224 resultados para Citotoxidade de mediação celular


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Bacillus thuringiensis (Bt), is an environmental Gram-positive spore-forming bacterium that produces crystalline parasporal protein (Cry) during sporulation. The inclusions often exhibit strong and specific insecticidal activity, making Bt an agent for agricultural controlling insects pest, mites, protozoa and nematodes. Recent studies reported that some of these Crys do not show cytotoxicity against insects but they are capable to kill some human and animal cancer cells. These proteins were denominated parasporins (PS). However, antitumor activity of Bt parasporin on the development of murine colorectal cancer (CT-26), are not well studies and these are no reports on the in vivo effect of these proteins. Thus, the present study evaluated the in vitro and in vivo anti-tumoral activity of Bt parasporin against the murine colorectal cancer line CT-26. Therefore, Balb/c mice were s.c. inoculated with CT-26 cells and weekly treated with parasporin (i.p.) pre-activated by enzymatic digestion with trypsin or proteinase K. Our results have shown, for the first time, that despite the anti-tumor activity in vitro, parasporin crystals couldn’t combat tumor growth in vivo. Instead, this protein was highly toxic, affecting the liver and spleen, with possible effect on other organs, decreasing the survival of treated animals. The results indicate the need for studies to better detoxification or manipulation of parasporin for therapeutic use and new studies for analysis of toxicological effects of repetitive exposure of farmers to this toxin

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Reabilitação Oral - FOAR

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Avaliaram-se os coeficientes de digestibilidade do extrato etéreo (EE), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), hemicelulose (HCEL) e celulose (CEL) de uma ração completa, composta por 44,3% de feno de braquiária, 55% de concentrado e 0,7% de mistura mineral, fornecida a bovinos de diferentes grupos genéticos (Gir, Nelore, Guzerá, Santa Gertrudis e Caracu), pelas metodologias de coleta total de fezes e com indicador interno (lignina em detergente ácido - LDA), em delineamento inteiramente casualizado, com três repetições por grupo genético, com análise de variância individual dentro de cada metodologia e uma análise de correlação entre as metodologias. Não houve diferença entre grupos genéticos para a digestibilidade de EE, PB, FDN, FDA, HCEL e CEL, pelas metodologias de coleta total de fezes e com LDA, com médias de 44,28 e 40,38%; 52,46 e 49,51%; 57,04 e 54,25%; 37,71 e 34,04%; 71,66 e 69,68%; e 48,27 e 45,20%, respectivamente. As digestibilidades da PB, FDA e CEL não mostraram correlação. A LDA foi eficiente na estimativa da digestibilidades e os nutrientes foram utilizados de forma semelhante pelos diferentes grupos genéticos.

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Background: Embryonic stem cells are cells derived from early-stage embryos that are characterized by pluripotency and self-renewal capacity. The in vitro cultured murine embryonic stem cells can indefinitely propagate in an undifferentiated state in the presence of leukemia inhibitory factor (LIF). However, when stimulated, these cells can differentiate into cell lines derived from all three embryonic germ layers. The trichostatin A (TSA) is an epigenetic modifier agent and several studies have used the TSA to stimulate cellular differentiation. However, most of these studies only assessed one TSA concentration. Therefore, this study aimed to evaluate the effects of different TSA concentrations on histone hyperacetylation during in vitro cell differentiation of murine pluripotent embryonic stem cells, cultured with or without LIF, in the quest of to standardize their application on early cultures of embryonic stem cells.Materials, Methods & Results: Undifferentiated murine embryonic stem cells were plated in the presence of different TSA concentrations (0 nM, 15 nm, 50 nM and 100 nM) in the presence or absence of LIF. Thus, the treatments were evaluated in undifferentiated embryonic stem cells cultured in the presence of LIF (Control group: 0 nM LIF(+); Group 15 nM LIF+; Group 50 nM LIF+ and Group 100 nM LIF+), and in embryonic stem cells cultured in the absence of LIF (Control group: 0 nM LIF; Group 15 nM LIF(-); Group 50 nM LIF(-) and Group 100 nM LIF-). Treatment with TSA was performed for 24 h. After that the medium was replaced with fresh medium without TSA. Samples were collected at 0, 12, 24, 36 and 48 h after the beginning of the experiment. Three replicates were performed in each experimental group. The relative amount of Histone H3 lysine 9 acetylation was analyzed in all groups, as well as the cell proliferation in the embryonic stem cells cultured in the presence of LIF. In the control group (0 nM), the absence of LIF resulted in higher levels (P < 0.05) of H3lys9ac compared to the cultures supplemented with LIF. In the embryonic stem cells cultured in the presence of LIF, the 50 nM and 100 nM treatments resulted in higher levels (P < 0.05) of H3lys9ac when compared with 0 nM and 15 nM treatments. Evaluating the Hoechst area in the 0 nM group, it was observed that the number of cells increased (P < 0.05) according to the time of culture. Treatment with 15 nM also reflected a similar distribution, but the Hoechst area in 15 nM group was lower (P < 0.05) at 24 and 48h when compared to the observed in the control group. In the 100 nM treatment, was observed that the area of Hoechst was lower (P < 0.05) to that obtained in the control group at 12, 24 and 48h. In addition, it was observed that treatment with TSA induces greater cellular differentiation when compared to control groups in stem cells cultured in the presence of LIF as well as in the absence of LIF.Discussion: In the present study it was observed that TSA treatment increased the levels of histone acetylation in murine embryonic stem cells at a 50 nM concentration, making it possible to reduce the concentration recommended in the literature (100 nM). In addtion, it was concluded that the lower TSA concentrations utilized (15 nm and 50 nM) was less harmful to cellular proliferation than the 100 nM TSA concentration.

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Mangas 'Tommy Atkins' produzidas na região de Ibirá, São Paulo, foram pulverizadas na pré-colheita com cloreto de cálcio, nas concentrações de 0,0%, 2,5% e 5,0%, em três épocas de seu desenvolvimento (40; 60 e 90 dias após a floração) a fim de verificar a influência do cálcio na estrutura da parede celular destes frutos através de microscopia eletrônica de transmissão, imediatamente após a colheita e depois de 35 dias de armazenamento. Para fixar o material da polpa, utilizou-se metodologia descrita por Jacob e Gowanlock (1995). Nas condições experimentais, verificou-se que os frutos do tratamento-controle (sem cloreto de cálcio), no dia da colheita, já apresentavam desestruturação da parede celular e dissolução da lamela média (LM). A degradação da parede celular ocorre inicialmente na LM, levando à formação de espaços vazios bastante distintos, apresentando uma dissolução ainda maior, com o armazenamento prolongado (35 dias). Os frutos tratados com cloreto de cálcio a 5,0% apresentaram uma LM bem definida e ausência de espaços vazios, mesmo após o armazenamento, mostrando ser uma concentração efetiva na preservação da lamela média.