A unified theory of cell differentiation, aging, and cancer is discussed. All cells are hypothesized to originate from stem cells. These stem cells mature as they divide and eventually reach a fully differentiated cell, which cannot divide. Aging is caused by the loss of stem cells, either due to cell death or terminal differentiation, and by eventual death of fully differentiated cells. Both l...

BACKGROUND Oxygen-derived free radicals are thought to injure the ischemic heart during coronary microvascular embolization. METHODS AND RESULTS To test this idea, microspheres (15 microns in diameter) were repetitively administered into the left anterior descending coronary artery to cause microvascular embolization in dogs. Myocardial contractile and metabolic dysfunctions were significantl...

Background. Oxygen-derived free radicals are thought to injure the ischemic heart during coronary microvascular embolization. Methods and Results. To test this idea, microspheres (15 gm in diameter) were repetitively administered into the left anterior descending coronary artery to cause microvascular embolization in dogs. Myocardial contractile and metabolic dysfunctions were significantly att...

The formation ofcis-l,2-dihydroxy-l,2,-dihydronaphthalene from naphthalene by naphthalene oxygenase, purified from Corynebacterium renale ATCC 15075, was demonstrated to involve oxidation of a mol NADH and consumption of one mol oxygen. The enzyme contains one g-atom Fe and one FAD. Catalase inhibited product formation and H2O2 could substitute for NADH in the reaction. Superoxide dismutase inh...

PURPOSE Retinal ganglion cells (RGCs) die as a result of axonal injury in a variety of optic neuropathies, including glaucoma. Reactive oxygen species (ROS) act as intracellular signaling molecules and initiate apoptosis in nerve growth factor-deprived sympathetic neurons and axotomized RGCs. Determination of the role of specific ROS relies on the use of small molecule or protein scavengers wit...

The antioxidant and radical scavenging properties of 8-oxo derivatives of pentoxifylline, lisofylline, enprofylline (3-propyl xanthine), and 1,7-dimethyl enprofylline were studied in vitro. The results show that 8-oxopentoxifylline and 8-oxolisofylline are significantly better hydroxyl and peroxyl radical scavengers and more potent inhibitors of t-butylhydroperoxide-induced lipid peroxidation i...

In the presence of NADH- reductases (dihydrolipoamide: NAD oxidoreductase E. C.1.8.1.4 from pig heart or from Clostridium kluyveri; frequently also addressed as "diaphorases") and NADH lucigenin strongly increases ethylene production from a-keto-methylthiobutyrate (KMB) as an indicator for strong oxidants of the OH-radical type. These reactions are further stimulated in the presence of Fe3+ ion...

A major impediment to the confirmation of free radical mechanisms in pathogenesis is a lack of direct, chemical evidence that oxygen centered free radicals actually arise in living tissues in quantities sufficient to cause serious damage. This investigation was conducted to validate the use of dimethyl sulfoxide (DMSO) as a quantitative molecular probe for the generation of hydroxyl radicals (H...

It has been proposed that xanthine oxidase-derived superoxide mediates reperfusion injury in the liver; however, there is a little direct evidence to support this hypothesis. In this paper we describe a model system to directly and noninvasively measure oxyradical formation and hepatic injury in isolated perfused rat liver. Using this sensitive chemiluminescent technique, we clearly demonstrate...

The photodynamic action of riboflavin is generally considered to involve the generation of reactive oxygen species, whose production is enhanced when Cu(II) is present in the reaction. In the present study we report that photoactivated riboflavin causes K(+) loss from fresh human red blood cells (RBC) in a time dependent manner. Addition of Cu(II) further enhances the K(+) loss and also leads t...