Effect of Organic Selenium on the Homeostasis of Trace Elements, Lipid Peroxidation, and mRNA Expression of Antioxidant Proteins in Mouse Organs.

(1) In this study we determined the effect of long-term selenomethionine administration on the oxidative stress level and changes in antioxidant protein/enzyme activity; mRNA expression; and the levels of iron, zinc, and copper. (2) Experiments were performed on 4-6-week-old BALB/c mice, which were given selenomethionine (0.4 mg Se/kg b.w.) solution for 8 weeks. The element concentration was determined via inductively coupled plasma mass spectrometry. mRNA expression of SelenoP, Cat, and Sod1 was quantified using real-time quantitative reverse transcription. Malondialdehyde content and catalase activity were determined spectrophotometrically. (3) After long-term SeMet administration, the amount of Se increased by 12-fold in mouse blood, 15-fold in the liver, and 42-fold in the brain, as compared to that in the control. Exposure to SeMet decreased amounts of Fe and Cu in blood, but increased Fe and Zn levels in the liver and increased the levels of all examined elements in the brain. Se increased malondialdehyde content in the blood and brain but decreased it in liver. SeMet administration increased the mRNA expression of selenoprotein P, dismutase, and catalase, but decreased catalase activity in brain and liver. (4) Eight-week-long selenomethionine consumption elevated Se levels in the blood, liver, and especially in the brain and disturbed the homeostasis of Fe, Zn, and Cu. Moreover, Se induced lipid peroxidation in the blood and brain, but not in the liver. In response to SeMet exposure, significant up-regulation of the mRNA expression of catalase, superoxide dismutase 1, and selenoprotein P in the brain, and especially in the liver, was determined.

Effect of Selenium on the Iron Homeostasis and Oxidative Damage in Brain and Liver of Mice.

Selenium is an essential trace element that maintains normal brain function, mainly due its antioxidant properties. Although the amount of Se in the body is tightly regulated by the liver, both an excess of and deficiency in Se can modulate the cellular redox status and affect the homeostasis of other essential elements for both humans and animals. The aim of this study was to determine the effect of inorganic selenium excess on oxidative stress and iron homeostasis in brain and liver of laboratory BALB/c mice, which were supplemented with Na2SeO3 solution (0.2 mg and 0.4 mg Se/kg body weight) for 8 weeks. The content of the lipid peroxidation product malondialdehyde and antioxidant enzyme catalase activity/gene expression were used as markers of oxidative damage and were evaluated by spectrophotometric assays. Selenium and iron concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS). Catalase gene expression was analyzed by qRT-PCR and ΔΔCt methods. Our results showed that doses of 0.2 mg Se and 0.4 mg Se caused a relatively low accumulation of Se in the brain of mice; however, it induced a 10-fold increase in its accumulation in the liver and also increased iron accumulation in both tested organs. Both doses of Se increased the content of malondialdehyde as well as decreased catalase activity in the liver, while the 0.4 mg Se dose has also activated catalase gene expression. Brain of mice exposed to 0.2 mg Se showed reduced lipid peroxidation; however, the exposure to 0.4 mg of Se increased the catalase activity as well as gene expression. One may conclude that exposure to both doses of Se caused the accumulation of this micronutrient in mice brain and liver and have also provided a disrupting effect on the levels of iron. Both doses of Se have triggered oxidative liver damage. In the brain, the effect of Se was dose dependent, where -0.2 mg of Se provided antioxidant activity, which was observed through a decrease in lipid peroxidation. On the contrary, the 0.4 mg dose increased brain catalase activity as well as gene expression, which may have contributed to maintaining brain lipid peroxidation at the control level.

Post-exposure distribution of selenium and aluminum ions and their effects on superoxide dismutase activity in mouse brain.

The study was conducted to determine how aluminum (Al) and selenium (Se) ions alone and in combination affect superoxide dismutase (SOD) activity and to evaluate the distribution of these elements in the blood and the brain of laboratory mice. SOD activity in mouse brain was evaluated after single-time (within 24 h) and repeated (over 14 days) intraperitoneal (IP) injections of SeO32-, Al3+, and (SeO32-+Al3+) solutions. The control mice received IP injections of the same volume of saline. Aluminum concentration in mouse blood increased both after single-time and repeated injections of AlCl3 and the combined (AlCl3 + Na2SeO3) solutions. The concentration of Se increased in blood after single-time and repeated injections of Na2SeO3 and the combined (AlCl3 + Na2SeO3) solutions. After the single-time injection of the experimental solutions, the concentrations of both Al and Se in mouse brain remained at baseline, but after repeated injections of (AlCl3 + Na2SeO3) solutions increased aluminum concentration. A single IP injection of Al did not change SOD activity in mouse brain, while a single injection of Se or the Se + Al mixture decreased it. After 14 days, IP injections of Al or Se alone did not affect SOD activity, while their combination decreased it. Our results showed that Se ions decreased SOD activity in mouse brain after both single-time and repeated IP injections of selenium-containing solutions. The study failed to show a direct or linear effect of increased Al or Se concentrations on SOD activity in mouse brain.

Long-term stability of oxidative stress biomarkers in human serum.

The storage time and storage temperature might affect stability of oxidative stress biomarkers, therefore, they have to be analyzed after long-term storage of serum samples. The stability of three biomarkers reflecting oxidative stress: reactive oxygen metabolites (ROM) for hydroperoxides, total thiol levels (TTL) for the redox status and biological antioxidant potency (BAP) for the antioxidant status, was investigated at several time points during 60 months of storage at -20 and -80 °C. Biomarkers ROM and BAP showed a very good stability during storage for 60 months at both temperatures. In addition, the correlation of the data after 60 months of storage compared with the starting data was very good with correlation coefficients >0.9. The TTL assay showed good results in serum samples stored at -80 °C, but not in samples stored at -20 °C. Serum samples for analysis of the set of oxidative stress biomarkers ROM, BAP and TTL can be stored up to 60 months at -80 °C. ROM and BAP can also be stored at -20 °C during this period. The present results are very important for the biomarker-related epidemiological studies that make use of biobanks with samples stored for many years and for new project planning, including sample storage conditions.

Tissue-Specific Effects of Vitamin E Supplementation.

A multivitamin and mineral supplementation study of 6 weeks was conducted with male and female mice. The control group received a standard dose of vitamins and minerals of 1× the Recommended Daily Intake (RDI), whereas a second group received 3× RDI. A third group received a high dose of vitamin E (25× RDI), close to the upper limit of toxicity (UL), but still recommended and considered to be harmless and beneficial. The high dose of vitamin E caused a number of beneficial, but also adverse effects. Different biomarkers of tissue toxicity, oxidative stress related processes and inflammation were determined. These biomarkers did not change in plasma and erythrocytes to a large extent. In the liver of male mice, some beneficial effects were observed by a lower concentration of several biomarkers of inflammation. However, in the kidney of male mice, a number of biomarkers increased substantially with the higher dose of vitamin E, indicating tissue toxicity and an increased level of inflammation. Since this dose of vitamin E, which is lower than the UL, cause some adverse effects, even after a short exposure period, further studies are required to reconsider the UL for vitamin E.

Long-term stability of cancer biomarkers in human serum: biomarkers of oxidative stress and redox status, homocysteine, CRP and the enzymes ALT and GGT.

AIM: Five frequently used biomarkers in cancer research and epidemiological studies were tested for their assay stability upon storage of serum for 12 months at -20 and -70/-80°C. MATERIALS & METHODS: The biomarker assays include reactive oxygen metabolites (ROM), the total thiol levels (TTL), homocysteine (HCy), C-reactive protein (HS-CRP) and two liver enzymes, alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT). RESULTS: The assays for ROM, HCy, HS-CRP and GGT were stable in human serum samples at the two temperatures tested. The two other assays TTL and ALT, however, showed statistically significant differences in their stability between -20 and -80°C. CONCLUSION: Therefore, storage at -80°C is advised to maintain a reliable assay outcome when serum samples have to be stored for longer periods.

Selective induction of IL-6 by aluminum-induced oxidative stress can be prevented by selenium.

In this study the acute toxic effects of aluminum (Al) on mice have been investigated, including the interactions of Al and selenium (Se). Focus was put on the systemic effects of (co)exposure to Al and Se as a reflection of the redox status in the liver, kidney and brain. Short-term exposure (16 h) to Al resulted in an increase in the systemic inflammation parameters IL-6 and PAI-1, whereas serum levels of TNF-α remained unaffected. The different response pattern of IL-6 and TNF-α probably indicates an increased intracellular oxidative stress and altered redox status in the liver, because the selective increase in IL-6 serves as a protective intrahepatocellular process driven by oxidative stress. The intracellular glutathione concentration GSHtot decreased significantly upon Al exposure. Both the increase in IL-6 and decrease in glutathione status could be prevented by co-exposure to Se, but not the increase in PAI-1. The redox status of the kidney and brain was not markedly affected. Therefore it was concluded that short-term exposure to Al causes adverse effects on the intracellular oxidative stress processes in the liver, as reflected by the selective increase in the IL-6 concentration. This process can be restored by co-administration of the trace element Se as a part of the glutathione redox system.

Protective effect of selenium on aluminium-induced oxidative stress in mouse liver in vivo.

The aim of the study was to evaluate possible protective effects of selenium (Se) against systemic aluminium (Al) toxicity and the redox status of mouse liver after short-term (16 h) exposure to Al in vivo. BALB/c mice were injected i.p. with AlCl(3) (25mg Al(3+) per kg of body mass) or/and Na(2)SeO(3) (1.25mg Se per kg of body mass). The 4-fold increased activity of ALT in serum showed systemic hepatotoxicity that Se could not prevent by competitive mechanisms. The protective effects of Se could only be observed on intracellular oxidative stress events as determined by glutathione status. Exposure to Al leads to the decrease in the total glutathione (GSH(tot)) and GSH/GSSG redox ratio to about 50% of the control. Upon co-exposure to Se+Al, the concentration of GSH(tot) and the redox ratio was restored to the control values. Our results indicate that Se did not have a protective effect on Al-linked liver toxicity, but did ameliorate intracellular oxidative stress processes mediated by glutathione.

Effect of anoxia and Polyscias filicifolia Bailey biomass tincture on the activity of tRNA and aminoacyl-tRNA synthetases in isolated pig heart.

OBJECTIVE: The aim of this study was to investigate effect of anoxia and Polyscias filicifolia Bailey biomass tincture on the activities of different tRNA and aminoacyl-tRNA synthetases in isolated pig heart. MATERIAL AND METHODS: The isolated pig heart was perfused according to the modified method of Langendorf, using an artificial blood circulation apparatus. Anoxia 20 min in duration was performed by perfusion of isolated heart with Krebs-Henseleit bicarbonate buffer saturated with gas mixture (95% N(2) and 5% CO(2)). Control heart was perfused with the same buffer saturated with gas mixture (95% O(2) and 5% CO(2)). Effect of Polyscias filicifolia Bailey biomass tincture was evaluated by perfusion of isolated heart with a buffer containing tincture. Total tRNA and aminoacyl-tRNA synthetases were isolated from pig heart. Activities of tRNA and aminoacyl-tRNA synthetases were measured by the aminoacylation reaction using C(14)-amino acids. RESULTS: Anoxia 20 min in duration has caused a decrease in the acceptor activity of tRNA and increase in the activities of aminacyl-tRNA synthetases. Polyscias filicifolia Bailey tincture did not affect the acceptor activity of tRNA and activities aminacyl-tRNA synthetases. After 20-min anoxic perfusion with the buffer containing Polyscias filicifolia Bailey biomass tincture, the acceptor activities of tRNA increased to the control value and activities of aminacyl-tRNA synthetases reached the control value. CONCLUSIONS: The acceptor activity of tRNA from isolated pig heart decreased and activities of aminacyl-tRNA synthetases increased under anoxia. Perfusion with buffer containing tincture of Polyscias filicifolia Bailey biomass restored acceptor activities of tRNA and activities of aminacyl-tRNA synthetases.

The effects of zinc ions on activities of tRNALeu and leucyl-tRNA synthetase of mice liver.

UNLABELLED: The aim of this study was to examine the effects of zinc ions on activities of tRNA(Leu) and leucyl-tRNA synthetase of mice liver. MATERIAL AND METHODS: White laboratory mice (20-25 g) were used for study purposes. Animals were intoxicated with ions of zinc by injection of 0.15 LD50 dose of zinc sulphate solution (1.56 mg Zn2+ per 1 kg of body weight) into abdominal cavity. After 8 hours, preparations of total tRNA and aminoacyl-tRNA synthetases were isolated from the intoxicated and normal (control) mice liver. Acceptor activity of tRNA(Leu) and activity of leucyl-tRNA synthetase were determined in tRNA aminoacylation reaction using [14C]-labeled leucine. Actions of zinc ions on acceptor activity of tRNA(Leu) and on activity of leucyl-tRNA synthetase from liver of control animals in vitro were determined after addition into reaction mixture different concentrations of zinc sulphate solution. RESULTS: It was determined that acceptor activity of mice liver tRNA( Leu)8 hours after intoxication with zinc ions has increased by 29% and activity of leucyl-tRNA synthetase has increased by 20% as compared to control. Experiments in vitro have shown that 5-20 microM concentrations of zinc ions in reaction mixture stimulate the acceptor activity of mice liver tRNA(Leu)by 18-30%, higher concentration of zinc ions (40 microM)--suppresses it by 26%. The study of leucyl-tRNA synthetase activity in vitro has shown that 5-10 microM concentrations of zinc ions in reaction mixture increase activity of this enzyme by 11-16%, higher concentrations of zinc ions (20-40 microM)--decrease it by 13-21%. CONCLUSIONS: After 8-hour intoxication with zinc ions the activities of both studied components of the translation machinery--tRNA(Leu) and leucyl-tRNA synthetase were increased. It may be connected with the stimulation of zinc-binding metallothionein synthesis which is involved in the detoxification of heavy metals. Low concentrations of zinc ions in reaction mixture increase tRNA(Leu) and leucyl-tRNA synthetase activities; higher concentrations of these ions decrease activity of those components of protein synthesis system. The results show that zinc ions directly act on the activities of both components of translation machinery.

Effect of Polyscias filicifolia Bailey biomass on protein synthesis process in isolated pig heart.

OBJECTIVE: The aim of this study was to investigate effect of Polyscias filicifolia Bailey biomass on protein synthesis process in normoxic and anoxic pig heart. MATERIAL AND METHODS: Experiments were done on isolated pig hearts weighing 100-150 g. Effects of anoxia were evaluated after 20 and 90 min of anoxic perfusion. Control hearts were perfused under aerobic conditions. Investigating action of Polyscias filicifolia Bailey, pig heart was perfused under normoxic and anoxic condition with buffer, which contains tincture Polyscias filicifolia Bailey. For the determination of protein synthesis rate (time of incubation was 15 min) and level (time of incubation was 60 min), incorporation of [14C]-leucine into translational products in a cell-free system was measured. RESULTS: Protein synthesis rate and level in cell-free system decreased by 30% and 20% respectively after 20 min anoxic perfusion and by 48% and 45% respectively after 90 min anoxic perfusion in comparison to the control. Polyscias filicifolia Bailey tincture did not affect the protein synthesis rate and level in cell-free translation system from control pig heart. Polyscias filicifolia Bailey tincture has protective effect on protein synthesis system from pig hearts after 20 min and 90 min anoxic perfusion. Protein synthesis rate and level after 20 min anoxic perfusion with Polyscias filicifolia Bailey tincture was the same as at a control level. However, after 90 min anoxic perfusion with Polyscias filicifolia Bailey tincture protein synthesis rate and level did not reach control level and represented 81% and 76% respectively of control values. Spectrum of newly synthesized polypeptides in cell-free protein synthesis system under anoxic conditions and after treatment with Polyscias filicifolia Bailey tincture did not differ. CONCLUSIONS: Protein synthesis rate and level decreased under long and short-term anoxia. Polyscias filicifolia Bailey biomass restore protein synthesis system under anoxia. Neither anoxia, nor Polyscias filicifolia Bailey tincture did not influence spectrum of newly synthesized proteins.

[Effects of lead ions on activities of tRNALeu and leucyl-tRNA synthetase of mouse liver]. / Svino jonu poveikis peliu kepenu tRNRLeu ir leucil-tRNR-sintetazes aktyvumui.

UNLABELLED: The objective of this study was to examine effect of lead ions on activities of mice liver tRNA(Leu) and leucyl-tRNA synthetase. MATERIAL AND METHODS: For researching white non-breed laboratory mice (20-25 g) were used. Intoxication with ions of lead was performed by injection of sublethal dose of lead acetate solution (50 mg ions of lead per 1 kg of body weight) into abdominal cavity of laboratory animals. Eight hours after intoxication from intoxicated and normal (control) mice liver preparations of tRNA and aminoacyl-tRNA synthetases were isolated. Acceptor activity of tRNA(Leu) and activity of leucyl-tRNA synthetase were determined in tRNA aminoacylation reaction using [(14)C]-labeled leucine. Actions of lead ions on acceptor activity of tRNA(Leu) and on activity of leucyl-tRNA synthetase from liver of control animals in vitro were determined after addition into reaction mixture different concentrations of lead acetate solution. RESULTS: It was determined that acceptor activity of mice liver tRNA(Leu) 8 h after intoxication with lead ions was reduced by 37 percent and activity of leucyl-tRNA synthetase was increased by 22 percent as compared to control. Experiments in vitro have shown that 10 micro M concentration of lead ions in reaction mixture stimulate acceptor activity of mice liver tRNA(Leu) by 17 percent, higher concentrations of lead ions (30-60 microM)--suppress it by 9-80 percent. The study of leucyl-tRNA synthetase activity in vitro has shown that 30 microM concentration of lead ions in reaction mixture increases activity of this enzyme by 16 percent, higher concentrations of lead ions (40-60 microM)--decrease by 17-23 percent. CONCLUSIONS: After 8 h intoxication with lead ions acceptor activity of tRNA(Leu) was decreased and activity of leucyl-tRNA synthetase was increased. It may be part of the compensatory mechanism of the cell to keep synthesis of proteins at the normal level under extreme conditions. Low concentrations of lead ions in reaction mixture increase tRNA(Leu) and leucyl-tRNA synthetase activities, higher concentrations of these ions decrease activity of those components of protein synthesis system. The results show that ions of lead directly suppress activity of both components of translation machinery.

[Effects of aluminum ions on the mouse protein synthesis in vivo and in vitro]. / Aliuminio jonu itaka peles baltymu sintezei in vivo ir in vitro.

Impact of aluminium ions on the translation process in mice liver, kidney, skeletal muscle and heart was investigated in vivo as well as on the protein synthesis in liver cell-free translation system in vitro. We find that at early stages of intoxication the effect of aluminium ions on protein synthesis in muscle tissues differs qualitatively from that one in liver or kidneys. Most noticeable aluminium-induced changes of protein synthesis in organs in vivo occur within the first 15-20 h after intoxication. We show that aluminium ions activates protein synthesis in liver and kidneys (at 8-16 h) while in skeletal muscle and heart does not. These results indirectly are supported by the data of experiments in vitro, which demonstrate that at low concentration aluminium ions activates protein synthesis in the cell-free translation system prepared from liver.