Sphaerospora renicola n.sp., a myxosporean from carp kidney,and its pathogenicity

Sphaerospora renicola n.sp. is a common parasite of carp in Czechoslovakia. Its life cycle involves intracellular stages in the epithelial cells of renal tubuli and trophozoite stages proliferating in the tubular lumen, transforming ultimately into pansporoblasts, each having one pansporoblast nucleus and producing two spores. The spores are almost globular with an average size of 7.3×7.2 , with polar capsules of equal size, and may have two slightly protruding tubercles on their shell valves. Differential diagnosis from otherSphaerospora species infecting carp, as well as fromMitraspora cyprini Fujita, is made. Intracellular stages ofS. renicola cause swelling and hyperplasia of the epithelium in renal tubuli followed by dystrophic changes. Accumulation of developmental stages in the tubular lumen provokes pronounced regressive changes of the epithelium, which may be followed by necrosis.     

Establishment of ionic channels and signalling cascades in the embryonic stem cell-derived primitive endoderm and cardiovascular system

The first organ system to be established in early embryogenesis is the cardiovascular system which develops upon interaction with hypoblastic cells of the primitive endoderm. Here we focus on recent work on embryoid bodies derived from pluripotent embryonic stem (ES) cells. Ca(2+) oscillations and Ca(2+) signalling pathways during the differentiation of primitive endodermal cell layers are reported. Furthermore, the development-dependent expression of ion channels and the buildup of signalling cascades involved in the modulation of voltage-dependent L-type Ca(2+) channels during early cardiomyogenesis and the formation of functional vascular structures in the process of vasculogenesis and angiogenesis are reviewed. We also report on the use of green fluorescent protein reporter gene expression under the control of cardiac-specific promoters, e.g. the human cardiac alpha-actin promoter, which enables the identification and in vivo characterization of cardiomyocytes at very early stages of cardiomyogenesis.     

Monocyte chemotactic protein-3 (MCP3) interacts with multiple leukocyte receptors: binding and signaling of MCP3 through shared as well as unique receptors on monocytes and neutrophils

The diversity of monocyte chemotactic protein (MCP)3 target cell types, as well as the capacity of MCP3 to desensitize leukocyte responses to other CC chemokines, suggested that MCP3 may interact with multiple CC chemokine receptors. The purpose of this study is to establish how MCP3 binds and activates monocytes and neutrophils. We show that human monocytes exhibit high-affinity binding for ¹²⁵I-MCP3 with an estimated Kd of 1–3 nM and about 10000 binding sites/cell. The binding of ¹²⁵I-MCP3 to monocytes was progressively less well competed by CC chemokines macrophage inflammatory protein (MIP)lα (Kd = 5–10 nM), RANTES (Kd = 5–10 nM), MCP1 (monocyte chemoattractant and activating factor, or MCAF) (Kd = 60 nM) and MIP1β (Kd > 100 nM). On the other hand, unlabeled MCP3 displaced the binding of radiolabeled MIP1α, RANTES, MCP1 and MIP1β as effectively as the isologous CC chemokines. In agreement with the binding data, pretreatment of monocytes with MCP3 completely desensitized the calcium flux in response to MIP1α and RANTES. However, MIP1α and RANTES failed to desensitize the response of monocytes to MCP3. MCP3 and MCP1 partially desensitized each other's effects on monocytes. These binding and cross-desensitization results suggest that MCP3 binds and signals through other binding sites in addition to those shared with MIP1α, RANTES and MCP1. The unidirectional competition for MIP1β binding and signaling by MCP3 suggests the existence of an as-yet unidentified site for MCP3 shared with MIP1β. The existence of another unique binding site(s) for MCP3 was further shown by the failure of any of the other CC chemokines to compete effectively for MCP3 binding on neutrophils. MCP3 in our study was also the only human CC chemokine that consistently chemoattracted neutrophils. These results suggest that MCP3 is a ligand that can bind and activate a broad range of target cells through receptors shared by other CC chemokines as well as its own receptor.     

大鼠重组IgE Fc区CH2-3的原核表达及活性研究

目的 研究大鼠IgE的Fc区CH2-3的生物学活性。方法 构建大鼠IgE的Fc区CH2-3的原核表达质粒pBAD／gⅢA／Ch2-3，并转化入TOP10中，阿拉伯糖诱导表达、周质腔抽提、Ni-NTA金属鳌合柱纯化获得大鼠IgE的Fc区CH2-3，细胞及动物水平检测蛋白质生物学活性。结果 原核系统表达出大鼠IgE的Fc区CH2-3，它能够阻断OVA激发的RBL-2H3的脱颗粒反应，阻断被动皮肤实验。结论 大鼠IgE的Fc区CH2-3能够封闭IgE高亲和力受体，阻断过敏反应。     

Transition between two forms of heterochromatin at plant subtelomeres

The manner of packing of the terminal DNA loci into nucleosomes and higher order structures may strongly influence their functional interactions. Besides the structural flexibility of telomeric DNA sequences, conserved features of their chromatin including short nucleosome phasing (157 bp) and nucleosome sliding have been described previously. To gain a complementary knowledge of subtelomeres, we have analysed the chromatin structure of two subtelomeric tandem repeats from the plant Silene latifolia: X43.1 and 15Ssp. X43.1 shows two distinct nucleosome periodicities – 157 and 188 bp. Preferred positions of its two nucleosomes have been mapped at both low and high resolution and the experimental results correspond to computer-predicted positions. 15Ssp is a newly-discovered sequence showing a telomere-associated position by PCR and a subtelomeric location by pulsed-field gel electrophoresis and fluorescence in situ hybridisation. Its 159 bp sequence unit shows a tandem arrangement and the presence of micrococcal nuclease-hypersensitive sites when either naked DNA or chromatin is digested. Use of a chemical nuclease results in a regular nucleosome ladder of 157 bp periodicity. Moreover, 15Ssp mononucleosomes show instability and absence of specific positioning, features typical for telomeric chromatin. This revised version was published online in July 2006 with corrections to the Cover Date.     

HIV－1Protease在大肠杆菌中的高表达

艾滋病的致病因子为人免疫缺陷病毒。该病毒的蛋白酶在病毒复制和成熟中具有决定性的意义。由于目前国内外尚未获得艾滋病病毒蛋白酶高效表达的重组子及简便的活性检测系统，限制了它的研究与应用。本文将用ＰＣＲ技术修饰的ＨＩＶＰｒ基因克隆入原核高效表达载体ｐＴＴＱ１８的ＥｃｏＲⅠ和ＨｉｎｄⅢ酶切位点之间，并用豆芽核酸酶将ＥｃｏＲⅠ的粘端削平，构建了读框正确的表达载体，ＩＰＴＧ诱导表明，该重组子在大肠杆菌中获得了高表达，激光扫描结果表明：重组的ＨＩＶＰｒ占细菌总蛋白８．９％以上。     

应用多层螺旋CT对耳硬化症的术前评估价值

目的:评估MDCT在术前耳硬化症诊断中的作用。方法:收集经临床证实为耳硬化症、且CT扫描采用螺旋扫描病例共18例,采集的数据传输到4.1工作站,进行多平面重建。结果:18例共36耳显示异常:单独前庭窗异常18耳,表现为前庭窗扩大或狭小,周围骨质密度降低或镫骨底板板密度增高;前庭窗及蜗窗同时受累共8耳;主要累及耳蜗周围迷路骨质10耳,表现为耳蜗骨迷路边缘不整,呈条片状密度减低或双环征。MPR交互重建充分显示了所有重要解剖结构的位置、形态:其中3耳为颈静脉球高位。结论:MDCT可以正确显示耳硬化症病灶的细微改变,提供详细的术前诊断信息;结合MPR技术可全面观察病变范围,并充分显示颞骨内重要解剖结构的位置和形态。对于手术方案的设计、防止手术并发症和提高疗效等具有重要意义。     

磷酸组织胺诱导的Ⅰ型超敏反应对肝损伤作用的研究

目的:通过观察与Ⅰ型超敏反应相关的生物活性介质--组织胺对家兔肝脏有无直接损伤作用,进一步论证Ⅰ型超敏反应对肝脏的损伤作用.方法:选择34只家兔随机分为对照组、实验Ⅰ组和实验Ⅱ组3组;对照组只进行正常饲料喂养,实验Ⅰ组在正常饲料喂养的同时每天给予0.4μg/kg耳静脉注射磷酸组胺注射液,实验Ⅱ组在正常饲料喂养的同时每天给予0.08 μg/kg耳静脉注射磷酸组胺注射液;动态观察以上3个组的血清谷丙转氨酶(ALT)及血清谷草转氨酶(AST)变化;利用光学显微镜观察以上3个组肝组织的病理变化.结果:无论是实验Ⅰ组或实验Ⅱ组,经过一段时间的观察,发现血清内ALT和AST含量均显着高于对照组(P＜0.01),但Ⅰ、Ⅱ组之间无显着性差异(P＞0.05);实验Ⅰ组和实验Ⅱ组在显微镜下观察,其肝脏均有不同程的损伤和病理改变,且实验Ⅱ组的损伤和变化大于实验Ⅰ组,而对照组的肝脏则无明显的病理变化.结论:组织胺对家兔肝脏确实有一定的损伤作用,而且随着投予剂量和时间的增加,肝脏的损伤和病理变化也越显著;通过本研究,可以得出Ⅰ型超敏反应导致肝脏病理变化及损伤的见解.