bluuebunny/crossref_metadata_2025 huggingface dataset:
Desarrollo de una aplicación ontológica para evaluar el mercado de trabajo español en Biblioteconomía y Documentación
Authors: Moreiro Jose Antonio , Sánchez-Cuadrado Sonia , Morato Jorge , Moreno Valentín
Published: February 2009

La tarea de evaluar la adecuación de las habilidades y competencias profesionales de los estudiantes de Biblioteconomía y Documentación es necesaria para el diseño de los planes de estudio de la especialidad. Sin embargo, esta labor conlleva un gran esfuerzo a los investigadores. Para facilitar el estudio se ha diseñado una metodología que simplifica su estudio periódico. Para validar la metodología se ha recopilado un corpus con los planes de estudio de la titulación y otro corpus formado por ofertas de empleo. A partir del corpus procedente de los planes de estudio se ha creado un tesauro que muestra la terminología del dominio. Con dicho tesauro se ha indizado automáticamente las ofertas de empleo. La comparación estadística entre los términos de las ofertas y los planes de estudio denota necesidades y carencias en la adecuación de los planes de estudio a las ofertas de trabajo. La metodología empleada permite presentar, de forma coherente y periódica la adecuación de planes de estudios a las demandas del mercado laboral. La comparación con estudios previos ha validado la idoneidad de la propuesta.
Defocused Wide‐field Imaging Unravels Structural and Temporal Heterogeneity in Complex Systems
Authors: Dedecker Peter , Muls Benoît , Deres Ania , Uji‐i Hiroshi , Hotta Jun‐ichi , Sliwa Michel , Soumillion Jean‐Philippe , Müllen Klaus , Enderlein Jörg , Hofkens Johan
Published: February 2009

Today's miniature devices and biological systems share the fact that their dynamics and properties cannot be understood in terms of macroscopic concepts, but require a thorough understanding of the nanoscale structuring. This structuring is often very heterogeneous, both in time and in space, and is difficult or impossible to resolve with traditional approaches. In this Progress Report, we will discuss how single‐molecule microscopy—and defocused wide‐field imaging in particular—can be used to shed light on these phenomena.
Efficient Solid‐Phase Synthesis of Sulfotyrosine Peptides using a Sulfate Protecting‐Group Strategy
Authors: Ali Ahmed M. , Taylor Scott D.
Published: February 2009

Zweierlei Schutzgruppen: Eine effiziente Fmoc‐Festphasensynthese (Fmoc‐SPPS) von Sulfotyrosin(sY)‐Peptiden gelingt durch Einführen von sY‐Resten als Dichlorvinyl(DCV)‐geschützte Sulfodiester, wobei die Fmoc‐Gruppe mit 2‐Methylpiperidin entfernt wird. Nach Abspaltung der übrigen Schutzgruppen wurden die sY‐Peptide durch milde Hydrogenolyse der DCV‐Gruppe in guten Ausbeuten erhalten.

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Electrochemical Gene‐Function Analysis for Single Cells with Addressable Microelectrode/Microwell Arrays
Authors: Lin Zhenyu , Takahashi Yasufumi , Murata Tatsuya , Takeda Michiaki , Ino Kosuke , Shiku Hitoshi , Matsue Tomokazu
Published: February 2009

Zellen als Individualisten: Eine adressierbare elektrochemische Funktionseinheit mit Elektroden in orthogonalen Zeilen und Spalten wurde entworfen, um die Proteinexpression in einzelnen gentechnisch veränderten Zellen zu verfolgen. Aus dem Verhalten von HeLa‐Zellen, die mit einem Plasmidvektor für sekretierte alkalische Phosphatase transfiziert waren, beim Durchfahren von Redoxzyklen ging der unterschiedliche Expressionsgrad des Enzyms hervor.

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Efficient Solid‐Phase Synthesis of Sulfotyrosine Peptides using a Sulfate Protecting‐Group Strategy
Authors: Ali Ahmed M. , Taylor Scott D.
Published: February 2009

Double protection: Efficient Fmoc‐based solid‐phase synthesis (SPPS) of sulfotyrosine (sY) peptides is achieved by incorporating the sY residue(s) as a dichlorovinyl‐protected (DCV) sulfodiester(s) and using 2‐methylpiperidine for Fmoc removal. After removal of the other protecting groups, the DCV group could be cleaved by mild hydrogenolysis giving the sY peptides in good yield.

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Self‐Assembly of Fivefold‐Symmetric Molecules on a Threefold‐Symmetric Surface
Authors: Guillermet Olivier , Niemi Eeva , Nagarajan Samuthira , Bouju Xavier , Martrou David , Gourdon André , Gauthier Sébastien
Published: February 2009

Buckybowls: The adsorption of penta‐tert‐butylcorannulene, a molecule with fivefold symmetry, on Cu(111), a surface with threefold symmetry, is investigated by scanning tunneling microscopy complemented by structure calculations. The symmetry mismatch is resolved by the formation of threefold‐symmetric subunits consisting of three molecules, which combine with single molecules to form a nearly perfect filling of the plane (see picture).

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Electrochemical Gene‐Function Analysis for Single Cells with Addressable Microelectrode/Microwell Arrays
Authors: Lin Zhenyu , Takahashi Yasufumi , Murata Tatsuya , Takeda Michiaki , Ino Kosuke , Shiku Hitoshi , Matsue Tomokazu
Published: February 2009

To each his own: An addressable electrochemical device consisting of orthogonally arranged rows and columns of electrodes has been constructed to monitor protein expression in genetically engineered cells at the single‐cell level. The response based on redox cycling reflected the different expression levels of the enzyme from individual HeLa cells transfected with a plasmid vector including secreted alkaline phosphatase.

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An exploration into the practices of library Web usability in ARL academic libraries
Authors: Chen Yu‐Hui , Germain Carol Anne , Yang Huahai
Published: February 2009

A survey of the 113 academic libraries of the Association of Research Libraries (ARL) was administered to investigate whether Web usability Policies/Standards/Guidelines (PSGs) are in place, the levels of difficulty surrounding implementation, the impact of PSGs on actual usability practice, e.g., testing, resources, etc., and the relationship between ARL ranking and usability practice or PSGs. The response rate was over 74%. Results show that 25 (30%) libraries have PSGs dedicated to Web usability. Seventy‐one (85%) libraries have conducted usability testing on their main Web sites, online public access catalogs (OPAC), or lower‐level pages. Nevertheless, only seven libraries performed iterative testing of these platforms at pre‐, during, and post‐design stages. Statistical analysis indicates that having PSGs does not affect the amount of usability testing performed or the resources available for library Web usability initiatives. In addition, ARL ranking has no or little impact on PSGs, testing, or resources.
Hybrider statischer Nachweis für einen Stahlbeton‐Großsilo – Bausubstanzerhaltung versus Abriss und Neubau
Authors: Arnold Andreas , Kapphahn Gerd , Riepe Nicolai , Steffens Klaus
Published: February 2009

Dem Betreiber eines Gebäudes oder einer baulichen Anlage obliegt die verantwortliche Wahrnehmung der Verkehrssicherungspflicht. Er muss Vorkehrungen gegen voraussehbare Gefahrenquellen treffen. Die Verpflichtung umschließt sowohl den eigenen Betrieb als auch die Umwelt. Der hier geschilderte Fall einer vorsorgenden Klärung der Tragsicherheit von vorgeschädigten Flüssigkeitssilos ist bemerkenswert wegen seiner Komplexität, des eingeschlagenen Lösungsweges und des Ergebnisses (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ermittlung des Aufbaus und der Stoffkennwerte von Außenbauteilen mit Hilfe von In‐situ‐Messungen und FEM‐Berechnungen
Authors: Beißner Eckhard , Eilering Siegfried
Published: February 2009

Die international und national formulierten Ziele zum Klimaschutz können nur unter Einbeziehung des energieeffizienten Bauens und Sanierens des Gebäudebestandes erreicht werden. Kenntnisse über den konstruktiven Aufbau und der Stoffkennwerte der wärmeübertragenden Außenbauteile sind Voraussetzungen für die energetische Bilanzierung von Gebäuden. Die dazu erforderlichen Angaben können, insbesondere bei älteren Bauwerken, den Bauunterlagen häufig nicht mehr entnommen werden, da sie nicht mehr auffindbar oder unvollständig sind. Am Beispiel einer ein‐ und zweischaligen Außenwandkonstruktion wird gezeigt, dass die thermophysikalischen Eigenschaften mit Hilfe von In‐situ‐Messverfahren, kombiniert mit Simulationsrechnungen nach der Finite‐Elemente‐Methode, zerstörungsfrei ermittelt werden können (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamische Steifigkeit und Dämpfung von Pfahlgruppen
Authors: Sadegh‐Azar Hamid , Balthaus Hansgeorg , Hartmann Hans‐Georg
Published: February 2009

In diesem Beitrag werden die dynamische Steifigkeit und Dämpfung von Pfahlgruppen und ihre Auswirkung auf die Auslegung und Wirtschaftlichkeit der Pfahlgründung selbst und der Bauwerke darauf untersucht. Die Berechungen werden mit der sogenannten “Thin‐Layer‐Method”, einer sehr leistungsfähigen Berechnungsmethode im Frequenzbereich, durchgeführt (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative assessment of dielectric parameters for membrane lipid bi‐layers from RF permittivity measurements
Authors: Merla Caterina , Liberti Micaela , Apollonio Francesca , d'Inzeo Guglielmo
Published: February 2009

In this article, we propose and validate theoretical and experimental methods to quantitatively assess the Debye dielectric model of membrane lipid bi‐layers. This consists of two steps: permittivity measurements of biological solutions (liposomes), and estimation of the model parameters by inverse application of the Effective Medium Theory. The measurements are conducted in the frequency domain between 100 MHz and 2 GHz using a modified coaxial connector, at the temperatures of 27 and 30 °C. Estimations have been performed using a three‐layered model based on the Maxwell–Wagner formulation. Debye parameters (mean value ± standard error) found from fitting experimental data are:εs = 11.69 ± 0.09,ε∞ = 4.00 ± 0.07,frelax = 179.85 ± 6.20 MHz andεs = (1.1 ± 0.1) × 10−7S/m. This model can be used in microdosimetric studies aiming to precisely determine the E‐field distribution in a biological target down to the single cell level. In this context the use of an accurate membrane dielectric model, valid through a wide frequency range, is particularly appropriate. Bioelectromagnetics 30:286–298, 2009. © 2009 Wiley‐Liss, Inc.
Zeitabhängiges Verhalten von Makrokunststofffaserbeton und dessen Einfluss auf die Bemessung von Industriefußböden
Authors: Gossla Ulrich , Rieder Klaus‐Alexander
Published: February 2009

In diesem Beitrag werden Material‐ und Bauteilversuche an Makrokunststofffaserbeton vorgestellt. Die experimentellen Untersuchungen umfassen das Trag‐ und Verformungsverhalten unter Kurzzeit‐ und Langzeitbeanspruchung.

Anhand von Biegezugversuchen unter Dauerlast wird ein kritisches Belastungsniveau bestimmt, oberhalb dessen mit einem Kriechversagen zu rechnen ist. Unter Gebrauchslastniveau werden Kriechbeiwerte über einen Zeitraum von bis zu drei Jahren ermittelt.

Vergleichende Untersuchungen an elastisch gebetteten Platten unter mittiger Einzellast wurden durchgeführt. Zwei Platten waren aus Makrokunststofffaserbeton und zwei aus Stahlbeton. Daran wurden Kurzzeitbelastungen sowie Langzeitbelastungen über einen Zeitraum von 18 Monaten durchgeführt.

Das Hauptanwendungsgebiet von Makrokunststofffaserbeton ist die Bodenplatte. Die Bemessung erfolgt entweder als elastisch gebettete Platte nach der Elastizitätstheorie oder im gerissenen Zustand unter Berücksichtigung der Faserwirkung. Aufbauend auf den vorgestellten Untersuchungen werden Vorschläge zur Bemessung im gerissenen Zustand unter Berücksichtigung von ständig wirkenden Lasten vorgestellt.
Influence of naturally‐occurring 5′‐pyrophosphate‐linked substituents on the binding of adenylic inhibitors to ribonuclease a: An X‐ray crystallographic study
Authors: Holloway Daniel E. , Chavali Gayatri B. , Leonidas Demetres D. , Baker Matthew D. , Acharya K. Ravi
Published: February 2009

Ribonuclease A is the archetype of a functionally diverse superfamily of vertebrate‐specific ribonucleases. Inhibitors of its action have potential use in the elucidation of the in vivo roles of these enzymes and in the treatment of pathologies associated therewith. Derivatives of adenosine 5′‐pyrophosphate are the most potent nucleotide‐based inhibitors known. Here, we use X‐ray crystallography to visualize the binding of four naturally‐occurring derivatives that contain 5′‐pyrophosphate‐linked extensions. 5′‐ATP binds with the adenine occupying the B2 subsite in the manner of an RNA substrate but with the γ‐phosphate at the P1 subsite. Diadenosine triphosphate (Ap3A) binds with the adenine in syn conformation, the β‐phosphate as the principal P1 subsite ligand and without order beyond the γ‐phosphate. NADPH and NADP+ bind with the adenine stacked against an alternative rotamer of His119, the 2′‐phosphate at the P1 subsite, and without order beyond the 5′‐α‐phosphate. We also present the structure of the complex formed with pyrophosphate ion. The structural data enable existing kinetic data on the binding of these compounds to a variety of ribonucleases to be rationalized and suggest that as the complexity of the 5′‐linked extension increases, the need to avoid unfavorable contacts places limitations on the number of possible binding modes. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 995–1008, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Optimization of elastin‐like polypeptide fusions for expression and purification of recombinant proteins in plants
Authors: Conley Andrew J. , Joensuu Jussi J. , Jevnikar Anthony M. , Menassa Rima , Brandle Jim E.
Published: February 2009

The demand for recombinant proteins for medical and industrial use is expanding rapidly and plants are now recognized as an efficient, inexpensive means of production. Although the accumulation of recombinant proteins in transgenic plants can be low, we have previously demonstrated that fusions with an elastin‐like polypeptide (ELP) tag can significantly enhance the production yield of a range of different recombinant proteins in plant leaves. ELPs are biopolymers with a repeating pentapeptide sequence (VGVPG)n that are valuable for bioseparation, acting as thermally responsive tags for the non‐chromatographic purification of recombinant proteins. To determine the optimal ELP size for the accumulation of recombinant proteins and their subsequent purification, various ELP tags were fused to green fluorescent protein, interleukin‐10, erythropoietin and a single chain antibody fragment and then transiently expressed in tobacco leaves. Our results indicated that ELP tags with 30 pentapeptide repeats provided the best compromise between the positive effects of small ELP tags (n = 5–40) on recombinant protein accumulation and the beneficial effects of larger ELP tags (n = 80–160) on recombinant protein recovery during inverse transition cycling (ITC) purification. In addition, the C‐terminal orientation of ELP fusion tags produced higher levels of target proteins, relative to N‐terminal ELP fusions. Importantly, the ELP tags had no adverse effect on the receptor binding affinity of erythropoietin, demonstrating the inert nature of these tags. The use of ELP fusion tags provides an approach for enhancing the production of recombinant proteins in plants, while simultaneously assisting in their purification. Biotechnol. Bioeng. 2009;103: 562–573. © 2009 Wiley Periodicals, Inc.
Parameters Influencing the Release of Tertiary Alcohols from the Surface of “Spherical” Dendrimers and “Linear” Stylomers by Neighbouring‐Group‐Assisted Hydrolysis of 2‐Carbamoylbenzoates
Authors: Trachsel Alain , de Saint Laumer Jean‐Yves , Haefliger Olivier P. , Herrmann Andreas
Published: February 2009

Size is not all! Investigation of the controlled release of tertiary alcohols from the surface of dendrimers and “stylomers” as polymer model systems (see scheme) showed that the polarity of the conjugates and structural modifications in close proximity to the release unit have a stronger influence on the rates of hydrolysis than the size (generation) or shape (linear or spherical) of the macromolecules.

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The influence of structural and physico‐chemical parameters on the release of a volatile tertiary alcohol (2‐methyl‐1‐phenyl‐2‐propanol) by neighbouring‐group‐assisted cyclisation of 2‐carbamoylbenzoates at neutral pH was investigated by comparing the covalent‐bond cleavage from the surface of linear, comblike poly(propylene imine) “stylomers” and their corresponding spherical, globular dendrimers. Determination of the kinetic rate constants for the stepwise intramolecular cyclisation of the 2‐carbamoylbenzoate moiety by using HPLC showed that the polarity of the conjugates, and thus their solubility in the aqueous reaction medium, has a stronger influence on the rates of hydrolysis than the size (generation) or shape (linear or spherical) of the macromolecules. Furthermore, structural modifications in close proximity to the release unit, such as the presence of functionalities with catalytic activity, have a strong impact on the release efficiency of the active molecules. An understanding of the physico‐chemical parameters determining the local environment of the covalent‐bond cleavage site is therefore an important prerequisite to transfer the characteristics of small molecules to larger structures such as oligomers and polymers and thus to design efficient macromolecular conjugates for the controlled delivery of bioactive compounds.
The Quest for Ring Opening of Oxaphosphirane Complexes: A Coupled‐Cluster and Density Functional Study of CH3PO Isomers and Their Cr(CO)5 Complexes
Authors: Krahe Oliver , Neese Frank , Streubel Rainer
Published: February 2009

Opening gambit: A high‐level theoretical study on the relative stabilities of oxaphosphirane isomers and their Cr(CO)5 complexes is reported (see picture). Furthermore, thermodynamics and kinetics of possible ring‐opening reactions of these complexes in the presence of a {Cp2TiIIICl} fragment are theoretically investigated. The CO bond cleavage is predicted to be the most efficient pathway, thus leading to reactive intermediates that are attractive for synthetic applications.

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A high‐level theoretical study on the relative stabilities of oxaphosphirane isomers and their Cr(CO)5 complexes is reported. Furthermore, thermodynamics and kinetics of possible ring‐opening reactions of these complexes in the presence of a {Cp2TiIIICl} fragment are theoretically investigated. The CO bond cleavage is predicted to be the most efficient pathway thus leading to reactive intermediates that are attractive for synthetic applications. The ring‐opening reaction is predicted to not lead to the most favorable product (a coordinated phosphinidene oxide species). Rather, the ring‐opening product is separated by a substantial barrier of about 24 kcal mol−1 from the thermodynamically most favorable species.
Two‐Dimensional Oligo(phenylene‐ethynylene‐butadiynylene)s: All‐Covalent Nanoscale Spoked Wheels
Authors: Lei Shengbin , Ver Heyen An , De Feyter Steven , Surin Mathieu , Lazzaroni Roberto , Rosenfeldt Sabine , Ballauff Matthias , Lindner Peter , Mössinger Dennis , Höger Sigurd
Published: February 2009

Round and round: Covalently bound spokes induce an efficient template‐directed cyclization towards a rigid molecular wheel (see figure) and afford dramatically increased shape‐persistence properties compared with non‐strutted macrocycles.

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The synthesis and characterization of a shape‐persistent two‐dimensional (2D) organic compound is described in detail. In a rational modular synthesis of a dodecaacetylene precursor and its subsequent template‐aided cyclization, we obtained a molecularly defined, stable, C6‐symmetric, rigid, spoked wheel. Peripheral tert‐butyl groups and alkyl chains attached to the plane of the molecule provide sufficient solubility, so that the 2D oligomer can be fully characterized by MALDI‐MS, GPC, and 1H NMR, UV/Vis absorption, and fluorescence spectroscopy. Molecular mechanics and dynamics simulations indicate that the most stable conformer of the molecule in vacuum is a shallow boat conformation with a small dihedral angle. Comparisons with the precursor as well as a ring‐only structure clearly reveal the high rigidity of the title compound. Small‐angle neutron scattering (SANS) experiments in [D8]THF and CDCl3 affirm the rigid backbone structure in solution, that is, a radius of about 2.7 nm and a thickness of about 0.22 nm. STM investigations illustrate that the wheel molecules adsorb with their molecular plane parallel to the surface and can form hexagonal crystalline domains (unit cell parameters are a=b=6.0±0.2 nm and θ=60±2°), with the tert‐butyl groups on the apexes staggered. Such staggering induces chirality in the organized domains. AFM investigations demonstrate that the wheel molecules inside overlayers organize in the same way as in the layer directly in contact with the surface. This indicates an epitaxial growth characteristic of the film.
New Polyalkynyl Dendrons and Dendrimers: “Click” Chemistry with Azidomethylferrocene and Specific Anion and Cation Electrochemical Sensing Properties of the 1,2,3‐Triazole‐Containing Dendrimers
Authors: Camponovo Jérémy , Ruiz Jaime , Cloutet Eric , Astruc Didier
Published: February 2009

Dendrimers for ion sensing: The synthesis and use of new tris‐alkynyl dendrons are reported. So‐called “click” reactions of the dendrimers described with azidomethylferrocene give 27‐ferrocenyl, 81‐ferrocenyl, and 243‐ferrocenyl dendrimers. Electrochemical recognition of oxo‐anions and Pd2+ cations has been compared using the three polyferrocenyl dendrimers.

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The synthesis and use of the new tris‐alkynyl dendrons 2 to 5 are reported, including the Williamson reaction of 5 with 9‐iodo (9), 27‐iodo (11), and 81‐iodo (12) dendritic cores to yield 27‐alkynyl (13), 81‐alkynyl (14), and 243‐alkynyl (15) dendrimers. So‐called “click” reactions of these three dendrimers with azidomethylferrocene (20) give 27‐ferrocenyl (16), 81‐ferrocenyl (17), and 243‐ferrocenyl (18) dendrimers. Electrochemical recognition of oxo‐anions (H2PO4− and ATP2−) and Pd2+ cation has been compared using the three polyferrocenyl dendrimers. Derivatization of Pt electrodes with the dendrimers for recognition becomes more facile with increasing size of the dendrimer. This first “click” dendrimer bearing 243‐ferrocenyl groups is the best one in the series to obtain robust, recyclable modified Pt electrodes, whereas previous “click” ferrocenyl dendrimers have not been suitable for this purpose.
Palladium‐Catalyzed Cyclopropanation of Alkenyl Silanes by Diazoalkanes: Evidence for a Pd0 Mechanism
Authors: Berthon‐Gelloz Guillaume , Marchant Mélanie , Straub Bernd F. , Marko Istvan E.
Published: February 2009

Pd0 does the trick! Alkenyl silanes are efficiently cyclopropanated by diazoalkanes at low Pd loadings (see scheme). Clear evidence for the involvement of a Pd0 resting state for this reaction is given.

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Alkenyl silanes are efficiently converted to the corresponding silyl cyclopropanes in the presence of a slight excess of diazomethane (2–4 equiv) and a low loading of Pd(OAc)2 (<0.5 mol %). Diazoethane and diazobutane can also be employed and yield silyl cyclopropanes with diastereoselectivities of up to 10:1 for the trans isomer. When conducted on a 4 g scale, the reaction only required a catalyst loading of 5×10−3 mol %, which corresponds to a turnover frequency of 40 000 h−1. Competition experiments revealed that vinyl silanes can be selectively cyclopropanated in the presence of an aliphatic terminal alkene and styrene. The complex [Pd02(DVTMS)3] (38, DVTMS=divinyltetramethyldisiloxane) proved to be an exceptionally active catalyst for the cyclopropanation reaction, giving complete conversion at −35 °C in 1 min. Intermolecular and intramolecular competition experiments with DVTMS (36), both with Pd(OAc)2 and 38, provided strong evidence for a Pd0(alkenyl silane)3 resting state. Detailed density functional calculations on the reaction pathways for the cyclopropanation of trimethylvinylsilane and DVTMS by diazomethane with Pd0 corroborated the experimental observations.
Enantioselective Total Synthesis of (−)‐Candelalides A, B and C: Potential Kv1.3 Blocking Immunosuppressive Agents
Authors: Oguchi Takamasa , Watanabe Kazuhiro , Ohkubo Kôichi , Abe Hideki , Katoh Tadashi
Published: February 2009

Potential immunosuppressive agents: Candelalides A, B and C (see figure), novel blockers of the voltage‐gated potassium channel Kv1.3, have been efficiently synthesized for the first time in a convergent and unified manner starting from (+)‐5‐methyl‐Wieland–Miescher ketone. The method explored has potential for preparing various types of candelalide analogues for the structure–activity relationship studies.

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Novel Kv1.3 blocking immunosuppressants, (−)‐candelalides A, B and C, were efficiently synthesized for the first time in a convergent and unified manner starting from (+)‐5‐methyl‐Wieland–Miescher ketone. The synthetic method involved the following key steps: i) a strategic [2,3]‐Wittig rearrangement of a stannylmethyl ether to install the stereogenic center at C9 and the exo‐methylene function at C8 present in the decalin portion; ii) a straightforward coupling of a trans‐decalin portion (BC ring) and a γ‐pyrone moiety through the C16C3′ bond to assemble the requisite carbon framework; and iii) a construction of a characteristic di or tetrahydropyran ring (A ring) by internal nucleophilic ring closure of a hydroxy aldehyde or a hydroxy epoxide. The present total synthesis has fully established the absolute configuration of these natural products.
Optical Response Sensitive to the Assembly in a Molecular Material: Ultrathin Film with a Vanishing Electronic Absorption
Authors: Rajesh K. , Radhakrishnan T. P.
Published: February 2009

The characteristic electronic absorption of a zwitterionic molecule arising from an intramolecular charge‐transfer transition observed in the solution and the bulk solid states vanishes completely when the molecules are assembled into mono‐ and multilayer Langmuir–Blodgett films (see figure). Microscopy and spectroscopy investigations and computational modeling provide insight into this remarkable phenomenon.

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Optical properties of single‐component molecular materials can often be described in terms of modest perturbations on the responses of the molecular building blocks; in specific systems, the modifications may be more pronounced. In all cases, however, the effects are broadly independent of the form of assembly, such as thin films, nanostructures and crystals, even though variations may exist at the quantitative level. We present a very different situation encountered with an amphiphilic molecule possessing a strongly polar head group that shows similar electronic absorption spectra in the solution as well as the bulk solid state, but a dramatically different one in ultrathin Langmuir–Blodgett (LB) films. The lowest energy absorption is switched off completely in the latter. It is demonstrated further that a metastable form of the LB film exhibiting the normal molecular spectrum can be generated, although its lowest energy absorption decays and vanishes over a period of time. The Langmuir films formed at the air/water interface and the corresponding LB films are examined through pressure–area isotherms, microscopy and spectroscopy. The experimental observations coupled with models constructed through computational investigations allowed us to interpret the unusual optical responses, which are a result of the specific supramolecular 2D assembly in the LB film and the impact of the neighboring molecular dipoles on the intramolecular charge transfer transition. The present study illustrates that selective molecular design and directed assembly can be exploited to elicit dramatic changes in physical responses of molecular materials and realize novel effects in molecular nanostructures.
Solid‐State Enantiopure Organic Nanocubes Formed by Self Organization of a C3‐Symmetrical Tribenzotriquinacene
Authors: Strübe Jörg , Neumann Beate , Stammler Hans‐Georg , Kuck Dietmar
Published: February 2009

Cubic aggregation: The racemic C3‐symmetrical tribenzotriquinacene 1 was synthesized and found to crystallize in cubic aggregates consisting of eight homochiral molecules. The major driving force for this unique supramolecular aggregation may be attributed to the 24 equivalent sub‐van der Waals interactions between the bromine atoms located at the convex surface of the triquinacene cores, rather than to polar interactions between the nitrobenzene units within and between the nanocubes.

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Photo‐Induced Spin Transition of Iron(III) Compounds with π–π Intermolecular Interactions
Authors: Hayami Shinya , Hiki Kenji , Kawahara Takayoshi , Maeda Yonezo , Urakami Daisuke , Inoue Katsuya , Ohama Mitsuo , Kawata Satoshi , Sato Osamu
Published: February 2009

Photo‐switching: The LIESST effect could be observed by introducing π–π intermolecular interaction even for iron(III) spin‐crossover (SCO) compounds being the relatively small ΔrHL. Introduction of strong intermolecular interactions can be widely used in the design of a variety of optically switchable molecules (see figure).

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Iron(III) spin‐crossover compounds [Fe(pap)2]ClO4 (1), [Fe(pap)2]BF4 (2), [Fe(pap)2]PF6 (3), [Fe(qsal)2]NCS (4), and [Fe(qsal)2]NCSe (5) (Hpap=2‐(2‐pyridylmethyleneamino)phenol and Hqsal=2‐[(8‐quinolinylimino)methyl]phenol) were prepared and their spin‐transition properties investigated by magnetic susceptibility and Mössbauer spectroscopy measurements. The iron(III) compounds exhibited spin transition with thermal hysteresis. Single crystals of the iron(III) compounds were obtained as suitable solvent adducts for X‐ray analysis, and structures in high‐spin (HS) and low‐spin (LS) states were revealed. Light‐induced excited‐spin‐state trapping (LIESST) effects of the iron(III) compounds were induced by light irradiation at 532 nm for 1–3 and at 800 nm for 4 and 5. The activation energy Ea and the low‐temperature tunneling rate kHL(T→0) of iron(III) LIESST compound 1 were estimated to be 1079 cm−1 and 2.4×10−8 s−1, respectively, by HS→LS relaxation experiments. The Huang–Rhys factor S of 1 was also estimated to be 50, which was similar to that expected for iron(II) complexes. It is thought that the slow relaxation in iron(III) systems is achieved by the large structural distortion between HS and LS states. Introduction of strong intermolecular interactions, such as π–π stacking, can also play an important role in the relaxation behavior, because it can enhance the structural distortion of the LIESST complex.
Evaluation of hypertensive males for primary coronary heart disease events using conventional risk factors and maximal exercise testing
Authors: Hossack K. F. , Bruce R. A. , De ROUEN T. A.
Published: February 2009

Whereas hypertension is a risk factor for primary coronary heart disease events, the relative contributions of other risk factors and abnormal responses to symptom‐limited maximal exercise are not well‐established. After 5.2±1.5 years of follow‐up of 633 men with clinically‐diagnosed hypertension based upon criteria of examining physicians (whether or not the men were currently treated for hypertension), 54 primary events were revealed. The annual coronary heart disease (CHD) event rate of 16.9/1000 men at risk was significantly higher than the annual rate of 3.6/1000 found for healthy men (p<0.0001).

Variables associated with increased risk were smoking cigarettes, risk factor count or tally, chest pain during exercise, percentage of functional aerobic impairment, and percentage heart rate impairment, the latter two variables suggesting early evidence of left ventricular dysfunction on strenuous exertion. Ischemic ST depression was not an important predictor. The three exercise variables were included in an exercise predictor count, and multivariate analysis revealed that this count and the risk factor count were the most important predictors of primary CHD events. Combining the risk factor count and the exercise predictor count, three groups with increasing risk of primary CHD events were identified. In those persons with both a risk factor count and exercise predictor count of zero, the annual rate was 7.3 events/1000 man‐years; when either count was one or more, the rate was 15.5 events/1000 man‐years; when both counts were one or more, the rate was 49.5 events/1000 man‐years.
The distribution and severity of coronary artery disease and left ventricular dysfunction among patients with single coronary artery disease and angina pectoris
Authors: Vieweg W. V. R. , Warren S. E. , Alpert J. S. , Hagan A. D.
Published: February 2009

The distribution and severity of coronary artery disease and left ventricular dysfunction were evaluated in 103 patients with single coronary artery disease and angina pectoris. The coronary arterial patterns were separated into right (76), mixed (18), and left (9) systems depending upon the blood supply to the inferior surface of the left ventricle. The following relationships were noted:

(1) In patients with single coronary artery disease and angina pectoris, coronary arterial lesions are similar among right, mixed, and left systems.

(2) In order of frequency, single coronary artery disease occurred most commonly in the left anterior descending coronary artery (55), next most commonly in the right coronary artery (36), and least commonly in the circumflex/obtuse marginal coronary artery (12).

(3) Left ventricular wall motion abnormalities were seen in descending order of frequency: patients with right coronary artery (50%), left anterior descending coronary artery (36%), and circumflex/obtuse marginal coronary artery (25%) disease.
Coronary arterial and left ventriculographic findings in patients with double‐vessel disease and angina pectoris
Authors: Vieweg W. V. R. , Warren S. E. , Alpert J. S. , Hagan A. D.
Published: February 2009

The distribution and severity of coronary artery disease and left ventricular wall abnormalities are described in 119 patients with double‐vessel disease and angina pectoris. The coronary arterial patterns were divided into right (84), mixed (17), and left (18) systems, depending upon the blood supply to the inferior surface of the left ventricle. Patterns of double‐vessel disease were separated into those with 50% or greater reduction of luminal diameter involving the left anterior descending and circumflex/obtuse marginal arteries (2‐LC), circumflex/obtuse marginal and right coronary arteries (2‐CR), and left anterior descending and right coronary arteries (2‐LR). The following relationships were noted:

(1) Left anterior descending and right coronary artery disease occurs with twice the frequency of 2‐LC or 2‐CR disease, supporting the thesis that of the three major coronary arteries, the circumflex/obtuse marginal arteries contribute least to angina pectoris.

(2) The mid portion of the left anterior descending artery is most commonly involved and the left main coronary artery least commonly involved in patients with double‐vessel disease.

(3) Left ventricular wall motion abnormalities are found in one‐half of patients with double‐vessel disease and angina pectoris with hypokinesis usually found in all areas except at the apex where dyskinesis is usually seen.
Unusual echocardiographic appearances attributable to submitral calcification simulating left ventricular “masses”
Authors: D'CRUZ I. A. , Devaraj N. , Hirsch L. J. , Glick G.
Published: February 2009

Using M‐mode and cross‐sectional echocardiography, we visualized in five patients abnormal large echos attributable to anterior submitral calcification or sclerosis (on or near the ventricular aspect of the anterior mitral leaflet). Such abnormal echos on M‐mode echocardiography could have been mistaken for a mass in the left ventricular chamber. Autopsy in two cases confirmed the presence of nonrheumatic anterior submitral calcification. Echocardiographic features of anterior submitral calcification which are helpful in differentiating it from neoplastic or thrombotic ventricular masses include (1) less diastolic mobility and more echo density; (2) continuity with the base of the anterior mitral leaflet and/or the posterior aortic root region, whereas tumors or thrombi are attached to the left ventricular wall; and (3) calcification in the region of posterior “mitral annulus.” Cross‐sectional long‐axis views and M‐mode scanning from the left ventricle to the aortic root were particularly helpful in making the differentiation.
Salvage of acutely ischemic myocardium by emergency coronary artery bypass grafting
Authors: Muller J. E. , Antman E. , Green L. H. , Koster J. K.
Published: February 2009

After cardiac catheterization a 53‐year‐old patient developed widespread myocardial ischemia that produced electromechanical dissociation and cardiogenic shock. The administration of methylprednisolone, the initiation of cardiopulmonary bypass and hypothermia within 40 min of the onset of ischemia, and reperfusion within 90 min of the onset of ischemia were sufficient to salvage a major portion of the ischemic myocardium.
Late recovery in peripartum cardiomyopathy
Authors: Moreyra A. E. , Kostis J. B. , Amendo M.
Published: February 2009

Full recovery occurred after 15 months of severe congestive heart failure in a patient with peripartum cardiomyopathy. Clinical improvement was noted when propranolol was added to conventional therapy.
Evidence for transient limitations in coronary blood flow during unstable angina pectoris: hemodynamic changes with spontaneous pain at rest versus exercise‐induced ischemia following stabilization of angina
Authors: Smitherman T. C. , Hillert M. C. , Narahara K. A. , Burden L. L. , Lipscomb K. M. , Shapiro W. , Nixon J. V.
Published: February 2009

The pathophysiologic basis for the deterioration of patients with stable angina pectoris to unstable angina is unclear. Central to this issue is the question of whether myocardial ischemia occurs at the same or at a lower myocardial oxygen demand during unstable periods as during stable periods. Consequently, we compared myocardial oxygen demand in 12 patients at the onset of spontaneous pain during unstable angina to myocardial oxygen demand during exercise‐induced ischemia after resumption of stable angina, 6–12 weeks later. Myocardial oxygen demand was estimated from values for heart rate (HR), systolic blood pressure (BP), and the rate‐pressure product (RPP). Rate‐pressure product is the heart rate × systolic blood pressure × 10‐2 (mmHg/min/102). There was definite evidence for coronary artery spasm for only one patient. There was no difference in heart rate, blood pressure, or rate‐pressure product during pain‐free intervals in the hospital and just before the start of exercise testing. Mean H R (71.2± 11.1 beats/min; mean ± standard deviation) and RPP (95.8±20.0 mmHg/min/102) just before spontaneous angina during the unstable period were significantly lower (p<0.001) than at the termination of bicycle ergometry in both the supine (HR, 96.9±10.5 beats/min; RPP, 141.8±25.0 mmHg/min/102) and upright (HR, 98.1±13.6 beats/min; RPP, 143.0±32.2 mmHg/min/102) positions. Blood pressure (134.5 ± 17.6 mmHg) just before spontaneous angina was significantly lower than at the conclusion of both supine (145.6±13.3 mmHg) and upright (145.1 ±18.6 mmHg) ergometry. The observation that myocardial oxygen demand was lower at the threshold of ischemia with spontaneous angina than with exercise‐induced ischemia is consistent with the hypothesis that there were transient, reversible limitations in coronary blood flow during the period of unstable angina. There was also a moderate but significant rise in estimated myocardial oxygen demand just before spontaneous angina in these patients, but the nature of the data do not allow us to distinguish whether or not this rise was part of the cause or an effect of ischemia. While the results of this study did not identify the cause for the transient limitations in coronary flow, coronary artery spasm without ST‐segment elevation, intracoronary platelet aggregates, and hemorrhage into atherosclerotic plaques are possibilities that are consistent with these hemodynamic observations.
Sympathetic nervous system activity during sodium restriction in essential hypertension
Authors: Warren S. E. , Vieweg W. V. R. , O'Connor D. T.
Published: February 2009

Sympathetic nervous system activity was studied in 38 patients with essential hypertension during high‐ and low‐sodium diets. Salt restriction was associated with a modest (6 mmHg) decline in mean arterial pressure, while the urinary excretion of catecholamines, metanephrines, and vanillylmandelic acid increased significantly. Plasma renin activity also increased, it is concluded that short‐term low‐sodium diet therapy for essential hypertension results in only small decrements in mean arterial pressure and may be limited in hypotensive effect by activation of the sympathetic nervous system. Support is offered for the rationale of sympatholytic drug therapy as an initial step in the management of hypertensive patients requiring arterial pressure reductions greater than those afforded by diet alone.
Total occlusion of the left main coronary artery: clinical and catheterization findings
Authors: Trnka K. E. , Febres‐ROMAN P. R. , Cadigan R. A. , Crone R. A. , Williams T. H.
Published: February 2009

In this report clinical and angiographic data on three patients with total occlusion of the left main coronary artery is presented. Two of our cases demonstrated rich collateralization with good preservation of left ventricular (LV) function. The third case, with initial subtotal occlusion and no collaterals, sustained a severe anterolateral myocardial infarction (MI) responding to the use of the intra‐aortic balloon pump (IABP).

This report is consistent with the findings of others who suggest the possible beneficial effect of collaterals in preserving myocardial contractility in this unusual situation. We suggest that the IABP may be of benefit in patients with total occlusion of the left main coronary artery and sparse collaterals who remain unstable and cannot be operated on immediately.
Observations on exercise testing and coronary arteriography
Authors: Balcon R. , Cattell M. R. , Feurelicht J.
Published: February 2009

Exercise tests were performed on 551 patients with a clinical diagnosis of coronary artery disease during their admission for angiography. A computer‐generated index (CI, 0–100%) was used to describe the coronary anatomy, and additional data on left ventricular contraction abnormalities were recorded. Significant correlations exist between exercise performance and angina grade, coronary pathology, left ventricular function, and prognosis.
Antiarrhythmic effect of the calcium antagonist tiapamil (ro 11–1781) by intravenous administration in patients with coronary heart disease
Authors: Nowak F. G. , Cocco G. , Chu D. , Gasser D. F.
Published: February 2009

Twenty coronary patients with a median age of 76 years were treated in the coronary care unit with tiapamil, a new Ca2+ antagonist, by intravenous infusion (until December, 1979, the generic name was dimeditiapramine). The following arrhythmias were identified: atrial fibrillation with ventricular rate >95 beats/min (5 patients); supraventricular premature complexes (SVPC) (4 patients); and ventricular premature complexes (VPC), Lown grades 2–4 (15 patients). Electrocardiograms and hemodynamic parameters were continuously monitored prior to, during, and after the therapy. In patients with atrial fibrillation, sinus rhythm was not restored, but tiapamil decreased the ventricular rate by 54%.

In patients with VPC, the median frequency of VPC decreased from 310.5 before tiapamil to 32.5 beats/h at the fourth hour of therapy (p<0.01). The median ectopic/sinus beat ratio decreased from 0.083 (pretreatment) to 0.008 at the fourth hour of infusion (p<0.10). In one of the patients with an insufficient decrease in the number of VPC, the VPC changed from class 4a (pretreatment) to class 2 (during the therapy), returning to class 4a after the infusion was stopped.

Tiapamil reduced the median systolic and diastolic blood pressures by 8.3 and 7.1%, respectively (p<0.05), the third hour. Hypotension and bradycardia were observed in 5/20 patients. The results show that tiapamil is effective against both supraventricular and ventricular arrhythmias, and thus its spectrum of action differs from that of other calcium antagonists.
Left ventricular volume and ejection fraction determination by cross‐sectional echocardiography in patients with coronary artery disease: A prospective study
Authors: Erbel R. , Schweizer P. , Meyer J. , Grenner H. , Krebs W. , Effert S.
Published: February 2009

In a prospective study the accuracy of cross‐sectional echocardiography for determination of left ventricular (LV) volume and ejection fraction (EF) was analyzed in 53 patients with coronary artery disease and compared to that of cineangiocardiography (angio). From the apex of the heart phased‐array wide‐angle (84°) electronic echocardiograms were received in the RAO‐equivalent view. Angios were obtained in a 30° RAO view. Using Simpson's rule, end‐diastolic (EDV) and end‐systolic (ESV) LV volumes were calculated, and the EF derived. Left ventricular long axis was transected in eight segments, yielding seven diameters. In 50 of the 53 patients cross‐sectional echocardiograms could be recorded. The correlation between cineangiocardiography and cross‐sectional echocardiography for EDV was highly significant: r = 0.936, y = 0.667x + 27.1, standard error of estimate (syx) ± 22.2 ml; for ESV: r = 0.970, y = 0.699x + 14.7, syx ± 14.5 ml; for stroke volume: r = 0.721, y = 0.503x + 11.3, syx ± 15.3 ml; for EF: r = 0.909, y = 0.740x + 11.3, syx ±6.0%. Angio mean long axis was 10.2± 1.2 cm, cross‐sectional echocardiographic long axis 8.7 ± 1.3 cm. Mean LV diameter determined by cineangiocardiography was longer than when determined by cross‐sectional echocardiography. The mean difference reached 2.0 cm in the middle of the LV. Our prospective comparative study revealed that LV volumes and EF were underestimated by cross‐sectional echocardiography compared to cineangiocardiography because of a methodological systematic error caused by a tangential cut of the heart. In the RAO‐equivalent view the “true” long axis was missed. The high correlation coefficients, however, indicate that the “true” LV volume and EF can be calculated from the given regression equations. Serial measurements should be legitimated.
Heart rate responses in patients with sinus node disease compared to controls: Physiological implications and diagnostic possibilities
Authors: Vallin H. O. , Edhag K. O.
Published: February 2009

The autonomic regulation of heart rate was examined in 30 patients with symptoms of sinus node disease (SND) and 18 control subjects. Heart rate, expressed as sinus cycle length, was determined after injection of isoprenaline (0.1 μg/kg), propranolol (0.1 mg/kg), and atropine (0.02 mg/kg); heart rate was also determined at maximal exercise and during carotid sinus stimulation. In addition, heart rate responses, expressed as the absolute change in sinus cycle length, were calculated.

Mean heart rates after the applied maneuvers were all significantly different in the patient group, but so was the mean spontaneous heart rate. None of the induced changes differed significantly between the groups. Thus, although all these patients had impaired sinus node automaticity no uniform decrease in responsiveness to adrenergic or cholinergic stimulation or to inhibition of autonomic influences could be detected. The response patterns were heterogeneous, indicating diversity of the underlying mechanisms.

No single heart rate reaction provided a satisfying diagnostic capacity for SND. However, the combined sensitivity of the three tests—isoprenaline stimulation, carotid sinus pressure, and autonomic inhibition—was 97% with a specificity of 50%. Clinically, normal findings in all these three tests, i.e., with resulting heart rates greater than 100, 55, and 70 beats/min, respectively, strongly suggest absence of SND.