Vitronectin-mediated inhibition of complement: evidence for different binding sites for C5b-7 and C9.

In the activated complement system, vitronectin (complement S-protein) occupies the metastable membrane binding site of the nascent precursor complex C5b-7, so that the newly formed SC5b-7 is unable to insert into cell membranes. Some evidence also indicates that vitronectin limits on-going membrane-associated pore formation by inhibiting C9 polymerization. It has been assumed that these two stages of terminal complement complex (TCC) inhibition take place through charge interactions between the heparin-binding region of vitronectin and homologous cysteine-rich sequences of the late complement proteins C6, C7, C8 and C9. We examined SC5b-7 formation and inhibition of C9 binding in the TCC using separate haemolytic assays. The mode of action of vitronectin in these assays was compared with two 15mer peptides which span residues 348-379 of the heparin-binding region, and a heparin-affinity polypeptide, protamine sulphate. The results showed that vitronectin acts predominantly through SC5b-7 production with a lesser effect on the inhibition of C9 lytic pore formation. In contrast, protamine sulphate did not prevent C5b-7 membrane attachment, but was a potent inhibitor of C9-mediated lysis. The peptides did not inhibit C5b-7 membrane insertion and only one affected C9 binding. These data suggest that the two stages of TCC inhibition involve separate binding sites on the vitronectin molecule. The site for association with nascent C5b-7 is unknown, whereas inhibition of C9 binding and pore formation takes place through the heparin-binding region.     

因特网上医学影像学资源获取技术

目的探讨医学网络资源的一般获取技巧,以及医学影像学资源的获取途径。方法应用因特网等关键词,采用医学专业检索引擎Medical Matrix,并在此基础上链接其他医学检索引擎,获得有关医学影像学文献的网址和相关网页。结果网上有一些专门的医学影像学资源网站,在高等医学院校和医学科研机构中经常包含医学影像学的资源。结论本文具体阐述了医学影像学资源的获取途径和技巧。     

N-Glycosylation contributes to the limited cross-reactivity between hemagglutinin neuraminidase proteins of human parainfluenza virus type 4A and 4B

cDNAs encoding human parainfluenza virus type 4B (hPIV-4B) hemagglutinin neuraminidase (HN) protein were cloned and the nucleotide sequences were determined. A high degree of identity (81.4%) was observed between the nucleotide sequences of hPIV-4A and -4B HN proteins, and an 87.3% identity was found between the deduced amino acid sequences. This degree of identity is considered to be greater than immunological similarity between hPIV-4A and -4B HN proteins determined using monoclonal antibodies. To elucidate the causes of the antigenic difference between HN proteins of hPIV-4A and -4B, we constructed three cDNAs of hPIV-4B HN whose potential N-glycosylation sites were partially or completely the same as in hPIV-4A HN cDNA. We compared the antigenicity of the expressed wild-type and mutant proteins, and found that the antigenicities of the mutant hPIV-4B HN proteins were more similar to the hPIV-4A HN protein than to the non-mutant hPIV-4B HN protein. This study indicated that the antigenic diversity between hPIV-4A and -4B was partly caused by deletion or creation of glycosylation sites, showing that the point mutations resulting in deletion or creation of glycosylation sites is one of the initial steps leading to the division of virus into subtypes. Received: 21 January 2000     

Diagnosis of squamous-cell carcinoma of the lung by sputum cytology: with special reference to correlation of diagnostic accuracy with size and proximal extent of resected tumor

Sputum cytology was performed in 179 cases of squamous-cell carcinoma of the lung; 134 cases were diagnosed as positive. There were no significant differences in diagnostic accuracy of sputum cytology between tumors sizes. In cases with tumors extending proximally into the main, lobar, or segmental bronchi, the diagnostic accuracy of sputum cytology was significantly higher than in cases where the proximal invasion of tumor was limited to the peripheral bronchi. In cases with tumors 3 cm or less in diameter, when tumors extended proximally into main, lobar, or segmental bronchi, the diagnostic accuracy of sputum cytology was significantly higher than in cases with tumors extending proximally into subsegmental or subsubsegmental bronchi. In peripherally located squamous-cell carcinoma, in cases in which the tumor arose in subsegmental or subsubsegmental bronchi, carcinoma could be detected by sputum cytology even when it was roentgenographically occult.     

Placental site trophoblastic tumor of the mediastinum

Choriocarcinoma has been described as the most frequent subtype of mediastinal germ cell tumors showing trophoblastic differentiation. We report a unique case of a placental site trophoblastic tumor, which developed in the mediastinum of a 14-year-old boy 2 years after the resection of a mature teratoma. The recurrent tumor was composed of a grossly hemorrhagic and necrotic mass. Histologically, diffusely infiltrating large polygonal cells with focal nodular growth and a teratomatous part containing mature intestinal, respiratory, and squamous epithelium with adjacent cutaneous adnexal structures were found. The typical morphologic features included vessel wall infiltration by the neoplastic cells with fibrinoid deposits and geographic necroses within the tumor masses. Characteristic diffuse positivity for melanoma cell adhesion molecule and human leucocyte antigen G was found on immunohistochemical investigation, confirming the diagnosis of placental site trophoblastic tumor. The patient died 1 year later after polychemotherapy. The outcome of this rare tumor is similar to the reported poor clinical outcome in patients with mediastinal choriocarcinomas.     

人era的结构特点分析及其定点突变体的构建

目的：构建最近克隆的人era基因的定点突变体。方法：利用数据库对era的结构特点进行分析，在此基础上用改良的重叠延伸法分别构建人EraN端和C端的定点突变体。结果：获得了分别针对人EraN端TGP结合结构域（位于29－36氨基酸残基）和C端具有RNA结合活性的 KH结构域（位于297－340氨基酸残基）的定点突变体。结论:人era定点突变体的构建为进一步的功能研究奠定了基础。     

Propene Polymerisation with rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2 as a Highly Active Catalyst: Influence of Monomer Concentration,Polymerisation Temperature and a Heterogenising Support

Propene was polymerised at high temperatures (up to 90 °C) using rac‐[Me₂Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)₂]ZrCl₂/MAO as the catalytic system. The increasing deactivation reaction rate of the catalyst for polymerisations above 60 °C was less for a silica supported catalyst compared with the homogeneous one. The isotacticity of polypropene decreases from 99 to 96%. Also the morphology changes with different temperatures.

Increasing of the thermal stability for the rac‐[Me₂Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)₂]ZrCl₂/MAO/SiO₂ with respect of the rac‐[Me₂Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)₂]ZrCl₂/MAO system.     

成年手术患者手术部位多重耐药菌感染及影响因素分析

目的 探讨手术部位多重耐药（MDRO）菌感染情况及危险因素,为手术部位感染的预防和治疗提供循证参考。方法 以2019—2020年焦作市某医院行手术治疗的成年患者作为研究对象,收集基本情况、疾病患者情况,从医院病历信息系统中调取患者手术及术前相关检测指标、用药情况等内容,对出现发热、切口红肿、引流液异常等疑似感染症状体征患者采集感染部位生物样本用于病原学培养及检测。采用描述流行病学分析方法对MDRO菌感染情况进行分析,并采用单、多因素分析方法对MDRO菌感染影响因素进行分析。结果 7 820例进行手术治疗患者共发生MDRO菌感染250例,感染率为3.20%,其中金黄色葡萄球菌感染6例,鲍曼不动杆菌感染14例,铜绿假单胞菌感染29例,肺炎克雷伯菌感染34例,大肠埃希菌感染167例。多因素Logistic回归分析显示,糖尿病（OR=3.578）、肿瘤（OR=4.135）、贫血（OR=4.701）、入住ICU（OR=5.045）、脏器穿孔（OR=2.414）、切口分类为Ⅱ或Ⅲ类（OR=2.284、3.013）、手术有风险（OR=5.135）、抗菌药物应用≥2种（OR=2.340）、抗菌药物疗程≥5 d（OR=4.759）、再手术（OR=2.036）是成年手术患者发生MDRO菌感染的危险因素。结论 成年手术患者手术部位MDRO菌感染较为常见,相关危险因素较多,临床可根据以上因素加强围手术管理,减少MDRO菌感染的发生。