Abstract Data about the impacts of hemodialysis on antioxidant status and markers of oxidative stress are controversial, probably due to the use of different methodological approaches. The aim of this study was to assess the changes in the oxidative damage markers and antioxidant enzymes, and the serum antioxidant capacity by using in vitro model systems of free radical generation before and after one hemodialysis session. Blood samples were collected from 40 patients with kidney failure before and after hemodialysis. In pre- and post-hemodialysis serum samples, concentrations of biomarkers of oxidative damage and the activities of antioxidant enzymes were measured, as well as the in vitro antioxidant potential. The high concentrations of oxidative stress markers in serum of kidney failure patients were decreased after one hemodialysis session. In pre-hemodialysis, low activities of antioxidant enzymes were observed, including paraoxonase-1, however paraoxonase-1 activity was partially recovered after hemodialysis. Crocin bleaching and radical scavenging assays showed that serum antioxidant potential was decreased after hemodialysis. Although one hemodialysis session increased paraoxonase-1 activity and decreased oxidative stress markers, it caused a decrease in the serum antioxidant potential. Future research is needed to prospect strategies to mitigate the impacts of oxidative stress in the scenario of hemodialysis repetitions. controversial approaches 4 pre posthemodialysis post measured prehemodialysis, prehemodialysis hemodialysis, pre-hemodialysis observed paraoxonase1, paraoxonase1 paraoxonase 1, 1 paraoxonase- repetitions

Abstract: The aim of this study was investigate the effects of a low-protein, high-carbohydrate (LPHC) diet introduced to rats soon after weaning. The animals were distributed in the following groups: LPHC45: fed an LPHC diet (6%-protein, 74%-carbohydrate) for 45 days; C45: fed a control (C) diet (17%-protein, 63%-carbohydrate) for 45 days; R (Reverse): fed with LPHC for 15 days followed by C diet for 30 days. The LPHC45 group showed alterations in the energetic balance with an increase in brown adipose tissue, and in glucose tolerance, and lower final body weight, muscle mass and total protein in blood when compared with C45 group. The HOMA-IR index was similar between LPHC45 and C45 groups, but this parameter was lower in LPHC45 compared with R groups. Serum adiponectin was higher in LPHC45 group than C45 and R groups. The R group presented higher fed insulin than C45 and LPHC45 and higher T4 compared with C45 group. Total cholesterol in R group was higher when compared with LPHC45 group. Thus, the data show that the change of the diet LPHC for a balanced diet led to different metabolic evolution and suggest that the different response can be due to different levels of adiponectin.

RESUMO Mudanças adaptativas no metabolismo de carboidratos e lipídios induzidas por 7, 15, 30, 60, 90, 150 e 200 dias de jejum foram investigadas em tilápia vermelha (Oreochromis sp.). Níveis de glicose plasmática, lactato e ácidos graxos livres (FFA), glicogênio hepático e muscular, conteúdo de lipídio total e taxas de liberação de FFA de tecido adiposo mesentérico (MAT) foram mensurados. Níveis de glicose plasmática apresentaram diferenças significativas apenas após 90 dias de jejum, quando a glicemia estava 34% menor (50±5mg.dL-1) do que a encontrada em peixes alimentados (74±1mg.dL-1), permanecendo relativamente constante em até 200 dias de jejum. O conteúdo de glicogênio hepático ("15%) em tilápias alimentadas diminuiu 40% em 7 dias de jejum. Após 60, 90 e 150 dias de jejum, níveis plasmáticos de FFA aumentaram 49%, 64% e 90%, respectivamente, quando comparados com os valores obtidos para peixes alimentados. Em concordância com o aumento de FFA plasmático, o jejum induziu um aumento claro da atividade lipolítica em MAT incubada in vitro. A adição de isobutilmetilxantina (inibidor da cAMP-fosfodiesterase) e isoproterenol (agonista beta adrenérgico não-seletivo) ao meio de incubação induziu uma redução da lipólise em peixes em jejum, diferentemente do que já foi observado no tecido adiposo de mamíferos. Este estudo permitiu uma avaliação fisiológica da resposta de tilápia vermelha ao jejum.

ABSTRACT Adaptive changes of carbohydrate and lipid metabolism induced by 7, 15, 30, 60, 90, 150 and 200 days of fasting were investigated in red tilapia (Oreochromis sp.). Plasma glucose, lactate and free fatty acids (FFA) levels, liver and muscle glycogen and total lipid contents and rates of FFA release from mesenteric adipose tissue (MAT) were measured. Plasma glucose levels showed significant differences only after 90 days of fasting, when glycemia was 34% lower (50±5mg.dL-1) than fed fish values (74±1mg.dL-1), remaining relatively constant until 200 days of fasting. The content of liver glycogen ("15%) in fed tilapia fell 40% in 7 days of food deprivation. In 60, 90 and 150 days of fasting, plasma FFA levels increased 49%, 64% and 90%, respectively, compared to fed fish values. In agreement with the increase in plasma FFA, fasting induced a clear increase in lipolytic activity of MAT incubated in vitro. Addition of isobutylmethylxanthine (cAMP-phosphodiesterase inhibitor) and isoproterenol (non selective beta adrenergic agonist) to the incubation medium induced a reduction of lipolysis in fasted fish, differently to what was observed in mammal adipose tissue. This study allowed a physiological assessment of red tilapia response to starvation.