978 resultados para REE mineralization
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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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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Pós-graduação em Odontologia Restauradora - ICT
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Pós-graduação em Ciência Odontólogica - FOA
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Eucalyptus plantations have seldom responded to N fertilization in tropical and subtropical regions of Brazil. This implies that rates of N mineralization have been adequate to supply tree needs. However, subsequent crop rotations with low N fertilization may result in declining concentrations of organic and potentially mineralizable N (N-0), and consequent loss of wood productivity. This study investigated (a) in situ N mineralization and N-0 in soils of eucalypt plantations in Sao Paulo state, Brazil; (b) tree growth responses to N fertilizer applied 6-18 months after planting; and (c) the relationships between N-0,N- other soil attributes and tree growth. We established eleven N fertilizer trials (maximum 240 kg ha(-1) of N) in E. grandis and E. grandis x urophylla plantations. The soil types at most sites were Oxisols and Quartzipsamments, with a range of organic matter (18 to 55 g kg(-1)) and clay contents (8% to 67%) in the 0-20 cm layer. Concentrations of N-0 were measured using anaerobic incubation on soil samples collected every three months (different seasons). The samples collected in spring and summer had N-0 140-400 kg ha(-1) (10%-19% total soil N), which were best correlated with soil texture and organic matter content. Rates of in situ net N mineralization (0-20 cm) ranged from 100 to 200 kg ha(-1) year(-1) and were not correlated with clay, total N, or N-0. These high N mineralization rates resulted in a low response to N fertilizer application during the early ages of stand growth, which were highest on sandy soils. At the end of the crop rotation, the response to N fertilizer was negligible and non-significant at all sites.
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Objectives: This report highlights phytoconstituents present in Cissus quadrangularis (CQ) extract and examines biphasic (proliferative and anti-proliferative) effects of its extract on bone cell proliferation, differentiation, mineralization, ROS generation, cell cycle progression and Runx2 gene expression in primary rat osteoblasts. Materials and methods: Phytoconstituents were identified using gas chromatography-mass spectroscopy (GC-MS). Osteoblasts were exposed to different concentrations (10-100g/ml) of CQ extract and cell proliferation and cell differentiation were investigated at different periods of time. Subsequently, intracellular ROS intensity, apoptosis and matrix mineralization of osteoblasts were evaluated. We performed flow cytometry for DNA content and real-time PCR for Runx2 gene expression analysis.Results: CQ extract's approximately 40 bioactive compounds of fatty acids, hydrocarbons, vitamins and steroidal derivatives were identified. Osteoblasts exposed to varying concentrations of extract exhibited biphasic variation in cell proliferation and differentiation as a function of dose and time. Moreover, lower concentrations (10-50g/ml) of extract slightly reduced ROS intensity, although they enhanced matrix mineralization, DNA content in S phase of the cell cycle, and levels of Runx2 expression. However, higher concentrations (75-100g/ml) considerably induced the ROS intensity and nuclear condensation in osteoblasts, while it reduced mineralization level, proportion of cells in S phase and Runx2 level of the osteogenic gene.Conclusions: These findings suggest that CQ extract revealed concentration-dependent biphasic effects, which would contribute notably to future assessment of pre-clinical efficacy and safety studies.
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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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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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The use of amoxicillin during early childhood has been associated with molar incisor hypomineralization. The objective of this study was to determine whether the use of amoxicillin interferes with enamel development, during secretion and early mineralization stages. Fifteen pregnant rats were randomly assigned to three groups that received physiological solution (sham group), 100 mg/kg/day amoxicillin (A100G), and 500 mg/kg/day amoxicillin (A500G). After birth, the pups in each group received the same treatment until post-natal day 7 or 12. The upper first molars were analyzed histomorphometrical and immunostaining with amelogenin on day 7, and MMP-20 on day 12 was performed using a semiquantitative method (H-score). At 7 days, several vacuolar structures were observed in the ameloblasts in the A100G and A500G groups. A significant reduction of the enamel thickness (P < 0.001) was found in amoxicillin-treated rats compared with the sham group. Significant differences were not observed in enamel thickness (P > 0.05) between the groups of 12-day-old rats. Moreover, significant differences were not observed in the number of amelogenin- and MMP-20-immunolabeled ameloblasts (P > 0.05) between groups. The present results suggest that amoxicillin interferes with the initial stages of amelogenesis by causing structural changes in the ameloblasts and a reduction of the enamel matrix.
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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)