bluuebunny/crossref_metadata_2025_split huggingface dataset:
Can radical cations of the constituents of nucleic acids be formed in the gas phase using ternary transition metal complexes?
Authors: Wee Sheena , O'Hair Richard A. J. , McFadyen W. David 
Published: June 2005

AbstractElectrospray ionization (ESI) tandem mass spectrometry (MS/MS) of ternary transition metal complexes of [M(L3)(N)]2+ (where M = copper(II) or platinum(II); L3 = diethylenetriamine (dien) or 2,2′:6′,2″‐terpyridine (tpy); N = the nucleobases: adenine, guanine, thymine and cytosine; the nucleosides: 2′deoxyadenosine, 2′deoxyguanosine, 2′deoxythymine, 2′deoxycytidine; the nucleotides: 2′deoxyadenosine 5′‐monophosphate, 2′deoxyguanosine 5′‐monophosphate, 2′deoxythymine 5′‐monophosphate, 2′deoxycytidine 5′‐monophosphate) was examined as a means of forming radical cations of the constituents of nucleic acids in the gas phase. In general, sufficient quantities of the ternary complexes [M(L3)(N)]2+ could be formed for MS/MS studies by subjecting methanolic solutions of mixtures of a metal salt [M(L3)X2] (where M = Cu(II) or Pt(II); L3 = dien or tpy; X = Cl or NO3) and N to ESI. The only exceptions were thymine and its derivatives, which failed to form sufficient abundances of [M(L3)(N)]2+ ions when: (a) M = Pt(II) and L3 = dien or tpy; (b) M = Cu(II) and L3 = dien. In some instances higher oligomeric complexes were formed; e.g., [Pt(tpy)(dG)n]2+ (n = 1–13). Each of the ternary complexes [M(L3)(N)]2+ was mass‐selected and then subjected to collision‐induced dissociation (CID) in a quadrupole ion trap. The types of fragmentation reactions observed for these complexes depend on the nature of all three components (metal, auxiliary ligand and nucleic acid constituent) and can be classified into: (i) a redox reaction which results in the formation of the radical cation of the nucleic acid constituent, N+.; (ii) loss of the nucleic acid constituent in its protonated form; and (iii) fragmentation of the nucleic acid constituent. Only the copper complexes yielded radical cations of the nucleic acid constituent, with [Cu(tpy)(N)]2+ being the preferred complex due to suppression, in this case, of the loss of the nucleobase in its protonated form. The yields of the radical cations of the nucleobases from the copper complexes follow the order of their ionization potentials (IPs): G (lowest IP) > A > C > T (highest IP). Sufficient yields of the radical cations of each of the nucleobases allowed their CID reactions (in MS3 experiments) to be compared to their even‐electron counterparts. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of bufadienolides in the Chinese drug ChanSu by high‐performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry
Authors: Ye Min , Guo De‐an 
Published: June 2005

AbstractThe qualitative analysis of bufadienolides in the Chinese drug ChanSu was performed using high‐performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (APCI‐MS/MS). Bufadienolides are the major bioactive constituents of ChanSu, which is used to treat heart failure and cancer in traditional Chinese medicine. The APCI‐MS fragmentation behavior of bufadienolides was studied. For bufadienolides with only hydroxyl substituents, the fragmentation was characterized by successive eliminations of H2O and CO molecules, and the profile of MS/MS product ions was correlated with the number of hydroxyl groups. If a C‐16 acetoxyl group was present, the fragmentation of [M+H]+ ions was triggered by initial loss of 60 Da (HOAc). The elimination of CO was significant for bufadienolides with a 19‐formyl group, and the 19‐hydroxyl group could be characterized by the loss of 30 Da (HCHO). These fragmentation rules were applied to the identification of bufadienolides in a methanolic extract of ChanSu, which was separated on a C18 column with gradient elution. A total of 35 bufadienolides were identified, including four new constituents. The method established here facilitated the convenient and rapid quality control of ChanSu crude drug and its pharmaceutical preparations. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of organochlorines in harbor seal (Phoca vitulina) tissue samples from Alaska using gas chromatography/ion trap mass spectrometry by an isotopic dilution technique
Authors: Wang Dongli , Atkinson Shannon , Hoover‐Miller Anne , Li Qing X. 
Published: June 2005

AbstractA gas chromatography/ion trap mass spectrometry (GC/ITMS) method was developed for the determination of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in harbor seal (Phoca vitulina) tissues. Tissue samples were homogenized, lyophilized and fortified with 13C‐PCBs 28, 123, 169 and 170, and then extracted with an accelerated solvent extractor with a mixture of hexane and methylene chloride (1:1, v/v). After lipid removal using a 40% H2SO4‐modified silica gel column, all organochlorines were collected in one fraction and further fractionated with an activated carbon/silica gel (1:20) column into a first fraction containing OCPs, non‐coplanar PCBs and 13C‐PCBs 28, 123 and 170, and a second containing PCNs, coplanar PCBs and 13C‐PCB 169. Prior to GC/MS/MS analysis, 13C‐PCB 169 was added into the first fraction as an injection standard and 13C‐PCB 170 into the second fraction to calibrate the recoveries of the fortified internal standards. This method can effectively eliminate matrix interferences, and has high selectivity and sensitivity. Recoveries averaged 45–86% for OCPs with relative standard deviations (RSDs) of 2–14%, 52–137% for PCBs with RSDs of 3–29% and 36–152% for PCNs with RSDs of 7–29% from lard and chicken heart samples, which were used as alternative matrices to harbor seal samples in recovery studies. The limits of detection for OCPs, PCBs and PCNs were 0.7–1.9, 1.5–8.9 and 0.5–10 pg/g dry weight, respectively. This method can be used to analyze OCPs, PCBs and PCNs in harbor seal blubber, liver and kidney samples. Copyright © 2005 John Wiley & Sons, Ltd.
Study of metal complexes of a tripodal hydroxypyridinone ligand by electrospray tandem mass spectrometry
Authors: Budimir Natali , Fournier Françoise , Bailly Théodorine , Burgada Ramon , Tabet Jean‐Claude 
Published: June 2005

AbstractThe tripodal ligand N,N,N‐tris[(1,hydroxy‐2‐pyridinon‐6‐yl)amide]propylamine was synthesized. It is composed of an anchor (nitrogen atom), a functional group (hydroxamate), and also a spacer of variable length defined by the number of methylene groups linking the anchor and the functional group. The characterization of this ligand in the presence of several divalent metal cations (FeII, MnII, CoII and CuII), performed by electrospray ionization mass spectrometry (ESI‐MS and ESI‐MS/MS), allowed elucidation of oxidation states and also of different fragmentation patterns. The importance of the spacer length was studied in the case of the iron binary complex by comparing this ligand with another with a shorter spacer. In this way the stabilizing conditions, in which hydrogen bonds are implicated, were clarified. Copyright © 2005 John Wiley & Sons, Ltd.
New conditions for matrix‐assisted laser desorption/ionization mass spectrometry of native bacterial R‐type lipopolysaccharides
Authors: Sturiale Luisa , Garozzo Domenico , Silipo Alba , Lanzetta Rosa , Parrilli Michelangelo , Molinaro Antonio 
Published: June 2005

AbstractA new sample preparation method for matrix‐assisted laser desorption/ionization (MALDI) analysis of native rough‐type lipopolysaccharides (R‐type LPSs) is presented. In our MALDI mass spectra, besides the [MH]− ions, abundant ions originating from the cleavage between the 3‐deoxy‐D‐manno‐oct‐2‐ulosonic acid (Kdo) unit and the lipid A moiety are always present, giving important pieces of information about the structure of the molecules analyzed. Remarkably, in most cases, the comparison of the MALDI mass spectra of the intact R‐type LPS with the O‐deacylated one allowed us to obtain the structure of the lipid A moiety. Copyright © 2005 John Wiley & Sons, Ltd.
Mono‐ and diiodocyclophosphamide as possible internal standards for cyclophosphamide quantification: characterization by ion trap multi‐stage mass spectrometry and effects of iodine‐chlorine substitution on the fragmentation pattern
Authors: Castiglia L. , Miraglia N. , Pieri M. , Genovese G. , Simonelli A. , Basilicata P. , Sannolo N. , Acampora A. 
Published: June 2005

AbstractHospital personnel involved in antineoplastic drug preparation and administration to patients are exposed to large amounts of these drugs. Labour legislation indicates the necessity of planning monitoring strategies aimed at prevention and/or reduction of drug exposure. Monitoring strategies consist of quantitative determinations of indicators, present in environmental and biological matrices. Among the antineoplastic drugs widely used, cyclophosphamide (CP) has been identified as a suitable indicator of potential exposure to mixtures of antineoplastic drugs. Many literature methods for quantitative analysis of CP involve either liquid (LC) or gas chromatography (GC) with mass spectrometry (MS), both of which require use of a suitable internal standard. The present work focuses on the synthesis of mono‐ and diiodocyclophosphamide (CPI and CPI2) to be used as internal standard. These compounds were analyzed by GC/EI‐MS/MS and LC/ESI‐MSn using ion trap mass spectrometry. The product ion mass spectra are interpreted in terms of proposed structures of fragment ions. Iodine‐chlorine substitution resulted in a weakening of the carbon–halogen bond with a noteworthy influence on the ion fragmentation processes. The proposed suitability of CPI and CPI2 as internal standards was based on similarities to CP as regards ionization and fragmentation processes. The results obtained suggest that CPI could be used as internal standard for CP quantification by LC/ESI‐MS/MS, and CPI2 for GC/EI‐MS/MS analyses. Copyright © 2005 John Wiley & Sons, Ltd.
Characterisation via electrospray ionisation multistage mass spectrometry of three related series of nitrido technetium complexes containing phosphinothiolate and dithiocarbamate ligands
Authors: Tubaro Michela , Traldi Pietro , Bolzati Cristina , Tisato Francesco , Refosco Fiorenzo , Benini Elisa , Cavazza‐Ceccato Mario 
Published: June 2005

AbstractNine nitrido technetium compounds comprising bis‐substituted Tc(N)(PS)2 (1–4) (PS = bidentate phosphinothiolate ligands) and Tc(N)(dtc)2 (5, 6) derivatives (dtc = bidentate dithiocarbamate), and mixed‐ligand Tc(N)(PS)(dtc) (7–9) species, were subjected to electrospray ionisation mass spectrometry and MSn experiments. Bis‐substituted phosphinothiolato complexes 1–4 lead to the straightforward formation of dinuclear species reasonably originating from proton bound dimers. These dinuclear species do not show, under collisionally induced fragmentation processes, the formation of monomeric units but cleavages related to the ligand framework, thereby proving the high stability of the [TcH+Tc] bond. Bis‐dithiocarbamate compounds 5 and 6 show, instead, abundant [M+H]+, [M+Na]+ and [2M+Na]+ ions, and their collisionally induced fragmentations are highly favoured with cleavages related to the CN and CS bonds. During these processes, the coordination of a water molecule to [MH–L]+ product ions is observed, as proved by the collisionally induced H2O loss detected for this species. Mixed‐ligand compounds 7 and 8 show the protonated molecules and Na+‐cationised ions with fragmentation processes related to the dithiocarbamate moiety. This behaviour indicates that coordination of ether‐ and ester‐substituted dithiocarbamates to the [Tc  N] group is weaker than that of phosphinothiolates. Conversely, diethyldithiocarbamate inserted in mixed complex 9 enhances both CN and TcS bonds, and fragmentation processes suggest that metal‐phosphinothiolate and metal‐dithiocarbamate show comparable strength. Copyright © 2005 John Wiley & Sons, Ltd.
Negative‐ion electrospray ionization mass spectrometry of N‐benzyloxycarbonyl‐protected 1‐substituted and cyclic taurines
Authors: Xu Jiaxi , Ma Yuan , Xu Shu , Zhao Yufen 
Published: June 2005

AbstractThe negative‐ion mass spectrometric behavior of N‐benzyloxycarbonyl‐protected 1‐substituted and cyclic taurines has been investigated under electrospray ionization conditions. Their fragmentation pathways are proposed and supported by collisionally activated dissociation product‐ion spectrometry. The deprotonated substituted taurines preferentially eliminate a molecule of benzyl alcohol to yield isocyanato‐sulfonate ions, which further generate alkene‐2‐sulfonate ions by loss of isocyanic acid. The isocyanato‐sulfonate ions of 1‐substituted taurines could further generate aziridine‐2‐sulfonate ion via ring rearrangements by loss of CO plus benzyne and carbene moieties, respectively, while the isocyanato‐sulfonate ions of cyclic taurines could further give rise to cycloalkene anion radicals. An obvious substituent effect on the fragmentations of the title compounds was observed. Copyright © 2005 John Wiley & Sons, Ltd.
13C‐Isotope ratio mass spectrometry as a potential tool for the forensic analysis of white architectural paint: a preliminary study
Authors: Reidy L. J. , Meier‐Augenstein W. , Kalin R. M. 
Published: June 2005

AbstractPaints have a dual role in society, to protect materials from environmental agents such as ultraviolet light, moisture and oxygen, and to make painted materials look more attractive. Variability in paint samples is often due to binder and pigment type within the sample. The most common resin used in decorative paints is drying oil alkyd resin, which incorporates soybean oil and vinyl acrylic based latexes. Traditional analytical methods used by forensic scientists may be able to say whether two paint samples are indistinguishable but cannot conclusively say that they both originate from the same source. To find out if isotopic composition can provide an added dimension of information, 28 different white architectural paints were analysed for 13C abundance using isotope ratio mass spectrometry. In addition, variations in application, drying time and thickness were also investigated to assess the discriminatory power of 13C data from white paints with an unknown history. Preliminary results indicate that this method could aid screening of paint samples. Copyright © 2005 John Wiley & Sons, Ltd.
The host environment drives HIV‐1 fitness
Authors: van Opijnen Tim , Berkhout Ben 
Published: June 2005

AbstractViral fitness is defined by the ability of an individual genotype to produce infectious progeny in a specific environment. For HIV the environment is never constant but rather fluctuates in time and space. For instance, environmental factors that determine viral fitness during transmission from host to host are different to the pressures from either cytotoxic T‐lymphocytes (CTLs) or antiviral drugs. Consequently, viral fitness is highly dependent on the environment and the accurate determination of this value therefore depends strongly on the chosen environmental setting. This review describes how the host environment imposes selective pressures on the virus that shape its genotype and fitness. The most important environments that the virus encounters throughout its life cycle and during natural infection are discussed. In order of appearance, CTLs are discussed, followed by neutralising antibodies and antiretroviral drug treatment. It then goes on to describe receptor molecules that mediate viral entry and intracellular restriction factors, which represent selective pressures that are present directly from the start of a natural infection. It concludes by discussing the complexity of viral fitness and how an accurate measure of viral fitness eventually may, for example, contribute to the improvement of antiretroviral therapy or help in the formulation of an optimal vaccination strategy. Copyright © 2005 John Wiley & Sons, Ltd.
Time course of localization for a repeatedly flashing stimulus presented at perisaccadic timing
Authors: Watanabe Junji , Maeda Taro , Tachi Susumu 
Published: June 2005

AbstractWhen a light spot is flashed repeatedly during saccade, a dotted line called a phantom array (PA) is perceived. When light spots are placed on a vertical line and the flashing pattern is changed quickly during saccade, the flashing pattern is expanded to a spatial pattern by the effect of eye movement, and a two‐dimensional image is perceived. The authors have proposed a visual information presentation method based on this phenomenon. A crucial issue in information presentation by this method is the time relation between the perceived PA and the eye movement. Consequently, this study examines the time relation between the perception and the eye movement. The time course of perceived position for repeatedly flashing stimulus is investigated by presenting light spots in the vertical position. It is found that the locus of the perceived light spot starts to curve at the start of saccade in the direction opposite to the saccade, and returns to the vertical direction when the saccade ends. It differs from the locus of the light spot which is expected in accordance with cancellation theory. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(9): 77–86, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10690
Chip size and performance evaluations of shared cache for on‐chip multiprocessor
Authors: Sasaki Takahiro , Inoue Tomohiro , Omori Nobuhiko , Hironaka Tetsuo , Mattausch Hans J. , Koide Tetsushi 
Published: June 2005

AbstractRecent semiconductor technology has made on‐chip multiprocessors with several CPUs and cache memories on a single chip a realistic possibility. Generally, conventional multiprocessor systems with shared memory offer a simple programming model, but need a cache coherency mechanism that may become a system bottleneck. Furthermore, the same data may be cached on two or more caches, which prevents effective cache utilization. The multiport cache is one solution, but when using the conventional multiport memory architecture, the chip size of the multiport cache will increase in proportion to the square of the number of ports. On the other hand, with our proposed hierarchical multiport memory architecture, multiport memory can be implemented with a smaller chip size than by the conventional methods. This paper proposes the shared cache with a hierarchical multiport memory architecture that does not need a coherency mechanism. This paper also presents the results of performance evaluations and chip size estimations. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(9): 1–13, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20244
The factorial structure of the GHQ‐12
Authors: Vanheule Stijn , Bogaerts Stefan 
Published: June 2005

AbstractThis paper studies the factorial structure of the 12‐item version of the General Health Questionnaire (GHQ‐12), Dutch translation, in a large Belgian sample (n = 9442) that is representative of the general population. Data was collected from the 2001 Belgian Health Interview Survey. In total, 11 factor‐structure models are tested by means of confirmatory factor analysis. Two models, a two‐factorial model without cross‐loadings and a three‐factorial model with cross‐loadings, prove to have acceptable model‐fit. Given parsimony and the uni‐dimensionality of the subscales, the authors prefer the two‐factorial model over the three‐factorial one. In a next step, it is examined whether a general, second‐order factor can be seen underlying both the two‐ and three‐factorial models. This, however, was only true for the three‐factorial model. Based on correlations with other scales (the revised Symptom Checklist 90, SCL‐90‐R; the MOS Social Support Survey, MOS‐SSS) and a variable on social contacts, the authors suggest that the ‘social dysfunction’ subscale be renamed ‘dysfunction’. Copyright © 2005 John Wiley & Sons, Ltd.
Methylphenidate analogs with behavioral differences interact differently with arginine residues on the dopamine transporter in rat striatum
Authors: Volz Trent J. , Bjorklund Nicole L. , Schenk James O. 
Published: June 2005

AbstractThe methylphenidate analogs N‐methyl‐4‐methyl‐methylphenidate and N‐benzylmethylphenidate are believed to interact differently with the dopamine transporter (DAT) in vitro and in vivo. Herein, we report that methylphenidate and N‐methyl‐4‐methyl‐methylphenidate, but not N‐benzylmethylphenidate, protect the rat striatal DAT from the arginine‐selective chemical modifying agent, phenylglyoxal. This suggests that methylphenidate and N‐methyl‐4‐methyl‐methylphenidate, but not N‐benzylmethylphenidate, interact with the guanidine groups of arginine residues in the DAT of rat striatum. This differential interaction may, at least in part, explain the in vitro and in vivo differences between N‐methyl‐4‐methyl‐methylphenidate and N‐benzylmethylphenidate. Synapse 57:175–178, 2005. © 2005 Wiley‐Liss, Inc.
Metabotropic glutamate receptor protein expression in the prefrontal cortex and striatum in schizophrenia
Authors: Gupta Daya S. , McCullumsmith Robert E. , Beneyto Monica , Haroutunian Vahram , Davis Kenneth L. , Meador‐Woodruff James H. 
Published: June 2005

AbstractWe investigated the expression of metabotropic glutamate receptors (mGluR) in the prefrontal cortex (PFC) and striatum in schizophrenia. mGluRs modulate the release and reuptake of synaptic glutamate and mediate some molecular correlates of neuroplasticity, including long‐term potentiation. The mGluRs are expressed widely in the PFC and striatum, regions often implicated in the pathophysiology of schizophrenia. Thus, we hypothesized that abnormal expression of mGluRs might contribute to glutamatergic dysfunction observed in the PFC and striatum in schizophrenia. Accordingly, we measured the expression of metabotropic glutamate receptors (mGluRs) in Brodmann areas 9, 11, 32, and 46 in the prefrontal cortex (PFC) and the caudate, putamen, and nucleus accumbens in schizophrenia (16 cases, 9 controls) by Western blot analysis. We found an increase in the expression of mGluR1a and mGluR2/3 immunoreactivity in the PFC in schizophrenia, while no changes in the expression of mGluR4a or mGluR5 were detected in this region. In the striatum we found no changes in the expression of any of the mGluRs studied. These results suggest that alterations of mGluR1a and mGluR2/3 expression in the PFC may contribute to the pathophysiology of schizophrenia, and support targeting these receptors for the generation of novel treatment modalities for this disabling illness. Synapse 57:123–131, 2005. © 2005 Wiley‐Liss, Inc.