Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cyanides”

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
PubMed1987

Toxic smoke inhalation: cyanide poisoning in fire victims.

The most common cause of death in fires is the inhalation of noxious gases rather than thermal injury. Hydrogen cyanide gas, the most toxic product of combustion, seldom is recognized as a significant hazard in smoke inhalation. During the first four months of 1986, toxic amounts of cyanide were found in four of the six fatalities from house fires in Akron, Ohio. These cases illustrate the increasing frequency of cyanide poisoning in household fires. Sources of cyanide toxicity include the increased use of synthetic polymers in building materials and furnishings. Prompt recognition of and therapy for cyanide intoxication may reduce the morbidity and number of delayed deaths in fire victims. The key point in the diagnosis of cyanide poisoning is a high index of suspicion. The clinical presentation of cyanide intoxication, its diagnosis, and subsequent treatment are discussed. Finally, a prehospital protocol for treating smoke-inhalation victims who may have been exposed to cyanide gas is suggested.

Aged↗
PubMed2005

Cyanide-resistant respiration in Taenia crassiceps metacestode (cysticerci) is explained by the H2O2-producing side-reaction of respiratory complex I with O2.

The nature of the cyanide-resistant respiration of Taenia crassiceps metacestode was studied. Mitochondrial respiration with NADH as substrate was partially inhibited by rotenone, cyanide and antimycin in decreasing order of effectiveness. In contrast, respiration with succinate or ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was more sensitive to antimycin and cyanide. The saturation kinetics for O2 with NADH as substrate showed two components, which exhibited different oxygen affinities. The high-O2-affinity system (Km app=1.5 microM) was abolished by low cyanide concentration; it corresponded to cytochrome aa3. The low-O2-affinity system (Km app=120 microM) was resistant to cyanide. Similar O2 saturation kinetics, using succinate or ascorbate-TMPD as electron donor, showed only the high-O2-affinity cyanide-sensitive component. Horse cytochrome c increased 2-3 times the rate of electron flow across the cyanide-sensitive pathway and the contribution of the cyanide-resistant route became negligible. Mitochondrial NADH respiration produced significant amounts of H2O2 (at least 10% of the total O2 uptake). Bovine catalase and horse heart cytochrome c prevented the production and/or accumulation of H2O2. Production of H2O2 by endogenous respiration was detected in whole cysticerci using rhodamine as fluorescent sensor. Thus, the CN-resistant and low-O2-affinity respiration results mainly from a spurious reaction of the respiratory complex I with O2, producing H2O2. The meaning of this reaction in the microaerobic habitat of the parasite is discussed.

Animals↗
PubMed2004

Removal of cyanide by woody plants.

Hydrogen cyanide is a high volume production chemical that causes severe environmental problems. The toxicity of potassium cyanide (KCN) to basket willow trees (Salix viminalis) was tested. In aqueous solution, 2 mg CN l(-1) as KCN depressed the transpiration after 72 h about 50%. Trees exposed to 0.4 mg CN l(-1) in aqueous solution showed initially a depression of transpiration, but recovered. Doses of 8 and 20 mg CN l(-1) in aqueous solution were quickly mortal to the trees. At the end of the test, almost all cyanide had disappeared from the solutions. Levels of cyanide in plants were related to the toxicity, with no elevated levels of cyanide in plants exposed to 0.4 mg CN l(-1). Willows grown in sand survived 423.5 h irrigation with 20 mg CN l(-1). Willows grown in sand irrigated with 50 mg CN l(-1) died within a few days. The roots of the surviving willows were able to consume about 10 mg CN kg fresh weight(-1)h(-1). Vascular plants possess the enzymes beta-cyanoalanine synthase and beta-cyanoalanine hydrolase, which convert free cyanide to the amino acid asparagine. The in vivo capacity of woody plants (willow, poplar, elder, rose, birch) to remove cyanide was evaluated. Tests were performed with detached leaves and roots in KCN solutions of different concentrations. The highest removal capacity was obtained for basket willow hybrids (Salix viminalis x schwerinii). The Michaelis-Menten kinetics was determined. Realistic values of the half-saturation constant, K(M), were between 0.6 and 1.7 mg CN l(-1); the maximum metabolic capacity, v(max), was around 9.3 mg CN kg fresh weight(-1)h(-1). The removal of cyanide by plants might be useful in phytoremediation and treatment of wastewater from gold mining.

Asparagine↗
PubMed1997

Cyanide induced DNA fragmentation in mammalian cell cultures.

Cyanide is a mitochondrial poison and its toxicity is mediated through histotoxic hypoxia. Although cyanide is regarded as a neurotoxin, its other toxic manifestations are also well documented. Cyanide triggers all those events which can lead to DNA damage, but its genotoxic potential has not been established yet. The present investigation addresses the DNA damage induced by cyanide in rat thymocytes in vitro. Cell viability (eosin Y exclusion and LDH leakage) along with DNA strand breaks were measured in thymocytes exposed to 1.25-10 mM KCN for various time intervals. Cleavage into oligonucleosomal fragments of extracted DNA from cyanide treated thymocytes were visualized on gel electrophoresis. Cyanide produced both time and dose dependent DNA fragmentation accompanied by cytotoxicity. The DNA damage was sensitive to elevated levels of extracellular Ca2+ and was minimal in Ca2+ free medium. The DNA fragmentation was attenuated by Zn2+ (modulator of Ca2+/Mg2+-dependent endonuclease), N-acetylcysteine (free radical scavenger) and diltiazem (Ca2+ channel blocker). Cyanide induced DNA damage was further observed in baby hamster kidney cells (BHK-21), where unlike thymocytes, internucleosomal DNA fragmentation was not observed. Thymocytes were more sensitive to cyanide as compared to BHK-21 cells.

Animals↗
PubMed2001

Diagnosis of cyanide intoxication by measurement of cytochrome c oxidase activity.

Cytochrome c oxidase (CCO), a mitochondrial enzyme, is inactivated by cyanide or carbon monoxide (CO) intoxication. We measured CCO activity, in the major organs of the rat at various times after death caused by cyanide intoxication. Tissue samples were homogenized, and the CCO activity in the mitochondrial fraction was measured using ferrous cytochrome c as the substrate. The CCO activity inhibition was highest in the brain, although the cyanide concentration was lowest level. As a result of this and the clinical symptoms displayed, we consider the brain to be the primary organ of cyanide intoxication. As cyanide is highly toxic to humans, in small amounts and many patients and victims have already had some medical care, it is difficult to detect cyanide in criminal investigations. The CCO activities in various organs remained significantly low for 2 days after the cyanide intoxication, suggesting that the diagnosis may be possible by measuring not only the cyanide concentration but also the CCO activity.

Animals↗
PubMed1997

Reactive oxygen species generated by cyanide mediate toxicity in rat pheochromocytoma cells.

Peroxide formation has been implicated in impairment of motor function by cyanide which occurs in both animals and man. The present study employs the neuronal model, rat pheochromocytoma (PC12) cells to evaluate peroxidation as a toxic mechanism of cyanide. Confocal imaging shows that peroxides form within a few seconds in cell cytoplasm after cyanide exposure and continue to accumulate over a period of several minutes. Peroxide generation by cyanide is decreased to about 50% by phospholipase A2 inhibitors indicating involvement of arachidonic acid in the oxidative process. Also antioxidant defense enzymes (CuZn superoxide dismutase and especially catalase) in PC12 cells are inhibited by cyanide. It appears that peroxide accumulation after cyanide treatment involves both inhibition of breakdown and increased production. Furthermore, both peroxide accumulation and cell death induced by cyanide in PC12 cells are blocked by an antioxidant (ascorbate). These data support the hypothesis that the cytotoxic action of cyanide is related in part to an oxidative process.

Amitrole↗
PubMed1989

Improved gas chromatography with electron-capture detection using a reaction pre-column for the determination of blood cyanide: a higher content in the left ventricle of fire victims.

We developed a head-space method for the determination of blood cyanide by gas chromatography with electron-capture detection. In this technique, a reaction pre-column, packed with chloramine-T, was used for the conversion of hydrogen cyanide into cyanogen chloride. Since the reaction pre-column eliminated the necessity for trapping hydrogen cyanide from the biological samples, blood cyanide was quickly analysed by acidification only. The reaction pre-column was durable for at least several months. The calibration curve gave good linearity when dichloromethane was used as the internal standard, and the lower detection limit taken from this plot was ca. 0.05 micrograms/ml. The relative standard deviation of spiked blood samples was in the range 0.6-3.9%. We determined blood cyanide levels at autopsy in victims who had died from fire using this method. A significantly higher cyanide content was detected in the left ventricular blood than in the right. There was a positive correlation between blood cyanide and carboxylhaemoglobin contents. This simple and sensitive technique could be very useful for the determination of cyanide in various samples.

Autopsy↗
PubMed1998

Cyanide exposure affects the production and excretion of ammonia by the mudskipper Boleophthalmus boddaerti.

The concentrations of ammonia in the plasma of the mudskipper Boleophthalmus boddaerti exposed to cyanide for 1-6 days were significantly greater than the respective values of the controls. This was due to an increase in the production of NH3 in the muscle and an increase in the retention of NH3 and/or NH4+ in the blood of the cyanide-exposed fish when compared to controls. Cyanide exposure significantly increased the specific activity of muscle AMP deaminase. Since adenylosuccinate synthetase and lyase were also present in the muscle, exposure to cyanide might increase the production of NH3 from the catabolism of purine nucleotides. B. boddaerti exposed to cyanide excreted significantly less ammonia than the control fish. Results indicate changes in the permeability of the epithelial surfaces of the cyanide-exposed fish to NH3 and/or NH4+. Since the tissues and organs needed time to activate the inducible cyanide detoxification mechanisms, the increase in the production of NH3 might be an important defensive mechanism for B. boddaerti during the early phase of cyanide exposure.

AMP Deaminase↗
PubMed1993

Fourier-transform infrared study of cyanide binding to the Fea3-CuB binuclear site of bovine heart cytochrome c oxidase: implication of the redox-linked conformational change at the binuclear site.

Cyanide binding to the Fea3-CuB binuclear center of cytochrome c oxidase purified from bovine heart mitochondria was examined by Fourier-transform infrared spectroscopy. In the fully oxidized state, cyanide binding caused an appearance of a sharp infrared C-N stretching band at 2152 cm-1. This 2152-cm-1 band was assigned to a bridging structure, Fea3(3+)-C-N-CuB2+, on the basis of the isotope replacement experiments. The bound cyanide giving the 2152-cm-1 band was hardly exchangeable with an exogenous ligand added afterward in the fully oxidized state and, upon partial reduction, was converted specifically to the 2132-cm-1 band species assignable to Fea3(3+)-C-N. The reduction of the Fea3 center resulted in appearances of two new infrared bands at 2058 and 2045 cm-1 concomitantly. At higher concentration of cyanide (> 5 mM) an additional two infrared bands appeared at 2093 and 2037 cm-1. The former two bands are assignable to the Fea3(2+)-bound cyanides, whereas the latter two bands are possibly due to the CuB(1+)-bound cyanides on the basis of the competition experiments using carbon monoxide. These observations suggest that there are three kinds of conformational change to occur at the Fea3-CuB binuclear site upon reduction of the metal centers. The first one occurs upon reduction of the CuB center, and the second one occurs upon reduction of the Fea and/or CuA centers. These are associated with the "closed" to "open" conformational transition characterized by the disappearance of the 2152-cm-1 band and the appearance of the 2132- and 2093-cm-1 bands. The third one can be induced upon reduction of the Fea3 center, and this enables the binding of a second cyanide to the CuB(1+)-CN center, at a higher concentration of cyanide, being oriented toward the Fea3(2+) center to produce the 2037-cm-1 band. These structural changes at the Fea3-CuB binuclear site controlled by the redox levels of the metal centers may provide a functional role(s) for the cytochrome c oxidase-catalyzed reactions, such as the reduction of dioxygen to water and the vectorial proton pumping across the mitochondrial inner membrane.

Animals↗
PubMed2004

Cyanide binding to hexacoordinate cyanobacterial hemoglobins: hydrogen-bonding network and heme pocket rearrangement in ferric H117A Synechocystis hemoglobin.

The truncated hemoglobin (Hb) from the cyanobacterium Synechocystis sp. PCC 6803 is a bis-histidyl hexacoordinate complex in the absence of exogenous ligands. This protein can form a covalent cross-link between His117 in the H-helix and the heme 2-vinyl group. Cross-linking, the physiological importance of which has not been established, is avoided with the His117Ala substitution. In the present work, H117A Hb was used to explore exogenous ligand binding to the heme group. NMR and thermal denaturation data showed that the replacement was of little consequence to the structural and thermodynamic properties of ferric Synechocystis Hb. It did, however, decelerate the association of cyanide ions with the heme iron. Full complexation required hours, instead of minutes, of incubation at optical and NMR concentrations. At neutral pH and in the presence of excess cyanide, binding occurred with a first-order dependence on cyanide concentration, eliminating distal histidine decoordination as the rate-limiting step. The cyanide complex of the H117A variant was characterized for the conformational changes occurring as the histidine on the distal side, His46 (E10), was displaced. Extensive rearrangement allowed Tyr22 (B10) to insert in the heme pocket and Gln43 (E7) and Gln47 (E11) to come in contact with it. H-bond formation to the bound cyanide was identified in solution with the use of (1)H(2)O/(2)H(2)O mixtures. Cyanide binding also resulted in a change in the ratio of heme orientational isomers, in a likely manifestation of heme environment reshaping. Similar observations were made with the related Synechococcus sp. PCC 7002 H117A Hb, except that cyanide binding was rapid in this protein. In both cases, the (15)N chemical shift of bound cyanide was reminiscent of that in peroxidases and the orientation of the proximal histidine was as in other truncated Hbs. The ensemble of the data provided insight into the structural cooperativity of the heme pocket scaffold and pointed to the reactive 117 site of Synechocystis Hb as a potential determinant of biophysical and, perhaps, functional properties.

Alanine↗
PubMed2001

Hydroxocobalamin: improved public health readiness for cyanide disasters.

The United States is under the constant threat of a mass casualty cyanide disaster from industrial accidents, hazardous material transportation incidents, and deliberate terrorist attacks. The current readiness for cyanide disaster by the emergency medical system in the United States is abysmal. We, as a nation, are simply not prepared for a significant cyanide-related event. The standard of care for cyanide intoxication is the cyanide antidote kit, which is based on the use of nitrites to induce methemoglobinemia. This kit is both expensive and ill suited for out-of-hospital use. It also has its own inherent toxicity that prevents rapid administration. Furthermore, our hospitals frequently fail to stock this life-saving antidote or decline to stock more than one. Hydroxocobalamin is well recognized as an efficacious, safe, and easily administered cyanide antidote. Because of its extremely low adverse effect profile, it is ideal for out-of-hospital use in suspected cyanide intoxication. To effectively prepare for a cyanide disaster, the United States must investigate, adopt, manufacture, and stockpile hydroxocobalamin to prevent needless morbidity and mortality.

Accidents, Occupational↗
PubMed2006

Parameter estimation of a plant uptake model for cyanide: application to hydroponic data.

A plant uptake model is applied to describe free cyanide and ferrocyanide transport and fate in willow (Salix eriocephala var. Michaux) grown in hydroponics. The model is applied to experimental data to determine best-fit parameter values, their associated uncertainty, and their relative importance to field-scale phytoremediation applications. The fitted model results, using least-squares optimization of the observed log concentrations, indicate that free cyanide volatilization from leaf tissue and free cyanide cell wall adsorption were negligible. The free cyanide maximum uptake rate and assimilate (noncyanide 15N) first-order leaf loss rate were the only coefficients that significantly affected the model goodness of fit and were concurrently sensitive to data uncertainty in the parameter optimization. Saturation kinetics may be applicable for free cyanide uptake into plants, but not for ferrocyanide uptake, which may occur via preferential protein-mediated or inefficient transpiration stream uptake. Within the free cyanide system, the relative magnitudes of the saturation uptake parameters and the demonstration of an active role for plants in uptake relative to transpiration suggest the potential importance of preferential diffusion through the cell membranes as reported in the literature, rather than protein-mediated uptake. The fitted 13-parameter model matched the observed data well except for the predicted stem and leaf tissue assimilate concentrations, which were significantly underestimated, particularly in the free cyanide system. These low predicted values, combined with the slightly underestimated solution free cyanide removal, suggest that noncyanide 15N redistribution in phloem should be considered.

Biodegradation, Environmental↗
PubMed1981

The effect of cyanide on serum cobalamin and on cobalamin analogues when measured by radioassay using R-protein and intrinsic factor.

Concentrations of cobalamin measured in human serum by radioassay differ when R-protein or intrinsic factor is used as the binding determinant. Experiments were carried out to determine whether the concentration of cyanide used to extract the serum cobalamin could account for this difference. When either R-protein or intrinsic factor was used, the cobalamin measured in serum extracted in the absence of cyanide was low. As the concentration of cyanide was raised in the extraction mixture, the cobalamin concentration that was measured increased when either protein binder was used, but the absolute increase was greater with R-protein. R-protein or intrinsic-factor-reactive cobalamin could be recovered from serum proteins precipitated in the absence of cyanide and reextracted in the presence of cyanide. There was low recovery of hydroxo, methyl, or adenosyl cobalamins added to serum when the serum was extracted in the absence of cyanide, but recovery was quantitative when using either protein binder with cyanide in the extraction step. With 0.25 microgram of potassium cyanide/ml of extraction mixture and R-protein as the binding determinant in the radioassay, sera with normal, moderately low, and very low cobalamin concentrations could by separated. These experiments indicate that the concentration of cyanide used to extract cobalamin from the serum may account for some but not all of the differences observed when R-protein and intrinsic factor are used in the radioassay. The range of normal and low serum cobalamin are method-dependent and must be established by each laboratory for the radioassay procedure used.

Binding Sites↗
PubMed1977

Inhibition of mitochondrial respiration by sodium nitroprusside and the mechanism of cyanide liberation.

The influence of sodium nitroprusside (SNP) on mitochondrial respiration was examined in rat liver mitochondria. The addition of SNP 1 mmol litre-1 during state 3 respiration inhibited the oxygen uptake by 63.4%. A mixture of SNP 1 mmol litre-1 and glutathione (GSH) 1 mmol litre-1 inhibited the oxygen uptake more markedly (by 75.9%). The cyanide concentrations were 0.01 mmol litre-1 with SNP alone and 0.15 mmol litre-1 with the mixture of SNP and GSH. Cyanide production from SNP in the presence of various reducing agents was studied in potassium phosphate 0.1 mol litre-1 buffer solution (pH 7.4) incubated at 37 degrees C. Cyanide was liberated markedly from SNP in the presence of GSH or ascorbate. Less cyanide was produced in the presence of NADH or NADPH. The rate of production of cyanide was dependent entirely upon the concentration of each reducing agent added. No cyanide was liberated when sodium dithionite or the oxidized forms of GSH, NAD or NADP were used. It was concluded that SNP is degradated to cyanide by a hydrogen donor and that the cyanide liberated in this manner inhibits the cytochrome oxidase activity of mitochondria in vivo.

Animals↗
PubMed2002

Value of lactic acidosis in the assessment of the severity of acute cyanide poisoning.

OBJECTIVE: To test the hypothesis that plasma lactate concentrations could be of confirmatory value in patients with histories consistent with acute pure cyanide poisoning because immediate laboratory confirmation of suspected cyanide poisoning is rarely possible and because clinicians must rapidly decide whether to administer specific antidotes, which may have severe side effects. DESIGN: Retrospective clinical study. SETTING: An intensive care unit in a university-affiliated teaching hospital. PATIENTS: All acute cyanide-poisoned patients admitted to our intensive care unit, excluding fire victims, from 1988 to 1999. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Eleven patients were studied. Before antidotal treatment, the median plasma lactate concentration was 168 mg/dL, the median blood cyanide concentration was 4.2 mg/L. Using Spearman's test, there was a significant correlation between plasma lactate and blood cyanide concentrations ( =.74, =.017). Before antidotal treatment, plasma lactate concentration correlated positively with anion gap and inversely with systolic blood pressure, spontaneous respiratory rate, and arterial pH. During the course of cyanide poisonings, a plasma lactate concentration of >or=72 mg/d/L (8 mmol/L) was sensitive (94%) and moderately specific (70%) for a toxic blood cyanide concentration (>or=1.0 mg/L). The specificity was substantially improved in patients not receiving catecholamines (85%). CONCLUSIONS: The immediate and serial measurement of plasma lactate concentrations is useful in assessing the severity of cyanide poisoning.

Adolescent↗
PubMed1991

An efficient cyanide-degrading Bacillus pumilus strain.

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 l-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 l-1. Production of the cyanide-degrading activity required 0.01 mg Mn2+ l-1 and did not occur at Mn2+ concentrations below 0.002 mg l-1. Cyanide-degrading activity was intracellular and cell-free extracts rapidly degraded cyanide.

Bacillus↗
PubMed2006

The redox couple of the cytochrome c cyanide complex: the contribution of heme iron ligation to the structural stability, chemical reactivity, and physiological behavior of horse cytochrome c.

Contrary to most heme proteins, ferrous cytochrome c does not bind ligands such as cyanide and CO. In order to quantify this observation, the redox potential of the ferric/ferrous cytochrome c-cyanide redox couple was determined for the first time by cyclic voltammetry. Its E0' was -240 mV versus SHE, equivalent to -23.2 kJ/mol. The entropy of reaction for the reduction of the cyanide complex was also determined. From a thermodynamic cycle that included this new value for the cyt c cyanide complex E0', the binding constant of cyanide to the reduced protein was estimated to be 4.7 x 10(-3) L M(-1) or 13.4 kJ/mol (3.2 kcal/mol), which is 48.1 kJ/mol (11.5 kcal/mol) less favorable than the binding of cyanide to ferricytochrome c. For coordination of cyanide to ferrocytochrome c, the entropy change was earlier experimentally evaluated as 92.4 J mol(-1) K(-1) (22.1 e.u.) at 25 K, and the enthalpy change for the same net reaction was calculated to be 41.0 kJ/mol (9.8 kcal/mol). By taking these results into account, it was discovered that the major obstacle to cyanide coordination to ferrocytochrome c is enthalpic, due to the greater compactness of the reduced molecule or, alternatively, to a lower rate of conformational fluctuation caused by solvation, electrostatic, and structural factors. The biophysical consequences of the large difference in the stabilities of the closed crevice structures are discussed.

Animals↗
PubMed1982

Mechanistic implications of cyanide binding to carboxypeptidase B.

The putative metal coordinating ligand cyanide was used to study the effects of modifications of the metal coordination sphere on the spectral properties and catalytic activity of cobalt and zinc carboxypeptidases. The absorption spectra of Co2+-carboxypeptidase B in the presence of cyanide pointed to a direct interaction of the ligands with the metal. Gel-filtration experiments showed that the binding of one mole of ligand per mole of enzyme metal ion resulted in maximal spectral effects. Binding of cyanide to the metal ion as measured by absorption spectroscopy was inhibited by acetyl-L-arginine, a peptide pseudosubstrate, and by acetyl-D-arginine, a competitive peptide inhibitor. Addition of acetyl arginine to the enzyme-cyanide complex caused displacement of the ligand, as evidenced by the spectral parameters. Cyanide inhibited peptide hydrolysis in a partially noncompetitive manner, i.e. it did not prevent binding of the substrate to the enzyme but the enzyme-substrate-cyanide complex was hydrolyzed at a slower rate than the enzyme-substrate complex. The dissociation constant evaluated from kinetic studies for the binding of cyanide to Co2+-carboxypeptidase B was in good agreement with that obtained from spectral measurements. Hydrolysis of the ester analog of the basis peptide substrate was not affected by cyanide. Based on these data a model is proposed in which the peptide carboxyl group displaces the water molecule from the metal coordination sphere during catalysis without increasing the coordination number.

Animals↗