PubMed · 13687440
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E C BARTLETT. 1961. A simplified method or recording agar diffusion plates.. https://pubmed.ncbi.nlm.nih.gov/13687440/
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Mutans streptococci are oral bacteria with a key role in the initiation of dental caries, because their glucosyltransferases synthesize polysaccharides from sucrose that allow them to colonize the tooth surface. Among the strategies to prevent dental caries that are being investigated are (1) the inhibition of bacterial growth of mutans streptococci or (2) the inhibition of glucosyltransferases involved in polysaccharide formation. Pure fatty acid esters of sucrose, maltose and maltotriose were synthesized by an enzyme-catalyzed process and tested as inhibitors of two glucosyltransferases of great homology, those from Streptococcus sobrinus and Leuconostoc mesenteroides NRRL B-512F. In spite of having their nonreducing end glucose blocked at 6-OH, they did not inhibit dextran synthesis. However, their effect on the growth of S. sobrinus in the solid and liquid phase was notable. 6-O-Lauroylsucrose, 6'-O-lauroylmaltose and 6"-O-lauroylmaltotriose at 100 microg/mL showed complete inhibition of S. sobrinus in agar plates. Consequently, these nontoxic derivatives are very promising for inclusion in oral-hygiene products aimed at disrupting plaque formation and preventing caries.
Osteoporosis is associated with the pathogenesis of urinary stone formation. Urinary stones are similar to bone diseases such as osteoporosis and bone metabolism in terms of pathogenesis. Bisphosphonates are potent inhibitors of bone resorption, and are used in the management of bone disease. Furthermore, bisphosphonates have a strong affinity for calcium, and a reported inhibitory effect on calcium oxalate crystallization in vitro. Thus, bisphosphonates might also inhibit urinary stone formation. Madin-Darby canine kidney (MDCK) cells form calcium phosphate microliths at the basolateral side in vitro. We investigated the inhibitory effects of new generation bisphosphonates (alendronate and incadronate) on calcium phosphate microlith formation and on the expression of osteopontin, which is an important urinary stone matrix. MDCK cells formed two types of colonies in three-dimensional soft agar culture; dark colonies containing calcium phosphate microliths and clear colonies free from microliths. We applied purified alendronate and incadronate at concentrations of 10(-11), 10(-9), 10(-7) and 10(-5) M to MDCK cells cultured in three-dimensional soft agar and investigated the efficiency of colony formation and the dark colony ratio (number of dark colonies relative to the total number of colonies). The administration of 10(-9) and 10(-7) M alendronate decreased the dark colony ratio compared with controls, whereas incadronate did not significantly alter this colony ratio compared with controls. The expression of osteopontin in cultured cells was inhibited by the 10(-7) M alendronate administration. The present findings show that alendronate inhibits calcium stone formation, suggesting that it is effective in the prevention of urolithiasis.
Hepatocellular carcinoma (HCC) is one of the most common malignancies in Southeast Asia. Although inactivation of pRb2/p130 has been reported in a variety of human cancers, its function in HCC has not been established. In this study we report that loss of expression of pRb2/p130 was detected by immunohistochemistry and western blotting in 15.2% (7 of 46) HCCs examined. High levels of pRb2/p130 expression were found in 84.8% (39 of 46) HCCs studied. Western blot analysis revealed that HCC had 3.5-fold higher pRb2/p130 than adjacent benign liver (ABL) tissues. 71.7% (33 of 46) of HCCs examined exhibited both nuclear and cytoplasmic staining for pRb2/p130. Cytoplasmic staining was found in 93.5% (43 of 46) of ABL tissues. Overproduction of pRb2/p130 in HepG2 cells led to growth suppression, cell cycle arrest in G0/G1, altered cell morphology, inhibition of in vitro colony formation and reduction in tumourigenicity in SCID mice. This demonstration suggests a role of pRb2/p130 as a tumour suppressor protein in HCC and the loss of this protein may lead to the development or progression of HCC. Overexpression of pRb2/p130 in HCC was, therefore, suggested to be a programmed protective response of the organism to uncontrolled proliferation.