Experimental infective pneumoconiosis: Effect of asbestos dust and Candida albicans infection on the lungs of rhesus monkeys

Our plain-English summary of Experimental infective pneumoconiosis: Effect of asbestos dust and Candida albicans infection on the lungs of rhesus monkeys, by S. H. Zaidi, R. Shanker, R. K. S. Dogra (1973).

The study

• Authors: S. H. Zaidi, R. Shanker, R. K. S. Dogra
• Published: Environmental Research 6, 271-286 (1973)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

In this animal experiment in India, the authors injected rhesus monkeys through the windpipe with amosite asbestos dust alone, the yeast Candida albicans alone, or both. The article says seventy-eight were injected, after two of 80 were discarded for a positive tuberculin test. However, the group sizes it lists, 20, 26 and 26, add up to 72. Animals were examined at intervals up to 330 days. The yeast alone caused acute inflammation early on. By 330 days only a few small fibrotic spots remained and most lung tissue had regained its normal structure. Live yeast was not recovered from 90 days on. Amosite alone produced marked fibrosis around airways and blood vessels by 330 days, with numerous asbestos bodies. The combination produced diffuse collagen fibrosis, which the authors described as altogether different from that seen with either exposure alone. Live yeast was still found in this group at 120 days. The authors concluded that extensive lung fibrosis with dust is linked not only to tubercle bacilli but also to infections such as C. albicans. They said the mechanism was not clearly understood and needs further study.

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: intratracheal injection of amosite dust, Candida albicans, or both into rhesus monkeys, with animals sacrificed at intervals for lung pathology and yeast counts
• Who was studied: 80 locally obtained rhesus monkeys (Macaca mulatta) with an average body weight of 4 kg. Two tuberculin-positive animals were discarded, and the article states that seventy-eight were injected in three groups. The group sizes listed (20, 26 and 26) add up to 72, not 78. Animals were sacrificed from immediately after inoculation up to 330 days.
• Exposure: Indian amosite asbestos dust (1 g per animal in 10 ml sterile saline), Candida albicans (stated as 1 mg per animal in the dose-finding section), or both combined, given by intratracheal injection
• Main results:
  • Candida albicans alone (Group I): at 330 days a few isolated fibrotic foci persisted, but most of the lung tissue regained its normal architecture
  • Candida albicans alone: viable counts did not show organisms from 90 days onward
  • Amosite dust alone (Group II): severe lesions by 330 days after inoculation, described as dense fibrosis around bronchioles and blood vessels with moderate interstitial fibrosis
  • Amosite dust alone: viable counts for yeast in the lung were negative at all periods
  • Amosite dust plus Candida albicans (Group III): at 330 days, diffuse fibrosis of collagen and thick reticulin fibers, with well-developed collagenous interlobular adhesions
  • Combined group: the authors described the extensive fibrosis as altogether different from that seen with amosite dust or C. albicans alone
  • Combined group: viable yeast was present at 120 days; counts were negative from 150 days on
• The authors' conclusion: The authors concluded that extensive pulmonary fibrosis in the presence of dust is related not only to tubercle bacilli, as they had reported earlier, but also to other infections such as C. albicans. They said that how far such an organism accentuates the fine fibrosis of asbestosis remains to be investigated.
• Limitations the authors state:
  • The authors said the mechanism behind the extensive fibrosis in the combined group cannot be clearly understood from these experiments and requires further investigation
  • The authors said the severity of the amosite lesions may reflect the injection technique, the large amount of dust given, or a species difference
  • The authors said it is unclear whether the fibrosis in the Candida-only group came from live organisms or from their metabolites after viable counts became negative

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Amosite, Inflammation, Fibrosis, Asbestos Bodies, Collagen.

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