Histological changes are shown of ossification induced by a simultaneous exposure to zinc and cadmium or to zinc and copper using embryonic chick femur in a culture system. Cadmium caused an atrophic change of the osseous tissue in the absence of zinc but caused an osteomalacic change with a partial degenerative change in the presence of zinc after a 6-day culture. Copper caused an atrophic change in the absence or presence of zinc. These observations were partly supported by the fact that the diaphysial calcium content was significantly decreased by zinc alone, and the decrease was unaffected by cadmium or copper. Zinc significantly decreased cadmium accumulation but not copper accumulation in the diaphysis. Thus, in spite of the inhibitory effect on calcification, zinc prevented a decrease in bone matrix formation caused by cadmium but not that by copper. Exposure of chick femur culture to zinc and cadmium induced changes consistent with osteomalacia, i.e., decreased mineralization of bone, with or without suppression of matrix formation. Exposure to zinc and copper, however, induced changes consistent with osteoporosis, i.e., decreased mineralization and matrix formation.

Animals↗

PubMedDate not supplied

Asbestos fiber analysis in seven asbestosis cases.

Asbestos bodies and fibers deposited in the lungs of seven asbestosis cases were counted after tissue digestion. The types and sizes of 100 asbestos fibers for each case were also analyzed. Asbestos bodies were counted with an optical microscope at 100x magnification, and asbestos fibers were counted with a transmission electron microscope (TEM) at 2000x magnification. Most asbestos fibers detected with TEM were longer than 3 microns (92.5%) and thicker than 0.1 microns (92.3%). Short fibers less than 2 microns--both chrysotile and amphiboles, as well as long, thin fibers less than 0.06 microns--would be missed at 2000x (TEM). An average of 1.37 (0.081-5.5) x 10(6) asbestos bodies and 164.8 (0.55-610) x 10(6) asbestos fibers per 5 g wet (0.88 g dry) lung tissue were found, and these values are higher than what was reported in mesothelioma cases without asbestosis that were reported previously. More than 13 (average = 266.2) asbestos bodies were found in a 4-micron-thick tissue section (average area = 3.24 cm2). One asbestos body in a section equaled approximately 5,000 per 5 g wet lung tissue. The intensity of fibrosis was minimal in one case, mild in four, moderate and severe in one each, and the intensity was correlated with the number of asbestos bodies and fibers. The fibrosis in the severe case may have been intensified by repeated infection. Crocidolite fibers were found most frequently (84.7%), were thin, and had a high aspect ratio by our counting rules. Crocidolite with a high aspect ratio may be most fibrogenic in the lung.

Adult↗

PubMedDate not supplied

Asbestos fiber analysis in nine lung cancer cases with high asbestos exposure.

We examined the types and sizes of 100 asbestos fibers in lung tissue obtained from 9 lung-cancer cases (5 autopsy and 4 surgical) with more than 10(4) asbestos bodies per 5 g of wet lung tissue, asbestos bodies in histological sections, and the history of occupational asbestos exposure. Evaluation of asbestos fibers by transmission electron microscopy (2,000 x magnification) revealed that most fibers were longer than 3 microns (96%) and were thicker than 0.1 micron (93%). The analytical conditions we used enabled us to identify 99.7% of all asbestos fibers as being amphibole asbestos. Crocidolite fiber, which was found most frequently (73.1%), was the predominant type of fiber found in 8 of the 9 cases; crocidolite was followed by amosite (21.7%), which was the predominant type found in the remaining case. Crocidolite fibers were thin and had a high aspect ratio (mean diameter = 0.23 micron, mean aspect ratio [length/diameter] = 85.5). Amosite fibers were long, and they also had a high aspect ratio (mean length = 21.8 microns, mean aspect ratio = 66.4). It has been suggested that such fibers with a high aspect ratio are strongly carcinogenic to pulmonary parenchyma. Review of our previous and present data with respect to the ratio of amosite to crocidolite fibers in groups of subjects who had various diseases revealed that this ratio was relatively constant in some occupations. The more predominant fibers found were crocidolite in insulation workers and amosite in railroad workers. The ratio of amosite to crocidolite fibers should be considered in tissue-burden studies.

Adult↗