341 research outputs found
Evaluation of Immunomodulatory Biomarkers in a Pressure Overload Model of Heart Failure
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90380/1/phco.27.4.504.pd
New ophthalmosaurid ichthyosaurs from the European lower cretaceous demonstrate extensive ichthyosaur survival across the Jurassic–Cretaceous boundary
Background
Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood.
Methodology/Principal Findings
Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval.
Conclusions/Significance
There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous
Exhausted CD4+ T Cells during Malaria Exhibit Reduced mTORc1 Activity Correlated with Loss of T-bet Expression
CD4<sup>+</sup> T cell functional inhibition (exhaustion) is a hallmark of malaria and correlates with impaired parasite control and infection chronicity. However, the mechanisms of CD4<sup>+</sup> T cell exhaustion are still poorly understood. In this study, we show that Ag-experienced (<i>Ag-exp</i>) CD4<sup>+</sup> T cell exhaustion during <i>Plasmodium yoelii</i> nonlethal infection occurs alongside the reduction in mammalian target of rapamycin (mTOR) activity and restriction in CD4<sup>+</sup> T cell glycolytic capacity. We demonstrate that the loss of glycolytic metabolism and mTOR activity within the exhausted <i>Ag-exp</i>CD4<sup>+</sup> T cell population during infection coincides with reduction in T-bet expression. T-bet was found to directly bind to and control the transcription of various mTOR and metabolism-related genes within effector CD4<sup>+</sup> T cells. Consistent with this, <i>Ag-exp</i>Th1 cells exhibited significantly higher and sustained mTOR activity than effector T-bet- (non-Th1) <i>Ag-exp</i>T cells throughout the course of malaria. We identified mTOR to be redundant for sustaining T-bet expression in activated Th1 cells, whereas mTOR was necessary but not sufficient for maintaining IFN-γ production by Th1 cells. Immunotherapy targeting PD-1, CTLA-4, and IL-27 blocked CD4<sup>+</sup> T cell exhaustion during malaria infection and was associated with elevated T-bet expression and a concomitant increased CD4<sup>+</sup> T cell glycolytic metabolism. Collectively, our data suggest that mTOR activity is linked to T-bet in <i>Ag-exp</i>CD4<sup>+</sup> T cells but that reduction in mTOR activity may not directly underpin <i>Ag-exp</i>Th1 cell loss and exhaustion during malaria infection. These data have implications for therapeutic reactivation of exhausted CD4<sup>+</sup> T cells during malaria infection and other chronic conditions
Measurement of the neutrino mass splitting and flavor mixing by MINOS
Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of protons on target. A fit to neutrino oscillations yields values of ,eV for the atmospheric mass splitting and m sin^2!(2 heta) > 0.90 (90%,C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively
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Improved Search for Muon-Neutrino to Electron-Neutrino Oscillations in MINOS
We report the results of a search for ν_e appearance in a ν_μ beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2×10^(20) protons on the NuMI target at Fermilab, we find 2sin^2(θ_(23))sin^2(2θ_(13))<0.12(0.20) at 90% confidence
level for δ=0 and the normal (inverted) neutrino mass hierarchy, with a best-fit of 2sin^2(θ_(23))sin^2(2θ_(13))=0.041^(+0.047)_(-0.031)(0.079^(+0.071)_(-0.053).
The θ_(13)= 0 hypothesis is disfavored by the MINOS data
at the 89% confidence level
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Measurement of the underground atmospheric muon charge ratio using the MINOS Near Detector
The magnetized MINOS Near Detector, at a depth of 225 mwe, is used to measure the atmospheric muon charge ratio. The ratio of observed positive to negative atmospheric muon rates, using 301 days of data, is measured to be 1.266±0.001(stat)_(-0.014)^(+0.015)(syst). This measurement is consistent with previous results from other shallow underground detectors and is 0.108±0.019(stat+syst) lower than the measurement at the functionally identical MINOS Far Detector at a depth of 2070 mwe. This increase in charge ratio as a function of depth is consistent with an increase in the fraction of muons arising from kaon decay for increasing muon surface energie
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Measurement of the Neutrino Mass Splitting and Flavor Mixing by MINOS
Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of 7.25×10^(20) protons on target. A fit to neutrino oscillations yields values of |Δm^2|=(2.32_(-0.08)^(+0.12))×10^(-3)  eV^2 for the atmospheric mass splitting and sin^2(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively
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New constraints on muon-neutrino to electron-neutrino transitions in MINOS
This paper reports results from a search for ν_μ → ν_e transitions by the MINOS experiment based on a 7×10^(20) protons-on-target exposure. Our observation of 54 candidate ν_e events in the far detector with a background of 49.1±7.0(stat)±2.7(syst) events predicted by the measurements in the near detector requires 2sin^2(2θ_(13))sin^2θ_(23)<0.12(0.20) at the 90% C.L. for the normal (inverted) mass hierarchy at δ_(CP)=0. The experiment sets the tightest limits to date on the value of θ_(13) for nearly all values of δ_(CP) for the normal neutrino mass hierarchy and maximal sin^2(2θ_(23))
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