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PubMed1987

The epitope of mouse embryonic antigen(s) recognized by monoclonal antibody TEC-02 is a carbohydrate carried by high-molecular-weight glycoconjugates.

The expression and properties of mouse embryonic antigens, recognized by monoclonal antibody TEC-02, were analyzed in teratocarcinoma-derived cell lines. TEC-2 antigens were found in the majority of the parietal endoderm cells PYS-2 and in a fraction of cultured embryonal carcinoma cells but not in other cell lines tested. During the course of retinoic acid-induced differentiation of embryonal carcinoma cells F9, the expression of TEC-2 was transiently increased. Immunolabeling of extracts from F9 and PYS-2 cells separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that TEC-2 antigens are polydisperse glycoconjugates of high molecular weight (mostly greater than 100,000). The TEC-2 epitope was shown to be carbohydrate which in F9 cells might be attached to the same carrier as another developmentally regulated carbohydrate epitope TEC-1. The TEC-2 antigens, isolated by indirect immunoprecipitation, were degraded by extensive pronase digestion or mild alkaline treatment to mostly large products. Immunostaining of glycolipid standards suggested that TEC-2 epitope involves the GalNAc beta 1----4Gal beta 1----4R sequence. Combined data indicate that TEC-2 is a new developmentally regulated carbohydrate epitope carried in embryonal carcinoma cells predominantly on glycoprotein-bound large carbohydrates.

Animals↗

PubMed1989

The effect of cotton bract extract on respiratory glycoconjugate secretion from human airways in vitro.

In vivo and in vitro studies with a water-soluble extract of cotton bracts (CBE) suggest that CBE may be responsible for some of the clinical manifestations of byssinosis. Since chronic bronchitis has been repeatedly documented as a major feature of byssinosis, we studied the effect of CBE on respiratory glycoconjugate (RGC) release from human airways (HAs) in vitro. HAs were incubated with [3H]glucosamine to label RGC molecules. CBE in increasing concentrations was added to radiolabeled HAs, and the release of 3H-RGC, histamine, and other mediators was measured. CBE in concentrations of 1 to 7 mg/ml caused a dose-related increase in RGC, as well as histamine release (RGC, 14% to 45% increase above control; histamine, 12 to 70 ng/ml released concurrently). Additionally, CBE in a dose of 5 mg/ml caused a more than threefold increase in peptidoleukotriene production above baseline. The effect of histamine H1 and H2 (pyrilamine and cimetidine), cyclooxygenase pathway inhibitor (indomethacin), leukotriene (LY 171883 and FPL 55712), and lipoxygenase pathway (BW nordihydroguaiarectic acid) blocking agents on CBE-induced RCG secretion was studied. In addition to histamine-H1 blockers, lipoxygenase inhibitors (nordihydroguaiarectic acid and BW 755C) and leukotriene blockers (FPL 55712 and LY 171883) are also potent inhibitors of CBE-induced RGC secretion. This suggests that CBE may act via the release of several mediators (histamine and leukotrienes), possibly from airway cells, such as mast cells, macrophages, or epithelial cells, to stimulate RGC secretion.

Bronchi↗

PubMed1989

Platelet-activating factor stimulates secretion of respiratory glycoconjugate from human airways in culture.

Platelet-activating factor (PAF) is a naturally occurring phospholipid that acts as a potent mediator of inflammation and bronchoconstriction. Since mucus secretion accompanies many pulmonary-allergic reactions, we examined the effect of PAF on respiratory glycoconjugate (RGC) release from human airways in vitro. PAF, in concentrations of 5 to 100 ng/ml, induced a specific, dose-dependent release of [3H]RGC from human airways in vitro (range of 15% to 120% increase above control, p less than 0.001; n = 8). Time-course studies revealed that RGC release reached its peak level by 60 minutes, and by the end of 4 hours, decreased almost to the baseline level, suggesting a stimulatory effect on secretion rather than synthesis. PAF analog, RO 19-3704, which is a PAF-receptor antagonist, inhibited RGC secretion mediated by PAF in a dose-dependent manner with an inhibitory concentration of 50% of 70 ng/ml. BW 755C and nordihydroguaiaretic acid, but not indomethacin, inhibited RGC release by PAF. LY 171883, a specific leukotriene D4-receptor antagonist, totally inhibited the release of RGC by PAF. Similar results were observed with FPL 55712. PAF-treated airways generated peptidoleukotrienes significantly above control airways in association with enhanced RGC secretion. This enhanced effect on RGC secretion was specifically and significantly blocked by LY 171883. Atropine (10(-5) mol/L) augmented the secretagogue activity of PAF, whereas dexamethasone (10(-5) mol/L) inhibited it. These data indicate that PAF is a significant RGC secretagogue that affects the RGC-secreting cells via the lipoxygenase pathway of arachidonic acid metabolism and the generation of leukotrienes in the airways, but not through the cholinergic receptors on the secretory cells.

Arachidonic Acids↗

PubMed1992

Isolation and characterization of a macrophage-derived high molecular weight protein involved in the regulation of mucus-like glycoconjugate secretion.

Pulmonary macrophages release a variety of mediators that are involved in inflammatory processes and probably are involved in respiratory mucus secretion. Conditioned media obtained from activated pulmonary macrophages were found to contain a protein that functioned as a secretagogue for mucus-like glycoconjugate (MLGC) in an in vitro bioassay. A human macrophage-derived hybridoma cell line, HB-63, exhibited the same properties and was very useful in obtaining large amounts of the protein for purification and characterization. With ultrafiltration membranes and gel electrophoresis, the protein isolated from the conditioned media of zymosan- or lipopolysaccharide-treated cells was found to have a molecular weight of approximately 68 kd. The purified protein obtained from hybridoma cells and from pulmonary macrophages exhibited strong biologic activity when it was used to stimulate MLGC secretion, both in human airway explants and in an in vitro human secretory epithelial cancer cell line. The proteins from both sources were found to have similar amino acid compositions. Preliminary results indicate the presence of the 68 kd protein in the bronchoalveolar lavage fluid of a patient with severe chronic bronchitis and mucus hypersecretion. The role of this novel protein in the lungs is, so far, speculative. The 68 kd protein may be a useful tool for studying the biosynthesis and regulation of MLGC secretion and hypersecretion.

Amino Acids↗

PubMed1993

In vivo detection of a novel macrophage-derived protein involved in the regulation of nasal mucus-like glycoconjugate secretion.

BACKGROUND: We recently described a novel 68 kd mucus secretagogue (MMS-68) derived from human monocytes, pulmonary macrophages, and a macrophage hybridoma, clone 63. We detected MMS-68 in monocyte culture supernatants from patients with steroid-dependent asthma and in bronchoalveolar lavage fluid from patients with chronic bronchitis by antigen capture ELISA and in normal lung tissue by immunohistochemistry. METHODS: To determine a role for MMS-68 in the regulation of nasal mucus, we labeled human nasal turbinates with tritiated glucosamine and assayed for the ability of the previously purified MMS-68 (stock solution) to induce mucus-like glycoconjugate release (MLGC). We also performed immunohistochemistry stains with an anti-MMS-68 antibody (1-D-10) on frozen sections (n = 5) of nasal turbinates from patients with allergic and nonallergic rhinitis who were undergoing rhinoplasty and measured MMS-68 levels in nasal lavages from patients who were undergoing topical nasal histamine or methacholine challenge. RESULTS: MMS-68 is a potent nasal MLGC secretagogue causing a dose-dependent increase in MLGC release in vitro. Staining revealed a subepithelial distribution for MMS-68. Antigen capture ELISA of nasal lavages demonstrated mean MMS-68 levels from saline control challenge of 0.9 +/- 0.5 micrograms MMS-68 per milligram of protein (n = 5), 8.6 +/- 1.4 micrograms MMS-68 per milligram of protein from histamine challenge and 20.7 +/- 2.3 micrograms MMS-68 per milligram of protein (n = 5) after methacholine challenge. CONCLUSION: Taken together these data suggest that MMS-68 may play a role in the normal regulation of mucus secretion.

Adult↗

PubMed1990

Distribution of VIM-2 and SSEA-1 glycoconjugate epitopes among human leukocytes and leukemia cells.

Anti-SSEA-1 which binds to glycoconjugates with a Gal beta 1-4(fuc alpha 1-3)GlcNAc epitope and VIM-2 which binds to gangliosides with a NeuAc alpha 2-3GlcNAc beta-4(FUC alpha 1-3) GlcNAc beta 1-3Gal-epitope were used to determine the expression of their corresponding carbohydrate antigens in human leukocytes and leukemia cells. Expression of these antigens was evaluated by immunohistochemical staining of plastic embedded sections of bone marrow or isolated cells, and by immunostaining of isolated glycosphingolipids separated by thin layer chromatography. The expression of both antigens was restricted to normal and leukemic myeloid cells. A range of positive immunohistochemical staining was found among normal marrow myeloid precursors, with myeloblasts giving weaker staining than more mature cells (promyelocytes, myelocytes, metamyelocytes). A similar trend was observed with leukemia cell lines, in that the myeloblastic cell line KG1 was weakly stained compared to the partially differentiated cell line HL-60. Immunohistochemical staining of marrows from acute leukemia patients showed that the VIM-2 antigen is more strongly expressed than the SSEA-1 antigen. Interestingly, both antibodies stained AMMoL cells more intensely than AML cells. Granulocytes from marrows of chronic myelogenous leukemia (CML) patients were intensely stained by both antibodies, whereas lymphocytic leukemias (acute lymphocytic, chronic lymphocytic and hairy cell marrows) were negative. Thus, although both antigens are restricted to myeloid cells there are differences in the level of expression depending on the level of cell maturity. Immunostaining of glycosphingolipids isolated from myeloid cells demonstrated that the SSEA-1 epitope is carried by several neutral glycosphingolipids and that the VIM-2 epitope is carried by three or more gangliosides. Major SSEA-1 glycosphingolipids, with seven to more than ten monosaccharides, are expressed by all myeloid cells regardless of the level of maturity, although quantitative differences are apparent in different patient samples. Two strongly immunoreactive VIM-2 gangliosides with ten and twelve monosaccharides, respectively were found in myeloid cells. The ratio of these two gangliosides varied dramatically, with greater amounts of the more complex ganglioside being present in most cell samples. Normal neutrophils and CML cells had much greater quantities of the VIM-2 gangliosides than acute leukemia cells. This observation correlates with our earlier findings that: (1) acute leukemia cells have less total ganglioside than granulocytes and (2) acute leukemia cells have a predominance of short chain gangliosides (i.e. less than five monosaccharide units). Finally, both CML cells and normal neutrophils express a shorter chain VIM-2 ganglioside, which was not detected in acute myelogenous leukemia cells.

Antigens, Surface↗

PubMed1988

Glycoconjugates and cell adhesion: the adhesive proteins laminin, thrombospondin and von Willebrand's factor bind specifically to sulfated glycolipids.

The adhesive glycoproteins laminin, thrombospondin and von Willebrand's factor bind specifically and with high affinity to sulfated glycolipids, and it is this binding that probably accounts for their ability to agglutinate glutaraldehyde-fixed erythrocytes. The 3 proteins differ, however, in the effect of sulfated polysaccharides on their binding to sulfatides. Fucoidan strongly inhibits binding of both laminin and thrombospondin, but not of von Willebrand's factor, suggesting the involvement of laminin or thrombospondin or other unknown sulfatide-binding proteins in specific cell interactions that are also inhibited by fucoidan. Thrombospondin adsorbed onto plastic promotes the attachment and spreading of G361 melanoma cells. Interestingly, fucoidan and an antibody directed against the sulfatide-binding domain of thrombospondin selectively inhibit spreading but not attachment. Sulfatides, but not neutral glycolipids or gangliosides, when adsorbed onto plastic also promote attachment and spreading of G361 melanoma cells. Direct adhesion of G361 cells requires high densities of sulfatide. In the presence of laminin, however, specific adhesion of G361 cells to sulfatide is strongly stimulated and requires only low densities of adsorbed lipid, suggesting that laminin mediates adhesion by cross-linking receptors on the melanoma cell surface to sulfatide adsorbed onto the plastic. Although thrombospondin binds to sulfatide and to G361 cells, it does not enhance but rather inhibits direct and laminin-dependent G361 cell adhesion to sulfatide, presumably because it is unable to bind simultaneously to ligands on opposing surfaces. Thus, sulfated glycoconjugates participate in both laminin- and thrombospondin-mediated cell adhesion, but their mechanisms of interaction are different.

Animals↗

PubMed1992

Miracidium of Schistosoma mansoni: a macromolecular glycoconjugate as signal for the behaviour after contact with the snail host.

1. The behaviour of the miracidium of Schistosoma mansoni after contact with agar blocks containing Biomphalaria glabrata snail conditioned water (SCW) or its components, was studied. 2. "Repeated investigation" was the most specific response at contact with the snail host. 3. Fractionation and specific chemical treatment of SCW revealed that this response was stimulated by a lysozyme sensitive glycoconjugate with a mol. wt greater than 300,000. 4. Low molecular weight components of SCW had no stimulatory effect on the miracidia, although MgCl2 offered as pure chemical did so.

Animals↗

PubMed1987

Binding of specific glycoconjugates to human brain synaptosomes: studies using glycosylated beta-galactosidase.

Using glycosylated beta-galactosidase (beta-gal) as a glycoprotein model, binding of glycoconjugates to human brain synaptosomes was studied. Out of beta-gal modified with a series of p-aminophenyl alpha- or beta-glycosides, beta-gal modified with p-aminophenyl beta-D-glucopyranoside (beta-D-Glc beta-gal) was bound to the synaptosomes most effectively, then beta-gal modified with beta-D-galactoside and with alpha-D-mannoside. Kinetic studies on the binding of beta-D-Glc beta-gal indicated the presence of saturable binding on human brain synaptosomes. The values of the apparent Km and of the maximal binding velocity were obtained to be 248 +/- 32.9 microM and 43.8 +/- 1.43 fmol/min/mg synaptosome protein, at 4 degrees C and pH 7.5. The specificity of the sugar recognition site proved by the competitive inhibition of the binding of beta-D-Glc beta-gal by bovine serum albumin modified with the same glycoside. The binding of beta-gal modified with beta-D-galactoside was inhibited by treatment of the synaptosomes with trypsin, phospholipase A2, C and D, and with neuraminidase, while the binding of beta-D-Glc beta-gal was inhibited by neuraminidase treatment of synaptosomes. In subcellular fractions of human brain the binding protein was localized mainly in synaptosomes.

Cerebral Cortex↗

PubMed1991

Fucosylated glycoconjugates in human dorsal root ganglion cells with unmyelinated axons.

The same subset of small neurons in human dorsal root ganglia (DRG) was recognized by both of the two probes binding to fucosylated residue. Ulex europaeus agglutinin I (UEA-1) lectin and anti-fucosyl GM1 antibody, although these probes bind to different glycoconjugates. UEA-1 lectin also bound to unmyelinated axons in DRG and in biopsied sural nerve, but not to any neurons or unmyelinated axons in the sympathetic ganglia. Thus UEA-1 lectin and anti-fucosyl GM1 antibody may be used as specific probes for primary sensory neurons with unmyelinated axons.

Antibodies↗

PubMed1992

Ultrastructural localization and semiquantitative analysis of glycoconjugates in the tectorial membrane.

The tectorial membrane of the gerbil cochlea was analyzed with lectin-gold cytochemical methods for demonstrating and characterizing glycoconjugates (GCs) in situ. Binding of lectins from Limax flavus (LFA), Lens culinaris (LCA), Datura stramonium (DSA), Ricinus communis (RCA I), Ulex europeus (UEA I) and Phaseolus vulgaris (PHA L) was assayed semiquantitatively on ultrathin sections. Binding occurred throughout the tectorial membrane with all lectins except UEA I but the labelling density with a given lectin differed among substructures. The cover net disclosed the highest level of GC with four lectins whereas the fibrous layer revealed the lowest level. DSA, LCA and PHA L demonstrated considerable similarity between the cover net and the marginal band in content of GC with N-linked oligosaccharide. The cover net differed from the marginal band, however, in containing more RCA I reactive GC with terminal lactosamine. Hensen's stripe, with which inner hair cell stereocilia are thought to interact, differed from other substructures in containing the highest level of PHA L-reactive traintennate N-linked chains and except for the basal layer the lowest concentration of GC with terminal lactosamine. Fucosylated GC detectable with UEA I-gold was present at low levels in all substructures except the cover net and marginal band. Distribution of GCs in the fibrous layer and less consistently in the cover net differed between limbal and middle zones. The differences observed here in the carbohydrate composition among substructures in the tectorial membrane support and extend previous cytochemical observations and imply a role for different classes of GCs in determining the biophysical and physiological properties of the tectorial membrane.

Animals↗

PubMed1993

Glycoconjugates in the cochlea as revealed by the silver methenamine method.

The glycoconjugates in the cochlea of the guinea pig were studied by staining samples by the silver methenamine method as well as after periodic acid-Schiff (PAS) staining. Results obtained by the two methods were similar but not identical. The silver methenamine method was much better in terms of resolution. However, this method of staining seemed less specific than the PAS reaction. When the silver methenamine method was used, the tectorial membrane and outer hair cells were specifically stained. Two types of fibrils were observed in the tectorial membrane. Thick fibrils were located in the fibrous layer. Thin fibrils were situated in the marginal band, the cover net, Hensen's stripe and the fibrous layer. The thick and thin fibrils appeared to correspond to type A and type B protofibrils, respectively. The outer hair cells were found to contain strongly stained particles which, presumably, consisted of glycogen. The basement membrane of the capillaries in the stria vascularis also gave a positive reaction, while that of other capillaries was essentially unstained. This finding suggests structural differences between these capillaries.

Animals↗

PubMed1993

Glycoconjugates in the vestibular organs as revealed by the silver methenamine method.

The glycoconjugates in the vestibular organs of the guinea pig were studied after staining by the silver methenamine method and by the periodic acid-Schiff (PAS) reaction. The organic matrix of otoconia, otolithic membranes and cupulae were stained to the same degree by the PAS reaction. In contrast, the mineralizing and non-mineralizing matrices were clearly distinguished by the silver methenamine method. The otoconia were surrounded by an intensely stained organic matrix, while the otolithic membranes and cupulae were moderately stained. This histochemical difference suggests that the positively stained organic matrix of otoconia is not identical to the otolithic membranes and cupulae in terms of its biochemical composition. The strongly stained material may play an important role in turnover of calcium in otoconia. The contact areas between type I hair cell and nerve calyx were contained silver methenamine-positive material which is probably involved in adhesion of these cell membranes.

Animals↗

PubMed2004

Application of the four-component Ugi condensation for the preparation of sulfated glycoconjugate libraries.

A focused library of novel, sulfated glycoconjugates was synthesized by utilizing carbohydrate-derived blocks in the four-component Ugi condensation. Library members comprise a sulfated monosaccharide linked by various spacers to either an aromatic or monosulfated moiety, or a second sulfated monosaccharide. The affinities of these heparan sulfate (HS) mimetics for the HS-binding fibroblast growth factors FGF-1 and FGF-2 were measured via a surface plasmon resonance solution affinity assay.

Fibroblast Growth Factor 1↗

PubMed2005

Synthesis and NMR characterization of hydroxyurea and mesylglycol glycoconjugates as drug candidates for targeted cancer chemotherapy.

Tumor targeting of glycoconjugated antineoplastic agents is a strategy currently under investigation for cancer chemotherapy. We have synthesized the glucosides and galactosides of the clinically established drug hydroxyurea and of mesylglycol, the reactive moiety of the anticancer drug busulfan. Glycosides of hydroxyurea were obtained by carbamoylation of hydroxylamine glycosides. The glycosides of mesylglycol were synthesized by mesylation of protected glycol glycosides. All compounds were characterized by detailed 1H and 13C NMR analysis.

Antineoplastic Agents↗

PubMed2005

Revised structures for the capsular polysaccharides from Staphylococcus aureus Types 5 and 8, components of novel glycoconjugate vaccines.

Glycoconjugate vaccines based on the capsular polysaccharides (CPSs) from Staphylococcus aureus serotypes 5 and 8 conjugated to genetically detoxified recombinant exoprotein A (rEPA) from Pseudomonas aeruginosa have been shown, in Phase 3 clinical trials, to elicit a strong bactericidal immune response in end-stage renal disease patients. Such vaccines have the potential to reduce morbidity and mortality due to methicillin-resistant Staphylococcus aureus (MRSA), a major cause of hospital-acquired infection. The serotype 5 and 8 polysaccharides have been fully characterized by NMR spectroscopy and full structural analyses carried out. Published structures were found incorrect and the revised structures of the repeat units of the two polysaccharides are: [carbohydrate structure: see text]. Resonances indicative of the presence of peptidoglycan were observed in the spectra of both CPSs, consistent with reports that the CPS is covalently linked to peptidoglycan.

Acetylation↗

PubMed2004

Carbohydrate diversity: synthesis of glycoconjugates and complex carbohydrates.

The fundamental role of glycoconjugates in many biological processes is now well appreciated and has intensified the development of innovative and improved synthetic strategies. All areas of synthetic methodology have seen major advances and many complex, highly branched carbohydrates and glycoproteins have been prepared using solution- and/or solid-phase approaches. The development of an automated oligosaccharide synthesizer provides rapid access to biologically relevant compounds. These chemical approaches help to produce sufficient quantities of defined oligosaccharides for biological studies. Synthetic chemistry also supports an improved understanding of glycobiology and will eventually result in the discovery of new therapeutics.

Glycoconjugates↗

PubMed2004

Characterization of keyhole limpet hemocyanin (KLH) glycans sharing a carbohydrate epitope with Schistosoma mansoni glycoconjugates.

Keyhole limpet hemocyanin (KLH) is known to share carbohydrate epitopes with Schistosoma mansoni. In order to define the structural basis for the observed serological cross-reactivity, KLH glycans were released either by enzyme treatment or by hydrazinolysis and probed with a rabbit hyperimmune serum directed against S. mansoni egg antigen. Both major, non-reacting oligosaccharide species as well as the minor compounds recognized were isolated by two-dimensional high performance liquid chromatography and in part by lectin affinity chromatography, and characterized by mass spectrometry. The results revealed that KLH carries predominantly high mannose-type glycans as well as short sugar chains. As a characteristic feature, a number of the latter glycans contained a Gal(beta1-6)Man-unit, which has not yet been found in glycoprotein-N-glycans. Oligosaccharides cross-reacting with schistosomal glycans comprised a terminal Fuc(alpha1-3)GalNAc-motif, which appears to represent the main carbohydrate epitope mediating cross-reactivity of KLH with glycoconjugates from S. mansoni.

Animals↗