Somatostatin analogues labelled with radiometals or radiohalogens are useful for the imaging and ... more Somatostatin analogues labelled with radiometals or radiohalogens are useful for the imaging and treatment of somatostatin receptor-containing tumours. In this study, the procedures for the radioiodination of glucose-Tyr3-octreotate (gluc-Tyr3-tate) and radiolabelling of DOTA-Tyr3-octreotate (DOTA-Tyr3-tate) with 111In, 177Lu and 125I were compared and their metabolism in rats was analyzed. The usefulness of high performance liquid chromatography (HPLC) analysis and instant thin-layer chromatography on silica gel (ITLC-SG) for both radiochemical purity determination and analysis of metabolism in urine was investigated. For labelling with radiometals, the formation of a complex with the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) functionality of the peptide was employed. Radioiodination was performed by the chloramime-T method. The radiochemical purity of radiolabelled peptides and the analyses of rat urine were determined by HPLC and/or ITLC-SG methods. Male Wis...
Due to their high CCK-2/gastrin receptor selectivity, high affinity, and rapid background clearan... more Due to their high CCK-2/gastrin receptor selectivity, high affinity, and rapid background clearance, radiolabeled minigastrins (MG) are emerging as promising new tools in the diagnosis and therapy of CCK-2/gastrin receptor-positive tumors. In this study, the pharmacokinetic profile, particularly the excretion mode, of two 111In-labeled minigastrins was compared in rats. The first tracer, 111In-MG-0 is based on (D)Glu1-MG, while the second, 111In-MG-11, is its des-(Glu)5-derivative, expected to be less retained in renal tissue. The fate of 111In-MG-0 and 111In-MG-11 in the body of rats was investigated during biodistribution and bioelimination experiments, while the respective elimination parameters were determined in perfused rat liver and kidney models. During biodistribution both compounds were rapidly cleared from the blood and most non-target organs whereas activity levels in the bowel and stomach declined slowly. The overall contribution of hepatobiliary excretion of 111In-MG-0...
Siderophores are low-molecular-mass iron chelators serving as iron transporters for almost all ba... more Siderophores are low-molecular-mass iron chelators serving as iron transporters for almost all bacteria, fungi and some plants. Iron is an essential element for majority of organisms and plays an important role in virulence of pathogenic organisms. (68)Ga is a positron emitter with complexing properties comparable to those of Fe(III) and readily available from a generator. Initial studies with (68)Ga-triacetylfusarinine C (TAFC) showed excellent targeting properties in a rat infection model. We report here on the in vitro and in vivo evaluation of other siderophores radiolabelled with (68)Ga as potential radiopharmaceuticals for infection imaging.
Somatostatin analogues labelled with radiometals or radiohalogens are useful for the imaging and ... more Somatostatin analogues labelled with radiometals or radiohalogens are useful for the imaging and treatment of somatostatin receptor-containing tumours. In this study, the procedures for the radioiodination of glucose-Tyr3-octreotate (gluc-Tyr3-tate) and radiolabelling of DOTA-Tyr3-octreotate (DOTA-Tyr3-tate) with 111In, 177Lu and 125I were compared and their metabolism in rats was analyzed. The usefulness of high performance liquid chromatography (HPLC) analysis and instant thin-layer chromatography on silica gel (ITLC-SG) for both radiochemical purity determination and analysis of metabolism in urine was investigated. For labelling with radiometals, the formation of a complex with the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) functionality of the peptide was employed. Radioiodination was performed by the chloramime-T method. The radiochemical purity of radiolabelled peptides and the analyses of rat urine were determined by HPLC and/or ITLC-SG methods. Male Wis...
Due to their high CCK-2/gastrin receptor selectivity, high affinity, and rapid background clearan... more Due to their high CCK-2/gastrin receptor selectivity, high affinity, and rapid background clearance, radiolabeled minigastrins (MG) are emerging as promising new tools in the diagnosis and therapy of CCK-2/gastrin receptor-positive tumors. In this study, the pharmacokinetic profile, particularly the excretion mode, of two 111In-labeled minigastrins was compared in rats. The first tracer, 111In-MG-0 is based on (D)Glu1-MG, while the second, 111In-MG-11, is its des-(Glu)5-derivative, expected to be less retained in renal tissue. The fate of 111In-MG-0 and 111In-MG-11 in the body of rats was investigated during biodistribution and bioelimination experiments, while the respective elimination parameters were determined in perfused rat liver and kidney models. During biodistribution both compounds were rapidly cleared from the blood and most non-target organs whereas activity levels in the bowel and stomach declined slowly. The overall contribution of hepatobiliary excretion of 111In-MG-0...
Siderophores are low-molecular-mass iron chelators serving as iron transporters for almost all ba... more Siderophores are low-molecular-mass iron chelators serving as iron transporters for almost all bacteria, fungi and some plants. Iron is an essential element for majority of organisms and plays an important role in virulence of pathogenic organisms. (68)Ga is a positron emitter with complexing properties comparable to those of Fe(III) and readily available from a generator. Initial studies with (68)Ga-triacetylfusarinine C (TAFC) showed excellent targeting properties in a rat infection model. We report here on the in vitro and in vivo evaluation of other siderophores radiolabelled with (68)Ga as potential radiopharmaceuticals for infection imaging.
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Papers by Milos Petrik