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Biomedical subjects

N Sumi

Publications and source records attributed to N Sumi.

83 records · Page 5Linked to original sources
PubMed1988

Maternal transmission and dental caries induction in Sprague-Dawley rats infected with Streptococcus mutans.

Thirty-four female rats (18 days old) were infected with Streptococcus mutans MT8148R (serotype c) or 6715 (g). Diets containing different proportions of sucrose were used to prepare the dams which harbored various levels of S. mutans in their oral cavity. Around 66 days of age, the female rats were bred and 34 dams subsequently bore 322 offspring. The dams were killed upon weaning (20 days of age) of their respective litters. There were positive correlations between the recovery of inoculated S. mutans and the caries incidence in the dams. Transmission of S. mutans from a dam to her offspring was studied in 10-, 15-, 20-, 27-, 34-, 41-, 48-, and 55-day-old rats by evaluating the recover of S. mutans from the offspring. Positive correlation between the magnitudes of recovered S. mutans MT8148R from dams and their offspring was found in all ages of young rats examined. Furthermore, caries incidence in young rats was found to be positively correlated with the recovery of both strains of S. mutans as well as with incidence of caries in their respective dams.

Animals↗
PubMed1988

Effect of inoculum size and frequency on the establishment of Streptococcus mutans in the oral cavities of experimental animals.

SPF Sprague-Dawley rats and ICR mice were inoculated with either Streptococcus mutans MT8148R (serotype c) or 6715 (g), and the influence of inoculum size, inoculum frequency, and sucrose on the establishment of S. mutans in the oral cavity was examined. Successful colonization of S. mutans in the experimental animals was absolutely dependent on the number of the cells introduced orally. Furthermore, inoculum frequency and sucrose seemed to act as secondary factors to modify the establishment of S. mutans, and it is suggested that high inoculum frequency may decrease the inoculum size necessary for the colonization of S. mutans in the oral cavity.

Animals↗
PubMed1985

Effect of mutacin administration on Streptococcus mutans-induced dental caries in rats.

A bacteriocin from serotype c Streptococcus mutans strain C3603 was examined for its inhibitory effect on experimental dental caries in rats infected with S. mutans MT8148R (serotype c). Significant reduction in the incidence of dental caries was found only when bacteriocin was incorporated both in the drinking water and in the diet at a high concentration. However, caries reduction was not as great as expected and the addition of bacteriocin to drinking water alone had no effect on the recovery of S. mutans, plaque deposition or caries incidence. The bacteriocin activity must have been reduced in the oral cavity of rats, and the reasons were examined. Bacteriocin-resistant mutants were not detected and the bacteriocin was not inactivated by saliva. Whereas the bacteriocin did not kill the S. mutans cells grown in a sucrose-containing medium, it completely killed the cells grown in a sucrose-free medium.

Animals↗
PubMed1976

The incidence of spontaneous tumors of the central nervous system of Wistar rats.

The brains of 396 old albino rats of the breed Wistar-AF/Han-EMD were examined for spontaneous tumors of the CNS and the following tumors were diagnosed: 1 oligodendroglioma, 1 astrocytoma, 1 mixed glioma, 1 pleomorphic glioma, and 19 meningiomas. Thus the CNS tumor rate was 5.8%. In addition 6 micromeningiomas were found. Knowledge of the spontaneous tumor rate including the tumor incidence in the CNS of the animal strains used for these examinations is a necessary condition for the evaluation of the results of cancerogenicity tests. CNS tumors deserve particular attention because during recent years it was found that certain chemical compounds like for instance N-methyl-N-nitrosourea induce organ-specific tumors in the brain of rats. It is recommended, therefore, to always include the central nervous system in the autopsy and histologic examination of animals from cancerogenicity trials. For cerebral autopsy transversal sections through the different cerebral regions and histologic examination of transversal section surfaces of all tumors and suspected tumor areas are suggested.

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