Effect of aggregating agents on the electrophoretic mobility of human platelets.

Exposure to Asbestos-Hourihane et al. been shown not to be peritoneal mesotheliomata, since the clinical course and macroscopic appearances of these neoplasms can be very similar (Hourihane, 1964). While necropsy and radiological surveys of other populations would be of great interest, and while the hazards of asbestos exposure are in need of more detailed analyses, the preventive and legal aspects of industrial, domestic, and environmental exposure require urgent consideration. Once pleural plaques have developed the dangers of supervening malignancy are great and the possibility of successful treatment is remote. Summary A close association between exposure to asbestos and the development of pleural plaques has been shown. A cause-and-effect relationship is probable. The most extensive lesions are radiologically detectable, and the disease asbestosis is then also present, despite the absence of any other radiological abnormality. The sources of asbestos are considered and evidence is presented to suggest that there is a widespread non-industrial community exposure. Mesotheliomata are common in patients with pleural plaques, and it is suggested that there is a dose-response relationship between the asbestos and the development of these neoplasms. The question of a relationship between lung cancer and asbestos is left open, but the value of radiological surveys for pleural plaques is emphasized in any study of this problem. Asbestos is not the sole cause of pleural plaques, but it is certainly the most common. We should like to thank the physicians and surgeons of the London Hospital who allowed us to refer to cases under their care, and the registrars of the x-ray department who helped us to collect the radiological series. We are grateful to Professor I. Doniach, Dr. N. Lloyd-Rusby; and Dr. L. J. Rae for encouragement and assistance. We are indebted to Mr. Moss and the film store for their help in tracing a large number of films, to Miss R. L. Cresswell for secretarial assistance, and to the photographic department for the illustrations. In the presence of very low concentrations of adenosine diphosphate (A.D.P.), adenosine triphosphate (A.T.P.), 5-hydroxytryptamine (5-HT), and the adrenalines (Gaarder et al., 1961 ; Mitchell and Sharp, 1964) platelets in a citrated plasma system adhere together to form aggregates, but the mechanism of this type of aggregation is unknown. Platelets carry a negative surface charge (Abramson, 1928), and they would normally be expected to repel each other; during aggregation the electrostatic forces must be overcome. The surface charge on cells …