Showing papers by "Pierre-and-Marie-Curie University published in 2005"

Diagnosis and management of dementia with Lewy bodies: Third report of the DLB Consortium

Abstract: The dementia with Lewy bodies (DLB) Consortium has revised criteria for the clinical and pathologic diagnosis of DLB incorporating new information about the core clinical features and suggesting improved methods to assess them. REM sleep behavior disorder, severe neuroleptic sensitivity, and reduced striatal dopamine transporter activity on functional neuroimaging are given greater diagnostic weighting as features suggestive of a DLB diagnosis. The 1-year rule distinguishing between DLB and Parkinson disease with dementia may be difficult to apply in clinical settings and in such cases the term most appropriate to each individual patient should be used. Generic terms such as Lewy body (LB) disease are often helpful. The authors propose a new scheme for the pathologic assessment of LBs and Lewy neurites (LN) using alpha-synuclein immunohistochemistry and semiquantitative grading of lesion density, with the pattern of regional involvement being more important than total LB count. The new criteria take into account both Lewy-related and Alzheimer disease (AD)-type pathology to allocate a probability that these are associated with the clinical DLB syndrome. Finally, the authors suggest patient management guidelines including the need for accurate diagnosis, a target symptom approach, and use of appropriate outcome measures. There is limited evidence about specific interventions but available data suggest only a partial response of motor symptoms to levodopa: severe sensitivity to typical and atypical antipsychotics in ∼50%, and improvements in attention, visual hallucinations, and sleep disorders with cholinesterase inhibitors.

Signal recovery by proximal forward-backward splitting ∗

Abstract: We show that various inverse problems in signal recovery can be formulated as the generic problem of minimizing the sum of two convex functions with certain regularity properties. This formulation makes it possible to derive existence, uniqueness, characterization, and stability results in a unified and standardized fashion for a large class of apparently disparate problems. Recent results on monotone operator splitting methods are applied to establish the convergence of a forward-backward algorithm to solve the generic problem. In turn, we recover, extend, and provide a simplified analysis for a variety of existing iterative methods. Applications to geometry/texture image decomposition schemes are also discussed. A novelty of our framework is to use extensively the notion of a proximity operator, which was introduced by Moreau in the 1960s.

A tutorial on onset detection in music signals

Abstract: Note onset detection and localization is useful in a number of analysis and indexing techniques for musical signals. The usual way to detect onsets is to look for "transient" regions in the signal, a notion that leads to many definitions: a sudden burst of energy, a change in the short-time spectrum of the signal or in the statistical properties, etc. The goal of this paper is to review, categorize, and compare some of the most commonly used techniques for onset detection, and to present possible enhancements. We discuss methods based on the use of explicitly predefined signal features: the signal's amplitude envelope, spectral magnitudes and phases, time-frequency representations; and methods based on probabilistic signal models: model-based change point detection, surprise signals, etc. Using a choice of test cases, we provide some guidelines for choosing the appropriate method for a given application.

Central nervous system injury-induced immune deficiency syndrome

Abstract: Infections are a leading cause of morbidity and mortality in patients with acute CNS injury. It has recently become clear that CNS injury significantly increases susceptibility to infection by brain-specific mechanisms: CNS injury induces a disturbance of the normally well balanced interplay between the immune system and the CNS. As a result, CNS injury leads to secondary immunodeficiency - CNS injury-induced immunodepression (CIDS) - and infection. CIDS might serve as a model for the study of the mechanisms and mediators of brain control over immunity. More importantly, understanding CIDS will allow us to work on developing effective therapeutic strategies, with which the outcome after CNS damage by a host of diseases could be improved by eliminating a major determinant of poor recovery.

Theoretical evaluation of electron delocalization in aromatic molecules by means of atoms in molecules (AIM) and electron localization function (ELF) topological approaches.

Abstract: Benzene is the emblematic example of an aromatic molecule, and the problem of its structure has given rise to a chemical serial story running over several decades. The epistemological digest of this story written by Stephen G. Brush1,2 shows how this problem has been at the root of important concepts such as those of mesomery and resonance. Before the advent of quantum mechanics, chemists had thought of the benzene structures in terms of two center bonds attempting to preserve the valence of the carbon atom and to explain its chemical properties. Kekulé’s theory of the structure of the benzene molecule3 invokes the oscillatory hypothesis in which “the fourth valence of each carbon oscillates between its neighbors, synchronously with all the other fourth valences, so that the structure switches rapidly between the two structures”,1 whereas Claus proposed a diagonal hypothesis4 in which the fourth valence of each carbon is directed toward the carbon in the para position. The latter hypothesis has been rejected because it enables only two derivatives, and it has been revised to remove this inconsistency: instead of forming a bond, the fourth valence stops near the center of the ring in the Armstrong-Baeyer formula,5 or there is only one bridging bond as in the Dewar’s bridged benzene formula.6 In Thiele’s partial valence model,7 the adjacent carbon-carbon bonds are considered as intermediate between single and double bonds. These formulas were later considered by K. C. Ingold to set up his intra-annular tautomerism,8 which appears to be the generalization of Kekulé’s oscillatory hypothesis. Ingold’s tautomerism hypothesis was later called mesomerism.9 The mesomery is an important concept in chemistry, which implicitly introduces the electron delocalization in the context of the prequantum electronic theory. The first applications of quantum chemistry to the benzene problem led on the molecular orbital (MO) side Erich Hückel to propose his famous 4n + 2 rule10 and on the valence bond (VB) side Pauling and Wheland to identify resonance with Ingold’s mesomerism.11,12 An enlighting contribution of modern VB theory on the benzene structure has been brought by Shaik et al.,13 who have shown that the hexagonal symmetry of benzene is due to the σ-system because the π component is distortive along a Kekulean distortion. * Authors to whom correspondence should be addressed (telephone +34-972-418912; fax +34-972-418356; e-mail miquel.sola@ udg.es or silvi@lct.jussieu.fr). ‡ Universitat de Girona. § Université Pierre et Marie Curie. 3911 Chem. Rev. 2005, 105, 3911−3947

Towards standardization of RNA quality assessment using user-independent classifiers of microcapillary electrophoresis traces

Abstract: While it is universally accepted that intact RNA constitutes the best representation of the steady-state of transcription, there is no gold standard to define RNA quality prior to gene expression analysis. In this report, we evaluated the reliability of conventional methods for RNA quality assessment including UV spectroscopy and 28S:18S area ratios, and demonstrated their inconsistency. We then used two new freely available classifiers, the Degradometer and RIN systems, to produce user-independent RNA quality metrics, based on analysis of microcapillary electrophoresis traces. Both provided highly informative and valuable data and the results were found highly correlated, while the RIN system gave more reliable data. The relevance of the RNA quality metrics for assessment of gene expression differences was tested by Q-PCR, revealing a significant decline of the relative expression of genes in RNA samples of disparate quality, while samples of similar, even poor integrity were found highly comparable. We discuss the consequences of these observations to minimize artifactual detection of false positive and negative differential expression due to RNA integrity differences, and propose a scheme for the development of a standard operational procedure, with optional registration of RNA integrity metrics in public repositories of gene expression data.

Epimutation of the telomeric imprinting center region on chromosome 11p15 in Silver-Russell syndrome

Abstract: Silver-Russell syndrome (SRS, OMIM 180860) is a congenital disorder characterized by severe intrauterine and postnatal growth retardation, dysmorphic facial features and body asymmetry. SRS is genetically heterogenous with maternal uniparental disomy with respect to chromosome 7 occurring in approximately 10% of affected individuals. Given the crucial role of the 11p15 imprinted region in the control of fetal growth, we hypothesized that dysregulation of genes at 11p15 might be involved in syndromic intrauterine growth retardation. We identified an epimutation (demethylation) in the telomeric imprinting center region ICR1 of the 11p15 region in several individuals with clinically typical SRS. This epigenetic defect is associated with, and probably responsible for, relaxation of imprinting and biallelic expression of H19 and downregulation of IGF2. These findings provide new insight into the pathogenesis of SRS and strongly suggest that the 11p15 imprinted region, in addition to those of 7p11.2-p13 and 7q31-qter, is involved in SRS.

The international registry on hand and composite tissue transplantation

Abstract: The first hand transplantation was performed in Lyon, France, on 23 September 1998 by an international team of surgeons [1]. Since then, hand transplantation programmes have been launched in the United States, Austria, China, Italy, Belgium and Poland [2, 3, 4, 5, 6], and the teams felt the need to create a worldwide registry to provide a basis for cooperation and to share their experiences (Fig. 1). Since May 2002, all groups [7] performing hand transplantations have supplied detailed information to the International Registry on Hand and Composite Tissue Transplantation (IRHCTT; www.handregistry.com). Follow-up period ranged from 2 to 85 months (Table 1). A good number of composite tissue transplantations other than the hand have been performed around the world in the period 1994–2006, including the femoral diaphysis, the knee, the larynx, the uterus, the abdominal wall, a lower limb in conjoined twins, and most recently, the face in two centres.

Global Natural Regulatory T Cell Depletion in Active Systemic Lupus Erythematosus

Abstract: The immune defect that could account for the multisystemic involvement that characterizes systemic lupus erythematosus (SLE) remains unknown. We hypothesized that iterative disease flares correspond to a recurrent defect in the peripheral immune suppression exerted by naturally occurring T regulatory cells (Tregs). Surprisingly, Tregs isolated from lupus patients show the same phenotypic and functional characteristics as corresponding cells found in healthy controls. A decrease in the proportion of circulating Tregs among other CD4+ T cells is nevertheless evidenced in active patients when this group is compared with healthy controls (0.57 +/- 0.24%, n = 45 vs 1.29 +/- 0.38%, n = 82, p < 0.0001) or with inactive patients (1.22 +/- 0.67%, n = 62, p < 0.0001). In contrast, the proportion of Tregs in other systemic autoimmune diseases such as primary Sjogren syndrome and inflammatory myopathy does not significantly differ from controls' values (1.15 +/- 0.46%, n = 21, p = 0.09 and 1.16 +/- 0.44%, n = 16, p = 0.43, respectively). Lupus Tregs do not accumulate in either the lymph nodes or the diseased kidneys and are not killed by a circulating soluble factor, but demonstrate in vitro a heightened sensitivity to Fas-induced apoptosis. Finally, we show that the extent of Treg depletion correlates with the clinical severity of the flare. SLE flares are therefore associated with a global Treg depletion and not with a phenomenon of tissue redistribution. In summary, we suggest that the physiopathology of SLE could be tied to a defect in the homeostatic control of the Treg subpopulation.

Mechanical properties of hybrid organic–inorganic materials

Abstract: Homogeneously dispersed organic–inorganic hybrid nanocomposites can be obtained by increasing the interfacial interactions between both components via the formation of hydrogen bonds or covalent bonds, by mixing various polymers or via the adequate choice of the inorganic precursors The mechanical response of these advanced functional materials is an issue of paramount importance when industrial applications are targeted Large progress in the understanding of the mechanical properties of O–I hybrids has been gained by testing these materials under different conditions (static and dynamic, low and large deformations up to fracture) and using specific techniques developed for the mechanical characterization of conventional materials such as polymers, glasses or ceramics However, the mechanical properties of hybrid O–I materials are dependent on their micro- and nanostructures and on the nature and extent of the O–I interfaces Consequently, predictable mechanical properties for hybrids still represent a major challenge for hybrid materials science Industrial attraction for hybrid materials has been emphasized by the development of new functional coatings An important issue is the interface between the film and the substrate since strong adhesion can be tailored and ensures that delamination of the film will be limited

Prevalence of Drug-Resistant HIV-1 Variants in Untreated Individuals in Europe: Implications for Clinical Management

Abstract: BackgroundInfection with drug-resistant human immunodeficiency virus type 1 (HIV-1) can impair the response to combination therapy. Widespread transmission of drug-resistant variants has the disturbing potential of limiting future therapy options and affecting the efficacy of postexposure prophylaxispenta increase-spacing 1>MethodsWe determined the baseline rate of drug resistance in 2208 therapy-naive patients recently and chronically infected with HIV-1 from 19 European countries during 1996–2002ResultsIn Europe, 1 of 10 antiretroviral-naive patients carried viruses with ⩾1 drug-resistance mutation. Recently infected patients harbored resistant variants more often than did chronically infected patients (13.5% vs. 8.7%; P=.006). Non-B viruses (30%) less frequently carried resistance mutations than did subtype B viruses (4.8% vs. 12.9%; P<.01). Baseline resistance increased over time in newly diagnosed cases of non-B infection: from 2.0% (1/49) in 1996–1998 to 8.2% (16/194) in 2000–2001ConclusionsDrug-resistant variants are frequently present in both recently and chronically infected therapy-naive patients. Drug-resistant variants are most commonly seen in patients infected with subtype B virus, probably because of longer exposure of these viruses to drugs. However, an increase in baseline resistance in non-B viruses is observed. These data argue for testing all drug-naive patients and are of relevance when guidelines for management of postexposure prophylaxis and first-line therapy are updated

Generation of Superparamagnetic Liposomes Revealed as Highly Efficient MRI Contrast Agents for in Vivo Imaging

Abstract: Maghemite (gamma-Fe2O3) nanocrystals stable at neutral pH and in isotonic aqueous media were synthesized and encapsulated within large unilamellar vesicles of egg phosphatidylcholine (EPC) and distearoyl-SN-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000] (DSPE-PEG(2000), 5 mol %), formed by film hydration coupled with sequential extrusion. The nonentrapped particles were removed by flash gel exclusion chromatography. The magnetic-fluid-loaded liposomes (MFLs) were homogeneous in size (195 +/- 33 hydrodynamic diameters from quasi-elastic light scattering). Iron loading was varied from 35 up to 167 Fe(III)/lipid mol %. Physical and superparamagnetic characteristics of the iron oxide particles were preserved after liposome encapsulation as shown by cryogenic transmission electron microscopy and magnetization curve recording. In biological media, MFLs were highly stable and avoided ferrofluid flocculation while being nontoxic toward the J774 macrophage cell line. Moreover, steric stabilization ensured by PEG-surface-grafting significantly reduced liposome association with the macrophages. The ratios of the transversal (r2) and longitudinal (r1) magnetic resonance (MR) relaxivities of water protons in MFL dispersions (6 < r2/r1 < 18) ranked them among the best T2 contrast agents, the higher iron loading the better the T2 contrast enhancement. Magnetophoresis demonstrated the possible guidance of MFLs by applying a magnetic field gradient. Mouse MR imaging assessed MFLs efficiency as contrast agents in vivo: MR angiography performed 24 h after intravenous injection of the contrast agent provided the first direct evidence of the stealthiness of PEG-ylated magnetic-fluid-loaded liposomes.

Polyoxometalates: introduction to a class of inorganic compounds and their biomedical applications.

Abstract: An increasing number of potential applications for polyoxometalates in human medicine have been reported in the literature. These inorganic complexes are composed of early transition metals (mainly molybdenum, tungsten and vanadium) and oxygen. The present review gives an introduction into the chemistry of these compounds, and an overview of the principal studies of their biological and biochemical effects and their therapeutic potential. The reported antitumoral and antibiotic properties of molybdates and tungstates in vitro and in vivo are compiled and discussed, as are their influences on the blood glucose level in diabetic animals. Aspects of antiviral activities and cell penetration are treated.

Dealing with spatial heterogeneity

Abstract: Heterogeneity can be dealt with by defining homogeneous equivalent properties, known as averaging, or by trying to describe the spatial variability of the rock properties from geologic observations and local measurements. The techniques available for these descriptions are mostly continuous Geostatistical models, or discontinuous facies models such as the Boolean, Indicator or Gaussian-Threshold models and the Markov chain model. These facies models are better suited to treating issues of rock strata connectivity, e.g. buried high permeability channels or low permeability barriers, which greatly affect flow and, above all, transport in aquifers. Genetic models provide new ways to incorporate more geology into the facies description, an approach that has been well developed in the oil industry, but not enough in hydrogeology. The conclusion is that future work should be focused on improving the facies models, comparing them, and designing new in situ testing procedures (including geophysics) that would help identify the facies geometry and properties. A world-wide catalog of aquifer facies geometry and properties, which could combine site genesis and description with methods used to assess the system, would be of great value for practical applications.

The frustration-based approach of supercooled liquids and the glass transition: a review and critical assessment

Abstract: One of the most spectacular phenomena in physics in terms of dynamical range is the glass transition and the associated slowing down of flow and relaxation with decreasing temperature. That it occurs in many different liquids seems to call for a 'universal' theory. In this article, we review one such theoretical approach, which is based on the concept of 'frustration'. Frustration in this context describes an incompatibility between extension of the locally preferred order in a liquid and tiling of the whole space. We provide a critical assessment of what has been achieved within this approach and we discuss its relation with other theories of the glass transition.

Porosity and Mechanical Properties of Mesoporous Thin Films Assessed by Environmental Ellipsometric Porosimetry

Abstract: Mesoordered silica thin films with cubic structures were prepared by evaporation induced self-assembly (EISA) with two types of structuring agent (CTAB and block copolymer F127). A complete and accurate description of these films was obtained by combining 2D-SAXS analyses, variable angle spectroscopic ellipsometry, and a specially designed environmental ellipsometric porosimetry (EEP) experiment. The EEP analysis is rapid and cheap and operates at ambient pressure and temperature. This latter experiment was performed with water and produced a set of water adsorption-desorption isotherms. A modified Kelvin equation, coupled with a modelisation of pores contraction, enabled the determination of the structural parameters of films porous networks: ellipsoidal pore diameters, porous volume, and surface area. Young moduli of films in the direction perpendicular to the substrates were calculated from these parameters.

Malarial parasites decrease reproductive success: an experimental study in a passerine bird

Abstract: Malarial parasites are supposed to have strong negative fitness consequences for their hosts, but relatively little evidence supports this claim due to the difficulty of experimentally testing this. We experimentally reduced levels of infection with the blood parasite Haemoproteus prognei in its host the house martin Delichon urbica, by randomly treating adults with primaquine or a control treatment. Treated birds had significantly fewer parasites than controls. The primaquine treatment increased clutch size by 18%; hatching was 39% higher and fledging 42% higher. There were no effects of treatment on quality of offspring, measured in terms of tarsus length, body mass, haematocrit or T-cell-mediated immune response. These findings demonstrate that malarial parasites can have dramatic effects on clutch size and other demographic variables, potentially influencing the evolution of clutch size, but also the population dynamics of heavily infected populations of birds.

Poor Intraoperative Blood Glucose Control Is Associated with a Worsened Hospital Outcome after Cardiac Surgery in Diabetic Patients

Abstract: Background:Tight perioperative control of blood glucose improves the outcome of diabetic patients undergoing cardiac surgery. Because stress response and cardiopulmonary bypass can induce profound hyperglycemia, intraoperative glycemic control may become difficult. The authors undertook a prospectiv

Response of diatoms distribution to global warming and potential implications: A global model study

Abstract: Using a global model of ocean biogeochemistry coupled to a climate model, we explore the effect of climate change on the distribution of diatoms, a key phytoplankton functional group. Our model results suggest that climate change leads to more nutrient-depleted conditions in the surface ocean and that it favors small phytoplankton at the expense of diatoms. At 4xCO 2 , diatoms relative abundance is reduced by more than 10% at the global scale and by up to 60% in the North Atlantic and in the subantarctic Pacific. This simulated change in the ecosystem structure impacts oceanic carbon uptake by reducing the efficiency of the biological pump, thus contributing to the positive feedback between climate change and the ocean carbon cycle. However, our model simulations do not identify this biological mechanism as a first-order process in the response of ocean carbon uptake to climate change

Evidence for Multiple Reversals of Asymmetric Mutational Constraints during the Evolution of the Mitochondrial Genome of Metazoa, and Consequences for Phylogenetic Inferences

Abstract: Mitochondrial DNA (mtDNA) sequences are commonly used for inferring phylogenetic relationships. However, the strand-specific bias in the nucleotide composition of the mtDNA, which is thought to reflect asymmetric mutational constraints, combined with the important compositional heterogeneity among taxa, are known to be highly problematic for phylogenetic analyses. Here, nucleotide composition was compared across 49 species of Metazoa (34 arthropods, 2 annelids, 2 molluscs, and 11 deuterosomes), and analyzed for a mtDNA fragment including six protein-coding genes, i.e., atp6, atp8, cox1, cox2, cox3, and nad2. The analyses show that most metazoan species present a clear strand asymmetry, where one strand is biased in favor of A and C, whereas the other strand has a reverse bias, i.e., in favor of T and G. The origin of this strand bias can be related to asymmetric mutational constraints involving deaminations of A and C nucleotides during the replication and/or transcription processes. The analyses reveal that six unrelated genera are characterized by a reversal of the usual strand bias, i.e., Argiope (Araneae), Euscorpius (Scorpiones), Tigriopus (Maxillopoda), Branchiostoma (Cephalochordata), Florometra (Echinodermata), and Katharina (Mollusca). It is proposed that asymmetric mutational constraints have been independently reversed in these six genera, through an inversion of the control region, i.e., the region that contains most regulatory elements for replication and transcription of the mtDNA. We show that reversals of asymmetric mutational constraints have dramatic consequences on the phylogenetic analyses, as taxa characterized by reverse strand bias tend to group together due to long-branch attraction artifacts. We propose a new method for limiting this specific problem in tree reconstruction under the Bayesian approach. We apply our method to deal with the question of phylogenetic relationships of the major lineages of Arthropoda. This new approach provides a better congruence with nuclear analyses based on 18S rRNA gene sequences. By contrast with some previous studies based on mtDNA sequences, our data suggest that Chelicerata, Crustacea, Myriapoda, Pancrustacea, and Paradoxopoda are monophyletic. (Arthropoda; asymmetry; genome; long-branch attraction artifact; mitochondria; molecular evolution; mutations; phylogeny; strand bias.)

QCD Predictions for Charm and Bottom Quark Production at RHIC

Abstract: We make up-to-date QCD predictions for open charm and bottom production at RHIC in nucleon-nucleon collisions at {radical}S = 200 GeV. We also calculate the electron spectrum resulting from heavy flavor decays to allow direct comparison to the data. A rigorous benchmark, including the theoretical uncertainties, is established against which nuclear collision data can be compared to obtain evidence for nuclear effects.

Superconductivity of bulk CaC6.

Abstract: We have obtained bulk samples of the graphite intercalation compound, CaC6, by a novel method of synthesis from highly oriented pyrolytic graphite. The crystal structure has been completely determined showing that it is the only member of the MC6, metal-graphite compounds that has rhombohedral symmetry. We have clearly shown the occurrence of superconductivity in the bulk sample at 11.5 K, using magnetization measurements.

Study of the B- → J/ΨK -π+π- decay and measurement of the B - → X(3872)K- branching fraction

Abstract: The authors study the decay B{sup -} {yields} J/{psi}K{sup -}{pi}{sup +}{pi}{sup -} using 117 million B{bar B} events collected at the {Upsilon}(4S) resonance with the BaBar detector at the PEP-II e{sup +}e{sup -} asymmetric-energy storage ring. They measure the branching fractions {Beta}(B{sup -} {yields} J/{psi}K{sup -} {pi}{sup +}{pi}{sup -}) = (116 {+-} 7(stat.) {+-} 9(syst.)) x 10{sup -5} and {Beta}(B{sup -} {yields} X(3872)K{sup -}) x {Beta}(X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -}) = (1.28 {+-} 0.41) x 10{sup -5} and find the mass of the X(3872) to be 3873.4 {+-} 1.4MeV/c{sup 2}. They search for the h{sub c} narrow state in the decay B{sup -} {yields} h{sub c} K{sup -}, h{sub c} {yields} J/{psi}{pi}{sup +}{pi}{sup -} and for the decay B{sup -} {yields} J/{psi}D{sup 0}{pi}{sup -}, with D{sup 0} {yields} K{sup -}{pi}{sup +}. They set the 90% C.L. limits {Beta}(B{sup -} {yields} h{sub c}K{sup -}) x {Beta}(h{sub c} {yields} J/{psi}{pi}{sup +}{pi}{sup -}) < 3.4 x 10{sup -6} and {Beta}(B{sup -} {yields} J/{psi}D{sup 0}{pi}{sup -}) < 5.2 x 10{sup -5}.

Computational Methods for Option Pricing

Abstract: Preface 1. Option pricing 2. Black-Scholes equation mathematical analysis 3. Finite differences 4. The finite element method 5. Adaptive mesh refinement 6. American options 7. Sensitivities and calibration 8. Calibration of local volatility with European options 9. Calibration of local volatility with American options Bibliography Index.