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Agora exibindo 1 - 8 de 8
  • Resumo IPEN-doc 13117
    The lesson from snake venom: ion transport and glycolysis are couple through the pumping rate of the Na/KAT pase
    2007 - LIMA, V.M.F. de; HANKE, W.; CAMILLO, M.A.; SPENCER, P.; NASCIMENTO, N.
  • Artigo IPEN-doc 14476
    Young ovine death during hyperimmunization: crotalic envenomation or copper toxicosis?
    2008 - FERREIRA JUNIOR, R.S.; NASCIMENTO, N.; COUTO, R.; ALVES, J.B.; MEIRA, D.A.; BARRAVIERA, B.
  • Artigo IPEN-doc 11620
    Immune response against irradiated with sup(60)Co gamma-rays
    2006 - BAPTISTA, J.A.; SPENCER, P.J.; OLIVEIRA, J.E.; CESARE, M.S.; NASCIMENTO, N.
  • Artigo IPEN-doc 09897
    Effects of gamma rays on the immunogenicity (IgG types) of ovalbumin
    2004 - BAPTISTA, J.A.; SPENCER, P.J.; AROEIRA, L.G.S.; CASARE, M.S.; NASCIMENTO, N.
  • Artigo IPEN-doc 09896
    Effects of sup(60)Co radiation on the molecular structure of crotamine
    2004 - CASARE, M.S.; BAPTISTA, J.A.; SPENCER, P.J.; NASCIMENTO, N.
  • Artigo IPEN-doc 11180
    In vitro antileishmanial properties of neutron-irradiated meglumine antimoniate
    2005 - BORBOREMA, S.E.T.; ANDRADE JUNIOR, H.F.; OSSO JUNIOR, J.A.; NASCIMENTO, N.
    Pentavalent antimony, as meglumine antimoniate (Glucantime) or sodium stibogluconate (Pentostam), is the main treatment for leishmaniasis, a complex of diseases caused by the protozoan Leishmania, and an endemic and neglected threat in Brazil. Despite over half a century of clinical use, their mechanism of action, toxicity and pharmacokinetic data remain unknown. The analytical methods for determination of antimony in biological systems remain complex and have low sensitivity. Radiotracer studies have a potential in pharmaceutical development. The aim of this study was to obtain a radiotracer for antimony, with suitable physical and biological properties. Meglumine antimoniate was neutron irradiated inside the IEA-R1 nuclear reactor, producing two radioisotopes 122Sb and 124Sb, with high radionuclidic purity and good specific activity. This compound showed the same antileishmanial activity as the native compound. The use of the radiotracers, easily created by neutron irradiation, could be an interesting tool to solve important questions in antimonial pharmacology.
  • Artigo IPEN-doc 11621
    Study of gamma-radiation effects on crotamine and crotoxin
    2006 - CASARE, M.S.; SPENCER, P.; CAMPOS, L.A.; NASCIMENTO, N.
    Crotoxin is a 23 kDa neurotoxin from Crotalus durissus terrificus and is composed of a 9 kDa acidic subunit (crotapotin) and a 14 kDa basic subunit (phospholipase A2). Crotamine is 4882 Da, basic polypeptide with myotoxic activity. These toxins, when submitted to gamma-rays, in aqueous solution, present structural modifications, preserving their immunogenic properties. In the present work, we investigated some structural modifications on both crotoxin and crotamine after gamma-radiation using various doses, in the presence or not of "scavenger" substances. Our results indicate that irradiation leads to progressive changes in the structure of the toxin, which could explain the lower toxicity observed.
  • Artigo IPEN-doc 14083
    Study of irradiated bothropstoxin-1 with sup(6)Co gamma rays: immune system behavior
    2009 - CAPRONI, P.; BAPTISTA, J.A.; ALMEIDA, T.L. de; PASSOS, L.A.C.; NASCIMENTO, N.
    Ionizing radiation has been successfully employed to modify the immunological properties of biomolecules. Very promising results were obtained when crude animal venoms, as well as isolated toxins, were treated with 60Co gamma rays, yielding toxoids with good immunogenicity. The achievement of modified antigens with lower toxicity and preserved or improved immunogenicity can be very useful. Ionizing radiation has already been proven to be a powerful tool to attenuate snake venom toxicity without affecting, and even increasing, their immunogenic properties. However, little is known about the modifications that irradiated molecules undergo and even less about the immunological response that such antigens elicit. In the present work, we investigated the immunological behavior of bothropstoxin-1, a K49 phospholipase, before and after irradiation. Structural modifications of the toxin were analyzed by SDS-PAGE. Isogenic mice were immunized with either the native or the irradiated toxin. The circulating antibodies were isotyped and titrated by ELISA. According to our data, irradiation promoted structural modifications in the toxin characterized by higher molecular weight forms of proteins (aggregates and oligomers). The results also indicated that irradiated toxins were immunogenic and antibodies elicited by them were able to recognize the native toxin in ELISA. These findings suggest that irradiation of toxic proteins can promote significant modifications in their structures; however they still retain many of the original antigenic and immunological properties of native proteins. Also, our data indicate that irradiated proteins induce higher titers of IgG2a and IgG2b, suggesting that Th1 cells are predominantly involved in the immune response.