1,513 research outputs found

    Equilibrium states for a class of skew products

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    GRASS UTILIZATION IN GROWING FINISHING BÍSARO PIGS (85-107 KG). PERFORMANCE AND CARCASS COMPOSITION

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    The use of different quantities of vegetables, forages or fresh grass as fodder for growing-finishing pigs is an important factor of the northern Portugal traditional system. The increasing development of swine production in outdoor systems, extensive and organic production, turns to upcoming natural diets, in which grass performs a significant part. With regard to this, some investigation has been made concerning the use of fibre-rich feed ingredients in pig nutrition. Metabolic effects of its ingestion are analysed concerning different sights (economical, social, environmental and physiological ones). The aim of this work was to study the effects of grass utilization in the diets on performances of finishing Bísaro pigs. A total of 22 pigs (16 castrated males and 6 females) was housed outdoor and fed ad libitum (37 – 85 kg live weight) with a growing diet and then transferred to an indoor system (with free access to an outdoor area) for 49 days, according to 3 different treatments: 100% concentrate (C), 75% concentrate + ad libitum grass (CE75), 50% concentrate + ad libitum grass (CE50). The grass was supplied and its intake registered on a daily basis. Every 14 days, the pigs were weighted and their back fat (P2 in vivo) measured. After slaughter (average weight of 107 kg LW), yield and ½ left carcass characteristics were controlled. During the outdoor growing phase, the ADG was 513 g/day. During the indoor finishing phase, the increase grass intake was proportional to the reduction of concentrate in the diet. The ADG (g) and the fat deposition (P2 cm) were significantly different (P<0,05) in the 3 treatments (ADG: C=641, CE75=467, CE50=356 and: C=11,4, CE75=+9,5, CE50=+6,2). The empty body weight (kg) was also proportional to the intake of concentrate (C=116,2; CE75=107,7; CE50=102,2). Comparatively to the weight of the body parts, pigs that had higher intake of grass and lower of concentrate showed a higher % of shoulder (P<0,05; C=20,4, CE75=21,7, CE50=22,2) and the pH45min of CE carcasses was significantly higher (P<0,05). As a conclusion, concentrate substitution for grass showed a slower growing rate, thinner carcasses and a high technological quality. Neverthelles variability (CV %) of the productive parameters at the end of this study were higher in the treatments that included grass: live weight (C= 10,5%; C75=10,7%; C50=14,3%), finishing ADG (C=24%; C75=37%, C50=42%), and final fat (C=37%; C75=32%, C50=52%). These values suggest that the utilization of fibrous feeds in growing-finishing swine may be one of the possible explanations of the more heterogeneous products and carcasses found in the traditional or extensive systems, common users of fibrous feeds in the carcass finishing phase

    The effects of long-term chaetomellic acid a administration on renal function and oxidative stress in a rat model of renal mass reduction

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    This study aimed to evaluate the effect of chronic treatment with chaetomellic acid A (CAA) on oxidative stress and renal function in amodel of renalmass reduction. Methods.MaleWistar ratswere subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been divided into four experimental groups: RMR: RMR rats without treatment (n = 14); RMR + CAA: RMR rats treated with CAA (n = 13); SO: SO rats without treatment (n = 13); and SO + CAA: SO rats treated with CAA (n = 13). CAA was intraperitoneally administered in a dose of 0.23 μg/Kg three times a week for six months. Results. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity (p < 0.05) and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CAAadministration significantly increased catalase andGR activity (p < 0.05) and increased GSH/GSSG ratio, but no significant difference between the treated and nontreated groups was found in this ratio.No significant differences were found between theRMRgroups in any of the parameters of renal function.However, CAA administration slightly improves some parameters of renal function. Conclusions. These data suggest that CAA could attenuate 5/6 RMR-induced oxidative stress.The authors would like to thank Jos´e Miguel Lopez- Novoa for valuable comments and suggestions. This work is supported by European Investment Funds by FEDER/ COMPETE/POCI, Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145- FEDER-006958, and National Funds by FCT, Portuguese Foundation for Science and Technology, under Project UID/AGR/04033/2013, and by European Investment Funds by FEDER/COMPETE/POCI, Operational Competitiveness and Internationalization Programme, under Project POCI- 01-0145-FEDER-016728, and National Funds by FCT, Portuguese Foundation for Science and Technology, under Project PTDC/DTP-DES/6077/2014.info:eu-repo/semantics/publishedVersio

    Pathophysiological mechanisms of renal fibrosis: a review of animal models and therapeutic strategies

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    Chronic kidney disease (CKD) is a long-term condition in which the kidneys do not work correctly. It has a high prevalence and represents a serious hazard to human health and estimated to affects hundreds of millions of people. Diabetes and hypertension are the two principal causes of CKD. The progression of CKD is characterized by the loss of renal cells and their replacement by extracellular matrix (ECM), independently of the associated disease. Thus, one of the consequences of CKD is glomerulosclerosis and tubulointerstitial fibrosis caused by an imbalance between excessive synthesis and reduced breakdown of the ECM. There are many molecules and cells that are associated with progression of renal fibrosis e.g. angiotensin II (Ang II). Therefore, in order to understand the biopathology of renal fibrosis and for the evaluation of new treatments, the use of animal models is crucial such as: surgical, chemical and physical models, spontaneous models, genetic models and in vitro models. However, there are currently no effective treatments for preventing the progression of renal fibrosis. Therefore it is essential to improve our knowledge of the cellular and molecular mechanisms of the progress of renal fibrosis in order to achieve a reversion/elimination of renal fibrosis.This work was supported in part by a project grant from the Fundação para a Ciência e Tecnologia, Ministério da Educação, Portugal (grant no. SFRH/PROTEC/67576/2010).info:eu-repo/semantics/publishedVersio

    Moduli of stability for heteroclinic cycles of periodic solutions

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    We consider C2C^2 vector fields in the three dimensional sphere with an attracting heteroclinic cycle between two periodic hyperbolic solutions with real Floquet multipliers. The proper basin of this attracting set exhibits historic behavior and from the asymptotic properties of its orbits we obtain a complete set of invariants under topological conjugacy in a neighborhood of the cycle. As expected, this set contains the periods of the orbits involved in the cycle, a combination of their angular speeds, the rates of expansion and contraction in linearizing neighborhoods of them, besides information regarding the transition maps and the transition times between these neighborhoods. We conclude with an application of this result to a class of cycles obtained by the lifting of an example of R. Bowen.Comment: 23 pages, 6 figure

    The role of the saddle-foci on the structure of a Bykov attractor

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    We consider a one-parameter family ( fλ)λ 0 of symmetric vector fields on the three-dimensional sphere whose flows exhibit a heteroclinic network between two saddle-foci inside a global attracting set. More precisely, when λ = 0, there is an attracting heteroclinic cycle between the two equilibria which is made of two 1- dimensional connections together with a 2-dimensional sphere which is both the stable manifold of one saddle-focus and the unstable manifold of the other. After slightly increasing the parameter while keeping the 1-dimensional connections unaltered, the two-dimensional invariant manifolds of the equilibria become transversal, and thereby create homoclinic and heteroclinic tangles. It is known that these newborn structures are the source of a countable union of topological horseshoes, which prompt the coexistence of infinitely many sinks and saddle-type invariant sets for many values of λ. We show that, for every small enough positive parameter λ, the stable and unstable manifolds of the saddle-foci and those infinitely many horseshoes are contained in the global attracting set of fλ; moreover, the horseshoes belong to the heteroclinic class of the equilibria. In addition, we show that the set of chain-accessible points from either of the saddle-foci is chain-stable and contains the closure of the invariant manifolds of the two equilibria.info:eu-repo/semantics/publishedVersio

    Ação do ácido quetomélico nas alterações hematológicas induzidas pela redução de 5/6 de massa renal em ratos

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    A doença renal crónica está associada com o desenvolvimento de anemia devido principalmente à diminuição da produção de eritropoetina. O ácido quetomélico (AC) é um potente inibidor seletivo da farnesil transferase e, desta forma, inibe as vias de sinalização que levam à progressão da fibrose renal. Assim, o objectivo deste trabalho foi o de estudar os efeitos do tratamento crónico com o AC nas alterações hematológicas induzidas pela redução de 5/6 de massa renal (RMR). Neste estudo foram utilizados 70 ratos machos da estirpe Wistar. Uma semana após a redução cirúrgica de 5/6 de massa renal, os animais foram divididos em quatro grupos experimentais: CO: animais em que se simulou a cirurgia e sem tratamento; CO+AC: animais em que se simulou a cirurgia e tratados com o AC; RMR: animais com RMR e não tratados; RMR+AC: animais com RMR e tratados com o AC. O tratamento foi administrado por via intraperitoneal, durante seis meses. Para o estudo hematológico procedeu-se à contagem manual, em câmara de Neubauer, do número total de eritrócitos e de leucócitos, à determinação do microhematócrio, à contagem diferencial de leucócitos e à estimativa do número total de plaquetas no esfregaço de sangue corado com Diff-Quick. Nos grupos RMR e RMR+AC observou-se um aumento estatisticamente significativo (p<0.01) do número total de eritrócitos, do microhematócrito, do número total de leucócitos e das plaquetas, em relação aos grupos CO e CO+AC. Deste modo, os resultados deste estudo sugerem que em ratos Wistar com doença renal crónica, o tratamento com o AC, durante seis meses, não diminui a gravidade da anemia, da leucocitose e da trombocitose induzidas pela redução de 5/6 de massa renal

    On the width of the last scattering surface

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    We discuss the physical effects of some accelerated world models on the width of the last scattering surface (LSS) of the cosmic microwave background radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and a Chaplygin type gas. The redshift of the LSS does not depend on the kind of dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of the LSS is also only weakly dependent on the kind of scenario (if we have dark energy plus cold dark matter or the unified picture).Comment: 10 pages, 1 figure, 2 tables, accepted to IJMP
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