Defining secretion processes in astrocytes

During the last decade, evidence that release of chemical transmitters from astrocytes might modulate neuronal activity (the so-called "gliotransmission") occurs in situ has been extensively provided. Nevertheless, gliotransmission remains a highly debated topic because of the lack of direct morphological and functional evidence. Here we provided new information supporting gliotransmission, by i) deepen knowledge about specific properties of regulated secretion of glutamatergic SLMVs, and ii) investigating the involvement of astrocytes in the transmission of dopamine, a molecule whose interaction with astrocytes is likely to occur, but it's still not proven.¦VGLUT-expressing glutamatergic SLMVs have been previously identified both in situ and in vitro, but description of kinetics of release were still lacking. To elucidate this issue, we took advantage of fluorescent tools (styryl dyes and pHluorin) and adapted experimental paradigms and analysis methods previously developed to study exo-endocytosis and recycling of glutamatergic vesicles at synapses. Parallel use of EPIfluorescence and total internal reflection (TIRF) imaging allowed us to find that exo-endocytosis processes in astrocytes are extremely fast, with kinetics in the order of milliseconds, able to sustain and follow neuronal signalling at synapses. Also, exocytosis of SLMVs is under the control of fast, localized Ca2+ elevations in close proximity of SLMVs and endoplasmatic reticulum (ER) tubules, the intracellular calcium stores. Such complex organization supports the fast stimulus-secretion coupling we described; localized calcium elevations have been recently observed in astrocytes in situ, suggesting that these functional microdomains might be present in the intact tissue. In the second part of the work, we investigated whether astrocytes possess some of the benchmarks of brain dopaminergic cells. It's been known for years that astrocytes are able to metabolize monoamines by the enzymes MAO and COMT, but to date no clear information that glial cells are able to uptake and store monoamines have been provided. Here, we identified a whole apparatus for the storage, degradation and release of monoamines, at the ultrastructural level. Electron microscopy immunohistochemistry allowed us to visualize VMAT2- and dopamine-positive intracellular compartments within astrocytic processes, i.e. dense -core granules and cisterns. These organelles might be responsible for dopamine release and storage, respectively; interestingly, this intracellular distribution is reminiscent of VMAT2 expression in dendrites if neurons, where dopamine release is tonic and plays a role in the regulation of its a basal levels, suggesting that astrocytic VMAT2 is involved in the homeostasis of dopamine in healthy brains of adult mammals.¦Durant cette dernière décennie, de nombreux résultats sur le relâchement des transmetteurs par les astrocytes pouvant modulé l'activité synaptique (gliotransmission) ont été fournis. Néanmoins, la gliotransmission reste un processus encore très débattu, notamment à cause de l'absence de preuves directes, morphologique et fonctionnelle démontrant ce phénomène. Nous présentons dans nos travaux de nombreux résultats confortant l'hypothèse de la gliotransmission, dont i) une étude approfondie sur les propriétés spatiales et temporelles de la sécrétion régulée du glutamate dans les astrocytes, et ii) une étude sur la participation des astrocytes dans la transmission de la dopamine, une neuromodulateur dont l'interaction avec les astrocytes est fortement probable, mais qui n'a encore jamais été prouvée. L'expression des petites vésicules (SLMVs - Synaptic Like Micro Vesicles) glutamatergiques exprimant les transporteurs vésiculaires du glutamate (VGLUTs) dans les astrocytes a déjà été prouvé tant in situ qu'in vitro. Afin de mettre en évidence les propriétés précises de la sécrétion de ces organelles, nous avons adapté à nos études des méthodes expérimentales conçues pour observer les processus de exocytose et endocytose dans les neurones. Les résolutions spatiale et temporelle obtenues, grâce a l'utilisation en parallèle de l'épi fluorescence et de la fluorescence a onde évanescente (TIRF), nous ont permis de montrer que la sécrétion régulée dans les astrocytes est un processus extrêmement rapide (de l'ordre de la milliseconde) et qu'elle est capable de soutenir et de suivre la transmission de signaux entre neurones. Nous avons également découvert que cette sécrétion a lieu dans des compartiments subcellulaires particuliers où nous observons la présence du reticulum endoplasmique (ER) ainsi que des augmentations rapides de calcium. Cette organisation spatiale complexe pourrait être la base morphologique du couplage rapide entre le stimulus et la sécrétion. Par ailleurs, plusieurs études récentes in vivo semblent confirmer l'existence de ces compartiments. Depuis des années nous savons que les astrocytes sont capables de métaboliser les monoamines par les enzymes MAO et COMT. Nous avons donc fourni de nouvelles preuves concernant la présence d'un appareil de stockage dans les astrocytes participant à la dégradation et la libération de monoamines au niveau ultrastructurelle. Grâce à la microscopie électronique, nous avons découvert la présence de compartiments intracellulaires exprimant VMAT2 dans les processus astrocytaires, sous forme de granules et des citernes. Ces organelles pourraient donc être responsables à la fois du relâchement et du stockage de la dopamine. De manière surprenante, cette distribution intracellulaire est similaire aux dendrites des neurones exprimant VMAT2, où la dopamine est libérée de façon tonique permettant d'agir sur la régulation de ses niveaux de base. Ces résultats, suggèrent une certaine participation des VMAT2 présents dans les astrocytes dans le processus d'homéostase de la dopamine dans le cerveau.¦A de nombreuses reprises, dans des émissions scientifiques ou dans des films, il est avancé que les hommes n'utilisent que 10% du potentiel de leur cerveau. Cette légende provient probablement du fait que les premiers chercheurs ayant décrit les cellules du cerveau entre le XIXème et le XXeme siècle, ont montré que les neurones, les cellules les plus connues et étudiées de cet organe, ne représentent seulement que 10% de la totalité des cellules composant du cerveau. Parmi les 90% restantes, les astrocytes sont sans doute les plus nombreuses. Jusqu'au début des années 90, les astrocytes ont été plutôt considérés peu plus que du tissu conjonctif, ayant comme rôles principaux de maintenir certaines propriétés physiques du cerveau et de fournir un support métabolique (énergie, environnement propre) aux neurones. Grace à la découverte que les astrocytes ont la capacité de relâcher des substances neuro-actives, notamment le glutamate, le rôle des astrocytes dans le fonctionnement cérébral a été récemment reconsidérée.¦Le rôle du glutamate provenant des astrocytes et son impact sur la fonctionnalité des neurones n'a pas encore été totalement élucidé, malgré les nombreuses publications démontrant l'importance de ce phénomène en relation avec différentes fonctions cérébrales. Afin de mieux comprendre comment les astrocytes sont impliqués dans la transmission cérébrale, nous avons étudié les propriétés spatio-temporelles de cette libération grâce à l'utilisation des plusieurs marqueurs fluorescents combinée avec différentes techniques d'imagerie cellulaires. Nous avons découvert que la libération du glutamate par les astrocytes (un processus maintenant appelé "gliotransmission") était très rapide et contrôlée par des augmentations locales de calcium. Nous avons relié ces phénomènes à des domaines fonctionnels subcellulaires morphologiquement adaptés pour ce type de transmission. Plus récemment, nous avons concentré nos études sur un autre transmetteur très important dans le fonctionnement du cerveau : la dopamine. Nos résultats morphologiques semblent indiquer que les astrocytes ont la capacité d'interagir avec ce transmetteur, mais d'une manière différente comparée au glutamate, notamment en terme de rapidité de transmission. Ces résultats suggèrent que le astrocytes ont la capacité de modifier leurs caractéristiques et de s'adapter à leur environnement par rapport aux types de transmetteur avec lequel ils doivent interagir.

Youth of the Eighties, Parents of 2000, Sociological Observations

(Résumé de l'ouvrage) This book is meant to honour the Belgian religious educationalist Herman Lombaerts reflecting on his legacy. He is internationally renowned as a scholar with a strong commitment to and a conceptual analysis of the social and cultural context in which people live and learn. This series of essays is build upon a thought provoking, streamlined design on the relationship between theology and education, relying on Lombaerts' societal and cultural analysis of contemporary religious education. Three key elements are at stake: the self-agency of the learner, the hermeneutic and communitive interpretation of religious traditions in the teaching of religion, and the radical re-imagination of Christian theology relying on this new model of religious educational praxis. For Lombaerts, the search processes of religious people have their own dynamic and dignity. Practical theology should listen carefully and empathetically to this quest. But he is also convinced of the need of solid fundamental research to understand critically its ambiguities and perspectives. Scholars from Europe, the United States and Australia lead the way in this process of "conceptual stretching". Issues such as happiness of children, identity formation of youth, educational and religious insecurity of parents, multi-faith education, tradition crisis of churches, theological education of lay ministers, narrativity and modern art in religious education, etc. are examined from a practical theological point of view, with a strong commitment to the philosophical, psychological, sociological, educational and political dimensions of three issues. With this book the editors hope to commemorate Lombaerts' international radiation, by building a collegial bridge between the different theoretical approaches in the German, Dutch, French, Italian and Anglo-Saxon religious educational research.

Language and syntactic impairment following stroke in late bilingual aphasics.

PURPOSE: Bilingual aphasia generally affects both languages. However, the age of acquisition of the second language (L2) seems to play a role in the anatomo-functional correlation of the syntactical/grammatical processes, thus potentially influencing the L2 syntactic impairment following a stroke. The present study aims to analyze the influence of late age of acquisition of the L2 on syntactic impairment in bilingual aphasic patients. METHODS: Twelve late bilingual participants (speaking French as L2 and either English, German, Italian or Spanish as L1) with stroke-induced aphasia participated in the study. The MAST or BAT aphasia batteries were used to evaluate overall aphasia score. An auditory syntactic judgement task was developed and used to test participants syntactic performance. RESULTS: The overall aphasia scores did not differ between L1 and L2. In a multiple case analysis, only one patient had lower scores in L2. However, four patients presented significantly lower performances in syntactic processing in the late L2 than in their native language (L1). In these four patients the infarct was localized, either exclusively or at least partially, in the pre-rolandic region. CONCLUSION: This pilot study suggests that, in late bilingual aphasics, syntactic judgment abilities may be more severely impaired in L2, and that this syntactic deficit is most likely to occur following anterior lesions.

Spirituality and religious practices among outpatients with schizophrenia and their clinicians

OBJECTIVES: Religious issues may be neglected by clinicians who are treating psychotic patients, even when religion constitutes an important means of coping. This study examined the spirituality and religious practices of outpatients with schizophrenia compared with their clinicians. Clinicians' knowledge of patients' religious involvement and spirituality was investigated. METHODS: The study sample included 100 patients of public psychiatric outpatient facilities in Geneva, Switzerland, with a diagnosis of nonaffective psychosis. Audiotaped interviews were conducted with use of a semistructured interview about spirituality and religious coping. The patients' clinicians (N=34) were asked about their own beliefs and religious activities as well as their patients' religious and clinical characteristics. RESULTS: Sixteen patients (16 percent) had positive psychotic symptoms reflecting aspects of their religious beliefs. A majority of the patients reported that religion was an important aspect of their lives, but only 36 percent of them had raised this issue with their clinicians. Fewer clinicians were religiously involved, and, in half the cases, their perceptions of patients' religious involvement were inaccurate. A few patients considered religious practice to be incompatible with treatment, and clinicians were seldom aware of such a conflict. CONCLUSIONS: Religion is an important issue for patients with schizophrenia, and it is often not related to the content of their delusions. Clinicians were commonly not aware of their patients' religious involvement, even if they reported feeling comfortable with such an issue.

Arrested kinetic Li isotope fractionation at the margin of the llimaussaq complex, South Greenland: Evidence for open-system processes during final cooling of peralkaline igneous rocks

Li contents [Li] and isotopic composition (delta Li-7) of mafic minerals (mainly amphibole and clinopyroxene) from the alkaline to peralkaline Ilimaussaq plutonic complex, South Greenland, track the behavior of Li and its isotopes during magmatic differentiation and final cooling of an alkaline igneous system. [Li] in amphibole increase from < 10 ppm in Caamphiboles of the least differentiated unit to >3000 ppm in Na-amphiboles of the highly evolved units. In contrast, [Li] in clinopyroxene are comparatively low (<85 ppm) and do not vary systematically with differentiation. The distribution of Li between amphibole and pyroxene is controlled by the major element composition of the minerals (Ca-rich and Na-rich, respectively) and changes in oxygen fugacity (due to Li incorporation via coupled substitution with ferric iron) during magmatic differentiation. delta(7) Li values of all minerals span a wide range from + 17 to - 8 parts per thousand, with the different intrusive units of the complex having distinct Li isotopic systematics. Amphiboles, which dominate the Li budget of whole-rocks from the inner part of the complex, have constant delta Li-7 of + 1.8 +/- 2.2 parts per thousand (2 sigma, n = 15). This value reflects a homogeneous melt reservoir and is consistent with their mantle derivation, in agreement with published O and Nd isotopic data. Clinopyroxenes of these samples are consistently lighter, with Delta Li-7(amph-cpx). as large as 8 parts per thousand and are thus not in Li isotope equilibrium. These low values probably reflect late-stage diffusion of Li into clinopyroxene during final cooling of the rocks, thus enriching the clinopyroxene in 6 Li. At the margin of the complex delta(7) Li in the syenites increases systematically, from +2 to high values of + 14 parts per thousand. This, coupled with the observed Li isotope systematics of the granitic country rocks, reflects post-magmatic open-system processes occurring during final cooling of the intrusion. Although the shape and magnitude of the Li isotope and elemental profiles through syenite and country rock are suggestive of diffusion-driven isotope fractionation, they cannot be modeled by one-dimensional diffusive transport and point to circulation of a fluid having a high 67 Li value (possibly seawater) along the chilled contact. In all, this study demonstrates that Li isotopes can be used to identify complex fluid- and diffusion-governed processes taking place during the final cooling of such rocks. (c) 2007 Elsevier B.V All rights reserved.

Autologous Stem Cell Transplantation (ASCT) for Enteropathy-Associated T-Cell Lymphoma (EATL): Final Analysis of a Retrospective Study On the Behalf of Lymphoma Working Party (LWP) of the European Group for Blood and Marrow Transplantation (EBMT).

Background: EATL is a rare subtype of peripheral T-cell lymphomas characterized by primarily intestinal localization and a frequent association with celiac disease. The prognosis is considered to be poor with conventional chemotherapy. Limited data is available on the efficacy of ASCT in this lymphoma subtype. Primary objective: was to study the outcome of ASCT as a consolidation or salvage strategy for EATL. The primary endpoint was overall survival (OS) and progression-free survival (PFS). Eligible patients were > 18 years who had received ASCT between 2000-2010 for EATL that was confirmed by review of written histopathology reports, and had sufficient information on disease history and follow-up available. The search strategy used the EBMT database to identify patients potentially fulfilling the eligibility criteria. An additional questionnaire was sent to individual transplant centres to confirm histological diagnosis (histopathology report or pathology review) as well as updated follow-up data. Patients and transplant characteristics were compared between groups using X2 test or Fisher's exact test for categorical variables and t-test or Mann-Whiney U-test for continuous variables. OS and PFS were estimated using the Kaplan-Meier product-limit estimate and compared by the log-rank test. Estimates for non-relapse mortality (NRM) and relapse or progression were calculated using cumulative incidence rates to accommodate competing risk and compared to Gray's test. Results: Altogether 138 patients were identified. Updated follow-up data was received from 74 patients (54 %) and histology report from 54 patients (39 %). In ten patients the diagnosis of EATL could not be adequately verified. Thus the final analysis included 44. There were 24 males and 20 females with a median age of 56 (35-72) years at the time of transplant. Twenty-five patients (57 %) had a history of celiac disease. Disease stage was I in nine patients (21 %), II in 14 patients (33 %) and IV in 19 patients (45 %). Twenty-four patients (55 %) were in the first CR or PR at the time of transplant. BEAM was used as a high-dose regimen in 36 patients (82 %) and all patients received peripheral blood grafts. The median follow-up for survivors was 46 (2-108) months from ASCT. Three patients died early from transplant-related reasons translating into a 2-year non-relapse mortality of 7 %. Relapse incidence at 4 years after ASCT was 39 %, with no events occurring beyond 2.5 years after ASCT. PFS and OS were 54 % and 59 % at four years, respectively. There was a trend for better OS in patients transplanted in the first CR or PR compared to more advanced disease status (70 % vs. 43 %, p=0.053). Of note, patients with a history of celiac disease had superior PFS (70 % vs. 35 %, p=0.02) and OS (70 % vs. 45 %, p=0.052) whilst age, gender, disease stage, B-symptoms at diagnosis or high-dose regimen were not associated with OS or PFS. Conclusions: This study shows for the first time in a larger patient sample that ASCT is feasible in selected patients with EATL and can yield durable disease control in a significant proportion of the patients. Patients transplanted in first CR or PR appear to do better than those transplanted later. ASCT should be considered in EATL patients responding to initial therapy.