Short-term Physiological Changes In Roots And Leaves Of Sugarcane Varieties Exposed To H2o2 In Root Medium.

The aim of this study was to evaluate the differential sensitivity of sugarcane genotypes to H2O2 in root medium. As a hypothesis, the drought tolerant genotype would be able to minimize the oxidative damage and maintain the water transport from roots to shoots, reducing the negative effects on photosynthesis. The sugarcane genotypes IACSP94-2094 (drought tolerant) and IACSP94-2101 (drought sensitive) were grown in a growth chamber and exposed to three levels of H2O2 in nutrient solution: control; 3mmolL(-1) and 80mmolL(-1). Leaf gas exchange, photochemical activity, root hydraulic conductance (Lr) and antioxidant metabolism in both roots and leaves were evaluated after 15min of treatment with H2O2. Although, root hydraulic conductance, stomatal aperture, apparent electron transport rate and instantaneous carboxylation efficiency have been reduced by H2O2 in both genotypes, IACSP94-2094 presented higher values of those variables as compared to IACSP94-2101. There was a significant genotypic variation in relation to the physiological responses of sugarcane to increasing H2O2 in root tissues, being root changes associated with modifications in plant shoots. IACSP94-2094 presented a root antioxidant system more effective against H2O2 in root medium, regardless H2O2 concentration. Under low H2O2 concentration, water transport and leaf gas exchange of IACSP94-2094 were less affected as compared to IACSP94-2101. Under high H2O2 concentration, the lower sensitivity of IACSP94-2094 was associated with increases in superoxide dismutase activity in roots and leaves and increases in catalase activity in roots. In conclusion, we propose a general model of sugarcane reaction to H2O2, linking root and shoot physiological responses.

Activation Of The Low Molecular Weight Protein Tyrosine Phosphatase In Keratinocytes Exposed To Hyperosmotic Stress.

Herein, we provide new contribution to the mechanisms involved in keratinocytes response to hyperosmotic shock showing, for the first time, the participation of Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP) activity in this event. We reported that sorbitol-induced osmotic stress mediates alterations in the phosphorylation of pivotal cytoskeletal proteins, particularly Src and cofilin. Furthermore, an increase in the expression of the phosphorylated form of LMWPTP, which was followed by an augment in its catalytic activity, was observed. Of particular importance, these responses occurred in an intracellular milieu characterized by elevated levels of reduced glutathione (GSH) and increased expression of the antioxidant enzymes glutathione peroxidase and glutathione reductase. Altogether, our results suggest that hyperosmostic stress provides a favorable cellular environment to the activation of LMWPTP, which is associated with increased expression of antioxidant enzymes, high levels of GSH and inhibition of Src kinase. Finally, the real contribution of LMWPTP in the hyperosmotic stress response of keratinocytes was demonstrated through analysis of the effects of ACP1 gene knockdown in stressed and non-stressed cells. LMWPTP knockdown attenuates the effects of sorbitol induced-stress in HaCaT cells, mainly in the status of Src kinase, Rac and STAT5 phosphorylation and activity. These results describe for the first time the participation of LMWPTP in the dynamics of cytoskeleton rearrangement during exposure of human keratinocytes to hyperosmotic shock, which may contribute to cell death.

Theobromine Increases Nad⁺/sirt-1 Activity And Protects The Kidney Under Diabetic Conditions.

Reduction in sirtuin 1 (Sirt-1) is associated with extracellular matrix (ECM) accumulation in the diabetic kidney. Theobromine may reduce kidney ECM accumulation in diabetic rats. In the current study, we aimed to unravel, under diabetic conditions, the mechanism of kidney ECM accumulation induced by a reduction in Sirt-1 and the effect of theobromine in these events. In vitro, we used immortalized human mesangial cells (iHMCs) exposed to high glucose (HG; 30 mM), with or without small interfering RNA for NOX4 and Sirt-1. In vivo, spontaneously hypertensive rats (SHR) were rendered diabetic by means of streptozotocin and studied after 12 wk. The effects of treatment with theobromine were investigated under both conditions. HG leads to a decrease in Sirt-1 activity and NAD(+) levels in iHMCs. Sirt-1 activity could be reestablished by treatment with NAD(+), silencing NOX4, and poly (ADP-ribose) polymerase-1 (PARP-1) blockade, or with theobromine. HG also leads to a low AMP/ATP ratio, acetylation of SMAD3, and increased collagen IV, which is prevented by theobromine. Sirt-1 or AMPK blockade abolished these effects of theobromine. In diabetic SHR, theobromine prevented increases in albuminuria and kidney collagen IV, reduced AMPK, elevated NADPH oxidase activity and PARP-1, and reduced NAD(+) levels and Sirt-1 activity. These results suggest that in diabetes mellitus, Sirt-1 activity is reduced by PARP-1 activation and NAD(+) depletion due to low AMPK, which increases NOX4 expression, leading to ECM accumulation mediated by transforming growth factor (TGF)-β1 signaling. It is suggested that Sirt-1 activation by theobromine may have therapeutic potential for diabetic nephropathy.

Myoglobins: the link between discoloration and lipid oxidation in muscle and meat

Aerobic metabolism changes rapidly to glycolysis post-mortem resulting in a pH-decrease during the transformation of muscle in to meat affecting ligand binding and redox potential of the heme iron in myoglobin, the meat pigment. The inorganic chemistry of meat involves (i) redox-cycling between iron(II), iron(III), and iron(IV)/protein radicals; (ii) ligand exchange processes; and (iii) spin-equilibra with a change in coordination number for the heme iron. In addition to the function of myoglobin for oxygen storage, new physiological roles of myoglobin are currently being discovered, which notably find close parallels in the processes in fresh meat and nitrite-cured meat products. Myoglobin may be characterized as a bioreactor for small molecules like O2, NO, CO, CO2, H2O, and HNO with importance in bio-regulation and in protection against oxidative stress in vivo otherwise affecting lipids in membranes. Many of these processes may be recognised as colour changes in fresh meat and cured meat products under different atmospheric conditions, and could also be instructive for teaching purposes.

Stress no trabalho em professores de educação fisica do sistema municipal de educação, na comunidade de Concepcion, oitava região, Chile

Universidade Estadual de Campinas. Faculdade de Educação Física

Deep Water Running para redução da gordura corporal em mulheres na meia idade : estudo de intervenção em Campinas - SP

Universidade Estadual de Campinas . Faculdade de Educação Física

Efeitos da ingestão de cafeína Em exercício aeróbio de alta intensidade em hipóxia : parâmetros fisiológicos e perceptuais = Effects of caffeine ingestion on high-intensity aerobic exercise in hypoxia : physiological and perceptual parameters

Universidade Estadual de Campinas . Faculdade de Educação Física

Avaliação da qualidade de vida e dos sintomas de stress em mulheres menopausadas com disfunção da articulação temporomandibular

Universidade Estadual de Campinas . Faculdade de Educação Física

Fatores de stress em jogadores de futebol profissional

Universidade Estadual de Campinas . Faculdade de Educação Física

A variação da acuidade visual durante esforços fisicos em atletas com baixa visão

Universidade Estadual de Campinas . Faculdade de Educação Física

Polymerization shrinkage stress of composites photoactivated by different light sources

The purpose of this study was to compare the polymerization shrinkage stress of composite resins (microfilled, microhybrid and hybrid) photoactivated by quartz-tungsten halogen light (QTH) and light-emitting diode (LED). Glass rods (5.0 mm x 5.0 cm) were fabricated and had one of the surfaces air-abraded with aluminum oxide and coated with a layer of an adhesive system, which was photoactivated with the QTH unit. The glass rods were vertically assembled, in pairs, to a universal testing machine and the composites were applied to the lower rod. The upper rod was placed closer, at 2 mm, and an extensometer was attached to the rods. The 20 composites were polymerized by either QTH (n=10) or LED (n=10) curing units. Polymerization was carried out using 2 devices positioned in opposite sides, which were simultaneously activated for 40 s. Shrinkage stress was analyzed twice: shortly after polymerization (t40s) and 10 min later (t10min). Data were analyzed statistically by 2-way ANOVA and Tukey's test (a=5%). The shrinkage stress for all composites was higher at t10min than at t40s, regardless of the activation source. Microfilled composite resins showed lower shrinkage stress values compared to the other composite resins. For the hybrid and microhybrid composite resins, the light source had no influence on the shrinkage stress, except for microfilled composite at t10min. It may be concluded that the composition of composite resins is the factor with the strongest influence on shrinkage stress.

Psychological stress and recurrent aphthous stomatitis

INTRODUCTION AND OBJECTIVES: Recurrent aphthous stomatitis (RAS) is the most common type of ulcerative disease of the oral mucosa. Despite its worldwide occurrence and the extensive amount of research that has been devoted to the subject, the etiology of RAS remains unclear. Nevertheless, several hereditary, nutritional, infectious and psychological factors have been associated with RAS. The aim of this case-control study was to assess the influence of psychological stress on the manifestation of RAS. METHOD: Fifty patients were enrolled in the trial. Twenty-five RAS patients constituted the study group and another 25 non-RAS patients who were similarly matched for sex, age and socioeconomic status constituted the control group. Each patient was evaluated in terms of the four domains of stress (emotional, physical, social and cognitive) using an internationally validated questionnaire, which was comprised of 59 items and measured the frequency and intensity of stress symptoms. The RAS group was interviewed during an active RAS episode. Completed questionnaires were submitted to proper analytical software and interpreted by an expert psychologist. RESULTS: There was a higher level of psychological stress among RAS group patients when compared to the control group (P < 0.05). CONCLUSION: Psychological stress may play a role in the manifestation of RAS; it may serve as a trigger or a modifying factor rather than being a cause of the disease.

Influência do transporte e mudança de local de manejo nas variáveis fisiológicas e produtivas de cabras Alpinas

Estudaram-se o efeito do transporte e a mudança de local de manejo sobre a produção e a composição do leite e sobre as variáveis fisiológicas, utilizando-se 12 cabras da raça Alpina em final de lactação. Semanalmente, foram mensuradas a produção e composição do leite e a contagem de células somáticas, além do volume do leite residual após administração de ocitocina. Foram colhidas amostras de sangue para dosagem hormonal (cortisol) e enzimática (glicose) no plasma no dia do transporte: antes (7h10min) e após (8h20min, 8h30min e 10h30min) o transporte. Nas três semanas subsequentes ao transporte, também foram colhidas amostras de sangue às 8h20min. Obtiveram-se teores mais elevados (P<0,05) de cortisol e glicose após o transporte e a mudança de local de manejo, e menor produção de leite (P<0,05) um dia após o evento. Porcentagem de gordura (P<0,05) e contagem de células somáticas apresentaram diferenças significativas (P<0,05) após o transporte. Os resultados permitem concluir que o transporte é um agente estressor que pode, momentaneamente, influenciar a produção animal.

Concentrações plasmáticas de testosterona, triiodotironina (T3) e tiroxina (T4) em bodes submetidos ao estresse calórico

Para verificar o efeito do estresse calórico (EC) nas concentrações plasmáticas de testosterona, triiodotironina (T3) e tiroxina (T4), oito bodes, das raças Saanen (n=4) e Alpina (n=4), foram mantidos em câmara bioclimática, sob condições de termoneutralidade (13,0ºC a 26,7ºC) durante 30 dias e, após um período (60 dias) de descanso, submetidos ao EC (23,7ºC a 34,0ºC) por 30 dias. Para minimizar as variações sazonais nos perfis hormonais devido ao fotoperíodo, durante toda fase experimental, incluindo a de adaptação em condições de termoneutralidade (30 dias), o fotoperíodo foi controlado utilizando-se alternância de dias longos (16h de luz e 8h de escuro) e de dias curtos (8h de luz e 16h de escuro) a cada 30 dias. As amostras de sangue foram coletadas duas vezes por semana durante cinco semanas. No conjunto das raças, o EC não influenciou (P>0,05) as concentrações de testosterona (1,8±0,2 vs 1,3±0,2ng/ml) e nem a de T4 (52,7±2,8 vs 50,0±2,8ng/ml). Houve declínio (P<0,01) das concentrações de T3 nos animais submetidos ao experimento (1,3±0,1 vs 1,0±0,1ng/ml), mas a redução foi observada somente nos bodes Saanen. Em ambas as raças, as concentrações de T3 e T4 variaram (P<0,01) conforme o dia da coleta das amostras de sangue. O EC foi suficiente para produzir uma resposta fisiológica com redução das concentrações plasmáticas de T3 em bodes das raças Saanen, mas não da raça Alpina, assim como não foi capaz de alterar os níveis plasmáticos de testosterona e nem de T4.

Respostas fisiológicas de plantas amazônicas de regiões alagadas às mudanças climáticas globais

Conforme previsões do último relatório do IPCC (Intergovernmental Panel of Climatic Change) em 2007, até meados deste século haverá um aumento na concentração de CO2 na atmosfera podendo chegar a 720 μmol mol-1. Consequentemente haverá uma elevação da temperatura de até +3 °C, o que ocorrerá em conjunto com mudanças no padrão de precipitação. O mesmo relatório sugere que isto poderá acarretar uma substituição gradual da floresta tropical por vegetação similar a uma savana na parte oriental da Amazônia, porém nada é conclusivo. Diante dessas possibilidades, pergunta-se - Como as espécies de árvores que compõem as regiões de alagamento da Amazônia irão responder às alterações climáticas por vir? Apesar dessas previsões serem pessimistas, o alagamento ainda ocorrerá por vários anos na Amazônia e é de grande importância compreender os efeitos do alagamento sobre as respostas fisiológicas das plantas num contexto das mudanças climáticas. Os principais efeitos sobre a sinalização metabólica e hormonal durante o alagamento são revisados e os possíveis efeitos que as mudanças climáticas poderão ter sobre as plantas amazônicas são discutidos. As informações existentes sugerem que sob alagamento, as plantas tendem a mobilizar reservas para suprir a demanda de carbono necessário para a manutenção do metabolismo sob o estresse da falta de oxigênio. Até certo limite, com o aumento da concentração de CO2, as plantas tendem a fazer mais fotossíntese e a produzir mais biomassa, que poderão aumentar ainda mais com um acréscimo de temperatura de até 3 °C. Alternativamente, com o alagamento, há uma diminuição geral do potencial de crescimento e é possível que quando em condições de CO2 e temperatura elevados os efeitos positivo e negativo se somem. Com isso, as respostas fisiológicas poderão ser amenizadas ou, ainda, promover maior crescimento para a maioria das espécies de regiões alagáveis até o meio do século. Porém, quando a temperatura e o CO2 atingirem valores acima dos ótimos para a maioria das plantas, estas possivelmente diminuirão a atividade fisiológica.