NG2-expressing glial precursor cells are a new potential oligodendroglioma cell initiating population in N-ethyl-N-nitrosourea-induced gliomagenesis.: Brain precursor cells and gliomas

International audienceGliomas are the most common primary brain tumor affecting human adults and remain a therapeutic challenge because cells of origin are still unknown. Here, we investigated the cellular origin of low-grade gliomas in a rat model based on transplacental exposure to N-ethyl-N-nitrosourea (ENU). Longitudinal magnetic resonance imaging coupled to immunohistological and immunocytochemical analyses were used to further characterize low-grade rat gliomas at different stages of evolution. We showed that early low-grade gliomas have characteristics of oligodendroglioma-like tumors and exclusively contain NG2-expressing slow dividing precursor cells, which express early markers of oligodendroglial lineage. These tumor-derived precursors failed to fully differentiate into oligodendrocytes and exhibited multipotential abilities in vitro. Moreover, a few glioma NG2+ cells are resistant to radiotherapy and may be responsible for tumor recurrence, frequently observed in humans. Overall, these findings suggest that transformed multipotent NG2 glial precursor cell may be a potential cell of origin in the genesis of rat ENU-induced oligodendroglioma-like tumors. This work may open up new perspectives for understanding biology of human gliomas

Fuzzy species limits in Mediterranean gorgonians (Cnidaria, Octocorallia): inferences on speciation processes

The study of the interplay between speciation and hybridization is of primary importance in evolutionary biology. Octocorals are ecologically important species whose shallow phylogenetic relationships often remain to be studied. In the Mediterranean Sea, three congeneric octocorals can be observed in sympatry: Eunicella verrucosa, Eunicella cavolini and Eunicella singularis. They display morphological differences and E.singularis hosts photosynthetic Symbiodinium, contrary to the two other species. Two nuclear sequence markers were used to study speciation and gene flow between these species, through network analysis and Approximate Bayesian Computation (ABC). Shared sequences indicated the possibility of hybridization or incomplete lineage sorting. According to ABC, a scenario of gene flow through secondary contact was the best model to explain these results. At the intraspecific level, neither geographical nor ecological isolation corresponded to distinct genetic lineages in E.cavolini. These results are discussed in the light of the potential role of ecology and genetic incompatibilities in the persistence of species limits.French National Research Agency (ANR) program Adacni (ANR) [ANR-12-ADAP-0016]CNRSHubert Curien 'Tassili' program [12MDU853]CCMAR Strategic Plan from Fundacao para a Ciencia e a Tecnologia-FCT [PEst-C/MAR/LA0015/2011,FEDERinfo:eu-repo/semantics/publishedVersio

Using ecosystem-services assessments to determine trade-offs in ecosystem-based management of marine mammals

The goal of ecosystem-based management (EBM) is to support a sustainable and holistic multisectored management approach, and is recognized in a number of international policy frameworks. However, it remains unknown how these goals should be linked to assessments and management plans for marine fauna, such as mammals and fish stocks. It appears particularly challenging to carry out trade-off analyses of various ocean uses without a framework that integrates knowledge of environmental, social, and economic benefits derived from nonstationary marine fauna. We argue this gap can be filled by applying a version of the ecosystem-service approach at the population level of marine fauna. To advance this idea, we used marine mammals as a case study to demonstrate what indicators could operationalize relevant assessments and deliver an evidence base for the presence of ecosystem services and disservices derived from marine mammals. We found indicators covering common ecosystem service categories feasible to apply; examples of indicator data are already available in the literature for several populations. We encourage further exploration of this approach for application to marina fauna and biodiversity management, with the caveat that conceptual tensions related to the use of the ecosystem service concept itself needs to be addressed to ensure acceptance by relevant stakeholders

Adaptive Developmental Delay in Chagas Disease Vectors: An Evolutionary Ecology Approach

The developmental time of vector insects is important to their population dynamics, evolutionary biology, epidemiology of the diseases they transmit, and to their responses to global climatic change. In various triatomine species vectors of Chagas disease (Triatominae, Reduviidae), a delay in the molt of a small proportion of individuals has been observed, and from an evolutionary ecology approach, we propose the hypothesis that the developmental delay is an adaptation to environmental stochasticity through a spreading of risk (bet-hedging) diapause strategy. We confirmed, by means of a survey among specialists, the existence of the developmental delay in triatomines. Statistical descriptions of the developmental time of 11 species of triatomines showed some degree of bi-modality in nine of them. We predicted by means of an optimization model which genotype, coding for a given frequency of developmental diapause, is expected to evolve. We identified a series of parameters that can be measured in the field and in the laboratory to test the hypothesis of an optimal diapause frequency. We also discuss the importance of these findings for triatomines in terms of global climatic change and epidemiological consequences such as their resistance to insecticides

Développements en imagerie RMN spirale et application à la caractérisation de la perméabilité de la barrière hémato-encéphalique sur deux modèles de tumeurs intracérébrales

Ce travail présente les résultats obtenus dans le cadre de développements méthodologiques en imagerie par résonance magnétique. Tout d abord, la mise en place de la technique d imagerie rapide utilisant un échantillonnage de l espace k le long d une trajectoire spirale à densité variable est exposée. L optimisation des paramètres d acquisition et la comparaison de différentes techniques de reconstruction ont été menées via des simulations numériques. Une approche originale de la calibration de la trajectoire dans l espace k est proposée. L imagerie spirale a été utilisée pour mettre en œuvre une méthode de mesure de la perméabilité de la BHE au Gd-DOTA. Ce protocole a été intégré aux mesures de volume sanguin et d index de taille des vaisseaux utilisant le Sinerem®. Les résultats obtenus montrent des différences au niveau des paramètres de la microvascularisation sur les modèles de tumeurs C6 et RG2. La présence du Sinerem® conduit à une diminution des valeurs de constante d échange à travers la paroi vasculaire (Ktrans) dans la tumeur de 24% en moyenne. Cette étude a également mis en évidence l extravasation du Sinerem®, pendant les deux premières heures après injection du produit, uniquement dans les tumeurs RG2.The results presented in this work were obtained as part of methodological developments in magnetic resonance imaging. First of all, the setting of the rapid imaging technique using a k-space sampling scheme along a variable density spiral is described. Numerical simulations were used to optimize the acquisitions parameters and to compare different reconstruction techniques. An original approach to calibrate the k-space trajectory was proposed. Then, spiral imaging was used to implement a method to measure the blood brain barrier permeability to Gd-DOTA. This protocol was combined to blood volume and vessel size index measurements using Sinerem®. The results obtained highlighted differences between the microvascular parameters measured on C6 and RG2 tumor models. The presence of Sinerem® induces a mean decrease of the transfer constant across the vascular wall (Ktrans), in the tumor, of 24%. This study also showed extravasation of the Sinerem®, during the first two hours after the product injection, only in the RG2 tumors.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Mise en place d'une mesure quantitative du T1 en IRM cardiaque

La cartographie du temps de relaxation longitudinale T1 est une technique d'IRM quantitative pour caractériser les tissus myocardiques. Plusieurs études ont déjà montré la corrélation entre la mesure de T1 et la présence de fibrose. Celle-ci est souvent observée dans les pathologies cardiaques telles que les cardiomyopathies ou l'infarctus du myocarde. Cependant, l'acquisition d'une carte T1 du coeur reste techniquement difficile. Actuellement, la quantification T1 du myocarde humain est réalisée en apnée à l'aide de séquences 2D qui sont spécifiques aux constructeurs et donc peu disponibles. Afin de pallier aux limitations de ces séquences, nous proposons une méthode basée sur une séquence 3D clinique. Cette technique, utilisant la variation des angles de bascule avec intégration d'une correction B1, a été adaptée pour une utilisation en imagerie cardiaque. Des essais sur fantôme ont permis de sélectionner les paramètres optimaux et de montrer la reproductibilité de la méthode. Puis, une étude sur volontaires sains a permis de valider la méthode en double synchronisation (cardiaque et respiratoire). Enfin, une méthode de reconstruction intégrant des signaux physiologiques de mouvement a également été utilisée afin de faire de la quantification T1 en respiration libre et de diminuer le temps d'acquisition. Les valeurs de T1 myocardique sur volontaires sont comprises entre 1289 +- 66 ms et 1376 +- 43 ms, correspondant aux valeurs de la littérature. Ces travaux ouvrent la voie à l'utilisation de la cartographie T1 chez les patients avec pour objectifs une meilleure caractérisation des pathologies et une meilleure adaptation des stratégies thérapeutiquesT1 mapping is a useful quantitative MR technique for cardiac tissue characterization. Several studies have shown that T1 measurements are correlated with fibrosis, which is observed in cardiac diseases such as cardiomyopathy or myocardial infarction. However, cardiac T1 mapping remains challenging, mainly because of long acquisition times and interference from cardiac and respiratory motions. T1 quantification on the human myocardium is generally performed on breath-hold with 2D specific sequences. Unfortunately these sequences are scanner specific and poorly available for clinical use. To overcome these limitations, we propose a new method based on a 3D clinical sequence. This technique, using a variable flip angle approach that integrates B1 correction, was adapted in cardiac imaging. Phantom tests were used to select the optimal parameters and to show the method reproducibility. Then, the method was validated with a volunteer study using double synchronization (cardiac and respiratory). Moreover, a reconstruction method integrating physiological signals of motion was also used to perform T1 quantification in free breathing and to reduce the total acquisition time. The myocardial T1 values on volunteers ranged between 1289 +- 66 ms and 1376 +- 43 ms, which was in good agreement with previously published works. These studies allow the use of T1 mapping in patients with better characterization of pathologies and a better adaptation to therapeutic strategiesMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

First trimester screening for pre-eclampsia and intrauterine growth restriction using three-dimensional Doppler angiography (SPIRIT): protocol for a multicentre prospective study in nulliparous pregnant women

International audienceTo cite: Bertholdt C, Hossu G, Banasiak C, et al. First trimester screening for pre-eclampsia and intrauterine growth restriction using three-dimensional Doppler angiography (SPIRIT): protocol for a multicentre prospective study in nulliparous pregnant women. BMJ Open 2020;10:e037751

The acellular matrix (ACM) for bladder tissue engineering: A quantitative magnetic resonance imaging study

This is the peer reviewed version of the following article: Cheng,H.‐ L.M., Loai, Y., Beaumont, M. and Farhat, W.A. (2010), The acellular matrix (ACM) for bladder tissue engineering: A quantitative magnetic resonance imaging study. Magn. Reson. Med., 64: 341-348. doi:10.1002/mrm.22404, which has been published in final form at https://doi.org/10.1002/mrm.22404. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Bladder acellular matrices (ACMs) derived from natural tissue are gaining increasing attention for their role in tissue engineering and regeneration. Unlike conventional scaffolds based on biodegradable polymers or gels, ACMs possess native biomechanical and many acquired biologic properties. Efforts to optimize ACM-based scaffolds are ongoing and would be greatly assisted by a noninvasive means to characterize scaffold properties and monitor interaction with cells. MRI is well suited to this role, but research with MRI for scaffold characterization has been limited. This study presents initial results from quantitative MRI measurements for bladder ACM characterization and investigates the effects of incorporating hyaluronic acid, a natural biomaterial useful in tissue-engineering and regeneration. Measured MR relaxation times (T(1), T(2)) and diffusion coefficient were consistent with increased water uptake and glycosaminoglycan content observed on biochemistry in hyaluronic acid ACMs. Multicomponent MRI provided greater specificity, with diffusion data showing an acellular environment and T(2) components distinguishing the separate effects of increased glycosaminoglycans and hydration. These results suggest that quantitative MRI may provide useful information on matrix composition and structure, which is valuable in guiding further development using bladder ACMs for organ regeneration and in strategies involving the use of hyaluronic acid.This work was supported by funds from the Canadian Institutes of Health Research (Institute of Human Development, Child, and Youth Health) and The Hospital for Sick Children Foundation to H.-L.M.C. We thank Dr.Greg Stanisz for the CPMG sequence

Characterization of tumor angiogenesis in rat brain using iron-based vessel size index MRI in combination with gadolinium-based dynamic contrast-enhanced MRI.: Combined VSI and DCE MRI

International audienceThis study aimed at combining an iron-based, steady-state, vessel size index magnetic resonance imaging (VSI MRI) approach, and a gadolinium (Gd)-based, dynamic contrast-enhanced MRI approach (DCE MRI) to characterize tumoral microvasculature. Rats bearing an orthotopic glioma (C6, n=14 and RG2, n=6) underwent DCE MRI and combined VSI and DCE MRI 4 h later, at 2.35 T. Gd-DOTA (200 mumol of Gd per kg) and ultrasmall superparamagnetic iron oxide (USPIO) (200 micromol of iron per kg) were used for DCE and VSI MRI, respectively. C6 and RG2 gliomas were equally permeable to Gd-DOTA but presented different blood volume fractions and VSI, in good agreement with histologic data. The presence of USPIO yielded reduced K(trans) values. The K(trans) values obtained with Gd-DOTA in the absence and in the presence of USPIO were well correlated for the C6 glioma but not for the RG2 glioma. It was also observed that, within the time frame of DCE MRI, USPIO remained intravascular in the C6 glioma whereas it extravasated in the RG2 glioma. In conclusion, VSI and DCE MRI can be combined provided that USPIO does not extravasate with the time frame of the DCE MRI experiment. The mechanisms at the origin of USPIO extravasation remain to be elucidated