Oxidative Stress Response to Aerobic Exercise

PURPOSE

To compare the effects of two antioxidant formulas on biomarkers of oxidative stress before and after aerobic exercise.

METHODS

Aerobically trained men (N=25) and women (N=23) were assigned to one of three treatments: 400 IU of vitamin E+1 g of vitamin C (V; N=15), a fruit and vegetable juice powder concentrate (FV; N=16), or a placebo (P; N=17). Subjects ran for 30 min at 80% VO(2 max) before, after 2 wk of supplementation, and after a 1-wk washout period. Blood samples were taken before and immediately after exercise and analyzed for protein carbonyls (PC), malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), and vitamins C and E.

RESULTS

The V treatment increased plasma vitamin C and E after 2 wk (P <or= 0.05), with no change in the FV or P. Postexercise PC values were elevated for all treatments after all exercise bouts (P< 0.0001). Both V and FV attenuated the exercise-induced increase in PC after 2 wk of supplementation (V=21%, FV=17%), and after the 1-wk washout (V=13%, FV=6%) compared with P (P<0.05), with no differences between V and FV. MDA was unaffected by exercise and treatment. A treatment main effect for 8-OHdG was noted, with values for V lower than for FV and P (4.5+/-2.5, 5.5+/-2.7, and 6.0+/-2.5 ng.mL, respectively; P=0.0002). No exercise session or time main effect was noted for 8-OHdG, suggesting that the lower mean value for the V treatment group was not a result of the supplementation.

CONCLUSION

These data suggest that V and FV supplementation for 2 wk can attenuate the rise in PC after 30 min of aerobic exercise, even after a 1-wk washout, without an impact on plasma MDA or 8-OHdG.

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.

Effects of acute aerobic and anaerobic exercise on blood markers of oxidative stress

The purpose of this study was to compare oxidative modification of blood proteins, lipids, DNA, and glutathione in the 24 hours following aerobic and anaerobic exercise using similar muscle groups. Ten cross-trained men (24.3 +/- 3.8 years, [mean +/- SEM]) performed in random order 30 minutes of continuous cycling at 70% of Vo(2)max and intermittent dumbbell squatting at 70% of 1 repetition maximum (1RM), separated by 1-2 weeks, in a crossover design. Blood samples taken before, and immediately, 1, 6, and 24 hours postexercise were analyzed for plasma protein carbonyls (PC), plasma malondialdehyde (MDA), and whole-blood total (TGSH), oxidized (GSSG), and reduced (GSH) glutathione. Blood samples taken before and 24 hours postexercise were analyzed for serum 8-hydroxy-2'-deoxyguanosine (8-OHdG). PC values were greater at 6 and 24 hours postexercise compared with pre-exercise for squatting, with greater PC values at 24 hours postexercise for squatting compared with cycling (0.634 +/- 0.053 vs. 0.359 +/- 0.018 nM.mg protein(-1)). There was no significant interaction or main effects for MDA or 8-OHdG. GSSG experienced a short-lived increase and GSH a transient decrease immediately following both exercise modes. These data suggest that 30 minutes of aerobic and anaerobic exercise performed by young, cross-trained men (a) can increase certain biomarkers of oxidative stress in blood, (b) differentially affect oxidative stress biomarkers, and (c) result in a different magnitude of oxidation based on the macromolecule studied. Practical applications: While protein and glutathione oxidation was increased following acute exercise as performed in this study, future research may investigate methods of reducing macromolecule oxidation, possibly through the use of antioxidant therapy.

Effect of microhydrin on blood lactate, protein carbonyls, and glutathione status in rats before and after aerobic exercise

To examine the effects of an antioxidant treatment on blood lactate, protein carbonyls (PC), and glutathione status, 42 male rats were assigned to either a control treatment (water, C) or one of two Microhydrin treatments (added to water, MH I or MH II). Rats from each treatment were assigned to either exercise (60 min of running) or rest. A treatment-by-time interaction was noted for blood lactate, with elevations only in the C and MH I treatments post-exercise (approximately 2.54 and 2.5 mM, respectively). Both treatment and time main effects were noted for PC. Exercise resulted in an increase in PC for both Microhydrin treatments with significantly greater PC compared to C. Total blood glutathione was unaffected by treatment or exercise. Exercise increased the ratio of oxidized to total glutathione and the MH II treatment resulted in a greater ratio compared to the other treatments. In conclusion, MH II results in lower blood lactate, while resulting in an increase in the concentration of oxidized protein and glutathione, suggesting heightened oxidative stress.

Combined Antioxidant Treatment Effects on Blood Oxidative Stress after Eccentric Exercise

PURPOSE

This study was designed to ascertain the effects of a combination antioxidant therapy on plasma protein carbonyls (PC), malondialdehyde (MDA), and whole blood total (TGSH), oxidized (GSSG), and reduced (GSH) glutathione in non-resistance trained females after eccentric resistance exercise.

METHODS

Eighteen women (aged 19-31 yr) were randomized in a double-blind manner to either an antioxidant supplement (N = 9; 400 IU vitamin E, 1 g vitamin C, and 90 mug selenium per day) or a lactose placebo (N = 9) for 14 d before and for 2 d after eccentric elbow flexor exercise. Blood samples taken before and immediately, 2, 6, 24, and 48 h postexercise were analyzed for PC, MDA, TGSH, and GSSG.

RESULTS

No treatment by time interaction was noted for any variable, with all blood markers experiencing a change after the exercise in both conditions. Time main effects were observed for PC, MDA, and GSSG, with values elevated above preexercise after the eccentric exercise, whereas GSH concentration decreased after the eccentric exercise. Antioxidant supplementation resulted in a condition main effect for PC and MDA, with lower values compared with placebo. The antioxidant treatment attenuated the rise in both PC (75%) and MDA (100%).

CONCLUSION

These data suggest that eccentric resistance exercise can increase blood biomarkers of oxidative stress in non-resistance trained females, and this vitamin E, C, and selenium supplementation can attenuate the rise in PC and MDA.

Mechanical ventilation depresses protein synthesis in the rat diaphragm

Prolonged mechanical ventilation results in diaphragmatic atrophy and contractile dysfunction in animals. We hypothesized that mechanical ventilation-induced diaphragmatic atrophy is associated with decreased synthesis of both mixed muscle protein and myosin heavy chain protein in the diaphragm. To test this postulate, adult rats were mechanically ventilated for 6, 12, or 18 hours and diaphragmatic protein synthesis was measured in vivo. Six hours of mechanical ventilation resulted in a 30% decrease (p < 0.05) in the rate of mixed muscle protein synthesis and a 65% decrease (p < 0.05) in the rate of myosin heavy chain protein synthesis; this depression in diaphragmatic protein synthesis persisted throughout 18 hours of mechanical ventilation. Real-time polymerase chain reaction analyses revealed that mechanical ventilation, in comparison with time-matched controls, did not alter diaphragmatic levels of Type I and IIx myosin heavy chain messenger ribonucleic acid levels in the diaphragm. These data support the hypothesis that mechanical ventilation results in a decrease in both mixed muscle protein and myosin heavy chain protein synthesis in the diaphragm. Further, the decline in myosin heavy chain protein synthesis does not appear to be associated with a decrease in myosin heavy chain messenger ribonucleic acid.

Effects of Antioxidant Therapy in Women Exposed to Eccentric Exercise

The purpose of this study was to determine the effects of antioxidant therapy on indirect markers of muscle damage following eccentric exercise (EE). Eighteen women were randomized to an antioxidant supplement or a placebo before a bout of EE. Plasma creatine kinase (CK) activity, muscle soreness (MS), maximal isometric force (MIF), and range of motion (ROM) were assessed before and through 14 d postexercise. Eccentric exercise resulted in an increase in CK activity and MS, and a drop in MIF and ROM during the days following EE, which returned to baseline values 14 d after EE in both groups. Antioxidants attenuated the CK activity and MS response to the EE, while little difference was noted between groups in MIF or ROM. These fndings suggest that antioxidant supplementation was helpful in reducing the elevations in plasma CK activity and MS, with little impact on MIF and ROM loss.

Cumulative Effects of Aging and Mechanical Ventilation on In Vitro Diaphragm Function

STUDY OBJECTIVE

Unloading the diaphragm, via mechanical ventilation (MV), results in significant diaphragmatic atrophy, contractile dysfunction, and oxidative stress in young adult animals. Since aging increases skeletal muscle susceptibility to atrophy and injury, we tested the hypothesis that MV-induced diaphragmatic contractile dysfunction would be exacerbated in aging rats.

METHODS

Fisher 344/Brown Norway hybrid rats (4 months old [young] and 30 months old [old]) were assigned to either control or MV groups. MV rats were anesthetized, tracheostomized, and ventilated with 21% O(2) for 12 h. Arterial BP, pH, and blood gas homeostasis were maintained in the MV animals throughout the experimental period. Animals in the control group were acutely anesthetized, and the diaphragms were immediately removed. Muscle strips from the mid-costal diaphragm were removed from each experimental animal, and contractile properties were studied in vitro.

RESULTS

Compared to young control animals, aging (old control animals) was associated with a 13% decrease in maximal isometric tension (24.5 N/cm(2) vs 21.3 N/cm(2)). Although, MV induced similar relative losses (24%) in diaphragmatic isometric tension in both young and old animals receiving MV, the combined effects of aging and MV resulted in a 34% decrement in diaphragmatic isometric tension compared to young control animals (24.5 N/cm(2) vs 16.1 N/cm(2)).

CONCLUSIONS

These data do not support the hypothesis that aging exacerbates the relative MV-induced impairment in diaphragmatic isometric tension. Nonetheless, the additive effects of aging and MV have dramatic effects on diaphragmatic force reserve. This could exacerbate weaning difficulties in older individuals receiving MV.

Mechanical ventilation-induced oxidative stress in the diaphragm

Prolonged mechanical ventilation (MV) results in oxidative damage in the diaphragm; however, it is unclear whether this MV-induced oxidative injury occurs rapidly or develops slowly over time. Furthermore, it is unknown whether both soluble (cytosolic) and insoluble (myofibrillar) proteins are equally susceptible to oxidation during MV. These experiments tested two hypotheses: 1). MV-induced oxidative injury in the diaphragm occurs within the first 6 h after the initiation of MV; and 2). MV is associated with oxidative modification of both soluble and insoluble proteins. Adult Sprague-Dawley rats were randomly divided into one of seven experimental groups: 1) control (n = 8); 2) 3-h MV (n = 8); 3). 6-h MV (n = 6); 4). 18-h MV (n = 8); 5). 3-h anesthesia-spontaneous breathing (n = 8); 6). 6-h anesthesia-spontaneous breathing (n = 6); and 7). 18-h anesthesia-spontaneous breathing (n = 8). Markers of oxidative injury in the diaphragm included the measurement of reactive (protein) carbonyl derivatives (RCD) and total lipid hydroperoxides. Three hours of MV did not result in oxidative injury in the diaphragm. In contrast, both 6 and 18 h of MV promoted oxidative injury in the diaphragm, as indicated by increases in both protein RCD and lipid hydroperoxides. Electrophoretic separation of soluble and insoluble proteins indicated that the MV-induced accumulation of RCD was limited to insoluble proteins with molecular masses of approximately 200, 120, 80, and 40 kDa. We conclude that MV results in a rapid onset of oxidative injury in the diaphragm and that insoluble proteins are primary targets of MV-induced protein oxidation.

Novel Synthesis of Bis(phosphonic acid)−Steroid Conjugates

An efficient synthesis has been realized for several members of a new class of potential bone resorption inhibitors consisting of steroidal oestrogenic units linked at the 3 and 17 positions to a geminal bisphosphonate moiety through an ester linkage of variable length. The convergent synthesis utilizes benzyl bisphosphonates, transesterification, and Meldrum's acid chemistry and has the potential to allow many oestrogenic derivatives as well as other biologically active compounds to be coupled to the geminal bisphosphonate moeity.

Symptom patterns in long-duration chronic fatigue syndrome

OBJECTIVE

Our objective was to evaluate symptom patterns in patients with chronic fatigue syndrome (CFS) who were ill for 10 or more years.

METHODS

This cross-sectional self-report study compared patient groups with long-duration (median = 18 years; n = 258) and short-duration (median = 3 years; n = 28) CFS to a group of healthy significant others (n = 79) on symptomatic, neurocognitive, and psychological variables. Data were gathered from a 574-item postal questionnaire.

RESULTS

A principal-components analysis of CFS symptom data yielded a three-factor solution: cognitive problems; flu-like symptoms; and neurologic symptoms. Compared with the short-duration CFS group, the long-duration group had significantly higher CFS symptom severity scores (p < 0.04), largely attributable to increased cognitive difficulties. A subgroup comparison of subjects ill for < 3 years versus those ill 4-7 years suggested that denial coping strategies were more likely in those participants with the shorter illness duration. Significant differences between both CFS groups and healthy controls were found in a number of comorbid disorders. Participants with CFS most often endorsed immune/viral abnormalities and persistent stress as important perceived causes of their illness.

CONCLUSION

Participants with long-duration CFS reported a large number of specific cognitive difficulties that were greater in severity than those reported by participants with short-duration CFS. The pattern of comorbid disorders in the CFS groups was consistent with hypersensitivity and viral reactivation hypotheses.

Modified ELISA for the detection of neomycin phosphotransferase II in transformed plant species

 Identifying transformed plant lines carrying the antibiotic resistance marker gene, neomycin phosphotransferase II, requires a more definitive test than the ability of the plant to grow on kanamycin. Although a number of alternative assays have been described, most are cumbersome, time consuming and/or require the use of radioisotopes. This report describes an ELISA for the detection of the neomycin phosphotransferase II enzyme in transformed plant tissue. The ELISA utilises commercially available antibodies and provides a number of advantages, including an extremely low background, a reduction in the amount of tissue required for testing, and semi-quantitative data on neomycin phosphotransferase II gene expression. This method has been applied successfully to a number of independently transformed lines in nine plant species.

Influence of white clover mosaic potexvirus infection on the endogenous cytokinin content of bean

The cytokinin content in the primary leaves of bean (Phaseolus vulgaris) was monitored for 10 d after inoculation with white clover mosaic potexvirus. The cytokinins were isolated, purified, separated by high-performance liquid chromatography, and quantified by radioimmunoassay. The cytokinins detected at the time of inoculation (d 0) were: (a) the free bases, zeatin (Z), dihydrozeatin (DZ), and isopentenyladenine; (b) the riboside, DZ riboside (DZR); (c) the O-glucosides of DZ, DZR, and Z riboside; (d) the nucleotides, Z riboside-5'-monophosphate and isopentenyladenosine-5'-monophosphate; and (e) trace amounts of Z-9-glucoside and DZ-9-glucoside. During the 10 d after inoculation with white clover mosaic potexvirus, marked quantitative changes in this cytokinin profile were observed. The concentration of the free bases and DZR decreased, accompanied by an increase in the 9-glucosides and the nucleotides. Virus titer increased rapidly 3 d after inoculation, attaining a maximum level at d 5. This increase coincided with the increases in the 9-glucosides and the nucleotides. We propose that the decline in the cytokinin free bases and riboside may allow the increase of virus titer in bean and lead to the senescence of infected leaves.

Controlled cytokinin production in transgenic tobacco using a copper-inducible promoter

The cytokinin group of plant hormones regulates aspects of plant growth and development, including the release of lateral buds from apical dominance and the delay of senescence. In this work the native promoter of a cytokinin synthase gene (ipt) was removed and replaced with a Cu-controllable promoter. Tobacco (Nicotiana tabacum L. cv tabacum) transformed with this Cu-inducible ipt gene (Cu-ipt) was morphologically identical to controls under noninductive conditions in almost all lines produced. However, three lines grew in an altered state, which is indicative of cytokinin overproduction and was confirmed by a full cytokinin analysis of one of these lines. The in vitro treatment of morphologically normal Cu-ipt transformants with Cu2+ resulted in delayed leaf senescence and an increase in cytokinin concentration in the one line analyzed. In vivo, inductive conditions resulted in a significant release of lateral buds from apical dominance. The morphological changes seen during these experiments may reflect the spatial aspect of control exerted by this gene expression system, namely expression from the root tissue only. These results confirmed that endogenous cytokinin concentrations in tobacco transformants can be temporally and spatially controlled by the induction of ipt gene expression through the Cu-controllable gene-expression system.