Polymerase chain reaction-single strand conformation polymorphism applied to sex identification of Accipiter cooperii

Determination of sex in birds is valuable for studying population dynamics and structure, habitat use, behavior and mating systems. The purpose of the present study was to optimize a DNA-based methodology to allow the sex identification in Accipiter cooperii nestlings. Chromo-helicase-DNA-binding (CHD1) gene was used in this work as a marker for sex identification. CHD-W and CHD-Z sequences should present length and/or sequence differences providing a way to identify gender. We used a non-invasive method for DNA extraction from feathers and performed polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method. The length difference between CHD-W and CHD-Z amplified fragments observed by electrophoresis in conventional agarose gel was not enough to provide a clear differentiation between males and females. However, patterns obtained by PCR-SSCP differentiated undoubtedly males and females in A. cooperii. This tool provides a precise gender identification assay and will be applied to confirm and refine morphometrically based sexing techniques used in the field.     

Some geological characteristics in a regolith-limey shale rock profile through natural radionuclides distribution

The objective of this work is to study some geological characteristics in a regolith-rock profile by analyzing the distribution of natural radionuclides along the profile by high resolution gamma ray spectrometry. The concentrations of radionuclides reflect some mineralogical characteristics of the rock matrix and also more recent events, such as weathering and erosion. The samples were collected in an abandoned limestone mine, in the city of Sapopema, Paraná State, Brazil. The stratigraphy is represented by an alternation of decimetric limestone layers, bituminous shale and some rhythmite layers. The ratios eTh/K obtained for all samples of the studied profile have equivalent values, indicating similar mineralogical characteristics of their detritic components. The ratio eTh/eU corroborates the fact that regolith samples belong to a much more oxidized environment, favoring the leaching of uranium. These results show that the measurement of radionuclide distribution in rocks and soils may be an important tool for the analysis of geological characteristics, such as mineralogy and oxidizing conditions.     

In vitro study of P-glycoprotein induction as an antidotal pathway to prevent cytotoxicity in Caco-2 cells

The Caco-2 cell line is a reliable in vitro model for predicting drug intestinal absorption and P-glycoprotein (P-gp)-mediated excretion in humans. Recent in vivo studies suggested the induction of P-gp as a cellular protection tool against paraquat poisoning, through the increase in its pulmonary and intestinal excretion. Thus, the aim of the present work was to evaluate P-gp expression and activity in Caco-2 cells exposed to doxorubicin (a known P-gp inducer) and to correlate these changes with paraquat toxic effects. Cytotoxicity of doxorubicin (0–100 μM) and paraquat (0–1,000 μM) was evaluated for a maximum period of 96 h. In doxorubicin-exposed cells, P-gp expression and transport activity were evaluated by flow cytometry, using a fluorescein isothiocyanate–conjugated antibody and the P-gp fluorescent subtract rhodamine 123, respectively. A significant increase in P-gp expression was observed as soon as 6 h after exposure to 5 μM doxorubicin. P-gp activity also increased after 6 h, but only at higher doxorubicin concentrations (over 50 μM). Paraquat (0–5,000 μM) cytotoxicity was then evaluated with or without previous exposure of the cells to doxorubicin (5–100 μM, a concentration range causing both an increase in P-gp expression and activity). Under P-gp induction, a significant reduction in paraquat cytotoxicity was observed. Furthermore, when these cells were incubated with a specific P-gp inhibitor (UIC2 antibody) the doxorubicin protective effects were blocked, confirming the involvement of P-gp in the reduction in paraquat cytotoxicity. In conclusion, the human Caco-2 cell line model can be used for the study of P-gp induction as an antidotal pathway against substrates of this transporter system.     

Protective effects of Hibiscus tiliaceus L. methanolic extract to V79 cells against cytotoxicity and genotoxicity induced by hydrogen peroxide and tert-butyl-hydroperoxide

Plants of the genus Hibiscus thrives produce a diversity of molecules with bioactive properties. In a previous study of Hibiscus tiliaceus L. methanolic extract (HME) using bacteria and yeast, as test media, it has been shown that HME strongly inhibited the mutagenic action of H₂O₂ or tert-butyl-hydroperoxide (t-BHP). Here, our interest is to evaluate the genotoxicity and the antigenotoxic/antimutagenic properties of HME using oxidative challenge with H₂O₂ and t-BHP in V79 cells. We determined cytotoxicity using clonal survival assay; evaluated DNA damage using the comet assay and the micronucleus test in binucleated cells besides of the lipid peroxidation degree and the reduced glutathione content. We examined the ability of HME in quenching hydroxyl radical by means of a HPLC-based method utilizing the hypoxanthine/xanthine oxidase assay. At concentrations ranging from 0.001 to 0.1 mg/mL, HME was not cytotoxic, genotoxic or mutagenic. Treatment with non-cytotoxic concentrations of HME increased cell survival after H₂O₂ and t-BHP exposure and prevented DNA damage. The pre-treatment with HME also was able to decrease the mutagenic effect of these genotoxins, evaluated using the micronucleus test. HME prevented the increase in lipid peroxidation and decrease in GSH content in response to the oxidative challenge. Therefore, the ability in preventing against H₂O₂- and t-BHP-induced GSH depletion and lipid peroxidation was probably a major contribution to the cytoprotective effects. Moreover, HME acts as a hydroxyl radical scavenger. In summary, HME did not have a harmful or inhibitory effect on the growth of V79 cells and presented antioxidant activity, consequently, both antigenotoxic and antimutagenic effects against oxidative DNA damage.     

Urinary nickel as bioindicator of workers' Ni exposure in a galvanizing plant in Brazil

Objectives: We measured urinary nickel (U-Ni) in ten workers (97 samples) from a galvanizing plant that uses nickel sulfate, and in ten control subjects (55 samples) to examine the association between occupational exposure to airborne Ni and Ni absorption. Methods: Samples from the exposed group were taken before and after the work shift on 5 successive workdays. At the same time airborne Ni (A-Ni) was measured using personal samplers. Ni levels in biological material and in the airborne were determined by a graphite furnace atomic absorption spectrometry validated method. In the control group the urine samples were collected twice a day, in the before and after the work shift, on 3 successive days. Results: Ni exposure low to moderate was detected in all the examined places in the plant, the airborne levels varying between 2.8 and 116.7 μg/m³ and the urine levels, from samples taken postshift, between 4.5 and 43.2 μg/g creatinine (mean 14.7 μg/g creatinine). Significant differences in U-Ni creatinine were seen between the exposed and control groups (Student's t test, P ≤ 0.01). A significant correlation between U-Ni and A-Ni (r = 0.96; P ≤ 0.001) was detected. No statistical difference was observed in U-Ni collected from exposed workers in the 5 successive days, but significant difference was observed between pre- and postshift samples. Conclusions: Urinary nickel may be used as a reliable internal dose bioindicator in biological monitoring of workers exposed to Ni sulfate in galvanizing plants regardless of the day of the workweek on which the samples are collected. Received: 28 January 1999 / Accepted: 10 July 1999     

Natural transmission of foot-and-mouth disease virus between African buffalo (Syncerus caffer) and impala (Aepyceros melampus) in the Kruger National Park, South Africa

VP1 gene sequences of SAT-2 type foot-and-mouth disease (FMD) viruses recovered from impala and African buffalo in the Kruger National Park (KNP) were used to determine intra- and interspecies relationships of viruses circulating in these wildlife populations. On this basis five distinct lineages of SAT-2 virus were identified in routine sampling of oesophageopharyngeal epithelium from buffalo between 1988 and 1996. Different lineages were associated with discrete geographic sampling localities. Over the period 1985-95, four unrelated epizootics occurred in impala in defined localities within the KNP. Evidence for natural transmission of FMD between buffalo and impala is presented for the most recent 1995 outbreak, with data linking the 1985 and 1988/9 impala epizootics to viruses associated with specific buffalo herds.     

Cu2+-induced isoproterenol oxidation into isoprenochrome in adult rat calcium-tolerant cardiomyocytes

Sustained high levels of circulating catecholamines may induce cardiotoxicity. There is increasing evidence that this could result from catecholamine oxidation into aminochromes, which is catalyzed by transition metals. In fact, it has already been shown that copper-induced oxidation of the beta-agonist isoproterenol decreases the viability of isolated cardiomyocytes. Thus, the aim of this work was to contribute for the clarification of the mechanisms underlying the toxic effects of isoproterenol, Cu2+ and their concomitant effect in isolated rat cardiomyocytes. Freshly isolated calcium-tolerant cardiomyocytes from adult rat were incubated with 1 mM isoproterenol, 20 microM Cu2+ or with both during 4 h. Isoproterenol and its aminochrome (isoprenochrome), and reduced and oxidized glutathione were measured at each hour in the incubation medium and in the cells. The intracellular activities of the selenium-dependent glutathione peroxidase, glutathione reductase, and glutathione-S-transferase were determined after 4 h of incubation. Isoprenochrome was found in both cells and incubation medium in samples incubated with isoproterenol alone. However, in the isoproterenol plus Cu2+ samples, a greater depletion of isoproterenol accompanied by a proportional increase of isoprenochrome was observed. This higher ISO oxidation resulted in the depletion of intracellular glutathione and in the release of oxidized glutathione to the incubation medium. The content of total glutathione (intra- and extracellular) and the intracellular activity of the selenium-dependent glutathione peroxidase, glutathione reductase, and glutathione-S-transferase were also decreased in the isoproterenol plus Cu2+ samples. These results seem to indicate that the oxidative stress resulting from catecholamine/transition metal association may contribute to catecholamine cardiotoxicity.     

Health inequality indicators: a discussion of some methodological approaches as applied to neonatal mortality in the Municipality of Rio de Janeiro, 2000

Epidemiology has investigated the relationship between health status and different social and economic factors ever since the field emerged. Studies have consistently shown that the population's health status bears a strong social gradient, invariably unfavorable to the less privileged groups. Increasing interest in understanding and characterizing health inequalities has broadened the discussion in the recent literature on appropriate concepts and methodological procedures for measuring differences in health status according to socioeconomic level. This study presents a critical assessment of health inequality indicators, focusing on the following: the redistribution principle and its application to health status; the influence of income inequality; epidemiological and statistical approaches to the problem; and evaluation of health system performance in reducing health inequalities. As an example, inequalities in the neonatal mortality rate are analyzed in the city of Rio de Janeiro, Brazil, 2000, according to the mother's level of schooling, reviewing the minimum requisites for defining an adequate health inequality indicator.