Screening and detection of antimicrobials from Dai pharmaceuticals against clinical diseases by methicillin-resistant Staphylococcus aureus

Oroxylum indicum is one of the valuable Dai pharmaceuticals; the dry seeds and bark of O. indicum were used to treat acute cough, sore throat and so on. Of the seven compounds from O. indicum were determined and obtained using the bioassay-guided method. Among them, compound 7 was obtained from the plant for the first time. Eight bacterial strains and one yeast fungi were exposed to the compounds. Minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) or minimum fungicidal concentrations were determined according to the standard broth microdilution method. Baicalein (2) exhibited relative strong antibacterial activities with MIC of 8 μg ml^-1 and MBC of 16 μg ml^-1 against three MRSA strains of Staphylococcus aureus of SCCmec III type, whereas flavonoids 3, 5 and 7 showed some degree of activities against methicillin-susceptible S. aureus (MSSA, ATCC 25923). The findings may offer new evidence that why O. indicum was used widely in Dai peoples' life.

The effect of thermocycling and dentine pre-treatment on the durability of the bond between composite resin and dentine

The high bond strength between restorative resin and dentine plays an important role in long-term performance of restorations in the oral environment. A variety of treatment techniques have been described to enhance the bond strength of composite resin to dentine. Unfortunately, few studies have reported available bond durability of adhesive resins to dentine. The purpose of this research was to study the shear bond strength of composite resin to dentine pre-treated with phosphoric acid, self-etching agent or Nd:YAP laser irradiation. The durability of bond strength between resin and dentine stored in the artificial saliva thermocycling between 5 and 55 degrees C was also evaluated. The scanning electron microscope was used to assess the treated-dentine surfaces. The mean value of the shear bond strength in the acid-etching group (18.2 +/- 4.9 MPa) was the highest among the three dentine treatments (self-etching system: 12.6 +/-3.0 MPa, Nd:YAP laser: 13.4 +/- 3.3 MPa) prior to thermocycling. After thermocycling, shear strength values of all treated dentines decreased with increasing number of the cycles. When subjected to 3000 thermocycles, the mean bond strengths of these pre-treated samples to composite resin became 9.1 +/- 1.4, 7.8 +/- 1.8, and 8.1 +/- 1.7 MPa for acid-etching, self-etching and laser-irradiation, respectively, with a significant reduction of 38-50%.

Antimicrobial activity of four root canal sealers against endodontic pathogens

The antibacterial effects of various types of widely used endodontic sealers have not been compared systematically on facultative or obligate anaerobic endodontic pathogens. The aim of this study was to evaluate the antimicrobial properties of four commonly used endodontic sealers: two epoxy-resin-based sealers (AH26, AH plus), one zinc-oxide eugenol-based sealer (N2), and one calcium hydroxide-based sealer (Sealapex). The testing microbes were four facultative anaerobic species (Streptococcus mutans, Streptococcus sanguis, Escherichia coli, and Staphylococcus aureus) and four obligate anaerobic species (Porphyromonas gingivalis, Porphyromonas endodontalis, Fusobacterium nucleatum, and Prevotella intermedia). The freshly mixed sealers were placed into the prepared wells of agar plates inoculated with the test microorganisms. After varying periods of incubation (2 days for facultative anaerobic species and 7 days for obligate anaerobic species), the zones of growth inhibition were observed and measured. All the sealers were distinctly different from each other in their antimicrobial activity. The sealers showed different inhibitory effects depending on the types and bacterial strains. N2 containing formaldehyde and eugenol proved to be the most effective against the microorganisms. The extreme antimicrobial potency of this root canal sealer must be weighted against its pronounced tissue toxic effect.

The effect of sodium hypochlorite and chlorhexidine on cultured human periodontal ligament cells

OBJECTIVE

The objective of this study was to examine the effects of sodium hypochlorite (NaOCl) and chlorhexidine (CHx) on cultured human periodontal ligament (PDL) cells in vitro.

STUDY DESIGN

The effects of irrigation solutions on human PDL cells were evaluated by propidium iodide fluorescence cytotoxicity assay, protein synthesis assay, and mitochondrial activity.

RESULTS

Both NaOCl and CHx were cytotoxic to human PDL cells in a concentration- and contact time-dependent manner. In addition, CHx inhibited protein synthesis in human PDL cells. Although NaOCl displayed cellular cytotoxicity, it showed no protein inhibition in the PDL cells. Furthermore, both NaOCl and CHx exhibited an inhibitory effect on mitochondrial activity on human PDL cells.

CONCLUSIONS

This study suggests that these irrigation fluids may cause detrimental effects on vital tissues. Its clinical significance, however, needs to be evaluated further because concentration used, exposure time to the agent, and exposure surface area are important factors affecting the resulting effect.

Cytotoxic evaluation of root canal filling materials on primary human oral fibroblast cultures and a permanent hamster cell line

To date there has been very little data on the cytotoxic response of different cell lines to root canal sealers. The objective of this study was to determine the cytocompatibility of three different extracts of root canal sealers and to compare the cytotoxic response of these materials on two different primary human oral fibroblasts (derived from gingiva and buccal mucosa) and one permanent hamster cell line (V79 cells). Cytotoxicity was judged using an assay of tetrazolium bromide reduction. The results showed that root canal sealers (AH plus, Canals, and N2) were cytotoxic to primary human oral fibroblast cultures and V79 cells. It was found that N2 was the most toxic root canal sealer among those tested in all cultures. The toxicity decreased in an order of N2 > AH plus approximately = Canals. The sensitivity of toxicity depended on the materials tested and the cell culture system used.

Cytotoxic effects of denture base materials on a permanent human oral epithelial cell line and on primary human oral fibroblasts in vitro

PURPOSE

The objective of this study was to determine the cytocompatibility of three different extracts of denture base resins and to compare the cytotoxic effect of these materials on a human oral epithelial KB cell line and primary human oral fibroblasts derived from buccal mucosa.

MATERIALS AND METHODS

Set specimens from a heat-cured resin, a self-cured resin, and a light-cured resin were eluted with culture medium for 1, 3, and 5 days. Cytotoxicity was judged using tetrazolium bromide reduction assay.

RESULTS

The eluates from self-cured, heat-cured, and light-cured denture base resins were cytotoxic to primary human buccal fibroblast cultures and KB cells. Self-cured resin was the most toxic denture base material among the chemicals tested in all cultures. The cytotoxicity decreased in the order of self-cured resin > heat-cured resin > light-cured resin for KB cells. The rank for buccal fibroblast cells was self-cured resin > heat-cured resin > light-cured resin.

CONCLUSION

The influence of the cytotoxicity depended on the materials tested and the cell culture system used. The use of both permanent and primary cells is recommended for a better screening of the cytotoxic effects of denture base resins.

[Observation on sex-linkage inheritance of skin color in some local breeds of chicken]

The sex-linkage inheritance of skin color was observed in some local breeds of chicken. The results showed that there was a pair of melanin genes PP in autosomes in Taihe Silky Fowl, an Id gene in sex chromosome in Xianju Fowl, Xiaoshan Fowl and Beijing You Fowl, and an id gene in sex chromosome in Langshan Fowl, Gushi Fowl and Taihe Silky Fowl, respectively. The offspring produced by crossing of Taihe Silky Fowl(Male) with the fowl(Female) carrying Id gene (such as Xianju Fowl, Xiaoshan Fowl and Beijing You Fowl) can autosexingly determinate by skin color, male chicken has yellow skin, female chicken has black skin.

Cytotoxic and nongenotoxic effects of phenolic compounds in human pulp cell cultures

Phenolic compounds are widely used in clinical dentistry as sedatives for the dental pulp, as disinfectants for caries, and as root canal medications. The pathobiological effects of various phenolic compounds on human dental pulp fibroblasts were investigated with Hoechst 33258 fluorescence assay and DNA precipitation assay. All phenolic compounds showed cytotoxicity in Hoechst 33258 fluorescence assay by inhibiting cellular DNA in a concentration-dependent manner. The 50% inhibition concentrations required to decrease the cellular DNA contents by guaiacol, phenol, eugenol, and thymol were 9.8, 4.5, 0.9, and 0.5 mM, respectively. However these phenolic compounds did not cause DNA single-strand breaks in cultured human pulp fibroblasts. These results indicate that phenolic compounds are cytotoxic agents but are without genotoxic effects on human pulp fibroblasts in vitro. However care should be taken to reduce the possibility of pulpal as well as periapical irritations from inadvertent extrusion of these substances in clinical usage.

In vitro evaluation of the cytotoxicity and genotoxicity of root canal medicines on human pulp fibroblasts

An intracanal medicine is often required because microorganisms in the dentinal tubes may be difficult to eliminate completely by instrumentation. Phenolic compounds are widely used in dental treatment as sedatives for the dental pulp or as disinfectants for caries and the root canal. In this study, propidium iodide fluorescence and DNA precipitation assay were used to investigated the cytotoxic and genotoxic effects of camphorated phenol and camphorated parachlorophenol on cultured human pulp fibroblasts in vitro. Both medicines reduced the content of double-stranded polynucleic acid of fibroblasts over a 24-h culture period in a concentration-dependent manner. Camphorated parachlorophenol was more cytotoxic than camphorated phenol. But, both medicines did not cause genotoxicity on pulp cells. The advantage of these experimental methods are simplicity and rapidity. Furthermore, this experimental system may be useful for preliminary cytotoxicity and genotoxicity screening of various dental medicines in vitro.

[Correction of complete blepharoptosis with suspension by Frontalis aponeurosis flap]

The surgical corrective result of complete blepharoptosis is often uncertain. With suspension by Frontalis aponeurosis flap under the brow, the author treated 73 cases satisfactorily, the results conforming to Fox's criteria of a normal eyelid. The incision is made in the skin and Orbicularis oculi at the double-fold of the eyelid, and a muscle flap 2 cm wide is separated from under the Orbicularis oculi at the brow in the conjunction of Orbicularis oculi and Frontalis. The flap is fixed to the tarsus, and a strip of redundant skin 2-3 mm wide excised. The incision is closed with intermittent sutures.