Genetic and sex-related differences in the structure of submandibular glycoconjugates

Mucoadhesion dependence of pharmaceutical polymers on mucosa characteristics

Well known mucoadhesive polymers such as Carbopol 974P and Pharmacoat 606 and three different mucosas (sublingual, oesophageal and duodenal bovine) were used to verify how the mucoadhesive properties of materials may depend on the mucosa characteristics and if a polymer may reveal more mucoadhesive than another and vice versa by changing the type of interacting mucosa. So, tablets of Carbopol 974P and Pharmacoat 606 were prepared and their mucoadhesion on the three mucosas was set in terms of maximum load and work of detachment, using a texture analyzer. At the same time, mucosas were characterized by immunohistochemical techniques and lectin histochemistry. Results obtained from the Tensile test analyses show that the adhesive power of the two polymers is different in the three mucosas. Particularly, in the sublingual mucosa, Carbopol was more mucoadhesive than Pharmacoat. On the contrary, Pharmacoat was more mucoadhesive than Carbopol in duodenal mucosa. The significantly different behavior of polymers was correlated with the desquamation layer thickness and the differential sialic acid and fucose exposition in the targeted mucosas.

Glycosylations in demilunar and central acinar cells of the submandibular salivary gland of ferret investigated by lectin histochemistry

'Resting' submandibular salivary glands obtained post-mortem from mature ferrets of both sexes were examined here. The binding patterns of labelled lectins applied to paraffin sections of tissue slivers fixed in an aldehyde-HgCl2 mixture and the effects of pretreatment procedures on the results were assessed lightmicroscopically. Lectins with affinity for terminal GalNAc residues (DBA, SBA) bound preferentially to demilunar acinar cells which were also strongly reactive with Fuc-directed UEA I. In contrast, lectins with affinity for neuraminic acid (SNA, WGA) bound to central acinar cells where consistent binding of DBA and SNA occurred only after neuraminidase digestion, and variation in the binding of UEA I was seen. The reactivities corresponded with the distribution of secretory granules, but staining in Golgi-like areas occurred in central acinar cells with PNA lectin. The results suggest that glycosylations are more advanced in central than demilunar acinar cells of the ferret submandibular gland. Possibly demilunar and central acinar cells reflect phenotypic changes of a single secretory cell, the 'central' acinar phenotype being influenced by incorporation of neuraminic acid in glycoprotein side chains and by increased Golgi activity.

Digestive System 1

This chapter deals with the digestive system. The major and minor salivary glands and their secretions also represent and integral part of the protective mechanism of the oral cavity, and derangement of saliva production may lead to loss of integrity of the oral mucosa. Drug-induced abnormalities of taste sensation are also well-described phenomena occurring in man although human studies are necessary for the detection of these effects. Inflammation of the oral cavity may involve the buccal mucosa, the gingiva (gingivitis), the tongue (glossitis), and the peridontal tissues (peridontitis). Therapeutic agents can induce inflammatory lesions in the tongue. Moreover, a protective layer of mucus, a visco-elastic material containing high molecular weight glycoproteins produced by the major and minor salivary glands, covers the stratified squamous mucosa of the oral cavity. Salivary secretions also possess digestive enzyme activity although in herbivores and carnivores, it is usually low in contrast to high digestive enzyme activity in omnivorous species.

Histochemical study of lectin binding in the human fetal minor salivary glands

The emerging synthesis of glycoconjugates containing specific oligosaccharides in developing human fetal labial and lingual salivary glands has been investigated by lectin histochemistry. An avidin-biotin technique was used to study the binding of lectins from Ulex europeus I (UEA-I), Dolichos biflorus (DBA), Glycine maximus (SBA), Helix pomatia (HPA), Arachis hypogaea (PNA) and Triticum vulgare (WGA) to specific sugars on sections of tissue from labial glands, glands of Blandin and Nuhn, glands of von Ebner and the dorsoposterior lingual salivary glands. Incipient synthesis of glycoconjugates in early glands and their presence in the cells and ducts of the later glands was shown. The study also showed a time-related increase in both staining intensity and binding sites of serous acinar cells from all glands and for all lectins used. For mucous cells, peak intensity of staining was reached by the middle phase of development. During later gland development this intensity was maintained in dorsoposterior lingual glands but tended to decline in labial glands. The various lectins showed different degrees of binding but UEA-I lectin generally bound the L-fucose sugar group in all salivary glands at all gestational ages. The results showed that lectins appear to bind to the oligosaccharides on epithelial cell surfaces of fetal salivary glands at all stages of development. The degree of change depends upon the stage of differentiation and maturation of the glands.

Sexual dimorphism of the kidney in the NMRI mouse as shown by Dolichos biflorus agglutinin labelling

The histological affinity pattern of Dolichos biflorus agglutinin (DBA) in kidneys from mice (NMRI, Balb/c, CBA) and rats (Wistar) fixed by perfusion with formalin, Bouin, or HgCl2 was investigated with a horseradish peroxidase conjugate. The animals were examined from fetal stage to adulthood. Adult female NMRI mice exhibited constant DBA labelling, with DBA binding to cells of the proximal and collecting tubules. Moreover the vascular endothelium of the renal papilla was found to be DBA-positive in 50% of adult female animals. In contrast, there was only very little DBA binding in the kidneys of male adult NMRI mice. There was no sexual dimorphism in lectin labelling in kidneys from other strains of mice or from rats.

Histochemical analysis of glycoconjugates in gelatinous membranes of the gerbil's inner ear

The gelatinous membranes of the gerbil inner ear were analyzed histochemically for glycoconjugates with a battery of twenty horseradish peroxidase-conjugated lectins. Glycoconjugates with mannose (Man) and/or glucose (Glc), galactose (Gal), fucose (Fuc), N-acetylglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc) and N-acetylneuraminic acid (NeuAc) were detected in the tectorial and otolithic membranes and cupula. Differences in lectin reactivity were observed between tectorial and vestibular membranes and also among zones and between the medial and lateral regions of the middle zone of the tectorial membrane. The distribution of staining differed markedly for several lectins that bind specifically to GalNAc or to GlcNAc but vary in affinity for oligosaccharides containing these sugars in different sequences or linkages. The findings suggest presence of the terminal disaccharides GalNAc alpha 1,3Gal in tectorial membrane and Gal beta 1,3GalNAc in vestibular membranes. Lectin binding profiles provided evidence that the limbal zone's fibrous and attachment layers contain mainly O-glycosidically linked oligosaccharides whereas the middle zone's medial fibrous layer contains both O- and N-linked chains. The remaining regions of the tectorial membrane contain mainly N-linked oligosaccharides with bisected biantennary type chains predominating. Additionally, the marginal band and the middle zone's basal layer contain abundant N-linked oligosaccharides with a triantennary structure.

Immunochemistry and immunogenicity of low molecular weight human salivary mucin

The purposes of this study were to examine the immunogenicity of the low molecular weight human salivary mucin (MG2) and determine its distribution within major and minor human salivary glands. Anti-MG2 sera were produced in Balb/c mice by a variety of immunization schedules. Chromatographically or electrophoretically purified MG2 and partially purified mucin chromatographic fractions exposed to mild denaturing conditions were not immunogenic. Only MG2 without prior exposure to urea or guanidine was able to elicit an immune response. A murine anti-MG2 monoclonal antibody (clone 1/F9) was produced and its monospecificity confirmed by immuno-dot blotting and SDS-PAGE Western transfer. Clone 1/F9 (IgG1; kappa) was of moderate affinity and was directed to a Pronase- and TPCK trypsin-sensitive but periodate-resistant epitope which was not blood group- or sialic acid-specific. Immunocytochemical studies of frozen tissue sections with clone 1/F9 using both indirect and direct methods revealed that MG2 was more heterogeneously distributed within submandibular than labial glands and was not found in parotid or palatine glands. The use of a polyclonal rabbit anti-MG2 reagent in either frozen or paraffin-embedded tissues gave the same immunocytochemical results as those obtained with the monoclonal antibody.

Glycoconjugate unique to migrating primordial germ cells differs with genera

Previous cytochemical studies showing that rat primordial germ cells (PGCs) possess a unique surface glycoconjugate containing terminal alpha-N-acetylgalactosamine were extended in this study to determine whether a similar distinctive glycoconjugate coats the surface of PGCs in the mouse. The results showed that mouse PGCs fail to react with peroxidase-conjugated lectins specific for localizing glycoconjugate with terminal N-acetylgalactosamine. All available lectin conjugates with affinity for other terminal sugars or internal sugar linkages also failed to stain mouse PGCs except for the conjugates that bind to alpha-fucose. One fucose-specific lectin conjugate stained only PGCs in the early mouse embryo but stained additional sites in more mature embryos and lost reactivity with PGCs after gestational day 14. Another fucose-specific conjugate stained PGCs until day 15, but with less selectivity, and a third such conjugate bound to several sites, but not to PGCs. The results suggest that the developmental mechanisms mediating cellular interaction, migration, and differentiation may be similar in different genera, but the specific structure of the cell surface glycoconjugate involved in these mechanisms differs.

Comparison of Dolichos biflorus lectin and other lectin-horseradish peroxidase conjugates in staining of cutaneous blood vessels in the hairless mini-pig

Angiogenesis is necessary for normal growth, wound healing, and plays a key role in many pathologic processes. A variety of endothelial markers have been used to investigate angiogenesis. Unfortunately, excellent markers for vascular endothelium in human tissues exhibit little or no staining of endothelia in tissues of other animal species, including the pig. We are interested in the hairless Yucatan strain of mini-pig as an animal model for studying cutaneous wound healing because its skin is histologically and functionally very similar to that of man. Hoping to find a specific marker to identify vascular endothelium in the mini-pig, we therefore screened a battery of 11 different lectin-horseradish peroxidase conjugates. Based on specificity and staining intensity, Dolichos biflorus agglutinin (DBA) was chosen from this battery to investigate vascular changes in the healing of cutaneous wounds in the mini-pig. When compared with routine histologic sections stained with hematoxylin and eosin, blood vessels were much easier to identify in sections stained histochemically with DBA. Lectin histochemistry was particularly useful in investigations of early events in angiogenesis during wound healing when newly derived capillary buds and minute blood vessels were obscured in normal histologic sections by an inflammatory cell infiltrate associated with the healing wound. Ultrastructural lectin cytochemistry revealed staining along the luminal surface and the basolateral plasmalemma of endothelial cells. Histochemical staining with DBA promises to provide a useful method for further investigation of angiogenesis and other vascular phenomena in a variety of normal and pathologic processes using the hairless Yucatan strain of mini-pig as the animal model.

Immunochemistry of high molecular-weight human salivary mucin

The purpose of this study was to determine the distribution of mucin glycoprotein 1 (MG1) within submandibular, parotid, labial and palatine salivary tissues. Formalin-fixed and frozen tissue sections were examined histochemically with PAS, Alcian blue and Meyer's mucicarmine, and immunocytochemically with an anti-mucin glycoprotein 1 monoclonal antibody (clone 3/E8). Clone 3/E8 was produced in Balb/c mice using mucin-enriched chromatographic fractions from submandibular-sublingual saliva. The monospecificity of 3/E8 was confirmed by immuno-dot blotting and SDS-PAGE/electrophoretic transfer. Clone 3/E8 (IgG1; kappa) was of moderate affinity, and was directed to a carbohydrate-containing, TPCK-trypsin-insensitive and pronase-insensitive epitope on this mucin, which was not blood-group specific. The location of mucin glycoprotein 1 was determined by both indirect (peroxidase-antiperoxidase) and direct methods. Mucin glycoprotein 1 was localized within all labial acini examined, but was not found within parotid tissues. Histochemical methods stained all submandibular, palatine and labial acini, but immunocytochemistry with monoclonal antibody revealed heterogeneous staining with clone 3/E8 in submandibular and palatine tissues. These findings suggest the presence of mucin glycoprotein 1-specific acinar cell subpopulations within human submandibular and palatine salivary tissues.

Lectin histochemistry of the embryonic heart: expression of terminal and penultimate galactose residues in developing rats and chicks

Rat embryos at days 10-18 of gestation and chicken embryos at days 3-6 of incubation were fixed and processed for lectin histochemistry. The distribution of binding sites for a lectin from the peanut Arachis hypogaea (PNA) conjugated to horseradish peroxidase (HRP) was determined on tissue sections both before and after enzymatic cleavage of sialic acid with neuraminidase (sialidase). Endocardial cushion tissue in the rat, but not in the chick, reacted with PNA-HRP prior to digestion with sialidase. Endocardium of both species (12 and 13 days in rat, 5 and 6 days in chick), particularly at the level of endocardial cushions, reacted strongly with the sialidase-PNA sequence; this staining decreased markedly after day 14 of gestation in the rat. PNA binding sites capped by sialic acid were most abundant in the developing rat heart during the critical period of endocardial cushion formation and decreased as development proceeded. The marked changes in the appearance and distribution of cardiac cell and tissue glycoconjugates during cardiogenesis support the concept that rapid changes occur in the structure of complex carbohydrates during embryonic and fetal development. The findings also suggest that such glycosylation-related events may be species specific.

Lectin histochemistry of the embryonic heart: fucose-specific lectin binding sites in developing rats and chicks

Glycoconjugates, particularly their sugar side chains, play important roles in embryonic development. Changes in cell-surface-associated glycoconjugates are known to affect cell differentiation, cellular interactions, and other developmental phenomena during embryogenesis. The embryonic heart goes through a series of complicated morphologic events during development. Of particular interest is morphogenesis of the outflow tract. This region of the embryonic heart originates from more than one cell population and undergoes a complex process of septation during formation of the great vessels. Histochemical analysis with a series of fucose-specific lectins conjugated to horseradish peroxidase has revealed the presence of a fucosylated glycoconjugate in the outflow tract of the developing heart. The results reveal further that the expression of the fucosylated glycoconjugate is stage-dependent and thus probably genetically regulated. The timing and distribution of staining with the lectin OFA suggest that this fucosylated glycoconjugate may play a role in directing the migration of neural crest cells into the heart and subsequent formation of the conus septum.

The proper role of nerves in salivary secretion: a review

Consideration of the history of this subject has created a perspective which helps one to appreciate how errors in thinking have occurred and why some have persisted, despite subsequent improvements in information. The most enduring misconception has been that the drying of the mouth under stress is due to sympathetic inhibitory fibers, a view that must be eradicated, for such fibers do not exist. The inhibition is due to central influences from higher centers acting on the salivary centers and thereby suppressing reflex activity. Wide variations exist in the neuro-effector arrangements and in the cellular responses in different glands from different species. Myoepithelial cells are usually contracted by both parasympathetic and sympathetic nerves. The blood vessels also receive a dual innervation, but parasympathetic impulses cause vasodilatation as part of secretion, whereas the sympathetic vasoconstrictor fibers are part of a more generalized vascular control system and not a direct part of the reflex secretory sympathetic pathway. Parasympathetic drive usually provides the main stimulus for fluid formation by parenchymal cells, whereas sympathetic nerves tend to increase the output of pre-formed components from certain cells. Absence of nerve impulses causes variable atrophic and other metabolic effects on the parenchymal cells. Evidence is beginning to accrue that certain nerve impulses may influence resynthetic activities. Vacuolation, often found experimentally after strong stimulation, also occurs to a variable extent in certain cells as a normal part of reflex secretion and may therefore have an effect on the components entering the saliva. If rupture of vacuoles occurs, then this may contribute to the salivary amylase that is present in the blood. Recent evidence points to the possibility that, even in a monomorphic gland, not all of the components necessarily enter nerve-induced saliva in "parallel" proportions. Consideration of current information has enabled some provisional generalizations about the roles of the secretory nerves to be suggested in the summary, but they must not be considered immutable.