304 research outputs found
Desenvolvimento de nanopartícula lipídica sólida contendo um análogo de pirimidina e avaliação in vitro da atividade antitumoral
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Farmácia, Florianópolis, 2014Esta tese está sendo apresentada em quatro etapas. A primeira foi avaliar doze moléculas de análogos de pirimidina, quanto ao aspecto de citotoxicidade e tipo de morte celular em três linhagens celulares tumorais (L1210, B16F10 e CEM). Quatro moléculas apresentaram efeito citotóxico relevante. Assim, prosseguiu-se a avaliação da molécula C3, escolhida entre as quatro pela facilidade de obtenção.Testes preliminares apresentaram baixa solubilidade em água, o que dificultaria a administração parenteral. Desta maneira, a segunda etapa foi desenvolver uma formulação para facilitar a administração desta molécula in vivo. Neste sentido, foi realizada a avaliação da influência do emulsionante e do tipo de lipídeo nas características físico-químicas e na biocompatibilidade de nanopartículas lipídicas sólidas (NLS). Formulações foram preparadas com diferentes lipídeos (tripalmitina (TRP), monoestearato de glicerila (MEG) e ácido esteárico (AE)) e emulsionantes (polissorbato 80 e lecitina S75) em diferentes concentrações. Os estudos de biocompatibilidade celular realizados foram: viabilidade celular por MTT, análise da morfologia celular por laranja de acridina, ciclo celular por citometria de fluxo e hemólise de eritrócitos. As formulações demonstraram boa estabilidade físicoquímica e apresentaram um tamanho de partícula entre 116 a 306 nm, com índice de polidispersão (PI) entre 0,25 a 0,30 com valores negativos para o potencial zeta (PZ). As NLS produzidas com AE mostraram maior citotoxicidade in vitro quando comparadas com as NLS produzidas com TRP e MEG e apresentaram atividade hemolítica. A terceira etapa foi otimizar uma formulação de NLS aplicando um delineamento experimental. A partir desta otimização, NLS foram preparadas pelo método de ultrassom e o C3 foi incorporado em diferentes concentrações (250, 500 e 1000 µg.mL-1). Um método por cromatografia líquida de alta eficiência foi desenvolvido e validado para o doseamento do C3 incorporado nas NLS. A adição de diferentes quantidades de C3 nas formulações não afetou o diâmetro médio das nanopartículas. O PI foi menor que 0,22 para todas as formulações. O PZ das NLS apresentram valor negativo e houve variações entre as formulações preparadas indicando a adsorção do C3 na superfície das nanopartículas. A eficiência de encapsulação foi maior que 97% para as formulações desenvolvidas. O estudo de estabilidade revelou expulsão do C3 da NLS ao longo do tempo, assim um estudo de liofilização foi realizado. Boas características de ressuspensão foram atingidas e o teor de C3 foi mantido ao longo do tempo. O ensaio de liberação indicou uma eficiência na retenção do C3 pelas NLS. No estudo de citotoxicidade com linhagem celular tumoral L1210, as NLS contendo a molécula encapsulada apresentou um perfil de toxicidade semelhante à molécula livre. Por fim, como quarta etapa deste trabalho, visando facilitar uma possível passagem de escala, foi realizada uma comparação das características das NLS produzidas pela técnica de utltrassonicação e de homogeneização por alta pressão. Como conclusão, os resultados obtidos revelaram a capacidade de incorporação de uma molécula pouco solúvel em NLS, o que viabiliza a administração parenteral e torna este sistema adequado para testes in vivo.Abstract: This thesis is presented in four steps. The first step in this work was the evaluation of the cytotoxicity of twelve pyrimidine analogs in three cell lines (L1210, B16F10 and CEM) and to assess the type of cell death induced by these molecules. Four molecules showed significant cytotoxic effect. Thus, C3 molecule was chosen to continue the study because it is easy to obtain it. Preliminary tests showed low solubility of the molecule in water, making it difficult to parenteral administration. Therefore, the second step was to develop a formulation to facilitate the administration of this molecule in vivo. In this regard, a review of the preliminary influence of the emulsifier and the lipid type on the physicochemical characteristics and biocompatibility of solid lipid nanoparticles (SLN) were performed. Formulations were prepared with lipids commonly used for production of SLN (tripalmitin (TRP), glyceryl monostearate (MEG) and stearic acid (SA) and emulsifiers(polysorbate 80 and lecithin S75) at different concentrations. Cell biocompatibility studies were performed: cell viability by MTT analysis of cell morphology with acridine orange stain, cell cycle by flow cytometry and hemolysis of erythrocytes. The formulations studied showed good physical-chemical stability and they showed the particlesize between 116 and 306 nm, polydispersity index (PI) 0.25 and 0.30 with negative zeta potencial (PZ) values. The SLN manufactured using SA showed greater cytotoxicity in vitro when compared to SLN produced with MEG and TRP, and SNL-SA showed hemolytic activity.The third step was to optimize a formulation of NLS applying an experimental design. The optimized formulation was prepared by the ultrasound method and C3 was incorporated at different concentrations in SLN (250, 500 and 1000 µg.mL-1). A high performance liquid chromatographic (HPLC) method was developed and validated for the quantitative determination of C3 in SLN. The addition of different amounts of C3 in the formulation did not affect the mean diameter of the nanoparticles. The PI was less than 0.22 for all formulations. PZ of the SLN showed a negative value and there were variations among the formulations prepared indicating adsorption of the C3 on the surface ofnanoparticles. The encapsulation efficiency was higher than 97% for allthe formulations developed. The stability study revealed expulsion ofthe C3 in SLN over time, and for this a lyophilisation study was conducted. Good proprieties of resuspension were established and the formulations stability were maintained over time. The release assay indicated a retention of the C3 in NLS. The cytotoxicity study with L1210 cell lines the SLN containing C3 encapsulated showed a similar profile to the free-molecule cytotoxicity. Finally, as a fourth step of this work, to facilitate a possibility to scale up, a comparison of the SLN physicochemical proprieties produced by the ultrasound method and high pressure homogenization was performed. The results showed that both techniques are suitable for the production of SLN. In conclusion, these findings suggest that a pyrimidine analogue loaded solid lipid nanoparticle is a promising formulation for parenteral administrations and that it suitable for in vivo testing
Transgene construct and the NLS-I-SceI molecule.
No full text<p>A: The schematic structure of p2IS-UBC-eGFP vector. IS site: the inversely flanking I-SceI recognition sequence; the black bar indicates the position of the probe used for Southern blot assay. B: The schematic structure of NLS-I-SceI molecule. C: The <i>in vitro</i> transcribed NLS-I-SceI mRNA. polyA+: the mRNA with polyA tail; polyA-: the mRNA without polyA tail. D: The expected working principle of NLS-I-SceI-mediated transgenesis.</p
A Stochastic Parametrically-Forced NLS Equation
No full textIn this thesis, a variation on the nonlinear Schrödinger (NLS) equation with multiplicative noise is studied. In particular, we consider a stochastic version of the parametrically-forced nonlinear Schrödinger equation (PFNLS), which models the effect of linear loss and the compensation thereof by phase-sensitive amplification in pulse propagation through optical fibers. We establish global existence and uniqueness of mild solutions for initial data in L2(R) and H1(R).The proof is an adaptation of a fixed-point argument employed by de Bouard and Debussche [Comm. Math. Phys., 205:161-181, 1999] for the nonlinear Schrödinger equation with multiplicative noise. The fixed-point argument relies on space-time estimates on the semigroup generated by the linear parametrically-forced Schrödinger operator. We prove these so-called Strichartz estimates, originally proven for the Schrödinger operator, using Fourier methods. A key difference between the Schrödinger operator and its parametrically-forced version is that the latter is not self-adjoint. We overcome this complication by establishing fixed-time estimates on the semigroup and its adjoint, based on their Fourier representations. We also briefly discuss possible future research in the direction of stability of solitary standing wave solutions of the PFNLS equation under the influence of multiplicative noise. Using informal calculations, we demonstrate an approach to track the displacement of a soliton due to small stochastic forcing.Applied Mathematic
A COMPACT ATTRACTOR FOR ENERGY CRITICAL AND SUPER-CRITICAL NLS
No full textWe show existence of a compact attractor for NLS in energy critical and super-critical cases basing on the method of Tao [12]
Poincaré-Dulac normal form reduction for unconditional well-posedness of the periodic cubic NLS
No full textWe implement an infinite iteration scheme of Poincare-Dulac normal form reductions to establish an energy estimate on the one-dimensional cubic nonlinear Schrodinger equation (NLS) in C_t L^2(T), without using any auxiliary function space. This allows us to construct weak solutions of NLS in C_t L^2(T)$ with initial data in L^2(T) as limits of classical solutions. As a consequence of our construction, we also prove unconditional well-posedness of NLS in H^s(T) for s \geq 1/6
Long Time Dynamics of the 3D Radial NLS with the Combined Terms
No full textIn this paper, we study the scattering and blow-up dichotomy result of the radial solution to nonlinear Schrodinger equation (NLS) with the combined terms i(ut) + Delta u = -vertical bar u vertical bar(4) u + vertical bar u vertical bar(p-1) u, 1 + 4/3 < p < 5 in energy space H-1 (R-3). The threshold energy is the energy of the ground state W of the focusing, energy critical NLS, which means that the subcritical perturbation does not affect the determination of threshold, but affects the scattering and blow-up dichotomy result with subcritical threshold energy. This extends algebraic perturbation in a previous work of Miao, Xu and Zhao [Comm. Math. Phys., 318, 767-808 (2013)] to all mass supercritical, energy subcritical perturbation.NSFC [11171033, 11231006]SCI(E)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)[email protected]; [email protected]
The periodic Cauchy problem for PT-symmetric NLS, I: the first appearance of rogue waves, regular behavior or blow up at finite times
No full textThe recently discovered PT-symmetric nonlinear Schrödinger (PT–NLS)
equation is an integrable nonlinear and nonlocal dispersive model. In the focusing
case, monochromatic perturbations of the constant background solution with
sufficiently small wave number are modulationally unstable and one expects
the formation of rogue waves (RWs), as for the celebrated focusing nonlinear
Schrödinger (NLS) equation. In this paper we investigate the x-periodic
Cauchy problem of PT–NLS, for a generic periodic initial perturbation of the
constant background solution (what we call the periodic RW problem), in the
simplest case of one unstable mode only. We use matched asymptotic expansion
techniques to study the first appearance of RWs, well described by two recently
discovered exact solutions of PT–NLS, whose free parameters can be expressed
in terms of the initial data through elementary functions. Depending on the initial
data, the rogue waves are either regular, with arbitrarily large amplitude, or they
blow up twice at the first appearance, unlike the NLS case, in which the RWs
are always regular and with fixed amplitude. A qualitative reason for it should
be the gain-loss properties of the complex self-induced potential of PT–NLS,
that could cause extra-focusing effects with respect to the NLS case. This paper
is motivated by recent works of Grinevich and the author in which a similar
approach, as well as the finite gap method, have been used to solve the RW
periodic Cauchy problem for the focusing NLS equation
Chromatin-bound NLS proteins recruit membrane vesicles and nucleoporins for nuclear envelope assembly via importin-α/β
No full textThe mechanism for nuclear envelope (NE) assembly is not fully understood. Importin-ß and the small GTPase Ran have been implicated in the spatial regulation of NE assembly process. Here we report that chromatin-bound NLS (nuclear localization sequence) proteins provide docking sites for the NE precursor membrane vesicles and nucleoporins via importin-a and -ß during NE assembly in Xenopus egg extracts. We show that along with the fast recruitment of the abundant NLS proteins such as nucleoplasmin and histones to the demembranated sperm chromatin in the extracts, importin-a binds the chromatin NLS proteins rapidly. Meanwhile, importin-ß binds cytoplasmic NE precursor membrane vesicles and nucleoporins. Through interacting with importin-a on the chromatin NLS proteins, importin-ß targets the membrane vesicles and nucleoporins to the chromatin surface. Once encountering Ran-GTP on the chromatin generated by RCC1, importin-ß preferentially binds Ran-GTP and releases the membrane vesicles and nucleoporins for NE assembly. NE assembly is disrupted by blocking the interaction between importin-a and NLS proteins with excess soluble NLS proteins or by depletion of importin-ß from the extract. Our findings reveal a novel molecular mechanism for NE assembly in Xenopus egg extracts.Cell Research advance online publication 31 July 2012; doi:10.1038/cr.2012.113
Frequency-uniform decomposition method for the generalized BO, KdV and NLS equations
No full textAbstractSufficient and necessary conditions for the embeddings between Besov spaces Bp,qs1 and modulation spaces Mp,qs2 are obtained. Moreover, using the frequency-uniform decomposition method, we study the Cauchy problem for the generalized BO, KdV and NLS equations, for which the global well-posedness of solutions with the small rough data in certain modulation spaces M2,1s is shown
SRD5A2 (steroid-5-alpha-reductase, alpha polypeptide 2 (3-oxo-5 alpha-steroid delta 4-dehydrogenase alpha 2))
No full textReview on SRD5A2 (steroid-5-alpha-reductase, alpha polypeptide 2 (3-oxo-5 alpha-steroid delta 4-dehydrogenase alpha 2)), with data on DNA, on the protein encoded, and where the gene is implicated
- …
