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PubMed1991

Histochemical localization of glycoconjugates in the palmar aponeurosis of Dupuytren's patients.

Acridine orange added to the primary fixative or reduced osmium tetroxide as postfixative have been used in order to localize by thin section electron microscopy glycoconjugates in the extracellular matrix of the normal palmar aponeurosis as well as in tissues at different stages of Dupuytren's contracture. After use of acridine orange or reduced osmium tetroxide, in the nodule of the active stage an extensive network of fine filaments separated single or small bundles of collagen fibrils from each other. In the cord of the residual stage fixed in presence of acridine orange, the tightly packed collagen fibrils in the central region of the specimens were swollen and had stained material interposed between the single microfibrils. In specimens of the same cord first fixed with glutaraldehyde alone, followed by reduced osmium tetroxide, the disaggregation of collagen fibrils could be seen only occasionally and the intrafibrillar stained glycoconjugates were less evident. Comparable alterations were absent from the normal tissue. The possible reasons of these differences are discussed.

Acridine Orange↗
PubMed1986

Use of synthetic glycoconjugates containing the Mycobacterium leprae specific and immunodominant epitope of phenolic glycolipid I in the serology of leprosy.

The high specificity of phenolic glycolipid I (PG-I) in the identifying individuals with leprosy appears to be attributable to the species-specific trisaccharide region of the molecule. Synthetic glycoconjugates were produced by coupling the corresponding terminal mono- or disaccharide to bovine serum albumin by reductive amination. Conjugates which contained only the terminal sugar maintained in its pyranose form, the terminal disaccharide with only the terminal sugar in its pyranose form and the terminal disaccharide with both the 3,6,di-o-Me-glucose and 2,3,di-o-Me-rhamnose sugars in their pyranose forms, were all highly active in the enzyme-linked immunosorbent assay (ELISA) and showed good concordance with native PG-1 in analysis of sera from leprosy patients. The antibody levels to the glycoconjugates in tuberculosis patients and patients with other mycobacterial infections were not significantly different from the levels in normal healthy control subjects. A few of the leprosy sera showed much stronger binding to conjugates which contained the disaccharide with both sugars in the pyranose form than to conjugates with only the terminal sugar in its pyranose form. Therefore a synthetic conjugate which contains the intact disaccharide region of PG-I may provide the most sensitive antigen for the large scale serodiagnosis of leprosy.

Antibodies, Bacterial↗
PubMed1987

Characterization of five Shigella flexneri variant Y-specific monoclonal antibodies using defined saccharides and glycoconjugate antigens.

The structural domains of the Shigella flexneri variant Y O-antigen epitopes 3,4 have defied definition, despite knowledge of the structure of the linear polysaccharide chain of the LPS molecule. The dual epitope designation of group antigen 3,4 is based on absorption data using polyvalent rabbit antisera. Five monoclonal antibodies specific for the Y antigen, generated after immunization of BALB/c mice or LOU/C rats, were selected on the basis of ELISA by using well-characterized S. flexneri Y LPS and chemically defined glycoconjugates. Chemically defined LPS from all S. flexneri serogroups, synthetic oligosaccharides, and saccharides obtained by phage Sf6-mediated hydrolysis of the O-polysaccharide were used either as free haptens or glycoconjugates in Farr assays and ELISA titrations. Two different patterns of antibody specificities were seen: two monoclonal antibodies had combining sites recognizing the terminal nonreducing end of the O-polysaccharide complementary to the tetrasaccharide repeating unit; and three antibodies bound to intrachain determinants and had larger combining sites, possibly accommodating at least an octasaccharide. The precise specificity of these two general types of antibodies indicate that variant Y polysaccharide generates more than two O-factors.

Animals↗
PubMed1986

In vitro attachment of mono- and oligosaccharides to surface glycoconjugates of intact cells.

We have synthesized glycosylhydrazines of various mono- and oligosaccharides and coupled these to periodate- or galactose oxidase-treated human red cells and K562 erythroleukemia cells. The optimal conditions for this carbohydrate modification of cells have been established. This method makes it possible to specifically elongate oligosaccharide chains of cell surface glycoconjugates with desired carbohydrates. In this way, new antigenic and receptor properties can be conferred to cells, and the functional roles of carbohydrates in cell surface glycoconjugates can be studied. The method has been used to make red cells of blood group O reactive with anti-A and anti-B sera, and in rendering K562 cells or red cells of blood group O agglutinable with the alpha-N-acetylgalactosamine-specific Helix pomatia lectin.

ABO Blood-Group System↗
PubMed1987

Surface glycoconjugates on rat photoreceptor cilium. Effect of neuraminidase digestion.

In retinal photoreceptors the connecting cilium constitutes a boundary between the inner and outer segments. In previous studies we demonstrated that, while opsin could be localized in abundance in the distal ciliary membrane, very little opsin was detected in the proximal ciliary plasma membrane. In the present study we extended our view of molecular specialization on the ciliary membrane with respect to glycoconjugates. Saccharide moieties of ciliary glycoconjugates were studied in immature and mature rat photoreceptors. Surface saccharides were detected and localized by means of ferritin-labeled lectins and electron microscopy. Dense labeling of the ciliary membrane surface with wheat germ agglutinin (WGA) was observed. In immature photoreceptors the labeling was restricted to the proximal ciliary membrane, in a region where opsin molecules could not be detected. Neuraminidase digestion abolished WGA binding to the proximal ciliary membrane surface, indicating that sialic acids mediate WGA binding to this domain. Peanut agglutinin (PNA) did not label the ciliary surface, nor did it bind to the surface of other photoreceptor domains. Neuraminidase digestion exposed numerous PNA binding sites on the ciliary membrane surface. In view of the carbohydrate specificity of PNA, we suggest that a terminal trisaccharide sequence, sialic acid-galactose-(beta 1----3)-N-acetyl galactosamine, is present in high density on the proximal ciliary membrane surface.

Animals↗
PubMed1986

Alterations in stromal glycoconjugates in macular corneal dystrophy.

Nine biotinylated lectins were used as histochemical probes to localize the carbohydrates residues of glycoconjugates in normal corneas and in corneas with macular and granular dystrophy. The lectin binding patterns of normal corneas and of corneas with granular dystrophy were indistinguishable from one another, but were distinctly different from those found in corneas with macular dystrophy. Concanavalin A reacted weakly with normal corneal stromal matrix, but stained stromal matrix of corneas with macular dystrophy intensely. Furthermore, unlike the normal corneal matrix, stromal matrix of corneas with macular dystrophy reacted positively with wheat germ agglutinin (WGA), Ricinus communis agglutinin I (RCA-I), Ulex europeus I, Dolichos biflorus, Bandeiraea simplicifolia I, Bandeiraea simplicifolia II, and soybean and peanut lectins. This study demonstrates specific alterations in glycoconjugates which occur in the corneal matrix of patients with macular dystrophy, namely the presence of oligosaccharides with terminal alpha-fucose, beta-galactose, N-acetylglucosamine and N-acetylgalactosamine residues, and oligosaccharide chains with a beta-galactose-N-acetylgalactosamine sequence.

Adult↗
PubMed1986

Characterization of Shigella flexneri-specific murine monoclonal antibodies by chemically defined glycoconjugates.

Chemically defined glycoconjugates are demonstrated to have considerable potential for selecting hybridoma antibodies directed toward O-antigenic determinants, especially when used in combination with a panel of well-characterized LPS molecules. Monoclonal antibodies specific for the Shigella flexneri O-antigens of serogroup 5b, variants X and Y, were generated after immunization of BALB/c mice with killed bacterial cells, and active hybrids were selected on the basis of ELISA performed with the purified serotype-specific LPS antigen. Subsequent screening with a variety of glycoconjugates, derived from synthetic oligosaccharides and larger structures obtained by phage Sf6/endo-rhamnosidase hydrolysis of purified LPS established a detailed profile of binding characteristics for Shigella flexneri variant Y-specific antibodies. Together with the results of precipitin analysis and heavy chain isotyping experiments, a limited number of antibodies were selected as candidates for detailed studies of the antibody combining site.

Animals↗
PubMed1987

[Phenotypic expression of glycoconjugates in cancer cells].

The carbohydrate moieties of glycoconjugates are thought to represent phenotypic variations in cancer cells most characteristically. In order to raise monoclonal antibodies recognizing these carbohydrate structures, Balb/c mice were immunized with human colonic cancer cell lines (LS 180 and SW 1116), and carbohydrate-directed antibodies were assayed using plastic plates coated with glycopeptides derived from cell surface glycoproteins of the cancer cells used for the immunization. Nine hybridoma clones have so far been established which were classified into four types based on their binding specificity: those binding only to mucin-type carbohydrates, those binding to all types of carbohydrates, i.e., mucin-type, serum-type carbohydrates and glycolipids, those binding to mucin-type carbohydrates and glycolipids, and those binding to serum-type carbohydrates and glycolipids. Another type of classification was also possible based on the involvement of sialic acid in the epitope: those in which removal of sialic acid abolishes the antigenicity, those in which removal of sialic acid enhances the antigenicity, and those in which sialic acid does not affect the antigenicity. The epitopic carbohydrate was identified as NeuAc alpha 2----6GalNAc for one of the antibodies, MLS 102, belonging to category. This is a heterophile antibody reacting strongly with ovine submaxillary mucin having a polyvalent antigenic structure. It was possible to stain colonic cancer cells with the antibodies differentially. Using two types of monoclonal antibodies, it was also possible to stain differentially clones constituting the cell line LS 180. The occurrence of at least four clones could be demonstrated. Such cell-staining capacities of the carbohydrate directed antibodies imply the importance of glycoconjugate carbohydrates as cancer cell phenotypes.

Antibodies, Monoclonal↗
PubMed1979

[The plasma membrane glycoconjugates of normal and transformed cells (author's transl)].

After having reviewed the importance of glycoconjugates in the organisation of the cell membrane and the multiple roles played by these membrane constituants, the disorders characteristics of malignant transformation are described : First, the changes affecting cellular properties (diminution of cellular adhesivity, abolition of the control of cell growth, disturbance of membrane permeability...) and second, the modifications concerning the glycoconjugates of the cell surface in the course of malignant transformation : alterations affecting membrane glycolipids and glycoproteins. It appears that certain modifications of glycannic structures of membrane glycoproteins, for whatever cell type and transforming agent, seem at the moment to constitute the only abnormality permanently associated with the tumorigenicity of malignant cells.

Animals↗
PubMedDate not supplied

Brain glycoconjugates in alcohol and narcotic research.

The glycoconjugates may be divided into three major groups: glycolipids, glycosaminoglycans and glycoproteins. The brain contains a considerable amount of glycolipid and smaller but appreciable amounts of glycoproteins and glycosaminoglycans. The alterations of the brain glucoconjugates found in conditions which affect brain function have not been extensively studied. Alcohol intoxication has been reported to increase the ganglioside content of rat brain. On the other hand lowered gangliosides and glycoproteins have been noted in brain tissue of a human alcoholic. The sialic acid levels associated with gangliosides and with glycoproteins both decreased in morphine dependent rats after withdrawal of the drug. Chronic administration of lithium increased the amount of hyaluronic acid in the cerebellum of rats, but did not affect the chondroitin sulfate level. Further investigation of the glycoconjugates as affected by alcohol and other drug abuse may provide explanations for some of the changes in brain function in these conditions.

Alcoholism↗
PubMed1984

[Localization of glycoconjugates in the tissue structures of man and animals].

By means of concanavalin A (Con A) labelled with fluorescein isotiocyonate in cryostate sections of some human and animal organs (skin, heart, thymus) localization of clycoconjugates containing hexoses and reacting with this lectin has been studied. Glycoconjugates are revealed along the periphery of all cellular elements, in Z-lines and in intercalated disks of the myocardial muscle fibers, in the connective tissue ground substance and also in that of the basal membranes of epithelium, endothelium, muscle fibers (sarcolemma), in cytoplasm of epithelioreticulocytes of the thymus. In fibroblasts of the L-cells culture, glycoconjugates are also localized in cytoplasm. When N-acetylglucosamin is added to the labelled Con A solution, the ability of lectin to react with tissue components is inhibited.

Animals↗
PubMed1981

[Biosynthesis of glycoconjugates in the arterial wall. The role of derivatives of isoprenic pathways and of complex lipids in the glycolization of macromolecules of the intima media].

Previous investigation have shown the occurrence of glycosyl-transferases in the intima-media cells of aortic wall. Some of these enzymes have been isolated from cell-sap as xylosyl-transferase and galactosyl-transferase involved in glycoproteins and glycosamino-glycurono-glycans biosynthesis. Others are located in microsomal fraction as mannosyl-transferase which catalysed polyprenic glycoconjugates biosynthesis. Study of linear and cyclic isoprenic compounds such as squalene and cholesterol, lipidic compounds as sphingolipids and glycerophospholipids and shows their important role as effectors in glycoconjugates biosynthesis regulation; while none of them are intermediates in glycosylation reaction. These lipidic effectors have no effect on substrate-stability nor on ionic reactional parameters. At the opposite, they seem to act in a similar way as non ionic detergents.

Animals↗
PubMed1994

[A histochemical study on the acidic glycoconjugates of the synovial membrane in rheumatoid arthritis].

The localization and the nature of glycosaminoglycans (GAGs) in the synovial membrane in 30 patients with rheumatoid arthritis (RA) involving 40 knees were studied by newly developed histochemical methods. To detect the acidic glycoconjugates, sensitized diamine procedures were employed based upon high and low iron diamine stainings. To identify the various molecular species of the GAGs, enzyme (chondroitinase ABC and B, testicular hyaluronidase and keratanase) digestion and chemical modification (nitrous acid treatment) procedures were performed prior to the diamine stainings. The sensitized diamine methods could clearly stain the acidic glycoconjugates contained in the synovial tissue components in shades of brown to black, and could detect the precise distribution patterns of the GAGs. The results obtained in the present study confirmed that the tissue in RA synovial membranes contained various amounts of each GAG molecular species such as dermatan sulfate, chondroitin sulfate A/C, hyaluronic acid and heparan sulfate. Furthermore, the distribution patterns of dermatan and chondroitin sulfates in the diseased synovial tissues were pathophysiologically interesting; in the inflammatory areas, the molecular species of GAGs was primarily dermatan sulfate, whereas in the fibrotic areas, it was mainly chondroitin sulfate A/C. Such results appear to be useful for pathophysiological studies on the synovial tissues of RA.

Adult↗
PubMed1993

Methionine-enkephalin related glycoconjugates. Synthesis and biological activity.

A series of glycoconjugates, in which [Met5]enkephalin or [D-Ala2,Met5]enkephalin have been linked through an ester bond to the HO-6 of various D-glycopyranose moieties, were synthesized by classical solution methods. The biological activities of these compounds were determined on selective pharmacological preparations: guinea pig ileum and mouse vas deferens for opioid activity, and two mouse cell lines, fibroblasts L929 and melanoma B16BL6, to study the influence on growth processes. The results reported in this study demonstrate the differential effect of the carbohydrate part in enkephalin-related glycoconjugates on receptor recognition. In addition, synthesized neo-glycopeptides stimulate growth of the examined mouse cell lines, whereas parent peptide demonstrated some growth inhibitory properties. Full growth curves showed a dose-dependent effect at concentrations of 10(-7) to 10(-10) M.

Amino Acid Sequence↗
PubMed1996

[Cancer-associated alterations of glycoconjugates--special reference to glycosphingolipids].

Glycoconjugates show the dramatic alterations of the carbohydrate structures in association with oncogenic transformation of the cells. Since glycoconjugates on the cell surfaces are involved in the cellular recognition and response, the structural changes of the carbohydrate in the cancer cells seemed to be closely related to the cell-cell adhesion, cell growth, cell behavior and metastatic property. One of the characteristic changes of glycosphingolipids in association with the oncogenic transformation is oncofetal change, and the other is the molecular mimicry of the glycosphingolipids to those in the cells of immune system. These phenomena indicate how the cancer cells smartly escape the immune surveillance system of the host. In this chapter, cancer-associated changes of glycosphingolipids together with glycolipid synthetase are summarized, and also our recent work on glycosphingolipids in metastatic tumor cells is introduced.

Carbohydrate Sequence↗
PubMed1997

Quantitation and histochemical localization of galectin-1 and galectin-1-reactive glycoconjugates in fetal development of bovine organs.

The display of cellular oligosaccharide chains is known to undergo marked developmental changes, as monitored histochemically with plant lectins. In conjunction with endogenous lectins respective ligand structures may have a functional role during fetal development. The assumption of a recognitive, functionally productive interplay prompts the study of the expression of a tissue lectin and of lectin-reactive glycoconjugates concomitantly. Focusing on common beta-galactosides as constituents of oligosaccharide chains and the predominant member of the family of galectins in mammals, namely galectin-1, the question therefore is addressed as to whether expression of lectin and lectin-reactive glycoconjugates exhibits alterations, assessed in three morphologically defined fetal stages and in adult bovine organs. Using a sandwich ELISA, the level of the rather ubiquitous galectin-1 is mostly increased in adult organs relative to respective fetal stages, except for the case of kidney. This developmental course is seen rather seldom, when the amounts of lectin-reactive glycoproteins or glycolipids are quantitated in solid-phase assays after tissue homogenization. Western blotting, combined with probing by labeled galectin-1, discloses primarily quantitative changes in the reactivity of individual glycoproteins. Performing the same assays on extract aliquots with a plant agglutinin, namely the galactoside-binding mistletoe lectin, whose fine specificity is different from galectin-1, its reduced extent of binding in solid-phase assays and the disparate profile of lectin-reactive glycoproteins reveal a non-uniform developmental alteration within the group of structural variants of beta-galactosides. Although sample preparation can affect ligand preservation and/or presentation and thus restricts the comparability of biochemical and histochemical results, especially for soluble reactants, the histochemical studies on frozen and paraffin-embedded sections of bovine heart, kidney and liver demonstrate that the localization of the galectin and of lectin-reactive epitopes can show a similar distribution, as seen in liver and heart, with organ-typical quantitative changes of a rather similar staining profile (heart, kidney) or notable changes in the spatial distribution (liver) in the course of development. This report emphasizes the potential value of combined monitoring of the lectin and its potential in vivo ligands to contribute to eventually unravel organ-related function(s) of a tissue lectin.

Animals↗
PubMed1996

Extracellular matrix in tooth cementum and mantle dentin: localization of osteopontin and other noncollagenous proteins, plasma proteins, and glycoconjugates by electron microscopy.

BACKGROUND: Noncollagenous proteins (NCPs) are considered to have multiple functions related to the formation, turnover, and repair of the collagen-based mineralized tissues. Collectively, they comprise a class of generally acidic, mineral-binding proteins showing extensive posttranslational modifications, including glycosylation, phosphorylation, and sulfation. METHODS. We have used colloidal-gold immunocytochemistry and lectin-gold cytochemistry, together with transmission electron microscopy, to examine the organic matrix composition of tooth cementum and the subjacent mantle dentin in rodent molar teeth. Molars were processed for immunocytochemistry using antibodies against osteopontin (OPN), osteocalcin (OC), bone sialoprotein (BSP), bone acidic glycoprotein-75 (BAG-75), albumin (ALB), and alpha 2HS-glycoprotein (alpha 2HS-GP), or for glycoconjugate cytochemistry using lectin-gold complexes. RESULTS: Ultrastructurally, at the advancing root edge in developing molars, OPN and BSP initially were associated with small calcification foci in the mantle dentin. With progressing mineralization, OC and alpha 2HS-GP appeared diffusely distributed throughout the calcified mantle dentin, and diminished as a gradient toward the circumpulpal dentin. Immediately following disruption of Hertwig's epithelial root sheath, cementum deposition commenced at the root surface occasionally with the appearance of a cement line rich in OPN. Cementum matrix proper contained abundant OPN, BSP, OC, and alpha 2HS-GP, but no or little BAG-75 or ALB. Protein immunolabeling, as well as lectin labeling for beta-D-galactose and N-acetyl-neuraminic acid and/or N-glycolyl-neuraminic acid, both being prominent sugars of certain NCPs, was primarily concentrated between, and at the surface of, collagen fibrils in acellular extrinsic fiber cementum. OPN, BSP, OC, and alpha 2HS-GP were also prominent components of cellular cementum and of Sharpey's fibers. In cellular cementum, laminae limitantes sometimes present delimiting cementocyte lacunae and cell process-containing canaliculi were also rich in OPN. Along the root surface, occasional cementoblasts exhibited intracellular labeling for OPN over the Golgi apparatus and secretory granules. CONCLUSIONS: We have identified OPN, BSP, OC, and alpha 2HS-GP as being prominent organic constituents of both mantle dentin and acellular and cellular cementum, and, have elucidated the details of their distribution at the ultrastructural level. The temporal appearance and spatial distribution of these organic moieties in the teeth root are similar to those seen during bone formation and are consistent with proposals that certain NCPs may be involved in regulating calcification and/or participating in cell-matrix and matrix-matrix/mineral adhesion events.

Animals↗
PubMed1997

Seasonal variations in integumental glycoconjugates of Rana rugosa.

BACKGROUND: Although environmental conditions can influence the expression of glycoconjugates (GCs) in the epidermis and cutaneous gland of amphibians, seasonal features regarding GCs in frogs have rarely been studied. In the present study, we report the seasonal variations of the integumental GCs in Rana rugosa. METHODS: GCs were investigated at the light microscopic level using conventional and lectin histochemistry. RESULTS: During the pre- through posthibernating periods, stronger periodic acid-Schiff (PAS)-positive GCs were observed in the stratum corneum and transitional layer of the epidermis. At the same time, alcian blue and PAS-positive GCs filled the lumen of the mucous gland. The affinity for PNA in the transitional layer, UEA-1 in stratum germinativum, and SBA in the mucous glands increased significantly during the same periods. In addition, new GCs, which are specific for SBA in the stratum corneum, BSL-1, RCA-1, sWGA, and LCA in some cells of the transitional layer, were detected. CONCLUSIONS: Elevated GCs and a diversity of lectin affinities may be a result of seasonal adaptations related to hibernation. An affinity for PNA, UEA-1, and SBA in the frog skin may be useful as a marker of seasonal changes.

Animals↗