Apoptotic and necrotic influence of dental resin polymerization initiators in human gingival fibroblast cultures.
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The aim of this study was to examine the apoptotic and necrotic influence of four dental resin polymerization initiators--namely benzoyl peroxide (BPO), camphorquinone (CQ), dimethylaminoethyl methacrylate (DMAEMA), and dimethyl-para-toluidine (DMPT)--on human gingival fibroblast (HGF) cells. To this end, the growth inhibition of HGF cells with 1 mM BPO, CQ, and DMAEMA, and 500 microM DMPT was evaluated using Cell Counting Kit-8. Then, cell cycle analysis by flow cytometry was used to assess propidium iodide-stained cells (distribution of cells in G0/G1, S, G2/M phases). All four dental resin polymerization initiators induced G0/G1 cell cycle arrest. As for the patterns of cell death (necrosis and/or apoptosis), they were analyzed using Annexin V-FITC/PI staining with flow cytometry. All four dental resin polymerization initiators most likely induced necrosis. (+info)
Novel, multi-purpose, PMMA-type adhesive resin with newly synthesized microcapsule of radical polymerization initiators.
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The behavior of microencapsulated polymerization initiators in dental adhesives is unknown. This study investigated the effects of new microencapsulated initiators in novel, multi-purpose, PMMA-type adhesive resin on the bonding performance and polymerization reactivity. Microencapsulated BPO and 1,3,5-trimethylbarbituric acid (TMBA) with PEMA as a shell polymer were quantitatively synthesized at 97-98% yield with 30-54 microm diameter. Adhesive-MC (comprising the synthesized microcapsules) and Adhesive-BR (comprising bare BPO and bare TMBA) were prepared and stored at 5 degrees C, 23 degrees C, and 40 degrees C for two months. MMA monomer was used as a solvent for the microcapsules. At the starting period, there were no significant differences between Adhesive-MC and Adhesive-BR in shear bond strength to enamel or dentin treated with or without surface treatment agent (p<0.05); moreover, their curing times (tc=304 seconds) were almost the same. After two months' storage at 40 degrees C, Adhesive-BR degraded in bond strength and showed markedly delayed polymerization reactivity as storage period progressed. In direct contrast, it was found that Adhesive-MC still retained its capabilities for adhesion to gold alloy and initiation of radical polymerization (p<0.05). (+info)
On-line liquid chromatography and circular dichroism detection of stereo-isomers of alpha-tocopherol derivatives generated by an electrochemical reaction.
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The electrochemical oxidation of (+/-)-alpha-tocopherol on a porous graphite electrode was performed in the presence of methanol, and successive separation and detection of the products were performed by an on-line liquid chromatography/mass spectrometry system. Three products were identified, one of which was determined to be alpha-tocopheryl quinone, because its m/z was 469 [M+Na](+). The other two products showed identical mass and UV spectra, and were suspected to be diastereomers of 9-methoxy-alpha-tocopheron, because their molecular weights were m/z 483 [M+Na](+), and also because it is known that the chemical oxidation of alpha-tocopherol by benzoyl peroxide or N-bromosuccinimide in the presence of methanol should provide 9-methoxy-alpha-tocopheron. To confirm that these two compounds were diastereomers, a circular dichroism detector was used. The signs of both peaks detected by the circular dichroism detector at 230 nm were opposite. In addition to observations of identical mass and ultraviolet spectra, these results indicated that the two products were diastereomers of 9-methoxy-alpha-tocopheron, whose stereochemistry is different at the newly generated chiral center of the 9-position. The on-line use of a circular dichroism detector with an electrochemical cell/liquid chromatography system may expand the utility of the system to study the metabolism of a chiral drug. (+info)
Evidence for a common genetic pathway controlling susceptibility to mouse skin tumor promotion by diverse classes of promoting agents.
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The present study has compared different mouse stocks and strains with known sensitivity to phorbol ester skin tumor promotion for their sensitivities to skin tumor promotion by a prototypic organic peroxide (benzoyl peroxide, BzPo) and anthrone (chrysarobin, Chr) tumor promoter. Following initiation with either 7,12-dimethylbenz(a)anthracene and/or N-methyl-N'-nitro-N-nitrosoguanidine, groups of mice were promoted with several different doses of each promoting agent. Among mice selectively bred for sensitivity to phorbol ester promotion, the order of sensitivity to BzPo was inbred SENCAR (SSIn) greater than SENCAR greater than CD-1. With Chr as the promoter, the order of sensitivity was SENCAR greater than SSIn greater than CD-1. Concurrent tumor promotion experiments examined the responsiveness of two common inbred mouse strains, DBA/2 and C57BL/6. The phorbol ester-responsive mouse strain, DBA/2, was more sensitive to skin tumor promotion by Chr than was C57BL/6 at all doses tested but was clearly less sensitive than both SENCAR and SSIn mice. Finally, DBA/2 and C57BL/6 mice were similar in their responsiveness to BzPo promotion, but again both of these inbred strains were significantly less sensitive than were SSIn and SENCAR mice to this organic peroxide type of skin tumor promoter. Histological evaluations comparing SENCAR and C57BL/6 mice revealed that a major difference between these strains in response to multiple Chr and BzPo treatments was in the inflammatory response (measured by edema formation). Unlike 12-O-tetradecanoylphorbol-13-acetate, Chr and BzPo did not induce dramatic differences in the epidermal hyperplasia (as measured by epidermal thickness) in these two mouse lines. The results presented in this paper suggest that there is a common pathway controlling susceptibility to skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate, BzPo, and chrysarobin. These results are discussed in terms of a possible genetic model(s) for skin tumor promotion in mice. (+info)
Anti-acne agents attenuate FGFR2 signal transduction in acne.
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Effect of filler type and polishing on the discoloration of composite resin artificial teeth.
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In this study, the effects of filler type and polishing on the discoloration of composite resin artificial teeth were examined. Four types of experimental resins were prepared: one was a matrix resin, while the others were composite resins containing three different types of fillers (nano-sized silica filler with or without silanization, and prepolymerized filler). Specimens were immersed in distilled water, coffee, red wine, or curry. Color change after immersion was measured using a colorimeter. Color difference values (delta E) and changes in translucency parameter (delta TP) were statistically analyzed using three-way ANOVA and Tukey's comparison. On the influence of the polishing factor, statistically significant differences were neither observed in delta E nor delta TP between polished and non-polished tooth surfaces. On the contrary, the influences of filler type and discoloration medium, and their interaction thereof, were significant. With unsilanized filler, the delta E value of composite resin artificial teeth was significantly increased. (+info)
Antimicrobial property of lauric acid against Propionibacterium acnes: its therapeutic potential for inflammatory acne vulgaris.
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Adapalene 0.1% and benzoyl peroxide 2.5%: a novel combination for treatment of acne vulgaris.
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Topical products commonly used to treat acne include retinoids and antimicrobials, due to their effects on different components of pathogenesis. Accordingly, a fixed combination of adapalene 0.1% and benzoyl peroxide (BPO) 2.5% was developed (Epiduo, Galderma) and was approved by the US FDA in December 2008 for the treatment of acne. The superior efficacy of this combination was demonstrated in 2 large randomized controlled trials. This paper reviews the evidence for efficacy and tolerability of the combination of the retinoid adapalene 0.1% and BPO 2.5%, a once-daily gel formulation for the treatment of acne. (+info)