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  • 1
    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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  • 2
    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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  • 3
    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.
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  • 4
    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.
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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Glycoconjugate journal 1 (1984), S. 1-1 
    ISSN: 1573-4986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Glycoconjugate journal 1 (1984), S. 4-4 
    ISSN: 1573-4986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4986
    Keywords: lectins ; glycopeptides ; T-hapten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The specificity of severald-galactose-binding lectins including Agaricus bisporus (mushroom),Arachis hypogaea (peanut),Bauhinia purpurea andVicia graminea has been examined by inhibition of hemagglutination using a series of synthetic oligopeptides representing the N-terminal end of glycophorin A from N and M individuals, all carrying one or several disaccharide chains,d-Galβ1–3-d-GalNAcα-(T-hapten). Peanut lectin was inhibited by T-hapten-carrying glycopeptides, but the presence of a cluster of disaccharide chains had no effect on the lectin specificity. On the contrary, bothAgaricus bisporus andBauhinia purpurea lectins exhibited an enhanced reactivity with polyglycosylated peptides suggesting that their combining site might include two proximal galactose residues. All synthetic glycopeptides inhibitingVicia graminea lectin carry a cluster of T-disaccharide chains and the leucine residue at the N-terminal end, and the presence of a Glu residue at position 5 slightly increased the lectin activity. It is concluded that the binding ofVicia graminea is dependent upon a specific spatial conformation including a cluster of T-hapten chains in close vicinity of a hydrophobic surface represented by an appropriate N-terminal amino acid residue.
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  • 9
    ISSN: 1573-4986
    Keywords: extrahepatic biliary tract carcinoma ; gall bladder carcinoma ; T antigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The mucin-associated antigens Tn, sialosyl-Tn (STn), T and sialosyl-T (STAg) antigens accumulate through aberrant and incomplete glycosylation in malignant epithelial cells. Their diagnostic and prognostic significance in tumours of the colon and cervix has been described, and a possible role for Tn antigen in cell-to-cell adhesion has been suggested. These antigens have been demonstrated through peanut agglutinin (PNA) lectin binding and more recently using specific monoclonal antisera. Differences between the two methods have been described, which may be due to fixation schedules and/or specificity. We have investigated the effect of fixation on the binding of biotinylated PNA lectin and compared its reactivity with the immunoreactivity of monoclonal antisera to Tn, STn, T and STAg antigens in benign and malignant epithelium of the gall bladder, extrahepatic bile ducts and ampulla of Vater. We found that short-term fixation in formol sublimate resulted in poor PNA binding. All other tested fixation schedules showed strong perinuclear binding, similar to that found on cryostat sections. When compared with monoclonal antisera, PNA binding demonstrated the lowest specificity in benign epithelium. In both benign and malignant epithelium, the two methods cannot substitute for each other. STn and STAg antigens were found to be oncodevelopmental throughout the extrahepatic biliary tract. When used in a panel, they are useful as diagnostic markers of malignancy in gall bladder epithelium.
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  • 10
    ISSN: 1573-4986
    Keywords: anti-fucosylated antigen antibody ; colorectal cancer ; immunohistochemical diagnosis ; tumorassociated antigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A newly generated monoclonal antibody, YB-2, reacts simultaneously with Y (Fucα1→2Galβ1→4[Fucα1→3]GlcNAcβ), Leb (fucα1→2Galβ1→3[Fucα1→4]GlcNAcβ) and H type 2 (Fucα1→2Galβ1→4GlcNAcβ) antigens (Jpn J Cancer Res 1993: 84; 641-8). Since these antigens have been reported to be expressed strongly in malignant colorectal tissues, we investigated the usefulness of this antibody as an immunochemical tool for diagnosis of colorectal cancer. The rate of positive staining with YB-2 antibody in colorectal carcinoma (n=101), adenoma (n=26) and normal tissues (n=25) was 95.0, 50.0 and 12.0%, respectively. The specimens with negative staining were restricted in Dukes' A patients but 75% of Dukes' C patients were strongly positive. The intensity of positive staining with YB-2 antibody was also significantly related to the clinico-pathological features such as the depth of invasion, metastasis, histological types and tumor location. Moreover, the 5-year survival in patients whose tumors were positive with YB-2 antibody was found to be significantly low. Therefore, YB-2 antibody could be useful for immunodiagnosis and, possibly, immunotherapy of colorectal carcinoma.
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