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81.
Fernanda Melo Carneiro Luis Mauricio Bini Luzia Cleide Rodrigues 《Ecological Indicators》2010,10(2):249-255
From December 2003 to November 2005, we analyzed the phytoplankton community of four streams located in Central Brazil (Goiás State) to evaluate if the temporal changes in phytoplankton community structure were dependent on the taxonomic/numerical resolution used to represent the data. Classification based on functional criteria was also contrasted with taxonomic classification to assess whether these classification schemes produce different ordination patterns. Procrustean analyses indicated that ordination patterns generated with data based on the presence or absence of genera correlated significantly with the patterns generated by species density. Temporal trajectories of scores derived from functional groups significantly matched those derived from analyses based on quantitative data (density or biovolume) for genus or family. In general, the results indicated that some simplifications are justifiable, mainly when one takes into account the need for uninterrupted biomonitoring programs over large spatial scales in a continent-sized country with increasing environmental problems and with a relative paucity of scientists. 相似文献
82.
Leal LK Costa MF Pitombeira M Barroso VM Silveira ER Canuto KM Viana GS 《Life sciences》2006,79(1):98-104
The present study examines possible mechanisms by which the flavonoid isokaempferide (IKPF; 5,7,4'-trihydroxy-3-methoxyflavone) from Amburana cearensis, a Brazilian medicinal plant popularly used as bronchodilator, induces relaxation of guinea-pig isolated trachea. In the trachea (with intact epithelium) contracted by carbachol, IKPF (1-1000 microM) caused a graded relaxation, and the epithelium removal increased the sensitivity of the airway smooth muscle to IKPF (EC50, in intact tissue: 77.4 [54.8-109.2] microM; in denuded epithelium: 15.0 [11.3-20.1] microM). The IKPF-induced relaxation was inhibited in 41% by the nitric oxide (NO) synthase inhibitor L-NAME (100 microM); in 31% and 50% by the soluble guanylate cyclase (sGC) inhibitor ODQ (3 and 33 microM); by propranolol (31%) and also by capsaicin (37%). In the trachea pre-contracted by 40 mM KCl the pre-incubation with glibenclamide (33 microM) or iberiotoxin (IbTX, 0.1 microM), selective K(+) channel inhibitors, inhibited the IKPF-induced relaxation by 39% and 38%, respectively. On the other hand, 4-aminopyridine (100 microM), a nonselective K(+) channel antagonist, did not significantly influence the effect of IKPF, while IbTX induced a rightward displacement of the IKPF concentration-response curve. However, in muscle pre-contracted with 120 mM KCl the relaxant effect of IKPF was significantly reduced and not affected by glibenclamide. In conclusion, these results indicate a direct and epithelium-independent relaxant effect of IKPF on smooth muscle fibers. Although this IKPF relaxant action seems to be multi-mediated, it occurs via both Ca(2+) and ATP-sensitive K(+) channels, but some other possible mechanisms unrelated to K(+) channels cannot be excluded. 相似文献
83.
Macoris SA Sugizaki MF Peraçoli MT Bosco SM Hebeler-Barbosa F Simões LB Theodoro RC Trinca LA Bagagli E 《Memórias do Instituto Oswaldo Cruz》2006,101(3):331-334
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis, the most important systemic mycosis in Latin America. The virulence profiles of five isolates of P. brasiliensis were studied in two different moments and correlated with some colonial phenotypic aspects. We observed a significant decrease in the virulence and an intense phenotypic variation in the mycelial colony. The recognition of all ranges of phenotypic and virulence variation of P. brasiliensis, as well as its physiological and genetic basis, will be important for a better comprehension of its pathogenic and epidemiological features. 相似文献
84.
Medina JA Netto TL Muszkat M Medina AC Botter D Orbetelli R Scaramuzza LF Sinnes EG Vilela M Miranda MC 《Attention deficit and hyperactivity disorders》2010,2(1):49-58
Attention deficit hyperactivity disorder (ADHD) is related to a deficiency of central catecholamines (CA) in cognitive, biochemical, and physical tests, and pharmaceutical intervention may have no effect if it is not accompanied by changes in the environment. The objective of our study was to test the hypothesis that central CA are responsible for the increase in speed reaction seen after physical activity (PA) and to measure the impact of high intensity PA on the sustained attention of 25 children diagnosed with ADHD consistent with the Disease Statistical Mental-IV (DSM-IV) criteria. It is possible that practicing sports assists in the management of the disorder. The children were divided between users (US) and non-users (NUS) of methylphenidate (MTP), and the groups were compared to evaluate the effect of the drug on cognition after PA. Post-exercise performance on Conner's Continuous Performance Test-II (CPT) was not affected by MTP, we observed significant improvements in response time, and we saw normalization in the impulsivity and vigilance measures. These results suggest that the improvements in cognition after physical effort are not CA dependent. Additionally, our results suggest that children's attention deficits can be minimized through PA irrespective of treatment with MTP. Additional studies are necessary to confirm that exercise mitigates the harmful symptoms of ADHD. 相似文献
85.
86.
Ribeiro RS Ladeira L Rezende AM Fontes CJ Carvalho LH Brito CF 《Memórias do Instituto Oswaldo Cruz》2011,106(Z1):27-33
Reliable molecular markers are essential for a better understanding of the molecular epidemiology of Plasmodium vivax, which is a neglected human malaria parasite. The aim of this study was to analyze the genetic diversity of P. vivax isolates from the Brazilian Amazon using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the highly polymorphic merozoite surface protein-3alpha (PvMSP-3α) gene. To accomplish this, 60 isolates of P. vivax from different endemic areas in the Brazilian Amazon were collected. The PvMSP-3α gene was amplified by nested-PCR. Three major types of the PvMSP-3α locus were detected at different frequencies: type A (68%), B (15%) and C (17%). A single sample showed two PCR fragments, which corresponded to infection with types A and C. PCR-RFLP analysis using the HhaI restriction enzyme for 52 isolates clearly identified 11 haplotypes, eight of which were from type A, two from type B and only one from type C. Seven other isolates did not show a clear pattern using PCR-RFLP. This result might be due to multiple clone infections. This study showed a high diversity of the PvMSP-3α gene among P. vivax isolates from the Brazilian Amazon, but also indicated that the detection performance of PCR-RFLP of the PvMSP-3α gene may not be sufficient to detect multiple clone infections. 相似文献
87.
Paulo A. Silva Gustavo Monnerat-Cahli Amaury Pereira-Acácio Ricardo Luzardo Luzia S. Sampaio Marcia A. Luna-Leite Lucienne S. Lara Marcelo Einicker-Lamas Rogério Panizzutti Caroline Madeira Leucio D. Vieira-Filho Carmen Castro-Chaves Valdilene S. Ribeiro Ana D. O. Paix?o Emiliano Medei Adalberto Vieyra 《PloS one》2014,9(7)
Background
Several studies have correlated protein restriction associated with other nutritional deficiencies with the development of cardiovascular and renal diseases. The driving hypothesis for this study was that Ang II signaling pathways in the heart and kidney are affected by chronic protein, mineral and vitamin restriction.Methodology/Principal Findings
Wistar rats aged 90 days were fed from weaning with either a control or a deficient diet that mimics those used in impoverished regions worldwide. Such restriction simultaneously increased ouabain-insensitive Na+-ATPase and decreased (Na++K+)ATPase activity in the same proportion in cardiomyocytes and proximal tubule cells. Type 1 angiotensin II receptor (AT1R) was downregulated by that restriction in both organs, whereas AT2R decreased only in the kidney. The PKC/PKA ratio increased in both tissues and returned to normal values in rats receiving Losartan daily from weaning. Inhibition of the MAPK pathway restored Na+-ATPase activity in both organs. The undernourished rats presented expanded plasma volume, increased heart rate, cardiac hypertrophy, and elevated systolic pressure, which also returned to control levels with Losartan. Such restriction led to electrical cardiac remodeling represented by prolonged ventricular repolarization parameters, induced triggered activity, early after-depolarization and delayed after-depolarization, which were also prevented by Losartan.Conclusion/Significance
The mechanisms responsible for these alterations are underpinned by an imbalance in the PKC- and PKA-mediated pathways, with participation of angiotensin receptors and by activation of the MAPK/ERK1/2 pathway. These cellular and molecular alterations culminate in cardiac electric remodeling and in the onset of hypertension in adulthood. 相似文献88.
Constantin RP Constantin J Pagadigorria CL Ishii-Iwamoto EL Bracht A de Castro CV Yamamoto NS 《Journal of biochemical and molecular toxicology》2011,25(2):117-126
Flavonols, which possess the B-catechol ring, as quercetin, are capable of producing o-hemiquinones and to oxidize NADH in a variety of mammalian cells. The purpose of this study was to investigate whether fisetin affects the liver energy metabolism and the mitochondrial NADH to NAD+ ratio. The action of fisetin on hepatic energy metabolism was investigated in the perfused rat liver and isolated mitochondria. In isolated mitochondria, fisetin decreased the respiratory control and ADP/O ratios with the substrates α-ketoglutarate and succinate. In the presence of ADP, respiration of isolated mitochondria was inhibited with both substrates, indicating an inhibitory action on the ATP-synthase. The stimulation of the ATPase activity of coupled mitochondria and the inhibition of NADH-oxidase activity pointed toward a possible uncoupling action and the interference of fisetin with mitochondrial energy transduction mechanisms. In livers from fasted rats, fisetin inhibited ketogenesis from endogenous sources. The β-hydroxybutyrate/ acetoacetate ratio, which reflects the mitochondrial NADH/NAD+ redox ratio, was also decreased. In addition, fisetin (200 μM) increased the production of (14)CO2 from exogenous oleate. The results of this investigation suggest that fisetin causes a shift in the mitochondrial redox potential toward a more oxidized state with a clear predominance of its prooxidant activity. 相似文献
89.
The dependence of Plasmodium vivax on invasion mediated by Duffy binding protein (DBP) makes this protein a prime candidate for development of a vaccine. However, the development of a DBP-based vaccine might be hampered by the high variability of the protein ligand (DBP(II)), known to bias the immune response toward a specific DBP variant. Here, the hypothesis being investigated is that the analysis of the worldwide DBP(II) sequences will allow us to determine the minimum number of haplotypes (MNH) to be included in a DBP-based vaccine of broad coverage. For that, all DBP(II) sequences available were compiled and MNH was based on the most frequent nonsynonymous single nucleotide polymorphisms, the majority mapped on B and T cell epitopes. A preliminary analysis of DBP(II) genetic diversity from eight malaria-endemic countries estimated that a number between two to six DBP haplotypes (17 in total) would target at least 50% of parasite population circulating in each endemic region. Aiming to avoid region-specific haplotypes, we next analyzed the MNH that broadly cover worldwide parasite population. The results demonstrated that seven haplotypes would be required to cover around 60% of DBP(II) sequences available. Trying to validate these selected haplotypes per country, we found that five out of the eight countries will be covered by the MNH (67% of parasite populations, range 48-84%). In addition, to identify related subgroups of DBP(II) sequences we used a Bayesian clustering algorithm. The algorithm grouped all DBP(II) sequences in six populations that were independent of geographic origin, with ancestral populations present in different proportions in each country. In conclusion, in this first attempt to undertake a global analysis about DBP(II) variability, the results suggest that the development of DBP-based vaccine should consider multi-haplotype strategies; otherwise a putative P. vivax vaccine may not target some parasite populations. 相似文献
90.