凝集素受体分布与膀胱癌预后关系的初步探讨

目的探讨凝集素受体分布与膀胱癌预后的关系。方法应用生物素标记的花生凝集素（PNA）、麦胚凝集素（WGA）及扁豆凝集素（LCA）等3种凝集素对52例人体膀胱移行细胞癌进行亲合组织化学法研究。结果发现PNA、WGA受体阳性率在浸润性肿瘤中明显高于浅表性肿瘤（P＜0.05）。术后2年以上复发的膀胱癌中，PNA受体的阳性率低于2年以内复发的膀胱癌中该受体的阳性率（P＜0.05）。结论PNA、WGA受体阳性率与膀眈癌浸润深度有关；肿瘤组织内PNA受体可能是膀胱癌术后预测预后的指标之一。     

Histochemical and ultrastructural characteristics of tubular complexes in human acute pancreatitis

The morphologic characteristics of ductlike tubular complexes were studied in human acute pancreatitis. Pancreatic specimens were obtained from 10 patients who were operated on for acute pancreatitis. Immunocytochemistry for pancreatic enzymes, keratin, actin, and carcinoembryonic antigen were combined with lectin-binding studies and ultrastructural investigations. Irrespective of clinical onset and duration of pancreatitis, tubular complexes situated in the vicinity of fat necrosis were observed in all patients. Intermediate forms of ductlike structures were characterized by widening of acinar lumina, decreased height of acinar cells, and large autophagic vacuoles. These structures bound all of the lectins employed and retained their immunoreactivity to secretory proteins. Typical tubular complexes were composed of low cuboidal or flattened cells surrounding a large acinar lumen. They revealed a loss for pancreatic enzymes, a reduced lectin-binding for l-fucose and N-acetylgalactosamine, and an increase for cytoskeletal proteins (keratin, actin). It is concluded that tubular complexes in human acute pancreatitis represent degenerating acinar cells which lost their secretory and membrane characteristics.     

Reduced expression of mannose-specific receptors on murine peripheral blood polymorphonuclear leukocytes following prolonged anaesthesia with different inhalation agents

Inhalation anaesthetic agents are known to depress phagocytic functions such as mobilization, attachment, chemotactic motility, engulfment and intracellular killing. Mannose-specific sugar receptors on the surface of leukocytes are involved in a series of phagocytosis-related activities. To investigate the effect of anaesthesia on the expression of this type of sugar receptor, mice were anaesthetized with halothane, enflurane and isoflurane. The presence of mannose-binding receptors on peripheral blood polymorphonuclear leukocytes was examined glycocytochemically using the biotinylated neoglycoprotein mannosylated bovine serum albumin. Prolonged administration of inhalation anaesthetic agents, especially halothane, markedly depressed expression of mannose-specific receptors. This reduction may possibly contribute to postoperative immunodepression, resulting from the impaired cellular interaction which is involved in the phagocytic function of granulocytes.     

Role of carbohydrates in repair of human respiratory epithelium using an in vitro model

BACKGROUND: The epithelial layer in the conducting airway provides a primary protective barrier. Repair of this barrier normally occurs rapidly after damage, but is compromised in diseases such as asthma. OBJECTIVE: We have developed a human in vitro model system to test our hypothesis that cell surface glycoconjugate-based interactions are required for the normal repair of damaged epithelium. METHODS: Lectins having narrow carbohydrate specificities were used to identify and block specific carbohydrate moieties on human airway-derived epithelial cells in culture. RESULTS: The lectin wheat germ agglutinin bound to N-acetyl glucosamine and inhibited the repair of epithelial damage while having little effect on cell viability. In contrast, other N-acetyl glucosamine binding lectins had no effect even when bound to the cell surface. The involvement of glycoconjugates was confirmed by pre-incubating the lectin with its specific sugar, preventing the inhibition of repair. CONCLUSION: These results indicate that lectin-binding sites are involved in epithelial repair and may be important in the repetitive cycles of injury and repair seen in asthma. This model system provides an insight into the role of glycoconjugates and will help to determine the function of specific carbohydrate groups in epithelial repair. These may present a target for therapeutic intervention in respiratory and other diseases.     

Binding and Transport of Some Bioadhesive Plant Lectins Across Caco-2 Cell Monolayers

Pharmaceutical Research -     

Differential expression of glycans in the hippocampus of rats trained on an inhibitory learning paradigm

The glycan chains of glycoconjugates play important roles in cell–cell and cell–matrix interactions. In the CNS, previous studies on learning and memory suggest the importance of oligosaccharides attached to glycoconjugates in the modulation of synaptic connections. We studied the hippocampal glycan distribution of rats subject to an inhibitory avoidance task. The expression of glycans was examined by lectin‐histochemistry using Vicia villosa lectin (VVL) for terminal α/β N‐acetylgalactosamine (α/β GalNAc); Galanthus nivalus lectin (GNL) for terminal mannose α‐1,3 (Man α‐1,3); Peanut agglutinin (PNA) for galactose β‐1,3N‐acetylgalactosamine (Gal β‐1,3 GalNAc); Erythrina cristagalli lectin (ECL) for galactose β‐1,4 N‐acetylglucosamine (Gal β‐1,4 GlcNAc); Sambucus nigra lectin (SNA) for sialic acid α‐2.6 galactose (SA α‐2,6 Gal); Maackia amurensis lectin II (MAL II) for sialic acid α‐2,3 (SA α‐2,3); Wheat germ agglutinin (WGA) for terminal N‐acetylglucosamine with/without sialic acid (GlcNAc wo SA); succynilated WGA (sWGA) for terminal N‐acetylglucosamine without sialic acid (terminal GlcNAc without SA); Griffonia simplicifolia lectin II (GSL II) for terminal α/β N‐acetylglucosamine (α/β GlcNAc terminal); and Lotus tetragonolobus lectin (LTL) α–fucose. Two groups of 10 animals were examined: non‐trained (Control) and Trained rats. ECL, sWGA and GSL II were negative for both groups in all the hippocampal subfields studied. For both groups, VVL was negative in CA4 and granular cells of the Dentate Gyrus (DG) and LTL was negative in the CA4 subfield. Expression of α/β GalNAc, α ‐fucose and GlcNAc in other hippocampal subfields was positive, with no differences between groups. However, expression of Man α‐1,3 was significantly higher in the CA1, CA2, CA3, and CA4 subfields in the Trained group. On the other hand, expression of Gal β‐1,3 GalNAc was significantly low in CA4 and DG in the Trained group. In conclusion, the results here presented indicate that the exposure of rats to an associative behavioral paradigm related to declarative memory, involves some regulatory mechanism/s for the differential patterns of glycan expression.     

Circular dichroism studies on conformational transitions of phytohemagglutinins effected by some alcohols

The effects of methanol, ethanol, 1-propanol and 2,2,2,-trifluoroethanol (TFE) on conformation of 10 phytohemagglutinins (lectins) were examined by applying the circular dichroism (CD) method. Concanavalin A and the lectins isolated from pea (Pisum sativum), lentil (Lens culinaris), soybean (Glycine max), peanut (Arachis hypogaea), Dolichos biflorus, Sophora japonica, Lotus tetragonolobus, Ulex europaeus I, and Phaseolus vulgaris (leucoagglutinin) were used. Slight changes in the structure of these proteins were observed at relatively low concentrations (5–20 vol. %, pH 7.2–8.2, at 22–25°) of the perturbants, and the effectiveness of the alcohols increased with their concentration and molecular weight. The circular dichroism bands related to the aromatic side chain chromophores decreased in the presence of the alcohols. The secondary structure was reorganized by high concentrations (30–80 vol. %) of the alcohols, as indicated by CD at 187–250 nm. Curves typical for proteins of relatively high α-helix content (strong positive CD bands at 191 nm and negative bands at 206–208 and 222 nm) were recorded in the presence of high concentrations of trifluoroethanol.     

Binding of four lectins to normal human oral mucosa

Abstract – The binding affinity of four lectins to normal human buccal mucosa was studied. Biopsies (diameter 2 mm) were obtained from eight healthy volunteers. Cryostat cut sections (4 μm thick) were stained with the following FITC-Conjugated lectins: Ulex europaeus I (UEA I) soybean (SBA), peanut (PNA) and Lens culinarius (LCA). The specificity of the staining was controlled using the respective sugars. UEA I stained the epithelial intercellular spaces from the upper stratum (str.) spinosum to str. superficiale. Vascular endothelium in the connective tissue was also stained by UEA I. SBA stained the intercellular spaces of str. spinosum, whereas PNA stained both str. spinosum and str. superficiale. LCA stained the basement membrane and the intercellular areas of str. basale and str. spinosum. The elastic fibers of connective tissue were probably also stained by LCA. The lack of suprabasal staining by SBA and PNA indicates accelerated cell turnover as compared to normal human epidermis.     

Partial characterization of lectin binding sites of retinal photoreceptor outer segments and interphotoreceptor matrix

We have used cytochemistry together with exoglycosidase digestion and polyacrylamide gel electrophoresis to partially characterize lectin binding sites of the interphotoreceptor matrix and of photoreceptor outer segments. In order to obtain uniform access of reagents to all regions of the preparation, we have used a procedure in which plastic sections are etched with sodium ethoxide prior to cytochemical analysis. Neuraminidase pretreatment of plastic-embedded sections of Xenopus laevis eyecups leads to a loss of wheat germ agglutinin binding and a concomitant appearance of Ricinus communis agglutinin binding to the interphotoreceptor matrix. In contrast, wheat germ agglutinin binding to the outer segments is not altered by the neuraminidase pretreatment. These results suggest that wheat germ agglutinin binding sites of interphotoreceptor matrix are sialoglyconjugates and that outer segment binding sites are not sialoglycoconjugates. Enzyme digestions followed by lectin cytochemistry of matrix polypeptides separated by polyacrylamide gel electrophoresis do not identify a likely candidate to give rise to the cytochemical staining patterns. Lectin cytochemistry of retinas from which the interphotoreceptor matrix has been extracted do not show a loss of wheat germ agglutinin binding sites to the matrix. These results suggest that the major wheat germ agglutinin binding sites in the interphotoreceptor matrix are to as yet unidentified sialoglycoconjugates.     

Fluoresceinated lectins as probe for cell surface changes associated with lymphocyte transformation

Lectins are plant-derived proteins with specific affinities for simple or complex sugars and are potentially useful tools for investigation of the carbohydrate structure of the cell surface. A panel of fluoresceinated lectins was used to study the cell surface changes associated with lymphocyte transformation. The major determinants detected on peripheral blood lymphocytes were αD-mannose,β-D-galactose and N-acetyl-glucosamine. Phytohemagglutinin transformation was associated with increased binding of lectins specific for N-acetyl-galactosamine. MOLT-4, a T-lymphoblast cell line in continuous culture, was associated with increased binding of lectins specific for N-acetyl-galactosamine and L-fucose. Application of fluoresceinated lectins may be a useful tool in the classification of lymphoid cells.