Variable MHC class I engagement by Ly49 natural killer cell receptors demonstrated by the crystal structure of Ly49C bound to H-2K(b)

The Ly49 family of natural killer (NK) receptors regulates NK cell function by sensing major histocompatibility complex (MHC) class I. Ly49 receptors show complex patterns of MHC class I cross-reactivity and, in certain cases, peptide selectivity. To investigate whether specificity differences result from topological differences in MHC class I engagement, we determined the structure of the peptide-selective receptor Ly49C in complex with H-2K(b). The Ly49C homodimer binds two MHC class I molecules in symmetrical way, a mode distinct from that of Ly49A, which binds MHC class I asymmetrically. Ly49C does not directly contact the MHC-bound peptide. In addition, MHC crosslinking by Ly49C was demonstrated in solution. We propose a dynamic model for Ly49-MHC class I interactions involving conformational changes in the receptor, whereby variations in Ly49 dimerization mediate different MHC-binding modes.     

根据WHO新分类对493例非霍奇金淋巴瘤的临床病理分析

目的探讨非霍奇金淋巴瘤(NHL)的临床病理特点,评价世界卫生组织(WHO)2001淋巴瘤新分类标准的实用性.方法复查1992-2003年500例既往经病理诊断为NHL的病例,观察其形态学、免疫学及临床特点,按WHO新分类标准进行重新定性和分类,对其中156例有随访的病例进行生存率分析.结果 500例中,493例NHL,其中B细胞肿瘤69.0%,T和NK细胞肿瘤29.8%;前六位最常见类型为弥漫大B细胞淋巴瘤(DLBCL)、滤泡性淋巴瘤(FL)、非特殊型周围T细胞淋巴瘤(PT-un)、T淋巴母细胞淋巴瘤(T-LBL)、MALT型结外边缘区B细胞淋巴瘤(MALT)及B-小淋巴细胞性淋巴瘤(B-SLL);青少年中最常见为LBL、DLBCL及Burkitt淋巴瘤.在本组病例中,LBL在所有患者尤其是青少年患者中的比例均明显高于国外报道,FL的比例明显高于国内报道.不同类型NHL的生存情况在总体上差异有统计学意义(P<0.001),其中边缘区B细胞淋巴瘤(MZL)与SLL的预后最佳,LBL与PT-un的预后最差,DLBCL与FL介于前两组之间.按WHO推荐的两种方法划分的FL不同级别之间,生存情况差异无统计学意义(P>0.05).结论淋巴瘤WHO2001新分类实用性强、便于掌握,各亚型的形态学、免疫学指标可靠,结合临床能较好应用于淋巴瘤的诊断和预后.但是,建议国内同行对FL的判断及分级标准进一步审定.     

CDX2 expression is progressively decreased in human gastric intestinal metaplasia, dysplasia and cancer.

Intestinal metaplasia is a key event in multistep gastric carcinogenesis. CDX2, a master regulator of intestinal phenotype, was shown to play a tumor-suppressive role in colon cancer. However, it was reported to be expressed in nearly all gastric intestinal metaplasia and many gastric cancers. As CDX2 is differentially expressed in normal stomach and intestine, we sought to relate the CDX2 expression to gastrointestinal differentiation along gastric carcinogenesis. The expression of CDX2 protein in gastric intestinal metaplasia, dysplasia and cancer was examined and related to their gastrointestinal differentiation. CDX2 expression was significantly decreased in incomplete intestinal metaplasia, which expresses both gastric mucins (MUC5AC and MUC6) and intestinal mucin (MUC2), compared with complete intestinal metaplasia, which expresses intestinal mucin (MUC2) only. Although incomplete intestinal metaplasia morphologically resembles colon, its CDX2 expression was apparently lower than that in the normal colon. Moreover, CDX2 expression was progressively reduced in gastric dysplasia and cancer. The CDX2 expression in gastric cancer was also inversely correlated with the expression of gastric mucins. As incomplete intestinal metaplasia is associated with higher risk of gastric cancer, its lower CDX2 expression compared with that in complete intestinal metaplasia and normal colon epithelium resolved the current contradiction between the tumor-suppressive role of CDX2 in the colon and the high prevalence of CDX2 in intestinal metaplasia. Further decrease of CDX2 expression in gastric dysplasia and cancer suggests that CDX2 plays a similar anticarcinogenic role in intestinal metaplasia as it does in colon. Intestinal metaplasia or dysplasia with low expression of CDX2 may serve as predictive markers for gastric cancer.     

Arthrobacter scleromae sp. nov. isolated from human clinical specimens

A gram-positive, coryneform bacterium was isolated from swollen scleromata of a dermatosis patient. An analysis of its phenotypic, chemotaxonomic, and genotypic characteristics showed that this bacterium is closely associated with Arthrobacter oxydans and Arthrobacter polychromogenes but that it belongs to a distinct species, for which the name Arthrobacter scleromae sp. nov. is proposed.     

Correlation of AIB1 overexpression with advanced clinical stage of human colorectal carcinoma

AIB1, a member of the steroid receptor coactivator 1 family, has been cloned on 20q12 and is a candidate oncogene in human breast cancer. It is commonly amplified and overexpressed in several types of human cancers. In this study, we examined the expression of AIB1, as related to clinicopathologic features, in 85 human colorectal cancers (CRCs). The status of the number of AIB1 copies, p53 expression, and DNA ploidy was also analyzed. The overexpression of AIB1 was detected in 35% of CRCs. Amplification of AIB1 was observed in 10% of CRCs. In addition, the overexpression of AIB1 was observed more frequently in CRCs in later clinical stages (T3 N1 M0/T3 N0 2M1), compared with that in T3 N0 M0 stage (P < .05). These results suggest that overexpression of AIB1 might provide a selective advantage for the developmental growth and/or progression of subsets of CRCs. In addition, a significant correlation (P < .05) of overexpression of AIB1 with p53 overexpression as well as with aneuploid DNA content was observed in these CRCs. The overexpression of p53 was also correlated significantly with CRC DNA ploidy (P < .05). Furthermore, there was a substantial population of CRCs showing overexpression of both AIB1 and p53 protein and all had aneuploid DNA content; most of these were in the later clinical stage. These findings suggest a possible convergence of AIB1 with a pathway involving p53, which might induce chromosomal instability and affect the clinical phenotype of a subset of CRCs.     

抑郁障碍患者与家属家庭亲密度适应性和情绪状况的研究

目的探讨抑郁障碍患者与家属的家庭亲密度适应性和情绪状况,为抑郁障碍患者的健康教育及家庭干预提供科学有效的理论依据。方法选择2006年6～9月在北京大学第六医院就诊的抑郁障碍患者95例及共同陪伴的直系家属95例为调查对象。采用家庭亲密度和适应性量表中文版(FACES-CV)、Zung氏焦虑自评量表和Zung氏抑郁自评量表。结果1患者的家庭亲密度得分与国内常模一致(P>0.05),但适应性得分低于国内常模(P<0.01);焦虑、抑郁得分高于国内常模(P<0.01)。家属的家庭亲密度得分高于国内常模(P<0.01),适应性得分低于国内常模(P<0.01)。家属的焦虑得分与国内常模一致(P>0.05),但抑郁得分高于国内常模(P<0.05)。2家庭模式分型构成比:中间型47.9%,平衡性26.3%,极端型25.8%。患者的家庭"拱极模式"以"僵硬—松散型"居多,家属则以"自由—缠结型"居多。3家庭亲密度与患者的家属的文程化度有关,相关系数范围(r=0.21～0.26,P<0.05)、与家庭人数呈负相关(r=-0.21,P<0.01);与患者及家属的焦虑、抑郁情绪呈显著负相关,相关系数范围(r=-0.30～0.37,P<0.01);家庭适应性与患者的年龄(r=0.28,P<0.01)、文化程度(r=0.34,P<0.01)有关。与家属的年龄(r=0.26,P<0.05)文化程度(r=0.22,P<0.05)有关。与患者和家属的焦虑、抑郁情绪呈显著负相关,相关系数范围(r=-0.30～-0.42,P<0.01)。结论家庭亲密度适应性与患者和家属的文化程度、焦虑、抑郁情绪有关,家庭亲密度与患者的家庭人数有关,家庭适应性与患者和家属的年龄有关。     

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.     

在中国发现普马拉型汉坦病毒

目的：确定我国是否存在普马拉（Puumala)病毒。方法：从我国东北地区棕背Bing肺标本中用RT－PCR扩增汉坦病毒S片段基因序列，对所扩增序列进行核苷酸序列测定和分析。结果：从我国东北地区棕背Bing肺标本中扩增出长度为926碱基对的cDNA片段，核苷酸序列测定证实为普马拉病毒S片段序列。与不同型别汉坦病毒代表株进行比较表明，此次发现为新的普马拉病毒株，系统发生分析结果表明，此次发现的病毒与普马拉病毒P360、K27、CG－820、CG－17株种系相近，同源性达到99％以上。结论：我国存在普马拉病毒，我国新发现的普马拉病毒核苷酸序列和俄罗斯远东地区普马拉病毒接近。     

膝关节动脉血液供应的初步观察

本文选择固定和新鲜尸体下肢标本57侧,采用局部解剖、动脉铸型、动脉造影和标本透明等方法,对膝关节动脉血液供应作了初步观察。动脉关节支起点变异和共干形式,以右侧居多。膝区各动脉均有特殊的形态和一定的分布区域,在每一局部几个血液供应来源中,总有一个主次关系和层次关系。膝区动脉按口径大小,可以分成3组。口径的变化除了可以评价局部血液供应丰富的程度外,也是衡量相邻动脉大小的指征。整个膝区动脉血液供应配布比较均匀对称。供应膝关节的各动脉起点的高度是恒定的,相互间保持一定关系。本文还就纯关节支和肌关节支的概念、动脉吻合、局部“乏血管区”、髌前动脉网与髌骨血液供应的关系等进行了简单讨论。