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  • 1
    Keywords: APOPTOSIS ; CELLS ; EXPRESSION ; GROWTH ; tumor ; BLOOD ; CELL ; Germany ; human ; cell line ; LINES ; FLOW ; CELL-LINES ; LINKAGE ; bone marrow ; BONE-MARROW ; ACID ; GLYCOPROTEIN ; ASSAY ; CELL-LINE ; leukemia ; LINE ; EXTRACELLULAR-MATRIX ; SURFACE ; ADHESION ; CLASS-I ; sialic acid ; PROGENITOR CELLS ; SIALIC-ACID ; LIVE CELLS ; DE-NOVO ; CELL-SURFACE ; HEMATOPOIETIC PROGENITOR CELLS ; PERIPHERAL-BLOOD ; PNA ; MATRIX ; PROGRAM ; RESIDUES ; SURFACE GLYCOPROTEIN ; extracellular matrix ; regulation ; GLYCOPROTEINS ; SIALOGLYCANS ; CD34 progenitor ; ecto-sialyltransferase ST6GaI 1 ; hematopoietic precursor cells ; HUMAN HEMATOPOIETIC PROGENITORS ; lactosamine ; surface sialylation
    Abstract: Surface expressed negatively charged sialoglycans contribute to the regulation of adhesive cellular interactions and are thus involved in the growth and differentiaton of hematopoietic progenitor cells. In particular, the cell surface sialylation state may govern the liberation of CD34+ hematopoietic precursors from bone marrow stroma cells and extracellular matrix. In order to assess the overall surface sialylation of live human CD34+ hematopoietic precursor cells, we applied a previously described flow cytometric enzyme assay. Cells with and without sialidase pretreatment were incubated in the presence of fluorescent CMP-sialic acid and exogenous ST6GalI. Thus sialylation of surface-expressed lactosamine residues was analysed. We demonstrated that surface lactosamines of CD34+ precursors derived from bone marrow and peripheral blood are over 95% sialylated, predominantly in alpha2-6 linkage. These results are in accordance with flow cytometric analysis of surface lectin staining. Sialic acid specific lectins MAA and SNA were strongly bound whereas SBA, VVA, and PNA became reactive only after sialidase pretreatment. CD34+ leukemia cell lines TF1 and KG1a also showed a high degree of surface sialylation, whereas cell line KG1 expressed to the largest extent free lactosamines. In these cell lines, alpha2-6 and alpha2-3 sialylated residues were present in equal amounts. In a variation of the flow cytometric enzyme assay, live cells were incubated without exogenous STGal I to measure the activity of endogenous ecto-sialyltransferase. Ecto sialyltransferase activity was observed in all CD34+ cells which was able to resialylate major surface glycoproteins such as HLA Class I, CD45, CD43, and CD34. The ecto-sialyltransferase may serve to maintain or increase surface sialylation rapidly without de novo synthesis
    Type of Publication: Journal article published
    PubMed ID: 15750786
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  • 2
    Keywords: APOPTOSIS ; CELLS ; EXPRESSION ; IN-VITRO ; proliferation ; tumor ; BLOOD ; CELL ; Germany ; human ; KINASE ; TYROSINE KINASE ; VITRO ; SYSTEM ; POPULATION ; DISTINCT ; MOLECULES ; TISSUE ; ACTIVATION ; MARKER ; CONTRAST ; T cell ; T cells ; T-CELL ; T-CELLS ; signal transduction ; VARIANTS ; MOLECULE ; antibodies ; LYMPHOCYTES ; B-CELLS ; MIGRATION ; O-acetylated sialic acid ; T-LYMPHOCYTES ; LIPID RAFTS ; CELL-SURFACE ; PERIPHERAL-BLOOD ; T lymphocytes ; PROGRAM ; RE ; VARIANT ; MEDIATED APOPTOSIS ; O-ACETYLATION ; function ; GANGLIOSIDE ; B-CELL ; peripheral blood ; CELL ANTIGEN RECEPTOR ; CDW60 ; germinal center ; SIALIC ACIDS
    Abstract: The disialoganglioside GD3 (CD60 a) and its O-acetylated variants have previously been described as surface molecules of human T lymphocytes of the peripheral blood system. Here we report the expression of the 9-O-, and 7-O-acetylated disialoglycans of GD3 (CD60 b and CD60 c respectively) on human tonsillar lymphocytes. CD60 b and c are surface-expressed on activated germinal centre B cells and colocalize in raft-like structures on the cell surface together with the cytoplasmic tyrosine kinase Lyn and Syk. Addition of CD60 b and c mAb together with anti-IgM/IL-4 to in vitro cultivated tonsillar B cells resulted in a costimulatory effect. During spontaneous and staurosporine-induced apoptosis a distinct population of activated annexin V+/CD60 b+/CD60 c- B cells was observed. CD60 b and c are also found on cells of the extrafollicular T cell area. On tonsillar T cells, CD60 b mAb had a costimulatory effect together with PHA while CD60 c mAb alone was sufficient to induce proliferation. In further contrast to B cells, during apoptosis a distinct CD60 b+ T cell subpopulation was not observed. Together, surface-expressed CD60 b and c are differently expressed on tonsillar B and T cells and may be involved in the regulation of activation and apoptosis of lymphocytes in secondary lymphatic tissue
    Type of Publication: Journal article published
    PubMed ID: 17115281
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  • 3
    Keywords: CELLS ; GROWTH ; PROTEIN ; COMPLEXES ; BINDING ; treatment ; PATTERNS ; ADHESION ; molecular modelling ; PLASMODIUM-FALCIPARUM ; POLYSACCHARIDES ; CONTINUOUS CULTURE ; CYTOADHERENCE ; HUMAN PLACENTA ; PARASITIZED ERYTHROCYTES ; Plasmodium falciparum ; CHONDROITIN SULFATE ; PROTEOGLYCANS ; FALCIPARUM-INFECTED ERYTHROCYTES ; pregnancy associated malaria ; COMPLEMENT ; cellulose sulfate ; complement system ; sulfated polysaccharides
    Abstract: Adhesion of Plasmodium falciparum infected erythrocytes (IE) to placental chondroitin-4-sulfate (CSA) has been linked to the severe disease outcome of pregnancy-associated malaria. Consequently, sulfated polysaccharides with inhibitory capacity may be considered for therapeutic strategies as anti-adhesive drugs. During in vitro screening a regioselectively modified cellulose sulfate (CS10) was selected as prime candidate for further investigations because it was able to inhibit adhesion to CSA expressed on CHO cells and placental tissue, to de-adhere already bound infected erythrocytes, and to bind to infected erythrocytes. Similar to the undersulfated placental CSA preferred by placental-binding infected erythrocytes, CS10 is characterized by a clustered sulfate pattern along the polymer chain. In further evaluation of its effects on P. falciparum interactions with host erythrocytes, we now show that CS10 inhibits the in vitro asexual growth of parasites in erythrocytes. Furthermore, we show that CS10 interferes with C1 of the classical complement pathway but not with MBL of the lectin pathway. In order to gain insights into the possible interactions of CS10 with known parasite receptors at the molecular level, we designed 3D-structures of characteristic stretches of CS10. CS10 fragments with clustered sulfate groups showed complex patterns of hydrophobic and hydrophilic patches most likely suitable for interactions with protein binding partners. The significance of CS10 interactions with the complement system as well as its anti-malarial effect for prospective drug application are discussed
    Type of Publication: Journal article published
    PubMed ID: 17115275
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  • 4
    Keywords: Germany ; BIOLOGY ; MOLECULAR-BIOLOGY ; NETHERLANDS ; molecular biology ; molecular
    Type of Publication: Journal article published
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  • 5
    Keywords: PEPTIDE ; APOPTOSIS ; CANCER ; CANCER CELLS ; CELLS ; EXPRESSION ; GROWTH ; tumor ; CELL ; CELL LUNG-CANCER ; Germany ; GENERATION ; INFORMATION ; NETWORK ; SITE ; SITES ; DISTINCT ; GENE ; GENE-EXPRESSION ; TUMORS ; COMPLEX ; COMPLEXES ; FAMILY ; INDUCTION ; colon ; MEMBER ; MEMBERS ; SEQUENCE ; VARIANTS ; ACID ; ISOFORM ; ISOFORMS ; PROGRESSION ; gene expression ; resistance ; MARKERS ; CANCER-CELLS ; COLON-CANCER ; SURFACE ; PHENOTYPE ; RT-PCR ; NETHERLANDS ; INDIVIDUALS ; tumor marker ; CELL-SURFACE ; BEHAVIOR ; INSIGHTS ; alternative splicing ; ANIMAL LECTINS ; apoptosis,galectin,invasion,metastasis,tumor diagnosis,tumor marker ; BLOOD-GROUP ANTIGEN ; CARBOHYDRATE-BINDING PROTEINS ; ENDOGENOUS LECTINS ; EOSINOPHIL CHEMOATTRACTANT ; GALACTOSIDE-SPECIFIC LECTINS ; MAMMALIAN GALECTINS ; MONOCLONAL-ANTIBODY PO66 ; SUGAR CODE
    Abstract: beta-Galactosides of cell surface glycoconjugates are docking sites for endogenous lectins of the galectin family. In cancer cells, primarily galectins-1 and -3 have been studied to date. With the emergence of insights into their role in growth control, resistance to or induction of apoptosis and invasive behavior the notion is supported that they can be considered as functional tumor markers. In principle, the same might hold true for the other members of the galectin family. But their expression in tumors has hitherto been a subject of attention only to a very limited extent. Pursuing our concept to define the complexity of the galectin network in cancer cells and the degree of functional overlap/divergence with diagnostic/therapeutic implications, we have introduced comprehensive RT-PCR monitoring to map their galectin gene expression. The data on so far less appreciated galectins in this context such as galectins-4 and -8 vindicate this approach. They, too, attach value to extend the immunohistochemical panel accordingly. Our initial histopathological and cell biological studies, for example on colon cancer progression, prove the merit of this procedure. Aside from the detection of gene expression profiles by RT-PCR, the detailed molecular biological monitoring yielded further important information. We describe different levels of regulation of galectin production in colon cancer cells in the cases of the tandem-repeat-type galectins-8 and -9. Isoforms for them are present with insertions into the peptide linker sequence attributed to alternative splicing. Furthermore, variants with distinct amino acid substitutions (galectin-8, Po66-CBP, PCTA-1, CocaI/II and galectin-9/ecalectin) and generation of multiple mRNA species, notably those coding for truncated galectin-8 and -9 versions with only one lectin site, justify to portray these two family members not as distinct individuals but as groups. In aggregate, the ongoing work to thoroughly chart the galectin network and to disentangle the individual functional contributions is expected to make its mark on our understanding of the malignant phenotype in certain tumor types
    Type of Publication: Journal article published
    PubMed ID: 15115907
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  • 6
    ISSN: 1573-4986
    Keywords: acute-phase proteins ; disease ; glycosylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pathophysiological variations in different glycoforms of acute-phase glycoproteins in serum most likely result from changes in the glycosylation process during their biosynthesis in the parenchymal cells of the liver. Biosynthesis in other cells or tissues may contribute, but in general appears to play a minor role. Inflammatory cytokines appear to regulate the process, but glycosylation changes are independent of protein synthesis. In addition, other humoral factors such as corticosteroids and growth factors are involved. The interplay of these factors is determined by the stage of the disease (e.g rheumatoid arthritis), the physiological situation (e.g. pregnancy), or directly or indirectly by extraneous factors such as drugs (e.g. ethanol). Information about the functional implications of the changes is limited, but some reports suggest that for α1-acid glycoprotein the changes might affect the operation of the immune system.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-4986
    Keywords: cell culture ; epitectin ; mucin-type glycoprotein ; nude mice ; tumorigenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Epitectin is a high molecular weight mucin-type glycoprotein over-expressed on the surface of human carcinoma cells. In cancer cells, it is proposed to play a protective function and to modulate cell surface properties such as antigenicity and cell adhesion. We have examined the effect of long-term culture on the cell curface expression of epitectin by a human laryngeal carcinoma cell line and the correlation between epitectin expression and tumor production in athymic mice. Indirect immunofluorescence labelling using an epitectin specific monoclonal antibody showed that the level of epitectin on the cell surface was significantly reduced after 78 or more generations in culture. Gel electrophoresis of cell extracts, followed by wheat germ agglutinin and peanut agglutinin overlay analyses, demonstrated similar losses in total cellular epitectin as a result of prolonged passage in culture. The levels of other glycoproteins reacting with wheat germ agglutinin were not significantly altered in high passage cells. Similar results were obtained when HMFG-2 monoclonal antibody was used to probe the levels of cell surface epitectin. In contrast to the above probes, the binding of HMFG-2 to epitectin is independent of glycosylation, therefore it can be concluded that the observed changes are not due to aberration in epitectin glycosylation with increasing passage number but rather due to lack of synthesis of epitectin. The ability of the low epitectin producing H.Ep.2 cells to grow as tumors in athymic mice was reduced compared to the high epitectin producing cells.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4986
    Keywords: affinity electrophoresis ; Aleuria aurantia lectin ; concanavalin A ; lectins ; sialyl-Lewis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract During acute inflammation, human α1-acid glycoprotein (AGP) is subject to marked changes in branching of its glycans, its degree of fucosylation and the expression of sialyl-Lewisx)(SLex) groups. To be able to study these changes in glycosylation in more detail, a procedure was developed to isolate the different glycoforms of AGP in milligram amounts by preparative affinity electrophoresis (AE) with a free lectin as fractionating agent. The method was applied to isolate differently fucosylated forms of AGP with the fucose-specific lectinAleuria aurantia (AAL). AGP was separated into one non-reactive (AO) and four reactive (A1-A4) fractions. It was found that, in particular, the highly fucosylated fractions A3 and A4 contained the inflammation-induced SLex groups of AGP. Analysis by crossed affinoimmunoelectrophoresis (CAIE) with concanavalin A (Con A) of these different glycoforms of AGP showed that the presence of tri-and/or tetraantennary glycans, instead of diantennary glycans, was associated with a higher degree of fucosylation. Identical results were obtained by subjecting Con A-fractionated forms of AGP to CAIE with AAL as the affinocomponent. It is expected that this method of preparative AE can generally be applied to other glycoproteins, which can be separated in different glycoforms by CAIE using lectins.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4986
    Keywords: advanced glycosylation end products ; aging ; complications ; diabetes ; elastin ; non-enzymatic glycation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Non-enzymatic glycation of proteins is one of the key mechanisms in the pathogenesis of diabetic complications and may be significant in the age-related changes of tissues. We investigated thein vitro glycation of human aortic α-elastin, and chose and adapted methods for evaluating the degree and kinetics of glycation. α-Elastin was prepared from thoracic aortas of young accident victims and glycated by incubating with different glucose concentrations (25, 50, 75 and 100 mmol/l) in 0.2 M phosphate buffer, pH 7.8 for 30 days, at 37°C. The degree of glycation was measured by three colorimetric methods,i.e. Nitroblue tetrazolium, 2-thiobarbituric acid and hydrazine; by aminophenyl-boronate affinity chromatography which determines Amadori products; and by a fluorescence method which determines advanced glycosylation end products. The highest degree of glycation was found on day 3 after the beginning of incubation. Fluorescence, as an index of advanced glycation, consistently increased from days 5 to 24. Investigation of the properties of glycated elastin may help in understanding the importance of this long-lived protein for the age-related changes in tissues and for diabetic complications.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Glycoconjugate journal 1 (1994), S. 75-75 
    ISSN: 1573-4986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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