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S Hisamatsu

Publications and source records attributed to S Hisamatsu.

At least 19 recordsLinked to original sources
PubMed1998

Organically-bound 3H concentration in rice around atomic energy facilities.

Rice samples collected around atomic energy facilities in the Tokai area were analyzed for organically-bound 3H (OBT). Measurement results were compared with those for samples from control areas in Japan and the People's Republic of China. OBT concentrations of rice in the Tokai area were found to be 4 times higher than the control area as maximum. Although this relatively high 3H concentration shows the effect of 3H release from the facilities into the environment, the concentration level is comparable with those in the rice sample from a northern interior region of China. The OBT concentration of rice sample from the general environment in interior China was 4.5 times higher than the control area in Japan. The radiation dose from the increasing 3H level is negligible in comparison with that from natural radiation.

Air Pollutants, Radioactive↗
PubMed1997

In vitro activity of the hairpin ribozyme derived from the negative strand of arabis mosaic virus satellite RNA.

The negative strand of the satellite RNA of tobacco ringspot virus [(-)sTRSV] is a self-cleaving RNA, of which self-cleaving domain is called the hairpin ribozyme. The negative strand of the satellite RNA of arabis mosaic virus [(-)sArMV] has been suggested to have a hairpin ribozyme-like secondary structure, and we have previously shown that this hairpin domain of (-)sArMV has ribozyme activity. Here we report characterization of the cleavage reaction of the (-)sArMV hairpin ribozyme. Mutagenesis analyses in a trans-acting system revealed, surprisingly, that the wild-type ribozyme was less active than almost all the other mutant ribozymes tested. In a cis-acting system (self-cleaving reaction), however, the reaction of the RNA containing the wild-type sequence proceeds highly efficiently. This result suggests that the inefficient cleavage of the wild-type substrate in trans-acting system may be due to low efficiency at the substrate-binding step but not at the chemical cleavage step in the reaction. We also constructed a chimeric ribozyme between the catalytic hairpin domain from (-)sArMV and the substrate-binding site from (-)sTRSV. This chimeric ribozyme had the highest activity among the trans-acting hairpin ribozymes tested.

Base Sequence↗
PubMed1995

Tritium concentrations of blood samples collected throughout Japan.

Tritium concentrations were measured for blood samples collected from 20 cities throughout Japan during 1989-1990. The mean 3H concentration was found to be 1.4 +/- 0.4 Bq L-1 and 1.0 +/- 0.4 Bq L-1 (combustion water) for free water 3H and organically-bound 3H, respectively, excluding the abnormally high data of one city. The organically-bound 3H contents clearly depended on the latitudes of sampling locations, although the free water 3H concentrations showed no correlation with the latitudes. Organically-bound 3H is considered to be more suitable than free water 3H as an indicator of long time 3H exposure to human.

Environmental Exposure↗
PubMed1995

Hairpin ribozyme-mediated cleavage of the full-length beta-glucuronidase (GUS) mRNA.

We designed three hairpin ribozymes to cleave Escherichia coli beta-glucuronidase (GUS) mRNA and tested those activities in vitro. One of the ribozymes was designed to form 9 base pairs in total with the target GUS mRNA, and the other two ribozymes had longer substrate binding sites. All ribozymes cleaved the model substrate (100 bases long) at the predicted target site. Two ribozymes containing longer substrate binding sites cleaved the substrate much more efficiently than the other ribozyme containing shorter substrate binding site. Also, the ribozymes with long substrate binding sites had high activity against the full-length GUS mRNA (1.9 kilobases) and maintained the activity even at a low temperature, 26 degrees C, a general growth condition of plant cells. Effects of the substrate binding site length of the ribozyme on cleavage activity are discussed.

Base Composition↗
PubMed1995

Cis and trans reactions of hairpin ribozymes derived from the negative strand of arabis mosaic virus satellite RNA.

We have previously shown that the hairpin ribozyme-like structure of the negative strand of the satellite RNA of arabis mosaic virus [(- )sArMV] has indeed ribozyme activity. However, some mutagenesis analyses revealed surprisingly that the wild type ribozyme was less active than almost all the other mutant ribozymes tested. These results were derived from a trans-acting system. Here we tested this ribozyme activity in a cis-acting system. We show that the (-)s ArMV hairpin ribozyme has different target-site specificities between cis and trans cleavages. The wild type ribozyme has the highest self-cleaving activity among the ribozyme variants tested.

Base Sequence↗
PubMed1993

Acquirement of hairpin ribozyme activity by the long substrate-binding site.

Three hairpin ribozymes were designed to cleave Escherichia coli beta-glucuronidase (GUS) mRNA at a target site. Two of the designed ribozymes (HG10L and HG10L2) had long substrate binding sites and the other (HG10) had short substrate binding site. All three ribozymes cleaved the substrate, and HG10L and HG10L2 cleaved it efficiently. However, HG10 had very low activity. Effect of length of substrate binding site of the ribozyme will be discussed.

Base Sequence↗
PubMed1992

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↗
PubMed1991

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↗
PubMed1989

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↗
PubMed1989

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↗