GliomaBrain NeoplasmsGlioblastomaAstrocytomaOptic Nerve GliomaBrain Stem NeoplasmsCell Line, TumorDacarbazineTumor Cells, CulturedAntineoplastic Agents, AlkylatingNeoplasm GradingSupratentorial NeoplasmsMice, NudeTreatment OutcomeNeoplasm TransplantationNeoplasm InvasivenessGene Expression Regulation, NeoplasticGliosarcomaIsocitrate DehydrogenaseCell ProliferationMagnetic Resonance ImagingAntineoplastic AgentsNimustineApoptosisCentral Nervous System NeoplasmsMeningiomaXenograft Model Antitumor Assays