Growth Factors And Cognate Receptors For Mesothelioma
One interesting study is called, Characterization of Platelet-derived Growth Factor
and Platelet-derived Growth Factor Receptor Expression in Asbestos-induced Rat Mesothelioma - Cancer Res January 15, 1992 52; 301 by Cheryl Walker, Edilberto Bermudez, Wendy Stewart, James Bonner, Christopher J. Molloy, and Jeffrey Everitt. Here is an excerpt: Abstract - Although altered expression of platelet-derived growth factor (PDGF) is a hallmark of human mesothelioma, expression of PDGF receptors has not been characterized in this cell type. In addition, the expression of this growth factor and its cognate receptor in rodent mesothelioma has not been investigated. In this study, examination of transformed mesothelial cells derived from asbestos-induced rat mesotheliomas revealed that these cells expressed high affinity PDGF receptors (Kd = 0.5 nm) and receptor number was 1.6 105/cell. Western analysis using antibodies specific for either the -type or -type PDGF receptor and Northern analysis using probes specific for - and -type receptor RNA transcripts indicated that these cells expressed -type PDGF receptors but that -type receptors could not be detected. However, when the mesothelioma-derived cells were examined for the expression of PDGF, no expression of this growth factor could be detected. The transformed cells expressed no detectable A- or B-chain PDGF RNA transcripts; and using a competitive enzyme immunoassay specific for isoforms containing the B chain of PDGF and a sandwich enzyme-linked immunosorbent assay specific for A-chain-containing isoforms, neither AA, nor AB, nor BB isoforms of this growth factor could be detected in medium conditioned by these cells. The absence of alterations in PDGF expression in rat mesothelioma, in contrast to the data for the human disease, suggests that the production of this growth factor by transformed mesothelial cells may be species specific.
Another interesting study is called, Leaching of Constituents of Chrysotile Asbestos in vivo - Nature 215, 441 - 442 (22 July 1967); by A. Holmes & A. Morgan - Health Physics and Medical Division, Atomic Energy Research Establishment, Harwell, Didcot, Berkshire. Here is an excerpt: IN recent years, Wagner1 and Selikoff et al. 2 have shown that a rare tumour, the diffuse mesothelioma of the pleura and peritoneum, is associated with past exposure to asbestos. It appears that the amount of asbestos required to produce these tumours is small and that the latent period is very long. The connexion between exposure to asbestos and the production of mesotheliomas is being studied in a number of laboratories, and the possibility that trace metal constituents or contaminating oils may have a role has been suggested3. As yet, little is known about the fate of inhaled asbestos fibres and in particular about their movement out of the lung into other organs. The experiment described here was planned to assess the possibility of using radioactivity, induced in asbestos fibres by neutron irradiation, to trace their translocation in rats after administration by intrapleural injection.
Another study is called, Ferruginous bodies in sputa of former asbestos workers. By Farley ML, Greenberg SD, Shuford EH Jr, Hurst GA, Spivey CG, Christianson CS - Acta Cytol. 1977 Sep-Oct; 21(5):693-700. Here is an excerpt: Abstract - Routine cytopathologic examinations were performed at six-month intervals on sputum specimens from 628 former asbestos workers and 138 control patients. The occurrence of ferruginous bodies in sputa is found to increase as a logarithmic function of the length of occupational exposure to asbestos in workdays. No significant association is found between the occurrence of ferruginous bodies and the worker's age, smoking history, degree of cellular epithelial atypia, or time since last exposure. We conclude that the presence of ferruginous bodies in sputa is evidence of probable significant occupational exposure to asbestos dust. Their absence does not indicate lack of exposure. We can also conclude that routine cytopathology procedures are sufficient for the detection of ferruginous bodies in sputa.
If you found any of these excerpts interesting, please read the studies in their entirety. We all owe a debt of gratitude to these fine researchers.
by: Mont Wrobleski
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