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At least 91 records · Page 5Linked to original sources
PubMed1986

Remodelling of the retinal pigment epithelium in response to intraepithelial capillaries: evidence that capillaries influence the polarity of epithelium.

Light- and urethane-induced retinopathies in rats are characterized by loss of photoreceptors. Retinal capillaries subsequently become incorporated into the normally avascular retinal pigment epithelium. These models provided an opportunity to study the response of epithelial cells to closely apposed capillaries, in order to determine if capillaries contribute to the polar organization of epithelial cells. Pigment epithelial cells reorganized their lateral plasma membrane where the latter faced intraepithelial capillaries. This normally flat, undifferentiated membrane developed attachment sites, folds and intracytoplasmic tubules, and exhibited endocytosis and putative basal lamina secretion. These structural and functional specializations are normally restricted to the basal plasma membrane - the normal vascular front of the cell facing the dense meshwork of capillaries constituting the choriocapillaris. We conclude that RPE cells, and perhaps epithelia in general, polarize in response to an adjacent capillary bed.

Animals↗
PubMed1975

Retinal pigment epithelium dystrophy in central serous detachment of sensory epithelium.

The incidence of central serous neuro-epithelial detachment in the polulation living in the health district Prague-10 was found to be one in 22,000 inhabitants a year. The cases were classified into three types: A. Inkblot diffusion 60%; B. upward diffusion 25%; C. congregation type 15%. The site of leakage was usually in the upper part of the detached retina or slightly below the horizontal line. Relapses were observed in 16 out of 79 patients, 20%, usually stemming from the original leak. The average re-attachment time was 98 days. In 10% a chronic course led to extensive dystrophy of the pigment epithelium.

Adult↗
PubMed1986

Lectin-binding affinities of the epithelium in the respiratory tract. A light microscopical study of ciliated epithelium in rat, guinea pig, and hamster.

Complex carbohydrate components of surface coat and secretory granules were investigated in the laryngo-tracheo-bronchial epithelium of 3 laboratory animals (rat, guinea pig, and Syrian hamster). 2 groups of epithelial cells were distinguished in the light microscope: ciliated cells and non-ciliated cells. The latter mainly represent secretory cells and are subdivided into serous and mucous secretory cells. Apical glycocalix: In the rat, ciliated cells possess a significant number of Con A, RCA I, and WGA receptors, and a smaller number of UEA I binding sites. In hamsters and in guinea pigs additional binding sites for HPA could be demonstrated. The apical glycocalix of the non-ciliated cells in the rat evince marked staining with RCA I, WGA, and HPA, and less intensive binding of UEA I. In guinea pigs and in hamsters, the presence of additional Con A receptors was noted. Basolateral glycocalix: The basolateral surface coat of ciliated and non-ciliated cells shows identical lectin binding affinities. In the rat, the basolateral glycocalix binds RCA I; in the guinea pig, in addition, positive staining with UEA I and HPA is observed; in the hamster, the basolateral surface coat is outlined by RCA I and HPA receptors. Secretory products: Secretory granules of mucous cells in the rat react with Con A, UEA I and HPA lectins. In guinea pigs, these substances also bind RCA I and WGA lectins. Mucous granules in the secretory cells of the hamster are positive for Con A, RCA I, and HPA lectins. Granules of non-ciliated serous cells of rats bind Con A, UEA I, and HPA lectins. In the guinea pig, this reaction is weaker for UEA I lectin but comparable for Con A and HPA binding. A positive reaction with RCA I lectin only is found in the serous secretory granules of the hamster.

Alcian Blue↗
PubMed1999

Quantitative particle-induced X-ray emission imaging of rat olfactory epithelium applied to the permeability of rat epithelium to inhaled aluminum.

Neurotoxicity from chronic metal inhalation has been suggested as an underlying contributor to late-developing neurodegenerative diseases that have symptoms similar to Alzheimer's and Parkinson's syndromes. If inhaled metals contribute to pathogenesis of these diseases, identifying, localizing, and quantitating metal deposition(s) within specific target regions of the central nervous system will be critical to our understanding of the mechanisms. Standard analytical techniques used to date require exposure to extremely high concentrations of metals to meet analytical detection limits in small tissue areas. The relevance to lower-dose environmentally relevant exposures and potential protective barriers is therefore questionable. The feasibility of microbeam particle-induced X-ray emission is investigated as a method for rapidly scanning tissues to study the inhalation of metals, nasal permeability, and central nervous system deposition. The optimal beam spot and analysis time used to image the rat olfactory epithelium to facilitate the rapid detection of aluminum localizations were determined. Measurements of aluminum localizations in rat olfactory bulb and brain sections are also presented.

Administration, Inhalation↗
PubMed1995

Lymphocytes selected in allogeneic thymic epithelium mediate dominant tolerance toward tissue grafts of the thymic epithelium haplotype.

Athymic mice grafted at birth with allogeneic thymic epithelium (TE) from day 10 embryos before hematopoietic cell colonization reconstitute normal numbers of T cells and exhibit full life-long tolerance to skin grafts of the TE haplotype. Intravenous transfers of splenic cells, from these animals to adult syngeneic athymic recipients, reconstitute T-cell compartments and the ability to reject third-party skin grafts. The transfer of specific tolerance to skin grafts of the TE donor strain, however, is not observed in all reconstituted recipients, and the fraction of nontolerant recipients increases with decreasing numbers of cells transferred. Furthermore, transfers of high numbers of total or CD4+ T cells from TE chimeras to T-cell receptor-anti-H-Y antigen transgenic immunocompetent syngeneic hosts specifically hinder the rejection of skin grafts of the TE haplotype that normally occurs in such recipients. These observations demonstrate (i) that mice tolerized by allogeneic TE and bearing healthy skin grafts harbor peripheral immunocompetent T cells capable of rejecting this very same graft; and (ii) that TE selects for regulatory T cells that can inhibit effector activities of graft-reactive cells.

Animals↗
PubMed1984

Circadian-stage dependence of methotrexate in a keratinized epithelium. An in-vivo study using flow cytometry on the hamster cheek pouch epithelium.

The partially synchronized cell system of the hamster cheek pouch epithelium shows a characteristic diurnal rhythm of cell proliferation. Bolus injections of methotrexate (Mtx) in both lethal (10 g/m2) and non-lethal (2 g/m2) doses were found to inhibit cell-cycle progression primarily by impairing the G1/S transition. The results were obtained by flow cytometric DNA analysis. The inhibitory effect of Mtx manifested itself as a relative decrease of the S fraction (drug-effector phase), and was found to be dependent both on the dose and on the time of the day it was given. A bolus injection of Mtx was given either at 1200 hr (when a minimal number of cells are in S phase) or at 0200 hr (when a maximum number of cells are in S phase). The greatest cumulative decrease in S fraction was seen when the injection was given at 1200 hr. The time between injection and the effect (seen as a decrease in S fraction) was independent of the time of the Mtx injection, but seemed instead to be related to the natural diurnal period of increasing flux from G1 to S phase (at the onset of the dark period). The main effect (the relative decrease in S fraction) was repeated during the following 24-hr period, pointing to a protracted effect of Mtx on G1 cells. G1 cells affected by the initial high Mtx plasma concentration seem to be responsible for the reduced influx into S phase in both the first and second 24-hr period. In earlier toxicological studies, the survival rate of hamsters was dependent on the time of injection and was highest after injection at 1200 hr. Thus maximum cytokinetic effect on epithelial cells was found at the time of the day when there was a minimum lethal effect on the animal.

Animals↗
PubMed1990

Regulation of sympathetic and parasympathetic receptor responses in the rat trachea by epithelium: influence of mechanical and chemical removal of epithelium.

Removal of the epithelial layer of rat tracheal tissue did not affect the methacholine-induced contraction of the tracheal smooth muscle, but attenuated the (-)-isoprenaline induced relaxation (expressed as percentage of the methacholine contraction). In this way the epithelial layer seemed to play a role in the maintenance of an autonomic balance between sympathetic and parasympathetic receptor responses. Incubation of rat tracheal tissue with cumene hydroperoxide (3 x 10(-5)-10(-3) M) resulted in a dose-dependent destruction and (partial) removal of the epithelial layer. Cumene hydroperoxide diminished muscarinic receptor responses of the rat trachea. Moreover, the autonomic balance between muscarinic and beta-adrenoceptor responses was affected. The effects of cumene hydroperoxide on receptor responses were more pronounced after epithelium removal. The protective role of the epithelial layer of pulmonary tissue against oxidative stress has therefore been emphasized.

Animals↗
PubMed1991

A comparison of aminopeptidases from excised human buccal epithelium and primary cultures of hamster pouch buccal epithelium.

Aminopeptidase activity associated with human buccal tissue and primary cultures of hamster buccal epithelium homogenates was assayed fluorometrically using 4-methoxy-2-naphthylamides of leucine, alanine, and arginine. Kinetic parameters, Km and Vmax, for all substrates were estimated. Aminopeptidase parameters for human tissue were similar to those for the in-vitro system and reported literature values for rodent buccal tissue aminopeptidases. Aminopeptidases of both tissues were also found to be similarly sensitive to typical inhibitors, bestatin and puromycin. Overall results suggest that appropriate in-vitro systems derived from animal tissues may be useful in assessing the role and localization of peptidases associated with buccal tissue.

2-Naphthylamine↗
PubMed1983

Intracellular chloride activities in canine tracheal epithelium. Direct evidence for sodium-coupled intracellular chloride accumulation in a chloride-secreting epithelium.

Canine tracheal epithelium secretes Cl via an electrogenic transport process that appears to apply to a wide variety of secretory epithelia. To examine the mechanisms involved, intracellular chloride activity, acCl, was measured with Cl-selective intracellular microelectrodes. The results indicate that when the rate of secretion was minimal acCl was 37 mM; with stimulation of secretion the intracellular voltage depolarized, but acCl was not significantly altered, at 39 mM. These findings indicate that: (a) Cl is accumulated across the basolateral membrane under nonsecreting and secreting conditions at an activity 3.8 and 2.4 times, respectively, that predicted for an equilibrium distribution; (b) Cl exit across the apical membrane may be passive with an electrochemical driving force of 22 mV; and (c) stimulation of secretion enhanced the rate of Cl entry across the basolateral membrane, since Cl transport increased without a change in acCl. In the absence of Na in the extracellular fluid, acCl approached the value expected for an equilibrium distribution. This finding suggests that "uphill" entry of Cl into the cell against its electrochemical gradient is dependent upon, and energized by, the entry of Na down its gradient. Submucosal bumetanide, a loop diuretic, also decreased the rate of Cl secretion and decreased acCl, indicating an inhibition of Cl entry. These findings indicate that Cl entry into the cell is directed against its electrochemical gradient and is mediated by a Na-coupled, bumetanide-inhibitable, transport process at the basolateral membrane and that Cl may exit passively down a favorable electrochemical gradient across the apical membrane.

Animals↗
PubMed1994

Generation of a murine monoclonal antibody to normal mammary epithelium using mice rendered immune-tolerant to malignant mammary epithelium.

A monoclonal antibody (MAb) that distinguishes normal from malignant mammary epithelia in tissue or cell lines was generated using a procedure that involved immune-tolerization before immunization. Immune-tolerance to two transformed mammary epithelial cell lines (MCF.7 and MDA.MB.231 cell lines combined) was induced in neonatal mice within 24 hr of birth. Successful induction of immune-tolerance was determined by an indirect immunohistological method, testing sera from mice against the tolerogen (i.e., the MCF.7 and MDA.MB.231 cell lines). Mice lacking antibodies in their sera against the immune-tolerogen were subsequently immunized with an extract of normal breast epithelium. One mouse was selected for hybridoma production based on evidence of serum antibody that showed reactivity with normal mammary epithelial cells (MEC) but not with invasive breast carcinoma cells, as determined by an indirect immunohistological method. Spleen cells from the selected mouse were fused with a mouse myeloma cell line to generate MAb. After extensive screening, one MAb was further studied on the basis of reactivity with normal MEC in tissue and absence of staining of malignant MEC in tissue or tumorigenic MEC lines. This test of specificity of reactivity revealed that the antigen detected by the specific antibody was expressed on the apical plasma membrane of normal glandular epithelia that included breast, cervix, colon, lung, pancreas, and stomach, but not on their malignant counterparts in tissue sections. The antigen recognized by the MAb was termed luminal epithelial antigen with an apparent MW of 92 KD (LEA.92). This study illustrates the practical usefulness of the immune-tolerization/immunization approach in the generation of antibodies with particular specificity requirements, as in the identification of an antigen that is differentially expressed in two tissues (e.g., normal and malignant) which otherwise have a multiplicity of antigens in common.

Adult↗
PubMed1990

Allergens of horse epithelium. I. Physicochemical and immunochemical characterization of five different horse epithelium raw materials used for allergen extract preparation.

We investigated five horse epithelial allergen extracts prepared from different qualities of raw material by several biochemical and immunochemical methods. Horse serum albumin and horse serum were used to identify serum-related antigens. We found high similarities as well as marked differences between the extracts. There were strong differences in the protein contents, the protein patterns obtained by isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis, the total allergenic activities obtained by radioallergosorbent test inhibition assays and the amounts and numbers of serum-related proteins. The patterns of dander-related allergens in crossed radioimmunoelectrophoresis were similar but showed partly strong differences in allergen concentrations. Allergen compositions determined by blotting methods showed only minor differences between the investigated epithelial extracts. It appears that some of the differences, e.g. the content of serum-related proteins, depend on the way the different raw materials are prepared. Because serum-related extract components are not considered as major allergens, their content should be low in horse epithelial allergen extracts. For this reason whole skin cannot be recommended as starting material for horse epithelium allergen extract preparation.

Allergens↗
PubMed1987

Response of the macaque nasal epithelium to ambient levels of ozone. A morphologic and morphometric study of the transitional and respiratory epithelium.

Although ozone (O3)-induced bronchiolitis has been morphologically characterized, effects of O3 on the upper respiratory tract have not been thoroughly investigated. The purpose of this study was to determine whether exposures to ambient levels of O3 induce lesions in the nasal mucosa. Bonnet monkeys were exposed to 0.00, 0.15, or 0.30 ppm O3 for 6 or 90 days, 8 hours/day. After exposure, nasal mucosa was processed for light and electron microscopy. Quantitative changes were evident in the nasal transitional and respiratory epithelium. At 6 or 90 days of exposure to 0.15 or 0.30 ppm O3 lesions consisted of ciliated cell necrosis, shortened cilia, and secretory cell hyperplasia. Inflammatory cell influx was only present at 6 days of exposure. Ultrastructural changes in goblet cells were evident at 90 days. Ambient levels of O3 can induce significant nasal epithelial lesions, which may compromise upper respiratory defense mechanisms.

Animals↗
PubMed1996

[Three-dimensional structures of the nonpigmented epithelium of the dog ciliary body--application of sodium hydroxide digestion to scanning electron microscopic observation of the ciliary epithelium].

The nonpigmented epithelium (NPE) of the dog ciliary body was three-dimensionally observed by scanning electron microscopy (SEM) using sodium hydroxide digestion. The inner limiting membrane of the NPE and the zonular fibers covering the NPE were completely dissolved in 6N sodium hydroxide for 10-15 minutes at 60 degrees C, although the surface structures of the plasma membrane were remarkably preserved despite the rather rigorous treatment. Thus, the entire surface of the NPE was exposed for SEM. The surface of the NPE at the anterior part of the pars plicata was flat, but many complex processes were observed in the surfaces of the NPE as lateral walls of the middle and posterior parts of the pars plicata, to which the zonular fibers had adhered. The processes were more prominent in the middle portion and gradually flattened near the posterior portion. Many pit-like structures and drumstick-like processes of the plasma membrane were localized at the apex of the ciliary process.

Animals↗
PubMed2006

[Bilateral serous detachment of the neurosensory retina and retinal pigment epithelium with rip of the peripheral pigment epithelium].

HISTORY: A 52-year-old patient with atypical plasmocytoma presented with a bilateral serous detachment of the retina as well as a huge detachment of the pigment epithelium (PE) in the periphery. Shortly thereafter the PE ruptured. In the left eye this led to substantial central macular fibrosis. DIAGNOSIS: The clinically healthy patient showed a nephrotic syndrome; neither typical monoclonality was detectable nor was erythropoiesis or myelopoiesis reduced. THERAPY: To avoid further reduction of VA pars plana vitrectomy (ppV) with silicone oil tamponade and laser coagulation was performed. Clinical findings were reduced significantly and VA was stabilized for 2.5 years. DISCUSSION: PE detachments and serous retinal detachments in patients with nephrotic syndrome are only mentioned in a few cases. However, a peripheral rupture of the PE to this extent seems to be very rare. Early ppV with silicone oil and laser coagulation may prevent further macular fibrosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Effects of formaldehyde on the frog's mucociliary epithelium as a surrogate to evaluate air pollution effects on the respiratory epithelium.

The increasing use of alcohol as an alternative fuel to gasoline or diesel can increase emission of formaldehyde, an organic gas that is irritant to the mucous membranes. The respiratory system is the major target of air pollutants and its major defense mechanism depends on the continuous activity of the cilia and the resulting constant transportation of mucous secretion. The present study was designed to evaluate the effects of formaldehyde on the ciliated epithelium through a relative large dose range around the threshold limit value adopted by the Brazilian legislation, namely 1.6 ppm (1.25 to 5 ppm). For this purpose, the isolated frog palate preparation was used as the target of toxic injury. Four groups of frog palates were exposed to diluted Ringer solution (control, N = 8) and formaldehyde diluted in Ringer solution at three different concentrations (1.25, 2.5 and 5.0 ppm, N = 10 for each group). Mucociliary clearance and ciliary beat frequency decreased significantly in contact with formaldehyde at the concentrations of 2.5 and 5.0 ppm after 60 min of exposure (P<0.05). We conclude that relatively low concentrations of formaldehyde, which is even below the Brazilian threshold limit value, are sufficient to cause short-term mucociliary impairment.

Air Pollutants↗
PubMed1985

Circadian variation in mitotic influx in a keratinized epithelium. The stathmokinetic technique used in vivo on the hamster cheek pouch epithelium and analyzed by periodic regression analysis.

An in vivo study of the hamster cheek pouch epithelium using the stathmokinetic technique (Colcemid) demonstrated a circadian variation in mitotic influx. Based on measurements of all nucleated epithelial cells the diurnal mean was estimated in two separate experiments as 0.34%/h +/- 0.02 (SE) and 0.27%/h +/- 0.02 (SE) respectively. 3HTdR was injected in the latter study (a double labelling experiment). The significant difference between the two experiments is, however, probably due to biological variations. The maximal values for the mitotic rate were found during the light (resting) period, as were the maximal values for the mitotic index. The mean mitotic influx for the 'light period' was estimated as 0.5-0.4%/h, and for the 'dark period' as 0.2%/h. Independent analyses demonstrated the necessity of a circadian-dependent correction of the 1 and 4 h values of accumulated metaphases. The 1 h value was significantly too high during the light as well as the dark period. The 4 h value was found to be too low, but only significantly so during the dark period. Basing the estimation of mitotic rate on the 3 h accumulation value produced only very similar results to those found by using all four accumulation periods. The use of overlapping experiments proved that only cells entering mitosis after Colcemid application were arrested, so that when arrested metaphases were counted the accumulation line was correctly drawn through the origin. In the latter study (the double labelling experiment) both S- (Møller and Keiding 1982) and mitotic influx were estimated, the estimates being 0.55%/h +/- 0.03 (SE) and 0.27%/h +/- 0.02 (SE) respectively. Even considering possible methodological problems, the discrepancy between the S efflux and the mitotic influx indicates cell death and/or differentiation from G2.

Anaphase↗
PubMedDate not supplied

[Radiobiology of stem cells in intestinal epithelium. Effect of single and multiple preliminary sublethal irradiation of mice on the dose dependence of the survival of stem cells in small intestine epithelium].

After a single or three-fold whole body irradiation of mice with a dose of 4 Gy and the time interval for the proliferation to be restored (5 days or 3 weeks) the survival curve for stem cells of small intestine epithelium with regard to radiation dose was the same as that for non-preirradiated mice. This indicated that the proliferative potential of stem cells in these experimental conditions was not reduced.

Animals↗
PubMed1986

[Carcinogenic and promoting effects of Roussin red methyl ester (RRME) on the forestomach epithelium of mice and esophageal epithelium of rats, and its inhibition by retinamide and vitamin C].

Carcinogenic and promoting effects of RRME as isolated from the pickled vegetables in Linxian County, a high incidence area of esophageal cancer, were studied in mice and rats. RRME alone did not cause tumor in the forestomach of mice and esophagus of rats. When the mice were intubated with a single dose of nitroso-sarcosine-ethylester (NSEE), the incidence of the forestomach carcinoma was only 9.5%. However, when the mice were given gastric doses of RRME after one single dose of NSEE, the incidence was increased to 41.0%. In rats, the tumor incidence was 5.3% in nitroso-methylbenzylamine (NMBzA) group, while in NMBzA kRME group, it was 20.7%. In rats intubated with NSEE for 7 times, no carcinoma appeared in esophageal epithelium; while followed by gastric doses of RRME, the incidence of esophagus carcinoma increased up to 63.2%. The experimental results show that RRME has distinct promoting effect on the process of cocarcinogenesis initiated by NSEE and NMBzA in the forestomach of mice and esophagus of rats, but without carcinogenic effect itself. Retinamide (RI) and massive dose of vitamin C showed an obviously inhibitory effect on promoting action of RRME in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗