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Biomedical subjects

G Embery

Publications and source records attributed to G Embery.

At least 19 recordsLinked to original sources
PubMed1992

Adsorption of glycosaminoglycans to commercially pure titanium.

Aqueous solutions of the glycosaminoglycans (GAG), chondroitin-4-sulphate (C4S), chondroitin-6-sulphate (C6S), heparan sulphate (HS) and hyaluronan (HY) were reacted with 5 g samples of both native and calcium-treated titanium powder (99.5% pure) for 0-48 h in 10 ml volume at 37 degrees C. Residual GAG was detected in the supernatant following recovery of the TiO2-GAG complex by centrifugation (5000 g for 1 min) as hexuronic acid using the carbazole tetraborate method of Bitter and Muir. No adsorption on to native TiO2 was evident. In contrast, prior treatment of TiO2 with calcium produced a significant adsorption of C4S to a maximum of 60 micrograms of GAG per gram Ti. Only trace amounts of C6S, HS and hyaluronan interacted in the same way. Further evidence of interaction was obtained following the liberation of bound GAG from the TiO2-Ca-GAG complex with EDTA and identification using cellulose acetate electrophoresis. These findings suggest that calcium ions are required for adsorption of GAG to TiO2 which is mediated through the anionic determinants of the GAG surface and that the special configuration of C4S, the predominant chondroitin sulphate isomer found in alveolar bone, is important in the adsorption process. The implication of these findings in relation to the interaction between bone and titanium implants is discussed.

Adsorption↗
PubMed1991

Structural characterization of human alveolar bone proteoglycans.

Proteoglycans were extracted from EDTA-demineralized human alveolar bone under dissociative conditions using 4 M guanidinium chloride in the presence of protease inhibitors. The extract was further purified by anion-exchange chromatography on DEAE-Sephacel, using a step-wise salt gradient. The proteoglycan-rich fraction was analysed for carbohydrate, protein and amino acid composition and molecular size by SDS-PAGE. Glycosaminoglycan content was determined by cellulose acetate electrophoresis after proteolysis. The sulphate isomers of the glycosaminoglycans were confirmed by Fourier-transformed infra-red spectroscopy. Two chondroitin sulphate-proteoglycan species were identified with molecular weights of 79 and 55-65 kDa, respectively. The core proteins had molecular weights of 49 kDa for both proteoglycans, with the amino acid content rich in glycine, leucine, glutamate and aspartate. The chondroitin sulphate chains were mainly as the 4-sulphate isomer forms although low but detectable amounts of 6-sulphate isomer were also present.

Alveolar Process↗
PubMed1991

Monitoring of Tübingen endosseous dental implants by glycosaminoglycans analysis of gingival crevicular fluid.

Glycosaminoglycans (GAG) in gingival crevicular fluid (GCF) samples were determined by cellulose acetate electrophoresis and densitometric scanning. Two GAG bands, hyaluronic acid and chondroitin-4-sulphate (C4S), were detected in GCF from implants, similar to the profile from teeth. High GCF volumes and GAG contents, notably C4S, may reflect postoperative alveolar bone responses, particularly resorption, at different stages of healing and function of successful implants. They may also indicate adverse tissue changes in failing implants. A comparison of crowned implants and matched teeth suggests that the periodontal ligament contributes to the GCF GAG profile. This may be a useful laboratory method of monitoring implants to detect adverse tissue responses at an early stage.

Adolescent↗
PubMed1989

Glycosaminoglycans of human alveolar bone.

Bone proteoglycan was extracted and the glycosaminoglycan (GAG) components identified. Chondroitin-4-sulphate was the major GAG detected and represented 93.8% of the total GAG extracted. In addition, hyaluronic acid (1.3%), dermatan sulphate (3.1%) and heparan sulphate (1.8%) were identified as minor constituents.

Alveolar Process↗
PubMed1989

Structural probe analysis on the attachment of salivary glycoproteins to hydroxyapatite using Fourier-transformed infrared spectroscopy.

The mechanisms of interaction between a salivary glycoprotein and hydroxyapatite has been studied using Fourier-transformed infrared spectroscopy. The spectra of the reacted mixtures showed evidence of change at 1,230-1,250 cm-1 due to the S = O stretching vibrations of the ester sulphate groups and at 775 and 828 cm-1 attributed to sulphate groups in the 6-position of N-acetylgalactosamine. Evidence of amide change in the regions of 1,670 and 1,550 cm-1 is also apparent due to involvement of the polypeptide region. It is proposed that the exposed parts of the protein core are involved in the attachment of the glycoprotein to hydroxyapatite with the main interactive residues being the sulphate groups present on the carbohydrate apo-protein moiety. The results are considered of value in relation to mechanisms involved in the coating of exposed apatite surfaces during the formation of acquired enamel pellicle.

Absorption↗
PubMed1989

The hydroxyapatite-binding regions of a rat salivary glycoprotein.

The regions of a salivary sulphated glycoprotein which are involved in its attachment to hydroxyapatite (Biogel HTP) have been characterised. The sulphated glycoprotein, a 35S-labelled preparation from mixed palatal and buccal minor gland secretions of the rat was bound onto hydroxyapatite and the resultant glycoprotein-hydroxyapatite complex was sequentially digested with pronase E and alpha-L-fucosidase, a treatment which released 86.8% +/- 1.7% of the radioactivity of the initially bound glycoprotein. The fragments which remained attached to the hydroxyapatite after enzymic digestion were fractionated on Sephadex G-25 and analysed for carbohydrate and amino acid components. A range of amino acids were detected which could reflect both glycosylated and non-glycosylated-binding regions. Sialic acid, although considered to be involved in the attachment process was not detected in any of the fragments remaining after enzymic digestion, a finding which provides indirect evidence that the enzymically liberated products do not subsequently re-attach to the hydroxyapatite surface. The notable feature of the fractions with average Mr estimated at 1000 or less is the high proportion of N-acetylhexosamine and N-acetylgalactosamine. It is apparent that the hexosamine residues, which normally bear the ester sulphate moieties of sulphated glycoproteins, play an important role in the attachment of sulphated glycoproteins to hydroxyapatite.

Amino Acids↗
PubMed1988

Glycosaminoglycans in human gingival crevicular fluid during orthodontic movement.

Glycosaminoglycans (GAG) in gingival crevicular fluid (GCF) were investigated by cellulose acetate electrophoresis of simultaneously collected samples from the mesial and distal surfaces of teeth in 3 groups of young persons. In a control group, which had not undergone orthodontic treatment, a major band of hyaluronic acid (HA) and a minor band of chondroitin sulphate (CS) were present. No differences in the mean content of either GAG between the mesial and distal surfaces were detected. From teeth undergoing movement by fixed appliances (active group), a raised mean level of CS was present in GCF from the surface towards which movement was directed. Teeth held passively by an appliance following cessation of active movement (retention group) showed raised levels of CS at mesial and distal surfaces. A heparan sulphate-like GAG was commonly present in this group only. No significant increase in the levels of HA were detected at the mesial and distal surfaces of either the active or the retention groups, despite increased GCF flow rates unassociated with more severe gingival inflammation. The GAG composition of GCF, particularly CS, appears to reflect changes occurring in the deeper periodontal tissues of alveolar bone and periodontal ligament during orthodontic treatment.

Adolescent↗
PubMed1988

The glycosaminoglycan constituents of alveolar and basal bone of the rabbit.

Proteoglycan was extracted from alveolar and basal bone of New Zealand White rabbits using a sequential extraction procedure. Proteoglycans not associated with the bone mineral represented 1% of the total organic matrix whereas proteoglycans associated with the mineral represented 20% of the alveolar organic matrix and 12% of the basal organic matrix. Chondroitin-4-sulphate and keratan sulphate were identified in both alveolar and basal bone following protease treatment of the proteoglycan extracts and enzymic digestion with chondroitinase AC, ABC and keratanase. Differences were observed in the percentage of each glycosaminoglycan (GAG) in the total organic matrix. In alveolar bone samples, keratan sulphate and chondroitin-4-sulphate is present in equal proportions. In basal bone chondroitin-4-sulphate represents approximately half the value found in alveolar bone and keratan sulphate about a quarter. The extracts were examined by gel filtration on Sepharose 4B under associative conditions. The 280 nm absorbance profiles of proteoglycan from alveolar and basal bone were essentially similar with three main peaks evident, including molecular weight material in excess of 2 X 10(6). The bulk of the bone GAG appeared in the medium molecular weight range with trace amounts in lower molecular weight fractions.

Alveolar Process↗
PubMed1988

Studies on the interaction between sodium lauryl sulfate and hydroxyapatite using Fourier transformed infrared spectroscopy.

The interaction between sodium lauryl sulfate (SLS) and hydroxyapatite (HA) was studied by using Fourier transformed infrared spectroscopy. The adsorption isotherms to HA and enamel were also established. The results obtained by infrared spectroscopy demonstrated that there was no direct evidence of hydrocarbon interactions between the two compounds since the (CH2)n signal remained unchanged. In contrast reacted mixtures of SLS and HA showed a disappearance of absorption bands between 1220 and 1260 due to stretching of S = 0 bonds. This indicates that the sulfate groups interacted with the HA-crystal surface. Treatment of HA-powder and dental enamel with different concentrations of 35S-labelled SLS showed saturation patterns with a maximum of 3.5 micrograms/mg HA and a maximum of 0.68 microgram/mm2 enamel. This study showed that SLS binds to HA through the sulphate groups and that the binding is most likely electrostatic in nature; the interaction mediated between SLS molecules and calcium ions distributed in the hydration layer of the enamel.

Adsorption↗
PubMed1987

Hyaluronic acid and hyaluronidase activity in gingival exudate from sites of acute ulcerative gingivitis in man.

Gingival exudates from sites of acute ulcerative gingivitis (AUG) and chronic gingivitis (CG) in adults were investigated by cellulose-acetate electrophoresis for the hyaluronic acid (HA) content and assayed for the levels of HA-degrading enzymes. HA was the only glycosaminoglycan (GAG) in gingival exudate from CG sites. HA was not detected at untreated AUG sites but was evident, at increasing levels, after two and seven days of effective antibacterial treatment. In AUG exudates, the total HA-degrading enzyme activity, of bacterial origin, decreased to approx. 30 and 10 per cent of the high initial levels after two and seven days of treatment respectively, to that level found at sites of CG. The specific activity of HA-degrading enzyme of lysosomal origin was low initially and increased with treatment to a level comparable to CG. The notable absence of HA from gingival exudate from sites of untreated AUG thus appears to result from the increased levels of bacterial hyaluronidase. Electrophoresis of gingival exudate may be an indirect method of monitoring the rate of response of AUG to different antibacterial treatments.

Acute Disease↗
PubMed1987

Biochemical changes in periodontal ligament ground substance associated with short-term intrusive loadings in adult monkeys (Macaca Fascicularis).

Proteoglycan-like fractions (PG) were isolated from the ligaments of teeth undergoing various degrees of intrusive loadings. The PG were characterized by their molecular-size profiles on Sepharose 4B, the presence of uronic acid in the separated fractions and by the electrophoretic detection of constituent glycosaminoglycans including heparan sulphate, hyaluronic acid, dermatan sulphate and chondroitin-4-sulphate. The high molecular-weight fraction, peak i (estimated minimum size, 2 X 10(6) daltons) of the normal-functioning (stressed) ligament was reduced approx. 70 per cent, compared with ligament undisturbed for 3 h. There was a decrease in peak-i size between 0.25 and 1 N loadings of approx. 72 per cent. The 4 N loadings produced a further decrease followed by an increase during a 3 h undisturbed recovery phase. Thus changes in the chemistry and properties of the ground-substance components of the periodontal ligament could partly explain changes in tooth mobility.

Animals↗
PubMed1987

Isolation, chemical and biological characterization of sulphated glycoproteins synthesized by rat buccal and palatal minor salivary glands in vivo and in vitro.

35S-labelled sulphated glycoproteins (SGP) were isolated from these glands after the incorporation of radiosulphate in vivo and in vitro by fractionation of tissue and medium extracts on Sepharose 4B and partial purification by DEAE-Sephacel anion exchange chromatography. Fractions were assessed for purity by SDS-PAGE and by cellulose-acetate electrophoresis. Molecular weights ranged from 34,000 to 5 X 10(6). It was notable that the molecular size of SGP from the in vitro media was generally lower than from the corresponding tissue fractions, particularly for the palatal samples. The fractions were heterogeneous and contained no sulphated glycosaminoglycans; they had high levels of aspartic acid, glutamic acid, threonine and serine, but there was no major difference in amino-acid composition between them. Carbohydrate analysis indicated typical components associated with sulphated glycoproteins, including fucose, galactose, glucose, mannose, N-acetylgalactosamine, N-acetylglucosamine and N-acetylneuraminic acid. Protein:carbohydrate ratios ranged from 0.1:1.0-3.5:1.0 and ester sulphate from 0.8 to 16.2 per cent. All fractions exhibited blood-group A reactivity and aggregated Streptococcus sanguis NCTC 7864; several fractions interacted similarly with Streptococcus mutans OMZ61.

ABO Blood-Group System↗
PubMed1986

Studies on the organic polyanionic constituents of human acquired dental pellicle.

Extracts of acquired dental pellicle were obtained by a two-step procedure. Pellicle formed on cleaned teeth was first extracted using 2 M CaCl2, and the remainder then removed by scraping followed by solubilization in 5 per cent (w/v) EDTA. The 2 M CaCl2 extract contained high-molecular-weight glycoprotein which was present in only trace amounts in the EDTA extract. Cellulose-acetate electrophoresis of both extracts revealed low-molecular weight protein which contained phosphate. This protein tentatively identified as a phosphoprotein, disappeared as the pellicle matured. The findings have implications in relation to early bacterial colonization of the tooth surface.

Dental Deposits↗
PubMed1985

Glycosaminoglycans in human gingival crevicular fluid as indicators of active periodontal disease.

The glycosaminoglycans (GAG) in gingival crevicular fluid (GCF) were investigated by cellulose-acetate electrophoresis of samples from individual sites of defined conditions variously affecting the tissues of the periodontium. The non-sulphated GAG, hyaluronic acid, was present in all samples and was the only major band from sites of chronic gingivitis. An additional sulphated GAG band identified by enzymic digestions as chondroitin-4-sulphate, was detected in GCF from sites of untreated-advanced periodontitis. Initial samples from sites of early periodontitis and juvenile periodontitis yielded a similar additional band which was not detected, however, in samples collected after either surgery to eliminate deep pockets or daily subgingival irrigation with a chlorhexidine solution. Sulphated GAG was also present in fluid from the control situations, i.e. of teeth either undergoing orthodontic movement or showing evidence of trauma from occlusion, and from healing tooth-extraction wounds. Thus the presence of such a component in GCF correlates with those clinical conditions in which degradative changes are occurring in the deeper-periodontal tissues. The electrophoretic profile of GAG in a sample of GCF may be a sensitive laboratory method of indicating active phases of destructive periodontal disease at individual sites.

Chronic Disease↗
PubMed1985

Glycosaminoglycan-depolymerizing enzymes produced by anaerobic bacteria isolated from the human mouth.

A number of obligately anaerobic bacteria, some implicated in periodontal disease, were screened for their ability to produce enzymes capable of degrading hyaluronic acid and chondroitin-4-sulphate. Two screening methods were used following anaerobic incubation at 37 degrees C for 7 days. One involved incorporating the respective substrates and bovine-serum albumin into agar plates and, after incubation, flooding the plates with 2 M acetic acid. Clear zones were produced around colonies which produced enzymes capable of depolymerizing the substrates. The second was a sensitive spectrophotometric procedure based on the ability of certain bacteria to produce eliminase enzymes, which degrade the substrates to unsaturated products having a characteristic u.v. absorption at 232 nm. Strains of Bacteroides gingivalis and Bacteroides melaninogenicus degraded both substrates whereas Bacteroides asaccharolyticus degraded neither substrate by either method. Some bacteria gave negative results with the plate method whereas the more sensitive spectrophotometric assay proved positive. The number of anaerobic bacteria capable of degrading hyaluronic acid and chondroitin-4-sulphate in vitro may therefore have been underestimated in previous studies.

Bacteria, Anaerobic↗