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Biomedical subjects

H Wiegandt

Publications and source records attributed to H Wiegandt.

At least 55 records · Page 3Linked to original sources
PubMed1990

Immunochemical analysis of a monoclonal antibody recognizing a terminal glucuronic acid-containing epitope of insect acidic glycolipids.

A cloned, hybridoma cell-line was established that secreted the monoclonal antibody CAF-I following stimulation of the donor Balb/c mouse spleen cells by the total acidic fraction glycolipids of the third-instar larvae of Calliphora vicina (Insecta:Diptera). The monoclonal antibody isotype was IgG3 By qualitative (TLC-immunostaining) and semi-quantitative (enzyme-linked immunosorbent assay) methods, and comparison with the cross-reactivity of known monoclonal antibodies, the epitope was specifically located on the terminal, non-reducing end of the oligosaccharide chain of most of the insect acidic glycolipids. Following isolation of the two main acidic glycolipids of C. vicina larvae (A5c and Az5c), exoglycosidase treatment characterized the terminal disaccharide CAF-I epitope as glucuronic acid bound to subterminal galactose, both in the beta-anomeric configuration: G1cA beta-Ga1 beta-. The immunohistological distribution of this epitope in the dipteran, Drosophila melanogaster, showed its main expression to be in the imaginal discs and brain of the third-instar larva, and the retinula cells of the ommatidial elements of the compound eye retina of the adult female.

Animals↗
PubMed1989

Monoclonal antibodies against epitopes on ganglioside GD2 and its lactones. Markers for gliomas and neuroblastomas.

Monoclonal antibodies (mAbs) BW 625 and BW 704, of the IgG3 isotype, bound to immunochemically indistinguishable epitopes on ganglioside II3(Neu-Ac)2-GgOse3-Cer. Despite this fact the mAbs showed a differential binding pattern on human glioma cell lines i.e. immunohistochemical data indicate that the detected epitopes are not identical. Furthermore, either mAb is able to mediate the antibody-dependent cellular cytotoxicity reaction (ADCC) and the human-complement-dependent cytotoxicity reaction (CDC) with epitope-expressing tumor cells. All cryopreserved tissue specimens from gliomas and neuroblastomas were immunohistochemically stained, whereas the other small round cell tumors of childhood, as well as melanomas and small-cell lung carcinomas, were essentially negative. Positive staining of normal cryopreserved tissues was restricted to amyelinic axons, Hassal's bodies and some connective tissue fibers in thymus and the tegumentary epithelium of skin. The high selectivity of mAb BW 704 for gliomas and neuroblastomas, the lack of cross-reactivity with major tissues and the strong ADCC and CDC potential argue for the use of mAb BW 704 in immunotherapy of neuroblastomas and gliomas.

Antibodies, Monoclonal↗
PubMed1988

Melanoma-associated gangliosides in the fish genus Xiphophorus.

Gangliosides from benign and malignant melanomas and from normal skin of the fish genus Xiphophorus were isolated and analyzed by thin-layer chromatography. Individual ganglioside components were characterized by mapping according to their sialic acid content and by cleavage with neuraminidases. In all three tissues examined, sulfatide and the gangliosides NeuAc-GalCer (GM4), II3NeuAc-LacCer (GM3), II3NeuAc-GgOse3Cer (GM2), and II3(NeuAc)2-LacCer (GD3) were found. Ganglioside GD3 yielded a positive reaction, following immunoadsorption with mouse monoclonal antibody R24 on thin-layer plates. Two alkali-labile disialoganglioside species were specifically recognized by mouse monoclonal antibody D1.1, thus indicating the presence of O-acetyl-neuraminic acid residues. One of them, a major ganglioside component of the malignant melanoma, was identified as O-acetyl-GD3, since it could be converted to the R24-positive GD3 ganglioside after alkaline saponification. The other one appears to be restricted to the malignant tumor and represents a novel melanoma-associated ganglioside derivative. It was characterized as O-acetyl(NeuAc)2-nLc4Cer by exoglycosidase cleavage, by proving its neutral carbohydrate backbone as type II-chain lacto-series oligosaccharide using mouse monoclonal antibody 1B2, and by its cross-reaction with antibody R24 following alkaline treatment. Using antibody R24 and cryopreserved tissue sections of both benign and malignant amelanotic melanomas from albino fishes, it was demonstrated that one of the main melanoma-associated gangliosides, GD3, was exposed predominantly in the malignant tumor. Thus, the chemical nature and even the immunohistochemical localization of the gangliosides in fish melanomas proved to be very similar to those of the known gangliosides in the phylogenetically distant human melanomas.

Animals↗
PubMed1988

Promotion of survival and neurite outgrowth of cultured peripheral neurons by exogenous lipids and detergents.

Gangliosides, in particular the monosialoglycosphingolipids Gtet 1 (GM1), have previously been implicated in the mediation of neuronal rescue and restitutional axonal growth, both in vitro and subsequent to brain and peripheral nerve lesions. In the present study it is shown that the bis-sialosyl gangliosides Gtet2b and Gtet3b, but not the gangliosides Gtet2a and Gtet1, promote the survival of dissociated dorsal root ganglion (DRG) neurons cultured from Embryonic Day (E) 8 chicks (DRG8) almost to the same extent as nerve growth factor (NGF). Ciliary ganglion (CG) neurons from E8 chicks (CG8) and DRG10 neurons were virtually not supported suggesting considerable specificity in terms of neuronal targets and developmental stages being addressed. Moreover, a variety of other lipids including cerebroside (Cb), dipalmitoylphosphatidylcholine (DPPC) and -serine (DPPS), sulfatide (Sf), and sphingomyelin (Sm) were tested for putative survival promoting activity toward chick CG, DRG, and lumbar sympathetic ganglion (SG11) neurons. At the highest concentration employed (2.5 x 10(-5) M), Sm, DPPC, and DPPS maintained between 45 and 65% of the plateau survival with CG8 (maximally supported by ciliary neuronotrophic factor (CNTF], DRG8, and DRG10 neurons, and 30 to 40% with SG11 neurons. Cb supported CG8 neurons at about 55% of the plateau value achieved with CNTF, but had hardly any effect on the other neuron populations tested. Control experiments using highly enriched neurons and serum-free conditions assured that the effects were unlikely to be mediated by serum components or nonneuronal cells. A variety of detergents, in particular Triton X-100, also promoted the survival of CG8 and DRG10 neurons. Ganglioside Gtet1, Sm, and Triton X-100 shifted the NGF titration curve for DRG10 neurons between 6- and 15-fold in a dose-dependent manner suggesting synergisms between NGF and lipids for neuronal maintenance. These results document the neuronotrophic potency of certain gangliosides, a heterogeneous group of structurally unrelated lipids, and detergents. The mechanisms by which these agents modulate neuronal survival still await clarification.

Animals↗
PubMed1988

Detection of the L2/HNK-1 carbohydrate epitope on glycoproteins and acidic glycolipids of the insect Calliphora vicina.

The same or a very similar carbohydrate determinant, as represented by some sulfated, glucuronic acid-containing glycosphingolipids of human peripheral nerve, occurs on several adhesion molecules in the mammalian nervous system. In the present study, the occurrence of this epitope on glycoproteins and glycolipids of the fly, Calliphora vicina, was investigated by Western blot analysis and thin-layer chromatogram immunostaining. Several monoclonal antibodies recognizing an epitope on various neural cell adhesion molecules, designated L2 (334, 336, 349, and 412); the monoclonal antibody HNK-1 (recognizing an epitope on human natural killer cells); and a human IgM M-protein were found to react by Western blot analysis with various glycoproteins from larval and adult brains, although the intensity of staining of bands recognized by each antibody varied. Acidic glycolipids from pupae were also recognized, but only by the L2 antibody 334 and IgM M-protein. After desulfation of the acidic glycolipid fraction, the immunostaining pattern remained the same, an observation suggesting that the L2/HNK-1 epitope on insect acidic glycolipids contains a nonsulfated, glucuronic acid moiety. These observations indicate that the L2/HNK-1 carbohydrate structure occurs not only in vertebrates but also in insects on both glycoproteins and glycolipids, a finding suggesting a high degree of phylogenetic stability of this functionally important carbohydrate.

Animals↗
PubMed1987

Retinoic acid alters the metabolic 3H-labelling of glycosphingolipids.

Retinoic acid increases the incorporation of radioactivity from a mixture of [3H]-galactose and [3H]-glucosamine into glycosphingolipids of serum-starved quiescent human foreskin fibroblasts with a preferential labelling of ceramide mono- and dihexoside as compared to ceramide tri- and tetrahexoside. Under the conditions used, no similar change in the specific labelling of glycoprotein is observed. Alteration in [3H]-precursor uptake into glycolipids comparable to that seen under the influence of retinoic acid does not occur in the presence of phorbolester, colchicine, butyrate or after infection with cytomegalovirus.

Butyrates↗
PubMed1987

Carbohydrate analysis of chicken heart glycolipids.

Neutral and acidic glycolipids were extracted from chicken hearts. The neutral and acidic compounds were separated by preparative thin-layer chromatography into eight and two fractions, respectively. Total hydrolysis by mineral acid, permethylation analysis, and sequential cleavage with exoglycosidases showed the presence of glycolipids that belong to the globo- and gala-oligosaccharide series, i.e., the monohexosylceramides Glc-Cer and Gal-Cer, the dihexosylceramides Gal beta 1-4Glc-Cer and Gal alpha 1-4Gal-Cer, the tetrahexosylceramides GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-Cer and GalNAc alpha 1-3GalNAc beta 1-3Gal alpha 1-4Gal-Cer (III3GalNAc alpha-Ga3Cer) and four subfractions of the Forssman glycolipid GalNAc alpha 1-3GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-Cer. With the notable exception of III3GalNAc alpha 1-Ga3Cer, all glycolipids with terminal GalNAc alpha 1-3GalNAc1 reacted on thin-layer chromatograms with a monoclonal anti-Forssman antibody. The major components of the acidic fraction glycolipids were characterized as the lactose-based gangliosides Glac1 (GM3) and Glac2 (GD3).

Animals↗
PubMed1987

Glycosphingolipid composition of human semen.

Glycosphingolipids were extracted from human semen and purified. Based on the fluorometric assay of sphingosine, in spermatozoa a content of 4.4 +/- 0.9 nmol/10(8) cells of gangliosides and 22.1 +/- 1.7 nmol/10(8) cells of neutral glycosphingolipids was determined. Seminal plasma contained 4.1 +/- 0.6 nmol gangliosides and 29.3 +/- 1.5 nmol neutral glycosphingolipids per milliliter. The glycosphingolipid component patterns of human spermatozoa and seminal plasma were determined by thin-layer chromatography. Four neutral glycolipids were isolated and their carbohydrate moieties were characterized. All of these glycolipid components belonged to the globo-series. Gas chromatography, combined gas chromatography/mass fragmentography, and exoglycosidase treatments revealed the following structures for the glycosphingolipids of human semen: Glc1-Cer, Gal beta 1-4Glc1-Cer, Gal alpha 1-4Gal beta 1-4Glc1-Cer, and Gal-NAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc1-Cer. In addition, the occurrence of trace amounts of lactoneotetraosyl- and lactoneohexaosylceramide was detected by immunostaining after thin-layer chromatographic separation. Human spermatozoa, as well as seminal plasma, contained the gangliosides Glac1,Glac2, a sialolactoneotetraosylceramide, and a sialolactoneohexaosylceramide. The gangliosides were identified on the basis of their running characteristics by high-performance thin-layer chromatography, exoglycosidase treatment, and immunostaining after thin-layer chromatography. The ceramide composition of the glycolipids in human spermatozoa, as well as in seminal plasma, was dominated by C22:0-behenic acid and the saturated sphingoid d18:0, sphinganine.

Chromatography, Ion Exchange↗
PubMed1986

Glycosphingolipid biosynthesis in early chick embryos.

Early chick embryos at the age of 22 h (neurula stage) and 48 h (20-25 somite stage) were explanted from eggs and cultured in vitro in the presence of radioactive sugar precursors. Metabolically labelled glycosphingolipids were isolated. Amongst these, neutral and acidic components, the latter including sulfatide and gangliosides, were identified. Cleavage by exoglycosidases, as well as immunostaining with antibodies on thin-layer plates, showed that at both embryonic stages glycosphingolipids were synthesized that belong to the globo series (globoside, Forssman glycolipid), the lacto series (lactoneotetraosylceramide, nLc4Cer, and two nLc4Cer-based gangliosides, a monosialo and a disialo species), and the ganglio series (ganglioside Gtet1a and higher sialylated derivatives).

Animals↗
PubMed1986

A 500-MHz 1H-n.m.r. study of oligosaccharides derived from gangliosides by ozonolysis-alkaline fragmentation.

The structural-reporter-group resonances in the 1H-n.m.r. spectra of a series of ganglioside-derived oligosaccharides are completely assigned. The three different types of sialic acid residues which may occur in these compounds could be adequately characterized. They are distinguishable on the basis of the set of chemical shifts of their H-3a and H-3e atoms. The mutual influence of GalNAc beta-(1----4) and Neu5Ac alpha-(2----3), both linked to the same Gal residue, on the 1H-n.m.r. parameters of each other, reflects a well-defined solution conformation, which is held to be responsible for the resistance of this "internal" sialic acid towards various sialidases.

Animals↗
PubMed1986

Thin layer chromatography overlay technique in the analysis of the binding of the solubilized protoxin of Bacillus thuringiensis var. kurstaki to an insect glycosphingolipid of known structure.

The hypothesis tested was that a particular glycoconjugate(s) in the exposed cell-surface membrane of susceptible insect cells acts as a receptor and/or modulator for the specific interaction with the protoxin/activated toxin of the delta-endotoxin of Bacillus thuringiensis var. kurstaki. As candidates, the total neutral and acidic fraction glycolipids, and the isolated neutral glycosphingolipid components, were screened for binding activity by the thin layer chromatogram overlay technique. The main protoxin/activated toxin-binding glycolipid in the neutral fraction (5B) had the structure: Gal(alpha 1-3)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer. The main protoxin/activated toxin-binding glycolipid in the acidic fraction was designated band 1, the structure of which is at present unknown. The possibility that the component 5B carbohydrate sequence may also function as a toxin-binding site of relevant insect plasma membrane glycoproteins is discussed.

Animals↗
PubMed1986

A murine monoclonal antibody detecting N-acetyl- and N-glycolyl-GM2: characterization of cell surface reactivity.

Antisera reactive with the ganglioside GM2 were raised by immunizing C57BL/6 mice with the C57BL/6 melanoma JB-RH. Fusion with NS-1 was performed using splenic mononuclear cells from a mouse with high antibody titer. An immunoglobulin M monoclonal antibody (monoclonal antibody 5-3) was identified which was reactive with an antigen that was resistant to heat, trypsin, and Pronase. A panel of purified glycolipids was used to determine the specificity of monoclonal antibody 5-3. Reactivity was restricted to N-acetyl- and N-glycolyl-GM2. No reactivity was detected with asialo-GM2 or other gangliosides. Monoclonal antibody 5-3 was used to define the expression of GM2 on the cell surface of cultured human normal and malignant cells. Reactivity was seen with cell lines derived from 8 of 8 astrocytomas, 5 of 5 neuroblastomas, 7 of 9 sarcomas, 4 of 18 human melanomas, 2 of 4 murine melanomas, 4 of 37 epithelial cancers and with 0 of 6 skin fibroblast and 0 of 2 brain fibroblast lines. GM2, like GD2 and GD3, appears to be a differentiation antigen largely restricted to cells of neuroectodermal origin.

Animals↗
PubMed1985

Glycosphingolipids in insects. Chemical structures of ceramide tetra-, penta-, hexa-, and heptasaccharides from Calliphora vicina pupae (Insecta: Diptera).

Four neutal fraction glycosphingolipids, designated components 4-7, were purified from the pupae of Calliphora vicina and isolated by the use of high performance liquid chromatography. Their chemical structures were determined to be: GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer; GalNAc(alpha 1-4)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer and Gal(alpha 1-3)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer; Gal(beta 1-3)GalNAc(alpha 1-4)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer; and GlcNAC(beta 1-3)Gal(beta 1-3)GalNAc(alpha 1-4)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer. By the use of specific exoglycosidases, it was possible to assign anomeric configurations to all the sugar residues present. Analysis of the ceramide moiety by electron-impact mass spectrometry revealed the dominant fatty acid and sphingoid to be arachidic acid (C20:0) and tetradecasphing-4-enine, respectively.

Carbohydrates↗
PubMed1985

Glycosphingolipids in insects. Chemical structures of ceramide monosaccharide, disaccharide, and trisaccharide from pupae of Calliphora vicina (Insecta: Diptera).

The presence of glycosphingolipids in the pupae of the blowfly, Calliphora vicina, was established. The thin layer chromatographic pattern of the total neutral glycolipids revealed the presence of more than 13 components, the major one being ceramide monohexoside. By the use of high performance liquid chromatography, the three simplest components were isolated and their chemical structures determined: Glc(beta 1-1)Cer, Man(beta 1-4)-Glc(beta 1-1)Cer [with minor component Gal(beta 1-4)Glc(beta 1-1)Cer] and GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)-Cer. The ceramide composition of the parent insect glycosphingolipids is dominated by the 20:0 fatty acid, arachidic acid, and the sphingoid tetradecasphing-4-enine.

Animals↗
PubMed1985

Sodium butyrate selectively inhibits host cell glycoprotein synthesis in human fibroblasts infected with cytomegalovirus.

Host cell as well as viral DNA synthesis in human fibroblasts infected with human cytomegalovirus was found to be largely resistant even to high concentrations of sodium butyrate. Likewise, production of viral progeny was reduced by 1-2 orders of magnitude but not abolished. On the other hand, the drug allowed (modified) glycosylation only of viral polypeptides whereas that of host proteins was suppressed. Immunofluorescence studies on living cells suggested that butyrate may interfere with processing and intracellular transport of virus-specific surface membrane antigens.

Antigens, Surface↗
PubMed1985

Studies on the interaction of Clostridium perfringens sialidase with sialic acid linked to the internal galactose in monosialogangliotetraosyl ceramide.

Investigation of the action of highly purified Clostridium perfringens sialidase on ganglioside II3Neu5Ac-Gg4Cer and its oligosaccharide II3Neu5Ac-Gg4, in the presence and absence of sodium cholate, extend earlier results obtained with impure enzyme fractions. Sialidase labeled with 125I was found to bind to various ganglioside substrate micelles, including II3Neu5Ac-Gg4Cer, and to mixed ganglioside-sodium cholate micelles. No binding occurred between the enzyme and the ganglioside-derived oligosaccharide II3Neu5Ac-Gg4, even when radioactive II3Neu5Ac-Gg4-[3H]ol was used. The binding of sialidase to micellar substrate is a condition for enzymic hydrolysis. Correspondingly, II3Neu5Ac-Gg4Cer and II3Neu5Ac-Gg4Cer-sodium cholate micelles were hydrolyzed by the enzyme but II3Neu5Ac-Gg4 was not. Ganglioside oligosaccharide analogues containing an amino function at the reducing terminus or between two oligosaccharide chains, II3Neu5Ac-Gg4-NH2 and (II3Neu5Ac-Gg4)2NH, were hydrolyzed in the absence of cholate. A synthetic analogue of II3Neu5Ac-Gg4Cer containing only the fatty acid moiety and not the sphingosine residue (I1-deoxy-I1-stearamido-II3-monosialo-gangliotetraitol ) behaved as the ganglioside in the presence and absence of sodium cholate.

Chemical Phenomena↗
PubMed1984

Glycosphingolipid synthesis in human fibroblasts infected by cytomegalovirus.

Infection of serum-deprived human foreskin fibroblasts (HFF-cells) by cytomegalovirus (HCMV) resulted in enhanced precursor incorporation into glycosphingolipids (GSL). Analysis of the component patterns revealed a unique biphasic effect on the rate labeling of neutral GSL. Early during infection or in the presence of phosphonoacetic acid, radiolabel was found predominantly in ceramide tri- and tetrahexoside, whereas late after infection label in ceramide monohexoside exceeded that in the other components. Determination of the chemical amounts of neutral GSL components from infected cultures supported the view of increased biosynthesis of ceramide tri- and tetrahexoside early, and of ceramide monohexoside late postinfection. Changes, comparable to those observed under the influence of "early" viral functions were observed also during S-phase of serum-stimulated HFF cells. With respect to acidic GSL a decrease of metabolic labeling occurred late during infection. Relatively little alteration was found in the component pattern.

Cell Differentiation↗