296 research outputs found

    Memory is relevant in the symmetric phase of the minority game

    Get PDF
    Minority game is a simple-mined econophysical model capturing the cooperative behavior among selfish players. Previous investigations, which were based on numerical simulations up to about 100 players for a certain parameter Î in the range 0.1â‰Îâ‰1, suggested that memory is irrelevant to the cooperative behavior of the minority game in the so-called symmetric phase. Here using a large scale numerical simulation up to about 3000 players in the parameter range 0. 01â‰Îâ‰1, we show that the mean variance of the attendance in the minority game actually depends on the memory in the symmetric phase. We explain such dependence in the framework of crowd-anticrowd theory. Our findings conclude that one should not overlook the feedback mechanism buried under the correlation in the history time series in the study of minority game. © 2005 The American Physical Society.published_or_final_versio

    Esrrb Complementation Rescues Development of Nanog-Null Germ Cells.

    Get PDF
    The transcription factors (TFs) Nanog and Esrrb play important roles in embryonic stem cells (ESCs) and during primordial germ-cell (PGC) development. Esrrb is a positively regulated direct target of NANOG in ESCs that can substitute qualitatively for Nanog function in ESCs. Whether this functional substitution extends to the germline is unknown. Here, we show that germline deletion of Nanog reduces PGC numbers 5-fold at midgestation. Despite this quantitative depletion, Nanog-null PGCs can complete germline development in contrast to previous findings. PGC-like cell (PGCLC) differentiation of Nanog-null ESCs is also impaired, with Nanog-null PGCLCs showing decreased proliferation and increased apoptosis. However, induced expression of Esrrb restores PGCLC numbers as efficiently as Nanog. These effects are recapitulated in vivo: knockin of Esrrb to Nanog restores PGC numbers to wild-type levels and results in fertile adult mice. These findings demonstrate that Esrrb can replace Nanog function in germ cells

    Association of maternal levothyroxine use during pregnancy with offspring birth and neurodevelopmental outcomes: a population-based cohort study

    Get PDF
    BACKGROUND: The influence of maternal levothyroxine treatment during pregnancy remains unclear. This study aimed to evaluate the associations of maternal levothyroxine treatment during pregnancy with the birth and neurodevelopmental outcomes in offspring. METHODS: This population-based cohort study was conducted among pregnant women using the Hong Kong Clinical Data Analysis and Reporting System. Mother-child pairs in Hong Kong from 2001 to 2015 were included and children were followed up till 2020. We defined the exposure group as mothers who were exposed to levothyroxine during pregnancy. Preterm birth and small for gestational age (SGA) were included as birth outcomes. Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) were included as neurodevelopmental outcomes. Odds ratios (OR) or hazard ratios (HRs) with a 95% confidence interval (CI) were evaluated to assess the association of gestational levothyroxine use with offspring birth and neurodevelopmental outcomes respectively, using propensity score fine-stratification weighting and a Cox proportional hazards regression model. RESULTS: Among 422,156 mother-child pairs, 2125 children were born from mothers exposed to levothyroxine during pregnancy. A significantly increased risk of preterm birth was observed in children with maternal levothyroxine exposure during pregnancy, when compared to mothers who had no history of thyroid-related diagnoses or prescriptions (weighted OR [wOR]: 1.22, 95% CI: 1.07, 1.39). Similarly, an increased risk of preterm birth was found among children of gestational levothyroxine users, when compared to children of mothers who had used levothyroxine before but stopped during pregnancy (wOR: 2.16, 95% CI: 1.09, 4.25). Sensitivity analysis, by excluding mothers exposed to psychotropic or antiepileptic medications before or during pregnancy, also indicated a similar increased risk of preterm birth regarding the gestational use of levothyroxine (wOR: 1.26, 95% CI: 1.10, 1.45). No significant association was observed for the risk of SGA, ADHD, and ASD. CONCLUSIONS: There is no evidence that gestational use of levothyroxine is associated with SGA, ADHD, or ASD in offspring. Gestational levothyroxine treatment is associated with a higher risk of preterm birth. Such risk might be confounded by the underlying maternal thyroid disease itself, however, we cannot completely exclude the possible effect of gestational L-T4 treatment on offspring preterm birth. Our findings provided support to the current guidelines on the cautious use of levothyroxine treatment during pregnancy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12916-022-02586-9

    Molecular dissection of the interplay between SIRT1, LKB1 and HERC2: linkage implication in endothelial senescence and vascular remodeling

    Get PDF
    Symposium Theme: From Molecular Machinery to Clinical ChallengesPoster Session 3: Late Breaking Abstracts & Vendor Exhibits: no. PS3-4: abstract ISRA156Endothelial senescence is one of the earliest events during vascular aging and contributes to vascular remodeling. Sirtuin-1 (SIRT1) elicits its anti-senescent functions in part by mediating proteasome-mediated degradation of LKB1, a pro-senescent protein kinase [1], [2]. The present study was designed to investigate the molecular mechanisms underlying SIRT1-regulated LKB1 degradation by focusing on an E3 ligase, HERC2 (HECT domain and RLD 2 protein). In primary porcine aortic endothelial cells (PAECs), LKB1 degradation was significantly blocked by MG132. Western blotting revealed that LKB1 was ubiquitinated and degraded in nucleus. HERC2 was identified as the E3 ligase of LKB1. Knockdown of HERC2 enhanced the protein accumulation of LKB1 in nucleus and promoted ...postprin

    Matrix metalloproteinase-9 activity and a downregulated Hedgehog pathway impair blood-brain barrier function in an <i>in vitro</i> model of CNS tuberculosis

    Get PDF
    Central nervous system tuberculosis (CNS TB) has a high mortality and morbidity associated with severe inflammation. The blood-brain barrier (BBB) protects the brain from inflammation but the mechanisms causing BBB damage in CNS TB are uncharacterized. We demonstrate that Mycobacterium tuberculosis (Mtb) causes breakdown of type IV collagen and decreases tight junction protein (TJP) expression in a co-culture model of the BBB. This increases permeability, surface expression of endothelial adhesion molecules and leukocyte transmigration. TJP breakdown was driven by Mtb-dependent secretion of matrix metalloproteinase (MMP)-9. TJP expression is regulated by Sonic hedgehog (Shh) through transcription factor Gli-1. In our model, the hedgehog pathway was downregulated by Mtb-stimulation, but Shh levels in astrocytes were unchanged. However, Scube2, a glycoprotein regulating astrocyte Shh release was decreased, inhibiting Shh delivery to brain endothelial cells. Activation of the hedgehog pathway by addition of a Smoothened agonist or by addition of exogenous Shh, or neutralizing MMP-9 activity, decreased permeability and increased TJP expression in the Mtb-stimulated BBB co-cultures. In summary, the BBB is disrupted by downregulation of the Shh pathway and breakdown of TJPs, secondary to increased MMP-9 activity which suggests that these pathways are potential novel targets for host directed therapy in CNS TB

    The Main Belt Comets and ice in the Solar System

    Get PDF
    We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies

    The effect of glucocorticoids on tendon cell viability in human tendon explants

    Get PDF
    Background and purpose Previous studies on the culture of human tenocytes have shown that dexamethasone and triamcino-lone reduce cell viability, suppress cell proliferation, and reduce collagen synthesis. However, such cell cultures lack the extracellular matrix and three-dimensional structure of normal tendons, which affects their response to stimuli. We established a human tendon explant culture system and tested the effects of dexamethasone and triamcinolone on cell viability

    Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

    Get PDF
    We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

    Brain Deletion of Insulin Receptor Substrate 2 Disrupts Hippocampal Synaptic Plasticity and Metaplasticity

    Get PDF
    Diabetes mellitus is associated with cognitive deficits and an increased risk of dementia, particularly in the elderly. These deficits and the corresponding neurophysiological structural and functional alterations are linked to both metabolic and vascular changes, related to chronic hyperglycaemia, but probably also defects in insulin action in the brain. To elucidate the specific role of brain insulin signalling in neuronal functions that are relevant for cognitive processes we have investigated the behaviour of neurons and synaptic plasticity in the hippocampus of mice lacking the insulin receptor substrate protein 2 (IRS-2)
    corecore