Asbestos dust as a nucleation center in the calcification of old fibrous tissue lesions, and the possible association of this process to the formation of asbestos bodies

Our plain-English summary of Asbestos dust as a nucleation center in the calcification of old fibrous tissue lesions, and the possible association of this process to the formation of asbestos bodies, by J.M. Davis (Experimental and Molecular Pathology, 1970).

The study

• Author: J.M. Davis
• Journal: Experimental and Molecular Pathology
• Published: 1970;12(2):133-47
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The intrapleural injection of chrysotile asbestos dust into the pleural cavity of guinea pigs results in the formation of fibrous lesions which eventually calcify to produce calcified plaques very similar to those found in human cases of asbestosis. The first stage in the process of calcification involves the coating of all the asbestos dust that remains among the collagen fibrils of the lesion with a thick coating of material that appears to be some form of acid mucopolysaccharide. Later, calcium, in the form of apatite crystals, is laid down. The initial deposition of apatite is on the surface of the mucopolysaccharide, but gradually all the spaces between the coated dust particles are filled with apatite crystals, and the lesion becomes completely calcified.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This was an animal experiment from the Department of Pathology at Cambridge University. The author injected 25 mg of chrysotile asbestos dust into the pleural cavity (the space around the lungs) of guinea pigs. The animals were killed at intervals from 14 days to 3 years later, and the resulting pleural lesions were examined under light and electron microscopes. The article does not state how many animals were used. Asbestos bodies (coated fibers) formed inside giant cells and could be seen within 2 weeks. Their number rose until about 6 weeks and then appeared to stay constant. By 18 months some lesions had begun to calcify, eventually producing calcified pleural plaques that the author described as very similar to those found in human asbestosis. Before calcification, every asbestos dust particle left among the collagen became thickly coated with a material that staining tests strongly indicated was an acid mucopolysaccharide. Calcium crystals (apatite) were usually first laid down on the surface of these coated particles. The author suggested that this coating material may be involved in the early stages of asbestos body formation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Animal experiment (intrapleural injection in guinea pigs, with light and electron microscopy of the lesions)
• Who was studied: Guinea pigs (number not stated), killed at intervals from 14 days to 3 years after injection; study carried out at the Department of Pathology, Cambridge University, England
• Exposure: A single injection of 25 mg of chrysotile asbestos dust in 1 ml of distilled water into the lower right pleural cavity. Most of the dust was in fiber bundles under about 5 micrometres long.
• Main results:
  • In the guinea pigs, asbestos bodies could be shown inside giant cells within 2 weeks of injection. Their number increased until about 6 weeks, after which the total appeared to remain constant.
  • By 18 months after injection, some fibrous lesions had started to calcify. Eventually this produced calcified pleural plaques described as very similar to those in human asbestosis.
  • When calcification occurred, large numbers of new laminated (layered) bodies appeared at the edges of the calcifying areas.
  • Staining tests strongly indicated that the material appearing in early calcification was a form of acid mucopolysaccharide.
  • Electron microscopy showed this material deposited as a thick layer around every asbestos dust particle remaining among the collagen fibrils.
  • Complete calcification of an area of fibrous tissue was found only after all the asbestos dust there had become coated with mucopolysaccharide.
• The authors' conclusion: The author concluded that the coating of asbestos dust with acid mucopolysaccharide during early calcification may indicate that this material is involved in the initial stages of asbestos body formation.
• Limitations the authors state:
  • The author states that where the additional laminated bodies form is uncertain.
  • The dust was sterilized by brief heating in water. The author only hoped that chemical changes from this heating were kept to a minimum.
  • The amount of fibrous tissue produced varied considerably between animals given the same dose.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Chrysotile, Pleural Cavity, Collagen, Fibril, Deposition.

Related studies

• The calcification of fibrous pleural lesions produced in guinea-pigs by the injection of chrysotile asbestos dust — J.M. Davis (1971)
• Further observations on the ultrastructure and chemistry of the formation of asbestos bodies — J.M. Davis (1970)
• Pleural calcification, pleural mesotheliomas, and bronchial cancers caused by tremolite dust — S. Yazicioglu, R. Ilçayto, et al. (1980)
• Prevalence of pleural calcification in persons exposed to asbestos dust, and in the general population in the same district — M. Navrátil, F. Trippé (1972)
• Epithelial outgrowths from lung tissue following intrapleural injection of asbestos dust in experimental animals — J.M. Davis (1971)
• The occurrence of pleural calcification among asbestos insulation workers — I.J. Selikoff (1965)

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