bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regionalization of DNA and protein synthesis in developing stages of the parasitic platyhelminth Echinococcus granulosus
Authors: Galindo M. , Paredes R. , Marchant C. , Miño V. , Galanti N. 
Published: September 2003

AbstractEchinococcus granulosus is a parasitic platyhelminth, which causes cystid hydatid disease, a major zoonosis involving canids as definitive hosts, and both human and herbivorous domestic animals as intermediate hosts. The disease is caused in intermediate hosts by hydatid cysts, formed upon ingestion of E. granulosus eggs excreted by canids. Protoscoleces, the developmental forms of the parasite infective to canids, are formed in the germinal cellular layer of hydatid cysts. We have found that protoscoleces develop from patches of proliferating cells present in the germinal layer of the hydatid cyst, while most of the other cells of the germinal layer are in a resting state. Further, patches of proliferating cells form buds, which elongate and develop a separate population of cycling cells. In these elongated buds, cell differentiation leads to the main structures of the protoscolex. Protein synthesis is very active among cells of early buds and coincides with their proliferating activity. By contrast, protein synthesis presents a much lower activity in the resting cells of the germinal layer surrounding the growing protoscoleces. In elongated buds at different stages of development, protein synthesis is found mainly close to cellular territories in which cell differentiation occurs. In free infective protoscoleces, cells in DNA synthesis are concentrated in the body of the larva while protein synthesis occurs in the entire larva. This is the first description of the regionalization of DNA and protein synthesis in developing stages of E. granulosus. J. Cell. Biochem. 90: 294–303, 2003. © 2003 Wiley‐Liss, Inc.
Role of MAPK phosphorylation in cytoprotection by pro‐vitamin C against oxidative stress‐induced injuries in cultured cardiomyoblasts and perfused rat heart
Authors: Eguchi Masahiro , Monden Kazuaki , Miwa Nobuhiko 
Published: September 2003

AbstractThe reactive oxygen species (ROS) are known to be generated upon post‐ischemic reperfusion (I/R) of the heart, and to injure cardiac muscle cells. The hydrogen peroxide‐induced mortality of rat cardiomyoblasts H2c9 was markedly inhibited by previous administration with auto‐oxidation‐resistant pro‐vitamin C, the 2‐O‐phosphorylated derivative (Asc2P) of ascorbic acid (Asc). The cytoprotection was partially counteracted by an inhibitor of MAPK (mitogen‐activated protein kinase) kinase (MEK) as shown by DNA strand cleavage assay and mitochondrial dehydrogenase assay. Immunostains indicated that phosphorylated MAPK increased in the hydrogen peroxide‐treated cardiomyoblasts, and that this action was moderately inhibited by Asc2P and restored nearly to the initial, pretreatment level by combined administration of the MEK inhibitor and Asc2P. The I/R‐induced cell injuries in perfused rat hearts as estimated by extracellular release of the cardiac enzyme CPK were inhibited by 2‐O‐α‐glucosylascorbic acid (Asc2G) and Asc, whereas the observed cytoprotection for the cardiomyoblasts was partially counteracted by the MEK inhibitor. The increase in phosphorylated MAPK in I/R‐operated hearts was moderately inhibited by pro‐vitamin C, but restored nearly to the normal non‐operated level by combined administration with the MEK inhibitor. This is in contrast to no alteration in levels of non‐phosphorylated MAPK for all the cases examined as shown by Western blots, consistent with results of immunostains for the cardiomyoblasts. The inhibitory effect of the MEK inhibitor on MAPK phosphorylation was, therefore, suggested to counteract the cytoprotective effects of pro‐vitamin C via a thorough interruption of the phosphorylated MAPK signaling pathway. This was not true of ROS‐related events; the scavenging effects of Asc2G and Asc on hydroxyl radicals generated from I/R‐operated heart were not affected by combined administration with the MEK inhibitor, as shown by the spin‐trapping DMPO‐based ESR method. J. Cell. Biochem. 90: 219–226, 2003. © 2003 Wiley‐Liss, Inc.
Fibroblast growth factor receptor‐1 mediates the inhibition of endothelial cell proliferation and the promotion of skeletal myoblast differentiation by SPARC: A role for protein kinase A
Authors: Motamed Kouros , Blake David J. , Angello John C. , Allen Benjamin L. , Rapraeger Alan C. , Hauschka Stephen D. , Sage E. Helene 
Published: September 2003

AbstractThe role of the matricellular protein SPARC (secreted protein, acidic and rich in cysteine) in modulation of vascular cell proliferation is believed to be mediated, in part, by its ability to regulate the activity of certain growth factors through direct binding. In this study, we demonstrate that SPARC does not bind to basic fibroblast growth factor (bFGF/FGF‐2) or interfere with complex formation between FGF‐2 and its high‐affinity FGF receptor‐1 (FGFR1), yet both native SPARC and a peptide derived from the C‐terminal high‐affinity Ca2+‐binding region of protein significantly inhibit ligand‐induced autophosphorylation of FGFR1 (>80%), activation of mitogen‐activated protein kinases (MAPKs) (>75%), and DNA synthesis in human microvascular endothelial cells (HMVEC) stimulated by FGF‐2 (>80%). We also report that in the presence of FGF‐2, a factor which otherwise stimulates myoblast proliferation and the repression of terminal differentiation, both native SPARC and the Ca2+‐binding SPARC peptide significantly promote (>60%) the differentiation of the MM14 murine myoblast cell line that expresses FGFR1 almost exclusively. Moreover, using heparan sulfate proteoglycan (HSPG)‐deficient myeloid cells and porcine aortic endothelial cells (PAECs) expressing chimeric FGFR1, we show that antagonism of FGFR1‐mediated DNA synthesis and MAPK activation by SPARC does not require the presence of cell‐surface, low‐affinity FGF‐2 receptors, but can be mediated by an intracellular mechanism that is independent of an interaction with the extracellular ligand‐binding domain of FGFR1. We also report that the inhibitory effect of SPARC on DNA synthesis and MAPK activation in endothelial cells is mediated in part (>50%) by activation of protein kinase A (PKA), a known regulator of Raf‐MAPK pathway. SPARC thus modulates the mitogenic effect of FGF‐2 downstream from FGFR1 by selective regulation of the MAPK signaling cascade. J. Cell. Biochem. 90: 408–423, 2003. © 2003 Wiley‐Liss, Inc.
Expression of procollagen C‐proteinase enhancer in cultured rat heart fibroblasts: Evidence for co‐regulation with type I collagen
Authors: Shalitin Noa , Schlesinger Hadassa , Levy Maurice J. , Kessler Efrat , Kessler‐Icekson Gania 
Published: September 2003

AbstractProcollagen processing by procollagen C‐proteinase (PCP) is an important step in collagen deposition. This reaction is stimulated by another glycoprotein, known as PCP enhancer. The objective of this study was to identify factors that regulate the expression of PCP enhancer in cardiac fibroblasts and examine possible correlation with collagen expression. Rat heart fibroblasts were cultured in the presence or absence of three known stimulators of collagen synthesis: ascorbic acid, TGF‐β, and aldosterone. The mRNA and protein levels of PCP enhancer and collagen type I were each assessed using Northern and Western blotting, respectively. Expression of PCP was assessed by RT‐PCR and its activity in the culture media was determined using radioactive procollagen as the substrate. The levels of PCP enhancer mRNA increased 1.5‐ to 2‐fold in response to ascorbate, TGF‐β, or aldosterone. This increase was paralleled by an up to fourfold increase in the level of the pro α1(I) collagen chain transcript and was accompanied by a marked increase in the levels of the respective proteins in the culture media. PCP activity in the culture media was also increased, apparently, without effect on its expression. These results indicate that expression of PCP enhancer in cultured rat heart fibroblasts is coordinated with that of collagen. The observed augmentation of PCP activity may be a consequence of the increase in the levels of PCP enhancer in the culture media. J. Cell. Biochem. 90: 397–407, 2003. © 2003 Wiley‐Liss, Inc.
Downregulation of inducible nitric oxide synthetase by neurotrophin‐3 in microglia
Authors: Tzeng Shun‐Fen , Huang Hsin‐Ying 
Published: September 2003

AbstractMicroglia activated after many neurological degeneration of the central nervous system (CNS) act as important regulators for neuropathogenesis in the injured CNS via producing proinflammatory mediators, such as nitric oxide (NO), TNF‐α, and IL‐1β. Neurotrophin‐3 (NT‐3) is a well‐known trophic factor for neural survival, development, and plasticity. Activated microglia are NT‐3‐producing cells in the injured CNS, and express its receptor‐TrkC. However, little is known about the effect of NT‐3 on activated microglia. In this study, pre‐treatment of a mouse microglial cell line, BV2, with NT‐3 for 24 h indicated that NT‐3 reduced the inducible form of NO synthase (iNOS), NO, and TNF‐α in BV2 stimulated with lipopolysaccharide (LPS). NT‐3 exerted less effect on the reduction of these proinflammatory mediators when it was added to BV2 cultures either simultaneously with LPS or post LPS treatment. These findings indicate that NT‐3 may serve as an anti‐inflammatory factor to suppress microglial activation. J. Cell. Biochem. 90: 227–233, 2003. © 2003 Wiley‐Liss, Inc.
Unusual atmospheric pressure chemical ionization conditions for detection of organic peroxides
Authors: Rondeau David , Vogel René , Tabet Jean‐Claude 
Published: September 2003

AbstractOrganic peroxides such as the cumene hydroperoxide I (Mr = 152 u), the di‐tert‐butyl peroxide II (Mr = 146 u) and the tert‐butyl peroxybenzoate III (Mr = 194 u) were analyzed by atmospheric pressure chemical ionization mass spectrometry using a water–methanol mixture as solvent with a low flow‐rate of mobile phase and unusual conditions of the source temperature (≤50 °C) and probe temperature (70–200 °C). The mass spectra of these compounds show the formation of (i) an [M + H]+ ion (m/z 153) for the hydroperoxide I, (ii) a stable adduct [M + CH3OH2]+ ion (m/z 179) for the dialkyl peroxide II and (iii) several protonated adduct species such as protonated molecules (m/z 195) and different protonated adduct ions (m/z 227, 389 and 421) for the peroxyester III. Tandem mass spectrometric experiments, exact mass measurements and theoretical calculations were performed for characterize these gas‐phase ionic species. Using the double‐well energy potential model illustrating a gas‐phase bimolecular reaction, three important factors are taken into account to propose a qualitative interpretation of peroxide behavior toward the CH3OH2+, i.e. thermochemical parameters ($\Delta H_{\rm reaction}^{\circ}$) and two kinetic factors such as the capture constant of the initial stable ion–dipole and the magnitude of the rate constant of proton transfer reaction into the loose proton bond cluster. Copyright © 2003 John Wiley & Sons, Ltd.
Electron ionization mass spectrometric study of monomeric models of O‐polysaccharides of Vibrio cholerae O:1, serotypes Ogawa and Inaba
Authors: Kováčik Vladimír , Pätoprstý Vladimír , Oksman Pentti , Mistrík Robert , Kováč Pavol 
Published: September 2003

AbstractFragmentation mechanisms of electron ionization (EI) mass spectrometry of the title compounds have been elucidated by high‐resolution (HR) mass spectrometric measurements of the elemental composition and measurements of the metastable transitions (B2/E, CID). The experimental results were interpreted with the help of Mass Frontier 3.0 software, which aided the elucidation of fragmentation mechanisms and helped to deduce structures of the ions formed. Characteristic under the conditions of EI‐MS measurement was the production of protonated adducts. Three distinct pathways observed include the formation of oxonium type ions, the conjugated transfer of electrons in the pyranose ring, and cleavage of the acylamide side chains. By applying the results obtained, the molecular mass, as well as the structures of both the saccharide and acylamide side chain involved in related substances, can be determined. Copyright © 2003 John Wiley & Sons, Ltd.
Role of opposite charges in protein electrospray ionization mass spectrometry
Authors: Šamalikova Maria , Grandori Rita 
Published: September 2003

AbstractThe conformation dependence of protein spectra recorded by electrospray ionization mass spectrometry (ESI‐MS) is an interesting and useful phenomenon, whose origin is still the object of debate. Different mechanisms have been invoked in the attempt to explain the lower charge state of folded versus unfolded protein ions in ESI‐MS, such as electrostatic repulsions, solvent accessibility, charge availability, and native‐like interactions. In this work we try to subject to direct experimental test the hypothesis that conformation‐dependent neutralization of charges with polarity opposite to the net charge of the protein ion could play a critical role in such an effect. We present results of time‐of‐flight nano‐ESI‐MS on the peptide angiotensin II, indicating that negative charges of carboxylate groups can contribute to spectra recorded in positive‐ion mode when stabilized by favorable electrostatic interactions, which is the central assumption of our hypothesis. Comparison of horse and spermwhale myoglobin (Mb) shows that changing the total number of basic residues within a given three‐dimensional structure shifts the charge‐state distribution (CSD) of the folded protein in positive‐ion mode. This result appears to be in contrast to models in which electrostatic repulsions or availability of charges in the ESI droplets represent the limiting factor for the ionization of folded protein ions in ESI‐MS. At the same time, it suggests a role of acidic residues in conformational effects in positive‐ion mode. Furthermore, an attempt is made to rationalize those cases in which, in contrast, the main charge state observed in ESI‐MS under non‐denaturing conditions deviates considerably from the net charge expected on the basis of the amino‐acid composition. These cases usually correspond to proteins with quite balanced content in basic and acidic residues, suggesting that this might be a factor influencing their charging behavior in ESI‐MS. Experiments on mutants of ribonuclease Sa (RNase Sa) reveal that progressively reducing the excess of acidic residues, replacing them by lysine, causes almost no shift in the spectrum of the folded protein in negative‐ion mode. Analogously, variants with an excess of three or five basic residues give similar spectra in positive‐ion mode. These results indicate a lower limit to the extent of ionization observable by ESI‐MS (6− or 8+ in the case of RNase Sa in water). Below such limit of net charge, changes in the relative amount of ionizable side chains do not affect the qualitative features of the observed CSDs. A progressive loss of signal intensity caused by the mutations in negative‐ion mode suggests that low charge states might also be counterselected, even within the m/z range theoretically accessible to the instrument. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of the quantitativeness of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry using an equimolar mixture of uniform poly(ethylene glycol) oligomers
Authors: Shimada Kayori , Nagahata Ritsuko , Kawabata Shin‐ichiro , Matsuyama Shigetomo , Saito Takeshi , Kinugasa Shinichi 
Published: September 2003

AbstractQuantitativeness of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) was elucidated using an equimolar mixture of uniform poly(ethylene glycol) (PEG) oligomers with no molecular weight distributions. Uniform PEG oligomers with degrees of polymerization n = 6–40 were separated from commercial PEG samples by preparative super‐critical fluid chromatography. MALDI‐TOF mass spectra of an equimolar mixture of the uniform PEG oligomers were recorded by adding a mixture of 2,5‐dihydroxybenzoic acid as a matrix reagent and four chlorinated salts, i.e. LiCl, NaCl, KCl and RbCl. Remarkable non‐quantitative effects were observed in the MALDI‐TOF mass spectra in both the lower and higher molecular mass regions. At higher molecular masses greater than about 103, PEG oligomers with larger molecular mass yielded lower spectral intensities irrespective of the species of adduct cations and higher laser powers induced larger decreases in mass spectral intensities with the increase in their molecular masses. On the other hand, in the lower molecular mass region, less than about 103, the observed non‐quantitative effect greatly depends on the species of adduct cations, indicating that the stability of the PEG–cation complex affects the MALDI‐TOF mass spectral intensities of uniform PEG oligomers. Copyright © 2003 John Wiley & Sons, Ltd.
Post‐translational modification of Rhodococcus R312 and Comamonas NI1 nitrile hydratases
Authors: Stevens Julie M. , Belghazi Maya , Jaouen Maryse , Bonnet Didier , Schmitter Jean‐Marie , Mansuy Daniel , Sari Marie‐Agnès , Artaud Isabelle 
Published: September 2003

AbstractNitrile hydratases (NHases) are industrially significant iron‐ and cobalt‐containing enzymes used in the large‐scale synthesis of acrylamide. Previous reports have shown that the active site peptides of NHases are post‐translationally modified by oxidation of cysteine residues, and that these modifications are essential for catalysis. We report mass spectrometric evidence of the oxidation states of the active site cysteines in the iron coordination spheres of two iron‐containing nitrile hydratases, namely R312 NHase from Rhodococcus rhodochrous strain R312 and NI1 NHase from Comamonas testosteroni. At least one of these cysteines is oxidised to a sulfinic acid (SO2H) and there is also evidence suggesting an additional oxidation to a sulfenic acid (SOH). This is the first evidence for the presence of these oxidation states for full‐length NHases and for Fe‐NHases from different microorganisms. The presence of these covalent modifications was confirmed by performing mass spectrometry on the active site peptide of R312 NHase, under native, reduced and carboxymethylated conditions. We also show the nitrosylation of the iron by mass spectrometry, as well as the release of NO by photoirradiation. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of aconitine‐type alkaloids in the flowers of Aconitum kusnezoffii by electrospray ionization tandem mass spectrometry
Authors: Wang Yong , Song Fengrui , Xu Qingxuan , Liu Zhiqiang , Liu Shuying 
Published: September 2003

AbstractThe fragmentation mechanism of aconitine‐type alkaloids in the flowers of Aconitum kusnezoffii (FAK) was investigated using electrospray ionization tandem mass spectrometry (ESI‐MSn) firstly. The analysis of the collision‐induced dissociation (CID) spectra of three purified aconitine standards and six previously reported aconitines indicated that the fragmentation of the protonated aconitines at low‐energy CID follows a similar pathway. The elimination of a C8‐substituent such as an acetic acid or a fatty acid is the dominant fragmentation mode in MS2. Successive losses of CH3COOH, CH3OH, H2O, BzOH, and CO are the main fragmentation pathways of aconitine‐type alkaloids in MS3 spectra. Based on these features, a rapid method for the direct detection and characterization of alkaloids from an ethanolic extract of FAK is described. All the known aconitum alkaloids are detected and a series of lipo‐aconitines has been found for the first time in this plant. Copyright © 2003 John Wiley & Sons, Ltd.
Gas‐phase investigation of Pd(II)‐alanine complexes with small native and derivatized peptides containing histidine
Authors: Anbalagan V. , Van Stipdonk M. J. 
Published: September 2003

AbstractWe report here the generation of gas‐phase complexes containing Pd(II), a ligand (deprotonated alanine, A−), and/or N‐terminus derivatized peptides containing histidine as one of the amino acids. The species were produced by electrospray ionization, and their gas‐phase reactions were investigated using ion‐trap tandem mass spectrometry. Pd(II) forms a stable diaqua complex in the gas phase of the formula, [Pd(A−) (H2O)2]+, (where A− = deprotonated alanine) along with ternary complexes containing A− and peptide. The collision‐induced dissociation (CID) patterns of the binary and ternary complexes were investigated, and the dissociation patterns for the ternary complexes suggest that: (a) the imidazole ring of the histidine side group may be the intrinsic binding site of the metal ion, and (b) the peptides fragment primarily by cleavage of the amide bond to the C‐terminal side of the histidine residues. These observations are in accord with previous solution‐state studies in which Pd(II) was shown to cause hydrolysis of an amide bond of a peptide at the same position. Copyright © 2003 John Wiley & Sons, Ltd.
New designer drug 1‐(3‐trifluoromethylphenyl) piperazine (TFMPP): gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry studies on its phase I and II metabolism and on its toxicological detection in rat urine
Authors: Staack Roland F. , Fritschi Gieselher , Maurer Hans H. 
Published: September 2003

AbstractStudies are described on the phase I and II metabolism and the toxicological analysis of the piperazine‐derived designer drug 1‐(3‐trifluoromethylphenyl)piperazine (TFMPP) in rat urine using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). The identified metabolites indicated that TFMPP was extensively metabolized, mainly by hydroxylation of the aromatic ring and by degradation of the piperazine moiety to N‐(3‐trifluoromethylphenyl)ethylenediamine, N‐(hydroxy‐3‐trifluoromethylphenyl)ethylenediamine, 3‐trifluoromethylaniline, and hydroxy‐3‐trifluoromethylaniline. Phase II reactions included glucuronidation, sulfatation and acetylation of phase I metabolites. The authors' systematic toxicological analysis (STA) procedure using full‐scan GC/MS after acid hydrolysis, liquid‐liquid extraction and microwave‐assisted acetylation allowed the detection of TFMPP and its above‐mentioned metabolites in rat urine after single administration of a dose calculated from the doses commonly taken by drug users. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of TFMPP in human urine. Copyright © 2003 John Wiley & Sons, Ltd.
Atmospheric pressure chemical ionization mass spectrometry and in‐source fragmentation of lutein esters
Authors: Tian Qingguo , Duncan Christine J. G. , Schwartz Steven J. 
Published: September 2003

AbstractNegative‐ion atmospheric pressure chemical ionization (APCI) mass spectrometry and in‐source collisionally induced dissociation (CID) were employed to obtain structural information of lutein esters from marigold extract. Both molecular ions and structurally significant fragments corresponding to the loss of fatty acids were observed in high abundance in the current study. Six lutein diesters including lauroylmyristoyl‐lutein (LML), dimyristoyl‐lutein (dML), myristoylpalmitoyl‐lutein (MPL), dipalmitoyl‐lutein (dPL), palmitoylstearoyl‐lutein (PSL) and distearoyl‐lutein (dSL) were characterized in a marigold flower extract. Breakdown curves (plots of relative ion abundance vs. internal energy) of three lutein diesters were established by monitoring the relative ion abundance of molecular and fragment ions at different cone voltages during negative‐ion APCI‐LC/MS analysis. Copyright © 2003 John Wiley & Sons, Ltd.