一氧化氮阿司匹林对血小板聚集功能的影响

目的研究一种能缓慢释放一氧化氮的新型阿司匹林（BPI-1096）对血小板聚集功能的影响。方法正常人富血小板血浆与药物在37℃条件下温育10min后，采用比浊法测定不同诱导荆作用下血小板聚集率。结果不同浓度条件下BPI-1096能够不同程度地降低由二磷酸腺苷、血小板活化因子、肾上腺素及瑞斯托霉素诱导的血小板聚集（P〈0．05），对花生四烯酸诱导的血小板聚集虽有降低但是无统计学意义；在相同浓度条件下BPI-1096与阿司匹林抑制血小板聚集率的作用无显著性差异；在不同浓度条件下BPI-1096对血小板聚集率不存在明显的浓度效应关系。结论BPI-1096作为一种新型的一氧化氮阿司匹林，能够显著抑制二磷酸腺苷、血小板活化因子、瑞斯托霉素及。肾上腺素等多种诱导条件下体外血小板聚集功能，作用强度与传统阿司匹林疗效相当，其对血小板的抑制作用强度无明显的浓度效应关系。     

野黄芩苷抗血小板活化效应的评价

目的评价野黄芩苷对血小板的聚集与活化的影响。方法在人洗涤血小板中进行血小板聚集实验,分别用胶原(1.00μg/ml)、U46619(0.30μM)、ADP(10.00μM)、凝血酶(0.04U/ml)作为诱导剂,对比在0.04mg/ml、0.10mg/ml、0.20mg/ml三种不同预孵浓度状态下野黄芩苷对血小板聚集的影响。并进一步研究三种不同浓度的野黄芩苷对血栓素类似物(U46619)引起的血小板纤维蛋白原结合的影响。结果胶原、U46619、ADP、凝血酶均可明显促进血小板聚集,而血小板预孵育野黄芩苷可以抑制诱导剂引起的聚集,并且抑制作用呈现浓度依赖关系。血小板预孵育野黄芩苷可以减少U46619引起的血小板纤维蛋白结合,并且抑制作用呈现浓度依赖关系。结论野黄芩苷可以抑制血小板的聚集和活化,很可能是通过阻断血栓素A2诱导血小板聚集的某一个中间环节产生作用。     

阿司匹林、肝素对血小板活化及表达CD40L的影响

目的探讨血小板活化与表达CD40L的关系以及阿司匹林、肝素对此过程的影响.方法体外分离健康人血小板,经不同浓度二磷酸腺苷(ADP)、凝血酶诱导后,应用流式细胞术测定血小板活化指标P选择素和炎性标志CD40L表达水平,观察二者随诱导时间延长的变化过程,并分析阿司匹林、普通肝素、低分子肝素对血小板活化及表达CD40L的影响.结果 ADP、凝血酶均呈浓度依赖方式增加血小板P选择素、CD40L表达,二者表达水平随诱导时间延长而同步增减,呈显著正相关(P<0.05).阿司匹林(2.5 μg/ml)对ADP(4 μmol/L)和凝血酶(1U/ml)诱导的血小板活化及CD40L表达无任何影响(P>0.05);普通肝素(2.5U/ml)和低分子肝素(2.5U/ml)单独或与阿司匹林合用,均能极显著地抑制凝血酶诱导的血小板活化及CD40L表达(P＜0.001),但对ADP的诱导过程无影响(P>0.05).结论炎性介质CD40L可表达在活化血小板表面,在多种诱导剂存在的情况下,阿司匹林及肝素能部分抑制血小板的活化及CD40L表达.     

达肝素钠对兔血小板功能的影响及阿司匹林和氯吡格雷的干预作用

目的 研究达肝素钠对兔血小板活化的影响以及阿司匹林和氯吡格雷的干预.方法　纯种新西兰家兔12只,给予阿司匹林或氯吡格雷或二者合用喂饲,静脉注射达肝素钠前及注射后20、30 min检测ADP、AA诱导的血小板聚集、血浆CD62P和vWF的水平.结果 应用达肝素钠后血小板聚集、CD62及vWF无明显增加;与基线水平比较,阿司匹林组加用氯吡格雷两药合用,静脉注射达肝素钠前(9.50±4.18 vs 2.67±1.63)及注射后20 min(10.50±3.21 vs 2.83±1.66)ADP 诱导的血小板聚集均明显降低.单用阿司匹林喂饲7 d,应用达肝素钠后血小板聚集增加(7.00±4.10 vs 12.50±4.04).结论 达肝素钠不会引起血小板激活;阿司匹林与达肝素钠合用增加血小板聚集;氯吡格雷与阿司匹林两药合用明显降低血小板聚集.     

野木瓜多糖对家兔血小板聚集的影响

目的研究野木瓜多糖(SCP)对血小板聚集的影响及可能机制。方法选择成年家兔30只,随机分为空白对照组、SCP 17 g/L组、SCP 34 g/L组、SCP 68 g/L组、阿司匹林组,每组6只。制备家兔富血小板及贫血小板血浆,用Born's比浊法检测17、34、68 g/LSCP对胶原、花生四烯酸(AA)、二磷酸腺苷(ADP)及凝血酶诱导的血小板聚集的影响。检测SCP对胶原诱导后血小板中5-羟色胺含量、肝素凝血酶凝固时间(HTCT)及对凝血酶作用后血小板释放丙二醛含量的影响。结果与空白对照组比较,不同浓度SCP组、阿司匹林组的胶原、ADP、凝血酶诱导的血小板聚集明显降低(P<0.05,P<0.01),SCP 1 7 g/L组AA诱导的血小板聚集无明显变化(P>0.05),SCP34 g/L组、SCP 68 g/L组、阿司匹林组AA诱导的血小板聚集明显降低(P<0.05,P<0.01)。与空白对照组比较,不同浓度SCP组丙二醛含量明显降低、HTCT延长,呈浓度依赖性(P<0.01),除SCP 1 7 g/L组外,其余各组5羟色胺明显降低,呈浓度依赖性(P<0.05,P<0.01)。结论 SCP可以抑制由胶原、ADP、AA和凝血酶诱导的血小板聚集,其机制与抑制血小板释放5-羟色胺、血小板因子Ⅳ及减少丙二醛生成有关。     

氯吡格雷对阿司匹林抵抗的影响及其与他汀类药物的相互作用

目的比较氯吡格雷联用不同种类的他汀类药物时血小板聚集率的差别,揭示其对氯吡格雷的抗血小板作用是否存在影响,明确氯吡格雷对阿司匹林抵抗的影响。方法将70例急性冠脉综合征(ACS)病人分为两组,阿司匹林组30例,入院后3d内口服阿司匹林300mg/d,后改为100mg/d至两周;联合用药组40例,阿司匹林服用如前,同时加用氯吡格雷75mg/d。于两周时采静脉血,应用比浊法分别测定二磷酸腺苷(ADP)和花生四烯酸(AA)诱导的血小板聚集率。又将联合用药组随机分为细胞色素氧化酶(CYP)3A4代谢的他汀组(A组,服阿托伐他汀10mg~40mg或辛伐他汀40mg或洛伐他汀40mg)和非CYP3A4代谢的他汀组(B组,服氟伐他汀80mg或普伐他汀20mg)各20例,两周时采静脉血测定血小板聚集率如前(仅观察ADP诱导的血小板聚集率)。结果联合用药组与阿司匹林组相比,两种不同诱导剂诱导的血小板平均聚集率均明显下降(P<0.05或P<0.01),其中以ADP诱导的血小板平均聚集率下降更显著,联合用药组阿司匹林抵抗(AR)与阿司匹林半抵抗(ASR)总发生率较单用阿司匹林组明显为低(P<0.05);CYP3A4代谢的他汀与非CYP3A4代谢的他汀组相比较,在与氯吡格雷联用时,对氯吡格雷抗血小板作用影响无统计学意义(P>0.05)。结论联用氯吡格雷可明显减少阿司匹林抵抗,从而减少不良心血管事件的发生。     

速效救心丸对大鼠血小板聚集率及环磷腺苷水平的影响

目的探讨速效救心丸对血小板聚集的作用及机制。方法采用比浊法测定速效救心丸、阿司匹林、阿魏酸哌嗪对二磷酸腺苷(ADP)、胶原和花生四烯酸(AA)诱导的大鼠血小板聚集率和环磷腺苷(cAMP)水平的影响。结果与空白组比较,速效救心丸中、高剂量组可显著抑制ADP、胶原、AA诱导大鼠的血小板聚集(P0.01);速效救心丸高剂量组对AA诱导的大鼠血小板聚集抑制作用较阿司匹林组好;速效救心丸可提高大鼠血小板内cAMP的含量(P0.05)。结论速效救心丸能够抑制大鼠ADP、胶原和AA诱导的血小板聚集,其机制可能通过增加cAMP的含量而发挥作用。     

沙库巴曲缬沙坦对血小板活化、动脉血栓形成的作用

目的 探索沙库巴曲缬沙坦对血小板活化、动脉血栓形成的作用。方法 通过血小板聚集、释放、P-选择素释放、整合素αⅡbβ3活化、铺展、栓块回缩分析等实验,检测体外孵育沙库巴曲缬沙坦对人血小板活化的作用,通过FeCl3损伤小鼠肠系膜动脉血栓实验分析沙库巴曲缬沙坦对体内动脉血栓形成的作用。结果 沙库巴曲缬沙坦浓度依赖地抑制了凝血酶、胶原、二磷酸腺苷诱导的人血小板聚集、释放,沙库巴曲缬沙坦抑制了P-选择素释放、整合素αⅡbβ3活化、铺展、栓块回缩,沙库巴曲缬沙坦抑制了小鼠体内动脉血栓的形成。结论 沙库巴曲缬沙坦具有抑制血小板活化、抗动脉血栓形成的作用。     

阿司匹林抑制老年冠心病患者血小板聚集的疗效观察

目的:观察阿司匹林治疗老年冠心病患者24周对血小板聚集功能的影响。方法:选择临床需要服用阿司匹林抗血小板治疗,且ADP诱导的血小板聚集率增高的老年冠心病患者122例,给予阿司匹林100mg口服24周。用药前及用药6、12、24周后分别测定血小板聚集率。结果:服用阿司匹林后,患者的血小板聚集率显著降低,6、12、24周测定血小板聚集率与基线比较均差异有统计学意义(均P<0.01),血小板聚集抑制率分别为-(21.13±21.66)%,-(29.25±21.67)%,-(22.87±21.92)%。12周的血小板聚集率较6周进一步下降,但24周较12周则明显升高,两个差值均差异有统计学意义(均P<0.05)。结论:阿司匹林可明显降低患者的血小板聚集功能,但抗血小板聚集作用在24周后较12周有明显下降。     

三七总苷对阿司匹林抵抗影响的临床观察

目的探讨三七总苷对阿司匹林抵抗（AR）病人的影响。方法选择接受阿司匹林治疗的病人318例,根据二磷酸腺苷（ADP）诱导血小板聚集率筛选出阿司匹林抵抗病人,按时间顺序分为两组。联合治疗组用三七总苷,每日3粒,加阿司匹林100mg/d;三七总苷组用三七总苷,每日3粒,疗程均为1个月。检查治疗前及治疗1个月后的血小板聚集率。结果318例病人中64例存在阿司匹林抵抗,占20.1%。联合治疗组与三七总苷组服药后1个月血小板聚集率分别为50.5%±11.7%,54.6%±10.3%,较治疗前均明显下降（P〈0.05）。结论三七总苷对ADP诱导血小板聚集率有一定的降低作用。     

Increase in density and accumulation of serotonin by human aging platelets

⁵¹Cr-labeled autologous platelets were infused into splenectomized subjects and the specific radioactivities of high-density (HD) and low-density (LD) platelet subpopulations were determined sequentially in postinfusion samples. A rapid decrease in the specific radioactivity of LD cohorts (T 1/2 = 2.5 days) was observed, but the specific radioactivity of HD platelets remained constant or increased slightly during the first 4 days and then gradually declined for the next 5 days. No experimental artifacts during the platelet-labeling steps that could account for these results were demonstrated. These findings confirm previous observations in eusplenic individuals and support the hypothesis that human LD platelets are, on the average, younger than HD platelets. LD platelets contain 33.8 ± 13.5 ng serotonin (5HT)/10⁸ platelets and HD platelets 76.8 ± 9.5 ng 5HT/10⁸ platelets (P < 0.001). Sequential measurements of 5HT in PRP platelets were performed during the recovery phase of thrombocytopenia following splenectomy in patients with idiopathic thrombocytopenic purpura (ITP), a condition associated with aging of platelets in circulation. Presplenectomy platelet 5HT was 17.7 ng/10⁸ platelets and on days 1, 6, and 12 after surgery it increased to 18.1, 37.8, and 61.0 ng/10⁸ platelets (n = 7). When three healthy volunteers were given aspirin (500 mg/day) for up to 15 days, no significant change in the 5HT content of circulating platelets was observed. If aspirin blocks, at least partially, the secretory process in vivo without interfering the 5HT uptake by the platelets, this finding stands against the possibility that a net depletion of 5HT occurs during the life-span of normal human platelets. The observation that human HD platelets, enriched with older cells, contain more 5HT than LD platelets taken together with the parallel increase in platelet 5HT and age during the recovery from thrombocytopenia in ITP patients and the lack of effect of aspirin on platelet 5HT content, provides initial evidence that human platelets accumulate 5HT during their life-span in circulation.     

Evidence that platelet buoyant density,but not size,correlates with platelet age in man

Following infusion of ⁵¹Cr-labeled autologous platelets into normal subjects, high-density (HD) and low-density (LD) platelet cohorts were isolated by prolonged centrifugation in isosmotic arabino-galactan (Stractan). Specific radioactivity of LD platelets declined rapidly post-infusion (T_1/2 = 1.5 days), but specific radioactivity of HD platelets remained constant or increased over a 3–4-day period and gradually declined for 6–7 days thereafter. These differences were exaggerated when platelet cohorts enriched in LD or HD cells by slow centrifugation in high-density albumin were labeled and transfused. Mean survival of a platelet cohort enriched with HD cells was significantly (P < 0.02) shorter (7.73 days) than that of a cohort enriched with LD cells (9.33 days). In normal subjects treated with aspirin, capacity for thromboxane synthesis was regained more rapidly (P < 0.05) in LD than in HD platelets. HD and LD platelets differed only slightly in mean volume (HD platelets = 7.57 μ³, LD platelets = 6.87 μ³, 0.05 < P < 0.01). We believe the most logical interpretation of these findings is that under normal conditions in man, newly formed platelets are less dense on the average than total platelets and become more dense as they age in the circulation. Thus, specific radioactivity of LD platelets declines rapidly as these platelets move into a more dense compartment and are replaced by newly formed, un-labelled cells; specific radioactivity of HD platelets remains constant or increases as labelled platelets enter this compartment in numbers equal to or greater than the number leaving it at the end of their life span. The similarity in mean volumes of LD and HD platelets suggests that platelet size is unrelated to platelet age under normal conditions.     

Kinetics of platelet density subpopulations in splenectomized mongrel dogs

Autologous ⁵¹Cr-platelet kinetic studies were performed in splenectomized mongrel dogs. Mean survival time of PRP-platelets was 5.4 ± 1.5 (SD) days (n = 6). The curves, though slightly curvilinear, showed mostly a linear type of decay, denoting that platelet removal from the circulation is mainly determined by aging of the cells. High-density (HD) and low-density (LD) platelet cohorts were isolated in Stractan gradients from samples drawn daily after infusion of labeled platelets. Specific radioactivity in HD cohorts declined rapidly postinfusion (T1/2 = 1.3 days), but specific radioactivity in LD platelets increased for 2 days and steadily declined for 4 days thereafter (n = 6). Labeled HD platelets, comprising 11.7% of the total population, lived significantly longer in circulation than LD platelets (19.1% of the total population) (n = 3). The patterns of decay of the radioactivity, however, do not have all the characteristics of pure age-cohort survival curves; 3.7 days after the infusion of labeled HD platelets, the specific radioactivity in LD cohorts was six times higher than on day 1, but attained only 20% of the initial specific radioactivity in HD platelets. After the infusion of labeled LD platelets no radioactivity was recovered in circulating HD cohorts. These findings indicate that mongrel dog platelets decrease in density with aging, but also that platelet density heterogeneity is in part determined during the thrombopoietic process. These data are consistent with those of other authors in rabbits and rhesus monkeys, but contrast with the observations that platelets in humans, baboons, and Macaca fasicularis monkeys increase in density with age, suggesting that the displacement of platelets toward compartments of either higher or lower density depends on the species under study.     

Intravascular and total body platelet equilibrium in healthy volunteers and in thrombocytopenic patients transfused with single donor platelets

Instrument platelet counts used in corrected count increment (CCI) and percent platelet recovery (PPR) formulas presume the transfused platelets are in equilibrium during the first hour after platelet transfusion. The timing of the pre-transfusion count affects CCI results, and we postulate that timing of CCI post transfusion affects CCI results. Platelet equilibrium using indium-111 platelet transfusions has not been reported. Platelet redistribution was studied in 16 healthy volunteers and 12 thrombocytopenic patients by generally infusing less than 72-hr stored single-donor platelets along with an aliquot of indium-111-labeled platelets by intravenous push. Counts were measured at 10, 15, 20, 60, and 120 min, and 24, 48, 72 hr along with continuous body scanning for 2 hr in healthy volunteers, and static organ scanning in patients and volunteers. Results indicated transfused platelets do not reach intravascular equilibrium for 60 min post-infusion and that the 10-min count cannot detect platelet refractoriness. However, total body equilibrium varies considerably between normal volunteers and thrombocytopenic patients. It is recommended to continue with the 1-hr post transfusion count. Am. J. Hematol. 58:165–176, 1998. © 1998 Wiley-Liss, Inc.     

In vitro quality of platelets during prolonged storage after washing with three platelet additive solutions

Background and Objectives Patients with anaphylactic transfusion reactions require washed platelet concentrates (PCs) for subsequent platelet (PLT) transfusions. New PLT additive solutions (PASs) contain substances that might be beneficial for the preservation of PLT function during storage. This study compares the quality of PLTs washed and stored with T‐Sol, Composol or SSP+. Study Design and Methods Fifteen buffy coats were pooled and divided into three parts. PCs with 30% plasma and 70% PAS (T‐Sol, Composol or SSP+) were prepared. Washing was performed on day 5 of storage. Ten PCs were prepared and washed with each PAS. In vitro variables including haemostatic function (clotting time and clot retraction) were analysed on day 5 before, directly after and up to 2 days after washing. Results Swirling was well preserved, and pH was within acceptable limits (6·4–7·4) during storage for all PASs. The PLT number was reduced by washing for all PASs, and T‐Sol PCs had a further decrease during storage. PLTs in T‐Sol were spontaneously more activated and had lower capacity to respond to an agonist than Composol or SSP+ PLTs. The haemostatic function was only slightly changed by washing and during postwashing storage. Conclusion PLTs washed with T‐Sol, Composol or SSP+ had good in vitro quality for two days after washing despite absence of glucose. PLTs in T‐Sol were more affected by the washing procedure and subsequent storage than Composol or SSP+ PLTs as judged by higher spontaneous activation.     

Platelet calmodulin correlates with platelet turnover

We measured the calmodulin content in platelets in 13 normal persons and in 62 patients with hematological diseases. The level of platelet calmodulin was higher in patients with idiopathic thrombocytopenic purpura (ITP), systemic lupus erythematosus, myeloproliferative disorders, acute leukemia in a recovery phase, aplastic anemia, thrombosis and hypersplenism as compared to the controls. Among the patients with ITP, calmodulin was lower in responders than in nonresponders and those at the initial diagnosis. We also measured the volume, life-span and aggregation of the platelets and demonstrated a significant relationship between the calmodulin level and the platelet volume, and a negative relationship between the calmodulin level and platelet life-span, there was no correlation between the calmodulin level and platelet aggregation. We thus conclude that platelet calmodulin is inversely correlated with platelet turnover.     

Preparation of Platelet Suspensions from Whole Blood in Buffer

A simple method for preparation of platelet suspensions from whole blood in buffer is described. The platelets and a fraction of the erythrocytes are processed simultaneously, whereby the erythrocytes serve as a supporting cushion in the centrifugation steps. Using this earlier described principle of platelet separation, platelet yields of 90–100% from whole blood could be achieved. Investigations of platelet aggregation and platelet morphology indicate that this method of separation is gentle. By obviating the selection of certain platelet populations this method may facilitate the interpretation of the results of in vitro and in vivo platelet-function studies.     

In vitro function of buffy coat-derived platelet concentrates stored for 9 days in CompoSol, PASII or 100% plasma in three different storage bags

BACKGROUND AND OBJECTIVES: The aim of the study was to compare the in vitro quality of buffy coat-derived platelet concentrates (PC) during extended storage in plasma or additive solution in three different storage bags. MATERIALS AND METHODS: A pooled and split design was chosen so that identical PCs were produced in either 100% plasma, 70% PASII : 30% plasma or 70% CompoSol : 30% plasma (n = 6 each). This was repeated for three different manufacturers' platelet storage bags (Fresenius, Baxter and Pall). PCs were sampled on days 1, 5, 7 and 9 of storage and tested in vitro using a variety of tests of platelet function. For each bag type, storage in PASII or Composol was compared with plasma (data taken across the entire storage period), and differences occurring with time were analysed for all storage media. RESULTS: The pH of all PCs was > 6.8 at day 9 of storage. In vitro platelet function, as assessed by markers of platelet activation and metabolism, of PCs stored in CompoSol appeared to be similar to that of PCs stored in plasma over 9 days of storage. In contrast, PCs stored in PASII tended to have significantly higher levels of platelet activation (almost a twofold increase in % platelets positive for CD62P by day 5) and lower hypotonic shock response (approximately 40%, by day 7) compared to either PCs stored in 100% plasma or 70% CompoSol. The magnitude of the differences observed between platelet storage media appeared to be dependent on the type of platelet storage bag with the highest degree of platelet activation and lowest hypotonic shock response values being observed in Fresenius bags in combination with PASII. CONCLUSIONS: The maintenance of platelet function in vitro during extended storage of PCs in platelet additive solutions is dependent on the combination of type of additive solution and type of platelet storage bag. For all bag types studied, storage in PASII resulted in poorer platelet function in vitro.     

The 'cherry buffy-coat syndrome', a cause of decreased platelet yield in platelet concentrates obtained from buffy-coats

BACKGROUND AND OBJECTIVES: A large number of European blood centres, including our own, use the buffy-coat method for platelet production. In this article we describe a previously unnoticed phenomenon shown by a proportion of buffy-coats, which display an unusually bright cherry colour and low platelet counts. MATERIALS AND METHODS: We performed bacterial cultures, platelet counts, pO2, pCO2 and pH, and evaluated platelet activation by flow cytometry in cherry versus normal-colour (control) buffy-coats. In addition, we compared donor characteristics in the two groups and platelet counts in the packed red blood cells (RBC) obtained from the original donations. Finally, we monitored the frequency of cherry buffy-coats in the bags of three manufacturers, and determined the concordance rate of two trained technicians in detecting cherry buffy-coats. RESULTS: Bacterial cultures were negative. Cherry buffy-coats contained significantly fewer platelets, more O2, less CO2 and had a significantly higher pH than normal buffy coats. Platelet activation was slightly higher in cherry buffy-coats. RBC from donations yielding cherry buffy-coats contained a significantly higher number of platelets than controls. Donor characteristics were not significantly different. Cherry buffy-coats were significantly more frequent with bags from one manufacturer (24%) than from others (9% and 11.6%). The concordance study showed excellent agreement. CONCLUSIONS: Our hypothesis is that the cherry colour is caused by O2 accumulation in buffy-coats with low platelet counts. The latter may be caused by platelet activation and aggregation during blood processing. Further work is needed to determine the cause of this phenomenon, its frequency in different laboratories and means to prevent it.