The porphyromonas gingivalis prtP/kgp homologue exists as two open reading frames in strain 381

P- gingivalis is considered to be a major pathogen of adult periodontitis. Among its cadre of putative virulence factors are hemagglutinins (adhesins) and proteases. We here report the cloning, sequencing and characterization of two genes, designated kgp(381) and hagD. Kgp(381), an open reading frame (ORF) of 1095 bp encoding a 40.1 kda protein, has high homology to the proteolytic domain of cysteine protease/hemagglutinin genes. HagD, an ORF of 4077 bp encoding a 147.1 kda protein, contains one HArep sequence which establishes it as an additional member of the HArep multigene family. Although similar in sequence to kgp and prtP which were identified from strains HG66 and W12, respectively, the kgp(381)-hagD genes have several characteristics which distinguish them from kgp and prtP. Foremost among these is a single base difference which produces a termination codon and an immediate frame shift resulting in two ORFs in strain 381 as compared to one ORF in strains HG66 and W12. In addition, a 172 amino acid sequence near the C-terminal end of hagD has very low identity (20.5–27.8%) to the corresponding region of kgp and prtP. These demonstrate that the homologue of kgp and prtP in strain 381 occurs as two separate genes which may genetically separate the adhesive and enzymatic domains of Kgp and PrtP proteins. Reverse polymerase chain reaction (PCR) analysis indicates that hagD expression is regulated by hemin concentration.     

Carnoy液对金黄地鼠颊囊作用的研究

目的了解Carnoy液对粘膜组织损伤的性质，为其用于临床治疗提供理论依据。方法以金黄地鼠颊囊作为模型，以Carnoy液作为涂布试剂，药液作用时间为4min，于术后不同时期处死动物，切取标本，进行光镜和透射电镜观察。结果Carnoy液可引起颊囊粘膜上皮坏死脱落，溃疡形成，穿透深度约0.3mm。术后第3周坏死区上度重新形成，胶原纤维及成纤维细胞明显增多。结论Carnoy液是一种烧灼性质较强的物质，将其用于上皮性囊肿治疗，可因上皮破坏而治愈囊肿或降低其复发率。     

Metastases to lingual lymph nodes from squamous cell carcinoma of the tongue

The diagnosis of squamous cell carcinoma (SCC) of the tongue metastasising to the lingual lymph nodes is rare. Until now lingual lymph nodes have not been mentioned in any system of lymph node classification. We report a case of SCC of the tongue with metastases to the lymph nodes in the superficial floor of the mouth, and to levels I and II lymph nodes. We provide evidence of the existence of lingual lymph nodes, and validate the practice of removing the lymph node-bearing-tissue of the floor of the mouth during neck dissection in cancers of the oral cavity.     

Heterotrophic ossification on a skin graft in a postburn scar of the chin

Some patients who have heterotrophic ossification (HO) in a postburn scar are occasionally seen in the clinic. The occurrence of HO following hip and abdominal surgery is common in males, whereas females are frequently affected following burns. The HO of skin grafts in burn scars of the superior body parts is uncommon, especially on the face. We report a recent case of a male patient in whom HO arose on skin grafts on his chin. The patient presented with a history of a painless chin mass for 48 years. Computed tomography scan suggested that the mass was located within subcutaneous tissue away from the lower jaw. The density of the mass was almost the same as the cortical bone of the lower jaw. The mass was completely resected under general anesthesia. It was a rectangular mass of 3× 0.5× 0.3 cm. Histological examination gave the diagnosis of HO, which was also confirmed by immunohistochemical stainings for vimentin. Recurrence was not found in this case by clinical and radiologic follow-up at 1 year after surgery.     

Concurrence of replicative senescence and elevated expression of p16(INK4A) with subculture-induced but not calcium-induced differentiation in normal human oral keratinocytes

Primary normal human oral keratinocytes (NHOKs) undergo differentiation in the presence of calcium concentrations higher than 0.15 mM in vitro, which is useful in investigating the mechanisms involved in the differentiation of epithelial cells. Serial subculture of NHOKs to the postmitotic stage also induces terminal differentiation. However, the detailed mechanisms of both differentiation processes remain substantially unknown. To investigate the molecular differences in these processes, NHOKs were induced to differentiate by exposure to 1.2 mM of calcium and by serial subculture to the postmitotic stage. To study whether the cells were induced to differentiate and to undergo replicative senescence, the amount of cellular involucrin and the expression of senescence-associated beta-galactosidase (SA-beta-gal) were measured respectively. The expression of replicative senescence-associated genes and the activity of telomerase from the differentiated cells were also determined. Both calcium treatment and serial subculture to the postmitotic stage notably elevated the cellular involucrin. The percentage of SA-beta-gal-positive cells was significantly elevated by the continued subculture, but such changes were not observed in keratinocytes exposed to calcium. The concentration of cellular p16(INK4A) protein was progressively increased by the continued subculture but was not changed by calcium treatment. On the other hand, the concentrations of cellular p53 were similar in both differentiation processes. However, telomerase activity was lost in NHOKs that had undergone differentiation by both calcium treatment and serial subculture. The results indicate that calcium-induced differentiation of NHOKs has similar characteristics to their serial subculture-induced differentiation, but that the differentiation processes are not identical, because calcium-induced differentiation does not concur with either replicative senescence or the gradually increased concentration of p16(INK4A).     

Stress corrosion cracking of NiTi in artificial saliva.

OBJECTIVES: This paper aimed to study the mechanism of the cracking of orthodontic NiTi wire. METHODS: Two orthodontic NiTi wires were subjected: (1) optical and scanning electron microscopy (SEM) to observe the fracture surface; (2) energy dispersive X-ray spectroscopy to determine the composition of the surface product; (3) anodic polarization to remove the surface product. Samples of NiTi alloy were subjected to the constant loading test to study the stress corrosion cracking (SCC) behavior of NiTi shape memory alloy in artificial saliva. RESULTS: The results showed that there were three typical areas at the fracture surface of NiTi orthodontic wire. Area '1' was a tool-made notch. Crack initiated from the root of this notch and propagated to form Area '2', which was perpendicular to the wire axis and covered by surface film. This film consisted of Na, K, Cl, P, S and O except Ni and Ti. The cracking process of NiTi alloy under the constant loading test depended on the pH of saliva and applied stress. The crack length was about 262microm, the longest at 300MPa and pH 3.0. SIGNIFICANCE: A tool-made notch in orthodontic NiTi wires can cause SCC. At high stress and low pH, this NiTi alloy was most sensitive to cracking.     

种植义齿系统工程的概念及修复环节在其中的位置

种植义齿治疗是一个系统工程，需要医学专家、理工专家和患者的共同努力。其中，修复专家占有重要地位。他们需要根据患者的意愿和条件确定种植义齿是否可行，以及是否能给患者带来最大的利益。需要设计植入体的数量、部位和植入角度。需要根据种植体界面的特殊条件在义齿的设计制作中作相应的处理。还需要对患者作咨询教育，使之对种植义齿抱有合理的期望并遵医嘱执行保健措施。     

6 000 年前成人第三磨牙的研究

目的:观察距今约6 000年前成人第三磨牙的位置情况。方法:研究了200个半坡博物馆内保存的新石器时代人颌骨标本,第三磨牙共383颗(上颌187颗,下颌196颗),观察第三磨牙的萌出情况。第三磨牙未萌出者经X线片证实,按有无第三磨牙牙胚,将其分别归为埋伏阻生组或先天缺失组。结果:上颌第三磨牙先天缺失率为26.74%,下颌第三磨牙先天缺失率为17.35%。上颌第三磨牙阻生率为2.67%,下颌第三磨牙阻生率为14.79%。结论:现代人第三磨牙阻生率与先天缺失率均较新石器时代成人高,人类第三磨牙阻生与先天缺失是伴随整个人类进化而发生的咀嚼器官退化现象的一部分。     

Effect of adoptive transfer of antigen-specific B cells on periodontal bone resorption

BACKGROUND AND OBJECTIVES: Host immune responses to periodontal pathogens have been considered to contribute to the alveolar bone destruction in periodontitis. However, the role of B lymphocytes in the pathogenesis of periodontal bone loss is not clear. METHODS: We examined the effect of adoptive transfer of antigen-specific B cells from rat spleens on experimental periodontal bone resorption. Donor rats were immunized intraperitoneally (i.p.) with formalin-killed Actinobacillus actinomycetemcomitans. Antigen-specific B cells were prepared from splenocytes by first binding CD43(+) cells to Petri dishes coated with anti-CD43 antibody to remove T cells, and non-binding cells were passed through a nylon wool column to deplete accessory cells. The retained cells were then collected and bound to A. actinomycetemcomitans-coated Petri dishes for enrichment of A. actinomycetemcomitans-binding B cells (AAB). A. actinomycetemcomitans non-binding B cells (ANB) and B cells from non-immunized donor rats (NIB) were also collected from these procedures. Each type of B cell was injected into a group of recipient rats that were then orally infected with live A. actinomycetemcomitans. RESULTS: At termination, the antibody levels to A. actinomycetemcomitans in serum and gingival wash fluids were significantly higher in the recipients transferred with AAB when compared to the recipients transferred with ANB or NIB. A markedly elevated number of antibody-forming cells were observed in the spleens of the recipients transferred with AAB, and these recipient rats also exhibited significantly increased bone resorption when compared to the other groups. CONCLUSIONS: It is suggested that B cells can contribute to periodontal bone resorption and that antigen-triggering of B cells is required for the bone resorption.