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A molecularly defined subpopulation of oligodendrocyte precursor cells controls the generation of myelinating oligodendrocytes during postnatal development
No full textInternational audienceOligodendrocyte precursor cells (OPCs) are a class of glial cells that uniformly tiles the entire central nervous system (CNS). They play several key functions across the brain including the generation of oligodendrocytes and the control of myelination. Whether the functional diversity of OPCs is the result of genetically defined subpopulations or of their regulation by external factors has not been definitely established. We discovered that a subpopulation of OPCs found across the brain is defined by the expression of C1ql1 , a gene previously described for its synaptic function in neurons. This subpopulation starts to appear during the first postnatal week in the mouse cortex. Ablation of C1ql1 -expressing OPCs in the mouse leads to a massive lack of oligodendrocytes and myelination in many brain regions. This deficit cannot be rescued, even though some OPCs escape Sox10 -driven ablation and end up partially compensating the OPC loss in the adult. Therefore, C1ql1 is a molecular marker of a functionally non-redundant subpopulation of OPCs, which controls the generation of myelinating oligodendrocytes
Les Fragments Secrets des Instructions Orales, extraits de l’Exégèse Essentielle des Ḍākinīs (mKha’ ‘gro snying gi ti ka las : zhal gdams gsang ba’i dum bu)
No full textX-ray Radiotherapy Impacts Cardiac Dysfunction by Modulating the Sympathetic Nervous System and Calcium Transients
No full textInternational audienceRecent epidemiological studies have shown that patients with right-sided breast cancer (RBC) treated with X-ray irradiation (IR) are more susceptible to developing cardiovascular diseases, such as arrhythmias, atrial fibrillation, and conduction disturbances after radiotherapy (RT). Our aim was to investigate the mechanisms induced by low to moderate doses of IR and to evaluate changes in the cardiac sympathetic nervous system (CSNS), atrial remodeling, and calcium homeostasis involved in cardiac rhythm. To mimic the RT of the RBC, female C57Bl/6J mice were exposed to X-ray doses ranging from 0.25 to 2 Gy targeting 40% of the top of the heart. At 60 weeks after RI, Doppler ultrasound showed a significant reduction in myocardial strain, ejection fraction, and atrial function, with a significant accumulation of fibrosis in the epicardial layer and apoptosis at 0.5 mGy. Calcium transient protein expression levels, such as RYR2, NAK, Kir2.1, and SERCA2a, increased in the atrium only at 0.5 Gy and 2 Gy at 24 h, and persisted over time. Interestingly, 3D imaging of the cleaned hearts showed an early reduction of CSNS spines and dendrites in the ventricles and a late reorientation of nerve fibers, combined with a decrease in SEMA3a expression levels. Our results showed that local heart IR from 0.25 Gy induced late cardiac and atrial dysfunction and fibrosis development. After IR, ventricular CSNS and calcium transient protein expression levels were rearranged, which affected cardiac contractility. The results are very promising in terms of identifying pro-arrhythmic mechanisms and preventing arrhythmias during RT treatment in patients with RBC
Multiple-scale gas infall through gravity torques on Milky Way twins
No full textInternational audienceOne of the main problems raised by the feeding of super-massive black holes (SMBHs) at the centres of galaxies is the huge angular momentum of the circumnuclear gas and of the gas reservoir in the galaxy disk. Because viscous torques are not efficient at kiloparsec or 100 pc scales, the angular momentum must be exchanged through gravity torques that arise from the non-axisymmetric patterns in the disks. Our goal here is to quantify the efficiency of bars and spirals in driving the gas towards the centre at different scales in galaxies. We selected a sample of nearby galaxies considered to be analogues of the Milky Way, that is, galaxies of late morphological type Sbc. Their bar strength was variable, either SB, or SAB, or SA, so that we were able to quantify the influence of the bar. The gravitational potential was computed from deprojected red images, either from Hubble Space Telescope or Legacy survey, depending on the spatial resolution and field of view considered. The torques were computed on the gas through CO emission maps from ALMA at different resolutions. Hα maps from MUSE were used, when available. Eight out of ten galaxies are barred. The torques are found to be negative in the eight barred objects at kiloparsec scales, between corotation and the inner Lindblad resonance (ILR), with a loss of angular momentum in a few rotations. Inside the ILR, the torques are negative in only five cases, with a timescale of one to two rotations. The torques are positive for the galaxies without bars. The torques applied on the ionized gas are comparable to what is deduced from molecular gas. The bars are confirmed to be the essential pattern in the SMBH feeding at kiloparsec and 100 pc scales; higher-resolution gas maps are required to explore scales of 10 pc
Estimating HPV16 genome copy number per infected cell in cervical smears
No full textHuman papillomavirus (HPV) 16 is the most oncogenic biological agents for humans. However, essential quantitative aspects of its infection cycle remain inadequately characterized. Specifically, the proportion of infected cells and the viral copy number per infected cell in cervical smears are not well understood. To address this, we employed a combination of limiting dilution techniques and Bayesian statistics on routine cervical smears to estimate the frequency of infected cells and the viral copy number per cell. Our methodology was initially validated through numerical simulations and cell culture experiments. Subsequently, we analyzed 38 HPV16-positive cervical smears, comprising 26 samples from patients without cytological lesions and 12 from patients with low-grade lesions. Our findings indicated that the substantial variability in viral load across samples predominantly stemmed from differences in the frequency of infected cells. Additionally, the mean number of HPV copies per infected cell was consistently low across all samples, ranging from approximately 2.3 to 100 copies. However, in samples with low-grade lesionMarie-Paule Algross, this number was observed to double on average. These results challenge existing assumptions regarding the biology of HPV genital infections, which are typically asymptomatic or minimally symptomatic.</div
Disruptions du développement humain
No full textInternational audienceLes biologistes décrivent actuellement une multitude de disruptions ayant lieu à tous les niveaux d’organisation du vivant, humains et non-humains. Ces disruptions proviennent principalement des technologies, qu’il s’agisse de la machine thermique issue de la première révolution industrielle, et du changement climatique subséquent, de la chimie avec notamment les perturbateurs endocriniens qui en sont issus, ou du numérique avec l’immixtion des écrans dans la relation parents-jeunes enfants (dans le cas des humains). Les infidélités du milieu ne sont pas étrangères au vivant comme le soulignait Canguilhem, mais la spécificité de ces disruption est leur rythme qui excède les capacité normative du vivant, humain et non-humain, conduisant à une contrepartie biologique de ce que Stiegler appelait la disruption comme régime actuel des sociétés humaines.Nous insisterons sur les conséquences de ces disruptions concernant le développement humain, biologique et psychique, et nous indiquerons des réponses possibles face à ces disruptions
Compte-rendu : Lucy Parker, Symeon Stylites the Younger and Late Antique Antioch. From Hagiography to History (Oxford Studies in Byzantium). – Oxford University Press, Oxford 2022. 24 × 16 ; relié. viii-270 p., 5 fig. en noir et blanc. Prix : 81 £. ISBN 978-0-19-286517-5.
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Ian C. Cunningham (editionem post Kurt Latte continuans recensuit et emendauit), Hesychii Alexandrini Lexicon. IIa, E-I ; IIb, K-O (Sammlung griechischer und lateinischer Grammatiker 11.2a-b). – De Gruyter, Berlin, Boston 2020. 23,5 × 16 ; relié. xii-1000 p. Prix : 280 €.ISBN 978-3-11-066719-6.
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