液氮保种对田鼠巴贝虫标准株存活力的影响

目的探索液氮保种对田鼠巴贝虫标准株存活力的影响。方法液氮保种1、3、6、9个月的田鼠巴贝虫标准株小鼠血室温复苏后感染正常BALB/c小鼠各3只(复苏1代,实验组),100μL/只;同时取3只新感染田鼠巴贝虫活体保藏小鼠为对照组。实验组染虫率达高峰时再接种正常BALB/c小鼠(复苏2代),观察田鼠巴贝虫的形态变化及增殖情况,并观察不同保存时间复苏1代及复苏2代的染虫率情况。结果液氮保种田鼠巴贝虫与活体保种的田鼠巴贝虫相比,形态变化不大,都会出现小滋养体、环状滋养体、裂殖体及未成熟和成熟裂殖子等多种形态。液氮复苏1代首次查见虫体及达到染虫率高峰的时间比动物保种延迟1~2d,但复苏2代即恢复一致。田鼠巴贝虫染虫全血经液氮保存1、3、6、9个月,仅达到高峰期时间延迟,其存活力未见明显下降。结论液氮保种对田鼠巴贝虫形态及存活力影响小,可成为一种较好的保存方式。     

隐孢子虫病实验与临床研究——Ⅲ.实验小鼠隐孢子虫病透射电镜观察

描述对免疫抑制小鼠肠上皮细胞寄生的隐孢子虫滋养体、裂殖体和大配子的超微结构及肠上皮细胞改变的透射电镜观察结果。虫体在肠上皮细胞附着处可见一明显电子致密带,并被肠上皮细胞来源的纳虫空泡包围。虫体在附着处其胞浆膜形成复杂的膜性皱褶并和肠上皮细胞质膜紧密接触。在裂殖子内可见电子致密颗粒和棒状体样结构,其意义尚不明瞭。     

隐孢子虫病实验与临床研究Ⅲ.实验小鼠隐孢子虫…

描述对免疫抑制小鼠肠上皮细胞寄生的隐孢子虫滋养体、裂殖体和大配子的超微结构及肠上皮细胞改变的透射电镜观察结果。虫体在肠上皮细胞附着处可见一明显电子致密带，并被肠上皮细胞来源的纳虫空泡包围。虫体在附着处其胞浆膜形成复杂的膜性皱褶并和肠上皮细胞质膜紧密接触。在裂殖子内可见电子致密颗粒和棒状体样结构，其意义尚不明了。     

田鼠巴贝虫隐性感染鼠再感染、免疫抑制或盲传后的虫密度消长规律研究

目的观察田鼠巴贝虫(Babesia microti)隐性感染期小鼠经再感染、免疫抑制或盲传健康小鼠后的外周血红细胞内虫体密度的消长规律。方法取1只感染种鼠的外周血(虫密度为20%),腹腔接种6周龄雌性BALB/c健康小鼠12只,100μl/只,用随机数字表法分为对照组、再感染组、免疫抑制组和盲传组,每组3只。4组感染小鼠连续28 d尾部采血,吉氏染色法观察田鼠巴贝虫形态变化,并计算红细胞染虫率,构建隐性感染小鼠模型。再感染组隐性感染小鼠再次腹腔接种相同剂量的田鼠巴贝虫感染种鼠血;免疫抑制组隐性感染小鼠腹腔注射地塞米松,0.5 mg/只,连续注射5 d;盲传组3只隐性感染小鼠取眼眶血,分别腹腔盲传接种健康雌性BALB/c小鼠各3只,100μl/只。3组小鼠继续尾部采血28 d,镜下计数感染红细胞,计算染虫率,并观察田鼠巴贝虫形态变化。结果对照组、再感染组、免疫抑制组和盲传组小鼠外周血均于感染后第3天查见田鼠巴贝虫体,第7天红细胞染虫率最高,分别为73.2%、78.0%、76.2%及79.0%,随后染虫率逐渐下降,至第28天外周血镜检阴性,进入隐性感染阶段。再感染组小鼠再次感染后28 d内,每天染虫率均为0。免疫抑制组小鼠在免疫抑制后第2天查见虫体,第12天染虫率再次达到高峰,为65.2%,随后逐渐下降,至第22天再次进入隐性感染期。盲传组新感染的9只小鼠在感染后第4天查见虫体,第9~10天染虫率达到高峰,为35.0%~39.0%,随后逐渐下降,至第28天小鼠进入隐性感染阶段。各组感染的田鼠巴贝虫形态变化基本一致,染虫初期以小环状体居多;染虫高峰期多见大环状体和长丝状体;有多虫寄生现象。结论田鼠巴贝虫隐性感染期小鼠有带虫免疫现象,并可作为传染源;经免疫抑制后虫体被激化,可出现与首次感染相同的虫体密度消长规律。     

疟原虫表面蛋白与细胞入侵

业已证实子孢子和裂殖子表面固有的或由特定细胞器赋于虫体表面的一些蛋白作为配体与宿主细胞表面受体结合。氨基酸序列分析提供了与入侵过程有关的一级结构基序。环子孢子蛋白和最初定位于微线体的子孢子表面蛋白-2含有可介导识别肝细胞表面硫酸多糖的氨基酸序列;裂殖子表面蛋白-1可能与红细胞的识别有关,这种蛋白在合成和侵入红细胞过程中进行了一系列复杂的修饰。其他位于裂殖子顶端的蛋白为红细胞或网织红细胞的结合蛋白。     

疟原虫表面蛋白与细胞入侵

业已证实子孢子和裂殖子表面固有的或由特定细胞器赋于虫体表面的一些蛋白作为配体与宿主细胞表面受体结构。氨基酸序列分析提供了与入侵过程有关的一级结构基序。环子孢子孢子蛋白和最初定位于微线体的子孢子表面蛋白－２含有可介导识别肝细胞表面硫酸多糖的氢基酸序列；裂殖子表面蛋白－１可能与红细胞的识别有关，这种蛋白在合成和侵入红细胞过程中进行了一系列复杂的修饰。其他位于裂殖子顶端的蛋白为红细胞或网织红细胞的结合蛋     

田鼠巴贝虫可溶性虫体蛋白的质谱鉴定及生物信息学分析

目的利用蛋白质组学及生物信息学方法对田鼠巴贝虫可溶性虫体蛋白进行分析。方法取田鼠巴贝虫阳性全血腹腔接种BALB/c小鼠,构建感染小鼠模型。取感染高峰期小鼠染虫血分离红细胞,Percoll密度梯度离心法富集田鼠巴贝虫虫体,冻融及超声法获得可溶性虫体蛋白。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)鉴定虫体蛋白相对分子质量分布,将含有可溶性虫体蛋白的凝胶按相对分子质量分为2个样品,采用电喷雾质谱鉴定法进行质谱鉴定。采集质谱鉴定数据,搜索Uniprot KB数据库中的巴贝虫、田鼠巴贝虫RI株和恶性疟原虫蛋白数据库。将鉴定到的蛋白与NCBI nr数据库中的蛋白序列进行比对,利用Blast2GO(Version2.8.0)中的Mapping功能对所有定量到的蛋白比对序列所关联的GO功能条目进行提取,用GO注释将鉴定到的虫体蛋白进行生物过程、分子功能和细胞组分分析。利用KAAS将目标蛋白序列与KEGG GENES数据库中的巴贝虫蛋白序列进行比对,通过同源/相似蛋白的KO号注释到相关KEGG通路上。结果Percoll梯度离心法获得富集后的田鼠巴贝虫虫体,通过冻融及超声法获得可溶性虫体蛋白,经SDS-PAGE鉴定发现有5条主带及7条次带。经质谱鉴定并与巴贝虫、田鼠巴贝虫RI株和恶性疟原虫蛋白数据库比对,分别鉴定到757、600和138个蛋白,其中独特肽段为2及以上的蛋白分别为368、375和12个。进一步分析发现,独特肽段数较多的蛋白为表面抗原或分泌抗原类蛋白、蛋白酶类、热休克家族蛋白及棒状体相关蛋白等。生物信息学分析,田鼠巴贝虫可溶性虫体蛋白按参与的生物过程共获得876条注释,按分子功能共获得219条注释,按细胞组分结果显示,共获得146条注释。通过同源/相似蛋白的KEGG注释,共提取到与可溶性虫体蛋白序列相关的172条KEGG信号/代谢通路。结论利用质谱鉴定及生物信息学方法分析田鼠巴贝虫可溶性虫体蛋白主要含有分泌蛋白、蛋白酶类和HSP家族成员蛋白。     

疟原虫红内期不需要凝血酶原激活剂

成熟裂殖体引起红细胞破裂以及随后游离的裂殖子再侵入新的红细胞是疟原虫红内期的两个主要过程,大量证据表明虫体和/或宿主的蛋白酶(主要是丝氨酸及半胱氨酸蛋     

福建省1例人巴贝虫病的诊断与鉴定

目的 分析1例人感染巴贝虫的实验室资料,提高对巴贝西虫病的诊断水平。方法 观察外周血中虫体的形态;从患者外周血中提取的DNA核酸,采用田鼠巴贝虫种特异性引物进行聚合酶链反应(PCR)。采用PCR扩增田鼠巴贝虫18S rRNA片段,取阳性PCR产物送测序并进行序列比对分析。结果 外周血中见大量疑似恶性疟原虫虫体;PCR产物测序结果经过BLAST比对,与田鼠巴贝虫18s核糖体DNA序列有99%的同源性。结论 感染的虫体为田鼠巴贝虫。福建省部分地区鼠类(尤其是野鼠)存在田鼠巴贝虫感染,是巴贝虫病的自然疫源地,必须引起足够的重视。     

输入染虫成分血对BALB/c小鼠感染田鼠巴贝虫的影响

目的　观察静脉注射含田鼠巴贝虫的不同成分血对小鼠巴贝虫感染的影响。方法　以田鼠巴贝虫感染健康小鼠后眼眶采血，制备染虫全血、去除血清的成分血及纯红细胞。将27只小鼠随机分为3组，分别为全血组、无血清染虫组、纯红细胞组，每组9只；每组设3个亚组，每个亚组3只，每只分别通过尾静脉注射100 μL浓度为9.00、0.90、0.09只/μL（分别含900、90、9只巴贝虫虫体）的相应成分血。接种当天记为D0，自D1起每隔1 d于小鼠尾尖采血涂薄血涂片，吉氏染色液染色后镜检观察各组小鼠红细胞染虫率。结果　注射900只田鼠巴贝虫后，全血组、无血清组均于D3在外周血中查见巴贝虫，于D15虫密度开始升高，并于D21虫密度达高峰，红细胞染虫率分别为2.21%和1.76%；随后虫密度下降，D31染虫率趋于0；而纯红细胞组小鼠在观察期间未查见巴贝虫感染。注射90只田鼠巴贝虫，仅全血组于D3在外周血查见巴贝虫虫体，D15虫密度升高，D21虫血症达高峰，红细胞染虫率为1.35%，D31染虫率趋于0；无血清组和纯红细胞组实验期间外周血中未查见巴贝虫。注射9只田鼠巴贝虫，全血组、无血清组和纯红细胞组外周血中均未查见虫体。结论　血液成分及感染虫数可能对小鼠静脉注射感染巴贝虫有一定影响，输入成分血仍存在感染巴贝虫的风险。     

间日疟原虫红细胞内期电镜观察

间日疟原虫裂殖子钻入红细胞后,早期环状体呈哑铃形,其纳虫空泡内膜状物质通过红细胞中狭窄通道排出。滋养体形状不规则,或呈卵圆形,由单层表膜包绕,细胞质内具有无嵴线粒体,纳虫空泡中有电子致密颗粒。配子体形状规则,几乎充满被寄生的红细胞,由两层表膜包绕,细胞质内具有有嵴线粒体。雌配子体细胞质内核糖体、嗜锇小体和线粒体都比雄配子体丰富。被寄生的红细胞的3个主要变化为出现小泡、细胞质裂隙和凹窝小泡复合物。后者沿红细胞表膜分布,可能是薛氏小点。     

鼠疟原虫裂殖子进入红细胞后的早期超微结构演化

为了探讨疟原虫红内早期超微结构的演化，用透射电镜观察了伯氏和约氏疟原虫。裂殖子入侵后补围于内陷红细胞膜所构成的纳虫泡中，起初停留于浅层红细胞浆内，造成该处表面隆起。虫体浑圆，顶端结构很快消失，球形体与核和线粒体分离并萎缩。分离了的线粒体略显舒展，内质网扩大。核变长弯形，核周隙有部分地扩大。双层内膜渐与外膜分离，断裂、卷曲、以至消失。最后变成单层质膜的滋养体。早期滋养体的组织结构仍较精细，以后密度逐渐减低。胞浆内有个别多角形的大内质网池，质膜下出现小食物泡。然后虫体变扁平，边缘卷起，包围红细胞浆，终至封口融合，形成一个食物泡；接着在其旁出现消化泡和色素粒。长成更大的中期滋养体。     

双氢青蒿素对大鼠体内卡氏肺孢子虫作用的超微结构研究

目的 研究双氢青蒿素（DHA）治疗对大鼠体内卡氏肺孢子虫（PC）超微结构的影响。方法 以地塞米松磷酸钠对Wistar大鼠进行皮下注射，建立卡氏肺孢子虫肺炎（PCP）动物模型，用60mg／kgDHA治疗实验大鼠，杀鼠取肺，用透射和扫描电镜观察大鼠肺内PC的超微结构变化，并与感染对照组进行比较。结果 透射电镜发现PC滋养体表膜和核膜破裂，胞质中出现大量空泡和高电子密度颗粒，PC包囊中也出现空泡，囊内小体变性坏死；扫描电镜发现PC滋养体丝状伪足和微绒毛稀疏、变短甚至脱落，表膜出现缺损。结论 DHA可破坏PC滋养体和包囊。     

慢性乙型肝炎及肝硬化患者肝脏微循环改变

为探讨慢性乙型肝炎（慢乙肝）及肝硬化患者的肝脏微循环状态。对141例慢乙肝、12例肝硬化患者和2例正常人的肝组织进行HE染色,光镜观察,并对其中53例慢乙肝和2例肝硬化患者的肝组织进行了电镜观察。结果显示,正常人的肝窦腔通畅,无狭窄和闭塞,无红细胞聚集现象。慢乙肝患者86.52%有肝窦腔狭窄,60.28%肝窦腔内见红细胞聚集,34.04%肝窦腔内有血栓形成;电镜观察见94.34%的患者肝窦内皮细胞窗孔减小减少,33.96%有基底膜形成,24.53%狄氏腔内出现胶原纤维。肝硬化患者肝组织结构紊乱,肝腺泡消失,假小叶形成。提示慢乙肝患者存在肝脏微循环障碍,肝硬化时肝脏微循环结构丧失。     

Plasmodium falciparum cysteine protease falcipain-2 cleaves erythrocyte membrane skeletal proteins at late stages of parasite development

Plasmodium falciparum-derived cysteine protease falcipain-2 cleaves host erythrocyte hemoglobin at acidic pH and specific components of the membrane skeleton at neutral pH. Analysis of stage-specific expression of these 2 proteolytic activities of falcipain-2 shows that hemoglobin-hydrolyzing activity is maximum in early trophozoites and declines rapidly at late stages, whereas the membrane skeletal protein hydrolyzing activity is markedly increased at the late trophozoite and schizont stages. Among the erythrocyte membrane skeletal proteins, ankyrin and protein 4.1 are cleaved by native and recombinant falcipain-2 near their C-termini. To identify the precise peptide sequence at the hydrolysis site of protein 4.1, we used a recombinant construct of protein 4.1 as substrate followed by MALDI-MS analysis of the cleaved product. We show that falcipain-2-mediated cleavage of protein 4.1 occurs immediately after lysine 437, which lies within a region of the spectrin-actin-binding domain critical for erythrocyte membrane stability. A 16-mer peptide containing the cleavage site completely inhibited the enzyme activity and blocked falcipain-2-induced fragmentation of erythrocyte ghosts. Based on these results, we propose that falcipain-2 cleaves hemoglobin in the acidic food vacuole at the early trophozoite stage, whereas it cleaves specific components of the red cell skeleton at the late trophozoite and schizont stages. It is the proteolysis of skeletal proteins that causes membrane instability, which, in turn, facilitates parasite release in vivo.     

Effect of metalloprotease inhibitors on invasion of red blood cell by Plasmodium falciparum

For successful invasion, the malaria merozoite needs to attach to the red blood cell membrane, undergo reorientation, form a junction of the apical end with the host membrane, and internalize. Malaria proteases have been implicated in the invasion process, but their specific cellular functions remain unclear. To demonstrate the involvement of metalloprotease in the process of Plasmodium falciparum merozoite entry into host red blood cell, schizont-infected red blood cells and parasitophorous vacuolar membrane-enclosed merozoite structures were treated with 1,10-phenanthroline, a metal chelator, resulting in a reduction of invasion with IC50 value of 25 and 29 microM, respectively. Absence of an accumulation of schizont stages after treatment with 1,10-phenanthroline indicated that the inhibitory effect was not due to suppression of merozoite release from red blood cells, but on the invasion step. Although treatment with GM6001, a well-known inhibitor of the mammalian matrix and disintegrin metalloprotease family, was less effective, nevertheless this study points to the importance of metal-requiring protease in the process of invasion of host red blood cell by the malaria parasite.     

Localization and Role of Calcium in the Erythrocyte Coat: Effects of Enzymes and Storage

S ummary . The effects of various treatments on erythrocyte shape, surface, cell coat and calcium binding sites have been investigated by means of high voltage electron microscopy (HVM), scanning electron microscopy (SEM) and conventional electron microscopy (TEM). Papain caused the formation of small blisters within the cellular surface as well as crenation and'budding'of the erythrocytes. Afer neuraminidase treatment, long filaments were observed to radiate from the surface of the erythrocyte. The other enzymes investigated, RNAse, DNAse, phospholipase, protease and trypsin, produced no demonstrable effect on the cellular structure, nor (with the possible exceptionof trypsin) on the cell coat as seen by subsequent staining with ruthenium red. Putative calcium binding sites on and in the erythrocyte membrane were demonstrated. Following incubation with radioactive calcium, activity was found in the erythrocyte membranes. Calcium binding could be reduced by prior treatment of the erythrocyte with EDTA, neuraminidase, and to a lesser extent, by papain and trypsin. Other enzymes had no demonstrable effect. Stored erythrocytes showed a progressive diminution in calcium binding over a period of up to 4 weeks.     

Intracellular structures of normal and aberrant Plasmodium falciparum malaria parasites imaged by soft x-ray microscopy

Soft x-ray microscopy is a novel approach for investigation of intracellular organisms and subcellular structures with high spatial resolution. We used x-ray microscopy to investigate structural development of Plasmodium falciparum malaria parasites in normal and genetically abnormal erythrocytes and in infected erythrocytes treated with cysteine protease inhibitors. Investigations in normal red blood cells enabled us to recognize anomalies in parasite structures resulting from growth under unfavorable conditions. X-ray microscopy facilitated detection of newly elaborated structures in the cytosol of fixed, unstained, intact erythrocytes, redistribution of mass (carbon) in infected erythrocytes, and aberrant parasite morphology. In cysteine protease inhibitor-treated, infected erythrocytes, high concentrations of material were detected in abnormal digestive vacuoles and aggregated at the parasite plasma membrane. We have demonstrated that an abnormal host erythrocyte skeleton affects structural development of parasites and that this aberrant development can be detected in the following generation when parasites from protein 4.1-deficient red blood cells infect normal erythrocytes. This work extends our current understanding of the relationship between the host erythrocyte membrane and the intraerythrocytic malaria parasite by demonstrating for the first time that constituents of the erythrocyte membrane play a role in normal parasite structural development.     

Pseudo-angiomatous growth pattern in recurrent plasma cell myeloma

Erythrocytes are remarkably dynamic structures, possessing multiple and complex pathways for regulating cell membrane properties to compensate for the absence of a nucleus and internal membranes. Unlike the invasion strategies of many viruses and bacteria into their eukaryotic hosts, however, the accepted model for malaria parasite entry into human erythrocytes casts the host cell in a largely passive role. This is in contrast to mounting evidence for a suite of dynamic alterations that the erythrocyte membrane undergoes during the rapid process of invasion by the blood stage malaria parasite – the merozoite. Here we review the cellular and molecular basis for merozoite invasion of the erythrocyte and explore the idea that radical changes in the erythrocyte membrane protein and lipid architecture probably accompany this key step in the establishment of human malaria disease.     

Effect of glucose-6-phosphate dehydrogenase deficiency on some biophysical properties of human erythrocytes

Abstract

The most widespread erythrocyte enzyme defect throughout the world is glucose-6-phosphate dehydrogenase (G-6-PD) deficiency. The diagnosis of G-6-PD deficiency may be missed during an acute hemolytic episode due to increased young red blood cells which have good enzyme activity. However this might be detected at a later stage when the patient is asymptomatic. This calls for a detailed investigation of the patient with an acute attack of hemolysis at a later stage. Blood samples were obtained from 45 G-6-PD deficient male patients with previously diagnosed disease [25 subjects were during hemolytic attack (Gp1) while the rest was outside acute hemolytic crisis (Gp2)] and 20 healthy male subjects. The effect of G-6-PD deficiency on the erythrocytes of the above groups was investigated by scanning electron microscope (SEM) complemented with dielectric spectroscopy. The quantification of the morphological shape changes revealed that Gp1 had a significant increase in spheroechinocytes as well as in the morphological index in comparison with those of all other groups. The overall electrical and morphological properties of the red cell membrane of these subjects modified to a great extent during hemolytic attack. This may have important diagnostic and research implications. Thus the combined application of dielectric spectroscopy and SEM can be used as an efficient manner for monitoring abnormalities in blood and erythrocytes due to G-6-PD deficiency.