P物质对心血管系统的作用

P物质的生理作用,主要表现在神经系统和心血管系统二方面,前者已有专文讨论;后者在国内期刊还未见介绍。本文对P物质在心血管系统的作用做一简介。一、降血压1931年von Euler从牛脑和肠提取出一种未知物质,发现它能降低动物的血压。当动脉或静脉注入部分纯的P物质或P物质的纯品,都能引起短时间的血压降低。降压作用适用于禽类、所有哺乳动物和人。降压效用的高低因动物的种属而异,对兔和狗引起降压的P物质阈剂量比猫和老鼠低,通常3～5个单位的P物质就能使兔子降压20毫米汞柱。使猫达到该降压值则需要20～30单位,所以常用兔,特别是用狗作实验对象。P物质对猴和人也能降压。     

福建产圆斑蝰蛇毒中性磷脂酶A2的降压作用与机理

福建产圆斑蝰蛇毒中性磷脂酶Ａ２（ＰＬＡ２－３）对麻醉Ｗｉｓｔａｒ大鼠、猫和家兔均产生急性降压效应,并具快速耐受性。该降压作用能被吲哚美辛取消。应用放射免疫法测定血浆前列环素（其稳定产物６－ｋｅｔｏ－ＰＧＦｌａ）含量,与给药前相比,降压高峰时血浆６－ｋｅｔｏ－ＰＧＦＩｌａ含量增高。离体入胃网膜动脉条实验观察到,ＰＬＡ２－３呈剂量依赖性降低入胃网膜动脉条静息张力;对预先用去甲肾上腺素或５－羟色胺收缩的人胃网膜动脉条也具松弛作用。结果表明该ＰＬＡ２降压机制与前列环素（ＰＧＩ２）的释放和外周血管扩张有关。     

哈慈五行针对家兔血液流变学的影响

应用哈慈五行针双极针法作用于大白兔经穴、体液8周后,由颈动脉取血,测试其血液流变学特征,并与对照组作比较,全血还原粘度五行针实验组为3．58,对照组为4．06。证明五行针对红细胞的聚集到了解聚作用,增强了红细胞的流动性,即在五行针的磁场作用下,红细胞表面电荷在洛仑兹力的作用下朝磁场和血液流动相垂直方向运动,红细胞的电泳速度加快,红细胞间相互排斥性增加,粘滞度下降,流动性提高。哈慈五行针对于临床改善血液的流变性、降低血液粘度、促进血液循环、具有实际意义。用于冠心病、高血压、脑血栓等循环系统疾病的预防和治疗。     

柠檬果皮中各种降压组分的分离精制及其结构

前言本文以柠檬果皮中各个降压组分的分离、精制及确定其结构为目的而进行的研究。以前,在柠檬果皮中具有降压作用的某些活性物质的分离、精制是采用热水抽提,凝胶过滤,高效液相色谱等方法进行。但出现的问题是:在液相色谱图中有其它杂质峰。因此,改用热水抽提,凝胶过滤后,做TLC法,虽然能取得较为满意的结果,但获得的量太少,后     

大功率微波急性辐照对血液流变特性的影响

用２．４５ＧＨｚ的连续微波对大白兔在体血液和人离体血液进行急性大剂量辐照,对辐照前和辐照后的血液粘度,粘弹性,血小板聚集性,红细胞脆性进行了实验研究,实验结果表明：微波辐照后兔血的粘度和粘弹性值降低,人血的粘度在低切变率下降低,在较高的切变率下升高;兔血小板聚集功能降低,二相聚集的解聚率增大;红细胞的脆性增大。     

大功率微波急性辐照对血液流变特性的影响

用２．４５ＧＨｚ的连续微波对大白兔在体血液和人离体血液进行急性大剂量辐照,对辐照前和辐照后的血液粘度,粘弹性,血小板聚集性,红细胞脆性进行了实验研究,实验结果表明：微波辐照后兔血的粘度和粘弹性值降低,人血的粘度在低切变率下降低,在较高的切变率下升高;兔血小板聚集功能降低,二相聚集的解聚率增大;红细胞的脆性增大。     

胍乙啶的血流动力作用

本文用正常血压及腎型高血压狗研究胍乙啶对心和腎的血流动力作用,并用大白鼠試驗其对循环及器官血容量的影响。根据Fick氏原則測定心輸出量,同时从腎脏对于对氨基馬尿酸及肌酐的清除率計算腎血流量及腎小球滤过率。靜脉注射胍乙啶5毫克/公斤1小时后,正常狗血压略有降低,高血压狗降压則較为明显。胍乙啶对正常血压狗的心輸出量、心搏量及心室作功量有減 低的趋向,而对腎型高血压狗則略有增加,但均不显著。胍乙啶不影响正常狗的外周血管阻力,而能显著降低腎型高血压狗的总外周阻力,扩张其外周血管。注射胍乙啶后,正常血压及腎型高血压狗的尿量增加均非常显著。腎型高血压狗的腎小球滤过率及腎血流量都非常显著地低于正常狗,腎血管阻力則大大地高于正常狗,靜脉注射胍乙啶后,滤过率及血流量均明显增加,而血管阻力則大大降低。正常大白鼠腹腔注射胍乙啶20毫克/公斤后,3小时內循环血量略有增加,但不显著,6小时后开始恢复,2斗小时后回至原水平。对注射DOCA的大白鼠的循环血量則沒有明显影响。正常大白鼠注射胍乙啶后,各器官及組織內合血量普遍有增加趋势,其中以脾及腎的血容量增加最为明显,說明胍乙啶对这些部位的血管有扩张作用。上述資料証明:胍乙啶的降压作用并非通过循环血量的減少,而是由于外周血管的扩张所致。胍乙啶能扩张腎血管,改善腎缺血状态,从而緩解腎型高血压的病理生理过程。     

蛇毒中的降压成分研究进展

目前世界上已知的蛇类有3000余种,其中有毒蛇约占20%。蛇毒是一种由蛋白质、多肽等有机和无机小分子组成的复杂混合物,因其具有多种生化和药理活性,能广泛应用于各个领域。研究表明蛇毒对血压有一定影响,其降压机制主要有蛇毒抗凝血因子Ⅱ通过介导NO的释放降低血压,缓激肽增强肽主要通过抑制血管紧张素转换酶和增加内源性缓激肽的作用而发挥作用,利钠肽通过抑制肾素-血管紧张素和醛固酮系统调控血压,而磷脂酶A_2主要是促进游离脂肪酸(其中最重要的是花生四烯酸)和溶血磷脂的释放起到降低血压的作用。因此,明确蛇毒的降压成分以及作用机制与效果,对降压药物的开发以及高血压的治疗至关重要。     

利血平降压机制中的副交感因素

在麻醉条件下,阿托品能在切除肾上腺的大白鼠产生降压作用;但在切除腎上腺的利血平化动物,降压作用反转为升压作用。这种升压作用既不被可卡因所增敏,又不被苄唑啉所拮抗,故与交感机制无关。同时,新斯的明的降压效应又能被利血平化所显著增强。因此认为,在利血平的降压机制中除了目前公认的交感神经功能低落的因素外,尚有副交感神经张力提高的因素参与,而上述条件下阿托品的升压作用乃其抗副交感作用的表现。     

家兔第四脑室注射乙酰胆碱对肺动脉血压的影响

本工作将乙酰胆碱(ACh)注入麻醉家兔第四脑室,观察其对肺动脉血压的影响。结果发现(1)脑室注射50—100μg ACh后,肺动脉压和颈动脉压均下降。与此同时心率也出现一过性减慢。(2)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低肺动脉压和颈动脉压的作用不受到任何影响。(3)预先由第四脑室注射阿托品,可阻断AGh引起的肺动脉降压反应和颈动脉降压反应。(4)第四脑室注射六甲双铵或酚妥拉明,均不能阻断这二个降压反应。(5)第四脑室注射心得安不能阻断ACh引起的肺动脉降压反应,但能阻断ACh降低颈动脉压的作用。 实验结果表明:脑中ACh水平升高可通过激活胆碱能M-受体引起肺动脉压和颈动脉压下降;在ACh引起的颈动脉降压反应的中枢环节中有肾上腺素能β-受体活动参与;而且ACh降低肺动脉压和颈动脉压的作用不是通过迷走神经实现的,可能是由于延髓交感缩血管中枢紧张性降低所造成的。     

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.