Ozone biochemical effects

Many studies have evaluated foe biochemical effects of ozone and other pollutants with whole-lung homogenates. This is a somewhat unsatisfactory approach, inasmuch as a toxic effect at a specific target site may... 

In a recent abstract, Hussain et al presented evidence that exposure of rats to ozone at 0.8 ppm for up to a week resulted in an increased rate of collagen thesis. Such a finding might be relevant to ozone-induced fibrosis. Obviously, further study of the biochemical effects of ozone on lung collagen and elastin are in order, particularly in conjunction with chronic-exposure experiments. 

A number of reviews of varied quality cover general or special effects of photochemical oxidants on vegetation (Table 11-1). Thomas fairly comprehensively covered the available information on the effects of photochemical oxidants on plants. Middleton gave the first comprehensive coverage of the phytotoxic effects of photochemical oxidants in 1961. A number of excellent reviews have appeared since 1%1. Rich presented an early review of ozone effects. Dugger and associates presented the physiologic and biochemical effects of oxidants on plants. Heck covered factors that influenced the expression of oxidant dam-... 

Biochemical Effects It is usual to find some changes in the chemical composition of plant tissue after exposure to ozone. One cannot be certain whether the changes are associated with early reactions to ozone or are merely delayed consequences of cell injury. 

Exposure to ozone biochemical reactkm from, 374 by plants. 10,437-38,440,447-54 cardnogenic effects <, 8, 363-65,433 controlled human studies on, 685 by measuring lung functions, 402-3, 407-8... 

The toxic effects of ozone in plant systems have been studied for some time, yet the actual mechanisms of injury are not fully understood. In addition to visible necrosis which appears largely on upper leaf surfaces, many other physiological and biochemical effects have been recorded ( ). One of the first easily measurable effects is a stimulation of respiration. Frequently, however, respiration may not increase without concomitant visible injury. Furthermore, photosynthesis in green leaves as measured by CO2 assimilation, may decrease. It is well known that ozone exposure is accompanied by a dramatic increase in free pool amino acids ( ). Ordin and his co-workers ( ) have clearly shown the effect of ozone on cell wall biosynthesis. In addition, ozone is known to oxidize certain lipid components of the cell ( ), to affect ribosomal RNA (16) and to alter the fine structure of chloroplasts (7 ). 

King, M. E. Biochemical Effects of Ozone. Ph.D. Thesis Illinois Institute of Technology, Chicago, Illinois. (1961). 

An effect of ozone on lung microsomes has been suggested by morpholine studies that indicated alterations in the endoplasmic reticulum, Biochemical evidence of an effect on microsomal enzymes was originally obtained in the studies of Palmer et who demonstrated that ozone exposure (0.75-10 ppm for 3 h) resulted in a decrease in activity of Syrian hamster lung benzopyrene hydroxylase, a mixed-function oxidase that depends on cytochrome P-450. No changes in hepatic activities of this enzyme were observed, and the results were similar in animals in which high activities of benzopyrene hydroxylase had been induced. The maximal effect was not observed until a few days after the single ozone exposure. Palmer et also reported a decrease in rabbit tracheobronchial mucosal benzopyrene hydroxylase activity after exposure to similar ozone concentrations. 

An appreciable body of evidence has accumulated to indicate that ozone has extrapulmonary effects. Although some of the reported effects may be secondary to the reaction of ozone with intrapulmonary neural receptors or to release of humoral substances from the lung, other finding appear to be mote directly related to an oxidizing effect of ozone. The biochemical basis for the latter is unclear, particularly because the reactivity of ozone and its short-lived intermediates would make it unlikely for them to penetrate the pulmonary parenchyma. Earlier studies on the subject of extrapulmonary effects have been reviewed by Stokinger. ... 

On the basis of the foregoing discussion, it appears that, if traditional criteria for hazard evaluation are applied to the toxicologic data on experimental animals, there is little room for complacency r arding current ambient concentrations of ozone. Functional, biochemical, and structural effects in both pulmonary and extrapulmonary sterns have been reported by numerous investigators at or near concentrations that are at least occasionally achieved in some polluted urban centers. Unfortunately, there are no adequate methods for extrapolating data to obtain reliable quantitative estimates of population risk at environmental concentrations near the standard, and there is no assurance that the risk is zero. 

Chang, C. W. Effect of ozone on sulfhydryl groups of ribosomes in pinto bean leaves. Relationship with ribosome dissociation. Biochem. Biophys. Res. Commun. 44 1429-1435, 1971. 

In recent years there has been increased interest in elucidating the biochemical and physiological responses of plants to air pollutants. Ozone has received particular scrutiny because of its importance in photochemical smog. The effects of ozone on the spectrum of physiological and biochemical systems has been analyzed in plant systems both vivo and vitro to... 

The major photochemically-produced atmospheric pollutant is ozone and, accordingly, most of the papers in this volume are concerned with this oxidant and its effects on plant processes, plant constituents such as cellular membranes, or on biochemical reactions common to the biological systems of plants and animals. I believe these authors have significant new answers to old questions, and I applaud them for their contributions. 

A combination of lime (10 g/L) and ozone (at 0.9 g/L) were found to be optimum to remove color from fermentation effluents, when neither alum nor biochemical oxidation were effective [79]. 

Nonliquefied compressed gases are of no use for pMDIs because liquid is needed for suspension of the dmg and the addition of water makes propulsion of the aerosol in an appropriate manner technically impossible. Hydrocarbons in general have the wrong density for use as propellants in pMDIs. While snitable as propellants for some nonmedicinal honsehold purposes, they are difhcult to use in a situation where dose reprodncibility is essential, and most are of course flammable and thus inappropriate for inhalation. The HCFCs are ozone-damaging and additionally have adverse toxicological effects on the heart and some biochemical hepatic functions. 

Smith, C. E. Stack, M. S. Johnson, D. A. Ozone effects on inhibitors of human neutrophil proteinases. Arch. Biochem. Biophys., 1987,253,146-155. 

In addition to increased mortality, human exposure to ozone in smog decreases pulmonary functions and initiates inflammatory processes in the lung. The biochemical basis of these effects is not very well established. One possible mechanism is attack by ozone on endogenous lipids that act as surfactants in the lung. 

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