Yuzo Yano

δ-Aminolevulinic acid dehydratase activity in erythrocytes for the evaluation of lead poisoning

The δ-aminolevulinic acid (ALA) dehydratase activity in erythrocytes, the urinary output of ALA, coproporphyrin and lead, and the level of lead in the blood were determined simultaneously in workers exposed to lead poisoning. The decrease of ALA dehydratase activity in lead poisoning (0.263 ± 0.081 μmoles PBG/ml erythrocyte/h as compared with 0.920 ± 0.162 for normal value) correlates very closely (p < 0.01) with the raised blood level of lead and urinary output of ALA, and significantly (p < 0.05) with the duration of exposure to lead. However, poor correlations were found between the decrease in ALA dehydratase activity and the increased urinary outputs of coproporphyrin and lead. Erythrocytes obtained from patients with other neurological and hematological disorders showed normal activity of ALA dehydratase. Reduced glutathione was effective for the recovery of the decreased ALA dehydratase activity in lead-poisoned erythrocytes in vivo. It is concluded that the determination of ALA dehydratase activity in erythrocytes offers an excellent measure for the evaluation of lead poisoning and that administration of reduced glutathione seems to be useful for treating patients with lead-poisoning.

A simple method for the quantitative analysis of urinary delta-aminol evulinic acid to evaluate lead absorption

Wada, O., Toyokawa, K., Urata, G., Yano, Y., and Nakao, K. (1969).Brit. J. industr. Med.,26, 240-243. A simple method for the quantitative analysis of urinary delta-aminolevulinic acid to evaluate lead absorption. A procedure is given for the rapid, quantitative determination of urinary delta-aminolevulinic acid (ALA). Interfering substances are removed by n-butanol extraction. After pyrrole formation with ethyl acetoacetate, Ehrlichs reagent is added to produce the chromophore, which is then extracted with chloroform and measured spectrophotometrically or by comparison of the depth of colour with standard colour solutions. The recoveries were about 91% and the results agreed well with those obtained using ion-exchange column chromatography (r=0·985). This assay is simple, dependable, and suitable for large-scale screening of industrial workers exposed to lead poisoning, because the critical level of urinary ALA (20 mg./l. urine), which indicates dangerous lead absorption, gives a convenient absorbance.

Response to a Low Concentration of Mercury Vapor: Relation to Human Porphyrin Metabolism

The δ-aminolevulinic acid (ALA) dehydratase activity in erythrocytes, the cholinesterase (ChE) activity in serum, the urinary output of ALA, coproporphyrin, protein, and mercury, and the level of reduced glutathione (GSH) in erythrocytes were determined in mercury workers. A significant correlation (P < 0.01) was found between the urinary level of mercury and the values for the decreased activities of ALA dehydratase and ChE, and for the urinary level of coproporphyrin, though their values were not so prominent as in lead poisoning. It was concluded that the response of the biological system in vivo to the metals differs greatly from that in vitro, and that the maximum permissible urinary concentration of mercury would be 200μ g/gm creatinine.

Porphyrias in Japan: Compilation of all cases reported through 2002

The first case of porphyria on record in Japan was a patient with congenital erythropoietic porphyria (CEP) reported by Sato and Takahashi in 1920. Since then until the end of December 2002, 827 cases of porphyrias have been diagnosed from characteristic clinical and/or laboratory findings (463 males, 358 females, and 6 of unknown sex). Essentially all inherited porphyrias have been found in Japan, with the incidences and clinical symptoms generally being similar to those reported for other countries. The male-female ratio was approximately 1:1 for CEP, whereas it was higher for erythropoietic protoporphyria. In contrast, preponderances of female patients exist with acute hepatic porphyrias, such as acute intermittent porphyria (AIP), variegate porphyria (VP), and hereditary coproporphyria (HCP), and with undefined acute porphyria. Although porphyria cutanea tarda (PCT) is believed to be increasing recently in women in other countries because of smoking and the use of contraceptives, it is still by far more prominent in males in Japan than in females. The recent increasing contribution of hepatitis C virus infection to PCT in Japan has also been recognized, but there have been no PCT cases in Japan with HFE gene mutations. Familial occurrence and consanguinity were high for CEP, as expected; however, significant consanguinity was also noted in families where CEP, AIP, HCP, VP, or PCT occurred as a single isolated case without a family history of disease. This survey also revealed that as many as 71% of acute hepatic porphyria cases were initially diagnosed as nonporphyria and later revised or corrected to porphyria, indicating the difficulty of diagnosing porphyria in the absence of specific laboratory testing for por-phyrins and their precursors in urine, stool, plasma, and erythrocyte samples.