Epithelial Distribution Research Articles

Biomimetic Convex Implant for Corneal Regeneration Through 3D Printing.

Blindness caused by corneal damage affects millions of people worldwide, and this number continues to rise. However, rapid epithelization and a stable epithelium process are the two biggest challenges for traditional corneal materials. These processes are related to corneal curvature, which is an important factor in determination of the corneal healing process and epithelial behavior during corneal damage. In this study, smooth 3D-printed convex corneal implants based on gelatin methacrylate and collagen are generated. As epithelium distribution and adhesion vary in different regions of the natural cornea, this work separates the surfaces into four regions and studies how cells sense topological cues on curvature. It is found that rabbit corneal epithelial cells (RCECs) seeded on steeper slope gradient surfaces on convex structures result in more aligned cell organization and tighter cell-substrate adhesion, which can also be verified through finite element simulation and signaling pathway analysis. In vivo transplantation of convex implants result in a better fit with adjacent tissue and stronger cell adhesion than flat implants, thereby accelerating corneal epithelialization and promoting collagen fibers and neural regeneration within 180 days. Taken together, printed convex corneal implants that facilitate corneal regeneration may offer a translational strategy for the treatment of corneal damage.

The influence of nasal airflow on respiratory and olfactory epithelial distribution in felids.

The surface area of the maxilloturbinals and fronto-ethmoturbinals is commonly used as an osteological proxy for the respiratory and the olfactory epithelium, respectively. However, this assumption does not fully account for animals with short snouts in which these two turbinal structures significantly overlap, potentially placing fronto-ethmoturbinals in the path of respiratory airflow. In these species, it is possible that anterior fronto-ethmoturbinals are covered with non-sensory (respiratory) epithelium instead of olfactory epithelium. In this study, we analyzed the distribution of olfactory and non-sensory, respiratory epithelia on the turbinals of two domestic cats (Felis catus) and a bobcat (Lynx rufus). We also conducted a computational fluid dynamics simulation of nasal airflow in the bobcat to explore the relationship between epithelial distribution and airflow patterns. The results showed that a substantial amount of respiratory airflow passes over the anterior fronto-ethmoturbinals, and that contrary to what has been observed in caniform carnivorans, much of the anterior ethmoturbinals are covered by non-sensory epithelium. This confirms that in short-snouted felids, portions of the fronto-ethmoturbinals have been recruited for respiration, and that estimates of olfactory epithelial coverage based purely on fronto-ethmoturbinal surface area will be exaggerated. The correlation between the shape of the anterior fronto-ethmoturbinals and the direction of respiratory airflow suggests that in short-snouted species, CT data alone are useful in assessing airflow patterns and epithelium distribution on the turbinals.

Systemic Distribution of Viral Antigen in Alpacas Persistently Infected With Bovine Pestivirus

Recently, confirmed occurrences of persistent bovine viral diarrhea virus (BVDV) infection in North American alpacas have raised concerns about the role of persistently infected (PI) alpacas in transmission of virus among herds, yet only limited pathological descriptions of persistent infections in alpacas have been reported. The objective of this study was to characterize BVDV antigen distribution in 10 PI alpacas of varying age and to compare viral antigen distribution and localization in tissues of PI alpacas with 5 PI calves of varying age. Ocular dysplasia was evident in 1 PI alpaca, constituting the first reported congenital ocular lesion in PI alpacas. Viral antigen was widely distributed in alpaca tissues and was prominent in neurons, endothelial cells, and vascular tunica media myocytes but had limited distribution in lymphoid tissues and moderate distribution in epithelium of several organ systems of alpacas. Macrophages in the alpaca gastrointestinal system submucosa and lymph node medullary sinuses often had prominent labeling. In addition, only 1 alpaca had antigen labeling in the bone marrow in contrast to PI cattle. Labeled cells in calf tissues were more widely distributed, occurring prominently in lymphoid and epithelial tissues. Common features of the 2 host species were widespread antigen labeling and absence of lymphoid depletion.

Ulcerative Colitis Induces Changes on the Expression of the Endocannabinoid System in the Human Colonic Tissue

BackgroundRecent studies suggest potential roles of the endocannabinoid system in gastrointestinal inflammation. Although cannabinoid CB2 receptor expression is increased in inflammatory disorders, the presence and function of the remaining proteins of the endocannabinoid system in the colonic tissue is not well characterized.MethodologyCannabinoid CB1 and CB2 receptors, the enzymes for endocannabinoid biosynthesis DAGLα, DAGLβ and NAPE-PLD, and the endocannabinoid-degradating enzymes FAAH and MAGL were analysed in both acute untreated active ulcerative pancolitis and treated quiescent patients in comparison with healthy human colonic tissue by immunocytochemistry. Analyses were carried out according to clinical criteria, taking into account the severity at onset and treatment received.Principal FindingsWestern blot and immunocytochemistry indicated that the endocannabinoid system is present in the colonic tissue, but it shows a differential distribution in epithelium, lamina propria, smooth muscle and enteric plexi. Quantification of epithelial immunoreactivity showed an increase of CB2 receptor, DAGLα and MAGL expression, mainly in mild and moderate pancolitis patients. In contrast, NAPE-PLD expression decreased in moderate and severe pancolitis patients. During quiescent pancolitis, CB1, CB2 and DAGLα expression dropped, while NAPE-PLD expression rose, mainly in patients treated with 5-ASA or 5-ASA+corticosteroids. The number of immune cells containing MAGL and FAAH in the lamina propria increased in acute pancolitis patients, but dropped after treatment.ConclusionsEndocannabinoids signaling pathway, through CB2 receptor, may reduce colitis-associated inflammation suggesting a potential drugable target for the treatment of inflammatory bowel diseases.

Distinct and gradient distributions of connexin26 and connexin30 in the cochlear sensory epithelium of guinea pigs

Connexin26 (Cx26) and Cx30 are predominant isoforms of gap junction channels in the cochlea and play a critical role in hearing. In this study, the cellular distributions of Cx26 and Cx30 in the cochlear sensory epithelium of guinea pigs were examined by immunofluorescent staining and confocal microscopy in whole mounts of the cochlear sensory epithelium and dissociated cell preparations. The expression of Cx26 and Cx30 demonstrated a longitudinal gradient distribution in the epithelium and was reduced threefold from the cochlear apex to base. The reduction was more pronounced in the Deiters cells and pillar cells than in the Hensen cells. Cx26 was expressed in all types of supporting cells, but little Cx30 labeling was seen in the Hensen cells. Cx26 expression in the Hensen cells was concentrated mainly in the second and third rows, forming a distinct band along the sensory epithelium at its outer region. In the dissociated Deiters cells and pillar cells, Cx30 showed dense labeling at the cell bodies and processes in the reticular lamina. Cx26 labeling largely overlapped that of Cx30 in these regions. Cx26 and Cx30 were also coexpressed in the gap junctional plaques between Claudius cells. Neither Cx26 nor Cx30 labeling was seen in the hair cells and spiral ganglion neurons. These observations demonstrate that Cx26 and Cx30 have a longitudinal gradient distribution and distinct cellular expression in the auditory sensory epithelium. This further supports our previous reports that Cx26 and Cx30 can solely and concertedly perform different functions in the cochlea.

The constitutive expression of galectin-3 is downregulated in the intestinal epithelia of Crohn's disease patients, and tumour necrosis factor alpha decreases the level of galectin-3-specific mRNA in HCT-8 cells.

Galectin-3, a lectin with specificity for beta galactoside, is expressed by a variety of cells, including intestinal epithelial cells. Among other functions, galectin-3 mediates cell adhesion and is involved in inflammatory processes. In this study, we assessed the expression of galectin-3 in intestinal epithelial cells from Crohn's disease patients (n = 10), ileum adjacent to resected colon carcinoma (n = 9), unspecific bowel inflammation (n = 1), diverticulosis (n = 1), ulcerative colitis (n = 3) and healthy jejunum used for interposition in larynx carcinoma (n = 1). The role of cytokines on galectin-3 expression was a further aim of our study. The galectin-3 distribution in intestinal epithelia was analysed by immunohistochemistry, immunoblotting, immunofluorescence and reverse transcriptase polymerase chain reaction (RT-PCR). Human intestinal epithelial cell line (HCT-8) and primary cultured intestinal epithelial cells were treated with cytokines, and the effects on galectin-3 expression were determined by RT-PCR. Galectin-3 showed a homogeneous distribution in epithelia from control patients. In contrast, in epithelial cells from Crohn's disease lesions, galectin-3 staining was strongly spotted and heterogeneous. In inflamed and reorganized tissue, galectin-3 expression was markedly reduced, and was associated with disintegration of epithelia. Primary cultured epithelial cells as well as HCT-8 cells expressed galectin-3 protein and mRNA. Incubation of HCT-8 cells with tumour necrosis factor alpha (TNF-alpha), but not with other cytokines, substantially reduced galectin-3 expression as shown by semiquantitative RT-PCR. Downregulation of galectin-3 in the intestinal epithelium of Crohn's disease patients may be a consequence of enhanced TNF-alpha production by inflammatory cells, thereby contributing to the pathophysiology of the disease.

Cloning and transcriptional analysis of the promoter of the human type 2 desmocollin gene ( DSC2)

The desmocollins, together with the desmogleins, are members of the cadherin family and constitute the adhesive proteins of the desmosome type of cell-cell junction. Here we describe a study of the promoter of the human form of the DSC2 gene which is the equivalent of the first isoform expressed in the developing mouse embryo and that has the most widespread tissue distribution in epithelia and also in desmosome-bearing non-epithelial tissues. Analysis of the 5′ upstream region by DNA sequencing and Southern blotting suggested that it contained a CpG island, and a major site of transcription initiation 201 bp upstream of the translation start site was found by RNase protection and primer extension. There were no obvious CCAAT or TATA boxes present. Analysis of 1.9 kb upstream of the translation start site revealed consensus binding sites for transcription factors including Ap-2 and Sp-1, and motifs common to the promoters of other epithelially expressed genes such as keratin 14 and the desmoglein genes DSG1 and DSG3. Deletion derivatives defined a promoter of 525 bp which was active in epithelial cells and in mouse blastocysts with an intact epithelium. This promoter showed reduced expression in non-epithelial cells.

Distribution of Epithelia in the Nasal Cavity of Piglets

The epithelial distribution in the nasal cavity of piglets was studied by serial transverse sections. The epithelial distribution in the nasal cavity of healthy piglets varied according to the age of the animal. The transitional epithelium, which contained goblet cells but no ciliated cells, occupied a smaller proportion of the nasal cavity in the newborn piglets than in the 4-week-old piglets. The ciliated epithelium extended more rostrally in the newborn piglets and covered the non-mineralized rostral portion of the nasal ventral concha. At 28 days of age, the rostral cartilaginous concha is overlaid by the transitional epithelium, the respiratory epithelium covering the mineralized nasal ventral concha. The variations in the epithelial distribution according to age are discussed with regard to the greater susceptibility of newborn piglets to bacterial infection.

Nasal polyps: epithelium and goblet cell density.

The density of goblet cells was determined in 14 anterior and 15 posterior nasal polyps using the whole-mount method. The specimens were then serial cut and the type of epithelium was determined in nine localities in each polyp. The goblet cell density was correlated to the epithelial type. Pseudostratified, cylindrical epithelium was the prevailing type, occurring in 62% of anterior localities and 78% of posterior localities. Transitional types of epithelium were found in 33% of the anterior and 19% of the posterior localities. Stratified squamous epithelium occurred in 5% and 3%, respectively. The goblet cell density was highest in hyperplastic pseudostratified epithelium, whereas it was four times lower in transitional epithelium and even lower in squamous epithelium. Marked differences in the distribution of epithelium and goblet cell density were found between anterior and posterior polyps, illustrating that the epithelium constantly changes under the influence of air current, contact with other polyps, infection, growth, and age of the polyp as well as other unknown factors.

The cell surface development and actin distribution of epithelium during facial morphogenesis

The cell surface development and actin distribution of epithelium during facial morphogenesis

Protein Synthesis and Quantitative Morphology in Thyroid Tissue From Hyperthyroid Patients After Preoperative Treatment With Antithyroid orβ-Adrenergic Antagonist Drugs*

The rate of protein synthesis was measured in thyroid tissue obtained from three groups of patients undergoing thyroid surgery: group I (n = 18), hyperthyroid patients preoperatively treated with an antithyroid drug and T4; group II (n = 11), hyperthyroid patients preoperatively treated with a beta-adrenergic antagonist drug; and group III (n = 9), euthyroid patients operated on for multinodular goiter or adenoma. Quantitative morphology was studied in the resected thyroid tissue from the patients in groups I (n = 15) and II (n = 6) who had Graves' disease. While serum thyroid hormone levels became normal during preoperative treatment in group I, they remained elevated in the group II patients. The rate of protein synthesis was 2-fold higher in thyroid tissue from patients in group II than in those in groups I and III. A tendency toward an increased amount of epithelium and a reduced amount of colloid was found in thyroid tissue from patients in group II. There was a positive correlation between the rate of protein synthesis, and distribution of epithelium, and the epithelium to colloid ratio, respectively, in thyroid tissue. These results suggest that the thyroid gland of hyperthyroid patients remains hyperactive during treatment with beta-adrenergic antagonist drugs.

Immunocytochemical localization of plasmalemmal proteins in semi-thin sections of epithelial monolayers.

We describe a technique for analysis by light microscopic immunocytochemistry of the distribution of plasmalemmal proteins in polarized epithelial cells. For this purpose, Madin Darby Canine Kidney (MDCK) cells were grown to confluency on Cytodex beads, the beads were fixed with formaldehyde, and semi-thin (0.5 micron) sections were cut at liquid nitrogen temperature on an ultracryomicrotome. The distribution of the basolaterally distributed plasmalemmal protein, Na,K-ATPase, was assessed by indirect immunofluorescence using a monospecific polyclonal antibody directed against the alpha-subunit of the Na pump. Such preparations enable epithelial monolayers to be evaluated in cross-section, thus permitting unambiguous topological assessment of apical and basolateral membrane proteins. Thus, the spatial uncertainties encountered in en face examination of membrane protein distribution in epithelia grown on solid supports are largely obviated. In addition, we describe a technique for removal of the bead matrix, which markedly reduces nonspecific background staining and improves access of reagents to the basal cell surface, thus permitting localization of basal lamina components.

Introduction: trends in epithelial transport and control.

ABSTRACT Osmotic and ionic regulation ultimately depend on epithelial transport mechanisms and their control in most metazoans, although intracellular osmotic adjustments are probably more important in marine osmoconformers. There are a great variety of osmoregulatory organs throughout the animal kingdom and physiological information about many of these is still so incomplete that it seemed inappropriate to attempt a comprehensive review or synthesis of osmoregulation in a small discussion meeting of this type. However, given the general conservative nature of many cellular processes during the course of animal evolution, we might anticipate common protein carrier mechanisms which are organized and controlled in a limited number of ways within most epithelia. A number of such general concepts and models of epithelial transport have developed over the last ten years and these should prove useful in the future when less well studied osmoregulatory organs are investigated. With this in mind, we have included in this volume reports on some of the most intensively studied epithelia having a range of different regulatory functions. These papers will indicate (1) the types of primary and secondary transport mechanisms which are now well established and partially characterized, (2) their typical asymmetrical distribution in epithelia, and (3) cellular processes associated with their regulation. (4) Finally we consider the relative importance and characteristics of the paracellular route for ion and fluid transfer across epithelia.

Proteoglycans in human gingiva: Molecular size distribution in epithelium and in connective tissue

The major extracellular, non-fibrous macromolecules in human gingiva are proteoglycans. These sulphated, uronic acid-containing macromolecules are synthesized in vitro by both gingival epithelium and its underlying connective tissue. Biochemical analyses were carried out on cultured human predominantly gingival epithelium and predominantly connective tissue in media containing appropriate radioactive precursor molecules. The proteoglycans were extracted with salt solutions of varying concentration and characterized by means of column chromatography and liquid scintillation counting. The major differences noted between the macromolecules extracted from these two closely apposed regions were molecular size, and the ability or not to form large self-aggregatable macromolecules. In general, the epithelial proteoglycans are larger than connective tissue proteoglycans. Proteoglycans from gingival epithelium are able to self-aggregate to form large macromolecules with mol. wt in excess of 2 × 10 6 which are essential for the maintenance of tissue integrity.

Distribution of epithelia and glands of the nasal septum mucosa in the rat.

A histotopographic study of the nasal septum mucosa in rats was made using semi-serial sections stained with PAS-hematoxylin, reconstructed in form of maps representing the structure in a sagittal plane. The stratified squamous, respiratory and olfactory epithelia and Masera's organ cover 14.8, 43.6, 41.6 and 1.8%, respectively, of the septal surface (117.1 mm2). In the vestibular region, only ducts of PAS-negative glands of the respiratory region are found, and below the septum there is the infraseptal gland with PAS-negative acini. In the respiratory region, PAS-negative acinous glands form two groups: the superior and the inferior one occupying 10.5 and 1.5%, respectively, of the septal area. PAS-positive acinous glands are in the inferior half of the respiratory region and in a small anteroinferior portion of the olfactory region. Besides goblet cells broadly distributed, the respiratory epithelium presents scattered intraepithelial PAS-positive glands which are concentrated in the anterior portion and close to the nasopharyngeal duct. In the olfactory region prevail Bowman's PAS-positive glands which are also present in the mucosa of Masera's organ, but are not seen in the olfactory mucosa of Jacobson's organ. In the latter, PAS-positive glands are found in the respiratory mucosa. Globular leukocytes, cells of connective tissue origin, are constantly infiltrating the superior regions of the respiratory and olfactory epithelia, being more numerous in female rats.

THE ROLE OF THE ENDOTHELIUM IN INFLAMMATION.

It would certainly be superfluous before a body of representative pathologists to give a review of those publications which from time to time for the last forty years have considered the exact position the endothelial cells should occupy as regards their origin and classification. Indeed, the discussion began somewhat earlier, for Henle in a paper on the distribution of epithelium in the human body, written in 1838, noted certain facts which seemed to him to presage a change of ideas regarding the cells that line serous cavities. Not only has the discussion continued until the present time, but it is by no means ended; its very existence furnishes a good illustration of the unity of the sciences pertaining to medicine, for investigators in single branches are unable to harmonize the results of their own researches with those made in other departments; it is also often apparent that there is not