过氧化物酶体增殖物激活受体与细胞凋亡调控

利用核受体与配体作用促进癌细胞分化和凋亡是治疗癌症的新方向。过氧化物酶体增殖物激活受体(PPARs)是一类参与多种生物学效应的核受体,目前已知有3种亚型：α、β和γ。PPARs除和脂质代谢、氧化还原状态、炎症、心血管疾病、糖尿病、肥胖等一系列生理过程密切相关外,PPARs的激活还对细胞的生长、分化甚至凋亡有重要的影响,尤其是PPARγ的激活在多种恶性肿瘤细胞中可促进细胞凋亡、抑制肿瘤生长。然而由于PPARs的表达具有极大的物种、组织特异性,使预临床实验的推广应用变得十分复杂。现仅就PPARs与细胞凋亡方面的最新研究进展及其在癌症预临床中的研究状况进行综述。     

过氧化物酶体增长因子活化受体（PPARs）与microRNAs

在细胞中,过氧化物酶体增长因子活化受体（PPARs）和microRNAs相互制约和调控从而影响相关细胞、组织和器官的功能,在脂肪细胞分化与代谢、炎症、癌症和心血管疾病等生理和病理过程中发挥重要作用.本文首先简要总结了PPARs发挥作用的分子机制;并分别以PPARs家族每一个成员（PPARα、PPARβ和PPARγ）为对象,分析了PPARs调控下的microRNAs表达及功能,探讨了microRNAs调控下的PPARs表达活性变化,并归纳了PPARs与microRNAs之间的调控关系;最后对PPARs相关microRNAs的应用前景进行了简单探讨.研究PPARs与microRNAs间的网络调控关系,可以为PPARs与microRNAs在理论和实践中的深入研究和应用提供参考.     

PPAR基因与脂肪代谢调控

过氧化物酶体增值剂激活受体(PPARs)基因属于类固醇/甲状腺/维甲酸受体超家族,有3个亚型,即：PPAR-α、PPAR-β和PPAR-γ。PPARs具有多种生物学功能,如增强机体对胰岛素敏感性,调节体内糖平衡等,尤其在脂肪分化、生成等多方面起到重要作用,是目前的研究热点,文章从PPARs基因的结构,表达及功能等方面讨论了其与脂肪代谢调控的关系。     

脂质过氧化物体增殖物激活受体研究概况

脂质过氧化物体增殖物激活受体(peroxisome proliferator-activated receptors,PPARs)家族由PPARα、PPARβ／δ和PPARγ三种核受体组成。PPARs是配体调节的转录因子,与另外一种核受体视黄醛衍生物X受体(RXR)形成异二聚体,结合到靶基因启动子区的特异反应元件(PPRE)上,从而发挥重要的调节基因表达的作用。现在已知有多种天然及合成的PPARs配体,其中,合成药物fibrates(PPARα配体)及thiazolidinediones(PPARγ配体)分别能有效地治疗血脂异常及2型糖尿病。利用这些配体对PPARs进行研究,揭示了PPARs在脂肪形成、脂质代谢、糖稳态、胰岛素敏感性、细胞生长及分化、动脉粥样硬化、炎症及肿瘤等多种生理及病理生理过程中的重要作用。本文对PPARs的结构、组织分布、主要配体,以及它们在健康和疾病状态下的作用进行综述。     

PPARs信号通路与哺乳动物生殖

过氧化物酶体增殖因子活化受体(peroxisome proliferator-activated receptors,PPARs)在动物体内有着广泛的生物学作用,可调节脂类代谢、能量收支平衡以及细胞分裂分化等重要生理过程。已经发现,PPARs信号通路与糖尿病和癌症等许多重大疾病的发生有关。随着基因剔除技术的应用以及PPARs人工配体的开发利用,人们对PPARs的认识不断深入。现对PPARs通路在卵巢周期、黄体形成、胚胎着床、胎盘发育和雄性生殖等哺乳动物生殖系统中的表达、功能及作用机制进行综述。     

脂质过氧化物酶体增殖物激活受体在心脏生理与病理中的作用

心肌能量代谢状况是其结构与功能的重要决定因素,调节能量代谢是心脏疾病的有效疗法之一.脂质过氧化物酶体增殖物激活受体(PPARs)是一组具有复杂功能的核受体超家族成员,与脂肪形成、糖脂代谢、炎症及肿瘤发生等多种生物过程有关.PPARs可通过调控编码脂肪酸与糖类氧化相关酶的基因转录而调节心肌代谢,在心脏多种疾病病理过程中其表达与活性均有明显变化,因此已被作为心脏病的治疗靶点之一.本文对PPARs在心脏生理与病理中的作用进行简要介绍.     

PGI2-PPARδ信号传导途径与哺乳动物的胚胎着床

前列腺素 (PGs)在胚泡着床和子宫的蜕膜化过程中起着重要的调节作用 ,前列环素 (PGI2 )是着床位点表达量最高的PGs .前列环素受体 (IP)和过氧化物酶体增殖因子活化受体 (PPARs)分别是PGI2 的细胞表面G蛋白偶联的受体和细胞核内受体 ,IP在胚泡着床位点不表达或检测不到 ,而PPARδ表达丰富 ,RXRs (PPARs的异二聚体伴侣 )及相应的PPARδ RXRα复合物、PGI2 合成酶 (COX 2 /PGIS)也在着床位点表达丰富 ,因此推测PGI2 在胚泡着床中的作用可能是通过PPARδ受体介导的 .利用PGI2 类似物 (cPGI)和PPARδ特异性类似物能够恢复COX 2基因敲除小鼠的胚泡着床和蜕膜化 .总之 ,PGI2 通过PPARδ在胚泡着床和蜕膜化过程中起着重要的调节作用     

过氧化物酶体增殖物激活受体与动脉粥样硬化

过氧化物酶体增殖物激活受体 (peroxisomeproliferator activatedreceptors ,PPARs)是核受体超家族中的一类配体依赖的核转录因子 ,包括α、β/δ和γ三种亚型 ,在脂肪细胞分化、能量代谢和炎症过程中都发挥重要的作用。最近的研究显示 ,PPARs的活化不仅可以改善包括糖尿病、高血压和肥胖等在内的胰岛素抵抗综合征 ,而且还直接作用于血管壁 ,从而减缓动脉粥样硬化的进程。本综述将就PPARs的结构、功能、与动脉粥样硬化发病机制和治疗相关的最新研究进展进行简要介绍。     

作用于过氧化物酶体增殖物激活受体药物的研究进展

过氧化物酶体增殖物激活受体(peroxisome proliferator-activated receptors,PPARs)是被脂肪酸等内源性配体、外源性过氧化物酶体增殖剂(peroxisome proliferators,PP)激活,进而调控参与脂类代谢某些酶基因表达的转录调节因子。PPARs与糖脂代谢性疾病、炎症及某些肿瘤的发生发展密切相关。PPARs激动剂和其部分激动剂主要用于治疗糖尿病,另外其拮抗剂同其一样也用于炎症和肿瘤的治疗。现就作用于PPARs药物的研究进展进行了综述。     

PGI2-PPARδ信号传导途径与哺乳动物的胚胎着床

前列腺素（PGs）在胚泡着床和子宫的蜕膜化过程中起着重要的调节作用,前列环素(PGI₂)是着床位点表达量最高的PGs.前列环素受体(IP)和过氧化物酶体增殖因子活化受体(PPARs)分别是PGI₂的细胞表面G蛋白偶联的受体和细胞核内受体,IP在胚泡着床位点不表达或检测不到,而PPARδ表达丰富,RXRs（PPARs的异二聚体伴侣）及相应的PPARδ-RXRα复合物、PGI₂合成酶（COX-2/PGIS）也在着床位点表达丰富,因此推测PGI₂在胚泡着床中的作用可能是通过PPARδ受体介导的.利用PGI₂类似物（cPGI）和PPARδ特异性类似物能够恢复COX-2基因敲除小鼠的胚泡着床和蜕膜化.总之,PGI₂通过PPARδ在胚泡着床和蜕膜化过程中起着重要的调节作用.     

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.