Using the MitoB method to assess levels of reactive oxygen species in ecological studies of oxidative stress

In recent years evolutionary ecologists have become increasingly interested in the effects of reactive oxygen species (ROS) on the life-histories of animals. ROS levels have mostly been inferred indirectly due to the limitations of estimating ROS from in vitro methods. However, measuring ROS (hydrogen peroxide, H2O2) content in vivo is now possible using the MitoB probe. Here, we extend and refine the MitoB method to make it suitable for ecological studies of oxidative stress using the brown trout Salmo trutta as model. The MitoB method allows an evaluation of H2O2 levels in living organisms over a timescale from hours to days. The method is flexible with regard to the duration of exposure and initial concentration of the MitoB probe, and there is no transfer of the MitoB probe between fish. H2O2 levels were consistent across subsamples of the same liver but differed between muscle subsamples and between tissues of the same animal. The MitoB method provides a convenient method for measuring ROS levels in living animals over a significant period of time. Given its wide range of possible applications, it opens the opportunity to study the role of ROS in mediating life history trade-offs in ecological settings

Position Statement on Exercise Dosage in Rheumatic and Musculoskeletal Diseases: The Fole of the IMPACT-RMD Toolkit

There is convincing evidence to suggest that exercise interventions can significantly improve disease-related outcomes as well as comorbidities in rheumatic and musculoskeletal diseases (RMDs). All exercise interventions should be appropriately defined by their dose, which comprises of two components: a) the FITT (frequency, intensity, time and type) and b) the training (ie, specificity, overload, progression, initial values, reversibility, and diminishing returns) principles. In the published RMD literature, exercise dosage is often misreported, which in "pharmaceutical treatment terms", this would be the equivalent of receiving the wrong medication dosage. Lack of appropriately reporting exercise dosage in RMDs, therefore, results in limited clarity on the effects of exercise interventions on different outcomes while it also hinders reproducibility, generalisability and accuracy of research findings. Based on the collective but limited current knowledge, the main purpose of the present Position Statement is to provide specific guidance for RMD researchers to help improve the reporting of exercise dosage and help advance research into this important field of investigation. We also propose the use of the IMPACT-RMD toolkit, a tool that can be used in the design and reporting phase of every trial

Flavonoid Glycosides Isolated from Unique Legume Plant Extracts as Novel Inhibitors of Xanthine Oxidase

Legumes and the polyphenolic compounds present in them have gained a lot of interest due to their beneficial health implications. Dietary polyphenolic compounds, especially flavonoids, exert antioxidant properties and are potent inhibitors of xanthine oxidase (XO) activity. XO is the main contributor of free radicals during exercise but it is also involved in pathogenesis of several diseases such as vascular disorders, cancer and gout. In order to discover new natural, dietary XO inhibitors, some polyphenolic fractions and pure compounds isolated from two legume plant extracts were tested for their effects on XO activity. The fractions isolated from both Vicia faba and Lotus edulis plant extracts were potent inhibitors of XO with IC50 values range from 40-135 mu g/mL and 55-260 mu g/mL, respectively. All the pure polyphenolic compounds inhibited XO and their K-i values ranged from 13-767 mu M. Ten of the compounds followed the non competitive inhibitory model whereas one of them was a competitive inhibitor. These findings indicate that flavonoid isolates from legume plant extracts are novel, natural XO inhibitors. Their mode of action is under investigation in order to examine their potential in drug design for diseases related to overwhelming XO action

Effects of walking on heart rate recovery, endothelium modulators and quality of life in patients with heart failure

Background: Few studies have addressed the impact of moderate unsupervised everyday physical activity in patients with chronic heart failure (CHF). Design: We investigated the effects of a 12-week walking programme as the sole exercise intervention on heart rate recovery (HRR), index of the autonomic system equilibrium, serum modulators of endothelial function (i.e. asymmetric dimethylarginine (ADMA) and homocysteine), markers of inflammation and oxidative stress and quality of life measures (i.e. SF-36 and the Zung depression scale) in CHF patients. Methods: Twenty-eight stabilized CHF patients of NYHA class II and III volunteered to participate either in the exercise (n=18) or in the non-exercise (n=10) groups. Ten age-matched healthy volunteers provided reference values. The exercise programme consisted of unsupervised 40-minute walking for five days per week. Results: Repeated measures ANOVA revealed significant improvements in HRR (p < 0.001) in the exercise patients compared to their non-exercise counterparts. ADMA levels in CHF patients at baseline were found higher than the healthy reference volunteers (p < 0.03), while a decrease in ADMA levels after walking was associated with HRR changes (r=0.74, p=0.007). Homocysteine levels both at baseline and at the end of the walking intervention decreased in the exercise group, but were still higher than in the healthy individuals. Average walking distance positively correlated with homocysteine decrease (p < 0.05). Total SF-36 score significantly improved (p < 0.02) mainly due to enhancements in the physical component score (p < 0.026). Conclusion: A 12-week unsupervised walking programme exhibits a pronounced HRR amelioration, possibly attenuates endothelial damage and induces a concomitant improvement in perceived quality of life in CHF patients

Dietary oxidative stress and antioxidant defense with an emphasis on plant extract administration

Eukaryotic cells generally function in a reduced state, but an amount of reactive species is essential for several biochemical processes. The antioxidant network is the defensive mechanism that occurs when the concentration of reactive species exceeds a threshold. Polyphenolic compounds present in plant extracts are potent antioxidants in vitro, but they may promote oxidative stress when administered in animals and humans, especially when given as supplements in exercise, a modality usually adopted as an oxidant stimulus. This is mainly observed when antioxidant molecules are administered separately and not as part of a diet. Exercise is usually adopted as a physiological model for examining the effects of reactive species in human or animal physiology. The use of exercise as a model demonstrates that reactive species do not always have adverse effects, but are necessary in physiological processes that are beneficial for human health. This review summarizes what is known about antioxidant supplementation and demonstrates the need for a meticulous examination of the in vitro findings before applying them to in vivo models. The term "antioxidant" seems elusive, and it is more appropriate to characterize a compound as "antioxidant" if we know in which concentration it is used, when it is used, and under which conditions