Synthesis and evaluation of (S,S)-N,N′-bis-[3-(2,2′,6,6′-tetramethylbenzhydryloxy)-2-hydroxy-propyl]-ethylenediamine (S2824) analogs with anti-tuberculosis activity

In order to identify new and potent candidate drugs to treat tuberculosis, a library of compounds was screened, and (S,S)-N,N′-bis-[3-(2,2′,6,6′-tetramethylbenzhydryloxy)-2-hydroxy-propyl]-ethylenediamine (S2824) was identified as a hit in the screen. This research discusses our efforts to synthesize and test 30 analogs of this hit for activity against Mycobacterium tuberculosis. Two compounds with homopiperazine ring possess high in vitro activity against drug sensitive and resistant M. tuberculosis with MICs 0.78–3.13 μg/mL (or 1.22–4.88 μM).     

全球结核病疫苗研究进展

本文旨在对全球结核病疫苗研究进展进行系统综述,描述国际上目前进入临床试验不同阶段的新型疫苗,包括重组卡介苗、亚单位疫苗、治疗性疫苗等,分析我国结核病疫苗研究现状,介绍国际研究发展趋势,如人类疫苗计划、全细胞疫苗、多阶段疫苗等,并对存在的问题和挑战进行讨论,展望未来发展趋势。     

Sex‐ and age‐related differences in c‐fos expression in dog olfactory bulbs

Sex‐ and age‐related differences in cognitive abilities are frequently reported. However, the sex‐ and age‐related differences in dog olfaction due to biological system are still poorly understood. We examined c‐fos expression in dog olfactory bulbs by immunohistochemistry approaches. The c‐fos is mainly expressed in the olfactory glomerular layer (GL), mitral cell layer (ML) and granule cell layer (GRL). We found that a higher density of c‐fos‐positive cells could be detected in the ML of olfactory bulbs of adult female dogs compared with that in males and the c‐fos‐positive cells in females' olfactory bulbs are more distinct. Sex‐related differences in c‐fos expression also appeared in the GL of olfactory bulbs in juvenile dogs. We also discovered that the density of c‐fos‐positive cells in the GRL of adult dogs was much higher than that in the GRL of juvenile dogs. Our results indicate that cells in the olfactory bulbs of female dogs are more active than those in males and female dogs may have much stronger ability for long‐time memory of odours than male dogs. Furthermore, our results also suggest that adult dogs may have much stronger ability for long‐time memory of odours and can deal with more complicated odour information than juvenile dogs.     

Exploring<Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis> infection-induced alterations in gene expression in macrophage by microarray hybridization

Tuberculosis remains a serious threat to public health. Its causative agentMycobacterium tuberculosis is an intracellular pathogen which survives and replicates within cells of the host immune system, primarily macrophages. Knowledge of the bacteria-macrophage interaction can help to develop novel measures to combat the disease. The global gene expression of macrophage following invasion by and growth ofM. tuberculosis was studied by cDNA microarray. Of the 12800 human genes analyzed, totally 473 (3.7%) macrophage genes were differentially expressed after being infected byM. tuberculosis, among which, only 25 (5.2%, corresponding to less than 0.2% of the 12800 genes) genes were up-regulated, while others (94.8%) were down-regulated against the control. Of the 473 genes, 376 genes are registered in the GenBank, and 97 are novel genes. Expression of 5 up-regulated genes has been induced by more than 3-fold. 25 genes were down-regulated by more than 3-fold. Syndecan binding protein has been down-regu- lated up to 12.5-fold. The data gave an insight into the early gene expression in macrophage ensuingM. tuberculosis infection and a basis for further study.     

Protein kinase B and extracellular signal‐regulated kinase contribute to the chondroprotective effect of morroniside on osteoarthritis chondrocytes

Despite extensive studies on the multifaceted roles of morroniside, the main active constituent of iridoid glycoside from Corni Fructus, the effect of morroniside on osteoarthritis (OA) chondrocytes remains poorly understood. Here, we investigated the influence of morroniside on cultured human OA chondrocytes and a rat experimental model of OA. The results showed that morroniside enhanced the cell viability and the levels of proliferating cell nuclear antigen expression (PCNA), type II collagen and aggrecan in human OA chondrocytes, indicating that morroniside promoted chondrocyte survival and matrix synthesis. Furthermore, different doses of morroniside activated protein kinase B (AKT) and extracellular signal‐regulated kinase (ERK) in human OA chondrocytes, and in turn, triggered AKT/S6 and ERK/P70S6K/S6 pathway, respectively. The PI3K/AKT inhibitor LY294002 or the MEK/ERK inhibitor U0126 attenuated the effect of morroniside on human OA chondrocytes, indicating that the activation of AKT and ERK contributed to the regulation of morroniside in human OA chondrocytes. In addition, the intra‐articular injection of morroniside elevated the level of proteoglycans in cartilage matrix and the thickness of articular cartilage in a rat experimental model of OA, with the increase of AKT and ERK activation. As a consequence, morroniside has chondroprotective effect on OA chondrocytes, and may have the therapeutic potential for OA treatment.     

Biosynthesis of isoprenoids: characterization of a functionally active recombinant 2-C-methyl-D-erythritol 4-phosphate cytidyltransferase (IspD) from Mycobacterium tuberculosis H37Rv

Tuberculosis, caused by Mycobacterium tuberculosis, continues to be one of the leading infectious diseases to humans. It is urgent to discover novel drug targets for the development of antitubercular agents. The 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway for isoprenoid biosynthesis has been considered as an attractive target for the discovery of novel antibiotics for its essentiality in bacteria and absence in mammals. MEP cytidyltransferase (IspD), the third-step enzyme of the pathway, catalyzes MEP and CTP to form 4-diphosphocytidyl-2-C-methylerythritol (CDP-ME) and PPi. In the work, ispD gene from M. tuberculosis H37Rv (MtIspD) was cloned and expressed. With N-terminal fusion of a histidine-tagged sequence, MtIspD could be purified to homogeneity by one-step nickel affinity chromatography. MtIspD exists as a homodimer with an apparent molecular mass of 52 kDa. Enzyme property analysis revealed that MtIspD has high specificity for pyrimidine bases and narrow divalent cation requirements, with maximal activity found in the presence of CTP and Mg(2+). The turnover number of MtIspD is 3.4 s(-1). The Km for MEP and CTP are 43 and 92 muM, respectively. Furthermore, MtIspD shows thermal instable above 50 degrees C. Circular dichroism spectra revealed that the alteration of tertiary conformation is closely related with sharp loss of enzyme activity at higher temperature. This study is expected to help better understand the features of IspD and provide useful information for the development of novel antibiotics to treat M. tuberculosis.     

Lesion recognition and cleavage by endonuclease V: a single-molecule study

Endonuclease V (endo V) recognizes and cleaves deoxyinosine in deaminated DNA. These enzymatic activities are precursors of DNA repair and are fueled by metal ions such as Ca2+ and Mg2+, with the former being associated with protein binding and the latter with DNA cleavage. Using the technique of fluorescence resonance energy transfer (FRET), we determined the single-molecule kinetics of endo V in a catalytic cycle using a substrate of deoxyinosine-containing single-stranded DNA (ssDNA). The ssDNA was labeled with TAMRA, a fluorescence donor, while the endo V was labeled with Cy5, a fluorescence acceptor. The time lapses of FRET, resulting from the sequential association, recognition, and dissociation of the deoxyinosine by the endo V, were determined at 5.9, 14.5, and 9.1 s, respectively, in the presence of Mg2+. In contrast, the process of deoxyinosine recognition appeared little affected by the metal type. The prolonged association and dissociation events in the presence of the Ca2+-Mg2+ combination, as compared to that of Mg2+ alone, support the hypothesis that endo V has two metal binding sites to regulate its enzymatic activities.     

内蒙古东部草原地区赤狐繁殖期对洞穴的选择

通过对内蒙古东部草原地区赤狐的２５个洞穴观测,运用系统聚类分析的方法,研究了赤狐繁殖期的洞穴选择。结果表明,影响赤狐繁殖期洞穴选择的主要因子是水源,其次是坡向、坡位和坡度,人为干扰、隐蔽程度及洞口朝向等因子对其影响作用不明显。繁殖期赤狐的最适洞穴选择为：阳坡或半阴半阳坡、下坡位、坡度５°～２５°、距水源５００～１０００ｍ。     

中国狼不同地理种群遗传多样性及系统进化分析

为了解中国狼不同地理种群遗传多样性及系统发育情况,从中国境内狼的主要分布区青海、新疆、内蒙古和吉林4个地区采集样品,用分子生物学技术手段成功地获得44个个体线粒体DNA控制区第一高变区(HVRⅠ)序列和40个线粒体Cyt b部分序列。线粒体控制区HVRⅠ共检测到51个变异位点,位点变异率为8.76%;线粒体Cyt b部分序列发现31个变异位点,位点变异率为5.33%,未见插入及缺失现象,变异类型全部为碱基置换。共定义了16个线粒体HVRⅠ单倍型,其中吉林与内蒙种群存在共享单倍型,估计这两地间种群亲缘关系较近。4个地理种群中新疆种群拥有较高的遗传多样性(0.94)。中国狼种群总体平均核苷酸多态性为2.27%,与世界其他国家地区相比,中国狼种群拥有相对较高的遗传多样性。通过线粒体HVRⅠ单倍型构建的系统进化树可以看出,中国狼在进化上分为2大支,其中位于青藏高原的青海种群独立为一支,推测其可能长期作为独立种群进化。基于青海种群与新疆,内蒙种群的线粒体Cyt b遗传距离,推测中国狼2个世系可能在更新世冰川时期青藏高原受地质作用急速隆起后出现分歧,分歧时间大约在1.1 MY前。