Postischemic myocardial contractile dysfunction is in part mediated by the burst of reactive oxygen species (ROS), which occurs with the reintroduction of oxygen. We hypothesized that tissue oxygen tension modulates this ROS burst at reperfusion. After 20 min of global ischemia, isolated rat hearts were reperfused with temperature-controlled (37.4 degrees C) Krebs-Henseleit buffer saturated wit...

Melatonin, the chief secretory product of the pineal gland, is an uncommonly effective direct free radical scavenger and indirect antioxidant. It detoxifies both reactive oxygen (ROS) and reactive nitrogen species (RNS), both groups of which are abundantly produced in the brain. Endogenously-generated melatonin is discharged from pinealocytes into the rich capillary plexus in the gland and may ...

Melatonin plays several important physiological functions in mammals, such as immune enhancement and regulation of dark-light signal transduction. Melatonin is also known to be an endogenous free radical scavenger and an efficient antioxidant. It detoxifies a variety of free radicals and reactive oxygen intermediates, including the hydroxyl radical, singlet oxygen and nitric oxide. These radica...

Preterm infants are vulnerable to the oxidative stress due to the production of large amounts of free radicals, antioxidant system insufficiency, and immature oligodendroglial cells. Reactive oxygen species (ROS) play a pivotal role in the development of periventricular leukomalacia. The three most common ROS are superoxide (O2(•-)), hydroxyl radical (OH(•)), and hydrogen peroxide (H2O2). Under...

Iron promotes DNA damage by catalyzing hydroxyl radical formation. We examined the effect of chromatin structure on DNA susceptibility to oxidant damage. Oxygen radicals generated by H2O2, ascorbate and iron-ADP (1:2 ratio of Fe2+:ADP) extensively and randomly fragmented protein-free DNA, with double-strand breaks demonstrable even at 1 microM iron. In contrast, polynucleosomes from chicken ery...

Melatonin plays several important physiological functions in mammals, such as immune enhancement and regulation of dark-light signal transduction. Melatonin is also known to be an endogenous free radical scavenger and an efficient antioxidant. It detoxifies a variety of free radicals and reactive oxygen intermediates, including the hydroxyl radical, singlet oxygen and nitric oxide. These radica...

Induction of oxidative stress and possible involvement of antioxidants in rice (Oryza sativa L) leaves after in vivo treatment with hydrogen peroxide (H 2 O 2) was investigated. Degradation of chlorophyll, carotenoid and protein contents in rice leaves was observed which showed a recovery under free radical scavenger treatments. An increase in both total peroxide accumulation and lipid peroxida...

The gas-phase reactions of ozone with alkenes can be significant sources of free radicals (OH, HO2 and RO2) in the Earth’s atmosphere. In this study the total radical production and degradation products from ethene ozonolysis have been measured, under conditions relevant to the troposphere, during a series of detailed simulation chamber experiments. Experiments were carried out in the European ...