Defense Mechanisms of the Lungs

Abstract

·:·1133Nonviable particles enter the atmosphere from forest fires, wind action on dessicated soil, entrainment of sea spray, volcanic debris, and gas phase reactions. Man-made sources account for approximately 185-415 X 106 metric tons per year out of an estimated total of 985-26 15 X 106 metric tons per year and are generated from less than 1% of the earth's surface (6 1, 83, 195). The size of the particle is the single most important feature of an aerosol because it determines the stability of the aerosol. The largest size, highest concentration, and greatest diversity in source and composition of particles occurs in the troposphere immediately above the surface of the earth. Although size and concentration of particles tend to decrease with altitude (and distance from urban centers), gas phase reactions activated by sunlight generate large numbers of new particles between 1000-3000 ft in the troposphere and 60,000--65,000 ft in the stratosphere (6 1). These reactions involve hydrocarbons and oxides of nitrogen from man-made pollution over cities, yielding complex mixtures of nitrogen dioxide, ozone, formaldehyde, ketones, peroxyacyl nitrates, carbon monoxide, etc (4). Although only 35% of the total weight of the particles in this urban aerosol is in the submicronic range, this size range contains the largest number of particles with the largest surface area. Such small size assures deep penetration into the lung, but also favors adsorption of gas by the particle, thus enhancing its capacity to potentiate reactions to irritant gases by causing a high local concentration (44). Although aerosols inside urban buildings are predominantly smaller in size than aerosols outside buildings and so increase the risk for the occupants, most urban aerosols are monitored only outside buildings 'Annu. Rev. Physiol. 1975.37:325-350. Downloaded from www.annualreviews.org Access provided by Western Michigan University on 02/03/15. For personal use only.Quick links to online content Further ANNUAL REVIEWS

The effects of age and carbon black on airway resistance in mice

“…Based on the results of this study, the effect of acute CB exposure at 67 wks appeared to be limited to the conducting airways without causing changes in the lung parenchyma. In a review by Cohen and Gold (1975) {Cohen, 1975 #126}, the authors indicated that deposition of particles in upper airways results in constriction without affecting compliance. This concept of particle deposition seems to be consistent with the current results in mice indicating that acute effects of CB exposure were related to changes in the upper airways compared to distal changes in the lung parenchyma.…”

Detection and partial characterization of antibacterial factor(s) in alveolar lining material of rats.

“…Purified diacylphospholipids had no antibacterial activity, however, a lysophospholipid, palmitoyl lysophosphatidylcholine, had many properties resembling the surfactant-containing fraction of lavage, including autolysin-mediated pneumococcal lysis, altered cell membrane permeability, and antibacterial activity against several gram-positive bacteria. INTRODUCTION It is frequently stated that inhaled bacteria are killed by alveolar macrophages (1,2). This view is based (10).…”

Macrophage activation, chronic inflammation and gastrointestinal disease.

“…38 Various inorganic materials such as beryllium, barium salts, zirconium and silica are localised within tissues, often within macrophages. This eventually results in granulomatous and excessive fibrotic reactions.…”