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J C Moreira

Publications and source records attributed to J C Moreira.

31 records · Page 2Linked to original sources
PubMed2000

Cholinesterase activities determination in frozen blood samples: an improvement to the occupational monitoring in developing countries.

1. Studies were carried out on rural workers in Brazil to determine the decrease in the activity of plasma butyrylcholinesterase (BChE), erythrocyte cholinesterase (AChE) associated with exposure to organophosphorus pesticides (OP). The goal of this work is to help prevent injury to these workers. 2. In developing countries the distance between area of pesticide use and reference laboratories is a drawback for analytical techniques, since cholinesterase activity determinations require fresh blood samples. Field methodologies can be a useful alternative to laboratory tests, however they are not as sensitive as those found in laboratories. 3. The modification of Ellman's Method presented in this paper allows blood samples to be frozen and maintain enzymatic stability: 7 days for AChE and 3 days for BChE. The proposed method is also more sensitive than Ellman's Method Modified by Magnotti (EMMM). 4. The results suggest that the Ellman Method Modified by Oliveira-Silva (EMMOS) is valid for monitoring procedures. This method represents an important contribution to the process of monitoring OP exposures, since the evaluations no longer have to be conducted near the site of OP use.

Acetylcholinesterase↗
PubMed2000

Retinol-induced changes in the phosphorylation levels of histones and high mobility group proteins from Sertoli cells.

Chromatin proteins play a role in the organization and functions of DNA. Covalent modifications of nuclear proteins modulate their interactions with DNA sequences and are probably one of the multiple factors involved in the process of switch on/off transcriptionally active regions of DNA. Histones and high mobility group proteins (HMG) are subject to many covalent modifications that may modulate their capacity to bind to DNA. We investigated the changes induced in the phosphorylation pattern of cultured Wistar rat Sertoli cell histones and high mobility group protein subfamilies exposed to 7 microM retinol for up to 48 h. In each experiment, 6 h before the end of the retinol treatment each culture flask received 370 KBq/ml [32P]-phosphate. The histone and HMGs were isolated as previously described [Moreira et al. Medical Science Research (1994) 22: 783-784]. The total protein obtained by either method was quantified and electrophoresed as described by Spiker [Analytical Biochemistry (1980) 108: 263-265]. The gels were stained with Coomassie brilliant blue R-250 and the stained bands were cut and dissolved in 0.5 ml 30% H2O2 at 60oC for 12 h. The vials were chilled and 5.0 ml scintillation liquid was added. The radioactivity in each vial was determined with a liquid scintillation counter. Retinol treatment significantly changed the pattern of each subfamily of histone and high mobility group proteins.

Animals↗
PubMed1999

Phenotype modulation of cellular UV-sensitivity.

Mammalian cell shape is critically important to cell differentiation, apoptosis, cell division, and growth arrest. In the present study we examined the relationship among cell density, cell phenotype (which include shape and coupling) and cell survival using the human A549, H596 and H520 non-small cell lung carcinoma lines. Thus, cells from monolayers, aggregated and suspended cultures at different densities were exposed to UV-radiation and both the density and the phenotype of the cells induce shifts in cellular growth rate. Except in suspended cultures, we observed a UV-sensitivity closely related to the proliferative status of the cells. The variability of the cellular response to UV were investigated taking into account the shape and the coupling potential of the cell lines, suggesting that an intercellular-contact mechanism provides further protection against UV-radiation damage.

Carcinoma, Non-Small-Cell Lung↗
PubMed1998

Cancer cluster among young Indian adults living near power transmission lines in Bom Jesus do Tocantins, Pará, brazil.

A case study was carried out to explore the occurrence of a cancer cluster in 1992 among young indian adults adults living in an Amazonian village near two 500 kV power transmission lines that began operating a decade ago. Current blood levels of DDT and organophosphorus pesticides and metal levels in hair samples were measured. Extremely low magnetic field exposure was determined during current daily activities carried out by the Indian villagers. Taking into account the cancer incidence rates in different Brazilian cities, the probability of the occurrence of this cluster by chance was considered remote (p< 0.003, Poisson distribution). High blood levels of p,p'-DDT (median levels ranging from 26 to 58 ppb) were observed. As a whole, this community showed a pattern of low exposure to organophosphorus pesticides, and high recent exposure was only observed in a few blood samples. Continuous exposure to extremely low electromagnetic fields originated in the power transmission lines (which reached 95.0 mG under the lines) was observed on several opportunities during daily activities carried out by Indian villagers. Further observational studies should evaluate the interaction between exposure to extremely low electromagnetic fields and prior exposure to tumor initiators in cancer development.

Adolescent↗
PubMed1996

Threats by heavy metals: human and environmental contamination in Brazil.

An overview of some aspects of the current situation in Brazil, as regards environmental and human contamination by chemicals is presented. Special attention is given to those problems caused by heavy metals (mercury, cadmium, zinc, arsenic and chromium) used in industrial activities and in goldmining. Social and economical influences are also briefly discussed.

Arsenic↗
PubMed1995

[Hexachlorocyclohexane contamination in urban areas of the south eastern region of Brazil].

A factory for producing the pesticide hexachlorocyclohexane (HCR) in its technical grade (mix of the alpha, beta, gamma, and delta isomers), that belonged to the former Institute of Malaria Sciences, then Ministry of Education and Health, located in the "Cidade dos Meninos", county of Duque de Caxias, State of Rio de Janeiro, was closed down in 1955. Part of its production and wastes - many tons this mix - were left behind on the site. The action of winds and rain as well as the movement of the local inhabitants - approximately 1,000 people, including 400 children, have caused the scaltering of this agent. Blood specimens from the inhabitants showed a high human contamination levels, with the highest concentration (beta isomers) being found in people living within a 100 meter radius of the ruin of the factory. Local soil and pasture samples taken at distances of less than 100 m from the ruin of the former factory showed HCH isomer concentrations of the order of thousands of ppb, thus providing evidence of high environmental contamination.

Brazil↗
PubMed1989

Effect of proline administration on rat behavior in aversive and nonaversive tasks.

Sustained levels of proline comparable to those of human type II hyperprolinemia were achieved in blood and brain of rats subcutaneous proline administration twice a day from the 6th till the 28th day of life. Control rats were treated with saline in the same volumes. Behavioral studies using aversive and nonaversive tasks were performed one week or one month after treatment. Proline treatment did not affect rats' performance in the inhibitory avoidance task, but reduced significantly habituation in the open field. Our results seem to indicate that early postnatal administration of proline to rats affects habituation to a novel environment. If this happens to be so the present tendency to consider hyperprolinemia as a benign condition should be revised.

Age Factors↗
PubMedDate not supplied

Protein kinase C-mediated in vitro invasion of human glioma cells through extracellular-signal-regulated kinase and ornithine decarboxylase.

We investigated the involvement of protein kinase C (PKC) in the in vitro invasiveness of the A-172, U-87 and U-373 human glioma cell lines, as well as the role of ornithine decarboxylase (ODC) and/or extracellular-signal-regulated kinase (ERK) in the actions of PKC. Thus, cells were treated under serum-free conditions with the PKC activator phorbol 12-myristate 13-acetate (PMA), or with the PKC inhibitors bisindolylmaleimide I (GF 109203X) or calphostin C in the absence or presence of the ODC inhibitor D,L-alpha-difluoromethylornithine (DFMO), and/or the mitogen-activated protein kinase/extracellular-signal-regulated kinase inhibitor 2'-amino-3'-methoxyflavone (PD 098059). Subsequently, cells were assessed for membrane-type 1 matrix metalloproteinase (MT1-MMP) mRNA contents, 72-kD latent, and 59/62-kD activated matrix metalloproteinase 2 (MMP-2) in conditioned media, as well as invasiveness. For these purposes, we used Northern blot analysis, gelatine zymography, and an in vitro filter invasion assay, respectively. Data were related to those found with untreated cells. PKC activity was 2- to 3-fold stimulated by PMA (100 nM for 30 min), and about 2-fold inhibited by calphostin C (40 nM for 2 h) or GF 109203X (5 microM for 20 min). This was accompanied by a similar increase or decrease, respectively, in MT1-MMP mRNA expression, 59/62-kD MMP-2 activity, and in vitro invasion. Inhibition of ODC activity (about 2-fold by 24 h DFMO 5 mM), ERK activation (almost completely by 20 min PD 098059 50 microM), or both these enzymes simultaneously led to a reduction by about half in levels of MT1-MMP mRNA, 59/62-kD MMP-2 activity, and invasion in untreated as well as PMA-stimulated cells. The use of these compounds did not significantly alter the inhibitory effects of GF 109203X or calphostin C. Modulation of PKC and/or ERK activity resulted in corresponding changes in ERK and/or ODC activities, but interference with ODC affected neither ERK nor PKC. Our data suggest a regulatory role for PKC, in co-operation with ERK and ODC, in glioma cell invasion, by modulation of MT1-MMP mRNA expression and MMP-2 activation.

Culture Media, Conditioned↗
PubMedDate not supplied

Atmospheric carcinogens in Rio de Janeiro during the summer of 1998/99: benzo[a]pyrene and benzene.

Rio de Janeiro, the second largest city in Brazil, is affected by severe pollution episodes and presents a high respiratory cancer incidence in comparison with the rest of the country. To monitor atmospheric pollution during the summer of 1998/1999 and to estimate the impact of organic pollution on public health, we determined the levels of two carcinogenic organic chemicals, benzo[a]pyrene and benzene, in four distinct sites throughout the city. A review of the levels recorded in other urban areas worldwide during the last ten years indicates that the benzo[a]pyrene (< or = 0.70 ng/m3) and benzene (< or = 11 micrograms/m3) concentrations found in Rio are relatively low. The highest levels were generally recorded in developing Asian countries, whereas the lowest values were found in North America. Unlike urban areas in temperate zones, pollution derived from domestic heating is minor in Rio de Janeiro, where most of the benzo[a]pyrene and benzene pollution originates from vehicular traffic. The quite distinct fuels used in light-duty vehicles in Brazil, combined with strong light incidence and increased rainfall during the summer, also contribute to diminish the levels of such pollutants.

Air Pollution↗
PubMedDate not supplied

[Occupational lead exposure assessment: a proposal for a strategy to monitor prevention of clinical and subclinical effects].

In developing countries, lead-acid battery factories are one of the heaviest consumers of lead. Due to lead's toxicological properties and prevalent working conditions in such factories, workers are subject to high exposure and health risk. This study discusses results obtained by lead exposure assessment of workers from a Rio de Janeiro battery factory, in light of Brazilian legislation and recent scientific data. Evaluation methods used were environmental (personal air sampling) and biological (determination of lead in blood, Pb-B) monitoring, showing a high personal exposure both in air (>0.1 mg/m3) and blood (55% of Pb-B >25 microg/dl). These results confirmed the inefficiency of current control measures, with a possible 46% of workers presenting a Pb-B range of 25-60 microg/dl in risk areas. Recent data suggest that Pb-B levels above 25 microg/dl are related to subclinical alterations in human body that should be investigated during clinical examination. Finally, we propose a strategy based on environmental and biological monitoring to prevent both clinical and subclinical effects.

Air Pollutants, Occupational↗
PubMedDate not supplied

[Are some Brazilian population groups subject to endocrine disrupters?].

Several chemical substances suspected of endocrine disruption are currently being used in industrial and agricultural activities in Brazil. This paper presents analytical data showing contamination of some population groups by these substances. Virtually nothing is known about the related health effects, highlighting the need to implement a national program to evaluate such impacts.

Brazil↗
PubMedDate not supplied

[Limits in the applicability of urine delta aminolevulinic acid determination as a screening test in the evaluation of occupational lead poisoning].

The relationship between concentrations of ALA-U and Pb-S for two groups of workers is reported. The first group consisted of workers from a telephone company, and the second, of workers from battery factories with average Pb-S equivalent to 17.3 (g/dl (6.2-39.4) and 61.5 (g/dl (41.1-91.0), respectively. The aim of this study was to evaluate the utilization of ALA-U levels as a screening test for different levels of lead in blood by means of High Performance Liquid Chromatography (HPLC) and of spectrophotometry. A significant correlation was found between measured ALA and levels of blood lead (R = 0.739 - first group; R = 0.902 - second group; p < 0.001). The validity of ALA-U test to evaluate different levels of lead in blood was also studied. By using ALA levels of 3mg/g creatinine as a threshold to detect levels of lead in blood equal to or higher than 20 (g/dl, the test results, for the workers in the first group, showed sensibility of 92% and specificity of 90%. In both groups, the false positives as well the false negatives were lower than 10% which was enough to validate the test.

Adult↗