Gnotobiotic rats infected with Streptococcus mutans 6715, mutant C211 at 45 days of age and provided a purified diet containing 5% sucrose developed carious lesions on buccal, sulcal, and proximal molar surfaces within 15 days (60 days of age). The level of caries increased significantly (P 0 0.01) within the next 15 days (by day 75), and extensive decay was observed on all three molar surfaces of 90-day-old infected rats (45 days after challenge). Mutant C211 was previously shown to exhibit increased glucosyltransferase activity and greater adherence and virulence than S. mutans 6715 wild type (wt). Gnotobiotic rats (90 days of age) infected with either S. mutans AHT orS. mutans 6715 (wt) at 45 days of age developed significantly (P c 0.01) fewer caries on all molar surfaces than rats of the same age that were infected with S. mutans 6715, mutant C211. The level of plaque increased 2-fold, and the number ofviable S. mutans in plaque increased 10-fold between days 60 and 90 in rats infected with S. mutans 6715, mutant C211. Ninety-day-old rats infected with either S. mutans AHT or S. mutans 6715 (wt) had similar levels of plaque and numbers of S. mutans in plaque; however, these values were two-to fourfold lower than those observed in rats of the same age that were infected with S. mutans 6715, mutant C211.
After the administration of 2-14C folic acid to a human volunteer, urinary and fecal radioactivity, as well as urinary excretion of folate (Lactobacillus casei assay) and biopterin-like material (Crithidia fasciculata assay) were determined at intervals over a 129 day period of observation. From two 24 h urine samples erythroneopterin, bioterin, threoneopterin pterin, isoxanthopterin, and xanthopterin were isolated by chromatographic procedures, quantitated, and their specific activities were determined. The effect on the pattern of elimination of urinary radioactivity and biological activity resulting from the administration of diphenylhydantoin was studied on two occasions. Urinary radioactivity plots suggest the decay of two forms of folates with markedly different biological half lives. One short-lived (t 1/2 approximately 31.5 hr), corresponding to newly absorbed folate, and one long-lived (t 1/2 approximately 100 day) thought to represent the decay of body pools. Diphenylhydantoin does not alter the rate of elimination of the long-lived component but may accelerate losses of newly absorbed folate. The analysis of pterins does not support the hypothesis that diphenylhydantoin increases the breakdown of folates to pterins.
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