Principles for integrating reactive species into in vivo biological processes:examples from exercise physiology

The equivocal role of reactive species and redox signaling in exercise responses and adaptations is an example clearly showing the inadequacy of current redox biology research to shed light on fundamental biological processes in vivo. Part of the answer probably relies on the extreme complexity of the in vivo redox biology and the limitations of the currently applied methodological and experimental tools. We propose six fundamental principles that should be considered in future studies to mechanistically link reactive species production to exercise responses or adaptations: 1) identify and quantify the reactive species, 2) determine the potential signaling properties of the reactive species, 3) detect the sources of reactive species, 4) locate the domain modified and verify the (ir)reversibility of post-translational modifications, 5) establish causality between redox and physiological measurements, 6) use selective and targeted antioxidants. Fulfilling these principles requires an idealized human experimental setting, which is certainly a utopia. Thus, researchers should choose to satisfy those principles, which, based on scientific evidence, are most critical for their specific research question

Olive oil with high polyphenolic content induces both beneficial and harmful alterations on rat redox status depending on the tissue

Olive oil (OO) possesses a predominant role in the diet of Mediterranean countries. According to a health claim approved by the European Food Safety Authority, OO protects against oxidative stress‑induced lipid peroxidation in human blood, when it contains at least 5 mg of hydroxytyrosol and its derivatives per 20 g. However, studies regarding the effects of a total OO biophenols on redox status in vivo are scarce and either observational and do not provide a holistic picture of their action in tissues. Following a series of in vitro screening tests an OO containing biophenols at 800 mg/kg of OO was administered for 14 days to male Wistar rats at a dose corresponding to 20 g OO/per day to humans. Our results showed that OO reinforced the antioxidant profile of blood, brain, muscle and small intestine, it induced oxidative stress in spleen, pancreas, liver and heart, whereas no distinct effects were observed in lung, colon and kidney. The seemingly negative effects of OO follow the recently formulated idea in toxicology, namely the real life exposure scenario. This study reports that OO, although considered a nutritional source rich in antioxidants, it exerts a tissues specific action when administered in vivo

The development and validation of the pandemic medication-assisted treatment questionnaire for the assessment of pandemic crises impact on medication management and administration for patients with opioid use disorders

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The Significance of Redox Biomarkers in the Evaluation of the Antioxidant Profile In Vitro and In Vivo

The present Special Issue of Antioxidants, entitled The Significance of Redox Biomarkers in the Evaluation of the Antioxidant Profile In Vitro and In Vivo, ten research articles emphasize the significance of adopting reliable redox biomarkers to determine the antioxidant activities of bioactive compounds in vitro and to assess blood and tissue redox status in vivo [...

Administration of exercise-conditioned plasma alters muscle catalase kinetics in rat: An argument for in vivo-like Km instead of in vitro-like Vmax

Maximal velocity (Vmax) is a well established biomarker for the assessment of tissue redox status. There is scarce evidence, though, that it does not probably reflect sufficiently in vivo tissue redox profile. Instead, the Michaelis constant (Km) could more adequately image tissue oxidative stress and, thus, be a more physiologically relevant redox biomarker. Therefore, the aim of the present study was to side-by-side compare Vmax and Km of an antioxidant enzyme after implementing an in vivo set up that induces alterations in tissue redox status. Forty rats were divided into two groups including rats injected with blood plasma originating from rats that had previously swam until exhaustion and rats injected with blood plasma originating from sedentary rats. Tail-vein injections were performed daily for 21 days. Catalase Vmax and Km measured in gastrocnemius muscle were increased after administration of the exercise-conditioned plasma, denoting enhancement of the enzyme activity but impairment of its affinity for the substrate, respectively. These alterations are potential adaptations stimulated by the administered plasma pointing out that blood is an active fluid capable of regulating tissue homeostasis. Our findings suggest that Km adequately reflects in vivo modifications of skeletal muscle catalase and seems to surpass Vmax regarding its physiological relevance and biological interpretation. In conclusion, Km can be regarded as an in vivo-like biomarker that satisfactorily images the intracellular environment, as compared to Vmax that could be aptly parallelized with a biomarker that describes tissue oxidative stress in an in vitro manner

Patients Undergoing Surgery for Hip Fractures Suffer from Severe Oxidative Stress as Compared to Patients with Hip Osteoarthritis Undergoing Total Hip Arthroplasty

Hip fractures are associated with the highest degree of morbidity and mortality of all fractures in elderly patients and pose a major risk for subsequent fractures. Patients with hip fractures also present accelerated bone turnover despite early stable fracture fixation and early mobilization. We aimed to evaluate oxidative stress in two groups of patients (25 patients each, matched for age, side, and BMI) who underwent internal fixation of hip fractures and total hip arthroplasty for hip osteoarthritis. Blood samples were taken from all patients during admission, the day of surgery, the 4th postoperative day, and the 15th postoperative day. Reduced (GSH) and oxidized (GSSG) glutathione, GSH/GSSG, catalase (CAT), thiobarbituric acid reactive substances (TBARS), protein carbonyls (PC), and total antioxidant capacity (TAC) as a widely used battery of redox biomarkers were recorded from blood samples. Patients with hip fractures who undergo fixation surgery, compared to those with hip osteoarthritis, suffer significant oxidative stress with an active but insufficient first line of oxidative defense, an intensive first line reaction, a very active second line of oxidative defense, and a low plasma antioxidant capacity. Surgery worsened already present lipid- and protein-related tissue damage. The severe oxidative stress observed may explain high morbidity and mortality rates and high bone turnover status, as well as the high incidence of refractures. Furthermore, the question of whether antioxidant therapy measures should be introduced in the management of hip fracture patients is raised

Spectrophotometric assays for measuring redox biomarkers in blood and tissues: the NADPH network

Nicotinamide adenine dinucleotide (NAD+/NADH) along with its phosphorylated form (NADP+/NADPH) are two molecules ubiquitously present in all organisms, and they play key roles as cofactors in fundamental catabolic and anabolic processes, respectively. The oxidation of NADPH to NADP+ initiates a cascade of reactions, where a network of molecules is implicated. The molecules of this cascade form a network with eminent translational potential in redox metabolism. A special point of interest is that spectrophotometric assays have been developed both for NADH/NADPH and the molecules directly regulated by them. Therefore, crucial molecules of the NADPH-dependent redox network can be measured, and the results can be used to assess the bioenergetic and/or oxidative stress status. The main aim of this review is to collectively present the NADPH-related molecules, namely NADPH, NADH, NAD+ kinase, NADPH oxidase, peroxiredoxin, thioredoxin, thioredoxin reductase, and nitric oxide synthase, that can be measured in blood and tissues with the use of a spectrophotometer, which is probably the most simple, inexpensive and widely used tool in biochemistry. We are providing the researchers with reliable and valid spectrophotometric assays for the measurement of the most important biomarkers of the NADPH network in blood and other tissues, thus allowing the opportunity to follow the redox changes in response to a stimulus

A Mixture of Endocrine Disruptors and the Pesticide Roundup^® Induce Oxidative Stress in Rabbit Liver When Administered under the Long-Term Low-Dose Regimen: Reinforcing the Notion of Real-Life Risk Simulation

Humans are exposed to xenobiotic mixtures daily through the long-term, low-dose regimen. Investigations designed to simulate this exposure profile approach the real-life risk simulation (RLRS) idea of modern toxicology. The purpose of the present study was to investigate the effects of 12-month exposure of New Zealand rabbits to a xenobiotic mixture comprising seven endocrine disruptors (EDs), which are chemical substances raising great concerns for human health, as well as the herbicide glyphosate, and its commercial formulation Roundup®, on blood and tissues redox status. It is reported herein that at the systemic level, the administration of the EDs mixture induced perturbations of blood redox homeostasis at 3 months, whereas at 6 and 12 months, it activated redox adaptations. Contrariwise, exposure to glyphosate and Roundup®, individually, caused mainly disturbances of blood redox equilibrium. At the tissue level, particularly in the liver, the administration of both the EDs mixture and Roundup® induced oxidative stress, whereas glyphosate did not affect it. The RLRS notion appears to be confirmed through these findings. Indeed, the administration of the EDs mixture and Roundup®, under the long-term, low-dose regimen, elicited detrimental effects on the redox status of the liver, a crucial tissue with a valuable biological role in the detoxification of organisms from xenobiotics