Biomedical subjects
Publications and source records attributed to J Tenovuo.
Physiological activity of lactoperoxidase and in vivo concentration of thiocyanate ions were shown to be inhibitory against a cariogenic strain of Streptococcus mutans. However, the amount of H2O2 in vivo may be too low for optimum inhibition by lactoperoxidase system. H2O2 alone also inhibited the growth of S mutants to some degree.
The antibacterial effect of purified human salivary lactoperoxidase on a cariogenic strain of Streptococcus mutans was demonstrated while another oral peroxidase, probably of leukocytic origin, did not affect the growth. Lactoperoxidase was rapidly adsorbed by bacterial cells indicating the necessity of the contact between the enzyme and the cells before inhibition.
The amino and keto acid composition of the cells of Streptococcus mutans, strain Ingbritt, maintained and grown on a Trypticase-Phytone based medium without any added carbohydrate or supplemented with xylitol or glucose, was analyzed. The results showed no remarkable differences in the portions of individual amino acids liberated by acid hydrolysis from the cellular proteins of cells grown in the above mentioned media. However, the amount of free amino acids in the water extracts of the cells grown in the glucose medium differed considerably from those obtained from cells grown in the two other media. The amounts of free amino acids of the medium at the end of the growth period were higher in the glucose containing medium than in the two other media. The content of keto acids was lower in the cells grown in the presence of xylitol or without added carbohydrate when compared to those cells grown in glucose containing medium.
An investigation was made of the effects on some biochemical characteristics of human whole saliva and dental plaque resulting from the daily consumption of three commercial, acid-containing beverages. The beverages tested were a cola beverage ("Coca-Cola"), a carbonated orange drink ("Jaffa") and single strength orange juice. Each of the three test beverages as well as non-fluoridated tap water as a control, were consumed during four two-week periods. The test group consisted of 39 dental students. The mean consumption frequency lay in the range from 5.3 to 5.7 times per day. Orange juice was found to stimulate the salivary secretion rate most. All test drinks decreased the salivary pH immediately after consumption, but the pH did not generally drotase-like activity in oral fluid. Changes were observed in calcium, phosphate and fluoride concentrations in oral fluid samples, but these were due to variations in salivary secretion rate. A significant decrease in redox potentials of whole saliva was, however, observed after consumption of the drinks. The present results indicate that in healthy persons with normal saliva flow rate and buffer capacity the moderate consumption of acidic beverages failed to induce any remarkable caries-promoting changes in oral cavity. However, in persons with low salivary flow rate erosion may be a consequence of regular consumption.
A series of rapid and simple chromatographic purification procedures for peroxidase-like enzymes occurring in the human oral cavity is presented. Samples of whole saliva, parotid saliva, gingival exudate and various bacterial preparations contain peroxidases which were purified using molecular exclusion and ion exchange chromatography, and isoelectric focusing. Salivary lactoperoxidase can be easily separated from bacterial and leucocyte peroxidase activity by the methods presented.
18 subjects (10 males, 8 females) with considerable differences in oral health conditions were examined regarding the peroxidase activity of oral fluid samples. Subjects with high caries prevalence and/or severe gingivitis displayed a significantly higher peroxidase activity than control subjects. Chromatographic experiments revealed that the increased activity was caused by salivary lactoperoxidase. This elevated activity does not, however, necessarily lead to better oral health because the antibacterial activity of lactoperoxidase also depends on the concentrations of thiocyanate ions and hydrogen peroxide. Hence the specific activity of lactoperoxidase, determined in vitro, is not as such as adequate measure of its antibacterial efficacy.
18 subjects, 9 males and 9 females, were examined regarding salivary oxidation-reduction potential, salivary flow rate, salivary peroxidase activity, oxidation-reduction potential of dental plaque samples, and dental health. Both the peroxidase activity, expressed as the salivary lactoperoxidase, and the salivary oxidation-reduction potential increased with increasing salivary flow rate. The variation of these variables was obviously due to changes in salivary flow rate during the day. The remarkably slight differences in peroxidase activities, oxidation-reduction potentials and salivary flow rate in this study did not have any marked correlation with the clinical recordings of the test groups.
Detailed biochemical analyses of peroxidases in saliva, plaque and gingival exudate samples were carried out in view of the preliminary findings that the peroxidase activity of centrifuged oral fluid was considerably higher in the xylitol group than in the fructose or Sucrose groups. Chromatographic experiments revealed the activity which was increased due to the intake of xylitol, to be attributed to the involvement of the salivary lactoperoxidase, and not to enzymes formed in plaque or leucocytes. There were no significant differences between the sugar groups in the concentration of thiocyanate ions (mean 92 mg/l) and ionized iodine (mean 1.6 mug/l), but the concentration of ionized fluorine in saliva was lower in the xylitol group (0.128 mg/l) than in the other groups (0.150 mg/l). There were no clear differences in the salivary redox potential between the sugar groups. It is evident that various sugars selectively affect the enzyme and other production of the salivary glands. Xylitol-induced elevation of the salivary lactoperoxidase activity and the cariostatic properties of xylitol may partly be interrelated phenomena due to the antibacterial properties of lactoperoxidase.
We studied differences in the amounts of organic and inorganic mercury in saliva samples between amalgam and nonamalgam human study groups. The amount of organic and inorganic mercury in whole saliva was measured in 187 adult study subjects. The mercury contents were determined by cold-vapor atomic absorption spectrometry. The amount of organic and inorganic mercury in paraffin-stimulated saliva was significantly higher (p<0.001) in subjects with dental amalgam fillings (n = 88) compared to the nonamalgam study groups (n = 43 and n = 56): log(e) (organic mercury) was linearly related to log(e) (inorganic mercury, r(2) = 0.52). Spearman correlation coefficients of inorganic and organic mercury concentrations with the number of amalgam-filled tooth surfaces were 0.46 and 0.27, respectively. Our results are compatible with the hypothesis that amalgam fillings may be a continuous source of organic mercury, which is more toxic than inorganic mercury, and almost completely absorbed by the human intestine.
Xylitol is effective as a noncariogenic or even cariostatic sugar substitute. Habitual xylitol consumption appears to select for mutans streptococci (MS) which shed easily into saliva from plaque. We have earlier shown that habitual xylitol consumption of mothers was associated with a statistically significant reduction in the probability of mother-child transmission of MS assessed at 2 years of age. The aim of the present study was to assess the children's MS counts 1 and 4 years after the maternal xylitol consumption had been discontinued. At baseline, during pregnancy, all mothers (n = 195) showed high salivary levels of MS. The mothers were randomly assigned to xylitol, fluoride (F) and chlorhexidine (CHX) groups. In the xylitol group, the mothers chewed xylitol-sweetened gum, for 21 months, starting 3 months after delivery. In the two control groups, the mothers received CHX or F varnish treatments at 6, 12 and 18 months after delivery. At the 2-year examination, 169 mother-child pairs participated. At the 3-year and 6-year examinations, there were 159 and 147 children in the study, respectively. For children's MS analyses, visible plaque was collected using toothpicks at the age of 3 and paraffin-stimulated saliva at the age of 6. The persons involved in the collection and analysis of the microbiological samples were blinded as to the study design and group. Both the plaque and salivary MS were cultured on Mitis salivarius agars containing bacitracin. In all groups, the colonization percentages increased during the follow-up. At the 3-year examination, the children's risk of having MS colonization was 2.3-fold in the F group (95% CI 1.3-4.2) compared to the xylitol group. This difference was statistically significant. Even at 6 years of age, the salivary MS levels were significantly lower in the xylitol group than in the other groups (ANOVA, p<0.001). In conclusion, the earlier demonstrated, xylitol-associated reduction in the probability of mother-child transmission of MS was still found in the children's MS counts at the age of 3 and 6 years.
This study examines the possible effect of the antimicrobial peroxidase system on the activity of streptococcal glucosyltransferases B, C and D (GtfB, GtfC and GtfD), either in solution (GtfB and GtfC) or when adsorbed to hydroxyapatite (GtfC and GtfD) at pH 6.5. The lactoperoxidase (LP) system (LP, H(2)O(2), SCN(-)) had no effect on the activity of dissolved GtfC, but the activity of dissolved GtfB was enhanced. The LP system, however, strongly inhibited the activities of both GtfC and GtfD in their adsorbed form. LP enzyme, without its substrates, inhibited all three Gtf enzymes: GtfB and GtfC in concentrations between 10 and 100 microg/ml in liquid phase and adsorbed GtfC and GtfD in concentrations between 25 and 50 microg/ml. This inhibition was in part abolished in liquid phase, but not in solid phase, if the substrates of LP were added. This study shows that the lactoperoxidase system can exert inhibitory activity against streptococcal Gtfs without generating oxidizing agents.
Whole saliva samples of volunteers who ate a strict diet for two years with regard to the type of sweeteners used (sucrose, fructose, and xylitol) showed considerable differences in the lactoperoxidase activity. The consumption of a xylitol diet increased the activity of this enzyme fourfold to tenfold when compared to the other two test groups. Lactoperoxidase belongs to the natural defense mechanisms of the oral cavity. However, the consumption of a xylitol diet also leads to a strong reduction in the incidence of dental caries. It is suggested that the xylitol-induced elevation of the salivary lactoperoxidase activity and the cariostatic properties of xylitol are partly interrelated phenomena.
The concentration of thiocyanate and ionizable iodine was determined with saliva samples from two test groups, smokers (N = 27) and nonsmokers (N = 92). The contents of both ions were also compared as to sex and the amount of cigarettes smoked. The concentrations of the ions studied were dependent on each other-the less iodine, the more thiocyanate in the samples. Females had significantly more iodine and less thiocyanate concentrations than males. Smoking had an increasing effect on the concentration of thiocyanate and a decreasing effect on the content of ionizable iodine in the saliva of the volunteers. The lower amount of iodine ions in the saliva of smokers may restrict the nonthyroidal metabolism of the thyroid hormone in humans.
Whole saliva from 53 children who had been tonsillectomized when they were younger than 4 years old was analyzed for selected antimicrobial proteins and oral mutans streptococci 3-4 years after the operation. The results were compared with those from age- and gender-matched control children with no history of tonsillectomy. The salivary analyses comprised both immune (total IgA, IgG and IgM) and selected nonimmune (lactoferrin, myeloperoxidase, salivary peroxidase) antimicrobial proteins. Specific IgA and IgG antibodies against viral antigens (adeno-, cytomegalo-, respiratory syncytial- and Epstein-Barr-viruses) and against Streptococcus mutans cells were quantitated in both groups. The tonsillectomized children had statistically significantly higher concentrations of all immunoglobulin isotypes (P 0.001) as well as of lactoferrin (P less than 0.005), and myeloperoxidase (P less than 0.001) in saliva. However, no differences were found in the numbers of cariogenic mutans streptococci or in the total oral aerobic flora. In line with the streptococcal counts, no differences existed in anti-S. mutans IgA or IgG titers between the groups. Most antibodies against viruses, especially of IgG isotype, were significantly (P less than 0.001) higher in saliva of tonsillectomized children than in that of the controls. The results suggest that, within a long run, the humoral immune status of human saliva is not weakened by tonsillectomy. Also, mainly serum-derived antimicrobial proteins (myeloperoxidase, lactoferrin, IgG) exist in high concentrations in whole saliva after tonsillectomy.
We selected 327 7-month-old infants and divided them into two groups based on the frequency of salivary close contacts between mother and infant. Five to seven years later, all first-born children (N = 55) whose dental development had been followed regularly, were examined for dental caries and prevalence of salivary mutans streptococci (MS) and lactobacilli. The children with frequent maternal close contacts (F group, N = 21) had significantly less MS in saliva than the children with rare close contacts (R group, N = 34, P = 0.02). Only 19% of the children in F group compared with 56% in R group had experienced caries in their primary molars and/or canines (P < 0.01). A significantly greater proportion of the children in F group (57%) than in R group (27%, P < 0.05) had a high intake of sugar-containing foods and drinks in a 2-day dietary history. The F and R groups did not differ significantly with respect to other children's caries risk factors, or in age, sex, stage of dental development, dental treatment, or the social aspects studied. There were no significant differences between F and R groups in maternal caries experience, salivary MS or lactobacillus counts, or in maternal background factors (age, breast feeding, or education). Frequent transfer of maternal saliva to the mouth of the baby before tooth eruption was negatively associated with oral infection by MS and to caries in the primary dentition, possibly due to protective immune mechanisms.