THE PLACE OF ELECTRON-SPIN-RESONANCE METHODS IN THE DETECTION OF OXIDATIVE STRESS IN TYPE-2 DIABETES WITH POOR GLYCEMIC CONTROL

Objective: Chronic production of reactive oxygen species (ROS) and/or deficiency in the antioxidant defense system are observed in non-insul in-dependent diabetes mellitus (NIDDM) patients. As an adjunct to the usual indirect parameters for evaluating oxidative stress, we assessed the feasibility of oxyradicals detection in venous blood by electron spin resonance spectroscopy (ESR). Detection of the ascorbate pool was also performed using the validated ESR analysis of the ascorbyl free radical (AFR)-dimethyl sulfoxide (DMSO) complex. Methods and results: Plasma lipoperoxidation was characterized by higher levels of total MD A (1.50 +/- 0.08 nmol/L), lower levels of GSH (0.54 +/- 0.02 mmol/l)an d of vitamin A (2.13 +/- 0.52 mu mol/L) in the NIDDM group than in the controls (0.75 +/- 0.05 nmol/L, 0.90 +/- 0.05 mmol/L, 3.52 +/- 1.04 m u mol/L, respectively). Improvement of the ESR measurement of oxyradic al adducts has been previously obtained by addition of a new sensitive nitrone (DEPMPO), which acts as a spin-trap. However, in our experime nt the ESR signal-to-noise ratio was too low to detect significative o xyradicals adducts in total venous blood of NIDDM patients having a we ak production of ROS. A significant difference (p < 0.002) was observe d in DMSO/AFR index between controls (24.00 +/- 4.10 nmol/L) and NIDDM patients (7.28 +/- 2.36 nmol/L) suggesting ascorbate depletion relate d to the free radical production. Conclusion: The DMSO/AFR index could be an interesting additional marker of oxidative stress during a chro nic production of ROS. Copyright (C) 1998 The Canadian Society of Clin ical Chemists.