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Prior Activation (prior + activation)
Selected AbstractsGroup III metabotropic glutamate receptor activation suppresses self-replication of undifferentiated neocortical progenitor cellsJOURNAL OF NEUROCHEMISTRY, Issue 5 2008Noritaka Nakamichi§ Abstract We evaluated the possible functional expression of metabotropic glutamate receptors (mGluRs) by neural progenitors from embryonic mouse neocortex. Constitutive expression was seen with group I, II, and III mGluRs in undifferentiated cells and neurospheres formed by clustered cells during culture with epidermal growth factor. The group III mGluR agonist, l -2-amino-4-phosphonobutyrate, drastically reduced proliferation activity at 1,100 ,M without inducing cell death, with group I and group II mGluR agonists being ineffective, in these neurospheres. Both forskolin and a group III mGluR antagonist significantly increased the proliferation alone, but significantly prevented the suppression by l -2-amino-4-phosphonobutyrate. Activation of group III mGluR significantly decreased mRNA expression of the cell cycle regulator cyclinD1, in addition to inhibiting the transactivation mediated by cAMP of cyclinD1 gene in the pluripotent P19 progenitor cells. Prior activation of group III mGluR led to a significant decrease in the number of cells immunoreactive for a neuronal marker, with an increase in that for an astroglial marker irrespective of differentiation inducers. These results suggest that group III mGluR may be functionally expressed to suppress self-renewal capacity through a mechanism related to cAMP formation with promotion of subsequent differentiation into astroglial lineage in neural progenitors. [source] Killers and beyond: NK-cell-mediated control of immune responsesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2008Christopher E. Andoniou Abstract Effective immunity requires coordinated activation of innate and adaptive immune responses. NK cells are principal mediators of innate immunity, able to respond to challenge quickly and generally without prior activation. The most acknowledged functions of NK cells are their cytotoxic potential and their ability to release large amounts of cytokines, especially IFN-,. Recently, it has become clear that NK cells are more than assassins. Indeed, NK cells play critical roles in shaping adaptive immunity. [source] Cell proliferation and apoptosis: dual-signal hypothesis tested in tuberculous pleuritis using mycobacterial antigensFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2004Sulochana D. Das Abstract Antigens and mitogens have the innate ability to trigger cell proliferation and apoptosis thus exhibiting a dual-signal phenomenon. This dual-signal hypothesis was tested with mycobacterial antigens (PPD and heat killed Mycobacterium tuberculosis, MTB) in tuberculous pleuritis patients where the immune response is protective and compartmentalized. We compared and correlated the cell-cycle analysis and antigen-induced apoptosis in normal and patients' peripheral blood mononuclear cells (PBMCs) and patients' pleural fluid mononuclear cells (PFMCs). In cell-cycle analysis, PFMCs showed good mitotic response with PPD and MTB antigens where 10% and 7% of resting cells entered the S and G2/M phases of cell cycle, respectively. This antigen-induced proliferation of PFMCs correlated well with the lymphocyte transformation test (LTT) results. On the other hand, PFMCs also showed 21% of spontaneous apoptosis, which further increased to 43%, by induction with known apoptotic agent like Dexamethasone (DEX) and the mycobacterial antigens PPD and MTB. Further we demonstrated by anti-CD3 induction experiments that prior activation of cells is prerequisite for them to undergo apoptosis. Our results showed that PPD and MTB antigens induced both cell proliferation and apoptosis in PFMCs, which were pre-sensitized to mycobacterial antigens in vivo. Thus the dual-signal phenomenon was operative against these antigens in tuberculous pleuritis. We also demonstrated that the activated cells are more predisposed to apoptosis. [source] Polymer-bound alkyltriazenes for mild racemization-free esterification of amino acid and peptide derivativesJOURNAL OF PEPTIDE SCIENCE, Issue 10 2004Joachim Smerdka Abstract A novel tool for polymer-assisted solution phase (PASP) esterification of amino acid and peptide derivatives has been developed. When treated with carboxylic acids, polymer-bound alkyltriazenes react with a loss of nitrogen and transfer of the alkyl moiety to the carboxylate anion to form the corresponding alkyl esters. There are no limitations with regard to either the protecting groups or the nature of the amino acid. Furthermore no racemization occurs at the chiral centers of the amino acids as demonstrated by chiral GC-MS analyses. Alkyltriazene-resins were also applied successfully to the esterification of peptide acids and other peptidic structures, such as tripalmitoyl- S -glyceryl-cysteine (Pam3Cys). The triazene-mediated esterification reaction is exceptionally mild, and there is no need for prior activation of the carboxy groups. This method is therefore particularly suitable for the alkylation of complex peptidomimetic structures prone to racemization and for acid-sensitive structures. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd. [source] | ||||||||||