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 487 records · Page 27Linked to original sources
PubMed1992

Metabolism of arachidonic acid by isolated rabbit ciliary epithelium.

We examined the ability of rabbit ciliary epithelium to metabolize arachidonic acid in vitro. The epithelium was homogenized and incubated with 14C-labeled arachidonic acid. 14C-labeled metabolites were extracted and then separated by thin layer chromatography. The range of arachidonic acid metabolites synthesized by ciliary epithelium was compared to the metabolites generated by rabbit iris-ciliary body. Ciliary epithelium produced substantial amounts of arachidonic acid metabolites that comigrated with 5-HETE and 12-HETE. Authenticity of the 12-HETE produced by ciliary epithelium was confirmed by gas chromatography/mass spectrometry. The ciliary epithelium generated only small amounts of the cyclooxygenase products, PGF2 alpha, PGE2, PGD2 and 6k-PGF1 alpha. In contrast, the iris-ciliary body produced large amounts of cyclooxygenase products such as PGF2 alpha and PGD2. The ability of the ciliary epithelium to generate 12-HETE is noteworthy since 12(R)-HETE is known to be capable of lowering intraocular pressure.

Animals↗
PubMed1994

5 alpha-reductase inhibition by finasteride (Proscar) in epithelium and stroma of human benign prostatic hyperplasia.

Finasteride is a specific 5 alpha-reductase inhibitor that has been shown to reduce the size of human benign prostatic hyperplasia (BPH) by inhibiting the intraprostatic conversion of testosterone to 5 alpha-dihydrotestosterone. The aim of the present in vitro study was to describe in more detail the inhibitory effect of finasteride on 5 alpha-reductase in epithelium and stroma of human BPH. 5 alpha-Reductase activity in epithelium and stroma was inhibited dose-dependently by finasteride. The mean IC50 (50% inhibitory concentration) values, determined in the presence of various testosterone concentrations, were generally 2- to 4-fold lower in epithelium than in stroma. With finasteride concentrations greater than 5 nM, competitive inhibition of 5 alpha-reductase occurred both in epithelium and stroma. The mean inhibition constant Ki[nM +/- SEM] was 7 +/- 3 and 31 +/- 3 in epithelium and stroma, respectively. In the presence of finasteride concentrations < or = 5 nM, the epithelial 5 alpha-reductase seems to be inhibited in an uncompetitive manner, whereas such low finasteride concentrations cause either no inhibition (1-2 nM) or competitive inhibition (5 nM) in stroma. Our present study provides evidence that the inhibitory effect of finasteride on 5 alpha-reductase is much stronger in epithelium than in stroma. Therefore, it is conceivable that the global size-reduction of BPH under finasteride treatment is primarily due to the regression of BPH epithelium.

5-alpha Reductase Inhibitors↗
PubMed1989

Epithelium-derived relaxing factor(s) and bronchial reactivity.

In isolated blood vessels, the mechanical or enzymatic removal of the endothelium augments the contractions evoked by a variety of vasoconstrictor agents, because the endothelial cells release a powerful relaxing substance(s) (endothelium-derived relaxing factor(s]. The focal absence of epithelial cells in airways of patients with asthma is well documented. When the luminal surface of canine bronchi is rubbed gently, the only morphologic change observed is the disappearance of the epithelial cell layer. The removal of the epithelium causes an increased sensitivity of the bronchial smooth muscle to acetylcholine without alteration in the maximal responsiveness to the cholinergic transmitter. The augmentation cannot be attributed to reduced enzymatic breakdown of acetylcholine after removal of the epithelial cells, since it is not affected by inhibitors of acetylcholinesterase. It cannot be attributed to disappearance of a diffusion barrier, since epithelium removal also augments the contractions evoked by electrical stimulation of the cholinergic nerve endings. Removal of the epithelium potentiates the contraction evoked by histamine and 5-hydroxytryptamine in a manner similar to that observed for acetylcholine. The potentiating effect of epithelium removal is more pronounced in larger rather than in smaller bronchi. By contrast, the relaxations evoked by beta-adrenergic agonists are less pronounced in bronchi without, rather than in bronchi with, epithelium. The influence of the epithelium on isoproterenol-induced relaxation is more pronounced in smaller rather than in larger bronchi. These observations suggest that the bronchial epithelium releases an inhibitory factor that partially counteracts activation of the airway smooth muscle by bronchoconstrictor substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Biochemical and histopathological changes in nasal epithelium of rats after 3-day intermittent exposure to formaldehyde and ozone alone or in combination.

To get a better insight into the pathophysiology of the nasal changes induced by formaldehyde-ozone mixtures, a 3-day inhalation study was carried out in rats, using intermittent exposure to formaldehyde (3.6 ppm) and ozone (0.4 ppm) alone or in combination and focusing on biochemical and histopathological changes in rat nasal respiratory epithelium. Formaldehyde dehydrogenase, glutathione S-transferase, glutathione reductase, and glucose-6-phosphate dehydrogenase activities in this epithelium were not affected by the individual compounds. However, combined exposure to formaldehyde and ozone resulted in slightly decreased activities of these enzymes. Formaldehyde was found to induce rhinitis, degeneration, frank necrosis, hyperplasia and squamous metaplasia of the ciliated and non-ciliated nasal respiratory epithelium, while ozone induced disarrangement, flattening and slight basal cell hyperplasia of the non-ciliated cuboidal epithelium accompanied by influx of neutrophils. Proliferating cell nuclear antigen (PCNA) expression was elevated not only in nasal areas showing ozone-induced histopathological changes but also in the otherwise normal-appearing epithelium of the nasal septum. No interactive effects were found with respect to proliferative response of the nasal respiratory epithelium after exposure to the formaldehyde-ozone mixture. The present study did not provide evidence of a major role of glutathione and glutathione-dependent enzymes in the pathogenesis of nasal lesions induced by formaldehyde and/or ozone, demonstrated the potential of ozone to affect the mucociliary epithelium lining the nasal septum, and suggested that PCNA expression is a sensitive tool for detection of early effects of respiratory irritants.

Administration, Inhalation↗
PubMed1990

Epithelium-derived PGE2 inhibits the contractile response to cholinergic stimulation in isolated ferret trachea.

We have previously reported that epithelium-dependent inhibitory factors, both prostanoids and non-prostanoids, can be activated by electrical field stimulation (EFS) and direct nerve stimulation (DNS) in an in vitro nerve-muscle preparation of ferret trachea. In this study we set out to compare the release of the inhibitory prostanoids, PGE2 and PGI2, in preparations with intact and with removed epithelium. Ferret tracheae were mounted in organ baths and phasic contractions were induced by EFS and DNS. The bath concentrations of PGE2 and the PGI2-metabolite 6-keto-PGF1 alpha were measured using radioimmuno assays. The gradual decrease in contractile response to DNS, 2 Hz for 120 min, was 95 +/- 2% of baseline (mean +/- SEM) in preparations with intact epithelium compared with 29 +/- 8% in epithelium-denuded preparations (p less than 0.001). The bath-levels of PGE2 showed a slight but significant (p less than 0.01) increase in denuded preparations with a final bath-concentration at 120 min of 13 +/- 3 pg/ml. The release of PGE2 was more pronounced in preparations with intact epithelium which resulted in a final bath-concentrations of PGE2 of 84 +/- 38 pg/ml which was significantly higher compared with epithelium-denuded preparations and also compared with time-matched controls with the same pattern of contraction induced by DNS alone. The concentrations of 6-keto-PGF1 alpha showed a slight increase which was of comparable magnitude (ns) in intact and denuded preparations. In conclusion this study demonstrates that the cyclooxygenase-dependent component of the epithelium-dependent inhibition of the contractile response to cholinergic nerve stimulation in ferret trachea is mediated by PGE2 but not by PGI2.

6-Ketoprostaglandin F1 alpha↗
PubMed2001

Effect of Ca(2+)-free and Mg(2+)-free BSS Plus solution on the retinal pigment epithelium and retina in rabbits.

PURPOSE: To determine whether intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus (Alcon Laboratory, Fort Worth, Texas) solution alters the adhesiveness between the retinal pigment epithelium and the retina of rabbits. METHODS: Thirty-four eyes of 34 Dutch pigmented rabbits underwent lensectomy and vitrectomy. Subsequently, the vitreous cavity of 24 eyes was irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 10 or 20 minutes. The other 10 eyes were irrigated with BSS Plus solution for 20 minutes as controls. To determine the adhesiveness between the retinal pigment epithelium and retina, a retinal detachment was produced in 12 of the 34 eyes. The apical surface of the retinal pigment epithelium and the photoreceptor outer segments were examined by scanning electron microscopy. Retinal physiology was assessed by electroretinography and retinal morphology by light microscopy. RESULTS: After retinal detachment was produced, the number of cone sheaths on the apical surface of the retinal pigment epithelium after irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes (33 +/- 15, mean +/- SD) was significantly less than the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after irrigation with BSS Plus solution for 20 minutes (120 +/- 50) or the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after 10 minutes of irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution (115 +/- 49; P =.02). The b-wave amplitudes in the eyes irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes were depressed compared with the b-waves in eyes irrigated with BSS Plus solution for 20 minutes on the first postoperative day (P =.03). After the third postoperative day, there was no significant difference in the b-waves (P >.06). Light microscopy demonstrated no morphologic abnormalities after the use of both solutions. CONCLUSIONS: Intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes altered the adhesion between the retinal pigment epithelium microvilli and retinal outer segments and made the creation of retinal detachment less traumatic. These results suggest that Ca(2+)-free and Mg(2+)-free BSS Plus solution may be of clinical value for the creation of an intentional retinal detachment for foveal translocation surgery.

Animals↗
PubMed2003

Immunohistochemical detection of the expression of keratin 14 in the lingual epithelium of rats during the morphogenesis of filiform papillae.

An immunofluorescence study of the expression of keratin 14 (K14) during the formation of filiform papillae was performed and the progress of keratinization of the epithelium of the rat tongue was monitored on semi-ultrathin sections by laser-scanning microscopy. Differential interference contrast (DIC) images were also examined to provide details of histology and cell morphology. No cells with immunoreactivity specific for K14 were detected on the lingual epithelium of foetuses on embryonic days 12 and 16 (E12 and E16), when the lingual epithelium was composed of a single layer or several layers of cuboidal cells. Immunoreactivity specific for K14 was detected first on basal and suprabasal keratinocytes of the dorsal epithelium of the tongue of new-borns on postnatal day 0 (P0) and was conspicuous in juveniles on P14. The immunoreactivity was particularly strong on the basal and suprabasal keratinocytes along the connective tissue papillae. The immunoreactivity extended over the entire cytoplasm but was not detected in the nucleus. The lingual epithelium was composed of stratified squamous cells and the rounded rudiments of filiform papillae were compactly arranged at equal intervals, for the most part, and the spaces between them were narrow and indistinct. Immunostaining of K14 was distinct on basal and suprabasal keratinocytes of the filiform papillar area of tongues of juveniles on P21, when the filiform papillae were conical. The spaces between them were relatively wide and, as a result, interpapillar cell columns were clearly visible. Immunoreactivity specific for K14 in the basal and suprabasal keratinocytes of the interpapillar cell columns was recognizable but was weaker than that in cells of papillar cell columns. The thickness of the epithelium in papillar and interpapillar areas increased gradually with the development of filiform papillae. However, sizes of basal and suprabasal keratinocytes remained almost unchanged during this process. These results suggest that the basal and suprabasal keratinocytes of the filiform papillar area proliferate with the initiation of the morphogenesis of filiform papillae and the keratinization of the epithelium. In addition, it appears that, after P14, the basal and suprabasal keratinocytes of the interpapillar area proliferate to supply the keratinocytes of the expanding interpapillar regions.

Animals↗
PubMed1989

Active transport of ascorbic acid into lens epithelium of the rat.

The transport rates of radiolabeled ascorbic acid (AA) and dehydroascorbic acid, as well as 3-O-methyl-D-glucose and L-glucose from blood into aqueous humor, lens epithelium and lens 'cortex' compartments were studied in male Sprague-Dawley rats. In vivo pulse chase kinetic studies and modeling of transport from plasma and aqueous and on into idealized water compartments of lens epithelium and cortex allowed for the calculation of transport rate constants, Ki (min-1), in experiments utilizing L-glucose as a passive internal control. TLC chromatography was used to monitor intraocular labeled molecules deriving from labeled test molecules introduced via blood. Results indicate that AA enters aqueous humor at rates similar to L-glucose and likely via simple passive diffusion. In contrast, an active uptake of AA by lens epithelium was found with the calculated entry constant for ascorbate being more than 21 times faster than that of L-glucose. Concentrations in lens epithelium were found to be more than twice that of aqueous humor within only 7 min from the introduction of a [14C]AA bolus into blood. It was also found that very little AA continued on past the epithelium to the interior lens cortex compartment. Our data suggest no special uptake of AA by lens fiber cells. The non-metabolizable analog of D-glucose, 3-O-methyl-D-glucose, however, readily moves past the lens epithelium into fiber cells at much faster rates than the passive L-glucose marker and in a manner consistent with facilitated diffusion. The data suggest that even in a nocturnal species, such as a rat, which demonstrates relatively low circulating levels of ascorbic acid in plasma and aqueous humor, special mechanisms exist for moving ascorbic acid into intraocular tissues. More specifically, the lens epithelium actively takes up ascorbate for some, as yet unclear purpose while the interior fiber cells appear to have no special uptake mechanism for this molecule.

Animals↗
PubMed2002

Contractile responses of the rat vas deferens after epithelium removal.

The purpose of the present investigation was to verify the role of the epithelium in the functional response of the rat vas deferens. Our results showed that the contractile effect of cumulative doses of clonidine (3.10(-5)-3.10(-3)) was increased after the removal of the epithelium. The effect of clonidine in epithelium-free vas deferens returned to normal values when an isolated epithelium from another vas deferens was added to the organ bath, showing that the epithelium is responsible for this increase of maximum effect for clonidine. Drugs functionally or structurally related to clonidine, such as oxymetazoline, alpha-methylnorepinephrine and moxonidine, did not have their dose-response curves altered. The curves for other contractile agents, such as noradrenaline, acetylcholine, ATP, 5HT, bradykinin and histamine, or the relaxation induced by isoprenaline and forskolin were also not modified. Electrically-induced contractions at frequencies from 0.1 to 20 Hz and the mechanism of negative feed-back, brought about by clonidine (10(-10)-10(-8) M) through pre-synaptic alpha2-adrenoceptors, were not changed after the removal of epithelium. In conclusion, a significant function of the epithelium in the contractility of the rat vas deferens was demonstrated for clonidine, but not for other agonists.

Acetylcholine↗
PubMed2001

In vitro modulation of steroid 5alpha-reductase activity by phospholipases in epithelium and stroma of human benign prostatic hyperplasia.

Membrane components, such as phospholipids, play an important role in the regulation of prostatic 5alpha-reductase activity. To describe in more detail the impact of such regulation on 5alpha-reductase activity, epithelial and stromal cell homogenates of human BPH were treated with phospholipases to specifically alter the structure of cellular phospholipid components. Phospholipase A(2) (PLA(2)) was used to alter the structure of the nonpolar, hydrophobic region of the membrane bilayer. Various types of phospholipase C (PLC) affect the polar, hydrophilic region of phospholipids. In epithelium and stroma, 5alpha-reductase activity was dose-dependently inhibited by PLA(2) and PLC type III. In epithelium and stroma, the mean IC(50) values of PLA(2) were 9.4 +/- 1.1 and 13.9 +/- 2.6 [U/mg protein +/- SEM], respectively. The mean IC(50) values of PLC type III in epithelium and stroma were 4.5 +/- 1.2 and 1.7 +/- 0.2 [U/mg protein +/- SEM], respectively. In epithelium as well as in stroma, 5alpha-reductase activity was more greatly inhibited by PLC type III than by PLA(2). Both in epithelium and stroma, PLA(2) significantly decreased the V(max) of 5alpha-reductase whereas its K(m) remained unaffected. A similar decrease in V(max) was found with PLC type III in epithelium and stroma. Furthermore, the K(m) of epithelial 5alpha-reductase increased significantly following the addition of PLC type III. The two phospholipases, with their specific substrate affinities and sites of hydrolysis, exhibited significantly different effects on 5alpha-reductase, indicating that 5alpha-reductase activity is not unspecifically affected by modification of the hydrophilic milieu. Rather, 5alpha-reductase activity is specifically modulated by various phospholipids and/or phospholipolysis mediated degradation products. These findings suggest that the structural composition of the lipid environment plays a fundamental role in the post-translational regulation of 5alpha-reductase activity in the epithelium and stroma of human BPH. Thus, changes in membrane phospholipid content seem to be instrumental in the expression of DHT-dependent processes.

Epithelium↗
PubMedDate not supplied

Kinetic analysis of androstenedione 5 alpha-reductase in epithelium and stroma of human prostate.

In the human prostate, various androgen-metabolizing enzymes are present. Among these enzymes, testosterone 5 alpha-reductase seems to be dominant. However, androstenedione is also a potential substrate of the prostatic 5 alpha-reductase. To address the question of to what extent the reduction of androstenedione to androstanedione occurs, the present study describes in detail the kinetic characteristics (Km and Vmax) and possible age-dependent alterations of this enzymatic step in epithelium and stroma of the human prostate. In normal prostate (NPR), the mean Km (nM) and Vmax (pmol/mg protein.h) were about twofold higher in stroma (Km, 211; Vmax, 130) than in epithelium (Km, 120; Vmax, 56), whereas in the benign prostatic hyperplasia (BPH), the mean Km (nM; mean +/- SEM) and Vmax (pmol/mg protein.h; mean +/- SEM) were about sixfold higher in stroma (Km, 668 +/- 121; Vmax, 415 +/- 73) than in epithelium (Km, 120 +/- 10; Vmax, 73 +/- 8). In BPH, those differences between epithelium and stroma were highly significant (p < 0.001). However, the efficiency ratios (Vmax/Km) of neither BPH nor NPR showed any significant differences between epithelium (NPR, 0.47; BPH, 0.62 +/- 0.06) and stroma (NPR, 0.70; BPH, 0.63 +/- 0.05). With respect to age-related changes, only stroma showed a significant increase of Km (p < 0.01) and Vmax (p < 0.05) with age. In summary, in both epithelium and stroma of the human prostate, a 5 alpha-reductase converts in measurable amounts androstenedione to androstanedione. The kinetic data were, in part, different between epithelium and stroma; the reason for this difference remains unclear. In comparison to other metabolic conversions, such as testosterone to dihydrotestosterone and androstenedione to testosterone, it is unlikely that, in the human prostate, the adrenal androgen androstenedione contributes significantly to the formation of testosterone and, further, of dihydrotestosterone.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2003

Expression of two membrane fusion proteins, synaptosome-associated protein of 25 kDa and vesicle-associated membrane protein, in choroid plexus epithelium.

In addition to being the major site of cerebrospinal fluid formation, the choroid plexus epithelium emerges as an important source of polypeptides in the brain. Physiologically regulated release of some polypeptides synthesized by the choroid plexus has been shown. The molecular mechanisms underlying this polypeptide secretion have not been characterized, however. In the present study, synaptosome-associated protein of 25 kDa and vesicle-associated membrane protein, two membrane fusion proteins playing a critical role in exocytosis in neurons and endocrine cells, were found to be expressed in the choroid plexus epithelium. It was also shown that in choroidal epithelium, synaptosome-associated protein of 25 kDa and vesicle-associated membrane protein stably interact. Two members of the vesicle-associated membrane protein family, vesicle-associated membrane protein-1 and vesicle-associated membrane protein-2, were expressed in the rat choroid plexus at the messenger RNA and protein level. However, their newly discovered isoforms, vesicle-associated membrane protein-1b and vesicle-associated membrane protein-2b, produced by alternative RNA splicing, were not detected in choroidal tissue. Immunohistochemistry demonstrated that vesicle-associated membrane protein is confined to the cytoplasm of choroidal epithelium, whereas synaptosome-associated protein of 25 kDa is associated with plasma membranes, albeit with a varied cellular distribution among species studied. Specifically, in the rat choroid plexus, synaptosome-associated protein of 25 kDa was localized to the basolateral membrane domain of choroidal epithelium and was expressed in small groups of cells. In comparison, in ovine and human choroidal tissues, apical staining for synaptosome-associated protein of 25 kDa was found in the majority of epithelial cells. These species-related differences in cellular synaptosome-associated protein of 25 kDa distribution suggested that the synaptosome-associated protein of 25 kDa homologue, synaptosome-associated protein of 23 kDa, is also expressed in the rat choroid plexus, which was confirmed by reverse-transcriptase polymerase chain reaction. Our findings suggest that synaptosome-associated protein of 25 kDa and vesicle-associated membrane protein are involved in secretion of polypeptides from the choroid plexus epithelium. The presence of synaptosome-associated protein of 25 kDa and its homologue as well as multiple isoforms of vesicle-associated membrane protein in choroidal epithelium may play a role in the apical versus basolateral targeting of secretory vesicles.

Animals↗
PubMed1980

Changes in the differentiation pattern of oral mucosal epithelium following heterotopic connective tissue transplantation in man.

Anterior palatal connective tissue was transplanted into wound beds created within the alveolar mucosa of the lower anterior vestibulum in seven adults females. Six months postoperatively, the epithelial lining of the inverted transplants was biopsied and compared histologically, histometrically, and stereologically to the neighboring mucosal epithelium. The data suggest that (1) connective tissue of the lamina propria is primarily responsible for the structural specificity of the overlying epithelium, (2) inductive stimuli are not confined to superficial layers but also originate from deep portions of the lamina propria, (3) these stimuli influence both the epithelial differentiation and the type of epithelium-connective tissue interface, and (4) the epithelial response to the inductive stimuli in man may depend on the individual type of epithelial differentiation pattern originally prevailing at the recipient site. The transplant-lining epithelium assumed features resembling that of the hard palate in subjects with an alveolar mucosal epithelium with cheek-type characteristics. In subjects with an alveolar epithelium displaying a mixed differentiation pattern, the transplant-lining epithelium continued to generate a mixed pattern or else shifted to more palate-like characteristics.

Adult↗
PubMed1992

Fine structure of the dorsal lingual epithelium of the crab-eating monkey, Macaca irus.

Light and electron microscopic observations of the dorsal lingual epithelium of the crab-eating monkey, Macaca irus, revealed three different regions: the epithelium on the anterior side of the filiform papillae, the epithelium on the posterior side of the filiform papillae, and the interpapillar epithelium. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules appear predominantly in the intermediate layer of the epithelium on the anterior side of filiform papillae. In the epithelium on the posterior side of the filiform papillae, no keratohyalin granules are seen and, instead, tonofibrils are prominent. The cells begin to be significantly flattened. In the interpapillar epithelium, no keratohyalin granules and tonofibrils are seen, and the tonofilaments occupy almost the entire cytoplasm of the cells of the intermediate and surface layers, with the cells having larger volumes in these layers.

Animals↗
PubMed1996

Transplantation of cultured mucosal epithelium: an experimental study.

We investigated morphological changes after transplantation of cultured mucosal epithelium using a modified Barrandon's method (1988). Serially cultivated human mucosal epithelium was transplanted onto the reverse side of rectangular dorsal skin flaps in hairless mice. The morphological changes in the epithelium were studied using paraffin sections. The modified Barrandon's method used in this study has advantages such as minimum external trauma and less chance of infection. The cultured epithelium was taken within 1 week and gradually increased its epithelial thickness. Keratinized epithelium arises after 3 weeks. At 4 weeks after grafting, the grafted epithelium comprised 7-10 cell layers. The structure of transplanted tissue, in conjunction with surrounding connective tissues, showed dermis-like features at day 7 after transplantation. From these results, it was confirmed that cultured mucosal epithelium could be successfully transplanted and its morphology was similar to that of normal mucosal tissue.

Animals↗
PubMed1999

Airway epithelium of transplanted lungs with and without direct bronchial artery revascularization.

OBJECTIVE: Normal systemic blood flow to the airways and lung parenchyma of transplanted lungs can only be re-established by direct bronchial artery revascularization. The purpose of the present study was to investigate whether such direct bronchial artery revascularization would preserve ciliary function, previously shown to be reduced in lungs transplanted without revascularization. METHODS: Twenty-five single lung transplanted patients were included in this study. Complete direct bronchial artery revascularization was achieved in eight patients. In 16 patients the procedure had either failed (n = 10) or was not attempted (n = 6). In one patient the result of the revascularization was unknown. Airway epithelium samples were obtained from the native and the transplanted lungs during bronchoscopic examinations. Airway erythema and excessive secretion were registered. The epithelium samples underwent histological examination and ciliary beat frequency was measured in vitro by video recording. Transbronchial biopsies from the transplanted lungs were examined for signs of rejection and bronchitis. RESULTS: No differences in ciliary beat frequency nor in the distribution of ciliated/de-ciliated columnar epithelium cells between native lungs and transplanted lungs with or without successful direct bronchial artery revascularization could be demonstrated. In 38% of the transplanted lungs without successful revascularization metaplastic or squamous epithelium was present, while lungs with successful revascularization had only normal columnar epithelium. Ongoing rejection or airway erythema did not influence ciliary beat frequency. Excessive secretion in the airways was the only finding associated with significantly increased ciliary beat frequency. CONCLUSIONS: Ciliary beat frequency of epithelium cells of transplanted lungs did not differ from that of native lungs and consequently direct bronchial artery revascularization did not have any demonstrable important influence. Excessive secretion in the airways was associated with increased ciliary beat frequency. The histological findings also showed that the abundance of ciliated cells was preserved in transplanted bronchi irrespective of bronchial artery revascularization. However, epithelium metaplasia was only seen in transplanted bronchi without revascularization.

Angiography↗
PubMed1993

Glutathione and glutathione S-transferases in Barrett's epithelium.

Glutathione content, enzyme activity and isoenzyme composition of glutathione S-transferases were assayed in normal and Barrett's esophageal epithelium of ten patients with Barrett's esophagus. In addition, gastric and duodenal specimens from the same patients were also investigated. Glutathione content, glutathione S-transferase enzyme activity as well as glutathione S-transferase pi content were all significantly lower in Barrett's epithelium as compared to normal esophageal mucosa. In contrast, glutathione S-transferase class alpha enzymes are markedly expressed in Barrett's epithelium, whereas only low amounts are present in normal esophageal epithelium. Glutathione and glutathione S-transferase composition in Barrett's epithelium show striking similarities with gastric epithelium, whereas duodenal epithelium is provided with considerable higher amounts of glutathione and glutathione S-transferases, except for levels of glutathione S-transferase class pi, which are lower. A significant negative correlation exists between glutathione S-transferase enzyme activity in the mucosa along the gastrointestinal tract, and the tumour incidence. Since glutathione and glutathione S-transferase are correlated with protection against cellular or cytogenetic damage, the low content of glutathione and glutathione S-transferases in the Barrett's esophagus may be a factor of relevance for the increased tumour risk in this tissue.

Adult↗
PubMed1997

Degradation of bradykinin by bovine tracheal epithelium and isolated epithelial cells.

1. The degradation of bradykinin (BK) labelled with tritiated proline at positions 2 and 3 ([3H]-BK) was determined on the luminal surface of bovine tracheal epithelium, in supernatants obtained from incubations of the luminal tracheal surface, and in suspensions of isolated tracheal epithelial cells. Peptidase inhibitors and identification of peptide fragments were used for characterization of the metabolic pathways. 2. On the luminal surface of intact bovine trachea, [3H]-BK was degraded with a half life of 12.8 min. [1-7]-BK and [1-5]-BK were the major direct metabolites which were further degraded via [1-3]-BK and [2-3]-BK to proline. Metabolism of [3H]-BK was unaltered in the presence of ramiprilat (250 nM) or phosphoramidon (10 microM). Phenanthroline diminished the formation of [1-7]- and [1-5]-BK and abolished the generation of proline. 3. Supernatants obtained from incubations of tracheal epithelium contained kininase activities which steadily increased when tracheae were incubated for longer than 30 min. After 60 min contact with epithelium, the incubation medium contained higher kininase activities than the epithelium itself. The spectrum of kinin metabolites generated by kininases in the supernatant was comparable to that formed by intact epithelium. 4. In suspensions of isolated epithelial cells, [3H]-BK was degraded with a half life of 70 min. The metabolites [1-3]- and [2-3]-BK were formed in parallel to [1-7]- and [1-5]-BK; however, proline was not generated. Degradation of [3H]-BK was not influenced by ramiprilat, but was inhibited by 85% in the presence of phosphoramidon. Phosporamidon markedly inhibited the generation of [1-7]- and [1-5]-BK and nearly abolished the formation of [1-3]- and [2-3]-BK. 5. In conclusion, angiotensin I-converting enzyme and neutral endopeptidase 24.11 are not significantly involved in [3H]-BK degradation on the luminal side of intact tracheal epithelium. The spectrum of metabolites found may in fact reflect the combined activities of metalloendopeptidase 24.15 and post-proline cleaving enzymes. Enzymes showing similar kininase activities are also released from the epithelium. Isolated epithelial cells contain low activities of these kininases, but a high activity of neutral endopeptidases, which may reflect an exclusively basolateral localization of the latter.

Animals↗