Adherence of ovine and human Bordetella parapertussis to continuous cell lines and ovine tracheal organ culture

The adherence of ovine and human isolates of Bordetella parapertussis to ovine and human continuous culture cell lines and to ovine tracheal organ culture was compared. Adherence to non-ciliated respiratory continuous culture cells did not reveal any host-specificity of the isolates. In contrast, adherence of ovine B. parapertussis strains to ciliated ovine tracheal organ culture was significantly greater than that of human strains. These results indicate that tracheal organ culture is a useful tool for studying host-specific adherence of B. parapertussis and suggest that adherence of B. parapertussis to ciliated epithelia is species-specific making it unlikely that the transfer of B. parapertussis between humans and sheep will result in an infection.     

白头鹎的代谢率与器官重量在季节驯化中的可塑性变化

动物能量代谢的生理生态特征与物种的分布和丰富度密切相关,基础代谢率(BMR)是恒温动物维持正常生理机能的最小产热速率,是动物在清醒时维持身体各项基本功能所需的最小能量值,是内温动物能量预算的重要组成部分.本研究测定了白头鹎(Pycnonotus sinensis)的BMR、内部器官(肝、心、肌胃、小肠、肾和整体消化道)和肌肉的重量,分析了白头鹎内部器官和肌肉重量的季节性变化及与BMR的关系.方差分析表明,白头鹎的BMR存在明显的季节性变化,冬季较高,夏季最低.其内部器官及肌肉重量的变化同样有明显的季节性.相关分析表明,白头鹎的BMR与肝、心、消化道等内部器官和肌肉重量存在明显的相关性.     

ConA引起小鼠肝损伤实验研究

目的探讨conA引起免疫性肝损伤机实验条件。方法测定两个浓度,不同时间点ConA尾静脉注射后小鼠转氨酶水平及肝、脾病理变化。结果15mg／kgConA尾静脉注射后8h,血清转氨酶升高,但病检无明显改变;20mg／kgConA尾静脉注射,脾指数6h达峰值,10h肝脏病理变化显著,转氨酶水平达峰值。结论20mg／kgConA小鼠尾静脉注射6h后脾病变达高峰,10h可引起显著性肝损害。     

Cold-induced apoptosis of hepatocytes: mitochondrial permeability transition triggered by nonmitochondrial chelatable iron

We previously described that the cold-induced apoptosis of cultured hepatocytes is mediated by an increase in the cellular chelatable iron pool. We here set out to assess whether a mitochondrial permeability transition (MPT) is involved in cold-induced apoptosis. When cultured hepatocytes were rewarmed after 18 h of cold (4°C) incubation in cell culture medium or University of Wisconsin solution, the vast majority of cells rapidly lost mitochondrial membrane potential. This loss was due to MPT as assessed by confocal laser scanning microscopy and as evidenced by the inhibitory effect of the MPT inhibitors trifluoperazine plus fructose. The occurrence of the MPT was iron-dependent: it was strongly inhibited by the iron chelators 2,2′-dipyridyl and deferoxamine. Addition of trifluoperazine plus fructose also strongly inhibited cold-induced apoptosis, suggesting that the MPT constitutes a decisive intermediate event in the pathway leading to cold-induced apoptosis. Further experiments employing the non-site-specific iron indicator Phen Green SK and specifically mitochondrial iron indicators and chelators (rhodamine B-[(1,10-phenanthrolin-5-yl)aminocarbonyl]benzyl ester, RPA, and rhodamine B-[(2,2′-bipyridin-4-yl)aminocarbonyl]benzyl ester, RDA) suggest that it is the cold-induced increase in cytosolic chelatable iron that triggers the MPT and that mitochondrial chelatable iron is not involved in this process.     

Role for laminin-alpha5 chain LG4 module in epithelial branching morphogenesis

Laminin-alpha5 chain was localized in all epithelial basement membranes (BMs) of mouse submandibular gland (SMG) from the onset of branching morphogenesis and became restricted to BMs of epithelial ducts in the adult. To investigate whether the laminin-alpha5 chain plays a role in branching morphogenesis, a set of cell-adhesive peptides from the C-terminal globular domains (LG1-5) was tested for their effects in SMG organ cultures. One peptide, LVLFLNHGH (A5G77f), which represents a sequence located in the connecting loop between strands E and F of LG4, perturbed branching morphogenesis and resulted in irregularities in the contours of epithelial structures, with formation of deep clefts. The data suggest a role for the laminin-alpha5 LG4 module in the development of the duct system, rather than in the bifurcation of epithelial clusters. The epithelial BM of A5G77f-peptide-treated explants was continuous, which was in contrast to our previous finding of impaired epithelial BM assembly in explants treated with the laminin-alpha1 LG4 module peptide, or with a monoclonal antibody against this domain. A5G77f also perturbed in vitro development of lung and kidney. These results suggest a crucial role for the LG4 module of laminin-alpha5 in epithelial morphogenesis that is distinct from that of the laminin-alpha1 LG4.     

Human recombinant stem cell factor promotes spermatogonial proliferation,but not meiosis initiation in organ culture of newt testis fragments

We previously showed that mammalian FSH stimulates the proliferation of newt spermatogonia and induces their differentiation into primary spermatocytes in vitro. In the current study, to examine a possibility that stem cell factor (SCF) is involved in the proliferation of newt spermatogonia and/or their differentiation into primary spermatocytes, human recombinant SCF (rhSCF) was added to organ culture of testicular fragments. rhSCF was found to stimulate the spermatogonial proliferation and the spermatogonia progressed to the seventh generation that is the penultimate stage before primary spermatocyte stage. However, the spermatogonia did not differentiate into primary spermatocytes, but instead died of apoptosis. These results indicate that rhSCF promotes the proliferation of newt spermatogonia, but not the initiation of meiosis.     

Tissue distribution of cytosolic beta-elimination reactions of selenocysteine Se-conjugates in rat and human

Selenocysteine Se-conjugates (e.g. methylselenocysteine) have been shown to be potent chemopreventive and chemoprotective agents, and inducers of apoptosis. Although the mechanism of action remains to be elucidated, beta-elimination of these compounds by beta-lyase enzymes into corresponding selenols, pyruvate and ammonia is thought to be critical. This study describes in vitro beta-lyase activity in nine rat organs using three selenocysteine Se-conjugates and S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine. For all substrates the highest beta-elimination rates were found in kidney, followed by liver, while brain, spleen, heart, large and small intestine, thyroid and lung were of minor importance. Since liver plays an important role in beta-elimination, hepatic beta-lyase activity was extensively studied using 23 selenocysteine Se-conjugates and S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine and was compared with previously obtained renal beta-lyase data. The results showed that hepatic beta-lyase activities were 4-25-fold lower than the corresponding renal beta-lyase activities. Hepatic beta-elimination of the substrates appeared to be exclusively catalyzed by the pyridoxal 5'-phosphate-dependent beta-lyase enzyme kynureninase. Studies performed with human hepatic cytosols of three individuals showed that hepatic beta-lyase activity was 2-5-fold higher when compared with the previously obtained human renal activity. Significant correlation was obtained between human hepatic beta-lyase activities of three individuals. The relevance of this data for using SeCys-conjugates as chemopreventive and a chemoprotective agent is discussed. Based on the large differences in organ-selective beta-elimination and specific beta-lyase activity between rat and humans, the rat might not be a good model to investigate nephrotoxicity of cysteine S-conjugates, and chemoprevention and chemoprotection of SeCys-conjugates in man.     

哲罗鱼消化系统器官发生发育的组织学观察

采用形态观察与连续组织切片技术,对哲罗鱼(Hucho taimen)胚胎期(水温7~8℃)和胚后期(水温3~14℃)消化系统的发生发育进行观察和研究。结果表明,哲罗鱼受精11d形成原始的消化管。受精18d肝原基出现,U型胃雏型形成。受精30d鱼体破膜,口能自由闭合。破膜8d后,齿形成,肛门与外界相通,消化道初步形成口咽腔、食道、U型胃、肠和肛门。破膜16d,胰及瓣囊出现,仔鱼消化系统初步具备了摄食和消化外源性食物的能力。破膜24d后,鱼体开始上浮,主动摄食,由内源性营养转向混合性营养。破膜30d后,卵黄囊完全被吸收,各消化器官功能和结构逐步发育完善,鱼体由混合性营养进入外源性营养阶段。此后随着鱼体的生长消化器官逐步发育成熟,舌齿和下颌齿分别为双排,胃腺发达,形成网状结构,幽门盲囊较多,肠为直行,肝和胰为相互分开的独立器官。