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Sialic Acid (sialic + acid)
Kinds of Sialic Acid Terms modified by Sialic Acid Selected AbstractsTowards Selective Recognition of Sialic Acid Through Simultaneous Binding to Its cis -Diol and Carboxylate FunctionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2010Martín Regueiro-Figueroa Abstract A series of receptors containing phenylboronic acid and urea or thiourea units have been designed for simultaneous recognition of the cis -diol and carboxylate functions of sialic acids, which are known to be overexpressed on the surfaces of tumor cells. The interaction of the receptors with 5-acetylneuraminic acid (Neu5Ac) and 2-,- O -methyl Neu5Ac (MeNeu5Ac) in DMSO solution has been investigated bymeans of spectrophotometric titrations and 1H, 13C, and 11B NMR spectroscopy. Additionally, we have also investigated the binding of these receptors with competing monosaccharides such as D -(+)-glucose, D -fructose, methyl ,- D -galactoside, and methyl ,- D -mannoside. Our results show that 2-{[3-(4-nitrophenyl)thioureido]methyl}phenylboronic acid (3a) recognizes both Neu5Ac and MeNeu5Ac with good selectivity with regard to the remaining monosaccharides investigated. DFT calculations performed at the B3LYP/6-31G(d) level show that this selectivity is due to a cooperative two-site binding of Neu5Ac through 1) ester formation by interaction at the phenylboronic acid function of the receptor and 2) hydrogen-bond interaction between the thiourea moiety and the carboxylate group of Neu5Ac. Compound 3a can therefore be considered a promising synthon for the design of contrast agents for magnetic resonance imaging of tumors. In contrast, the analogue of 3a containing a urea moiety , compound 3b , displays strong binding to all monosaccharides investigated, due to two-site binding through interaction on the phenylboronic acid function of the receptor and a hydrogen-bond interaction between the urea moiety and the sugar hydroxy groups. [source] Serum Free Sialic Acid as a Marker of Alcohol AbuseALCOHOLISM, Issue 6 2007Lech Chrostek Background: Previous studies have shown that serum total sialic acid (TSA) concentration significantly increases during alcohol abuse. Chronic ethanol consumption impairs glycosylation of many proteins. The increased desialylation rate of serum glycoproteins is one of the effects of alcohol abuse. The aim of this study was to investigate the diagnostic value of free sialic acid (FSA) as a marker of alcohol abuse. Methods: We determined serum FSA concentrations in the group of 156 alcoholic subjects and 35 healthy control subjects by means of a modification of the thiobarbituric acid method. The alcoholic group was divided into subgroups according to their history of abuse. Results: The FSA concentration was significantly higher in alcoholic subjects than in healthy controls. The subjects who consumed alcohol for longer than a week showed significantly higher FSA level than those who consumed alcohol for a shorter period. The serum FSA concentration was significantly higher in alcoholic subjects with elevated markers of liver dysfunction. The diagnostic accuracy of FSA was high, although it did not differ from TSA, and was limited by its low sensitivity. Conclusions: This study shows that FSA concentration in the sera of alcoholic subjects is increased. The low diagnostic sensitivity is accompanied by high specificity, however the accuracy is high and similar to the accuracy of TSA. Free sialic acid does not seem to be a better marker of alcohol abuse than TSA and current markers. [source] Expression Of O-Acetyl Sialic Acid On Cerebral Microcirculation In A Glycine Or Taurine Treated Diabetic Rat ModelJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000A Noe Expression of sialic acid is altered in Diabetes mellitus. This modification has also been involved with both vascular and neurologic diseases, and with the increase of no enzymatic glycosylation of proteins. In our opinion, the lectins were very useful with specificity for sialic acids in order to determine the level of sialic acid expression on cerebral microcirculation in a diabetic Wistar rat model with streptozotocin. In this model, the glycine (1%) and taurine (0.5%) aminoacids were placed in drinking-water by six months. At the end of this time, the animals were sacrificed, their brains surgically removed and frozen in liquid nitrogen, and the specimens cut in serial sections. Immediately, the sections were incubated with different biotin-labelled lectins specific to sialic acid using peroxidase-labelled avidin as second ligand and H2O2 chromogen. The results showed greater O-acetyl sialic acid expression in cerebral capillaries of untreated diabetic rats than in glycine-, taurine-treated diabetic rats or than in control animals. The minor sialic acid expression may be an indicator of degenerative diseases such as Alzheimer's or the vascular disease of diabetic patients and probably is related to cellular protective properties of the glycine and taurine aminoacids. These first protective characteristics that have been observed in both ischemia with cellular ATP depletion models, suggest the utilization of aminoacids glycine or taurine in diabetic patient in order to avoid the development of microinfarcts. [source] Removal of lipopolysaccharide and reactive oxygen species using sialic acid immobilized polysulfone dialyzerPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009Jung-Jhih Chang Abstract Sialic acid (N -acetylneuraminic acid, NANA) was covalently immobilized onto the surface of a polysulfone (PSF) hollow fiber membrane. Prior to the immobilization, the surface of PSF was treated with ozone, followed by grafting with acrylic acid, and then the esterification of NANA. The surface concentration of NANA was determined by 2-thiobarbituric acid (TBA) test. Hemocompatibility, the capability of suppressing oxidative stress, and clearance of lipopolysaccharide (LPS) from the resulting hollow fiber membrane were evaluated. The results show that by immobilizing NANA onto PSF hollow fiber, the adhesion of platelet was reduced, while both APTT and PT were little affected. Furthermore, oxidative stress was suppressed by NANA-immobilized PSF hollow fibers. The level of LPS was also greatly reduced. Copyright © 2009 John Wiley & Sons, Ltd. [source] Prenatal diagnosis of free sialic acid storage disorders (SASD)PRENATAL DIAGNOSIS, Issue 8 2006Nina Aula Abstract Free sialic acid storage disorders, Salla disease (SD) and Infantile sialic acid storage disease (ISSD), are lysosomal storage diseases due to impaired function of a sialic acid transporter, sialin, at the lysosomal membrane. Several mutations of the sialin gene, SLC17A5, are known, leading either to the severe neonatal/infantile disease or to the milder, adult-type developmental disorder, Salla disease. Free sialic acid accumulation in lysosomes causes increased tissue concentration and consequently elevated urinary excretion. Prenatal diagnosis of SASD is possible either by determination of free sialic acid concentration or by mutation analysis of the SLC17A5 gene in fetal specimen, in chorionic villus biopsy particularly. Both techniques have been successfully applied in several cases, sialic acid assay more often in ISSD cases but mutation analysis preferentially in SD. Sialic acid assay of amniotic fluid supernatant or cultured amniotic fluid cells may give erroneous results and should not be used for prenatal diagnosis of these disorders. The present comments are mainly based on our experience of prenatal diagnosis of SD in Finnish families. A founder mutation in SLC17A5 gene, 115C-> T, represents 95% of the disease alleles in the Finnish SD patients, which provides a unique possibility to apply mutation analysis. Therefore, molecular studies have successfully been used in 17 families since the identification of the gene and the characterization of the SD mutations. Earlier, eight prenatal studies were performed by measuring the free sialic acid concentration in chorionic villus samples. Copyright © 2006 John Wiley & Sons, Ltd. [source] Enhancing glycoprotein sialylation by targeted gene silencing in mammalian cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2010Min Zhang Abstract Recombinant glycoproteins produced by mammalian cells represent an important category of therapeutic pharmaceuticals used in human health care. Of the numerous sugars moieties found in glycoproteins, the terminal sialic acid is considered particularly important. Sialic acid has been found to influence the solubility, thermal stability, resistance to protease attack, antigenicity, and specific activity of various glycoproteins. In mammalian cells, it is often desirable to maximize the final sialic acid content of a glycoprotein to ensure its quality and consistency as an effective pharmaceutical. In this study, CHO cells overexpressing recombinant human interferon gamma (hIFN,) were treated using short interfering RNA (siRNA) and short-hairpin RNA (shRNA) to reduce expression of two newly identified sialidase genes, Neu1 and Neu3. By knocking down expression of Neu3 we achieved a 98% reduction in sialidase function in CHO cells. The recombinant hIFN, was examined for sialic acid content that was found to be increased 33% and 26% respectively with samples from cell stationary phase and death phase as compared to control. Here, we demonstrate an effective targeted gene silencing strategy to enhance protein sialylation using RNA interference (RNAi) technology. Biotechnol. Bioeng. 2010;105: 1094,1105. © 2009 Wiley Periodicals, Inc. [source] Type 2 diabetes mellitus: a disease of the innate immune system?DIABETIC MEDICINE, Issue 3 2004An update Abstract A few years ago a hypothesis was proposed suggesting that elements of the innate immune system, such as acute phase reactants, contribute to the development of Type 2 diabetes mellitus. Acute phase reactants such as C-reactive protein and sialic acid may thus predict risk of developing Type 2 diabetes mellitus, as well as being markers of diabetes microvascular and macrovascular complications. This article discusses these issues. [source] Improved sample preparation method for glycan analysis of glycoproteins by CE-LIF and CE-MSELECTROPHORESIS, Issue 8 2010Zoltan Szabo Abstract CE is a high-resolution separation technique broadly used in the biotechnology industry for carbohydrate analysis. The standard sample preparation protocol for CE analysis of glycans released from glycoproteins generally requires derivatization times of overnight at 37°C, using ,100 fold excess of fluorophore reagent, 8-aminopyrene-1,3,6-trisulfonic-acid, if the sample is unknown, or it is a regulated biotherapeutic product, possibly containing terminal sialic acid(s). In this paper, we report on significant improvements for the standard CE sample preparation method of glycan analysis. By replacing the conventionally used acetic acid catalyst with citric acid, as low as 1:10 glycan to fluorophore molar ratio (versus the typical 1:,100 ratio) maintained the >95% derivatization yield at 55°C with only 50,min reaction time. Terminal sialic acid loss was negligible at 55°C during the derivatization process, and indicating that the kinetics of labeling at 55°C was faster than the loss of sialic acid from the glycan. The reduced relative level of 8-aminopyrene-1,3,6-trisulfonic-acid simplified the removal of excess reagent, important in both CE-LIF (electrokinetic injection bias) and CE-MS (ion suppression). Coupling CE- ESI-MS confirmed that the individual peaks separated by CE corresponded to single glycans and increased the confidence of structural assignment based on glucose unit values. [source] Measurement of electrophoretic mobility of cardiomyocytesELECTROPHORESIS, Issue 21 2009Ying Zhou Abstract The electrophoretic mobility (EPM) of rat cardiomyocytes with or without the treatment of neuraminidase was studied by cell electrophoresis. The EPM was found to change over a range from 0 to 8.67,,m,s,1/V,cm,1, depending on ionic strength, transmembrane potential, pH value, and/or surface charges. It is interesting that zero EPM was observed but reverse of the mobility was not. These results suggested that the negative charges carried on the cardiomyocyte surface might comprehensively consist of surface sialic acid, plasmalemma proteins, phospholipids, and transmembrane potential. The aberrant electrical double layer formed between the carried negative charges and adions had a big adsorption layer and a diffusion layer whose sizes changed circularly, making only negative charges be carried on the surface of living cardiomyocytes. The special structures on the surface of cardiomyocytes probably play a considerable role in the process of cardiac electrical activity. [source] Association of serum sialic acid and MMP-9 with lipids and inflammatory markersEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2 2000Kalela Background Inflammation of the arterial wall has emerged to be an important contributor to the process of atherosclerosis, the major cause of coronary heart disease. Several factors are currently under investigation as inflammatory markers of atherosclerosis. Serum sialic acid and matrix metalloproteinase-9 may provide such markers. We studied their association with the lipid profile and with the inflammatory markers C-reactive protein and leukocyte count in a clinically healthy population of men. Materials and methods Cardiovascular risk-related laboratory tests were carried out in 65 consecutive male employees in connection with an occupational health survey in 1996. The subjects were divided into tertiles on the basis of serum sialic acid or matrix metalloproteinase-9 concentration. Results In a stepwise polychotomous logistic regression model adjusting for coronary heart disease risk factors, serum sialic acid concentration was not associated with markers of inflammation but rather with the lipid risk factors of atherosclerosis: inversely with HDL cholesterol (OR = 0.081, 95% CI 0.0068,0.97) and positively with total cholesterol (OR = 2.4, 95% CI 1,5.6). Matrix metalloproteinase-9 levels had a significant positive correlation with the leukocyte count (OR = 2.3, 95% CI 1.4,4). Conclusions Serum sialic acid does not appear to be an indicator of inflammation but is somehow connected with the level of total and HDL cholesterol. Serum matrix metalloproteinase-9 may provide a useful marker of inflammation because it correlates with the leukocyte count and is not associated with the lipid profile. [source] Synthesis and Biological Evaluation of Non-Hydrolyzable 1,2,3-Triazole-Linked Sialic Acid Derivatives as Neuraminidase InhibitorsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2009Michel Weïwer Abstract ,-Sialic acid azide 1 has been used as a substrate for the efficient preparation of 1,2,3-triazole derivatives of sialic acid using the copper-catalyzed azide,alkyne Huisgen cycloaddition ("click chemistry"). Our approach is to generate non-natural N-glycosides of sialic acid that are resistant to neuraminidase-catalyzed hydrolysis as opposed to the natural O-glycosides. These N-glycosides would act as neuraminidase inhibitors to prevent the release of new virions. As a preliminary study, a small library of 1,2,3-triazole-linked sialic acid derivatives has been synthesized in 71,89,% yield. A disaccharide mimic of sialic acid has also been prepared using the ,-sialic acid azide 1 and a C-8 propargyl sialic acid acceptor in 68,% yield. A model sialic acid coated dendrimer was also synthesized from a perpropargylated pentaerythritol acceptor. These novel sialic acid derivatives were then evaluated as potential neuraminidase inhibitors using a 96-well plate fluorescence assay; micromolar IC50 values wereobserved, comparable to the known sialidase inhibitorNeu5Ac2en.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] An Acyclic Aminonaphthyridine-Based Receptor for Carbohydrate Recognition: Binding Studies in Competitive SolventsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2007Monika Mazik Abstract 1H NMR spectroscopic and microcalorimetric titrations revealed that receptor 3b, consisting of three protonated 2-amino-1,8-naphthyridine units, binds N -acetylneuraminic acid (Neu5Ac), the most commonly occurring sialic acid, with high affinity in competitive solvents such as water/dimethyl sulfoxide. Receptor 3b is able to form neutral/charge-reinforced hydrogen bonds and ion pairs with Neu5Ac, similar to sialic acid-binding proteins. Furthermore, indications for weak binding of neutral sugars, such as methyl ,- D -glucopyranoside, D -maltose and D -cellobiose were provided by NMR spectroscopy. Molecular modelling calculations, synthesis and binding studies in aqueous media are described. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The porcine trophoblastic interferon-,, secreted by a polarized epithelium, has specific structural and biochemical propertiesFEBS JOURNAL, Issue 11 2002Avrelija Cenci At the time of implantation in the maternal uterus, the trophectoderm of the pig blastocyst is the source of a massive secretion of interferon-gamma (IFN-,), together with lesser amounts of IFN-,, a unique species of type I IFN. This trophoblastic IFN-, (TrIFN-,) is an unprecedented example of IFN-, being produced spontaneously by an epithelium. We therefore studied some of its structural and biochemical properties, by comparison with pig IFN-, from other sources, either natural LeIFN-, (from adult leucocytes), or recombinant. Biologically active TrIFN-, is a dimeric molecule, of which monomers are mainly composed of a truncated polypeptide chain with two glycotypes, unlike LeIFN-, which is formed of at least two polypeptide chains and four glycotypes. TrIFN-, collected in the uterus lumen was enzymatically deglycosylated and analysed by mass spectrometry (MALDI-TOF). The data revealed that the more abundant polypeptide has a mass of 14.74 kDa, corresponding to a C-terminal cleavage of 17 residues from the expected 143-residue long mature sequence. A minor polypeptide, with a mass of 12.63 kDa, corresponds to a C-terminal truncation of 36 amino acids. MALDI-TOF analysis of tryptic peptides from the glycosylated molecule(s) identifies a single branched carbohydrate motif, with six N -acetylgalactosamines, and no sialic acid. The only glycan microheterogeneity seems to reside in the number of l -fucose residues (one to three). The lack of the C-terminal cluster of basic residues, and the presence of nonsialylated glycans, result in a very low net charge of TrIFN-, molecule. However, the 17-residue truncation does not affect the antiproliferative activity of TrIFN-, on different cells, among which is a porcine uterine epithelial cell line. It is suggested that these specific properties might confer on TrIFN-, a particular ability to invade the uterine mucosa and exert biological functions beyond the endometrial epithelium. [source] A carbohydrate neoepitope that is up-regulated on human mononuclear leucocytes by neuraminidase treatment or by cellular activationIMMUNOLOGY, Issue 2 2001Mark T. Quinn Summary The expression of cell-surface antigens can delineate specific leucocyte developmental or functional stages. For example, certain membrane glycoproteins are expressed selectively on leucocyte subsets only after activation. Leucocyte activation can also induce changes in carbohydrate epitopes expressed on surface antigens. In the present studies, we report on a novel monoclonal immunoglobulin M antibody (mAb 13.22) that recognizes a unique carbohydrate epitope expressed on human leucocyte membrane proteins. Characterization of mAb 13.22 specificity by immunoblotting showed that it recognized proteins of MW ,95 000 and 150 000, including both CD18 and CD11b. The mAb 13.22 epitope was removed by N -glycosidase F but not by endoglycosidase H or fucosidase, demonstrating that it is an N-linked carbohydrate antigen. Interestingly, immunoblot staining was enhanced after neuraminidase treatment, suggesting that the antibody epitope might also be partially masked by sialic acid. In resting leucocytes, the mAb 13.22 antigen was expressed strongly on neutrophils, while dull staining was present on monocytes, and no lymphocyte staining was observed. In marked contrast, treatment of leucocytes with neuraminidase resulted in exposure of a mAb 13.22 neoepitope on a subset of lymphocytes (primarily T lymphocytes and natural killer cells) as well as up-regulated staining more than 18-fold on monocytes. Activation of lymphocytes in culture with phytohaemagglutinin or concanavalin A also unmasked the mAb 13.22 neoepitope on ,37% of the CD45RO+ lymphocytes. Furthermore, analysis of leucocytes collected from the synovial fluid of patients with rheumatoid arthritis showed that ,18% of the lymphocytes present expressed the mAb 13.22 neoepitope. Taken together, our results suggest that the mAb 13.22 carbohydrate neoepitope could represent a physiologically relevant marker that is up-regulated on leucocyte subsets during the inflammatory response. [source] A miniaturized assay for influenza neuraminidase-inhibiting antibodies utilizing reverse genetics-derived antigensINFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 5 2009Matthew R. Sandbulte Background, Antibodies to neuraminidase (NA) contribute to protection during influenza virus infection, but NA inhibition (NI) titers are not routinely analyzed in vaccine trials. One reason is the cumbersome nature of the conventional thiobarbituric acid (TBA) NI assay, which uses chemical methods to quantify free sialic acid following incubation of NA with substrate in the presence of serum. In addition, the assay is complicated by the need to use virus of a hemagglutinin (HA) subtype novel to the host to detect NA-specific antibodies only. Objectives, Our primary objectives were to miniaturize the colorimetric NI assay to a format suitable for quantitative analysis of large numbers of samples, and validate the specificity and sensitivity of the miniaturized format with ferret and human sera. An additional aim was to use reverse genetics to construct HA-mismatched viral reagents bearing NA of recent influenza A vaccine strains and H6 HA. Results, Analysis of ferret antisera by the miniaturized assay demonstrated sensitivity and specificity comparable with the conventional assay. Similar increases in the NI titers in sera from vaccinated human volunteers were measured in miniaturized and conventional assays. Inactivated and live-attenuated vaccines increased NI titers against a given subtype at approximately the same rate. Conclusions, The reagents and miniaturized format of the TBA method described here provide a platform for practical serological monitoring of functional antibodies against NA. [source] Sialic acid tissue distribution and influenza virus tropismINFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 5 2008Urban Kumlin Abstract, Avian influenza A viruses exhibit a strong preference for using ,2,3-linked sialic acid as a receptor. Until recently, the presumed lack of this receptor in human airways was believed to constitute an efficient barrier to avian influenza A virus infection of humans. Recent zoonotic outbreaks of avian influenza A virus have triggered researchers to analyse tissue distribution of sialic acid in further detail. Here, we review and extend the current knowledge about sialic acid distribution in human tissues, and discuss viruses with ocular tropism and their preference for ,2,3-linked sialic acid. [source] Insulin resistance phenotypes and coronary artery disease in a native Pakistani cohortINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 5 2008A. S. Wierzbicki Summary Objective:, To determine the relationship between insulin resistance (IR) and atheroma burden in Pakistanis. Methods:, A prospective case,control study of 400 patients selected for the presence/absence of angiographic disease. Coronary atheroma burden was quantified and IR and cardiovascular risk factors were measured. Results:, The patients were divided into two groups by QuickI score. Waist circumference (90 ± 10 vs. 90 ± 9 cm; p = 0.7) was similar but the groups differed in body mass index (26.5 ± 3.7 vs. 24.2 ± 3.5 kg/m2; p < 0.001) and waist:hip ratio (0.94 ± 0.09 vs. 0.90 ± 0.06; p < 0.001). Lipid parameters showed similar high-density lipoprotein cholesterol (HDL-C) (0.77 ± 0.23 vs. 0.82 ± 0.22 mmol/l; p = 0.1) differences in triglycerides [1.32 (0.08,3.98) vs. 1.12 (0.37,3.61) mmol/l; p = 0.01], but no difference in low-density lipoprotein cholesterol (LDL-C) (2.75 ± 1.00 vs. 2.90 ± 0.94 mmol/l; p = 0.14). In insulin-resistant patients C-reactive protein (CRP) [6.8 (0.3,175.1) vs. 3.9 (0.2,57.9) mg/l: p < 0.001], sialic acid (82 ± 14 vs. 77 ± 15 mg/l; p < 0.001) aspartate transaminase [24 (7,171) vs. 21 (7,83) IU/l; p < 0.001] and gamma-glutamyl transferase [27 (8,482) vs. 21 (7,168) IU/l; p = 0.005] levels were increased. In insulin-resistant patients (n = 187), coronary artery disease (CAD) burden correlated (r = 0.55) with age (, = 1.62; p < 0.001), HDL-C (, = ,53.2; p < 0.001), lipoprotein (a) (, = 11.4; p = 0.007), smoking (, = 7.98; p = 0.004), CRP (, = 6.06; p = 0.03) and QuickI index (, = ,146; p = 0.04). In contrast in insulin-sensitive patients (n = 178) CAD burden (r = 0.46) correlated with LDL-C (, = 10.0; p = 0.02), CRP (, = 7.13; p = 0.03), HDL-C (, = ,38.1; p = 0.03), and weakly with age (, = 0.73; p = 0.07) and smoking (, = 5.52; p = 0.09). Conclusions:, Indian Asians show a dichotomous insulin-resistance phenotype. Atheroma is associated with low HDL-C and inflammation associated in all but LDL-C is a factor in the insulin sensitive in contrast to age and extent of IR in the insulin resistant. [source] Chronic alcohol consumption augments loss of sialic acid residues and alters erythrocyte membrane charge in type II diabetic patientsJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 5 2008Serkan Degirmenci Abstract In this study, the effects of alcohol consumption on erythrocyte membrane properties in type 2 diabetic patients were investigated. Therefore, we measured total and lipid-bound sialic acid (LSA) levels, sialidase activities, and erythrocyte membrane negative charge. Three groups, including control group (n = 20), alcohol-consuming diabetic patients group (n = 14), and diabetic patients without alcohol consumption group (n = 42), were created. Plasma total sialic acid (TSA) levels of the alcohol-consuming diabetic group were elevated as compared to the healthy control and diabetic group (p < 0.001 and p < 0.01, respectively). TSA levels of the diabetic group were significantly elevated as compared to the healthy control group (p > 0.001). Plasma LSA levels of the alcohol-consuming diabetic group were higher than that in the healthy control and diabetic group (p < 0.05 and p < 0.05, respectively). LSA levels of the diabetic group were found to be high as compared to the healthy control group (p < 0.05). Plasma sialidase activities of the alcohol-consuming diabetic group and diabetic group were significantly elevated as compared to the healthy control group (p < 0.05 and p < 0.05, respectively). Sialidase activities of the alcohol-consuming diabetic group were elevated as compared to the diabetic group, but this was not statistically significant (p > 0.05). Erythrocyte membrane negativity levels of the alcohol-consuming diabetic group and diabetic group were significantly decreased (p < 0.001 and p < 0.001, respectively) as compared to the healthy control group. Erythrocyte membrane negativity levels of the alcohol-consuming diabetic group were decreased as compared to the diabetic group, but this was not statistically significant (p > 0.05). In conclusion, our results indicate that chronic alcohol consumption may augment membrane alterations in type 2 diabetic patients. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:320,327, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20243 [source] Comparative study of total protein, and total and lipid-associated serum sialic acid levels in patients with type 2 diabetes mellitusJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2003Suat Ekin Abstract The aim of the present study was to investigate the serum total protein (TP), total sialic acid (TSA), lipid-associated sialic acid (LSA), LSA/TP, and LSA/TP values in type 2 diabetes mellitus (DM) patients. Two study groups (healthy controls and type 2 DM subjects) were examined. For the type 2 DM group, 120 patients (60 females and 60 males) who had been diagnosed and treated for type 2 DM in the Yuzuncu Yil University Hospital, Van, Turkey, were selected consecutively. Forty healthy individuals (20 females and 20 males) were selected from hospital staff and other outpatient clinics to serve as the control group. They were matched for age, sex, body mass index, and smoking status. None of the participants had taken vitamin or mineral supplements for at least 2 weeks before sampling. To determine serum glucose, TP, TSA, and LSA levels, blood samples were drawn after all of the subjects fasted overnight. It was found that diabetics had higher TSA, LSA, TSA/TP, and LSA/TP levels than controls. However, the TP levels were not significantly different between the groups. Our results showed that TSA, LSA, TSA/TP, and LSA/TP have interactive connections with DM. These parameters can be used as a diagnostic index for patients with DM. J. Clin. Lab. Anal. 17:124,126, 2003. © 2003 Wiley-Liss, Inc. [source] Increased sialylation of polymeric ,-IgA1 in patients with IgA nephropathyJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2002Joseph C.K. Leung Abstract The mechanism of mesangial IgA deposition is poorly understood in IgA nephropathy (IgAN). Abnormal glycosylation of carbohydrate moieties in the hinge region of the IgA molecule has recently attracted much attention. In this report, we studied galactosylation and sialylation profiles in ,- and ,-IgA1 from patients with IgAN. Total serum IgA1 was isolated from patients with IgAN or healthy controls by jacalin-affinity chromatography. Six fractions of molecular weight (MW) 50,1,000 kDa were separated by fast protein liquid chromatography (FPLC). Four lectin-binding assays were used to study the sialylation and the presence of terminal galactose or N-acetylgalactosamine (GalNAc) in the O-linked carbohydrate moieties of ,- or ,-IgA1. Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA) lectin recognize ,(2,3)- and ,(2,6)-linked sialic acid, respectively. Peanut agglutinin (PNA) and Helix aspersa (HA) lectin recognize terminal galactose and GalNAc, respectively. Reduced HA was demonstrated in macromolecular , or ,-IgA1 (300,825 kDa) isolated from patients with IgAN (P < 0.05 compared with healthy controls). Lambda- but not ,-IgA1 from patients with IgAN bound less to PNA (P < 0.05). The ,(2,3)-linked sialic acid content in ,- but not ,-IgA1 of MW 150,610 kDa from patients was higher than that of controls (P < 0.005). The ,(2,6)-linked sialic acid content in ,-IgA1 (300,825 kDa) and ,-IgA1 (150,610 kDa) from patients was also higher than that of controls. This unusual glycosylation and sialylation pattern of the ,-IgA1 may have important implications for the pathogenesis of IgAN, as both the masking effect of sialic acid on galactose and the reduced galactosylation will hinder the clearance of macromolecular ,-IgA1 by asialoglycoprotein receptor of hepatocytes. The negative charge from sialic acid may also favor mesangial deposition of macromolecular ,-IgA1 in IgAN. J. Clin. Lab. Anal. 16:11,19, 2002. © 2002 Wiley-Liss, Inc. [source] Relationships between Na+, K+ -ATPase, sialic acid content and fluidity in rainbow trout density-separated erythrocytesJOURNAL OF FISH BIOLOGY, Issue 2 2002E. Salvolini A correlation was found between membrane fluidity, sialic acid (SA) content and Na+, K+ -ATPase activity in the rainbow trout Oncorhynchus mykiss erythrocyte membrane and this suggests that alterations in erythrocyte Na+, K+ -ATPase activity might be caused by modified membrane fluidity through modified SA content. [source] Protective effect of glucosamine against ibuprofen-induced peptic ulcer in ratsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2007Sethumadhavan Santhosh Abstract Background:,Helicobacter pylori is the major causative factor of ulcer but the use of ibuprofen and other non-steroidal anti-inflammatory drugs have also been implicated in development of ulcer. The purpose of the present study was to determine the anti-ulcer effect of glucosamine. Methods:, The protective effect of glucosamine on ibuprofen-induced peptic ulcer in male albino rats was studied with respect to changes in the volume of gastric juice, acid output, pepsin activity, activities of membrane bound ATPases, protein content, glycoprotein components and histopathology. Results:, Oral administration of ibuprofen caused significant increase in the number of lesions in the gastric mucosa, increases in the volume of gastric juice and acidity, and decreased activity of pepsin. The levels of protein content and glycoprotein components (hexose, hexosamine and sialic acid) and ATPase activities were also observed. Oral pretreatment with glucosamine resulted in significant reduction in the number of lesions in the gastric mucosa and decreases in the volume of gastric juice and acidity. The pepsin activity was also maintained at near normalcy. Prior oral administration of glucosamine significantly prevented the ibuprofen-induced depletion of protein and glycoprotein components and maintained the activities of membrane bound ATPases as compared to untreated ulcer induced group of rats. Conclusion:, The anti-ulcerogenic activity of glucosamine might be ascribable to its ability to neutralize the hydrochloric acid secreted into the stomach and to its capability to strengthen the mucosal barrier by increasing mucosal glycoprotein synthesis and to its free radical scavenging property. Histopathological investigations of the mucosal tissue also support the anti-ulcerogenic effect of glucosamine. [source] Can glycans unveil the origin of glycoprotein hormones?,human chorionic gonadotrophin as an example,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2008R. Ramírez-Llanelis Abstract Doping with (glyco)protein hormones represent an extremely challenging, analytical problem as nearly all are constitutively present at low concentrations that fluctuate according to circadian or alternative periodical, or external stimuli. Thus the mere concentration in a biological sample is only resolutive when this surpasses extreme values. As the vast majority of these molecules are produced by recombinant DNA technology it is believed that the exogenous molecules could bear the signature of the host cell. In particular, these could comprise structural differences originated from co or post-translational differences. In this study we have employed both proteomics and glycomics strategies to compare recombinant and urinary human chorionic gonadotrophin in order to evaluate this hypothesis. As anticipated the recombinant hormone could be shown to contain N -glycolyl neuraminic acid, a sialic acid that cannot be produced by humans. Furthermore, differences were observed in the overall glycosylation, in particular the presence of abundant hybrid-type glycans that were much less pronounced in the recombinant species. These differences were determined to occur predominantly in the ,-subunit for which antidoping strategies focussed on these elements could be used for both chorionic gonadotrophin and lutrophin as they share the same ,-subunit. Copyright © 2008 John Wiley & Sons, Ltd. [source] A sialylation study of mouse brain gangliosides by MALDI a-TOF and o-TOF mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2008Mostafa Zarei Abstract Matrix-assisted laser desorption/ionization (MALDI) process of sialoglycoconjugates is generally accompanied by different levels of cleavage of sialic acid residues and/or by dehydration, and decarboxylation reactions. Quantitative densitometry of the mouse brain ganglioside (MBG) components separated by high-performance thin layer chromatography (HPTLC) and evidenced by orcinol staining was a basis to verify the ganglioside composition pattern with respect to the relative abundances of individual components in the mixture. A systematic mass spectrometry (MS) sialylation analysis has been carried out to evaluate the feasibility of an axial time-of-flight (a-TOF) MS, equipped with a vacuum MALDI source and an orthogonal-TOF (o-TOF) instrument with an ion source operated at about 1 mbar of N2. Besides, the esterification by one methyl group of the carboxyl group in sialic acid to increase the stability of the ganglioside species for MALDI MS analysis has been tested and the yield of intact ganglioside species and of the neutral loss of water and carbon dioxide estimated. For the sialylation analysis of native ganglioside mixtures the MALDI o-TOF analysis with 6-azo-2-thiothymine/diammonium citrate (ATT/DAC) as a matrix appears as an optimal approach for ganglioside profiling. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hyposialylation of neprilysin possibly affects its expression and enzymatic activity in hereditary inclusion-body myopathy muscleJOURNAL OF NEUROCHEMISTRY, Issue 3 2008Aldobrando Broccolini Abstract Autosomal recessive hereditary inclusion-body myopathy (h-IBM) is caused by mutations of the UDP- N -acetylglucosamine 2-epimerase/N -acetylmannosamine kinase gene, a rate-limiting enzyme in the sialic acid metabolic pathway. Previous studies have demonstrated an abnormal sialylation of glycoproteins in h-IBM. h-IBM muscle shows the abnormal accumulation of proteins including amyloid-, (A,). Neprilysin (NEP), a metallopeptidase that cleaves A,, is characterized by the presence of several N-glycosylation sites, and changes in these sugar moieties affect its stability and enzymatic activity. In the present study, we found that NEP is hyposialylated and its expression and enzymatic activity reduced in all h-IBM muscles analyzed. In vitro, the experimental removal of sialic acid by Vibrio Cholerae neuraminidase in cultured myotubes resulted in reduced expression of NEP. This was most likely because of a post-translational modification consisting in an abnormal sialylation of the protein that leads to its reduced stability. Moreover, treatment with Vibrio Cholerae neuraminidase was associated with an increased immunoreactivity for A, mainly in the form of distinct cytoplasmic foci within myotubes. We hypothesize that, in h-IBM muscle, hyposialylated NEP has a role in hampering the cellular A, clearing system, thus contributing to its abnormal accumulation within vulnerable fibers and possibly promoting muscle degeneration. [source] Increasing the sialylation of therapeutic glycoproteins: The potential of the sialic acid biosynthetic pathwayJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2009Kaya Bork Abstract The number of therapeutic proteins has increased dramatically over the past years and most of the therapeutic proteins in the market today are glycoproteins. Usually, recombinant glycoproteins are produced in mammalian cell lines, such as Chinese-hamster-ovary-cells to obtain mammalian-type of glycosylation. The terminal monosaccharide of N-linked complex glycans is typically occupied by sialic acid. Presence of this sialic acid affects absorption, serum half-life, and clearance from the serum, as well as the physical, chemical and immunogenic properties of the respective glycoprotein. From a manufacturing perspective, the degree of sialylation is crucial since sialylation varies the function of the product. In addition, insufficient or inconsistent sialylation is also a major problem for the process consistency. Sialylation of over-expressed glycoproteins in all mammalian cell lines commonly used in biotechnology for the production of therapeutic glycoproteins is incomplete and there is a need for strategies leading to homogenous, naturally sialylated glycoproteins. This review will shortly summarize the biosynthesis of sialic acids and describe some recent strategies to increase or modify sialylation of specific therapeutic glycoproteins. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3499,3508, 2009 [source] Serum Free Sialic Acid as a Marker of Alcohol AbuseALCOHOLISM, Issue 6 2007Lech Chrostek Background: Previous studies have shown that serum total sialic acid (TSA) concentration significantly increases during alcohol abuse. Chronic ethanol consumption impairs glycosylation of many proteins. The increased desialylation rate of serum glycoproteins is one of the effects of alcohol abuse. The aim of this study was to investigate the diagnostic value of free sialic acid (FSA) as a marker of alcohol abuse. Methods: We determined serum FSA concentrations in the group of 156 alcoholic subjects and 35 healthy control subjects by means of a modification of the thiobarbituric acid method. The alcoholic group was divided into subgroups according to their history of abuse. Results: The FSA concentration was significantly higher in alcoholic subjects than in healthy controls. The subjects who consumed alcohol for longer than a week showed significantly higher FSA level than those who consumed alcohol for a shorter period. The serum FSA concentration was significantly higher in alcoholic subjects with elevated markers of liver dysfunction. The diagnostic accuracy of FSA was high, although it did not differ from TSA, and was limited by its low sensitivity. Conclusions: This study shows that FSA concentration in the sera of alcoholic subjects is increased. The low diagnostic sensitivity is accompanied by high specificity, however the accuracy is high and similar to the accuracy of TSA. Free sialic acid does not seem to be a better marker of alcohol abuse than TSA and current markers. [source] Expression Of O-Acetyl Sialic Acid On Cerebral Microcirculation In A Glycine Or Taurine Treated Diabetic Rat ModelJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000A Noe Expression of sialic acid is altered in Diabetes mellitus. This modification has also been involved with both vascular and neurologic diseases, and with the increase of no enzymatic glycosylation of proteins. In our opinion, the lectins were very useful with specificity for sialic acids in order to determine the level of sialic acid expression on cerebral microcirculation in a diabetic Wistar rat model with streptozotocin. In this model, the glycine (1%) and taurine (0.5%) aminoacids were placed in drinking-water by six months. At the end of this time, the animals were sacrificed, their brains surgically removed and frozen in liquid nitrogen, and the specimens cut in serial sections. Immediately, the sections were incubated with different biotin-labelled lectins specific to sialic acid using peroxidase-labelled avidin as second ligand and H2O2 chromogen. The results showed greater O-acetyl sialic acid expression in cerebral capillaries of untreated diabetic rats than in glycine-, taurine-treated diabetic rats or than in control animals. The minor sialic acid expression may be an indicator of degenerative diseases such as Alzheimer's or the vascular disease of diabetic patients and probably is related to cellular protective properties of the glycine and taurine aminoacids. These first protective characteristics that have been observed in both ischemia with cellular ATP depletion models, suggest the utilization of aminoacids glycine or taurine in diabetic patient in order to avoid the development of microinfarcts. [source] NMR analysis of novel ganglioside GM4 analogues containing de- N -acetyl and lactamized sialic acid: probes for searching new ligand structures for human L-selectinMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2002Toshiyuki Hamada Abstract Detailed analysis of the 1H and 13C NMR spectra of two novel ganglioside GM4 analogues de- N -acetyl sialyl GM4 (1) and cyclic sialyl GM4 (2), which contain de- N -acetyl and lactamized sialic acid, respectively, instead of the usual N -acetylneuraminic acid, was carried out. The combination of NMR data, such as cyclization shifts, coupling pattern, intraresidual NOEs and the appearance of NH proton, provided the 5, 2B conformation for 2. Moreover, the conformation of a glycosidic bond connecting the Neu and Gal residues was determined by some interresidual NOEs in both 1 and 2. Copyright © 2002 John Wiley & Sons, Ltd. [source] In vitro fermentability of human milk oligosaccharides by several strains of bifidobacteriaMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 11 2007Robert E. Ward Abstract This study was conducted to investigate the catabolism and fermentation of human milk oligosaccharides (HMO) by individual strains of bifidobacteria. Oligosaccharides were isolated from a pooled sample of human milk using solid-phase extraction, and then added to a growth medium as the sole source of fermentable carbohydrate. Of five strains of bifidobacteria tested (Bifidobacterium longum biovar infantis, Bifidobacterium bifidum, Bifidobacterium longum biovar longum, Bifidobacterium breve, and Bifidobacterium adolescentis), B. longum bv. infantis grew better, achieving triple the cell density then the other strains. B. bifidum did not reach a high cell density, yet generated free sialic acid, fucose and N-acetylglucosamine in the media, suggesting some capacity for HMO degradation. Thin layer chromatography profiles of spent fermentation broth suggests substantial degradation of oligosaccharides by B. longum bv. infantis, moderate degradation by B. bifidum and little degradation by other strains. While all strains were able to individually ferment two monosaccharide constituents of HMO, glucose and galactose, only B. longum bv. infantis and B. breve were able to ferment glucosamine, fucose and sialic acid. These results suggest that as a potential prebiotic, HMO may selectively promote the growth of certain bifidobacteria strains, and their catabolism may result in free monosaccharides in the colonic lumen. [source] | ||||||||||||||||||||||||||||||||||