刺激家兔颈交感神经对颈动脉窦反射的影响

在36只麻醉家兔观察了电刺激颈交感神经(CSN)对颈动脉窦压力感受器(CSB)活动的影响。所得结果如下:(1)电刺激 CSN 可使夹闭颈动脉引起的加压反射消失或倒转,△BP 从刺激前的 39.5±3.6mmHg 变为刺激时的-0.31±5.4mmHg(P<0.001)。(2)在电刺激CSN 时,静注新福林所诱发的颈动脉窦压力感受器-心率反射增强,表现为反射性心率减慢较刺激前更为明显。(3)在以50—200mmHg 的压力充胀两侧颈动脉窦的条件下,刺激 CSN 引起窦内压与平均动脉压的关系曲线下移,与刺激前曲线相比有明显差异(P<0.01)。(4)切断 CSN 后,动脉血压有所升高,提示 CSN 对 CSB 活动有紧张性调节作用。以上结果比较明确地表明家兔 CSN 对 CSB 活动有调节作用。此作用可能是 CSN 作用于窦壁平滑肌而间接引起的。     

心房钠尿因子对颈动脉窦压力感受器反射的易化作用

在麻醉大鼠观察了心房肽Ⅲ(AtriopeptinⅡ,APⅡ)对颈动脉窦压力感受器活动的影响,并在麻醉家兔观察了APⅡ作用于颈动脉窦区时窦神经传入放电的改变。结果如下:(1)用APⅡ(1μg/ml)隔离灌流大鼠左侧颈动脉窦区(n=10),压力感受器反射的阈压(TP)无明显改变,平衡压(EP)由101±2.8降至95±2.0 mmHg(P<0.05),饱和压(SP)由202±5.2降至168±6.1 mmHg(P<0.001),而工作范围(OR)由128±5.5减至93±6.3mmHg(P<0.001),压力感受器机能曲线向左下方移位,曲线最大斜率(PS)由0.77±0.04增大为1.07±0.13mmHg·mmHg~(-1)(P<0.05);(2)在用硝普钠(NP,0.5μg/ml)灌流的动物(n=6),TP和 EP 无改变,SP 由188±6.4升至218±6.0 mmHg(P<0.01),OR 由107±6.9增至132±7.6 mmHg(P<0.05),硝普钠对压力感受器机能曲线及其 PS 无显著影响;(3)恒压隔离灌流兔颈动脉窦区时,窦神经传入放电具有良好的稳定性,升高窦内压(ISP)时,窦神经传入放电也随之增多。用 APⅡ(1μg/ml)恒压灌流时,窦神经传入放电增加20.9±3.9%(n=6,P<0.01),冲洗掉 APⅡ后,窦神经传入放电恢复至对照水平。以上结果显示,APⅢ可使大鼠颈动脉窦压力感受器机能曲线向左下方移位,曲线最大斜率增大以及兔窦神经传入放电增加,表明 APⅡ对颈动脉窦压力感受器活动有易化作用。这     

KATP通道开放剂对颈动脉窦压力感受器反射的易化作用

在30只隔离灌流颈动脉窦区的麻醉大鼠, 观察了KATP通道开放剂(cromakalim, Cro)对颈动脉窦压力感受器反射的影响.结果如下: (1)以Cro (10 μmol/L)隔离灌流大鼠左侧颈动脉窦区时, 压力感受器机能曲线向左下方移位, 曲线最大斜率 (PS) 由0.36±0.01增至0.48±0.01 kPa/kPa (P<0.001), 反射性血压下降幅度(RD)由5.78±0.14增至7.87±0.12 kPa (P<0.001);阈压(TP)、平衡压(EP)和饱和压(SP)则分别从8.34±0.35, 12.71±0.25和24.89±0.25下降至6.41±0.09 kPa, 11.78±0.24 kPa, 22.56±0.16 kPa (P<0.01～0.001).其中RD, PS和TP的变化呈明显的剂量依赖性.(2)用KATP通道阻断剂格列苯脲(glibenclamide, 10 μmol/L)预处理后, Cro的上述反射效应即被阻断.(3)先给予腺苷(adenosine, 125 μmol/L)则可以加强Cro对压力感受器反射的影响.以上结果表明, KATP通道开放剂Cro对大鼠颈动脉窦压力感受器反射有易化作用, 此作用是由KATP通道开放剂引起窦壁扩张而牵张压力感受器所致.     

兔肾性高血压时的动脉压力感受器反射

14只雄性家兔在双肾缩扎术后12周,经氨基甲酸乙酯静脉麻醉,分别在缓冲神经完整、切断两侧减压神经或切断两侧窦神经后静注新福林或硝普钠升降血压以改变动脉压力感受器活动,观察其心率、后肢血管阻力和肾交感神经活动的反射性变化,并与正常血压兔的反射效应相比较。主要结果如下:(1) 动物双肾动脉缩扎后12周,平均动脉血压(131±9mmHg)较正常动物血压(95±10mmHg)有显著升高(P<0.001);(2) 缓冲神经完整时,新福林和硝普钠升降血压诱发的心率反射性变化与正常血压动物相比显著减弱(P<0.001),而后肢血管阻力和肾交感神经活动的反射性调节无明显改变,表明肾性高血压动物的心率反射性调节与外周循环的反射性调节机能不相平行;而由股动脉内直接注射新福林或硝普钠时,股动脉灌流压的增减幅度与正常血压动物相比并无明显差异;(3) 切断两侧减压神经或切断两侧窦神经后,在正常动物仅使反射性心率调节作用减弱,而后肢血管阻力和肾交感神经活动的反射性调节无明显改变;但在高血压动物,除心率的反射性调节进一步减弱外,新福林和硝普钠升降血压时后肢血管阻力和肾交感神经活动的反射性调节效应也显著地减弱(P<0.001),提示肾性高血压时动脉压力感受器反射的潜在调节能力降低。由此似表明,肾性高血压时动脉压力感受器反射     

脑内γ—氨基丁酸（GABA）在急性失血性低血压时对血压的影响

本实验通过大鼠和家兔侧脑室注射GABA受体阻断剂荷包牡丹碱(Bicuculline)研究正常血压和急性失血性低血压时,中枢GABA对血压的调节作用。结果表明:在两种情况下,荷包牡丹碱均有明显的升压作用,但后者显著大于前者,且这种升压效应不被去肾或去肾上腺所影响。同时发现:急性失血性低血压时,兔脑脊液中GABA含量明显增加,提示在急性失血性低血压时,中枢GABA具有阻止血压回升的作用,这种作用是通过对中枢交感神经系统的抑制引起的。     

颈交感神经阻滞对严重烧伤大鼠的救治作用及其机制研究

目的:观察颈交感神经阻滞(CSB)对严重烧伤大鼠的救治作用,并对其可能机制进行初步探讨。方法:将大鼠随机分为正常对照组、烧伤组和CSB组,烧伤组与CSB组均制作20%体表面积Ⅲ0烧伤模型,CSB组于致伤后进行颈交感神经阻滞,观察动脉血压和心率变化;测定大鼠血中皮质酮、肾上腺素浓度;观察伤后21天动物伤死情况。结果:1.颈交感神经对严重烧伤大鼠救治效果显著,烧伤组和CSB组动物21天死亡率分别为73.33%和53.33%;2.创伤后大鼠血浆内肾上腺素浓度在伤后24小时有明显上升,然后迅速下降,但是CSB组肾上腺素浓度上升幅度远远低于烧伤组;3.与正常组相比,烧伤后血清GC的水平升高非常显著,CSB治疗组虽较正常组也升高,但显著低于烧伤组。结论:颈交感神经阻滞对严重创伤动物具有明显保护效应,其保护作用机制可能与调节创伤后神经-内分泌-免疫系统功能紊乱有关。     

链霉素对颈动脉窦压力感受器反射的抑制作用

在 2 3只隔离灌流颈动脉窦区的麻醉大鼠 ,观察了链霉素对颈动脉窦压力感受器反射的影响。结果如下 :(1)以链霉素 (10 0 μmol/L)隔离灌流大鼠左侧颈动脉窦区时 ,压力感受器反射机能曲线向左下方移位 ,曲线最大斜率 (PS)由 0 40± 0 0 1kPa降至 0 33± 0 0 1kPa (P <0 0 0 1) ,血压反射性下降 (reflexdecrease ,RD)幅度由 6 2 2±0 13kPa降至 5 0 2± 0 11kPa (P <0 0 0 1) ,阈压 (TP)、平衡压 (EP)和饱和压 (SP)则分别从 8 2 7± 0 2 5 ,12 71± 0 2 1和 2 4 41± 0 14kPa增至 10 33± 0 32 (P <0 0 1) ,13 33± 0 30 (P <0 0 1)和 2 6 11± 0 2 8kPa (P <0 0 1)。其中RD ,PS和TP的变化呈明显的剂量依赖性。 (2 )应用腺苷隔离灌流大鼠颈动脉窦区 ,引起颈动脉窦压力感受器反射的易化 ;在用链霉素预处理后 ,此易化效应不仅完全被阻断 ,且可使反射效应小于应用腺苷前的对照值。以上结果表明 ,链霉素对大鼠颈动脉窦压力感受器反射有明显的抑制作用。     

银杏苦内酯B抑制麻醉大鼠颈动脉窦压力感受性反射

本研究在30只麻醉雄性Sprague-Dawley大鼠隔离灌流颈动脉窦区观察了银杏苦内酯B(ginkgolide B)对颈动脉窦压力感受性反射的影响.结果显示:(1)银杏苦内酯B(0.1,1,10 pmol/L)隔离灌流序侧颈动脉窦区,使压力感受性机能曲线向右上方移位,曲线最大斜率(peak slop,PS)减小,血压反射性下降(reflex decrease,RD)幅度减小(P<0.01),阂压(threshold pressure,TP)、平衡压(equilibrium pressure,EP)和饱和压(saturation pressure,SP)均升高(P<0.05,P<0.01).其中PS、RD、TP、EP和sP呈明显的剂量依赖性;(2)预先应用钙通道开放剂Bay K8644(500 nmol/L),可以完伞取消银杏苦内酯B的抑制作用.(3)预先应用钾通道阻断剂四乙铵(tetraethylammonium,TEA,1 mmol/L),银杏苦内酯B的上述作用也被完全取消.结果表明,银杏苦内酯B对大鼠颈动脉实压力感受性反射有抑制作用,此作用与银杏苦内酯B减少颈动脉窦压力感受器神经末梢钙离子内流和增加钾离子外流有关.     

腺苷易化大鼠颈动脉窦压力感受器的活动

在36只麻醉大鼠,以隔离灌流颈动脉窦区记录窦神经传入放电的方法观察了腺苷（adenosine,Ado）对颈动脉窦压力感受器传入放电的影响。所得结果如下：（1）以75μmol／LAdo隔离灌流大鼠左侧颈动脉窦区时,窦内压-窦神经传入放电积分（ISP－ISNA）关系曲线向左上方移位,曲线最大斜率（PS）由（18．75±0．12）％／kPa增至（22．21±0．11）％／kPa（P＜0．001）,最大积分值（PIV）由（209．83±2．57）％增至（239．17±1．75）％;阈压（TP）和饱和压（SP）则分别从（8．57±0．24）和（22．99±0．34）下降至（7．15±0．23）kPa（P＜0．001）和（21．21±0,43）kPa（P＜0．01）。再分别以125和175μmol／LAdo灌流,机能曲线进一步向左上方移位,PS、TP和SP的变化均呈明显的剂量依赖性。（2）用腺苷选择性A1受体拮抗剂8－cyclopentyl－1,3－dipropylxanthine（0．134mmol／L）预处理后,Ado的上述效应即被阻断。（3）先给予KATP通道阻断剂格列苯脲（10μmol／L）亦可取消腔苷对窦神经传入放电的影响。结果表明,在体隔离灌流大鼠颈动脉窦区条件下,Ado对颈动脉窦压力感受器活动有易化作用,此作用似与腺苷A1受体介导的KATP通道开放有关。     

缓激肽抑制麻醉大鼠颈动脉窦压力感受器反射

在36只隔离灌流左侧颈动脉窦区的麻醉大鼠上观察了缓激肽(bradykinin,BK)对颈动脉窦压力感受器反射的影响.结果如下:(1)以BK (1.0μmol/L)隔离灌流大鼠颈动脉窦区时,压力感受器机能曲线向右上方移位,曲线的最大斜率(peak slope,PS)由0.44±0.14降至0.31±0.01(P<0.01),反射性血压下降幅度(reflex decrease,RD)由6.85±0.18 kPa降至4.46±0.16 kPa (P<0.01),阈压(TP)由7.76±0.20增至10.04±0.09kPa (P<0.05),其中RD,PS和TP的变化呈明显的剂量依赖性.(2)用环氧酶抑制剂消炎痛(indomethacin,10 μmol/L)预处理后,对BK (1.0μmol/L)抑制压力感受器的作用无影响; (3)预先灌流NO合酶阻断剂(L-NAME,100μmol/L),则可完全消除BK (1.0μmol/L)对压力感受器反射的抑制效应; (4)预先给予转换酶抑制剂(captopril,20μmol/L),可加强BK对压力感受器反射的抑制作用.以上结果表明:BK对大鼠颈动脉窦压力感受器反射有抑制作用,此作用系BK引起血管内皮细胞生成NO所致.     

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.