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Takada Y.,Japan National Institute of Radiological Sciences | Takada Y.,Yokohama City University | Ogawa M.,Japan National Institute of Radiological Sciences | Ogawa M.,SHI Accelerator Service Co. | And 2 more authors.
Applied Radiation and Isotopes | Year: 2010

Automated radiosynthesis of [2- 11C-carbonyl]dantrolene, the substrate of breast cancer resistance protein (BCRP/ABCG2), was performed for the first time through a multi-step/one-pot labeling sequence that started with ethyl 2-{2-[5-(4-nitrophenyl)furfurylidene]hydrazino}acetate and used [ 11C]phosgene as a labeling agent. After optimization of the automated synthesis conditions and parameters, [2- 11C-carbonyl]dantrolene was obtained at a radiochemical yield of 34.0±8.4% (decay-corrected). The radiochemical purity was greater than 98% and the specific activity was 46.8±15.2GBq/μmol at the end of the synthesis. © 2010 Elsevier Ltd. Source


Ogawa M.,Japan National Institute of Radiological Sciences | Ogawa M.,SHI Accelerator Service Co. | Takada Y.,Japan National Institute of Radiological Sciences | Takada Y.,Yokohama City University | And 3 more authors.
Nuclear Medicine and Biology | Year: 2010

Introduction: Carbon-11-labeled phosgene is an important labeling precursor for PET molecular probes. Despite the usefulness of [11C]phosgene, some difficulties, especially in the formation of [11C]phosgene process from [11C]CCl4, hamper its use. The present article shows a simple preparation method for [11C]phosgene. Method: [11C]CCl4 was obtained using the conventional method by passing a mixture of [11C]CH4 and Cl2 through a heated quartz tube. The [11C]CCl4 was transformed to [11C]phosgene simply by passing through a pretreatment tube of a Kitagawa gas detection system for the working-environmental CCl4 concentration measurement at room temperature with a flow rate of 50 ml/min. Result: This tube successfully transformed [11C]CCl4 to [11C]phosgene at room temperature. [11C]Phosgene was obtained at nearly 80% radiochemical yield (EOB) in a short synthesis time with high reproducibility. Conclusion: A high yield and reliable [11C]phosgene production method using a gas detector tube system for working-environmental CCl4 concentration measurement was developed. © 2010 Elsevier Inc. All rights reserved. Source


Fujinaga M.,Japan National Institute of Radiological Sciences | Yamasaki T.,Japan National Institute of Radiological Sciences | Yamasaki T.,Tohoku University | Maeda J.,Japan National Institute of Radiological Sciences | And 9 more authors.
Journal of Medicinal Chemistry | Year: 2012

Three novel 4-substituted benzamides have been synthesized as potential ligands for the positron emission tomography (PET) imaging of metabotropic glutamate 1 (mGlu1) receptor in the brain. Of these compounds, N-(4-(6-(isopropylamino)pyrimidin-4-yl)-1,3-thiazol-2-yl)-N,4-dimethylbenzamide (4) exhibited the highest binding affinity (Ki = 13.6 nM) for mGlu1 and was subsequently labeled with carbon-11. In vitro autoradiography using rat brain sections showed that [11C]4 binding was consistent with the distribution of mGlu1, with high specific binding in the cerebellum and thalamus. PET studies with [11C]4 in monkey showed a high brain uptake and a kinetic profile suitable for quantitative analysis. Pretreatment with a mGlu1-selective ligand 16 largely decreased the brain uptake, indicating high in vivo specific binding of [11C]4 to mGlu1. In metabolite analysis, only unchanged [11C]4 was found in the brain. [ 11C]4 is a useful PET ligand for the imaging and quantitative analysis of mGlu1 in monkey brain and merits further evaluation in humans. © 2012 American Chemical Society. Source


Yamasaki T.,Japan National Institute of Radiological Sciences | Fujinaga M.,Japan National Institute of Radiological Sciences | Yui J.,Japan National Institute of Radiological Sciences | Ikoma Y.,Japan National Institute of Radiological Sciences | And 7 more authors.
Journal of Cerebral Blood Flow and Metabolism | Year: 2014

Because of its role in multiple central nervous system (CNS) pathways, metabotropic glutamate receptor type 1 (mGluR1) is a crucial target in the development of pharmaceuticals for CNS disorders. N-[4-[6-(isopropylamino)- pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methyl-4-[11C]-methylbenzamide ([11C]ITDM) was recently developed as a positron emission tomography (PET) ligand for mGluR1. To devise a method for measurement of the binding potential (BPND) of [11C]ITDM to mGluR1, reference tissue methods aimed at replacing measurement of the arterial input function are desirable. In this study, we evaluated a noninvasive quantification method of mGluR1 with [11C]ITDM, demonstrating its accuracy using Huntington disease model R6/2 mice. The BPND measurements based on the Logan reference (Logan Ref) method have closely approximated that based on the arterial input method. We performed PET analysis with Logan Ref to assess its accuracy in quantifying the decline of mGluR1 expression in R6/2 mice. Significant decreases in BPND values in R6/2 mice were detected in cerebellum, thalamus, striatum, and cingulate cortex. We compared autoradiographs of R6/2 mouse brain sections with immunohistochemical images, and found a close correlation between changes in radioactive signal intensity and degree of mGluR1 expression. In conclusion, [11C]ITDM-PET is a promising tool for in vivo quantification of mGluR1 expression. © 2014 ISCBFM All rights reserved. Source


Hayashi K.,Oita University | Douhara K.,Oita University | Douhara K.,SHI Accelerator Service Co. | Kashino G.,Oita University
Annals of Nuclear Medicine | Year: 2014

Objective: We developed a bubble point test kit and investigated the bubble point test of a 0.22-μm membrane filter used for the sterilizing filtration of [18F]FDG, [11C]MET and [11C]PIB. The bubble point test of the Millex-GS vented filter was often difficult due to air leakage from the vented portion of this filter. Therefore, to close the vented portion of this filter simply and reliably, we investigated the use of various materials. Methods: The bubble point test of the Millex-GS vented filter was performed by closing the vented portion of this filter with various materials, such as vinyl tape, plastic paraffin film (parafilm), urethane elastomer adhesive mat and polyethylene foam cushion tape. Gradually, the plunger inside a syringe filled with air was pushed down to increase the pressure on the pressure gauge and the bubble point test kit. Simultaneously, the pressure when a continuous stream of air bubbles that appeared out of the 0.22-μm membrane filter was measured as the product-wetted bubble point value. Then, the plunger inside a syringe filled with 10 mL of water was pushed down to wash the 0.22-μm membrane filter. As in the case in the above-mentioned method of measuring the product-wetted bubble point, the water-wetted bubble point value was measured. Results: The use of the polyethylene foam cushion tape and a double clip could easily and reliably prevent air leakage from the vented portion of the Millex-GS vented filter. In the bubble point test of [ 18F]FDG, [11C]MET and [11C]PIB, the product-wetted bubble point values were 382.7 ± 6.9 kPa, 385.4 ± 6.2 kPa and 351.6 ± 7.6 kPa, respectively. The bubble point ratio was used to determine the minimum product-wetted bubble point value. All results of the product-wetted bubble point test were beyond the minimum product-wetted bubble point value (334.4 kPa ([18F]FDG), 334.4 kPa ([ 11C]MET) and 310.3 kPa ([11C]PIB)). Then, the water-wetted bubble point values were 396.5 ± 8.3 kPa, 395.8 ± 8.3 kPa and 390.3 ± 7.6 kPa, respectively. All results of the water-wetted bubble point test were beyond the filter manufacturer's minimum bubble point specification (344.8 kPa). Conclusions: The bubble point test technique using the bubble point test kit was practical for routine quality control tests of PET radiopharmaceuticals. © 2014 The Japanese Society of Nuclear Medicine. Source

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