RESUMO
Pasture management that considers pasture growth dynamics remains an open question. Conceptually, such management must allow for grazing only after the recuperation of the pasture between two separate timely grazing periods when pasture reaches optimum recovery, as per the first law of Voisin's rational grazing system. The optimum recovery period not only implies a pasture with better nutritional value and higher biomass yield but one that also reduces the production of enteric methane (CH4) to improve the grazing efficiency of cattle. Therefore, this study aimed to evaluate three different recovery periods (RP) of mixed grasses on the grazing behaviour of heifers, as well as herbage selectivity, herbage yield and nutritional value, in vitro degradability and CH4 production. Based on these criteria, three pasture RPs of 24 (RP24), 35 (RP3) and 46 (RP46) days were evaluated in six blocks using a randomized block design. At each predetermined RP, samples of the pasture were taken before the animals were allowed to graze. Right after collecting the pasture samples, heifers accessed the pasture during 4 h consecutively for grazing simulation and behavioural observations. We also measured the bite rate of each animal. The pasture growing for 24 days had the highest biomass production, best nutritional value, best efficiency of in vitro CH4 relative emission (ml) per DM degraded (g) and bite rate of the three RPs. Heifers all selected their herbage, irrespective of RP, but with different nutritional value and higher in vitro degradability. However, this did not change the production of in vitro CH4. Considering the growth conditions of the area where the study was performed, we recommend the shorter RP24 as the most suitable during the summer season. The study's findings support the idea of management intervention to increase the quality of grazing systems.
Assuntos
Ração Animal , Lactação , Ração Animal/análise , Animais , Biomassa , Bovinos , Dieta , Feminino , Leite , Valor NutritivoRESUMO
1. Herein, we report the effects of acute or chronic forced swimming on vascular responsiveness to angiotensin (Ang) II. 2. The possible involvement of locally produced substances, such as nitric oxide (NO) and prostanoids, in these effects were studied in rat thoracic aorta and superior mesenteric arteries. 3. Chronic, but not acute, swimming reduced the efficacy (maximal effect; Emax) of AngII in thoracic aorta and mesenteric arteries, either with intact or denuded endothelium. 4. The efficacy of AngII was reduced in the presence of indomethacin in mesenteric arteries, but not in the aorta, from either control or chronically stressed rats. 5. Treatment with NG-monomethyl-l-arginine reversed the effect of chronic stress on the response to AngII, suggesting that chronic stress may increase non-endothelial NO activity in both the aorta and mesenteric arteries. 6. The effects of acute and chronic stress on vascular reactivity were selective for AngII because no changes were observed on the effects of phenylephrine.
Assuntos
Músculo Liso Vascular/metabolismo , Óxido Nítrico/metabolismo , Condicionamento Físico Animal/métodos , Estresse Fisiológico/metabolismo , Natação/fisiologia , Angiotensina II/antagonistas & inibidores , Angiotensina II/farmacologia , Animais , Aorta Torácica/citologia , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/lesões , Corticosterona/sangue , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/lesões , Endotélio Vascular/fisiologia , Indometacina/farmacologia , Masculino , Artéria Mesentérica Superior/efeitos dos fármacos , Artéria Mesentérica Superior/fisiologia , Músculo Liso Vascular/química , Músculo Liso Vascular/efeitos dos fármacos , Fenilefrina/farmacologia , Condicionamento Físico Animal/fisiologia , Ratos , Ratos Wistar , ômega-N-Metilarginina/farmacologiaRESUMO
Cromoglycate is accumulated on a poly-L-lysine (PLL) modified carbon electrode best from pH 4 solution, where it is anionic and the PLL is cationic, and at which pH the cromoglycate gives a good reduction peak at -0.82 V. The PLL film can be regenerated readily by washing the electrode with 3 M sodium hydroxide solution, in which the PLL is deprotonated. Regeneration of the film is not required as frequently when larger amounts of PLL are incorporated into it. This allows standard addition procedures to be carried out without regenerating the electrode. Linear calibration graphs have been obtained typically in the range 0.1-1.5 microg ml(-1). Detection limits have been calculated to be 10 ng ml(-1). The standard addition method has been applied satisfactorily to diluted urine solutions.
RESUMO
Clotrimazole was shown to react at room temperature in Britton Robinson buffer pH 2 with the reactive dye Procion Red HE-3B. The product exhibited a differential pulse polarographic peak at -0.38 V, which was well separated from the peaks of the reactive dye at -0.08, -0.80 and -0.95 V, and this allowed the indirect determination of clotrimazole in the presence of excess of the reactive dye. The method has been applied satisfactorily to the determination of clotrimazole in pharmaceutical formulations, calibration graphs are rectilinear up to at least 40 microg ml(-1). The detection limit was calculated to be 2.6 microg ml(-1) (3 sigma).
Assuntos
Clotrimazol/análise , Química Farmacêutica , Clotrimazol/química , Corantes , Concentração de Íons de Hidrogênio , Polarografia/métodos , Temperatura , Fatores de Tempo , Triazinas/químicaRESUMO
The phytochemical investigation of the hexane extract of Iryanthera juruensis (Myristicaceae) fruits led to the isolation of two tocotrienols and four lignans which exhibited antioxidant activity towards beta-carotene on TLC autographic assay. Two inactive quinones and three omega-arylalkanoic acids were also isolated. The isolates were investigated for their redox properties using cyclic voltammetry. The structure elucidation of the new compounds (one tocotrienol. one quinone and three omega-arylalkanoic acids) was based on analysis of spectroscopic data.
Assuntos
Antioxidantes/química , Lignanas/química , Magnoliopsida/química , Vitamina E/análogos & derivados , Antioxidantes/isolamento & purificação , Lignanas/isolamento & purificação , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Espectrometria de Massas por Ionização por Electrospray , Vitamina E/química , Vitamina E/isolamento & purificaçãoRESUMO
OBJECTIVE: Rheumatic fever (RF) is a multisystem inflammatory disease that develops as a sequel of untreated throat infection by the group A beta-hemolytic streptococcus. As HLA antigens are known to be important in controlling immunological responsiveness, studies have investigated HLA antigen association with RF. Studies with Caucasians, Black Americans, and Indians showed associations with HLA-DR4, DR2, and DR3, respectively. One study on a Brazilian population suggested an association with HLA-DR7 and HLA-DR53. We investigated the association between RF and antigens HLA-DR7 and DR53 in the white Brazilian population. METHODS: Thirty-five patients and 209 healthy individuals living in the northern region of the state of Parana, Brazil, were used as test and control groups, respectively. Classical statistical methods were used to compare HLA frequencies between these groups. Results. Data confirmed positive association with HLA-DR7 (46.7 vs. 25.7%; p = 0.015), but not with HLA-DR53 (54.3 vs. 44.5%; p = 0.28). The relative risk and etiologic fractions were 2.4 and 0.27%, respectively. CONCLUSION: Positive association between HLA-DR7 specificity and RF was observed in the white Brazilian population by 2 independent studies, supporting the hypothesis of the involvement of genetic factors in susceptibility of rheumatic fever.
Assuntos
Antígeno HLA-DR7/genética , Febre Reumática/genética , Febre Reumática/imunologia , Brasil , Frequência do Gene , Predisposição Genética para Doença , Antígenos HLA-DQ/genética , Antígenos HLA-DR/genética , Cadeias HLA-DRB4 , Humanos , População Branca/genéticaRESUMO
The aim of this study was to determine the coverage of municipal activities in terms of the control of Aedes aegypti and/or Aedes albopictus by routine house-to-house visits and by emergency activity, carried out between 1989 and 1995 in the area of São José do Rio Prêto, São Paulo State, and to evaluate the cross-correlation between them and the Breteau index (BI). For towns with up to 50,000 real estate properties, the joint coverage by routine and emergency activities was mostly appropriate and the routine activities showed a negative cross-correlation with the BI. For the county seat (more than 50,000 real estate properties), the coverage provided by the above activities was not correlated with the BI. In general, the coverage was inversely proportional to town size. Emergency activities did not show a correlation with the BI in any town size range, proving to be ineffective.