RCAAP - Repositório Científico de Acesso Aberto de Portugal
Not a member yet
513596 research outputs found
Sort by
Síntese de estruturas do tipo endo-exo dodecanos com substituintes em diferentes posições na molécula
No full textMicrotexturas do ouro nativo e sulfetos do depósito Ogó, Greenstone belt Pilar de Goiás, Goiás
No full text
Vitamin D deficiency in girls from South Brazil : a cross-sectional study on prevalence and association with vitamin D receptor gene variants
No full textBackground: Vitamin D deficiency has been associated with a multitude of disorders including diabetes, defective insulin secretion as well as rickets and poor bone health. Vitamin D is also a concern during childhood and adolescence and has been reported in girls from South Brazil. We determined the prevalence of vitamin D deficiency in girls from South Brazil and investigated whether the genotypic distribution of the BsmI, ApaI and TaqI polymorphisms of the VDR gene and their haplotypes were associated with vitamin D levels. Methods: Cross-sectional study including 234 apparently healthy girls aged 7 to 18 years. Height and weight were measured for calculation of body mass index (BMI) percentiles for age. Plasma levels of 25-hydroxyvitamin D [25(OH)D] were assessed. Participants were genotyped for ApaI (rs7975232), TaqI (rs731236), and BsmI (rs1544410) SNPs. Results: The median and interquartile range (25-75%) of BMI percentile was 62.0 (33.3 – 84.9). The frequency of overweight/obesity was 24.9%. Circulating levels of 25(OH)D (≥ 30 ng/mL) were adequate in 9.4%; insufficient in 54.3% (20–29 ng/mL); and deficient in 36.3% (< 20 ng/mL). Genotype frequencies were GG = 47.0%, GA = 41.5%, and AA = 11.5% for BsmI; GG = 16.7%, GT = 52.6%, and TT = 30.8% for ApaI; TT = 46.2%, TC = 44.9% and CC = 9.0% for TaqI. Genotypes with no gene variance (ancestral wild genotype) of BsmI (GG vs. GA + AA, two-tailed Student’s t-test p<0.001), ApaI (GG vs. GT + TT, two-tailed Student’s t-test p = 0.031) and TaqI (TT vs. TC + CC, two-tailed Student’s t-test p = 0.005) SNPs and the GGT haplotype (two-tailed Student’s t-test p = 0.036) were significantly associated with lower 25(OH)D levels. Conclusions: 25-hydroxyvitamin D deficiency and insufficiency were highly prevalent in this sample. The BsmI, ApaI and TaqI wild variants of the VDR gene, as well as the GGT haplotype, were associated with lower vitamin D levels, suggesting that VDR gene polymorphisms could be linked to higher susceptibility to vitamin D deficiency in a sub-population of children and adolescents
Meta-analyses and Forest plots using a microsoft excel spreadsheet: step-by-step guide focusing on descriptive data analysis
No full textBackground: Meta-analyses are necessary to synthesize data obtained from primary research, and in many situations reviews of observational studies are the only available alternative. General purpose statistical packages can meta-analyze data, but usually require external macros or coding. Commercial specialist software is available, but may be expensive and focused in a particular type of primary data. Most available softwares have limitations in dealing with descriptive data, and the graphical display of summary statistics such as incidence and prevalence is unsatisfactory. Analyses can be conducted using Microsoft Excel, but there was no previous guide available. Findings: We constructed a step-by-step guide to perform a meta-analysis in a Microsoft Excel spreadsheet, using either fixed-effect or random-effects models. We have also developed a second spreadsheet capable of producing customized forest plots. Conclusions: It is possible to conduct a meta-analysis using only Microsoft Excel. More important, to our knowledge this is the first description of a method for producing a statistically adequate but graphically appealing forest plot summarizing descriptive data, using widely available software
Efeito da desnervação renal sobre a pressão arterial e a sensibilidade do reflexo pressorreceptor em animais normotensos
No full textLipopolysaccharide modulates astrocytic S100B secretion: a study in cerebrospinal fluid and astrocyte cultures from rats
No full textBackground: Inflammatory responses in brain are primarily mediated by microglia, but growing evidence suggests a crucial importance of astrocytes. S100B, a calcium-binding protein secreted by astrocytes, has properties of a neurotrophic or an inflammatory cytokine. However, it is not known whether primary signals occurring during induction of an inflammatory response (e.g. lipopolysaccharide, LPS) directly modulate S100B. Methods: In this work, we evaluated whether S100B levels in cerebrospinal fluid (CSF) and serum of Wistar rats are affected by LPS administered by intraperitoneal (IP) or intracerebroventricular (ICV) injection, as well as whether primary astrocyte cultures respond directly to lipopolysaccharide. Results: Our data suggest that S100B secretion in brain tissue is stimulated rapidly and persistently (for at least 24 h) by ICV LPS administration. This increase in CSF S100B was transient when LPS was IP administered. In contrast to these S100B results, we observed an increase in in TNFa levels in serum, but not in CSF, after IP administration of LPS. In isolated astrocytes and in acute hippocampal slices, we observed a direct stimulation of S100B secretion by LPS at a concentration of 10 μg/mL. An involvement of TLR4 was confirmed by use of specific inhibitors. However, lower levels of LPS in astrocyte cultures were able to induce a decrease in S100B secretion after 24 h, without significant change in intracellular content of S100B. In addition, after 24 h exposure to LPS, we observed a decrease in astrocytic glutathione and an increase in astrocytic glial fibrillary acidic protein. Conclusions: Together, these data contribute to the understanding of the effects of LPS on astrocytes, particularly on S100B secretion, and help us to interpret cerebrospinal fluid and serum changes for this protein in neuroinflammatory diseases. Moreover, non-brain S100B-expressing tissues may be differentially regulated, since LPS administration did not lead to increased serum levels of S100B
A potential source for cellulolytic enzyme discovery and environmental aspects revealed through metagenomics of brazilian mangroves
No full textThe mangroves are among the most productive and biologically important environments. The possible presence of cellulolytic enzymes and microorganisms useful for biomass degradation as well as taxonomic and functional aspects of two Brazilian mangroves were evaluated using cultivation and metagenomic approaches. From a total of 296 microorganisms with visual differences in colony morphology and growth (including bacteria, yeast and filamentous fungus), 179 (60.5%) and 117 (39.5%) were isolated from the Rio de Janeiro (RJ) and Bahia (BA) samples, respectively. RJ metagenome showed the higher number of microbial isolates, which is consistent with its most conserved state and higher diversity. The metagenomic sequencing data showed similar predominant bacterial phyla in the BA and RJ mangroves with an abundance of Proteobacteria (57.8% and 44.6%), Firmicutes (11% and 12.3%) and Actinobacteria (8.4% and 7.5%). A higher number of enzymes involved in the degradation of polycyclic aromatic compounds were found in the BA mangrove. Specific sequences involved in the cellulolytic degradation, belonging to cellulases, hemicellulases, carbohydrate binding domains, dockerins and cohesins were identified, and it was possible to isolate cultivable fungi and bacteria related to biomass decomposition and with potential applications for the production of biofuels. These results showed that the mangroves possess all fundamental molecular tools required for building the cellulosome, which is required for the efficient degradation of cellulose material and sugar release
Geological and climatic changes in quaternary shaped the evolutionary history of Calibrachoa heterophyla, an endemic south-atlantic species of petunia
No full textBackground: The glacial and interglacial cycles that characterized the Quaternary greatly affected the distribution and genetic diversity of plants. In the Neotropics, few phylogeographic studies have focused on coastal species outside of the Atlantic Rainforest. Climatic and sea level changes during the Quaternary played an important role in the evolutionary history of many organisms found in coastal regions. To contribute to a better understanding of plant evolution in this environment in Southern South America, we focused on Calibrachoa heterophylla (Solanaceae), an endemic and vulnerable wild petunia species from the South Atlantic Coastal Plain (SACP). Results: We assessed DNA sequences from two cpDNA intergenic spacers and analyzed them using a phylogeographic approach. The present phylogeographic study reveals the influence of complex geologic and climatic events on patterns of genetic diversification. The results indicate that C. heterophylla originated inland and subsequently colonized the SACP; the data show that the inland haplogroup is more ancient than the coastal one and that the inland was not affected by sea level changes in the Quaternary. The major diversification of C. heterophylla that occurred after 0.4 Myr was linked to sea level oscillations in the Quaternary, and any diversification that occurred before this time was obscured by marine transgressions that occurred before the coastal sand barrier’s formation. Results of the Bayesian skyline plot showed a recent population expansion detected in C. heterophylla seems to be related to an increase in temperature and humidity that occurred at the beginning of the Holocene. Conclusions: The geographic clades have been formed when the coastal plain was deeply dissected by paleochannels and these correlate very well with the distributional limits of the clades. The four major sea transgressions formed a series of four sand barriers parallel to the coast that progressively increased the availability of coastal areas after the regressions and that may have promoted the geographic structuring of genetic diversity observed today. The recent population expansion for the entire species may be linked with the event of marine regression after the most recent sea transgression at ~5 kya