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PubMed1990

Effect of glycoconjugates on rod outer segment phagocytosis by retinal pigment epithelial explants in vitro assessed by a specific double radioimmunoassay procedure.

Rod outer segment (ROS) phagocytosis by explanted bovine retinal pigment epithelium (RPE) was evaluated by a procedure using an indirect double radioimmunoassay which distinguished between ROS attached to the RPE cell surface and those which had been ingested. This approach has been used to investigate the effect of a variety of glycoconjugates on the phagocytic process. Inclusion of the glycosaminoglycans (GAGs) chondroitin sulphate type-A (CS-A) and type-C (CS-C), hyaluronic acid (HA) or dermatan sulphate (DS) in the incubation medium significantly inhibited the ingestion phase of ROS phagocytosis, whereas the binding phase was inhibited to a lesser extent. The interphotoreceptor matrix (IPM), containing these GAGs as part of proteoglycans, also had an inhibitory effect on phagocytosis. The free monosaccharides mannose, fucose and galactose all stimulated the ingestion of ROS by RPE cells. These findings support the suggestion that glycoconjugates may have a physiological role in the photoreceptor renewal process.

Animals↗
PubMed1997

A study of glycoconjugates in nasopharyngeal carcinoma with correlation to clinical transformation.

Little is known about the glycoconjugate changes in human nasopharyngeal epithelium following neoplastic changes. Glycoconjugate histochemistry (Glycine maximus (SBA), Griffonia simplicifolia II (GSA-II), Ulex europaeus (UEA-I), Arachis hypogaea (PNA) and Canavalia ensiformis (ConA)) were performed on the following nasopharyngeal biopsies: 10 adenoid tissues (benign controls), 10 chronic inflammation, 20 squamous metaplasia, 20 undifferentiated carcinoma and 5 squamous cell carcinoma. These results were correlated with the clinical transformations findings. Strong ConA and PNA staining (after neuraminidase treatment (NA)) characterized a subpopulation of squamous metaplasia subjects who later transformed to nasopharyngeal carcinoma. Strong ConA and PNA (before and after NA) depicted the majority of undifferentiated carcinoma subjects having local recurrence following irradiation therapy. In squamous metaplasia, ConA and PNA (after NA) staining may serve as a warning sign for neoplastic changes. Strong stainings for ConA and PNA (before and after NA) in undifferentiated carcinoma subjects may predict a risk for local recurrence.

Carcinoma, Squamous Cell↗
PubMed1997

Glycoconjugate saccharidic moieties of the exocrine and endocrine pancreas in the chick embryo, newborn and adult.

A battery of horseradish peroxidase-conjugated lectins (PNA, SBA, DBA, WGA, ConA, LTA and UEAI) was used to study the distribution of glycoconjugate sugar residues in the exocrine and endocrine pancreas of chick embryos, 1-day-old chicks and adult animals. During the period of incubation considered here, the time of appearance and changes in the oligosaccharides were noted in the acinar cells, in the endocrine cells of the "light islets" and in the capillary endothelial cells. In the developing exocrine pancreas, the basolateral surface of the acinar cells reacted with PNA, WGA, LTA and ConA for the entire period of incubation while SBA, WGA, LTA and ConA reactivity was detected in the apical plasma membrane. Zymogen granule membrane reacted with PNA, WGA and LTA from the 12th day onward, while ConA reactivity was detectable from the 7th day onward. Owing to its early appearance, alpha-D-mannose, revealed by ConA lectin, might in some way contribute to the maturation of the zymogen granule. In the 1-day-old chick and in the adult the cellular surface reacted with WGA and ConA. The zymogen granule membrane reacted with PNA, WGA and ConA in the 1-day-old chick. In the adult, WGA and ConA reactivity was observed in the zymogen granule membrane, whereas at this site PNA reactivity was revealed only after neuraminidase digestion. The hypothesis formulated by others that granule membrane lectin reactivity is equal to the apical membrane reactivity, owing to exocytotic processes, is not consistent with our results in the chick embryos, the 1-day-old chick and the adults. The surface and the granules of the islet beta cells in different periods of incubation reacted with WGA, SBA and, after neuraminidase treatment, with PNA. The same reactivity was seen also in 1-day-old chick while in the adult the granules of the beta cells also reacted with ConA. These findings show the achievement of an almost adult-like state of glycosylation of the glycoconjugates in the beta cells at an early stages of development.

Aging↗
PubMed2006

Characterization of functional oligosaccharide mimics of the Shigella flexneri serotype 2a O-antigen: implications for the development of a chemically defined glycoconjugate vaccine.

Protection against reinfection with noncapsulated Gram-negative bacteria, such as Shigella, an enteroinvasive bacterium responsible for bacillary dysentery, is mainly achieved by Abs specific for the O-Ag, the polysaccharide part of the LPS, the major bacterial surface Ag. The use of chemically defined glycoconjugates encompassing oligosaccharides mimicking the protective determinants carried by the O-Ag, thus expected to induce an efficient anti-LPS Ab response, has been considered an alternative to detoxified LPS-protein conjugate vaccines. The aim of this study was to identify such functional oligosaccharide mimics of the S. flexneri serotype 2a O-Ag. Using protective murine mAbs specific for S. flexneri serotype 2a and synthetic oligosaccharides designed to analyze the contribution of each sugar residue of the branched pentasaccharide repeating unit of the O-Ag, we demonstrated that the O-Ag exhibited an immunodominant serotype-specific determinant. We also showed that elongating the oligosaccharide sequence improved Ab recognition. From these antigenicity data, selected synthetic oligosaccharides were assessed for their potential to mimic the O-Ag by analyzing their immunogenicity in mice when coupled to tetanus toxoid via single point attachment. Our results demonstrated that induction of an efficient serotype 2a-specific anti-O-Ag Ab response was dependent on the length of the oligosaccharide sequence. A pentadecasaccharide representing three biological repeating units was identified as a potential candidate for further development of a chemically defined glycoconjugate vaccine against S. flexneri 2a infection.

Amino Acid Sequence↗
PubMed1999

Tryptophan glycoconjugates in food and human urine.

Evaluating the formation of tryptophan glycoconjugates other than well-established Amadori rearrangement products, HPLC-tandem MS (MS/MS) analysis of human urine collected from several healthy individuals proved the presence of one distinct tryptophan C-glycosyl compound [Horiuchi, Yonekawa, Iwahara, Kanno, Kurihara and Fujise (1994) J. Biochem. (Tokyo) 115, 362-366]. After isolation, unambiguous identification of this novel tryptophan metabolite as 2-(alpha-mannopyranosyl)-l-tryptophan was achieved by tandem MS combined with NMR spectroscopy including homonuclear COSY, heteronuclear multiple-bond connectivity and (1)H-detected heteronuclear multiple-quantum coherence experiments. Remarkably, a thorough evaluation of vicinal proton-proton coupling constants in different solvents and nuclear Overhauser effect experiments demonstrate the predominant axial orientation of the hydroxymethyl group of the hexopyranosyl residue. Likewise this spatial arrangement indicates that the respective alpha-anomeric C-mannosylhexopyranose is preferentially adopting a (1)C(4) conformation in acidic methanol. Whereas only one distinct tryptophan mannoconjugate could be observed in human urine, HPLC-MS/MS analysis of food samples for the first time led to the identification of numerous N(1)-(beta-d-hexopyranosyl)-l-tryptophan, 2-(beta-d-hexopyranosyl)-l-tryptophan and 1-(1,2,3,4,5-pentahyd- roxypent-1-yl)-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid derivatives derived from the condensation of tryptophan with aldohexoses. Taking into consideration the significant differences between profiles and configurations of tryptophan glycoconjugates originating from dietary sources and human urine, C-2 mannosylation of tryptophan residues [de Beer, Vliegenthart, Loeffler and Hofsteenge (1995) Biochemistry 34, 11785-11789] represents a novel enzymic pathway in tryptophan metabolism in humans.

Chromatography, High Pressure Liquid↗
PubMed2000

Carbohydrate-carbohydrate interaction: zymosan and beta-glucan from Saccharomyces cerevisiae bind mannosylated glycoconjugates.

Zymosan from cell wall of the yeast Saccharomyces cerevisiae was found to interact with synthetic and natural glycoconjugates; mannose-rich glycoprotein N-chains demonstrated the maximal affinity. The carbohydrate-carbohydrate nature of the interaction has been confirmed by the following data: 1) periodate treatment of the zymosan impairs the binding; 2) neither protease nor alkali treatment of the zymosan weaken the binding; 3) beta-glucan from S. cerevisiae, which is the major zymosan component, interacts with glycoconjugates similarly to zymosan. The binding is reversible, Ca2+-dependent, and cooperative; it can be dose-dependently inhibited by saccharides relative to one of the partners of the carbohydrate-carbohydrate interaction.

Calcium↗
PubMed2001

[Physico-chemical properties and activity of glycoconjugate LbGp2 from Lycium barbarum L].

AIM: To isolate and purify a glycoconjugate (LbGp2) from the fruit of Lycium barbarum L. and study its immunoactivity and antioxidative activity. METHODS: By means of gel permeation chromatography, LbGp2 was purified. Based on HPLC, CE, GC, SEC and component analysis and so on, its physico-chemical properties were studied. RESULTS: Molecular weights of LbGp2 was 68.2 ku and its carbohydrate content was up to 90.7%. Component analysis showed that it composed of Ara and Gal in a molar ratio of 3:4, and 18 kinds of amino acids. The immunologic function and bioactivity of Lbp2 has been studied preliminarily. Lbp2 was shown to increase rate of phagocyticaction and phagocytic index, promote lymphocyte translation and accelerate the production of serum hemolysin. LbGp2 has distinct effect of antioxidation and the superoxide anion produced by DMSO-NaOH system was scavenged effectively. CONCLUSION: LbGp2 was shown to be a kind of homogeneous glycoconjugate with good immunoactivity and antioxidative activity.

Adjuvants, Immunologic↗
PubMed2001

[Structure elucidation of glycan of a glycoconjugate SPPA-1 isolated from Spirulina platensis].

AIM: To elucidate the structure of the glycan of SPPA-1, a glycoconjugate isolated from Spirulina platensis. METHODS: Methylation analysis, GC/MS, and 1D, 2DNMR techniques were used to determine the structures of the glycoconjugate (SPPA-1). RESULTS: SPPA-1 was only composed of alpha-D-glucose and shown to be a (1-->4) linked alpha-D-glucan to which a few glucosyl side chains are attached at O-6 of the glucosyl residues of the main chain. CONCLUSION: The glycan of SPPA-1 is a new glucan.

Cyanobacteria↗
PubMed1992

Sulfated glycoconjugates demonstrated in combination with high iron diamine thiocarbohydrazide-silver proteinate and silver acetate physical development.

Sulfated glycoconjugates in epithelial cells and mesenchymal cells were investigated after staining with high iron diamine-thiocarbohydrazide-silver proteinate. One purpose of the experiment was to apply a new physical developed to the staining. Instead of silver nitrate, silver lactate or silver bromide, we used silver acetate as an ion donor. This new method allowed physical development under normal lighting conditions, and resulted in the reduction of background staining even after amplification. As the developer did not contain gum arabic, troublesome treatment was not necessary. The time required for staining was very short and the electron density of the final reaction product was high and easily identifiable under the electron microscope. Fixing was not necessary. Very small amounts of reactive substance were detectable after physical development. This developmental procedure has been applied to both the preembedding staining and postembedding staining of sulfated glycoconjugates. The results obtained using this method are presented.

Acetates↗
PubMed1992

Hemostatic activity of the bovine parotid gland glycoconjugates.

The bovine parotid gland was studied by means of biochemical analyses and the glycoconjugates extracted were used to investigate the activity on the human hemostatic system. Thromboelastography was unable to reveal anticoagulant properties. Conversely, the Thrombin Time (TT) was prolonged in a statistically significant way and with dose-coupling response. Reptilase Time (RT) was affected by the highest concentration of extract suggesting that the bovine parotid glycoconjugates alter the fibrinogen polymerization.

Animals↗
PubMedDate not supplied

The oligosaccharidic content of the glycoconjugates of the prepubertal descended and undescended testis: lectin histochemical study.

The saccharidic content of the glycoconjugates has been studied in the descended the undescended testes of a 8 years old boy. For this purpose, a battery of seven HRP-conjugated lectins (SBA, DBA,PNA,WGA,UEAI, LTA and ConA) was used. D-galactose-N-acetyl-D-galactosamine and alpha-L-fucose sugar residues, which were present in the cytoplasm of the Sertoli cells of the normally positioned prepubertal testis, were not detected in the same cells of the undescended testis. The Leydig's cells of the descended testis appeared characterized by N-acetyl-D-glucosamine which was absent in the rare and atrophic Leydig's cells of the cryptorchid testis. Differences in sugar residues distribution between the descended and the undescended testis were also detected in the lamina propria of the seminiferous tubules. Peritubular myoid cells in the undescended testis only reacted with PNA, after neuraminidase digestion, thus revealing the presence of D-galactose (beta1-->3)-N-acetyl-D-galactosamine and sialic acid. In this study a complete distributional map of the sugar residues of the glycoconjugates in the descended and undescended prepubertal testis is reported.

Child↗
PubMedDate not supplied

Histochemical analysis of glycoconjugates in the eccrine glands of the raccoon digital pads.

The distribution and selectivity of complex carbohydrates in the eccrine glands of the digital pads in the North American raccoon (Procyon lotor) were studied using light and electron microscopic histochemical methods, particularly lectin histochemistry. In the eccrine glands, the dark cells exhibited neutral and acidic glycoconjugates with different saccharide residues (alpha-L-fucose, beta-D-galactose, beta-N-acetyl-D-glucosamine and N-acetyl-neuraminic acid); the clear cells contained numerous glycogen particles and showed a distinct reaction of alpha-L-fucose. The presence of complex carbohydrates with various terminal sugars was evident in the excretory duct cells. In addition, beta-D-galactose and N-acetyl-neuraminic acid residues were mainly observed in the luminal secretion. The glycoconjugates produced by the eccrine glands of the raccoon digital pads may protect the epidermis against physical damage or microbial contamination. In this way, the normal functioning of the sensory apparatus of the foot pads is ensured.

Animals↗
PubMed1991

[Distribution of glycoconjugates in gerbil hippocampal neurons--histochemical study with lectins].

Paraffin-embedded sections of gerbil hippocampus were made and stained by use of lectins with different sugar specificities: Concanavalin A (Con A), wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA), Phaseolus vulgaris agglutinin (PHA-E), peanut agglutinin (PNA), soybean agglutinin (SBA), and Vicia villosa agglutinin (VVA) to investigate the distribution of glycoconjugates in this brain region. Nuclear membranes of all the neurons in the hippocampus were positively stained with Con A and PHA-E, whereas WGA revealed definite staining of cell membranes. Endothelial cells of blood vessels were intensely positive to RCA, suggesting its usefulness as a marker of endothelial cells. With SBA and VVA, a few neurons in Ammon's horn were positively stained, while no positive cells were observed in the dentate gyrus. CA2 and the medial part of the CA1 were also positive bilaterally with SBA and VVA. Some neurons in Ammon's horn and dentate gyrus were selectively stained on the surface of their cell bodies with PNA. The present results show that lectins used distinguish different subpopulations of hippocampal neurons, indicating a new possible classification of hippocampal neurons based on their differences in glycoconjugates.

Animals↗
PubMed1990

[Study of the glycoconjugates in the mesonephros of the chick embryo using peroxidase-conjugated lectin].

The distribution of the sugar residues in glycoconjugates along the mesonephric nephron of chick embryo from the 4th day of incubation till hatching has been investigated, by means of six different horseradish peroxidase-labelled lectins. ConA and WGA showed an ubiquitous presence of alpha-D-mannose and N-acetyl-D-glucosamine along the nephrons. SBA was found to be a specific marker of the proximal tubule. PNA and LTA reacted only for a short time at some sites during the considered period of incubation. Sialic acid was detected at the glomerulus in the podocytes, capillary wall and, with a lesser extent, in the mesangial cells. Significant changes of the glycosylation pattern of the glycoconjugates during the period of mesonephric activity and the period of involution were seen.

Animals↗
PubMed1990

Occurrence of some blood group antigens-like glycoconjugates in colorectal tumors.

Expression of blood antigens A1, H, and T was studied in cells of benign and malignant tumors of colon and the rectum. The aim of the experiment was to verify the hypothesis on incomplete synthesis of glycoconjugates in the course of malignancy manifested also by an enhanced expression of H antigen compared to A antigen. A total of 152 patients with blood group A1 was examined by means of lectins DBA, UEA1, and PNA. The examination was complemented by the study of other glycosylative features and CEA expression. The results obtained do not support the mentioned hypothesis but suggest that reversal to malignancy can be associated with increased glycosylation or accumulation of abnormal glycoconjugates in the cells.

Adenoma↗
PubMed1990

Neuronal subsets express multiple high-molecular-weight cell-surface glycoconjugates defined by monoclonal antibodies Cat-301 and VC1.1.

Cat-301 and VC1.1 are monoclonal antibodies that recognize surface-associated molecules on subsets of mammalian CNS neurons. Earlier work demonstrated that Cat-301 recognizes a 680-kDa chondroitin sulfate proteoglycan (PG). VC1.1 has been shown to recognize 3 polypeptide bands on Western blot analysis; a major band at 95-105 kDa and additional bands at 145 kDa and 170 kDa. In the present report, we show that VC1.1 also reacts with a high-molecular-weight glycoconjugate. Immunoprecipitation experiments and biochemical characterizations indicate that Cat-301 and VC1.1 define at least 3 distinct high-molecular-weight antigens. The VC1.1 antigens react with antikeratan sulfate antibodies, while the Cat-301 antigens do not. By immunodepletion, we show that some VC1.1 antigens are Cat-301 positive, while others are Cat-301 negative. In addition, Cat-301-reactive proteoglycans are heterogeneous with respect to the presence or absence of VC1.1 epitopes. Double-label immunofluorescence studies with these 2 antibodies are consistent with the biochemical results and show that there are 3 classes of immunoreactive neurons in the cat CNS:Cat-301+/VC1.1+, Cat-301-/VC1.1+, and Cat-301+/VC1.1-. These results indicate that structural microheterogeneity exists among Cat-301 and VC1.1 high-molecular-weight glycoconjugates. This heterogeneity may be a reflection of the diverse neuronal phenotypes that are recognized by Cat-301 and VC1.1 in the mammalian CNS.

Animals↗
PubMed1990

Preliminary studies of serum glycoconjugates in patients with cancer using the enzyme-linked lectin assay.

After primary analyses on the serum glycoconjugates of lung cancer and normal individual using the enzyme-linked lectin assay (ELLA) with 12 kinds of lectins, PHA and LCA were selected for further study in the sera of 8 kinds of cancers, 4 kinds of non-malignant diseases and a kind of postoperative cancer. It was found that the test values of 7 kinds of cancers with PHA or LCA were significantly higher than those of the normal (P less than 0.01); the values of 4 kinds of non-malignant diseases with PHA were not higher (P greater than 0.05); the values of the postoperative cancer with PHA were obviously lower than those of the preoperative (P less than 0.02). The results showed that the serum glycoconjugates which can bind to PHA seemed related to the cancerous existence in human bodies. The significance of the findings was discussed.

Coronary Disease↗
PubMedDate not supplied

Glycoconjugate heterogeneity among five strains of Mycoplasma gallisepticum.

Five strains of Mycoplasma gallisepticum (MG) were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis for the presence of carbohydrate-containing components. Staining with periodic acid-Schiff (PAS) demonstrated carbohydrate components in three of the five strains studied. The PAS-reactive bands counterstained for protein, indicating a possible glycoprotein nature. Western blot analysis using three biotinylated lectin probes demonstrated the presence of additional glycoconjugates in the blot profiles of each MG strain. The carbohydrate specificity of lectin binding was demonstrated by competition experiments using specific sugars. Differences in the number, electrophoretic mobility and the morphology of PAS and lectin reactive bands were reproducible among separate preparations of each MG strain. These findings indicate substantial phenotypic diversity among the five MG strains in their ability to produce or acquire glycoconjugates.

Animals↗