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Analysis of free radical reaction in a sample irradiated by heaby-ion beam
https://repo.qst.go.jp/records/68941
https://repo.qst.go.jp/records/68941cc15279f-f7e0-4bcb-88d4-52282e127c79
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2007-05-09 | |||||
| タイトル | ||||||
| タイトル | Analysis of free radical reaction in a sample irradiated by heaby-ion beam | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Matsumoto, Kenichiro
× Matsumoto, Kenichiro× Nagata, Katsura× Yamamoto, Haruhiko× Anzai, Kazunori× 松本 謙一郎× 安西 和紀 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | The oxygen effect is severe problem in radiation therapies for hypoxic tumors using low linear energy transfer (LET) irradiation, such as X-ray and gamma-ray. Recent researches showed a fact that the around 2-fold oxygen effect was also obtained using high LET irradiation, such as heavy-ion beams. Although the carbon ion beam has been utilized to cancer therapy in Japan from 1994, detail mechanisms of interactions between the heavy ion beams and the biological systems were still in progress. When living tissue was irradiated by low LET irradiation, the redox status in the tissue can be changed due to several reactive species occurred in the cell during and after the irradiation. The oxygen consumption in the tissue may be changed by the damaging cells and/or its recovery process. The change of oxygen consumption also can affect to the redox status in the tissue. Since the oxygen effect has been considered as that is caused by free radical reactions of initial reactive species caused by ionization of water with oxygen to provide several reactive oxygen species (ROS), detection of free radical reactions in the sample irradiated by heavy-ion beams is important to understand the oxygen effect of high LET irradiation. Nitroxyl radicals are oxidized to the corresponding oxoammonium cation by ROS, such as hydroxyl radical and/or superoxide, which are generated directly by ionization of water and/or indirectly by sequential oxygen-mediated reactions. The oxoammonium cation can be reduced to the corresponding hydroxylamine by obtaining a hydrogen atom from hydrogen donor, such as GSH, HADH, and/or NADPH. When beta-ray, X-ray or gamma-ray is irradiated to a solution including TEMPOL and glutathione (GSH), the EPR signal intensity of the TEMPOL is decreased depending on the radiation doses. The reduction of TEMPOL does not occur without GSH. In this paper, detection of free radical reactions in a sample irradiated by a heavy-ion beam was tested. 10 g of gelatin was dissolved into 100 mL of 100 mM PBS (pH7) including 0.05 mM DTPA at 80degC. Another 200 mL of the PBS buffer (room temperature) was added to that hot gelatin solution. The gelatin solution was cool down to room temperature. Then, TEMPOL and GSH were added into the gelatin solution to make those concentrations 0.1 mM and 1 mM, respectively. This reaction mixture with gelatin was transferred into a 8.3 x 12.0 x 4.2 cm plastic container and fixed in a refrigerator for 2 hr. After the gelatin was fixed, the one side wall of the plastic container was opened. 290 MeV carbon beam was irradiated with parameters below; thickness of binary filter was 100 mm (Bragg peak will be 5 cm depth), size of collimator window was 1 x 1 cm, dose at surface was 16 Gy (5.99 x 10-5 Gy/count x 269898 count), and irradiation time was 127.3 s. The gelatin was sampled using glass capillary from several locations on and off the beam track after the irradiation. The gelatin sample was measured by X-band EPR. The EPR signals of TEMPOL in the samples from surface to Bragg peak on the beam track decreased compared with other locations. The EPR signal at the location 1 cm deeper from Bragg peak, however, decreased much lesser. The EPR signal at 2.5 cm deeper of Bragg peak showed almost no decreasing. The EPR signals from location off the beam track also showed almost no decreasing. Decreasing of EPR signal occurred continuously after irradiation. Extrapolated value of signal intensity to time 0 min from end of irradiation was almost the same for all locations. The free radical reactions may occurred in the sample after irradiation of heavy-ion beam within a very limited volume, where was from surface to Bragg peak on the beam track. |
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| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | A Joint Conference of the 12th In Vivo EPR Spectroscopy and Imaging and the 9th International EPR Spin Trapping/Spin Labeling | |||||
| 発表年月日 | ||||||
| 日付 | 2007-05-03 | |||||
| 日付タイプ | Issued | |||||
