Search results for "selenium"

Determination of toxic elements by cathodic-stripping-voltammetry

1981

The DPCSV determination of arsenic, selenium and tellurium in the sub-ng/ml range is discussed. After electrolytic deposition of the elements as intermetallic compounds with copper on the electrode surface, the determination is carried out by cathodic stripping. The simultaneous determination of selenium and tellurium or of selenium and arsenic is possible. Problems which occur in the application of these methods are discussed.

Conformations and Energetics of Sulfur and Selenium Diimides

2003

The geometries and energetics of different conformations of sulfur and selenium diimides E(NR) 2 (E = S, Se; R = H, Me, 'Bu, C 6 H 3 Me 2 -2,6, SiMe 3 ) have been studied by using various ab initio and DFT molecular orbital techniques. The syn,syn conformation is found to be most stable for parent E(NH) 2 , but in general, the preferred molecular conformation for substituted chalcogen diimides is syn,anti. In the case of E(NH) 2 the present calculations further confirm that syn,syn and syn,anti conformations lie energetically close to each other. From the three different theoretical methods used, B3PW91/6.31G * proved to be the most suitable method for predicting the geometries of chalcogen…

Prooxidative toxicity and selenoprotein suppression by cerivastatin in muscle cells

2012

Statins are the most widely used drugs for the treatment of hypercholesterolemia. In spite of their overall favorable safety profile, they do possess serious myotoxic potential, whose molecular origin has remained equivocal. Here, we demonstrate in cultivated myoblasts and skeletal muscle cells that cerivastatin at nanomolar concentrations interferes with selenoprotein synthesis and evokes a heightened vulnerability of the cells toward oxidative stressors. A correspondingly increased vulnerability was found with atorvastatin, albeit at higher concentrations than with cerivastatin. In selenium-saturated cells, cerivastatin caused a largely indiscriminate suppression of selenoprotein biosynth…

Role of endoscopic ultrasonography in the evaluation of high risk pancreatic cystic lesions: Ten year single center experience

2012

s / Pancreatology 12 (2012) 502–597 530 selenium content in second group was increased up to 96,5 3,29 mg/l (p <0,001). Conclusions: SS is an effective drug in treatment of selenium deficiency and could be used in initial complex therapy for pain relief in CP.

Selenoprotein synthesis and side-effects of statins.

2004

Statins are possibly the most effective drugs for the prevention and treatment of hypercholesterolaemia and coronary heart disease. They are generally well tolerated, however, they do cause some unusual side-effects with potentially severe consequences, most prominently myopathy or rhabdomyolysis and polyneuropathy. We noted that the pattern of side-effects associated with statins resembles the pathology of selenium deficiency, and postulated that the mechanism lay in a well established, but often overlooked, biochemical pathway--the isopentenylation of selenocysteine-tRNA([Ser]Sec). A negative effect of statins on selenoprotein synthesis does seem to explain many of the enigmatic effects a…

The 2016 European Thyroid Association/European Group on Graves' Orbitopathy Guidelines for the Management of Graves' Orbitopathy

2015

Graves' orbitopathy (GO) is the main extrathyroidal manifestation of Graves' disease, though severe forms are rare. Management of GO is often suboptimal, largely because available treatments do not target pathogenic mech anisms of the disease. Treatment should rely on a thorough assessment of the activity and severity of GO and its impact on the patient's quality of life. Local measures (artificial tears, ointments and dark glasses) and control of risk factors for progression (smoking and thyroid dysfunction) are recommended for all patients. In mild GO, a watchful strategy is usually sufficient, but a 6-month course of selenium supplementation is effective in improving mild manifestations …

Association of selenium exposure with insulin resistance and β-cell function in middle age and older adults

2021

Soil microbial community response to a selenium chronic exposure

2007

International audience

A Selenium-Nitrogen Chain with Selenium in Different Oxidation States

2017

The reaction of tBuNH2 with a mixture of SeCl2 and SeOCl2 in a 6:2:1 molar ratio produces the novel selenium-nitrogen chain ClSeN(tBu)Se(O)Cl (4), in which the selenium atoms are in two different oxidation states, SeII and SeIV. The crystal structure of 4 is compared with that of the related SeII/SeII system ClSeN(tBu)SeCl (1) and differences are attributed to hyperconjugative effects. The energetics of the formation of 4 via two different routes are elucidated by PBE0/def2-TZVPP calculations. peerReviewed

Formation, Structural Characterization, and Calculated NMR Chemical Shifts of Selenium-Nitrogen Compounds from SeCl4 and ArNHLi (Ar = supermesityl, m…

2004

Supermesityl selenium diimide [Se{N(C6H2tBu3-2, 4, 6)}2; Se{N(mes*)}2] can be prepared in a good yield from the reaction of SeCl4 and (mes*)NHLi. The molecule adopts an unprecedented anti, anti-conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by 77Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C6H2Me3-2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}2 that was characterized by X-ray crystallography and 77Se NMR spectroscopy. The Se-N bonds of 1.847(3) and 1.852(3) A show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indi…