Effect of biofilm formation on virulence factor secretion via the general secretory pathway in Streptococcus mutans

Objectives

To investigate the role of SecA in protein secretion, and to evaluate the effect of biofilm formation on protein secretion in Streptococcus mutans.

Design

S. mutans strains UA159 and GS-5 were used in this study. Cells grown in biofilm and planktonic conditions were observed using immunogold electron microscopy. The mRNA levels of ftf, gtfB, gtfC, gtfD, Pac and secA were analysed in different growth conditions using real-time quantitative polymerase chain reaction. The levels of wall proteins and whole-cell protein extracts were examined using Western blot analysis.

Results

A microdomain colocalised with SecA and virulence factors such as Pac (AgI/II) and glucosyltransferase (GTF) was observed. The mRNA level of secA was upregulated in the biofilm condition. The level of protein expression of SecA and wall protein levels of GTF, fructosyltransferase (FTF) and Pac (AgI/II) in the biofilm condition were significantly higher than in the planktonic condition.

Conclusions

These data suggest that S. mutans utilises the Sec pathway to secrete virulence factor proteins such as Pac (AgI/II), GTF and FTF, and protein secretion occurred at a distinct microdomain. The level of SecA, the key factor in the Sec pathway, was influenced significantly by biofilm formation in S. mutans.     

Epithelial cells in PDL are critical in resuming the integral relation between tooth root and supporting bone after trauma--a transplantation experiment

OBJECTIVE: The aim of this study was to determine the response of the residual epithelial network following traumatic breakdown of the periodontal ligament (PDL). METHODS: Mandibular incisor sections with PDL (experimental) and sections denuded of PDL (control) from 4- to 6-week-old Wistar-Furth rats were transplanted into the defects created in the frontal bone of the recipient syngeneic rats. At intervals, the defects with implanted teeth roots were collected and processed for histological and biochemical examination. Immunolocalization of epithelial cells was performed to monitor their phenotypic changes during transplantation healing period. RESULTS: (1) Histological observation of the experimental sample revealed the sequence of cellular response characterized by an initial degeneration of PDL followed by a proliferation of granulation tissue. There was also a marked odontoblastic reaction with extensive deposition of regular dentine within the pulp chambers. In the control group, initial signs of bony fusion with dentine led to an extensive ankylosis and bone replacement between roots and defects. (2) Immunostaining indicated that, in experimental groups, the pattern of regularly spaced epithelial cells lying in close approximation to the root surface was distinct 10 days post-transplantation but became diminished afterwards. The immunoreaction against epithelial cells was negative in the control. CONCLUSION: Residual PDL is essential to prevent ankylosis after trauma and epithelial cells may facilitate the re-establishment of root-PDL-bone complex by transforming into mesenchymal cells.     

Physical properties of a system for direct acquisition of digital intraoral radiographs

Oral Radiology - To determine technical properties for a direct digital intraoral radiographic system, F1iOX (Fimet Oy, Moninkylä, Finland). A dose response function was calculated from seven...     

口腔颌面部肿瘤化疗方案药物敏感性试验

尊文以人舌鳞癌细胞系Ｔｃａ８１１３为对象，利用ＭＴＴ法对口腔颌面部肿瘤化疗常用的八种药物和七种方案进行了药敏试验，ＡＤＭ、５－Ｆｕ、ＣＤＤＰ等抗肿瘤作用较强；而ＰＹＭ、ＭＴＸ、ＶＣＲ单用对Ｔｃａ８１１３细胞无明显作用。化疗方案中以ＭＭＢＤ、ＰＦ、ＰＶＰ方案为佳，卡铂与顺铂在此疗方案中的作用无明显差异。实验结果提示：肿瘤化疗不能只凭经验用药，应注意化疗的耐药性问题。     

常用口腔医学英语缩略语及其意义Ⅱ口腔医学及其主要相关学科期刊刊名略语

由于刊名缩写简明，达意，节省籍幅，故而在国内外口腔医学及相关学科专业期刊参考文献中广泛采纳。通常在临床，教学及科研中，因某种目的常需从一篇原始文章或综述的参考文献中查找引用文献，无疑需要具备辨认参考文献中的刊名缩写，理解其全意的能力，     

Examination of the signal transduction pathways leading to upregulation of tissue type plasminogen activator by Porphyromonas endodontalis in human pulp cells

AIM: To investigate the tissue type plasminogen activator (t-PA) activity in human pulp cells stimulated with Porphyromonas endodontalis (P. endodontalis) in the absence or presence of p38 inhibitor SB203580, mitogen-activated protein kinase kinase (MEK) inhibitor U0126 and phosphatidylinositaol 3-kinase (PI3K) inhibitor LY294002. METHODOLOGY: The supernatants of P. endodontalis were used to evaluate t-PA activity in human pulp cells using casein zymography and enzyme-linked immunosorbent assay (ELISA). Furthermore, to search for possible signal transduction pathways, SB203580, U0126 and LY294002 were added to test how they modulated the t-PA activity. RESULTS: The main casein secreted by human pulp cells migrated at 70 kDa and represented t-PA. Secretion of t-PA was found to be stimulated with P. endodontalis during 2-day cultured period (P < 0.05). From the results of casein zymography and ELISA, SB203580 and U0126 significantly reduced the P. endodontalis stimulated t-PA production respectively (P < 0.05). However, LY294002 lacked the ability to change the P. endodontalis stimulated t-PA production (P > 0.05). CONCLUSIONS: Porphyromonas endodontalis enhances t-PA production in human pulp cells, and the signal transduction pathways p38 and MEK are involved in the inhibition of t-PA.     

术前正畸对骨性Ⅲ类错颌患者颞下颌关节影响的锥形束CT研究

目的 探讨术前正畸对行正畸-正颌联合治疗的骨性Ⅲ类错颌患者颞下颌关节（TMJ）的影响。方法 选取24例行正畸-正颌联合治疗的骨性Ⅲ类错颌患者,分别在术前正畸完成前后检查并记录关节症状,并行锥形束CT（CBCT）扫描,在三维方向测量髁突各径值（d）、髁突高度（h）、不同角度下关节间隙（L）、双侧髁突间距（R）及各髁突角度值,比较和分析不同时期TMJ症状及骨性结构的变化情况。结果 术前正畸前后关节症状无明显改变;颞下颌关节骨性结构在三维方向上的各测量指标均无显著变化（P>0.05）。结论 在正畸-正颌联合治疗过程中,术前正畸不会对患者TMJ产生明显影响。     

Association of vitamin D receptor gene polymorphisms in Chinese patients with generalized aggressive periodontitis

Background and Objective:  The clinical features suggest that genetic factors may have a strong influence on susceptibility to aggressive periodontitis. The aim of this study was to investigate the association of vitamin D receptor gene polymorphisms with generalized aggressive periodontitis in Chinese patients.
Material and Methods:  A restriction fragment length polymorphism (RFLP) for 10,438,141 C to T (rs1544410, Bsm I), 10,382,063 A to G (rs731236, Taq I), 10,382,143 C to A (rs7975232, Apa I) and 10,416,201 A to G (rs2228570, Fok I) of vitamin D receptor gene was analysed by polymerase chain reaction, followed by digestion with restriction enzymes and gel electrophoresis. The genotypes of 51 generalized aggressive periodontitis patients and 53 periodontally healthy control subjects were analysed. The genotypic and allelic frequencies of each polymorphism site for the patients and control subjects were compared.
Results:  The distribution of vitamin D receptor Fok I genotypes and alleles between the two groups was significantly different ( p =  0.043 and p  = 0.012, respectively). The F allele seemed to increase the susceptibility of aggressive periodontitis (odds ratio = 2.02, 95% confidence interval = 1.16–3.50) in Chinese patients. There was no significant difference in the genotype distribution or the allele frequencies of vitamin D receptor Bsm I, Apa I and Taq I between two groups.
Conclusion:  The study indicates that Fok I polymorphism of vitamin D receptor gene might be associated with generalized aggressive periodontitis in Chinese patients. In addition, the carriage of F allele increases the risk of developing generalized aggressive periodontitis.