Further studies of the principal glycoprotein from human saliva

An in vitro investigation of the role of high molecular weight human salivary sulphated glycoprotein in periodontal wound healing

High molecular weight human salivary sulphated glycoprotein (SGP) inhibits attachment of fibroblasts to cementum in vitro and thus may enhance periodontal wound healing by repair with long junctional epithelium. However, competitive inhibition by serum constituents might prevent adequate binding of SGP for this effect to occur in vivo. The primary aim of this study was to investigate the co-adsorption in vitro, of SGP, fibronectin (FN), and albumin (ALB) to synthetic hydroxyapatite (HA) from solutions of SGP/FN (62.5/2 micrograms/mL respectively), or SGP/FN/ALB (62.5/2/4 micrograms/mL), or from individual solutions of the agents as controls: Desorption of SGP and FN was studied by preabsorbing HA with SGP or FN and subsequently exposing it to the other agent, or to buffer only as control. Adsorbates were assayed after incubation periods of up to 26 hours using specific ELISAs. SGP displaced previously adsorbed FN after 3 hours and significantly inhibited adsorption of FN and ALB compared with controls. Neither FN or ALB had a significant effect on SGP adsorption. These results are consistent with the possibility that salivary adsorption to cementum during surgery might interfere with repopulation of the root by connective tissue cells and thus contribute to wound healing by repair rather than regeneration. Separate studies taken to validate the ELISA used for SGP determination showed that HA-bound SGP contained all constituents of native SGP as revealed by SDS-PAGE and that ion exchange chromatography of SGP gave 6 fractions (I through VI), of which only the most ionic (VI) was able to inhibit cell attachment in vitro.

Isolation and characterization of mucin from the serum of cystic fibrosis patients

Using monoclonal antibody 19-9, elevated levels of the sialyl Lea antigen (NeuAc alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNac beta 1-3R) are detected in serum from most cystic fibrosis patients. We now report further characterization of the serum antigen and evidence that it is on a mucin glycoprotein and not on glycolipids. The antigen has an apparent molecular weight greater than 2 X 10(6) by gel filtration on Sephacryl S-400. On density gradient centrifugation, the antigen has a density of 1.54 g/ml in cesium chloride and 1.42 g/ml in cesium chloride/4 M guanidine HCl. Immunostaining with monoclonal antibody 19-9 of lipid extracts from cystic fibrosis patient serum and erythrocytes does not detect any antigen on glycolipids. The antigen was purified by gel filtration and density gradient centrifugation. After tritium labeling of the sialic acid residues, sodium dodecyl sulfate gel electrophoresis separates two subunits with apparent molecular weights of 200,000 and 400,000. All of the labeled sialic acid is released as low molecular weight oligosaccharides after mild alkaline borohydride degradation. The purified antigen contains fucose, galactosamine, glucosamine, and galactose but no mannose and is enriched in the amino acids threonine, serine, glycine, proline, and alanine. The purified antigen binds several antibodies recognizing epitopes common to many mucins. Thus, the physical, biochemical, and immunochemical properties of the purified antigen indicate that the sialyl Lea antigen is present on mucins in the serum of cystic fibrosis patients.

A sulphated glycopeptide in human supragingival calculus extracts

A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component of cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.

Nonimmunologic aspects of caries resistance

A variety of components provide salivary secretions with an array of potentially effective means of combating cariogenic challenges. These defense factors range from a laissez-faire mechanical cleansing to exquisitely controlled production of highly specific antibodies. In between the two extremes are antibacterial systems whose operating characteristics are only beginning to be understood. These systems are well worth our attention. They may be the key to our understanding of variations in individual susceptibility, and could provide valuable leads for development of anticaries agents.

Some chemical characteristics of human minor salivary gland secretions

The minor salivary glands contribute to the composition of whole saliva, but little information has been available about their chemical constituents. Pilocarpine-stimulated labial and palatine secretion from 4 human subjects was investigated by paper and disc electrophoresis, immunochemical analysis, and for content of carbohydrates, amino acids, lipids, hexuronic acids and sulphate. No significant differences were noted between the labial and palatine secretions by any of the methods employed. The minor gland secretions appeared to consist mainly of mucosubstances, possibly with blood group specificity. In addition, three water-soluble components with the characteristics of albumin, alpha-amylase and secretory IgA were seen. The minor gland secretions had an amino acid profile different from those of the major salivary glands and contained higher proportions of carbohydrate. Only one lipid component, with the characteristics of a polar lipid, was seen. Hexuronic acids were not detected in either secretion, whereas both contained sulphate. It would appear that the minor mucous glands contribute to the content of mucosubstances in whole saliva, whereas their content of water-soluble material is negligible in this respect.