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1.
Chem Res Toxicol ; 34(6): 1530-1541, 2021 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-33914522

RESUMO

Smoke inhalation from a structure fire is a common route of cyanide poisoning in the U.S. Cyanide inhibits cellular respiration, often leading to death. Its rapid distribution throughout the body can result in injuries to multiple organs, and cyanide victims were reported to experience myocardial infarction and other cardiac complications. However, molecular mechanisms of such complications are yet to be elucidated. While FDA-approved CN antidotes such as sodium thiosulfate and hydroxocobalamin are clinically used, they have foreseeable limitations during mass casualty situations because they require intravenous administration. To facilitate the development of better antidotes and therapeutic treatments, a global view of molecular changes induced by cyanide exposure is necessary. As an exploratory pursuit, we performed oligonucleotide microarrays to establish cardiac transcriptomes of an animal model of nose-only inhalation exposure to hydrogen cyanide (HCN), which is relevant to smoke inhalation. We also profiled cardiac transcriptomes after subcutaneous injection of potassium cyanide (KCN). Although the KCN injection model has often been used to evaluate medical countermeasures, this study demonstrated that cardiac transcriptomes are largely different from that of the HCN inhalation model at multiple time points within 24 h after exposure. Pathway analysis identified that HCN-induced transcriptomes were enriched with genes encoding mediators of pathways critical in modulation of cardiac complications and that a large number of such genes were significantly decreased in expression. We utilized the upstream regulatory analysis to propose drugs that can be potentially employed to treat cyanide-induced cardiac complications.


Assuntos
Traumatismos Cardíacos/complicações , Cianeto de Hidrogênio/envenenamento , Cianeto de Potássio/envenenamento , Animais , Cianeto de Hidrogênio/administração & dosagem , Exposição por Inalação , Injeções Subcutâneas , Masculino , Camundongos , Cianeto de Potássio/administração & dosagem
2.
Clin Biochem ; 91: 31-38, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33444605

RESUMO

OBJECTIVES: Hydroxocobalamin (OHCob) is an antidote for cyanide poisoning in patients rescued from house fires and is known to cause interference with certain laboratory tests. Consensus is lacking on the extent of this interference and on how to handle these samples. The objectives of this study were to characterize OHCob interference across a wide range of laboratory tests and to develop protocols for identifying and reporting these samples. DESIGNS & METHODS: Patient plasma samples (n = 5) were spiked with OHCob (1.5 mg/mL) and compared to controls without this drug. A series of analytes were measured using chemistry, urinalysis, coagulation, hematology, and blood gas instruments. Dose-response testing was performed on a subset of assays that showed interferences ≥10%. RESULTS: Of the 77 analytes evaluated, 27 (35%) showed interference from OHCob, with chemistry and coagulation analytes showing the greatest effects. Of those affected, 22 analytes had a positive interference, whereas 5 analytes had negative interference. Dose-response studies showed dose-dependent increases and/or decreases consistent with initial spiking studies. Although red in colour, plasma samples with OHCob did not trigger hemolysis index flags, necessitating a special sample identification and reporting protocol. CONCLUSION: OHCob had significant effects on several analytes across different instruments. These findings led to the development of special sample handling and reporting protocols to identify OHCob samples and ensure only accurate results are released. It is vital for emergency departments to document and notify their laboratories whenever blood samples from these patients are drawn.


Assuntos
Antídotos/farmacocinética , Análise Química do Sangue , Hidroxocobalamina/farmacocinética , Envenenamento , Cianeto de Potássio , Antídotos/administração & dosagem , Feminino , Humanos , Hidroxocobalamina/administração & dosagem , Masculino , Envenenamento/sangue , Envenenamento/tratamento farmacológico
3.
Clin Toxicol (Phila) ; 59(8): 734-739, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33274646

RESUMO

OBJECTIVE: In this proof-of-concept study, the aim was to evaluate the short-term clinical effectiveness of isosorbide dinitrate (ISDN) oral spray in non-anaesthetized cyanide-poisoned swine. METHODS: A comparative study was conducted using domestic swine. Animals were intravenously poisoned with potassium cyanide (KCN), either 2 mg/kg or 4 mg/kg dose. Two control groups (one for each cyanide dose) were not further treated. Two other groups (one for each cyanide dose) were treated within 1 min after poisoning with ISDN oral spray: 3 spray actuations (averaging a total of 3.75 mg) after the lower cyanide dose and 4 spray actuations (averaging a total of 5.0 mg) after the higher dose. The study outcomes were clinical score, time to death, and blood tests including pH, lactate, and methemoglobin levels. RESULTS: All the animals started to convulse within 20 to 30 sec after KCN poisoning, then became unresponsive and hemodynamically depressed after another 20 to 30 sec. After the KCN 2 mg/kg dose, 3 of 4 control animals survived, while all treated animals survived. Compared with control animals, ISDN-treated animals displayed significantly better clinical scores starting 5 min after KCN poisoning. Acidosis was significantly more pronounced in the untreated animals. After the KCN 4 mg/kg dose, similar survival rates were observed for control and ISDN-treated groups (1/4), but treated animals had longer time to death and better pH and lactate levels. CONCLUSION: ISDN oral spray administration following KCN poisoning in this porcine model did not result in statistically significant increased survival. However, based on clinical scores and clinical laboratory values, ISDN may benefit as a bridging countermeasure until currently-available specific cyanide antidotes can be administered. Further research is warranted to better characterize this potential role of ISDN in cyanide poisoning.


Assuntos
Antídotos/administração & dosagem , Cianetos/envenenamento , Dinitrato de Isossorbida/administração & dosagem , Animais , Antídotos/farmacologia , Estudos de Casos e Controles , Relação Dose-Resposta a Droga , Dinitrato de Isossorbida/farmacologia , Ácido Láctico/sangue , Masculino , Metemoglobina/análise , Sprays Orais , Cianeto de Potássio/administração & dosagem , Cianeto de Potássio/envenenamento , Estudo de Prova de Conceito , Taxa de Sobrevida , Suínos
4.
Am J Physiol Regul Integr Comp Physiol ; 320(3): R203-R212, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33206558

RESUMO

Activation of the carotid body (CB) using intracarotid potassium cyanide (KCN) injection increases coronary blood flow (CoBF). This increase in CoBF is considered to be mediated by co-activation of both the sympathetic and parasympathetic nerves to the heart. However, whether cardiac sympathetic nerve activity (cardiac SNA) actually increases during CB activation has not been determined previously. We hypothesized that activation of the CB would increase directly recorded cardiac SNA, which would cause coronary vasodilatation. Experiments were conducted in conscious sheep implanted with electrodes to record cardiac SNA and diaphragmatic electromyography (dEMG), flow probes to record CoBF and cardiac output, and a catheter to record arterial pressure. Intracarotid KCN injection was used to activate the CB. To eliminate the contribution of metabolic demand on coronary flow, the heart was paced at a constant rate during CB chemoreflex stimulation. Intracarotid KCN injection resulted in a significant increase in directly recorded cardiac SNA frequency (from 24 ± 2 to 40 ± 4 bursts/min; P < 0.05) as well as a dose-dependent increase in mean arterial pressure (79 ± 15 to 88 ± 14 mmHg; P < 0.01) and CoBF (75 ± 37 vs. 86 ± 42 mL/min; P < 0.05). The increase in CoBF and coronary vascular conductance to intracarotid KCN injection was abolished after propranolol infusion, suggesting that the increased cardiac SNA mediates coronary vasodilatation. The pressor response to activation of the CB was abolished by pretreatment with intravenous atropine, but there was no change in the coronary flow response. Our results indicate that CB activation increases directly recorded cardiac SNA, which mediates vasodilatation of the coronary vasculature.


Assuntos
Corpo Carotídeo/efeitos dos fármacos , Circulação Coronária/efeitos dos fármacos , Coração/inervação , Cianeto de Potássio/farmacologia , Sistema Nervoso Simpático/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Animais , Pressão Arterial/efeitos dos fármacos , Corpo Carotídeo/metabolismo , Estado de Consciência , Feminino , Carneiro Doméstico , Sistema Nervoso Simpático/fisiologia , Fatores de Tempo
5.
Neurochem Res ; 46(1): 100-107, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32130629

RESUMO

Reductions in the activities of mitochondrial electron transport chain (ETC) enzymes have been implicated in the pathogenesis of numerous chronic neurodegenerative disorders. Maintenance of the mitochondrial membrane potential (Δψm) is a primary function of these enzyme complexes, and is essential for ATP production and neuronal survival. We examined the effects of inhibition of mitochondrial ETC complexes I, II/III, III and IV activities by titrations of respective inhibitors on Δψm in synaptosomal mitochondria. Small perturbations in the activity of complex I, brought about by low concentrations of rotenone (1-50 nM), caused depolarisation of Δψm. Small decreases in complex I activity caused an immediate and partial Δψm depolarisation, whereas inhibition of complex II/III activity by more than 70% with antimycin A was required to affect Δψm. A similarly high threshold of inhibition was found when complex III was inhibited with myxothiazol, and inhibition of complex IV by more than 90% with KCN was required. The plasma membrane potential (Δψp) had a complex I inhibition threshold of 40% whereas complex III and IV had to be inhibited by more than 90% before changes in Δψp were registered. These data indicate that in synaptosomes, both Δψm and Δψp are more susceptible to reductions in complex I activity than reductions in the other ETC complexes. These findings may be of relevance to the mechanism of neuronal cell death in Parkinson's disease in particular, where such reductions in complex I activity are present.


Assuntos
Complexo I de Transporte de Elétrons/metabolismo , Potencial da Membrana Mitocondrial/fisiologia , Mitocôndrias/metabolismo , Animais , Antimicina A/farmacologia , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Ensaios Enzimáticos , Inibidores Enzimáticos/farmacologia , Feminino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Metacrilatos/farmacologia , Mitocôndrias/efeitos dos fármacos , Cianeto de Potássio/farmacologia , Ratos Wistar , Rotenona/farmacologia , Sinaptossomos/efeitos dos fármacos , Tiazóis/farmacologia
6.
Am J Physiol Regul Integr Comp Physiol ; 319(1): R96-R105, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32459971

RESUMO

The rectal gland of the spiny dogfish Squalus acanthias secretes a salt solution isosmotic with plasma that maintains the salt homeostasis of the fish. It secretes salt against an electrochemical gradient that requires the expenditure of energy. Isolated rectal glands perfused without glucose secrete salt, albeit at a rate about 30% of glands perfused with 5 mM glucose. Gradually reducing the glucose concentration is associated with a progressive decrease in the secretion of chloride. The apparent Km for the exogenous glucose-dependent chloride secretion is around 2 mM. Phloretin and cytochalasin B, agents that inhibit facilitated glucose carriers of the solute carrier 2 (Slc2) family such as glucose transporter 2 (GLUT2), do not inhibit the secretion of chloride by the perfused rectal glands. Phloridzin, which inhibits Slc5 family of glucose symporters, or α-methyl-d-glucoside, which competitively inhibits the uptake of glucose through Slc5 symporters, inhibit the secretion of chloride. Thus the movement of glucose into the rectal gland cells appears to be mediated by a sodium-glucose symporter. Sodium-glucose cotransporter 1 (SGLT1), the first member of the Slc5 family of sodium-linked glucose symporters, was cloned from the rectal gland. No evidence of GLUT2 was found. The persistence of secretion of chloride in the absence of glucose in the perfusate suggests that there is an additional source of energy within the cells. The use of 2-mercapto-acetate did not result in any change in the secretion of chloride, suggesting that the oxidation of fatty acids is not the source of energy for the secretion of chloride. Perfusion of isolated glands with KCN in the absence of glucose further reduces the secretion of chloride but does not abolish it, again suggesting that there is another source of energy within the cells. Glucose was measured in the rectal gland cells and found to be at concentrations in the range of that in the perfusate. Glycogen measurements indicated that there are significant stores of glucose in the rectal gland. Moreover, glycogen synthase was partially cloned from rectal gland cells. The open reading frame of glycogen phosphorylase was also cloned from rectal gland cells. Measurements of glycogen phosphorylase showed that the enzyme is mostly in its active form in the cells. The cells of the rectal gland of the spiny dogfish require exogenous glucose to fully support the active secretion of salt. They have the means to transport glucose into the cells in the form of SGLT1. The cells also have an endogenous supply of glucose as glycogen and have the necessary elements to synthesize, store, and hydrolyze it.


Assuntos
Cloretos/metabolismo , Glucose/metabolismo , Glândula de Sal/metabolismo , Squalus/metabolismo , Animais , Sequência de Bases , Glucose/farmacologia , Transportador de Glucose Tipo 2/metabolismo , Glicogênio/metabolismo , Glicogênio Fosforilase/metabolismo , Glicogênio Sintase/metabolismo , Homeostase , Técnicas In Vitro , Cianeto de Potássio/farmacologia , Glândula de Sal/efeitos dos fármacos , Transportador 1 de Glucose-Sódio/metabolismo , Proteínas Cotransportadoras de Sódio-Fosfato Tipo II/metabolismo
7.
Ann N Y Acad Sci ; 1479(1): 108-121, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32374444

RESUMO

The aim of the present study was to determine whether methylene blue (MB) could directly oppose the neurological toxicity of a lethal cyanide (CN) intoxication. KCN, infused at the rate of 0.375 mg/kg/min intravenously, produced 100% lethality within 15 min in unanaesthetized rats (n = 12). MB at 10 (n = 5) or 20 mg/kg (n = 5), administered 3 min into CN infusion, allowed all animals to survive with no sequelae. No apnea and gasping were observed at 20 mg/kg MB (P < 0.001). The onset of coma was also significantly delayed and recovery from coma was shortened in a dose-dependent manner (median of 359 and 737 seconds, respectively, at 20 and 10 mg/kg). At 4 mg/kg MB (n = 5), all animals presented faster onset of coma and apnea and a longer period of recovery than at the highest doses (median 1344 seconds, P < 0.001). MB reversed NaCN-induced resting membrane potential depolarization and action potential depression in primary cultures of human fetal neurons intoxicated with CN. MB restored calcium homeostasis in the CN-intoxicated human SH-SY5Y neuroblastoma cell line. We conclude that MB mitigates the neuronal toxicity of CN in a dose-dependent manner, preventing the lethal depression of respiratory medullary neurons and fatal outcome.


Assuntos
Antídotos/farmacologia , Azul de Metileno/farmacologia , Neurônios , Síndromes Neurotóxicas , Cianeto de Potássio/toxicidade , Animais , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Humanos , Masculino , Neurônios/metabolismo , Neurônios/patologia , Síndromes Neurotóxicas/metabolismo , Síndromes Neurotóxicas/patologia , Síndromes Neurotóxicas/prevenção & controle , Ratos , Ratos Sprague-Dawley
8.
Colloids Surf B Biointerfaces ; 187: 110650, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31787457

RESUMO

DNA functionalized gold nanoparticles (DNA-AuNPs) have shown great potential for biosensing as they combine the excellent optical properties of gold nanoparticles and the molecular recognition function of DNA. Since the DNA density determines the assay performance and the stability of the conjugate, a precise control of the surface density of DNA-AuNP is crucial for an optimized biosensor. Here we report a simple assay for quantifying multiple unlabeled DNAs on AuNPs. The assay relies on potassium cyanide (KCN) to first dissolve the AuNPs, which then releases surface bound DNA for quantification through a double-stranded DNA dye. Using this analytical quantification method, we investigated several strategies to control the surface density of DNA-AuNPs. Besides the precise control of DNA density, the stability of DNA-AuNPs after conjugation is also important in developing a biosensor with optimal performance. Without proper storing conditions, DNA-AuNPs are unstable and aggregate over time. To overcome this problem, we developed a long-term storage solution to ensure the stability and quality of DNA-AuNPs after conjugation which would benefit any DNA-AuNP-based biosensor.


Assuntos
Técnicas Biossensoriais/métodos , DNA/análise , DNA/química , Ouro/química , Nanopartículas Metálicas/química , Coloides/química , Ditiotreitol/química , Congelamento , Ligantes , MicroRNAs/química , MicroRNAs/metabolismo , Cianeto de Potássio/química , Compostos de Sulfidrila/química
9.
BMC Genomics ; 20(1): 942, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31810444

RESUMO

BACKGROUND: Mycobacterium smegmatis is a saprophytic bacterium frequently used as a genetic surrogate to study pathogenic Mycobacterium tuberculosis. The PrrAB two-component genetic regulatory system is essential in M. tuberculosis and represents an attractive therapeutic target. In this study, transcriptomic analysis (RNA-seq) of an M. smegmatis ΔprrAB mutant was used to define the PrrAB regulon and provide insights into the essential nature of PrrAB in M. tuberculosis. RESULTS: RNA-seq differential expression analysis of M. smegmatis wild-type (WT), ΔprrAB mutant, and complementation strains revealed that during in vitro exponential growth, PrrAB regulates 167 genes (q < 0.05), 57% of which are induced in the WT background. Gene ontology and cluster of orthologous groups analyses showed that PrrAB regulates genes participating in ion homeostasis, redox balance, metabolism, and energy production. PrrAB induced transcription of dosR (devR), a response regulator gene that promotes latent infection in M. tuberculosis and 21 of the 25 M. smegmatis DosRS regulon homologues. Compared to the WT and complementation strains, the ΔprrAB mutant exhibited an exaggerated delayed growth phenotype upon exposure to potassium cyanide and respiratory inhibition. Gene expression profiling correlated with these growth deficiency results, revealing that PrrAB induces transcription of the high-affinity cytochrome bd oxidase genes under both aerobic and hypoxic conditions. ATP synthesis was ~ 64% lower in the ΔprrAB mutant relative to the WT strain, further demonstrating that PrrAB regulates energy production. CONCLUSIONS: The M. smegmatis PrrAB two-component system regulates respiratory and oxidative phosphorylation pathways, potentially to provide tolerance against the dynamic environmental conditions experienced in its natural ecological niche. PrrAB positively regulates ATP levels during exponential growth, presumably through transcriptional activation of both terminal respiratory branches (cytochrome c bc1-aa3 and cytochrome bd oxidases), despite transcriptional repression of ATP synthase genes. Additionally, PrrAB positively regulates expression of the dormancy-associated dosR response regulator genes in an oxygen-independent manner, which may serve to fine-tune sensory perception of environmental stimuli associated with metabolic repression.


Assuntos
Perfilação da Expressão Gênica/métodos , Redes Reguladoras de Genes , Mutação , Mycobacterium smegmatis/fisiologia , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Teste de Complementação Genética , Mycobacterium smegmatis/efeitos dos fármacos , Mycobacterium smegmatis/genética , Cianeto de Potássio/farmacologia , Regulon , Análise de Sequência de RNA/métodos
11.
BMJ Case Rep ; 12(7)2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31350229

RESUMO

While potassium cyanide poisoning has been well described, the toxicity of potassium gold cyanide is less well understood. This case describes an 84-year-old man who presented after an intentional ingestion of 0.5-1 teaspoons of potassium gold cyanide. Despite antidotal therapy, the patient rapidly developed severe lactic acidosis, multiorgan dysfunction and ultimately expired. While the patient's clinical findings were consistent with acute cyanide poisoning, a serum cyanide level was below the toxic threshold. Previous reports have suggested that gold toxicity may also contribute to the effects of potassium gold cyanide, and may have played a role in the patient's rapid decline. In addition to treatment of cyanide toxicity, management of acute gold toxicity should also be considered in potassium gold cyanide ingestion.


Assuntos
Acidose Láctica/induzido quimicamente , Cianatos/envenenamento , Compostos de Ouro/envenenamento , Ouro/envenenamento , Cianeto de Potássio/envenenamento , Suicídio , Idoso de 80 Anos ou mais , Humanos , Masculino
12.
Ann Emerg Med ; 74(3): 423-429, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31080026

RESUMO

STUDY OBJECTIVE: Cyanide is a deadly poison, particularly with oral exposure, in which larger doses can occur before any symptoms develop. Multiple governmental agencies highlight oral cyanide as an agent that can be used in a terrorist attack because it can be easily weaponized and is readily available. Currently, there are no Food and Drug Administration-approved antidotes specifically for oral cyanide. An oral countermeasure that can neutralize and prevent absorption of cyanide from the gastrointestinal tract after oral exposure is needed. The objective of this study is to determine if the combination of glycine and sodium thiosulfate administered orally is effective in reducing mortality in a large, swine model of oral cyanide toxicity. METHODS: Nine swine (45 to 55 kg) were instrumented, sedated, and stabilized. Potassium cyanide (at 8 mg/kg) in saline solution was delivered as a onetime bolus through an orogastric tube. Three minutes after cyanide administration, animals that were randomized to the treatment group received sodium thiosulfate (508.2 mg/kg, 3.25-M solution) and glycine (30 mg/kg, 3.5-M solution) through an orogastric tube. Survival at 60 minutes was the primary outcome. We compared survival between groups by log-rank Mantel-Cox analysis and trended laboratory results and vital signs. RESULTS: At baseline and treatment, all animals were similar. Survival at 60 minutes was 100% in treated animals compared with 0% in the control group (P=.003). By the study end, defined as death or 60 minutes after cyanide administration, there was a significant difference in the lactate concentration between the treatment and control groups (control 9.43 mmol/L [SD 4.08]; treatment 1.66 mmol/L [SD 0.82]; difference between means 7.69 mmol/L [SD 2.07]; 95% confidence interval difference -14.05 to -1.32). Mean arterial pressure was significantly different between the treatment and control groups at study end (control 26 mm Hg [SD 6.7]; treatment 81 mm Hg [SD 14]; difference between means 55.2 mm Hg [SD 7.1]; 95% confidence interval difference 37.8 to 72.6). pH and oxygen saturation were also significantly different between the treatment and control groups at study end. CONCLUSION: The combination of oral sodium thiosulfate and glycine significantly improved survival and physiologic parameters in a large-animal model of oral cyanide toxicity.


Assuntos
Antídotos/administração & dosagem , Glicina/administração & dosagem , Cianeto de Potássio/envenenamento , Tiossulfatos/administração & dosagem , Administração Oral , Animais , Antídotos/farmacocinética , Modelos Animais de Doenças , Quimioterapia Combinada , Feminino , Glicina/farmacologia , Humanos , Venenos , Distribuição Aleatória , Suínos , Tiossulfatos/farmacologia , Fatores de Tempo
13.
J Pharm Biomed Anal ; 171: 132-147, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30999224

RESUMO

Belizatinib (BZB; TSR-011) is a next-generation anaplastic lymphoma kinase inhibitor that also inhibits tropomyosin-related kinases A/B/C. In this in-vitro study, we examined the formation of reactive metabolites from BZB using rat liver microsomes or human liver microsomes in the presence of a trapping agent (potassium cyanide) to generate iminium reactive intermediates. Identification of the in vitro BZB metabolites indicated that the major in-vitro metabolic reaction involved hydroxylation of the piperidine moiety. We identified eight in-vitro phase I metabolites and three iminium reactive intermediates, suggesting two possible BZB-bioactivation pathways. We propose that the tertiary nitrogen in the piperidine ring activates the attached benzyl carbon in addition to the two α carbons inside the ring. To our knowledge, this is the first report on the structural identification of reactive metabolites derived from BZB.


Assuntos
Quinase do Linfoma Anaplásico/antagonistas & inibidores , Antineoplásicos/metabolismo , Benzamidas/metabolismo , Microssomos Hepáticos/metabolismo , Inibidores de Proteínas Quinases/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Humanos , Técnicas In Vitro , Estrutura Molecular , Cianeto de Potássio/química , Ratos
14.
J Toxicol Sci ; 44(3): 201-211, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30842372

RESUMO

This study was aimed to predict drug-induced liver injury caused by reactive metabolites. Reactive metabolites covalently bind to proteins and could result in severe outcomes in patients. However, the relation between the extent of covalent binding and clinical hepatotoxicity is still unclear. From a perspective of body burden (human in vivo exposure to reactive metabolites), we developed a risk assessment method in which reactive metabolite burden (RM burden), an index that could reflect the body burden associated with reactive metabolite exposure, is calculated using the extent of covalent binding, clinical dose, and human in vivo clearance. The relationship between RM burden and hepatotoxicity in humans was then investigated. The results indicated that this RM burden assessment exhibited good predictability for sensitivity and specificity, and drugs with over 10 mg/day RM burden have high-risk for hepatotoxicity. Furthermore, a quantitative trapping assay using radiolabeled trapping agents ([35S]cysteine and [14C]KCN) was also developed, to detect reactive metabolite formation in the early drug discovery stage. RM burden calculated using this assay showed as good predictability as RM burden calculated using conventional time- and cost-consuming covalent binding assays. These results indicated that the combination of RM burden and our trapping assay would be a good risk assessment method for reactive metabolites from the drug discovery stage.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Medição de Risco/métodos , Carga Corporal (Radioterapia) , Cisteína/metabolismo , Descoberta de Drogas , Humanos , Microssomos Hepáticos/metabolismo , Preparações Farmacêuticas/metabolismo , Cianeto de Potássio/metabolismo
15.
Toxicol Mech Methods ; 29(6): 438-444, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30822191

RESUMO

Formulation optimization and antidotal combination therapy are the two important tools to enhance the antidotal protection of the cyanide (CN) antidote dimethyl trisulfide (DMTS). The focus of this study is to demonstrate how the formulation with polysorbate 80 (Poly80), an excipient used in pharmaceutical technology, and the combinations with other CN antidotes having different mechanisms of action enhance the antidotal efficacy of the unformulated (neat) DMTS. The LD50 for CN was determined by the statistical Dixon up-and-down method on mice. Antidotal efficacy was expressed as antidotal potency ratio (APR). CN was injected subcutaneously one minute prior to the antidotes' injection intramuscularly. The APR values of 1.17 (dose: 25 mg/kg bodyweight) and 1.45 (dose: 50 mg/kg bodyweight) of the neat DMTS were significantly enhanced by the Poly80 formulation at both investigated doses to 2.03 and 2.33, respectively. The combination partners for the Poly80 formulated DMTS (DMTS-Poly80; 25 and 50 mg/kg bodyweight) were 4-nitrocobinamide (4NCbi) (20 mg/kg bodyweight) and aquohydroxocobinamide (AHCbi; 50, 100, and 250 mg/kg bodyweight). When DMTS-Poly80 (25 and 50 mg/kg bodyweight; APR = 2.03 and 2.33, respectively) was combined with 4NCbi (20 mg/kg bodyweight; APR = 1.35), significant increase in the APR values were noted at both DMTS doses (APR = 2.38 and 3.12, respectively). AHCbi enhanced the APR of DMTS-Poly80 (100 mg/kg bodyweight; APR = 3.29) significantly only at the dose of 250 mg/kg bodyweight (APR = 5.86). These studies provided evidence for the importance of the formulation with Poly80 and the combinations with cobinamide derivatives with different mechanisms of action for DMTS as a CN antidote candidate.


Assuntos
Antídotos/uso terapêutico , Cobamidas/uso terapêutico , Cianeto de Potássio/envenenamento , Sulfetos/uso terapêutico , Animais , Antídotos/administração & dosagem , Antídotos/química , Cobamidas/administração & dosagem , Cobamidas/química , Relação Dose-Resposta a Droga , Composição de Medicamentos , Quimioterapia Combinada , Excipientes , Dose Letal Mediana , Masculino , Camundongos Endogâmicos , Polissorbatos , Sulfetos/administração & dosagem , Sulfetos/química
16.
Auton Neurosci ; 216: 17-24, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30598121

RESUMO

Electrical stimulation of the carotid baroreflex has been thoroughly investigated for treating drug-resistant hypertension in humans. However, a previous study from our laboratory, performed in conscious rats, has demonstrated that electrical stimulation of the carotid sinus/nerve (CS) activated both the carotid baroreflex as well as the carotid chemoreflex, resulting in hypotension. Additionally, we also demonstrated that the carotid chemoreceptor deactivation potentiated this hypotensive response. Therefore, to further investigate this carotid baroreflex/chemoreflex interaction, besides the hemodynamic responses, we evaluated the respiratory responses to the electrical stimulation of the CS in both intact (CONT) and carotid chemoreceptors deactivated (CHEMO-X) conscious rats. CONT rats showed increased ventilation in response to electrical stimulation of the CS as measured by the respiratory frequency (fR), tidal volume (VT) and minute ventilation (VE), suggesting a carotid chemoreflex activation. The carotid chemoreceptor deactivation abolished all respiratory responses to the electrical stimulation of the CS. Regarding the hemodynamic responses, the electrical stimulation of the CS caused hypotensive responses in CONT rats, which were potentiated by the carotid chemoreceptors deactivation. Heart rate (HR) responses did not differ between groups. In conclusion, the present study showed that the electrical stimulation of the CS, in conscious rats, activates both the carotid baroreflex and the carotid chemoreflex driving an increase in ventilation and a decrease in AP. These findings further contribute to our understanding of the electrical stimulation of CS.


Assuntos
Barorreflexo/fisiologia , Seio Carotídeo/fisiologia , Células Quimiorreceptoras/fisiologia , Hemodinâmica/fisiologia , Respiração , Animais , Barorreflexo/efeitos dos fármacos , Células Quimiorreceptoras/efeitos dos fármacos , Estado de Consciência , Estimulação Elétrica , Hipotensão/fisiopatologia , Masculino , Cianeto de Potássio/farmacologia , Ratos
17.
Drug Chem Toxicol ; 42(6): 577-584, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29609494

RESUMO

Cyanide-induced chemical hypoxia is responsible for pronounced oxidative damage in the central nervous system. The disruption of mitochondrial oxidative metabolism has been associated with upregulation of uncoupling proteins (UCPs). The present study addresses the dose- and time-dependent effect of sub-acute cyanide exposure on various non-enzymatic and enzymatic oxidative stress markers and their correlation with inducible-nitric oxide synthase (iNOS) and uncoupling protein-2 (UCP-2) expression. Animals received (oral) triple distilled water (vehicle control), 0.25 LD50 potassium cyanide (KCN) or 0.50 LD50 KCN daily for 21 d. Animals were sacrificed on 7, 14 and 21 d post-exposure to measure serum cyanide and nitrite, and brain malondialdehyde (MDA), reduced glutathione (GSH), glutathione disulfide (GSSG), cytochrome c oxidase (CCO), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CA) levels, together with iNOS and UCP-2 expression, and DNA damage. The study revealed that a dose- and time-dependent increase in cyanide concentration was accompanied by corresponding CCO inhibition and elevated MDA levels. Decrease in GSH levels was not followed by reciprocal change in GSSG levels. Diminution of SOD, GPx, GR and CA activity was congruent with elevated nitrite levels and upregulation of iNOS and UCP-2 expression, without any DNA damage. It was concluded that long-term cyanide exposure caused oxidative stress, accompanied by upregulation of iNOS. The upregulation of UCP-2 further sensitized the cells to cyanide and accentuated the oxidative stress, which was independent of DNA damage.


Assuntos
Óxido Nítrico Sintase Tipo II/genética , Estresse Oxidativo/efeitos dos fármacos , Cianeto de Potássio/toxicidade , Proteína Desacopladora 2/genética , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Dano ao DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Dose Letal Mediana , Cianeto de Potássio/administração & dosagem , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo , Fatores de Tempo , Regulação para Cima/efeitos dos fármacos
18.
Clin Toxicol (Phila) ; 57(4): 265-270, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30306816

RESUMO

BACKGROUND: Cyanide is a deadly compound used as a terrorist agent. Current FDA approved antidotes require intravenous administration, limiting their utility in a mass casualty scenario. Dimethyl trisulfide (DMTS), a sulfur-based molecule, binds cyanide converting it to the less toxic by-product thiocyanate. Studies evaluating efficacy in rodents have been performed, but a large, clinically relevant animal model has not been reported. OBJECTIVE: This study evaluates the efficacy of intramuscular DMTS on survival and clinical outcomes in a swine model of acute, severe cyanide toxicity. METHODS: Anesthetized swine were instrumented for continuous monitoring of hemodynamics. Prior to potassium cyanide infusion animals were acclimated and breathing spontaneously. At 5-minutes post-apnea animals were treated with DMTS or saline. Vital signs, hemodynamics, and laboratory values were evaluated at various time points. RESULTS: Baseline values and time to apnea were similar in both groups. Survival in the DMTS treated group was 83.3% and 0% in saline controls (p = .005). The DMTS group returned to breathing at a mean time of 19.3 ± 10 min after antidote, control animals did not return to breathing (CI difference 8.8, 29.8). At the end of the experiment or time of death, mean lactate was 9.41 mmol/L vs. 4.35 mmol/L (CI difference -10.94,0.82) in the saline and DMTS groups, respectively and pH was 7.20 vs. 7.37 (CI difference -0.04, 0.38). No adverse effects were observed at the injection site. CONCLUSION: Intramuscular administration of DMTS improves survival and clinical outcomes in our large animal swine model of acute cyanide toxicity.


Assuntos
Antídotos/administração & dosagem , Cianeto de Potássio/envenenamento , Sulfetos/administração & dosagem , Animais , Antídotos/farmacologia , Modelos Animais de Doenças , Feminino , Injeções Intramusculares , Cianeto de Potássio/toxicidade , Sulfetos/farmacologia , Suínos , Testes de Toxicidade Aguda , Resultado do Tratamento
19.
Free Radic Res ; 52(9): 1052-1062, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30175632

RESUMO

The objectives of this study were to develop a robust protocol to measure the rate of hydrogen peroxide (H2O2) production in isolated perfused rat lungs, as an index of oxidative stress, and to determine the cellular sources of the measured H2O2 using the extracellular probe Amplex red (AR). AR was added to the recirculating perfusate in an isolated perfused rat lung. AR's highly fluorescent oxidation product resorufin was measured in the perfusate. Experiments were carried out without and with rotenone (complex I inhibitor), thenoyltrifluoroacetone (complex II inhibitor), antimycin A (complex III inhibitor), potassium cyanide (complex IV inhibitor), or diohenylene iodonium (inhibitor of flavin-containing enzymes, e.g. NAD(P)H oxidase or NOX) added to the perfusate. We also evaluated the effect of acute changes in oxygen (O2) concentration of ventilation gas on lung rate of H2O2 release into the perfusate. Baseline lung rate of H2O2 release was 8.45 ± 0.31 (SEM) nmol/min/g dry wt. Inhibiting mitochondrial complex II reduced this rate by 76%, and inhibiting flavin-containing enzymes reduced it by another 23%. Inhibiting complex I had a small (13%) effect on the rate, whereas inhibiting complex III had no effect. Inhibiting complex IV increased this rate by 310%. Increasing %O2 in the ventilation gas mixture from 15 to 95% had a small (27%) effect on this rate, and this O2-dependent increase was mostly nonmitochondrial. Results suggest complex II as a potentially important source and/or regulator of mitochondrial H2O2, and that most of acute hyperoxia-enhanced lung rate of H2O2 release is from nonmitochondrial rather than mitochondrial sources.


Assuntos
Complexo de Proteínas da Cadeia de Transporte de Elétrons/antagonistas & inibidores , Peróxido de Hidrogênio/isolamento & purificação , Pulmão/química , Estresse Oxidativo/efeitos dos fármacos , Animais , Antimicina A/farmacologia , Complexo de Proteínas da Cadeia de Transporte de Elétrons/química , Peróxido de Hidrogênio/química , Pulmão/efeitos dos fármacos , Mitocôndrias/química , Mitocôndrias/efeitos dos fármacos , Técnicas de Cultura de Órgãos , Oxazinas/química , Oxazinas/farmacologia , Oxirredução/efeitos dos fármacos , Cianeto de Potássio/farmacologia , Ratos , Espécies Reativas de Oxigênio/química , Rotenona/farmacologia , Tenoiltrifluoracetona/farmacologia
20.
Comp Med ; 68(5): 375-379, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30208987

RESUMO

Cyanide is a readily available and potentially lethal substance. Oral exposure can result in larger doses, compared with other routes. Currently, there are no antidotes specific for use in the treatment of oral cyanide poisoning, and studies cannot be done in humans. We report on a new large animal model of oral cyanide toxicity to evaluate potential antidotes. Six female swine (Sus scrofa; weight, 45 to 55 kg) were anesthetized, intubated, and instrumented. Animals received a KCN bolus of either 5 or 8 mg/kg delivered via orogastric tube. Time to apnea was recorded; parameters monitored included heart rate, respiratory rate, blood pressure, pulse oximetry, end-tidal CO2, arterial blood gasses, and lactate concentrations. The Welch t test was used to calculate confidence intervals, mean, and standard deviation, and a Kaplan-Meier survival curve was used to compare survival between the 2 groups. At baseline, all animals in both groups were similar. Animals in the 5-mg/kg group had a more rapid time to apnea (5.1 ± 2.1 min), longer time to death (48.5 ± 38.1 min), and a greater rate of survival than the 8-mg/kg group (apnea, 10.6 ± 10.7 min; death, 26.1 ± 5.8 min). All animals displayed signs of toxicity (acidemia, hyperlactatemia, hypotension, apnea). We here report a large animal (swine) model of oral cyanide poisoning with dose-dependent effects in regard to time to death and survival rate. This model likely will be valuable for the development of medical countermeasures for oral cyanide poisoning.


Assuntos
Modelos Animais de Doenças , Cianeto de Potássio/toxicidade , Suínos , Administração Oral , Animais , Feminino , Estimativa de Kaplan-Meier , Monitorização Fisiológica/veterinária , Cianeto de Potássio/administração & dosagem , Cianeto de Potássio/envenenamento
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