Modelling of winter wheat carbon assimilation from sun induced fluorescence (SIF)

editorial reviewe

Structural and electrical properties of tellurovanadate glasses containing Li2O

Glassy materials are promising intercalation compounds, due to their open network structure and absence of grain boundaries. Some glasses containing alkali ions and a high concentration of transition metal ions can present mixed ionic-electronic conductivity and are therefore potential candidates for application as cathode material in Li-ion batteries. The present work is devoted to the ternary system xLi(2)O-(1-x)[0.3V(2)O(5)-0.7TeO(2)] with 0 <= x <= 0.4. These compounds were prepared by heat treatment in air at 800 degrees C followed by traditional quenching. Raman spectroscopy and V-51 nuclear magnetic resonance measurements were performed in order to highlight the structural short range order modifications induced by the introduction of the Li2O network modifier. These structural effects can be related to the electrical behaviour, as studied by complex impedance spectroscopy measurements. (c) 2006 Elsevier B.V. All rights reserved

Est-ce que le genre influence la tolérance myocardique à l'ischémie-reperfusion dans un modèle de rat prédiabétique ?

International audienceObjectifs : Le prédiabète est un facteur de risque de diabète de type 2 et de complications cardiovasculaires comme l'infarctus du myocarde [1, 2]. Cependant peu d'études explorent les effets du genre dans ce contexte. L'objectif de cette étude a été de comparer les effets d'un régime riche en graisse et en sucre (HFS) sur la sensibilité du myocarde à un épisode d'ischémie-reperfusion chez des rats mâles et femelles. Matériels et méthodes : Pendant cinq mois, des rats Wistar mâles et femelles ont reçu un régime HFS (M-HFS et F-HFS) ou standard (M-CTRL et F-CTRL). Ensuite, des expériences ex vivo sur le modèle du coeur isolé perfusé ont été réalisées afin d'évaluer la tolérance à un épisode d'ischémie-reperfusion. Les coeurs ont été perfusé avec un tampon physiologique contenant du palmitate pendant 24 minutes, avant de subir une ischémie à faible flux et une reperfusion de 32 minutes chacune. Le métabolisme énergétique (ATP, PCr, Pi) et le pH intracellulaire ont été mesurés pendant tout le protocole à l'aide de la SRM du phosphore-31, en simultané avec la mesure de la fonction cardiaque. A la fin des expériences, les coeurs ont été conservés à-80°C pour des analyses biochimiques ultérieures. Résultats : Après cinq mois, le régime HFS a induit une prise de poids uniquement chez les M-HFS vs. M-CTRL, mais pas chez les F-HFS vs. F-CTRL. Le pourcentage de masse grasse est significativement augmenté chez les M-HFS et F-HFS vs. leurs CTRL respectifs. Dans les deux sexes, une intolérance au glucose et une hyperglycémie modérée à jeun a été observée avec le régime HFS (vs. CTRL respectifs), avec une intolérance au glucose plus marquée chez les F-HFS vs. M-HFS. Le ratio poids du coeur / longueur du tibia, utilisé comme marqueur d'hypertrophie cardiaque, est augmenté uniquement chez les M-HFS vs. M-CTRL. Ex vivo, le régime HFS n'a pas induit d'altérations de la fonction cardiaque et du métabolisme énergétique en conditions basales. Cependant à la reperfusion, une altération de la fonction cardiaque et du métabolisme énergétique (ATP et PCr) a été observée chez les mâles et femelles HFS (vs. CTRL respectifs), sans effet du sexe. Afin d'approfondir les mécanismes impliqués dans les altérations induites par le régime HFS, nous étudierons dans les coeurs le pourcentage en eau, le stress oxydant (MDA), la fonction mitochondriale (citrate synthase) et la fonction endothéliale (voie du NO). Conclusion : Cinq mois de régime HFS a induit le développement d'un prédiabète chez des femelles et des mâles Wistar, avec des différences entre les sexes concernant la tolérance au glucose et l'hypertrophie cardiaque. Le régime HFS a également diminué la tolérance myocardique à un épisode d'ischémie-reperfusion, sans effet du sexe. Références : [1] Grundy S.M., Pre-diabetes, metabolic syndrome, and cardiovascular risk, J Am Col

Female hormones prevent sepsis-induced cardiac dysfunction: an experimental randomized study

Although epidemiologic research has demonstrated significant differences in incidence and outcomes of sepsis according to sex, their underlying biological mechanisms are poorly understood. Here, we studied the influence of hormonal status by comparing in vivo cardiac performances measured by MRI in non-ovariectomized and ovariectomized septic female rats. Control and ovariectomized rats were randomly allocated to the following groups: sham, sepsis and sepsis plus landiolol. Sepsis was induced by caecum ligation and punction (CLP). Landiolol, a short-acting selective β1-adrenergic blocker improving the in vivo cardiac performance of septic male rats was perfused continuously after sepsis induction. Cardiac MRI was carried out 18 h after induction of sepsis to assess in vivo cardiac function. Capillary permeability was evaluated by Evans Blue administration and measurement of its tissue extravasation. Variation in myocardial gene and protein expression was also assessed by qPCR and western-blot in the left ventricular tissue. Sepsis reduced indexed stroke volume, cardiac index and indexed end-diastolic volume compared to sham group in ovariectomized females whereas it had no effect in control females. This was associated with an overexpression of JAK2 expression and STAT3 phosphorylation on Ser727 site, and an inhibition of the adrenergic pathways in OVR females. Landiolol increased the indexed stroke volume by reversing the indexed end-diastolic volume reduction after sepsis in ovariectomized females, while it decreased indexed stroke volume and cardiac index in control. This was supported by an overexpression of genes involved in calcium influx in OVR females while an inactivation of the β-adrenergic and a calcium efflux pathway was observed in control females. Sepsis decreased in vivo cardiac performances in ovariectomized females but not in control females, presumably associated with a more pronounced inflammation, inhibition of the adrenergic pathway and calcium efflux defects. Administration of landiolol prevents this cardiac dysfunction in ovariectomized females with a probable activation of calcium influx, while it has deleterious effects in control females in which calcium efflux pathways were down-regulated

The Subventricular Zone, a Hideout for Adult and Pediatric High-Grade Glioma Stem Cells

Both in adult and children, high-grade gliomas (WHO grades III and IV) account for a high proportion of death due to cancer. This poor prognosis is a direct consequence of tumor recurrences occurring within few months despite a multimodal therapy consisting of a surgical resection followed by chemotherapy and radiotherapy. There is increasing evidence that glioma stem cells (GSCs) contribute to tumor recurrences. In fact, GSCs can migrate out of the tumor mass and reach the subventricular zone (SVZ), a neurogenic niche persisting after birth. Once nested in the SVZ, GSCs can escape a surgical intervention and resist to treatments. The present review will define GSCs and describe their similarities with neural stem cells, residents of the SVZ. The architectural organization of the SVZ will be described both for humans and rodents. The migratory routes taken by GSCs to reach the SVZ and the signaling pathways involved in their migration will also be described hereafter. In addition, we will debate the advantages of the microenvironment provided by the SVZ for GSCs and how this could contribute to tumor recurrences. Finally, we will discuss the clinical relevance of the SVZ in adult GBM and pediatric HGG and the therapeutic advantages of targeting that neurogenic region in both clinical situations

Comprehensive profiling of stem-like features in pediatric glioma cell cultures and their relation to the subventricular zone

peer reviewe

The expression of B7-H3 isoforms in newly diagnosed glioblastoma and recurrence and their functional role.

Short survival of glioblastoma (GBM) patients is due to systematic tumor recurrence. Our laboratory identified a GBM cell subpopulation able to leave the tumor mass (TM) and invade the subventricular zone (SVZ-GBM cells). SVZ-GBM cells escape treatment and appear to contribute to GBM recurrence. This study aims to identify proteins specifically expressed by SVZ-GBM cells and to define their role(s) in GBM aggressiveness and recurrence. The proteome was compared between GBM cells located in the initial TM and SVZ-GBM cells using mass spectrometry. Among differentially expressed proteins, we confirmed B7-H3 by western blot (WB) and quantitative RT-PCR. B7-H3 expression was compared by immunohistochemistry and WB (including expression of its isoforms) between human GBM (N = 14) and non-cancerous brain tissue (N = 8), as well as newly diagnosed GBM and patient-matched recurrences (N = 11). Finally, the expression of B7-H3 was modulated with short hairpin RNA and/or over-expression vectors to determine its functional role in GBM using in vitro assays and a xenograft mouse model of GBM. B7-H3 was a marker for SVZ-GBM cells. It was also increased in human GBM pericytes, myeloid cells and neoplastic cells. B7-H3 inhibition in GBM cells reduced their tumorigenicity. Out of the two B7-H3 isoforms, only 2IgB7-H3 was detected in non-cancerous brain tissue, whereas 4IgB7-H3 was specific for GBM. 2IgB7-H3 expression was higher in GBM recurrences and increased resistance to temozolomide-mediated apoptosis. To conclude, 4IgB7-H3 is an interesting candidate for GBM targeted therapies, while 2IgB7-H3 could be involved in recurrence through resistance to chemotherapy