联合应用冰冻单采血小板与冷沉淀治疗弥散性血管内凝血

目的研究冰冻单采血小板与冷沉淀联合应用(冰冻联合组)治疗弥散性血管内凝血(DIC)的效果。方法将41例DIC患者随机分成两组：24例为冰冻联合组,17例为联合应用新鲜单采血小板和冷沉淀(新鲜联合组)。测定两组患者输前1 h和输后2 h指标：①凝血酶时间(TT)；②活化部分凝血活酶时间(APTT)；③凝血酶原时间(PT)；④纤维蛋白原(Fbg)；⑤血小板(PLT)；⑥统计比较两组输后24 h内续用悬浮红细胞量。结果冰冻联合组与新鲜联合组输后2 h比较：TT、PT、APTT及Fbg差异无统计学意义(P＞0．05),PLT显著减少(P＜0．05),24 h内人均续用红细胞量显著减少(P＜0．05)。结论冰冻单采血小板和冷沉淀联合应用治疗DIC具有更佳的止血疗效。     

Spontaneous bleeding in thrombocytopenia: Is it really spontaneous?

Spontaneous bleeding is a clinical hallmark of thrombocytopenia and can take multiple forms including petechiae, epistaxis, gum bleeding, or, in worst cases, intracranial hemorrhage. Those bleeding events are called “ spontaneous ” because they occur in the absence of overt trauma. Spontaneous bleeding manifestations have long been considered to be a direct consequence of low platelet counts. Nevertheless, although low platelet counts may lead to ultrastructural endothelial alterations, those alterations and the associated state of vascular fragility are unlikely sufficient to cause spontaneous rupture of the microvessel wall. Indeed, in addition to endothelial injury, factors capable of damaging the basement membrane are required to allow escape of red blood cells in the extravascular space. Therefore, despite their misleading name, spontaneous bleeding events in thrombocytopenia are most likely provoked and involve subclinical biological processes in which platelets normally intervene to ensure hemostasis. In this review, we discuss past and more recent studies on the possible triggers of spontaneous bleeding events in thrombocytopenia, with a particular focus on the role of inflammatory reactions.     

Interaction between the Staphylococcus aureus extracellular adherence protein Eap and its subdomains with platelets

S. aureus associated bacteremia can lead to severe infections with high risk of mortality (e.g. sepsis, infective endocarditis). Many virulence factors and adhesins of S. aureus are known to directly interact with platelets. Extracellular adherence protein, Eap, one of the most important virulence factors in S. aureus mediated infections is a multi-tandem domain protein and has been shown to interact with almost all cell types in the human circulatory system. By using amine reactive fluorescent N-hydroxysuccinimidyl (NHS)-ester dyes and by direct detection with primary fluorescently conjugated anti-histidine (His-tag) antibodies against detect N-terminal His6, we show Eap subdomain Eap D₃D₄ specifically interacts and rapidly activates human platelets. Furthermore, we validate our finding by using site directed directional immobilization of Eap D₃D₄ through N-terminal His₆ on nickel (II)-nitrilotriacetic acid (Ni-NTA) functionalized bacteriomimetic microbead arrays to visualize real-time platelet activation through calcium release assay. These methods offer an easily adoptable protocols for screening of S.aureus derived virulence factors and adhesins with platelets.     

Gender differences in platelet brain derived neurotrophic factor in patients with cardiovascular disease and depression

Women have a higher prevalence of depression compared to men. Serum levels of Brain-derived neurotrophic factor (BDNF) are decreased in depression. BDNF may also have a protective role in the pathogenesis of coronary artery disease (CAD) or events. We examined whether there are gender differences in BDNF levels in patients with stable CAD and comorbid depression. We enrolled 37 patients (17 women) with stable CAD with and without depression from a single medical center. All patients had depression assessment with the Beck Depression Inventory-II questionnaire. Both plasma and platelet BDNF were measured in all patients using a standard ELISA method. Platelet BDNF levels were higher than plasma BDNF levels in the entire group (5903.9 ± 1915.6 vs 848.5 ± 460.5 pg/ml, p < 0.001). Women had higher platelet BDNF levels than men (6954.2 ± 1685.6 vs. 5011.2 ± 1653.5 pg/ml, p < 0.001). Women without depression (BDI-II < 5, n = 8) had higher platelet BDNF than men without depression (n = 8, 7382.8 ± 1633.1 vs 4811.7 ± 1642.3 pg/ml, p = 0.007). Women with no or minimal depression (BDI < 14, n = 14) had higher platelet BDNF levels than men with no or minimal depression (n = 18, 6900.2 ± 1486.6 vs 4972.9 ± 1568.9 pg/ml, p = 0.001). The plasma BDNF levels were similar between men and women in all categories of depression. In conclusion, women with stable CAD have increased platelet BDNF levels when compared to men with stable CAD regardless of their level of depression. Sex specific differences in BDNF could possibly indicate differences in factors linking platelet activation and depression in men and women.     

Stimulation of lymphocytes by platelet-antibody-complexes and their role in the pathogenesis of idiopathic thrombocytopenia

Summary The effect of washed human platelets, platelet lysates, and platelet antibody complexes on¹⁴C-thymidine incorporation by human lymphocytes was studied. For sensitization of platelets, HLA-specific alloantibodies as well as platelet autoantibodies were used. Lymphocytes for in vitro cultures were collected from unsensitized individuals, healthy women with proven fetomaternal immunization against HLA antigens and patients with idiopathic thrombocytopenic purpura (ITP).Unsensitized platelets have a dose-dependent inhibitory effect on the in vitro proliferation of normal lymphocytes induced by mitogens (PHA, ConA, PWM). Platelet antibody complexes (allo- and autoantibodies; allogenic and autologous lymphocyte-platelet combinations) did not stimulate¹⁴C-thymidine incorporation. Lymphocytes from ITP patients showed a significantly reduced stimulatory response toward PHA compared to normal persons.These findings are discussed in the light of our present knowledge regarding the role of cellular immune reactions in the pathogenesis of ITP.These studies were supported by the Deutsche Forschungsgemeinschaft (Mu 277/8)     

Role of serotonin in development of esophageal and gastric fundal varices

AIM:To determine the effect of free serotonin concentrations in plasma on development of esophageal and gastric fundal varices. METHODS:This prospective study included 33 patients with liver cirrhosis and 24 healthy controls. Ultrasonography and measurement of serotonin concentration in plasma were carried out in both groups of subjects. The upper fiber panendoscopy was performed only in patients with liver cirrhosis. RESULTS:The mean plasma free serotonin levels were much higher in liver cirrhosis patients than in healthy controls (219.0 ± 24.2 nmol/L vs 65.4 ± 18.7 nmol/L,P < 0.0001). There was no significant correlation be-tween serotonin concentration in plasma and the size of the esophageal varices according to Spearman coefficient of correlation (rs =-0.217,P > 0.05). However,the correlation of plasma serotonin concentration and gastric fundal varices was highly significant (rs =-0.601,P < 0.01). CONCLUSION:Free serotonin is significant in pathogenesis of portal hypertension especially in development of fundal varices,indicating the clinical value of serotonergic receptor blockers in these patients.     

Biodegradable nanoparticles mimicking platelet binding as a targeted and controlled drug delivery system

This research aims to develop targeted nanoparticles as drug carriers to the injured arterial wall under fluid shear stress by mimicking the natural binding ability of platelets via interactions of glycoprotein Ib-alpha (GPIbα) of platelets with P-selectin of damaged endothelial cells (ECs) and/or with von Willebrand factor (vWF) of the subendothelium. Drug-loaded poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles were formulated using a standard emulsion method and conjugated with glycocalicin, the external fraction of platelet GPIbα, via carbodiimide chemistry. Surface-coated and cellular uptake studies in ECs showed that conjugation of PLGA nanoparticles, with GPIb, significantly increased nanoparticle adhesion to P-selectin- and vWF-coated surfaces as well as nanoparticle uptake by activated ECs under fluid shear stresses. In addition, effects of nanoparticle size and shear stress on adhesion efficiency were characterized through parallel flow chamber studies. The observed decrease in bound nanoparticle density with increased particle sizes and shear stresses is also explained through a computational model. Our results demonstrate that the GPIb-conjugated PLGA nanoparticles can be used as a targeted and controlled drug delivery system under flow conditions at the site of vascular injury.     

Elevated levels of platelet microparticles in carotid atherosclerosis and during the postprandial state

Background

Platelet microparticles (PMPs) possess proatherogenic and procoagulant properties which may play a role in atherogenesis and subsequent thromboembolic complications. The present study was conducted to investigate the possible relationship between carotid atherosclerosis and plasma concentrations of PMPs, and elucidate if plasma levels of PMPs were affected by postprandial hypertriglyceridemia.

Methods and results

Subjects with ultrasound-assessed carotid atherosclerotic plaques (echogenic; n = 20 and echolucent; n = 20), assessed by ultrasonography, and subjects without carotid plaques (n = 20) were recruited from a population-based study and underwent a standard fat tolerance test. Subjects with carotid plaques had significantly higher levels of large PMPs than subjects without carotid atherosclerotic plaques (96.7 ± 50.4 µg/l versus 56.1 ± 34.9 µg/l), after adjustments for traditional cardiovascular risk factors and use cardiovascular drugs (p = 0.021). Plasma PMPs were not associated with plaque echogenicity. Postprandial hypertriglyceridemia induced a similar increase in plasma PMPs within all groups. Significant correlations were found between an increase in plasma triglycerides and percent elevation in total PMPs (r = 0.29, p < 0.05) and large PMPs (r = 0.34, p < 0.01) in the postprandial phase.

Conclusions

Individuals with echogenic and echolucent carotid atherosclerotic plaques have statistically significant elevation of large plasma PMPs compared to age/sex-matched normal controls. Postprandial hypertriglyceridemia induces a significant, similar increase in plasma PMPs in individuals with and without carotid atherosclerotic plaques which could be of pathophysiological importance in atherogenesis.     

Higher mean platelet volume determined shortly after the symptom onset in acute ischemic stroke patients is associated with a larger infarct volume on CT brain scans and with worse clinical outcome

Objective

Mean platelet volume (MPV) determined shortly after the onset of acute ischemic stroke represents the pre-stroke values. Data on its relationship to stroke severity/outcome have been conflicting. We related MPV to infarct volume on CT brain scans and risk of death/dependence 7 days and 3 months post-stroke.

Methods

MPV (within 30 h since stroke onset), infarct volume (13–83 h since stroke onset) and clinical outcomes were evaluated in 81 consecutive patients (32 men, age 52–91 years, 10 small artery occlusion, 10 large artery atherosclerosis, 29 cardioembolic, 32 multiple probable/possible etiology).

Results

Higher MPV was independently associated with larger ln-infarct volume [estimate 0.259, 95% confidence interval (CI) 0.004–0.513, P = 0.046], greater risk of death/dependence 7 days post-stroke [relative risk (RR) = 1.077, 95% CI 1.005–1.115, P = 0.036], and greater risk of death/dependence 3 months post-stroke (RR = 1.077, 95% CI 1.001–1.158, P = 0.048). Considered covariates: stroke etiology, CT scan timing, platelet count and other hematological parameters, demographic variables, history of cerebrovascular, cardiac or cardiovascular diseases, diabetes, serum chemistry, previous antiplatelet and statin use and treatments delivered after the index event.

Conclusions

Data support the view about MPV as a determinant of severity/outcome of the acute ischemic stroke.     

Delayed thrombin-induced platelet-fibrin clot generation by clopidogrel: a new dose-related effect demonstrated by thrombelastography in patients undergoing coronary artery stenting

BACKGROUND: We have previously demonstrated that clopidogrel reduces platelet activation and aggregation in patients undergoing stenting. However, the effect of the clopidogrel loading dose on the rate of thrombin-induced platelet-fibrin clot formation is unknown in this patient population. METHODS AND RESULTS: Using thrombelastography (TEG) we measured the time to platelet-fibrin clot formation (R), a marker of the speed of thrombin generation, in 120 patients undergoing elective coronary artery stenting treated with standard and high loading doses of clopidogrel. Platelet reactivity to adenosine diphosphate (ADP) by light transmittance aggregometry (LTA) was determined simultaneously. Measurements were made immediately before and at 24 h after clopidogrel treatment. Clopidogrel produced a prolongation in R (4.4+/-1.4 min pre vs. 5.4+/-1.7 min post, p<0.001) that directly correlated with the change in platelet aggregation (r=0.65, p<0.0001). Prolongation in R was greatest in patients treated with a high loading dose (p=0.004). CONCLUSIONS: Delayed thrombin-induced platelet-fibrin clot formation as measured by TEG is a newly reported dose-related effect of clopidogrel that may contribute to the overall antithrombotic properties of the drug in patients undergoing stenting. This effect was more marked in patients loaded with 600 mg, lending further mechanistic support for this dose of clopidogrel as a more effective antithrombotic regimen than the standard 300 mg dose. Measurement of R may serve as a new indicator of clopidogrel responsiveness.