bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of a sodium channel mutation in pyrethroid resistance in Cydia pomonella L, and development of a diagnostic test
Authors: Brun‐Barale Alexandra , Bouvier Jean‐Charles , Pauron David , Bergé Jean‐Baptiste , Sauphanor Benoit 
Published: January 2005

AbstractPopulations of the codling moth, Cydia pomonella L (Lepidoptera, Tortricidae) have developed resistance to several classes of insecticide such as benzoylureas, juvenile hormone analogues, ecdysone agonists and pyrethroids, but the corresponding resistance mechanisms have not been extensively studied. Knockdown resistance (kdr) to pyrethroid insecticides has been associated with point mutations in the para sodium channel gene in a great variety of insect pest species. We have studied two susceptible strains (S and Sv) and two resistant strains (Rt and Rv) of C pomonella that exhibited 4‐ and 80‐fold resistance ratios to deltamethrin, respectively. The region of the voltage‐dependent sodium channel gene which includes the position where kdr and super‐kdr mutations have been found in Musca domestica L was amplified. The kdr mutation, a leucine‐to‐phenylalanine replacement at position 1014, was found only in the Rv strain. In contrast, the super‐kdr mutation, a methionine‐to‐threonine replacement at position 918, was not detected in any C pomonella strain. These data allowed us to develop a PCR‐based diagnostic test (PASA) to monitor the frequency of the kdr mutation in natural populations of C pomonella in order to define appropriate insecticide treatments in orchards. Copyright © 2005 Society of Chemical Industry
Jahn–Teller effect and electron correlation in alkali doped fullerides
Authors: Chibotaru L. F. 
Published: January 2005

AbstractThe interplay between Jahn–Teller effect and electron correlation in alkali doped fullerides is reviewed for compounds from both sides of Mott–Hubbard transition. In Mott–Hubbard fullerides the nature of low‐lying excitations strongly depends on the symmetry of the compounds, corresponding either to spin (Heisenberg) type for low symmetry compounds (K3(NH3)C60) or to spin‐vibronic superexchange for cubic compounds (Li3(NH3)6C60). In the band fullerides (A3C60, A4C60, A = K, Rb) the Jahn–Teller effect leads to a splitting of the cubic band structure in three or two unequally populated subbands (orbital disproportionation), which gives rise to a number of features in the spectroscopy of these compounds. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐polarized transport through carbon nanotubes
Authors: Krompiewski S. 
Published: January 2005

AbstractCarbon nanotubes (CNT) belong to the most promising new materials which can in the near future revolutionize the conventional electronics. When sandwiched between ferromagnetic electrodes, the CNT behaves like a spacer in conventional spin‐valves, leading quite often to a considerable giant magneto‐resistance effect (GMR). This paper is devoted to reviewing some topics related to electron correlations in CNT. The main attention however is directed to the following effects essential for electron transport through nanotubes: (i) nanotube/electrode coupling and (ii) inter‐tube interactions. It is shown that these effects may account for some recent experimental reports on GMR, including those on negative (inverse) GMR. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The physics of quantum impurities – a bridge from micro/nano to macro systems
Authors: Pruschke Th. 
Published: January 2005

AbstractWe will give a comprehensive introduction into the concept of quantum impurities and survey on where and why quantum impurity problems arise in modern solid‐state physics. The physical properties of these systems and their applications will be discussed for a selected set of examples. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Onset of metallic ferromagnetism in a doped spin–orbital chain
Authors: Daghofer Maria , Oleś Andrzej M. , von der Linden Wolfgang 
Published: January 2005

AbstractStarting from a spin–orbital model for doped manganites, we investigate a competition between ferromagnetic and antiferromagnetic order in a one‐dimensional model at finite temperature. The magnetic and orbital order at half filling support each other and depend on a small antiferromagnetic superexchange between t2g spins and on an alternating Jahn–Teller potential. The crossover to a metallic ferromagnetic phase found at finite doping is partly suppressed by the Jahn–Teller potential which may localize eg electrons. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large‐scale quantum effects in biological systems
Authors: Mesquita Marcus V. , Vasconcellos Áurea R. , Luzzi Roberto , Mascarenhas Sergio 
Published: January 2005

AbstractParticular aspects of large‐scale quantum effects in biological systems, such as biopolymers and also microtubules in the cytoskeleton of neurons which can have relevance in brain functioning, are discussed. The microscopic (quantum mechanical) and macroscopic (quantum statistical mechanical) aspects, and the emergence of complex behavior, are described. This phenomena consists of the large‐scale coherent process of Fröhlich–Bose–Einstein condensation in open and sufficiently far‐from‐equilibrium biopolymers. Associated with this phenomenon is the presence of Schrödinger–Davydov solitons, which propagate, undistorted and undamped, when embedded in the Fröhlich–Bose–Einstein condensate, thus allowing for the transmission of signals at long distances, involving a question relevant to bioenergetics. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A theoretical study of vibrational properties of neutral and cationic B12 clusters
Authors: Lau Kah Chun , Deshpande Mrinalini , Pandey Ravindra 
Published: January 2005

AbstractCalculations based on density functional theory predict the ground state of B12 and B to be a convex planar configuration with C1 symmetry. A small ionization‐induced structural change in B12 is also predicted. It is suggested that multicentered bonds together with delocalized charge density are dominant factors in stabilizing the planar configuration over 3D configuration for B12 and B. The calculated vibrational frequencies lie in the range of 200–1328 cm−1 in which the high‐frequency modes are associated with asymmetric stretching of the boron atoms located at the cluster surface. The infrared spectra of both neutral and cationic B12 show similar infrared active modes in the high‐frequency region, but different modes in the low‐frequency region due to dissimilar atomic charges in the cationic B12. The combined effect of charge delocalization and reduced dimensionality is reflected in the calculated static dipole polarizability of these clusters. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Electrospray ionization tandem mass spectrometry of model peptides reveals diagnostic fragment ions for protein ubiquitination
Authors: Esteban Warren Maria R. , Parker Carol E. , Mocanu Viorel , Klapper David , Borchers Christoph H. 
Published: January 2005

AbstractIn this work, synthetic peptides were used to determine the fragmentation behavior of ubiquitinated peptides and to find ions diagnostic for peptide ubiquitination. The ubiquitin‐calmodulin peptide1 was chosen as the model peptide for naturally occurring ubiquitinated proteins cleaved with endoproteinase gluC. In addition, the fragmentation behavior of model ubiquitinated peptides produced by tryptic digestion was also of great interest since the standard protocols for proteomics‐based protein identification use trypsin as the protease. Attachment of ubiquitin to a target protein results in a branched structure, but only ions from the ubiquitin side chain (and the lysine to which it is attached) can be used as diagnostic ions, since fragment ions that contain other amino acids from the parent protein will vary in mass. Characteristic b‐type fragment ions from the gluC cleavage of the ubiquitin side chain (designated as b ions) were found which involve only the ubiquitin tail (b2, b3, b4, b5 and b6 ions at m/z 189.06, 302.12, 439.18, 552.30 and 651.30, respectively). Maximum production of these ions occurred at a collision energy of 45 eV in a Q‐TOF instrument. Although a non‐ubiquitinated peptide may produce isobaric fragment ions, it is unlikely that it can produce these ions in combination. With liquid chromatography/tandem mass spectrometry (LC/MS/MS) experiments, ubiquitinated peptides can readily be determined by surveying the reconstructed or extracted ion chromatograms of the diagnostic fragment ions for common peaks. Characteristic ions resulting from tryptic cleavage of the side chain were found in cleavage products with a missed cleavage, resulting in a LRGG‐ tag instead of a GG‐ tag. For the LRGG‐tagged peptide, diagnostic MS/MS fragment ions (at m/z 270.17 and 384.21) from the ubiquitin tail (b2 and b4, respectively) were found, along with an internal fragment ion (LRGGK‐28) at m/z 484.30. These ions should prove useful in precursor‐ion scanning experiments for identifying peptides modified by attachment of ubiquitin, and for locating the site of ubiquitin attachment. Copyright © 2005 John Wiley & Sons, Ltd.
Differential adduction of proteins vs. deoxynucleosides by methyl methanesulfonate and 1‐methyl‐1‐nitrosourea in vitro
Authors: Zhang Fagen , Bartels Michael J. , Pottenger Lynn H. , Gollapudi B. Bhaskar 
Published: January 2005

AbstractThe reactions of two model mutagenic and carcinogenic alkylating agents, N‐methyl‐N‐nitrosourea (MNU) and methyl methanesulfonate (MMS), with proteins and deoxynucleosides in vitro, were investigated. The protein work used an approach involving trypsin digestion and high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI‐MS/MS). This technique permitted identification of the specific location of protein adduction by both MNU and MMS with commercial apomyoglobin and human hemoglobin, under physiological conditions. MNU treatment resulted in predominantly carbamoylation adducts on the proteins, but in contrast only methylated protein adducts were found following treatment with MMS. Further analyses, using TurboSequest®, and the Scoring Algorithm for Spectral Analysis (SALSA), revealed that MNU carbamoylation was specific for modification of either the N‐terminal valine or the free amino group in lysine residues of apomyglobin and human hemoglobin. However, MMS methylation modified the N‐terminal valine and histidine residues of the proteins. Despite their clear differences in protein modifications, MNU and MMS formed qualitatively the same methylated deoxynucleoside adduct profiles with all four deoxynucleosides in vitro under physiological conditions. In light of their different biological potencies, where MMS is considered a ‘super clastogen’ while MNU is a ‘super mutagen’, these differences in reaction products with proteins vs. deoxynucleosides may indicate that these two model alkylating agents work via different mechanisms to produce their mutagenic and carcinogenic effects. Copyright © 2005 John Wiley & Sons, Ltd.
Benzene‐assisted atmospheric‐pressure chemical ionization: a new liquid chromatography/mass spectrometry approach to the analysis of selected hydrophobic compounds
Authors: Perazzolli Chiara , Mancini Ines , Guella Graziano 
Published: January 2005

AbstractCharge‐exchange reactions involving benzene have been successfully exploited to increase the sensitivity of atmospheric‐pressure chemical ionization mass spectrometry (APCI‐MS) towards hydrophobic compounds of significant environmental relevance which are not detectable with the ordinary APCI techniques. Among them, good sensitivity have been found for (a) highly chlorinated biphenyl derivatives such as dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethene (DDE); (b) cyclopentadienes such as Aldrin and its epoxy derivatives Dieldrin and Endrin; and (c) dibenzofurans and dibenzo‐para‐dioxins such as 2,3,7,8‐tetrachlorodibenzofuran (2,3,7,8‐TCDF) and 2,3,7,8‐tetrachloro‐dibenzo‐para‐dioxin (2,3,7,8‐TCDD). The reactant benzene molecules were introduced into the source either through the nebulizer gas or by direct post‐column addition of neat liquid, whereas the targeted compounds were analyzed using a high‐performance liquid chromatography (HPLC) RP‐18 column using methanol/water solutions as mobile phase. By using benzene as post‐column reagent, positive ion mode detection was proven to be significantly enhanced as compared with APCI measurements carried out without benzene assistance. Copyright © 2005 John Wiley & Sons, Ltd.
Implications of enzymatic, acidic and thermal hydrolysis of DNA on the occurrence of cross‐linked melphalan DNA adducts
Authors: Van den Driessche Bart , Lemière Filip , Witters Erwin , Van Dongen Walter , Esmans Eddy L. 
Published: January 2005

AbstractCalf thymus DNA was treated with melphalan, a nitrogen mustard, and the formation of melphalan cross‐linked DNA adducts was investigated. These cross‐linked adducts could not be detected either in the enzymatically or in the thermally generated DNA hydrolysates. However, a search for DNA cross‐linked adducts in the hydrolysates obtained under acidic conditions revealed the presence of different types of cross‐links, mainly containing an adenine moiety. These results are very important because they show that the detection of cross‐links is dependent on the hydrolytic procedure used and that these cross‐linked adducts are formed under totally different reaction conditions from those in in vivo situations. This can explain the very low abundance or even the absence of cross‐linked adducts in nitrogen mustard treated animals. The generally accepted theory that the anti‐cancer activity of bifunctional mustards such as melphalan is due to cross‐linking of DNA strands remains therefore from our point of view questionable. Copyright © 2005 John Wiley & Sons, Ltd.
Tandem mass spectra of transition‐metal ion adducts of glycosyl dithioacetals; distinction among stereoisomers
Authors: Madhusudanan K. P. , Kumar Brijesh , Tiwari Pallavi , Madhusudan Soni Kamlesh , Misra A. K. 
Published: January 2005

AbstractElectrospray ionization mass spectra of some glycosyl dithioacetals recorded in the presence of transition‐metal chlorides, XCl2 (where X = Co, Mn and Zn), give abundant adduct ions such as [M+XCl]+ and [2MH+X]+ and minor ions such as [MH+X]+ and [2M+XCl]+. The tandem mass spectra of these adducts show characteristic elimination of neutral molecules such as H2O, HCl, EtSH, CH2O, C2H4O2/C2H4O. [M+XCl]+ ions fragment readily and the fragmentation appears to be stereochemically controlled as the relative abundances of the fragments are different for three stereoisomers. The added metal is lost as neutral molecules in the form of XCl(OH) and XCl(SEt). This is a predominant pathway in the ZnCl+ adducts. [2M+XCl]+ ions fragment preferentially by elimination of HCl, indicating strong metal interactions in the resulting dimeric [2MH+X]+ ion. As there are several electron‐rich centers in the molecule, the dimeric complex [2MH+X]+ can have several structures and the observed fragmentations may reflect the sum of those of all these structures. The dimeric complexes fragment by elimination of neutral molecules leaving the dimeric interactions intact. The extent of fragmentation varies for the stereoisomers, leading to stereochemical differentiation. Copyright © 2005 John Wiley & Sons, Ltd.
Isotope analysis of hydrocarbons: trapping, recovering and archiving hydrocarbons and halocarbons separated from ambient air
Authors: Pupek M. , Assonov S. S. , Mühle J. , Rhee T. S. , Oram D. , Koeppel C. , Slemr F. , Brenninkmeijer C. A. M. 
Published: January 2005

AbstractIt is argued that isotope analysis of atmospheric non‐methane hydrocarbons (NMHCs) and, in particular, the analysis of the deuterium/hydrogen (D/H) ratio is valuable because the dominant self‐cleansing property of the troposphere is based on the OH radical which removes, e.g., CH4 and other alkanes by H‐atom abstraction, which induces large kinetic isotope effects. The major obstacle in applying D/H isotope analysis to atmospheric NMHCs is not only the low abundance of D itself but, in particular, the low concentrations of NMHCs in the parts per trillion range. We show how a selection of NMHCs can be quantitatively separated from 300 L air samples together with CO2 as carrier gas matrix, by using high efficiency cryogenic traps. After diluting the extracted NMHC mixtures with hydrocarbon free air, and determining the mixing ratios, good agreement with original whole air sample analysis exists for alkanes and several halocarbons. For unsaturated hydrocarbons and some other halocarbons the extraction and recovery yield under the given conditions fell considerably, as a function of boiling point. Furthermore, the mixture of NMHCs in the CO2 matrix is proven to remain unchanged over several years when conveniently stored in glass ampoules. The ‘extracts’ or ‘concentrates’ of condensables extracted from larger air samples will enable the D/H isotope analysis of ultra trace gases in the atmosphere. Copyright © 2005 John Wiley & Sons, Ltd.
Multidimensional statistical analysis applied to electron ionization mass spectra to determine steroid stereochemistry
Authors: Le Bizec Bruno , Antignac Jean‐Philippe , Bertrand Dominique , Qannari El Mostafa , Andre François 
Published: January 2005

AbstractThe differentiation of stereoisomers on the basis of their mass spectra only is usually a difficult challenge even when an informative ionization technique such as electron ionization is used; this is particularly the case for steroids. In this study, multivariate statistical techniques have been applied to the mass spectra of derivatized 5ξ‐androstane‐3ξ,17ξ‐diols (ξ = α,β) in order to investigate the possibility of discrimination among the different isomers. After collection of the data from the mass spectra (20 replicates for each of the 8 isomers), each ion was considered as a statistical variable and each mass spectrum as an observation. The more discriminative variables (42 out of the 160 initial ones) were selected using the analysis of variance technique (ANOVA). Thereafter, a linear discriminant analysis (LDA) allowed us to set up a predictive model for stereochemistry determination. The two‐dimensional graphical display of the 160 observations on the basis of the canonical variables derived from LDA made it possible to separate the eight isomers. The discrimination of 5α and 5β isomers as well as 3α and 3β was unambiguous, whereas, the discrimination of 17α and 17β epimers was less obvious. The robustness of the model was checked with 40 mass spectra recorded over a 6‐month period on different quadrupole mass spectrometers and under different signal acquisition conditions. The percentage of correct assignment of these ‘unknown’ stereoisomers was 92%; only three 17α and 17β epimers were not correctly plotted in the expected zone. Nevertheless, the performance score was better than those observed with traditional mass spectral libraries. Furthermore, this statistical approach allowed us to identify the main fragment ions involved in the discrimination between isomers: m/z 256 and 421 for isomers 5a‐5b; m/z 241 and 331 for isomers 5α3α‐5α3β; m/z 143 and 162 for isomers 5β3α‐5β3β; and m/z 255 for epimers 17α‐17β. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of the ionophoric coccidiostats narasin, monensin, lasalocid and salinomycin in eggs by liquid chromatography/tandem mass spectrometry
Authors: Mortier Leen , Daeseleire Els , Peteghem Carlos Van 
Published: January 2005

AbstractA sensitive and selective liquid chromatographic tandem mass spectrometric method (LC/MS/MS) for the simultaneous detection of the ionophoric coccidiostats narasin, monensin, lasalocid and salinomycin in whole eggs has been developed. A very simple sample preparation consisting of an extraction with an organic solvent was carried out. Sample extracts were injected into the LC/MS/MS system on a C18 column and an isocratic elution was performed. Nigericin was used as internal standard. The precursor ions produced by electrospray positive ionisation were selected for collisional dissociation with argon into product ions. Validation of the methods was performed based on Commission Decision 2002/657/EC.1 CCα was found to be 1 μg/kg for all four compounds. Monitoring of Belgian egg samples in 2004 revealed that residues of salinomycin, lasalocid and monensin could be found. Copyright © 2005 John Wiley & Sons, Ltd.
Early prediction of wheat quality: analysis during grain development using mass spectrometry and multivariate data analysis
Authors: Ghirardo Andrea , Sørensen Helle Aagaard , Petersen Marianne , Jacobsen Susanne , Søndergaard Ib 
Published: January 2005

AbstractMatrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry and multivariate data analysis have been used for the determination of wheat quality at different stages of grain development. Wheat varieties with one of two different end‐use qualities (i.e. suitable or not suitable for bread‐making purposes) were investigated. The samples were collected from grains from 15 until 45 days post‐anthesis (dpa). Gluten proteins from wheat grains were extracted and subsequently analysed by mass spectrometry. Discrimination partial least‐squares regression and soft independent modelling of class analogy were used to determine the quality of new and unknown wheat samples. With these methods, we were able to predict correctly the end‐use qualities at every stage investigated. This new fast technique, based on the rapidity of mass spectrometry combined with the objectivity of multivariate data analysis, offers a method that can replace the traditional rather time‐consuming ones such as gel electrophoresis. This study focused on the determination of wheat quality at 15 dpa, when the grain is due for harvest 1 month later. Copyright © 2005 John Wiley & Sons, Ltd.
The dual PPARα/γ agonist, ragaglitazar, improves insulin sensitivity and metabolic profile equally with pioglitazone in diabetic and dietary obese ZDF rats
Authors: Pickavance Lucy C , Brand Christian L , Wassermann Karsten , Wilding John P H 
Published: January 2005

In 6‐ and 10‐week‐old obesity‐prone (fa/fa) Zucker diabetic fatty (ZDF) rats, effects of prevention and intervention therapies, respectively, were compared between PPARα/γ agonist, ragaglitazar (RAGA) and separate PPARγ and α agonists, pioglitazone (PIO) and bezafibrate (BF).
In a separate study, lean (+/+) ZDF rats fed highly palatable chow to induce dietary obesity and insulin resistance were treated similarly. To test insulin‐secretory capacity, all animals underwent a hyperglycaemic clamp.
Insulin sensitivity was improved equally by RAGA and PIO in fa/fa rats subjected to both prevention and intervention treatments (e.g., prevention HOMA‐IR: −71 and −72%, respectively), as was hyperglycaemia (both −68%). BF had no effect on either parameter in any study. Plasma lipids were markedly reduced (by 48–77%) by RAGA in all studies, equivalent to PIO, but to a greater extent than BF.
RAGA improved β‐cell function (HOMA‐β) more than three‐fold with prevention and intervention therapies, whereas PIO showed improvement only in intervention therapy. Consistent with improved insulin sensitivity, glucose infusion rate during the clamp was 60% higher in RAGA‐treated animals subjected to prevention therapy, but there was little additional insulin‐secretory response, suggesting that insulin secretion was already maximal.
Thus, RAGA and PIO equally improve metabolic profile in ZDF rats, particularly when administered early in the course of diabetes. They also improve β‐cell function, although this is better demonstrated through indices incorporating fasting insulin and glucose concentrations than through the hyperglycaemic clamp technique in this model.

British Journal of Pharmacology (2005) 144, 308–316. doi:10.1038/sj.bjp.0706041