scholarly journals Prostaglandins and Mucosal Defensive Mechanisms

1990 ◽  
Vol 4 (3) ◽  
pp. 95-107 ◽  
Author(s):  
Gerald P Morris ◽  
Todd E Williamson ◽  
Taimi T Hynna
Keyword(s):  
Normal Mucosa ◽  
Mucosal Immune Response ◽  
Unstirred Layer ◽  
Ph Gradient ◽  
Apical Surface ◽  
Adaptive Cytoprotection ◽  
Epithelial Migration ◽  
Defensive Responses ◽  
Mucosal Cells ◽  
Unstirred Layer Ph

The first line of mucosa! defence includes the juxtamucosal unstirred layer/pH gradient and the apical surface of the luminal epithelial cells. Many damaging agents, including nonsteroidal anti-inflammatory drugs (NSAIDs), can overwhelm these defences and destroy extensive regions of the luminal epithelium. This damage is readily tolerated in the normal mucosa. Furthermore, a combination of increased mucosal bloodflow, epithelial migration, mucus release, and efflux of bicarbonate- rich fluid usually allows rapid recovery of mucosa I integrity. In the presence of vascular damage and congestion, however, luminal acid can kill mucosal cells and destroy the substrate necessary for repair (by epithelial migration). Damage of this type results in the production of hemorrhagic erosions, which may then develop into chronic ulceroinflammatory disease if healing is prevented by excess luminal acid or by impaired mucosal immune response. Endogenous and exogenous prostaglandins could affect all aspects of the mucosal defensive responses, from the juxtamucosal unstirred layer/pH gradient (via effects on secretion of bicarbonate, acid and mucus, as well as stimulation of fluid efflux) to the function of the mucosal immune system. Protection against the acute damage produced by topically administered NSAIDs or concentrated ethanol can result from either administration of prostaglandins or topical application of'mild irritants'. This is referred to as 'adaptive cytoprotection'. Parenterally administered NSAIDs can also produce mucosa! erosions. Protection against this type of damage may depend on the effects of prostaglandins on neural and contractile elements in the mucosa. Studies on animal models also suggest that by preventing acute hemorrhagic erosions, prostaglandins may prevent the development of chronic ulcer in susceptible individuals.

scholarly journals Differential Expression of Ribosomal Proteins in Human Normal and Neoplastic Colorectum

2003 ◽  
Vol 51 (5) ◽  
pp. 567-573 ◽  
Author(s):  
Hide Kasai ◽  
Daita Nadano ◽  
Eiko Hidaka ◽  
Kayoko Higuchi ◽  
Masatomo Kawakubo ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Ribosomal Proteins ◽  
Protein Biosynthesis ◽  
Secretory Granules ◽  
Expression Patterns ◽  
Normal Mucosa ◽  
Cellular Processes ◽  
Colorectal Mucosa ◽  
Colorectal Cancer Cells ◽  
Mucosal Cells

Ribosomal proteins are a major component of ribosomes and play critical roles in protein biosynthesis. Recently it has been shown that the ribosomal proteins also function during various cellular processes that are independent of protein biosynthesis therefore called extraribosomal functions. In this study we have, for the first time, determined the expression profile of 12 ribosomal proteins (Sa, S8, S11, S12, S18, S24, L7, L13a, L18, L28, L32, and L35a) in normal epithelia of human colorectal mucosa using immunohistochemistry (IHC) and then compared their expression patterns with those of colorectal cancer. In the normal mucosa, ribosomal proteins were largely associated with the ribosomes of mucosal epithelia, and the expression level of ribosomal proteins, except for S11 and L7 proteins, was markedly increased in associated with maturation of the mucosal cells. On the other hand, these ribosomal proteins were markedly decreased in colorectal cancer compared with the normal mucosa. By contrast, S11 and L7 ribosomal proteins were rarely associated with the ribosomes of colorectal epithlia except immature mucosal cells, whereas their expression levels were significantly enchanced in colorectal cancer cells. In addition, L7 ribosomal protien was detected in the secretory granules of the enterochromaffin cells in the colorectal mucosa and in carcinoma cells expressing chromogranin A. These results indicate that the expression of ribosomal proteins is differentially regulated not only in normal mucosa but also in carcinoma of human colorectum, and suggest an extraribosomal function of L7 ribosomal protein in neuroendocrine function.

scholarly journals Reversible Alkalinization by Manduca Sexta Midgut

1990 ◽  
Vol 150 (1) ◽  
pp. 247-256 ◽  
Author(s):  
JULIAN A.T. DOW ◽  
MICHAEL J. O'DONNELL
Keyword(s):  
Manduca Sexta ◽  
Time Course ◽  
Ph Gradient ◽  
Apical Surface ◽  
Ph Gradients ◽  
Electrical Potentials ◽  
Posterior Midgut ◽  
Inverted Microscope ◽  
Anterior Midgut ◽  
K Transport

1. Midguts of the larva of the tobacco hornworm larva, Manduca sexta, were isolated, pinned out and double perfused on the stage of an inverted microscope. The pH gradients across the anterior, middle and posterior regions of the gut were measured with a double-barrelled pH microelectrode, simultaneously with electrical potentials and the transepithelial potential difference (TEP). 2. The microenvironment surrounding the apical surface is more alkaline, and that surrounding the basal surface more acid, than either the perfusion medium or the intracellular pH. Under double perfusion, a stable gradient of 1.4 pH units is observed across the middle midgut. A similar gradient is found across the anterior midgut, but no significant pH difference occurs across the posterior midgut. 3. The pH gradient across the middle midgut is reversibly and symmetrically collapsed by anoxia, implying that it is sustained by a process requiring oxidative phosphorylation. 4. The time course of decay and reconstitution of the pH gradient matches closely the activity of electrogenic K+ pumping, as measured by the TEP. 5. These results are consistent with a model for high pH generation which links electrogenic K+ transport into the goblet cavities with net alkalinization of the lumen of the anterior and middle midgut regions.

TheDrosophila ribbongene encodes a nuclear BTB domain protein that promotes epithelial migration and morphogenesis

Development ◽  
2001 ◽  
Vol 128 (23) ◽  
pp. 4923-4933 ◽  
Author(s):  
Katherine Shim ◽  
Kimberly J. Blake ◽  
Joseph Jack ◽  
Mark A. Krasnow
Keyword(s):  
Apical Cell ◽  
Basal Membrane ◽  
Binding Motif ◽  
Apical Surface ◽  
Basal Surface ◽  
Tracheal System ◽  
Epithelial Migration ◽  
Tracheal Cell ◽  
Branch Formation ◽  
Membrane Protrusions

During development of the Drosophila tracheal (respiratory) system, the cell bodies and apical and basal surfaces of the tracheal epithelium normally move in concert as new branches bud and grow out to form tubes. We show that mutations in the Drosophila ribbon (rib) gene disrupt this coupling: the basal surface continues to extend towards its normal targets, but movement and morphogenesis of the tracheal cell bodies and apical surface is severely impaired, resulting in long basal membrane protrusions but little net movement or branch formation. rib mutant tracheal cells are still responsive to the Branchless fibroblast growth factor (FGF) that guides branch outgrowth, and they express apical membrane markers normally. This suggests that the defect lies either in transmission of the FGF signal from the basal surface to the rest of the cell or in the apical cell migration and tubulogenesis machinery. rib encodes a nuclear protein with a BTB/POZ domain and Pipsqueak DNA-binding motif. It is expressed in the developing tracheal system and other morphogenetically active epithelia, many of which are also affected in rib mutants. We propose that Rib is a key regulator of epithelial morphogenesis that promotes migration and morphogenesis of the tracheal cell bodies and apical surface and other morphogenetic movements.

Localization of transmembrane mucin MUC1 on the apical surface of oral mucosal cells

2019 ◽  
Vol 43 (4-5) ◽  
pp. 184-189 ◽  
Author(s):  
Ellinoora Sirviö ◽  
Jopi J. W. Mikkonen ◽  
Arto P. Koistinen ◽  
Ilkka Miinalainen ◽  
Arja M. Kullaa
Keyword(s):  
Apical Surface ◽  
Mucosal Cells

Bacterial-Mucosal Cell Junctional Complexes

1974 ◽  
Vol 32 ◽  
pp. 144-145
Author(s):  
Roger C. Wagner
Keyword(s):  
Intestinal Wall ◽  
Rat Colon ◽  
Mucosal Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Mucosal Cells ◽  
Mucosal Lining ◽  
Degenerative Alterations ◽  
Junctional Complexes ◽  
Intestinal Mucosal Cells

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.

Fine Structural Localization of Acyltransferases Involved in Lipid Synthesis in Intestinal Mucosa.

1970 ◽  
Vol 28 ◽  
pp. 54-55
Author(s):  
R. J. Barrnett ◽  
J. A. Higgins
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Lipid Synthesis ◽  
Mucosal Cell ◽  
Structural Localization ◽  
Morphological Studies ◽  
Mucosal Cells ◽  
Initial Appearance ◽  
Sh Group ◽  
Hydrolysis Of ◽  
Intestinal Mucosal Cells

The main products of intestinal hydrolysis of dietary triglycerides are free fatty acids and monoglycerides. These form micelles from which the lipids are absorbed across the mucosal cell brush border. Biochemical studies have indicated that intestinal mucosal cells possess a triglyceride synthesising system, which uses monoglyceride directly as an acylacceptor as well as the system found in other tissues in which alphaglycerophosphate is the acylacceptor. The former pathway is used preferentially for the resynthesis of triglyceride from absorbed lipid, while the latter is used mainly for phospholipid synthesis. Both lipids are incorporated into chylomicrons. Morphological studies have shown that during fat absorption there is an initial appearance of fat droplets within the cisternae of the smooth endoplasmic reticulum and that these subsequently accumulate in the golgi elements from which they are released at the lateral borders of the cell as chylomicrons.We have recently developed several methods for the fine structural localization of acyltransferases dependent on the precipitation, in an electron dense form, of CoA released during the transfer of the acyl group to an acceptor, and have now applied these methods to a study of the fine structural localization of the enzymes involved in chylomicron lipid biosynthesis. These methods are based on the reduction of ferricyanide ions by the free SH group of CoA.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Organization of tight junctions in the choroid plexus epithelium

1978 ◽  
Vol 36 (2) ◽  
pp. 336-337
Author(s):  
B. Van Deurs ◽  
J. K. Koehler
Keyword(s):  
Choroid Plexus ◽  
Present Report ◽  
Freeze Fracture ◽  
Barrier Properties ◽  
Cell Junctions ◽  
Structural Basis ◽  
Apical Surface ◽  
Choroid Plexus Epithelium ◽  
Solid Nitrogen ◽  
Special Composition

The choroid plexus epithelium constitutes a blood-cerebrospinal fluid (CSF) barrier, and is involved in regulation of the special composition of the CSF. The epithelium is provided with an ouabain-sensitive Na/K-pump located at the apical surface, actively pumping ions into the CSF. The choroid plexus epithelium has been described as “leaky” with a low transepithelial resistance, and a passive transepithelial flux following a paracellular route (intercellular spaces and cell junctions) also takes place. The present report describes the structural basis for these “barrier” properties of the choroid plexus epithelium as revealed by freeze fracture.Choroid plexus from the lateral, third and fourth ventricles of rats were used. The tissue was fixed in glutaraldehyde and stored in 30% glycerol. Freezing was performed either in liquid nitrogen-cooled Freon 22, or directly in a mixture of liquid and solid nitrogen prepared in a special vacuum chamber. The latter method was always used, and considered necessary, when preparations of complementary (double) replicas were made.

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