RESUMO
Brain tumor-associated cerebral edema arises because tumor capillaries lack normal blood-brain barrier function; vascular permeability factor (VPF, also known as vascular endothelial growth factor, VEGF) is a likely mediator of this phenomenon. Clinically, dexamethasone reduces brain tumor-associated vascular permeability through poorly understood mechanisms. Our goals were to determine if suppression of permeability by dexamethasone might involve inhibition of VPF action or expression, and if dexamethasone effects in this setting are mediated by the glucocorticoid receptor (GR). In two rat models of permeability (peripheral vascular permeability induced by intradermal injection of 9L glioma cell-conditioned medium or purified VPF, and intracerebral vascular permeability induced by implanted 9L glioma), dexamethasone suppressed permeability in a dose-dependent manner. Since 80% of the permeability-inducing activity in 9L-conditioned medium was removed by anti-VPF antibodies, we examined dexamethasone effects of VPF expression in 9L cells. Dexamethasone inhibited FCS- and PDGF-dependent induction of VPF expression. At all levels (intradermal, intracranial, and cell culture), dexamethasone effects were reversed by the GR antagonist mifepristone (RU486). Dexamethasone may decrease brain tumor-associated vascular permeability by two GR-dependent mechanisms: reduction of the response of the vasculature to tumor-derived permeability factors (including VPF), and reduction of VPF expression by tumor cells.
Assuntos
Neoplasias Encefálicas/fisiopatologia , Permeabilidade Capilar , Dexametasona/farmacologia , Animais , Anticorpos Bloqueadores/imunologia , Northern Blotting , Neoplasias Encefálicas/metabolismo , Células Cultivadas , Meios de Cultivo Condicionados , Relação Dose-Resposta a Droga , Fatores de Crescimento Endotelial/biossíntese , Fatores de Crescimento Endotelial/imunologia , Fatores de Crescimento Endotelial/farmacologia , Glioma/metabolismo , Glioma/fisiopatologia , Linfocinas/biossíntese , Linfocinas/imunologia , Linfocinas/farmacologia , Mifepristona/farmacologia , Fator de Crescimento Derivado de Plaquetas/metabolismo , Ratos , Receptores de Glucocorticoides/metabolismo , Fator A de Crescimento do Endotélio Vascular , Fatores de Crescimento do Endotélio VascularRESUMO
A young patient with pleomorphic xanthoastrocytoma (PXA), a usually benign cerebral tumor, had two recurrences in a short time period. The clinical, pathological and neuroradiological features, including PET with [18F]-fluorodeoxyglucose (FDG), are presented. The PET-FDG study revealed the recurrent tumor to be hypermetabolic. The diagnosis was confirmed histopathologically. As the clinical outcome of patients harboring PXA is not easy to predict because of possible recurrence and/or transformation into more aggressive gliomas, we discuss the predictive indicators of more aggressive clinical behavior.
Assuntos
Astrocitoma/diagnóstico por imagem , Neoplasias Encefálicas/diagnóstico por imagem , Desoxiglucose/análogos & derivados , Radioisótopos de Flúor , Recidiva Local de Neoplasia/diagnóstico por imagem , Tomografia Computadorizada de Emissão , Adulto , Fluordesoxiglucose F18 , Humanos , Masculino , PrognósticoAssuntos
Vértebras Cervicais/patologia , Deslocamento do Disco Intervertebral/patologia , Traumatismos da Coluna Vertebral/patologia , Vértebras Cervicais/cirurgia , Humanos , Deslocamento do Disco Intervertebral/complicações , Imageamento por Ressonância Magnética , Compressão da Medula Espinal/etiologia , Compressão da Medula Espinal/cirurgia , Traumatismos da Coluna Vertebral/complicações , Traumatismos da Coluna Vertebral/cirurgiaRESUMO
A case of giant recurrent intra-abdominal desmoid tumor is presented. A history of childbirth, antecedent surgery, multiple episodes of recurrence, resistance to excisional and radiation therapy, represent common features of desmoid tumors. The size of the recurrence (15.4 kg), the intra-abdominal presentation of the tumor, involvement of the chest wall and focal infiltration of the small bowel are unusual features of this case.
