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Biomedical subjects

R L Gregory

Publications and source records attributed to R L Gregory.

At least 127 records · Page 7Linked to original sources
PubMed1984

Function of anti-Streptococcus mutans antibodies: anti-ribosomal antibodies inhibit acid production, growth, and glucose phosphotransferase activity.

Antibodies induced in sera and saliva of rats and rabbits immunized with ribosomal preparations from Streptococcus mutans 6715 inhibited transport of glucose by the phosphotransferase system by greater than 60%, acid production from sucrose by greater than 95%, and growth of the homologous S. mutans by greater than 59%. Inhibition of growth and acid production by immune sera and saliva were abrogated by prior adsorption with S. mutans 6715 whole cells, glucosyltransferase, lipoteichoic acid, or alpha 1-6 or alpha 1-3 dextran. These results indicate that antibodies induced to an S. mutans ribosomal preparation react with cell surface determinants and suggest that the antibodies inhibit sucrose-induced acid formation and growth of virulent S. mutans by neutralizing the glucose-phosphotransferase system.

Animals↗
PubMed1984

Lack of cross-reactivity of antibodies to ribosomal preparations from Streptococcus mutans with human heart and kidney antigens.

Previous studies have suggested that sera from animals immunized with whole Streptococcus mutans cells may cross-react with human and monkey heart sarcolemmal tissues. In the present study, sera and saliva from rats and rabbits immunized peripherally with ribosomal preparations from S. mutans 6715 (serotype g) or GS-5 (serotype c) were examined for their ability to react with normal human heart sarcolemmal and kidney glomerular tissues by using enzyme-linked immunosorbent and immunofluorescence assays. The results showed that antibodies to serotype g and c ribosomal preparations do not react with either the human heart or renal antigens. Sera from mice immunized with human heart tissue and from a patient with a high anti-streptolysin O titer reacted strongly with human heart sarcolemmal and kidney glomerular tissues. These data indicated that ribosomal preparations from S. mutans lack the putative human heart cross-reactive determinant and suggest that the use of an S. mutans ribosomal vaccine against dental caries may not be pathogenic to human heart or renal tissues.

Animals↗
PubMed1984

An assessment of two amplitude-compression hearing aid systems, especially in high ambient noise.

A critical test of the suitability of amplitude compression in hearing aid design must look at the performance of such devices with high levels of background noise. A series of tests was carried out, using both normal and hearing-impaired subjects and word-list test material. The results favour some forms of amplitude compression, even under these critical conditions. However, nonlinear compression ('Carrier Clipping') can reduce the signal-to-noise ratio to unity under adverse conditions. Under these circumstances, such compression impairs performance, though in most situations, it is beneficial.

Amplifiers, Electronic↗
PubMed1983

Detection of antibodies against Streptococcus mutans cell wall contaminating sera against ribosomal fractions.

A modification of the immunoprecipitation technique was developed to precipitate ribosomal proteins from Streptococcus mutans in isoelectric focusing gels. The method was established in order to determine whether the ribosomal immunogen was contaminated with cell surface proteins. Isoelectric focusing was used to separate the proteins into bands in the gel and various antisera utilized to precipitate the antigens. Electrophoresis of the ribosomal preparation produced 19 protein bands. A rat antiserum raised against the preparation reacted with 8 of these bands and an aliquot of the same antiserum which had been adsorbed with whole S. mutans cells reacted with only 6 bands. This procedure allowed us to detect contamination of the ribosomal preparation with cell surface antigens. The method may be used to detect contamination with cell surface antigens in many different subcellular preparations.

Animals↗
PubMed1983

Oral adjuvants enhance IgA responses to Streptococcus mutans.

The induction of immune responses to orally-administered trinitrophenyl (TNP)-haptenated Streptococcus mutans or its cell wall components and enhancement of immune responses with oral adjuvants has been studied in high IgA responsive C3H/HeJ mice and in gnotobiotic rats. Gastric intubation of TNP-S. mutans to LPS non-responsive C3H/HeJ or syngeneic, LPS responsive C3H/HeN mice induced IgA responses as determined by measuring splenic plaque-forming cell (PFC) responses and IgA anti-TNP antibodies in serum, saliva, and urine. Higher IgA responses always occurred in C3H/HeJ mice given oral S. mutans antigen than similarly treated C3H/HeN animals. Oral administration of the adjuvants concanavalin A or S. mutans cell wall peptidoglycan (PG) with antigen resulted in augmented IgA responses, especially in C3H/HeJ mice. On the other hand, oral administration of muramyl dipeptide (MDP) with antigen boosted anti-TNP responses in C3H/HeN, but not in C3H/HeJ, mice. Gnotobiotic rats given S. mutans whole cells (WC) or purified cell walls (CW) by the oral route exhibited a salivary IgA immune response which was potentiated greater than twofold when antigen was given with PG or MDP. In other studies, S. mutans WC or CW antigen in water-oil-water (W/O/W) emulsion or liposomes was administered by gastric intubation to rats. Significant salivary IgA responses were induced with these antigen-adjuvant preparations. Although rats given S. mutans WC or CW were protected from S. mutans challenge, the greatest degree of caries immunity was obtained in animals which received antigen and adjuvant and which exhibited significant salivary IgA antibody levels. In preliminary studies, it was observed that local injection of rats in the salivary gland region with a ribosomal preparation from S. mutans resulted in a significant salivary IgA response and caries immunity. The potential for soluble and lipid carrier adjuvants in oral vaccines for induction of protective antibodies to S. mutans is discussed.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Effective immunity to dental caries: protection of gnotobiotic rats by local immunization with a ribosomal preparation from Streptococcus mutans.

A ribosomal preparation from Streptococcus mutans 6715 was characterized for its ability to induce an immune response in gnotobiotic rats which was protective against S. mutans-induced dental caries. Animals injected in the salivary gland region with the S. mutans ribosomal vaccine developed significantly higher (P less than 0.01) salivary IgA and serum IgG antibody activities against whole S. mutans cells and ribosomal preparations than nonimmunized rats. Vaccinated animals had significantly lower (67%; P less than 0.01) levels of S. mutans adherent to their molar surfaces than the control rats after infection with the homologous, cariogenic S. mutans. The immunized animals had significantly fewer (P less than 0.01) carious lesions on their buccal, sulcal, and proximal molar surfaces than the nonimmunized rats following challenge with the virulent organism. Animals injected with the ribosomal preparation developed salivary IgA and IgG antibodies with specificities to various cell surface-associated antigens such as lipoteichoic acid and glucosyltransferase, suggesting that the observed protection may be due to antibodies against cell surface contaminants of the ribosomal vaccine. These results are the first demonstration that a ribosomal preparation from S. mutans protected rats from caries formation after challenge with the homologous, virulent S. mutans.

Animals↗
PubMed1983

Analysis of cell wall and membrane contamination of ribosomal preparations from Streptococcus mutans.

A ribosomal preparation from a cariogenic strain of Streptococcus mutans was examined for cell wall and membrane contamination. A biochemical characterization established that the preparation contained 61.0% RNA and 39.0% protein. Carbohydrate was not detected by phenol-sulfuric acid or methyl pentose assays. Glucosyltransferase and D-succinate dehydrogenase, which are cell wall- and membrane-associated enzymes, respectively, were not found. However, D-lactate dehydrogenase, another membrane-associated enzyme, was present in the preparation. A comparison of two-dimensional gel electropherograms of a mixture of cell walls and membranes and the S. mutans ribosomal preparation revealed contamination of the latter sample with at least six cell wall- or membrane-associated proteins. Adsorption of a rabbit antiserum raised against the ribosomal preparation with whole S. mutans cells abrogated antibodies directed against at least two proteins from the ribosomal preparation. Immunodiffusion plates showed reactivity of this antiserum against preparations of purified lipoteichoic acid from Streptococcus pyogenes and S. mutans. Adsorption of rat and rabbit antisera against the ribosomal preparation with the cell wall-derived materials glucosyltransferase, lipoteichoic acid, glucan, and a Rantz-Randall extract reduced the concentration of antibodies against the ribosomes by as much as 10-fold. These data indicated that the preparation was contaminated with at least six cell wall proteins, one cell membrane-associated enzyme, and lipoteichoic acid.

Bacterial Proteins↗
PubMed1982

Humoral and cell-mediated responses to a ribosomal preparation from Streptococcus mutans.

Streptococcus mutans 6715 ribosomes disrupted in a Braun homogenizer were isolated in sodium dodecyl sulfate by differential centrifugation. This preparation contained 80% RNA and 20% protein, and carbohydrate was not detected by phenol-sulfuric acid and methyl pentose assays. The sedimentation coefficient of the ribosomes was 70S. After dialysis in 0.01 M phosphate buffer containing 10(-4) M MgCl2, the ribosomes dissociated into 54S and 32S particles. Leukocytes from rabbits immunized intramuscularly with the ribosomal preparation showed transformation and migration indices of 13.0 and 0.71, which were significantly different (P less than 0.05) from the respective indices of 0.9 and 0.98 in nonimmunized animals. Hyperimmune serum from these rabbits agglutinated representative Formalin-killed strains of all seven serotypes of S. mutans, inhibited adherence of live S. mutans 6715 to glass, and agglutinated S. mutans 6715 ribosomes adsorbed upon erythrocytes. These findings suggested that animals immunized with S. mutans ribosomes may be protected from caries caused by any of the seven serotypes of this organism.

Agglutination Tests↗