Lead toxicity and chelation therapy

Influence of lead acetate on glutathione and its related enzymes in different regions of rat brain

This study is intended to determine the effect of lead acetate on glutathione and its associated enzymes of rat brain. Wistar male rats were treated with lead acetate (500 ppm) through drinking water for a period of 8 weeks and parallel controls were maintained. They were sacrificed at the first, fourth and eighth week to isolate whole brains, which were separated into cerebellum, hippocampus, frontal cortex and brain stem. The data indicate enhanced (P < 0.05) glutathione peroxidase (G-Px) activity at most of the intervals for cerebellum, frontal cortex and brain stem, suggesting conversion of GSH to GSSG, while the hippocampus showed decreased levels. In contrast, glutathione reductase (GR) decreased significantly (P < 0.05) in cerebellum, frontal cortex and brain stem at all intervals except the fourth week in frontal cortex and brain stem. Hippocampus exhibited a gradual and significant (P < 0.05) increase in GR activity. Glutathione-S-transferase (GSTase) activity increased with exposure time in all four brain tissues, showing protection against lead acetate toxicity. The GSH and GSSG levels correlated well with the activities of GPx, GR and GSTase in all four regions of the brain. Overall the results indicate that lead acetate affects glutathione-related enzymes differentially and these changes can be attributed to differences in tissue susceptibility.

Pyrithione and 8-hydroxyquinolines transport lead across erythrocyte membranes

Acute and chronic lead poisoning remains a significant health problem. Although chelating agents can bind to plasma lead, they cannot cross cell membranes where the total body lead burden resides, and are thus inefficient at reducing the total body lead burden. Recently, calcium and sodium ionophores have been shown to transport lead across cell membranes providing a novel method for reducing total body lead stores. We recently found that clioquinol, an 8-hydroxyquinoline derivative, can act as a zinc ionophore. We postulated that zinc ionophores might also be able to transport lead across biological membranes. To study this, we loaded lead in vitro into human erythrocytes and then studied the ability of zinc ionophores to transport lead into the extracellular space, where it was trapped with a lead chelator. Using inductively coupled plasma mass spectrometry (ICP-MS), we found that several 8-hydroxyquinoline derivatives, as well as the zinc and sodium salts of pyrithione (N-hydroxypyridine-2-thione), reduced erythrocyte lead content. The water-soluble compound, sodium pyrithione, was able to reduce lead in citrated whole blood, without partitioning into the erythrocytes. These results indicate that two classes of zinc ionophores can transport lead across a biological membrane, and they confirm that these ionophores are not cation-specific. Lead ionophores may prove useful in mobilizing lead into the extracellular space, thereby improving the efficacy of chelation therapy, in vivo or ex vivo.

Lead poisoning due to adulterated marijuana in leipzig

BACKGROUND

Between August and December 2007, a mass poisoning due to adulterated marijuana was uncovered in the area of Leipzig, Germany.

METHODS

Retrospective reports of patients with lead poisoning who were treated at Leipzig University Hospital. Analysis of data from the local health office, where marijuana consumers could have their blood lead concentration determined.

RESULTS

At Leipzig University Hospital, 35 patients (7 female; age 24.2 +/- 4.4 years) had to be treated for lead poisoning (blood lead levels 1063.3 +/- 864.0 microg/L). Five hundred ninety-seven marijuana consumers (439 men, 158 women; age 26.9 +/- 4.8 years) had their blood lead levels measured at the local health office. Among them, 27.3% had lead levels above the HBM-II threshold, 12.2% had concentrations that required monitoring, and 60.5% had levels below the HBM-I threshold.

CONCLUSION

Drug consumption should be considered in otherwise unexplained anemia and abdominal colic. Several hundred people suffered lead poisoning presumably resulting from the desire of drug dealers to maximize profits.