Sialomucins

Baumheter S, Singer MS, Henzel W, Hemmerich S, Renz M, Rosen SD, Lasky LA (1993) Binding of L-selectin to the vascular sialomucin CD34. Science 262(5132) 436-438... 

These are high-molecular-weight (>100 kDa) sialomucins, consisting of a core protein with a tandem repeat of 20 amino acids and heavy glycosylations... 

Pflugfelder, S.C., et al. 2000. Detection of sialomucin complex (MUC4) in human ocular surface epithelium and tear fluid. Invest Ophthalmol Vis Sci 41 1316. 

Histochemical techniques for detecting substrate before and after enzyme treatment are extremely useful in studies on cellular structure. One of the oldest histochemical tests utilized saliva to identify suspected glycogen or starch. More definitive results are obtained when thin sections of a tissue are incubated in a buffered solution of purified amylase and stained for poly-utc-glycols. Material stained by periodic acid-Schiff reagent in the control, but not in the section exposed to amylase, is assumed to be glycogen or starch. Two more of the numerous histochemical techniques associated with localization of substrate are—using hya-luronidase to locate hyaluronic acid and chondroitin 4- and 6-sulfates (179) and using neuraminidases to locate sialomucins (180). By use of electron microscopy in combination with the histochemical technique subcellular localization can be obtained. 

Sialomucins (Odin) protein, sialic acid, N-acetylgalactosamine... 

Meyer (M34, M35) classified the neutral polysaccharide of hog gastric mucin as mucoid, since it contained over 4% hexosamine. This probably corresponded to the mixture of the carbohydrate moieties of fuco-mucin and sialomucin, whereas his acidic mucopolysaccharide (mucoitin sulfuric acid) consisted perhaps of a mixture of acidic aminopolysac-charides (mucopolyuronides) and possibly some sialic acid. 

Sialomucins [Odin (02)] or sialoproteins [Werner (W9)] are another type of mucosubstance found in the stomach. Their carbohydrate moiety is composed of equimolecular amounts of acetylhexosamine (usually galactosamine) and sialic acid. The latter is a group name for several materials derived from the same basic substance, neuraminic acid. In human mucosubstances, the N-acetylneuraminic acid is the main form of sialic acid (FI, F2). In hog stomach, the sialic acid consists of 80%... 

Relationship of sialomucins to cancer of the stomach is demonstrated by the following (1) high concentration of sialic acid in the cancer... 

Subtle changes in pH, particularly within the acid range, may break some of the bonds of the carbohydrate moiety and liberate sialic acid. Submaxillary sialomucin loses its sialic acid at pH 3 and 37°C, and fucose and galactose are also slowly liberated from gastric fucomucins at pH 1.1-1.8 at 37°, according to Waldron Edward (W5). 

The composition of various blood group substances from human gastric juice, as reported by Masamune et al. (M22), Tiba (T29) and Yosizawa (Y3), varies only little. The N content is in the range 4.7-4.9%, hexos-amine 29.0-30.8%, galactose 26.6-27.8%, fucose 12.9-14.1%, and sialic acid 3.0-5.2%. Presence of considerable amounts of sialic acid in these materials perhaps indicates their contamination with sialomucin. 

We found that gastrone activity in human gastric juice is associated with at least two materials (1) carbohydrate of sialomucin, and (2) protein, exhibiting the mobility of y-globulin. It is affected by acid-pepsin digestion, but is retained in some split products of inhibitory materials (K31). The significance of these findings is discussed in Section 8.3. 

Hilkens J, Buijs F, Ligtenberg M. Complexity of MAM-6, an epithelial sialomucin associated with carcinomas. Cancer Res. 1989 49 786-793. 

EHBT carcinomas are similar, both morphologically and immunophenotypically, to other foregut carcinomas, namely pancreatic and gastro-esophageal cancers. Their similarity to pancreatic ductal carcinoma is such that they are often classified together as pancreatobiliary-type adenocarcinoma. Mucin, in particular sialomucin, nonsulfated, or neutral types, is demonstrable by histochemical or immunohistochemical stains in almost all cases and may be abundant. ... 

Hydrating Sodium chloride Activate sialomucin synthesis Correct water and... 

Fig. 2. Histochemical staining of control and VeMi-null aorta for elastin, mucins, and smooth muscle. (A) Control aorta stained for elastin with Hart s stain showing 5-6 elastic lamellae and (B) Ae 7-null aorta showing the abnormal separation between the elastic lamellae. (C) Control aorta stained for sialomucins with Alcian blue (blue) with elastic lamellae appearing opaque and (D) Neul-miR aorta stained for sialomucins indicating the large mass of positive material between elastic lamellae. (E) Control aorta immunostained for smooth muscle with an antibody to alpha-smooth muscle actin (red) showing the thin area between elastic lamellae and (F) Afe 7-nuU aorta showing the increased mass of smooth muscle between elastic lamellae, whereas some areas were devoid of smooth muscle (arrow). Scale bar, 22 pm. From Starcher et (See Color Plate 46.)...

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