From doubly labelled water to half-life; validating radio-isotopic rubidium turnover to measure metabolism in small vertebrates

The doubly labelled water method (DLW) is widely used to measure field metabolic rate (FMR), but it has some limitations. Here, we validate an innovative technique for measuring FMR by comparing the turnover of isotopic rubidium (86Rb kb) with DLW depletion and the rate of CO2 production (V·co2) measured by flow-through respirometry (FTR) for two dunnart species (Marsupialia: Dasyuridae), Sminthopsis macroura (17 g) and Sminthopsis ooldea (10 g). The rate of metabolism as assessed by V·co2 (FTR) and 86Rb kb was significantly correlated for both species (S. macroura, r2 = 0·81, P = 1·19 × 10-5; S. ooldea, r2 = 0·63, P = 3·84 × 10-4), as was V·co2 from FTR and DLW for S. macroura (r2 = 0·43, P = 0·039), but not for S. ooldea (r2 = 0·29, P = 0·168). There was no relationship between V·co2 from DLW and 86Rb kb for either species (S. macroura r2 = 0·22, P = 0·169; S. ooldea r2 = 0·21, P = 0·253). We conclude that 86Rb kb provided useful estimates of metabolic rate for dunnarts. Meta-analysis provided different linear relationships between V·co2 and 86Rb kb for endotherms and ectotherms, suggesting different proportionalities between metabolic rate and 86Rb kb for different taxa. Understanding the mechanistic basis for this correlation might provide useful insights into the cause of these taxonomic differences in the proportionality. At present, it is essential that the relationship between metabolic rate and 86Rb kb be validated for each taxon of interest. The advantages of the 86Rb technique over DLW include lower equipment requirements and technical expertise, and the longer time span over which measurements can be made. The 86Rb method might be particularly useful for estimating FMR of groups for which the assumptions of the DLW technique are compromised (e.g. amphibians, diving species and fossorial species), and groups that are practically challenging for DLW studies (e.g. insects). © 2013 British Ecological Society.

Lipid metabolism of commercial layers fed diets containing aflatoxin, fumonisin, and a binder

Aflatoxins (AF) and fumonisins (FU) are a major problem faced by poultry farmers, leading to huge economic losses. This experiment was conducted to determine the effects of AF (1 mg/kg of feed) and FU (25 mg/kg of feed), singly or in combination, on the lipid metabolism in commercial layers and investigate the efficacy of a commercial binder (2 kg/t of feed) on reducing the toxic effects of these mycotoxins. A total of 168 Hisex Brown layer hens, 37 wk of age, were randomized into a 3 × 2 + 1 factorial arrangement (3 diets with no binder containing AF, FU, and AF+FU; 3 diets with binder containing AF, FU, and AF+FU; and a control diet with no mycotoxins and binders), totaling 7 treatments. The hens contaminated with AF showed the characteristic effects of aflatoxicosis, such as a yellow liver, resulting from the accumulation of liver fat, lower values of plasma very low-density lipoprotein and triglycerides, and higher relative weight of the kidneys and liver. Hepatotoxic and nephrotoxic effects of FU were not observed in this study. On the other hand, the FU caused a reduction in small intestine length and an increase in abdominal fat deposition. The glucan-based binder prevented some of the deleterious effects of these mycotoxins, particularly the effects of AF on hepatic lipid metabolism, kidney relative weight, and FU in the small intestine. © 2013 Poultry Science Association Inc.

Leishmaniasis causes oxidative stress and alteration of oxidative metabolism and viability of neutrophils in dogs

The aim of the present study was to test the hypothesis that oxidative stress and alteration of oxidative metabolism and apoptosis of neutrophils in dogs vary with the stage of leishmaniasis and to determine the contribution of uremia to such alterations. Dogs with leishmaniasis were classified into two stages: moderate (Leish II, n = 20) or very severe (i.e. with concurrent uremia; Leish IV, n = 20) according to the LeishVet Consensus. The two leishmaniasis groups were compared with uremic dogs without leishmaniasis (Uremic, n = 10) and to healthy dogs (Control, n = 30). To determine oxidative stress, total antioxidant/oxidant capacity, lipid peroxidation, total glutathione and the plasma antioxidants albumin, uric acid and bilirubin were quantified. Superoxide production was determined using the hydroethidine probe and viability and apoptosis were measured using annexin V-PE by capillary flow cytometry. Oxidative stress was present in both uremia and leishmaniasis with reduced total antioxidant capacity and was associated with increased induced production of superoxide and apoptosis. The greatest amount of oxidants was observed in animals with moderate disease only. Neutrophils from uremic dogs with and without leishmaniasis had decreased viability and an increased apoptosis rate in addition to increased lipid peroxidation. In conclusion, oxidative stress occurs in both stages of leishmaniasis with differences in intensity and levels of plasma markers; however, uremia does contribute to the decreased spontaneous viability of neutrophils in dogs in the final stage of the disease. © 2013 Elsevier Ltd. All rights reserved.

Oxidative stress in sickle cell disease: An overview of erythrocyte redox metabolism and current antioxidant therapeutic strategies

Erythrocytes have an environment of continuous pro-oxidant generation due to the presence of hemoglobin (Hb), which represents an additional and quantitatively significant source of superoxide (O2 •-) generation in biological systems. To counteract oxidative stress, erythrocytes have a self-sustaining antioxidant defense system. Thus, red blood cells uniquely function to protect Hb via a selective barrier allowing gaseous and other ligand transport as well as providing antioxidant protection not only to themselves but also to other tissues and organs in the body. Sickle hemoglobin molecules suffer repeated polymerization/depolymerization generating greater amounts of reactive oxygen species, which can lead to a cyclic cascade characterized by blood cell adhesion, hemolysis, vaso-occlusion, and ischemia-reperfusion injury. In other words, sickle cell disease is intimately linked to a pathophysiologic condition of multiple sources of pro-oxidant processes with consequent chronic and systemic oxidative stress. For this reason, newer therapeutic agents that can target oxidative stress may constitute a valuable means for preventing or delaying the development of organ complications. © © 2013 Elsevier Inc. All rights reserved.

Influence of creatine supplementation on indicators of glucose metabolism in skeletal muscle of exercised rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A Multivariate Calibration Procedure for UV/VIS Spectrometric Monitoring of BHK-21 Cell Metabolism and Growth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sex and reproductive stage differences in the growth, metabolism, feed, fecal production, excretion and energy budget of the Amazon River prawn (Macrobrachium amazonicum)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Muscle glycogen metabolism changes in rats fed early postnatal a fructose-rich diet after maternal protein malnutrition: effects of acute physical exercise at the maximal lactate steady-state intensity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cardiac Energy Metabolism and Oxidative Stress Biomarkers in Diabetic Rat Treated with Resveratrol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)