Modified nucleosides in asbestos workers at high risk of malignant disease: results of a preliminary study applying discriminant analysis

Our plain-English summary of Modified nucleosides in asbestos workers at high risk of malignant disease: results of a preliminary study applying discriminant analysis, by S.J. Solomon, A. Fischbein, O.K. Sharma, et al (British Journal of Industrial Medicine, 1985).

The study

• Authors: S.J. Solomon, A. Fischbein, O.K. Sharma, E. Borek
• Journal: British Journal of Industrial Medicine
• Published: 1985;42(8):560-2
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Patients with asbestos related malignant mesothelioma excrete high levels of modified nucleosides in their urine. The purpose of the present report was to explore further the usefulness of measuring these breakdown products of transfer RNA (tRNA) in male asbestos insulation workers who are at high neoplastic risk but without clinical signs of malignancy. Modified nucleoside levels (psi, m'A, m'I, m2G, and ac4C) were used as discriminator variables in a computer generated discriminant function in which 96% of the controls and 95% of the insulation workers were correctly classified. It was also found, using a similar multiple regression model, that 10 of 13 were correctly classified as having normal chest radiographs and 27 of 30 asbestos exposed subjects as exhibiting alterations in either the parenchyma, pleura, or both. The results suggest that measuring modified nucleosides levels in the urine of asbestos exposed workers, and perhaps others exposed to carcinogenic agents, has the potential for identifying, through multivariate statistical techniques, individuals who are at high neoplastic risk.

In plain English

In this brief pilot report, the authors measured modified nucleosides, breakdown products of transfer RNA, in urine. They tested 47 male asbestos insulation workers (median age 59) without clinical signs of malignancy, from a larger US national survey. For comparison they tested 44 healthy men (median age 39). A computer discriminant analysis tested whether nucleoside levels sorted people into the correct group. Only people with complete results entered each analysis, so group sizes varied. Using two nucleosides, including pseudouridine, the analysis correctly classified 31 of 32 controls and 86% of workers (38 correct, 6 misclassified). Adding three more nucleosides, it correctly classified 96% of controls (27 correct, 1 misclassified) and 95% of workers (42 correct, 2 misclassified). Among exposed workers, it correctly identified 10 of 13 (77%) with normal chest X-rays and 27 of 30 (90%) with at least one abnormality. The controls were significantly younger; the authors cited earlier work finding nucleoside levels independent of age. The authors concluded that nucleoside levels accurately separated workers from controls and predicted X-ray abnormalities. They called their data preliminary, from a small subset.

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: Preliminary pilot study (brief communication) comparing urinary modified nucleoside levels in exposed workers and healthy controls, analysed by computer-generated discriminant analysis
• Who was studied: 47 male asbestos insulation workers (median age 59) without clinical signs of malignancy, a subset of a nationwide US longitudinal study; 44 healthy adult men as controls (median age 39)
• Exposure: Long-term occupational asbestos exposure as insulation workers; fiber types and doses not reported
• Main results:
  • Using pseudouridine and m'A levels alone, 31 of 32 controls were correctly classified (the text says a 98% hit rate; Table 1 prints 97%)
  • Using the same two nucleosides, 86% of asbestos workers were correctly classified (38 correct, 6 misclassified per Table 1), a 14% miss rate
  • After m'I, m2G and ac4C were added, 95% of asbestos workers (42 correct, 2 misclassified per Table 2) and 96% of controls (27 correct, 1 misclassified per Table 2) were correctly classified
  • Among exposed workers, 10 of 13 (77%) with normal chest radiographs and 27 of 30 (90%) with at least one radiographic abnormality (parenchyma, pleura, or both) were correctly classified
• The authors' conclusion: The authors concluded that discriminant analysis using modified nucleoside levels made it possible to predict accurately (1) asbestos insulation workers at high neoplastic risk but without clinical malignancy versus normal controls and (2) radiographic abnormalities in the exposed workers. They hypothesised an underlying gradient of biochemical events in asbestos-related disease.
• Limitations the authors state:
  • The authors described the data as preliminary and drawn from a small subset of the larger study group
  • Each analysis included only subjects with complete nucleoside profiles, which the authors said explains slight differences in numbers between tables
  • Controls and workers differed significantly in age (p less than 0.0001). The authors stated, citing their earlier report, that nucleoside levels are not age-dependent and are unaffected by smoking in this group

Topics

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Insulator, Chest X-Ray, Parenchyma, Pleura, Carcinogenic.

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