Epithelial membrane mucins

Until recently the only human epithelial membrane mucin was the MUCl mucin although a rat sialomucin (sialomucin complex, SMC) with a similar structure has also identified and characterized [13]. With the determination of the full length sequence of the MUC4 apomudn, it has become apparent that the rat sialomucin is... 

Briefly, upon release of the macromolecular drug from the delivery system, the drug should withstand hydrolysis and enzymatic activity in the extracellular milieu at the site of absorption. In the case of nonparenteral delivery, the unstirred water layer and especially the viscous mucin layer in particular, both present at the surface of epithelia constitute a barrier for absorption of biotechnology-based pharmaceuticals and must be permeated for the biomacromolecule to reach the surface of the epithelial membrane. A... 

Immunohistochemistry can play an important role in the diagnosis and classification of mucinous tumors of the ovary. Two types of primary mucinous tumors occur in the ovary. Tumors composed of cells with an intestinal phenotype are most common, but a minority of mucinous tumors has an endocervical-like or seromucinous phenotype. These two types of mucinous tumors have different immunophenotypes, and immunostains can be used to differentiate between the two types. Immunostains for cytokeratin or epithelial membrane antigen can help identify foci of microinvasion. 

An ideal bioadhesive should be nontoxic, nonabsorbable, and nonirritating to the mucus membrane, form a strong noncovalent bond with the mucin-epithelial cell surfaces, allow easy incorporation of drug and should not offer hindrance to drug release, and should not decompose on storage or during the shelf-life of the dosage form. Some of the other desirable characteristics of the polymer have been discussed under bioadhesion. 

Schroten, H., Hanisch, F. G., Plogmann, R., Hacker, J., Uhlenbruck, G., Nobis-Bosch, R., and Wahn, V. (1992). Inhibition of adhesion of S-fimbriated Escherichia coli to buccal epithelial cells by human milk fat globule membrane components A novel aspect of the protective function of mucins in the nonimmunoglobulin fraction. Infect. Immun. 60,2893-2899. 

Histochemical demonstration of most of the O-acetylated sialic acids is possible because substituents on the side chain of Neu hinder periodate oxidation of this part of the molecule to an extent dependent on the number and position of the O-acetyl groups already mentioned. Correspondingly, removal of these ester groups by alkaline treatment (0.5% KOH in 70% ethanol91) may increase the staining reaction of a sialic acid. For example, the presence of O-acylated sialic acids has been demonstrated in colonic, epithelial mucin of man and various mammals (summarized in Ref. 91), in healthy and diseased, human small-intestine,188-190 in bovine submandibular gland,182 in mouse and rat erythrocyte-membranes,191 and in human lymphocytes.192... 

The construction of the eye is completely different. The outer layer of this mucosa consists of a tiny tear layer of lipids and water which covers a superficial epithelium closed by double layer lipid membranes of 30-70 nm size interconnected by tight jnnctions. Three to seven layers of epithelial cells cover the stromal structures of conjunctiva or cornea. The conjnnctival surface has interposed cells secreting small amonnts of mucin, the so-called goblet cells, which are typically missing within the corneal epithelinm. The regeneration of epithelial structnres is dne to the limbal stem cells located deep in the Vogt s crypts, for the cornea. 

J. Y. and Plaisancie P. (2007) Leptin modulates the expression of secreted and membrane-associated mucins in colonic epithelial cells by targeting PKC, PI K, and MAP.K. Am J Physiol Gastrointest Liver Physiol 293,G365-G373... 

CRITICAL ASSESSMENT OF THE METHOD Porcine cornea are similar to human cornea in that both have 5-7 layers of epithelial cells and a Bowman s membrane. Bovine cornea differs in that it has 10 layers of epithelial cells and no Bowman s membrane. Porcine and Bovine comeal cultures both differ in certain aspects from in vivo animal cornea. The latter has the presence of an overlying mucin layer... 

Encoded by the MUCI gene on chromosome I and a derivative human antigen, EMA is a transmembrane glycoprotein of the breast mucin complex, and its expression is increased in carcinomas.Unlike normal breast, in which EMA is present on the apical cell membrane, neoplasms demonstrate EMA on the entire circumference of the cell membrane. Increased amounts of the large glycoprotein interfere with cell-to-cell and cell-to-matrix adhesion in neoplastic cells. The utility of EMA antibody is in the detection of epithelial differentiation, as a supplement to the cytokera-tins. Spindle cell, small cell, and large cell neoplasms may on rare occasion be stained with EMA but may be only focally positive for cytokeratins. 437... 

HBME-1 and show cell membrane staining for EM A and HMEG-2. Ultrastructurally, mucin-positive epithelial mesotheliomas frequently contain crystalloid material (Eig. 12.60) in intracellular neolumens, in glandular spaces formed by neoplastic cells, or in the extracellular space. In our experience, this crystalloid material is unique to epithelial mesotheliomas. 

FIGURE 18.24 Many non-mucinous ovarian epithelial tumors, particularly serous tumors, exhibit positive staining for CA125. This microscopic serous carcinoma, found in a woman with a family history of ovarian cancer, illustrates the typical strong membranous staining pattern. 

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