Suzuki Kazutoshi

[13N]-β-phenethylamine ([13N]PEA): A prototype tracer for measurement of MAO-B activity in heart

[13N]beta-Phenethylamine ([13N]PEA) was evaluated as a radio tracer for the measurement of mouse heart monoamine oxidase (MAO) activity in vivo. After intravenous administration, [13N]PEA was deaminated by MAO-B. 13NH3 formed thereby was taken up by amino acids and trapped in the heart. The relation between the radioactivity trapped in the heart and the enzyme activity was examined. The radioactivity in the heart 15 min after administration was reduced in a dose-dependent manner by pretreatment with a specific MAO-B inhibitor, l-deprenyl, but not with a specific MAO-A inhibitor, clorgyline. A linear correlation existed between the heart radioactivity level and the heart MAO-B activity (0-45%). [13N]1,1-d2-2-Phenethylamine (C6H5-CH2-CD2-13NH2, [13N]d2PEA), a modified tracer with less reactivity towards the enzyme, was tested similarly. This tracer possessed a higher sensitivity than [13N]PEA, and a wider range (0-85%) of MAO-B activity correlated linearly with the trapped radioactivity. These results indicate that [13N]PEA derivatives ([13N]PEA and [13N]d2PEA) can be useful radiotracers for noninvasive measurements of MAO-B activity in the human heart.

Political Science and Multi-Agent Simulation: Affinities, Examples and Possibilities

Domestic politics and international relations are fertile fields for the analysis using multi-agent simulation. Both theoretically and empirically, such a technique can serve the development of political science. To attract scholarly attention, some illustrative examples may be helpful. Herein, more or less realistic analyses of different types of interactions between different types of agents are outlined: (1) the White House during the Cuban Missile Crisis in 1962; (2) three-layered interrelationship between voters, politicians and political parties; (3) the long-lasted civil war in the Sudan; and (4) trade friction in interdependent world. Note that the same “simulator” was used in all those analyses. This multi-purpose “simulator,” which has been developed in Japan, is introduced herein. Finally, some methodological possibilities are suggested.