By means of comparing seasonal distribution of births between the Japanese encephalitis (JE) patients in the JE epidemics during 1948-64 and the general population in Tokyo, the susceptibility difference to an apparent infection of JE virus by their season of births was investigated.
The JE patients who suffered from JE clinically at the age of 1-29, were more frequently born during the epidemic season of the epidemic years than what was expected from the seasonal birth frequencies of the general population. On the contrary, the number of JE patients born in the summer season of the non-epidemic years was nearly the same as expected from the general births in the same years. This may imply the possibility that the susceptibility to JE virus infection has been kept modified for many years by the inapparent infection of the JE virus in their fetal or neonatal stages.

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The contamination and the pollution of foodstuffs by radioactive fallout have been investigated since 1961 in Fukuoka city and its suburban area. The results obtained were as follows.
1) Recently, the degree of the contamination of greens by radioactive fallout which fell on the leaves decreased to one thousandth in the early stage of the investigation (1961-1962). In the period of the investigation, the remarkable increase of the radioactivity of fallout was observed within a week after the Chinese nuclear bomb explosion in the atmosphere (1st, 2nd, 5th, 12th, 13th, and 15th). The radioactivity was 2 to 300 times higher than the usual level.
2) The radioactivity was not remarkable in vegetables which were washed with soap, but it decreased gradually year by year. The increase of the radioactivity was also observed a few days after the atmospheric nuclear explosion.
3) In milk, there were no remarkable yearly decreases of the radioactivity from the beginning of the investigation, but the seasonal variations of the radioactivity, such as higher in April and May, were observed.
4) The radioactivity in diets based on the standard food production in Japan was the highest in 1967. It decreased gradually from 1967 to 1971 and after that the remarkable variation of the activity was not observed.
5) ¹³⁷Cs contamination of foodstuffs has been observed quantitatively by the method of gamma spectrometry, while sometimes ⁹⁵Zr-⁹⁵Nb, ¹⁰³Ru, and ¹³¹I were also detected from the specimens obtained immediately after the nuclear explosions.

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The mechanisms of experimental external contamination which was obtained by immersing hair specimens in solution, especially the contamination through the airsac in medulla on cross section of hair was studied.
The hair specimens which have medulla and obtained from one person were cut into the sections of 2cm in length. Untreated hair, the hair covered with Araldite on one end and the hair covered with Araldite on both ends were prepared. These hairs were contaminated externally by immersing them in NaCl solutions with sodium concentration of 9.4×10⁴ppm and pH values of 7 and 11.1 for 1 hour and 24 hours. These contaminated hairs were cut into three portions along the major axis and sodium contents were determined by atomic absorption spectrometry. The distribution of sodium on the cross sections of other parts of the above specimens was determined by electron probe X-ray microanalyzer (XMA).
XMA used was a JEOL SMU3-SDS. The operating conditions were 20KV acceleration voltage, 7.5-9.5×10^-9A specimen current, RAP for Na-Kα as crystal and×500 magnification.
The higher the pH value in immersing solution and the longer the immersing time, the higher the sodium contents in contaminated hair. One difference in sodium content was observed in the means of the three portions of untreated hair and the hair covered with Araldite on both ends which were immersed in the solution with pH value of 11 for 24 hours.
As a result of XMA, gradual impregnations of sodium into the inner part of hair from outer layer were observed in the samples immersed in the solutions with pH value of 7 and 11 for 1 hour and all samples were impregnated with sodium into the medulla by the immersion for 24 hours. The higher the pH value, the faster the permeance. Especially higher sodium concentrations in medulla were observed in the samples immersed in the solution with pH value of 11 for 24 hours, regardless of the treatment with Araldite.
It was thought that the higher sodium observed in the medulla of the hair covered with Araldite on both ends penetrated from cuticle of hair, because Araldite did not permeate NaCl solution. In addition, it was demonstrated that sodium penetrated also in the direction of hair axis, from the fact that in the hair covered with Araldite on both ends, sodium was detected also in the part of the hair covered entirely with Araldite.

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Changes of growth and cell components of Geotrichum candidum belonging to sewage fungi were examined in synthetic medium containing heavy metals (Hg⁺⁺, Cu⁺⁺ and Zn⁺⁺) and cyan.
The growth of G. candidum in medium was greatly inhibited in response to increasing amount of the tested poisons. The fungous grown in CN^-medium showed morphologically mycelium (filamentous) phase cells in which possess only a few septa, but in Cu⁺⁺ or Zn⁺⁺ medium abnormal mycelium and yeast-like phase were observed microscopically.
An increase of total sugar, 3%-NaOH soluble polysaccharide and total nucleic acids was generally found in the Cu⁺⁺ and Zn⁺⁺ media in proportion to metal concentration. Glucosamine content was reduced in Cu⁺⁺-containing medium, and DNA level was increased. However, appreciable quantitative change in these components was not observed in cells grown on CN^- and Hg⁺⁺ media.
By addition of CN^- or Cu⁺⁺ in the medium G. candidum was increased RQ value in their cell respiration.

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The effect of stannous chloride on the bile calcium concentration in rats was examined in these experiments. The bile calcium concentration in rats that had fasted for 2 hours was significantly increased by a single oral administration of tin (3.0mg/100g body weight). An oral administration of tin to rats elevated the bile calcium concentration with three doses (1.0, 3.0 or 5.0mg of Sn/100g) of tin employed. Also, the bile calcium concentration and bile volume showed a significant increase in rats administered orally with tin (3.0mg/100g) during 3 days. On the other hand, the increased bile volume produced by the treatment of tin reduced to the control level at 66 hours after the orall administration with tin during 3 days, while the bile calcium concentration increased significantly. This fact indicates that the augmentation of blie calcium concentraion after the administration of tin is not related to the elevation of bile volume.

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Cadmium chloride administered intraperitoneally to rats caused a mainly dose-dependent decrease of microsomal protein and the cytochrome P-450 contents in the hepatic microsomal drug-metabolizing enzyme system. This dose-dependent decrease of cytochrome b₅ was slight. The concentrations of cadmium that decreased the activity of this system show no effect on sGOT and sGPT activity in this experiment.
Cadmium added in vitro caused the denaturation of cytochrome P-450 to cytochrome P-420, and the denaturation was dependent on the concentration of cadmium.
Experiments on the effect of cadmium on the activity of aminopyrine demethylase and aniline hydroxylase dependent cytochrome P-450 were conducted in vivo and in vitro. The specific activity of the former was decreased more remarkably than that of the latter by cadmium administered in vivo. On the other hand, in in vitro experiment, aniline hydroxylase was inhibited much more than aminopyrine demethylase.
Enzyme kinetics to determine the inhibitory mechanism of aminopyrine demethylase and aniline hydroxylase were also conducted.
These results may indicate that the decrease of drug-metabolizing enzyme activity is mainly due to the denaturation of cytochrome P-450 rather than the inhibition of the terminal oxidase by cadmium.

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We examined cytogenetically the mutagenic effects of cadmium on the oogenesis (from diakinesis/metaphase I stage to metaphase II stage) of the ddY/F mice in vivo.
For the synchronization and stimulation of ovulation, mice were intraperitoneally injected with 5 i.u. of pregnant mare's serum (PMS), and 48 hours later they were also injected with 5 i.u, of human chorionic gonadotropin (HCG). Three hours after the application of HCG, the mice of the experimental groups were given a single subcutaneous injection of 3.0mg or 6.0mg/kg. b. wt. of cadmium chloride. Chromosome analysis was performed on unfertilized metaphase II oocytes recovered from the Fallopian tubes 12 hours after injection of cadmium.
The chromosome anomalies observed in the 3mg-and 6mg-cadmium treated groups were numerical ones such as hypohaploidy (n-1), hyperhaploidy (n+1) and diploidy (2n). When analyzed on the litter and oocyte basis, these chromosomal anomalies increased in the cadmium treated groups as compared with the control group. However no structural anomalies of metaphase II chromosomes were observed. As a toxic effect of cadmium, heavier and diffuse haemorrhage was observed on the ovaries in some of the cadmium treated females. Concentrations of cadmium in the ovaries after 12 hours of cadmium injection were 2.5μg/g and 5.0μg/g for 3mg and 6mg treated groups, respectively.
The results indicate that cadmium has the potentiality of a mutagen in mammalian meiotic chromosomes. We propose that chromosome analysis of oocytes may be one of the useful methods for the screening of mutagenicity of environmental contaminants in mammalian germ cells in vivo.

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The static and dynamic adsorption characteristics of hydrogen sulfide on activated carbons and zeolites were investigated to obtain some fundamental information on the removal of hydrogen sulfide in the gaseous phase. The amount adsorbed and the rate of adsorption were measured by the static method, and the service time was measured by the dynamic method. The adsorption of hydrogen sulfide on adsorbents was expressed by Freundlich's equation at equilibrium concentrations up to 70, 000ppm. Among the 24 kinds of adsorbents, the amount adsorbed on activated carbons No.4 and No.8, and zeolites No.16 and No.17 was 36.50, 35.42, 69.23, and 87.55ml/g at 70, 000ppm, respectively, and their adsorption attained equilibrium within about ten minutes. It may be concluded that the amount adsorbed on adsorbents was mainly affected by their pore volume in the range of pore radii from 2.2 to 6.5Å rather than by their chemical properties such as pH, pKa, basic amount, and acid amount. The heats of adsorption of Nos. 4, 8, 16, and 17 were less than 18kcal/mol. The amount chemisorbed on the activated carbons and the zeolites was about ten and two %, respectively and, therefore, these adsorbents used seemed to be regenerated by some simple treatment to the extent of the original adsorption capacity. Among the 8 kinds of adsorbents, the service time of No.8 and No.17 (9∼20 mesh) with a concentration of hydrogen sulfide 7, 000ppm at a flow rate of the mixed gas (H₂S-air) 650ml/cm²⋅min was 23 and 65 minutes, respectively, and no correlation was established between the amount adsorbed and the service time. A linear relationship existed between the service time and the length of column, and the service time was inversely proportional to the flow rate of the mixed gas and the concentration of hydrogen sulfide.

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