白藜三醇对人低密度脂蛋白氧化修饰的影响

为探讨白藜三醇的抗脂质氧化作用及其可能机制，采用Ｃｕ＾２＋和２，２’－盐酸脒基丙烷两种不同的氧化体系诱导下沉人低密度脂蛋白的氧化反应，应用硫代巴比妥酸法测定低密度脂蛋白氧化过程中硫代巴比妥酸反应物质和氧化型低密度脂蛋白的相对电泳迁移率的变化。结果发现５０μｍｏｌ／Ｌ白藜三醇可使Ｃｕ＾２＋介导的低密度脂蛋白氧化反应明显减弱，其硫代巴比妥酸反应物质和相对电泳迁移率分别下降７０．５％和４２．３％（Ｐ〈０     

氧化型高密度脂蛋白研究进展

高密度脂蛋白发生氧化修饰后,抗原性发生了变化,不被高密度脂蛋白受体所识别;２３４ ｎｍ 光吸收、硫代巴比妥酸反应物质含量、脂氢过氧化物含量及电泳迁移率均增加。体外用 Ｃｕ２ ＋ 介导高密度脂蛋白发生氧化修饰,具有特殊的氧化动力学：在其氧化修饰过程中脂氢过氧化物、共轭二烯、硫代巴比妥酸反应物质及电泳迁移率均显示延滞期。     

巨噬细胞氧化修饰极低密度脂蛋白及Cu2+修饰的极低密度脂蛋白对单核细胞与内皮细胞粘附的影响

极低密度脂蛋白(VLDL)与小鼠腹腔巨噬细胞温育24小时和48小时后,其硫代巴比妥酸反应物质值明显高于无细胞对照组,琼脂糖电泳速度也加快,两者一致。结果说明小鼠腹腔巨噬细胞可以氧化修饰极低密度脂蛋白。VLDL在体外用Cu~(2+)修饰后。硫代巴比妥酸反应物质明显增加,琼脂糖凝股电泳速度加快。比较正常的VLDL(n—VLDL)及Cu~(2+)氧化的VLDL(Ox—VLDL)对内皮细胞粘附单核细胞的影响时,发现在所用各种浓度下,Ox—VLDL单核细胞的粘附率比n—VLDL组大得多(P<0.0001),说明VLDL被氧化后明显增加单核细胞与内皮细胞的粘附。     

培养的人动脉平滑肌细胞诱导高密度脂蛋白氧化修饰

目的　探讨高密度脂蛋白氧化修饰发生的机制。方法　利用体外培养的人动脉平滑肌细胞与人血浆高密度脂蛋白共同温育后 ,用琼脂糖凝胶电泳方法观察高密度脂蛋白电泳迁移率 ,紫外光分光光度法测定高密度脂蛋白共轭二烯的含量 ,利用荧光分光光度法测定其硫代巴比妥酸反应物质的量 ,用可见光分光光度法测定高密度脂蛋白的脂氢过氧化物含量。结果　人血浆高密度脂蛋白与人动脉平滑肌细胞共同培养 4 8h后 ,与天然高密度脂蛋白比较 ,其电泳迁移率明显增加 ,其共轭二烯、硫代巴比妥酸反应物质及脂氢过氧化物的含量均比天然高密度脂蛋白显著增加 (P <0 .0 1)。结论　体外培养人动脉平滑肌细胞能使高密度脂蛋白发生氧化修饰     

低密度脂蛋白体外氧化修饰过程中几种产物变化的动力学研究

用Ｃｕ＾２＋引发低密度脂蛋白的氧化修饰，研究了低密度脂蛋白氧化修饰过程中脂氢过氧化物，共轭二烯烃，硫代巴比妥酸反应物质琼脂糖凝胶电泳迁移率和荧光物质含量变化的动力学。     

巨噬细胞氧化修饰极低密度脂蛋白及Cu2+修饰的极低密度脂蛋白对单核细胞与内皮细胞粘附的影响

极低密度脂蛋白(VLDL)与小鼠腹腔巨噬细胞温育24小时和48小时后,其硫代巴比妥酸反应物质值明显高于无细胞对照组,琼脂糖电泳速度也加快,两者一致。结果说明小鼠腹腔巨噬细胞可以氧化修饰极低密度脂蛋白。VLDL在体外用Cu²⁺修饰后。硫代巴比妥酸反应物质明显增加,琼脂糖凝股电泳速度加快。比较正常的VLDL(n—VLDL)及Cu²⁺氧化的VLDL(Ox—VLDL)对内皮细胞粘附单核细胞的影响时,发现在所用各种浓度下,Ox—VLDL单核细胞的粘附率比n—VLDL组大得多(p<0.0001),说明VLDL被氧化后明显增加单核细胞与内皮细胞的粘附。     

内源性高甘油三酯血症患者血浆极低密度脂蛋白、低密度脂蛋白及高密度脂蛋白对血凝及纤维蛋白溶解的影响

研究内源性高甘油三酯血症患者血浆极低密度脂蛋白、低密度脂蛋白及高密度脂蛋白是否发生了氧化修饰及其对凝血及纤维蛋白溶解活性的影响。对 2 1例内源性高甘油三酯血症患者与 2 1例年龄性别相近的正常人的血脂、脂质过氧化物进行了分析。用一次性密度梯度超速离心法分离血浆极低密度脂蛋白、低密度脂蛋白及高密度脂蛋白。测定这 3种脂蛋白的 2 34nm吸光度、相对电泳迁移率和硫代巴比妥酸反应物质含量。分别将这 3种脂蛋白加入由正常人新鲜混合血浆构成的反应系统中 ,按试剂盒分别测定凝血酶原时间、活化部分凝血酶原时间、组织型纤溶酶原激活物活性及纤溶酶原激活物抑制剂 1活性。内源性高甘油三酯血症患者血浆甘油三酯含量平均升高 2 .73倍 ,高密度脂蛋白胆固醇下降 1.71倍 ,同时硫代巴比妥酸反应物质含量升高 1.2 2倍 ;内源性高甘油三酯血症组极低密度脂蛋白、低密度脂蛋白及高密度脂蛋白的 2 34nm吸光度、相对电泳迁移率和硫代巴比妥酸反应物质含量均较对照组显著增加 (P <0 .0 1) ,表明内源性高甘油三酯血症患者血浆极低密度脂蛋白、低密度脂蛋白及高密度脂蛋白均发生了氧化修饰 ,生成了氧化极低密度脂蛋白、氧化低密度脂蛋白及氧化高密度脂蛋白。凝血酶原时间及活化部分凝血酶原时间在分别加入内     

心脏手术中过氧化反应产物的增多:自由基形成之证据

作者测定择期冠状动脉旁路术中不同时刻肺隔置中性粒细胞(N)的程度,同时隔绝空气采血,按改良的硫代巴比妥酸反应测定过氧化反应产物(POP)的血浆浓度,作为氧化剂自由基(超氧化物阴离子、羟基和单电子键氧)活性的指标.术前未使用类固醇激素,注入鱼精蛋白前不输入血液或血液制品,中度降温下进行心肺转流,采用滚压泵和鼓泡式氧合     

一氧化氮在低密度脂蛋白氧化中的作用及调控研究

通过给小鼠腹腔注射云芝多糖，并用干扰素γ，脂多糖及佛波酯醇刺激细胞，观察细胞一氧化氮的产量，测定脂氢过氧化物和硫代巴比妥酸反应物质，以反应低密度脂蛋白的氧化程度，从而部分揭示巨噬细胞氧化低密度脂蛋白的机制，探讨一氧化氮在低密度脂蛋白氧化中的作用和云芝多糖的抑制效果。     

内源性高甘油三酯血症患者体内存在氧化型低密度脂蛋白、极低密度脂蛋白和高密度脂蛋白

为探讨内源性高甘油三酯血症患者体内低密度脂蛋白、极低密度脂蛋白及高密度脂蛋白是否发生氧化修饰，对25例内源性高甘油三酯血症患者与25例年龄性别相匹配的正常人的血糖、血脂、载脂蛋白及脂过氧化物进行了分析，并对其血浆低密度脂蛋白、极低密度脂蛋白及高密度脂蛋白的电泳迁移率、234nm光吸收和硫代巴比妥酸反应物质含量的改变进行了测定。结果表明，内源性高甘油三酯血症患者血浆甘油三酯、脂过氧化物和载脂蛋白B100、CⅢ、CⅢ及E显著升高（P＜0．01），高密度脂蛋白和载脂蛋白AⅠ显著降低（P＜0．01），低密度脂蛋白、极低密度脂蛋白和高密度脂蛋白电泳迁移率均较正常人相应脂蛋白的迁移率增加，234nm光吸收及硫代巴比妥酸反应物质含量均显著增加（P＜0．01）。说明内源性高甘油三酯血症患者不仅血浆低密度脂蛋白、而且极低密度脂蛋白和高密度脂蛋白均发生了氧化修饰。     

钩端螺旋体脂多糖化学组成的进一步分析

应用改良酚水法提取了问号状钩端螺旋体波摩那群波摩那型罗株的脂多糖。该脂多糖所含的主要单糖为木糖、半乳糖、核糖、甘露糖、鼠李糖和肌醇,主要脂肪酸为3-羟基15烷酸和3-羟基-棕榈酸。此外,尚检出少量3-羟基-月桂酸和3-羟基肉豆蔻酸。该脂多糖含有微量性质不明的2-酮-3-脱氧-辛酮糖酸,但其在纸层析上的迁移率与KDO标准品有明显差异。实验结果提示钩端螺旋体脂多糖不同于典型的细菌内毒素。     

钩端螺旋体内毒素的实验研究 Ⅰ.钩端螺旋体内毒素的生物学活性

钩端螺旋体波摩那群波摩那型56608株和赛玛伦群帕托克型帕托克Ⅰ株的酚水提取物具有较大肠杆菌内毒素为弱的生物学活性。该提取物使鱟血液变形细胞溶解物凝胶化,注入家兔后能使动物出现发热、血糖升高和Shwartzman现象,但较大剂量时方能致死小鼠。小鼠内脏病理检查结果表明,各脏器均出现DIC,尤以肺组织更为明显。     

钩端螺旋体脂多糖对小鼠感染伤寒沙门氏菌O_(901)的保护作用

钩端螺旋体(钩体)属革兰氏阴性菌,可是有无内毒素尚无定论。笔者曾发现,从黄疸出血群软型钩体提取的脂多糖,在化学结构上与大肠杆菌内毒素相似,并显示出革兰氏阴性菌内毒素的生物学活性,但它能否象革兰氏阴性杆菌那样提高机体非特异性抗感染力尚不清楚。本试验结果证实,它和大肠杆菌内毒素一样,能够显著提高小鼠感染伤寒沙门氏菌后的存活率,即提高机体的非特异性抗感染力。试验结果还表明,钩体脂多糖的提高机体非特异性抗感染作用受其剂量的影响,它的作用机制尚需进一步研究。     

钩端螺旋体脂多糖的结构和功能分析

钩端螺旋体脂多糖(L-LPS)是钩体外膜上的主要成分,由O-抗原特异性多糖、核心寡糖和脂质A 3部分组成。L-LPS是一种重要的毒力因子,在钩体致病性、免疫性及与外部环境的相互作用中扮演着重要的角色。基于LPS结构特征的不同钩体分为不同的血清型。钩端螺旋体的LPS结构研究对于钩体的分子分型及钩体糖-偶联疫苗的开发具有重要意义。本文对L-LPS的结构、O-抗基因簇、生物学活性和钩体病预防方面的研究进展进行简要的综述。     

钩端螺旋体脂多糖对小鼠成纤维细胞和豚鼠脏器组织的侵入及损害

应用免疫胶金技术证实钩端螺旋体脂多糖（Ｌ－ＬＰＳ）作用于体外培养的小鼠成纤维细胞后５ｍｉｎ即能侵入胞浆,３０ｍｉｎ后可在细胞核中检出Ｌ．一！Ｉ５。钩端螺旋体实验感染的豚鼠各内脏组织的细胞间隙、胞浆及核等内均存在１．一！,ＰＳ,尤以肾和肺脏检出阳性率较高。Ｌ－ＬＰＳ检测阳性的小鼠成纤维细胞和感染豚鼠内脏组织细胞均出现相似的超微结构病变,如内质网扩张、膜旁核糖体脱落、线粒体嵴或外膜消失等。实验结果表明Ｌ－ＬＰＳ是钩端螺旋体主要致病物质之一。     

脂质体作为钩端螺旋体抗原载体、佐剂的研究

自黄疸出血群赖型70091株钩体提取了红细胞致敏物(ESS)和脂多糖(L-LPS)两种抗原成分。将它们分别与脂质体组装,形成新的钩体免疫制剂。通过金地鼠的保护力试验和家兔的抗体反应的检测,研究两种抗原的免疫原性和脂质体的免疫增强作用。结果表明,DPPC:Chol:DCP 脂质体能显著增强ESS的免疫原性。单纯ESS在每只地鼠40μg剂量时,只获36.7％的存活率,而脂质体-ESS则达到96.6％,并且这一活性依赖于ESS与脂质体在结构上的组装。该制剂还能增强家兔的抗体反应。此外,经脂质体-ESS制剂保护的存活金地鼠作肾培养,未发现有钩体带菌者。在本实验条件下,无论用单纯的或与脂质体组装的钩体LPS,直接免疫金地鼠,均未获得良好的保护力;然而用L-LPS免疫的兔血清对金地鼠则有良好的被动保护作用。     

Mechanism of human platelet activation by endotoxic glycolipid-bearing mutant Re595 of Salmonella minnesota

The mechanism through which human blood platelets interact with gram- negative bacteria with well-defined structural variations in endotoxic lipopolysaccharide was studied. Secretion of 14C-serotonin and aggregation of platelets separated from plasma proteins were observed on challenge with rough mutant Re595 of Salmonella minnesota possessing a glycolipid outer layer composed of Lipid A and 2-keto-3-deoxyoctonate (KDO) but lacking heptose phosphate in the core and O-polysaccharide in its outer portion. Both 14C-serotonin secretion and platelet aggregation were concentration-dependent, with a half-maximum response at the ratio of one bacterial colony-forming unit (CFU) to two platelets. The aggregation of human platelets induced by mutant Re595 was divalent cation-dependent and required secretion of ADP and fibrinogen from platelet storage granules because it was inhibited by chelators, by the ADP-splitting enzyme apyrase, and by monospecific antifibrinogen Fab fragments. The synthetic peptide analog of the platelet receptor recognition site on the gamma chain of fibrinogen, gamma 400-411, inhibited platelet aggregation induced by mutant Re595 (IC50 160 mumol/L), whereas serotonin secretion was unaffected. Tetrapeptide, RGDS, analogous to human fibrinogen alpha chain (alpha 572-575) and to the cell adhesion site of fibronectin, also inhibited aggregation induced by mutant Re595 (IC50 60 mumol/L). Secretion of 14C- serotonin was preceded by a very rapid phosphorylation of a platelet protein of mol wt 47,000, which is associated with protein kinase C activation. Myosin light chain (mol wt 20,000) was also phosphorylated. Both phosphoproteins were dephosphorylated while secretion was reaching maximum. Furthermore, release of 3H-arachidonic acid from platelet phospholipids and generation of thromboxane B2 via the cyclooxygenase pathway were observed. Inhibition of this pathway with acetylsalicylic acid (10(-4) mol/L) or indomethacin (5 X 10(-4) mol/L) reduced 14C- serotonin secretion and platelet aggregation. The role of Lipid A in the interaction of mutant Re595 with human platelets was deduced from the inhibitory effect of the Lipid A-binding protein present in Limulus amebocyte lysate. Likewise, polymyxin B, known to complex with Lipid A, was inhibitory. The reactivity of mutant Re595 toward platelets was attenuated by mild acid hydrolysis, during which KDO was dissociated from the glycolipid, and by alkaline hydrolysis, which breaks ester- linked fatty acids in Lipid A. In contrast to mutant Re595, strain S218 of S minnesota bearing "complete" endotoxic lipopolysaccharide did not induce secretion and aggregation of human platelets.(ABSTRACT TRUNCATED AT 400 WORDS)     

Structure and heterogeneity of the oligosaccharides from the lipopolysaccharides of a pyocin-resistant Neisseria gonorrhoeae.

The compositions and partial structures of the oligosaccharides from the lipopolysaccharides (LPS) of a pyocin-resistant Neisseria gonorrhoeae (strain JW31R) have been determined by liquid secondary ion mass spectrometry (LSIMS), tandem mass spectrometry, and methylation analysis. Four major structures were identified with Mr 2123, 2000, 1961, and 1838, as well as seven species of lower abundance of Mr 1758-1272. The largest of the major oligosaccharides (Mr, 2122) consists of 3-deoxymanno-2-ketooctulosonic acid (KDO)-Hep2GalNAcGlcNAcGal4Glc2 (Hep, heptose) and phosphoethanolamine (PEA). The smaller oligosaccharides are truncated versions of this larger oligosaccharide. The oligosaccharides consist of a common triantennary structure containing KDO at the reducing terminus attached to a heptose disaccharide. A hexose (Hex)2-3 branch is attached to the heptose linked directly to KDO and a GalNAc-Hex3, GlcNAc, and PEA are separately attached to the second heptose. These oligosaccharides are the first structures to be determined for a gonococcal LPS and should further our understanding of the structural and antigenic diversity of these glycolipids.     

Effect of altered lipid A synthesis on the synthesis of major proteins of the Salmonella typhimurium outer membrane

The effect of altered lipid A synthesis on the synthesis of major outer membrane proteins was investigated in mutants of Salmonella typhimurium conditionally defective in the synthesis of 3-deoxy-D-mannooctulosonic acid (KDO). The defect is due to a mutation in the structural gene for KDO-8-phosphate synthetase (designated kdsA), and expression of this lesion results in the accumulation of a precursor of lipid A that not only lacks KDO but is also deficient in ester-linked fatty acyl residues. During the initial 20-30 min following a shift of mutants to nonpermissive conditions, the rate of synthesis of the OmpA protein increased approximately 2.5-fold and then decreased. In contrast, the rates of synthesis of total cell-envelope proteins, as well as that of the porin proteins, were unaffected. The mechanism responsible for the initial increase in the rate of OmpA synthesis remains to be established. However, it appears that the subsequent decrease in the rate of OmpA synthesis may be related to a decrease in the stability of OmpA messenger RNA. The effect of nonpermissive conditions on the rate of OmpA synthesis was specifically related to expression of the kdsA lesion, and it was not found to be strain-specific or uniquely related to a single kdsA mutant allele.     

Chemical and serological investigations on the genus-specific lipopolysaccharide epitope of Chlamydia.

Members of the bacterial genus Chlamydia are responsible for widespread disease among humans and animals, including endemic trachoma in developing countries, venereal disease in developed countries, and a variety of other diseases such as infantile pneumonia and lymphogranuloma venereum. Although there is little genetic relatedness between and large antigenic diversity between and among the two chlamydial species, one antigenic determinant has been preserved among all serovars: the genus-specific lipopolysaccharide epitope. In this report, the tools of molecular genetics, monoclonal antibodies, and analytical and synthetic chemistry have been combined to determine the structure of this epitope. This epitope is attributed to the presence of a trisaccharide of 3-deoxy-D-manno-octulosonic acid (KDO) of the sequence KDOp-(2----8)-KDOp-(2----4)-KDO. The structure includes a unique linkage of two KDO residues through a 2.8-linkage.