The binding of microorganisms to platelets is a critical step in the development of infective endocarditis. In Streptococcus gordonii, this binding is mediated in part by serine-rich repeat proteins, which interact directly with sialic acid residues located on GPIIb receptors in the platelet membrane. In this study, we found that S. gordonii DL1 strain binds to platelets through bridging between sialic acid residue of fibronectin and serine-rich repeat protein (Hsa). Pretreatment of fibronectin with sialidases specific for alpha(2-3)-linked sialic acids was shown to significantly inhibit binding of the DL1 strain and the binding region(BR) of Hsa protein. Similarly, pre-incubation of bacteria or BR of Hsa with alpha(2-3)-sialyl-N-acetyllactosamine blocked fibronectin binding in the DL1 strain, but not the M99 strain. Together, these data show that the alpha(2-3)-sialic acid residues of fibronectin play an important role in the binding of S. gordonii DL1 to fibronectin through interactions with the Hsa receptor. This interaction is thought to play an important role in the development of pathogenic endocarditis, and may represent an important therapeutic target for the treatment of infective endocarditis.
Bacteria ; Blood Platelets ; Endocarditis ; Etorphine ; Fibronectins* ; Membrane Glycoproteins* ; Membranes ; N-Acetylneuraminic Acid* ; Sialic Acids ; Streptococcus gordonii*

Neuraminidase (NA) cleaves the glycosidic bond linkages of sialic acids to release the mature virions from infected cells and has been an attractive therapeutic target for anti-influenza agents. In our ongoing investigation of NA inhibitors in mushroom extracts, we found that the extract the fruiting body of Glaziella splendens potently inhibited neuraminidase. The fruiting bodies of G. splendens were extracted and partitioned successively with hexane, ethyl acetate, and butanol. The ethyl acetate soluble-layer was subjected to silica gel and Sephadex LH-20 column chromatographies, and MPLC to obtain five compounds (1–5). Their structures were determined by spectroscopic methods. NA inhibitory activity of these compounds was evaluated using NAs from recombinant rvH1N1, H3N2, and H5N1 influenza A viruses. One compound (1) was elucidated as a new azaphilone derivative, and four compounds (2–5) were identified as entonaemin A, comazaphilone D, rubiginosin A, and entonaemin B, respectively. Compounds 3 and 4 showed considerable inhibitory activity against three types of neuraminidases with the IC₅₀ values of 30.9, 41.8, and 35.7 µM for 3 and 46.5, 50.4, and 29.9 µM for 4, respectively. This study reveals that the fruiting bodies of G. splendens possess azaphilone derivatives with the NA inhibitory activity. This is the first report on the isolation of neuraminidase inhibitors from the fruiting bodies of G. splendens.
Agaricales ; Chromatography ; Fruit ; Influenza A virus ; N-Acetylneuraminic Acid ; Neuraminidase ; Sialic Acids ; Silica Gel ; Virion

BACKGROUND: Sialic acid residues are known to play a key role in the normal function of the glycoconjugates. Recently, with the development of specific sialic acid binding lectins such as Maackia seed agglutinin(MAA) and Sambucus nigra agglutinin(SNA), it has made easier to localize the sialic acid residues by the histochemical staining methods. OBJECTIVES: We were to observe the expression of sialic acids according to the differentiation of cultured human nasal epithelial cells by the immunohistochemistry method using Wheat germ agglutinin(WGA), MAA, and SNA. MATERIALS AND METHODS: Human nasal epithelial cell culture was done as floating method for the induction of differentiation. The cultured cells were fixed with 2.5% glutaraldehyde and the epon 812 was used as embedding material. The immunohistochemistry was done as Lim's method. RESULTS: The WGA and MAA positive reactions were noted from the floating zero day through the fourteenth day. The reactions were positive to the squamous-like cells and differentiating cells(ciliated and secretory epithelial cells). The WGA binding patterns were homogeneous but MAA binding patterns were inhomogeneous. The SNA positive reaction was noted only in the fourteenth day and the reaction was inhomogeneous. These results meant that N-acetyl glucosamine and N-acetyl neuraminic acid(alpha 2,3) galactose were expressed from the floating zero day and N-acetyl neuraminic acid(alpha 2,6) galactose was expressed from the floating fourteenth day. CONCLUSION: N-acetyl neuraminic acid(alpha 2,3) galactose may be more important to the primary defence of human nasal epithelial cell. Due to the inhomogeneity of the reaction, the further study using Lowicryl K4M will be needed.
Cells, Cultured ; Epithelial Cells* ; Galactose ; Glucosamine ; Glutaral ; Glycoconjugates ; Humans* ; Immunohistochemistry ; Lectins ; Maackia ; N-Acetylneuraminic Acid* ; Sambucus nigra ; Sialic Acids* ; Triticum

Adamantane ; therapeutic use ; Amantadine ; therapeutic use ; Antiviral Agents ; therapeutic use ; Child ; Guanidines ; Humans ; Influenza, Human ; drug therapy ; prevention & control ; Pyrans ; Rimantadine ; therapeutic use ; Sialic Acids ; therapeutic use ; Zanamivir

OBJECTIVETo observe the change in the amount of sialic acids on hepatocellular carcinoma (HCC) cell membrane.

METHODSSurgical specimens of HCC and liver cirrhosis tissues were obtained from 28 patients to prepare carcinoma cell and hepatocyte suspensions by collagenase digestion. For assay of α2, 3 and α2, 6-sialic acids, the cells were suspended in the staining buffer containing either fluorescein isothiocyanate-Maackia amurensis lectin (FITC-MAL) or fluorescein isothiocyanate-Sambucus nigra bark lectin (FITC-SNA) and incubated for 1 h, respectively. Flow cytometric analysis was carried out to measure the mean fluorescence intensity (MFI) on the cell surface.

RESULTSIn both FITC-MAL- and FITC-SNA-incubated HCC cells, the MFI on the cell surface was greater than that of the hepatocytes.

CONCLUSIONBoth of α2, 3 and α2, 6- sialic acids increases significantly on the hepatocyte membrane after the carcinomatous change.

Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Membrane ; metabolism ; Humans ; Liver Cirrhosis ; metabolism ; pathology ; Liver Neoplasms ; metabolism ; pathology ; Sialic Acids ; metabolism

OBJECTIVETo observe the effect of different nutritional routes of giving nutrition on the intestinal mucus barrier in severely scalded rats.

METHODSWistar rats inflicted with 30% TBSA III degree scalding on the back were employed as the model and were randomly divided into 3 groups, i.e. control (C), parenteral nutrition (PN) and enteral nutrition (EN) groups. The rats in PN and EN groups were supplied with equal amount of nitrogen and calories and with equal volume of nutrition solution. The dynamic changes in the thickness of intestinal mucus layer and the contents of protein, hexose and acetylneuraminate in the mucus were examined.

RESULTSWhen compared with those in C group, the intestinal mucus layer became thinner and the contents of protein, hexose and acetylneuraminate in the mucus in both PN and EN groups decreased evidently after scalding. When compared between two nutritional groups, the thickness of intestinal mucus layer and the contents of the hexose and acetylneuraminate in the mucus in EN were much thicker and higher than those in PN group, while the mucus protein content exhibited no obvious difference between PN and EN groups.

CONCLUSIONIt was suggested that intestinal goblet cell synthesized and secreted less mucus after scalding in rats resulting in thinning of intestinal mucus layer and the change in mucus components. When compared with those in PN group, less injury to the intestinal goblet cells occurred and the intestinal mucus synthesis was less affected in EN group, and the components of intestinal mucus were maintained stable.

Animals ; Burns ; metabolism ; Enteral Nutrition ; Female ; Hexoses ; metabolism ; Intestinal Mucosa ; metabolism ; pathology ; Male ; Parenteral Nutrition ; Proteins ; metabolism ; Rats ; Rats, Wistar ; Sialic Acids ; metabolism ; Time Factors

Neural cell adhesion molecule (NCAM) is a glycoprotein expressing on the surface of neurons, glial cells, bone cells and natural killer cells. NCAM plays an important role in the process of cell - cell adhesion and cell migration, and is also a model protein to study polysialic acid. In this paper, NCAM gene from mouse mammary gland cells (NMuMG) was cloned into eukaryotic expression vectors pcDNA3.1(+) and transfected into mutant Chinese hamster ovary cells ldlD-14. The stable transfection over-expressing NCAM was obtained through the G418 selection and confirmed by Western blotting. Due to unique characters of ldlD-14 cells, carbohydrate chain of NCAM molecule can be easily manipulated with or without adding galactose in the serum free medium, and this modification can provide the basis for further studies on the effect of glycosylation on NCAM molecular function.
Animals ; CHO Cells ; Cloning, Molecular ; Cricetinae ; Cricetulus ; Female ; Galactose ; Glycosylation ; Mammary Glands, Animal ; cytology ; Mice ; Neural Cell Adhesion Molecules ; biosynthesis ; Polysaccharides ; chemistry ; Sialic Acids ; chemistry ; Transfection

OBJECTIVETo investigate the proliferation and plasticity of neural stem cells in situ in adult rats after cerebral infarction.

METHODSCerebral infarction models of rats were made and the dynamic expression of bromodeoxyuridine (BrdU) and BrdU/polysialylated neural cell adhesion molecule (PSA-NCAM) were determined by immunohistochemistry and immunofluorescence staining.

RESULTSCompared with the controls, the number of BrdU-positive cells in the subventricular zone (SVZ) and hippocampus increased strikingly at day 1 (P < 0.05), reached maximum at day 7, and decreased markedly at day 14, but it was still elevated compared with that of the controls (P < 0.05); The number of BrdU-labeled with PSA-NCAM-positive cells increased strikingly at day 7 (P < 0.05), reached maximum at day 14, and markedly decreased at day 28, but it was still elevated compared with that of the controls (P < 0.05), and was equal to 60% of the number of BrdU-positive cells in the same period.

CONCLUSIONSOur results indicate that cerebral infarction stimulate the proliferation of inherent neural stem cells in situ and most proliferated neural stem cells represent neural plasticity.

Animals ; Bromodeoxyuridine ; Cell Division ; Cerebral Infarction ; pathology ; Hippocampus ; pathology ; Male ; Neural Cell Adhesion Molecule L1 ; Neuronal Plasticity ; Neurons ; pathology ; Rats ; Rats, Wistar ; Sialic Acids ; Stem Cells ; pathology

In comparison with its counterpart from N. meningitides, all conserved motifs were found in the N-termini of E. coli CMP-NeuAc synthetase. E. coli CMP-NeuAc synthetase seems to have redundant C-termini with a less effect on its activity. To explain this speculation, a series of recombinant DNAs with deletion from 3'-end of CMP-NeuAc synthetase were produced by PCR, ligated into expression vector pET-15b and expressed in BL21(DE3)pLysS. After induction with IPTG, we found that the recombinant enzyme with deletion of 189 amino acids from C0termini retained its activity. This result demonstrates that the 229 amino acids of N-termini was the minimal functional domain of E. coli CMP-NeuAc synthetase. The deletions altered the optimum pH and thermostability of active truncated enzymes, indicating that the truncated C-terminal amino acids of E. coli CMP-NeuAc synthetase could affect the conformation of the enzymatic catalytic domain and therefore affect its catalytic activity and thermostability, although it is not involved in enzymatic activity directly.
Amino Acid Sequence ; Cytidine Monophosphate N-Acetylneuraminic Acid ; metabolism ; Enzyme Stability ; Escherichia coli ; enzymology ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; Mutation ; N-Acylneuraminate Cytidylyltransferase ; chemistry ; physiology ; Structure-Activity Relationship

Abnormal glycosylation due to dysregulated glycosyltransferases and glycosidases is a key phenomenon of many malignancies, including colorectal cancer (CRC). In particular, increased ST6 Gal I (beta-galactoside alpha 2, 6 sialyltransferase) and subsequently elevated levels of cell-surface alpha 2, 6-linked sialic acids have been associated with metastasis and therapeutic failure in CRC. As many CRC patients experience metastasis to the liver or lung and fail to respond to curative therapies, intensive research efforts have sought to identify the molecular changes underlying CRC metastasis. ST6 Gal I has been shown to facilitate CRC metastasis, and we believe that additional investigations into the involvement of ST6 Gal I in CRC could facilitate the development of new diagnostic and therapeutic targets. This review summarizes how ST6 Gal I has been implicated in the altered expression of sialylated glycoproteins, which have been linked to CRC metastasis, radioresistance, and chemoresistance.
Antigens, CD/*metabolism ; Colorectal Neoplasms/*metabolism/pathology/*therapy ; Drug Resistance, Neoplasm ; Glycoproteins/*metabolism ; Humans ; Liver Neoplasms/secondary ; Lung Neoplasms/secondary ; Radiation Tolerance ; Receptor, Epidermal Growth Factor/metabolism ; Sialic Acids/*metabolism ; Sialyltransferases/*metabolism