Carlos Eduardo Rivas

Learn More
An on-line flow injection-hydride generation/atomic absorption spectrometry method was developed for the preconcentration and selective determination of inorganic arsenic [As(III) and As(V)] and its methylated species. The separation of the arsenic species was performed by an automated pH-selective arsines generation technique, using sodium(More)
The ability of dipyridamole (DIP) to scavenge oxygen metabolites generated by either activated human neutrophils (PMNs) or cell-free systems using luminol(s)- and lucigenin-enhanced chemiluminescence was investigated. In the presence of DIP (15-50 microM) a dose-dependent inhibition period was seen in phorbol myristate acetate (PMA)-stimulated PMNs as(More)
Coelomocytes comprise the immune system of earthworms and due to their sensitivity responding to a wide range of pollutants have been widely used as target cells in soil ecotoxicology. Recently, in vitro assays with primary cultures of coelomocytes based in the neutral red uptake (NRU) assay have been developed as promising tools for toxicity assessment(More)
The hepatic levels of glutathione in rats treated with buthionine sulfoximine (4 mmol/kg), an inhibitor of glutathione synthesis, were 72.5% +/- 4.9% of those determined in control animals. This decrease in glutathione concentration was prevented by the administration of glutathione monoethyl ester (7.5 mmol/kg). S-Adenosyl-L-methionine-synthetase activity(More)
Aceclofenac (Airtal) (1) is a photoallergic and phototoxic anti-inflammatory and analgesic agent. This drug is photolabile under aerobic and anaerobic conditions. Irradiation of an ethanol-solution of aceclofenac under oxygen or argon at 290-320 nm affords via decarboxlation compound 2 as the main isolated and spectroscopically identified photoproduct,(More)
The present study was undertaken to determine if the antipsychotic drug clozapine (CLZ) in the concentration range 2-50 microM can rescue polymorphonuclear cells (PMNs) from undergoing apoptosis. Our results indicate that 20 microM CLZ can rescue PMNs both from UVB-accelerated (28.0% vs. 45.9% for control without CLZ; P < 0.05) and from spontaneous (35.8%(More)
The phototoxic antitubercular drug pyrazinamide (1) is photolabile under irradiation with UV-A light as well as with a N2 laser (at 337 nm) in aerobic conditions. Irradiation in methanolic and in aqueous solutions of 1 produces four and three photoproducts, respectively. Their formation involves primary alpha-cleavage between the excited carbonyl of the(More)