Overproduction of reactive oxygen and nitrogen species can result from exposure to environmental pollutants, such as ionising and nonionising radiation, ultraviolet radiation, elevated concentrations of ozone, nitrogen oxides, sulphur dioxide, cigarette smoke, asbestos, particulate matter, pesticides, dioxins and furans, polycyclic aromatic hydrocarbons, and many other compounds present in the environment. It appears that increased oxidative/nitrosative stress is often neglected mechanism by which environmental pollutants affect human health. Oxidation of and oxidative damage to cellular components and biomolecules have been suggested to be involved in the aetiology of several chronic diseases, including cancer, cardiovascular disease, cataracts, age-related macular degeneration, and aging. Several studies have demonstrated that the human body can alleviate oxidative stress using exogenous antioxidants. However, not all dietary antioxidant supplements display protective effects, for example, β-carotene for lung cancer prevention in smokers or tocopherols for photooxidative stress. In this review, we explore the increases in oxidative stress caused by exposure to environmental pollutants and the protective effects of antioxidants.

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There is debate concerning the time course and degree of r6coveV possible after relief of complete unilateral ureteric obstruction. This study in dogs investigates these features. One ureter was occluded for varying periods, and then reimplanted into the bladder. Recovery was monitored by Tc-Sn-labelled diethylene triarnine penta acetic acid (D.T.P.A.) scans and renograms together with creatinine clearance studies. The morphological changes were also studied. There was found to be a progressive loss of functional recovery with increasing periods of obstruction, though this was dramatically improved by contralateral nephrectomy once recovery had stabilized. Increased radial scarring developed in the kidney following increasing periods of obstruction.