Complex pathogenetic therapy of experimental botulism

The study of survival and life span of mice and white rats upon the administration of LD50 of the toxin has shown that an antihypoxic agent--gutimine (50-200 mg/kg)--had a protecting effect in type C botulinum intoxication. A combined use of gutimine and 4-aminopyridine (1-5 mg/kg), facilitating a transmitter release in synapses, had a more marked protecting effect in botulinum intoxication. Due to the potentiation of the drugs effect during their combined application, the doses of each drug in the combination could be reduced.     

Na+, K+-ATPase activity and serotonin transport in the rat brain synaptosomes fractions after acute 1,2-dichloroethane intoxication and nicotinamide administration

Alterations of Na+,K+-ATPase activity and serotoninergic system functioning were investigated in brain synaptosomes fractions of rats under experimental acute 1,2-dichloroethane (DChE) intoxication. It was shown that Na+,K+-ATPase activity was markedly increased (by 41,8%) in a period of 24 h after DChE intoxication and decreased (by 27%) after 48 h intoxication. The level of [2-14C]-serotonin uptake by synaptosomes was progressively diminished after 24 and 48 h after DChE injection whereas the activity of monoamine uptake proved to be unchanged. Nicotinamide (200 mg/kg of body weight) was administered to rats subjected to DChE 1, 24 and 36 h after poisoning. The treatment of rats with nicotinamide resulted in some normalization of brain synaptosomal Na+, K+-ATPase activity and serotonin uptake controlled at 48 h after DChE intoxication.     

Effect of supplemental magnesium on the kidney levels of cadmium, zinc, and copper of mice exposed to toxic levels of cadmium

In this report, we present the results of our investigations on the effect of Mg pretreatment on Cd and bioelements (Cu and Zn) contents in kidney of mice exposed to acute and subacute Cd intoxication. Acute intoxication was performed on male Swiss mice given a single oral dose of 20 mg Cd/kg body weight and mice given the same dose of Cd but pretreated with 40 mg Mg/kg body weight. For subacute intoxication one group of mice was given 10 mg Cd/kg body weight every day, for 2 wk, and the other one received the same dose of Cd after oral Mg intake of 20 mg/kg body weight. Cd, Cu, and Zn content was determined in kidney by atomic absorption spectrophotometry. In acute Cd intoxication, Mg pretreatment resulted in significant decrease of Cd in kidney after 4 and 6 h, compared with animals given only Cd. Under the condition of subacute Cd intoxication, Mg supplementation reduced Cd kidney content after 2 wk for about 30%, compared with animals treated with Cd only. The effect of Mg on Cu and Zn kidney content was also beneficial.     

Zinc or Magnesium Supplementation Modulates Cd Intoxication in Blood,Kidney, Spleen,and Bone of Rabbits

The objective of this study was to examine the influence of oral supplementation with Zn or Mg on Cd content in the blood and organs of rabbits exposed to prolonged Cd intoxication. Rabbits were divided into the following groups: Cd group-received orally every day for 4 weeks 10 mg Cd/kg body weight (b.w.), Cd+Zn group and Cd+Mg group-exposed to Cd and supplemented with 20 mg Zn/kg b.w. or 40 mg Mg/kg b.w. 1 h after Cd treatment. Cd content in biological material was determined by atomic absorption spectrophotometry. Blood Cd concentration was determined in all investigated groups at time 0 and after 10, 14, 18, 22, 25, and 28 days, whereas Cd content in the brain, heart, lungs, liver, kidney, spleen, pancreas, skeletal muscle, and bone was determined after 28 days. Blood Cd concentration was significantly increased in all groups from the 14th day of Cd intoxication and lasted till the end of the experiment. Zn or Mg supplementation significantly reduced blood Cd content on the 18th and 25th days. Supplementation with Zn or Mg significantly decreased Cd concentration in the kidney, spleen, and bone and, in addition, Zn reduced Cd content in the brain. Supplementation with Zn or Mg in Cd-intoxicated rabbits caused similar reduction of blood Cd concentration; however, reduction of tissue Cd content was more pronounced in Zn- than in Mg-supplemented group.     

Protective effect of various antioxidants on the toxicity of sulphur mustard administered to mice by inhalation or percutaneous routes

Protective effect of various antioxidants, trolox (water soluble analogue of vitamin E), quercetin (bioflavonoid) and glutathione reduced (GSH), was studied following sulphur mustard (SM) intoxication. SM, a blistering agent was administered to Swiss albino female mice through inhalation (1 LC50=42.3 mg/m3 for 1 h duration; 14 days observation for mortality) and percutaneous (1 LD50=154.7 mg/kg; 7 days observation for mortality) routes. The antioxidants were administered three times at the dose of trolox, 500 microg/kg; quercetin, 5 mg/kg and GSH, 400 mg/kg body weight by intraperitoneal injection, one immediately following SM exposure, then once each day for 2 days after SM treatment. The effect of antioxidants on survival, markers of oxidative damage and purine metabolites was investigated. Survival study animals were observed for 14 days. Oxidative markers (in blood, liver and lung) and purine metabolites (in blood and urine) were investigated 72 h after SM treatment. Survival time increased significantly following trolox and quercetin treatments through the inhalation route. Significant decrease in GSH and increase in the level of malondialdehyde (MDA) indicated oxidative damage to liver and lung tissues following SM inhalation and percutaneous exposure. Blood and urinary uric acid, end product of purine metabolism showed an increased following both routes of exposures. The antioxidants, trolox and quercetin protected the liver and lung tissues from oxidative damage caused by SM exposure through inhalation and percutaneous routes. This study showed that antioxidants could enhance survival time, protect liver and lung from oxidative damage and reduce accumulation of purine metabolites in blood following SM intoxication.     

Electroencephalographic study of naloxone effects in the recovery of an acute alcoholic intoxication

Experimental assays analysing EEG changes during the recovery of an acute alcoholic intoxication were carried out in three groups of cats: 1) Recovery of acute alcoholic intoxication produced by continuous intravenous perfusion of ethanol, 0.06 g/kg/min, during 20 minutes. 2) Recovery of acute alcoholic intoxication by injecting naloxone (400 micrograms/kg), just after finishing alcohol perfusion. 3) Recovery of acute alcoholic intoxication by injecting naloxone (400 micrograms/kg), 15 min after finishing perfusion. Naloxone administered after an acute alcoholic intoxication worsens the recovery of EEG parameters; 1-2 (p less than 0.05), 1-3 (p less than 0.05).     

Single hair analysis of methamphetamine and amphetamine by solid phase microextraction coupled with in matrix derivatization

A sensitive method for detection of methamphetamine (MA) and amphetamine (AP) in human hair was developed using solid phase microextraction (SPME) and one-pot derivatization. MA and AP were directly derivatized to N-propoxycarbonyl derivatives in an aqueous solution by propylchloroformate in a one-pot reaction before extraction by SPME. The derivatives were extracted to a coating of SPME from a headspace of the vial. The adsorbed derivatives were thermally desorbed in the injection port of a gas chromatograph. Pentadeuterated MA was used as an internal standard. The absolute recoveries of MA and AP from the spiked hair were 2.80-17.5%, respectively. The calibration curves showed linearity in the range of 0.05-20 ng/0.08 mg/vial for MA and 0.1-20 ng/0.08 mg/vial for AP in hair. Detection limits (S/N = 3) of MA and AP were 0.02 and 0.05 ng/0.08 mg/vial. The coefficients of variation of intraday were 1.04-26.4%. Additionally, this proposed method was applied to segmental analysis in clinical and medico-legal cases of MA intoxication.     

The effect of low concentrations of sodium nitrites and nitrates on respiration and oxidative phosphorylation in rat liver mitochondria]

Nitrite incubation in mitochondria and nitrate intoxication of rats have been studied for their effect on aerobic energetic processes in the liver. Sodium nitrite in concentration of 2 mg/l causes an inhibition of ADP-stimulated respiration and provides uncoupling processes of oxidative phosphorylation and respiration in mitochondria, when adding succinate as a substrate. Low doses of nitrate in vivo promote oxygen economization in mitochondria. Intoxication of rats with nitrate in a dose of 50 mg/l for 30 days induces a decrease of the respiration rate after ADP-phosphorylation and an increase of the coefficient of oxidative phosphorylation efficiency (ADP/O). Intraperitoneal administration of adrenalin in a dose of 25 micrograms/100 g to rats after 30-day nitrate intoxication in a concentration of 10 mg/l induces no typical increase of ADP-stimulated respiration and rate of oxidative phosphorylation and succinate oxidation.     

The role of cernitins in cadmium effect on the absorption processes in rat small intestine

The effect of long-term intoxication of cadmium (administered subcutaneously in a dose of 1 mg Cd/kg of body weight once a week for one month) on the absorption of water, sodium, potassium, glucose, glycine and thiamine in the small intestine of rats was investigated. In addition, the influence of cernitins (special pollen extract) on the action of cadmium intoxication was tested. The cernitins were given by stomach pump in the form of an aqueous solution of Pollitabs Sport tablets in a dose of 1.5 mg of cernitin T-60 and 0.075 mg of cernitin GBX per individual twice a week for two weeks or four weeks according to the group of animals tested. The results indicated that long-term administration of cadmium increased the intestinal absorption of all tested substances. Meanwhile, the application of cernitins reduced the effects of cadmium intoxication upon intestinal absorption and the processes of absorption was close to normal.     

Regulatory properties of the rat heart adenylate cyclase in the course of toxic-infective shock caused by Yersinia pestis]

Influence of intravenously administered to rats murine toxin of Y. pestis in the dose of I mg/ml (LD100) on the regulatory properties of heart plasma membranes adenylate cyclase (AC) has been studied during the intoxication. It has been shown that basal, fluoride,- and 5-guanylyl imidodiphosphate-stimulated AC activity remained unchanged during the intoxication. Stimulation of AC by isoproterenol, glucagon and histamine did not change during the first two hours and significantly decreased after 5 hours of intoxication. Affinity of AC for the investigated hormones did not change through the experiments.     

Antioxidant effect of hydroxytyrosol (DPE) and Mn2+ in liver of cadmium-intoxicated rats

Liver TBARS formation in cadmium-intoxicated rats was completely reduced by administering a low amount of MnCl(2) (2 mg/kg b.w.) 1 h before intoxication. A similar antioxidant effect was first shown by hydroxytyrosol (2-(3,4-dihydroxyphenyl)ethanol, (DPE), a phenolic compound present in olive oil, given twice to rats (9 mg/kg b.w.) after cadmium administration. The antioxidant properties shown in vivo by both Mn(2+) and DPE were also active in vitro when rat liver microsomes were subjected to lipid peroxidation by cadmium or other prooxidant systems. The increase in liver glutathione concentrations occurring in cadmium-intoxicated rats, was also found, for the first time, 24 h after MnCl(2) administration. Unlike cadmium intoxication, which caused a higher formation of both glutathione and TBARS, Mn(2+) induced glutathione synthesis without any TBARS formation. The same situation was also observed when cadmium plus Mn(2+) or cadmium plus DPE was given to rats. Our data show that: (a). both DPE and low Mn(2+) concentrations may have an antioxidant effect in the livers of cadmium-intoxicated rats and (b). Mn(2+), like cadmium, induces liver glutathione synthesis and this effect is probably independent of TBARS formation.     

Effect of chronic intoxication and naloxone on the ethanol-induced increase in plasma corticosterone

Ethanol (0.5–4.0 g/kg) induced an immediate, dose-dependent rise in plasma corticosterone in the conscious, undisturbed male rat. Chronic intoxication for at least two days resulted in tolerance to this effect. Chronic intoxication also significantly elevated the morning trough levels of this steroid. Co-administration of naloxone (1 mg/kg) prevented the development of tolerance to the immediate stimulatory effect of ethanol but did not alter the elevated trough levels of corticosterone. Naloxene (1 mg/kg) did not alter the stimulatory effect of ethanol on corticosterone in ethanol-naive animals. These data suggest that the process of tolerance development to the ethanol-induced rise in corticosterone is mediated by an opiate receptor. Alterations in the ability of ethanol to stimulate corticosterone secretion may be a useful endpoint for future studies of tolerance development to ethanol.     

Lipid peroxidative damage on cadmium exposure and alterations in antioxidantsystem in rat erythrocytes: A study with relation to time

Cadmium induced lipid peroxidation (LPO) and the activity of antioxidantenzymes after the administration of a single dose of CdCl 2 (0.4 mg kg body wt, ip) was studied in rat erythrocytes.Cd intoxication increased erythrocyte LPO along with a decrease insuperoxide dismutase (SOD) up to three days of Cd treatment. Thedecrease in erythrocyte catalase (CAT) activity was marked within9 h of Cd intoxication. After three days of Cd treatment, LPOdecreased towards normal, along with an increase in erythrocyteSOC and CAT activity. Blood glutathione (GSH) decreased significantlywithin 24 h of Cd treatment, followed by an increase towards normal.Erythrocyte glutathione S-transferase (GST) activity increased up to10 days of Cd intoxication, probably in an attempt to reduce Cd toxicity.Serum glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase(SALP) and serum bilirubin increased up to 10 days of Cd intoxication.Blood urea increased significantly up to three days, followed by a decreasetowards normal. The results show that Cd induced LPO was associated with adecrease in antioxidant enzymes and GSH in erythrocytes; as these antioxidantsincrease in erythrocytes with recovery from Cd intoxication, the Cd inducedLPO reversed towards normal. The increase in the SGPT, SALP and serum bilirubincorrelated with LPO. The results suggest that Cd intoxication induces oxidativestress and alters the antioxidant system, resulting in oxidative damage torat erythrocytes. © Rapid Science 1998     

Marijuana: effects on pulse rate, subjective estimates of intoxication and multiple measures of memory

Twelve experienced marijuana users received marijuana cigarettes containing 10 mg Δ⁹-THC or placebo in two experimental sessions each separated by a one week interval. The effects of both treatments on pulse rate, subjective estimates of intoxication, multiple measures of memory including free, serial and delayed recall, final free recall, and recognition memory were assessed. Pulse rate and subjective ratings were elevated significantly following intoxication with active marijuana in comparison to placebo. Each of the three types of recall were significantly reduced following intoxication with marijuana but no differential effects of drug on recall condition were noted. Intrusion errors were elevated on the final free recall test following intoxication but recognition memory was unaffected.     

Ricin Toxicokinetics and Its Sensitive Detection in Mouse Sera or Feces Using Immuno-PCR

Background

Ricin (also called RCA-II or RCA₆₀), one of the most potent toxins and documented bioweapons, is derived from castor beans of Ricinus communis. Several in vitro methods have been designed for ricin detection in complex food matrices in the event of intentional contamination. Recently, a novel Immuno-PCR (IPCR) assay was developed with a limit of detection of 10 fg/ml in a buffer matrix and about 10-1000-fold greater sensitivity than other methods in various food matrices.

Methods and Findings

In order to devise a better diagnostic test for ricin, the IPCR assay was adapted for the detection of ricin in biological samples collected from mice after intoxication. The limit of detection in both mouse sera and feces was as low as 1 pg/ml. Using the mouse intravenous (iv) model for ricin intoxication, a biphasic half-life of ricin, with a rapid t_1/2α of 4 min and a slower t_1/2β of 86 min were observed. The molecular biodistribution time for ricin following oral ingestion was estimated using an antibody neutralization assay. Ricin was detected in the blood stream starting at approximately 6–7 h post- oral intoxication. Whole animal histopathological analysis was performed on mice treated orally or systemically with ricin. Severe lesions were observed in the pancreas, spleen and intestinal mesenteric lymph nodes, but no severe pathology in other major organs was observed.

Conclusions

The determination of in vivo toxicokinetics and pathological effects of ricin following systemic and oral intoxication provide a better understanding of the etiology of intoxication and will help in the future design of more effective diagnostic and therapeutic methods.     

Tetrathiomolybdate(VI) as an antidote in acute intoxication by copper(II) and other toxic metal ions

Tetrathiomolybdate(VI), MoS₄^2?, has been found to act as an effective antidote for acute copper(II) intoxication in mice. Both (NH₄)₂MoS₄ and Na₂MoS₄ were used for this purpose with approximately the same results. The sodium salt is less toxic (LD50 = 537 mg/kg, ip) than the ammonium salt (LD50 = 176mg/kg, ip). The sodium salt was found to be an effective antidote for acute intoxication for some divalent metal ions (Zn²⁺ and Ni²⁺), but not for others (Hg²⁺, Cd²⁺. The sodium salt was also ineffective as an antidote in acute intoxication by arsenic(III), antimony(III) and bismuth(III), and methylmercuric chloride.     

Effect of M and N-cholinoblockers on the excitability of the dorsal hippocampus in acute alcoholic intoxication

It has been established in chronic experiments on rabbits that acute alcohol intoxication increased the after-discharge thresholds in response to electrical stimulation of dorsal hippocampus. It has been shown that neurotropic agents selectively blocking M- or N-cholinoceptors exerted various effects. M-cholino-blocker methamizol (1 mg/kg, i. p.) decreased the excitability of dorsal hippocampus, potentiated EEG and behavioural effects of alcohol intoxication. N-cholinoblocker etherophen (IEM-506, 20 mg/kg, i. p.), on the contrary, increased the excitability of dorsal hippocampus and reduced behavioural effects of alcohol administration.     

The role of xanthine oxidase in paraquat intoxication.

The role of xanthine oxidase in the mechanism of paraquat toxicity was assessed by in vitro and in vivo experiments. Paraquat stimulated the reduction of cytochrome c by xanthine-xanthine oxidase system in vitro. Paraquat, when added in vitro, stimulated hypoxanthine-dependent superoxide production in the cytosol of rat lung. Tungsten-feeding inhibits xanthine oxidase activity in a variety of tissues in experimental animals. Its therapeutic effect on paraquat intoxication was studied in this paper. In rats fed a tungsten-enriched diet for 5 weeks prior to intraperitoneal injection of 50 mg/kg paraquat dichloride, the mortality decreased significantly compared with rats fed a standard diet. Pretreatment with oxypurinol (1000 mg/kg, s.c.) also ameliorated the paraquat toxicity in rats. We conclude that xanthine oxidase plays an important role in paraquat toxicity and that xanthine oxidase inhibitors may become antidotes for paraquat intoxication.     

Feeding and survival of Culicoides sonorensis on cattle treated with permethrin or pirimiphos-methyl

The persistence of permethrin (5% a.i.) and pirimiphos-methyl (27% a.i.), applied to the dorsum of calves in the field against Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae), was estimated using a hair-blood-feeding bioassay in the laboratory. Hair clippings were taken before treatment and 3, 7, 14, 21, 28, 42 and 56 days after treatment from the dorsum, side and belly of treated and control calves. Laboratory-reared insects were allowed to feed through thin hair layers and a parafilm membrane on sheep blood warmed using a water-jacketed feeder. Some intoxication after exposure to hair was noted up to 28 days after treatment with permethrin and up to 14 days after treatment with pirimiphos-methyl. Hair from the dorsum caused more intoxication for a longer period than hair from other body regions. Permethrin and pirimiphos-methyl applied to the back did not significantly reduce overall engorgement (body regions pooled) after treatment. Permethrin residues on hair remained far higher on the back than other body regions and were related to insect intoxication and reduction in engorgement in the laboratory. Residues on belly hair never exceeded 12p.p.m. and did not result in significantly reduced feeding at any time. Engorged insects that exhibited sublethal intoxication from feeding through permethrin-treated hair did recover and matured numbers of eggs comparable to controls. Field trials using treated and control calves and enclosure nets showed that dorsal applications of 5% permethrin were not effective in reducing engorgement, despite some intoxication. Vacuum samples from a calf showed that C. sonorensis fed primarily on the belly. A 0.2% permethrin application on the belly (250 ml) did result in > 80% reduction of C. sonorensis in the enclosure nets at 3 and 7 days after treatment, but activity had subsided by 10 days after treatment. The utility of insecticidal treatments for suppression of this vector is discussed.