Aging and activity of 5-aminolevulinate hydrolyase in the blood of humans and rats

Activity of 5-aminolevulinate hydrolyase (delta-aminolevulinic acid dehydrase, ALAD, EC 4.2.1.24) in the blood was determined in relation to age in humans and rats, and the following findings were obtained: (1) In the group which consisted of 47 women (mean age 46, ranged 24 to 62 years) living in a rural district, where the atmospheric lead concentration was 0.5 micron/m3, a significant negative correlation between ALAD activity and age was observed statistically (r = -0.54). However, in the group which consisted of 53 women of similar age group living in an urban district, where the atmospheric lead concentration was 1.9 microng/m3, showed a lower level of the ALAD activity than that of the former group and no correlation was found r = -0.01) between ALAD activity and age. (2) The ALAD activity of intact rats showed a decrease with age. The decrease proceeds rapidly within 8 weeks of age and becomes stable after reaching 25 weeks of age or 300 g of body weight. The value of the activity after 25 weeks of age was about one tenth of that at 5 weeks of age or 100 to 130 g of body weight. (3) Fifteen intact rats weighing 240 to 705 g were divided into three groups according to their body weight and were injected with lead acetate solution equivalent to 1 mg Pb/kg intraperitoneally in order to examine the sensitivity to lead in rats that have variation of ALAD activity by age or by body weight. The ALAD activity of these rats fell to the same level in all groups independently of the activity or the body weight before injection.

Blood lead and erythrocyte delta-aminolevulinic acid dehydratase levels in Manchester taxi drivers

Among 40 Manchester taxi drivers the mean blood lead was 1.10 mumol/1 (22.8 mug per 100 ml). The mean erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity among 34 of them was 30.1 units. No significant association was found between the blood lead levels and erythrocyte ALAD activity in these 34 men. No significant association was found between either blood lead elvels or erythrocyte ALAD activity and duration of service or weekly mileage as a taxi driver or with drinking or smoking habits, or age. The mean blood lead of those with homes in the north east quadrant of the city was higher than of those living elsewhere but the difference was not statistically significant. Although there was no correlation between blood lead levels and the source of domestic water, the mean blood lead of those with lead domestic plumbing was appreciably higher than the level of those with copper plumbing. There was no indication that, by virtue of their occupation, the taxi drivers were liable to greater lead absorption than their fellow-citizens.

Heavy metal levels and delta-amino-levulinic acid dehydrase levels in peripheral polyneuropathy

On the basis of assay of heavy metals in whole blood (lead, cadimum, chromium, copper, nickel and manganese) and delta-amino-levulinic-acid dehydrase (ALA-D) and ALA in urine in a normal Danish population, the levels of these clinco-chemical factors were assayed in 23 patients with peripheral neuropathy of unknown etiology. All patients studied showed electro-physiological sign of denervation and/or reduced motor or sensoric nerve conduction velocity. Cadmium and manganese were never found to be increased. In all but four patients, an increase of one or more heavy metals was found. Ten patients showed raised levels of two or more metals, the dominant metal being lead (10 cases), nine patients showed increased in chromium. A significant corrleation was found between increasing lead levels and decreasing ALA-D activity. Although normal concentrations of manganese were found, correlation analysis revealed a significant correlation between increased manganese and decreased ALA-D. The raised values of heavy metals could not be traced to occupational or other exposure to heavy metals and the increased values were not related to tobacco consumption. The findings are discussed in relation to known data on neuropathy and the results seem to indicate a multifactorial patholgenesis of the disease. Among factors contributing to the precipitation of the syndrome may be raised levels of heavy metals.

Activity of erythrocyte delta-aminolevulinic acid dehydrase and its change by heat treatment as indices of lead exposure

The effect of heat treatment on erythrocyte delta-aminolevulinic acid dehydrase (ALAD) activity in the blood of human subjects was examined in relation to their lead exposure.

Effect of ethanol and zinc on ALA-dehydratase activity in red blood cells

Subcutaneous injection of zinc as sulphate to rats activates sigma-aminolaevulinic acid dehydratase (ALA-D) in red blood cells within few days of injection. This activation counteracts the inhibitory effect of orally administered ethanol.

Blood lead levels and erythrocyte delta-amino-levulinic acid dehydratase activity of selected population groups in Helsinki

The levels of lead in the blood of the adult general population in Helsinki were determined during the period May 1972-June 1973. The possibility of occupational exposure to lead was scrupulously excluded.As control groups rural population groups were sampled in the commune of Pertunmaa and the communes of Haapajärvi and Pyhäjärvi. The concentrations of air-suspended particulate lead were studied during 1 year in Helsinki and Pertunmaa; the population groups were sampled from the geographical vicinity of the sampling sites. Care was taken to ensure the accuracy and precision of the analytical methods at experienced laboratories. The annual mean concentration of lead in air in Helsinki ranged from 0.43 to 1.32 mug/m3. The corresponding mean at the rural sampling site (Pertunmaa) was 0.025 mug/m3. From an international standpoint, the Pb-B levels were low. The highest mean Pb-B value in groups of the general population occurred in the rural male group (12.3 mug/100 ml); and the lowest, in the female respondents of the Pertunmaa survey (7.9 mug/100 ml). A group comprising 86 male streetsweepers from Helsinki displayed a Pb-B mean value of 13.3 mug/100 ml, and 28 traffic-directing policemen displayed a mean of 13.5 mug/100 ml, a finding indicating a slight increase in lead absorption. No effect on the Pb-B levels of traffic alone was detectalbe within the general population; thus no statistically significant differences were found between downtown and rural or suburban Pb-B levels. The observation that the Pohjois-Haaga suburbanites disclosed higher Pb-B levels. The observation that the Pohjois-Haaga suburbanites disclosed higher Pb-B levels than did other suburbanites indicates that factors other than traffic should be borne in mind in the assessment of the effect of traffic on lead absorption. The delta-amino-levulinic acid dehydratase (ALAD) assay proved useful and reliable in the discrimination between separate groups whose Pb-B levels differed to a small but measurable extent. The negative correlation between Pb-B and ALAD activity was found to prevail at a statistically significant level still at Pb-B levels of 10 mug/100 ml or lower.

Erythrocyte delta-aminolevulinic acid dehydrase changes in the preruminant calf

Sixteen preruminant, male Holstein calves were tested for erythrocyte delta-aminolevulinic acid dehydrase activity, hemoglobin and erythrocyte count in blood samples taken weekly during the first 13 wk of life. delta-Aminolevulinic acid dehydrase showed a continual increase in activity beginning at wk 3 to a maximal activity at wk 9. Hemoglobin content was decreased by wk 5 and erythrocyte count was reduced by wk 6. delta-Aminolevulinic acid dehydrase enzyme activities increased with age corresponding to changes in hemoglobin and erythrocyte count during early postnatal development of the preruminant calf.

Relationship between activation of delta-aminolevulinic acid dehydratase by heating and blood lead level

Both blood lead and erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) activity were determined for workers with and without an occupational lead exposure. In workers occupationally exposed to lead, it was demonstrated that the erythrocyte ALA-D is markedly activated by heating the hemolysate at 60 degrees C for 5 min and there is a good positive correlation between the ratio of heated to nonheated ALA-D activity and the blood lead level (r=0.799). In addition, by heating the hemolsyate, the ALA-D activity of the lead-exposed workers appears to be returned into the normal range regardless of the extent of lead absorption. However, in normal workers without the occupational lead exposure, no significant correlation was found between the ratio of heated to nonheated ALA-D activity and the blood head level, although the normal ALA-D also can be slightly activated by heating the hemolysate at 60 degrees C for 5 min.

[Blood levels of lead and erythrocyte ALA-dehydrase in 200 employees of a Turin metallurgical plant. Analysis of variables connected with alcohol drinking and smoking habits]

The relationships between blood value of Pb and activity of Ala-dehydrase erythrocyte enzyme were studied in relation to the following variables: age, activity, residence, smoking habits, drinking habits. 200 adults, subdividable into occupationally exposed were examined. The data obtained showed a relationship between smoking and Aladehydrase; a relationship was also found to exist between alcohol and blood Pb and inhibition of Ala-dehydrase activity.

Fluorometric determination of delta-aminolaevulinate dehydratase activity in human erythrocytes as an index to lead exposure

We describe a fluorometric method for determining delta-aminolaevulinate dehydratase (EC 4.2.1.24) activity in human erythrocytes and compare it with the existing colorimetric method. Incubation conditions are identical. In the proposed method, the porphobilinogen formed during incubation is converted to a stable and highly fluorescent uroporphyrin by heating for 20 min at 93 degrees C in an acidic medium in the presence of air. The correlation between results by the two methods was good (r = 0.89). We found a good negative correlation between the activity of the enzyme and the concentration of circulating lead with both methods (r = -0.61 for present method and -0.59 for colorimetric method) for groups of persons subjected to various degrees of lead exposure. Our method is more sensitive and accurate, requires less sample, and the fluorescence is more stable than is the color in the colorimetric method.

Effect of zinc and cadmium on delta-aminolevulinate dehydratase of red blood cells in protecting against enzyme losses during storage

The effect of zinc and cadmium on delta-aminolevulinate dehydratase of bovine erythrocytes stored at -30 degrees C for different times was determined. The results show a. storage of erythrocytes leads to an enhancement of the enzyme activity, which after six weeks is 165% (500 muM ZnCl2) respectively 220% (100 muM CdCl2) for red blood cells of calves, and after four weeks in 420% respectively 450% (same concentrations) for red blood cells of adult cattle, b. the older the samples are, the higher is the metal concentrations, needed for activation.

Erythrocyte delta-aminolevulinic acid dehydratase activity as a measure of lead exposure

The measurement of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) activity has been found to be a useful guide to lead exposure for screening purposes. The pH of the test should be well-controlled for adequate clinical interpretation. False-normal tests are rare even with iron-deficiency anemia or macrocytosis. Recent transfusion and recent bleeding or hemolysis with reticulocytosis tend to invalidate the test. ALA-D activity above 600 International Units effectively excludes significant lead exposure and eliminates the need for further testing. ALA-D activity is maximally depressed at a red cell lead concentration of 200 mug per 100 ml. When activity is moderately depressed, interpretation is difficult and the urinary excretion of lead after the administration of a chelating agent is usually required to differentiate the degree and significance of lead exposure.

Intraspecific red cell enzyme variation in the pigtailed macaque (Macaca nemestrina)

The erythrocytes of 350 pigtailed macaques (Macaca nemestrina) were examined for electrophoretic variation of hemoglobin and 26 enzymes. Seven enzymes showed variation in more than 1% of individuals: phosphoglucose isomerase, phosphoglucomutase-1, soluble NADP-dependent isocitric dehydrogenase, peptidase A, peptidase C, 2,3-diphosphoglycerate mutase, and acid phosphatase. Variation with lesser frequency was found in soluble glutamic-oxalacetic transaminase, phosphoglycerate kinase, lactic dehydrogenase, and hemoglobin. Only eight samples were tested for esterase D, and one of these had a variant phenotype. Enzymes with no clear variation were adenylate kinase, adenosine deaminase, phosphofructokinase, hexokinase, pyruvate kinase, glyceraldehyde 3-phosphate dehydrogenase, aldolase, phosphoglycerate mutase, phosphopyruvate hydratase (enolase), phosphoglucomutase-3, and superoxide dismutase. There was father-to-son transmission of PGI, PGM-1, peptidase C, 6PGD, 2,3-DPGAM, NADP-ICD, and acid phosphatase variants, suggesting that these loci are autosomal as in man.

Different behaviors of erythrocyte delta-aminolevulinic acid dehydratase. A comparison study between lead workers and normals

Different characteristics of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D1) between the workers with the history of occupational lead exposure and normals are described. In the blood of lead workers, when the hemolysates are heated at 60 C for five minutes, the activity of the erythrocytes ALA-D increases up to about 3.6-fold of an initial level, and as a result of heating the optimum in pH-activity curvee changes from pH 6.0 to pH 6.6, which is similar to the optimum pH of normal ALA-D. On the contrary, in normal blood, the optimum in the pH-activity curve is but little changed, even though the erythrocyte ALA-D activity is increased up to about 1.3-fold of the initial level by heating the hemolysates at 60 C for five minutes.

Recovery of blood lead concentration and of red cell 8-aminolevulinic acid dehydrase activity in dogs following return to normal diets after 75 weeks of lead feeding

Blood lead concentration and red cell delta-aminolevulinic acid dehydrase (ALAD) activity were determined at intervals for eight months after symptom-free dogs, which had received 100 ppm or 500-1000 ppm of lead, by weight, in their diets for 75 1/2 weeks, were returned to a lead-free diet. Statistical treatment of the data disclosed a linear relationship between the logarithm of blood lead concentration or of ALAD activity and the logarithm of time (experimental week) during the recovery period. The calculated regressions predict that recovery of ALAD will occur before recovery of the blood lead concentration. Predicted recovery times depend on the levels selected as those which must be attained for recovery to be complete, as well as on the dosage of lead. The logarithm of the slope of the ALAD recovery regression of the individual dog has a linear relation to the percentage reduction in ALAD due to the lead, the regression accounting for 92% of the variance in the recovery rates. The slope of the blood lead recovery regression has a linear relation to the increase in blood lead for the dogs which received the low lead diet, but not for those which received the high lead diet.

[Investigations on the combined effect of zinc and lead (author's transl)]

The effect of zinc and the combined effect of zinc and lead on the Ala-D of the erythrocytes were experimentally followed in vivo and vitro. It was demonstrated that the zinc effect on the Ala-D is a function of the zinc-concentrate in blood. It was hence traced that ZnCl2 dosis up to 500 mug/ml blood raises the activity of Ala-D. Higher levels of ZnCl2 on other side leads to supression of the Ala-D activity. The experiments demonstrated further zinc exerts a dosis dependent antagonistic effect on the lead suppression of the Ala-D. Possible explanations of the effect of zinc on the Ala-D, and the antagonistic zinc effect after lead applications are still in discussion.

Blood cell gamma-aminolevulinic acid dehydratase activity in humans exposed to methylmercury

The gamma-aminolevulinic acid dehydratase (ALA-D) activity in blood cells was studied in 15 subjects exposed to methylmercury through consumption of contaminated fish and 19 "unexposed" subjects with a similar sex and age distribution. The exposed subjects had a mean mercury level of 120 (range 15-370) ng/g blood cells while the controls had 9 (range 4-15) ng/g. Both groups had the same mean level of lead in whole blood (10+/-1 mug/100 ml). ALA-D activity decreased statistically significantly as both mercury and lead levels in the blood cells increased.

Metabolism of prostaglandins E, A, and C in serum

Three prostaglandin-metabolizing enzymes were detected in human serum. One enzyme was a dehydrase that converted prostaglandin E to prostaglandin A, the second was a prostaglandin A isomerase that converted prostaglandin A to prostaglandin C and the third was a prostaglandin C isomerase that converted prostaglandin C to prostaglandin B. All three were inactivated by sulfhydryl blocking agents. In human serum, only prostaglandin C isomerase had high activity, whereas the two other enzymes had very low activity. In rabbit serum both isomerases were very active, but dehydrase activity could not be detected. Prostaglandin C isomerase activity was also found in crystallized human serum albumin and rabbit serum albumin.

Comparative study of effect of inorganic lead and cadmium on blood delta-aminolevulinate dehydratase in man

Lauwerys, R. R., Buchet, J.-P., and Roels, H. A. (1973).British Journal of Industrial Medicine,30, 359-364. Comparative study of effect of inorganic lead and cadmium on blood δ-aminolevulinate dehydratase in man. δ-Aminolevulinate dehydratase (ALA¹-D) of red blood cells, lead concentration in blood (Pb-B) and in urine (Pb-U), cadmium concentration in blood (Cd-B) and in urine (Cd-U), and ALA in urine (ALA-U) were measured in 77 workers occupationally exposed to cadmium, and in 73 control workers. An excellent negative correlation was found between log ALA-D and Pb-B (r = - 0·660) or Pb-U (r = - 0·501), but no significant correlation was found between Cd-B and log ALA-D activity. Unlike ALA-D, ALA-U is not correlated with Pb and Pb-U in the `normal' range of Pb concentration investigated. Mean ALA-D activity in smokers is lower than in nonsmokers, and this is probably related to the fact that a higher mean Pb-B concentration is found in smokers than in nonsmokers. It is clear from this investigation that in the general population, and even in Cd-exposed workers, Cd has no significant effect on ALA-D. Moreover, all the available evidence indicates that ALA-D activity of erythrocytes is a very sensitive and specific parameter of lead in blood.