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Biomedical subjects

J M Tanzer

Publications and source records attributed to J M Tanzer.

At least 73 records · Page 4Linked to original sources
PubMed1977

In vitro evaluation of three iodine-containing compounds as antiplaque agents.

The antibacterial activity of three iodine-containing compounds was determined for strains of four dental plaque-forming microorganisms, using an in vitro preclinical plaque model system. Solutions of inorganic iodine, povidone-iodine, and Wescodyne were tested for antiplaque activity against preformed plaques of a number of strains of Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus, and Actinomyces naeslundii. Solutions of inorganic iodine were more effective as antiplaque agents, with respect to minimal bactericidal concentration and time and frequency of treatments, than solutions of Wescodyne and povidone-iodine. Inorganic iodine appeared to be particularly effective against the most cariogenic (S. mutans) and periodontopathic (A. viscosus) organisms while allowing survival of the least orally pathogenic plaque-forming microorganism (S. sanguis). It is suggested that topical application of solutions of inorganic iodine may be useful in controlling dental caries and actinomyces-associated periodontal disease.

Actinomyces↗
PubMed1977

Structural requirements of guanide, biguanide, and bisbiguanide agents for antiplaque activity.

The bactericidal efficacy of 16 guanide, biguanide, and bisbiguanide agents was studied in vitro against intact preformed plaques of four oral (plaque-forming) microorganisms: Streptococcus mutans, S. sanguis, Actinomyces viscosus, and A. naeslundii. The activities of these agents were examined in relation to their molecular configurations. These studies indicated that the bis- and biguanide configurations are important for efficacy, as is the length of the alkyl side chain. No structural moiety determined efficacy by itself. Furthermore, the activities of these agents were studied to determine the minimal conditions (concentration, duration, and frequency) of treatment required for likely clinical efficacy. At least six agents were judged to have equal or greater efficacy than the reference agent, chlorhexidine digluconate. A plaque bactericidal index was derived for the most potent agents, and comparison to the bactericidal properties of chlorhexidine was expressed as a chlorhexidine coefficient.

Actinomyces↗
PubMed1977

Comparative study of invertases of Streptococcus mutans.

Sucrase activity was studied in 13 strains of Streptococcus mutans representing the five Bratthall serotypes. Sucrose-adapted cells have sucrase activity in the 37,000 x g-soluble fraction of all strains. The enzyme was identified as invertase (beta-d-fructofuranoside fructohydrolase; EC 3.2.1.26) because it hydrolyzed the beta-fructofuranoside trisaccharide raffinose, giving fructose and melibiose as its products, and because it hydrolyzed the beta-fructofuranoside dissacharide sucrose, giving equimolar glucose and fructose as its products. Invertases of c and e strains exhibit two activity peaks by molecular exclusion chromatography with molecular weights of 45,000 to 50,000 and about 180,000; those of serotypes a, b, and d strains exhibit only a single component of 45,000 to 50,000 molecular weight. The electrophoretic mobility of invertases is different between the serotypes and the same within them. Inorganic orthophosphate (P(i)) has a weak positive effect on the V(max) of invertases of serotypes c and e cells but a strong positive effect on the invertases of serotype b cells; P(i) has a strong positive effect on the apparent K(m) of the invertases of serotype d cells, but has no effect on the V(max); P(i) has a strong positive effect on both the apparent K(m) and V(max) of the invertases of serotype a cells. Thus, the invertases were different between all of the serotypes but similar within the serotypes. These findings support the taxonomic schemes of Coykendall and of Bratthall. It was additionally noted that 37,000 x g-soluble fractions of only serotypes b and c but not serotypes a, d, and e cells have melibiase activity, and it could be deduced that serotype d cells lack an intact raffinose permease system.

Cell-Free System↗
PubMed1977

Identification, separation, and preliminary characterization of invertase and beta-galactosidase in Actinomyces viscosus.

The initial step of disaccharide dissimilation by Actinomyces viscosus serotype 2 strain M-100 was studied. Sucrase activity was found in the 3,000 X g particulate fraction and the 37,000 X g soluble fraction of the cells, whereas lactase activity was found almost exclusively in the 37,000 X g soluble fraction. Neither sucrase nor lactase activity was appreciable in the culture liquor. Sucrose phosphorylase, alpha-glucosidase, and polysaccharide synthesis activities were not observed in the soluble cell fraction. The sucrase was identified as invertase (EC 3.2.1.26; beta-D-fructofuranoside fructohydrolase). The lactase was identified as beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase). The enzymes in the 37,000 X g soluble fraction were separable by diethylamino-ethyl-cellulose chromatography, giving one beta-galactosidase peak and one major and one minor invertase peak. Acrylamide gel electrophoresis showed different electrophoretic mobilities of the enzymes. The molecular weight of the beta-galactosidase is about 4.2 X 10(5) and that of invertase is about 8.6 X 10(4). The beta-galactosidase has a Km for lactose of about 6 mM and a pH optimum between pH 6.0 and 6.5. The major invertase component has a Km for sucrose of about 71 mM and a pH optimum between pH 5.8 and 6.3.

Actinomyces↗
PubMed1977

Regulation of invertase of Actinomyces viscosus.

The regulation of diethylaminoethyl-partially purified invertase (EC 3.2.1.26; beta-D-fructofuranoside fructohydrolase) from the 37,000 X g-soluble intracellular fluid of Actinomyces viscosus serotype 2 strain M-100 was studied. Glycolytic intermediates, mono-, di-, and triphosphate nucleotides, inorganic phosphate, and various divalent cations were tested for regulatory effects. Fructose-6-phosphate (F6P) and fructose-1,6-diphosphate (FDP) were found to act as noncompetitive inhibitors of invertase. The Ki values for F6P and FDP were found to be 3.4 and 5.1 mM, respectively. The Hill coefficient for sucrose was 1.03 and remained unchanged in the presence of varying amounts of F6P or FDP.

Actinomyces↗
PubMed1974

Dissociation of plaque formation from glucan-induced agglutination in mutants of Streptococcus mutans.

The traits adhesion and cohesion are manifested in Streptococcus mutans by in vitro plaque formation and glucan-mediated agglutination and have been dissociated in mutants of this caries-associated microbe. In these mutants, which differ from each other in colonial morphology, we have observed a consistent loss of ability to form adhesive microbial deposits (plaque) on wires, but only a minimal alteration from the wild type in ability to agglutinate into macroscopic clumps in the presence of exogenous glucans or sucrose. Also, when these mutants were cultured in sucrose-containing medium, there was an increase in the synthesis of water-soluble, extracellular glucans and a decrease in the synthesis of alkali-soluble, cell-associated glucans. Based on these findings, it appears (i) that in vitro plaque formation and agglutination are distinct and dissociable traits, and (ii) that adhesion but not agglutination appears related to the synthesis of alkali-soluble, cell-associated glucans.

Agglutination↗
PubMed1974

Diminished virulence of glucan synthesis-defective mutants of Streptococcus mutans.

The virulence of cell surface-associated, glucan synthesis-defective mutants of Streptococcus mutans strain 6715-13 was studied. Representatives from three groups of such mutants were tested for their pathogenicity in conventionalized, specific pathogen-free rats and gnotobiotic rats. The mutants differ from the wild-type strain in that each failed to form plaque on the smooth surfaces of the teeth and to cause smooth surface caries. Although the ability to form cell surface-associated glucans was not a strict requirement for the expression of virulence in the sulci of the teeth, it augmented virulence at such sites. However, the ability to form cell surface-associated glucans and to adhere to the teeth was clearly not the sole determinant of virulence.

Animals↗
PubMed1974

Ultrastructure of Mutants of Streptococcus mutans with Reference to Agglutination, Adhesion, and Extracellular Polysaccharide.

An electron microscopic study of S. mutans 6715-13 wild type and representatives of three distinct classes of glucan synthesis-defective mutants (which fail to form adherent microbial plaques but agglutinate normally in the presence of exogenous glucans) disclosed the presence of two sucrose-dependent, glucanase-sensitive, extracellular components. In the wild type, these extracellular glucans had predominantly fibrillar (with some globular) morphologies. However, in the mutant strains, there was a consistent reduction in or loss of the fibrillar components and dramatic increases in globular forms. A cell surface-associated fuzzy coat was consistently seen, and it was neither sucrose-dependent nor glucanase-sensitive. The data indicated that in vitro and in vivo adhesion and virulence at smooth tooth surfaces (all these properties dramatically reduced in the mutants) were causally and functionally related to the extracellular, fibrillar, glucan component, whereas in vitro glucan-mediated agglutination may be related to the cell-associated surface fuzzy coat.

Journal Article↗
PubMed1973

Identification, preliminary characterization, and evidence for regulation of invertase in Streptococcus mutans.

Sucrose dissimilation was studied in five strains of Streptococcus mutans. Glucose-adapted strain SL-1 makes acid more slowly from sucrose than from glucose; glucose-adapted strain SL-1 gives diauxie growth kinetics in broth containing limiting amounts of both glucose and sucrose. Thus, at least part of the sucrose dissimilative system appears inducible. Sucrase activity was identified in the 37,000 x g soluble cell fraction of five strains. Its intracellular location implies the presence of sucrose permease. The specific activity of the sucrase is higher in sucrose-adapted cells than in cells adapted to glucose or other sugars, further suggesting its inducibility. The enzyme from strain SL-1 was partially purified by diethylaminoethyl-cellulose chromatography and shown to be a single molecule with a molecular weight of about 48,000. The partially purified enzyme is specific for sucrose and produces equimolar glucose and fructose. Since it degrades raffinose, but not melezitose or other alpha-glucosides, it is an invertase. The invertase has a relatively high K(m) for its substrate and a pH optimum of 5.5 to 6.2. It is activated by inorganic orthophosphate (P(i)), P(i) functioning as a positive effector. Arsenate can substitute for phosphate. Neither the crude cell-free extract nor the partially purified enzyme preparations has detectable sucrose phosphorylase activity. A possible potent role of the invertase in the regulation of sucrose carbon flow in S. mutans is discussed.

Acids↗
PubMed1972

Method for preclinical evaluation of antiplaque agents.

A preclinical method for the evaluation of antibacterial agents for use against dental plaques associated with caries and periodontal disease is proposed. The method is applicable to screening agents and to defining, in vitro, the minimal conditions required for maximal antiplaque effect. As a model of antiplaque agents, chlorhexidine was assessed in vitro against preformed plaques of microorganisms conducive to dental caries and periodontal disease. The agent was bactericidal to plaques of nine strains of Streptococcus mutans and one strain of Actinomyces viscosus when used in a single treatment for 20 min at 2 x 10(-1)%, in two 2-min treatments on the same day, or in daily 2-min treatments at this same concentration. Using the last of these experimental conditions, we then tested chlorhexidine in vivo by topical application to the maxillary teeth of infected hamsters and found it to be effective in controlling plaques of S. mutans and A. viscosus.

Animals↗