Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EPITHELIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1998

Glycoconjugate secretion in human airways in vitro: effects of epithelium removal.

The aim of this study was to examine glycoconjugate secretion in human airways with and without an epithelium. Glycoconjugate release in supernatants derived from human airways in vitro was determined using an ELISA assay with an anti-human mucin monoclonal antibody (MAb 3D3). This monoclonal antibody reacted strongly with Le(b) antigen but also recognized in vitro Le(a) and Le(y) determinants. In 11 of the 34 different lung samples (32%) studied the glycoconjugate levels were below the threshhold of detection for this assay. The mean basal secretion of glycoconjugates in human airways in vitro was 100+/-28 microg/g tissue (Period I; n = 23 different lung samples). The amount of glycoconjugate measured in the medium derived from human isolated bronchial ring preparations did not change under control conditions during the course of the experimental procedure (Period I; 128+/-46 microg/g tissue and Period II; 159 +/-48 microg/g tissue; n = 13 paired lung samples). In the supernatants of airway preparations with an intact epithelium the amount of glycoconjugates detected was 90+/-38 microg/g tissue (Period I; n = 12 different lung samples) and removal of the epithelium did not alter this basal glycoconjugate release (94+/-60 microg/g tissue: Period I, n = 8 different lung samples). The absence of the epithelial layer was confirmed by histological evaluation. Methacholine (100 microM) induced a 10- and four-fold increase in glycoconjugate release from airways with and without an epithelium, respectively. In contrast, in preparations with an epithelium, LTD4 (10 microM) and anti-IgE (dilution: 1/1000) did not cause an increase of glycoconjugate release. The methacholine difference between airways with and without an epithelium was not significantly different (P > 0.10). However, a treatment with atropine (100 microM) prevented the increase of glycoconjugate release in preparations with an epithelium. These data derived from a limited number of experiments suggest that the epithelium may not regulate the basal or stimulated release of glycoconjugates from isolated human airways.

Epithelium↗
PubMed2004

Extracellular matrix: recent advances on its role in junction dynamics in the seminiferous epithelium during spermatogenesis.

Spermatogenesis takes place in the seminiferous epithelium of the mammalian testis in which one type A1 spermatogonium (diploid, 2n) gives rise to 256 spermatids (haploid, 1n). To accomplish this, developing germ cells, such as preleptotene and leptotene spermatocytes, residing in the basal compartment of the seminiferous epithelium must traverse the blood-testis barrier (BTB) entering into the adluminal compartment for further development into round, elongating, and elongate spermatids. Recent studies have shown that the basement membrane in the testis (a modified form of extracellular matrix, ECM) is important to the event of germ cell movement across the BTB because proteins in the ECM were shown to regulate BTB dynamics via the interactions between collagens, proteases, and protease inhibitors, possibly under the regulation of cytokines. While these findings are intriguing, they are not entirely unexpected. For one, the basement membrane in the testis is intimately associated with the BTB, which represents the basolateral region of Sertoli cells. Also, Sertoli cell tight junctions (TJs) that constitute the BTB are present side-by-side with cell-cell actin-based adherens junctions (AJ, such as basal ectoplasmic specialization [ES]) and intermediate filament-based desmosome-like junctions. As such, the relative morphological layout between TJs, AJs, and desmosome-like junctions in the seminiferous epithelium is in sharp contrast to other epithelia where TJs are located at the apical portion of an epithelium or endothelium, furthest away from ECM, to be followed by AJs and desmosomes, which in turn constitute the junctional complex. For another, anchoring junctions between a cell epithelium and ECM found in multiple tissues, also known as focal contacts (or focal adhesion complex, FAC, an actin-based cell-matrix anchoring junction type), are the most efficient junction type that permits rapid junction restructuring to accommodate cell movement. It is therefore physiologically plausible, and perhaps essential, that the testis is using some components of the focal contacts to regulate rapid restructuring of AJs between Sertoli and germ cells when germ cells traverse the seminiferous epithelium. Indeed, recent findings have shown that the apical ES, a testis-specific AJ type in the seminiferous epithelium, is equipped with proteins of FAC to regulate its restructuring. In this review, we provide a timely update on this exciting yet rapidly developing field regarding how the homeostasis of basement membrane in the tunica propria regulates BTB dynamics and spermatogenesis in the testis, as well as a critical review on the molecular architecture and the regulation of ES in the seminiferous epithelium.

Animals↗
PubMed2000

Renewal of the rabbit corneal epithelium as investigated by autoradiography after intravitreal injection of 3H-thymidine.

PURPOSE: To evaluate the renewal time of the rabbit corneal epithelium and to verify whether there are differences in the rate of renewal related to the topography of the cornea. METHODS: After the intravitreal injection of 20 microBq/eye of 3H-thymidine (3H-TdR), the rabbits were killed at variable survival-time intervals (3 hours to 90 days), and their corneas were processed for autoradiography on paraffin and 0.75-microm-thick Epon sections. The frequency of labeled nuclei, per each linear millimeter of epithelium, was estimated on paraffin sections of the whole length of the cornea of rabbits killed 6 hours after injection. The activity of unbound 3H-TdR was measured in the vitreous and aqueous humor. RESULTS: The incorporation of 3H-TdR into newly synthesized DNA ceased between 1 and 2 days after the intravitreal injection. At the shortest time intervals (3 hours to 1 day), the overwhelming majority of the labeled nuclei were located in the basal stratum of the stratified squamous epithelium. Cells of the wing stratum were labeled from 3 days onward. At 14 days, labeled nuclei were visualized only in the inner portion of the surface stratum, whereas their outermost layers were labeled only at 21 days and later. Lightly labeled nuclei could still be detected in the epithelium < or = 90 days after injection. The counts of labeled nuclei did not show significant differences in their frequencies between the periphery and the center of the cornea. The existence of vascularization at the periphery of the corneal stroma and the lack of a conspicuous Bowman's layer made it difficult to characterize morphologically the rabbit limbus with the light microscope. CONCLUSION: It takes >14 days for a daughter cell to migrate from the basal stratum to the outermost layer of the epithelium. Labeled daughter cells were detected < or = 90 days in several layers of the corneal epithelium. Therefore it takes >2 weeks for the complete renewal of the epithelium. Our data suggest that the proliferative capability of the centrally located basal cells is enough to guarantee the renewal of the corneal epithelium under physiologic conditions.

Animals↗
PubMed1991

Argyrophilic cells and ectocervical epithelium.

The purpose of this study was to determine the nature of the argyrophilic cells in the ectocervix and to analyze the different morphologic varieties of argyrophil cell-containing ectocervical epithelia, notably to reappraise the degree of analogy with transitional epithelium. A systematic study of 39 ectocervices was carried out using histochemical and immunohistochemical techniques. Immunodetection of cytokeratins was used to specify the differentiation of the ectocervical linings. Argyrophilic cells were detected in 43% of our specimens. They have been found in several varieties of ectocervical lining: normal-appearing or hyperkeratotic squamous epithelium, "transitional-like" epithelium extending onto the portio, and immature squamous metaplasia from the transformation zone. The term "transitional-like" refers to a stratified nonsquamous epithelium that differs from true urothelium by the absence of superficial differentiation leading to the layer of "umbrella" cells. Two main types of argyrophilic cells have been delineated: serotonin cells and Merkel-type cells. The nature of the argyrophilic cells was dependent on the type of epithelium: Serotonin cells were essentially associated with "transitional-like" epithelium and Merkel-type cells with squamous epithelium. The latter cells were particularly frequent in hyperkeratotic squamous epithelium from uterine prolapse, reinforcing the homology with epidermis.

Adult↗
PubMed1997

Choroidal findings in the course of idiopathic serous pigment epithelium detachment detected by indocyanine green videoangiography.

PURPOSE: To analyze the choroidal alterations associated with idiopathic serous pigment epithelium detachment. METHODS: Twenty-five consecutive patients affected by idiopathic serous pigment epithelium detachment underwent ophthalmoscopy, fluorescein angiography, and indocyanine green videoangiography. RESULTS: On indocyanine green videoangiography an early, complete, and homogeneous filling of the pigment epithelium detachment was always observed. In the late phases, the indocyanine green pattern depended on the size of the detachment. An idiopathic serous pigment epithelium detachment larger than the diameter of one optic disk was still hyperfluorescent in the late phases of indocyanine green videoangiography and was surrounded by a ring of brighter hyperfluorescence. An idiopathic serous pigment epithelium detachment smaller than the diameter of one optic disk usually could be visualized in the late phases as a hypofluorescent area surrounded by a hyperfluorescent ring. In 30 eyes (83.3%), choroidal hyperpermeability was observed. An irregular dilatation of the choroidal veins at the site or within an area the size of one disk diameter from the detachments could be visualized on indocyanine green videoangiography in 12 of 36 affected eyes (33.3%); in three cases an active focus of central serous chorioretinopathy with subretinal leakage developed in the follow-up period. CONCLUSION: The observation that pigment epithelium detachments frequently are associated with choroidal leakage and venous dilatation supports the hypothesis that an idiopathic serous pigment epithelium detachment is a variant of central serous chorioretinopathy. Moreover, the choroidal permeability alterations detected by indocyanine green videoangiography would support the theory of Gass that idiopathic serous pigment epithelium detachments could be caused by exudation of fluids from the choroidal vessels.

Adult↗
PubMed1991

The response of female urogenital tract epithelia to mesenchymal inductors is restricted by the germ layer origin of the epithelium: prostatic inductions.

The epithelium of the mammalian vagina arises from two distinct germ layers, endoderm from the urogenital sinus and mesoderm from the Müllerian ducts. While neonatal vaginal epithelium can be induced to form prostate which is normally an endodermal derivative, it has not been determined whether this ability to form prostate is shared by both mesoderm- and endoderm-derived vaginal epithelia. To test the competence of vaginal epithelia we have isolated sinus-derived and Müllerian-derived vaginal epithelia from newborn mice, combined them with rat urogenital sinus mesenchyme, and grown the tissue recombinants for 4 weeks in male athymic nude mice. Endoderm-derived sinus vaginal epithelium was induced to form prostatic tissue which expressed prostate-specific secretory proteins in 21 of 23 tissue recombinants. Müllerian-derived vaginal epithelium formed small ducts and cysts lined by a simple epithelium. These latter tissue recombinants lacked any evidence of prostatic secretory proteins. Similarly, endoderm-derived urethral epithelium was induced to form prostate (17 of 17 cases), while mesoderm-derived uterine epithelium was not (0 of 13 cases). Therefore, the ability to form prostatic epithelium was limited to endodermal derivatives of the urogenital tract.

Androgen-Binding Protein↗
PubMed1986

The influence of epithelium on the responsiveness of guinea-pig isolated trachea.

This study was designed to investigate the possibility that tracheal epithelium generates a relaxant factor analogous to the endothelial-derived relaxant factor (EDRF) of vascular tissue. The absence of such a factor following epithelial damage in diseases such as asthma might help to explain the airway hyperreactivity characteristic of such diseases. Removal of epithelium by rubbing enhanced the sensitivity of guinea-pig isolated tracheal chains to 5-hydroxytryptamine, histamine, acetylcholine, adenosine, isoprenaline and also minimally to KCl. Responses to LaCl3 and electrical field stimulation were not affected. Low concentrations of adenosine produced contractions only in tissues denuded of epithelium. In the presence of indomethacin 1.4 microM or dithiothreitol (DTT) 1 microM, dose-response curves to histamine were moved to the left in both control and rubbed tissues, and the maximum response was increased. The difference in sensitivity between tissues with and without epithelium was not affected by indomethacin, but was slightly reduced by DTT. Phenidone (0.1 mM) also increased the maximum responses, but increased the sensitivity only of the tissues with intact epithelium, to the same level as that seen in the tissues denuded of epithelium. Superfusion cascade studies provided no evidence for the generation of a relaxant factor from tracheal epithelium. It is suggested that the supersensitivity produced by removal of the epithelium is not due to the removal of a relaxant factor, but rather to the removal of a permeability barrier, allowing a greater concentration of agonist at the level of the underlying smooth muscle.

Animals↗
PubMed1987

Relaxation of guinea-pig tracheal smooth muscle to arachidonate is converted to contraction following epithelium removal.

1 The effect of epithelium removal on responses of guinea-pig isolated trachealis to sodium arachidonate has been examined. 2 Arachidonate (100 microM) caused relaxation of epithelium-intact preparations, but following epithelium removal, the response to arachidonate was converted to contraction. In the presence of indomethacin (1 microM), arachidonate caused contraction in intact and denuded trachea. 3 Arachidonate also produced concentration-dependent effects, the qualitative nature of which varied with the presence or absence of the epithelium. In the presence of indomethacin, tracheal strips contracted in a concentration-dependent manner whether or not the epithelium had been removed. 4 Nordihydroguaiaretic acid (NDGA; 10 microM) markedly inhibited the contractile response of denuded strips to arachidonate. In intact tissues this lipoxygenase inhibitor converted the arachidonate-induced relaxation to a concentration-dependent contraction. The contraction to arachidonate, in the presence of NDGA, was epithelium-dependent. In the presence of both indomethacin and NDGA, responses to arachidonate were abolished. 5 It is concluded that the relaxation of guinea-pig trachea to arachidonic acid is epithelium-dependent and is mediated by an inhibitory product of the cyclo-oxygenase metabolic pathway. The contraction in denuded trachea, and trachea in the presence of indomethacin, may be mediated by lipoxygenase products of arachidonic acid metabolism, i.e. peptidoleukotrienes. The mediator of the epithelium-dependent contraction in NDGA-treated tissues is unknown.

Animals↗
PubMed1988

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

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.

Adenosine↗
PubMed1988

Comparison of the effects of epithelium removal and of an enkephalinase inhibitor on the neurokinin-induced contractions of guinea-pig isolated trachea.

1. The influence of epithelium removal and/or thiorphan on the effects of neurokinins (substance P (SP), neurokinin A (NKA), neurokinin B (NKB)) and related peptides on airway contractility was investigated on the guinea-pig isolated trachea. 2. Removing the tracheal epithelium significantly enhanced the sensitivity but not the maximum contractile responses to the peptides. 3. After removal of the epithelial layer, the shifts to the left of the log concentration response curves were greater for SP and SP-OMe (1.62 and 1.94 log units, respectively) than for two SP analogues substituted in position 9 namely [Pro9]SP sulfone and [beta-Ala4, Sar9]SP(4-11) sulfone (0.66 and 0.68 log units, respectively). The leftward shifts for compounds related to NKA or NKB lay between 0.58 and 0.73 log units. 4. The leftward shifts of the log concentration-response curves for SP, SP-OMe, [Pro9]SP sulfone, [beta-Ala4, Sar9]SP(4-11) sulfone and NKA were of similar magnitude after removal of the epithelium or after pretreatment with thiorphan (10(-5) M), an enkephalinase inhibitor, in the presence of epithelium. No significant additional shift of the curves to the left was observed with thiorphan plus epithelium removal. 5. The results obtained with the selective agonists for each of the three classes of neurokinin receptor (i.e NK1, NK2, NK3) suggest that the guinea-pig trachea contains receptors for SP and NKA but few if any for NKB. 6. It was concluded that neurokinins and related peptides (especially SP and analogues not substituted in position 9) are degraded by enkephalinase mainly located in the tracheal epithelium and that the addition of thiorphan or epithelium removal results in an inhibition or loss of enkephalinase activity, thereby increasing similarly the potencies of these peptides. It was, therefore, suggested that the supersensitivity to neurokinins produced by epithelium removal was due neither to the elimination of a permeability barrier nor to reduced production of a relaxant factor, but mainly to reduced peptide degradation.

Airway Resistance↗
PubMed1992

Characterization of muscarinic receptors that mediate contraction of guinea-pig isolated trachea to choline esters: effect of removing epithelium.

1. The muscarinic receptor subtype that mediates contraction of guinea-pig trachea, in the presence and absence of epithelium, to acetic and carbamic acid choline esters was determined by use of preferential muscarinic receptor antagonists: pirenzepine (M1 receptor), methoctramine (M2 receptor) and 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) (M3 receptor). 2. Acetylcholine (ACh), methacholine (MeCh), carbachol (CCh), bethanechol (BeCh) and oxotremorine induced concentration-dependent contraction of guinea-pig isolated tracheal strips in the presence and absence of epithelium. Contraction to acetic choline esters (ACh and MeCh) was augmented by removal of the epithelium, whereas contraction to carbamic acid choline esters (CCh and BeCh) and oxotremorine was not influenced by removal of the epithelium. 3. Pirenzepine, methoctramine and 4-DAMP caused parallel rightward displacements of the concentration-contraction curves to the muscarinic agonists. The pA2 values (determined from Arunlakshana-Schild graphs) for pirenzepine and 4-DAMP in guinea-pig trachea in the presence of epithelium were: ACh as the agonist, 7.6 and 9.0, respectively; CCh as the agonist, 7.6 and 9.1, respectively. The apparent pKB values for methoctramine with the same system were: ACh as the agonist, 5.6; CCh as the agonist, 5.6. Similar values were obtained with MeCh, BeCh and oxotremorine as the agonists. These values were agonist- and epithelium-independent. 4. It is concluded from the pA2 and apparent pKB values obtained for the muscarinic receptor antagonists used in this study that contraction of guinea-pig isolated trachea, with and without epithelium, to both acetic and carbamic acid choline esters is mediated via the muscarinic M3 receptor subtype.Differential contractile responses of guinea-pig trachea to acetic and carbamic acid choline esters upon the mechanical removal of the epithelium may not be explained by activation of different muscarinic receptor subtypes by these agonists.

Acetylcholine↗
PubMed2005

Immunohistochemical analysis of apoptosis-related factors in lining epithelium of radicular cysts.

BACKGROUND: Some studies suggest that apoptosis-related factors are involved in the inflammatory processes of marginal periodontal lesions. However, the role of apoptosis in periapical inflammatory lesions remains unclear. We investigated the possible role of apoptotic cell death in periapical inflammatory lesions by means of immunohistochemical analysis of apoptosis-related factors and use of a cell proliferation marker. METHODS: Paraffin-embedded sections of 19 radicular cysts (RCs), and five residual radicular cysts (RRCs) and control specimens of normal gingivae excised from seven cadavers were prepared and examined immunohistochemically with the use of monoclonal antibodies or polyclonal antisera against single-stranded DNA (ssDNA), p53, Bax, Bcl-2, caspase-3, Fas, Fas ligand (Fas-L), and Ki-67 antigen. RESULTS: Epithelium of gingiva, RCs, and RRCs showed expression of ssDNA in suprabasal and superficial epithelial cells and Ki-67 reactivity in basal and parabasal cells. Expression of Ki-67 and ssDNA in RCs and RRCs was slightly higher than that in gingiva. Both Ki-67 and ssDNA reactivity in RCs with intense inflammatory reactions or with thick lining epithelium were significantly stronger than those in RCs with less inflammatory reactions or with thin lining epithelium. Reactivity for p53 was noted sporadically in epithelium of gingiva, RCs, and RRCs, and p53 expression in RCs was significantly greater than that in gingiva. Ki-67 and ssDNA reactivity in RCs increased parallel to the degree of p53 expression. Bax and Bcl-2 were detected in some basal epithelial cells in RCs and RRCs as well as in gingiva. The ssDNA reactivity significantly increased parallel to Bax expression and slightly decreased parallel to Bcl-2 expression in lining epithelium of RCs. Caspase-3 was detected in superficial epithelial cells of both gingiva and lining epithelium of RCs and RRCs, and the distribution of these cells was compatible with the expression of ssDNA. Expression of Ki-67 and ssDNA in caspase-3-positive fields was significantly higher than that in caspase-3-negative fields in RCs. There was very limited expression of Fas and Fas-L in lining epithelium of RCs and RRCs as well as in gingiva. CONCLUSIONS: These data suggest that apoptosis-related factors are involved in the pathophysiologic activity of periapical inflammatory lesions. Such factors may be affected by the structure of lining epithelium and the degree of inflammatory change.

Adult↗
PubMed1991

Association between keratin staining patterns and the structural and functional aspects of palatine tonsil epithelium.

The keratin composition of stratified squamous epithelia has a complex pattern, which varies in different regions and as a result of pathological developments. The exact factors responsible for the characteristic keratin composition in a given epithelium are unknown. However, the environment, including factors from the connective tissue, is known to influence epithelial morphology and keratin composition. We here report that the reticulated squamous epithelium of the crypts of palatine tonsils shows an extensive staining for keratins 5 and 19 in basal as well as suprabasal cells, in contrast to neighbouring non-reticulated crypt epithelium and the epithelium at the tonsillar surface, in which staining is restricted to basal cells. The reticulation of the crypt epithelium is thought to be initiated by infiltration of immune-related cells in a preexistent non-reticulated epithelium. The extensive staining for keratins 5 and 19 in reticulated crypt epithelium correlates with the presence of numerous immune system-related cells and marked expression of intercellular adhesion molecule-1 (ICAM-1), thought to be involved in inflammatory and immunological responses. The results suggest that the massive lymphocytic traffic in the reticulated crypt epithelium and the overall distinct immune environment are responsible for the unique keratin staining pattern observed.

Adolescent↗
PubMed1997

Biochemical analysis of the stress protein response in human oesophageal epithelium.

BACKGROUND: The oesophageal epithelium is exposed routinely to noxious agents in the environment, including gastric acid, thermal stress, and chemical toxins. These epithelial cells have presumably evolved effective protective mechanisms to withstand tissue damage and repair injured cells. Heat shock protein or stress protein responses play a central role in protecting distinct cell types from different types of injury. AIM: To determine (i) whether biochemical analysis of stress protein responses in pinch biopsy specimens from human oesophageal epithelium is feasible; (ii) whether undue stresses are imposed on cells by the act of sample collection, thus precluding analysis of stress responses; and (iii) if amenable to experimentation, the type of heat shock protein (Hsp) response that operates in the human oesophageal epithelium. METHODS: Tissue from the human oesophagus comprised predominantly of squamous epithelium was acquired within two hours of biopsy and subjected to an in vitro heat shock. Soluble tissue cell lysates derived from untreated or heat shocked samples were examined using denaturing polyacrylamide gel electrophoresis for changes in: (i) the pattern of general protein synthesis by labelling epithelial cells with 35S-methionine and (ii) the levels of soluble Hsp70 protein and related isoforms using immunochemical protein blots. RESULTS: A single pinch biopsy specimen is sufficient to extract and analyse specific sets of polypeptides in the oesophageal epithelium. After ex vivo heat shock, a classic inhibition of general protein synthesis is observed and correlates with the increased synthesis of two major proteins of molecular weight of 60 and 70 kDa. Notably, cells from unheated controls exhibit a "stressed" biochemical state 22 hours after incubation at 37 degrees C, as shown by inhibition of general protein synthesis and increased synthesis of the 70 kDa protein. These data indicate that only freshly acquired specimens are suitable for studying stress responses ex vivo. No evidence was found that the two heat induced polypeptides are previously identified Hsp70 isoforms. In fact, heat shock results in a reduction in the steady state concentrations of Hsp70 protein in the oesophageal epithelium. CONCLUSION: Systematic and highly controlled studies on protein biochemistry are possible on epithelial biopsy specimens from the human oesophagus. These technical innovations have permitted the discovery of a novel heat shock response operating in the oesophageal epithelium. Notably, two polypeptides were synthesised after heat shock that seem to differ from Hsp70 protein. In addition, the striking reduction in steady state concentrations of Hsp70 protein after heat shock suggests that oesophageal epithelium has evolved an atypical biochemical response to thermal stress.

Biopsy↗
PubMed1988

Airway epithelium modulates the responsiveness of porcine bronchial smooth muscle.

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.

Acetylcholine↗
PubMed1991

Role of the epithelium in airway smooth muscle responses to relaxant agonists.

We studied the role of the guinea pig tracheal epithelium in modulating tracheal smooth muscle responses to the relaxant agonists albuterol, sodium nitroprusside, and theophylline. We used an in vitro preparation that allowed separation of the fluids bathing the luminal (internal) and serosal (external) surfaces of the trachea, and bronchodilators were administered to either surface of carbachol-contracted tracheae. All three drugs produced dose-dependent relaxation. However, albuterol and nitroprusside were less potent (concentration that produced half-maximal effect increased by 100- and 32-fold, respectively) when given to the epithelial side with the epithelium intact compared with the epithelium denuded or compared with serosal administration with the epithelium intact. These differences were not observed for theophylline, where smooth muscle responses were independent of either the side of stimulation or of the presence or absence of the epithelium. Direct measurements of the diffusion of theophylline across the tracheal wall in the presence or absence of epithelium showed that after 5 h of incubation with a fixed luminal concentration of theophylline, only 1.7% had diffused across the tracheal wall with the epithelium intact. This increased to only approximately 3.3% when the epithelium was denuded. These results suggest that the epithelial is a relatively weak barrier for lipophilic agents but has a major role as a diffusion barrier to hydrophilic substances.

Albuterol↗
PubMed1993

In vivo antioxidant gene expression in human airway epithelium of normal individuals exposed to 100% O2.

Human bronchial epithelium is exquisitely sensitive to high O2 levels, with tracheobronchitis usually developing after 12 h of exposure to 100% O2. To evaluate whether this vulnerability results from inability of the bronchial epithelium to provide adequate antioxidant protection, we quantified antioxidant gene expression in bronchial epithelium of normal volunteers at baseline and after exposure to 100% O2 in vivo. After 14.8 +/- 0.2 h of 100% O2, 24 of 33 individuals had evidence of tracheobronchitis. Baseline gene expression of CuZn superoxide dismutase (SOD), MnSOD, and catalase in bronchial epithelium was very low (CuZnSOD 4.1 +/- 0.8 transcripts/cell, MnSOD 5.1 +/- 0.9, catalase 1.3 +/- 0.2), with control gamma-actin expression relatively abundant (50 +/- 6 transcripts/cell). Importantly, despite 100% O2 exposure sufficient to cause tracheobronchitis in most individuals, antioxidant mRNA transcripts/cell in bronchial epithelium did not increase (P > 0.5). Catalase activity in bronchial epithelium did not change after exposure to hyperoxia (P > 0.05). Total SOD activity increased mildly (P < 0.01) but not sufficiently to protect the epithelium. Together, the very low levels of expression of intracellular antioxidant enzymes and the inability to upregulate expression at the mRNA level with oxidant stress likely have a role in human airway epithelium susceptibility to hyperoxia.

Actins↗
PubMed1994

Epithelium acts as a modulator and a diffusion barrier in the responses of canine airway smooth muscle.

The present study was designed to determine the role of the respiratory epithelium as a diffusion barrier and a modulator of the responsiveness of airway smooth muscle to bronchoactive agents. Segments of canine bronchi, with or without epithelium, were suspended in organ chambers and perfused intraluminally. The isometric tension was recorded. Acetylcholine, given intraluminally, induced significantly smaller contractions in bronchi with than in bronchi without epithelium. When this agonist was given extraluminally, no difference in contractions was noted between the tissues. In the presence of acetylcholine and phentolamine, norepinephrine, given either intra- or extraluminally, induced significantly larger relaxations in bronchi with than in bronchi without epithelium. High potassium given intraluminally induced contractions only in bronchi without epithelium; however, in the presence of ouabain, both tissues contracted similarly. When high potassium was given extraluminally, no difference in contraction between tissues with and without epithelium was noted. When [3H]acetylcholine and [3H]norepinephrine were perfused intraluminally, the accumulation of 3H radioactivity in the extraluminal solutions was significantly less in bronchi with than in bronchi without epithelium. These observations suggest that the epithelium acts as both a diffusion barrier and a modulator of the responses of canine airways to bronchoactive agents.

Acetylcholine↗