bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric Synthesis of Aryl Benzyl Sulfoxides by Vanadium‐Catalysed Oxidation: A Combination of Enantioselective Sulfide Oxidation and Kinetic Resolution in Sulfoxide Oxidation
Authors: Kelly Pádraig , Lawrence Simon E. , Maguire Anita R. 
Published: August 2006

AbstractEnantioselective vanadium‐catalysed oxidation of aryl benzyl sulfides using Bolm’s procedure is accompanied by kinetic resolution in the oxidation of the resulting sulfoxides which enhances the enantiopurities of the sulfoxides recovered (typically >90 % ee), albeit with an associated reduction in yield. The effects of ligand, solvent and reaction conditions are discussed in detail.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Highly Selective and Robust Palladium‐Catalyzed Carbon–Carbon Coupling between Allyl Alcohols and Aldehydes via Transient Allylboronic Acids
Authors: Selander Nicklas , Sebelius Sara , Estay Cesar , Szabó Kálmán J. 
Published: August 2006

AbstractThe highly regio‐ and stereoselective coupling of allyl alcohols with aldehydes could be achieved with 5 mol‐% of SeCSe pincer complex catalyst and p‐toluenesulfonic acid in the presence of diboronic acid. The transformations have a broad synthetic scope, and the high yields were obtained without the use of an inert atmosphere and carefully dried solvents.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Essential oils and a novel polyacetylene from Eryngium yuccifolium Michaux. (Apiaceae)
Authors: Ayoub Nahla , Al‐Azizi Mohamed , König Wilfried , Kubeczka Karl‐Heinz 
Published: August 2006

AbstractThe essential oils of Eryngium yuccifolium Michaux. (Apiaceae) were isolated from the leaves, stalks and roots by hydrodistillation. Analysis of the oils by GC and GC–MS revealed that the leaves oil contained 49 compounds, of which germacrene D (18.3%), terpinolene (17.8%), bicyclogermacrene (8.8%), α‐pinene (7.6%), ß‐caryophyllene (6.2%) and falcarinol (9.6%) were found to be the major constituents. In addition, 40 compounds were identified from the stalk oil, among which, germacrene D (38.4%), γ‐amorphene (12.2%), bicyclogermacrene (10.1%), bicyclosesquiphellandrene (3.4%) and falcarinol (3.2%) were the major components. The roots oil was found to contain 25 compounds, of which, terpinolene (25.8%), trans‐β‐bergamotene (18.6%) and the benzaldehyde 2,3,6‐trimethylbenzaldehyde (13.9%), were the major constituents. Yuccifolol (nonadeca‐1,11‐diene‐4,6,8‐triyne‐3,10‐diol), a novel polyacetylene, was isolated and identified from the hexane:ether extract of the aerial parts, together with the known polyacetylenes, falcarinone [heptadeca‐1,9‐(Z)‐dien‐4,6‐diyn‐3‐one], falcarinol (heptadeca‐1,9‐dien‐4,6‐diyn‐3‐ol) and heptadeca‐1,8‐diene‐4,6‐diyne‐3,9‐diol. The chemical structures of these constituents were established by NMR (DEPT, COSY, HMQC and HMBC) as well as HRESI–MS analysis. Copyright © 2006 John Wiley & Sons, Ltd.
Novel bioresorbabale composite fiber structures loaded with proteins for tissue regeneration applications: Microstructure and protein release
Authors: Levy Yair , Zilberman Meital 
Published: August 2006

AbstractNovel bioresorbable core/shell composite fiber structures loaded with proteins were developed and studied. These unique polymeric structures are designed to combine good mechanical properties with a desired controlled protein‐release profile, to serve as scaffolds for tissue regeneration applications. Core/shell fiber structures were formed by “coating” poly(L‐lactic acid) fibers with protein‐containing poly(DL‐lactic‐co‐glycolic acid) porous structures. Shell preparation (coating) was performed by the freeze‐drying of water in oil emulsions. The present study focused on the effect of the emulsion's formulation on the porous shell structure and on the resulting cumulative protein release from the composite fibers for 90 days. Horseradish peroxidase (HRP) was used as the protein source. The release profiles usually exhibited an initial burst effect, accompanied by a decrease in release rate with time, as is typical for diffusion‐controlled systems. The HRP content and the emulsion's organic:aqueous phase ratio exhibited significant effects on both the shell microstructure and the HRP release profile from the composite fibers, whereas the polymer content of the emulsion's organic phase only affected these fiber characteristics in certain cases. Proper selection of the emulsion's parameters can yield core/shell fiber structures with the desired protein release behavior and other useful physical properties. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Glow discharge plasma treatment of polyethylene tubing with tetraglyme results in ultralow fibrinogen adsorption and greatly reduced platelet adhesion
Authors: Cao Lan , Sukavaneshvar Sivaprasad , Ratner Buddy D. , Horbett Thomas A. 
Published: August 2006

AbstractPrevious studies from our lab have shown that fibrinogen adsorption (ΓFg) must be reduced below 10 ng/cm2 to significantly reduce platelet adhesion, and that radio frequency glow discharge (RFGD) treatment of polymeric films in the presence of tetraethylene glycol dimethyl ether (tetraglyme) can reduce ΓFg to the desired ultralow value. In this report, the effects of RFGD coatings of tetraglyme on the lumenal surface of PE tubing on ΓFg and on blood interactions both in vitro and ex vivo are described. ΓFg on the tetraglyme‐coated PE tubing was reduced to the desired ultralow level (<10 ng/cm2), and we also observed a significant decrease in adsorption of von Willebrand's factor. In vitro platelet adhesion from washed platelet suspensions, platelet rich plasma, or whole blood to tetraglyme‐coated PE tubing was decreased compared to PE, polyurethane, or silicone rubber tubes. In addition, thrombin generation by platelets adherent to tetraglyme‐coated PE was also much less than by platelets adherent to PE. When inserted in an ex vivo carotid artery‐carotid artery shunt in sheep, the RFGD tetraglyme‐coated PE exhibited a very low number of adherent platelets compared to heparin‐coated, chromic acid‐etched, or plain PE. The RFGD tetraglyme‐coated PE tubes exhibited high protein and platelet resistance in vitro, and high platelet resistance ex vivo. The improved hemocompatibility is attributed to the unique chemical structure of RFGD tetraglyme that makes it highly protein resistant. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
There exist Steiner triple systems of order 15 that do not occur in a perfect binary one‐error‐correcting code
Authors: Östergård Patric R. J. , Pottonen Olli 
Published: August 2006

AbstractThe codewords at distance three from a particular codeword of a perfect binary one‐error‐correcting code (of length 2m−1) form a Steiner triple system. It is a longstanding open problem whether every Steiner triple system of order 2m−1 occurs in a perfect code. It turns out that this is not the case; relying on a classification of the Steiner quadruple systems of order 16 it is shown that the unique anti‐Pasch Steiner triple system of order 15 provides a counterexample. © 2006 Wiley Periodicals, Inc. J Combin Designs 15: 465–468, 2007
Polyamines, PI(4,5)P2, and actin polymerization
Authors: Coburn Ronald F. , LaBelle Edward F. , Baron Carl B. 
Published: August 2006

AbstractSpermine (SPM) and spermidine (SPD) activate isolated phosphatidylinositol‐4‐phosphate 5‐kinases (PI(4)P5K), enzymes that convert phosphatidylinositol‐4‐phosphate to phosphatidylinositol 4,5‐bisphosphate (PI(4,5)P2). PI(4,5)P2 formation is known to be involved in cellular actin reorganization and motility, functions that are also influenced by polyamines. It has not been proven that endogenous polyamines can control inositol phospholipid metabolism. We evoked large decreases in SPD and putrescine (PUT) contents in HL60 cells, using the ornithine decarboxylase inhibitor, alpha‐difluoromethylornithine (DFMO), which resulted in decreases in PI(4,5)P2 content per cell and inositol phosphate formation to 76.9 ± 3.5% and 81.5 ± 4.0% of control, respectively. Accurately reversing DFMO‐evoked decreases in SPD content by incubating cells with exogenous SPD for 20 min rescued these decreases. DFMO treatment and SPD rescues also changed the ratio of total cellular PI(4,5)P2 to PIP suggesting involvement of a SPD‐sensitive PI(4)P5K. PUT and SPM were not involved in DFMO‐evoked changes in cellular PI(4,5)P2 contents. In DFMO‐treated HL60 cells, the percent of total actin content that was filamentous was decreased to 59.1 ± 5.8% of that measured in paired control HL60 cells, a finding that was rescued following reversal of DFMO‐evoked decreases in SPD and PI(4,5)P2 contents. In slowly proliferating DMSO‐differentiated HL60 cells, inositol phospholipid metabolism was uncoupled from SPD control. We conclude: in rapidly proliferating HL60 cells, but not in slowly proliferating differentiated HL60 cells, there are endogenous SPD‐sensitive PI(4,5)P2 pools, probably formed via SPD‐sensitive PI(4)P5K, that likely control actin polymerization. J. Cell. Physiol. 209: 405–412, 2006. © 2006 Wiley‐Liss, Inc.
Biglycan binds to α‐ and γ‐sarcoglycan and regulates their expression during development
Authors: Rafii Michael S. , Hagiwara Hiroki , Mercado Mary Lynn , Seo Neung S. , Xu Tianshun , Dugan Tracey , Owens Rick T. , Hook Magnus , McQuillan David J. , Young Marian F. , Fallon Justin R. 
Published: August 2006

AbstractThe dystrophin‐associated protein complex (DAPC), which links the cytoskeleton to the extracellular matrix, is essential for muscle cell survival, and is defective in a wide range of muscular dystrophies. The DAPC contains two transmembrane subcomplexes—the dystroglycans and the sarcoglycans. Although several extracellular binding partners have been identified for the dystroglycans, none have been described for the sarcoglycan subcomplex. Here we show that the small leucine‐rich repeat (LRR) proteoglycan biglycan binds to α‐ and γ‐sarcoglycan as judged by ligand blot overlay and co‐immunoprecipitation assays. Our studies with biglycan‐decorin chimeras show that α‐ and γ‐sarcoglycan bind to distinct sites on the polypeptide core of biglycan. Both biglycan proteoglycan as well as biglycan polypeptide lacking glycosaminoglycan (GAG) side chains are components of the dystrophin glycoprotein complex isolated from adult skeletal muscle membranes. Finally, our immunohistochemical and biochemical studies with biglycan null mice show that the expression of α‐ and γ‐sarcoglycan is selectively reduced in muscle from young (P14‐P21) animals, while levels in adult muscle (≥P35) are unchanged. We conclude that biglycan is a ligand for two members of the sarcoglycan complex and regulates their expression at discrete developmental ages. J. Cell. Physiol. 209: 439–447, 2006. © 2006 Wiley‐Liss, Inc.
1,25‐dihydroxyvitamin D3 transcriptionally represses p45Skp2 expression via the Sp1 sites in human prostate cancer cells
Authors: Huang Yu‐Chun , Hung Wen‐Chun 
Published: August 2006

AbstractUpregulation of p27Kip1 protein in 1,25‐dihydroxyvitamin D3‐treated cancer cells is mediated via enhancement of gene transcription and reduction of protein degradation. 1,25‐dihydroxyvitamin D3 inhibits the expression of p45Skp2, the F‐box protein which is implicated in p27Kip1 degradation, to reduce turnover of p27Kip1 protein. In this study, we elucidate the underlying mechanism by which 1,25‐dihydroxyvitamin D3 inhibits p45Skp2 in human LNCaP prostate cancer cells. Western blot and RT‐PCR analysis suggest that 1,25‐dihydroxyvitamin D3 suppresses p45Skp2 via transcriptional repression. Promoter activity assays indicate that 1,25‐dihydroxyvitamin D3 directly inhibits p45Skp2 promoter activity. Deletion analysis shows that 1,25‐dihydroxyvitamin D3 response element is localized at −447/−291 bp region from the translational start site of the p45Skp2 promoter. Mutation analysis suggests that two Sp1 sites localized at −386/−380 and −309/−294 bp region are required for transcriptional repression. Chromatin immunoprecipitation (CHIP) assay demonstrates that VDR indirectly binds to these Sp1 sites in vivo and this binding is increased after 1,25‐dihydroxyvitamin D3 treatment. Re‐CHIP assay suggests that VDR and Sp1 form a complex to bind to the Sp1 sites. DNA affinity precipitation assay (DAPA) shows that histone deacetylase 1 (HDAC1) is recruited to the Sp1 sites after 1,25‐dihydroxyvitamin D3 stimulation. Re‐CHIP assay verifies that binding of Sp1 and HDAC1 to p45Skp2 promoter is enhanced after 1,25‐dihydroxyvitamin D3 treatment. HDAC inhibitor trichostatin A (TSA) reverses the inhibition of p45Skp2 promoter activity by 1,25‐dihydroxyvitamin D3. Collectively, our results suggest that 1,25‐dihydroxyvitamin D3 induces the formation of VDR/Sp1 complex and acts via a Sp1‐ and HDAC1‐depedent pathway to inhibit p45Skp2 transcription. J. Cell. Physiol. 209: 363–369, 2006. © 2006 Wiley‐Liss, Inc.
Activated hepatic stellate cells induce tumor progression of neoplastic hepatocytes in a TGF‐β dependent fashion
Authors: Mikula M. , Proell V. , Fischer A.N.M. , Mikulits W. 
Published: August 2006

AbstractThe development of hepatocellular carcinomas from malignant hepatocytes is frequently associated with intra‐ and peritumoral accumulation of connective tissue arising from activated hepatic stellate cells. For both tumorigenesis and hepatic fibrogenesis, transforming growth factor (TGF)‐β signaling executes key roles and therefore is considered as a hallmark of these pathological events. By employing cellular transplantation we show that the interaction of neoplastic MIM‐R hepatocytes with the tumor microenvironment, containing either activated hepatic stellate cells (M1‐4HSCs) or myofibroblasts derived thereof (M‐HTs), induces progression in malignancy. Cotransplantation of MIM‐R hepatocytes with M‐HTs yielded strongest MIM‐R generated tumor formation accompanied by nuclear localization of Smad2/3 as well as of β‐catenin. Genetic interference with TGF‐β signaling by gain of antagonistic Smad7 in MIM‐R hepatocytes diminished epithelial dedifferentiation and tumor progression upon interaction with M1‐4HSCs or M‐HTs. Further analysis showed that tumors harboring disrupted Smad signaling are devoid of nuclear β‐catenin accumulation, indicating a crosstalk between TGF‐β and β‐catenin signaling. Together, these data demonstrate that activated HSCs and myofibroblasts directly govern hepatocarcinogenesis in a TGF‐β dependent fashion by inducing autocrine TGF‐β signaling and nuclear β‐catenin accumulation in neoplastic hepatocytes. These results indicate that intervention with TGF‐β signaling is highly promising in liver cancer therapy. J. Cell. Physiol. 209: 560–567, 2006. © 2006 Wiley‐Liss, Inc.
Differential role of presenilin‐1 and ‐2 on mitochondrial membrane potential and oxygen consumption in mouse embryonic fibroblasts
Authors: Behbahani Homira , Shabalina Irina G. , Wiehager Birgitta , Concha Hérnan , Hultenby Kjell , Petrovic Natasa , Nedergaard Jan , Winblad Bengt , Cowburn Richard F. , Ankarcrona Maria 
Published: August 2006

AbstractIncreasing evidence indicates that mitochondrial alterations contribute to the neuronal death in Alzheimer's disease (AD). Presenilin 1 (PS1) and Presenilin 2 (PS2) mutations have been shown to sensitize cells to apoptosis by mechanisms suggested to involve impaired mitochondrial function. We have previously detected active γ‐secretase complexes in mitochondria. We investigated the impact of PS/γ‐secretase on mitochondrial function using mouse embryonal fibroblasts derived from wild‐type, PS1−/−, PS2−/− and PS double knock‐out (PSKO) embryos. Measurements of mitochondrial membrane potential (ΔΨm) showed a higher percentage of fully functional mitochondria in PS1−/− and PSwt as compared to PS2−/− and PSKO cells. This result was evident both in whole cell preparations and in isolated mitochondria. Interestingly, pre‐treatment of isolated mitochondria with the γ‐secretase inhibitor L‐685,458 resulted in a decreased population of mitochondria with high ΔΨm in PSwt and PS1−/− cells, indicating that PS2/γ‐secretase activity can modify ΔΨm. PS2−/− cells showed a significantly lower basal respiratory rate as compared to other cell lines. However, all cell lines demonstrated competent bioenergetic function. These data point toward a specific role of PS2/γ‐secretase activity for proper mitochondrial function and indicate interplay between PS1 and PS2 in mitochondrial functionality. © 2006 Wiley‐Liss, Inc.
Tribochemistry of n‐hexadecane in different material systems
Authors: Kajdas Czeslaw , Makowska Monika , Gradkowski Marian 
Published: August 2006

AbstractHexadecane is widely used as the model base oil to investigate both tribological effectiveness and tribochemical reaction mechanisms of various antiwear and extreme pressure additives. On the other hand, it is well known from existing references that hexadecane, similarly to hydrocarbon oils, oxidizes during the lubrication process of tribological systems. It has frequently been pointed out that carboxylic acids are formed which — reacting with rubbing surfaces — generate soaps. Most recent studies, however, demonstrate that the oxidation process under friction conditions is very complex and the major oxidation compounds from hexadecane under boundary friction conditions relate to other oxygenates than carboxylic acids.This paper aims to examine what types of surface compound are generated from the hexadecane lubricant in the friction contact zone. Tribological tests were performed on a ball‐on‐disc tribometer. The discs used were made from several materials (steel, aluminium, brass, bronze). Fourier transform infrared (FTIR) microspectrophotometry and techniques involving a scanning electron microscope equipped with an energy‐dispersive spectrometer were used to analyse tribochemical reaction products formed on different substrates. Analytical results obtained clearly demonstrate a similar tribochemical reaction process operating on all the metals tested. The FTIR results obtained allowed new absorption bands to be discovered and accounted for. These absorption bands have been assigned to specific complex compounds. Copyright © 2006 John Wiley & Sons, Ltd.
Miscibility with Asymmetrical Interactions in Blends of Two Carbonyl‐Containing Polymers: Poly(vinyl acetate) with Aliphatic Polyesters
Authors: Chang Chao‐Shun , Woo Eamor M. , Lin Jia‐Hsien 
Published: August 2006

AbstractSummary: Phase behavior, miscibility, or immiscibility in blends of two polymers with carbonyl groups, PVAc and homologous polyesters of different CH2/CO ratios, were examined using DSC, OM and SEM. Polyesters used in this study included PES, PEA, PPA, and PBA. PVAc/polyester blends were found to be immiscible with distinctly a two‐phase morphology when the polyesters' structural CH2/CO ratios are lower than 3 or higher than 4; whereas miscibility is seen in three blend systems: PVAc/PEA (CH2/CO = 3.0), PVAc/PPA (CH2/CO = 3.5), and PVAc/PBA (CH2/CO = 4.0). Asymmetry in the Tg‐composition relationships is seen in all three miscible blend systems. Such non‐specific, weak and asymmetrical interactions, though sufficient to maintain borderline miscibility in the blends, may be partially responsible for leading to the noted asymmetry in the Tg‐composition relation of the blends. Mechanism and origin of this phenomenon of asymmetry in Tg‐composition relationships in some blends may be still puzzling. Strictly speaking, the non‐equilibrium phenomenon of glass transition may not be ideal for evaluating the strength of intermolecular interactions in blends. Future perfection on more suitable approaches may yet be needed.Tg vs. composition for the miscible PVAc/PPA blend.magnified imageTg vs. composition for the miscible PVAc/PPA blend.
Dynamically Available Volume: A Novel Order Parameter for Dense and Nearly Arrested Systems
Authors: Dawson Kenneth A. , Lynch Iseult , Lawlor Aonghus , de Gregorio Paolo 
Published: August 2006

AbstractSummary: Many common materials ‘solidify’ upon a small change in their surroundings (such as temperature or pH), and the underlying phenomenon is the collective slowing of the motion of the constituent molecules. Examples include gels, polymers, proteins, and other soft matter systems. It has been known for some time that ‘arrest’ is related to some concept of ‘free volume’. However, it has emerged more recently that the important parameter is the volume usable in the long‐ranged reorganisation of the system (the dynamically available volume, DAV) as this determines mobility in these systems. The DAV diminishes as systems arrest, and this is the canonical order parameter for understanding the arrest of complex systems. This idea has been taken a step further here, wherein it is clearly indicated that thermal fluctuation effects can be accommodated within the DAV scenario.Dynamically available volume (DAV) i.e, the empty space that is available to promote long‐ranged motion, and hence diffusion is shown here (the shaded polygonal volume, overemphasized for clarity) to allow the red particle to pass into a neighbouring cage. Repeat of this process is needed for long‐ranged transport (diffusion), and only some DAV is ultimately useful, and therefore termed ‘connected’ DAV.magnified imageDynamically available volume (DAV) i.e, the empty space that is available to promote long‐ranged motion, and hence diffusion is shown here (the shaded polygonal volume, overemphasized for clarity) to allow the red particle to pass into a neighbouring cage. Repeat of this process is needed for long‐ranged transport (diffusion), and only some DAV is ultimately useful, and therefore termed ‘connected’ DAV.
Kinetic Study of Ethylene Polymerization Over Supported Bis(imino)pyridine Iron (II) Catalysts
Authors: Barabanov Artem A. , Bukatov Gennady D. , Zakharov Vladimir A. , Semikolenova Nina V. , Mikenas Tatiana B. , Echevskaja Ljudmila G. , Matsko Michail A. 
Published: August 2006

AbstractSummary: The number of active centers (CP) and propagation rate constants (kP) for polymerization of ethylene with supported catalysts LFeCl2/SiO2, LFeCl2/Al2O3 and LFeCl2/MgCl2 (L = 2,6‐(2,6‐(Me)2C6H3NCMe)2C5H3N), activated by an Al(i‐Bu)3 co‐catalyst, were determined by a method of polymerization inhibition with radioactive 14CO. In contrast to homogeneous systems based on LFeCl2, the supported catalysts are highly active and stable in ethylene polymerization at 70–80 °C. In the presence of hydrogen, the activity of the supported catalysts substantially increases (2–4 fold). The data obtained on the effect of hydrogen on the calculated CP and kP values suggests that for ethylene polymerization without hydrogen, the “dormant” active centers are formed in the catalytic systems. A scheme for the formation of these “dormant” centers and their reactivation in presence of hydrogen is suggested. For the investigated supported catalysts the CP values were found to be only 2 to 4% of the total iron complex content in the catalysts. The kP value for the catalysts prepared using different supports (SiO2, Al2O3 and MgCl2) were close (3.2 × 104 to 4.5 × 104 L · (mol · s)−1 at 70 °C). The support composition affects neither the molecular mass (MM) nor the molecular mass distribution (MMD) of the polymers produced. The obtained CP and kP values and data on the polymer MM and MMD lead to conclusion that the nature of the support has almost no effect on the structure of the active centers and the distribution of their reactivity.Effect of support on the MMD of PE produced over supported LFeCl2 catalysts.magnified imageEffect of support on the MMD of PE produced over supported LFeCl2 catalysts.