Biomedical subjects

H J Gabius

Publications and source records attributed to H J Gabius.

At least 109 records · Page 6Linked to original sources

PubMed1998

Pulmonary metastases of breast carcinomas: ligandohistochemical, nuclear, and structural analysis of primary and metastatic tumors with emphasis on period of occurrence of metastases and survival.

BACKGROUND AND OBJECTIVES: Pulmonary metastases of breast carcinomas have a high frequency and are often subject to surgical intervention. To contribute to advances in the knowledge about morphometric and biochemical parameters of primary tumors and their metastatic lesions, analysis of syntactic structure and thermodynamic aspects as well as of expression of distinct glycohistochemical features with respect to period of metastasis occurrence and patient survival is desirable. METHODS: Clinical history, surgical findings, histopathological reports, survival of the patients with a maximum follow-up of 15 years, and paraffin blocks of 32 breast carcinoma specimens and their pulmonary metastases were examined. Only potentially curative resections of both the breast carcinoma and their metastases have been included for analysis. The following markers were applied: neoglycoconjugates with histoblood group A- and H-trisaccharides, lactose, alpha-N-acetyl-D-galactosamine and the Forssman disaccharide, a polyclonal immunoglobulin G fraction from human serum with specificity for 9-0-acetylated sialic acid, which is a tumor marker for melanomas, the serum lectins serum amyloid P component and mannan-binding lectin, the mannose-specific plant lectin concanavalin A, and monoclonal antibodies specific for estrogen and progesterone receptors, respectively. In addition, measurements of the integrated optical density (IOD) and tissue structure were performed. RESULTS: The frequency of expression of hormone receptors and expression of binding capacities to most of the applied probes was similar between the primary and metastatic tumors; however, it varied markedly between different patients. For the IOD parameters, a close association between the primary tumors and their metastases was seen, especially a rather low S-phase-related tumor cell fraction and a high percentage of tumor cells with an IOD >5C. The mean time for the development of intrapulmonary metastases measured 43 months. It was considerably longer in progesterone receptor-negative tumors (49.7 months) and those with a lack of expression of sites with specificity for the Forssman disaccharide (48.7 months). The survival was positively correlated with the presence of binding capacity of histoblood group A-trisaccharide and certain structural parameters, especially the structural entropy and its current. The presence of estrogen and progesterone receptors was not associated with the total survival at a statistically significant level. CONCLUSIONS: Histochemical features between the primary breast carcinoma and their intrapulmonary metastases can evidently vary. Analysis of the hormone receptor status in metastatic lesions seems to be useful for diagnostic purposes only in rare cases, i.e., distinguishing metastases from primary lung carcinoma. Nonetheless, the survival of patients with metastasizing breast carcinoma is associated with features of the primary tumors, especially the detection of binding capacities for the Forssman disaccharide and the histoblood group A-trisaccharide. Extent of lymph node involvement of the breast carcinoma is not prognostic for later pulmonary involvement.

Adult↗

PubMed1998

Inability of galactoside-specific mistletoe lectin to inhibit N-methyl-N-nitrosourea-induced tumor development in the urinary bladder of rats and to mediate a local cellular immune response after long-term administration.

Extracts from mistletoe (Viscum album L.) are assumed to exert an antineoplastic activity through their toxicity at high doses or by immunomodulation by nanogram quantities of a lectin. They are used as an unconventional therapy modality in the management of a wide range of cancer diseases, although no anticancer potential has yet been demonstrated. This prompted us to study the effect of galactoside-specific lectin (VAA)--a major protein constituent of mistletoe with immunomodulatory properties--on chemically induced tumor development in the urinary bladder of rats and on the local cellular immune response after long-term administration. To induce urothelial neoplasms N-methyl-N-nitrosourea (MNU) was administered in a single intravesical dose (7.5 mg/kg body weight). Highly purified VAA was given subcutaneously at its immunomodulatory dose (1 ng/kg body weight) twice a week over the total experimental period of 15 months. The incidences of epithelial bladder tumors were 25.0% following administration of MNU alone and 22.9% in the rats additionally receiving VAA, which proved not to be significantly different (P = 0.81). Quantitative immunohistochemistry analyzing a panel of immune cell types, including T lymphocytes, T helper/inducer cells (CD4), T suppressor/cytotoxic cells (CD8), T cells positive for interleukin-2 receptor (CD25), B lymphocytes and plasma cells, macrophages, natural killer cells, granulocytes and all leukocytes expressing the leukocyte common antigen (CD45), yielded no evidence for the ability of VAA to stimulate a substantial cellular immunological reaction in the wall of the normal urinary bladder or during urothelial carcinogenesis. In conclusion, the current experimental findings provide no support at all that the galactoside-specific mistletoe lectin is capable of inhibiting chemically induced bladder carcinogenesis and triggering a local cellular immune response after prolonged application. It thus seems highly improbable that commercial mistletoe preparations or VAA will be effective in the management of human bladder cancer by a cell-mediated immunological mechanism.

Adjuvants, Immunologic↗

PubMed1998

Fusion of macrophages on an implant surface is associated with down-regulated expression of ligands for galectin-1 and -3 in the rat.

Galectins have a wide range of biological activities which are elicited by binding to appropriate glycoligands. Besides regulation of the expression of the galectins the extent of the presence of suitable binding sites will be relevant to infer the cellular responsiveness to this class of sugar receptors. Thus ligand presentation requires monitoring by the tissue lectin. We demonstrate the expression of galectin-3 by macrophages and foreign-body giant multinucleate cells colonizing a cellophane implant in the rat by the A1D6 monoclonal antibody. The extents of ligand presence are visualized in the same cells by biotinylated galectin-3 and also by galectin-1 which is produced by diverse mammalian cell types and widely distributed. Labeled mistletoe (VAA) and tomato (LEA) lectins are used as tools to assess the degree of similarity of the binding profile between endogenous and exogenous proteins. The presentation of alpha-galactosides is monitored with a natural immunoglobulin G subfraction obtained by two consecutive affinity chromatography steps. The binding of labeled galectins and plant lectins was significantly lower to foreign-body giant multinucleate cells than to mononuclear macrophages. The application of the alpha-galactoside-specific probe yielded no significant staining. The potential problem of epitope accessibility could be excluded by the concomitant positivity obtained with an IgG subfraction with selectivity to beta-galactosides also obtained by affinity chromatography. These results provide no evidence for a role of alpha-galactosides for the binding of galectins in the rat macrophages colonizing the implant. The reduced level of expression of glycoligands for galectin-1 and -3 in foreign-body giant multinucleate cells in contrast with the mononuclear macrophages suggests an inhibitory influence of macrophage fusion on the expression of galectin-reactive molecules.

Animals↗

PubMed1998

Thermodynamic parameters of the interaction of Urtica dioica agglutinin with N-acetylglucosamine and its oligomers.

The interaction between Urtica dioica agglutinin (UDA) and N-acetylglucosamine (GlcNAc) and its beta(1-4)-linked oligomers was studied by fluorescence titration and isothermal titration microcalorimetry. UDA possesses one significant binding site that can be measured calorimetrically. This site is composed of three subsites, each subsite accommodating one GlcNAc residue. The interaction is enthalpically driven, and the binding area of UDA is characterized by a deltaH of interaction for a given oligosaccharide considerably smaller than that of wheat germ agglutinin (WGA), despite the fact that they both belong to a family of proteins composed entirely of hevein domains. Relatively high deltaCp values of the UDA-carbohydrate interactions and more favorable entropy term compared to WGA suggest that binding of the carbohydrate ligands by UDA has a higher hydrophobic component than that of WGA.

Acetylglucosamine↗

PubMed1998

The how and why of protein-carbohydrate interaction: a primer to the theoretical concept and a guide to application in drug design.

The common principles of molecular recognition with cooperative or bidentate hydrogen bonds, dispersion forces and hydrophobic packing govern the specificity of protein-carbohydrate interaction. Enthalpy/entropy-compensation is also valid, maintaining KD-values in the range of 30 mM to 200 nM. The individual contributions of the enthalpic and entropic factors which originate from the receptor, the ligand and/or the solvent to the overall free energy change can at least be estimated by a combination of computer-assisted molecular modeling, NMR spectroscopy of the reactants before and after complex formation and thermodynamic measurements. The delineation of adaptable parameters such as ligand or receptor side chain flexibility points to a route to practicable guidelines for a rational design of mimetics in glycosciences.

Carbohydrates↗

PubMed1998

Diffuse pulmonary hemosiderosis after exposure to pesticides. A case report.

This report describes the clinical, radiological, microscopical and ligandohistochemical findings in a 17-year-old woman who suffered from an acute onset of pulmonary hemosiderosis after inhalation of pesticides used for the cultivation of strawberries. She complained of headache, dyspnea, rhinitis, weakness and recurrent severe hemoptysis. Chest radiographs revealed bilateral patchy infiltrates, predominantly in the lower parts of both lungs. The consecutive severe anemia was treated by multiple blood transfusions which were repeated every 4-5 days. Open lung biopsies displayed signs of diffuse hemorrhage with hemosiderin-loaded macrophages, some hyaline membranes, focal fibroid deposits with intermingled histiocytes, mild interstitial fibrosis and focal intra-alveolar calcified bodies surrounded by foreign body giant cells. Analysis of endogenous lectins failed to demonstrate expression of binding capacities for maltose, fucose, mannose, lactose and sialic acid, Neither binding capacities for the macrophage-migration-inhibitory factor nor its presence, as analyzed by labeled sarcolectin, could be detected histochemically. The light microscopical findings are consistent with a longer-lasting diffuse pulmonary hemosiderosis; the presence of calcified bodies and foreign body giant cells (including the ligandohistochemical data) argues for a causal role of inhaled substances. The patient's clinical course improved after cyclophosphamide treatment, which restored her ability to work and released her from the need for recurrent blood transfusions.

Adolescent↗

PubMed1998

Detection of inflammation- and neoplasia-associated alterations in human large intestine using plant/invertebrate lectins, galectin-1 and neoglycoproteins.

Commonly, plant and invertebrate lectins are accepted glycohistochemical tools for the analysis of normal and altered structures of glycans in histology and pathology. Mammalian lectins and neoglycoproteins are recent additions to this panel for the detection of lectin-reactive carbohydrate epitopes and glycoligand-binding sites. The binding profiles of these three types of probes were comparatively analyzed in normal, inflamed and neoplastic large intestine. In normal colonic mucosa the intracellular distribution of glycoconjugates and carbohydrate ligand-binding sites in enterocytes reveals a differential binding of lectins with different specificity and of neoglycoproteins to the Golgi apparatus, the rough and smooth endoplasmic reticulum and the apical cell surface. The accessible glycoligand-binding sites and the lectin-reactive carbohydrate epitopes detected by galectin-1 show the same pattern of intracellular location excluding the apical cell surface. Lectin-reactive carbohydrate epitopes detected by plant lectins of identical monosaccharide specificity as the endogenous lectin [Ricinus communis agglutinin-I (RCA-I), Viscum album agglutinin (VAA)], however, clearly differ with respect to their intracellular distribution. Maturation-associated differences and heterogeneity in glycohistochemical properties of epithelial cells and non-epithelial cells (macrophages, dendritic cells, lymphocytes) are found. Dissimilarities in the fine structural ligand recognition of lectins with nominal specificity to the same monosaccharide have been demonstrated for the galactoside-specific lectins RCA-I, VAA and galectin-1 as well as the N-acetylgalactosamine (GalNAc)-specific lectins Dolichos biflorus agglutinin (DBA), soybean agglutinin (SBA) and Helix pomatia agglutinin in normal mucosa and in acute appendicitis. Acute inflammation of the intestinal mucosa found in acute phlegmonous appendicitis is associated with selective changes of glycosylation of mucin in goblet cells mainly of lower and middle crypt segments resulting in an increase of DBA- and SBA-binding sites in the goblet cell population. Appendicitis causes no detectable alteration of neoglycoprotein binding. In contrast, tumorigenesis of colonic adenoma is characterized by increases in lectin-reactive galactose (Gal; Gal-beta1, 3-GalNAc), fucose and N-acetylglucosamine moieties and by enhanced presentation of respective carbohydrate ligand-binding capacity. This work reveals that endogenous lectins and neoglycoproteins are valuable glycohistochemical tools supplementing the well-known analytic capacities of plant lectins in the fields of gastrointestinal anatomy and gastroenteropathology.

Adenoma↗

PubMed1998

Beyond plant lectin histochemistry: preparation and application of markers to visualize the cellular capacity for protein-carbohydrate recognition.

Oligosaccharides can store biological information. In this respect, their capacity even outmatches that of oligo- and polymeric structures of nucleotides and amino acids. Protein-carbohydrate interactions are thus considered to be involved in the regulation of diverse cellular activities. Over decades, plant lectins have proven valuable for assessing structural aspects of the enormous variety of carbohydrate epitopes and for monitoring spatially and/or temporally restricted patterns of expression. If the presence of these epitopes and the alterations in their occurrence bear physiological relevance, one reasonable possibility is that the visualized saccharides serve as ligands in an operative protein-carbohydrate recognition system. To support the validity of this hypothesis, receptor sites for a sugar compound must be localized. Carrier-immobilized carbohydrates (neoglycoconjugates) are adequate for this purpose. Chemical synthesis gains access to such probes. In the first stage, the presence of binding sites such as lectins in the tissue is ascertained. The next step toward proving the outlined hypothesis is the application of the first localized then purified endogenous receptors as glycohistochemical markers. It is essential to point out that the fine specificities of plant and animal lectins can differ, although they share an identical monosaccharide specificity. Thus, neoglycoconjugates for localizing sugar ligand-binding proteins and endogenous lectins to detect suitable binding partners are promising probes to enhance our knowledge about the capacities of cells to be engaged in protein-carbohydrate recognition in situ.

Biomarkers↗

PubMed1998

Glycohistochemical properties of malignancies of lung and pleura.

Based upon the reasoning that protein-carbohydrate recognition is involved in diverse intercellular activities including growth control and cell motility 14 probes have been employed to characterize epitope presence in sections of 80 cases with operated lung carcinomas, 20 patients with mesothelioma, and 20 cases with non-malignant lung diseases. As parts of the innate immune system with supposed relevance for host defense the mannan-binding lectin (MBL) and serum amyloid P component (SAP) were employed. The naturally occurring immunoglobulin G fractions with selectivity for alphaa-galactosides (alpha+) and beta-galactosides (beta+) and their subfractions with enhanced target selectivity (alpha+beta-,alpha-beta+) allowed the monitoring of expression of reactive sites for these autoantibodies as a step to elucidate potential anti-tumor activity. Due to the diversity of cellular galactoside-containing glycoconjugates two galectins and a plant lectin were included. As a measure of receptor activities for carbohydrates, neoglycoconjugates with alpha-galactose, the B-disaccharide, the Forssman-disaccharide, and alpha-glucose as histochemically crucial ligand part were tested in addition to an antibody against heparin-binding lectin. Quantitative image analysis revealed significant differences between cases with small cell and non-small cell lung cancer for the plant lectin and one galectin, cases with non-tumorous lung disease and lung carcinoma for serum amyloid P component and the beta-galactoside-selective autoantibody fraction. Prognostic relevance was observed for the presence of glucose-specific sites in small cell lung cancer and meso-thelioma cases, and of galectin- and alpha-galactoside-selective immunoglobulin G fraction-binding sites in non-small cell lung cancer patients.

Adenocarcinoma↗

PubMed1998

Formation of lactose-resistant aggregates of human platelets induced by the mistletoe lectin and differential signaling responses to cell contact formation by the lectin or thrombin.

Human platelets afford a suitable and physiologically relevant model to study receptor-dependent cell aggregation and ensuing biosignaling reactions. Since cell surface glycoconjugates can serve as ligands in recognitive protein--carbohydrate interactions, it is of interest to investigate the reactivity of such epitopes for a plant lectin and the elicited intracellular responses. Therefore, the galactose-specific lectin (Viscum album agglutinin, VAA) was employed as a tool for this purpose. It was found that VAA induced platelet aggregation at a concentration of 2.5 microgram/ml using 2.5. 108 cells/ml, composed of the formation of both lactose-sensitive (Lac+) and lactose-resistant (Lac-) intercellular contacts. Lac- aggregates were formed only by metabolically active platelets of about 70% of the samples from the group of studied volunteers. The requirement of metabolic activity for formation of these contacts which no longer depend on lectin--ligand recognition was underscored by the lack of their appearance in the presence of metabolic inhibitors such as nordihydroguaiaretic acid, trifluoperazine, N-ethylmaleimide and menadione. With respect to biosignaling, the effective aggregation of platelets did not affect the basal level of Ca2+ in cells and reduced the rate of the menadione-dependent generation of H2O2. In parallel series platelet aggregation induced by bovine thrombin (0.03 U/ml) triggered an increase in the cytoplasmic Ca2+ level and an enhancement of the H2O2 generation. Overall, these results imply metabolically controlled post-binding reactions which strengthen the lectin-induced cell association and demonstrate differential responses with respect to the Ca2+ level and H2O2-generation between lectin- or thrombin-mediated aggregation of human platelets.

Animals↗

PubMed1998

Modification of the functional activity of neutrophils treated with acute phase response proteins.

The effects of alpha1-acidic glycoprotein (AGP) and its subfractions (glycoforms) with different affinity for concanavalin A on generation of H2O2 by human neutrophils exposed to stimulators of different nature, namely, galactose-specific mistletoe (Viscum album) lectin (VAA), digitonin, and N-formyl-Met-Leu-Phe, a chemotactic peptide (FMLP), were studied. Within the concentration range of 13-500 microgram/ml, AGP and its glycoforms produced dose-dependent inhibition of digitonin-induced cell responses. AGP also inhibited the VAA-induced generation of H2O2; however, this cell response was potentiated by low concentrations (50 microgram/ml) of AGP and AGP-A. FMLP induced the most consistent response of neutrophils, which changed only slightly in the presence of AGP and AGP-B; however, low concentrations of AGP-A inhibited this response. The presence of sialic acid in the terminal position of carbohydrate antennae of AGP is not necessary for its inhibitory effect on human neutrophil respiratory burst because asialo-AGP (250 microgram/ml) inhibited H2O2 generation by cells stimulated with agonists of the NADPH-oxidase system of phagocytes. In contrast to AGP, two other acute phase response proteins displaying a lectin activity (C-reactive protein and serum amyloid P component) within the concentration range of 10-100 microgram/ml produced no significant effect on H2O2 generation by stimulated neutrophils. These data suggest that AGP is an effector molecule responsible for feedback regulation of the functional activity of neutrophils.

C-Reactive Protein↗

PubMed1998

Association of prognosis in surgically treated lung cancer patients with cytometric, histometric and ligand histochemical properties: with an emphasis on structural entropy.

OBJECTIVE: To explore new tumor features for refined category formation that permits the tailoring of individualized treatment schemes in lung cancer. STUDY DESIGN: Survival data on patients from six independent studies on cases with surgically treated lung cancer, primary lung carcinoids or metastasizing breast carcinoma (including data on primary breast carcinoma) were analyzed by nonhierarchic multivariant discriminant analysis with respect to a set of cytometric/histometric and immunohistochemical/ligand histochemical parameters. The number of stem lines, S-phase-related tumor cell fraction and the extent of structural entropy and its current were measured. In addition, the expression of binding capacities for histo-blood group trisacharides, galectins, the alpha/beta-interferon antagonist sarcolectin, the lymphokine macrophage migration inhibitory factor and a monoclonal antibody to the Le(y) epitope was monitored for insight into aspects of immunologic and biologic behavior. RESULTS: In all studies, a correlation between tumor parameters, according to TNM stage and survival, was seen. In order to refine this category formation, at least certain selected features should provide an even more stringent association than TNM stages. Indeed, statistical correlation of the cytometric and histometric parameters as well as the expression of receptors for the two histo-blood group trisaccharides, ligands for the galectins (CL-16, CL-14) and macrophage migration inhibitory factor was stronger than that of TNM stage. A large amount of the current of structural entropy was especially highly significantly associated with poor survival. This observation could be verified in each of the different studies. CONCLUSION: The obtained data strongly support the notion that thermodynamic evaluation of tumor growth focusing on the "entropy distance" of the tumor from its environment is a promising perspective warranting extended studies. Additionally, glycohistochemical features, including binding capacities for histo-blood group trisaccharides, have the potential to aid in establishment of a biologic marker set for tumor staging.

Biomarkers, Tumor↗

PubMed1997

Involvement of laser photo-CIDNP (chemically induced dynamic nuclear polarization)-reactive amino acid side chains in ligand binding by galactoside-specific lectins in solution.

For proteins in solution the validity of certain crystallographic parameters can be ascertained by a combination of molecular-dynamics (MD) simulations and NMR spectroscopy. Using the laser photo-CIDNP (chemically induced dynamic nuclear polarization) technique as a measure for surface accessibility of histidine, tyrosine and tryptophan, the spectra of bovine galectin-1 and Erythrina corallodendron lectin (EcorL) are readily reconcilable with the crystallographic data for these two proteins. The results emphasise the role of Trp68/Trp69 for carbohydrate binding in bovine galectin-1/chicken galectins and of Trp194 in murine galectin-3. This feature derived from the crystal structure of bovine galectin-1 is maintained in solution for the prototype human homologue, two avian galectins and the chimera-type murine galectin-3, as the spectra corroborate the CIDNP-inferable spatial parameters of the four calculated models for binding-site architecture. In EcorL, Tyr106/Tyr108 are constituents of the extended combining pocket, which can be shielded in solution by ligand presence. Discrepancies between results from modelling and CIDNP measurements concern primarily the lack of reactivity of histidine residues for human and avian prototype galectins and of Tyr82/Tyr229 of the plant lectin. Site-directed mutagenesis of EcorL is assumed to provide information on the role of a certain residue for functional aspects. When single-site mutants of EcorL ([Ala106]EcorL, [Ala108]EcorL, [Ala229]EcorL) were subjected to molecular-dynamics (MD) simulations, the apparent surface accessibilities even of spatially separated amino acid side chains could non-uniformly be affected. This conclusion is supported by the assessment of the spectra for the mutant proteins. On the basis of these CIDNP-results modelling of the binding-site architecture of the lectin indicates the occurrence of notable alterations in the orientation of Tyr106/Tyr108 phenyl rings. The implied potential effect of single-site mutations on conformational features of a protein will deserve attention for the interpretation of studies comparing wild-type and mutant proteins.

Amino Acid Sequence↗

PubMed1997

Animal lectins.

Protein and lipid glycosylation is no longer considered as a topic whose appeal is restricted to a limited number of analytical experts perseveringly pursuing the comprehensive cataloguing of structural variants. It is in fact arousing curiosity in various areas of basic and applied bioscience. Well founded by the conspicuous coding potential of the sugar part of cellular glycoconjugates which surpasses the storage capacity of oligonucleotide- or oligopeptide-based code systems, recognition of distinct oligosaccharide ligands by endogenous receptors, i.e. lectins and sugar-binding enzymes or antibodies, is increasingly being discovered to play salient roles in animal physiology. Having inevitably started with a descriptive stage, research on animal lectins has now undubitably reached maturity. Besides listing the current categories for lectin classification and providing presentations of the individual families and their presently delineated physiological significance, this review places special emphasis on tracing common structural and functional themes which appear to reverberate in nominally separated lectin and animal categories as well as lines of research which may come to fruition for medical sciences.

Animals↗

PubMed1997

Effect of chemical structure of hydrogels on the adhesion and phenotypic characteristics of human monocytes such as expression of galectins and other carbohydrate-binding sites.

The reactivity of diverse immune aspects to the presence of synthetic polymers represents one of the most important aspects of implantable device biocompatibility. In this report, we show the effect of the chemical structure of a synthetic polymer support on monocyte adhesion and selected phenotypic characteristics in vitro as a model for the initial steps of non-self-recognition of an implant. The extent of monocyte adhesion was significantly influenced by the support chemistry. The highest level of monocyte adhesion was observed on a surface copolymer of 2-hydroxyethyl methacrylate with dimethyl aminoethyl methacrylate relative to results of experiments in which poly(2-hydroxyethyl methacrylate) or the copolymer of 2-hydroxyethyl methacrylate with the sodium salt of methacrylic acid was used. Cell adhesion to the polymers tested and to glass was accompanied by enhanced expression of the carbohydrate-binding sites tested for asialoglycoprotein beta-galactosides such as galectins, beta-N-acetylgalactosamine, alpha-mannoside, specific lectin for heparin as well as the lymphokine-macrophage migration inhibitory factor in the monocytes tested. These results suggest the importance of monocyte adhesion to the biomaterial surface for their development into macrophages and further non-self-recognition of the implanted device.

Acetylgalactosamine↗

PubMed1997

Lack of an antitumoral effect of immunomodulatory galactoside-specific mistletoe lectin on N-methyl-N-nitrosourea-induced urinary bladder carcinogenesis in rats.

The aim of the present animal experiment was to study the effect of galactoside-specific lectin or agglutinin (VAA) from mistletoe (Viscum album L.) on chemically induced tumor development in the urinary bladder of rats. Since VAA has been shown to exert a remarkable immunomodulating effect, any change in tumor formation would indicate a lectin-triggered immune control of urothelial carcinogenesis in the used model. To produce vesical neoplasms the direct-acting urothelial carcinogen N-methyl-N-nitrosourea (MNU) was administered at a single intravesical dose (7.5 mg/kg body weight). Highly purified VAA was given subcutaneously twice a week at the immunomodulatory dose of 1 ng/kg body weight over a period of 6 months during the critical phases of tumor development. After a total experimental time of 15 months the incidence of epithelial bladder tumors was 29.3% in controls versus 27.9% in rats additionally receiving the lectin and thus not significantly different in both experimental groups. There were, moreover, no substantial differences in the histopathologic spectrum of epithelial tumors induced, their patterns of growth, grades of cellular malignancy and local extension. The frequency and histopathology of mesenchymal bladder tumors as well as the incidence and morphology of carcinomas of the ureters and renal pelves also proved to be similar in controls and in rats treated with VAA. In conclusion, the present data provide no evidence for a modifying or even inhibitory effect of the immunomodulatory galactoside-specific mistletoe lectin on experimental urothelial carcinogenesis.

Adjuvants, Immunologic↗

PubMed1997

Tyramine-containing poly(4-nitrophenylacrylate) as iodinatable ligand carrier in biodistribution analysis.

PURPOSE: Targeted label or drug delivery requires access to convenient carrier systems and methods for efficient ligand conjugation. The main purpose of this study is to design an iodinatable synthetic polymer, whose application in vivo in tumor-bearing mice is tested with several related carbohydrate ligands, namely ABH and Lewis blood group epitopes. METHODS: Tyramine and aminopropyl derivatives of the synthetic oligosaccharides were attached to poly(4-nitrophenylacrylate). Following iodination, the biodistribution of the sugar-free and the substituted polymers was determined in tumor-bearing mice. Flow cytofluorimetric analysis assessed tumor cell binding of further ligand types to human tumor cells in vitro. RESULTS: Quantitative ligand incorporation was achieved under mild conditions. Whereas the ligand-free poly[N-(2-hydroxyethyl)acrylamide] (MW 30 kDa) showed preferential accumulation in kidney, neoglycopolymers were found in substantial amounts in liver, kidney or spleen. The nature of the carbohydrate structure quantitatively influenced the distribution pattern. Tumor cell binding of blood group determinants and three further ligand types revealed non-uniform intensity in labeling and percentage of positive cells even in comparison between lines with identical histogenetic origin. CONCLUSIONS: Carbohydrate-exposing poly[N-(2-hydroxyethyl)acrylamide] polymers with tyramine as an iodine acceptor distribute in mice with a profile which is quantitatively influenced by small structural variations of the ligand part. Further refinement of the ligand structure may increase the level of selectivity for organ and tumor accumulation.

Acrylic Resins↗

PubMed1997

Comparison between intact and desialylated human serum amyloid P component by laser photo CIDNP (chemically induced dynamic nuclear polarization) technique: an indication for a conformational impact of sialic acid.

The human pentraxin serum amyloid P component (SAP) exhibits no microheterogeneity in its complex di-antennary glycan. To elucidate whether the removal of sialic acids from this glycoprotein might affect the accessibility of certain amino acid residues of the protein we employed the laser photo CIDNP approach as a sensitive tool. The CIDNP effect is generated by the interaction of a photoexcited dye with reactive amino acids and results in enhanced absorption- or emission-signals which can be observed for the three aromatic amino acids histidine, tryptophan, and tyrosine if they are accessible to the dye. Therefore, this technique can be applied to explore surface exposure of these amino acid residues. The respective spectra of SAP and enzymatically desialylated SAP were determined. Six tryptophan/histidine signals and one tyrosine signal are present in the aromatic part of the CIDNP difference spectrum of SAP. The corresponding spectrum of desialylated SAP shows remarkable alterations. The chemical shift of one Trp/His-characteristic signal is decreased by 0.1 ppm. One Trp/His-signal disappeared and a new one was formed in the CIDNP difference spectrum of desialylated SAP, while the other signals were unaffected. The Tyr signal has a clearly enhanced intensity in desialylated SAP. Therefore, the removal of sialic acid moieties from the single N-glycan of each monomer apparently affects surface presentation of distinct CIDNP-reactive amino acids of SAP [1]. A conformational change of the protein part of SAP in relation with a different orientation of the desialylated oligosaccharide chain in comparison to the complete one is a possible explanation of our CIDNP results.

Carbohydrate Conformation↗