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PubMed2003

Modulation of the arsenic effects on cytotoxicity, viability, and cell cycle in porcine endothelial cells by selenium.

The differential effects of arsenic compounds and the effect of selenium on arsenic-induced changes in cytotoxicity, viability, and cell cycle of porcine aorta endothelial cells (PAECs) were investigated. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay indicated that arsenic trioxide (As(2)O(3)) and sodium arsenite (NaAsO(2)) showed similar cytotoxicity, whereas sodium arsenate (Na(2)HAsO(4)) did not show cytotoxicity in PAECs. As(2)O(3) and NaAsO(2) at 20 microM decreased PAEC viability, decreased G0/G1 phase, and increased apoptosis. An increased G2/M phase was observed in NaAsO(2)-treated PAECs, whereas an increase in secondary necrosis (late apoptosis) was observed in As(2)O(3)-treated PAECs. As(2)O(3)-induced apoptosis was associated with upregulation of p53 and caspase 3, whereas NaAsO(2)-induced apoptosis was associated with p53 upregulation. Sodium selenite (Na(2)SeO(3)) at 1 nM reduced 20 microM As(2)O(3)-induced cytotoxicity, but not apoptosis, at 24 h. Increased glutathione peroxidase (GPX) activity by Na(2)SeO(3) pretreatment in 20 microM As(2)O(3)-treated PAECs suggests that Na(2)SeO(3) modulates As(2)O(3)-induced cytoxicity by GPX modulation.

Animals↗
PubMed2000

Cloning, heterologous expression, and enzymological characterization of human squalene monooxygenase.

The cDNA for human squalene monooxygenase, a key enzyme in the committed pathway for cholesterol biosynthesis, was amplified from a human liver cDNA library and cloned, and the protein was expressed in Escherichia coli and purified. Kinetic analysis of the purified enzyme revealed an apparent K(m) for squalene of 7.7 microM and an apparent k(cat) of 1.1 min(-1). For FAD the apparent K(m) is 0.3 microM, consistent with a loosely bound flavin. The apparent K(m) for NADPH-cytochrome P450 reductase, the requisite electron transfer partner, is 14 nM. The amount of reductase needed for maximal activity is about threefold less than the amount of squalene monooxygenase present in the assay; thus, electron transfer to the monooxygenase is not likely to be rate limiting. Previous reports have implicated inhibition of this enzyme as the cause of a peripheral demyelination seen in weanling rats fed a diet containing tellurium. As no data were available for humans, the ability of a number of tellurium and related elemental compounds to inhibit the recombinant human enzyme was examined. Tellurite, tellurium dioxide, selenite, and selenium dioxide were inhibitory; the tellurium compounds were more potent than the selenium compounds, as indicated by their IC(50) values (17 and 37 microM, respectively). Kinetic analysis of the inhibition by tellurite suggests multiple sites of interaction with the enzyme in a noncompetitive manner with respect to squalene.

Amino Acid Sequence↗
PubMed1983

A serum-free medium for clonal growth and serial subculture of diploid rat liver epithelial cells.

Clonal growth and serial subculture of diploid liver epithelial cells from neonatal rats were achieved in a serum-free medium (SFM) supplemented with linoleic and oleic acid linked to fatty acid-free bovine serum albumin (fafBSA), epidermal growth factor (EGF), transferrin, insulin, selenous acid, and fetuin. Because it is not known whether factors added to defined media facilitate attachment, support proliferation, or both, a serum-free "attachment medium" was first devised in which cells would attach to the substratum without loss of viability. Then a growth medium that would support cell proliferation was developed. Fetuin enhanced the degree of attachment, and the lipid supplements and EGF induced a marked proliferative response. Serum-free medium supported the formation of colonies equivalent in size, number, and morphology to those obtained in serum-supplemented medium. Cells plated at a higher inoculum density and subcultured regularly for up to 25 wk underwent two to three doublings per week and acquired a flattened epithelial cell morphology. Early passages of rat liver epithelial cells, cultured in SFM may be useful in studies of the regulation of cell proliferation and differentiation.

Animals↗
PubMed2001

Protective effects of selenium against mercury toxicity in cultured Atlantic spotted dolphin (Stenella plagiodon) renal cells.

Marine mammals are known for their low susceptibility to mercury toxicity, and selenium may play a role in this protection against mercury intoxication. To gain insight into mechanisms by which selenium might inhibit mercury toxicity in cetacean cells, we investigated the effects of sodium selenite on cell proliferation and cell death (including apoptosis, oncosis, and necrosis) of control and mercuric chloride-treated Atlantic spotted dolphin renal cells (Sp1K cells). Concurrent exposure to 80 microM Na2SeO3 provided full protection against the decrease in cell proliferation induced by 20 microM HgCl2. Pretreatment with Na2SeO3 increased the protective effects of selenium administered later in conjunction with mercury, but pretreatment alone did not provide protection against mercury given alone. Furthermore, Na2SeO3 administered after the exposure to HgCl2 did not protect cells. These data suggest that the coexistence of Na2SeO3 and HgCl2 was essential for the protective effects of Na2SeO3 against the toxicity of HgCl2 in Sp1K cells, and may involve selenium-mercury binding. This is supported by the results of an experiment in which earlier premixed mercury and selenium solutions were less cytotoxic than freshly mixed solutions. Furthermore, HgCl2 induced apoptosis in Sp1K cells, as revealed by nuclear specific dye (7-AAD) incorporation and cell flow cytometry, and this was prevented by the concurrent exposure to Na2SeO3. Inhibition of mercury-induced apoptosis in marine mammal cells, provided by selenium, may contribute to the in vivo protection. This study is the first report that addresses the mechanism of mercury-selenium antagonism in cultured cetacean cells at the cellular level.

Animals↗
PubMed1992

Alpha-(phenylselenenyl)acetophenone derivatives with glutathione peroxidase-like activity. A comparison with ebselen.

Here we describe a new class of organoselenium compounds possessing glutathione peroxidase-like activity. The parent compound, alpha-(phenylselenenyl)acetophenone (PSAP), increased the rate of reaction of glutathione with H2O2, tert-butylhydroperoxide, cumene hydroperoxide, linoleic acid hydroperoxide and dilinoleyl lecithin hydroperoxide by 7.0, 25.1, 34.1, 19.1 and 8.4-fold, respectively, as assessed by the oxidized glutathione (GSSG) reductase enzyme assay. Direct assay of the removal of hydrogen peroxide and glutathione from reaction mixtures confirmed the peroxidase-like activities of these selenoorganic compounds, but indicate that the conventional coupled GSSG reductase assay may be unsuitable for the assessment of the catalytic capacity of PSAP and Ebselen. One possible mechanism of catalysis by PSAP involves an initial oxidation at selenium. Thiol may then react with the selenoxide to yield a selenium (II) compound, H2O and a disulfide. Compounds derived from PSAP may provide potential selenium-based anti-inflammatory agents.

Acetophenones↗
PubMed1990

A retrograde transport method for mapping zinc-containing fiber systems in the brain.

A method for selectively labeling the CNS neurons that give rise to zinc-containing axonal boutons is described. Focal intracerebral infusions of selenium anions are used to produce a precipitate (presumably ZnSe) in zinc-containing axonal boutons at the injection site, and within 24-48 h, the precipitate is transported to the neurons of origin of those boutons. Silver enhancement is used to render the ZnSe visible in sections prepared for the light or electron microscope. No evidence of retrograde labeling is apparent in neurons that do not contain zinc in their boutons. Thus, the method provides a chemically specific technique for retrograde tracing of zinc-containing pathways in the CNS.

Animals↗
PubMed1984

Variation of Se, Zn, Co, Fe and Rb distribution in rats upon sequence of injection with SeO2 and glutathione.

The contents of Se, Zn, Co, Fe and Rb in several organs of Wistar rats were determined by instrumental neutron activation analysis (INAA) after injections of SeO2 and glutathione (GSH). Se was incorporated in all the examined organs, and the efficiency of incorporation does not depend upon the sequence of injection with SeO2 and GSH. The sequence of these injections affects the contents of the other elements in all the examined organs.

Animals↗
PubMedDate not supplied

Synthesis of 2-methoxy and 4-methoxy equine estrogens.

4-Methoxyequilin and 2-methoxyequilin were synthesized from the corresponding 4-bromoequilin and 2-iodoequilin derivatives, respectively, by nucleophilic displacement of halogen with methoxide ion in the presence of copper (II) chloride and 15-crown-5-ether. 4-Bromoequilin was prepared by reacting equilin with one equivalent of N-bromoacetamide. 2-Iodoequilin was prepared by reductive dehalogenation of 2,4-diiodoequilin, which in turn was obtained by treatment of equilin with two equivalents of iodine in methanolic ammonium hydroxide solution. 4-Methoxy-equilenin and 2-methoxyequilenin were prepared from the corresponding 4-iodo- and 2-iodo-7 epsilon, 8 epsilon-epoxyestrone derivatives, respectively. Nucleophilic displacement of iodine with methoxide ion was carried out as described earlier with simultaneous aromatization of the B ring leading to 4- and 2-methoxyequilenin derivatives. Alternatively, 4-methoxyequilenin was obtained from 4-methoxyequilin by selenium dioxide oxidation.

Animals↗
PubMed1985

The effects of dietary L-ascorbic acid on the absorption and utilization of Na75SeO3 of silver-treated rats.

Male hooded lister rats of the Rowett Institute strain, treated with silver in the drinking water, were used to study the effects of L-ascorbic acid on the utilization of Na75SeO3. Silver treatment dramatically decreased the absorption of 75Se from the rat GI tract. An attempt was made to utilize the reducing ability of L-ascorbic acid upon the absorption of 75Se from the rat GI tract. Increasing concentrations of L-ascorbic acid slightly increased the amount of 75Se absorbed from the rat gut.

Animals↗
PubMed1986

Studies on the interaction between SeO2 and sulfur compounds and distribution of Rb, Zn, Co, Fe and Hg in mice by instrumental neutron activation analysis.

Content of Se, Rb, Zn, Co, Fe and Hg in liver, kidneys, spleen, brain and blood of SAS/4 mice were determined after i.p. injection with SeO2, gluthathione, cysteine, cysteamine or methionine. Instrumental neutron activation analysis (INAA) was applied as the analytical method. Se was incorporated in all the examined organs, the the efficiency of the incorporation depended upon the sulfur compounds injected. Injection with above compounds affects the contents of the other elements in all mice organs.

Animals↗
PubMed1995

Use of INAA to study Se, Sb, Zn and Co levels of yeast cells.

Yeast cells, Saccharomyces cerevisiae, were exposed to Sb(V)(10-5M) and SeO2(10-4M) or seleno-cystine (CySe)2(5 x 10-5M). Se, Sb, Zn and Co levels of the yeast were measured by instrumental neutron activation analysis. The results obtained show that in the absence of Se, Sb is taken up by the cells and the highest concentration of Sb in the yeast was observed during the initial 2.5 h of incubation. Both Se-compounds resulted, in general, in a minute decrease of uptake yield of Sb by the cells. This effect can be particularly observed in the presence of SeO2. The presence of Sb in the yeast medium slightly increased the Se level only after long incubation times. Se uptake by the yeast was higher (regardless of Sb dosage) when the yeast was incubated in the medium containing (CySe)2 (in comparison with SeO2). The presence of Se-compounds and/or Sb caused decrease in the levels of Zn found in the cells. While SeO2 presence resulted in minor changes of the Co level of the yeast, the combined presence of Sb and Se-compounds produced the significant enhancement of Co abundance. The similar effect was noted in the yeast incubated in a medium containing only (CySe)2 or Sb.

Antimony↗
PubMed2004

Acute oral selenium intoxication with ten times the lethal dose resulting in deep gastric ulcer.

A 48-year-old woman presented after taking 2000 mg of selenium dioxide, corresponding to 10 times the experimental lethal dose in animals. She presented with mildly altered consciousness and hematemesis. Endoscopy revealed mucosal damage throughout the oral cavity, esophagus, and stomach. There was no evidence of perforation. After intubation and gastric lavage, hemodialysis was performed. The patient was discharged uneventfully on the 16(th) day. This case highlights a very rare acute selenium intoxication. Serum and urinary selenium levels and serum glutathione peroxidase activities during the patient's course were followed, as well as the mucosal corrosive damage caused by the selenium.

Acute Disease↗
PubMed1999

An acute intratracheal selenium study: immediate effects on respiration in guinea pigs.

Pulmonary function was assessed in non-sensitized male guinea pigs (206-445 g) before and after intratracheal (ITr) treatment with saline or selenium (Se, 0.06 mg/100 g body weight) as selenium dioxide (SeO2) or seleno-L-methionine (SeM). Pulmonary functional parameters such as the respiratory rate (f), tidal volume (TV), dynamic lung compliance (Cdynl) and lung resistance (Rl) were determined using the respiratory flow (F) signal and the transpulmonary signal obtained via the intrapleural pressure (P) from the animal. Although, pulmonary dysfunction was observable with exposure to two different Se compounds, the SeO2-induced changes in f and Rl were significant (P < 0.05). Treatment with SeM did not result in alteration of any of the parameters significantly. Results indicated that acute ITr SeO2 exposure affects respiration precipitated by a significantly decreased f and an increased Rl unlike after SeM. The Cdynl did not change significantly after treatment with either of the two Se compounds. Comparing the immediate effects of the two different Se compounds on respiration, acute ITr SeO2 exposure was found to be more detrimental to pulmonary function than SeM.

Animals↗