Development of a syncytia inhibition assay for the detection of antibodies to bovine leukemia virus in naturally infected cattle; comparison with Western blot and agar gel immunodiffusion

A syncytia inhibition assay (SIA) for the detection of antibodies to bovine leukemia virus is described. This test involves specific antibody-mediated inhibition of BLV-induced cytopathic effects in an indicator cell line. A total of 300 sera were screened commercially by agar gel immunodiffusion (AGID) and were then screened by Western blot and SIA. The new assay system provided results which were comparable to Western blot and AGID. The results obtained suggest that SIA may be more sensitive than either of the other two assay systems examined for the determination of the infection status of cattle.     

皮肤角朊细胞与表皮干细胞双向电泳图谱的建立及差异分析

目的 建立皮肤角朊细胞与表皮干细胞的双向电泳图谱,并分析二者表达蛋白质的差异,为进一步研究体外调控表皮十细胞的增殖、分化提供线索.方法酶消化法获取单个表皮细胞悬液.Ⅳ型胶原快速贴壁法分选表皮干细胞.利用舣向电泳技术(2-DE)建立两种细胞的蛋白质表达图谱,并用Imagemaster 2D elite 5.0软件分析两种细胞的差异表达蛋一点.结果两种细胞的2-DE蛋白表达谱具有良好的重复性和可比性.皮肤角朊细胞与表皮干细胞的电泳图谱平均蛋白质点数分别为(982 ±18)个和(930 ±15)个,匹配点数为(850±13)个和(798±11)个,匹配率是86.56%和85.81%;两种细胞蛋白质间匹配点数是(886 ±8)个,匹配率是76.98%.找到差异蛋白点11个,其中只在表皮下细胞中表达或高表达的有8个;只在皮肤角朊细胞中表达或高表达的有3个.结论利用双向电泳法得到了分辨率较高儿重复性好的皮肤角朊细胞与表皮干细胞蛋白质组图谱,且二者存在有一定的差异.     

Identification, isolation, and characterization of a species-specific 30-kDa antigen of Oesophagostomum dentatum

In the search for a serology tool for the diagnosis of nonpatent as well as patent infections with Oesophagostomum dentatum in pigs a water-soluble, unglycosilated antigen of about 30 kDa specific for the third-stage larvae of the parasite was purified by ion-exchange chromatography. In Western blots, the antigen was first detected by antibodies at day 7 postinfection. Cross-reactivity with O. quadrispinulatum, Ascaris suum, or Trichuris suis was not detected. It is suggested that this protein is a suitable tool for the species-specific serodiagnosis of O. dentatum infection in pigs. Received: 15 June 1998 / Accepted: 28 September 1998     

Use of pulsed field gel electrophoresis to determine the source of microbial contamination of central venous catheters

Microorganisms detected in situ on the distal tip of central venous catheters (CVC) within 90 min of insertion were investigated using pulsed-field gel electrophoresis to analyse genomic fragments obtained with theSmaI restriction enzyme. Thirty patients received a triple lumen CVC, which was inserted directly through the skin using the Seldinger technique. In a further 30 patients a triple lumen CVC was inserted through a Swan sheath, thereby avoiding direct contact of the CVC with the skin. Staphylococci were isolated from the distal tips of the catheters in 6 patients (5 who had the CVC inserted directly through the skin and 1 who had the CVC inserted via a Swan sheath.) Twenty-three staphylococcal isolates were also isolated from the insertion equipment and the skin swabs surrounding the insertion site of these six patients. All the isolates were genotyped. In one of the patients the organisms isolated from the skin were identical to those on the CVC tip. In two further patients similar organisms were isolated from the insertion equipment and the patients' skin. These results, in addition to the reduced colonisation rates observed when catheters were introduced through a Swan sheath, support the hypothesis that microorganisms from the skin are impacted onto the CVC tip and the CVC insertion equipment at catheter insertion.     

Guinea-pig peritoneal macrophage receptor for IgG--II. Purification of the receptor and its partial characterization

The Fc gamma receptor of guinea-pig peritoneal macrophages was purified by affinity chromatography by using rabbit IgG or guinea-pig IgG2 coupled to Sepharose. Lysates prepared by treatment of 125I-labeled macrophages with NP-40 were first applied to BSA-Sepharose and then to IgG-Sepharose and eluted with 0.5 M acetic acid containing 1% NP-40. The specific binding was determined by interaction of the 125I-labeled receptor with IgG-Sepharose in the presence and absence of soluble IgG. The specific binding of the purified receptor was 42-82%. Interactions of the purified receptor with IgG-Sepharose were equally well inhibited by soluble rabbit IgG or guinea-pig IgG2, but not by F(ab')2 fragments. Inclusion of NP-40 in the buffer used in the assay reduced nonspecific binding of the receptor to the affinity gels. The purified receptor can be stored for 20 days at 4 degrees C without a significant loss of the specific binding activity. Analysis of the receptor by SDS-polyacrylamide gel electrophoresis, under nonreducing and reducing conditions, revealed two major peaks of radioactivity corresponding to mol. wts of about 50,000 and 25,000, and one very minor peak corresponding to a mol. wt of about 30,000. The results obtained suggest that the protein of the second major peak is a product of the dissociation of the protein of the first major peak rather than a product of its reduction by 2-mercaptoethanol.     

隔膜条件下骨再生成骨细胞来源的实验观察

目的:研究在隔膜条件下引导性骨再生过程中成骨细胞的来源,进一步认识引导性骨再生的机制.方法:以成年新西兰兔为研究对象,在双侧挠骨中段制作标准骨缺损不愈合模型,用硅胶膜成管状包裹一侧骨缺损,另一侧无特殊处理为对照.术后分别进行X线检查、常规HE染色以及SP方法BMP、BGP抗体的免疫组化染色.结果:硅胶膜在骨缺损处形成隔离密闭的腔室,将周围组织阻挡于骨缺损之外.早期骨端骨内膜、骨髓基质细胞大量增殖,形成肉芽组织占据骨缺损.骨再生过程中表现出明显的组织学特征:骨痂表面为2～3层成骨细胞,骨缺损中央为肉芽组织,两者之间为数层细胞形成的移行区,细胞排列疏松.早期骨端骨内膜、骨髓基质细胞BMP、BGP呈强阳性染色,骨痂生长过程中,移行区部分细胞呈阳性染色.结论:结果表明在隔膜条件下骨再生的成骨细胞在早期来源于髓内的骨内膜和骨髓基质细胞,骨痂形成后,成骨细胞则来源于骨内膜、骨髓、骨膜增殖细胞共同形成的肉芽组织中的间质细胞或成纤维细胞.     

两种兔源内毒素结合蛋白的分离、纯化及其体外生物学活性的对比研究

目的　从烧伤合并内毒素血症致多器官损害家兔血清中分离纯化内毒素结合蛋白 ,并初步对比研究它们的生物学活性。方法　兔血清蛋白质通过二步离子交换层析 (Bio Rex 70Resin、Mono Q)及凝胶过滤分离纯化 ,并经流式细胞分析实验、绵羊红细胞凝聚实验、氨基末端氨基酸残基测序等方法鉴定 ,再将所获蛋白质作用于体外培养的人单核细胞 (U937) ,观测其分泌TNFα等细胞因子的生物效应。结果　获得两种具有促进内毒素 (LPS)与外周血单核细胞 (PBMC)结合的蛋白质 ,其中一种相对分子质量为 6 0× 10 4 ,其N端 10个氨基酸序列为TNPGLITRIT ,证实为兔内毒素结合蛋白 (LBP) ;另一种蛋白质相对分子质量为 4 8× 10 4 ,其N端 10个氨基酸序列为GSQGTFTSEE ,与NCBI蛋白质库中的氨基酸序列进行比较 ,未发现相同序列 ,命名为p48。结论　p48与LBP具有相似的生物学功能 ,p48的生物学活性稍弱于LBP。提示体内除LBP外 ,p48也同样起着介导LPS的毒性作用。这可能是近年国外研究中阻断LBP的活性后 ,机体毒性反应并无明显减轻的原因之一。     

硅凝胶人工晶体的生物相容性

本文参照国内外有关医用高分子材料的生物学评价试验方法,对国产医用级硅凝胶人工晶体作了系统的生物学评价。结果表明:硅凝胶人工晶体对眼及皮肤无刺激作用、无热原、无毒性、体外溶血率小于5％,对细胞生长有促进作用,长期植入皮下时,随植入时间延长,囊壁厚度逐渐变薄,炎性细胞反应30天基本消失。染色体及骨髓多染红细胞未受影响。因此,可以认为硅凝胶人工晶体有良好的生物相容性。     

Identification of parasite proteins in a membrane preparation enriched for the surface membrane of erythrocytes infected with Plasmodium knowlesi

A subcellular fraction enriched in erythrocyte membranes has been isolated from rhesus monkey erythrocytes infected with Plasmodium knowlesi. Infected cells were lysed by centrifugation through a zone of hypotonic buffer and membranes isolated by equilibrium density gradient centrifugation in the same tube. The purified membrane fraction was shown to include the erythrocyte surface membrane by several methods: electron microscopy, identification of Coomassie Blue stained erythrocyte membrane proteins, identification of band 3 with a monoclonal antibody, and identification of radioiodinated cell surface proteins. The resulting ghosts were shown to be specifically reactive with monkey sera against the variant surface antigens of P. knowlesi by indirect immunofluorescence and membrane agglutination. No reactivity was seen with a monoclonal antibody (13C11) against the intracellular schizont surface. A number of metabolically labelled parasite proteins were enriched in this membrane function, including peptides of 277, 208, 173, 153, 134, 109, 80, 60 and 48 kDa and the variant surface antigens of variable molecular mass (180-207 kDa). These proteins were distinct from the major parasite proteins of total infected erythrocytes and isolated merozoites. The major glucosamine labelled glycoprotein of the internal schizont (230 kDa) was not found in this fraction. Moreover, no fragment of this parasite glycoprotein was found in this membrane fraction, indicating that no part of this molecule is transported to the erythrocyte surface. In contrast, the variant antigen of P. knowlesi, known to be on the erythrocyte surface, could be readily identified as peptides unique to specific cloned parasite lines. We propose that the other nine parasite proteins found within this membrane fraction represent a starting point for the identification of other parasite proteins transported to the surface membrane of the infected erythrocyte.     

Silicone rubber and natural rubber as biomaterials

The roles of silicone rubber and natural rubber as biomaterials are contrasted, with silicone rubber being widely used and natural rubber having, as yet, found limited application. Relevant properties of both elastomers are described, applications are discussed and possible future developments are considered.