Publications by authors named "Varin C"

The dorsal striatum is instrumental in regulating motor control and goal-directed behaviors. The classical description of the two output pathways of the dorsal striatum highlights their antagonistic control over actions. However, recent experimental evidence implicates both pathways and their coordinated activities during actions.

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Bromine in ice cores has been proposed as a qualitative sea ice proxy to produce sea ice reconstructions for the polar regions. Here we report the first statistical validation of this proxy with satellite sea ice observations by combining bromine enrichment (with respect to seawater, Br) records from three Greenlandic ice cores (SIGMA-A, NU and RECAP) with satellite sea ice imagery, over three decades. We find that during the 1984-2016 satellite-era, ice core Br values are significantly correlated with first-year sea ice formed in the Baffin Bay and Labrador Sea supporting that the gas-phase bromine enrichment processes, preferentially occurring over the sea ice surface, are the main driver for the Br signal in ice cores.

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The role of the striatum in motor control is commonly assumed to be mediated by the two striatal efferent pathways characterized by striatal projection neurons (SPNs) expressing dopamine (DA) D1 receptors or D2 receptors (D1-SPNs and D2-SPNs, respectively), without regard to SPNs coexpressing both receptors (D1/D2-SPNs). Here we developed an approach to target these hybrid SPNs in mice and demonstrate that, although these SPNs are less abundant, they have a major role in guiding the motor function of the other two populations. D1/D2-SPNs project exclusively to the external globus pallidus and have specific electrophysiological features with distinctive integration of DA signals.

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Accumulating evidence points to dysregulations of the Nucleus Accumbens (NAc) in eating disorders (ED), however its precise contribution to ED symptomatic dimensions remains unclear. Using chemogenetic manipulations in male mice, we found that activity of dopamine D1 receptor-expressing neurons of the NAc core subregion facilitated effort for a food reward as well as voluntary exercise, but decreased food intake, while D2-expressing neurons have opposite effects. These effects are congruent with D2-neurons being more active than D1-neurons during feeding while it is the opposite during running.

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The basal ganglia are known to control actions and modulate movements. Neuronal activity in the two efferent pathways of the dorsal striatum is critical for appropriate behavioral control. Previous evidence has led to divergent conclusions on the respective engagement of both pathways during actions.

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Sea ice decline in the North Atlantic and Nordic Seas has been proposed to contribute to the repeated abrupt atmospheric warmings recorded in Greenland ice cores during the last glacial period, known as Dansgaard-Oeschger (D-O) events. However, the understanding of how sea ice changes were coupled with abrupt climate changes during D-O events has remained incomplete due to a lack of suitable high-resolution sea ice proxy records from northwestern North Atlantic regions. Here, we present a subdecadal-scale bromine enrichment (Br) record from the NEEM ice core (Northwest Greenland) and sediment core biomarker records to reconstruct the variability of seasonal sea ice in the Baffin Bay and Labrador Sea over a suite of D-O events between 34 and 42 ka.

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Background: The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown.

Methods: We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.

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Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is being tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC-HF) trial. Here we describe the baseline characteristics of participants in GALACTIC-HF and how these compare with other contemporary trials.

Methods And Results: Adults with established HFrEF, New York Heart Association (NYHA) functional class ≥II, ejection fraction ≤35%, elevated natriuretic peptides and either current hospitalization for heart failure or history of hospitalization/emergency department visit for heart failure within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic-guided dosing: 25, 37.

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Nearly all ice core archives from the Arctic and middle latitudes (such as the Alps), apart from some very high elevation sites in Greenland and the North Pacific, are strongly influenced by melting processes. The increases in the average Arctic temperature has enhanced surface snow melting even of higher elevation ice caps, especially on the Svalbard Archipelago. The increase of the frequency and altitude of winter "rain on snow" events as well as the increase of the length of the melting season have had a direct impact on the chemical composition of the seasonal and permanent snow layers due to different migration processes of water-soluble species, such as inorganic ions.

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Background: The usefulness of adjudication by central end point committees (CECs) is poorly assessed in heart failure (HF) trials. We aimed to assess its impact on the outcome of the SHIFT trial (Systolic HF Treatment With the If Inhibitor Ivabradine Trial).

Methods: SHIFT was a randomized placebo-controlled trial investigating the effect of ivabradine in 6505 HF patients with reduced ejection fraction.

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Latent autoregressive models are useful time series models for the analysis of infectious disease data. Evaluation of the likelihood function of latent autoregressive models is intractable and its approximation through simulation-based methods appears as a standard practice. Although simulation methods may make the inferential problem feasible, they are often computationally intensive and the quality of the numerical approximation may be difficult to assess.

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A central factor in the pathogenesis of heart failure (HF) with reduced ejection fraction is the initial decrease in systolic function. Prior attempts at increasing cardiac contractility with oral drugs have uniformly resulted in signals of increased mortality at pharmacologically effective doses. Omecamtiv mecarbil is a novel, selective cardiac myosin activator that has been shown to improve cardiac function and to decrease ventricular volumes, heart rate, and N-terminal pro-B-type natriuretic peptide in patients with chronic HF.

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Study Objectives: The regulation of sleep-wake cycles is crucial for the brain's health and cognitive skills. Among the various substances known to control behavioral states, intraventricular injection of neuropeptide S (NPS) has already been shown to promote wakefulness. However, the NPS signaling pathway remains elusive.

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Over the past decade, basic sleep research investigating the circuitry controlling sleep and wakefulness has been boosted by pharmacosynthetic approaches, including chemogenetic techniques using designed receptors exclusively activated by designer drugs (DREADD). DREADD offers a series of tools that selectively control neuronal activity as a way to probe causal relationship between neuronal sub-populations and the regulation of the sleep-wake cycle. Following the path opened by optogenetics, DREADD tools applied to discrete neuronal sub-populations in numerous brain areas quickly made their contribution to the discovery and the expansion of our understanding of critical brain structures involved in a wide variety of behaviors and in the control of vigilance state architecture.

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The striatum as the main entry nucleus of the basal ganglia is long known to be critical for motor control. It integrates information from multiple cortical areas, thalamic and midbrain nuclei to refine and control motion. By tackling this incredible variety of input signals, increasing evidences showed a pivotal role, particularly of the dorsal striatum, in executive functions.

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We evaluated differences in density and F-FDG PET/MRI features of lytic bone lesions (LBLs) identified by whole-body low-dose CT (WB-LDCT) in patients affected by newly diagnosed multiple myeloma (MM). In 18 MM patients, 135 unequivocal LBLs identified by WB-LDCT were characterized for inner density (negative or positive Hounsfield unit (HU)), where negative density (HU < 0) characterizes normal yellow marrow whereas positive HU correlates with tissue-like infiltrative pattern. The same LBLs were analyzed by F-FDG PET/DWI-MRI, registering DWI signal with ADC and SUV max values.

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Study Objectives: Experimental studies over the last 15 years established a role in sleep of the tuberal hypothalamic neurons that express melanin-concentrating hormone (MCH). Controversies still remain regarding their actual contribution to both slow-wave sleep (SWS) and paradoxical sleep (PS also known as REM sleep) or PS alone.

Methods: To address this point, we compared effects of chemogenetic activation and inhibition of MCH neurons on SWS and PS amounts and EEG rhythmic activities in transgenic Pmch-cre mice.

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Whereas the Kerr nonlinearity is well understood in the perturbative limit of nonlinear optics, there is considerable discussion about its functional form and magnitude at extreme intensities, at which point matter starts to ionize. Here, we introduce a concept to answer this question and theoretically analyze its feasibility. We demonstrate that seeded Kerr instability amplification provides clear signatures from which functional form and magnitude of the Kerr nonlinearity can be extracted in the non-perturbative limit of nonlinear optics.

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The Antarctic Plateau snowpack is an important environment for the mercury geochemical cycle. We have extensively characterized and compared the changes in surface snow and atmospheric mercury concentrations that occur at Dome C. Three summer sampling campaigns were conducted between 2013 and 2016.

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Aim: To evaluate the modifications of the apparent diffusion coefficient (ADC) in myelomatous lesions before and after induction treatment and the correlation with patient response to therapy according to International Myeloma Working Group (IMWG) criteria.

Materials And Methods: A homogeneous group of 18 patients with a diagnosis of symptomatic multiple myeloma who underwent whole-body MRI with diffusion-weighted imaging (DWI-MRI) before and after bortezomib-based induction chemotherapy were evaluated prospectively. Quantitative analysis of ADC maps of myelomatous lesions was performed with the following pattern types: focal pattern, diffuse pattern (moderate and severe), and "salt and pepper" pattern.

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Regulatory authorities interpret the results of randomized controlled trials according to published principles. The European Medicines Agency (EMA) is planning a revision of the 2000 and 2003 guidance documents on clinical investigation of new medicinal products for the treatment of acute coronary syndrome (ACS) to achieve consistency with current knowledge in the field. This manuscript summarizes the key output from a collaborative workshop, organized by the Cardiovascular Round Table and the European Affairs Committee of the European Society of Cardiology, involving clinicians, academic researchers, trialists, European and US regulators, and pharmaceutical industry researchers.

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Rankings of scholarly journals based on citation data are often met with scepticism by the scientific community. Part of the scepticism is due to disparity between the common perception of journals' prestige and their ranking based on citation counts. A more serious concern is the inappropriate use of journal rankings to evaluate the scientific influence of researchers.

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Recent reports support a key role of tuberal hypothalamic neurons secreting melanin concentrating-hormone (MCH) in the promotion of Paradoxical Sleep (PS). Controversies remain concerning their concomitant involvement in Slow-Wave Sleep (SWS). We studied the effects of their selective loss achieved by an Ataxin 3-mediated ablation strategy to decipher the contribution of MCH neurons to SWS and/or PS.

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Unlabelled: Sleep-active neurons located in the ventrolateral preoptic nucleus (VLPO) play a crucial role in the induction and maintenance of slow-wave sleep (SWS). However, the cellular and molecular mechanisms responsible for their activation at sleep onset remain poorly understood. Here, we test the hypothesis that a rise in extracellular glucose concentration in the VLPO can promote sleep by increasing the activity of sleep-promoting VLPO neurons.

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This paper investigates the impact of the number of studies on meta-analysis and meta-regression within the random-effects model framework. It is frequently neglected that inference in random-effects models requires a substantial number of studies included in meta-analysis to guarantee reliable conclusions. Several authors warn about the risk of inaccurate results of the traditional DerSimonian and Laird approach especially in the common case of meta-analysis involving a limited number of studies.

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