ascorbic-acid and Myositis

We have previously shown that vitamin C supplementation affects recovery from an unaccustomed bout of demanding exercise, with the most pronounced effect being that on plasma interleukin-6 concentration. However, because of the proposed role of interleukin-6 in the regulation of metabolism, it was unclear whether this represented a reduced response to muscle damage or some form of interaction with the metabolic demands of the activity. Therefore, the aim of the present study was to investigate the effect of the same form of supplementation on a bout of exercise that initiated similar muscle damage but had a low metabolic cost. Fourteen male subjects were allocated to either a placebo (P) or a vitamin C (VC) group. The VC group consumed 200 mg of ascorbic acid twice a day for 14 days prior to a bout of exercise and for the 3 days after exercise. The P group consumed identical capsules that contained 200 mg lactose. Subjects performed 30 min of downhill running at a gradient of -18% and recovery was monitored for up to 3 days after exercise. Plasma VC concentrations in the VC group increased following supplementation. Nevertheless, downhill running provoked a similar increase in circulating markers of muscle damage (creatine kinase activity and myoglobin concentration) and muscle soreness in P and VC groups. Similarly, although downhill running increased plasma interleukin-6, there was no effect from VC supplementation. These results suggest that vitamin C supplementation does not affect interleukin-6 concentrations following eccentric exercise that has a low metabolic component.

Topics: Adult; Ascorbic Acid; Creatine Kinase; Dietary Supplements; Double-Blind Method; Exercise; Humans; Interleukin-6; Male; Muscle, Skeletal; Myoglobin; Myositis; Pain; Recovery of Function

There has been no investigation to determine if the widely used over-the-counter, water-soluble antioxidants vitamin C and N-acetyl-cysteine (NAC) could act as pro-oxidants in humans during inflammatory conditions. We induced an acute-phase inflammatory response by an eccentric arm muscle injury. The inflammation was characterized by edema, swelling, pain, and increases in plasma inflammatory indicators, myeloperoxidase and interleukin-6. Immediately following the injury, subjects consumed a placebo or vitamin C (12.5 mg/kg body weight) and NAC (10 mg/kg body weight) for 7 d. The resulting muscle injury caused increased levels of serum bleomycin-detectable iron and the amount of iron was higher in the vitamin C and NAC group. The concentrations of lactate dehydrogenase (LDH), creatine kinase (CK), and myoglobin were significantly elevated 2, 3, and 4 d postinjury and returned to baseline levels by day 7. In addition, LDH and CK activities were elevated to a greater extent in the vitamin C and NAC group. Levels of markers for oxidative stress (lipid hydroperoxides and 8-iso prostaglandin F2alpha; 8-Iso-PGF2alpha) and antioxidant enzyme activities were also elevated post-injury. The subjects receiving vitamin C and NAC had higher levels of lipid hydroperoxides and 8-Iso-PGF2alpha 2 d after the exercise. This acute human inflammatory model strongly suggests that vitamin C and NAC supplementation immediately post-injury, transiently increases tissue damage and oxidative stress.

Topics: Acetylcysteine; Adult; Antioxidants; Ascorbic Acid; Bleomycin; Creatine Kinase; Dinoprost; Double-Blind Method; Exercise; F2-Isoprostanes; Glutathione Peroxidase; Humans; Interleukin-6; Iron; L-Lactate Dehydrogenase; Lipid Peroxidation; Lipid Peroxides; Male; Muscle, Skeletal; Myoglobin; Myositis; Oxidative Stress; Pain; Peroxidase; Placebos; Superoxide Dismutase

The possible reason for elimination of myogenic cells after transplantation is inflammation at the injection site associated with oxidative stress. The aim of this study was to determine whether preconditioning of muscle-derived cells with an antioxidant, sodium ascorbate, can influence the fate of transplanted cells.. Autologous transplantation of muscle-derived cells was performed in rabbits. Isolated cells were identified, lipofected with β-galactosidase, preincubated or not with sodium ascorbate, and injected intramuscularly.. Two weeks after autologous transplantation in the edge of a previous muscle defect, donor cells formed multinucleated young myotubes. Pretreatment of cells with sodium ascorbate before injection resulted in a significant increase of donor cells at the injection site 2 weeks after transfer.. These results show that: (1) preincubation with antioxidant can increase the efficacy of myogenic cell transplantation; and (2) oxidative stress may play a role in elimination of cells after autologous transplantation.

Topics: Animals; Antioxidants; Ascorbic Acid; beta-Galactosidase; Cell Survival; Cell Transplantation; Cells, Cultured; Desmin; Disease Models, Animal; Green Fluorescent Proteins; Injections, Intramuscular; Muscle Fibers, Skeletal; Myositis; Oxidative Stress; Rabbits; Statistics, Nonparametric; Transfection; Transplantation, Autologous

Topics: Ascorbic Acid; Azathioprine; Blood Gas Analysis; Dapsone; Female; Follow-Up Studies; Humans; Hypercapnia; Hypoxia; Methemoglobinemia; Methylene Blue; Middle Aged; Myositis; Oximetry; Polysomnography; Prednisone; Respiratory Function Tests; Respiratory Insufficiency; Risk Assessment; Severity of Illness Index; Treatment Outcome

The plasma concentration of vitamin C of 14 patients with tropical pyomyositis without clinical evidence of scurvy and that of II age and sex-matched controls was determined in order to ascertain whether or not there was a deficiency of the vitamin in this condition. The results show that the mean plasma concentrations of vitamin C of patients were slightly higher (15.9 +/- 6.4 g/l) than those of controls (12.0 +/- 4.5 g/l). The differences, however, were not statistically significant (P greater than 0.25). It is therefore concluded that lack of vitamin C does not play a part in the aetiology of tropical pyomyositis.

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Humans; Myositis

Topics: Anti-Bacterial Agents; Ascorbic Acid; Humans; Myositis; Staphylococcal Infections; Suppuration; Tropical Medicine