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M L Sund

Publications and source records attributed to M L Sund.

25 records · Page 2Linked to original sources
PubMed1980

Regulation of synthesis of beta-fructofuranosidase (invertase) in Streptococcus mitis.

beta-Fructofuranosidase activity was found to be cell-bound in Streptococcus mitis ATCC 903. The following evidence suggests that induction functions as a regulatory mechanism for beta-fructofuranosidase in S. mitis: (1) on transfer of glucose-grown exponential phase bacteria to sucrose medium, the specific activity of beta-fructofuranosidase increased fourfold in the course of one generation; (2) other sugars had no stimulatory effect on the rate of synthesis of beta-fructofuranosidase; (3) the effect of sucrose on the rate of synthesis of beta-fructofuranosidase could be measured within a few minutes. Glucose, fructose and mannose repressed beta-fructofuranosidase. The addition of glucose to bacteria growing on sucrose repressed beta-fructofuranosidase for about one generation. The intracellular concentration of glucose was considerably increased during repression, while the intracellular concentration of glycolytic intermediates did not vary significantly.

Carbohydrate Metabolism↗
PubMed1978

Isoelectric focusing studies on the beta-fructofuranosidases and alpha-glucosidases of Streptococcus mitis.

Extracts of Streptococcus mitis ATCC 903 were analysed for beta-fructofuranosidase and alpha-glucosidase activities by isoelectric focusing in thin-layer polyacrylamide gels combined with zymogram procedures. Three bands of activity were visualized in the gels after incubation with sucrose (pI 4.05, 4.25 and 4.85) and three other bands after incubation with p-nitrophenyl alpha-D-glucopyranoside (pI 3.90, 4.45 and 4.65). The enzymes responsible for the reaction with sucrose were identified as beta-fructofuranosidases (EC 3.2.1.26) for the following reasons: identical enzyme bands were visualized in the gels after incubation with raffinose; no enzyme bands appeared in the gel after incubation with the alpha-glucosides maltose, turanose, trehalose and melezitose; and the soluble fraction hydrolysed sucrose to equimolar amounts of glucose and fructose.

Glucosidases↗
PubMed1976

Autolysis in strains of viridans streptococci.

Seven strains of viridans streptococci of the species Streptococcus sanguis, S. mutans and S. mitis were investigated for autolysis. The effect of pH, salt concentration and temperature on the autolytic process was studied in Na2HPO4/NaH2PO4 buffer. Whole cells and walls of all strains autolysed most rapidly at pH values above 7. Autolysis of whole cells of S. sanguis and one strain of S. mitis (ATCC15909) was maximal in 0-05 TO 0-2 M buffer, while the two S. mutans strains and S. mitis ATCC15912 showed maximal autolysis in 0-5 and 1-0 M buffers. Cultures harvested in the stationary phase of growth possessed only slightly decreased autolytic activity compared with those from the exponential phase. Whole cells autolysed more rapidly at 37 degrees C Than at 45 degrees C and 10 degrees C. Autolysis of isolated walls of three strains of S. mitis (ATCC903, ATCC15909 and ATCC15912) was maximal at pH 7-0 AND 7-5 and in 1-0 M buffers. Streptococcus mitis ATCC15909 also showed maximal lysis in 0-01 M and 0-5 M buffers. An endopeptidase action of the autolytic system of S. mitis ATCC15912 was indicated by the progressive release of soluble amino groups during autolysis of the walls. No release of reducing groups was observed. Several free amino acids were released during autolysis of these walls, alanine, lysine and glutamic acid being in greatest quanitity.

Amino Acids↗
PubMedDate not supplied

Effect of chlorhexidine gel treatment on the prevalence of mutans streptococci and lactobacilli in patients with impaired salivary secretion rate.

The potential pathogenic role of mutans streptococci in the etiology of dental caries is well-documented. Mutans streptococci are sensitive to chlorhexidine (CHX), and several methods for the clinical use of CHX have been described. An important target group for caries-preventive measures is patients with impaired salivary secretion due to the use of therapeutic drugs such as psychotropics. The aim of the present study was to compare two methods for antimicrobial treatment in such patients. Twenty-four volunteering patients at a hospital clinic were randomly divided into three groups: Group A, in which each participant was treated with 10% CHX gel in gel trays on two consecutive days, followed by application of a fluoride varnish; Group B, in which the patients were treated with the same CHX gel as above; and Group C, which was used as a control. After treatment, there was a reduction of mutans streptococci in the two groups treated with CHX. In group A, the sames collected one, three, and five weeks after the treatment were significantly lower than baseline values. No clearcut reduction of the number of mutans streptococci was observed in the subjects not treated with CHX. These data indicate that treatment with CHX gel in gel trays is superior to polishing the teeth with CHX gel. From a clinical point of view, our observations suggest that it is important to monitor the effect of antimicrobial treatment individually in order to optimize preventive programs in patients with impaired salivary secretion.

Adult↗