Showing papers on "Respiratory epithelium published in 1988"

Cyclic AMP-dependent protein kinase opens chloride channels in normal but not cystic fibrosis airway epithelium

Abstract: Chloride (Cl-) secretion by the airway epithelium regulates, in part, the quantity and composition of the respiratory tract fluid, thereby facilitating mucociliary clearance. The rate of Cl- secretion is controlled by apical membrane Cl- channels. Apical Cl- channels are opened and Cl- secretion is stimulated by a variety of hormones and neurotransmitters that increase intracellular levels of cyclic AMP (cAMP). In cystic fibrosis (CF), a common lethal genetic disease of Caucasians, airway, sweat-gland duct, secretory-coil and possibly other epithelia are anion impermeable. This abnormality may explain several of the clinical manifestations of the disease. The Cl- impermeability in CF-airway epithelia has been localized to the apical cell membrane, where regulation of Cl- channels is abnormal: hormonal secretagogues stimulate cAMP accumulation appropriately but Cl- channels fail to open. Here we report that the purified catalytic subunit of cAMP-dependent protein kinase plus ATP opens Cl- channels in excised, cell-free patches of membrane from normal cells, but fails to open Cl- channels in CF cells. These results indicate that in normal cells, the cAMP-dependent protein kinase phosphorylates the Cl- channel or an associated regulatory protein, causing the channel to open. The failure of CF Cl- channels to open suggests a defect either in the channel or in such an associated regulatory protein.

Measurement of Pseudomonas aeruginosa phenazine pigments in sputum and assessment of their contribution to sputum sol toxicity for respiratory epithelium.

Abstract: The phenazine pigments pyocyanin and 1-hydroxyphenazine were resolved by high-pressure liquid chromatography from the sputum sol phase from 9 of 13 patients with cystic fibrosis or bronchiectasis colonized by Pseudomonas aeruginosa. The concentrations measured were each sufficient to inhibit ciliary beating in vitro and contributed a significant proportion of sol phase toxicity for respiratory epithelium.

A clinical and pathologic study of chronic sinusitis: The role of the eosinophil

Abstract: Evidence exists that the eosinophil plays an important role in mediating injury to bronchial epithelium in chronic asthma. Here, the role of the eosinophil in chronic inflammatory disease of the paranasal sinuses was studied with tissue from patients who underwent surgery for chronic sinusitis. Paranasal tissue from patients with chronic asthma and/or allergic rhinitis was extensively infiltrated with eosinophils. Immunofluorescent studies demonstrated a striking association between the presence of extracellular deposition of major basic protein and damage to sinus mucosa. The histopathology of paranasal respiratory epithelium appeared similar to that described in bronchial asthma. These findings suggest that the eosinophil acts as an effector cell in chronic inflammatory disease of paranasal respiratory epithelium. Thus, sinus disease in patients with asthma may be due to the same mechanisms that cause damage to bronchial epithelium.

Eosinophil Recruitment into Guinea Pig Lungs after PAF-acether and Allergen Administration: Modulation by Prostacyclin, Platelet Depletion, and Selective Antagonists

Abstract: Intravenous administration of PAF-acether to the guinea pig induces bronchoconstriction, hypotension, intravascular platelet aggregation, endothelial disruption, and platelet and neutrophil diapedesis. These effects are followed within 1 h by an eosinophilic infiltration into the bronchial walls, which was also noted after the administration of antigen to passively sensitized guinea pigs. Bronchoconstriction and eosinophil infiltration are 2 major features of asthma, and selective bronchial eosinophilia characterizes late asthmatic reactions. We compared the histologic effects of PAF-acether 6 and 24 h after its intravenous injection with those of experimental passive anaphylactic shock, which is used as a model for asthma. Six hours after PAF-acether or antigen (ovalbumin) administration, a marked lung eosinophil infiltration, particularly in the bronchial walls, was noted, together with mucous plugs containing eosinophils in the bronchial lumen. Epithelial desquamation was followed after 24 h by mucous metaplasia of the bronchial epithelium. These effects were not observed when the inactive metabolite lyso-PAF was used. Our results agree fully with the suggestion that the eosinophil mediates the pathophysiology of bronchial asthma and releases materials toxic for the respiratory epithelium. Two PAF-acether antagonists (BN 52021 and WEB 2086) prevented the eosinophil infiltration triggered by PAF-acether and by antigen. When PAF-acether or ovalbumin were injected into guinea pigs after antiplatelet serum or prostacyclin, the eosinophil infiltration was significantly reduced, suggesting that platelets or another adenylate cyclase-sensitive cell are important for the subsequent PAF-acether-induced eosinophil infiltration. Our results support an essential role for PAF-acether in an experimental model of allergic asthma.

Human eosinophil major basic protein causes hyperreactivity of respiratory smooth muscle: role of the epithelium

Abstract: Major basic protein (MBP), one of several cationic proteins associated with the eosinophil granule, is cytotoxic to respiratory epithelium and is present in the sputum of asthmatics and on damaged bronchial epithelium from patients dying of asthma. The present experiments were performed in order to determine the effects of MBP on the responsiveness of airway smooth muscle. Rings of guinea pig trachea, in some of which the epithelium had been gently removed by rubbing, were incubated for 5 h in modified Krebs-Ringer bicarbonate solution containing buffer or human MBP (100 micrograms/ml). The tracheal rings were then suspended for isometric tension recording in organ chambers filled with Krebs-Ringer solution containing indomethacin. MBP did not affect the reactivity of rings in which the epithelium had been removed, but significantly augmented that of unrubbed rings to acetylcholine and histamine. The results suggest that MBP, by inhibiting the function of epithelial but not smooth muscle cells, causes hyperreactivity of respiratory smooth muscle, which may contribute to the hyperreactivity observed in chronic respiratory disease.

Neurogenic inflammation in the rat trachea. I. Changes in venules, leucocytes and epithelial cells.

Abstract: This study was done to characterize the morphological changes in the respiratory mucosa that occur in neurogenic inflammation, which is a type of inflammation mediated by substances released from sensory nerves. Neurogenic inflammation was produced in the trachea and bronchi of atropine-treated Long-Evans rats by electrically stimulating the left or right superior laryngeal and vagus nerves. This procedure is known to increase vascular permeability in the airways, presumably as a consequence of antidromic activation of sensory vagal axons (Lundberg & Saria, 1982). By using a particulate tracer (Monastral blue, 30 mg kg-1 i.v.) that does not cross the walls of normal tracheal blood vessels but does cross the endothelium of abnormally permeable vessels, it was possible to identify which blood vessels were affected in neurogenic inflammation. Light and electron microscopic examination of tracheas prepared after 2 or 5 min of vagal stimulation revealed that postcapillary venules and collecting venules 7-80 micron in diameter were labelled by extravasated Monastral blue but capillaries, arterioles, and larger venules were not. Venules from which the extravasation occurred had gaps as wide as 1.5 micron between endothelial cells. Most of the abnormally permeable venules were located just beneath the airway epithelium in regions between the cartilaginous rings. Extravasation also occurred from venules in the mucosa overlying the posterior membrane of the extrathoracic trachea, but little occurred in the posterior membrane of the intrathoracic trachea. After unilateral vagal stimulation, vascular permeability was increased on both sides of the trachea; it was also increased in first through fourth order bronchi but only on the side of stimulation. Leucocytes (principally monocytes and neutrophils) were adherent to the endothelium of some of the abnormally permeable venules. Erythrocytes and platelets also were adherent to the walls of some venules. These changes in venules were accompanied by a degranulation of epithelial secretory cells, widening of the spaces between tracheal epithelial cells, and probably an increase in epithelial permeability. Neurogenic inflammation in the trachea and bronchi of rats is thus characterized by increased permeability of postcapillary venules and collecting venules in specific regions of the respiratory mucosa as well as adherence of leucocytes, erythrocytes and platelets to the endothelium of these venules and prominent changes in the respiratory epithelium.

Proliferation and differentiation in mammalian airway epithelium.

Abstract: The infrequency of mitotic figures led to dispute amongst early workers as to the occurrence of cell division in adult mammalian airway epithelium [30, 63, 83, 227]. It was not until 1951 that quantitative work in the respiratory tract began to concentrate on the distal (i.e. respiratory) portion of the lung (reviewed by BERTALANFFY (20, 21], KAUFFMAN [132], and MASSE et al. [159]). Studies of the lining epithelium of conducting airways soon followed [I I, 25, 26, 27, 32, 38, 148, 208, 230]. The present review summarizes the results of many studies of cell division and differentiation in conducting airway epithelium. I t is divided into three major sections: I) general principles and techniques used in assessment of cell kinetics; 2) normal proliferation and differentiation in conducting airways and 3) effects of irritants and carcinogens, mechanical trauma, drugs, infection and physiological factors on cell proliferation and differentiation. Proliferation and differentiation, which occur during airway development, are not discussed here: the interested reader is referred to the following papers and reviews [24, 47, 119, 129, 132, 207, 237]. At least eight epithelial cell types are recognised in the lining epithelium of conducting airways and three in the epithelium lining the alveoli (for reviews see [41, 116, 117, 118]). In man the tracheobronchial surface epithelium is pseudostratified, ciliated and columnar

The effect of unilateral naris occlusion on cell dynamics in the developing rat olfactory epithelium

Abstract: The effect of unilateral naris occlusion on the cellular dynamics of developing olfactory epithelium was investigated in postnatal rats. Nares of rat pups, at 1, 5, and 10 d postnatally, were cauterized; after a 30 d survival period, the olfactory mucosa was examined histologically, and quantitative estimates were made of total number of receptor neurons (together with basal cells), supporting cells, and epithelial thickness. In each group, there were significant differences between occluded and patent sides in total numbers of neurons and in epithelial thickness but no difference in number of supporting cells. The differences were greater in the animals that had been occluded for 1–30 d than in the 5–35 or 10–40 d groups, suggesting that the earlier postnatal days are more sensitive to the effects of occlusion. We evaluated the number of mature olfactory neurons by staining immunohistochemically with an antibody against olfactory marker protein. There were no differences in the number of mature receptor neurons between the occluded and non-occluded sides, indicating the effect of naris occlusion was on the neurons in the immature and/or the “almost mature” population. Using 3H-thymidine autoradiography, we determined that there was a 40% reduction in the rate of neurogenesis in the animals occluded 1–30 d after birth. Further, the rate of cell proliferation in nasal respiratory epithelium declined by approximately the same amount.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma exudation and asthma.

Abstract: Several pieces of evidence support the view that exudation of plasma into the airway wall and into the airway lumen occurs in asthma. Vascular leakage of plasma results from inflammatory mediator-induced separation of endothelial cells in postcapillary venules belonging to the tracheobronchial circulation. Whereas proposed mediators of asthma induce reversible leakage, several antiasthma drugs exhibit antileakage effects in animals and humans. Potential consequences of plasma exudation are many. Mucosal/submucosal edema might contribute to airway hyperresponsiveness. Plasma exudate in the airway lumen in asthma may contribute to sloughing of epithelium, impairment of mucociliary transport, narrowing of small airways, and mucus plug formation. Exuded plasma may cause airway inflammation and constriction because of its content of powerful mediators, and chemoattractant factors and plasma proteins may condition the inflammatory cells abundant in asthmatic airways to release mediators in response to stimuli that otherwise would be innocuous to the cells. It is concluded that inflammatory stimulus-induced increase in macromolecular permeability of the tracheobronchial microvasculature and mucosa may be a significant pathogenetic mechanism in asthma and that the postcapillary venular endothelium and airway epithelium that regulate leakage of plasma are important effector cells in this disease.

Ozone-induced augmentation of eicosanoid metabolism in epithelial cells from bovine trachea.

Abstract: Epithelial injury and inflammation have been implicated in ozone-induced airway hyperresponsiveness. Because ozone is relatively insoluble and highly reactive, toxicologic effects of this compound may be limited to the plasma membranes of airway epithelium. We hypothesize that oxidant damage to epithelium may result in elaboration of various eicosanoids, which are known to alter airway smooth muscle responsiveness and epithelial cell functions (including ion transport). To examine eicosanoid metabolism after exposure to 0.1 to 10.0 ppm ozone, epithelial cells derived from bovine trachea were isolated and grown to confluency. Bovine tracheal cells in culture expressed differentiated features characteristic of epithelial cells, including a plasma membrane with a specialized polar morphology, an extensive network of filaments that were connected through intercellular junctional complexes, and keratin-containing monofilaments as determined by indirect immunofluorescent localization. Monolayers were alternately exposed to ozone and culture medium for 2 h in a specially designed in vitro chamber using a rotating inclined platform. Eicosanoid products were measured by the release of [3H]-labeled products from cells incubated with [3H]-arachidonic acid for 24 h before exposure and by the release of immunoreactive products into the cell supernatant. Both methods revealed ozone-induced increases in cyclooxygenase and lipoxygenase product formation with significant increases in prostaglandins E2, F2 alpha, 6-keto F1 alpha, and leukotriene B4. Release rates of immunoreactive products were dose-dependent, and ozone concentrations as low as 0.1 ppm produced an increase in prostaglandin F2 alpha. These findings are consistent with the hypothesis that ozone can augment eicosanoid metabolism in airway epithelial cells.

A possible role of airway epithelium in modulating hyperresponsiveness.

Abstract: 1. In order to examine the role of airway epithelium in the responsiveness of smooth muscle in man, we measured the contractile responses to acetylcholine (ACh), histamine, and prostaglandin F2 alpha (PGF2 alpha) and the relaxation response to isoprenaline (Isop), in 48 bronchi obtained from 10 patients who received surgery. Responses were measured in the presence and absence of the epithelium. 2. Removal of epithelium (by rubbing the mucosa gently with forceps) significantly increased the contractile responses evoked by ACh, histamine and PGF2 alpha. 3. In contrast, removal of epithelium did not alter the relaxation response to Isop. 4. To clarify the mechanism underlying this epithelial inhibitory effect on smooth muscle contraction, we measured the contractile responses of dog trachea with the epithelium removed to increasing concentrations of ACh. After measuring the control response, we added about 0.1 g of the chopped epithelium in the organ chamber, and measured the response again. 5. After adding airway epithelium and incubating with tracheal strips, the contractile response of tracheal strips decreased significantly as compared to the control response. 6. These results show that airway epithelium possesses the ability to decrease the smooth muscle contraction to ACh, histamine and PGF2 alpha in man and dogs. 7. The mechanism of this inhibitory effect of the airway epithelium is not explained by a change in mechanical property of the airway nor the change in diffusion of these drugs to the smooth muscle across the epithelium. Thus, these results suggest that airway epithelium may have an important role in modulating smooth muscle tone, possibly by inactivation of these mediators, or by releasing an epithelium-derived relaxing factor.

The Role of Basal Cells in Adhesion of Columnar Epithelium to Airway Basement Membrane

Abstract: In this report, we present a new concept of the role of the basal cell in airway epithelium. Previously, the basal cell was thought to be the progenitor cell for the columnar epithelium. However, several studies have shown that this concept may not be correct. The morphologic aspects of the basal cell suggest that it could play a role in adhesion of the columnar epithelium to the basement membrane. Basal cells form attachments with columnar cells (desmosomes) and with the basement membrane (hemidesmosomes). Columnar cells do not form hemidesmosome attachments with the basement membrane. Basal cells could strengthen the adhesion of columnar cells to the basement membrane by forming hemidesmosome attachments to the basement membrane and desmosome attachments with adjacent columnar cells. Incidental evidence from 2 existing publications concerning airway microanatomy support this concept. As columnar cells grow taller, the proportion of the cell surface in contact with the basement membrane becomes progressi...

The effect of bacterial products on ciliary function.

Abstract: Mucociliary clearance protects the respiratory epithelium against inhaled particles. There is in vitro evidence that some bacteria produce factors that cause ciliary slowing, dyskinesia, and stasis. These changes may predominantly affect ciliary function alone or be associated with epithelial disruption and cell death. Some factors act immediately, while others can take up to a number of days to achieve effect. It is postulated that rapidly acting factors may be involved during bacterial colonization, allowing the bacterium time (by slowing clearance) to penetrate the mucociliary barrier and reach putative receptors on the epithelial surface. The compounds might similarly facilitate contiguous spread through the bronchial tree and augment the tissue damage caused by the host inflammatory response during chronic bronchial sepsis. Future work should define more clearly the in vivo significance of the largely in vitro observations made to date.

Airway epithelium modulates the responsiveness of porcine bronchial smooth muscle.

Abstract: The effect of epithelium removal on the responses of porcine airways to exogenously applied agonists and nerve stimulation was examined. Paired rings of third- (segmental), fourth- and fifth-order (subsegmental) bronchi, with and without epithelium, were placed in organ chambers in physiological salt solution (95% O2-5% CO2, 37 degrees C). Removal of the epithelium caused a leftward shift in the concentration-effect curve for acetylcholine (3rd and 4th order). A similar shift occurred for histamine (3rd and 5th order). The relaxation to isoproterenol was reduced by epithelium removal in a similar fashion in the three orders. Removal of the epithelium reduced the maximal response to KCl (3rd and 4th order) and acetylcholine (5th order). The peak response to nerve stimulation showed a significant rightward shift in the absence of epithelium. In fifth-order bronchi, tissues with epithelium showed a significantly greater degree of fade of the response to sustained electrical stimulation. Thus both epithelium-derived relaxing and contracting factors may be released in porcine airways.

Influence of epithelium on the responsiveness of guinea-pig isolated trachea to adenosine.

Abstract: 1. The influence of epithelium removal on the effects of adenosine on airway contractility was investigated on the guinea-pig isolated trachea. 2. In preparations under resting tone or precontracted with histamine 10(-5) M, removal of the tracheal epithelium resulted in similar shifts to the left of the adenosine concentration-response curves (0.61 +/- 0.18 (P less than 0.05) and 0.80 +/- 0.09 (P less than 0.001) log units; n = 5), corresponding to 4.07 and 6.31 fold potentiations of the relaxant effect of adenosine. 3. In the presence of dipyridamole 10(-5) M the relaxant effects of adenosine were potentiated 85.1 fold on tracheae with epithelium; removal of the epithelium did not produce a significant additional shift to the left of the adenosine concentration-response curves (0.07 +/- 0.03 log units; n = 5; NS). 4. In the absence of dipyridamole, the theophylline-adenosine antagonism was not of the competitive type, irrespective of whether the tracheae were with or without epithelium. 5. In the presence of dipyridamole, this antagonism was likely to be of the competitive type and its characteristics were the same when the epithelium was present or absent. Regression slope and pA2 values were 0.84 and 5.07, respectively, in the presence of epithelium and 0.76 and 4.89, respectively, in its absence. 6. It is suggested that, at least in the guinea-pig isolated trachea model, the airway epithelium seems to be involved only in the uptake and metabolism of adenosine.

One-year inhalation toxicity study of formaldehyde in male rats with a damaged or undamaged nasal mucosa.

Abstract: To study the effect of bilateral intranasal electrocoagulation damage on the susceptibility of rats to formaldehyde vapour, male Wistar rats with a damaged or undamaged nasal mucosa were exposed to atmospheres containing 0, 0.1, 1 or 10 ppm formaldehyde vapour during 6 h/day, 5 days/wk for 13 or 52 weeks. Electrocoagulation damage was induced in the anterior third part of the nose. The repair process followed the pattern of wound healing. Loss of turbinates and perforation of the septum were common irreversible findings. After 13 weeks basal cell hyperplasia and squamous metaplasia of the respiratory epithelium, and rhinitis were still visible. After 52 weeks effects attributable to electrocoagulation were slight basal cell hyperplasia and some rhinitis. Major formaldehyde-related adverse effects in the 10 ppm group not subjected to electrocoagulation included growth retardation, reduced urine production, and rhinitis accompanied by squamous metaplasia of the nasal respiratory epithelium. No adverse effects were seen at 0.1 or 1 ppm in rats with an intact nasal mucosa. The principal untoward effects of formaldehyde in electrocoagulation-treated rats seen after 13 and/or 52 weeks comprised increase in basal cell hyperplasia, squamous metaplasia of the nasal respiratory epithelium, damage to the olfactory epithelium at 10 ppm, and focal squamous metaplasia of nasal respiratory epithelium at 0.1 and 1 ppm. Major conclusions were: (a) the rat nose damaged by electrocoagulation is more susceptible to the cytotoxic action of formaldehyde than the undamaged nose, (b) 10 ppm formaldehyde has no adverse effect on organs remote to the site of entry in rats with an undamaged nose, and (c) 1 ppm formaldehyde did not visibly affect the intact nasal epithelium.

In vivo effects of transient neutrophil influx on nasal respiratory epithelial mucosubstances. Quantitative histochemistry

Abstract: Certain inhaled toxicants are known to induce mucous hypersecretion in the respiratory epithelium This secretory change may be a direct effect of the toxicant or an indirect effect of the concomitant inflammatory response The present study was designed to determine by quantitative histochemistry whether the influx of neutrophils through the nasal respiratory epithelium would induce significant quantitative changes in the amount of intraepithelially stored mucosubstance F344/N rats were intranasally instilled with endotoxin to elicit a transient influx of neutrophils into the nasal epithelium Peak intraepithelial infiltration of neutrophils was evident 6 hours after instillation There was a concurrent quantitative decrease in stored epithelial mucosubstance at the same time after instillation Amounts of epithelial mucosubstance returned to that measured prior to neutrophil infiltration by 24 hours after instillation, when intraepithelial neutrophils were diminishing Rats in which circulating neutrophils were sequestered in the lungs and prevented from migrating into endotoxin-exposed nasal epithelium had no change in the quantity of stored mucosubstance 6 hours after instillation Therefore, it is concluded that a transepithelial migration of neutrophils elicits a transient depletion of stored mucosubstances in the nasal respiratory epithelium Whether this is due to the release of secretagogues from the migrating leukocytes or another neutrophil-related method of stimulating mucous secretion is not known

Structure of the crypt epithelium in human palatine tonsils.

Abstract: Material from human palatine tonsils from a group of 18 tonsillectomised patients aged 22 months to 8 years was studied by LM, TEM and SEM. Special attention was focused on the structure of the epithelium lining the tonsillar crypts. This is of a dynamic nature in the living organism. In contrast to the stratified squamous epithelium covering the oropharyngeal surface of the tonsil it was often reticulated and invaded by non-epithelial cells. However, it was not uniform throughout. When studied by LM and TEM, adjacent patches of epithelium varied in degree of reticularity. The reticulated epithelium was either covered by a thin layer of squamous cells, or this was disrupted in places where non-epithelial cells passed through. Hence the intact surface, as seen on the SEM, is not a reliable indication of the nature of the underlying structure of the epithelium. Small blood vessels were frequently observed in association with the reticulated epithelium. They formed numerous finger-like projections surrounded by a sleeve of subepithelial connective tissue, and also a fine capillary network within the epithelial thickness. It is proposed that such an organisation of the crypt epithelium offers favourable means for the capturing and processing of antigens by the palatine tonsils.

effects of all-trans retinol and cigarette smoke condensate on hamster tracheal epithelium in organ culture. I: A cell proliferation study

Abstract: The effects of cigarette smoke condensate (CSC) and all-trans retinol on the cell proliferative activity of vitamin A-deprived hamster tracheal epithelium have been studied in vitamin A-deficient, serum-free, hormone-supplemented medium in organ culture. In the absence of retinol, CSC induced a dose-dependent increase in labelig index (LI) during 12 days of culture. The basal cells were more sensitive to CSC exposure than non-basal cells during the first 6 to 8 culture days. However, in squamous metaplastic foci developing after culture day 6, both basal and non-basal cells in the mid-part of the epithelium were labeled. Physiological concentrations of all-trans retinol stimulated the non-basal LI and inhibited the basal cell LI. Compared with dimethylsulfoxide (DMSO), all retinol concentrations used in the present study inhibited the basal cell LI at each time point examined (4-12 days culture). Exposure of tracheal rings to retinol, either before or after exposure to CSC, or simultaneous exposure to retinol and CSC, clearly decreased the CSC-induced basal cell proliferative activity depending on the retinol concentration used. It is concluded from the present study that squamous metaplasia induced by vitamin A-deficiency or by CSC originates mainly from basal cells and that for the maintenance of these lesions, both basal and non-basal cells play a role. Furthermore, all-trans retinol inhibited CSC-induced basal cell proliferation. Chemicals/CAS: retinol, 68-26-8, 82445-97-4; Dimethyl Sulfoxide, 67-68-5; Vitamin A, 11103-57-4

Cilia-associated respiratory (CAR) bacillus infection of obese mice.

Abstract: Cilia-associated respiratory (CAR) bacillus was identified in respiratory tract lesions of obese mice dying of chronic respiratory disease. Neither Mycoplasma pulmonis nor pathogenic bacteria were isolated from cultures of the lesions at necropsy, but there was serologic and histologic evidence of respiratory virus infection. Cranial-ventral areas of lung were firm and demarcated from unaffected lung at gross examination, and rep- resentative tissue sank in water. Microscopically, there was suppurative bronchopneumonia with extensive peribronchiole lymphocyte and plasma cell proliferation. The affected bronchiole epithelium was covered with a sheet of slightly basophilic, filamentous, gram negative bacteria. Bronchioles with lesser amounts oflymphocyte accumulations contained lesser amounts of filamentous bacteria. Bronchioles without filamentous bacteria lining the respiratory epithelium lacked peribronchiole lymphocyte accumulations. There was a high correlation between CAR bacillus-positive serology and the identification of diagnostic histologic lesions. CAR bacillus was readily stained using immunohistochemical methods, and the ultrastructural features were similar to that described in rat infections. A cilia-associated respiratory (CAR) bacillus has re- cently been isolated from Sprague/Dawley (NIH) rats with chronic respiratory disease by inoculating the al- lantoic sac of chick embryos.* The rats from which CAR bacillus was originally isolated also had serologic evidence of Mycoplasma pulmonis, sendai virus, rat corona virus, and pneumonia virus of mice infection. Weanling N:NIH (SD) rats and weanling N:NIH (S) mice were subsequently experimentally inoculated in- tranasally with the isolated CAR bacillus and devel- oped histologic pulmonary lesions typical of "Chronic Respiratory Disease," with the exception that affected respiratory epithelial cells with cilia within the lesions were covered by a layer of filamentous bacteria. This exception has diagnostic significance, since similar ap- pearing bacteria have been previously reported in four strains of laboratory rats with chronic respiratory dis- ease which were also infected with sendai virus and Mycoplasma pulmonis,8 and in wild rats with "Chronic Respiratory Disease" infected with Mycoplasrna pul- monix5 The CAR bacillus was reported in one mouse, but has not otherwise been described in spontaneous diseases of mice. When mice which died of sponta- neous chronic respiratory disease during the quaran- tine period were found to be infected with CAR ba- cillus, and not Mycoplasma pulrnonis, the following study was initiated.

Toxicologic pathology of upper respiratory tract

Abstract: The basic knowledges for toxicologic pathology of the nasal cavity in rat and mouse, including methods of preparation of their tissue specimens, anatomical and histological features, spontaneous lesions, and toxic injuries induced by chemical substances are described. In our laboratory, the following three frontal _??_ection_??_ are examined regularly: i.e. at the level of the posterior edge of upper incisor teeth (level I), at the incisive papilla (level II), and at the level of the anterior edge of upper molar teeth (level III). The _??_pontaneous lesions found in F344 rat are rhinitis, eosinophilic change of epithelial cells, accumulation of foreign bodies in the nasal cavity, submucosal deposition of calcium, venous thrombosis, and respiratory epithelium metaplasia of the olfactory epithelium. Those seen in BDF I mouse are rhinitis. eosinophilic change of epithelial cells, and respiratory epithelium metaplasia of the olfactory epithelium and nasal glands. The toxic injuries of the nasal cavity caused by chemical compounds including fumigant, formaldehyde, vinyl chloride monomer, dimethylnitrosamine, and glycol ether solvent are demonstrated.

Removal of the epithelium potentiates acetylcholine in depolarizing canine bronchial smooth muscle

Abstract: Experiments were designed to determine whether the airway epithelium affects the membrane potential of the underlying smooth muscle. The effect of epithelium removal (by gentle rubbing) on the responsiveness of isolated canine bronchi was studied. Simultaneous recordings of mechanical and electrical activity were made in paired circumferential strips (with and without epithelium) of third-order bronchi. Changes in tension were recorded with a force transducer, and changes in membrane potential were measured with a microelectrode. The cell membrane potential and resting tension of the bronchial smooth muscle were stable over a 150-min period and were not affected by removal of the epithelium. In the presence of antagonists at muscarinic and adrenergic receptors, the resting tension and membrane potential were comparable in preparations with and without epithelium. By contrast, the anticholinesterase, echothiophate, caused depolarization in bronchi without epithelium. Exposure to high potassium induced similar levels of depolarization and contraction in tissues with and without epithelium. No significant differences in threshold for depolarization or for mechanical activation in the membrane potential-tension relationship were noted in the presence or absence of epithelium. In the presence of echothiophate, removal of the epithelium augmented the contraction of the bronchi to acetylcholine; the depolarization of the cell membrane induced by the cholinergic transmitter was significantly larger than in control tissues, even when matched contractions were compared. These observations indicate that the respiratory epithelium generates an inhibitory substance that dampens depolarization and contraction of bronchial smooth muscle caused by acetylcholine.

Pre-natal development of rat nasal epithelia. IV. Freeze-fracturing on apices, microvilli and primary and secondary cilia of olfactory and respiratory epithelial cells, and on olfactory axons.

Abstract: Olfactory axons and apical structures of olfactory epithelia and of nasal respiratory epithelia of rat embryos were studied with the freeze-fracture technique; adult tissue samples of the same sources were used for comparison. At the onset of epithelial differentiation (14th gestational day) intramembranous particle densities are the same for all structures in both epithelial types. During further development, particle densities in membranes of primary cilia remain lower than those in membranes of other apical structures. Otherwise, I found the following from the 14th to the 19th day of gestation.a. Olfactory receptor cells of embryos of all age groups have axons wherein the membrane particle densities are about half those of adults. These densities are always lower than those of dendritic ending structures. Dendritic endings with primary cilia have lower densities than endings with secondary cilia; densities mainly increase when the endings sprout secondary cilia. Adult values are reached at the 18th day of gestation.b. Olfactory supporting cells with only globular particles in their apices gradually transform into, or are replaced by, supporting cells which also have dumbbell-shaped particles in their apices. Particle densities are always higher in apical structures of supporting cells than in apical structures of receptor cells. Adult values are reached at the 17th day of gestation.c. Putative ciliated and ciliated respiratory epithelial cells have considerably lower particle densities in membranes of their apical structures than do olfactory epithelial cells. Of special interest is that this is also true for secondary respiratory and olfactory cilia; as soon as genesis of secondary cilia in either epithelial type begins, their membrane features differ. Also, in contrast to apical structures of the olfactory epithelium, particle densities in apical structures of the respiratory epithelium do not systematically change during pre-natal development, and resemble the density values of adults. An exception are the microvilli of the respiratory cells with secondary cilia, membranes of which have considerably higher particle densities in adults than in embryos. In conclusion: Transformations of olfactory receptor cell dendritic endings with primary cilia into endings with secondary cilia, and of olfactory supporting cells with globular particles in their apices into cells with dumbbell-shaped particles in their apices are accompanied by increases in the densities of their intramembranous particles. These developmental changes parallel the electrophysiological onset of olfactory receptor cell specificity.

Selective adhesion of mast cells to tracheal epithelial cells in vitro.

Abstract: In allergic and nonallergic lung diseases, if intraluminal mast cells adhere to airway epithelium, inflammatory mediators released from activated mast cells may reach high local concentrations and thus greatly affect airway function. To determine whether mast cells adhere to airway epithelial cells, radiolabeled or unlabeled dog mastocytoma cells were incubated with cultured dog tracheal epithelial cells, with extracellular matrix substrates, and with cryostat-cut sections of dog trachea. Mast cells adhered well to cultured epithelial cells (35 +/- 13% adhesion, mean +/- 1 SD, n = 23) but adhered poorly to types I and IV collagen or to fibronectin (less than 7.5% mean adhesion in all cases). Similarly, in tracheal tissue sections, mast cells adhered preferentially to epithelial cells in surface epithelium or in submucosal glands but not to basal membrane or connective tissue. Adhesion to cultured epithelial cells was a characteristics of a subpopulation of mast cells, could persist for more than 48 h, did not require energy or the presence of divalent cations, and was not mediated by a known family of leukocyte-associated adhesion glycoproteins. Adhesion was completely abolished by pretreatment of mast cells with pronase E or proteinase K but not with trypsin (up to 10 micrograms/ml at 37 degrees C for 20 min each). In contrast, pretreatment of cultured epithelial cells with any of these proteinases had no effect on adhesion. It is concluded that dog mastocytoma mast cells adhere to dog tracheal epithelial cells and do so selectively. It is suggested that mast cell adhesion to airway epithelium may play a role in the effectiveness of mast cell-epithelial cell interactions, and thus, in certain lung diseases, airway function may be affected by intraluminal mast cells more than is currently appreciated.