Biomedical subjects

R W Stoddart

Publications and source records attributed to R W Stoddart.

At least 37 records · Page 2Linked to original sources

PubMed1994

Lectin-histochemical analysis of glycans in ovine and bovine near-term placental binucleate cells.

Chorionic binucleate cells (BNC) occur in several ruminants including cow, deer, goat and sheep. They migrate through the chorionic tight junction to fuse with uterine epithelial cells and discharge their granules into maternal connective tissue. We have compared the BNC of near-term, resin-embedded, ovine and bovine placentae using 15 biotinylated lectins and an avidinperoxidase revealing system. There was pronounced conservation of saccharides between the two species. Several sub-types of N-glycan were present, with highly branched structures being abundant, as shown by Galanthus nivalis, Pisum sativum and Phaseolus vulgaris (leuko) agglutinins. Among the non-reducing terminal saccharides conserved were GalNAc alpha 1,3(Fuc alpha 1,2)-Gal beta 1,4GlcNAc beta 1-, GalNAc alpha 1,6Gal beta 1-, Gal beta 1-, Gal beta 1,4GlcNAc- and Gal beta 1,3GalNAc alpha 1- shown by Dolichos biflorus, Wisteria floribunda, Erythrina cristagalli, and Maclura pomifera agglutinins, respectively. Arachis hypogaea and Glycine max agglutinins tended to bind to bovine BNC at different stages of maturity, while fucosyl residues detectable by Tetragonolobus purpureus and Ulex europaeus-1 agglutinins were not observed in either species. The only major difference related to sialyl residues, with alpha 2,3-linked sialic acid being present in bovine (Maackia amurensis, Limax flavus) and alpha 2,6 sialic acid being present in ovine (Sambucus nigra agglutinin) cells. This conservation of glycan may be related to glycosylation of peptide hormones in the granules, and may thus be important in the targeting of these hormones to their receptors.

Animals↗

PubMed1994

Localisation of alpha(2,3) and alpha(2,6) linked terminal sialic acid groups in human trabecular meshwork.

Sialic acid specific lectins were used to localise isomers of sialyl glycosides in human trabecular meshwork (TM) at the ultrastructural level. A lectin immunogold method demonstrated that sialic groups were concentrated on the endothelial surface of Schlemm's canal (SC) and in the adjacent juxta-canalicular tissue (JCT). One sialyl glycoside, alpha(2,6) linked N-acetyl neuraminic acid, was present mainly on the luminal aspect of the SC endothelium and in the cytoplasm of the JCT cells. Another, alpha(2,3) linked N-acetyl neuraminic acid, was localised predominantly to the extracellular fibrillar material of the JCT. The existence of a topographical segregation of these two sialyl glycosides within the TM supports the view that highly charged anionic molecules may be of significance in regulating aqueous outflow.

Adult↗

PubMed1993

Ulcer-associated cell lineage ('pyloric metaplasia') in Crohn's disease: a lectin histochemical study.

Chronic intestinal ulceration in Crohn's disease is associated with the development of an epidermal growth factor-secreting cell lineage, or 'ulcer-associated cell lineage' (UACL). Expression of oligosaccharides by UACL was studied using a panel of 25 biotinylated lectins with an avidin peroxidase revealing system and compared with that of adult and fetal Brunner's glands, gastric antral mucosa, and 'gastric metaplasia' within the duodenum, in order to clarify further the interrelationships of these lineages. UACL was obtained from ileal resections performed for Crohn's disease. Lectin binding of the glandular component of UACL closely resembled that of antral mucosal glands and also that of fetal and adult Brunner's glands. Lectin binding of the ductal component of immature UACL, in which a surface component had not developed, resembled that of the gland. The surface and ductal components of mature UACL showed a distinct lectin-binding profile, which was very different from that of the gland, but closely resembled that of antral foveolar epithelium and 'gastric metaplasia' within the duodenum. It is concluded that there is differentiation of UACL from the glandular to surface components and that oligosaccharide expression of the lineage reflects that of normal Brunner's gland and gastric antral mucosa.

Brunner Glands↗

PubMed1993

Pelvic ileo-anal reservoirs: a lectin histochemical study.

Pelvic ileo-anal reservoir (ileal pouch) formation is now a common surgical approach to the management of long-standing inflammatory bowel disease. The ileal mucosa in this new environment responds with changes in morphology and histochemical reactivity, as shown by conventional techniques. In this study, pre-pouch ileum and pouch ileal mucosa from 20 patients have been examined with a large panel of lectins using an avidin-biotin-peroxidase technique, with appropriate negative controls and sugar-inhibition studies. Changes were noted between pre-pouch ileum and the pouch mucosa which were complex, and no single alteration was seen in every case. Most variations related to saccharide sequences near the non-reducing termini of O- and N-linked glycans. Many of these were seen with lectins having requirements for terminal fucosyl residues, and to a lesser extent for galactosyl sequences, and were most obvious in the epithelium. Some of the changes occurred with such frequency as to suggest a direct response to surgery, but many of the variations were likely to be adaptive responses, possibly related to inflammation or infection. The changes in glycans were largely additive and could not be explained as a consequence of the actions of bacterial glycosidases. These alterations suggest that reservoir mucosa undergoes an adaptive response to the new intraluminal environment, without frank colonic metaplasia, and some changes occur to a greater degree in patients with pouchitis.

Adult↗

PubMed1993

Histochemical analysis of rat testicular glycoconjugates. 3. Non-reducing terminal residues in seminiferous tubules.

Lectins of Helix pomatia (HPA), Glycine max (SBA), Vicia villosa (VVA), Dolichos biflorus (DBA), Ulex europaeus (UEA-1), Tetragonolobus purpureus (LTA), Griffonia simplicifolia (BSA-1B4), Maclura pomifera (MPA), Sambucus nigra (SNA) and Maackia amurensis (MAA) were used to explore the distribution of saccharides characteristic of non-reducing termini of O- and N-linked glycoprotein glycans in the seminiferous tubules of rat testis. Sialyl residues (both alpha 2,3- and alpha 2,6-linked, as shown by MAA and SNA respectively) and alpha-L-fucosyl residues (shown by UEA-1 and LTA) were expressed on spermatogonia, spermatocytes and spermatozoa, but not on spermatids. In contrast, 2-deoxy-2-acetamido-alpha-D-galactosyl termini were abundant on spermatozoa, but not on any of their precursors (as shown by HPA, SBA and VVA). All occurred on both O- and N-linked glycans. Sertoli cells expressed small amounts of fucose and alpha 2,3-linked sialic acid, and abundant alpha 2,6 sialyl residues, largely on N-glycans. alpha-Galactosyl residues were readily detected on the tubular basement membrane, but not elsewhere.

Animals↗

PubMed1993

Glycan localization within the human interphotoreceptor matrix and photoreceptor inner and outer segments.

Glycoconjugates are likely to be of fundamental importance in the complex interactions between photoreceptors and the retinal pigment epithelium, but few have been characterized, especially in human tissue. As a preliminary step towards determining their biological functions in health and disease, a lectin-based histochemical study of the glycan expression of human outer retina was performed on glutaraldehyde-fixed, semi-thin, resin-embedded sections. The interphotoreceptor matrix and photoreceptor plasma-lemmata expressed complex bisected and non-bisected biantennary and/or triantennary N-glycans. In addition, both the rod and cone outer segments bound strongly Galanthus nivalis agglutinin (which binds terminal Man alpha 1, 3Man-) and the rod outer segments bound selectively the isolectin II of Bandeiraea simplicifolia (which binds terminal GlcNAc-). The cilia of the rods and cones were labelled selectively with Glycine max agglutinin after sialidase pretreatment. Four putative glycan outer sequences were identified within the interphotoreceptor matrix: (i) sialylated glycans with subterminal GalNAc alpha 1,3GalNAc-sequences; (ii) a sialylated type with subterminal N-acetyl-lactosamine residues; (iii) Gal beta 1,3GalNAc alpha 1- residues which were substituted with sialic acid except in the cone matrix sheath; (iv) GalNAc alpha 1,6Gal beta 1- residues which were substituted in part with sialic acid. The sialic acid expression throughout was predominantly of the 2,3-linked form with lesser amounts of 2,6-linkage, and rod-associated structures (including the surrounding interphotoreceptor matrix) were labelled more strongly with the sialic acid-binding lectins than cone-associated structures (including the cone matrix sheath).

Adolescent↗

PubMed1992

Histochemical analysis of rat testicular glycoconjugates. 1. Subsets of N-linked saccharides in seminiferous tubules.

The distribution of N-linked glycans in rat testis has been probed using a panel of lectins derived from Galanthus nivalis (snowdrop, GNA), Canavalia ensiformis (jack bean, Con A), Lens culinaris (lentil, LCA), Pisum sativum (garden pea, PSA) and Phaseolus vulgaris, erythro- and leucoagglutinins (kidney bean, ePHA and lPHA). Several classes of N-linked glycan were identified in the spermatogenic series, and during differentiation into spermatozoa they altered in both their pattern of distribution and relative abundance. A population of tetra-antennary, non-bisected, complex glycans, detected by lPHA, was lost during the transition from spermatogonia to spermatocytes, while high-mannose structures were acquired; these were most abundant in spermatocytes, as were bi- and tri-antennary complex, non-bisected glycans, the latter becoming increasingly abundant on acrosomes and spermatozoa. Their bisected counterparts were more generally expressed throughout spermatogenic cells, although marked localization onto acrosomes and nuclear caps was again seen. Transition from spermatocytes to spermatids involved mainly changes of the acrosomal granule and nuclear cap, which were carried through to the final stages of differentiation. Sertoli cell surfaces and cytoplasmic granules showed a high level of N-glycan expression.

Animals↗

PubMed1992

Histochemical analysis of rat testicular glycoconjugates. 2. Beta-galactosyl residues in O- and N-linked glycans in seminiferous tubules.

Rat testes have been examined with a panel of lectins that bind specifically to oligosaccharide sequences having terminal or subterminal beta-galactosyl residues in O-linked glycans, or in the outer chains of complex N-linked glycans: Arachis hypogaea (peanut, AHA), Erythrina cristagalli (coral tree, ECA), Ricinus communis (castor bean, RCA120) and Abrus precatorius (jequirity bean, APA) agglutinins. Pretreatment of sections with neuraminidase, beta-galactosidase and removal of alkali-labile O-linked sequences by beta-elimination allowed the structure of these glycans to be further explored. In spermatogonia and spermatocytes there was little evidence of glycans terminating in beta-galactosyl residues, although these were present at non-reducing terminals as sialylgalactosides. The acrosome contained two subsets of O-linked glycans terminating in sialylgalactosides, while the nuclear cap showed at least two subsets of N-linked sialylgalactosyl as well as O-linked glycans. Spermatozoa exhibited minor changes in the pattern of glycosylation, although the overall pattern of beta-galactosyl expression was similar. Binding to Sertoli cells showed the presence of some unsubstituted beta-galactosyl terminals on O-linked glycans but few such N-linked residues, while terminal beta-galactosides were scanty in tubular basement membranes.

Animals↗

PubMed1992

Altered patterns of glycosylation on rat lymphocytes associated with activation.

The expression of cell-surface carbohydrates on rat lymphocytes was investigated by flow cytometry using a panel of lectins. A small group of lectins was identified, all with a main binding requirement of N-acetylgalactosamine that bound to all B lymphocytes but only to activated T lymphocytes expressing the interleukin-2 (IL-2) receptor (as shown by staining with the monoclonal antibody OX39). Studies demonstrated that five of these lectins competed for the same binding site, while others did not. With the knowledge of the binding requirements of these lectins, a structure can be deduced for the carbohydrate moiety which appears on T lymphocytes when activated.

Animals↗

PubMed1991

Lectin binding sites in normal, scarred, and lattice dystrophy corneas.

Normal, scarred, and dystrophic corneas were histochemically probed with a panel of 16 lectins by means of an avidin-biotin revealing system. Normal corneal epithelial cells, keratocytes, and endothelial cells expressed at least two distinct N-linked oligosaccharide subsets, of the non-bisected, biantennary and bisected, bi-/triantennary types. Corneal scars stained variably with the lectin subsets described above, and with Maclura pomifera agglutinin. Lattice dystrophy corneas showed a loss of the oligosaccharide expression observed on the plasma membranes of normal epithelial cells, and there was concurrent deposition of extracellular glycoprotein within the corneal stroma, which was of the same oligosaccharide subsets as were lost from the epithelial cell plasma membranes. This extracellular stromal glycoprotein was far more widely deposited than the amyloid and extended well beyond the stromal scarring. We propose that these observations are related and that in lattice corneal dystrophy a glycoprotein(s) is shed from the plasma membranes of epithelial cells and sequestrated within the corneal stroma, where it subsequently stimulates amyloid deposition.

Adult↗

PubMed1990

Lectin histochemistry of the mast cell: heterogeneity of rodent and human mast cell populations.

Mast cell granules contain a variety of N-linked saccharides. Heterogeneity of the expression of these saccharides in mast cells was studied in rodent and human tissues which were so selected as to contain all the mast cell subsets previously identified using other criteria. Dermal and intestinal mucosal mast cells were stained with lectins using an avidin-biotin system. It was found that dermal and subepidermal mast cells in the rat and mouse, and mucosal and dermal human mast cells showed very similar lectin binding properties to each other, with a fine variation in the intensity of staining with certain lectins. Rat mucosal mast cells, however, showed a distinctive pattern of lectin binding which was not seen in mast cells from any other tissue studied. The chemical basis of the differences seen were deduced and the possible significance of these structural variations is discussed.

Alcian Blue↗

PubMed1989

Human salivary gland glycoconjugates: a lectin histochemical study.

The glycoconjugate content of normal salivary glands has been extensively investigated in humans by biochemical means and in non-human mammals by histochemical methods. However, there have been few histochemical studies of human tissues. This paper describes the findings obtained in parotid, submandibular and minor salivary glands by applying a panel of 13 biotinylated lectins, directed against a range of N-linked, fucosylated and galactosylated sequences, using an avidin-peroxidase technique, with appropriate enzymatic and inhibitory sugar controls. The results were generally in accord with those observed in biochemical assays but the use of lectin histochemistry permitted the localization in situ of small amounts of oligosaccharide and, therefore, allowed the recognition of subtle tissue differences. This study expands the current knowledge on the glycoconjugate composition of salivary glands and their lectin histochemistry and serves as a baseline for further studies, particularly in the field of neoplasia.

Adolescent↗

PubMed1989

Saccharide expression on wounded endothelial cell monolayers in vitro.

Monolayer cultures of porcine aortic endothelial cells were used as a model of the endothelium of large arteries. Linear wounds were produced in such cultures by scraping and the subsequent sequence of events in nearby cells was analysed. The earliest detectable event was cellular spreading at the margins of the wounds (2 h) followed by cell migration (starting at 6-8 h) and cell proliferation in regions adjacent to the wound (16 h and later). Cell spreading was associated with the appearance of saccharides selectively at the spreading margins of the cells, which bound the lectins, ConA, LCA and PSA, and were sensitive to alpha-mannosidase. Terminal alpha-mannosyl residues were therefore present. The appearance of these saccharides suggests a mechanism by which monocytes might adhere to and/or migrate through the endothelium of vessels at sites of cellular response to injury.

Animals↗

PubMed1988

Saccharides of senile plaques and neurofibrillary tangles in Alzheimer's disease.

The contribution that oligosaccharides might make to the structure of the senile plaque and the neurofibrillary tangle was investigated using lectin histochemistry in 9 patients with Alzheimer's disease. One group of 4 lectins diffusely stained the neurites of senile plaques whereas two groups of 6 different lectins stained neurofibrillary tangles within neuronal perikarya and plaque neurites. Neuraminidase pretreatment abolished staining of tangles by one of these latter groups, but did not affect staining by the other group. Senile plaque core amyloid failed to stain with any lectin. It is concluded that oligosaccharides may contribute, but in different ways, to glycoprotein or glycolipid residues that form an integral part of the structure of the senile plaque and the neurofibrillary tangle.

Aged↗

PubMed1988

An ultrastructural study of the morphology and lectin-binding properties of human mast cell granules.

The morphological characteristics and lectin-binding properties of mast cell granules from four human neurofibromata are described. Ultrastructural examination of the granules revealed that some contained dense cores, others had membranous configurations and some forms were intermediate between the two. A round electron-lucent area was present in some granules. After treatment with biotinylated lectins (10 micrograms ml-1) followed by an avidin-peroxidase revealing system (5 micrograms ml-1 in 0.125 M Tris-buffered saline with 0.347 M NaCl, pH 7.6), mast cell granules strongly bound Concanavalin A, garden pea, lentil, wheatgerm, erythro- and leuco-kidney bean lectins. This indicated the presence of abundant N-linked complex-type saccharide sequences. Soybean and peanut lectins showed only weak binding, while the presence of sparse alpha-L-fucosyl terminals was indicated by the weak binding of winged pea lectin. The staining intensity of wheatgerm lectin was considerably reduced when incubated in the presence of its specific competing sugar tri-N-acetylchitotriose. Despite a wide variety of morphological differences between granules, all showed similar staining patterns and all granules within a single cell shared the same binding characteristics.

Cytoplasmic Granules↗

PubMed1988

Lectin histochemistry of the mast cell: a light microscopical study.

The purpose of this study was to determine if human mast cell granules contain non-repeating oligosaccharide sequences. The binding of lectins to human mast cell granules was studied using a panel of 11 lectins variously selective for both N- and O-linked oligosaccharide sequences. The tissues were principally derived from cutaneous neurofibromata and benign and malignant breast diseases, that is, readily available human material with a known high content of mast cells. Lectin-binding sites in the formalin-fixed paraffin-embedded or resin-embedded material was visualized by means of biotinylated lectins and an avidin-peroxidase technique for light microscopy. The results indicate that human mast cell granules contain abundant N-linked sequences, but few or no O-linked residues. These sequences appear to be mostly in the form of non-bisected highly branched or smaller biantennate sequences, although variable positive binding with erythrophytohaemagglutinin was observed, indicating some degree of bisection.

Histocytochemistry↗

PubMed1988

Method for showing human spermatogenesis using Arachis hypogaea (AHA) lectin.

Using biotinylated Arachis hypogaea agglutinin (AHA) or peanut lectin (PNA) and an avidin-peroxidase procedure, the various stages of spermatid development were visualised with great clarity; a light haematoxylin counterstain permitted the easy recognition of spermatogenic cells in the same section. This method is particularly useful in the interpretation of poorly fixed material and may be helpful in studies of cyclical maturation of spermatozoa, irrespective of whether the material is obtained at biopsy or necropsy.

Acrosome↗

PubMed1988

Epicardial lymphocytes: an autopsy study.

Lymphocytes appear as a diffuse infiltrate within the epicardium in the second trimester of intrauterine life, and can be found there throughout adult life. Aggregates are found in some individuals, and are strongly associated with the presence of old myocardial infarction.

Adult↗