L'essor de la radiothérapie conformationnelle et de la radiothérapie guidée par l'image a pour corollaire l'accroissement du temps consacré à la délinéation des volumes d'intérêt, qui est également ...le siège d'une variabilité inter et intraobservateur. Les développements informatiques et du traitement d'images ont permis des progrès dans l'automatisation partielle ou totale de ces tâches. Cet article détaille les grands principes de la segmentation d'images appliquée à la radiothérapie, ses applications ainsi que ses résultats les plus récents dans un contexte clinique.
Amphibian metamorphosis involves extensive, but selective, neuronal death and turnover, thus sharing many features with mammalian postnatal development. The antiapoptotic protein Bcl-XLplays an ...important role in postnatal mammalian neuronal survival. It is therefore of interest that accumulation of the mRNA encoding the Xenopus Bcl-XLhomologue, termed xR11, increases abruptly in the nervous system, but not in other tissues, during metamorphosis in Xenopus tadpoles. This observation raises the intriguing possibility that xR11 selectively regulates neuronal survival during postembryonic development. To investigate this hypothesis, we overexpressed xR11 in vivo as a green fluorescent protein (GFP)-xR11 fusion protein by using somatic and germinal transgenesis. Somatic gene transfer showed that the fusion protein was effective in counteracting, in a dose-dependent manner, the proapoptotic effects of coexpressed Bax. When GFP-xR11 was expressed from the neuronal β-tubulin promoter by germinal transgenesis we observed neuronal specific expression that was maintained throughout metamorphosis and beyond, into juvenile and adult stages. Confocal microscopy showed GFP-xR11 to be exclusively localized in the mitochondria. Our findings show that GFP-xR11 significantly prolonged Rohon-Beard neuron survival up to the climax of metamorphosis, even in the regressing tadpole tail, whereas in controls these neurons disappeared in early metamorphosis. However, GFP-xR11 expression did not modify the fate of spinal cord motoneurons. The selective protection of Rohon-Beard neurons reveals cell-specific apoptotic pathways and offers approaches to further analyze programmed neuronal turnover during postembryonic development.
La radiothérapie fait partie des traitements à visée curative des tumeurs malignes. Les techniques de radiothérapie ont considérablement évolué ces dernières années avec l' intégration croissante de ...l'imagerie en radiothérapie conformationnelle. Cette technique permet d'élaborer une balistique complexe se conformant le mieux possible au volume cible en préservant les tissus sains. L'examen utilisé pour la définition des volumes d'intérêt est actuellement la tomodensitométrie ou « scanner » en raison de son exactitude géométrique et de l'information donnée sur les densités électroniques utilisées pour les calculs dosimétriques. L'Imagerie par Résonance Magnétique (IRM) permet cependant une définition plus précise des volumes cibles dans les localisations pelviennes et cérébrales. Dans le cadre des localisations pelviennes, l'utilisation de l'IRM passe à l'heure actuelle par la fusion d'images, ce qui complexifie la phase de préparation du traitement et pose le problème de l'absence de méthode « standard » de validation in vivo de cette fusion d'images. Nous avons évalué les contraintes posées par l'utilisation de l'IRM seule dans la planification dosimétrique. Nos résultats montrent que ni la distorsion liée au système et au patient ni l'absence d'informations sur les densités électroniques ne représentent des obstacles rédhibitoires à l'utilisation de l'IRM seule dans ce contexte. La distorsion reste contenue y compris en bordure de grands champs de vue sur des machines modernes. Nous avons montré que l'assignation de densités aux structures osseuses et aux tissus mous permettait d'obtenir une dosimétrie équivalente à celle réalisée sur le scanner original avec une bonne reproductibilité et une répartition de dose homogène au sein du volume cible. L'assignation de densités électroniques pourrait même ne pas être réalisée avec des photons de 20 MV et une balistique appropriée. Le développement de la radiothérapie guidée par l'image pourrait faciliter l'utilisation de l'IRM seule dans la planification dosimétrique. La délinéation des volumes d'intérêt est une tâche nécessitant de plus en plus de temps. Nous avons participé au développement et évalué une méthode de segmentation automatique et semi automatique des volumes d'intérêt d'après des images IRM pour la radiothérapie du cancer prostatique. La délinéation automatique de la prostate repose sur un modèle d'organe déformable; une méthode par extension de régions a été utilisée pour la délinéation du rectum et de la vessie. Nos résultats sont reproductibles et le retentissement dosimétrique de la délinéation automatique est minime.
We present a measurement of baryon acoustic oscillations (BAO) in the cross-correlation of quasars with the Lyα-forest flux transmission at a mean redshift of z = 2.40. The measurement uses the ...complete Sloan Digital Sky Survey (SDSS-III) data sample: 168 889 forests and 234 367 quasars from the SDSS data release DR12. In addition to the statistical improvement on our previous study using DR11, we have implemented numerous improvements at the analysis level enabling a more accurate measurement of this cross-correlation. We have also developed the first simulations of the cross-correlation that allow us to test different aspects of our data analysis and to search for potential systematic errors in the determination of the BAO peak position. We measure the two ratios DH(z = 2.40) /rd = 9.01 ± 0.36 and DM(z = 2.40) /rd = 35.7 ± 1.7, where the errors include marginalization over the non-linear velocity of quasars and the cross-correlation of metals and quasars, among other effects. These results are within 1.8σ of the prediction of the flat-ΛCDM model describing the observed cosmic microwave background anisotropies. We combine this study with the Lyα-forest auto-correlation function, yielding DH(z = 2.40) /rd = 8.94 ± 0.22 and DM(z = 2.40) /rd = 36.6 ± 1.2, within 2.3σ of the same flat-ΛCDM model.
We have used flux-transmission correlations in Lyα forests to measure the imprint of baryon acoustic oscillations (BAO). The study uses spectra of 157 783 quasars in the redshift range 2.1 ≤ z ≤ 3.5 ...from the Sloan Digital Sky Survey (SDSS) data release 12 (DR12). Besides the statistical improvements on our previous studies using SDSS DR9 and DR11, we have implemented numerous improvements in the analysis procedure, allowing us to construct a physical model of the correlation function and to investigate potential systematic errors in the determination of the BAO peak position. The Hubble distance, DH = c/H(z), relative to the sound horizon is DH(z = 2.33) /rd = 9.07 ± 0.31. The best-determined combination of comoving angular-diameter distance, DM, and the Hubble distance is found to be DH0.7DM0.3 /rd = 13.94 ± 0.35. This value is 1.028 ± 0.026 times the prediction of the flat-ΛCDM model consistent with the cosmic microwave background (CMB) anisotropy spectrum. The errors include marginalization over the effects of unidentified high-density absorption systems and fluctuations in ultraviolet ionizing radiation. Independently of the CMB measurements, the combination of our results and other BAO observations determine the open-ΛCDM density parameters to be ΩM = 0.296 ± 0.029, ΩΛ = 0.699 ± 0.100 and Ωk = −0.002 ± 0.119.
Recent studies highlighted the importance of astrocytes in neuroinflammatory diseases, interacting closely with other CNS cells but also with the immune system. However, due to the difficulty in ...obtaining human astrocytes, their role in these pathologies is still poorly characterized. Here, we develop a serum-free protocol to differentiate human induced pluripotent stem cells (hiPSCs) into astrocytes. Gene expression and functional assays show that our protocol consistently yields a highly enriched population of resting mature astrocytes across the 13 hiPSC lines differentiated. Using this model, we first highlight the importance of serum-free media for astrocyte culture to generate resting astrocytes. Second, we assess the astrocytic response to IL-1β, TNF-α, and IL-6, all cytokines important in neuroinflammation, such as multiple sclerosis. Our study reveals very specific profiles of reactive astrocytes depending on the triggering stimulus. This model provides ideal conditions for in-depth and unbiased characterization of astrocyte reactivity in neuroinflammatory conditions.
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•Human iPSCs are differentiated from blood of control and multiple sclerosis subjects•Functional astrocytes are differentiated from hiPSC in serum-free conditions•In-depth characterization of the effect of serum on astrocyte phenotype•Multiple sclerosis cytokines trigger specific activation profiles in astrocytes
Perriot et al. describe a new protocol to differentiate both resting and reactive astrocytes from human induced pluripotent stem cells in serum-free conditions. They show that astrocytes exhibit highly contrasted responses to serum and to cytokines involved in multiple sclerosis, establishing that this model is suitable to study neuroinflammation.
For many decades, invertebrate immunity was believed to be non-adaptive, poorly specific, relying exclusively on sometimes multiple but germ-line encoded innate receptors and effectors. But recent ...studies performed in different invertebrate species have shaken this paradigm by providing evidence for various types of somatic adaptations at the level of putative immune receptors leading to an enlarged repertoire of recognition molecules. Fibrinogen Related Proteins (FREPs) from the mollusc Biomphalaria glabrata are an example of these putative immune receptors. They are known to be involved in reactions against trematode parasites. Following not yet well understood somatic mechanisms, the FREP repertoire varies considerably from one snail to another, showing a trend towards an individualization of the putative immune repertoire almost comparable to that described from vertebrate adaptive immune system. Nevertheless, their antigenic targets remain unknown. In this study, we show that a specific set of these highly variable FREPs from B. glabrata forms complexes with similarly highly polymorphic and individually variable mucin molecules from its specific trematode parasite S. mansoni (Schistosoma mansoni Polymorphic Mucins: SmPoMucs). This is the first evidence of the interaction between diversified immune receptors and antigenic variant in an invertebrate host/pathogen model. The same order of magnitude in the diversity of the parasite epitopes and the one of the FREP suggests co-evolutionary dynamics between host and parasite regarding this set of determinants that could explain population features like the compatibility polymorphism observed in B. glabrata/S. mansoni interaction. In addition, we identified a third partner associated with the FREPs/SmPoMucs in the immune complex: a Thioester containing Protein (TEP) belonging to a molecular category that plays a role in phagocytosis or encapsulation following recognition. The presence of this last partner in this immune complex argues in favor of the involvement of the formed complex in parasite recognition and elimination from the host.
•Comparative immunologists are facing many challenges that can be solved using NGS.•NGS will circumvent the need for genome sequences in non-model species.•NGS can be applied to gene discovery, ...expression profiling and association studies.•NGS can be used to study the mechanisms of diversification of immune receptors.•NGS will reveal the role of epigenetics in immune genes expression and diversity.
Next generation sequencing (NGS) allows for the rapid, comprehensive and cost effective analysis of entire genomes and transcriptomes. NGS provides approaches for immune response gene discovery, profiling gene expression over the course of parasitosis, studying mechanisms of diversification of immune receptors and investigating the role of epigenetic mechanisms in regulating immune gene expression and/or diversification. NGS will allow meaningful comparisons to be made between organisms from different taxa in an effort to understand the selection of diverse strategies for host defence under different environmental pathogen pressures. At the same time, it will reveal the shared and unique components of the immunological toolkit and basic functional aspects that are essential for immune defence throughout the living world. In this review, we argue that NGS will revolutionize our understanding of immune responses throughout the animal kingdom because the depth of information it provides will circumvent the need to concentrate on a few “model” species.
There is a lack of validated biomarkers for disability progression independent of relapse activity (PIRA) in multiple sclerosis (MS).
To determine how serum glial fibrillary acidic protein (sGFAP) ...and serum neurofilament light chain (sNfL) correlate with features of disease progression vs acute focal inflammation in MS and how they can prognosticate disease progression.
Data were acquired in the longitudinal Swiss MS cohort (SMSC; a consortium of tertiary referral hospitals) from January 1, 2012, to October 20, 2022. The SMSC is a prospective, multicenter study performed in 8 centers in Switzerland. For this nested study, participants had to meet the following inclusion criteria: cohort 1, patients with MS and either stable or worsening disability and similar baseline Expanded Disability Status Scale scores with no relapses during the entire follow-up; and cohort 2, all SMSC study patients who had initiated and continued B-cell-depleting treatment (ie, ocrelizumab or rituximab).
Patients received standard immunotherapies or were untreated.
In cohort 1, sGFAP and sNfL levels were measured longitudinally using Simoa assays. Healthy control samples served as the reference. In cohort 2, sGFAP and sNfL levels were determined cross-sectionally.
This study included a total of 355 patients (103 29.0% in cohort 1: median IQR age, 42.1 33.2-47.6 years; 73 female patients 70.9%; and 252 71.0% in cohort 2: median IQR age, 44.3 33.3-54.7 years; 156 female patients 61.9%) and 259 healthy controls with a median IQR age of 44.3 36.3-52.3 years and 177 female individuals (68.3%). sGFAP levels in controls increased as a function of age (1.5% per year; P < .001), were inversely correlated with BMI (-1.1% per BMI unit; P = .01), and were 14.9% higher in women than in men (P = .004). In cohort 1, patients with worsening progressive MS showed 50.9% higher sGFAP levels compared with those with stable MS after additional sNfL adjustment, whereas the 25% increase of sNfL disappeared after additional sGFAP adjustment. Higher sGFAP at baseline was associated with accelerated gray matter brain volume loss (per doubling: 0.24% per year; P < .001) but not white matter loss. sGFAP levels remained unchanged during disease exacerbations vs remission phases. In cohort 2, median (IQR) sGFAP z scores were higher in patients developing future confirmed disability worsening compared with those with stable disability (1.94 0.36-2.23 vs 0.71 -0.13 to 1.73; P = .002); this was not significant for sNfL. However, the combined elevation of z scores of both biomarkers resulted in a 4- to 5-fold increased risk of confirmed disability worsening (hazard ratio HR, 4.09; 95% CI, 2.04-8.18; P < .001) and PIRA (HR, 4.71; 95% CI, 2.05-9.77; P < .001).
Results of this cohort study suggest that sGFAP is a prognostic biomarker for future PIRA and revealed its complementary potential next to sNfL. sGFAP may serve as a useful biomarker for disease progression in MS in individual patient management and drug development.
Objective
Neurofilament light chains (NfL) are unique to neuronal cells, are shed to the cerebrospinal fluid (CSF), and are detectable at low concentrations in peripheral blood. Various diseases ...causing neuronal damage have resulted in elevated CSF concentrations. We explored the value of an ultrasensitive single‐molecule array (Simoa) serum NfL (sNfL) assay in multiple sclerosis (MS).
Methods
sNfL levels were measured in healthy controls (HC, n = 254) and two independent MS cohorts: (1) cross‐sectional with paired serum and CSF samples (n = 142), and (2) longitudinal with repeated serum sampling (n = 246, median follow‐up = 3.1 years, interquartile range IQR = 2.0–4.0). We assessed their relation to concurrent clinical, imaging, and treatment parameters and to future clinical outcomes.
Results
sNfL levels were higher in both MS cohorts than in HC (p < 0.001). We found a strong association between CSF NfL and sNfL (β = 0.589, p < 0.001). Patients with either brain or spinal (43.4pg/ml, IQR = 25.2–65.3) or both brain and spinal gadolinium‐enhancing lesions (62.5pg/ml, IQR = 42.7–71.4) had higher sNfL than those without (29.6pg/ml, IQR = 20.9–41.8; β = 1.461, p = 0.005 and β = 1.902, p = 0.002, respectively). sNfL was independently associated with Expanded Disability Status Scale (EDSS) assessments (β = 1.105, p < 0.001) and presence of relapses (β = 1.430, p < 0.001). sNfL levels were lower under disease‐modifying treatment (β = 0.818, p = 0.003). Patients with sNfL levels above the 80th, 90th, 95th, 97.5th, and 99th HC‐based percentiles had higher risk of relapses (97.5th percentile: incidence rate ratio = 1.94, 95% confidence interval CI = 1.21–3.10, p = 0.006) and EDSS worsening (97.5th percentile: OR = 2.41, 95% CI = 1.07–5.42, p = 0.034).
Interpretation
These results support the value of sNfL as a sensitive and clinically meaningful blood biomarker to monitor tissue damage and the effects of therapies in MS. Ann Neurol 2017;81:857–870
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