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153 results on '"Kagei K"'

7. Repeated Proton Beam Therapy for Hepatocellular Carcinoma

Author

Hashimoto, T., primary, Tokuuye, K., additional, Nemoto, K., additional, Onishi, K., additional, Fukumitsu, N., additional, Igaki, H., additional, Hata, M., additional, Kagei, K., additional, Sugahara, S., additional, Ohara, K., additional, Matsuzaki, Y., additional, and Akine, Y., additional

Published
2005
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26. Absorption, distribution, metabolism and excretion of a new, 14C-labelled oxazolidinone MAO-A inhibitor in rat and dog.

Author

Naitoh, T., Mishima, M., Kawaguchi, S., Matsui, K., Andoh, T., Kagei, K., Kakiki, M., Yuzuriha, T., and Horie, T.

Subjects
CHEMICAL inhibitors, DRUG metabolism, CEREBRAL cortex, BLOOD proteins
Abstract

1. After oral administration of C-labelled (5 R )-3-\[2-((1 S )-3-cyano-1-hydroxypropyl)benzothiazol-6-yl]-5-methoxymethyl-2-oxazolidinone (E2011) at a dose of 1 mg kg, the blood level of radioactivity reached a maximum concentration ( C ) of max 0 545 mu g eq. ml after 0 25 h in the rat and of 0 900 mu g eq. ml after 0 5 h in the dog. In dog plasma, C for radioactivity and unchanged E2011 were 0 862 mu g eq. ml and 0 650 mu g ml max respectively with corresponding T (time at C ) of 0 75 and 0 25 h. The unchanged max max drug in dog plasma was below the detection limit (5 ng ml plasma) after 24 h. 2. The tissue levels of radioactivity were measured at 0 25 ( T ), 6, 24, and 168 h after max administration to the rat and at 0 5 ( T ), 24, and 168 h in the dog. The radioactivity was max distributed in all tissues examined at T in the rat and dog. The radioactivity levels of the max cerebral cortex in the rat and dog were 26 and 36% of the plasma level at T . The max radioactivity in tissues decreased at almost the same rate as that in plasma. Plasma protein binding of the unchanged drug in the rat in vitro were about 70% in the range of 0 1-10 mu g ml, and those in the dog were about 45% in the same concentration range. 3. Cumulative excretion of radioactivity in the rat was 74 5% in urine and 22 5% in faeces after 7 days. In the dog, 55 5 and 36 5% of the radioactivity administered were excreted in urine and faeces respectively after 7 days. The biliary excretion of radioactivity in the cannulated rat was 23 0% within 48 h. 4. In tlc analysis of plasma and tissues of the rat and dog, the radioactivity for the unchanged drug was much higher than metabolites. In tlc analysis of urine, the same metabolites were detected in the rat and dog, and the radioactivity of a metabolite, IM1, was the highest in the both animals. Eight metabolites were detected in the plasma, tissues and excreta of the rat, and four metabolites in the dog. 5. In conclusion, the absorption, distribution, metabolism and excretion of Clabelled E2011 in the rat and dog have been established, and only minor differences were observed between these species. [ABSTRACT FROM AUTHOR]

Published
1997
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39. Matrix Effect on Hydrogen Atom Tunneling from Alkane to Free Deuterium Atoms in Cryogenic Solid

Author

Ichikawa, T., Kagei, K.-i., Tachikawa, H., and Ishitani, Y.

Abstract

ESR study on alkyl radicals generated in deuterated organic matrixes at 77 K by hydrogen atom tunneling from alkane molecules to free deuterium atoms has been carried out for elucidating control factors for the tunneling. For small alkane molecules, the tunneling rate is determined by the height of the potential energy barrier for the tunneling. For larger molecules in glassy matrixes, the rate decreases with increasing number and length of alkyl chains bonded to a carbon atom to be hydrogen abstracted. The tunneling rate from antepenultimate tertiary carbon is much slower than that from penultimate secondary carbon, even the potential energy barrier is lower. This abnormal effect is explained as being due to the steric hindrance by matrix molecules to the deformation of alkane molecules during the reaction. The alkyl chains surrounded by matrix molecules prevent the deformation of the chemical bonds of the carbon atom from the initial sp3 to the final sp2 configuration, which may cause the increase of the thickness of the potential energy barrier and thereby decrease of the tunneling rate. Free deuterium atoms in a crystalline adamantane matrix selectively abstract hydrogen atoms from the antepenultimate tertiary carbon, probably due to less steric hindrance to the deformation.

Published
1999

46. Isotope Effect on Photoinduced Isomerization of Alkyl Radicals Trapped in 77 K Solid Alkanes

Author

Koizumi, H., Takada, T., Kagei, K., Ichikawa, T., and Yoshida, H.

Abstract

Photoinduced isomerization of protiated and deuterated hexyl radicals in 77 K solid n-hexanes was examined. 2- and 3-hexyl-h13 radicals in n-hexane-h14 isomerize to 1-hexyl-h13 radicals with the irradiation of 254 nm light. This isomerization is suppressed by replacing the six hydrogen atoms of the methyl groups with deuterium atoms. The quantum yield for the isomerization of 2- and 3-hexyl-1,1,1,6,6,6-d6 in n-hexane-1,1,1,6,6,6-d6 and of 2- and 3-hexyl-d13 in n-hexane-d14 is less than 1/16 of that of 2- and 3-hexyl-h13 radicals in n-hexane-h14. Photoinduced isomerization of hexyl-h13 radicals in 77 K n-hexane-d14 was also examined. 2- and 3-hexyl-h13 radicals isomerize to 1-hexyl-h13 radical even in the solid. The isomerization may hence occur through an intramolecular reaction. The large isotope effect may arise in the course of either the isomerization in the excited state or the relaxation process of the excited primary radical.

Published
1997

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