Glutathione metabolism in red cell aging.

Normal human red cells were centrifugally separated according to age by discontinuous density gradient of Percoll. Reduced glutathione (GSH), GSH stability and glucose-6-phosphate dehydrogenase (G6PD) activity in fractionated red cells decreased with age, while oxidized glutathione (GSSG) and methemoglobin (MetHb) increased with age.

Changes in some biological properties of Streptococcus salivarius isolates from infected rats.

Isolation of colonies with altered colonial morphology was frequently observed following infection of specific pathogen-free rats fed a caries-inducing high sucrose diet with two human strains of Streptococcus salivarius. These isolates produced unique rough colonies on mitis salivarius agar, in contrast to the smooth, mucoid colonial morphology of the parental strain. The rough variants were characterized by a marked increase in the synthesis of polysaccharide from sucrose, especially cell-associated water-insoluble glucan, whereas the smooth parental strains mainly produced cell-free fructan. Glucose-grown cells of rough variants but not smooth parental strains were aggregated upon addition of sucrose. Such variants were not detected during laboratory transfers of the human strains of S. salivarius nor by mutagenesis of the cultures.

Isolation and mode of action of a cell-free bacteriocin (mutacin) from serotype g Streptococcus mutans MT3791.

A bacteriocin, mutacin MT3791, was isolated from the culture supernatant of a dialysate medium of Tryptose phosphate broth cultures of Streptococcus mutans MT3791 (serotype g), a clinical isolate from a carious lesion of a Japanese child. The mutacin was found to inhibit the growth of most indicator strains of S. mutans and S. salivarius by the drop assay method. The mutacin was purified 1,450 fold from culture supernatant of S. mutans MT3791 by 60% saturated ammonium sulfate precipitation, followed by ultracentrifugation at 300,000 X g for 18 h. Gel filtration studies using Sepharose 4B indicated that the mutacin was highly aggregated, but could be dissociated by addition of 1% (final concentration) Tween 80 or 6M urea. The mutacin was heat stable, but the activity was destroyed after autoclaving at 120 degrees C for 60 min. It was susceptible to the enzymatic action of papain and pronase, but not trypsin, lipase or nucleases. The mutacin was adsorbed to whole cells of most strains of S. mutans. Mutacin MT3791 was bactericidal for an indicator strain, S. mutans MT703R (serotype e). The mutacin inhibited the incorporation of isotope-labelled precursors of protein, DNA, and RNA. Furthermore, mutacin MT3791 selectively and markedly suppressed the growth of S. mutans present in the dental plaque obtained from active carious lesions in the teeth of children. Possible role of mutacin in vivo was discussed with special reference to oral microbial ecology.

Dental caries induction in experimental animals by clinical strains of Streptococcus mutans isolated from Japanese children.

Oral implantation and the cariogenic activity of clinical strains of Streptococcus mutans which had been isolated from Japanese children and labeled with streptomycin-resistance were examined in specific pathogen-free Sprague-Dawley rats. All the seven strains tested were easily implanted and persisted during the experimental period. Extensive carious lesions were produced in rats inoculated with clinical strains of S. mutans belonging to serotypes c, d, e, and f, and maintained on caries-inducing diet no. 2000. Noninfected rats did not develop dental caries when fed diet no. 2000. Type d S. mutans preferentially induced smooth surface caries in the rats. Strains of other serotypes primarily developed caries of pit and fissure origin. Caries also developed in rats inoculated with reference S. mutans strains BHTR and FAIR (type b) that had been maintained in the laboratories for many years. However, the cariogenicity of the laboratory strains was found to have decreased markedly. All three S. sanguis strains could be implanted, but only one strain induced definite fissure caries. Two S. salivarius strains could not be implanted well in the rats and therefore they were not cariogenic. Four different species of lactobacilli also failed to induce dental caries in rats subjected to similar caries test regimen on diet no. 200. S. mutans strain MT6R (type c) also induce caries in golden hamsters and ICR mice, but of variable degrees.

Dental findings of the elderly with or without senile dementia at a special nursing home.

Survey of dental health condition was performed at a special nursing home for the elderly with senile dementia (28 subjects, 83.3 +/- 6.8 year-old; SD group) or without senile dementia (68 subjects, 84.6 +/- 7.2 year-old; NSD group). There was no difference in number of teeth survived between SD and NSD groups. However, the elderly in SD group had more unfunctionable and/or unrestorable teeth (C4) and less sound and filled teeth (SFT) than those in NSD group. Number of teeth of the elderly in 85- to 89-year-old group was smaller than those of not only younger but older age groups, irrespective of senile dementia. Lower canines showed the highest survival rate among all kinds of teeth in SD as well as in NSD group.