Biologic Markers in Pulmonary Toxicology (1989) / Chapter Skim
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4 Markers of Altered Structure or Function
4 Markers of Altered Structure or Function
Pages 83-90
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From page 83... ...
The cells of the airways are relatively accessible with bronchoscopy, brushing, and biopsy and therefore have great potential as markers of exposure · anc injury. In studying a nasal, tracheal, or bronchial biopsy, it is necessary to establish normal values and appearances of such entities as ciliary beat frequency, cell size, physiologic ion concentration, and structural features as determined by
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From page 84... ...
The tracheobronchial lining consists of a pseudostratified epithelium that contains a diverse population of cell types. The ciliated cell is one of the major cell types and is probably a nonproliferative, terminally differentiated cell.
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From page 85... ...
PARENCHYMA It is in the alveoli that toxic particles and gases exert a fibrogenic influence on the lung interstitial cells that produce connective tissue. The basic cellular and biochemical mechanisms through which inhaled materials cause lung fibrosis are not well established, and it is difficult to ascribe the function of markers to a poorly understood pathologic process.
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From page 86... ...
Morphometric studies of the effects of toxic substances on terminal bronchioles and adjacent alveoli have been few, because of the difficulties involved in dealing with samples from specific regions. The appearance of a few studies in recent years directed at the terminal bronchioles or the proximal alveoli indicates increasing awareness of this site of toxic injury and the development of the necessary morphometric techniques (Barry and Crapo, 1985; Chang et al., 1988~.
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From page 87... ...
Pathologic markers or structural alterations that occur in the pulmonary vessels are usually associated with the development of chronic pulmonary hypertension-e."., intimal hyperplasia, extension of muscle into smaller and more peripheral arteries than normal, increase in medial thickness of normally muscular arteries, reduction in peripheral arterial volume (seen either as a reduction in number of arteries or as a narrowing of intra-acinar arterial luminal diameter) , recanalization of blocked arteries, fibrinoid necrosis, dilatation, and plexiform lesions (Wagenvoort and Wagenvoort, 1977; Harris and Heath, 1986~.
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From page 88... ...
are found in patients with an increase in only pulmonary blood flow; Grade B changes (Grade A changes plus increased medial thickness) , when both pulmonary arterial pressure and blood flow are increased; and Grade C changes (Grade B changes plus reduction in peripheral arterial volume)
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From page 89... ...
Electron Microscopic Examination of Pulmonary Arteries Electron microscopy shows the major cell types in the walls of the pulmonary circulation to be endothelial cells, smooth muscle cells and their precursors and fibroblasts. In experimental models of chronic pulmonary hypertension, such as the rats exposed to hypoxia (Meyrick and Reid, 1978, 1 979b)
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From page 90... ...
Ultrastructural studies also show that smooth muscle cell hypertrophy and alterations in connective tissue synthesis and accumulation contribute to the increased medial thickness seen in preacinar arteries (Meyrick and Reid, 1980~. Future Directions Few reports have suggested alterations in bloodborne mediators in patients with chronic pulmonary hypertension although Geggel and associates have suggested that measurements are possible.
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