The structurally similar polysialic acid capsules of group B meningococci and Escherichia coli K1 are poor immunogens, and attempts are currently being made to improve their immunogenicity by chemical modifications. An IgG monoclonal antibody to these polysialic acid capsules was used for the study of the presence of structurally similar components in tissue glycoproteins to investigate the reasons for the poor immunogenicity and to evaluate potential dangers in active or passive immunization. By immunoblotting polysialic acid was detected outside the brain in newborn rat kidney, heart, and muscle. It appeared in immunoblots as one component and with similar mobility to the neural cell adhesion molecule N-CAM. Specificity studies of the antibody and endosialidase treatment showed that the polysialic acid glycans detected were composed of chains as long as eight sialic acid residues or more. The polysialic acid was not detected in the corresponding tissues of the adult animal. These results ...
Alkaline borohydride-reduced keratan sulphate (KS) chains derived from bovine femoral head cartilage were fractionated by lectin affinity chromatography with Sambucus nigra agglutinin (SNA) into binding and non-binding populations. Analysis of the SNA-binding and non-binding KS chains using 600 MHz 1H n.m.r. spectroscopy showed that the former population contained alpha(2-6)-N-acetylneuraminic acid residues and the latter contained primarily alpha(2-3)-N-acetylneuraminic acid residues as chain terminators. Both populations contained a similar proportion of alpha(2-3)-N-acetylneuraminic acid residues within their protein-linkage regions, and similar sulphation and fucosylation levels. Analysis of these two fractions by gel-permeation chromatography (g.p.c.) on a TSK-30 XL column showed them to have the same size distributions. It was concluded from the n.m.r. spectra and g.p.c. data that the populations differed primarily in the mode of linkage of the chain-terminating sialic acids. ...
Most adenoviruses use the coxsackie-adenovirus receptor (CAR) as a major cellular receptor. We have shown recently that adenovirus types 8, 19a, and 37, which are the major causes of epidemic keratoconjunctivitis, use sialic acid rather than CAR as a major cellular receptor. The predicted isoelectric point of the receptor-interacting knob domain in the adenovirus fiber protein is unusually high (9.0-9.1) in type 8, 19a, and 37. The pKa of sialic acid is low, 2.6, implying a possible involvement of charge in fiber knob-sialic acid interactions. Here we show that (i) positively charged adenovirus knobs require sialic acid for efficient cell membrane interactions; (ii) viral and knob interactions with immobilized sialic acid or cell-surface sialic acid are sensitive to increased ionic strength; (iii) negatively charged molecules such as sulfated glycosaminoglycans inhibit the binding of virions to target cells in a nonspecific, charge-dependent manner; and that (iv) the ability of adenovirus knobs ...
Alkaline borohydride-reduced keratan sulphate (KS) chains derived from bovine femoral head cartilage were fractionated by lectin affinity chromatography with Sambucus nigra agglutinin (SNA) into binding and non-binding populations. Analysis of the SNA-binding and non-binding KS chains using 600 MHz 1H n.m.r. spectroscopy showed that the former population contained alpha(2-6)-N-acetylneuraminic acid residues and the latter contained primarily alpha(2-3)-N-acetylneuraminic acid residues as chain terminators. Both populations contained a similar proportion of alpha(2-3)-N-acetylneuraminic acid residues within their protein-linkage regions, and similar sulphation and fucosylation levels. Analysis of these two fractions by gel-permeation chromatography (g.p.c.) on a TSK-30 XL column showed them to have the same size distributions. It was concluded from the n.m.r. spectra and g.p.c. data that the populations differed primarily in the mode of linkage of the chain-terminating sialic acids.. ...
Iwata, Y., Suzuki, O. and Wakabayashi, S. (2013), Decreased surface sialic acid content is a sensitive indicator of muscle damage. Muscle Nerve, 47: 372-378. doi: 10.1002/mus.23632 ...
Psychiatric disorders are a group of human diseases that impair higher cognitive functions. Whole-genomic analyses have recently identified susceptibility genes for several psychiatric disorders, including schizophrenia. Among the genes reported to be involved in psychiatric disorders, a gene encoding a polysialyltransferase involved in the biosynthesis of polysialic acid (polySia or PSA) on cell surfaces has attracted attention for its potential role in emotion, learning, memory, circadian rhythm, and behaviors. PolySia is a unique polymer that spatio-temporally modifies neural cell adhesion molecule (NCAM) and is predominantly found in embryonic brains, although it persists in areas of the adult brain where neural plasticity, remodeling of neural connections, or neural generation is ongoing, such as the hippocampus, subventricular zone, thalamus, prefrontal cortex, and amygdala. PolySia is thought to be involved in the regulation of cell-cell interactions; however, recent evidence suggests that it is
Tumor cells of various origins feature increased expression of sialic acid sugars on membrane glycoproteins and glycolipids and their secretion into the tumor microenvironment. Sialic acids are synthesized in and expressed by essentially every vertebrate cell, and are involved in multiple different physiologic processes. However, hypersialylation of tumor cells relative to their untransformed normal counter parts specifically benefits tumor cell growth and correlates with a poor prognosis for patients with cancer (1, 2). Sialic acids comprise a family of more than 50 carbohydrates that share a nine-carbon backbone (C1-9) to which specific chemical modifications are enzymatically attached inside the cell. The most common sialic acid derivate found in mammals is N-Acetylneuraminic acid (Neu5Ac) which bears an acetyl group on the fifth carbon atom (C5). In general, sialic acids terminate the outer end of glycans (sialoglycans), where they are enzymatically linked to other carbohydrates, such as the ...
N-Acetyl-Neuraminic Acid | C11H19NO9 | CID 439197 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.
PolySia expression and function have been extensively studied in the nervous system, but the distribution and role of polySia in the immune compartment is still undefined. Herein we demonstrated the presence of polySia on human NK cells and its absence on other immune subsets, a finding that is in accord with two earlier reports (26, 27). NK cells up-regulated the expression of polySia and its scaffold NCAM upon activation by IL-2 treatment. This coregulation suggested that the heightened polySia signals were due to an up-regulation of both scaffold and glycan, rather than solely attributable to expanded polySia chain length. In support of this conclusion, a comparison of DP on resting and activated cells showed that upon activation total polySia was increased and the DP became more homogenous, tending toward small- to medium-length chains. To our knowledge, this is the first elucidation of polySia DP on primary human cells. The DP values we observed were slightly larger than analogous ...
In line with our recent studies, demonstrating that interaction between sialic acid residues and SIGLEC11 contributes to decreased inflammation and neurotoxicity in vitro (Wang & Neumann, 2010; Shahraz et al, 2015), we now provide further insights into the in vivo effects of polysialic acid. SIGLEC11 and oligoSia and polySia were detected in the neuroretina of human post‐mortem donors. In comparison with the human retina, the murine retina showed a more speckled and more even distribution of sialic acids as reported before for rodent retinas (Bartsch et al, 1990; Sawaguchi et al, 1999).. We carefully assessed the immunomodulatory potential of polySia avDP20 in the laser coagulation mouse model in humanized transgenic mice expressing SIGLEC11 on microglia and tissue macrophages. Laser coagulation damage induces AMD‐relevant pathomechanisms including choroidal neovascularization preceded by Iba1‐positive cell accumulation at the RPE/choroid (Eter et al, 2008; Liu et al, 2013; Lückoff et al, ...
Catalyzes the removal of terminal sialic acid residues from viral and cellular glycoconjugates. Cleaves off the terminal sialic acids on the glycosylated HA during virus budding to facilitate virus release. Additionally helps virus spread through the circulation by further removing sialic acids from the cell surface. These cleavages prevent self-aggregation and ensure the efficient spread of the progeny virus from cell to cell. Otherwise, infection would be limited to one round of replication. Described as a receptor-destroying enzyme because it cleaves a terminal sialic acid from the cellular receptors. May facilitate viral invasion of the upper airways by cleaving the sialic acid moities on the mucin of the airway epithelial cells. Likely to plays a role in the budding process through its association with lipid rafts during intracellular transport. May additionally display a raft-association independent effect on budding. Plays a role in the determination of host range restriction on replication and
Using sialic acid analogues to define the molecular basis of complement resistance mediated by sialylation of neisseria gonorrhoeae lipopolysaccharide and to design novel therapeutics
Endosialidase (endo-N-acetylneuraminidase) is a tailspike enzyme of bacteriophages specific for human pathogenic Escherichia coli K1, which specifically recognizes and degrades polySia (polysialic acid). polySia is also a polysaccharide of the capsules of other meningitis- and sepsis-causing bacteria, and a post-translational modification of the NCAM (neural cell-adhesion molecule). We have cloned and sequenced three spontaneously mutated endosialidases of the PK1A bacteriophage and one of the PK1E bacteriophage which display lost or residual enzyme activity but retain the binding activity to polySia. Single to triple amino acid substitutions were identified, and back-mutation constructs indicated that single substitutions accounted for only partial reduction of enzymic activity. A homology-based structural model of endosialidase revealed that all substituted amino acid residues localize to the active site of the enzyme. The results reveal the importance of non-catalytic amino acid residues for ...
All cells are decorated on their surfaces with a complex array of oligosaccharides (glycans) that are attached to membrane glycoproteins and glycolipids or which make up the different components of soluble extracellular materials such as mucus and which are involved in the initial interactions of viruses or other pathogens with cells or mucosal surfaces (1). The chemical diversity of these glycans contributes to their complex functional roles in controlling cell-cell, cell-pathogen, and cell-environment interactions. Linear and branched glycoconjugates of vertebrate cells are often terminated in sialic acids (Sias). Sias have critical roles in maintaining a variety of cell functions due to their abundance as exposed terminal sugars, where they are involved in highly specific and regulated cellular lectin interactions (2, 3). They have also been exploited by many different pathogens as well as by nonpathogenic microbes for host recognition and attachment, including playing a role as receptors for ...
Sialic Acid Analysis from SGS - a powerful technique to help you identify and quantify sialic acid species in your biopharmaceutical product.
Hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha-(2->8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates ...
Thanks everyone, so glad I come here. I will tell him about the lupron shot. My Uncle does not complain but we know he is very tired and he is losing the strength in his arms (he is a commercial builder). The doctor asked him if he was reading the Snuffy Myers book when he asked about Intermittent. I told him he is going to have to wait until he can approach that question again.. ...
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In previous studies, we have shown that the highly sialylated renal anti-adhesin Podocalyxin (PC) is expressed in the developing brain [13], [14 ...
Lindberg and colleagues report on a fascinating observation that serum sialic acid level predicts cardiovascular (and noncardiovascular) mortality. The studys classical design of measuring a factor and relating it to subsequent mortality was greatly strengthened by its large community-based sample. However, this study raises several concerns. First, it is unclear whether any hypothesis about sialic acid had been set out by the investigators 20 years ago or whether this was part of the series of protein measurements that was done without a particular hypothesis. Second, because the measurement of sialic acid was done in the 1960s, another sialated protein may have been measured. Third, many more risk factors for coronary disease are known now than were known 20 years ago; for example, the only lipid measured in that study was total cholesterol. Thus, the relation of other lipids and lipoproteins to sialic acid could not be determined. Also, no data on cigarette smoking were provided. Fourth, ...
Calcium is essential for the maintenance of contraction in the heart, and it has been suggested that the glycoprotein matrix on the external surface of cardiac cells is a critical factor in the supply of activator calcium to the beating heart. Sialic acid residues are important calcium-binding sites in the matrix and treatment with neuraminidase, an enzyme which cleaves sialic acid from oligosaccharide chains, has been reported to abolish spontaneous contraction in cultured heart cells, without causing general breakdown in the plasma membrane. However, we report here that in intact, electrically stimulated guinea pig atrial preparations, neuraminidase treatment produces no significant changes in resting tension or force of contraction. It is also without effect on the response to calcium removal and replacement, and inotropic or toxic concentrations of cardiac glycosides. In these experiments, up to 79% of the total tissue sialic acid was removed, and electron microscopy studies showed that this
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We have generated two transgenic mice strains (one is overexpressing the mutated key enzyme of the sialic acid biosynthesis, which leads to high sialic acid levels and one has a defect in the sialic acid biosynthesis). Both strains will be compared with wild-type animals. We plan to analyse O-GlcNAc, sialic acid, sialic acid binding proteins and sialic acid-dependent differentiation markers in all organs over the whole lifespan and quantify age-dependent muscle performance in vivo. The outcome of metabolic sialic acid engineering will be analysed in embryonic stem cells (differentiation) and neuronal cells (neurite outgrowth e.g. regeneration). We also plan to analyse the involvement of sialylation and O-GlcNAcylation on the function of endothelial cells. After metabolic engineering we will analyse their barrier capacity and age-related impact on neuronal cells by real-time cell analysis. Since high levels of glucose induce glycation of proteins, we will analyse the function of an artificial ...
We have generated two transgenic mice strains (one is overexpressing the mutated key enzyme of the sialic acid biosynthesis, which leads to high sialic acid levels and one has a defect in the sialic acid biosynthesis). Both strains will be compared with wild-type animals. We plan to analyse O-GlcNAc, sialic acid, sialic acid binding proteins and sialic acid-dependent differentiation markers in all organs over the whole lifespan and quantify age-dependent muscle performance in vivo. The outcome of metabolic sialic acid engineering will be analysed in embryonic stem cells (differentiation) and neuronal cells (neurite outgrowth e.g. regeneration). We also plan to analyse the involvement of sialylation and O-GlcNAcylation on the function of endothelial cells. After metabolic engineering we will analyse their barrier capacity and age-related impact on neuronal cells by real-time cell analysis. Since high levels of glucose induce glycation of proteins, we will analyse the function of an artificial ...
The hemolymph of the Japanese beetle, Allomyrina dichotoma, contains a lectin with a specificity for β-D-galactose 1 . This lectin, which can be purified by affinity and ion-exchange chromatography, is composed of two isolectins, Allo A-I and Allo A-II. The material provided by EY Laboratories is a mixture of the two isolectins, with Allo A-II being the predominant isolectin. Allo A is active between pH 5-9. Allo A has a greater binding affinity for β-D-galactose than RCA-I and it does not bind to α-D-galactose 2. Immobilized Allo A-II binds most strongly with α2,6 sialylated complex-type oligosaccharides, but free N-acetylneuraminic acid up to 2M does not displace such glycoconjugates, nor does α2,3-link sialic acid react with the lectin 3 . In spleen cell activation studies the Allo A lectin has been shown to be as mitogenic as Con A and more mitogenic than PHA-L. In the production of Interleukin-2 (Il-2), at a concentration of 0.5 µg/ml, Allo A had higher Il-2 units production than Con ...
Variations of serum sialic acid level in liver cirrhosis. Saatea Arif, Najeeb-ul-Haq, Ruhila Hanif, A. Sattar Khan, Jamil-ur-Rehman, Taufeeq Ahmed Mufti. Comparison of students performance under composite scheme and split scheme of first professional MBBS. examination. Tehseen Iqbal, Naila Hamid, Hamid Javaid ...
In human serum, at least two molecular species of the neural cell adhesion molecule (NCAM) with molecular weights of 110,000-130,000 and 150,000-180,000, respectively, can be identified by Western blotting. Both are characterized by the absence of epitopes for monoclonal antibodies KD11 and MG5, which specifically recognize intracellular domains of the human NCAM transmembrane isoforms, NCAM-140 and NCAM-180. In contrast to the Mr 110,000-130,000 molecule also detectable in serum samples from healthy blood donors, the Mr 150,000-180,000 molecule appears to be tumor associated. The only difference between these two species is shown to be the presence of long chains of α-(2,8)-linked N-acetylneuraminic acids, which are characteristic for the so-called embryonic NCAM form. After treatment with endoneuraminidase N, the Mr 150,000-180,000 molecule can no longer be discriminated from the Mr 110,000-130,000 molecule in Western blotting as well as gel and anion exchange chromatography experiments. The ...
Langley, K. und Gratzl, Manfred (1991): Neural Cells adhesion Molecule NCAM in neural and endocrine cells. In: Gratzl, Manfred und Langley, K. (Hrsg.): Markers for Neural and Endocrine Cells : molecular and cell biology, diagnostic applications. Winheim: Wiley-VCH Verlag. S. 133-178 [PDF, 6MB] ...
Paper: Significance Of Serum Lipid Peroxides, Total And Lipid-Bound Sialic Acid As Markers For Liver Diseases , Author: Thanaa Hamed, Mahasen Abdel Sattar, Fauna Abd El- Salam*, Sherif Abou El Dahab**, and Amal Idris , Year: 2000 , Faculty of Medicine, Benha University
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Escherichia coli K1 strains are major causative agents of invasive disease of the new born. The age dependency of infection can be reproduced in the neonatal rat. Colonization of the small intestine following oral administration of K1 bacteria leads rapidly to invasion of the blood circulation; bacteria that avoid capture by the mesenteric lymphatic system and evade antibacterial mechanisms in the blood may disseminate to cause organ-specific infections such as meningitis. Some E. coli K1 surface constituents, in particular the polysialic acid capsule, are known to contribute to invasive potential but a comprehensive picture of the factors that determine the fully virulent phenotype has not so far emerged ...
Escherichia coli K1 strains are major causative agents of invasive disease of the new born. The age dependency of infection can be reproduced in the neonatal rat. Colonization of the small intestine following oral administration of K1 bacteria leads rapidly to invasion of the blood circulation; bacteria that avoid capture by the mesenteric lymphatic system and evade antibacterial mechanisms in the blood may disseminate to cause organ-specific infections such as meningitis. Some E. coli K1 surface constituents, in particular the polysialic acid capsule, are known to contribute to invasive potential but a comprehensive picture of the factors that determine the fully virulent phenotype has not so far emerged ...
Diabetes is estimated to affect over 25 million individuals in the U.S., and 285 million people worldwide," said Jane J. Kim, M.D., a -participating researcher from the Department of Pediatrics at the University of California, San Diego in La Jolla, CA. "Our study for the first time links human-specific sialic acid changes to insulin and glucose metabolism and therefore opens up a new perspective in understanding the causes of diabetes.". The researchers studied two groups of mice that lacked CMAH. They found they could not produce a type of sialic acid called NeuSGc. The second group of mice were normal. When the mice were given a high fat diet, leading them to become obese. Only the mice lacking the ability to produce sialic acid on the cell surface from absence of NeuSGc developed impaired insulin production.. Gerald Weissmann, M.D., Editor-in-Chief of the FASEB Journal wonders if humans lack the CMAH enzyme for a reason related to survival. Perhaps it is a defense against bacteria or ...
In N-acetylneuraminic acid, apart from O9 and O8, a possible glycosylation site is the O4 position. For example, gangliosides HLG-2 and HPG-7 are considered to be potential lead compounds for carbohydrate-based drug development to treat neural disorders. However, the construction of their α(1 → 4) fucosyl sialic acid and α(2 → 4) linkages between sialic acids is difficult because of the regioselec ...
Sialoglycoproteins: Glycoproteins which contain sialic acid as one of their carbohydrates. They are often found on or in the cell or tissue membranes and participate in a variety of biological activities.
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TY - JOUR. T1 - The genetically modified polysialylated form of neural cell adhesion molecule-positive cells for potential treatment of X-linked adrenoleukodystrophy. AU - Jang, Jiho. AU - Kim, Han Soo. AU - Kang, Joon Won. AU - Kang, Hoon Chul. PY - 2013/1. Y1 - 2013/1. N2 - Purpose: Cell transplantation of myelin-producing exogenous cells is being extensively explored as a means of remyelinating axons in X-linked adrenoleukodystrophy. We determined whether 3,3,5-Triiodo-L-thyronine (T3) overexpresses the ABCD2 gene in the polysialylated (PSA) form of neural cell adhesion molecule (NCAM)-positive cells and promotes cell proliferation and favors oligodendrocyte lineage differentiation. Materials and Methods: PSA-NCAM+ cells from newborn Sprague-Dawley rats were grown for five days on uncoated dishes in defined medium with or without supplementation of basic fibroblast growth factor (bFGF) and/or T3. Then, PSA-NCAM+ spheres were prepared in single cells and transferred to ...
Sialic acids are prominent termini of mammalian glycoconjugates and are key binding determinants for cell-cell recog-nition lectins. Binding of the sialic acid-dependent lectin, myelin-associated glycoprotein (MAG), to nerve cells is implicated in the inhibition of nerve regeneration after injury. Therefore, blocking MAG binding to nerve cell sialoglycoconjugates might enhance nerve regeneration. Previously, we reported that certain sialoglycoconjugates bearing N-acetylneuraminic acid (NeuAc) but not N-glycolylneuraminic acid (NeuGc) support MAG binding (Collins et al., 1997a). We now report highly efficient conversion of sialic acids on living neural cells from exclusively NeuAc to predominantly NeuGc using a novel synthetic metabolic precursor, N-glycolylmannosamine pentaacetate (Man-NGc-PA). When NG108-15 neuroblastoma-glioma hybrid cells, which normally express only NeuAc (and bind to MAG), were cultured in the presence of 1 mM ManNGcPA, they expressed 80-90% of their sialic acid precursor pool as
Linton, D, Karlyshev, A V, Hitchen, P G, Morris, H R, Dell, A, Gregson, N A and Wren, B W (2000) Multiple N-acetyl neuraminic acid synthetase (neuB) genes in Campylobacter jejuni: identification and characterization of the gene involved in sialylation of lipo-oligosaccharide. Molecular microbiology, 35(5), pp. 1120-1134. ISSN (print) 0950-382X ...
Abstract:Background: The metabolic syndrome comprises an array of cardiovascular disease (CVD) risk; the clustering of CVD risk factors in the metabolic syndrome suggests a common underlying mechanism. Circulating serum sialic acid, an inflammatory marker has recently been shown to be a strong predictor of cardiovascular mortality, and obesity-related diseases. Objective: is to study the relationship between serum total sialic acid and metabolic variables in type 2 diabetes with and without metabolic syndrome.Subject and Methods: One hundred type 2 diabetic mellitus patients (52 of them had metabolic syndrome and 48 without it) were recruited from the National Diabetic Center, Al-Mustansiriya University during the period from June 2011 to January 2012. One hundred apparently healthy control matched for age and sex were participated in this study. Fasting venous blood samples were collected from all participants, the level of HbA1c was estimated by high performance liquid chromatography. Total ...
Sialic acids are a family of acidic monosaccharides that typically reside as terminal moieties on N- and O-linked glycans. These sugars are actively involved in a plethora of biological phenomena, ranging from cell-cell adhesion and recognition, intracellular signalling events, pathogen attack, viral infection and inflammatory disease. In addition, many cancer-related antigens contain terminal sialic acids or altered sialylation patterns. The identification of sialic acid-specific antibodies is important in the fields of basic research and diagnostics. Therefore the primary objective of this thesis was the generation and characterisation of recombinant antisialic acid antibodies.A single-chain antibody fragment (scFv) library was constructed from a chicken that was immunised with a novel synthetic sialic acid protein-conjugate (Neu5Gchumanserum albumin). The scFv library was biopanned using a second novel sialoneoglycoconjugate(Neu5Gc-bovine serum albumin). Anti-sialic scFvs were isolated ...
Sialoglycoproteins (SGs) have been shown to be important in the enhancement of sensitivity to sialic acid-specific toxin from E. histolytica (Feingold et al. 1984). This toxin is known to induce fluid secretion in ligated intestinal loops of indomethacin-pretreated rats. Since SGs serve as receptors for the E. histolytica toxin, the pathogenesis of amebiasis could be preceded by an initial unmasking event of surface sialic acid by the parasites sialidase, followed by attachment of the toxin. Feingold et al. (1985) reported the isolation of two cytotoxic factors from E. histolytica trophozoites, one of which is sensitive to sialic acid levels above 5 mg/ml. Our observation could imply that, when such a threshold level of free liberated by sialidase is attained, it triggers the expression of PSL to hydrolyse the sialic acid to pyruvate and N-acetyl mannosamine. This biochemical event may promote the interaction of cytopathic factors with the receptor. Moreover, when Neu5Ac2,3-lac was incubated ...
Sialoglycoproteins (SGs) have been shown to be important in the enhancement of sensitivity to sialic acid-specific toxin from E. histolytica (Feingold et al. 1984). This toxin is known to induce fluid secretion in ligated intestinal loops of indomethacin-pretreated rats. Since SGs serve as receptors for the E. histolytica toxin, the pathogenesis of amebiasis could be preceded by an initial unmasking event of surface sialic acid by the parasites sialidase, followed by attachment of the toxin. Feingold et al. (1985) reported the isolation of two cytotoxic factors from E. histolytica trophozoites, one of which is sensitive to sialic acid levels above 5 mg/ml. Our observation could imply that, when such a threshold level of free liberated by sialidase is attained, it triggers the expression of PSL to hydrolyse the sialic acid to pyruvate and N-acetyl mannosamine. This biochemical event may promote the interaction of cytopathic factors with the receptor. Moreover, when Neu5Ac2,3-lac was incubated ...
Sialic acid is a molecule which is responsible for the net negative surface charge of platelets. We investigated the effect of sialic acid on fresh and cryopreserved platelets. Platelet samples were obtained by platelet apheresis from 8 healthy donors. Platelet suspensions with different sialic acid concentrations (0, 1, 2 and 4 mg/mL) were studied for ADP and ristocetin induced platelet aggregation, basal and ADP induced P-selectin and glycoprotein- Ib/IX expression. Then platelet samples were cryopreserved in 5% DMSO with or without 4 mg/mL sialic acid. After thawing, P-selectin expression was compared with the control group. Six samples were also washed after thawing and P-selectin expression was again compared to unwashed samples. Sialic acid suppressed ADP induced platelet aggregation and P-selectin expression in a dose dependent manner. In cryopreserved samples, P-selectin expression of 4 mg/mL sialic acid containing group was found significantly higher than the control group (p, 0.001). ...
TY - JOUR. T1 - GANGLIOSIDES OF HUMAN MYELIN. T2 - SIALOSYLGALACTOSYLCERAMIDE (G7) AS A MAJOR COMPONENT. AU - Ledeen, R. W.. AU - Yu, R. K.. AU - Eng, L. F.. PY - 1973/10. Y1 - 1973/10. N2 - Abstract- Gangliosides were isolated from purified human myelin in a yield of 62 μg of lipid‐bound sialic acid per 100 mg of dry myelin. Sialosylgalactosyl ceramide (G7) was found to be a major component of the ganglioside fraction, amounting to 15 per cent of the total sialic acid. It accounted for 10 per cent of lipid‐bound sialic acid in adult human white matter, making it the third most abundant ganglioside on a molar basis. These results were obtained with an improved method for isolating total gangliosides in high yield, by employing DEAE‐Sephadex column chromatography. Myelin from other mammalian species had considerably less G7, and there were also indications of maturational changes. Both 2‐hydroxy and unsubstituted fatty acids were components of the ceramide unit, in a ratio of 3:2, ...
Increased risk for chronic comorbid disorders in patients with inflammatory arthritis: a population based study. Ursum, Jennie; Nielen, Mark M. J.; Twisk, Jos W. R.; Peters, Mike J. L.; Schellevis, François G.; Nurmohamed, Michael T.; Korevaar, Joke C. // BMC Family Practice;2013, Vol. 14 Issue 1, p199 Background: Studies determining the development of a wide variety of different comorbid disorders in inflammatory arthritis (IA) patients are scarce, however, this knowledge could be helpful in optimising preventive care in IA patients. The aim of this study is to establish the risk that new... ...
The reaction of colloidal iron hydroxide (CIH) with acidic groups was applied for an ultra-structural study of the distribution of sulphuric acid monoesters and sialic acid in synaptic vesicles and external nerve ending membranes isolated from rat brain. At pH 1.7 CIH was precipitated as electron-dense granules with a uniform size of 6-7 nm specifically labelling the carboxyl group of sialic acid and the sulphate group of monoesters of sulphuric acid. The differentiation of these 2 groups was achieved by treatment with neuraminidase and methylation followed by saponification. After preincubation with neuraminidase, which released 90-100% of the sialic acid from the membranes of the synaptic vesicles and the nerve endings, the electron-dense deposits marked the reaction sites of sulphate with CIH. The sulphate groups which were present at a concentration of 2.3 and 2.2 µmol/mg protein for the synaptic vesicle and nerve ending membrane preparations, respectively, were rendered soluble as methyl ...
In this study, we investigated the use of metabolic oligosaccharide engineering and bio-orthogonal ligation reactions combined with lectin microarray and mass spectrometry to analyze sialoglycoproteins in the SW1990 human pancreatic cancer line. Specifically, cells were treated with the azido N-acetylmannosamine analog, 1,3,4-Bu3ManNAz, to label sialoglycoproteins with azide-modified sialic acids. The metabolically labeled sialoglyproteins were then biotinylated via the Staudinger ligation, and sialoglycopeptides containing azido-sialic acid glycans were immobilized to a solid support. The peptides linked to metabolically labeled sialylated glycans were then released from sialoglycopeptides and analyzed by mass spectrometry; in parallel, the glycans from azido-sialoglycoproteins were characterized by lectin microarrays. This method identified 75 unique N-glycosite-containing peptides from 55 different metabolically labeled sialoglycoproteins of which 42 were previously linked to cancer in the literature
The recent study follows the aim to develop a novel, biocompatible, and bioresorbable material for peripheral nerve tissue engineering based on polysialic acid (polySia), a homopolymer of alpha 2, 8-linked sialic acid residues. To reach this goal, at first protocols for efficient coating of cell culture surfaces with soluble polySia were established. In addition, primary cells of the central and peripheral nervous system such as neonatal and adult Schwann cells, neural progenitor cells, dorsal root ganglionic neurons and embryonic spinal motoneurons which are all possible candidates for reconstructive therapies were cultured on polySia substrates. Respective cell cultures were evaluated with regard to cell survival and cell proliferation. PolySia turned out to be stable under cell culture conditions. Induced degradation of PolySia and its degradation products had no negative effects on cell cultures. Furthermore, polySia used as a cell culture substrate revealed its compatibility for the chosen ...
Accepted name: N-acylneuraminate-9-phosphate synthase. Reaction: phosphoenolpyruvate + N-acyl-D-mannosamine 6-phosphate + H2O = N-acylneuraminate 9-phosphate + phosphate. For diagram of reaction click here and mechanism click here.. Other name(s): N-acetylneuraminate 9-phosphate lyase; N-acetylneuraminate 9-phosphate sialic acid 9-phosphate synthase; N-acetylneuraminate 9-phosphate synthetase; N-acylneuraminate-9-phosphate pyruvate-lyase (pyruvate-phosphorylating); sialic acid 9-phosphate synthetase. Systematic name: phosphoenolpyruvate:N-acyl-D-mannosamine-6-phosphate 1-(2-carboxy-2-oxoethyl)transferase. Comments: Acts on N-glycoloyl and N-acetyl-derivatives.. Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9031-58-7. References:. 1. Roseman, S., Jourdian, G.W., Watson, D. and Rood, R. Enzymatic synthesis of sialic acid 9-phosphates. Proc. Natl. Acad. Sci. USA 47 (1961) 958-961.. 2. Watson, D.R., Jourdian, G.W. and Roseman, S. The sialic acids. 8. Sialic acid ...