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17
result(s) for
"Quirion, Pierre-Olivier"
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Mutations associated with neuropsychiatric conditions delineate functional brain connectivity dimensions contributing to autism and schizophrenia
by
Moreau, Clara A.
,
Labbe, Aurélie
,
Potvin, Stephane
in
60 APPLIED LIFE SCIENCES
,
631/208/366/1373
,
631/378/1689/1373
2020
16p11.2 and 22q11.2 Copy Number Variants (CNVs) confer high risk for Autism Spectrum Disorder (ASD), schizophrenia (SZ), and Attention-Deficit-Hyperactivity-Disorder (ADHD), but their impact on functional connectivity (FC) remains unclear. Here we report an analysis of resting-state FC using magnetic resonance imaging data from 101 CNV carriers, 755 individuals with idiopathic ASD, SZ, or ADHD and 1,072 controls. We characterize CNV FC-signatures and use them to identify dimensions contributing to complex idiopathic conditions. CNVs have large mirror effects on FC at the global and regional level. Thalamus, somatomotor, and posterior insula regions play a critical role in dysconnectivity shared across deletions, duplications, idiopathic ASD, SZ but not ADHD. Individuals with higher similarity to deletion FC-signatures exhibit worse cognitive and behavioral symptoms. Deletion similarities identified at the connectivity level could be related to the redundant associations observed genome-wide between gene expression spatial patterns and FC-signatures. Results may explain why many CNVs affect a similar range of neuropsychiatric symptoms.
The impact of neurodevelopmental mutations on functional brain connectivity is poorly understood. Here the authors identify thalamo-sensorimotor dysconnectivity dimensions shared across 16p11.2 and 22q11.2 copy number variants, autism and schizophrenia, but not ADHD.
Journal Article
Spatial correspondence of spinal cord white matter tracts using diffusion tensor imaging, fibre tractography, and atlas-based segmentation
by
Cohen-Adad, Julien
,
Hardisty, Michael Raymond
,
Leung, Jason
in
Brain mapping
,
Correspondence
,
Degeneration
2021
Purpose
Neuroimaging provides great utility in complex spinal surgeries, particularly when anatomical geometry is distorted by pathology (tumour, degeneration, etc.). Spinal cord MRI diffusion tractography can be used to generate streamlines; however, it is unclear how well they correspond with white matter tract locations along the cord microstructure. The goal of this work was to evaluate the spatial correspondence of DTI tractography with anatomical MRI in healthy anatomy (where anatomical locations can be well defined in T1-weighted images).
Methods
Ten healthy volunteers were scanned on a 3T system. T1-weighted (1 × 1 × 1 mm) and diffusion-weighted images (EPI readout, 2 × 2 × 2 mm, 30 gradient directions) were acquired and subsequently registered (Spinal Cord Toolbox (SCT)). Atlas-based (SCT) anatomic label maps of the left and right lateral corticospinal tracts were identified for each vertebral region (C2–C6) from T1 images. Tractography streamlines were generated with a customized approach, enabling seeding of specific spinal tract regions corresponding to individual vertebral levels. Spatial correspondence of generated fibre streamlines with anatomic tract segmentations was compared in unseeded regions of interest (ROIs).
Results
Spatial correspondence of the lateral corticospinal tract streamlines was good over a single vertebral ROI (Dice’s similarity coefficient (DSC) = 0.75 ± 0.08, Hausdorff distance = 1.08 ± 0.17 mm). Over larger ROI, fair agreement between tractography and anatomical labels was achieved (two levels: DSC = 0.67 ± 0.13, three levels: DSC = 0.52 ± 0.19).
Conclusion
DTI tractography produced good spatial correspondence with anatomic white matter tracts, superior to the agreement between multiple manual tract segmentations (DSC ~ 0.5). This supports further development of spinal cord tractography for computer-assisted neurosurgery.
Journal Article
A small number of early introductions seeded widespread transmission of SARS-CoV-2 in Québec, Canada
by
Bujold, David
,
Bourque, Guillaume
,
Gregoire, Romain
in
Analysis
,
Bioinformatics
,
Biomedical and Life Sciences
2021
Background
Québec was the Canadian province most impacted by COVID-19, with 401,462 cases as of September 24th, 2021, and 11,347 deaths due mostly to a very severe first pandemic wave. In April 2020, we assembled the Coronavirus Sequencing in Québec (CoVSeQ) consortium to sequence SARS-CoV-2 genomes in Québec to track viral introduction events and transmission within the province.
Methods
Using genomic epidemiology, we investigated the arrival of SARS-CoV-2 to Québec. We report 2921 high-quality SARS-CoV-2 genomes in the context of > 12,000 publicly available genomes sampled globally over the first pandemic wave (up to June 1st, 2020). By combining phylogenetic and phylodynamic analyses with epidemiological data, we quantify the number of introduction events into Québec, identify their origins, and characterize the spatiotemporal spread of the virus.
Results
Conservatively, we estimated approximately 600 independent introduction events, the majority of which happened from spring break until 2 weeks after the Canadian border closed for non-essential travel. Subsequent mass repatriations did not generate large transmission lineages (> 50 sequenced cases), likely due to mandatory quarantine measures in place at the time. Consistent with common spring break and “snowbird” destinations, most of the introductions were inferred to have originated from Europe via the Americas. Once introduced into Québec, viral lineage sizes were overdispersed, with a few lineages giving rise to most infections. Consistent with founder effects, the earliest lineages to arrive tended to spread most successfully. Fewer than 100 viral introductions arrived during spring break, of which 7–12 led to the largest transmission lineages of the first wave (accounting for 52–75% of all sequenced infections). These successful transmission lineages dispersed widely across the province. Transmission lineage size was greatly reduced after March 11th, when a quarantine order for returning travellers was enacted. While this suggests the effectiveness of early public health measures, the biggest transmission lineages had already been ignited prior to this order.
Conclusions
Combined, our results reinforce how, in the absence of tight travel restrictions or quarantine measures, fewer than 100 viral introductions in a week can ensure the establishment of extended transmission chains.
Journal Article
Nonadiabatic asteroseismology of GW vir stars
by
Fontaine, Gilles
,
Quirion, Pierre-Olivier
,
Brassard, Pierre
in
Chemical composition
,
Mathematical analysis
,
Physics
2009
We present results from nonadiabatic stability calculation to determine the position of the GW Vir band in the log g -Teff diagram. With this method, we calculate the position of seven GW Vir stars. The results are consistent with and complementary to the spectroscopic determination of atmospheric parameters and the chemical compositions of these stars except for the newly discover GW Vir star VV 47. This discrepancy is discussed.
Journal Article
Nonadiabatic asteroseismology of GW Vir stars
by
Fontaine, Gilles
,
Quirion, Pierre-Olivier
,
Brassard, Pierre
in
Chemical composition
,
Mathematical analysis
,
Physics
2008
We present and explore a new method involving a nonadiabatic stability calculation to determine the position of the GW Vir band in the log g — Teff diagram. With this method, we calculate the position of two GW Vir stars, PG 1159-035, log g 6.80, Teff 144, 500 K and PG 1707+427, log g 7.38, Teff 81, 500 K. The results are consistent with and complementary to the spectroscopic determination of atmospheric parameters and the chemical compositions of these stars.
Journal Article
Kepler Asteroseismology Program: Introduction and First Results
by
Appourchaux, Thierry
,
Borucki, William J.
,
Gilliland, Ronald L.
in
Acoustic modes
,
Asteroseismology
,
Astronomy
2010
Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius and age, through observations of normal modes of oscillation. The technical requirements for conducting asteroseismology include ultrahigh precision measured in photometry in parts per million, as well as nearly continuous time series over weeks to years, and cadences rapid enough to sample oscillations with periods as short as a few minutes. We report on results from the first 43 days of observations, in which the unique capabilities ofKeplerin providing a revolutionary advance in asteroseismology are already well in evidence. TheKeplerasteroseismology program holds intrinsic importance in supporting the core planetary search program through greatly enhanced knowledge of host star properties, and extends well beyond this to rich applications in stellar astrophysics.
Journal Article
A multi-site campaign on the long period variable subdwarf b star PG 1627+017
2004
We report on the outcome of the first major multi-site campaign on a long-period variable subdwarf B star. The target PG 1627+017 was observed for a total of 334 h during April/May/June 2003 from the lynchpin observatory at Mt. Bigelow, Arizona, with important contributions coming from co-observations at SAAO, Calar Alto and Siding Spring. Preliminary analysis indicates the presence of 8-10 probable periods in the range 64500 to 68900 s with relative amplitudes between 0.1 and 0.5%;. The range over which the periods are found is in qualitative agreement with theoretical predictions and the number of periods found shows potential for an in-depth asteroseismological analysis. Multi-colour observations show that the relative amplitudes of pulsation are larger in the U-band than in the R, which again is in agreement with theory. However, more multi-colour observations are needed to be able to make statements at the quantitative level.
Journal Article
Neuropsychiatric mutations delineate functional brain connectivity dimensions contributing to autism and schizophrenia
by
Labbe, Aurelie
,
Potvin, Stephane
,
Mendrek, Adrianna
in
Attention deficit hyperactivity disorder
,
Autism
,
Brain mapping
2020
16p11.2 and 22q11.2 Copy Number Variants (CNVs) confer high risk for Autism Spectrum Disorder (ASD), schizophrenia (SZ), and Attention-Deficit-Hyperactivity-Disorder (ADHD), but their impact on functional connectivity (FC) remains unclear. We analyzed resting-state functional magnetic resonance imaging data from 101 CNV carriers, 755 individuals with idiopathic ASD, SZ, or ADHD and 1,072 controls. We used CNV FC-signatures to identify dimensions contributing to complex idiopathic conditions. CNVs had large mirror effects on FC at the global and regional level. Thalamus, somatomotor, and posterior insula regions played a critical role in dysconnectivity shared across deletions, duplications, idiopathic ASD, SZ but not ADHD. Individuals with higher similarity to deletion FC-signatures exhibited worse cognitive and behavioural symptoms. Deletion similarities identified at the connectivity level could be related to the redundant associations observed genome-wide between gene expression spatial patterns and FC-signatures. Results may explain why many CNVs affect a similar range of neuropsychiatric symptoms. Competing Interest Statement The authors have declared no competing interest. Footnotes * Extensive efforts have, in particular, been directed towards 1) Demonstrating the robustness of the results by using novel data, performing an array of sensitivity analyses, and systematic comparison with previously published results in autism and schizophrenia 2) Fully reshaping the last section of the manuscript on gene expression. This included analyzing expression data genome-wide and performing a new array of methods that generated results of significant interest. * https://github.com/surchs/Neuropsychiatric_CNV_code_supplement
GenPipes: an open-source framework for distributed and scalable genomic analyses
by
Leveque, Gary
,
Bujold, David
,
Bourque, Guillaume
in
Bioinformatics
,
Computer programs
,
Genomic analysis
2018
With the decreasing cost of sequencing and the rapid developments in genomics technologies and protocols, the need for validated bioinformatics software that enables efficient large-scale data processing is growing. Here we present GenPipes, a flexible Python-based framework that facilitates the development and deployment of multi-step workflows optimized for High Performance Computing clusters and the cloud. GenPipes already implements 12 validated and scalable pipelines for various genomics applications, including RNA-Seq, ChIP-Seq, DNA-Seq, Methyl-Seq, Hi-C, capture Hi-C, metagenomics and PacBio long read assembly. The software is available under a GPLv3 open source license and is continuously updated to follow recent advances in genomics and bioinformatics. The framework has been already configured on several servers and a docker image is also available to facilitate additional installations. In summary, GenPipes offers genomic researchers a simple method to analyze different types of data, customizable to their needs and resources, as well as the flexibility to create their own workflows.