Ichiro Karai

Appearance of direct-acting mutagenicity of various foodstuffs produced in Japan and Southeast Asia on nitrite treatment

After nitrite treatment, various kinds of pickled vegetables and sun-dried fishes produced in Japan showed direct-acting mutagenicity on Salmonella typhimurium TA100, inducing 1900-18000 revertants/g. Kimchis, sun-dried fishes, sun-dried squid, soy sauces, fish sauces, bean pastes and shrimp paste produced in Korea, the Philippines and Thailand also showed direct-acting mutagenicity after nitrite treatment. All soy sauces and fish sauces tested contained as much tyramine as 17-1020 micrograms/ml, but very low or undetectable amounts of (-)-(1S,3S)- and (-)-(1R,3S)-1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids.

Effect of lead on erythrocyte membranes.

The effect of blood lead on erythrocyte membrane proteins was studied in 28 workers from a scrap lead refining factory and in 18 controls working in railway construction. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of the polypeptides in the erythrocyte membrane showed that bands 3 and 4.1 had significantly decreased while bands 2.3, 6, and 7 had significantly increased in the lead workers compared with the controls. For the lead workers, the correlation coefficients between blood lead and bands 2.3 and 3 were r = 0.545 (p less than 0.01) and r = -0.51 (p less than 0.01) respectively. These results suggest that the decrease in erythrocyte membrane permeability results from a decrease in the membrane transfer protein responsible for band 3.

Studies on osmotic fragility of red blood cells determined with a coil planet centrifuge for workers occupationally exposed to lead.

SummaryIn order to clarify the relationship between lead exposure level and osmotic fragility of red blood cells determined by the coil planet centrifuge method, several clinical laboratory examinations were performed on 27 male workers employed in a scrap lead refining factory using as controls 40 male workers employed in railway construction. The examinations included measurement of red blood cell and reticulocyte counts, hematocrit, MCV, blood and urine lead concentrations, urine coproporphyrin, and urine δ-aminolevulinic acid. The results were:1.Osmotic fragility of red blood cells was lower in lead workers at all three hemolytic points compared with the controls. Significant difference was observed in hemolysis of the maximum point (P < 0.05).2.The red blood cell and reticulocyte counts, hematocrit value and MCV of the lead workers were not significantly different from those of the controls. Values for blood and urine lead, coproporphyrin, and δ-aminolevulinic acid of the lead workers were much higher than those of the controls (P < 0.01).3.In lead workers, close relationships between the osmotic fragility and these laboratory findings were observed: blood lead, r=-0.572, P<0.01; coproporphyrin, r= −0.608, P<0.01; δ-aminolevulinic acid, r= −0.559, P< 0.01; urine lead, r = −0.453, P < 0.05.

An epidemiological study on carbon disulfide angiopathy in a Chinese viscose rayon factory.

SummaryTo assess long-term vascular effects of occupational carbon disulfide (CS2) exposure, we examined 376 exposed and 325 unexposed Chinese workers with a medical and work-history questionnaire, a chest-pain questionnaire, blood pressure and blood cholesterol measurements, routine urinary tests, monochromatic fundus photography and other tests. Data from 354 exposed and 177 age- and sex-matched reference workers were evaluated. Personal exposure monitorings were performed simultaneously with a passive dosimeter using gas chromatography. Monochromatic fundus photography revealed no CS2-retinopathy characterized by microaneurysms and/or small dot hemorrhages, and no effects of CS2 on blood pressure and blood cholesterol were found. These negative results may have been due to the low daily exposure averages, which varied between 0.01 and 12.8, with a mean of 1.5 ppm. The present study suggested that the no-effect level of CS2 exposure on the development of retinopathy was around 2 ppm (8-h time weighted average), and the absence of adverse CS2 effects among the workers studied supported the current standard for occupational CS2 exposure of 10 mg M−3 in China.

Alterations of lipids of the erythrocyte membranes in workers exposed to lead

SummaryChanges in lipids (cholesterol and phospholipids) of the erythrocyte membrane were studied and several laboratory examinations were performed with 25 male workers employed in a scrap lead refining factory using as controls 38 male railway construction workers. The examinations included measurements of erythrocyte count, hematocrit, mean corpuscular volume (MCV), blood and urine lead concentrations, urine coproporphyrin and δ-aminolevulinic acid, membrane cholesterol (CHO) and phospholipids (PL), total and free CHO in plasma, and lecithin cholesterol acyltransferase (LCAT) activity in plasma. The results were:1)Membrane CHO (P < 0.01) and CHO: PL ratio (P < 0.05) of lead workers were higher than those of the controls. But no significant difference was observed in membrane PL between both groups.2)Membrane phosphatidyl choline was higher (P < 0.05) and lysophosphatidyl choline was lower (P < 0.05) in lead workers compared with controls. But no significant difference was observed in membrane sphingomyelin, phosphatidyl serine, and phosphatidyl ethanolamine between both groups.3)Free CHO in plasma was higher (P < 0.05) in lead workers compared with controls. But no significant difference was observed in total CHO in plasma, erythrocyte count, hematocrit, MCV, and LCAT activity between both groups.

Relationships Between Osmotic Fragility of Red Blood Cells and Various Hematologic Data in Workers Exposed to Lead

SummaryThis paper describes relationships between osmotic fragility (OF) of red blood cells and various hematologic data in 32 male workers exposed to lead and 30 controls. The examination included measurements of OF determined by the coil planet centrifuge system, red blood cell (RBC) count, hematocrit, hemoglobin, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), water of RBC, sodium and potassium of RBC, blood and urine lead, urine coproporphyrin, and urine δ-aminolevulinic acid. The results were:1)OF was lower in lead workers at all three hemolytic points compared with the controls (P < 0.05).2)A difference in hemolysis pattern between the two groups was observed (P < 0.05).3)A close relationship was observed in both groups between OF and MCV (P < 0.05), although the results were contrasting. Also a close relationship was observed in lead workers between OF and hematocrit, OF and hemoglobin, OF and MCH, and OF and intracellular potassium (P < 0.05) but not in the controls. In the controls a close relationship was found between OF and RBC (P < 0.05) but this was not observed in the lead workers. No significant relationship was observed in either group between OF and MCHC, OF and intracellular sodium, and OF and intracellular water.4)No difference in RBC, hematocrit, hemoglobin, MCV, MCH, MCHC, and intracellular water, sodium and potassium was observed between both groups.

An increase in the Na+/K+-ATPase activity of erythrocyte membranes in workers employed in a lead refining factory.

To clarify the relationship between erythrocyte Na+/K+-ATPase activity and haematological findings, several clinical laboratory examinations were performed on 31 male workers employed in a scrap lead refining factory and, as controls, 50 male workers employed in railway construction. The results were: (1) Values for erythrocyte Na+/K+-ATPase activity, blood and urine lead, urine delta-aminolaevulinic acid, and urine coproporphyrin of lead workers were significantly higher than those of the controls (p less than 0.01). (2) A strongly positive relationship between blood lead and erythrocyte Na/K-ATPase activity was observed in lead workers (r = 0.473, p less than 0.01). (3) A strongly negative relationship between Na+/K+-ATPase activity and intracellular sodium was observed in both groups (lead workers; r = -0.601, p less than 0.01: controls; r = 0.595, p less than 0.01).

Erythrocyte arginase activity as an indicator of lead exposure.

ABSTRACT A semi-automated method has been developed for the determination of the arginase activity of erythrocytes using dried blood spots, which are easy to prepare on site in a factory for later laboratory analysis. The mean arginase activity of erythrocytes in 49 men occupationally exposed to lead was 62·9 IU/g·Hb (SD, 14·4 IU/g·Hb); in 45 men not exposed to lead the mean was 44·6 IU/g·Hb (SD, 11·6 IU/g·Hb). A significantly higher mean arginase activity was found in the specimens from lead-exposed workers (p < 0·001). The correlation coefficient between blood lead and erythrocyte arginase was r = 0·67 (p < 0·001). The degree of correlation between blood lead and lead indicators including arginase was r = 0·75 for urine δ-aminolaevulinic acid, r = 0·67 for erythrocyte arginase, r = 0·66 for urine lead, and r = 0·63 for coproporphyrin. Erythrocyte arginase showed no significant correlation in the liver function tests, GOT, GPT, and albumin in serum. When 40 μg/100 g of blood lead concentration was fixed as the basic value and 56·2 IU/g·Hb of erythrocyte arginase activity was set as the screening value in lead-exposed workers, the sensitivity and specificity of the arginase test were 0·96 and 0·65, respectively. Thus the validity of the test was calculated to be 1·61. These results show that the arginase level of erythrocytes can be considered to be one of the significant indicators of occupational exposure to lead because it reflects well the dose-response relationship of lead in the human body. Our method allows rapid analysis of erythrocyte arginase and thus should be useful in screening for lead exposure.

Effect of lead in vitro on water metabolism and osmotic fragility of human erythrocytes.

The addition of lead to normal human blood was previously found to cause a decrease in erythrocyte osmotic fragility in vitro. The mechanism of the decreased osmotic fragility caused by lead has not been completely clarified, but the following hypothesis has been proposed. Lead causes a leakage of water from erythrocytes, thus more water can enter the cell before haemolysis occurs. There has been no report, however, of the direct measurement of the intracellular water content of erythrocytes treated with lead. This study has tried to clarify the relation between intracellular water and the osmotic fragility of lead-treated erythrocytes in vitro. The results showed that 0.05 microM/ml of lead decreased the osmotic fragility, the intracellular water content, and intracellular potassium and mean corpuscular volume, increased the plasma water content and trapped water content, and contracted the erythrocyte shape. These changes corresponded well with each other, and close coincidence of the osmotic fragility and the intracellular water content was also observed.

Mechanism of increased osmotic resistance of red cells in workers exposed to lead.

In order to clarify the mechanism of the increased osmotic resistance of red blood cells in lead workers 19 men employed in a lead refining factory and 18 control male workers employed in railway construction were examined for red cell count, haematocrit, MCV, blood and urine lead concentrations, urine coproporphyrin and delta-aminolevulinic acid, osmotic resistance of red cells, lecithin-cholesterol acyltransferase (LCAT) activity in serum, and cholesterol content and cholesterol-to-phospholipid ratio of the red cell membrane. The results were: (1) The osmotic resistance of the red cells (p less than 0.05), cholesterol content of the red cell membrane, blood and urine lead, urine coproporphyrin, and urine delta-ALA concentrations (p less than 0.01) were higher in the lead workers than in the controls. (2) In the lead workers close relationships were observed between the osmotic resistance and the blood lead concentration (r = -0.515, p less than 0.05), osmotic resistance and LCAT activity (r = 0.596, p less than 0.01), and osmotic resistance and cholesterol of the red cell membrane (r = -0.492, p less than 0.05).