Navegando por Palavras-chave "Silica"

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    Caracterização farmacológica da Crotamina sintética como antitumoral em modelos de melanoma in vivo. Otimização da atividade neoplásica com uso de adjuvantes
    (Universidade Federal de São Paulo (UNIFESP), 2020-05-28) Porta, Lucas De Carvalho [UNIFESP]; Hayashi, Mirian Akemi Furuie [UNIFESP]; Universidade Federal de São Paulo
    Toxins are of great scientific interest, mainly due to their possible use for therapeutic purposes as drugs, or as a structural model for its development. Crotamine, which is one of the most abundant toxins present in the rattlesnake venom, can penetrate cells, with special specificity and cytotoxic activity against active proliferating cells. Daily treatment of animal models of melanoma, with crotamine administered through intraperitoneal or oral routes, showed a significant remission of tumor growth such as an increase in survival of the treated animals. In order to continue and improve the anti-tumor treatment with crotamine, the present work consisted to show the use of crotamine obtained by chemical synthesis, associated with thioridazine or with silica nanoparticles in the therapy of animal models of melanoma, such as the evaluation of treatment-related toxicity through the administration of these associated compounds in isolated skeletal muscle or with high doses injections in vivo. The remission of tumor growth in vivo was evaluated comparing these associations/formulations with the effect of native crotamine alone, suggesting that, although significant toxicity has been observed in the treatment with crotamine associated with thioridazine, which is not due to local effect, it is feasible to decrease the amount of crotamine needed for anti-tumor treatment.
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    Exposição ocupacional à sílica no Brasil no ano de 2001
    (Associação Brasileira de Saúde Coletiva, 2008-03-01) Ribeiro, Fátima Sueli Neto; Camargo, Esther Archer De; Algranti, Eduardo; Wünsch Filho, Victor; Universidade do Estado do Rio de Janeiro; Instituto Nacional do Câncer; Universidade de Federal de São Paulo Departamento de Enfermagem; Fundacentro Centro Técnico Nacional Divisão Medicina; Universidade de São Paulo (USP)
    OBJECTIVE: To estimate the number of Brazilian workers exposed to silica in 2001. METHODS: Information on occupation and industry for the year 2001 was linked through a job exposure matrix (JEM) of 347 job categories in 25 industries. Data on the number of workers were extracted from the National Workforce Database of the Ministry of Labor and Employment. Two experts classified silica exposure according to frequency in four categories, according to weekly proportion of exposure to silica in the work environment. RESULTS: 31,451,594 (85.7%) workers were classified as not exposed; 976,939 (2.65%) as possibly exposed; 2,404,955 (6.52%) as probably exposed; and 2,065,929 (5.6%) as definitely exposed to silica. Industries with a higher prevalence were: construction 65%, quarrying 59%, manufacturing of non metallic mineral products 55%, manufacturing of basic metals 24%, and rent of machinery and other business activities 2%. CONCLUSIONS: The prevalence of Brazilian workers definitely exposed to silica is higher than the one observed in European countries, where similar studies were conducted.
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    Synthesis and Characterization of Methylene Blue-Containing Silica-Coated Magnetic Nanoparticles for Photodynamic Therapy
    (Amer Scientific Publishers, 2017) Fudimura, Karina Amancio [UNIFESP]; Seabra, Amedea Barozzi [UNIFESP]; Santos, Marconi da Cruz [UNIFESP]; Haddad, Paula Silvia [UNIFESP]
    Superparamagnetic iron oxide nanoparticles (SPIONs), with appropriate surface coating, are commonly used for biomedical applications such as photodynamic therapy (PDT). This work describes the preparation and characterization of methylene blue (MB)-containing silica-coated SPIONs. Upon exposure to light, MB reacts with molecular oxygen and generates singlet oxygen (O-1(2)) which is cytotoxic and causes irreversible damage to tumor tissues. In this work, SPIONs were synthesized by co-precipitation and coated with a single/double silica layer. The photoactive molecule MB was entrapped in the silica layer deposited on the surface of SPIONs, leading to the formation of hybrid nanomaterials composed of a magnetic core and silica layer. The nanocomposite exhibited magnetic behavior at room temperature due to the presence of its Fe3O4 core. Structural and morphological characterizations were performed by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), SQUID magnetic measurements, ultraviolet-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and dynamic light scattering. The results showed the presence of a crystalline Fe3O4 magnetic core and amorphous silica phases. Kinetic measurements revealed O-1(2) generation by the nanoparticles upon irradiation with visible light (lambda = 532 nm or lambda = 633 nm). The results highlight the potential uses of SPIONs coated with MB-entrapped silica for PDT, whereby a sustained and localized generation of O-1(2) was successfully achieved.