382 research outputs found

    High Levels of Diversity Uncovered in a Widespread Nominal Taxon: Continental Phylogeography of the Neotropical Tree Frog

    Get PDF
    Species distributed across vast continental areas and across major biomes provide unique model systems for studies of biotic diversification, yet also constitute daunting financial, logistic and political challenges for data collection across such regions. The tree frog Dendropsophus minutus (Anura: Hylidae) is a nominal species, continentally distributed in South America, that may represent a complex of multiple species, each with a more limited distribution. To understand the spatial pattern of molecular diversity throughout the range of this species complex, we obtained DNA sequence data from two mitochondrial genes, cytochrome oxidase I (COI) and the 16S rhibosomal gene (16S) for 407 samples of D. minutus and closely related species distributed across eleven countries, effectively comprising the entire range of the group. We performed phylogenetic and spatially explicit phylogeographic analyses to assess the genetic structure of lineages and infer ancestral areas. We found 43 statistically supported, deep mitochondrial lineages, several of which may represent currently unrecognized distinct species. One major clade, containing 25 divergent lineages, includes samples from the type locality of D. minutus. We defined that clade as the D. minutus complex. The remaining lineages together with the D. minutus complex constitute the D. minutus species group. Historical analyses support an Amazonian origin for the D. minutus species group with a subsequent dispersal to eastern Brazil where the D. minutus complex originated. According to our dataset, a total of eight mtDNA lineages have ranges >100,000 km2. One of them occupies an area of almost one million km2 encompassing multiple biomes. Our results, at a spatial scale and resolution unprecedented for a Neotropical vertebrate, confirm that widespread amphibian species occur in lowland South America, yet at the same time a large proportion of cryptic diversity still remains to be discovered

    Recurrent Bacteremia, a Complication of Cyanoacrylate Injection for Variceal Bleeding: Report of Two Cases and Review of the Literature

    Get PDF
    We report the first description of recurrent bacteremia in two patients after cyanoacrylate injection for gastric varices bleeding treated with antibiotics alone. Adapted and prolonged antibiotic treatment allowed a complete resolution of the infection with no relapse after more than 6 months. According to recent data, prophylactic antibiotics should be further investigated for patients with bleeding varices undergoing cyanoacrylate injection

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

    Get PDF
    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

    Asymptomatic neurocognitive disorders in patients infected by HIV: fact or fiction?

    Get PDF
    Neurocognitive disorders are emerging as a possible complication in patients infected with HIV. Even if asymptomatic, neurocognitive abnormalities are frequently detected using a battery of tests. This supported the creation of asymptomatic neurocognitive impairment (ANI) as a new entity. In a recent article published in BMC Infectious Diseases, Magnus Gisslén and colleagues applied a statistical approach, concluding that there is an overestimation of the actual problem. In fact, about 20% of patients are classified as neurocognitively impaired without a clear impact on daily activities. In the present commentary, we discuss the clinical implications of their findings. Although a cautious approach would indicate a stricter follow-up of patients affected by this disorder, it is premature to consider it as a proper disease. Based on a review of the data in the current literature we conclude that it is urgent to conduct more studies to estimate the overall risk of progression of the asymptomatic neurocognitive impairment. Moreover, it is important to understand whether new biomarkers or neuroimaging tools can help to identify better the most at risk population

    Increased Muscle Stress-Sensitivity Induced by Selenoprotein N Inactivation in Mouse: A Mammalian Model for SEPN1-Related Myopathy

    Get PDF
    Selenium is an essential trace element and selenoprotein N (SelN) was the first selenium-containing protein shown to be directly involved in human inherited diseases. Mutations in the SEPN1 gene, encoding SelN, cause a group of muscular disorders characterized by predominant affection of axial muscles. SelN has been shown to participate in calcium and redox homeostasis, but its pathophysiological role in skeletal muscle remains largely unknown. To address SelN function in vivo, we generated a Sepn1-null mouse model by gene targeting. The Sepn1−/− mice had normal growth and lifespan, and were macroscopically indistinguishable from wild-type littermates. Only minor defects were observed in muscle morphology and contractile properties in SelN-deficient mice in basal conditions. However, when subjected to challenging physical exercise and stress conditions (forced swimming test), Sepn1−/− mice developed an obvious phenotype, characterized by limited motility and body rigidity during the swimming session, as well as a progressive curvature of the spine and predominant alteration of paravertebral muscles. This induced phenotype recapitulates the distribution of muscle involvement in patients with SEPN1-Related Myopathy, hence positioning this new animal model as a valuable tool to dissect the role of SelN in muscle function and to characterize the pathophysiological process

    Cognitive and Neurologic Rehabilitation Strategies for Central Nervous System HIV Infection

    Get PDF
    PURPOSE OF REVIEW: Cognitive impairment leading to disability is increasingly seen in people living with human immunodeficiency virus (PLWH). Rehabilitation can alleviate the effects of cognitive impairment upon function. The aim of this paper is to discuss the strategies that have been used in cognitive and neurologic rehabilitation in PLWH. RECENT FINDINGS: Studies examining pharmacological and non-pharmacological strategies were analysed. Medical management of HIV and co-morbidities should be optimised. Non-pharmacological strategies, including nerve stimulation techniques, exercise-based interventions, and paper and computer-based cognitive rehabilitation, have some evidence supporting their use in PLWH either as stand-alone interventions or as part of a multidisciplinary approach. Both pharmacological and non-pharmacological rehabilitation strategies have been used with PLWH. More intervention trials are needed to assess cognitive and neurological rehabilitation strategies and further evaluate their potential benefit in PLWH

    Relaxation of Selective Constraints Causes Independent Selenoprotein Extinction in Insect Genomes

    Get PDF
    BACKGROUND: Selenoproteins are a diverse family of proteins notable for the presence of the 21st amino acid, selenocysteine. Until very recently, all metazoan genomes investigated encoded selenoproteins, and these proteins had therefore been believed to be essential for animal life. Challenging this assumption, recent comparative analyses of insect genomes have revealed that some insect genomes appear to have lost selenoprotein genes. METHODOLOGY/PRINCIPAL FINDINGS: In this paper we investigate in detail the fate of selenoproteins, and that of selenoprotein factors, in all available arthropod genomes. We use a variety of in silico comparative genomics approaches to look for known selenoprotein genes and factors involved in selenoprotein biosynthesis. We have found that five insect species have completely lost the ability to encode selenoproteins and that selenoprotein loss in these species, although so far confined to the Endopterygota infraclass, cannot be attributed to a single evolutionary event, but rather to multiple, independent events. Loss of selenoproteins and selenoprotein factors is usually coupled to the deletion of the entire no-longer functional genomic region, rather than to sequence degradation and consequent pseudogenisation. Such dynamics of gene extinction are consistent with the high rate of genome rearrangements observed in Drosophila. We have also found that, while many selenoprotein factors are concomitantly lost with the selenoproteins, others are present and conserved in all investigated genomes, irrespective of whether they code for selenoproteins or not, suggesting that they are involved in additional, non-selenoprotein related functions. CONCLUSIONS/SIGNIFICANCE: Selenoproteins have been independently lost in several insect species, possibly as a consequence of the relaxation in insects of the selective constraints acting across metazoans to maintain selenoproteins. The dispensability of selenoproteins in insects may be related to the fundamental differences in antioxidant defense between these animals and other metazoans.The work described here is funded by grants from the Spanish Ministery of Education and Science and from the BioSapiens European Network of Excellence to RG. CEC is reciepient of a pre-doctoral fellowship from the Spanish Ministery of Education and Science

    Africa’s response to the COVID-19 pandemic : A review of the nature of the virus, impacts and implications for preparedness

    Get PDF
    Background: COVID-19 continues to wreak havoc in different countries across the world, claiming thousands of lives, increasing morbidity and disrupting lifestyles. The global scientific community is in urgent need of relevant evidence, to understand the challenges and knowledge gaps, as well as the opportunities to contain the spread of the virus. Considering the unique socio-economic, demographic, political, ecological and climatic contexts in Africa, the responses which may prove to be successful in other regions may not be appropriate on the continent. This paper aims to provide insight for scientists, policy makers and international agencies to contain the virus and to mitigate its impact at all levels. Methods: The Affiliates of the African Academy of Sciences (AAS), came together to synthesize the current evidence, identify the challenges and opportunities to enhance the understanding of the disease. We assess the potential impact of this pandemic and the unique challenges of the disease on African nations. We examine the state of Africa’s preparedness and make recommendations for steps needed to win the war against this pandemic and combat potential resurgence. Results: We identified gaps and opportunities among cross-cutting issueswhich must be addressed or harnessed in this pandemic. Factors such as the nature of the virus and the opportunities for drug targeting, point of care diagnostics, health surveillance systems, food security, mental health, xenophobia and gender-based violence, shelter for the homeless, water and sanitation, telecommunications challenges, domestic regional coordination and financing. Conclusion: Based on our synthesis of the current evidence, while there are plans for preparedness in several African countries, there are significant limitations. A multi-sectoral efforts from the science, education, medical, technology, communication, business, and industry sectors, as well as local communities, must work collaboratively to assist countries in order to win this fight
    corecore