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Biomedical subjects

J van Houte

Publications and source records attributed to J van Houte.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effect of oral nutrient limitation of gnotobiotic rats on acidogenic properties of dental plaque formed by oral streptococci.

The acid production rate of dental plaque, formed by different streptococci in gnotobiotic rats fed a high sucrose diet or starved for seven or eight days, was determined in vitro. Starvation had no appreciable effect on acid production. This supports the idea that the small pH-lowering ability of plaque of caries-free or stomach tube-fed people in whom exposure of the teeth to fermentable carbohydrate is relatively low or negligible results from a change in the bacterial population rather than a change in the rate of acid production by an unaltered flora.

Animals↗
PubMed1983

Enamel demineralization by mouthrinses containing different concentrations of sucrose.

Intra-oral enamel demineralization tests, involving rinsing with sucrose solutions (5, 1, 0.5, or 0.3%) at varying frequencies during a 1.5-hour period, showed that demineralization was a function of the total sugar dose (frequency of rinsing times concentration). Two rinses with a 5% solution caused demineralization, nine rinses were needed in the case of a 0.5% solution, and none occurred after nine rinses with a 0.3% solution. Remineralization was also observed and apparently occurred after exhaustion of the sucrose supply.

Adult↗
PubMed1983

Enamel demineralization potential of dietary carbohydrates.

Mouthrinses with 5% solutions of different sugars were tested for their demineralizing effect on blocks of bovine enamel covered with a layer of S. mutans cells and carried in a palatal prosthesis. The extent of demineralization, as measured by the permeability of the enamel to iodide, was similar for fructose, glucose, and sucrose, less for maltose and lactose, and least for galactose.

Adult↗
PubMed1982

Oral flora of children with "nursing bottle caries".

S. mutans averaged about 60% of the total cultivable flora of dental plaque obtained from caries lesions, white spot margins of these lesions, or clinically-sound areas of upper anterior teeth, and averaged about 27% in plaque from mostly clinically-sound areas of posterior teeth of six children with nursing bottle caries; its concentrations in saliva averaged about 10% of the total cultivable flora. Nearly all of 107 isolated S. mutans strains belonged to the serotype group c/e/f. The proportion of S. sanguis, in contrast to those of S. mutans, were very low in plaque from upper anterior teeth and higher in plaque from posterior teeth. The proportions of S. salivarius in saliva were unusually low, and this organism was not detected in the saliva of most subjects. Lactobacilli were found in nearly all plaque samples; plaque and carious material from cavities contained higher levels than plaque associated with white spots or clinically-sound tooth surfaces. The findings provide further support for the role of S. mutans in the initiation of human dental caries. In the case of lactobacilli, they support other evidence suggesting only the limited involvement of these organisms in the initiation of caries lesions, but a more extensive role in their progression. In addition, they clearly illustrate the marked effect of diet on the dental plaque flora.

Bottle Feeding↗
PubMed1979

Relationship between host age and susceptibility to oral colonization by Actinomyces viscosus in Sprague-Dawley rats.

The colonization of Actinomyces viscosus strain Ny-1R on the molar teeth of conventional and ex-germfree rats of various ages fed either a high-sucrose diet, a high-glucose diet, or laboratory chow was studied. Conventional rats directly after weaning and up to 30 days of age are less susceptible to experimental infection by strain Ny-1R than are older rats regardless of the test diet. The relationship between host age and susceptibility to infection is also demonstrable in ex-germfree rats fed a high-sucose diet. Host factors responsible for the differences in susceptibility were investigated. The results from these studies do not implicate host antibodies, host indigenous flora, or host saliva. In other studies, it was demonstrated that within the mouths of rats, strain Ny-1R preferentially colonizes in the pits and fissures of the molar teeth rather than on the dorsum of the tongue or on the vestibular mucosa. In short-term experiments, it was found that strain Ny-1R attaches to the first molars of 40-day-old conventional rats to a greater extent than it attaches to the first molars of 20-day-old rats. The differences in attachment and subsequent colonization of strain Ny-1R in 20- and 40-day-old rats may be related to the varying amounts of the reduced enamel epithelium and connective tissue present in the fissures of the molar teeth.

Actinomyces↗
PubMed1978

Antimicrobial effects of N2 in vitro.

The antimicrobial effect of the root canal filling material N2 has been studied in vitro. Pulverized as well as intact set N2 inhibited the growth of the mixed bacterial flora of saliva or pure cultures of S. mutants and A. viscosus on blood agar for at least 100 days. Intact set N2 transferred daily to blood agar inoculated with saliva lost its antimicrobial activity after nine transfers. The antimicrobial effect of N2 against S. mutants was found to be bactericidal. N2 also appeared to possess an antimicrobial "vapor effect".

Actinomyces↗
PubMed1978

Colonization of teeth in humans by Streptococcus mutans as related to its concentration in saliva and host age.

The relationship of the salivary concentration of Streptococcus mutans and host age to the colonization of this organism on erupting teeth was studied in humans. Plaques were obtained from fissures and buccal surfaces of erupting permanent first and second molars of children 6 to 7 and 11 to 14 years old, respectively. In subjects of both age groups with salivary S. mutans concentrations below 5 x 10(2) colony-forming units per ml, the organism was detected on only a few of the tooth surfaces; at concentrations of 5 x 10(2) to 4.9 x 10(4) colony-forming units per ml more than half of the surfaces and at concentrations of 5 x 10(4) colony-forming units per ml or higher most of the surfaces were colonized by S. mutans. The frequency of detection and concentration of S. mutans in plaque as well as its concentration in saliva were higher in the case of the older children. However, when younger and older children with similar salivary S. mutans concentrations were compared, S. mutans was more frequently isolated from plaque from older children only in the case of children with below 5 x 10(2) colony-forming units per ml of saliva. Eleven of the 64 children studied had low or undetectable S. mutans levels in plaque and saliva. The salivary S. mutans levels of the parents of these children were lower than those of parents of a group of children with normal oral S. mutans levels.

Adolescent↗
PubMed1978

Role of colonization in the virulence of Actinomyces viscosus strains T14-Vi and T14-Av.

Germfree rats fed a high-sucrose diet were inoculated with Actinomyces viscosus strain T14-Vi (virulent) or T14-Av (avirulent). The mean recovery of strain T14-Vi from six extracted finely ground molars of rats sacrificed after 90 days was 1.1 x 10(8) colony-forming units (CFU). The mean recovery of strain T14-Av was 5.7 x 10(7) CFU, which was significantly less. Strain T14-Vi caused severe alveolar bone loss, but only minimal bone loss occurred in rats infected with strain T14-Av. Scanning electron microscopy of teeth of germfree rats revealed that strain T14-Vi colonized in the fissures as well as on tooth surface areas near the gingiva; strain T14-Av also colonized in fissures but was unable to colonize the teeth near the gingiva. In studies with conventional rats fed a high-sucrose diet, streptomycin-resistant strain T14-Vi colonized on the teeth of all rats inoculated with in the order of 10(8) or 10(7) CFU and on the teeth of about half of the rats inoculated with 10(6) or 10(5) CFU. In contrast, streptomycin-resistant strain T14-Av could not be detected on the teeth of any of the rats in groups similarly inoculated. In vitro "resting" cells of both strains suspended in conventional or germfree rat saliva survived to comparable degrees. [(3)H]thymidine-labeled T14-Vi cells adhered well to hydroxyapatite (HA) beads and to HA beads pretreated with saliva obtained from germfree or conventional rats. In contrast, T14-Av cells adhered less well than did T14-Vi cells to HA, whereas their adherence to saliva-coated HA was negligible. Transmission electron microscopy of negatively stained T14-Vi and T14-Av cells repeatedly passed in 1% phosphotungstic acid revealed fibrils on cells of both strains. T14-Av cells were covered by large amounts of extracellular material which was presumably heteropolysaccharide; little extracellular material was present on the surface of T14-Vi cells. T14-Vi cells had a relatively low affinity for the heteropolysaccharide synthesized by strain T14-Av. Other evidence also suggested that this polysaccharide had a relatively low affinity for saliva-coated HA. Collectively, the evidence indicates that the difference in periodontopathic potential between strains T14-Vi and T14-Av results from their different abilities to colonize teeth. This difference is probably due to the lower adherence of T14-Av cells to teeth rather than to their ability to grow in the mouth. The low affinity of T14-Av cells for tooth surfaces may be due, in part, to the presence of large amounts of cell-surface-associated polysaccharide.

Actinomyces↗