alain
Published: January 2009

The plenary session of the Proteomics Standards Initiative (PSI) of the Human Proteome Organisation at the 7th annual HUPO world congress updated the delegates on the current status of the ongoing work of this group. The release of the new MS interchange format, mzML, was formally announced and delegates were also updated on the advances in the area of molecular interactions, protein separations, proteomics informatics and also on PEFF, a common sequence database format currently under review in the PSI documentation process. Community input on this initiative was requested. Finally, the impact these new data standards are having on the data submission process, which increasingly is an integral part of the publication process, was reviewed and discussed.
Reactions of (1‐nitroethenyl)sulfonylbenzene, a nitroethene derivative geminally substituted by a second W‐group
Authors: Wade Peter A. , Murray James K. , Pipic Alma , Arbaugh Robert J. , Jeyarajasingam Amutha
Published: January 2009

Nitroaldol reaction of phenylsulfonylnitromethane with formaldehyde affords a mixture of 2,4‐dinitro‐2,4‐bis(phenylsulfonyl)butan‐1‐ol and 2,4‐dinitro‐2,4‐ bis(phenylsulfonyl)pentane‐1,5‐diol. Treatment of this mixture with base followed by reacidification affords 1,1'‐[(1,3‐dinitro‐1,3‐propanediyl)bis(sulfonyl)]bis(benzene) as a mixture of (R*, R*) and (R*, S*)‐diastereomers from which the (R*, S*)‐diastereomer can be obtained pure. The intermediate in the nitroaldol reaction is (1‐nitroethenyl)sulfonylbenzene and, if dienes are present, additional products are also obtained. If either (E)‐2‐methyl‐1,3‐pentadiene or 1‐(1‐methylethenyl)cyclohexene are present, typical Diels‐Alder adducts are obtained with the major isomers explainable by assuming a transition state in which the nitro group is endo. If furan is present, its formal conjugate addition product, 2‐[2‐nitro‐2‐(phenylsulfonyl)ethyl]furan, is formed. If cyclooctatetraene is present, it first dimerizes and then affords isomeric Diels‐Alder cycloadducts of the dimer. Semiempirical calculations comparing the LUMO energies of (1‐nitroethenyl)sulfonylbenzene to the corresponding trans‐1,2 isomer are presented to explain relative reactivity of 1,1‐ and 1,2‐disubstituted dienophiles. Copyright © 2009 John Wiley & Sons, Ltd.
A DFT study on the (2 + 3) cycloaddition reactions of 2‐nitropropene‐1 with Z‐C, N‐diarylnitrones
Authors: Jasiński Radomir , Wąsik Katarzyna , Mikulska Maria , Barański Andrzej
Published: January 2009

B3LYP/6‐31G* calculations for competing (2 + 3)‐cycloaddition pathways for 2‐nitropropene‐1 (1) to Z‐C, N‐diarylnitrones (2a–e) suggest a concerted reaction mechanism. However, the results point to the strongly asymmetric nature of transition complexes. Increasing polarity of the reaction environment and presence of electron‐donating substituents in the nitrone phenyl rings contribute to the higher asymmetry of these structures. Copyright © 2009 John Wiley & Sons, Ltd.
Kinetic study of nitrosation of methylformamide
Authors: Fernández I. , Hervés P. , Parajó M. , Pérez‐Juste J.
Published: January 2009

Nitrosation of methylformamide (MFA) has been studied kinetically. The results obtained show that the reaction rate is first order with respect to both the MFA and proton concentration. The absence of catalysis by nucleophilic anions and the observed general base catalysis is interpreted in terms of formation of a protonated nitrosamide intermediate, being the proton transfer the slow step of the process. The primary solvent isotope effect observed corroborates this mechanism. From this study, we were able to obtain the values of the rate constants for the nitrosation process. The catalytic constants in the presence of buffers were also obtained and the analysis of the Brönsted slopes suggests a process with a transition state more similar to the reactants than the products. The absence of electron donating groups in MFA leads to a very low value of the bimolecular rate constant of the nitrosation reaction. Copyright © 2009 John Wiley & Sons, Ltd.
Long distance structural consequences of H‐bonding: the case of complexes ofpara‐substituted phenol derivatives
Authors: Szatyłowicz Halina , Krygowski Tadeusz M.
Published: January 2009

H‐bonded complexes ofp‐X‐PhOH/p‐X‐PhO−with fluoride and hydrofluoric acid (X = OH, H, NO2) were subject of optimization (by means of B3LYP/6‐311+G**) for gradually changed O···F distance fromdO···F = 4.0 Å down to (i) the distance of the proton transfer from the hydroxyl group to fluoride leading to O−···HF interaction and (ii) fully optimized system (O−···HF type). In this way, we simulate gradual changes of H‐bond strength estimating simultaneously the energy of interaction,Eint, energy of deformation,Edef, and the binding energy,Etot. The obtained geometrical parameters allow us to show that H‐bond formation causes substantial changes in geometry, even at so distant parts of the system as the ring and bond length inpara‐substituents (OH and NO2). All these changes are monotonically dependent on interaction and deformation energies. Copyright © 2009 John Wiley & Sons, Ltd.
Optical properties of a novel fluorene‐based thermally stable conjugated polymer containing pyridine and unsymmetric carbazole groups
Authors: Liaw Der‐Jang , Wang Kun‐Li , Kang En‐Tang , Pujari Sidharam Pundlik , Chen Min‐Hung , Huang Ying‐Chi , Tao Bo‐Cheng , Lee Kueir‐Rarn , Lai Juin‐Yih
Published: January 2009

A new diiodo monomer containing heterocyclic pyridine and carbazole groups was synthesized via Chichibabin reaction and used in the preparation of a conjugated polymer via Suzuki coupling approach. The conjugated polymer was highly soluble in common organic solvents such as NMP, THF, dichloromethane, chloroform, toluene, xylene, and benzene at room temperature. The polymer had high glass transition temperature at 191 °C and Td10 at 434 °C in nitrogen atmosphere. The pristine polymer exhibited the UV–vis maximum absorption at 355 nm and shifted to 420 nm after protonation. The emission of the polymer in THF solution changed from the blue region with maximum peak at 400 nm to the yellow region with maximum peak at 540 nm after protonated by HCl, and the intensity of emission depended on the concentration of acid. The polymer also showed electrochromic behavior under applied voltage. The emission color of the polymer film changed from blue (435 nm) to yellow (570 nm) when 2.5 V bias voltage was applied. The polymer also exhibited write‐once and read‐many‐times (WORM) polymer memory effect with tristable states. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 991–1002, 2009
Synthesis and photovoltaic properties of poly(p‐phenylenevinylene) derivatives containing oxadiazole
Authors: Wen Shanpeng , Pei Jianing , Zhou Yinhua , Xue Lili , Xu Bin , Li Yaowen , Tian Wenjing
Published: January 2009

A novel poly(p‐phenylenevinylene) PPV‐based copolymer (3C‐OXD‐PPV) with electron‐deficient oxadiazole segments as the side chain has been successfully synthesized through the Gilch polymerization. The obtained copolymer is soluble in common organic solvents such as chloroform, tetrahydronfuran, and 1,1,2,2‐tetrachloroethane. The copolymer was characterized by 1H NMR, elemental analysis and GPC. TGA measurement of the copolymer shows it has good thermal stability with decomposition temperature higher than 350 °C. The absorption, electrochemical properties of the 3C‐OXD‐PPV were investigated and also compared with the properties of MEH‐PPV. The HOMO and LUMO levels of 3C‐OXD‐PPV were estimated from the electrochemical cyclic voltammograms. Bulk‐heterojunction PVCs were fabricated by using 3C‐OXD‐PPV blended PCBM as an active layer. The PCE of the PVC is 1.60% under 100 mW cm−2 AM 1.5 illumination, which indicates that 3C‐OXD‐PPV is a potential candidate for the application of polymer PVC. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1003–1012, 2009
Perfluorocarbon‐loaded shell crosslinked knedel‐like nanoparticles: Lessons regarding polymer mobility and self‐assembly
Authors: Nyström Andreas M. , Bartels Jeremy W. , Du Wenjun , Wooley Karen L.
Published: January 2009

Reversible addition‐fragmentation chain transfer polymerization was employed to synthesize a set of copolymers of styrene (PS) and 2,3,4,5,6‐pentafluorostyrene (PPFS), as well as block copolymers with tert‐butyl acrylate (PtBA)‐b‐PS‐co‐PPFS, with control over molecular weight and polydispersity. It was found that the copolymerization of styrene and PFS allowed for the preparation of gradient copolymers with opposite levels of monomer consumption, depending on the feed ratio. Conversion to amphiphilic block copolymers, PAA‐b‐(PS‐co‐PPFS), by removing the protecting groups was followed by fitting with monomethoxy poly(ethylene glycol) chains. Solution‐state assembly and intramicellar crosslinking afforded shell crosslinked knedel‐like (SCK) block copolymer nanoparticles. These fluorinated nanoparticles (ca. 20 nm diameters) were studied as potential magnetic resonance imaging (MRI) contrast agents based on the 19F‐nuclei; however, it was found that packaging of the hydrophobic fluorinated polymers into the core domain restricted the mobility of the chains and prohibited 19F NMR spectroscopy when the particles were dispersed in water without an organic cosolvent. Packing of perflouro‐15‐crown‐5‐ether (PFCE) into the polymer micelle was demonstrated with good uptake efficiency; however, it was necessary to swell the core with a good solvent (DMSO) to increase the mobility and observe the 19F NMR signal of the PFCE. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1023–1037, 2009
Synthesis and characterization of sulfonated‐fluorinated, hydrophilic‐hydrophobic multiblock copolymers for proton exchange membranes
Authors: Yu Xiang , Roy Abhishek , Dunn Stuart , Badami Anand S. , Yang Juan , Good Alec S. , McGrath James E.
Published: January 2009

Hydrophilic/hydrophobic block copolymers as proton exchange membranes (PEMs) has become an emerging area of research in recent years. These copolymers were obtained through moderate temperature (∼ 100 °C) coupling reactions, which minimize the ether‐ether interchanges between hydrophobic and hydrophilic telechelic oligomers via a nucleophilic aromatic substitution mechanism. The hydrophilic blocks were based on the nucleophilic step polymerization of 3,3′‐disulfonated, 4,4′‐dichlorodiphenyl sulfone with an excess 4,4′‐biphenol to afford phenoxide endgroups. The hydrophobic (fluorinated) blocks were largely based on decafluoro biphenyl (excess) and various bisphenols. The copolymers were obtained in high molecular weights and were solvent cast into tough membranes, which had nanophase separated hydrophilic and hydrophobic regions. The performance and structure‐property relationships of these materials were studied and compared to random copolymer systems. NMR results supported that the multiblock sequence had been achieved. They displayed superior proton conductivity, due to the ionic proton conducting channels formed through the self‐assembly of the sulfonated blocks. The nano‐phase separated morphologies of the copolymer membranes were studied and confirmed by atomic force microscopy. Through control of a variety of parameters, including ion exchange capacity and sequence lengths, performances as high, or even higher than those of the state‐of‐the‐art PEM, Nafion, were achieved. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1038–1051, 2009
Ruthenium‐incorporated, metathesis‐active polyacetylene
Authors: Sherwood Danielle E. Schuehler , Williams Joseph E. , Sponsler Michael B.
Published: January 2009

Two olefin metathesis methods have been developed for the preparation of metal‐incorporated polyacetylene (MIPA) with high levels of covalently attached ruthenium complex. Treatment of freshly prepared, porous polyacetylene (PA) formed by polymerization of acetylene by the metathesis catalyst (H2IMes)RuCl2(CHPh)(3‐bromopyridine)2 (G2B) with additional G2B resulted in the incorporation of the ruthenium complex into the solid polymer in levels up to 75% by mass, giving two‐step MIPA (MIPA2). Alternatively, single‐step MIPA (MIPA1) samples with similar levels (up to 79% by mass) of ruthenium incorporation were obtained by polymerization of acetylene with highly concentrated solutions of G2B, and the resulting materials formed fine suspensions in CH2Cl2. A variety of experiments confirmed that both the methods give materials with ruthenium covalently attached to PA chains. Shiny, tough MIPA films were obtained by pressing the black powders obtained by either method. Some MIPA properties were dependent on the amount of metal incorporation, but even samples with high incorporation levels mimicked untreated PA in many respects. MIPA1, but not MIPA2, was made electrically conductive by doping with iodine. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1061–1072, 2009
Thermally degradable maleimides for reworkable adhesives
Authors: Zhang Xinnan , Chen Gang‐Chi , Collins Andrew , Jacobson Solomon , Morganelli Paul , Dar Yadunandan L. , Musa Osama M.
Published: January 2009

New thermosetting materials were developed for reworkable adhesive applications by introducing acetal ester groups as thermally degradable linkages into maleimide compounds. The synthesis of compounds containing maleimide functionality and acetal ester linkages was conducted by a one‐step neat reaction from commercially available materials. The polymerization process and thermal degradation of the synthesized materials were studied. It was found that the acetal ester linkage degraded rapidly above 225 °C, and introduction of this linkage into the adhesive formulation led to improved reworkability of adhesively bonded substrates. A mechanism for reworkability was proposed based on the insight provided by experimental and modeling work. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1073–1084, 2009
Relevance of a prereaction for the in situ NMP of styrene using the C‐Phenyl‐N‐tert‐butylnitrone/2,2′‐azobis(isobutyronitrile) pair
Authors: Sciannamea Valérie , Catala Jean‐Marie , Jerome Robert , Jérôme Christine , Detrembleur Christophe
Published: January 2009

In this article, we compare two routes for carrying out in situ nitroxide‐mediated polymerization of styrene using the C‐phenyl‐N‐tert‐butylnitrone (PBN)/2,2′‐azobis(isobutyronitrile) (AIBN) pair to identify the best one for an optimal control. One route consists in adding PBN to the radical polymerization of styrene, while the other approach deals with a prereaction between the nitrone and the free radical initiator prior to the addition of the monomer and the polymerization. The combination of ESR and kinetics studies allowed demonstrating that when the polymerization of styrene is initiated by AIBN in the presence of enough PBN at 110 °C, fast decomposition of AIBN is responsible for the accumulation of dead polymer chains at the early stages of the polymerization, in combination with controlled polystyrene chains. On the other hand, PBN acts as a terminating agent at 70 °C with the formation of a polystyrene end‐capped by an alkoxyamine, which is not labile at this temperature but that can be reactivated and chain‐extended by increasing the temperature. Finally, the radical polymerization of styrene is better controlled when the nitrone/initiator pair is prereacted at 85 °C for 4 h in toluene before styrene is added and polymerized at 110 °C. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1085–1097, 2009
Core‐shell nanoparticles with hyperbranched poly(arylene‐oxindole) interiors
Authors: Kowalczuk Agnieszka , Vandendriessche Annelies , Trzebicka Barbara , Mendrek Barbara , Szeluga Urszula , Cholewiński Grzegorz , Smet Mario , Dworak Andrzej , Dehaen Wim
Published: January 2009

Core‐shell type star polymers composed of poly(tert‐butyl acrylate) (poly(t‐BuA)) arms and 100% hyperbranched poly(arylene‐oxindole) interiors were synthesized via the “core‐first” method. Atom transfer radical polymerization of t‐BuA initiated by 2‐bromopropionyl terminal groups of the hyperbranched core was applied for the synthesis of the stars. The resultant star structures were characterized by gel permeation chromatography with triple detection. Polymers of molar masses Mn up to 1.68 × 105 g/mol were obtained. The obtained star polymers compared with the linear counterparts of the same molar mass have a much more compact structure in solution. The intrinsic viscosities of the stars are also significantly lower than their linear counterparts. Light scattering experiments were performed to provide information about the size of these macromolecules in solution. Preliminary characterization of the thermal properties of these novel materials is also reported. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1120–1135, 2009
A new route to acrylate oils: Crosslinking and properties of acrylate triglycerides from high oleic sunflower oil
Authors: de Espinosa L. Montero , Ronda J. C. , Galià M. , Cádiz V.
Published: January 2009

Triglycerides with acrylate functionality were prepared from a new route that involves the singlet oxygen photooxygenation of high oleic sunflower oil and further reduction of the resulting hydroperoxide derivatives to a mixture of secondary allylic alcohols. These unsaturated alcohols can be further reduced to saturated alcohols. These two new hydroxyl‐containing triglycerides were functionalized as acrylate esters and radically crosslinked in presence of different amounts of pentaerythritol tetraacrylate. The crosslinking reactions were followed by FTIR spectroscopy and the thermal properties of the final materials were evaluated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1159–1167, 2009
Controlled synthesis of trifluoropropylmethylsiloxane–dimethylsiloxane gradient copolymers by anionic ROP of cyclotrisiloxanes
Authors: Cypryk Marek , Delczyk BogumiŁa , Juhari Azhar , Koynov Kaloian
Published: January 2009

Kinetics of the anionic ring opening copolymerization of 2,4,6‐tris(3,3,3‐trifluoropropyl)‐2,4,6‐trimethylcyclotrisiloxane (F3) with hexamethylcyclotrisiloxane (D3) was studied in THF using BuLi as the initiator. The apparent reactivity ratios were estimated by computer simulation to r = 0.10 ± 0.02, r = 51.8 ± 5.5, which were used to predict the copolymer composition. As a result of so much different reactivities, simultaneous copolymerization leads to copolymers of blocky structure containing a narrow intermediate fragment with gradient distribution of siloxane units. Polymers having more uniform distribution of the trifluoropropyl groups along the chain were obtained by the semibatch process, adding F3 to the polymerization of less reactive D3. The resulted copolymers were characterized by SEC chromatography, 29Si NMR, DSC, DMA, and SAXS. Thermal and mechanical properties of the copolymers obtained by simultaneous copolymerization were similar to those of block copolymers. Only the copolymers obtained by semibatch method showed properties typical for gradient copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1204–1216, 2009