黄伞胞外多糖抗自由基作用的研究

目的:以乙醇沉淀的黄伞发酵浓缩液得到的胞外多糖为研究对象,检验其对自由基的清除作用。方法:采用电子顺磁共振(EPR)波谱仪检测黄伞胞外多糖清除羟自由基OH.和超氧阴离子自由基O2-.的作用。结果:在样品浓度均为100mg/mL的条件下,利用Fenton反应体系,黄伞胞外多糖对羟自由基OH.的清除率仅为38.5%;而利用次黄嘌呤-黄嘌呤氧化酶体系,黄伞胞外多糖对超氧阴离子自由基O2-.的清除率可达到80.6%。结论:黄伞胞外多糖在体外对自由基有一定的清除作用且其对超氧阴离子自由基O2-.的清除作用明显优于对羟自由基OH.的清除作用。     

超声参数对白术多糖抗氧化活性的影响

采用热水浸提和超声辅助法提取白术多糖,研究白术多糖的总还原能力以及对超氧阴离子(O2-·)、羟基自由基(·OH)、1,1-二苯基-2-苦苯肼自由基(DPPH·)的清除作用.结果表明:超声频率80 kHz,功率220 W时,白术多糖提取率达到最大(8.017％),明显高于热水浸提法所得(6.832％).白术多糖对·OH和DPPH·具有较强的清除作用,随着质量浓度的升高,·OH清除率呈上升趋势.超声功率和频率均对白术多糖的抗氧化活性有影响且超声功率的影响较大.随着超声功率的提高,白术多糖清除·OH的能力增强,但对O2-·的清除能力影响较弱.     

冬葵果多糖的抗氧化作用研究

研究冬葵果多糖(Fructus Malvae polysaccharides,FMP)对氧自由基的清除作用及对脂质过氧化的抑制作用。采用分光光度法测定FMP清除Fenton体系产生的羟自由基(.OH)、邻苯三酚自氧化体系产生的超氧阴离子自由基(O2-.)的能力及评价对Fe(Ⅱ)-H2O2体系(.OH)诱导的脂质过氧化终产物丙二醛(MDA)的抑制作用。结果显示,在化学模拟体系中,冬葵果多糖对.OH具有很强的清除作用,与VC比较达到显著水平(P<0.01),对O2-.的清除能力与VC相当。在体外,多糖浓度达到1.72 mg/mL可明显降低MDA的含量,与空白液比较达到显著水平(P<0.01)。以上结果表明,FMP具有明显的抗氧化活性。     

杨桃提取物体外清除氧自由基作用

从杨桃果中提取得到三种提取物为匀浆提取物、蛋白提取物和多糖提取物。采用化学发光法测定这三种提取物清除氧自由基的活性,实验结果:匀浆提取物清除羟自由基(·OH)和H2O2的活性大小相近,而清除超氧阴离子自由基(O2–·)的活性较小,其IC50约为前两者的4倍。蛋白提取物清除O2–·和·OH的活性大小相近,而清除H2O2的活性明显小于前两者,IC50约为前两者的9倍。多糖提取物清除.OH的活性明显大于清除O2–·和H2O2的活性,其IC50约为O2–·的1/22,约为H2O2的1/65。结果表明,杨桃果具有清除O2–·、·OH和H2O2的作用,不同提取物对这些活性氧自由基的清除能力有所不同。     

泥鳅多糖清除活性氧和保护DNA链的作用

采用化学发光法和分光光度法在多种化学模拟体系中研究了泥鳅多糖清除活性氧的作用 ,并用化学发光法观察了泥鳅多糖对·OH导致DNA链损伤的抑制作用。结果表明 ,泥鳅多糖能够有效地清除O·-2 、·OH、H2 O2 等活性氧 ,对DNA链具有良好的保护作用     

灰树花多糖的提取及抗氧化活性

采用单因素和正交试验法对热水浸提、超声波辅助和微波辅助提取灰树花多糖的工艺进行研究,分别获得了3种方法的最佳条件,并发现微波辅助法最佳,其最优条件为:微波功率800 W、微波时间3 min,浸提2h,多糖得率为13.05％,比热水浸提法提高了51.22％.利用提取的灰树花多糖进行抗氧化性研究,发现灰树花多糖对O2-·和·OH都具有一定的清除作用,且多糖浓度与其对O2-·的清除作用存在量效关系,但不如·OH明显.     

山药蛋白多糖体外抗氧化作用的研究

目的:测定山药蛋白多糖体外抗氧化作用.方法:山药经破碎匀浆,水浸提,离心收集上清液减压浓缩,用Sevag法除去游离蛋白质,收集沉淀复溶,透析48h,冷冻干燥得山药蛋白多糖.采用辣根过氧化酶法、核黄素光照法、Fenton反应2-脱氧-D-核糖法等生物化学方法分别测定了山药蛋白多糖对H2O2、O2-、·OH的清除能力,用硫代巴比妥酸法、分光光度法分别测定山药蛋白多糖对小鼠肝组织脂质过氧化反应和小鼠红细胞溶血的抑制作用.结果:山药蛋白多糖对活性氧自由基如H2O2、O2·-、·OH具有良好的清除作用,可减少红细胞溶血和抑制小鼠肝匀浆脂质过氧化反应,在一定范围内和剂量成正比.结论:山药蛋白多糖具有明显的体外抗氧化作用,其体外抗氧化能力与蛋白多糖浓度呈正相关性.     

荸荠皮多糖体外清除自由基活性的研究

采用DPPH自由基法、邻苯三酚自氧化法和水杨酸法分别表征了荸荠皮多糖清除DPPH自由基(DPPH.)、超氧阴离子自由基(O2-.)和羟基自由基(.OH)的能力。结果显示,脱蛋白和未脱蛋白荸荠皮多糖具有清除自由基的活性,但该活性明显低于茶多酚。脱蛋白多糖清除DPPH.的能力高于未脱蛋白多糖,其清除50%DPPH.的作用质量浓度(EC50)分别为50.26 mg.L-1和76.22 mg.L-1。两种多糖清除.OH和O2-.的能力相当,其EC50(g.L-1)分别为0.118和0.124以及10.87和9.53。     

红车轴草总黄酮体外清除自由基作用的研究

通过Fenton 反应产生·OH,邻苯三酚自氧化产生O·-2模型,研究了红车轴草总黄酮体外清除自由基的作用.结果显示红车轴草总黄酮在6.25～200 mg/mL范围内具有清除Fenton 反应产生·OH的作用,在6.25～100 mg/mL浓度范围内对邻苯三酚自氧化产生的O·-2具有清除作用,二者均呈明显的量效关系,对·OH和O·-2半数清除浓度分别为44.06 和54.57 mg/mL.     

夏枯草多糖的分离纯化与抗氧化活性研究

对夏枯草多糖(PP2)的分离纯化方法作了探讨,通过正交试验,筛选出多糖提取条件的最佳组合。采用纸层析、琼脂糖凝胶电泳和紫外分光光度法对多糖纯度进行鉴定。通过气相色谱仪对多糖的单糖组成进行分析。通过体外化学模拟,研究夏枯草多糖的抗氧化性。实验表明,夏枯草多糖对O2-.、.OH二种自由基及亚硝酸根离子具有一定的清除能力,对R.自由基的清除较弱,具有防止膜脂质过氧化,减少红细胞溶血和降低脂质过氧化产物丙二醛的生成量的作用。     

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.