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Marcel B Bally - One of the best experts on this subject based on the ideXlab platform.
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a novel liposomal irinotecan formulation with significant anti tumour activity use of the divalent cation ionophore A23187 and copper containing liposomes to improve drug retention
European Journal of Pharmaceutics and Biopharmaceutics, 2008Co-Authors: Euan Ramsay, Jehan Alnajim, Malathi Anantha, Jason Zastre, Murray S Webb, Dawn Waterhouse, Marcel B BallyAbstract:We determined whether the method used to encapsulate irinotecan into 1,2-distearoyl-sn-glycero-phosphocholine/cholesterol (DSPC/Chol; 55:45 mol%) liposomes influenced: (i) irinotecan release rate and (ii) therapeutic efficacy. DSPC/Chol (55:45 mol%) liposomes were prepared with: (i) unbuffered CuSO4; (ii) buffered (pH 7.5) CuSO4; (iii) unbuffered MnSO4 and the ionophore A23187 (exchanges internal metal2+ with external 2H+ to establish and maintain a transmembrane pH gradient); and (iv) unbuffered CuSO4 and ionophore A23187. All formulations exhibited >98% irinotecan encapsulation (0.2 drug-to-lipid molar ratio; 10 min incubation at 50 °C). Following a single intravenous injection (100 mg/kg irinotecan) into Balb/c mice, the unbuffered CuSO4 plus A23187 formulation mediated a half-life of irinotecan release of 44.4 h; a 4-fold increase compared to the other liposome formulations. This surprising observation demonstrated that the CuSO4 plus A23187 formulation enhanced irinotecan retention compared to the MnSO4 plus A23187 formulation, indicating the importance of the divalent metal. A single dose of the CuSO4 plus A23187 formulation (50 mg/kg irinotecan) mediated an 18-fold increase in median T − C (the difference in days for treated and control subcutaneous human LS 180 adenocarcinoma xenografts to increase their initial volume by 400%) when compared to a comparable dose of Camptosar®. Improved irinotecan retention was associated with increased therapeutic activity.
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a novel liposomal irinotecan formulation with significant anti tumour activity use of the divalent cation ionophore A23187 and copper containing liposomes to improve drug retention
European Journal of Pharmaceutics and Biopharmaceutics, 2008Co-Authors: Euan Ramsay, Jehan Alnajim, Malathi Anantha, Jason Zastre, Murray S Webb, Dawn Waterhouse, Marcel B Bally, Hong YanAbstract:We determined whether the method used to encapsulate irinotecan into 1,2-distearoyl-sn-glycero-phosphocholine/cholesterol (DSPC/Chol; 55:45 mol%) liposomes influenced: (i) irinotecan release rate and (ii) therapeutic efficacy. DSPC/Chol (55:45 mol%) liposomes were prepared with: (i) unbuffered CuSO4; (ii) buffered (pH 7.5) CuSO4; (iii) unbuffered MnSO4 and the ionophore A23187 (exchanges internal metal2+ with external 2H+ to establish and maintain a transmembrane pH gradient); and (iv) unbuffered CuSO4 and ionophore A23187. All formulations exhibited >98% irinotecan encapsulation (0.2 drug-to-lipid molar ratio; 10 min incubation at 50 degrees C). Following a single intravenous injection (100mg/kg irinotecan) into Balb/c mice, the unbuffered CuSO4 plus A23187 formulation mediated a half-life of irinotecan release of 44.4h; a >or=4-fold increase compared to the other liposome formulations. This surprising observation demonstrated that the CuSO4 plus A23187 formulation enhanced irinotecan retention compared to the MnSO4 plus A23187 formulation, indicating the importance of the divalent metal. A single dose of the CuSO4 plus A23187 formulation (50mg/kg irinotecan) mediated an 18-fold increase in median T-C (the difference in days for treated and control subcutaneous human LS 180 adenocarcinoma xenografts to increase their initial volume by 400%) when compared to a comparable dose of Camptosar. Improved irinotecan retention was associated with increased therapeutic activity.
J. A. Van Hilten - One of the best experts on this subject based on the ideXlab platform.
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The use of the divalent calcium-ionophore A23187 as a biochemical tool in pharmacological and in vitro toxicological studies.
Cell structure and function, 1996Co-Authors: J H Boot, J. A. Van HiltenAbstract:The use of A23187 as a biochemical tool is described. A23187 was used to elucidate the mechanisms of intracellular transport and secretion of N-hydroxylated aniline metabolites in rat hepatocyte primary culture. Results indicate a membrane-bound intracellular transport. Also, A23187 induced macrophages in their anti-tumour cytostatic activity using P815 tumour cells in in vitro co-cultures of macrophages and tumour cells. Results indicate the activating role of A23187 in macrophage leukotriene ?4 release and enhanced macrophage anti-tumour activity. In conclusion, A23187 proved to be a useful tool in studying calcium dependent metabolic processes.
Dawn Waterhouse - One of the best experts on this subject based on the ideXlab platform.
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a novel liposomal irinotecan formulation with significant anti tumour activity use of the divalent cation ionophore A23187 and copper containing liposomes to improve drug retention
European Journal of Pharmaceutics and Biopharmaceutics, 2008Co-Authors: Euan Ramsay, Jehan Alnajim, Malathi Anantha, Jason Zastre, Murray S Webb, Dawn Waterhouse, Marcel B BallyAbstract:We determined whether the method used to encapsulate irinotecan into 1,2-distearoyl-sn-glycero-phosphocholine/cholesterol (DSPC/Chol; 55:45 mol%) liposomes influenced: (i) irinotecan release rate and (ii) therapeutic efficacy. DSPC/Chol (55:45 mol%) liposomes were prepared with: (i) unbuffered CuSO4; (ii) buffered (pH 7.5) CuSO4; (iii) unbuffered MnSO4 and the ionophore A23187 (exchanges internal metal2+ with external 2H+ to establish and maintain a transmembrane pH gradient); and (iv) unbuffered CuSO4 and ionophore A23187. All formulations exhibited >98% irinotecan encapsulation (0.2 drug-to-lipid molar ratio; 10 min incubation at 50 °C). Following a single intravenous injection (100 mg/kg irinotecan) into Balb/c mice, the unbuffered CuSO4 plus A23187 formulation mediated a half-life of irinotecan release of 44.4 h; a 4-fold increase compared to the other liposome formulations. This surprising observation demonstrated that the CuSO4 plus A23187 formulation enhanced irinotecan retention compared to the MnSO4 plus A23187 formulation, indicating the importance of the divalent metal. A single dose of the CuSO4 plus A23187 formulation (50 mg/kg irinotecan) mediated an 18-fold increase in median T − C (the difference in days for treated and control subcutaneous human LS 180 adenocarcinoma xenografts to increase their initial volume by 400%) when compared to a comparable dose of Camptosar®. Improved irinotecan retention was associated with increased therapeutic activity.
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a novel liposomal irinotecan formulation with significant anti tumour activity use of the divalent cation ionophore A23187 and copper containing liposomes to improve drug retention
European Journal of Pharmaceutics and Biopharmaceutics, 2008Co-Authors: Euan Ramsay, Jehan Alnajim, Malathi Anantha, Jason Zastre, Murray S Webb, Dawn Waterhouse, Marcel B Bally, Hong YanAbstract:We determined whether the method used to encapsulate irinotecan into 1,2-distearoyl-sn-glycero-phosphocholine/cholesterol (DSPC/Chol; 55:45 mol%) liposomes influenced: (i) irinotecan release rate and (ii) therapeutic efficacy. DSPC/Chol (55:45 mol%) liposomes were prepared with: (i) unbuffered CuSO4; (ii) buffered (pH 7.5) CuSO4; (iii) unbuffered MnSO4 and the ionophore A23187 (exchanges internal metal2+ with external 2H+ to establish and maintain a transmembrane pH gradient); and (iv) unbuffered CuSO4 and ionophore A23187. All formulations exhibited >98% irinotecan encapsulation (0.2 drug-to-lipid molar ratio; 10 min incubation at 50 degrees C). Following a single intravenous injection (100mg/kg irinotecan) into Balb/c mice, the unbuffered CuSO4 plus A23187 formulation mediated a half-life of irinotecan release of 44.4h; a >or=4-fold increase compared to the other liposome formulations. This surprising observation demonstrated that the CuSO4 plus A23187 formulation enhanced irinotecan retention compared to the MnSO4 plus A23187 formulation, indicating the importance of the divalent metal. A single dose of the CuSO4 plus A23187 formulation (50mg/kg irinotecan) mediated an 18-fold increase in median T-C (the difference in days for treated and control subcutaneous human LS 180 adenocarcinoma xenografts to increase their initial volume by 400%) when compared to a comparable dose of Camptosar. Improved irinotecan retention was associated with increased therapeutic activity.
Naomasa Miki - One of the best experts on this subject based on the ideXlab platform.
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the accumulation of arc an immediate early gene mrna by the inhibition of protein synthesis
Journal of Pharmacological Sciences, 2003Co-Authors: Hisashi Ichikawa, Takahiro Fujimoto, Eiichi Taira, Naomasa MikiAbstract:Arc (activity-regulated cytoskeleton-associated protein) gene is one of the neuron-specific immediate early genes induced by neural activity. The regulation of Arc gene expression is unknown. We found that Arc mRNA is expressed constitutively in L929 cells, a mouse fibroblast cell line, and was, not transiently, increased by the calcium ionophore A23187. To address the induction of Arc mRNA by A23187, we isolated the mouse Arc gene and found that it consists of three exons, with the first exon including the whole coding region. We then constructed luciferase reporters fused with various 5' flanking regions of the mouse Arc gene. The reporter activities were not enhanced by A23187 in the tested regions up to about -9500 bp. As it is reported that protein synthesis is inhibited in by A23187, we treated L929 cells with a protein synthesis inhibitor, cycloheximide (CHX). The increase of Arc mRNA was induced by CHX alone in a calcium-independent manner and was comparable to that by A23187. No additive effect of A23187 was observed on the increase by CHX, whereas the additive effect was seen in PC12 cells. These results suggest that the inhibition of protein synthesis is a crucial factor for the accumulation of Arc mRNA in L929 cells.
J H Boot - One of the best experts on this subject based on the ideXlab platform.
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The use of the divalent calcium-ionophore A23187 as a biochemical tool in pharmacological and in vitro toxicological studies.
Cell structure and function, 1996Co-Authors: J H Boot, J. A. Van HiltenAbstract:The use of A23187 as a biochemical tool is described. A23187 was used to elucidate the mechanisms of intracellular transport and secretion of N-hydroxylated aniline metabolites in rat hepatocyte primary culture. Results indicate a membrane-bound intracellular transport. Also, A23187 induced macrophages in their anti-tumour cytostatic activity using P815 tumour cells in in vitro co-cultures of macrophages and tumour cells. Results indicate the activating role of A23187 in macrophage leukotriene ?4 release and enhanced macrophage anti-tumour activity. In conclusion, A23187 proved to be a useful tool in studying calcium dependent metabolic processes.
