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Biomedical subjects

D Orstavik

Publications and source records attributed to D Orstavik.

81 records · Page 5Linked to original sources
PubMed1977

Sorption of Streptococcus faecium to glass.

A method has been developed by which to study the sorption of Streptococcus faecium to soda-lime cover glasses. Conditions were chosen to minimize the influence on sorption of bacterial polymer production, passive sorption being studied rather than attachment mediated by metabolic activities. Sorption of S. faecium increased with increasing temperature (to 50 degrees C), time, and cell concentration, but equilibrium apparently was not reached even after incubation for 8 hours or at a cell concentration of 3 X 10(10) per ml. Sorption increased with solute molarity up to 0.1 M concentration of NaCl and KCl, indicating an effect of the electrical double layers on the apposition of cells to the glass surface. Desorption of bacteria could be obtained after multiple washings of the glasses in buffer or by the action of Tween 80, but not if sorbed bacteria were left in distilled water, various salt solutions, urea, or in suspensions of unlabelled bacteria. It was concluded that sorption occurred as a result of chemical interactions between the glass and the cell surface. Tween 80 at a concentration of 1 per cent inhibited sorption to 26 per cent of buffer controls, 2 M urea was less effective, and 1 M NaCl was without effect. It is suggested that hydrophobic interactions may be of importance in the binding of S. faecium to glass.

Carbonates↗
PubMed1977

Sorption of Streptococci to glass: Effects of macromolecular solutes.

Macromolecular solutes (albumin, concanavalin A, whole saliva, serum) caused impaired sorption of Streptococcus faecium and Streptococcus sanguis to glass. The inhibitory effect resided chiefly with interactions of the solutes with the glass surface. In the case of sorption of S. sanguis to glass in the presence of parotid fluid, the inhibitory effect was counteracted by a specific attachment of S. sanguis cells mediated by some component(s) of the parotid fluid. Agglutination of the test organisms was in general accompanied by inhibition of sorption. However, when small or unstable aggregates were formed, the number of cells adhering on the glass surface was increased. The findings are discussed with reference to the colonization of teeth by oral bacteria.

Agglutination Tests↗
PubMed1976

In vitro attachment of Streptococcus sanguis to dental crown and bridge cements.

The ability of a common dental plaque bacterium, Streptococcus sanguis, to adhere to dental crown and bridge cements in vitro was investigated. Cylindrical blocks of five different commercial brands of cement, with and without acquired pellicles, were indubated with buffer suspensions of S. sanguis for 1 h. Attached bacteria were counted under the microscope. S. sanguis had particularly high affinity for uncoated resin cement. In contrast, the carboxylate cement tested was a poor substrate for the adherence of this bacterium. The other cement types (zinc phosphate, zinc oxide and silico-phosphate) had intermediary qualities as adhering surfaces. The presence of an acquired pellicle, obtained by pretreatment with saliva, influenced the initial adherence of bacteria to cement in vitro. On the resin cement a salivary pellicle strongly suppressed the bacterial adhesion. For the zinc phosphate, zinc oxide and silico-phosphate cements a pellicle slightly enhanced the attachment of S. sanguis. On the carboxylate cement only few organisms attached also after pretreatment with saliva.

Cell Count↗
PubMed1974

In vitro attachment of streptococci to the tooth surface.

The ability of Streptococcus strains to adhere to the tooth surface in vitro was investigated. Polished enamel slabs, with and without acquired pellicles, were incubated with buffer suspensions of oral streptococci, and attached bacteria were counted under a microscope using incident light. Low numbers of bacteria adhered to uncoated enamel; the presence of an acquired pellicle significantly enhanced the attachment of all strains tested. The adherence of Streptococcus sanguis was significantly greater than that of Streptococcus salivarius, and both of these strains adhered in greater numbers than did Streptococcus mutans. When bacteria were suspended in whole saliva, the adherence of S. salivarius and S. mutans was inhibited, whereas the adherence of S. sanguis was enhanced in some experiments and inhibited in others. The adherence of S. sanguis and S. salivarius was consistently inhibited by parotid fluid; this inhibitory effect persisted after thorough washing and resonication of the bacterial cells. Incubation in oral fluids was associated with the attachment of bacterial clumps to the pellicle, and parallel investigation revealed agglutination of S. sanguis and S. salivarius by whole saliva and, in particular, parotid fluid. The results are discussed in terms of surface microecology, and are related to the development of dental plaque.

Agglutination Tests↗
PubMedDate not supplied

Serum antibodies to plaque bacteria in subjects with dental caries and gingivitis.

Correlations were sought between indices of gingival inflammation and dental caries experience and serum antibody titers to five species of oral bacteria. The material comprised 53 young adult males. A statistically significant, negative correlation was observed between the antibody titer to a pool of Veillonella strains and dental caries experience. Multiple regression analyses failed to reveal significant associations between periodontal disease and serum antibody titers. However, the data suggested a combined association of the titers to the strains of Veillonella and a strain of Fusobacterium with the periodontal index.

Adult↗