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Assessment of oxidative stress status (OSS) in human tissues is still troublesome. Using an innovative EPR-radical-probe we successfully measured the instantaneous concentration of ROS directly in peripheral blood of athletes and normally active workers during 60 min controlled exercise. The probe employed was bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate, which quantitatively and instantaneously reacts with oxygen-centered radicals (including superoxide) to yield the parent nitroxide, which is sufficiently persistent to be measured by EPR. Our measurements suggest that while at rest normally active individuals may benefit more from antioxidant supplementation than athletes; conversely, during exercise athletes may benefit more from supplementation. Our method allows reliable, quick, and non-invasive quantitative determination of OSS in human peripheral blood. [ABSTRACT FROM AUTHOR]

The role of reactive oxygen species (ROS) in liver disease is controversial. This mostly reflects the difficulties to quantify ROS in vivo , particularly in humans. We aimed to measure the presence of ROS in diseased human liver and identify possible relations between ROS levels and etiology, histology and hepatocyte proliferation. Liver biopsy specimens from 102 individuals: 18 healthy controls and 84 patients (42 HCV chronic hepatitis (CHC), 19 HBV chronic hepatitis (CHB), 7 PBC, 4 PSC, 4 HCV relapsing hepatitis after liver transplantation, 3 autoimmune hepatitis, 3 hepatocellular carcinoma, 2 alcoholic hepatitis) underwent analysis by radical-probe electron paramagnetic resonance (EPR). ROS in patients (median=5×10 -6 mmol/mg) were higher than in controls (median=3×10 -11 mmol/mg) ( p <0.001). Progressively increasing levels of ROS were recorded passing from control values to CHB (median=4×10 -7 mmol/mg), CHC (median=3×10 -6 mmol/mg) and PBC (median=2×10 -5 mmol/mg), the differences being significant ( p <0.001). ROS in CHC positively correlated with histological disease activity ( r =0.92; p <0.001). No correlation was found between ROS and hepatocyte proliferation rate, presence/degree of steatosis, serum ferritin levels and aminotransferases. ROS overproduction in liver appears to be a common thread linking different pathologic conditions and seems to be influenced by diseases' etiologies. [ABSTRACT FROM AUTHOR]