Total Mercury and Selenium in wild Shrimp from Coastal Lagoons of Northwest Mexico: Human Health risk Assessment.

This study analyzed total mercury (THg), and selenium (Se) in edible tissues of white shrimp (Litopenaeus vannamei), blue shrimp (L. stylirostris) and brown shrimp (F. californiensis), from three states of the Northwest of Mexico in September and October 2017. Concentrations of THg and Se in the muscle were between 0.026 and 0.829 and 0.126-1.741 µg/g dry weight (dw), respectively. Significant differences were observed among Hg concentration of Sonora and Nayarit and among Se concentration of Sinaloa and Nayarit. In addition, the health risk assessment (HQ) in the three species of shrimp was between 0.550 and 0.607. All Se:Hg molar ratios were > 1 and positive HBVSe values that showed that shrimp from Northwest of Mexico does not represent a risk to human health.

Selenium dietary intake, urinary excretion, and toxicity symptoms among children from a coal mining area in Brazil.

Selenium (Se) is necessary for several physiological functions in the human body; however, high concentrations of this element in coal mining areas raise the possibility of Se-related health risks. Children are much more vulnerable and at risk to environmental hazards than adults. The largest coal mining area of Brazil is located in the city of Candiota, where previous studies point to significant urinary Se concentrations among children. Food intake is the main Se source. The study aimed to evaluate dietary Se intake, as well as urinary Se excretion and classic symptoms of Se intoxication among children from Candiota and a control city in the same region. A cross-sectional study was carried out, with participation from 242 children between 6 and 12 years old in two cities in Rio Grande do Sul state, Brazil. Socioeconomic variables, dietary intake, and Se toxicity symptoms were evaluated through a structured questionnaire, and urinary Se levels were measured. Children from both cities had normal levels of Se intake and urinary excretion; however, children from Candiota had significantly higher levels of Se in both parameters in relation to the control city, especially for Se urinary excretion. There was low prevalence of Se toxicity symptoms. We conclude that coal mining activities may increase Se intake in children and consequently its urinary excretion.

Metamorphic acceleration following the exposure to lithium and selenium on American bullfrog tadpoles (Lithobates catesbeianus).

To regulate the presence of contaminants in Brazilian water, the Brazilian Environmental Council (CONAMA) promulgates regulations regarding the concentrations of given compounds that are supposed to be safe for aquatic life. Considering these regulations, this study tested the effects of considered safe levels of lithium (2.5 mgL-1) and selenium (0.01 mgL-1), isolated and mixed, on the American bullfrog (Lithobates catesbeianus) tadpoles. The evaluation was done through the use of biomarkers of larval development as total wet weight (TWW), snout-vent-length (SVL), hind-limb-length (HLL), activity level (AL), histologic evaluation of the thyroid gland and the mortality rate. The tadpoles were allocated into four groups (n = 20 each): a control group (CT); a group exposed to lithium (LI), a group exposed to selenium (SE), and a group exposed to both lithium and selenium (SELI). The whole assay was carried out over 21 days, with two rounds of data collection (on 7th and 21st day) to evaluate the responses over time. A statistical reduction in the AL was observed in the tadpoles from the LI and SELI groups after 7 days of exposure, the same pattern was observed after 21 days. Histological analyses of the thyroid gland showed signs of up-regulation (i.e. statistic reduction in number and area of the follicles, as well a significant reduction in the area of the gland) in all exposed groups, which represents an endocrine response as an adaptative strategy to deal with polluted aquatic environment. The stress triggered by the polluted medium is discussed.

Metabolic, immunologic, and histopathologic responses on premetamorphic American bullfrog (Lithobates catesbeianus) following exposure to lithium and selenium.

The presence of chemicals and the destruction of freshwater habitats have been addressed as one of the reasons for the decline in the amphibians' populations worldwide. Considering the threat that these animals have been suffering in tropical regions, the present study tested if the Brazilian legislation, concerning the permissive levels of lithium and selenium in water bodies and effluents, warrants the protection of aquatic life. To do so, we assessed the metabolic, immunologic, and histopathologic alterations in liver samples of American bullfrog (Lithobates catesbeianus), at the premetamorphic stage, through biomarkers indicative of general energetic status, i.e., glucose, lipid, and protein metabolism using biochemical and histochemical approaches. The immunologic responses were assessed by the quantification of melanomacrophage centres (MMCs); the histopathologic evaluation of the liver sections was also performed. The assay was carried out over 21 days with two periods of sampling (after 7 and 21 days) to assess the effects of exposure over time. The animals were exposed to the considered safe levels of lithium (2.5 mg L-1) and selenium (10 µg L-1), both, isolated and mixed. The exposed animals showed alterations in glucose and lipid metabolism throughout the experiment. The intense presence of MMCs and histopathological responses are compatible with hepatotoxicity. The toxicity expressed by the employed animal model indicates that the Brazilian environmental legislation for the protection of aquatic life needs to be updated. With this study, we intend to provide data for better environmental policies and bring attention to sublethal effects triggered by the presence of contaminants in the aquatic environment.

Selenium toxicity stress-induced phenotypical, biochemical and physiological responses in rice plants: Characterization of symptoms and plant metabolic adjustment.

Selenium (Se) at low concentration is considered benefit element to plants. The range between optimal and toxic concentration of Se is narrow and varies among plant species. This study aimed to evaluate the phenotypic, physiological and biochemical responses of four rice genotypes (BRS Esmeralda, BRSMG Relâmpago, BRS Bonança and Bico Ganga) grown hydroponically treated with sodium selenate (1.5 mM L-1). Selenium treated plants showed a dramatically decrease of soluble proteins, chlorophylls, and carotenoids concentration, resulting in the visual symptoms of toxicity characterized as leaf chlorosis and necrosis. Selenium toxicity caused a decrease on shoot and root dry weight of rice plants. Excess Se increased the oxidative stress monitored by the levels of hydrogen peroxide and lipid peroxidation. The enzymatic antioxidant system (catalase, superoxide dismutase, and ascorbate peroxidase) increased in response to Se supply. Interestingly, primary metabolism compounds such as sucrose, total sugars, nitrate, ammonia and amino acids increased in Se-treated plants. The increase in these metabolites may indicate a defense mechanism for the osmotic readjustment of rice plants to mitigate the toxicity caused by Se. However, these metabolites were not effective to minimize the damages on phenotypic traits such as leaf chlorosis and reduced shoot and root dry weight in response to excess Se. Increased sugars profile combined with antioxidant enzymes activities can be an effective biomarkers to indicate stress induced by Se in rice plants. This study shows the physiological attributes that must be taken into account for success in the sustainable cultivation of rice in environments containing excess Se.

Commentary: Health Concerns of Brazil Nut Consumption.

Brazil nuts are the fruit of the enormous tropical tree Bertholletia excelsa that are produced in and exported from the territory of the Amazon. As a natural rich source of selenium (Se), the consumption of Brazil nuts is often suggested as therapeutic among patients with autoimmune thyroid diseases. In this review, the current knowledge regarding the main health concerns of Brazil nut consumption, such as Se toxicity, Se-induced type 2 diabetes mellitus, weight gain, radioactivity, aflatoxins, and allergic reactions, is presented and discussed.

Impact of selenium on mortality, bioaccumulation and feeding deterrence in the invasive Argentine ant, Linepithema humile (Hymenoptera: Formicidae).

Ants are known for the important roles they play in processes contributing to ecosystem functioning in many habitats. However, pollutants can impact the ecosystem services provided by ants. The Argentine ant, an invasive species in North America, was investigated for the potential impact selenium (Se) may have on ants residing within a contaminated habitat. Mortality tests were conducted using worker ants fed an artificial nectar source containing 1-of-4 environmentally common Se compounds (forms): seleno-l-methionine, methylselenocysteine, selenate or selenite. Accumulation of Se in ant bodies at the end of two weeks was quantified with the use of hydride generation atomic absorption spectroscopy. Lastly, we conducted choice tests using dyes to determine whether ants might avoid a carbohydrate diet containing Se by providing them a choice between sucrose with or without Se. Choice tests also tested the responses of ants to selenium when provided in different background sucrose concentrations. The results of this study indicated that form and quantity of Se, as well as time of exposure, impact mortality in Argentine ant workers. Methylselenocysteine and selenate were found to be the most toxic among the 4 chemical forms when presented in sucrose solutions, whereas seleno-l-methionine and selenite caused greater Se body burdens. Furthermore, choice tests showed that ants did not prefer control sucrose solution to sucrose treated with Se regardless of the background sucrose concentration. These findings serve as first look into the possible detrimental impacts these contaminants may pose for ants that frequent sugary nectar sources.

Effects of oligoelements Se, Zn, and Mn plus Lachesis muta venom in experimental scleroderma.

Scleroderma, sclerosis of the skin, is a severe autoimmune disease refractant to all kind of treatments. To study the in vivo effects of a combination of three oligoelements selenium (Se), zinc (Zn), and manganese (Mn) plus Lachesis muta venom (O-LM) on the bleomycin (BLM)-induced scleroderma mouse experimental model. C3H mice were randomly divided into four groups: control (phosphate-buffered saline (PBS)), O-LM, BLM, and BLM + O-LM. All administrations were performed subcutaneously into the back of mice. BLM was injected 5 days per week for three consecutive weeks and O-LM was administered simultaneously with BLM from the beginning of the experiments and lasted for 3 weeks after the final BLM or PBS injection (for O-LM and BLM + O-LM groups), when animals were sacrificed and histopathological, immunohistochemical, thiobarbituric acid reactive species (TBARS) evaluation, and autoantibodies detection were determined. O-LM significantly reduced BLM-induced enhanced dermal thickness (605 ± 47 vs. 956 ± 59 µm, P < 0.01), collagen deposition, and mast cells infiltration (43.1 ± 1.0 vs. 102 ± 14.1 mast cells, P < 0.05). O-LM administration significantly blocked BLM-induced oxidative damage and the enhanced immunoreactive fibroblasts for α-smooth muscle actin while reduced BLM-induced autoantibodies that strongly react mainly with skin and spleen. O-LM significantly reduced BLM-induced scleroderma through the modulation of antioxidant and immunological pathways.

Assessment of trace elements and stable isotopes of three Ardeid species at Birama Swamp, Cuba.

The Birama Swamp is the second largest wetland in the Caribbean region and it is inhabited by large populations of waterbirds. Here we report, for the first time, the foraging ecology and pollutant levels of three Ardeidae species: Cattle egret (Bubulcus ibis), Snowy egret (Egretta thula), and Tricolored heron (E. tricolor) breeding in this wetland using stable-isotope (δ (15)N and δ (13)C) and trace elements [mercury (Hg), lead (Pb), and selenium (Se)] analysis of chick feathers. Our results showed that individuals from all species occupied similar trophic levels. However, we found significant differences for δ (13)C, with the highest values in cattle egret indicating its use of terrestrial habitats and a generalist and opportunist behavior. No significant differences were found for Pb among species. Yet, Hg levels were greater and similar in tricolored heron and snowy egret than in cattle egret, which was associated with their greater use of aquatic environments. Snowy egret had the lowest values of Se differing significantly with the other two species suggesting a different relative use of prey type. Modeling log-Hg concentration in relation to δ (15)N and δ (13)C showed an independent and significant relationship among species but without interaction with species level indicating that within a particular species, higher Hg levels were associated with higher δ (15)N values. There was no interaction between δ (15)N and δ (13)C in the general linear models for Se and Pb in all species. We found an association between δ (15)N and species in Pb for snowy egret. The foraging habitat use of these species and the low levels of pollutants, which are lower than in other similar habitats in other areas of the world, indicated that there is not risk of negative effects in juvenile birds of the Birama Swamp colony that may impair their survival. Our results can be used as a baseline to achieve management regulations.

Toxicology and pharmacology of selenium: emphasis on synthetic organoselenium compounds.

The advance in the area of synthesis and reactivity of organoselenium, as well as the discovery that selenium was the cause of severe intoxication episodes of livestock in the 1930s and the subsequent determination that selenium was an essential trace element in the diet for mammals, has motivated intense studies of the biological properties of both organic and inorganic selenium compounds. In this review, we shall cover a wide range of toxicological and pharmacological effects, in which organoselenium compounds are involved but the effects of inorganic compounds were not discussed in detail here. The molecular toxicity of inorganic selenium was described in relation to its interaction with endogenous -SH groups to allow a comparison with that of synthetic organoselenium compounds. Furthermore, in view of the recent points of epidemiological evidence that overexposure to selenium can facilitate the appearance of chronic degenerative diseases, we also briefly revised the history of selenium toxicity and physiology and how environmental selenium can reach inside the mammalian cells. The biological narrative of the element selenium, in the last century, has been marked by a contrast between its toxic and its beneficial effects. Thus, the potential therapeutic use of simple organoselenium compounds has not yet been sufficiently explored and, consequently, we cannot discard this class of compounds as promising pharmaceutical agents. In effect, the future of the organochalcogens as pharmacological agents will depend on more detailed toxicological studies in the oncoming years.

[Selenium supplementation in critically ill patients: pharmacological issues and current evidence]. / Suplementación con selenio en el paciente crítico: aspectos farmacológicos y evidencia actual.

High dose intravenous selenium may be associated with a significant reduction in mortality among critically ill patients with systemic inflammation. Currently, parenteral selenium as sodium selenite seems to be a cornerstone of the antioxidant defence in the critically ill. So far, several clinical trials have evaluated the effects of selenium in monotherapy or as part of a multi-micronutrient approach, on relevant clinical end points for critically ill patients. Nonetheless, the results from these studies have sometimes been contradictory. We now have a better understanding of the pharmacokinetics of the initial and transient pro-oxidant effect of an intravenous bolus followed by the antioxidant effect of continuous infusion, which seems efficacious and safe among critically ill patients. Clinical confirmation of the potentially advantageous synergism between selenium and glutamine may soon be forthcoming but the most appropriate and the optimum time of supplementation remains undetermined. Short-term intravenous selenite (bolus injection plus continuous infusion) has shown to be safe and capable of optimizing serum selenium and antioxidant selenoenzymes activities. However, additional dose-ranging trials are necessary to elucidate an optimal and safe posology with confirmed pharmacokinetic profiles before more definitive phase III trials can be conducted.

Levels of As, Cd, Pb, Cu, Se and Zn in bovine kidneys and livers in Jamaica.

Paired liver and kidney samples from 100 free-range cattle in different parts of Jamaica were analyzed for essential and non-essential trace elements. We found significant enrichment of elements in the kidney (K) compared to the liver (L) with the K/L concentration ratios being 5.2 for Cd, 4.1 for Pb, 3.5 for Se and 2.1 for As, but the Cu contents of the kidney were significantly higher with the K/L ratio of 0.45. A large number of kidney and liver samples showed Cu concentrations in the ranges that were associated with deficiency effects in mammals. About 15% of the hepatic samples had Zn concentrations below 20 microg/g, suggesting that there might be zinc insufficiency in some of the animals. Positive associations were found between the metals in both the kidney and liver. On average, the intake of Cd from consumption of both bovine kidney and liver from the island was estimated to be 5.2 microg/day, equivalent to about 7% of the provisional tolerable daily intake (PTDI), although anyone who habitually consumed the few kidneys or livers with >40 microg/g cadmium may be at some risk of exceeding the PTDI. The consumption of offal from local animals did not appear to be an important dietary source of any of the essential microelements.

Selenio y salud animal Importancia, deficiencia, suplementación y toxicidad / Selenium and animal health: importance, defficiency, supplementation and toxicity / Selênio e saúde animal importância, deficiência, suplementação e toxidez

El selenio (Se) es un mineral esencial en la nutrición animal y se considera su participación en diversos procesos asociados a la producción animal, tan diversos como la fertilidad de la especie y la prevención de enfermedades. Laglutatión-peroxidasa (GSH-Px), fue la primera enzima en que se demostró la presencia activa del selenio y su importancia al evitar el daño oxidativo de las membranas celulares. Con anterioridad se había demostrado que la conocida como “Enfermedad del músculo blanco” era consecuencia de la deficiencia de Se, determinando muerte en animales recién nacidos y ocasionalmente en animales en desarrollo y aún en adultos, en particular en rumiantes. Actualmente ha quedado claro que el Se también es crítico en la estructuración de las enzimas necesarias para la síntesis de la hormona tiroidea y para su activaciónen los tejidos periféricos, pasando de T4 a T3. La deficiencia de Se afecta seriamente la capacidad de respuesta inmune de los animales. El diagnóstico de la deficiencia debe fundamentarse en los niveles del elemento en los suelos, las plantas forrajeras y la condición del animal en sangre y tejidos. Se han instrumentado diversas formas de suplementación del elemento que pueden emplearse dependiendo de las condiciones productivas de los animales y sus niveles previos de Se. La intoxicación por Se (Selenosis) debe tenerse en cuenta en los programas de suplementación, y puede ocurrir en formas crónicas o agudas. Las formas crónicas ocurren en regiones con suelos ricos en el elemento y condiciones que favorecen su absorción por las plantas forrajeras. Las formas agudas generalmente ocurren por excesos del elemento en las dietas o las sales que se administran a los animales o por errores de dosificación en las formulaciones parenterales. La relación metabólica del Se entre la hembra gestante, el feto y el recién nacido, es un área que requiere mayor investigación.

O selênio (Se) é um mineral essencial na nutrição animal e se considera sua participação em diversos processos associados à produção animal, tão diversos como na fertilidade das espécies e prevenção de enfermidades. A glutation peroxidase (GSH-Px), foi a primeira enzima em que se demonstrou a presença ativa do selênio e sua importância para evitar o dano oxidativo nas membranas celulares. Anteriormente sabia-se que a “enfermidade do músculo branco” era conseqüência da deficiência de Se, determinando a morte em animais recém-nascidos e ocasionalmente em animais em desenvolvimento, animais adultos e em particular em ruminantes. Atualmente, está claro que o Se é crítico na estruturação das enzimas necessáriaspara a síntese de hormônios da tireóide e para sua ativação nos tecidos periféricos, passando de T3 a T4. A deficiência de Se afeta seriamente a capacidade da resposta imune dos animais. O diagnóstico da deficiência deve fundamentar-se nos níveis deste elemento no solo, nas plantas forrageiras e nas condições do animal. Indicam-se diversas formas de suplementação deste elemento, que podem ser empregadas dependendo das condições produtivas dos animais e seus níveis prévios de Se. As intoxicações por Se (selenose), devem ser consideradas nos programas de suplementação, que pode ocorrer de forma crônica ou aguda. As formas crônicas ocorrem em regiões com solos ricos no elemento e nas condições que favorecem a absorção pelas plantas forrageiras. As formas agudas geralmente ocorrem por excesso do elemento nas dietas, ou sais administrados aos animais ou por erros na dosagem das formulações parenterais. A relação metabólica do Se na fêmea gestante, o feto e orecém-nascido, é uma área que requer uma maior investigação.

Selenium (Se) is an essential trace element for animal nutrition and plays multiple actions related to animal production, fertility and prevention of diseases. Glutathione peroxidase enzyme (GSH-Px) was the first seleno enzyme to demonstrate the active presence of selenium and its importance to prevent cellular membrane oxidative damage. Formerly, White muscle disease (WMD) was recognized as resulting from Se deficiency, determining new born mortality and adult animals, especially in ruminants. Nowadays, it is clear that Se is critical for thyroid hormone synthesis and its activation in peripheral tissues – from T3 to T4. Lack of Se seriously affects the capacity of immune response by the animals. Se status in the soil, plants, animal blood and tissues can be used as a tool to diagnose Se deficiency. Several forms of Se supplementation are described which can be applied depending of the productive capacity of the animals and their previous levels of Se. Acute and chronic Se intoxication (Selenosis) should be considered in supplementation programs as it may occur in a chronic or acute way. Chronic forms are associated to regional seleniferous soils, with permanent or repeated consumption of seleniferous plants. Acute forms are associated with high ingestion of Se as a result of wrongly designed diets, salt provided to the animals or parenteral injection dosage mistakes. The metabolic relation among Se, the fetus, the newborn and the pregnant dam requires further investigations.

Over-activation of the Drosophila melanogaster hsp83 gene by selenium intoxication

Selenium is an important dietary micronutrient and an essential component of selenoproteins and the active sites of some enzymes, although at high concentrations it is toxic. We investigated diphenyl diselenide ((C6H5)2Se2 ) for its effects on the developmental stages of Drosophila melanogaster and found that in the larval and pupae stages the toxic threshold for this compound when added to the banana-agar medium on which the larva were fed was 350 µmol. In adult flies, fed on the same media, there were no observable toxic effects below 500 µmol but there were toxic effects above 600 µmol, indicating that adult flies were more resistant to selenium intoxication. In larvae, a when diphenyl diselenide was present above the toxic threshold there was increased activation of the hsp83 heat shock protein gene. Selenium promotes oxidation of sulfhydryl groups and affects the folding of proteins and this could explain the over-expression of hsp83 because the product of this gene is involved in protein folding and defense responses, including the response to heat shock.

Selenio y salud animal Importancia, deficiencia, suplementación y toxicidad / Selênio e saúde animal importância, deficiência, suplementação e toxidez / Selenium and animal health: importance, defficiency, supplementation and toxicity

El selenio (Se) es un mineral esencial en la nutrición animal y se considera su participación en diversos procesos asociados a la producción animal, tan diversos como la fertilidad de la especie y la prevención de enfermedades. Laglutatión-peroxidasa (GSH-Px), fue la primera enzima en que se demostró la presencia activa del selenio y su importancia al evitar el daño oxidativo de las membranas celulares. Con anterioridad se había demostrado que la conocida como “Enfermedad del músculo blanco” era consecuencia de la deficiencia de Se, determinando muerte en animales recién nacidos y ocasionalmente en animales en desarrollo y aún en adultos, en particular en rumiantes. Actualmente ha quedado claro que el Se también es crítico en la estructuración de las enzimas necesarias para la síntesis de la hormona tiroidea y para su activaciónen los tejidos periféricos, pasando de T4 a T3. La deficiencia de Se afecta seriamente la capacidad de respuesta inmune de los animales. El diagnóstico de la deficiencia debe fundamentarse en los niveles del elemento en los suelos, las plantas forrajeras y la condición del animal en sangre y tejidos. Se han instrumentado diversas formas de suplementación del elemento que pueden emplearse dependiendo de las condiciones productivas de los animales y sus niveles previos de Se. La intoxicación por Se (Selenosis) debe tenerse en cuenta en los programas de suplementación, y puede ocurrir en formas crónicas o agudas. Las formas crónicas ocurren en regiones con suelos ricos en el elemento y condiciones que favorecen su absorción por las plantas forrajeras. Las formas agudas generalmente ocurren por excesos del elemento en las dietas o las sales que se administran a los animales o por errores de dosificación en las formulaciones parenterales. La relación metabólica del Se entre la hembra gestante, el feto y el recién nacido, es un área que requiere mayor investigación.(AU)

O selênio (Se) é um mineral essencial na nutrição animal e se considera sua participação em diversos processos associados à produção animal, tão diversos como na fertilidade das espécies e prevenção de enfermidades. A glutation peroxidase (GSH-Px), foi a primeira enzima em que se demonstrou a presença ativa do selênio e sua importância para evitar o dano oxidativo nas membranas celulares. Anteriormente sabia-se que a “enfermidade do músculo branco” era conseqüência da deficiência de Se, determinando a morte em animais recém-nascidos e ocasionalmente em animais em desenvolvimento, animais adultos e em particular em ruminantes. Atualmente, está claro que o Se é crítico na estruturação das enzimas necessáriaspara a síntese de hormônios da tireóide e para sua ativação nos tecidos periféricos, passando de T3 a T4. A deficiência de Se afeta seriamente a capacidade da resposta imune dos animais. O diagnóstico da deficiência deve fundamentar-se nos níveis deste elemento no solo, nas plantas forrageiras e nas condições do animal. Indicam-se diversas formas de suplementação deste elemento, que podem ser empregadas dependendo das condições produtivas dos animais e seus níveis prévios de Se. As intoxicações por Se (selenose), devem ser consideradas nos programas de suplementação, que pode ocorrer de forma crônica ou aguda. As formas crônicas ocorrem em regiões com solos ricos no elemento e nas condições que favorecem a absorção pelas plantas forrageiras. As formas agudas geralmente ocorrem por excesso do elemento nas dietas, ou sais administrados aos animais ou por erros na dosagem das formulações parenterais. A relação metabólica do Se na fêmea gestante, o feto e orecém-nascido, é uma área que requer uma maior investigação.(AU)

Selenium (Se) is an essential trace element for animal nutrition and plays multiple actions related to animal production, fertility and prevention of diseases. Glutathione peroxidase enzyme (GSH-Px) was the first seleno enzyme to demonstrate the active presence of selenium and its importance to prevent cellular membrane oxidative damage. Formerly, White muscle disease (WMD) was recognized as resulting from Se deficiency, determining new born mortality and adult animals, especially in ruminants. Nowadays, it is clear that Se is critical for thyroid hormone synthesis and its activation in peripheral tissues from T3 to T4. Lack of Se seriously affects the capacity of immune response by the animals. Se status in the soil, plants, animal blood and tissues can be used as a tool to diagnose Se deficiency. Several forms of Se supplementation are described which can be applied depending of the productive capacity of the animals and their previous levels of Se. Acute and chronic Se intoxication (Selenosis) should be considered in supplementation programs as it may occur in a chronic or acute way. Chronic forms are associated to regional seleniferous soils, with permanent or repeated consumption of seleniferous plants. Acute forms are associated with high ingestion of Se as a result of wrongly designed diets, salt provided to the animals or parenteral injection dosage mistakes. The metabolic relation among Se, the fetus, the newborn and the pregnant dam requires further investigations.(AU)

Selenium and aflatoxin levels in raw Brazil nuts from the Amazon basin.

Whereas selenium (Se) is an important antioxidant in human metabolism to prevent cancer, aflatoxins are highly carcinogenic. Brazil nuts from Eastern and Western Amazon regions were evaluated to find any relationship between Se and aflatoxins levels. A total of 80 (in-shell and shelled) nuts samples were collected directly from different forest sites and analyzed for Se by atomic emission spectrometry and aflatoxins by liquid chromatography tandem mass spectrometry. The limit of quantitation (LOQ) for Se was 2.0 mg/kg, and LOQ for total aflatoxins was 0.390 microg/kg. Nut Se levels from the Eastern region were higher than the Western, in addition to the aflatoxins. The moisture content (mc) and water activity (aw) of the raw nuts from the two regions did not present a significant difference, for either in-shell or shelled. The mc was 24.5% (minimum of 20.1% and maximum of 30.4%) and 22.1% (minimum of 14.6% and maximum of 28.9%) and a w of 0.85 for both regions. Further studies need to be carried out to discover the role of Se on fungi growth stress and aflatoxin production mechanisms.

Enfermidades associadas à intoxicação por selênio em animais / Diseases associated with selenium poisoning in animals

Por meio de revisão da literatura pertinente foram coligidos e são apresentados os principais dados relativos à intoxicação por selênio em animais domésticos. Foram abordados e discutidos os aspectos epidemiológicos, clínicos, anátomo e histopatológicos e patogenéticos atribuídos a Alkali Disease, Blind Staggers, intoxicação aguda e poliomielomalácia simétrica focal dos suínos. O trabalho tem como objetivo esclarecer pontos obscuros relativos à intoxicação por selênio, bem como alertar para os riscos que a suplementação com esse elemento pode representar.

Trough a critical literature review, the main data of selenium poisoning in domestic animals are presented. Epidemiological, clinical, anatomic and histopathological aspects attributed to Alkali Disease, Blind Staggers, acute poisoning and focal symmetrical poliomielomalacia of swine are discussed. The main objective of the paper is to clarify obscure points of selenium poisoning, as well to point out the risks that supplementation with this element can represent.

Enfermidades associadas à intoxicação por selênio em animais / Diseases associated with selenium poisoning in animals

Por meio de revisão da literatura pertinente foram coligidos e são apresentados os principais dados relativos à intoxicação por selênio em animais domésticos. Foram abordados e discutidos os aspectos epidemiológicos, clínicos, anátomo e histopatológicos e patogenéticos atribuídos a Alkali Disease, Blind Staggers, intoxicação aguda e poliomielomalácia simétrica focal dos suínos. O trabalho tem como objetivo esclarecer pontos obscuros relativos à intoxicação por selênio, bem como alertar para os riscos que a suplementação com esse elemento pode representar.(AU)

Trough a critical literature review, the main data of selenium poisoning in domestic animals are presented. Epidemiological, clinical, anatomic and histopathological aspects attributed to Alkali Disease, Blind Staggers, acute poisoning and focal symmetrical poliomielomalacia of swine are discussed. The main objective of the paper is to clarify obscure points of selenium poisoning, as well to point out the risks that supplementation with this element can represent.(AU)

Differences in SEM-AVS and ERM-ERL predictions of sediment impacts from metals in two US Virgin Islands marinas.

Two US Virgin Islands marinas were examined for potential metal impacts by comparing sediment chemistry data with two sediment quality guideline (SQG) values: the ratio of simultaneously extractable metals to acid volatile sulfides (SEM-AVS), and effects range-low and -mean (ERL-ERM) values. ERL-ERMs predicted the marina/boatyard complex (IBY: 2118 microg/g dry weight total metals, two exceeded ERMs) would have greater impacts than the marina with no boatyard (CBM: 231 microg/g dry weight total metals, no ERMs exceeded). The AVS-SEM method predicted IBY would have fewer effects due to high AVS-forming metal sulfide complexes, reducing trace metal bioavailability. These contradictory predictions demonstrate the importance of validating the results of either of these methods with other toxicity measures before making any management or regulatory decisions regarding boating and marina impacts. This is especially important in non-temperate areas where sediment quality guidelines have not been validated.