急性低氧对大鼠微血管反应性及抗氧化酶的影响

目的：探讨不同急性低氧条件下对肠系膜微动脉血管反应性和抗氧化酶的影响。方法：实验采用给予大鼠吸入含氧量为12．5％和8．5％的氮氧混合气体,观察急性低氧后肠系膜微动脉血管口径、血流速度和血中谷光甘肽过氧化物酶（GSH—PX）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和活性氧（ROS）含量的变化。结果：肠系膜微动脉血管口径随急性低氧时间延长而逐渐增大,而血液流速却减慢（P〈0．01,P〈0．05）;SOD、CAT和GSH—PX活力明显下降,ROS含量增加（P〈0.01,P〈0．05）。结论：急性低氧可使肠系膜微动脉管径变大和血液流速减慢;同时体内抗氧化酶活性减弱,这可能与自由基产生增加有关。     

低氧反应和屏气反应在急性高原反应预测中的作用

目的:探讨低氧反应和屏气反应在急性高原反应预测中的作用.方法:在平原观察113名入藏人员吸入10%低氧气体10 min和屏气过程中的血氧饱和度、心率和血压变化;进入高原后进行急性高原反应(AMS)症状评分;两组数据进行相关分析,并对急性高原反应者和基本无反应者数据进行分析.结果:吸入10%低氧气体过程中,动脉血氧饱和度进行性下降,心率迅速升高,血压普遍呈现先升高后降低的变化趋势.急性高原反应者吸入低氧气体1min时的心率明显慢于基本无反应者.所观测指标均存在着较大的个体差异,但相关分析表明,AMS评分仅与吸入低氧气体7 min时的心率呈显著负相关,相关系数r为-0.176.结论:在平原单纯用低氧和屏气反应来预测3 658 m高原地区的AMS发病情况意义可能有限.     

内皮素-1预处理对培养乳鼠心肌细胞低氧损伤的保护作用

实验观察了 0 0 1- 1nmol/L内皮素 1(ET 1)预处理对低氧孵育 ( 3 %O2 5 %CO2 ,12h)的培养乳鼠心肌细胞乳酸脱氢酶 (LDH)释放量、培养液上清超氧化物歧化酶 (SOD)活性以及丙二醛 (MDA)含量的影响。用Fluo 3 /AM负载培养的心肌细胞 ,在激光扫描共聚焦显微镜下监测急性低氧的心肌细胞 [Ca2 +]i 的变化和ET 1预处理对低氧所致 [Ca2 +]i 变化的影响。结果如下 :( 1)心肌细胞低氧孵育 12h后 ,培养液上清LDH活力和MDA含量较常氧对照组明显升高 ,分别为 43 3 3± 1 2 1U/Lvs 19 3 3± 1 0 3U/L和 1 71± 0 0 2nmol/Lvs 0 91± 0 0 3nmol/L (P<0 0 1) ,SOD活性为 16 93± 1 11U/ml明显低于常氧对照组的 3 3 48± 1 15U/ml (P <0 0 1) ;0 0 1- 1nmol/LET 1预处理呈浓度依赖性抑制低氧培养心肌细胞LDH释放 ,减少培养液上清MDA含量、提高SOD活性 (P <0 0 1)。 ( 2 )低氧灌流后 2 9± 1 5s (n =2 3 )心肌细胞自发性钙瞬变完全终止 ,[Ca2 +]i 升高了 10 7± 13 2 % (P <0 0 0 1) ;0 0 1- 1nmol/LET 1能明显加快心肌细胞钙瞬变的频率 (P <0 0 1) ;ET 1预处理后低氧所致钙瞬变终止的时间较单纯低氧组明显推迟 ,[Ca2 +]i过度升高被明显减轻 (P <0 0 1)。上述结果表明 ,0 0 1- 1nmol/LET 1预处理可减轻培     

急性低温复合低氧对正常家兔、心肌缺血家兔SOD和MDA的影响

目的:探讨急性低温低氧两种因素对正常和心肌缺血家兔SOD、MDA同时作用的影响.方法:将正常和心肌缺血家兔置于低温(-10±2℃)和低氧(氧含量为 8.5% )冷柜中1 h,测定血清中SOD活力和MDA含量.结果:急性低温低氧后,血清中SOD显著降低(P＜0.01),MDA明显升高(P＜0.05).结论:急性低温低氧有加重机体的损伤作用.     

G_(i/o)蛋白介导的信息转导通路在低氧预处理心肌保护中的作用

实验以低氧 3h后复氧期间心肌细胞的生存率和LDH的释放量为指标 ,观察Gi/o蛋白及其下游成分在低氧预处理 (hypoxicpreconditioning ,HP)心肌保护中的作用。与单纯低氧组相比 ,HP组 ( 2 5min低氧 30min复氧作为HP)细胞生存率增高 ,LDH释放减少 (P <0 0 1)。用NEM预处理 ,能完全模拟HP的心肌细胞保护作用 ;而用PTX阻断Gi/o蛋白 ,或Forskolin和 8 Br cAMP预处理后 ,再给予HP及低氧 3h/复氧 1h ,则细胞生存率降低 ,LDH释放增加 (P <0 0 1) ;U 7312 2预处理后 ,细胞生存率和LDH释放量无差异 (P >0 0 5 )。结果提示 :Gi/o蛋白通过抑制AC ,减少第二信使cAMP的生成介导了HP的心肌保护作用。PLC可能不参与HP的心肌保护作用     

生长激素和催乳素放射免疫测定法的建立与应用

目的：建立测定大鼠垂体和血浆中生长激素（GH）和催乳素（PRL）含量的高特异性、高灵敏度的双抗放射免疫测定（RIA）法;研究急性低氧对垂体激素GH和PRL的作用。方法：用氯胺－T法进行抗原放射性碘标记;采用平衡饱和加样程序的双抗RIA法测定。结果：用该方法测定急性低氧（0．5h）时血浆和垂体GH和PRL含量,7km低氧,垂体GH含量明显升高（P＜0．05）,血浆则相反;7km低氧,明显降低垂体和血浆PRL含量（P＜0．01）;而5km低氧对GH和PRL的作用与对照组比无统计学差异。结论：本双抗RIA法具有高特异性、高灵敏度及简便易行等特性;用该法测定提示急性低氧可抑制大鼠GH和PRL的分泌。     

低氧对CD34~ 造血干/祖细胞增殖分化及其对细胞因子依赖性的影响

采用免疫磁珠法分离脐血CD34 造血干 /祖细胞 ,进行低氧和常氧条件下单个核细胞 (MNC)及CD34 细胞的半固体及液体培养 ,计细胞总数和集落产率 ,并通过流式细胞仪检测细胞表型和细胞周期 ,以探讨造血干/祖细胞在低氧环境下增殖分化性能的改变及其对细胞因子反应性的变化。结果显示 :CD34 细胞在低氧条件下生成的BFU E集落数 ( 32 4 8± 41 4/10 4 细胞 )明显增多 (对照为 191 2± 34 5 /10 4 细胞 ,P <0 0 1) ;在无细胞因子存在的液体培养体系中 ,低氧组的BFU E产率 ( 15 2 4± 2 2 6 /10 4 细胞 )明显高于常氧组 ( 74 2± 9 3/10 4 细胞 ,P <0 0 1) ;低氧培养细胞中CD34 细胞的比例高于对照 2 5± 1 2倍 (P <0 0 5 )。但MNC生成的BFU E在常氧和低氧条件下无显著差异。这些结果表明 :体外低氧环境能显著增加CD34 造血干 /祖细胞形成红系祖细胞的产率 ,且使其对细胞因子的依赖性降低 ,并对早期红系祖细胞的维持有增强作用 ,但对粒系祖细胞的增殖则有抑制作用     

银杏内酯对急性低氧时脑含水量、Na+,K+-ATPase活性、MDA、乳酸含量的影响

目的 :观察银杏内酯对急性低氧脑损伤的保护作用 ,并探讨其机理。方法 :用成年SD大白鼠分成常氧对照组 (NC组 ) ,急性减压低氧组 (AH组 ) ,银杏内酯加低氧组 (GH组 ) ,测定各组脑含水量 ,Na+,K+ ATP酶活性 ,丙二醛和乳酸的含量。结果 :①与NC组相比 ,AH组脑含水量明显增高 (P <0 .0 1) ,而GH组脑含水量较AH组明显降低 ,与NC组相近。②AH组脑Na+,K+ ATP酶活性较NC组明显下降 (P <0 .0 1) ,GH组该酶活性上升 (P <0 .0 5)。③AH组脑丙二醛含量明显高于NC组 ,GH组丙二醛含量较AH组显著降低 (P <0 .0 1)。④AH组脑乳酸含量显著高于NC组 ,而GH组乳酸含量明显低于AH组 (P <0 .0 1)。结论 :银杏内酯能减轻脑水肿 ,对抗氧自由基 ,提高Na+,K+ ATP酶活性 ,改善脑细胞能量代谢     

血管钠肽对低氧大鼠心脏钠尿肽C受体表达的影响

目的 :探讨低氧对大鼠心脏钠尿肽C受体 (NPR C)表达的调节作用 ,以及血管钠肽 (VNP)对这一过程的影响。方法 :将大鼠随机分为 3组 :对照组、低氧组 (3～ 2 8d)和VNP(2 5～ 75 μg/kgbw) 低氧组 ,采用放射免疫的方法测定大鼠血浆心房钠尿肽 (ANP)的浓度 ,并采用定量PCR的方法分析NPR C的mRNA水平。结果 :低氧 2 8d大鼠血浆ANP浓度显著高于正常大鼠 (P <0 .0 5 ) ,而且每天注射 75 μg/kgbw的VNP使ANP浓度进一步升高 (P <0 .0 1)。低氧 3d对大鼠心脏NPR C的mRNA的量没有显著影响 ;低氧 7d使大鼠心脏NPR C的mRNA的拷贝数显著升高 (P <0 .0 5 ) ;低氧 14d、2 8d使大鼠心脏NPR C的mRNA的拷贝数进一步升高 (P <0 .0 1)。每日注射 2 5μg/kgbw的VNP对低氧诱导的大鼠心脏NPR C表达没有显著影响 ;5 0 μg/kgbw的VNP显著降低低氧大鼠心脏NPR C的表达 (P <0 .0 5 ) ;75 μg/kgbw的VNP进一步降低低氧大鼠心脏NPR C的表达 (P <0 .0 1)。 结论 :VNP可以升高低氧大鼠的血浆ANP水平 ;低氧可以使大鼠心脏NPR C表达增加 ,而且具有时间依赖性 ,而VNP对这一过程有抑制作用 ,并且呈剂量依赖性     

间断性低氧对大鼠淋巴细胞转化的影响

目的: 探讨间断性低氧对机体免疫反应的影响.方法: 以模拟海拔高度间断性低氧(4 h/d)模型观察大鼠脾淋巴细胞对丝裂原(Con A)的反应性.结果: 与对照相比,5 km急性低氧4 h大鼠淋巴细胞的转化率下降25.43%(P<0.05) ,间断性低氧2、5、15 d后淋巴细胞转化率分别为97.03%、104.5%和99.55%,与对照组无明显差异.2 km间断性低氧(4 h/d)1、2、5、15 d,大鼠脾淋巴细胞转化率分别为93.19%、96.43%、99.03%和100.54%,与对照组无明显差异.脾单个核细胞DNA含量显示, 5 km急性低氧4 h DNA含量明显下降(76.22%±7.06%,P<0.05),间断性低氧5 d和15 d后与对照组无显著差异.结论: 急性低氧抑制淋巴细胞的转化,并随低氧的加重而增加,重复间断性低氧暴露其抑制作用减弱,引起大鼠淋巴细胞转化产生适应.推测免疫适应与HPA轴的适应有关.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.