The distribution of radioactivity in the mouse brain after intravenous administration of3H-paroxetine was in the order (highest to lowest) hypothalamus>cerebral cortex>cerebellum. The radioactivity in the hypothalamus and cerebral cortex after injection of3H-paroxetine was significantly decreased by treatment with 6-nitroquipazine or paroxetine. HPLC and TLC analyses show that no radioactive metabolites were found in the mouse brain 3 h after intravenous administration of3H-paroxetine. The present results indicate that3H-paroxetine would be a suitable radioligand for in vivo study of 5-HT uptake sites in mouse brain.
Dexamethasone (DEX) increased67Ga uptake by the liver and spleen at 4, 8, and even 24 h after the injection of67Ga. These results showed that DEX influenced67Ga accumulation as well as the initial entry of67Ga in the liver and spleen. On the other hand, indomethacine (IM) decreased67Ga uptake by the liver and spleen at 4 h after the injection of67Ga but did not influence the uptake at 8 or 24 h after the injection of67Ga. Moreover, DEX or IM little influenced67Ga uptake by the kidney and muscle. These results suggest that the influence of DEX or IM on67Ga uptake or accumulation is specific for the liver and spleen.
To evaluate the prognosis in 57 patients with old myocardial infarctions, 201Tl myocardial scintigraphy and99mTc-HSA gated blood pool scan had been done as a 5-year follow up study. We subdivided into two groups; group I (over 60 years) and group II (under 60 years) . Cardiac index (CI) and right ventricular ejection fraction (RVEF) did not change significantly, however left ventricular ejection fraction (LVEF) changed significantly (p<0.05) . Corelationship between CAG score and ΔLVEF by handgrip exercise test was y=-1.34x+3.61 (n=44, r=-0.400, p<0.01) . Otherwise, Tl defect ratio between first and final examination did not show the significant change in two groups. In conclusion, nuclear examination (cardiac function and myocardial blood flow) is significant to evaluate the prognosis in patients with myocardial infarction.
Tritium measurement system utilizing an ionization chamber is widely used but the memory effect often gives obstruction for accurate measurement. We designed a method of tritium removal from electrode surface utilizing an isotope exchange reaction, namely, water vapor mixing to the process gas just before entering the ionization chamber, and good results were observed for an ionization chamber made of copper or stainless steel. In case of the ionization chamber having stainless steel electrodes, smaller memory effect, though larger amount of tritium sorption, was observed than for the copper chamber, because of porous Fe3O4film formed on stainless steel surface.
Measurement was made to determine self-dose at Mihoro Dam Tunnel where cosmic-ray was fairly attenuated. The dosimeter with Pb and Sn filter had the same self-dose of 0.26 nCkg-1h-1as that without the filter. Our experiment shows that self-dose is due to any traces of natural radioactivity in the phosphor and the packaging. Cosmic-ray dose was evaluated 0.74 nC kg-1h-1from our experiment at sea surface, and this value was somewhat smaller than the cosmic-ray intensity in Japan. The reason is considered to be low TL response for cosmic-ray hard component.