Selenium

About: Selenium is a research topic. Over the lifetime, 21192 publications have been published within this topic receiving 429715 citations. The topic is also known as: Se & selen.

Determination of dissolved selenium species in environmental water samples using isotope dilution mass spectrometry

Abstract: In order to clarify the species composition of selenium in environmental water samples, analytical methods have been developed for the selective determination of different chemical forms of this element (selenite, selenate, and organic species including trimethylselenonium) using isotope dilution mass spectrometry (IDMS). The species analysis was made possible by means of chromatographic separation procedures and an 82Se-enriched selenate, selenite, and trimethylselenonium spike for the isotope dilution process. The total selenium concentration was determined after decomposition of organic compounds with a HNO3/HCIO4 mixture. Selenium was measured in the mass spectrometer by producing negative Se- thermal ions for detection. Precise determination at the parts-per-trillion level was achieved. This new methodology was applied to different types of natural water samples (groundwater, pond water, river water, moorland lake water) with total selenium concentrations in the range of 200 pg/g to 15 ng/g. Selenite and selenate have been the only detected species in most of the investigated samples, with selenate dominating all except one. In samples with high contents of dissolved organic carbon, however, different organoselenium compounds including trimethylselenonium ions were additionally quantified in the range of 10-95 pg/g. In these cases, the sum of all selenium species agreed well with the independently determined total element concentration.

The controversy surrounding selenium and cardiovascular disease: a review of the evidence.

Abstract: Selenium is an essential trace element that is an integral part of many proteins, with catalytic and structural functions. The antioxidant properties of some selenoproteins, such as glutathione peroxidase, may be particularly important in carcinogenesis and heart disease. The content of selenium in food depends on the selenium content of the soil where the plants are grown or the animals are raised. Moreover, the metabolism of selenium is determined by its dietary form: some forms are better utilized than others. Therefore, wide variations have been found in selenium status in different parts of the world. In animal studies, selenium deficiency is associated with cardiomyopathy and sudden death, as well as reduced T-cell counts and impaired lymphocyte proliferation and responsiveness. Abnormalities in liver function, brain, heart, striated muscle, pancreas and genital tract have also been reported. In humans, selenium deficiency has been implicated in the etiology of cardiovascular disease and other conditions in which oxidative stress and inflammation are prominent features, but there is still only limited evidence from epidemiological and ecological studies for this, and the therapeutic benefit of selenium administration in the prevention and treatment of cardiovascular diseases remains insufficiently documented. Interventions studies are currently in progress to assess the benefits of selenium supplements in primary and secondary prevention of atherosclerosis. The results to date are inconclusive and further controlled trials are needed.

Antagonistic Interaction of Mercury and Selenium in a Marine Fish Is Dependent on Their Chemical Species

Abstract: It is well-known that selenium (Se) shows protective effects against mercury (Hg) bioaccumulation and toxicity, but the underlying effects of Se chemical species, concentration, and administration method are poorly known. In this study, we conducted laboratory studies on a marine fish Terapon jurbua to explain why Hg accumulation is reduced in the presence of Se observed in field studies. When Se and Hg were administrated concurrently in the fish diets, different Se species including selenite, selenate, seleno-dl-cystine (SeCys), and seleno-dl-methionine (SeMet) affected Hg bioaccumulation differently. At high concentration in fish diet (20 μg g−1 normally), selenate and SeCys significantly reduced the dietary Hg(II) assimilation efficiency (AE) from 38% to 26%. After the fish were pre-exposed to dietary selenite or SeMet (7 μg g−1 normally) for 22 days with significantly elevated Se body concentrations, the Hg(II) AEs were pronouncedly reduced (from 41% to 15−26%), whereas the dissolved uptake rate const...

Determination of Selenium Species in Environmental Samples

Abstract: The essential nature of selenium as well as its toxicity depend on the concentration and the chemical forms in which this element is present in a given sample. Dissolved inorganic selenium can be found in natural water and soil as selenides, selenite and selenate. Organoselenium compounds present in air, soil and plants are volatile methylselenides, trimethylselenonium ion and several selenoamino acids. This review is a summary of recent research on the determination of selenium species in environmental samples such as water, air, soil and plants. Stability of selenium species in solutions and their storage is also discussed. In the metabolic pathway in the body selenide could act as the common intermediate for inorganic and organic Se sources as well as the checkpoint between further utilisation and excretion of selenium.

Selenium, iron, copper, and zinc levels and copper-to-zinc ratios in serum of patients at different stages of viral hepatic diseases.

Abstract: Viral hepatic diseases, especially those induced by the hepatitis B virus, can progress into more serious pathological outcomes and eventually to hepatocellular carcinoma. A growing body of evidence indicates that many trace elements play important roles in a number of carcinogenic processes that proceed through various mechanisms. To examine the status of trace elements during the development of hepatic carcinoma, we determined the selenium, iron, copper, and zinc levels and copper-to-zinc ratios in the serum of patients at different stages of viral hepatic disease. We observed significant changes in the selenium, iron, copper, and zinc levels in the serum of patients having hepatocellular carcinoma, relative to those of healthy controls (p < 0.05). The mean serum copper level in patients with hepatocellular carcinoma was significantly higher than that of the control group. In contrast, the mean selenium, iron, and zinc levels in patients having hepatocellular carcinoma were significantly lower than those of the control group. In addition, the mean zinc level in the serum of patients with hepatic cirrhosis was significantly lower than that of the control group (p < 0.05). Moreover, we found markedly elevated Cu: Zn ratios (p < 0.05) in patients having hepatic cirrhosis or hepatocellular carcinoma. Our findings imply that the levels of some trace elements, such as selenium, iron, copper, and zinc, and Cu: Zn ratios, might serve as biomarkers for the increased severity of viral hepatic damage.