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  • 1995-1999  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 31 (1996), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We examined the site specificity of fluoride (F) distribution in human dental calculus. Teeth with supra- and subgingival calculus were obtained from patients who resided in non-fluoridated areas in Japan and China. Sequential layers of the dental calculus (30 μm thick) were abraded by an abrasive micro-sampling technique and fluoride and phosphorus in the powdered samples were analyzed. Fluoride concentrations were highest in the outer, lowest in the middle and intermediate in the inner layers of dental calculus in general. In the outermost layers fluoride concentrations were highest in calculus found near the tooth cervix both in supra- and subgingival calculus. Fluoride concentrations decreased markedly toward the apical region in subgingival calculus. while it did not change toward the incisal or occlusal region in supragingival calculus. In the inner layers, fluoride concentrations in both supra- and subgingival calculus were not affected by position on the teeth. Fluoride concentrations in subgingival calculus near the apex were lower than in supragingival calculus near the incisal or occlusal region. It was concluded that the fluoride concentrations differ in different regions of dental calculus, probably due to their different mechanisms of formation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0827
    Keywords: Fluoride ; Bone ; Defluoridation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The aim of this work was to explore the reduction of fluoride concentrations in the skeleton after stopping experimental fluoride administration. Fluoride was administered to the rats at varying doses (0, 50, 100 ppm in drinking water) and for different lengths of time (4, 13, 25 weeks). A series of fluoride concentrations across the full thickness of humerus, parietal bone, and vertebra arch in rats were measured by means of an abrasive micro-sampling technique. The distribution profiles of fluoride from periosteal to endosteal surfaces, which were apparently related to the histological structure of these bones, were U shaped in the humerus, V shaped in the parietal bone, and W shaped in the vertebra arch. The average fluoride concentrations in the bones increased significantly with each increasing dose and length of fluoride administration. The relative increments were similar between the different regions or the different bones. After stopping fluoride administration, on the other hand, the relative reduction of the average fluoride concentrations in the bones were 30–100%. They were greatly related to the length after stopping fluoride administration and the dose and length of fluoride administration, but also dependent upon the type of bone and the region examined.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-2576
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the present study was to investigate the involvement of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in PGE2 production by human gingival fibroblasts stimulated with lipopolysaccharides (LPS) from periodondopathogenic bacteria. LPS were isolated fromPorphyromonas gingivalis (P. gingivalis), Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) andEschericia coli (E. coli) by the phenol-water procedure. The three LPS preparations produced PGE2 up to 48 h in a time-dependent manner in human gingival fibroblasts.P. gingivalis-LPS was the most potent stimulator of PGE2 production and, to a lesser extent,A. actinomycetemcomitans- andE. coli-LPS. Treatment of the cells with indomethacin, a non selective COX-1/COX-2 inhibitor and NS-398, a selective COX-2 inhibitor, completely depressed PGE2 production. Treatment of dexamethasone, known to inhibit COX-2 expression, also significantly prevented PGE2 production. Immunohistochemical staining of COX-2 protein demonstrated that expression of COX-2 protein was increased at 24 h afterP. gingivalis-LPS stimulation, while expression of COX-1 protein was not affected byP. gingivalis-LPS. In order to investigate the regulation of PGE2 production,P. gingivalis-LPS-stimulated cells were treated with herbimycin A and genistein, both inhibitors of tyrosine kinases. Both the inhibitors significantly inhibited PGE2 production. Herbimycin A treatment depressed expression of COX-2 protein. These data suggest that human gingival fibroblasts stimulated with LPS from periodontopathogenic bacteria mainly produce PGE2 not by COX-1, but by COX-2, induction of which may be regulated by tyrosine kinase and that the produced PGE2 may be involved in the pathogenesis of periodontal diseases.
    Type of Medium: Electronic Resource
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