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PubMed1965

REOVIRUS HEMAGGLUTINATION: INHIBITION BY N-ACETYL-D-GLUCOSAMINE.

Purified reoviruses types 1, 2, and 3 were specifically inhibited in their hemagglutination of human erythrocytes by 250 micromoles or more of N-acetyl-D-glucosamine but not by over 20 other sugars tested. N-acetyl-D-glucosamine inhibited reovirus hemaglutination by binding to capsid virus; it did not attach to the erythrocytes. It is possible that reovirus hemagglutination involves union between N-acetyl-D-glucosamine on the surface of the red cell and the glycoprotein of the virus coat.

Acetylglucosamine↗

PubMed1979

Wheat germ agglutinin blockage of chlamydial attachment sites: antagonism by N-acetyl-D-glucosamine.

Addition of 2 to 10 micrograms of wheat germ agglutinin (WGA), a lectin from Triticum vulgaris specific for N-acetyl-D-glucosamine, per ml to suspensions of mouse fibroblasts (L cells) blocked the attachment of 14C-labeled Chlamydia psittaci 6BC to the L-cell surface. WGA and strain 6BC competed for similar sites on L cells, but once bound, one was not replaced by the other. N-Acetyl-D-glucosamine, but not other monosaccharides of related structure, antagonized the blocking action of WGA. Lectins with specificities other than that of WGA prevented chlamydial attachment only at much higher concentrations or not at all. Exposure of L cells to trypsin and to high multiplicities of strain 6BC decreased the amount of subsequently added 3H-labeled WGA that was bound by these cells. WGA also blocked the attachment of strain 6BC to other established cell lines of murine, simian, and human origin. A lymphogranuloma venereum strain (440L) of C. trachomatis was just as sensitive to the blocking action of WGA as was strain 6BC. It appears that the attachment of both C. psittaci and C. trachomatis to host cells of diverse origin involves an N-acetyl-D-glucosamine-containing entity that binds WGA with high affinity.

Acetylglucosamine↗

PubMed1975

Sporulation in D-glucosamine auxotrophs of Saccharomyces cerevisiae: meiosis with defective ascospore wall formation.

Mutants that require exogenous D-glucosamine for growth were isolated from Saccharomyces cerevisiae X2180-1A after ethyl methane sulfonate mutagenesis. Class A auxotrophs fail to grow on yeast extract-peptone-dextrose and minimal media, whereas class B auxotrophs grow on minimal medium and readily revert to grow on yeast extract-peptone-dextrose medium. Class B auxotrophs are suppressible by a class of suppressors distinct from nonsense suppressors, and their properties suggest that they are defective in a regulatory function. All 23 mutants studied were recessive and allelic, and they define a new gene designated gcn1. An analysis of a class A auxotroph revealed that it lacked L-glutamine:D-fructose 6-phosphate amidotransferase (EC 2.6.1.16) activity and indicates that GCN1 codes the amino acid sequence of this enzyme. The finding that all mutants were allelic indicates that the amidotransferase is the only enzyme responsible for D-glucosamine synthesis in S. cerevisiae. The occurrence of allelic complementation and media-conditional mutants suggests that the amidotransferase is a multimeric enzyme with an activity subject to metabolic control. Diploids homozygous for gcn1 fail to complete sporulation. They proceed through meiosis normally, as judged by the occurrence of meiotic recombination, the production of haploid nuclei, and the formation of multinucleate cells visible after Giemsa staining. However, the formation of glusulase-resistant ascospores is blocked, and deformed spores lacking the electron-dense outer layer characteristic of the normal spore wall are observed by electron microscopy. Cells that acquire the ability to synthesize D-glucosamine, because of gene conversion during meiosis, complete sporulation in a normal fashion. Thus, the GCN1 gene product appears to be synthesized late in sporulation and may prove to be a useful developmental landmark for the termination of ascospore development.

Alleles↗

PubMed1981

Temperature-sensitive glucosamine auxotroph of Saccharomyces cerevisiae.

Temperature-sensitive revertants were isolated from Saccharomyces cerevisiae D-glucosamine auxotrophs previously obtained in this laboratory (W. L. Whelan and C. E. Ballou, J. Bacteriol. 124:1545-1557, 1975). The auxotrophs lack the enzyme 2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase (EC 5.3.1.19), and the revertants appear to be temperature sensitive in the formation of enzyme activity. The enzyme they produce under permissive conditions decays in activity at a rate comparable to that of the wild-type enzyme, and it has similar kinetic properties. The homozygous diploid mutant fails to sporulate at the nonpermissive temperature. Temperature shift experiments were carried out in an effort to determine what effect glucosamine deficiency had on mannoprotein secretion as reflected in the formation of external asparaginase. Although the results were complicated by the slow decay of the residual ketol-isomerase activity, they did show that mannoprotein synthesis or secretion was altered when the internal pool of D-glucosamine was depleted.

Asparaginase↗

PubMed1978

Growth of Escherichia coli on glucosamine 6-phosphate: selection of a constitutive hexose phosphate transport system mutant.

Glucosamine 6-phosphate was found to be a substrate but not an inducer for the hexose phosphate transport system of Escherichia coli. Wild-type cells grow very poorly on glucosamine 6-phosphate. A mutant was selected that will grow rapidly on glucosamine 6-phosphate because it contains a constitutive hexose phosphate transport system.

Biological Transport, Active↗

PubMed1978

Effect of glucosamine on virus production and antigen expression in avian sarcoma virus-transformed cells.

Treatment by glucosamine of avian sarcoma virus-transformed chicken embryo fibroblast (CEF) cells completely inhibited the formation of progeny-transforming virus particles. Such cells, however, could continue to synthesize non-infectious physical particles containing both viral RNA and the enzyme RNA-dependent DNA polymerase if glucosamine exposure was performed in the presence of glucose. Glucosamine treatment was found to affect antigenic expression in transformed CEF as measured by an indirect immunofluorescence test. Inhibition to a far lesser extent was observed when a lymphocyte stimulation assay for the detection of cell-mediated immunity was used in this system.

Alpharetrovirus↗

PubMed2002

Defective Akt activation is associated with glucose- but not glucosamine-induced insulin resistance.

UNLABELLED: 3T3-L1 adipocytes develop insulin-resistant glucose transport upon preincubation with high glucose or glucosamine, provided insulin (0.6 nM) is present during preincubation. Insulin receptor substrate-1 (IRS-1)-associated phosphatidylinositol (PI) 3-kinase activity is unaffected (30). Total cellular IRS-1, PI 3-kinase, or Akt concentrations were unchanged. Akt activation in subcellular fractions was assessed by immunoblotting with two phospho-Akt-specific antibodies. Upon acute 100 nM insulin stimulation, plasma membrane (PM)-associated phospho-Akt was highest in cells preincubated in low glucose with no insulin, less in high glucose with no insulin, even less in low glucose+insulin, and lowest in high glucose+insulin. Only high glucose+insulin caused insulin-resistant glucose transport. Acute insulin stimulation increased total PM-Akt about twofold after preincubation without insulin in low or high glucose. Preincubation with 0.6 nM insulin decreased Akt PM translocation by approximately 25% in low and approximately 50% in high glucose. Preincubation with glucosamine did not affect Akt phosphorylation or translocation. CONCLUSIONS: chronic exposure to high glucose or insulin downregulates acute insulin-stimulated Akt activation, acting synergistically distal to PI 3-kinase. Maximal insulin activates more Akt than required for maximal glucose transport stimulation. Insulin resistance may ensue when PM-associated phospho-Akt decreases below a threshold. High glucose and glucosamine cause insulin resistance by different mechanisms in 3T3-L1 adipocytes.

3T3 Cells↗

PubMed1983

Inhibition of bone resorption and increased incorporation of 3H-glucosamine into hyaluronate in bone organ cultures treated with dibutyryl cyclic AMP and colchicine.

Addition of dibutyryl adenosine 3':5'-monophosphate (DBCAMP), colchicine or dbcAMP/colchicine to bone organ cultures markedly inhibited bone resorption. Calvaria of newborn mice labeled with 45Ca 3 days before sacrifice were removed and cultured in medium containing 3H-glucosamine. Both agents alone and in combination inhibited 45Ca release. DEAE-cellulose chromatography of the papain-digested medium and bone resolved the 3H-glucosamine-labeled macromolecular material into four peaks. A marked increase in radioactivity was observed in the hyaluronate fraction (peak III) of the chromatographed bone samples. The results indicate that dbcAMP does not mimic the effect of parathyroid hormone on bone resorption, but that it is similar to colchicine in both the inhibition of bone resorption and the increased incorporation of 3H-glucosamine into hyaluronate. Although the role of hyaluronate, if any, in this experimental system remain elusive, the increased radioactivity associated with the hyaluronate fraction may be due to decreased degradation resulting from decreased hyaluronidase synthesis.

Animals↗

PubMed2003

Glucosamine and chondroitin sulfate supplementation to treat symptomatic disc degeneration: biochemical rationale and case report.

BACKGROUND: Glucosamine and chondroitin sulfate preparations are widely used as food supplements against osteoarthritis, but critics are skeptical about their efficacy, because of the lack of convincing clinical trials and a reasonable scientific rationale for the use of these nutraceuticals. Most trials were on osteoarthritis of the knee, while virtually no documentation exists on spinal disc degeneration. The purpose of this article is to highlight the potential of these food additives against cartilage degeneration in general, and against symptomatic spinal disc degeneration in particular, as is illustrated by a case report. The water content of the intervertebral disc is a reliable measure of its degeneration/ regeneration status, and can be objectively determined by Magnetic Resonance Imaging (MRI) signals. CASE PRESENTATION: Oral intake of glucosamine and chondroitin sulfate for two years associated with disk recovery (brightening of MRI signal) in a case of symptomatic spinal disc degeneration. We provide a biochemical explanation for the possible efficacy of these nutraceuticals. They are bioavailable to cartilage chondrocytes, may stimulate the biosynthesis and inhibit the breakdown of their extracellular matrix proteoglycans. CONCLUSION: The case suggests that long-term glucosamine and chondroitin sulfate intake may counteract symptomatic spinal disc degeneration, particularly at an early stage. However, definite proof requires well-conducted clinical trials with these food supplements, in which disc de-/regeneration can be objectively determined by MRI. A number of biochemical reasons (that mechanistically need to be further resolved) explain why these agents may have cartilage structure- and symptom-modifying effects, suggesting their therapeutic efficacy against osteoarthritis in general.

Chondroitin Sulfates↗

PubMed2002

Ceramide and glucosamine antagonism of alternate signaling pathways regulating insulin- and osmotic shock-induced glucose transporter 4 translocation.

In addition to insulin, hyperosmolarity induces glucose transporter 4 (GLUT4) translocation in 3T3-L1 adipocytes. However, in contrast to insulin this stimulation is independent of PI3K/Akt. In this study we assessed whether ceramide and/or glucosamine, two known insulin-signaling antagonists, also affected the PI3K/Akt-independent signal. Insulin, but not hyperosmolarity, clearly increased the activities of PI3K and Akt. C2-ceramide did not alter insulin-stimulated PI3K activity, but did decrease the ability of insulin to activate Akt and GLUT4 translocation. Consistent with osmotic shock-mediated GLUT4 translocation being independent of PI3K/Akt, GLUT4 translocation induced by hyperosmolarity was not altered by C2-ceramide. In contrast to the specific C2-ceramide-induced attenuation of insulin-stimulated GLUT4 translocation, overexpression of glutamine:fructose-6-phosphate amidotransferase, the rate-limiting enzyme in the synthesis of UDP-N-acetylglucosamine, and/or pretreatment of cells with glucosamine, a precursor of UDP-N-acetylglucosamine, inhibited both insulin- and hyperosmolarity-stimulated GLUT4 translocation. Glucosamine did not alter any of the known proximal insulin signal transduction events. These data suggest that although the hyperosmolarity-induced signal bypasses the initial insulin signal transduction steps, it is likely to induce GLUT4 translocation through activation of a common convergent signal transduction step, targeted by UDP-N-acetylglucosamine, downstream of and/or in parallel to PI3K/Akt.

3T3 Cells↗

PubMed1982

Effect of D-glucosamine on the functional maturation of cultured B cells of the neonatal rat.

The present study demonstrates the effect of glucosamine on the functional maturation of cultured B cells of the neonatal rat. When B cells had been maintained at a physiological concentration (5.5 mM) of glucose for 7 days, a drop in the stimulatory effect of 16.7 mM glucose on insulin release and biosynthesis was observed together with a reduced insulin content. By contrast, the sensitivity of glucose-induced insulin release was increased after one week of culture with 5.5 mM glucose and 5 mM glucosamine. And both the insulin content and glucose-induced insulin biosynthesis also remained at the same level as observed at the first day of culture with 5.5 mM glucose alone. In summary, it was suggested that glucosamine-supplemented culture may result in the transition of B cells of neonatal rat from a poor glucose sensitivity to adult-type response of insulin release.

Animals↗

PubMed1988

An autoradiographic study of gonadotrophin regulation of labelled glycoconjugates within preovulatory mouse follicles during the final stages of oocyte maturation, using [3H]glucosamine as the radioactive precursor.

Immature mice were treated with PMSG and hCG to induce follicular development and ovulation. [3H]Glucosamine was injected at the same time as the PMSG or 2 h before autopsy. The synthesis and distribution of labelled glycoconjugates within the preovulatory follicles was hormonally dependent. PMSG stimulated a rapid uptake of [3H]glucosamine into the zona pellucida and follicular fluid of the largest antral follicles although labelled macromolecules could not be demonstrated in any of the cellular components of these follicles. The injection of hCG stimulated a rapid incorporation of labelled macromolecules into the cellular components of the preovulatory follicle, namely into thecal, granulosa and especially the cumulus cells surrounding the oocyte. The density of labelled macromolecules within the follicular fluid also increased, while the specific and uniform labelling of the zona pellucida which was so characteristic of the period of PMSG stimulation changed. Between 4 and 8 h after the injection of hCG, labelled glycoconjugates containing [3H]glucosamine, became increasingly associated with the outer surface of the zona pellucida and with the region of the egg plasma membrane, even in Graafian follicles not destined to ovulate. The change in distribution of labelled macromolecules on the zona surface may be a prerequisite for successful sperm-zona binding and the specific association of labelled glycoconjugates in the region of the egg plasma membrane may be involved in the preparation of the egg surface for sperm-egg interactions involving cortical granule exocytosis and the block to polyspermy.

Animals↗

PubMed2006

Antitumor activities of D-glucosamine and its derivatives.

The growth inhibitory effects of D-glucosamine hydrochloride (GlcNH(2).HCl), D-glucosamine (GlcNH(2)) and N-acetyl glucosamine (NAG) on human hepatoma SMMC-7721 cells in vitro were investigated. The results showed that GlcNH(2).HCl and GlcNH(2) resulted in a concentration-dependent reduction in hepatoma cell growth as measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. This effect was accompanied by a marked increase in the proportion of S cells as analyzed by flow cytometry. In addition, human hepatoma SMMC-7721 cells treated with GlcNH(2).HCl resulted in the induction of apoptosis as assayed qualitatively by agarose gel electrophoresis. NAG could not inhibit the proliferation of SMMC-7721 cells. GlcNH(2).HCl exhibited antitumor activity against Sarcoma 180 in Kunming mice at dosage of 125-500 mg/kg, dose of 250 mg/kg being the best. GlcNH(2).HCl at dose of 250 mg/kg could enhance significantly the thymus index, and spleen index and could promote T lymphocyte proliferation induced by ConA. The antitumor effect of GlcNH(2).HCl is probably host-mediated and cytocidal.

Animals↗

PubMed2004

Spectrophotometric determination of glucosamine and its analogous amino sugars with o-hydroxyhydroquinonephthalein and palladium(II).

A simple and highly sensitive spectrophotometric method for the determination of glucosamine and its analogous amino sugars was established based on fading of the palladium(II)-o-hydroxyhydroquinonephthalein-hexadecyltrimethylammonium complex. In the determination of glucosamine, Beer's law is obeyed in the range of 0.02 - 0.18 microg ml(-1), with an effective molar absorptivity at 630 nm and the relative standard deviation being 8.4 x 10(5) dm3 mol(-1) cm(-1) and 1.08% (n = 10). This method is about 70-times more sensitive than the Elson-Morgan method. The method was successfully applied to the assay of glucosamine in actual samples.

Amino Sugars↗

PubMed1999

In vitro effects of glucosamine and acetylsalicylate on canine chondrocytes in three-dimensional culture.

OBJECTIVE: To determine effects of glucosamine and acetylsalicylate on canine chondrocytes in 3-dimensional culture. SAMPLE POPULATION: Chondrocytes isolated from articular cartilage of 2 adult female dogs recently euthanatized for reasons unrelated to orthopedic abnormalities. PROCEDURE: Chondrocytes were cultured in a 3-dimensional agarose-based medium alone (control), with glucosamine (100 microg/ml; GL), or with acetylsalicylate (18 microg/ml; AS). Supernatant and agarose plugs from 4 wells/group/d were collected on days 3, 6, and 12 of culture. Agarose plugs were evaluated for percentage of viable cells, percentage of cells producing pericellular or territorial matrix, glycosaminoglycan (GAG) concentration, and type-II collagen production. Prostaglandin E2 concentration in supernatants was determined. RESULTS: Chondrocytes in all groups had characteristics indicative of viability and differentiation; however, on day 12, a lower percentage of viable cells was detected in the AS group, compared with the other 2 groups. On day 6, GAG concentration in the AS group was significantly greater than concentrations in the other 2 groups. On day 12, GAG concentrations in the GL and AS groups were significantly less than in the control group. Within the GL and AS groups, cell viability was significantly less on day 12, compared with day 3. Significant differences in PGE2 concentration among or within groups and evidence of type II collagen production were not detected. CONCLUSIONS: 3-dimensional culture of canine chondrocytes allows for production of hyaline cartilage matrix constituents and growth of cells with morphologic characteristics similar to those of articular cartilage. Acetylsalicylate and glucosamine, at the single concentration evaluated, had detrimental effects on chondrocyte viability, GAG production, or both.

Animals↗

PubMed2000

[Polymeric chondroitin sulfate vs. monomeric glucosamine for the treatment of osteoarthritis].

Two potentially chondro-protective substances are compared with each other: polymeric chondroitin sulfate and monomeric glucosamine. Chondroitin-sulfate is characterized by tropism for cartilage, i.e. it is preferentially incorporated into cartilagenous tissue. This quality could be of interest in the SPECT-analysis of osteoarthritic knee joints. In contrast to the classic agents Ibuprofen and Indomethacin, the antiinflammatory action of chondroitin-sulfate is less prominent, but the drug does not show any toxic side effects. Glucosamine on the other hand is a multifunctional precursor of the glycosaminoglycan synthesis in general. It lacks the cartilage tropism of chondroitin-sulfate. Into what sort of a glycosaminoglycan glucosamine is eventually integrated, depends therefore on the nature of the cells participating in the biosynthesis.

Aggrecans↗

PubMed2001

Glucosamine and chondroitin for osteoarthritis?

The current body of evidence currently supports modest efficacy for glucosamine and chondroitin in the treatment of OA symptoms. The products are safe and could play a valuable role in the management of this disorder. Nevertheless, further independent studies are needed to confirm these findings and to determine the clinical applicability of these compounds. Physicians need to become involved in these treatment decisions but are confused by wide variability in the formulation and purity of the numerous preparations available to consumers. The notion that glucosamine and chondroitin might have disease-modifying effects in OA is highly appealing and supported by preliminary data. Research is needed to confirm these findings and to evaluate the impact of glucosamine and chondroitin on all aspects of OA progression.

Chondroitin↗

PubMedDate not supplied

Asthma exacerbation associated with glucosamine-chondroitin supplement.

BACKGROUND: Although dietary supplements are in widespread use, and some have been endorsed by the medical community and complementary and alternative practitioners, not much is known about their potential side effects or drug interactions. METHODS: A case of asthma exacerbated by the use of a glucosamine-chondroitin supplement for osteoarthritis pain is described. The literature was searched from 1980 to 2002 using the terms "glucosamine," "chondroitin sulfate," "alternative medicine," and "dietary supplements," combined with "asthma." RESULTS AND CONCLUSIONS: The biological link between both chondroitin and glucosamine and secretions from the respiratory tree of persons with asthma lends biologic plausibility to the hypothesis that the patient's asthmatic episode was related to the dietary substance. Physicians would be wise to question their patients about use of dietary supplements as self-medication and consider the possibility of such supplements causing exacerbations of underlying conditions.

Asthma↗