An ultrastructural morphometric analysis of bronchial secretory cells was carried out on hamsters treated intratracheally with 300 micrograms of human neutrophil elastase (HNE) in 0.5 ml saline, saline alone, or left untreated. Five to 6 animals were killed at 2 h and at 3, 8, and 16 days after treatment. Electron micrographs were prepared from the hilar region of the left main intrapulmonary airway; 125 +/- 16 (mean +/- SE) granulated secretory cells extending from basement membrane to lumen were analyzed for each group. The number (Ng) and area (Ag) of granular profiles per cell, the area of cell profiles (Ac), and the volume density of secretory granules per cell (Vv) were determined using an electronic image analyzer. There were significant decreases in Ng, mean Ag, and Vv in the 2-h HNE group when compared with the saline group. Values of Ng, mean Ag, and Vv were similar for HNE and saline groups at 3 days, but were significantly increased at 8 and 16 days. The Ac of HNE-treated groups was similar to their saline control groups at all time points except at 16 days when the HNE-treated group enlarged to double that of its saline control group. An ultrastructural differential cell count showed a decrease in frequency of granulated secretory cells at 2 h and an increase at 8 and 16 days; there was an inverse change in the frequency of nongranulated secretory cells at these times. The proportion of ciliated, preciliated, and indeterminate cells remained constant over time in all treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)
A single endotracheal instillation of elastase initiates a series of changes in animal lungs that results in a condition resembling human panlobular emphysema. An ultrastructural examination of this series of changes was conducted on the lungs of male golden hamsters exposed to 3H-methylated pancreatic elastase and sacrificed at intervals between 4 hour and 24 days after exposure to enzyme. Lung tissue between 4 and 48 hours showed evidence of hemorrhage and progressive degradation of elastic fibers. Very little indication of epithelial cell damage accompanied these changes. Four days after exposure to elastase, synthesis of new elastic fibers began with the appearance of small clumps of microfibrils in close association with interstitial cells, fibroblasts, and smooth muscle cells. There was also evidence of alterations in alveolar type II cells at this time. Small fibrillar elastic fibers continued to be present in the lung through twenty-four days and may represent a slow repair process or may indicate a structural difference in elastic fibers synthesized after exposure to elastase. Evidence of the continued degradation of elastic fiber could be found up to 16 days after exposure to elastase, revealing that repair processes were occurring in some areas of the lung while destructive process still predominated in other areas.
Plants of Brassica napus were assessed quantitatively for their susceptibility to lateral root crack colonization by Azorhizobium caulinodans ORS571(pXLGD4) (a rhizobial strain carrying the lacZ reporter gene) and for the concentration of glucosinolates in their roots by high-pressure liquid chromatography (HPLC). High-and low-glucosinolate-seed (HGS and LGS) varieties exhibited a relatively low and high percentage of colonized lateral roots, respectively. HPLC showed that roots of HGS plants contained a higher concentration of glucosinolates than roots of LGS plants. One LGS variety showing fewer colonized lateral roots than other LGS varieties contained a higher concentration of glucosinolates than other LGS plants. Inoculated HGS plants treated with the flavonoid naringenin showed significantly more colonization than untreated HGS plants. This increase was not mediated by a naringenin-induced lowering of the glucosinolate content of HGS plant roots, nor did naringenin induce bacterial resistance to glucosinolates or increase the growth of bacteria. The erucic acid content of seed did not appear to influence colonization by azorhizobia. Frequently, leaf assays are used to study glucosinolates and plant defense; this study provides data on glucosinolates and bacterial colonization in roots and describes a bacterial reporter gene assay tailored easily to the study of ecologically important phytochemicals that influence bacterial colonization. These data also form a basis for future assessments of the benefits to oilseed rape plants of interaction with plant growth-promoting bacteria, especially diazotrophic bacteria potentially able to extend the benefits of nitrogen fixation to nonlegumes.
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