Cyclosporin safety in a simplified rat brain tumor implantation model.

Brain cancer is the second neurological cause of death. A simplified animal brain tumor model using W256 (carcinoma 256, Walker) cell line was developed to permit the testing of novel treatment modalities. Wistar rats had a cell tumor solution inoculated stereotactically in the basal ganglia (right subfrontal caudate). This model yielded tumor growth in 95% of the animals, and showed absence of extracranial metastasis and systemic infection. Survival median was 10 days. Estimated tumor volume was 17.08 ± 6.7 mm(3) on the 7(th) day and 67.25 ± 19.8 mm(3) on 9(th) day post-inoculation. Doubling time was 24.25 h. Tumor growth induced cachexia, but no hematological or biochemical alterations. This model behaved as an undifferentiated tumor and can be promising for studying tumor cell migration in the central nervous system. Dexamethasone 3.0 mg/kg/day diminished significantly survival in this model. Cyclosporine 10 mg/kg/day administration was safely tolerated.

Cyclosporin safety in a simplified rat brain tumor implantation model / Segurança do tratamento com ciclosporina em um modelo pré-clínico de tumor cerebral experimental em ratos

Brain cancer is the second neurological cause of death. A simplified animal brain tumor model using W256 (carcinoma 256, Walker) cell line was developed to permit the testing of novel treatment modalities. Wistar rats had a cell tumor solution inoculated stereotactically in the basal ganglia (right subfrontal caudate). This model yielded tumor growth in 95 percent of the animals, and showed absence of extracranial metastasis and systemic infection. Survival median was 10 days. Estimated tumor volume was 17.08±6.7 mm³ on the 7th day and 67.25±19.8 mm³ on 9th day post-inoculation. Doubling time was 24.25 h. Tumor growth induced cachexia, but no hematological or biochemical alterations. This model behaved as an undifferentiated tumor and can be promising for studying tumor cell migration in the central nervous system. Dexamethasone 3.0 mg/kg/day diminished significantly survival in this model. Cyclosporine 10 mg/kg/day administration was safely tolerated.

Neoplasias encefálicas constituem a segunda causa neurológica de morte. Foi desenvolvido um modelo animal simplificado de tumor cerebral em ratos utilizando a linhagem celular W256 (carcinoma 256 de Walker) para permitir teste de novos tratamentos. Ratos Wistar foram inoculados nos gânglios da base (caudato subfrontal direito) com uma solução celular tumoral, por via estereotáxica. Este modelo demonstrou crescimento tumoral em 95 por cento dos animais inoculados com sucesso, além de mostrar ausência de metástases extracranianas e infecção sistêmica. A mediana de sobrevida dos animais foi de 10 dias. O volume tumoral estimado foi de 17,08±6,7 mm³ no sétimo dia e de 67,25±19,8 mm³ no nono dia após a inoculação. O tempo de duplicação foi estimado em 24,25 h. O crescimento tumoral induziu a caquexia, mas não houve alterações bioquímicas ou hematológicas. Esse modelo permite fácil reprodução e comporta-se como um tumor indiferenciado, mostrando potencial para estudar migração celular tumoral no sistema nervoso central. Dexametasona 3,0 mg/kg/dia reduziu significantemente a sobrevida dos animais inoculados com tumor nesse modelo. Ciclosporina 10 mg/kg/dia não teve efeito na sobrevida, sendo sua administração bem tolerada.

Renal and vascular effects of the natriuretic peptide isolated from Crotalus durissus cascavella venom.

Crotalus durissus cascavella is a snake that is usually found in the scrublands of northeast Brazil. The components of its venom may have effects on the vascular and renal systems. Recently, a new bradykinin inhibitory peptide has been identified in the venom of the Crotalinae family. The aim of the present study was to investigate the renal and vascular effects of the natriuretic peptide isolated from the venom of Crotalus durissus cascavella (NP2_Casca). The chromatographic profile showed the fractionation of substances identified as convulxin, gyroxin, crotoxin and crotamine, as well as fractions V and VI. The electrophoretic profile of fraction V consisted of several bands ranging from approximately 6kDa to 13kDa, while fraction VI showed only two main electrophoretic bands with molecular weights of approximately 6 and 14kDa. Reverse-phase chromatography showed that NP2_Casca corresponds to about 18% of fraction VI and that this fraction is the main natriuretic peptide. NP2_Casca was compared to other natriuretic peptides from other sources of snake venom. All amino acid sequences that were compared showed a consensus region of XGCFGX, XLDRIX and XSGLGCX. The group treated with NP2_Casca showed an increase in perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. The percent of total and proximal tubular transport of sodium was reduced significantly after administration of the peptide. The mean arterial pressure showed a dose-dependent decrease after infusion of NP2_Casca, and an increase in nitrite production. In the aortic ring assay, NP2_Casca caused a relaxant effect in endothelium-intact thoracic aortic rings precontracted with phenylephrine in the presence and absence of isatin. NP2_Casca failed to relax the aortic rings precontracted with an isosmotic potassium Krebs-Henseleit solution. In conclusion, the natriuretic peptide isolated from Crotalus durissus cascavella venom produced renal and vascular effects. NP2_Casca reduced total and proximal sodium tubular transport, leading to an increase in sodium excretion, thereby demonstrating a diuretic action. A hypotensive effect was displayed in an arterial pressure assay, with an increase in nitrite production, suggesting a possible vasoactive action.