1,391 research outputs found
Increased vascular contractility in hypertension results from impaired endothelial calcium signaling
Endothelial cells line all blood vessels and are critical regulators of vascular tone. In hypertension, disruption of endothelial function alters the release of endothelial-derived vasoactive factors and results in increased vascular tone. Although the release of endothelial-derived vasodilators occurs in a Ca2+-dependent manner, little is known on how Ca2+ signaling is altered in hypertension. A key element to endothelial control of vascular tone is Ca2+ signals at specialized regions (myoendothelial projections) that connect endothelial cells and smooth muscle cells. This work describes disruption in the operation of this key Ca2+ signaling pathway in hypertension. We show that vascular reactivity to phenylephrine is increased in hypertensive (spontaneously hypertensive rat) when compared with normotensive (Wistar Kyoto) rats. Basal endothelial Ca2+ activity limits vascular contraction, but that Ca2+-dependent control is impaired in hypertension. When changes in endothelial Ca2+ levels are buffered, vascular contraction to phenylephrine increased, resulting in similar responses in normotension and hypertension. Local endothelial IP3(inositol trisphosphate)-mediated Ca2+ signals are smaller in amplitude, shorter in duration, occur less frequently, and arise from fewer sites in hypertension. Spatial control of endothelial Ca2+ signaling is also disrupted in hypertension: local Ca2+ signals occur further from myoendothelial projections in hypertension. The results demonstrate that the organization of local Ca2+ signaling circuits occurring at myoendothelial projections is disrupted in hypertension, giving rise to increased contractile responses
Safety and efficacy of anti-tau monoclonal antibody gosuranemab in progressive supranuclear palsy: a phase 2, randomized, placebo-controlled trial
A randomized, double-blind, placebo-controlled, 52-week study (no. NCT03068468) evaluated gosuranemab, an anti-tau monoclonal antibody, in the treatment of progressive supranuclear palsy (PSP). In total, 486âparticipants dosed were assigned to either gosuranemab (nâ=â321) or placebo (nâ=â165). Efficacy was not demonstrated on adjusted mean change of PSP Rating Scale score at weekâ52 between gosuranemab and placebo (10.4 versus 10.6, Pâ=â0.85, primary endpoint), or at secondary endpoints, resulting in discontinuation of the open-label, long-term extension. Unbound N-terminal tau in cerebrospinal fluid decreased by 98% with gosuranemab and increased by 11% with placebo (Pâ<â0.0001). Incidences of adverse events and deaths were similar between groups. This well-powered study suggests that N-terminal tau neutralization does not translate into clinical efficacy
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Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments.
Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{Îźe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Îm_{41}^{2}, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL_{s} for Îm_{41}^{2}<13ââeV^{2}. Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL_{s} for Îm_{41}^{2}<1.6âeV^{2}
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First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA.
The NOvA experiment has seen a 4.4Ď signal of ν[over ÂŻ]_{e} appearance in a 2 GeV ν[over ÂŻ]_{Îź} beam at a distance of 810 km. Using 12.33Ă10^{20} protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν[over ÂŻ]_{Îź}âν[over ÂŻ]_{e} candidates with a background of 10.3 and 102 ν[over ÂŻ]_{Îź}âν[over ÂŻ]_{Îź} candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Îm_{32}^{2}|=2.48_{-0.06}^{+0.11}Ă10^{-3}ââeV^{2}/c^{4} and sin^{2}θ_{23} in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δ_{CP}=Ď/2 for the inverted mass hierarchy by more than 3Ď and favor the normal neutrino mass hierarchy by 1.9Ď and θ_{23} values in the upper octant by 1.6Ď
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Observation of seasonal variation of atmospheric multiple-muon events in the NOvA Near Detector
Using two years of data from the NOvA Near Detector at Fermilab, we report a seasonal variation of cosmic ray induced multiple-muon (NÎźâĽ2) event rates which has an opposite phase to the seasonal variation in the atmospheric temperature. The strength of the seasonal multiple-muon variation is shown to increase as a function of the muon multiplicity. However, no significant dependence of the strength of the seasonal variation of the multiple-muon variation is seen as a function of the muon zenith angle, or the spatial or angular separation between the correlated muons
The Signaller's Dilemma: A CostâBenefit Analysis of Public and Private Communication
Understanding the diversity of animal signals requires knowledge of factors which may influence the different stages of communication, from the production of a signal by the sender up to the detection, identification and final decision-making in the receiver. Yet, many studies on signalling systems focus exclusively on the sender, and often ignore the receiver side and the ecological conditions under which signals evolve.We study a neotropical katydid which uses airborne sound for long distance communication, but also an alternative form of private signalling through substrate vibration. We quantified the strength of predation by bats which eavesdrop on the airborne sound signal, by analysing insect remains at roosts of a bat family. Males do not arbitrarily use one or the other channel for communication, but spend more time with private signalling under full moon conditions, when the nocturnal rainforest favours predation by visually hunting predators. Measurements of metabolic CO(2)-production rate indicate that the energy necessary for signalling increases 3-fold in full moon nights when private signalling is favoured. The background noise level for the airborne sound channel can amount to 70 dB SPL, whereas it is low in the vibration channel in the low frequency range of the vibration signal. The active space of the airborne sound signal varies between 22 and 35 meters, contrasting with about 4 meters with the vibration signal transmitted on the insect's favourite roost plant. Signal perception was studied using neurophysiological methods under outdoor conditions, which is more reliable for the private mode of communication.Our results demonstrate the complex effects of ecological conditions, such as predation, nocturnal ambient light levels, and masking noise levels on the performance of receivers in detecting mating signals, and that the net advantage or disadvantage of a mode of communication strongly depends on these conditions
Search for sterile neutrino mixing in the MINOS long-baseline experiment
A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18Ă1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿¾, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿¾ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles Âż24 and Âż34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1Ă10-12¿¿s/eV at 90% C.L
Quantification of the relative contribution of the different right ventricular wall motion components to right ventricular ejection fraction
Abstract Three major mechanisms contribute to right ventricular (RV) pump function: (i) shortening of the longitudinal axis with traction of the tricuspid annulus towards the apex; (ii) inward movement of the RV free wall; (iii) bulging of the interventricular septum into the RV and stretching the free wall over the septum. The relative contribution of the aforementioned mechanisms to RV pump function may change in different pathological conditions. Our aim was to develop a custom method to separately assess the extent of longitudinal, radial and anteroposterior displacement of the RV walls and to quantify their relative contribution to global RV ejection fraction using 3D data sets obtained by echocardiography. Accordingly, we decomposed the movement of the exported RV beutel wall in a vertex based manner. The volumes of the beutels accounting for the RV wall motion in only one direction (either longitudinal, radial, or anteroposterior) were calculated at each time frame using the signed tetrahedron method. Then, the relative contribution of the RV wall motion along the three different directions to global RV ejection fraction was calculated either as the ratio of the given directionâs ejection fraction to global ejection fraction and as the frame-by-frame RV volume change (âV/ât) along the three motion directions. The ReVISION (Right VentrIcular Separate wall motIon quantificatiON) method may contribute to a better understanding of the pathophysiology of RV mechanical adaptations to different loading conditions and diseases
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