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Biomedical subjects

J C Moreira

Publications and source records attributed to J C Moreira.

At least 19 recordsLinked to original sources
PubMed2002

Atmospheric BTX and polyaromatic hydrocarbons in Rio de Janeiro, Brazil.

Polycyclic aromatic and monoaromatic (benzene, toluene and xylene, or BTX) hydrocarbons were monitored in Rio de Janeiro, Brazil, during the summer of 1998/1999. The levels of these aromatic chemicals decreased with distance from main roads, indicating mobile sources are the main pollutant emitters in this Latin American city. Benzo[ghi]perylene/indeno[1,2,3-cd]pyrene and benzene/toluene ratios corroborate this idea. However, higher benzene/toluene ratios at one of the major access routes into the city suggest pollutant inputs from a nearby refinery. Literature data were reviewed in order to outline differences and similarities among sources and levels of aromatic pollutants in large urban agglomerations worldwide. Concentrations of benzo[a]pyrene and benzene, which are well-known carcinogenic chemicals, were relatively low in Rio de Janeiro. This fact was attributed to specific atmospheric conditions during the tropical summer and differences in vehicle fuel composition.

Air Pollutants↗
PubMed2002

The effects of constant and alternating temperatures on the reproductive potential, life span, and life expectancy of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae).

Ovarian development, oviposition, larval eclosion, ornithine decarboxylase (ODC) activity, ovarian, testis and ejaculatory apodeme measurements (length, width, and area), and the number of spermatozoa of Anastrepha fraterculus (Wiedemann) were analyzed at alternating (20 degrees/6 degrees C and 20 degrees/13 degrees C) and constant (6 degrees C; 25 degrees C) temperatures. Life span and life expectancy were also analyzed for both genders. All the results suggest that temperature, especially alternating temperatures, increase not only male and female reproductive potential but also their life span and life expectancy. These changes can be a powerful strategy triggered by A. fraterculus as a means to survive the stressful temperature conditions found in winter in the apple production region in Brazil, enabling this species to increase its population density and cause apple damage when spring begins.

Animals↗
PubMed2001

Neonatal iron exposure induces oxidative stress in adult Wistar rat.

Oxidative stress and excess of iron in the brain has been implicated in a variety of acute and chronic neurological conditions. The neonatal period is critical for the establishment of normal iron content in the adult brain. In the present study, the long-term oxidative effects of iron exposure during this period were assessed by treating Wistar rats orally with 0, 7.5 or 15 mg Fe(+2)/kg of body weight on postnatal days 10-12. Thiobarbituric acid reactive species, protein carbonyl, superoxide dismutase activity were measured at the age of 3 months. It was found that there was an increase in thiobarbituric acid reactive species and protein carbonyl in the substantia nigra of iron treated rats. In contrast, oxidative stress in the striatum was decreased. Superoxide dismutase activity was decreased in the substantia nigra iron treated rats. There were no differences in cerebellum measures among the groups. Our results demonstrated that iron supplementation in a critical neonatal period induced oxidative stress and modulated SOD activity in the adult life in selective brain regions.

Age Factors↗
PubMed2001

Chemical safety and governance in Brazil.

Chemical safety is recognized in Agenda 21(UNCED--Rio 92), as one of the most serious problems to be faced worldwide being a problem not just of governability, restricted more to the role of states and governments, but of governance at the national and international levels. It poses greater challenges for countries like Brazil where the issues of democracy, security, sustainability and equity, which are fundamental to governance, are merely incipient and still far from solved. Taking as references the analysis of four cases in the Brazilian context, we illustrate the situation from less densely populated areas (as in the cases of mercury use by gold miners in the Amazon and pesticides in agricultural producing areas), through medium-sized towns (as in the accident with cesium 137 in Goiânia), to the major urban and industrial centers (as in the cases of lead from battery renovators and benzene in the oil and steel industries and oil refineries). What can be seen is a situation where problems connected with chemical safety have grown in intensity and extent far more than the capacity to deal with them. In industrializing countries, the formulation of chemical safety policies must take into account not only the complexity and uncertainties involved in understanding the problems, but also the aspects relating to the different modes and levels of vulnerability. This is necessary in order to attempt to build better contextualized and more participatory knowledge and decision-making processes at the local and global levels, which we take as basic prerequisites for governance.

Brazil↗
PubMed2001

Electrochemical determination of trace amounts of environmentally important dyes.

A number of dyes exhibit genotoxic or ecotoxic properties leading to the need for sensitive and selective methods for their determination. Because of the easy reducibility of dyes, modern polarographic and voltammetric methods (differential pulse polarography on classical dropping mercury electrode, differential pulse voltammetry on hanging mercury drop electrode or adsorptive stripping voltammetry) are suitable for the determination of trace amounts of these substances in the general environment in the vicinity of production plants. The scope and limitations of these methods is reviewed and optimum conditions for recently developed methods are summarized. It is shown that the sensitivity of newly developed polarographic and voltammetric methods is sufficient even for the most demanding applications and their selectivity can be increased by their combination with preliminary separation using thin layer chromatography or liquid extraction.

Coloring Agents↗
PubMed2001

Retinol supplementation induces oxidative stress and modulates antioxidant enzyme activities in rat sertoli cells.

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular oxidative stress and modulated superoxide dismutase, catalase and glutathione peroxidase activities. Retinol (7 microM) significantly increased TBARS, conjugated dienes, and hydroperoxide-initiated chemiluminescence in cultured Sertoli cells. In response to retinol treatment superoxide dismutase, catalase and glutathione peroxidase activities increased. TBARS content and catalase activities were decreased by a free radical scavenger. These findings suggest that retinol may induce oxidative stress and modulate antioxidant enzyme activities in Sertoli cells.

Animals↗
PubMed2001

Mitogenic signaling mediated by oxidants in retinol treated Sertoli cells.

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol-induced oxidative stress is accompanied by cellular proliferation. Retinol (7 microM) significantly induced thiobarbituric acid reactive species (TBARS) formation, which was inhibited by trolox, superoxide dismutase, N-acetylcysteine and ethanol. This was accompanied by an increase in DNA synthesis and focus formation in cultured rat Sertoli cells. Antioxidants and ethanol inhibited retinol-induced DNA synthesis. Our findings suggest that retinol-induced oxidative stress was associated with cellular proliferation complementing our understanding of the significance of retinol supplementation in neoplastic transformation.

Animals↗
PubMed2001

[Influence of socioeconomic factors on the pesticides poisoning, Brazil].

OBJECTIVE: The indiscriminate use of pesticides has been contributing for the environmental quality degradation, as well as it increases the occupational exposures to these products, determining a serious public health problem in rural areas. The purpose of this study was to evaluate the exposures of rural workers of Rio de Janeiro State to anticholinesterasic pesticides, through the analyses of the acetylcholinesterase from red cells (AChE) and plasmatic butyrilcholinesterase (BChE) levels. Social-economic factors, such as the educational level of these workers, can strongly influence this situation, reason why the impact of some social-economic indicators and practices of pesticides' use in the human contamination status for rural areas were also evaluated. METHODS: The evaluation of rural workers exposure to pesticides was performed to a random sample of 55 workers among the 300 inhabitants of the study area - five communities of Magé county, RJ. The AChE and BChE activities were determined to these workers. The enzymatic activities were evaluated according to the Ellman's method modified by Oliveira-Silva. Social-economic and pesticides use data were collected by a structured interview. The possible role of social-economic and pesticide use indicators as determinants of the worker's contamination was estimated by multivariate statistic techniques, using the enzymatic activity as the dependent variable and the social-economics pesticides use indicators as independent variables. RESULTS AND CONCLUSIONS: The data showed distinct results concerning the incidence of excessive exposure, according to the enzymatic indicator used. In the studied sample, a result of 3.0 % was found for the BChE values, and 41.8 %, according to AChE. Individuals with at least one positive enzymatic indicator result were considered as "intoxicated". When these data were compared to the social-economic and pesticides use factors, it was showed the importance of educational level in the prevalence of intoxication. The others indicators studied did not showed any significant and evident correlation.

Acetylcholinesterase↗
PubMed2001

[Communication related to pesticides use in a rural area of the state of Rio de Janeiro, Brazil].

OBJECTIVE: To assess communications aspects related to pesticide use in a rural area of the Rio de Janeiro state, Brazil. METHODS: The study was carried out in the area of São Lourenço stream. It was based on methodological triangulation comprising: semi-structured interviews and observation of a local population sample (about 600 inhabitants); structured questionnaire to collect data on the local community; and records of lectures given by argonomic engineers, pesticides traders and other public service professionals. RESULTS AND DISCUSSION: This study pointed out to the historical misinformation on pesticides in rural areas; the emphasis on technical language in educational and training activities available which constitutes a barrier for rural workers knowledge acquisition and empowerment; and the industry/commerce's pressure to legitimate pesticide trading, reinforcing the existing communication process, resulting in unfavorable inclusion of the rural worker into a broader market economy.

Brazil↗
PubMed2001

Intercellular contact-dependent survival of human A549, NCI-H596 and NCI-H520 non-small cell lung carcinoma cell lines.

In the present study, we examined the relationship between cell phenotype and cell survival of three human non-small cell lung carcinoma cell lines (A549, NCI-H596 and NCI-H520). Cells in exponential growth at various densities were incubated for 24 h at 37 degrees C in a 5% CO2 humidified atmosphere and then exposed to UV radiation for 1 min (256 nm, 40 W, source-to-target distance 100 cm). After two days the surviving cells were quantified by sulforhodamine beta staining and DNA fragmentation assay. The differences in UV sensitivity at 60 x 10(3) cells/cm2 among the cell lines were not related to the proliferative state of the cells but to the extent of intercellular contact. In contrast to A549 and NCI-H596, irradiated NCI-H520 cells presented lower DNA fragmentation and an aggregated cell culture phenotype even prior to confluence, suggesting that a contact-effect mechanism provides further protection against UV radiation.

Carcinoma, Non-Small-Cell Lung↗
PubMed2000

Lipid peroxidation in hippocampus early and late after status epilepticus induced by pilocarpine or kainic acid in Wistar rats.

Oxidative stress has been implicated in a variety of acute and chronic neurologic conditions, including epilepsy. Both the kainic acid and pilocarpine are useful models of temporal lobe epilepsy in rodents. As an index of lipid peroxidation the level thiobarbituric acid reactive substances (TBARS) was measured after the status epileticus induced by pilocarpine or kainic acid. In hippocampus there was a slight enhancement in the TBARS levels measured 12-14 h after the end of status epileticus induced by pilocarpine and kainic acid. The TBARS levels in pilocarpine treated animals was significantly decreased late after status epileticus and in kainic acid model the TBARS returned to basal levels. These results indicating a putative role of reactive oxygen species in kainic acid and pilocarpine induced epilepsy.

Animals↗
PubMed2000

Retinol-induced elevation of ornithine decarboxylase activity in cultured rat Sertoli cells is attenuated by free radical scavenger and by iron chelator.

We investigated retinol effects in ornithine decarboxylase activity in Sertoli cells. We also tested the hypothesis that free radical scavengers and iron chelators may attenuate the effect of retinol. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with retinol by 24 h with or without mannitol (1 mM) or 1,10 phenanthroline (100 microM). We measured ornithine decarboxylase and catalase activities and malondialdehyde concentrations in response to retinol treatment. In response to 7 microM retinol treatment ornithine decarboxylase activity increased 30%. Retinol-induced ornithine decarboxylase activity was significantly decreased by addition of free radical scavenger (mannitol) or iron chelator (1,10 phenanthroline). In addition the same effect was observed in catalase increased activity and in malondialdehyde concentrations. These results suggest that retinol treatment induced ornithine decarboxylase and catalase activity and increased malondialdehyde concentration. These effects appear to be mediate by ROS.

Animals↗
PubMed2000

Retinol supplementation induces DNA damage and modulates iron turnover in rat Sertoli cells.

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular DNA damage probably involving cellular iron accumulation. Retinol (7 microM) significantly induced DNA single strands breaks, DNA fragmentation and production of 8-oxo-7, 8-dihydro-2'-deoxyguanosine in cultured Sertoli cells. In contrast, lower doses seemed not to induce single-strands break in this experimental model. The breaks in DNA were inhibited by an iron scavenger; and 7 microM retinol treatment modulated iron turnover leading to iron accumulation, suggesting that iron ions were required for the retinol cellular effects. These findings suggest that retinol-induced DNA damage was associated with the modulation of iron turnover, and these characteristics could be responsible for the increased incidence of lung cancer associated with retinoids supplementation.

8-Hydroxy-2'-Deoxyguanosine↗