远缘链球菌中葡萄糖基转移酶催化活性区基因的克隆和初步表达

目的 :构建一株高效表达Streptococcussobrinus 6715中GTF -I催化活性区 (含有B细胞表位 )多肽的菌株 ,为抗GTF -I的单克隆抗体的检测和防治龋病亚单位疫苗的研究奠定基础。方法 :提取基因组DNA ,然后用PCR技术扩增出中目的肽段的约 1.1kb编码基因 ,并将其克隆至表达载体 pGEX -4T -1中构建 pGEX -gtf表达质粒。该质粒转化大肠杆菌JM 10 9后获得重组表达菌株。PCR筛选阳性克隆子。异丙基-β -D -硫代半乳糖苷 (IPTG)诱导 ,确定含有 pGEX -gtf的大肠杆菌JM 10 9的表达情况。 结果 :含有质粒pGEX -gtf的大肠杆菌JM 10 9能够表达GST -GTF融合蛋白。 结论 :成功扩增目的基因 ,并且把它定向克隆到表达载体pGEX -4T -1中构建表达质粒 ,并且该表达质粒能在大肠杆菌中进行表达     

激光照射对牙髓细胞形态的影响

不同的激光能量可以产生不同的生物效应．本文应用扫描电镜、倒置显微镜观察不同能量、不同频率的激光能量设置对牙髓细胞形态的影响，结果表明：１００ｍｊ２０Ｈｚ、６０ｍｊ４０Ｈｚ、４０ｍｊ５０Ｈｚ以上的能量设置可使牙髓细胞产生裂纹、结构模糊．结论：Ｎｄ：ＹＡＧ激光的能量、频率均可影响牙髓细胞形态     

金属钛种植体表面蛋白吸附动力学研究

本章应用简单的称重法对等温吸附曲线和吸附动力学曲线进行了粗略的测定，并应用先进的XPS技术对蛋白质在不同pH值下的解吸特性进行研究。发现材料表面的蛋白吸附量随蛋白溶液的浓度的增加和时间的延长而增加，而且在浸泡最初的吸附量增加最快，尤其在前20分钟，吸附几乎就达到了平衡．还发现钛种植体表面的吸附的能力比317L不锈钢的吸附能力强，几乎同时进入吸附的平衡阶段。在体液pH值状态下，钛表面的蛋白吸附量最高，随着pH值向两侧移动，钛表面的蛋白吸附量在下降，而当pH值为25和12时，表面蛋白吸附量降至最小值，pH值继续升高或降低反而表面蛋白的残余量有所升高。     

Non-viral-mediated gene therapy approaches for bone repair

OBJECTIVES: Bone repair strategies continue to be developed for alternatives to autografting, allogeneic implants of banked bone, and other bone substitutes. Efforts have included the delivery of potent growth and/or differentiation factors and the use of gene therapy. For bone regeneration, gene therapy is the delivery, uptake and expression of DNA that has been localized to a wound bed. The objective of the current study is to investigate methods to enhance non-viral-mediated means of gene uptake and expression for use in bone regeneration. METHODS: Several types of DNA-polymer complexes, either applied directly to baby hamster kidney (BHK) cells, or released from a porous, resorbable gene-activated matrix (GAM), were evaluated in vitro for their ability to transfect cells with a circular plasmid DNA construct expressing green fluorescent protein. Complexes included conjugates containing a lipophilic reagent, liposomes, poly-ethyl-oxazoline, and poly-ethyleneimine (PEI). Data were subjected to analysis of variance and Fisher's protected least significant difference for multiple comparisons with significance established at p < 0.05. RESULTS: Transfection efficiencies of the liposome and PEI complexes improved in vitro when released from resorbable GAMs. The lipophilic reagent FuGene 6 demonstrated abundant uptake and expression in the initial 1- and 2-day evaluation periods. In contrast, the DNA-liposome and PEI GAM complexes demonstrated a sustained release, uptake and expression by the BHK cells at the 2-, 4-, and 7-day, and 4- and 7-day evaluation intervals, respectively. CONCLUSION: GAM technology appears to improve the functional stability and release duration of incorporated DNA-polymer complexes in the present in vitro studies. The ongoing objective of our research is to develop a localized treatment to improve the uptake and expression of plasmid DNA by non-viral-mediated gene therapy.     

Protease-active extracellular protein preparations from Porphyromonas gingivalis W83 induce N-cadherin proteolysis, loss of cell adhesion, and apoptosis in human epithelial cells

BACKGROUND: The protease-induced cytotoxicity of P. gingivalis may partly result from alteration of the extracellular matrix and/or surface receptors that mediate interaction between the host cells and their matrix. While P. gingivalis-induced degradation of E-cadherin has been documented, there is no information on the effects of P. gingivalis proteases on other members of this family of cell adhesion proteins. METHODS: Human epithelial KB cells were exposed to protease-active extracellular protein preparations from isogenic mutants of P. gingivalis. Quantification of apoptosis was performed by visualization of nuclei stained with 4,6'-diamidino-2-phenylindole. Alteration of cell adhesion proteins was examined by immunoblotting of cell lysates using monoclonal antibodies to those proteins. RESULTS: Treated cells exhibited loss of cell adhesion properties with apoptotic cell death subsequently observed. These effects correlated with the different levels of cysteine-dependent proteolytic activities of the isogenic mutants tested. Cleavage of N-cadherin was observed in immunoblots of lysates from detached cells. There was a direct correlation between the kinetics of N-cadherin cleavage and loss of cell adhesion properties. Loss of cell adhesion, as well as N-cadherin cleavage, could be inhibited by preincubation of P. gingivalis protease active extracellular protein preparations with the cysteine protease inhibitor TLCK. In control experiments, the cleavage of N-cadherin was detected after treatment of KB cells with trypsin but not after cell dissociation by a non-enzymatic method. CONCLUSIONS: These results suggest that extracellular proteases from P. gingivalis can induce degradation of N-cadherin, which could have implications for the pathogenicity of this bacterium.     

Transient loss of power of accommodation in 1 eye following inferior alveolar nerve block: report of 2 cases

Unintended intravascular injection from inferior alveolar nerve blocks can result in frustrating distant complications affecting such structures as the middle ear and eyes. Possible complications affecting the eyes include blurring of vision, diplopia, mydriasis, palpebral ptosis and amaurosis (temporary or permanent). In this article, we present a complication that has been reported only rarely. Two patients developed transient loss of power of accommodation of the eye resulting in blurred vision after routine inferior alveolar nerve blocks on the ipsilateral side. Clear vision returned within 10-15 minutes after completion of the blocks. The possible explanation for this phenomenon is accidental injection into the neurovascular bundle of local anesthetic agents, which were carried via the blood to the orbital region. This resulted in paralysis of a branch of cranial nerve III, the short ciliary nerves that innervate the ciliary muscle, which controls accommodation.     

口腔粘膜良性淋巴组织增生症的临床病理和免疫组化分析

目的明确口腔粘膜良性淋巴组织增生症（BLOM）的临床病理特征及其本质。方法收集分析6例BLOM的临床病理资料，并进行文献复习；对该组病例的组织标本进行免疫组化研究。结果发生在唇部和其它口腔解剖部位的口腔粘膜良性淋巴组织增生症的临床表现和诊断各有其特点；B淋巴细胞是淋巴滤泡和浸润炎症细胞的主要细胞万分。结论BLOM分为唇型和非唇型两种临床类型；BLOM是一种B淋巴细胞介导的增殖性局部体液免疫反应疾病。     

Root coverage with enamel matrix derivatives

Different root coverage procedures have been used to treat cases of gingival recession defects involving single or multiple exposed root surfaces. A therapeutic advantage may be gained if periodontal regeneration is obtained in addition to coverage of the root with gingiva. This article describes the treatment of gingival recession by combining a surgical technique with an enamel matrix derivative.     

Immunohistochemical demonstration of epithelial glutathione S-transferase isoenzymes in normal, benign, premalignant and malignant human oral mucosa

The expression and localization of glutathione S-transferase (GST) isoenzymes in the epithelium of normal oral mucosa ( n = 9), overlying reactive fibrous hyperplasia ( n =9), and of potentially malignant [leukoplakia ( n =25), submucous fibrosis ( n =12), verrucous hyperplasia ( n =16)] and malignant [squamous cell carcinoma ( n =36), verrucous carcinoma ( n =13)] oral lesions were examined immunohistochemically using polyclonal antibodies raised against GST isoenzymes (alpha, mu and pi) with the standard avidin-biotin-peroxidase complex (ABC) method. GST alpha, mu and pi were almost completely absent in the epithelium of normal oral mucosa and overlying benign fibrous tissues. GST alpha staining was cytoplasmic and focally positive, while GST mu staining was similar to but weaker than that seen for GST alpha. GST pi showed both cytoplasmic and nuclear staining and was expressed in 60% of leukoplakias with mild dysplasia ( n =15), 80% of leukoplakias with moderate to severe dysplasia ( n =10). 75% of submucous fibrosis samples ( n =12), 75% of verrucous hyperplasias ( n =16), 77% of verrucous carcinomas ( n =13), 81% of well-differentiated squamous cell carcinomas ( n = 26) and 70% of moderate- to poorly-differentiated squamous cell carcinomas ( n =10). In addition, GST pi expression was independent of the state of differentiation of oral cancers. Since GST pi was significantly over-expressed in the oral premalignant and malignant lesions, the kinetics of GST pi-positive cells and the value of GST pi as a tumor marker in oral carcinogenesis need further investigation.