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L Stösser

Publications and source records attributed to L Stösser.

42 records · Page 3Linked to original sources
PubMedDate not supplied

Differences in acidogenicity of S. sobrinus and S. rattus are linked to the catalytic efficiency of the glycolytic key enzyme phosphofructokinase.

This contribution describes the biochemical properties of two catalytically different phosphofructokinases (PFKs) purified from Streptococcus rattus LB 2 (PFK-rat) and Streptococcus sobrinus OMZ 65 (PFK-sob), respectively. Steady-state kinetics revealed K(M) = 0. 8 mM for PFK-rat and K(M) = 0.08 mM for PFK-sob for F-6-P as the substrate. The enzymes also differ in their pH profiles: whereas the highest activity of PFK-rat was measured at pH = 8.0, the optimum pH of PFK-sob was at pH = 7.0. In addition, compared to PFK-sob, PFK-rat was more sensitive against the allosteric inhibitor ATP. PFK catalyzes a committed step of glycolysis, the main acid producing catabolic pathway. Thus, the catalytically more efficient enzyme isolated from S. sobrinus OMZ 65, especially at low pH, could explain the comparably high acidogenicity of this strain.

Bacterial Proteins↗
PubMedDate not supplied

Peroxidase reaction as a parameter for discrimination of Streptococcus mutans and Streptococcus sobrinus.

425 strains of mutans streptococci and 12 reference strains were investigated by membrane fatty acid spectra (MFAS) and peroxidase reaction (PR) after aerobic and anaerobic incubation. 423 strains were identified as Streptococcus mutans. The remaining 2 strains were identified as Streptococcus sobrinus. The PR of 29 strains was doubtful; immediately after anaerobic incubation a negative PR changed into a slightly positive PR. To test the diagnostic value of PR the strains were additionally investigated by means of species-specific polymerase chain reactions (PCR). The species-specific PCRs were developed on the basis of the respective genes of 16S rRNA of the pathogens S. mutans and S. sobrinus. Specificity and sensitivity were tested on reference strains (n = 17) and negative control strains (n = 39). The results of this investigation showed that an anaerobic incubation regime could lead to false-positive (S. mutans) or false-negative (S. sobrinus) PR. The 425 MS strains were classified as either S. mutans (n = 420) or S. sobrinus (n = 5). The findings on the reference strains required a reclassification of S. mutans V 100 into S. sobrinus V 100. Summarising, it is possible now to differentiate strains of mutans streptococci by MFAS and PR after aerobic incubation.

Aerobiosis↗
PubMedDate not supplied

Comparison of different DIAGNOdent cut-off limits for in vivo detection of occlusal caries.

This study tested recently recommended cut-off limits for the laser fluorescence based device DIAGNOdent (KaVo) for detection of occlusal caries. Two hundred and forty-eight permanent molars from 94 patients (mean age 19.2 years) of a general dental practice were included. After professional tooth cleaning, the teeth were examined visually and by the laser fluorescence method. The extent of occlusal lesions (gold standard) was determined after minimal operative intervention. Upon fissure opening, 24 teeth had enamel caries and 224 teeth revealed dentin caries, of which 58 and 166, respectively, were up to or beyond half the dentin. The optimal cut-off limits based on the highest kappa-values (0.51 and 0.54) were > 18 for superficial dentinal caries (D3) and > 37 for deep dentinal caries (D4). The comparison with DIAGNOdent cut-offs given by the manufacturer (n = 4) and those based on clinical trials with in vivo validation (n = 4) and in vitro studies with histological validation (n = 3) revealed a considerable variation in performance. Recommended cut-offs between 17 and 21 for superficial dentin lesions were in the same order of magnitude (0.48-0.51). On the D4 level, only the manufacturer's cut-off of > 34 achieved the best performance (0.51). According to the highest kappa-values and the area under the ROC curves (D3: A(z) = 0.903; D4: A(z) = 0.830), the agreement between the extent of validated caries and laser fluorescence value is still unsatisfactory.

Adult↗