Animal performance and nutritional characteristics of Piatã-grass in integrated systems / Desempenho animal e características nutricionais de capim-piatã em sistemas integrados

The objective was to evaluate animal performance and nutritional characteristics of Brachiaria brizantha cv. BRS Piatã in two integrated systems, during the summer and winter, five years after the initial establishment of the area. The randomized block experimental design was adopted with treatments consisting of a control (five native trees per hectare) and an integrated crop-livestock-forestry (ICLF) system with 227 eucalyptus trees per hectare. Animal performance, canopy height, soil cover, forage mass (leaf, stem and senescent material), and forage nutritive value were evaluated. Differences between systems were observed in forage mass (total, leaf, stem and senescent material), soil cover and forage nutritive value in both seasons. Shading conditions provided by eucalyptus in the ICLF system lead to a reduction in forage mass and neutral detergent fiber content, and to an increase in crude protein and in vitro organic matter digestibility. However, no effect on animal performance was obtained. The presence of trees improves the forage nutritive value without impacting animal performance in integrated systems.(AU)

O objetivo foi avaliar o desempenho animal e as características nutricionais de Brachiaria brizantha cv. BRS Piatã em dois sistemas integrados, durante o verão e o inverno, cinco anos após o estabelecimento inicial da área. O delineamento experimental em blocos ao acaso foi adotado com tratamentos constituídos por um controle (cinco árvores nativas por hectare) e um sistema integrado lavoura-pecuária-floresta (ILPF) com 227 eucaliptos por hectare. Desempenho animal, altura do dossel, cobertura do solo, massa de forragem (folha, caule e material senescente) e valor nutritivo da forragem foram avaliados. Diferenças entre os sistemas foram observadas na massa de forragem (total, foliar, caule e material senescente), na cobertura do solo e no valor nutritivo da forragem em ambas as estações. As condições de sombreamento proporcionadas pelo eucalipto no sistema ICLF levaram a uma redução na massa de forragem e no teor de fibra em detergente neutro e a um aumento na proteína bruta e na digestibilidade in vitro da matéria orgânica. No entanto, nenhum efeito no desempenho animal foi obtido. A presença de árvores melhora o valor nutritivo da forragem, sem impactar o desempenho animal em sistemas integrados.(AU)

Expression of genes associated with the biosynthetic pathways of abscisic acid, gibberellin, and ethylene during the germination of lettuce seeds.

Seed germination and dormancy are complex phenomena that are controlled by many genes and environmental factors. Such genes are indicated by phytohormones that interact with each other, and may cause dormancy or promote seed germination. The objective of this study was to investigate gene expression associated with the biosynthetic pathways of abscisic acid (ABA), gibberellic acid (GA), and ethylene (ET) in dormant and germinated lettuce seeds. The expressions of LsNCED, LsGA3ox1, and ACO-B were evaluated in germinating and dormant seeds from the cultivars Everglades, Babá de Verão, Verônica, Salinas, Colorado, and Regina 71. The expressions of LsNCED, LsGA3ox1, and ACO-B were related to the biosynthesis of ABA, GA, and ET, respectively; therefore, the presence of these substances depends on genotype. LsNCED expression only occurred in dormant seeds, and was connected to dormancy. LsGA3ox1expression only occurred in germinated seeds, and was connected to germination. The ACO-B gene was involved in ET biosynthesis, and was expressed differently in germinated and dormant seeds, depending on the genotype, indicating different functions for different characteristics. Furthermore, sensitivity to phytohormones appeared to be more important than the expression levels of LsNCED, LsGA3ox1, or ACO-B.

The effect of the surface functionalization and the electrolyte concentration on the electrical conductance of silica nanochannels.

It is known that the conductance of nanochannels as a function of electrolyte concentration deviates from a linearly proportional relationship and approaches a value independent of the concentration as the electrolyte concentration is lowered. Most of the proposed models account for this behavior by considering a constant surface charge density and an ideal electrolyte solution. However, at low electrolyte concentrations, the ideal electrolyte approximation is no longer valid because the ions that result from the atmospheric carbon dioxide dissolution in water dominate the ionic concentration. In this paper, arrays of silica nanochannels were electrically characterized via conductance measurements. The conductance at low salt concentrations is modeled by a variable surface charge model that accounts for all ionic species in solution. This model was used to determine the variable surface charge of the bare silica nanochannels as well as of chemically modified nanochannels. The model correctly predicted the variation of the nanochannel conductance observed after silane (aminopropyldimethylethoxysilane) functionalization and single-strand DNA immobilization. Finally, pH modification of bulk KCl solutions was employed as an alternative method of changing the surface charge of silica nanochannels. Surface charge calculated from conductance measurements performed at different bulk pH values confirmed that the surface charge of the silica nanochannel walls is sensitive to the H(+) concentration.

Temporal cortex direct current stimulation enhances performance on a visual recognition memory task in Alzheimer disease.

Several studies have reported that transcranial direct current stimulation (tDCS), a non-invasive method of neuromodulation, enhances some aspects of working memory in healthy and Parkinson disease subjects. The aim of this study was to investigate the impact of anodal tDCS on recognition memory, working memory and selective attention in Alzheimer disease (AD). Ten patients with diagnosis of AD received three sessions of anodal tDCS (left dorsolateral prefrontal cortex, left temporal cortex and sham stimulation) with an intensity of 2 mA for 30 min. Sessions were performed in different days in a randomised order. The following tests were assessed during stimulation: Stroop, Digit Span and a Visual Recognition Memory task (VRM). The results showed a significant effect of stimulation condition on VRM (p = 0.0085), and post hoc analysis showed an improvement after temporal (p = 0.01) and prefrontal (p = 0.01) tDCS as compared with sham stimulation. There were no significant changes in attention as indexed by Stroop task performance. As far as is known, this is the first trial showing that tDCS can enhance a component of recognition memory. The potential mechanisms of action and the implications of these results are discussed.

[Fraction of gemistocytic astrocytes and immunoexpression of p53 protein in astrocytomas grade II and III (WHO)]. / Indice de astrócitos gemistocíticos e imuno-expressão da proteína p53 em astrocitomas, grau II e III OMS.

Twenty-two patients with astrocytomas, grade II or III WHO, were studied from 1990 to 1998. In all cases, histopathology showed that the astrocytomas had a gemistocytic component. The aims of this study were to establish the fraction of gemistocytic astrocytes, to investigate p53 protein immunoexpression and to evaluate correlations between these two parameters with the tumour outcome. Tumor cells were quantified at high-power magnification (x400). At least 1000 neoplastic cells (small neoplastic astrocytes plus gemistocytes) were counted in each specimen. The percentage of gemistocytes was defined as the gemistocytic index. Nuclear expression of p53 protein was evaluated in neoplastic astrocytes and gemistocytes. Both the frequency (7/22) as well the p53 immunoexpression indices in gemistocytes, regardless of the grade of the astrocytomas, were inferior from those reported in the literature. No correlation was found between the gemistocytic indices and the p53 immunoexpression.

Ca(2+)/nicotinamide adenine dinucleotide phosphate-dependent H(2)O(2) generation is inhibited by iodide in human thyroids.

A calcium and NAD(P)H-dependent H(2)O(2)-generating activity has been studied in paranodular thyroid tissues from four patients with cold thyroid nodules and from nine diffuse toxic goiters. H(2)O(2) generation was detected both in the particulate (P 3,000 g) and in the microsomal (P 100,000 g) fractions of paranodular tissue surrounding cold thyroid nodules (PN), with the same biochemical properties described for NADPH oxidase found in porcine and human thyroids. In PN tissues, the particulate NADPH oxidase activity (224 +/- 38 nmol H(2)O(2) x h(-1) x mg(-1) protein) was similar to that described for the porcine thyroid enzyme. However, no NADPH oxidase activity was detectable in the particulate fractions from eight diffuse toxic goiter patients treated with iodine before surgery; all but one also received propylthiouracil or methimazole in the preoperative period. Thyroid cytochrome c reductase (diffuse toxic goiters = 438 +/- 104 nmol NADP(+) x h(-1) x mg(-1) protein; PN = 78 +/- 10 nmol NADP(+) x h(-1) x mg(-1) protein) and thyroperoxidase (diffuse toxic goiters = 621 +/- 179 U x g(-1) protein; PN = 232 +/- 121 U x g(-1) protein) activities were unaffected by iodide. Thus, the human NADPH oxidase seems to be inhibited by iodinated compounds in vivo and probably is an enzyme involved in the Wolff-Chaikoff effect. Our findings reinforce the hypothesis that thyroid NADPH oxidase is responsible for the production of H(2)O(2) necessary for thyroid hormone biosynthesis.

Dilated cardiomyopathy in two transgenic mouse lines expressing activated G protein alpha(q): lack of correlation between phospholipase C activation and the phenotype.

We previously described a transgenic mouse line (alpha(q)*52) in which cardiac-specific expression of activated G alpha(q)protein (HA alpha(q)*) leads to activation of phospholipase C beta (PLC beta), the immediate downstream target of HA alpha(q)*, with subsequent development of cardiac hypertrophy and dilation. We now describe a second, independent line in the same genetic background (alpha(q)*44h) with lower expression of HA alpha(q)* protein that ultimately results in the same phenotype: dilated cardiomyopathy (DCM) with severely impaired left ventricular systolic function (assessed by M-mode and 2D echocardiography), but with a much delayed disease onset. We asked if PLC activation correlates with the development of the phenotype. At 12-14 months, 65% of alpha(q)*44h mice still had normal cardiac function and ventricular weight/body weight ratios (VW/BW). However, their basal PLC activity, which began to increase in ventricles at 6 months, was threefold higher than in wild-type by 12 months. This increase was even more pronounced than in 2.5-month-old alpha(q)*52 mice, in which a twofold increase was accompanied by a 25% increase in VW/BW. Furthermore, at 12-14 months the increase in PLC activity in alpha(q)*44h mice with and without DCM was comparable. Thus, the delayed time course in alpha(q)*44h mice unmasked a lack of correlation between PLC activation and development of DCM in response to HA alpha(q)* expression, suggesting a role for additional pathways and/or mechanisms. It also revealed a differential temporal regulation of protein kinase C isoform expression. The markedly different ages of disease onset in these two mouse lines provide a model for studying both genetic modifying factors and potential environmental influences in DCM.