东亚钳蝎毒素对大鼠实验性大肠癌的抑制研究

利用盐酸二甲肼(DMH)诱发Wistar鼠大肠癌的动物模型,通过分组、分阶段研究蝎毒素对大肠肿瘤发生过程和组织病理改变的作用。结果发现蝎毒素可以减少诱癌的鼠死亡率和诱癌率。20周内单纯诱癌组死亡率达32.69％,蝎毒灌胃组和腹腔注射组分别为23.08％和20.51％,其中蝎毒注射组死亡率与单纯诱癌组相比有显著差异(P<0.05)。20-31周单纯诱癌组诱癌率为81.82％,蝎毒注射组为44％,两组差异显著(P<0.01)。大肠癌核仁组成区染色结果发现单纯诱癌AgNOR颗粒明显增加而蝎毒注射组显著减少,每核AgNOR颗粒数两组有显著差异(P<0.05),研究提示蝎毒素具有去除DMH毒性,降低实验肿瘤的发生,抑制大肠肿瘤细胞rRNA活性,直接抑杀肿瘤细胞的作用。     

蝰蛇毒压电免疫传感器固定方法的研究

目的：为研制蝰蛇毒压电免疫传感器，研究抗蛇毒抗体固定于石英晶体银电极表面的固定技术。方法：采用马抗蝰蛇毒血清抗体和抗蝰蛇毒鸡卵黄抗体作为生物敏感材料，对比研究了胱胺自组装-PSS反相吸附法和PEI粘附-戊二醛交联法：比较了采用两种固定方法所制的压电免疫传感器的性能。结果：鸡卵黄抗体采用PEI粘附-戊二醛交联法效果较好，其制备的IgY压电免疫传感器检测蝰蛇毒灵敏度为0．5ug／mL；而马血清抗体用胱胺自组装-PSS反相吸附法较好，其制备的IgG’免疫传感器检测蝰蛇毒灵敏度为10ug／mL。结论：以PEI粘附-戊二醛交联法固定抗蝰蛇毒鸡卵黄抗体所制备的蝰蛇毒压电免疫传感器的性能稳定，特异性好，可实现蛇毒的快速检测。     

Haemodynamic effects of the crude venom from nematocysts of the box-jellyfish Chiropsalmus quadrigatus (Habu-kurage) in anaesthetized rabbits.

Haemodynamic effects of saline-extracted venom from nematocysts isolated from tentacles of the box-jellyfish Chiropsalmus quadrigatus (Habu-kurage) were investigated. In anaesthetized rabbits, i.v. injections of the venom produced hypotension following a transient hypertension. Mean femoral arterial blood flow markedly decreased immediately after the injection and femoral vascular resistance increased. Left ventricular dP/dt remarkably decreased after a transient and small increase, and heart rate decreased. Left ventricular end-diastolic pressure markedly elevated. All of the above changes by 0.2-5 microg/kg of the venom expressed as the amount of protein were seen dose-dependently and occurred without tachyphylaxis. In five of seven animals received an injection of the venom at 10 microg/kg, irreversible cardiac arrest occurred. Changes produced by 1 or 2 microg/kg of the venom were significantly attenuated either by heating the venom at 40 degrees C for 10min or by pretreatment with diltiazem. These results indicate that the venom from Habu-kurage has both vasoconstrictor and cardiodepressive effects, and suggest that these thermolabile actions may be due partly to activation of voltage-dependent calcium channels and probably subsequent calcium-overload.     

Effects of anti-inflammatory drugs on rat hind-paw swelling caused by phospholipase A2 from Naja naja atra venom

Summary Rat hind-paw swelling was induced dose-dependently by subplantar injection of acidic phospholipase A₂ (NNAVPLA₂) from Naja naja atra venom. Diphenhydramine and methysergide pretreatment greatly reduced the swelling effect caused by NNAVPLA₂. Several doses of compound 48/80 given to deplete the histamine content of rat hind paw, also greatly suppressed NNAVPLA₂-induced paw swelling. The paw swelling caused by NNAVPLA₂ was reduced following pretreatment with BW 755C, a dual inhibitor of cyclooxygenase/lipoxygenase, or subplantar co-injection with FPL 55712, a SRS-A antagonist, while pretreatment with acetylsalicylic acid had no effect. Captopril significantly potentiated the NNAVPLA₂-induced paw swelling. The recovered myeloperoxidase activity was increased within 1 h and still elevated in the rat paw 3 to 6 h after subplantar injection of NNAVPLAZ. In isolated peripheral PMN leukocyte suspension, NNAVPLAZ caused a release of superoxide radical. Subplantar co-injection with superoxide dismutase/catalase significantly inhibited NNAVPLA₂-induced paw swelling. NNAVPLA₂ did not trigger platelet aggregation either in platelet-rich plasma or in washed platelet suspension. NNAVPLA₂-induced hind-paw swelling was also suppressed by the pretreatment with isoprenaline or terbutaline, while this response was not affected by co-injection with BN 52021, a PAF antagonist, into the paw. It is concluded that the hindpaw swelling caused by NNAVPLAZ is mainly due to histamine and serotonin released from mast cells and partly due to the formed kinins and SRS-A in the inflammatory area, and superoxide radical from PMN leukocytes. Send offprint requests to C.-M. Teng at the above address     

Identification, cloning and sequencing of two major venom proteins from the box jellyfish, Chironex fleckeri.

Two of the most abundant proteins found in the nematocysts of the box jellyfish Chironex fleckeri have been identified as C. fleckeri toxin-1 (CfTX-1) and toxin-2 (CfTX-2). The molecular masses of CfTX-1 and CfTX-2, as determined by SDS-PAGE, are approximately 43 and 45 kDa, respectively, and both proteins are strongly antigenic to commercially available box jellyfish antivenom and rabbit polyclonal antibodies raised against C. fleckeri nematocyst extracts. The amino acid sequences of mature CfTX-1 and CfTX-2 (436 and 445 residues, respectively) share significant homology with three known proteins: CqTX-A from Chiropsalmus quadrigatus, CrTXs from Carybdea rastoni and CaTX-A from Carybdea alata, all of which are lethal, haemolytic box jellyfish toxins. Multiple sequence alignment of the five jellyfish proteins has identified several short, but highly conserved regions of amino acids that coincide with a predicted transmembrane spanning region, referred to as TSR1, which may be involved in a pore-forming mechanism of action. Furthermore, remote protein homology predictions for CfTX-2 and CaTX-A suggest weak structural similarities to pore-forming insecticidal delta-endotoxins Cry1Aa, Cry3Bb and Cry3A.     

Differentiation between formation,in plasma,of anaphylatoxin and of endogenous pyrogen

Summary Two anaphylatoxin-forming agents have been investigated with respect to possible pyrogenic effects: the AT forming fraction of cobra venom and agar.The cobra venom fraction produced fever in rabbits. The pyrogenic principle is, however, not identical with the AT forming enzyme. Unlike the latter the pyrogenic principle is stable in acidic solution and destroyed by periodate. It may be a lipopolysaccharide.Rabbit plasma, incubated with agar caused fever in rabbits. Agar also induced pyrogenic activity in saline after it had been incubated in that medium. The active principle proved to be agaropectin, the water-soluble acidic fraction of agar. Agarose was inert. In contrast, anaphylatoxin formation is induced by agarose, not by agaropectin.In rabbit plasma, agaropectin induces the formation of an endogenous pyrogen. This principle can be separated from the agaropectin by DEAE cellulose chromatography. It is further distinguished from the latter by being heat-labile.Besides being activated by different agents the processes of pyrogen and AT formation differ in their requirement for cations. AT formation is blocked by EDTA but pyrogen formation is not. It is concluded that in spite of similarities and common activation by endotoxins the processes of AT and pyrogen formation are different and independent events.     

Histological characterization of the special venom secretory cells in the stinger of rays in the northern waters of Persian Gulf and Oman Sea

Rays are common elasmobranches in the northern waters of Persian Gulf and Oman Sea that may have one or more mineralized serrated stingers on the whip-like tail. The stingers are covered by epidermal cells among which some can produce venom. When these animals are dorsally touched, the stinger can be introduced into the aggressor by a whip reflex mechanism of the tail when the pectoral fins are touched, causing severe mechanical injuries and inoculating the venom. The exact localization of the venom secretory cells in the stinger of different species is controversial, but it is known that the cells are preferentially located in the ventro-lateral grooves in marine stingrays. A comparative morphological characterization of the stinger epidermal tissue of different ray species in the northern part of Persian Gulf and Oman Sea was carried out in this study. EDTA was used for decalcification of stings and conventional histological processes were subsequently employed. The results indicated that structure of dermis and epidermis layers of stings in all species are similar to the structure of corresponding layers in other parts of fish's body. The results of the present study have shown that all examined species of Dasyatidae family, but not Myliobatidae and Gymnuridae families, had venom secretory cells. Distribution of venom secretory cells varies in each species and is often located around or inside the stinger ventro-lateral grooves. These differences among the stingers of various species may explain the envenomation severity in these species.     

Species differences in the neuromuscular activity of post-synaptic neurotoxins from two Australian black snakes (Pseudechis porphyriacus and Pseudechis colletti)

Bites by Australian black snakes (Pseudechis spp.) do not cause neurotoxicity in human envenoming. This is unusual as in vitro neurotoxicity has been reported for all Pseudechis spp. venoms. The present study aimed to identify, isolate and characterise neurotoxins from the venoms of Pseudechis porphyriacus and Pseudechis colletti to elucidate the reason for the lack of neurotoxicity in humans. α-Elapitoxin-Ppr1 and α-elapitoxin-Pc1 were isolated from P. porphyriacus and P. colletti, respectively, using reverse-phase high performance liquid chromatography. Each toxin consisted of 62 amino acids with molecular weights of 6746.5 Da and 6759.6 Da, respectively. α-Elapitoxin-Ppr1 and α-elapitoxin-Pc1 caused concentration-dependent (0.1–0.3 μM) inhibition of indirect twitches in the chick biventer cervicis nerve-muscle preparation. Both toxins inhibited contractile responses to exogenous ACh and CCh, but not KCl, suggesting a post-synaptic mode of action at the nicotinic acetylcholine receptor (nAChR). CCh concentration–response curves obtained in the presence or absence of α-elapitoxin-Ppr1 or α-elapitoxin-Pc1 indicated pA₂ values of 6.97 ± 0.03 and 7.04 ± 0.07, respectively. Neither α-elapitoxin-Ppr1 (0.1 μM) nor α-elapitoxin-Pc1 (0.1 μM) had a significant effect on the electrically-induced twitches of the rat isolated phrenic nerve-diaphragm preparation. When the venom with the toxin removed (10 μg/ml) was added to both the rat and chick preparations, the inhibition was significantly less than that caused by the intact whole venoms (10 μg/ml). The current study shows that α-elapitoxin-Ppr1 and α-elapitoxin-Pc1 act as pseudo-irreversible antagonists at the nAChR of the skeletal neuromuscular junction and that the avian preparation is more sensitive to the neurotoxic effects of these toxins than the mammalian preparation.     

BITES AND ENVENOMATIONS BY COLUBRID SNAKES IN MEXICO AND CENTRAL AMERICA

Information on bites by snakes of the family Colubridae in Mexico and Central America is reviewed. Little is known of the biochemistry and pharmacology of the Duvernoy gland secretion (venom) of colubrids from this region, although some reports describe proteolytic, phosphodiesterase, phospholipase A₂ and hemorrhagic activities. A search of published reports and an effort to obtain reliable unpublished information on colubrid snake bites in the region documented cases inflicted by species of the genera Conophis, Coniophanes, Crisantophis, Erythrolamprus, Pliocercus, Oxybelis and Dryadophis (=Mastigodryas). The following general pattern emerges from the analysis of these cases: 1) Bites occurred mainly in hands and fingers on people that frequently manipulate colubrids, i.e. herpetologists, herpetoculturists and people that take care of these snakes at museums, exhibits or zoos; and 2) In most cases, only mild local effects were described, i.e. pain, swelling and, in few cases, ecchymosis. In only one case by Erythrolamprus bizonus there was ecchymosis beyond the bitten region, whereas persistent bleeding at the bite site was reported in a Conophis lineatus case. No systemic alterations were described in any of the cases. Management of colubrid bites in Mexico and Central America includes cleaning and disinfection of the bitten area, together with administration of tetanus toxoid. In the case of local infection, antibiotics are administered. There is no experimental or clinical evidence supporting the use of Crotalinae antivenoms in these bites. Despite the lack of systemic alterations in the cases described, caution should be exercised when manipulating these snakes, and bitten people should be closely observed for the potential development of bleeding and coagulopathies, since these effects have been described in bites by colubrid snakes from other regions of the world.     

中华眼镜蛇毒组分C抗白血病作用的实验研究

目的：研究眼镜蛇毒组分Ｃ对白血病细胞的直接作用及机制。方法：应用ＭＴＴ、ＤＮＡ电泳、流式细胞仪ＲＴ－ＰＣＲ等方法,观察眼镜蛇毒组分Ｃ对ＨＬ６０等９株白血病细胞系的毒性作用、量效关系及白血病细胞经过眼镜蛇毒组分Ｃ处理后的生物化学、Ｂｃｌ－２／Ｂａｘ表达水平变化。结果：眼镜蛇毒组分对９株人白血病细胞系均有明显的抑制作用,ＩＣ５０为０．００４６～４．４０μｇ／ｍｌ,且呈较好的量效关系（ｒ为０．６６～０．