Documents lung biopsy 4 results

Background: The health effects of asbestos are intimately related to the fate of inhaled fibers in the lungs. The kinetics of asbestos fibers have been studied primarily in rodents. The objective of this study was to explore the application of these kinetic models to human autopsy data. Methods: We analyzed the asbestos fiber content of the lungs of 72 Quebec chrysotile miners and millers and 49 control subjects using analytical transmission electron microscopy. Statistical methods included standard multivariate linear regression and locally weighted regression methods. Results: The lung burdens of asbestos bodies and chrysotile and tremolite fibers were correlated, as were the concentrations of short, medium, and long fibers of each asbestos variety. There were significant associations between the duration of occupational exposure and the burdens of chrysotile and tremolite. The concentration of chrysotile decreased with the time since last exposure but the concentration of tremolite did not. The clearance rate varied inversely with the length of chrysotile fibers. For fibers greater than 10 in length the clearance half-time was estimated to be 8 years. Conclusions: The patterns in our data are compatible with both of the hypotheses suggested from rodent experiments; the existence of a long-term sequestration compartment and overload of clearance mechanisms in this compartment.

"For diagnostic purposes, mineralogical analysis was performed in bronchoalveolar lavage fluid and lung tissue from a 58-year-old patient previously exposed to asbestos and rare earth dusts. No significant retention of asbestos was demonstrated in lung tissue by light microscopy (asbestos bodies) or transmission electron microscopy analysis (uncoated fibers). Particles containing rare earth (cerium, lanthanum) and phosphorus were identified in alveolar macrophages in bronchoalveolar lavage fluid, and cerium-containing particles accounted for 70% of particles observed in the lung tissue. Ultrastructural analysis of lung tissue revealed the presence of particles containing cerium and phosphorus in interstitial macrophages and elastic fibers. These results suggest that rare earth is metabolized and should be considered as biopersistent in the human respiratory tract, since occupational inquiries revealed that exposure to cerium oxide abrasive powder had ceased at least 15 years earlier."

"Nanoparticles are being used in ever increasing numbers in a range of industrial and medical products. Questions surrounding their potential to cause toxic effects in humans have been raised. Although animal experiments predict that nanoparticles are more toxic than their larger counterparts there are few descriptions in the literature of human exposure. A case described in 1994 has been re-examined from a pathology perspective. The subject, a 38-year-old previously healthy male, inhaled nanoparticles of nickel while spraying nickel onto bushes for turbine bearings using a metal arc process. He died 13 days after being exposed and the cause of death at autopsy was adult respiratory distress syndrome (ARDS). Nickel particles <25nm in diameter were identified in lung macrophages using transmission electron microscopy. High levels of nickel were measured in his urine and his kidneys showed evidence of acute tubular necrosis."