Kunihiko Sato

Kyoto University, Kioto, Kyōto, Japan

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Publications (8)17.99 Total impact

  • Hiroyoshi Fujita · Reiko Yamamoto · Kunihiko Sato · Masayuki Ikeda ·
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    ABSTRACT: The interrelationships among purified delta-aminolevulinate dehydratase (ALA-D; EC activity, Pb, and ALA-D concentrations were studied in vitro. The ratio of Pb to the ALA-D subunit, but not the Pb concentration, determined the relative activity of ALA-D, indicating the significance of the amount of ALA-D in studying the mechanism of enzyme inhibition by Pb. To elucidate the in vivo mechanisms of ALA-D regulation, male Wistar rats, 6 months old, were treated with Pb, Zn, and glutathione (GSH) separately or in combination for 130 days. After Pb administration, the amount of ALA-D, as determined by radioimmunoassay, increased in the presence and in the absence of the Zn-GSH pretreatment, even if the enzyme activity were higher (the Zn-GSH-Pb-treated rats) than that of the control. Zn and GSH restored the enzyme activity in vivo synergistically. Since immunochemical study showed the identity of the liver ALA-D with the erythroid ALA-D, the liver and erythroid data were pooled to quantify the interrelationship among ALA-D activity, and Pb, Zn, SH, and the enzyme concentrations. The equation was the relative activity of ALA-D (%) = 0.256.[Pb/ALA-D subunit]2 - 9.56.[Pb/ALA-D subunit] - 0.000281.[square root Zn.SH/ALA-D subunit]2 + 0.0898..[square root Zn.SH/ALA-D subunit] + 33.6 (multiple correlation coefficient = 0.909, n = 108, p less than 0.01). The result indicated that 83% of the in vivo regulation of ALA-D activity is explained when the four factors, Pb, Zn, SH, and ALA-D concentrations, are considered in combination.
    Toxicology and Applied Pharmacology 02/1985; 77(1):66-75. DOI:10.1016/0041-008X(85)90268-6 · 3.71 Impact Factor
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    ABSTRACT: Personal monitoring of exposure to tetrachloroethylene (TETRA) with carbon felt dosimeters and analyses of urine for total trichloro-compounds (TTC) were carried out in two groups of workers (36 males and 25 females), one group (20 males and 19 females) in dry-cleaning workshops and the other (16 males and 6 females) engaged in the removal of glue from silk cloth. Comparison of the urinary TTC levels with TETRA in the environment revealed that, while the metabolite levels increased essentially linear to TETRA concentrations up to 100 ppm, leveling off was apparent in the metabolite excretion when the exposure to TETRA was more intense (e.g. more than 100 ppm), indicating that the capacity of humans to metabolize TETRA is rather limited, as previously discussed. From the set of the data thus obtained, screening levels of 30 and 61 mg TTC (as TCA)/l urine as the lower 95% confidence limits for a group mean were calculated for the biological monitoring, by means of urinalysis, of exposure to TETRA at 50 and 100 ppm (TWA), respectively. A tentative calculation with additional exhaled-air analyses indicated that, at the end of an 8-h shift with exposure to TETRA at 50 ppm (TWA), 38% of the TETRA absorbed through the lungs would be exhaled unchanged and less than 2% would be metabolized to be excreted into the urine, while the rest would remain in the body to be eliminated later.
    International Archives of Occupational and Environmental Health 11/1983; 51(4):381-390. DOI:10.1007/BF00378352 · 2.20 Impact Factor
  • Kunihiko Sato · Hiroyoshi Fujita · Shunen Inui · Masayuki Ikeda ·
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    ABSTRACT: A 7-year follow-up survey on 53 workers was carried out in a lead storage battery factory to evaluate the significance of urinary delta-aminolevulinic acid (ALA) and blood lead in a work environment where lead in the air was considered to be about or less than the current occupational exposure limit. While lead in the blood and ALA in the urine had a good correlation to each other cross-sectionally as well as longitudinally, geometric means of lead concentrations in the workroom air samples which were collected following grid sampling strategy, did not correlate with ALA in urine significantly. On the contrary, the semiannual production of batteries significantly correlated with changes in mean ALA in urine. The questionnaire survey proved that the prolongation in work hours, lead to an increase in the mean ALA in urine as well as a higher incidence of higher-than-normal urinary ALA. The results clearly demonstrated the importance of the biological indicators, such as lead in blood and urinary ALA, as well as the necessity of paying attention to non-industrial hygiene factors, such as the production rate of batteries and the length of the daily shift, for the protection of the workers' health when lead in the air is moderate.
    International Archives of Occupational and Environmental Health 02/1983; 52(1):25-32. DOI:10.1007/BF00380604 · 2.20 Impact Factor
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    ABSTRACT: Head space gas chromatography (GC) was applied to measure methyl ethyl ketone (MEK) in urine from 62 MEK-exposed male workers, whose individual intensity of exposure to MEK was monitored utilizing the carbon felt dosimeter. The urinary MEK level increased rapidly to reach a plateau in the first quarter of the daily 8-h work, while very little MEK was detected in the preshift urine. When the MEK levels in the urine at the end of the shift were compared with the afternoon MEK-TWA values, the uncorrected MEK in urine correlated best with MEK in air (r=0.774, n=62), while correction for creatinine gave a comparable result and the correlation was poorer when corrected for a specific gravity of urine or for the lapse of time after preceding passage of urine. Balance of MEK absorption via inhalation and MEK excretion into urine revealed that only 0.1% of MEK absorbed will be excreted unchanged into urine. Wider application of head space GC is discussed for the analysis of unmetabolized solvents in urine.
    International Archives of Occupational and Environmental Health 05/1982; 50(2):131-137. DOI:10.1007/BF00378075 · 2.20 Impact Factor
  • Hiroyoshi Fujita · Kunihiko Sato · Masayuki Ikeda ·
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    ABSTRACT: Differences in the amount of δ-aminolevulinic acid dehydratase (ALA-D) as determined by radioimmunoassay, hematology, and body weight increase were observed between infant and adult rats after lead treatment. Administration of the lead through drinking-water containing 25 mM lead acetate resulted in an increase in blood lead contents in both infant and adult rats to almost the same degree. The influence of lead on the body weight, however, was significant only in infant rats, with a reduction in both weight to 70% of the controls. The increase in ALA-D content of peripheral erythrocytes of infant rats (about 4 times that of the controls) was more marked than that of adult rats (about twice that of the controls). A possible explanation of this difference is that, in the case of adult rats, the increase in the amount of ALA-D is due to increased synthesis of the enzyme in bone marrow cells, while the increase of the enzyme in infant rats results from anemia with increased numbers of young erythrocytes in the peripheral blood in addition to the increased synthesis of ALA-D. The findings suggest that rapid growth during the infant stage prevents the hematological compensation for the effect of lead, resulting in anemia and marked increase in the amount of ALA-D. It was found in the present study that the European Standardized Method is not suitable for ALA-D assay in exposure of rats to lead.
    Industrial Health 02/1982; 20(3):199-207. DOI:10.2486/indhealth.20.199 · 1.12 Impact Factor
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    Hiroyoshi Fujita · Kunihiko Sato · Seiyo Sano ·
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    ABSTRACT: The amount of ALA-D in human erythrocytes was determined directly by radioimmunoassay or calculated from the restored activity assayed in the presence of zinc and dithiothreitol, and a good correlation was observed between the RIA-based and the restored activity-based amounts. The RIA-based amount of ALA-D in the blood of 10 normal individuals (blood lead levels of 5.6 +/- 2.3 micrograms/ml: mean +/- SD) and 19 lead-exposed workers (blood lead levels of 41.2 +/- 10.2 micrograms/100 ml) was 54.1 +/- 11.8 microgram/ml blood and 92.3 +/- 20.6 micrograms/ml blood, respectively, indicating an apparent increase of the enzyme amount in lead-exposed workers. A significant increase in the amount of erythrocyte ALA-D calculated from the restored activity in lead-exposed workers was observed even in the low blood lead level of 10-20 microgram/100 ml, resulting in the range of blood lead level 20-40 microgram/100 ml. No significant difference was observed in hematocrit and hemoglobin content between lead-exposed and non-exposed groups. These observations suggested that the increase of erythrocyte ALA-D in lead exposure was not due to anemia, which might result in the increase of young erythrocytes in peripheral blood. This increase in the amount of ALA-D in human erythrocytes might be a result of the function to overcome the inhibition of the enzyme in bone marrow cells during lead exposure, and these findings may throw light on the danger to human health of low-level lead toxicity.
    International Archives of Occupational and Environmental Health 02/1982; 50(3):287-97. DOI:10.1007/BF00378090 · 2.20 Impact Factor

  • Industrial Health 02/1981; 19(1):37-45. DOI:10.2486/indhealth.19.37 · 1.12 Impact Factor
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    ABSTRACT: Lymphocytes from 10 factory workers, who had been exposed to tetrachloroethylene for 3 months to 18 years, were examined for possible chromosome aberration, increased sister chromatid exchanges, and modified cell-cycle kinetics. The exposure intensity was such that the workroom air analyses disclosed 92 ppm as a geometric mean in the workshops for Group 1 (6 workers from degreasing workshops), but was in the range of 10 to 40 ppm for Group 2 (4 workers from a support department). Urinalyses for total trichloro-compounds showed 50.7 and 19.0 mg (as trichloroacetic acid)/l as a geometric mean in Group 1 and 2, respectively. Cytogenetic and cytokinetic studies did not reveal any significant dose-related changes in chromosome aberrations (either numerical or structural), SCEs rate, the proportion of M2 + M3 metaphases or mitotic index, compared with concurrent controls. Mitomycin C treatment also failed to induce any difference between exposed workers and controls.
    Toxicology Letters 04/1980; 5(3-4-5):251-256. DOI:10.1016/0378-4274(80)90068-5 · 3.26 Impact Factor