Showing papers by "Centre national de la recherche scientifique published in 1995"
TL;DR: This research presents a new probabilistic procedure called ‘spot-spot analysis’ to characterize the response of the immune system to the presence of E.coli.
6,818 citations
TL;DR: Together, these properties make PEI a promising vector for gene therapy and an outstanding core for the design of more sophisticated devices because its efficiency relies on extensive lysosome buffering that protects DNA from nuclease degradation, and consequent lysOSomal swelling and rupture that provide an escape mechanism for the PEI/DNA particles.
Abstract: Several polycations possessing substantial buffering capacity below physiological pH, such as lipopolyamines and polyamidoamine polymers, are efficient transfection agents per se--i.e., without the addition of cell targeting or membrane-disruption agents. This observation led us to test the cationic polymer polyethylenimine (PEI) for its gene-delivery potential. Indeed, every third atom of PEI is a protonable amino nitrogen atom, which makes the polymeric network an effective "proton sponge" at virtually any pH. Luciferase reporter gene transfer with this polycation into a variety of cell lines and primary cells gave results comparable to, or even better than, lipopolyamines. Cytotoxicity was low and seen only at concentrations well above those required for optimal transfection. Delivery of oligonucleotides into embryonic neurons was followed by using a fluorescent probe. Virtually all neurons showed nuclear labeling, with no toxic effects. The optimal PEI cation/anion balance for in vitro transfection is only slightly on the cationic side, which is advantageous for in vivo delivery. Indeed, intracerebral luciferase gene transfer into newborn mice gave results comparable (for a given amount of DNA) to the in vitro transfection of primary rat brain endothelial cells or chicken embryonic neurons. Together, these properties make PEI a promising vector for gene therapy and an outstanding core for the design of more sophisticated devices. Our hypothesis is that its efficiency relies on extensive lysosome buffering that protects DNA from nuclease degradation, and consequent lysosomal swelling and rupture that provide an escape mechanism for the PEI/DNA particles.
6,213 citations
TL;DR: In this paper, the results of a study to develop natural zircon geochemical standards for calibrating the U-(Th)-Pb geochronometer and Hf isotopic analyses are reported.
Abstract: We report here the results of a study to develop natural zircon geochemical standards for calibrating the U-(Th)-Pb geochronometer and Hf isotopic analyses. Additional data were also collected for the major, minor and trace element contents of the three selected sample sets. A total of five large zircon grains (masses between 0.5 and 238 g) were selected for this study, representing three different suites of zircons with ages of 1065 Ma, 2.5 Ma and 0.9 Ma. Geochemical laboratories can obtain these materials by contacting Geostandards Newsletter.
4,845 citations
TL;DR: A new dynamic model for friction is proposed that captures most of the friction behavior that has been observed experimentally, including the Stribeck effect, hysteresis, spring-like characteristics for stiction, and varying break-away force.
Abstract: In this paper we propose a new dynamic model for friction. The model captures most of the friction behavior that has been observed experimentally. This includes the Stribeck effect, hysteresis, spring-like characteristics for stiction, and varying break-away force. Properties of the model that are relevant to control design are investigated by analysis and simulation. New control strategies, including a friction observer, are explored, and stability results are presented. >
3,416 citations
3,026 citations
TL;DR: Data indicate that the newly discovered heptadecapeptide is an endogenous agonist of the ORL1 receptor and that it may be endowed with pro-nociceptive properties.
Abstract: The ORL1 receptor, an orphan receptor whose human and murine complementary DNAs have recently been characterized, structurally resembles opioid receptors and is negatively coupled with adenylate cyclase. ORL1 transcripts are particularly abundant in the central nervous system. Here we report the isolation, on the basis of its ability to inhibit the cyclase in a stable recombinant CHO(ORL1+) cell line, of a neuropeptide that resembles dynorphin A9 and whose amino acid sequence is Phe-Gly-Gly-Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln. The rat-brain cDNA encodes the peptide flanked by Lys-Arg proteolytic cleavage motifs. The synthetic heptadecapeptide potently inhibits adenylate cyclase in CHO(ORL1+) cells in culture and induces hyperalgesia when administered intracerebroventricularly to mice. Taken together, these data indicate that the newly discovered heptadecapeptide is an endogenous agonist of the ORL1 receptor and that it may be endowed with pro-nociceptive properties.
1,874 citations
TL;DR: The wealth of information provided by the recent structure determinations of many different glycosyl hydrolases shows that the substrate specificity and the mode of action of these enzymes are governed by exquisite details of their three-dimensional structures rather than by their global fold.
1,873 citations
TL;DR: The results show that the notion of ``double exchange'' must be generalized to include changes in the Mn-Mn electronic hopping parameter as a result of changes inThe Mn-O-Mm bond angle.
Abstract: A detailed study of doped LaMn${\mathrm{O}}_{3}$ with fixed carrier concentration reveals a direct relationship between the Curie temperature ${T}_{c}$ and the average ionic radius of the La site $〈{r}_{A}〉$, which is varied by substituting different rare earth ions for La. With decreasing $〈{r}_{A}〉$, magnetic order and significant magnetoresistance occur at lower temperatures with increasing thermal hysteresis, and the magnitude of the magnetoresistance increases dramatically. These results show that the notion of ``double exchange'' must be generalized to include changes in the Mn-Mn electronic hopping parameter as a result of changes in the Mn-O-Mn bond angle.
1,654 citations
TL;DR: Assessment of mitochondrial ROS generation provides an accurate picture of PCD-mediated lymphocyte depletion and indicates alterations of mitochondrial function constitute an important feature of early PCD.
Abstract: Programmed cell death (PCD) is a physiological process commonly defined by alterations in nuclear morphology (apoptosis) and/or characteristic stepwise degradation of chromosomal DNA occurring before cytolysis. However, determined characteristics of PCD such as loss in mitochondrial reductase activity or cytolysis can be induced in enucleated cells, indicating cytoplasmic PCD control. Here we report a sequential disregulation of mitochondrial function that precedes cell shrinkage and nuclear fragmentation. A first cyclosporin A-inhibitable step of ongoing PCD is characterized by a reduction of mitochondrial transmembrane potential, as determined by specific fluorochromes (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine++ + iodide; 3,3'dihexyloxacarbocyanine iodide). Cytofluorometrically purified cells with reduced mitochondrial transmembrane potential are initially incapable of oxidizing hydroethidine (HE) into ethidium. Upon short-term in vitro culture, such cells acquire the capacity of HE oxidation, thus revealing a second step of PCD marked by mitochondrial generation of reactive oxygen species (ROS). This step can be selectively inhibited by rotenone and ruthenium red yet is not affected by cyclosporin A. Finally, cells reduce their volume, a step that is delayed by radical scavengers, indicating the implication of ROS in the apoptotic process. This sequence of alterations accompanying early PCD is found in very different models of apoptosis induction: glucocorticoid-induced death of lymphocytes, activation-induced PCD of T cell hybridomas, and tumor necrosis factor-induced death of U937 cells. Transfection with the antiapoptotic protooncogene Bcl-2 simultaneously inhibits mitochondrial alterations and apoptotic cell death triggered by steroids or ceramide. In vivo injection of fluorochromes such as 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide; 3,3'dihexyloxacarbocyanine iodide; or HE allows for the detection of cells that are programmed for death but still lack nuclear DNA fragmentation. In particular, assessment of mitochondrial ROS generation provides an accurate picture of PCD-mediated lymphocyte depletion. In conclusion, alterations of mitochondrial function constitute an important feature of early PCD.
1,561 citations
TL;DR: Improvements brought about by predicting all the sequences of a set of aligned proteins belonging to the same family are reported by improving the success rate in the prediction of the secondary structure of proteins.
Abstract: Recently a new method called the self-optimized prediction method (SOPM) has been described to improve the success rate in the prediction of the secondary structure of proteins. In this paper we report improvements brought about by predicting all the sequences of a set of aligned proteins belonging to the same family. This improved SOPM method (SOPMA) correctly predicts 69.5% of amino acids for a three-state description of the secondary structure (alpha-helix, beta-sheet and coil) in a whole database containing 126 chains of non-homologous (less than 25% identity) proteins. Joint prediction with SOPMA and a neural networks method (PHD) correctly predicts 82.2% of residues for 74% of co-predicted amino acids. Predictions are available by Email to deleage@ibcp.fr or on a Web page (http:@www.ibcp.fr/predict.html).
1,468 citations
TL;DR: The X-ray structure of the heterodimeric Ni–Fe hydrogenase from Desulfovibrio gigas, the enzyme responsible for the metabolism of molecular hydrogen, has been solved at 2.85 Å resolution and suggests plausible electron and proton transfer pathways.
Abstract: The X-ray structure of the heterodimeric Ni–Fe hydrogenase from Desulfovibrio gigas, the enzyme responsible for the metabolism of molecular hydrogen, has been solved at 2.85 A resolution. The active site, which appears to contain, besides nickel, a second metal ion, is buried in the 60K subunit. The 28K subunit, which coordinates one [3Fe–4S] and two [4Fe–4S] clusters, contains an amino-terminal domain with similarities to the redox protein flavodoxin. The structure suggests plausible electron and proton transfer pathways.
TL;DR: The concept of critical flux is introduced in this article to identify the critical flux and the desirability of starting filtration operations at a low flux, where a flux below which a decline of flux with time does not occur.
TL;DR: A PCR assay that allows simultaneous detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci was developed and offered a specific and rapid alternative to antibiotic susceptibility tests, in particular for detection of low-level vancomycin resistance.
Abstract: A PCR assay that allows simultaneous detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci (Enterococcus faecium, E. faecalis, E. gallinarum, and E. casseliflavus) was developed. This assay was based on specific amplification of internal fragments of genes encoding D-alanine:D-alanine ligases and related glycopeptide resistance proteins. The specificity of the assay was tested on 5 well-characterized glycopeptide-resistant strains and on 15 susceptible enterococcal type strains. Clinical isolates of enterococci that could not be identified to the species level by conventional methods were identified by the PCR test. This assay offers a specific and rapid alternative to antibiotic susceptibility tests, in particular for detection of low-level vancomycin resistance.
TL;DR: A linear zipper of molecules that mirrors the linear structure of the intracellular filaments with which cadherins associate may provide a mechanism to marshal individual molecular adhesive interactions into strong bonds between cells.
Abstract: Crystal structures of the amino-terminal domain of N-cadherin provide a picture at the atomic level of a specific adhesive contact between cells. A repeated set of dimer interfaces is common to the structure in three lattices. These interactions combine to form a linear zipper of molecules that mirrors the linear structure of the intracellular filaments with which cadherins associate. This cell-adhesion zipper may provide a mechanism to marshal individual molecular adhesive interactions into strong bonds between cells.
TL;DR: A sequence of PCD-associated events in which a reduction in delta psi m constitutes an obligate irreversible step of ongoing lymphocyte death, preceding other alterations of cellular physiology, and thus allowing for the ex vivo assessment ofPCD is suggested.
Abstract: In a number of experimental systems in which lymphocyte depletion was induced by apoptosis-inducing manipulations, no apoptotic morphology and ladder-type DNA fragmentation were detected among freshly isolated peripheral lymphocytes ex vivo. Here we report that one alteration that can be detected among splenocytes stimulated with lymphocyte-depleting doses of dexamethasone (DEX) in vivo is a reduced uptake of 3,3'dihexyloxacarbocyanine iodide (DiOC6[3]), a fluorochrome which incorporates into cells dependent upon their mitochondrial transmembrane potential (delta psi m). In contrast, ex vivo isolated splenocytes still lacked established signs of programmed cell death (PCD):DNA degradation into high or low molecular weight fragments, ultrastructural changes of chromatin arrangement and endoplasmatic reticulum, loss in viability, or accumulation of intracellular peroxides. Moreover, no changes in cell membrane potential could be detected. A reduced delta psi m has been observed in response to different agents inducing lymphoid cell depletion in vivo (superantigen and glucocorticoids [GC]), in mature T and B lymphocytes, as well as their precursors. DEX treatment in vivo, followed by cytofluorometric purification of viable delta psi mlow splenic T cells ex vivo, revealed that this fraction of cells is irreversibly committed to undergoing DNA fragmentation. Immediately after purification neither delta psi mlow, nor delta psi mhigh cells, exhibit detectable DNA fragmentation. However, after short-term culture (37 degrees C, 1 h) delta psi mlow cells show endonucleolysis, followed by cytolysis several hours later. Incubation of delta psi mlow cells in the presence of excess amount of the GC receptor antagonist RU38486 (which displaces DEX from the GC receptor), cytokines that inhibit DEX-induced cell death, or cycloheximide fails to prevent cytolysis. The antioxidant, N-acetylcysteine, as well as linomide, an agent that effectively inhibits DEX or superantigen-induced lymphocyte depletion in vivo, also stabilize the DiOC6(3) uptake. In contrast, the endonuclease inhibitor, aurintricarboxylic acid acts at later stages of apoptosis and only retards the transition from the viable delta psi mlow to the nonviable fraction. Altogether, these data suggest a sequence of PCD-associated events in which a reduction in delta psi m constitutes an obligate irreversible step of ongoing lymphocyte death, preceding other alterations of cellular physiology, and thus allowing for the ex vivo assessment of PCD.
TL;DR: Pup behavioral alterations, including trembling, difficulty in righting, and fearfulness were reversed by the serotonin synthesis inhibitor parachlorophenylalanine, and adults manifested a distinct behavioral syndrome, including enhanced aggression in males.
Abstract: Deficiency in monoamine oxidase A (MAOA), an enzyme that degrades serotonin and norepinephrine, has recently been shown to be associated with aggressive behavior in men of a Dutch family. A line of transgenic mice was isolated in which transgene integration caused a deletion in the gene encoding MAOA, providing an animal model of MAOA deficiency. In pup brains, serotonin concentrations were increased up to ninefold, and serotonin-like immunoreactivity was present in catecholaminergic neurons. In pup and adult brains, norepinephrine concentrations were increased up to twofold, and cytoarchitectural changes were observed in the somatosensory cortex. Pup behavioral alterations, including trembling, difficulty in righting, and fearfulness were reversed by the serotonin synthesis inhibitor parachlorophenylalanine. Adults manifested a distinct behavioral syndrome, including enhanced aggression in males.
TL;DR: It is shown that ob gene exhibits diurnal variation, increasing during the night, after rats start eating, which is linked to changes in food intake, as fasting prevented the cyclic variation and decreased ob messenger RNA.
Abstract: Obesity is a disorder of energy balance, indicating a chronic disequilibrium between energy intake and expenditure. Recently, the mouse ob gene, and subsequently its human and rat homologues, have been cloned. The ob gene product, leptin, is expressed exclusively in adipose tissue, and appears to be a signalling factor regulating body-weight homeostasis and energy balance. Because the level of ob gene expression might indicate the size of the adipose depot, we suggest that it is regulated by factors modulating adipose tissue size. Here we show that ob gene exhibits diurnal variation, increasing during the night, after rats start eating. This variation was linked to changes in food intake, as fasting prevented the cyclic variation and decreased ob messenger RNA. Furthermore, refeeding fasted rats restored ob mRNA within 4 hours to levels of fed animals. A single insulin injection in fasted animals increased ob mRNA to levels of fed controls. Experiments to control glucose and insulin independently in animals, and studies in primary adipocytes, showed that insulin regulates ob gene expression directly in rats, regardless of its glucose-lowering effects. Whereas the ob gene product, leptin, has been shown to reduce food intake and increase energy expenditure, our data demonstrate that ob gene expression is increased after food ingestion in rats, perhaps through a direct action of insulin on the adipocyte.
TL;DR: In this article, a complete list of "mass excesses" is presented, which is an update of the similar values in the 1993 Atomic Mass Evaluation, and a list of the isomeric transition energies which are best determined from a combination of masses.
TL;DR: Interest in the role of litter decomposition in the global carbon cycle has increased recently since (1) increased atmospheric carbon dioxide will probably affect the chemical quality of litter (especially nitrogen content), and (2) global warming may enhance decomposition rates.
Abstract: Litter decomposition is controlled by three main factors: climate, litter quality and the nature and abundance of the decomposing organisms. Climate is the dominant factor in areas subjected to unfavourable weather conditions, whereas litter quality largely prevails as the regulator under favourable conditions. Litter quality remains important until the late decomposition stages through its effects on humus formation. Interest in the role of litter decomposition in the global carbon cycle has increased recently since (1) increased atmospheric carbon dioxide will probably affect the chemical quality of litter (especially nitrogen content), and (2) global warming may enhance decomposition rates.
TL;DR: It appears that molecules that participate in apoptotic decisionmaking also exert functions that are vital for normal cell proliferation and intermediate metabolism.
Abstract: Programmed cell death (PCD) is involved in the removal of superfluous and damaged cells in most organ systems. The induction phase of PCD or apoptosis is characterized by an extreme heterogeneity of potential PCD-triggering signal transduction pathways. During the subsequent effector phase, the numerous PCD-inducing stimuli converge into a few stereotypical pathways and cells pass a point of no return, thus becoming irreversibly committed to death. It is only during the successive degradation phase that vital structures and functions are destroyed, giving rise to the full-blown phenotype of PCD. Evidence is accumulating that cytoplasmic structures, including mitochondria, participate in the critical effector stage and that alterations commonly considered to define PCD (apoptotic morphology of the nucleus and regular, oligonucleosomal chromatin fragmentation) have to be ascribed to the late degradation phase. The decision as to whether a cell will undergo PCD or not may be expected to be regulated by "switches" that, once activated, trigger self-amplificatory metabolic pathways. One of these switches may reside in a perturbation of mitochondrial function. Thus, a decrease in mitochondrial transmembrane potential, followed by mitochondrial uncoupling and generation of reactive oxygen species, precedes nuclear alterations. It appears that molecules that participate in apoptotic decision-making also exert functions that are vital for normal cell proliferation and intermediate metabolism.
TL;DR: In this paper, Wang et al. showed that the Ailao and Diancang Shan metamorphic cores are composed of strongly foliated and lineated mylonitic gneisses.
TL;DR: It is reported that microinjection of antibodies against human Eg5 (HsEg5) blocks centrosome migration and causes HeLa cells to arrest in mitosis with monoastral microtubule arrays and that p34cdc2 protein kinase directly regulates its localization.
TL;DR: In this article, dual-quadrature spectral interferometry and Fourier transform (FT) were used to obtain a complete measurement of the complex electric field, E(ω), as a continuous function of frequency.
Abstract: Although nonlinear methods can provide only the amplitude and the phase of an isolated ultrashort pulse, linear techniques can yield such measurements with a much better sensitivity and reliability when a reference pulse is available. We demonstrate two such methods, dual-quadrature spectral interferometry and Fourier-transform spectral interferometry. These techniques are simple to implement, very sensitive, and provide a complete measurement of the complex electric field, E(ω), as a continuous function of frequency.
01 May 1995
TL;DR: In this paper, the problem of classifying an unseen pattern on the basis of its nearest neighbors in a recorded data set is addressed from the point of view of Dempster-Shafer theory to provide a global treatment of such issues as ambiguity and distance rejection, and imperfect knowledge regarding the class membership of training patterns.
Abstract: In this paper, the problem of classifying an unseen pattern on the basis of its nearest neighbors in a recorded data set is addressed from the point of view of Dempster-Shafer theory. Each neighbor of a sample to be classified is considered as an item of evidence that supports certain hypotheses regarding the class membership of that pattern. The degree of support is defined as a function of the distance between the two vectors. The evidence of the k nearest neighbors is then pooled by means of Dempster's rule of combination. This approach provides a global treatment of such issues as ambiguity and distance rejection, and imperfect knowledge regarding the class membership of training patterns. The effectiveness of this classification scheme as compared to the voting and distance-weighted k-NN procedures is demonstrated using several sets of simulated and real-world data. >
TL;DR: Ageing of large size plates and millimetric beads showed that devices with dimensions smaller than the thickness of the outer layer should degrade less rapidly than larger ones, and heterogeneously and faster than homogeneously degraded submillimetric films and particles.
TL;DR: St sterically stabilized nanospheres were developed using amphiphilic diblock or multiblock copolymers and exhibited increased blood circulation times and reduced liver accumulation, depending on the coating polyethylene glycol molecular weight and surface density.
TL;DR: A physical map has been constructed of the human genome containing 15,086 sequence-tagged sites (STSs), with an average spacing of 199 kilobases, anchored by the radiation hybrid and genetic maps.
Abstract: A physical map has been constructed of the human genome containing 15,086 sequence-tagged sites (STSs), with an average spacing of 199 kilobases. The project involved assembly of a radiation hybrid map of the human genome containing 6193 loci and incorporated a genetic linkage map of the human genome containing 5264 loci. This information was combined with the results of STS-content screening of 10,850 loci against a yeast artificial chromosome library to produce an integrated map, anchored by the radiation hybrid and genetic maps. The map provides radiation hybrid coverage of 99 percent and physical coverage of 94 percent of the human genome. The map also represents an early step in an international project to generate a transcript map of the human genome, with more than 3235 expressed sequences localized. The STSs in the map provide a scaffold for initiating large-scale sequencing of the human genome.
TL;DR: The WAVES investigation on the WIND spacecraft will provide comprehensive measurements of the radio and plasma wave phenomena which occur in Geospace as mentioned in this paper, in coordination with the other onboard plasma, energetic particles, and field measurements will help us understand the kinetic processes that are important in the solar wind and in key boundary regions of the Geospace.
Abstract: The WAVES investigation on the WIND spacecraft will provide comprehensive measurements of the radio and plasma wave phenomena which occur in Geospace. Analyses of these measurements, in coordination with the other onboard plasma, energetic particles, and field measurements will help us understand the kinetic processes that are important in the solar wind and in key boundary regions of the Geospace. These processes are then to be interpreted in conjunction with results from the other ISTP spacecraft in order to discern the measurements and parameters for mass, momentum, and energy flow throughout geospace. This investigation will also contribute to observations of radio waves emitted in regions where the solar wind is accelerated. The WAVES investigation comprises several innovations in this kind of instrumentation: among which the first use, to our knowledge, of neural networks in real-time on board a scientific spacecraft to analyze data and command observation modes, and the first use of a wavelet transform-like analysis in real time to perform a spectral analysis of a broad band signal.
TL;DR: In this article, a detailed XPS study of several oxides of vanadium is reported in an attempt to characterize clearly the surface of these oxides, and several parameters, such as the FWHM of the v2p 3 2 and O1s XPS peaks, their shape and binding energy difference, have been utilized.
TL;DR: In this article, the presence of high concentrations of acetone and methanol in the free troposphere has been reported, indicating that acetone photochemistry provides a quantitatively significant pathway for sequestering NOx in the form of peroxyacetylnitrate, a relatively unreactive temporary reservoir of NOx.
Abstract: OXYGENATED species in the atmosphere are important sources of free radicals and are intricately linked with the fate of nitrogen oxides (NOx), which are themselves necessary for tropospheric ozone formation1,2. With the exception of formaldehyde, oxygenated hydrocarbons have rarely been measured in the free troposphere. Here we report airborne measurements indicating the presence of high concentrations (compared to those of routinely measured C2–C6 tropospheric hydrocarbons3,4) of acetone and methanol. We use a three-dimensional model to show that acetone photochemistry provides a quantitatively significant (up to 50%) pathway for sequestering NOx in the form of peroxyacetylnitrate, a relatively unreactive temporary reservoir of NOx. Furthermore, in the dry regions of the upper troposphere, acetone can provide a large primary source of HOx (OH + HO2) radicals, resulting in increased ozone production. This surprisingly significant contribution of such oxygenated hydrocarbons to tropospheric NOx, HOx and ozone cycling is likely to be affected by their changing natural and anthropogenic emissions due to land-use change, biomass burning and alcohol-based biofuel use.