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Biomedical subjects

K Tomokuni

Publications and source records attributed to K Tomokuni.

At least 55 records · Page 3Linked to original sources
PubMed1988

Comparison between the fluorometric HPLC method and the conventional method for determining urinary delta-aminolevulinic acid and coproporphyrin as indices of lead exposure.

Fluorometric methods for determining delta-aminolevulinic acid (ALA) and coproporphyrin (CP) in urine have been recently developed by using high-performance liquid chromatography (HPLC). In the present study, urinary ALA and CP in lead-exposed workers were determined with these fluorometric HPLC methods and the conventional methods, and the results obtained were compared. In lead workers with a urinary ALA greater than or equal to 5 mg/l, the values obtained with the fluorometric HPLC method corresponded well with those measured with the conventional colorimetric method. In contrast, in lead workers with ALA less than 5 mg/l, ALA values obtained with the fluorometric HPLC method were lower than those measured with the conventional method, suggesting the possibility of matrix interference in urine. The urinary CP values obtained with the conventional method of Rimington (1971) were higher than those measured with the fluorometric HPLC method, though the correlation was good.

Adult↗
PubMed1988

Relationship between inhibition of erythrocyte pyrimidine 5'-nucleotidase activity and biological response for porphyrin metabolism in workers occupationally exposed to lead.

A rapid determination of erythrocyte pyrimidine 5'-nucleotidase (P5N) activity in lead workers was carried out using a high-performance liquid chromatograph (HPLC). The P5N activity had a good negative correlation with the concentration of lead in blood (PbB) ranging from 16 to 96 micrograms/dl (r = -0.82, n = 77). Further, the P5N was compared with other biological parameters: erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity, erythrocyte protoporphyrin (PROTO), urinary delta-aminolevulinic acid (ALA) and urinary coproporphyrin (COPRO). The correlation coefficients between P5N and ALAD, log PROTO, log ALA, and log COPRO were 0.59, -0.72, -0.65, and -0.61, respectively. On the other hand, the normal value of P5N obtained from 72 healthy subjects was 11.9 +/- 2.1 units; mumol uridine/h/g Hb (mean +/- SD), indicating that the lower limit of 95% confidence interval for normal P5N was about 8 units. When P5N was cut off at less than or equal to 8 units in 77 lead workers, the validity (sensitivity + specificity) for PbB greater than or equal to 40 micrograms/dl, PbB greater than or equal to 60 micrograms/dl, erythrocyte PROTO greater than or equal to 150 micrograms/dl RBC, urinary ALA greater than or equal to 6 mg/l, and urinary COPRO greater than or equal to 150 micrograms/l was 1.66, 1.76, 1.57, 1.68, and 1.60, respectively. From these results, it was confirmed that the erythrocyte P5N test is suitable for the biological monitoring of exposure to lead in a wide range, and its activity is useful in predicting the disturbance of porphyrin metabolism induced by lead.

5'-Nucleotidase↗
PubMed1988

Species difference of urinary excretion of delta-aminolevulinic acid and coproporphyrin in mice and rats exposed to lead.

The urinary excretion of delta-aminolevulinic acid (ALA) was first investigated in mice exposed to lead in the drinking water (500 ppm) for 30 days, and the results were compared with those obtained from rats exposed to lead under the same exposure condition. The result indicated that the level of urinary ALA excretion in lead-exposed mice was much higher than that in lead-exposed rats. This finding suggests a species difference between mice and rats with regard to sensitivity to lead. On the other hand, urinary coproporphyrin (CP) was also determined in rats and mice exposed to lead. The result obtained indicated that the increasing level of urinary CP excretion was higher in rats than in mice, contrary to expectation. The reason for the discrepancy between urinary excretion of ALA and that of CP in rats and mice exposed to lead is, however, unknown.

Aminolevulinic Acid↗
PubMed1988

Comparison of inhibition of erythrocyte pyrimidine 5'-nucleotidase and delta-aminolevulinic acid dehydratase by lead.

The effect of lead on the activities of erythrocyte pyrimidine 5'-nucleotidase (P5N) and delta-aminolevulinic acid dehydratase (ALAD) was investigated in control and lead-exposed workers. The inhibitory effect of lead in vivo and in vitro was more remarkable on the ALAD than on the P5N activity values. It was demonstrated that the pH optimum of both ALAD and P5N in lead workers shifts to the acidic side (nearly pH 6.0) compared to that in control workers.

5'-Nucleotidase↗
PubMed1987

Urinary excretion of 5-hydroxyindoleacetic acid, delta-aminolevulinic acid and coproporphyrin isomers in rats and men exposed to lead.

The urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA), delta-aminolevulinic acid (ALA) and coproporphyrin (CP) isomers (I and III) was investigated in rats and workers exposed to lead. Urinary excretion of 5-HIAA, which is the major metabolite of serotonin, was not influenced by the lead exposure. However, a significant increase in urinary ALA and CP was found in rats and workers exposed to lead. In particular, the urinary excretion of CP-III was markedly increased compared to that of CP-I in rats and workers exposed to lead.

Administration, Oral↗
PubMed1987

Optimized liquid-chromatographic method for fluorometric determination of urinary delta-aminolevulinic acid in workers exposed to lead.

We developed a fluorometric method for determining delta-aminolevulinic acid (ALA) in urine of lead workers. A high-performance liquid chromatograph (HPLC) equipped with a fluorescence HPLC monitor is used. The detection limit for aqueous ALA is 20 micrograms/L (15 pmol of ALA in the 100-microL sample). The working linear range of urinary ALA concentration was 0.1 to 100 mg/L. In 25 lead-exposed workers, ALA values by the present method for urine correlated well with those obtained by a conventional colorimetric method (r = 0.996). The advantage of the present method for micro-determination of urinary ALA is its high sensitivity.

Aminolevulinic Acid↗
PubMed1986

[Improved method for the determination of urinary delta-aminolevulinic acid in lead workers].

An improved method for the determination of urinary delta-aminolevulinic acid (ALA) as an indicator of lead absorption is described. It is a modification of the analytical procedure described by Tomokuni and Ogata in 1972. In the present method, the spot urine from lead-exposed workers which was diluted 3-fold with distilled water beforehand was used as the sample to eliminate as much as possible the urinary matrix interference. In addition, methyl acetoacetate was used as the condensation reagent for ALA-pyrrole, because the color intensity of ALA-pyrrole was higher with the use of methyl acetoacetate than that with ethyl acetoacetate which was used in the original method. The urinary ALA value determined by the present method was similar to that measured using an internal-standard addition method. This method is suitable as a rapid and inexpensive screening procedure for the routine quantitative analysis of urinary ALA.

Aminolevulinic Acid↗