915 resultados para Tubule Morphogenesis
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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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ABSTRACT. Introduction: an in vitro model was used to measure the hydraulic conductance in human dentin discs treated with oxalic acid for 15, 30 or 60 s maintaining the occlusive effect and measuring 7 and 14 days after application. Methods: 45 dentin discs measuring 1 mm thick were obtained from human third molars which were free of caries and in no occlusion; the samples were obtained from patients aged 16 to 30 years. Discs were sorted out into three study groups (n = 15) depending on the time of application of a commercial solution of oxalate-based dentin desensitizer (DD) (BisBlock®) which contains ˂ 5% oxalic acid of 1.5-1.8 pH: in group A the agent was applied for 15 s, in group B it was applied for 30 s, and in group C for 60 s. The hydraulic conductance of each disc was calculated after acid etching, which corresponds to the maximum permeability of discs (100%) after immediate application of oxalic acid, as well as seven and fourteen days of storage in saline solution. The statistical analysis was done with ANOVA test and post-hoc Games-Howell test. Results: 35,46 ± 23.41% in Group A, 36.34 ± 15.88% in Group B and 24.99 ± 14.99% in Group C, showing that the use of DD for 15, 30 or 60 s decreased permeability in a statistically significant manner (p <0.05). Conclusions: DD was effective in reducing hydraulic conductance regardless of application time, but this reduction was temporary only, since after seven days permeability returns to values close to those of baseline.
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV
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Pós-graduação em Odontologia Restauradora - ICT
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Objective of this work by evaluating the effect of nitrogen on forage yield and morphogenesis of elephant grass cv. Pioneer. The experimental design was randomized blocks with five replications, totaling 20 experimental units. Treatments consisted of four nitrogen levels (100, 200, 300 and 400 kg ha(-1) yr(-1)). The experiment was conducted under irrigated conditions. Evaluative cuts were made at 50 cm soil with values of light interception (95%) without pre-defined intervals. It was observed that N fertilization increased significantly (P<0.05) the production of dry matter per hectare, leaf appearance rate (leaves days(-1)tiller(-1)), leaf elongation rate (cm tiller(-1) day(-1)) and stem elongation rate (cm day(-1)). The process of this forage senescence is accelerated with increasing doses of nitrogen and leaf appearance rate, thereby reducing the phyllochron. It required a study on the economic viability of higher doses of nitrogen in grazed elephant grass cv. Pioneer.
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The objective of this study was to evaluate the rate of leaf appearance, leaf elongation rate, number of green leaves, length of blade and stem of Brachiaria brizantha cv. Marandu under different nitrogen levels and two residue heights. A randomized block design was used in a 4 x 2 factorial scheme, four doses of nitrogen (100, 200, 300 and 400 kg N ha(-1) year(-1)) and two residue heights (5 and 15 cm). There was significant interaction between residue height and nitrogen levels for leaf appearance rate of signal grass, which was influenced negatively and linearly by the residue heights being observed an average reduction of 28.20% from lower to higher residue. There was no interaction between the levels of nitrogen x residue height on the number of green leaves. The dosage that provided the highest stalk in the residue height of 5 cm was of 271.5 kg N ha(-1). An increase of 0.0745 cm tiller(-1) day(-1) for 1 kg of N ha(-1) applied to height of 15 cm of residue was observed. Nitrogen fertilization contributes positively to growth and development of rates of appearance and leaf extension. The management of pasture of Brachiaria brizantha cv. Marandu with 5 cm of residue and fertilization with 100 kg N ha(-1) provided better answer morphogenic traits.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Although there are several studies on morphogenesis in Teleostei, until now there is no research describing the role of the basement membrane in the establishment of the germinal epithelium during gonadal differentiation in Characiformes. In attempt to study these events that result in the formation of ovarian and testicular structures, gonads of Gymnocorymbus ternetzi were prepared for light microscopy. During gonadal development in G. ternetzi, all individuals first developed ovarian tissue. The undifferentiated gonad was formed by somatic cells (SC) and primordial germ cells (PGCs). After successive mitosis, the PGCs became oogonia, which entered into meiosis originating oocytes. An interstitial tissue developed. In half of the individuals, presumptive female, prefollicle cells synthesized a basement membrane around oocyte forming a follicle. Along the ventral region of the ovary, the tissue invaginated to form the ovigerous lamellae, bordered by the germinal epithelium. Stroma developed and the follicle complexes were formed. The gonadal aromatase was detected in interstitial cells in the early steps of the gonadal differentiation in both sexes. In another half of the individuals, presumptive male, there was no synthesis of basement membrane. The interstitium was invaded by numerous granulocytes. Pre-Leydig cells proliferated. Apoptotic oocytes were observed and afterward degenerated. Spermatogonia appeared near the degenerating oocytes and associated to SCs, forming testicular tubules. Germinal epithelium developed and the basement membrane was synthesized. Concomitantly, there was decrease of the gonadal aromatase and increase in the 3β-HSD enzyme expression. Thus, the testis was organized on an ovary previously developed, constituting an indirect gonochoristic differentiation.
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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 Tecnol[ogico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties of tissue for potential preventive or reparative therapies. The objectives of the study were to systematically characterize dentin matrices biomodified by proanthocyanidin-rich grape seed extract (GSE) and glutaraldehyde (GD). Changes to the biochemistry and biomechanical properties were assessed by several assays to investigate the degree of interaction, biodegradation rates, proteoglycan interaction, and effect of collagen fibril orientation and environmental conditions on the tensile properties. The highest degree of agent–dentin interaction was observed with GSE, which exhibited the highest denaturation temperature, regardless of the agent concentration. Biodegradation rates decreased remarkably following biomodification of dentin matrices after 24 h collagenase digestion. A significant decrease in the proteoglycan content of GSE-treated samples was observed using a micro-assay for glycosaminoglycans and histological electron microscopy, while no changes were observed for GD and the control. The tensile strength properties of GD-biomodified dentin matrices were affected by dentin tubule orientation, most likely due to the orientation of the collagen fibrils. Higher and/or increased stability of the tensile properties of GD- and GSE-treated samples were observed following exposure to collagenase and 8 months water storage. Biomodification of dentin matrices using chemical agents not only affects the collagen biochemistry, but also involves interaction with proteoglycans. Tissue biomodifiers interact differently with dentin matrices and may provide the tissue with enhanced preventive and restorative/reparative abilities.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)