气相爆轰波马赫反射的实验和数值研究

爆燃和爆轰是自然界中普遍存在的两种自然现象。在一定条件下爆燃完成向爆轰的转变，爆轰形成以后会出现典型的胞格结构，在爆轰波传播过程中遇到障碍物时会发生马赫反射。对这些现象的理论和实验研究在工程和科学上都有着重大的意义。在本文的实验研究中，采用爆轰激波管和烟熏膜技术对可燃气体DDT过程及爆轰波马赫反射问题进行了研究。在不同初压和楔角的情况下进行了系统的实验，得到了清晰的胞格结构图象和三波点轨迹图象。在本文的数值模拟中采用了简化的二阶段化学反应模型，整个化学反应过程被分为两个阶段：诱导反应阶段和放热反应阶段。该模型采用两个无量纲参数α和β来表示化学反应的进程。初始时刻两个参数值都为1，诱导反应开始时α的值由1逐渐减小到0，进入放热反应阶段β的值逐渐减小直到化学反应达到平衡。本文采用了全新的数值方法CE／SE对可燃气体的DDT过程和爆轰波马赫反射问题进行了数值模拟。CE／SE方法是一种在概念和方法上都和以往不同的数值方法。该方法具有构造简单、分辨率高等优点，同时格式保证了在局部和全局均满足时空意义上的守恒律。本文的研究结果表明：爆轰波遇到楔面会发生类似冲击波的正规反射和马赫反射现象。在不同楔角和初压条件下，反射前后爆轰波的胞格尺寸、形状等性质都会有明显的差别。同时三波点迹线与楔面的夹角也会有相应的变化。这些结果对于深入理解可燃气体的DDT过程和爆轰波的马赫反应射机理有重要价值。最后需要提出的是我们把全新的CE／SE方法推广到带有化学反应的流动计算中，计算结果表明这种推广是成功的。

Efeitos pleiotrópicos da telmisartana nos tecidos adiposos branco e marrom: aumento da expressão gênica e proteica pan-PPAR em camundongos obesos

Receptores ativadores de proliferação perixossomal(PPARs) são fatores de transcrição envolvidos com a oxidação dos ácidos graxos e proliferação celular, mediando diversas vias, o que representa uma estratégia promissora para enfrentar as características da síndrome metabólica. Existem três isoformas de PPARs(PPARalfa, beta/delta e gama), que são diferencialmente expressos em diferentes tecidos.No presente estudo, objetivou-se avaliar os efeitos pleiotrópicos da telmisartana, um anti-hipertensivo, bloqueador do receptor AT1 da angiotensina e agonista parcial PPAR gama, no tecido adiposo branco (TAB) e marrom (TAM) em camundongos obesos induzido por dieta.Camundongos machos, da linhagem C57BL/6 foram alimentados com uma dieta padrão (standard-chow, 10% da energia proveniente de lipídios) ou com uma dieta com alto teor lipídico (high fat, 49% de energia proveniente de lipídios) durante 10 semanas. Em seguida, os animais foram distribuídos aleatoriamente em quatro grupos: SC, SC-T, HF e HF-T (n=10). O fármaco foi administrado (10mg/kg de dieta) durante 4 semanas para os grupos SC-T e HF-T.O grupo HF apresentou sobrepeso, hipertensão arterial sistêmica, perfil de adipocinas pró-inflamatórias, resistência insulínica, diminuição do gasto energético, comprometimento do metabolismo da glicose e distribuição anormal da massa adiposa. Além disso, a obesidade ocasionou diminuição da expressão de PPARalfa, beta/delta e gama noTAB e TAM, resultando na inadequação da captação de glicose e termogênese insuficiente. Por outro lado,a ativação das três isoformas de PPARs, a melhora do perfil inflamatório das adipocinas, o aumento da sensibilidade à insulina e a melhora da captação de glicose, foi vistaapós o tratamento com telmisartana. A ativação dos PPARs no TAB trouxe muitos benefícios. No TAM, resultados surpreendentes foram que a telmisartana provocou o aumento da expressão do recepetor adrenérgico beta 3 (RAβ3), induzido pela ativação de PPARbeta/delta e maior termogênese comaumento da expressão da proteína desacopladora1 (UCP1). Em conclusão, nossos resultados mostram que telmisartanaaumenta a expressão gênica e proteica PAN-PPAR no TAB e TAM em camundongos obesos induzidos por dieta. Nossas observações mostram que, apesar do grupo HF-T ter reduzido a ingestão energética, os efeitossão explicados pela ativação PAN-PPAR da telmisartana, causando a ativação da termogênese e resultando num balanço energético negativo.

四个烙铁头蛇毒凝集素样蛋白基因的克隆与序列分析

从烙铁头蛇（Trimeresurus mucrosquamatus）的毒腺中提取mRNA，利用RT-PCR进行体外扩增，获得凝集素样蛋白基因，克隆至PMD18-T载体中，筛选出4种凝集素样蛋白基因（命名为TML-1、TML-2、TML-3和TML-4）。由基因序列推导出的氨基酸序列表明：TML-1，2，3，4序列中均有CRD结构。序列同源性比较和Cys位点分析推测：TML-1和TML-2可能分别是类似于flavocetin-A的蛇毒凝集素样蛋白的#alpha#亚基和#beta#亚基；TML-3可能类似于GPIb-bp的蛇毒凝集素样蛋白的#alpha#亚基，TML-4则可能是类似于IX/X-bp的蛇毒凝集素样蛋白的β亚基。

蛋白质序列和结构的保守性与其功能的关系

在酪氨酸磷酸酶超家族分子的序列中,仅有3个与其催化功能密切相关的残基是高度保守的,但它们功能结构域的核心拓扑结构却明显类似,其中存在着#beta##alpha##beta#和#beta##alpha##beta##alpha#2个保守的结构单元;此外,它们活性位点的拓扑结构也极其相似。

Chronic Morphine Treatment Impaired Hippocampal Long-Term Potentiation and Spatial Memory via Accumulation of Extracellular Adenosine Acting on Adenosine A(1) Receptors

Chronic exposure to opiates impairs hippocampal long-term potentiation (LTP) and spatial memory, but the underlying mechanisms remain to be elucidated. Given the well known effects of adenosine, an important neuromodulator, on hippocampal neuronal excitability and synaptic plasticity, we investigated the potential effect of changes in adenosine concentrations on chronic morphine treatment-induced impairment of hippocampal CA1 LTP and spatial memory. We found that chronic treatment in mice with either increasing doses (20-100 mg/kg) of morphine for 7 d or equal daily dose (20 mg/kg) of morphine for 12 d led to a significant increase of hippocampal extracellular adenosine concentrations. Importantly, we found that accumulated adenosine contributed to the inhibition of the hippocampal CA1 LTP and impairment of spatial memory retrieval measured in the Morris water maze. Adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine significantly reversed chronic morphine-induced impairment of hippocampal CA1 LTP and spatial memory. Likewise, adenosine deaminase, which converts adenosine into the inactive metabolite inosine, restored impaired hippocampal CA1 LTP. We further found that adenosine accumulation was attributable to the alteration of adenosine uptake but not adenosine metabolisms. Bidirectional nucleoside transporters (ENT2) appeared to play a key role in the reduction of adenosine uptake. Changes in PKC-alpha/beta activity were correlated with the attenuation of the ENT2 function in the short-term (2 h) but not in the long-term (7 d) period after the termination of morphine treatment. This study reveals a potential mechanism by which chronic exposure to morphine leads to impairment of both hippocampal LTP and spatial memory.

湖南尖吻蝮蛇毒出血毒素的圆二色性和化学修饰

用远紫外CD谱研究了湖南产尖吻蝮蛇毒的两个出血毒素(DaHT-1、DaHT-2)的溶液构象, 计算得DaHT-1的#alpha#螺旋、#beta#折叠、无规卷曲的含量分别为36.9%, 35.5%, 27.6%; DaHT-2的#alpha#螺旋、#beta#折叠、无规卷曲分别为23.4%, 31.3%, 45.3%。随pH的增大或减小。温度和pH对CD谱的影响相似。0.02mol/L EDTA便导致两个出血毒素呈极度的无序状态。胰蛋白酶不影响它们的出血活性。图4表4参10

人精子抗原决定簇的末端单糖参与小鼠IgA单抗与抗原的结合

对消化道免疫获得的33个抗精子IgA单抗, 12个IgG和35个IgM单抗靶抗原的生化性质及末端单糖做了鉴定。免疫印迹的结果显示, IgA、IgG和IgM类单抗靶抗原的分子量范围分别为10-89、11-75和12-94KDa。有12个单抗的靶抗原为非蛋白类的糖复合物, 一个IgA单抗(A22)的靶抗原为不含糖的蛋白。凝集素封闭和糖苷酶消化试验的结果显示, 98.7%单抗的靶抗原分子末端含一种或几种糖。五种凝集素对IgA类单抗靶抗原的抗原的封闭效应均较强, 表明IgA类单抗靶抗原的抗原决定簇含有岩藻糖、乙酰氨基葡萄糖、乙酰氨基半乳糖、半乳糖和甘露糖等末端单糖者较多。IgG类单抗靶抗原的抗原决定簇则含有带岩藻糖、乙酰氨基半乳糖和#alpha#-甘露糖等末端单糖者较多。内切-#beta#-半乳糖苷酶消化试验的结果表明, 54.4%IgA类单抗的靶抗原为依赖半乳糖苷连接的糖肽化合物。这些结果表明, 经消化道免疫能产生IgA及其它类别抗体的绝大多数人精子抗原为含多种类型末端单糖的膜表面分子。

尖吻蝮蛇蛇毒出血毒素DaHT-3的纯化与性质

通过Sephadex G-75,DEAE-Sephadex A-50,Sephadex G-200和两次PBE聚焦层析,从尖吻蝮蛇(Dienagkistrodon acutus)蛇毒中纯化到一个分子量为56 000的出血毒素(DaHT-3),经氨基酸组成测定计算,由487个氨基酸残基组成。此成分在SDS-PAGE上显示出一条均一的蛋白染色带,用等电聚焦电泳测定,其pI为5.50。该出血成分的最小出血剂量是2.6#mu#g,具有蛋白水解酶活力,其活力为3.68,但没有精氨酸酯酶和磷脂酶A_(2)活力。用红外光谱仪研究DaHT-3在溶液中酰胺Ⅰ带的吸收谱,该毒素含有31.8%的#alpha#螺旋、56.1%的#beta#折叠和12.1%的转角;当加入EDTA螯合剂去除金属离子后,它们的#alpha#螺旋、#beta#折叠、转角和无规卷曲分别变为11%、26.4%、46.2%和16.5%,而出血活力和蛋白水解酶活力均丧失,表明该出血毒素是金属蛋白酶。

人基因中密码子前后碱基使用与蛋白质结构

对62个人基因中编码蛋白质各类二级结构(#alpha#-螺旋、#beta#-折叠片、无规卷曲和回折)的密码子前后碱基的使用情况进行统计分析和比较,发现多数密码子前后碱基的使用有一定偏向,而且这些偏向与蛋白质的二级结构有关联。这同时亦提示,同义密码子的选用与蛋白质的二级结构有一些关联。结果对于蛋白质结构预测算法以及基因工程的研究有辅助作用。

大肠杆菌基因中密码子前后碱基的使用与蛋白质结构

对一组E. coli基因中编码蛋白质各类二级结构(#alpha#-螺旋、#beta#-折叠片、无规卷曲和回折)的密码子前后碱基的使用情况进行统计分析和比较,发现一些密码子前后碱基的使用有偏向,而且这些偏向与蛋白质的二级结构有关联。这同时亦表明,E. coli基因中同义密码子的选用与蛋白质的二级结构有一些关联。模型对于蛋白质结构预测算法的改进以及基因工程的研究有辅助作用。

鲤鱼发育早期HPG轴和GH/IGF轴相关因子的转录起始分析

采用RT-PCR的方法,以不同发育时期的鲤鱼胚胎和幼鱼为材料,研究了与鱼类生殖相关的HPG轴以及与生长相关的GH/IGF轴中GnRH、GtH以及GH、GHR和IGF重要信号分子的转录起始特征。结果显示,sGnRH、cGnRH、GtH-Iβ亚基和GHR于鲤鱼胚胎受精后20h开始转录,IGF-1于受精后23h开始转录,GtH-IIβ亚基于受精后26h开始转录,GtHα亚基于受精后46h开始转录,GH于1dph(孵出后第1天)开始转录。其中,GHR和IGF-1均早于GH开始转录,GtHα亚基和β亚基的转录起始时

鲫鱼囊胚细胞干扰素的诱导及部分特性

用紫外线灭活的草鱼呼肠孤病毒 (GCRV)诱导鲫鱼囊胚细胞 (CAB)能产生一种高滴度的抗病毒物质。这种物质在 5 6℃及 pH 2～ 11稳定 ;对胰蛋白酶敏感 ;抗病毒活性受被保护细胞的密度、培养温度及保护时间的影响 ;不能被GCRV的特异性抗体中和 ;无直接杀病毒作用 ;抗病毒机制依赖于细胞内RNA和蛋白质的合成 ;在多种鱼类培养细胞中具有抑制病毒作用。这些特性与哺乳类α/ β干扰素一致 ,是一种鲫鱼干扰素

对-氯代苯胺(PCA)在填充床生物反应器中的降解作用

以氯代苯胺（ＰＣＡ）为选择基质，用驯化技术从降解对二氯苯（ｐＤＣＢ）的富集培养物中得到了以同化ＰＣＡ为唯一碳源和氮源的混合微生物．将这种固定在填充床反应器中的微生物用于ＰＣＡ的降解作用研究中．在该反应器里，ＰＣＡ的生物降解遵循Ｌｏｇｉｓｔｉｃ方程ｑ＝ｑｍａｘ／（１＋ｅα－βＵｖ）．由方程求出了主要的动力学常数，Ｋｓ（半速率常数）和ｑｍａｘ（最大比基质降解速率）．于ＰＣＡ降解的同时，释放氯离子到培养基中．在水力停留时间３ｈ，进水ＰＣＡ浓度为３６０ｍｇ·Ｌ－１情况下，基质的体积降解率达到１２５ｍｇ·Ｌ－１

Cytotoxicity evaluation of three pairs of hexabromocyclododecane (HBCD) enantiomers on Hep G2 cell

Hexabromocyclododecanes (HBCDs) are additive brominated flame retardants mainly used in plastics and textiles. At the present time, these compounds are found in almost all environmental and human samples. In order to evaluate the environmental safety and health risk of HBCDs, the enantiomerically pure alpha-, beta-, and gamma-HBCD were prepared using high performance liquid chromatography (HPLC) on a PM-P-CD column and the cytotoxicities of their enantiomers were evaluated in Hep G2 cells. Results from the 3-(4,5-dimethylthioazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), resazurin reduction and lactate dehydrogenase (LDH) release assays showed a good agreement that the order of cytotoxicity was gamma-HBCD >= beta-HBCD > alpha-HBCD, and that significantly lower cell viability and higher LDH release were observed in all (+)-enantiomers ((+) alpha-, (+) beta- and (+) gamma-HBCD) than the corresponding (-)-forms ((-) alpha-, (-) beta- and (-) gamma-HBCD). Additionally, the formation of reactive oxygen species (ROS) induced by these HBCD enantiomers were detected. The positive correlation between the LDH release and ROS formation demonstrated that the toxic mechanism might be mediated by oxidative damage. These results suggest that environmental and human health risks of HBCDs must be evaluated at the level of individual enantiomers. (C) 2008 Published by Elsevier Ltd.

黄土丘陵沟壑区坡沟植被生态序列研究

植被生态序列是小地形对植被空间分布影响的反映。采用样线法,对安塞纸坊沟支沟拐沟中南北向短坡面深沟谷和长坡面浅沟谷断面进行植被调查,分析其植被生态序列特征、物种组成及物种多样性。结果表明:短坡面深沟谷序列主要以灌乔木等演替后期物种为主,而长坡面浅沟谷序列则主要为草本物种;同一序列中,阴坡、沟谷地具有比阳坡、沟间地复杂的演替后期群落;序列中物种主要由菊科(Compositae)、豆科(Leguminoseae)和禾本科(Gramineae)构成,生活型主要为多年生草本,生态型以旱生、中旱生为主。α多样性指数在阴坡和短坡面深沟谷序列较高,β多样性指数在地形变化活跃的沟缘线区较高。研究结果可为黄土丘陵沟壑区植被建设人工调节提供参考依据。