[Analysis of distribution and contents of heavy metal pollution in fish body with laser-induced breaddown spectroscopy].

Environmental pollution can cause poisoning, disease and death of organisms, and the absorption and the accumulation of different biological tissues on pollutants are different. The absorption of heavy metal elements of various biological tissues on pollutants is an important biomedical research problem. In the present paper, a laser induced breakdown spectroscopy (LIBS) method was used to quantitatively analyze heavy metal elements in various tissues of some contaminated fish samples. Optimal experimental parameters were obtained in the LIBS experiments for these fish samples, calibration curves for plumbum and barium elements were fitted and the contents of heavy metal elements were determined with the external calibration approach. Experimental results showed that there was the heavy metal accumulation in fish liver mouth, and gills etc, however the heavy metal content in fish meat is very low. The proposed method can be used for the assessment studies of the influence of pollution on the organisms, and can be promoted in the biomedical fields.

[Research progress on the relationship between Porphyromonas gingivalis and the malignancy of the digestive system and possible pathogenetic mechanism].

The malignant tumors including oral cancer, colorectal cancer, pancreatic cancer, and esophageal cancer, of the digestive system are a common high-fatal malignancy. Porphyromonas gingivalis, as the most important pathogen of periodontal disease, has been gradually proved that its invasiveness occurs not only in the mouth but also in other parts of the digestive system. Moreover, the relevant pathogenic mechanism is increasingly attracting the reseachers' attention. In this study, the role and possible pathogenesis of Porphyromonas gingivalis in the digestive system are described in a systematic and comprehensive way.

[Effects of MMPs inhibitors on microleakage with wet bonding technique].

PURPOSE: To observe the effects of matrix metalloproteinases(MMPs) inhibitors on microleakage with wet bonding technique. METHODS: Twenty-seven premolars were randomly assigned to 3 groups. Class Ⅴ cavities were prepared in the neck of the teeth and treated with distilled water, 2% chlorhexidine (CHX) or 2% monocycline (MI) for 60 seconds. Resin was used to restore the prepared cavities following application of luting agent. Samples in each group were soaked for 1 h with 10% NaClO and then 2 layers of nail polish were applied, followed by treatment with 50wt% ammoniated silver nitrate (ASN), and developing solution in turn. Each tooth was sectioned longitudinally to 1~2 mm slices and examined with stereo microscope and scanning electron microscope (SEM). The data were analyzed with SPSS 16.0 software package for Wilcoxon rank sum test. RESULTS: There was varied microleakage at the margin. The difference was significant between group CHX and control group, between group MI and control group; However, there was no significant difference between group CHX and group MI. CONCLUSIONS: MMPs inhibitor can reduce microleakage with wet bonding technique.

[Evaluation of the effect for ffh gene silencing on the aciduricity of fluoride resistant Streptococcus mutans].

PURPOSE: To analyze the effect of ffh gene silencing on the aciduricity of fluoride resistant Streptococcus mutans in vitro. METHODS: By using electroporation, UA159-FR was transformed and combined with targeted site of ffh gene sequence, and the best piece of siRNA for fluoride resistant Streptococcus mutans was screened. In different values of pH of BHI, they were cultured for 24 hours with UA159-FR respectively, and then centrifugated to determine the pH and OD600. SPSS17.0 software package was used to analyze the data. RESULTS: The aciduricity of UA159-FR had significant differences compared with ffh gene silencing for UA159-FR in δpH (P<0.05), and the former was higher than the latter. At pH=3.5-5.0, P<0.01; at pH=5.5-7.5, P<0.05. Significant differences were noted in OD600 and their growth tendency were similar. CONCLUSIONS: The aciduricity of fluoride resistant Streptococcus mutans has significant effect when the ffh gene is silenced.

[Clinical study on glass fiber-reinforced post applied in the restoration of residual crown and root of posterior teeth].

PURPOSE: The aim of this prospective randomized controlled trial is to evaluate the clinical effect of glass fiber-reinforced post core applied in the restoration of premolar or molar residual crown and root. METHODS: 195 residual crown and root of posterior teeth from 100 patients, aged from 18 to 60 years, were included in the study. Among 195 teeth, 95 teeth in the experimental group were restored with glass fiber-reinforced post core, while the other 100 teeth in the control group were restored with metal cast post core. All the teeth were then restored with porcelain fused metal crown. The esthetical property, function, and survival rate of the prostheses were observed. The data was analyzed with SPSS13.0 software package for X(2) test. RESULTS: The prostheses were followed up in this clinical study for a period of up to 36 months. In the experimental group, there were a total of 90 teeth with excellent chewing function, no complaint of discomfort, no debounding, no gingivitis or periapical periodontitis. The success rate of the experimental group was 94.74%, while that of the control group was 85.00%. The difference of the success rate between two groups was statistically significant(P<0.05). CONCLUSION: Glass fiber-reinforced post core can be used as an ideal restoration material for the premolar or molar residual crown and root.