bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, in vitro and in vivo Evaluation of a Delivery System for Targeting Anticancer Drugs to the Brain
Authors: El‐Sherbeny Magda A. , Al‐Salem Huda S. , Sultan Maha A. , Radwan Mahasen A. , Farag Hassan A. , El‐Subbagh Hussein I. 
Published: October 2003

AbstractA 1, 4‐dihydropyridine ⇌ pyridinium salt type redox system is described as a general and flexible method for site‐specific and sustained delivery of drugs to the brain. This concept was used in the present investigation as a model to deliver an alkylating antitumor agent into the brain. A bis‐(chloroethyl)amine drug was hooked to 1, 4‐dihydropyridine chemical delivery system (CDS) through an amide linkage. Five newtarget compounds (23—27) of the 1, 4‐dihydropyridine CDS type were synthesized through the reduction of five new pyridinium quaternary intermediates (18—22). The synthesized 1, 4‐dihydropyridines were subjected to various chemical and biological investigations to evaluate their ability to cross the blood‐brain barrier (BBB), and to be oxidized biologically into their corresponding quaternary compounds. The in vitro oxidation studies showed that 1‐benzyl‐3‐{N‐[2‐bis(2‐chloroethyl)aminoethyl]‐carbamoyl}‐1, 4‐dihydropyridine (23) and 1‐(4‐nitrobenzyl)‐3‐{N‐[2‐bis(2‐chloroethyl)aminoethyl ]carbamoyl}‐1, 4‐dihydropyridine (27) could be oxidized into their corresponding quaternary compounds 18 and 22 respectively, at an adequate rate, which ensure the release of the carried anticancer drug. The in vivo studies showed that compound 23 was able to cross the BBB at detectable concentrations. On the other hand, the in vitro alkylation activity studies revealed that 1‐(4‐nitrobenzyl)‐3‐{N‐[2‐bis(2‐chloroethyl)aminoethyl]carbamoyl}pyridinium bromide (22) is an alkylating agent with activity comparable to the known drug chlorambucil.
Dopamine Receptor Ligands. Part VII [1]: Novel 3‐Substituted 5‐Phenyl‐1, 2, 3, 4, 5, 6‐hexahydro‐azepino‐[4, 5‐b]indoles as Ligands for the Dopamine Receptors
Authors: Decker Michael , Lehmann Jochen 
Published: October 2003

AbstractA number of 5‐phenyl‐1, 2, 3, 4, 5, 6‐hexahydro‐azepino‐[4, 5‐b]indoles 3 were synthesized with different substituents at the azepine‐N position (methyl‐, allyl‐, 2‐phenyl‐ethyl‐, cyclopropylmethyl‐ and unsubstituted). Furthermore, the indole‐N‐methylated compound was generated and by using norephedrines and norpseudoephedrines as a chiral pool, 4‐methyl‐5‐phenyl‐1, 2, 3, 4, 5, 6‐hexahydro‐azepino‐[4, 5‐b]indoles were prepared which contained racemisation at the reacting C‐atom. These compounds, as well as the ring‐open amino‐alcohols, were screened for their affinity to the hD1‐, hD5‐, hD2L‐, and hD4‐receptors (ç please check sentence). They had micromolar affinities for the receptors and showed the highest affinity to the D1‐subtype family. The cyclic compounds possessed the highest affinity, with the cyclopropylmethyl‐(3c) and methyl‐substituents (3e) being the most active of the tested compounds. Based on an intracellular cAMP‐assay, the unsubstituted compound (at the azepine‐N position) turned out to be an agonist for the D1‐and D5‐subtype family, whereas the substituted compounds showed (partial) agonistic, or even inverse agonistic activity.
The detached eclipsing binary system GX Geminorum
Authors: Sánchez‐Bajo F. , Garrigós‐Sánchez A. , Gómez‐Forrellad J.M. , Nomen‐Torres J. , Kleikamp W. , Frank P. , Moschner W. , Quester W. , García‐Melendo E. 
Published: October 2003

AbstractResults of the photometric analysis by means of the Wilson‐Devinney method, combined with an empirical massradius relation for LC IV stars support the hypothesis that GX Gem is a well detached evolved system of subgiant stars. The solution is consistent with the known spectroscopic parameters obtained by Popper (1996) and the photometric data of Lacy (2002a). (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new light‐time effect study of AR Aurigae
Authors: Albayrak B. , Ak T. , Elmasli A. 
Published: October 2003

AbstractA period study of the young binary AR Aur based on the extensive series of published photoelectric/ccd minima times indicates the cyclic (O – C) variation for the system. This continuous oscillatory variation covers almost three cycles, about 6000 orbital periods, by the present observational data. It can be attributed to the light‐time effect due to a third body with a period of 23.68 ± 0.17 years in the system. The analysis yields a light‐time semi‐amplitude of 0.0084 ± 0.0002 day and an orbital eccentricity of 0.20 ± 0.04. Adopting the total mass of AR Aur, the mass of the third body assumed in the co‐planar orbit with the binary is M3 = 0.54 ± 0.03 M⊙ and the semimajor axis of its orbit is a3 = 13.0 + 0.2 AU. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spot modelling of the flare M4.5 dwarf YZ CMi
Authors: Zboril M. 
Published: October 2003

AbstractWe report on a photometric study of the flareM4.5 dwarf YZ CMi as based on photoelectric observations from the seasons 1972/73, 1979/80 and 1996/97. We suggest spot activity to explain the light and colour curves. Spots are generally 500K cooler than the surrounding photosphere and there are basically two solutions available for the observations: high latitude spot changing slightly basic properties such as radius and latitude or active near‐equatorial (belt‐like) centers represented by three spots. However, the activity centers changed in longitudes (∼180°). The typical spot coverage (inclination i = 60°) is 10‐15% and 5% for the season 1996/97 or ∼25% for the stellar inclination i = 75°. As a by‐product, V curve and (V‐I) and (V‐K) indexes turn out to be most promising in modelling of M‐type stars as far as present calibrations are concerned. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sodium enrichment of the stellar atmospheres. II. Galactic Cepheids
Authors: Andrievsky S.M. , Egorova I.A. , Korotin S.A. , Kovtyukh V.V. 
Published: October 2003

AbstractThe present paper is a continuation of our study of the sodium abundance in supergiant atmospheres (Andrievsky et al. 2002a). We present the results on the NLTE abundance determination in Cepheids, and the derived relation between the sodium overabundance and their masses. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Note on the spatial distribution of old open clusters
Authors: Schmidt K.‐H. 
Published: October 2003

AbstractUsing the sample of 74 old open clusters compiled by Friel (1995) the increase of the mean distance from the galactic plane with cluster age has been determined. The result is in a qualitative agreement with the hypothesis of scattering of the clusters during encounters with massive molecular clouds and by spiral arms. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Velocity dispersion in N‐body simulations of CDM models
Authors: Domínguez A. 
Published: October 2003

AbstractThis work reports on a study of the spatially coarse‐grained velocity dispersion in cosmological N‐body simulations (OCDM and ΛCDM models) as a function of time (redshifts z = 0–4) and of the coarsening length (0.6–20 h−1 Mpc). The main result is the discovery of a polytropic relationship ℐ1 ∝ ϱ2–η between the velocity‐dispersion kinetic energy density of the coarsening cells, ℐ1, and their mass density, ϱ. The exponent η, dependent on time and coarsening scale, is a compact measure of the deviations from the naive virial prediction ηvirial = 0. This relationship supports the “polytropic assumption” which has been employed in theoretical models for the growth of cosmological structure by gravitational instability. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flare stars in the TW Hydrae association: the HIP 57269 system
Authors: König B. , Neuhäuser R. , Guenther E. W. , Hambaryan V. 
Published: October 2003

AbstractWe discuss a new member candidate of the TW Hydrae association (TWA) among the stars of the Gershberg et al. (1999) flare star catalog. TWA is one of the closest known associations of young stars at about 60 pc. Three supposedly young flare stars are located in the same region of the sky as TWA. One of them (HIP 57269) shows strong lithium absorption with spectral type K1/K2V and a high level of chromospheric and coronal activity. It is located at a distance of 48.7 ± 6.3 pc in common with the five TWA members observed with Hipparcos (46.7 to 103.9 pc). HIP 57268 A has a wide companion C which also shows lithium absorption at 6707 Å and which has common proper motion with HIP 57269, as well as a close companion resolved visually by Tycho. HIP 57269 A&C lie above the main sequence and are clearly pre‐main‐sequence stars. The UVW‐space velocity is more consistent with the star system being a Pleiades super cluster member. The two other flare stars in the TWA sky region do not show lithium at all and are, hence, unrelated. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An infrared imaging search for low‐mass companions to members of the young nearby β Pic and Tucana/Horologium associations
Authors: Neuhäuser R. , Guenther E.W. , Alves J. , Huélamo N. , Ott Th. , Eckart A. 
Published: October 2003

AbstractWe present deep high dynamic range infrared images of young nearby stars in the Tucana/Horologium and β Pic associations, all ∼10 to 35 Myrs young and at ∼10 to 60 pc distance. Such young nearby stars are well‐suited for direct imaging searches for brown dwarf and even planetary companions, because young sub‐stellar objects are still self‐luminous due to contraction and accretion. We performed our observations at the ESO 3.5m NTT with the normal infrared imaging detector SofI and the MPE speckle camera Sharp‐I. Three arc sec north of GSC 8047‐0232 in Horologium a promising brown dwarf companion candidate is detected, which needs to be confirmed by proper motion and/or spectroscopy. Several other faint companion candidates are already rejected by second epoch imaging. Among 21 stars observed in Tucana/Horologium, there are not more than one to five brown dwarf companions outside of 75 AU (1.5″ at 50 pc); most certainly only ≤5% of the Tuc/HorA stars have brown dwarf companions (13 to 78 Jupiter masses) outside of 75 AU. For the first time, we can report an upper limit for the frequency of massive planets (∼10 Mjup) at wide separations (∼100 AU) using a meaningfull and homogeneous sample: Of 11 stars observed sufficiently deep in β Pic (12 Myrs), not more than one has a massive planet outside of ∼100 AU, i.e. massive planets at large separations are rare (≤9%). (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Proper motion and X‐ray selected search for new members of the young TW Hya association
Authors: Tachihara K. , Neuhäuser R. , Frink S. , Guenther E. 
Published: October 2003

AbstractWe have searched for new members of the TWHya association (TWA) among unidentified ROSAT X‐ray sources by identifying them in proper motion catalogues and selecting those that would be consistent with kinematical membership to the TWA. Spectroscopic follow‐up observations of 19 member candidates revealed the detection of moderate lithium absorption lines for the following three stars: GSC 7206 845, TYC 7216‐55, and TYC 7247‐12. The isochronal ages of the latter TYC stars are estimated to be ∼20 Myr while the other one has ∼100 Myr age based on a kinematic distance estimate that assumes TWA membership. However, the moderately Li‐rich stars are not likely to be new pre‐main sequence members of TWA partly because of the discrepant radial velocities. Infrared follow‐up imaging in the H‐band for the 3 stars shows companion candidates near two of them.While one system (TYC 7216‐55) is probably a near‐equal‐magnitude stellar binary, our follow‐up H‐band spectrum of the faint companion candidate near GSC 7206 845 shows that it is instead a background K‐type star rather than a companion. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A multiple galaxy collision in compact groups
Authors: Tovmassian H.M. 
Published: October 2003

AbstractIt is shown that the dynamical paradox of the HCG 90, which is treated as an old, and at the same time, as a young system (White et al), may be solved assuming that it is a rotating system in which multiple collisions have occurred during Hubble time. In the frames of the same scenario a multiple collisions in SQ (HCG 92) are naturally explained. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mass ratio limit for primordial black holes
Authors: Brosche P. , Lentes F.‐Th. , Tassie L. J. 
Published: October 2003

AbstractWe augment our scenario for the formation of astronomical objects from macroscopic superstrings by the assumption that the central matter keeps its identity in the fragmentation. From the condition that the angular momentum per mass squared of this matter should be less than the Kerr limit G/c, we obtain upper limits for the ratio of the mass of central black holes M(BH) to the mass M of the host object. This limit is M(BH)/M ≈ 0.001, and, expressed in observed quantities, approximately M(BH)/M ≈ σ2/(v · c) where σ is the r.m.s. velocity, v the rotational velocity and c the velocity of light. The valuesM(BH) agree with the observed behaviour both in order of magnitude and in the variation with velocity dispersion. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hoch hinaus: Schüler forschen unter Weltraumbedingungen II
Authors: Meissner Klaus , Schwertner Jürgen , Hanke Wolfgang 
Published: October 2003

AbstractMit Unterstützung des DLR nahmen Stuttgarter Schüler an einer Parabelflugmission teil. Durch ihr Engagement und den erfolgreich durchgeführten Regenwurmversuch haben sie bewiesen, dass derartige Projekte für alle Beteiligten von Vorteil sein können. Die Untersuchung der Schwerkraftabhängigkeit biologischer Systeme wird auch in Zukunft Kernpunkt der Zusammenarbeit zwischen der Universität Hohenheim und dem Wilhelms‐Gymnasium in Stuttgart bleiben.
Die funktionelle Bedeutung der Artenvielfalt: Biodiversität
Authors: Schmid Bernhard 
Published: October 2003

AbstractEin Zusammenhang zwischen Artenzahl und Funktionsfähigkeit von Ökosystemen lässt sich nur nachweisen, wenn die Artenzahl in Versuchen experimentell reduziert (oder erhöht) wird. Solche Versuche wurden in den vergangenen zehn Jahren durchgeführt und zeigten zahlreiche positive Effekte der Biodiversität auf Ökosysteme. Die Erklärung für diese Effekte reicht von einem einfachen statistischen Auswahl‐Mechanismus, bei dem artenreiche Systeme mit größerer Wahrscheinlichkeit besonders leistungsfähige, dominante Arten enthalten, bis zu einer vollständigen Arbeitsteilung zwischen Arten, die gemeinsam eine höhere Leistung erbringen können, als es die einzelnen Monokulturen tun würden. Die Wirklichkeit liegt zwischen diesen beiden Extremen und hängt sowohl von der Größe des Biotopraumes wie dem Grad der Nischendifferenzierung zwischen den Arten ab. Die funktionelle Bedeutung der Artenvielfalt stellt ein immenses Potential dar, das in Zukunft auch landwirtschaftlich genutzt werden sollte.
Zwischen glasklar und grauem Star: Augenlinse
Authors: Dahm Ralf 
Published: October 2003

AbstractDie Linse des Auges ist vollkommen durchsichtig. Durchsichtigkeit ist in der Natur ein sehr seltenes Phänomen, das in den meisten Fällen auf einer von zwei Anpassungen beruht: Das durchsichtige Gewebe ist sehr dünn oder es besteht fast nur aus Wasser. Die Linse musste andere Wege finden, um durchsichtig zu werden. Ihre Zellen sind außerordentlich hoch spezialisiert, um Licht ungehindert durchfallen zu lassen. Doch diese Spezialisierung birgt auch immer die Gefahr, dass die Zellen sich trüben und ein grauer Star entsteht. Graue Stare können das Sehvermögen stark einschränken. Sogar das Werk des Impressionisten Claude Monet wurde nachhaltig durch seine getrübten Linsen beeinflusst. Die einzige Möglichkeit, graue Stare zu behandeln ist die operative Entfernung der Linse.
Das Kambrium: Als das Leben „explodierte”︁ und eine völlig neue Welt entstand
Authors: Elicki Olaf 
Published: October 2003

AbstractDas Kambrium repräsentiert den frühesten Zeitabschnitt der Erdgeschichte, welcher uns durch die Überlieferung von Fossilien eine detaillierte Rekonstruktion der damaligen Lebens‐ und Sedimentationsräume ermöglicht. Nach oberproterozoischen Vereisungsphasen stellte sich mit dem Kambrium ein „warm house”︁‐Klima ein; bedeutende globale Meeresspiegelanstiege und paläogeographische Veränderungen schufen den Rahmen für die „Kambrische Explosion”︁. Während dieser innovativsten Phase der Evolution erschienen innerhalb eines geologische relativ kurzen Zeitraumes alle heute bekannten (zuzüglich kurz darauf wieder erloschener) tierischen Baupläne — einschließlich der ersten Chordaten. Diese explosionsartige Diversifizierung der Lebewelt führte zu grundlegenden Neustrukturierungen globaler Stoffkreisläufe und veränderte die Sphären unseres Planeten nachhaltig. Mit dem Einsetzen des Kambriums entstanden die uns heute noch vertrauten Grundmuster ökologischer Zusammenhänge sowie — mit der Räuber‐Beute‐Beziehung — ein neuer hocheffizienter Evolutionsmotor.
Weltweites Netzwerk von Baumkronen‐Observatorien
Authors: Irsch Wilhelm 
Published: October 2003

AbstractDie Artenvielfalt in den Baumkronen der Wälder ist immens. Ein weltweites Netzwerk aus 20 Baumkronen‐Observatorien soll in den kommenden 20 Jahren die Biodiversität und die Auswirkungen der globalen Veränderungen in den Baumkronen beobachten.
Magenbakterium mit Langstreckenwaffe
Authors: Gebert Bettina 
Published: October 2003

AbstractDas Bakterium Helicobacter pylori nistet sich in die Magenschleimhaut ein und löst eine meist symptomlose Gastritis aus. Etwa 50 Prozent der Weltbevölkerung sind chronisch mit H. pylori infiziert, 15 bis 20 Prozent der Infizierten entwickeln im Laufe der Jahre Folgekrankheiten wie Magen‐ und Zwölffingerdarmgeschwüre oder ein Magenkarzinom. Weitgehend unverstanden war bisher die Frage, warum H. pylori den Magen auf Dauer besiedeln kann und nicht durch das Immunsystem eliminiert wird. Forscher am Max‐von‐Pettenkofer Institut für Hygiene und Medizinische Mikrobiologie in München fanden heraus, dass ein Toxin von H. pylori die Aktivierung der T‐Zellen hemmt.
Zum Fressen gern
Authors: Wendler Silke 
Published: October 2003

AbstractÜblicherweise werden Hochzeitsgeschenke wie bereits fertig gestellte Nester, Beutetiere oder Drüsensekrete von den Männchen dargeboten. Bei dem Wasserläufer Phoreticovelia disparata, der tropische Flüsse Australiens bewohnt, ist das anders: Hier füttern die Weibchen die Männchen durch.
Anpassungen und Vielfalt im Pikoplankton
Authors: Brennicke Axel 
Published: October 2003

AbstractAls „Pikoplankton”︁ werden die kleinsten photosynthetisch aktiven Bewohner der Meere bezeichnet. Erst vor gut zwanzig Jahren wurden diese enorm wichtigen Zwerge entdeckt, die den Anfang der Nahrungskette im Meer bilden. Die jetzt veröffentlichten vollständigen Genomsequenzen von verschiedenen Vertretern dieser Bakterien zeigen eine erstaunliche genetische Anpassung der Winzlinge an die Lebensbedingungen in unterschiedlichen Wassertiefen durch Mutation, Genverdoppelung und sogar durch Transfer von genetischen Informationen zwischen verschiedenen Spezies.
Karl August Möbius und Friedrich Dahl
Authors: Buschbaum Christian , Saier Bettina , Reise Karsten 
Published: October 2003

Abstract„Biozönose”︁ und „Biotop”︁ sind heute für jeden Biologiestudenten feste Begriffe und haben spätestens mit der Umweltbewegung in den 1980er Jahren auch Einzug in unsere Umgangssprache gefunden. Ihr Ursprung geht aber weit zurück und ist untrennbar mit dem deutschen Lehrer und Zoologen Karl August Möbius und seinem Schüler Friedrich Dahl verbunden.
Gap junctions in the inner ear: Comparison of distribution patterns in different vertebrates and assessement of connexin composition in mammals
Authors: Forge Andrew , Becker David , Casalotti Stefano , Edwards Jill , Marziano Nerissa , Nevill Graham 
Published: October 2003

AbstractThe distribution and size of gap junctions (GJ) in the sensory epithelia of the inner ear have been examined in a reptile (gecko), birds (chicken and owl), and mammals (mouse, guinea pig, gerbil, and bat), and the connexin composition of GJs in the mammalian inner ear has been assessed. Freeze fracture revealed a common pattern of GJ distribution in auditory and vestibular sensory epithelia in the different vertebrate classes. In all these tissues, GJs are numerous, often occupying more than 25% of the plasma membrane area of supporting cells and sometimes composed of more than 100,000 channels. Screening for 12 members of the connexin family in the mammalian inner ear by RT‐PCR, Western blotting, and immunohistochemistry revealed four connexin isotypes, cx26, cx30, cx31, and cx43, in the cochlea and three, cx26, cx30, and cx43, in the vestibular organs. With antibodies characterised for their specificity, cx26 and cx30 colocalised in supporting cells of the organ of Corti, in the basal cell region of the stria vascularis, and in type 1 fibrocytes of the spiral ligament. No other connexin was detected in these regions. Cx31 was localised among type 2 fibrocytes below the spiral prominence, a region where cx30 was not expressed and cx26 expression appeared to be low. Cx43 was detected only in the region of “tension fibrocytes” lining the inner aspect of the otic capsule. This suggests separate functional compartments in the cochlea. In addition to cx26 and cx30, cx43 was detected in supporting cells of the vestibular sensory epithelia. Where cx26 and cx30 were colocalised, double immunogold labelling of thin sections showed both cx26 and cx30 evenly distributed in individual GJ plaques, a pattern consistent with the presence of heteromeric connexons. Coimmunoprecipitation of cochlear membrane proteins solubilised with a procedure that preserves the oligomeric structure of connexons confirmed the presence of heteromeric cx26/cx30 connexons. Heteromeric cx26/cx30 connexons may be unique to the inner ear, which could be one factor underlying the non‐syndromic character of the deafness caused by mutations in cx26. J. Comp. Neurol. 467:207–231, 2003. © 2003 Wiley‐Liss, Inc.