1,965 research outputs found

    Global behavior of cosmological dynamics with interacting Veneziano ghost

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    In this paper, we shall study the dynamical behavior of the universe accelerated by the so called Veneziano ghost dark energy component locally and globally by using the linearization and nullcline method developed in this paper. The energy density is generalized to be proportional to the Hawking temperature defined on the trapping horizon instead of Hubble horizon of the Friedmann-Robertson-Walker (FRW) universe. We also give a prediction of the fate of the universe and present the bifurcation phenomenon of the dynamical system of the universe. It seems that the universe could be dominated by dark energy at present in some region of the parameter space.Comment: 8 pages, 7 figures, accepted for publication in JHE

    Deficiency of vitamins C and E in women of childbearing age in Brazil: a systematic review and meta-analysis

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    Background: Despite current policies of salt iodination, iodine deficiency is still a global public health problem, especially in women. So far, conflicting evidence has been suggested for the prevalence of iodine deficiency in Brazil. Objective: To estimate the prevalence of iodine deficiency and associated factors in women of childbearing age in Brazil. Methods: A systematic review was conducted using databases (PubMed, LILACS, WHO, Scopus, and Capes dissertation and thesis), from inception to May 2020. Meta-analyses of proportions were performed using the variance inverse for the fixed model. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool to prevalence studies. Results: Our review identified seven studies published between 2002 e 2017, including 1354 participants, especially pregnant women. All studies presented at least one quality limitation, mainly regarding the sampling method (i.e., convenience) and small sample size. The prevalence of iodine deficiency ranged among studies from 16% to 62%. In contrast, the meta-analysis identified a mean prevalence of 40% (95% confidence interval, CI 37%-43%) for pregnant women and 13% (95% CI 4%-24%) for non-pregnant women. Cumulative meta-analysis suggests a tendency of higher iodine deficiency prevalence from 2018 in pregnant women. Conclusions: Although this systematic review identified studies with poor methodological and reporting quality, a high prevalence of iodine deficiency was identified in pregnant women, reinforcing the importance of national nutritional policies for monitoring iodine status in this population. Future studies should consider random probabilistic sampling, appropriate sample size, and pre-defined subgroup analysis to adequately inform the prevalence of iodine deficiency and associated factors in women of childbearing age and support health policies

    Iodine deficiency in women of childbearing age in Brazil: systematic review and meta-analysis

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    Background: Despite current policies of salt iodination, iodine deficiency is still a global public health problem, especially in women. So far, conflicting evidence has been suggested for the prevalence of iodine deficiency in Brazil. Objective: To estimate the prevalence of iodine deficiency and associated factors in women of childbearing age in Brazil. Methods: A systematic review was conducted using databases (PubMed, LILACS, WHO, Scopus, and Capes dissertation and thesis), from inception to May 2020. Meta-analyses of proportions were performed using the variance inverse for the fixed model. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool to prevalence studies. Results: Our review identified seven studies published between 2002 e 2017, including 1354 participants, especially pregnant women. All studies presented at least one quality limitation, mainly regarding the sampling method (i.e., convenience) and small sample size. The prevalence of iodine deficiency ranged among studies from 16% to 62%. In contrast, the meta-analysis identified a mean prevalence of 40% (95% confidence interval, CI 37%-43%) for pregnant women and 13% (95% CI 4%-24%) for non-pregnant women. Cumulative meta-analysis suggests a tendency of higher iodine deficiency prevalence from 2018 in pregnant women. Conclusions: Although this systematic review identified studies with poor methodological and reporting quality, a high prevalence of iodine deficiency was identified in pregnant women, reinforcing the importance of national nutritional policies for monitoring iodine status in this population. Future studies should consider random probabilistic sampling, appropriate sample size, and pre-defined subgroup analysis to adequately inform the prevalence of iodine deficiency and associated factors in women of childbearing age and support health policies.</jats:p

    The innate immune sensor Toll-like receptor 2 controls the senescence-associated secretory phenotype

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    Cellular senescence is a stress response program characterized by a robust cell cycle arrest and the induction of a proinflammatory senescence-associated secretory phenotype (SASP) that is triggered through an unknown mechanism. Here, we show that, during oncogene-induced senescence (OIS), the Toll-like receptor 2 (TLR2) and its partner TLR10 are key mediators of senescence in vitro and in murine models. TLR2 promotes cell cycle arrest by regulating the tumor suppressors p53-p21 , p16 , and p15 and regulates the SASP through the induction of the acute-phase serum amyloids A1 and A2 (A-SAAs) that, in turn, function as the damage-associated molecular patterns (DAMPs) signaling through TLR2 in OIS. Last, we found evidence that the cGAS-STING cytosolic DNA sensing pathway primes TLR2 and A-SAAs expression in OIS. In summary, we report that innate immune sensing of senescence-associated DAMPs by TLR2 controls the SASP and reinforces the cell cycle arrest program in OIS

    An algorithm for efficient constrained mate selection

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    <p>Abstract</p> <p>Background</p> <p>Mate selection can be used as a framework to balance key technical, cost and logistical issues while implementing a breeding program at a tactical level. The resulting mating lists accommodate optimal contributions of parents to future generations, in conjunction with other factors such as progeny inbreeding, connection between herds, use of reproductive technologies, management of the genetic distribution of nominated traits, and management of allele/genotype frequencies for nominated QTL/markers.</p> <p>Methods</p> <p>This paper describes a mate selection algorithm that is widely used and presents an extension that makes it possible to apply constraints on certain matings, as dictated through a group mating permission matrix.</p> <p>Results</p> <p>This full algorithm leads to simpler applications, and to computing speed for the scenario tested, which is several hundred times faster than the previous strategy of penalising solutions that break constraints.</p> <p>Conclusions</p> <p>The much higher speed of the method presented here extends the use of mate selection and enables implementation in relatively large programs across breeding units.</p

    Simple, Fast and Accurate Implementation of the Diffusion Approximation Algorithm for Stochastic Ion Channels with Multiple States

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    The phenomena that emerge from the interaction of the stochastic opening and closing of ion channels (channel noise) with the non-linear neural dynamics are essential to our understanding of the operation of the nervous system. The effects that channel noise can have on neural dynamics are generally studied using numerical simulations of stochastic models. Algorithms based on discrete Markov Chains (MC) seem to be the most reliable and trustworthy, but even optimized algorithms come with a non-negligible computational cost. Diffusion Approximation (DA) methods use Stochastic Differential Equations (SDE) to approximate the behavior of a number of MCs, considerably speeding up simulation times. However, model comparisons have suggested that DA methods did not lead to the same results as in MC modeling in terms of channel noise statistics and effects on excitability. Recently, it was shown that the difference arose because MCs were modeled with coupled activation subunits, while the DA was modeled using uncoupled activation subunits. Implementations of DA with coupled subunits, in the context of a specific kinetic scheme, yielded similar results to MC. However, it remained unclear how to generalize these implementations to different kinetic schemes, or whether they were faster than MC algorithms. Additionally, a steady state approximation was used for the stochastic terms, which, as we show here, can introduce significant inaccuracies. We derived the SDE explicitly for any given ion channel kinetic scheme. The resulting generic equations were surprisingly simple and interpretable - allowing an easy and efficient DA implementation. The algorithm was tested in a voltage clamp simulation and in two different current clamp simulations, yielding the same results as MC modeling. Also, the simulation efficiency of this DA method demonstrated considerable superiority over MC methods.Comment: 32 text pages, 10 figures, 1 supplementary text + figur

    Effects of chirality on the intracellular localization of binuclear ruthenium(II) polypyridyl complexes

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    Interest in binuclear ruthenium(II) polypyridyl complexes as luminescent cellular imaging agents and for biomedical applications is increasing rapidly. We have investigated the cellular localization, uptake, and biomolecular interactions of the pure enantiomers of two structural isomers of [μ-bipb(phen)4Ru2]4+ (bipb is bis(imidazo[4,5-f]-1,10-phenanthrolin-2-yl)benzene and phen is 1,10-phenanthroline) using confocal laser scanning microscopy, emission spectroscopy, and linear dichroism. Both complexes display distinct enantiomeric differences in the staining pattern of fixed cells, which are concluded to arise from chiral discrimination in the binding to intracellular components. Uptake of complexes in live cells is efficient and nontoxic at 5 μM, and occurs through an energy-dependent mechanism. No differences in uptake are observed between the structural isomers or the enantiomers, suggesting that the interactions triggering uptake are rather insensitive to structural variations. Altogether, these findings show that the complexes investigated are promising for future applications as cellular imaging probes. In addition, linear dichroism shows that the complexes exhibit DNA-condensing properties, making them interesting as potential gene delivery vectors

    Primary skin fibroblasts as a model of Parkinson's disease

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    Parkinson's disease is the second most frequent neurodegenerative disorder. While most cases occur sporadic mutations in a growing number of genes including Parkin (PARK2) and PINK1 (PARK6) have been associated with the disease. Different animal models and cell models like patient skin fibroblasts and recombinant cell lines can be used as model systems for Parkinson's disease. Skin fibroblasts present a system with defined mutations and the cumulative cellular damage of the patients. PINK1 and Parkin genes show relevant expression levels in human fibroblasts and since both genes participate in stress response pathways, we believe fibroblasts advantageous in order to assess, e.g. the effect of stressors. Furthermore, since a bioenergetic deficit underlies early stage Parkinson's disease, while atrophy underlies later stages, the use of primary cells seems preferable over the use of tumor cell lines. The new option to use fibroblast-derived induced pluripotent stem cells redifferentiated into dopaminergic neurons is an additional benefit. However, the use of fibroblast has also some drawbacks. We have investigated PARK6 fibroblasts and they mirror closely the respiratory alterations, the expression profiles, the mitochondrial dynamics pathology and the vulnerability to proteasomal stress that has been documented in other model systems. Fibroblasts from patients with PARK2, PARK6, idiopathic Parkinson's disease, Alzheimer's disease, and spinocerebellar ataxia type 2 demonstrated a distinct and unique mRNA expression pattern of key genes in neurodegeneration. Thus, primary skin fibroblasts are a useful Parkinson's disease model, able to serve as a complement to animal mutants, transformed cell lines and patient tissues
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