Desulfuration of cysteine and methionine by Fusobacterium nucleatum.

Fusobacterium nucleatum is a Gram-negative anaerobic rod-shaped bacterium frequently isolated from human dental plaque. It is capable of the desulfuration of cysteine and methionine, resulting in the formation of sulfide and thiol volatiles, respectively. Intact cells, as well as cell-free extracts produced by French pressure cell lysis of F. nucleatum, hydrolyzed radiolabeled cysteine to produce sulfide, pyruvic acid, and ammonia. The hydrolysis products of radiolabeled methionine were a volatile thiol, ketobutyrate, and ammonia. Both activities were associated with the cytoplasmic component, not the membrane. The desulfuration mechanisms are heat-labile, inhibited by the presence of excess substrate, and rates are dependent upon substrate concentration. These dissimilar pathways by F. nucleatum can account in part for the presence of sulfur-containing volatile products that occur in the mouth.

Mechanism of action of an antiseptic, anti-odor mouthwash.

Inter-related determinants of oral malodor were measured over a three-hour period in 30 human subjects after mouthwash treatments. Re-odoration was important to mouthwash activity for 30 min. At post-treatment times of 60-180 min, the anti-odor activity of the product is due solely to its anti-microbial action.

Effects of an antiseptic mouthwash on odorigenic microbes in the human gingival crevice.

Odorigenic gram-negative anaerobes in human gingival crevices were significantly decreased for up to 120 minutes after rinsing with an antiseptic mouthwash. This observation parallels clinical measurements of the antiseptic effect on oral malodor and suggests that its odor-decreasing properties are related to its antimicrobial action in the mouth.

Cariostatic activity of calcium glycerophosphate in hamsters: topical vs dietary administration.

Two experiments were conducted to determine if calcium glycerophosphate administered continuously in a diet or intermittently as a single daily topical application to teeth had an anticaries potential in young hamsters that were fed a cariogenic diet. The hamsters were inoculated with a caries-conductive streptococcal strain. Within the 60-day experimental period, results of these evaluations indicated calcium glycerophosphate significantly reduces caries when fed in the diet at levels of 1% and higher, and significantly reduces caries when applied topically at levels of 2% and higher. There were no observable differences in plaque formation among treatments.

Biochemical effects of oxolinic acid on Proteus vulgaris.

Oxolinic acid (1-ethyl-1,4-dihydro-6,7-methylenedioxy-4-oxo-3-quinolinecarboxylic acid) is an antimicrobial agent effective against a variety of gram-negative pathogens, including Proteus. With the exception of Staphylococcus aureus, oxolinic acid is inactive against gram-positive bacteria and against fungi. Our results suggest that oxolinic acid exerted its primary action on synthesis of deoxyribonucleic acid (DNA). The rate of thymidine-2-(14)C incorporation into DNA was significantly depressed in the presence of 0.1 mug of oxolinic acid per ml and was markedly inhibited at 1 mug/ml. No evidence of complexing with DNA was observed. Pulse labeling with radioactive precursors revealed that at levels approximating the minimal inhibitory concentration, oxolinic acid had no effect on rate of incorporation of (14)C-valine into protein, uracil-2-(14)C into ribonucleic acid, or sodium acetate-1-(14)C into lipid. Filamentous forms of P. vulgaris ATCC 881 were observed after in vitro exposure to subinhibitory levels of oxolinic acid. Concentrations of oxolinic acid in excess of the minimal inhibitory concentration (0.39 mug/ml) did not cause lysis of cells of P. vulgaris or leakage of cytoplasmic materials. Mg(++) ions diminished the in vitro activity of oxolinic acid, possibly through formation of Mg(++) chelates