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Biomedical subjects

S Hisamatsu

Publications and source records attributed to S Hisamatsu.

At least 37 records · Page 2Linked to original sources

Tritium concentration in Akita City diet.

The 3H concentration in the diet of residents in Akita City, northern Japan, during autumn of 1987 and winter of 1988 was analyzed. Results were similar to those for spring and summer samples previously reported. No significant seasonal change of 3H concentration was observed. A simple model was constructed for estimating the mean residence time for organically-bound 3H in diet. However, more data about diet in the 1960s or 1970s are necessary for the estimation.

Diet↗

Tritium concentration in unpolished rice.

Inoue and Iwakura recently reported that the specific activity ratio of organically-bound 3H to free water 3H in polished rice samples collected in Japan and China was lower than unity. Their paper was the first to report the systematic apparent elimination of 3H for incorporation to organically-bound form in samples collected from the general environment. To confirm their result, seven unpolished rice samples obtained just after harvesting were analyzed for 3H. The mean specific activity ratio of organically-bound 3H to free water 3H was found to be 0.57, somewhat lower than the data by Inoue and Iwakura. This small difference may be caused by the different sampling years and/or the possible replacement of free water by atmospheric water vapor after harvesting.

Food Contamination, Radioactive↗

Fallout 3H in human tissue at Akita, Japan.

The 3H concentration in Japanese human tissue samples is reported in this paper. Four brain, 10 liver, and nine lung samples from 11 cases were collected from Akita Prefecture in northern Japan from January to July 1986. The median of free-water 3H concentration was similar in these tissues and agreed well with the concentrations in the diet, including tap water. The median specific activity ratio of tissue-bound 3H to free-water 3H was 1.1 and was slightly lower than that in the diet. The specific activity ratio was also lower than that reported in the United States and significantly lower than in Italy.

Brain Chemistry↗

Further study on fallout 3H ingestion in Akita, Japan.

To study fallout 3H ingestion in Japan, 16 separate food-group samples were collected from Akita City in northern Japan during early summer and late autumn in 1986. Furthermore, total diet samples which are duplicate composite food samples consumed by five or six persons for a period of 1 d were also obtained in Akita City. The 3H concentration in free water and that in a tissue-bound form were determined separately. Seasonal changes of 3H concentration in the food samples and the total diet samples were not found clearly. The average 3H concentration in the free water including tap water was 1.6 Bq L-1. The mean ratio of specific activity of tissue-bound 3H to that of 3H in free water was found to be 1.2. The average total 3H ingestion was estimated to be 4.0 Bq d-1, while the proportion of tissue-bound form 3H ingestion to total 3H ingestion was 11%. Cereal was the greatest contributing food group to ingestion of tissue-bound 3H. These findings were consistent with our previous results for food samples collected in 1985.

Food Contamination, Radioactive↗

Geographical distribution of cerebrovascular disease mortality and food intakes in Japan.

The present study focuses on an analysis of the relationship between cerebrovascular disease mortality and food intake. For this purpose, standardized mortality ratios(SMRs) from cerebrovascular disease were calculated for 3341 basic administrative units (wards, cities, towns and villages) between 1969 and 1978 in Japan. The major nutrient intakes and 30 selected food items were obtained from the 1974-1974 Ministry of Health and Welfare, National Nutrition Surveys in 1040 randomly sampled census tracts in 600 areas (18% of the nation). Our analysis demonstrates that the geographical pattern of cerebrovascular disease SMRs in Japan vary from higher in East Japan to lower in the West, and higher in the less urbanized areas, and lower in the more urban ones. Foods positively associated with cerebrovascular disease were rice and other starchy foods, pork, algae (seaweed), and salty foods such as miso (soybean paste), pickled vegetables, soy sauce and salted fish. All of these foods, with the exception of pork, are part of the traditional Japanese diet. On the contrary, mortality was negatively associated with intakes of wheat, butter and margarine, beef and eggs, items considered to be representative of a European diet. Using a stepwise multiple regression analysis, miso and salted fish were selected as positive, and beef and eggs as negative correlates of cerebrovascular disease mortality. According to these results, it is suggested that these four foods are useful as negative and positive indicators of improvement in dietary intakes as related to the reduction in the occurrence of cerebrovascular disease.

Animals↗

Ingestion intake of fallout Pu in Japan.

Ingestion intakes of fallout Pu throughout Japan in the 1959-1962 and 1978-1980 periods were measured by analyzing composite samples of each foodstuff or duplicate composite food samples consumed by five persons for a period of 1 d. Cumulative ingestion intake in Tokyo for the period from 1954-1980 was estimated by regression analysis. The cumulative ingestion intake, calculated by simple regression analysis between the natural log of the intake and that of annual fallout deposition of Pu, was estimated to be 450 pCi. Calculated by a multiple regression analysis, including the natural log of annual fallout deposition rates for a previous year as an additional independent variable, it was estimated to be 600 pCi. Considering in combination an ingestion intake, the value of which is calculated by the multiple regression analysis; an absorption ratio from the gastrointestinal tract of 0.001 (a recently reported value for low-level soluble Pu independent of chemical form); and the metabolic model in ICRP Publication 30, it is possible to estimate that the contribution of ingestion intake to liver and bone burden would be approximately 30%.

Body Burden↗

Fallout 3H ingestion in Akita, Japan.

To study fallout 3H ingestion in Japan, 16 separate food group samples were collected from Akita during 1985. The 3H concentration in free water and that in a tissue-bound form were determined separately. The average 3H concentration in the tissue-bound form was 2.2 Bq L-1, 1.7 times higher than in the free water of the food. The ingestions of 3H in the tissue-bound form and as free water in the diet were 0.60 Bq d-1 and 1.0 Bq d-1, respectively. Cereals represented the food group that contributed the most to the ingestion of tissue-bound 3H. Total 3H ingestion was estimated to be 4.1 Bq d-1. The contribution of the tissue-bound form to the total ingestion was 15%, considerably lower than reported for Italian diets. The ratio of 3H ingestion in the tissue-bound form to the free water form in the diet was similar to the ratio reported for New York City.

Diet↗

Effect of gavaged chemical form of 241Am on its retention in mice.

The retention of 241Am in mice 48 h after administration by gavage is reported here. The 241Am was given to mice in the form of either 241Am nitrate or 241Am citrate. The 241Am was also injected into rats in the same form. The homogenized livers of those rats were subsequently administered by gavage to another group of mice. The retention of 241Am citrate was 1.5 X 10(-2)% of the original dose and was the highest among the compounds examined. The retention of biologically incorporated 241Am into the liver as 241Am nitrate and as 241Am citrate was 2.4 X 10(-3) and 2.6 X 10(-3)%, respectively, and was similar to the retention of 241Am nitrate, which was 2.8 X 10(-3)%. The ratio of the retention in the carcass to that in the liver for the 241Am citrate was lower than that of the 241Am nitrate and the biologically incorporated 241Am. This difference indicates that the distribution of 241Am in the animal body depends on the chemical form administered. The retention of liver-incorporated 241Am as citrate after autolysis of the liver is similar to that of fresh liver-incorporated 241Am citrate.

Americium↗

Concentration of fallout plutonium in tissues of Japanese who died during 1980-1984.

The concentrations of fallout 239 + 240Pu in various body tissues of subjects who were born before 1941 and who died in Akita and Niigata Prefectures in Japan during 1980-1984 are reported. The median concentrations in vertebrae, sternum, liver, lung, spleen, and kidney were 0.21, 0.08, 0.62, 0.11, 0.08, 0.03 pCi/kg wet weight, respectively. The concentration levels in vertebrae were approximately three times higher than in the sternum. No significant correlation between the concentration in the various tissues and age at the time of death was observed. No differences in the concentration levels in liver and lung were observed between the sexes. Correlation between the concentration in liver and that in lung was not significant. The concentration in liver was similar to that estimated from the ICRP 30 model. However, the concentration in lung was considerably higher than the estimated value. This difference may be caused by the pulmonary lymph nodes contained in the present lung samples. To obtain the average concentration of plutonium in the entire skeleton, further information regarding the macrodistribution of plutonium is required.

Adult↗

Fallout Pu in the Japanese diet.

The ingestion of fallout Pu from seven or six separate food groups collected in Japan during 1962 and 1983-84 are reported. The contribution of ingested Pu from algae was the highest among the food groups studied: approximately 60% of the total ingested Pu during 1962, and 74% in 1983-84. The contribution from whole marine products, i.e. algae and fish/shellfish, was approximately 70% of the total Pu ingested in 1962, and more than 90% in 1983-84. The higher Japanese ingestion rate than that of the United States is attributable to the higher consumption rate of marine food products in Japan. Also reported in this paper are the ingestion rate for 137Cs from fallout through the same food groups, and the concentration of Pu and other radioactive nuclides in specific individual foodstuffs and algae samples.

Food Contamination, Radioactive↗

Placental transfer and distribution of 241Am in the rat.

The placental transfer and distribution of 241Am in the feto-placental system were studied in pregnant rats. Rats were injected intravenously with 241Am citrate at 15 or 18 days of gestation. Groups injected at 15 days of gestation were sacrificed 2, 24, 48, or 120 hr after injection, and the group injected at 18 days was sacrificed 24 hr after. The radioactivities of 241Am in fetus, fetal membrane, and placenta were determined, and its distribution in the feto-placental system was investigated by high-speed autoradiography using a silver-activated zinc sulfide-coated membrane as an intensifying screen. The deposition of 241Am in feto-placental units increased with the number of days of gestation. Results of autoradiography revealed that major deposition sites of 241Am in the fetus are the skeleton and liver. Heavy deposition of 241Am in the yolk sac splanchnopleure and its existence in the exocoelom strongly suggest that the yolk sac placenta plays an important role in the placental transfer of this nuclide.

Americium↗