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G Uhlenbruck

Publications and source records attributed to G Uhlenbruck.

At least 19 recordsLinked to original sources
PubMed1992

A quantitative microassay of carbohydrate-mediated cell adhesion to glycoconjugates immobilized on polystyrene plates.

A microadhesion assay that allows the quantitative determination of carbohydrate-mediated cell adhesion to glycoconjugates immobilized on 96-well polystyrene plates has been developed. After dislodging nonadherent cells by centrifugation, specifically bound cells are quantified by colorimetric analysis of a blue formazan product generated from the dye 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide by enzymatic reduction. Carbohydrate specificity of the cell adhesion was demonstrated by inhibition analyses and the general applicability of the assay was proved with indicator cells of three different origins: mouse fibrosarcoma cells, Chang liver cells, and human breast carcinoma cells (MDA-MB 231).

Animals↗
PubMed1992

Blood group antigen expression in medullary carcinoma of the thyroid. An immunohistochemical study on the occurrence of type 1 chain-derived antigens.

Using monoclonal antibodies (MoABs) against blood group determinants and related carbohydrate sequences, it is now possible to clarify their carcinoma-associated modulation at a molecular level. In the present study a panel of MoABs against different type 1 chain derived blood group antigens, comprising A, B, H type 1, Le(a), sialyl-Le(a) (CA 19-9), sialyl type 1 structure (CA 50), and Le(b) was used to investigate their immunoreactivity in 38 medullary carcinomas of the thyroid (MTC) and in normal thyroid tissue. The antigens were not expressed in normal follicular or C-cells but were expressed to a various extent in MTC. The studies revealed some characteristic anomalies in the frequency and patterns of tumor-associated antigen expression. The MoAB C 50 stained 32 of the 38 tumors, H type 1 (Le(d)) was demonstrated in 21 and the Le(b) antigen in 27. The Le(a)- and the A antigen were detected in 10 and 12 tumors and the B antigen in one. From the results some rules about the pathways for tumor-associated re-expression of these antigens can be deduced. Le(a) antigen expression was significantly correlated with the CA 50 and Le(b) antigens. The significant relation observed between A-, H1-, and Le(b) antigen formation in MTC suggests the existence of a carcinoma-associated fucosyltransferase committing the type 1 precursor chain along the H1-antigen pathway, and by further glycosylation to an A-, B-, or a Le(b) antigen. Comparative studies of tumor-associated H type 1 and H type 2 antigen expression revealed that H type 2 antigen synthesis was significantly related to a blood type 0 in the host. On the other hand, H1 antigen reactivity was independent of the AB0 blood type of the hosts and was also detected in H type 2 antigen-negative tumors. These findings support the proposal that even in tumor tissue, H antigen expression is still determined by the interaction of at least two different genes. Despite the occurrence of the precursor substance (CA 50) and the formation of the Le(a)- and Le(b) antigens, indicating the presence of a alpha 1,4-fucosyl-transferase (Lewis-enzyme), only two tumors showed the formation of CA 19-9. In conclusion, the investigations demonstrated the dominant re-expression of three type 1 chain-derived structures in MTC, namely H type 1, Le(b), and CA 50. These findings support the general concept demonstrated in other carcinomas, that fucosyl- and sialyltransferases are preferentially activated in MTC.(ABSTRACT TRUNCATED AT 400 WORDS)

ABO Blood-Group System↗
PubMed1992

A novel galactose- and arabinose-specific lectin from the sponge Pellina semitubulosa: isolation, characterization and immunobiological properties.

A new lectin from the sponge Pellina semitubulosa is derived which was extracted and purified to homogeneity. The purified lectin is probably a hexamer of polypeptide chains (each M(r) 34,000) which are covalently linked via disulfide linkages; the isoelectric point is 6.1. The lectin displays the following specificities: D-galactose (50% inhibition of hemagglutination at 0.2 mM) = L-arabinose (0.2 mM) greater than D-fucose (1.5 mM) greater than D-glucose (3.0 mM). It precipitates human erythrocytes (A1, A2, A1B, B, and O) with a titer between 2(8) and 2(11) and erythrocytes from sheep and rabbits with a titer between 2(5) and 2(10). The Pellina lectin displays a strong mitogenic effect on spleen lymphocytes from mice. Immunochemical analyses revealed that both murine T- and B-lymphocytes display a capping of the lectin receptors on their cell surfaces after lectin treatment. Murine macrophages were found to endocytose the lectin. Pellina lectin at concentrations between 0.3 and 10.0 micrograms/ml potently enhances interleukin 1 (IL-1) release from mouse peritoneal macrophages and interleukin 2 (IL-2) production in mixed murine lymphocyte cultures.

Amino Acids↗
PubMed1992

Immunological and biological identification of tumour necrosis-like factor in sponges: endotoxin that mediates necrosis formation in xenografts.

Xenografts of the sponge Geodia cydonium in its closely related species G. rovinjensis resulted in a rapid rejection of the graft within a period of 5 days. We identified an immunoreactive tumour necrosis factor (TNF)-like activity in the xenograft (Mr of 30,000) two days after grafting. In-vivo injection of 5 micrograms human recombinant TNF-alpha induced cytotoxicity in sponge cells in the same pattern and time course as during natural xenograft rejection. Anti-TNF-alpha polyclonals were found to react with xenograft extracts, by Western blot analysis, as from day 2 after grafting. Using ELISA we detected the TNF-like activity from day 2 after grafting with peak levels at days 4 and 5, where the amount was 0.72 ng/micrograms tissue DNA. By day 1, gp27 (inhibitory aggregation factor) is already formed in the xenograft. In-vitro experiments on isolated G. cydonium cells showed that addition of purified gp27 induced the production of the TNF-like activity (up to 13.5 ng/ml). Evidence is presented that gp27 is a product of the gp180 lectin receptor. We conclude that gp27 induces TNF-like factor production, resulting in destruction and dissolution of the xenograft after 5 days.

Animals↗
PubMed1992

Monoclonal antibody FW6 generated against a mucin-carbohydrate of human amniotic fluid recognises a colonic tumour-associated epitope.

Mucus glycoproteins of human amniotic fluid were used to generate a monoclonal antibody (MAb) FW6, which stained the intestine of a 24 week stage fetus. In adults, 76% of colonic adenocarcinomas (13/17) showed strong expression of the FW6 epitope, but it was not detected in the histologically normal mucosae adjacent to the tumours or in normal left colon mucosa. In addition, MAb FW6 stained large cell carcinomas of the lung (2/3), gastric carcinomas (5/11), and ovary adenocarcinomas (3/4). The expression in carcinomas can also be called ectopic for testing normal tissues. MAb FW6 was also reactive with pyloric mucus glands, Brunner's glands of the duodenum, Paneth cells of the ileum, pancreatic ducts, absorptive cells of the right colon, bronchiolar glands, kidney urothelia, and with a restricted number of normal mucinous tubuli of salivary gland. It was demonstrated to be under the control of the secretion gene only in intestinal Paneth cells and absorptive cells of the right colon. Comparative histochemical analysis comprising a panel of MAbs suggests that the corresponding epitope of the MAb FW6 is a type II chain related carbohydrate structure belonging to the Lex/Ley-antigen family, but is different from short chain Lex and Ley.

Amniotic Fluid↗
PubMed1992

Invertebrate immunity: another viewpoint.

All vertebrates and invertebrates manifest self/non-self recognition. Any attempt to answer the question of adaptive significance of recognition must take into account the universality of receptor-mediated responses. These may take two forms: (1) rearranging, clonally distributed antigen-specific receptors that distinguish in the broadest sense between self and non-self, and non-self A from non-self B, latecomers on the evolutionary scene; (2) pattern recognition receptors, the earliest to evolve and still around, necessitating the requirement for induced second signals in T- and B-cell activation. Either strategy need not force upon invertebrates the organization, structure and adaptive functions of vertebrate immune systems. Thus, we can freely delve into the unique aspects of the primitive immune mechanisms of invertebrates. In contrast, using the opposite strategy which is still problematic, i.e. linking invertebrate and vertebrate defence, seems to give us an approach to universality that might eventually reveal homologous kinship.

Animals↗
PubMed1992

Inhibition of adhesion of S-fimbriated Escherichia coli to buccal epithelial cells by human milk fat globule membrane components: a novel aspect of the protective function of mucins in the nonimmunoglobulin fraction.

We investigated the presence of factors in human milk that inhibit invasion of pathogenic bacteria. The effect of human milk fat globule membrane (HMFGM) components on adhesion of cloned S-fimbriated Escherichia coli to human buccal epithelial cells was analyzed. S fimbriae are a common feature of E. coli strains causing sepsis and meningitis in newborns and are bound to epithelia via sialyl-(alpha-2-3)galactoside structures. Human milk fat globules (HMFG) could be agglutinated by the above-mentioned bacteria. Agglutination could be inhibited by fetuin, human glycophorin, and alpha 1-acid glycoprotein. In addition, pretreatment of HMFG with Vibrio cholerae neuraminidase markedly reduced bacterium-induced agglutinations, indicating the involvement of neuraminic acid-containing glycoproteins. In contrast, lipid droplets of infant formula or artificial lipid emulsions (Intralipid) could not be agglutinated. HMFG were present in stools of breast-fed neonates as shown by indirect immunofluorescence staining with a monoclonal antibody directed against carbohydrate residues present on HMFGM. These HMFG could be agglutinated by bacteria. HMFG inhibited E. coli adhesion to buccal epithelial cells. To further characterize relevant E. coli binding structures, HMFGM components were separated by gel chromatography. The mucin fraction showed the most pronounced inhibitory effect on adhesion of S-fimbriated E. coli to human buccal epithelial cells. Our data suggest that HMFG inhibit bacterial adhesion in the entire intestine and thereby may provide protection against bacterial infection.

Bacterial Adhesion↗
PubMed1992

The lectin from the algae Udotea petiolata: isolation, characterization and sugar binding properties.

In the present work, we describe a novel lectin which is specific for poly-N-acetyllactosamine sequences on complex N- and O-linked carbohydrate chains. This lectin was extracted and purified from the algae Udotea petiolata. The purified lectin is a monomer with a molecular mass of 65,000 and an isoelectric point of 5.6. It agglutinates normal, neuraminidase and protease-treated erythrocytes from humans irrespectively of the blood group (A, B and O) and animal erythrocytes. The Udotea lectin displays a strong mitogenic effect on human lymphocytes, especially T-cells. This lectin binds to the human serum plasma protein 8S alpha 3-glycoprotein with high affinity (ID50 0.02 microM); other species of human serum glycoproteins exhibiting a similar preponderance of complex type N-glycosylation showed also high binding capacities in the order 9.5 S alpha 1-glycoprotein greater than alpha 2-macroglobulin = beta 2 glycoprotein = immunoglobulin A greater than asialofetuin greater than alpha 1-acid glycoprotein and mucin glycopeptide (from amnion fluid). Monosaccharides and disaccharides tested do not bind to the lectin. This novel lectin will be useful for identification of N- and O-linked glycans rich in poly-N-acetyllactosamine.

Amino Acids↗
PubMed1991

Binding of cloned S-fimbriated E. coli to human buccal epithelial cells--different inhibition of binding by neonatal saliva and adult saliva.

Investigations were carried out on the adhesion of cloned S-fimbriated E. coli, labelled with fluoresceinisothiocyanate (FITC) to human buccal epithelial cells. Fluorescence microscopic analysis revealed binding of bacteria to 75-95% of epithelial cells. Inhibition experiments with fetuin, alpha 1-acid glycoprotein and N-acetyl neuraminic acid confirmed the specificity of bacterial binding to sialoglycoproteins. Further studies using saliva as an inhibitor resulted in a 4-5 times stronger binding inhibition by newborn saliva in comparison to adult saliva coinciding with a 4-5 times higher content of total N-acetyl neuraminic acid in samples of newborn saliva. In Western blot analysis sialoglycoprotein bands with a molecular weight greater than 200 kD reacting with wheat germ agglutinin (WGA), were only identified in samples of newborn saliva. These bands are classified as mucins on account of molecular weight and staining. These data suggest that saliva mucins could represent a major defense mechanism against bacterial infections at a stage of ontogeny where the secretory IgA-system is not yet developed.

Adult↗
PubMed1991

Can endurance sports stimulate immune mechanisms against cancer and metastasis?

Proceeding from a brief historical contemplation of the problematic nature of "exercise and malignancy" a training investigation (running on a treadmill) with animals is presented. By means of the experimental tumor model fibrosarcoma L-1 of BALB/c mice differences in growth, size, and metastatic spreading have been proven depending upon the mode and more significantly on the intensity of training and upon the mode of application and inoculation of tumor cells. Accordingly the best cancer protective effect could be observed when the animals performed a pre- and a post-running training before and after inoculation. More over mechanisms of the acute phase response of human athletes are discussed in relation to possible prophylactic effects on the prevention of infections and on the development of cancer.

Animals↗
PubMed1991

Analysis of pancreatic serum markers in patients with cystic fibrosis.

The occurrence of increased serum concentrations of pancreatic tumor markers CA 19-9, CA 50 and elastase 1 in cystic fibrosis (CF) prompted us to investigate the pancreatic markers DU-PAN-2 and TATI. DU-PAN-2 was measured in serum samples of 48 CF patients, 42 pediatric control patients, and 51 parents of CF children by a competition radioimmunoassay (RIA). A commercially available RIA test kit was used to measure TATI serum levels of 38 CF patients and 40 control patients. Nineteen percent of CF patients, 0% of the control group, and 6% of the parents exceeded the DU-PAN-2 threshold value of 300 U/ml. TATI concentrations were increased (greater than 20 micrograms/L) in 24% of CF patients and in 17% of control patients. The sensitivity-specificity curve of DU-PAN-2 was similar to those of CA 50 and elastase 1 but less discriminating than that of CA 19-9. However, the sensitivity-specificity profile of CA 19-9 can only be marginally enhanced in a range of low specificity by simultaneously determining elastase 1 and/or DU-PAN-2 antigens. TATI does not provide any diagnostic use in CF.

Adult↗
PubMed1991

Histochemical reactivity of the Geodia cydonium agglutinin (GCA) in human tissues.

We applied a peroxidase-antiperoxidase technique to study the distribution pattern and binding characteristics of the lectin from the marine sponge Geodia cydonium (Geodia cydonium agglutinin; GCA) in various human tissues. This lectin has been shown to possess a broad reactivity, but there was a distinct distribution of binding sites within the different organs. In the histochemical system GCA displayed no blood group specificity and labeled red blood cells, the vascular endothelium, and epithelial cells showing blood group antigen expression independent of the ABH blood group status. However, inhibition of GCA reactivity by simple sugars and complex carbohydrates demonstrated tissue-specific differences of lectin binding related to the ABH blood group status of the tissue and revealed information on the structural requirements of the histological lectin binding site. Tissues that totally lacked blood group antigens or that expressed only the H-antigen disclosed a GCA reactivity which was completely inhibited by lactose. In contrast, tissues that expressed blood group A- or blood group B-antigen exhibited a lactose-resistant lectin binding which was inhibited only by water-soluble blood group substance A from peptone A and by bovine glycophorin but not by other complex carbohydrates, including human glycophorin and human asialoglycophorin. Competitive inhibition studies in situ revealed that GCA binding was not inhibited by blood group type I/II carbohydrate sequence-specific lectins or by lectins with other sugar specificities. Inhibition by lactose of GCA binding to some histological sites indicates that the binding site consists of a beta-linked galactose-containing disaccharide. However, periodate oxidation of tissue sections had no effect on lectin binding, pointing to a subterminal location of the relevant sequence. The results obtained from inhibition studies with simple saccharides and complex carbohydrates in relation to the expression of ABH blood group antigens suggest a complex lectin combining site(s) in histological specimens. The lectin may possess either one binding site with a range of affinities for different carbohydrates (besides beta-linked disaccharides the GCA binding site accommodates to carbohydrate determinants carrying the blood group A or blood group B determinant), or may possess two different binding sites. Besides an acceptor site for beta-linked disaccharides, an additional binding site may exist accommodating to extended carbohydrate sequences related to A or B blood group structures. In conclusion, GCA represents a blood group-nonspecific lectin whose binding affinities are determined by the ABH blood group status of the tissue.

ABO Blood-Group System↗
PubMed1991

Antibodies against defined carbohydrate structures of Candida albicans protect H9 cells against infection with human immunodeficiency virus-1 in vitro.

In this study we raised antibodies against Candida albicans mannans of serotype A and B which comprise mannose alpha(1----2)-and mannose alpha(1----3)-linked residues. These antibodies inhibited human immunodeficiency virus type IIIB (HIV-IIIB) infection of H9 cells in vitro; 5 micrograms/ml of antibodies against mannan from serotype A and 10 micrograms/ml of antibodies against serotype B mannan were sufficient to inhibit infection by almost 100 and 85%, respectively, after an incubation period of 4 days. During a prolonged incubation period (8-12 days), the amount of HIV particles (as measured by reverse transcriptase activity in the culture medium) increased again in assays with antibodies raised against serotype B, but only little in assays containing antibodies against serotype A. Applying the Western blotting technique and a novel enzyme-linked immunosorbent assay system it was established that the antibodies reacted with the gp120 of HIV-1 exclusively. Immunofluorescence inspection using a confocal laser scanning microscope revealed that the gp120 protein is exposed on the outer surface of H9 cells where it is recognized by the anti-mannan antibodies. These results indicate that mannan residues of C. albicans can serve as antigens to raise neutralizing antibodies against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Structures of acidic O-linked polylactosaminoglycans on human skim milk mucins.

O-Linked glycans were isolated from human skim milk mucins or mucin-derived high-molecular weight glycopeptides and fractionated by anion exchange chromatography into neutral and acidic alditols. Major oligosaccharides contained in the acidic fraction were purified by high performance liquid chromatography and structurally characterized by a combination of fast atom bombardment mass spectrometry, methylation analysis and 500 MHz 1H-nuclear magnetic resonance spectroscopy. The structural aspects exhibited by these major species in the acidic fraction resemble those established previously for the neutral oligosaccharides from human skim milk mucins: 1) the size of the alditols varies from tri- to decasaccharides, 2) the core structure is of the ubiquitous type 2, 3) the backbone sequences are of the poly-N-acetyllactosamine type with a particular preponderance of linearly extended GlcNAc beta(1-3)Gal (major) or GlcNAc beta(1-6)Gal units (minor).

Amino Sugars↗
PubMed1990

Carbohydrate-mediated cell adhesion to glycoproteins immobilized on nitrocellulose.

A method that allows the estimation of carbohydrate-mediated cell adhesion to glycoproteins and polysaccharides immobilized to a nitrocellulose matrix is described. Specificity of adhesion by indicator cells (Chang liver) has been verified using glycoconjugates with defined carbohydrate structure. Two independent receptor systems with beta-galactose or alpha-fucose specificity, respectively, have been demonstrated by this method to occur on Chang liver cells. The method is also applicable for other indicator cells like murine fibrosarcoma cells and has been used for the analysis of dot-blots and Western blots of glycoproteins.

Animals↗
PubMed1990

Glycosphingolipid expression on murine L1-fibrosarcoma cells: analysis of clonal in vivo and in vitro selected sublines with different lung colonisation potential.

The patterns of acidic and neutral glycosphingolipids (GSLs) were examined in a syngeneic tumour system in Balb/c mice consisting of closely related cell lines with different colonisation potentials directed to the murine lungs (in vivo selected highly metastatic sublines of L1-fibrosarcoma cells and their WGA-resistant mutants with low metastatic potential). GSLs were analysed by high-performance thin-layer chromatography and structurally identified by fast atom bombardment mass spectrometry combined with compositional analyses and exo-glycosidase digestion. The results suggest that highly metastatic sublines L1-LM and L1-LM12 derived by in vivo selection from mouse fibrosarcoma cells (cell line L1) exhibit a drastic increase of polar ganglioside expression and a restriction to globo-series GSLs. Contrasting with this the low metastatic mutant cells (L1-LM13WGA) express a reduced portion of acidic GSLs and exhibit a shift to less polar ganglioside components. Total cellular and plasma membrane-integrated GSLs were demonstrated to exhibit largely identical patterns. Concomitant with a significant decrease in LacCer expression a substantial reduction of GM2 and a complete lack of GM3 expression can be assigned to the highly metastatic sublines of L1-cells. On the other hand, the more polar gangliosides GM1a and, to an even greater extent, GD1a (exceeding 70% of total gangliosides) accumulate on L1-LM and their clonal sublines. The shift to acidic GSLs of higher polarity is less pronounced on the low metastatic WGA-resistant mutant cells (L1-LM13WGA) showing a preponderance of GM1a. The portion of GD1a within the fractions of acidic GSLs does not correspond to the cellular activities of CMP-NeuAc/GM1 (alpha 2-3) sialyltransferase measured for high and low metastatic cell variants. Total sialic acid content of the various cell lines differs, but is not associated with the metastatic potential. Gangliosides on L1-cells exhibit a significant substitution of N-glycolyl for N-acetylneuraminic acid (13%) compared to their metastatic sublines and to mutant cells (less than 1%). A conversion of surface exposed GD1a to GM1a on membranes of metastatic cells by in situ treatment with Vibrio cholerae sialidase is associated with a significant reduction of tumour cell colonisation directed to the murine lungs.

Animals↗
PubMed1990

Polyclonal antibodies to mannan from yeast also recognize the carbohydrate structure of gp120 of the AIDS virus: an approach to raise neutralizing antibodies to HIV-1 infection in vitro.

This study initiates a new method of developing an antigen which might be useful in the prevention of HIV-1 infection. Using a mannan preparation from Saccharomyces cerevisiae neutralizing antiserum was raised in rabbits which prevents HIV-1 infection in vitro up to a titre of 1:128. The corresponding antibody preparation neutralized the in vitro infectivity down to a concentration of 5 micrograms/ml. Analytical studies suggest that the antibodies are directed against the mannose residues of the HIV-1 glycoprotein (gp) 120 and its precursor gp 160.

Acquired Immunodeficiency Syndrome↗