Expression of nonclassical MHC class Ib genes

Peptide binding proteins of the major histocompatibility complex consist of the “classical” class Ia and “nonclassical” class Ib genes. The gene organization and structure/function relationship of the various exons comprising class I proteins are very similar among the class Ia and class Ib genes. Although the tissue-specific patterns of expression of these two gene families are overlapping, many class Ib genes are distinguished by relative low abundance and/or limited tissue distribution. Further, many of the class Ib genes serve specialized roles in immune responses. Given that the coding sequences of the class Ia and class Ib genes are highly homologous we sought to examine the promoter regions of the various class Ib genes by comparison to the well characterized promoter elements regulating expression of the class Ia genes. This analysis revealed a surprising complexity of promoter structures among all class I genes and few instances of conservation of class Ia promoter regulatory elements among the class Ib genes.     

中国版纳猪MHCI类P1分子全长的原核表达与纯化

目的：获得原核表达的中国版纳猪ＳＬＡＩ类Ｐ１蛋白质分子。方法：ＰＣＲ扩增去信号肽的ＳＬＡＩ类Ｐ１ｃＤＮＡ序列，亚克隆至ｐＧＥＭＴ载体，测序。将亚克隆的Ｐ１　ｃＤＮＡ片段插入表达载体ｐＥＴ４２ｂ（＋），构建重组表达质粒ｐＥＴ－４２ｂ（＋）／ｓｌａ－ｐｌ，转化Ｅ·ｃｏｌｉ表达菌 ＢＬ２１－ＣｏｄｏｎＰｌｕｓ（ＤＥ３）－ＲＩＬ，ＩＰＴＧ诱导 Ｐ１－８ ｘ ｈｉｓ融合蛋白表达，经包涵体洗涤，８ ｍｏｌ／Ｌ尿素变性溶解，Ｎｉ２＋亲和层析，梯度透析后，定量保存。ＳＤＳ－ＰＡＧＥ、ｗｅｓｔｅｒｎ－ｂｌｏｔｔｉｎｇ鉴定目的蛋白的表达与纯化。结果：目的蛋白（分子量３９．５ ｋＤ）表达量占细菌总蛋白 １５％，每升表达菌获得纯度９５％的目的蛋白 ４０ ｍｇ～６０ｍｇ。结论：成功建立猪 ＳＬＡ分子全长原核表达、纯化体系，为建立间接识别猪移植抗原ＳＬＡＩ类分子的人Ｔ细胞系及表位分析打下基础。     

Anti-Soluble Liver Antigen (SLA) Antibodies in Chronic HCV Infection

Hepatitis C infection is associated with autoimmune disorders, such as the production of autoantibodies. Anti-LKM1 and anti-LC1, immunomarkers of type 2 autoimmune hepatitis, have been previously associated with a HCV infection. Anti-Soluble-Liver-Antigen autoantibodies (SLA) are specifically associated with type 1 and type 2 autoimmune hepatitis and more closely related to patients who relapse after steroid therapy. The recent molecular cloning of the soluble liver antigen provides the opportunity to develop more specific tests for the detection of antibodies against it. The aim of this work is to characterize anti-soluble-liver autoantibodies in sera from patients chronically infected by HCV. A recombinant cDNA from activated Jurkat cells coding for the full length tRNP^(Ser)Sec/SLA antigen was obtained. ELISA, Western Blot and immunoprecipitation tests were developed and used to search for linear and conformational epitopes recognized by anti-SLA antibodies in sera from patients chronically infected by HCV. Anti-soluble liver antigen antibodies were found in sera from 10.4% of HCV-infected patients. The prevalence was significantly increased to 27% when anti-LKM1 was also present. Most anti-SLA reactivity was directed against conformational epitopes on the antigen. The means titers by ELISA were lower than those obtained in type 2 AIH. The result of autoantibody isotyping showed a subclass restriction to IgG1 and also IgG4. This study shows the presence of anti-SLA antibodies in approximately 10% of HCV infected patients. The prevalence of SLA autoantibodies in HCV infected patients increases when LKM1 autoantibodies are also present. The relationship between the prevalence of this characteristic autoimmune hepatitis autoantibody and the implication of an autoimmune phenomenon in the liver injury of patients chronically infected by HCV needs further investigation.     

Atomic layout of an orthodontic titanium mini-implant in human tissue: Insights into the possible mechanisms during osseointegration

Objectives:To evaluate nanoscale molecular interactions in the interface between human bone and orthodontic titanium implants.Materials and Methods:An orthodontic implant (sandblasted with large grit and with an acid-etched surface treated with Ti6A14V alloy) retrieved from the mandible of human after 2 months of healing was used to analyze the molecular interactive mechanism between the implant and the surrounding bone tissue. To preserve the natural state of the sample as much as possible, cryofixation and scanning electron microscope/focused ion beam milling without any chemical treatment were used during sample preparation. Atom probe tomography was used to investigate the chemical composition and structure at the interface between the implant and human bone tissue.Results:Three-dimensional (3D) reconstruction of the whole sample revealed a 20 × 50-nm² plate-like bony element diffusion layer in the sample. The iso concentration analysis of the diffusion layer indicated that the bony element, calcium, and the implant element, titanium oxide, were interspersed with each other. Detailed ionic distribution was illustrated by 3D reconstruction with partial region of interest and one-dimensional concentration profiles of the implant-bone interface.Conclusions:The study results advance nanoscale understanding of osseointegration and suggest a potential nanostructure for increasing bond strength of biomaterials to bone.     

Accuracy of computer-aided design/computer-aided manufacturing–generated dental casts based on intraoral scanner data

Background.Little is known about the accuracy of physical dental casts that are based on three-dimensional (3D) data from an intraoral scanner (IOS). Thus, the authors conducted a study to evaluate the accuracy of full-arch stereolithographic (SLA) and milled casts obtained from scans of three IOSs.Methods.The authors digitized a polyurethane model using a laboratory reference scanner and three IOSs. They sent the scans (n = five scans per IOS) to the manufacturers to produce five physical dental casts and scanned the casts with the reference scanner. Using 3D evaluation software, the authors superimposed the data sets and compared them.Results.The mean trueness values of Lava Chairside Oral Scanner C.O.S. (3M ESPE, St. Paul, Minn.), CEREC AC with Bluecam (Sirona, Bensheim, Germany) and iTero (Align Technology, San Jose, Calif.) casts were 67.50 micrometers (95 percent confidence interval [CI], 63.43-71.56), 75.80 μm (95 percent CI, 71.74-79.87) and 98.23 μm (95 percent CI, 94.17-102.30), respectively, with a statistically significant difference among all of the scanners (P < .05). The mean precision values were 13.77 μm (95 percent CI, 2.76-24.79), 21.62 μm (95 percent CI, 10.60-32.63) and 48.83 μm (95 percent CI, 37.82-59.85), respectively, with statistically significant differences between CEREC AC with Bluecam and iTero casts, as well as between Lava Chairside Oral Scanner C.O.S. and iTero casts (P < .05).Conclusion.All of the casts showed an acceptable level of accuracy; however, the SLA-based casts (CEREC AC with Bluecam and Lava Chairside Oral Scanner C.O.S.) seemed to be more accurate than milled casts (iTero).Practical Implications.On the basis of the results of this investigation, the authors suggested that SLA technology was superior for the fabrication of dental casts. Nevertheless, all of the investigated casts showed clinically acceptable accuracy. Clinicians should keep in mind that the highest deviations might occur in the distal areas of the casts.     

成骨分化的骨髓间充质干细胞的免疫原性

目的:骨髓间充质干细胞(mesenchymal stemcells,MSC)具有多向分化潜能,又因其低免疫原性,成为细胞移植治疗的良好选择。本实验室前期实验表明猪MSC具有低免疫原性和免疫调节作用,而猪MSC在人体内微环境中,将自动分化。本试验研究猪MSC在体外诱导分化后是否还能维持其低免疫原性,仍具有免疫调节作用。方法:MSC细胞从近交系版纳微型猪骨髓中分离获得,转入SV40基因,进行永生化。再用β-甘油磷酸钠、地塞米松、抗坏血酸磷酸盐等体外诱导其分化为成骨细胞,以未分化MSC为对照,用RT-PCR法检测分化MSC的主要组织相容性抗原(swine lymphocyte antigen classⅠ、classⅡ,SLAⅠ、SLAⅡ)的表达情况,用单向混合淋巴细胞反应(MLR)的方法检测分化MSC是否仍不能引起人外周血淋巴细胞(human peripheral blood lymphocyte,hPBL)的增殖反应。结果:RT-PCR结果显示未分化MSC只有SLAⅠ表达;分化MSC既有SLAⅠ,也有SLAⅡ的表达,但很低。这一结果支持MSC的低免疫原性特性。混培结果也显示分化猪MSC与未分化猪MSC一样都不引...     

Titanium hydride and hydrogen concentration in acid‐etched commercially pure titanium and titanium alloy implants: a comparative analysis of five implant systems

Objectives: Acid etching is a popular method to texture the surface of dental implants. During etching, the titanium oxide protective layer is dissolved and small native hydrogen ions diffuse into the unprotected implant surface. They enrich the implant surface with hydrogen and precipitate into titanium hydride (TiH). The aim of this study was to measure the concentration of TiH at the implant surface and the total concentration of Hydrogen at five commercially available implant systems, made of either commercially pure (cp) titanium or titanium alloy. Material and methods: X‐Ray diffraction (XRD) was conducted on each implant system to determine the compounds present at the implant surface. Following a TiH₂/Ti calibration curve, the concentration of TiH was determined. Concentration of hydrogen in the implants was measured by the inert gas fusion thermal conductivity/infrared detection method. Results: XRD data showed that TiH was present on all cp titanium implants but not on the alloyed implants. TiH concentration varied between 5% and 37%. Hydrogen concentration varied between 43 and 108 ppm, no difference in uptake was found between the cp titanium and alloyed implants. Low solubility of hydrogen in α‐titanium is responsible for precipitation into TiH. Stronger etching conditions led to higher concentration of TiH2‐x. Conclusion: High solubility of hydrogen in the β‐phase of the alloy is preventing hydrogen from precipitating into TiH. All implants, even those lacking TiH at the surface, were enriched with hydrogen. In all implants, hydrogen concentration was within the normative limit of 130 ppm. To cite this article:
Szmukler‐Moncler S, Bischof M, Nedir R, Ermrich M. Titanium hydride and hydrogen concentration in acid‐etched commercially pure titanium and titanium alloy implants: a comparative analysis of five implant systems.
Clin. Oral Impl. Res. 21 , 2010; 944–950.
doi: 10.1111/j.1600‐0501.2009.01938.x     

二语产出性词汇习得中的石化现象分析

造成二语产出性词汇石化的原因有很多,缺乏学习动机,输入质量不高,缺乏积极的反馈,以及策略使用不当都可能导致产出性词汇的石化。针对不同原因,采取不同的解决办法,能有效防止产出性词汇石化现象的发生。     

Semantic dementia associated with amyotrophic lateral sclerosis

The association semantic dementia-amyotrophic lateral sclerosis has been rarely reported in the literature. We report a case study of a patient with a severe prosopagnosia in relation with semantic dementia associated, 12 months later, with a motor neuron disease.