Yosihiko Kasida

18F-fluorination by crown ether-metal fluoride: II. Non-carrier-added labeling method

Abstract For non-carrier-added 18F-labeling of organic compounds, details were studied concerning the previously developed KF-crown ether method. In the modified method, a minute amount of KOH instead of carrier KF is added for the preparation of the anhydrous 18F from aqueous carrier-free 18F. The following factors were examined in order to determine optimum conditions for the preparation of the anhydrous non-carrier-added 18F and the labeling synthesis with it: effects of the vessel on the evaporation of the 18F-KOH solution and the amount of added KOH for the conversion of aqueous 18F to anhydrous 18F, the solubilized activity of the 18F obtained by the evaporation in organic solutions containing 18-Crown-6 and the labeling reaction, as exemplified by the synthesis of 21-fluoroprogesterone.

18F-Fluorination by crown ether—metal fluoride: (I) On labeling 18F-21-fluoroprogesterone

Abstract 18F-Fluorination by “naked” 18F− anion produced by complexing anhydrous K18F, which was prepared from aqueous 18F, with 18-Crown-6 was described for preparing 18F-21-fluoroprogesterone. In order to find out optimum conditions in this labeling method, various factors were investigated such as the solubility of KF in organic solvents containing 18-Crown-6 and its reactivity for the nucleophilic displacement of 21-mesylate of progesterone. Chloroform was a good solvent in solubilization of KF and its reactivity. Problems in this labeling procedure were also examined, such as a supporter for transferring the labeled anhydrous K18F and reaction vessels. Use of a Teflon reaction vessel resulted in a good radiochemical yield based on the starting activity of [18F]water.

Biosynthesis of skimmianine

Abstract Skimmianine isolated from Skimmia plants fed with anthranilic acid- 3 H, acetate-2- 14 C and DL-tryptophan-3- 14 C was shown to be radioactive. Degradation of the labeled skimmianine showed that the radioactivity was located in the benzene ring when anthranilic acid- 3 H was administered, while it was located at the position 3 of quinoline nucleus when acetate-2- 14 C or DL-tryptophan-3- 14 C was used as the labeled precursors. On the basis of these results, a scheme of the biosynthesis of skimmianine was proposed in which skimmianine was shown to be derived from anthranilic acid and acetate.

Hydrogen exchange in uracil with HTO and D2O catalyzed by platinum

Abstract The kinetics of hydrogen exchange at the 5- and 6-positions of uracil with HTO and D 2 O catalyzed by Pt-black was investigated. A peculiarity which is characteristic of heterogeneous reactions was observed, and the growth of the reaction interface was explained by the reorientation of the mono-labelled intermediate. A reaction mechanism based on an associative process was proposed, the mechanism was verified by a hydrogen-exchange experiment with 2,4-dimethoxypyrimidine, where only the 6-position was labelled.

Remote-controlled System for a Large Scale Production of Short-lived Radioactive Substances with Cyclotron

核医学的な臨床利用に十分な量の短寿命RI (11CO, 11CO2, 13NN, 13NH3, 18F-, 62Zn2+, 123I-など) の生産が可能で, しかもそれらの生産条件の検討や迅速分析などにも利用できる短寿命RI生産システムの開発を行った。このシステムを利用することにより臨床利用の可能な数+mCiの短寿命RIを遠隔的に, しかも放射性ガス (11CO, 11CO2, 13NN) の場合は連続的に, そして放射性液体 (13NH3, 18F-など) の場合は数分の待時間で繰り返して生産することができた。一方作業者の被ばく線量はこのシステムの設置により大幅に減少した。

Simple Method for Producing 13NN and 15OO by Proton Bombardment of Aqueous Phase

A simple method has been developed for the production of 13NN and 15OO by proton irradiation of aqueous solutions. 90 mCi of 13NN was obtained in a 200 ml. of He by using 1.0M NH4CI solution at pH 11 as the target with 10 min irradiation of 15 MeV, 10 microamperemeter protons. 80 mCi/min of 15OO was continuously obtained in a 200 ml of O2 by using pure water as the target with 40 MeV, 2 microamperemeter protons. The radiochemical purity of these short-lived radioactive gases obtained by this method was greater than 99.9% by passing through a single absorber.

Fundamental Studies on Clinical Application of 13N-ammonia

放医研の医療用サイクロトロンを利用して, 13N-アンモニアを製造し, これの家兎の腸管内および静注の2つの投与経路での肝および心の13N-放射能動態の観察を行った。これに基づき, アンモニア代謝モデルを設定し, その解を適当な近似式に変換し, これにより腸管からのアンモニア吸収能, 肝内門脈分布, 実質細胞分布などで規定される諸パラメータ抽出の理論を展開した。