128 resultados para Serpente


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Tome 5 has title: Supplément au Dictionnaire de physique.

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Antiophidic activity from decoct of Jatropha gossypiifolia L. leaves against Bothrops jararaca venom. Snakebites are a serious worldwide public health problem. In Latin America, about 90 % of accidents are attributed to snakes from Bothrops genus. Currently, the main available treatment is the antivenom serum therapy, which has some disadvantages such as inability to neutralize local effects, risk of immunological reactions, high cost and difficult access in some regions. In this context, the search for alternative therapies to treat snakebites is relevant. Jatropha gossypiifolia L., a medicinal plant popularly known in Brazil as “pinhão-roxo”, is very used in folk medicine as antiophidic. So, the aim of this study is to evaluate the antiophidic properties of this species against enzymatic and biological activities from Bothrops jararaca snake venom. The aqueous leaf extract of J. gossypiifolia was prepared by decoction. The inhibition studies were performed in vitro, by pre-incubation of a fixed amount of venom with different amounts of extract from J. gossypiifolia for 60 min at 37 °C, and in vivo, through oral or intraperitoneal treatment of animals, in different doses, 60 min before venom injection. The proteolytic activity upon azocasein was efficiently inhibited, indicating inhibitory action upon metalloproteinases (SVMPs) and/or serine proteases (SVSPs). The extract inhibited the fibrinogenolytic activity, which was also confirmed by zymography, where it was possible to observe that the extract preferentially inhibits fibrinogenolytic enzymes of 26 and 28 kDa. The coagulant activity upon fibrinogen and plasma were significantly inhibited, suggesting an inhibitory action upon thrombin-like enzymes (SVTLEs), as well as upon clotting factor activators toxins. The extract prolonged the activated partial thromboplastin time (aPTT), suggesting an inhibitory action toward not only to SVTLEs, but also against endogenous thrombin. The defibrinogenating activity in vivo was efficiently inhibited by the extract on oral route, confirming the previous results. The local hemorrhagic activity was also significantly inhibited by oral route, indicating an inhibitory action upon SVMPs. The phospholipase activity in vitro was not inhibited. Nevertheless, the edematogenic and myotoxic activities were efficiently inhibited, by oral and intraperitoneal route, which may indicate an inhibitory effect of the extract upon Lys49 phospholipase (PLA2) and/ or SVMPs, or also an anti-inflammatory action against endogenous chemical mediators. Regarding the possible action mechanism, was observed that the extract did not presented proteolytic activity, however, presented protein precipitating action. In addition, the extract showed significant antioxidant activity in different models, which could justify, at least partially, the antiophidic activity presented. The metal chelating action presented by extract could be correlated with SVMPs inhibition, once these enzymes are metal-dependent. The phytochemical analysis revealed the presence of sugars, alkaloids, flavonoids, tannins, terpenes and/or steroids and proteins, from which the flavonoids could be pointed as major compounds, based on chromatographic profile obtained by thin layer chromatography (TLC). In conclusion, the results demonstrate that the J. gossypiifolia leaves decoct present potential antiophidic activity, including action upon snakebite local effects, suggesting that this species may be used as a new source of bioactive molecules against bothropic venom.

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Envenomation caused by venomous animals, mainly scorpions and snakes, are a serious matter of public health. Tityus serrulatus is considered the most venomous scorpion in South America because of the high level of toxicity of its venom. It is responsible for causing serious accidents, mainly with kids. The species Bothrops jararaca is a serpent that has in its venom a complex mixture of enzyme, peptides and other molecules. The toxins of the venom of B. jararaca induce local and systemic inflammatory responses. The treatment chosen to serious cases of envenomation is the intravenous administration of the specific antivenom. However, the treatment is not always accessible to those residents in rural areas, so that they use medicinal plant extracts as the treatment. In this context, aqueous extracts, fractions and isolated compounds of Aspidosperma pyrifolium (pereiro) and Ipomoea asarifolia (salsa, salsa-brava), used in popular medicine, were studied in this research to evaluate the anti-inflammatory activity in the peritonitis models induced by carrageenan and peritonitis induced by the venom of the T. serrulatus (VTs), and in the local oedema model and inflammatory infiltrate induced by the venom of the B. jararaca, administrated intravenously. The results of the assays of cytotoxicity, using the MTT, showed that the aqueous extracts from the plant species presented low toxicity to the cells that came from the fibroblast of the mouse embryo (3T3).The chemical analysis of the extracts by High Performance Liquid Chromatography revealed the presence of the rutin flavonoid, in A. pyrifoliu, and rutin, clorogenic acid and caffeic acid, in I. asarifolia. Concerning the pharmacological evaluation, the results showed that the pre-treatment using aqueous extracts and fractions reduced the total leukocyte migration to the abdominal cavity in the peritonitis model caused by the carrageenan and in the peritonitis model induced by the T. serulatus venom. Yet, these groups presented anti-oedematous activity, in the local oedema model caused by the venom of the B. jararaca, and reduced the inflammatory infiltrate to the muscle. The serum (anti-arachnid and anti-bothropic) specific to each venom acted inhibiting the inflammatory action of the venoms and were used as control. The compounds identified in the extracts were also tested and, similar to the plant extracts, showed meaningful anti-inflammatory effects, in the tested doses. Thus, these results are indicating the potential anti-inflammatory activity of the plants studied. This is the first research that evaluated the possible biological effects of the A. pyrifolium and I. asarifolia, showing the biological potential that these species have.

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CHAPTER II: Snake venoms are a complex mixture of organic and inorganic compounds, proteins and peptides such as aminotransferases, acetylcholinesterase, hyaluronidases, L-amino acid oxidase, phospholipase A2, metalloproteases, serine proteases, lectins, disintegrins, and others. Phospholipase A2 directly or indirectly influence the pathophysiological effect on envenomation, as well as their participation in the digestion of the prey. They have several other activities such as hemolytic indirect action, cardiotoxicity, aggregating of platelets, anticoagulant, edema, myotoxic and inflammatory activities. In this work, we describe the functional characterization of BaltMTx, a PLA2 from Bothrops alternatus that inhibits platelet aggregation and present bactericidal effect. The purification of BaltMTx was carried out through three chromatographic steps (ion-exchange on a DEAE-Sephacel column, followed by hydrophobic chromatography on Phenyl–Sepharose and affinity chromatography on HiTrap™ Heparin HP). The protein was purified to homogeneity as judged by its migration profile in SDS–PAGE stained with coomassie blue, and showed a molecular mass of about 15 kDa under reducing conditions and approximately 25 kDa in non-reducing conditions. BaltMTx showed a rather specific inhibitory effect on platelet aggregation induced by epinephrine in human platelet-rich plasma in a dose-dependent manner, whereas it had little or no effect on platelet aggregation induced by collagen or adenosine diphosphate. BaltMTx also showed antibacterial activity against Staphylococcus aureus and Escherichia coli. High concentrations of BatlMTx stimulated the proliferation of Leishmania (Leishmania) infantum and Leishmania (Viania) braziliensis. BaltMTx induced production of inflammatory mediators such as IL-10, IL-12, TNF-α and NO. BaltMTx could be of medical interest as a new tool for the development of novel therapeutic agents for the prevention and treatment of thrombotic disorders as well as bactericidal agent.

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I serpenti robot sono una classe di meccanismi iper-ridondanti che appartiene alla robotica modulare. Grazie alla loro forma snella ed allungata e all'alto grado di ridondanza possono muoversi in ambienti complessi con elevata agilità. L'abilità di spostarsi, manipolare e adattarsi efficientemente ad una grande varietà di terreni li rende ideali per diverse applicazioni, come ad esempio attività di ricerca e soccorso, ispezione o ricognizione. I robot serpenti si muovono nello spazio modificando la propria forma, senza necessità di ulteriori dispositivi quali ruote od arti. Tali deformazioni, che consistono in movimenti ondulatori ciclici che generano uno spostamento dell'intero meccanismo, vengono definiti andature. La maggior parte di esse sono ispirate al mondo naturale, come lo strisciamento, il movimento laterale o il movimento a concertina, mentre altre sono create per applicazioni specifiche, come il rotolamento o l'arrampicamento. Un serpente robot con molti gradi di libertà deve essere capace di coordinare i propri giunti e reagire ad ostacoli in tempo reale per riuscire a muoversi efficacemente in ambienti complessi o non strutturati. Inoltre, aumentare la semplicità e ridurre il numero di controllori necessari alla locomozione alleggerise una struttura di controllo che potrebbe richiedere complessità per ulteriori attività specifiche. L'obiettivo di questa tesi è ottenere un comportamento autonomo cedevole che si adatti alla conformazione dell'ambiente in cui il robot si sta spostando, accrescendo le capacità di locomozione del serpente robot. Sfruttando la cedevolezza intrinseca del serpente robot utilizzato in questo lavoro, il SEA Snake, e utilizzando un controllo che combina cedevolezza attiva ad una struttura di coordinazione che ammette una decentralizzazione variabile del robot, si dimostra come tre andature possano essere modificate per ottenere una locomozione efficiente in ambienti complessi non noti a priori o non modellabili.

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O estudo teve como objetivo descrever a biologia reprodutiva e a dieta de populações de Thamnodynastes hypoconia em ambientes úmidos subtemperados do extremo sul brasileiro. Para avaliação da reprodução foram feitas análises macroscópicas das gônadas. Para avaliação da ecologia alimentar foram empregadas análises de conteúdo estomacal e de isótopos estáveis (δ13C e δ15N). Os machos apresentaram maior comprimento rostro-cloacal que as fêmeas e atingiram a maturidade sexual com menor tamanho corporal. O ciclo reprodutivo das fêmeas foi sazonal, com vitelogênese secundária ocorrendo entre o inverno e a primavera. Os machos apresentaram ciclo contínuo. Aparentemente a cópula ocorre entre o final da primavera e o início do verão, quando foram detectados embriões nas fêmeas e a parturição ocorreu no verão. Não houve relação entre o tamanho da ninhada e o tamanho da fêmea, e a frequência reprodutiva de 40% foi considerada relativamente baixa. Todavia, por ser uma espécie dominante em banhados subtemperados do extremo sul do Brasil sua estratégia reprodutiva parece ser eficiente. Dessa forma, o ciclo contínuo dos machos, bem como a viviparidade possam potencializar o deslocamento do pico reprodutivo da população de modo a ajustar-se de acordo com os picos de temperatura do ambiente. A análise de conteúdo estomacal mostrou uma dieta predominantemente anurófaga, exceto por um único lagarto. Hylidae foi a família mais representativa, com predomínio de Hypsiboas pulchellus, seguida de Leptodactylidae, onde Leptodactylus latrans teve maior importância. As análises de isótopos estáveis corroboraram a importância dessas espécies na alimentação da serpente. Apesar de ser uma serpente terrestre, T. hypoconia apresentou assinatura isotópica mais próxima das fontes primárias oriundas do ambiente aquático, o que indica a importância das áreas alagáveis para a subsistência de organismos terrestres de habitats adjacentes.