Showing papers on "Respiratory epithelium published in 1979"

Differential permeability of endothelial and epithelial barriers to albumin flux

Abstract: We measured the flux of albumin between the vascular space and the pulmonary interstitial and luminal lining fluids in 20 adult sheep with chronic lung lymph fistulas. We sampled the bronchoalveolar lining layer by episodic fiberbronchoscopic lavage. A total of 62 alveolar lavages were performed at times ranging between 30 min and 60 h after intra-arterial injection of 100 microCi of 125I-labeled albumin. Samples of lymph and plasma were obtained simultaneously with lavage fluid, and the radioactivity and albumin content of all samples were measured and expressed as specific activity (counts/min . g albumin). We found that alveolar lavage fluid collected by our technique is not significantly contaminated by plasma or interstitial fluid proteins. Proteins present in alveolar lavage fluid and also present in plasma reach the alveolar space by a normal diffusive process, and not as a result of epithelial membrane damage occurring at the time of lavage. Lung epithelial permeability to albumin in small, but finite (4.3--5.8 x 10(-10) cm/s). Virtually all (greater than 92%) of resistance to albumin flux across the alveolocapillary membrane lies in the epithelial barrier. Increases in permeability of the respiratory epithelium, even minor, would have a marked effect on water and solute balance in the lung. Epithelial injury will potentiate pulmonary edema formation even in the presence of normal pulmonary microvascular pressure, plasma oncotic pressure, and endothelial permeability.

Control of mucus secretion and ion transport in airways

Abstract: The output of secretions from the airway submucosal glands is regulated by vagal efferent nerves. Stimulation of cough receptors increases mucus output reflexly via the vagus nerves. Adrenergic agonists increase submucosal gland secretions in some species, which indicates that adrenergic receptors are present in these cells. However, evidence for adrenergic nervous pathways to the glands is limited. Irritants and drugs stimulate secretion from epithelial cells by direct effects. There is also evidence that the secretion of epithelial cells can be stimulated by parasympathetic nervous pathways in birds but not in mammals. Active ion transport of Cl- toward the lumen and of Na+ toward the submucosa results in net ion movement toward the airway lumen in unstimulated tracheal epithelia. Drugs and mediators increase the net movement of ions toward the lumen. No agents have yet been found that increase net ion movement toward the submucosa. The link between ion transport and water secretion in airway epithelia, although speculative, seems likely in view of the evidence from other epithelia. Since airway epithelium is a "tight junction" epithelium, modification of the tight junction may alter the transepithelial movement of water and ions. We suggest that the depth and consistency of the periciliary layer of airway secretions determine the ability of the cilia to propel the mucoprotein gel and thereby modify mucociliary transport. To achieve this, secretion of mucus must be controlled separately from the secretion of water. Studies are needed to determine which of the specialized functions of the epithelial cells interact to regulate the clearance of secretions from the airway. Is the sol maintained by secretion and reabsorption of fluid across the epithelium? Does the sol move with the gel by ciliary action or does it remain stationary? Do changes in the epithelial tight junctions influence net water movement and thus indirectly alter the depth of the sol layer? To answer these questions, techniques are needed to study subunits of the airway, including isolated surface cells and submucosal glands; and sensitive methods are required to analyze the very small samples of secretions for glycoprotein and electrolyte content. Intracellular measurements of electrolyte concentrations and electrical potentials may help to elucidate the mechanisms of transepithelial ion and water movement. The control system for the production and removal of respiratory tract secretions may be altered in disease. For instance, chronic stimulation of cough receptors causes reflex secretion and may be the cause of the hyperplasia of submucosal glands and of the abnormal secretions that occur in chronic bronchitis and asthma (50, 58). The abnormally viscid mucus in cystic fibrosis may be due to a defect in Cl- transport, which provides too little water for both the gel and sol layers. These speculations are intended to identify areas for further research, which hopefully will reduce the morbidity and mortality in these common lung diseases.

The Respiratory Epithelium. VII. Epidermoid Metaplasia of Hamster Tracheal Epithelium During Regeneration Following Mechanical Injury

Abstract: Regeneration was studied in female Syrian golden hamster tracheal epithelium. The epithelium was focally removed in vivo by scraping it with a blunt probe. At 2 hours, virtually all cells had sloughed from the injured area leaving a bare basal lamina. At 6 and 12 hours, flattened cells that migrated from adjacent uninjured epithelium partially covered the denuded basal lamina. Increased cell division did not occur at these times. Many of the simple squamous cells contained well-developed endoplasmic reticulum, Golgi apparatus, and mucous granules. Other cells resembled basal cells. At 24 hours the defect was covered by one or two layers of simple squamous cells. At that time, many of those cells were in division, and cell division was also greatly increased in mucous cells and basal cells in the uninjured epithelium distant from the defect. At 48 hours the epithelium was stratified, composed of four or five layers of polygonal to flattened cells, typical of nonkeratinizing epidermoid metaplasia. The cells contained many tonofilament bundles, a large Golgi apparatus, and many tiny mucous granules. Mitoses were seen in all cell layers. At 72 hours, the surface layer of cells was undifferentiated (indifferent cells) overlying an epithelium that otherwise retained its epidermoid character. Indifferent cells were characterized by an electron-lucent cytoplasm and a lack of tonofilament bundles, mucous granules, or cilla. Cells similar in other respects to indifferent cells were seen that possessed mucous granules or early signs of cilla formation. Some cells showed mucous granules and cilla developing in the same cell. By 96 hours, the regenerated epithelium was fully differentiated and was indistinguishable from the normal epithelium. These observations show that mucous cells have a significant role in the regenerative response. Mucous cells have a dual potential; they can undergo epidermoid metaplasia and still retain the ability to secrete mucus. The study explains the universal occurrence of mucosubstances in areas of epidermoid metaplasia and makes more understandable the previously reported fact that many bronchogenic carcinomas are combined epidermoid and adenocarcinomas. In the presence of a carcinogen, the hypothesis has been forwarded that initiation of mucous cells and basal cells occurs, which leads to malignant transformation and produces tumors that show active secretory activity and keratinization, often in the same cell.

Beta-agonists and secretory cell number and intracellular glycoproteins in airway epithelium. The effect of isoproterenol and salbutamol.

Abstract: This study describes the effect of systemic administration of the beta-adrenergic agonists isoproterenol and salbutamol on the secretory cell populations in seven regions of rat airway epithelium (three extrapulmonary and four intrapulmonary) and on the size of salivary glands and heart Isoproterenol (a nonselective beta-adrenergic agonist) significantly increases secretory cell number in all airway regions except the midtrachea; salbutamol (a selective beta 2 agonist) increases secretory cell number only in proximal and peripheral regions The absolute number of secretory cells is greatest in the most peripheral region after isoproterenol administration and in the most proximal region after salbutamol, although both drugs produce the greatest relative increase at the periphery In proximal and, particularly, peripheral regions, the increase by isoproterenol (less than 3- and 14-fold, respectively) is greater than by salbutamol (less than 2- and less than 3-fold, respectively) In all airway regions, both drugs modify intracellular glycoprotein in the secretory cell population; within a given region, modification is much the same In the most proximal region, the population of cells synthesizing only granules of neutral glycoprotein significantly increases while in other regions increase is in cells synthesizing only granules of acid A significant shift in glycoprotein synthesis occurs whether or not the secretory cell population is increased, which suggests that existing as well as newly appearing cells modify their product Isoproterenol significantly increases the size of the parotid and submaxillary glands; salbutamol increases the size of the parotid only Isoproterenol significantly increases the weight of both ventricles of the heart; salbutamol has no such effect

Comparative metabolism of benzo(a)pyrene in organ and cell cultures derived from rat tracheas.

Abstract: Primary cultures from tracheal explants and a nontumorigenic tracheal epithelial cell line (2Cl), derived from 12- O -tetradecanoylphorbol-13-acetate-exposed tracheal explants, metabolized benzo( a )pyrene to qualitatively similar organic solvent-soluble and water-soluble metabolites. Similar metabolites were formed by short-term organ cultures of tracheas. In contrast, a tumorigenic tracheal epithelial cell line (1000 W) did not metabolize benzo( a )pyrene to any significant extent. The major metabolites formed by these different tracheal systems were 9,10-dihydro-9,10-dihydroxybenzo( a )pyrene with smaller amounts, mainly as their glucuronide conjugates, of 7,8-dihydro-7,8-dihydroxybenzo( a )pyrene, 3-hydroxybenzo( a )pyrene, and 9-hydroxybenzo( a )pyrene. The higher formation of dihydrodiols, precursors of highly reactive diolepoxides, relative to monohydroxybenzo( a )pyrenes, together with low rates of detoxification of the dihydrodiols by conjugation, may in part explain the high susceptibility of the trachea to carcinogenesis. This study indicates that nontumorigenic respiratory epithelium at different levels of organization possesses similar activating and detoxifying enzymes. Since it is the balance of these oxidative and conjugating enzymes which determines how much of a metabolite is available for reaction with critical cellular macromolecules, these systems appear to be suitable for metabolic studies of factors affecting initiation and transformation of respiratory tract epithelium.

The response of rat bronchus-associated lymphoid tissue to local antigenic challenge.

Abstract: Single doses of antigen suspension (alum-precipitated canine serum proteins) were administered intratracheally to SPF rats. After periods of 1, 2 and 3 weeks rats were killed and their lungs examined histologically. After an initial macrophage and perivascular lymphoid reaction, dose-related increases were found in the amount of bronchus-associated lymphoid tissue (BALT) and in the amount of DNA within BALT cells, indicating increased cell division. Immunoglobulin-containing cells were demonstrated within BALT 3 weeks after the exposure to antigen. A prominent and extensive bronchial lympho-epithelium was seen overlying BALT follicles in antigen-treated rats, while in control animals the respiratory epithelium overlying BALT was predominantly normal ciliated epithelium. The significance of these findings is discussed in the light of the possible defensive role of BALT in cases of respiratory disease of man and animals.

Differentiation in normal human buccal mucosa epithelium.

Abstract: The epithelium of normal human buccal mucosa was studied by light and electron microscopy and stereological procedures in twenty punch biopsies of 10-15 years old females. Morphometric point counting techniques were employed in order to estimate the density of cell membranes in the superficial third of this epithelium. Observations and data suggested that (1) there is a dense and regular papillary body of slender connective tissue papillae which bifurcate within and penetrate the basal two thirds of the epithelium; (2) the epithelium comprises two major cell compartments, namely (a) the formative and proliferating basal and suprabasal cells, and (b) the differentiated but maturing spinous, and the subsurface and surface cells; (3) the major step in differentiation occurs at the boundary between suprabasal and lower spinous cells; (4) cytoplasmic composition is a reliable indicator of differentiation, which occurs prior to cell flattening; and the relative density of filamentous networks is an indicator of maturation; while cell flattening may be the sign of adaptation to functional needs, i.e. distensibility.

The effects of ozone on the respiratory epithelium of mice II: ultrastructural alterations

Abstract: Ultrastructural alterations in the tracheal and bronchial epithelium of mice exposed to 0.8 ppm ozone for varying periods of time were examined with scanning electron microscopy. The lesions were apparent in the ciliated cells. Examination of tissue from control mice showed that the ciliated cells were arranged in groups and the cilia were uniform in length. After six days of exposure to ozone, shortened cilia were occasionally observed; by day 10, more pronounced changes were observed. Cilia were either absent or became short and blunt. The lesions observed after 20 days in ozone were similar to those seen on day 10. After ozone-exposed mice had been returned to ambient air for 10 days, ciliary regeneration occurred and, the major airways had a surface appearance approaching the normal state.

Proliferation of lung and airway cells induced by nitrogen dioxide

Abstract: Proliferation of lung cells of Chinese hamsters was examined in several regions of the lung parenchyma and ciliated airway epithelium after a 24-h exposure to 282 mg/m3 (15 ppm) nitrogen dioxide (NO2) Label was retained 3 wk after the injection of [3H]thymidine, and autoradiographic methods were used to localize the site of retention By 24 h after administration of [3H]thymidine, parenchymal areas, exclusive of airways, showed an increased labeling index, indicative of cell death and replacement This increase in the number of labeled cells persisted for 3 wk Type II cells were labeled twice as frequently in regions of the terminal bronchiole than in other alveolar areas Type II cell cycle time was reduced from 26 to 3 d after NO2 exposure Alveolar macrophages were significantly labeled in the alveolar areas during the thymidine pulse at the end of the exposure episode and retained label for 3 wk Airway epithelia showed no labeling in the trachea and progressively greater labeling in increasingly small er airways Epithelial cells lining the small airways and alveoli showed greater susceptibility to NO2 injury than cells lining the bronchi or trachea Nonciliated or basal cells serve as a precursor of ciliated cells in the epithelium of small airways (035 mm) and bronchi

An electron microscope study of the respiratory epithelium in the lungs of the fire salamander (Salamandra salamandra).

Abstract: The respiratory epithelium in the lungs of the common fire salamander (Salamandra salamandra) has been studied by electron microscopy. The entire pulmonary gas-exchange area is covered by a continuous epithelium, the cells of which are all of the same type and are termed 'pneumonocytes'. Typically, each pneumonocyte is squamous and has attenuated sheets of cytoplasm which extend over the pulmonary capillaries. Its free surface bears squat microvilli, and osmiophilic inclusion bodies and other organelles are prominent in the cytoplasm. The lateral cell walls have numerous desmosomes and interdigitating cytoplasmic processes. Many cells send cytoplasmic processes deep into the substance of the lung septa. The morphological evidence suggests that the pneumonocytes are responsible for the secretion of pulmonary surface-active agents and for maintaining the integrity of the gaseous diffusion membrane.

Fine structure of cell types in an ameloblastoma.

Abstract: . An unusually large and old ameloblastoma, which revealed a diverse histological appearance, was studied by light and electron microscopy. In the tumor, the epithelial component formed several patterns in the collagenous stroma. The epithelial islands, consisting of tall columnar cells surrounding the inner core of stellate cells, mimicked the cells of the inner enamel epithelium and stellate reticulum, respectively, of the normal enamel organ. The ultrastructural appearances of the columnar cells, however, were only similar to those which are seen in undifferentiated preameloblasts. Areas of squamous metaplasia were present, and these squamous cells were structurally similar to the cells al the base of the oral epithelium. Some epithelial cells containing numerous lipid granules and mitochondria formed a network of cords. The connective tissue stroma was made up of fibroblast-like cells which appear to be metabolically active. In addition, multinucleated giant cells were present in the connective tissue stroma near the epithelial component.

Human vaginal epithelial multilayer tissue culture.

Abstract: Fragments of normal human adult vagina, when explanted onto glass slides gave rise to outgrowing sheets of pure epithelium, which had microscopic morphological features in common with normal vaginal epithelium. Infrequent fibroblast contamination was observed. Proliferating epithelial cells formedmultilayers of stratified squamous epithelium and demonstrated a progressive decrease in proliferative activity after 14 days. Continuous lines of epithelial cells were not obtained. Even in the absence of estrogens, transmission electron microscopy revealed evidence of keratinization of the superficial cells of the multilayer. Scanning electron microscopy of the surface of mature epithelial cells in culture revealed ultrastructural features that closely resembled those present on the surface of exfoliated cells obtained by scraping the vagina in vivo. This in vitro tissue culture model of human vaginal epithelium may provide a simple method of studying factors that influence vaginal epithelium growth, maturation and function.

Effect of Environmental Co2, O2 and Ph on the Growth of Respiratory Epithelium in Vitro

Abstract: Explants of rabbit tracheal epithelium were exposed to various CO2 and O2 levels and to different pH values for two weeks in organ culture. During culture the original explanted epithelium gradually changed from pseudostratified to stratified and there was a decrease in goblet cell density, and in the amount of PAS positive material in these cells. The changes in stratification were found to be independent of the pH of the medium or the CO2 level, but the proportions of ciliated cells and goblet cells were affected by the CO2/O2 ratio and by pH. Coordinated ciliary activity was preserved in most explants except for those cultured at high (80 and 95%) oxygen levels. A new growth of epithelium gradually covered the exposed connective tissue. This new epithelial growth developed the phenotypic expression of the original tissue; it gradually differentiated into ciliated cells and goblet cells. At increased CO2 levels and a high pH (7.7), differentiation into goblet cells increased fourfold, while differentiat...

Effects of cigarette smoke residue on rabbit tracheal epithelium in organ culture.

Abstract: The effects of tobacco cigarette smoke residues on rings of rabbit tracheal epithelium in organ culture were examined. Residue from cigarette smoke was collected through continuous suction and the residue from one cigarette was used for each two tracheal rings. Epithelium exposed to residue showed cellular desquamation, initially of only scattered columnar cells. As exposure time increased the entire columnar cell layer was lost, resulting in exposure of basal cells to residue. Columnar cell loss occurred through breakdown of intercellular junctions. Alteration was also observed in columnar cell mitochondria, cilia, and microvilli. Loss of columnar cells and subsequent exposure of basal cells to tobacco smoke residue may account for the hyperplasia and metaplasia observed by other investigators after long-term in vivo exposure of tracheal epithelium to cigarette smoke.

Experimental Surgery on the Nose. Changes of the Epithelium in the Vestibular Region at Altered Airflow

Abstract: In 20 rabbits one nostril was closed surgically and the nasal mucosa lying anteriorly in the vestibule was studied 4--90 days postoperatively. On the occluded side, without air-flow, the epithelium--which at this site is normally thickened due to hyperplasia of basal cells--gradually returned to a normal thinner, regular epithelium with increased number of goblet cells. On the patent side, where the airflow was doubled, the cilia were damaged. As early as the 4th day, a process of repair had been initiated, with hyperplasia of basal cells and differentiation of these cells into ciliated and goblet cells. As a result of continued trauma, similar processes continued, but there were no signs of a permanent transformation of the epithelium into squamous epithelium, not even on the 90th day.

Diurnal Variation of Deoxyribonucleic Acid Synthesis in Murine Alveolar Wall Cells and Airway Epithelial Cells1

Abstract: Diurnal variation of deoxyribonucleic acid (DNA) synthesis in cells of the alveolar wall and intrapulmonary airway epithelium of neonatal mice has been studied by autoradiography for the 3 weeks af...

[Experimental heterograft tracheal transplants in animals. II (author's transl)].

Abstract: In sequence with an earlier publication on the results of heterograft tracheal transplants in animals, changes in the Formol-Cialit preserved heterogenous tracheal grafts were studied by light microscopy, and by scanning and transmission electron microscopy. Two main queries arise. Where does the graft respiratory epithelium come from, and what happens to the grafted tracheal cartilage? We found that in the epithelium of graft the number of ciliated cells decreased and that there was ultrastructure evidence of cilial destruction, the goblet cells increased in number, there was a loss of strict polarity of the respiratory epithelium, subepithelial accumulations of cells of probable epithelial origin appeared, and there was a subepithelial accumulation of lymphocytes just beneath the basal lamina. Resorption and transformation of the grafted tracheal cartilage into connective tissue was also observed. Hence, the following conclusions may be made. (1) Small tracheal defects can be corrected by Formol-Cialit preserved heterologous grafts. (2) The mucosa of the host trachea produces a functioning respiratory epithelium in the graft. (3) Tracheal grafts should not exceed 2 x 3 cm in size otherwise a new stenosis from resorption and transformation of grafted cartilage into connective tissue will occur.

The effect of mechanical loading on the clear cells of the oral epithelium.

Abstract: Clear" or dendritic cells are found at various levels in the epithelium and are most numerous in keratinized epithelium (Hutchens, et al., J Invest Derm 1951:56:325-336). They consist of a variety of cell types such as Langerhans cells, Merkel cells and Melanocytes. Lymphocytes may also have the appearance of "clear" cells. When the oral epithelium is subjected to mechanical loading, the morphology of the individual cells is significantly altered (Stroud, M.S. Thesis, Univ. of Washington 1967, Scapino, J Morphol 1967: 122:89-114 and Fleisch and Austin, J Prosthet Dent 1978:39:211-216). 3he purpose of this study was to observe the effects of mechanical loading on the "clear" cells of the oral epithelium. Sixteen adult Vervet monkeys (Cercopithecus aethiops) were selected post-surgically from nephrectomized animals. A standardized load of 50 gms was applied to the hard palate, cheek, tongue and alveolar mucosa. The animals were decapitated, and the heads with the apparatus attached were completely immersed in 10% neutral buffered formol saline. All the procedures were completed within two minutes (Fleisch and Austin, J Prosthet Dent 1978:39:211 216). The load was applied for five days while the tissues were immersed in formol saline. Blocks of tissue containing the stressed areas were removed, processed and stained with haematoxylin and eosin for viewing with a light microscope. In normal unloaded tissue, clear cells were seen in all four regions examined. They occurred mainly in the basal and spinous cell layers and were most numerous in the tongue epithelium and least in the cheek. They did not conform in shape and size with the adjacent epithelial cells and varied considerably in size (Fig. 1). It was not possible, with the technique used, to differentiate between the three types of clear cells which have been described, namely, Melanocytes, Langerhans cells and Merkel cells. In the loaded tissue, the