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)

The pathogenicity of enterobacteria often correlates with their production of neuraminidase (sialidase). Forty-nine Helicobacter pylori isolates have therefore been examined for their production of neuraminidase and other glycosidases. All 49 isolates produced considerable neuraminidase (median 228 IU/microg protein, interquartile range 121-370), pH optimum 7.5. Nine of the 49 also produced fucosidase (median 23 IU/microg protein, interquartile range 12-39), pH optimum 7.0. Production of these enzymes did not correlate with bacterial Cag A expression or duodenal ulceration. Neutrophils exposed to neuraminidase show increased adherence to endothelium so the neuraminidase production by H. pylori could partly explain the predominant neutrophil inflammatory infiltrate seen in H. pylori-associated gastritis. Inhibition of this enzyme by use of neuraminidase-inhibitors could be a useful therapeutic approach.
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PMID:The production of neuraminidase and fucosidase by Helicobacter pylori: their possible relationship to pathogenicity. 874 5

CAM 17.1 is an antimucin monoclonal antibody which has recently been proven valuable as a reagent for serological diagnosis of pancreatic cancer. A series of studies have been performed to characterise its epitope. First it was screened immunohistochemically against a wide range of formalin-fixed normal and neoplastic human tissues and showed widespread binding to mucin throughout the gastro-intestinal tract, in both normal and malignant tissues. In pancreas, strong intracellular staining of acinar and ductal cells was found in normal tissue and in carcinoma cells in tumours. Normal stomach showed only weak staining (n = 6), but gastritis with metaplasia showed strong staining (n = 4). Staining of colonic mucosa from patients of known Lewis phenotype showed Le(a+b-) (7/8) and Le(a-b+) (4/6) samples to be positive, but not Le(a-b-) (0/3) samples. CAM 17. 1 agglutinated all donor erythrocytes tested at 4 degreesC regardless of blood group, whereas cord blood red cells were not agglutinated. Since I antigen is the only antigen known to be present on all adult red blood cells but absent from cord blood, this suggests probable involvement of this antigen in the binding site. The agglutination was abolished by sialidase treatment of the red cells and immunoblotting with slot-blotted mucin showed that binding was both acid and sialidase sensitive indicating the involvement of sialic acid in the binding site. These studies show that CAM 17.1 binds to a sialic-acid-containing determinant of mucin, probably sialyl-I, which epitope shows wide distribution throughout the gastro-intestinal tract.
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PMID:Pancreatic tumour marker anti-mucin antibody CAM 17.1 reacts with a sialyl blood group antigen, probably I, which is expressed throughout the human gastrointestinal tract. 981 91

Adherence of Helicobacter pylori to inflamed gastric mucosa is dependent on the sialic acid-binding adhesin (SabA) and cognate sialylated/fucosylated glycans on the host cell surface. By in situ hybridization, H. pylori bacteria were observed in close association with erythrocytes in capillaries and post-capillary venules of the lamina propria of gastric mucosa in both infected humans and Rhesus monkeys. In vivo adherence of H. pylori to erythrocytes may require molecular mechanisms similar to the sialic acid-dependent in vitro agglutination of erythrocytes (i.e., sialic acid-dependent hemagglutination). In this context, the SabA adhesin was identified as the sialic acid-dependent hemagglutinin based on sialidase-sensitive hemagglutination, binding assays with sialylated glycoconjugates, and analysis of a series of isogenic sabA deletion mutants. The topographic presentation of binding sites for SabA on the erythrocyte membrane was mapped to gangliosides with extended core chains. However, receptor mapping revealed that the NeuAcalpha2-3Gal-disaccharide constitutes the minimal sialylated binding epitope required for SabA binding. Furthermore, clinical isolates demonstrated polymorphism in sialyl binding and complementation analysis of sabA mutants demonstrated that polymorphism in sialyl binding is an inherent property of the SabA protein itself. Gastric inflammation is associated with periodic changes in the composition of mucosal sialylation patterns. We suggest that dynamic adaptation in sialyl-binding properties during persistent infection specializes H. pylori both for individual variation in mucosal glycosylation and tropism for local areas of inflamed and/or dysplastic tissue.
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PMID:SabA is the H. pylori hemagglutinin and is polymorphic in binding to sialylated glycans. 1712 61