Enhanced ability of heparin-carrying polystyrene (HCPS) to bind to heparin-binding growth factors and to inhibit growth factor-induced endothelial cell growth.
(41/567)
Heparin-carrying polystyrene (HCPS) consists of low-molecular-weight heparin chains enriched in trisulfated disaccharide structures linked to a polystyrene core. In this study, the interactions between HCPSs of various molecular weights and heparin-binding growth factors, VEGF(165), FGF-2, and HGF, were compared to the interactions of the same factors with native heparin, periodate-oxidized heparin (IO(4)-heparin) and periodate-oxidized alkaline-degraded heparin (IO(4)-LMW-heparin). The binding of each growth factor to heparin-agarose beads (heparin-beads) was more strongly inhibited by HCPSs in a molecular weight-dependent manner than by native heparin or the modified heparins, indicating a stronger interaction between HCPS and these growth factors. HCPSs also inhibit heparin-binding growth factor-induced endothelial cell growth in a molecular weight-dependent manner much more strongly than the native or modified heparins. However, HCPSs did not inhibit the mitogenic activity of VEGF(121), which has a non-heparin-binding nature. Thus, HCPSs exhibit enhanced abilities to interact with each of the heparin-binding growth factors studied and to inhibit heparin-binding growth factor-induced endothelial cell proliferation in a molecular weight-dependent manner. These effects might be ascribed to the heparin-clustering effect of HCPSs. (+info)
Identification of a methyltransferase from Mycobacterium smegmatis involved in glycopeptidolipid synthesis.
(42/567)
Glycopeptidolipids (GPLs) are major components of the cell walls of several species of mycobacteria. We have isolated a transposon mutant of Mycobacterium smegmatis that is unable to synthesize mature GPLs and that displays a rough colony morphology. The disrupted gene, mtf1, shares a high degree of homology with several S-adenosylmethionine-dependent methyltransferases. The enzyme encoded by mtf1 is required for the methylation of a single rhamnose residue that forms part of the conserved GPL core structure. This conclusion is supported by the finding that (a) the mutant synthesized only GPLs with undermethylated (either mono- or nonmethylated instead of di- or trimethylated) rhamnose residues; (b) complementation of the mutant with a wild-type copy of mtf1 restored high levels of synthesis of GPLs containing di- and trimethylated rhamnose; and (c) S-adenosylmethionine-dependent methylation of rhamnosylated GPLs could be detected in cell lysates of wild-type cells and mtf1-complemented mutant cells, but not in mutant cells lacking intact mtf1. Structural analysis of wild-type and mutant GPLs suggests that disruption of mtf1 specifically inhibits addition of O-methyl groups to the 3 (or 2)-position of the rhamnose. In the absence of 3-O-methylation, further methylation of GPL rhamnose is apparently inhibited, and overall GPL synthesis is down-regulated by 90%. (+info)
Teasterone-3-O-beta-D-glucopyranoside, a new conjugated brassinosteroid metabolite from lily cell suspension cultures and its identification in lily anthers.
(43/567)
The new brassinosteroid conjugate, teasterone-3-O-betaD-glucopyranoside, was found as a metabolite of teasterone in lily cell suspension cultures. Its structure was determined by means of FAB-MS and 1H-NMR upon comparison with the authentic compound. Furthermore, its presence in lily anthers was confirmed by FAB-MS and LC-APCI-SIM data. This is the first natural brassinosteroid conjugate glucosylated at a hydroxyl group in ring A. (+info)
Studies on the specificity and sensitivity of the influenza C virus binding assay for 9-O-acetylated sialic acids and its application to human melanomas.
(44/567)
The sensitivity and specificity of two influenza C virus assays, solid-phase and overlay assays, were investigated using naturally occurring 9-O-acetylated GD(3), rat serum glycoproteins containing 60% of N-acetyl-9-O-acetylneuraminic acid, and synthetically O-acetylated sialylated compounds. The sensitivity of the solid-phase assay was higher for glycoproteins containing N-acetyl-9-O-acetylneuraminic acid than for gangliosides, and also differed for various 9-O-acetylated gangliosides. The overlay assay was less sensitive for all glycoconjugates tested. For virus recognition the presentation of the sialic acid within the molecule and the structure of the sialic acid are essential. Investigation of gangliosides from human melanomas and normal skin with the influenza C virus assay showed an increase of O-acetylation of sialic acids in most tumour samples and the occurrence of several O-acetylated gangliosides. (+info)
Lectin-binding capacity of glycoconjugates in Escherichia coli 09:K103:NM, 987P+ST+-infected porcine lower small intestines.
(45/567)
Composition of glycoconjugates were investigated in Escherichia coli 09:K103:NM, 987P+ST+-infected lower small intestines of 1-week-old pigs by the use of twenty one biotinylated-labelled lectins with avidin-biotin-peroxidase complex method. Piglets with experimental group were inoculated by feeding 5 ml of culture inoculum (5 x 10(9) colony-forming units/ml) with 15 ml of milk replacer. At the onset of diarrhea, experimental piglets and time-matched control piglets were euthanatized using electrocution, necropsied, and tested by lectin histochemistry. As compared with control, staining intensity of seven lectins altered in ileal villus brush border and goblet cells of pigs inoculated with the pathogen. (+info)
Characterisation of glycoconjugate sugar residues in the vomeronasal organ of the armadillo Chaetophractus villosus (Mammalia, Xenarthra).
(46/567)
Conventional carbohydrate histochemistry and the binding patterns of 21 lectins were analysed to characterise the glycoconjugate content in the components of the vomeronasal organ of the armadillo Chaetophractus villosus. The mucomicrovillous complex of the sensory epithelium bound most of the lectins studied. No reaction was observed with Con A, PSA, S-Con A and SBA, and the sustentacular cells were-stained with UEA-I, DSL, LEL, STL and Con A. The vomeronasal receptor neurons were labelled with S-WGA, WGA, PNA, UEA-I, STL, Con A, S-Con A, ECL and RCA120. The basal cell layer reacted with S-WGA, WGA, LCA, UEA-I, DSL, LEL, STL, Con A, JAC and VVA. The nonsensory epithelium exhibited a differential staining in relation to the different components. The mucociliary complex stained with ECL, DBA, JAC, RCA120, STL, LCA, PHA-E, PHA-L, LEL, BSL-I and VVA. However, SJA and UEA-I stained the mucus complex lining a subpopulation of columnar cells. The cytoplasm and cell membranes of columnar cells was labelled with DBA, DSL and LCA. The apical region of these cells exhibited moderate reactivity with LEL and SJA. None of the lectins bound specifically to secretory granules of the nonsecretory cells. Basal cells of the nonsensory epithelium were labelled with DSL, LEL, LCA, BSL-I and STL. The vomeronasal glands showed a positive reaction with WGA, DSL, LEL, LCA, DBA, PNA, RCA120 and SBA. Subpopulations of acinar cells were observed with ECL, S-WGA, Con A, S-Con A and DBA. PNA and RCA120 stained the cells lining the glandular ducts. In comparison with previous results obtained in the olfactory mucosa of the same group of armadillos, the carbohydrate composition of the vomeronasal organ sensory epithelium differed from the olfactory sensory epithelium. This is probably related to the different nature of molecules involved in the perireceptor processes. (+info)
Sulfated glycoconjugates enhance CD36-dependent adhesion of Plasmodium falciparum-infected erythrocytes to human microvascular endothelial cells.
(47/567)
A novel adhesive pathway that enhances the adhesion of Plasmodium falciparum-infected erythrocytes (IEs) to endothelial cells has been identified. The sulfated glycoconjugates heparin, fucoidan, dextran sulfate 5000, and dextran sulfate 500 000 caused a dramatic increase in adhesion of IEs to human dermal microvascular endothelial cells. The same sulfated glycoconjugates had little effect on IE adhesion to human umbilical vein endothelial cells, a CD36-negative cell line. The effect was abolished by a monoclonal antibody directed against CD36, suggesting that enhanced adhesion to endothelium is dependent on CD36. No effect was observed on adhesion to purified platelet CD36 cells immobilized on plastic. The same sulfated glycoconjugates enhanced adhesion of infected erythrocytes to COS cells transfected with CD36, and this was inhibited by the CD36 monoclonal antibody. These findings demonstrate a role for sulfated glycoconjugates in endothelial adherence that may be important in determining the location and magnitude of sequestration through endogenous carbohydrates. In addition, they highlight possible difficulties that may be encountered from the proposed use of sulfated glycoconjugates as antiadhesive agents in patients with severe malaria. (+info)
Development of conjunctival goblet cells and their neuroreceptor subtype expression.
(48/567)
PURPOSE: To investigate expression of muscarinic, cholinergic, and adrenergic receptors on developing conjunctival goblet cells. METHODS: Eyes were removed from rats 9 to 60 days old, fixed, and used for microscopy. For glycoconjugate expression, sections were stained with Alcian blue/periodic acid-Schiffs reagent (AB/PAS) and with the lectins Ulex europeus agglutinin I (UEA-I) and Helix pomatia agglutinin (HPA). Goblet cell bodies were identified using anti-cytokeratin 7 (CK7). Nerve fibers were localized using anti-protein gene product 9.5. Location of muscarinic and adrenergic receptors was investigated using anti-muscarinic and beta-adrenergic receptors. RESULTS: At days 9 and 13, single apical cells in conjunctival epithelium stained with AB/PAS, UEA-I, and CK7. At days 17 and 60, increasing numbers of goblet cells were identified by AB/PAS, UEA-I, HPA, and CK7. Nerve fibers were localized around stratified squamous cells and at the epithelial base at days 9 and 13, and around goblet cells and at the epithelial base at days 17 and 60. At days 9 and 13, M2- and M3-muscarinic and beta2-adrenergic receptors were found in stratified squamous cells, but M1-muscarinic and beta1-adrenergic receptors were not detected. At days 17 and 60, M2- and M3-muscarinic receptors were found in goblet cells, whereas M1-muscarinic receptors were in stratified squamous cells. Beta1- and beta2-adrenergic receptors were found on both cell types. Beta3-adrenergic receptors were not detected. CONCLUSIONS: In conjunctiva, nerves, M2- and M3-muscarinic, and beta1- and beta2-adrenergic receptors are present on developing goblet cells and could regulate secretion as eyelids open. (+info)