bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Ring Size on Catenane Synthesis
Authors: Duda Stefan , Godt Adelheid
Published: August 2003

The synthesis of a [2]catenane with 87‐membered rings was improved and extended to [2]catenanes with 63‐ and 147‐membered rings. One of the key features is the carbonate linkage between phenols with tolane substituents in the 2‐ and 6‐positions, which serves as a covalent template for the geometrical arrangement of a macrocycle and a ring precursor. Subsequent cyclization of the threaded ring precursor gives the precatenane as the main product, and this is converted into the catenane by carbonate hydrolysis. As well as the precatenane, its dumbbell shaped isomer is formed in the cyclization step. From the known conformation of the templating carbonate moiety and the strong dependence of the ratio of precatenane and dumbbell on the ring size, the dumbbell's origin is attributed to the conformational flexibility of the large rings and not to geometrical ambiguity of the carbonate moiety. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Atroposelectivity of Reactions of Benzylic Metalated Thiobenzamides and Thionaphthamides
Authors: Ach David , Reboul Vincent , Metzner Patrick
Published: August 2003

N,N‐Dialkyl‐2‐methylbenzenecarbothioamides and naphthalenecarbothioamides were prepared by thionation of amides with Lawesson’s reagent under unusual conditions. Their axial chirality was evidenced. Benzylic deprotonation of thioamides bearing N,N‐diisopropyl groups with sec‐butyllithium was selective. The resulting anions were reacted with prochiral electrophiles (aromatic aldehydes, an unsaturated aldehyde or ketone, and an imine) to afford diastereomeric adducts (up to 88:12 dr). This is the first report on atroposelective C−C bond formation in the benzylic position of thioamides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Inside Protonation of 1,8‐Diazabicyclo[6.6.n]alka‐4,11‐diynes
Authors: Balalaie Saeed , Kunze Andreas , Gleiter Rolf , Rominger Frank , Geis Sibylle , Oeser Thomas
Published: August 2003

Protonation of 1,8‐diazabicyclo[6.6.3]heptadeca‐4,11‐diyne (4a), 1,8‐diazabicyclo[6.6.4]octa‐deca‐4,11‐diyne (4b), 1,8‐diazabicyclo[6.6.5]nonadeca‐4,11‐diyne (4c), and 1,8‐diazabicyclo[6.6.6]eicosa‐4,11‐diyne (4d) was achieved by treatment of 4a−4d with strong acids. Monoprotonation products were isolated in all cases, while for 4b and 4c diprotonation products were also obtained. X‐ray investigations show inside protonation for the mono‐ and diprotonation products. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Solid‐Phase Synthesis of a Phytoalexin Elicitor Pentasaccharide Using a 4‐Azido‐3‐chlorobenzyl Group as the Key for Temporary Protection and Catch‐and‐Release Purification
Authors: Egusa Kenji , Kusumoto Shoichi , Fukase Koichi
Published: August 2003

A phytoalexin elicitor pentasaccharide of the rice blast disease fungus, Pyricularia oryzae, was synthesized by a new route involving a solid‐phase method, in which a 4‐azido‐3‐chlorobenzyl (ClAzb) group was used for temporary protection of the hydroxy functions and catch‐and‐release purification. Thioglycosides possessing the ClAzb group were used as glycosyl donors and a macroporous polystyrene as a solid support. The saccharide chain was elongated by repeating a set of reactions: removal of the ClAzb group, glycosylation and capping of the unglycosylated hydroxy groups. Cleavage from the solid support by treatment with sodium methoxide afforded a crude pentasaccharide possessing the ClAzb group as a tag. The pentasaccharide was then purified by a catch‐and‐release procedure based on the specific reaction between the azido group and a solid‐supported phosphane. The final deprotection of all benzyl‐type protective groups gave the desired phytoalexin elicitor pentasaccharide 1 in overall 15% yield (from a solid‐supported monosaccharide 4, average yield of 81% for each of a total of nine steps). The characteristic peaks of the azido group in the infrared spectrum were also useful for monitoring reactions in the solid phase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Pyrrolo‐Tetrathiafulvalenes and Their Applications in Molecular and Supramolecular Chemistry (Eur. J. Org. Chem. 17/2003)
Authors: Jeppesen Jan O. , Becher Jan
Published: August 2003

The cover picture shows the molecular structure (center) of the parent pyrrolo‐tetrathiafulvalene, which has been incorporated into a number of molecular and supramolecular systems, such as cyclophanes (upper right), rotaxanes (lower right), porphyrins (lower left), and calixpyrroles (upper left). The synthesis and physical properties of the parent pyrrolo‐tetrathiafulvalenes, followed by a journey through their applications in macrocyclic, molecular, and supramolecular chemistry, are described in the Microreview by J. O. Jeppesen and J. Becher on p. 3245 ff.
A two‐dimensional proteome map of Shigella flexneri
Authors: Liao Xiang , Ying Tianyi , Wang Hengliang , Wang Jie , Shi Zhaoxing , Feng Erling , Wei Kaihua , Wang Yuelan , Zhang Xuemin , Huang Liuyu , Su Guofu , Huang Peitang
Published: August 2003

Shigella flexneri is a Gram‐negative facultatively intracellular pathogen responsible for bacillary dysentery in humans. In this study, extracellular proteins from the culture medium and whole cell proteins in cellular extracts of S. flexneri 2a strain 2457T were examined by two‐dimensional (2‐D) gel electrophoresis using immobilized pH gradient (IPG) technology. Proteins were identified by matrix‐assisted laser desorption/ionization‐mass spectrometry (MALDI‐MS) in combination with Mascot search program. In total, among the 488 proteins spots processed, 388 proteins were identified. The identified proteins represented 169 genes. By comparing results of Mascot search against databases of Escherichia coli and genomes of S. flexneri 2a, one S. flexneri‐specific protein was identified and one possible gap was found in 2457T genome sequences. Although this proteome map is still incomplete, it is already a useful reference for future studies involving pathogenicity, vaccine development, design of novel antibacterial drugs, etc. Proteome maps and a table of all identified proteins are available on the internet at www.proteomics.com.cn.
Dimorphic Alu element located between the TFIIH and CDSN genes within the major histocompatibility complex
Authors: Dunn David S. , Inoko Hiditoshi , Kulski Jerzy K.
Published: August 2003

Most Alu members of the large SINE family are fixed within the human genome but some younger mobile members are dimorphic, that is, they are either present or absent in the genome. Four different dimorphic Alu insertions have been identified and characterized previously within the class I region of the major histocompatibility complex (MHC). Here we report on (i) the identification and characterization of a new dimorphic Alu insertion, AluyTF, located between the transcription factor II H (TFIIH) and corneodesmosin (CDSN) genes within a region of the MHC that is telomeric of the human leukocyte antigen type B (HLA‐B) locus and centromeric of the HLA‐A locus, (ii) the haplotypic relationships between the AluyTF dimorphism and the HLA‐A and ‐B loci within a panel of 48 IHW cell‐lines representing at least 36 different HLA class I haplotypes, (iii) the AluyTF genotype, allele and haplotype frequencies present in the Australian caucasian and Japanese populations, and (iv) the frequency of association between the AluTF dimorphisms and HLA‐A and ‐B alleles in 108 Australian caucasians and 99 Japanese. The AluyTF insertion was present at 27% in the IHW cell lines, and the gene frequency was 0.107 and 0.083 in the Australian caucasian and Japanese population, respectively. The Alu haplotype frequencies constructed from four different dimorphic Alu loci including AluyTF within the MHC were not significantly different (p > 0.05) between the two populations. There were no significant associations between the Alu insertion and either the HLA‐A or ‐B alleles except for a moderately strong association with HLA‐A29 in the Australians (71.7%). This polymorphic AluyTF element, along with the four other previously described polymorphic Alu elements within the class I region of the MHC, will be useful lineage and linkage markers in human population studies and for elucidating the evolution of HLA class I haplotypes.
Capillary electrophoresis of trace metals in highly saline physiological sample matrices
Authors: Riaz Asif , Kim Bojeong , Chung Doo Soo
Published: August 2003

Trace metal ions in highly saline samples such as urine were determined with capillary electrophoresis (CE) without desalting or off‐line preconcentration. By mixing with a dye, 4‐(2‐pyridylazo) resorcinol (PAR), the metal ions were converted into anionic complexes having strong absorbance near 500 nm. A large volume of the metal‐PAR complex sample solution injected into a coated capillary was stacked isotachophoretically and separated under a reverse potential. The salt anion (chloride) and PAR in the sample matrix acted as the leading and terminating electrolytes, respectively. In a sample containing a 250 mM NaCl matrix, more than 400‐fold enhancement in the absorbance detector response was realized compared to the normal CE injection mode. Combination of the dye complexation and isotachophoretic stacking provided excellent detection limits (S/N = 3) for three trace metal ions in the low ppb range (Fe2+, 0.7 ppb, Ni2+, 0.4 ppb; Zn2+, 1.2 ppb) with absorbance detection. The migration time reproducibility was excellent (relative standard deviations: standard samples < 1%, urine samples ∼1%). The proposed method is convenient and fast, and the sample analysis can be completed within 20 min.
A simple polyacrylamide gel electrophoresis procedure for separation of polyamidoamine dendrimers
Authors: Sharma Ajit , Mohanty Dillip K. , Desai Ankur , Ali Riaz
Published: August 2003

A simple, inexpensive, and rapid electrophoresis technique was developed for use as a routine tool for evaluating purity of polyamidoamine (PAMAM) dendrimers. A variety of factors influencing migration of generations 0–7 dendrimers on nongradient polyacrylamide gels were evaluated. The low generation dendrimers were found to be very sensitive to diffusion during or after electrophoresis. The proposed method incorporates steps that minimize diffusion, in order to obtain improved resolution and sensitivity, especially for the lower‐molecular‐weight dendrimers. This was accomplished by inclusion of a dendrimer fixation step with glutaraldehyde and performing the electrophoresis separation, fixation, staining, and destaining at 4°C. PAMAM dendrimer separation was studied under basic and acidic conditions. Electrophoresis under acidic conditions gave increased resolution and sensitivity over separation at alkaline pH. Oligomers and trailing generations could be clearly separated and visualized under these conditions. The smallest PAMAM dendrimer, generation 0, was visible at 1.5 μg under the optimized acidic conditions. With slight modifications, this technique should be applicable to separation of other water‐soluble dendrimers.
Improving sensitivity by large‐volume sample stacking using the electroosmotic flow pump to analyze some nonsteroidal anti‐inflammatory drugs by capillary electrophoresis in water samples
Authors: Macià Alba , Borrull Francesc , Aguilar Carme , Calull Marta
Published: August 2003

Large‐volume sample stacking using the electroosmotic flow (EOF) pump (LVSEP) has been used to analyze some nonsteroidal anti‐inflammatory drugs (NSAIDs) in water samples. With methanol as the run buffer solvent to suppress the EOF, sensitivity was enhanced by 80–100‐fold. The sample for the analysis of real water sample was pretreated by solid‐phase extraction (SPE). When the method was based on off‐line SPE‐LVSEP‐CE, sensitivity improved by as much as 1000 times.
Thylakoid membrane at altered metabolic state: Challenging the forgotten realms of the proteome
Authors: Rexroth Sascha , Meyer zu Tittingdorf Jürgen M. W. , Krause Frank , Dencher Norbert A. , Seelert Holger
Published: August 2003

Analysis of the membrane integral proteome is mainly dependent on the ability of protein separation. Blue‐native polyacrylamide gel electrophoresis (BN‐PAGE) is a technique capable of efficient membrane protein separation, so far mainly applied to the mitochondrial oxidative phosphorylation machinery. Applying BN‐PAGE to the thylakoid membranes after mild solubilization with digitonin we succeeded in displaying the response of the green algae Chlamydomonas reinhardtii to altered culture conditions. In addition, by peptide mass fingerprinting and matrix assisted laser desorption/ionization‐mass spectrometry (MALDI‐MS) extremely hydrophobic subunits of the photosystem complexes with 5–11 transmembrane helices were identified, which could not be accessed by in‐gel digestion in previous studies.
Characterization and quantitation of mixtures of alkyl ether sulfates and carboxylic acids by capillary electrophoresis with indirect photometric detection
Authors: Bernabé‐Zafón Virginia , Ortega‐Gadea Silvia , Simó‐Alfonso Ernesto F. , Ramis‐Ramos Guillermo
Published: August 2003

The separation, characterization, and determination of mixtures of alkyl ether sulfates (AES) and fatty acids (C10‐C16) in background electrolytes (BGEs) containing acetonitrile (ACN)‐water mixtures is addressed. Due to inhibition of the ionization of the carboxylate groups, the migration time and the resolution between the fatty acids decreased when the water content of the BGE was reduced, but efficiency and resolution between the AES oligomers improved. The migration times increased and resolution improved by substituting 5% ACN by an equivalent amount of dioxane. A complete separation of the two surfactant classes, up to the AES oligomers with 8 ethylene oxide units (EOs) with respect to C10, with excellent resolution between the AES oligomers, while preserving a satisfactory resolution between the fatty acids, was achieved with a BGE containing 5 mM trimethoxybenzoic acid, 7 mM dipentylamine, 85% ACN, 5% dioxane, and 10% water. The two surfactant classes were increasingly resolved by further reducing the water content of the BGE. Thus, C2 (acetate) was resolved from the AES oligomers up to 7 EOs using 90% ACN and 5% dioxane, but the resolution between the heavier fatty acids was poor with this BGE. Identification of the AES oligomers was eased by the excellent regularity of the successive migration times; thus, within each AES subclass or series of oligomers with the same number of carbon atoms in the alkyl chain, the migration times decreased following a mild curve as the number of EOs increased. The way how the data obtained by indirect photometry (corrected peak areas that are proportional to the molar concentrations) should be managed to avoid systematic error when the calibration curve is constructed using an AES standard with an oligomer distribution different from that of the samples is discussed and equations are given. Decyl sulfate was successfully used as internal standard. The detection limits (S/N = 3) were of ca. 2 μM for individual AES oligomers.
Casein phosphoproteome: Identification of phosphoproteins by combined mass spectrometry and two‐dimensional gel electrophoresis
Authors: Mamone Gianfranco , Caira Simonetta , Garro Giuseppina , Nicolai Adalgisa , Ferranti Pasquale , Picariello Gianluca , Malorni Antonio , Chianese Lina , Addeo Francesco
Published: August 2003

We report a fast and easy‐to‐use procedure that combines polyacrylamide gel electrophoresis with matrix assisted laser desorption/ionization‐time of flight‐mass spectrometry (MALDI‐TOF) and nanoelectrospray‐tandem mass spectrometry (nES‐MS/MS) analysis for the identification of casein components and defined phosphorylated sites. This methodology ensured identification of more than 30 phosphorylated proteins, five β‐, fifteen αs1‐, ten αs2‐, and four κ‐casein (CN) components, including nonallelic, differently phosphorylated, and glycosylated forms. The sugar motif covalently bound to κ‐CN was identified as chains, trisaccharide GalNAc, Gal, NeuGc, and tetrasaccharide 1GalNAc, 1Gal, 2NeuGc. Also identified was a biantennary chain made up of both chains of trisaccharide 1GalNAc, 1Gal, 1NeuGc, and tetrasaccharide 1GalNAc, 1Gal, 2NeuGc moiety on a single κ‐CN component. The phosphate group on site Ser12 of tryptic peptide 8–22 of most phosphorylated αs1‐CN (11 phosphate groups) was localized and the oligosaccharide sequence of the main tryptic glycopeptides of two κ‐CN components was determined by means of MS/MS analysis.
DNA capillary electrophoresis using poly(vinyl alcohol). I. Inner capillary coating
Authors: Moritani Tohei , Yoon Kyunghwan , Rafailovich Miriam , Chu Benjamin
Published: August 2003

Two new methods of inner capillary coating with poly(vinyl alcohol) (PVAL) have been investigated and evaluated by performing DNA capillary electrophoresis (CE) using PVAL as a separation medium and by measuring the electroosmotic flow (EOF) mobility. The treatment of capillaries with a silanol‐group modified PVAL (PVAL‐Si) has been found to give good coating effects for improving the resolution of DNA CE and for reducing the EOF. This coating must be effectively achieved by combining the adsorptive property of PVAL chains onto silica with the reaction between the silanol groups of PVAL‐Si and the silica surface. The adsorption of PVAL onto silica has been observed by using atomic force microscopy (AFM) for PVAL‐Si as well as for a nonmodified PVAL as a control. The coating with PVAL that links to the capillary wall surface with more hydrolytically stable bonding, –Si‐C–, has been formed by performing the Grignard reaction, followed by in‐capillary polymerization of vinyl acetate (VAc) and hydrolysis. This coating has been found to be effective for improving the resolution of DNA CE and for reducing the EOF.
DNA capillary electrophoresis using poly(vinyl alcohol). II. Separation media
Authors: Moritani Tohei , Yoon Kyunghwan , Chu Benjamin
Published: August 2003

We represent the first extensive study on DNA capillary electrophoresis using various poly(vinyl alcohol) (PVAL)‐related polymers as separation media. As a separation medium, PVAL homopolymer has shown poor resolutions probably due to its very strong hydrogen‐bonding characteristics, resulting in extensive self‐aggregation. On the other hand, poly(vinyl alcohol‐co‐vinyl acetate) and poly(vinyl alcohol‐co‐1‐vinyl‐2‐pyrrolidone) (PVAL‐VP), both with a degree of polymerization of ∼3.0×103, have been found to give excellent electropherograms with good resolutions for the analysis of double‐stranded (ds)DNA. PVAL‐VP, with hydrolytic stability in high and low pH regions, has also yielded fair electropherograms for single‐stranded (ss)DNA under neutral and alkaline conditions, although further investigation is essential in order to increase the resolutions necessary for DNA sequencing analysis. The separations obtained under alkaline conditions have shown significantly shorter retention times, one‐third of that for the current commercial separation media, due to the higher ionization of phosphate groups in the DNA chains.
Proteomics of snake venoms from Elapidae and Viperidae families by multidimensional chromatographic methods
Authors: Nawarak Jiraporn , Sinchaikul Supachok , Wu Chi‐Yue , Liau Ming‐Yi , Phutrakul Suree , Chen Shui‐Tein
Published: August 2003

Snake venoms contain a large number of biologically active substances and the venom components are very useful for pharmaceutical applications. Our goal is to separate and identify components of snake venoms in ten snake species from the Elapidae and Viperidae families using multidimensional chromatographic methods. The multidimensional chromatographic methods include reversed‐phase high‐performance liquid chromatography (RP‐HPLC), sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), lab‐on‐a‐chip, two‐dimensional electrophoresis (2‐DE), and mass spectrometry. The venoms of eight snake species demonstrated major differences in hydrophobicity, molecular weight separations, and 2‐DE protein distribution patterns. The 2‐DE images showed major differences between families, within each family and even between the same species. Venoms of the Elapidae family showed many basic proteins with a wide range of molecular weights, while venoms of the Viperidae family showed wide ranges of pI and molecular weights, especially for Trimeresurus sp. The multidimensional chromatographic methods revealed specific differences in venom proteins intra‐species as well as between species and families. We have isolated and identified proteins that may be unique for each species for further studies in the proteome of snake venoms and their potentially use in the pharmaceutical applications.
Use of an electrochemically labeled nucleotide terminator for known point mutation analysis
Authors: Brazill Sara , Hebert Nicole E. , Kuhr Werner G.
Published: August 2003

A novel single nucleotide polymorphism (SNP) assay utilizing an electrochemically tagged chain terminator is described. The system employs the single‐base extension (SBE) technique coupled to capillary gel electrophoresis with end‐column electrochemical detection. A redox‐labeled chain terminator, ferrocene‐acycloATP, is used in the SBE reaction. When the mutation site corresponds to the labeled chain terminator, the extension product is rendered electroactive. The reaction mixture is subsequently separated by capillary gel electrophoresis and the extension product detected at the separation anode with sinusoidal voltammetry. This work demonstrates the first known SNP assay utilizing redox‐active chain terminators coupled to electrochemical detection. The methodology presented could lead to a fast, simple, and cost‐effective SNP scoring system.
Affinity enrichment of plasma membrane for proteomics analysis
Authors: Zhang Wei , Zhou Ge , Zhao Yingxin , White Michael A. , Zhao Yingming
Published: August 2003

Proteomics analysis of plasma membranes from cells exposed to different extracellular environments is potentially a powerful approach for the identification of membrane‐associated proteins responding to these environments. Preparation of high concentration plasma membrane fractions with low contamination from cellular organelles is essential for such studies. Here, we describe an affinity enrichment method, which combines cell surface biotinylation with affinity enrichment by immobilized streptavidin beads, for the isolation of plasma membranes. This method results in a 400‐fold enrichment of plasma membrane relative to endoplasmic reticulum, a major contaminant in standard plasma membrane preparations, and dramatically reduces contamination from other cellular organelles. The biotinylation reaction did not interfere with ligand‐dependent activation of receptor tyrosine kinases or G‐protein coupled receptors, suggesting cell‐surface signal transduction machinery remains functional. Membrane fractions prepared by this method should provide excellent starting materials for membrane proteomics analysis such as studies of dynamic trafficking and regulation of signaling molecules or identification of disease‐specific membrane markers.
N‐Methyl‐D‐glucamine improves the laser‐induced fluorescence capillary electrophoresis performance in the total plasma thiols measurement
Authors: Zinellu Angelo , Carru Ciriaco , Galistu Franca , Usai Maria Franca , Pes Giovanni Mario , Baggio Giovannella , Federici Giorgio , Deiana Luca
Published: August 2003

We describe an ultrarapid capillary electrophoresis with laser‐induced fluorescence (CE‐LIF) method for total plasma thiols measurement. Reduced thiols by 10% tri‐n‐butylphosphine (TBP) were derivatized in 10 min at room temperature with 5‐iodoacetamidofluorescein (5‐IAF) as fluorescent reagent. We show that CE‐LIF allows a baseline separation of total plasma cysteinylglycine, homocysteine, cysteine, and glutathione in less than 5 min when N‐methyl‐D‐glucamine in run buffer was added. CE was compared with high‐performance liquid chromatography (HPLC) with fluorescence detection. The Bland‐Altman test and Passing‐Bablok regression demonstrates that the results obtained by CE‐LIF and by HPLC are highly comparable. The simplified procedure of sample preparation, the short incubation and fast separation times, the high specificity, sensitivity and reproducibility, and the lower cost of analysis suggest that our proposed method can be considered valuable for the automation analysis in a routine laboratory.
Extra‐pair sires as identified by means of standardized across‐gel comparisons of multilocus DNA fingerprints
Authors: Schmoll Tim , Janzon Volker , Epplen Jörg T. , Lubjuhn Thomas
Published: August 2003

Molecular analyses of genetic parentage in wild bird populations demonstrate that extra‐pair paternity (EPP) is common, even in socially monogamous species. After having identified extra‐pair offspring (EPO), an important step is to uncover the identity of extra‐pair sires (EPS). Studies relying on multilocus DNA fingerprinting face the problem that simple between‐gel comparisons of fingerprint banding patterns are imprecise in assigning parentage across gels. To tackle this problem, we developed a method to identify EPS by means of standardized across‐gel comparisons of multilocus DNA fingerprints and applied it in a socially monogamous bird species with high levels of EPP, the coal tit (Parus ater). Scanned DNA fingerprint gels and standard image‐editing software allowed to screen and reliably identify EPS. Overall, EPP was successfully assigned to 32 different EPS for 143 out of 210 (68.1%) EPO detected. This corresponds well to extra‐pair parentage assignment rates revealed by microsatellite‐based studies in congeneric species. Our approach proves especially useful whenever multilocus DNA fingerprints for parentage exclusion exist while microsatellite markers are not available.
A Multistage Well‐Mixed Model for Urea Removal from Industrial Wastewater
Authors: Rahimpour M.R. , Azarpour A.
Published: August 2003

A multistage well‐mixed model for urea removal from industrial wastewater has been proposed. The model incorporates reaction rate of urea hydrolysis and takes into account the effects of backmixing on the reactor performance. The model provides temperature and concentration distribution of different components along the height of reactor. The predicted data of the model were consistent with the plant data indicating the validity of the model. The impact of different parameters on the performance of urea hydrolyzer has been examined. The result of this work showed that an increase in inlet temperature of wastewater and steam flow rate would improve the urea removal efficiency.
Catalyst Development for the Reductive Amination of Isomaltulose
Authors: Cartarius R. , Krause T. , Vogel H.
Published: August 2003

Sucrose is the most from renewable resources produced low molecular mass organic substance, and is widely used as a raw material in industrial processes. The biochemical transformation of sucrose into isomaltulose allows a certain degree of selectivity in particular reactions, starting from sucrose. The reductive amination of isomaltulose (IMU) with n‐dodecylamin (DA) and hydrogen in the presence of a heterogeneous catalyst is one of these reactions, which leads to a product mixture with excellent surfactant properties.
Site‐specific mutagenicity of stereochemically defined 1,N2‐deoxyguanosine adducts of trans‐4‐hydroxynonenal in mammalian cells
Authors: Fernandes Priscilla H. , Wang Hao , Rizzo Carmelo J. , Lloyd R. Stephen
Published: August 2003

Trans‐4‐hydroxynonenal (HNE) is a toxic compound produced endogenously during lipid peroxidation. HNE is a potent electrophile that is reactive with both proteins and nucleic acids. HNE preferentially reacts with deoxyguanosine to form four stereoisomeric HNE‐deoxyguanosine (HNE‐dG) adducts: (6R, 8S, 11R), (6S, 8R, 11S), (6R, 8S, 11S), and (6S, 8R, 11R). These adducts were synthesized into 12‐mer oligodeoxynucleotides, inserted into a DNA shuttle vector and evaluated for the ability of each stereoisomer to induce mutagenesis when replicated through mammalian cells. The resultant mutagenicity of these adducts was related to their stereochemistry, in that two of the HNE‐dG adducts, (6R, 8S, 11R) and (6S, 8R, 11S), were significantly more mutagenic than the (6R, 8S, 11S) and (6S, 8R, 11R) HNE‐dG adducts. These data conclusively demonstrate that HNE‐derived DNA adducts can be mutagenic in mammalian cells and their ability to cause mutations is dictated by their stereochemistry. Environ. Mol. Mutagen. 42:68–74, 2003. © 2003 Wiley‐Liss, Inc.
The comet assay: Genotoxic damage or nuclear fragmentation?
Authors: Rundell Mark S. , Wagner Elizabeth D. , Plewa Michael J.
Published: August 2003

The single cell gel electrophoresis (SCGE) or comet assay is based on the assumption that comet images result from genotoxic damage that ultimately generate DNA single‐ or double‐strand breaks. A criticism of the assay is that some or all of the comet images may be the result of apoptosis‐mediated nuclear fragmentation. The objective of this study was to determine if mutagen‐induced DNA damage leading to strand breakage observed in the SCGE assay was repairable or was due to nonrepairable nuclear fragmentation. Chinese hamster ovary cells were treated with ethylmethanesulfonate, 2‐acetoxyacetylaminofluorene, or H2O2. These mutagens induce genetic damage by different molecular mechanisms. One group of SCGE slides was prepared immediately after treatment, while parallel treated cultures were repeatedly washed and allowed to undergo liquid holding recovery for DNA repair. It was hypothesized that cells with genotoxic damage can repair their genomic DNA, while apoptotic cells cannot reverse nuclear fragmentation. We found a significant decrease in the tail moments of nuclei from mutagen‐treated cells after 4 hr of liquid holding. However, this measurement may represent only those cells capable of repair. Apoptotic cells may continue DNA fragmentation during the recovery time and this DNA may become so diffuse that the nuclei disappear after electrophoresis. To overcome this possible artifact, images of nuclei were captured before and after alkaline electrophoresis. Constellations of nuclei were located on SCGE slides by their coordinates on the microscope stage. We found that no nuclei were lost due to apoptotic nuclear fragmentation and DNA migration. Even the so‐called “hedgehog” comet images with extreme DNA damage were not lost during liquid holding. These data support the conclusion that mutagen‐induced DNA damage is the principal cause of the damage measured in the comet assay. Environ. Mol. Mutagen. 42:61–67, 2003. © 2003 Wiley‐Liss, Inc.
Urinary excretion of 8‐hydroxy‐2‐deoxyguanosine and 1‐hydroxypyrene in coke‐oven workers
Authors: Wu Ming‐Tsang , Pan Chih‐Hong , Huang Yeou‐Lih , Tsai Perng‐Jy , Chen Chiou‐Jong , Wu Trong‐Neng
Published: August 2003

Coke‐oven workers (COWs) are occupationally exposed to high concentrations of polycyclic aromatic hydrocarbons (PAH). Urinary 8‐hydroxy‐2‐deoxyguanosine (8‐OH‐dG) and 1‐hydroxypyrene (1‐OHP) are biological markers of oxidative DNA damage and PAH metabolism, respectively. We investigated the relationship between urinary 8‐OH‐dG and 1‐OHP in 217 Taiwanese COWs, 55 topside‐oven, and 162 sideoven workers. For topside‐oven workers, mean 8‐OH‐dG and 1‐OHP concentrations (ng/ml ± SD) were 13.8 ± 12.0 and 93.5 ± 104.4, respectively. These levels were significantly higher than those for sideoven workers: 10.2 ± 7.9 ng/ml (P = 0.04) and 19.8 ± 28.6 ng/ml (P < 0.001), respectively. Individual urinary 8‐OH‐dG concentrations were directly correlated with urinary 1‐OHP concentrations: the higher the 1‐OHP level, the higher the 8‐OH‐dG level (Spearman correlation coefficients: r = 0.43, P < 0.0001, n = 217). Multiple regression analysis indicated that a 10‐fold increase in 1‐OHP was associated with a 1.91‐fold increase in 8‐OH‐dG. Compared to no vitamin intake, intake of at least one multiple vitamin pill per week reduced 8‐OH‐dG excretion (P = 0.02). Our findings suggest that urinary 1‐OHP and 8‐OH‐dG reflect occupational PAH exposure and oxidative DNA damage in COWs. In addition, multiple vitamins may reduce oxidative stress caused by PAH exposure. Environ. Mol. Mutagen. 42:98–105, 2003. © 2003 Wiley‐Liss, Inc.
cDNA microarray gene expression profiling of hydroxyurea, paclitaxel, and p‐anisidine, genotoxic compounds with differing tumorigenicity results
Authors: Lee Michael , Kwon Jung , Kim Se Nyun , Kim Ja Eun , Koh Woo Suk , Kim Eun‐Joo , Chung Moon‐Koo , Han Sang‐Seop , Song Chang Woo
Published: August 2003

The potential application of toxicogenomics to predictive toxicology has been discussed widely, but the utility of the approach remains largely unproven. Using cDNA microarrays, we compared the gene expression profiles produced in mouse lymphoma cells by three genotoxic compounds, hydroxyurea (a carcinogen), p‐anisidine (a noncarcinogen), and paclitaxel (carcinogenicity unknown). To minimize the effect of biological variability and technological limitations, quadruplicate observations were made for each compound and a subset of genes yielding reproducible induction/repression was selected for comparison. A method was applied to attach normalized expression data to genes with a low false‐discovery rate (<0.1) to yield more confidence regarding differential expression. This analysis identified genotoxicity‐specific gene expression. Seven genes were consistently upregulated and 12 downregulated more than 2‐fold by the three genotoxic compounds. Using additional genes, the expression pattern induced by the genotoxic noncarcinogen, p‐anisidine, was readily distinguished from that associated with the genotoxic carcinogen, hydroxyurea. Comparison of paclitaxel‐induced expression data to data for p‐anisidine and hydroxyurea suggested that paclitaxel's profile is more similar to the genotoxic noncarcinogen. With further supporting evidence it may be possible to perform large‐scale monitoring of gene expression during drug and chemical development that can provide an early warning of potential toxicological responses. Environ. Mol. Mutagen. 42:91–97, 2003. © 2003 Wiley‐Liss, Inc.
In vitro assessment of mutagenicity and clastogenicity of BDE‐99, a pentabrominated diphenyl ether flame retardant
Authors: Evandri Maria G. , Mastrangelo Sabina , Costa Lucio G. , Bolle Paola
Published: August 2003

Polybrominated diphenyl ethers (PBDEs), which are widely used as flame retardants, are considered persistent organic pollutants. To date, the available toxicological data on PBDEs are limited and were primarily obtained by studying technical blends. The present study was undertaken to investigate the genotoxicity of the pure congener 2,2′,4,4′,5‐brominated diphenyl ether (BDE‐99), one of the major isomers present in penta‐commercial products. Bacterial reverse mutation assays in Salmonella typhimurium strains TA98 and TA100 and in Escherichia coli WP2 uvrA, and the Allium cepa chromosome aberration test were carried out to evaluate mutagenicity and clastogenicity. The experimental design also involved testing a well‐known polychlorinated biphenyl (PCB) mixture, Aroclor® 1254, which is structurally related to PBDEs. BDE‐99 was negative in the bacterial mutagenicity assays, with and without S9 mix. Also, the frequency of structural chromosome aberrations was not significantly higher than the control and no signs of cytotoxicity were observed in BDE‐99‐treated A. cepa. Aroclor® 1254 was not mutagenic, but it induced a significant increase in chromosomal aberrations in A. cepa. In conclusion, BDE‐99 was not mutagenic in S. typhimurium or E. coli, or clastogenic in A. cepa; however, the possibility that PBDEs might act through an epigenetic mechanism cannot be excluded. Environ. Mol. Mutagen. 42:85–90, 2003. © 2003 Wiley‐Liss, Inc.
Mutation frequency analysis of mononucleotide and dinucleotide repeats after oxidative stress
Authors: Yamada Nazumi A. , Parker Jennifer M. , Farber Rosann A.
Published: August 2003

Many tumors exhibit genetic instability at the DNA sequence level in the form of frameshift mutations in simple repeats (microsatellite instability). A high level of microsatellite instability, such as that seen in hereditary nonpolyposis colorectal cancer (HNPCC), arises from defects in the mismatch repair pathway. A low level of microsatellite instability is found in some non‐HNPCC‐associated cancers, such as those of the breast and lung, and is not attributable to mismatch repair defects. We hypothesized that oxidative DNA damage may be at least partly responsible for the generation of microsatellite mutations in these tumors. We investigated whether oxidative DNA damage can induce microsatellite mutations in mismatch repair‐proficient cultured cells. Telomerase‐immortalized normal human fibroblasts were stably transfected with a plasmid containing a tk‐neo fusion gene, such that the neo coding region was placed out of frame by the presence of an upstream microsatellite sequence. Cells were treated with H2O2 and mutation frequencies were determined for G17, A17, and (CA)17 repeats. Mutation frequencies of mononucleotide repeats in cells with the neo gene in the (+1) reading frame were reduced after treatment. No effect was observed in cells with the mononucleotide repeats in the (–1) reading frame. A small increase in mutation frequency was observed in cells with the (CA)17 repeat. Our data suggest that diploid human cells may have protective mechanisms that prevent the induction of microsatellite mutations by a short exposure to high levels of oxidative stress. Environ. Mol. Mutagen. 42:75–84, 2003. © 2003 Wiley‐Liss, Inc.
A model of sensitivity: 1,3‐butadiene increases mutant frequencies and genomic damage in mice lacking a functional microsomal epoxide hydrolase gene
Authors: Wickliffe Jeffrey K. , Ammenheuser Marinel M. , Salazar James J. , Abdel‐Rahman Sherif Z. , Hastings‐Smith Darlene A. , Postlethwait Edward M. , Lloyd R. Stephen , Ward Jonathan B.
Published: August 2003

The specific role that polymorphisms in xenobiotic metabolizing enzymes play in modulating sensitivity to 1,3‐butadiene (BD) genotoxicity has been relatively unexplored. The enzyme microsomal epoxide hydrolase (mEH) is important in detoxifying the mutagenic epoxides of BD (butadiene monoepoxide [BDO], butadiene diepoxide [BDO2]). Polymorphisms in the human mEH gene appear to affect the function of the enzyme. We exposed mice with normal mEH activity (WT) and knockout mice without mEH activity (KO) to 20 ppm BD (inhalation) or 30 mg/kg BDO2 (intraperitoneal [IP] injection). We then compared Hprt mutant frequencies (MFs) among these groups. KO mice exposed to BD exhibited a significant (P < 0.05) 12.4‐fold increase in MF over controls and a significant 5.4‐fold increase in MF over exposed WT mice. Additionally, KO mice exposed to BDO2 exhibited a significant 4.5‐fold increase in MF over controls and a significant 1.7‐fold increase in MF over exposed WT mice. We also compared genomic damage in WT and KO mice (comet tail moment) following IP exposure to 3 mg/kg and 30 mg/kg BDO2. KO mice exposed to 3 mg/kg exhibited significantly more DNA damage than controls (7.5–12.1‐fold increase) and exposed WT mice (3 mg/kg; 4.8‐fold increase). KO mice exposed to 30 mg/kg BDO2 exhibited significantly more DNA damage than all other groups (2.3–27.9‐fold increase). Correlation analysis indicated that a significant, positive relationship (r2 = 0.92) exists between comet‐measured damage and Hprt MFs. The lack of mEH activity increases the genetic sensitivity of mice exposed to BD and BDO2. This model should facilitate a mechanistic understanding of the observed variation in human genetic sensitivity following exposure to BD. Environ. Mol. Mutagen. 42:106–110, 2003. © 2003 Wiley‐Liss, Inc.
Frameshift mutations induced by three classes of acridines in the lacZ reversion assay in Escherichia coli: Potency of responses and relationship to slipped mispairing models
Authors: Hoffmann George R. , Calciano Margaret A. , Lawless Bryan M. , Mahoney Kathleen M.
Published: August 2003

The frameshift mutagenicity of 9‐aminoacridine (9AA) was compared with that of quinacrine, the acridine mustards ICR‐191 and quinacrine mustard (QM), and the nitroacridine Entozon in the lacZ reversion assay in Escherichia coli. As intercalating agents, 9AA and quinacrine cause mutations through noncovalent associations with DNA. Mustards and nitroacridines form covalent adducts in DNA and give rise to different spectra of mutations. Quinacrine and 9AA most effectively induced −1 frameshifts in a run of guanine residues, with 9AA being the more potent mutagen. They also induced +G frameshifts. The acridine mustard ICR‐191 was a stronger mutagen than 9AA, owing largely to its potent induction of +G frameshifts. QM induced +G frameshifts more strongly than did its nonreactive counterpart quinacrine. The nitroacridine Entozon differed from the other acridines in being a potent inducer of −2 frameshifts, but it was less effective in inducing ±1 frameshifts. Quinacrine, although a simple intercalator, induced all five kinds of frameshift mutations detected in the assay, as did the acridine mustards. Although +A and −A frameshifts were induced, adenine runs were less susceptible to acridine mutagenesis than guanine runs. The patterns of frameshift mutagenicity in the lacZ assay are similar to those in an assay based on the reversion of mutations in the tetracycline‐resistance gene of the plasmid pBR322. The similarity suggests that the responses reflect the inherent bacterial mutagenicity of the compounds in the local sequence context and are not highly dependent on the broader sequence context. The results are interpreted with respect to slipped mispairing models of frameshift mutagenesis. Environ. Mol. Mutagen. 42:111–121, 2003. © 2003 Wiley‐Liss, Inc.
A twenty‐one‐year record of surface change on a Namib linear dune
Authors: Livingstone Ian
Published: August 2003

Repeated surveying of two sites on a Namib linear dune between 1980 and 2001 provides a 21‐year record of dune surface change. The surveys conﬁrm the view that the dunes are not inactive relics but are responding to the present‐day wind regime. They also provide no evidence that the dunes are migrating laterally. Examination of wind data for the survey period provides some evidence that the form of the crest of the dunes is actively responding to the natural year‐by‐year climate variability, such that an increase in the frequency of easterly winds leads to the development of a double‐crested form while fewer easterly winds lead to a single‐crested form. Copyright © 2003 John Wiley & Sons, Ltd.
A simple low‐cost sand catcher for wind‐tunnel simulations
Authors: Cornelis Wim M. , Gabriels Donald
Published: August 2003

A simple low‐cost sand catcher has been developed for use in wind‐tunnel experiments. It is 500 mm high with a 300 mm by 20 mm inlet opening, and is designed to measure total mass transport directly. The length is 280 mm and its walls slowly expand at an angle of 5·6°. The top view is similar to that of the widely used BSNE sampler. Each sidewall is vented with three ventilation screens. Two sets of experiments were conducted on dune sand and at different wind velocities to investigate to what degree the catcher samples isokinetically, efﬁciently and non‐selectively. The results indicate that the catcher measures sufﬁciently isokinetically (inlet wind velocity over outside wind velocity >0·9). Catch efﬁciency was around 0·75 and the degree of non‐selectivity was >0·80 for 95 per cent of the particle sizes of the test material. It was also observed that the inﬂuence of wind velocity on the tested sampler characteristics was of minor importance so that no speciﬁc corrections need to be made for different wind velocities. Copyright © 2003 John Wiley & Sons, Ltd.
Particle path length distributions in meandering gravel‐bed streams: results from physical models
Authors: Pyrce Richard S. , Ashmore Peter E.
Published: August 2003

In gravel‐bed rivers with well‐deﬁned pool–bar morphology, the path length of transported bed particles must be, at least during ‘channel‐forming’ ﬂows, equal to the length scale of the morphology. This is the basis for some methods for estimating bed material transport rates. However, previous data, especially from ﬁeld tests, are often strongly positively skewed with mean much shorter than the pool–bar spacing. One possible explanation is that positively skewed distributions occur only in channels lacking distinct pool–bar topography or only at lower discharges in pool–bar channels. A series of ﬂume experiments using ﬂuorescent tracers was used to measure path length distributions in low‐sinuosity meandering channels to assess the relation with channel morphology and ﬂow conditions. At channel‐forming ﬂows, 55 to 75 per cent of the tracer grains were deposited on the ﬁrst point bar downstream of the point of tracer input, with 15 per cent passing beyond the ﬁrst bar. Path length distributions are symmetrical with mean equal to the pool–bar spacing and can be described with a Cauchy distribution. In some cases there was a secondary mode close to the point of tracer introduction; this bimodal distribution ﬁts a combined gamma–Cauchy distribution. Only when discharge was reduced below the channel‐forming ﬂow were frequency distributions unimodal and positively skewed with no relation to the pool–bar spacing. Thus, path length distributions become more symmetrical, and mean path length increases to coincide with pool–bar spacing, as ﬂow approaches channel‐forming conditions. This is a substantial modiﬁcation of existing models of particle transfer in gravel‐bed rivers. Copyright © 2003 John Wiley & Sons, Ltd.
Short‐term erosion rates from a 7Be inventory balance
Authors: Wilson Christopher G. , Matisoff Gerald , Whiting Peter J.
Published: August 2003

Detailed soil erosion studies beneﬁt from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for 7Be was used to calculate sediment erosion in a 30·73 m2 plot during a series of runoff‐producing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, Iowa, USA. The inventory balance included determination of the pre‐ and post‐storm 7Be inventories in the soil, the atmospheric inﬂux of 7Be during the event, and proﬁles of the 7Be activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the 7Be inventory balance was 0·058 g cm−2, which is 23 per cent of the annual average erosion determined using 137Cs inventories. The calculated erosion from the mass balance is similar to the 0·059 g cm−2 of erosion estimated from the amount of sediment collected at the outlet of the 6 ha ﬁeld during the study period and the delivery ratio (0·64). The inventory balance of 7Be provides a new means for evaluating soil erosion over the time period most relevant to quantifying the prediction of erosion from runoff. Copyright © 2003 John Wiley & Sons, Ltd.
The precision of sampling grain‐size percentiles using the Wolman method
Authors: Green Julian C.
Published: August 2003

The precision of sampling different grain‐size percentiles in comparison to each other is of signiﬁcance for choosing which percentile is appropriate to characterize riverbed surface sediments. The traditional view, based on normal grain‐size distributions derived by the Wolman grid‐by‐number method, has identiﬁed the median percentile as having the highest sampling precision. However, grain‐size distributions are highly variable and often fail to follow a theoretical distribution. This paper presents both theoretical and empirical techniques to determine the precision of sampling different percentiles. These methods are then applied to a range of natural distributions found in UK rivers. It is found that grains between the 66th and 91st percentiles are the most precisely sampled, with maximum precision obtained with the 73rd percentile. Copyright © 2003 John Wiley & Sons, Ltd.