SEARCH · PubMed Health

Results for “THIOCYANATES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 109 records · Page 6Linked to original sources

PubMed1990

[Determination of thiocyanate in serum with ion-selective liquid membrane electrodes].

The manufacture of a liquid membrane type thiocyanate ion selective electrode on the basis of crystalviolet thiocyanate or methylene blue thiocyanate solved in nitrobenzene is described. This electrodes are available for the determination of the thiocyanate ion in agents with high levels on chlorid or protein, for instance in serum. Thiocyanate levels in serum from smokers and nonsmokers determinated by this electrodes differ significant from values that were obtained by the barbituric acid method, but they were in good agreement with values determinated by ion exchange chromatography. It can be assumed that its possible to ascertain the part of the dissociated thiocyanate by means of the ion selective electrodes and the ion exchange chromatography.

Chemical Phenomena↗

PubMed1979

Method for determining thiocyanate in serum and urine.

We describe a method for rapid and specific measurement of thiocyanate in serum or urine. We separate thiocyanate from interfering compounds by adsorbing it on an anion-exchange resin that has special affinity for thiocyanate, then eluting with sodium perchlorate. The eluted thiocyanate is quantified by a modified König reaction, sodium hypochlorite being used as the chlorinating reagent. Analytical recovery of thiocyanate added to serum and urine was quantitative; the coefficient of variation was 2.3% for both within-day and between-day precision. Cyanide and certain antibiotics interfere, but may be eliminated by including additional washing steps in the usual procedure. The proposed procedure was compared with another method, based on the oxidation of thiocyanate to cyanide. Agreement was satisfactory, both for serum and urine.

Chromatography, Ion Exchange↗

PubMed1982

[Comparative studies on the determination of thiocyanate in biological materials (author's transl)].

On verifying methods for the determination of thiocyanate in biological materials, we started from the technique as described by Boxer and Rickards [5]. In different methods, the accuracy of the data obtained is affected by the deproteinization process or interfered with iron (III) ions or pyridine/benzidine, the deproteinization process being the decisive factor. This holds true especially in respect of interfering factors that remain in the supernatant (low-molecular amino compounds) and in respect of the coprecipitation of thiocyanate, the nature of the respective biological material playing an important part in both cases. At higher thiocyanate concentrations, pretreatment with a denaturing agent that is commonly used to deproteinization of human and bovine sera involves a small loss of thiocyanate due to coprecipitation. In case of high demands on reproducibility and accuracy of the analytical results, and in case of special analytical problems, isolation of thiocyanate is absolutely necessary (chromatography on Sephadex, aeration after conversion to hydrogen cyanide). Gas chromatography is suited for determining thiocyanate in whole blood.

Amino Acids↗

PubMed1998

Cloning of genes coding for the three subunits of thiocyanate hydrolase of Thiobacillus thioparus THI 115 and their evolutionary relationships to nitrile hydratase.

Thiocyanate hydrolase is a newly found enzyme from Thiobacillus thioparus THI 115 that converts thiocyanate to carbonyl sulfide and ammonia (Y. Katayama, Y. Narahara, Y. Inoue, F. Amano, T. Kanagawa, and H. Kuraishi, J. Biol. Chem. 267:9170-9175, 1992). We have cloned and sequenced the scn genes that encode the three subunits of the enzyme. The scnB, scnA, and scnC genes, arrayed in this order, contained open reading frames encoding sequences of 157, 126, and 243 amino acid residues, respectively, for the beta, alpha, and gamma subunits, respectively. Each open reading frame was preceded by a typical Shine-Dalgarno sequence. The deduced amino-terminal peptide sequences for the three subunits were in fair agreement with the chemically determined sequences. The protein molecular mass calculated for each subunit was compatible with that determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. From a computer analysis, thiocyanate hydrolase showed significant homologies to bacterial nitrile hydratases known to convert nitrile to the corresponding amide, which is further hydrolyzed by amidase to form acid and ammonia. The two enzymes were homologous over regions corresponding to almost the entire coding regions of the genes: the beta and alpha subunits of thiocyanate hydrolase were homologous to the amino- and carboxyl-terminal halves of the beta subunit of nitrile hydratase, and the gamma subunit of thiocyanate hydrolase was homologous to the alpha subunit of nitrile hydratase. Comparisons of the catalytic properties of the two homologous enzymes support the model for the reaction steps of thiocyanate hydrolase that was previously presented on the basis of biochemical analyses.

Amino Acid Sequence↗

PubMed1999

Kinetics and modeling of autotrophic thiocyanate biodegradation.

The biokinetic parameters for autotrophic systems are difficult to obtain and are often mistakenly determined because the size of the autotrophic population in mixed (i.e., heterotrophic and autotrophic) cultures cannot be accurately estimated. This article presents a systematic approach, combining bioenergetic calculations and experimental data, to obtain values of the biokinetic parameters pertinent to the aerobic, autotrophic biodegradation of thiocyanate. Nonlinear regression techniques were employed using both initial thiocyanate utilization rate data and single thiocyanate depletion curves. Both types of data were necessary to overcome the problems arising from the linear nature of the substrate depletion curves and the high correlation of the biokinetic model parameters inherent in nonlinear regression analysis. The aerobic biodegradation of thiocyanate followed a substrate inhibition pattern that was successfully described by the Haldane-Andrews model. Although regression analysis did not yield unique biokinetic parameter estimates, the following parameter value ranges were obtained: maximum specific substrate utilization rate (k), 0.26 to 0.44 mg SCN-/mg biomass h; half-saturation coefficient (Ks), 2.3 to 7.1 mg SCN-/L; and inhibition coefficient (Ki), 28 to 109 mg SCN-/L. Based on the estimated biokinetic parameter values, a design and operation diagram was constructed that depicts the steady-state thiocyanate concentration as a function of solids retention time for a completely mixed, continuous-flow reactor.

Bacteria↗

PubMed1990

The effect of sodium tetrathionate on cyanide conversion to thiocyanate by enzymatic and non-enzymatic mechanisms.

Sodium tetrathionate has been proposed as a cyanide antidote despite its reported toxicology and inhibitory effect on rhodanese. We investigated the effect of tetrathionate and an analog, dithionite, on rhodanese activity because of their structural similarity to thiosulfate, a known sulfane sulfur donor for this enzyme. Rhodanese activity of guinea pig liver homogenate was assayed by measuring the formation of ferric thiocyanate complex at 460 nm. With thiosulfate as a substrate, the Km for rhodanese was 6.7 mM and the Vmax was 0.67 mumol thiocyanate min-1 mg-1 protein. The conversion of cyanide to thiocyanate by rhodanese was inhibited in the presence of tetrathionate at the millimolar concentration (e.g. 1 mM) range. Dithionite had a negligible effect on rhodanese activity. Neither thiosulfate (1-100 mM) nor dithionite produced significant amounts of thiocyanate from cyanide spontaneously (i.e. non-enzymatically). However, in the absence of rhodanese, tetrathionate (1.0, 10.0 and 100.0 mM) produced a dose-dependent increase in thiocyanate. These data suggest that tetrathionate detoxifies cyanide non-enzymatically, which may, in part, account for its antidotal effects.

Animals↗

PubMed1995

Oxidative conversion of thiocyanate to cyanide by oxyhemoglobin during acid denaturation.

Human oxyhemoglobin (Hb-O2) converts thiocyanate to cyanide under acidic conditions, in a hemoglobin and thiocyanate concentration-dependent manner. Other naturally occurring hemoglobin derivatives and hematin did not result in cyanide-producing activity. Pre-denaturation completely destroyed cyanide production. In the presence of 10% phosphoric acid, 12 microM cyanide was produced by 1 mM Hb-O2 (per heme) and 1 mM thiocyanate. This conversion was observed over a wide range of acidic pH levels at 50 degrees C, with an optimal pH of 4. The production of cyanide under strong acidic conditions was completed within 1 s, while under weak acidic conditions (pH approximately 5) the production gradually increased for half an hour. Under both conditions, the time course for cyanide production coincided with the disappearance of this converting activity. Thiocyanate conversion by acidified Hb-O2 was completely suppressed by the addition of ascorbic acid, significantly suppressed by superoxide anion radical (O2-) scavengers or thiourea, but not effected by scavengers of hydroxyl radical, singlet oxygen, and protein radical. In addition to acidification, other processes for denaturation of Hb-O2 resulted in detectable production of cyanide, e.g., heating, extraction by organic solvents, and incubation with denaturating or oxidative reagents. These data suggest that O2- generated during Hb-O2 denaturation and also a hydroperoxyl radical converted under acidic conditions are the oxidizing species that convert thiocyanate to cyanide.

Biotransformation↗

PubMed1988

Serum thiocyanate levels as an objective measure of smoking habits in epidemiological studies.

The relationship between smoking habits and plasma thiocyanate levels has been evaluated in four adult samples of the general population containing men and women aged 20-84 and in a sample of 11-year-old non-smoking children of both sexes, for a total of 7577 individuals. Mean levels of plasma thiocyanate was found be approximately 20 mumol/l in children, 30 mumol/l in non-smoking adults and increasingly higher in smoking adults. The slopes of the regression equations of thiocyanate on cigarettes smoked per day range from 3.041 to 5.740, with correlation coefficients of from 0.638 to 0.809. In another occupational sample of 2802 men aged 46 to 65, where the correlation coefficient (between cigarette consumption and thiocyanate) was only 0.49, plasma thiocyanate was a better predictor of 4 year fatal events than cigarette consumption, 4 other covariates being considered in the same multivariate model.

Adult↗

PubMed1975

Effect of cyanide antidotes on the metabolic conversion of cyanide to thiocyanate.

The excretion of thiocyanate following the administration of equitoxic doses of cyanide to unprotected mice and to animals pretreated with various cyanide antidotes has been studied. The results demonstrate that cyanide given alone or to animals pretreated with thiosulfate is extensively converted to thiocyanate. Animals pretreated with sodium nitrite or a combination of nitrite and sodium thiosulfate excreted even higher amounts of thiocyanate. This demonstrates that cyanide originally detoxified by combination with methemoglobin is ultimately converted to thiocyanate in the animal body. Pretreatment of animals with cobalt compounds (cobaltous chloride or dicobalt-EDTA) or a combination of cobalt compounds and thiosulfate resulted, on the other hand, in a less efficient conversion of cyanide to thiocyanate. The cyanide detoxified by trapping as highly undissociated cobalt-cyanide complexes is instead excreted in the urine, as demonstrated by detection of high amounts of cobalt ions and strongly complex-bound cyanide in the urine from animals treated with cobalt compounds and cyanide. A method for the determination of cyanide present as cobalt-cyanide complexes is described and its forensic application is proposed.

Animals↗

PubMed1987

Chloride-thiocyanate interactions in frog muscle anion-conducting channels at pH 5.

Bi-ionic membrane potential measurements and three-microelectrode voltage clamp experiments have been performed on surface fibres of Xenopus laevis sartorius muscle at various mole fractions of SCN- in Cl- in the perfusate, at pH 5. Potassium was replaced in the test solutions by rubidium and/or tetraethylammonium and when the mole fraction of anions was changed the measured membrane potential changed to a new constant (i.e. time-independent) value. Over a mole fraction range of 0.05-0.95 the permeability ratio of thiocyanate to chloride was independent of [SCN-]. When the bathing solution was completely changed from control to one containing thiocyanate the change in membrane potential indicated that the permeability ratio, PSCN/PCl is close to 5.9. Inward voltage clamp currents (chloride efflux) were suppressed in the presence of thiocyanate, the degree of suppression increasing with [SCN-]. Outward currents (anion influx) were not substantially altered, suggesting that it is only the voltage-dependent anion current that is sensitive to SCN-. The results are interpreted as indicating that there is a binding site in the anion-conducting channel, accessible to the extracellular space, that must be occupied by an anion in order for the channel to be "open". But that for ion traverse to be complete, the ion at the binding site must be exchanged. If the site is occupied by thiocyanate, the more strongly bound ion, the thiocyanate blocks the channel. The bi-ionic permeability ratio is thought to reflect the ratio of the binding constants for the anions at that site.

Animals↗

PubMed1982

Thiocyanate transport across fish intestine (Pleuronectes platessa).

When bathed on both sides with identical chloride-containing salines the in vitro preparation of the plaice intestine maintains a negative (serosa to mucosa) short-circuit current of 107 +/- 11 muA/cm2, a transepithelial potential difference of 5.5 +/- 0.6 mV (serosa negative), and a mean mucosal membrane potential of -45.4 +/- 0.6 mV. Under these conditions the intracellular chloride activity is 32 mM. If chloride in the bathing media is partially, or completely substituted by thiocyanate the measured electrical parameters do not change but transepithelial flux determinations show a reduction in chloride fluxes and the presence of a significant thiocyanate flux. The addition of piretanide (10-4M) reduced the short-circuit current and the mucosa-to-serosa fluxes of chloride and thiocyanate; this inhibition is similar to the effect of piretanide on chloride transport in this tissue. The results indicate that thiocyanate is transported in this tissue via the piretanide-sensitive "chloride" pathway and are compared with the effects of thiocyanate on other tissues reported in the literature.

Animals↗

PubMed1991

Monitoring cyanide and thiocyanate concentrations during infusion of sodium nitroprusside in children.

Over a 19-month period, all requests for blood cyanide and/or serum thiocyanate concentrations to the Clinical Laboratory of The Children's Hospital, Boston, were reviewed in order to determine how physicians screen for nitroprusside-related toxicity. During that period, 52 patients receiving nitroprusside were monitored for cyanide and/or thiocyanate toxicity. Overall, there were 62 cyanide and 86 thiocyanate determinations. None of the thiocyanate determinations and five of the cyanide concentrations were within the toxic range as established by the reference laboratory, and no patient displayed signs or symptoms of toxicity which could not also be explained by their underlying illness. Our findings suggest that while physicians are concerned with nitroprusside toxicity in children, there exists no apparent consensus as to how to monitor for this toxicity. The results also indicate that the relationship between blood cyanide or serum thiocyanate concentrations and clinical evidence of toxicity is not straightforward and requires further delineation.

Adolescent↗

PubMed1982

Effect of inorganic phosphate and benzyl thiocyanate on the activity of anhydrotetracyline oxygenase in Streptomyces aureofaciens.

The level of anhydrotetracyline oxygenase (an enzyme catalyzing the penultimate reaction in the biosynthesis of tetracyline) in Streptomyces aureofaciens was substantially influenced by the amount of inorganic phosphate and by the presence of benzyl thiocyanate in the cultivation medium. Phosphate decreased the specific activity of the enzyme, particularly when added to a growing culture. On the other hand, benzyl thiocyanate increased the specific activity of the enzyme. Its effect was most conspicuous in the growth phase. The effect of benzyl thiocyanate was more pronounced in the low-production strain than in the producing variant. Inorganic phosphate and benzyl thiocyanate did not influence the enzyme activity in vitro. Phosphate added to the growing cultures was readily absorbed by the cells. During this time the enzyme synthesis was repressed, derepresion occurred only after exhaustion of phosphate from the medium. The stimulatory effect of benzyl thiocyanate on the enzyme synthesis was not reversed by the inorganic phosphate added.

Oxygenases↗

PubMed1984

Thiocyanates and iodine in endemic goiter in Italy.

Urinary iodine (I) and serum and urinary thiocyanates (SCN-) were determined in sample groups from 12 areas of endemic goiter in Italy. The mean urinary I level of 637 subjects with thyroid 0 was 67 +/- 31 (mean +/- SD) microgram/liter, that of 648 with goiter 54 +/- 29 micrograms/liter. Mean serum and urinary SCN- were 2.44 +/- 1.36 mg/liter and 2.58 +/- 1.36 mg/liter in 887 and 1531 subjects, respectively. The thiocyanates data enabled a distinction to be drawn between two groups (populations). Population I included 73% of the adults and 92% of the school-children (6-16 yr). Its thiocyanate values were logarithmically spread around means of 1.24 +/- 0.6 mg/liter (serum) and 1.24 +/- 0.57 mg/liter (urine), whereas those of population II were widely dispersed around means of 6.1 +/- 3.0 mg/liter and 8.08 +/- 5.5 mg/liter respectively. The boundary between the two populations was set at 3 mg/liter urine SCN-. This distinction was substantiated by the fact that 90% of those in population II smoked 10 or more cigarettes a day, whereas population I comprised occasionally smokers only. It is believed that only the values in population I can be regarded as representative of thiocyanates either endogenous or due to dietary dietary intake: these values never differed more than 60% regardless of the areas, seasons, or dietary habits. As urinary SCN- levels rose, there was also an increase in urinary iodine excretion within certain limits. This, however, did not interfere with thyroid secretion. The urinary I/SCN- ratio was lower in subjects with goiter. This was because their iodine levels were lower, whereas SCN- values were much the same in subjects with and without goiter. We have found no correlation between thiocyanate itself and goiter.

Adolescent↗

PubMed2004

Do folic acid and thiocyanate have a preventive effect on exogenously induced disturbances of embryonic cranial development?

The preventive influence of folic acid and thiocyanate on procarbazine-induced disturbances of embryonic cranial development was investigated on experimental animals. Low dosages of folic acid or thiocyanate demonstrated no prophylactic effect. When thiocyanate was administered alone, an increased cleft rate was unexpectedly found for the secondary palate. The combined application of folic acid and thiocyanate showed a cleft-prophylactic effect in the secondary palate in addition to growth protection in the primary palate. It can be assumed that thiocyanate has a positive effect on chondral and osseous growth of the palate during the post-sensitive phase of embryogenesis, while in the sensitive phase, it can function as a carrier for teratogenous and toxic substances.

Animals↗

PubMed2006

Determination of trace amounts of thiocyanate by a new kinetic procedure based on an induction period.

A new, simple and sensitive kinetic spectrophotometric method with no need for removing of interfering substances is proposed for the determination of thiocyanate ion in biological and water samples. The procedure is based on the inhibiting effect of thiocyanate on the sodium periodate-potassium bromide-meta cresol purple (MCP) system in acidic media. The induction period of the reaction is proportional to the SCN- concentration. The decolorization of meta cresol purple by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. Under optimum conditions, thiocyanate can be determined in the range of 0.02-0.8 microg ml(-1) with a 3sigma detection limit of 5 ng ml(-1). The relative standard deviations for 10 replicate determinations of 0.060, 0.10 and 0.50 microg ml(-1) thiocyanate are 3.7, 2.4 and 1.0%, respectively. This method has been successfully used to the determination of thiocyanate content in smokers and non-smokers saliva and spiked water sample.

Bromides↗

PubMed2003

An NMR and circular dichroism study of the interaction of thiocyanate with human and cross-linked hemoglobin: identification of Lys-alpha-99 as a possible dissociation linked binding site.

The interaction of thiocyanate with human native and cross-linked oxyhemoglobin (oxyHb), and methemoglobin (metHb) has been investigated by optical spectroscopy, circular dichroism (CD) and nuclear spin lattice relaxation rate measurements. The interaction of thiocyanate anion with human hemoglobin has been investigated by NMR measurements of the nuclear spin lattice relaxation rate of N(15) labeled thiocyanate in the presence of cyanomethemoglobin and cross-linked cyanomethemoglobin. Results show that thiocyanate is located approximately 8.9 and 6.2 A away from the heme group in cyanomethemoglobin and cross-linked cyanomethemoblobin, respectively. These results are consistent with the binding of SCN(-) at the lys-alpha-99 in the unmodified hemoglobin. Since this site is blocked in the cross-linked hemoglobin, the binding site is different. Results show that one mole of SCN(-) is binding to one mole of oxyhemoglobin suggesting that binding at the lys-alpha-99 is linked to dissociation of the hemoglobin tetramer into dimers due to its location at the alpha(1)beta(2) interface. Circular dichroism studies show that the interaction of thiocyanate with oxyHb decreases the optical rotation at 240 nm indicating a conformational change of the protein, which influences the electronic transitions of a number of peptide bonds or (and) a few aromatic side chains.

Binding Sites↗

PubMed2002

Variations of lactoperoxidase activity and thiocyanate content in cows' and goats' milk throughout lactation.

Lactoperoxidase activity and thiocyanate content were monitored in the milks of seven individual cows and six goats during lactation. Lactoperoxidase activity exhibited a cyclic pattern with alternating peaks and troughs throughout lactation. Extremely large variations were observed between and within animals. For example, lactoperoxidase activity ranged from 0.05-5.60 U/ml for one cow on different sampling days. Variations between cows were also large, ranging from 0.98-5.1 U/ml on a specific sampling day. Mean lactoperoxidase activity in cows ranged from 1.5-2.7 U/ml with an overall mean of 2.3 +/- 1.0 U/ml while the thiocyanate concentration ranged from 6.0-10.2 micrograms/ml with an overall average of 8.5 +/- 5.1 micrograms/ml. Lactoperoxidase activity means for goats ranged from 0.04-0.16 U/ml with a grand mean of 0.1 +/- 0.06 U/ml while the thiocyanate content means ranged from 6.6-8.2 micrograms/ml with a grand mean of 7.0 +/- 2.59 micrograms/ml. There was no correlation between lactoperoxidase activity and thiocyanate content in either cows' (R2 = 0.011) or goats' (R2 = 0.015) milk. These experiments have revealed that lactoperoxidase activity is affected by many factors including the individual animals, species, feed and stage of lactation. Therefore the exogenous supply of thiocyanate and hydrogen peroxide needed to activate the lactoperoxidase system for raw milk preservation will vary in quantity depending on these factors.

Animals↗