p-aminobenzoic acid as a protective agent in ozone toxicity

Changes in lipids of lung lavage in monkeys after chronic exposure to ambient levels of ozone

A group of 8 sub-adult bonnet monkeys (Macaca radiata) was exposed to 0.3 ppm ozone (O3) and another group of 7 monkeys to 0.15 ppm O3 for 8 h/day for 90 days. A third group of 4 monkeys was exposed to 0.15 ppm O3 for 8 h/day for 21 days. The control group consisted of 7 monkeys which breathed filtered air for 90 days. Levels of linoleic and arachidonic acids in the total lipids from lung lavage increased about 2-fold in those exposed to O3 as compared to the levels in the controls. Furthermore, the relative level of cholesterol ester (CE) decreased and phosphatidylcholine (PC) increased markedly with chronic exposure of animals to O3. Enhanced polyunsaturated fatty acid (PUFA) composition in lung lavage and changes in the levels of CE and PC may be related to animals' adaptation to O3-exposure.

Ozone-induced formation of O,O'-dityrosine cross-linked in proteins

Treatment of spectrin, insulin, glucagon and ribonuclease with ozone results in covalent cross-linking of these proteins. This cross-linking is not reversed by treatment with dithiothreitol and thus can not be ascribed to -S-S- bond formation. A concomitant O,O'-dityrosine formation is observed by spectrofluorometric analysis of the protein and by amino acid analysis and thin-layer chromatography of hydrolyzed protein samples. It is highly probable that the observed protein cross-linking should be attributed to interpeptide O,O'-dityrosine bonds. Several authors have shown before that oxidation of proteins with horseradish peroxidase and H2O2 also leads to O,O'-dityrosine formation. Peroxidase-induced O,O'-dityrosine formation in galactose oxidase (d-galactose:oxygen 6-oxidoreductase, EC 1.1.3.9) causes a strong increase of enzyme activity. In accordance with these observations ozone treatment of galactose oxidase also leads to O,O'-dityrosine formation with a concomitant 8-fold increase of enzyme activity.

Ozone sensitivity in aging WI-38 cells based on acid phosphatase content

Young [16-19 population doubling level (PDL)] and senescing (50-53 PDL) WI-38 cell populations were exposed to 1 ppm ozone for 2 hr and the resultant extracellular and intracellular acid phosphatase concentration was measured. Dose-response curves were also determined for surviving populations of young and old cells after a 1 hr ozone exposure ranging in concentration from 0 to 1.00 ppm. Senescing cells released 8 times more acid phosphatase per million cells than the young cells. Both old and young cells showed a clear dose-response to the 1 hr ozone gradient exposure. However, the older cells demonstrated a consistent 17% average lower survival rate than the young cells. The higher acid hydrolase level in older WI-38 cells is probably related to the lower survival rate observed in the older cells in vitro.

Biochemical response of squirrel monkeys to ozone

Biochemical studies were performed on blood and lung tissue of squirrel monkeys (Saimiri sciureus) following acute exposure to 0.75 ppm ozone (O3) for 4 h/d for 4 consecutive days. One group of animals was sacrificed at the end of the last exposure day and another group was sacrificed 4 d later after the last exposure. Evidence was sought for oxidation-induced changes known to occur in rodents when high levels of O3 are inhaled. A significant increase in red blood cell membrane fragility was observed, as well as significant decreases in red blood cell glutathione and erythrocyte acetylcholinesterase; however, the red blood cell enzymes, lactic acid dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G6PDH) were not changed significantly. Lung tissue analysis showed that lipid peroxidation was markedly increased and tissue vitamin E levels were significantly decreased. The tissue enzymes G6PDH, glutathione reductase, and LDH significantly increased in activity. No significant changes were seen in either superoxide dismutase or malic acid dehydrogenase. The results of this experiment indicate that O3, or reaction products resulting from O3-tissue interaction in the lung, pass the air-blood barrier and are capable of producing biochemical changes in blood as well as in lung tissue.

Autoxidation of polyunsaturated fatty acids. Part I. Effect of ozone on the autoxidation of neat methyl linoleate and methyl linolenate

Neat samples of polyunsaturated fatty acids were exposed to ozone in air in a flow system, and the formation of peroxides, conjugated dienes and thiobarbituric acid (TBA)-reactive material was followed as a function of time. The effect of ozone is to shorten the induction period normally observed in autoxidation studies, but the ozone, at the concentrations used here (0-1.5 ppm), appears to have no effect on the rates of product formation after the induction period. During the induction period, increasing ozone concentrations give rise to substantially increased rates of peroxide (or materials which titrate like peroxide) formation, a slightly increased rate of conjugated diene formation, and no significant increase in the rate of production of TBA-reactive material. Vitamin E lengthens the induction period but appears to have no other effect. Some of these data are in conflict with earlier reports of Menzel et al.