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Background: Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac (DCF), form a significant group of environmental contaminants. When the toxic effects of DCF on plants are analyzed, authors often focus on photosynthesis, while mitochondrial respiration is usually overlooked. Therefore, an in vivo investigation of plant mitochondria functioning under DCF treatment is needed. In the present work, we decided to use the green alga Chlamydomonas reinhardtii as a model organism., Methods: Synchronous cultures of Chlamydomonas reinhardtii strain CC-1690 were treated with DCF at a concentration of 135.5 mg × L -1 , corresponding to the toxicological value EC50/24. To assess the effects of short-term exposure to DCF on mitochondrial activity, oxygen consumption rate, mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (mtROS) production were analyzed. To inhibit cytochrome c oxidase or alternative oxidase activity, potassium cyanide (KCN) or salicylhydroxamic acid (SHAM) were used, respectively. Moreover, the cell's structure organization was analyzed using confocal microscopy and transmission electron microscopy., Results: The results indicate that short-term exposure to DCF leads to an increase in oxygen consumption rate, accompanied by low MMP and reduced mtROS production by the cells in the treated populations as compared to control ones. These observations suggest an uncoupling of oxidative phosphorylation due to the disruption of mitochondrial membranes, which is consistent with the malformations in mitochondrial structures observed in electron micrographs, such as elongation, irregular forms, and degraded cristae, potentially indicating mitochondrial swelling or hyper-fission. The assumption about non-specific DCF action is further supported by comparing mitochondrial parameters in DCF-treated cells to the same parameters in cells treated with selective respiratory inhibitors: no similarities were found between the experimental variants., Conclusions: The results obtained in this work suggest that DCF strongly affects cells that experience mild metabolic or developmental disorders, not revealed under control conditions, while more vital cells are affected only slightly, as it was already indicated in literature. In the cells suffering from DCF treatment, the drug influence on mitochondria functioning in a non-specific way, destroying the structure of mitochondrial membranes. This primary effect probably led to the mitochondrial inner membrane permeability transition and the uncoupling of oxidative phosphorylation. It can be assumed that mitochondrial dysfunction is an important factor in DCF phytotoxicity. Because studies of the effects of NSAIDs on the functioning of plant mitochondria are relatively scarce, the present work is an important contribution to the elucidation of the mechanism of NSAID toxicity toward non-target plant organisms., Competing Interests: The authors declare that they have no competing interests., (© 2024 Harshkova et al.)

Cyanide is a potent neurotoxic substance that can initiate series of intracellular reactions leading to oxidativestress. To evaluate effect of sublethal administration of potassium cyanide (KCN) on sensorimotor functions and long termvisuo-spatial learning and memory in adult Swiss mice and possible ameliorative role of vitamins A and E. These vitaminsA and E (dietary) are antioxidants that have scavenging properties against free radicals and reactive oxygen species as aresult of oxidative stress induced by cyanide. Thirty-five mice weighing between 18-22 g were used for the study. Theanimals were randomly divided into five groups (n = 7) and exposed to sublethal concentration of potassium cyanide (10%LD50; 1.5 mg/kg). KCN was administered orally while vitamin A (25 mg/kg) and vitamin E (50 mg/kg) were administeredintra-peritoneal (IP) once daily for 28 days. Potassium cyanide (KCN) was first administered and after 10 minutes intervals,followed by vitamin A and then E after 5 minutes, vitamin E were administered across the different treatment groups. Micewere examined for signs of toxicity. Vitamins pre-treatment ameliorated toxic signs. In the dynamics of wire grid, coathanger and stationary beam test, the latency to fall in weeks 2 and 4 were statistically significant. In acquisition and retention,using elevated plus maze (EPM), KCN treated group recorded high transfer latencies in seconds (50.40±1.72 secs) and(57.60±0.93 secs) as compared to group IV (29.40±0.68 secs; 5.60±0.60 secs). Cyanide is a neurotoxin that affects motorfunctions with progressive decline in motor strength and coordination. KCN affects acquisition and retention memory whilepre-treatment with antioxidant vitamins A and E ameliorated these deficits.

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.

The aim of the present study was to determine the deleterious effects of prolonged oral cyanide insult on various organs and tissues in rabbits. For this purpose, 12 locally bred adult male rabbits were allocated into two groups of 6 viz. control and experimental. Rabbits in control group were offered feed only while the rabbits in experimental group received feed plus potassium cyanide (KCN) at 3 mg/kg body weight orally for a period of 40 days. None of the rabbit in both the groups demonstrated any of the gross changes in any organ on postmortem examination. Liver was normal in size, shape, texture and color. Kidneys were also normal in size and color. Histopathological examination revealed severe hepatocyte vacuolation and degeneration in liver of rabbits in experimental group. There was also excessive congestion in liver and bile duct of rabbits in experimental group. Kidneys of rabbits in experimental group demonstrated severe glomerular and tubular necrosis and congestion. In the tubular epithelial cells, pyknotic nuclei were also present. On the other hand, heart and pancreas of rabbits in both control and experimental group did not show any histopathological change in microscopic structures. In conclusion, prolonged oral cyanide administration could have harmful effects on liver and kidney functions.

The UK's Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method ("rinse-wipe-rinse") for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants., Competing Interests: The authors have declared that no competing interests exist.

Hydrogen sulfide is a highly toxic gas-second only to carbon monoxide as a cause of inhalational deaths. Its mechanism of toxicity is only partially known, and no specific therapy exists for sulfide poisoning. We show in several cell types, including human inducible pluripotent stem cell (hiPSC)-derived neurons, that sulfide inhibited complex IV of the mitochondrial respiratory chain and induced apoptosis. Sulfide increased hydroxyl radical production in isolated mouse heart mitochondria and F2-isoprostanes in brains and hearts of mice. The vitamin B12 analog cobinamide reversed the cellular toxicity of sulfide, and rescued Drosophila melanogaster and mice from lethal exposures of hydrogen sulfide gas. Cobinamide worked through two distinct mechanisms: direct reversal of complex IV inhibition and neutralization of sulfide-generated reactive oxygen species. We conclude that sulfide produces a high degree of oxidative stress in cells and tissues, and that cobinamide has promise as a first specific treatment for sulfide poisoning.

A novel total toxicity detection method based on a mediated biosensor system with flow injection (MB-FI) was developed to rapidly and reliably detect respiration inhibitors (i.e., As2O3, KCN, salicylic acid (SA), 2,4-dintirophenol (DNP)) in water. The mediated biosensor toxicity assessment using microorganisms immobilized in calcium alginate filaments can greatly simplify the testing process and save time. In the MB-FI system, ferricyanide together with a respiration inhibitor was injected into the bioreactor, inhibiting the respiration of the immobilized microorganisms. The degree of inhibition was measured by determining the ferrocyanide generated in the effluent, expressed as the 50% inhibition concentration (IC50). The IC50 values for the four respiration inhibitors obtained using this method were comparable to those obtained using the classic method, confirming that this approach is an alternative alert method. More importantly, this constructed biosensor system with flow injection will facilitate the application and commercialization of this toxicity monitoring technology., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Twelve adult rabbits bred locally were divided into two equal groups of 6; experimental and control groups. Rabbits in the experimental group were orally dosed with KCN at 3mg/kg body weight for 40 consecutive days. Members in control group were given placebo (distilled water) for the same period. Animals in both groups were offered feed at 90gm/kg/day while ample drinking water was available ad lib. Feed consumption and body weight of rabbits in both the groups were recorded. Blood samples were also drawn to determine various hematological parameters. Statistical analysis revealed a non-significant difference of total and daily feed intakes in rabbits of experimental and control groups. Whereas the feed efficiency of rabbits in the experimental group were significantly reduced (P<0.05) compared to controls. Likewise a significant decrease in body weight gain of rabbits in experimental group (P<0.05) was observed. A non-significant difference (P>0.05) was observed in leukocyte count, differential leukocyte count and platelets of rabbits in both the groups. Erythrocyte count, hemoglobin concentration, packed cell volume and mean corpuscular hemoglobin were significantly decreased in treated rabbits. It was concluded that chronic cyanide intake had a deleterious effect on feed efficiency, growth rate and blood components of rabbits.

This study evaluates the toxic effects of five substances (atropine, fenitrothion, potassium cyanide, mercuric chloride and lead nitrate) on the yeast Saccharomyces cerevisiae. It describes a new biological toxicity test based on inhibition of S. cerevisiae viability and compares it with two standard toxicity tests based on Daphnia magna mobility inhibition (EN ISO 6341) and Vibrio fischeri bioluminiscence inhibition (EN ISO 11348-2). The new biological test -S. cerevisiae lethal test - is cheaper and 24 times faster than the D. magna test. The test speed is comparable with the V. fischeri test but the new test is more sensitive for some substances. The test indicates reliably the presence of all used toxicants in water in concentrations which are significantly lower than the concentration in toxic or lethal doses for man. Therefore, this new toxicity test could be proposed for rapid detection of toxic substances in water., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The effect of lyophilised aqueous extract of Telfairia occidentalis (TO) on induced cyanide toxicity in rats was investigated. Twenty 3-week old male wistar albino rats were randomly distributed into one control and three treatment groups of five rats each: control group (group1), group treated with 3mg/kg body wt of cyanide only (group2), group treated with 3mg/kg body wt. each of cyanide and extract (group3), and a group treated with 3mg/kg Body wt of extract only (group4) were used for the investigation. Cyanide toxicity reduced both food and water intake (p<0.05), while the food intake was improved in group3, this effect of the extract on food was not observed on water intake. Cyanide reduced average body weight of rats significantly (p<0.05). The reduction effect of cyanide on body weight was countered by Telfairia occidentalis extract. The extract did not have an observable effect on rats' body weight. Ocular lesion was observed in 67% of rats in group2 . This ocular effect of cyanide was mitigated significantly by Telfairia occidentalis as only 17% of the rats in group3 had ocular lesion. Cyanide toxicity produced nasal discharge in 39% of the rat population in group2 while there was a partial but considerable reduction (21%) in the severity of nasal discharge in group 3. There was no significant difference (p>0.05) in the organ/body wt.ratio between the treatments and the control groups for all the organs examined in the study. Biochemical analysis of liver enzymes showed that cyanide (group2) damaged the liver as there was significantly elevated presence (p<0.05) of Aspartate aminotransferase (AST) and Alanine aminotransferase (ALP) above those of the control group. The damaging effect of cyanide on the liver was ameliorated by Telfairia occidentalis considerably.Histopathological effect of cyanide toxicity on the organs examined included multifocal degeneration and necrosis of the liver, mild kidney congestion and congestion of the brain. These effects were moderated mildly by Telfairia occidentalis. Group 4, treated with the vegetable alone had none of the observed histopathology in the organs examined. We concluded that lyophilised aqueous extracts of Telfairia occidentalis showed good potential as a safe antidote for cyanide poisoning when administered concomitantly or very shortly after ingestion of sub-lethal dose of cyanide. However, further bioassay guided fractionation and analytical studies are needed to identify the actual chemical compound or molecule in the vegetable responsible for or associated with the observed effects.

Cyanide is a potential suicidal, homicidal and chemical warfare agent. It produces histotoxic hypoxia following inhibition of cytochrome c oxidase, a terminal respiratory chain enzyme. The profound metabolic changes lead to neurotoxicity including alterations in the levels of neurotransmitters. The present study addressed the effect of acute exposure of lethal and sub-lethal doses of potassium cyanide (KCN; 0.75 or 2.0 LD50; po) on the levels of neurotransmitters in discrete brain regions of rats and its response to treatment with alpha-ketoglutarate (alpha-KG; 0.5 g/kg; po; -10 min) alone or with sodium thiosulphate (STS; 1.0 g/kg; ip; -15 min). KCN significantly decreased norepinephrine, dopamine and 5-hydroxytryptamine levels in different brain regions which were resolved by alpha-KG and/or STS. Corpus striatum and hippocampus were more sensitive as compared to cerebral cortex and hypothalamus. alpha-KG, a potential cyanide antidote alone or with STS showed neuroprotective effects against cyanide.

Background & Objective: Cerebral hypoxia is known to be involved in many neurodegenerative diseases such as Alzheimer's and cerebrovascular dementia. The present study was designed to investigate the effects of flavonoids from aerial part of Scutellaria baicalensis Georgi (SSF) on potassium cyanide (KCN) -induced hypoxic cytotoxicity in rat pheochromocytoma cell line PC12, and to understand the probable mechanism., Methods: The rat pheochromocytoma cell line PC12 was subjected to hypoxia by 200 microM KCN for 30 min. The cytotoxicity of KCN was assessed by cell viability assay, morphological observation, lactate dehydrogenase (LDH) release, malondialdehyde (MDA) production, and the activities of superoxide dismutase (SOD) and Na+-K+-ATPase measurements. The effects of SSF on the changes induced by KCN in PC12 cells were detected., Results: Treatment of PC12 cells with 200 micriM KCN for 30 min increased cell death when compared with control, as assayed by MTT reduction, morphological observation and lactate dehydrogenase release measurement. These cell lesions were accompanied by disorders in SOD and Na+-K+-ATPase activities as well as MDA production. In contrast, the PC12 cells pre-treated with SSF for 24 h prior to 200 microM KCN exposure have shown protection against hypoxic toxicity. The KCN - induced decreased cell viability and activities of SOD and Na+-K+-ATPase, as well as increased MDA production were reversed by SSF pre-treatment., Interpretation & Conclusion: SSF exerted neuroprotections against KCN - induced hypoxic cytotoxicity in PC12 cells and the probable mechanisms involved free radicals and energy metabolism. Our findings may have implications in future in the treatment of neurodegenerative diseases.

We previously demonstrated that tenuifoliside B and 3,6'-disinapoylsucrose in Polygalae Radix, the root of Polygala tenuifolia WILLDENOW, inhibited potassium cyanide (KCN)-induced hypoxia and scopolamine-induced memory impairment in mice. Because both ingredients have a common sinapoyl moiety in their structure, we inferred that the sinapoyl moiety could inhibit hypoxia and memory impairment. In the present study to clarify the hypothesis, sinapic acid inhibited KCN-induced hypoxia and scopolamine-induced memory impairment as well as tenuifoliside B and 3,6'-disinapoylsucrose did. In addition, sinapic acid inhibited decompression- or bilateral carotid artery ligation-induced hypoxia (or mortality) and CO2-induced impairment in mice, and basal forebrain lesion-induced cerebral cholinergic dysfunction (decreases in acetylcholine concentration and choline acetyltransferase activity) in rats. These results, taken together, suggest the possibilities that sinapic acid is not only a very important moiety in the pharmacological activities of tenuifoliside B and 3,6'-disinapoylsucrose but also a candidate for a cerebral protective and cognition-improving medicine.

Cytoplasm of mammalian glial cells was reported to contain Gomori-positive cytoplasmic granulation (GPCG), whose biological role is unknown. The present study attempted to discover conditions facilitating GPCG formation and to elucidate their relationship with sulfane sulfur metabolism. To address these problems, we investigated in vivo the effect of both allyl disulfide (DADS), occurring in garlic (sulfane sulfur donor) and cyanide (sulfane sulfur acceptor) on number of GPCG-containing glial cells in the mouse brain. In parallel, sulfane sulfur level and activity of rhodanese and 3-mercaptopyruvate sulfurtransferase (MpST) were determined in the mouse brain and liver. Cyanide caused a drop in GPCG number in the brain, while activity of sulfurtransferases and sulfane sulfur level remained unchanged. Slight but significant cyanide-induced rise in MpST activity was observed only in the liver, which indicates a possibility of enhancement of its detoxification in reaction with mercapropyruvate in this organ. DADS, a sulfur donor, increased GPCG number in the brain, whereas activity of sulfurtransferases and sulfane sulfur level did not change. However, in the liver, DADS elevated both sulfurtransferase activity and sulfane sulfur level. These observations suggest that DADS can constitute a source of sulfane sulfur for the liver, thereby activating anaerobic sulfur metabolism and sulfane sulfur transfer. Consequently, this leads to the increase in sulfane sulfur level in plasma, in which it is transported in the form of albumin hydropersulfides and can be used for cyanide detoxification or stored in glial cells as GPCG. Therefore, it is not excluded that GPCG observed in the brain of mice and other mammals can be a source and a store of sulfane sulfur in mammals.

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

The integrated method combining chemistry and toxicology, toxicity identification evaluation (TIE), was conducted to identify key toxicants in an effluent from a nitrogen fertilizer plant in China. Toxicity characterization, phase I of TIE, revealed that the suspected toxicant in the effluent was an anion that could be changed into a volatile acid. The results of toxicity identification and confirmation procedures indicated potassium cyanide to be the primary toxicant in the effluent.

Chronic exposure to cyanide has been associated with development of pancreatic diabetes, hypothyroidism, and several neurological diseases in both humans and animals. However, there is a limited number of experimental models for these pathologies. Thus, in the present study 0, 0.15, 0.3, or 0.6 mg KCN/kg body weight/day was administered for 3 months to 26 rats. On the last day, plasma samples were obtained for glucose, cholesterol, and thyroidal hormone measurement, and the pancreas, thyroids, and whole central nervous system were collected for histopathologic study. There were no significant difference in plasma concentrations of the substances measured between groups, and no lesions were found in the pancrease or thyroid. The CNS of experimental animals revealed the presence of spheroids on the ventral horn of the spinal cord, neuron loss in the hippocampus, damaged Purkinje cells, and loss of cerebellar white matter. In conclusion, cyanide administration could promote neuropathological lesions in rats without affecting pancreas or thyroid gland metabolism.

Background: Dihydropyridines block calcium channels; however, they also influence endothelial cells, which do not express calcium channels. We tested the hypothesis that nifedipine can prevent ischemia-induced endothelial permeability increases by inhibiting protein kinase C (PKC) in cultured porcine endothelial cells., Methods and Results: Ischemia was induced by potassium cyanide/deoxyglucose, and permeability was measured by albumin flux. Ion channels were characterized by patch clamp. [Ca2+]i was measured by fura 2. PKC activity was measured by substrate phosphorylation after cell fractionation. PKC isoforms were assessed by Western blot and confocal microscopy. Nifedipine prevented the ischemia-induced increase in permeability in a dose-dependent manner. Ischemia increased [Ca2+]i, which was not affected by nifedipine. Instead, ischemia-induced PKC translocation was prevented by nifedipine. Phorbol ester also increased endothelial cell permeability, which was dose dependently inhibited by nifedipine. The effects of non-calcium-channel-binding dihydropyridine derivatives were similar. Analysis of the PKC isoforms showed that nifedipine prevented ischemia-induced translocation of PKC-alpha and PKC-zeta. Specific inhibition of PKC isoforms with antisense oligodeoxynucleotides demonstrated a major role for PKC-alpha., Conclusions: Nifedipine exerts a direct effect on endothelial cell permeability that is independent of calcium channels. The inhibition of ischemia-induced permeability by nifedipine seems to be mediated primarily by PKC-alpha inhibition. Anti-ischemic effects of dihydropyridine calcium antagonists could be due in part to their effects on endothelial cell permeability.

It is becoming increasingly accepted that removal of cellular cholesterol occurs by at least two pathways, one involving the well-described aqueous diffusion mechanism and another promoted by lipid-free apolipoproteins. We compared the contribution of apolipoprotein-dependent and -independent pathways, taking into consideration the influence of cellular metabolism, on cholesterol efflux promoted by different extracellular acceptor types. The acceptors used were assumed to participate in only passive efflux by lipid-dependent mechanisms (phospholipid vesicles and trypsin-modified high density lipoproteins) or to stimulate efflux by apolipoprotein-dependent pathways (purified apolipoprotein A-I and high density lipoproteins). Apolipoprotein-mediated cholesterol efflux was only apparent in growth-arrested or cholesterol-enriched cells and required metabolic energy. In contrast, cholesterol efflux by apolipoprotein-depleted acceptors did not depend on cell growth state, cholesterol enrichment, or metabolic energy. Apolipoprotein-mediated efflux was not observed at temperatures below 22 degrees C, while apolipoprotein-independent efflux was only reduced by 50% at 4 degrees C compared with incubations at 37 degrees C. Additionally, apolipoproteins promoted a more rapid and larger decrease in intracellular cholesteryl esters when measured by changes in cholesteryl ester radioactivity, mass, or the pool of cholesterol available for esterification by acyl coenzyme A:cholesterol acyltransferase. Efflux of excess cellular cholesterol by an apolipoprotein-dependent pathway appears to involve specific cellular events consistent with the properties of an active transport pathway and distinguishable from cholesterol efflux by apolipoprotein-depleted acceptors through passive mechanisms.

A bacterial toxicity test method using the determination of growth inhibition of sewage bacteria within an incubation period of 6 hours will be standardized at ISO. A ring test was performed with 24 participants using 3.5-dichlorophenol and potassium cyanide as test substances. The analysis of the test results showed that the method is very accurate and appropriate for determining the bacterial toxicity of chemical compounds. Due to the results obtained 3.5-dichlorophenol was proposed as a reference substance.

The effects of chromium compounds on 3-O-methylglucose (3-O-MG) transport were studied in isolated rat adipocytes. Sodium chromate significantly stimulated 3-O-MG uptake into adipocytes in a dose-dependent manner without altering the equilibrium space of 3-O-MG in adipocytes. The stimulatory effect reached the maximum at 300 microM, and the effect was 60-70% of the maximal insulin effect that was obtained with 20 nM insulin. The chromate concentration achieving a half-maximal effect was estimated at 50 microM. The effect of the combination of 1 mM chromate and 20 nM insulin was equipotent to that of 20 nM insulin alone, which showed that these two effects were not additive. The stimulatory effects of 1 mM chromate and 20 nM insulin were entirely abolished in adipocytes deprived of ATP, which indicated that these effects were completely ATP-dependent. Judging from experiments using various chromium compounds, CrO4(2-) was responsible for the insulinomimetic action. These results indicate that the action of CrO4(2-) is exerted through a mechanism analogous to that of insulin action, and that CrO4(2-) is a novel and useful tool for studying issues involved in insulin actions.

Carp spermatozoa are immotile in seminal plasma or in saline solution of high osmolality (> 400 mosmol kg-1). These 'quiescent' spermatozoa initiate a progressive forward motility when transferred in freshwater or in saline solution with low osmolality (< 160 mosmol kg-1). In this study we investigated 'in vitro' the relationship between sperm ATP content (measured by bioluminescence) and sperm motility (analysed by videomicroscopy). Sperm ATP content remained high in the immobilizing medium (200 mM KCl, Tris 30 mM, pH 8.0) where no flagellar movement occurs. Dilution of these spermatozoa in the activating medium (45 mM NaCl, 5 mM KCl, Tris 30 mM, pH 8.0) triggered forward motility which varied with temperature. At 20 degrees C, sperm ATP content decreased rapidly during the progressive forward motility phase from 12 to 4 nmol/10(8) spermatozoa, concomitantly with decreases in velocity (130 to 10 microns s-1) and the beat frequency (50 to 7 Hz). An inhibitor of mitochondrial respiration (KCN 10 mM) produced a drop in sperm ATP content irrespective of the incubation medium (activating or immobilizing). A second phase of sperm motility in the activating medium was induced following a previous transfer of spermatozoa into a medium of high osmolality for a few minutes prior to the second phase. Within 10 minutes, spermatozoa recover 90% of the initial ATP level as well as forward motility. These results suggest that motility of carp spermatozoa depends on sperm ATP synthesized by mitochondrial respiration mainly stored before activation. In low osmolality conditions, the mitochondrial oxidative phosphorylation is unable to compensate for the ATP hydrolysis required to sustain motility.(ABSTRACT TRUNCATED AT 250 WORDS)

Background and Purpose: The hippocampus demonstrates a regional pattern of vulnerability to ischemic injury that depends on its characteristic differentiation and intrinsic connections. We now describe a model of ischemic injury using organotypic hippocampal culture, which preserves the anatomic differentiation of the hippocampus in long-term tissue culture., Methods: Ischemic conditions were modeled by metabolic inhibition. Cultures were briefly exposed to potassium cyanide to block oxidative phosphorylation and 2-deoxyglucose to block glycolysis. The fluorescent dye propidium iodide was used to observe membrane damage in living cultures during recovery., Results: 2-Deoxyglucose/potassium cyanide incubation resulted in dose-dependent, regionally selective neuronal injury in CA1 and the dentate hilus, which began slowly after 2 to 6 hours of recovery. Subsequent histological examination of cultures after 1 to 7 days of recovery demonstrated neuronal pyknosis that was correlated with the early, direct observation of membrane damage with propidium. Both propidium staining and histological degeneration were prevented by the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 when administered 30 minutes after the end of the exposure to 2-deoxyglucose and potassium cyanide. Tetrodotoxin, which blocks voltage-dependent sodium channels, had protective effects that were greatest during the period of 2-deoxyglucose and potassium cyanide incubation but also produced protection against the mildest conditions of metabolic inhibition when administered after 30 minutes of recovery., Conclusions: This in vitro model reproduced elements of the time course, regional vulnerability, and pharmacologic sensitivities of in vivo ischemic hippocampal injury. Inhibition of metabolism in organotypic culture provides a rapid, easily controlled injury and reproduces the in vitro pattern of hippocampal regional vulnerability to ischemia. It is the first in vitro model of ischemia to exhibit complete protection by delayed administration of an NMDA receptor antagonist during recovery from a brief insult. The protective effects of tetrodotoxin suggest that an early period of sodium entry into cells during and after ATP depletion may be responsible for the more prolonged period of toxic NMDA receptor activation.

(6R)-6-Hydroxy-, (6S)-6-hydroxy- and (18S)-18-hydroxyeburnamonines were obtained by microbial conversion of (-)-eburnamonine using Mucor circinelloides and Streptomyces violens. Their structures were determined by analyses of the mass, 1H- and 13C-NMR spectra. (-)-Eburnamonine and the three hydroxylated compounds showed cerebral protecting effects against potassium cyanide intoxication in mice.

Subcutaneous administration of cyanide significantly increased blood tyrosine levels of mice in a dose dependent manner. Tyrosine aminotransferase activity in liver of mice was significantly decreased in the presence of cyanide (8, 10, 20, 40, 50, 65, 80 and 100 microM), also in a concentration-dependent manner, with a positive correlation between the percentage increase of blood tyrosine levels and the percentage decrease of hepatic tyrosine aminotransferase activity. These results suggest that the increased tyrosine levels induced in blood by cyanide may be related to its inhibition of tyrosine aminotransferase activity in the liver. Cyanide decreased hepatic ATP content and increased blood ammonia levels and brain tyrosine in a dose-dependent manner. As it is known that hyperammonaemia increases the uptake of neutral amino acids such as tyrosine into the brain from blood, the mechanism by which tyrosine levels increase in the brain may be based on increases of both tyrosine and ammonia levels in blood.

Glycine protects renal tubule cells from cell death during adenosine triphosphate (ATP) depletion. Although the liver plays a key role in glycine metabolism, information is lacking regarding the effects of glycine on lethal hepatocellular injury. Thus, the aim of this study was to determine the potential cytoprotective role of glycine during ATP depletion of rat hepatocytes. Metabolic inhibition with 2.5 mmol/L potassium cyanide (KCN) was used to produce ATP depletion. Hepatocyte suspensions treated with KCN had a 2-hour viability of 5.9% +/- 2.0%, whereas cells treated with KCN in the presence of 2.0 mmol/L glycine had a viability of 80.2% +/- 1.5%, which was virtually identical to controls (81.5% +/- 1.9%). Glycine cytoprotection was dose dependent and amino acid specific. The cytoprotective effect of glycine was not mediated by protein synthesis, glycine mitochondrial metabolism, cytosolic acidosis, or preservation of either intracellular cellular glutathione or ATP. However, glycine did decrease total cellular proteolysis by 18% +/- 2%, 25% +/- 3%, and 33% +/- 1% after 1, 2, and 3 hours of KCN treatment, respectively (P less than 0.01). Inhibition of proteolysis by glycine was dose dependent over the same range as its cytoprotection. The results suggest that glycine protects against hepatocellular injury by inhibiting degradative proteolytic activity. It was concluded that proteolysis may be an important mechanism contributing to lethal injury of hepatocytes during ATP depletion.

To investigate the toxicity of potassium cyanide in fresh fruit and juice, male and female Wistar rats were orally dosed with fruit homogenates or juices containing 3 x LD50 of potassium cyanide. These were given in single doses at various intervals after spiking. The dosing solutions were analysed for cyanide using a cyanide test kit. There was a good correlation between the toxic signs in rats and the cyanide remaining in dosing solutions. The toxicity of spiked apple and honeydew melon diminished with time, while spiked grape and both grape and apple juices maintained their toxicity during the 4-hr studies. The pH of the samples both before and after spiking seemed to be an important factor in determining the toxicity.

Effects of eptazocine on cerebral metabolic changes due to a sublethal dose of KCN were investigated in mice. KCN (2 mg/kg, i.v.) induced a temporary loss of consciousness being moderated by eptazocine (1-10 mg/kg) in a dose-dependent manner. The KCN injection decreased the contents of phosphocreatine (PCr), ATP and glucose and increased the contents of AMP and lactate, resulting in a 34% decrease in energy charge potential (ECP) and an increase in lactate/pyruvate (L/P) ratio. Such changes were improved by eptazocine (10 mg/kg) and EKC (3 mg/kg), but not by pentazocine (10 mg/kg) and morphine (3 mg/kg), and the improving effect of eptazocine was completely inhibited by MR-2266 (3 mg/kg), a relatively selective opioid kappa-receptor antagonist. On the other hand, eptazocine (3, 10 mg/kg) was found to increase the glucose content in normal mice, but not to give significant changes in the contents of glycolytic metabolites and high-energy phosphates. These results suggest that eptazocine may improve anoxic changes in cerebral energy metabolism.

The heat produced by Ehrlich ascites carcinoma cells was measured microcalorimetrically to investigate the characteristics of the energetics of these cells. 2,4-Dinitrophenol and other inhibitors were used to obtain the standard thermograms. The heat level of starved Ehrlich ascites carcinoma cells (endogenous) was almost constant and linear and depended on the cell number used in the experiments (about 1 cal/1 X 10(8) cells/hr). The endogenous heat generation was suppressed strongly by potassium cyanide but not by iodoacetic acid or 2,4-dinitrophenol. On the other hand, heat evolution was directly related to the amount of glucose added to the medium but not to the number of cells (19 cal/mmol of glucose). The addition of iodoacetic acid markedly suppressed heat generation, but potassium cyanide did not. In contrast, glucose with dinitrophenol increased heat production markedly to about 10% higher than that of the control, possibly due to the uncoupled energy from oxidative phosphorylation. Malonic acid (1 mM) suppressed slightly the endogenous heat but caused a 15% reduction in exogenous heat. The amount of heat produced by the addition of glucose (19 cal/mmol) was equivalent to 40% of the theoretical value of energy released through glycolysis (47 cal/mmol). Thus, the heat produced by exogenous glucose appears to be mainly dependent on glycolysis.

Chronic implantation of surface coils on the skull has been developed to record 31P NMR spectra of the brain in unanesthetized rats. Intraperitoneal sublethal potassium cyanide doses induce strong and reversible changes in high-energy phosphate compounds in the brain, similar in part to those induced by ischemia. These effects are dose-dependent as far as phosphocreatine, inorganic orthophosphates and pH are concerned; ATP does not seem to be altered by KCN doses ranging from 3 to 5 mg/kg but starts decreasing at a dose of 6 mg/kg. The fraction of Mg2+ complexed ATP which could be estimated as about 90% was not affected by KCN intoxication. For high doses (6 mg/kg) a new peak, appearing on the upfield side of the inorganic phosphate peak, may correspond to an acidic compartment, the significance of which is discussed.

The influence of NKK-105 on the acute toxicity of strychnine nitrate, potassium cyanide, chloral hydrate, atropine, tetrodotoxin, mercuric chloride, cadmium chloride, lead acetate and arsenic trioxide were examined in rats. NKK-105 prolonged the time of death induced by strychnine, potassium cyanide and tetrodotoxin in acute toxicity. Survival time was prolonged in rats treated with the toxic metals by pretreatment with NKK-105. NKK-105 counteracted the lethal effect of strychnine, potassium cyanide, chloral hydrate, mercuric chloride and cadmium chloride. NKK-105 significantly decreased the acute toxicity of these drugs but the inhibitory effect was not observed in the acute toxicity of atropine, tetrodotoxin, lead acetate and arsenic trioxide.