左旋硝基精氨酸对肺缺血预处理的抗缺血/再灌注损伤作用的影响

目的:观察一氧化氮合酶(NOS)阻滞剂左旋硝基精氨酸(L-NNA)对肺缺血预处理的影响,探讨NOS在肺缺血预处理效应中的作用.方法:40只日本大耳兔随机分成假手术(S)组,缺血/再灌注组(I/R组),缺血预处理组(IPC组)和左旋硝基精氨酸组(LNNA组),观察各组血浆丙二醛(MDA)含量、超氧歧化酶(SOD)活力,肺组织湿干重比(W/D),肺损伤定量评价指标(IQA),肺组织NOS活力以及肺组织超微结构变化.结果:IPC组与I/R组比较,MDA、W/D、IQA下降(P＜0.05或P＜0.01),SOD活力上升(P＜0.05),总NOS(TNOS)、原生型NOS(cNOS)活性明显增高(P＜0.05),电镜下肺组织损伤较轻;而预先用L-NNA(LNNA组)后使上述改变发生逆转.结论:左旋硝基精氨酸可以拮抗肺缺血预处理的抗缺血再灌注损伤作用;NOS可能是介导肺IPC效应的重要酶蛋白.     

N-亚硝基左旋精氨酸的心血管效应及其对肾交感神经活动的影响

在麻醉大鼠观察了新型NO合成抑制剂N-亚硝基左旋精氨酸(L-NNA)的血流动力学效应及其对肾交感神经活动的影响,旨在阐明NO在全身动脉血压调节中的可能作用及其作用机制。实验结果如下:(1)静注L-NNA(15 mg/kg)后,平均动脉压(MAP)由9.87±0.80升至14.67±0.53kPa(P<0.001),心率(HR)由317±13减至303±14 bpm(P<0.05),心指数(CI)由9.79±0.83降至7.04±0.41ml/min·100g~(-1)(P<0.05),总外周阻力指数(TPRI)由1.04±0.10升至2.15±0.18 u/100 g(P<0.001),持续30min以上;此效应可被预先注射左旋精氨酸(200 mg/kg)所逆转。(2)在缓冲神经切断的大鼠,i.v.L-NNA时,MAP,CI和TPRI的变化依然存在,而HR则加快,表明神经完整大鼠的HR减慢系压力感受器反射所致。(3)在缓冲神经完整大鼠i.v.L-NNA后,MAP升高,HR减慢,而肾交感神经活动(RSNA)无明显改变。(4)切断缓冲神经后,再i.v.L-NNA时,MAP,HR和RSNA分别增加55.6％、5.1％和34.3％,提示L-NNA可能兴奋交感中枢,而压力感受器反射可掩盖其对RSNA的影响;预先注射左旋精氨酸则可抑制L-NNA的上述效应。根据以上结果似可认为,NO合成抑制剂的血流动力学效应,由两种机制所介导:一是L-NNA抑制外周部位NO的基础性释放,致使血管紧张度增加,进而血压升高;另一是L-NNA兴奋交感中枢,从而引     

硝基左旋精氨酸对睡眠抑制作用的机制研究

本文观察了硝基左旋精氨酸（Ｌ－ＮＮＡ,５０ｍｇ／ｋｇ,ｉｐ）和Ｌ－精氨酸（Ｌ－ａｒｇ,１１０ｍｇ／ｋｇ,ｉｐ）对慢性植入电极的大鼠睡眠－觉醒周期的影响及中缝核５－羟色胺（５－ＨＴ）神经元免疫阳性反应的变化。结果表明：Ｌ－ＮＮＡ显著抑制慢波睡眠和快眼动睡眠,使平均动脉压（ＭＡＰ）升高。Ｌ－ａｒｇ则使ＭＡＰ显著降低,对睡眠无明显影响。预先给予Ｌ－ａｒｇ可逆转Ｌ－ＮＮＡ的效应。腹腔给予Ｌ－ＮＮＡ后２ｈ,     

L-Arg促使大鼠AEP演变为AHNP的大鼠模型及

目的　介绍一种急性水肿性胰腺炎(AEP)向急性出血坏死性胰腺炎(AHNP)演变的大鼠模型,并对其超微结构进行了观察。方法　30只SD大鼠随机分为正常组、AEP组和左旋精氨酸(L-Arg)干预组。通过阴茎背静脉注射雨蛙素诱导AEP模型后,再经该静脉注入L-Arg 1600mg/kg,以观察血清生化指标和胰组织的光镜、透射电镜下改变。结果　血清淀粉酶、脂肪酶水平在AEP组、L-Arg干预组均明显高于对照组,其中血清淀粉酶在两组间无显著性差异,而L-Arg干预组的血清脂肪酶却明显高于AEP组;AEP组的血清、胰组织NO浓度明显低于对照组,而L-Arg组明显高于对照组和AEP组。光镜及透射电镜证实,L-Arg干预AEP大鼠后,导致了胰实质出血、坏死和腺泡细胞内亚细胞结构的破坏。结论　L-Arg导致AEP加重为AHNP,与NO的毒性有关;此大鼠模型不但有血清淀粉酶等生化指标的改变,而且组织病理特点也较为典型,是研究急性胰腺炎重型化机理的良好模型。     

L—NNA 和还原型Hb对SHRsp肠系膜动脉内皮依赖性舒张的影响

我们以主往的工作证实成年自发高血压大鼠肠系膜动脉由乙酰胆碱引起的内皮依赖性舒张减弱,为进一步探讨ＥＤＲ减弱的机制,本文观察了一氧化氮合成酶抑制剂左旋硝基精氨酸及ＥＤＲＦ灭活剂还原型血红蛋白对卒中易感型自发高血压大鼠与常压对照大肠系膜动脉,ＡＣｈ内皮依赖性舒张的影响,发现Ｌ－ＮＮＡ（１０＾－３ｍｏｌ／Ｌ）可使ＳＨＲｓｐ弱于ＷＫＹ的ＡＣｈ ＥＤＲ（１０＾－８－１０＾－５ｍｏｌ／Ｌ）的差异消失,ＲＨｂ（     

L-Arg促使大鼠AEP演变为AHNP的大鼠模型及超微结构观察

目的　介绍一种急性水肿性胰腺炎(AEP) 向急性出血坏死性胰腺炎(AHNP) 演变的大鼠模型,并对其超微结构进行了观察。方法　30 只SD大鼠随机分为正常组、AEP组和左旋精氨酸(L- Arg) 干预组。通过阴茎背静脉注射雨蛙素诱导AEP模型后,再经该静脉注入L- Arg 1600mg/kg,以观察血清生化指标和胰组织的光镜、透射电镜下改变。结果　血清淀粉酶、脂肪酶水平在AEP组、L- Arg 干预组均明显高于对照组,其中血清淀粉酶在两组间无显著性差异,而L- Arg 干预组的血清脂肪酶却明显高于AEP组;AEP组的血清、胰组织NO浓度明显低于对照组,而L- Arg 组明显高于对照组和AEP组。光镜及透射电镜证实,L- Arg 干预AEP大鼠后,导致了胰实质出血、坏死和腺泡细胞内亚细胞结构的破坏。结论　L- Arg 导致AEP加重为AHNP,与NO 的毒性有关;此大鼠模型不但有血清淀粉酶等生化指标的改变,而且组织病理特点也较为典型,是研究急性胰腺炎重型化机理的良好模型。     

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.