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Toxicology and Applied Pharmacology Aug 2007Uncoupling protein 2 (UCP-2) is an inner mitochondrial membrane proton carrier that modulates mitochondrial membrane potential (DeltaPsi(m)) and uncouples oxidative...
Uncoupling protein 2 (UCP-2) is an inner mitochondrial membrane proton carrier that modulates mitochondrial membrane potential (DeltaPsi(m)) and uncouples oxidative phosphorylation. We have shown that up-regulation of UCP-2 by Wy14,643, a selective peroxisome proliferator-activated receptor-alpha (PPARalpha) agonist, enhances cyanide cytotoxicity. The pathway by which Wy14,643 up-regulates UCP-2 was determined in a dopaminergic cell line (N27 cells). Since dopaminergic mesencephalic cells are a primary brain target of cyanide, the N27 immortalized mesencephalic cell was used in this study. Wy14,643 produced a concentration- and time-dependent up-regulation of UCP-2 that was linked to enhanced cyanide-induced cell death. MK886 (PPARalpha antagonist) or PPARalpha knock-down by RNA interference (RNAi) inhibited PPARalpha activity as shown by the peroxisome proliferator response element-luciferase reporter assay, but only partially decreased up-regulation of UCP-2. The role of oxidative stress as an alternative pathway to UCP-2 up-regulation was determined. Wy14,643 induced a rapid surge of ROS generation and loading cells with glutathione ethyl ester (GSH-EE) or pre-treatment with vitamin E attenuated up-regulation of UCP-2. On the other hand, RNAi knockdown of PPARalpha did not alter ROS generation, suggesting a PPARalpha-independent component to the response. Co-treatment with PPARalpha-RNAi and GSH-EE blocked both the up-regulation of UCP-2 by Wy14,643 and the cyanide-induced cell death. It was concluded that a PPARalpha-mediated pathway and an oxidative stress pathway independent of PPARalpha mediate the up-regulation of UCP-2 and subsequent increased vulnerability to cyanide-induced cytotoxicity.
Topics: Animals; Cell Line, Transformed; Cell Survival; Dose-Response Relationship, Drug; Drug Combinations; Drug Interactions; Enzyme Inhibitors; Gene Silencing; Glutathione; Indoles; Ion Channels; Mitochondria; Mitochondrial Proteins; Neurons; Oxidative Stress; PPAR alpha; Potassium Cyanide; Pyrimidines; Rats; Reactive Oxygen Species; Uncoupling Protein 2; Up-Regulation; Vitamin E
PubMed: 17573087
DOI: 10.1016/j.taap.2007.05.002 -
Veterinary Research 2003The present work was aimed at evaluating the effects of maternal exposure to potassium cyanide (KCN) during lactation in goats. Twenty-seven lactating female goats were...
The present work was aimed at evaluating the effects of maternal exposure to potassium cyanide (KCN) during lactation in goats. Twenty-seven lactating female goats were orally dosed with 0 (control), 1.0, 2.0, or 3.0 mg KCN/kg body weight/day from lactation days 0 to 90. After this period, all male kids and one mother from each group were killed for a pathological study. Cyanide treatment promoted the clinical signs of maternal toxicity in the highest KCN group but did not affect body weight. Both cyanide and thiocyanate presented increased levels in both dams and kids from the treated groups. Microscopic lesions, but without alterations on the biochemical panel, were found in the brain, thyroid, liver, and kidneys of both dams and kids from the treated groups. These findings suggest that lactating offspring can be indirectly intoxicated by maternal exposure to cyanide.
Topics: Animals; Animals, Suckling; Brain; Brain Chemistry; Female; Goats; Kidney; Lactation; Liver; Male; Maternal Exposure; Milk; Potassium Cyanide; Thiocyanates; Thyroid Gland; Time Factors
PubMed: 12657213
DOI: 10.1051/vetres:2002068 -
The Journal of Biological Chemistry Jul 1993Cyclosporin A (CyA) and L-carnitine (LC) prevented the killing of cultured hepatocytes by anoxia and rotenone but not by cyanide. Neither CyA nor LC affected the rate or...
Cyclosporin A (CyA) and L-carnitine (LC) prevented the killing of cultured hepatocytes by anoxia and rotenone but not by cyanide. Neither CyA nor LC affected the rate or extent of the loss of the mitochondrial membrane potential or the rate or extent of the depletion of ATP. Atractyloside blocked the ability of both CyA and LC to protect, and D-carnitine antagonized the effect of LC but not that of CyA. Cell killing by cyanide was prevented when the phospholipase A2 inhibitor butacaine was added together with CyA. Butacaine by itself had no effect on cell killing. In a swelling assay with isolated rat liver mitochondria having a low calcium content, phenylarsine oxide or palmitoyl-CoA induced the inner membrane permeability transition when electron transport was inhibited by rotenone or cyanide. CyA prevented the permeability transition with rotenone but not with cyanide, and atractyloside reversed the effect of CyA. LC prevented the permeability transition occurring with palmitoyl-CoA plus rotenone but not with palmitoyl-CoA plus cyanide. Atractyloside and D-carnitine antagonized the protective effect of LC. Inhibition of the cyanide-dependent permeability transition in isolated liver mitochondria required the presence of both CyA and butacaine. These data document the close correlation between the effect of CyA and LC on the response of cultured hepatocytes to inhibition of mitochondrial electron transport and their ability to prevent the permeability transition in isolated mitochondria. It is concluded that the ability of CyA and LC to protect cultured hepatocytes is a consequence of their ability to prevent the mitochondrial permeability transition, indicating that this event is likely to be causally linked to the genesis of irreversible injury. Thus, cell death with anoxia or inhibitors of electron transport is related to a mitochondrial alteration by a mechanism that is independent of the maintenance of a membrane potential or cellular stores of ATP.
Topics: 4-Aminobenzoic Acid; Aminobenzoates; Animals; Arsenicals; Atractyloside; Carnitine; Cell Death; Cell Hypoxia; Cells, Cultured; Cyclosporine; Intracellular Membranes; Kinetics; Liver; Male; Membrane Potentials; Mitochondria, Liver; Permeability; Potassium Cyanide; Rats; Rats, Sprague-Dawley; Rotenone; Time Factors; para-Aminobenzoates
PubMed: 8314748
DOI: No ID Found -
The Journal of Pharmacology and... Jan 2010Cyanide is a potent neurotoxicant that can produce dopaminergic neuronal death in the substantia nigra and is associated with a Parkinson-like syndrome. In this study...
Cyanide is a potent neurotoxicant that can produce dopaminergic neuronal death in the substantia nigra and is associated with a Parkinson-like syndrome. In this study involvement of Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3), a BH3-only Bcl-2 protein, in cyanide-induced death of dopaminergic cells was determined in mice and Mes 23.5 cells. Treatment of mice with cyanide up-regulated BNIP3 and Bax expression in tyrosine hydroxylase (TH)-positive cells of the substantia nigra, and progressive loss of TH-positive neurons was observed over a 9-day period. In Mes 23.5 dopaminergic cells, cyanide stimulated translocalization of BNIP3 to both endoplasmic reticulum (ER) and mitochondria. In ER, BNIP3 stimulated release of Ca(2+) into the cytosol, followed by accumulation of mitochondrial Ca(2+), resulting in reduction of mitochondrial membrane potential (Deltapsi(m)) and eventually cell death. Cyanide also activated Bax to colocalize with BNIP3 in ER and mitochondria. Forced overexpression of BNIP3 activated Bax, whereas gene silencing reduced Bax activity. Knockdown of Bax expression by small interfering RNA blocked the BNIP3-mediated changes in ER and mitochondrial Ca(2+) to block cyanide-induced mitochondrial dysfunction and cell death. These findings show that BNIP3-mediates cyanide-induced dopaminergic cell death through a Bax downstream signal that mobilizes ER Ca(2+) stores, followed by mitochondrial Ca(2+) overload.
Topics: Animals; Apoptosis; Brain; Calcium; Cell Line; Dopamine; Endoplasmic Reticulum; Male; Membrane Potential, Mitochondrial; Membrane Proteins; Mice; Mitochondria; Mitochondrial Proteins; Potassium Cyanide; RNA, Small Interfering; Up-Regulation; bcl-2-Associated X Protein
PubMed: 19841471
DOI: 10.1124/jpet.109.159103 -
Metabolism: Clinical and Experimental Mar 2001Whether or not to apply nutritional pretreatment and how to do so are controversial issues with respect to the liver about to undergo aggressive intervention. We studied...
Whether or not to apply nutritional pretreatment and how to do so are controversial issues with respect to the liver about to undergo aggressive intervention. We studied the effects of glucose loading on the viability of hepatocytes that were subsequently exposed to the inhibitors of carbohydrate metabolism, potassium cyanide (KCN) and iodoacetic acid (IAA). After rat hepatocytes were cultured for 24 hours in Leibovitz's L-15 medium containing 0, 10, 20, and 30 mmol/L glucose, the medium was replaced with modified Hanks-HEPES buffer with or without 2.5 mmol/L KCN or 0.5 mmol/L IAA. Lactate dehydrogenase (LDH) activity, lactate concentration, and pH of the supernatant were measured after 0, 2, 4, and 6 hours of exposure to KCN and after 0, 20, 40, and 60 minutes of exposure to IAA. Glycogen and adenosine triphosphate (ATP) contents in the hepatocytes were measured simultaneously. Hepatocytes cultured with various concentrations of glucose for 24 hours stored levels of glycogen in proportion to the glucose concentration in the culture medium without any significant difference in viability. The hepatocytes cultured with higher glucose concentrations maintained a higher ATP content and released less LDH and more lactate, and the pH decreased in the supernatant during exposure to KCN. Conversely, hepatocytes cultured with lower glucose concentrations maintained a higher ATP content and released less LDH during exposure to IAA. In conclusion, prior glucose loading appears to be beneficial for hepatocytes if oxidative phosphorylation is to be inhibited, whereas withholding glucose appears to be beneficial if glycolysis is to be inhibited.
Topics: Adenosine Triphosphate; Animals; Cell Survival; Cells, Cultured; Enzyme Inhibitors; Extracellular Space; Glucose; Glycogen; Hepatocytes; Hydrogen-Ion Concentration; Iodoacetic Acid; L-Lactate Dehydrogenase; Lactic Acid; Male; Poisons; Potassium Cyanide; Rats; Rats, Wistar
PubMed: 11230789
DOI: 10.1053/meta.2001.20204 -
Indian Journal of Anaesthesia May 2014A 30-year-old male jewellery factory worker accidentally ingested silver potassium cyanide and was brought to the emergency department in a state of shock and profound...
A 30-year-old male jewellery factory worker accidentally ingested silver potassium cyanide and was brought to the emergency department in a state of shock and profound metabolic acidosis. This patient was managed hypothetically with use of injection thiopentone sodium intravenously until the antidote was received. Cyanide is a highly cytotoxic poison and it rapidly reacts with the trivalent iron of cytochrome oxidase thus paralysing the aerobic respiration. The result is severe lactic acidosis, profound shock, and its fatal outcome. The patient dies of cardio-respiratory arrest secondary to dysfunction of the medullary centres. It is rapidly absorbed, symptoms begin few seconds after exposure and death usually occurs in <30 min. The average lethal dose for potassium cyanide is about 250 mg. We used repeated doses of thiopentone sodium till the antidote kit was finally in our hands, hypothesising that it contains thiol group similar to the antidote thiosulphate. Moreover, it is an anticonvulsant. We were successful in our attempts and the patient survived though the specific antidotes could be administered after about an hour.
PubMed: 25024476
DOI: 10.4103/0019-5049.135045 -
Journal of Bacteriology Apr 1987Free-living Bradyrhizobium japonicum grown heterotrophically with 1 microM 63Ni2+ accumulated label. Strain SR470, a Hupc mutant, accumulated almost 10-fold more 63Ni2+...
Free-living Bradyrhizobium japonicum grown heterotrophically with 1 microM 63Ni2+ accumulated label. Strain SR470, a Hupc mutant, accumulated almost 10-fold more 63Ni2+ on a per-cell basis than did strain SR, the wild type. Nongrowing cells were also able to accumulate nickel over a 2-h period, with the Hupc mutant strain SR470 again accumulating significantly more 63Ni2+ than strain SR. These results suggest that this mutant is constitutive for nickel uptake as well as for hydrogenase expression. The apparent Kms for nickel uptake in strain SR and strain SR470 were found to be similar, approximately 26 and 50 microM, respectively. The Vmax values, however, were significantly different, 0.29 nmol of Ni/min per 10(8) cells for SR and 1.40 nmol of Ni/min per 10(8) cells for SR470. The uptake process was relatively specific for nickel; only Cu2+ and Zn2+ (10 microM) were found to appreciably inhibit the uptake of 1 microM Ni, while a 10-fold excess of Mg2+, Co2+, Fe3+, or Mn2+ did not affect Ni2+ uptake. The lack of inhibition by Mg2+ indicates that nickel is not transported by a magnesium uptake system. Nickel uptake was also inhibited by cold (53% inhibition at 4 degrees C) and slightly by the ionophores nigericin and carbonyl cyanide m-chlorophenylhydrazone. Other ionophores did not appreciably affect nickel uptake, even though they significantly stimulated O2 uptake. The cytochrome c oxidase inhibitors azide, cyanide, and hydroxylamine did not inhibit Ni2+ uptake, even at concentrations (of cyanide and hydroxylamine) that inhibited O2 uptake. The addition of oxidizable substrates such as succinate or gluconate did not increase nickel uptake, even though they increased respiratory activity. Nickel update showed a pH dependence with an optimum at 6.0. Most (approximately 85%) of the 63Ni2+ taken up in 1 min by strain SR470 was not exchangeable with cold nickel.
Topics: Biological Transport; Copper; Hydrogen-Ion Concentration; Hydroxylamine; Hydroxylamines; Ionophores; Kinetics; Magnesium; Nickel; Potassium Cyanide; Rhizobiaceae; Valinomycin; Zinc
PubMed: 3558318
DOI: 10.1128/jb.169.4.1398-1402.1987 -
Neural Regeneration Research Sep 2014Flavonoids from the stems and leaves of Scutellaria baicalensis Georgi, an antioxidant, markedly improve memory impairments and neuronal injuries. In the present study,...
Flavonoids from the stems and leaves of Scutellaria baicalensis Georgi, an antioxidant, markedly improve memory impairments and neuronal injuries. In the present study, primary cortical neurons of rats were exposed to potassium cyanide to establish a model of in vitro neural cell apoptosis. Inhibition of apoptosis by flavonoids from the stems and leaves of Scutellaria baicalensis Georgi at concentrations of 18.98, 37.36, and 75.92 μg/mL was detected using this model. These flavonoids dramatically increased cell survival, inhibited cell apoptosis and excessive production of malondialdehyde, and increased the activities of superoxide dismutase, glutathione peroxidase, and Na(+)-K(+)-ATPase in primary cortical neurons exposed to potassium cyanide. The flavonoids from the stems and leaves of Scutellaria baicalensis Georgi were originally found to have a polyhydric structure and to protect against cerebral hypoxia in in vitro and in vivo models, including hypoxia induced by potassium cyanide or cerebral ischemia. The present study suggests that flavonoids from the stems and leaves of Scutellaria baicalensis Georgi exert neuroprotective effects via modulation of oxidative stress, such as malondialdehyde, superoxide dismutase, glutathione peroxidase and Na(+)-K(+)-ATPase disorders induced by potassium cyanide.
PubMed: 25368645
DOI: 10.4103/1673-5374.141784 -
Journal of Bacteriology Oct 1993A cyanide-degrading enzyme from Bacillus pumilus C1 has been purified and characterized. This enzyme consisted of three polypeptides of 45.6, 44.6, and 41.2 kDa; the...
A cyanide-degrading enzyme from Bacillus pumilus C1 has been purified and characterized. This enzyme consisted of three polypeptides of 45.6, 44.6, and 41.2 kDa; the molecular mass by gel filtration was 417 kDa. Electron microscopy revealed a multimeric, rod-shaped protein approximately 9 by 50 nm. Cyanide was rapidly degraded to formate and ammonia. Enzyme activity was optimal at 37 degrees C and pH 7.8 to 8.0. Activity was enhanced by Sc3+, Cr3+, Fe3+, and Tb3+; enhancement was independent of metal ion concentration at concentrations above 5 microM. Reversible enhancement of enzymatic activity by azide was maximal at 4.5 mM azide and increased with time. No activity was recorded with the cyanide substrate analogs CNO-, SCN-, CH3CN, and N3- and the possible degradation intermediate HCONH2. Kinetic studies indicated a Km of 2.56 +/- 0.48 mM for cyanide and a Vmax of 88.03 +/- 4.67 mmol of cyanide per min/mg/liter. The Km increased approximately twofold in the presence of 10 microM Cr3+ to 5.28 +/- 0.38 mM for cyanide, and the Vmax increased to 197.11 +/- 8.51 mmol of cyanide per min/mg/liter. We propose naming this enzyme cyanide dihydratase.
Topics: Bacillus; Cations, Divalent; Centrifugation, Density Gradient; Chromatography, DEAE-Cellulose; Chromatography, Gel; Electrophoresis, Polyacrylamide Gel; Hydrolases; Kinetics; Macromolecular Substances; Manganese; Microscopy, Electron; Molecular Weight; Potassium Cyanide; Thermodynamics
PubMed: 8407782
DOI: 10.1128/jb.175.19.6105-6112.1993 -
PloS One 2018Cyanide is a potent toxic agent, and the few available antidotes are not amenable to rapid deployment in mass exposures. As a result, there are ongoing efforts to...
Cyanide is a potent toxic agent, and the few available antidotes are not amenable to rapid deployment in mass exposures. As a result, there are ongoing efforts to exploit different animal models to identify novel countermeasures. We have created a pipeline that combines high-throughput screening in zebrafish with subsequent validation in two mammalian small animal models as well as a porcine large animal model. We found that zebrafish embryos in the first 3 days post fertilization (dpf) are highly resistant to cyanide, becoming progressively more sensitive thereafter. Unbiased analysis of gene expression in response to several hours of ultimately lethal doses of cyanide in both 1 and 7 dpf zebrafish revealed modest changes in iron-related proteins associated with the age-dependent cyanide resistance. Metabolomics measurements demonstrated significant age-dependent differences in energy metabolism during cyanide exposure which prompted us to test modulators of the tricarboxylic acid cycle and related metabolic processes as potential antidotes. In cyanide-sensitive 7 dpf larvae, we identified several such compounds that offer significant protection against cyanide toxicity. Modulators of the pyruvate dehydrogenase complex, as well as the small molecule sodium glyoxylate, consistently protected against cyanide toxicity in 7 dpf zebrafish larvae. Together, our results indicate that the resistance of zebrafish embryos to cyanide toxicity during early development is related to an altered regulation of cellular metabolism, which we propose may be exploited as a potential target for the development of novel antidotes against cyanide poisoning.
Topics: Animals; Metabolome; Metabolomics; Potassium Cyanide; Pyruvate Dehydrogenase Complex; Swine; Zebrafish; Zebrafish Proteins
PubMed: 29879736
DOI: 10.1371/journal.pone.0193889