The effects of dusts on peritoneal cells within diffusion chambers

Pulmonary toxicology of silica, coal and asbestos

Mineral particles are customarily inhaled as mixtures, though one component may predominate and determine the response. Although the lesions often possess a characteristic structure, according to the main type of particle deposited, morphology affords little indication of pathogenesis. Being a major element in the evolution of dust lesions, macrophage behavior has been examined extensively in vitro after treatment with mineral particles, attention being directed to membrane and biochemical changes; however, no clear lead to the origin of the lesions has emerged. Pulmonary fibrosis, as one of the ultimate consequences of dust accumulation, required a direct in vitro approach in which the products of the macrophage-particle interaction were utilized to provoke collagen formation by fibroblasts in a two-phase system. By this means, silica and asbestos stimulated connective tissue formation and application of the technique to coal dusts appears promising. Coal workers may develop a peculiar type of emphysema in relation to lesions whose fibrous content is comparatively small. Type II alveolar epithelium is also stimulated by inhaled particles and lipid accumulation follows. Alveolar lipidosis interferes with the fibrotic response by preventing contact between macrophage and particles. This phenomenon may account in part for anomalies, apparent in coal workers, between epidemiological findings and dust composition. Carcinogenesis is a well-recognized feature of asbestos exposure, but, as with fibrosis, risk prediction on the basis of in vitro tests of cytotoxicity is premature and may not be valid.

Crystal faces and cleavage planes in quartz as templates in biological processes

Some species of minerals, when comminuted and aerosolized in the form of respirable-size particulate dusts, are recognized as capable of producing disease in man after their inhalation. Comprehensive listings of such agents are in the current literature (e.g. in Aponte, 1970; Langer & Mackler, 1972; Ehrenreich et al. 1973a, b) and many of these and their effects are well known and receive much attention. Asbestos fibres of all varieties, ampbibole and quartz contaminated talcum powders (see Rohl et al. 1976), fibrous amphiboles and their cleavage fragments which contaminate the ambient environment (e.g., the contamination of Lake Superior with cummingtonite-grunerite, as discussed in Bowes, Langer & Rohl, 1977), have been the subject of recent intensive investigations mostly due to their protential impact to large segments of the general population.

Similarity in uptake and retention of trace amounts of 31 silicon and 68 germanium in rat tissues and cell organelles

Uptake of Si and Ge (chemical analogue of Si) in rat tissues was compared to establish their subcellular localization and determine if Ge could be used to trace Si in situ. 31Si and 68Ge were found in tissues and in cell organelles after injection of 31Si (OH) 4 or 68Ge (OH) 4. Accumulation of 31Si and 68Ge in the tissues increased for 30 minutes, declined rapidly about 30 minutes and then was gradually but steadily depleted. Simultaneous double labelling with 31Si and 68Ge produced concomitant accumulation and release of both isotopes. After a single IP injection, some 68Ge remained in the spleen and kidney for up to 20 days. The 31Si and 68Ge concentration in the tissues and cell organelles increased linearly with the amount administered (31Si, 10-4 to 10-2 g/kg body wt and 68Ge, 10-9 to 10-3 g/kg body wt). Thus, substitution of 68Ge for 31Si can extend the limit of detection of Si by at least 5 orders of magnitude. Both 31Si and 68Ge were water extractable (47%-74% and 38%-89%, respectively) from liver cell organelles; 45%-81% 31Si and 66%-90% 68Ge were extractable in 10% TCA, while only 10%-59% of either isotope were extractable in organic solvents (acetone, chloroform, ethanol). A small percentage of Si may be bound or polymerized.