bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water‐Soluble Arene Ruthenium Complexes Containing a trans‐1,2‐Diaminocyclohexane Ligand as Enantioselective Transfer Hydrogenation Catalysts in Aqueous Solution
Authors: Canivet Jérôme , Labat Gael , Stoeckli‐Evans Helen , Süss‐Fink Georg 
Published: September 2005

AbstractThe cationic chloro complexes [(arene)Ru(H2N∩NH2)Cl]+ (1: arene = C6H6; 2: arene = p‐MeC6H4iPr; 3: arene = C6Me6) have been synthesised from the corresponding arene ruthenium dichloride dimers and enantiopure (R,R or S,S) trans‐1,2‐diaminocyclohexane (H2N∩NH2) and isolated as the chloride salts. The compounds are all water‐soluble and, in the case of the hexamethylbenzene derivative 3, the aqua complex formed upon hydrolysis [(C6Me6)Ru(H2N∩NH2)OH2]2+ (4) could be isolated as the tetrafluoroborate salt. The molecular structures of 3 and 4 have been determined by single‐crystal X‐ray diffraction analyses of [(C6Me6)Ru(H2N∩NH2)Cl]Cl and [(C6Me6)Ru(H2N∩NH2)OH2][BF4]2. Treatment of [Ru2(arene)2Cl4] with the monotosylated trans‐1,2‐diaminocyclohexane derivative (TsHN∩NH2) does not yield the expected cationic complexes, analogous to 1–3 but the neutral deprotonated complexes [(arene)Ru(TsN∩NH2)Cl] (5: arene = C6H6; 6: arene = p‐MeC6H4iPr; 7: arene = C6Me6; 8: arene = C6H5COOMe). Hydrolysis of the chloro complex 7 in aqueous solution gave, upon precipitation of silver chloride, the corresponding monocationic aqua complex [(C6Me6)Ru(TsHN∩NH2)(OH2)]+ (9) which was isolated and characterised as its tetrafluoroborate salt. The enantiopure complexes 1–9 have been employed as catalysts for the transfer hydrogenation of acetophenone in aqueous solution using sodium formate and water as a hydrogen source. The best results were obtained (60 °C) with 7, giving a catalytic turnover frequency of 43 h–1 and an enantiomeric excess of 93 %. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis, Structure and Magnetic Properties of a Novel Linear CuII‐Trimer Complex
Authors: Pashchenko Vladimir , Brendel Bernhard , Wolf Bernd , Lang Michael , Lyssenko Konstantin , Shchegolikhina Olga , Molodtsova Yulia , Zherlitsyna Larisa , Auner Norbert , Schütz Florian , Kollar Marcus , Kopietz Peter , Harrison Neil 
Published: September 2005

AbstractA new hexanuclear copper(II) sandwich complex based on two 10‐membered macrocyclic phenylsiloxanolate ligands, {Cu6[(C6H5SiO2)5]2(OH)2(C10H8N2)2}·4(DMF)·3(H2O) (1), was synthesized and characterized by single‐crystal X‐ray diffraction and measurements of the magnetic susceptibility and isothermal magnetization. The cluster compound crystallizes in the triclinic system, space group P$\bar {1}$ (No. 2), with a = 14.925(3) Å, b = 16.745(2) Å, c = 23.053(3) Å, α = 83.079(9)°, β = 84.836(13)°, γ = 65.019(17)°, and Z = 2. The unit cell contains two identical molecules, each consisting of six interacting Cu2+ (S = 1/2) ions. Within the molecule, the six Cu2+ ions are arranged in two almost linear, parallel trimers. While pairs of oxygen atoms link the Cu2+ ions within the trimers, single oxygen atoms residing at the ends of the trimers provide the strongest intertrimer bonds. Magnetic measurements reveal an antiferromagnetic intratrimer exchange interaction, J/kB = 85 K, as the dominant magnetic coupling of the complex. By introducing a weak antiferromagnetic intertrimer coupling, J′/kB = 3.5 K, a satisfactory description of the magnetic behavior over a wide range of temperature and magnetic field is obtained. The departure of the model curves from the data at the lowest available temperature indicates the presence of additional, weak intra‐ and/or intermolecular interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Library of Peralkylated Bis‐guanidine Ligands for Use in Biomimetic Coordination Chemistry
Authors: Herres‐Pawlis Sonja , Neuba Adam , Seewald Oliver , Seshadri Tarimala , Egold Hans , Flörke Ulrich , Henkel Gerald 
Published: September 2005

AbstractA series of bis‐guanidine ligands designed for use in biomimetic coordination chemistry has been extended to a library matrix combining unprecedented substitutional flexibility within the guanidyl residues with a wide range of aliphatic and aromatic spacers connecting these functionalities. The underlying protocol can be used with predefined ureas as well as secondary amines to build up these units by reaction with phosgene if the ureas are otherwise unavailable. In the latter case, the resulting urea intermediates do not have to be isolated as the reaction proceeds further with additional phosgene to yield a chloroformamidinium chloride which is transformed into the bis‐guanidine functionality by subsequent reaction with a suitable primary diamine in the presence of triethylamine as an auxiliary base. This concept has been used to synthesise and characterise more then two dozen different bis‐guanidines based on 12 discrete monoguanidine units and seven different spacers. These spacers have been chosen such that the most important phenotypes have been dealt with and which range from rigid to more flexible scaffolds. In addition to spacers with no metal‐binding capabilities, other species containing further donor functions such as N‐methyldiphenyleneamine or pyridine‐2,6‐diyl have also been used. The substitution patterns of the guanidine residues can be classified into acyclic and cyclic types. Among the cyclic types, one subset is characterised by five‐ or six‐membered heterocycles containing both the amino nitrogen atoms and another one by individual N‐heterocyclic systems for each amino nitrogen. Structurally characterised examples are 2‐{2‐[2‐(tetramethylguanidi­no)ethoxy]ethoxy}‐1‐(tetramethylguanidino)ethane (TMG2doo) in its diprotonated form and 2,2′‐bis[2N‐(1,1′,3,3′‐tetramethylguanidine)]diphenyleneamine (TMG2PA) as wellas N1,N3‐bis(dimorpholinomethylene)propane‐1,3‐diamine (DMorphG2p) as free bases. For the permethylated bis‐guanidine derivatives, the barrier to rotation around the (C=N)guanidine bond has been determined by means of temperature‐dependent EXSY 1H NMR spectroscopy to range between 54 and 79 kJ mol–1 depending on the type of spacer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Ring Opening of Aziridines with Silylated Nucleophiles under Neutral Conditions
Authors: Wu Jie , Sun Xiaoyu , Xia Hong‐Guang 
Published: September 2005

AbstractRing‐opening of aziridines with silylated nucleophiles in DMF without any catalysts afforded the corresponding products in good to excellent yields under extremely mild reaction conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Development of partial rock veneers by root throw in a subalpine setting
Authors: Osterkamp W. R. , Toy T. J. , Lenart M. T. 
Published: September 2005

AbstractRock veneers stabilize hillslope surfaces, occur especially in areas of immature soil, and form through a variety of process sets that includes root throw. Near Westcliffe, Colorado, USA, data were collected from a 20 × 500 m transect on the east slope of the Sangre de Cristo Mountains. Ages of pit/mound complexes with rock fragments exposed at the surface by root throw ranged from recent (freshly toppled tree) to unknown (complete tree decay). Calculations based on dimensions of the pit/mound complexes, estimated time of tree toppling, sizes of exposed rock fragments, and percentage rock covers at pit/mound complexes, as well as within the transect area, indicate that recent rates of root throw have resulted in only partial rock veneering since late Pleistocene deglaciation. Weathering of rock fragments prevents development of an extensive rock veneer and causes a balance, achieved within an estimated 700 years, between the rates of rock‐fragment exposure by root throw and clast disintegration by chemical reduction. The estimated rate of rock‐fragment reduction accounts for part of the fluvial sediment yields observed for forested subalpine areas of western North America. Copyright © 2005 John Wiley & Sons, Ltd.
Spatial structures of stream and hillslope drainage networks following gully erosion after wildfire
Authors: Moody John A. , Kinner David A. 
Published: September 2005

AbstractThe drainage networks of catchment areas burned by wildfire were analysed at several scales. The smallest scale (1–1000 m2) representative of hillslopes, and the small scale (1000 m2 to 1 km2), representative of small catchments, were characterized by the analysis of field measurements. The large scale (1–1000 km2), representative of perennial stream networks, was derived from a 30‐m digital elevation model and analysed by computer analysis.Scaling laws used to describe large‐scale drainage networks could be extrapolated to the small scale but could not describe the smallest scale of drainage structures observed in the hillslope region. The hillslope drainage network appears to have a second‐order effect that reduces the number of order 1 and order 2 streams predicted by the large‐scale channel structure. This network comprises two spatial patterns of rills with width‐to‐depth ratios typically less than 10. One pattern is parallel rills draining nearly planar hillslope surfaces, and the other pattern is three to six converging rills draining the critical source area uphill from an order 1 channel head. The magnitude of this critical area depends on infiltration, hillslope roughness and critical shear stress for erosion of sediment, all of which can be substantially altered by wildfire. Order 1 and 2 streams were found to constitute the interface region, which is altered by a disturbance, like wildfire, from subtle unchannelized drainages in unburned catchments to incised drainages. These drainages are characterized by gullies also with width‐to‐depth ratios typically less than 10 in burned catchments. The regions (hillslope, interface and channel) had different drainage network structures to collect and transfer water and sediment. Copyright © 2005 John Wiley & Sons, Ltd.
A multi‐level panel STAR model for US manufacturing sectors
Authors: Fok Dennis , van Dijk Dick , Franses Philip Hans 
Published: September 2005

AbstractWe introduce a multi‐level smooth transition model for a panel of time series, which can be used to examine the presence of common nonlinear business cycle features across many variables. The model is positioned in between a fully pooled model, which imposes such common features, and a fully heterogeneous model, which allows for unrestricted nonlinearity. We introduce a second‐stage model linking the parameters that determine the timing of the switches between business cycle regimes to observable explanatory variables, thereby allowing for lead–lag relationships across panel members. We discuss representation, estimation by concentrated simulated maximum likelihood and inference. We illustrate our model using quarterly industrial production in 19 US manufacturing sectors, and document that there are subtle differences across sectors in leads and lags for switches between business cycle recessions and expansions. Copyright © 2005 John Wiley & Sons, Ltd.
Mechanisms of endothelial dysfunction with development of type 1 diabetes mellitus: Role of insulin and C‐peptide
Authors: Joshua Irving G. , Zhang Qin , Falcone Jeff C. , Bratcher Adrienne P. , Rodriguez Walter E. , Tyagi Suresh C. 
Published: September 2005

AbstractComplications associated with insulin‐dependent diabetes mellitus (type‐1diabetes) primarily represent vascular dysfunction that has its origin in the endothelium. While many of the vascular changes are more accountable in the late stages of type‐1diabetes, changes that occur in the early or initial functional stages of this disease may precipitate these later complications. The early stages of type‐1diabetes are characterized by a diminished production of both insulin and C‐peptide with a significant hyperglycemia. During the last decade numerous speculations and theories have been developed to try to explain the mechanisms responsible for the selective changes in vascular reactivity and/or tone and the vascular permeability changes that characterize the development of type‐1diabetes. Much of this research has suggested that hyperglycemia and/or the lack of insulin may mediate the observed functional changes in both endothelial cells and vascular smooth muscle. Recent studies suggest several possible mechanisms that might be involved in the observed decreases in vascular nitric oxide (NO) availability with the development of type‐1 diabetes. In addition more recent studies have indicated a direct role for both endogenous insulin and C‐peptide in the amelioration of the observed endothelial dysfunction. These results suggest a synergistic action between insulin and C‐peptide that facilitates increase NO availability and may suggest new clinical treatment modalities for type‐1 diabetes mellitus. © 2005 Wiley‐Liss, Inc.
Adapter protein CRKII signaling is involved in the rat pancreatic acini response to reactive oxygen species
Authors: Andreolotti Alberto G. , Bragado María J. , Tapia José A. , Jensen Robert T. , Garcia‐Marin Luis J. 
Published: September 2005

AbstractRecent studies demonstrate that reactive oxygen species (ROS) are important mediators of acute pancreatitis, whether induced experimentally or in necrotizing pancreatitis in humans; however, the cellular processes involved remain unclear. Adapter protein CrkII, plays a central role for convergence of cellular signals from different stimuli. Cholecystokinin (CCK), which induces pancreatitis, stimulates CrkII tyrosine phosphorylation and CrkII protein complexes, raising the possibility it can be important in the acinar cell responses to ROS. Therefore, our aim was to investigate whether CrkII signaling is involved in the biological response of rat pancreatic acini to H2O2 and the intracellular mediators implicated. Treatment of isolated rat pancreatic acini with H2O2 rapidly stimulates CrkII phosphorylation, measured as electrophoretic mobility shift and by using a phosphospecific antibody (pTyr221). Tyrosine kinase blocker B44 inhibits the higher phosphorylation state, demonstrating that it occurs mainly in tyrosine residues. H2O2‐induced CrkII phosphorylation is time‐ and concentration‐dependent, showing maximal effect with 3 mM H2O2 at 5 min. The intracellular pathways induced by H2O2 leading to CrkII tyrosine phosphorylation do not involve PKC, intracellular calcium, PI3‐K or the actin cytoskeleton integrity. ROS generation clearly promotes the formation of protein complex CrkII–PYK2. In conclusion, ROS clearly affect the key adapter protein CrkII signaling by two ways: stimulation of CkII phosphorylation and a functional consequence: formation of CrkII–protein complexes. Because of its central role in activating more distal pathways, CrkII might likely play an important role in the ability of ROS to induce pancreatic cellular injury and pancreatitis. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Indian hedgehog: Its roles and regulation in endochondral bone development
Authors: Lai Lick Pui , Mitchell Jane 
Published: September 2005

AbstractNormal endochondral bone development requires the coordination of chondrocyte proliferation and differentiation. Indian hedgehog (Ihh) is a morphogen produced by chondrocytes in the early stage of terminal differentiation and plays several key roles in this process. Ihh regulates growth of adjacent proliferative chondrocytes and can also regulate the rate of differentiation of chondrocytes indirectly through its stimulation of parathyroid hormone‐related protein (PTHrP). In this review, we focus on recent studies that have identified new functions of Ihh and how Ihh itself is being regulated. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Direct activation of TGF‐β1 transcription by androgen and androgen receptor complex in Huh7 human hepatoma cells and its tumor in nude mice
Authors: Yoon Gyesoon , Kim Ji Yeon , Choi Yang Kyu , Won Young Suk , Lim In Kyoung 
Published: September 2005

AbstractImportance of androgen for promotion of hepatocelullar carcinoma (HCC) has long been supported by clinical and experimental evidences. However, mechanisms involved in the carcinogenesis have not yet been fully elucidated. Moreover, unbalanced expression of TGF‐β1 during tumor progression results in prooncogenic rather than growth inhibition. To investigate the effect of androgen on transcriptional regulation of TGF‐β1, we isolated rat TGF‐β1 promoter, based on our previous report (GenBank AF249327), and examined regulation of its promoter activity by dihydrotestosterone in Huh7, LNCaP, and PC3 cells. Several putative transcription factor‐binding sites were found, but no TATA box. When the full‐length (−4784 to +68) and variously deleted promoter DNAs were evaluated, the promoter region spanning from −2732 to −1203 showed the highest activity towards dihydrotestosterone in a dose‐dependent manner in both Huh7 and PC3 cells with androgen receptor (AR) expression. Putative androgen response sequence half site (5′‐TGTCCT‐3′) was identified to be located within −1932 to −1927, proved by mutant (5′‐AGACCT‐3′) analysis and chromatin immunoprecipitation (ChIP) assay. AR mediated upregulation of TGF‐β1 expression was confirmed by HCC developed in nude mice with AR‐overexpressed Huh7‐cells. This work presents in vivo and in vitro evidences of activation of TGF‐β1 expression by androgen and AR, and implicates the modulation of hepatocarcinogenesis by AR through the regulation of TGF‐β1 expression. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Prenylation is not necessary for endogenous Ras activation in non‐malignant cells
Authors: Khwaja Arif , Dockrell Mark E.C. , Hendry Bruce M. , Sharpe Claire C. 
Published: September 2005

AbstractRas monomeric GTPases are pivotal to many core cellular processes such as proliferation and differentiation. The post‐translational prenylation of Ras with a farnesyl or a geranylgeranyl moiety is thought to be critical for its membrane binding and consequent signaling activity. Inhibitors of Ras prenylation have an anti‐proliferative effect in some Ras‐transformed cells. We present a study of the effects of prenylation inhibitors on endogenous, wild‐type Ras in three renal cell types, namely primary adult human renal fibroblasts, primary adult human mesangial cells, and a primate renal fibroblast cell line (Vero cells). We have previously demonstrated that Ras is necessary for normal proliferation in these cells. Here we show that Ras is farnesylated and not geranylgeranylated in all three cell types. Furthermore, inhibiting Ras farnesylation has no effect on cell proliferation or Ras activation. Although inhibiting geranylgeranylation in these cells does inhibit proliferation, this is through an Ras‐independent mechanism. Non‐prenylated Ras is able to localize to the plasma membrane, bind Raf when cells are stimulated by epidermal growth factor or platelet‐derived growth factor, and activate the Ras downstream effectors mitogen‐activated protein kinase and phosphotidylinositol 3‐kinase. We conclude that in wild‐type cells, endogenous Ras does not need to be prenylated to be active. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Regulation of microglial activities by glial cell line derived neurotrophic factor
Authors: Chang Yu‐Ping , Fang Kuan‐Ming , Lee Tsung‐I , Tzeng Shun‐Fen 
Published: September 2005

AbstractMuch attention has been paid to the ability of glial cell line‐derived neurotrophic factor (GDNF) to protect neurons from neurotoxic insults in the central nervous system (CNS). However, little is known about GDNF action on CNS glia that also can express GDNF receptor systems. In this study, we examined the effects of GDNF on primary rat microglia that function as resident macrophages in the CNS and as the source of proinflammatory mediators upon activation. We found that treatment of primary rat microglia with GDNF had no effect on the secretion of the proinflammatory cytokines, tumor necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β), but it increased the nitric oxide (NO) production to some extent. In addition, GDNF increased the enzymatic activity of superoxide dismutase (SOD), the gene expression of surface antigen intercellular adhesion molecule‐1 (ICAM‐1), the production of the integrin α5 subunit, and the phagocytotic capability in primary rat microglia. Furthermore, inhibition of mitogen‐activated protein kinase (Erk‐MAPK) in the mouse microglial cell line BV2 by U0126 indicated that the MAP kinase signaling pathway may be involved in the regulation of NO and integrin α5 production by GDNF. In vivo evidence also showed that amoeboid cells with integrin α5 or with ED1 immunoreactivity appeared in GDNF‐treated spinal cord tissues at the lesion site 1 week post spinal cord injury (SCI). Furthermore, inhibition of Erk‐MAPK in the mouse microglial cell line BV2 by U0126 indicated that the MAP kinase signaling pathway may be involved in the regulation of NO and integrin α5 production by GDNF. Taken together, our results indicate that GDNF has a positive regulatory effect on microglial activities, such as phagocytosis and the upregulation of adhesion molecules. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
C‐type natriuretic peptide enhances osteogenic protein‐1‐induced osteoblastic cell differentiation via Smad5 phosphorylation
Authors: Yeh Lee‐Chuan C. , Zavala Michelle C. , Lee John C. 
Published: September 2005

AbstractIn the present study, we examined the hypothesis that the C‐type natriuretic peptide (CNP) enhances osteogenic protein‐1 (OP‐1) action in stimulating osteoblastic cell differentiation in primary cultures of fetal rat calvaria cell (FRC). CNP enhanced synergistically the OP‐1‐induced Alkaline Phosphatase (AP) activity and mineralized bone nodule formation in a dose‐ and time‐dependent manner. To examine possible mechanism of the synergy between OP‐1 and CNP, the expression levels of key BMP receptors and signaling molecules were examined. Western blot analysis showed that BMPR‐IB and ‐II receptor protein expression was not affected by CNP alone, but was stimulated by OP‐1 alone. The combination of OP‐1 and CNP did not further increase their protein levels. The Runx2 protein expression level was not altered by CNP alone, but was elevated by OP‐1 alone, and was slightly reduced by the combination. The Smad5 protein expression level was slightly decreased by CNP alone, but was stimulated by OP‐1 alone, and was not further stimulated by the combination. Smad5 phosphorylation was not stimulated by CNP alone, but was stimulated significantly by OP‐1 alone. The combination of OP‐1 and CNP further stimulated the OP‐1‐induced Smad5 phosphorylation. Thus, one mechanism of the observed synergy between OP‐1 and CNP involves enhancement of the Smad5 phosphorylation. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.