[Considerations of the classification and treatment for fused teeth]

Fused teeth were a phenomena of teeth anomalies in shape, which can affect the dental teeth both in primary and permanent dentition. Fused teeth do not only cause problems on crowding of dentition, abnormal occlusion and aesthetic, but also increase risks of dental caries, endodontics diseases, periapical diseases and periodontal diseases. Fusion of deciduous teeth may lead to abnormality of subsequent permanent teeth. Treatment of fused teeth may require multidisciplinary approach in endodontics, periodontics, oral and maxillofacial surgery, prosthodontics and orthodontics. The aim of the present article is to review the etiology, classification, clinical manifestations and treatment of fused teeth in order to provide dental clinicians with a reference of clinical management for fused teeth.

[Etiology and pathogenesis of internal root resorption]

Internal root resorption is a pathologic phenomenon with a characterization of the intraradicular dentin destruction due to the abnormal activities of odontoclasts. With its insidious pathology, internal root resorption can progress to a great extent before its clinical detection. The etiology and natural history of internal root resorption are uncertain and the associated key molecular pathogenesis have not been understood completely. The resorption is usually initiated by a stimulus with the loss of the protective predentin and progressed by the continuous stimuli of pulp infection. Various factors including trauma, chronic inflammation of the pulp, pulpotomy and tooth transplantation have been proposed for the occurrence of internal root resorption. The present paper reviews the etiology and pathogenesis of internal root resorption and provides guidance for the early intervention in the clinical practice.

[Prevention and treatment of root surface caries]

With the acceleration of population aging in China, the incidence of root surface caries is increasing year by year. Different from coronal caries, lesions of root surface caries mostly occur on the exposed root surfaces after gingival recession in elderly patients, mainly involving cementum and dentin. Root surface caries shows specificity in the pathogenic characteristics, clinical manifestations, diagnosis, treatment, and prevention. This review mainly summarizes the etiology and prevalence, pathology and clinical manifestations, classification, as well as three-level-prevention of root caries, in order to provide relevant guidance for the clinical prevention and treatment of root caries.

[Effects of Porphyromonas endodontalis lipopolysaccharides on the expression of matrix metalloproteinase-9 in mouse osteoblasts]

Objective: To evaluate the effects of lipopolysaccharides (LPS) extracted from Porphyromonas endodontalis (Pe) on the expression of matrix metalloproteinase-9 (MMP-9) mRNA and protein as well as enzyme activity in MC3T3-E1 cells and the role of nuclear factor-κB (NF-κB) in the process, so as to investigate the expression of MMP-9 dependent signaling pathways in mouse osteoblasts induced by Pe LPS. Methods: The experiment was conducted in 3 sessions: MC3T3-E1 cells were treated with various concentrations of Pe LPS (0-20 mg/L) and 10 mg/L Pe LPS for different time intervals (0-48 h). The expression of MMP-9 mRNA and protein were detected by real-time reverse transcription-PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), while the enzyme activity was detected by gelatin zymography method. The expression of MMP-9 mRNA was also detected in 10 mg/L Pe LPS treated MC3T3-El cells after pretreated with specific NF-κB inhibitor BAY 11-7082 for l h. Statistical analysis was performed using one-way ANOVA and Dunnett t test with SPSS 13.0 software package. Results: The levels of MMP-9 mRNA and protein increased significantly after the treatment with various concentrations of Pe LPS (0-20 mg/L), which indicated that Pe LPS induced osteoblasts to express MMP-9 in dose dependent manners. The expression of MMP-9 protein increased from (5 395±362) ng/L (blank control group) to (12 684±375) ng/L (20 mg/L group). Maximal induction of MMP-9 mRNA expression was found in the MC3T3-E1 cells treated with 10 mg/L Pe LPS for 24 h. The expression of MMP-9 mRNA in the 20 mg/L group was about 7 times than that in the blank control group. After 24 h, the expression of MMP-9 mRNA decreased. Maximal expression of MMP-9 protein was found in the MC3T3-E1 cells treated with 10 mg/L Pe LPS for 48 h ([35 055±2 346] ng/L) showing the highest enzyme activity. The mRNA of MMP-9 decreased significantly after pretreatment with 10 µmol/L BAY 11-7082 for 1 h. Conclusions: Pe LPS might induce the expression of MMP-9 in MC3T3-E1 cells through the signaling of NF-κB.

Characterization and expression analysis of a cyclin B gene from black tiger shrimp (Penaeus monodon)

The open reading frame of black tiger shrimp (Penaeus monodon) cyclin B (Pmcyclin B) was identified, based on cDNA sequence registered in GenBank (accession No. EF015590). The target sequence was 1206 bp, corresponding to 401 amino acids. Two conserved signature sequences of the cyclin B gene family were found in the Pmcyclin B deduced aa sequence. Temporal expression of Pmcyclin B in different tissues, including ovary, lymphoid organ, brain, blood, muscle, heart, gill, hepatopancreas, and intestine, were quantified by quantitative real time PCR. Messenger RNA expression levels of Pmcyclin B were greatest in the ovary, compared to other tissues (P < 0.05). Temporal expression of Pmcyclin B in the ovary at six different developmental stages was investigated by real-time PCR; no significant difference was observed (P < 0.05). Recombinant Pmcyclin B protein and its polyclonal antibody were successfully produced. Western blot analysis revealed differential expression of Pmcyclin B in ovaries in developmental stages II to IV; a positive signal (45 kDa) was observed in all ovarian stages assessed, but was most intense at stage III. Pmcyclin B protein was assessed by immunohistochemistry and was localized to the cytoplasm of prophase oocytes at stage II and enriched in the nuclei of pro-metaphase oocytes at stages III and IV. Results from this study indicate that Pmcyclin B is constitutively expressed and plays an important role in ovarian maturation in P. monodon.

Characterization of ORF127 of Helicoverpa armigera nucleopolyhedrovirus

It has been shown that Ha127 in the genome of Helicoverpa armigera nucleopolyhedrovirus (HaNPV) has homologs in some other baculoviruses and encodes a putative protein of 192 aa. In this study, a sequence analysis showed the transcription initiation site in Ha127 gene at nts 188 upstream of the translation initiation codon ATG and a potential leucine zipper motif at aa 34-55 in the corresponding protein. Ha127 transcripts were detected in HaNPV-infected HzAM1 cells at 18-72 hrs post infection ( p.i.) by RT-PCR, while the corresponding protein was found at 24-72 hrs p.i. by Western blot analysis suggesting that Ha127 is a late gene product. The size of detected Ha127 protein was about 28 K, a larger value than the predicted 22.6 K indicating a post-translational modification. Immunofluorescence assay of HzAM1 cells infected with HaNPV and Ha127-EGFP expression showed that Ha127 protein was localized in the nucleus. In summary, these data suggested that Ha127 was a functional ORF that might play a role in the nucleus during the late or very late gene expression.

IFN-gamma enhances paclitaxel-induced apoptosis that is modulated by activation of caspases 8 and 3 with a concomitant down regulation of the AKT survival pathway in cultured human keratinocytes

The aim of this study was to investigate the molecular effects of paclitaxel and IFN-gamma on cultured human keratinocyte cells (HaCaT) assessing the induction of both the apoptotic pathway and cell survival signals. Cellular cytotoxicity assays were performed by MTT dye assay. Caspases 8, 3 and AKT (Ser473 and Thr308 residues) were assessed by Western blot analysis. Morphological characteristics were examined by Wright stain analysis. Paclitaxel reduced keratinocyte growth in a 3-day bioassay with an effective ED(50) of 6-600 ng/ml. A large variation in ED(50) can be attributed to the asynchronous population of cells. Paclitaxel treatment induced activation of the AKT survival pathway in a time-dependent manner. The down-regulation of AKT signal was preceded by the subsequent activation of caspases 8 and 3 leading to apoptosis. These results indicate that paclitaxel activates both the PI3-K/AKT cell survival pathway followed by induction of apoptotic signals in cultured human keratinocytes. The induction of apoptosis in paclitaxel-treated cells is enhanced by coadministration of IFN-gamma. The synergistic effect of these two agents on HaCaT cells relies on a pathway involving caspases 8 and 3, with activity increasing by 48 h. Collectively, our data indicate that i) paclitaxel-induced apoptosis is enhanced by IFN-gamma; ii) the down-regulation of PI3-K/AKT survival pathway may help potentiate the apoptotic effects of paclitaxel and iii) the apoptotic signaling pathways are initiated with the activation of caspases 8 and 3 activities.