Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THIONEINE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1986

Mercury-binding proteins from the marine mussel, Mytilus edulis.

The marine mussel, Mytilus edulis, possesses low molecular weight, metal-binding proteins which can be induced by and, in turn, bind mercury when individuals are exposed to low, but elevated concentrations of mercury as HgCl2. Induction of the proteins by exposure of mussels to copper, cadmium, or mercury is associated with enhanced tolerance to mercury toxicity. Mercury-binding proteins isolated from gills of mussels occur as two molecular weight variants of about 20-25 and 10-12 kdaltons, respectively, on Sephadex G-75. These have been designated as HgBP20 and HgBP10 following the nomenclature used for cadmium-binding proteins. HgBP20 represents the primary mercury-binding species. These exist as dimers which can be dissociated into subunits by treatment with 1% 2-mercaptoethanol. Further purification of HgBP20 by DEAE-cellulose ion-exchange chromatography resulted in the resolution of three major mercury-binding protein peaks; analysis of two of these showed that both had similar amino acid compositions with 26% half-cystine, 16% glycine, and very low levels of the aromatic amino acids phenylalanine and tyrosine (0.3-0.5%), histidine (0.4%), methionine (about 0.5%), and leucine (about 1%). These are similar to the compositions of proteins reported as mussel thioneins by others. Separation of HgBP20 by anion-exchange high-performance liquid chromatography resulted in the resolution of six peaks, indicating a more complex situation than was evident from DEAE-cellulose separations. Although not completely purified, these also contain cysteine- and glycine-rich proteins.

Amino Acids↗
PubMed2000

Effect of arsenic trioxide on metallothionein and its conversion to different arsenic metabolites in hen liver.

The metabolism of arsenic, its affinity to metallothionein (MT), its influence on selenium levels, and its biotransformation to different metabolites in the liver tissue of laying hens exposed to arsenic trioxide (As2O3) was investigated. The experiment was performed with two groups of hens fed for 19 d with either a standard diet or with the same diet enriched in arsenic (30 microg/g). The major findings were as follows: 1. After 19 d exposure, about 65% of the total liver As was found in the water-soluble phase (100,000g centrifuged supernatant). In liver supernatant, As binding was found mostly in the range of very low-molecular-weight proteins (Mr < 10,000). Although after exposure the amount of MT-like proteins increased, the As bound to it was only in trace amounts. The protein was identified by convential procedures as Zn,Cu-thionein with traces of selenium and arsenic. 2. Arsenic exposure resulted in almost unchanged Se levels regarding its tissue concentrations and distribution between supernatant and pellet, where about 10% of total Se was found in the supernatant. On the contrary, As exposure did affect Cd levels. Tissue Cd concentration was slightly diminished, but the percentage of tissue Cd found in the water-soluble phase was increased from 20% to 40%. 3. In methanol extracts of tissue and supernatant of the As-exposed group, only two arsenic compounds were detected, As(III) and dimethylarsinic acid (DMA), the latter prevailing.

Animals↗
PubMedDate not supplied

Metallothionein levels in the bivalves Callista chione and Venus verrucosa from two Mediterranean sites.

Metallothioneins levels (MTs) in the clams Callista chione and Venus verrucosa, collected from two coastal sites in Greece, were determined and quantified by SDS polyacrylamide gel electrophoresis (SDS-PAGE) and a spectrophotometric assay (Ellman's reaction). SDS-PAGE separation in the digestive gland, which represents the hepato-pancreas in clams, demonstrated the presence of MTs similar to mammalian MT (rabbit liver Cd, Zn-thionein). No other SH-containing proteins apart from the MTs were detected. MT levels quantified by the Ellman's reaction indicated seasonal variation for both species. The highest values were recorded in the spring and the lowest in the autumn. The seasonal variation and the differences in the MT levels of the two areas seem to be related to the reproductive cycle of the organisms as well as to abiotic factors of each area. Our results show that both C. chione and V. verrucosa have the potential to be used as biomarkers of metal pollution, provided that the influence of the external factors is safely quantified.

Animals↗
PubMed1986

A rapid silver-free method for staining the myenteric plexus.

A method is presented for the relatively rapid demonstration of the myenteric plexus. Saturated Sudan black B in 70% ethanol followed by 0.01% aqueous buffered thionein were used on intestinal peels (whole-mounts) to stain myelinated and unmyelinated fibers and neuron cell bodies, respectively. In contrast to accepted silver methods, these two kinds of fibers were distinguished clearly; Schwann cell nuclei and nodes of Ranvier were visible. Preparations had the following attributes: relatively low optical density coupled with high visual contrast, freedom from metallic "mirroring," low background staining of subjacent muscle fibers, and presentation of a polychromatic picture. The entire procedure was under the complete and repeatable control of the operator. Perikaryon and nuclear morphology were clearly demonstrated. The limitations of this method are that it does not provide good visualization of individual unmyelinated neuronal processes and does not permit preparation of permanent slides.

Animals↗
PubMed1996

The role of iron-sulfur clusters in in vivo hydroxyl radical production.

The in vivo production of HO- requires iron ions, H2O2 and O2- or other oxidants but probably does not occur through the Haber-Weiss reaction. Instead oxidants, such as O2-, increase free iron by releasing Fe(II) from the iron-sulfur clusters of dehydratases and by interfering with the iron-sulfur clusters reassembly. Fe(II) then reduces H2O2, and in turn Fe(III) and the oxidized cluster are re-reduced by cellular reductants such as NADPH and glutathione. In this way, SOD cooperates with cellular reductants in keeping the iron-sulfur clusters intact and the rate of HO. production to a minimum. O2- and other oxidants can release iron from Fe(II)-containing enzymes as well as copper from thionein. The released Fe(III) and Cu(II) are then reduced to Fe(II) and Cu(I) and can then participate in the Fenton reaction. In mammalian cells oxidants are able to convert cytosolic aconitase into active IRE-BP, which increases the "free" iron concentration intracellularly both by decreasing the biosynthesis of ferritin and increasing biosynthesis of transferrin receptors. The biological role of the soxRS regulon of Escherichia coli, which is involved in the adaptation toward oxidative stress, is presumably to counteract the oxidative inactivation of the iron clusters and the subsequent release of iron with consequent increased rate of production of HO.

Escherichia coli↗
PubMed1992

Zinc status in proliferative response of T lymphocytes.

The in vitro proliferation of T lymphocytes are highly susceptible to Zn deprivation and Cd addition. In order to define Zn status in T cell proliferation, toxicological and biochemical situation of Zn in proliferative response of T cells was investigated by use of mouse spleen cell cultures stimulated by T cell-mitogen, Con A. The inhibitory effect of Cd on T cell proliferation was protected specifically by Zn. The protection by Zn was effective when Zn was added within 16 h after Con A stimulation. Zn addition affected neither Cd content in cells nor induction of Cd-thionein. These findings indicate that Zn-dependent processes expressed before the S phase of cell cycle are critical for T cell proliferation and are targets susceptible to Cd. Moreover, electrophoretical analysis showed two unknown Zn-binding proteins (49 and 100 KD) induced in spleen cells incubated with Con A and radioactive Zn. These Zn-binding proteins may be associated with the Zn-dependent processes critical for T cell proliferation.

Animals↗
PubMed1982

Binding metal elements in metallothionein fraction from liver of rat injected various metals.

Six elements, Cd, Co, Cu, Mn, Se and Zn, in the metallothionein fractions from liver of rat injected various metals (Cd, Co, Cu, Hg, Se and Zn) were analyzed by neutron activation analysis and were investigated metal binding of it. The concentrations of Cd and Zn were increased by administration of Cd and those of Co and Se were also increased by administration of the each element. On the contrary, the concentration of Cd and Cu were decreased by administration of Se. It may be considered that Co and Se are attached to metallothionein, if its protein is present and the presence of Se influence the binding of Cu and Cd to metallothionein, further it also influence Cd-thionein production.

Animals↗
PubMed1992

Detection by HPLC-ICP of metallothionein in serum of an epileptic child with valproate-associated hepatotoxicity.

A patient who developed valproate-associated hepatotoxicity had significantly lower serum levels of total protein, albumin and selenium than the controls. This study shows that with the beginning of the hepatic coma metallothionein (MT) appeared in the serum mainly in the form of Zn-thionein, which altered the Zn distribution pattern of the serum in a characteristic manner. HPLC-ICP3 was successfully applied to the simultaneous speciation of elements and characterization of MT by the use of one gel permeation column.

Blood Proteins↗
PubMed1991

Testosterone effects on staining density and autoradiographic investigations of the alpha 2-adrenergic receptor in the medial preoptic nucleus of the Japanese quail: relationship to the activation of reproductive behavior.

The effects of gonadectomy combined or not with testosterone (T) therapy on the sexual behavior, cloacal gland area, staining density and alpha 2-adrenergic receptors in the medial preoptic nucleus (POM) were studied in male and female Japanese quail. In castrated males, T increased the cloacal gland size and activated copulatory behavior. In agreement with previous reports, these effects were sexually differentiated: under the influence of T, cloacal gland growth was smaller and this treatment did not activate masculine sexual behavior in females. The optical density of the medial preoptic nucleus stained with thionein blue (Nissl stain) was decreased by castration and increased by T in both males and females. This suggests that T has a profound effect on the synthesis of proteins in the POM and, since POM is a critical site in the activation by T of masculine sexual behavior, these induced proteins are, in all probability, a part of the causal chain of biochemical events giving rise to copulatory behavior. The treatment with T had, by contrast, no clear effect on the number of binding sites and on the affinity of the alpha 2-adrenergic receptors in the POM. Therefore, if the noradrenergic transmission is involved in the induction by T of copulatory behavior, it is probably acting either through the alteration of another adrenergic receptor subtype or through the modulation of the baseline levels or turnover of the transmitter itself.

Animals↗
PubMed1991

Hepatic and renal metallothionein induction in the rat and mouse after treatment with furosemide.

Induction of hepatic and and renal metallothionein by furosemide was studied in the rat and mouse. Treatment of mice with 200 and 300 mg/kg furosemide elevated hepatic metallothionein by 117% and 366%, while renal metallothionein was induced by 29% and 380%, respectively. In the rat the drug was less potent i.e. liver metallothionein was increased by 167% and 217% following injection of 300 and 400 mg/kg furosemide, respectively, whereas kidney was not significantly changed by this treatment. The mouse hepatic and renal metallothionein was identified as zinc-containing thionein by Sephadex G-75 gel filtration (Ve/Vo = 2.0). In both species maximal induction was observed 24 hours post exposure. However, the mouse hepatic and renal metallothionein content declined after additional 24 hours whereas the rat metalloprotein was not reduced even after 72 hours of treatment. It is suggested that alterations in metal homeostasis may be responsible for hepatic and renal metallothionein induction caused by furosemide.

Animals↗
PubMed1990

Reconstitution of Cu,Zn-superoxide dismutase by the Cu(I).glutathione complex.

The reconstitution of Cu,Zn-superoxide dismutase from the copper-free protein by the Cu(I).GSH complex was monitored by: (a) EPR and optical spectroscopy upon reoxidation of the enzyme-bound copper; (b) NMR spectroscopy following the broadening of the resonances of the Cu(I).GSH complex after addition of Cu-free,Zn-superoxide dismutase; and (c) NMR spectroscopy of the Cu-free,Co(II) enzyme following the appearance of the isotropically shifted resonances of the Cu(I), Co enzyme, Cu(I).GSH was found to be a very stable complex in the presence of oxygen and a more efficient copper donor to the copper-free enzyme than other low molecular weight Cu(II) complexes. In particular, 100% reconstitution was obtained with stoichiometric copper at any GSH:copper ratio between 2 and 500. Evidence was obtained for the occurrence of a Cu(I).GSH.protein intermediate in the reconstitution process. In view of the inability of copper-thionein to reconstitute Cu,Zn-superoxide dismutase and of the detection of copper.GSH complexes in copper-over-loaded hepatoma cells (Freedman, J.H., Ciriolo, M.R., and Peisach, J. (1989) J. Biol. Chem. 264, 5598-5605), Cu(I).GSH is proposed as a likely candidate for copper donation to Cu-free,Zn-superoxide dismutase in vivo.

Animals↗
PubMed1990

Copper uptake in wild type and copper metallothionein-deficient Saccharomyces cerevisiae. Kinetics and mechanism.

The mechanism of copper uptake in Saccharomyces cerevisiae has been investigated using a combination of 64Cu2+ and atomic absorption spectrophotometry. A wild type copper-resistant CUP 1R-containing strain and a strain carrying a deletion of the CUP1 locus (yeast copper metallothionein) exhibited quantitatively similar saturable energy-dependent 64Cu2+ uptake when cultures were pregrown in copper-free media (medium [Cu] approximately 15 nM). The kinetic constants for uptake by the wild type strain were Vmax = 0.21 nmol of copper/min/mg of protein and Km = 4.4 microM. This accumulation of 64Cu2+ represented net uptake as confirmed by atomic absorption spectrophotometry. This uptake was not seen in glucose-starved cells, but was supported in glycerol- and ethanol-grown ones. Uptake was inhibited by both N3- and dinitrophenol and was barely detectable in cultures at 4 degrees C. When present at 50 microM, Zn2+ and Ni2+ inhibited by 50% indicating that this uptake process was relatively selective for Cu2+. 64Cu2+ accumulation was qualitatively and quantitatively different in cultures either grown in or preincubated with cold Cu2+. Either treatment resulted in the appearance of a fast phase (t 1/2 approximately 1 min) of 64Cu2+ accumulation which represented isotopic exchange since it did not lead to an increase in the mass of cell-associated copper; also, it was not energy-dependent. Exchange of 64Cu2+ into this pool was not inhibited by Zn2+. Pretreatment with Cu2+ caused a change in the rate of net accumulation as well; a 3-h incubation of cells in 5 microM medium Cu2+ caused a 1.6-fold increase in the velocity of energy-dependent uptake. Prior addition of cycloheximide abolished this Cu2(+)-dependent increase and, in fact, inhibited the 64Cu2+ uptake velocity by greater than 85%. The exchangeable pool was also absent in cycloheximide, Cu2(+)-treated cells suggesting that exchangeable Cu2+ derived from the copper taken up initially by the energy-dependent process. The thionein deletion mutant was similar to wild type in response to medium Cu2+ and cycloheximide indicating that copper metallothionein is not directly involved in Cu2+ uptake (as distinct from retention) in yeast.

Azides↗
PubMed1990

Quantitative DNA patterns in human preneoplastic breast lesions.

In 12 cases of human mammary carcinoma in which a preneoplastic atypical ductal hyperplasia was also identified, quantitative DNA (QDNA) measurements of thionein-stained samples from both lesions were performed using the Cell Image Analysis 100 system. The QDNA values in the preneoplastic and neoplastic lesions from each case showed concordance (six as euploid and six as aneuploid/hyperdiploid). Such congruence suggests a stable inheritance of the somatic mutation(s) that is involved in carcinogenesis and that affects ploidy. If this relationship between concurrent preneoplasia and neoplasia in the ipsilateral breast is confirmed, it offers the possibilities of (1) identifying individuals at risk for developing neoplasias with defined biologic characteristics and (2) developing therapeutic regimens more appropriate to the risk assessment of each patient. It may be possible to conceive of a rational preventive regimen for cancer of the breast.

Breast↗
PubMed1986

[Copper-binding proteins in liver, kidney and brain tissue from a Wilson's disease patient].

Copper-binding proteins (Cu-PBs) in the liver, kidney, and brain tissues from a Wilson's disease patient, who was 19-year-old woman and died of hemolytic crisis, were examined with Sephadex G-75 gel chromatography and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Copper contents, which were determined by flameless atomic absorption spectrophotometry in the liver, kidney, and cerebral tissues from the patient, were 28-, 38-, and 3.5-fold, respectively, as compared to those of control subject, who was 5-year-old girl and died of cerebral palsy. Each tissue was homogenized in 3 volumes of 50 mM Tris-HCl buffer, pH 8.6, and the homogenate was centrifuged at 105,000 g for 60 min to obtain cytosol fraction. Sephadex G-75 gel chromatography of cytosols from Wilson's liver and kidney showed that most of increased copper existed as Cu-thionein (Cu-Th), in contrast to a much lower Cu-Th level in control liver cytosol and to no detectable amount of Cu-Th in control kidney cytosol. In addition, Zn-Th was also increased in Wilson's kidney cytosol, while it was decreased in Wilson's liver cytosol. Gel chromatography of Wilson's cerebral cytosol revealed that the increased copper bound mainly to two proteins with apparent molecular mass of 10 kDa (Cu-BP 1) and 20 kDa (Cu-BP 2), respectively, both of which showed no absorption at 280 nm and were not observed in control cerebral cytosol even after addition of excess copper (50 micrograms/ml) as CuSO4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Role of metallothioneins in disease.

Metallothioneins are small proteins (6,000 to 10,000 mw) with similar amino acid compositions, high content of sulfhydryl amino acids and no aromatic amino acids. Emax at 250 nm is due to cadmium mercaptide bond. Synthesis is induced by a number of metals including zinc, cadmium, mercury, copper, bismuth, gold and silver. These proteins function as a mechanism of intracellular storage of some essential metals such as zinc and copper. Binding of potentially toxic metals like cadmium may be protective; but with saturation of protein by metal, toxicity may occur. Excessive cadmium-thionein may have a role in the pathogenesis of cadmium induced kidney disease. A more sensitive method for detection adn measurement of this protein will greatly enhance future studies, particularly the potential for clinical application.

Animals↗
PubMed1984

Kidney and liver metallothioneins in rats after administration of an organic compound.

Intubation of rats with alpha-mercapto-beta-(2-furyl)-acrylic acid (MFA) for 5 days at 50 mg/kg caused a 7-fold increase in kidney copper concentration, a 2-fold increase in kidney zinc concentration, and a 20% increase in liver zinc concentration. The proteins which bound the increased metals were purified and identified as metallothioneins by their amino acid compositions. Two isoforms were isolated from each organ. Renal thioneins appeared identical to counterpart hepatic apoproteins, but the former bound Cu and Zn in a 2:1 mole ratio and the latter bound only Zn. Kidney contained over 10 times more metallothionein per g of tissue than did liver. In rats previously administered MFA, injection of cadmium sulfate resulted in rapid displacement of liver metallothionein-bound Zn by Cd under conditions where minimal metallothionein was found in Cd-dosed animals not administered MFA. We conclude that MFA induces metallothionein biosynthesis in kidney and liver of normal rats; this is a novel effect for an organic compound.

Acrylates↗
PubMedDate not supplied

Cadmium nephropathy.

Cadmium, an important environmental toxic agent has the kidney as its most important target organ. It is concentrated mainly in the renal cortex. Excessive renal accumulation of cadmium causes well defined morphological and ultrastructural pathological changes in the proximal tubules. Functional changes accompanying cadmium nephropathy include proteinuria, enzymuria, aminoaciduria, glycosuria, polyuria, hepercalciuria, increased urinary uric acid, and cadmium. The observed proteinuria has two components: low molecular weight proteinuria of tubular origin (excess excretion of proteins such as B2-microglobulin) and high molecular weight proteinuria of glomerular origin, (excretion of proteins such as albumin, IgG, transferrin, etc.) The proposed mechanisms of cadmium nephropathy are reviewed. The involvement of metallothionein in cadmium nephropathy and the nephrotoxic effects of cadmium-thionein are discussed.

Animals↗
PubMed1994

Purification and characterization of Ag,Zn-superoxide dismutase from Saccharomyces cerevisiae exposed to silver.

Cu,Zn-superoxide dismutase plays an important role in protecting cells from oxygen toxicity by catalyzing the dismutation of superoxide anion into hydrogen peroxide and oxygen. In Saccharomyces cerevisiae Cu,Zn-superoxide dismutase is coregulated with copper-thionein by copper via the transcription factor ACE 1. We demonstrate here that presence of AgNO3 in the culture medium leads to a five times increase of Cu,Zn-superoxide dismutase mRNA, with a concomitant six times decrease of the enzyme activity. Susceptibility of yeast to silver was apparently inversely related to Cu,Zn-superoxide dismutase activity. From silver-treated yeast a Cu,Zn-superoxide dismutase with impaired dismutase function was purified and was shown to contain silver, which was located to the copper site. These data suggest that Cu,Zn-superoxide dismutase may play an additional direct role in the defense of S. cerevisiae against metal stress by functioning as metal chelator.

Cell Division↗