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J L Vieira

Publications and source records attributed to J L Vieira.

11 recordsLinked to original sources
PubMed2001

Drug monitoring of quinine in men with nonsevere falciparum malaria: study in the Amazon region of Brazil.

Quinine sulfate has been the drug of choice for the treatment of the ever-increasing number of cases of falciparum malaria in tropical countries. Because of the spectrum of adverse effects produced by the drug in the so-called cinchona syndrome, the variation in its pharmacokinetics during the episodes of falciparum malaria, and the different therapeutic regimens proposed in different countries, the authors monitored quinine plasma concentrations in daily samples of 20 men of the Amazon region in Brazil with nonsevere falciparum malaria who were administered 1 g quinine sulfate every 12 hours for 7 days. Three blood samples were collected from each patient each day: two immediately before administration of the drug (7 am and 7 pm) and one at 11 am. A total of 440 samples were analyzed by a validated method developed in the authors' laboratories using the high-performance liquid chromatographic technique. The overall quinine plasma levels obtained varied from 1.52 to 16.89 microg/mL. From the second day of treatment, overall levels varied from 2.33 to 14.29 microg/mL; the peak concentrations showed values from 4.22 to 16.89 microg/mL, showing the efficacy of the therapeutic regimen used. Adverse effects (signs and symptoms of cinchonism) were observed in all patients. However, no cases of hypoglycemia were detected. Intrapatient comparisons of the obtained quinine plasma concentrations were statistically significant. The quinine dose may be reduced on day 4 of treatment when asexual parasitemia is absent. This way, no resistance to the drug is observed, cinchonism can be minimized, and good adherence to the regimen is obtained.

Adult↗
PubMed1996

[Determination of total mercury in water samples, sediments and solids in suspension in aquatic systems by cold-vapor atomic absorption spectrophotometry].

The use of metallic mercury in the extraction and concentration of gold causes the discarding of tons of this metal in the environment, leading to a considerable increase in the natural levels of the same and the contamination of the surrounding areas. Thus it is extremely important to monitor the presence of this metal in various sectors of the environment with a view aiming to preventing human exposure to excessive concentrations which can result in serious episodes of mercury poisoning. It is also important to estimate the possibility of river sediments becoming potential sources of contamination of human beings. The determination of total mercury was undertaken by using cold vapor atomic absorption spectrometry. River waters, as well as sediments and suspended solids were used as samples for the standardization of the analytical procedure. Later on, this method was tested on samples originating in gold mining areas for the purpose of assessing its validity.

Environmental Monitoring↗
PubMedDate not supplied

[Total mercury in hair samples of inhabitants of Tapajós River, Pará State, Brazil].

This study evaluates human exposure to methylmercury in fishermen and their families in four villages on the Tapajós river: Rainha, Barreiras, São Luís do Tapajós and Paraná-Mirim. Hair analyses were performed with atomic absorption spectophotometry. Total hair mercury levels varied between 2.9mg/g and 71.5mg/g. Paraná-Mirim showed the lowest level. The highest level was found in São Luís do Tapajós and Barreiras. The hair mercury was six to seven times higher than the established safe limit of 10mg/g. No statistically significant difference was found between the mean level of total mercury taken from the inhabitants living downstream and upstream in Itaituba village (p > 0.05). These results confirm that human exposure to methylmercury is occurring on the Tapajós river and suggest that continued fish ingestion in that region is a potential risk factor for the appearance of symptoms and signs of Minamata disease. An immediate epidemiological survey program is recommended.

Animals↗
PubMedDate not supplied

[Methylmercury human exposure in riverside villages of Tapajos basin, Pará State, Brazil].

Evaluation of total human exposure to mercury and methylmercury was effected in riverine villages along the Tapajos river and in the metropolitan area of Belem city, state of Para, Brazil, by using total mercury and methylmercury concentrations in hair samples in 1994 and 1995. It was observed that average concentrations of total mercury are in a range from 2 +/- 1 microg/g-1 to 20.5 +/- 12. 1 microg/g-1. While methylmercury average concentration varies from 1. 4 +/- 0.7 microg/g-1 to 18.5 +/- 11 microg/g-1. These results confirm mercury contamination in the Tapajos river and possible appearance of mercury intoxication symptoms, and recommends the monitoring of compounds in hair samples as well as the need for epidemiological and clinical studies for human health prevention and control of mercury intoxication.

Adult↗