体外培养的血管内皮细胞低氧低糖损伤后tPA、PAI-1表达变化

目的：观察体外培养的血管内皮细胞低氧低糖损伤后组织型纤溶酶原激活剂(tPA)、Ⅰ型纤溶酶原激活物抑制因子(PAI-1)表达变化，探讨脑缺血后纤溶系统的变化及机制。材料和方法：制备体外内皮细胞低氧低糖损伤模型，利用HE染色、免疫细胞化学染色观察tPA、PAI-1表达变化。结果：低氧低糖损伤后，tPA、PAI-1表达均明显增强。结论：成功制备体外内皮细胞低氧低糖损伤模型。内皮细胞低氧低糖损伤可以诱导tPA、PAI-1表达增多，进一步说明脑缺血损伤后tPA、PAI-1表达增加并参与损伤过程。     

蚯蚓蛋白激酶对体内纤溶活性的增强作用研究

目的：探讨蚯蚓蛋白激酶制剂（LK）的纤溶增强作用。方法：采用静脉给药方法，观察LK对SD大鼠纤溶激活因子t-PA及其抑制物PAI-1的急性作用。结果：给药后，PAI-1活性被显著抑制（P<0.01），t-PA活性则明显增强（P<0.01）。剂量1200 U/kg体重的LK，其增强t-PA作用显著大于600U/kg体重剂量LK（P<0.05）。此外，体外观察表明:LK具有明显的激活纤溶酶原（Plg）作用，且有量-效关系，具有一定的浓度依赖性（1.56-25 kU/L）。结论：结果表明，LK具备增强纤溶的特性，静脉给药作用快速而肯定。     

新生大鼠缺氧缺血性脑损伤tPA、PAI-1表达的动态变化

目的:观察新生大鼠缺氧缺血性脑损伤(HIBD)中组织型纤溶酶原激活物(tPA)和1型纤溶酶原激活物抑制剂(PAI-1)表达变化的规律,探讨纤溶系统在缺氧缺血性脑损伤中的作用。方法:7日龄SD新生大鼠96只,随机分为2组:缺氧缺血性脑损伤组和假手术组。两组动物模型制备成功后3、6、12、24、36、48、72、96小时断头取脑,应用免疫组织化学及原位杂交方法检测缺氧缺血性脑损伤不同时间点t-PA、PAI-1表达的变化。结果:假手术组新生大鼠各脑区均有tPA、PAI-1蛋白及mRNA的弱表达,缺氧缺血性脑损伤组不同时间点t-PA、PAI-1二者表达呈不同的动态变化:tPA蛋白及mRNA 3小时开始表达增强,主要见于皮质和海马,神经元表达明显,血管表达较弱,48小时神经元及微血管内皮表达明显增强,72小时神经元表达明显减弱,微血管内皮见有明显阳性表达,之后表达减弱,3～96小时各时间点阳性着色神经元数目显著高于假手术组;PAI-1蛋白及mRNA 12小时表达有所增强,神经元和微血管内皮表达增多,72小时达高峰,12～96小时各时间点阳性着色神经元数目显著高于假手术组。结论:tPA和PAI-1参与HIBD的发病机制。     

Changes in von Willebrand factor and fibrinolysis following a post-exercise cool-down

The purpose of this study was to determine the effect of a post-exercise active cool-down on von Willebrand factor and fibrinolysis. Ten subjects performed two maximal oxygen uptake (O_2max) tests followed by a 10-min passive (PC) or an active (AC) cool-down. Blood samples were obtained pre-exercise, post-exercise, post-PC/AC, and 1 h post-exercise and analyzed for von Willebrand factor antigen (vWf:Ag), tissue plasminogen activator (tPA) antigen and activity and plasminogen activator inhibitor-1 (PAI-1) activity. Data were analyzed using repeated measures analysis of variance. No significant differences were found between O_2max tests for treadmill time, O_2max, respiratory exchange ratio, maximal heart rate, or maximal blood lactate concentration. vWf:Ag was significantly elevated (P<0.05) following PC [198.4 (18.3)% normal] versus AC [174.5 (15.6)% normal] and remained elevated 1-h post-exercise [179.4 (16.4)% normal for PC vs 158.6 (13.8)% normal for AC]. There were no differences between tests for tPA or PAI-1 activity, although tPA antigen was significantly elevated following PC versus AC (P <0.05). Following the cool-down, hematocrit was higher (P <0.05) for the PC test [48.90 (0.36)] compared with AC [47.43 (0.51)]. An AC reduces post-exercise vWf:Ag and tPA antigen without affecting tPA or PAI-1 activity.     

冠状动脉介入治疗患者tPA、D-二聚体、FDP检测的临床应用

目的:动态观察冠心病患者冠状动脉介入(PCI)治疗前后血浆组织纤溶酶原激活物(tPA)、D-二聚体(D-D)、纤维蛋白(原)降解产物(FDP)含量。方法:用ELISA对60例冠心病患者PCI术前、术后即刻和术后5天以及40例非手术对照组上述指标进行检测和比较;并进行门诊随访分析。结果:冠心病患者术前tPA含量明显低于对照组(P<0.05),D-D、FDP含量明显高于对照组(P<0.05);PCI术后即刻tPA较术前明显降低(P<0.01),术后5天回升至术前水平,但仍比对照组明显降低(P<0.01);D-D、FDP含量术后即刻较术前明显升高(P<0.01),术后5天下降至与术前无明显差异,但仍高于对照组(P<0.01)。门诊随访31例PCI术后疗效稳定患者tPA、D-D、FDP均与对照组无显著性差异(P>0.05)。结论:PCI可能造成冠心病患者血管内膜损伤而导致机体纤溶功能短期降低。     

The transentorhinal cortex of the African green monkey: a combined light- and electron-microscopic study of calcium-binding protein containing neurons

The transentorhinal cortex (TEC) is a primate-specific transition zone between the entorhinal allocortex and the temporal isocortex. Neurons in the lamina pre-alpha of TEC are known to be the first to develop intraneuronal changes in the course of Alzheimer’s disease. In order to shed light on this important feature, we studied as yet unknown morphological and neurochemical characteristics of the TEC of the African green monkey (Cercopithecus aethiops sabaeus). Using light- and electron-microscopic immunocytochemistry, the distribution and morphology of neurons containing calcium-binding proteins were described and compared with those in the adjacent cortices. Light-microscopic analysis revealed that parvalbumin-containing neurons were distributed in all cortical layers. Calbindin-containing cells were fewer but also present in each layer. Calretinin-containing neurons were largely confined to the upper layers of the TEC. All three types of neuron showed pyramidal-like, multipolar and bipolar shapes; their dendrites were smooth or beaded. Ultrastructural studies revealed immunopositive somata with infolded nuclei and large amounts of cytoplasm. The somata were only sparsely innervated by symmetric synapses. Immunopositive dendrites were almost exclusively covered with immunonegative axon terminals establishing symmetric and asymmetric synapses. Immunopositive terminals established symmetric contacts with immunonegative dendrites and somata. Only occasionally, could synaptic contacts between immunopositive pre- and postsynaptic structures be observed. The comparison of neurons in the TEC and adjacent cortices revealed no striking differences. In summary, the morphological and neurochemical characteristics of TEC neurons as analyzed in our study do not provide an explanation for the early onset of neurodegenerative changes in the TEC. Accepted: 10 December 1999     

蚓激酶（普恩复）治疗脑梗塞时抗凝和纤溶变化的临床研究

目的：探讨蚓激酶（普恩复）治疗急性脑梗塞时抗凝和纤溶的变化。方法：随机选择31例脑梗塞例患者，服药前后对患者行神经功能缺失评分、血浆中KPTT、PT、FIB、t－PA、PAI、D－二聚体的测定，并与以丹参治疗的20例脑梗塞患者进行对照。结果：患者口服蚓激酶后（400mg，3次／日），KPTT明显延长（P＜0．05），FIB明显减少（P＜0．05），t－PA活性明显增强（P＜0．01），D－二聚体明显增加（P＜0．01），以上指标在对照组中治疗前后无明显变化（P＞0．05）。治疗组、对照组PT、PAI在用药前后均无明显变化（P＞0．05）。结论：蚓激酶治疗脑梗塞取得疗效与内凝血途径抑制、纤溶的激活有关。     

尼古丁对血管内皮细胞释放t-PA及PAI-1的影响

目的: 研究尼古丁对人脐静脉内皮细胞(HUVECs)释放组织型纤溶酶原激活物(t-PA)和纤溶酶原激活物抑制物-1(PAI-1)的影响。方法: HUVECs培养后接种于24孔培养板中,随机分为对照组及实验组,分别进行以下实验。(1)以0.1、1、10、100 μmol/L 尼古丁孵育HUVECs,12 h后收集各组上清液;(2)以100 μmol/L尼古丁与HUVECs孵育0、4、6、8、12 及24 h,收集各组上清液。采用ELISA法测定各组t-PA和PAI-1的浓度。结果: HUVECs与不同浓度尼古丁孵育12 h后,100 μmol/L尼古丁组PAI-1蛋白较对照组明显增加(P<0.01);0.1、1及10 μmol/L尼古丁组PAI-1蛋白与对照组比较,均无显著差异(均P>0.05);各浓度组t-PA蛋白与对照组比较,均无显著差异(均P>0.05)。HUVECs 与100 μmol/L的尼古丁分别孵育4 、6 、8 、12 及24 h,各组PAI-1蛋白均较对照组明显升高(P<0.05),且其升高呈时间依赖性;各组t-PA与对照组比较,均无显著差异(均P>0.05)。结论: 尼古丁可抑制HUVECs的纤溶活性,对内皮细胞具有损伤作用。     

慢性肾脏疾病血清和尿液纤溶活性物质的改变及临床意义

目的探讨慢性肾脏疾病血清和尿液纤溶活性物质的改变及其临床意义。方法选择38例慢性肾小球肾炎(CGN),28例肾病综合征(NS),36例非透析治疗的慢性肾功能不全(CRF)和20例正常对照作为研究对象,应用ELISA法检测血清和尿液中组织型纤溶酶原激活剂(t-PA)和纤溶酶原激活物抑制剂-1(PAI-1)的浓度,同时分析尿中t-PA和PAI-1的水平与血t-PA、PAI-1、血肌酐和24h尿蛋白总量之间相关性。结果慢性肾脏疾病出现血清t-PA、PAI-1升高,尿液t-PA、PAI-1降低,其中尿液t-PA、PAI-1的改变独立于血清,不受血肌酐和24h尿蛋白定量的影响。结论慢性肾脏疾病患者存在纤溶活性物质的异常,其中尿液纤溶活性物质的改变可反应肾脏内皮细胞损伤。     

Delayed neuronal cell death and microglial cell reactivity in the CA1 region of the rat hippocampus in the cardiac arrest model

Morphological changes in the CA1 region of the hippocampus in the rat cardiac arrest model were studied with the in situ nick-end labeling (TUNEL) method and light and electron microscopy. The TUNEL-positive pyramidal cells first appeared on day 1, increased in number with time, and reached a peak at 7 days after recirculation. At the ultrastructural level, cell shrinkage, nuclear fragmentation, and an increased number of atuophagic vacuoles of the pyramidal cells were observed in the CA1 region. The brief ischemia activates the microglial cells in the CA1 region, and these cells were found to increase in number with time. The microglial cells were seen to adhere to degenerating pyramidal cells and to phagocytose the apoptotic neurons selectively.     

黄腐酸钠对糖尿病大鼠视网膜病变的作用

目的 :探讨黄腐酸钠对糖尿病大鼠视网膜病变 (DR)的治疗作用及其机制。方法 :对佐菌素诱导的糖尿病大鼠早期给予 0 .5 %黄腐酸钠 3 0mg/kg皮下注射 ,1次 /日 ,共 6个月。利用光镜和透射电镜观察其视网膜组织的形态改变 ,同时检测血浆纤溶酶原激活剂 (t PA)、纤溶酶原激活剂抑制物 (PAI 1)活性及循环血中粒细胞表面抗原CD11a、CD11b。结果 :(1)黄腐酸钠治疗组视网膜组织光镜下及超微结构变化较病变组大鼠有明显改善 ,毛细血管基底膜的增厚明显减轻 (P <0 .0 1)。 (2 )治疗组t PA、PAI 1活性的改变较病变组得以纠正 (P <0 .0 1)而接近于正常对照组水平 (P <0 .0 5 )。基底膜厚度与血浆t PA活性呈显著负相关。 (3 )治疗组CD11a、CD11b的表达受到抑制 (P <0 .0 5 )。结论 :黄腐酸钠对DR的进展有一定的抑制作用。此作用可能与维持血浆t PA、PAI 1平衡而改善纤溶活性 ,减少白细胞粘附有关。     

睾酮对人血管内皮细胞纤溶活性影响及机制

目的：观察睾酮对人血管内皮细胞分泌纤溶酶原激活物（tPA）、纤溶酶原激活物抑制物1（PAI-1）的影响及其机制。方法： 将体外培养的人血管内皮细胞（HUVEC）分为5个浓度睾酮组及单纯培养基对照组，MTT实验观察睾酮对细胞生长及活性影响。ELISA 法测各组tPA、 PAI-1含量。用雄激素受体拮抗剂(flutamide)预处理细胞后重复实验。结果： 生理及略低于生理剂量睾酮（3×10-10 mol/L-3×10-8 mol/L）可明显促进tPA 分泌（P＜0.01）；而大剂量则使tPA 含量明显减少（P＜0.01）。各睾酮组PAI-1含量均明显低于对照组（P＜0.05）。Flutamide 能有效消除睾酮的上述作用。结论： 生理浓度睾酮通过雄激素受体促进tPA分泌，降低PAI-1浓度而增强纤溶系统活性，有利于防止血栓性疾病的发生。     

The effect of different exercise intensities on the fibrinolytic system

Summary The effects of moderate 30-min cycle ergometer exercise (aerobic metabolism) followed by short-term exercise at maximal capacity (anaerobic metabolism) on fibrinolytic activity were investigated in ten female and ten male healthy, untrained subjects. The following parameters of fibrinolytic activity were measured initially (t ₀), at the end of the aerobic phase (t ₁), at the end of the anaerobic phase (t ₂) and after a 30-min recovery period (t3): tissue plasminogen activator (PA_t) activity, PA_t concentration, plasminogen activator inhibitor (PA_i) activity, and D-Dimer concentration. Moderate long-term exercise caused a slight but significant increase in PA_t concentration and PA_t activity (t ₁; P<0.01), whereas short-term exercise at maximal capacity (t ₂) produced a substantial elevation in both these parameters (P<0.01). This would suggest that PAt was not inhibited totally by PA_i which would itself seem to be consumed during exercise. In addition, a slight exercise intensity-dependent increase in D-Dimer concentration was measured — circumstancial evidence not only for elevated fibrinolytic potential, but also for an actual increase in fibrin degradation (t ₂: P<0.01). After t ₃ both PA_t activity and D-Dimer concentration were still slightly but significantly increased. The results obtained in the tests of fibrinolytic activity showed no significant difference between the men and the women. It would seem that the release of PA_t is more markedly stimulated by short-term intense physical exercise than by long-term moderate exercise and actually causes increased fibrin degradation.     

Changes in the fibrinolytic system associated with physical conditioning

Summary The effects of physical conditioning on plasma fibrinolytic activity were studied in two groups of subjects. Volunteers not engaged in any sport were compared with individuals having been subjected to aerobic conditioning (middle-distance runners, defined as men running more than 80 km per week). Plasma concentrations of the different components of the fibrinolytic system were evaluated before and immediately after a maximal effort treadmill protocol. Comparison of the resting parameters revealed that under basal conditions for plasma concentrations of plasminogen, fibrinogen, 2-antiplasmin, protein C and protein S there were no differences between the two groups. Concentrations of the fibrin degradation products (FbDP) and fibrinogen degradation products (FgDP) were significantly higher in the runners than in the control group, indicating an increased fibrinolytic potential that seemed to be a consequence of the reduced formation of tissue plasminogen activator-plasminogen activator inhibitor (t-PA-PAI) complexes. Acute maximal exercise resulted in pronounced fibrinolysis, evidenced by the elevation of FbDP and FgDP concentrations, in both groups of subjects. The acceleration of the fibrinolytic activity was larger in conditioned individuals, which could be accounted for by a higher t-PA release and reduced formation of t-PA-PAI complexes when compared to the untrained subjects.     

Delayed neuronal death following perinatal asphyxia in rat

 The consequences of perinatal asphyxia on the rat brain were studied 80 min to 8 days after birth with hematoxylin-eosin and in situ DNA double-strand-breaks labeling histochemistry. Asphyxia was induced by immersing fetus-containing uterus horns, removed from ready-to-deliver Sprague-Dawley rats, in a water bath at 37°C for various time periods (0–22 min). Spontaneous- and cesarean-delivered pups were used as controls. Perinatal asphyxia led to a decrease in the rate of survival, depending upon the length of the insult. No gross morphological changes could be seen in the brain of either control or asphyctic pups at any of the studied time points after delivery. However, in all groups, nuclear chromatin fragmentation, corresponding to in situ detection of DNA fragmentation, was observed at different stages. Nuclear fragmentation in control pups showed a specific distribution that appeared to be related to brain maturation, thus indicating programmed cell death. A progressive and delayed increase in nuclear fragmentation was found in asphyctic pups, which was dependent upon the length of the perinatal insult. The most evident effect was seen in frontal cortex, striatum, and cerebellum at postnatal day 8, although changes were also found in ventral-posterior thalamus, at days 1 and 2. Thus, nuclear chromatin fragmentation in asphyctic pups indicates a delayed post-asphyctic neuronal death. The absence of signs of inflammation or necrosis suggests that delayed neuronal cell death following perinatal asphyxia is an active, apoptosis-like phenomenon. Received: 16 August 1996 / Accepted: 6 December 1996     

The antioxidant melatonin reduces cortical neuronal death after intrastriatal injection of kainate in the rat

 The anti-excitotoxic efficacy of the pineal hormone melatonin was investigated in kainate-injured brains of rats. Kainate (a glutamate-receptor agonist, 2.5 nmol in 1 μl) was directly injected to unilateral striatum. Melatonin (10 mg/kg) was administrated intraperitoneally 1 h before and 1, 3, and 5 h after intrastriatal kainate injection in adult Sprague-Dawley rats. Three days after kainate injection, a significant neuronal damage was found, as determined by Nissl staining and the TUNEL method, not only in the injected striatum, but also in the ipsilateral neighboring cortex. The kainate-induced cortical apoptotic neuronal death was significantly attenuated by treatment with melatonin compared with the vehicle control group. However, no detectable changes were observed in the contralateral side of the brain in either vehicle- or melatonin-treated rats. Moreover, the biochemical results indicated that kainate can indeed induce oxidative stress, such as a decrease in the content of total glutathione (GSH), oxidized glutathione (GSSG), and an increase in the ratio of GSSG/GSH in the striatum and cortex compared with the contralateral brain regions. In the kainate-injected striatum, melatonin did not reduce the oxidative stress, but in the neighborhood of injected area-cortex, kainate-induced oxidative stress was significantly reduced by melatonin. Enhancement of glutathione-peroxidase activity was induced by intrastriatal kainate injection, not only in the cortical area of control and melatonin-treated rats, but also in striatum of control rats. However, a large elevation was found in the melatonin-treated cortex. Taking the morphological and biochemical data together, the present results suggest that melatonin functions as an antioxidant by upregulating the glutathione antioxidative defense system, thereby reducing neuronal death caused by excitotoxicity and preventing the kainate-induced damage from spreading to adjacent brain regions. Received: 16 December 1997 / Accepted: 30 July 1998     

Prognostic relevance of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitors PAI-1 and PAI-2 in gastric cancer

Expression of urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2) was evaluated in 125 surgically resected gastric cancers by immunohistochemical analysis. Tissue was stained immunohistochemically with a monoclonal antibody against human uPA and monoclonal antibodies against human PAI-1 and PAI-2. In addition, DNA ploidy patterns were determined by cytofluorometer after staining with propidium iodide. We found that 82 (66%) of the 125 gastric cancers expressed uPA as diffuse cytoplasmic staining, as intensely outlined luminal borders. PAI-1 expression was observed in 62 (50%) of 125 gastric cancer as a fine, diffuse and granular pattern in the cytoplasm. PAI-2 expression was observed in 65 (52%) of the 125 gastric cancers as a diffuse cytoplasmic staining. uPA-positive tumours showed a higher incidence of infiltration, lymph node metastasis and peritoneal dissemination than uPA-negative ones. Patients with uPA-positive tumours proved to have a significantly poorer prognosis than those with negative ones. PAI-1-negative tumours showed a higher incidence of liver metastasis and carried a poorer prognosis than PAI-1-positive ones. There was no significant correlation between uPA or PAI-1 expression and DNA ploidy patterns. Conversely, there was no significant relationship between PAI-2 expression and clinicopathological parameters and prognosis. According to the expression of uPA and PAI-1 status, groups of 19 uPA(–)/PAI-1(–), 44 uPA(+)/PAI-1(–), 23 uPA(–)/PAI-1(+) and 39 uPA(+)/PAI-1(+) were subdivided. Tumours with UPA(+)/PAI-1(–) had a significantly higher incidence of liver metastasis, lymph node metastasis and serosal invasion than the other groups of tumours. Patients with uPA(+)/PAI-1(–) tumours had a significantly poorer prognosis than those with uPA(–)/PAI-1(+) tumours. These results indicate that uPA expression is a useful biological prognostic indicator, and that uPA and PAI-1 may play an important part in the tumour progression and metastasis in gastric cancer.     

锡类散凝胶对兔输液性静脉炎治疗效果的初步观察

目的探讨锡类散凝胶对兔实验性输液性静脉炎的治疗效果及可能机制。方法将大白兔随机分为对照组、静脉炎组和锡类散治疗组，每组20只。静脉炎组在耳缘静脉注射甘露醇构建实验眭输液性静脉炎动物模型，对照组以生理盐水替代甘露醇，治疗组在造模前经锡类散预处理；在造模后相应的时间点检测兔血浆中TT（凝血酶时间）、PT（凝血酶原时间）、APTT（活化部分凝血酶时间）、PAI-1（I型纤溶酶原激活物抑制因子）和t—PA（组织型纤溶酶原激活剂）含量，并作病理学检查及评分，最后进行统计分析。结果治疗组与静脉炎组相比较（P〈0．05），能明显纠正因甘露醇而造成的高凝状态，有效降低血清t—PA水平及减轻输液静脉损害；而PAI—1含量在三组之间没有统计学差异（P〉0．05）。结论锡类散凝胶能有效改善甘露醇所致的输液胜静脉炎损害，其机制可能通过抑制血清t—PA升高而发挥治疗作用。     

Effects of mesaconitine on [3H]noradrenaline uptake and neuronal excitability in rat hippocampus

Mesaconitine, one of the main alkaloids contained in Aconiti tubers, is a centrally acting analgesic without affinity to opioid receptors. It has been reported that the antinociception is due to an interaction with the noradrenergic system. In the present study, the effect of mesaconitine on the uptake of noradrenaline and on neuronal activity was examined in rat hippocampus. Experiments were performed as a tudy of [³H]noradrenaline uptake into rat hippocampal synaptosomes. Mesoconitine inhibited [³H]noradrenaline uptake in a concentration-dependent manner with a K _i of 111.95±18 nM. In a further series of experiments, the effects of mesaconitine on the extracellularly recorded population spike were investigated in rat hippocampal slices. At a concentration of 10 nM, mesaconitine increased the amplitude of the postsynaptic population spike by 31.10%±6.7% of control and elicited one or two additional spikes. The presynaptic fiber spike and the field excitatory postsynaptic potential were not affected by this alkaloid. The enhancement of neuronal activity was abolished by 1 μM propranolol as well as by 1 μM timolol. It is concluded that mesoconitine increased the excitability in rat hippocampal pyramidal cells by an involvement of the noradrenergic system, with at least one mechanism being inhibition of noradrenaline uptake leading to an enhanced extraneuronal noradrenaline level. Received: 25 August 1997 / Accepted: 3 March 1998     

登革2型病毒调控血管内皮细胞纤溶系统相关蛋白的表达

目的观察登革2型病毒（DV2）对人脐静脉血管内皮细胞（HUVEC）表达组织纤溶酶原激活物（tPA）和纤溶酶原激活物抑制物1（PAI-1）的影响。方法应用胰酶消化分离HUVEC并进行传代培养，用生长良好的第2．3代细胞进行试验。用cell counting kit-8（CCK-8）测定DV2感染后细胞活性变化；发色底物法测定感染DV2组和对照组培养液中tPA、PAI-1活性；RT-PCR检测细胞内tPA和PAI-1 mRNA水平。结果DV2感染对细胞活力的影响与对照组相比差异无统计学意义。感染DV2组培养液中tPA活性在12～72h显著升高（P〈0．05）；DV2诱导HUVEC表达tPA mRNA的水平显著上调，12h达到峰值，以后渐降，72h mRNA表达水平仍高于对照组（P〈0．01）。而DV2感染组培养液中PAI-1活性和PAI-1 mRNA的表达与对照组比较差异无统计学意义（P〉0．05）。结论DV2感染可显著上调HUVEC的tPA mRNA转录，增强内皮细胞tPA蛋白的分泌，而不影响PAI-1 mRNA的转录或改变内皮细胞PAI-1的分泌。结果提示DV2可活化但并不损伤内皮细胞，诱发内皮细胞增强表达纤溶酶原激活物而致使纤溶系统失衡，引起纤溶亢进，这可能是诱发DHF／DSS患者急性期出血、低血容量性休克等体征的主要因素之一。