负压封闭引流治疗大面积犬咬伤疗效观察

目的：观察负压封闭引流治疗大面积犬咬伤疗效及副作用。方法：对3例大面积犬咬伤患者采用负压封闭引流技术,观察其治疗效果及随访后的不良反应发生情况。结果：3例患者中,2例术后7 d一期缝合创面,1例术后10 d缝合创面。3例全部获得随访,1例最长6个月随访,患者创面皮肤愈合良好,皮色、皮温、皮肤弹性及肢体功能均正常,无并发其他异常反应。3例缝合前创面细菌培养未见细菌生长。结论：负压封闭引流治疗创面肉芽新鲜,治疗、护理简单,创面无再次污染及感染的发生,对大面积犬咬伤是一项安全有效的治疗技术。     

优选精制蛇毒酶凝胶剂基质组成及制备工艺

目的室温条件下优选精制蛇毒酶凝胶剂基质组成及制备工艺。方法以凝胶剂的稳定性及外观性状为考察指标,以卡波姆-940、氮酮、丙三醇-丙二醇和吐温-80为可变因素,选用L9(34)表进行正交实验。结果最优的基质组成是:卡波姆-940 2.0g,氮酮1.0g,丙三醇-丙二醇为7g∶3g,吐温-80 1.5g。结论按该法制备的凝胶剂符合中国药典2005年版软膏剂的有关规定。     

Jararhagin, a snake venom metalloproteinase-disintegrin, stimulates epithelial cell migration in an in vitro restitution model

The snake venom metalloproteinase-disintegrin jararhagin (JG) has no chemotactic activity but stimulates the migration of neutrophils in vivo through a mechanism still unclear. In this study we investigated the effects of jararhagin on epithelial cell adhesion and migration in vitro. F-actin arrangement and the distribution of laminin, fibronectin, several integrins and phosphorylated Focal Adhesion Kinase (FAK) were studied using rhodamine–phalloidin and immunofluorescence. Maximum stimulation of migration (about 100%) was obtained with 5 μg/ml JG, with about 38% inhibition of cellular adhesion. In migratory cells the toxin stimulated the formation of filopodia, lamellipodia and stress fibers. The pericellular fibronectin matrix was lost in migrating cells, while laminin was less affected. The toxin stimulated FAK phosphorylation and the recruitment of v-containing integrins to focal contacts, whereas integrins containing the 2 subunit were reduced in these junctions. Inactivation of the toxin with 1,10 phenanthroline showed that the catalytic activity is important for the effect of jararhagin on cell migration, FAK phosphorylation and for the recruitment of v, but not as much for the anti-adhesive effect. In conclusion, jararhagin stimulates the migration of epithelial cells in vitro through a mechanism that involves its proteolytic activity, qualitative changes in cellular adhesion and the formation of actin-rich cellular processes.     

Effect of the metalloproteinase inhibitor batimastat in the systemic toxicity induced by Bothrops asper snake venom: understanding the role of metalloproteinases in envenomation.

The peptidomimetic hydroxamate metalloproteinase inhibitor batimastat (BB-94) was assessed for its ability to neutralize the systemic effects (lethality, hemorrhage and coagulopathy) induced by the venom of Bothrops asper, the most important snake from a medical standpoint in Central America. Batimastat inhibited lethality when a venom challenge dose of two LD(50)s was used by intraperitoneal and intravenous routes, with ED(50)s of 250 and 22 microM, respectively. With a challenge dose of three LD(50)s, lethality was not abrogated, but a conspicuous and dose-dependent delay in the time of death was observed in mice injected with mixtures of venom plus batimastat. Upon incubation with 500 microM batimastat, venom LD(50) increased 2.86-fold (intraperitoneal route) and 2.37-fold (intravenous route), when compared with LD(50) of venom alone. Batimastat also inhibited the hemorrhagic effect induced by venom in the lungs after intravenous injection. Moreover, batimastat exerted a significant inhibition of in vitro coagulant and in vivo defibrinogenating effects of venom, evidencing that metalloproteinases play a key role in the coagulopathy characteristic of B. asper envenomation. The remaining uninhibited coagulant effect is due to serine proteinases, i.e. thrombin-like enzymes, since this effect was completely abrogated by the combination of batimastat and PMSF. Our results stress the view that metalloproteinases play a relevant role in the systemic pathophysiology of B. asper envenomation and that metalloproteinase inhibitors may become a therapeutic alternative in this pathology.     

Clinical consequences of spider bites: recent advances in our understanding.

Spider bite continues to be a controversial subject worldwide and attribution of clinical effects to different spiders is problematic because of poor case definition and paucity of clinical evidence. The effects of medically important spiders are sometimes underestimated and simultaneously there is misattribution of effects to harmless spider groups. The majority of suspected spider bites present as skin lesions or necrotic ulcers where the history of a spider bite must be confirmed. To be a definite spider bite, the patient must immediately observe the spider and there be evidence of the bite, such as pain. Important groups of spiders worldwide include the widow spiders (latrodectism), recluse spiders (loxoscelism) and some mygalomorph spiders including the Australian Funnel web spider. Most spiders only cause minor effects, including a large number of groups that have been implicated in necrotic arachnidism.     

Merit and Demerit of Polyvalent Snake Antivenoms

Polyvalent antivenoms contain specific antibodies capable of neutralizing a number of homologous venoms from different species/genera. They can save lives of victims of snake envenomations, even when the culprit snake has not been identified (the usual case, about 80% of the time), and a monovalent antivenom ca not be chosen. They are useful in areas where there are too many poisonous species to produce monovalent antivenoms against all of them. It is now possible to prepare polyvalent antivenoms with high potencies comparable to those of the corresponding monovalent antivenoms. With good manufacturing processes, these antivenoms have been shown to cause few and minor adverse reactions. In addition, polyvalent antivenoms exhibit a wider range of paraspecific neutralization of venoms from different species/genera, even from distant geographic areas. Lastly, it is less expensive and easier to produce and handle a few polyvalent antivenoms than batteries of monovalent antivenoms.     

Candidatus Coxiella massiliensis Infection

Bacteria genetically related to Coxiella burnetii have been found in ticks. Using molecular techniques, we detected Coxiella-like bacteria, here named Candidatus Coxiella massiliensis, in skin biopsy samples and ticks removed from patients with an eschar. This organism may be a common agent of scalp eschar and neck lymphadenopathy after tick bite.     

Digestive properties of the venom of the Australian Coastal Taipan, Oxyuranus scutellatus (Peters, 1867).

The digestive properties of Australian elapid snake venoms have not been studied to any great extent. To address this, the in vitro digestive properties of Oxyuranus scutellatus (Australian Coastal Taipan) venom were investigated in a simulation of the in vivo conditions using the parameters reported for the stomach of snakes and representative prey for this species. The amount of soluble protein released was measured over time using a bicinchoninic acid (BCA) assay. Dismembered mouse hindlegs were injected intramuscularly with 0.1 ml O. scutellatus venom (concentration 10 mg/ml) and maintained in a micro-anaerobic, acidic environment (pH approximately 1.2-1.7) at 25 degrees C. The bathing liquid was sampled every 24 h for 7 days, and assayed for soluble protein. Statistical analysis revealed that O. scutellatus venom increased the rate at which proteins were released when compared to a negative control suggesting the potential importance of envenomation in the digestion of whole prey.     

Molecular diversity of disintegrin-like domains within metalloproteinase precursors of Bothrops jararaca.

Disintegrins are small peptides isolated from the venom of several snake families which act as integrin-antagonists or agonists, interacting with a variety of biological processes mediated by integrins. In this work we describe five new disintegrin-like domains within metalloproteinase precursor sequences, obtained from a Bothrops jararaca venom gland cDNA library. Among the new disintegrin-like domains, four were contained in PIII metalloproteinase precursors, with three of them presenting ECD-motifs and one presenting a new KCD-motif. Moreover, we found three disintegrin-like domains within PII metalloproteinase precursors. Two of them are similar to the already described disintegrins jarastatin and jararacin. The third molecule is unusual, presenting some typical PIII metalloproteinase characteristics but lacking the cysteine-rich domain being, thus, classified as a PII metalloproteinase. Only few reports presented molecules with these characteristics. Sequence analysis suggests that these molecules are intermediate steps between the more ancient PIII and the more recent PII metalloproteinases. We also investigated disintegrin N-terminus diversity in B. jararaca crude venom by purifying jarastatin and jararacin and analyzing them by mass spectrometry.     

Snake venom glutaminyl cyclase.

Glutaminyl cyclase (QC) catalyzes N-terminal glutamine cyclization of many endocrine peptides and is typically abundant in brain tissue. As three-finger toxins in the venoms of colubrid snakes Boiga dendrophila and Boiga irregularis contain N-terminal pyroglutamate, we searched for QC in venom glands of both snakes. Here we report cDNA sequences of QC from brain and venom gland tissues of Boiga species. We propose that QC expressed in snake venom gland tissue plays a role in the N-terminal pyroglutamate formation of several snake venom toxins, indirectly contributing to venom potency.