Behavior of the dengue virus in solution

The dengue virus consists of four antigenically related but distinct viruses, termed Dengue virus 1-4 (DEN 1-4). We have established that the dengue virus loses infectivity over time in solution in an exponentially declining manner. The four strains examined (one from each serotype) have half-lives that range from 2.5 to 7.5 hr in defined medium. The half-life is temperature and pH-dependent and is affected by the nature of the host cell in which it is produced, but is not dependent upon the presence of either Mg(2+) ions or chelating agents. Electron microscopy (EM) of solutions of the dengue virus show almost complete virus aggregation after 24 hr at room temperature, while RT-PCR shows an intact RNA genome. These results show that the solution environment of the dengue virus is an important determinant of dengue virus infectivity.     

体外血栓形成后血液的流变性变化及体外血栓形成试验的规范化操作

目的:观察体外模拟血栓形成后剩余血液的流变学变化,并探讨体外血栓形成试验的规范化操作。方法:采用30例健康人静脉血液,一部分抗凝后测定血液流变学指标和血细胞计数,另一部分不抗凝,于Chandler环内模拟血栓形成后,再测定剩余血液的血细胞计数及流变学指标,包括血液表观粘度、红细胞聚集指数、红细胞变形指数、血小板最大聚集率、血小板粘附率和血浆纤维蛋白原含量等。结果:体外模拟血栓形成后剩余血液的表观粘度,血小板计数、白细胞计数及纤维蛋白原含量均显著降低(P<0.01);血小板粘附率、最大聚集率也显著降低(P<0.01);但红细胞计数、压积和变形指数变化不明显(P>0.05)。结论:模拟血栓形成后剩余血液的流变性发生了显著变化,尤以血小板数量、血小板聚集性和粘附性以及血浆纤维蛋白原含量的变化更加突出。规范体外血栓形成试验的操作方法,有利于提高该试验的准确性和可靠性。     

噻氯匹定对脑梗塞患者血小板聚集功能和血液流变学的影响

以50例脑梗塞为观察组，45例健康人为对照组，观察噻氯匹定对脑梗塞血小板聚集功能和血液流变学的影响。（1）治疗前，观察组血小板聚集率（PAR）非常显著地高于对照组（P＜0.01），（2）治疗后，观察组PAR非常显著地低干治疗前（P＜0.01），与对照组比较已无显著性差异（P＞0．05），（3）观察组各亚组治疗后PAR大多非常显著地低于治疗前（P＜0．01）。（4）观察组治疗前后血液流变学指标无显著性变化（P＞0．05），（5）神经功能缺损评分：治疗前15．8±0．98；治疗后8．2±5.4，差异有非常显著意义（P＜0．01）。     

Aggregates of modified low-density lipoproteins induce lipid accumulation in intimal cells of the human aorta in vitro

Institute of Experimental Cardiology, All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Smirnov.) Translated from Byulleten's Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 7, pp. 34–36, July, 1990.     

Tourmaline纤维抑制高黏血症家兔血小板聚集的实验研究

目的 研究Tourmaline纤维对高黏血症家兔血小板聚集的影响。方法 用静脉注射高分子右旋糖酐(MW>140000)的方法复制高黏血症家兔模型,测定应用Tourmaline纤维(实验组,n=6)及对照纤维(对照组,n=6)前后血小板聚集率(1分钟聚集率A1和最大聚集率Amax)的变化。并分析TXA_2水平的变化与血小板Amax间的相关关系。结果 与对照组比,实验组高黏血症家兔在应用Tourmaline纤维后6、12h血小板A1和Amax明显降低,与应用前比,差异有显著意义(P<0.05),12h时TXA_2降低与A-max间呈显著负相关(r=-0.94),24h无显著差异(与对照组比)。结论 使用Tourmaline纤维6h和12h后,高黏血症家兔的血小板聚集明显被抑制,此作用与血浆TXA_2的降低相关。     

Anti-tumor immunoglobulin M increases lung metastasis in an experimental model of malignant melanoma

Cancer metastasis involves distinct steps that depend on complicated tumor–host interactions. The hematogenous dissemination of tumor cells may be facilitated by factors that promote the arrest and adherence of cancer cells in capillaries. We examined whether anti-tumor monoclonal immunoglobulin M (IgM) antibodies promoted the hematogenous dissemination of B16 melanoma cells in syngeneic mice. IgM monoclonal antibodies were generated that selectively bind to B16 melanoma cells as compared to syngeneic fibroblasts, lymphocytes or Lewis lung carcinoma cells. Incubation of B16-BL6 or B16-F0 melanoma cells with these IgM anti-tumor antibodies significantly increased the number of lung colonies as compared with control antibodies. Moreover, intraperitoneal injection of specific antibody also significantly increased lung colonization. All anti-tumor antibodies promoted the aggregation of B16 melanoma cells. A chemically generated immunoglobulin G (IgG)-like fragment of an anti-tumor IgM antibody displayed greatly reduced tumor aggregation and, in contrast to intact IgM, did not significantly increase lung colonization of B16 melanoma cells. Neither intact IgM nor the IgG-like fragment enhanced the in vitro invasiveness of B16 melanoma cells across Matrigel-coated membranes. Our results, therefore, suggest that besides their beneficial anti-tumor effects, anti-tumor IgM antibodies may also promote the hematogenous dissemination of cancer cells. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of some calcium antagonists on aggregation by adrenalin and serotonin and on α-adrenoceptor radioligand binding in human platelets

The inhibitory effects of verapamil, nifedipine and diltiazem, representatives of different classes of calcium antagonists, were studied on aggregation of human platelets induced by adrenalin and serotonin (5-HT). For references, the α-adrenoceptor-antagonists phentolamine (α₁ and α₂) and rauwolscine (α₂), and the s-HT₂-receptor-antagonist ketanserin were included. Verapamil in the concentration range 10^-6- 10^-4 M inhibited both adrenalin- and serotonin-induced aggregation in a concentration-dependent manner, whereas nifedipine and diltiazem had little or no effect. Phentolamine and rauwolscine were clearly weaker than verapamil as antagonists of serotonin, and ketanserin lacked effect on adrenalin-induced aggregation. Binding studies with [³H]dihydro-α-ergocryptine and [³H]rauwolscine on human platelet membranes showed equal numbers of binding sites, suggesting that only α₂-adrenoceptors were present. In the same concentration range as inhibition of aggregation was obtained, verapamil inhibited binding of either radioligand. Nifedipine, diltiazem and 5-HT were all poor inhibitors of radioligand binding. The results suggest that verapamil at high concentrations not only has α-adrenoceptor antagonistic properties but also exerts 5-HT-receptor blocking effects. This was not found with the other calcium channel blockers examined (nifedipine, diltiazem).     

心脑血管病患者微血栓与D－2聚体、血小板聚集的相互关系

观察２０例急性脑梗塞，３０例冠心病在微循环中微血栓的变化，同时检测血小板聚集率、Ｄ－２聚体。结果表明微血栓阳性组血小板聚集率、Ｄ－２聚体均高于微血栓阴性组。治疗后二组血小板聚集、Ｄ－２聚体明显减少。提示微血栓、Ｄ－２聚体及血小板聚集率可作为评定冠心病、脑梗塞病情变化的一种指标     

合成消旋丹参素及其衍生物对血小板聚集性和cAMP含量的影响

合成消旋丹参素(简称合成丹参素)及其衍生物(BLA、BLE)在体外实验和体内静脉注射时,对ADP诱导的家兔和大鼠血小板聚集性均有明显的抑制作用。BLK和BLE有较强的促进血小板解聚作用,而合成丹参素较弱。合成丹参索、BLA和BLE在体外实验时,无升高血小板内cAMP作用,反使其cAMP含量下降。提示合成丹参素及其衍生物对血小板功能的作用,不是通过提高cAMP水平;推测可能和抑制血栓素A_2(TXA_2)合成酶有关。