The effect of gamma irradiation on the growth rate, on the amount of soluble protein and on the amount of DNA in tobacco calli was analyzed. A significant decrease in the amount of DNA was detected in the calli of every growth stage after incubation for 24hfollowing irradiation at a dose that severely affected the growth of calli, although only a slight change was detected in the amount of soluble protein. No difference in the effect of irradiation on protein and DNA contents was detected among calli of different growth stages, although the amounts of protein and DNA in calli in each growth stage were different. The extent of the decrease in the amount of DNA of calli depended on both the dose which ranged from 0-300Gyand the time of incubation after irradiation. These results suggest that the rapid decrease in the DNA content of calli after irradiation is due to cellular systems that are induced by irradiation and that result in enzymatic degradation of DNA.
We evaluated the safety and clinical usefulness of cerebral and myocardial blood flow measurement by means of positron emission tomography (PET) with automated synthesis system of [15O] H2O (ARIS-02, JSW) in 62 patients with either brain disorder (n=31) or cardiac disease (n=31) . In all 62 patients, no side effects were detected after administering [15O] H2Ointravenously. The quality of the PET images were“fairly good”or“good”in all the cases. When compared with other imaging modalities such as computed tomography, this method provided physiological and functional information on the brain and cardiac diseases. We concluded that the PET measurement of cerebral and myocardial blood flow using automated synthesis system of [15O] H2Ois clinically useful.