Showing papers by "University of Bordeaux published in 2002"

Lazy abstraction

Abstract: One approach to model checking software is based on the abstract-check-refine paradigm: build an abstract model, then check the desired property, and if the check fails, refine the model and start over. We introduce the concept of lazy abstraction to integrate and optimize the three phases of the abstract-check-refine loop. Lazy abstraction continuously builds and refines a single abstract model on demand, driven by the model checker, so that different parts of the model may exhibit different degrees of precision, namely just enough to verify the desired property. We present an algorithm for model checking safety properties using lazy abstraction and describe an implementation of the algorithm applied to C programs. We also provide sufficient conditions for the termination of the method.

Photothermal imaging of nanometer-sized metal particles among scatterers.

Abstract: Ambient optical detection of labeled molecules is limited for fluorescent dyes by photobleaching and for semiconducting nanoparticles by “blinking” effects. Because nanometer-sized metal particles do not optically bleach, they may be useful optical labels if suitable detection signals can be found. We demonstrate far-field optical detection of gold colloids down to diameters of 2.5 nanometers with a photothermal method that combines high-frequency modulation and polarization interference contrast. The photothermal image is immune to the effects of scattering background, which limits particle imaging through Rayleigh scattering to diameters larger than 40 nanometers.

A Method for Visual Determination of Sex, Using the Human Hip Bone

Abstract: A new visual method for the determination of sex using the human hip bone (os coxae) is proposed, based on a revision of several previous approaches which scored isolated characters of this bone. The efficacy of the methodology is tested on a sample of 402 adults of known sex and age of French and Portuguese origins. With the simultaneous use of five characters of the hip bone, it is possible to provide a correct sexual diagnosis in 95% of all cases, with an error of 2% and an inability to identify sex in only 3%. The advantage of this new method is a reduction in observer subjectivity, since the evaluation procedure cannot involve any anticipation of the result. In addition, this method of sex determination increases the probability of a correct diagnosis with isolated fragments of the hip bone, provided that a combination of elements of one character is found to be typically male or female.

A Third Vesicular Glutamate Transporter Expressed by Cholinergic and Serotoninergic Neurons

Abstract: Two proteins previously known as Na(+)-dependent phosphate transporters have been identified recently as vesicular glutamate transporters (VGLUT1 and VGLUT2) Together, VGLUT1 and VGLUT2 are operating at most central glutamatergic synapses In this study, we characterized a third vesicular glutamate transporter (VGLUT3), highly homologous to VGLUT1 and VGLUT2 Vesicles isolated from endocrine cells expressing recombinant VGLUT3 accumulated l-glutamate with bioenergetic and pharmacological characteristics similar, but not identical, to those displayed by the type-1 and type-2 isoforms Interestingly, the distribution of VGLUT3 mRNA was restricted to a small number of neurons scattered in the striatum, hippocampus, cerebral cortex, and raphe nuclei, in contrast to VGLUT1 and VGLUT2 transcripts, which are massively expressed in cortical and deep structures of the brain, respectively At the ultrastructural level, VGLUT3 immunoreactivity was concentrated over synaptic vesicle clusters present in nerve endings forming asymmetrical as well as symmetrical synapses Finally, VGLUT3-positive neurons of the striatum and raphe nuclei were shown to coexpress acetylcholine and serotonin transporters, respectively Our study reveals a novel class of glutamatergic nerve terminals and suggests that cholinergic striatal interneurons and serotoninergic neurons from the brainstem may store and release glutamate

Response to imatinib mesylate in patients with chronic myeloproliferative diseases with rearrangements of the platelet-derived growth factor receptor beta.

Abstract: Background A small proportion of patients with chronic myeloproliferative diseases have constitutive activation of the gene for platelet-derived growth factor receptor beta (PDGFRB), which encodes a receptor tyrosine kinase. The gene is located on chromosome 5q33, and the activation is usually caused by a t(5;12)(q33;p13) translocation associated with an ETV6-PDGFRB fusion gene. The tyrosine kinase inhibitor imatinib mesylate specifically inhibits ABL, PDGFR, and KIT kinases and has impressive clinical efficacy in BCR-ABL–positive chronic myeloid leukemia. Methods We treated four patients who had chronic myeloproliferative diseases and chromosomal translocations involving 5q33 with imatinib mesylate (400 mg daily). Three of the four patients presented with leukocytosis and eosinophilia; their leukemia cells carried the ETV6-PDGFRB fusion gene. The fourth patient had leukocytosis, eosinophilia, and a t(5;12) translocation involving PDGFRB and an unknown partner gene; he also had extensive raised, ulcerated...

Mapping and Ablation of Idiopathic Ventricular Fibrillation

Abstract: Background— Ventricular fibrillation is the main mechanism of sudden cardiac death. The feasibility of eliminating recurrent episodes by catheter ablation has not been reported. Methods and Results— Twenty-seven patients without known heart disease (13 men, 14 women, 41±14 years of age) were studied after being resuscitated from recurrent (10±12) episodes of primary idiopathic ventricular fibrillation; 23 had received a defibrillator. The first initiating beat of ventricular fibrillation had an identical electrocardiographic morphology and coupling interval (297±41 ms) to preceding isolated premature beats typically noted in the aftermath of resuscitation. These triggers were localized by mapping the earliest electrical activity and ablated by local radiofrequency delivery. Outcome was assessed by Holter and defibrillator memory interrogation. Premature beats were elicited from the Purkinje conducting system in 23 patients: from the left ventricular septum in 10, from the anterior right ventricle in 9, an...

Operators, Functions, and Systems: An Easy Reading

Abstract: Together with the companion volume by the same author, Operators, Functions, and Systems: An Easy Reading. Volume 2: Model Operators and Systems, Mathematical Surveys and Monographs, Vol. 93, AMS, 2002, this unique work combines four major topics of modern analysis and its applications: A. Hardy classes of holomorphic functions, B. Spectral theory of Hankel and Toeplitz operators, C. Function models for linear operators and free interpolations, and D. Infinite-dimensional system theory and signal processing. This volume contains Parts A and B. Hardy classes of holomorphic functions is known to be the most powerful tool in complex analysis for a variety of applications, starting with Fourier series, through the Riemann $\zeta$-function, all the way to Wiener's theory of signal processing. Spectral theory of Hankel and Toeplitz operators becomes the supporting pillar for a large part of harmonic and complex analysis and for many of their applications. In this book, moment problems, Nevanlinna-Pick and Carathodory interpolation, and the best rational approximations are considered to illustrate the power of Hankel and Toeplitz operators. The book is geared toward a wide audience of readers, from graduate students to professional mathematicians, interested in operator theory and functions of a complex variable. The two volumes develop an elementary approach while retaining an expert level that can be applied in advanced analysis and selected applications. Readership Graduate students and research mathematicians interested in analysis.

Regulation of AMPA receptor lateral movements

Abstract: An essential feature in the modulation of the efficacy of synaptic transmission is rapid changes in the number of AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors at post-synaptic sites on neurons. Regulation of receptor endo- and exocytosis has been shown to be involved in this process. Whether regulated lateral diffusion of receptors in the plasma membrane also participates in receptor exchange to and from post-synaptic sites remains unknown. We analysed the lateral mobility of native AMPA receptors containing the glutamate receptor subunit GluR2 in rat cultured hippocampal neurons, using single-particle tracking and video microscopy. Here we show that AMPA receptors alternate within seconds between rapid diffusive and stationary behaviour. During maturation of neurons, stationary periods increase in frequency and length, often in spatial correlation with synaptic sites. Raising intracellular calcium, a central element in synaptic plasticity, triggers rapid receptor immobilization and local accumulation on the neuronal surface. We suggest that calcium influx prevents AMPA receptors from diffusing, and that lateral receptor diffusion to and from synaptic sites acts in the rapid and controlled regulation of receptor numbers at synapses.

Controlled Ring-Opening Polymerization of Lactones and Lactides Initiated by Lanthanum Isopropoxide, 1. General Aspects and Kinetics

Abstract: Ring-opening polymerization of various lactones and lactides initiated by lanthanum isopropoxide has been investigated. Analysis of molecular weights and molecular-weight distributions of the resulting polymers shows that the ring-opening process is a controlled reaction, which is initiated by a variable number of isopropoxy groups. This number depends on both the monomer and the [monomer]/[initiator] ratio. Kinetic studies indicate that all the polymerizations are equilibrated, and the corresponding thermodynamic parameters and the equilibrium monomer concentrations have been calculated. Comprehensive kinetics carried out for e-caprolactone abd δ-valerolactone polymerizations allows the determination of kinetic order relative to both monomer and initiator concentrations, along with that of the apparent rate constants of polymerization. It is also demonstrated that propagation occurs on aggregated (δ-valerolactone) or unaggregated (e-caprolactone) active polymer chains and that the ring-opening process proceeds via [O-acyl] bond cleavages.

Live benthic foraminiferal faunas from the Bay of Biscay: faunal density, composition, and microhabitats

Abstract: In the meso-oligotrophic Bay of Biscay, a diminishing downward organic matter flux with depth is accompanied by an important decrease of the live foraminiferal density. Although bottom water oxygenation is not directly influenced by organic matter input, the oxygenation of interstitial waters and the primary redox fronts do change in response to variations of the organic matter flux. The occurrence of deep and intermediate infaunal taxa can be linked to fundamental redox fronts and putative associated bacterial consortia. Our data are in agreement with the TROX-model, which explains the benthic foraminiferal microhabitat as a function of organic flux and benthic ecosystem oxygenation. Both the depth of the principle redox fronts and the microhabitat of deep infaunal species show important increases with depth. At the deepest oligotrophic stations, deep infaunal faunas become relatively poor. Therefore, the exported flux of organic matter appears to be the main parameter controlling the composition and the vertical distribution of benthic foraminiferal faunas below the sediment-water interface. The oxygenation of pore waters plays only a minor role. A species-level adaptation of the TROX-model is presented for the Bay of Biscay.

Synchroneity between marine and terrestrial responses to millennial scale climatic variability during the last glacial period in the Mediterranean region

Abstract: Land–sea climatic proxies have been obtained from the Last Glacial section of IMAGES core MD95-2043 (western Mediterranean Sea). Vegetation and alkenone derived SST curves indicate rapid (∼150 years) and synchronous terrestrial and marine climatic changes, paralleling the Dansgaard–Oeschger (D–O) climatic variability over Greenland. This frequency of climate change can be related to shifts between the two modes of operation of the North Atlantic Oscillation (NAO). Transfer functions applied to the pollen data indicate that there was an amplification of the climatic signal during Heinrich events (HEs) in comparison with other D–O stadials. The development and persistence of both Scandinavian and Atlantic Mobile Polar Highs over southwestern Europe may explain the extreme cooling (∼10 °C) and dryness (400 mm) during Heinrich events 5 and 4 in the Mediterranean region. Comparison of the results of core MD95-2043 with similar climatic data from IMAGES core MD95-2042, located off Portugal, indicates that thermal and precipitation gradients occurred between the Mediterranean and the Atlantic sides of Iberia within HEs. HEs 4 and 5 are associated with more humid conditions in the Atlantic (by 200 mm) than in the Mediterranean site, as is the case at the present time. This comparison also illustrates the different behaviour of these areas during the D–O stadials. In contrast with the Mediterranean site, the Atlantic site shows similar precipitation and temperature drops for all the D–O stadials, including those related to the HEs. Here we propose the operation of different Mobile Polar Highs (MPH) as the driving mechanism for this difference in behaviour between the Atlantic and Mediterranean sides of Iberia. HEs are related to a stronger influence of the Scandinavian MPH, forcing a severe aridification and cooling of the full Iberian Peninsula. The Atlantic MPH may have been dominant during the other stadials, which would preferentially affect Southwestern Iberia.

Interaction between glucocorticoid hormones, stress and psychostimulant drugs.

Abstract: In this review we summarize data obtained from animal studies showing that glucocorticoid hormones have a facilitatory role on behavioural responses to psychostimulant drugs such as locomotor activity, self-administration and relapse. These behavioural effects of glucocorticoids involve an action on the meso-accumbens dopamine system, one of the major systems mediating the addictive properties of drugs of abuse. The effects of glucocorticoids in the nucleus accumbens are site-specific; these hormones modify dopamine transmission in only the shell of this nucleus without modifying it in the core. Studies with corticosteroid receptor antagonists suggest that the dopaminergic effects of these hormones depend mostly on glucocorticoid, not on mineralocorticoid receptors. These data suggest that an increase in glucocorticoid hormones, through an action on mesolimbic dopamine neurons, could increase vulnerability to drug abuse. We also discuss the implications of this finding with respect to the physiological role of glucocorticoids. It is proposed that an increase in glucocorticoids, by activating the reward pathway, could counteract the aversive effects of stress. During chronic stress, repeated increases in glucocorticoids and dopamine would result in sensitization of the reward system. This sensitized state, which can persist after the end of the stress, would render the subject more responsive to drugs of abuse and consequently more vulnerable to the development of addiction.

Water‐Soluble Stimuli‐Responsive Vesicles from Peptide‐Based Diblock Copolymers

Abstract: Polypeptide secondary structure controls the dimensions of aggregates formed from a polybutadieneb-poly(L-glutamic acid) diblock copolymer after direct dissolution into water. The hydrodynamic radius (RH) of these aggregates (even at high NaCl concentrations) were found to correlate (see picture) with a transition from a compactly folded α-helical poly(L-glutamic acid) block at low pH to an extended random coil conformation at basic pH.

Benefit of atrial pacing in sleep apnea syndrome.

Abstract: Background Many patients with sleep apnea syndrome have nocturnal bradycardia, paroxysmal tachyarrhythmias, or both, which can be prevented by permanent atrial pacing. We evaluated the effect of using cardiac pacing to increase the heart rate during sleep in patients with sleep apnea syndrome. Methods We studied 15 patients (11 men and 4 women; mean [±SD] age, 69±9 years) with central or obstructive sleep apnea who had received permanent atrial-synchronous ventricular pacemakers for symptomatic sinus bradycardia. All patients underwent three polysomnographic evaluations on consecutive nights, the first night for base-line evaluation and then, in random order, one night in spontaneous rhythm and one in dual-chamber pacing mode with atrial overdrive (basic rate, 15 beats per minute faster than the mean nocturnal sinus rate). The total duration and number of episodes of central or obstructive sleep apnea or hypopnea were analyzed and compared. Results The mean 24-hour sinus rate during spontaneous rhythm was...

Behaviour of Organic Carbon in Nine Contrasting European Estuaries

Abstract: A cross-system comparison of organic carbon origin and behaviour in nine European estuaries is presented. The study sites display a very large range of hydrological and environmental conditions. The watershed of the respective estuaries were characterized by plotting the total organic carbon (TOC) in the rivers versus the inhabitants/discharge ratio. This allows to distinguish four types of watershed with regard to anthropogenic forcing and organic carbon levels: polluted by sewage inputs (Scheldt and to a much lesser extent, Ems, Sado and Thames), decontaminated (Elbe and Rhine), pristine (Gironde and Douro) and eutrophized (Loire and Scheldt). In the estuarine zone, dissolved organic carbon (DOC) almost always decreased linearly with increasing salinity. Exceptions were: the Scheldt, where a net consumption of sewage-derived DOC was observed, the Gironde, where a net production of DOC occurred in the maximum turbidity zone (MTZ) and the Sado and Ems, where DOC was supplied from large intertidal areas. By contrast, a large fraction of the riverine particulate organic carbon (POC) was mineralized in all the estuaries, except the Douro, where residence time of waters is only a few days. A fraction of POC appeared however refractory and accumulated in the MTZs, where terrestrial soil-derived material dominates (Elbe, Ems, Loire, Gironde and Sado). In the marine regions of most estuaries, autochthonous POC was present during spring and summer. The analysis of all river and estuarine data allows estimation of the loss of continental POC occurring in each estuary. It decreases in the following order: Scheldt⪢Thames>Ems=Sado=Loire>Gironde>Elbe>Rhine>Douro, which almost corresponds to the anthropogenic pressure in the respective watersheds. Two major variables appear to control the intensity of this mineralization: the origin of the POC, the lability increasing with pollution, and the residence time of particles in the estuarine zone.

Epidemiology and diagnosis of Helicobacter pylori infection

Abstract: During the period reviewed, prevalence studies were essentially performed in less economically advanced countries and a high prevalence was found. The traditional risk factors for Helicobacter pylori positivity were mostly found. Transmission studied by molecular typing showed a familial transmission. The eventual role of water transmission was explored in several studies with controversial results. Concerning diagnosis, most of the invasive and noninvasive methods used for the diagnosis of H. pylori infection are long standing with efficient performance. The most interesting recent improvements in H. pylori diagnosis include advances in endoscopy, developments in molecular methods, and the introduction of omics-based techniques. Interpretation of old or newer method should take into account the pretest probability and the prevalence of H. pylori in the population under investigation.

Neurobiological evidence for hedonic allostasis associated with escalating cocaine use.

Abstract: A paradoxical aspect of the transition to drug addiction is that drug users spend progressively more time and effort to obtain drug hedonic effects that continually decrease with repeated experience. According to the hedonic allostasis hypothesis, increased craving for and tolerance to the hedonic effects of drugs result from the same chronic alteration in the regulation of brain reward function (allostasis). Here we show in rats that repeated withdrawals from prolonged cocaine self-administration produces a persistent decrease in brain reward function that is highly correlated with escalation of cocaine intake and that reduces the hedonic impact of cocaine.

Bi-allelic inactivation of TCF1 in hepatic adenomas

Abstract: Liver adenomas are benign tumors at risk of malignant transformation. In a genome-wide search for loss of heterozygosity (LOH) associated with liver adenomas, we found a deletion in chromosome 12q in five of ten adenomas. In most cases, LOH at 12q was the only recurrent genetic alteration observed, suggesting the presence of a tumor-suppressor gene in that region. A minimal common region of deletion was defined in 12q24 that included the gene TCF1 (transcription factor 1), encoding hepatocyte nuclear factor 1 (HNF1; refs 1,2). Heterozygous germline mutations of TCF1 have been identified in individuals affected with maturity-onset diabetes of the young type 3 (MODY3; ref. 3). Bi-allelic inactivation of TCF1 was found in 10 of 16 screened adenomas, and heterozygous germline mutation were present in three affected individuals. Furthermore, 2 well-differentiated hepatocellular carcinomas (HCCs) occurring in normal liver contained somatic bi-allelic mutations of 30 screened HCCs. These results indicate that inactivation of TCF1, whether sporadic or associated with MODY3, is an important genetic event in the occurrence of human liver adenoma, and may be an early step in the development of some HCCs.

Bottom currents, contourites and deep-sea sediment drifts: current state-of-the-art

Abstract: This paper provides both an introduction to and summary for the Atlas of Contourite Systems that has been compiled as part of the International Geological Correlation Project - IGCP 432. Following the seminal works of George Wust on the physical oceanography of bottom currents, and Charley Hollister on contourite sediments, a series of significant advances have been made over the past few decades. While accepting that ideas and terms must remain flexible as our knowledge base continues to increase, we present a consensus view on terminology and definitions of bottom currents, contourites and drifts. Both thermohaline and wind-driven circulation, influenced by Coriolis Force and molded by topography, contribute to the oceanic system of bottom currents. These semi-permanent currents show significant variability in time and space, marked by periodic benthic storm events in areas of high surface kinetic energy. Six different drift types are recognized in the ocean basins and margins at depths greater than about 300 m: (i) contourite sheet drifts; (ii) elongate mounded drifts; (iii) channel related drifts; (iv) confined drifts; (v) infill drifts; and (vi) modified drift-turbidite systems. In addition to this overall geometry, their chief seismic characteristics include: a uniform reflector pattern that reflects long-term stability, drift-wide erosional discontinuities caused by periodic changes in bottom current regime, and stacked broadly lenticular seismic depositional units showing oblique to downcurrent migration. At a smaller scale, a variety of seismic facies can be recognized that are here related to bottom current intensity. A model for seismic facies cyclicity (alternating transparent/reflector zones) is further elaborated, and linked to bottom current/climate change. Both erosional features and depositional bedforms are diagnostic of bottom current systems and velocities. Many different contourite facies are now known to exist, encompassing all compositional types. We propose here a Cl-5 notation for the standard contourite facies sequence, which can be interpreted in terms of fluctuation in bottom current velocity and/or sediment supply. Several proxies can be utilized to decode contourite successions in terms of current fluctuation. Gravel lag and shale chip contourites, as well as erosional discontinuities are indicative of still greater velocities. There are a small but growing number of land-based examples of fossil contourites, based on careful analysis using the recommended three-stage approach to interpretation. Debate still surrounds the recognition and interpretation of bottom current reworked turbidites.

The role of ketamine in preventing fentanyl-induced hyperalgesia and subsequent acute morphine tolerance.

Abstract: Perioperative opioids increase postoperative pain and morphine requirement, suggesting acute opioid tolerance. Furthermore, opioids elicit N-methyl-d-aspartate (NMDA)-dependent pain hypersensitivity. We investigated postfentanyl morphine analgesic effects and the consequences of NMDA-receptor antago

Comparison of characteristics in responders versus nonresponders with biventricular pacing for drug-resistant congestive heart failure

Abstract: This prospective study confirmed the long-term beneficial hemodynamic and clinical effects of cardiac resynchronization in patients with severe congestive heart failure and a major left intraventricular conduction delay. Patients who are not improved are likely to have had a myocardial infarction, a low cardiac output, and no significant mitral regurgitation.

Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean during the North Atlantic cold events of the past 50 k.y.

Abstract: Multiproxy paleoenvironmental records (pollen and planktonic isotope) from Ocean Drilling Program Site 976 (Alboran Sea) document rapid ocean and climate variations during the last glacial that follow the Dansgaard-Oeschger climate oscillations seen in the Greenland ice core records, thus suggesting a close link of the Mediterranean climate swings with North Atlantic climates. Continental conditions rapidly oscillated through cold-arid and warm-wet conditions in the course of stadial-interstadial climate jumps. At the time of Heinrich events, i.e., maximum meltwater flux to the North Atlantic, western Mediterranean marine microflora and microfauna show rapid cooling correlated with increasing continental dryness. Enhanced aridity conceivably points to prolonged wintertime stability of atmospheric high-pressure systems over the southwestern Mediterranean in conjunction with cooling of the North Atlantic.