Navegando por Palavras-chave "Monocamadas"

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    Avaliação da interação molecular de 1,4 naftoquinona em modelos de membrana celular utilizando filmes de Langmuir
    (Universidade Federal de São Paulo, 2014-01-31) Hussein, Nadia [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Cancer is a disease characterized by the uncontrolled multiplication and spread of abnormal forms of cells. In order to treat cancer, anticancer drugs were used, which are natural or organosynthetic compounds that act against the development of cancer cells and tumor growth. In this group, we can include 1,4- naphthoquinone, which is present in various chemotherapeutics. It is a derivative of vitamin K, and a potent inhibitor of cell growth and tumor angiogenesis. Thus, this study aims to understand at the molecular level the interaction between this drug and cell membrane by means of simplified models of cell membrane (Langmuir monolayers formed by lipids). For this purpose, we performed measurements of surface tensiometry, curved surface pressure - area and infrared spectroscopy. For that, we employed the phospholipid DPPC (dipalmitoylphosphatidylcholine) for the formation of lipid monolayers (Langmuir films) which mimicked a healthy cell membrane, and DPPS (dipalmitoylphosphatidyl serine), representing cancerous membranes. Rabbit aorta endothelialcell cultures for healthy and tumorigenic cells were also employed. Phospholipids were spread on aqueous solutions, and surface pressure – area isotherms and infrared spectra were obtained. After that, different amounts of 1,4- naphthoquinone were added to the lipid monolayer and new isotherms and spectra were obtained . Similar procedures were performed with cell cultures. Three phenomena were observed due to the interaction between the monolayer and the drug: 1 ) the isotherms were shifted to smaller molecular areas, 2) 1,4- naphthoquinone increased the compressibility of the monolayer , causing a disruption in the organization of the film, which was confirmed later by infrared spectroscopy, and 3) the phase transitions has not been well defined in the surface pressure-area isotherms, suggesting a non-ideal mixture, due to interactions between the drug and the monolayer. For cell cultures, whereas minor changes were observed for cultures representing non-tumorigenic cells after the incorporation of the drug, significant changes were observed for cultures representing tumorigenic cells. Therefore, we conclude that 1,4-naphthoquinone interacts with cell membrane models represented by monolayers of DPPC, DPPS and cell cultures studied with a more expressive interaction with models of tumorigenic cells.
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    Efeito Da Chia ( Salvia Hispanica L) Sobre Parâmetros Metabólicos E Inflamatórios No Diabetes Mellitus, Em Camundongos
    (Universidade Federal de São Paulo (UNIFESP), 2017-11-30) Oliveira, Cinthia Romeika De [UNIFESP]; Silveira, Vera Lucia Flor [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Introduction and Objectives: Diabetes mellitus (DM) is a chronic disease, characterized by hyperglycemia, which may be caused by the absence or deficient of insulin secretion or peripheral resistance to this hormone. As a consequence of this alteration, the adipose tissue of individuals with type 2 DM (DM2), presents high rates of lipolysis, aggravating the existing insulin resistance. Several studies have shown the importance of omega-3 polyunsaturated fatty acids (PUFAs w-3) as complementary therapy in the treatment of chronic diseases, including DM. Studies have shown that these PUFA decrease the inflammatory process and may improve insulin resistance. chia seeds, which has the vegetable oil with the highest concentration of PUFAs w-3, known until now, has been widely used by the population for reduction of weight, cholesterol and triglyceride, and also prevention of diabetes and cardiovascular diseases. However, the scientific papers which study these relations are few and still quite contradictory. This study aims to analyze the preventive effect of dietary supplementation with chia oil on metabolic and inflammatory parameters in mice submitted to the DM2 model, induced by hyperlipidic diet and streptozotocin (STZ). For this, we used male C57bl / 6 mice, divided into three groups: control (C), diabetic (D) and diabetic treated with chia (DC). The animals in group C received a normolipidic diet for 6 weeks and the animals in groups D and DC received a hyperlipidic diet and daily doses of water (D) or chia oil (DC). At the end of the third week of feeding, animals in groups D and DC were induced to partial insulin deficiency by 1 dose (45mg / kg) of STZ during 5 consecutive days. At the end of the sixth week the mice were euthanized, blood, liver and adipose tissues removed. Results and Conclusions: Preventive treatment with chia oil promoted beneficial effects such as decrease body mass gain without modifying caloric and energy consumption, reduction of visceral fat, lipolysis and adipocyte volume of the epididymal tissue and increase of HDL- c. However, although this treatment partially improved glucose tolerance, it did not improve insulin resistance. It appears that the beneficial effects induced by chia in lipid metabolism were not sufficient for the improvement of insulin resistance required for the treatment of DM2.
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    Interação da enzima lactase em filmes fosfolipídicos de Langmuir e Langmuir-Blodgett: possível aplicação para biossensores para lactose
    (Universidade Federal de São Paulo, 2017-10-06) Ayoub, Fabio de Paula [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    In this work the interaction of the enzyme lactase in Langmuir and Langmuir-Blodgett (LB) films of the phospholipid dimyristoylphosphatidic acid (DMPA) was studied. The phospholipid was spread at the air-water interface forming Langmuir monolayers, and the enzyme was inserted into the aqueous subphase that supported the lipid monolayer. The adsorption of the enzyme to the monolayer was studied by surface pressure-area isotherms, surface potential-area isotherms, Brewster angle microscopy, and by vibrational spectroscopy. The mixed monolayers phospholipid + enzyme was transferred to solid supports by the LB methodology and characterized by luminescence spectroscopy, vibrational spectroscopy, atomic force microscopy and nanogravimmetry by quartz crystal microbalance. The enzymatic activity of the lactase immobilized as LB film was evaluated and compared to the hydrolysis of lactose to glucose and galactose using UV-visible spectroscopy. As conclusion, the enzyme can be inserted into the lipid films, maintaining partially its secondary structures, and altering the morphology of the LB films. The catalytic activity could be maintained up to 84% of the activity in relation to the homogeneous medium, which makes the system feasible for future applications in lactose biosensors.