Navegando por Palavras-chave "Gamma radiation"

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    Can gamma-radiation modulate hemagglutinating and anticoagulant activities of PpyLL, a lectin from Phthirusa pyrifolia?
    (Elsevier Science Bv, 2017) Costa, Romero M. P. B.; Campos Albuquerque, Wendell Wagner; Silva, Mariana C. C. [UNIFESP]; de Paula, Raiana Apolinario; Melo, Mychely Sheila; Oliva, Maria L. V. [UNIFESP]; Figueiredo Porto, Ana Lucia
    Blood coagulation and platelet-dependent primary homeostasis are important defense mechanisms against bleeding and novel inhibitors have been researched to obtain pharmacological and clinical applications. In this work, the PpyLL, a lectin obtained from Phthirusa pyrifolia, was characterized in terms of its molecular structure and biological functions (anticoagulant, antiplatelet agreggation and hemagglutinating activities) in presence or absence of Gamma radiation exposure. Results revealed a lectin with secondary-structure content by approximately 49% of beta-sheet, 20% of beta-turn and 31% of disordered structure. Irradiation effect demonstrated possible different sites of function by lectin on anticoagulant and hemagglutinating activities, once a decrease about 80% was observed when compared the activities under 0.5 kGy of exposition to gamma radiation. An emphatic discussion about the use of gamma radiation as a possible modulator of the lectin activity was made, and once the ionizing radiation affected differently the anticoagulation and hemagglutinating activities, we speculated that the results are determined by selective molecular damages in different binding sites. PpyLL biological activities and gamma radiation modulation could be considered for future researches in biomedical field aiming possible medical applications. (C) 2017 Elsevier B.V. All rights reserved.
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    Dosimetria ambiental de areia monazítica das praias do litoral norte de São Paulo
    (Universidade Federal de São Paulo, 2021-02-23) Teissiere, Luigi Leite [UNIFESP]; Tatumi, Sonia Hatsue [UNIFESP]; http://lattes.cnpq.br/5410340106554020; http://lattes.cnpq.br/2287413815393341; Universidade Federal de São Paulo (UNIFESP)
    Algumas praias do litoral norte de São Paulo apresentam areias monazíticas, que são areias que contêm terras raras e isótopos radioativos, deste modo, é possível afirmar que emite radiação gama. Quando o ser humano é exposto a doses de radiação, pode resultar em alguns danos celulares, podendo evoluir para um câncer. O objetivo deste trabalho é estabelecer uma análise da dose de radiação gama emitida pela areia e comparar com os limites estabelecidos pelos órgãos reguladores. Foi utilizado o Detector de Germânio Puro de Camberra e a Rigaku MiniFlex 300 para as análises de dose anual das areias colhidas e as suas estruturas cristalinas. As doses das amostras da Praia da Mococa foram as que mais se aproximaram do limite natural de 10 mSv/ano estabelecido pela CNEN. E também foram encontradas estruturas de terras raras com o método de Difração de Raios X.
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    Gamma Ray Irradiation of the Vasoactive Peptide Bradykinin Reveals a Residue- and Position-Dependent Structural Modification
    (Springer, 2010-06-01) Nardi, Daniela T. [UNIFESP]; Rosa, Jose C.; Jubilut, Guita N. [UNIFESP]; Miranda, Antonio [UNIFESP]; Nascimento, Nanci; Nakaie, Clovis R. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    In this work the effect of radical species generated by gamma ray irradiation of aqueous solution upon structure of vasoactive peptide bradykinin (BK, RPPGFSPFR) was investigated. Increasing doses of 1-15 kGy Co-60 gamma radiation were applied to BK solutions and a progressive degradation of its structure in a non-linear mode was observed. Two main peptide derivatives generated by these treatments were isolated and characterized through a combined amino acid analysis and daughter ion scanning mass spectrometry approach. Notably, it was observed that only the Phe residue located at position 8 and not 5 of BK was oxidized by reactive hydroxyl radical species given rise to Tyr(8)-BK and m-Tyr(8)-BK analogues. Comparative circular dichroism (CD) experiments of these peptides revealed that BK presents greater conformational similarity to Tyr(8)-BK than to m-Tyr(8)-BK. These results are in agreement with the biological potencies of these compounds measured in rat uterus and guinea pig ileum muscle contractile experiments. in summary, gamma irradiation of BK solutions revealed a residue- and surprisingly, position-structural modification effect of reactive radicals even in small peptides. Also of value for peptide chemistry field, the approach of applying controlled strong electromagnetic radiation in solution seems to be an alternative and unique strategy for generating, in some cases, peptides derivatives with uncommon structures and valuable for their further therapeutic potential evaluations.