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PubMed1997

Assessment of cell surface glycoconjugates in normal, benign and malignant human nasal mucosa.

Aberrant glycosylation of proteins is a common characteristic of neoplastic changes. No reports exist relating cell surface glycoconjugates to normal, benign and malignant human nasal mucosa. Using lectin affinity histochemistry, glycoconjugate reactivities for peanut agglutinin (PNA), concanavalin A (Con A), Griffonia simplicifolia agglutinin II (GSA-II), soy bean agglutinin (SBA) and Ulex europaeus agglutinin l (UEA-I) were analysed in the following groups: normal, benign (polyp, papilloma, and inverted papilloma) and malignant (squamous cell carcinoma (SCC) alone, SCC arising in inverted papilloma, and adenocarcinoma). The positive rate of lectin staining was evaluated using a quantitative AutoCAD programme. We correlated glycoconjugate expression to clinical features, diagnosis, and malignant transformation. The positive rate of PNA after neuraminidase pre-treatment (NA-PNA) staining was higher in inverted papilloma, while all-negative in polyp and papilloma. NA-PNA staining may be used as a differential diagnostic tool. Both inverted papilloma portions and SCC portions of the SCC synchronized with inverted papilloma subjects showed similar Con A and NA-PNA staining patterns. The biological characteristics define inverted papilloma as a pre-malignant neoplasm. The positive rate of PNA staining was significantly higher in inverted papilloma (inverted papilloma transformed to SCC) compared to inverted papilloma alone. Hence, PNA staining may predict malignant transformation of inverted papilloma. However, further investigations are required to prove this possibly worthwhile prognostic marker.

Adenocarcinoma↗
PubMed1998

[The effect of two beta-2 sympathomimetic bronchospasmolytics on the ratio of sialylated and sulfated glycoconjugates in goblet cell secretions of the tracheal epithelium].

Rabbits were made to inhale two different beta 2 sympathomimetic bronchospasmolytics-salbutamol in Ventolin and phenoterolhydrobromid in Berotec. Changes of secretion contents in tracheal goblet cells were evaluated by classical and lectin histochemistry 30 minutes after administration of drugs. When comparing with control rabbits Ventolin completely suppressed the secretion of neutral glycoconjugates for the benefit of acidic glycoconjugates and completely suppressed sialylation. The administration of Berotec suppressed neutral glycoconjugates, either, but the suppression of sialylation was uncomplete. Berotec was found a less damaging agent.

Albuterol↗
PubMed1999

Human milk glycoconjugates that inhibit pathogens.

Breast-fed infants have lower incidence of diarrhea, respiratory disease, and otitis media. The protection by human milk has long been attributed to the presence of secretory IgA. However, human milk contains large numbers and amounts of complex carbohydrates, including glycoproteins, glycolipids, glycosaminoglycans, mucins, and especially oligosaccharides. The oligosaccharides comprise the third most abundant solid constituent of human milk, and contain a myriad of structures. Complex carbohydrate moieties of glycoconjugates and oligosaccharides are synthesized by the many glycosyltransferases in the mammary gland; those with homology to cell surface glycoconjugate pathogen receptors may inhibit pathogen binding, thereby protecting the nursing infant. Several examples are reviewed: A fucosyloligosaccharide inhibits the diarrheagenic effect of stable toxin of Escherichia coli. A different fucosyloligosaccharide inhibits infection by Campylobacter jejuni. Binding of Streptococcus pneumoniae and of enteropathogenic E. coli to their respective receptors is inhibited by human milk oligosaccharides. The 46-kD glycoprotein, lactadherin, inhibits rotavirus binding and infectivity. Low levels of lactadherin in human milk are associated with a higher incidence of symptomatic rotavirus in breast-fed infants. A mannosylated glycopeptide inhibits binding by enterohemorrhagic E. coli. A glycosaminoglycan inhibits binding of gp120 to CD4, the first step in HIV infection. Human milk mucin inhibits binding by S-fimbriated E. coli. The ganglioside, GM1, reduces diarrhea production by cholera toxin and labile toxin of E. coli. The neutral glycosphingolipid, Gb3, binds to Shigatoxin. Thus, many complex carbohydrates of human milk may be novel antipathogenic agents, and the milk glycoconjugates and oligosaccharides may be a major source of protection for breastfeeding infants.

Anti-Infective Agents↗
PubMed1985

Glycoconjugate localization with lectin and PA-TCH-SP cytochemistry in rat hypophysis.

Glycoconjugates were localized by light microscopy with lectin-peroxidase conjugates and by electron microscopy with the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) sequence in immunocytochemically or morphologically identified cell types in rat pituitary. Lectin histochemistry demonstrated sialic acid and glycoconjugates with N-glycosidically linked oligosaccharides in gonadotrophs, thyrotrophs, and corticotrophs. Galactose penultimate to sialic acid was observed mostly in gonadotrophs. The terminal galactose-N-acetylgalactosamine disaccharide was detected in a few gonadotrophs and in a moderate number of mammotrophs. Fucose was localized in only corticotrophs with two fucose-binding lectins and in thyrotrophs with another. Several different monosaccharides were seen in glycoconjugates in melanotrophs and in Herring bodies. Melanotrophs displayed heterogeneous staining with fucose-binding lectins. A small number of nonsecretory cells were also visualized in the pars distalis by virtue of their glycogen content. PA-TCH-SP staining revealed complex carbohydrates in secretory granules and some Golgi cisternae in all types of hormone-producing cells in the pars distalis except for the somatotrophs. Melanotrophs of pars intermedia exhibited stained secretory granules and irregular dense bodies containing a stained meshwork. Corticotrophs of the pars distalis lacked the latter bodies, although they form the same glycoprotein precursor hormone as melanotrophs. Lectin conjugates and the PA-TCH-SP sequence stained some groups of secretion granules in Herring bodies, possibly representing vasopressin-containing granules as well as other cell types in the pars nervosa.

Animals↗
PubMed2004

Synthesis of tailor-made glycoconjugate mimetics of heparan sulfate that bind IFN-gamma in the nanomolar range.

We have recently described the preparation of three building blocks for the combinatorial synthesis of heparan sulfate (HS) fragments. Herein we show that one of these building blocks (disaccharide 4) allows the preparation, in high yields and with total alpha stereoselectivity, of tetra-, hexa- and octasaccharides from the heparin (HP) regular region, by using 2+2, 2+4 and 4+4 glycosylation strategies, respectively. These oligosaccharides were processed into sulfated derivatives bearing an allyl moiety in the anomeric position. The UV-promoted conjugation of these compounds with alpha,omega-bis(thio)poly(ethylene glycol) spacers of three different lengths allowed us to prepare nine benzylated glycoconjugates. After final deprotection, the glycoconjugates 1 a-c, 2 a-c and 3 a-c were obtained and their ability to inhibit the interaction between IFN-gamma and HP was tested by using surface plasmon resonance detection. Compound 3 b, containing two HP octasaccharides linked by a 50-A linker was able to inhibit the IFN-gamma/HP interaction with an IC(50) value of approximately 35 nM. In addition, the nine glycoconjugates were perfect tools in the study to ascertain the topology of the IFN-gamma binding site on HS. Compounds 1 a-c, 2 a-c and 3 a-c, by mimicking the alternating sulfated and nonsulfated regions found in HS, thus comprise the first example of a library of synthetic HS mimetics giving access to the "second level of molecular diversity" found in HS.

Amino Acid Sequence↗
PubMed2004

Lanthanide(III) complexes of DOTA-glycoconjugates: a potential new class of lectin-mediated medical imaging agents.

The synthesis and characterization of a new class of DOTA (1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane) monoamide-linked glycoconjugates (glucose, lactose and galactose) of different valencies (mono, di and tetra) and their Sm(III), Eu(III) and Gd(III) complexes are reported. The 1H NMR spectrum of Eu(III)-DOTALac2 shows the predominance of a single structural isomer of square antiprismatic geometry of the DOTA chelating moiety and fast rotation about the amide bond connected to the targeting glycodendrimer. The in vitro relaxivity of the Gd(III)-glycoconjugates was studied by 1H nuclear magnetic relaxation dispersion (NMRD), yielding parameters close to those reported for other DOTA monoamides. The known recognition of sugars by lectins makes these glycoconjugates good candidates for medical imaging agents (MRI and gamma scintigraphy).

Carbohydrates↗
PubMed1994

A chemically synthesized sialic acid-containing glycoconjugate, 2-(tetradecylhexadecyl)-O-(5-acetamido-3,5-dideoxy-D-glycero-alpha-D-ga lacto-2-nonulopyranosylonic acid)-(2-->3)-O-beta-D-galactopyrannosyl-(1-->4)-beta-D- glucopyrannoside, is a potent inhibitor of cellular immune responses.

Structural variations among gangliosides significantly influence their immunosuppressive activity. By total chemical synthesis, a sialic acid-containing glycoconjugate, 2-(tetradecylhexadecyl)-O-(5-acetamido-3,5-dideoxy-D-glycero-alpha -D-galacto-2-nonulopyranosylonic acid)-(2-->3)-O-beta-D-galactopyrannosyl-(1-->4)-beta-D- glucopyrannoside was synthesized. This glycoconjugate has the same carbohydrate structure as does GM3 ganglioside and a branched alkane in place of ceramide. It markedly inhibits the tetanus toxoid-induced human lymphoproliferative response in vitro (ID90 < 7 microM) and is five-fold more active than d18:1-C18:0 GM3 ganglioside, to which it is structurally related. This glycoconjugate is also a potent inhibitor of the murine alloimmune response in vivo: 10 nmol of the molecule injected subcutaneously together with an allogeneic cell challenge markedly inhibits the cellular immune response in the draining popliteal lymph node. In fact, the effect is quantitatively similar to that of systemically administered cyclosporin A, a well-studied immunosuppressive agent.

Animals↗
PubMed1995

Intermediate forms of glycoconjugates are present in the envelope of herpes simplex virions during their transport along the exocytic pathway.

In cells infected with herpes simplex virus 1, intracellular virions in transit along the exocytic pathway carry glycoconjugates that react, in fracture-label technique, with helix pomatia lectin. This lectin is specific for unsubstituted N-acetylgalactosamine, an intermediate sugar added in O-linkage to ser/thr residues in cis-Golgi and then substituted with galactose and sialic acid in the trans-Golgi. Virions in the perinuclear space do not react with helix pomatia lectin. In intracellular transport vesicles and vacules, close to the Golgi complex, virions are positively labeled by helix pomatia lectin and variably labeled by wheat germ agglutinin, a lectin specific for fully mature glycoconjugates. Extracellular virions react only with wheat germ agglutinin. The detection of glycoconjugates at intermediate steps of maturation, coupled with previous results that virions in the perinuclear space carry high mannose oligosaccharides (Torrisi et al., J. Virol. 66, 554-561, 1992), favor the view that maturation of herpes simplex virion envelope proceeds in a stepwise manner along the exocytic pathway. Should transit of virions involve a deenvelopment of enveloped virions followed by reenvelopment of naked nucleocapsids, our results rule out reenvelopment at trans- or post-Golgi compartments and could be consistent with reenvelopment occurring earlier in the exocytic pathway, most likely at the cis-Golgi.

Cell Line↗
PubMed1988

Altered lectin binding by colonic epithelial glycoconjugates in ulcerative colitis and Crohn's disease.

Evidence is accumulating that colonic mucin glycoconjugates are altered in ulcerative colitis. In order to investigate this further, the lectin-binding properties of rectal glycoconjugates have been studied in ulcerative colitis, Crohn's disease, and controls using lectin-peroxidase histochemistry. Ten lectins were used including peanut agglutinin (PNA) which is known to bind to malignant and adenomatous but not normal colonic mucins. Eight of 21 ulcerative colitis rectal biopsies and 10 of 17 Crohn's disease rectal biopsies showed PNA positivity, particularly in the supranuclear region of surface epithelial cells. There was no correlation between PNA positivity and duration of disease or inflammation, and none of the biopsies showed evidence of dysplasia. This abnormality in epithelial cell glycoconjugates seems to be commonly present in nondysplastic mucosa and occurs in both ulcerative colitis and Crohn's disease. It may reflect a fundamental abnormality in mucus glycoprotein synthesis in inflammatory bowel disease.

Adult↗
PubMed1986

GABAergic neurons of rodent brain correspond partially with those staining for glycoconjugate with terminal N-acetylgalactosamine.

Sections of fixed, paraffin-embedded brain from mice and rats were stained with agglutinin from Vicia villosa conjugated to horseradish peroxidase (VVA-HRP) to localize glycoconjugate containing terminal N-acetylgalactosamine (GalNAc). VVA-HRP binding sites were localized in periodic foci at the surface of a selective population of non-pyramidal interneurons in layers II through IV of the rodent cerebral cortex. These multipolar interneurons were shown to utilize gamma-aminobutyric acid (GABA) as a transmitter and thus to be GABAergic by their immunostaining for glutamic acid decarboxylase (GAD) throughout the cytoplasm in serial sections. Pyramidal and other non-pyramidal cortical neurons received GABAergic input as evidenced by punctate immunostaining for GAD on their soma and proximal dendritic arborizations, but these cells failed to show VVA affinity or cytosolic GAD reactivity. Most neurons in the thalamic reticular nucleus stained for the presence of glycoconjugate with terminal GalNAc on their surface and for GAD in the cytosol. In contrast, cerebellar Purkinje cells showed strong cytosolic reactivity with anti-GAD but lacked surface staining with VVA-HRP. These observations show that some but not other populations of GABAergic neurons possess binding capacity for VVA on their surface. The surface of neurons in the deep cerebellar nucleus stained heavily with VVA but failed to show clear cytosolic reactivity for GAD. Some neurons with surface glycoconjugate containing terminal GalNAc are therefore not GABAergic.

Acetylgalactosamine↗
PubMed1986

The cytochemistry of glycoconjugates in the zona pellucida of murine ovarian oocytes and two-cell embryos.

Changes in glycoconjugates of the zona pellucida induced by maturation, ovulation and fertilization of mouse oocytes have been studied by means of light microscopic methods of cytochemistry. These methods consisted of periodic acid-Schiff (PAS), Alcian Blue pH 1.0 and pH 2.5, and peroxidase-labelled lectin diaminobenzidine (PO-LT-DAB) procedures in combination with the digestion technique with neuraminidase. According to the results obtained, glycoconjugates of the zona pellucida of fertilized eggs contained a smaller amount of sulphate groupings than that in ovarian oocytes, whereas their reactions for sialic acid and fucose residues were significantly stronger in intensity in the former, as compared with those in the latter. The cytophysiological significance of such cytochemical changes in glycoconjugates of the zona pellucida has been discussed with special reference to its functional alterations following maturation, ovulation and fertilization.

Animals↗
PubMedDate not supplied

Glycoconjugates in the secretory epithelium of the chicken mandibular gland.

In the secretory epithelium of the chicken mandibular gland, glycoconjugates have been studied by means of histochemical methods of light and electron microscopy. In light microscopy, a series of histochemical procedures have been employed which included lectin--peroxidase--diaminobenzidine methods and a digestion technique with neuraminidase or alpha-amylase. In electron microscopy, a battery of methods were used that corresponded to those employed in light microscopy. In the secretory cells of the chicken mandibular gland, vicinal diol- and sulphate-containing glycoconjugates with sialic acid, alpha-D-mannose, alpha-D-glucose and beta-D-galactose residues were visualized and the possible histophysiological significances of such glycoconjugates were discussed with special reference to the functions of the salivary gland.

Animals↗
PubMed1983

Cytochemical localization of small intestinal glycoconjugates by lectin histochemistry in controls and subjects with cystic fibrosis.

Human mucosal glycoconjugates were examined in normal small intestinal biopsies from five control subjects using six different fluorescein-conjugated lectins: Triticum vulgare agglutinin (WGA), Ulex europaeus agglutinin I (UEA1), Ricinus communis agglutinin I (RCA1), glycin max-soy bean agglutinin (SBA), Dolichus biflorus agglutinin (DBA), and Arachis hypogaea peanut agglutinin (PNA). These plant agglutinins bind to specific nonreducing end-terminal carbohydrate residues. Only the lectins derived from WGA, which produced the strongest staining, and UEA1 consistently bound to both intestinal goblet cell mucin and epithelial cell microvillar membranes. The intensity of lectin binding was greatest in the upper villus and diminished down towards the crypt, being weakest in the crypt base. Similar histochemical studies carried out on small bowel biopsies from five patients with cystic fibrosis revealed no major qualitative differences between the intestinal glycoconjugates in normal subjects and those with cystic fibrosis. These results suggest that glycoconjugate biosynthesis of human intestinal goblet cell mucin and epithelial cell membranes may be complete and hence full differentiation achieved only when these cells have migrated out of the crypt and onto the villus.

Biopsy↗
PubMed1986

Evidence for glycoconjugate in nociceptive primary sensory neurons and its origin from the Golgi complex.

Glycoconjugates with terminal galactose residues were localized in rat spinal cord and spinal ganglia using lectin-HRP conjugates of Griffonia simplicifolia and Glycine max agglutinins. Alternate staining of serial sections with HRP-labelled lectins and an antibody for substance P (SP) showed staining in identical primary sensory neurons with both methods. Similarly, lectin-reactive as well as SP-positive fibers were found in Rexed laminae I and II, Lissauer's tract, the spinal nucleus and tract of the trigeminal nerve, the nucleus commissuralis and a small bundle of fibers just ventral to the central canal. Administration of capsaicin to neonatal rats produced a significant decrease in lectin-reactive fibers of the substantia gelatinosa, and in the number of lectin-reactive sensory neurons. The coexistence of SP with galactose-containing glycoconjugates in spinal ganglion neurons, as well as sensitivity of these cells to capsaicin, provided a basis for classifying the reactive neurons as nociceptive in type. Ligation of dorsal roots resulted in disappearance of lectin reactivity in the spinal cord and caused accumulation of lectin-positive material proximal to the ligature, indicating somatofugal transport of galactose-containing glycoconjugates. Colchicine injection caused an increase in SP reactivity in dorsal ganglion neurons but no change in lectin staining of galactoconjugate. At the ultrastructural level affinity for the lectin conjugates was confined to the Golgi cisternae and the plasmalemma of B-type sensory neurons in the dorsal ganglion. The axolemma of unmyelinated processes stained selectively in dorsal roots and the substantia gelatinosa of the spinal cord. These findings provide evidence for the presence in certain sensory cells of a characteristic galactosylconjugate which may prove to be of significance in nerve function.

Animals↗
PubMed1987

Glycoconjugates in the colons of New World monkeys with spontaneous colitis. Association between inflammation and neoplasia.

A spontaneously occurring experimental model of chronic colitis has been described in three closely related species of New World monkeys. One species, Saguinus oedipus oedipus, has the additional feature of developing adenocarcinoma of the colon in this setting. Pathological and lectin histochemistry studies were undertaken in 50 such colonic specimens to determine if pathological or histochemical features were associated with the concomitant development of cancer. Chronic inflammation was found in all of the colons examined, and 14% had features of acute inflammation, which was significantly associated with those animals that developed cancer. An oncofetal glycoconjugate structure has been defined in human colons by the ability to bind peanut lectin. A similar glycoconjugate, probably a mucin, was expressed in the colons of 65% of these animals. A marked degree of expression of the mucin was significantly associated with those animals that developed cancer. A highly significant association was found between the presence of acute inflammation and the expression of the mucin. These studies demonstrate similarities in glycoconjugate expression between the human colon and the New World monkey model of spontaneous colitis. A form of mucin is expressed in these animals that is highly associated with both the presence of acute inflammation and the development of cancer elsewhere in the colon. In addition, an association between acute inflammatory activity and neoplasia was found, suggesting a potential etiologic linkage between the two.

Animals↗
PubMed1988

Alterations in mucosal content of colonic glycoconjugates in inflammatory bowel disease defined by monoclonal antibodies.

The presence of several glycoconjugates in colonic mucosa of patients with inflammatory bowel disease was assessed through indirect immunofluorescent staining using a collection of 23 monoclonal antibodies directed against human colonic mucin glycoproteins (anti-HCM MAbs). Intensity and distribution of staining by three anti-HCM MAbs were significantly altered in mucosa from patients with ulcerative colitis (UC) (n = 14) when compared with normal tissue (n = 15) and with tissue from patients with Crohn's disease as well as other inflammatory disorders (n = 15). Staining by anti-HCM MAb 17, which binds to colonic mucin glycoprotein species IV and V, was absent or diminished in 86% of samples from patients with active UC in contrast to 14% of normal and disease control specimens. Reduction in anti-HCM MAb 17 staining was less marked in mucosal biopsy specimens from patients with UC lacking acute inflammatory activity (n = 8). In contrast to the apparent loss of the MAb 17-defined epitopes, staining with anti-HCM MAbs 10 and 22 was enhanced in UC tissue compared with normal and disease controls. Increased staining with MAb 10 was present in 93% of samples from UC patients demonstrating active inflammation. Increased MAb 10 staining was not apparent in noninvolved mucosa from UC patients, indicating that increased expression of the specified epitope is related to the acute inflammatory process. In contrast, indirect immunofluorescent staining with MAb 22 was apparent in both involved (78%) and uninvolved (67%) UC mucosa in contrast to normal and disease controls (less than 12%). In addition, staining with several other anti-HCM MAbs (MAbs 3, 11, 15) was modestly and variably diminished (14%-28%) in UC, Crohn's disease, and other inflammatory disorders. These findings demonstrate the presence of alterations in mucosal content of specific glycoconjugate structures in association with UC. Inflammatory processes may also result in broad changes in glycoconjugate determinants generally.

Antibodies, Monoclonal↗
PubMed2005

Lycium barbarum glycoconjugates: effect on human skin and cultured dermal fibroblasts.

Lycium barbarum L. (Solanaceae) glycoconjugates (LbGp) display an interesting array of anti-apoptotic and antioxidant properties, which may be beneficial for human skin. We therefore set out to determine the effects of LbGp in full-thickness human skin, and in dermal fibroblasts. It was found that LbGp decreased the level of MMP (matrix metalloproteinase)-1 significantly, but not that of MMP-3 or -13, in the whole human skin system, without compromising the viability of the skin. Consistently, LbGp inhibited skin expansion under mechanical stress, which in this model depends on the activity of MMP-1. We found that one of L. barbarum glycoconjugates, the LbGp5, promoted the survival of human fibroblasts cultured in suboptimal conditions. Furthermore, in the presence of LbGp5, these cultures also contained higher levels of the MMP-1 substrate--collagen type I. Together these results suggest that L. barbarum glycoconjugates in general, and LbGp5 in particular, may have important skin-protective properties.

Antioxidants↗
PubMed2001

Glycoconjugate stability in human milk: glycosidase activities and sugar release.

Many human milk glycoconjugates (glycolipids, glycoproteins, mucins, glycosaminoglycans) and oligosaccharides are biologically active, and their activity depends on the precise structure of the glycan. The sugars on the terminus of the glycan are vulnerable to cleavage by glycosidases. Because glycoconjugates incubate together with endogenous glycosidases in the breast between feedings, and in expressed milk during storage, the presence and activity of glycosidases in human milk was investigated. alpha-L-Fucosidase, alpha-D-galactosidase, beta-D-galactosidase, beta-D-glucosidase, N-acetyl-beta-hexosaminidase, beta-D-glucuronidase, and neuraminidase were measured in milk samples from 4 donors by use of synthetic fluorogenic glycosides; fucosidase and hexosaminidase displayed the highest activity. The catabolic activity of the major glycosidases was confirmed by measuring the corresponding free sugars in milk. Free fucose, N-acetylneuraminic acid, and N-acetylhexosamines were measured and their identities were confirmed by high-performance liquid chromatography, gas chromatography, and gas chromatography-mass spectrometry. Incubation of samples for 16 hr at 37 degrees C and 20 degrees C, but not at 4 degrees C, resulted in time-dependent increases in the amount of free fucose, N-acetylneuraminic acid, and N-acetylhexosamines, consistent with their enzymatic release by the endogenous glycosidases. Stored frozen milk had the same levels of these sugars as did samples analyzed immediately after collection, indicating that glycosidases are inactive in the frozen milk. Samples analyzed immediately after collection contained only small amounts of free sugars, suggesting that glycoconjugate degradation during the typical residence time of milk in the breast is modest.

Journal Article↗