940 resultados para larval release


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

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

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

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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In this work structural features of anionic microemulsions, containing the pharmaceutical biocompatible components soya phosphatidylcholine (SPC), eumulgin HRE 40 (EU) and sodium oleate (SO) as surfactant, cholesterol (CHO) as oil phase and aqueous buffer were studied. Microemulsions were formulated with and without the antitumor drug doxorubicin (DOX). The various microstructures characterized in the pseudo-temary phase diagram were analyzed by polarized light microscopy, small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) as well as by their ability to incorporate and release DOX. The experimental results demonstrated a correlation between the composition, the structural features and drug delivery. It was found that at higher cholesterol contents, the crystallization of CHO polymorph phases changed the mobility of DOX molecules. Droplets were formed with short-range spatial correlation from a microemulsion (ME) with a low surfactant:oil ratio. More ordered structures with lamellar arrangements formed by the increasing of the CHO proportions in the formulation may be due to CHO crystallization. The in vitro release of DOX showed that the presence of a high content of crystalline CHO prolongs the release of DOX from ME. The retention of DOX in the internal oil phase of the ME may modulate the drug release for a prolonged time. These results clearly demonstrate the potential of ME as a drug-delivery system. (c) 2007 Elsevier B.V. All rights reserved.

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Depending on the composition, the mixture of surfactant, oil and water, may form supramolecular aggregates with different structures which can significantly influence the drug release. In this work several microemulsion (ME) systems containing soya phosphatidylcholine (SPC) and eumulgin HRE40 (TM) (EU) as surfactant, cholesterol (O) as oil phase, and ultra-pure water as an aqueous phase were studied. MEs with and without the antitumoral drug doxorubicin (DOX) were prepared. The microstructures of the systems were characterized by photon correlation spectroscopy, rheological behavior, polarized light microscopy, small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD). The results reveal that the diameter of the oil droplets was dependent on the surfactant (S) amount added to formulations. The apparent viscosity was dependent on the O/S ratio. High O/S ratio leads to the crystallization of cholesterol polymorphs phases which restricts the mobility of the DOX molecules into the ME structure. Droplets with short-range spatial correlation were formed from the ME with the low O/S ratio. The increase of the cholesterol fraction in the O/S mixture leads to the formation of ordered structures with lamellar arrangements. These different structural organizations directly influenced the drug release profiles. The in vitro release assay showed that the increase of the O/S ratio in the formulations inhibited the constant rate of DOX release. Since the DOX release ratio was directly dependent on the ratio of O/S following an exponential decay profile, this feature can be used to control the DOX release from the ME formulations. (C) 2008 Elsevier B.V. All rights reserved.

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The alteration of minerals in rocks and the availability of elements for plant nutrition require long periods of time, and microorganisms are thought to induce the release of potassium and phosphate from rocks. In this context, this work evaluates the role of the yeast Torulaspora globosa, isolated from the sugar cane rhizosphere, in the solubilization of potassium from alkaline ultramafic rock powder. The experiments were performed in liquid medium, with or without agitation, at 30°C with the following treatments: culture medium + alkaline ultramafic; culture medium + yeast suspension; and culture medium + yeast suspension + alkaline ultramafic. The results showed that as much as 38% of the total potassium in the rock was released in the medium with the yeast during a 15-day period of incubation. Acid production may be the mechanism by which the yeast solubilizes potassium because the total acidity increased during the sampling period. Agitation (which increased oxygen availability) resulted in approximately 20% more biosolubilization of the alkaline ultramafic rock than with the static culture. These data indicate the potential for this yeast in biosolubilization processes and biofertilizer production.

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

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Six zoeal stages and the megalopa of the comestible crab Ucides cordatus cordatus (Linnaeus, 1763) are described and illustrated. The larvae were reared in the laboratory at temperature 25 ± 1ºC and water salinity of 24 ; duration of stages and survival rates were measured. Comparisons with the descriptions of the zoeal morphologic characters of Ocypodidae and Gecarcinidae permited to include definitively U. c. cordatus in the family Ocypodidae, subfamily Ocypodinae.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The developmental stages of Dardanus insignis (Saussure, 1858) from first through eighth zoea and megalopa are described and illuslraled. The experiments were carried out involving 100 larvae, obtained from ovigerous females collected on the north littoral of the state of São Paulo, Brazil. The larvae were kept in individual containers, with water of 34 salinity and fed with freshly hatched nauplii of Artemia; room temperature was maintained at 25±1ºC. The larval characters of this species are compared with Dardanus arrosor (Herbst, 1796). the only species of the genus that has also heen reared in laboratory.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)