[Cyanide, in And Then There Were None, Sparkling Cyanide].

And Then There Were None and Sparkling Cyanide, two of Agatha Christie's famous novels describe potassium cyanide-induced deaths. Cyanide, a tasteless, odorless, strongly alkaline poison is a powerful gastrointestinal irritant, following oral ingestion. It reacts with hydrochloric acid in the gastric juice to produce hydrogen cyanide gas, which is absorbed and inhibits the mitochondrial electron transfer system and consequently suppresses adenosine triphosphate (ATP) production. Therefore, the central nervous system, which consumes a large amount of ATP, is first affected and symptoms of poisoning manifest as dizziness, disorientation, coma, and convulsions. The orally lethal dose is approximately 300 mg.

Studies on the enzymatic specificity of diguanylate cyclases domains and the production of new second messengers / Estudos na especificidade enzimática de diguanilato ciclases e na produção de novos segundos mensageiros

In the first chapter, studies on substrate recognition and enzymatic activity of GGDEF domains are presented. Many proteins containing GGDEF domains are diguanylate cyclases (DGCs, EC 2.7.7.65), enzymes that catalyze the conversion of 2 GTP molecules into the second messenger c-di-GMP in prokaryotes. This molecule is primarily implicated in the transition between motile and sessile lifestyles, as well several other phenotypes. Redundancy and diversity of GGDEF domain sequences in many bacterial genomes raises the possibility that other enzymatic functions may yet be discovered. To test this hypothesis, i) the effect of point mutations on the structure and enzymatic activity of GGDEF domains is analyzed, ii) the enzymatic specificity of wild-type GGDEF domains from different proteins is also tested, and iii) when non-canonical products are detected, enzymatic models are studied to understand its preferential production. The principal results obtained from these studies are as follows. Seven mutants of the DGC PleD (a GGDEF containing-protein from Caulobacter crescentus) were constructed and the crystallographic structure of two of them was solved, showing that they are unlikely to bind the guanine moiety in its active site. Additionally, five mutants of XAC0610, another DGC from Xanthomonas citr, were constructed and their substrate specificities were evaluated. None of those mutants were able to use ATP as a substrate. Finally, seven different GGDEF domain-containing DGCs from different sources were expressed and purified and their enzymatic specificities were tested with several nucleotide triphosphates. One enzyme, GSU1658 from Geobacter sulfurreducens was particularly promiscuous and shown to produce c-di-GMP, c-di-AMP, c-di-IMP, c-di-2´dGMP, cGAMP, c-GIMP, and c-AIMP. Interestingly, XAC0610 was able to recognize 2´dGTP as substrate. Analysis of enzyme kinetics of XAC0610 in presence of 2´dGTP and/or GTP showed the preferential formation of the hybrid linear product pppGp2´dG. The second chapter present studies on cyanide metabolism in Bacillus with focus on the cyanide dihydratase of Bacillus safensis. Cyanide is widely used in industries due to its high affinity for metals. This same ability confers potent toxicity to this compound. Thus, industries must reduce the cyanide concentration from wastewater before its final disposal. Physical, chemical, and biological methods have been developed to achieve this goal, but knowledge about metabolic pathways and the biology of enzymes involved in cyanide degradation is still scarce. Here, the isolation of a Bacillus safensis strain from mine tailings in Peru is described. Classification of this strain was done through a comparative analysis of 132 core genomes of strains from the Bacillus pumilus group. Sequence analysis determined that a cyanide dihydratase (CynD, EC 3.5.5.1)) encoded in the genome of the isolated strain was likely the enzyme responsible for cyanide degradation. Confirmation of the cyanide degrading activity of CynD from this strain was achieved by cloning, expression and purification of the enzyme and its enzymatic characterization. CynD from this strain was active up to pH 9 and oligomerization patterns analyzed by SEC-MALS and electron microscopy showed that the enzyme forms large helical structures at pH 8 and smaller structures at higher pHs. Finally, we show that CynD expression is strongly induced in the presence of cyanide. The last two years of graduate studies were carried out in the context of the COVID-19 pandemic. Thanks to the large amount of publicly available genomic data, we were able to carry out studies on the worldwide dynamics of the spread of SARS-CoV-2 mutants forms. In the first year of the pandemic, genomic classification of 171,461 genomes showed the presence of five major haplotypes based on nine mutations. The worldwide distribution and the temporal evolution of frequency of these haplotypes was carefully analyzed. All the haplotypes were identified in the six regions analyzed (South America, North America, Europe, Asia, Africa, and Oceania); however, the frequency of each of them was different in each of these regions. As of September 30, 2020, haplotype 3 (or operational taxonomic unit 3, OTU_3) was the most prevalent in four regions (South America, Asia, Africa, and Oceania). OTU_5 was the most prevalent in North America and OTU_2 in Europe. Temporal dynamics of the haplotypes showed that OTU_1 became nearly extinct after 8 months of pandemic (November 2020). Other OTUs are still present in different frequencies all around the world, while currently generating new variants. Based on their temporal dynamics, a classification scheme of 115 SARS-CoV-2 mutations identified from 1,058,020 SARS-COV-2 genomes was also performed. Three types of temporal dynamics of mutations were identified: i) High-Frequency mutations are characterized by a rapid increase in frequency upon its appearance, ii) medium and iii) low-frequency mutations maintain mid or low-frequencies for several months and can be region-specific. Finally, we performed a correlation analysis of the effective reproduction number (Rt) of SARS-CoV-2 harboring the high-frequency mutation N501Y with the level of control measures adopted in specific jurisdictions. We show that Rt is negatively correlated with the level of control measures in eight of the nine countries analyzed. This negative correlation was similar when we analyzed the Rt of SARS-CoV-2 not-harboring N501Y. Thus, the control measures likely diminish the Rt of both SARSCoV-2 wild-type and N501Y

O presente trabalho está dividido em três capítulos sobre linhas de pesquisa diferentes desenvolvidas pelo autor durante o período de doutorado No primeiro capítulo, são apresentados estudos relacionados ao reconhecimento estrutural de substratos e análise enzimática de domínios GGDEF com atividade diguanilato ciclase (EC 2.7.7.65). As proteínas contendo domínios GGDEF estão relacionados à produção enzimática do segundo mensageiro c-di-GMP, a partir de duas moléculas de GTP, em procariotos. Esta molécula está principalmente envolvida na transição entre os estilos de vida móveis e sésseis, bem como vários outros fenótipos. Redundância e diversidade de sequências de domínio GGDEF aumentam a possibilidade de que outras funções enzimáticas ainda possam ser descobertas. Para testar esta hipótese, i) o efeito de mutações pontuais na estrutura e atividade enzimática dos domínios GGDEF é analisado, ii) a especificidade enzimática de domínios GGDEF de enzimas diferentes também é testada e iii) quando produtos não canônicos são detectados, modelos enzimáticos são estudados para entender sua produção preferencial. Como resultados mais importantes, sete mutantes do PleD (uma proteína contendo GGDEF) foram construídos e a estrutura cristalográfica de dois delas foi resolvida, mostrando que é improvável que eles liguem à porção guanina em seu sítio ativo. Além disso, cinco mutantes da proteína XAC0610 de Xanthomonas citri foram construídos e sua capacidade de usar ATP ou GTP como substrato foi avaliada. Nenhum desses mutantes foi capaz de usar ATP como substrato. Finalmente, sete outras proteínas contendo GGDEF foram purificadas e sua especificidade enzimática foi avaliada com vários trifosfatos de nucleotídeos. Uma enzima promíscua chamada GSU1658 mostrou produzir c-di-GMP, c-di-AMP, c-di-IMP, c-di-2´dGMP, c-GAMP, cGIMP e c-AIMP. Curiosamente, o XAC0610 foi capaz de reconhecer 2´dGTP como substrato. A análise da cinética enzimática de XAC0610 na presença de 2´dGTP e GTP mostrou a formação preferencial do produto linear híbrido pppGp2´dG. O segundo capítulo aborda estudos sobre o metabolismo do cianeto em Bacillus com foco na cianeto dihidratase de Bacillus safensis. O cianeto é amplamente utilizado nas indústrias devido à sua alta afinidade com os metais. Esta mesma capacidade confere toxicidade potente a este composto. Assim, as indústrias têm que reduzir a concentração de cianeto das águas residuais antes de sua disposição final. Métodos físicos, químicos e biológicos têm sido desenvolvidos para atingir esse objetivo, mas o conhecimento sobre as vias metabólicas e a biologia das enzimas envolvidas na degradação do cianeto ainda é escasso. Aqui, é descrito o isolamento de uma cepa de Bacillus safensis de rejeitos de minas no Peru. A classificação desta cepa foi feita através de uma análise comparativa de 132 core genomes de cepas do grupo de Bacillus pumilus. Em seguida, determinamos que uma cianeto dihidratase (CynD, EC 3.5.5.1) codificada no genoma da cepa isolada era provavelmente a enzima responsável pela degradação do cianeto. A confirmação da atividade degradante de cianeto de CynD desta cepa foi feita por clonagem, expressão e purificação da enzima e realização de caracterização enzimática. O CynD desta cepa é ativo até pH 9 e os padrões de oligomerização analisados por SEC-MALS mostraram que a enzima forma longas estruturas helicoidais em pH 8 e estruturas menores enquanto o pH aumenta. Finalmente, foi demonstrado que a expressão de CynD é fortemente induzida na presença de cianeto. Os últimos dois anos do doutorado foram realizados no contexto da pandemia COVID- 19. Vários laboratórios se dedicaram a gerar conhecimento para ajudar no combate à pandemia. Nesta situação e graças à grande quantidade de dados genômicos disponíveis publicamente, estudos sobre a dinâmica das mutações do SARS-CoV-2 foram realizados. No primeiro ano da pandemia, a classificação genômica de 171.461 genomas mostrou a presença de cinco haplótipos principais com base em nove mutações. A distribuição mundial e a mudança de frequência desses haplótipos foram analisadas cuidadosamente. Todos os haplótipos foram identificados nas seis regiões analisadas (América do Sul, América do Norte, Europa, Ásia, África e Oceania); no entanto, a frequência de cada um deles foi diferente em cada uma dessas regiões. Em 30 de setembro de 2020, o haplótipo 3 (ou unidade taxonômica operacional 3, OTU_3) era o mais prevalente em quatro regiões (América do Sul, Ásia, África e Oceania). OTU_5 foi o mais prevalente na América do Norte e OTU_2 na Europa. A dinâmica temporal dos haplótipos mostrou que OTU_1 parece perto da extinção após 8 meses de pandemia (novembro de 2020). Outros OTUs ainda estão presentes em diferentes frequências em todo o mundo, mesmo atualmente gerando novas variantes. Com base em sua dinâmica temporal, um esquema de classificação de 115 mutações SARS-CoV-2 identificadas a partir de 1.058.020 genomas SARS-COV-2 também foi feito. Três tipos de dinâmica temporal de mutações foram identificados: i) Mutações de alta frequência, ii) mutações de média frequência e iii) mutações de baixa frequência. Finalmente, foi analisada a correlação do número de reprodução efetiva (Rt) do SARS-CoV-2 que contém a mutação de alta frequência N501Y com o nível de medidas de controle, mostrando que seu Rt está negativamente correlacionado com o nível de medidas de controle em oito dos nove países analisados. Esta correlação negativa foi semelhante quando foi analisado o Rt de SARS-CoV-2 sem a mutação N501Y. Assim, as medidas de controle provavelmente diminuirão o Rt de SARS-CoV-2 tipo selvagem e N501Y

Capacidad olfativa y niveles de hormonas tiroideas en artesanos fabricantes de joyas expuestos al cianuro en Chordeleg, Ecuador / Alterations of sensitivity to contrast and stereopsis in workers exposed to aromatic hydrocarbons

Antecedentes: La exposición laboral crónica al cianuro se ha asociado con toxicidad en el sistema nervioso central caracterizada por alteraciones en la capacidad olfativa, así como disfunción de la glándula tiroides; se ha evidenciado lo anterior en individuos dedicados a oficios relacionados con la metalurgia y la joyería para extracción y purificación de metales como el oro y la plata, como los artesanos fabricantes de joyas en Chordeleg, Ecuador Objetivo: Evaluar la capacidad olfativa y funcionamiento de la glándula tiroides en artesanos fabricantes de joyas expuestos al cianuro en Chordeleg, Ecuador. Material y Métodos: Se estudiaron 69 individuos, realizando la medición los niveles séricos de hormonas tiroideas, la capacidad olfativa se evaluó por medio del Sniffin Stick Test, el análisis estadístico se realizó en el programa SPSS 15.0. Resultados: La capacidad olfativa de los participantes en este estudio expuestos al cianuro se encontró disminuida, hiposmia 33,3% y anosmia 27,5%, los valores medios para T3, T4 y TSH según la presencia o no de alteraciones en los niveles de tiocianato en orina no presentaron diferencias significativas entre los grupos, asimismo no se presentó una correlación entre estas variables. Conclusiones: No se demostraron los efectos de la exposición ocupacional crónica al cianuro sobre la capacidad olfativa y la función de la glándula tiroides de artesanos fabricantes de joyas en Chordeleg, Ecuador (AU)

Background: Chronic occupational exposure to cyanide has been associated with central nervous system toxicity characterized by alterations in olfactory capacity as well as dysfunction of the thyroid gland; has evidenced the above in individuals dedicated to trades related to metallurgy and jewelry for extraction and purification of metals such as gold and silver, as artisans jewelry manufacturers in Chordeleg, Ecuador. Objective: Evaluate the olfactory capacity and functioning of the thyroid gland in artisan jewelry manufacturers exposed to cyanide in Chordeleg, Ecuador. Materials and Methods: Sixty-nine individuals were studied and serum levels of thyroid hormones were measured. The olfactory capacity was evaluated by the Sniffin Stick Test, the statistical analysis was performed in the SPSS 15.0 program. Results: The olfactory capacity of participants in this study exposed to cyanide was decreased hyposmia 33.3% and anosmia 27.5%, mean values for T3, T4 and TSH according to the presence or not of alterations in the levels of thiocyanate in urine did not present significant differences between the groups, and there was no correlation between these variables. Conclusions: The effects of chronic occupational exposure to cyanide on the olfactory capacity and function of the thyroid gland of jewelry makers in Chordeleg, Ecuador, were not demonstrated (AU)

Local Targeting of NAD+ Salvage Pathway Alters the Immune Tumor Microenvironment and Enhances Checkpoint Immunotherapy in Glioblastoma.

The aggressive primary brain tumor glioblastoma (GBM) is characterized by aberrant metabolism that fuels its malignant phenotype. Diverse genetic subtypes of malignant glioma are sensitive to selective inhibition of the NAD+ salvage pathway enzyme nicotinamide phosphoribosyltransferase (NAMPT). However, the potential impact of NAD+ depletion on the brain tumor microenvironment has not been elaborated. In addition, systemic toxicity of NAMPT inhibition remains a significant concern. Here we show that microparticle-mediated intratumoral delivery of NAMPT inhibitor GMX1778 induces specific immunologic changes in the tumor microenvironment of murine GBM, characterized by upregulation of immune checkpoint PD-L1, recruitment of CD3+, CD4+, and CD8+ T cells, and reduction of M2-polarized immunosuppressive macrophages. NAD+ depletion and autophagy induced by NAMPT inhibitors mediated the upregulation of PD-L1 transcripts and cell surface protein levels in GBM cells. NAMPT inhibitor modulation of the tumor immune microenvironment was therefore combined with PD-1 checkpoint blockade in vivo, significantly increasing the survival of GBM-bearing animals. Thus, the therapeutic impacts of NAMPT inhibition extended beyond neoplastic cells, shaping surrounding immune effectors. Microparticle delivery and release of NAMPT inhibitor at the tumor site offers a safe and robust means to alter an immune tumor microenvironment that could potentiate checkpoint immunotherapy for glioblastoma. SIGNIFICANCE: Microparticle-mediated local inhibition of NAMPT modulates the tumor immune microenvironment and acts cooperatively with anti-PD-1 checkpoint blockade, offering a combination immunotherapy strategy for the treatment of GBM.

Impacto percibido en la salud de los mineros artesanales del municipio de Quinchía (Colombia) por el uso de mercurio y cianuro en el proceso de amalgamiento de oro / Perceived impact on the artisanal miner's health from quinchias municipality (Colombia) by the use of cyanide and mercury in the amalgamation process of gold

RESUMEN Objetivo Determinar el impacto percibido en la salud de los mineros artesanales del municipio de Quinchía (Colombia) por el uso de mercurio y cianuro en el proceso de amalgamiento de oro. Métodos Investigación cuantitativa, descriptiva, en una muestra de 28 mineros activos expuestos a cianuro y mercurio. Se caracterizó el proceso de amalgamiento de oro, se realizó una encuesta de percepción de síntomas y se efectuaron exámenes de laboratorio para detectar la concentración de mercurio y cianuro en la sangre. Resultados El 50% de los mineros llevan en el oficio entre 21 y 30 años, con una exposición de 2,6 horas/día al mercurio y cianuro. El 33% de los mineros presentan niveles de concentración de mercurio en la sangre entre 4 y 4,9 microgramos por litro (μg/L) y refieren síntomas en los sistemas nervioso y digestivo. Los resultados de cianuro en la sangre fueron negativos. Conclusiones Las concentraciones de mercurio en la sangre se asocian con el tiempo en el oficio, horas de exposición al mercurio y percepción de síntomas. Los resultados de cianuro en la sangre no son coincidentes con los síntomas referidos por los mineros. Pese a que, se reconoce la toxicidad de estas sustancias químicas, aún se emplean métodos tradicionales y prohibidos sin tener en cuenta los protocolos de seguridad y el uso de elementos de protección adecuados. Los mineros constantemente están expuestos a procedimientos que implican riesgos para la salud; refieren síntomas no diagnosticados y que podrían afectar el organismo a largo plazo. No se adoptan medidas de prevención y promoción.(AU)

ABSTRACT Objective Determine the Perceived Impact on the Artisanal Miner's Health from Quinchía's Municipality (Colombia) by the Use of Cyanide and Mercury in the Amalgamation Process of Gold. Methods Quantitative, descriptive research in a sample of 28 active miners exposed to cyanide and mercury. The process of gold amalgamation was characterized, a survey of symptom perception was carried out and laboratory tests were carried out to detect the concentration of mercury and cyanide in blood. Results 50% of the miners are in the trade between 21 and 30 years, with an exposure of 2.6 hours/day to mercury and cyanide. 33% of miners have levels of mercury concentration in blood between 4-4.9 micrograms per liter (μg/L), as well as refer to symptoms in the nervous and digestive systems. The results of cyanide in blood are negative. Conclusions Blood mercury concentrations are associated with time in the trade, hours of exposure to mercury and perception of symptoms. The results of cyanide in blood are not coincident with the symptoms reported by the miners. Although the toxicity of these chemical substances is recognized, traditional and prohibited methods are still used without taking into account safety protocols and the use of appropriate protection elements. Miners are constantly exposed to procedures that involve health risks, refer undiagnosed symptoms and that could affect the organism in the long term. Prevention and promotion measures are not adopted.(AU)

Leptin in the Commissural Nucleus Tractus Solitarii Increases the Glucose Responses to Carotid Chemoreceptors Activation by Cyanide.

Leptin is a protein hormone that plays a key role in the regulation of energy balance and glucose homeostasis. Leptin and all leptin receptor isoforms are present in the carotid bodies, but its precise function in glucose regulation and metabolism is not yet known. The aim of this study was to determine whether exogenous leptin, microinjected into the commissural nucleus tractus solitarii (cNTS), preceding sodium cyanide (NaCN) injection into the circulatory isolated carotid sinus (ICS), in vivo, modifies hyperglycemic reflex (HR) and brain glucose retention (BGR). In anesthetized Wistar rats (sodium pentobarbital, i.p. 3.3 mg/100 g/saline, Pfizer, Mex), arterial and venous blood samples were collected from silastic catheters implanted in the abdominal aorta and jugular sinus. Exogenous leptin (50 ng/20 nL of aCSF) or leptin vehicle (20 nL of aCSF) microinjected (stereotaxically) into the cNTS 4 min before NaCN (5 µg/100 g/50 µL saline into ICS) (experimental 1 [E1] and control 1[C1] groups, respectively) significantly increased HR and BGR compared with their basal values, but the increase was bigger in the E1 group. When leptin or aCSF were injected into the cNTS before saline (E2 and C2 groups, respectively) glucose responses did not vary when compared with their basal levels. Leptin and its receptors in the cNTS cells probably contribute to their sensitization during hypoxia.

Can excreted thiocyanate be used to detect cyanide exposure in live reef fish?

Cyanide fishing, where a solution of sodium or potassium cyanide is used to stun reef fish for easy capture for the marine aquarium and live fish food trades, continues to be pervasive despite being illegal in many countries and destructive to coral reef ecosystems. Currently, there is no easy, reliable and universally accepted method to detect if a fish has been exposed to cyanide during the capture process. A promising non-invasive technique for detecting thiocyanate ions, the metabolic byproduct excreted by exposed fish, has been reported in the literature. In an effort to validate this method, four cyanide exposure studies on Amphiprion ocellaris (common clownfish) were carried out over three years. Fish were either exposed to the same (25 ppm) or twice the concentration (50 ppm) as the previsouly published method. Over 100 water samples of fish exposed to cyanide were analyzed by reverse phase HPLC with a C30 column treated with polyethylene glycol and UV detector operating at 220 nm. No thiocyanate was detected beyond the analytical standards and positive controls prepared in seawater. As an alternate means of detecting thiocyanate, water samples and thiocyanate standards from these exposures were derivatized with monobromobimane (MBB) for LC-MS/MS analysis. Thiocyanate was detected in standards with concentrations as low as 0.6 µg/L and quantified to 1 µg/L, but thiocyanate could not be detected in any of the water samples from fish exposed to cyanide with this method either, confirming the HPLC results. Further, we calculated both the mass balance of thiocyanate and the resultant plausible dosage of cyanide from the data reported in the previously published method. These calculations, along with the known lethal dosage of cyanide, further suggests that the detection of thiocyanate in aquarium water is not a viable method for assessing fish exposure to cyanide.

Methylene blue counteracts cyanide cardiotoxicity: cellular mechanisms.

In adult left ventricular mouse myocytes, exposure to sodium cyanide (NaCN) in the presence of glucose dose-dependently reduced contraction amplitude, with ~80% of maximal inhibitory effect attained at 100 µM. NaCN (100 µM) exposure for 10 min significantly decreased contraction and intracellular Ca2+ concentration ([Ca2+]i) transient amplitudes, systolic but not diastolic [Ca2+]i, and maximal L-type Ca2+ current ( ICa) amplitude, indicating acute alteration of [Ca2+]i homeostasis largely accounted for the observed excitation-contraction abnormalities. In addition, NaCN depolarized resting membrane potential ( Em), reduced action potential (AP) amplitude, prolonged AP duration at 50% (APD50) and 90% repolarization (APD90), and suppressed depolarization-activated K+ currents but had no effect on Na+-Ca2+ exchange current ( INaCa). NaCN did not affect cellular adenosine triphosphate levels but depolarized mitochondrial membrane potential (ΔΨm) and increased superoxide (O2·-) levels. Methylene blue (MB; 20 µg/ml) added 3 min after NaCN restored contraction and [Ca2+]i transient amplitudes, systolic [Ca2+]i, Em, AP amplitude, APD50, APD90, ICa, depolarization-activated K+ currents, ΔΨm, and O2·- levels toward normal. We conclude that MB reversed NaCN-induced cardiotoxicity by preserving intracellular Ca2+ homeostasis and excitation-contraction coupling ( ICa), minimizing risks of arrhythmias ( Em, AP configuration, and depolarization-activated K+ currents), and reducing O2·- levels. NEW & NOTEWORTHY Cyanide poisoning due to industrial exposure, smoke inhalation, and bioterrorism manifests as cardiogenic shock and requires rapidly effective antidote. In the early stage of cyanide exposure, adenosine triphosphate levels are normal but myocyte contractility is reduced, largely due to alterations in Ca2+ homeostasis because of changes in oxidation-reduction environment of ion channels. Methylene blue, a drug approved by the U.S. Food and Drug Administration, ameliorates cyanide toxicity by normalizing oxidation-reduction state and Ca2+ channel function.

Amygdalin, quackery or cure?

BACKGROUND: The cyanogenic diglucoside, amygdalin, has gained high popularity among cancer patients together with, or in place of, conventional therapy. Still, evidence based research on amygdalin is sparse and its benefit controversial. PURPOSE: Since so many cancer patients consume amygdalin, and many clinicians administer it without clear knowledge of its mode of action, current knowledge has been summarized and the pros and cons of its use weighed. METHODS: A retrospective analysis was conducted for amygdalin relevant reports using the PubMed database with the main search term "Amygdalin" or "laetrile", at times combined with "cancer", "patient", "cyanide" or "toxic". We did not exclude any "unwanted" articles. Additionally, internet sources authorized by governmental or national institutions have also been included. SECTIONS: Individual chapters summarize pharmacokinetics, preclinical and clinical studies and toxicity. CONCLUSION: No convincing evidence showing that amygdalin induces rapid, distinct tumor regression in cancer patients, particularly in those with late-stage disease, is apparent. However, there is also no evidence that purified amygdalin, administered in "therapeutic" dosage, causes toxicity. Multiple aspects of amygdalin administration have not yet been adequately explored, making further investigation necessary to evaluate its actual therapeutic potential.

Determinants of cognitive performance in children relying on cyanogenic cassava as staple food.

While risk factors for konzo are known, determinants of cognitive impairment in konzo-affected children remain unknown. We anchored cognitive performance (KABC-II scores) to serum levels of free-thyroxine (free-T4), thyroid-stimulating hormone (TSH), albumin, and motor proficiency (BOT-2 scores) in 40 children including 21 with konzo (median age: 9 years) and 19 without konzo (median age: 8 years). A multiple regression model was used to determine variables associated with changes in KABC-II scores. Age (ß: -0.818, 95% CI: -1.48, -0.152) (p = 0.018), gender (ß: -5.72; 95% CI: -9.87, -1.57 for females) (p = 0.009), BOT-2 score (ß: 0.390; 95% CI: 0.113, 0.667) (p = 0.008), and free-T4 (ß: 1.88; 95% CI: 0.009, 3.74) (p = 0.049) explained 61.1 % of variation in KABC-II scores. Subclinical hypothyroidism was not associated with poor cognition. A crude association was found between serum albumin and KABC-II scores (ß: 1.26; 95 % CI: 0.136, 2.39) (p = 0.029). On spot urinary thiocyanate reached 688 µmol/l in children without konzo and 1,032 µmol/L in those with konzo. Female gender and low serum albumin are risk factors common to cognitive and proportionally associated motor deficits in children exposed to cassava cyanogens. The two types of deficits may share common mechanisms.

Normative concentrations of urine thiocyanate in cassava eating communities in Nigeria.

Exposure to cyanide is a major public health problem where highly cyanogenic cassava foods are consumed. Thiocyanate (SCN), the biomarker of exposure to cyanide is present in several foods, and produced endogenously. Concentrations of urine SCN were measured in endemic and non-endemic areas of ataxic polyneuropathy in Nigeria. Cassava food consumption in the endemic area was twice that of non-endemic areas. Geometrical mean (95% CI) urine SCN was 20 µmol/l (18-24) for no consumption of cassava foods, 56 µmol/l (49-64) for daily consumption, 56 µmol/l (48-65) for twice daily consumption and 85 µmol/l (62-117) for thrice daily consumption. 95th percentile reference limit was 125 µmol/l for no consumption of cassava food, but 360 µmol/l for thrice daily consumption. Urine SCN is a useful biomarker of exposure to cyanide from cassava foods. There is strong ecological association of exposure to cyanide and endemicity of ataxic polyneuropathy.

Carbon monoxide and cyanide toxicity: etiology, pathophysiology and treatment in inhalation injury.

Inhalation injury is most commonly associated with damage to the mucosal surfaces of the small and large airways after exposure to smoke and other products of incomplete combustion. Yet, there are far deadlier things lurking within the smoke than just the heat and particulate matter: carbon monoxide and cyanide. These two toxic substances are found in varying concentrations within the fire room and are associated with early on-scene death and in-hospital morbidity and mortality. Patients suffering from carbon monoxide and/or cyanide poisoning present with vague symptoms requiring an astute physician to make the diagnosis. Fortunately, the toxic effects related to exposure to these agents can be reversed with readily available antidotes.

Estabilidad de la hidroxocobalamina en agua para inyección como antídoto contra cianuros. Elaborado de Farmacia Militar / Stability of hydroxocobalamin in water for injection as cyanide antidote

Introducción: Los cianuros han sido utilizados como agentes de guerra química, y hoy se consideran una amenaza terrorista real. Son también la principal causa de muerte en la intoxicación por inhalación de humo de incendios en espacios cerrados. El éxito en el tratamiento de la intoxicación depende de la rapidez con la que se administren los antídotos, y con la que estos fijen el ión cianuro. La hidroxocobalamina parece ser un antídoto más apropiado que el nitrito sódico para el tratamiento empírico de la intoxicación por inhalación de humo y otras supuestas intoxicaciones por cianuros en el ámbito extra-hospitalario. Se ha estudiado la estabilidad de la hidroxocobalamina en agua para inyección a la dosis como antídoto contra cianuros y en cuatro tipos de envases diferentes. Material y Métodos: La solución inyectable se preparó por vía aséptica sin esterilización terminal, y según las especificaciones de la monografía oficial de la farmacopea de los Estados Unidos. Los cuatro tipos de envase primario utilizados fueron: ampollas de vidrio, bolsas y viales de polipropileno semirígido, y viales de plástico rígido fabricados en un copolímero olefínico complejo (COC). La determinación del contenido en hidroxocobalamina de las soluciones bajo estudio en función del tiempo, conservadas a 4º C, 25º C y 37º C, se llevó a cabo mediante cromatografía líquido-líquido de alta resolución y espectroscopia de absorción molecular. Se han utilizado otras técnicas analíticas complementarias para caracterizar la solución. Resultados: A 4º C el contenido en hidroxocobalamina de las muestras estudiadas permaneció invariable (media 99,81% ± 0,69%; p = 0,95; n = 7; t = 472 días). Resultados muy similares se obtuvieron para las muestras a 25º C (media 100,85% ± 1,79%; p = 0,95; n = 6; t = 353 días). A 37º C se produce una ligera disminución en el contenido en hidroxocobalamina de la solución envasada en ampollas (media = 92,87% ± 6,08%; p = 0,95; n = 4; t = 472 días). La solución envasada en bolsas de polipropileno sufrió un efecto de concentración por pérdida de agua a través del envase. En los dos tipos de viales estudiados el contenido en hidroxocobalamina de la solución se mantuvo en el rango de aceptación especificado en la farmacopea: 102,09% ± 0,47% a 4º C y 102,35% ± 0,60% a 37º C para los viales COC; 101,64% ± 2,16% a 4ºC y 101,19 ± 1,75% a 37º C, para los viales de polipropileno (p = 0,95). El autoclavado de la solución a 115ºC durante 30 minutos redujo el porcentaje de hidroxocobalamina a valores fuera del rango de conformidad (95-115%). Conclusiones: La solución inyectable de cloruro de hidroxocobalamina en agua para inyección a la concentración indicada como antídoto N.B.Q. contra cianuros, lista para administrar, es estable a temperaturas inferiores a 25º C, al menos durante un periodo de 15 meses. Por su inercia química y propiedades físicas, los viales de polipropileno constituyen el envase más adecuado para esta solución, que no puede ser autoclavada, y debe ser preparada por vía aséptica sin esterilización terminal (AU)

Background: Cyanide has been used as an agent for chemical warfare, and today it is also a credible terrorism threat agent. Cyanide poisoning is the first cause of death in victims of smoke inhalation from enclosed space fires. Successful treatment for acute cyanide poisoning depends upon rapid antidotes administration, and fixation of the cyanide ion by antidotes. Hydroxocobalamin seems to be a more appropriate antidote than sodium nitrite for empiric treatment of smoke inhalation and other suspected cyanide intoxication victims in the out-of-hospital setting. Stability of hydroxocobalamin in water for injection at cyanide antidote dose has been studied throughout the time and in four types of containers. Methods: The parenteral solution was prepared by aseptic procedures without terminal sterilization, and according to the United States Pharmacopoeia (USP) specifications. Four types of primary containers were used: glass ampoules, semi-rigid polypropylene bags and vials, and rigid plastic vials made of COC. Hydroxocobalamin content and other parameters from the studied solutions, conserved at 4º C, 25º C and 37º C was carried out using molecular spectrometry, liquid-liquid chromatography and others assays. Results: A 4º C the hydroxocobalamin content in the studied samples was invariable (mean 99,81% ± 0,69%; p = 0,95; n = 7; t = 472 days). Very similar results were obtained for samples at 25º C (mean 100,85% ± 1,79%; p = 0,95; n = 6; t = 353 days). At 37º C there was an small decrease in the ampoules hydroxocobalamin content (mean = 92,87% ± 6,08%; p = 0,95; n = 4; t = 472 days). The solution in polypropylene bags suffered a concentration due to water permeation through the container. Both types of vials had hydroxocobalamin contents in the USP specifications (95-115%). Steam sterilization at 115º C for 30 minutes turned hydroxocobalamin content out of specifications. Conclusion: The parenteral solution of hydroxocobalamin in water for injection at the dose of NBC cyanide antidote, ready to use, is stable at temperature below 25ºC, at least for 15 months. Because of the chemical inertia and physical properties, the polypropylene vials are the more appropriated containers for this parenteral solution, which has to be prepared by aseptic procedures without terminal sterilization (AU)

[Alternative means of drug therapy in cancer: letril].

Letril (amygdaline) is one of drugs of alternative therapy for cancer that is used over three decades and relates to cyanogenic glycosides received from kernels of various fruits (almonds, apricots, peaches, etc. The basis of suggestion of letril as antitumor agent is hypotheses about selective fermentative splitting of amygdaline in tumor cells with developing of cyanide that should cause to apoptosis as a result of aerobic glycolysis suppression. None of these assumptions found their experimental confirmation. In clinical trials there was established inefficiency of letril with a very high probability to develop severe cyanide intoxication. Despite obtained scientific data and absence of permission from the supervising institutions (FDA) letril is still advertised, produced and distributed as anti-tumor drug.

Etiology of Konzo, epidemic spastic paraparesis associated with cyanogenic glycosides in cassava: role of thiamine deficiency?

Konzo is a syndrome of symmetrical, non-progressive, non-remitting spastic paraparesis occurring in epidemic and endemic forms in several countries in Africa, invariably associated with monotonous consumption of inadequately processed bitter cassava roots (Manihot esculenta) with very minimal protein supplementation. Despite numerous epidemiological, clinical and biochemical studies by authors in several countries aimed at elucidating the etiological mechanisms of Konzo, the etiology remains unknown. High cyanide consumption with low dietary sulfur intake due to almost exclusive consumption of insufficiently processed bitter cassava roots was proposed as the cause of Konzo, but there has been no evidence of a causal association between cyanide consumption and Konzo. In this paper a new etiological mechanism of thiamine deficiency is presented, based on detailed review of the epidemiological, clinical and biochemical features of Konzo. It is postulated that in Konzo patients, a severe exacerbation of thiamine deficiency results from the inactivation of thiamine that occurs when, in the absence of dietary sulfur-containing amino acids; the sulfur in thiamine is utilized for the detoxification of cyanide consumed in improperly processed bitter cassava. Thiamine is known to be rendered inactive when the sulfur in its thiazole moiety is combined with hydrogen cyanide. This hypothesis may stimulate studies examining the role of thiamine in the etiology of Konzo, and may lead to the formulation of strategies for the prevention and treatment of this debilitating disease.

Tratamiento con hidroxicobalamina para la intoxicación por cianuro: una causa rara de pseudohematuria / Treatment with hydroxocobalamin for cyanide poisoning: a rare cause of pseudohematuria

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Safety and efficacy of NAD depleting cancer drugs: results of a phase I clinical trial of CHS 828 and overview of published data.

PURPOSE: Depletion of cellular nicotinamide adenine dinucleotide (NAD) by inhibition of its synthesis is a new pharmacological principle for cancer treatment currently in early phases of clinical development. We present new and previously published data on the safety and efficacy of these drugs based on early clinical trials. METHODS: A phase I clinical trial of CHS 828 in patients with advanced solid tumours was performed. Published clinical trials on NAD depleting drugs for cancer treatment were summarised for safety and efficacy. RESULTS: Seven patients with previously treated solid tumours received oral administration of CHS 828 in the dose range 20-80 mg once weekly for 3 weeks in 4 weeks cycles. Toxicity was dominated by gastrointestinal symptoms including nausea, vomiting, diarrhoea, constipation, subileus and gastric ulcer. One patient had thrombocytopenia grade 2. There were two cases each of grade 3-4 hyperuricemia and hypokalemia. Safety and efficacy of the NAD depleting drugs CHS 828 and FK866 have been reported from four phase I clinical trials, including a total of 97 patients with previously treated solid tumours. Outstanding toxicity reported was thrombocytopenia and various gastrointestinal symptoms. No objective tumour remission has been observed in the total of 104 patients treated in the above early trials. CONCLUSIONS: Critical toxicity from NAD depleting cancer drugs to consider in future trials seems to be thrombocytopenia and various gastrointestinal symptoms. Efficacy of NAD depleting drugs when used alone is expected to be low.

Cyanide poisoning in the post-transplantation patient-a cautionary tale.

There have been few reported cases of cyanide toxicity following treatment with sodium nitroprusside. We report on the case of a paediatric patient who had received sodium nitroprusside for intractable hypertension in the post-operative period, resulting in cyanide toxicity. Treatment with sodium thiosulphate, sodium nitrate and haemodialysis resulted in the elimination of cyanide from the circulation. The patient made a full recovery with no neurological sequelae.

Cardiopulmonary bypass, hemolysis, and nitroprusside-induced cyanide production.

BACKGROUND: Cyanide toxicity is a complication of sodium nitroprusside administration. Cardiac surgery may increase the risk of cyanide toxicity, because hemolysis during cardiopulmonary bypass (CPB) may catalyze the release of free cyanide from sodium nitroprusside. METHODS: We obtained serial blood specimens from 25 cardiac surgical patients during CPB. Plasma specimens were analyzed for free hemoglobin concentration and ability to generate free cyanide anion upon exposure to sodium nitroprusside. RESULTS: Hemolysis based on plasma-free hemoglobin concentration increased over time during CPB at an average rate of 0.27 mg x dL(-1) x min(-1) (P < 0.001). The concentration of free cyanide generated by the addition of sodium nitroprusside to the plasma samples was directly related to the plasma-free hemoglobin concentration (P < 0.001). CONCLUSION: CPB-associated hemolysis and free hemoglobin release accelerated the immediate release of free cyanide from sodium nitroprusside. These in vitro findings suggest that cardiac surgical patients may be at increased risk of cyanide toxicity in response to the perioperative administration of sodium nitroprusside.