Blockade of L-type voltage-gated Ca channel inhibits ischemia-induced neurogenesis by down-regulating iNOS expression in adult mouse

Neurogenesis in the adult mammalian hippocampus may contribute to repairing the brain after injury. The signals that regulate neurogenesis in the dentate gyrus following ischemic stroke insult are not well known. We have previously reported that inducible nitric oxide synthase (iNOS) expression is necessary for ischemia-stimulated neurogenesis in the adult dentate gyrus. Here, we show that mice subjected to 90 min of middle cerebral artery occlusion (MCAO) significantly increased the number of new neurons and up-regulated iNOS expression in the dentate gyrus. Blockade of the L-type voltage-gated Ca(2+) channel (L-VGCC) prevented neurogenesis in the dentate gyrus and subventricular zone (SVZ), and down-regulated iNOS expression in the dentate gyrus after cerebral ischemia. This study suggests that Ca(2+) influx through L-VGCC is involved in ischemia-induced neurogenesis by up-regulating iNOS expression.     

A new method for the determination of critical polyethylene glycol concentration for selective precipitation of DNA fragments

Separation strategies based on size-selective precipitation of DNA fragments with polyethylene glycol (PEG) have been used for achieving desired DNA interval in automated sample preparation for next-generation sequencing. By varying PEG concentration, DNA fragments of different sizes can be precipitated onto surfaces of carboxyl-coated paramagnetic particles selectively, and therefore, the desired DNA interval can be obtained. However, one of the crucial points in this approach is to determine the critical PEG concentration for DNA fragment of a certain size. The aim of this work was to develop a convenient and reliable method for accurately determining the critical PEG concentration. In our method, at a fixed concentration of sodium chloride (NaCl), recovered DNA samples obtained with different PEG concentrations were directly quantified, and their concentrations as a function of the PEG concentration were fitted by the logistic function. The critical PEG value was easily and accurately determined from the fitted logistic function. The repeatability and stability of the critical PEG value were assessed, showing an excellent reliability of the method. Based on this method, critical PEG values of different-size DNA fragments were determined at different NaCl concentrations. The effectiveness of the method was also demonstrated by selective precipitation of DNA fragments.     

钙激活钾通道在黎芦碱致神经细胞损伤中的作用

目的:观察新生SD大鼠原代培养皮层神经元的钙激活钾通道(Kca)在黎芦碱致神经元损伤模型上的激活、抑制效应.方法:采用细胞贴附和内面向外两种膜片钳单通道记录方法记录新生SD大鼠原代培养皮层神经元的Kca电生理活动.结果:黎芦碱在胞外可激活Kca.在有钙浴液内,细胞贴附式,钳制膜电位 30 mV,加入不同浓度黎芦碱(μmol/L:15、25、50、75),通道开放概率由0.005分别增加为0.014±0.003、0.085±0.010、0.132±0.016、0.059±0.006(P＜0.01),在50μmol/L以内表现出浓度依赖性.无钙浴液内,细胞贴附式膜片上,钳制膜电位 50 mV,随药物浓度(μmol/L)增加为15、40、60、100时,通道开放概率由0.005分别增加为0.014±0.010、0.113±0.006、0.141±0.004、0 295±0.009(P＜0.05).6例内面向外式膜片上,钳制膜电位 40 mV,分别加入黎芦碱25 μmol/L、50μmol/L 3 min后,通道开放概率由0.011±0.008分别增加为0.010±0.010、0.012±0.007(P＞0.05).黎芦碱在胞内Kca开放概率,平均开放/关闭时间,电流幅值均无明显变化.结论:黎芦碱通过影响胞内游离钙水平间接调节Kca,在缺血缺氧早期,胞内游离钙增高激活Kca开放.     

大鼠多囊卵巢颗粒细胞凋亡时MDA含量及SOD活性的变化

目的和方法以大鼠多囊卵巢（PCO）为动物模型,观察了PCO大鼠卵泡颗粒细胞凋亡的发生率,并检测了颗粒细胞凋亡时丙二醛（MDA）的含量及超氧化物歧化酶（SOD）活性的变化。结果①PCO颗粒细胞凋亡发生率明显高于正常（P<0．001）;②PCO颗粒细胞发生凋亡时,细胞内MDA含量增加而SOD活性降低。结论大鼠PCO颗粒细胞的凋亡可能与细胞内MDA含量增加和SOD活性降低有关。     

Modelling intravascular delivery from drug-eluting stents with biodurable coating: investigation of anisotropic vascular drug diffusivity and arterial drug distribution

In-stent restenosis occurs in coronary arteries after implantation of drug-eluting stents with non-uniform restenosis thickness distribution in the artery cross section. Knowledge of the spatio-temporal drug uptake in the arterial wall is useful for investigating restenosis growth but may often be very expensive/difficult to acquire experimentally. In this study, local delivery of a hydrophobic drug from a drug-eluting stent implanted in a coronary artery is mathematically modelled to investigate the drug release and spatio-temporal drug distribution in the arterial wall. The model integrates drug diffusion in the coating and drug diffusion with reversible binding in the arterial wall. The model is solved by the finite volume method for both high and low drug loadings relative to its solubility in the stent coating with varied isotropic–anisotropic vascular drug diffusivities. Drug release profiles in the coating are observed to depend not only on the coating drug diffusivity but also on the properties of the surrounding arterial wall. Time dependencies of the spatially averaged free- and bound-drug levels in the arterial wall on the coating and vascular drug diffusivities are discussed. Anisotropic vascular drug diffusivities result in slightly different average drug levels in the arterial wall but with very different spatial distributions. Higher circumferential vascular diffusivity results in more uniform drug loading in the upper layers and is potentially beneficial in reducing in-stent restenosis. An analytical expression is derived which can be used to determine regions in the arterial with higher free-drug concentration than bound-drug concentration.     

Plant regeneration via somatic embryogenesis of Elymus sibiricus cv. ‘chuancao No. 2’

The mature seeds, mesocotyls, and young leaf tips of Elymus sibiricus L. cv. ‘chuancao No. 2’ were cultured on Murashige and Skoog (MS) medium supplemented with 5.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-d) and 0.05 mg/L kinetin in the dark at 26°C, the calluses were produced. The rate of callus regeneration depended on the explants source and plant growth regulators. Plants regenerated from whitish-yellow-coloured compact nodular callus formed after subculturing for 8 weeks. Higher frequency (54%) of shoot differentiation was obtained from the embryo tissues of mature seed than from either mesocotyls (24%) or young leaf tip tissues (6%) when these calluses from different types of explants were cultured on plant regeneration medium containing half strength MS salts supplemented with 0.1 mg/L kinetin, 1.5 mg/L 2,4-D and 20 g/L sucrose. The green plants were rooted within 6 weeks in the root regeneration medium, and over 97% of these soil-established plants were obtained in the greenhouse when potted in a sand and peat mixture medium.     

中国大鲵研究进展

中国大鲵是我国特有濒危的两栖物种,是研究生物进化、生物多样性、性别决定分子机制等问题的好材料。近年来,人们对它的研究力度不断加大,著述颇多。本文对大鲵的生态保护、解剖发育、生理生化、遗传进化等方面的近期研究资料进行了整理和回顾,也简要探讨了今后大鲵研究的主要工作,以期为研究者们提供有价值的资料。     

生物转化生产D-塔格糖的食品级菌种选育及L-阿拉伯糖异构酶的克隆表达

L-阿拉伯糖异构酶(L-arabinose isomerase,L-AI)是一种可以催化D-半乳糖为D-塔格糖的胞内异构化酶。随着塔格糖在食品工业中越来越广泛的应用,能够将半乳糖转化为塔格糖的食品级微生物以及食品级来源的L-AI受到更大的关注。文中从各种酸奶制品、泡菜及其他一些食品中采集不同的样品,筛选出1株具有L-AI酶活的食品级菌株,经过生理生化鉴定以及16S rDNA序列测定,确定该菌株为戊糖片球菌,命名为Pediococcus pentosaceus PC-5。以该菌基因组为模板,克隆L-AI基因,并在大肠杆菌BL21成功地异源表达。表达产物经粗提取后,在40℃下加入Mn2+,使D-半乳糖转化为D-塔格糖的转化率为33%。     

Novel A14841G mutation is associated with high penetrance of LHON/C4171A family

We report the clinical and genetic characterization of a Chinese LHON family carrying an ND1/C4171A mutation. This family has high penetrance of visual impairment and extremely low frequency of vision recovery, which is in marked contrast to previously reported results for Korean LHON families with the same mutation. Sequence analysis of the complete mtDNA in the partially defined East Asian haplogroup N9a1 revealed the presence of 29 other variants. A novel heteroplasmic A14841G mutation, one of the variants with a serine substituted for a highly conserved asparagine at amino acid 32 of Cytochrome b (Cytb), may play a synergistic role with the C4171A mutation, leading to significantly different clinical manifestations of LHON among these families. The study further confirmed that C4171A was a rare primary LHON mutation, and the mtDNA background could also contribute to the clinical manifestation of the LHON/C4171A mutation.