Effect of Pb-exposure and B vitamin deficiencies on δ-aminolevulinic acid dehydratase activity among workers from Pb recycling plants.

Previous studies reported that Pb exposure causes a negative association with delta-aminolevulinic acid dehydratase activity (δ-ALAD), but the impact of Pb exposure (dose and time), B vitamin deficiencies, and lifestyle factors needs to be explored. In this study, the impact of Pb exposure, B vitamin deficiencies, and lifestyle factors on δ-ALAD activity among workers exposed to Pb from the Pb-recycling process was evaluated. Blood lead levels (BLLs), B vitamins (B6, B9, and B12), hematological factors (Hb% and HCT), lifestyle factors, and δ-ALAD activity was assessed in 170 male Pb-exposed workers engaged in the Pb recycling process. BLLs are estimated using the ICP-OES method. B vitamins in serum samples from workers were determined using the ELISA method. The δ-ALAD activity in whole blood samples was determined using the spectrophotometer method. The lifestyle factors were collected using a standard questionnaire. The δ-ALAD activity was significantly decreased in workers with the habits of alcohol use, tobacco consumption, hematocrit < 41%, mild and moderate categories of anemia, vitamin B6 and B12 deficiency, and BLL categories of 10-30, 30-50, and > 50 µg/dL. Multiple regression analysis revealed that the independent variables of alcohol consumption (ß = - 0.170; P = 0.025), BLLs (ß = - 0.589; P = 0.001) and Hb% (ß = 0.183; P = 0.001) significantly influenced the δ-ALAD activity with 44.2% (R2 = 0.442). Among the workers exposed to Pb from the Pb recycling plant, δ-ALAD activity was considerably reduced by Pb exposure, B vitamin deficiency, hematological parameters, and lifestyle factors.

Biochemical Diagnosis of Acute Hepatic Porphyria: Updated Expert Recommendations for Primary Care Physicians.

Acute hepatic porphyria (AHP) is a group of rare, metabolic diseases where patients can experience acute neurovisceral attacks, chronic symptoms, and long-term complications. Diagnostic biochemical testing is widely available and effective, but a substantial time from symptom onset to diagnosis often delays treatment and increases morbidity. A panel of laboratory scientists and clinical AHP specialists collaborated to produce recommendations on how to enhance biochemical diagnosis of AHP in the USA. AHP should be considered in the differential diagnosis of unexplained abdominal pain, the most common symptom, soon after excluding common causes. Measurement of porphobilinogen (PBG) and porphyrins in a random urine sample, with results normalized to creatinine, is recommended as an effective and cost-efficient initial test for AHP. Delta-aminolevulinic acid testing may be included but is not essential. The optimal time to collect a urine sample is during an attack. Substantial PBG elevation confirms an AHP diagnosis and allows for prompt treatment initiation. Additional testing can determine AHP subtype and identify at-risk family members. Increased awareness of AHP and correct diagnostic methods will reduce diagnostic delay and improve patient outcomes.

Nondestructive biomarkers in giant toad (Rhinella marina) to assess the effect of complex mixture of pollutants in Coatzacoalcos River, Mexico.

In this study, we evaluated the usefulness of nondestructive biomarkers approach in giant toads (Rhinella marina). We obtained blood samples and the residual condition index of toads from rural and industrial zones from Coatzacoalcos River, Mexico (COA). In the blood samples, we determined the activity of enzymes, lipid peroxidation, and the presence of cell death (apoptosis). We found that the activity of the enzyme delta-aminolevulinic dehydratase was lower. Still, the glutathione s-transferase activity and the percentage of apoptosis in erythrocytes were higher in the toads of COA than laboratory toads. Meanwhile, some biomarkers in toads showed differences when compared between Industrial and Rural zones. These results and correlations between biomarkers showed how the response changed in the toads living near the industrial zones. We demonstrate that a nondestructive biomarkers approach can be useful in environmental studies with anuran amphibians.

5-Aminolevulinate dehydratase porphyria: Update on hepatic 5-aminolevulinic acid synthase induction and long-term response to hemin.

BACKGROUND: 5-Aminolevulinic acid dehydratase (ALAD) porphyria (ADP) is an ultrarare autosomal recessive disease, with only eight documented cases, all of whom were males. Although classified as an acute hepatic porphyria (AHP), induction of the rate limiting hepatic enzyme 5-aminolevulinic acid synthase-1 (ALAS1) has not been demonstrated, and the marrow may also contribute excess 5-aminolevulinic acid (ALA). Two patients have died and reported follow up for the others is limited, so the natural history of this disease is poorly understood and treatment experience limited. METHODS: We report new molecular findings and update the clinical course and treatment of the sixth reported ADP patient, now 31 years old and the only known case in the Americas, and review published data regarding genotype-phenotype correlation and treatment. RESULTS: Circulating hepatic 5-aminolevulinic acid synthase-1 (ALAS1) mRNA was elevated in this case, as in other AHPs. Gain of function mutation of erythroid specific ALAS2 - an X-linked modifying gene in some other porphyrias - was not found. Seven reported ADP cases had compound heterozygous ALAD mutations resulting in very low residual ALAD activity and symptoms early in life or adolescence. One adult with a germline ALAD mutant allele developed ADP in association with a clonal myeloproliferative disorder, polycythemia vera. CONCLUSIONS: Elevation in circulating hepatic ALAS1 and response to treatment with hemin indicate that the liver is an important source of excess ALA in ADP, although the marrow may also contribute. Intravenous hemin was effective in most reported cases for treatment and prevention of acute attacks of neurological symptoms.

Use of Generalized Additive Model to Detect the Threshold of δ-Aminolevulinic Acid Dehydratase Activity Reduced by Lead Exposure.

BACKGROUND: Lead inhibits the enzymes in heme biosynthesis, mainly reducing δ-aminolevulinic acid dehydratase (ALAD) activity, which could be an available biomarker. The aim of this study was to detect the threshold of δ-aminolevulinic acid dehydratase activity reduced by lead exposure. METHODS: We collected data on 121 lead workers and 117 non-exposed workers when annual health examinations were performed. ALAD activity was determined by the standardized method of the European Community. ALAD G177C (rs1800435) genotyping was conducted using the polymerase chain reaction and restricted fragment length polymorphism (PCR-RFLP) method. In order to find a threshold effect, we used generalized additive models (GAMs) and scatter plots with smoothing curves, in addition to multiple regression methods. RESULTS: There were 229 ALAD1-1 homozygotes and 9 ALAD1-2 heterozygotes identified, and no ALAD2-2 homozygotes. Lead workers had significantly lower ALAD activity than non-exposed workers (41.6 ± 22.1 vs. 63.3 ± 14.0 U/L, p < 0.001). The results of multiple regressions showed that the blood lead level (BLL) was an important factor inversely associated with ALAD activity. The possible threshold of BLL affecting ALAD activity was around 5 µg/dL. CONCLUSIONS: ALAD activity was inhibited by blood lead at a possible threshold of 5 µg/dL, which suggests that ALAD activity could be used as an indicator for lead exposure regulation.

Blood lead level (BLL), δ-aminolevulinic acid dehydratase activity (ALAD), hemoglobin (Hb) and hematocrit (hct) in primary school-children and adult residents living in smelter rural areas in Kosovo.

The objective of this study was to investigate the effects of chronic environmental lead (Pb) exposure in blood lead level (BLL), δ-aminolevulinic acid dehydratase (ALAD) activity, hemoglobin (Hb) amount and hematocrit (Hct) value in primary schoolchildren and adults. Blood was obtained for BLL, ALAD, Hb and Hct measurements in 23 primary schoolchildren (girls and boys) and 117 adult residents (women and men) living in three villages (Kelmend, Boletin and Zhazhë) defined by concentric circles 2, 3 and 5 km in radius drawn around from the smelter-refinery complex "Trepça"in Zveçan and in Koliq village 40 km away. As expected, BLLs were substantially higher in the schoolchildren from smelter area compared with control (11 ± 4.2 µg/L and 6.9 ± 1.6 µg/L respectively) and in adult residents from Kelmend, Boletin and Zhazhë (24 ± 11.8, 12 ± 4.5, 11 ± 5.4 and 8.0 ± 2.8 µg/L respectively). Blood ALAD activity of children in Zhazhë is 16% inhibited compared to control and blood ALAD activity in adults in villages from smelter area is 32, 3%, 48, 4% and 17, 8% inhibited compared to control. There is no difference of Hb and Hct values in schoolchildren from Zhazhë and in adult residents from Kelmend and Zhazhë compared with control. Results of this study provide evidence of moderate inverse correlation between BLL and ALAD activity in both examined cohorts from smelter area. The inhibition of ALAD activity in primary schoolchildren and adults occurred at blood lead levels < 24 µg/L; consequently it can cause an increase of δ- Aminolevulinic acid.

Leukocyte apoptosis, TNF-α concentration and oxidative damage in lead-exposed workers.

Lead intoxication can generate pro-inflammatory conditions that have been proposed to be associated with cell injuries and oxidative stress. The pro-inflammatory state can participate in the pathophysiology of this toxicity to generate immune response dysfunctions, which could condition the presence of clinical manifestations and susceptibility to infections already described in lead-exposed patients. In the present work, we study workers of a battery recycler factory (n = 24) who are chronically exposed to lead and compared them with non-lead exposed workers (n = 17). Lead-exposed workers had high lead concentrations in blood (med 69.8 vs. 1.7 µg/dL), low δ-ALAD activity (med 149 vs. 1100 nmol PBG/h/mL), high lipid peroxidation (med 0.86 vs. 0.69 nmol/mL) and high erythrocytes apoptosis (med 0.81 vs. 0.50% PS externalization) in relation to non-lead exposed workers. Also, lead-exposed workers had a high incidence of signs and symptoms related to lead intoxication and a higher frequency of infections. The higher leukocyte apoptosis (med 18.3 vs. 8.2% PS externalization) and lower basal TNF-α concentration (med 0.38 vs. 0.94 pg/mL) in lead-exposed workers imply an immune response dysfunction; however, there was no difference in the TNF-α concentration when leukocytes were stimulated with lipopolysaccharide in whole blood (med 44 vs. 70 pg/mL), suggesting that lead-exposed workers might develop adaptation mechanisms to reduce basal TNF-α release through downregulation processes proposed for this cytokine.

Effects of combined administration of calcium, iron, zinc, chrysanthemum flavonoids, and DMSA on the treatment of lead intoxication in mice.

The effect of combined administration of calcium (Ca), iron (Fe), zinc (Zn), chrysanthemum flavonoids, and meso-2,3-dimercaptosuccinic acid (DMSA) on the treatment of lead (Pb) intoxication in mice was studied. One hundred ninety female mice (SPF level, aged 18-22 days) were randomly divided into two groups as experimental animals. Mice in group I (10 mice) served as normal control animals, and were administered deionized water containing 12.5 µL/L acetate acid for 6 weeks, whereas mice in group II (180 mice) were exposed to 0.1% (wt/vol) of lead acetate in deionized water for 6 weeks and served as experimental animals. After 6 weeks of successful modeling, 180 mice from group II (lead-exposed) were divided into 18 groups of 10 mice each, 16 of which were treated by the combined administration of Ca, Fe, Zn, chrysanthemum flavonoids, and DMSA by L16 (215 ) orthogonal design. The remaining two groups were given treatment with low and high doses of DMSA, respectively. After three weeks of intervention (ig), the optimal treatment group was identified according to its blood lead level, as well as some antioxidant indices in the blood, liver, and hippocampus. The results indicated that the combined administration of Fe, Zn, chrysanthemum flavonoids, and DMSA with low dosage had the most significant effect on increasing the activities of blood delta-aminolevulinic acid dehydratase and superoxide dismutase (SOD), hepatic SOD and hippocampus nitric oxide synthase while decreasing the blood lead level, the content of hepatic malondialdehyde and hippocampus nitric oxide; this was considered the optimal treatment group. There was no difference in the level of blood hemoglobin between the optimal treatment group and the model control group (the first group of the orthogonal experiment). The activities of blood glutathione (GSH), hepatic GSH and glutathione peroxidase of the optimal treatment group were the same as other groups', and the recovery of the related indexes in the optimal effect group closely resembled the high dosage DMSA group. It can be concluded that the coadministration of Fe, Zn, and chrysanthemum flavonoids along with a low-dose DMSA effectively reduces Pb poisoning and lead-induced oxidative damage in lead-exposed mice; the result may provide a theoretical reference for the treatment of Pb poisoning.

Influence of maternal labor time on delta-aminolevulinate dehydratase enzyme activity and markers of oxidative stress in newborns.

The purpose is to determine markers of oxidative stress related to the longer and shorter duration of labor (DOL) of pregnant women in the umbilical cord blood of neonates, not yet studied. Blood samples from the umbilical cord were collected from pregnant women with normal delivery and classified according to DOL in two groups: a group with DOL less than 310 min (n = 33) and a group with DOL greater than or equal to 310 min (n = 35). The oxidative stress parameters were analyzed by the quantification of thiobarbituric acid reactive substances (TBARS), nitrate/nitrite (NOx), protein thiol groups (P-SH) and non-protein (NP-SH), vitamin C and plasma iron reduction capacity (FRAP), in addition to the activity of the enzyme delta-aminolevulinate dehydratase (δ-ALA-D). The activity of the δ-ALA-D enzyme was shown to be decreased in longer DOL, however, the oxidant parameters and antioxidants were higher in the longer DOL, with the exception of NP-SH that was lower. The longer maternal DOL time is related to the alteration of δ-ALA-D enzyme activity and other parameters in neonates, suggesting an increase in the passage of maternal oxidative markers by umbilical cord blood.

Participation of phospholipase-A2 and sphingomyelinase in the molecular pathways to eryptosis induced by oxidative stress in lead-exposed workers.

The increment of eryptosis in lead-exposed workers has been associated with oxidative stress, having as the main mediator [Ca2+]i. However, other molecules could participate as signals, such as PLA2 and SMase, which have been proposed to increase PGE2 and ceramides, both involved in the increment of PS externalization due to osmotic stress. To study the role of these enzymes in lead intoxication, we studied 30 lead exposed workers and 27 non-lead exposed individuals. We found, compared to non-exposed subjects, lead intoxication characterized by high blood lead concentration (median = 39.1 µg/dL), and low δ-ALAD activity (median = 348 nmol of porphobilinogen/h/mL); oxidative stress with high lipid peroxidation (median = 1.31 nmol of malondialdehyde/mL) and low TAC (median = 370 mM Trolox equivalents); a higher enzymatic activity of PLA2 (median = 518 AFU/mg) and SMase (median = 706 AFU/mg) and higher eryptosis (median = 0.92% PS externalization). Correlation and conditional probability analyses permit to associate oxidative stress and eryptosis with high PLA2 activity. However, high SMase activity was only associated with PLA2 activity. The role of these enzymes in the signal path to eryptosis induced by oxidative stress in lead-exposed workers is discussed.

Longitudinal Study of Delta-Aminolevulinate Dehydratase Activity and Oxidative Profile in Healthy Pregnant Women.

Pregnancy is characterized by changes in various organs, triggering changes in the use of energy substrates and increased oxygen consumption. In addition, gestation is an oxidative event that can be assessed by the relationship between free radicals and antioxidants produced by the body. Excessive production of free radicals has detrimental effects such as damage to enzymes, carbohydrates, and DNA. Thus, the objective of this study was to evaluate the oxidative status and antioxidant responses throughout pregnancy through a longitudinal study. Reactive oxygen species were analyzed by means of thiobarbituric acid reactive substances and nitric oxide, the antioxidant system through vitamin C, sulfhydryl groups, total antioxidant capacity, and ferric reducing ability of plasma as well as enzymes such as catalase and delta-aminolevulinate-dehydratase in pregnant women in the three gestational trimesters (n = 30). According to the results, the markers of oxidative damage showed significant differences in the different gestational trimesters where they were increased in the second trimester when compared to the first trimester. The antioxidant defenses responded differently in each gestational trimester, suggesting a response pattern to try to combat the damage caused by free radicals, in order to stabilize the increase of oxidative stress caused in the second gestational trimester.

The effect of lead (Pb) exposure and iron (Fe) deficiency on intestinal lactobacilli, E. coli and yeast: A study in experimental rats.

OBJECTIVE: The current study investigated the additive effect of oral lead (Pb) exposure and dietary iron (Fe) deficiency on intestinal lactobacilli, E. coli, and yeast in SD rats. METHODS: Weanling rats were fed on control diet (CD) or iron deficient diet (ID) for 4 weeks, followed by oral Pb exposure for another 4 weeks. Lead exposure was withdrawn for 2 weeks, and then resumed after 2 weeks. Blood samples were collected to determine haemoglobin (Hb), serum iron, blood Pb and δ-Aminolevulenic acid dehydratase (ALAD) activity. Fecal samples were collected to enumerate the lactobacilli, E. coli and yeast population on selective agar media and determine Pb levels. RESULTS: Hb and serum Fe levels decreased significantly in iron deficient rats. Pb exposed rats had a significant increase in blood Pb levels and decreased ALAD activity. The lactobacilli population was significantly decreased (p<0.05) in ID rats compared to the CD group. Further, a significant decrease in the lactobacilli population was observed in Pb exposed rats irrespective of the dietary regimen. Upon withdrawal of Pb exposure, lactobacilli increased significantly in both the CD+Pb and ID+Pb groups, whereas re-exposure to Pb decreased lactobacilli population. The E. coli and yeast populations were inconsistent among both the ID and Pb exposed rats compared to controls. Fecal Pb levels increased significantly in Pb exposed rats irrespective of diet. CONCLUSION: An additive effect of dietary Fe deficiency and oral Pb exposure resulted in greater reductions in the intestinal lactobacilli population compared to either treatment alone. In addition, transient withdrawal of Pb exposure led to improved lactobacilli population irrespective of Fe status.

Combination therapy with vitamin C and DMSA for arsenic-fluoride co-exposure in rats.

INTRODUCTION: Arsenic and fluoride are recognized globally as the most serious inorganic contaminants in drinking water. As there is no safe and effective treatment for the cases of fluoride poisoning and combined arsenic-fluoride toxicity, the present study was planned to assess (i) the mechanism of combined exposure to arsenic and fluoride via biochemical and spectroscopic data; (ii) the effect of a thiol chelating agent, meso-2,3-dimercaptosuccinic acid (DMSA), either individually or in combination with the antioxidant vitamin C in reversing arsenic-fluoride toxicity; and (iii) whether combination therapy enhances arsenic and fluoride removal from blood and soft tissues. METHODS: Rats were exposed to arsenic (50 mg l-1) and fluoride (50 mg l-1) individually and in combination for 9 months and later administered DMSA (50 mg kg-1) via an i.p. route and vitamin C (25 mg kg-1) orally for 5 days. Biochemical parameters suggestive of alterations in the heme synthesis pathway, oxidative stress in blood, the liver and the kidneys, and concentrations of arsenic and fluoride in blood and soft tissues were studied. We also studied the infrared (IR) spectra of DNA extracted from the livers and kidneys of the normal and exposed animals. RESULTS: It was found that chronic arsenic and fluoride exposure led to an increased oxidative stress condition and impaired heme synthesis (67% inhibition in δ-aminolevulinic acid dehydratase activity and 38% increase in δ-aminolevulinic acid synthetase activity). The decreased antioxidant defense mechanism was marked by a 2.25 fold increased concentration of Reactive Oxygen Species (ROS) and a 28% decrease in the Glutathione (GSH) level. Interestingly, concomitant exposure to arsenic and fluoride did not lead to antagonistic effects as the toxic effects were the same as those seen during the individual exposure to both the toxicants. It suggests that toxicity depends on the dose and duration of exposure. Combination therapy with DMSA and vitamin C showed a better efficacy than monotherapy in terms of reducing the arsenic and fluoride burden (more than 70% in blood and soft tissues) as well as reversal in the altered biochemical variables indicative of oxidative stress and tissue damage (80-85%). The infrared (IR) spectra of DNA isolated from the liver and kidneys suggested that the treatment with vitamin C and DMSA had no beneficial effects in terms of reversing DNA damage. CONCLUSION: On the basis of the above observations, we suggest that the combinational therapy of DMSA and vitamin C would be more effective in arsenic and/or fluoride toxicity; however, more detailed studies are required to address recoveries in DNA damage.

Effect of sub-chronic exposure to lead (Pb) and Bacillus subtilis on Carassius auratus gibelio: Bioaccumulation, antioxidant responses and immune responses.

Lead (Pb) poisoning in humans and fish represents a significant global problem. Bacillus subtilis (B. subtilis) is a widely used probiotic in aquaculture. Carassius auratus gibelio (C. gibelio) is one of the most important aquaculture species with great commercial value. The objective of this study was to evaluate the potential of B. subtilis in ameliorating lead-induced toxicity in C. gibelio. The fish were exposed for 60 days to waterborne Pb at 0, 0.05, 0.5 and 1 mg/L and/or dietary B. subtilis at 109 cfu/g. After 30 and 60 days, the fish were sampled and bioaccumulation, antioxidant activity and immune responses were assessed. The results revealed that B. subtilis confers significant protective effects against lead toxicity by preventing alterations in the levels of bioaccumulation, superoxide dismutase, catalase and glutathione. B. subtilis also assists in the recovery of blood δ-aminolevulinic acid dehydratase, lysozyme, and IgM levels while regulating the expression of immune-related genes including IL-10, lysozyme, TNF-α, IgM and Hsp70 after 60 days of lead exposure. Our results suggest that administration of B. subtilis (109 cfu/g) has the potential to combat lead toxicity in C. gibelio.

House sparrow biomarkers as lead pollution bioindicators. Evaluation of dose and exposition length on hematological and oxidative stress parameters.

House sparrows (Passer domesticus) have been proposed as a key ecological indicator of urban pollution. Remarkably, we lack knowledge about the physiological effects of lead on this bird species. Therefore, this study was aimed to evaluate the effect of Pb on several physiological parameters in house sparrows exposed to environmental Pb concentrations. In a first experiment, birds were exposed to Pb sub-lethal doses (from 1.3 to 14.0 µg of Pb/g animal/day) during 5 days, which resulted in a dose response increase of blood Pb levels and decrease of blood ALAD activity. However, at the higher doses tested (> 7 µg of Pb/g animal/day) the blood ALAD activity inhibition (~82%) remained constant. Hematocrit and hemoglobin were significantly reduced only at the highest-doses, and the stress indicator, heterophils to lymphocyte (H/L) ratio, did not show apparent changes. In a second experiment, house sparrows were exposed to Pb in drinking water (12.3 ppm) during either 15 or 30 days. Pb concentration used in this study was enough to produce blood lead levels equivalents to those found recently in house sparrows inhabiting urban areas, reduced blood ALAD activity and inversion of the H/L ratio. Decreasing blood ALAD activities were correlated with increasing blood Pb levels. In addition, Pb exposure produced modification in the levels of hepatic antioxidant enzymes, increased GST activity and decreased CAT activity, without lipid peroxidation. In conclusion, our results suggest that blood ALAD activity is a reliable and sensitive biomarker for environmental Pb exposure in house sparrows, additionally chronic exposure produce physiological stress (H/L inversion) and small changes in antioxidant enzyme activity. Finally, this specie could be considered a bioindicator for monitoring the urban Pb contamination.

Influence of gestational diabetes on the activity of δ-aminolevulinate dehydratase and oxidative stress biomarkers.

OBJECTIVES: This study aimed to evaluate the activity of delta-aminolevulinate dehydratase (δ-ALA-D) and oxidative stress biomarkers in pregnant women with gestational diabetes mellitus (GDM), in order to demonstrate the involvement of oxidative stress in this condition, which presents pathophysiology still undetermined. METHODS: δ-ALA-D activity, lipid peroxidation estimated as the levels of thiobarbituric acid reactive substances (TBARS), protein (P-SH) and non-protein thiol (NP-SH) content, catalase (CAT) activity and concentration of vitamin C (VIT C) in samples of pregnant women with GDM (n = 48) and in healthy pregnant women (n = 30), who constituted the control group. RESULTS: The δ-ALA-D activity was significantly lower in pregnant women with GDM compared to controls, as well as levels of thiols, VIT C and CAT activity. Lipid peroxidation was higher in GDM group. DISCUSSION: The results suggest that the main factor for the increase in oxidative stress and reduced δ-ALA-D activity in diabetic pregnant women is gestational hyperglycemic environment, which changed the redox balance and interfered on mechanism of the δ-ALA-D activity in relation to normoglycemic pregnant women.

Effects of Zinc and N-Acetylcysteine in Damage Caused by Lead Exposure in Young Rats.

This study investigated the toxicity of rats exposed to lead acetate (AcPb) during the second phase of brain development (8-12 days postnatal) in hematological and cerebral parameters. Moreover, the preventive effect of zinc chloride (ZnCl2) and N-acetylcysteine (NAC) was investigated. Pups were injected subcutaneously with saline (0.9% NaCl solution), ZnCl2 (27 mg/kg/day), NAC (5 mg/kg/day) or ZnCl2 plus NAC for 5 days (3rd-7th postnatal days), and with saline (0.9% NaCl solution) or AcPb (7 mg/kg/day) in the five subsequent days (8th-12th postnatal days). Animals were sacrificed 21 days after the last AcPb exposure. Pups exposed to AcPb presented inhibition of blood porphobilinogen-synthase (PBG-synthase) activity without changes in hemoglobin content. ZnCl2 pre-exposure partially prevented PBG-synthase inhibition. Regarding neurotoxicity biomarkers, animals exposed to AcPb presented a decrease in cerebrum acetylcholinesterase (AChE) activity and an increase in Pb accumulation in blood and cerebrum. These changes were prevented by pre-treatment with ZnCl2, NAC, and ZnCl2 plus NAC. AcPb exposure caused no alteration in behavioral tasks. In short, results show that AcPb inhibited the activity of two important enzymatic biomarkers up to 21 days after the end of the exposure. Moreover, ZnCl2 and NAC prevented the alterations induced by AcPb.

Association between Blood Lead Levels and Delta-Aminolevulinic Acid Dehydratase in Pregnant Women.

Blood lead levels (BLLs) and delta-aminolevulinic acid dehydratase (ALAD) activity are considered biomarkers of lead exposure and lead toxicity, respectively. The present study was designed to investigate the association between BLLs and ALAD activity in pregnant women from Durango, Mexico. A total of 633 pregnant women aged 13-43 years participated in this study. Blood lead was measured by a graphite furnace atomic absorption spectrometer. ALAD activity was measured spectrophotometrically. Mean blood lead was 2.09 ± 2.34 µg/dL; and 26 women (4.1%) crossed the Centers for Disease Control (CDC) recommended level of 5 µg/dL. ALAD activity was significantly lower in women with levels of lead ≥5 µg/dL compared to those with BLLs < 5 µg/dL (p = 0.002). To reduce the influence of extreme values on the statistical analysis, BLLs were analyzed by quartiles. A significant negative correlation between blood lead and ALAD activity was observed in the fourth quartile of BLLs (r = -0.113; p < 0.01). Among women with blood lead concentrations ≥2.2 µg/dL ALAD activity was negatively correlated with BLLs (r = -0.413; p < 0.01). Multiple linear regression demonstrated that inhibition of ALAD in pregnant women may occur at levels of lead in blood above 2.2 µg/dL.

Delta-aminolevulinate dehydratase activity and oxidative stress markers in preeclampsia.

Preeclampsia is an important pregnancy-specific multisystem disorder characterized by the onset of hypertension and proteinuria. It is of unknown etiology and involves serious risks for the pregnant women and fetus. One of the main factors involved in the pathophysiology of preeclampsia is oxidative stress, where excess free radicals produce harmful effects, including damage to macromolecules such as lipids, proteins and DNA. In addition, the sulfhydryl delta-aminolevulinate dehydratase enzyme (δ-ALA-D) that is part of the heme biosynthetic pathway in pro-oxidant conditions can be inhibited, which may result in the accumulation of 5-aminolevulinic acid (ALA), associated with the overproduction of free radicals, suggesting it to be an indirect marker of oxidative stress. As hypertensive pregnancy complications are a major cause of morbidity and mortality maternal and fetal where oxidative stress appears to be an important factor involved in preeclampsia, the aim of this study was to evaluate the activity of δ-ALA-D and classic oxidative stress markers in the blood of pregnant women with mild and severe preeclampsia. The analysis and quantification of the following oxidative stress markers were performed: thiobarbituric acid-reactive species (TBARS); presence of protein and non-protein thiol group; quantification of vitamin C; Catalase and δ-ALA--D activities in samples of blood of pregnant women with mild preeclampsia (n=25), with severe preeclampsia (n=30) and in a control group of healthy pregnant women (n=30). TBARS was significantly higher in women with preeclampsia, while the presence of thiol groups, levels of vitamin C, catalase and δ-ALA-D activity were significantly lower in groups of pregnant women with preeclampsia compared with healthy women. In addition, the results showed no significant difference between groups of pregnant women with mild and severe preeclampsia. The data suggest a state of increased oxidative stress in pregnant women with preeclampsia compared to healthy pregnant women, which may be related to the complications of this disease.

Effects of sub-lethal and chronic lead concentrations on blood and liver ALA-D activity and hematological parameters in Nile tilapia.

Liver and blood δ-aminolevulinic acid dehydratase (ALA-D) inhibition by exposure to sub-lethal lead concentrations over time in Nile tilapia (Oreochromis niloticus) were investigated. All three lead concentrations (1mgkg(-1), 10mgkg(-1) and 100mgkg(-1)) significantly inhibited ALA-D activity in blood (319±29.2; 180±14.6 and 172±19µmols(-1)h(-1)L(-1) respectively) and liver (302±5.84; 201±41.4 and 93±22.1µmols(-1)h(-1)L(-1)) 24h after injection relative to controls (blood: 597±37.0µmols(-1)h(-1)L(-1); liver: 376±23.1µmols(-1)h(-1)L(-1)). Blood ALA-D was greatly inhibited in all but the highest lead dose. Fish were then exposed to 1mgkg(-1) lead for 9 days, and presented short-term hyperglycemia, decreased hemoglobin and hematocrit values and time-dependent blood ALA-D activity inhibition, corroborating blood ALA-D activity as being more suitable for investigating lead effects, showing dose and time-dependent ALA-D inhibition after lead exposure. The results of the present study also demonstrated that fish size affects blood ALA-D activity, as fish from the 24-h assay, which were slightly smaller (approximately 200g), showed higher ALA-D inhibition in response to lead exposure when compared to the fish from the 9-day assay (approximately 500g). Thus, fish size should always be taken into account both in the field and in laboratory settings, and efforts should be made to obtain uniform fish size samples for biomarker studies.