Mutagenic activity detected by the Ames test in river water under the influence of petrochemical industries

The present study was carried out on the waters of the Caí River (Rio Grande do Sul, Brazil) in an area under the influence of a petrochemical industrial complex, as the continuation of a study in which the mutagenic activity of water samples was evaluated in the internal area of this complex. In the previous study, the release of inducing substances was detected, revealing the need for a full analysis of the real ecological impact of the industrial complex on the river. Water samples from different sites along the Caí River were subjected to the Ames test during a study of 20 months duration for the detection of possible mutagens. Strains TA100 and TA98 were used for initial sample screening in the presence and absence of the S9 mix at a standard dose of 2000 microliters/plate. When positive activity (values equal to twice the spontaneous mutation rate) and/or cytotoxic activity (cell survival below 60%) was detected, the dose-response relationship was studied. Thirty-four percent of the samples tested were mutagenic, with different values according to collection site. Of the total number of positive responses, 6% were obtained for samples collected at the blank site upstream from the area studied, 82% at sites closest to the industrial complex, and 12% in downstream areas. Strain TA98 was the most sensitive in assays with no metabolic activation. A low frequency of induction (2%) was observed for strain TA102. Application of the Ames test permitted the delimitation of three areas of influence of the petrochemical industrial complex, and the test proved to be adequate for the detection of contaminants from the petrochemical industry.     

Desaturation of fatty acids inTrypanosoma cruzi

Uptake and metabolism of saturated (16∶0, 18∶0) and unsaturated [18∶1(n−9), 18∶2(n−6), 18∶3(n−3)] fatty acids by cultured epimastigotes ofTrypanosoma cruzi were studied. Between 17.5 and 33.5% of the total radioactivity of [1-¹⁴C]labeled fatty acids initially added to the culture medium was incorporated into the lipids ofT. cruzi and mostly choline and ethanolamine phospholipids. As demonstrated by argentation thin layer chromatography, gas liquid chromatography and ozonolysis of the fatty acids synthesized, exogenous palmitic acid was elongated to stearic acid, and the latter was desaturated to oleic acid and 18∶2 fatty acid. The 18∶2 fatty acid was tentatively identified as linoleic acid with the first bond in the Δ9 position and the second bond toward the terminal methyl end. Exogenous stearic acid was also desaturated to oleic and 18∶2 fatty acid, while oleic acid was only converted into 18∶2. All of the saturated and unsaturated fatty acids investigated were also converted to a small extent (2–4%) into polyunsaturated fatty acids. No radioactive aldehyde methyl ester fragments of less than nine carbon atoms were detected after ozonolysis of any of the fatty acids studied. These results demonstrate the existence of Δ9 and either Δ12 or Δ15 desaturases, or both, inT. cruzi and suggest that Δ6 desaturase or other desaturases of the animal type are likely absent in cultured forms of this organism.     

Effect of a strong magnetostatic field on proliferation of duodenal epithelial cells in mice

The proliferative activity of duodenal epithelial cells in mice subjected to the effect of a 1000-Oe magnetostatic field (MSF) was studied. It was established that the one-day effect of a strong MSF causes transient disturbance of cell division processes. This is indicated by changes in the mitotic index and content of cells in the duodenal crypt, and also by the increase in the number of pathological forms of mitoses with a predominance of chromosomal damages.     

On the metabolic characteristic of hybrids Shigella flexneri x Escherichia coli devoid of their ability for intracellular multiplication in the epithelial cells. I. Glycolysis

In order to evaluate the effects of ultrasonic nebulization on airway resistance in respiratory failure, ten patients requiring mechanical ventilation for acute pulmonary failure were each ventilated with two humidification systems, one producing inspired air saturated with vapour at 35 degrees C, the other nebulizing water droplets ultrasonically. There was no statistically significant difference in pulmonary resistance at inspiratory flow rates of 40, 60, AND 80 1/min. A separate comparison between humidifiers in those patients with the highest resistances did not reveal any difference in response to method of humidification. In contrast to studies in other contexts, these data fail to show any significant difference, from the standpoint of effects on resistance, in the use of ultrasonic mist humidification during mechanical ventilation for respiratory failure.     

Carbohydrate tolerance in the puerperium during suppression of lactation with bromocriptine and oestrogens

The influence of bromocriptine on carbohydrate tolerance in the puerperium was examined and its effects compared with those of an oestrogenic compound. Sixteen patients were studied in each group. The controls consisted of 16 women who were breast-feeding. Compared with the controls, no significant difference was found in the oral glucose tolerance test in patients who had oestrogen, but blood glucose values in women receiving bromocriptine were significantly lower. Inhibition of lactation with bromocriptine may obscure abnormal glucose tolerance.     

Glutamate dehydrogenase, alanine aminotransferase, thymidine kinase, and arginase in fetal and adult human and rat liver

In fetal livers of both man and rat thymidine kinase activity was 12 times higher than in the adult, glutamate dehydrogenase and arginase were present at 20-50% of their adult values, whereas alanine aminotransferase activity was only an insignificant fraction of that in the adult. Although the developmental changes for the four enzymes were quantitatively similar in both species, qualitatively there were some significant differences. In adult human liver, glutamate dehydrogenase activity was distributed almost equally between the cytosol and particles; the concentration of only the soluble enzyme increased after birth. In rat liver, glutamate dehydrogenase remained exclusively a particulate enzyme. The soluble hepatic alanine aminotransferase activity rose in both species after birth (from less than 2 U/g to 41-57 U/g, respectively). Thymidine kinase was wholly soluble in the fetal livers; only in adult human liver was additional activity (at least 50% of the total) found in the particles. Arginase isozymes, identical and apparently the same single isozyme in fetal and adult rat liver, show an ontogenetic change in man. A shift from a single form, common to human fetal liver and fetal kidney, to at least two variants in adult human liver, indicates another complexity of the fully differentiated liver in man.