Helena Tuompo

The relationship between sugar metabolism and potassium translocation by caries-inducing streptococci and the inhibitory role of fluoride

Abstract The caries-conducive strain FA-1 of Streptococcus mutans removed more glucose than sucrose during anaerobic incubation, mainly at pH 5.8, in a medium that did not promote growth. The addition of fluoride reduced the sugar disappearance but this reduction was partly alleviated by extra potassium. The uptake of potassium by the cells was also greater in the presence of glucose than sucrose. Potassium was extruded from both fermenting and non-fermenting cells on addition of about 50 ppm fluoride. This was accompanied by a rapid uptake of fluoride by fermenting cells followed by an immediate release back into the fluid phase. Simultaneously, the concentration of intracellular sugar was higher in the presence of glucose than of sucrose. The intracellular sugar increased during the initial disappearance of the external sugar but diminished during the period of reduced sugar utilisation. Fluoride or potassium modified the intracellular sugar changes only slightly or negligibly. Acid production from the cells was greater from glucose than sucrose and both were slightly enhanced by potassium. Acid production was completely inhibited by about 50 ppm fluoride concentration. The results suggest a close association of potassium transport of this streptococcus to sugar uptake and metabolism. The inhibition by fluoride of sugar uptake and metabolism seems to be largely due to its interferring action of the cation translocation and vice versa.

Lead levels in deciduous teeth

Subclinical lead in tox ica t ion ha s r ecen t ly been recognized as a ser ious t h r e a t to h u m a n h e a l t h Ell. I n u r b a n areas, where exposure to lead is increasing, a far f rom negligible n u m b e r of chi ldren m a y be suffer ing f rom subcl inical lead poisoning wi th s i lent b ra in d a m a g e [2, 3]. Blood and ha i r levels of lead are unsa t i s f ac to ry ind ica tors of b o d y b u r d e n or of earlier exposure to lead; dec iduous tee th , however , afford a prac t ica l and sens i t ive ind ica to r of bone-seek ing e l emen t s [4], inc lud ing lead [2]. W h e n blood-lead levels of a p p a r e n t l y h e a l t h y ind iv idua l s were compa red in 14 d i f ferent countr ies , t he h i ghes t va lues were found for Hels ink i [5]. W e therefore decided to s t u d y the lead c o n t e n t of dec iduous t e e t h of ch i ldren born and l iving in Hels inki and to compare these va lues wi th those ob ta ined for chi ldren born and l iving in Tervola , a s u b u r b a n area in no r th ern F in land . The ma te r i a l ana lyzed compr i sed a to ta l of t 36 in t ac t dec iduous t e e t h ob ta ined f rom ch i ld len born be tween 1958 and 1967. E n a m e l and den t ine were s epa ra t ed by t he f lo ta t ion m e t h o d [6]. The lead complex was e x t r a c t e d in to m e t h y l i s o b u t y l k e t o n e as descr ibed [2, 7] and t he concen t ra t ion of lead was d e t e r m i n e d wi th a P e r k i n E l m e r 300 a tomicabsorp t ion spec t ropho t ome t e r . The ave rage lead c o n t e n t for all t e e th collected in Hels ink i was 69.9 468.4 p p m in ename l and 0,71 -40.82 p p m in den t i ne (mean-S .D. ) , t h e respec t ive va lues for t e e t h collected in Tervo la be ing gl .4-4-44.6 p p m and 0.46 -40.25 ppm. W h e n the va lues are p lo t ted aga ins t the b i r th year of t he t oo t h donor, t he lead c o n t e n t s of bo th ename l and den t ine show a t e n d e n c y to be e leva ted in Hels ink i (Fig. 1).

Strontium content of deciduous teeth in northern and southern Finland

A possible connection has been suggested between strontium and a low prevalence of dental caries. An investigation of this subject was initiated by measuring the strontium content of deciduous teeth by atomic absorption spectrophotometry in different regions in Finland. The material analysed consisted of a total of 2,482 tooth crowns and 392 tooth roots. The results showed that the Sr content of the tooth crowns in northern Finland was about two-fold that in the south, about 400 and 200 mug/gCa, respectively. The difference was apparently caused by corresponding differences in dietary strontium. The tooth roots contained much more Sr than the crowns, about 600 and 200 mug/gCa, respectively, in southern Finland, presumably owing to changes occurring in the dietary habits of the child during the development of the crowns and roots of the deciduous teeth.

Effect of selenium on developing mouse teeth in culture in vitro

First molars from 2-day-old mice were cultured for 7 days in medium supplemented with 0.04, 0.4, 4.0 parts/10(6) selenium (Se) or 10 per cent calf serum. Collagen synthesis, measured after labelling with [3H]-proline for the last 24 h of culture, was most active at 0.4 parts/10(6) Se. Supplementation with 300 parts/10(6) Se for the first 24 h of culture caused ultrastructural changes in newly-deposited enamel and dentine matrices.