The epithelium of the hamster trachea in organ culture undergoes hyperplasia and squamous metaplasia after exposure to the amphibole types of asbestos, crocidolite and amosite. These changes are inhibited when the synthetic vitamin A analog, retinyl methyl ether, is incorporated into the culture medium. These findings suggest a possible use for retinoids in the prevention and treatment of respi...

Exposure to asbestos fibers increases the risk of mesothelioma in humans. One hypothetical carcinogenic mechanism is that asbestos fibers may directly induce mutations in mesothelial cells. Although the uptake of asbestos fibers by mesothelial cells is recognized, methods for the quantification of the uptake have not been well established. In the present study, we evaluated two distinct methods...

Asbestos has been described as a physical carcinogen in that its carcinogenic effects appear to be related primarily to fiber dimensions. It has been hypothesized that long asbestos fibers may interfere with chromosome distribution during cell division, causing genomic changes that lead to cell transformation and neoplastic progression. Using high-resolution time-lapse light microscopy and seri...

Asbestos exhibits many properties of classical tumor pro moters. These characteristics include the ability to stimulate proliferation and inhibit normal differentiation of cells. In organ cultures of trachea, crocidolite and amosite asbestos stimulate squamous metaplasia, a pathological process in which a rapidly proliferating squamous epithelium replaces the normal epithe lium. We hypothesized...

The efficiency of the light microscope with that of the electron microscope in detecting asbestos fibres in human lung tissue was computed. Necropsy material from 55 patients who had died from asbestos related diseases was analysed independently by phase contrast microscopy and electron microscopy. As expected the number of fibres identified using electron microscopy was higher than that identi...

Asbestos fibres have been shown to stimulate the mitogen-activated protein kinase signalling cascade in rat pleural mesothelial (RPM) cells after autophosphorylation of the epidermal growth factor receptor (EGFR). We examined if mineral fibres with known carcinogenicity can be discriminated from materials with less or no carcinogenicity by their ability to up-regulate expression of EGFR protein...

It is well known that persons exposed to asbestos display systemic immunological alterations: impaired lymphocyte response to PHA, the appearance of autoantibodies and elevation of the serum immunoglobulin level. The authors intend in this report to determine whether asbestos fibres (crocidolite, chrysotile and amosite) have any effect on the cell cycle of human lymphocytes after PHA stimulatio...

Mesothelial cells, the progenitor cell of the asbestos-induced tumor mesothelioma, are particularly sensitive to the toxic effects of asbestos, although the molecular mechanisms by which asbestos induces injury in mesothelial cells are not known. We asked whether asbestos induced apoptosis in mesothelial cells and whether reactive oxygen species were important. Pleural mesothelial cells (rabbit...