PubMed Health⌕ Search

Biomedical subjects

A M Barros

Publications and source records attributed to A M Barros.

9 recordsLinked to original sources
PubMed2004

Evaluation of the incorporation ratio of ZnO, PbO and CdO into cement clinker.

Zinc, lead, and cadmium are minor elements that might be brought by wastes to the cement kilns. This work studies the incorporation ratio of ZnO, PbO, and CdO when they are added to the clinker raw material. The cement raw material used in this work was prepared by mixing pure compounds, this choice was made to avoid the effect of other elements and provide a better understanding of the behavior of these metals during the clinkering process. The samples contained additions of 0.05, 0.10, 0.30, 0.50, 0.80 and 1.00 wt.% of a specific oxide (ZnO, PbO, or CdO) to the clinker raw-meal. The chlorine influence in the ZnO incorporation ratio was also evaluated. A device to simulate the thermal cycle imposed on the charge during the clinker production was used to evaluate the incorporation ratio of these oxides as well as thermogravimetric tests. The products of the tests in the simulator device were submitted to X-ray fluorescence chemical analysis or energy disperse scanning (EDS) microprobe analysis. The results led to the conclusions that the evaporation of Zn in cements kilns is due to the chlorine content and the Pb and Cd incorporation ratio stands around 50 wt.%.

Cadmium Compounds↗
PubMed2002

Chloride influence on the incorporation of Cr(2)O(3) and NiO in clinker: a laboratory evaluation.

Co-incinerating wastes in cement rotary kilns may introduce elements not usually found in the raw material into the process or even increase the quantity of some minor elements. Chromium and nickel are present in some electroplating sludges. These wastes are hazardous and must be treated and disposed of in a controlled landfill. The objective of this work was to study the incorporation of chromium and nickel oxides when they were added to clinker raw meal. The clinker raw meal used in this study was prepared by mixing pure compounds in the ratio that made it possible to obtain the same phases of an industrial Portland clinker at the end of the heating process. Twelve samples were prepared by adding 0.05, 0.1, 0.3, 0.5, 0.8 and 1.0wt.% of Cr(2)O(3) and 0.05, 0.1, 0.3, 0.5, 0.8 and 1.0wt.% of NiO to the base charge. Also, four more samples were prepared with additions of 0.6% Cr(2)O(3) and 0.1% NaCl, 0.7% Cr(2)O(3) and 0.1% KCl, 0.8% NiO and 0.1% NaCl and 0.8% NiO and 0.1% KCl. In order to study the Cr and Ni incorporation, thermogravimetric (TG) tests were performed, as well as tests in an assembled experimental device. The products were characterized by X-ray fluorescence chemical analysis, microprobe analyses by energy disperse scanning (EDS) and leaching tests. The results showed that the chromium and nickel added were incorporated into the clinker, even when chlorides were present.

Chromium Compounds↗
PubMed2000

Eggplant (Solanum melongena) infusion has a modest and transitory effect on hypercholesterolemic subjects.

Eggplant (Solanum melongena) is consumed extensively in Brazil. It has been believed that infusion of a powdered preparation of the fruit may reduce serum cholesterol. However, there are few documented reports on its effects on cholesterol metabolism and its possible hypocholesterolemic effect has not been proved by well-controlled studies. The aim of the present study was to observe the effects of S. melongena on the serum cholesterol and triglycerides of 38 hypercholesterolemic human volunteers ingesting S. melongena infusion for five weeks. Thirty-eight hypercholesterolemic subjects receiving either S. melongena infusion (N = 19) or placebo (N = 19) participated in two clinical experiments in which the effect of S. melongena infusion was studied with (N = 16) or without (N = 38) dietary orientation. Total cholesterol and its fractions, triglycerides, and apolipoproteins A and B were measured in blood at the beginning of the experiment and three and five weeks thereafter. No differences were observed compared to control. Intraindividual analysis showed that S. melongena infusion significantly reduced the blood levels of total and LDL cholesterol and of apolipoprotein B. After dietary orientation, no intra- or intergroup differences were seen for any of the parameters analyzed. The results suggest that S. melongena infusion had a modest and transitory effect, which was not different from that obtained with standard orientation for dyslipidemia patients (diet and physical activities).

Adult↗
PubMed1999

Incidence and distribution of postcranial fractures in the prehistoric population of San Pedro de Atacama, Northern Chile.

Trauma incidence analysis in skeletal populations has been very popular among skeletal biologists during the last two decades. In this context, the work of Lovejoy and Heiple ([1981] Am. J. Phys. Anthropol. 55:529-541) has been quoted as a landmark because their analysis rested on a populational approach, avoiding simple assumptions about cause and etiology. In this study, we apply to the prehistoric population of San Pedro de Atacama, northern Chile, an approach similar to that carried out by Lovejoy and Heiple (1981). The results obtained point to a peak of risk of fractures among old people, estimated age around 45 years. The distribution of fractures by sex and age suggests that the prevailing etiology is related to accidents and not violence. When the frequencies of fractures are compared, the Libben population shows a much higher incidence than the Atacamenean population. It is suggested that this difference can be explained by peculiarities of the subsistence economies of the two populations.

Adolescent↗
PubMed1999

Integration of Trypanosoma cruzi kDNA minicircle sequence in the host genome may be associated with autoimmune serum factors in Chagas disease patients.

Integration of kDNA sequences within the genome of the host cell shown by PCR amplification with primers to the conserved Trypanosoma cruzi kDNA minicircle sequence was confirmed by Southern hybridization with specific probes. The cells containing the integrated kDNA sequences were then perpetuated as transfected macrophage subclonal lines. The kDNA transfected macrophages expressed membrane antigens that were recognized by antibodies in a panel of sera from ten patients with chronic Chagas disease. These antigens barely expressed in the membrane of uninfected, control macrophage clonal lines were recognized neither by factors in the control, non-chagasic subjects nor in the chagasic sera. This finding suggests the presence of an autoimmune antibody in the chagasic sera that recognizes auto-antigens in the membrane of T. cruzi kDNA transfected macrophage subclonal lines.

Animals↗
PubMed1991

Separation and simultaneous high-performance liquid chromatographic determination of benzocaine and benzyl benzoate in a pharmaceutical preparation.

A simple reversed-phase high-performance liquid chromatographic method suitable for the simultaneous determination of benzocaine and benzyl benzoate in dermatological preparations is described. An internal standard method was employed, using C18 "bonded phase" silica column and a mobile phase consisting of acetonitrile - water (40:60, v/v), with absorption of the column effluent monitored at 254 nm. No sources of interference were observed. The simultaneous determination of both compounds by the method described is rapid and accurate.

Benzoates↗
PubMed1989

The effect of short-wavelength ultraviolet light on antigens, lectin receptors and the ultrastructure of Crithidia fasciculata.

Crithidia fasciculata is an important trypanosomatid parasite commonly affecting insects and is used extensively as a model for the study of the biochemistry, ultrastructure and organization of the kDNA network of trypanosomatids. The present study describes the evolution of UV-induced morphological changes detectable by transmission electron microscopy in Crithidia fasciculata. Although only rare and minor changes in kinetoplast DNA were demonstrable 7 h after UV irradiation, alterations of this organelle were present in almost all flagellates observed 24 h and 48 h after irradiation. Other cell structures were apparently undamaged. Ultrastructural changes in kDNA did not correspond to changes in antigenicity of protein bands in western blotting against serum from Chagas' disease patients or in the presence of 3 different lectin receptors on the surface of the parasite.

Animals↗
PubMed1988

UV-induced growth inhibition in the trypanosomatid Crithidia fasciculata.

The effects of short ultraviolet (253 nm) radiation on the growth of the trypanosomatid flagellate Crithidia fasciculata were studied in liquid medium and nutrient agar plates. Cell duplication was completely inhibited after exposure of the flagellates to doses equal to or higher than 50 J/m2. The UV-induced lag period was dose-dependent. Survival was reduced to 1% after exposure of the parasites to 200 J/m2. Ultrastructural changes after the lag period were studied by transmission electron microscopy. Changes of the kinetoplast network structure and sometimes of the mitochondrial matrix were observed. The existence of DNA repair mechanisms in this protozoan is discussed.

Animals↗