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Michael R. Zalutsky - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and evaluation of 4-[18F]fluoropropoxy-3-Iodobenzylguanidine ([18F]FPOIBG): A novel 18F-labeled analogue of MIBG
Nuclear Medicine and Biology, 2015Co-Authors: Ganesan Vaidyanathan, Darryl Mcdougald, Eftychia Koumarianou, Jaeyeon Choi, Marc Hens, Michael R. ZalutskyAbstract:Introduction Radioiodinated meta-Iodobenzylguanidine (MIBG), a norepinephrine transporter (NET) substrate, has been extensively used as an imaging agent to study the pathophysiology of the heart and for the diagnosis and treatment of neuroendocrine tumors. The goal of this study was to develop an 18F-labeled analogue of MIBG that like MIBG itself could be synthesized in a single radiochemical step. Towards this end, we designed 4-fluoropropoxy-3-Iodobenzylguanidine (FPOIBG).
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Catabolism of 4-fluoro-3-Iodobenzylguanidine and meta-Iodobenzylguanidine by SK-N-SH neuroblastoma cells.
Nuclear Medicine Communications, 2004Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Kevin L. Alston, Philip Welsh, Michael R. ZalutskyAbstract:Background A fluorine substituted derivative of metaIodobenzylguanidine (MIBG), 4-fluoro-3-Iodobenzylguanidine (FIBG), is retained in SK-N-SH human neuroblastoma cells in vitro to a higher degree than the MIBG. Method To investigate whether the higher retention of FIBG is due to differences in the catabolic degradation of the two tracers, in vitro paired-label studies were performed using SK-N-SH cells. Results No detectable amount of benzyl amines, benzoic acids or hippuran derivatives, potential catabolites of these tracers, were seen in either case. Even after 48 h, the cell culture supernatants contained exclusively intact 1 2 5 I-MIBG and 1 2 5 I-FIBG. In contrast, in some cases, HPLC analysis of cell lysates indicated the presence of a very polar compound(s) as the predominant species with smaller quantities of intact tracers. The per cent total radioactivity in the lysate at each time point that was associated with intact 1 2 5 I-FIBG was (average [range]) 25.4% [20.3-30.5], 22.5% [19.3-25.6], and 18.8% [14.3-23.3], at 0h, 24 h and 48 h, respectively. The corresponding values for 1 2 5 I-MIBG were 24.3% [21.0-27.5], 19.1% [11.7-26.5] and 17.4% [14.6-20.1]. No significant amount of activity was associated with high molecular weight species for either halobenzylguanidine, indicating that protein binding was not a major factor.
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Ring-and side-chain-substituted MIBG analogues
Journal of Labelled Compounds and Radiopharmaceuticals, 2001Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Philip Welsh, Sriram Shankar, S. A. Slade, Michael R. ZalutskyAbstract:In our effort to develop an MIBG analogue with optimised targeting capabilites, we have synthesized a number of ring- and side-chain substituted analogues of MIBG and evaluated their lipophilicity, stability in vitro, uptake in SK-N-SH human neuroblastoma cells and tissue distribution in normal mice. Previously, uptake similar to or higher than that for MIBG in canine adrenal medulla and pheochromocytoma patients has been reported for 4-amino-3-Iodobenzylguanidine (pAIBG) and 4-hydroxy-3-Iodobenzylguanidine (HIBG), which are polar substituent-containing MIBG derivatives (1, 2). However, these two compounds have not been evaluated with respect to their uptake in neuroblastoma cells in vitro. The novel compounds developed in this study were evaluated in comparison with HIBG and pAIBG.
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Validation of 4-[fluorine-18]fluoro-3-Iodobenzylguanidine as a positron-emitting analog of MIBG
Journal of nuclear medicine : official publication Society of Nuclear Medicine, 1995Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Michael R. ZalutskyAbstract:This study evaluates the potentialutilItyof 4-[18Fjfluoro-3-iodo benzylguanidrie((‘@FJF1BG) as an MIBGanalog. Methods In vitroassays of tracer bindingwere earned out using the SK N-SHhumanneuroblastomacelllinein a paired-labelformatto compare[1819F1BG dlrecdywfth no-carA±er-edded (meqMlBG. To ascertaln whether E18FIF1BG, like MIBG,is taken up by the uptake-I mechanism,the effects of desipramine,norepineph rine, and carder MIBGand ABG on cell birdng were deter mined.Preincubationwithouabeln and incubationat 4°C was used to evaluatethe energy-dependenceof(1@F1FlBG u@akeby SK-N-SH cells. Thetissue dIstribution of[18FIF1BG inmicewas compared w@ino-earner-added(1eIJMIBG in a paired-label study.Results:Inpaired-label binding studies,thepercentbind ing of [1@I9FIBG to neuroblastoma cells remained constant over a three-logactivIty rangeandthe levelwas somewhathigher thanthatofno-carner-added[1@I)MIBG. Bsrdngwas blockedby desiprarr*ie,norepinephrlne,carder MIBGand FIBG,ouabain and by incubatingat 4°C, suggestingthat [18FIHBG Istaken up by the uptake-i mechanism.Rediationdosimetrycalculations suggestthat higherdoses of [1@FJF1BG, unlike[124IJMIBG, could be administeredto patients.Conclusion: These in vitroand in vflloevaluationsshow that [1°FJABG Is an exceUentanalog of MIBG, suggestingthat 11°FIABG shouldbe furtherevaluatedfor use in PETimagingof neuroendocA±ne tumorsand cardiacab normaildes.
Ganesan Vaidyanathan - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and evaluation of 4-[18F]fluoropropoxy-3-Iodobenzylguanidine ([18F]FPOIBG): A novel 18F-labeled analogue of MIBG
Nuclear Medicine and Biology, 2015Co-Authors: Ganesan Vaidyanathan, Darryl Mcdougald, Eftychia Koumarianou, Jaeyeon Choi, Marc Hens, Michael R. ZalutskyAbstract:Introduction Radioiodinated meta-Iodobenzylguanidine (MIBG), a norepinephrine transporter (NET) substrate, has been extensively used as an imaging agent to study the pathophysiology of the heart and for the diagnosis and treatment of neuroendocrine tumors. The goal of this study was to develop an 18F-labeled analogue of MIBG that like MIBG itself could be synthesized in a single radiochemical step. Towards this end, we designed 4-fluoropropoxy-3-Iodobenzylguanidine (FPOIBG).
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Catabolism of 4-fluoro-3-Iodobenzylguanidine and meta-Iodobenzylguanidine by SK-N-SH neuroblastoma cells.
Nuclear Medicine Communications, 2004Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Kevin L. Alston, Philip Welsh, Michael R. ZalutskyAbstract:Background A fluorine substituted derivative of metaIodobenzylguanidine (MIBG), 4-fluoro-3-Iodobenzylguanidine (FIBG), is retained in SK-N-SH human neuroblastoma cells in vitro to a higher degree than the MIBG. Method To investigate whether the higher retention of FIBG is due to differences in the catabolic degradation of the two tracers, in vitro paired-label studies were performed using SK-N-SH cells. Results No detectable amount of benzyl amines, benzoic acids or hippuran derivatives, potential catabolites of these tracers, were seen in either case. Even after 48 h, the cell culture supernatants contained exclusively intact 1 2 5 I-MIBG and 1 2 5 I-FIBG. In contrast, in some cases, HPLC analysis of cell lysates indicated the presence of a very polar compound(s) as the predominant species with smaller quantities of intact tracers. The per cent total radioactivity in the lysate at each time point that was associated with intact 1 2 5 I-FIBG was (average [range]) 25.4% [20.3-30.5], 22.5% [19.3-25.6], and 18.8% [14.3-23.3], at 0h, 24 h and 48 h, respectively. The corresponding values for 1 2 5 I-MIBG were 24.3% [21.0-27.5], 19.1% [11.7-26.5] and 17.4% [14.6-20.1]. No significant amount of activity was associated with high molecular weight species for either halobenzylguanidine, indicating that protein binding was not a major factor.
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Ring-and side-chain-substituted MIBG analogues
Journal of Labelled Compounds and Radiopharmaceuticals, 2001Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Philip Welsh, Sriram Shankar, S. A. Slade, Michael R. ZalutskyAbstract:In our effort to develop an MIBG analogue with optimised targeting capabilites, we have synthesized a number of ring- and side-chain substituted analogues of MIBG and evaluated their lipophilicity, stability in vitro, uptake in SK-N-SH human neuroblastoma cells and tissue distribution in normal mice. Previously, uptake similar to or higher than that for MIBG in canine adrenal medulla and pheochromocytoma patients has been reported for 4-amino-3-Iodobenzylguanidine (pAIBG) and 4-hydroxy-3-Iodobenzylguanidine (HIBG), which are polar substituent-containing MIBG derivatives (1, 2). However, these two compounds have not been evaluated with respect to their uptake in neuroblastoma cells in vitro. The novel compounds developed in this study were evaluated in comparison with HIBG and pAIBG.
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Validation of 4-[fluorine-18]fluoro-3-Iodobenzylguanidine as a positron-emitting analog of MIBG
Journal of nuclear medicine : official publication Society of Nuclear Medicine, 1995Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Michael R. ZalutskyAbstract:This study evaluates the potentialutilItyof 4-[18Fjfluoro-3-iodo benzylguanidrie((‘@FJF1BG) as an MIBGanalog. Methods In vitroassays of tracer bindingwere earned out using the SK N-SHhumanneuroblastomacelllinein a paired-labelformatto compare[1819F1BG dlrecdywfth no-carA±er-edded (meqMlBG. To ascertaln whether E18FIF1BG, like MIBG,is taken up by the uptake-I mechanism,the effects of desipramine,norepineph rine, and carder MIBGand ABG on cell birdng were deter mined.Preincubationwithouabeln and incubationat 4°C was used to evaluatethe energy-dependenceof(1@F1FlBG u@akeby SK-N-SH cells. Thetissue dIstribution of[18FIF1BG inmicewas compared w@ino-earner-added(1eIJMIBG in a paired-label study.Results:Inpaired-label binding studies,thepercentbind ing of [1@I9FIBG to neuroblastoma cells remained constant over a three-logactivIty rangeandthe levelwas somewhathigher thanthatofno-carner-added[1@I)MIBG. Bsrdngwas blockedby desiprarr*ie,norepinephrlne,carder MIBGand FIBG,ouabain and by incubatingat 4°C, suggestingthat [18FIHBG Istaken up by the uptake-i mechanism.Rediationdosimetrycalculations suggestthat higherdoses of [1@FJF1BG, unlike[124IJMIBG, could be administeredto patients.Conclusion: These in vitroand in vflloevaluationsshow that [1°FJABG Is an exceUentanalog of MIBG, suggestingthat 11°FIABG shouldbe furtherevaluatedfor use in PETimagingof neuroendocA±ne tumorsand cardiacab normaildes.
Mr Zalutsky - One of the best experts on this subject based on the ideXlab platform.
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3-[211At]astato-4-fluorobenzylguanidine: a potential therapeutic agent with prolonged retention by neuroblastoma cells
British Journal of Cancer, 1997Co-Authors: G Vaidyanathan, X-g Zhao, Rh Larsen, Mr ZalutskyAbstract:An analogue of meta-Iodobenzylguanidine (MIBG) in which an aromatic hydrogen was replaced with fluorine has been found to possess many properties similar to those of the parent compound. Moreover, 4-fluoro-3-Iodobenzylguanidine (FIBG) was retained in vitro by human neuroblastoma cells to a much greater extent than MIBG itself. Since alpha-emitters such as 211At could be valuable for the treatment of micrometastatic disease, an FIBG analogue in which the iodine atom is replaced by 211At would be of interest. In this study, we have evaluated the in vitro and in vivo properties of 3-[211At]astato-4-fluorobenzylguanidine ([211At]AFBG). The specific binding of [211At]AFBG to SK-N-SH human neuroblastoma cells remained fairly constant over 2- to 3-log activity range and was similar to that of [131I]MIBG. The uptake of [211At]AFBG by this cell line was reduced by desipramine, ouabain, 4 degrees C incubation, noradrenaline, unlabelled MIBG and FIBG, suggesting that its uptake is specifically mediated through an active uptake-1 mechanism. Over the 16 h period studied, the amount of [211At]AFBG retained was similar to that of [131I]FIBG, whereas the per cent of retained meta-[211At]astatobenzylguanidine ([211At]MABG) was considerably less than that of [131I]FIBG (53% vs 75%; P < 0.05). The IC50 values for the inhibition of uptake of [131I]MIBG, [211At]MABG, [125I]FIBG and [211At]AFBG by unlabelled MIBG were 209, 300, 407 and 661 nM respectively, suggesting that the affinities of these tracers for the noradrenaline transporter in SK-N-SH cells increase in that order. Compared with [211At]MABG, higher uptake of [211At]AFBG was seen in vivo in normal mouse target tissues such as heart and, to a certain extent, in adrenals. That the uptake of [211At]AFBG in these tissues was related to the uptake-1 mechanism was demonstrated by its reduction when mice were pretreated with desipramine. However, the stability of [211At]AFBG towards in vivo dehalogenation was less than that of [211At]MABG, as evidenced by the higher uptake of 211At in thyroid, spleen, lungs and stomach.
Donna J. Affleck - One of the best experts on this subject based on the ideXlab platform.
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Catabolism of 4-fluoro-3-Iodobenzylguanidine and meta-Iodobenzylguanidine by SK-N-SH neuroblastoma cells.
Nuclear Medicine Communications, 2004Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Kevin L. Alston, Philip Welsh, Michael R. ZalutskyAbstract:Background A fluorine substituted derivative of metaIodobenzylguanidine (MIBG), 4-fluoro-3-Iodobenzylguanidine (FIBG), is retained in SK-N-SH human neuroblastoma cells in vitro to a higher degree than the MIBG. Method To investigate whether the higher retention of FIBG is due to differences in the catabolic degradation of the two tracers, in vitro paired-label studies were performed using SK-N-SH cells. Results No detectable amount of benzyl amines, benzoic acids or hippuran derivatives, potential catabolites of these tracers, were seen in either case. Even after 48 h, the cell culture supernatants contained exclusively intact 1 2 5 I-MIBG and 1 2 5 I-FIBG. In contrast, in some cases, HPLC analysis of cell lysates indicated the presence of a very polar compound(s) as the predominant species with smaller quantities of intact tracers. The per cent total radioactivity in the lysate at each time point that was associated with intact 1 2 5 I-FIBG was (average [range]) 25.4% [20.3-30.5], 22.5% [19.3-25.6], and 18.8% [14.3-23.3], at 0h, 24 h and 48 h, respectively. The corresponding values for 1 2 5 I-MIBG were 24.3% [21.0-27.5], 19.1% [11.7-26.5] and 17.4% [14.6-20.1]. No significant amount of activity was associated with high molecular weight species for either halobenzylguanidine, indicating that protein binding was not a major factor.
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Ring-and side-chain-substituted MIBG analogues
Journal of Labelled Compounds and Radiopharmaceuticals, 2001Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Philip Welsh, Sriram Shankar, S. A. Slade, Michael R. ZalutskyAbstract:In our effort to develop an MIBG analogue with optimised targeting capabilites, we have synthesized a number of ring- and side-chain substituted analogues of MIBG and evaluated their lipophilicity, stability in vitro, uptake in SK-N-SH human neuroblastoma cells and tissue distribution in normal mice. Previously, uptake similar to or higher than that for MIBG in canine adrenal medulla and pheochromocytoma patients has been reported for 4-amino-3-Iodobenzylguanidine (pAIBG) and 4-hydroxy-3-Iodobenzylguanidine (HIBG), which are polar substituent-containing MIBG derivatives (1, 2). However, these two compounds have not been evaluated with respect to their uptake in neuroblastoma cells in vitro. The novel compounds developed in this study were evaluated in comparison with HIBG and pAIBG.
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Validation of 4-[fluorine-18]fluoro-3-Iodobenzylguanidine as a positron-emitting analog of MIBG
Journal of nuclear medicine : official publication Society of Nuclear Medicine, 1995Co-Authors: Ganesan Vaidyanathan, Donna J. Affleck, Michael R. ZalutskyAbstract:This study evaluates the potentialutilItyof 4-[18Fjfluoro-3-iodo benzylguanidrie((‘@FJF1BG) as an MIBGanalog. Methods In vitroassays of tracer bindingwere earned out using the SK N-SHhumanneuroblastomacelllinein a paired-labelformatto compare[1819F1BG dlrecdywfth no-carA±er-edded (meqMlBG. To ascertaln whether E18FIF1BG, like MIBG,is taken up by the uptake-I mechanism,the effects of desipramine,norepineph rine, and carder MIBGand ABG on cell birdng were deter mined.Preincubationwithouabeln and incubationat 4°C was used to evaluatethe energy-dependenceof(1@F1FlBG u@akeby SK-N-SH cells. Thetissue dIstribution of[18FIF1BG inmicewas compared w@ino-earner-added(1eIJMIBG in a paired-label study.Results:Inpaired-label binding studies,thepercentbind ing of [1@I9FIBG to neuroblastoma cells remained constant over a three-logactivIty rangeandthe levelwas somewhathigher thanthatofno-carner-added[1@I)MIBG. Bsrdngwas blockedby desiprarr*ie,norepinephrlne,carder MIBGand FIBG,ouabain and by incubatingat 4°C, suggestingthat [18FIHBG Istaken up by the uptake-i mechanism.Rediationdosimetrycalculations suggestthat higherdoses of [1@FJF1BG, unlike[124IJMIBG, could be administeredto patients.Conclusion: These in vitroand in vflloevaluationsshow that [1°FJABG Is an exceUentanalog of MIBG, suggestingthat 11°FIABG shouldbe furtherevaluatedfor use in PETimagingof neuroendocA±ne tumorsand cardiacab normaildes.
G Vaidyanathan - One of the best experts on this subject based on the ideXlab platform.
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3-[211At]astato-4-fluorobenzylguanidine: a potential therapeutic agent with prolonged retention by neuroblastoma cells
British Journal of Cancer, 1997Co-Authors: G Vaidyanathan, X-g Zhao, Rh Larsen, Mr ZalutskyAbstract:An analogue of meta-Iodobenzylguanidine (MIBG) in which an aromatic hydrogen was replaced with fluorine has been found to possess many properties similar to those of the parent compound. Moreover, 4-fluoro-3-Iodobenzylguanidine (FIBG) was retained in vitro by human neuroblastoma cells to a much greater extent than MIBG itself. Since alpha-emitters such as 211At could be valuable for the treatment of micrometastatic disease, an FIBG analogue in which the iodine atom is replaced by 211At would be of interest. In this study, we have evaluated the in vitro and in vivo properties of 3-[211At]astato-4-fluorobenzylguanidine ([211At]AFBG). The specific binding of [211At]AFBG to SK-N-SH human neuroblastoma cells remained fairly constant over 2- to 3-log activity range and was similar to that of [131I]MIBG. The uptake of [211At]AFBG by this cell line was reduced by desipramine, ouabain, 4 degrees C incubation, noradrenaline, unlabelled MIBG and FIBG, suggesting that its uptake is specifically mediated through an active uptake-1 mechanism. Over the 16 h period studied, the amount of [211At]AFBG retained was similar to that of [131I]FIBG, whereas the per cent of retained meta-[211At]astatobenzylguanidine ([211At]MABG) was considerably less than that of [131I]FIBG (53% vs 75%; P < 0.05). The IC50 values for the inhibition of uptake of [131I]MIBG, [211At]MABG, [125I]FIBG and [211At]AFBG by unlabelled MIBG were 209, 300, 407 and 661 nM respectively, suggesting that the affinities of these tracers for the noradrenaline transporter in SK-N-SH cells increase in that order. Compared with [211At]MABG, higher uptake of [211At]AFBG was seen in vivo in normal mouse target tissues such as heart and, to a certain extent, in adrenals. That the uptake of [211At]AFBG in these tissues was related to the uptake-1 mechanism was demonstrated by its reduction when mice were pretreated with desipramine. However, the stability of [211At]AFBG towards in vivo dehalogenation was less than that of [211At]MABG, as evidenced by the higher uptake of 211At in thyroid, spleen, lungs and stomach.
