Effect of a single bout of exercise and beta-carotene supplementation on the urinary excretion of 8-hydroxy-deoxyguanosine in humans

Royal jelly plus coenzyme Q10 supplementation improves high-intensity interval exercise performance via changes in plasmatic and salivary biomarkers of oxidative stress and muscle damage in swimmers: a randomized, double-blind, placebo-controlled pilot trial

Background

Excessive production of free radicals caused by many types of exercise results in oxidative stress, which leads to muscle damage, fatigue, and impaired performance. Supplementation with royal jelly (RJ) or coenzyme Q10 (CoQ10) has been shown to attenuate exercise-induced oxidant stress in damaged muscle and improve various aspects of exercise performance in many but not all studies. Nevertheless, the effects of treatments based on RJ plus CoQ10 supplementation, which may be potentially beneficial for reducing oxidative stress and enhancing athletic performance, remain unexplored. This study aimed to examine whether oral RJ and CoQ10 co-supplementation could improve high-intensity interval exercise (HIIE) performance in swimmers, inhibiting exercise-induced oxidative stress and muscle damage.

Methods

Twenty high-level swimmers were randomly allocated to receive either 400 mg of RJ and 60 mg of CoQ10 (RJQ) or matching placebo (PLA) once daily for 10 days. Exercise performance was evaluated at baseline, and then reassessed at day 10 of intervention, using a HIIE protocol. Diene conjugates (DC), Schiff bases (SB), and creatine kinase (CK) were also measured in blood plasma and saliva before and immediately after HIIE in both groups.

Results

HIIE performance expressed as number of points according to a single assessment system developed and approved by the International Swimming Federation (FINA points) significantly improved in RJQ group (p = 0.013) compared to PLA group. Exercise-induced increase in DC, SB, and CK levels in plasma and saliva significantly diminished only in RJQ group (p < 0.05). Regression analysis showed that oral RJQ administration for 10 days was significantly associated with reductions in HIIE-induced increases in plasmatic and salivary DC, SB, and CK levels compared to PLA. Principal component analysis revealed that swimmers treated with RJQ are grouped by both plasmatic and salivary principal components (PC) into a separate cluster compared to PLA. Strong negative correlation between the number of FINA points and plasmatic and salivary PC1 values was observed in both intervention groups.

Conclusion

The improvements in swimmers’ HIIE performance were due in significant part to RJQ-induced reducing in lipid peroxidation and muscle damage in response to exercise. These findings suggest that RJQ supplementation for 10 days is potentially effective for enhancing HIIE performance and alleviating oxidant stress.

Abbreviations

RJ, royal jelly; CoQ10, coenzyme Q10; HIIE, high-intensity interval exercise; DC, diene conjugates; SB, Schiff bases; CK, creatine kinase; RJQ, royal jelly plus coenzyme Q10; PLA, placebo; FINA points, points according to a single assessment system developed and approved by the International Swimming Federation; ROS, reactive oxygen species; 10H2DA, 10-hydroxy-2-decenoic acid; AMPK, 5′-AMP-activated protein kinase; FoxO3, forkhead box O3; MnSOD, manganese-superoxide dismutase; CAT, catalase; E, optical densities; PCA, principal component analysis; PC, principal component; MCFAs, medium-chain fatty acids; CaMKKβ, Ca²⁺/calmodulin-dependent protein kinase β; TBARS, thiobarbituric acid reactive substances; MDA, malondialdehyde.

The effects of anabolic-androgenic steroids on DNA damage in bodybuilders' blood lymphocytes

BACKGROUND

Nowadays bodybuilders use anabolic steroids frequently. Abuse of these substances can cause significant side effects; therefore, we aim to investigate the effect of anabolic steroids on DNA damage in bodybuilders' blood lymphocytes.

METHODS AND MATERIALS

This case-control study was performed on 36 male bodybuilders in Gonabad. The case group included bodybuilders with a history of taking anabolic-androgenic steroids (n = 18), and the control group composed of bodybuilders who did not use anabolic-androgenic steroids (n = 18). Intravenous blood samples were obtained and then the lymphocytes, cells and electrophoresis of blood were extracted. Afterward, the coloured slides and DNA damage were measured using a fluorescent microscope and CometScore software. The DNA damage was compared using t-tests .

RESULTS

Results showed that there was no significant difference between age, marital status, BMI, systolic and diastolic blood pressure in the case and control group. However, parameters related to the DNA damage including tail length, percent tail DNA, and tail moment were significantly higher in the case group.

CONCLUSION

The use of anabolic-androgenic steroids increases DNA damage in the bodybuilders' blood lymphocytes.

Antioxidant supplements and endurance exercise: Current evidence and mechanistic insights

Antioxidant supplements are commonly consumed by endurance athletes to minimize exercise-induced oxidative stress, with the intention of enhancing recovery and improving performance. There are numerous commercially available nutritional supplements that are targeted to athletes and health enthusiasts that allegedly possess antioxidant properties. However, most of these compounds are poorly investigated with respect to their in vivo redox activity and efficacy in humans. Therefore, this review will firstly provide a background to endurance exercise-related redox signalling and the subsequent adaptations in skeletal muscle and vascular function. The review will then discuss commonly available compounds with purported antioxidant effects for use by athletes. N-acetyl cysteine may be of benefit over the days prior to an endurance event; while chronic intake of combined 1000 mg vitamin C + vitamin E is not recommended during periods of heavy training associated with adaptations in skeletal muscle. Melatonin, vitamin E and α-lipoic acid appear effective at decreasing markers of exercise-induced oxidative stress. However, evidence on their effects on endurance performance are either lacking or not supportive. Catechins, anthocyanins, coenzyme Q10 and vitamin C may improve vascular function, however, evidence is either limited to specific sub-populations and/or does not translate to improved performance. Finally, additional research should clarify the potential benefits of curcumin in improving muscle recovery post intensive exercise; and the potential hampering effects of astaxanthin, selenium and vitamin A on skeletal muscle adaptations to endurance training. Overall, we highlight the lack of supportive evidence for most antioxidant compounds to recommend to athletes.

Phytoplankton Supplementation Lowers Muscle Damage and Sustains Performance across Repeated Exercise Bouts in Humans and Improves Antioxidant Capacity in a Mechanistic Animal

The purpose of this study was to investigate the impact of antioxidant-rich marine phytoplankton supplementation (Oceanix, OCX) on performance and muscle damage following a cross-training event in endurance-trained subjects. Additionally, an animal model was carried out to assess the effects of varying dosages of OCX, with exercise, on intramuscular antioxidant capacity.

METHODS

In the human trial, endurance-trained subjects (average running distance = 29.5 ± 2.6 miles × week^-1) were randomly divided into placebo (PLA) and OCX (25 mg) conditions for 14 days. The subjects were pre-tested on a one-mile uphill run, maximal isometric strength, countermovement jump (CMJ) and squat jump (SJ) power, and for muscle damage (creatine kinase (CK)). On Day 12, the subjects underwent a strenuous cross-training event. Measures were reassessed on Day 13 and 14 (24 h and 48 h Post event). In the animal model, Wistar rats were divided into four groups (n = 7): (i) Control (no exercise and placebo (CON)), (ii) Exercise (E), (iii) Exercise + OCX 1 (Oceanix, 2.55 mg/day, (iv) Exercise + OCX 2 (5.1 mg/day). The rats performed treadmill exercise five days a week for 6 weeks. Intramuscular antioxidant capacity (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px)) and muscle damage (CK and myoglobin (MYOB) were collected. The data were analyzed using repeated measures ANOVA and t-test for select variables. The alpha value was set at p < 0.05.

RESULTS

For the human trial, SJ power lowered in PLA relative to OCX at 24 h Post (-15%, p < 0.05). Decrements in isometric strength from Pre to 48 h Post were greater in the PLA group (-12%, p < 0.05) than in the OCX. Serum CK levels were greater in the PLA compared to the OCX (+14%, p < 0.05). For the animal trial, the intramuscular antioxidant capacity was increased in a general dose-dependent manner (E + Oc2 > E + Oc1 > E > CON). Additionally, CK and MYOB were lower in supplemented compared to E alone.

CONCLUSIONS

Phytoplankton supplementation (Oceanix) sustains performance and lowers muscle damage across repeated exercise bouts. The ingredient appears to operate through an elevating oxidative capacity in skeletal muscle.

Exercise-Induced Oxidative Stress and the Effects of Antioxidant Intake from a Physiological Viewpoint

It is well established that the increase in reactive oxygen species (ROS) and free radicals production during exercise has both positive and negative physiological effects. Among them, the present review focuses on oxidative stress caused by acute exercise, mainly on evidence in healthy individuals. This review also summarizes findings on the determinants of exercise-induced oxidative stress and sources of free radical production. Moreover, we outline the effects of antioxidant supplementation on exercise-induced oxidative stress, which have been studied extensively. Finally, the following review briefly summarizes future tasks in the field of redox biology of exercise. In principle, this review covers findings for the whole body, and describes human trials and animal experiments separately.

Reduced graphene oxide-ZnO nanocomposite based electrochemical sensor for sensitive and selective monitoring of 8-hydroxy-2'-deoxyguanosine

Developing reliable and feasible electrochemical sensors for the detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) is important because the urinary level of 8-OHdG is related to cancer disease. Moreover, the co-existed uric acid (UA) as an interference severe affects the sensitive detection of 8-OHdG. Herein, sensitive monitoring of 8-OHdG was conducted using a nanocomposite of reduced graphene oxide (rGO) and ZnO nanoparticles (ZnO@rGO) as the sensing material. This nanocomposite was prepared via in-situ reduction of GO with Zn powders. Compared with those obtained on the unmodified glassy carbon electrode (GCE) and GO modified GCE (GO/GCE) the oxidation signals of 8-OHdG are significantly enhanced on the ZnO@rGO nanocomposite coated GCE (ZnO@rGO/GCE). Moreover, uricase has been employed successfully to eliminate the interferences of UA. A large amount of UA did not affect the oxidation signals of trace level of 8-OHdG. The linear range for the detection of 8-OHdG using ZnO@rGO/GCE was from 5.0 to 5000.0 nM. The detection limit was 1.25 nM calculated from a three-signal-to-noise ratio. The developed monitoring system is sensitive and selective for the determination of 8-OHdG and thus useful in practical applications, such as for the monitoring of 8-OHdG in the clinic urine samples.

Effects of repeated bouts of long-duration endurance exercise on muscle and urinary levels of 8-hydroxy-2'-deoxyguanosine in moderately trained cyclists

The purpose of this study was to determine the effects of repeated bouts of long-duration endurance exercise on both muscle and urinary levels of oxidative DNA damage in moderately trained individuals. Seven moderately trained male cyclists participated in this study. All participants repeated two sessions consisting of a 5-h cycling period (equivalent to approximately 52%[Formula: see text]O2peak) followed by a 15-h rest, then a 40-km time trial. During the sessions, participants were instructed to take water ad libitum and to consume a standard sports drink consisting of 0.12 g·kg(-1) body weight·hr(-1) of carbohydrates. For each session, 24 h urine output was collected on the day before the 5-h exercise, and also between the 5-h exercise and 40-km time trial, in addition to between days 1-5 post-exercise. Subsequently, muscle and urinary levels of 8-hydroxy-2'- deoxyguanosine (8-OHdG) were determined using high performance liquid chromatography with electrochemical detection. No significant alterations were observed between two sessions at the muscle or urinary levels of 8-OHdG. These results suggest that repeated bouts of exercise with a 7-day washout period may not lead to an accumulation of DNA damage products after a second 5-h stationary cycling bout.

Changes in urinary 8-hydroxydeoxyguanosine levels during heptathlon race in professional female athletes

Acute strenuous exercise can induce a state of oxidative stress affecting the involved muscles. Heptathlon is a multi-event exercise of two days duration and can be considered an acute, intensive endurance exercise. The purpose of this study is to compare the oxidative stress response to heptathlon events day by day and to determine the impact of this type of exercise on oxidative stress biomarkers.

The study subjects included eight heptathlon athletes who participated in the National First Class Republic competition in Egypt (October 19–21, 2011). Blood samples were collected at rest after exercise for two successive days and analyzed for malondialdehyde (MDA). Morning urine samples were collected one hour after exercise for each day and were analyzed for 8-hydroxydeoxyguanosine (8-OHdG). Results revealed a significant increase (p<0.05) in both plasma MDA and urine 8-OHdG levels after exercise regardless of the day. We concluded that exercise generates higher MDA levels compared to DNA strand breaks and oxidative DNA damage in athletes with antioxidant supplementation.

Long-term oral feeding of lutein-fortified milk increases voluntary running distance in rats

To evaluate the effects of lutein-fortified milk administration on running exercise, a voluntary wheel-running model was performed in rats. Four-week-old F344 rats were administered test milk (10 mL/kg) daily following a 4-h fasting period, and their running distances were measured each day for a 9-week period. Total weekly running distance significantly increased from the sixth week until the end of the test period in lutein-supplemented rats (lutein-fortified milk administered) compared with control rats (vehicle administered). This increase was not apparent in rats administered lutein alone. In the lutein-fortified-milk exercise group compared with the sedentary control group, carnitine palitroyltransferase 1 (CPT-1), total AMP-activated protein kinase (tAMPK), and phosphorylated AMP-activated protein kinase (pAMPK) contents were significantly increased in the gastrocnemius muscle, with a concomitant decrease in triglyceride and total cholesterol levels in the blood and liver. Furthermore, the lutein level in blood of lutein-administered rats significantly decreased with exercise. These results suggest that lutein-fortified milk may enhance the effect of exercise by effective utilization of lipids when combined with voluntary running.

Time-course changes of oxidative stress response to high-intensity discontinuous training versus moderate-intensity continuous training in masters runners

Beneficial systemic effects of regular physical exercise have been demonstrated to reduce risks of a number of age-related disorders. Antioxidant capacity adaptations are amongst these fundamental changes in response to exercise training. However, it has been claimed that acute physical exercise performed at high intensity (>60% of maximal oxygen uptake) may result in oxidative stress, due to reactive oxygen species being generated excessively by enhanced oxygen consumption. The aim of this study was to evaluate the effect of high-intensity discontinuous training (HIDT), characterized by repeated variations of intensity and changes of redox potential, on oxidative damage. Twenty long-distance masters runners (age 47.8 ± 7.8 yr) on the basis of the individual values of gas exchange threshold were assigned to a different 8-weeks training program: continuous moderate-intensity training (MOD, n = 10) or HIDT (n = 10). In both groups before (PRE) and after (POST) training we examined the following oxidative damage markers: thiobarbituric acid reactive substances (TBARS) as marker of lipid peroxidation; protein carbonyls (PC) as marker of protein oxidation; 8-hydroxy-2-deoxy-guanosine (8-OH-dG) as a biomarker of DNA base modifications; and total antioxidant capacity (TAC) as indicator of the overall antioxidant system. Training induced a significant (p<0.05) decrease in resting plasma TBARS concentration in both MOD (7.53 ± 0.30 and 6.46 ± 0.27 µM, PRE and POST respectively) and HIDT (7.21 ± 0.32 and 5.85 ± 0.46 µM, PRE and POST respectively). Resting urinary 8-OH-dG levels were significantly decreased in both MOD (5.50 ± 0.66 and 4.16 ± 0.40 ng mg(-1)creatinine, PRE and POST respectively) and HIDT (4.52 ± 0.50 and 3.18 ± 0.34 ng mg(-1)creatinine, PRE and POST respectively). Training both in MOD and HIDT did not significantly modify plasma levels of PC. Resting plasma TAC was reduced in MOD while no significant changes were observed in HIDT. In conclusion, these results suggest that in masters runners high-intensity discontinuous does not cause higher level of exercise-induced oxidative stress than continuous moderate-intensity training, inducing similar beneficial effects on redox homeostasis.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Antioxidant supplementation during exercise training: beneficial or detrimental?

High levels of reactive oxygen species (ROS) produced in skeletal muscle during exercise have been associated with muscle damage and impaired muscle function. Supporting endogenous defence systems with additional oral doses of antioxidants has received much attention as a noninvasive strategy to prevent or reduce oxidative stress, decrease muscle damage and improve exercise performance. Over 150 articles have been published on this topic, with almost all of these being small-scale, low-quality studies. The consistent finding is that antioxidant supplementation attenuates exercise-induced oxidative stress. However, any physiological implications of this have yet to be consistently demonstrated, with most studies reporting no effects on exercise-induced muscle damage and performance. Moreover, a growing body of evidence indicates detrimental effects of antioxidant supplementation on the health and performance benefits of exercise training. Indeed, although ROS are associated with harmful biological events, they are also essential to the development and optimal function of every cell. The aim of this review is to present and discuss 23 studies that have shown that antioxidant supplementation interferes with exercise training-induced adaptations. The main findings of these studies are that, in certain situations, loading the cell with high doses of antioxidants leads to a blunting of the positive effects of exercise training and interferes with important ROS-mediated physiological processes, such as vasodilation and insulin signalling. More research is needed to produce evidence-based guidelines regarding the use of antioxidant supplementation during exercise training. We recommend that an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status in exercising individuals.

Exercise-induced lipid peroxidation: Implications for deoxyribonucleic acid damage and systemic free radical generation

Exercise-induced deoxyribonucleic acid (DNA) damage is often associated with an increase in free radicals; however, there is a lack of evidence examining the two in parallel. This study tested the hypothesis that high-intensity exercise has the ability to produce free radicals that may be capable of causing DNA damage. Twelve apparently healthy male subjects (age: 23 ± 4 years; stature: 181 ± 8 cm; body mass: 80 ± 9 kg; and VO(2max) : 49 ± 5 ml/kg/min) performed three 5 min consecutive and incremental stages (40, 70, and 100% of VO(2max) ) of aerobic exercise with a 15-min period separating each stage. Blood was drawn after each bout of exercise for the determination of ex vivo free radicals, DNA damage, protein carbonyls, lipid hydroperoxide (LOOH) concentration, and a range of lipid-soluble antioxidants. Lipid-derived oxygen-centered free radicals (hyperfine coupling constants a(Nitrogen) = 13.7 Gauss (G) and aβ(Hydrogen) = 1.8 G) increased as a result of acute moderate and high-intensity exercise (P < 0.05), while DNA damage was also increased (P < 0.05). Systemic changes were observed in LOOH and for lipid-soluble antioxidants throughout exercise (P < 0.05); however, there was no observed change in protein carbonyl concentration (P > 0.05). These findings identify lipid-derived free radical species as possible contributors to peripheral mononuclear cell DNA damage in the human exercising model. This damage occurs in the presence of lipid oxidation but in the absence of any change to protein carbonyl concentration. The significance of these findings may have relevance in terms of immune function, the aging process, and the pathology of carcinogenesis.

Role of dietary antioxidants in the prevention of in vivo oxidative DNA damage

Epidemiological evidence consistently shows that diets high in fresh fruit and vegetables significantly lower cancer risk. Given the postulated role of oxidative DNA damage in carcinogenesis, the assumption has been made that it is the antioxidant properties of food constituents, such as vitamin C, E and carotenoids, which confer protection. However, epidemiological studies with specific antioxidants, either singly or in combination, have not, on the whole, supported this hypothesis. In contrast, studies examining the in vitro effect of antioxidants upon oxidative DNA damage have generally been supportive, in terms of preventing damage induction. The same, however, cannot be said for the in vivo intervention studies where overall the results have been equivocal. Nevertheless, recent work has suggested that some dietary antioxidants may confer protective properties through a novel mechanism, unrelated to their conventional free-radical scavenging abilities. Upregulation of antioxidant defence, xenobiotic metabolism, or DNA-repair genes may all limit cellular damage and hence promote maintenance of cell integrity. However, until further work has clarified whether dietary supplementation with antioxidants confers a reduced risk of cancer and the mechanism by which this effect is exerted, the recommendation for a diet rich in fruit and vegetables remains valid empirically.

Variegate porphyria induces plasma and neutrophil oxidative stress: effects of dietary supplementation with vitamins E and C

Our aim was to analyse the influence of variegate porphyria (VP) on the antioxidant defenses and markers of oxidative damage and inflammation in plasma and neutrophils and the effects of dietary supplementation with vitamins E and C on these parameters in plasma, neutrophils and erythrocytes. Twelve women affected by VP and twelve pair-matched healthy control women participated in a double-blind crossover study. Each participant took 50 mg/d of vitamin E and 150 mg/d of vitamin C, or a placebo, for 6 months, by consuming an almond-based beverage as the vehicle. Women affected by VP presented higher C-reactive protein and malondialdehyde (MDA) circulating levels. Plasma antioxidant defenses were not different between porphyric and control women. Neutrophils from VP women presented decreased catalase (CAT) and glutathione reductase (GR) activities together with increased protein carbonyl levels. Reactive oxygen species (ROS) production from stimulated neutrophils was also higher in porphyric women than their controls. Dietary supplementation was effective in increasing α-tocopherol levels in neutrophils and in reducing MDA levels in plasma. Erythrocyte CAT and GR activities were enhanced by the enriched beverage only in the control subjects. In conclusion, women affected by VP present a situation of inflammation, plasma oxidative damage and neutrophils more primed to the oxidative burst, with decreased antioxidant activities and increased ROS production capabilities and protein oxidative damage. Dietary supplementation with vitamin E (50 mg/d) and vitamin C (150 mg/d) for 6 months decreased plasma oxidative damage and enhanced the erythrocyte activities of CAT and GR.

Endurance exercise and DNA stability: is there a link to duration and intensity?

It is commonly accepted that regular moderate intensity physical activity reduces the risk of developing many diseases. Counter intuitively, however, evidence also exists for oxidative stress resulting from acute and strenuous exercise. Enhanced formation of reactive oxygen and nitrogen species may lead to oxidatively modified lipids, proteins and nucleic acids and possibly disease. Currently, only a few studies have investigated the influence of exercise on DNA stability and damage with conflicting results, small study groups and the use of different sample matrices or methods and result units. This is the first review to address the effect of exercise of various intensities and durations on DNA stability, focusing on human population studies. Furthermore, this article describes the principles and limitations of commonly used methods for the assessment of oxidatively modified DNA and DNA stability. This review is structured according to the type of exercise conducted (field or laboratory based) and the intensity performed (i.e. competitive ultra/endurance exercise or maximal tests until exhaustion). The findings presented here suggest that competitive ultra-endurance exercise (>4h) does not induce persistent DNA damage. However, when considering the effects of endurance exercise (<4h), no clear conclusions could be drawn. Laboratory studies have shown equivocal results (increased or no oxidative stress) after endurance or exhaustive exercise. To clarify which components of exercise participation (i.e. duration, intensity and training status of subjects) have an impact on DNA stability and damage, additional carefully designed studies combining the measurement of DNA damage, gene expression and DNA repair mechanisms before, during and after exercise of differing intensities and durations are required.

Does physical exercise modify antioxidant requirements?

Physical training is known to induce a biochemical adaptive response which might require an increase in the ingestion and/or the absorption of micronutrients. A question that is still being raised is whether acute or chronic exercise modifies antioxidant requirements. First, the present review brings to light the most crucial studies on the topic. Second, it interprets the established relationships between antioxidant micronutrient intakes and the adaptive response of antioxidant systems. Finally, it exposes the major questions connected with antioxidant micronutrient requirements for athletes. To this effect, the training-load interaction with nutrition is taken into account. As oxidative stress cannot be avoided, the imbalance between oxidants and antioxidants can be alleviated to minimise oxidative damage and outcomes. There is growing evidence that one specific antioxidant cannot by itself prevent oxidative stress-induced damage, as direct adverse effects of supplementation are attributed to undesirable synergic effects. Other effects can be supposed that limit the endogenous adaptive effect of training. High doses of antioxidant supplements can minimise the effects of radical oxygen species themselves or generate pro-oxidant effects. Effects are only exhibited when nutritional status is deficient. There are no convincing effects of supplementation in well-trained athletes. Risk/benefit analysis emerges on evidence for an unknown risk of supranutritional intakes, a supposed impairment of adaptive effects and a still unknown long-term risk. Appropriate status can be achieved by a diversified and balanced diet, adapted to specific needs, by awareness of high-density food intakes (avoiding products containing a low density of micronutrients).

Acute exercise and oxidative stress: a 30 year history

The topic of exercise-induced oxidative stress has received considerable attention in recent years, with close to 300 original investigations published since the early work of Dillard and colleagues in 1978. Single bouts of aerobic and anaerobic exercise can induce an acute state of oxidative stress. This is indicated by an increased presence of oxidized molecules in a variety of tissues. Exercise mode, intensity, and duration, as well as the subject population tested, all can impact the extent of oxidation. Moreover, the use of antioxidant supplements can impact the findings. Although a single bout of exercise often leads to an acute oxidative stress, in accordance with the principle of hormesis, such an increase appears necessary to allow for an up-regulation in endogenous antioxidant defenses. This review presents a comprehensive summary of original investigations focused on exercise-induced oxidative stress. This should provide the reader with a well-documented account of the research done within this area of science over the past 30 years.

Effect of exercise on oxidative stress biomarkers

Acute bouts of aerobic and anaerobic exercise can induce a state of oxidative stress, as indicated by an increase in oxidized molecules in a variety of tissues and body fluids. The extent of oxidation is dependent on the exercise mode, intensity, and duration, and is specifically related to the degree of oxidant production. Findings of increased oxidative stress have been reported for both healthy and diseased subjects following single bouts of exercise. While acute exercise has the ability to induce an oxidative stress, this same exercise stimulus appears necessary to allow for an upregulation in endogenous antioxidant defenses. This chapter presents a summary of exercise-induced oxidative stress.

Short-term moderate exercise programs reduce oxidative DNA damage as determined by high-performance liquid chromatography-electrospray ionization-mass spectrometry in patients with colorectal carcinoma following primary treatment

OBJECTIVE

Oxidative DNA damage is believed to be involved in tumor formation and may be an important biomarker for malignant transition or relapse. A decrease of such damage has been observed in human and animal studies following dietary intervention and/or changes in lifestyle such as physical exercise at different levels of intensity. The purpose of this study was to carry out a clinical trial comparing the effects of a short-term (2 weeks) exercise program of moderate intensity (0.3-0.4 x maximal exercise capacity) (MI) versus high intensity (0.5-0.6 x maximal exercise capacity) (HI) on individual urinary excretion of 8-oxo-dG before and after completion of the exercise programs.

MATERIAL AND METHODS

In this short-term, prospective and randomized trial, 19 patients with colorectal cancer were allocated to the MI group following primary therapy and 29 to the HI group. Urinary 8-oxo-dG excretion concentration was determined by a highly sensitive detection method using high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS). Concentrations were determined immediately before and after completion of the exercise programs.

RESULTS

Using HPLC-ESI-MS, it was shown that MI exercise significantly reduced urinary 8-oxo-dG excretion levels from 8.47 +/- 1.99 to 5.81 +/- 1.45 (ng/mg creatinine, mean +/- SE, p = 0.02), whereas HI exercise resulted in a non-significant increase from 5.00 +/- 1.31 to 7.11 +/- 1.63 (ng/mg creatinine, p = 0.18). Clinical characteristics (gender, age, body mass index (BMI), diet, chemotherapy/irradiation) were not associated/correlated with urinary 8-oxo-dG levels.

CONCLUSIONS

By using HPLC-ESI-MS it was shown that short-term MI exercise after primary therapy in patients with colorectal cancer was associated with lower levels of urinary 8-oxo-dG, suggesting decreased oxidative DNA damage. In contrast, HI exercise tended to increase DNA damage. A prospective trial is now warranted to prove that reduced oxidative DNA damage lowers the risk of relapse of colorectal cancer in treated patients.

Antioxidant vitamins and cancer risk: is oxidative damage to DNA a relevant biomarker?

Oxidative damage to DNA is regarded as an important step in carcinogenesis. These lesions may arise as a consequence of exposure to xenobiotics, but are also generated as a consequence of endogenous generation of oxidizing compounds. Measurements of oxidative damage to guanines, such as 8-oxo-7, 8-dihydroguanine (8-oxodG) are increasingly being regarded as reliable biomarkers of oxidative stress and they may have a predictive value of cancer risk, although this needs to be established independently in several cohort studies. A survey of intervention studies of the ingestion of antioxidant-containing foods or tablets of antioxidants indicate that about one-third of the studies reported a protective effect in terms of lower levels of oxidative damage to DNA in white blood cells or decreased urinary excretion of 8-oxodG. Although firm conclusions cannot be reached, there appears to be links between ingestion of antioxidants, oxidative damage to DNA, and risk of cancer.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival.

OBJECTIVES

To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials.

SEARCH STRATEGY

We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials).

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.

DNA damage, a biomarker of carcinogenesis: its measurement and modulation by diet and environment

Free radicals and other reactive oxygen or nitrogen species are constantly generated in vivo and can cause oxidative damage to DNA. This damage has been implicated to be important in many diseases, including cancer. The assessment of damage in various biological matrices, such as tissues, cells, and urine, is vital to understanding this role and subsequently devising intervention strategies. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay. The objective of this review is to discuss the biological significance of oxidative DNA damage, evaluate the effectiveness of several techniques for measurement of oxidative DNA damage in various biological samples and review current research on factors (dietary and non-dietary) that influence DNA oxidative damage using these techniques.

Dietary antioxidants for the athlete

Physical exercise induces oxidative stress and tissue damage. Although a basal level of reactive oxygen species (ROS) is required to drive redox signaling and numerous physiologic processes, excess ROS during exercise may have adverse implications on health and performance. Antioxidant nutrients may be helpful in that regard. Caution should be exercised against excess antioxidant supplements, however. This article presents a digest for sports practitioners. The following three recommendations are made: 1) it is important to determine the individual antioxidant need of each athlete performing a specific sport; 2) multinutrient preparations, as opposed to megadoses of any single form of nutrient, seem to be a more prudent path to choose; and 3) for outcomes of antioxidant supplementation, performance should not be the only criteria. Overall well being of the athlete, faster recovery, and minimization of injury time could all be affected by antioxidant therapy.

Exercise and functional foods

Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning, recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. In addition, several natural food components have been found to show physiological effects, and some of them are considered to be useful for promoting exercise performance or for prevention of injury. However, these foods should only be used when there is clear scientific evidence and with understanding of the physiological changes caused by exercise. This article describes various "functional foods" that have been reported to be effective for improving exercise performance or health promotion, along with the relevant physiological changes that occur during exercise.

Oxidative stress response in normal and antioxidant supplemented rats to a downhill run: changes in blood and skeletal muscles

The purpose of this study was to determine if changes in oxidative stress biomarkers in blood and skeletal muscles are similar in normal and antioxidant supplemented rats after a downhill run. Sixty-six male Sprague-Dawley rats were pretreated with a normal rat diet or diet + antioxidants (2,000 mg vitamin C + 1,000 IU vitamin E/kg diet) for 2 weeks. Exercised rats ran 90 min on a rodent treadmill at a speed of 16 m/min at -16 degrees grade. Rats were sacrificed either at rest, immediately, 2 hrs, or 48 hrs postexercise. Malondialdehyde (MDA) and protein carbonyl (PC) concentrations and glutathione status in blood, vastus lateralis (white fast-twitch), vastus intermedius (red fast-twitch), and soleus (slow-twitch) muscles were determined. A significant increase from rest in PC occurred in plasma, vastus intermedius and soleus muscle 2 hrs after the downhill run (p < 0.05), with no changes observed at any other times postexercise. Antioxidant supplementation significantly decreased PC concentrations in both vastus intermedius and soleus muscles at all times combined (p < 0.05). MDA and glutathione status in blood and muscles were unaffected by either the downhill run or antioxidant treatment. For PC and MDA, the concentrations were lower in blood as compared to skeletal muscle, with the opposite finding for oxidized glutathione; however, the pattern of response postexercise was similar. These data indicate that (a) PC, but not MDA or oxidized glutathione, is elevated transiently following downhill running in male rats; (b) the elevation in PC postexercise occurs in plasma, vastus intermedius, and soleus muscles; (c) antioxidant therapy can attenuate PC in vastus intermedius, and soleus muscles; and (d) while the concentrations of oxidative stress biomarkers differ between blood and the various skeletal muscles, the pattern of response postexercise is similar.

The effects of an antioxidant-supplemented beverage on exercise-induced oxidative stress: results from a placebo-controlled double-blind study in cyclists

The objective of this study was to test the effects of an antioxidant-supplemented beverage on exercise-induced oxidative stress in moderately trained cyclists. A double-blind study was conducted in moderately trained cyclists. They were randomly allocated to receive either an antioxidant (13 subjects) or a placebo (13 subjects) 15 min pre-exercise (30 ml.kg(-1)) and during a 90 min constant-load test (30 ml.kg(-1).15 min(-1)) on a bicycle ergometer at 70% VO2max The supplemented beverage contained black grape (81 g/l), raspberry (93 g/l) and red currant (39 g/l) concentrates, and its total antioxidant capacity, measured by the ABTS(.+) technique, was 0.41 mM Trolox. No significant difference from basal to post-exercise period was detected for plasma TBARS in either the placebo group or the group receiving the antioxidant supplemented beverage. Post-exercise carbonyls decreased by 29% in the group receiving antioxidants, and the pattern of change was significantly different between antioxidant and placebo conditions. The urinary excretion of 8-OHdG increased significantly by 21% in the placebo group. Again differences in the pre- to post-exercise change were significant between both conditions These results suggest that in moderately trained cyclists, antioxidant supplementation counters oxidative stress induced by a 90 min exercise at 70% VO2max.

Effect of aerobic exercise training on mtDNA deletion in soleus muscle of trained and untrained Wistar rats

BACKGROUND

According to the theory of mitochondrial aging, oxidative stress plays a major role in aging and age related degenerative diseases. Since oxygen consumption and reactive oxygen species rate increase during aerobic exercise, we hypothesised that heavy aerobic training could lead to enhanced mitochondrial DNA (mtDNA) deletion in postmitotic tissues, leading in turn to premature aging and degenerative diseases.

METHODS

Sixty adult male 2 month old Wistar14848 rats were divided into six equal groups. Two groups were trained for 3 months by running on a treadmill (5 days/week, incline 6 degrees; group 1: 40 m/min, 20 min/day; group 2: 20 m/min, 40 min/day), while two sedentary groups participated in aerobic exercise only at the end of the study (incline 6 degrees; group 3: 40 m/min; group 4: 20 m/min). To control for physical and physiological parameters, two groups of untrained animals were killed at the beginning (group 6) and end (group 5) of the study. Expand long PCR was used to investigate mtDNA deletion in soleus muscle and a sequencing method was used to confirm the mtDNA deletion break point.

RESULTS

Our results did not show any mtDNA deletion in untrained rats or in those that underwent moderate training (group 2) We only found mtDNA deletion (4.6 kb) in the soleus muscle of heavily trained rats (group 1).

CONCLUSIONS

These results demonstrate that one session of aerobic exercise does not cause mtDNA deletion in skeletal muscle. The difference in results between heavy and moderate aerobic training may be due to low work rate or up-regulation of inducible antioxidant systems in moderate training.

Extreme Running Competition Decreases Blood Antioxidant Defense Capacity

OBJECTIVE

We tested whether an extreme running competition ("Marathon of Sands") might alter the blood's enzymatic and non-enzymatic antioxidant status in 6 well-trained athletes.

METHODS

The Marathon of Sands is a competition consisting of six long duration races in the desert in which the athletes carry their own food. Blood samples were collected from an antecubital vein while the athletes were at rest before the competition and then again 72 hours after. Erythrocyte antioxidant enzyme activity (glutathione peroxidase, superoxide dismutase), erythrocyte glutathione level, plasma non-enzymatic status (vitamin C, alpha-tocopherol, retinol, beta-carotene and carotenoids) and plasma lipid peroxidation marker (TBARS) were measured.

RESULTS

The Marathon of Sands induced a significant alteration of the blood antioxidant defense capacity. Indeed, 72 hours after the race, significant decreases were recorded in erythrocyte superoxide dismutase activity and in plasma concentrations of retinol, beta-carotene and other carotenoids. These changes were associated with a concomitant increase in erythrocyte glutathione and in plasma TBARS levels.

CONCLUSION

This study indicated that such extreme competition induced an imbalance between oxidant and antioxidant protection.

Marathon Running Leads to Partial Exhaustion of ROS-Generating Capacity in Leukocytes

PURPOSE

The aim of the present study was to investigate the changes occurring in leukocyte levels of reactive oxygen species (ROS) and total blood plasma antioxidant capacity (TAS) as a result of a marathon/half-marathon race.

METHODS

Fourteen men participating in the Oslo Marathon 2000 and 8 women and 8 men participating in the Oslo Half-Marathon 2001 were recruited to the study. Flow cytometry and the ROS-sensitive probe dihydroethidium (DHE) were used to study the intracellular levels of ROS in circulating leukocytes. Both basal ROS levels as well as the capacity of leukocytes to respond with ROS synthesis upon a defined in vitro stimulus, i.e., phorbol myristate acetate (PMA) was assessed before and immediately after the races. TAS was measured using the ABTS+ reduction assay kit.

RESULTS

The basal levels of ROS in leukocytes were either not significantly changed (men, 3-25% reduced) or reduced 33% (women, P < 0.01) as a result of the marathon/half-marathon race. After the marathon race, the capacity of leukocytes to produce ROS upon PMA stimulation was reduced, i.e., 6% (granulocytes) (P < 0.001) and 23% (monocytes) (P < 0.01) residual capacity compared with the prerace situation. A 22-30% reduction (P < 0.05) in monocyte ROS response was seen also as a result of the half-marathon race, whereas the granulocyte ROS response was maintained at the prerace level (19% (women) and 15% (men) reduction, NS)). TAS increased significantly (11-19%, P < 0.05) after both races.

CONCLUSIONS

The present results indicate an exhaustion of leukocyte ROS-generating mechanisms after prolonged strenuous exercise. This may partly explain the observation that athletes are more sensitive to attract infectious diseases if exposed to pathogenic micro-organisms during the immediate period after intensive physical activity.

Physical fitness and plasma non-enzymatic antioxidant status at rest and after a wingate test

We tested seven physical education students whether 30-s sprint anaerobic exercise (Wingate test) would result in oxidative stress (evaluated by lipid radical levels) sufficient to alter plasma non-enzymatic antioxidant status (plasma uric acid, ascorbic acid, alpha-tocopherol, beta-carotene). This study demonstrates that 1) Wingate test increases plasma uric and ascorbic acid concentrations (p <.05), and decreases plasma alpha-tocopherol and beta-carotene levels (p <.05); 2) lipid radical levels at rest and sprint performance are negatively correlated with resting plasma uric acid and alpha-tocopherol concentrations (p <.05). In conclusion, this study 1) demonstrates that a 30-s sprint anaerobic exercise is associated with acute changes in plasma non-enzymatic antioxidant status, 2) indicates that the subjects with largest leg peak power are those who exhibit the lowest plasma antioxidant status at rest (uric acid and alpha-tocopherol), 3) and suggests that antioxidant intake by maintaining plasma antioxidant concentration at rest in the normal range might protect athletes against oxidative stress induced by exercise.

Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a marker of oxidative stress in rheumatoid arthritis and aging: effect of progressive resistance training

Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), as a measure of oxidative stress, was measured before and after 12 weeks of progressive resistance strength training in 8 healthy elderly (65-80 yr) and eight healthy young (22-30 yr) men and women, and in eight adults (25-65 yr) with rheumatoid arthritis (RA).Training subjects exercised at 80% of their one-repetition maximum and performed eight repetitions per set, three sets per session, on a twice-weekly basis. 8-OHdG was measured at baseline and follow-up (at least 24 hr after the last exercise session) in the RA and elderly subject groups, and at baseline only in young subjects.Baseline 8-OHdG levels were greater among subjects with RA compared to both healthy young (P < 0.001) and elderly (P < 0.05) subjects. There were no changes in 8-OHdG levels in either RA or elderly subjects as a result of the strength training intervention.These results suggest that subjects with RA have higher levels of oxidative stress than young and elderly healthy individuals. Furthermore, there is no change in oxidative stress, measured by urinary 8-OHdG, in elderly healthy individuals or in subjects with RA after a 12-week strength training intervention.

Chronically and acutely exercised rats: biomarkers of oxidative stress and endogenous antioxidants

The responses to oxidative stress induced by chronic exercise (8-wk treadmill running) or acute exercise (treadmill running to exhaustion) were investigated in the brain, liver, heart, kidney, and muscles of rats. Various biomarkers of oxidative stress were measured, namely, lipid peroxidation [malondialdehyde (MDA)], protein oxidation (protein carbonyl levels and glutamine synthetase activity), oxidative DNA damage (8-hydroxy-2'-deoxyguanosine), and endogenous antioxidants (ascorbic acid, alpha-tocopherol, glutathione, ubiquinone, ubiquinol, and cysteine). The predominant changes are in MDA, ascorbic acid, glutathione, cysteine, and cystine. The mitochondrial fraction of brain and liver showed oxidative changes as assayed by MDA similar to those of the tissue homogenate. Our results show that the responses of the brain to oxidative stress by acute or chronic exercise are quite different from those in the liver, heart, fast muscle, and slow muscle; oxidative stress by acute or chronic exercise elicits different responses depending on the organ tissue type and its endogenous antioxidant levels.

Influence of one bout of vigorous exercise on ascorbic acid in plasma and oxidative damage to DNA in blood cells and muscle in untrained rats

We investigated the influence of a single exhaustive bout of downhill running on oxidative damage to DNA and changes of antioxidant vitamin concentrations in rats. Plasma vitamin E levels were unchanged up to 48 hr postexercise. However, plasma ascorbic acid (AA) levels increased after the exercise, then decreased thereafter. This increase corresponded to a marked decrease in AA concentration in the adrenal glands. The activity of hepatic l-gulono-gamma-lactone oxidase, which catalyzes AA synthesis, was unaltered after the exercise. The weight of the adrenal glands was significantly increased 24 hr postexercise. These results indicate that the change in the plasma AA concentration after vigorous exercise was due mainly to the release of AA from the adrenal glands. The plasma creatine phosphokinase (CPK) activity and white blood cell (WBC) count increased 3 to 6 hr postexercise. Over this same period, a marker of oxidative DNA damage, 8-hydroxydeoxyguanosine in DNA, increased in the WBC, but not in the foreleg muscle. Lipid peroxide and vitamin E levels were also unchanged in the foreleg muscle. There was a positive correlation between CPK activity in the plasma and DNA damage in the WBC, suggesting that the DNA damage in the WBC was closely related with muscle damage due to exercise.

Detection of a urinary biomaker for oxidative DNA damage 8-hydroxydeoxyguanosine by capillary electrophoresis with electrochemical detection

8-Hydroxydeoxyguanosine (8-OHdG) is present in urine as a result of oxidative DNA damage associated with age-related diseases such as cancer. In this report a method is presented for the detection of 8-OHdG in human morning urine utilizing capillary electrophoresis with electrochemical detection (CEEC). The limit of detection for a aqueous standard of 8-OHdG is 50 nM (signal to noise ratio S/N = 3). A single solid-phase extraction (SPE) step with a C18 column is used for sample cleanup and 20-fold preconcentration of the urine before analysis by CEEC. Optimized conditions for analysis of extracted urine are E(app) = 0.5 V vs. Ag/AgCl with 20 mM sodium borate/20% MeOH v/v, pH 9, as the background electrolyte, and a separation voltage of 22 kV. The concentration of 8-OHdG varied from 6 to 86 nM with an average value of 42 +/- 26.9 nM for four healthy female and four healthy male subjects between the ages of 23 and 43.

Methods to detect DNA damage by free radicals: relation to exercise

Epidemiological investigations repeatedly show decreased morbidity from regular exercise compared with sedentary life. A large number of investigations have demonstrated increased oxidation of important cellular macromolecules, whereas other investigators have found no effects or even signs of lowering of oxidation of macromolecules. In particular, extreme and long-duration strenuous exercise appears to lead to deleterious oxidation of cellular macromolecules. The oxidation of DNA is important because the oxidative modifications of DNA bases, particularly the 8-hydroxylation of guanine, are mutagenic and have been implicated in a variety of diseases such as ageing and cancer. The methodologies for further investigation of the relationship between DNA oxidation and exercise are available. The preferred methods rely on HPLC or GC-mass spectrometry; whereas the theoretically-attractive liquid chromatography-tandem mass spectrometry is being developed. Caution should be taken to avoid artifacts because of the six orders of magnitude of difference between oxidized and non-oxidized DNA bases in tissues. The methods can be used to estimate tissue levels, i.e. a local concentration of oxidized DNA, or to estimate the rate of body DNA oxidation by the urinary output of repair products, the latter being a method that is independent of repair. During exercise there appears to be a shifting of dietary-dependent antioxidant, e.g. vitamin C and vitamin E, from muscle to plasma, and an increased oxidation in plasma of these antioxidants. Supplementation trials with antioxidants have not been able to increase exercise performance; however, optimum nutrition with antioxidants and possibly supplementation, could be important in the prevention of diseases in the long term. The pattern from these observations appears to be quite consistent; immediately after exercise, regardless of how intense, there do not appear to be any signs of oxidative damage to DNA. Acute or prolonged moderate exercise does not produce signs of oxidative DNA damage and might even be associated with lowering of the levels of oxidation of tissue DNA; however, after long-duration and intense exercise an increase in oxidative DNA modifications is apparent. We suggest as a hypothesis that the relationship between exercise and health is U-shaped. This hypothesis needs to be tested in detail in order to establish the maximum beneficial exercise level with regard to oxidative DNA modification, and also the level that could be deleterious and might even increase the risk for cancer and other diseases.

Dietary carotenoids and lung cancer: a review of recent research

Several hundred carotenoid research studies have been published since 1996, when two major intervention trials showed a lack of protective effect of beta-carotene supplements against lung cancer. Recent epidemiologic studies continue to show an association between high dietary intake of beta-carotene and lower risk of lung cancer. New research is attempting to clarify the apparently contradictory results of intervention and epidemiologic studies. Promising areas of investigation include characterizing biologic activities of carotenoids and gaining further insight into whether they may serve primarily as markers for a healthy lifestyle or diet.