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Lipid A and related compounds. XXVI. Syntheses of biologically active penta-O-acetyl-N-glycoloylneuraminyl- and penta-O-acetyl-3-deoxy-D-galacto-2- nonulopyranosonic acid-(alpha 2----6)-D-glucosamine-4-phosphate analogs of lipid A.

The syntheses of novel penta-O-acetyl-N-glycoloylneuraminyl- and penta-O-acetyl-3-deoxy-D-glycero-D-galacto-2-nonulopyranosonic acid-(alpha 2----6)-D-glucosamine-4-phosphate analogues of lipid A containing sialic acid in place of 3-deoxy-D-manno-2-octulosonic acid are described. Preliminary examination of the biological activity revealed that two synthetic disaccharides showed mitogenic activities and weak antitumor activities.

Antineoplastic Agents↗

Polymeric N-acetyl-D-glucosamine (chitin) induces histionic activation in dogs.

Analyses on the effects of polymeric N-acetyl-D-glucosamine (chitin), which was obtained from squid pen, on histiogenic activation in dogs were carried out with subcutaneous implants (5 x 5 cm2) of polyester non-woven fabric (NWF) supplemented with chitin (chitin group) and NWF (control group). These materials were implanted at 4 sites, on the lumbodorsal and lumbosacral subcutaneous tissues on both sides of the midline in each dog under general anesthesia. The implants and their surrounding tissues were isolated on post-implantation days (PIDs) 2, 4, 8, and 18 under general anesthesia. In the chitin group, the implant was organized gradually and its organization was completed on PID 18, when obvious angiogenesis toward the NWF was observed. On the other hand, in the control group, obvious angiogenesis toward the NWF was not observed macroscopically. Numbers of mononuclear (MN) and polymorphonuclear (PMN) cells concentrated around the implants on PID 2 were larger in the chitin than control group. In the chitin group, formation of granulating tissue around the implant was indicated on PID 4, whereas such a phenomenon was not observed in the control group. From these results, chitin accelerates the migration of MN and PMN cells to the NWF site with rapid follow-up organization of the NWF accompanied by angiogenesis.

Animals↗

Polymeric N-acetyl-D-glucosamine (chitin) induces prostaglandin E2 in dogs.

The level of prostaglandin E2 (PGE2) in the exudate induced by subcutaneous implantation of a complex formed from non-woven fabric of polyester (NWF) and polymeric N-acetyl-D-glucosamine (chitin) (chitin/NWF) or by implantation of NWF in dogs was measured by radioimmunoassay. The amount of PGE2 in the exudate induced by chitin/NWF was about five times as high as that in the exudate induced by NWF (p < 0.05), while the level of PGE2 in the exudate was similar to that in serum.

Animals↗

Effect of epidermal growth factor on glucosamine-6-phosphate synthetase activity in the colon of neonatal mice.

Epidermal growth factor (EGF), administered subcutaneously to neonatal mice at daily doses of 1,2 and 4 micrograms/g body weight for 3 days, significantly increased glucosamine-6-phosphate synthetase activity in the colon. A single injection of EGF at doses of 2 and 4 micrograms/g body weight also significantly increased enzyme activity. When administered to mature mice, EGF (4 micrograms/g body weight for 3 days) had no apparent effect on the enzyme activity. From these results, we suggest that EGF acts as a trophic factor for the maturation of the colonic mucosa of neonatal mice.

Animals↗

Amino acid residues conferring the nucleotide binding properties of N-acetyl-D-glucosamine 2-epimerase (renin binding protein).

Our recent studies have demonstrated that the middle domain of N-acetyl-D-glucosamine (GlcNAc) 2-epimerase participates in the specificity for and binding of nucleotides. To identify the residue conferring nucleotide binding, amino acid substitutions were introduced in the human and rat GlcNAc 2-epimerases. The mutational analyses indicate that residue 171 of GlcNAc 2-epimerase is critical for the nucleotide binding of GlcNAc 2-epimerase.

Adenosine Triphosphate↗

Androgen influences on glucosamine 6-phosphate synthase in the epididymis of the rat.

Glucosamine 6-phosphate synthase activity in the total, caput, and cauda epididymis was estimated. Efferent duct ligation for 7 or 16 days caused significant reduction in the enzyme activity of caput epididymidis only and had no effect on the cauda epididymidis. Treatment with dihydrotestosterone (DHT) at a dose of 100 micrograms per day restored the enzyme activity in the caput epididymidis.

Animals↗

N3-oxoacyl derivatives of L-2,3-diaminopropanoic acid and their peptides; novel inhibitors of glucosamine-6-phosphate synthase.

Novel inhibitors 1-4 of glucosamine-6-phosphate synthase from Candida albicans have been designed based on acylation of the N3 amino group of L-2,3-diaminopropanoic acid with the corresponding ketoacids. These inhibitors have been shown to alkylate the fungal enzyme in a time-dependent manner. Compound 3 containing trans-beta-benzoyl acrylic acid as an acyl residue was found to be the most potent inhibitor in the series. Dipeptides composed of the active inhibitors and norvaline demonstrated potent antifungal activity against selected strains of Candida spp. and Saccharomyces cerevisiae. Their activity was reversed upon addition of N-acetylglucosamine to the medium.

Alkylation↗

Constrained search of conformational hyperspace of inactivators of glucosamine-6-phosphate synthase.

Glucosamine-6-phosphate (GlcN-6-P) synthase (EC 2.6.1.16) is a key enzyme in amino sugar metabolism in micro-organisms and its selective and irreversible inhibitors can become valuable antifungal drugs. We performed a constrained search of the conformational hyperspace of glutamine and of the set of specific inactivators of the enzyme, as well as of some non-specific inhibitors of many cysteine containing enzymes. From these calculations we obtained spatial relationships of functional groups, the presence and specific orientation of which in the active site of the enzyme is important for effective and selective action of the inhibitor. Subsequent quantum chemical calculations confirmed the correctness of the pharmacophore conformation we obtained. Pharmacophore conformation of FMDP molecule, the most potent inhibitor in the selective inhibitors group, is placed close to the energy minimum on the conformational energy map.

Antifungal Agents↗

Inhibition of glucosamine-6-phosphate synthetase from bacteria by anticapsin.

On the basis of kinetic studies on glucosamine-6-phosphate synthetase (EC 5.3.1.19) from six bacteria sources it has been shown that the epoxyamino acid anticapsin, a glutamine analog, is a competitive inhibitor of the enzyme in regard to glutamine with Km value of 10(-4) M and Ki varying from 10(-7) to 10(-6) M. Unlike other glutamine analogs like 6-diazo-5-oxo-L-norleucine, chloropentanoic acid, L-alpha-amino-3-chloro-4,5-dihydro-5-isoxazole acetic acid or albizziin, anticapsin is not generally inhibitory to various amidotransferases. It does not inhibit xanthosine 5'-monophosphate amidotransferase, glutaminase or gamma-glutamyltranspeptidase.

Alanine↗

Primary T-cell and activated macrophage response associated with tumor protection using peptide/poly-N-acetyl glucosamine vaccination.

The mode of peptide-based cancer vaccine administration critically affects the ability to achieve a clinically relevant tumor-specific response. We have previously shown (Cole et al., Clin. Cancer Res., 3: 867-873, 1997) that a specific formulation of the polysaccharide poly-N-acetyl glucosamine (p-GlcNAc, designated as F2 gel) is an effective vehicle for sustained cytokine and peptide delivery in vitro. The purpose of this study was to evaluate the efficacy of F2 gel/peptide vaccination in the murine EG.7-OVA tumor model and to elucidate potential mechanisms involved in the observed cell-mediated response. C57BL/6 mice were given injections of 200 microl in the base of tail/footpad using either F2 gel alone or 200 microg of: SIINFEKL minimal peptide (OVA) in PBS, OVA peptide/endoplasmic reticulum insertion signal sequence fusion (ESOVA) in PBS, OVA in F2 gel, or ESOVA in F2 gel. Splenocytes were tested 10 days later for a secondary response using a Cr51 assay as well as a primary CTL response using the lactate dehydrogenase cytotoxicity assay. Splenocytes from immunized mice were harvested at specific time points and assayed for cell surface and intracellular markers. On day 10 postvaccination, animals were challenged with EG.7-OVA murine thymoma cells. Tumor size and appearance were recorded. Vaccination with F2 gel/peptide (either OVA or ESOVA) resulted in a primary T-cell response (up to 25% tumor cell-specific lysis) and no tumor growth in 69% of the mice. By 48 h, the proportion of splenic T cells had increased 4-fold compared with B cells. Presence of an increased Th1 CD4 helper population was demonstrated by IFN-gamma production. CD4 cells were activated at 24 and 48 h as shown by IL-2 receptor alpha chain expression (from 2% basal expression to 15.4% at 48 h). Activated splenic macrophages increased from 3 to 8% within 10 h, and their level of B7-2 expression doubled. Depletion of macrophages before vaccine injection abolished any tumor-specific primary CTL response. F2 gel/peptide tumor vaccine can prime the immune system in an antigen-specific manner by generating a measurable primary T-cell response with minimal peptide; this process involves macrophage presence and activation as well as induction of Th1 CD4 cells. This is the first demonstration of a primary CTL response generated with minimal peptide vaccination using a noninfectious delivery system. These results justify additional studies to better define the mechanisms involved in F2 gel/peptide vaccination in preparation for clinical trials.

Adjuvants, Immunologic↗

A pilot study evaluating the efficacy of a fully acetylated poly-N-acetyl glucosamine membrane formulation as a topical hemostatic agent.

BACKGROUND: Topical hemostatic agents are frequently needed for control of intraoperative bleeding. Currently available topical products each have potential drawbacks, making a more effective topical hemostatic agent desirable. This study was performed to evaluate the effectiveness of a particular formulation of a newly available polysaccharide polymer, poly-N-acetyl glucosamine (p-GlcNAc), as a topical hemostatic agent for use in the operating room. Swine splenic incision and splenic capsular stripping hemorrhage models were initially used, with a subsequent pilot human study then performed. METHODS: For the swine splenic incision model, anesthetized immature female Yorkshire white swine had a 3 x 8 mm incision created on the spleen. One of 3 agents (p-GlcNAc membrane, oxidized cellulose, or absorbable collagen) was sequentially applied to individual wounds and digitally compressed for 20 seconds. The wound was observed without pressure for 2 minutes. Up to 8 wounds per animal were created in 7 animals. For the swine splenic capsular stripping model a 2 x 2 cm area of capsular stripping on the surface of the spleen to a depth of 3 mm was created. Either p-GlcNAc membrane or oxidized cellulose was applied and digitally compressed for 60 seconds, followed by observation without pressure for 2 minutes. Six wounds per animal were created in 2 animals. If bleeding persisted in either model, a new cycle of compression was applied. These steps were repeated until hemostasis was achieved. No change in hemodynamics or coagulation factors was observed in either model. Subsequently, 10 consecutive patients undergoing elective small-bowel surgery were enrolled on pilot study. A 5 x 3 x 3 mm cruciate incision was created midway between the mesenteric and antimesenteric borders of the small bowel. Either p-GlcNAc membrane formulation or oxidized cellulose was applied (the sequence alternated per patient) with a 400-mg weight used for even, direct pressure. A second cruciate incision was then created on the contralateral side of the bowel to evaluate the second material. The number of applications required for hemostasis was assessed. Hemodynamics, small-bowel pathologic condition, and hematologic parameters were evaluated. RESULTS: The p-GlcNAc membrane required fewer cycles of compression in the swine splenic incision model to achieve hemostasis than either absorbable collagen or oxidized cellulose (1.25 vs 2.58 and 3.41, respectively; P < .01) and caused more effective immediate cessation of bleeding (79% for p-GlcNAc vs 17% for both absorbable collagen and oxidized cellulose). With the more traumatic splenic capsular stripping model, p-GlcNAc required fewer cycles of compression to achieve hemostasis than oxidized cellulose (average, 2.5 versus 6.8 respectively; P < .01) and was able to achieve hemostasis with greater efficacy (50%) in 2 applications than did oxidized cellulose (0%; P < .01). When used in the human pilot study, p-GlcNAc membranes required fewer cycles of compression than oxidized cellulose (2.5 vs 5.4, respectively; P < .002), was able to stop bleeding with greater efficacy in 1 cycle of compression (50% vs 0%, respectively; P < .01), and ultimately accomplished hemostasis in 80% of the cases as opposed to 20%. CONCLUSIONS: On the basis of its greater hemostatic efficacy as compared with collagen or oxidized cellulose-based products, p-GlcNAc holds promise as an effective topical hemostatic agent and deserves further evaluation.

Acetylation↗

Effects of N-acetyl-glucosamine-coated glycodendrimers as biological modulators in the B16F10 melanoma model in vivo.

Glyco-coat changes on cancer cells due to aberrant glycosylation are potential targets for immune recognition through lectin-like receptors on immune cells. These cells include natural killer (NK), CD8+ and CD4+ lymphocytes, all reported to have, together with cytokines, important functions in antitumor immunity. The aim of this study was to evaluate a possible role of synthetic monodisperse multivalent neo-glycoconjugates, namely glycodendrimers, as a new approach to anticancer immune modulation through carbohydrate-mediated immune recognition. Octavalent polyamidoamine dendrimers functionalized with N-acetyl-glucosamine residues (PAMAM-GlcNAc8), with in vitro high affinity for the recombinant lymphocyte receptor NKR-P1A, were employed. To follow the fate of the compound, a fluorescent marker was conjugated to the tetra-branched semi-component of the dendrimer. Tumor development and immunity were evaluated in C57BL/6 mice. Animals were inoculated with B16F10 melanoma cells and underwent different protocols of PAMAM-GlcNAc8 administration. Advantages on survival and reduction of tumor growth were obtained in dose-dependent manner, by IP route. Increase of CD69+ cells in the spleen and their appearance inside the tumors, early progressive release of IL-1beta, a later production of INFgamma and IL-2 concomitant to an increment of CD4+ cells were observed. Cytotoxicity assays, performed ex vivo, showed an enhanced NK cell activity proportioned to the percentage of activated NK cells. Our data suggest that well-defined multivalent neo-glycoconjugates can stimulate an antitumor immune response engaging both innate and acquired immunity.

Acetylglucosamine↗

Antifungal peptides with novel specific inhibitors of glucosamine 6-phosphate synthase.

N3-4-Methoxyfumaroyl-L-2,3-diaminopropanoic acid (FMDP) has been found to be a strong and selective inhibitor of glucosamine 6-phosphate synthase from Candida albicans. Incorporation of FMDP into a dipeptide structure has produced effective antifungal agents (portage transport). A number of dipeptides containing FMDP have been synthesized, with Nva-FMDP showing the highest in vitro activity against different fungi, including Candida albicans (MIC90 = 2.2 micrograms/ml for 50 clinical strains), Cryptococcus neoformans and Aspergillus spp. This compound, when tested in a general candidiosis model infection in mice, gave PD50/10 and CD50/10 values of 5.0 and 1.63 mg/kg, respectively. Meanwhile, the LD50 value after i.v. administration was higher than 300 mg/kg.

Alanine↗

pHmetrical determination of the glucosamine-6-phosphate isomerase deaminase reverse reaction.

In the reverse direction, the reaction catalyzed by glucosamine 6-phosphate isomerase deaminase consumes ammonia and forms GlcN6P. As a consequence of the formation of a product with a lower pK than the substrates, a measurable pH drop in the reaction medium is produced. This property can be used to follow potentiometrically the course of the reaction. This property can be used to follow potentiometrically the course of the reaction. The usefulness of the method is demonstrated obtaining the inhibition pattern by GlcN6P when Fru6P is the varied substrate.

Escherichia coli↗

Immunological mimicry between N-acetyl-beta-D-glucosamine and cytokeratin peptides. Evidence for a microbially driven anti-keratin antibody response.

We discovered recently that a subset of mouse anti-streptococcal mAbs cross-reacted with N-acetyl-beta-D-glucosamine (GlcNAc) and certain cytoskeletal proteins, and recognized both carbohydrate and peptide antigenic determinants. To further study the nature and biologic significance of immunologic mimicry between carbohydrate and peptide Ags, eight human hybridomas secreting anti-GlcNAc mAbs were produced by in vitro stimulation of PBL with streptococcal peptidoglycan-polysaccharide complexes and pokeweed mitogen. All human anti-GlcNAc mAbs described in this study were shown to express marked cross-reactivity with keratin from human skin in the ELISA and Western immunoblot. Mapping of the mAbs with overlapping synthetic decapeptides of the entire amino acid sequence of human cytokeratin 14 revealed that human anti-GlcNAc mAbs recognized specific cytokeratin decapeptides. Four human anti-GlcNAc mAbs recognized a single cytokeratin decapeptide whereas two mAbs reacted with several individual peptide epitopes in different fragments of cytokeratin 14. In addition, two mAbs, 1.C8 and 9.B12, reacted with multiple cytokeratin decapeptides, predominantly in the head domain of the molecule, and their reactivity correlated with positive binding of the mAbs to cytokeratin 14 in the Western immunoblot and with positive staining of human epidermis in the indirect immunofluorescent assay. Finally, we demonstrated that Abs to keratin and synthetic keratin decapeptides were induced in BALB/c mice immunized with GlcNAc-BSA but not with BSA, suggesting that the anti-keratin Ab response in vivo may be driven by nonkeratin Ags containing terminal O-linked GlcNAc.

Acetylglucosamine↗

A subset of mouse monoclonal antibodies cross-reactive with cytoskeletal proteins and group A streptococcal M proteins recognizes N-acetyl-beta-D-glucosamine.

It is well known that antibodies to N-acetyl-beta-D-glucosamine (GlcNAc) cross-react with cardiac valves, skin, and other host tissues. However, molecular targets of these antibodies have not been identified. For this reason, anti-streptococcal mAb cross-reactive with group A streptococci and heart proteins were studied for their reactivity with GlcNAc, the immunodominant epitope of group A streptococcal carbohydrate. Characterization of the mAb that recognized GlcNAc revealed that each mAb had its own unique antigen-binding profile and pattern of immunofluorescence on rat heart cells. In the ELISA and Western blot these mAb reacted with cytoskeletal and heart proteins such as actin, keratin, myosin, and vimentin, as well as with streptococcal recombinant M5 and M6 proteins. Binding of the mAb to cytoskeletal proteins was inhibited by GlcNAc conjugated with BSA in a dose-dependent manner, and the mAb preferentially reacted with high-density GlcNAc-BSA conjugates. Antigenic determinants on the proteins recognized by the mAb were resistant to sodium periodate and N-acetylglucosaminidase treatment, suggesting reactivity with peptide and not carbohydrate structures. On reaction of the mAb with a panel of synthetic streptococcal, viral, and myosin peptides, one of the mAb, 49.8.9, was found to react most strongly with a synthetic peptide sequence synthesized from the coxsackievirus B3 capsid protein VP1, which shows homology with and cross-reacts with sequences in the streptococcal M6 protein and human cardiac myosin. This most interesting mAb, previously shown to neutralize coxsackie viruses, recognized the amino acid sequence RRKLEFF, which may mimic the GlcNAc epitope. The data collected show that we have identified a new group of multireactive autoantibodies that recognize GlcNAc and cytoskeletal proteins, as well as defined peptide epitopes.

Acetylglucosamine↗

Prolactin suppression during pre and post-implantation periods on rat uterine glucosamine synthase activity.

Administration of bromocriptine (Bc), an ergot derivative having dopamine receptor agonist activity, to rats on day 1-5 of pregnancy prevented implantation of blastocysts and significantly suppressed uterine glucosamine 6-phosphate synthase activity. There was no effect on implantation or the enzyme activity when Bc was injected on day 7 or later of pregnancy. Injection of prolactin following Bc partially restored the enzyme activity and increased number of implantation sites. These results indicate that suppression of prolactin on day 1 to 5 of pregnancy causes failure of implantation. Bc on day 9 or later had no effect possibly due to the availability of placental LH/hCG to support the luteal cells.

Animals↗

The firA gene of Escherichia coli encodes UDP-3-O-(R-3-hydroxymyristoyl)-glucosamine N-acyltransferase. The third step of endotoxin biosynthesis.

The possibility that the firA gene of Escherichia coli (Dicker, I. B., and Seetharam, S. (1991) Mol. Microbiol. 6, 817-823) might function in lipid A biosynthesis was examined based on its homology to the lpxA gene, which encodes UDP-N-acetylglucosamine O-acyl-transferase, the first enzyme in lipid A formation. Extracts of a temperature-sensitive firA mutant, RL-25, were assayed for their ability to acylate UDP-GlcNAc, using a coupled assay. The results suggested that extracts of RL-25 might be defective in the third enzyme of this pathway, the UDP-3-O-(R-3-hydroxymyristoyl)-glucosamine N-acyltransferase. Living cells of RL-25 also displayed a 5-fold decreased rate of lipid A biosynthesis at the nonpermissive temperature as judged by a 32Pi incorporation assay. In order to examine N-acyltransferase activity directly, the substrate [alpha-32P]UDP-3-O-(R-3-hydroxymyristoyl)-GlcN was synthesized enzymatically. N-Acyltransferase specific activity in RL-25 extracts was reduced to less than 10% of wild-type. When the wild-type firA gene was cloned into a T7-based expression vector, N-acyltransferase specific activity increased almost 360-fold relative to wild-type extracts, demonstrating that firA is the structural gene for the enzyme. The N-acyltransferase displays absolute specificity for the R-3-OH moiety of R-3-hydroxymyristoyl-ACP, as does the O-acyltransferase, consistent with the placement of R-3-hydroxymyristate in E. coli lipid A.

Acyltransferases↗