Tsuneo Kobayashi — Page 3

PubMed2002

Temporal variation of radon progeny ratio in outdoor air.

This paper investigates the concentration ratio of radon progeny (218Po, 214Pb, and 214Bi) in outdoor air. From 1988 to 1998, alpha spectroscopy was used intermittently to collect progeny data outside the author's office located in the northeastern part of Japan. Let the quantity R(EEC) represent the ratio EEC(218Po)/[EEC(214Pb) + EEC(214Bi)], where, e.g., EEC(218Po) denotes the equilibrium equivalent radon concentration contributed by 218Po. The concentration ratio R(EEC) correlates with outdoor air stability. Statistical and time series analyses of R(EEC) indicate (1) outdoor air is more stable in the morning than in the afternoon, (2) outdoor air is more stable in summer/autumn than in winter/spring, and (3) in spite of no significant correlation between R(EEC) and wind speed, the power spectrum of R(EEC) appears similar to that of wind speed. This is probably due to the fact that near-surface mixing is not very sensitive to wind speed.

Air Pollutants, Radioactive↗

PubMed2002

Short-term insulin treatment and aortic expressions of IGF-1 receptor and VEGF mRNA in diabetic rats.

We investigated the relationship between the changes in vascular responsiveness and growth factor mRNA expressions induced by 1-wk treatment with high-dose insulin in control and established streptozotocin (STZ)-induced diabetes. Aortas from diabetic rats, but not those from insulin-treated diabetic rats, showed impaired endothelium-dependent relaxation in response to ACh (vs. untreated controls). The ACh-induced nitrite plus nitrate (NOx) level showed no significant difference between controls and diabetics. Insulin treatment increased NOx only in diabetics. In diabetics, insulin treatment significantly increased the aortic expressions of endothelial nitric oxide synthase (eNOS) mRNA and VEGF mRNA. The expression of IGF-1 mRNA was unaffected by diabetes or by insulin treatment. In contrast, the mRNA for the aortic IGF-1 receptor was increased in diabetics and further increased in insulin-treated diabetics. In aortic strips from age-matched control rats, IGF-1 caused a concentration-dependent relaxation. This relaxation was significantly stronger in strips from STZ-induced diabetic rats. These results suggest that in STZ-diabetic rats, short-term insulin treatment can ameliorate endothelial dysfunction by inducing overexpression of eNOS and/or VEGF mRNAs possibly via IGF-1 receptors. These receptors were increased in diabetes, perhaps as result of insulin deficiency.

Acetylcholine↗