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Lethal Effects (lethal + effects)

Distribution by Scientific Domains

Life Sciences	61%
Medical Sciences	22%

Selected Abstracts

Differences in the Rapid Knockdown and Lethal Effects of Aerosol Formulations against German Cockroach (Blattaria, Blattellidae) Strains

ENTOMOLOGICAL RESEARCH, Issue 4 2002
Dong-Kyu LEE
ABSTRACT The knockdown and lethal efficacies of five aerosol formulations including Combat Speed® (AIs: 0.1 % imiprothrin and 0.3% cyphenothrin), Raid Power® (AIs: 1.0% pyrethrin and 0.2% permethrin), Home Keeper®, (AIs: 0.2% tetramethrin and 0.3% permethrin), Super Killer® (AIs: 0.32% tetramethrin and 0.08% bioresmethrin), and Perma Kill-K® (AIs: 0.3% dichlorvos and 0.1% tetramethrin) against five strains of the German cockroach, Blattella germanica (L.) were assessed. The results show that the mean value of KT50 (5.4 sec.) of Combat Speed® was 4.5 and 3.1-folds lower than those of Perma Kill-K® and Home Keeper®, respectively. The mean value of KT90 (9.0 sec; slope = 10.02) of Combat Speed® was 3.8 to 5.8-folds lower than Perma Kill-K®, Supper Killer® and Home Keeper®. As lethal effects, the mean value of LT50 (17.3 sec.) of Combat Speed® was over 26 folds lower than Supper Killer® and Perma Kill-K®. The mean value of LT90 (32.9 sec.) of Combat Speed® was 37.4 and 15.1-folds lower than those of Supper Killer® and Perma Kill-K®, respectively. In general, Combat Speed® and Raid Power® were considered the insecticide aerosols with faster knockdown and higher lethal effects than Supper Killer®, Perma Kill-K®, and Home Keeper® against five strains of German cockroaches in Korea. Also, the knockdown and lethal effects of Supper Killer®, Perma Kill-K®, and Home Keeper® were highly variable depends on the strains. [source]

Field evidence of trait-mediated indirect interactions in a rocky intertidal food web

ECOLOGY LETTERS, Issue 2 2002
Geoffrey C. Trussell
Studies on the implications of food web interactions to community structure have often focused on density-mediated interactions between predators and their prey. This approach emphasizes the importance of predator regulation of prey density via consumption (i.e. lethal effects), which, in turn, leads to cascading effects on the prey's resources. A more recent and contrasting view emphasizes the importance of non-lethal predator effects on prey traits (e.g. behaviour, morphology), or trait-mediated interactions. On rocky intertidal shores in New England, green crab (Carcinus maenas) predation is thought to be important to patterns of algal abundance and diversity by regulating the density of herbivorous snails (Littorina littorea). We found, however, that risk cues from green crabs can dramatically suppress snail grazing, with large effects on fucoid algal communities. Our results suggest that predator-induced changes in prey behaviour may be an important and under-appreciated component of food web interactions and community dynamics on rocky intertidal shores. [source]

Differences in the Rapid Knockdown and Lethal Effects of Aerosol Formulations against German Cockroach (Blattaria, Blattellidae) Strains

Evaluation of the radioprotective effect of Liv 52 in mice

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 7 2006
Ganesh C. Jagetia
Abstract Liv 52 is a mixture of botanicals that is used clinically to treat various hepatic disorders. In this study, the radioprotective activity of Liv 52 was evaluated in mice given whole-body exposure to different doses of ,-radiation. In addition, a series of studies was conducted to explore the mechanism of radioprotection. Radioprotection was evaluated by the ability of Liv 52 to reduce both the frequency of bone marrow micronucleated erythrocytes and the lethality produced by 60Co ,-radiation. Mice were treated by oral gavage once daily for seven consecutive days with 500 mg/kg body weight Liv 52 or carboxymethylcellulose vehicle prior to radiation. Micronucleated polychromatic erythrocytes (MPCEs), micronucleated normochromatic erythrocytes (MNCEs), and the PCE/NCE ratio were measured at 0.25,14 days after exposure to whole-body radiation doses of 0, 0.5, 1.5, 3.0, or 4.5 Gy; animal survival was monitored after doses of 7, 8, 9, 10, 11, or 12 Gy. Pretreatment of mice with Liv 52 significantly reduced the frequency of radiation-induced MPCEs and MNCEs. Irradiation reduced the PCE/NCE ratio in a dose-related manner for up to 7 days following irradiation; Liv 52 pretreatment significantly mitigated against these reductions. Liv 52 treatment also reduced the symptoms of radiation sickness and increased mouse survival 10 and 30 days after irradiation. Liv 52 pretreatment elevated the levels of reduced glutathione (GSH), increased the activities of glutathione transferase, GSH peroxidase, GSH reductase, superoxide dismutase, and catalase, and lowered lipid peroxidation (LPx) and the activities of alanine amino transferase and aspartate aminotransferase 30 min after exposure to 7 Gy of ,-radiation. Liv 52 pretreatment also reduced radiation-induced LPx and increased GSH concentration 31 days following the exposure. The results of this study indicate that pretreatment with Liv 52 reduces the genotoxic and lethal effects of ,-irradiation in mice and suggest that this radioprotection may be afforded by reducing the toxic effects of the oxidative products of irradiation. Environ Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source]

Early signs of lethal effects in Daphnia magna (Branchiopoda, Cladocera) exposed to the insecticide cypermethrin and the fungicide azoxystrobin

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010
Ursula Friberg-Jensen
Abstract This study presents the effects of sublethal concentrations of pesticides cypermethrin and azoxystrobin on the activity of several physiological parameters of egg-carrying Daphnia magna studied using a video-image technique. Single tethered daphnids were continuously recorded for 24,h of pesticide exposure, and the activity of the heart, the filtering limbs, the mandibles, and the focal spine were subsequently analyzed. Acute toxicity tests based on the criteria of immobilization were performed on egg-carrying D. magna, and sublethal concentrations of 0.1, 1.0, and 10,µg/L cypermethrin and 0.5, 1.0, and 2.0,mg/L azoxystrobin were established. At a concentration as low as 0.1,µg/L cypermethrin, the 5% effective concentration after 24,h of exposure (EC5,24h), the activity of the focal spine increased and the filtering limb activity decreased. The activity of the mandibles was reduced by exposure to 1.0 (EC18,24,h) and 10,µg/L (EC41,24,h) cypermethrin, whereas heart activity increased at a concentration of 10,µg/L (EC41,24,h). With regard to azoxystrobin, the activity of all response parameters except the focal spine decreased by exposure to 0.5,mg/L (EC4,24h) azoxystrobin. The focal spine was not affected by azoxystrobin. The results show that physiological mechanisms important for ingestion of food in D. magna may be impaired by low concentrations of commonly used pesticides. Environ. Toxicol. Chem. 2010;29:2371,2378. © 2010 SETAC [source]

Effects of sublethal concentrations of bifenthrin and deltamethrin on fecundity, growth, and development of the honeybee Apis mellifera ligustica

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2010
Ping-Li Dai
Abstract Bifenthrin and deltamethrin have been widely used as pesticides in agriculture and forestry and are becoming an increasing risk to honeybees. The honeybee, Apis mellifera ligustica, is widely recognized as a beneficial insect of agronomic, ecological, and scientific importance. It is important to understand what effects these chemicals have on bees. Effects of two pesticides at sublethal concentrations on fecundity, growth, and development of honeybees were examined with the feeding method for a three-year period (2006,2008). It was shown that both bifenthrin and deltamethrin significantly reduced bee fecundity, decreased the rate at which bees develop to adulthood, and increased their immature periods. The toxicity of bifenthrin and deltamethrin on workers of Apis mellifera ligustica was also assessed, and the results from the present study showed that the median lethal effects of bifenthrin and deltamethrin were 16.7 and 62.8,mg/L, respectively. Environ. Toxicol. Chem. 2010;29:644,649. © 2009 SETAC [source]

Toxicity and fate of two munitions constituents in spiked sediment exposures with the marine amphipod Eohaustorius estuarius

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2005
Gunther Rosen
Abstract The lethal toxicity of the explosive compounds 14C-labeled 2,4,6-trinitrotoluene (TNT) and nonradiolabeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to the estuarine amphipod Eohaustorius estuarius was investigated in 10-d spiked sediment exposures. The 10-d median lethal concentration (LC50) was determined using the sum molar initial concentration of TNT, ami-nodinitrotoluenes (ADNTs), and diaminonitrotoluenes (DANTs), as determined by high-performance liquid chromatography (HPLC), and collectively referred to as HPLC-TNT*. Despite expectations of higher toxicity in sandy sediment (Yaquina Bay [YB], OR, USA) compared to relatively fine-grained sediment (San Diego Bay [SDB], CA, USA), LC50 values were similar: 159 and 125 ,mol/kg, for YB and SDB sediments, respectively. When expressed as the sum of TNT and all its degradation products (14C-TNT*), LC50s were approximately two times the corresponding LC50s determined by HPLC. The HPLC-TNT* fraction likely corresponds to the most bioavailable and toxic transformation products. The concentrations of 14C-TNT* in tissues were substantially higher than those for HPLC-TNT*, suggesting that compounds other than TNT and its major aminated transformation products were prevalent. Critical body residues were similar for exposures to SDB (11.7 ,mol/kg) and YB sediments (39.4 ,mol/kg), despite marked differences in the nature of compounds available for uptake in the exposure media. The critical body residues for E. estuarius are lower than those reported for other aquatic invertebrates (83,172 ,mol/kg). Unlike observations for TNT, RDX was only loosely associated with SDB sediment, with near complete recovery of the parent compound by chemical analysis. Exposure to RDX did not result in significant mortality even at the highest measured sediment concentration of 10,800 ,mol/kg dry weight, nor tissue concentrations as high as 96 ,mol/kg wet weight. The lack of RDX lethal effects in this study is consistent with results reported for other invertebrate species. [source]

The effect of ocean acidification and temperature on the fertilization and embryonic development of the Sydney rock oyster Saccostrea glomerata (Gould 1850)

GLOBAL CHANGE BIOLOGY, Issue 9 2009
LAURA M. PARKER
Abstract This study investigated the synergistic effects of ocean acidification (caused by elevations in the partial pressure of carbon dioxide pCO2) and temperature on the fertilization and embryonic development of the economically and ecologically important Sydney rock oyster, Saccostrea glomerata (Gould 1850). As pCO2 increased, fertilization significantly decreased. The temperature of 26 °C was the optimum temperature for fertilization, as temperature increased and decreased from this optimum, fertilization decreased. There was also an effect of pCO2 and temperature on embryonic development. Generally as pCO2 increased, the percentage and size of D-veligers decreased and the percentage of D-veligers that were abnormal increased. The optimum temperature was 26 °C and embryonic development decreased at temperatures that were above and below this temperature. Abnormality of D-veligers was greatest at 1000 ppm and 18 and 30 °C (,90%) and least at 375 ppm and 26 °C (,4%). Finally prolonged exposure of elevated pCO2 and temperature across early developmental stages led to fewer D-veligers, more abnormality and smaller sizes in elevated CO2 environments and may lead to lethal effects at suboptimal temperatures. Embryos that were exposed to the pCO2 and temperature treatments for fertilization and embryonic development had fewer D-veligers, greater percentage of abnormality and reduced size than embryos that were exposed to the treatments for embryonic development only. Further at the elevated temperature of 30 °C and 750,1000 ppm, there was no embryonic development. The results of this study suggest that predicted changes in ocean acidification and temperature over the next century may have severe implications for the distribution and abundance of S. glomerata as well as possible implications for the reproduction and development of other marine invertebrates. [source]

Non-lethal effects of predation in birds

IBIS, Issue 1 2008
WILL CRESSWELL
Predators can affect individual fitness and population and community processes through lethal effects (direct consumption or ,density' effects), where prey is consumed, or through non-lethal effects (trait-mediated effects or interactions), where behavioural compensation to predation risk occurs, such as animals avoiding areas of high predation risk. Studies of invertebrates, fish and amphibians have shown that non-lethal effects may be larger than lethal effects in determining the behaviour, condition, density and distribution of animals over a range of trophic levels. Although non-lethal effects have been well described in the behavioural ecology of birds (and also mammals) within the context of anti-predation behaviour, their role relative to lethal effects is probably underestimated. Birds show many behavioural and physiological changes to reduce direct mortality from predation and these are likely to have negative effects on other aspects of their fitness and population dynamics, as well as affecting the ecology of their own prey and their predators. As a consequence, the effects of predation in birds are best measured by trade-offs between maximizing instantaneous survival in the presence of predators and acquiring or maintaining resources for long-term survival or reproduction. Because avoiding predation imposes foraging costs, and foraging behaviour is relatively easy to measure in birds, the foraging,predation risk trade-off is probably an effective framework for understanding the importance of non-lethal effects, and so the population and community effects of predation risk in birds and other animals. Using a trade-off approach allows us to predict better how changes in predator density will impact on population and community dynamics, and how animals perceive and respond to predation risk, when non-lethal effects decouple the relationship between predator density and direct mortality rate. The trade-off approach also allows us to identify where predation risk is structuring communities because of avoidance of predators, even when this results in no observable direct mortality rate. [source]

Processed kaolin as an alternative insecticide against the European pear sucker, Cacopsylla pyri (L.)

JOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2005
C. Daniel
Abstract:, Application of processed kaolin particle film (Surround® WP; Engelhard Corporation, Iselin, NJ, USA) repels insects without lethal effects; hence side effects on beneficial arthropods are low. Processed kaolin may be an alternative to broad-spectrum insecticides used against European pear sucker, Cacopsylla pyri (L.), in organic and conventional pear production. A small-plot field trial was conducted in spring 2003 to assess this hypothesis. Multiple applications of processed kaolin during the first flying period of C. pyri significantly reduced the number of nymphs compared to the untreated control. Processed kaolin protected pear trees at least as good as the standard organic insecticide rotenone. Since the effects on the summer population could not be assessed in this small-plot trial due to the high mobility of the adult C. pyri, a large-plot trial was conducted in 2004. Thereby, the processed kaolin showed a very high efficacy and the population of C. pyri was kept under a damaging level over the whole season. At the end of June the population density of C. pyri in the processed kaolin treated area was lower than in the IPM treated plot. In conclusion, kaolin shows promise as an alternative control for C. pyri in organic and IPM orchards. [source]

Compatibility of a natural enemy, Coleomegilla maculata lengi (Col., Coccinellidae) and four insecticides used against the Colorado potato beetle (Col., Chrysomelidae)

JOURNAL OF APPLIED ENTOMOLOGY, Issue 3 2004
É. Lucas
Abstract:, ,The toxicity of four insecticides used to control the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), imidacloprid (Admire®), cryolite (Kryocide®), cyromazine (Trigard®), and Bacillus thuringiensis var. tenebrionis (Novodor®), to one of its natural enemies, the 12-spotted lady beetle, Coleomegilla maculata lengi Timberlake (Coleoptera: Coccinellidae) was determined in the laboratory. Toxicity assays against C. maculata adults and larvae consisted of (1) topical applications and (2) exposures to treated foliage and prey, using concentrations up to 10 times the manufacturer's recommendations. Over a 6-day period, cyromazine (insect growth regulator) and B. t. var. tenebrionis (microbial insecticide) had no lethal effects on first and third instars C. maculata. For both larval and adult stages, cryolite (inorganic insecticide) caused very low predator mortality when topically applied and moderate mortality when ingested through contaminated eggs of Colorado potato beetles. Imidacloprid (systemic organic insecticide) was highly toxic to adult and larval C. maculata. Its estimated LD50 at 6 days following treatment, corresponded to 0.02,0.09 times the recommended field concentration, depending on the developmental stage and mode of contamination. These results indicate that integrated pest management programmes for Colorado potato beetles using imidacloprid or, to a lesser degree, cryolite, would be detrimental to C. maculata. Cyromazine and B. t. var. tenebrionis seem to present a better compatibility with the protection of C. maculata populations. [source]

Acute oral toxicity of colchicine in rats: effects of gender, vehicle matrix and pre-exposure to lipopolysaccharide

JOURNAL OF APPLIED TOXICOLOGY, Issue 5 2007
Paddy L. Wiesenfeld
Abstract The oral toxicity of a single administration by gavage (10, 20 or 30 mg kg,1 body weight) of colchicine (COL) was determined in young, mature male and female Sprague-Dawley rats. The effect of COL was evaluated in the presence or absence of additional treatment variables that included vehicle and lipopolysaccharide (LPS) pre-exposure. The vehicle for COL was either Half and Half cream (H & H) or saline, and each group included pretreatment with either saline or a low, minimally toxic dose (83 µg kg,1 body weight) of LPS. Colchicine toxicity in both male and female age-matched rats was characterized by progressively more severe dose-related clinical signs of toxicity. These included mortality, decreased body weight and feed intake during the first several days after dosing, with recovery thereafter in surviving animals. There were differences in the severity of the toxic response to COL between male and female rats. The most notable sex-related difference was in COL lethality. Female rats were two times more susceptible to the lethal effects of COL than male rats. Saline or H & H delivery vehicles did not result in any apparent qualitative or quantitative differences in COL toxicity. LPS pretreatment significantly potentiated COL lethality in both males and females, although the potentiation in males was greater than in females. LPS pretreatment modestly increased the COL induced anorexic effect in surviving males, but not in surviving female animals. LPS did not appear to modulate either the body weights or clinical signs of COL induced toxicity in surviving males or females. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A comparison of the potency of newly developed oximes (K027, K048) and commonly used oximes (obidoxime, HI-6) to counteract tabun-induced neurotoxicity in rats

JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2006
í Kassa
Abstract The neuroprotective effects of newly developed oximes (K027, K048) and currently available oximes (obidoxime, HI-6) in combination with atropine in rats poisoned with tabun at a sublethal dose (170 µg kg,1 i.m.; 80% of LD50 value) were studied. The tabun-induced neurotoxicity was monitored using a functional observational battery and an automatic measurement of motor activity. The neurotoxicity of tabun was monitored at 24 h and 7 days following tabun challenge. The results indicate that the oxime HI-6 in combination with atropine was not able to protect the rats from the lethal effects of tabun. Two non-treated tabun-poisoned rats and one tabun-poisoned rat treated with atropine combined with HI-6 died within 2 h. On the other hand, all other tested oximes combined with atropine allowed all the tabun-poisoned rats to survive 7 days following tabun challenge. Both newly developed oximes combined with atropine seem to be sufficiently effective antidotes for a decrease in tabun-induced neurotoxicity in the case of sublethal poisoning although they are not able to eliminate tabun-induced neurotoxicity completely. The neuroprotective efficacy of obidoxime in combination with atropine approached the potency of newly developed oximes but the ability of the oxime HI-6 to counteract tabun-induced acute neurotoxicity was significantly lower, especially at 24 h after tabun poisoning. Due to their neuroprotective effects, both newly developed oximes appear to be suitable oximes for the antidotal treatment of acute tabun poisoning. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Feeding responses of carabid beetles to dimethoate-contaminated prey

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2004
Alice L. Mauchline
Abstract 1,The feeding responses of Pterostichus madidus Fab., P. melanarius Illiger and Nebria brevicollis Fab. (Coleoptera: Carabidae) to dimethoate-contaminated prey were investigated in ,no-choice' and ,choice' feeding tests. 2,In the no-choice tests, starved beetles were presented with aphid prey treated with four concentrations of dimethoate. In the choice tests, treated and untreated prey were presented together and the feeding preferences of the starved beetles observed. 3,No avoidance or rejection behaviour was seen in any of the carabids in either of the tests, i.e. no discrimination of the treated and untreated prey was observed. 4,Sufficient dimethoate was consumed with the aphid prey to cause significant mortality levels in the carabids. 5,The concentrations of dimethoate used in these experiments are comparable to field exposure, so carabids feeding in treated fields and field margins could potentially suffer lethal effects via the indirect exposure route of consuming contaminated prey. [source]

Paramethoxyamphetamine (PMA) poisoning; a ,party drug' with lethal effects

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2003
S. Refstad
Among young people in Norway the recreational use of amphetamine derivatives seems to be increasing. Methylenedioxymethamphetamine (MDMA), known as ecstasy, is the dominant substance, having both stimulant and psychedelic properties. Depending on the illegal source of these so-called ,party drugs' the content and purity can vary. This case report describes the first lethal case of paramethoxyamphetamine (PMA) and paramethoxymethamphetamine (PMMA) intoxication reported in Norway. A 16-year-old male was admitted to a local hospital in a coma with seizures and hyperthermia after he had been found undressed and barefooted in a local forest (temperature 2°C). He was intubated and given supportive care. Blood chemistry revealed hypoglycaemia, hypocalcaemia and hyperkalaemia. Shortly after transfer to the central hospital he developed bradycardia with continuous seizures and asystole. Adverse effects of MDMA are well described and include serotonergic and sympathomimetic symptoms with hyperthermia, coagulopathy, rhabdomyolysis and acute kidney and liver failure. Case reports of PMA deaths collectively suggest PMA to be more toxic than MDMA. A delayed effect after intake of PMA compared with MDMA can lead to increased intake. Hypoglycaemia and hyperkalaemia may be specific to PMA poisoning. Increased thermo genesis will result in a search for cooling, which explains the attempt to undress and a desire to submerge in water. In a cool climate this behaviour itself can be lethal. Measures to treat seizures, hypoglycaemia, electrolyte anomalies and hyperthermia are the therapeutic goals. No specific treatment is available. [source]

Evaluations of toxicity of Turraeanthus africanus (Méliaceae) in mice

ANDROLOGIA, Issue 6 2009
D. Massoma Lembè
Summary Turraeanthus africanus (Meliacaeae) is known to possess a broad spectrum of pharmacological, medicinal and therapeutic properties. However, no extensive safety studies have been conducted on these extracts to date. The aim of this study was to evaluate toxicity of the aqueous extract of Turraeanthus africanus (Meliacaeae) after oral and intraperitoneal administration in mice. The acute toxicity was evaluated after single daily administration of the aqueous extract orally at doses of 0, 5, 10, 15, 20, 30 g kg,1 or by the intraperitoneal route at doses of 0, 3, 6, 9, 12 g kg,1 of raw material. The subacute toxicity was evaluated only by the intraperitoneal route for 6 weeks at doses of 1.5, 3, 6 g kg,1 of raw material. Oral doses up to 30 g kg,1 of the aqueous extract of Turraeanthus africanus (TA) did not produce mortality or significant changes in the general behaviour and gross appearance of internal organs of rats. However, the intraperitoneal administration of the aqueous extract of Turraeanthus africanus caused dose-dependent lethal effects. The acute intraperitoneal toxicity (LD50) of TA extract in mice was 7.2 g kg,1. In subacute toxicity in mice, after the intraperitoneal administration of TA extract for 6 consecutive weeks, the feed consumption was significantly affected at the dose 3 g kg,1 with P < 0.05 and at the dose 6 g kg,1 with P < 0.001 and consequently had significant effect with P < 0.05 in body weight of animals. Level of triglyceride of treated animals lowered at dose 1.5 g kg,1 with P < 0.001 and at dose 3 g kg,1 and 6 g kg,1 with P < 0.05. Total cholesterol level of treated animals lowered at dose 1.5 g kg,1 with P < 0.005 and at dose 3 and 6 g kg,1 with P < 0.001. HDL cholesterol level of treated animals lowered up to dose 6 g kg,1 with P < 0.05 while levels of LDL cholesterol, serum and tissue creatinine of treated animals lowered at dose 3 g kg,1 and dose 6 g kg,1 with P < 0.05. Serum protein level of treated animal enhanced at dose 1.5 g kg,1 and at dose 6 g kg,1 with P < 0.05 while tissue creatinine level of treated animal enhanced with P < 0.001. The histology of liver, kidney and lung of the treated mice indicated morphological change of these organs (data not shown). No significant difference was observed during treatment concerning the haematological parameters. The results suggest that the plant is not toxic through the oral route in mice and that parenteral administration should be avoided. [source]

Effects of lipopolysaccharide on vascular reactivity and mortality in rats

AUTONOMIC & AUTACOID PHARMACOLOGY, Issue 5-6 2002
J. P. L. Nunes
Summary 1 The effects of intraperitoneal (i.p.) lipopolysaccharide on vascular reactivity to noradrenaline in rat aorta under different conditions of passive tension, as well as on mortality in normotensive and hypertensive rats, were studied. 2 Concentration,response curves to noradrenaline were obtained in aorta rings, at two levels of passive tension: 3 and 0.5 g, from control and lipopolysaccharide-treated Wistar rats. Contractile responses were expressed as percentage of the maximal response to noradrenaline obtained in the beginning of the experiment at a resting tension of 2 g. The maxima were significantly larger (P < 0.05) at 3 g than at 0.5 g in both groups of rats: 117.8 vs. 62.3%, respectively, for control animals; 85.8 vs. 32.5%, respectively, for lipopolysaccharide-treated rats. 3 The 24-h mortality after the i.p. administration of lipopolysaccharide was lower in spontaneously hypertensive rats (1/12; 8%), when compared with control Wistar,Kyoto rats (5/11; 45%). However, mortality was higher in Wistar,Kyoto made hypertensive by 8-day administration of corticosterone (6/6; 100%). 4 We conclude that a differential sensitivity to noradrenaline of aortic smooth muscle at two different levels of passive tension is still present in lipopolysaccharide-treated animals. Chronic hypertension in SHR rats is associated with resistance to the lethal effects of lipopolysaccharide, whereas abrupt-onset hypertension induced by corticosterone leads to an increased mortality. 5 These results are compatible with the myofibrillary hypothesis, which explains vascular hyper-reactivity in chronic arterial hypertension, by postulating that a more favourable relative position (and/or proportion) for actin and myosin occurs, whereas in states of vascular hypo-reactivity, such as vasodilatory shock, the opposite phenomenon may exist. [source]

Neuroprotective Effects of Currently Used Antidotes in Tabun-Poisoned Rats

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2003
í Kassa
The tabun-induced neurotoxicity was monitored using a functional observational battery and an automatic measurement of motor activity. The neurotoxicity of tabun was monitored at 24 hr and 7 days after tabun challenge. The results indicate that atropine alone is not able to protect the rats from the lethal effects of tabun. Three non-treated tabun-poisoned rats and one tabun-poisoned rat treated with atropine alone died within 24 hr. On the other hand, atropine combined with all tested oximes allows all tabun-poisoned rats to survive at least 7 days following tabun challenge. Obidoxime combined with atropine seems to be the most effective antidotal treatment for the elimination of tabun-induced neurotoxicity in the case of lethal poisoning among tested antidotal mixtures. The antidotal mixture consisting of atropine and HI-6 is significantly less effective than the combination of atropine with obidoxime in the elimination of tabun-induced neurotoxicity in rats at 24 hr following tabun challenge. Pralidoxime in combination with atropine appears to be practically ineffective to decrease tabun-induced neurotoxicity at 24 hours as well as 7 days following tabun poisoning. Due to its neuroprotective effects, obidoxime seems to be the most effective and most suitable oxime for the antidotal treatment of acute tabun exposure among currently used oximes. Thus, the replacement of obidoxime by a more effective acetylcholinesterase reactivator for soman poisoning, the oxime HI-6, can to a small extent diminish the neuroprotective efficacy of antidotal treatment in the case of acute tabun poisonings. [source]