Markers Of Free Radical Damage Research Articles

Ascorbyl radical formation in patients with sepsis: Effect of ascorbate loading

Patients with sepsis have low concentrations of antioxidants, including ascorbic acid, and also have increased concentrations of markers of free radical damage. Although ascorbic acid is a potent antioxidant, it can act as a prooxidant by promoting iron-catalysed reactions. We measured baseline total vitamin C and bleomycin-detectable “free” iron levels and ascorbyl radical concentrations before and after intravenous infusion of 1 g ascorbic acid in patients with sepsis and healthy control subjects. Vitamin C concentrations were decreased in patients compared to healthy subjects ( p<0.0001), and “free” iron was increased ( p < 0.002). Preinfusion ascorbyl radical concentrations were not different in patients and controls. Postinfusion ascorbyl radical levels increased in both controls and patients, with larger increases in healthy subjects ( p < 0.0001), suggesting suboptimal basal vitamin C levels and increased scavenging of a constant oxidant pool by ascorbate in the controls. In the patients, who were all vitamin C deficient, infused ascorbate was rapidly consumed, either via the promotion of redox cycling of iron or as a result of radical scavenging. This study demonstrates markedly different handling of infused ascorbate in patients with sepsis and healthy subjects, and further studies are needed to elucidate the relative anti- and pro-antioxidant mechanisms of ascorbate in patients with raised “free” iron levels.

Evidence for Increased oxidative Damage in Patients with Cystic Fibrosis

Patients with cystic fibrosis (CF) may be more susceptible to oxidative cell injury than normal healthy children due to both the impaired absorption of antioxidant nutrients and the increased oxidative stress caused by chronic pulmonary infections. The purpose of this study was to examine whether markers of oxidative damage to lipids (malondialdehyde-like substances and lipid hydroperoxides) and proteins (protein carbonyls) were present in the plasma of CF patients. Mean values (+/- SD) of thiobarbituric acid-reactive substances were significantly higher in patients (6.93 +/- 1.47 mumol/L; n = 25) than in controls (5.84 +/- 0.59 mumol/L; n = 10). FFA hydroperoxides were not detected in control subjects (the detection limit of the assay was 0.02 mumol/L), but in 11 of the 33 CF patients studied they were found in a range of 0.03-0.34 mumol/L. Plasma protein carbonyl concentrations did not differ significantly between the two groups (p = 0.076), although a much wider distribution was observed in the CF patients (range 0.17-5.64 nmol/mg protein) than in the control group (range 0.24-1.55 nmol/mg protein). No correlation was found between thiobarbituric acid-reactive substances and FFA hydroperoxides or between either of these markers and protein carbonyl content. Concentrations of plasma vitamin E, vitamin C, and protein sulfhydryls were within the normal ranges in both control subjects and CF patients. The concentration of uric acid was significantly reduced (p < 0.01) in the CF group (204 +/- 96.99 mumol/L) compared with that in control subjects (352 +/- 81.11 mumol/L), but reduction in plasma levels of this antioxidant did not correlate with increased markers of free radical damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on cervical intraepithelial neoplasia: The level of octadeca-9,11-dienoic acid and measurement of free radical content by electron spin resonance spectroscopy

The efficacy of electron spin resonance spectroscopy (a technique that measures free radicals) in detecting cervical intraepithelial neoplasia was evaluated in 68 women. In addition, electron spin resonance spectroscopic data were correlated with the phospholipid-esterified octadeca-9,11-dienoic acid (18:2(9,11))/octadeca-9,12-dienoic acid (18:2(9,12)) molar ratio, a suggested marker of free radical damage to linoleic acid. Incubation of cervical epithelial cells with the spin-trap N-tert-butyl-a-phenylnitrone and subsequent examination by electron spin resonance spectroscopy gave signals from a nitroxide radical, which has been tentatively assigned to an adduct from either a carbon-centered lipid radical or a lipid alkoxyl radical; no significant differences in either the type of radical detected or the intensity of the signals was found between patients with cervical intraepithelial neoplasia and normal control subjects. There was no significant correlation between the intensity of the electron spin resonance signal and the phospholipid-esterified 18:2(9,11)/18:2(9,12) molar ratio. This finding provides no support for the classification of 18:2(9,11) as a "free radical product."

Potential markers of free radical damage to DNA

Potential markers of free radical damage to DNA