Double-stranded RNA regulation of DNA synthesis in fibroblasts

The double-stranded RNA molecule polyinosinic-polycytidylic acid (poly IC) has been found in some studies to have a mitogenic effect on fibroblast proliferation while other studies found poly IC to have an inhibitory effect on proliferation. In this study, we investigated whether a stabilized form of poly IC complexed with poly-L-lysine and carboxymethylcellulose (poly ICLC) had a bidirectional effect on DNA synthesis in fibroblasts from four different cell lines and determined factors that potentially influence this bidirectional effect. In medium containing fetal bovine serum, poly ICLC slightly increased the levels of [3H]thymidine incorporation in growing fibroblasts in three of the four fibroblast cell lines tested, while poly ICLC increased [3H]thymidine incorporation in confluent, quiescent fibroblasts in two of four cell lines. Poly ICLC did not induce DNA synthesis in subconfluent, quiescent or in confluent, quiescent fibroblasts under serum-free conditions. Poly ICLC significantly suppressed serum-induced [3H]thymidine incorporation by quiescent fibroblasts in all cell lines. We conclude that the stimulatory and inhibitory effects of poly ICLC on DNA synthesis are influenced by both the cell line and the presence of serum components in the culture medium but not by population density.

Pulmonary inflammation and epithelial injury in response to acute ozone exposure in the rat

To document the time course of the inflammatory response and epithelial injury in the lung following an acute ozone exposure, rats were exposed to 1.0 ppm ozone for periods between 4 and 24 hr. Some of the exposures were followed by postexposure periods in filtered air for up to 20 hr. Bronchoalveolar lavage fluid (BALF) analysis and electron microscopic morphometry on centriacinar regions of lungs fixed by intravascular perfusion were used to assess the degree of pulmonary inflammation and epithelial cell necrosis. Total protein and numbers of neutrophils and epithelial cells in BALF increased as the duration of ozone exposure increased, while BALF macrophages decreased. Quantitation of the neutrophil response in centriacinar lung regions (capillary, interstitial, and epithelial/luminal compartments of the terminal bronchiole and proximal alveolar duct) by morphometry generally correlated with the BALF analysis, and revealed a greater volume per surface area epithelial basal lamina (Vs) of neutrophils in the terminal bronchiole compartments compared to proximal alveoli. Necrosis of epithelial cells in terminal bronchioles, primarily ciliated cells, occurred as early as 4 hr after initiation of ozone exposure, before marked neutrophil migration, and continued during periods of maximal neutrophil influx. We concluded that the early epithelial necrosis in terminal bronchioles during the first few hours of ozone exposure was primarily due to direct ozone toxicity, but could not rule out the possibility of neutrophils contributing to the injury at later time points, especially between 8 and 12 hr of exposure (during periods of maximal neutrophil migration).

Repeated exposures to enzyme-generated oxidants cause alveolitis, epithelial hyperplasia, and fibrosis in hamsters

Oxidant-mediated epithelial injury and repair processes may promote the development of pulmonary fibrosis. The authors examined this hypothesis by inducing oxidant injury in hamsters with intratracheally instilled mixtures of glucose, glucose oxidase (GO) and lactoperoxidase at weekly intervals. Solutions containing denatured GO (DE) served as a control treatment. One and six days after each treatment, anesthetized animals were sacrificed and lavaged, and their lungs and plasma were preserved for further study. Although DE-treatment consistently evoked a transient, neutrophil-rich inflammatory response, no significant biochemical or morphologic changes were detected at the ensuing 6-day time points. In contrast, repeated GO treatments prolonged inflammation and injured the alveolar epithelium, evidenced by significantly greater levels of neutrophils and macrophages in bronchoalveolar lavage fluid (BALF) and increased BALF levels of protein, beta-glucuronidase and lactic dehydrogenase activities. Active GO also altered BALF lymphocytes and monocytes, but no discernable pattern emerged. Fibrotic, consolidated parenchyma appeared after the second and third GO exposures, coinciding with increased levels of total collagen, prolyl hydroxylase activity, and anti-oxidant enzyme activities. Although alveolitis and type II cell hyperplasia were observed after the initial treatment, polyplike nodules covered by hyperplastic, undifferentiated epithelium were evident after the third treatment. After each exposure, GO-treated animals had larger volumes of parenchymal lesion than DE-treated hamsters. These data indicate that normal alveolar epithelial repair processes were greatly disrupted by repeated oxidant injury and suggest that repeated and/or continued epithelial injury may contribute to the development of pulmonary fibrosis.

Morphometric assessment of pulmonary toxicity in the rodent lung

An overview of the epithelial and interstitial composition of rat respiratory airways shows complexity and variability. Airway epithelium varies in 1) different airway levels; 2) the types and ultrastructure of cells present; and 3) the abundance, type, and composition of stored secretory product. Unbiased sampling of airways is done using airway microdissection with a specific binary numbering system for airway generation. Vertical sections of selected airways are used to sample epithelium and interstitium. We determine the ratios of the volume of epithelial or interstitial cells to the total epithelial or interstitial volume (Vv). The surface of the epithelial basal lamina to the total epithelial or interstitial volume (Sv) is determined using point and intersection counting with a cycloid grid. Using the selector method on serial plastic sections, we determine the number of epithelial or interstitial cells per volume (Nv) of total epithelium or interstitium. We calculate the number of epithelial or interstitial cells per surface of epithelial basal lamina (Ns) by dividing Nv by Sv where the volumes are the same compartment. We calculate average cell volumes (v) for specific epithelial and interstitial cells by dividing the absolute nuclear volume by the ratio of the nucleus to cell volume (Vv). By multiplying the average cell volume (v) by the ratio of organellar volume to cell volume (Vv), we calculate the average organellar volume per cell. These unbiased stereological approaches are critical in a quantitative evaluation of toxicological injury of rat tracheobronchial airways.

Amelioration of bleomycin-induced pulmonary fibrosis in hamsters by combined treatment with taurine and niacin

Interstitial pulmonary fibrosis induced by bleomycin (BL) involves the production of reactive oxygen species and the impairment of repair of damaged epithelial cells. We have shown previously that taurine or niacin treatment partially attenuates BL-induced lung fibrosis in hamsters and that the two agents probably act through different mechanisms. In the present investigation, we have demonstrated that taurine and niacin in combination provide nearly complete protection against BL-induced pulmonary fibrosis. Based on the findings of this investigation, it is suggested that combined treatment with taurine and niacin offers the potential for a novel pharmacological approach in the prevention of lung fibrosis in humans.

A morphometric study of the lungs of different sized bats: correlations between structure and function of the chiropteran lung

1. The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL, 456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric methods. These data increase fivefold the range of body masses for which bat lung data are available, and allow more representative allometric equations to be formulated for bats. 2. Lung volume ranged from 4.9 cm3 for PH to 39 cm3 for PP. The volume density of the lung parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94% in PP to 89% in PH. Of the components of the parenchyma, the alveoli composed 89% and the blood capillaries about 5%. 3. The surface area of the alveoli exceeded that of the blood-gas (tissue) barrier and that of the capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 microns) and PP had the thickest (0.3033 microns). 4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange performance of its lungs. 5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these pulmonary structural disparities in different species of bats must await additional physiological and flight biomechanical studies. 6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data (b = 0.82) exceeds the value for flight VO2max (b = 0.70), those for the surface area of the blood-gas (tissue) barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung diffusing capacity for oxygen (b = 0.69) all correspond closely to the VO2max value. 7. Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying mammals reveal that superiority of the bat lung over that of the non-flying mammal.(ABSTRACT TRUNCATED AT 400 WORDS)

Repeated episodes of C5a-induced neutrophil influx do not result in pulmonary fibrosis

Multiple reactive oxygen species-induced epithelial injury by glucose, glucose oxidase, and lactoperoxidase instillation in the lung results in a progressive interstitial fibrosis. To test the hypothesis that multiple pulmonary inflammatory responses alone would not result in fibrosis, three sequential inflammatory reactions were produced at weekly intervals in hamster lungs via intratracheal instillation of human recombinant C5a. Numbers of neutrophils and total inflammatory cells in bronchoalveolar lavage (BALF) increased significantly at 24 h after each C5a treatment compared with saline controls. Neutrophils increased by 3-, 33-, and 34-fold compared with the corresponding controls at 24 h after the first, second, and third doses, respectively, but returned to control levels by six days postinstillation. LTB4 levels increased by 24% and 20% compared with the corresponding controls at 24 h after the first and second doses but were not different from controls at other times. Hydroxyproline levels in treated animals did not differ significantly from control levels throughout the study. Protein levels were significantly increased at 24 h after the second and third doses and six days after the third dose compared with the corresponding controls. Occasional foci of neutrophils in alveolar spaces were observed at 24 h after each dose, but they decreased in frequency after six days. No foci of neutrophils were observed six days after the final dose, although some epithelial degeneration was observed by transmission electron microscopy. Our results indicate that pulmonary inflammation resulting from repeated influx of neutrophils in response to multiple instillations of C5a in the lung does not cause sufficient injury to result in pulmonary fibrosis.

Epithelial injury, inflammation, and repair in the hamster lung following intratracheal instillation of enzyme-generated oxidants

Oxidant-induced inflammatory and morphologic changes evoked by intratracheally instilled glucose, active glucose oxidase, and lactoperoxidase in hamsters are described. Similar solutions containing heat-denatured (DE) glucose oxidase served as a control treatment. During the 7-week post-treatment period, animals were sacrificed and lavaged, and their lungs were preserved for later study. Although a neutrophil-rich alveolitis was observed initially in both groups, the leukocytic influx and mild morphologic changes in DE-treated animals resolved within 7 days. In contrast, glucose oxidase mixtures caused necrotic alveolar epithelium, fibrin-like exudate, and significantly higher neutrophil and protein levels in bronchoalveolar lavage fluid (BALF) after 1 day. At 4 days, type II cell hyperplasia was extensive and BALF levels of all inflammatory cell types were significantly greater than BALF counts in DE animals. By 7 days, BALF macrophage and lymphocyte levels remained significantly elevated, and epithelial hyperplasia coincided with marked increases in lung hydroxyproline and interstitial cells. BALF parameters suggested that inflammation induced by glucose oxidase resolved within 15 days, yet total hydroxyproline levels remained elevated at 15 days and epithelial lesions were still detectable at 29 days. Oxidant-induced inflammation and epithelial injury were transient and preceded moderate collagen deposition.

A comparison of terminal airway remodeling in chronic daily versus episodic ozone exposure

This study compares centriacinar changes by ultrastructural morphology and morphometry following daily versus episodic ozone exposure in rats. Three groups of rats were exposed to air, 0.95 ppm ozone 8 hr daily for 90 days, and 0.95 ppm ozone 8 hr daily in seven successive 5-day episodes separated by 9-day recovery periods for a total of 89 days. Sections from the left lung and dissected acini from the right middle lobe were studied by light and electron microscopy. The centriacinar lesion following episodic exposure was similar but diminished in severity compared to that of rats exposed daily. Damage following episodic exposure appeared to be more than predicted by an exposure regimen which delivered 35% of the total ozone dose during daily exposure. The total volume of affected parenchyma was similar following both exposures. Respiratory bronchiole formation increased following both exposures but this was only statistically significant following daily exposure. The most severe epithelial damage was at the tips of alveolar septa in alveolar ducts distal to the respiratory bronchiole. Interstitial thickness in the injured respiratory bronchiole and proximal alveolar duct increased significantly and similarly following both exposures. Epithelium along the respiratory bronchiole of daily exposed rats was more differentiated. In the episodic group, respiratory bronchiole and alveolar duct epithelium consisted of a range of intermediate, less differentiated bronchiolar or alveolar epithelial cells. The episodic exposure resulted in a diminished lesion, but there appears to be some cumulative effect of repeated exposures with respiratory bronchiolar and alveolar duct epithelium in a more dynamic state of injury and repair.

Correlation of sensory electroneurographic recordings and myelinated fiber diameters of the superficial peroneal nerve of dogs

The compound nerve action potential (CNAP) of the superficial peroneal nerve of dogs was investigated to determine: (1) the influence of the stimulation technique on the configuration of the CNAP, with particular attention to late components; (2) the fiber diameter (FD) distribution; and (3) the relationship between FD distribution and CNAP configuration, by reconstruction of CNAP made on the basis of FD distributions. The CNAP were evoked in 9 dogs under halothane anesthesia by 2 stimulation methods: percutaneous needle electrode stimulation and direct stimulation of the exposed superficial peroneal nerve. Recordings were made with percutaneous needle electrodes. Full nerve cross sections of 7 superficial peroneal nerves were prepared for FD morphometric analysis. Reconstruction of CNAP were made on the basis of the FD distributions. Late components of the CNAP could be evoked with either stimulation method, but only with a stimulus intensity of 3 to 5 times maximal for the main (early) component of the CNAP. The FD histograms of 7 analyzed nerves had bimodal distribution. In 5 nerves, peaks were at 4.2 to 4.5 microns and 9.0 to 10.0 microns, with 60% of the fibers in the small-diameter group. In 2 nerves with lower maximal conduction velocities, peaks were shifted toward smaller values. The CNAP reconstructions made by use of FD data closely resembled actual recordings when a fifth-order polynomial function was applied to the relationship between nerve conduction velocity and FD. Reconstructions made by use of 1 or 2 linear functions did not accurately resemble actual recordings.(ABSTRACT TRUNCATED AT 250 WORDS)

Polyinosinic-polycytidylic acid, an interferon inducer, ameliorates bleomycin-induced lung fibrosis in mice

The inhibitory effect of polyinosinic-polycytidylic acid (Poly IC), an inducer of interferons, on bleomycin-induced lung collagen accumulation was investigated in mice. Poly IC (10 mg/kg, intraperitoneally) or saline was given for 2 days and immediately prior to intratracheal instillation of bleomycin (0.125 units/mouse) or an equivalent volume of saline and thereafter daily for 13 days. Lung hydroxyproline levels in saline-saline (control), Poly IC-saline (Poly IC), bleomycin-saline and bleomycin-Poly IC groups averaged 279, 287, 459, and 358 micrograms/lung, respectively. The bleomycin + Poly IC mice had significantly less lung hydroxyproline than bleomycin mice, but significantly more hydroxyproline than control or Poly IC mice. Similarly, bleomycin + Poly IC mice had significantly less protein in bronchoalveolar lavage fluid (BALF) supernatant than bleomycin mice, but significantly more protein than control or Poly IC mice. Total cell counts for cells recovered from BALF showed significant increases of 174 and 167% in bleomycin and bleomycin + Poly IC as compared to controls, while the Poly IC group showed a significant decrease of 47% which was primarily due to a decrease in alveolar macrophages. The bleomycin group had significantly more neutrophils, monocytes, macrophages, and lymphocytes than control mice, while bleomycin + Poly IC mice lacked the significant increase in lymphocytes. Bleomycin + Poly IC mice had significantly more monocytes than the bleomycin group. All bleomycin-treated mice had lung lesions, but no lesions were observed in control or Poly IC mice. Bleomycin + Poly IC mice had significantly more (58%) lesions than bleomycin. In contrast, the volume of interstitial lesion in bleomycin + Poly IC mice showed significantly less extracellular fibers (decreased by 62%) and no difference in fibroblasts as compared to bleomycin mice. Fibrotic lesions in bleomycin mice were multifocal and varied from large areas of organized connective tissue to thickened septa lined by cuboidal epithelial cells. Interstitial lesions in bleomycin + Poly IC had a significantly greater volume of mononuclear phagocytes and lymphocytes, but less organized connective tissue than the bleomycin group. Poly IC treatment ameliorated bleomycin-induced lung collagen accumulation.

Eosinophils cause acute edematous injury in isolated perfused rat lungs

Eosinophils produce oxidants and other toxic substances and thus have the potential to cause acute lung injury. We found that addition of normal human eosinophils and the respiratory burst stimulant phorbol myristate acetate to isolated perfused rat lungs acute edematous injury as reflected in weight gain and morphologic changes. Lung to body weight ratio (x 10(3) was 16.7 +/- 3.3 in the experimental group with stimulated eosinophils added compared with 4.7 +/- 0.38 for the control group. Morphologic examination showed both epithelial and endothelial damage. This injury was ameliorated by the addition of catalase, which neutralizes hydrogen peroxide produced during the respiratory burst. Lung/body weight ratio in the group with stimulated eosinophils plus catalase was 7.8 +/- 1.1, and the specimens were indistinguishable from control specimens by histopathologic examination. Our results indicate that eosinophils are capable of causing acute lung injury. This injury is mediated, at least in part, by toxic oxygen products.

Dynamics of uptake and channeling of arachidonic acid in hamster alveolar macrophages and the effect of bleomycin on arachidonyl distribution

The uptake and distribution of [14C]-arachidonic acid (AA) by primary culture hamster alveolar macrophages (AM) were examined. The macrophages were incubated for 2 to 18 hrs in RPMI-1640 medium containing 0.1% BSA and [14C]-AA. The uptake of [14C]-AA by AM was rapid with 71% and 83% of exogenous [14C]-AA taken up after 2 and 4 hrs of incubation, respectively. Initially, the uptaken [14C]-AA was equally distributed between phospholipids (PL) and neutral lipids (NL). However, by 8 hrs, 86% and 14% of [14C]-AA was found in PL and NL, respectively. This distribution pattern remained constant through 18 hrs. Within the PL pool, most of the [14C]-AA was initially incorporated into phosphatidylcholine (PC). However, with time, as the percent of [14C]-AA incorporated in PC declined, the percent incorporated in phosphatidylethanolamine increased. The incorporation of [14C]-AA into sphingomyelin, phosphatidylinositol, and phosphatidylserine remained constant with time. Within the NL, most of the [14C)-AA was initially found incorporated into triacylglycerols (TG). After 4 hrs, the percent of [14C]-AA found in TG decreased markedly, while the percent found in cholesterol esters markedly increased. Incubation of AM prelabeled with [14C]-AA with bleomycin at 0.5, 5, 50 and 500 microM for 2 and 8 hrs failed to have any effect on the distribution of [14C]-AA in PL and NL pools.

Effects of three cysteine pro-drugs on bleomycin-induced lung fibrosis in hamsters

The cysteine pro-drug Z2196 ((2RS, 4R)-2-methylthiazolidine carboxylic acid) and two drugs with methyl esters attached to Z2196 (Z2197 and Z2199) were evaluated for antifibrotic effects in the hamster bleomycin model of lung fibrosis. Each drug or phosphate-buffered saline (PBS) was given daily (300 mg/kg intraperitoneally) for 2 days before intratracheal instillation of bleomycin (7.5 units/kg) or saline for an additional 13 days. Lung collagen measured as hydroxyproline was significantly increased to 138% of the control groups in the PBS + Bleomycin treated group, but the Z2196 + Bleomycin group was increased to 108% and was not statistically different from controls. Protein content of bronchoalveolar lavage supernatant in PBS + Bleomycin treated hamsters was significantly increased to 326% of controls. The protein content of bronchoalveolar lavage supernatant for all cysteine pro-drug + Bleomycin treated hamsters was increased to 160% of PBS + Bleomycin treated hamsters. All the Bleomycin treated hamsters had significantly more cells and more neutrophils recovered in bronchoalveolar lavage than controls. The PBS + Bleomycin treated hamsters had significantly more lymphocytes in bronchoalveolar lavage than all the other treatment groups. The Z2196 + Bleomycin and Z2197 + Bleomycin hamsters had significantly less monocytes in BALF than PBS + Bleomycin hamsters. The lung total sulfhydryl and nonprotein sulfhydryl in PBS + Bleomycin treated hamsters were increased to 210% and 253% of controls, respectively, whereas in Z2196 + Bleomycin hamsters they were increased to 152% and 153%, respectively. Histopathology of PBS + Bleomycin hamsters showed a diffuse mixed mononuclear alveolitis, multifocal fibrosis and peribronchiolar fibrosis, whereas Z2196 + Bleomycin hamsters showed notably less alveolitis and fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Niacin attenuates bleomycin-induced lung fibrosis in the hamster

Bleomycin (BLM)-induced lung fibrosis has been shown to be accompanied by the activation of poly(ADP-ribose) polymerase and depletion of nicotinamide adenine dinucleotide (NAD) in the lung. Niacin, a precursor of NAD, was used in the present study to investigate its possible ameliorating effect on BLM-induced pulmonary fibrosis in hamsters. Niacin (500 mg/kg IP) or saline (IP) was injected daily for 16 or 23 days. On day 3, hamsters were treated with BLM (7.5 U/5 mL/kg) or an equivalent volume of saline intratracheally. BLM alone significantly increased lung hydroxyproline levels, bronchoalveolar lavage fluid protein concentration, and various inflammatory cell counts in the lavage in both experiments. In addition, BLM alone elevated prolyl hydroxylase and poly(adenosine-5'-diphosphate [ADP]-ribose) polymerase activities in the 3-week study. Niacin treatment significantly decreased BLM-elevated lung hydroxyproline, prolyl hydroxylase, and poly(ADP-ribose) polymerase activities. Histopathology revealed that niacin treatment attenuated BLM-induced thickened alveolar septa, foci of fibrotic consolidation, and accumulations of inflammatory cells in the parenchyma and air spaces. The ability of niacin to attenuate BLM-induced lung fibrosis in hamsters suggests that it may have potential as an antifibrotic agent in humans.

Cytodifferentiation of two epithelial populations of the respiratory bronchiole during fetal lung development in the rhesus monkey

This study describes the cytodifferentiation of the two populations of epithelial cells found in the respiratory bronchiole of the adult rhesus monkey. One population, pseudostratified and containing ciliated, nonciliated secretory, and basal cells, is found overlying the pulmonary artery (PA). The other population, not associated with the PA, contains nonciliated cuboidal cells between alveolar outpockets. In this study we used terminal conducting airways from the lungs of fetal (90 to 155 days gestational age [DGA]), postnatal, and adult rhesus monkeys. Ciliated cells were partially differentiated at 90 DGA (54% gestation) and completely differentiated by 134 DGA (80% gestation). Nonciliated secretory cells were partially differentiated at 95 DGA (57% gestation) but did not lose all glycogen until the postnatal period. Basal cells appeared by 134 DGA (80% gestation) and matured in the postnatal period. Small mucous granule cells appeared at 125 DGA (74% gestation) and did not change throughout fetal development. Neuroendocrine cells were present throughout the entire period studied. Nonciliated cuboidal bronchiolar cells of the nonciliated population of the respiratory bronchiole appeared at 105 DGA (62% gestation) and matured in the postnatal period. We conclude that 1) although most of the differentiation of the lower airway occurs before birth, most of the cell types are not completely differentiated at birth; 2) the sequence of differentiation for the cells of the ciliated pseudostratified epithelial population is ciliated, nonciliated secretory, and basal; 3) the sequence of differentiation for the nonciliated secretory cell is similar to that of the secretory cells in more proximal airways; and 4) basal, neuroendocrine, and small mucous granule cells are not a part of the differentiation sequence of the other cell types.

Dose-related effects of enzyme-generated oxidants on the biochemistry and morphology of the hamster lung

Reactive oxygen species (ROS) have been closely associated with a number of pathological disorders, including interstitial pulmonary fibrosis. While models of ROS-induced fibrosis offer advantages over chemically-induced fibrosis, the biochemical and morphological features of ROS-induced fibrosis have yet to be extensively documented. In this study, we evaluated the effect of initial ROS dose on lung injury and repair. Male hamsters received a single dose of glucose, glucose oxidase and lactoperoxidase via the intratracheal route. From 3 to 14 days post-treatment, a significant dose-related body weight loss was observed. There was a trend towards greater mortality with increasing dose. After 2 weeks, we noted significant, dose-related increases in lung levels of collagen, lipid peroxidation products, nucleic acids, and protein. Similarly, total lung catalase, lactic dehydrogenase and glutathione reductase activities were also elevated significantly above control values in a dose-related fashion. A concurrent, dose-dependent thickening of alveolar septa in ROS-treated lungs was composed of epithelial hyperplasia, hyperemia, edema and accumulations of interstitial fibers and macrophages. Interstitial and alveolar macrophages in ROS-induced lesions were enlarged and contained numerous primary and secondary lysosomes. These results demonstrate that, in the hamster lung, injury induced by enzyme-generated ROS can initiate dose-dependent fibroproliferative changes which eventuate into interstitial fibrosis.

Hypophysectomy and porcine fetal lung development

The effect of hypophysectomy on the development of the lung parenchyma and maturation of pulmonary alveolar type II cells was examined in the fetal pig. In fetuses from four different gilts, hypophysectomy was performed on gestational day 69 or 70. Littermates from the same gilts served as controls. Fetuses were delivered by caesarean section at term (113 +/- 1 days of gestation), and the lungs were fixed by intratracheal instillation. Plasma cortisol and thyroxine concentrations in the umbilical artery were markedly lower for hypophysectomized fetuses compared with control fetuses. Body weight was similar for both groups of fetuses. Total lung volume was 53% smaller in hypophysectomized fetuses compared with control fetuses. However, alveolar septal tissue and capillary luminal volumes were similar in both groups. Total lung alveolar surface area was twice as great in control animals compared with hypophysectomized animals. The volumes of epithelium, interstitium, and endothelium of centriacinar alveolar septa per unit surface area of epithelial basal lamina were 3.7, 4.8, and 2.4 times greater in hypophysectomized fetuses compared with control fetuses. Alveolar type II cell composition also differed significantly between groups. The volume fraction of glycogen in type II cells was 51% for hypophysectomized fetuses and 12% for control fetuses, while lamellar body volume fraction was 8% in hypophysectomized fetuses and 23% in control fetuses. The frequency of alveolar type II cell contact with mesenchymal interstitial cells via foot processes was 5 times greater in the lungs of control animals compared with hypophysectomized animals. These findings demonstrate significant effects of hypophysectomy on the morphogenetic and cytodifferentiation activities of all major tissue compartments of the pulmonary gas exchange area during the final trimester of fetal development.

Characterization of a phospholipase A2 in hamster lung and in vitro and in vivo effects of bleomycin on this enzyme

Phospholipase A2 (PLA2) activity from adult hamster lung was characterized using L-alpha-1-palmitoyl-2-arachidonyl-[arachidonyl-1-14C]-phosphatidylcholine as the substrate. The released [14C]-arachidonic acid was separated by TLC. The enzyme activity increased with increasing incubation time (0-120 minutes), calcium ion concentration (0-25.0 mM) and protein (0-2.0 mg). The optimum pH was 8.0. Deoxycholate had a concentration dependent (0.1 to 0.5 mM) inhibitory effect on the activity. PLA2 specific activity was the highest in mitochondrial fraction. PLA2 activity following incubation with bleomycin was increased in a dose related fashion. In vivo study showed that both PLA2 activity and collagen content in hamster lung were significantly elevated at 14 days followed intratracheal instillation of bleomycin. The activation of PLA2 may play an important role in bleomycin-induced pulmonary toxicity.

Effects of taurine on bleomycin-induced lung fibrosis in hamsters

Four groups of hamsters were assigned as saline + saline, taurine + saline (TS), saline + bleomycin (SB), and taurine + bleomycin (TB). The animals were treated with either saline or taurine (500 mg/kg ip) for 1 week and just prior to intratracheal instillation of bleomycin (7.5 units/kg) or saline on the eighth day. Thereafter, taurine administration was continued ip (250 mg/kg) and in drinking water (1%) for another 14 days. Bleomycin-induced increases in lung collagen were significantly inhibited in TB hamsters. Plasma taurine concentration in the TS group was significantly higher than that of the other groups. Lung lavage (bronchoalveolar lavage fluid) taurine in the SB group was significantly higher than the saline + saline and TS groups. Bronchoalveolar lavage fluid supernatant protein and acid phosphatase levels in the SB and TB groups were significantly increased over the saline + saline and TS groups. Although the total number of cells recovered in bronchoalveolar lavage fluid was not different among the four groups, there were significantly fewer neutrophils in the TB as compared with SB hamsters. Morphometric analysis revealed less than half as much lesion (diffuse mononuclear alveolitis and multifocal fibroplasia) in TB as compared with SB hamsters. Also, consolidated foci were less frequent and smaller in TB as compared with SB hamsters. Taurine may attenuate bleomycin-induced inflammation and fibrosis by scavenging reactive oxygen metabolites.

Tracheobronchial epithelium in the adult rhesus monkey: a quantitative histochemical and ultrastructural study

Previous studies of the intrapulmonary conducting airways of sheep and rabbit have demonstrated marked diversity in the epithelial populations lining them. Because studies of trachea and centriacinar regions of macaque monkeys suggested that primates may be even more diverse, the present study was designed to characterize the epithelial population throughout the airway tree of one primate species, the rhesus monkey. Trachea and intrapulmonary airways of the right cranial and middle lobes of glutaraldehyde/paraformaldehyde-infused lungs of five adult rhesus monkeys were microdissected following the axial pathway. Each branch was assigned a binary number indicating its specific location within the tree. The trachea and six generations of intrapulmonary airway from the right cranial lobe were evaluated for ultrastructure and quantitative histology as were those of the right middle lobe for quantitative carbohydrate histochemistry. Four cell types were identified throughout the tree: ciliated, mucous goblet, small mucous granule, and basal. The tallest epithelium lined the trachea; the shortest, the respiratory bronchiole. The most cells per unit length of basement membrane were in proximal intrapulmonary bronchi; the least, in the respiratory bronchiole. The nonciliated bronchiolar epithelial or Clara cell was restricted to respiratory bronchioles. Sulfomucins were present in the vast majority of surface goblet cells in the trachea and proximal bronchi. In proximal bronchi, neutral glycoconjugates predominated in glands and acidic glycoconjugates in surface epithelium. In terminal and respiratory bronchioles the ratio of acidic glycoconjugate to neutral glycoconjugate equaled that in proximal bronchi, although glands were not present. Sulfomucins were minimal in terminal airways. We conclude that the characteristics of the epithelial lining of the mammalian tracheobronchial airway tree are very species-specific. The lining of the rhesus monkey does not have the diversity in cell types in different airway generations observed in sheep and rabbit. Also, the populations lining these airways in the rhesus are very different from either the sheep or rabbit in number, proportions of different cell types, glycoconjugate content, and distribution of specific cell types.

Synergistic interaction of ozone and respirable aerosols on rat lungs. IV. Protection by quenchers of reactive oxygen species

In previous studies we have shown interactions between ozone and acidic respirable aerosols as evaluated by sensitive biochemical and quantitative morphological endpoints. In the present paper we have attempted to test the hypothesis that active oxygen species might play a role in lung damage caused by ozone +/- sulfuric acid aerosol. Rats were administered various scavengers of active oxygen species via the intraperitoneal (i.p.) route before and during exposure to 0.12, 0.20, or 0.64 ppm of ozone +/- 0.04, 0.1, 0.2, 0.5, or 1.0 mg/m3 of sulfuric acid aerosol. Vitamin E, a lipid-soluble free radical scavenger, beta-carotene (the precursor of vitamin A), a singlet oxygen scavenger, and dimethylthiourea, a hydrogen peroxide scavenger, were tested. Dimethylthiourea at doses of 50-500 mg/kg per day was able to protect rats from the effects of ozone, suggesting a role for hydrogen peroxide in ozone-induced lung damage in vivo. Neither vitamin E nor beta-carotene at 100 mg/kg doses had any protective activity in our experiments, despite documentation of increased lung content of the scavengers in animals receiving these agents. These results suggest that water solubility may play a role in the efficacy of the scavenging agents under our exposure protocols. We conclude that: (1) hydrogen peroxide may be involved in ozone-induced lung damage; and (2) that lung injury by ozone and by ozone + sulfuric acid aerosol may share common pathways.

Ameliorating effect of an interferon inducer polyinosinic-polycytidylic acid on bleomycin-induced lung fibrosis in hamsters. Morphologic and biochemical evidence

The effects of polyinosinic-polycytidylic acid (Poly I:C), an inducer of interferons, on bleomycin (Bleo)-induced lung fibrosis was studied in hamsters. Poly I:C (10 mg/kg intraperitoneally) was administered for two days and immediately before intratracheal instillation of bleomycin (7.5 U/kg) or an equivalent volume of saline and thereafter daily for 13 days. The lung hydroxyproline in control, Poly I:C, Bleo, and Bleo + Poly I:C groups averaged 791, 752, 1177, and 766 micrograms/lung. As compared to control, the prolyl hydroxylase activity in the Bleo group was increased by 83% whereas in Bleo + Poly I:C group, the activity was increased by 42%. Protein in the bronchoalveolar lavage supernatant in Poly I:C, Bleo and Bleo + Poly I:C groups were 72, 286, and 206% of the control, respectively. There was no difference in total leukocyte counts between Bleo + Poly I:C and Bleo groups, but the differential cell counts were changed. The numbers of neutrophils, monocytes, lymphocytes, and eosinophils were 50, 84, 91, and 10% of Bleo group, respectively. Morphometric estimates of the volume of parenchymal lesion within the lung showed that hamsters in Bleo + Poly I:C group had significantly less volume of lesion (1.0 cucm) than the Bleo group (1.6 cucm). In addition, the fibrotic lesions in Bleo + Poly I:C group were multifocal and primarily proximal acinar in location, had fewer extracellular fibers, neutrophils and monocytes. Poly I:C treatment ameliorated bleomycin-induced lung collagen accumulation.

Effects of intratracheal administration of xanthine plus xanthine oxidase on lung antioxidant enzymes, lipid peroxidation, and collagen in hamsters

Xanthine (X) and xanthine oxidase (XO) were injected intratracheally (IT) in hamsters at Day 0 (38 mg X, 100 micrograms XO) and Day 5 (38 mg X, 250 micrograms XO). Control hamsters received saline or X (38 mg) plus boiled XO (100, 250 micrograms). Cytoplasmic superoxide dismutase (SOD) activity increased from control of 286 to 337 and 335 units/lung at Days 12 and 19, respectively, but decreased to 228 units/lung at Day 33; mitochondrial SOD activity increased at Day 12 from control of 57 to 71 units/lung and then decreased at Days 26 and 33 to 42 and 33 units/lung, respectively. Glutathione peroxidase (GP) and glutathione reductase (GR) activities rose from their control values of 1161 and 1151 to 1561 and 2287 units/lung at Day 12, respectively; thereafter, GR activity decreased to 512 and 462 units/lung at Days 19 and 26, respectively. Glutathione transferase declined at Day 12 but increased at Day 26 after initial treatment. Glucose-6-phosphate dehydrogenase activity declined from control of 1071 to 693 units/lung at Day 2 and returned to control thereafter. Catalase activity remained unaffected. Hydroxyproline was increased from 903 micrograms/lung in control to 1080, 1301, 1195, and 1148 micrograms/lung at Days 12, 19, 26, and 33, respectively. Malonaldehyde increased from 40 nmole/lung in control to 70 and 113 nmole/lung at Days 12 and 33, respectively. The ratio of right ventricle to left ventricle and septum increased significantly from control of 0.277 to 0.318 at Day 33. Histopathology at Days 2 and 4 revealed peribronchiolar and arteriolar inflammation, and diffuse alveolitis. By Day 12 there were thickened alveolar septa and foci of fibrotic consolidation.

Morphogenesis of the respiratory bronchiole in rhesus monkey lungs

The epithelium of the respiratory bronchiole in the adult rhesus monkey consists of two populations: a pseudostratified epithelium with basal, mucous goblet, and ciliated cells located near the pulmonary artery (PA); and a simple cuboidal epithelium composed only of nonciliated bronchiolar epithelial (or Clara) cells in areas away from the PA. This study describes the pattern of differentiation of these two epithelial populations, and their relationship to the PA and to the time of appearance of alveoli in the respiratory bronchiole of the rhesus monkey during the period of 90-125 days gestational age (DGA). These events were related to changes in the adjacent parenchyma. Dissected airways of infusion-fixed, critical-point-dried lungs were evaluated by scanning microscopy followed by light microscopy of the same airways. At 54% of gestation (90 DGA), the distal airway was lined by a mixture of ciliated and nonciliated cells. By 67% of gestation (110 DGA), the ciliated cells were confined to the epithelium over the PA. The underlying connective tissue initially was cellular containing few fibers but was fibrous by 76% of gestation (125 DGA). Alveolarization began near the most distal cartilage at 57% of gestation (95 DGA), the same period at which secondary septation occurred in the distal acinus. Thus, alveolarization occurred simultaneously in two centers: 1) the proximal centriacinar region in the vicinity of the most distal cartilage and 2) the distal lung parenchyma. The duration of centriacinar alveolarization was short, approximately 5 days.

Effects of repeated administration of N-acetyl-L-cysteine on sulfhydryl levels of different tissues and bleomycin-induced lung fibrosis in hamsters

N-Acetyl-L-cysteine (NAC), 50, 100, 200, or 400 mg/kg, was injected intraperitoneally once a day for 13 days. No change was seen in the total sulfhydryl (TSH) and nonprotein sulfhydryl (NPSH) contents of the liver, kidney, and plasma at any dose. The heart TSH level remained unchanged, but the NPSH level was increased from the control value of 16 nmol/mg to 18, 19, and 18 nmol/mg protein at 50, 100, and 200 mg/kg, respectively. The lung TSH and NPSH levels both were increased from the control values of 65 and 8 nmol/mg to 80 and 16 nmol/mg protein, respectively, at 200 mg/kg. The lung TSH level at 400 mg/kg NAC was not changed, but the NPSH level increased to 13.5 nmol/mg protein. The ratio of TSH to NPSH levels in the liver and kidney was 4:1, whereas in the lung and heart it was 7:1 and 8:1, respectively. Based on amount per milligram of protein, TSH and NPSH levels were highest in the liver, followed by the amounts in the kidney, heart, and lung. The lung had the lowest level of TSH and NPSH. The daily treatment with NAC (200 mg/kg) for 13 days after and 2 days before intratracheal injection of bleomycin (7.5 U/kg) had little effect on lung collagen accumulation. The lung collagen level measured as hydroxyproline in bleomycin and in NAC plus bleomycin was significantly increased to 175% and 183% of the control levels, respectively. There was no difference in the lung hydroxyproline content between the control and NAC groups. The histopathology study also revealed no marked difference between the bleomycin and bleomycin plus NAC groups. Alternatively, treatment with NAC (200 mg/kg) for 13 days before bleomycin made the animals more susceptible to bleomycin toxicity and tended to add to the bleomycin-induced accumulation of collagen in the lung. NAC per se caused no mortality at any dose. The lung TSH and NPSH levels in bleomycin-treated (7.5 U/kg) hamsters were increased to 136% and 111% of control, respectively, whereas the TSH and NPSH levels both were increased to 155% of the levels of their respective controls in hamsters in the NAC plus bleomycin group. The differential effects of NAC treatment on the sulfhydryl content of tissues, the treatment's inability to alter the course of bleomycin-induced lung inflammation and collagen accumulation, and the potential for exacerbation of lung toxicity in response to repeated administration of NAC before exposure to fibrogenic agents are discussed.

Distal airway remodeling in rats chronically exposed to ozone

The morphologic changes in the centriacinar region of lungs from 14 rats exposed to either filtered air (8) or 0.95 ppm ozone (6) 8 hours daily for 90 days were examined morphologically and morphometrically. Rats were killed with an overdose of sodium pentobarbital administered intraperitoneally, the trachea cannulated, and thoracic viscera and lungs removed from the chest. Lungs were fixed via intratracheal instillation of a paraformaldehyde/glutaraldehyde cacodylate buffered fixative at 30 cm water pressure. Lung volumes were determined by weight displacement and the left lung lobe was sectioned transversely into 12 slabs. Three slabs from the cranial, middle, and caudal thirds of the lobe were embedded in paraffin and studied by light microscopy. With these sections, we estimated the volume of proximal bronchiole, terminal bronchiole, respiratory bronchiole, and combined alveolar duct/sac within the lung. Bronchioles dissected from preselected regions of the right middle lobe were studied by transmission electron microscopy. Dissected terminal airways were sectioned in a longitudinal plane through their midlumen. From these dissected airways, 4 subregions of the centriacinus were then examined: (1) terminal bronchiole, (2) respiratory bronchiole, (3) centriacinar alveolar duct wall, and (4) centriacinar alveolar septa. The results of this study showed that after chronic ozone exposure, there was a 13 to 21% decrease in terminal bronchiole luminal diameter but no significant change in total terminal bronchiole volume. The most notable change was a 3.4-fold increase in respiratory bronchiole volume. Analysis of measured volume and diameter changes in the terminal bronchiole, coupled with volume increases in respiratory bronchiole, support the conclusion that respiratory bronchiole (RB) is formed from the centriacinar alveolar duct. Morphologic parameters supporting this conclusion included the presence of fused basement membrane beneath reactive bronchiolar epithelium in the RB, the presence of similar basal laminar changes in both the RB and proximal alveolar duct septal tips, and the observation that most severe epithelial damage and inflammation occurred in the most proximal alveolar duct rather than in the terminal bronchiole. A major conclusion of this study is that the focus of the most severe injury within the acinus appears to shift distally as respiratory bronchiole segments are formed. Hence most of the damage occurs at the tips of alveolar septa at the respiratory bronchiole-alveolar duct junction.

Effect of murine gamma interferon on the cellular responses to bleomycin in mice

Because in vitro studies have shown inhibition of fibroblast proliferation and collagen synthesis by interferon, we tested the hypothesis that murine gamma interferon inhibits bleomycin-induced pulmonary fibrosis in mice. Mice were divided into the following groups: saline plus vehicle (27), saline plus interferon (29), bleomycin plus vehicle (26), and bleomycin plus interferon (26). Bleomycin or saline were given intratracheally once at the beginning of the experiment and vehicle (phosphate-buffered saline) or interferon was given intramuscularly daily. Mice were killed at 14 or 21 days of the experiment. About half of the mice from each group were used for collagen biochemistry and half for bronchoalveolar lung lavage, transmission electron microscopy (TEM), and morphometry. Hydroxyproline content showed a significant reduction in bleomycin plus interferon compared to bleomycin plus vehicle mice at 21 days. The saline plus vehicle and saline plus interferon mice showed no difference in hydroxyproline content. Similarly, bronchoalveolar lavage showed no differences between saline plus vehicle and saline plus interferon mice; however, all mice treated with bleomycin showed significant increases in total cells as compared to saline treated mice. At 14 and 21 days in bronchoalveolar lavage there were significantly more lymphocytes in bleomycin plus interferon compared to bleomycin plus vehicle mice. In bronchoalveolar lavage, there were usually fewer neutrophils, monocytes and macrophages in bleomycin plus interferon compared to bleomycin plus vehicle mice. Morphometric estimates of the volume of lesion within lung showed no significant differences among the bleomycin treated groups. Stainable collagen fibers were less, but not significantly, in the bleomycin plus interferon compared to bleomycin plus vehicle mice. The number of fibroblasts per volume of lesion was significantly decreased at 14 and 21 days in bleomycin plus interferon compared to bleomycin plus vehicle mice. The total volume of lymphocytes in interstitial lesions was significantly greater at 14 and 21 days in bleomycin plus interferon mice compared to bleomycin plus vehicle mice. These results suggest an inhibitory action of gamma interferon on collagen accumulation and fibroblast proliferation associated with lymphocyte accumulation in the lungs of mice following bleomycin administration.

Nonolfactory surface epithelium of the nasal cavity of the bonnet monkey: a morphologic and morphometric study of the transitional and respiratory epithelium

The purpose of the present study was to characterize ultrastructurally the nonolfactory nasal epithelium of a nonhuman primate, the bonnet monkey. Nasal cavities from eight subadult bonnet monkeys were processed for light microscopy, and scanning and transmission electron microscopy. Nonolfactory epithelium covered the majority of the nasal cavity and consisted of squamous (SE), transitional (TE), and respiratory epithelium (RE). Stratified SE covered septal and lateral walls of the nasal vestibule, while ciliated pseudostratified RE covered most of the remaining nasal cavity. Stratified, nonciliated TE was present between SE and RE in the anterior nasal cavity. This epithelium was distinct from the other epithelial populations in abundance and types of cells present. TE was composed of lumenal nonciliated cuboidal cells, goblet cells, small mucous granule (SMG) cells, and basal cells, while RE contained ciliated cells, goblet cells, SMG cells, basal cells, and cells with intracytoplasmic lumina lined by cilia and microvilli. TE and RE contained similar numbers of total epithelial cells and basal cells per millimeter of basal lamina. TE was composed of more SMG cells but fewer goblet cells compared to RE. We conclude that nonolfactory nasal epithelium in the bonnet monkey is complex with distinct regional epithelial populations which must be recognized before pathologic changes within this tissue can be assessed adequately.

Response of the macaque nasal epithelium to ambient levels of ozone. A morphologic and morphometric study of the transitional and respiratory epithelium

Although ozone (O3)-induced bronchiolitis has been morphologically characterized, effects of O3 on the upper respiratory tract have not been thoroughly investigated. The purpose of this study was to determine whether exposures to ambient levels of O3 induce lesions in the nasal mucosa. Bonnet monkeys were exposed to 0.00, 0.15, or 0.30 ppm O3 for 6 or 90 days, 8 hours/day. After exposure, nasal mucosa was processed for light and electron microscopy. Quantitative changes were evident in the nasal transitional and respiratory epithelium. At 6 or 90 days of exposure to 0.15 or 0.30 ppm O3 lesions consisted of ciliated cell necrosis, shortened cilia, and secretory cell hyperplasia. Inflammatory cell influx was only present at 6 days of exposure. Ultrastructural changes in goblet cells were evident at 90 days. Ambient levels of O3 can induce significant nasal epithelial lesions, which may compromise upper respiratory defense mechanisms.

Quantitative histochemistry of mucosubstance in tracheal epithelium of the macaque monkey

Experimentally applied irritants and chronic respiratory diseases appear to alter the amount and composition of secretory cell product in surface epithelium and submucosal glands of pulmonary airways. Previous methods used to quantify these changes have been very time-consuming or have not measured the same components of the airway wall. The present study describes a rapid, reproducible, and standardized automated method for quantifying secretory products. The tracheas from eight macaque monkeys were fixed with glutaraldehyde-paraformaldehyde, embedded in glycol methacrylate, serially sectioned at 2 microns, and histochemically stained to demonstrate neutral, sialylated, and sulfated mucosubstances in the cartilaginous, intercartilaginous, and membranous regions of both proximal and distal trachea. Volume densities were determined using an image analyzer and are expressed as volume of stained mucosubstance per unit surface area of epithelial basal lamina. Comparison of the automated method to manual point counting and evaluation of internal variance showed that the automated method had a twelve-fold increase in efficiency with no significant differences in measurements. After weighting the values of each region according to their anatomical contribution, the total secretory product (TSP) for the entire trachea was determined. Periodate-reactive acid material predominated (73%) in luminal surface epithelium, and neutral material predominated (78%) in submucosal glands. Surface epithelium contained 66% of the TSP. The greater contribution by surface epithelium and predominance of acid mucins there resulted in a TSP from the trachea that consisted of 59% acid material (most of which was sulfated) and 41% neutral material. The method proved to be a valid, reproducible, and rapid technique for evaluating variability in abundance of mucosubstances within airway epithelium.

Effects of an ambient level of ozone on primate nasal epithelial mucosubstances. Quantitative histochemistry

Despite the absorption of inhaled oxidant gases by the nasal cavity, little effort has been made to characterize the effects of these oxidants on the nasal mucosa. This study defines the effects of ambient concentrations of ozone on the character and amount of mucosubstances in epithelium of nasal mucosa. Bonnet monkeys were exposed to 0.00 or 0.15 ppm O3 (8 hr/day) for 6 or 90 days, anesthetized, and exsanguinated. Nasal cavities were fixed with Karnovsky's fixative, decalcified, and processed for light microscopy, and sections were stained with alcian blue (pH 2.5)/periodic acid-Schiff or high iron diamine. Volume densities of secretory material in nasal epithelium were determined with the use of a Quantimet 900 image analyzer. After 6 days' exposure there were significant increases in both acidic and neutral glycoconjugates stored in transitional and respiratory epithelium. After 90 days there was significantly less mucosubstance than at 6 days. Only in the transitional epithelium did the total and sulfated mucosubstance remain greater than that of controls. Nasopharyngeal epithelium was minimally affected after 6 days of O3 and unchanged after 90 days. It is concluded that exposures to ambient levels of O3 induce significant changes in the stored secretory product of nasal epithelium.

Increases in severity of lung damage and mortality by treatment with cyclo and lipoxygenase inhibitors in bleomycin and hyperoxia model of lung injury in hamsters

Effects of ibuprofen (I), a cyclooxygenase inhibitor, and of nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, on bleomycin (B) and hyperoxia (H) induced acute lung damage and mortality were studied in hamsters. Hamsters, after receiving bleomycin, 0.25 unit, intratracheally were treated subcutaneously with vehicle (BHV group), ibuprofen, 10 mg/kg, (BHI group) or NDGA 10 mg/kg (BHNDGA group) and then exposed to 70% oxygen (O2) for 72 h. Daily treatment in each case continued for 14 days. The cumulative mortality at 0, 2, 4, 7, and 14 days after O2 exposure was as follows: 0, 5, 13, 26, and 50%, in BHV; 0, 10, 21, 33, and 67% in BHI; and 2, 21, 51, 71, and 92% in BHNDGA groups, respectively. The lung hydroxyproline content in pooled control hamsters averaged 721.1 +/- 22.3 (SE) micrograms/lung. The lung hydroxyproline content in animals in BHV, BHI, and BHNDGA groups was significantly increased at 4, 7, and 14 days after exposure when compared to controls. There were, however, no significant differences in the hydroxyproline content of the lungs among animals in BHV, BHI, and BHNDGA groups at any post-exposure time. Morphology of lungs of the BHV group showed an infiltrate of monocytes, lymphocytes, and some neutrophils (PMN) at 2 days but was composed primarily of monocytes and macrophages at 4, 7, and 14 days post-exposure. Multifocal fibrosis was observed at 7 days and was more diffuse by 14 days. Multifocal fibrosis in lungs from the BHI group was seen at 4 days with foci being larger at 7 and 14 days. Multifocal epithelial necrosis was observed at 14 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinogenicity of dietary aflatoxin M1 in male Fischer rats compared to aflatoxin B1

Aflatoxin M1 (AFM), an hydroxy metabolite of the potent carcinogenic mycotoxin aflatoxin B1 (AFB) is frequently found in milk and other dairy products. Sufficient amounts of AFM were produced to study the carcinogenicity of this compound. AFM was fed to male Fischer rats starting at 7 weeks up to 21 months of age. Agar-based semisynthetic diets contained 0.0, 0.5, 5.0, and 50.0 micrograms/kg of AFM or 50 micrograms/kg of AFB. Hepatocellular carcinomas were detected in two of 37 rats and neoplastic nodules were found in six of 37 rats fed 50 micrograms/kg AFM between 19 and 21 months. No nodules or carcinomas were observed in the lower AFM dose groups. Nineteen of 20 rats fed a diet containing 50 micrograms/kg of AFB developed hepatocellular carcinomas by 19 months of age. Carcinogenic potency of the aflatoxins was reflected by morphometric quantitation of foci detected in hematoxylin and eosin stained sections. Three rats fed the diet containing 50 micrograms/kg AFM developed intestinal carcinomas. None were observed in other groups. Under the conditions of this experiment AFM was found to be a weak hepatic carcinogen compared to AFB and to possess intestinal carcinogenicity.

Regional differences in quantities of histochemically detectable mucosubstances in nasal, paranasal, and nasopharyngeal epithelium of the bonnet monkey

Inhaled irritants induce secretory cell hyperplasia in nasal epithelium of animals. To characterize this response histochemically it is first important to know the histochemical character and distribution of epithelial mucosubstance in the normal nasal cavity. An automated image analyzing method was used to detect and quantitate acidic, neutral, and sulfated mucosubstances in the epithelium lining the nasal and paranasal airways of eight bonnet monkeys. Tissue sections 2 micron thick from defined regions of these airways were stained with either alcian blue/periodic acid-Schiff to demonstrate acid and neutral mucosubstances or high iron diamine to demonstrate sulfated mucins. Respiratory epithelium covering maxilloturbinates had the largest volume of stainable mucosubstance per unit surface area of basal lamina, whereas the maxillary sinus epithelium had the least. There was a general anteroposterior increase in the quantity of total epithelial mucosubstance along the septal and lateral walls of the nasal cavity, and there was more acidic than neutral mucosubstance in the posterior nasal airway than in the anterior. Epithelial mucosubstance in the maxillary sinus was predominantly neutral. Therefore, we conclude that there are substantial regional quantitative differences in stainable mucosubstances in the primate nasal epithelium which must be considered when examining nasal mucosa for irritant-induced changes in epithelial mucins.

Lung growth of the turkey, Meleagris gallopavo: II. Comparison of two genetic lines

Comparisons of lung growth in two genetic lines of turkeys, one unselected and one selected for increased body mass, were used to evaluate the lung's alteration in structure with changes in body form or physiology. Seventy-two male turkeys, 36 genetically selected for early rapid growth and large pectoral musculature, and 36 unselected birds, were killed at 12 different ages to compare lung growth in the two lines. Body weights and lung volumes were determined. A three-level cascade sampling system was used to prepare lung tissue for qualitative and quantitative observation by light microscopy. Allometric equations describing growth of lung volume and lung compartments relative to body weight in two phases (tissue proliferation and equilibrated growth) were compared between lines of turkey for differences in slopes or intercepts. Means of data for 112- and 420-day-old birds were also compared. There were no qualitative histological differences observed between lungs of the two lines of turkey, yet there were morphometric differences in lung growth relative to body weight. During equilibrated lung growth, there was less rapid growth of air and blood capillary volumes and surfaces relative to body weight in the selected than in the unselected turkey. The gas-exchange compartment did not enlarge concomitant with the large increase in muscle mass of the selected turkeys, while large-vessel volume and small-airway volume grew similarly to body weight in both turkey lines. We conclude that the lung of the selected line of turkeys did not show an enlarged gas-exchange compartment relative to the greater body muscle mass, but it did show enlarged vessels and conducting airways.

Lung growth of the turkey, Meleagris gallopavo: I. Morphologic and morphometric description

To describe lung growth qualitatively and quantitatively from prehatch to adulthood of an unselected line of turkey, a precocial avian species, 36 male turkeys, three in each age group, were killed at 22 and 25 days of incubation, on hatch day, and at 1, 4, 7, 10, 14, 21, 28, 112, and 420 days of age. Body weight and lung volume were measured. A three-level cascade sampling system was used to prepare lung tissue for morphologic and morphometric observation by light microscopy. Point and intersection counting were used to estimate volume and surface densities of lung compartments relative to lung volume. Absolute volumes and surfaces of lung compartments were calculated. Bilogarithmic regressions provided allometric equations to describe growth of the lung in three phases: Tissue proliferation--explosive growth of lung volume relative to body weight and of the gas-exchange compartment within the lung. At 22 days of incubation there were few air and blood capillaries and a great deal of tissue that looked like mesenchyme between the parabronchi. Within the 6 days prior to hatch, the surface area of air capillaries increased 11-fold and of blood capillaries 27-fold, whereas the volume of interparabronchial tissue decreased 58%. Equilibrated growth--from hatch day to 28 days of age, most lung compartments grew evenly with lung volume. Regulated growth--from 28 days of age to adult, all lung compartments, except large vessels and exchange compartment, grew more slowly than the entire lung. Interatrial septa lengthened and their epithelial covering thinned, infundibula became more apparent, and interparabronchial connective tissue reached a minimal volume density in the adult lung.

Severe pulmonary hypertension and arterial adventitial changes in newborn calves at 4,300 m

Some human newborns have a syndrome characterized by irreversible pulmonary hypertension and severe hypoxemia and by medial hypertrophy and adventitial thickening of pulmonary arteries. We considered that newborn calves made severely hypoxic might reproduce features of the human disease. When 2-day-old calves were placed at 4,300 m simulated altitude, pulmonary arterial pressure was increased and could be reversed by 100% O2. However, after 2 wk at 4,300 m, pulmonary arterial pressures were suprasystemic and there was right-to-left shunting probably through the foramen ovale and a patent but restrictive ductus arteriosus. Suprasystemic pulmonary pressure and hypoxemia persisted with 100% O2 breathing. Morphometrical examination of the lung arteries showed a markedly thickened adventitia with cellular proliferation and collagen and elastin deposition. There was increased medial thickness and distal muscularization of the pulmonary arteries associated with decreased luminal diameter. The rapid development of severe pulmonary hypertension and poor responsiveness to O2 was associated with increased arterial wall thickness, particularly involving the adventitia. Thus the pulmonary arterial circulation in these calves, which were placed at high altitude for 2 wk, exhibited features resembling persistent pulmonary hypertension in newborn infants.

Ozone-induced adaptive and reactive cellular changes in respiratory bronchioles of bonnet monkeys

To characterize the response of respiratory bronchioles (RBs) to chronic high ambient levels of ozone, bonnet monkeys were exposed for 90 days to 0, 0.4, or 0.64 ppm ozone (UV photometric standard; 3 monkeys/exposure). Morphologic changes in respiratory bronchiolar epithelium and interstitium were evaluated quantitatively at both the light and transmission electron microscopic levels. Significant changes in respiratory bronchioles following exposure included: a thicker wall and a narrower lumen, a thicker epithelial compartment and a much thicker interstitial compartment, shifts in epithelial cell populations with many more nonciliated bronchiolar epithelial cells and fewer squamous type I epithelial cells, larger nonciliated bronchiolar epithelial cells with a larger complement of cellular organelles associated with protein synthesis, greater amounts of both interstitial fibers and amorphous ground substance, greater numbers of interstitial smooth muscle cells per epithelial basal lamina surface area, and greater volumes of interstitial smooth muscle, macrophages, mast cells, and neutrophils per epithelial basal lamina surface area. These observations imply that chronic ozone exposure causes a concentration-dependent reactive peribronchiolar inflammatory response and an adaptive response consisting of hypertrophy and hyperplasia of the nonciliated bronchiolar cell.

Morphometry of the coronary microvasculature of the canine left ventricle

The objective of this study was to test for the presence of transmural gradients of various components of the coronary microvasculature of the canine left ventricle. In order to achieve study objectives, the heart and coronary circulation were fixed in a reproducible state of myocardial and vascular tone (diastolic cardiac arrest and maximal coronary vasodilation). Morphometric methods which treat the coronary microvasculature as anisotropically arranged structures were applied for quantitative structural analysis. Eight dog hearts were fixed with a glutaraldehyde-cacodylate-buffered fixative by retrograde perfusion of the aorta with the heart in diastolic arrest and with maximal coronary vasodilation. Tissue samples were taken from areas near to the anterior and posterior papillary muscles from the subendocardium, subepicardium, and intermediate transmural locations. Morphometric results showed a homogeneously arranged array of microvascular and myocardial components with no significant differences in any of the primary morphometric measurements, down to the ultrastructural level, in myocytes relative to transmural location. The results suggest that transmural differences in coronary blood flow are not due to transmural structural differences but rather are due to physiological regulatory mechanisms of coronary blood flow. Further, the results indicate that failure to correct for anisotropy of myocardial structures can lead to erroneous conclusions concerning the structural basis of function in the heart.

Immunoglobulin containing cells in the tracheobronchial tree of cattle: relationship to age

The cells of the pulmonary immune system of cattle were examined using an immunoperoxidase technique to identify cytoplasmic immunoglobulins. Cells reacting immunohistochemically with bovine IgG1, IgG2, IgA and IgM antisera were quantified in formalin-fixed paraffin embedded tissues from systematically selected sites within the tracheobronchial tree. Non-pneumonic lungs were selected for study from five groups of cattle which ranged in age from neonatal calves to aged adult cattle. Age associated differences were found. Neonatal calves lacked immunoglobulin containing cells (ICC). The numbers of ICC in 18-month-old cattle were significantly greater than in other age groups. The relative frequency of each immunoglobulin class among the cells of the airway mucosa was IgA greater than IgG1 greater than IgG2 greater than IgM for all cattle four months and older (n = 20) with an IgA to IgG1 ratio of 3.46. All airway categories from trachea to bronchiole had similar proportions of cells in each immunoglobulin class although the cell density declined in the distal airways.

Effects of a calmodulin inhibitor on bleomycin-induced lung inflammation in hamsters. Biochemical, morphometric, and bronchoalveolar lavage data

Previous studies have shown that bleomycin-induced pulmonary fibrosis is accompanied by elevated levels of calcium and calmodulin, which are important in the regulation of many biologic processes. The authors have further extended these observations and assessed the effect of a calmodulin inhibitor, trifluoperazine, on bleomycin-induced lung damage with biochemical, morphometric, and bronchoalveolar lavage techniques. The cumulative mortality due to bleomycin was not significantly reduced in animals receiving trifluoperazine. Trifluoperazine had no apparent effect on lung levels of collagen and DNA elevated by bleomycin. However, morphometric studies showed that the volume density of the lesion, the volume of amorphous material and interstitial inflammation, and the number of monocytes within lesions were less in the lungs of bleomycin-treated hamsters receiving trifluoperazine daily. When compared with hamsters treated with bleomycin alone, animals treated with both bleomycin and trifluoperazine had significantly fewer lymphocytes in their bronchoalveolar lavage fluid. The data suggest that trifluoperazine reduced the acute inflammation which accompanies bleomycin pneumotoxicity but did not affect the subsequent development of pulmonary fibrosis. It has been postulated that the observed antiinflammatory action of trifluoperazine may be due to inhibition of calmodulin-dependent leukocyte functions.

Bronchus associated lymphoid tissue in the lungs of cattle: relationship to age

The occurrence and morphological features of bronchus associated lymphoid tissue (BALT) were examined by light and electron microscopy in the non-pneumonic left lungs of five age groups of cattle from neonate to aged adult. The amount of BALT was correlated with age. It was absent in neonatal lungs and increased progressively with age until it declined in aged adult cattle. Within age groups the occurrence and morphology of BALT was variable. Widely scattered lymphoid aggregates were the predominant morphological type of BALT in the bovine lung. Follicular development in BALT foci was less frequent and quite variable within individual lungs. Morphologically distinct lymphoepithelium overlying BALT foci could not be demonstrated in non-pneumonic bovine lungs.

Synergistic interaction of ozone and respirable aerosols on rat lungs. I. Importance of aerosol acidity

A synergistic interaction, as defined by biochemical and morphological criteria, between ozone (or NO2) and respirable aerosols of ammonium sulfate or sulfuric acid has been described previously. Experiments in the present paper show that it is the acidity, not the sulfate content, of the aerosol that is responsible for such synergy; neutral aerosols of Na2SO4 or NaCl do not elicit synergistic effects when combined with ozone. Aerosol size (and, therefore, site of deposition in the lung) is also an important determinant of synergy with ozone; 0.5 micron mass median aerodynamic diameter (MMAD) aerosols are effective whereas 0.02 micron MMAD aerosols are not. The synergistic interaction between ozone and acidic aerosols could be demonstrated by biochemical and toxicological criteria in addition to those we have previously reported, for example increases in whole lung protein content and free (acid-soluble) proline content of lungs. A synergistic interaction has been demonstrated at concentrations of 0.64 ppm (1.3 mg/m3) of ozone and 1 mg/m3 of acid aerosol in this study. We conclude that acidity of an aerosol determines whether or not it interacts synergistically with ozone, and that an aerosol size that impacts maximally upon the alveolar duct region of the lung is most active with ozone.

Tocainide suppression of immune-complex-mediated dermal inflammation: comparison with prostaglandin E1

Local anesthetic agents have been shown to alter a variety of polymorphonuclear leukocyte (PMN) functions and may be useful as anti-inflammatory agents. We compared the anti-inflammatory effects of therapeutic doses of the recently released local anesthetic-antiarrythmic drug tocainide to pharmacologic doses of prostaglandin E1 (PGE1) on immune-complex-mediated dermal inflammation in female Sprague-Dawley rats. Intense dermal inflammation was produced using a classic reverse passive Arthus reaction, and the inhibition of PMN accumulation in the subdermis was quantitated in biopsy samples taken 2.5 hr after the reaction was initiated and the drug was given. Using a light microscope with a counting grid, biopsy sections were randomly sampled in a blinded fashion and an inflammation index equal to the ratio of PMNs to fibroblasts was determined for each animal. The mean inflammation index in 10 animals given 25 mg of tocainide (mean serum level = 14.6 micrograms/ml) was 9.3 +/- 1.2 (+/- SEM), which was significantly less than the index of 17.7 +/- 2.5 in 10 control animals (P less than 0.025). Similarly, the five animals that received either 500 or 250 micrograms of PGE1 had a significantly reduced index, with the effect of 250 micrograms PGE1 comparable to the effect of the tocainide. These findings suggest that therapeutic levels of tocainide reduce the accumulation of PMNs in immune-complex-mediated dermal inflammation; thus, local anesthetic agents may be useful in the treatment of certain inflammatory disorders.

Analysis of bronchoalveolar lavage fluid from bleomycin-induced pulmonary fibrosis in hamsters

The purpose of this study was to analyze the cellular and noncellular components of bronchoalveolar lavage fluid (BALF) at varying times during the development of pulmonary fibrosis induced by bleomycin. Hamsters were killed and lavaged in situ following the administration of a single intratracheal injection of 1 unit of bleomycin or an equivalent volume of sterile isotonic saline. The results show that the total cell counts in the BALF of bleomycin-treated hamsters, as compared with controls, were increased 7.7, 4.4, 2.4, 1.6, and 1.9-fold at 2, 4, 7, 14, and 21 days after treatment, respectively. The predominant cell types in the BALF of control animals were macrophages which constituted 84% of the total cells, followed by lymphocytes, 11%. The predominant cell types in the BALF of bleomycin-treated animals were polymorphonuclear leukocytes (PMN) which constituted 65% at two days and approximately 50% of the total at 4, 7, and 14 days; at 21 days macrophages were the predominant cell type constituting 50%, followed by lymphocytes at 30%. However, the total number of lymphocytes was not increased at 21 days compared to previous times. The noncellular protein content of BALF from bleomycin-treated hamsters, an index of pulmonary vascular permeability, was increased to 224, 559, 637, and 270% of control (2.7 mg/lung) at 2, 4, 7, and 14 days after treatment, respectively, and returned to control levels at 21 days. The acid phosphatase activity in the supernatant of BALF of bleomycin-treated animals was significantly increased to 181, 181, 199, 176, and 125% of control (258 units/lung) at 2, 4, 7, 14, and 21 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Relative growth of the anulus fibrosus and nucleus pulposus in human and kitten fetuses

Growth in volume of the anulus fibrosus (AF) and nucleus pulposus (NP) was quantified using serial histological sections of human and kitten fetuses. Fetal intervertebral discs were studied that had clearly outlined AF and NP. Regression equations were calculated and graphs plotted by microcomputer. An increase in surface areas of these intervertebral structures was also recorded; however, volume was a better indicator of relative growth than was surface area. The AF volume of the fetal human increased more in proportion to the intervertebral disc than it did for the fetal kittens. There was significantly slower growth of the human NP compared to the kitten NP when related to the total intervertebral disc. The analysis for each species was done separately. Comparisons of the growth relationships of humans and kittens for the AF and NP were related to crown-rump length as the independent variable, and were different at the p less than or equal to 0.01 level of significance. The thoracic intervertebral discs were emphasized due to species-specific differential growth of the AF. The intercapital ligament (IC) was separated from mesenchyme over the dorsal surface of the kitten AF, and this affected the relationships of AF and NP volumes when compared to humans. Use of human histological sections is essential in the study of differential growth of the human vertebral column because fetal kittens have an IC that affects relative growth of both AF and NP.

Peribronchiolar fibrosis in lungs of cats chronically exposed to diesel exhaust

This study reports the quantitative changes in the pulmonary proximal acinar region following chronic exposure to diesel exhaust and following an additional 6 months in clean air. Cats (13 months of age) from a minimum disease colony were exposed to clean air (eight cats for 27 months and nine cats for 33 months), diesel exhaust for 8 hours/day, 7 days/week (nine cats for 27 months), or diesel exhaust for 27 months followed by 6 months in clean air (10 cats). Morphologic and morphometric evaluation using light microscopy and scanning and transmission electron microscopy revealed two major exposure-related lesions in proximal acinar regions of lungs of cats: peribronchiolar fibrosis associated with significant increases in lymphocytes, fibroblasts, and interstitial macrophages containing diesel particulate-like inclusions and bronchiolar epithelial metaplasia associated with the presence of ciliated and basal cells and alveolar macrophages containing diesel particulate-like inclusions. Peribronchiolar fibrosis was greater at the end of the 6 months in clean air following exposure, whereas the bronchiolar epithelial metaplasia was most severe at the end of exposure. Following an additional 6 months in clean air the epithelium more closely resembled the control epithelial cell population. The labeling index of terminal bronchiolar epithelium was significantly increased at the end of exposure but was not significantly different from controls or exposed cats following an additional 6 months in clean air. The ultrastructural appearance of epithelial cells remained relatively unchanged following diesel exhaust exposure with the exception of diesel particulate-like inclusions. Total lung collagen, expressed as hydroxyproline per left caudal lobe, was apparently increased (although the difference was not significant) in lungs of cats allowed to recover 6 months in clean air. Newly synthesized collagen (evaluated as the amount of cross-link-derived aldehydes in collagen) was significantly increased to more than twice the control values. The ratio of collagen aldehydes to hydroxyproline was also significantly increased. These observations imply that chronic exposure to diesel exhaust has a persistent fibrogenic effect on the proximal acinar region of the lung.