830 research outputs found

    Clinical implication of FMR1 intermediate alleles in a Spanish population

    Get PDF
    FMR1 premutation carriers (55-200 CGGs) are at risk of developing Fragile X-associated primary ovarian insufficiency as well as Fragile X-associated tremor/ataxia syndrome. FMR1 premutation alleles are also associated with a variety of disorders, including psychiatric, developmental, and neurological problems. However, there is a major concern regarding clinical implications of smaller CGG expansions known as intermediate alleles (IA) or gray zone alleles (45-54 CGG). Although several studies have hypothesized that IA may be involved in the etiology of FMR1 premutation associated phenotypes, this association still remains unclear. The aim of this study was to provide new data on the clinical implications of IA. We reviewed a total of 17 011 individuals: 1142 with primary ovarian insufficiency, 478 with movement disorders, 14 006 with neurodevelopmental disorders and 1385 controls. Similar IA frequencies were detected in all the cases and controls (cases 1.20% vs controls 1.39%, P =.427). When comparing the allelic frequencies of IA = 50CGGs, a greater, albeit not statistically significant, number of alleles were detected in all the cohorts of patients. Therefore, IA below 50 CGGs should not be considered as risk factors for FMR1 premutation-associated phenotypes, at least in our population. However, the clinical implication of IA = 50CGGs remains to be further elucidated

    Seed degeneration of banana planting materials: strategies for improved farmer access to healthy seed

    Get PDF
    Vegetatively propagated crops suffer from yield loss and reduced stand density and longevity caused by the build‐up of certain pests and pathogens between successive plantings via infected planting material. Here, six seedborne phytosanitary problems of banana are reviewed to evaluate whether a seed degeneration framework is a useful tool to identify approaches to achieve healthier planting materials. Phytoparasitic nematodes and weevils generate gradual declines in yields and in sucker health. Fusarium wilt and banana bunchy top virus cause progressive mat collapse across the field. Symptomless suckers from any mat in infested fields represent a risk of transmitting the disease to a new field. Xanthomonas and ralstonia wilts, due to incomplete systemicity, are intermediate in their threat to yield loss and frequency of transmission in suckers. Losses to banana streak virus are triggered by abiotic stress, although sucker transmission of episomal banana streak virus also contributes. A qualitative equation described here for seed degeneration covers a cycle beginning with the quality and risk factors of the planting material used to plant a new field and ends with the quality and risk factors of the suckers extracted from the field to plant a new field. This review of five planting material multiplication methods commonly used in banana contrasts their differing usefulness to address seed degeneration in the small farm context. It is proposed that initiatives to offset banana seed degeneration should integrate the role of off‐farm actors into decentralized initiatives rather than attempt to duplicate national seed certification frameworks from other true seed or vegetatively propagated crops

    The geometry of spontaneous spiking in neuronal networks

    Full text link
    The mathematical theory of pattern formation in electrically coupled networks of excitable neurons forced by small noise is presented in this work. Using the Freidlin-Wentzell large deviation theory for randomly perturbed dynamical systems and the elements of the algebraic graph theory, we identify and analyze the main regimes in the network dynamics in terms of the key control parameters: excitability, coupling strength, and network topology. The analysis reveals the geometry of spontaneous dynamics in electrically coupled network. Specifically, we show that the location of the minima of a certain continuous function on the surface of the unit n-cube encodes the most likely activity patterns generated by the network. By studying how the minima of this function evolve under the variation of the coupling strength, we describe the principal transformations in the network dynamics. The minimization problem is also used for the quantitative description of the main dynamical regimes and transitions between them. In particular, for the weak and strong coupling regimes, we present asymptotic formulas for the network activity rate as a function of the coupling strength and the degree of the network. The variational analysis is complemented by the stability analysis of the synchronous state in the strong coupling regime. The stability estimates reveal the contribution of the network connectivity and the properties of the cycle subspace associated with the graph of the network to its synchronization properties. This work is motivated by the experimental and modeling studies of the ensemble of neurons in the Locus Coeruleus, a nucleus in the brainstem involved in the regulation of cognitive performance and behavior

    Polarization phenomena in open charm photoproduction processes

    Get PDF
    We analyze polarization effects in associative photoproduction of pseudoscalar (Dˉ\bar{D}) charmed mesons in exclusive processes γ+NYc+Dˉ\gamma+ N\to Y_c +\bar{D}, Yc=Λc+Y_c=\Lambda_c^+, Σc\Sigma_c. Circularly polarized photons induce nonzero polarization of the YcY_c-hyperon with xx- and zz-components (in the reaction plane) and non vanishing asymmetries Ax{\cal A}_x and Az{\cal A}_z for polarized nucleon target. These polarization observables can be predicted in model-independent way for exclusive Dˉ\bar{D}-production processes in collinear kinematics. The T-even YcY_c-polarization and asymmetries for non-collinear kinematics can be calculated in framework of an effective Lagrangian approach. The depolarization coefficients DabD_{ab}, characterizing the dependence of the YcY_c-polarization on the nucleon polarization are also calculated.Comment: 36 pages 13 figure

    Resummation of the Divergent Perturbation Series for a Hydrogen Atom in an Electric Field

    Get PDF
    We consider the resummation of the perturbation series describing the energy displacement of a hydrogenic bound state in an electric field (known as the Stark effect or the LoSurdo-Stark effect), which constitutes a divergent formal power series in the electric field strength. The perturbation series exhibits a rich singularity structure in the Borel plane. Resummation methods are presented which appear to lead to consistent results even in problematic cases where isolated singularities or branch cuts are present on the positive and negative real axis in the Borel plane. Two resummation prescriptions are compared: (i) a variant of the Borel-Pade resummation method, with an additional improvement due to utilization of the leading renormalon poles (for a comprehensive discussion of renormalons see [M. Beneke, Phys. Rep. vol. 317, p. 1 (1999)]), and (ii) a contour-improved combination of the Borel method with an analytic continuation by conformal mapping, and Pade approximations in the conformal variable. The singularity structure in the case of the LoSurdo-Stark effect in the complex Borel plane is shown to be similar to (divergent) perturbative expansions in quantum chromodynamics.Comment: 14 pages, RevTeX, 3 tables, 1 figure; numerical accuracy of results enhanced; one section and one appendix added and some minor changes and additions; to appear in phys. rev.

    Enfermedades causantes de abortos en cabras.

    Get PDF
    Se determinaron los títulos de anticuerpos de las siguientes enfermedades causantes de abortos en cabras de la sabana de Bogotá: brucelosis (asumiendo una reacción cruzada con Brucella melitensis), clamidiosis, letospirosis y toxoplasmosis. Un total de 200 muestras fueron analizadas, tomadas en 21 apriscos con una población de 1.033 animales. Para el primer caso, se encontró el 3.5 por ciento de reactores a Brucella abortus por medio de la prueba lenta en tubo (título 1:200), corroborando esta reactividad por medio de la prueba de mercaptoetanol (1:50) y fijación de complemento (1:64). Para determinar anticuerpos fijadores de complemento para Chlamydia psittachi, se comprobó que el uno por ciento fueron reactores con un rango de confianza del 95 por ciento y prueba diagnóstica específica para Chlamydia. En la leptospirosis se halló una prevalencia instantánea del 4 por ciento que representa los animales reactores. Unicamente 2 animales presentaron títulos de 1:100 y 1:400 para Leptospira icterohaemorrhagie. Las pruebas para toxoplasmosis mostraron que el 25 por ciento de los animales analizados fueron reactores a Toxoplasma gondi

    Predictive factors and early biomarkers of response in multiple sclerosis patients treated with natalizumab

    Get PDF
    There are an increasing number of treatments available for multiple sclerosis (MS). The early identification of optimal responders to individual treatments is important to achieve individualized therapy. With this aim, we performed a multicenter retrospective longitudinal study including 186 MS patients treated with natalizumab who were followed for 2 years. We analyzed the following variables at recruitment: sex, current age, age at disease onset, disease duration, EDSS, number of T2 and Gd + lesions, IgG and IgM oligoclonal bands, HLA class II (DR, DRB, DQA, DQB, and DRB1*15:01), IgG and IgM antibody titers against human herpesvirus 6 (HHV-6) and the antibody response to Epstein–Barr virus (EBV) through the measurement of the anti-EBNA-1 and anti-VCA IgG titers, in relation to clinical response (no relapses or disability progression), and to NEDA-3 (no evidence of disease activity in terms of clinical response and no changes in MRI scans either) after 2-years follow-up. Baseline EDSS score, baseline EBNA-1 IgG titers and percentage change of HHV6 IgG titers between baseline and 6 month visits were significantly different in clinical responders and in NEDA-3 status (all of them remained significant in the multivariate analysis). We identified three variables for the early identification of natalizumab optimal responders in a rapid and cost-effective approach
    corecore