bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamic and Kinetic Data for Adduct Formation, cis–trans Isomerization and Redox Reactions of ML4 Complexes: A Case study with Rhodium– and Iridium–tropp Complexes in d8, d9 and d10 Valence Electron Configurations (tropp= Dibenzotropylidene Phosphanes)
Authors: Breher Frank , Rüegger Heinz , Mlakar Marina , Rudolph Manfred , Deblon Stephan , Schönberg Hartmut , Boulmaâz Souad , Thomaier Jörg , Grützmacher Hansjörg 
Published: February 2004

AbstractThe formation of adducts of the square‐planar 16‐electron complexes trans‐[M(troppph)2]+ and cis‐[M(troppph)2]+ (M=Rh, Ir; troppPh=5‐diphenylphosphanyldibenzo[a,d]cycloheptene) with acetonitrile (acn) and Cl−, and the redox chemistry of these complexes was investigated by various physical methods (NMR and UV‐visible spectroscopy, square‐wave voltammetry), in order to obtain some fundamental thermodynamic and kinetic data for these systems. A trans/cis isomerization cannot be detected for [M(troppph)2]+ in non‐coordinating solvents. However, both isomers are connected through equilibria of the type trans‐[M(troppph)2]++L⇄[ ML(troppph)2]n⇄cis‐[M(troppph)2]++L, involving five‐coordinate intermediates [ML(troppph)2]n (L=acn, n=+1; L=Cl−, n=0). Values for Kd (Kf), that is, the dissociation (formation) equilibrium constant, and kd (kf), that is, the dissociation (formation) rate constant, were obtained. The formation reactions are fast, especially with the trans isomers (kf>1×105 m−1 s−1). The reaction with the sterically more hindered cis isomers is at least one order of magnitude slower. The stability of the five‐coordinate complexes [ML(troppph)2]n increases with Ir>Rh and Cl−>acn. The dissociation reaction has a pronounced influence on the square‐wave (SW) voltammograms of trans/cis‐[Ir(troppph)2]+. With the help of the thermodynamic and kinetic data independently determined by other physical means, these reactions could be simulated and allowed the setting up of a reaction sequence. Examination of the data obtained showed that the trans/cis isomerization is a process with a low activation barrier for the four‐coordinate 17‐electron complexes [M(troppph)2]0 and especially that a disproportionation reaction 2 trans/cis‐[M(troppph)2]0→[M(troppph)2]++[M(troppph)2]− may be sufficiently fast to mask the true reactivity of the paramagnetic species, which are probably less reactive than their diamagnetic equilibrium partners.
Theoretical Insights into the Role of a Counterion in Copper‐Catalyzed Enantioselective Cyclopropanation Reactions
Authors: Fraile José M. , García José I. , Gil María J. , Martínez‐Merino Víctor , Mayoral José A. , Salvatella Luis 
Published: February 2004

AbstractThe effect of a coordinating counteranion on the mechanism of CuI‐catalyzed cyclopropanation has been investigated extensively for a medium‐sized reaction model by means of theoretical calculations at the B3LYP/6‐31G(d) level. The main mechanistic features are similar to those found for the cationic (without a counteranion) mechanism, the rate‐limiting step being nitrogen extrusion from a catalyst–diazoester complex to generate a copper–carbene intermediate. The cyclopropanation step takes place through a direct carbene insertion of the metal–carbene species to yield a catalyst–product complex, which can finally regenerate the starting complex. However, the presence of the counteranion has a noticeable influence on the calculated geometries of all the intermediates and transition structures. Furthermore, the existence of a preequilibrium with a dimeric form of the catalyst, together with a higher activation barrier in the insertion step, explains the lower yield of cyclopropane products observed experimentally in the presence of chloride counterion. The stereochemical predictions of a more realistic model (made by considering a chiral bis(oxazoline)–copper(i) catalyst) have been rationalized in terms of the lack of significant steric repulsions, and the model shows good agreement with the low enantioselectivities observed experimentally for these kinds of catalytic systems.
Macrocyclic Glycoclusters: From Amphiphiles through Nanoparticles to Glycoviruses
Authors: Aoyama Yasuhiro 
Published: February 2004

AbstractMacrocyclic glycocluster amphiphiles are intended to be a covalent‐bundle mimic of clustering glycolipid motifs on the cell membrane. They are irreversibly micellized to give glycocluster nanoparticles (GNPs); their masked hydrophobicity endows them with remarkable saccharide specificities in the interactions with biological saccharide receptors. The GNPs also exhibit unprecedented hydrogen‐bond capacities; they are agglutinated with Na2HPO4 and assembled on plasmid DNA in a number‐, size‐, and shape‐controlled manner to give artificial glycoviral particles capable of transfection. Thus, the intrinsic function of viruses, that is, cell invasion followed by gene expression, is also intrinsic to size‐regulated (∼50 nm) glycoviruses. The growth of glycocluster amphiphiles through nanoparticles to glycoviruses reveals a hierarchical adhesion control of the saccharide clusters.
Synthesis, Fluorescence and Photoisomerization Studies of Azobenzene‐Functionalized Poly(alkyl aryl ether) Dendrimers
Authors: Nithyanandhan Jayaraj , Jayaraman Narayanaswamy , Davis Riju , Das Suresh 
Published: February 2004

AbstractA series of azobenzene‐functionalized poly(alkyl aryl ether) dendrimers have been synthesized and their photochemical and photophysical properties in solution and as thin films have been investigated. Although the photochemical behavior of the azodendrimers in solution indicated that the azobenzene units behave independently, very similar to the constituent monomer azobenzene unit, the properties of thin solid films of the dendrimers were distinctly different. The azodendrimers, AzoG1, AzoG2, and AzoG3 were observed to form stable supercooled glasses, which showed long‐wavelength absorption and red emission characteristics of J‐aggregates of the azobenzene chromophores. Reversible photoinduced isomerization of the azodendrimers in the glassy state is described.
Synthesis, Characterization and Photochromic Studies of Spirooxazine‐Containing 2,2′‐Bipyridine Ligands and Their Rhenium(i) Tricarbonyl Complexes
Authors: Ko Chi‐Chiu , Wu Li‐Xin , Wong Keith Man‐Chung , Zhu Nianyong , Yam Vivian Wing‐Wah 
Published: February 2004

AbstractA series of spirooxazine‐containing 2,2′‐bipyridine ligands and their rhenium(i) tricarbonyl complexes has been designed and synthesized, and their photophysical, photochromic and electrochemical properties have been studied. The X‐ray crystal structures of two of the complexes have been determined. Detailed studies showed that the emission properties of the complexes could readily be switched through photochromic reactions.
Aqueous‐Solution Growth of GaP and InP Nanowires: A General Route to Phosphide, Oxide, Sulfide, and Tungstate Nanowires
Authors: Xiong Yujie , Xie Yi , Li Zhengquan , Li Xiaoxu , Gao Shanmin 
Published: February 2004

AbstractA general synthetic route has been developed for the growth of metal phosphide, oxide, sulfide, and tungstate nanowires in aqueous solution. In detail, cetyltrimethylammonium cations (CTA+) can be combined with anionic inorganic species along a co‐condensation mechanism to form lamellar inorganic–surfactant intercalated mesostructures, which serve as both microreactors and reactants for the growth of nanowires. For example, GaP, InP, γ‐MnO2, ZnO, SnS2, ZnS, CdWO4, and ZnWO4 nanowires have been grown by this route. To the best of our knowledge, this is the first time that the synthesis of GaP and InP nanowires in aqueous solution has been achieved. This strategy is expected to extend to grow nanowires of other materials in solution or by vapor transport routes, since the nanowire growth of any inorganic materials can be realized by selecting an appropriate reaction and its corresponding lamellar inorganic–surfactant precursors.
A conductivity‐dependent phase transition from closed‐loop to open‐loop dendritic networks
Authors: Smyth David , Hübler Alfred 
Published: January 2004

AbstractMotivated by a principle of minimum dissipation per channel length, we introduce a model for branching, hierarchical networks in an open, dissipative system. Global properties of the resulting structures are observed to scale with the ratio of conductivity in the dendrite material to conductivity in the lattice material. Beyond a critical conductivity ratio, the resulting structures are naturally self‐avoiding and possess scale‐independent branching ratios. Our findings suggest that the conductivity ratio determines the geometric properties of naturally arising dendritic structures. We discuss empirical verification in the context of a system of self‐organizing agglomerates of metal particles in castor oil. © 2004 Wiley Periodicals, Inc. Complexity 9: 56–60, 2004
Life‐like self‐reproducers
Authors: Bilotta Eleonora , Lafusa Antonio , Pantano Pietro 
Published: January 2004

AbstractIn order to understand the interplay among information, genetic instructions, and phenotypic variations, self‐reproducers discovered in two‐dimensional cellular automata are considered as proto‐organisms, which undergo to mutations as they were in a real environmental situation. We realized a computational model through which we have been able to discover the genetic map of the self‐reproducers and the networks they use. Identifying in these maps sets of different functional genes, we found that mutations in the genetic sequences could affect both external shapes and behavior of the self‐reproducers, thus realizing different life‐like strategies in the evolution process. The results highlight that some strategies evolution uses in selecting organisms that are fitting with changing environmental situations maintain the self‐reproducing function, whereas other variations create new self‐reproducers. These self‐reproducers in turn realize different genetic networks, which can be very different from the basic ancestors pools. The mutations that are disruptive bring self‐reproducers to disappear, while other proto‐organisms are generated. © 2004 Wiley Periodicals, Inc. Complexity 9: 38–55, 2004
Leukocyte attraction through the CCR5 receptor controls progress from insulitis to diabetes in non‐obese diabetic mice
Authors: Carvalho‐Pinto Carla , García María I. , Gómez Lucio , Ballesteros André , Zaballos Angel , Flores Juana M. , Mellado Mario , Rodríguez‐Frade José Miguel , Balomenos Dimitrios , Martínez‐A. Carlos 
Published: February 2004

AbstractLymphocyte infiltration to pancreatic islets is associated to chemoattraction, as are other inflammatory autoimmune processes. We examined whether development of insulitis and diabetes dependson chemoattraction of lymphocytes via the CCR5 chemokine receptor. In non‐obese diabetic (NOD) mice, a substantial fraction of peripheral T cells and virtually all B cells expressed high CCR5 levels. CCR5 expression characterized the effector T cell phenotype, suggesting their potential involvement in disease development. In view of these findings and the CCL5 (RANTES, the CCR5 ligand) expression by pancreatic islets, we treated NOD mice with a neutralizing anti‐CCR5 antibody. This did not influence peri‐insulitis advancement, but inhibited β‐cell destruction and diabetes. These data demonstrate a role of CCR5‐dependent chemoattraction in insulitis progression to islet destruction, suggesting the potential value of therapeutic intervention by CCR5 targeting.
Leukemic plasmacytoid dendritic cells share phenotypic and functional features with their normal counterparts
Authors: Chaperot Laurence , Perrot Ivan , Jacob Marie‐Christine , Blanchard Dominique , Salaun Véronique , Deneys Véronique , Lebecque Serge , Brière Francine , Bensa Jean‐Claude , Plumas Joël 
Published: February 2004

AbstractThis work aims to further characterize the newly described leukemic plasmacytoid dendritic cells (LPDC), for which we had previously demonstrated their normal, PDC‐like ability to produce IFN‐α. In addition, LPDC also express the specific antigens BDCA‐2 and BDCA‐4. Importantly, they become fully competent antigen‐presenting cells (APC) after a short maturation induced by IL‐3 + CD40L or virus, exhibiting a characteristic APC phenotype (high expression of CD83 and of the costimulatory molecules CD40, CD80, CD86). Whereas IL‐3 + CD40L‐activated LPDC prime naive CD4+ T cells towards a Th2 pathway (IL‐4‐secreting T cells), virus‐activated LPDC drive a Th1 profile (IFN‐γ–secreting T cells). Moreover, we show in one case that LPDC are able to capture, process and present exogenous antigens, leading to the activation of both CD4+ and CD8+ T cell clones in an antigen‐specific manner. This study further characterizes the phenotype and immunological functions of LPDC.
The anti‐apoptotic factor Bcl‐2 can functionally substitute for the B cell survival but not for the marginal zone B cell differentiation activity of BAFF
Authors: Tardivel Aubry , Tinel Antoine , Lens Susanne , Steiner Quynh‐Giao , Sauberli Estelle , Wilson Anne , Mackay Fabienne , Rolink Antonius G. , Beermann Friedrich , Tschopp Jürg , Schneider Pascal 
Published: February 2004

AbstractThe TNF family ligand B cell‐activating factor (BAFF, BLyS, TALL‐1) is an essential factor for B cell development. BAFF binds to three receptors, BAFF‐R, transmembrane activator and CAML interactor (TACI), and B cell maturation antigen (BCMA), but only BAFF‐R is required for successful survival and maturation of splenic B cells. To test whether the effect of BAFF is due to the up‐regulation of anti‐apoptotic factors, TACI‐Ig‐transgenic mice, in which BAFF function is inhibited, were crossed with transgenic mice expressing FLICE‐inhibitory protein (FLIP) or Bcl‐2 in the B cell compartment. FLIP expression did not rescue B cells, while enforced Bcl‐2 expression restored peripheral B cells and the ability to mount T‐dependent antibody responses. However, many B cells retained immaturity markers and failed to express normal amounts of CD21. Marginal zone B cells were not restored and the T‐independent IgG3, but not IgM, response was impaired in the TACI‐Ig×Bcl‐2 mice. These results suggest that BAFF is required not only to inhibit apoptosis of maturating B cells, but also to promote differentiation events, in particular those leading to the generation of marginal zone B cells.
Microwave‐Assisted Solvent‐Free Synthesis of Hexahydrochromeno[4,3‐b]pyrroles
Authors: Pospíšil Jiří , Potáček Milan 
Published: February 2004

AbstractWe report the microwave‐assisted solvent‐free synthesis of hexahydrochromeno[4,3‐b]pyrroles. Intramolecular 1,3‐dipolar cycloadditions proceed under these conditions within 15 min in 80% yields. Moreover, we have observed pronounced steric requirements of alkyl substituents toward the 1,3‐dipolar cycloadditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Enantioselective Total Synthesis of a trans‐Hydrindane Rings/Side‐Chain Building‐Block of Vitamin D − Asymmetric Induction in an Acid‐Catalyzed Conjugate‐Addition Reaction
Authors: Gorobets Evgueni , Stepanenko Viatcheslav , Wicha Jerzy 
Published: February 2004

AbstractFor the enantioselective total synthesis of 1α,25‐dihydroxyvitamin D3 (3), we have developed an enantioselective approach to the “northern” portion building‐block 8, starting from the optically active hexanoic acid derivative 44, 2‐methylcyclopent‐2‐en‐1‐one (10) and 1‐(phenylthio)but‐3‐en‐2‐one (9). The steric course of the addition reaction of homochiral (S)‐ketene acetals 28, 40, 44 and 58 with 10 was examined. We found that in the cases of 28, 44 and 40, the reactions occur with high simple and induced (facial) diastereoselectivities. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Carcinogen inducibility in vivo and down‐regulation of DMBT1 during breast carcinogenesis
Authors: Mollenhauer Jan , Helmke Burkhard , Medina Daniel , Bergmann Gaby , Gassler Nikolaus , Müller Hanna , Lyer Stefan , Diedrichs Laura , Renner Marcus , Wittig Rainer , Blaich Stephanie , Hamann Ute , Madsen Jens , Holmskov Uffe , Bikker Floris , Ligtenberg Antoon , Carlén Anette , Olsson Jan , Otto Herwart F. , O'Malley Bert , Poustka Annemarie 
Published: January 2004

AbstractDeleted in malignant brain tumors 1 (DMBT1) has been proposed as a candidate tumor suppressor for brain and epithelial cancer. Initial studies suggested loss of expression rather than mutation as the predominant mode of DMBT1 inactivation. However, in situ studies in lung cancer demonstrated highly sophisticated changes of DMBT1 expression and localization, pointing to a chronological order of events. Here we report on the investigation of DMBT1 in breast cancer in order to test whether these principles might also be attributable to other tumor types. Comprehensive mutational analyses did not uncover unambiguous inactivating DMBT1 mutations in breast cancer. Expression analyses in the human and mouse mammary glands pointed to the necessity of DMBT1 induction. While age‐dependent and hormonal effects could be ruled out, 9 of 10 mice showed induction of Dmbt1 expression after administration of the carcinogen 7,12‐dimethybenz(α)anthracene prior to the onset of tumorigenesis or other histopathological changes. DMBT1 displayed significant up‐regulation in human tumor–flanking tissues compared to in normal breast tissues (P < 0.05). However, the breast tumor cells displayed a switch from lumenal secretion to secretion to the extracellular matrix and a significant down‐regulation compared to that in matched normal flanking tissues (P < 0.01). We concluded that loss of expression also is the predominant mode of DMBT1 inactivation in breast cancer. The dynamic behavior of DMBT1 in lung carcinoma is fully reflected in breast cancer, which suggests that this behavior might be common to tumor types arising from monolayered epithelia. © 2003 Wiley‐Liss, Inc.
Identification of cytogenetic subgroups and karyotypic pathways of clonal evolution in follicular lymphomas
Authors: Höglund Mattias , Sehn Laurie , Connors Joseph M. , Gascoyne Randy D. , Siebert Reiner , Säll Torbjörn , Mitelman Felix , Horsman Douglas E. 
Published: January 2004

AbstractFollicular lymphoma (FL) is characterized by the activation ofBCL2through t(14;18)(q32;q21). Additional acquired mutations are necessary to generate a fully malignant clonal proliferation. Many of these secondary genetic alterations are visible in the clonal karyotype; however, the sequence by which they arise and their influence on clinical behavior have not been determined. The ability to address these issues has been hampered by the lack of computational methods to manipulate complex chromosomal data in a sufficiently large cohort of cases. In the present investigation, we analyzed secondary karyotypic alterations in 336 cases of FL with t(14;18) to identify the most common regions of recurrent chromosomal gain or loss. This revealed 29 recurrent changes present in more than 5% of the tumors. Each tumor karyotype was then assessed for the presence or absence of each of these 29 specific changes. By statistical means, we show that the chromosomal changes arise in an apparent temporal order, with distinct early and late changes. We identify, by principal‐components analysis, four possible cytogenetic pathways that characterize the early stages of clonal evolution, which converge to a common route at later stages. We show that FLs with t(14;18) may be classified into cytogenetic subgroups determined by the presence or absence of 6q−, +7, or der(18)t(14;18). Correlation with clinical outcomes in a subset of cases with clinical data revealed del(17p) and +12 to be correlated with an adverse clinical outcome. The clinical implications of these pathways of clonal evolution need to be examined on a prospective basis in a large cohort of FLs. © 2003 Wiley‐Liss, Inc.
Intronic deletion affecting a negative regulatory region of TP73 is related to breast and colorectal carcinomas
Authors: Peña Cristina , Garcia Jose M. , Dominguez Gemma , Silva Javier , Garcia Vanesa , Carcereny Enric , Vargas Javier , Provencio Mariano , España Pilar , Bonilla Felix 
Published: January 2004

AbstractThe TP73 gene encodes a nuclear protein that has high homology with TP53. TP73 is rarely mutated in human cancer. The presence of a 1‐kb regulatory fragment within the first intron of TP73 was recently reported. This fragment exerts silencer activity on TP73 mediated by ZEB. We searched for possible mutations in this negative regulatory region in 45 colorectal and 43 breast cancer patients and in 34 healthy donors. The study was carried out using the SSCP method, and the allelic variants detected were sequenced. The expression of TP73 was analyzed by quantitative RT‐PCR, and loss of heterozygosity (LOH) was assessed by microsatellite study. In several samples, we identified an allele variant that corresponds to a deletion of 73 bp in tumor tissues and normal counterparts, localized between −489 and −417 from the ATG start site of exon 2. Among the 88 tumor samples, 35 (40%) showed at least 1 allele with the cited deletion, versus 7 of the 34 (21%) healthy donors (P = 0.045). When we classified the patients according to the number of variations into homozygous or heterozygous groups, the significance was clearer (P = 0.03). No LOH was detected in the heterozygous cases. There was a positive quantitative correlation between the expression of TP73 and the presence of the allelic variant (P = 0.029). These data suggest that this allelic variant is common in breast and colorectal cancers and that it could alter the expression of the TP73 gene with an additive effect. © 2004 Wiley‐Liss, Inc.
Expression profiling of the influence of RAS mutants on the TGFB1‐induced phenotype of the pancreatic cancer cell line PANC‐1
Authors: Fensterer Heiko , Giehl Klaudia , Buchholz Malte , Ellenrieder Volker , Buck Anita , Kestler Hans A. , Adler Guido , Gierschik Peter , Gress Thomas M. 
Published: January 2004

AbstractExpression profiling analyses were used to elucidate the functional relevance of RAS proteins in mediating the effect of TGFB1 on the transcriptional phenotype of the pancreatic cancer cell line PANC‐1. Despite the presence of one mutated KRAS2 allele in parental PANC‐1 pancreatic cancer cells, RAS‐dependent signal transduction remained susceptible to stimulation by EGF and TGFB1. To analyze the impact of RAS proteins on the TGFB1‐induced transcriptional phenotype, we used PANC‐1 cells stably transfected with a dominant negative HRAS(S17N) mutant or with a constitutively active KRAS2(G12V) mutant. TGFB1 treatment of mock‐transfected PANC‐1 cells led to an expression profile suggestive of epithelial‐mesenchymal transdifferentiation (EMT). Profiling of the HRAS(S17N)‐expressing clone demonstrated that induction of endogenous RAS activity by TGFB1 is required for the development of the TGFB1‐induced transcriptional phenotype of PANC‐1 cells. The expression of the KRAS2(G12V) mutant by itself repressed transcription of markers of epithelial differentiation and induced transcription of several extracellular matrix‐associated genes. This effect was not enhanced further by TGFB1 treatment. In contrast, transcript levels of genes associated with proliferation and cell cycle progression did not appear to be the primary targets of the synergism between the RAS‐ and TGFB1‐dependent cascades. The introduction of the dominant negative and the constitutively active RAS mutants induced partly overlapping and partly inverse effects on the TGFB1‐induced expression profile of PANC‐1 cells. Additional mechanisms such as the induction of autocrine loops and the use of different RAS isoforms or alternate, ERK‐independent signaling pathways may be involved in the interaction between the RAS‐ and the TGFB1‐dependent signaling cascades. © 2004 Wiley‐Liss, Inc.