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PubMed2001

Multicenter study of the frequency of contact allergy to gold.

Gold sodium thiosulfate (GSTS) is reputed to be the most reliable gold antigen, but control studies are still required. Although Koreans have more varied sources of contact with gold, such as herbal medicines with gold coatings and indwelling gold acupuncture needles, no epidemiological studies have been performed. This study examined the frequency and sources of contact allergy to gold in South Korea by a multicenter study. Patch testing with 0.5% GSTS in pet. was conducted in 255 eczema patients and 58 control subjects. Results were observed at 21 days (D) to ensure there were no undetected late reactions in 54 observed patients and 47 controls. 8 (3.1%) of the 255 patients reacted positively to GSTS, including 1 with a late reaction. 1 of the 58 controls showed a positive reaction to GSTS on D4 with a negative reaction on D14. Clinical relevance was lacking in the patients with positive reactions. Unexpectedly, the above particular sources of gold contact gave rise to few allergic reactions in our patients.

Adolescent↗

PubMed2003

Azotobacter vinelandii rhodanese: selenium loading and ion interaction studies.

Rhodanese is a sulfurtransferase which in vitro catalyzes the transfer of a sulfane sulfur from thiosulfate to cyanide. Ionic interactions of the prokaryotic rhodanese-like protein from Azotobacter vinelandii were studied by fluorescence and NMR spectroscopy. The catalytic Cys230 residue of the enzyme was selectively labelled using [15N]Cys, and changes in 1H and 15N NMR resonances on addition of different ions were monitored. The results clearly indicate that the sulfur transfer is due to a specific reaction of the persulfurated Cys residue with a sulfur acceptor such as cyanide and not to the presence of the anions. Moreover, the 1H-NMR spectrum of a defined spectral region is indicative of the status of the enzyme and can be used to directly monitor sulfur loading even at low concentrations. Selenium loading by the addition of selenodiglutathione was monitored by fluorescence and NMR spectroscopy. It was found to involve a specific interaction between the selenodiglutathione and the catalytic cysteine residue of the enzyme. These results indicate that rhodanese-like proteins may function in the delivery of reactive selenium in vivo.

Azotobacter vinelandii↗

PubMed2004

Localization, purification and properties of a tetrathionate hydrolase from Acidithiobacillus caldus.

The moderately thermophilic bacterium Acidithiobacillus caldus is found in bacterial populations in many bioleaching operations throughout the world. This bacterium oxidizes elemental sulfur and other reduced inorganic sulfur compounds as the sole source of energy. The purpose of this study was to purify and characterize the tetrathionate hydrolase of A. caldus. The enzyme was purified 16.7-fold by one step chromatography using a SP Sepharose column. The purified enzyme resolved into a single band in 10% polyacrylamide gel, both under denaturing and native conditions. Its homogeneity was confirmed by N-terminal amino acid sequencing. Tetrathionate hydrolase was shown to be a homodimer with a molecular mass of 103 kDa (composed from two 52 kDa monomers). The purified enzyme had optimum activity at pH 3.0 and 40 degrees C and an isoelectric point of 9.8. The periplasmic localization of the enzyme was determined by differential fractionation of A. caldus cells. Detected products of the tetrathionate hydrolase reaction were thiosulfate and pentathionate as confirmed by RP-HPLC analysis. The activity of the purified enzyme was drastically enhanced by divalent metal ions.

Acidithiobacillus↗

PubMed1999

Intraarterial chemotherapy as neoadjuvant treatment of oral cancer.

Neoadjuvant chemotherapy in patients with primary squamous cell carcinomas of the oral cavity should lead to high remission rates whilst having low morbidity. Efficacy can also be enhanced by treating small tumour stages. As part of a multi-modality therapy of all stages of primary oral cavity carcinoma, 103 patients were treated with neoadjuvant intraarterial (i.a.) chemotherapy. After regimen A with 100 mg/m2 i.a. cisplatin followed by 5 day continuous intravenous infusion of 5-fluorouracil (1 g/m2 per day) in 36 patients, an i.a. high pressure chemo-perfusion with a dose of 150 mg/m2 cisplatin was used with simultaneous intravenous infusion of 9 g/m2 sodium thiosulfate (regimen B, 67 patients). Subsequent treatment comprised radical surgery and simultaneous radiochemotherapy with docetaxel. Partial and complete remissions were found in 80.6% (regimen A) and 67.2% (regimen B) of cases, tumour growth was inhibited in 11.1% and 31.3%. Very low toxicity could be shown especially in regimen B. 66.7% and 74.6% of patients could be operated on radically. Survival rate was 61.1% (regimen A, 22.7 months of mean observation time) and 79.1% (regimen B, 8.4 months). Patients with high-grade remissions seemed to have a survival advantage. Neoadjuvant i.a. chemotherapy with cisplatin, especially in its high dose variant, is a practical therapeutic tool for the treatment of all stages of primary oral cavity carcinoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

[Extravasation of chemotherapeutic agents: prevention and therapy].

Based on the potential to cause local tissue injury drugs are classified as vesicant, irritant and non-irritant. The frequency of extravasation is considered to be between 0.6 % and 6 %. More frequently an inflammatory reaction is caused by thrombophlebitis or a local hypersensitivity reaction following chemotherapy administration rather than by an extravasation. A number of factors are known to increase the risk of extravasation. By the consideration of these risk factors preventive guidelines for the safe administration of chemotherapeutic agents have been published. Central venous devices significantly reduce the risk of extravasation. To date there are no generally approved treatment guidelines for the management of extravasations. Treatment is mostly empirical. Nevertheless some general measures are to be recommended: Firstly, aspiration of the extravasated fluids should be attempted. Furthermore local supportive care such as intermittent topical warming or cooling is at least palliative and to a certain degree reduces the extent of the injury. Beside these non pharmacological therapies the beneficial effects of Dimethylsulfoxid (DMSO) -- or Hyaluronidase-administration dependent on the type of paravasation have been proven. The use of sodium bicarbonate, sodium thiosulfate or corticosteroids is no longer recommended. In the case of extravasation rapid and correct management is crucial for the benefit of any treatment. Therefore, written guidelines for both the handling of cytotoxic agents and also the management of an extravasation should be present in all Departments where cytotoxic agents are administered. In addition to these guidelines an extravasation kit including all necessary materials and drugs to treat extravasations should be available.

Antineoplastic Agents↗

PubMed2002

An effective method of inactivating chlorhexidine.

OBJECTIVE: The purpose of this study was to find an effective inactivating agent for chlorhexidine that would facilitate removal of all residual antimicrobial effect, which may cause false-negative results during microbiologic culturing. STUDY DESIGN: L-alpha-lecithin, Tween 80, and sodium thiosulfate were used in different proportions to prepare 6 potential inactivating solutions. Nine mL of each inactivating solution was mixed with 1 mL of 2% chlorhexidine solution. After 5 minutes of equilibration, 0.1 mL of bacterial cell suspension containing 2 x 10(4) viable cell of Enterococcus faecalis was added to the mixture. At 10 and 60 minutes, 0.1-mL aliquots were withdrawn and spread over blood agar plates and incubated at 37 degrees C for 72 hours. The number of colony-forming units on the blood agar plates was determined and recorded. RESULTS: The combination of 3% Tween 80 and 0.3% L-alpha-lecithin was found to be the most effective inactivating agent, allowing full recovery of the test organisms in the presence of chlorhexidine. CONCLUSION: The present study demonstrated a method to predictably inactivate chlorhexidine.

Anti-Infective Agents, Local↗

PubMed2004

Evidence for the physiological role of a rhodanese-like protein for the biosynthesis of the molybdenum cofactor in humans.

Recent studies have identified the human genes involved in the biosynthesis of the molybdenum cofactor. The human MOCS3 protein contains an N-terminal domain similar to the Escherichia coli MoeB protein and a C-terminal segment displaying similarities to the sulfurtransferase rhodanese. The MOCS3 protein is believed to catalyze both the adenylation and the subsequent generation of a thiocarboxylate group at the C terminus of the smaller subunit of molybdopterin (MPT) synthase. The MOCS3 rhodanese-like domain (MOCS3-RLD) was purified after heterologous expression in E. coli and was shown to catalyze the transfer of sulfur from thiosulfate to cyanide. In a defined in vitro system for the generation of MPT from precursor Z, the sulfurated form of MOCS3-RLD was able to provide the sulfur for the thiocarboxylation of MOCS2A, the small MPT synthase subunit in humans. Mutation of the putative persulfide-forming active-site cysteine residue C412 abolished the sulfurtransferase activity of MOCS3-RLD completely, showing the importance of this cysteine residue for catalysis. In contrast to other mammalian rhodaneses, which are mostly localized within mitochondria, MOCS3 in addition to the subunits of MPT synthase are localized in the cytosol.

Base Sequence↗

PubMed2000

Productive and nonproductive intermediates in the folding of denatured rhodanese.

The competition between protein aggregation and folding has been investigated using rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) as a model. During folding from a urea-denatured state, rhodanese rapidly forms associated species or intermediates, some of which are large and/or sticky. The early removal of such particles by filtration results in a decreased refolding yield. With time, a portion of the smaller aggregates can partition back first to intermediates and then to refolded protein, while a fraction of these irreversibly form unproductive higher aggregates. Dynamic light scattering measurements indicate that the average sizes of the aggregates formed during rhodanese folding increase from 225 to 325 nm over 45 min and they become increasingly heterogeneous. Glycerol addition or the application of high hydrostatic pressure improved the final refolding yields by stabilizing smaller particles. Although addition of glycerol into the refolding mixture blocks the formation of unproductive aggregates, it cannot dissociate them back to productive intermediates. The presence of 3.9 M urea keeps the aggregates small, and they can be dissociated to monomers by high hydrostatic pressure even after 1 h of incubation. These studies suggest that early associated intermediates formed during folding can be reversed to give active species.

Animals↗

PubMed2005

Post-translational regulation of mercaptopyruvate sulfurtransferase via a low redox potential cysteine-sulfenate in the maintenance of redox homeostasis.

3-Mercaptopyruvate sulfurtransferase (MST) (EC 2.8.1.2), a multifunctional enzyme, catalyzes a transsulfuration from mercaptopyruvate to pyruvate in the degradation process of cysteine. A stoichiometric concentration of hydrogen peroxide and of tetrathionate (S(4)O(6)(2-)) inhibited rat MST (k(i) = 3.3 min(-1), K(i) = 120.5 microM and k(i) = 2.5 min(-1), K(i) = 178.6 microM, respectively). The activity was completely restored by dithiothreitol or thioredoxin with a reducing system containing thioredoxin reductase and NADPH, but glutathione did not restore the activity. On the other hand, an excess molar ratio dose of hydrogen peroxide inactivated MST. Oxidation with a stoichiometric concentration of hydrogen peroxide protected the enzyme against reaction by iodoacetate, which modifies a catalytic Cys(247), suggesting that Cys(247) is a target of the oxidants. A matrix-assisted laser desorption/ionization-time-of-flight mass spectrometric analysis revealed that hydrogen peroxide- and tetrathionate-inhibited MSTs were increased in molecular mass consistent with the addition of atomic oxygen and with a thiosulfate (S(2)O(3)(-)), respectively. Treatment with dithiothreitol restored modified MST to the original mass. These findings suggested that there was no nearby cysteine with which to form a disulfide, and mild oxidation of MST resulted in formation of a sulfenate (SO(-)) at Cys(247), which exhibited exceptional stability and a lower redox potential than that of glutathione. Oxidative stress decreases MST activity so as to increase the amount of cysteine, a precursor of thioredoxin or glutathione, and furthermore, these cellular reductants restore the activity. Thus the redox state regulates MST activity at the enzymatic level, and on the other hand, MST controls redox to maintain cellular redox homeostasis.

Animals↗

PubMed2003

Tepidimonas aquatica sp. nov., a new slightly thermophilic beta-proteobacterium isolated from a hot water tank.

A bacterial isolate, with an optimum growth temperature of about 50 degrees C, was recovered from a domestic hot water tank in Coimbra. Phylogenetic analysis using 16S rRNA gene sequence indicated that strain CLN-1T is a member of the beta-Proteobacteria and represents a new species of the genus Tepidimonas. The major fatty acids of strain CLN-1T are 16:0, 17:0 cyclo and 16:1 omega7c. Ubiquinone 8 is the major respiratory quinone, the major polar lipids are phosphatidylethanolamine, and phosphatidylglycerol. The new isolate is aerobic and facultatively chemolithoheterotrophic. Thiosulfate and tetrathionate are oxidized to sulfate in the presence of a metabolizable carbon source. Strain CLN-1T grows on amino acids and organic acids, but this organism does not assimilate carbohydrates. Glycerol is the only polyol assimilated. Resinic acids, namely abietic acid, dehydroabietic acid and isopimaric acid are not degraded. On the basis of the phylogenetic analyses, physiological and biochemical characteristics, we propose that strain CLN-1T represents a new species for which we offer the name Tepidimonas aquatica.

Aerobiosis↗

PubMed1985

Acetone potentiation of acute acetonitrile toxicity in rats.

The purpose of these studies was to investigate the nature and mechanism of a toxicologic interaction between acetonitrile and acetone. Results of oral dose-response studies utilizing a 1:1 (w/w) mixture of acetonitrile and acetone, or varying doses of acetonitrile administered together with a constant dose of acetone, indicated that acetone potentiated acute acetonitrile toxicity three- to fourfold in rats. The onset of severe toxicity (manifested by tremors and convulsions) was delayed in the groups dosed with both solvents compared to the groups that received acetonitrile or acetone alone. Blood cyanide (a metabolite of acetonitrile) and serum acetonitrile and acetone concentrations were measured after oral administration of 25% aqueous solutions of acetonitrile, acetone, or acetonitrile plus acetone. Concentrations of cyanide in the blood of rats given acetonitrile plus acetone remained near baseline, in contrast to the high concentrations found in rats dosed with acetonitrile alone. At 34-36 h, high blood cyanide concentrations were found in rats dosed with both of the solvents. This delayed onset of elevation of blood cyanide coincided with the occurrence of clinical signs and with the disappearance of serum acetone. In further pharmacokinetic studies, blood cyanide concentrations were measured after similar dosage regimens of acetone and acetonitrile. Peak cyanide concentrations were found to be significantly greater in rats dosed with both solvents than in rats given only acetonitrile. Administration of either sodium thiosulfate or a second dose of acetone prevented the toxicity associated with exposure to both solvents. These results suggest that the effects of acetone on acetonitrile toxicity are due to a biphasic effect on the metabolism of acetonitrile to cyanide, that is, an initial inhibition followed by a stimulation of this metabolism upon acetone elimination.

Acetone↗

PubMed1972

The permeability of thin lipid membranes to bromide and bromine.

Thin lipid (optically black) membranes were made from sheep red cell lipids dissolved in n-decane. The flux of Br across these membranes was measured by the use of tracer (82)Br. The unidirectional flux of Br (in 50-100 mM NaBr) was 1-3 x 10(-12) mole/cm(2)sec. This flux is more than 1000 times the flux predicted from the membrane electrical resistance (>10(8) ohm-cm(2)) and the transference number for Br(-) (0.2-0.3), which was estimated from measurements of the zero current potential difference. The Br flux was not affected by changes in the potential difference imposed across the membrane (+/-60 mv) or by the ionic strength of the bathing solutions. However, the addition of a reducing agent, sodium thiosulfate (10(-3)M), to the NaBr solution bathing the membrane caused a 90% reduction in the Br flux. The inhibiting effect of S(2)O(3) (=) suggests that the Br flux is due chiefly to traces of Br(2) in NaBr solutions. As expected, the addition of Br(2) to the NaBr solutions greatly stimulated the Br flux. However, at constant Br(2) concentration, the Br flux was also stimulated by increasing the Br(-) concentration, in spite of the fact that the membrane was virtually impermeable to Br(-). Finally, the Br flux appeared to saturate at high Br(2) concentrations, and the saturation value was roughly proportional to the Br(-) concentration. These results can be explained by a model which assumes that Br crosses the membrane only as Br(2) but that rapid equilibration of Br between Br(2) and Br(-) occurs in the unstirred layers of aqueous solution bathing the two sides of the membrane. A consequence of the model is that Br(-) "facilitates" the diffusion of Br across the unstirred layers.

Animals↗

PubMed1992

Simultaneous determination of arsenic and antimony species in environmental samples using bis(trifluoroethyl)dithiocarbamate chelation and supercritical fluid chromatography.

Simultaneous separation and quantitation of arsenic(III) and antimony(III) can be achieved by extraction with lithium bis(trifluoroethyl)dithiocarbamate followed by supercritical fluid chromatographic (SFC) analysis. Arsenic(V) and antimony(V) are extracted after reduction with potassium iodide and sodium thiosulfate. Detection limits of 7 pg As and 11 pg Sb are achieved using this extraction method and SFC. Application to natural water and biological sample analysis is discussed.

Antimony↗

PubMed1985

Active absorption of selenate by rat ileum.

Intestinal absorption of selenate and selenite in rats was investigated in vitro by using everted sacs of the duodenum, jejunum and ileum. Only the ileal sacs incubated with selenate accumulated selenium in the serosal fluid during the incubation. Selenium transport across the ileum did not occur against a concentration gradient when selenite instead of selenate was present in the incubation medium. Sulfate and thiosulfate significantly inhibited ileal selenate transport. Decreasing the activity of the Na+,K+-ATPase, by the addition of ouabain, resulted in a significant reduction of concentrative selenate transport by the ileum. Furthermore L-leucine, but not D-glucose and D-galactose, significantly reduced selenium absorption by ileal sacs incubated with selenate. It is concluded from these results that selenate is transported actively by the ileal mucosa and that a common transport mechanism for selenate and sulfate exists. The Na+-gradient across the intestinal brush border membrane seems to be capable of energizing active ileal selenate transport.

Animals↗

PubMed1993

Dose intensification of cisplatin chemotherapy through biweekly administration.

PURPOSE: Dose intensity (DI, expressed in mg/m2/wk) may be an important factor in the clinical use of cisplatin (DDP). We have explored the shortening of the cycle interval as a way to increase the DI of DDP. PATIENTS AND METHODS: DDP 180 mg/m2 was given intravenously (i.v.) over 4 hours; sodium thiosulfate (STS) was given i.v. in the opposite arm at a loading dose of 4 g/m2, followed by 12 g/m2 over 6 hours. Each cycle was repeated every two weeks. Seventy-five cycles were administered to 28 patients in this clinical trial. RESULTS: In 19 patients who received 2 or more cycles of chemotherapy, a delay of three or more days was required on 17/66 courses (26%); the mean DDP DI actually received by these patients was 83 mg/m2/wk (88% of the planned DI). The major side effect was ototoxicity; this occurred in 9 patients (33%), but none required a hearing aid. Myelosuppression was moderate with thrombocytopenia greater than neutropenia. Nephrotoxicity (creatinine > 2 mg/dl) occurred on only 2 cycles (3%). Three patients (11%) developed symptoms of peripheral neuropathy. In 23 evaluable patients, the overall response rate was 39%. CONCLUSION: It is feasible to give 180 mg/m2 of DDP and STS every two weeks with tolerable nephrotoxicity but without blocking other types of toxicity, such as myelosuppression and ototoxicity. The shortening of cycle intervals resulted in a markedly increased DI.

Adult↗

PubMed2001

Inhibitors of ethylene synthesis inhibit auxin-induced stomatal opening in epidermis detached from leaves of Vicia faba L.

Using leaf epidermis from Vicia faba, we tested whether auxin-induced stomatal opening was initiated by auxin-induced ethylene synthesis. Epidermis was dark-incubated in buffered KNO3 containing 0.1 mM alpha-napthalene acetic acid or 1 mM indole-3-acetic acid. Maximum net opening was ca. 4 micron after 6 h. Opening was reversed by 20 microM ABA, 0.1 mM CaCl2. 1-Aminocyclopropane carboxylic acid (ACC) synthase catalyzes synthesis of ACC, the immediate precursor to ethylene. Auxin-induced stomatal opening was fully inhibited by 10 microM 1-aminoethoxyvinylglycine (AVG), an ACC synthase inhibitor. In solutions containing AVG, auxin-induced opening was restored in a concentration-dependent manner by exogenous ACC, but not in control solutions lacking an auxin. ACC-mediated reversal of AVG-inhibition of stomatal opening was inhibited by alpha-aminoisobutyric acid (AIB), an inhibitor of ACC oxidase, the last enzyme in the ethylene biosynthetic pathway, by 10 microM silver thiosulfate (STS), an inhibitor of ethylene action, and by 20 microM ABA, 0.1 mM CaCl2. CoCl2, an inhibitor of ethylene synthesis, also inhibited auxin-induced opening. Both STS and CoCl2 inhibited opening induced by light or by fusicoccin, but neither light- nor fusicoccin-induced opening was inhibited by AVG. These results support the hypothesis that auxin-induced stomatal opening is mediated through auxin-induced ethylene production by guard cells.

Amino Acid Oxidoreductases↗

PubMed1997

Toxicity identification of poultry litter aqueous leachate.

Poultry litter is a mixture of excreta, feed, feathers, and bedding material. Poultry litter is useful as a fertilizer due to the presence of nitrogen, phosphorus, and potassium. Litter is commonly used for growing corn, soybeans, potatoes, tomatoes, leafy vegetables, and cover crops. The aqueous leachate of poultry litter has been shown to exhibit toxicity to a variety of indicator organisms. The objective of this research was to identify classes of toxicants in the litter aqueous leachate. The aqueous extract of poultry litter was subjected to toxicity identification tests approved by the United States Environmental Protection Agency that use Ceriodaphnia dubia as the test organism. Tests performed included pH adjustment, filtration, aeration, C18 solid-phase extraction, EDTA addition, sodium thiosulfate addition, and extraction through zeolite. Zeolite extraction, filtration at low pH, and aeration at low pH reduced overall toxicity by 68, 20, and 22%, respectively. The major sources of toxicity appear to be ammonia and anionic organic compounds. Toxicity was apparently not due to the presence of heavy metals or oxidants.

Ammonia↗

PubMed2000

The effects of sulfur, thiol, and thiol inhibitor compounds on arsine-induced toxicity in the human erythrocyte membrane.

The mechanism of arsine (AsH(3)) toxicity is not completely understood. The first cytotoxic effect of AsH(3) is disruption of ion homeostasis, with a subsequent hemolytic action. The only accepted treatment for AsH(3) toxicity is exchange transfusion of the blood. In this study the effect of sulfur, sulfur compounds, thiol-containing compounds, and thiol inhibitors on AsH(3)-induced disruption of membrane transport and hemolysis in human erythrocytes was investigated in vitro. Elemental sulfur, sodium thiosulfate, 5, 5'-dithio-bis(2-nitrobenzoic acid), and meso-2,3-dimercaptosuccinic acid were successful in delaying hemolysis, but the most successful agent was the sulfhydryl inhibitor, N-ethylmaleimide (NEM). This indicated that sulfhydryl groups, possibly membrane sulfhydryls, are major factors in the hemolytic mechanism of AsH(3). Measuring intracellular ion concentrations tested the effect of NEM on AsH(3)-induced disruption of membrane transport. AsH(3) alone caused all ions tested to flow with their concentration gradients: Intracellular K+ and Mg++ decreased, whereas Na+, Cl-, and Ca++ increased. NEM was unable to prevent ion loss except for Ca++, whose increase was prevented for 1 h after AsH(3) treatment. The influx of Ca++ in AsH(3)-treated erythrocytes is an irreversible event leading to hemolysis. Reduction of oxygenated hemoglobin to carboxyhemoglobin completely inhibited AsH(3)-induced hemolysis. In addition, AsH(3) and NEM had no direct chemical interactions. We concluded that membrane sulfhydryl groups are likely targets of AsH(3) toxicity, with NEM being able to prevent AsH(3)-induced hemolysis.

Adult↗