Showing papers by "Aix-Marseille University published in 1998"
TL;DR: The mechanism of superoxide generation by endothelial nitric oxide synthase (eNOS) was investigated by the electron spin resonance spin-trapping technique using 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide as discussed by the authors.
Abstract: The mechanism of superoxide generation by endothelial nitric oxide synthase (eNOS) was investigated by the electron spin resonance spin-trapping technique using 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide. In the absence of calcium/calmodulin, eNOS produces low amounts of superoxide. Upon activating eNOS electron transfer reactions by calcium/calmodulin binding, superoxide formation is increased. Heme-iron ligands, cyanide, imidazole, and the phenyl(diazene)-derived radical inhibit superoxide generation. No inhibition is observed after addition of l-arginine, NG-hydroxy-l-arginine, l-thiocitrulline, and l-NG-monomethyl arginine to activated eNOS. These results demonstrate that superoxide is generated from the oxygenase domain by dissociation of the ferrous–dioxygen complex and that occupation of the l-arginine binding site does not inhibit this process. However, the concomitant addition of l-arginine and tetrahydrobiopterin (BH4) abolishes superoxide generation by eNOS. Under these conditions, l-citrulline production is close to maximal. Our data indicate that BH4 fully couples l-arginine oxidation to NADPH consumption and prevents dissociation of the ferrous–dioxygen complex. Under these conditions, eNOS does not generate superoxide. The presence of flavins, at concentrations commonly employed in NOS assay systems, enhances superoxide generation from the reductase domain. Our data indicate that modulation of BH4 concentration may regulate the ratio of superoxide to nitric oxide generated by eNOS.
1,433 citations
TL;DR: The principles and practice of sampling are described in relation to the main habitat types encountered in Europe, and it is hoped that these provide a framework that can be adapted to most river types in Europe.
Abstract: Many methods for using diatoms for routine monitoring of water quality have been developed in Europe and, in some countries, these are being used to enforce environmental legislation. In order to facilitate their wider use, particularly with respect to European Union legislation, steps are being taken to harmonize methodology. In this paper, the principles and practice of sampling are described in relation to the main habitat types encountered in Europe. Although details of methods and sampling programmes have to be tailored to particular circumstances and the overall objectives of the monitoring, a number of generalizations can be made. Where available, rocks and other hard surfaces are the preferred substrates and methods for sampling these are described. If such substrata are not available, then introduced ('artificial') substrata have many applications. Various types of introduced substrata can be used successfully, so long as some basic precautions are described. Other types of substrata such as macrophytes and macroalgae may also be useful under certain circumstances, although there is less consensus in the literature on the most appropriate methods, and of the validity of comparisons between indices computed from epiphytic and epilithic communities. When designing surveys, it is recommended that as far as possible, extremes of non-water quality factors (e.g. shade, current speed, etc) are avoided, unless these are characteristic of the system under investigation. Detailed guidelines for sampling epilithon are described. Along with the recommendations for sampling other substrata, it is hoped that these provide a framework that can be adapted to most river types in Europe.
442 citations
TL;DR: In this paper, an unusual inflammatory myopathy characterized by an infiltration of non-epithelioid histiocytic cells has been recorded with increasing frequency in the past 5 years in France.
208 citations
TL;DR: This article used the alkenone method to estimate sea surface temperatures and focus their work on deep-sea sediments recovered from the tropical Indian Ocean during the last glacial cycle (0−150kyr BP).
181 citations
TL;DR: Findings show that, in HT29 cells, both Cdx1 and Cdx2 genes must be expressed to reduce tumorigenic potential, to increase sensitivity to apoptosis, and to reduce cell migration, suggesting that the two genes control the normal phenotype by independent pathways.
176 citations
TL;DR: A program for the identification of gene symbols and names inside sentences has been devised, made up of a series of sieves of different natures, lexical, morphological and semantic, to distinguish among the words of a sentence those which can only be potential gene symbols or names.
Abstract: Gathering data on molecular interactions to be fed into a specialized database has motivated the development of a computer system to help extracting pertinent information from texts, relying on advanced linguistic tools, completed with object-oriented knowledge modeling capabilities. As a first step toward this challenging objective, a program for the identification of gene symbols and names inside sentences has been devised. The main difficulty is that these names and symbols do not appear to follow construction rules. The program is thus made up of a series of sieves of different natures, lexical, morphological and semantic, to distinguish among the words of a sentence those which can only be potential gene symbols or names. Its performance has been evaluated, in terms of coverage and precision ratios, on a corpus of texts concerning D. melanogaster for which the list of names of known genes is available for checking.
162 citations
Centre national de la recherche scientifique1, University of Paris2, International Agency for Research on Cancer3, Aix-Marseille University4, Lille University of Science and Technology5, Centre Hospitalier Universitaire de Grenoble6, University of Angers7, Institut Gustave Roussy8, Harvard University9, Claude Bernard University Lyon 110
TL;DR: It is demonstrated that HPT could be an early component of the disease and provided the first estimate of age-specific and mutation-specific HPT penetrance in individuals with mutations of codon 634 of the RET proto-oncogene.
Abstract: Germline mutations of the RET proto-oncogene are responsible for multiple endocrine neoplasia type 2, including multiple endocrine type 2A (MEN 2A), type 2B (MEN 2B), and familial medullary thyroid carcinoma. The relationship between specific mutations and syndromic features has been established. In particular, the risk for pheochromocytoma and hyperparathyroidism (HPT) in MEN 2A patients is clearly associated with the presence of the RET mutation at a specific position, i.e. at codon 634. Also, a correlation between a specific mutation, C634R, and the development of HPT has been suggested but is still controversial. To further investigate the relationship between specific mutations of codon 634 and the development of HPT, we studied a population of 188 individuals, carrying mutations at codon 634, namely C634R (65 patients belonging to 10 families), C634Y (80 patients belonging to 11 families), or the less frequent codon 634 mutations [i.e. C634S, C634F, C634G, or C634W (43 patients belonging to 9 famili...
159 citations
TL;DR: Xenopus Brachyury directly regulates expression of eFGF by binding to an element positioned approximately 1 kb upstream of the eF GF transcription start site, which comprises half of the palindromic sequence previously identified by binding site selection.
Abstract: Brachyury is a member of the T-box gene family and is required for formation of posterior mesoderm and notochord during vertebrate development. The ability of Brachyury to activate transcription is essential for its biological function, but nothing is known about its target genes. Here we demonstrate that Xenopus Brachyury directly regulates expression of eFGF by binding to an element positioned approximately 1 kb upstream of the eFGF transcription start site. This site comprises half of the palindromic sequence previously identified by binding site selection and is also present in the promoters of the human and mouse homologues of eFGF.
147 citations
TL;DR: The chemistry of borane (BH 3 ) complexes of tricoordinated phosphorus compounds is reviewed in this paper, including the preparation, coordination chemistry, reactivity and synthetic applications.
121 citations
99 citations
TL;DR: Genetic comparisons of the 16S rRNA, rompA, gltA and the 17 kDa antigen genes with the other SFG rickettsiae confirmed the phylogenetic distance between R. honei and the previously described species.
Abstract: The name Rickettsia honei, strain RBT, has been proposed for a unique spotted fever group (SFG) agent which is pathogenic for humans. This agent has previously been compared to the other SFG agents and was shown to be distinct in protein structure by SDS-PAGE and by immunoblotting. Genetic comparisons of the 16S rRNA, rompA, gltA and the 17 kDa antigen genes with the other SFG rickettsiae confirmed the phylogenetic distance between R. honei and the previously described species. Genetically, Rickettsia honei is more closely related to the Thai tick typhus (TT-118) rickettsia than to any other member of the SFG. Indeed, it is proposed that TT-118 is a strain of R. honei which was previously isolated in Thailand. These results elucidate the presence of a unique SFG rickettsial species in Australasia.
Proceedings Article•
01 Jan 1998TL;DR: A prosodic corpus in five languages (French, English, Italian, German and Spanish) comprising 4 hours and 20 minutes of speech and involving 50 different speakers (5 male and 5 female per language) is presented.
Abstract: We present a prosodic corpus in five languages (French, English, Italian, German and Spanish) comprising 4 hours and 20 minutes of speech and involving 50 different speakers (5 male and 5 female per language). The recordings on which the corpus is based are extracted from the EUROM 1 speech database and consists of passages of about five sentences. The corpus was stylized automatically by an algorithm which factors out microprosodic effects and represents the intonation contour of utterances by a series of target points. Once interpolated by a smooth curve (spline), these points produce a contour undistinguishable from the original when re-synthesized, apart from a few detection errors. A symbolic coding of the 50000 pitch movements of the corpus is also provided, along with the time-alignment of orthographic transcription to signal at wordlevel. The entire corpus was verified and manually corrected by experts for each language. It will be made available at production cost for research through the European Language Resource Association (ELRA).
TL;DR: The structure of reduced NiR-Pa is described both in the unbound form and with the physiological product, NO, bound at the d1 heme active site, which indicates that the conformational changes involved in catalysis are considerably diverse.
Abstract: Nitrite reductase (NiR) from Pseudomonas aeruginosa (EC 1.9.3.2) (NiR-Pa) is a soluble enzyme catalyzing the reduction of nitrite (NO2-) to nitric oxide (NO). The enzyme is a 120 kDa homodimer, in which each monomer carries one c and one d1 heme. The oxidized and reduced forms of NiR from Paracoccus denitrificans GB17 (previously called Thiosphaera pantotropha) (NiR-Pd) have been described [Fulop, V., et al. (1995) Cell 81, 369−377; Williams, P. A., et al. (1997) Nature 389, 406−412], and we recently reported on the structure of oxidized NiR-Pa at 2.15 A [Nurizzo, D., et al. (1997) Structure 5, 1157−1171]. Although the domains carrying the d1 heme are almost identical in both NiR-Pa and NiR-Pd oxidized and reduced structures, the c heme domains show a different pattern of c heme coordination, depending on the species and the redox state. The sixth d1 heme ligand in oxidized NiR-Pd was found to be Tyr25, whereas in NiR-Pa, the homologuous Tyr10 does not interact directly with Fe3+, but via a hydroxide ion....
TL;DR: The increase in mRNAs coding for calcium-handling proteins and the impairment of myocardial function which occur at a lesser degree of coronary flow reduction in senescent hearts, indicate a higher vulnerability to low-flow ischemia during aging.
Abstract: Objective: Both aging and myocardial ischemia are associated with alterations of calcium-regulating proteins We investigated the effects of graded levels of low-flow ischemia on myocardial function and on SR Ca2+-ATPase (SERCA2), Na+-Ca2+ exchanger (NCx) and ryanodine receptor (RyR2), at mRNA and protein levels in both adult and senescent myocardium Methods: Isolated hearts from 4 and 24 month old (mo) rats were retrogradely perfused during 180 min at 100% (100% CF, n =11 and n =11 respectively), 30% (30% CF, n =10 and n =12) or 15% (15% CF, n =13 and n =8) of their initial coronary flow, and active tension and coronary resistance (in % of their baseline value) were recorded After 180 min of perfusion, NCx, RyR2 and SERCA2 mRNAs (in % of age-matched 100% CF group value) and protein levels were quantitated in the left ventricles by slot blot and Western blot analysis, respectively Results: In 24 mo hearts, low-flow ischemia induced a greater fall in active tension (−65±7% vs −40±4% in 4 mo 30% CF, p <001 and −82±2% vs −60±5% in 4 mo 15% CF groups, p <005 after 15 min of ischemia) and a greater increase in coronary resistance (+357±44% vs +196±39% in 4 mo 30% CF, p <005 and +807±158% vs +292±61% in 4 mo 15% CF groups, p <0001 after 15 min of ischemia) An increased accumulation of SERCA2 (+36%) and NCx (+46%) transcripts, but not RyR2, already occurred in 24 mo 30% CF group while the 3 transcripts accumulated in 24 mo 15% CF group In 4 mo rats SERCA2 (+26%), NCx (+35%) and RyR2 (+81%) mRNA levels only increased in the 15% CF group Corresponding calcium-regulating protein levels were unaltered whatever the degree of flow reduction in both 4 mo and 24 mo hearts Conclusion: Low-flow ischemia does not induce calcium-regulating protein loss in both adult and senescent hearts The increase in mRNAs coding for calcium-handling proteins and the impairment of myocardial function which occur at a lesser degree of coronary flow reduction in senescent hearts, indicate a higher vulnerability to low-flow ischemia during aging
TL;DR: The ferritin level was found to be an independent predictor of progression of HIV disease, whereas the mean daily dose of DFX was not, and support a hypothesis that was recently expressed, that iron overload could be associated with a more rapid progression with HIV-1 infection.
Abstract: To study the respective roles of mean serum ferritin level and the mean desferrioxamine (DFX) dose on progression of HIV-1 infection, data from 49 HIV-seropositive thalassemic patients were analyzed using a Cox proportional hazards model including known confounding variables. Nine years after seroconversion, 10% of those who had been prescribed >40 mg/kg of DFX daily had entered stage IV versus 39% of those who had been prescribed a lower dose. Patients with ferritin level >1935 g/L entered stage IV more rapidly than those with a lower level (31% versus 16%). In multivariate analysis, the ferritin level was found to be an independent predictor of progression of HIV disease, whereas the mean daily dose of DFX was not. Similar results were obtained when death was the endpoint. Our results support a hypothesis that was recently expressed, that iron overload could be associated with a more rapid progression of HIV-1 infection.
Comenius University in Bratislava1, CERN2, Helsinki Institute of Physics3, Karlsruhe Institute of Technology4, Jožef Stefan Institute5, Aix-Marseille University6, University of Milan7, University of Paris8, University of Oxford9, University of Padua10, Collège de France11, Centre national de la recherche scientifique12, Charles University in Prague13, Istituto Superiore di Sanità14, University of Cantabria15, Uppsala University16
01 Aug 1998-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The DELPHI Silicon Tracker as discussed by the authors is an ensemble of microstrips, ministrips and pixels, which has accumulated over 70 pb −1 of high-energy data.
Abstract: The DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over 70 pb −1 of high-energy data. The Tracker is optimised for the LEP2 physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three-dimensional b tagging information is available down to a polar angle of 25°. Impact parameter resolutions have been measured of 28 μ m ⊕ 71/(p sin 3/2 θ) μ m in Rφ and 34 μ m ⊕ 69/p μ m in Rz , where p is the track momentum in GeV/ c . The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of 330×330 μ m 2 and the ministrips have a readout pitch of 200 μ m. The forward part of the detector shows average efficiencies of more than 96%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking efficiency for the region with polar angle less than 25°.
TL;DR: This transcription map provides a detailed description of gene order for the 8p11‐p21 region and will be helpful in the identification of candidate genes for diseases and the mapping of two types of molecular alterations that occur in sporadic breast cancers, i.e., amplification and deletion.
Abstract: Several genes, most of them unknown, of the short arm of chromosome 8 are involved in malignant diseases. Numerous studies have implicated a portion of the 8p11-p21 region as the location of one or more tumor suppressor genes involved in a variety of human cancers, including breast cancer. We and others have reported linkage analyses suggesting the presence of a putative breast cancer susceptibility gene. Furthermore, several oncogenes of the 8p11-p12 region are involved in reciprocal translocations in myeloproliferative and myelodysplastic disorders and in amplification in breast cancer. To facilitate the analysis of the 8p11-p21 region and the cloning of candidate oncogenes and tumor suppressor genes, a high-resolution physical and transcriptional map was established with 39 yeast artificial chromosomes and 94 markers, including so-called sequence-tagged sites and expressed sequence-tagged sites derived from either known genes or expressed sequence tags corresponding to unidentified transcripts. In addition, four novel transcripts were identified and localized precisely within the map. This transcription map provides a detailed description of gene order for the 8p11-p21 region and will be helpful in the identification of candidate genes for diseases. From this basis, we refined the mapping of two types of molecular alterations that occur at 8p11-p21 in sporadic breast cancers, i.e., amplification and deletion.
Journal Article•
TL;DR: By comparing cells with respect to several motility-related properties and the ability to migrate on fibronectin, three cell types can be distinguished in the Xenopus gastrula, yielding cell types which are not found in the embryo.
Abstract: By comparing cells with respect to several motility-related properties and the ability to migrate on fibronectin, three cell types can be distinguished in the Xenopus gastrula. These occur in a distinct spatial pattern, thus defining three motility domains which do not correspond to the prospective germ layers. Migratory behavior is confined to a region encompassing the anterior mesoderm and endoderm. When stationary animal cap cells are induced to migrate by treatment with activin, cells become adhesive at low concentrations of fibronectin, show polarized protrusive activity, and form lamellipodia. Adhesion and polarization, but not lamellipodia formation, are mimicked by the immediate early response gene Mix.1. Goosecoid, another immediate early gene, is without effect when expressed alone in animal cap cells, but it acts synergistically with Mix.1 in the control of adhesion, and antagonistically in the polarization of protrusive activity. bFGF also induces migration, lamellipodia formation and polarization in animal cap cells, but has no effect on adhesion. By the various treatments of animal cap cells, new combinations of motile properties can be generated, yielding cell types which are not found in the embryo.
TL;DR: In this paper, a detailed analysis of the Ar XVII line shape formed in a high-energy-density implosion is described, and a one-dimensional radiation-hydrodynamics simulation of the implosion was performed.
Abstract: We describe an experimental investigation, a detailed analysis of the Ar XVII ${1s}^{2}{}^{1}S--1s3p{}^{1}P$ (He\ensuremath{\beta}) line shape formed in a high-energy-density implosion, and report on one-dimensional radiation-hydrodynamics simulation of the implosion. In this experiment trace quantities of argon are doped into a lower-$Z$ gas-filled core of a plastic microsphere. The dopant level is controlled to ensure that the He\ensuremath{\beta} transition is optically thin and easily observable. Then the observed line shape is used to derive electron temperatures ${(T}_{e})$ and electron densities ${(n}_{e}).$ The high-energy density plasma, with ${T}_{e}$ approaching 1 keV and ${n}_{e}{=10}^{24}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3},$ is created by placing the microsphere in a gold cylindrical enclosure, the interior of which is directly irradiated by a high-energy laser; the x rays produced by this laser-gold interaction indirectly implode the microsphere. Central to the interpretation of the hydrodynamics of the implosions is the characterization and understanding of the formation of these plasmas. To develop an understanding of the plasma and its temporal evolution, time-resolved ${T}_{e}$ and ${n}_{e}$ measurements are extracted using techniques that are independent of the plasma hydrodynamics. Comparing spectroscopic diagnostics with measurements derived from other diagnostic methods, we find the spectroscopic measurements to be reliable and further we find that the experiment-to-experiment comparison shows that these implosions are reproducible.
TL;DR: In this article, the authors investigated the development of iron crust lateritic systems and rain forest soils in tropical environments using in situ-produced 10Be in quartz veins and cobbles.
TL;DR: In this article, an excess of 66±14 (stat.) events were observed in the D∗+π+π−π− final state with a mass of 2637±2(stat.)±6(syst.) MeV/c2 and a full width smaller than 15 MeV /c2 (95% C.L.).
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TL;DR: The value of the b quark mass at the M Z scale defined in the MS renormalization scheme was determined using 2.8 million hadronic Z decays collected during 1992-1994 by the DELPHI detector to be m b (M Z )=2.67±0.25 ( stat. )± 0.34 ( frag. )−0.27 ( theo. ) GeV/c 2 ).
TL;DR: The biochemical variations observed in the gut seem to be linked to both the reproductive cycle and the sea urchin's trophic activity, and this echinoid represents an important store of materials and energy within this lagoonal environment.
Abstract: . Monthly soluble and insoluble protein, carbohydrate, lipid and ash levels and energetic content were measured in tissues of Paracentrotus lividus adults living in a lagoonal environment over a 1-year period to increase our understanding of resource allocation to the different tissues. The biochemical composition of P. lividus individuals in this environment is similar to that observed in other environments. The gonad and gut contained a high level of proteins soluble or insoluble, a lesser amount of lipids and, finally, a low level of carbohydrates. The main component of the test was ash, followed by protein levels. The lipid and carbohydrate levels in the test were very low. Seasonal variability in the biochemical composition of the different body parts was observed. In the gonad, an increase in the level of lipids was recorded concomitant to an increase in gonad weight. The lipids and carbohydrates, after an initial increase, decreased with the maturation of the gonad. The biochemical variations observed in the gut seem to be linked to both the reproductive cycle and the sea urchin's trophic activity. Variability in the test was low and irregular for all of the observed biochemical components. As P. lividus is an important member of the benthic community in the Urbinu lagoon, this echinoid represents an important store of materials and energy within this lagoonal environment.
TL;DR: A search for stable and long-lived heavy charged particles used the data taken by the DELPHI experiment at energies from 130 to 183 GeV as mentioned in this paper, where the Cherenkov light detected in the Ring ImagingCherenkov D...
TL;DR: In this article, two types of Pan-African-Brasiliano fold belts have been distinguished: the first type is characterized by an old long-lived tectonic cycle (1000-600 Ma) and is generally oceanic.
TL;DR: In this paper, the total and the differential cross sections for the reaction e+e− → γγ(γ) have been measured with the DELPHI detector at LEP using an integrated luminosity of 36.9 pb−1.
TL;DR: In this article, the authors measured trilinear gauge boson couplings using data taken by DELPHI at 161 GeV and 172 GeV, and derived limits on neutral ZVγ couplings from an analysis of the reaction.
TL;DR: Results show that PET and MEG MEF1 activation signals spatially coincide within instrumental, registration, and modeling errors.
TL;DR: In this article, the double-differential inclusive di-jet cross section in photoproduction processes is measured with the H1 detector at HERA and the cross section is determined as a function of the average transverse jet energy.
Abstract: The double-differential inclusive di-jet cross section in photoproduction processes is measured with the H1 detector at HERA. The cross section is determined as a function of the average transverse jet energyETjets for ranges of the fractional energyξγjets of the parton from the photon side. An effective leading order parton distribution in the photon is determined at large parton fractional energies for scale between 80