bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of dissolved oxygen on the production and the glycosylation profile of recombinant human erythropoietin produced from CHO cells
Authors: Restelli Veronica , Wang Ming‐Dong , Huzel Norman , Ethier Martin , Perreault Helene , Butler Michael
Published: March 2006

Human recombinant erythropoietin (rHuEPO) was produced from Chinese hamster ovary (CHO) cells transfected with the human EPO gene. The cells were grown in batch cultures in controlled bioreactors in which the set‐points for dissolved oxygen varied between 3% and 200%. The cell‐specific growth rate and final cell yield was significantly lower under hyperoxic conditions (200% DO). However, there was no significant difference in growth rates at other oxygen levels compared to control cultures run under a normoxic condition (50% DO). The specific productivity of EPO was significantly lower at a DO set‐point of 3% and 200% but maintained a consistently high value between 10% to 100% DO. The EPO produced under all conditions as analyzed by two‐dimensional electrophoresis showed a molecular weight range of 33 to 37 kDa and a low isoelectric point range of 3.5 to 5.0. This corresponds to a highly glycosylated and sialylated protein with a profile showing at least seven distinct isoforms. The glycan pattern of isolated samples of EPO was analyzed by weak anion exchange (WAX) HPLC and by normal‐phase HPLC incorporating sequential digestion with exoglycosidase arrays. Assigned structures were confirmed by mass spectrometry (MALDI‐MS). The most prominent glycan structures were core fucosylated tetranntenary with variable sialylation. However, significant biantennary, triantennary, and non‐fucosylated glycans were also identified. Detailed analysis of these glycan structures produced under variable dissolved oxygen levels did not show consistently significant variations except for the ratio of fucosylated to non‐fucosylated isoforms. Maximum core fucosylation (80%) was observed at 50% and 100% DO, whereas higher or lower DO levels resulted in reduced fucosylation. This observation of lower fucosylation at high or low DO levels is consistent with previous data reported for glycoprotein production in insect cells. © 2006 Wiley Periodicals, Inc.
ASCA: analysis of multivariate data obtained from an experimental design
Authors: Jansen Jeroen J. , Hoefsloot Huub C. J. , van der Greef Jan , Timmerman Marieke E. , Westerhuis Johan A. , Smilde Age K.
Published: March 2006

Recently analysis of variance (ANOVA)‐simultaneous component analysis (ASCA) has been introduced as an explorative tool for the analysis of multivariate data with an underlying experimental design [Smilde et al. Bioinformatics 2005; 21: 3043–3048]. This paper focuses on the general methodological framework of ASCA. The drawbacks of other methods for the analysis of this type of data are discussed, as well as the advantages of ASCA above these other methods. Three case studies are used to illustrate the use of ASCA. The relationship between ASCA and several other multivariate data analysis techniques is demonstrated. Finally, possible extensions for ASCA are presented, including multiway analysis and multivariate regression. Copyright © 2006 John Wiley & Sons, Ltd.
A strategy for finding relevant clusters; with an application to microarray data
Authors: Berget Ingunn , Mevik Bjørn‐Helge , Vebø Heidi , Næs Tormod
Published: March 2006

Cluster analysis is a helpful tool for explorative analysis of large and complex data. Most clustering methods will, however, find clusters also in random data. An important aspect of cluster analysis is therefore to distinguish real and artificial clusters, as this will make interpretation of the clusters easier. In some cases, certain types of clusters are more interesting than others. When working with gene expression data, examples of such clusters are gene clusters with high between‐sample variability or clusters with a certain expression profile. Here we present a strategy with the ability to search for such clusters. The clustering is done sequentially. For each sequence, the data is separated into ‘interesting’ and ‘rest’ using the fuzzy c‐means algorithm with noise clustering. The interesting cluster is defined by adding a penalty function to the usual clustering criterion. The penalty function is constructed in such a way that clusters without the interesting properties are given a high penalty. The strategy is presented in a general frame, and can be adjusted by defining different criteria for each type of cluster that is of interest. The methodology is presented and demonstrated in the context of microarray gene expression analysis, using real and simulated data, but can be used for any type of data where cluster analysis may be a helpful tool. Copyright © 2006 John Wiley & Sons, Ltd.
Spectrum analysis by recursively pruned extended auto‐associative neural network
Authors: Linker Raphael
Published: March 2006

A method for automatic analysis of high‐dimensional spectra is presented. The method is based on a so‐termed extended auto‐associative neural network, which is an auto‐associative (bottleneck) neural network with an additional output that corresponds to the response variable of interest. The input of the neural network consists of the absorbance at selected wavelengths. Once the model has been calibrated, the contribution of each input is estimated, the least contributing input and the corresponding output are removed (pruned), and the training procedure is repeated. This procedure leads to a compact non‐linear mapping between the absorbance at a few wavelengths and the response variable of interest. The auto‐associative architecture of the model prevents the overparametrization and overfitting that occur in straightforward mapping between spectra and variable of interest. Overparametrization and overfitting are further reduced by retaining only the inputs required for predicting the variable of interest. The method is illustrated on two case studies involving mid‐infrared absorbance spectra. The results are compared to those obtained with partial least squares (PLS) and principal component analysis (PCA) followed by a neural network. In both case studies, the proposed approach leads to models with fewer parameters and smaller prediction errors. Copyright © 2006 John Wiley & Sons, Ltd.
A comparison of methods for testing differences in predictive ability
Authors: Cederkvist Henrik René , Aastveit Are Halvor , Næs Tormod
Published: March 2006

This paper is devoted to the comparison of methods for testing difference in prediction ability of regression‐based predictors. Focus is on both parametric and non‐parametric methods. Comparisons are done using the bootstrap based on residuals from real data sets. The power of the methods for different alternatives is the main tool for evaluating the properties of the methods. The main conclusion from the bootstrap simulations is that the most suitable method seems to be two‐way analysis of variance of the absolute values of the prediction errors. Copyright © 2006 John Wiley & Sons, Ltd.
Introducing multi‐dimensional ‘hybrid wavelets’ for enhanced evaluation of hyperspectral image cubes and multi‐way data sets
Authors: Vogt Frank , Cramer Jeff , Booksh Karl
Published: March 2006

Multi‐dimensional wavelet transforms (WTs) have been introduced for efficient data compression in order to accelerate chemometric calculations and to reduce requirements for data storage space. For hyphenated measurement techniques or hyperspectral imaging this wavelet compression becomes vital because such sensors acquire unprecedented amounts of information in short periods of time. Conventional, multi‐dimensional wavelet compression uses the same wavelet for all dimensions. However, from a mathematical perspective there is no need for this restriction as the transforms in different dimensions are independent from each other. This manuscript presents multidimensional ‘hybrid wavelet transforms’, which utilize different wavelet types for different dimensions. Thus, hybrid wavelets optimize wavelet compression by adjusting WTs to the different types of data sets. In this manuscript we demonstrate that hybrid wavelets improve acceleration factors compared to conventional multi‐dimensional wavelet compression and determine more precise models. Combinations of Haar, Daub4, Daub6, Daub8, Daub10, Daub12, Daub14, Daub16, Daub18 and Daub20 wavelets are considered in this study. Data obtained with two different experimental techniques are used for assessing hybrid wavelet compression: (i) a data cube obtained by means of mid‐infrared hyperspectral imaging; (ii) data acquired by excitation‐emission matrix (EEM) fluorescence spectroscopy in photo‐catalytic studies. For the hyperspectral data cube hybrid wavelets were found, which are superior regarding acceleration and model quality to all 10 conventional WTs (Haar–Daub20). For the EEM example this was achieved in 9 out of 10 cases; thus in 19 out of 20 investigated cases hybrid WTs were found to be superior to conventional wavelet compression. Copyright © 2006 John Wiley & Sons, Ltd.
Facile, alternative route to Lubeluzole, its enantiomer, and the racemate
Authors: Bruno Claudio , Carocci Alessia , Catalano Alessia , Cavalluzzi Maria M. , Corbo Filomena , Franchini Carlo , Lentini Giovanni , Tortorella Vincenzo
Published: March 2006

Lubeluzole [(S)‐9] has been synthesized by a convergent synthesis, alkylation ofN‐methyl‐N‐piperidin‐4‐yl‐1,3‐benzothiazol‐2‐amine (4) with (+)‐(R)‐1‐chloro‐3‐(3,4‐difluorophenoxy)propan‐2‐ol [(+)‐(R)‐8] being the key step. Alcohol (+)‐(R)‐8was obtained from commercially available (R)‐epichlorohydrin [(R)‐6], while the thiazole derivative4was easily obtained starting fromN‐protected piperidin‐4‐one (1) in a three‐step procedure. The same method was used in order to obtain both the (R)‐stereoisomer of lubeluzole [(R)‐9] and its racemate [(RS)‐9]. Overall yields ranged from 20% to 35%. The enantiomeric excess values for (S)‐9and (R)‐9were 97% and 94% respectively, as analyzed by chiral HPLC. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Solid‐state ESR differentiation between racemate versus enantiomer
Authors: Levkin Pavel A. , Kokorin Alexander I. , Schurig Volker , Kostyanovsky Remir G.
Published: March 2006

Noticeable differences between solid‐state ESR spectra of enantiopure and racemic single crystals as well as powders of 2,2,5,5‐tetramethylpyrrolidine‐3‐carboxamide‐1‐oxyl have been observed. Possible reasons of this fact are proposed. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Study on the metastable zone width of ketoprofen
Authors: Lu Ying Hong , Ching Chi Bun
Published: March 2006

With increasing awareness for the need of pure enantiomer drugs, strong emphasis has been focused on the research of chiral drug separation. Compared with other separation methods, crystallization is a simple and economical method, and the metastable zone width (MSZW) is a very important factor for the entire crystallization process. In this paper, the effects of the metastable zones of (R,S)‐ and (S)‐ketoprofen and a 0.94 mole fraction of (S)‐ketoprofen in order to enhance the MSZW were studied. Four main factors were studied, namely, temperature, cooling rate, stirring rate, and volume ratio of mixed solvent (water/ethanol). Through the L9 fractional experiment design, it was observed that all samples' MSZWs would increase with an increase in cooling rate and decrease with an increase in the ethanol volume ratio and temperature. The ethanol ratio may have the strongest effect on the process and can greatly enhance the metastable zone, and the other three factors influence the MSZW only slightly. In conclusion, the these four factors for enhancing MSZW have been optimized: water‐to‐ethanol volume ratio, 1:0.6; temperature, 20°C; stirring rate, 700 rpm; and cooling rate, 12.0°C/h. All of these results will be helpful for the following chiral separation of ketoprofen by crystallization. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
MARCO, an innate activation marker of macrophages, is a class A scavenger receptor for Neisseria meningitidis
Authors: Mukhopadhyay Subhankar , Chen Yunying , Sankala Marko , Peiser Leanne , Pikkarainen Timo , Kraal Georg , Tryggvason Karl , Gordon Siamon
Published: March 2006

The scavenger receptor‐A I/II (SR‐A) and macrophage receptor with collagenous domain (MARCO) share a common domain organisation and ligand repertoire, including selected polyanions and gram‐positive and ‐negative organisms, but differ in fine specificity of ligand binding, tissue distribution and regulation. Neisseria meningitidis (NM) is a selective ligand for SR‐A, but there is evidence for an additional SR‐A‐independent, polyanion‐sensitive component for NM recognition. We therefore studied the relative contribution of MARCO and SR‐A to binding of NM by resident and elicited peritoneal macrophages obtained from MARCO–/–, SR‐A–/– and SR‐A‐MARCO–/– mice. Results confirmed that both mouse and human MARCO are able to bind NM independently of NM LPS. MARCO and SR‐A contributed independently to NM binding, correlating with their expression levels in different cell populations, but neither of these two molecules was required for release of TNF‐α and nitric oxide. We propose that the TLR‐dependent induction of MARCO by innate immune stimulation enhances recognition and uptake of pathogenic organisms such as NM, thus contributing to host defence against infection.
Therapeutic potential of self‐antigen‐specific CD4+CD25+ regulatory T cells selected in vitro from a polyclonal repertoire
Authors: Fisson Sylvain , Djelti Fathia , Trenado Aurélie , Billiard Fabienne , Liblau Roland , Klatzmann David , Cohen José L. , Salomon Benoît L.
Published: March 2006

CD4+CD25+ regulatory T cells (Treg) play a major role in the prevention of autoimmune diseases. Converging evidence indicates that Treg specific for self‐antigens expressed by target tissues have a greater therapeutic potential than polyclonal Treg. Therefore, the selective expansion of rare self‐antigen‐specific Treg naturally present in a polyclonal repertoire of Treg is of major importance. In this work, we investigated the potential of different dendritic cell (DC) subsets to expand antigen‐specific Treg in mice. The in vitro selective expansion of rare islet‐specific Treg from polyclonal Treg could only be achieved efficiently by stimulation with CD8+ splenic DC presenting islet antigens. These islet‐specific Treg exerted potent bystander suppression on diabetogenic T cells and prevented type 1 diabetes. This approach opens new perspectives for cell therapy of autoimmune diseases.

See accompanying commentary: http://dx.doi.org/10.1002/eji.200635967
Dendritic cells modified to express fractalkine/CX3CL1 in the treatment of preexisting tumors
Authors: Nukiwa Mio , Andarini Sita , Zaini Jamal , Xin Hong , Kanehira Masahiko , Suzuki Takuji , Fukuhara Tatsuro , Mizuguchi Hiroyuki , Hayakawa Takao , Saijo Yasuo , Nukiwa Toshihiro , Kikuchi Toshiaki
Published: March 2006

Fractalkine (CX3CL1) is a unique membrane‐bound CX3C chemokine that serves as a potent chemoattractant for lymphocytes. The hypothesis of this study is that dendritic cells (DC) genetically modifiedex vivoto overexpress fractalkine would enhance the T cell‐mediated cellular immune response with a consequent induction of anti‐tumor immunity to suppress tumor growth. To prove this hypothesis, established tumors of different mouse cancer cells (B16‐F10 melanoma, H‐2b, and Colon‐26 colon adenocarcinoma, H‐2d) were treated with intratumoral injection of bone marrow‐derived DC that had been modifiedin vitrowith an RGD fiber‐mutant adenovirus vector expressing mouse fractalkine (Ad‐FKN). In both tumor models tested, treatment of tumor‐bearing mice with Ad‐FKN‐transduced DC gave rise to a significant suppression of tumor growth along with survival advantages in the treated mice. Immunohistochemical analysis of tumors treated with direct injection of Ad‐FKN‐transduced DC demonstrated that the treatment prompted CD8+T cells and CD4+T cells to accumulate in the tumor milieu, leading to activation of immune‐relevant processes. Consistent with the finding, the intratumoral administration of Ad‐FKN‐transduced DC evoked tumor‐specific cytotoxic T lymphocytes, which ensued fromin vivopriming of Th1 immune responses in the treated host. In addition, the anti‐tumor effect provided by intratumoral injection of Ad‐FKN‐transduced DC was completely abrogated in CD4+T cell‐deficient mice as well as in CD8+T cell‐deficient mice. These results support the concept that genetic modification of DC with a recombinant fractalkine adenovirus vector may be a useful strategy for cancer immunotherapy protocols.
Cross‐linking tumor cells with effector cells via CD55 with a bispecific mAb induces β‐glucan‐dependent CR3‐dependent cellular cytotoxicity
Authors: Gelderman Kyra A. , Lam Suzanne , Sier Cornelis F. , Gorter Arko
Published: March 2006

Complement (C) regulatory proteins decrease the effectiveness of immunotherapeutic anti‐cancer antibodies. Bispecific mAb (bi‐mAb) that target a tumor antigen and simultaneously inhibit a C regulator increase the effectiveness of such a therapy. Here we investigated the mechanism by which bi‐mAb increase tumor cell lysis. Apart from C‐dependent cytotoxicity, C activation can lead to complement receptor 3 (CR3)‐dependent cellular cytotoxicity (CR3‐DCC) by CR3‐positive effector cells in the presence of β‐glucan. Here we show that an anti‐Ep‐CAM*anti‐CD55 bi‐mAb induced more than threefold higher CR3‐DCC (71%) of human colorectal cancer cells compared with anti‐Ep‐CAM alone (20%). This CR3‐DCC was dependent on the binding of the anti‐CD55 arm of tumor‐bound anti‐Ep‐CAM*anti‐CD55 bi‐mAb to effector cell CD55, CR3 priming by β‐glucan and the presence of iC3b on the target cell. Comparable lysis could be obtained in the absence of iC3b, when CR3 and CD55 were cross‐linked on the effector cells, suggesting cooperation between CD55 and CR3 in signal transduction. Tumor cells with low antigen expression were effectively lysed via this mechanism in contrast to direct C‐dependent cytotoxicity. These data imply that the effectiveness of mAb immunotherapy can be improved using anti‐tumor antigen*anti‐CD55 bi‐mAb and β‐glucan, thereby initiating CR3‐DCC as an additional effector mechanism that is efficient for eradication of tumor cells with lower antigen expression.
Comparison of different CpG oligodeoxynucleotide classes for their capability to stimulate human NK cells
Authors: Sivori Simona , Carlomagno Simona , Moretta Lorenzo , Moretta Alessandro
Published: March 2006

Oligodeoxynucleotides (ODN) containing unmethylated CpG dinucleotides (CpG ODN) mimic the immunostimulatory activity of microbial DNA via Toll‐like receptor (TLR)9. Previous studies indicated that human NK cells express functional TLR3 and TLR9, since their cytokine release and cytolytic function could be incremented by poly(I:C) or ODN A/B, respectively. We have now evaluated the capability of a novel class of CpG ODN, termed ODN C, to modulate the function of human NK cells in the presence of exogenous cytokines. We show that NK cells isolated from peripheral blood and cultured with ODN C, in the presence of either IL‐12 or IL‐8, express higher levels of CD69 as compared to those stimulated with either ODN A or ODN B. Moreover, NK cells cultured with ODN C displayed higher cytolytic activity against tumor cell lines. These effects were not confined to freshly isolated peripheral blood NK cells since polyclonal NK cell populations that had been cultured in the presence of exogenous IL‐2 for several weeks also displayed higher cytolytic activity and cytokine release after culture in the presence of ODN C. Remarkably, NK cells displaying poor responses to ODN A/B were efficiently stimulated by ODN C.
Electronic Characterisation and Significant Second‐Order NLO Response of 10,20‐Diphenylporphyrins and Their ZnII Complexes Substituted in the meso Position with π‐Delocalised Linkers Carrying Push or Pull Groups
Authors: Morotti Tamara , Pizzotti Maddalena , Ugo Renato , Quici Silvio , Bruschi Maurizio , Mussini Patrizia , Righetto Stefania
Published: March 2006

This work describes the synthesis and the electronic characterisation by electronic absorption spectroscopy, cyclic voltammetry and dipole moments of diphenyl porphyrins and their ZnII complexes substituted at the meso position by a pseudo‐linear π‐delocalised substituent carrying an electron‐donor or an electron‐withdrawing group. The second‐order NLO response was investigated by the EFISH technique working with a nonresonant incident wavelength of 1.907 μm. This work confirms the ambivalent role of the polarisable porphyrin ring, which, already in the ground state, acts as a donor or acceptor depending on the nature (acceptor or donor) of the substituent in the meso position, as was pointed out in our previous work on tetraphenyl porphyrins substituted at the β‐pyrrolic position. The second‐order NLO response has been discussed by comparing the nature of the substituent (electron donor or acceptor) and the kind of substitution (β pyrrolic or meso). This comparison evidenced a significant increase of the electron‐donor properties of NBu2 or NMe2 when they are connected to the meso position or to the β‐pyrrolic position, probably because of an auxiliary donor effect of the electron‐rich porphyrin ring. When the substituent is the electron‐withdrawing NO2 group, the substituent position (meso or β pyrrolic) is influential, with the existance of a significant increase in the second order NLO response when substitution occurs at the meso position. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Dipolar Organoiron Pyranylideneacetaldehyde Hydrazone Complexes: Synthesis, Characterization, Crystal Structure, Linear and Nonlinear Optical Properties (Eur. J. Inorg. Chem. 6/2006)
Authors: Millán Lorena , Fuentealba Mauricio , Manzur Carolina , Carrillo David , Faux Nadèege , Caro Bertrand , Robin‐Le Guen Françoise , Sinbandhit Sourisak , Ledoux‐Rak Isabelle , Hamon Jean‐René
Published: March 2006

The cover picture shows the crystal structure of the cationic organometallic κ‐conjugated push–pull chromophore combining the mixed sandwich acceptor group [CpFe(η6‐p‐MeC6H4)]+, associated with the 2‐tert‐butyl‐4H‐chromen‐4‐ylidene donor through the asymmetric hydrazone spacer –NH–N=CH–. This dipolar chromophore exhibits solvatochromic properties, low‐lying intramolecular charge‐transfer transition and enhanced second‐order NLO properties (μβ), as measured with the EFISH technique at 1.907 μm. The scientific cooperation between researchers from the Southern Hemisphere (Chile) and the Northern Hemisphere (France) is symbolised not only by the Southern Cross but also by the NaCl crystals of the salt desert El Salar de Atacama. Details are discussed in the article by C. Manzur, D. Carrillo, B. Caro, J.‐R. Hamon et al. on p. 1131 ff.
Deodorization of lipase‐interesterified butterfat and rapeseed oil blends in a pilot deodorizer
Authors: Rønne Torben H. , Jacobsen Charlotte , Xu Xuebing
Published: March 2006

A mixture of butterfat and rapeseed oil (7 : 3, wt/wt) was interesterified using immobilized lipase from Thermomyces lanuginosus at 50 °C. The interesterified mixture was then deodorized at five temperatures (60–180 °C) and three samples were withdrawn at 1, 2, and 3 h. The operation was monitored by free fatty acid (FFA) content, peroxide value (PV), volatiles, and the sensory evaluation of the samples with respect to flavor and odor (most importantly the butter flavor and odor and the off‐flavor and odor from butyric acid). ANOVA partial least squares regression analysis showed that deodorization time, and especially deodorization temperature, significantly affected the sensory properties and levels of volatiles, FFA and peroxides in the samples. The best compromise between removing undesirable off‐flavors while maintaining the desirable butter flavor seemed to be obtained by using a deodorization temperature of 120 °C for 2 h. Response surface methodology analysis showed a significant effect of deodorization temperature and, to a lesser extent, deodorization time. The butter flavor and odor had an optimum at a deodorization temperature of approximately 100–120 °C for 1–2 h. These conditions are therefore recommended in order to remove the off‐flavor and odor, while maintaining as much as possible of the attractive butter flavor and odor.
Storage stability of margarines produced from enzymatically interesterified fats compared to those prepared by conventional methods – Chemical properties
Authors: Zhang Hong , Jacobsen Charlotte , Pedersen Lars Saaby , Christensen Morten Würtz , Adler‐Nissen Jens
Published: March 2006

In this study, four margarine hardstocks were produced, two from enzymatically interesterified fats at 80 and 100% conversion, one from chemically randomized fat and one from physically mixed fat. These four hardstocks, blended with 50% sunflower oil, were mainly used for the production of table margarines in a pilot plant. Storage stability studies were carried out at storage temperatures of 5 and 25 °C for 12 wk. Margarines from the enzymatically interesterified fats were compared to the margarines produced by the conventional methods (chemical interesterification and physical blending) and to selected commercial margarines. The changes in the chemical properties of the products, including peroxide values (PV), tocopherols, free fatty acids, volatile oxidation products, and sensory evaluation, were examined during storage. It was observed that the margarine produced from the chemically interesterified fat had higher PV in weeks 4, 8 and 10 than the margarines produced from the enzymatically interesterified fats and the physically blended fat. These differences were not caused by different contents of tocopherols in the hardstocks. The differences between the processes for chemical and enzymatic interesterification, including further treatment stages, might be responsible for the development of a high PV in the margarine produced from the chemically interesterified fat. However, the contents of volatiles did not show the same tendency as observed for PV for the margarines stored at 25 °C during 12 wk. Storage at 25 °C accelerated oxidation compared to storage at 5 °C. The content of δ‐ and γ‐tocopherols decreased faster than the content of α‐ and β‐tocopherols during storage. This phenomenon was only affected by storage time, not by storage temperature. Sensory analysis did not show consistent differences between the produced margarines and commercial margarines, and no hydrolysis occurred for these four margarines during storage. The margarines produced from the enzymatically interesterified fats had low PV and a similar taste and smell compared to the margarine produced from the chemically interesterified fat.
Tetrathiafulvalene‐Based Podands for Pb2+ Recognition
Authors: Lyskawa Joël , Le Derf Franck , Levillain Eric , Mazari Miloud , Sallé Marc
Published: March 2006

The synthesis and design optimization of a series of new redox‐reponsive ligands built around the tetrathiafulvalene electroactive core and incorporating two to four pendant polyether binding sites are described. A comparative study of the recognition properties of these podand‐TTFs forlead(II) has been carried out by cyclic voltammetry. The design optimization produced a ligand (1c) that exhibits a remarkably high affinity for lead(II), as shown by electronic absorption spectroscopy, 1H NMR titration studies and cyclic voltammetry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
An Efficient Synthesis of 2‐Bromo‐3‐hydroxy Esters by Reaction of Ketones with Ethyl Dibromoacetate Promoted by Samarium Diiodide
Authors: Concellón José M. , Concellón Carmen , Diaz Pamela
Published: March 2006

A simple and efficient samarium diiodide mediated synthesis of 2‐bromo‐3‐hydroxy esters 1 by the reaction of a variety of ketones 2 with ethyl dibromoacetate (3) is described. The relative configuration of the major diastereoisomer obtained was established by NOESY experiments of the corresponding α,β‐epoxy esters 4 prepared from 1. Additionally, a mechanism is proposed to explain the results obtained. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Functionalized 1‐Alkoxy‐1,3‐dienes: Their Preparation and Applications in Synthetic Organic Chemistry
Authors: Deagostino Annamaria , Prandi Cristina , Zavattaro Chiara , Venturello Paolo
Published: March 2006

The reaction of various α,β‐unsaturated acetals with two equivalents of the Schlosser reagent LIC‐KOR [equimolar mixture of BuLi (LIC), and tBuOK (KOR)] gives 1‐metalated (1E)‐1‐alkoxy‐1,3‐dienes. These products can be transformed into trienic derivatives that are apt to participate in intramolecular Diels–Alder (IMDA) cycloaddition reactions, and can also be transformed into bifunctional (γ‐halo‐α‐carbonyl) reagents. Moreover, the metalated dienes can be readily functionalized with suitable electrophiles to afford products that have been found to be useful reagents for the Stille and Suzuki cross‐coupling reactions or arylated according to the conditions of the Heck process. Other significant syntheses of dienic and polyenic structures are reported along with some of their applications in organic synthesis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Dediazoniation of 4‐Nitrobenzenediazonium Ions in Acidic MeOH/H2O Mixtures: Role of Acidity and MeOH Concentration on the Formation of Transient Diazo Ethers that Initiate Homolytic Dediazoniation
Authors: Pazo‐Llorente Roman , Maskill Howard , Bravo‐Diaz Carlos , Gonzalez‐Romero Elisa
Published: March 2006

We have investigated the dediazoniation of 4‐nitrobenzenediazonium (4NBD) ions in MeOH/H2O mixtures under acidic conditions at 50 °C employing a combination of spectrophotometric and chromatographic techniques. The kinetic behaviour is quite complex; in the absence of MeOH, the dediazoniations follow first‐order kinetics with a half‐life t1/2 = 1383 min, but the addition of small concentrations of MeOH lead to more rapid but non‐first‐order kinetics, suggestive of a radical mechanism, with t1/2 ≈ 6 min at 10 % MeOH. Further increases in the MeOH concentration slow down the rate of dediazoniation and reactions progressively revert to first‐order behaviour, with clean first‐order kinetics at percentages of MeOH higher than 90 % (t1/2 ≈ 77 min). The analyses of the reaction mixtures by HPLC indicate up to four dediazoniation products depending on the particular experimental conditions. These are 4‐nitrophenol (ArOH), 4‐nitroanisole (ArOMe), nitrobenzene (ArH), and 4,4′‐dinitrobiphenyl (DNB), this last product being detected only at MeOH percentages in the range 0.5–15 %. In the absence of MeOH, ArOH is the only product and formed in quantitative yield; however, at only 20 % MeOH, ArOH is down to less than 10 % and the reduction product, ArH, is obtained in more than 90 %. Upon increasing the MeOH content further, the formation of ArOMe becomes competitive and, at 99 % MeOH, both ArH (60 %) and ArOMe (40 %) are obtained. The observed rate constants, kobsd., or half‐lives, t1/2, are the same regardless of whether they are determined by monitoring product formation (by a well‐established product derivatization protocol followed by HPLC measurements) or reactant decomposition (obtained UV spectrophotometrically). At any given MeOH content, the plot of kobsd. or t1/2 values against the acidity (defined as –log [HCl]) is S‐shaped, the inflexion point depending upon the MeOH concentration. The complex behaviour can be accounted for by two competitive mechanisms, and whichever is dominant depends upon the acidity and the composition of the aqueous methanol solvent. Furthermore, the acid‐dependence of the switch between the homolytic and heterolytic mechanisms suggests the homolytic dediazoniation proceeds via transient diazo ethers. Thus, the MeOH molecules react with ArN2+ to yield an O‐coupling adduct in a highly unstable Z configuration, i.e. a (Z)‐diazo ether. Subsequently, this undergoes homolytic fragmentation which initiates a radical process. In the polar alternative, the methanol simply solvates the ArN2+ ions, allowing them to undergo thermal heterolysis, i.e. a DN + AN mechanism via the aryl cation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Enantioselective Butenolide Preparation for Straightforward Asymmetric Syntheses of γ‐Lactones – Paraconic Acids, Avenaciolide, and Hydroxylated Eleutherol
Authors: Braukmüller Stefan , Brückner Reinhard
Published: March 2006

The naturally occurring γ‐lactones (+)‐methylenolactocin (13) and its enantiomer, (+)‐protolichesterinic acid (14) and its enantiomer, (+)‐rocellaric acid (15), and the methylene bis(γ‐lactone) (–)‐avenaciolide (16) were synthesized with 95–98 % ees in very few steps. Enantiocontrol was imposed by the asymmetric dihydroxylation of trans‐configured β,γ‐unsaturated carboxylic esters (namely compounds 1i, 1j, and 1n) with AD mix‐α® [for the levorotatory target structures, except for (–)‐avenaciolide] or AD mix‐β® [for the dextrorotatory target structures plus (–)‐avenaciolide]. β,γ‐Unsaturated carboxylic ester 1e required increased amounts of the oxidant and auxiliary to produce the hydroxy lactone R,R‐3e, a precursor of the naphtho‐γ‐lactone (+)‐9‐hydroxyeleutherol (12; 96 % ee). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Complex Formation in the Region of Metal Hydrolysis and M(OH)2 Precipitation. A Glass Electrode Potentiometric and Polarographic Study of Cd–(AMPSO)x–(OH)y and Zn–(AMPSO)x–(OH)y Systems
Authors: Machado Carina M. M. , Cukrowski Ignacy , Soares Helena M. V. M.
Published: March 2006

The interaction between cadmium or zinc and AMPSO was investigated by DCP and GEP, at fixed total ligand to total metal concentration ratios and various pH values, at 25.0 °C and 0.1 M KNO3 ionic strength. For Cd–(AMPSO)x–(OH)y system, CdL and CdL(OH) species, were identified, with stability constants values set to (as log β): 2.1±0.1 and 6.2±0.2, respectively. For Zn–(AMPSO)x–(OH)y system, the proposed final model with stability constants set to (as log β) is: ZnL=2.5±0.1 and ZnL(OH)2=12.9±0.2. For both systems, the fact that AMPSO deprotonation occurs in the metal hydrolysis and M(OH)2 precipitation and the complexes formed are not too strong added a real challenge to data interpretation.
Ascorbic Acid Oxidation at Nonmodified and Copper‐Modified Polyaniline and Poly‐ortho‐methoxyaniline Coated Electrodes
Authors: Komsiyska Lidiya , Tsakova Vessela
Published: March 2006

The electrochemical oxidation of ascorbate ions is comparatively studied at polyaniline (PANI) and poly‐ortho‐methoxyaniline (POMA) layers in absence and presence of electrodeposited copper species. In comparison to PANI, POMA layers allow decreasing the overpotential necessary for driving the ascorbate oxidation reaction. A nonlinear dependence of the ascorbate oxidation current on the polymer layer redox charge is found. Copper electrodeposited in PANI and POMA layers is electrocatalytically active for the investigated reaction. Two separate oxidation waves are observed in the case of Cu‐PANI whereas a single ascorbate oxidation wave and enhanced currents are found in the Cu‐POMA case.
A comparison of machine‐learning classifiers for selecting money managers
Authors: Ludwig Robert S. , Piovoso Michael J.
Published: March 2006

Machine‐learning algorithms have performed well on noisy datasets that are typical of financial data. This paper compares the performance of three types of machine‐learning classifier for selecting money managers. Naïve Bayes, neural network and decision tree learners were applied to a dataset of US equity managers. Although other studies have suggested that the performance of classifiers appears to be highly dependent on the nature of the problem and the dataset, the learning algorithms each had similar predictive accuracy and all outperformed by a substantial margin simple manager selection rules that are typical of the ways in which money managers and mutual funds are selected by investors. The results indicate that machine learners can be used as a decision‐support aid to improve the selection of money managers. Copyright © 2005 John Wiley & Sons, Ltd.
Estimating the effect of smoking on birth outcomes using a matched panel data approach
Authors: Abrevaya Jason
Published: March 2006

Estimating the casual effect of smoking on birth outcomes is difficult since omitted (unobserved) variables are likely to be correlated with a mother's decision to smoke. While some previous work has dealt with this endogeneity problem by using instrumental variables, this paper instead attempts to estimate the smoking effect from panel data (i.e., data on mothers with multiple births). Panel data sets are constructed with matching algorithms applied to federal natality data. The fixed effects regressions, which control for individual heterogeneity, yield significantly different results from ordinary least squares and previous instrumental variable approaches. The potential inconsistency caused by ‘false matches’ and other violations of the fixed effects strict exogeneity assumption are considered. Copyright © 2006 John Wiley & Sons, Ltd.
Tests of seasonal integration and cointegration in multivariate unobserved component models
Authors: Busetti Fabio
Published: March 2006

This paper considers tests of seasonal integration and cointegration for multivariate unobserved component models. First, the locally best invariant (LBI) test of the null hypothesis of a deterministic seasonal pattern against the alternative of seasonal integration is derived for a model with Gaussian i.i.d. disturbances and deterministic trend. Then the null hypothesis of seasonal cointegration is considered and a test for common nonstationary components at the seasonal frequencies is proposed. The tests are subsequently generalized to account for stochastic trends, weakly dependent errors and unattended unit roots. Asymptotic representations and critical values of the tests are provided, while the finite sample performance is evaluated by Monte Carlo simulation experiments. Finally, the tests are applied to the series of industrial production of the four largest countries of the European Monetary Union. It is found that Germany does not appear to cointegrate with the other countries at most seasonal frequencies, while there seems to exist a common nonstationary seasonal component between France, Italy and Spain. Copyright © 2006 John Wiley & Sons, Ltd.
Sintering‐induced aromatization during n‐heptane reforming on Pt/Al2O3 catalysts
Authors: Susu Alfred A , Ogogo Emmanuel O
Published: March 2006

A platinum/alumina catalyst was sintered in oxygen and hydrogen atmospheres using two metal loadings of the catalyst: 0.3% Pt and 0.6% Pt. After sintering, the aromatization selectivity was investigated with the reforming of n‐heptane as the model reaction at a temperature of 500 °C and a pressure of 391.8 kPa. The primary products of n‐heptane reforming on the fresh platinum catalysts were methane and toluene, with subsequent conversion of benzene from toluene demethylation. To induce sintering, the catalysts were treated with oxygen at a flow rate of 60 mL min−1, pressure of 195.9 kPa and temperatures between 500 and 800 °C. The 0.3% Pt/Al2O3 catalyst exhibited enhanced aromatization selectivity at various sintering temperatures while the 0.6% Pt/Al2O3 catalyst was inherently hydrogenolytic. The fact that aromatization was absent on the 0.6% Pt/Al2O3 catalyst was attributed to the presence of surface structures with dimensionality between two and three as opposed to essentially 2‐D structures on the 0.3% Pt/Al2O3 catalyst surface. On the 0.3% Pt/Al2O3 catalyst, the reaction product ranged from only toluene at a 500 °C sintering temperature to predominantly cracked product at a sintering temperature of 650 °C and no reaction at 800 °C. For sintering at about 650 °C, subsequent conversion of n‐heptane was complete and dropped thereafter. The turnover number was observed to change from 0.07 to 2.26 s−1 as the dispersion changed from 0.33 to 0.09. The Koros–Nowark (K–N) test was used to check for the presence of internal diffusional incursions and Boudart's criterion was used for structural sensitivity determination. The K–N test indicated the absence of diffusional resistances while n‐heptane reforming was found to be structure sensitive on the Pt/Al2O3 catalyst. Copyright © 2006 Society of Chemical Industry
Effects of gas flow‐rate and inlet concentration on nitric oxide removal in an autotrophic biofilter
Authors: Chen Jianmeng , Wang Jiade , Ma Jianfeng
Published: March 2006

The effects of inlet gas concentration and gas flow‐rate on the NO elimination process were studied in a laboratory‐scale biofilter and the removal process is discussed. Various pollutant inlet concentrations and gas flow‐rates were tested in the biofilter. The results showed that the removal efficiency increased with increase in the empty bed residence time (EBRT) and finally reached a steady state. The mass transfer process became the limiting step of NO removal when the EBRT was less than 2 min. A removal efficiency of ∼73% was obtained in the biofilter at an inlet concentration of 107.1 mg m−3. The removal efficiency decreased with increase in inlet concentration, whereas the removal capacity increased. The removal process consisted of chemical oxidation and bio‐nitrification in the biofilter. The bioprocess mainly contributed to the removal. Copyright © 2006 Society of Chemical Industry
Optimised immobilisation of microbial lipase on hydrous niobium oxide
Authors: Miranda Michele , da Silva M Lúcia CP , de Castro Heizir F
Published: March 2006

The aim of this work was to establish appropriate conditions for immobilising Candida rugosa lipase on a low‐cost inorganic matrix, hydrous niobium oxide, using a multivariate statistical approach. A 23 full factorial design was employed to determine the effects of support activation with glutaraldehyde (concentration 2.5–4.5%, pH 7–10) and lipase loading (200‐700 U g−1 matrix) on the hydrolytic and synthetic activities of the immobilised derivatives. From the results the following conditions were established: lipase loading of 450 U g−1 matrix and niobium oxide activation with glutaraldehyde at a concentration of 2.5% and pH 8. Under these conditions, high activity recovery (47.21%) and esterification yield (86.90%) were attained. The results also show that hydrous niobium oxide can be a valid alternative to replace high‐cost, commercially available inorganic matrices such as controlled pore silica. Copyright © 2006 Society of Chemical Industry
Treatment of PAH‐contaminated soil by combination of Fenton's reaction and biodegradation
Authors: Palmroth Marja RT , Langwaldt Jörg H , Aunola Tuomo A , Goi Anna , Puhakka Jaakko A , Tuhkanen Tuula A
Published: March 2006

A combination of modified Fenton and biological treatment was used to remove polycyclic aromatic hydrocarbons (PAHs) from creosote oil‐contaminated soil. After modified Fenton reaction the toxicity of column leachate and soil to Vibrio fischeri increased. The number of intact bacterial cells and utilisation of PAHs in PAH utilisation microplate assay decreased after modified Fenton reaction. However, bacteria in chemically treated soil utilised PAHs without addition of other carbon sources. The activity of extracellular esterases increased during incubation of modified Fenton‐treated soil. PAH removal in combined chemical oxidation and incubation (43–59%) was higher than in incubation alone (22–30%). Residual H2O2 in soil allowed chemical oxidation of PAHs during incubation. Copyright © 2006 Society of Chemical Industry
Improving lipase production using a perfluorocarbon as oxygen carrier
Authors: Amaral Priscilla FF , Rocha‐Leão Maria Helena M , Marrucho Isabel M , Coutinho João AP , Coelho Maria Alice Z
Published: March 2006

Perfluorodecalin, a perfluorocarbon (PFC), was used as an oxygen vector in culture media to enhance lipase productivity by increasing the oxygen availability to Yarrowia lipolytica. The effects of different concentrations of PFC were studied in shake‐flask yeast cultures at 160 and 250 rpm. Higher specific growth rates of Y. lipolytica were found with increasing PFC concentration and agitation rate. Lipase production by Y. lipolytica was enhanced 23‐fold with the addition of 20% (v/v) PFC at 250 rpm. Moreover, it is shown that using PFC and glucose as substrate is more effective in lipase production than the conventional use of olive oil. Copyright © 2006 Society of Chemical Industry
Direct extraction of phenylacetic acid from immobilised enzymatic hydrolysis of penicillin G with cloud point extraction
Authors: Wang Zhilong , Guo Yajing , Bao Da , Qi Hanshi
Published: March 2006

The enzymatic hydrolysis of potassium salt of penicillin G (Pen G) into phenylacetic acid (PAA) and potassium salt of 6‐aminopenicillanic acid (APA) is inhibited not only by the substrate and the product APA but also by the by‐product PAA. The partitioning behaviour of PAA in a cloud point system, a novel two‐phase partitioning system, was determined. Direct extraction of PAA in the process of immobilised penicillin acylase hydrolysis of Pen G without pH control was achieved. Pen G was hydrolysed almost completely and the product APA concentration in the cloud point system was much higher than in the control, suggesting that the cloud point system may be applied as a novel extractive bioreactor for the enzymatic hydrolysis of Pen G. Copyright © 2006 Society of Chemical Industry
Cellular mechanism of estrogen‐induced thymic involution in wall lizard: caspase‐dependent action
Authors: Hareramadas Batchu , Rai Umesh
Published: March 2006

The present study, for the first time in an ectothermic vertebrate, demonstrates the cellular mechanism of estrogen‐induced thymic involution. Ovariectomy in lizards during the preparatory phase of the reproductive cycle resulted in distinct differentiation of cortico‐medullary regions and increase in cellularity, especially in the cortical region. The ovariectomy‐induced changes were reversed following administration of 17β‐estradiol (E2), suggesting a primary role of E2 in causing thymic atrophy. To understand the cellular mechanism of E2‐induced thymic atrophy, in vitro effect of E2 was investigated on thymocyte proliferation and apoptosis. E2 decreased the uptake of tritiated thymidine (3H‐TdR) by thymocytes in a dose‐dependent manner, suggesting that estrogen directly inhibits the thymocyte proliferation. Unlike proliferation, E2 did not have any direct effect on thymocyte apoptosis, as evident by DNA gel electrophoretic, flow cytometric or fluorescence microscopic studies. However, in the presence of thymic epithelial cell‐rich stromal components (TEC), E2 treatment at low or high concentrations resulted in depolarization of plasma membrane, DNA fragmentation and decrease in DNA content. This suggests that E2 indirectly, through TEC‐secreted factors, controls thymocyte apoptosis. Similar result was observed following fluorescence microscopy. The indirect effect of E2 was further ascertained with the findings that E2‐pretreated TEC‐conditioned medium accelerated the thymocyte apoptosis. Nevertheless, exposure of thymocytes to E2 was seen to be inevitable for the apoptotic action of TEC‐secreted paracrine factors. In the presence of TEC, a positive reaction for caspase‐3, ‐7 and ‐9 and enzyme substrate, poly(ADP‐ribose) polymerase (PARP) in response to E2 suggests the caspase‐dependent thymocyte apoptosis in the wall lizard Hemidactylus flaviviridis. Further, E2 was shown to act through genomic pathway, since the receptor antagonist tamoxifen and transcription/translation inhibitors blocked its apoptotic action. Interestingly, the apoptotic effect of E2 was effectively decreased by progesterone. J. Exp. Zool. 305A, 2006. © 2006 Wiley‐Liss, Inc.