The C-terminal amino acid in human milk lysozyme (HML) was found to be valine by the tritium labelling method. The yield of the radioactive valine was less than that of the radioactive leucine obtained from the C-terminal amino acid of hen egg white lysozyme (EWL). The second amino acid, -Gly-, of the C-terminal chain of HML may affect the tritiation.
The absorption of cadmium through the skin of rabbit and hairless mouse was represented by the accumulation in the liver and kidney. The accumulated amounts of cadmium in both organs of rabbit were found to be 0.4-0.6% for the applied cad-mium on the back skin for five weeks. The amounts in both organs of hairless mouse were found to be 0.2-0.8% for the applied cadmium on the back skin for one and two weeks.
Responses of delta-aminolevulinic acid (ALA) dehydrase activity in erythrocytes to cadmium, mercury and lead ions were investigated in vitro and in vivo. In vitro all of three metals inhibited the purified enzyme activity at the concentra- tion of 10-4M, indicating that the enzyme belongs to the sulfhydryl enzymes. On the other hand, the decrease of the enzyme activity below 40% of the control level was observed only in lead-treated mice, and in cadmium- or mercury-treated mice the transient decrease in the enzyme activity up to 40% of the control level in the initial stage was followed by the increase in the enzyme activity more than the control level in the later stage. It is concluded that both the decrease of the ALA dehydrase activity betow 40% of the control level and the increase in urinary ALA excretion are specific parameters for lead exposure.
Experiments were performed in order to investigate the cellular damage when asbestos particles were added to rat peritoneal macrophages in vitro. At short time after the addition of naked chrysotile, amosite or crocidolite to the cell culture the considerable amounts of lactic dehydrogenase (LDH) were released into the medium lacking serum and the content of acid soluble nucleotide in the cells decreased. Also C14-leucine incorporation into the cell protein was decreased by the addition of chryso- tile, crocidolite or amosite. Naked crocidolite and amosite decreased the lactic acid production after 24 hr incubation. But, when serum coated chrysotile, crocidolite or amosite were added to the macrophages the lactic dehydrogenase in the medium in- creased in small amount only after more prolonged incubation. Serum coated asbestos had no effect on the lactic acid production and C14-leucine uptake into cell protein of macrophages in the medium lacking serum, nor naked asbestos had any effect in the medium containing serum.
The tuffaceous sediments are widely distributed in Japan, and have utilized for building stone at every where for many centuries. The production of the tuffaceous sediments at Oya, Tochigi Prefecture, is regarded as the largest in Japan. This tuf- faceous sediment called Oya-ishi, contains many altered volcanic rock fragments. We have experienced that there are only 19% of oxygen in the air at some level of quarries where exposed large amount of altered materials in tuffaceous sediments. The accidents due to oxygen deficiency have happened and will be happened where the worksite is narrow and ill-ventilation, especially in places where are absorbent and/or dilution agents of oxygen. We found that the strong absorbent in the quarry is the altered volcanic material called Miso. The Miso is confirmed the mixture of ferrous dioctahedral and ferrous trioctahedral smectite which are situated in deep portions of the quarry, and are stable under the reducing environment. The Miso is commonly dark blue in colour in unweathered deep places, but easily turns to black within a few hour and finally to brown in a few weeks. The oxidized Miso is re- cognized as the mixture of ferric dioctahedral and ferric trioctahedral smectite without any other impurities such as iron oxides. The ferrous smectites being stable under the reducing condition, absorb oxygen to become the stable ferric smectites under the normal condition, and oxygen is consumed by this reaction. It may be a first report that ferrous iron in the structure of minerals is so easily and spontaneously oxidized to ferric iron in them under the normal temperature and environment.