Resource
2010 EN
Kevin R. Covey · Peter Plavchan · Fabienne Bastien
+6 more
Variability is a defining characteristic of young stellar systems, andoptical variability has been heavily studied to select and characterize thephotospheric properties of young stars. In recent years, multi-epochobservations sampling a wider range of wavelengths and time-scales haverevealed a wealth of time-variable phenomena at work during the star formationprocess. This splinter session was convened to summarize recent progress inproviding improved coverage and understanding of time-variable processes inyoung stars and circumstellar disks. We begin by summarizing results fromseveral multi-epoch Spitzer campaigns, which have demonstrated that many youngstellar objects evidence significant mid-IR variability. While some of thesevariations can be attributed to processes in the stellar photosphere, othersappear to trace short time-scale changes in the circumstellar disk which can besuccessfully modeled with axisymmetric or non-axisymmetric structures. We alsoreview recent studies probing variability at shorter wavelengths that provideevidence for high frequency pulsations associated with accretion outbursts,correlated optical/X-ray variability in Classical T Tauri stars, and magneticreversals in young solar analogs.
Resource
2009 EN
Ivana Bochicchio · Mariafelicia De Laurentis · Ettore Laserra
In this paper we investigate the gravitational waves emission by stellardynamical structures as complex systems in the quadrupole approximationconsidering bounded and unbounded orbits. Precisely, after deriving analyticalexpressions for the gravitational wave luminosity, the total energy output andgravitational radiation amplitude, we present a computational approach toevaluate the gravitational wave-forms from elliptical, circular, parabolic andhyperbolic orbits as a function of Keplerian parameters.
Journals
2009 EN
Piccione Maria · Piro Ettore · Pomponi Maria Grazia
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Costello syndrome is caused by mutations in the HRAS proto‐oncogene whose clinical features in the first year of life include fetal and neonatal macrosomia with subsequent growth impairment due to severe feeding difficulties. We report on a premature male with Costello syndrome due to a rare G13C HRAS mutation and describe his clinical features and evolution during the first year of life. The diagnosis of Costello syndrome may be difficult at birth, especially in very preterm infants in whom feeding difficulties, reduced subcutaneous adipose tissue and failure to thrive are also part of their typical presentation. © 2009 Wiley‐Liss, Inc.
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Journals
2009 DE
Heckmann Dominik · Laufer Burkhardt · Marinelli Luciana
+5 more
Substitution einer Carboxygruppe : Alle Integrinrezeptoren binden ihre Liganden, die einen Aspartatrest enthalten, in der Metallionen‐abhängigen Adhäsionsstelle (MIDAS). Bislang waren alle Versuche, die Carboxygruppe durch andere isostere Gruppen mit verbesserten pharmakologischen Eigenschaften zu ersetzen, gescheitert. Nun wurde gezeigt, dass die Carboxygruppe unter Beibehaltung der hohen Bindungsaktivität durch eine Hydroxamsäureeinheit ersetzt werden kann (Bild: Ligand in der Bindungstasche von αvβ3).
Journals
2009 DE
Heckmann Dominik · Laufer Burkhardt · Marinelli Luciana
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Die Bindung der Carboxygruppe eines Aspartatrestes an die Metallionen‐abhängige Adhäsionsstelle (MIDAS) ist ein Schlüsselelement der Ligandenbindung an Integrine. Dies wurde durch die Bindung des cyclischen Pentapeptids cyclo (RGDf N MeV) (Cilengitid) an das Integrin αvβ3 demonstriert (siehe Bild). H. Kessler und Mitarbeiter zeigen in der Zuschrift auf S. 4501 ff. , dass sich die Carboxygruppe, die bisher für unverzichtbar gehalten wurde, durch eine Hydroxamsäureeinheit ersetzen lässt.
Journals
2009 EN
Heckmann Dominik · Laufer Burkhardt · Marinelli Luciana
+5 more
A suitable substitute : All integrin receptors bind their ligands, which contain an aspartate residue, in the metal‐ion‐ dependent adhesion site (MIDAS). So far all attempts to replace the carboxyl group of aspartate with other, pharmacologically favorable isosteric groups have failed. Now it has been shown that a hydroxamic acid group can replace the carboxyl group; the resulting ligand retains its high binding activity. The picture shows one such ligand in the binding site of αvβ3.
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2009 EN
Heckmann Dominik · Laufer Burkhardt · Marinelli Luciana
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The binding of the carboxyl group of an aspartate residue in the metal‐ion‐dependent adhesion site (MIDAS) is a key feature in the binding of ligands to integrins. This finding was demonstrated by the binding of the cyclic pentapeptide cyclo (RGDf N MeV) (Cilengitid) to the integrin αvβ3 (see picture). In their Communication on p. 4436 ff, H. Kessler and co‐workers show that the carboxyl group previously considered essential for binding can be replaced by a hydroxamic acid unit.
Journals
2009 EN
Puglisi Antonino · Rizzarelli Enrico · Vecchio Graziella
+4 more
The conjugates of β‐cyclodextrins with R‐ or with S‐Etodolac were characterized by NMR spectroscopy, and S‐Etodolac alone was characterized by X‐ray diffraction analysis. In solution, the R‐Etodolac conjugate is soluble in water; the other epimer shows a very low solubility. The NMR characterization of the R‐Etodolac conjugate in D 2 O shows that, in aqueous solution, the Edotolac moiety is self‐included in the cavity, while the NMR characterization in MeOH of both conjugates underlines that, in this solvent, the Etodolac moiety is not included in the CD cavity. The X‐ray structure determination of the S‐Etodolac conjugate reveals a “sleeping swan”‐like shape, with the covalently bonded Etodolac moiety being folded with the 8‐ethyl group inserted inside the hydrophobic cavity of the β‐CD ring. The terminal methyl group of the 8‐ethyl group enters the centre of cavity from the side of the primary hydroxyl groups and is buried inside the β‐CD macrocycle. The terminal methyl group is positioned at a distance of 1.06 Å from the O(4) plane in the side of the primary hydroxyl groups. In addition to van der Waals interactions between the hydrophobic ethyl group and the β‐CD cavity, the folded conformation is further stabilized by one intramolecular H‐bond involving the indole N–H group and the primary hydroxyl group of the glucose unit 7. Along the b axis, the β‐CD molecules are arranged in columns; the macrocycles form a herring bone pattern, so that the cavity of each β‐CD molecule is closed at each end by neighboring molecules. Within the layers, the β‐CD macrocycles are held together by a complicated intermolecular hydrogen bond network, in which numerous water molecules and hydroxyl groups are involved. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 1227–1235, 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 [email protected]
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Journals
2009 EN
Abbate Sergio · Burgi Luigi Filippo · Castiglioni Ettore
+4 more
The electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectra of both enantiomers of naringenin (4′,5,7‐trihydroxyflavanone) in acetonitrile solution have been measured. The enantiomers were obtained by chiral HPLC separation of the racemic sample. DFT calculations have been performed for relevant conformers and subsequent evaluations of VCD spectra are compared with VCD experiments: safe assignment of the absolute configuration is provided, based in particular on the VCD data. The relevance of the rotational conformers of the hydroxyl groups and of the mobility of phenol moiety is studied: based on this, we provide a first interpretation of the observed intense and broad couplet at 1325/1350 cm −1 . Four conformers contribute to this pattern with different sign and amplitude as shown by DFT calculations. Time dependent DFT calculations have been performed and compared with ECD experimental data, under the same assumption of conformational properties and mobilities investigated by VCD. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
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Journals
2009 EN
Abbate Sergio · Longhi Giovanna · Castiglioni Ettore
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The absolute configuration of a newly designed, letrozole‐based chiral aromatase inhibitor that could not be defined by crystallographic techniques has been determined by means of vibrational and electronic circular dichroism and by optical rotation measurements combined with density functional theory calculations on possible conformers. The same absolute configurational assignment can be applied to the individual enantiomeric sulfamate esters, which are derived from the corresponding enantiomers of the chirally separated parent phenols, based on the similarity of the ECD spectrum of the sulfamate derivative to that of its phenolic precursor. The two enantiomeric sulfamate esters studied here are the first examples of nonsteroidal dual aromatase‐sulfatase inhibitor whose activities have been evaluated on optically resolved enantiomers. Chirality 2009. © 2009 Wiley‐Liss, Inc.
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