Effect of ozonated water on the surface roughness of dental stone casts.

Infection control of dental stone cast is an important issue. Ozone is effective for disinfection against microorganisms and inactivation of viruses. However, there is little information regarding the use of ozone. We prepared 4 types of gypsum specimens and 3 types of disinfectants (4-5 ppm Ozonated water [OZW], 2% glutaraldehyde [GL], and 1% sodium hypochlorite [SH]). Gypsum specimens were immersed in each disinfectant for 5 and 10 min, and surface roughness was then examined using laser scanning microscopy. Surface microstructure was investigated using scanning electron microscopy. Immersion of gypsum specimens in SH, GL, and OZW increased the surface roughness to a maximum of 1.04, 0.37, and 0.30 µm, respectively, based on the difference between the average values of surface roughness before and after the disinfection procedure. The effects of OZW and GL were comparable. OZW is useful as a candidate for relatively safe disinfection of material for dental stone casts.

The extracts of Japanese willow tree species are effective forapoptotic desperation or differentiation of acute myeloid leukemia cells.

BACKGROUND: The antileukemic activity of hot water extract of plant parts of some Japanese willow tree species grown at different levels of nitrogen were examined. MATERIALS AND METHODS: Water extracts of willow leaves were prepared for this studies in different level of nitrogen nutrition. RESULTS: The extracts obtained from the leaves and stem exhibited anti-leukemic activities prominently. The crude hot water extracts of the young growing parts including apex, matured leaves and stem, killed the blasts of acute myeloid leukemia (AML) cells, (HL60 and NB4) after 48h incubation, however, such desperation was far less in the root extract. Similar to the plant parts, response of extracts obtained from different willow species was not identical; the proportion of dead cells relative to whole cells of the culture medium ranged from 21% to 93% among the species. Leaf extracts obtained from the responsive willow species decreased the live cell percentage and increased the dead cell percentage at higher level of nitrogen nutrition. The mode of desperation of leaf extract treated AML cells in such species appeared to be cell apoptosis as shown by binding with fluorescein isothiocyanate (FITC) -labeled Annexin V. CONCLUSION: Differentiation of alive AML cells continued unabated and apoptosis was poor when extract of an unresponsive species added to the culture medium.

Irradiation effect on osteoclastogenesis stimulated by breast cancer cells.

To examine the effects of carbon ion and gamma ray irradiation on cancer-induced osteoclastogenesis, mouse calvaria MC3T3-E1 cells were cultured with conditioned medium from irradiated and non-irradiated MCF7 human breast cancer cells. The authors examined RANKL and OPG mRNA expression in osteoblastic MC3T3-E1 cells following treatment with conditioned MCF7 medium. Co-cultured MC3T3-E1 and bone marrow cells treated with conditioned medium from irradiated MCF7 cells showed decreased numbers of osteoclasts, assessed using TRAP staining. Conditioned medium from control MCF7 cells elevated the RANKL/OPG mRNA ratio in MC3T3-E1 cells; this effect was suppressed by carbon ion irradiation of the MCF7 cells. These data demonstrate that indirect interactions between breast cancer cells and MC3T3-E1 cells induce osteoclastogenesis in vitro through modulation of RANKL expression and that this process is suppressed by carbon ion irradiation.

Effects of high-dose major components in oral disinfectants on the cell cycle and apoptosis in primary human gingival fibroblasts in vitro.

We evaluated the effects of high-dose major components in oral disinfectants on oral cells from the standpoints of the cell cycle and apoptosis. We examined the viability and cell cycle of human gingival fibroblasts (HGFs) treated with the components of dental disinfectants, benzethonium chloride (BEC), benzalkonium chloride (BAC), and povidone iodine (PVD-I) using a cell counting kit and flow cytometry. The IC(50) inhibitory concentration value in HGF cultures at 24 hours was 1.3x10(-2) mM BEC, 6.0x10(-3) mM BAC, and 2.6x10(-1) mM PVD-I. In the cell cycle analysis, propidium iodide-stained HGFs were arrested in G(0)/G(1) of the cell cycle by all three disinfectants, and in the apoptosis assay, annexin V-FITC/PI-stained HGFs that became apoptotic at 5.0x10(-2) and 1.0x10(-1) mM BEC and 5.0x10(-2) and 1.0x10(-1) mM BAC, but not in PVD-I at concentrations as high as 5.0x10(-1) mM. Our findings describe the effects of high-dose oral disinfectants, rather than clinical concentrations. Nevertheless, appreciating the effects of high-dose disinfectants absorbed into the human body is important, where they may accumulate in specific tissues and cells.

Influence of chlorine dioxide on cell death and cell cycle of human gingival fibroblasts.

OBJECTIVES: The effects of chlorine dioxide (ClO2), sodium hypochlorite (NaOCl), and hydrogen peroxide (H2O2) on cell death and the cell cycle of human gingival fibroblast (HGF) cells were examined. METHODS: The inhibition of HGF cell growth was evaluated using a Cell Counting Kit-8. The cell cycle was assessed with propidium iodide-stained cells (distribution of cells in G0/G1, S, and G2/M phases) using flow cytometry. The patterns of cell death (necrosis and apoptosis) were analyzed using flow cytometry with annexin V-FITC/PI staining. RESULTS: The lethal doses for 50% of the cells (LD50) of ClO2, NaOCl, and H2O2 were 0.16, 0.79, and 0.11 mM, respectively. All three dental disinfectants induced G0/G1 cell cycle arrest. H2O2 induced apoptosis at concentrations of 0.05 and 0.1 mM, while NaOCl and ClO2 did not induce significant apoptosis at any concentration examined. CONCLUSIONS: These results suggest that ClO2 is sufficient for use as a dental disinfectant compared with H2O2 or NaOCl.

High-risk human papillomavirus type 16 E7 oncogene associates with Cdc25A over-expression in oral squamous cell carcinoma.

Cells expressing high-risk human papillomavirus (HPV) E7 protein display impaired checkpoint control after DNA damage and exhibit elevated rates of mutagenesis. Repression of HPV E7 expression results in the subsequent accumulation of hypophosphorylated retinoblastoma protein and repression of the Cdc25A genes. No study has been conducted to elucidate the role of Cdc25A in the development and progression of human oral carcinomas. To confirm Cdc25A protein expression together with HPV, immunohistochemistry, Western blotting, polymerase chain reaction (PCR), and reverse transcriptase (RT)-PCR were performed using various histological subtypes of oral carcinomas. Cdc25A protein was localized predominantly in the cell nuclei in carcinomas, and high expression was found in 54% of primary tumors. HPV-16 E7 was not found in non-neoplastic oral tissues, whereas it was observed in eight (36%) of 22 oral carcinomas. We found a significant correlation between Cdc25A over-expression and HPV-16 E7 positive carcinomas. There was a strong positive correlation between Cdc25A over-expression and tumor size and TNM stage. This study suggests that Cdc25A is likely to be an important mediator in the progression of oral tumors, and HPV-16 E7 may be a sensitive indicator of the involvement of viral oncogenes in oral carcinogenesis.

Apoptotic and necrotic influence of dental resin polymerization initiators in human gingival fibroblast cultures.

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.

Estrogenic activity of phthalate esters by in vitro VTG assay using primary-cultured Xenopus hepatocytes.

Estrogenic activity of phthalate esters in dental soft resins was evaluated with an amphibian system consisting of a vitellogenin (VTG)-detecting Enzyme-Linked Immunosorbent Assay and a primary-cultured hepatocyte assay using adult male Xenopus laevis. In particular, phthalate esters--Di-n-butyl phthalate (DBP), Butyl phthalyl butyl glycolate (BPBG), Benzyl butyl phthalate (BBP), and Benzyl benzoate (BB)--were investigated. Bisphenol A (BPA) was prepared for comparison with these chemicals, and 17beta-estradiol (E2) was used as a positive control. The chemicals were diluted in dimethyl sulfoxide (DMSO) to obtain final concentrations ranging from 10(-11) to 10(-4) mol/l. BPA induced estrogenic activity at a concentration of 1.1x10(-6) mol/l, while E2 showed at 4.1x10(-11) mol/l. DBP, BBP, BB, and BPBG showed no estrogenic activity at concentrations between 4x10(-7) mol/l and 1x10(-4) mol/l. The latter result indicated that these phthalate esters might be metabolically transformed into non-estrogenic substances in Xenopus hepatocytes. Furthermore, this study demonstrated that through in vitro metabolism assessment, the estrogenic activity of chemical substances could be directly detected in terms of VTG secretion in primary-cultured Xenopus hepatocytes.

Different effects of carbon ion and gamma-irradiation on expression of receptor activator of NF-kB ligand in MC3T3-E1 osteoblast cells.

We investigated the effects of carbon ion and gamma-irradiation on osteoblastic MC3T3-E1 cells by comparing mRNA expression levels for RANKL and osteoprotegerin by RT-PCR. MC3T3-E1 cells were irradiated with 2, 4, or 6 Gy of carbon ions or gamma-rays, and total RNA was harvested 1, 2, 3, 5, or 7 days after irradiation. The RANKL mRNA/OPG mRNA ratio in carbon ion-irradiated MC3T3-E1 cells was lower, while in gamma-irradiated MC3T3-E1 cells this ratio was higher than in non-irradiated cells. To evaluate osteoclastogenesis of MC3T3-E1 cells, carbon ion- or gamma-irradiated cells were co-cultured with non-irradiated cells from murine bone marrow. Staining for tartrate-resistant acid phosphatase (TRAP) in co-cultures showed that carbon ion irradiation suppressed osteoclastogenesis. This result is consistent with the lower RANKL/OPG mRNA ratio for carbon ion-irradiated cells. These results suggest that carbon ion irradiation acts primarily on osteoblastic cells, leading to a decrease in the RANKL/OPG mRNA ratio. This effect, in turn, leads to a decrease in osteoclastogenesis and osteoclast activity, which results in an increase in bone volume.

Changes in osteoclasts after irradiation with carbon ion particles.

We examined the effects of radiation on decreases in osteoclast numbers after regional irradiation of rats with carbon ions and gamma rays. Male Wistar rats were subjected to hind-leg irradiation with carbon ions (290 MeV/u) or gamma rays at doses of 15, 22.5, or 30 Gy. The effects of carbon ions and gamma rays on osteoclasts were studied using histologic and morphometric methods. At doses of 15 Gy and 22.5 Gy, osteoclast numbers increased transiently until day 5 after irradiation and then decreased rapidly in both the carbon ion and gamma ray irradiation groups. The carbon ion group showed reduced osteoclast size compared with the gamma ray group. Carbon ion irradiation had a more marked effect on osteoclast activity, and suppressed maturation to a greater extent than gamma irradiation. These observations suggest that carbon ion irradiation induces differential modulation of osteoclast growth factor expression.

Changes in bone volume after irradiation with carbon ions.

The effects of carbon ions on bone volume were studied by histological and morphometrical methods. Anesthetized rats irradiated with three different single doses (15, 22.5, or 30 Gy) of either carbon ions or gamma rays were sacrificed (5 rats/group) at 10 time points together with non-irradiated controls. Carbon ion-induced bone responses were qualitatively and quantitatively different from those induced by gamma irradiation at the same dose level. Irradiation with carbon ions resulted in a dose-dependent increase in bone volume, while gamma irradiation induced loss of bone volume, which was found to be independent of dose in the range studied over the same time course. After irradiation with carbon ions, bones showed thickening of the trabeculae, and the bone marrow became fibrous with fewer vessels. Carbon ion irradiation showed a greater effect on the bone-absorbing capability of osteoclasts than gamma irradiation. These observations suggest that irradiation with carbon ions may produce differential modulation of radiation-induced growth factor expression.