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PubMed2002

Prostaglandin D synthase in the prenatal ovine brain and effects of its inhibition with selenium chloride on fetal sleep/wake activity in utero.

It has been proposed that prostaglandin (PG) D(2) induces physiological sleep in mammals by acting on sleep centers located in the anterior hypothalamus. In fetal sheep, definitive rapid-eye-movement and non-rapid-eye-movement sleep states appear at approximately 125 d gestation (term is approximately 147 d). In adult animals, PGD synthase (PGDS) (functionally and structurally homologous to beta-trace protein) is secreted into CSF with a circadian pattern, with the highest concentrations present during sleep. In this study we show that PGDS/beta-trace protein is present in fetal sheep CSF at 125 and 135 d gestation but not at 90 d gestation. SeCl(4), a specific inhibitor of PGDS, was given to unanesthetized fetal sheep (130-140 d gestation) by intracerebroventricular infusion at a dose of 25, 100, 500, or 1000 pmol/min for 4 hr. Artificial CSF was infused in control experiments. Arousal behavior, defined as the presence of nuchal muscle electromyogram activity, electro-ocular activity, and breathing movements during low-amplitude electrocortical activity, increased from 3.8 +/- 1 min/hr to 6.6 +/- 0.5 and 7.0 +/- 0.3 min/hr at doses of 100 and 500 pmol/min, respectively (p < 0.05). SeCl(4) at 25 and 1000 pmol/min had no significant effect on arousal activity. Infusion of PGD(2) at 500 pmol/min intracerebroventricularly for 4 hr decreased the incidence of arousal from 3.8 +/- 0.5 min/hr to 0.7 +/- 0.3 min/hr (p < 0.05). When 500 pmol/min PGD(2) was infused immediately after a 4 hr infusion of SeCl(4) (500 pmol/min), the SeCl(4)-induced increase in arousal behavior was abolished. Together, the presence of PGDS/beta-trace protein in fetal CSF in late gestation and the effects of SeCl(4) in increasing the incidence of arousal-like behavior suggest that PGD(2) has a role in the induction and maintenance of prenatal sleep.

Animals↗
PubMed1999

The distribution of zinc selenite and expression of metallothionein-III mRNA in the spinal cord and dorsal root ganglia of the rat suggest a role for zinc in sensory transmission.

Zinc appears to play a role in synaptic transmission in the hippocampus. We tested the hypothesis that zinc is similarly involved in sensory transmission by determining whether vesicular zinc and metallothionein-III (MT-III), a zinc-binding protein, are localized in rat primary afferent neurons. MT-III mRNA, measured using RT-PCR, and MT-III immunoreactivity, were both present in the spinal cord as well as the thoracic and lumbar dorsal root ganglia (DRG). At a time (24 hr) that allows retrograde transport of zinc selenite to cell bodies, only small-diameter neurons and neurons scattered throughout lamina V of the spinal cord were stained by sodium selenite injected intrathecally. This stain disappeared if a ligature was placed on the dorsal root to block axonal transport, demonstrating that these cells are, in fact, zinc-containing primary afferent neurons. When assessed 1 hr after sodium selenite, stain was distributed throughout the neuropil of the spinal cord, especially in lamina III and the area surrounding the central canal. Even in rhizotomized animals, large- and small-diameter DRG neuronal cell bodies were also stained with either selenite (1 hr) or 6-methoxy 8-para-toluene sulfonamide quinoline (TSQ). Paradoxically, this unique pool of zinc was eliminated in large-diameter DRG neurons after neonatal capsaicin treatment, which had no effect on selenite stain or MT-III mRNA content in small-diameter DRG neurons. In summary, we demonstrate that there is a population of capsaicin-insensitive small-diameter primary afferent neurons that are zinc-containing. In addition, there is a unique pool of capsaicin-sensitive zinc that is associated with large-diameter cell bodies.

Animals↗
PubMed1999

Fetal mouse selenophosphate synthetase 2 (SPS2): biological activities of mutant forms in Escherichia coli.

A novel gene, sps2, detected in mouse embryo at the early stages of development has been identified as an analog of the E. coli selenophosphate synthetase gene. Unlike the E. coli enzyme, the presence of selenocysteine in the mouse enzyme is indicated by a TGA codon in the open reading frame of the cDNA. Using an N-FLAG monoclonal antibody, it was shown that the full length N-FLAG-sps2 gene product was expressed in COS-7 cells. To investigate the biological activity of the sps2 gene product in vivo, the mutated sps2 gene, which contains cysteine in the place of the TGA encoded selenocysteine in the wild type, was expressed in the E. coli selD deficient mutant, MB08. Like the E. coli wild type selD gene, the mutant sps2 gene complemented the selD mutation. However, replacement of Cys with either Ala, Ser, or Thr resulted in a loss of ability to complement the selD mutation. The SPS2-CYS protein expressed in E. coli was purified and its catalytic activity was determined. The Km value for ATP was 0.75 mM and Vmax was 9.23 nmole/min/mg protein. These results confirm that the mouse embryonic sps2 gene encodes an eukaryotic selenophosphate synthetase, and that availability of selenophosphate as a selenium donor compound is widespread.

Adenosine Triphosphate↗
PubMed1999

Quantitative significance of measuring trimethylselenonium in urine for assessing chronically high intakes of selenium in human subjects.

The purpose of the present study was to investigate the effects of Se restriction on the excretion of Se in men who had consumed high levels of this element during their entire lives. With the use of stable isotopes of Se as selenite, the excretion of methylated Se in urine was investigated in Chinese men (n 10) who had habitual chronic high intakes of this element. The relationship between either urine Se or trimethylselenonium (TMSe) to the estimated long-term Se intake was not linear over the entire range of intake, which was also true for the infusion of labelled selenite. A non-linear relationship was also found between urine TMSe and urine Se both for TMSe arising from catabolism of endogenous body Se and that from infused selenite. The data suggest a close precursor-product relationship of urine Se and its TMSe component based on the nearly identical specific activities for these two selenocompounds. Although dimethylselenide in breath was not measured in the present study, combining urinary TMSe with this breath test may be more useful in the assessment of long-term Se status.

Adult↗
PubMed1997

[Mineral medicinal material cinnabar in Hunan Province].

Presenting the distribution characteristics and formation types of the mineral medicinal material cinnabar in Hunan Province, this paper expounds in detail the mineralogical features of the material through chemical analysis, X ray diffraction analysis etc.

Conservation of Natural Resources↗
PubMed2000

Effects of vitamin E and selenium supplementation on esophageal adenocarcinogenesis in a surgical model with rats.

Two well-known antioxidative nutrients, vitamin E and selenium, were used in this study to investigate possible inhibitory action against the formation of esophageal adenocarcinoma (EAC) in rats. In this model, carcinogenesis is believed to be driven by oxidative stress. Male Sprague-Dawley rats (8 weeks old) were divided into four groups and received esophagoduodenal anastomosis (EDA) surgery plus iron supplementation (12 mg/kg/week). Vitamin E and selenium were supplemented in the diet in the forms of alpha-tocopheryl acetate (750 IU/kg) and sodium selenate (1.7 mg Se/kg), which were 10 times the regular amounts in the basic AIN93M diet. At 40 weeks after surgery, all the EDA groups had lower body weights than the non-operated control group. Iron nutrition (hemoglobin, total serum iron and transferrin saturation) was normal as a result of iron supplementation after EDA. Vitamin E supplementation maintained the normal plasma level of alpha-tocopherol in EDA rats, but not those of gamma-tocopherol and retinol. Selenium supplementation increased the serum and liver selenium contents of the EDA rats. Histopathological analysis showed that selenium supplementation increased the incidence of EAC and the tumor volume. The selenium level in the tumor is higher than that in the duodenum of the same animal. Vitamin E supplementation, however, inhibited carcinogenesis, especially in the selenium-supplemented group. We believe that vitamin E exerts its effect through its antioxidative properties, and a high dose of inorganic selenium may promote carcinogenesis by enhancing oxidative stress.

Absorption↗
PubMed2000

Localization of selenium deposits in meristematic cells of Allium sativum L. roots treated with selenium salts.

Ultrastructural analysis of garlic roots treated for 24 h with sodium selenate or sodium selenite at the concentrations 80, 160, 320 microM revealed the presence of selenium deposits in meristematic cells. They appeared as small and large granules or aggregates of electron-dense material. Many small granules were localised in plastids but some in mitochondria, endoplasmic reticulum as well as in Golgi apparatus, nucleus and cytoplasm. Sometimes the large granules were seen in cytoplasm but aggregates of electron-dense material only in vacuoles. It seems possible that these deposits represent a non-dissolved form of selenium, i.e. elemental selenium or its complexes with other ions.

Absorption↗
PubMed2001

Effects of sulfate on the acute toxicity of selenate to freshwater organisms.

This study evaluated the relationship between ambient sulfate concentrations and acute selenate toxicity to freshwater aquatic life. Previous studies indicated that increasing sulfate concentrations reduced selenate bioconcentration and toxicity. However, these studies generally were not conducted in a manner that was conducive to their use in deriving a water quality criterion. We compiled results from previous studies and generated additional data to help define a selenate-sulfate relationship for acute toxicity. Selenate toxicity was determined in standardized test waters with varying sulfate concentrations using Ceriodaphnia dubia, Gammarus pseudolimnaeus, Hyalella azteca, and Pimephales promelas as the test organisms. Analysis of test results indicated that a significant relationship does exist between acute selenate toxicity and ambient sulfate concentrations. Data from these tests and previous studies were combined to develop a statistical relationship sufficiently robust to derive a sulfate-dependent water quality criterion for selenate. The relationship is similar to those commonly derived between divalent metals and hardness to adjust water quality criteria.

Animals↗
PubMed1993

Preliminary observations on the effects of selenate on the development of the embryonic skate, Raja eglanteria.

Morphogenesis of the clearnose skate, Raja eglanteria, was not significantly inhibited as a result of 7 days of exposure to 1-2 mM selenate in the sea water during Days 59-69 of embryonic development (hatching would normally have occurred at 82 +/- 4 days of incubation). Although corneal transparency appeared normal in the eye, preliminary measurements of the thickness of Bowman's layer of the cornea suggested that it was significantly thinner in the corneas of embryos exposed to 1-2 mM selenate. Selenate is an ion reported to inhibit sulfation of glycosaminoglycans in connective tissue.

Animals↗
PubMed1993

Preliminary observations on the effects of selenate on the development of the embryonic skate, Raja eglanteria.

Morphogenesis of the clearnose skate, Raja eglanteria, was not significantly inhibited as a result of 7 days of exposure to 1-2 mM selenate in the sea water during Days 59-69 of embryonic development (hatching would normally have occurred at 82 +/- 4 days of incubation). Although corneal transparency appeared normal in the eye, preliminary measurements of the thickness of Bowman's layer of the cornea suggested that it was significantly thinner in the corneas of embryos exposed to 1-2 mM selenate. Selenate is an ion reported to inhibit sulfation of glycosaminoglycans in connective tissue.

Animals↗
PubMed2001

Uptake and translocation of selenium by maize (Zea mays) from its environmentaly important forms.

Pot culture studies were conducted to examine the effect of selenite (SeO3(2-)) and selenate (SeO4(2-)) on the uptake and translocation of root absorbed selenium in maize Zea mays plants grown in sand and soil culture. Increasing selenium supplementation (0.5-6.00 microg/ml), increased the selenium retention in roots, but there was little transfer of selenium from shoot to grains. The study indicates that selenite species (less mobile) also accumulates in maize plants when supplied in solution form. Selenium does not cause any adverse effect on the maize plants (dry matter yield vs concentration, no significant correlation, p>0.05).

Biological Availability↗
PubMedDate not supplied

[Comparative evaluation of antioxidant properties of neoselen and berberin in chronic heliotrinal hepatitis].

Prominent features of heliotrin-related chronic toxical disorders of the liver developing in hepatic cirrohosis include hyperfermentemia, hypoproteinemia, intensification of lipid peroxidation (LPO), as evidenced by decrease in the activity of the antioxidant defence. In chronic active liver disorders, hyperfermentemia and hyperlipoperoxidation are common, but it is later in the course of the experiment that hypoproteinemia and hypoalbuminemia and manifest depression of the antioxidant defence that come to be developing. Berberin experimental pharmacotherapy has been shown to attenuate the degree of hyperfermentemia, hyperlipoperoxidation and to increase levels of albumin and antioxidant defence enzymes, particularly so earlier in the course of the studies conducted but with aggravation of the pathological process the efficacy of the drug tended to be lower. Neoselen appeared to be effective in alleviating the cytologic syndrome, hyperlipoperoxidation, increasing the activity of the antioxidant defence enzymes. Patients are found to derive more benefit from neoselen therapy with prolongation of its use.

Animals↗
PubMed2003

Variations in color.

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Administration, Cutaneous↗
PubMed2003

Effect of sub-chronic selenium toxicosis on lipid peroxidation, glutathione redox cycle and antioxidant enzymes in calves.

The present investigation reports the effect of sodium selenite-induced sub-chronic toxicity in crossbred cow calves on various antioxidant enzymes. Sodium selenite (0.25 mg/kg for 16 w) resulted in characteristic signs of sub-chronic selenosis, ie alopecia, cracking and enlargement of hooves, interdigital lesions, ring formation on the coronet region, and gangrene at tip of the tail. The sodium selenite resulted in significant rise of blood selenium levels and concurrent increase in erythrocytic glutathione peroxidase (GPx) activity. Blood selenium levels and GPx activity had a high positive correlation (r = 0.97). Blood glutathione levels were lowered from 211.1 +/- 13.4 to 95.56 +/- 11.8 microg/ml. Selenosis caused oxidative stress as evidenced by a 3-fold increase in lipid peroxidation: activities of glutathione-S-transferase, glutathione reductase, superoxide dismutase and catalase were significantly increased. These findings support the hypothesis that the pro-oxidant attributes of selenium play important roles in its toxicity.

Administration, Oral↗
PubMed2001

[Direct determination of impurity elements in antimony products with ICP-AES].

The direct determination of As, Cu, Fe, Pb and Se in antimony products with ICP-AES is presented. We selected compromise condition to determine of As, Cu, Fe, Pb and Se and the influence of matrix concentration is discussed. The detection limits are 0.028-0.327 microgram.mL-1 and the rates of recovery are 94.0%-107.1% and RSD are less than 5%.

Antimony↗
PubMed2001

[Determination of Se, Fe, Si in electrolytic manganese metal by ICP-AES].

The method was established for the simultaneous determination of Se, Fe and Si in electrolytic manganese metal by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sample was dissolved by light sulphuric acid. The analysis conditions were obtained by studying dissolved acid, Mn matrix and background. The recommended method not only proved to be simple and rapid but showed satisfying precision and accuracy as well. The relative standard deviation is less than 2.68% and the recovery is 98%-105%. The t-test showed that no conspicuous difference with typical methods was found.

Electrolysis↗