Stem cells in development of therapeutics for Parkinson's disease: a perspective

Using Parkinson's disease as a prototype of neurodegenerative diseases, we propose applications of human stem cells in the development of therapeutics for neurodegenerative diseases. First, in vitro differentiation of human stem cells offers a versatile model for dissecting molecular interactions underlying human dopamine (DA) neuron specification, which may form a foundation for instigating regeneration of DA neurons from progenitors that reside in the brain. Second, stem cells derived from diseased cells or through genetic modification can serve as a platform for unraveling biochemical processes that lead to the cellular pathogenesis of degeneration. This may in turn serve as a template for identifying or developing therapeutics for slowing, stopping, or reversing the disease process. And finally, stem cells, particularly those induced from patients' own cells, provide a reliable source of DA neurons for cell-based therapy.     

贵州黔西县少数民族ABO血型分布及基因频率调查

对贵州黔西县1260例6个少数民族人群红细胞ABO表现型进行了检测;结果如下:贵州黔西县布依族、满族、苗族、白族这四个民族的ABO血型基因频率很相近,彝族和仡佬族与这4个民族的差别较大,布依族,苗族,满族,白族ABO血型分布为O>B>A>AB,彝族为O>A>B>AB,仡佬族为A>O>B>AB;经Hardy Weinberg吻合度检测可以证明贵州黔西县的ABO血型表现型分布状况及基因频率相对稳定,其分布符合hardy Weinberg平衡,获得了该地ABO血型系统群体遗传学数据,为群体遗传学的研究提供了一定的资料。     

腺病毒介导的uPAR反义核酸转移抑制肿瘤细胞的侵袭

为了观察尿激酶受体(uPAR)反义核酸对肿瘤细胞体外侵袭的抑制作用,用PCR方法扩增uPAR cDNA 5′端－46 bp～＋454 bp一段长500 bp的序列,利用DNA重组技术将其克隆到病毒载体pAdeno-X中, 构建出重组腺病毒载体pAdeno-X-uPAR(－)和pAdeno-X-uPAR(+).线性化后的重组腺病毒载体转染HEK293细胞7天后,可以获得滴度分别为1.5×10⁸ pfu/ml和0.5×10⁸ pfu/ml的uPAR反义和正义核酸表达重组腺病毒,分别命名为Ad-uPAR(－)和Ad-uPAR(+).以不同的病毒感染指数（MOI）感染人肺巨细胞癌高转移株95D肿瘤细胞,3天后用RNA印迹法可以检测肿瘤细胞uPAR正义和反义核酸表达水平,随着MOI的升高,Ad-uPAR(－)感染的肿瘤细胞uPAR蛋白水平逐渐下降,肿瘤细胞的体外侵袭能力也明显下降,而感染Ad-uPAR(+)的肿瘤细胞无明显变化.结果表明,重组腺病毒可以表达uPAR正义和反义核酸,uPAR反义核酸可以明显抑制人肺巨细胞癌高转移株95D肿瘤细胞在体外的侵袭能力.     

不同烟草品种叶下表皮微形态学特征的研究

利用扫描电镜及光学显微镜对烤烟、晒烟及野生烟共29个品种叶下表皮微形态学特征进行了观察,发现相同类型的烟草品种间表现出一些共同特征,但不同类型的烟草品种间其叶下表皮微形态学特征又存在一定的差异。烤烟气孔外拱盖内缘较丰富,晒烟次之,野生烟在所观察的品种中只有1种类型;烤烟气孔密度和长度的变幅比较大,晒烟则比较稳定;烤烟、晒烟细胞间多有突起,保卫细胞极区常见“T”型加厚,绝大多数有角质环边;而所观察的两个野生烟品种均无细胞间突起,无保卫细胞极区加厚,亦无角质环边。这些观察结果为烟草分类研究提供了有价值的参考依据。同时本文还探讨了烟草亲本与子代之间在叶下表皮微形态学特征上的关联性。     

香溪河流域一条一级支流河岸林凋落物季节动态

对神农架南坡的一条一级支流河岸林的凋落物进行了一年的连续收集研究。结果表明：凋落物干重年输入量为438．72g／m^2,其中树叶凋落物是凋落物的主要成分,占整个凋落物年产量的84％。凋落物的输入明显存在季节性的时间格局。凋落物在秋季的产量占全年产量的75％,春季占6．2％,夏季占13．6％,冬季为5．5％。凋落物组成中,树叶和花果的产量显示出季节变化的趋势;枝条的产量并未显示出明显的季节趋势。在秋季,树叶的产量占全年树叶总量的83％;枝条最高值出现于秋季,产量占全年总员的29％;花果在整个凋落物中所占比重分小,最高值出现在夏季,占年产量的63％。着生藻类的密度月际间的变化较大,存在着显著的差异。最大值与最小值的出现月份与凋落物最大、最低值的出现月份相同。通过统计分析表明,着生藻类的密度变化与凋落物和树叶凋落物的动态具有明显的相关性。     

维生素C对视网膜色素上皮蓝光损伤保护作用的研究(简报)

维生素C为6碳多羟化合物,在化学反应中易失去电子,依次生成半脱氧抗坏血酸和脱氧抗坏血酸。因此,维生素C可作为自由基清除剂,能迅速与超氧阴离子、氢化氧基、过氧化氢、羟自由基反应,生成抗坏血酸自由基。蓝光作为一种短波长,靠近紫外线频段的光,具有能量高的特点,是自然界中导致视网膜色素上皮细胞损伤甚至凋亡的主要光线。本实验通过观察蓝光照射视网膜色素上皮,对其DNA的损伤产生光损伤作用,并比较加入维生素C后对这种光损伤的保护作用,以期探讨维生素C在     

Cyclooxygenase expression is elevated in retinoic acid-differentiated U937 cells

Cyclooxygenase (COX) is the rate-limiting enzyme for the biosynthesis of prostaglandins in monocytes/macrophages. The COX-1 is constitutively expressed in most tissues and may be involved in cellular homeostasis, whereas the COX-2 is an inducible enzyme that may play an important role in inflammation and mitogenesis. When U937 monocytic cells were incubated with retinoic acid (RA) for 48 h, cell differentiation took place with concomitant increases in prostaglandin E₂ (PGE₂) production and COX activity. In this study, the mechanism of RA (all-trans- or 9-cis-RA)-induced enhancement of PGE₂ biosynthesis in U937 cells was examined. Treatment of cells with all-trans- or 9-cis-RA up to 48 h caused an increase in PGE₂ production in a time- and dose-dependent manner. Both RA isomers caused the enhancement of PGE₂ production and the up-regulation of COX-1 expression at the protein and mRNA levels. The increase in COX-1 mRNA was found to precede the increase in COX-1 protein expression. Interestingly, the COX-2 protein and COX-2 mRNA were not detected in U937 cells, and their levels remained undetectable during the entire course of RA treatment. We conclude that treatment of U937 cells by RA for 48 h caused the initiation of cell differentiation, which was found to be concomitant with a significant increase in PGE₂ production mediated via the up-regulation of COX-1 mRNA and protein expression.     

Characterization of the G‐quadruplex structure of a catalytic DNA with peroxidase activity

It has been reported that the complexes formed by hemin and some G‐quadruplexes can be developed as a new class of DNAzyme with peroxidase activity. This kind of DNAzyme has received a great deal of attention. But to date, the actual G‐quadruplex structure that can provide hemin with enhanced peroxidase activity is in doubt. Herein, the G‐quadruplex structure of CatG4, a 21‐nucleotide DNA oligomer which was previously reported to bind hemin and the resulting complex exhibiting enhanced peroxidase activity, was characterized by fluorescence and circular dichroism measurements. The results suggest that the catalytically active form of CatG4 may be a unimolecular parallel quadruplex rather than a unimolecular chair‐type antiparallel quadruplex or a multistranded parallel quadruplex. In addition, the fluorescence analysis of labeled oligonucleotides may be developed as a supplementary tool for the study of DNA conformations. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 331–339, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

A mild, efficient, and selective procedure for transprotection of acetonides to acetates catalyzed with HClO4-SiO2

The transformation of acetonides into acetates is frequently required in synthetic chemistry. An efficient procedure for direct conversion of acetonides into acetates in the presence of HClO₄-SiO₂ under mild conditions was developed. The acetonides of primary hydroxy groups are directly converted to diacetates, and the anomeric acetonides of furanosides are stereoselectively transformed into the corresponding acetyl β-d-furanosides with a 2-acetoxyisopropyl group.