Charles Félix Calvo

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Brain inflammation is characterized by a reactive gliosis involving the activation of astrocytes and microglia. This process, common to many brain injuries and diseases, underlies important phenotypic changes in these two glial cell types. One characteristic feature of astrocytes is their high level of intercellular communication mediated by gap junctions.(More)
Astrocytes express high levels of connexin43, a protein that forms two types of channels: gap junction channels for direct intercellular communication, and hemichannels for exchanges with the extracellular space. Inflammation induces connexin43 hemichannel activation, which has been proposed to be involved in neuroglial interactions. Here, we investigated(More)
Neural stem cells (NSCs) are slowly dividing astrocytes that are intimately associated with capillary endothelial cells in the subventricular zone (SVZ) of the brain. Functionally, members of the vascular endothelial growth factor (VEGF) family can stimulate neurogenesis as well as angiogenesis, but it has been unclear whether they act directly via VEGF(More)
Jurkat and HUT 78 T cell lines, as well as peripheral blood human T cells activated with PHA plus PMA were used to investigate the capacity of substance P (SP) neuropeptide to regulate IL-2 production. By using Northern blot analysis and dosage of the IL-2 release in cell supernatants, we show that SP can act as cosignal with PHA + PMA to enhance the(More)
Background: ASPM (Abnormal Spindle-like Microcephaly associated) over-expression was recently implicated in the development of malignant gliomas. Results: To better characterize the involvement of ASPM in gliomas, we investigated the mRNA expression in 175 samples, including 8 WHO Grade II, 75 WHO Grade III and 92 WHO Grade IV tumors. Aspm expression was(More)
Gene expression studies require a sensitive and quantitative assay of mRNA amounts present in small samples. We describe a general method of quantifying specific mRNA quickly and easily from purified RNA or directly from a few cells by PCR and enzyme-linked immunosorbent assay (ELISA) revelation of the resulting products (sensitivity of the last step: < 0.1(More)
Cultured astrocytes are highly coupled by gap junction channels mainly constituted by connexin 43. We have previously shown that gap junctional communication (GJC) represents a functional property of astrocytes that is a target for their interaction with other brain cell types, including neurons and brain macrophages. In pathological situations, neurons as(More)
Conditioned media from embryonic mixed cells from the rat brain were used in a chemotaxis assay to look for potential chemotactic activity which could account for the infiltration of the developing central nervous system (CNS) by macrophage precursors. The most potent chemotactic activity was found in the conditioned medium from E17 mixed brain cells(More)
Fifteen patients and their respective bone marrow donors were entered in this study 1 to 5 yr after allogeneic bone marrow transplantation. Peripheral blood E rosetting (T) cells were analyzed for their phenotypic characteristics as well as for their ability to regulate Ig synthesis in the in vitro PWM system. A close relationship was found between a high(More)
Fc gamma receptor-bearing U937 cells, when incubated in serum-free buffer, were found to release spontaneously a suppressor material for pokeweed mitogen-drigen IgG synthesis which could be retained on Sepharose 4B-IgG immunosorbents. Immunosorbents coupled with IgM or F (ab')2 fragments of IgG were unable to retain the inhibitory activity of U937-derived(More)