Artykuły w czasopismach na temat „Selenium”
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Zhao, Xiaodan, i Lihao Liao. "Modern Organoselenium Catalysis: Opportunities and Challenges". Synlett 32, nr 13 (11.05.2021): 1262–68. http://dx.doi.org/10.1055/a-1506-5532.
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AbstractOrganoselenium catalysis has attracted increasing interest in recent years. This Cluster highlights recent key advances in this area regarding the functionalization of alkenes, alkynes, and arenes by electrophilic selenium catalysis, selenonium salt catalysis, selenium-based chalcogen-bonding catalysis, and Lewis basic selenium catalysis. These achievements might inspire and help future research.1 Introduction2 Electrophilic Selenium Catalysis3 Selenonium Salt Catalysis4 Selenium-Based Chalcogen-Bond Catalysis5 Lewis Basic Selenide Catalysis6 Conclusion
2
Taskinen, Pekka, Sonja Patana, Petri Kobylin i Petri Latostenmaa. "Oxidation Mechanism of Copper Selenide". High Temperature Materials and Processes 33, nr 5 (29.09.2014): 469–76. http://dx.doi.org/10.1515/htmp-2013-0097.
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AbstractThe oxidation mechanism of copper selenide was investigated at deselenization temperatures of copper refining anode slimes. The isothermal roasting of synthetic, massive copper selenide in flowing oxygen and oxygen – 20% sulfur dioxide mixtures at 450–550 °C indicate that in both atmospheres the mass of Cu2Se increases as a function of time, due to formation of copper selenite as an intermediate product. Copper selenide oxidises to copper oxides without formation of thick copper selenite scales, and a significant fraction of selenium is vaporized as SeO2(g). The oxidation product scales on Cu2Se are porous which allows transport of atmospheric oxygen to the reaction zone and selenium dioxide vapor to the surrounding gas. Predominance area diagrams of the copper-selenium system, constructed for selenium roasting conditions, indicate that the stable phase of copper in a selenium roaster gas with SO2 is the sulfate CuSO4. The cuprous oxide formed in decomposition of Cu2Se is further sulfated to CuSO4.
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Kim, Seung Jo, Min Chul Choi, Jong Min Park i An Sik Chung. "Antitumor Effects of Selenium". International Journal of Molecular Sciences 22, nr 21 (31.10.2021): 11844. http://dx.doi.org/10.3390/ijms222111844.
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Functions of selenium are diverse as antioxidant, anti-inflammation, increased immunity, reduced cancer incidence, blocking tumor invasion and metastasis, and further clinical application as treatment with radiation and chemotherapy. These functions of selenium are mostly related to oxidation and reduction mechanisms of selenium metabolites. Hydrogen selenide from selenite, and methylselenol (MSeH) from Se-methylselenocyteine (MSeC) and methylseleninicacid (MSeA) are the most reactive metabolites produced reactive oxygen species (ROS); furthermore, these metabolites may involve in oxidizing sulfhydryl groups, including glutathione. Selenite also reacted with glutathione and produces hydrogen selenide via selenodiglutathione (SeDG), which induces cytotoxicity as cell apoptosis, ROS production, DNA damage, and adenosine-methionine methylation in the cellular nucleus. However, a more pronounced effect was shown in the subsequent treatment of sodium selenite with chemotherapy and radiation therapy. High doses of sodium selenite were effective to increase radiation therapy and chemotherapy, and further to reduce radiation side effects and drug resistance. In our study, advanced cancer patients can tolerate until 5000 μg of sodium selenite in combination with radiation and chemotherapy since the half-life of sodium selenite may be relatively short, and, further, selenium may accumulates more in cancer cells than that of normal cells, which may be toxic to the cancer cells. Further clinical studies of high amount sodium selenite are required to treat advanced cancer patients.
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AVOSCAN, L., H. KHODJA, M. CARRIÈRE, J. COVÈS i B. GOUGET. "PIXE ANALYSES OF THE SOLUBLE AND MEMBRANE SE-CONTAINING PROTEINS EXTRACTED FROMCUPRIAVIDUS METALLIDURANSCH34 AFTER SELENIUM OXIDES CHALLENGE". International Journal of PIXE 18, nr 03n04 (styczeń 2008): 91–99. http://dx.doi.org/10.1142/s0129083508001430.
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The soil bacterium Cupriavidus metallidurans CH34 resist selenite by reducing it into the insoluble and less toxic elemental selenium. Two mechanisms of reduction of selenium oxides in C. metallidurans CH34 were highlighted: assimilation leading to organic species and detoxification leading to precipitation of selenite in nanoparticules of elemental selenium. The alkyl selenide detected as an intermediate product during assimilation of selenite or as the major accumulated chemical form during assimilation of selenate was identified as selenomethionine.Soluble and membrane proteins were extracted from C. metallidurans CH34 submitted to selenium oxides challenge. After separation by SDS-PAGE, µPIXE analyses were used for Se identification and quantification at a micrometer scale. The profiles of Se distribution in the different samples suggest a non-specific incorporation of selenium probably reflecting the incorporation of selenomethionin in place of the naturally occurring methionin.
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Poluboyarinov, P. A., D. G. Elistratov i V. I. Shvets. "METABOLISM AND MECHANISM OF TOXICITY OF SELENIUM-CONTAINING SUPPLEMENTS USED FOR OPTIMIZING HUMAN SELENIUM STATUS". Fine Chemical Technologies 14, nr 1 (28.02.2019): 5–24. http://dx.doi.org/10.32362/2410-6593-2019-14-1-5-24.
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The work presents a review devoted to the metabolism and the mechanism of toxicity of seleniumcontaining supplements: elemental selenium, sodium selenite, diacetophenonyl selenide, selenopyrane, ebselen, dimethyl dipyrasolyl selenide and selenium-containing amino acids used for correction of selenium deficiency. Elemental selenium penetrating through cell walls, but not through transport channels demonstrates poorly predicted and difficultly regulated bioavailability. Sodium selenate is known to be the most toxic form of selenium in food. The metabolism of xenobiotic diacetophenonyl selenide resembles that of sodium selenide. The xenobiotic reacts with thiols, for instance, with the reduced form of glutathione leading to the formation of hydrogen selenide. Ebselen is not considered to be a well bioavailable form of selenium and thus possesses low toxicity. Xenobiotic selenopyrane eliminates selenium only in processes of xenobiotic liver exchange, and in our investigations - partially in acid-catalyzed hydrolysis. The metabolism of xenobiotic dimethyl dipyrasolyl selenide having low toxicity is poorly investigated. The toxicity of high doses of selenomethionine is determined by the possibility of incorporation in proteins and vitally important enzymes with dramatic changes of protein quaternary structure. The toxicity of high doses of methylselenocysteine seems to be caused by the lack of an exchange pool in the body and quick regeneration of hydrogen selenide from methylselenol which is formed as a result of enzymatic destruction of this amino acid. Also the issue of the most prospect selenium donor is discussed. The physiological compatibility, the low toxicity, the presence of an exchangeable pool in the organism, the antioxidantal properties and the simplicity of production indicate selenocystine as an optimal selenium donor.
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Ball, Sheila, i John Milne. "Studies on the interaction of selenite and selenium with sulfur donors. Part 3. Sulfite". Canadian Journal of Chemistry 73, nr 5 (1.05.1995): 716–24. http://dx.doi.org/10.1139/v95-091.
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Elemental selenium dissolves in sulfite solution to form selenosulfate ion: Se + SO32− = SeSO32−.The formation constants for this equilibrium at temperatures from 0 to 35 °C are reported for the first time. The isomeric thioselenate anion, SSeO32−, is not, however, produced by the reaction of sulfur with selenite nor is the selenoselenate ion, Se2O32−, formed from selenium and selenite. Selenotrithionate is formed rapidly from the reaction of selenous acid with sulfite and hydrogen sulfite according to: HSeO3− + 3 HSO3− = Se(SO3)22− + SO42− + 2H2O.Two isomers of the selenotrithionate ion are observed by Se-77 NMR and Raman spectroscopy, one with O-bonded Se, Se(OSO2)22−, and the other with S-bonded Se, Se(SO3)22−. Both isomers are formed in reactions with hydrogen sulfite but only the O-bonded isomer is formed in sulfite solutions at ambient temperatures. The Raman and Se-77 NMR spectra of the various sulphur–selenium anions formed are given and the parallel with the reactions of selenous acid and thiols is discussed. Keywords: selenium, sulfite, selenosulfate, selenotrithionate, Se-77 NMR, Raman spectroscopy, equilibria, aqueous solutions.
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Danscher, Gorm, i Meredin Stoltenberg. "Zinc-specific Autometallographic In Vivo Selenium Methods: Tracing of Zinc-enriched (ZEN) Terminals, ZEN Pathways, and Pools of Zinc Ions in a Multitude of Other ZEN Cells". Journal of Histochemistry & Cytochemistry 53, nr 2 (luty 2005): 141–53. http://dx.doi.org/10.1369/jhc.4r6460.2005.
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In vivo-applied sodium selenide or sodium selenite causes the appearance of zinc-selenium nanocrystals in places where free or loosely bound zinc ions are present. These nanocrystals can in turn be silver enhanced by autometallographic (AMG) development. The selenium method was introduced in 1982 as a tool for zinc-ion tracing, e.g., in vesicular compartments such as synaptic vesicles of zinc-enriched (ZEN) terminals in the central nervous system, and for visualization of zinc ions in ZEN secretory vesicles of, e.g., somatotrophic cells in the pituitary, zymogene granules in pancreatic acinar cells, beta-cells of the islets of Langerhans, Paneth cells of the crypts of Lieberkühn, secretory cells of the tubuloacinar glands of prostate, epithelium of parts of ductus epididymidis, and osteoblasts. If sodium selenide/selenite is injected into brain, spinal cord, spinal nerves containing sympathetic axons, or intraperitoneally, retrograde axonal transport of zinc-selenium nanocrystals takes place in ZEN neurons, resulting in accumulation of zinc-selenium nanocrystals in lysosomes of the neuronal somata. The technique is, therefore, also a highly specific tool for tracing ZEN pathways. The present review includes an update of the 1982 paper and presents evidence that only zinc ions are traced with the AMG selenium techniques if the protocols are followed to the letter.
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Anderson, Kim A., i Brandon Isaacs. "Determination of Selenium in Feeds, Premixes, Supplements, and Injectable Solutions by Hydride-Generated Inductively Coupled Plasma Atomic Emission Spectrometry". Journal of AOAC INTERNATIONAL 76, nr 4 (1.07.1993): 910–13. http://dx.doi.org/10.1093/jaoac/76.4.910.
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Abstract A simple method is described for the determination of 0.01-30 000 μg selenium/g sample. Selenium is present in feed supplements, premixes, mineral mixes, and injectable solution as either selenite or selenate. High concentrations of other common minerals present in these supplements are tolerated by the method. The samples are initially digested by heating with nitric acid and then boiled in a mixture of sulfuric and perchloric acids to convert all selenium species to selenate. The selenate is reduced to selenite, Se (IV), with hydrochloric acid at 95°C. The selenite in turn is then reduced by acidic sodium borohydride to hydrogen selenide, which is measured by hydride-generated inductively coupled plasma atomic emission spectrometry at 196.026 nm. The instrument detection limit for this method is 0.0005 μg Se/g sample.
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Amaratunga, W., O. Chaudry i J. Milne. "Studies on the interaction of selenite and selenium with sulphur donors. Part 1. 2-Mercaptoethanol". Canadian Journal of Chemistry 72, nr 4 (1.04.1994): 1165–70. http://dx.doi.org/10.1139/v94-149.
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Raman spectroscopy and proton and 77Se NMR have been used to show that selenous acid reacts with 2-mercaptoethanol (HOC2H4SH), according to Ganther's reaction (H.E. Ganther, Biochemistry, 7, 2898 (1968)).[Formula: see text]The bis(hydroxyethylthio)selenide decomposes readily in strongly acidic and moderately basic solution to selenium and disulfide,[Formula: see text]Selenium dissolves in excess hydroxyethylmercaptide to give the catenated anion, HOC2H4SSe−[Formula: see text]Air oxidation of this equilibrium mixture yields disulfide and selenium. Formation of the hydroxyethylthioselenide is endothermic (ΔH = 0.66 ± 0.02 kJ mol−1).
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Eom, Taejun, i Anzar Khan. "Selenium-Epoxy ‘Click’ Reaction and Se-Alkylation—Efficient Access to Organo-Selenium and Selenonium Compounds". Chemistry 2, nr 4 (5.10.2020): 827–36. http://dx.doi.org/10.3390/chemistry2040054.
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This work establishes the ‘click’ nature of the base-catalyzed oxirane ring opening reaction by the selenolate nucleophile. The ‘click’-generated ß-hydroxy selenide can be alkylated to afford cationic selenium species. Hemolytic studies suggest that selenonium cations do not lyse red blood cells even at high concentrations. Overall, these results indicate the future applicability of the developed organo-selenium chemistry in the preparation of a new class of cationic materials based on the seleno-ether motif.
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Francisco Sánchez-Viesca i Reina Gómez. "The mechanism of Mecke’s test for opioids". World Journal of Chemical and Pharmaceutical Sciences 2, nr 1 (30.01.2023): 023–27. http://dx.doi.org/10.53346/wjcps.2023.2.1.0014.
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Mecke colour test is an official assay for opioids, either for opium or for purified compounds. It employs a solution of selenious acid in sulphuric acid. However, organoselenium chemistry was misunderstood for many years. The reaction mechanism involving selenium (IV) compounds was explained by way of electron back donation, which is a theoretical contravention. In this communication we provide the reactions that take place during this test. Each step is fully commented and the electron flow is given. The reaction proceeds by way of an enol selenite. Acidolysis gives rise to a reduced selenium (II) intermediate and an activated ketone at C-2, that is, a redox reaction with polarity inversion. Addition of selenious acid and further electron shifts affords morphine ortho-quinone and elemental selenium.
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Liu, Simei, Shili Ye, Peng Zhao i Lihua Zhang. "Synthesis and Preliminary Biological Activity of Selenium Polysaccharides from Tussilago farfara L." Journal of Physics: Conference Series 2706, nr 1 (1.02.2024): 012065. http://dx.doi.org/10.1088/1742-6596/2706/1/012065.
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Abstract Tussilago farfara L. selenium polysaccharides (STFPs, similarly hereinafter) were prepared by Selenous acid salt method from Tussilago farfara L. polysaccharide (TFP, similarly hereinafter). Taking the selenium content of STFPs as an indicator, the synthesis process of STFPs was optimized using response surface methodology based on single factor experiments. The optimal synthesis process conditions obtained are: 90 °C, 12 hours, selenide reagent ratio of 1.2: 1, HNO3 volume fraction of 0.7%, and the average selenium content of STFPs measured under these conditions is 2.338 mg/g. Characterization was carried out by measuring the selenium content, molecular weight, infrared spectroscopy. The results of antioxidant experiments showed that the maximum clearance rate of DPPH· by the selenium polysaccharide from Tussilago farfara L. was 73.16%, which were higher than from Tussilago farfara L. polysaccharides.
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Jin, Weihong, Cheolho Yoon, Tony Johnston, Seockmo Ku i Geun Ji. "Production of Selenomethionine-Enriched Bifidobacterium bifidum BGN4 via Sodium Selenite Biocatalysis". Molecules 23, nr 11 (2.11.2018): 2860. http://dx.doi.org/10.3390/molecules23112860.
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Selenium is a trace element essential for human health that has received considerable attention due to its nutritional value. Selenium’s bioactivity and toxicity are closely related to its chemical form, and several studies have suggested that the organic form of selenium (i.e., selenomethionine) is more bioavailable and less toxic than its inorganic form (i.e., sodium selenite). Probiotics, especially Bifidobacteriium and Lactobacillus spp., have received increasing attention in recent years, due to their intestinal microbial balancing effects and nutraceutical benefits. Recently, the bioconversion (a.k.a biotransformation) of various bioactive molecules (e.g., minerals, primary and secondary metabolites) using probiotics has been investigated to improve substrate biofunctional properties. However, there have been few reports of inorganic selenium conversion into its organic form using Bifidobacterium and Lactobacillus spp. Here we report that the biosynthesis of organic selenium was accomplished using the whole cell bioconversion of sodium selenite under controlled Bifidobacterium bifidum BGN4 culture conditions. The total amount of organic and inorganic selenium was quantified using an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The selenium species were separated via anion-exchange chromatography and analyzed with inductively coupled plasma-mass spectrometry (ICP-MS). Our findings indicated that the maximum level of organic selenium was 207.5 µg/g in selenium-enriched B. bifidum BGN4. Selenomethionine was the main organic selenium in selenium-enriched B. bifidum BGN4 (169.6 µg/g). Considering that B. bifidum BGN4 is a commercial probiotic strain used in the functional food industry with clinically proven beneficial effects, selenium-enriched B. bifidum BGN4 has the potential to provide dual healthy functions as a daily supplement of selenium and regulator of intestinal bacteria. This is the first report on the production of organic selenium using B. bifidum spp.
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Ramin, A. G., S. Asri-Rezaie i A. Hajili. "Correlations between Sodium Selenite and Vitamin E with Serum Macro-Minerals in Male Lambs". Folia Veterinaria 66, nr 2 (1.06.2022): 70–79. http://dx.doi.org/10.2478/fv-2022-0020.
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Abstract The effects of selenium and vitamin E (Vit. E) were evaluated on the macro-elements and their relationships were also surveyed. Lambs were divided into 4 groups of control, Vit. E, sodium selenite and sodium selenite/Vit. E (Se/E). Sodium selenite (0.1 mg.kg−1) and Vit. E (8 mg.kg−1) were administered. The mean blood selenium was high in sodium selenite. Selenium only in the Se groups was continuously increased. The lowest and highest blood selenium were in Vit. E and sodium selenite, respectively. The mean serum macro-minerals were within the normal range. The trend of calcium and magnesium in the selenium groups was to increase until day 60, but phosphorus was to decline. The lowest and highest calcium were observed in the control and sodium selenite groups, for magnesium in Vit. E and control groups, and for inorganic phosphorus were in the control group, respectively. The comparison of minerals showed that selenium had a significant increase from day 14 to 90 in sodium selenite. Selenium showed the most positive relationships with calcium and inorganic phosphorus in Vit. E and sodium selenite. Overall, selenium was correlated with macro-minerals on day 90 and overall sampling times were with calcium. In conclusion, administration of selenium with Vit. E increased selenium, which was more observed in the sodium selenite group. Sodium selenite alone or with Vit. E had no effect on the macro-minerals. The least correlation was observed between selenium and macro-minerals in the Se/E administration. The correlation between macro-minerals was positive. It was concluded that the effect of sodium selenite on treatment and prevention of selenium deficiency was more effective than other groups. Vit. E per selenium did not change the selenium concentration. Selenium administration was associated with an increase in calcium level and their co-administration is recommended.
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Abduali, Baeshov, Ivanov Nikolay i Myrzabekov Begzat. "Electrochemical Behavior of Selenium as Part of Composite Electrode in Sulfuric Acid Medium". JOURNAL OF ADVANCES IN CHEMISTRY 7, nr 3 (17.12.2011): 1378–84. http://dx.doi.org/10.24297/jac.v7i3.2373.
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The method of productiion of the composite selenium-graphitic electrodes based on organic polymer binder was proposed. Electrochemical behavior of the elementary selenium as content of composite electrode in sulfuric acid medium was assessed. A formation of hydrogen selenide during the cathode polarization, and formation of selenite and selenate ions was shown. An influence of potential spread velocity, acid concentration, and temperature of electrolyte were evaluated. Effective activation power for cathode process was estimated using the temperature-cathodic method.
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GLOTOVA, I. A., N. A. GALOCHKINA, V. F. SELEMENEV, O. V. PEREGONCHAYA i S. A. SOKOLOVA. "IR-SPECTROSCOPIC STUDY OF IMMOBILIZATION OF SELENIUM COMPOUNDS ON BIOMODIFIED COLLAGEN". Periódico Tchê Química 16, nr 33 (20.03.2019): 159–68. http://dx.doi.org/10.52571/ptq.v16.n33.2019.174_periodico33_pgs_159_168.pdf.
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The aim of the work was to research the spectral characteristics of collagen substances bioengineered by using complex collagenolytic proteases preparation obtained before and after the immobilization of selenium compounds in acidic and alkaline media and to comparate the degree of interaction of selenium preparations with collagen matrix upon immobilization and its influence on the conformation of protein molecules. The results of the immobilization of selenium preparations on biomodified collagen by the IR spectroscopy method are presented, analyzed, and discussed. Biomodified collagen was obtained from beef trimming waste (veins and tendons) by sequential peroxide-alkaline and enzymatic hydrolysis with the food collagenase preparation. The following sources of selenium were used as compounds with bioprotective properties for subsequent immobilization on biomodified collagen proteins: 4,4-di[3(5-methyldiprazolil)]selenide (DMDPS) with the content of 0,657g DMDMS in 100 cm3 and sodium selenite. Spectrograms are carried out for products of biomodification of collagen before sorption of compounds of selenium, (at the rate of 1.2 g-6 of selenium on 1 g of collagen) in acid (рН =5) and alkaline (рН =10) environments at a research of influence of compounds of selenium on IR spectrums of products of biomodification of collagen. It was established, that the immobilization takes place by a chemical reaction of selenium preparations with functional groups of the side chains of protein molecules, and its degree varies in the range Na2SeO3 (pH=5) > 4,4-di[3(5-methyldiprazolil)]selenide (DMDPS) > Na2SeO3 (pH=10). It is shown that under the interaction of selenium products with collagen, there is no change in the conformations of its molecules occurred.
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Müller-Simon, Hayo, i Peter Griebenow. "Behavior of Zinc Selenite, Calcium Selenite and Metallic Selenium as Decolorizing Agents in Flint Glass Production". Advanced Materials Research 39-40 (kwiecień 2008): 541–46. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.541.
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Zinc selenite, calcium selenite and metallic selenium have been consecutively introduced as decolorizing agents in a flint glass production. The selenium concentration in the glass has been measured by wet-chemical analysis, optically by the evaluation of the cielab a-value and electrochemically by means of a voltammetric sensor. All measuring techniques showed the highest selenium retention for calcium selenite followed by zinc selenite and the least retention using metallic selenium. The best reproducibility is achieved using zinc selenite while both calcium selenite and metallic selenium provide only poor reproducibility.
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Cemeli, Eduard, Ricard Marcos i Diana Anderson. "Genotoxic and antigenotoxic properties of selenium compounds in thein vitromicronucleus assay with human whole blood lymphocytes and tk6 lymphoblastoid cells". Scientific World JOURNAL 6 (2006): 1202–10. http://dx.doi.org/10.1100/tsw.2006.204.
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Selenium is known to possess both genotoxic and antigenotoxic properties. In the present study, we have evaluated the genotoxicity and antigenotoxicity of three selenium compounds (sodium selenate, sodium selenite and selenous acid) by measuring in vitro micronucleus induction. Assays were conducted in whole blood lymphocytes and in the TK6 lymphoblastoid cell line, with and without co-treatment with potassium dichromate, a known genotoxic compound. In general, the compounds were more active in TK6 cells than they were in blood lymphocytes. Only 1 μM selenous acid increased the frequency of binucleated cells containing micronuclei (BNMN) in blood lymphocytes, while all three selenium compounds increased BNMN in TK6 cells. In addition, combinations of selenous acid and potassium dichromate resulted in lower frequencies of BNMN than potassium dichromate alone in blood lymphocytes, while combinations of sodium selenate and potassium dichromate produced lower frequencies of BNMN than potassium dichromate alone in TK6 cells. The concentrations of selenium compounds that were used, in combination with the medium components and the biological physiology of the whole blood lymphocytes and TK6 cells, could have affected the redox potential of the compounds, switching the chemicals from a pro-oxidant to antioxidant status and vice-versa. The lower activities of the compounds in blood lymphocytes may be due to the protective effects of blood components. The results indicate that the genotoxic and antigenotoxic properties of selenium compounds are highly dependent upon the conditions under which they are evaluated.
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Ranjard, Lionel, Sylvie Nazaret i Benoit Cournoyer. "Freshwater Bacteria Can Methylate Selenium through the Thiopurine Methyltransferase Pathway". Applied and Environmental Microbiology 69, nr 7 (lipiec 2003): 3784–90. http://dx.doi.org/10.1128/aem.69.7.3784-3790.2003.
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ABSTRACT Involvement of the bacterial thiopurine methyltransferase (bTPMT) in natural selenium methylation by freshwater was investigated. A freshwater environment that had no known selenium contamination but exhibited reproducible emission of dimethyl selenide (DMSe) or dimethyl diselenide (DMDSe) when it was supplemented with an organic form of selenium [(methyl)selenocysteine] or an inorganic form of selenium (sodium selenite) was used. The distribution of the bTPMT gene (tpm) in the microflora was studied. Freshwater bacteria growing on 10 μM sodium selenite and 10 μM sodium selenate were isolated, and 4.5 and 10% of the strains, respectively, were shown by colony blot hybridization to hybridize with a Pseudomonas syringae tpm DNA probe. Ribotyping showed that these strains are closely related. The complete rrs sequence of one of the strains, designated Hsa.28, was obtained and analyzed. Its closest phyletic neighbor was found to be the Pseudomonas anguilliseptica rrs sequence. The Hsa.28 strain grown with sodium selenite or (methyl)selenocysteine produced significant amounts of DMSe and DMDSe. The Hsa.28 tpm gene was isolated by genomic DNA library screening and sequencing. BLASTP comparisons of the deduced Hsa.28 bTPMT sequence with P. syringae, Pseudomonas aeruginosa, Vibrio cholerae, rat, and human thiopurine methyltransferase sequences revealed that the levels of similarity were 52 to 71%. PCR-generated Escherichia coli subclones containing the Hsa.28 tpm open reading frame were constructed. E. coli cells harboring the constructs and grown with sodium selenite or (methyl)selenocysteine produced significant levels of DMSe and DMDSe, confirming that the gene plays a role in selenium methylation. The effect of strain Hsa.28 population levels on freshwater DMSe and DMDSe emission was investigated. An increase in the size of the Hsa.28 population was found to enhance significantly the emission of methyl selenides by freshwater samples supplemented with sodium selenite or (methyl)selenocysteine. These data suggest that bTPMT can play a role in natural freshwater selenium methylation processes.
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Shurygina, I. A., N. N. Dremina, I. S. Trukhan i M. G. Shurygin. "SELENIUM IN NANOFORM: TOXICITY AND SAFETY". Baikal Medical Journal 1, nr 1 (2022): 24–32. http://dx.doi.org/10.57256/2949-0715-2022-1-24-32.
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The review is devoted to the compilation of data on the toxicity and safety of using nanosized forms of selenium. It is shown that in nature selenium exists mainly in the form of selenate (Se6+), selenite (Se4+), selenide (Se2–) and elemen-tal selenium (Se0), while the latter is insoluble in aqueous media, less toxic and biologically inert. Elemental selenium in the form of nanosized particles is not only biocompatible, but also has antitumor and antimicrobial activity. It was shown that elemental selenium in the form of nanoparticles can modulate the activity of the antioxidant and detoxification systems. A data on the dose-dependent effect of selenium in nanosized form was presented. It was demonstrated that selenium nanoparticles in high concentrations (above 2 mg of Se per 1 kg of animal weight) can cause the development of selenium-induced toxicity in mammals. It was shown that elemental selenium in the form of nanoparticles can affect immunoregulation, reproductive func-tion, kidney and liver function, can modulate the activity of the antioxidant and detoxification systems, and in high concentrations (above 2 mg of Se per 1 kg of animal weight) it can cause the development of selenium-induced toxicity both in mammals and fish. At the same time, it was shown that for fish selenium nanoparticles are more toxic than inorganic selenium and cause a more acute reaction of the body to exposure to even low concentrations, which is possibly associated with hyperaccumulation of selenium in tissues. This fact once again reminds us of the need to take into account the problems of ecotoxicity of selenium nanocomposites.
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Christensen, M. K., C. J. Frederickson i G. Danscher. "Retrograde tracing of zinc-containing neurons by selenide ions: a survey of seven selenium compounds." Journal of Histochemistry & Cytochemistry 40, nr 4 (kwiecień 1992): 575–79. http://dx.doi.org/10.1177/40.4.1313065.
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The autometallographic retrograde tracing of zinc-containing neurons by intracerebral injection of sodium selenite (Na2SeO3), introduced by Danscher in 1982, has recently been described in more detail. Intracerebral injections of both sodium selenide (Na2Se) and sodium selenite (Na2SeO3) have been successfully used; however, sodium selenite had a rather toxic effect on the injected tissue. In the present study, we tested seven different selenium compounds to find the most suitable compound for retrograde tracing of zinc-positive pathways. Among the tested compounds, sodium selenide (Na2Se) caused insignificant necrosis within the injection site and was easily transported retrogradely when handled anaerobically. Sodium selenide is therefore recommended as the compound of choice.
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Wen, Su, Yang Hui i Wang Chuang. "Biosynthesis and antioxidation of nano-selenium using lemon juice as a reducing agent". Green Processing and Synthesis 10, nr 1 (1.01.2021): 178–88. http://dx.doi.org/10.1515/gps-2021-0018.
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Abstract Nano-selenium was synthesized using lemon juice as a reducing agent. The experiments showed that pH value affected greatly the shape and the size of the prepared nano-selenium. At pH 9, lemon juice could reduce 50 mmol/L of selenite ions to nano-selenium with particle size between 50 and 90 nm, which was spherical and well dispersed. Lemon juice acted as both a reducing agent and a stabilizer in the synthesis of nano-selenium, in which the chemical interaction between biomolecules and the nano-selenium surface was the basis for the stable existence of nano-selenium. The selenite concentration influenced the formation of nano-selenium, and a low selenite concentration was beneficial to obtain small particles. The achieved nano-selenium exhibited a strong antioxidant activity positively related to concentration. The comparative study showed that the antioxidation of nano-selenium is weaker than that of vitamin C but higher than that of lemon juice.
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Yoshinaga, Masafumi, Stephanie How, Damien Blanco, Ian Murdoch, Matteo Grudny, Samantha Powers, Nelson Molina, Barry Rosen i Aaron Welch. "Directed Evolution of Saccharomyces cerevisiae for Increased Selenium Accumulation". Microorganisms 6, nr 3 (6.08.2018): 81. http://dx.doi.org/10.3390/microorganisms6030081.
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Selenium-enriched yeast (selenium yeast) are one of the most popular sources of selenium supplementation used in the agriculture and human nutritional supplements industries. To enhance the production efficiency of selenium yeast, we sought to develop a method to identify, and ultimately select for, strains of yeast with enhanced selenium accumulation capabilities. Selenite resistance of four genetically diverse strains of Saccharomyces cerevisiae was assayed in various conditions, including varying carbon sources, nitrogen sources, and phosphate amounts, and they were correlated with selenium accumulation in a commercially relevant selenium-containing growth medium. Glycerol- and selenite-containing media was used to select for six yeast isolates with enhanced selenite resistance. One isolate was found to accumulate 10-fold greater selenium (0.13 to 1.4 mg Se g−1 yeast) than its parental strain. Glycerol- and selenium-containing medium can be used to select for strains of yeast with enhanced selenium accumulation capability. The methods identified can lead to isolation of industrial yeast strains with enhanced selenium accumulation capabilities that can result in greater cost efficiency of selenium yeast production. Additionally, the selection method does not involve the construction of transgenic yeast, and thus produces yeasts suitable for use in human food and nutrient supplements.
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Jiang, Xiaoyu, Liu Yang, Yinghui Wang, Fajun Jiang, Junxiang Lai i Kailin Pan. "Proteomics Provide Insight into the Interaction between Selenite and the Microalgae Dunaliella salina". Processes 11, nr 2 (13.02.2023): 563. http://dx.doi.org/10.3390/pr11020563.
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Dunaliella salina is currently one of the most commercially valuable microalgae species in the world. In reponse to selenite, D. salina is a microalgae with a high selenium content, thereby increasing its value, which is crucial for increasing its economic value as a nutrional supplement. However, the effects of selenite on D. salina are still unclear, and its molecular mechanism of the response to selenite stress is also elusive. Here, in order to study the effects of selenite on D. salina and the corresponding regulatory mechanism, we characterized the physiological phenotypes of D. salina under different selenite concentrations and carried out a quantitative proteomic study. The results showed that the effective concentration for 50% growth inhibition (EC50) of the algae was 192.7 mg/L after 11 days of cultivation. When selenite concentration was lower than 100 mg/L, selenite did not hinder the growth of D. salina in the early stage, but shortened the cell growth cycle, although cell growth was significantly inhibited when the concentration of selenium was higher than 250 mg/L. Bioaccumulation experiments showed that the content of intracellular selenium in D. salina cells reached the highest level under the treatment with 50 mg/L selenite, and the contents of total selenium and organic selenium in D. salina cells were 499.77 μg/g and 303.01 μg/g (dry weight), respectively. Proteomic analysis revealed that a series of proteins related to stress responses, amino acid metabolism and energy production pathways were profoundly altered by the selenite treatment. Glutathione peroxidase (GPX7), a selenium-containing protein, was identified in the group given the selenium treatment. Moreover, proteins involved in photoreactions and oxidative phosphorylation were significantly upregulated, indicating that D. salina effectively balanced the energy demand and energy production under selenite stress. This study provides novel insights into the responses to selenite of D. salina, a microalgae candidate as a biological carrier of selenium and would be helpful for the development of industrial strains rich in selenium.
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Faixová, Zita, Elena Piešová, Zuzana Maková, Klaudia Čobanová i Štefan Faix. "Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on ruminal enzyme activities and blood chemistry in sheep". Acta Veterinaria Brno 85, nr 2 (2016): 185–94. http://dx.doi.org/10.2754/avb201685020185.
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The experiment was conducted to evaluate the effect of feeding a diet supplemented with different forms of selenium on the rumen fluid, blood and serum enzyme activity and osmotic fragility of red blood cells in sheep. The experiment was carried out on 18 sheep of the Valashka breed at the age of 18 months, divided into 3 groups. The first group was given basal diet (BD) with a Se content of 0.17 mg/kg of dry matter (DM). The second group received BD supplemented with 0.4 mg Se/kg of (DM) in the form of sodium selenite. The third group received BD supplemented with 0.4 mg Se/kg of (DM) in the form of Se-yeast extract. Duration of the trial was 12 weeks. Selenium concentration in blood and total rumen fluid were elevated in both supplemented groups with the highest values in Se-yeast-treated sheep. Blood glutathione peroxidase (GPx) activity was significantly increased, regardless of the source of selenium. Osmotic resistance of red blood cells was not affected by selenium supplementation. The results indicate that feeding a diet supplemented with selenium from Se-yeast or selenite improved selenium status in blood and total rumen fluid. Selenium from sodium selenite was as effective as selenium from Se-yeast in the availability of selenium for the blood GPx activity. The effect of selenium supplementation on the ruminal enzyme activity depends on the selenium form; GGT and GDH were significantly higher in the Se-yeast supplement group, AST and ALP were significantly higher in the selenite supplement group.
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Samra, Kavitej, Mathun Kuganesan, William Smith, Anna Kleyman, Robert Tidswell, Nishkantha Arulkumaran, Mervyn Singer i Alex Dyson. "The Pharmacology and Therapeutic Utility of Sodium Hydroselenide". International Journal of Molecular Sciences 22, nr 6 (23.03.2021): 3258. http://dx.doi.org/10.3390/ijms22063258.
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Metabolically active gasotransmitters (nitric oxide, carbon monoxide and hydrogen sulfide) are important signalling molecules that show therapeutic utility in oxidative pathologies. The reduced form of selenium, hydrogen selenide (HSe−/H2Se), shares some characteristics with these molecules. The simple selenide salt, sodium hydroselenide (NaHSe) showed significant metabolic activity, dose-dependently decreasing ex vivo O2 consumption (rat soleus muscle, liver) and transiently inhibiting mitochondrial cytochrome C oxidase (liver, heart). Pharmacological manipulation of selenoprotein expression in HepG2 human hepatocytes revealed that the oxidation status of selenium impacts on protein expression; reduced selenide (NaHSe) increased, whereas (oxidized) sodium selenite decreased the abundance of two ubiquitous selenoproteins. An inhibitor of endogenous sulfide production (DL-propargylglycine; PAG) also reduced selenoprotein expression; this was reversed by exogenous NaHSe, but not sodium hydrosulfide (NaHS). NaHSe also conferred cytoprotection against an oxidative challenge (H2O2), and this was associated with an increase in mitochondrial membrane potential. Anesthetized Wistar rats receiving intravenous NaHSe exhibited significant bradycardia, metabolic acidosis and hyperlactataemia. In summary, NaHSe modulates metabolism by inhibition of cytochrome C oxidase. Modification of selenoprotein expression revealed the importance of oxidation status of selenium therapies, with implications for current clinical practice. The utility of NaHSe as a research tool and putative therapeutic is discussed.
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T, Asmidha, Rajeshkumar S, T. Lakshmi i Sulochana G. "Free Radical Scavenging Activity of Clove and Cumin Formulation Mediated Selenium Nanoparticl". Journal of Complementary Medicine Research 14, nr 3 (2023): 81. http://dx.doi.org/10.5455/jcmr.2023.14.03.14.
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Background: Selenium nanoparticles (SeNPs) have the potential to be used for various applications.The green SeNPs (selenium nanoparticles) are formed by simple mixing Withania somnifera (W. somnifera) leaves extract and selenious acid (H2SeO3) solution. Nanoparticles have revolutionized for targeted drug delivery by minimizing the toxicity and side effects that commercially available drugs may have on patients. In this study we have chosen the clove and cumin because it protects from cholesterol, inflammatory damage and it has antioxidant property Aim: The aim of the study is to analyze the antioxidant activity of clove and cumin formulation mediated selenium nanoparticles. Materials & Methods: Cumin and Clove were powdered and stored in an air-sealed container. 1g of cumin and clove formulation was mixed with 100 ml of distilled water and boiled for 15 minutes and the formulation was filtered with Whatmann No.1 filter paper. 30mM sodium selenite was prepared in 50 ml of distilled water. 50 ml of sodium selenite solution and 50 ml of clove and cumin formulation was mixed and kept in a rotary shaker for 48 hours. UV spectroscopy reading based on color change was observed. Results: The antioxidant effect of selenium nanoparticles showed a higher percentage of inhibition at 50µg/ml in DPPH Assay and H2O2 Assay. The clove and cumin extract showed an increased percentage of inhibition with increasing concentration. Conclusion: The clove and cumin formulation mediated selenium nanoparticles acts as potent antioxidant agents. It also has the least side effects compared to commercial drugs.
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Hurlbut, Jeffrey A., Roger G. Burkepile i Carolyn A. Geisler. "Colorimetric Determination of Selenium in Premixes and Supplements". Journal of AOAC INTERNATIONAL 75, nr 2 (1.03.1992): 269–71. http://dx.doi.org/10.1093/jaoac/75.2.269.
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Abstract A colorimetric method Is described for the determination of 100-10 000 μg selenlum/g premix. Selenium Is present in premixes as either selenite or selenate. Moderate to high concentrations of several common minerals are tolerated. The premix is briefly digested In a sulfuric acid-perchloric acidsodium molybdate mixture, boiled in 10% NaCI solution, made basic, and centrifuged. Aliquots are taken if necessary. The mixture Is then acidified with formic acid, treated with hydroxylamlne hydrochlorlde- EDTA, and complexed with 3,3 - dlamlnobenzldlne. The pH Is adjusted, and an extraction Is performed with toluene. The absorbance is measured at 420 nm. Recoveries for 100- 10 000 μg selenlum/g premix ranged from 88 to 104%, with an average of 97%. The coefficient of variation ranged from 1.6 to 6.9%, with an average of 4.2%.
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Eisenberg, Sylvan. "Relative Stability of Selenites and Selenates in Feed Premixes as a Function of Water Activity". Journal of AOAC INTERNATIONAL 90, nr 2 (1.03.2007): 349–53. http://dx.doi.org/10.1093/jaoac/90.2.349.
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Abstract Sodium selenite is more hygroscopic than sodium selenate. It is, therefore, more likely to dissolve when dispersed in feeds of relatively high water activity. When dissolved, it may form selenious acid and disperse as a vapor. This is easily demonstrated by mounting a filter paper wetted with a reagent such as ascorbic acid over the subject feed, but not in contact with it. The paper turns brown as elemental selenium is formed from reduction of the vapor. Analysis of the paper ensures that the brown is indeed selenium. Though premixes are generally low enough in moisture content to ensure stability of the selenites, this is not true of many feeds. The water activities of a number of feeds, feed premixes, and feed ingredients have been determined instrumentally and compared to those of saturated solutions of sodium selenite and sodium selenate. There is no question that the selenite often dissolves with the potential to react and, in so doing, loses its nutritional function.
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Kulasekara, Herath Mudiyanselage Ishani P., Yanyan Zhang i Charalambos Papelis. "Microbial Enhancement of Selenium Removal in Chemically Modified Zeolite Columns". Water 15, nr 10 (11.05.2023): 1837. http://dx.doi.org/10.3390/w15101837.
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Selenium (Se) is an essential micro-nutrient for living organisms, but elevated concentrations in water can adversely affect health. In this research, we investigate the removal of selenium oxyanions (selenate and selenite) in aqueous systems by integration of adsorption on modified zeolites and microbial reduction. Dynamic sorption-reduction experiments were conducted using two sets of zeolite columns for the removal of selenite and selenate oxyanions, respectively. In each case, one column was fully packed with natural, unmodified zeolites, while the other column was composed of 80% natural and 20% iron-coated zeolites, by mass. The initial selenium concentration, selenite (SeIV) or selenate (SeVI), was 790 μg/L, the pH was 7.5, and the flow rate was 3 mL/min. Initially, as expected, the higher selenate removal (34%) was observed with coated zeolite, twice as high compared to the results with unmodified zeolite. Maximum selenite removal was 89% in the column with modified zeolite. Within approximately 14 days, as the biofilm developed inside the columns, selenium reduction in all four columns reached approximately 99%. Biofilm microbial community composition, assessed by 16S rRNA sequencing, is consistent with the presence of mainly selenium-reducing bacteria (Veillonella, Bacteroides, and Escherichia). Selenium oxyanions were reduced to elemental selenium, visible within the bioreactors as red-color aggregates.
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Misurova, L., L. Pavlata, A. Pechova i R. Dvorak. "Effect of a long-term peroral supplementation with sodium selenite and selenium lactate-protein complex on selenium status in goats and their kids". Veterinární Medicína 54, No. 7 (18.08.2009): 324–32. http://dx.doi.org/10.17221/107/2009-vetmed.
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The aim of this study was to evaluate the effect of a long-term peroral selenium supplementation in the form of sodium selenite and selenium lactate-protein complex by comparing selenium concentrations and glutathione peroxidase activity in blood of goats and their kids as well as comparing selenium concentrations in goat colostrums. For the study, a total of 27 clinically healthy pregnant white shorthair goats were used. They were divided to three groups, i.e., the control group (C) without any selenium supplementation, sodium selenite group (E1) and selenium lactate-protein complex group (E2). For four months, experimental goats received 0.43 mg of selenium per animal per day in diet; goats from the control group were given 0.15 mg of selenium per animal per day. At the beginning of the experiment, goats of all groups showed an average selenium concentration of 96 μg/l in whole blood. On the parturition day, samples of first colostrum from goats and heparinized blood from goats and kids were taken. In the control group (C), average blood selenium concentrations of 111.4 ± 33.5 μg/l were observed on the parturition day. In both experimental groups, selenium concentrations were significantly higher (<I>P</I> < 0.05). Average selenium concentration in the sodium selenite group (E1) was 177.2 ± 34.8 μg/l and in the group supplemented with selenium lactate-protein complex (E2) 159.0 ± 28.5 μg/l. Average glutathione peroxidase (GSH-Px) activity in blood of control goats (C) was 581.9 ± 99.2 μkat/l, in group E1 1 154.6 ± 156.2 μkat/l and in group E2 1 011.6 ± 153.6 μkat/l. GSH-Px activity in experimental groups was significantly higher (<I>P</I> < 0.05) as compared with the control group. Average selenium concentrations in colostrum was in the control group 40.1 ± 12.8 μg/l, in E1 99.0 ± 29.9 μg/l and in group E2 79.0 ± 17.7 μg/l. Colostral selenium concentrations in experimental groups were significantly higher (<I>P</I> < 0.05) as compared with the control group. No significant difference in the monitored parameters was found between experimental groups. In kids of control mothers (kC), average selenium concentrations in blood on the parturition day were 62.4 ± 22.9 μg/l; kids of mothers supplemented with sodium selenite (kE1) showed average selenium levels of 100.0 ± 31.2 μg/l, and the average selenium concentration in kids of mothers receiving lactate-protein complex was 83.4 ± 20.1 μg/l (kE2). Average GSH-Px activity in control kids (kC) was 402.1 ± 153.9 μkat/l. Kids from kE1 showed average activity of GSH-Px 806.1 ± 254.9 μkat/l and kids from group kE2 529.9 ± 119.8 μkat/l. Statistically significant difference (<I>P</I> < 0.05) was found only between kC and kE1 which showed significantly higher selenium concentration and GSH-Px activity. The results of this study confirm that both forms of selenium administered in experimental groups (i.e., sodium selenite and selenium lactate-protein complex) had similar biological effect in goats. However, results obtained in kids indicate a better effect of supplementation with sodium selenite.
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Wang, Yidan, Yonghe Yu, Yuhua Duan, Qin Wang, Xin Cong, Yi He, Chao Gao i in. "Enhancing the Activity of Carboxymethyl Cellulase Enzyme Using Highly Stable Selenium Nanoparticles Biosynthesized by Bacillus paralicheniformis Y4". Molecules 27, nr 14 (18.07.2022): 4585. http://dx.doi.org/10.3390/molecules27144585.
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The inorganic selenium is absorbed and utilized inefficiently, and the range between toxicity and demand is narrow, so the application is strictly limited. Selenium nanoparticles have higher bioactivity and biosafety properties, including increased antioxidant and anticancer properties. Thus, producing and applying eco-friendly, non-toxic selenium nanoparticles in feed additives is crucial. Bacillus paralicheniformis Y4 was investigated for its potential ability to produce selenium nanoparticles and the activity of carboxymethyl cellulases. The selenium nanoparticles were characterized using zeta potential analyses, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Additionally, evaluations of the anti-α-glucosidase activity and the antioxidant activity of the selenium nanoparticles and the ethyl acetate extracts of Y4 were conducted. B. paralicheniformis Y4 exhibited high selenite tolerance of 400 mM and the selenium nanoparticles had an average particle size of 80 nm with a zeta potential value of −35.8 mV at a pH of 7.0, suggesting that the particles are relatively stable against aggregation. After 72 h of incubation with 5 mM selenite, B. paralicheniformis Y4 was able to reduce it by 76.4%, yielding red spherical bio-derived selenium nanoparticles and increasing the carboxymethyl cellulase activity by 1.49 times to 8.96 U/mL. For the first time, this study reports that the carboxymethyl cellulase activity of Bacillus paralicheniforis was greatly enhanced by selenite. The results also indicated that B. paralicheniformis Y4 could be capable of ecologically removing selenite from contaminated sites and has great potential for producing selenium nanoparticles as feed additives to enhance the added value of agricultural products.
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Pechová, A., AntošováL, L. Pavlata i A. Podhorský. "Effect of sodium selenite or lactate-protein selenium complex supplementation on selenium status in goat kids". Czech Journal of Animal Science 60, No. 1 (15.07.2016): 16–24. http://dx.doi.org/10.17221/7907-cjas.
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Muthu, Arjun, Daniella Sári, Aya Ferroudj, Hassan El-Ramady, Áron Béni, Khandsuren Badgar i József Prokisch. "Microbial-Based Biotechnology: Production and Evaluation of Selenium-Tellurium Nanoalloys". Applied Sciences 13, nr 21 (26.10.2023): 11733. http://dx.doi.org/10.3390/app132111733.
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Using seleno-compounds and telluric compounds is a practical approach for developing solutions against drug-resistant bacterial infections and malignancies. It will accelerate the search for novel treatments or adjuvants for existing therapies. Selenium and tellurium nanospheres can be produced by lactic acid bacteria. The bacteria can differentiate the selenium and tellurium when the medium contains both selenite and tellurite. Therefore, our question in this study was the following: are they making alloys from the selenium and tellurium and what will be the composition, color, and shape of the nanoparticles? We used a simple microbial synthesis to produce nanoselenium, nanotellurium, and their alloys from sodium selenite and sodium tellurite using Lactobacillus casei. This bacterium produced red spherical amorphous elemental selenium nanospheres with a diameter of 206 ± 33 nm from selenite and amorphous black nanorods with a length of 176 ± 32 nm and a cross-section of 62 ± 13 nm from tellurite. If the initial medium contains a mixture of selenite and tellurite, the resulting nanoparticles will contain selenium and tellurium in the same ratios in the alloy as in the medium. This proves that Lactobacillus casei cannot distinguish between selenite and tellurite. The shape of the nanoparticles varies from spherical to rod-shaped, depending on the ratio of selenium and tellurium. The color of nanomaterials ranges from red to black, depending on the percentage of selenium and tellurium. These nanomaterials could be good candidates in the pharmaceutical industry due to their antipathogenic and anticarcinogenic properties.
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Bébien, Magali, Gilles Lagniel, Jérôme Garin, Danièle Touati, André Verméglio i Jean Labarre. "Involvement of Superoxide Dismutases in the Response of Escherichia coli to Selenium Oxides". Journal of Bacteriology 184, nr 6 (15.03.2002): 1556–64. http://dx.doi.org/10.1128/jb.184.6.1556-1564.2002.
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ABSTRACT Selenium can provoke contrasting effects on living organisms. It is an essential trace element, and low concentrations have beneficial effects, such as the reduction of the incidence of cancer. However, higher concentrations of selenium salts can be toxic and mutagenic. The bases for both toxicity and protection are not clearly understood. To provide insights into these mechanisms, we analyzed the proteomic response of Escherichia coli cells to selenate and selenite treatment under aerobic conditions. We identified 23 proteins induced by both oxides and ca. 20 proteins specifically induced by each oxide. A striking result was the selenite induction of 8 enzymes with antioxidant properties, particularly the manganese and iron superoxide dismutases (SodA and SodB). The selenium inductions of sodA and sodB were controlled by the transcriptional regulators SoxRS and Fur, respectively. Strains with decreased superoxide dismutase activities were severely impaired in selenium oxide tolerance. Pretreatment with a sublethal selenite concentration triggered an adaptive response dependent upon SoxRS, conferring increased selenite tolerance. Altogether, our data indicate that superoxide dismutase activity is essential for the cellular defense against selenium salts, suggesting that superoxide production is a major mechanism of selenium toxicity under aerobic conditions.
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Słupczyńska, Maja, Dorota Jamroz, Janusz Orda, Andrzej Wiliczkiewicz i Barbara Król. "Long-Term Supplementation of Laying Hen Diets with Various Selenium Sources as a Method for the Fortification of Eggs with Selenium". Journal of Chemistry 2018 (13.11.2018): 1–7. http://dx.doi.org/10.1155/2018/7986591.
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The following study focuses on a comparison of the effectiveness of egg content enrichment with selenium (Se) via application of sodium selenite (Na-selenite), selenium-enriched yeast (Se-Yeast), or selenomethionine (Se-Met) in laying hen diets. Two hundred sixteen laying hens were divided into four treatments, each comprising eighteen replications, and each with three hens per cage. Animals were fed a basal diet without Se supplementation (control: selenium content 0.058 mg/kg), with the addition of Na-selenite, Se-Yeast, or Se-Met in amounts equivalent to 0.3 mg/kg of added selenium. The egg quality, the selenium content in eggs after the third and the fifth months of using Se supplementation, and the selenium level in the liver were determined. Enrichment of egg content with selenium was the most effective (382 μg/kg) via application of dietary Se-Met. Application of Na-selenite and Se-Yeast led to a similar effect on Se-accretion in egg content (255.9 and 258.9 μg/kg, respectively). Additionally, the calculated average Se concentration in one fresh egg was also higher in eggs from hens that received selenium additives in their diet and was far higher, almost three times higher for Se-Met addition, than the concentrations in controls. Se-accretion in the liver wet tissue was greater following application of Se-Yeast in the diet than following other treatments. These results indicate that the use of selenomethionine in the laying hen diet is the best method of enriching eggs with this micronutrient. In turn, the eggs obtained in this way can be an excellent source of highly bioavailable selenium in the human diet.
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Xu, Mengmeng, Song Zhu, Lingling Wang, Zhiyi Wei, Liting Zhao, Guiyang Shi i Zhongyang Ding. "Influence of Selenium Biofortification on the Growth and Bioactive Metabolites of Ganoderma lucidum". Foods 10, nr 8 (12.08.2021): 1860. http://dx.doi.org/10.3390/foods10081860.
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Selenium biofortification of edible and medicinal mushrooms is an effective way to produce selenium-enriched food supplements. Ganoderma lucidum is the typical one with excellent biological activity. This study investigated G. lucidum growth and bioactive metabolites alterations during liquid culture with different concentrations of selenite. Low selenium levels did not affect growth and mycelia morphology, whereas high selenium levels negatively influenced growth, dramatically decreased biomass, caused nucleic acid and protein leakage, damaged cell walls and membranes, and resulted in indicators such as degraded cells, a red color, and an unpleasant odor. Through headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis, ten volatile Se compounds were identified in G. lucidum with 200 ppm selenite, which led to an odor change, whereas only three with 50 ppm selenite. SeMet was the major selenoamino acid in the 50 ppm selenite group by high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS), but more MeSeCys was produced with 200 ppm selenite. Polysaccharide yields were promoted and inhibited with 50 and 200 ppm selenite, respectively. These results provide comprehensive insights into the effects of selenite on G. lucidum in liquid culture and are beneficial for functional selenium-enriched mushroom production and improving nutritive values.
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Wolter, B., M. Ellis, F. K. McKeith, K. D. Miller i D. C. Mahan. "Influence of dietary selenium source on growth performance, and carcass and meat quality characteristics in pigs". Canadian Journal of Animal Science 79, nr 1 (1.03.1999): 119–21. http://dx.doi.org/10.4141/a98-028.
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Inorganic (sodium selenite) and organic (selenium-enriched yeast) dietary selenium sources were compared in a performance study using 48 growing–finishing pigs. There was no effect of selenium source on growth and meat-quality traits. The organic selenium source reduced backfat thickness at the last lumbar vertebra, but not at other positions, and increased loin-eye area. Key words: Meat quality, pigs, selenium source
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Suzuki, Kazuo T., Chiaki Doi i Noriyuki Suzuki. "Simultaneous tracing of multiple precursors each labeled with a different homo-elemental isotope by speciation analysis: Distribution and metabolism of four parenteral selenium sources". Pure and Applied Chemistry 80, nr 12 (1.01.2008): 2699–713. http://dx.doi.org/10.1351/pac200880122699.
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The availability, distribution, and metabolism of four typical selenium sources [inorganic selenite and selenate, and organic selenomethionine (SeMet) and methylselenocysteine (MeSeCys)] were compared by administering them simultaneously through a parenteral route. The four selenium sources were each labeled with a different enriched selenium isotope (82Se, 78Se, 77Se, and 76Se, respectively), and administered intravenously at the dose of 25 μg Se/kg body weight each to rats that had been depleted of natural abundance selenium with a single isotope, 80Se, by feeding 80Se-selenite in drinking water and a selenium-deficient diet. At 1 h post-injection, the amounts of the four tracers recovered from major organs and blood comprised around 70, 55, and 50 % of the doses for selenite, MeSeCys and SeMet, and selenate, respectively, being most abundant in the liver. The intact precursors, except for selenite, were recovered from all organs. 77Se and 76Se of SeMet and MeSeCys origin, respectively, were much more efficiently recovered from the pancreas than selenite and selenate, in forms mostly bound to proteins together with intact forms, suggesting that SeMet and MeSeCys are preferentially distributed directly to the pancreas. The incorporations of selenium into selenoprotein P (Sel P) and selenosugars were most efficient from selenite and less efficient from SeMet, suggesting that selenite was most efficiently utilized for the syntheses of selenoproteins and selenosugars. Although selenate was partly excreted into the urine in its intact form, it was retained longer in the plasma in its intact form than the other selenium sources. The advantage of simultaneous administration of multiple precursors each labeled with a different enriched isotope to depleted hosts followed by simultaneous tracing of the labeled isotopes over the conventional method with a single tracer is emphasized together with cautions that may occur with the new multiple tracer method.
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Badgar, Khandsuren, i József Prokisch. "simple method for preparing elemental selenium nano- coating inside a silicone surface". Acta Agraria Debreceniensis, nr 1 (1.06.2021): 35–43. http://dx.doi.org/10.34101/actaagrar/1/8940.
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Selenium nanoparticles (SeNPs) with a bright red colour have aroused worldwide attention due to their unique properties in selenium supplementation because of their low toxicity and favourable bioavailability. A simple method was developed for making a red selenium nanolayer on the inner surface of Polyvinyl chloride (PVC) and silicone tube. The selenium nanoparticles were produced by the reaction of sodium selenite and ascorbic acid. Red amorphous selenium nanoparticles have been successfully synthesized by the reaction of 500 mg dm-3 Se (sodium selenite) solution with 10 g dm-3 ascorbic acid solution at room temperature, and morphology was confirmed by X-ray diffraction analysis (XRD). The coating density was compared on PVC and silicone surfaces by using Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray (EDS) analysis. The nanolayer with about 16 µm thickness on the silicone surface significantly evenly distributed compared to the PVC surface. The selenium coated silicone tube could be a good source of selenium for a continuous, low-level selenium supplementation of farm animals via drinking water.
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Yang, Wenqin, Tingting Jiang, Yaqi Wang, Xiaojing Wang i Rui Wang. "Combined Transcriptomics and Metabolomics Analysis Reveals the Effect of Selenium Fertilization on Lycium barbarum Fruit". Molecules 28, nr 24 (14.12.2023): 8088. http://dx.doi.org/10.3390/molecules28248088.
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As a beneficial nutrient and essential trace element, selenium plays a significant role in plant growth functions and human protein biosynthesis. Plant selenium enrichment is mainly obtained from both natural soil and exogenous selenium supplementation, while human beings consume selenium-enriched foods for the purposes of selenium supplementation. In this study, different types of selenium fertilizers were sprayed onto Lycium barbarum in Ningxia, and transcriptomics and metabolomics techniques were used to explore the effects of selenium on the fruit differentials and differential genes in Lycium barbarum. Taking the “Ning Qiyi No.1” wolfberry as the research object, sodium selenite, nano-selenium, and organic selenium were sprayed at a concentration of 100 mg·L−1 three times from the first fruiting period to the harvesting period, with a control treatment comprising the spraying of clear water. We determined the major metabolites and differential genes of the amino acids and derivatives, flavonoids, and alkaloids in ripe wolfberries. We found that spraying selenium significantly enhanced the Lycium barbarum metabolic differentiators; the most effective spray was the organic selenium, with 129 major metabolic differentiators and 10 common metabolic pathways screened after spraying. Nano-selenium was the next best fertilizer we screened, with 111 major metabolic differentiators, the same number as organic selenium in terms of differential genes and common metabolite pathways. Sodium selenite was the least effective of the three, with only 59 of its major metabolic differentials screened, but its differential genes and metabolites were enriched for five common pathways.
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Sun, Na Xin, Gui Xiang Zhang, Yue Hui Liu i Yuan Xiu Wang. "Optimization of Selenium Yeild by Saccharomyces sp. III Using Statistical Designs". Advanced Materials Research 781-784 (wrzesień 2013): 1278–83. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.1278.
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The objective of the study was to optimize the conditions in a culture medium for the selenium yeild enriched by Saccharomyces sp. III using Plackett-Burman design and Box-Behnken design. The Plackett-Burman multifactorial design was first employed to screen the significant factors in the fermentation for the selenium yeild, and subsequent use of the response surface methodology was further optimized for the selenium yeild by Box-Behnken design. The important factors in the culture medium, identified by the initial screening method of Placket-Burman, were sodium selenite, glucose and the liquid volume. The optimal amounts for maximum selenium yeild were: sodium selenite 15.8 mg/L; glucose 40.2 g/L; the liquid volume 120 mL in 250 mL flask. Using this statistical experimental design, the selenium yeild under optimal condition reached about 1679.32 μg selenium /g dry cell.
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Matvyeyeva, Svetlana. "Influence of compensation of selenium deficiency on immunological parameters of patients with multidrugresistant tuberculosis at the background of subclinical hypothyroidism". Bulletin of the Academy of Sciences of Moldova. Medical Sciences 71, nr 3 (styczeń 2022): 242–44. http://dx.doi.org/10.52692/1857-0011.2021.3-71.20.
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In 60 patients with multidrug-resistant tuberculosis at the background of subclinical hypothyroidism serum level of selenium, thyroid state and immunological parameters were studied in dynamic of the intensive phase of chemotherapy. Initially low level of selenium, subclinical hypothyroidism and weaken immunological response toward tuberculosis were diagnosed. Prescribing of selenite sodium with 200 μ daily during 60 daily doses normalized serum level of selenium, restored thyroid function and improved immunological response. Using of selenite sodium like an accompanying medicine during chemotherapy of multidrug tuberculosis at the background of subclinical hypothyroidism after estimation of serum level of selenium is recommended.
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Neves, Ellen Gaby, Flavia Maria de Moraes Ramos-Perez, Deborah Queiroz Freitas, Frab Norberto Boscolo i Solange Maria Almeida. "Radioprotective Effect of Sodium Selenite on Developing Teeth". Brazilian Dental Journal 24, nr 4 (lipiec 2013): 375–79. http://dx.doi.org/10.1590/0103-6440201302193.
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Radioprotective agents like selenium are used to reduce the damage caused by radiation in healthy tissues. The aim of this study was to evaluate the effect of sodium selenite on the development of the molars of offspring of rats irradiated during odontogenesis. Twenty pregnant rats were randomly divided into 4 groups: control, irradiated, selenium and selenium/irradiated. The selenium and selenium/irradiated groups received 0.3 mg/kg of sodium selenite at 18 days of pregnancy. The rats of the irradiated and selenium/irradiated groups received a single dose of 4 Gy of X rays on the abdominal region at the 19th day of pregnancy. The offspring was sacrificed at 3 and 4 days after birth for evaluation of the birefringence of the enamel organic matrix, and at 30 days for evaluation of the intercuspal dimensions of the molars. The selenium/irradiated group was similar to the irradiated group with respect to the thickness and irregularity of the enamel organic matrix region in the evaluated birefringence, as the intercuspal dimensions of the molars. In conclusion, sodium selenite had no radioprotective action on the development of the molars of offspring of rats irradiated during odontogenesis and had a toxic effect in the initial time.
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Shi, Chen-Yang, Yin-Chin Hew i Choon-Nam Ong. "Inhibition of aflatoxin B1-induced cell injury by selenium: an in vitro study". Human & Experimental Toxicology 14, nr 1 (styczeń 1995): 55–60. http://dx.doi.org/10.1177/096032719501400111.
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Dietary selenium is an essential trace element in human nutrition. Selenium has been shown in animal studies to inhibit aflatoxin hepatocarcinogenesis. However, the cellu lar mechanism responsible for the inhibition has not been thoroughly studied. This study examines the effect of two selenium compounds, namely, sodium selenite and selenium- enriched yeast extract (SeY), on the cytotoxicity, DNA- binding and mutagenicity of aflatoxin B1 (AFB1) in cul tured Chinese hamster ovary (CHO) cells. CHO cells, after treatment with 2 μg ml-1 selenite or 80 μg ml-1 SeY, exhibit ed increased resistance to AFB1-induced cell killing. At a concentration of 50 μg ml-1 AFB1, cell survival, measured by the clonogenicity assay, was increased by 21- and 10- fold in selenite- and SeY-treated cells, respectively. However, selenium treatment did not appear to affect AFB1-DNA binding. Similarly, no effect was observed on AFB1 mutagenicity, as determined by the hypoxanthine- guanine phosphoribosyl transferase (HPRT) gene mutation assay. The results showed that selenium could effectively protect cells from AFB1 cytotoxicity in cultured cells but had no effect on AFB1-DNA adduct formation or mutagen esis. It is suggested that there are multiple pathways of AFB1 toxicity and that selenium can modulate AFB1- induced cell killing independent of its genotoxicity.
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Mladin, Georgiana, Mihaela Ciopec, Adina Negrea, Narcis Duteanu, Petru Negrea, Paula Svera (m. Ianăşi) i Cătălin Ianăşi. "Selenite Removal from Aqueous Solution Using Silica–Iron Oxide Nanocomposite Adsorbents". Gels 9, nr 6 (19.06.2023): 497. http://dx.doi.org/10.3390/gels9060497.
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In recent years, during industrial development, the expanding discharge of harmful metallic ions from different industrial wastes (such as arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, or zinc) into different water bodies has caused serious concern, with one of the problematic elements being represented by selenium (Se) ions. Selenium represents an essential microelement for human life and plays a vital role in human metabolism. In the human body, this element acts as a powerful antioxidant, being able to reduce the risk of the development of some cancers. Selenium is distributed in the environment in the form of selenate (SeO42–) and selenite (SeO32–), which are the result of natural/anthropogenic activities. Experimental data proved that both forms present some toxicity. In this context, in the last decade, only several studies regarding selenium’s removal from aqueous solutions have been conducted. Therefore, in the present study, we aim to use the sol–gel synthesis method to prepare a nanocomposite adsorbent material starting from sodium fluoride, silica, and iron oxide matrices (SiO2/Fe(acac)3/NaF), and to further test it for selenite adsorption. After preparation, the adsorbent material was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The mechanism associated with the selenium adsorption process has been established based on kinetic, thermodynamic, and equilibrium studies. Pseudo second order is the kinetic model that best describes the obtained experimental data. Also, from the intraparticle diffusion study, it was observed that with increasing temperature the value of the diffusion constant, Kdiff, also increases. Sips isotherm was found to best describe the experimental data obtained, the maximum adsorption capacity being ~6.00 mg Se(IV) per g of adsorbent material. From a thermodynamic point of view, parameters such as ΔG0, ΔH0, and ΔS0 were evaluated, proving that the process studied is a physical one.
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Butler, Clive S., Charles M. Debieux, Elizabeth J. Dridge, Peter Splatt i Matthew Wright. "Biomineralization of selenium by the selenate-respiring bacterium Thauera selenatis". Biochemical Society Transactions 40, nr 6 (21.11.2012): 1239–43. http://dx.doi.org/10.1042/bst20120087.
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Bacterial anaerobic respiration using selenium oxyanions as the sole electron acceptor primarily result in the precipitation of selenium biominerals observed as either intracellular or extracellular selenium deposits. Although a better understanding of the enzymology of bacterial selenate reduction is emerging, the processes by which the selenium nanospheres are constructed, and in some cases secreted, has remained poorly studied. Thauera selenatis is a Gram-negative betaproteobacterium that is capable of respiring selenate due to the presence of a periplasmic selenate reductase (SerABC). SerABC is a molybdoenzyme that catalyses the reduction of selenate to selenite by accepting electrons from the Q-pool via a dihaem c-type cytochrome (cytc4). The product selenite is presumed to be reduced in the cytoplasm, forming intracellular selenium nanospheres that are ultimately secreted into the surrounding medium. The secretion of the selenium nanospheres is accompanied by the export of a ~95 kDa protein SefA (selenium factor A). SefA has no cleavable signal peptide, suggesting that it is also exported directly for the cytoplasmic compartment. It has been suggested that SefA functions to stabilize the formation of the selenium nanospheres before secretion, possibly providing reaction sites for selenium nanosphere creation or providing a shell to prevent subsequent selenium aggregation. The present paper draws on our current knowledge of selenate respiration and selenium biomineralization in T. selenatis and other analogous systems, and extends the application of nanoparticle tracking analysis to determine the size distribution profile of the selenium nanospheres secreted.
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Maia, Luisa B., Biplab K. Maiti, Isabel Moura i José J. G. Moura. "Selenium—More than Just a Fortuitous Sulfur Substitute in Redox Biology". Molecules 29, nr 1 (24.12.2023): 120. http://dx.doi.org/10.3390/molecules29010120.
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Living organisms use selenium mainly in the form of selenocysteine in the active site of oxidoreductases. Here, selenium’s unique chemistry is believed to modulate the reaction mechanism and enhance the catalytic efficiency of specific enzymes in ways not achievable with a sulfur-containing cysteine. However, despite the fact that selenium/sulfur have different physicochemical properties, several selenoproteins have fully functional cysteine-containing homologues and some organisms do not use selenocysteine at all. In this review, selected selenocysteine-containing proteins will be discussed to showcase both situations: (i) selenium as an obligatory element for the protein’s physiological function, and (ii) selenium presenting no clear advantage over sulfur (functional proteins with either selenium or sulfur). Selenium’s physiological roles in antioxidant defence (to maintain cellular redox status/hinder oxidative stress), hormone metabolism, DNA synthesis, and repair (maintain genetic stability) will be also highlighted, as well as selenium’s role in human health. Formate dehydrogenases, hydrogenases, glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases will be herein featured.
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Qin, Shun Yi, Fu Chen, Yong Gang Guo, Bao Xia Huang, Jiang Bing Zhang i Ji Fei Ma. "Effects of Nano-Selenium on Kindey Selenium Contents, Glutathione Peroxidase Activities and GPx-1 mRNA Expression in Mice". Advanced Materials Research 1051 (październik 2014): 383–87. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.383.
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The experiment was conducted to evaluate kindey selenium status, glutathione peroxidase (GPx) activity and GPx-1 expression in mice fed with nanoselenium. Sixty KM mice, female and male in half, were randomly divided into control, sodium selenite and nanoselenium groups. 0.5 milliliter of water, sodium selenite (2 μg Se/mL) and nanoselenium (2 μg Se/mL) were respectively supplemented to the three groups in oral (ig) every day. Whole experiment lasted for 28 days. Kindey selenium contents, GPx activities and GPx-1 mRNA expression were analyzed at experiment trrmination. The results showed that kindey selenium contents and GPx activities in nanoselenium group and sodium selenite group were very significantly higher than those in control group (P<0.01); kindey GPx activities in nanoselenium group were significantly higher than that in sodium selenite group (P<0.05). Kindey mRNA expression of GPx-1 was approx 166% higher in nanoselenium group and approx 157% higher in sodium selenite group than that in control group. Kindey mRNA expression of GPx-1 was approx 3.50 % higher in nanoselenium group than that in sodium selenite group. The results indicated that nanoselenium supplementation could significantly enhance kindey selenium contents, GPx activities and GPx-1 mRNA expression in mice, nanoselenium was more available than sodium selenite in increasing kindey selenium contents, GPx activities and GPx-1 mRNA expression in mice.
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Sonet, Jordan, Maurine Mosca, Katarzyna Bierla, Karolina Modzelewska, Anna Flis-Borsuk, Piotr Suchocki, Iza Ksiazek i in. "Selenized Plant Oil Is an Efficient Source of Selenium for Selenoprotein Biosynthesis in Human Cell Lines". Nutrients 11, nr 7 (4.07.2019): 1524. http://dx.doi.org/10.3390/nu11071524.
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Selenium is an essential trace element which is incorporated in the form of a rare amino acid, the selenocysteine, into an important group of proteins, the selenoproteins. Among the twenty-five selenoprotein genes identified to date, several have important cellular functions in antioxidant defense, cell signaling and redox homeostasis. Many selenoproteins are regulated by the availability of selenium which mostly occurs in the form of water-soluble molecules, either organic (selenomethionine, selenocysteine, and selenoproteins) or inorganic (selenate or selenite). Recently, a mixture of selenitriglycerides, obtained by the reaction of selenite with sunflower oil at high temperature, referred to as Selol, was proposed as a novel non-toxic, highly bioavailable and active antioxidant and antineoplastic agent. Free selenite is not present in the final product since the two phases (water soluble and oil) are separated and the residual water-soluble selenite discarded. Here we compare the assimilation of selenium as Selol, selenite and selenate by various cancerous (LNCaP) or immortalized (HEK293 and PNT1A) cell lines. An approach combining analytical chemistry, molecular biology and biochemistry demonstrated that selenium from Selol was efficiently incorporated in selenoproteins in human cell lines, and thus produced the first ever evidence of the bioavailability of selenium from selenized lipids.