Kazuhiro Inafuku

Biological Monitoring of Solar UV Radiation at 17 Sites in Asia, Europe and South America from 1999 to 2004

Abstract A small and robust dosimeter for determining the biologically effective dose of ambient UV radiation has been developed using UV-sensitive mutant spores of Bacillus subtilis strain TKJ6312. A membrane filter with four spots of the spores was snapped to a slide mount. The slide was wrapped and covered with two or more layers of polyethylene sheet to protect the sample from rain and snow and to reduce monthly-cumulative doses within the measurable range. From 1999, monthly data were collected at 17 sites for more than 1 year, and data for 4 to 6 consecutive years were obtained from 12 sites. Yearly total values of the spore inactivation dose (SID) ranged from 3200 at subarctic Oulu to 96 000 at tropical Denpasar, and the mean yearly values of SID exhibited an exponential dependence on latitude in both hemispheres with a doubling for about every 14 degrees of change. During the observation period, increasing trends of UV doses have been observed at all sites with more than 5 years of data available. Year-to-year variations at high and middle latitude sites are considered due mostly to climatic variation. At three tropical sites, negative correlations between the yearly doses and the column ozone amounts were observed. The results verified the applicability of spore dosimetry for global and long-time monitoring of solar UV radiation, in particular at tropical sites where no monitoring is taking place.

Alteration of mRNA levels of δ-aminolevulinic acid synthase, ferrochelatase and heme oxygenase-1 in griseofulvin induced protoporphyria mice

Human erythropoietic protoporphyria (EPP) is an inherited disorder of porphyrin metabolism and its experimental murine model can be produced by treatment with griseofulvin (GF). We investigated the alteration of mRNA expression in ferrochelatase (FeC), delta-aminolevulinic acid synthase (ALAS) and heme oxygenase-1 (HO-1) in liver, skin and peripheral blood cells of GF-treated mice. In liver, ALAS mRNA was enhanced dramatically by GF administration, in accord with thesis that the expression of ALAS is regulated by feedback mechanism. The expression of HO-1 mRNA increased most rapidly and drastically in liver, however its mechanism of regulation may be different from that of ALAS mRNA. The level of FeC mRNA in liver was less affected with GF treatment. Our results indicate that the inhibition of FeC by GF administration might occur primarily at post-transcriptional level. Similar effects were observed in the ALAS and HO-1 mRNA expression in peripheral blood cells, 2-fold increase in the ALAS mRNA and increase from undetectable level to detectable level in the HO-1 mRNA. In skin of GF-treated mice, average increases of 1.3-fold in the ALAS mRNA and 1.6-fold in the HO-1 mRNA were statistically insignificant. The FeC mRNA level was not altered in peripheral blood or in skin of GF-treated mice. The present study indicates that the molecular analysis is practicable in skin and peripheral blood. In further study, this model could contribute to investigate the pathogenesis of clinical manifestation including possibly cutaneous changes in EPP.