Prenatal exposure to metals modified DNA methylation and the expression of antioxidant- and DNA defense-related genes in newborns in an urban area.

The developmental period in utero is a critical window for environmental exposure. Epigenetic fetal programming via DNA methylation is a pathway through which metal exposure influences the risk of developing diseases later in life. Genetic damage repair can be modified by alterations in DNA methylation, which, in turn, may modulate gene expression due to metal exposure. We investigated the impact of prenatal metal exposure on global and gene-specific DNA methylation and mRNA expression in 181 umbilical cord blood samples from newborns in Mexico City. Global (LINE1) and promoter methylation of DNA-repair (OGG1 and PARP1) and antioxidant (Nrf2) genes was evaluated by pyrosequencing. Prenatal metal exposure (As, Cu, Hg, Mn, Mo, Pb, Se, and Zn) was determined by ICP-MS analysis of maternal urine samples. Multiple regression analyses revealed that DNA methylation of LINE1, Nrf2, OGG1, and PARP1 was associated with potentially toxic (As, Hg, Mn, Mo, and Pb) and essential (Cu, Se, and Zn) elements, and with their interactions. We also evaluated the association between gene expression (mRNA levels quantified by p-PCR) and DNA methylation. An increase in OGG1 methylation at all sites and at CpG2, CpG3, and CpG4 sites was associated with reduced mRNA levels; likewise, methylation at the CpG5, CpG8, and CpG11 sites of PARP1 was associated with reduced mRNA expression. In contrast, methylation at the PARP1 CpG7 site was positively associated with its mRNA levels. No associations between Nrf2 expression and CpG site methylation were observed. Our data suggest that DNA methylation can be influenced by prenatal metal exposure, which may contribute to alterations in the expression of repair genes, and therefore, result in a lower capacity for DNA damage repair in newborns.

Metal Ions Activate the Human Taste Receptor TAS2R7.

Divalent and trivalent salts exhibit a complex taste profile. They are perceived as being astringent/drying, sour, bitter, and metallic. We hypothesized that human bitter-taste receptors may mediate some taste attributes of these salts. Using a cell-based functional assay, we found that TAS2R7 responds to a broad range of divalent and trivalent salts, including zinc, calcium, magnesium, copper, manganese, and aluminum, but not to potassium, suggesting TAS2R7 may act as a metal cation receptor mediating bitterness of divalent and trivalent salts. Molecular modeling and mutagenesis analysis identified 2 residues, H943.37 and E2647.32, in TAS2R7 that appear to be responsible for the interaction of TAS2R7 with metallic ions. Taste receptors are found in both oral and extraoral tissues. The responsiveness of TAS2R7 to various mineral salts suggests it may act as a broad sensor, similar to the calcium-sensing receptor, for biologically relevant metal cations in both oral and extraoral tissues.

Health risk due to chronic heavy metal consumption via cow's milk produced in Puebla, Mexico, in irrigated wastewater areas.

The aim of this study was to determine the heavy metals content of milk from cows fed with forage irrigated with waste water from industrial sources and the health risk to children. Milk samples were taken from milk collection tanks of eight localities in the state of Puebla. On average, the heavy metals in the milk had the following order Zn> As> Pb > Cr> Cu > Ni. Pb (0.03 mg kg-1) exceeded the Codex limits. For As the hazard index was 8.0 ± 0.4, which is far above 1. On the other hand, the individual risk of cancer showed a descending order Cr> As > Pb, while the risk of total cancer (0.004 ± 0.002) indicated that the combined effect of heavy metals created a serious risk for girls and children.

Determinação da CL 50 aguda em Colossoma macropomum expostos à prata coloidal

A prata é um elemento que foi usado durante muitos anos e atualmente é amplamente usado pelas suas propriedades antimicrobianas. Nas últimas décadas, as nanopartículas de prata têm oferecido um campo muito amplo de pesquisa pelas suas extraordinárias atividades biológicas e propriedades físico-químicas como fonte de interesses para novas aplicações além do fato de não induzir resistência bacteriana. No presente estudo foi determinada a concentração letal 50 da prata coloidal em tambaqui (Colossoma macropomum) de forma aguda, 48 horas.

Determinação da CL 50 aguda em Colossoma macropomum expostos à prata coloidal

A prata é um elemento que foi usado durante muitos anos e atualmente é amplamente usado pelas suas propriedades antimicrobianas. Nas últimas décadas, as nanopartículas de prata têm oferecido um campo muito amplo de pesquisa pelas suas extraordinárias atividades biológicas e propriedades físico-químicas como fonte de interesses para novas aplicações além do fato de não induzir resistência bacteriana. No presente estudo foi determinada a concentração letal 50 da prata coloidal em tambaqui (Colossoma macropomum) de forma aguda, 48 horas.(AU)

Toxic effects of the ingestion of water-soluble elements found in soil under the atmospheric influence of an industrial complex.

In this study, we investigated the toxic effects of water-soluble elements from a contaminated soil via gavage in a single dose, simulating a geophagy event. The contaminated soil was collected in a field located in an industrial complex, and the control soil was collected in a reference area. Metabolic and behavioral parameters in Wistar male rats were measured after 24 and 96 h of gavage. After 96 h, the major organs were weighed, blood was collected to check hematological parameters, the bone marrow was taken for the micronucleus test, and the liver was used for evaluating the total antioxidant capacity, lipoperoxidation and protein carbonylation. Animals exposed to contaminated soil presented a few significant alterations by comparison with control animals: TBARS and protein carbonyl levels increased, the relative weight of the kidneys increased, metabolic parameters (body weight gain, food intake, water consumption, urine and feces production) depressed and there was behavioral alteration. These findings suggest that soils impacted by atmospheric contaminants can affect the organism physiological status jeopardizing the health of populations living in industrial areas. Finally, this study reassures that ingestion of potentially contaminated soils, even for short periods of time, can cause health risks.

Acetylcholinesterase activity and antioxidant capacity of zebrafish brain is altered by heavy metal exposure.

Pollution is a world problem with immeasurable consequences. Heavy metal compounds are frequently found as components of anthropogenic pollution. Here we evaluated the effects of the treatment with cadmium acetate, lead acetate, mercury chloride, and zinc chloride in acetylcholinesterase activity and gene expression pattern, as well as the effects of these treatments in antioxidant competence in the brain of an aquatic and well-established organism for toxicological analysis, zebrafish (Danio rerio, Cyprinidae). Mercury chloride and lead acetate promoted a significant decrease in acetylcholinesterase activity whereas they did not alter the gene expression pattern. In addition, the antioxidant competence was decreased after exposure to mercury chloride. The data presented here allowed us to hypothesize a signal transmission impairment, through alterations in cholinergic transmission, and also in the antioxidant competence of zebrafish brain tissue as some of the several effects elicited by these pollutants.

Radioprotective potential of a novel therapeutic formulation of oligoelements Se, Zn, Mn plus Lachesis muta venom.

In this study we evaluated in vivo the tolerance induced by the combination of Se, Zn and Mn (4 microg/ml each) plus Lachesis muta venom (4 ng/ml) (O-LM) to high doses of ionizing radiation. The protective effect of O-LM was investigated on the small-intestine and bone marrow of mice irradiated with a single whole-body dose of 10 Gy employing a (137)Cs source. Mice were sacrificed 3 days after irradiation. Mice receiving a subcutaneous daily O-LM injection starting 30 days before irradiation, showed a higher number of crypts, enhanced villous conservation and lack of edema or vascular damage in comparison to the untreated and irradiated group. In addition, O-LM treatment decreased vascular damage and the grade of aplasia preserving medullar progenies induced by ionizing radiation on mouse bone marrow. The protective effect of O-LM against radiation injury to the small intestine was associated with an increase in proliferation and a reduction of apoptosis in intestinal crypts and furthermore, to an enhanced intestinal immunoreactivity of MnSOD, and CuZnSOD, and also catalase. Based on the present results and taking into account that O-LM is being safely administered in phase I clinical trial as an immunomodulator, we suggest that O-LM could be an attractive candidate as a safe radioprotective agent for patients undergoing radiotherapy.

Alterations of valve closing behavior in juvenile Catarina scallops (Argopecten ventricosus Sowerby, 1842) exposed to toxic metals.

We conducted an evaluation of alterations produced in the valve closing speed of juvenile Argopecten ventricosus (Catarina scallop) exposed to the metals cadmium, chromium and lead, because of the connection of this response to the state of health of the mollusk. Bioassays were conducted with 50 juveniles (length 3 +/- 0.5 cm) exposed to 0.02, 0.1, 0.2 mg Cd l(-1); 0.1, 0.5, 1.0 mg Cr l(-1); 0.04, 0.2, 0.4 mg Pb l(-1) and 0.8 and 1.6 mg Cd + Cr + Pb l(-1) for 480 h. The average valve closing speed at the end of the experiment was under 1 s in the control group, from 2 to 3.6 s in the bioassays with cadmium, from 1.4 to 3.4 s with chromium, from 3 to 12 s with lead, and from 12 to 15 s with the metal mixtures. It was found that there are significant differences between the values recorded in assays with metals and the control (P < 0.05). The retardation of valve closing in the organisms exposed to toxic substances is probably caused by damage to the sensory cilia located on the edge of the mantle.

Occurrence of heavy metals and antibiotic resistance in bacteria from internal organs of american bullfrog (Rana catesbeiana) raised in Malaysia

A total of 40 bacteria have been successfully isolated from internal organs of the American bullfrog (Rana catesbeiana) raised in Malaysia, namely, eight isolates of Aeromonas spp., 21 of Edwardsiella spp., six of Flavobacterium spp. and five of Vibrio spp. In terms of antibiotic susceptibility testing, each isolate was tested against 21 antibiotics, resulting in 482 (57.3 percent) cases of sensitivity and 61 (7.3 percent) cases of partial sensitivity. Meanwhile, 297 (35.4 percent) bacterial isolates were registered as resistant. The multiple antibiotic resistance (MAR) index of each bacterial species indicated that bacteria from raised bullfrogs have been exposed to tested antibiotics with results ranging from 0.27 to 0.39. Additionally, high percentages of heavy metal resistance among these isolates were observed, with values ranging from 85.0 to 100.0 percent. The current results provided us information on bacterial levels of locally farmed bullfrogs exposed to copper, cadmium, chromium as well as 21 types of antibiotics.(AU)

Content and daily intake of copper, zinc, lead, cadmium, and mercury from dietary supplements in Mexico.

This study investigates the presence of Cu, Zn, Cd, Pb, and Hg in 24 dietary supplements purchased in different health stores across the city of Hermosillo, located in the northwest of Mexico. Analysis of metals was done by microwave digestion and atomic absorption spectroscopy. The most abundant elements in dietary supplements were Cu (<0.19-137.85 microg/g) and Zn (<2.83-4785.71 microg/g), followed by Pb (<0.003-66.32 microg/g), Cd (<0.001-2.90 microg/g), and Hg (<0.24-0.85 microg/g). The estimated daily intakes of metals were below those recommended by WHO and the Institute of Medicine, showing that little risk from heavy metals is associated with the consumption of the dietary supplements analyzed. However, some products presented more than 10% of the tolerable daily intake of Pb, indicating that production processes should be improved.

Estimate of toxic element intake in diets of pre-school children and elderly collected by duplicate portion sampling.

A study was carried out with a group of pre-school children staying at the central nursery of the University of São Paulo and with a group of elderly living in private institutions in São Paulo, Brazil, with the aim of evaluating the contents of toxic elements present in the diets of these groups. For sampling, the duplicate portion technique was used, which consisted of collecting all the foods and beverages consumed during three consecutive days. A radiochemical separation procedure was developed and applied to the determination of As, Cd, Sb, W, Th and U, by means of retention of these elements in the resin Chelex 100 and inorganic exchanger tin dioxide in an appropriate medium. The elements analysed presented levels of ingestion below the maximum levels recommended by the World Health Organization (WHO), and thus can be considered as not presenting any health hazard to the individuals studied in the present work.

Sorotipos de Salmonella de efluente de esgoto: níveis de resistência a metais pesados e transferência de marcadores / Salmonella serotypes from effluent sewage waters: levels of resistance to heavy metals, and markers transfer

A total of 278 Salmonella strains resistant to the heavy metals Cu, Hg and Zn were analyzed.The strains included the following four serotypes which were prevalent in isolates from the effluents of two sewage treatment plants in the city of Rio de Janeiro, RJ, from Brazil, 1984 to 1985: S.panama(118), S.typhimurium(58), S.agona(53) and S.oranienburg(49).Confirmation of the resistance patterns using a resistogram indicated in vitro stability for 96.7 por cento of the sample, including the Cu and Hg markers and excluding Zn.Up to 68.7 por cento of the strains were resistant to 200 ug/ml Cu and 77.7 por cento were resistant to 45ug/ml Hg.These frequencies were obtained by submitting the Salmonella strains to increasing concentrations of Cu(100 to 250ug/ml) and Hg(5 to 50 ug/ml)incorporated into nutrient agar. For a total of 268 conjugation experiments, in which the standard Escherichia coli K 12 F-Na1 strain and cultures isolated from sewage water (Citrobacter freundii Tc and Salmonella oranienburg Sm ) were considered to be the recipients, Cu transconjugants were isolated at an overall rate of 19.3 por cento and Hg transcomjugant at a rate of 86.4 por cento.All of the transconjugant analyzed expressed the same level of resistance as the corresponding Salmonella(donor)strain.We discuss the significance of these results in terms of the dissemination of genetic markers in view of the continued discharge of sewage effluent contaning these microorganisms into the Bay of Guanabara