Thrombosis and Haemostasis
0340-6245
2567-689X
Đức
Cơ quản chủ quản: Georg Thieme Verlag , GEORG THIEME VERLAG KG
Lĩnh vực:
Hematology
Phân tích ảnh hưởng
Thông tin về tạp chí
Thrombosis and Haemostasis publishes reports on basic, translational and clinical research dedicated to novel results and highest quality in any area of thrombosis and haemostasis, vascular biology and medicine, inflammation and infection, platelet and leukocyte biology, from genetic, molecular & cellular studies, diagnostic, therapeutic & preventative studies to high-level translational and clinical research. The journal provides position and guideline papers, state-of-the-art papers, expert analysis and commentaries, and dedicated theme issues covering recent developments and key topics in the field.
Các bài báo tiêu biểu
Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets Summary Acidosis is one of the hallmarks of tissue injury such as trauma, infection, inflammation, and tumour growth. Although platelets participate in the pathophysiology of all these processes, the impact of acidosis on platelet biology has not been studied outside of the quality control of laboratory aggregation assays or platelet transfusion optimization. Herein, we evaluate the effect of physiologically relevant changes in extracellular acidosis on the biological function of platelets, placing particular emphasis on haemostatic and secretory functions. Platelet haemostatic responses such as adhesion, spreading, activation of αIIbβ3 integrin, ATP release, aggregation, thromboxane B2 generation, clot retraction and procoagulant activity including phosphatidilserine exposure and microparticle formation, showed a statistically significant inhibition of thrombin-induced changes at pH of 7.0 and 6.5 compared to the physiological pH (7.4). The release of alpha granule content was differentially regulated by acidosis. At low pH, thrombin or collagen-induced secretion of vascular endothelial growth factor and endostatin were dramatically reduced. The release of von Willebrand factor and stromal derived factor-1α followed a similar, albeit less dramatic pattern. In contrast, the induction of CD40L was not changed by low pH, and P-selectin exposure was significantly increased. While the generation of mixed platelet-leukocyte aggregates and the increased chemotaxis of neutrophils mediated by platelets were further augmented under acidic conditions in a P-selectin dependent manner, the increased neutrophil survival was independent of P-selectin expression. In conclusion, our results indicate that extracellular acidosis downregulates most of the haemostatic platelet functions, and promotes those involved in amplifying the neutrophil-mediated inflammatory response.
Tập 107 Số 01 - Trang 99-110 - 2012
Aspirin and P2Y12 Inhibitors in platelet-mediated activation of neutrophils and monocytes Summary Platelets are key players in haemostasis and represent a pivotal link between inflammation, immunity and atherogenesis. Depending on the (patho)physiological environment platelets modulate various leukocyte functions via release of inflammatory mediators and direct cell-cell interactions. Elevated levels of circulating platelet-leukocyte aggregates are found in patients suffering from several thrombotic or inflammatory conditions. Platelet-monocyte and platelet-neutrophil interaction can trigger pro- and anti-inflammatory responses and modulate effector functions of all leukocyte subpopulations. These platelet-mediated immune responses have implications for the progression of cardiovascular diseases and also play a crucial role during infections, cancer, transplantations and other inflammatory diseases of several organs. Antiplatelet therapy including the COX inhibitor aspirin and/or ADP receptor P2Y12 inhibitors such as clopidogrel, prasugrel and ticagrelor are the therapy of choice for various cardiovascular complications. Both aspirin and P2Y12 inhibitors attenuate platelet-leukocyte interactions, thereby also modulating immune responses. This may have beneficial effects in some pathological conditions, while it might be detrimental in others. This review aims to summarise the current knowledge on platelet-leukocyte interactions and the impact of aspirin and P2Y12 inhibition on platelet-mediated immune responses and to give an overview on the effects of antiplatelet therapy on platelet-leukocyte interplay in various diseases.
Tập 114 Số 09 - Trang 478-789 - 2015
Intracellular alkalinization augments capacitative Ca2+ entry in platelets Summary In order to elucidate the significance of intracellular alkalinization in signal transduction of platelets, we investigated the effects on capacitative Ca2+ entry (CCE) of intracellular alkalinization that was induced by NH4Cl. Addition of NH4Cl (10 mM) to the medium resulted in an elevation of intracellular pH by about 0.35, which was eliminated by simultaneous addition of propionate (20 mM), an inducer of intracellular acidification, to the medium. CCE was induced by an extracellular addition of Ca2+ to platelets in which Ca2+ stores had been depleted by stimulation with thapsigargin in nominally Ca2+-free medium. NH4Cl markedly augmented CCE and subsequent platelet aggregation, both of which were abolished in the presence of SKF-96365, an inhibitor of capacitative Ca2+ entry in non-excitable cells such as platelets. The augmentation of CCE and subsequent aggregation by NH4Cl was not observed in the presence of propionate or SKF-96365. Extracellular alkalosis induced by Tris also markedly augmented CCE and subsequent aggregation. These augmenting effects of extracellular alkalosis by Tris were significantly but incompletely inhibited by simultaneous addition of propionate (20 mM), which completely eliminated elevation of intracellular pH elicited by Tris. Thus, the augmenting effect of extracellular alkalosis on CCE was in part mediated by intracellular alkalosis. These findings suggest that intracellular alkalinization is a potent signal that augments CCE in platelets.
Tập 90 Số 12 - Trang 1121-1127 - 2003
Enhanced platelet aggregation and activation under conditions of hypothermia Summary The effects on platelet function of temperatures attained during hypothermia used in cardiac surgery are controversial. Here we have performed studies on platelet aggregation in whole blood and platelet-rich plasma after stimulation with a range of concentrations of ADP, TRAP, U46619 and PAF at both 28°C and 37°C. Spontaneous aggregation was also measured after addition of saline alone. In citrated blood, spontaneous aggregation was markedly enhanced at 28°C compared with 37°C. Aggregation induced by ADP was also enhanced. Similar results were obtained in hirudinised blood. There was no spontaneous aggregation in PRP but ADP-induced aggregation was enhanced at 28°C. The P2Y12 antagonist AR-C69931 inhibited all spontaneous aggregation at 28°C and reduced all ADP-induced aggregation responses to small, reversible responses. Aspirin had no effect. Aggregation was also enhanced at 28°C compared with 37°C with low but not high concentrations of TRAP and U46619. PAF-induced aggregation was maximal at all concentrations when measured at 28°C, but reversal of aggregation was seen at 37°C. Baseline levels of platelet CD62P and CD63 were significantly enhanced at 28°C compared with 37°C. Expression was significantly increased at 28°C after stimulation with ADP, PAF and TRAP but not after stimulation with U46619. Overall, our results demonstrate an enhancement of platelet function at 28°C compared with 37°C, particularly in the presence of ADP.
Tập 98 Số 12 - Trang 1266-1275 - 2007
Reversible Inhibition of Human Platelet Activation by Hypothermia In Vivo and In Vitro Summary A hypothermia-induced hemorrhagic diathesis is associated with cardiopulmonary bypass, major surgery, and multiple trauma, but its pathophysiological basis is not well understood. We examined the hypothesis that hypothermia reversibly inhibits human platelet activation in vitro and in vivo. Platelet activation was studied in normal volunteers by whole blood flow cytometric analysis of modulation of platelet surface GMP-140 and the glycoprotein (GP) Ib-IX complex in: a) shed blood emerging from a standardized in vivo bleeding time wound; b) peripheral blood activated in vitro with either thrombin (in the presence of gly-pro-arg-pro, an inhibitor of fibrin polymerization) or the stable thromboxane (TX) A2 analogue U46619. Platelets in peripheral whole blood were activated at temperatures between 22° C and 37° C. the forearm skin temperature was maintained at temperatures between 22° C and 37° C prior to and during the bleeding time incision. Platelet aggregation was studied in shed blood by flow cytometry and in peripheral blood by aggregometry. Generation of TXB 2 (the stable metabolite of TXA 2) was determined by radioimmunoassay. In vitro, hypothermia inhibited both thrombin- and U46619-induced upregulation of GMP-140, downregulation of the GPIb-IX complex, platelet aggregation, and TXB2 generation. These inhibitory effects of hypothermia were all completely reversed by rewarming the blood to 37° C. In vivo, platelet activation was inhibited by hypothermia as shown by 5 independent assays of shed blood: upregulation of GMP-140, downregulation of the GPIb-IX complex, platelet aggregate formation, TXB 2
ggeneration, and the bleeding time. In summary, by a combination of immunologic, biochemical, and functional assays, we demonstrate that hypothermia inhibits human platelet activation in whole blood in vitro and in vivo. Rewarming hypothermic blood completely reverses the activation defect. These results suggest that maintaining normothermia or rewarming a hypothermic bleeding patient may reduce the need for platelet transfusions.
Tập 71 Số 05 - Trang 633-640 - 1994
Critical temperature ranges of hypothermia-induced platelet activation: Possible implications for cooling patients in cardiac surgery Summary Cooling of the patient is routinely applied in cardiac surgery to protect organs against ischemia. Hypothermia induces activation of platelets, but the effects of temperatures such as used during cardiac surgery are not well described. To investigate this in an in-vitro study heparinized whole blood was incubated at different temperatures (37°C, 34.5°C, 32°C, 29.5°C, 27°C, 24.5°C, 22°C, 19.5°C and 17°C).The effect of these temperatures on aggregation, P-selectin expression, GP IIb/IIIa activation and platelet microparticle (PMP) formation of unstimulated and ADP-stimulated platelets of 36 subjects was evaluated in flow cytometry. A four-parametric logistic model was fitted to depict the temperature effect on platelet parameters. Lower temperatures increased aggregates, P-selectin expression, and GP IIb/IIIa activation. The number of PMPs decreases with hypothermia. Additional experiments revealed a slight influence of heparin on platelet P-selectin expression but excluded an effect of this anticoagulant on the other evaluated parameters. Threshold temperatures, which mark 5% changes of platelet parameters compared to values at 37°C, were calculated. On ADP-stimulated platelets the thresholds for P-selectin expression and GP IIb/IIIa activation are 34.0°C and 36.4°C, respectively, and lie in the temperature range routinely applied in cardiac surgery. Hypothermia- induced platelet activation may develop in most patients undergoing cardiac surgery, possibly resulting in thromboembolic events, coagulation defects, and proinflammatory leukocyte bridging by P-selectin bearing platelets and PMPs. These findings suggest that pharmacological protection of platelets against hypothermia-induced damage may be beneficial during cardiac surgery.
Tập 97 Số 04 - Trang 608-616 - 2007
The Treatment of Bleeding in Acquired Haemophilia with Recombinant Factor VIIa: A Multicentre Study Summary Recombinant factor Vila was used to treat 38 patients with acquired haemophilia participating in the Novoseven compassionate-use program. 19 were male, median age 59, range 2-89 years. The median pre-treatment anti-human (H) and anti-porcine (P) inhibitor titre was H 43 BU/ml (range 1-4500) and P 4.5 BU/ml (range 0-1600). Recombinant factor VIIa was used as first-line therapy for 14 bleeding episodes and as salvage-therapy for 60 episodes which failed to respond to blood-product therapy given for a median of four days (range 1-21 days) prior to treatment with rVIIa. Pre-rVIIa treatment was not reported for four episodes. The indications for treatment were 7 haemarthroses, 40 muscle haematomas, 20 urinary or GI haemorrhages and 3 surgical interventions. The median starting dose of rVIIa was 90.4 ug/kg (range 45-181). A median of 28 doses (range 1-541) were given per episode, over a median 3.9 days (range 0-43). Efficacy was assessed clinically 8 and 24 h after the start of rVIIa and at the end of treatment. A good response was obtained in all 14 bleeds for which rVIIa was used as first-line therapy. The response after 24 h of rVIIa salvage-therapy for 60 bleeds was good in 75%, partial in 17% and poor in 8%. Efficacy was unreported in 4 cases. The median prothrombin time (PTT) shortened from 12 s (range 9.3-20) pre-treatment to 8.8 s (range 6-14) during treatment. The clinical response did not correlate with the dose of rVIIa used, the type of bleed or the degree of shortening of the PTT following rVIIa infusion. Three patients died from haemorrhagic complications of acquired haemophilia. This mortality of 7.9% is lower than previously reported for this condition. Although one patient developed DIC during treatment with rVIIa, this was probably attributable to hypovolaemic shock, massive transfusion and the use of PCCs. This study demonstrates that rVIIa is a safe, useful and effective treatment for bleeding in patients with acquired haemophilia.
Tập 78 Số 06 - Trang 1463-1467 - 1997
A Prospective, Randomized Trial of Prednisone and Cyclophosphamide in the Treatment of Patients with Factor VIII Autoantibodies Summary Thirty-one non-hemophilic patients with acquired antibodies to factor VIII were entered into a prospective, randomized, multi- institutional trial to determine the safety and efficacy of prednisone (P), cyclophosphamide ©, or the combination in the treatment of this disorder. Patients were eligible if they had antibody demonstrated by the Bethesda assay, had not received these agents previously, and gave informed consent. All patients were treated initially with P, 1 mg/kg, for 3 weeks. If the antibody persisted and there was no rise in factor VIII activity, patients were randomized to either continue P for an additional 6 weeks; taper P and begin C, 2 mg per kg; or continue P and add C. Antibody disappeared in 10 during the initial P therapy, and in three of four others randomized to continue on P; one patient was discontinued because of an herpetic infection. Antibody disappeared in three of six patients treated with C alone, and five of ten given C and P. The titer of antibody was significantly lower in responders than in non-responders (p = 0.003), but seven patients with titers of more than five Bethesda units had complete remissions. There was no difference in antibody titers between those responding to P and those responding to C. We conclude that all patients with acquired antibodies to factor VIII should receive initial management with P, and that C is effective as second-line therapy for many of those who are steroid-resistant.
Tập 70 Số 05 - Trang 753-757 - 1993
A Survey of 215 Non-Hemophilic Patients with Inhibitors to Factor VIII Summary Information was obtained by questionnaire about 215 nonhemophilic patients who developed inhibitors against factor VIII (antihemophilic factor). The majority of the patients were over 50 years of age, and approximately equal numbers of males and females were reported. Rheumatoid arthritis was present in 8% of the cases, 7% occurred during pregnancy or the post-partum period, and in several there was an association with allergy to penicillin, asthma, “auto-immune” diseases, or malignancy. In 46% of cases, no underlying disorders were identified. Major bleeding was observed in 87 % of patients, and in 22%, death was attributed either directly or indirectly to the presence of the inhibitor. In 11 of 31 patients receiving no therapy other than supportive transfusions of blood or factor VIII concentrate, the inhibitor disappeared after being present for an average duration of 14 months. Corticosteriods were thought to be effective in abolishing the inhibitor in 22 of 45 patients in whom these were the only drugs administered. Twenty-eight patients received azathioprine as well as corticosteriods; in 19, the inhibitor declined or disappeared during treatment. Finally, 80 patients were treated with cyclophosphamide; in 37 there was a favorable outcome. Inhibitors in children and post-partum patients were more likely to disappear spontaneously or with steroid therapy, whereas those in patients with rheumatoid arthritis or other “autoimmune” disorders required treatment with alkylating agents. However, before any specific therapy can be recommended for this disorder, prospective trials of potential therapeutic agents should be conducted in selected subgroups.
Tập 45 Số 03 - Trang 200-203 - 1981
Bone morphogenetic protein 4 regulates microRNAs miR-494 and miR-126–5p in control of endothelial cell function in angiogenesis Summary MicroRNAs are small non-coding RNAs that negatively regulate posttranscriptional gene expression. Several microRNAs have been described to regulate the process of angiogenesis. Previously, we have shown that bone morphogenetic protein 4 (BMP4) increased the proangiogenic activity of endothelial cells. In this project, we now investigated how the pro-angiogenic BMP4 effect is mediated by microRNAs. First, we performed a microRNA array with BMP4-stimulated human umbilical vein endothelial cells (HUVECs). Among the topregulated microRNAs, we detected a decreased expression of miR-494 and increased expression of miR-126–5p. Next, we analysed the canonical Smad and alternative signalling pathways, through which BMP4 would regulate miR-126–5p and miR-494 expression. Furthermore, the functional effect of miR-494 and miR-126–5p on endothelial cells was investigated. MicroRNA-494 overexpression decreased endothelial cell proliferation, migration and sprout formation. Consistently, miR-494 inhibition increased endothelial cell function. As potential miR-494 targets, bFGF and BMP endothelial cell precursorderived regulator (BMPER) were identified and confirmed by western blot. Luciferase assays showed direct miR-494 binding in BMPER 3’UTR. In contrast, miR-126–5p overexpression increased pro-angiogenic endothelial cell behaviour and, accordingly, miR-126–5p inhibition decreased endothelial cell function. As a direct miR-126–5p target we identified the anti-angiogenic thrombospondin-1 which was confirmed by western blot analysis and luciferase assays. In the Matrigel plug assay application of antagomiR-494 increased endothelial cell ingrowth, whereas antagomiR-126–5p treatment decreased cell ingrowth in vivo. Taken together, through differential regulation of the anti-angiomiR-494 and the angiomiR-126–5p by BMP4 both microRNAs contribute to the pro-angiogenic BMP4 effect on endothelial cells. Supplementary Material to this article is available online at www.thrombosis-online.com.
Tập 117 Số 04 - Trang 734-749 - 2017