Production, detection, and adaptive responses to free radicals in exercise

The Effect of Endurance Exercise on Semen Quality in Male Athletes: A Systematic Review

BACKGROUND

Endurance exercise has the potential to affect reproductive function, with amenorrhea in female athletes. However, most studies focus on women. Evidence on the association between endurance exercise and male fertility is limited.

OBJECTIVE

To synthesise existing literature on exercise-induced alterations in semen parameters and to assess the clinical impact on male fertility.

METHODS

Studies reporting on the association between semen parameters and endurance exercise in healthy men were eligible. Men attending fertility clinics were excluded. We searched MEDLINE (PubMed), Embase, SPORTDiscus, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) from their inception to May 28th 2022. JBI Critical Appraisal Tool was used to assess the potential risk of bias.

RESULTS

Thirteen studies met inclusion criteria, reporting on 280 subjects. Eight articles reported on endurance runners, three on cyclists and four on triathletes. Four studies did not find any statistically significant sperm alterations. Five reported significant changes in semen parameters, but these were not clinically relevant, as semen parameters remained well above World Health Organisation (WHO) thresholds. Four articles reported a decrease in semen quality with potential clinical consequences as they found a reduced number of sperm cells exhibiting normal morphology in cyclists and triathletes and a greater amount of DNA fragmentation in triathletes.

CONCLUSION

Endurance exercise can have a negative effect on semen quality, although rarely with a clinically relevant impact on male fertility. Evidence is however limited, with poor quality of the included studies.

REGISTRATION

PROSPERO International prospective register of systematic reviews (CRD42022336753).

Short-term swimming up-regulates pro-inflammatory mediators and cytokines in gilthead seabream (Sparus aurata)

Aerobic swimming exercise in fish has been shown to improve robustness of some species. However, the optimal conditions to be applied and the mechanisms underlying remain unknown. We investigated the effects of 6 h of induced swimming on the immune response of gilthead seabream (Sparus aurata), by analysing markers related to immune status in plasma, skin mucus, gills, heart and head-kidney. Forty fish were individually exercised in swim tunnels by applying different water currents: steady low (SL, 0.8 body lengths (BL) s-1), steady high (SH, 2.3 BL s-1), oscillating low (OL, 0.2/0.8 BL s-1) and oscillating high (OH, 0.8/2.3 BL s-1) velocities, including a non-exercised group with minimal water flow (MF, <0.1 BL s-1). Swimming conditions did not trigger a stress response or anaerobic metabolism, suggested by similar levels of cortisol, lactate, and glucose in plasma among groups. Blood haemoglobin and innate immune parameters in plasma and skin mucus also remained unaltered. However, decreased blood haematocrit was observed in fish swimming on the OL condition. Interestingly, gene expression analysis revealed that the OL condition led to the up-regulation of pro-inflammatory mediators (nfκb1 and mapk3) and cytokines (tnfα, il1β and il6) in gills. A similar response occurred in heart, with an up-regulation of nfκb1, tnfα, il6 and cox2 in the OL condition. Gene expression of these cytokines was unaltered in the head-kidney. The inflammatory response in gills and heart of gilthead seabream triggered by the OL condition highlights the importance of establishing suitable rearing conditions to improve welfare of cultured fish.

Steady-state redox status in circulating extracellular vesicles: A proof-of-principle study on the role of fitness level and short-term aerobic training in healthy young males

Considering the role of redox homeostasis in exercise-induced signaling and adaptation, this study focuses on the exercise training-related intercellular communication of redox status mediated by circulating extracellular vesicles (EVs). 19 healthy young males were divided into trained (TG, 7) and untrained (UG, 12) subjects based on their VO_2MAX. The UG subjects were further randomly distributed in experimental (UG_EX, N = 7) and control (UG_CTRL, N = 5) groups. The steady state of plasma EVs in TG and UG_EX have been characterized for total number and size, as well as cargo redox status (antioxidants, transcription factors, HSPs) before, 3 and 24 h after a single bout of aerobic exercise (30', 70% HRM). Plasma EVs from UG_EX and UG_CTRL have been further characterized after 24 h from the last session of a 5-day consecutive aerobic training or no training, respectively. No differences were detected in the EVs' size and distribution at baseline in TG and UG_EX (p>0.05), while the EVs cargo of UG_EX showed a significantly higher concentration of protein carbonyl, Catalase, SOD2, and HSF1 compared to TG (p<0.05). 5 days of consecutive aerobic training in UG_EX did not determine major changes in the steady-state number and size of EVs. The post-training levels of protein carbonyl, HSF1, Catalase, and SOD2 in EVs cargo of UG_EX resulted significantly lower compared with UG_EX before training and UG_CTRL, resembling the steady-state levels in circulating EVs of TG subjects. Altogether, these preliminary data indicate that individual aerobic capacity influences the redox status of circulating EVs, and that short-term aerobic training impacts the steady-state redox status of EVs. Taking this pilot study as a paradigm for physio-pathological stimuli impacting redox homeostasis, our results offer new insights into the utilization of circulating EVs as biomarkers of exercise efficacy and of early impairment of oxidative-stress related diseases.

Immunologic, Anti-Inflammatory, and Anti-Muscle Damage Profile of Supplemented Vitamin D3 in Healthy Adults on Strenuous Endurance Exercise

Reportedly, strenuous endurance exercise can depress the immune system and induce inflammation and muscle damage. Therefore, this double-blinded, matched-pair study aimed to investigate the impact of vitamin D₃ supplementation on immune response (leukocyte, neutrophil, lymphocyte, CD4⁺, CD8⁺, CD19⁺, and CD56⁺ counts), inflammatory profile (TNF-α and IL-6), muscle damage (CK and LDH levels), as well as aerobic capacity after strenuous endurance exercise in 18 healthy men taking 5000 IU of vitamin D₃ (n = 9) or placebo (n = 9) daily for 4 weeks. Total and differential blood leukocyte counts, levels of cytokines, and muscle damage biomarkers were determined before, immediately after, and 2, 4, and 24 h after exercise. The IL-6, CK, and LDH levels were significantly lower in vitamin D₃ group at 2, 4, and 24 h post exercise (p < 0.05). Maximal and average heart rates during exercise were also significantly lower (p < 0.05). In the vitamin D₃ group, the CD4⁺/CD8⁺ ratio after 4 weeks of supplementation was only significantly lower at post-0 than at baseline and significantly higher at post-2 than at baseline and post-0 (all p < 0.05). Taken together, 5000 IU of daily vitamin D₃ supplementation for 4 weeks exhibited positive effects in terms of increased blood 25(OH)D levels, CD4⁺/CD8⁺ ratio (immune response), and aerobic capacity while inhibiting inflammatory cytokines and CK and LDH (muscle damage) in people performing strenuous endurance exercise.

Ameliorative effect of ellagic acid and Vitamin C against malathion-induced toxicity in testis of adult Wistar rats

The pesticide malathion (MT), an organophosphate, is highly neurotoxic and causes cholinergic disorders as well as cytotoxicity, genotoxicity, mutagenicity, carcinogenicity and reproductive toxicity. Our purpose was to study the effect of ellagic acid (EA) and Vitamin C on the testis against MT-induced toxicity in the rats. Thirty-six adult Wistar rats were employed, separated into six groups and were given treatment for 14 days. The toxicity of MT on the testis was evaluated using a variety of physical parameters, such as mortality rate and body weight, as well as biochemical parameters, such as total protein, total cholesterol, serum glutamic-oxaloacetic transaminase and serum glutamic-pyruvic transaminase, and haematological parameters, such as counts of red blood cells, haemoglobin (Hb) and white blood cells, as well as mean corpuscular volume, mean corpuscular Hb, and mean corpuscular Hb concentration. At the end of the experiment, rats were killed and a histological examination of the testis was performed. A sperm count technique and an analysis of sperm motility were used to determine the sperm quality. Biochemical indicators, sperm count, motility, viability and morphology were significantly decreased with MT. When compared with MT and the control group, EA and Vitamin C administration significantly increased sperm motility and count (p < 0.05). After receiving EA and Vitamin C, biochemical indicators and histological characteristics are also intensified. The results of the current investigation show that EA and Vitamin C can both reduce increased levels of biochemical markers and improve pathological alterations in the testis brought on by MT treatment.

Effect of 8-week high-intensity intermittent running exercise and weight training on muscle and DNA damage in male and female ski major college students

This study assessed changes in blood muscle damage indicators and DNA damage indicators in lymph and urine after 8 weeks of high-intensity intermittent running and weight training in male and female college students majoring in skiing. This study aimed to find an effective training method by investigating differences in the effectiveness between men and women. A total of 20 male and female ski major college students conducted short-term high-intensity intermittent running and weight training in the morning and afternoon, respectively, 3 days a week for 8 weeks for 24 times in total. After 8 weeks of high-intensity intermittent running and weight training, changes in DNA damage indicators in the lymph and urine and muscle damage indicators in the blood were analyzed. The creatine kinase level significantly differed at rest pre-graded exercise testing (GXT) and 60 min of recovery post-GXT after training from that before training between the male and female groups. Although lactate dehydrogenase (LDH) levels decreased in both groups over time, no significant differences in LDH were found between the two groups. Second, DNA 8-hydroxydeoxyguanosine (8-OHdG) in the lymph was significantly different between the two groups at rest pre-GXT and 60 min of recovery post-GXT. 8-OHdG in the urine was significantly lower in the female group only at 60 min of recovery post-GXT. Partial sex differences were found in the reduction of muscle damage and DNA damage after 8 weeks of high-intensity intermittent running and weight training.

Effects of Intestinal Bacterial Hydrogen Gas Production on Muscle Recovery following Intense Exercise in Adult Men: A Pilot Study

This study aimed to examine the effects of hydrogen gas (H₂) produced by intestinal microbiota on participant conditioning to prevent intense exercise-induced damage. In this double-blind, randomized, crossover study, participants ingested H₂-producing milk that induced intestinal bacterial H₂ production or a placebo on the trial day, 4 h before performing an intense exercise at 75% maximal oxygen uptake for 60 min. Blood marker levels and respiratory variables were measured before, during, and after exercise. Visual analog scale scores of general and lower limb muscle soreness evaluated were 3.8- and 2.3-fold higher, respectively, on the morning after treatment than that before treatment during the placebo trial, but not during the test beverage consumption. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations and production rates significantly increased with placebo consumption; no changes were observed with test beverage consumption. After exercise, relative blood lactate levels with H₂-producing milk consumption were lower than those with placebo consumption. A negative correlation was observed between the variation of 8-OHdG and the area under the curve (AUC) of breath H₂ concentrations. Lipid oxidation AUC was 1.3-fold higher significantly with H₂-producing milk than with placebo consumption. Conclusively, activating intestinal bacterial H₂ production by consuming a specific beverage may be a new strategy for promoting recovery and conditioning in athletes frequently performing intense exercises.

Development and Characterization of Oxidatively Responsive Thiol-Ene Networks for Bone Graft Applications

First metatarsophalangeal joint (MPJ) arthroplasty procedures are a common podiatric procedure. However, almost one-third of cases require revision surgeries because of nonunions. Revision or salvage surgery requires more extensive hardware and bone grafts to recreate the first metatarsal. Unfortunately, salvage surgeries have a similar rate of failure attributed to delayed healing, bone graft dissolution, and the lack of bone ingrowth. Furthermore, patients who suffer from neuropathic comorbidities such as diabetes suffer from a diminished healing capacity. An increase in proinflammatory factors and the high presence of reactive oxygen species (ROS) present in diabetics are linked to lower fusion rates. To this end, there is a need for a clinically relevant bone graft to promote bone fusions in patients with neuropathic comorbidities. Incorporating thiol-ene networks for bone scaffolds has demonstrated increased osteogenic biomarkers over traditional polymeric materials. Furthermore, thiol-ene networks can act as antioxidants. Sulfide linkages within the network have an inherent ability to consume radical oxygen to create sulfoxide and sulfone groups. These unique properties of thiol-ene networks make them a promising candidate as bone grafts for diabetic patients. In this work, we propose a thiol-ene biomaterial to address the current limitations of MPJ fusion in diabetics by characterizing mechanical properties, degradation rates under accelerated conditions, and oxidative responsiveness under pathophysiologic conditions. We also demonstrated that thiol-ene-based materials could reduce the number of hydroxyl radicals associated with neuropathic comorbidities.

Antioxidant Supplementation Hinders the Role of Exercise Training as a Natural Activator of SIRT1

Exercise training (ET) is a natural activator of silent mating type information regulation 2 homolog 1 (SIRT1), a stress-sensor able to increase the endogenous antioxidant system. SIRT1 activators include polyphenols and vitamins, the antioxidant properties of which are well-known. Antioxidant supplements are used to improve athletic performance. However, they might blunt ET-related benefits. Middle-distance runners (MDR) taking (MDR-S) or not taking antioxidant supplements (MDR-NoS) were compared with each other and with sedentary subjects (CTR) to evaluate the ET effects on SIRT1 levels and oxidative stress, and to investigate whether an exogenous source of antioxidants could interfere with such effects. Thirty-two MDR and 14 CTR were enrolled. MDR-S took 240 mg vitamin C and 15 mg vitamin E together with mineral salts. SIRT1 mRNA and activity were measured in PBMCs. Total oxidative status (TOS) and total antioxidant capacity (TEAC) were determined in plasma. MDR showed higher levels of SIRT1 mRNA (p = 0.0387) and activity (p = 0.0055) than did CTR. MDR-NoS also showed higher levels than did MDR-S without reaching statistical significance. SIRT1 activity was higher (p = 0.0012) in MDR-NoS (1909 ± 626) than in MDR-S (1276 ± 474). TOS did not differ among the groups, while MDR showed higher TEAC levels than did CTR (2866 ± 581 vs. 2082 ± 560, p = 0.0001) as did MDR-S (2784 ± 643) and MDR-NoS (2919 ± 551) (MDR-S vs. CTR, p = 0.0007 and MDR-NoS vs. CTR, p = 0.003). TEAC (β = 0.4488356, 95% CI 0.2074645 0.6902067; p < 0.0001) and the MDR-NoS group (β = 744.6433, 95% CI 169.9954 1319.291; p= 0.012) predicted SIRT1 activity levels. Antioxidant supplementation seems to hinder the role of ET as a natural activator of SIRT1.

Effects of Red-Fleshed Pitaya (Selenicereus polyrhizus) Ingestion after Strenuous Exercise on Creatine Kinase and Mitochondrial Function in Rat Muscle Cells

BACKGROUND: Free radicals formed during strenuous exercise through an increase in reactive oxygen species induce damage to tissues (e.g., muscle and liver) and cause oxidative damage to cells, resulting in mitochondrial dysfunction. AIM: As an effective method to repair mitochondrial muscle cell function, this study investigated the effects of red-fleshed pitaya (RFP) ingestion on creatine kinase (CK), which is a biomarker for muscle tissue damage, and malondialdehyde (MDA) levels during strenuous exercise. METHODS: This study involved 25 3-month-old male rats with an average weight of 200 g. The RFP extract was obtained through ethanol extraction and concentrated using an air-drying method. Rats were randomly allocated into five groups as follows: Two control groups (K1 [no-exercise, no RFP] and K2 [exercise, no RFP]) and three test groups (P1, P2, and P3; subjected to exercise and treated with 75, 150, and 300 mg kg−1 body weight of RFP, respectively). The exercise was in the form of swimming for 20 min 3 times/week for 31 days. CK and MDA were measured through an enzyme-linked immunosorbent assay, and histopathological examinations were performed through hematoxylin and eosin staining of rat muscles. RESULTS: The MDA levels after the ingestion of RFP extracts were compared between the K2 group and the P1, P2, and P3 groups. The results showed significant differences (p < 0.05 for P1 and P2, and p < 0.01 for P3), indicating the production of free radicals and CK, with features of damaged muscle cells based on histopathology. Ingestion of the RFP extract led to improvements in soleus muscle cells, resulting in cell function repair. CONCLUSION: Levels of MDA and CK increased during exercise, which caused significant muscle damage. However, after treatment with the RFP extract, the levels of both markers decreased. Thus, strenuous exercise causes an increase in reactive oxygen species, resulting in increased free radical levels. RFP ingestion decreased oxidative stress levels, thus repairing mitochondrial cell function.

Oxidative stress biomarkers and free amino acid concentrations in the blood plasma of moderately exercised horses indicate adaptive response to prolonged exercise training

Oxidative stress caused by routine physical stressors may negatively impact the performance of equine athletes; thus, the present study identifies oxidative biomarkers in the blood plasma of exercising horses. Stock-type horses were subject to a standardized moderate-intensity exercise protocol 3 times per week for 8 wk. Exercise protocol followed NRC guidelines consisting of 30% walk, 55% trot, and 15% canter, with a target heart rate (HR) of 90 BPM. Blood plasma was collected in wk 1, 2, 7, and 8 immediately before and 0, 30, 60, and 90 min after exercise and analyzed for total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Data were analyzed as repeated measures with wk, d, time, and their interactions as fixed effects. The TAC on day 2 (0.40 mM Trolox) was 7.5% greater than on day 3 (P = 0.013). There were wk × d × time interactions for SOD, TBARS, and GPx (P < 0.001). The TBARS remained at pre-exercise baseline (d-1 wk-1; 2.7 µM malondialdehyde) for most collection times within weeks 1, 7, and 8 (P ≥ 0.058); however, TBARS increased by 0.24 to 0.41 µM on day 2 of week 2 post-exercise (P < 0.001) and remained similarly elevated on day 3 pre- and immediately post-exercise (P < 0.001). The GPx similarly remained at baseline (172.6 µM/min; P ≥ 0.621) but increased by 48.18 to 83.4 µM/min at most collection times on days 1 and 2 of week 2 (P ≤ 0.023). The SOD remained at baseline (167.2 U/ mL; P ≥ 0.055) until increasing by 11.28 to 15.61 U/mL at 30 min post-exercise on day 1, week 1 and at most collection times on day 3, week 8 (P ≤ 0.043). Amino acids with antioxidant properties such as Met, Tyr, and Trp drastically decreased from weeks 2 to 8 (P < 0.001). Met and Tyr also decreased from -60 to 90 min (P < 0.047), whereas there was no time effect on Trp concentration (P = 0.841). The current study indicates the time-dependent nature of oxidative stress concerning persistent stressors such as exercise.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

Mechanistic Insight into Oxidative Stress-Triggered Signaling Pathways and Type 2 Diabetes

Oxidative stress (OS) is a metabolic dysfunction mediated by the imbalance between the biochemical processes leading to elevated production of reactive oxygen species (ROS) and the antioxidant defense system of the body. It has a ubiquitous role in the development of numerous noncommunicable maladies including cardiovascular diseases, cancers, neurodegenerative diseases, aging and respiratory diseases. Diseases associated with metabolic dysfunction may be influenced by changes in the redox balance. Lately, there has been increasing awareness and evidence that diabetes mellitus (DM), particularly type 2 diabetes, is significantly modulated by oxidative stress. DM is a state of impaired metabolism characterized by hyperglycemia, resulting from defects in insulin secretion or action, or both. ROS such as hydrogen peroxide and the superoxide anion introduce chemical changes virtually in all cellular components, causing deleterious effects on the islets of β-cells, in turn affecting insulin production. Under hyperglycemic conditions, various signaling pathways such as nuclear factor-κβ (NF-κβ) and protein kinase C (PKC) are also activated by ROS. All of these can be linked to a hindrance in insulin signaling pathways, leading to insulin resistance. Hyperglycemia-induced oxidative stress plays a substantial role in complications including diabetic nephropathy. DM patients are more prone to microvascular as well as atherosclerotic macrovascular diseases. This systemic disease affects most countries around the world, owing to population explosion, aging, urbanization, obesity, lifestyle, etc. However, some modulators, with their free radical scavenging properties, can play a prospective role in overcoming the debilitating effects of OS. This review is a modest approach to summarizing the basics and interlinkages of oxidative stress, its modulators and diabetes mellitus. It may add to the understanding of and insight into the pathophysiology of diabetes and the crucial role of antioxidants to weaken the complications and morbidity resulting from this chronic disease.

The effects of regular swimming exercise during sodium valproate treatment on seizure behaviors and EEG recordings in pentylenetetrazole-kindled rats

We investigated the effects of alone/combined regular swimming exercise and sodium valproate on epileptic seizure behaviors and EEG recordings, anti-oxidative mechanism, learning, and memory in pentylenetetrazole (PTZ)-kindled rats. Forty-eight healthy rats were randomly divided into eight equal groups as control (CONT), swimming exercise (EX), sodium valproate (SV), SV+EX, PTZ, EX+PTZ, SV+PTZ and SV+EX+PTZ. The rats were forced to regular swimming exercise for 60 min every other day, 13 doses of PTZ (40 mg/kg) were given to induce epileptic seizures and 200 mg/kg SV was given for 28 days. Epileptic seizures were evaluated by visual observation and EEG recordings (total spike numbers and number of epileptiform discharges). Memory and learning skills were assessed with passive avoidance test. According to our visual seizure observations, seizure latency was prolonged only in SV+EX+PTZ (p < 0.001) group, seizure severity score decreased in SV+PTZ (p < 0.05) and SV+EX+PTZ (p < 0.001) groups and seizure frequency was reduced in SV+PTZ (p < 0,001), EX+PTZ (p < 0,001), and SV+EX+PTZ (p < 0,001) groups. Total spike numbers and number of epileptiform discharges highly increased in PTZ group, whereas they decreased in swimming exercise and/or SV treatment groups. The most effective result was seen in the combined therapy group. Memory deficit was observed in PTZ -kindling group, but it didn't change with exercise or SV. Based on our results, regular swimming exercise had positive effects on PTZ-induced seizure frequency, and combined therapy of regular swimming exercise and SV is the most effective way to ameliorate visual seizure behaviors and decrease spike numbers and number of epileptiform discharges according to EEG recordings. Regular swimming exercise could be an alternative option to reduce the dose of SV and the side effects of SV can be avoided in clinical aspects.

Sirtuins and Renal Oxidative Stress

Renal failure is a major health problem that is increasing worldwide. To improve clinical outcomes, we need to understand the basic mechanisms of kidney disease. Aging is a risk factor for the development and progression of kidney disease. Cells develop an imbalance of oxidants and antioxidants as they age, resulting in oxidative stress and the development of kidney damage. Calorie restriction (CR) is recognized as a dietary approach that promotes longevity, reduces oxidative stress, and delays the onset of age-related diseases. Sirtuins, a type of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, are considered to be anti-aging molecules, and CR induces their expression. The sirtuin family consists of seven enzymes (Sirt1–7) that are involved in processes and functions related to antioxidant and oxidative stress, such as DNA damage repair and metabolism through histone and protein deacetylation. In fact, a role for sirtuins in the regulation of antioxidants and redox substances has been suggested. Therefore, the activation of sirtuins in the kidney may represent a novel therapeutic strategy to enhancing resistance to many causative factors in kidney disease through the reduction of oxidative stress. In this review, we discuss the relationship between sirtuins and oxidative stress in renal disease.

Protective effects of molecular hydrogen on lung injury from lung transplantation

Lung grafts may experience multiple injuries during lung transplantation, such as warm ischaemia, cold ischaemia, and reperfusion injury. These injuries all contribute to primary graft dysfunction, which is a major cause of morbidity and mortality after lung transplantation. As a potential selective antioxidant, hydrogen molecule (H₂) protects against post-transplant complications in animal models of multiple organ transplantation. Herein, the authors review the current literature regarding the effects of H₂ on lung injury from lung transplantation. The reviewed studies showed that H₂ improved the outcomes of lung transplantation by decreasing oxidative stress and inflammation at the donor and recipient phases. H₂ is primarily administered via inhalation, drinking hydrogen-rich water, hydrogen-rich saline injection, or a hydrogen-rich water bath. H₂ favorably modulates signal transduction and gene expression, resulting in the suppression of pro-inflammatory cytokines and excess reactive oxygen species production. Although H₂ appears to be a physiological regulatory molecule with antioxidant, anti-inflammatory and anti-apoptotic properties, its exact mechanisms of action remain elusive. Taken together, accumulating experimental evidence indicates that H₂ can significantly alleviate transplantation-related lung injury, mainly via inhibition of inflammatory cytokine secretion and reduction in oxidative stress through several underlying mechanisms. Further animal experiments and preliminary human clinical trials will lay the foundation for the use of H₂ as a treatment in the clinic.

Exercise intervention under hypoxic condition as a new therapeutic paradigm for type 2 diabetes mellitus: A narrative review

This review aims to summarize the health benefits of exposure to hypoxic conditions during exercise in patients with type 2 diabetes mellitus (T2DM). Exposure to hypoxic conditions during exercise training positively changes the physiological response in healthy subjects. Exposure to hypoxic conditions during exercise could markedly increase skeletal muscle glucose uptake compared to that in normoxic conditions. Furthermore, post-exercise insulin sensitivity of T2DM patients increases more when exercising under hypoxic than under normoxic conditions. Regular exercise under short-term hypoxic conditions can improve blood glucose control at lower workloads than in normoxic conditions. Additionally, exercise training under short-term hypoxic conditions can maximize weight loss in overweight and obese patients. Previous studies on healthy subjects have reported that regular exercise under hypoxic conditions had a more positive effect on vascular health than exercising under normoxic conditions. However, currently, evidence indicating that exposure to hypoxic conditions could positively affect T2DM patients in the long-term is lacking. Therefore, further evaluations of the beneficial effects of exercise under hypoxic conditions on the human body, considering different cycle lengths, duration of exposures, sessions per day, and the number of days, are necessary. In this review, we conclude that there is evidence that exercise under hypoxic conditions can yield health benefits, which is potentially valuable in terms of clinical care as a new intervention for T2DM patients.

Potentiality of ghrelin as antioxidant and protective agent

Background

Oxidative stress is the result of cellular troubles related to aerobic metabolism. Furthermore, this stress is always associated with biological responses evoked by physical, chemical, environmental, and psychological factors. Several studies have developed many approaches of antioxidant defense to diminish the severity of many diseases. Ghrelin was originally identified from the rat stomach, and it is a potent growth hormone-releasing peptide that has pleiotropic functions.

Methods

A systematic review was conducted within PubMed, ScienceDirect, MEDLINE, and Scopus databases using keywords such as ghrelin, antioxidant, oxidative stress, and systemic oxidative stress sensor.

Results

In the last decade, many studies show that ghrelin exhibits protection effects against oxidative stress derived probably from its antioxidant effects. Pieces of evidence demonstrate that systemic oxidative stress increase ghrelin levels in the plasma. The expression of ghrelin and its receptor in ghrelin peripheral tissues and extensively in the central nervous system suggests that this endogenous peptide plays an important role as a systemic oxidative stress sensor

Conclusion

The current evidence confirms that ghrelin and its derived peptides (Desacyl-ghrelin, obestatin) act as a protective antioxidant agent. Therefore, stressor modality, duration, and intensity are the parameters of oxidative stress that must be taken into consideration to determine the role of ghrelin, Desacyl-ghrelin, and obestatin in the regulation of cell death pathways.

Running to Lower Resting Blood Pressure: A Systematic Review and Meta-analysis

BACKGROUND

According to previous epidemiological studies, there are pros and cons for the relationship between running regularly and changes in resting blood pressure (RBP), and the changes may depend on the form of exercise.

OBJECTIVE

The aims of the current systematic review were to summarize the effects of running regularly on RBP and to investigate the most efficacious form of running in reducing RBP for this purpose.

METHODS

The inclusion criteria were: randomized controlled trials, involving healthy adults or adults with hypertension, the exercise group only performed regular running and the control group did not exercise, and the study reported the mean resting systolic blood pressure (RSBP) and/or diastolic blood pressure (RDBP). The mean difference (MD) in RBP in each trial was defined as follows: (mean value at post-intervention in the exercise group - mean value at baseline in the exercise group) - (mean value at post-intervention in the control group - mean value at baseline in the control group) and was calculated. The weighted MD (WMD) was defined as the synthesis of all MD. A linear meta-regression analysis, exercise intensity [the percentage of maximum heart rate] (%) and total exercise time throughout the intervention (hours) were selected as explanatory variables and the MD in RBP served as the objective variable.

RESULTS

Twenty-two trials (736 subjects) were analyzed. When trials were limited to those involving healthy subjects, the WMD in RBP decreased significantly [RSBP: - 4.2 mmHg (95% confidence intervals (95% CI) - 5.9 to - 2.4); RDBP: - 2.7 mmHg (95% CI - 4.2 to - 1.1)] and did not contain significant heterogeneity (RSBP: P = 0.67, I² = 0.0%; DBP: P = 0.38, I² = 7.2%). When trials were limited to those involving subjects with hypertension, the WMD in RBP decreased significantly [RSBP: - 5.6 mmHg (95% CI - 9.1 to - 2.1); RDBP: - 5.2 mmHg (95% CI - 9.0 to - 1.4)] but contained significant heterogeneity (RSBP: P = 0.01, I² = 62.2%; DBP: P < 0.01, I² = 87.7) and a meta-regression analysis showed that the percentage of maximum heart rate was significantly associated with the WMD in RSBP [slope: 0.56 (95% CI 0.21 to 0.92), intercept: - 48.76 (95% CI - 76.30 to - 21.22), R² = 0.88] and RDBP [slope: 0.45 (95% CI 0.01 to 0.87), intercept: - 38.06 (95% CI - 72.30 to - 4.08), R² = 0.41]. When trials were limited to those involving subjects with hypertension and a mean age ≥ 40 years, a meta-regression analysis showed that total exercise time throughout the intervention was significantly associated with the WMD in RDBP [slope: 0.82 (95% CI 0.54 to 1.09), intercept: - 22.90 (95% CI - 29.04 to - 16.77), R² = 0.99].

CONCLUSIONS

Running regularly decreases RBP, but the changes in subjects with hypertension may differ depending on exercise intensity or total exercise time. Therefore, running regularly at moderate intensity and at a restrained volume is recommended to lower RBP in subjects with hypertension.

Effect of Tai Chi on Markers of Oxidative Stress: Systematic Review and Meta-Analysis

Background: This study aimed to synthesize the evidence of the effect of practicing Tai Chi on oxidative stress markers (OxSM). Methods: This systematic review and meta-analysis was conducting using the MEDLINE, Cochrane Library, ScienceDirect, Scopus, Epistemonikos, Lilacs, and Ovid databases to identify randomized (RCT) and non-randomized (NRCT) clinical trials that evaluated the Tai Chi effect on OxSM compared to sedentary behavior, walking or yoga. Pooled mean differences (MDs) with 95% confidence intervals (95%CI) were estimated using the inverse variance method to determine the effect of Tai Chi on OxSM. PROSPERO register: CRD42019138362. Results: Five RCT and five NRCT were included. Compared to sedentary behavior, regular Tai Chi practice increases the levels of the enzymes superoxide dismutase (MD = 34.97 U/mL, (95%CI, 9.45 to 60.48), 344 participants) and catalase (MD = 15.63 U/mL, (95%CI, 4.05 to 27.22), 110 participants), as well as reducing the levels of lipoperoxides (MD = −0.02 µmol/L, (95%CI, −0.04 to −0.00), 234 participants). For comparisons with walking or yoga, only one study per activity was identified comparing the effect on OxSM. Conclusions: Regular Tai Chi practice increases the levels of superoxide dismutase and catalase, as well as reducing the levels of lipoperoxides. More studies are necessary to determine the effect of Tai Chi on OxSM when compared to other physical activities.

Swimming training mitigates the sex-specific hepatic disruption caused by a high-calorie diet: The putative modulation of Nrf2/Keap-1 pathway in male mice

This study investigated whether swimming protocol induces adaptations to sex-specific oxidative stress and Nrf2/Keap-1 pathway in the liver of mice fed a high-calorie diet (HCD) during the early life period. Male and female Swiss mice were fed a standard or high-calorie (enriched with 20% lard and 20% corn syrup) diets, and the trained mice were subjected to a swimming protocol (5 days/week) from 21^st to 49^th postnatal days. Males fed a HCD had more pronounced alterations in all parameters evaluated than females. Although there was no increase in body weight, the fat deposition was higher in male mice exposed to diet. The intake of HCD induced dyslipidemia mainly in males. In a sex-dependent manner, the hepatic markers of oxidative damage, antioxidant defences, and a sensitive sulfhydryl protein were altered in mice fed a HCD. Swimming counteracted dyslipidemia, hepatic oxidative stress, and the Nrf2/Keap-1 signalling downregulation, in a sex-dependent manner, in mice exposed to a HCD. These findings demonstrate that a non-pharmacological therapy, swimming protocol, contributed to adaptations of sex-specific hepatic oxidative stress and Nrf2/Keap-1 regulation in male mice fed a HCD.

Research progress in the pathogenic mechanisms and imaging of severe frostbite

PURPOSE

This article reviews the pathological mechanisms and progress of imaging of severe frostbite to assist in the search for targets for clinical diagnosis and treatment of severe frostbite. This review also aims to provide strong evidence for clinical diagnosis and treatment of deep frostbite.

METHODS

The review was based on the summary and analysis of the existing literature, and explored the pathological mechanism of deep frostbite and the advantages and disadvantages of imaging diagnostic methods.

RESULTS

According to the depth of tissue involvement, frostbite is divided into 4 levels. Severe frostbite includes Grade 3 and Grade 4 frostbite. Clinical performance evaluation and imaging diagnostic research have always been the mainstream of severe frostbite diagnosis. Imaging methods focus on vascular patency and tissue vitality. This article introduces angiography, SETCT/CT and MRA, and we summarize the advantages and disadvantages of these imaging methods. We recommend corresponding imaging modalities according to the state of frostbite patients.

CONCLUSIONS

Imaging examination, especially angiography and bone scans, provide useful information for determining the diagnosis and prognosis of severe frostbite. In order to obtain a good clinical prognosis, clinicians should first perform SPECT/CT. MRA does not burden the patient's body, but the balance between cost and benefit must be considered. Angiography provides a good feedback on the changes in blood vessel status before and after treatment, which is helpful for discovering the response of limbs to treatment.

Swimming Program on Mildly Diabetic Rats in Pregnancy

The present study aims to confirm if the moderate-intensity swimming has successful glycemic control and non-toxic oxidative stress levels and to verify the influence on pancreatic adaptations, embryo implantation, and placental efficiency. Female Wistar rats were randomly distributed to obtain mildly diabetic by streptozotocin induction at birth and the non-diabetic females given vehicle. At adulthood, pregnant rats were put at random into sedentary non-diabetic rats (ND); exercise non-diabetic rats (NDEx); sedentary diabetic rats (D); and exercise diabetic rats (DEx). The rats of the groups submitted to moderate intensity carried loads equivalent to 4% of body weight. On day 17 of gestational day, all rats were submitted to oral glucose tolerance test (OGTT). Next day (GD18), the rats were anesthetized and killed to count implantation sites and to collect placentas, blood, and muscle samples for biochemical biomarkers and pancreas for immunohistochemical analysis. The moderate exercise used was not sufficient to stimulate the aerobic pathway but presented positive results on glucose metabolism, lower embryo postimplantation loss, and pancreatic morphology compared with the sedentary diabetic group. However, the DEx group showed muscular damage, decreased antioxidant defense, and lipid peroxidation. Thus, the moderate-intensity exercise reduces glycemic levels during OGTT and causes no damage to non-diabetic rats related to other analyzed parameters in this study. The exercised diabetic rats present better glycemic metabolism in OGTT, islet pancreatic morphology, and embryofetal development. However, it is necessary an adjustment in this exercise intensity to improve the effectiveness of aerobic training for reduction of maternal muscular and lipid membrane damages.

The Role of Vitamin C in Two Distinct Physiological States: Physical Activity and Sleep

This paper is a literature overview of the complex relationship between vitamin C and two opposing physiological states, physical activity and sleep. The evidence suggests a clinically important bidirectional association between these two phenomena mediated by different physiological mechanisms. With this in mind, and knowing that both states share a connection with oxidative stress, we discuss the existing body of evidence to answer the question of whether vitamin C supplementation can be beneficial in the context of sleep health and key aspects of physical activity, such as performance, metabolic changes, and antioxidant function. We analyze the effect of ascorbic acid on the main sleep components, sleep duration and quality, focusing on the most common disorders: insomnia, obstructive sleep apnea, and restless legs syndrome. Deeper understanding of those interactions has implications for both public health and clinical practice.

Effects of Short-Term Green Tea Extract Supplementation on VO2 Max and Inflammatory and Antioxidant Responses of Healthy Young Men in a Hot Environment

Background:

Nowadays, the use of green tea supplements has increased. Studies have shown that green tea can have positive effects on anti-inflammatory and antioxidative factors, as well as improve aerobic performance capacity. Therefore, in this study, we investigate the effects of this supplement on inflammatory factors, total antioxidant capacity responses, and maximum oxygen uptake (VO₂ Max) of healthy young men in summer.

Methods:

This study is a double-blind randomized controlled trial (RCT) in which 15 young men (age 25.06 ± 2.1) were randomly assigned into the green tea (GT) and placebo groups. Subjects performed maximum aerobic exercises (shuttle run 20 m) in separate workouts (14 days) in summer. They consumed 640 mg green tea extracts or maltodextrin 90 min before exercise in a double-blind design. Blood samples were collected before and after the exercise and then evaluated in the biochemistry laboratory. In this study, one way analysis of variance (ANOVA) tests were used for the statistical analysis.

Results:

The results of this study show that green tea supplement significantly slowed down the increasing tumor necrosis factor alpha (TNF-α) (GT: 15.03 ± 4.31 [pg/ml], placebo: 31.38 ± 7.18 [pg/ml], [P = 0.000]); increased the total antioxidant capacity (GT: 1.04 ± 0.06 [mm], placebo group: 0.72 ± 0.04 [mm], [P = 0.001 VO₂]); and Max (GT: 44.43 ± 3.06 [ml/kg/min], placebo group: 34.88 ± 1.30 [ml/kg/min], [P = 0.001]) in the supplement group than placebo. In addition, no significant differences in interleukin 1 beta (IL-1β) was observed between thee groups (GT: 26.86 ± 5.05 [pg/ml], placebo group: 23.47 ± 3.16 [pg/ml], [P = 0.251]).

Conclusions:

The consumption of green tea supplements 90 min before aerobic exercise may decrease inflammation and oxidative stress factors and improve VO₂ Max in summer.

Combined anthocyanins and bromelain supplement improves endothelial function and skeletal muscle oxygenation status in adults: a double-blind placebo-controlled randomised crossover clinical trial

Anthocyanins and bromelain have gained significant attention due to their antioxidative and anti-inflammatory properties. Both have been shown to improve endothelial function, blood pressure (BP) and oxygen utility capacity in humans; however, the combination of these two and the impacts on endothelial function, BP, total antioxidant capacity (TAC) and oxygen utility capacity have not been previously investigated. The purpose of this study was to investigate the impacts of a combined anthocyanins and bromelain supplement (BE) on endothelial function, BP, TAC, oxygen utility capacity and fatigability in healthy adults. Healthy adults (n 18, age 24 (sd 4) years) received BE or placebo in a randomised crossover design. Brachial artery flow-mediated dilation (FMD), BP, TAC, resting heart rate, oxygen utility capacity and fatigability were measured pre- and post-BE and placebo intake. The BE group showed significantly increased FMD, reduced systolic BP and improved oxygen utility capacity compared with the placebo group (P < 0·05). Tissue saturation and oxygenated Hb significantly increased following BE intake, while deoxygenated Hb significantly decreased (P < 0·05) during exercise. Additionally, TAC was significantly increased following BE intake (P < 0·05). There were no significant differences for resting heart rate, diastolic BP or fatigability index. These results suggest that BE intake is an effective nutritional therapy for improving endothelial function, BP, TAC and oxygen utility capacity, which may be beneficial to support vascular health in humans.

Total Dietary Antioxidant Intake Including Polyphenol Content: Is it Capable to Fight against Increased Oxidants within the Body of Ultra-Endurance Athletes?

The role of dietary antioxidants on exhaustive exercise-induced oxidative stress has been well investigated. However, the contribution of total dietary antioxidant capacity on exogenous antioxidant defense and exercise performance has commonly been disregarded. The aims of the present investigation were to examine (i) the effects of dietary total antioxidant intake on body antioxidant mechanisms, and (ii) an exhaustive exercise-induced oxidative damage in ultra-endurance athletes. The study included 24 ultra-marathon runners and long-distance triathletes (12 male and 12 female) who underwent an acute exhaustive exercise test (a cycle ergometer (45 min at 65% VO₂max) immediately followed by a treadmill test (75% VO₂max to exhaustion). Oxidative stress-related biomarkers (8-isoprostaglandin F2alpha (8-iso PGF2a), total oxidant status (TOS, total antioxidant status (TAS)) in plasma were collected before and after exercise. Oxidative stress index was calculated to assess the aspect of redox balance. Blood lactate concentrations and heart rate were measured at the 3rd and 6th min after exercise. Dietary antioxidant intake was calculated using the ferric reducing ability of plasma (FRAP) assay. Dietary total antioxidant intake of the subjects was negatively correlated with pre-exercise TOS concentrations (rs = -0.641 in male, and rs = -0.741 in females) and post- vs. pre- (∆) 8-iso PGF2a levels (rs = -0.702 in male; p = 0.016, and rs = -0.682 in females; p = 0.024), and positively correlated with ∆ TAS concentrations (rs = 0.893 in males; p = 0.001, and rs = 0.769 in females; p = 0.002) and post- exercise lactate concentrations (rs = 0.795 for males; p = 0.006, and rs = 0.642 for females; p = 0.024). A positive meaningful (p = 0.013) interaction was observed between time at exhaustion and dietary antioxidant intake (rs = 0.692) in males, but not in females. In conclusion, the determination of total dietary antioxidant intake in ultra-endurance athletes may be crucial for gaining a better perspective on body antioxidant defense against exhaustive exercise-induced oxidative stress. However, the effects of dietary antioxidant on exercise performance and recovery rate needs further investigation.

ROS-associated immune response and metabolism: a mechanistic approach with implication of various diseases

The immune system plays a pivotal role in maintaining the defense mechanism against external agents and also internal danger signals. Metabolic programming of immune cells is required for functioning of different subsets of immune cells under different physiological conditions. The field of immunometabolism has gained ground because of its immense importance in coordination and balance of immune responses. Metabolism is very much related with production of energy and certain by-products. Reactive oxygen species (ROS) are generated as one of the by-products of various metabolic pathways. The amount, localization of ROS and redox status determine transcription of genes, and also influences the metabolism of immune cells. This review discusses ROS, metabolism of immune cells at different cellular conditions and sheds some light on how ROS might regulate immunometabolism.

DNA Damage Following Acute Aerobic Exercise: A Systematic Review and Meta-analysis

BACKGROUND

Exercise is widely recognised for its health enhancing benefits. Despite this, an overproduction of reactive oxygen and nitrogen species (RONS), outstripping antioxidant defence mechanisms, can lead to a state of (chronic) oxidative stress. DNA is a vulnerable target of RONS attack and, if left unrepaired, DNA damage may cause genetic instability.

OBJECTIVE

This meta-analysis aimed to systematically investigate and assess the overall effect of studies reporting DNA damage following acute aerobic exercise.

METHODS

Web of Science, PubMed, MEDLINE, EMBASE, and Scopus were searched until April 2019. Outcomes included (1) multiple time-points (TPs) of measuring DNA damage post-exercise, (2) two different quantification methods (comet assay and 8-oxo-2'-deoxyguanosine; 8-OHdG), and (3) protocols of high intensity (≥ 75% of maximum rate of oxygen consumption; VO2-max) and long distance (≥ 42 km).

RESULTS

Literature search identified 4316 non-duplicate records of which 35 studies were included in the meta-analysis. The evidence was strong, showcasing an increase in DNA damage immediately following acute aerobic exercise with a large-effect size at TP 0 (0 h) (SMD = 0.875; 95% CI 0.5, 1.25; p < 0.05). When comparing between comet assay and 8-OHdG at TP 0, a significant difference was observed only when using the comet assay. Finally, when isolating protocols of long-distance and high-intensity exercise, increased DNA damage was only observed in the latter. (SMD = 0.48; 95% CI - 0.16, 1.03; p = 0.15 and SMD = 1.18; 95% CI 0.71, 1.65; p < 0.05 respectively).

CONCLUSIONS

A substantial increase in DNA damage occurs immediately following acute aerobic exercise. This increase remains significant between 2 h and 1 day, but not within 5-28 days post-exercise. Such an increase was not observed in protocols of a long-distance. The relationship between exercise and DNA damage may be explained through the hormesis theory, which is somewhat one-dimensional, and thus limited. The hormesis theory describes how exercise modulates any advantageous or harmful effects mediated through RONS, by increasing DNA oxidation between the two end-points of the curve: physical inactivity and overtraining. We propose a more intricate approach to explain this relationship: a multi-dimensional model, to develop a better understanding of the complexity of the relationship between DNA integrity and exercise.

High intensity interval training and molecular adaptive response of skeletal muscle

Increased cardiovascular fitness, V˙O_2max, is associated with enhanced endurance capacity and a decreased rate of mortality. High intensity interval training (HIIT) is one of the best methods to increase V˙O_2max and endurance capacity for top athletes and for the general public as well. Because of the high intensity of this type of training, the adaptive response is not restricted to Type I fibers, as found for moderate intensity exercise of long duration. Even with a short exercise duration, HIIT can induce activation of AMPK, PGC-1α, SIRT1 and ROS pathway as well as by the modulation of Ca²⁺ homeostasis, leading to enhanced mitochondrial biogenesis, and angiogenesis. The present review summarizes the current knowledge of the adaptive response of HIIT.

Early-life N-arachidonoyl-dopamine exposure increases antioxidant capacity of the brain tissues and reduces functional deficits after neonatal hypoxia in rats

Perinatal hypoxia-ischemia is one of the most common causes of perinatal brain injury and subsequent neurological disorders in children. The aim of this work was to evaluate the potential antioxidant and neuroprotective effects of N-arachidonoyl-dopamine (NADA) in the model of acute neonatal hypoxia (ANH) in rat pups. Male and female Wistar rats were exposed to a hypoxic condition (8% oxygen for 120 min) at postnatal day 2 (P2). Transcription factor HIF1-α and glutathione peroxidases GPx2 and GPx4 gene expression was increased in rat brains in the hypoxic group compared to control 1.5 h but not 4 days after ANH. There were no post-hypoxic changes in reduced (GSH) and oxidised (GSSG) glutathione levels in the brain of rat pups 1.5 h and 4 d after hypoxia. Hypoxic rats displayed retarded performance in the righting reflex and the negative geotaxis tests. ANH resulted in increased ambulation in Open field test and impaired retention in the Barnes maze task under stressful conditions as compared with the control group. Treatment with NADA significantly attenuated the delayed development of sensorimotor reflexes and stress-evoked disruption of memory retention in hypoxic rats but had no effect on the hypoxia-induced hyperactivity. In rats exposed to hypoxia, treatment with NADA decreased GPx2 gene expression and increased GSH/GSSG ratio in whole brains 1.5 h after ANH. These results suggest that the long-lasting beneficial effects of NADA on hypoxia-induced neurobehavioural deficits are mediated, at least in part, by its antioxidant properties.

Pravastatin attenuates testicular damage induced by doxorubicin - a stereological and histopatological study

Background The aim of this study is to investigate the effects of pravastatin (PS) against doxorubicin (DOX)-induced testicular toxicity. Methods A total of 24 healthy male Sprague-Dawley rats were equally divided into four groups. Group I received normal saline, Group II received PS (20 mg/kg b.w.) by gavage, Group III was treated with DOX alone (15 mg/kg b.w., i.p.) and Group IV received the combination of DOX and PS. Results After 8 weeks, the results displayed that DOX caused a decrease in testicular volume and index, epididymal sperm count, seminiferous tubule diameter and germinal epithelium. DOX also reduced the number of spermatogonia, spermatoctyes and Sertoli cells as well as increased the lumen diameter of seminiferous tubules (p<0.05) and the incidence of histopathological changes of the testis. Moreover, elevated malondialdehyde (MDA) levels and declined glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were observed (p<0.05). On the contrary, PS treatment significantly ameliorated nearly all of these abnormalities (p<0.05). Conclusions PS protects against DOX-induced testicular toxicity in rats, which is likely via the inhibition of oxidative stress and the increase of antioxidant enzyme activity.

Oxidative stress in biological systems and its relation with pathophysiological functions: the effect of physical activity on cellular redox homeostasis

The body of evidence from the past three decades demonstrates that oxidative stress can be involved in several diseases. This study aims to summarise the current state of knowledge on the association between oxidative stress and the pathogenesis of some characteristic to the biological systems diseases and aging process. This review also presents the effect of physical activity on redox homeostasis. There is strong evidence from studies for participation of reactive oxygen and nitrogen species in pathogenesis of acute and chronic diseases based on animal models and human studies. Elevated levels of pro-oxidants and various markers of the oxidative stress and cells and tissues damage linked with pathogenesis of cancer, atherosclerosis, neurodegenerative diseases hypertension, diabetes mellitus, cardiovascular disease, atherosclerosis, reproductive system diseases, and aging were reported. Evidence confirmed that inflammation contributes widely to multiple chronic diseases and is closely linked with oxidative stress. Regular moderate physical activity regulates oxidative stress enhancing cellular antioxidant defence mechanisms, whereas acute exercise not preceded by training can alter cellular redox homeostasis towards higher level of oxidative stress. Future studies are needed to clarify the multifaceted effects of reactive oxygen/nitrogen species on cells and tissues and to continue study on the biochemical roles of antioxidants and physical activity in prevention of oxidative stress-related tissue injury.

The effects of Astragalus Membranaceus Active Extracts on Autophagy-related Diseases

Autophagy is an evolutionarily conserved 'self-eating' process that maintains cellular, tissue, and organismal homeostasis. New studies on autophagy, mediated by subsets of autophagy proteins, are emerging in many physiological and pathological processes. Astragalus membranaceus (AM), also named Huangqi, is one of the fundamental herbs in traditional Chinese medicine and its extracts have been proved to possess many biological activities related to autophagy, including anti-oxidation, anti-inflammation, anticancer, anti-photoaging, and improvement of cardiomyocyte function. Evidence suggests that AM extracts can have therapeutic potential in autophagy dysregulation-associated diseases because of their biological positive effects. Here we will review the literature concerning the effects of AM extracts on autophagy dysregulation-associated diseases.

Osteocyte viability and bone density in cadmium chloride-induced osteoporosis ameliorated with Pilostigma thonningii stem bark-extracted D-3-O-methy-chiroinositol

BACKGROUND

This study examined the ameliorative effect of D-3-O-methyl-chiroinositol, isolated from the stem bark of Piliostigma thonningii, on cadmium chloride-induced osteoporosis in male Wistar rats.

METHODS

Thirty-six rats were assigned to three treatment groups (n = 12). Group A (2 mL distilled water), group B: (2.5 mg/kg b.w. CdCl2) and group C: (2.5 mg/kg b.w. CdCl2 and D-3-O-methyl-chiroinositol 2 mg/kg b.w.). Bone ash, calcium, phosphate, magnesium, and zinc content, as well as bone histological changes were determined at the end of months 1, 2, and 3.

RESULTS

There were significant differences (P ≤ 0.05) in the weight of the cervical, tibia, and femoral bones in all groups. The serum concentration of CdCl2 was significantly different across the three groups with time. There was significant variation (P < 0.005) in the mean bone ash across groups. The concentration of OH-proline was significantly different (P < 0.0001) across groups. There were significant differences (P < 0.0001) in bone calcium, magnesium, zinc, and phosphorus concentrations. Histology revealed high levels of bone mineralisation in the CdCl2-treated group, indicative of osteoporosis with hypertrophied osteocytes, while the femur of Wistar rats treated with D-3-O-methyl-chiroinositol showed bone trabeculae and viable osteocytes.

CONCLUSION

The study concluded that D-3-O-methyl-chiroinositol extract from Piliostigma thionningii stem bark ameliorated cadmium chloride-induced osteoporosis in male Wistar rats.

Myocardial NADPH oxidase-4 regulates the physiological response to acute exercise

Regular exercise has widespread health benefits. Fundamental to these beneficial effects is the ability of the heart to intermittently and substantially increase its performance without incurring damage, but the underlying homeostatic mechanisms are unclear. We identify the ROS-generating NADPH oxidase-4 (Nox4) as an essential regulator of exercise performance in mice. Myocardial Nox4 levels increase during acute exercise and trigger activation of the transcription factor Nrf2, with the induction of multiple endogenous antioxidants. Cardiomyocyte-specific Nox4-deficient (csNox4KO) mice display a loss of exercise-induced Nrf2 activation, cardiac oxidative stress and reduced exercise performance. Cardiomyocyte-specific Nrf2-deficient (csNrf2KO) mice exhibit similar compromised exercise capacity, with mitochondrial and cardiac dysfunction. Supplementation with an Nrf2 activator or a mitochondria-targeted antioxidant effectively restores cardiac performance and exercise capacity in csNox4KO and csNrf2KO mice respectively. The Nox4/Nrf2 axis therefore drives a hormetic response that is required for optimal cardiac mitochondrial and contractile function during physiological exercise.

Investigation of reactive oxygen species produced by microwave electrodeless discharge lamp on oxidation of dimethyl sulfide

Microwave electrodeless discharge lamp (MEDL) has been regarded as a powerful light source of photoreaction. Four kinds of chemicals, nitrogen (N₂), oxygen (O₂), water (H₂O) and dimethyl sulfide (DMS), were used as molecular probes to explore the generation process of reactive oxygen species (ROS) and their photo-oxidation performances on the photodegradation of organic pollutants with application of an exterior MEDL system. ROS such as O (³P), O₃, O (¹D) and ¹O₂ were generated via irradiation of O₂ and H₂O except dry N₂ by MEDL. They were transformed to other ROS including ·OH and H₂O₂ with increase of relative humidity. The ROS productivity was inhibited evidently by humidity and ·OH became the major active species at high humidity. An optimal mineralization rate of 23.6% for DMS photodegradation was reached in dry air compared with 8.74% at high humidity, which indicated that O (¹D) and ¹O₂ were more powerful oxidants than O₃ and OH. The results showed that the higher mineralization rate of organic pollutants was obtained by increasing the generation efficiency of ROS of O (¹D) and ¹O₂. Furthermore, the results provided an alternative to develop intensification technology on photodegadation of organic pollutants with MEDL system and an optimal operation process including photocatalyst and humidity.

Adaptive homeostasis and the free radical theory of ageing

The Free Radical Theory of Ageing, was first proposed by Denham Harman in the mid-1950's, based largely on work conducted by Rebeca Gerschman and Daniel Gilbert. At its core, the Free Radical Theory of Ageing posits that free radical and related oxidants, from the environment and internal metabolism, cause damage to cellular constituents that, over time, result in an accumulation of structural and functional problems. Several variations on the original concept have been advanced over the past six decades, including the suggestion of a central role for mitochondria-derived reactive species, and the proposal of an age-related decline in the effectiveness of protein, lipid, and DNA repair systems. Such innovations have helped the Free Radical Theory of Aging to achieve widespread popularity. Nevertheless, an ever-growing number of apparent 'exceptions' to the Theory have seriously undermined its acceptance. In part, we suggest, this has resulted from a rather simplistic experimental approach of knocking-out, knocking-down, knocking-in, or overexpressing antioxidant-related genes to determine effects on lifespan. In some cases such experiments have yielded results that appear to support the Free Radical Theory of Aging, but there are just as many published papers that appear to contradict the Theory. We suggest that free radicals and related oxidants are but one subset of stressors with which all life forms must cope over their lifespans. Adaptive Homeostasis is the mechanism by which organisms dynamically expand or contract the homeostatic range of stress defense and repair systems, employing a veritable armory of signal transduction pathways (such as the Keap1-Nrf2 system) to generate a complex profile of inducible and enzymatic protection that best fits the particular need. Viewed as a component of Adaptive Homeostasis, the Free Radical Theory of Aging appears both viable and robust.

Hypoxia compounds exercise-induced free radical formation in humans; partitioning contributions from the cerebral and femoral circulation

This study examined to what extent the human cerebral and femoral circulation contribute to free radical formation during basal and exercise-induced responses to hypoxia. Healthy participants (5♂, 5♀) were randomly assigned single-blinded to normoxic (21% O₂) and hypoxic (10% O₂) trials with measurements taken at rest and 30 min after cycling at 70% of maximal power output in hypoxia and equivalent relative and absolute intensities in normoxia. Blood was sampled from the brachial artery (a), internal jugular and femoral veins (v) for non-enzymatic antioxidants (HPLC), ascorbate radical (A^•-, electron paramagnetic resonance spectroscopy), lipid hydroperoxides (LOOH) and low density lipoprotein (LDL) oxidation (spectrophotometry). Cerebral and femoral venous blood flow was evaluated by transcranial Doppler ultrasound (CBF) and constant infusion thermodilution (FBF). With 3 participants lost to follow up (final n = 4♂, 3♀), hypoxia increased CBF and FBF (P = 0.041 vs. normoxia) with further elevations in FBF during exercise (P = 0.002 vs. rest). Cerebral and femoral ascorbate and α-tocopherol consumption (v < a) was accompanied by A^•-/LOOH formation (v > a) and increased LDL oxidation during hypoxia (P < 0.043-0.049 vs. normoxia) implying free radical-mediated lipid peroxidation subsequent to inadequate antioxidant defense. This was pronounced during exercise across the femoral circulation in proportion to the increase in local O₂ uptake (r = -0.397 to -0.459, P = 0.037-0.045) but unrelated to any reduction in PO₂. These findings highlight considerable regional heterogeneity in the oxidative stress response to hypoxia that may be more attributable to local differences in O₂ flux than to O₂ tension.

Cardiovascular Adaptive Homeostasis in Exercise

Adaptive Homeostasis has been defined as, "The transient expansion or contraction of the homeostatic range in response to exposure to sub-toxic, non-damaging, signaling molecules or events, or the removal or cessation of such molecules or events." (Davies, 2016). I propose that one of the most significant examples of adaptive homeostasis may be the adaptation of the cardiovascular system to exercise training. In particular, endurance type training involves the generation of increased levels of free radicals such as ubisemiquinone, superoxide, nitric oxide, and other (non-radical) reactive oxygen species such as hydrogen peroxide (H2O2), in a repetitive manner, typically several times per week. As long as the training intensity and duration are sub-maximal and not exhaustive these reactive species do not cause damage, but rather activate signal transduction pathways to induce mitochondrial biogenesis-the foundation of increased exercise endurance. Particularly important are the NFκB and Nrf2 signal transduction pathways which respond to reactive oxygen and nitrogen species generated during exercise. As with other examples of adaptive homeostasis the effects are transient, lasting only as long as the training is maintained. Unfortunately, the ability to adapt to exercise training declines with age, perhaps as a result of impaired Nrf2 and NFκB signaling, as does adaptive homeostasis capacity in general. Since this is an Hypothesis/Theory Paper and not a review, I have not tried to provide a comprehensive discussion of all the literature relating to exercise adaptation and the cardiovascular system. Rather, I have attempted to develop the Hypothesis or Theory that adaptive homeostasis is the foundation for adaptation of the cardiovascular system to exercise training, largely based on work from my own laboratory, that of close collaborators, and that of key contributors over a period of almost 40 years.

Immune cell response to strenuous resistive breathing: comparison with whole body exercise and the effects of antioxidants

Background/hypothesis

Whole body exercise (WBE) changes lymphocyte subset percentages in peripheral blood. Resistive breathing, a hallmark of diseases of airway obstruction, is a form of exercise for the inspiratory muscles. Strenuous muscle contractions induce oxidative stress that may mediate immune alterations following exercise. We hypothesized that inspiratory resistive breathing (IRB) alters peripheral blood lymphocyte subsets and that oxidative stress mediates lymphocyte subpopulation alterations following both WBE and IRB.

Patients and methods

Six healthy nonathletes performed two WBE and two IRB sessions for 45 minutes at 70% of VO₂ maximum and 70% of maximum inspiratory pressure (Pi_max), respectively, before and after the administration of antioxidants (vitamins E, A, and C for 75 days, allopurinol for 30 days, and N-acetylcysteine for 3 days). Blood was drawn at baseline, at the end of each session, and 2 hours into recovery. Lymphocyte subsets were determined by flow cytometry.

Results

Before antioxidant supplementation at both WBE end and IRB end, the natural killer cell percentage increased, the T helper cell (CD3+ CD4+) percentage was reduced, and the CD4/CD8 ratio was depressed, a response which was abolished by antioxidants only after IRB. Furthermore, at IRB end, antioxidants promoted CD8+ CD38+ and blunted cytotoxic T-cell percentage increase. CD8+ CD45RA+ cell percentage changes were blunted after antioxidant supplementation in both WBE and IRB.

Conclusion

We conclude that IRB produces (as WBE) changes in peripheral blood lymphocyte subsets and that oxidative stress is a major stimulus predominantly for IRB-induced lymphocyte subset alterations.

A pilot study to assess the effect of acute exercise on brain glutathione

The brain is highly susceptible to oxidative stress due to its high metabolic demand. Increased oxidative stress and depletion of glutathione (GSH) are observed with aging and many neurological diseases. Exercise training has the potential to reduce oxidative stress in the brain. In this study, nine healthy sedentary males (aged 25 ± 4 years) undertook a bout of continuous moderate intensity exercise and a high-intensity interval (HII) exercise bout on separate days. GSH concentration in the anterior cingulate was assessed by magnetic resonance spectroscopy (MRS) in four participants, before and after exercise. This was a pilot study to evaluate the ability of the MRS method to detect exercise-induced changes in brain GSH in humans for the first time. MRS is a non-invasive method based on nuclear magnetic resonance, which enables the quantification of metabolites, such as GSH, in the human brain in vivo. To add context to brain GSH data, other markers of oxidative stress were also assessed in the periphery (in blood) at three time points [pre-, immediately post-, and post (∼1 hour)-exercise]. Moderate exercise caused a significant decrease in brain GSH from 2.12 ± 0.64 mM/kg to 1.26 ± 0.36 mM/kg (p = .04). Blood GSH levels increased immediately post-HII exercise, 580 ± 101 µM to 692 ± 102 µM (n = 9, p = .006). The findings from this study show that brain GSH is altered in response to acute moderate exercise, suggesting that exercise may stimulate an adaptive response in the brain. Due to the challenges in MRS methodology, this pilot study should be followed up with a larger exercise intervention trial.

Dose and time effect of CdTe quantum dots on antioxidant capacities of the liver and kidneys in mice

Although quantum dot (QD)-induced toxicity occurs due to free radicals, generation of oxidative stress mediated by reactive oxygen species (ROS) formation is considered an important mechanism. However, free radical mechanisms are essentially difficult to elucidate at the molecular level because most biologically relevant free radicals are highly reactive and short-lived, making them difficult to directly detect, especially in vivo. Antioxidants play an important role in preventing or, in most cases, limiting the damage caused by ROS. Healthy people and animals possess many endogenous antioxidative substances that scavenge free radicals in vivo to maintain the redox balance and genome integrity. The antioxidant capacity of an organism is highly important but seldom studied. In this study, the dose and time effects of CdTe QDs on the antioxidant capacities of the liver and kidneys were investigated in mice using the electron paramagnetic resonance (EPR) spin-trapping technique. We found that the liver and kidneys of healthy mice contain specific antioxidant capacities that scavenge ·OH and ·O₂⁻. Furthermore, oxidative stress markers (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx], glutathione [GSH] and malondialdehyde [MDA]) were examined. In dose course studies, the free radical scavenging efficiencies of the liver and kidneys were found to gradually decrease with increasing concentration of CdTe QD exposure. The activities and levels of SOD, CAT, GPx and MDA were observed to increase in treated groups, whereas those of GSH were reduced. The time course studies revealed that the QD-induced antioxidant efficiency reduction was time dependent with GSH decrease and could recover after a period of time. These experimental results offer new information on QD toxicity in vivo. Specifically, CdTe QDs can deplete GSH to reduce the elimination ability of the liver and kidneys for ·OH and ·O₂⁻, thus inducing oxidative damage to tissues.

Ellagic acid and rosmarinic acid attenuate doxorubicin-induced testicular injury in rats

The anticancer drug doxorubicin causes testicular toxicity as an undesirable effect. The present study was undertaken to investigate the possible protection of ellagic acid and rosmarinic acid during doxorubicin administration. For this purpose eight groups of male Sprague-Dawley rats were used (n = 10), one group received vehicle served as control, and other groups received 5 mg/kg doxorubicin twice a week for 2 weeks for a cumulative dose of 20 mg/kg, ellagic acid (10 mg/kg/day, 14 consecutive days p.o.), rosmarinic acid (75 mg/kg/day, 14 consecutive days p.o.), ellagic acid and rosmarinic acid. The latter three regimens were given to control and doxorubicin-received rats. Doxorubicin decreased testicular relative weight, sperm count, motility, serum testosterone, testicular glycogen, and sialic acid with increased incidence of histopathological changes, oxidative stress, tumor necrosis factor-alpha, as well as cholinesterase activity. Conversely, ellagic and rosmarinic acid treatment ameliorated such damage, thus showing the possibility to use as an adjuvant during doxorubicin treatment.

Redox Control of Skeletal Muscle Regeneration

Skeletal muscle shows high plasticity in response to external demand. Moreover, adult skeletal muscle is capable of complete regeneration after injury, due to the properties of muscle stem cells (MuSCs), the satellite cells, which follow a tightly regulated myogenic program to generate both new myofibers and new MuSCs for further needs. Although reactive oxygen species (ROS) and reactive nitrogen species (RNS) have long been associated with skeletal muscle physiology, their implication in the cell and molecular processes at work during muscle regeneration is more recent. This review focuses on redox regulation during skeletal muscle regeneration. An overview of the basics of ROS/RNS and antioxidant chemistry and biology occurring in skeletal muscle is first provided. Then, the comprehensive knowledge on redox regulation of MuSCs and their surrounding cell partners (macrophages, endothelial cells) during skeletal muscle regeneration is presented in normal muscle and in specific physiological (exercise-induced muscle damage, aging) and pathological (muscular dystrophies) contexts. Recent advances in the comprehension of these processes has led to the development of therapeutic assays using antioxidant supplementation, which result in inconsistent efficiency, underlying the need for new tools that are aimed at precisely deciphering and targeting ROS networks. This review should provide an overall insight of the redox regulation of skeletal muscle regeneration while highlighting the limits of the use of nonspecific antioxidants to improve muscle function. Antioxid. Redox Signal. 27, 276-310.

Tissue-specific daily variation in the oxidative status of sturgeon (Acipenser naccarii) and rainbow trout (Oncorhynchus mykiss): a comparative study

The oxidative status is associated with animal lifespan, metabolism, activity and circadian rhythms. The objective of this work is to study the time course of the oxidative status over a daily cycle in the plasma, liver and brain, and the changes in the plasma cortisol levels of sturgeon and trout. The knowledge of daily oxidative status will provide a better understanding of the trout and sturgeon physiology and adequate maintenance and food supply of farmed fish in relation to photoperiod. Superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase activities, lipid peroxidation and cortisol were measured. Our results showed that the antioxidative enzyme activities and lipid peroxidation in the liver of trout and sturgeon changed through the day, with increased levels in lipid peroxidation of liver in the dark period for sturgeon. This could be related to the different activity time in both species, an issue to be taken into account when designing the guidelines of the maintenance of these species in fish farms. On the contrary, there was not clear influence of the daily rhythms on brain oxidative status. The higher efficiency of the antioxidant defences in the brain of sturgeon, which displays less lipid peroxidation and higher antioxidative activity, could be related to its longer life expectancy. The absence of any apparent daily rhythm in the plasma cortisol levels in sturgeon could indicate a lower susceptibility to stress, and that mechanisms involved in cortisol secretion in chondrosteans could be different from that described for teleosteans.