Navegando por Palavras-chave "Cell membrane"
Agora exibindo 1 - 4 de 4
Resultados por página
Opções de Ordenação
- ItemAcesso aberto (Open Access)Efeito antitumoral do ácido graxo docosahexaenóico em células de glioblastoma humano(Universidade Federal de São Paulo (UNIFESP), 2017-02-24) Queiroz, Fernanda de Oliveira [UNIFESP]; Miranda Filho, Manoel de Arcisio [UNIFESP]; http://lattes.cnpq.br/2680038286691388; http://lattes.cnpq.br/4963386651580275; Universidade Federal de São Paulo (UNIFESP)Glioblastoma Multiforme is considered one of the most serious and common brain neoplasias, representing 50% of ali malignant tumors present in the brain. With a poor prognosis, half of the patients die within 1 year of diagnosis. Gliomas present great changes in their morphology, so they are considered tumors of high complexity. These morphological changes are one of the causes for resistance to existing therapies. In order to look for new alternatives for the treatment of these neoplasias, several compounds have been studied, among them, the fatty acids. Fatty acids are organic components, poorly soluble in water and play important roles in cell membranes and metabolic processes. They are divided into saturated and unsaturated. In order to understand the action of saturated fatty acids, palmitic acid and polyunsaturated fatty acids, docosahexaenoic acid (DHA) and arachidonic acid (AA) in head cancer, in this study we used glycoproteinoma multiforme cells from the T98G lineage. Different assays were performed to elucidate the mechanism of operation. Initially, cell viability tests were performed by MTT to observe whether these compounds cause death or the reduction of cell viability. In sequence, membrane fluidity tests were performed to understand the selectivity of DHA, since only this acid had a reduction in the viability of human glioblastoma cells. To understand and quantify the type of death, whether apoptotic or necrotic, flow cytometry and Co-incubation Hoechst 33342 / PI were performed at different concentrations and observed a higher AnexinN labeling in these cells. Nuclear morphological changes in T98G cells were observed from Hoechst .33342 cells. Data obtained showed fragmented, picnotic and condensed nuclei, which are characteristics of cellular apoptosis. Levels of reactive oxygen species were also performed. With the use of the DHE probe, we observed an increase in the production of reactive oxygen species (ROS), which indicates that the type of death we are observing is apoptosis. The viability of DHA is probably due to the induction of the production of high levels of ROS.
- ItemAcesso aberto (Open Access)Estudo da interação do metronidazol em modelos de membrana(Universidade Federal de São Paulo, 2018-05-24) Rodrigues, Jefferson Carnevalle [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Interactions of bactericidal and antiprotozoal drugs with cell membranes could be better understood at the molecular level if nanostructured systems are employed. This study aimed to study the action of the drug Metronidazole in Langmuir films of phospholipids, which are used as simple models of cell membranes. The phospholipids used were dipalmitoylphosphatidylcholine (DPPC), dipalmitoylfosfatil serine (DPPS) and dipalmitoylfosfatil glycerol (DPPG), cholesterol (COL), 1,2 Dioleoyl-sn-glycero-3-phosphocoline (DOPC), and combinations of glycoproteins with dipalmitoylphosphatidylcholine (GLICOP +DPPC), peptidoglycan with DPPG (Pep+DPPG) and lipopolysaccharides with DPPG (LPS+DPPG). The lipids were spread on the air-water interface, and the drug injected into the aqueous subphase. The adsorption of the drug was evaluated by surface pressure measurements, infrared spectroscopy and Brewster angle microscopy (BAM). The drug causes pronounced effects on pressure-area isotherms for DPPC, DPPS, DPPG, Cholesterol, Glycoproteins + DPPC, Lipopolysaccharides + DPPG and Peptidoglycans+DPPG condensing the monolayer (shifts the isotherms to smaller areas per molecules at a given pressure), but expanding DPPG and DPPE monolayers. Infrared spectroscopy shows significant changes in the bands related to the stretch of methyl, increasing the molecular order for DPPS, DOPC, DPPE monolayers, and mixtures of DPPC with glycoproteins, whereas for DPPG, DPPG + LPS and DPPG + Pep the molecular order has a decrease, can also be observed probable interactions in the hydrophilic regions of the film when in the presence of mixed monolayers (LPS + DPPG and Pep + DPPG). BAM images show that the surface morphology of the lipid monolayers also changed with the presence of the drug, causing molecular aggregation, but with different morphological configurations for each film. This shows that the interaction of Metronidazole in the monolayer is modulated by the lipid composition at the air-water interface, as well as the drug-lipid interactions. We hope these results have a relevant impact on the understanding of how bioactive compounds act in microbial cells and in the pursuit for proposals of mechanisms at the molecular level.
- ItemRestritoInteração da Sakuranetina em filmes de Langmuir contendo lipídios insaturados(Universidade Federal de São Paulo, 2023-10-17) Souza, Matheus Lima de [UNIFESP]; Caseli, Luciano [UNIFESP]; http://lattes.cnpq.br/8929162910172931; https://lattes.cnpq.br/1708239824339856Este projeto investigou a interação de sakuranetina, um flavonoide de promissora atividade farmacêutica, com monocamadas de fosfolipídios insaturados que serviram para mimetizar membranas celulares. Os fosfolipídios empregados foram o 2-Oleoil-1-palmitoil-sn-glicero-3-fosfocolina (POPC) e 2-Oleoil-1-palmitoil-sn-glicero-3-fosfoetanolamina (POPE). As monocamadas puras e mistas com o bioativo foram avaliadas através de experimentos de pressão superficial, microscopia no ângulo de Brewster (BAM) e espectroscopia de reflexão-absorção no infravermelho com modulação da polarização (PM-IRRAS). Os resultados permitem concluir que a sakuranetina apresenta interação com os fosfolipídios, devido a expansão dos filmes monomoleculares. O POPC sofreu redução na estabilidade e diminuição da elasticidade superficial frente a esse bioativo, provavelmente causados por rearranjos moleculares na interface. Interações são verificadas por PM-IRRAS entre o flavonoide e a porção polar e apolar do POPC. A contribuição viscosa ao filme misto diminuiu, diferentes domínios de densidade foram exibidos por BAM e histerese relevante não foi identificada. O POPE sofreu pequena redução da estabilidade termodinâmica, indicando que poucos rearranjos aconteceram na monocamada. Poucas agregações vistas nas imagens do BAM estão presentes na interface. Sakuranetina também aumentou a rigidez deste lipídio, mas a monocamada permaneceu essencialmente elástica e facilmente espalhável na superfície, tal qual o primeiro lipídio. Os resultados de PM-IRRAS indicaram interações com a porção polar e apolar do POPE, o que explica a expansão da monocamada. Isto posto, os dados permitem supor que a sakuranetina foi mais bem incorporada na camada monomolecular de POPE, e que membranas com POPC experienciariam maior interação e desestabilização na presença deste flavonoide.
- ItemSomente MetadadadosInteraction of polysaccharide-protein complex from Agaricus blazei with Langmuir and Langmuir-Blodgett films of phospholipids(Elsevier B.V., 2009-02-01) Schmidt, Thais F.; Pavinatto, Felippe J.; Caseli, Luciano [UNIFESP]; Gonzaga, Maria L. C.; Soares, Sandra A.; Ricardo, Nagila M. P. S.; Oliveira, Osvaldo N.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Fed CearaThe use of natural substances in health applications may be hampered by the difficulties in establishing the mechanisms of action, especially at molecular-level. the protein-polysaccharide complex extracted from the mushroom Agaricus blazei Murill, referred to as CAb, has been considered for treating various diseases with probable interaction with cell membranes. in this study, we investigate the interaction between CAb and a cell membrane model represented by a Langmuir monolayer of dimyristoyl phosphatidic acid (DMPA). CAb affects the structural properties of DMPA monolayers causing expansion and increasing compressibility. in addition, interaction with DMPA polar heads led to neutralization of the electrical double layer, yielding a zero surface potential at large areas per molecule. CAb remained at the interface even at high surface pressures, which allowed transfer of Langmuir-Blodgett (LB) films onto solid supports with the CAb-DMPA mixture. the mass transferred, according to quartz crystal microbalance (QCM) measurements, increased linearly with the number of deposited layers. With UV-vis absorption, fluorescence and FTIR spectroscopies, we confirmed that the LB films contain polysaccharides, proteins and DMPA. Therefore, the CAb biological action must be attributed not only to polysaccharides but also to proteins in the complex. (C) 2008 Elsevier Inc. All rights reserved.