Biomedical subjects

J Mejía

Publications and source records attributed to J Mejía.

3 recordsLinked to original sources

PubMed1999

[A method for assessing health risks in mining sites].

OBJECTIVE: Considering the health risk associated with mining areas, in this work a methodology for the health assessment of this kind of hazardous sites is proposed. MATERIAL AND METHODS: The methodology includes a toxicological assessment, an environmental monitoring of metals, and the exposure assessment of the high risk population. The scheme was evaluated in the mining area of Villa de la Paz, San Luis Potosi, Mexico. The toxicological studies were done in rats treated with mining waste, biomarkers of effect for liver and central nervous tissue were analyzed. Metals levels in surface soil, household dust and water were studied. Finally, urinary arsenic was quantified in children. RESULTS: Neurotoxicity and hepatotoxicity of the mining waste were shown in rats. Then, arsenic and lead levels were analyzed in surface soil, household dust, and water. In all three media, exposure points, heavily contaminated with both metals, were localized. Finally, high levels of urinary arsenic were found in children living in the vicinity of the mine. CONCLUSIONS: Taking into account all these results, the Mexican authorities concluded that a high health risk is present in Villa de la Paz, and a remediation program is in progress.

Animals↗

PubMed1995

Arsenic increased lipid peroxidation in rat tissues by a mechanism independent of glutathione levels.

The role of lipid peroxidation in the mechanism of arsenic toxicity was investigated in female rats pretreated with N-acetylcysteine (NAC, a glutathione [GSH] inducer) or with buthionine sulfoximine (BSO, a GSH depletor). Rats were challenged with sodium arsenite, and sacrificed 1 hr after this treatment. Results showed that arsenic decreased GSH levels and increased lipid peroxidation in liver, kidney, and heart, with a larger effect at 18.2 mg/kg than at 14.8 mg/kg for lipid peroxidation induction. In the liver of rats treated with arsenic, pretreatment with NAC increased the levels of GSH and decreased lipid peroxidation. In kidney and heart, NAC pretreatment protected the tissues against arsenic-induced depletion of GSH levels, but the same degree of protection was not found for lipid peroxidation induction. In its turn, BSO had an additive effect with arsenic in lowering the levels of GSH in the liver and kidney, but an inverse correlation between GSH levels and lipid peroxidation was found only in liver. Arsenic content in tissues of rats pretreated with NAC was lower than in rats treated only with arsenic. In rats with depleted levels of GSH (BSO-pretreated rats), a shift in arsenic tissue distribution was found, with higher levels in skin and lower levels in kidney. A clear tendency for a positive correlation between arsenic concentration and lipid peroxidation levels was found in liver, kidney, and heart.

Acetylcysteine↗

PubMed1975

The prevalence of hepatitis B antigen among hepatitis patients and residents of Peru.

Single radial immune diffusion and counterelectrophoresis tests were used to examine 2,593 serum speciments from apparently healthy men, women, and children of Peru for the presence of hepatitis B antigen (Australia antigen). The object was to estimate the prevalence of the antigen in two contrasting geographic regions and to investigate the relationship between presence of the antigen and jungle hepatitis in eastern Peru. In connection with the latter goal, both single and serial serum samples collected from hepatitis cases during an epidemic in the northeast were also examined. Of the 2,593 apparently healthy subjects, the tests showed 1.4 per cent were carrying the antigen. However, when the data were broken down by geographic region it was found that 1.8 per cent of the subjects from eastern Peru were carriers, as compared to only 0.5 per cent of those from the northern coast. Moreover, incidences as high as 5 and 6.4 per cent were found in selected eastern areas, and a peak figure of 14.3 per cent was found in sera from children living in some of these areas. Comparison of the proportions of male and female sera positive for the antigen indicated that the proportion of males with HB Ag was nearly twice as high. However, sera collected from Indians of 20 different eastern tribes and from mestizos in the eastern region showed roughly the same proportion of samples positive for HB Ag in each ethnic group. The study also showed a close correlation between presence of the antigen and hepatitis infection during a 1972-1973 epidemic in eastern Peru. Testing of sera taken from hepatitis patients at that time showed many patients to be carrying HB Ag, specially in cases where serial blood samples were available. In all, positive test results were obtained for 81.2 per cent of the patients from whom two or more samples had been obtained.

Adolescent↗