The T cell antigen receptor α and β chains interact via distinct regions with CD3 chains

Selective pairwise interactions between CD3 chains and the clonotypic T cell antigen receptor (TCR)-α, -β chains has recently been established. In this study, the region of interaction between clonotypic and CD3 chains involved with assembly was examined. To determine the site of protein interaction a variety of genetically altered TCR chains were constructed. These included: truncated proteins, lacking transmembrane and or cytosolic domains; chimeric proteins, in which extracellular, transmembrane or cytosolic domains were replaced with similar domains derived from either the Tac antigen or CD4; and point mutagenized TCR chains. COS-1 cells were transfected with cDNA, metabolically labeled, and immunoprecipitates analyzed using non-equilibrium pH gel electrophoresis (NEPHGE)-SDS/PAGE. The results demonstrated that assembly between TCR-α and TCR-β chains occurred at the extracellular level. Assembly of the TCR-α chain with CD3-δ, and CD3-ε was localized to an eight-amino acid motif within the transmembrane domain of TCR-α. Site-specific mutations of the TCR-α charged residues within this motif ( arginine, lysine) to leucine and similar point mutations of the transmembrane CD3-ε and CD3-δ charge groups resulted in the abrogation of assembly. In contast, TCR-β and CD3-ε binary complexes interacted via their extracellular domain. Analogous to TCR-α, the site of TCR-β and CD3-δ assembly was at the transmembrane region. Despite multiple genetic manipulations on CD3-γ and ζ; these proteins failed to assemble with TCR-α. Similarly, there was no interaction between TCR-β and ζ. These findings when coupled with the information on pairwise interactions and formation of higher order subcomplexes extend our model for the structure of the TCR complex.     

Responses against complex antigens in various models of CD4 T-cell deficiency

The most common models of CD4 T-cell deficiency are mice exogenously injected with anti-CD4 antibody (Ab), CD4 knockout (CD4^−/−) and major histocompatibility complex (MHC) class II knockout (class II^−/−) mice. We recently described the anti-CD4 Ab transgenic mouse (GK) as an improved CD4 cell-deficient model. This review compares this new GK mouse model with the widely available class II^−/− and CD4^−/− mice, when exposed to complex antigens (foreign grafts and during bacterial or viral infection). We highlight here the cytometric and functional differences (including Ab isotype, viral or bacterial clearance, and graft survival) among these CD4 cell-deficient models. For example, whereas grafts are generally rejected in class II^−/− and CD4^−/− mice as quickly as in wild-type mice, they survive longer in GK mice. Also, CD4^−/− mice produce IgG against both simple model and complex antigens, but class II^−/− and GK mice produce small amounts of IgG2a against complex antigens but not simple model antigens. These differences harbinger the caveats in the use of these various mice.     

Differential expression of p53 gene family members p63 and p73 in head and neck squamous tumorigenesis

p73 and p63 are recently cloned genes that share considerable structural and functional homologies with the p53 tumor suppressor gene. These genes, unlike p53, express multiple mRNA isoforms with variable biologic functions, and their suppressor nature has yet to be confirmed. To determine the interrelationship between these genes in the tumorigenesis of head and neck squamous carcinoma (HNSC), we performed immunohistochemical analyses of their protein products and compared the data with clinicopathologic parameters in 38 patients. In histologically normal epithelium, p53 and p73 showed similar basal and/or parabasal expression, but that of p53 was weaker and discontinuous. p63 staining was noted in more suprabasal cellular layers and was stronger. In dysplasias, all three markers manifested variable but gradual increase in extent and intensity of cellular expression with histologic progression. In carcinomas, p63 was the most frequently expressed (94.7%), followed by p73 (68.4%) and p53 (52.6%). Significant statistical correlation was noted only between p63 and p73 expressions (P =.04). Although no statistical correlation was found between p53 and p63 or p73, p53-negative tumors overexpressed either p63 or p73. p73 expression was associated with distant metastasis and perineural/vascular invasion. Our study indicates that (1) p63 and p73 expression may represent an early event in HNSC tumorigenesis, (2) the lack of correlation between p73 or p63 and p53 expression suggests an independent and/or compensatory functional role, (3) p73 expression may play a part in HNSC progression, and (4) p73 and p63 may function as oncogenes in the development of these tumors.     

先兆子痫患者HLA-DQA1、-DQB1、-DPA1基因多态性

目的:探讨人类白细胞抗原HLA-DQ-A1、DQB1、DPA1基因多态性与先兆子痫发病的关系。方法:采用序列特异性引物技术(PCRSSP)对46例先兆子痫患者和105例正常孕妇及其新生儿进行HLA-DQ-DPA1等位基因分型。结果:所有标本共检出11种HLADQA1基因表型、16种HLADQB1基因表型、6种HLADPA1基因表型。先兆子痫患者HLA-DQ-B10301基因频率高于正常孕妇,差异有显著性(Pc=0.032,RR=2.43,AR=0.30),其余各基因表型频率两组比较差异均无显著性。结论:HLADQB10301基因可能是一种先兆子痫发病的易感基因。     

Ad5F35-LMP2重组腺病毒免疫效果的研究

目的了解含有EB病毒潜伏膜蛋白2的非复制型重组腺病毒(Ad5F35-LMP2),免疫恒河猴的特异性细胞和体液免疫的效果。方法分别使用高剂量(1.5×1010TCID50/只)、中剂量(1.5×109TCID50/只)、低剂量(1.5×108TCID50/只)Ad5F35-LMP2重组腺病毒,同时设对照组(PBS4.0ml/只)。肌内注射免疫恒河猴,每个月一次,共免疫3次,第0、4、8、12周时使用Elispot方法检测猴外周血EBV-LMP2细胞毒性T细胞应答,同时应用免疫酶方法检测血清中LMP2抗体。结果3个剂量Ad5F35-LMP2腺病毒免疫恒河猴均可以诱导出有效的细胞免疫应答及一定的抗体应答,免疫应答水平的高低与病毒剂量的高低有一定的关系,较高剂量产生的细胞及体液免疫应答水平比低剂量的高。结论Ad5F35-LMP2非复制型重组腺病毒疫苗可以有效的诱导恒河猴产生EBV-LMP2特异性细胞和体液免疫反应。     

Recurrent genetic alterations in 26 colorectal carcinomas and 21 adenomas from Chinese patients

Colorectal cancer (CRC) is one of the most common malignancies worldwide. The incidence of CRC in the Chinese population has increased dramatically during the last two decades; however, nonrandom chromosomal alterations in Chinese patients have not been described. In the present study, comparative genomic hybridization (CGH) was applied to detect recurrent chromosome alterations in 26 primary colorectal carcinomas and 21 colorectal adenomas from Chinese patients. In CRC, several recurrent chromosomal changes were found, including gains of 8q (14/26 cases, 54%), 20q (54%), 3q (50%), 13q (50%), 5p (46%), 7p (42%), 7q (42%), and 12p (38%) and losses of 18q (65%) and 17p (42%). From comparison with previous CGH studies, the frequent gains of 3q and 12p might be distinctive occurrences in Chinese patients. The distribution of frequently found chromosomal alterations in different locations was studied. The gain of 20q was more frequently found in colon cancer (P<0.01) and the gain of 12p was more frequently found in rectal cancer. Chromosomal alterations were found in 19/21 of adenomas; the most frequent chromosomal alteration was the loss of 18q (9/21 cases, 43%). These recurrent alterations provide several starting points for the isolation of candidate oncogenes and tumor suppressor genes.     

构建7q32区域鼻咽癌和正常鼻咽上皮细胞部分基因的表达图谱

目的构建７ｑ３２区域鼻咽癌细胞和组织及原代培养人正常鼻咽上皮细胞的部分基因表达图谱。方法通过差异ＲＴ－ＰＣＲ和Ｎｏｒｔｈｅｒｎ杂交的方法检测定位于７ｑ３２区域的２０个ＥＳＴ在鼻咽癌细胞和鼻咽癌组织及原代培养人正常鼻咽上皮细胞ｍＲＮＡ的表达水平。结果８个ＥＳＴ在鼻咽癌细胞ＨＮＥ１和原代培养人正常鼻咽上皮细胞中表达量较一致，７个ＥＳＴ在两种细胞中均无表达，３个ＥＳＴ（Ｗ７２６８８、Ｈ１９８３０、ＡＡ１３０６３０）在鼻咽癌细胞株中表达上调，而２个ＥＳＴ（ＡＡ０７０４３７、Ｈ９０８８２）在原代培养人鼻咽上皮细胞中表达上调。在１３例鼻咽癌活检组织中３０．７％（４／１３）的ＡＡ０７０４３７表达下调，７７％（１０／１３）的Ｗ７２６８８和７７％（１０／１３）的Ｈ１９８３０表达上升。结论构建了７ｑ３２区域鼻咽癌细胞和组织及原代培养人正常鼻咽上皮细胞部分基因表达图谱，并初步认为Ａ０７０４３７的表达下调和Ｗ７２６８８、Ｈ１９８３０的过表达与鼻咽癌的发生有关。     

维生素D3受体对hsp90β基因表达的调控作用

鉴于热休克蛋白９０β（ｈｓｐ９０β）基因内含子中含有维生素Ｄ３受体（ＶＤＲ）结合位点，为探讨作为核受体家族成员的ＶＤＲ是否对核受体特异分子伴侣的ｈｓｐ９０β基因的表达具有调控作用，我们开展了本项研究。分别将野生型ＶＤＲ、含Ｎ端（１～１３３氨基酸残基）及Ｃ端（２８１～４２７氨基酸残基）片段的ＶＤＲ突变体真核表达质粒与人ｈｓｐ９０β基因调控片段（－１０３９／＋１５３１）介导的氯霉素乙酰基转移酶（ＣＡＴ）报告基因质粒共转染Ｊｕｒｋａｔ细胞，检测正常及经热休克（４２℃，１ｈ）处理后细胞裂解液中ＣＡＴ活性。结果表明ＶＤＲＮ端增强、而Ｃ端抑制ｈｓｐ９０β的组成性表达；在热诱导条件下野生型ＶＤＲ对ｈｓｐ９０β的表达有一定的抑制作用，而其Ｃ端片段的抑制较强。为进一步研究ＶＤＲ对细胞内源性热休克基因表达的影响，我们用ＲＴＰＣＲ方法研究了ＶＤＲ的对细胞内ｈｓｐ９０β基因ｍＲＮＡ水平的影响，发现ＶＤＲ过表达对ｈｓｐ９０β的热诱导表达明显抑制。结果提示ＶＤＲ对ｈｓｐ９０β基因的组成性和热诱导表达的调控机制不同。     

内骨架一体化小腿假肢的生物力学研究

一体化假肢是以聚合物为材料从接受腔到假腿一体成型的新型下肢假肢，它比传统型假肢更经济、美观、轻便，具有较大的应用前景。目前的相关研究主要集中在设计与制作及少量的临床研究方面。由于一体化假肢与传统型假肢在结构上的差异，有必要对其进行应力分析。本研究的目的是开展内骨架一体化假肢的生物力学研究，本研究基于内骨架一体化小腿假肢的真实几何构型，建立三维有限元模型，计算该模型在模拟Heel OH步态时相的载荷作用下的应力分布；在保持该模型的几何形状不变的情况下，建立了三个不同壁面厚度的一体化小腿假肢的有限元模型，分析壁面厚度对一体化小腿假肢应力分布的影响；通过分别赋予模型四种不同高分子聚合物的材料力学特性值，分析不同材料的一体化假肢的应力分布特点；分别对模型施加与正常步态的五个典型时相对应的载荷，分析一体化小腿假肢在各步态时相的应力分布特点。本研究结果对一体化假肢设计有指导价值。     

保留部分上鼓室外侧壁鼓室成形术临床初探

目的 :探讨保留部分上鼓室外侧壁鼓室成形术的临床价值。方法 :对 4例慢性化脓性中耳炎患者行保留部分上鼓室外侧壁鼓室成形术的临床资料进行回顾性分析。结果 :经随访半年 ,听力提高 10～ 2 0dB ,鼓膜外形正常 ,全部干耳。结论 :保留部分上鼓室外侧壁鼓室成形术能有效提高听力和干耳率 ,且手术安全