人vWF-A1区蛋白的表达及其对血小板聚集的抑制作用

目的:进一步研究血栓形成的机制,开发抗血栓药物。方法: 应用基因重组技术在大肠杆菌中表达人vWF-A1区蛋白,经过纯化、复性,获得重组蛋白(rvWF-A1),同时用流式细胞术检测rvWF-A1与血小板膜糖蛋白血小板膜糖蛋白(glycoprotein, GP)Ib的结合能力,应用血小板聚集仪测定rvWF-A1对瑞斯托霉素(ristocetin)诱导的血小板聚集抑制作用。结果: 重组表达载体pQE-31-vWF-A1在大肠杆菌M15中得到高效表达,表达的重组蛋白量占菌体总蛋白的30%,Ni-NTA agrose柱纯化后,其纯度为95%,经复性的rvWF-A1蛋白具有良好的生物学活性。它可与血小板模糖蛋白血小板膜糖蛋白GPIb结合,阳性率为78.6%;它可以抑制ristocetin诱导的血小板聚集,抑制率为84.7%。结论: 在原核细胞中可以成功地高效表达人vWF-A1区蛋白,该重组蛋白有可能开发为有效的抗血栓药物。     

[H]Paroxetine binding in human platelets in relation to age and sex

The binding of [³H]paroxetine to serotonin uptake sites in human platelets from 47 individuals between 15 and 95 years of age was investigated. There were no significant age-related changes in maximal binding capacity (B_max) or apparent binding affinity (K_d). There were no significant differences in binding between males (n = 19) and females (n = 28).     

中性粒细胞对洗涤血小板聚集功能的影响

目的:观察非激活或激活的中性粒细胞(PMN)对洗涤血小板聚集功能的影响。方法:采用Born方法测定血小板聚集功能。结果:非激活的PMN(5×10⁹cells/L)上清液对ADP和花生四烯酸(AA)诱导的血小板聚集具有显著抑制作用,阿司匹林可增强这种抑制作用;肉豆寇佛波醇(fMLP)及血小板活化因子(PAF)激活的PMN悬液或其上清液均能活化血小板聚集,且PMN悬液的诱聚作用比其上清液更强;阿司匹林对fMLP或PAF激活的PMN悬液或其上清液均无明显抑制作用。结论:不同状态(非激活或激活状态)的PMN对正常血小板的反应性表现出完全相反的作用,即非激活的PMN抑制血小板反应性,而激活的PMN则具有促血小板活化聚集作用。     

HPA polymorphism in sub-Saharan African populations: Beninese, Cameroonians, Congolese, and Pygmies

The frequency of human platelet antigen-1 (HPA-1) to HPA-11w (excluding HPA-8w) and HPA-15 systems was studied in four sub-Saharan populations: Beninese, Congolese (Democratic Republic of Congo Kinshasa), Cameroonians, and Aka pygmies (Central African Republic). No report of HPA prevalence has previously been published concerning these populations which are characterized by the highest HPA-2b gene frequencies of any reported to date (Aka 0.393, Benin 0.292, Cameroon 0.237, and Congo 0.224) and at lesser degree HPA-5b (Aka 0.405, Congo 0.268, Cameroon 0.254, and Benin 0.182). This study is of great importance (i) particularly in the context of the diversity caused by the population migrations, we may observe today in our hospitals (ii) to confirm that the Pygmy population with distinctive frequencies (absence of the HPA-1b, HPA-2b, and HPA-5b highest frequencies) is an isolated population.     

Platelet monoamine oxidase activity in Down's syndrome

The activity of platelet monoamine oxidase in Down's syndrome cases was significantly lower than that of controls. This difference was found for both males and females, and with tyramine, tryptamine and β-phenethylamine as substrate. The K_m values of the monoamine oxidase towards tryptamine as substrate from controls and Down's syndrome patients were similar.     

IL-6和IL-11对脐血CD34+细胞诱导分化为巨核细胞的影响

目的： 探讨白细胞介素－6(IL-6)和白细胞介素－11(IL-11)对脐血CD34+细胞诱导分化为巨核细胞及其产生血小板的影响。方法: 采用免疫磁珠法(MACS)分选8例健康产妇足月顺产的胎儿脐血中CD34+细胞，以含血小板生成素（TPO 50 μg/L）、白细胞介素-3（IL-3 10 μg/L）、干细胞因子（SCF 50 μg/L）的无血清培养基作为对照组，分别添加10 μg/L IL-6、IL-11、IL-6+IL-11作为实验组，培养14 d后观察结果。利用细胞计数仪检测单个核细胞数；流式细胞仪计数培养体系中的CD41+细胞和血小板；用倒置显微镜观察培养体系中的细胞生长情况；用显微镜和流式细胞仪观察凝血酶诱导后的血小板凝集情况。结果: 各实验组单个核细胞数与对照组无明显区别（P>0.05），而CD41+细胞和血小板数量明显多于对照组(P<0.05)。培养第14 d后倒置显微镜下可见实验组中血小板样颗粒物明显多于对照组，而且经凝血酶诱导后有明显血小板凝集。结论: IL-6和IL-11可诱导脐血中CD34+细胞分化为巨核细胞并产生功能性血小板。     

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).     

Quality validation of platelets obtained from the Haemonetics and Trima Accel automated blood-collection systems

BackgroundPlatelet transfusion is required to treat haemo-oncology or trauma patients. Platelet apheresis (PA) performed with apheresis equipment has increased rapidly in recent years. Leucocyte-reduced platelet apheresis (LRPA) can reduce the risk of platelet refractoriness and febrile nonhemolytic transfusion reactions (FNHTRs) for transfusion. Accordingly, this study aimed to investigate and compare the platelet metabolic and functional responses between PA performed with Haemonetics and LRPA performed with Trima Accel cell separator.MethodsThe qualities of platelets collected through PA and LRPA were evaluated in terms of visual appearance, morphology, platelet-aggregation changes, metabolic activities, and bacterium-screening test during 5-day storage. Statistical analyses included two-sample t-test and generalised estimating equation(GEE) method.ResultsDuring 5-day storage in LRPA, residual leucocytes were all <1.0×10⁶, and the parameters of platelet function were as follows: platelet aggregated to agonists such as adenosine 5′-diphosphate (ADP) and collagen, and the extent of shape change and pO₂ showed no statistically significant difference between PA and LRPA. The hypotonic shock reaction (HSR) on days 0, 1, and 3 were significantly higher in LRPA than in PA (71.78±6.92 vs. 64.10±7.42; P=0.002; 71.53±8.98 vs. 62.96±9.84; P=0.007; 68.05±7.28 vs. 57.76±6.80; P<0.0001, respectively). Values of mean platelet volume (MPV) were statistically larger in PA than in LRPA on days 0, 1, and 3. On day 5, the swirling score was higher in LRPA than in PA. The mean lactate levels had no statistically significant difference between PA and LRPA. Moreover, no growth was observed through bacterium-screening test conducted on 40 samples.ConclusionComparison of LRPA and PA products collected from the Trima Accel and Haemonetics automated blood-collection systems, respectively, revealed that both products possessed good platelet qualities even though additional processes are needed to reduce leucocytes. Furthermore, investigating the outcomes of other apheresis instruments with focus on the safety of donors, products, and recipients is necessary.