Showing papers on "Cyanide published in 1991"
TL;DR: In this paper, the authors measured cyanide concentrations in blood samples obtained at the scene of residential fires from 109 fire victims before they received any treatment, and compared the results with those in 114 persons with drug intoxication (40 subjects), carbon monoxide intoxication (29 subjects), or trauma (45 subjects).
Abstract: Background The nature of the toxic gases that cause death from smoke inhalation is not known. In addition to carbon monoxide, hydrogen cyanide may be responsible, but its role is uncertain, because blood cyanide concentrations are often measured only long after exposure. Methods We measured cyanide concentrations in blood samples obtained at the scene of residential fires from 109 fire victims before they received any treatment. We compared the results with those in 114 persons with drug intoxication (40 subjects), carbon monoxide intoxication (29 subjects), or trauma (45 subjects). The metabolic effect of smoke inhalation was assessed by measuring plasma lactate at the time of admission to the hospital in 39 patients who did not have severe burns. Results. The mean (±SD) blood cyanide concentrations in the 66 surviving fire victims (21.6±36.4 μmol per liter, P<0.001) and the 43 victims who died (116.4±89.6 μmol per liter, P<0.001) were significantly higher than those in the 114 control subjects (5.0±5.5 ...
395 citations
173 citations
TL;DR: An acid hydrolysis method was developed for cyanide analysis in cassava and gave reasonable agreement with results obtained by the use of linamarase, and adequate recoveries of added linamarin (70–95% dependent on conditions).
Abstract: Guided by the results of NMR experiments on the reactivity of linamarin in alkali and acid, an acid hydrolysis method was developed for cyanide analysis in cassava. Hydrolysis in 2·0 M H2SO4 at 100°C for 50 min of a cassava extract produced cyanohydrins which rapidly decomposed to cyanide ion in alkali. Excess pH 6 buffer was added, followed by chloramine-T and pyridine/barbituric acid (Konig reaction) to produce a purple solution which was measured spectrophotometrically at 583 nm. The colour intensity depended on pH and phosphate concentration, hence accurate results required similar solution conditions for KCN standards. The method gave reasonable agreement with results obtained by the use of linamarase, and adequate recoveries of added linamarin (70–95% dependent on conditions). Acid hydrolysis is cheaper than the enzymic method using linamarase, which is expensive. Also the pyridine/barbituric acid reagent used in the acid hydrolysis method is cheaper and more stable than the pyridine/pyrazolone normally used in the enzymic method. Six locally grown cultivars gave <30 mg HCN kg−1 fresh tuber, and one cultivar (SM 1–150) contained only 4 mg HCN kg−1 fresh weight. Analyses of the same cultivar grown more recently gave values of 13–27 mg HCN kg−1, showing the need for a study of the environmental factors influencing the cyanide content of cassava tubers.
164 citations
TL;DR: Enzyme purification established that cyanide hydrolysis by A. xylosoxidans subsp.
Abstract: A cyanide-metabolizing bacterium, strain DF3, isolated from soil was identified as Alcaligenes xylosoxidans subsp. denitrificans. Whole cells and cell extracts of strain DF3 catalyzed hydrolysis of cyanide to formate and ammonia (HCN + 2H2O----HCOOH + NH3) without forming formamide as a free intermediate. The cyanide-hydrolyzing activity was inducibly produced in cells during growth in cyanide-containing media. Cyanate (OCN-) and a wide range of aliphatic and aromatic nitriles were not hydrolyzed by intact cells of A. xylosoxidans subsp. denitrificans DF3. Strain DF3 hydrolyzed cyanide with great efficacy. Thus, by using resting induced cells at a concentration of 11.3 mg (dry weight) per ml, the cyanide concentration could be reduced from 0.97 M (approximately 25,220 ppm) to less than 77 nM (approximately 0.002 ppm) in 55 h. Enzyme purification established that cyanide hydrolysis by A. xylosoxidans subsp. denitrificans DF3 was due to a single intracellular enzyme. The soluble enzyme was purified approximately 160-fold, and the first 25 NH2-terminal amino acids were determined by automated Edman degradation. The molecular mass of the active enzyme (purity, greater than 97% as determined by amino acid sequencing) was estimated to be greater than 300,000 Da. The cyanide-hydrolyzing enzyme of A. xylosoxidans subsp. denitrificans DF3 was tentatively named cyanidase to distinguish it from known nitrilases (EC 3.5.5.1) which act on organic nitriles.
116 citations
TL;DR: In this paper, the authors modified the Natural Resources Institute's cassava cyanogen assay to overcome some of the problems encountered when the assay is applied to cassava products, such as the need for centrifugation.
Abstract: The assay for cassava cyanogens developed at the Natural Resources Institute has been modified to overcome some of the problems encountered when the assay is applied to cassava products. Inclusion of 25% ethanol in the extraction medium increased the volume of recovered extract from heat-processed cassava products, eliminated the need for centrifugation and did not interfere with any aspect of the assay. Greater cyanohydrin recovery was noted and the calculation for cyanogen contents was changed to take into account the total extract volume. The separate assay of the three cyanogens (glucosides, cyanohydrins and free cyanide) was achieved by buffering aliquots of the extract followed by appropriate treatment. The importance of assaying for free cyanide (HCN) at pH 4 was demonstrated. Above this pH, cyanohydrin degradation also produces free cyanide, giving rise to misleading values. The efficiency of the extraction medium in recovering added linamarin and cyanohydrin from cassava foods was determined. Recoveries of cyanohydrin were improved using the ethanol/acid medium.
The stability of the cyanogens in the ethanol/acid extraction medium was tested at ambient and refrigeration temperatures. Over a two-month period, refrigerated extracts showed acceptable variation as compared with normal variation within the assay (5%) for total and non-glycosidic cyanogens but the levels of free cyanide showed heavy losses (15–56% lost). Since the relative toxicities of the three cyanogens have yet to be ascertained, the relative amount of each cyanogen may be important when assessing the safety of cassava products.
114 citations
TL;DR: KpT is more stable than KpCP to H2O2, temperature, pH and urea, and it is inhibited by incubation with 3-amino-1,2,4-triazole and by the acidic forms of cyanide and azide.
77 citations
TL;DR: A Gram-positive, aerobic, endospore-forming bacterium was isolated by an enrichment technique for the ability to degrade cyanide and was identified as a Bacillus pumilus strain and rapidly degraded cyanide.
Abstract: Summary: A Gram-positive, aerobic, endospore-forming bacterium was isolated by an enrichment technique for the ability to degrade cyanide and was identified as a Bacillus pumilus strain. The bacterium rapidly degraded 100 mg I-1 of free cyanide in the absence of added inorganic and organic substances. The ability to degrade cyanide was linked to the growth phase and was not exhibited before late exponential/early stationary phase. Cyanide-degrading activity could not be induced before this time by the addition of 20 mg cyanide I-1. Production of the cyanide-degrading activity required 0.01 mg Mn2+ I-1 and did not occur at Mn2+ concentrations below 0.002 mg I-1. Cyanide-degrading activity was intracellular and cell-free extracts rapidly degraded cyanide.
76 citations
TL;DR: Previous data obtained in vivo showing that mitochondria present in dry seeds are able to synthesize ATP as soon as the seeds are rehydrated are confirmed.
Abstract: The role of mitochondria in the phosphorylation of ADP to ATP in the early steps of seed germination has been studied. Mitochondria were extracted from dry sunflower (Helianthus annuus) seeds. Adenylate kinase-dependent ATP synthesis was inhibited by p1,p5-di(adenosine-5′)pentaphosphate. Synthesis of ATP was observed with the different substrates: citrate, α-ketoglutarate, succinate, malate, pyruvate or NADH. This synthesis was activated by cytochrome c, and inhibited by cyanide, oligomycin, carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone, and carboxyatractyloside. The ATP/O values with succinate were 0.85 and 1.2 in the absence or presence, respectively, of cytochrome c. Electron micrographs showed that mitochondria of dry tissues have different structures when observed in situ or in vitro after aqueous extraction, suggesting that profound changes occurred after the contact with the aqueous medium. These results confirm previous data obtained in vivo showing that mitochondria present in dry seeds are able to synthesize ATP as soon as the seeds are rehydrated.
74 citations
TL;DR: In this article, the vibrational properties of adsorbed ions on a platinum electrode in sodium perchlorate supporting electrolyte using the nonlinear optical technique of sum frequency generation (SFG) were investigated.
62 citations
TL;DR: An Acinetobacter sp.
Abstract: An Acinetobacter sp. strain RFB1 was shown to be capable of degrading a wide range of cyano-metal complexes, simple cyanide salts and simple organic nitrile compounds. The enzymatic activity responsible for this degradation was located in an extracellular lipid complex. This complex could not be resolved into the constitutive components under standard conditions without loss of activity.
TL;DR: Transient kinetics of reduction of zucchini squash ascorbate oxidase (AO) by lumiflavin semiquinone have been studied by using laser flash photolysis, suggesting that intramolecular electron transfer probably is the rate-limiting step in enzyme catalysis.
Abstract: Transient kinetics of reduction of zucchini squash ascorbate oxidase (AO) by lumiflavin semiquinone have been studied by using laser flash photolysis. Second-order kinetics were obtained for reduction of the type I copper with a rate constant of 2.7 X 10(7) M-1 s-1, which is comparable to that obtained with other blue copper proteins such as plastocyanin. Following reduction, the type I copper was reoxidized in a protein concentration independent (i.e., intramolecular) reaction (kobs = 160 s-1). Comparison with literature values for limiting rate constants in transient single-turnover kinetic experiments suggests that intramolecular electron transfer probably is the rate-limiting step in enzyme catalysis. The extent of reoxidation of type I copper was approximately 55%, which is consistent with the approximately equal redox potentials of the type I and type III copper centers. Neither azide nor fluoride caused any significant changes in kinetics, although they are enzyme inhibitors and are thought to bind to the type II copper. In contrast, cyanide caused a concentration-dependent decrease in the extent of intramolecular electron transfer (with no change in rate constant), and decreased the rate constant for reduction of the type I copper by a factor of 2. The apparent dissociation constant for cyanide (0.2-0.4 mM) is similar to that reported for inhibition of enzyme activity. Removal of the type II copper from AO only marginally affected the kinetics of electron transfer to type I copper (k = 3.2 x 10(7) M-1 s-1) and slightly increased the extent but did not alter the rate constant of intramolecular electron transfer.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: In this article, it was shown that the cyanide stretching frequency for Ag(CN) 2 − is shifted to lower wavenumbers upon adsorption, to approximately that of Ag 4 3−.
TL;DR: Halohydrin hydrogen-halide-lyase, which catalyzes the interconversion of halohydrins to epoxides, purified from a recombinant E. coli was found to catalyze the transformation of 1,2-epoxybutane into beta-hydroxyvaleronitrile in the presence of cyanide.
Patent•
18 Dec 1991
TL;DR: Aqueous solutions which are contaminated by hydrogen sulfide, hydrogen cyanide, and ammonia are brought to a pH of about 3 or less after their formation and treated with an inert gas in a stripping column to remove the sulfide and cyanide as discussed by the authors.
Abstract: Aqueous solutions which are contaminated by hydrogen sulfide, hydrogen cyanide, and ammonia are brought to a pH of about 3 or less after their formation and treated with an inert gas in a stripping column to remove the sulfide and cyanide. The pH of the solution is then increased to about 10 or more and the solution is again treated with an inert gas in a second stripping column to remove the ammonia.
TL;DR: Upflow, anaerobic, fixed-bed, activated charcoal biotreatment columns capable of operating at free cyanide concentrations of greater than 100 mg liter-1 with a hydraulic retention time of less than 48 h were developed and strongly complexed cyanides were resistant to removal.
Abstract: Upflow, anaerobic, fixed-bed, activated charcoal biotreatment columns capable of operating at free cyanide concentrations of greater than 100 mg liter-1 with a hydraulic retention time of less than 48 h were developed. Methanogenesis was maintained under a variety of feed medium conditions which included ethanol, phenol, or methanol as the primary reduced carbon source. Under optimal conditions, greater than 70% of the inflow free cyanide was removed in the first 30% of the column height. Strongly complexed cyanides were resistant to removal. Ammonia was the nitrogen end product of cyanide transformation. In cell material removed from the charcoal columns, [14C]bicarbonate was the major carbon end product of [14C]cyanide transformation.
TL;DR: A membrane-bound nitrate reductase (nitrite:(acceptor) oxidoreductase, EC 1.7.99.4) from the extremely halophilic bacterium Haloferax denitrificans was solubilized by incubating membranes in buffer lacking NaCl and purified by DEAE, hydroxylapatite, and Sepharose 6B gel filtration chromatography.
TL;DR: A voltammetric method for determining cyanide-reactive sulfane sulfur in biological materials is described, and the thiocyanate-based procedure is preferable, particularly when samples contain either serum albumin or inorganic sulfide.
TL;DR: In this paper, anodic polarization curves have shown that excess free cyanide, used to stabilize the gold cyanide complex, poisons hydrazine oxidation on gold but not on transition metals such as nickel and cobalt.
Abstract: Hydrazine is used as a reducing agent in a novel electrodes gold plating formulation. Anodic polarization curves have shown that excess free cyanide, used to stabilize the gold cyanide complex, poisons hydrazine oxidation on gold but not on transition metals such as nickel and cobalt. This allows a new type of plating «substrate-catalyzed», which is neither immersion nor autocatalytic plating. This bath plates pure gold films at high initial rates up to 10 μm/h with exceptional bath stability and life
TL;DR: It appears that the synergistic lethal effect of simultaneous administration of carbon monoxide and cyanide are related to a precipitous decrease in blood pH, the tissue hypoxia and its resulting complications.
TL;DR: In this paper, the kinetics of replacement of 4-phenylpyridine (4-phpy) by cyanide in Fe(CN)5(4phpy)-3-naphroxymethyl cyanide (CN) was studied in various isodielectric water-cosolvent mixtures at 298 K. The experimental data are well correlated through the following equation: δΔG#exp=aδAm+bδBm+cGexc where Am, Bm and Gexc are the acidity parameter
Abstract: The kinetics of replacement of 4-phenylpyridine (4-phpy) by cyanide in Fe(CN)5(4-phpy)3– have been studied in various isodielectric water–cosolvent mixtures at 298 K. The experimental data are well correlated through the following equation: δΔG#exp=aδAm+bδBm+cGexc where Am, Bm and Gexc are the acidity parameter, the basicity parameter and the excess Gibbs free energy of the mixture, respectively. This multiparameter regression was also applied to data, taken from the literature, of substitution reactions at different pentacyanoferrate(II) complexes in order to show its general validity for explaining the effect of the medium on these types of processes in binary aqueous mixtures.
TL;DR: It is concluded that cyanide exposure induced a rapid release of endogenous glutamate mediated by both Ca( 2+)-dependent and Ca(2+)-independent mechanisms.
TL;DR: L-3-Cyanoalanine synthase activity is clearly linked to differential cyanide tolerance of two insect species, the southern armyworm and cabbage looper, and its induction becomes critical in the current explanation of differential insensitivity to cyanide.
TL;DR: This polynuclear transition metal cyanide crystallized in the cubic space group Fm3m (No. 225, O5 h), a = 10.28 I (2)A, with three formula units per cell.
Abstract: Slow diffusion of cobalt chloride with Na2[Fe(CN)5NO]-5H2O in aqueous solution produced crystals of Co[Fe(CN)5NO]-5H2O suitable for analysis by three-dimensional, single-crystal X-ray diffractometry. This polynuclear transition metal cyanide crystallized in the cubic space group Fm3m (No. 225, O5 h), a = 10.28 I (2)A, with three formula units per cell. D m = 1.67(1) Mg m−3 and D x = 1.673 Mg m−3. Final full-matrix least-squares refinement of 102 unique reflections converged to R = 0.020 and R w = 0.019. The iron nucleus is octahedrally coordinated to five cyanide ligands and a nitrosyl group and the cobalt nucleus is octahedrally coordinated to five cyanide ligands and one water molecule. Cyanide bridging (Fe-C≡N-Co) links the metal centers, providing a cubic framework within which uncoordinated water molecules occupy three crystallographically distinct environments. These uncoordinated water molecules are held in position by hydrogen bonding and/or van der Waals forces. The crystal lattice of co...
TL;DR: Inhibition by cyanide and neocuproin, but not by salicylhydroxamic acid, strongly suggests that copper is the metal involved in enzymatic urate oxidation.
TL;DR: It is proposed that formate can bind to CuB and the fast to slow transition is rationalized by using this proposal, and physical properties of the formate derivative and data for other reagents reacted with the fast-reacting enzyme preparation are presented.
Abstract: The ability to isolate preparations of cytochrome oxidase which are highly homogeneous has facilitated a study of the effects of various reagents on the purified enzyme. The addition of either sodium formate, formamide, formaldehyde, or sodium nitrite to enzyme which reacts in a single rapid kinetic phase with cyanide causes a blue-shift of 4-6 nm of the net (cytochrome a + cytochrome a3) Soret maximum. Only the derivative prepared by adding sodium formate demonstrates measurable intensity in the g' = 12 region of the low-temperature electron paramagnetic resonance (EPR) spectrum. This g' = 12 resonance is characteristic of cytochrome oxidase which has undergone a modification at the binuclear center and thereby reacts sluggishly with cyanide. As the site of cyanide binding in resting enzyme as been demonstrated to be CuB [Yoshikawa, S., & Caughey, W.S. (1990) J. Biol. Chem. 265, 7945-7958], it is proposed that formate can bind to CuB and the fast to slow transition is rationalized by using this proposal. The g' = 12 signal is also produced upon the addition of sodium formate to mitochondrial preparations, suggesting that the species responsible for this behavior may have possible physiological relevance. Physical properties of the formate derivative and data for other reagents reacted with the fast-reacting enzyme preparation are presented.
TL;DR: While physicians are concerned with nitroprusside toxicity in children, there exists no apparent consensus as to how to monitor for this toxicity and the relationship between blood cyanide or serum thiocyanate concentrations and clinical evidence of toxicity is not straightforward and requires further delineation.
Abstract: 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.
TL;DR: By utilizing a high selective reaction between silver metal and cyanide ions, an apparatus and procedure for the analytical determination of aqueous cyanide species has been developed as discussed by the authors, which has allowed for the quantitative detection of cyanide ion down to the sub-parts-per-billion level.
Abstract: By utilizing a high selective reaction between silver metal and cyanide ions, an apparatus and procedure for the analytical determination of aqueous cyanide species has been developed. This methodology has allowed for the quantitative detection of cyanide ions down to the sub-parts-per-billion level. By incorporating selective oxidation, kinetic equilibria, and photodissociation techniques, the silver-cyanide reaction technique has been adapted to provide a means of categorically speciating aqueous cyanide compounds. This detection system provides high-speed cyanide determinations with little to no sample preparation or instrument supervision