Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Colorectal primary carcinomas and metastases from 20 Dukes' stage C or D patients were examined for the immunohistochemical localization and contents of various fucosylated N-acetyl-lactosamine oligomers by specific monoclonal antibodies (MAbs). MAbs used were SH1, specific for Lewis X antigen; FH4, specific for dimeric Lewis X antigen; FH6, specific for sialyl-dimeric Lewis X antigen; and KH1, specific for Lewis Y-Lewis X antigen. The distribution of the carbohydrate antigens identified by these MAbs was heterogeneous within the primary tumor as well as within the metastatic lesion. Examinations of serial sections indicated that areas within an individual tumor which were stained with one MAb were not always reactive with the other MAbs, although these four MAbs identify closely related structures. The degree of MAb reactivity with carcinoma sections was classified by percentage positive carcinoma cells, and primary tumors and metastases from the same patients were compared. An equivalent or higher proportion of carcinoma cells in the metastatic lesions were reactive with MAb FH6 than in the primary colon carcinomas, but each correlation was not seen with the other MAbs. Electrophoretic separation of tumor tissue extracts followed by staining with these MAbs revealed that a component having an approximate molecular weight of 1,000,000 is the major site for the binding of MAbs, FH6, FH4, and KH1. The electrophoretic mobility of the antigenic molecule on polyacrylamide gels as shown by direct MAb bindings was slightly different from that of a major sialomucin revealed by wheat germ agglutinin in the same tissues. MAb FH6 binding to a high molecular weight component was eliminated by prior treatment of the glycoprotein with mild acid or sialidase to remove sialic acid. Simultaneously, binding of MAb SH2, specific for dimeric Lex antigen, to this component increased. An extract was prepared from a liver metastasis, and high molecular weight components were isolated by gel filtration and then fractionated by DEAE-cellulose ion exchange chromatography. A fraction eluted from DEAE-cellulose between 0.10-0.25 M sodium chloride contained most of the MAb FH6 reactivity, as shown by antibody affinity chromatography. These results support a hypothesis that high molecular weight glycoproteins produced by colorectal carcinoma tissues are heterogeneous with regard to their carbohydrate chains and their antigenic structures may change during tumor progression.
 ...
PMID:Sialyl-dimeric Lewis-X antigen expressed on mucin-like glycoproteins in colorectal cancer metastases. 197 61

Activated platelets are known to express P-selectin, a lectin-like adhesion receptor (CD62), through which they bind to sialyl Lewis X (sLex) ligands displayed on the membranes of leukocytes. To determine whether direct platelet-platelet interactions via P-selectin/sLex interactions are also possible, we have examined the ganglioside extract of human blood platelets for the presence of sLex ligands. Using the sensitive method of high-performance thin-layer chromatography (HPTLC)-immunostaining with the monoclonal antibody (mAb) CSLEX or with sialidase followed by mAbs MC480 or PM81, eight sLex bands were demonstrated at Rf 0.01, 0.03, 0.05, 0.06, 0.08, 0.10, 0.14 and 0.21 in the solvent 45:55:10 chloroform-methanol-aqueous 0.02% CaCl2. The sensitivity of all eight bands to sialidase or endoglycoceramidase confirmed that they were gangliosides. Comparison of the HPTLC mobilities and densities of platelet bands with those from five other human tissues (granulocytes, monoblasts, kidney, aortic endothelium and erythrocytes) in three different solvents revealed three major bands associated with platelets: 3 (Rf0.03), 6 (0.08) and 14 (0.21). Platelet bands were demonstrated not to have resulted from granulocyte contamination. Partial purification of platelet sLex gangliosides by high-performance liquid chromatography and their reaction with 14 oligosaccharide-specific mAbs (FH4, FH5, LM112-161, LM119-181, A5, 1B2, BR55-2, BE2, ES4, MC631, MH04, SH34, P001 and MC813-70) revealed that band 6 is a multifucosylated neolacto ganglioside and band 14 is a branched, disialo neolacto fucoganglioside. Platelet band 3 combined the features of both bands 6 and 14, and reacted differently than granulocyte band 3. These partial structures resemble gangliosides associated with adhesion in other cell systems. It is concluded that platelets express tissue-specific sLex gangliosides (sLex ligands). Thus, it is possible that platelet-platelet binding may be mediated at least partially through P-selectin/sLex interactions, especially after platelet activation.
 ...
PMID:Detection in human blood platelets of sialyl Lewis X gangliosides, potential ligands for CD62 and other selectins. 856 44