253 resultados para Serpente peçonhenta - Veneno


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Mode of access: Internet.

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Tome 5 has title: Supplément au Dictionnaire de physique.

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In Brazil, there is a high incidence of venomous animals. Among them, scorpions are highlighted by their medical importance, and for being their venom a source of several molecules with biological and pharmacological activity not yet fully understood, including several bioactive peptides. Antimicrobial peptides (AMPs) are components of the immune system in prokaryotes and eukaryotes, used in the first line of defense against microorganisms. In the present study, we characterized the first PAM previously identified through transcriptome of the venom gland of the scorpion Tityus stigmurus, named Stigmurin. The characteristics of Stigmurin were investigated by computational modeling and construction of dendrogram. In vitro tests investigated the antibacterial, antifungal, haemolytic and cytotoxic effects of crude venom and Stigmurin. In addition, the structural characteristics of Stigmurin were investigated by circular dochroism in water, 2, 2 , 2- trifluoethanol (TFE) and sodium dodecyl sulfate (SDS) and the models were refined by molecular dynamics simulations. The results showed that the selected sequence encodes a mature protein of 17 amino acid residues and the dendrogram reveals a case of convergent evolution. The crude venom showed no antimicrobial activity, however, Stigmurin exhibited a broad spectrum of antibacterial activity, with minimal inhibitory concentrations (MIC) ranging from 31.25 and 250 µg/mL for different strains, while the hemolytic activity at these concentrations was low. In cytotoxicity studies, the crude venom was unable to reduce cell viability in VERO E6 cells; in contrast, its activity in SiHa cells was significantly higher, corresponding to IC50 of 3.6 µg/mL. For Stigmurin the concentration sable to decrease cell viability of Vero E6 and SiHa cells in 50% were 275.67 µg/mL and 212.54 µg/mL, respectively. The dichroism spectra revealed the conformational flexibility, with predominating extended and β–sheet structures, as well as a remark able renaturation ability. The results suggest that Stigmurin could be considered as a potential antiinfective drug

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Reported accidents involving the poisoning scorpions are still frequent in Brazil, mainly caused by Tityus serrulatus, known as yellow scorpion. Although antivenom sera are produced routinely by various government laboratories, the effectiveness of its use depends on how quickly treatment is initiated and efficiency in the production of antibodies by the immunized animals. In this study, the development of cationic polymeric nanoparticles of poly(lactic acid) aimed to create a modified delivery system for peptides and proteins of T. serrulatus venom, able to enhance the production of serum antibodies against the scorpion toxins. The cationic nanoparticles were obtained by a low energy nanoprecipitation, after study of the parameters’ variations effects over the physicochemical properties of the particles. The surface functionalization of the nanoparticles with the hyperbranched polyethyleneimine was proved by zeta potential analysis and enabled the adsorption by electrostatic interaction of different types of proteins. The protein loading efficiency of 40-80 % to bovine serum albumin (BSA) and 100 % to scorpion venom peptides evaluated by spectrophotometry and polyacrylamide gel electrophoresis confirmed the success of the selected parameters established for obtainment of nanoparticles, produced with size between 100 to 250 nm. The atomic force microscopy analysis and in vitro release showed that the spherical nanoparticles provided a sustained release profile of proteins by diffusion mechanism, demonstrating the potential for application of the nanoparticles in vivo.

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Reported accidents involving the poisoning scorpions are still frequent in Brazil, mainly caused by Tityus serrulatus, known as yellow scorpion. Although antivenom sera are produced routinely by various government laboratories, the effectiveness of its use depends on how quickly treatment is initiated and efficiency in the production of antibodies by the immunized animals. In this study, the development of cationic polymeric nanoparticles of poly(lactic acid) aimed to create a modified delivery system for peptides and proteins of T. serrulatus venom, able to enhance the production of serum antibodies against the scorpion toxins. The cationic nanoparticles were obtained by a low energy nanoprecipitation, after study of the parameters’ variations effects over the physicochemical properties of the particles. The surface functionalization of the nanoparticles with the hyperbranched polyethyleneimine was proved by zeta potential analysis and enabled the adsorption by electrostatic interaction of different types of proteins. The protein loading efficiency of 40-80 % to bovine serum albumin (BSA) and 100 % to scorpion venom peptides evaluated by spectrophotometry and polyacrylamide gel electrophoresis confirmed the success of the selected parameters established for obtainment of nanoparticles, produced with size between 100 to 250 nm. The atomic force microscopy analysis and in vitro release showed that the spherical nanoparticles provided a sustained release profile of proteins by diffusion mechanism, demonstrating the potential for application of the nanoparticles in vivo.

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In our work, we analyze some works of Bartolomeu Campos de Queirós that compose the “autobiographical cycle”, especially those ones that bring the image of father’s absence/presence, the relationship between life and writing, as well as the father’s figurations and his intermediates and substitutes. We especially investigated the aspect of repetition about how the family relations are articulated, highlighting those ones that happen between father and son and that appear in these texts. This problematic interested us as a research object, a priori, because the works of Bartholomeu Campos de Queirós are an exponent of literature for children field, as far as they show that the childhood is not always “colorful”, happy and perfect as several productions supposedly made “for children” seek to have us believe. In addition, the selected texts that have an autobiographical characteristic and put the issue of child suffering because of the father’s absence are configured as a very rich corpus for studies related to the relation between life/work and investigations in the dialogue between Literature and Psychoanalysis. These aspects will permit us to understand why the pain of missing father be repetitive and insistent in these books. Thus, we problematize, by the selected works for this study, the concept of literature for children and young people and the notion of literary reading. We also analyzed in the “statements” given by the author the relationship between life and writing and we investigated, based on psychoanalytic studies, the literary writing as a possibility of both unconscious development of memory marked by the father’s absence – remedy – as of a perpetuation of this same conflict – poison. Furthermore, we analyzed how the relationship between son and father are processed considering the mother’s absence, since the works that have this person’s presence, she seems to mediate such relationships in a certain way.

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El estudio de las combinaciones léxicas según su grado de fijación y su distinción en combinaciones libres, colocaciones y locuciones ha sido realizado desde la perspectiva sincrónica. Planteamos la posibilidad de aplicar las pautas para distinguir estos tipos de estructuras en materiales de tipo diacrónico. Concretamente, nos basamos en los documentos que componen el Corpus del Español del Reino de Granada (CORDEREGRA) para valorar los materiales de este corpus histórico-lingüístico y comprobar si los criterios sincrónicos se pueden aplicar al estudio de documentos de otros siglos.

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Este trabajo tiene como objetivo estudiar los diferentes estados mentales de los personajes de las novelas de Tu rostro mañana, de Javier Marías. Estudiando las reflexiones del narrador sobre J. Deza, Peter Wheeler o Francisco Rico observamos que su decadencia mental se muestra a través de una suerte de ―presciencia‖ o lucidez momentánea que puede servir para mostrar el silencio como única tendencia de todo discurso. Desde el momento en que toda historia de ficción se cimenta sobre un discurso –no importa su cauce de presentación, ni su fuente– este es falsificado por el tiempo, la gente y cualquier otra herramienta que pueda ser utilizada para contar nada. Las conclusiones de este trabajo muestran la quimera que implica tratar de mantener una contención absoluta sobre lo acaecido, pues dicho vacío de narrativas será ocupado por una suplantación que suele ser el reverso más infame de sus actores. Es por ello que el narrador J. Deza sigue conminado a explicar sus historias, incluso allí donde uno diría que ya no puede haber ni palabras suficientes para traducir un hecho en ficción.

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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.

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In Brazil, accidents with scorpions are considered of medical importance, not only by the high incidence, but also for the potentiality of the venom from some species in determining severe clinical conditions. Tityus stigmurus is a widely distributed scorpion species in Northeastern Brazil and known to cause severe human envenomations, inducing pain, hyposthesia, edema, erythema, paresthesia, headaches and vomiting. The present study uses a transcriptomic approach to characterize the molecular repertoire from the non-stimulated venom gland of Tityus stigmurus scorpion. A cDNA library was constructed and 540 clones were sequenced and grouped into 37 clusters, with more than one EST (expressed sequence tag) and 116 singlets. Forty-one percent of ESTs belong to recognized toxin-coding sequences, with antimicrobial toxins (AMP-like) the most abundant transcripts, followed by alfa KTx- like, beta KTx-like, beta NaTx-like and alfa NaTx-like. Our analysis indicated that 34% include other possible venom molecules , whose transcripts correspond to anionic peptides, hypothetical secreted peptides, metalloproteinases, cystein-rich peptides and lectins. Fifteen percent of ESTs are similar to cellular transcripts. Sequences without good matches corresponded to 11%. This investigation provides the first global view of cDNAs from Tityus stigmurus. This approach enables characterization of a large number of venom gland component molecules, which belong either to known or atypical types of venom peptides and proteins from the Buthidae family