急危重症眼镜蛇伤大鼠多项凝血指标动态变化

目的动态观察蛇伤后大鼠多项凝血指标、病理及皮下出血情况的改变,为蛇毒毒理及抗蛇毒制剂的研究提供实验数据。方法将SD大鼠注入2～4 LD50眼镜蛇毒造模,于注毒后不同时段(20～140 min)分别进行凝血功能、肝脏和肾脏病理等检测,处死大鼠后观察注毒部位皮下出血情况。结果大鼠注入4 LD50蛇毒20 min,凝血酶原时间(PT)、部分凝血酶原时间(APTT)延长;40 min时,纤维蛋白原(Fbg)明显下降;40 min后凝血功能逐渐回复至0 min水平。肾脏、肝脏组织见血管扩张、充血明显。注毒部位皮下出血范围于20～80min时最明显。2 LD50剂量组凝血功能的变化与4 LD50组相似,但其Fbg下降程度小于4 LD50组,皮下出血面积较4 LD50组小。结论眼镜蛇毒引起凝血功能改变,且其变化程度与剂量及注入时间密切相关。     

Short term effects of animal venoms on the mitotic index of the duodenal mucosa of albino rats.

Short term administration of the venoms of the snakes Naja haje, Naja nigricollis, and Cerastes vipera and of the scorpion Leiurus quinquestriatus on the mitotic index of the duodenal mucosal cells of the white rat, Rattus rattus, has been studied. All the venoms increased the number of dividing cells of the duodenal mucosa significantly. Naja haje crude venom was fractionated into three fractions. Fraction I had no effect on the mitotic index whereas fractions II and III increased it significantly. Treatment of rats with Naja haje venom fractions II and III after blocking the histamine or the serotonin receptors did not affect the stimulatory action of the two venom fractions on the mitotic index, which it increased significantly. It was suggested that the venoms of Naja haje, Naja nigricollis, Cerastes vipera, and Leiurus quinquestriatus and Naja haje venom fractions possessed a mitogenic activity. Fraction II of Naja haje venom acted through both the muscarinic and adrenergic receptors while fraction III acted on the adrenergic ones.     

乙醇对中华眼镜蛇毒毒性的影响

目的为了探索乙醇对眼镜蛇毒毒性的影响。方法将眼镜蛇毒不同浓度致死量经不同浓度乙醇体外处理后,分别于小白鼠皮下注射、口服,将致死量蛇毒皮下注射后的小白鼠立即于局部注射乙醇,观察蛇毒毒性情况。结果小白鼠经皮下注射致死量眼镜蛇毒后,在局部注射50％（或异蛇米酒）、75％乙醇0．1～0．2ml有一定的保护作用;口服100倍皮下注射致死量眼镜蛇毒未发现有毒性表现,口服经50％乙醇处理后的眼镜蛇毒（100倍皮下注射致死量）未增加小鼠死亡率。结论眼镜蛇毒体外经过乙醇处理后毒性有所下降。口服少量的眼镜蛇毒是安全的。眼镜蛇毒与乙醇混合后口服未见蛇毒毒性增加。     

The effect of simultaneous oral application of ethanol and styrene. [1. Acute and subacute experiments on rats]

Within the lethal dose range, 8.70 mmol/ml ethanol (EtOH, LD50 = 226 mmol/kg) and 6.86 mmol/ml styrene (ST, LD50 = 77.4 mmol/kg) had an additive effect in rats. A four-week pretreatment with 1/10 of the LD50 of the corresponding combination partner did not modify the lethal dose effect of the subsequently administered substance (EtOH or ST). Subchronical treatment with EtOH and ST had an additive effect, too but produced no cumulative effect in relation to lethality. Unlike EtOH, subchronical treatment with ST caused severe symptoms of illness, decrease in body weight and liver lesions. Histological examination at the combined application of EtOH plus ST showed no evidence of qualitatively or intensified effects. Subchronic administration of 1/10 of the LD50-ies of EtOH and ST produced in rats more pronounced histological liver changes than single application of the corresponding LD16-ies. Except for ATP'ase activity, histochemical reactions following EtOH or ST application showed minimal quantitative differences.     

Isolation, characterization and pathology of the toxin from a Microcystis aeruginosa (= Anacystis cyanea) bloom.

The nature of the toxicity of a bloom of blue-green alga, M. aeruginosa (= Anacystis cyanea), that occurred in a man-made lake was investigated. Crude algal bloom extracts were toxic to laboratory mice when injected intraperitoneally. The lethal dose (LD100) of these extracts was 15-30 mg of lyophilized algal bloom per kilogram body weight. The toxin was purified by a procedure that included ammonium sulphate fractionation, solvent extraction, acid precipitation, Sephadex G25 and DEAE-Sephadex chromatography, and high-voltage electrophoresis at pH 6.5. The preparation gave a single spot on high-voltage electrophoresis at pH 9.0, had no free amino group, and was characterized by a simple amino acid composition of equimolar quantities of L-methionine, L-tyrosine, D-alanine, D-glutamic acid, erythro beta-methyl aspartic acid and methylamine. The LD50 for the purified toxin was estimated to be 0.056 mg/kg of mice, and the approximate LD100 is 0.070 mg/kg, based on the total material found from amino acid analysis. Parenteral administration of the purified toxin to mice produced extensive liver lobular haemorrhage and death within 1-3 h. Repeated inoculation of sublethal doses daily over some weeks produced progressive hepatocyte degeneration and necrosis and the development of fine hepatic fibrosis.     

原矛头蝮蛇毒毒性及恢复规律

目的:对原矛头蝮(P.mucrosquamatus)的毒性及其恢复规律进行考察,增进对该蛇毒性的认识。方法:用该蛇连续攻击小鼠,用梯度剂量蛇毒对小鼠进行腹腔注射,统计死亡率,以折算绝对毒性和半数致死量。对毒性耗竭个体,在梯度时间间隔采集蛇毒,以考察毒性恢复规律。结果:原矛头蝮在2 h内可导致6只小鼠死亡。蛇毒对小鼠的半数致死量为12.204μL/Kg。毒性耗竭后,在间隔21天所获得蛇毒的容积达到最大值即190μL,湿重为149.7 mg。结论:毒蛇在攻击猎物时,并不一次性排完毒腺中的所有毒液,随着攻击次数的增多,毒腺中毒液量逐步减少直至耗竭。其毒液量的恢复需要约3周时间,期间,单次排毒量逐渐增加,干物质的含量也基本呈递增趋势。就单次最大排毒量而言,原矛头蝮高于竹叶青、蝮蛇和银环蛇。其单位剂量毒性高于五步蛇和竹叶青。     

沙蜇(Stomolophus meleagris)刺丝囊毒素生物活性的初步分析

从沙蜇触手提取刺丝囊细胞毒素,并对该毒素进行溶血活性、致死活性、SOD活性和抗肿瘤活性的研究。结果显示,沙蜇毒素具有明显的溶血活性,其半溶血率(HU50)约为10.5μg/ml;该毒素还对草鱼显示出较强的致死活性,半致死量(LD50)为50μg毒素/g鱼;同时该毒素具有明显的SOD活性和抗肿瘤活性,当毒素浓度为18μg/ml时其总SOD活性为161 U/mg,而毒素浓度为1 mg/ml时,该毒素对肝癌细胞Bel-7402表现出显著的抑制效果,其抑制率达到54.9%。因此,有必要对沙蜇毒素内的生物活性组分进行深入研究,为沙蜇毒素的开发利用提供依据。     

Cobra venom contains a pool of cysteine-rich secretory proteins

A large family of cysteine-rich secretory proteins (CRISPs) includes proteins of different origin, the function of the majority of CRISPs being unknown. For CRISPs isolated from snake venom, two types of activities were found: two proteins blocked cyclic nucleotide-gated ion channels, several others blocked potassium-stimulated smooth muscle contraction. Thus, snake CRISPs represent potentially valuable tools for studies of ion channels, which makes promising a search for new CRISPs. Here we report on the isolation of several novel CRISPs from the venoms of Asian cobra Naja kaouthia and African cobra Naja haje using a combination of different types of liquid chromatography. Four CRISP variants were identified in N. kaouthia venom and three proteins, one of them acidic, were found in N. haje venom. Acidic CRISP was found in a reptilian venom for the first time. Our data suggest that each cobra venom contains a pool of different CRISPs.     

Acute toxicity of bisphenol A in rats

Bisphenol A (BPA), an estrogenic compound, is used in manufacturing plastics and is known to produce toxic effects on various systems in man and animals. Since the use of plastics in day-to-day life is increasing, exposure to BPA will also increase. Therefore, this study was undertaken to determine the median lethal dose (LD50) of BPA via intraperitoneal and intravenous route in adult rats (by Dixon's up and down method) and also to know the acute systemic changes (in blood pressure, respiration and ECG) produced by lethal dose of BPA. Adult female albino rats of Charles Foster strain were used in the study. LD50 of BPA was 841 and 35.26 mg/kg body weight for ip and iv route, respectively. Injection of lethal dose of BPA (40 mg/kg body weight) produced acute toxicity manifesting as immediate respiratory arrest and hypotension after the injection of BPA followed by bradycardia. The animals died within 7.3 +/- 0.7 min. Volume of ethanol (vehicle; 0.1 mL) present in the lethal dose of BPA was not lethal and had no effect on respiration, blood pressure and heart rate. The results provide evidence that the acute exposure to BPA produces lethality with a very narrow range of lethal and survival dose for iv route. Further, the lethality appears to be due to respiratory arrest and hypotension.     

Isolation and characterization of an acidic lethal phospholipase Az from Malayan cobra (Naja naja sputatrix) venom

An acidic, lethal phospholipase Az was purified to electrophoretic homogeneity from the venom of the Malayan cobra (Naja naja sputatrix). The enzyme has an isoelectric point of 5.58, a molecular weight of 12000, and a medium lethal dose (LD50) of 0.86 micrograms/g in mice by intravenous injection. The enzyme also exhibited weak anticoagulant and edema-forming activities. The amino acid composition of the enzyme is similar to those of other cobra venom phospholipases Az.     

Comparison of the biodistribution of free or liposome-entrapped Crotalus durissus terrificus (South American rattlesnake) venom in mice

The local absorption rate, clearance and tissue distribution of Crotalus durissus terrificus venom, (Cdt) were examined using a two-antibody sandwich ELISA assay. We compared the biodistribution of both free or encapsulated Cdt in mice. Following subcutaneous injection of 10 microg/mouse of free Cdt (0.8 LD50), venom was detected in serum after 15 min, showed its highest level at 30 min (45+/-5 ng/ml) and was cleared from the circulation after 6 h. After 2 h of inoculation, venom was detected in the kidney (57+/-9 ng/g of tissue), spleen (18+/-4 ng/g of tissue) and brain (14+/-6 ng/g of tissue). For both subcutaneous or intravenous injection of free Cdt, venom was firstly detected in the kidney. No Cdt appeared either in the kidney, spleen, brain, or other tissues after subcutaneous inoculation of encapsulated venom even though a higher dose was used, 25 microg/mouse (2 LD50). Venom remained at the site of injection for a period of 1 week. Following intravenous injection of encapsulated venom (5 microg/mouse, 2 LD50), venom was detected in liver and spleen tissues. The biodistribution of encapsulated venom is discussed in relation to the effects of reduction of toxicity and increase of adjuvanticity.     

Modification of the toxicity of Bothrops atrox poison by interventions in the coagulation and kallikrein system of prey

LD50-determinations with venom mixtures from different age groups of Bothrops atrox were carried out on differently pretreated mice. No differences were seen in the LD50 when comparing untreated mice with mice previously defibrinogenated with batroxobin. Inhibition of the coagulation-, kallikrein-kinin- and fibrinolytic system by pretreatment with batroxobin and aprotinin led to a significantly decreased toxicity of the venom mixtures of all age groups. The age-related difference in toxicity had practically disappeared. Furthermore, the number of mice of the latter group dying within one hour after the venom injection was strongly reduced as compared to untreated and only batroxobin-treated animals. Tests performed on rats showed that the rapidly occurring lethality following the venom injection as a consequence of circulatory disturbances (strong fall of arterial blood pressure, bradycardia, dyspnea), may be prevented almost completely by preincubation of the venom with aprotinin.     

Toxicological and immunological aspects of scorpion venom (Tytius pachyurus): neutralizing capacity of antivenoms produced in Latin America

The toxicity and immunochemical properties of Tityus pachyurus Pocock scorpion venom was characterized, as well as the neutralization capacity against it by three anti-scorpion antivenoms (Alacramyn, Instituto Bioclón, México; Suero antiescorpiónico, Instituto Butantán, Sao Paulo, Brasil; and Suero antiescorpiónico, Centro de Biotecnología, Universidad Central de Venezuela, Caracas, Venezuela). The venom yield, obtained by manual milking, 680+/-20 microg venom, a 50% lethal dose in mice was 4.8 microg/kg (90 microg for an 18-20 g mouse). The most common symptoms of venom poisoning in mice were sialorrhea, respiratory distress, profuse sweating, ataxia, behavior alterations (restlessness, somnolence) and hyperglycemia at 3 and 24 hours after subcutaneous venom injection (0.5 LD50). The neutralizing capacity of Bioclón (México City) and Butantán (Sao Paulo) antivenoms (for a 50% effective dose) was 330 and 292 microg venom/ml antivenom, respectively. The Biotecnología (Caracas) antivenom did not neutralize the lethal effect of venom. By electrophoresis (SDS-PAGE) was demonstrated that the venom contains proteins from less than 14 kd to 97 kd. The Western blots indicated immunological reactivity of the three antivenoms with most of venom components, including proteins of low molecular mass (<14 kd). The results allow to conclude that T. pachyurus venom is neutralized efficiently by anti-scorpion antivenoms produced in México and Brasil.     

The biological properties of venoms from juvenile and adult taipan (Oxyuranus scutellatus) snakes.

1. The biological properties of four venom pooled samples from adult taipan (Oxyuranus scutellatus) snakes and one pooled venom sample from six juvenile taipan snakes (11 months old) were compared. 2. The intravenous LD50 (median lethal dose), procoagulant activity and enzymatic activities of the juvenile venom were not significantly different from those of the adult venoms. 3. The juvenile and adult venoms exhibited similar polyacrylamide gel electrophoretic (PAGE) and SDS-PAGE patterns, indicating that they possessed a similar protein composition. 4. The results suggest that there is no significant age-dependency in the biological properties of taipan venom.     

Histopathology, histochemistry and acetylcholinesterase activity after repetitive administration of fluostigmine to albino rat

Histopathological, histochemical and biochemical investigations were performed on the brain, sciatic nerve, skeletal muscle, heart, liver and kidney of rats which were given 5% of LD50 dose of DFP for 10 days. A decrease in AChE activity, degeneration of neurons and necrotic changes in the nuclei of hypothalamus, degeneration of myelin sheaths in sciatic nerve, a decrease in succinic dehydrogenase activity in the myocardium, and a minimal decrease of acid phosphatase activity (AcPh) in the liver were found. The biochemical determination of AChE level indicated about 30% AChE activity in erythrocytes and tibialis muscle, and 40% in the brain 1 hr after the last dose of the inhibitor and 80% and 50% respectively on the 7th day after poisoning in relation to normal values.     

Antagonism of acute cocaine toxicity by buprenorphine.

The effect of buprenorphine pretreatment on the acute cocaine toxicity was assessed in male Swiss Webster mice. Buprenorphine pretreatment (0.15 or 0.30 mg/kg ip, 30 mins before) significantly attenuated the lethal effects of cocaine (60-140 mg/kg ip). The dose of cocaine which resulted in 50% mortality (LD50) in saline pretreated group was 100.61 mg/kg while the LD50 of cocaine in buprenorphine (0.15 and 0.3 mg/kg) pretreated groups were 113.57 and 118.16 mg/kg respectively. There was no significant change in the ratio of brain/plasma levels of cocaine in buprenorphine pretreated group when compared to the ratio from saline treated controls. Furthermore, neither naloxone (10 mg/kg ip, 15 mins before) nor naltrexone (3 mg/kg ip, 15 mins before) pretreatment affected the LD50 of cocaine. When tested 0.5, 1, 2, 4, 8 and 24 hrs after cocaine administration, sublethal dose of cocaine (80 mg/kg ip) injection resulted in significant increase in the plasma lactate dehydrogenase (LDH) levels. Buprenorphine pretreatment significantly attenuated cocaine-induced release of LDH. These results suggest that buprenorphine could be of potential advantage over naloxone in the management of cocaine and heroin ("speed ball") toxicity and in studies on the pharmacotherapy of cocaine-induced toxicity, LDH levels may be used as a biochemical marker to assess the protective effects of drugs.     

Effects of some pesticides on the vital organs of juvenile rainbow trout (Oncorhynchus mykiss)

Gill, trunk kidney, spleen, and liver of rainbow trout (Oncorhynchus mykiss) were examined after exposure to different sublethal concentrations of carbosulfan (25, 50 and 200 μg L⁻¹), propineb (3, 6 and 24 mg L⁻¹), and benomyl (2, 5 and 20 mg L⁻¹) for 14 days. Lesions were observed in gill, trunk kidney, spleen, and liver of rainbow trout exposed to either concentration of pesticides. The most important lesions were determined in the highest concentrations of pesticides. Lamellar fusion, lamellar hyperplasia, epithelial lifting, vacuolization of epithelial tissue, epithelial necrosis, hypertrophy and sloughing of epithelium were observed on fish exposed to carbosulfan, propineb and benomyl. Fish had cell necrosis, degeneration and oedemas in liver, trunk kidney and spleen. None of these lesions were seen in control fish.     

Purification and partial characterization of stonustoxin (lethal factor) from Synanceja horrida venom.

1. The lethal factor of the stonefish (Synanceja horrida) venom, designated as the stonustoxin, was purified to homogeneity by a two-step procedure on Sephacryl S-200 High Resolution (HR) gel permeation and DEAE Bio-Gel A anion exchange chromatography. 2. Stonustoxin has a native mol. wt of 148,000 and an isoelectric point of 6.9. 3. SDS-polyacrylamide gel electrophoresis revealed two subunits (designated alpha and beta) with mol. wts of 71,000 and 79,000, respectively. 4. The amino acid composition of both subunits and the N-terminal amino acid sequence of the beta subunit were also determined. 5. Purified stonustoxin had an LD50 of 0.017 microgram/g which is 22-fold more potent than that of the crude venom. 6. The toxin exhibited potent haemolytic activity in vitro and edema-inducing activity with a minimum edema dose (MED) of 0.15 micrograms in mouse paw. The edema effect was not antagonized by diphenhydramine.     

The effect of decomplementation on the infectious course of Sendai virus in mice

The course of intranasal infection of Sendai virus in CBA and DBA mice was investigated in animals decomplemented with purified cobra venom factor. The mice were decomplemented either immediately before inoculation or at 4 days postinfection. Depletion of complement after the infection had been established had no apparent effect on the course of the viral infection in the two strains of mice. In contrast, both strains of mice were protected completely from the lethal effects of an infectious dose of 1 LD50 of virus when the serum C3 levels were depressed by more than 80% during the early stages of infection. The symptoms of morbidity were less pronounced in these animals and there was a delay in the production of hemagglutination-inhibiting antibody. There was no apparent effect on the growth of the virus in lung tissue. The results suggest that the complement system plays a significant pathogenic role during the course of Sendai virus infections in CBA and DBA mice.     

Relationship between Cancer Slope Factor and Acute Toxicity in Rats and Fish

The purpose of this study was to examine bivariate relationships among cancer slope factor (CSF) and acute toxicity in rats and salmonid fish. Chemicals (n=43) were selected based on the availability of both oral CSF and acute toxicity data (rat oral median lethal dose [LD50] or salmonid median lethal concentration [LC50]). Rat oral LD50, salmonid LC50, and oral CSF data were log-transformed, and a Bonferroni-adjusted alpha level was set at 0.05 for subsequent correlation analysis. A significant correlation was observed between CSF and rat oral LD50 (r=?0.61) but not for CSF and salmonid LC50 (r=?0.29). Moreover, rat and fish acute toxicity were not significantly correlated (r=0.38). The significant correlation between CSF and rat oral LD50 compares favorably with published results reported in related studies. Accordingly, these results support prediction of carcinogenic potency, expressed as oral CSF, based in part on acute toxicity in rats.