Teiji Miura

Reduced mercury excretion with feces in germfree mice after oral administration of methyl mercury chloride

SummaryWhen methyl mercury chloride was administered orally the amount of mercury excretion with feces of germfree mice was noticeably lower than that of the control mice. Germfree mice excreted 24 percent of the administered mercury within 10 days of administration while the control mice excreted 46 percent. Mercury retention in the organs of germfree mice was slightly higher than in the control mice. These results suggest that the existence of microorganisms in animal intestines are concerned with mercury excretion in the animal body.

Season of birth of schizophrenics in Tokyo, Japan

The monthly distribution of births of 7,960 schizophrenic patients in Tokyo born during the period 1841–1950 was studied in comparison with that of a control population in Tokyo. A spring excess of schizophrenic births were found after 1901 as in previous studies in Western countries. Before 1900, however, there was no significant spring excess. The maximum excess of schizophrenic births occurred in May before 1900 and in April after 1901. The possibility of a shift in the seasonality of schizophrenic births was discussed.

Geographical and secular changes in the seasonal distribution of births

Abstract The long-term variations of seasonal distribution of births in three places distant from one another, Osaka City in Japan, the northern U.S.A. (Massachusetts and Missouri) and Gorlitz in East Germany were investigated, using several kinds of historical records. The birth periods covered were 1755–1975 for Osaka, 1741–1941 for the northern U.S.A. and 1675–1816 for Gorlitz, respectively. The sample size of births before the era of modern vital statistics were 6536 for Osaka, 4132 for northern U.S.A. and 41,507 for Gorlitz, respectively. The birth patterns in the mid-20th century are known to be different among the three areas in the following manner: early spring peak in Japan, fall peak in the U.S.A. and spring peak in Europe. However, this observation of the long-term variation of birth seasonably has revealed that there had been secular changes of the seasonal distribution of births in all three areas, and that a pattern of alternation had been occasionally alike and synchronous. It seems that both the spring-peak and fall-peak birth patterns seen recently in Europe, Asia and the U.S.A. were not fixed for certain geographical locations, and that the interchangeability of these patterns could be seen rather commonly. Based on the various phenomena collected to date about the seasonal distribution of human births, a hypothesis—the epidemic seasonally-infertile factors hypothesis—on the causality of the seasonal distribution of births was put forth.

Epidemic seasonal infertility — a hypothesis for the cause of seasonal variation of births

A hypothesis is proposed to explain the seasonality of births and its variations, that some unrecognized epidemic infertile factors have existed seasonally. In that case, certain women born in a particular low birth rate season must be those who survived these infertile factors in very early stage of their fetal lives. Then in later years, when they become pregnant, they may possibly be immune or different in their susceptibility to these infertile factors. Therefore, mothers born in a particular low birth rate season would tend to bear babies more frequently in that season than the others. To examine this hypothesis, birth records in 1930 of two maternity hospitals in Tokyo were investigated. These years were chosen for a period when seasonality of birth was most prominent in Japan. First babies were excluded to eliminate disturbances by season of marriages and other possible non-biological factors. The results show that among 1038 mothers born in a low birthrate season, May–July, 245 (23.6%) had babies in May–July, while the other mothers had significantly less babies (19.0%, 819/4302, P<0.001) in the same season. This may imply that seasonality of birth may have been influenced by some immunogenic infertile factors epidemic in a particular season.

Twinning rate by month of mother's birth in Japan.

Records of two hospitals and of an association of mothers of twins were analysed for the years 1924-1980, finding a total of 656,109 and 1185 twin births, respectively. Twinning rates were higher in summer or fall, in general, but these seasonal variations occasionally changed within a short period of years, as in 1973-75 in the Association group. The twinning rate was also affected by the month of mothers birth. It was low among the mothers born around May-July in maternities up to 1960, and these mothers did not show seasonal variation of twin births. The unlike-sexed twinning rate of the mothers born in May-July was also lower than that of the other mothers, and constantly low even at higher maternal ages. A possible explanation for these phenomena is discussed.

Season of birth in mental disorders in mental disorders in Tokyo, Japan, by year of admission and age at admission

Seasonal distribution of births of schizophrenics and manic‐depressives born in Tokyo between the years of 1841 and 1940 and first admitted between 1879 and 1973 was examined by year of birth, year of first admission and age at first admission. In both mental disorders, a fall‐excess of births could be seen among those born up to the latter part of the 19th century, after which the distribution changed to show a spring‐excess. The distributional pattern seemed to depend upon both year of birth and year of admission, rather than on age at first admission.

Mercury content in museum and recent specimens of chiroptera in Japan

SummaryThe mercury content of insectivorous Chiroptera caught in 1890, when mercurial pesticides had not yet been in use, and preserved in a museum in alcohol were compared with those caught in 1965–1967 or 1970–1975, during and after the use of mercurial pesticides, and kept frozen. The mercury content of the Chiroptera caught in 1890 was lower than that of those caught during or after the use of mercurial pesticides. Difference in mercury content between bats caught during and after use was not significant.

A study of the sex ratio of first-born according to the mother's month of birth.

SummaryThe male-to-female sex ratio at birth of the first-born babies delivered in Japan to mothers aged 25 years or less was investigated in two groups: a hospital group and a questionnaire group. The sex ratio fluctuated according to their mothers month of birth. Between 1924 and 1928, the sex ratio of the offspring of the mothers born in March-May in both groups was significantly higher than that of the other mothers. We speculate about the relationship between the sex ratio at birth and the mothers month of birth.

The relation between seasonal birth variation and the season of the mother's birth

SummarySeasonal birth variation was investigated in relation to the season of the mothers birth by examining: (1) 21,517 case records of a maternity hospital in Tokyo, Japan, for the period between 1925 and 1960 and (2) 2,348 questionnaires on mothers and their offsprings. In general, the birth rate was the lowest in the May-July season but mothers born in May-July of 1896 through 1915 and February-April of 1916 through 1935 had their births more evenly distributed throughout the year. The less season-sensitive mothers were more fertile than the others. The existence of some epidemic and immunogenic “seasonal infertile factors” is put forward as an explanation for these phenomena.

Twinning Rates and Seasonal Changes in Görlitz, Germany, from 1611 to 1860

Old-age twinning rates were evaluated over a period of 250 years (1611-1860), from 80,256 parish records of baptism in a church office in Görlitz, East Germany. Two periods with high and two periods with low twinning rates were observed. Twinning rates were relatively stable in spring and fall, but varied greatly in winter and summer.