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PubMedDate not supplied

Brain gangliosides: increased incorporation of (1- 3H) glucosamine during training.

The incorporation of (1-3H)glucosamine into biochemical fractions of brain was studied in mice trained in a conditioned avoidance jump-up task, in mice yoked to the trained animals, and in undisturbed mice in their home cages. The (3H)glucosamine was injected subcutaneously 15 min before 15 min of training, and the mice killed after a total pulse time of one hour. There was a consistent and significant increase of about 21 percent of the incorporation of the 3H into the brain ganglioside fraction when trained mice were compared with quiet mice. This increase was not observed in any of the other chemical fractions studied, including the total chloroform-methanol-soluble compounds, the non-ganglioside lipids, and the chloroform-methanol-insoluble compounds (radioactivity principally in glycoprotein). Yoked mice showed an intermediate level of incorporation, exhibiting only a 12 percent increase in the ganglioside fraction. When the individual ganglioside species were analyzed by thin-layer chromatography the changed incorporation was not specific for any ganglioside species.

Animals↗

PubMed1978

Glucosamine incorporation into rat cerebrum: effect of adrenalectomy, corticosterone, exercise, and training.

Incorporation of D-[I-14C]glucosamine into various metabolic fractions was studied in an experiment designed to quantify the relative influence of physiological and behavioral factors. Different physiological states were established by sham operation (S), adrenalectomy (A), and adrenalectomy plus corticosterone replacement (H). Within each physiological condition the behavioral state was varied by swim-escape training (E), swimming exercise (X) or nonswimming controls (C). Adrenalectomy caused a generalized increase in label uptake by cerebral cortex and hippocampus, but precursor levels in the blood were elevated also, suggesting a systemic physiological effect. Behavioral state had no effect on overall uptake, but did influence the distribution of label between soluble and membrane-bound glycoproteins. These results indicate that D-[I-14C]glucosamine is an effective glycoprotein and ganglioside precursor in behavioral experiments, provided corrections for the influence of systemic physiological factors are made.

Adrenalectomy↗

PubMed1975

Glucosamine-labelled envelope proteins of Escherichia coli K-12. II. Location in inner and outer membranes.

Outer and inner membranes were prepared from a culture of a glucosamine- and leucine-requiring mutant of Escherichia coli K-12, which was grown on L-[4,5-(3)H2]leucine and D-[1-(14)C]glucosamine and "chased" with unlabelled medium. Phenol-soluble glycoproteins were obtained from these membranes after phospholipid extraction. Sodium dodecyl sulfate-disc electrophoresis of the outer-membrane glycoproteins separated two components which were labelled with both isotopes and had a fast (F) and intermediate (I) migration. Dodecyl sulfate electrophoresis of the inner-membrane glycoproteins showed that only the F band incorporated both 14C and 3H labels. The 3H to 14C ratio in the F band from the outer membrane was completely different from the isotopic ratio in the F band from the inner membrane, indicating that these components were not identical despite their similar molecular weights. The F bands from both membranes lost their label during the chase with unlabelled medium, while the I band remained relatively stable. Chloroform-soluble 14C label extracted from the outer membrane decreased during the chase. In contrast, the chloroform-soluble 14C from the inner membrane, accumulated during the chase.

Bacterial Proteins↗

PubMed1978

Glucosamine metabolism in Drosophila salivary glands. Separation of metabolites and some characteristics of three enzymes involved.

The conversion of fructose 6-phosphate to mucopolysaccharide precursors was studied in extracts of Drosophila virilis salivary glands. 1. Methods for chromatography of sugar phosphates were adapted and modified to allow routine separation and quantitation of radioactivity of the metabolites from milligram amounts of tissue. Anion exchange chromatography was performed on Dowex 1-X8 employing steps of increasing ammonium formate. Final isolation of each compound was achieved by various thin-layer chromatographic systems. 2. Data obtained by isotope incorporation into glucosamine 6-phosphate compare well with results of the Morgan-Elson colorimetric assay for amino-sugars. 3. Glucosaminephosphate isomerase (glutamine-forming) (EC 5.3.1.19) in gland extracts has a Km of 0.35 mM for fructose 6-phosphate, and of 0.25 mM for glutamine. The enzyme is inhibited at glutamine concentrations exceeding 1 mM and by UDP-N-acetylglucosamine (50% at 0.6 mM). Feedback inhibition by UDP-N-acetylglucosamine is enhanced by AMP and by glucose 6-phosphate. 4. Glucosaminephosphate isomerase (EC 5.3.1.10) has a twenty fold lower affinity towards fructose 6-phosphate (Km = 6.0 mM) compared to the glutamine-forming isomerase. Km (NH+4) is 7.4 mM. In the presence of 20 mM glucose 6-phosphate, the pH optimum is shifted from 6.6 to 7.4, and V increased by a factor of 2.5. Furthermore, the affinity is approximately doubled for both substrates. 5. Glucosamine acetyltransferase (EC 2.3.1.3) has a Km of 2 mM for glucoseamine 6-phosphate. Its activity is not rate-limiting in salivary glands. Since N-acetylglucosamine 6-phosphate and 1-phosphate were found near equilibrium concentrations, acetylglucosamine phosphomutase (EC 2.7.5.2) must also be present in the extracts.

Acetyltransferases↗

PubMed1979

Regulation of glucosamine-6-phosphate deaminase synthesis in yeast.

A basal level of glucosamine-6-phosphate deaminase is detected in yeast cells grown on glucose. However, a burst of enzyme production occurs in the presence of N-acetylglucosamine in pathogenic Candida albicans and non-pathogenic Saccharomyces cervisiae. The enzyme synthesis stops and its concentration in the cells declines rapidly as soon as N-acetylglucosamine is removed from the medium. Experiments with RNA- and protein-synthesis inhibitors indicate that the appearance of new enzyme activity is dependent on concomitant new protein synthesis and the inducer operates at a transcriptional level. However, inhibition of DNA synthesis either by hydroxyurea or by mitomycin-C does not impair the synthesis of glucosamine-6-phosphate deaminase.

Acetylglucosamine↗

PubMed1988

Synthesis and secretion of mucous glycoprotein by the gill of Mytilus edulis. I. Histochemical and chromatographic analysis of [14C]glucosamine bioincorporation.

The ability of the isolated gill epithelium of Mytilus edulis to incorporate [14C]glucosamine as a precursor in the biosynthesis and secretion of mucous glycoproteins was investigated. Localization of mucous cells in the gill filament was achieved using histochemical staining techniques. Mucus cells containing neutral and acidic mucins were found in the lateral region, whereas mucus cells containing primarily neutral or sulfated mucins were found in the abfrontal region. Autoradiographic results showed that in both regions, the mucous cells were rich in content of the incorporated radiolabel. The secreted glycoproteins containing the incorporated radiolabel were analyzed by column chromatography using Bio-Gel P-2 and P-6. Two populations of the glycoproteins differing in molecular size were isolated. Upon alkaline reductive borohydride cleavage of the O-glycosidic linkages of the high molecular weight protein, about 70% of the radiolabel and 85% of the carbohydrate content were removed from the protein. The alkaline borohydride cleavage resulted in the formation of at least six oligosaccharide chains of various lengths of sugar units. Gas chromatographic analysis of the carbohydrate composition shows that the glycoproteins contain N-acetylglucosamine, N-acetylgalactosamine, and galactose, fucose, and mannose as the neutral monosaccharides. The above results indicate that the isolated gill epithelium of M. edulis is capable of incorporating [14C]glucosamine in the synthesis of secretable mucin-type glycoproteins.

Animals↗

PubMed1994

The neglect of glucosamine as a treatment for osteoarthritis--a personal perspective.

Osteoarthritis results from progressive catabolic loss of cartilage proteoglycans, owing to an imbalance between synthesis and degradation. Standard drug therapy is only of palliative benefit and may exacerbate loss of cartilage. Glucosamine is an intermediate in mucopolysaccharide synthesis, and its availability in cartilage tissue culture can be rate-limiting for proteoglycan production. A number of double-blind studies dating from the early 1980s demonstrate that oral glucosamine decreases pain and improves mobility in osteoarthritis, without side effects. Nevertheless, medical researchers and physicians in the US have totally ignored this rational and safe therapeutic strategy. By mechanisms that are still unclear, the natural methyl donor S-adenosylmethionine also promotes production of cartilage proteoglycans, and is therapeutically beneficial in osteoarthritis in well-tolerated oral doses. These and other safe nutritional measures supporting proteoglycan synthesis, may offer a practical means of preventing or postponing the onset of osteoarthritis in older people or athletes.

Animals↗

PubMed1993

Incorporation of D3H glucosamine to the adult and developing cochlear tectorial membrane of normal and hypothyroid rats.

The uptake of D-3H-glucosamine by the developing cochlea of normal and hypothyroid rats was examined using light microscopic radioautography. During postnatal development, normal and hypothyroid rat cochleas exhibited a layer of radiolabelling in the tectorial membrane (TM). This layer first appeared in the TM region which covers the spiral limbus and the Kölliker's organ (KO), then progressively reached the apical part of the TM covering the organ of Corti. Radiolabelling was significantly greater in hypothyroid than in normal cochleas. These findings suggests that the enormous size reached by the TM in the congenital hypothyroidism could be related to an increase of epithelial secretion, at least for carbohydrates. It also suggests that TM, in normal and hypothyroid cochleas, could be formed during development by the addition of successive layers. Older layers could be displaced upwards by the new ones. Cochleas of normal young adult rats, treated with D-3H-glucosamine, showed a very scarce and diffuse radiolabelling. Cochleas of hypothyroid young adult rats exhibited a thickened and distorted TM, which incorporated a significant amount of carbohydrates. These results suggest that TM secretion is highly reduced in young adult normal animals, while in young adult hypothyroid ones it is still active. During cochlear maturation, thyroxine seems to be necessary, not only for the synthesis of normal glycoproteins (as suggested by previous reports), but also for the control of glycoprotein secretion.

Animals↗

PubMed2005

N-Acyl derivatives of glucosamine as acceptor substrates for galactosyltransferase from bone and cartilage cells.

Glucosamine is commonly used as a nutraceutical by arthritis patients. However, its mode of action is still unknown, and there is controversy about its clinical efficacy. Synthetic N-acyl glucosamines (acyl group>2 carbons) comprise a new class of drugs. We examined these derivatives for their effect in bone and cartilage cells, and for their ability to serve as acceptor substrates for galactosyltransferase. With the exception of N-benzoylglucosamine, compounds of the series were good substrates for galactosyltransferases from bone and cartilage cells, and for purified enzyme from bovine milk. When N-butyrylglucosamine (GlcNBu) was added to the cell medium of primary bovine chondrocytes and human osteoblasts, small amounts were found to enter the cells and a radiolabeled metabolite appeared in the medium. However, GlcNBu did not appear to be incorporated directly into oligosaccharides. GlcNBu at 1 and 5mM concentrations in the glucose-free cell medium of primary human osteoblasts from osteoarthritis patients did not significantly alter cell proliferation or cell differentiation.

Animals↗

PubMed2006

Synthesis of beta-(1-->6)-linked glucosamine oligosaccharides corresponding to fragments of the bacterial surface polysaccharide poly-N-acetylglucosamine.

A series of 3-beta-acetamidopropyl oligo-beta-(1-->6)-glucosamines consisting of 5, 7, 9 and 11 glucosamine residues, and a series of corresponding per-N-acetylated derivatives were synthesized using a convergent blockwise approach. These compounds represent fragments of a bacterial surface polysaccharide produced by numerous bacterial pathogens, including Staphylococcus aureus, and will be used as models for its biochemical and immunological properties.

Acetylglucosamine↗

PubMed2006

Rapid on-column analysis of glucosamine and its mutarotation by microchip capillary electrophoresis.

A novel electrophoretic microchip method for analyzing alpha- and beta-d-glucosamine and their interconversion in solution is presented. d-Glucosamine is labeled with fluorescamine and analyzed by capillary electrophoresis in under 2 min revealing its pH-dependent mutarotation between the alpha- and beta-anomers. The forward interconversion rates for the labeled sugars, based on an iterative analysis of the plateau heights between the peaks, are 0.72+/-0.09, 1.3+/-0.1, and 2.2+/-0.3 x 10(-3)s(-1) at pH 8.99, 9.51 and 10.01, respectively. In a separate experiment, the mutarotation of the unlabeled alpha-d-anomer was followed; the relative intensities of the alpha- and beta-peaks as a function of reaction time at pH 9.51 give a forward rate constant of 0.6+/-0.1 x 10(-3)s(-1). These results demonstrate that fast microchip separations, previously exploited for amine, amino acid, and nucleobase analysis, can also be used to analyze amino sugars and their mutarotation.

Electrophoresis, Microchip↗

PubMed2006

Glucosamine sulfate inhibits leukocyte adhesion in response to cytokine stimulation of retinal pigment epithelial cells in vitro.

Glucosamine is an amine-containing sugar that exhibits immunosuppressive effects in vitro and in vivo, although its mechanism of action is unknown. We investigated whether glucosamine sulfate (GS) modulates the proinflammatory cytokine interleukin (IL)-1beta-induced expression and production of intercellular adhesion molecule (ICAM)-1, the mechanism responsible for this effect, and whether GS inhibits leukocyte adhesion to the monolayer of retinal pigment epithelial (RPE) cells stimulated with various cytokines. We used flow cytometry and an ARPE-19 cell model to determine the effect of GS on the production of ICAM-1 in response to IL-1beta, IL-6, tumor necrosis factor (TNF)-alpha plus IL-1beta, TNF-alpha plus IL-6, and TNF-alpha plus interferon (IFN)-gamma. We also used semiquantitative RT-PCR to determine the effect of GS on IL-1beta-induced expression of the ICAM-1 gene, and immunocytochemistry and western blotting to measure the effect of GS on the activation and nuclear translocation of the nuclear factor NF-kappaB and the degradation of cytoplasmic IkappaB. The functionality of GS-modulated ICAM-1 on leukocyte adhesion was demonstrated in an RPE cell-neutrophil adherence assay. IL-1beta increased the expression of ICAM-1 at the mRNA and protein levels in ARPE-19 cells. GS downregulated the production of ICAM-1 induced by IL-1beta, IL-6, TNF-alpha, and IFN-gamma at the protein level in a dose-dependent manner. GS also inhibited the nuclear translocation of NF-kappaB subunit p65 and partially prevented the degradation of cytoplasmic IkappaB in IL-1beta-stimulated ARPE-19 cells. GS significantly decreased the number of neutrophils adhering to the RPE monolayer in response to cytokines IL-1beta, IL-6, TNF-alpha, and IFN-gamma. GS inhibits the expression of the ICAM-1 gene in ARPE-19 cells stimulated with IL-1beta by blocking NF-kappaB subunit p65 translocation and by partially preventing IkappaB degradation. GS also decreases leukocyte adhesion to the monolayer of ARPE-19 cells stimulated with various cytokines by decreasing ICAM-1 production. Our study demonstrates a potentially important property of GS in reducing ICAM-1-mediated inflammatory mechanisms in the eye.

Cell Adhesion↗

PubMed2006

Risk assessment for glucosamine and chondroitin sulfate.

Glucosamine and chondroitin sulfate are two popular dietary ingredients present in dietary supplements intended to support joint health. A large body of human and animal research suggests that oral intakes of these ingredients, either alone or in combination, reduces joint pain and improves mobility in persons with osteoarthritis. The increased awareness and use of these ingredients in dietary supplements warrant a comprehensive review of their safety. Systematic evaluation of the research designs and data do not provide a basis for risk assessment and the usual safe upper level of intake (UL) derived from it unless the newer methods described as the observed safe level (OSL) or highest observed intake (HOI) are utilized. The OSL risk assessment method indicates that the evidence strongly supports safety at intakes up to 2000 mg/d for glucosamine, and 1200 mg/d for chondroitin sulfate, and these levels are identified as the respective OSL. These values represent the highest levels tested in human clinical trials. The complete absence of adverse effects at these levels supports a confident conclusion of their long-term safety.

Administration, Oral↗

PubMed2001

Generation of anti-factor Xa active, 3-O-sulfated glucosamine-rich sequences by controlled desulfation of oversulfated heparins.

In the framework of a project aimed at generating heparin-like sulfation patterns and biological activities in biotechnological glycosaminoglycans, different approaches have been considered for simulating the alpha(1-->4)-linked 2-O-sulfated L-iduronic acid (IdoA2SO(3))-->N,6-O-sulfated D-glucosamine (GlcNSO(3)6SO(3)) disaccharide sequences prevalent in mammalian heparins. Since the direct approach of sulfating totally O-desulfated heparins, taken as model compounds for C-5-epimerized sulfaminoheparosan (N-deacetylated, N-sulfated Escherichia coli K5 polysaccharide), preferentially afforded heparins O-sulfated at C-3 instead than at C-2 of the iduronate residues, leading to products with low anticoagulant activities, the problem of re-generating a substantial proportion of the original IdoA2SO(3) residues was circumvented by performing controlled solvolytic desulfation (with 9:1 v/v DMSO-MeOH) of extensively sulfated heparins. The order of desulfation of major residues of heparin GlcN and IdoA and of the minor one D-glucuronic acid was: GlcNSO(3)>GlcN6SO(3)>IdoA3SO(3) congruent with GlcA2SO(3) congruent with GlcN3SO(3)>IdoA2SO(3) congruent with GlcA3SO(3). Starting from a 'supersulfated' low-molecular weight heparin, we obtained products with up to 40% of iduronate residues O-sulfated exclusively at C-2 and up to 40% of their glucosamine residues O-sulfated at both C-6 and C-3. Upon re-N-sulfation, these products displayed an in vitro antithrombotic activity (expressed as anti-factor Xa units) comparable with those of current low-molecular weight heparins.

Animals↗

PubMed2003

A practical synthesis of a (1-->6)-linked beta-D-glucosamine nonasaccharide.

A (1-->6)-beta-D-glucosamine nonasaccharide was convergently synthesized using isopropyl thioglycosides as donors. Anomeric acetylated glucosamine derivatives were proved to be good acceptors in the NIS/TMSOTf catalyzed glycosylation. The target nonasaccharide showed a mild antitumor activity against H22 on the preliminary mice tests.

Animals↗

PubMed1982

Clonal analysis of a human lymphoblastoid cell line (B17) secreting antibody to N-acetyl-D-glucosamine.

In this paper we analyse the clonal composition of a human lymphoblastoid B-cell line secreting IgM/k antibody to N-acetyl-D-glucosamine, the immunodominant sugar of Group-A-streptococcal carbohydrate. Besides non-antibody secreting cells, the line consists of two clonotypes of antibody-secreting cells: B17 cells producing over 90% and F6 cells producing less than 10% of the antibody in the supernatant. The proportions of B17 and F6 cells in the cell line seem to be similar to the proportion of antibodies in the supernatant. F6 cells can be isolated by cloning and maintained as stable lines, whereas this is more difficult with B17 cells. The results suggest that upon establishment of the line, at least two N-acetyl-D-glucosamine-specific B cells were immortalized and coexist together as independent clonotypes. Although F6 cells seem to have a slight tissue culture advantage, they represent the minor clonotype in the B17 cell line.

Acetylglucosamine↗

PubMedDate not supplied

Purification of an N-acetyl-D-glucosamine specific lectin (P.B.A.) from epidermal cell membranes of Pieris brassicae L.

We report the isolation and the purification of an N-acetyl-D-glucosamine specific lectin capable of agglutinating either fixed trypsinized rabbit erythrocytes or chitin particles. An agglutinin assay based on the affinity of this lectin for the chitin was devised with fluorescent particles of scorpion cuticle to measure lectin activity during purification steps. Lectin was isolated from epidermal cell membranes; its molecular weight was determined by gel filtration and polyacrylamide electrophoresis in sodium dodecyl sulfate. Mr was estimated to be 43,000. Lectin could be constituted by two subunits. Mr of which was estimated to be 23,000. The specificity of this lectin against N-acetyl-D-glucosamine and its oligomers suggests a possible role in the dynamics of these saccharides during the cuticle cycle.

Acetylglucosamine↗

PubMed1996

Glucosamine for wound healing.

The rapid production of hyaluronic acid by fibroblasts in the early stages of wound healing may be of crucial importance as hyaluronic acid stimulates the migration and mitosis of mesenchymal and epithelial cells. Increased levels of hyaluronic acid, as observed during fetal wound healing or as achieved by the topical application of hyaluronic acid during wound dressing, are associated with brisker healing and reduced scarring. Glucosamine availability appears to be rate-limiting for hyaluronic acid synthesis. Thus the administration of adequate amounts of glucosamine by mouth during the first few days after surgery or trauma can be expected to enhance hyaluronic acid production in the wound, promoting swifter healing and possibly diminishing complications related to scarring.

Administration, Oral↗