Showing papers by "Université Paris-Saclay published in 1990"
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TL;DR: Results from this study indicate that there are also similarities between the normal tissue distribution GST-pi and that previously reported for mammalian P-glycoprotein, particularly in secretory epithelia, suggesting that these two gene products, which have been implicated in the development of resistance to cytotoxic drugs, may be coregulated in normal and malignant cells.
Abstract: Glutathione S-transferases (GSTs), a family of isoenzymes that play an important role in protecting cells from cytotoxic and carcinogenic agents, can be separated by biochemical and immunologic characteristics into three distinct classes named alpha, mu, and pi. Previous studies have indicated that there is marked heterogeneity in the expression of different GST isoenzymes in different normal and malignant tissues. To better understand the regulation of the human pi class glutathione S-transferase isoenzyme (GST-pi), the tissue distribution of this protein wa studied by an immunohistochemical technique using an anti-GST-pi polyclonal antibody in normal paraffin-embedded human tissues. These studies indicate that there is a broad distribution of GST-pi in normal human tissues and establish a precise localization within the different organs studied. GST-pi was expressed predominantly in normal epithelial cells of the urinary, digestive, and respiratory tracts, suggesting a possible role for GST-pi in detoxication and elimination of toxic substances. Previous studies have indicated that GST-pi and the putative drug efflux pump P-glycoprotein are both overexpressed in multidrug-resistant human breast cancer cells and in xenobiotic resistant preneoplastic rat hyperplastic liver nodules. Results from this study indicate that there are also similarities between the normal tissue distribution GST-pi and that previously reported for mammalian P-glycoprotein, particularly in secretory epithelia. This finding suggests that these two gene products, which have been implicated in the development of resistance to cytotoxic drugs, may be coregulated in normal and malignant cells.
167 citations
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TL;DR: Theoretical calculations and models to explain two unusual features of Fe/Cr magnetically layered structures are presented in this paper, where strong antiferromagnetic (AF) couplings between Fe layers separated by Cr layers have been found.
Abstract: Theoretical calculations and models to explain two unusual features of Fe/Cr magnetically layered structures are presented: (1) Strong antiferromagnetic (AF) couplings between Fe layers separated by Cr layers have been found in Fe/Cr/Fe sandwiches and Fe/Cr superlattices. These AF couplings are too strong to be accounted for by dipolar interactions and have to be ascribed to exchange interactions through the Cr layers. The interlayer exchange coupling from numerical calculations of the electronic structure of Fe/Cr superlattices based on the local density approximation is derived. (2) Recently, giant magnetoresistance effects have been found in Fe/Cr magnetically layered structures for currents in the plane of the layers. The spin‐dependent scattering at the Fe/Cr interfaces that comes from interface roughness, as well as that in the bulk of the layers are considered. The resistivity of these magnetic superlattices are calculated by adapting the quantum treatment of the electrical conductivity of ultrathi...
126 citations
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TL;DR: In this paper, the authors search for Z 0 decays into acoplanar pairs of leptons or jets and obtain model independent limits on branching ratios for the Z 0 to decay into pairs of heavy particles with subsequent decays.
44 citations
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42 citations
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TL;DR: In this article, the authors derived the strong coupling constant α s (M 2 Z 0 ) from the energy-energy correlation distribution and its asymmetry, respectively, assuming the QCD renormalization scale μ = M Z 0.
41 citations
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TL;DR: It is concluded that MX2 conquers multidrug resistance by rapid influx following a higher frequency of formation of DNA single- and double-strand breaks in K562/ADM cells.
Abstract: The mechanism of action of 3′-deamino-3′-morpholino-13-deoxo-10-hydroxycarminomycin (MX2) was examined in a human leukemia cell line (K562) and its Adriamycin (ADM)-resistant subline (K562/ADM). ADM and MX2 showed an equivalent antitumor effect against K562. K562/ADM was highly resistant to ADM. In cellular pharmacokinetic studies, MX2 showed faster and greater influx than did ADM in both K562 and K562/ADM. The efflux of ADM was rapid in K562/ADM but not in K562. On the other hand, the efflux of MX2 was rapid in both cell lines. The formation of DNA single-strand breaks and double-strand breaks by ADM was significantly lower in K562/ADM than K562. On the other hand, formation of those breaks by MX2 was not decreased. Although some of the DNA breaks induced by MX2 were resealed, there was no difference in the degree of resealing in K562 and K562/ADM cells. On the other hand, most of the small number of DNA breaks in K562/ADM induced by ADM were resealed. The topoisomerase II activity in K562 and K562/ADM was not significantly different. It is concluded that MX2 conquers multidrug resistance by rapid influx following a higher frequency of formation of DNA single- and double-strand breaks in K562/ADM cells.
36 citations
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TL;DR: In this article, the authors make an inquiry with professionals of the forming in physical and sports education, moving closer to this weak development of the popular sports with the cultural inheritance of the country.
31 citations
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TL;DR: A novel triterpenoid, lantadene D, has been isolated from the leaves of the hepatotoxic plant Lantana camara var.
29 citations
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TL;DR: In this paper, upper and lower limits on excited neutrino couplings were derived from the total width of the Z width, independent of the v∗ decay modes, for the ALEPH detector at LEP.
23 citations
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TL;DR: In this article, the structural size effect is regarded as the key macroscopic consequence of fracture, and the most important yardstick for the evaluation of various theories, while the knowledge of the effect of the loading rate due to viscoplastic behavior, and especially the general effect of load and deformation history is limited.
Abstract: The workshop of the above title took place in Paris, France where 36 invitees made presentations followed by extensive discussions. The themes covered at the workshop are discussed and are as as follows: observation and measurement of damage and localization; micromechanics of fracture and micro-macro relaionships; stability, bifurcation, and localization; nonlocal models, and localization limiters and size effect. Although it would not be possible formulate to conclusions acceptable to all, certain views appeared to reflect a broad consensus. In static, time-independent modeling of the tensile fracture of concrete and geomaterials, the structural size effect is widely regarded as the key macroscopic consequence of fracture, and the most important yardstick for the evaluation of various theories. It is noted that the knowledge of the effect of the loading rate due to viscoplastic behavior, and especially the general effect of load and deformation history is rather limited. These and other observations are discussed.
21 citations
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TL;DR: In this paper, the stability of trajectories in infinite-dimensional systems with strongly hyperbolic properties has been studied and a special "drift" type of perturbation in which a system with number n interacts only with systems with previous numbers has been considered.
Abstract: The authors study the stability of trajectories in infinite-dimensional systems which are perturbations of infinite chains of independent finite-dimensional systems with strongly hyperbolic properties. They consider a special 'drift' type of perturbation in which a system with number n interacts only with systems with previous numbers. They reduce the problem of stability to a problem of small perturbations in a special space with an appropriate metric and construct the corresponding version of perturbation theory. Their main result is to show that the type of hyperbolicity can be radically changed when the parameters of the system grow.
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TL;DR: Data collected by the E731 experiment at Fermilab were used to search for CPT violation in K0→ππ decays by measuring the difference Δφ between the phases of the CP-violating parameters, and the result is consistent with CPT symmetry.
Abstract: Data collected by the E731 experiment at Fermilab were used to search for {ital CPT} violation in {ital K}{sup 0}{r arrow}{pi}{pi} decays by measuring the difference {Delta}{phi} between the phases of the {ital CP}-violating parameters {eta}{sub 00} and {eta}{sub +{minus}}. Our result, {Delta}{phi}={minus}0.3{degree}{plus minus}2.4{degree}{plus minus}1.2{degree}, where the first error is statistical and the second systematic, is consistent with {ital CPT} symmetry.
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TL;DR: The structure of toxin alpha after adding the NO2 chromophore to Tyr-25 is the same as it is in native toxin, and the binding assays of [nitrotyrosyl]toxin show that after nitration the affinity toward the monoclonal antibody M alpha 1 is unchanged and that the affinity towards the cholinergic receptor from Torpedo marmorata remains high.
Abstract: Raman spectroscopy was used to determine structural features of the native toxin alpha from Naja nigricollis, which contains only one Trp and one Tyr, and of chemically modified toxins having chromophores added to these two conserved aromatic amino acids. The percentages of secondary structure were determined by using amide I polypeptidic vibration analysis and are in agreement with X-ray structure [Low et al. (1976) Proc. Natl. Acad Sci. U.S.A. 73, 2991-2994] as well as with the geometry of the disulfide bridges estimated by using the v(S-S) vibrations. In the native toxin alpha, the single invariant tyrosine 25 appears to be buried in the structure and involved in a strong hydrogen bond. We have chemically modified these two invariant aromatic side chains by addition of chromophores. The presence of a (nitrophenyl)sulfenyl (NPS) chromophore bound to the Trp does not perturb the secondary structure of the toxin as shown by the analysis of the polypeptidic amide I vibrations; however, the environment of this Trp and the geometry of a disulfide bridge seem to be modified. The secondary structure is not affected by the presence of the NPS chromophore; therefore, the decrease in binding affinity observed after modification of Trp-29 by the reagent NPS-Cl [Faure et al. (1983) Biochemistry 22, 2068-2076] is due to an alteration of the environment of this aromatic amino acid and/or a steric hindrance and not to an overall modification of the toxin structure. The binding assays of [nitrotyrosyl]toxin show that after nitration the affinity toward the monoclonal antibody M alpha 1 is unchanged and that the affinity toward the cholinergic receptor (AcChR) from Torpedo marmorata remains high. We concluded that the structure of toxin alpha after adding the NO2 chromophore to Tyr-25 is the same as it is in native toxin.
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California Institute of Technology1, Boston University2, University of California, Berkeley3, University of California, Santa Cruz4, University of Michigan5, Cornell University6, Autonomous University of Barcelona7, University of Chicago8, Harvard University9, Stanford University10, Johns Hopkins University11, Indiana University12, University of Hawaii at Manoa13, University of Oklahoma14, Polytechnic University of Catalonia15, University of Colorado Boulder16, University of Pennsylvania17, Union Bank of Switzerland18, Brookhaven National Laboratory19, Fermilab20, Université Paris-Saclay21, Columbia University22, Carleton University23, University of Wisconsin-Madison24, University of Geneva25
TL;DR: In this paper, the authors obtained upper limits for the various branching ratios ranging from 2.5{times}10{sup {minus}3} to 9.2{times]10{Sup {minus]3], at a 90% confidence level.
Abstract: Data taken by the Mark II detector at the SLAC {ital e}{sup +}{ital e}{sup {minus}} storage ring PEP was used to search for exclusive decays of {ital D}{sup {plus minus}} and {ital B}{sup {plus minus}} mesons into two charged leptons plus a charged pion or kaon. All possible charge and lepton combinations consistent with charge conservation were considered and no evidence for any signals was found. We obtain upper limits for the various branching ratios ranging from 2.5{times}10{sup {minus}3} to 9.2{times}10{sup {minus}3}, at a 90% confidence level. Some of these limits can be used to constrain leptoquark masses in various models.
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TL;DR: In this paper, a search for π 0 γ final states, in which the two photons from the Z 0 decay are unresolved, the production of pairs of high-energy electromagnetic clusters is studied.