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PubMed1992

Role of acetylcholinesterase in airway epithelium-mediated inhibition of acetylcholine-induced contraction of guinea-pig isolated trachea.

To seek evidence for the involvement of acetylcholinesterase activity in the modulatory influence of the airway epithelium, we examined responses to acetylcholine (ACh), bethanechol, histamine or KCl in isolated epithelium-intact and epithelium-denuded guinea-pig trachealis preparations. The concentration-response curves to ACh were shifted 26-fold to the left by epithelial denudation but the contractile response to KCl was not altered. The response to histamine in epithelium-denuded preparations increased 4-fold with no attenuation in the presence of physostigmine (30 nM). Physostigmine (30 nM) potentiated the response to ACh in epithelium-intact tissues more (about 26-fold) than in epithelium-denuded tissues (about 3.5-fold). Thus, in the presence of physostigmine removing the epithelium had only a slight effect (not statistically significant) on the potency of ACh to contract the trachea. Removing the epithelium had no effect on the potency of bethanechol, a muscarinic receptor agonist that is not a substrate for cholinesterases. Physostigmine itself contracted the trachealis muscle but the pD2 values and maximum responses in epithelium-intact and denuded preparations were not significantly different. The frequency-response curves to electrical field-stimulated cholinergic contractions were unaffected by removing the epithelium. In conclusion, the principal mechanism by which the epithelium inhibits contraction of guinea-pig trachea to exogenously applied ACh is via epithelium-derived acetylcholinesterase activity.

Acetylcholine↗
PubMed2005

Changes in the distribution of laminin-5 during peri-implant epithelium formation after immediate titanium implantation in rats.

Laminin-5 (Ln-5), a component of the basement membrane (BM), regulates epithelial cell migration and adhesion. This study used anti-Ln-5 (gamma2chain) antibody to investigate the distribution of Ln-5 during the formation of peri-implant epithelium (PIE) in rats, and compared it to the distribution of Ln-5 during oral mucosa formation after tooth extraction. One day after extraction, the junctional epithelium (JE) had disappeared. After 3 days, new epithelium formed from the oral sulcular epithelium (OSE) and extended horizontally over the wound with Ln-5-positive cells at the leading edge. After 5 days, the epithelium extending from the OSE on each side of the wound joined and formed additional new epithelium. The new epithelium expressed Ln-5 in the BM. After 1-2 weeks, the oral epithelium (OE) extending from the sides of the wound joined in the center. Thereafter, OSE and new epithelium disappeared, and only OE remained covering the wound. Three days after implantation (titanium), no JE remained. New epithelium formed from the keratinized OSE extending apically with Ln-5-positive cells. After 1-2 weeks, the new epithelium became the PIE and spread further apically facing the implant surface. Ln-5 was expressed at the PIE-connective tissue interface, but not at the implant-PIE interface. Finally, after 4 weeks, Ln-5 was expressed at the implant-PIE interface, and the PIE was non-keratinized epithelium. These findings suggest that Ln-5 induces cell migration during PIE formation, and that PIE originates from OSE. Furthermore, they support the hypothesis that Ln-5 contributes to the attachment of PIE to titanium, regardless of the delay in the synthesis and deposition of Ln-5 at the titanium-PIE interface.

Animals↗
PubMed1992

The germ layer origin of mouse vaginal epithelium restricts its responsiveness to mesenchymal inductors: uterine induction.

The epithelium of the mammalian vagina arises from two distinct germ layers, endoderm from the urogenital sinus and mesoderm from the lower fused Müllerian ducts. While previously it has been reported that neonatal vaginal epithelium can be induced to differentiate as uterus, which normally develops from the middle portion of the Müllerian ducts, it has not been determined whether this ability is shared by both mesoderm- and endoderm-derived vaginal epithelia. To test if germ layer origin influences the ability of vaginal epithelium to undergo uterine differentiation, we have isolated sinus-derived and Müllerian-derived vaginal epithelia from newborn mice, combined them with uterine mesenchyme, and grown them for 4 weeks in female mice. Mesoderm-derived Müllerian vaginal epithelium in combination with uterine mesenchyme formed the simple columnar epithelium typical of uterus. Similar results were obtained with neonatal cervical epithelium, another mesodermal Müllerian duct derivative. On the other hand, sinus vaginal epithelium combined with uterine mesenchyme formed small cysts lined by a stratified squamous vaginal-like epithelium. This epithelium never showed evidence of cycling between the cornified and mucified states as is typically seen in vaginal epithelium combined with vaginal stroma. These results indicate that the ability of epithelium to form uterus is limited to mesoderm-derived epithelia and suggest that endoderm-derived sinus vaginal epithelium cannot undergo the typical differentiative modifications in response to the hormonal fluctuations of the estrous cycle when associated with uterine stroma.

Animals↗
PubMed1994

Epithelium modulates the kinetics of the response to substance P and its intrinsic activity in the guinea-pig trachea.

The contractile response of guinea-pig tracheal preparations with or without epithelium to substance P has been studied in the presence or absence of thiorphan, an endopeptidase 24.11 inhibitor, paying special attention to the kinetics of the response. Without thiorphan, the response to substance P was greater in tracheal preparations without epithelium than in tracheal preparations with epithelium. The concentration-response curve was shifted to the left in the absence of the epithelium. In the presence of 10 microM thiorphan, the maximal contractile response induced by single doses of substance P (0.1 to 10 microM) was lower in tracheal preparations without epithelium. The maximal responses required 10 min in tracheal preparations with epithelium and 2 min in tracheal preparations without epithelium. These epithelium-dependent differences of reactivity remained in the presence of lipoxygenase or cyclooxygenase inhibitors and of selective antagonists of muscarinic, serotoninergic and histaminergic receptors, after the pre-treatment of tissues with capsaicin or compound 48/80 and in the presence of tetrodotoxin. The profile of the cumulative concentration-response curves for substance P was largely dependent on the time between two successive doses. When this time was short (2-4 min), curves established with or without the epithelium were parallel and both reached similar maximal values (2696 +/- 214 mg and 2780 +/- 62 mg, respectively). The curve in tracheal preparations without epithelium was slightly shifted to the left (EC50s: 24 +/- 10 nM and 78 +/- 19 nM). When this time was longer (10 min, ie corresponding to the time required for a full response to a single dose in intact trachea) the potency of substance P was not modified (EC50s: 13 +/- 3 nM and 52 +/- 11 nM), but a lower maximal response was observed with tracheal preparations without epithelium (1440 +/- 182 mg and 2832 +/- 209 mg). Similar results were observed with neurokinin A and neurokinin B. Thus, the removal of the epithelium led to a more rapid contraction and to a decrease of the maximal response to neurokinins, ie a decreased intrinsic activity, a property known to be drug- and tissue-dependent. These data suggest that the intrinsic activity of drugs depends on the cellular environment of the target cells in a tissue and is partly related to the diffusion and metabolism of drugs and to drug-induced hyporeactivity of the target cells.

Animals↗
PubMed1988

A possible role of airway epithelium in modulating hyperresponsiveness.

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.

Acetylcholine↗
PubMed1993

Respiratory epithelium modulates the responses of canine bronchi to cooling.

The present study was designed to investigate the effect of cooling on the modulatory role of the respiratory epithelium on the underlying smooth muscle. Canine bronchial rings and segments (with or without epithelium) were suspended in organ chambers and perfused with modified Krebs-Ringer bicarbonate solution, respectively. Isometric force was recorded. Cooling did not affect the resting tension of the bronchi. During contractions to carbachol, cooling evoked contractions in bronchi with epithelium but relaxations in those without epithelium. In the presence of indomethacin, cooling induced contractions in both preparations with and without epithelium. The contractions in bronchi with epithelium were significantly larger than those in bronchi without epithelium. After treatment with indomethacin, exogenous arachidonic acid potentiated the cooling-induced contractions in preparations with epithelium but not in those without epithelium. This potentiation was not affected by nordihydroguaiaretic acid. SKF 525-A and metyrapone, inhibitors of cytochrome P-450 monooxygenases, converted the cooling-induced contractions of preparations with epithelium to relaxations and had no significant effects on the responses of preparations without epithelium. These observations suggest that cooling induces from the epithelium the release of a cytochrome P-450-derived eicosanoid that potentiates contractions of the underlying airway smooth muscle to carbachol.

Animals↗
PubMed1984

The human thymic microenvironment: cortical thymic epithelium is an antigenically distinct region of the thymic microenvironment.

The thymic microenvironment is a complex tissue essential for normal T cell maturation. Prothymocytes in the subcapsular cortical (SCC) region of the thymus undergo cell division and migrate to the inner cortex. The majority of cortical thymocytes cease dividing and die, but a minority are exported to the periphery. We have previously shown thymic hormones in SCC and medullary thymic epithelium and have identified a monoclonal antibody (TE-4) that defines human endocrine thymic epithelium. However, no marker that selectively defines cortical thymic epithelium has been available. In this study, we have produced two monoclonal antibodies, TE-3A and TE-3B, raised against human thymic stroma that bind to an intracellular antigen in cortical but not medullary thymic epithelium. In double immunofluorescence assays in which we used anti-keratin, anti-thymosin alpha 1, and anti-endocrine thymic epithelium antibodies (TE-4, A2B5), TE-3+ SCC epithelium was TE-4+ and contained keratin and thymosin. alpha 1. In contrast, TE-3+ inner cortical epithelium was TE-4/A2B5 nonreactive and did not contain thymosin alpha 1. An ontogeny study of seven fetal and five neonatal thymuses demonstrated that expression of the TE-3 antigen was acquired at 10 wk fetal gestation. Using TE-3 antibody, we observed sequential stages of separation of cortical and medullary epithelium from 12 to 20 wk fetal gestation. In dysplastic (severe combined immunodeficiency disease) thymuses, strands of TE-3+ nonendocrine cells encircled nests of TE-4+ endocrine epithelium. Thus, human cortical thymic epithelium is antigenically distinct from endocrine medullary epithelium. Antibodies against the TE-3 antigen define an intracellular molecule that may reflect a specialized function of cortical thymic epithelium.

Adolescent↗
PubMed1996

Release and actions of inhibitory prostaglandins from canine tracheal epithelium.

This study evaluated the sources and actions of inhibitory prostanoids on canine tracheal smooth muscle to determine if these accounted for epithelium derived relaxing factor activity. Concentration-response curves of canine tracheal smooth muscle were generated to carbachol in the presence and absence of the epithelium and (or) indomethacin, a cyclooxygenase inhibitor. Removal of the epithelium or addition of indomethacin (10(-5) M) in the presence of the epithelium shifted the curve significantly leftward compared with epithelial-intact tissue. Furthermore, addition of indomethacin to epithelial-denuded tissue produced the greatest shift in the curve. Removal of the epithelium increased contractility in response to electrical-field stimulation at intermediate frequencies compared with epithelium-intact tissues. The addition of indomethacin to epithelium-intact tissue also increased the contractile responses. Removal of the epithelium in the presence of indomethacin further increased responses. Radioimmunoassay of muscle bath fluid indicated that the inhibitory prostanoids prostaglandin I2 (PGI2) and prostaglandin E2 (PGE2) were released. PGI2 was released from the epithelium as well as from a nonepithelial source. PGE2 was released from the epithelium in response to electrical-field stimulation. The release of PGE2 was greatly reduced by the addition of indomethacin (10(-5) M), but not by the addition of omega-conotoxin (GVIA), an N-type Ca2+ channel antagonist, nor by the addition of tetrodotoxin, a Na+ channel blocker. Both toxins abolished contractions to electrical-field stimulation. We conclude that the inhibitory prostanoids PGI2 and PGE2 are released, along with a nonprostanoid factor from epithelium, and modulate airway smooth muscle contractility to stimulation of cholinergic nerves and muscarinic agonists. PGE2 is released from epithelium by electrical-field stimulation independent of nerve function.

Animals↗
PubMed2004

[The effect of acetylcholine, dopamine, histamine and serotonin in the tracheal smooth muscle in the response with desquamative and non-desquamative epithelium of respiratory pathways in vitro].

In this paper we have examined the receptor bronchial system in newly born children with desquamative and with preserved epithelium of aerial pathways. The response was followed in: acetylcholine, dopamine, histamine and scrotonin in various concentrations (10(-4), 10(-3), 10(-2), 10(-1)). The tonus of the tracheal smooth muscle was examined in 29 tracheal preparations, taken by autopsy after excitation from various factors. On the basis of functional investigation it has been established as follows: acetylcholine had caused the response of the bronchial smooth muscle with desquamative epithelium in a significant way (p < 0.01), in contrast to cases which were treated with unimpaired epithelium (p > 0.1). The effect of dopamine was significant in cases with desquamative epithelium (p < 0.05), in contrast to cases where epithelium was preserved (p > 0.1). The effect of histamine was also significant in cases with desquamative epithelium of respiratory pathways (p < 0.01), in contrast to cases where epithelium was preserved. Cases with desquamative epithelium in serotonin have reacted significantly (p < 0.01), despite cases which had no impaired epithelium of respiratory pathways (p > 0.1). Obtained results show that the response of the tracheal discs with desquamative epithelium of respiratory pathways was significant (p < 0.01), despite cases which had preserved the epithelium of respiratory pathways (p > 0.1). This suggest that various mediators with local effect are released during desquamation of epithelium which increase thus the bronchial reactibility of respiratory pathways.

Acetylcholine↗
PubMed1998

Spatial pattern of smooth muscle differentiation is specified by the epithelium in the stomach of mouse embryo.

Smooth muscle induction in the stomach of mouse embryo was analyzed experimentally by tissue recombination and organ culture technique. When observed immunohistochemically with anti-alpha-smooth muscle actin antibody, smooth muscle myoblasts first differentiated and formed the circular muscle layer at 13 days of gestation. The longitudinal muscle layer appeared at 15 days in the forestomach and at neonatal period in the glandular stomach. The lamina muscularis mucosae was observed by the neonatal period. When the undifferentiated 11-day stomach was cultivated in vitro for 3 days, an alpha-smooth muscle actin-positive cell layer was formed and the explant exhibited rhythmical contraction. The mesenchyme alone remained as an undifferentiated cell mass. When the mesenchyme was recombined with the epithelium, a distinct smooth muscle layer was formed. These demonstrated that the alpha-smooth muscle actin expression was induced by the epithelium. Next, we examined by heterologous recombination the roles of the epithelium in formation of the organ-specific spatial pattern of smooth muscle differentiation. The stomach mesenchyme recombined with the tracheal epithelium exhibited a partially tracheal type of alpha-smooth muscle actin expression. The uterine epithelium induced only a small number of smooth muscle myoblasts and the spatial organization was disordered. Finally, we assayed if the mode of smooth muscle induction by the stomach epithelium changes during development. Heterochronic recombination proved that the 14-day forestomach epithelium induced a muscularis mucosae-like smooth muscle layer that was contiguous to the epithelium, whereas the 11-day stomach and the 13-day forestomach epithelium induced a circular muscle-like smooth muscle layer that was distant from the epithelium. As a whole, our data suggest that the spatial pattern of smooth muscle differentiation is regulated by organ-specific and stage-specific influences from the epithelium.

Actins↗
PubMed1990

Organization of projections from olfactory epithelium to olfactory bulb in the frog, Rana pipiens.

One hypothesis for the coding of olfactory quality is that regions of the olfactory epithelium are differentially sensitive to particular odor qualities and that this regional sensitivity is conveyed to the olfactory bulb in a topographic manner by the olfactory nerve. A corollary to this hypothesis is that there is a sufficiently orderly connection between the epithelium and the olfactory bulb to convey this topographical coding. Thus we examined topography in the projection from epithelium to bulb in the frog, which has been the subject of numerous electrophysiological studies but has not yet been examined using modern neuroanatomical techniques. The tracer WGA-HRP was applied to the ventral or to the dorsal olfactory epithelium, or both. Anterograde transport of label to the olfactory bulb was seen after as few as 2 days; label was still present in the bulb as long as 21 days postinjection. In cases where WGA-HRP was applied to the entire epithelium, there was dense anterograde labelling of the ipsilateral olfactory bulb. In addition, a small medial portion of the contralateral bulb was labelled. Injections limited to either the ventral or dorsal epithelium produced patterns of anterograde labelling in the glomerular layer of the olfactory bulb, which varied with the size and location of the injection. With very large injections in either the dorsal or ventral epithelium, label appeared to be evenly distributed in the glomerular layer. With smaller injections in the ventral epithelium, there was heavier labelling in the lateral than in the medial portions of the glomerular layer, although light labelling was found in all regions of the glomerular layer. In contrast, injection sites restricted to the dorsal epithelium produced more anterograde labelling in the medial than lateral portions of the glomerular layer. These patterns extended throughout the dorsal-ventral extent of the bulb. Within the limits of the anterograde tracing technique used, we were unable to detect any systematic relationship between the pattern of labelling in the glomerular layer and the medial-lateral or rostral-caudal location of the injection site in either the ventral or dorsal epithelium. We conclude that in the frog, as in other amphibia, there is only a limited degree of topographic order between the epithelium and the olfactory bulb.

Animals↗
PubMed1990

Expression of the WE3 antigen in newt epithelium originating from subcutaneous grafts of skin.

mAb WE3 recognizes an antigen that is developmentally regulated in the wound epithelium of regenerating newt limbs. The antigen is precociously expressed when pieces of WE3-negative wound epithelium are grafted subcutaneously (Tassava et al.: Recent Trends in Regeneration Research. New York: Plenum Publishing Co., pp. 37-49, 1989). In the present study, we investigated whether the WE3 antigen is expressed in epidermis of subcutaneous grafts of skin. Small pieces of limb skin were grafted into small tunnels in the lower jaw, limb, and tail, oriented either the same as (epidermis facing out) or opposite to (epidermis facing in) the orientation of the host skin. In most cases, the epithelium migrated from the graft along the wounded surface of the tunnel, closed onto itself, and formed a multilayered "emigrant" epithelium. Infrequently, the migrating epithelium combined with the wound epithelium of the insertion wound. In no case did the epithelium migrate over the cut edge of the grafted dermis. Reactivity to mAb WE3 was first seen at 4 days after grafting, when the migrating epithelium had almost closed over onto itself. By 6 days and thereafter, the entire emigrant epithelium was reactive to mAb WE3. While initially restricted to the emigrant epithelium, at 10 days after grafting and thereafter, reactivity was also seen in the epidermis that remained in contact with the dermis. Expression of the WE3 antigen was not influenced by the orientation of the graft nor by the graft site. The results show that, compared to amputated limbs, the epithelium originating from these grafts precociously expresses the WE3 antigen. Also, epidermis of grafted skin is capable of expressing the WE3 antigen.

Animals↗
PubMed1989

Immune cells associated with M cells in the follicle-associated epithelium of Peyer's patches in the rat. An electron- and immuno-electron-microscopic study.

Follicle-associated epithelium of Peyer's patches can be differentiated from nearby villous epithelium by the presence of M cells which are antigen-sampling epithelial cells, and by an increase in intraepithelial lymphocytes that are in close contact with M cells. The phenotype of the immune cells close to the M cells of the follicle-associated epithelium of rat Peyer's patches was determined by immunohistochemistry and compared with that of the intra-epithelial lymphocytes of the villous epithelium. Lymphoid T cells, predominantly of the cytotoxic/suppressor phenotype, were observed both in follicle-associated epithelium and in villous epithelium. Lymphoid B cells, mainly immunoblasts and plasma cells containing intracytoplasmic IgM, were present only in the follicle-associated epithelium, near M cells. Macrophages were also present, in contact with M cells, in follicle-associated epithelium, but not in villous epithelium. In addition, M cells bore Ia molecules on their apical membranes. These findings reinforce the concept of immune specialization of the follicle-associated epithelium, by demonstrating that this epithelium contains all the effector cells of immune responses.

Animals↗
PubMed2004

Short-term study of retinal pigment epithelium sheet transplants onto Bruch's membrane.

The purpose of this study is to investigate the survival and behaviour of retinal pigment epithelium sheets transplanted onto hydraulically debrided Bruch's membrane. Uncultured retinal pigment epithelium sheets obtained from male cats and sandwiched between two gelatin sheets were transplanted onto the tapetal area of female cats after native retinal pigment epithelium was debrided. For controls, the gelatin carrier was transplanted after debridement. Each transplant or control specimen was analyzed histologically and immunohistochemically. Transplanted male retinal pigment epithelial cells were identified by in situ labelling of the cat Y chromosome. Over half of the transplants appeared as retinal pigment epithelium multilayers in the subretinal space. Retinal pigment epithelium pigment dispersion into the subretinal space was seen in most of the transplants, and retinal pigment epithelium pigment infiltration into the neural retina was seen in all 7-day survival transplants. A few condensed darkly stained retinal pigment epithelium nuclei and Terminal Transferase dUTP Nick End Labelling-positive retinal pigment epithelium cells were observed in all transplants. Cellular retinaldehyde-binding protein was present up to day-7 in most transplanted RPE cells. In both transplant and control specimens, the antibody against the Ki-67 nuclear antigen labelled a few retinal pigment epithelium cells at day-3. Terminal Transferase dUTP Nick End Labelling-positive outer nuclear layer nuclei were most frequently observed at day-1 but were much less frequent at day-3 in both transplants and controls. The survival and effectiveness of retinal pigment epithelium sheet transplants appeared similar to the retinal pigment epithelium microaggregates transplants conducted previously in this model.

Animals↗
PubMed1990

Modulation of the reactivity of the guinea-pig isolated trachealis by respiratory epithelium: effects of cooling.

1. Examination has been made of the effects of epithelium removal on the reactivity of guinea-pig trachealis to methacholine at 37 degrees C and 22 degrees C, and on responses to activation of the Na+/K(+)-pump by abrupt temperature increase from 22 degrees C to 37 degrees C. 2. At 37 degrees C, epithelium removal increased the sensitivity of isolated tracheal strips to methacholine without affecting the maximum isometric contractile response. Epithelium removal resulted at 22 degrees C in a decrease in sensitivity to methacholine, i.e. an effect opposite to that seen at 37 degrees C. While the maximum response of intact strips to methacholine was enhanced at 22 degrees C, the maximum response of denuded preparations was decreased. 3. The increase in sensitivity to methacholine at 37 degrees C after epithelium removal was mimicked in intact preparations by indomethacin (1 microM). Indomethacin did not mimic the decrease in methacholine sensitivity and maximum response caused by epithelium removal at 22 degrees C. 4. Following incubation at 22 degrees C, abrupt increase in temperature to 37 degrees C elicited relaxation in both epithelium-containing and epithelium-denuded tracheal strips. In epithelium-containing preparations the relaxation was more pronounced and followed by contraction. Ouabain (1 microM) converted the relaxation of denuded preparations to contraction, but was ineffective in intact strips. The relaxation of intact strips was, however, inhibited by a greater ouabain concentration (10 microM). 5. These findings indicate that the modulatory effect of the epithelium is temperature-dependent. In cooled preparations, the epithelium enhances reactivity. At 37 degrees C, an epithelium-derived factor reduces reactivity, and this may partially be due to activation of the electrogenic Na+/K+-pump.

Animals↗
PubMed1990

The effects of epithelium removal on the actions of cholinomimetic drugs in opened segments and perfused tubular preparations of guinea-pig trachea.

1. Isolated segments of guinea-pig trachea or perfused tracheal tubes were arranged for the recording of trachealis tension changes in Krebs solution containing indomethacin (2.8 microM). 2. In opened tracheal segments, epithelium removal caused modest (2-3 fold) potentiation of the effects of acetylcholine (ACh) and methacholine (MeCh) but failed to potentiate carbachol (CCh), bethanechol (BeCh), oxotremorine or KCl. 3. Pretreatment with ecothiopate potentiated effects of ACh and MeCh but not of CCh or BeCh. Removal of epithelium in ecothiopate-treated tissue potentiated effects of ACh and MeCh but not of CCh or BeCh. 4. Guinea-pig ileum challenged with ACh was used as a bioassay system for cholinesterase activity. Scrapings of tracheal epithelium did not hydrolyse ACh. 5. Histochemical staining revealed no fibres positive for acetylcholinesterase or pseudocholinesterase in the tracheal epithelium. However, the underlying tissues contained acetylcholinesterase-positive nerve fibres and the trachealis muscle itself stained positively for pseudocholinesterase activity. 6. Neither tetrodotoxin (3 microM) nor hexamethonium (500 microM) modified the ability of epithelium removal to potentiate ACh. 7. In perfused tracheal tubes where spasmogens were added to the luminal perfusate, epithelium removal potentiated effects of ACh (31 fold), CCh (10 fold), oxotremorine (2 fold) and KCl. 8. In perfused tracheal tubes where spasmogens were added to the Krebs solution superfusing the adventitial surface of the tissue, epithelium removal significantly reduced the potency of CCh, oxotremorine and KCl. 9. It is concluded that the selectivity and magnitude of the potentiation of cholinomimetics caused by epithelium removal depends on the route by which the cholinomimetic agent gains access to the trachealis muscle. The potentiation of acetic acid esters of choline seen in opened tracheal segments does not reflect the loss of epithelial cholinesterase activity and does not depend on the activity of nervous reflex arcs in the tracheal wall. The reduced potency of adventitially-applied cholinomimetics and KCl seen in epithelium-denuded tissue strongly suggests that the epithelium can moderate trachealis sensitivity to cholinomimetic agents not only by releasing epithelium-derived relaxing factor but also by acting as a barrier to drug diffusion.

Animals↗
PubMed1986

Immunohistochemical study of structural proteins in developing junctional epithelium.

The objective of this study was to investigate structural proteins of ameloblasts, reduced enamel epithelium and junctional epithelium using antikeratin antibodies to determine if keratin expression changes as ameloblasts differentiate to cells of junctional epithelium. Block sections of fully erupted, partially erupted and unerupted molar and incisor teeth were removed at necropsy from monkeys age 2, 5, 6 and 7 years. Tissues were fixed in Carnoy's fixative, decalcified in Kristensen's solution for 4 to 8 weeks, embedded in paraffin and sectioned at 5 mu. Representative sections were stained with hematoxylin and eosin. Remaining sections were stained with antikeratin antibodies AE1, AE3, 34 beta E12, 35 beta H11 and anti-40kD using the avidin-biotin-conjugated immunoperoxidase method. Results were analyzed qualitatively for presence or absence of staining products. Antibody 35 beta H11 reacted with ameloblasts and reduced enamel epithelium during the early maturation phase of tooth development but not with the reduced enamel epithelium of erupting teeth or with junctional epithelium. The anti-40kD antibody stained ameloblasts and reduced enamel epithelium of unerupted teeth and teeth erupting through oral epithelium; however, junctional epithelium of partially erupted and fully erupted teeth were unstained. Antibodies AE1, AE3 and 34 beta E12 stained ameloblasts and all layers of reduced enamel epithelium and junctional epithelium in all stages of development. These results suggest a relationship between expression of structural proteins and changes during development and differentiation of ameloblasts to junctional epithelial cells.

Ameloblasts↗
PubMed2002

[Changes of glycogen or sacchariferous materials in esophageal epithelium tissue].

BACKGROUND & OBJECTIVE: It was known that mucosal iodine staining could be used to improve the endoscopic visualization of esophageal premalignant lesion and cancer. However, the method was not used widely because of lacking clear mechanism. This study was designed to investigate the mechanism of esophageal epithelium staining with iodine and changes of glycogen or sacchariferous materials. METHODS: Esophageal epithelium was stained with iodine in endoscopic examination. According to color of tissue, the esophageal carcinoma and premalignant lesion were diagnosed. Glycogen from the esophageal mucous epithelium was extracted with beta-glycerophosphate buffer. The content of glycogen in the tissue speciman was detected by periodic acid-shiff staining (PAS). Protein in the esophageal mucous epithelium was extracted by tissue homogenate method. RESULTS: After iodine staining, the normal epithelium became brown and easier to distinguish normal epithelium from precancerous of premalignant epithelium according to the change of color. Furthermore, normal epithelium slice stained by PAS technique had red reaction but it had no reaction after pretreatment by amylase. However, precancerous and premalignant epithelium tissue slices could not be stained whenever they were pretreated by amylase. The content of glycogen extracted from the esophageal epithelium was lower significantly than those of normal tissue (P < 0.01). But it was no deviation that protein contents of normal esophageal epithelium were compared with carcinoma tissue (P > 0.05). CONCLUSION: These results demonstrated that glycogen and sacchariferous materials in esophageal carcinoma and premalignant lesion tissue decreased significantly and result in light yellow area by iodine staining. It may be helpful for diagnosis of esophageal carcinoma.

Epithelium↗