Low pH does not modulate antioxidant status of diphenyl ditelluride but exacerbates Fe (II)-induced lipid peroxidation in liver preparation

Effects of Individualized Treadmill Endurance Training on Oxidative Stress in Skeletal Muscles of Transgenic Sickle Mice

Oxidative stress is a key feature in the pathophysiology of sickle cell disease. Endurance training has been shown to reduce oxidative stress in the heart and the liver of sickle mice. However, the effects of endurance training on skeletal muscles, which are major producers of reactive oxygen species during exercise, are currently unknown. The aim of this study was to evaluate the effect of sickle genotype on prooxidant/antioxidant response to individualized endurance training in skeletal muscles of sickle mice. Healthy and homozygous Townes sickle mice were divided into trained or sedentary groups. Maximal aerobic speed and V̇O₂ peak were determined using an incremental test on a treadmill. Trained mice ran at 40% to 60% of maximal aerobic speed, 1 h/day, 5 days/week for 8 weeks. Oxidative stress markers, prooxidant/antioxidant response, and citrate synthase enzyme activities were assessed in the gastrocnemius, in the plantaris, and in the soleus muscles. Maximal aerobic speed and V̇O₂ peak were significantly reduced in sickle compared to healthy mice (-57% and -17%; p < 0.001). NADPH oxidase, superoxide dismutase, and catalase activities significantly increased after training in the gastrocnemius of sickle mice only. A similar trend was observed for citrate synthase activity in sickle mice (p = 0.06). In this study, we showed an adaptive response to individualized endurance training on the prooxidant/antioxidant balance in the gastrocnemius, but neither in the plantaris nor in the soleus of trained sickle mice, suggesting an effect of sickle genotype on skeletal muscle response to endurance treadmill training.

One-Year Conservative Care Using Sodium Bicarbonate Supplementation Is Associated with a Decrease in Electronegative LDL in Chronic Kidney Disease Patients: A Pilot Study

Background

Chronic kidney disease (CKD) patients develop metabolic acidosis when approaching stages 3 and 4, a period in which accelerated atherogenesis may ensue. Studies in vitro show that low pH may increase low-density lipoprotein (LDL) oxidation, suggesting a role for chronic metabolic acidosis in atherosclerosis. The present study attempted to evaluate the effects of conservative care using oral sodium bicarbonate (NaHCO₃) supplementation on the electronegative LDL [LDL(-)], a minimally oxidized LDL, plasma levels in CKD patients.

Methods

Thirty-one CKD patients were followed by a multidisciplinary team during 15 months of care in which 1.0 mmol/kg/day oral NaHCO₃ supplementation was first given in the third month. Blood samples were collected 3 months before the initiation of oral NaHCO₃ supplementation (T1), at the time of the beginning of supplementation (T2), and thereafter, each 4 months (T3, T4 and T5) until month 15 of care. Blood parameters and LDL(-) were measured from these collections.

Results

After 12 months of conservative care, creatinine clearance (MDRD) was kept stable, and serum bicarbonate (HCO₃^-) increased from 20.5 ± 2.9 to 22.6 ± 1.1 mM (p < 0.003). LDL(-) plasma levels declined from 4.5 ± 3.3 to 2.1 ± 0.9 U/L (p < 0.007) after reaching mean serum HCO₃^- levels of 22.6 ± 1.1 mM.

Conclusions

Conservative care using oral NaHCO₃ supplementation was able to stabilize renal function and decrease serum levels of LDL(-), a modified proatherogenic lipoprotein, only when mean serum HCO₃^- levels approached 22 mM. This study constitutes evidence that alkali therapy, in addition to its beneficial effect on renal disease progression, might serve as a preventive strategy to attenuate atherogenesis in CKD patients.

Prooxidant/Antioxidant Balance in Hypoxia: A Cross-Over Study on Normobaric vs. Hypobaric "Live High-Train Low"

"Live High-Train Low" (LHTL) training can alter oxidative status of athletes. This study compared prooxidant/antioxidant balance responses following two LHTL protocols of the same duration and at the same living altitude of 2250 m in either normobaric (NH) or hypobaric (HH) hypoxia. Twenty-four well-trained triathletes underwent the following two 18-day LHTL protocols in a cross-over and randomized manner: Living altitude (PIO2 = 111.9 ± 0.6 vs. 111.6 ± 0.6 mmHg in NH and HH, respectively); training "natural" altitude (~1000-1100 m) and training loads were precisely matched between both LHTL protocols. Plasma levels of oxidative stress [advanced oxidation protein products (AOPP) and nitrotyrosine] and antioxidant markers [ferric-reducing antioxidant power (FRAP), superoxide dismutase (SOD) and catalase], NO metabolism end-products (NOx) and uric acid (UA) were determined before (Pre) and after (Post) the LHTL. Cumulative hypoxic exposure was lower during the NH (229 ± 6 hrs.) compared to the HH (310 ± 4 hrs.; P<0.01) protocol. Following the LHTL, the concentration of AOPP decreased (-27%; P<0.01) and nitrotyrosine increased (+67%; P<0.05) in HH only. FRAP was decreased (-27%; P<0.05) after the NH while was SOD and UA were only increased following the HH (SOD: +54%; P<0.01 and UA: +15%; P<0.01). Catalase activity was increased in the NH only (+20%; P<0.05). These data suggest that 18-days of LHTL performed in either NH or HH differentially affect oxidative status of athletes. Higher oxidative stress levels following the HH LHTL might be explained by the higher overall hypoxic dose and different physiological responses between the NH and HH.

Ventilation, oxidative stress, and nitric oxide in hypobaric versus normobaric hypoxia

PURPOSE

Slight differences in physiological responses and nitric oxide (NO) have been reported at rest between hypobaric hypoxia (HH) and normobaric hypoxia (NH) during short exposure.Our study reports NO and oxidative stress at rest and physiological responses during moderate exercise in HH versus NH.

METHODS

Ten subjects were randomly exposed for 24 h to HH (3000 m; FIO2, 20.9%; BP, 530 ± 6 mm Hg) or to NH (FIO2, 14.7%; BP, 720 ± 1 mm Hg). Before and every 8 h during the hypoxic exposures, pulse oxygen saturation (SpO2), HR, and gas exchanges were measured during a 6-min submaximal cycling exercise. At rest, the partial pressure of exhaled NO, blood nitrate and nitrite (NOx), plasma levels of oxidative stress, and pH levels were additionally measured.

RESULTS

During exercise, minute ventilation was lower in HH compared with NH (-13% after 8 h, P < 0.05). End-tidal CO2 pressure was lower (P < 0.01) than PRE both in HH and NH but decreased less in HH than that in NH (-25% vs. -37%, P < 0.05).At rest, exhaled NO and NOx decreased in HH (-46% and -36% after 24 h, respectively, P < 0.05) whereas stable in NH. By contrast, oxidative stress was higher in HH than that in NH after 24 h (P < 0.05). The plasma pH level was stable in HH but increased in NH (P < 0.01). When compared with prenormoxic values, SpO2, HR, oxygen consumption, breathing frequency, and end-tidal O2 pressure showed similar changes in HH and NH.

CONCLUSION

Lower ventilatory responses to a similar hypoxic stimulus during rest and exercise in HH versus NH were sustained for 24 h and associated with lower plasma pH level, exaggerated oxidative stress, and impaired NO bioavailability.

Fe(II) and sodium nitroprusside induce oxidative stress: a comparative study of diphenyl diselenide and diphenyl ditelluride with their napthyl analog

Here, we compare the influence of molecular structural modifications of diphenyl diselenide (DPDS) and diphenyl ditelluride (DPDT) with their naphthalene analogs, 1-dinapthyl diselenide (1-NapSe)2, 2-dinapthyl diselenide (2-NapSe)2, 1-dinapthyl distelluride (1-NapTe)2, and 2-dinapthyl ditelluride (2-NapTe)2. Fe(II)-induced hepatic thiobarbituric acid reactive species (TBARS) was in the order [(2-NapTe)2] > [(2-NapSe)2] > [(DPDS)] > [(1-NapSe)2] > [(1-NapTe)2]> [(DPDT)]. For sodium nitroprusside (SNP)-induced hepatic TBARS, the order was [(2-NapTe)2] > [(DPDT)] > [(1-NapSe)2] > [(2-NapSe)2] > [(1-NapTe)2] > [(DPDS)]. For Fe(II) and SNP-induced renal TBARS, the orders were [(2-NapTe)2] > [(1-NapTe)2] = [(DPDT)] > [(1-NapSe)2] > [(2-NapSe)2] > [(DPDS)] and [(2-NapTe)2] > [(1-NapTe)2] > [(1-NapSe)2] > [(2-NapSe)2] > [(DPDS)] > [(DPDS)], respectively. The present investigation shows that DPDS was less potent and the change in the organic moiety from an aryl to napthyl group dramatically changed the potency of diselenides. These results suggest that minor changes in the organic moiety of aromatic diselenides can profoundly modify their antioxidant properties. In view of the fact that the pharmacological properties of organochalcogens are linked, at least in part, to their antioxidant properties, it becomes important to explore the pharmacological properties of dinaphtyl diselenides and ditellurides.