Reduced glutathione accelerates the oxidative damage produced by sodium n-propylthiosulfate, one of the causative agents of onion-induced hemolytic anemia in dogs.
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The oxidative effects of sodium n-propylthiosulfate, one of the causative agents of onion-induced hemolytic anemia in dogs, were investigated in vitro using three types of canine erythrocytes, which are differentiated by the concentration of reduced glutathione and the composition of intracellular cations. After incubation with sodium n-propylthiosulfate, the methemoglobin concentration and Heinz body count in all three types of erythrocytes increased and a decrease in the erythrocyte reduced glutathione concentration was then observed. The erythrocytes containing high concentrations of potassium and reduced glutathione (approximately five times the normal values) were more susceptible to oxidative damage by sodium n-propylthiosulfate than were the normal canine erythrocytes. The susceptibility of the erythrocytes containing high potassium and normal reduced glutathione concentrations was intermediate between those of erythrocytes containing high concentrations of potassium and reduced glutathione and normal canine erythrocytes. In addition, the depletion of erythrocyte reduced glutathione by 1-chloro-2, 4-dinitrobenzene resulted in a marked decrease in the oxidative injury induced by sodium n-propylthiosulfate in erythrocytes containing high concentrations of potassium and reduced glutathione. The generation of superoxide in erythrocytes containing high concentrations of potassium and reduced glutathione was 4.1 times higher than that in normal canine erythrocytes when the cells were incubated with sodium n-propylthiosulfate. These observations indicate that erythrocyte reduced glutathione, which is known as an antioxidant, accelerates the oxidative damage produced by sodium n-propylthiosulfate. (+info)
Induction of ascorbate peroxidase by ethylene and hydrogen peroxide during growth of cultured soybean cells.
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In cultured soybean cells, a transient ethylene burst in the pre-stationary phase was followed by an induction of ascorbate peroxidase (AsPOX) in the stationary phase. Treatment of cells with the ethylene antagonist, silver thiosulfate (STS), resulted in the suppression of enzyme activity. Application of the ethylene releasing agent 2-chloroethylphosphonic acid (CEPA) in the medium led to an increased enzyme activity when treated in the pre-stationary phase. On the contrary, a remarkable inhibitory effect on enzyme activity was elicited by 1,3-dimethyl-2-thiourea (DMTU), trapping the hydrogen peroxide generated when treated in the stationary phase. Likewise, a steady level of AsPOX transcript was reduced by STS treatment. Furthermore, its effect appeared to be more rapid and prominent during the pre-stationary phase. It is suggested that the induction of AsPOX in cultured soybean cells during the stationary phase could result, at least in part, by the hydrogen peroxide generated as a result of preceding ethylene production. (+info)
Fusibacter paucivorans gen. nov., sp. nov., an anaerobic, thiosulfate-reducing bacterium from an oil-producing well.
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A strictly anaerobic, halotolerant, spindle-shaped rod, designated strain SEBR 4211T, was isolated from an African saline oil-producing well. Cells stain Gram-positive, which was confirmed by electron microscopy observations. Strain SEBR 4211T was motile by means of one to four peritrichous flagella, had a G+C content of 43 mol% and grew optimally at 37 degrees C, pH 7.3, with 0 to 3% (w/v) NaCl. It utilized a limited number of carbohydrates (cellobiose, glucose, fructose, mannitol and ribose) and produced acetate, butyrate, CO2 and H2 as end products from glucose fermentation. It reduced thiosulfate to sulfide. In the presence of thiosulfate, a decrease in butyrate and an increase in acetate production was observed. Phylogenetically, strain SEBR 4211T was related to members of the low G+C Clostridiales order with Clostridium halophilum as the closest relative (16S rDNA sequence similarity of 90%). On the basis of phenotypic, genotypic and phylogenetic characteristics of the isolate, it is proposed to designate it as a new species of a new genus, Fusibacter gen. nov., as Fusibacter paucivorans sp. nov. The type strain is SEBR 4211T (= DSM 12116T). (+info)
Identification of the yeast mitochondrial transporter for oxaloacetate and sulfate.
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Saccharomyces cerevisiae encodes 35 members of the mitochondrial carrier family, including the OAC protein. The transport specificities of some family members are known, but most are not. The function of the OAC has been revealed by overproduction in Escherichia coli, reconstitution into liposomes, and demonstration that the proteoliposomes transport malonate, oxaloacetate, sulfate, and thiosulfate. Reconstituted OAC catalyzes both unidirectional transport and exchange of substrates. In S. cerevisiae, OAC is in inner mitochondrial membranes, and deletion of its gene greatly reduces transport of oxaloacetate sulfate, thiosulfate, and malonate. Mitochondria from wild-type cells swelled in isoosmotic solutions of ammonium salts of oxaloacetate, sulfate, thiosulfate, and malonate, indicating that these anions are cotransported with protons. Overexpression of OAC in the deletion strain increased greatly the [(35)S]sulfate/sulfate and [(35)S]sulfate/oxaloacetate exchanges in proteoliposomes reconstituted with digitonin extracts of mitochondria. The main physiological role of OAC appears to be to use the proton-motive force to take up into mitochondria oxaloacetate produced from pyruvate by cytoplasmic pyruvate carboxylase. (+info)
Desulfonispora thiosulfatigenes gen. nov., sp. nov., a taurine-fermenting, thiosulfate-producing anaerobic bacterium.
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Strain GKNTAUT has been described as a bacterium able to ferment the organosulfonate taurine (2-aminoethanesulfonate) quantitatively to acetate, ammonia and thiosulfate, an unusual metabolic product. This novel fermentation has now also been observed in four independent isolates from two continents. All five organisms were strictly anaerobic, Gram-positive, motile, spore-forming bacteria. Enrichments with isethionate (2-hydroxyethanesulfonate) and cysteate (2-amino-3-sulfopropionate), in contrast, yielded bacteria that disproportionated the sulfonate to sulfate and sulfide. The phylogenetic location of the taurine fermenters was analysed on the basis of 16S rDNA sequences. Strain GKNTAUT (= DSM 11270T = ATCC 700533T) is described as the type strain of a new genus and species, for which the name Desulfonispora thiosulfatigenes gen. nov., sp. nov. is proposed. (+info)
Sunflower meal as cause of chronic copper poisoning in lambs in southeastern Spain.
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Sunflower meal with a copper/molybdenum ratio of 10 caused copper toxicosis in lambs. Copper must be analyzed on a dry matter basis in liver and renal cortex. Oral administration of molybdenum and thiosulfate had a certain effectiveness in sick animals. Care must be taken with feedstuffs made from copper-dependent plants. (+info)
Characterization of a sulfurtransferase from Arabidopsis thaliana.
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A database search for similarities between sequenced parts of the Arabidopsis thaliana genome with known sulfurtransferase sequences from Escherichia coli and mammals was undertaken to obtain information about plant sulfurtransferase-like proteins. One gene and several homologous EST clones were identified. One of the EST clones was used for screening an Arabidopsis cDNA library. The isolated full-length clone consists of 1134 bp and encodes a 42.6 kDa protein that includes a putative transit peptide sequence of about 7.1 kDa. Sequence comparisons with known sulfurtransferases from different organisms confirmed high homology between them and the existence of several highly conserved regions. Results of a Southern blot performed with genomic Arabidopsis DNA showed the occurrence of at least two sulfurtransferase-like isozymes in Arabidopsis. Recombinant proteins with and without the putative transit peptide were expressed in E. coli with an N-terminal His6-tag, purified by affinity chromatography and tested for enzyme activity using different sulfur donors and acceptors. Both recombinant proteins catalyzed the formation of SCN- from thiosulfate and cyanide as a rhodanese per definition; however, both recombinant proteins preferred 3-mercaptopyruvate to thiosulfate. A monospecific antibody produced by using the mature recombinant protein as an antigen recognized a single protein band in total extracts of Arabidopsis plants equating to the full-length protein size. A single band equating to the size of the mature protein was detected from purified Arabidopsis mitochondria, but there was no antigenic reaction with any protein from chloroplasts. The function of the protein is still speculative. Now tools are available to elucidate the roles and substrates of this sulfurtransferase in higher plants. (+info)
Delayed administration of sodium thiosulfate in animal models reduces platinum ototoxicity without reduction of antitumor activity.
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Platinum-based chemotherapeutic agents, such as carboplatin and cisplatin, are effective against many human tumors, but their use may be limited by a high incidence of ototoxicity. Delayed administration of the chemoprotective agent sodium thiosulfate (STS) reduces the ototoxicity of carboplatin in a guinea-pig model, when given up to 8 h after the chemotherapy, and also reduces hearing loss in patients given carboplatin with osmotic blood-brain barrier opening for treatment of brain tumors. We tested whether STS, given at times that achieved otoprotection, could impact the chemotherapeutic efficacy of carboplatin. The impact of STS was evaluated by measuring the onset of growth of LX-1 human small cell lung carcinoma s.c. xenografts in the nude rat. When STS was administered as two boluses, 2 and 6 h after treatment with carboplatin and etoposide, there was a decrease in the time to tumor progression. In contrast, when STS administration was delayed until 8 h after carboplatin/etoposide, there was no reduction in the antitumor cytotoxicity of the chemotherapy. STS infusion did not significantly affect ultrafilterable platinum pharmacokinetics in the guinea pig. To explore the potential wider applicability of STS, in a pilot study we tested its efficacy against cisplatin ototoxicity. Delayed administration of STS, 2 h after cisplatin, was protective against cisplatin-induced ototoxicity in the guinea pig model, as determined by electrophysiological measures. On the basis of these data, we suggest that delayed administration of STS may provide a mechanism to reduce the ototoxicity caused by administration of carboplatin or cisplatin for both central nervous system and systemic cancer chemotherapy. (+info)