Showing papers on "Respiratory epithelium published in 1981"

Involucrin synthesis and tissue assembly by keratinocytes in natural and cultured human epithelia.

Abstract: Different stratified squamous epithelia, whether they bear a stratum corneum or not, are shown by immunofluorescence to possess the precursor protein of the cross-linked envelope that is characteristic of epidermal s. corneum. This protein, involucrin, is not present in the deepest epithelial cells but appears in the course of their outward migration. The boundary at which involucrin first appears can sometimes by correlated with a visible boundary between zones of large and small cells. Cultured keratinocytes, derived from all stratified squamous epithelia (epidermal, corneal, conjuctival, esophageal, lingual, and vaginal), form colonies that grow together to form a stratified epithelium. The cells of the basal layer are nearly always free of detectable involucrin, but, in contrast to the natural epithelium, this protein usually makes its appearance in the cells immediately above the basal layer. When a cultured epithelium derived from epidermal keratinocytes is detached and applied as a graft to animals, the cells flatten and the distinctness of the basal layer is at first reduced; but with time the organization of the epithelium becomes more characteristic of epidermis. Cell size and shape become more orderly along the cell migration pathway, and involucrin first appears at some distance from the basal layer, instead of in immediately suprabasal cells, as in the cultured epithelium. The progeny of dissociated and cultured keratinocytes are therefore able, when grafted, to reassemble an epidermis in which the timing of specific gene expression is restored to that of the original tissue.

The cells of the tracheobronchial epithelium of the mouse: a quantitative light and electron microscope study.

Abstract: The epithelium of the conducting airways of the mouse consists of a single layer of cells. The number, type and form of these cells have been investigated at five airway levels from the trachea to the distal conducting bronchi with both light and electron microscopes. Contrary to what is found in other species, the majority (50-60%) of cells in the murine airway epithelium are Clara cells. Mucus-producing tissue was infrequent throughout the airways, though epithelial mucous cells occurred in increased numbers at the carina and in the primary bronchus. No mucous or serous cells or submucosal glands were seen in intralobular airways. On a morphological basis, three distinct forms of Clara cell were recognized. On occasion, cells were observed which were apparently transitional types between these and also between Clara cells and mucous or ciliated cells. It is suggested that the 'transforming' cells may indicate a role for the Clara cell as a developmental cell involved in the epithelial cell turnover. Evidence is also provided that Clara cells may undergo both apocrine and merocrine secretion and, it is argued that the latter may be of a PAS + ve material. Free nerve endings were not seen in the epithelium. This may be related to athe restricted ability of mice to cough. It is suggested that the lack of mucus-producing tissue and of cough reflex may be due to the small diameter of the mouse airways.

The effect of tobacco smoke, with or without phenylmethyloxadiazole (PMO), on rat bronchial epithelium: a light and electron microscopic study.

Abstract: The effect of whole cigarette smoke on rat airway epithelium and of the addition of an anti-inflammatory drug, phenylmethyloxadiazole (PMO), to the tobacco, was studied in experiments extending up to 6 weeks. Two airway levels were studied, the left main extrapulmonary bronchus and a distal intrapulmonary bronchiolus. After cigarette smoke alone, the greatest change was found in the main extrapulmonary bronchus where there was an increase in epithelial thickness due to cell hypertrophy and a change in cell shape. The number of cells increased in proportion to the duration of exposure. Hyperplasia was not preceded by epithelial degeneration or necrosis. In the animals exposed to tobacco smoke alone, ciliated, mucous and basal cells increased whilst intermediate and epithelial serous cells decreased in number. The appearance of cells intermediate in structure suggests that epithelial serous cells transformed into mucous cells. The change involved an increase in secretory granule size, number and electron-lucency, the last probably reflecting a chemical alteration in the glycoprotein. In ciliated cells, mitochondria increased in length. The concentration of dividing cells increased, notably at days 1 and 7. Addition of PMO to the tobacco, 2 per cent. by weight, diminished the increase in bronchial epithelial thickness, cell size, mucous cell number and percentage of dividing cells seen after tobacco smoke alone: the shift in proportion of the various cell types was similar except that the increase in ciliated cell number was much greater than the increase seen with tobacco smoke alone.

APUD cells in teratomas.

Abstract: The origin of the endocrine cells in the respiratory tract and the gastrointestinal tract is still a matter of debate. In the original concept of the amine precursor uptake and decarboxylation (APUD) system, all APUD cells were considered to be derived from the neural crest. More recently it has been proposed that the APUD cell types of the gastrointestinal and respiratory tracts originate from neuroendocrine-programmed ectoblast. Still other investigators have reported observations that favor a direct endodermal origin of these cell types. Based on the assumption that in teratomas different tissue types which in normal embryogenesis are derived from the neuroectoderm might be expected to occur together, we investigated a series of cystic ovarian teratomas and testicular teratocarcinomas for the presence of brain tissue and of different types of APUD cells. In the ovarian teratomas, intestinal and respiratory APUD cell types were found almost exclusively without coexistence of brain tissue, whereas melanocytes, which are of neuroectodermal origin, occurred mostly together with brain tissue. In the testicular teratocarcinomas, intestinal types of APUD cells occurred without brain tissue. Peptide hormone production was found in appropriate tissues. It can therefore be concluded that in teratomas appropriate intestinal and respiratory APUD cells differentiate in and presumably descend directly from intestinal and respiratory epithelium.

Inhibition of glycoconjugate secretion by colchicine and cytochalasin B. An in vitro study of human airway.

Abstract: The effects have been analyzed of cytochalasin B and colchicine on the secretion of glycoconjugates by human bronchial expiants labeled in vitro with radioactive glucosamine. Both cytochalasin B and colchicine had no effect on baseline 14C-labeled glycoconjugate release but caused a dose-dependent (10−7–10−4 M) inhibition of 14C-glycoconjugate release and discharge of labeled macromolecules from mucous and serous cells induced by 5 · 10−5 M methacholine. Quantitative autoradiographic analyses showed that neither cytochalasin B nor colchicine inhibited 3H-threonine or 3H-glucosamine incorporation into mucous and serous cells of the submucosal glands or goblet cells of the airway epithelium. Colchicine (10−5 M) but not cytochalasin B significantly reduced the rate at which labeled macromolecules were transported through mucous, serous and goblet cells but this effect was not observed until 4 h after the addition of colchicine. Neither cytochalasin B nor colchicine affected the basal rate of labeled-macromolecule discharge from mucous, serous or goblet cells. At a concentration of 10−5 M, both agents completely inhibited the increase in labeled-macromolecule discharge induced in mucous and serous cells by methacholine. Our results suggest that in the submucosal gland of human airways microtubules and microfilaments may be important in secretagogue-induced but not in baseline cellular glycoconjugate discharge, implying that the mechanisms of the two processes differ significantly. Furthermore, a role for microtubules is suggested in the transport of secretory granules through mucous, serous and goblet cells.

Secretory component of IgA: a marker for differentiation of ocular epithelium

Abstract: Secretory component (SC) toas studied by indirect immunofluorescence of the ocular surfaceepithelium. We find that conjunctival epithelium produces this component, and that it is absentin the corneal epithelium. Conjunctival epithelium loses its SC staining within 1 to 2 days as itgrows over a denuded corneal stroma. This implies a very rapid turn-off of the SC gene andrapid export of the gene product formed. previously However, conjunctival flap epitheliumdoes not change its characteristic structure or functions. Vascidarization of corneas resurfacedby conjunctival epithelium usually leads to a rapid reversal of both morphological and bio-chemical characteristics in the surface epithelium, as judged by the reappearance of goblet cellsand positive staining for SC. Vascidarization of normal corneas leaves the epithelium un-changed, so that neither goblet cells nor SC appear. Thus metaplasia of conjunctival to cornealepithelium is incomplete, permitting reversion to type under certain conditions.Key words: secretory component, epithelial cell metaplasia,corneal vascularization, inflammation

Mitotic indices of rat laryngeal epithelia.

Abstract: The histology and mitotic indices of rat laryngeal epithelia were investigated Five distinct types of epithelia were found: stratified squamous, squamoid (low squamous), respiratory and two cuboidal forms Squamous epithelium was present mainly in the cranial portion of the larynx, whereas the respiratory type was mostly located in caudal regions One type of cuboidal epithelium often formed intermediate zones between squamous and respiratory areas Another form of cuboidal epithelium lined the ventral pouch, and the vocal folds were covered by a low squamous or squamoid type The mitotic index for each type of epithelium was calculated using colchicine and was expressed as the percentage of total epithelial cells of that kind in mitosis Mitotic indices for laryngeal epithelial types were: 56% in squamous epithelium; 24% in the squamoid epithelium of the vocal folds; 22% in the cuboidal epithelium in the ventrolateral region; 15% in the cuboidal epithelium of the ventral pouch, and 06% in respiratory epithelium, although in isolated ciliated areas in the lower epiglottis it was considerably higher (26%) There were no significant differences between rats examined on different occasions

Mitotic activity of airway epithelium after short exposure to tobacco smoke and the effect of the anti-inflammatory agent phenylmethyloxadiazole.

Abstract: Mitotic activity of extra- and intra-pulmonary airway epithelium has been studied in male rats exposed to tobacco smoke for 1, 2, 3, 7 or 14 days, with and without addition of the anti-inflammatory agent phenylmethyloxadiazole (PMO) to the tobacco. In both control and exposed animals the mitotic index is greater in extrapulmonary regions than intrapulmonary ones. A single exposure to tobacco smoke significantly increases mitotic activity in both airway regions. This initial level of mitotic response is not maintained but is rapidly restored by 1 day free from tobacco exposure: the second peak is as high as the first. Exposure to tobacco + PMO modifies timing and amplitude of the mitotic response. The effect of PMO is somewhat paradoxical since the first peak occurs later, i.e. after 2 days of exposure, but the increase is almost twice that seen after tobacco alone. The timing of the second peak is the same as after tobacco alone, but its amplitude is only half. In each experimental group the mitogenic effect is exerted on an intact epithelium. In animals exposed to tobacco alone, or tobacco + PMO, in extrapulmonary airways mitoses are located mainly in the basal region of the epithelium, whereas in intrapulmonary airways they are located mainly at the mid or superficial level.

Fine structural and enzyme histochemical observations on the respiratory epithelium of the caecilian lungs and gills. A contribution to the understanding of the evolution of the vertebrate respiratory epithelium.

Abstract: The alveolar epithelium of larval and adult caecilians is composed of one cell type only, the cytoplasm of which, however, is divided into two divisions: an organellerich part containing the nucleus and a flattened peripheral part which covers the blood capillaries. Apically the cells bear variously shaped microvilli, which are sparse on the flattened areas of the cells. Among the cytoplasmic structures electron-dense bodies and lamellated bodies are prominent. Morphological observations suggest that in the adult the lamellated bodies are derived from the dense ones, which presumably represent lysosomes. Acid phosphatase and unspecific esterase are present in the entire alveolar epithelium. The lamellar material is extruded by exocytosis. A close structural relation between lamellated bodies and multivesicular bodies-as to be found in many mammalsdoes not exist. In the larvae among others there exists an extensive lateral labyrinth between neighboring alveolar cells and a considerable variability of the lamellated bodies. The latter frequently arise within or near fields of glycogen or presumably also within membrane systems.

Hemadsorption and virulence of Mycoplasma pneumoniae.

Abstract: Mycoplasma pneumoniae is a prokaryotic respiratory tract pathogen of man which causes cold agglutinin-associated primary atypical pneumonia. Although relatively little is known about the properties of this organism that endow it with pathogenicity for man, the use of a hamster model system established that the ability of M. pneumoniae to adhere to respiratory tract epithelium is a critical virulence determinant for this pathogen (1,2). Virulent strains of M. pneumoniae, in addition to being capable of adhering to respiratory epithelium, also form colonies on solidified growth medium that readily adsorb erythrocytes of many different species, in a process called hemadsorption (3). It has been established that trypsin treatment of virulent M. pneumoniae colonies eliminated the hemadsorption ability of these colonies (4). Previous studies from our own laboratory have established that trypsin-sensitive proteinaceous structures on the external membrane surface of virulent strain cells of M. pneumoniae are involved in the attachment of this parasite to host respiratory epithelium (5). It has been shown further that a homologous avirulent strain of M. pneumoniae that does not attach to respiratory epithelium in vitro also forms hemadsorption-negative colonies (6). All of these data taken together suggested that M. pneumoniae might utilize the same mechanism(s) for both hemadsorption and attachment to respiratory epithelium. In order to evaluate the relationship of the hemadsorption process to both respiratory epithelium attachment capability and virulence of M. pneumoniae, we employed a mutant analysis approach in conjunction with a hamster model system.

Transition between columnar absorptive cells and goblet cells in the rat jejunal epithelium.

Abstract: Electron microscopic observation of the jejunal epithelium of rats demonstrated morphological evidence of a transition between columnar absorptive cells and growing goblet cells. The columnar cells in both the villi and crypts have features suggestive of absorptive functions. They are provided with apical invaginations continuous to the intermicrovillous space. Absorbed lipid is observed in small vesicles in the terminal web layer, and chylomicrons derived here from are contained in large vacuoles near the Golgi apparatus. Ferritin particles artificially infused into the gut lumen were absorbed into the vacuoles in the subapical zone of columnar cells of suckling rats. Growing goblet cells situated in the crypt epithelium contain surface invaginations and lysosomes which are the same in structure as those found in absorptive cells nearby. Fat droplets evidently absorbed by the growing goblet cell were observed among immature mucus droplets. Artificially infused ferritin particles were found in vacuoles and lysosomes near the Golgi apparatus of some goblet cells of suckling rats. Some goblet cells on the intestinal villi of suckling rats looked immature and their microvilli and cytoplasmic matrix were clear like those of columnar absorptive cells. The transition between these goblet cells with clear cytoplasm and the mature goblet cells with dark cytoplasm was observed. These morphological evidences indicate that some of columnar cells already differentiated to absorptive cells are capable of transforming into mucus-producing (goblet) cells. It is suggested that not only undifferentiated columnar cells in the crypt base but also considerably differentiated columnar cells with absorptive function can differentiate into goblet cells.

Effects of serotonin on ion transport in intestinal and respiratory epithelium

Abstract: The potassium-sparing diuretic amiloride is a potent and reversible inhibitor of electrogenic absorption by epithelia in many species. Amiloride appears to be a specific inhibitor of the sodium-transportor of the luminal plasma membrane. Physiological compounds that inhibit electrogenic sodium absorption in vivo at the same site and act as rapidly as amiloride have not yet been identified. Indoleamines were tested as inhibitors because they are produced in relatively high concentrations by epithelial endocrine ( APUD) cells and are structurally similar to amiloride. Firstto third-order bronchi from male baboons and the descending colon from Sprague-Dawley rats were maintained in Krebs-Henseleit solution containing 5 mM glucose and was gassed with 5% carbon dioxide in oxygen. Electrogenic ion transport was estimated from the short-circuit measured in vitro with the tissue mounted in Frizzell-Schultz chambers and measuring the current with a four-electrode voltage clamp. Amiloride and freshly prepared solutions of indoleamines were added to the luminal side of the tissue. The baboon bronchial epithelium generates a short-circuit current of 43 pA/cm2 (PD = 3.9 mV, R = 88 a cm2, from 12 animals) with 63% of the short-circuit current being inhibitable by 25 pM amiloride. The colonic epithelium from sodium-deprived rats generates a short-circuit current of 422 pA/cmz (PD = 22.1 mV, R = 66 cm2, from 12 animals) with 95% of the short-circuit current amiloride-sensitive. Serotonin, harmaline, and melatonin inhibit the short-circuit current similar to amiloride with (1) an onset of inhibition in seconds, (2) the inhibition was seen from the luminal surface only, (3) the inhibition was reversible, and (4) these compounds inhibited only that portion of the short-circuit current that was amiloride-sensitive. The concentration of half-maximal inhibition for serotonin in the baboon bronchi was 0.35 mM and 12 mM in the rat colon. Many investigators have shown that the amiloride-sensitive short-circuit current is an electrical manifestation of sodium absorption from the lumen of epithelia (i.e. by correlating electrical and sodium ion fluxes and by localizing of amiloride-sensitive sodium conductance to the luminal membrane). The amiloride-sensitive short-circuit current of our preparations is equivalent to sodium absorption since: (1 ) the short-circuit current is largely dependent on the presence of luminal sodium; (2) no amiloride-sensitive current is seen in the absence of luminal sodium; and ( 3 ) with incremental increases in the luminal sodium concentration, the increments in short-circuit current are inhibitable by amiloride. This amiloride-sensitive sodium absorption appears to be specifically inhibited by serotonin and other indoleamines in that: (1) the maximal inhibition with serotonin and amiloride is similar, suggesting a single site of action; (2) inhibition is seen only from the luminal bath; (3 )

Kinetics of sulfated mucous glycoprotein secretion in dog trachea in vitro

Abstract: Previous studies on mucous glycoprotein secretion in respiratory epithelium most often provided qualitative, rather than quantitative, data. This study describes a new technique to measure the secretion rate, pool size, and turnover time of the pool of sulfated mucous glycoproteins of dog tracheal epithelium. The technique involved interposing dissected tracheal epithelium between the halves of an Ussing-type chamber, incubating the submucosal side of the tissue with 35SO4, and measuring the rate of appearance of nondialyzable 35SO4 on the luminal side of the chamber of both during the labeling and "washout" of the mucous pool. By analyzing the pattern of elimination, we showed that 1) a steady secretion rate of labeled mucous glycoprotein occurs within 3-4 h when free 35 SO4 is present on te submucosal side of the tissue, 2) secretion is consistent with first-order kinetics from a single pool, 3) puromycin decreases the rate of secretion of labeled mucous glycoprotein, 4) secretion rate is greater in medium 199 than in modified Krebs-Henseleit solution, and 5) 1.2 mM SO4 supports maximal baseline secretion. In six tracheas, bathed in Krebs-Henseleit solution, the secretion rate was (mean +/- SE) 467 +/- 74 pmol SO4 x cm-2 x h-1, pool size, 964 +/- 144 pmol SO4/cm2, and turnover time, 2.12 +/- 0.16 h. This technique provides a quantitative method to characterize kinetics of sulfated mucous glycoprotein secretion.

[Use of histological methods for the demonstration of the anti-inflammatory activity of fusafungin (author's transl)].

Abstract: The anti-inflammatory activity of fusafungin may be demonstrated in guinea-pig, with use of morphological methods. Indeed, edema and congestion of the lamina propria of the trachea, break of cilia of the respiratory epithelium, which are witness of inflammation induced by acrolein, do not appear after treatment by fusafungin. However, the cellular phenomenons of inflammation do persist.

Scanning electron microscopical investigations on the respiratory epithelium of the Syrian golden hamster III. Regeneration after traumatic injury.

Abstract: To investigate the extent to which intratracheal intubation may alter the respiratory epithelium of the Syrian golden hamsters, single and repeated intubations were undertaken and the resulting injury and subsequent epithelial regeneration were examined by scanning electron microscopy. Generally, epithelial injury as a result of a single intubation had healed ad integrum within 20 to 40 days. On the other hand, repeated treatment often caused tracheitis and led to prolonged regeneration which sometimes persisted as papillary hyperplasia 40 days after the final intubation. The appropriateness of intratracheal instillation as a method of administering chemical carcinogens and the similarity of the epithelial regeneration processes to early neoplastic alterations of the epithelium are discussed.