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Sample records for blood platelet function

  1. Thrombocytopenia model with minimal manipulation of blood cells allowing whole blood assessment of platelet function.

    PubMed

    Tiedemann Skipper, Mette; Rubak, Peter; Halfdan Larsen, Ole; Hvas, Anne-Mette

    2016-06-01

    In vitro models of thrombocytopenia are useful research tools. Previously published models have shortcomings altering properties of platelets and other blood components. The aim of the present study was to develop a whole blood method to induce thrombocytopenia with minimal manipulation, and to describe platelet function in induced thrombocytopenia in individuals with healthy platelets. Hirudin anticoagulated blood was obtained from 20 healthy volunteers. One part of the blood was gently centrifuged at 130g for 15 minutes. The platelet-rich plasma was replaced with phosphate-buffered saline to establish thrombocytopenia. Various levels of thrombocytopenia were achieved by combining different volumes of baseline whole blood and thrombocytopenic blood. Platelet counts were measured by flow cytometry (Navios, Beckman Coulter) and routine haematological analyser (Sysmex XE-5000). Platelet function was analysed by impedance aggregometry (Multiplate® Analyzer, Roche) and by flow cytometry (Navios, Beckman Coulter) using collagen, adenosine diphosphate, thrombin receptor activating peptide-6 and ristocetin as agonists. Median baseline platelet count was 227×10(9)/l. The in vitro model yielded median platelet counts at 51×10(9)/l (range 26-93×10(9)/l). We observed minor, yet significant, changes in platelet size and maturity from baseline to modelled thrombocytopenia. In the thrombocytopenic samples, significant and positive linear associations were found between platelet count and platelet aggregation across all agonists (all p-values<0.001). Platelet function assessed by flow cytometry showed minimal alterations in the thrombocytopenic samples. A new whole blood-based model of thrombocytopenia was established and validated. This new model serves as a useful future tool, particularly to explore platelet function in patients with thrombocytopenia. PMID:26555800

  2. Functional assay of antiplatelet drugs based on margination of platelets in flowing blood.

    PubMed

    Eichinger, Colin D; Fogelson, Aaron L; Hlady, Vladimir

    2016-06-01

    A novel functional assay of antiplatelet drug efficacy was designed by utilizing the phenomena of platelet margination in flowing blood and transient platelet contacts with surface-immobilized platelet agonists. Flow margination enhances transient contacts of platelets with the walls of flow chambers covered with surface-immobilized proteins. Depending on the type and the surface density of the immobilized agonists, such transient interactions could "prime" the marginated platelet subpopulation for enhanced activation and adhesion downstream. By creating an upstream surface patch with an immobilized platelet agonist, platelet flow margination was used to test how effective antiplatelet drugs are in suppressing downstream platelet activation and adhesion. The platelet adhesion downstream was measured by a so-called "capture" patch region close to the distal end of the flow chamber. Platelet adhesion downstream was found to be dose-dependent on the upstream surface coverage of the "priming" patch, with immobilized fibrinogen acting as a platelet agonist. Several antiplatelet agents (acetylsalicylic acid, eptifibatide, and tirofiban) were evaluated for their efficacy in attenuating downstream adhesion after upstream platelet priming. The activation of the platelet population was found to be dependent on both the extent of the upstream agonist stimulus and the antiplatelet drug concentration. Such a relationship provides an opportunity to measure the efficacy of specific antiplatelet agents against the type and concentration of upstream platelet agonists. PMID:27030476

  3. Variability in platelet responses to collagen--comparison between whole blood perfusions, traditional platelet function tests and PFA-100.

    PubMed

    Lepäntalo, A; Beer, J H; Siljander, P; Syrjälä, M; Lassila, R

    2001-07-15

    The purpose of this study was to determine if the results obtained in platelet function tests and whole blood perfusions are associated with those in platelet function analyser (PFA)-100. We used collagen type I monomers and fibrils to analyse the distinct roles of glycoprotein (GP) Ia/IIa and other collagen receptors in flowing blood under a high shear rate (1600/s) and in aggregation studies. Also, anticoagulation [citrate vs. D-phenylalanyl-1-prolyl-1 arginine chloromethyl ketone (PPACK)] was varied to enhance the functions of GP Ia/IIa, since it has been shown that the cation-poor environment of citrated blood impairs GP Ia/IIa-dependent platelet recruitment. Large interindividual variability (45-fold) was detected in deposition of platelets in whole blood perfusions over collagen monomers, whereas this variation was only fourfold in fibrils. In PFA, this variation was reduced to 2.5-fold. However, platelet deposition on monomers is associated with epinephrine-enhanced PFA (r=-.49, P<.03), whereas platelet deposition on fibrils is correlated with adenosine diphosphate (ADP)-enhanced PFA (r=-.47, P<.05), suggesting a distinct synergism between epinephrine and monomers (GP Ia/IIa) as well as ADP with fibrils (other collagen receptors). Donors with 807 C/C polymorphism of GP Ia (n=14) had longer lag phase in aggregation experiments compared with C/T (n=7) both by monomers and fibrils (P<.04), but these polymorphisms with their mild impact on GP Ia/IIa activity did not markedly differ in other tests. In conclusion, the results obtained in perfusion studies and PFA experiments correlated, but PFA fails to reveal the large-scale variability related to collagen-induced platelet responses. PMID:11457470

  4. Blood rheology and platelet function in untreated early-stage essential hypertensives complicated with metabolic syndrome.

    PubMed

    Sugimori, Hiroko; Tomoda, Fumihiro; Koike, Tsutomu; Kinuno, Hiroyuki; Kurosaki, Hiroko; Masutani, Toshitaka; Inoue, Hiroshi

    2012-01-01

    We examined whether hemorheology and platelet function are affected in essential hypertensives (EHTs) of the World Health Organization stage I when complicated with metabolic syndrome (Mets). In 156 untreated EHTs, blood viscosity and platelet surface markers were determined. Blood viscosity was significantly elevated in 54 subjects with Mets compared with 102 subjects without Mets. Hematocrit and plasma viscosity increased in the group with Mets, although red blood cell rigidity index "k" did not differ between groups. As a whole group, blood viscosity correlated positively with hematocrit and plasma viscosity. Additionally, plasma viscosity correlated positively with plasma leptin, triglyceride, homeostasis model assessment index, C-reactive protein, and plasma fibrinogen, but negatively with high-density lipoprotein cholesterol. In contrast, no differences were seen in platelet surface markers between groups. In conclusion, EHTs of the early stage complicated with Mets are characterized by increased blood viscosity due to hemoconcentration and increased plasma viscosity. PMID:22570768

  5. Examination of platelet function in whole blood under dynamic flow conditions with the cone and plate(let) analyzer: effect of erythrocytosis and thrombocytosis.

    PubMed

    Peerschke, Ellinor I; Silver, Richard T; Weksler, Babette B; Yin, Wei; Bernhardt, Bernard; Varon, David

    2007-03-01

    We studied cone and plate(let) analysis (CPA) for evaluating global platelet function in whole blood under arterial flow conditions (approximately 1,800 seconds(-1)). CPA allows direct visualization and quantitation of platelet adhesion (surface coverage [SC]) and determination of average aggregate size (AS) following brief shearing of a small blood sample (3.2% sodium citrate) in plastic wells. By using blood from healthy volunteers manipulated to alter platelet or RBC counts and blood from patients with myeloproliferative disorders (MPDs), quantitative and qualitative changes in SC and AS were observed. Thrombocytosis resulted in increased SC, whereas erythrocytosis increased AS. The RBC volume (mean corpuscular volume) had no effect. It is interesting that differences in CPA AS were discerned among subgroups of patients with MPD undergoing different treatment regimens. These studies suggest that CPA platelet deposition patterns may provide novel insight into global platelet function during hemodynamic flow. PMID:17276938

  6. Effects of the new glycopeptide antibiotic teicoplanin on platelet function and blood coagulation.

    PubMed Central

    Agnelli, G; Longetti, M; Guerciolini, R; Menichetti, F; Grasselli, S; Boldrini, F; Bucaneve, G; Nenci, G G; Del Favero, A

    1987-01-01

    Teicoplanin, a new glycopeptide antibiotic, is structurally related to ristocetin, an antibiotic known to induce human platelet agglutination and, thus, thrombocytopenia and thromboembolic side effects. The aim of this study was to evaluate the effects of teicoplanin on platelet function in vitro and ex vivo and on blood coagulation ex vivo. In the in vitro studies, spontaneous platelet aggregation; platelet aggregation induced by ADP, collagen, and ristocetin; and the release of beta-thromboglobulin from platelets were assessed. Platelets from healthy subjects were incubated with teicoplanin at final concentrations of 100, 1,500, 5,000, and 10,000 micrograms/ml. The maximal achievable concentration with therapeutic doses is 100 micrograms/ml. When compared with saline, teicoplanin at concentrations of 100 and 1,500 micrograms/ml had no effect on platelet function, but at concentrations of 5,000 and 10,000 micrograms/ml, it induced greater spontaneous platelet aggregation (P less than 0.01) and inhibited platelet aggregation induced by ADP, collagen, and ristocetin (P less than 0.01). Teicoplanin at concentrations of 100, 1,500, and 5,000 micrograms/ml did not induce the release of beta-thromboglobulin, in contrast to teicoplanin at a concentration of 10,000 micrograms/ml and ristocetin at a concentration of 1.5 mg/ml (P less than 0.01). In the ex vivo studies, platelet count, bleeding time, plasma beta-thromboglobulin, platelet aggregation induced by ADP, ristocetin, and epinephrine, activated partial thromboplastin time, prothrombin time, thrombin clotting time, and serum fibrinogen degradation products were evaluated at days 0, 3, and 6 and at 72 h after the end of therapy. All subjects completed the study without evidence of side effects. When compared with the pretreatment values, none of the values from these assays showed a significant change at any time during and after treatment. We concluded that platelet function and blood coagulation are not affected by

  7. Diminished adhesion and activation of platelets and neutrophils with CD47 functionalized blood contacting surfaces.

    PubMed

    Finley, Matthew J; Rauova, Lubica; Alferiev, Ivan S; Weisel, John W; Levy, Robert J; Stachelek, Stanley J

    2012-08-01

    CD47 is a ubiquitously expressed transmembrane protein that, through signaling mechanisms mediated by signal regulatory protein alpha (SIRPα1), functions as a biological marker of 'self-recognition'. We showed previously that inflammatory cell attachment to polymeric surfaces is inhibited by the attachment of biotinylated recombinant CD47 (CD47B). We test herein the hypothesis that CD47 modified blood conduits can reduce platelet and neutrophil activation under clinically relevant conditions. We appended a poly-lysine tag to the C-terminus of recombinant CD47 (CD47L) allowing for covalent linkage to the polymer. SIRPα1 expression was confirmed in isolated platelets. We then compared biocompatibility between CD47B and CD47L functionalized polyvinyl chloride (PVC) surfaces and unmodified control PVC surfaces. Quantitative and Qualitative analysis of blood cell attachment to CD47B and CD47L surfaces, via scanning electron microscopy, showed strikingly fewer platelets attached to CD47 modified surfaces compared to control. Flow cytometry analysis showed that activation markers for neutrophils (CD62L) and platelets (CD62P) exposed to CD47 modified PVC were equivalent to freshly acquired control blood, while significantly elevated in the unmodified PVC tubing. In addition, ethylene oxide gas sterilization did not inhibit the efficacy of the CD47 modification. In conclusion, CD47 modified PVC inhibits both the adhesion and activation of platelets and neutrophils. PMID:22613135

  8. Evaluation of store lesion in platelet obtained by apheresis compared to platelet derived from whole blood and its impact on the in vitro functionality.

    PubMed

    Quintero, M; Núñez, M; Mellado, S; Maldonado, M; Wehinger, S

    2015-12-01

    Platelet units for transfusion purposes are obtained manually from whole blood or by apheresis, in an automated process. In both methods, platelets during storage present a characteristics grouped under the name "storage lesion" that are associated with adverse effects on platelet units. Oxidative stress has been claimed to be one of major causes, leading to activation and apoptosis processes affecting their post transfusion functionality. In this work, we observed an association between apheresis and a reduced presence of oxidative stress and better results in functional markers in stored platelets, compared to manually obtained platelets. Then, apheresis which would ensure a greater number of functional platelets during the 5 days of storage, compared to concentrates obtained from whole blood. PMID:26043812

  9. Platelet function and ageing.

    PubMed

    Jones, Chris I

    2016-08-01

    There are clear age-related changes in platelet count and function, driven by changes in hematopoietic tissue, the composition of the blood and vascular health. Platelet count remains relatively stable during middle age (25-60 years old) but falls in older people. The effect of age on platelet function is slightly less clear. The longstanding view is that platelet reactivity increases with age in an almost linear fashion. There are, however, serious limitations to the data supporting this dogma. We can conclude that platelet function increases during middle age, but little evidence exists on the changes in platelet responsiveness in old age (>75 years old). This change in platelet function is driven by differential mRNA and microRNA expression, an increase in oxidative stress and changes in platelet receptors. These age-related changes in platelets are particularly pertinent given that thrombotic disease and use of anti-platelet drugs is much more prevalent in the elderly population, yet the majority of platelet research is carried out in young to middle-aged (20-50 years old) human volunteers and young mice (2-6 months old). We know relatively little about exactly how platelets from people over 75 years old differ from those of middle-aged subjects, and we know even less about the mechanisms that drive these changes. Addressing these gaps in our knowledge will provide substantial understanding in how cell signalling changes during ageing and will enable the development of more precise anti-platelet therapies. PMID:27068925

  10. Functional Comparison of Induced Pluripotent Stem Cell- and Blood-Derived GPIIbIIIa Deficient Platelets

    PubMed Central

    Haas, Jessica; Sandrock-Lang, Kirstin; Gärtner, Florian; Jung, Christian Billy; Zieger, Barbara; Parrotta, Elvira; Kurnik, Karin; Sinnecker, Daniel; Wanner, Gerhard; Laugwitz, Karl-Ludwig; Massberg, Steffen; Moretti, Alessandra

    2015-01-01

    Human induced pluripotent stem cells (hiPSCs) represent a versatile tool to model genetic diseases and are a potential source for cell transfusion therapies. However, it remains elusive to which extent patient-specific hiPSC-derived cells functionally resemble their native counterparts. Here, we generated a hiPSC model of the primary platelet disease Glanzmann thrombasthenia (GT), characterized by dysfunction of the integrin receptor GPIIbIIIa, and compared side-by-side healthy and diseased hiPSC-derived platelets with peripheral blood platelets. Both GT-hiPSC-derived platelets and their peripheral blood equivalents showed absence of membrane expression of GPIIbIIIa, a reduction of PAC-1 binding, surface spreading and adherence to fibrinogen. We demonstrated that GT-hiPSC-derived platelets recapitulate molecular and functional aspects of the disease and show comparable behavior to their native counterparts encouraging the further use of hiPSC-based disease models as well as the transition towards a clinical application. PMID:25607928

  11. Acquired platelet function defect

    MedlinePlus

    ... dark black, or tarry bowel movements ; or vomiting blood or material that looks like coffee grounds Nosebleeds ... Tests that may done include: Bleeding time Platelet aggregation test Platelet count PT and PTT

  12. The Hydraulic Permeability of Blood Clots as a Function of Fibrin and Platelet Density

    PubMed Central

    Wufsus, A.R.; Macera, N.E.; Neeves, K.B.

    2013-01-01

    Interstitial fluid flow within blood clots is a biophysical mechanism that regulates clot growth and dissolution. Assuming that a clot can be modeled as a porous medium, the physical property that dictates interstitial fluid flow is the hydraulic permeability. The objective of this study was to bound the possible values of the hydraulic permeability in clots formed in vivo and present relationships that can be used to estimate clot permeability as a function of composition. A series of clots with known densities of fibrin and platelets, the two major components of a clot, were formed under static conditions. The permeability was calculated by measuring the interstitial fluid velocity through the clots at a constant pressure gradient. Fibrin gels formed with a fiber volume fraction of 0.02–0.54 had permeabilities of 1.2 × 10−1–1.5 × 10−4μm2. Platelet-rich clots with a platelet volume fraction of 0.01–0.61 and a fibrin volume fraction of 0.03 had permeabilities over a range of 1.1 × 10−2–1.5 × 10−5μm2. The permeability of fibrin gels and of clots with platelet volume fraction of <0.2 were modeled as an array of disordered cylinders with uniform diameters. Clots with a platelet volume fraction of >0.2 were modeled as a Brinkman medium of coarse solids (platelets) embedded in a mesh of fine fibers (fibrin). Our data suggest that the permeability of clots formed in vivo can vary by up to five orders of magnitude, with pore sizes that range from 4 to 350 nm. These findings have important implications for the transport of coagulation zymogens/enzymes in the interstitial spaces during clot formation, as well as the design of fibrinolytic drug delivery strategies. PMID:23601328

  13. Measurement of platelet aggregation functions using whole blood migration ratio in a microfluidic chip.

    PubMed

    Seo, Hong Seog; Choi, Sung Hyuk; Han, Miran; Kim, Kyeong Ah; Cho, Chi Hyun; An, Seong Soo A; Lim, Chae Seung; Shin, Sehyun

    2015-09-25

    Platelets play a major role in maintaining endothelial integrity and hemostasis. Of the various soluble agonists, ADP is an important in vivo stimulus for inducing platelet aggregation. In this study, a simple, rapid, and affordable method was designed for testing bleeding time (BT) and platelet aggregation with a two-channel microfluidic chip. Whole blood migration ratio (MR) from a microchip system was evaluated in comparison to the closure time (CT) from PFA-100 assays (Siemens, Germany) and CD62P expression on platelets. To induce platelet aggregation, a combination of collagen (1.84 mg/ml) and ADP (37.5 mg/ml) were used as agonists. After adding the agonists to samples, whole blood MR from the microchip system was measured. The outcome of the assessment depended on reaction time and agonist concentration. MR of whole blood from the microchip system was significantly correlated with CT from PFA-100 (r = 0.61, p <  0.05, n = 60). In addition, MR was negatively correlated with CD62P expression (r =-0.95, p <  0.05, n = 60). These results suggest that the measurement of MR using agonists is an easy, simple and efficient method for monitoring platelet aggregation in normal and ADP-receptors defective samples, along with the BT test. Thus, usage of the current microfluidic method could expand to diverse applications, including efficacy assessments in platelet therapy. PMID:26444593

  14. Dietary manipulation of platelet function.

    PubMed

    Bachmair, E M; Ostertag, L M; Zhang, X; de Roos, B

    2014-11-01

    Activated platelets contribute to plaque formation within blood vessels in the early and late stages of atherogenesis, and therefore they have been proposed as risk factor for cardiovascular disease. Anti-platelet drugs, such as aspirin, are now the most prescribed pharmacological treatment in Europe. Certain dietary bioactives also beneficially affect platelet function, and with less side effects, albeit that effects are generally more subtle. Therefore, consumption of dietary bioactives could play a role in the prevention of atherothrombotic vascular disease. Here we review the efficacy of dietary treatment strategies, especially those involving certain dietary fatty acids and polyphenols, to modulate platelet function in healthy subjects or in patients with cardiovascular disease. Variation in study populations, small study sizes and lack of comparability between methods to assess platelet function currently limit robust evidence on the efficacy of dietary bioactives in healthy subjects or specific patient groups. Also, limited knowledge of the metabolism of dietary bioactives, and therefore of the bioavailability of bioactive ingredients, restricts our ability to identify the most effective dietary regimes to improve platelet function. Implementation of uniform point-of-care tests to assess platelet function, and enhanced knowledge of the efficacy by which specific dietary compounds and their metabolites affect platelet function, may enable the identification of functional anti-platelet ingredients that are eligible for a health claim, or combined treatment strategies, including both pharmacological anti-platelet treatment as well as dietary intervention, to tackle atherothrombotic vascular disease. PMID:24858060

  15. Human blood platelets at microgravity

    NASA Technical Reports Server (NTRS)

    Surgenor, D. MACN.; Ausprunk, D.; Blevins, D.; Chao, F. C.; Curby, W.

    1987-01-01

    A set of freshly collected and separated human platelet suspensions were transported, in three types of plastic containers, on a 6 day, 2 hr mission of the orbiter Columbia to study the effect of prolonged exposure of human blood cells to microgravity. A controlled environment at a temperature of 22 + or - 1 deg with air flow was provided and another set of samples held on the ground acted as controls. Paired comparisons of platelets at ug versus controls at lxg revealed superior platelet survival at microgravity. When viewed in terms of plastic type, ug platelets in containers fabricated from PVC-TOTM displayed the best overall postflight viability.

  16. A shear gradient-activated microfluidic device for automated monitoring of whole blood haemostasis and platelet function

    PubMed Central

    Jain, Abhishek; Graveline, Amanda; Waterhouse, Anna; Vernet, Andyna; Flaumenhaft, Robert; Ingber, Donald E.

    2016-01-01

    Accurate assessment of blood haemostasis is essential for the management of patients who use extracorporeal devices, receive anticoagulation therapy or experience coagulopathies. However, current monitoring devices do not measure effects of haemodynamic forces that contribute significantly to platelet function and thrombus formation. Here we describe a microfluidic device that mimics a network of stenosed arteriolar vessels, permitting evaluation of blood clotting within small sample volumes under pathophysiological flow. By applying a clotting time analysis based on a phenomenological mathematical model of thrombus formation, coagulation and platelet function can be accurately measured in vitro in patient blood samples. When the device is integrated into an extracorporeal circuit in pig endotoxemia or heparin therapy models, it produces real-time readouts of alterations in coagulation ex vivo that are more reliable than standard clotting assays. Thus, this disposable device may be useful for personalized diagnostics and for real-time surveillance of antithrombotic therapy in clinic. PMID:26733371

  17. A shear gradient-activated microfluidic device for automated monitoring of whole blood haemostasis and platelet function.

    PubMed

    Jain, Abhishek; Graveline, Amanda; Waterhouse, Anna; Vernet, Andyna; Flaumenhaft, Robert; Ingber, Donald E

    2016-01-01

    Accurate assessment of blood haemostasis is essential for the management of patients who use extracorporeal devices, receive anticoagulation therapy or experience coagulopathies. However, current monitoring devices do not measure effects of haemodynamic forces that contribute significantly to platelet function and thrombus formation. Here we describe a microfluidic device that mimics a network of stenosed arteriolar vessels, permitting evaluation of blood clotting within small sample volumes under pathophysiological flow. By applying a clotting time analysis based on a phenomenological mathematical model of thrombus formation, coagulation and platelet function can be accurately measured in vitro in patient blood samples. When the device is integrated into an extracorporeal circuit in pig endotoxemia or heparin therapy models, it produces real-time readouts of alterations in coagulation ex vivo that are more reliable than standard clotting assays. Thus, this disposable device may be useful for personalized diagnostics and for real-time surveillance of antithrombotic therapy in clinic. PMID:26733371

  18. Preparation of washed platelets from non-anticoagulated human blood.

    PubMed

    Bowry, S K; Müller-Berghaus, G

    1986-09-15

    Sodium citrate is almost always used to anticoagulate blood for the preparation of washed platelet suspensions. Several adverse effects of citrate on platelet functional responses have been reported. We investigated the extent of activation of platelets and plasmatic coagulation during the preparation of washed platelets from human blood to which no anticoagulant was added. Washed platelets from native blood (PNB) were prepared by passing freshly-drawn human blood rapidly through a mixed Sephadex G-25/G-50 column to remove divalent cations. Gel-filtered blood (GFB), diluted by the elution medium containing 0.35% albumin and 2U/ml apyrase, was obtained within 5 minutes of venepuncture. Using CaCl2, the GFB was found to contain a mean of 1.65 X 10 mM calcium. Fibrinopeptide A measurements indicated less activation of plasmatic coagulation in GFB than in citrated blood. Measurements of beta-thromboglobulin and platelet factor 4 during the various stages of the preparation of PNB showed no platelet activation. No platelet aggregates, as measured by the platelet aggregate ratio method, were observed in GFB. Transmission electron microscopy showed intact discoid platelets similar to those in platelet-rich plasma. The reduced activation of platelets and of plasmatic coagulation was due to the more effective removal of calcium ions from the blood by gel filtration than chelation by citrate. PNB may thus provide a model for studying the requirements for calcium in platelet function in the absence of any citrate-platelet interactions. PMID:2945282

  19. Platelet Function Tests

    MedlinePlus

    ... of the clotting process in the body ( in vivo ). A person with normal platelet function test results may still experience excessive bleeding or inappropriate clotting during and after a surgery. Most samples for platelet function testing are only stable for a very short period ...

  20. Platelet Activation Test in Unprocessed Blood (Pac-t-UB) to Monitor Platelet Concentrates and Whole Blood of Thrombocytopenic Patients

    PubMed Central

    Roest, Mark; van Holten, Thijs C.; Fleurke, Ger-Jan; Remijn, Jasper A.

    2013-01-01

    Summary Background Platelet concentrate transfusion is the standard treatment for hemato-oncology patients to compensate for thrombocytopenia. We have developed a novel platelet activation test in anticoagulated unprocessed blood (pac-t-UB) to determine platelet function in platelet concentrates and in blood of thrombocytopenic patients. Methods We have measured platelet activity in a platelet concentrate and in anticoagulated unprocessed blood of a post-transfusion thrombocytopenic patient. Results Our data show time-dependent platelet activation by GPVI agonist (collagen related peptide; CRP), PAR-1 agonist (SFLLRN), P2Y12 agonist (ADP), and thromboxane receptor agonist (U46619) in a platelet concentrate. Furthermore, pac-t-UB showed time-dependent platelet activation in unprocessed blood of a post-transfusion patient with thrombocytopenia. Testing platelet function by different agonists in relation to storage show that 3-day-old platelet concentrates are still reactive to the studied agonists. This reactivity rapidly drops for each agonists during longer storage. Discussion Pac-t-UB is a novel tool to estimate platelet function by different agonists in platelet concentrates and in unprocessed blood of thrombocytopenic patients. In the near future, we will validate whether pac-t-UB is an adequate test to monitor the quality of platelet concentrates and whether pac-t-UB predicts the bleeding risk of transfused thrombocytopenic patients. PMID:23652405

  1. Hormonal contraception and platelet function.

    PubMed

    Saleh, A A; Ginsburg, K A; Duchon, T A; Dorey, L G; Hirata, J; Alshameeri, R S; Dombrowski, M P; Mammen, E F

    1995-05-15

    73 healthy women (29 controls, 25 using OCs, and 19 using Norplant) were selected from the clinic population at North Oakland Medical Center for inclusion in this study after obtaining informed consent. Age, race, height, weight, blood pressure, and cigarette smoking were recorded for each subject. 12 patients were on monophasic OCs while 13 were on triphasic preparations. Both hormonal contraceptive groups had used their particular contraceptive for at least 3 months prior to blood drawing. Platelet tests were performed within 2 hours of sample collection: platelet counts (PLC) and mean platelet volume (MPV) were determined on an Automated Platelet Counter (Baker 810 Platelet Analyzer). Whole blood aggregation was performed on a platelet aggregometer (Chrono-Log, Model 550) using both ADP (ADP, 5 mM) and collagen (COLL, 2 mcg/ml) as inducing agents. Demographic differences were not significant (p 0.05) among the 3 treatment groups, whose average age was 25.3-25.8 years old. Furthermore, no significant differences (p 0.05) in platelet function were detected among controls or subjects receiving either oral contraceptives or Norplant, compared to control patients. The mean platelet counts (X 10/9/L) were 223 for OC users, 231 for Norplant users, and 232 for controls. The respective platelet aggregation (ADP, ohms) values were 12.5, 18.0, and 19.2 as well as (COLL, ohms) 35.6, 40.7, and 39.0. These results demonstrated that there is no evidence for altered platelet function, with the testing methods employed, in women using either Norplant or combination low dose oral contraceptives. To date, several studies have examined this issue, with contradictory reports about the effects of hormonal contraceptives in platelet function. After controlling for differences between various steroid preparations and other such confounding variables, some of these conflicting conclusions could be the result of a lack of uniformity among the methods used to evaluate platelet aggregation

  2. [Assessment of platelet function in man].

    PubMed

    Gaussem, Pascale

    2006-01-01

    Assessment of platelet function was primarily designed to explore patients with hemostatic disorders, but is becoming important for the monitoring of anti platelet agents, mostly aspirin and clopidogrel. Beside platelet counting, morphological analysis and bleeding time, a number of dedicated platelet function instruments are now available, generally allowing a rapid evaluation of platelet function in whole blood. The other tests including aggregometry and ELISA measurement of activation markers are generally restricted to specialized laboratories. Although aggregometry is still considered as the "gold standard", the recently developed flow cytometric-based platelet function analysis provides a wide choice of tests that assess the number of surface receptors, the measure of secretion and aggregation, the quantification of microparticules and leukocyte-platelet aggregates. It also allows the measure of the function of the ADP receptor P2Y12 by the phosphorylation level of the VASP protein, method currently under evaluation to monitor the platelet response to clopidogrel treatment. PMID:17243268

  3. Platelet function tests: a comparative review

    PubMed Central

    Paniccia, Rita; Priora, Raffaella; Alessandrello Liotta, Agatina; Abbate, Rosanna

    2015-01-01

    In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation – adhesion, shape change, release reaction, and aggregation – have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT) dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]). POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well-tried and innovative platelet function tests and their methodological features and clinical applications are considered. PMID:25733843

  4. Platelet Function Tests in Bleeding Disorders.

    PubMed

    Lassila, Riitta

    2016-04-01

    Functional disorders of platelets can involve any aspect of platelet physiology, with many different effects or outcomes. These include platelet numbers (thrombocytosis or thrombocytopenia); changes in platelet production or destruction, or capture to the liver (Ashwell receptor); altered adhesion to vascular injury sites and/or influence on hemostasis and wound healing; and altered activation or receptor functions, shape change, spreading and release reactions, procoagulant and antifibrinolytic activity. Procoagulant membrane alterations, and generation of thrombin and fibrin, also affect platelet aggregation. The above parameters can all be studied, but standardization and quality control of assay methods have been limited despite several efforts. Only after a comprehensive clinical bleeding assessment, including family history, information on drug use affecting platelets, and exclusion of coagulation factor, and tissue deficits, should platelet function testing be undertaken to confirm an abnormality. Current diagnostic tools include blood cell counts, platelet characteristics according to the cell counter parameters, peripheral blood smear, exclusion of pseudothrombocytopenia, whole blood aggregometry (WBA) or light transmission aggregometry (LTA) in platelet-rich plasma, luminescence, platelet function analysis (PFA-100) for platelet adhesion and deposition to collagen cartridges under blood flow, and finally transmission electron microscopy to exclude rare structural defects leading to functional deficits. The most validated test panels are included in WBA, LTA, and PFA. Because platelets are isolated from their natural environment, many simplifications occur, as circulating blood and interaction with vascular wall are omitted in these assays. The target to reach a highly specific platelet disorder diagnosis in routine clinical management can be exhaustive, unless needed for genetic counseling. The elective overall assessment of platelet function disorder

  5. Platelet function defects in chronic alcoholism.

    PubMed Central

    Mikhailidis, D P; Jenkins, W J; Barradas, M A; Jeremy, J Y; Dandona, P

    1986-01-01

    Platelet function in alcoholic patients was assessed on admission and during abstinence in hospital. On admission platelets from these patients were significantly less responsive (percentage aggregation and thromboxane A2 release) to conventional in vitro aggregating agents (adrenaline, adenosine diphosphate, and collagen) than platelets from healthy, moderate drinkers. Initially, platelet counts in platelet rich plasma tended to be low and the Simplate II bleeding times frequently prolonged. Platelet aggregation and thromboxane A2 release, however, were inhibited even in patients with normal platelet counts on admission. Platelet aggregation and thromboxane A2 release returned to normal or became hyper-responsive during two to three weeks of abstinence. Platelet counts rose during this period, the largest responses occurring in those patients with the lowest counts on admission. Bleeding times reverted to normal during abstinence and correlated significantly with changes in platelet aggregation, thromboxane A2 release, and platelet count and with the estimated ethanol consumption during the week before admission. Chronic, heavy alcohol ingestion evidently exerts an inhibitory effect on platelet function even in the absence of alcohol in the blood, and this phenomenon is reversible on abstaining. The impaired platelet function, together with the reduced platelet count, may contribute to the bleeding diathesis associated with chronic alcoholism and to the increased incidence and recurrence of gastrointestinal haemorrhage associated with excessive alcohol intake. PMID:3094624

  6. Acquisition and aggregation of canine blood platelets: basic mechanisms of function and differences because of breed origin.

    PubMed

    Clemmons, R M; Meyers, K M

    1984-01-01

    A method for obtaining reliable blood platelet yields in canine platelet-rich plasma, using increased sodium citrate concentration, is presented. Maintaining a quiet environment or anesthetizing the animals with thiamylal sodium aids in collection of platelets. Aggregation of platelets from 60 dogs of various breeds in response to arachidonic acid, collagen, adenosine diphosphate, epinephrine, and serotonin was monitored. Canine platelets reversibly or irreversibly aggregated to arachidonic acid. The percentage of arachidonate-irreversible platelets varied from 0% to 100% depending upon the breed of dogs examined. Arachidonate-irreversible platelets also aggregated irreversibly at lower concentrations of collagen and exhibited biphasic irreversible aggregation to adenosine diphosphate and serotonin. Serotonin-induced irreversible aggregation was dependent upon receptor activation and upon arachidonic acid metabolism. Irreversible aggregation to serotonin was associated with release of 3H-serotonin and thromboxane B2 formation, indicating that a couple between the serotonergic receptor and arachidonic acid metabolism may exist. PMID:6422804

  7. Platelet utilization: a Canadian Blood Services research and development symposium.

    PubMed

    Webert, Kathryn E; Alam, Asim Q; Chargé, Sophie B; Sheffield, William P

    2014-04-01

    Considerable progress has been made in recent years in understanding platelet biology and in strengthening the clinical evidence base around platelet transfusion thresholds and appropriate platelet dosing. Platelet alloimmunization rates have also declined. Nevertheless, controversies and uncertainties remain that are relevant to how these products can best be used for the benefit of platelet transfusion recipients. Platelets are unique among the blood products directly derived from whole blood or apheresis donations in requiring storage, with shaking, at ambient temperature. Storage is accordingly constrained between the need to limit the growth of any microbes in the product and the need to minimize losses in platelet function associated with storage. Proteomic and genomic approaches are being applied to the platelet storage lesion. Platelet inventory management is made challenging by these constraints. Although bacterial screening has enhanced the safety of platelet transfusions, pathogen reduction technology may offer further benefits. Continuing clinical investigations are warranted to understand the value of transfusing platelets prophylactically or only in response to bleeding in different patient groups and how best to manage the most grievously injured trauma patients. Patients refractory to platelet transfusions also require expert clinical management. The engineering of platelet substitute products is an active area of research, but considerable hurdles remain before any clinical uses may be contemplated. Roles for platelets in biological areas distinct from hemostasis are also emerging. Platelet utilization is variably affected by all of the above factors, by demographic changes, by new medications, and by new patient care approaches. PMID:24629305

  8. The role of peroxides as modulators of human blood platelet function

    SciTech Connect

    Jesse, R.L.; Hess, M.L. )

    1990-02-26

    The ability to peroxidize lipid in the vicinity of arterial walls has been demonstrated through oxidation of the LDL-particle by monocytes/macrophages, smooth muscle cells, and endothelial cells. The authors questioned what effect increased levels of peroxides might have on platelet function. Platelet aggregation, studied trubidometrically, was initiated by arachidonic acid (AA) alone or in the presence of a low concentration of H{sub 2}O{sub 2}, (which by itself could not initiate aggregation). Aggregation was analyzed quantitatively by measuring the time it took to reach 1/2 the maximal extent of aggregation (T1/2Max). Using the minimal concentration of AA still able to initiate aggregation (0.2-0.45 mM) the T1/2Max was 112{+-}35 (n=10). With 50% of the respective AA conc. plus 17 {mu}M H{sub 2}O{sub 2}, the T1/2Max was 52{+-}21. Under similar circumstances, the amount of AA able to initiate aggregation could be reduced by 80% with the addition of H{sub 2}O{sub 2}. These effects could be duplicated by glucose oxidase, 0.015-0.15 IU, and could be eliminated by the addition of catalase (<25 U/ml) at any time prior to the start of aggregation. With non-aggregating concentrations of AA alone, synthesis of Thromboxane B{sub 2} was negligible; with aggregation by the same AA plus H{sub 2}O{sub 2} it was 550{+-}79 pg/10{sup 3} platelets. Both aggregation and TxB{sub 2} synthesis were completely inhibited by aspirin or indomethacin, and by the antioxidants phenol and nor-dihydroguaretic acid, at concentrations known to inhibit cyclooxygenase. In platelets with a defect in the second wave of ADP induced aggregation, but having normal aggregation with added AA (indicating the cyclooxygenase-thromboxane axis was intact), sub-aggregating concentrations of AA, plus H{sub 2}O{sub 2} resulted in brisk aggregation.

  9. Failure of platelet parameters and biomarkers to correlate platelet function to severity and etiology of heart failure in patients enrolled in the EPCOT trial. With special reference to the Hemodyne hemostatic analyzer. Whole Blood Impedance Aggregometry for the Assessment of Platelet Function in Patients with Congestive Heart Failure.

    PubMed

    Serebruany, Victor L; McKenzie, Marcus E; Meister, Andrew F; Fuzaylov, Sergey Y; Gurbel, Paul A; Atar, Dan; Gattis, Wendy A; O'Connor, Christopher M

    2002-01-01

    Data from small studies have suggested the presence of platelet abnormalities in patients with congestive heart failure (CHF). We sought to characterize the diagnostic utility of different platelet parameters and platelet-endothelial biomarkers in a random outpatient CHF population investigated in the EPCOT ('Whole Blood Impedance Aggregometry for the Assessment of Platelet Function in Patients with Congestive Heart Failure') Trial. Blood samples were obtained for measurement of platelet contractile force (PCF), whole blood aggregation, shear-induced closure time, expression of glycoprotein (GP) IIb/IIIa, and P-selectin in 100 consecutive patients with CHF. Substantial interindividual variability of platelet characteristics exists in patients with CHF. There were no statistically significant differences when patients were grouped according to incidence of vascular events, emergency revascularization needs, survival, or etiology of heart failure. Aspirin use did not affect instrument readings either. PCF correlates very poorly with whole blood aggregometry (r(2) = 0.023), closure time (r(2) = 0.028), platelet GP IIb/IIIa (r(2) = 0.0028), and P-selectin (r(2) = 0.002) expression. Furthermore, there was no correlation with brain natriuretic peptide concentrations, a marker of severity and prognosis in heart failure reflecting the neurohumoral status. Patients with heart failure enrolled in the EPCOT Trial exhibited a marginal, sometimes oppositely directed change in platelet function, challenging the diagnostic utility of these platelet parameters and biomarkers to serve as useful tools for the identification of platelet abnormalities, for predicting clinical outcomes, or for monitoring antiplatelet strategies in this population. The usefulness of these measurements for assessing platelets in the different clinical settings remains to be explored. Taken together, opposite to our expectations, major clinical characteristics of heart failure did not correlate well with

  10. Rupture Forces among Human Blood Platelets at different Degrees of Activation.

    PubMed

    Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

    2016-01-01

    Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects. PMID:27146004

  11. Rupture Forces among Human Blood Platelets at different Degrees of Activation

    PubMed Central

    Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

    2016-01-01

    Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects. PMID:27146004

  12. Microfluidics for simultaneous quantification of platelet adhesion and blood viscosity

    PubMed Central

    Yeom, Eunseop; Park, Jun Hong; Kang, Yang Jun; Lee, Sang Joon

    2016-01-01

    Platelet functions, including adhesion, activation, and aggregation have an influence on thrombosis and the progression of atherosclerosis. In the present study, a new microfluidic-based method is proposed to estimate platelet adhesion and blood viscosity simultaneously. Blood sample flows into an H-shaped microfluidic device with a peristaltic pump. Since platelet aggregation may be initiated by the compression of rotors inside the peristaltic pump, platelet aggregates may adhere to the H-shaped channel. Through correlation mapping, which visualizes decorrelation of the streaming blood flow, the area of adhered platelets (APlatelet) can be estimated without labeling platelets. The platelet function is estimated by determining the representative index IA·T based on APlatelet and contact time. Blood viscosity is measured by monitoring the flow conditions in the one side channel of the H-shaped device. Based on the relation between interfacial width (W) and pressure ratio of sample flows to the reference, blood sample viscosity (μ) can be estimated by measuring W. Biophysical parameters (IA·T, μ) are compared for normal and diabetic rats using an ex vivo extracorporeal model. This microfluidic-based method can be used for evaluating variations in the platelet adhesion and blood viscosity of animal models with cardiovascular diseases under ex vivo conditions. PMID:27118101

  13. Microfluidics for simultaneous quantification of platelet adhesion and blood viscosity.

    PubMed

    Yeom, Eunseop; Park, Jun Hong; Kang, Yang Jun; Lee, Sang Joon

    2016-01-01

    Platelet functions, including adhesion, activation, and aggregation have an influence on thrombosis and the progression of atherosclerosis. In the present study, a new microfluidic-based method is proposed to estimate platelet adhesion and blood viscosity simultaneously. Blood sample flows into an H-shaped microfluidic device with a peristaltic pump. Since platelet aggregation may be initiated by the compression of rotors inside the peristaltic pump, platelet aggregates may adhere to the H-shaped channel. Through correlation mapping, which visualizes decorrelation of the streaming blood flow, the area of adhered platelets (APlatelet) can be estimated without labeling platelets. The platelet function is estimated by determining the representative index IA·T based on APlatelet and contact time. Blood viscosity is measured by monitoring the flow conditions in the one side channel of the H-shaped device. Based on the relation between interfacial width (W) and pressure ratio of sample flows to the reference, blood sample viscosity (μ) can be estimated by measuring W. Biophysical parameters (IA·T, μ) are compared for normal and diabetic rats using an ex vivo extracorporeal model. This microfluidic-based method can be used for evaluating variations in the platelet adhesion and blood viscosity of animal models with cardiovascular diseases under ex vivo conditions. PMID:27118101

  14. The effects of cytochalasin D and abciximab on hemostasis in canine whole blood assessed by thromboelastography and the PFA-100® platelet function analyzer system.

    PubMed

    Brainard, Benjamin M; Abed, Janan M; Koenig, Amie

    2011-07-01

    The selective inhibition of platelet function in whole blood coagulation testing may allow insights into the nature of hypercoagulability in dogs with critical illness. To determine the effects of cytochalasin D and abciximab on hemostatic parameters in canine citrated whole blood, an in-vitro study was designed using thromboelastography (TEG) and a platelet function analyzer (PFA-100®). 8 clinically healthy mixed breed dogs donated blood that was anticoagulated with 3.2% sodium citrate in a 9:1 blood-to-citrate ratio. Addition of cytochalasin D to citrated whole blood from 6 dogs at concentrations ranging from 0 µg/ml to 10 µg/ml caused a maximal reduction of TEG maximum amplitude (MA) at a concentration of 7.5 µg/ml (52.7 ± 4.3 to 14.3 ± 7.8 mm). Addition of abciximab to canine citrated whole blood at concentrations of either 20 µg/ml or 40 µg/ml did not affect the TEG tracing; however, addition of abciximab to citrated canine whole blood at concentrations of 10 µg/ml and 20 µg/ml significantly prolonged PFA-100 closure times (72.5 ± 15 to 149.2 ± 91 sec and 275.6 ± 54 sec, respectively, P < 0.04). Inhibition of canine platelet function by cytochalasin D is demonstrated by TEG, but abciximab did not change TEG tracings. Abciximab does, however, inhibit platelet aggregation under shear stress as measured by the PFA-100. Inhibition of canine platelet function with cytochalasin D may allow further TEG studies in dogs with clinical disease. PMID:21908311

  15. Extending The Shelf Life Of Blood Platelets

    NASA Technical Reports Server (NTRS)

    Surgenor, Douglas M.

    1988-01-01

    New method of storing human blood platelets extends vitality for transfusions. Packaged as suspension in sterile liquid in plastic blood bags. Each bag placed between pair of plastic grids, and rubberbands placed around sandwich thus formed to hold together. Stored upright in open air or in container through which air pumped at rate of at least 45 L/min. Ensures that platelets receive ample oxygen and expiratory carbon dioxide form platelets removed before pH drops to harmful levels.

  16. Assessment of blood clot formation and platelet receptor function ex vivo in patients with primary Sjögren's syndrome

    PubMed Central

    Collins, K S; Balasubramaniam, K; Viswanathan, G; Natasari, A; Tarn, J; Lendrem, D; Mitchell, S; Zaman, A; Ng, W F

    2013-01-01

    Objectives Primary Sjögren's syndrome (pSS) shares clinical features and pathogenetic mechanisms with systemic lupus erythematosus (SLE). SLE is associated with an increased thromboembolic risk; however, it is unclear whether pSS patients are susceptible to thromboembolic diseases. In this study, we examined ex vivo blood clot formation (clot strength, rates of clot formation and lysis) in pSS using thromboelastography (TEG) and platelet aggregation to common agonists using multiple electrode aggregometry (MEA). We also investigated the relationship between TEG/MEA parameters and clinical/laboratory features of pSS. Design Case control. Setting Secondary care, single centre. Participants 34 pSS patients, 11 SLE patients and 13 healthy volunteers (all women) entered and completed the study. Primary and secondary outcome measures Primary outcomes: TEG and MEA parameters between three subject groups. Secondary outcomes: The relationships between TEG/MEA and clinical/laboratory parameters analysed using bivariate correlation analysis with corrections for multiple testing. Results All TEG and MEA parameters were similar for the three subject groups. After corrections for multiple testing, interleukin (IL)-1α and Macrophage inflammatory proteins (MIP)-1α remain correlated inversely with clot strength (r=−0.686, p=0.024 and r=−0.730, p=0.012, respectively) and overall coagulability (r=−0.640, p=0.048 and r=−0.648, p=0.048). Stepwise regression analysis revealed that several cytokines such as MIP-1α, IL-17a, IL-1α and Interferon (IFN)-γ may be key predictors of clot strength and overall coagulability in pSS. Conclusions Clot kinetics and platelet receptor function are normal in pSS. Several cytokines correlate with clot strength and overall coagulability in pSS. PMID:23793707

  17. Congenital platelet function defects

    MedlinePlus

    Kottke-Marchant K. Platelet disorders. In: Hsi ED, ed. Hematopathology . 2nd ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 2. Nichols WL. Von Willebrand disease and hemorrhagic abnormalities of platelet ...

  18. Platelet aggregation test

    MedlinePlus

    The platelet aggregation blood test checks how well platelets , a part of blood, clump together and cause blood to clot. ... Decreased platelet aggregation may be due to: Autoimmune ... Fibrin degradation products Inherited platelet function defects ...

  19. Mapuche Herbal Medicine Inhibits Blood Platelet Aggregation

    PubMed Central

    Falkenberg, Susan Skanderup; Tarnow, Inge; Guzman, Alfonso; Mølgaard, Per; Simonsen, Henrik Toft

    2012-01-01

    12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM) and collagen- (2.0 μg/mL) induced aggregations in human blood. These four species in respective extracts (in brackets) were Blechnum chilense (MeOH), Luma apiculata (H2O), Amomyrtus luma (DCM : MeOH 1 : 1) and Cestrum parqui (DCM : MeOH 1 : 1). The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1), and L. apiculata (H2O) were substantial and confirmed by inhibition of platelet surface activation markers. PMID:22028732

  20. Mapuche herbal medicine inhibits blood platelet aggregation.

    PubMed

    Falkenberg, Susan Skanderup; Tarnow, Inge; Guzman, Alfonso; Mølgaard, Per; Simonsen, Henrik Toft

    2012-01-01

    12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM) and collagen- (2.0 μg/mL) induced aggregations in human blood. These four species in respective extracts (in brackets) were Blechnum chilense (MeOH), Luma apiculata (H(2)O), Amomyrtus luma (DCM : MeOH 1 : 1) and Cestrum parqui (DCM : MeOH 1 : 1). The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1), and L. apiculata (H(2)O) were substantial and confirmed by inhibition of platelet surface activation markers. PMID:22028732

  1. Microfluidic Flow Chambers Using Reconstituted Blood to Model Hemostasis and Platelet Transfusion In Vitro.

    PubMed

    Van Aelst, Britt; Feys, Hendrik B; Devloo, Rosalie; Vandekerckhove, Philippe; Compernolle, Veerle

    2016-01-01

    Blood platelets prepared for transfusion gradually lose hemostatic function during storage. Platelet function can be investigated using a variety of (indirect) in vitro experiments, but none of these is as comprehensive as microfluidic flow chambers. In this protocol, the reconstitution of thrombocytopenic fresh blood with stored blood bank platelets is used to simulate platelet transfusion. Next, the reconstituted sample is perfused in microfluidic flow chambers which mimic hemostasis on exposed subendothelial matrix proteins. Effects of blood donation, transport, component separation, storage and pathogen inactivation can be measured in paired experimental designs. This allows reliable comparison of the impact every manipulation in blood component preparation has on hemostasis. Our results demonstrate the impact of temperature cycling, shear rates, platelet concentration and storage duration on platelet function. In conclusion, this protocol analyzes the function of blood bank platelets and this ultimately aids in optimization of the processing chain including phlebotomy, transport, component preparation, storage and transfusion. PMID:27023054

  2. Characteristics of rat platelets and relative contributions of platelets and blood coagulation to haemostasis.

    PubMed

    Takahashi, O

    2000-01-01

    In order to understand some of the haemostatic mechanisms in rats for the interpretation of toxicological data, basic haemostatic parameters with a special emphasis on platelet functions were first measured in vitro. The results of reactions of rat platelets to many aggregating agents suggest that only ADP may be a consistently significant aggregator. The search for physiologic aggregators revealed ADP to be available from erythrocytes. Adhesion reaction also required ADP. Collagen was not considered to be essential for either reaction. Aggregation and adhesion were probably both reversible in flowing blood, while irreversible thrombi were formed in blood at rest ex vivo. Blood coagulation parameters determined revealed that the intrinsic pathway may be more important than the extrinsic one. The rate of intrinsic coagulation reaction was rapid, and plasma coagulation appeared to be of primary importance while the influence of platelet aggregation was minor. A simple model of rat haemostatic mechanism is proposed based on these results. Additionally, to define the relative contribution of platelets versus other cellular and plasma coagulation in vivo, rats were administered antiplatelet drugs (ticlopidine, suprofen and clopidogrel) and an anticoagulant (warfarin) intraperitoneally. Bleeding times (BTs) were significantly increased in all treated groups. ADP-induced platelet aggregations were significantly depressed by the administration of the three antiplatelet drugs, while kaolon-activated partial thromboplastin time and prothrombin time were greatly increased in the warfarin-treated rats. The increase in BT may be due to the inhibition of platelet activity or blood coagulation defect in rats given antiplatelet drugs or warfarin, respectively. These results suggest that platelets play a key role in haemostasis in the rat. Two possible explanations of the disparity between in vitro and in vivo results may be that functional tests used here are not adequate to cover

  3. Effects of irradiation on platelet function

    SciTech Connect

    Rock, G.; Adams, G.A.; Labow, R.S.

    1988-09-01

    Current medical practice involves the irradiation of blood components, including platelet concentrates, before their administration to patients with severe immunosuppression. The authors studied the effect of irradiation on in vitro platelet function and the leaching of plasticizers from the bag, both immediately and after 5 days of storage. The platelet count, white cell count, pH, glucose, lactate, platelet aggregation and release reaction, and serotonin uptake were not altered by the irradiation of random-donor or apheresis units with 2000 rads carried out at 0 and 24 hours and 5 days after collection. The leaching of di(2-ethylhexyl)phthalate from the plastic bags followed by the conversion to mono(2-ethylhexyl)phthalate was not increased by irradiation. Therefore, it is possible to irradiate platelet concentrates on the day of collection and subsequently store them for at least 5 days while maintaining in vitro function. This procedure could have considerable benefit for blood banks involved in the provision of many platelet products.

  4. Platelet function tests, independent of platelet count, are associated with bleeding severity in ITP

    PubMed Central

    Grace, Rachael F.; Gerrits, Anja J.; Berny-Lang, Michelle A.; Brown, Travis; Carmichael, Sabrina L.; Neufeld, Ellis J.; Michelson, Alan D.

    2015-01-01

    Immune thrombocytopenia (ITP) patients with similarly low platelet counts differ in their tendency to bleed. To determine if differences in platelet function in ITP patients account for this variation in bleeding tendency, we conducted a single-center, cross-sectional study of pediatric patients with ITP. Bleeding severity (assessed by standardized bleeding score) and platelet function (assessed by whole blood flow cytometry) with and without agonist stimulation was evaluated in 57 ITP patients (median age, 9.9 years). After adjustment for platelet count, higher levels of thrombin receptor activating peptide (TRAP)-stimulated percent P-selectin- and activated glycoprotein (GP)IIb-IIIa–positive platelets were significantly associated with a lower bleeding score, whereas higher levels of immature platelet fraction (IPF), TRAP-stimulated platelet surface CD42b, unstimulated platelet surface P-selectin, and platelet forward light scatter (FSC) were associated with a higher bleeding score. Thus, platelet function tests related to platelet age (IPF, FSC) and activation through the protease activated receptor 1 (PAR1) thrombin receptor (TRAP-stimulated P-selectin, activated GPIIb-IIIa, and CD42b), independent of platelet count, are associated with concurrent bleeding severity in ITP. These tests may be useful markers of future bleeding risk in ITP. PMID:26138687

  5. In vivo effects of eltrombopag on platelet function in immune thrombocytopenia: no evidence of platelet activation

    PubMed Central

    Psaila, Bethan; Bussel, James B.; Linden, Matthew D.; Babula, Bracken; Li, Youfu; Barnard, Marc R.; Tate, Chinara; Mathur, Kanika; Frelinger, Andrew L.

    2012-01-01

    The effects of eltrombopag, a thrombopoietin-receptor agonist, on platelet function in immune thrombocytopenia (ITP) are not fully characterized. This study used whole blood flow cytometry to examine platelet function in 20 patients receiving eltrombopag treatment at days 0, 7, and 28. Platelet surface expression of activated GPIIb/IIIa, P-selectin, and GPIb was measured with and without low and high adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP) concentrations. Before eltrombopag treatment with no ex vivo agonist, platelet activation was higher in ITP patients than controls. Platelet GPIb and activated GPIIb/IIIa expression without added agonist was unchanged following eltrombopag treatment, whereas a slight increase in P-selectin was observed. Expression of P-selectin and activated GPIIb/IIIa in response to high-dose ADP was lower during eltrombopag treatment than at baseline. Eltrombopag led to a slight increase in platelet reactivity to TRAP only in responders to eltrombopag but not to levels above those in controls; whole blood experiments demonstrated that this increase was probably because of higher platelet counts rather than higher platelet reactivity. In conclusion, although thrombocytopenic ITP patients have higher baseline platelet activation than controls, eltrombopag did not cause platelet activation or hyper-reactivity, irrespective of whether the platelet count increased. PMID:22294727

  6. Transport of platelets in flowing blood.

    PubMed

    Eckstein, E C; Bilsker, D L; Waters, C M; Kippenhan, J S; Tilles, A W

    1987-01-01

    Distribution and transport of platelets in flowing blood were studied experimentally using suspensions of washed red cells and fluorescent latex beads as platelet analogues. Distributions of the platelet analogues were obtained from stroboscopic epifluorescence photomicrographs of flow in 50-micron channels and from images of the cut cross sections of cryogenically frozen thin-walled 200-micron tubes. Concentration profiles of platelet analogues had a substantial near-wall excess for situations with a substantial hematocrit (greater than 10%) and a substantial wall shear rate (greater than 400 s-1). The viscosity of the suspending fluid was found to affect the size of the near-wall excess and its shear-dependent onset. Additionally, the shear-rate dependence of the near-wall excess did not occur with suspensions of hardened red cells. The excess extended a substantial distance from the wall in the 200-micron tubes and a portion of the profile could be fitted to an exponential curve. The random walk model that is used to describe enhanced platelet diffusion is envisioned as a walk (lateral platelet motion) caused by shear-induced collisions with red cells. A more comprehensive random walk model that includes biased collisions produces an effective lateral motion of convective nature in addition to a diffusional motion; it is used to explain the observed nonuniform distributions of platelet analogues. PMID:3439741

  7. Generation of mesenchymal stromal cells in the presence of platelet lysate: a phenotypic and functional comparison of umbilical cord blood- and bone marrow-derived progenitors

    PubMed Central

    Avanzini, Maria Antonietta; Bernardo, Maria Ester; Cometa, Angela Maria; Perotti, Cesare; Zaffaroni, Nadia; Novara, Francesca; Visai, Livia; Moretta, Antonia; Del Fante, Claudia; Villa, Raffaella; Ball, Lynne M.; Fibbe, Willem E.; Maccario, Rita; Locatelli, Franco

    2009-01-01

    Background Mesenchymal stromal cells are employed in various different clinical settings in order to modulate immune response. However, relatively little is known about the mechanisms responsible for their immunomodulatory effects, which could be influenced by both the cell source and culture conditions. Design and Methods We tested the ability of a 5% platelet lysate-supplemented medium to support isolation and ex vivo expansion of mesenchymal stromal cells from full-term umbilical-cord blood. We also investigated the biological/functional properties of umbilical cord blood mesenchymal stromal cells, in comparison with platelet lysate-expanded bone marrow mesenchymal stromal cells. Results The success rate of isolation of mesenchymal stromal cells from umbilical cord blood was in the order of 20%. These cells exhibited typical morphology, immunophenotype and differentiation capacity. Although they have a low clonogenic efficiency, umbilical cord blood mesenchymal stromal cells may possess high proliferative potential. The genetic stability of these cells from umbilical cord blood was demonstrated by a normal molecular karyotype; in addition, these cells do not express hTERT and telomerase activity, do express p16ink4a protein and do not show anchorage-independent cell growth. Concerning alloantigen-specific immune responses, umbilical cord blood mesenchymal stromal cells were able to: (i) suppress T- and NK-lymphocyte proliferation, (ii) decrease cytotoxic activity and (iii) only slightly increase interleukin-10, while decreasing interferon-γ secretion, in mixed lymphocyte culture supernatants. While an indoleamine 2,3-dioxygenase-specific inhibitor did not reverse mesenchymal stromal cell-induced suppressive effects, a prostaglandin E2-specific inhibitor hampered the suppressive effect of both umbilical cord blood- and bone marrow-mesenchymal stromal cells on alloantigen-induced cytotoxic activity. Mesenchymal stromal cells from both sources expressed HLA

  8. Changes in platelet function following cold storage of RBC suspensions

    PubMed Central

    Dang, Qian-Li; Li, Jian-Gang; Sun, Yang; Jin, Zhan-Kui; Gao, Ying; Xu, Cui-Xiang; Chen, Ping; Ma, Ting; Yang, Jiang-Cun

    2015-01-01

    Objective: To provide a basis for the cold-storage of human platelets as a way to assess changes in platelet function. Methods: Red blood cell suspensions (11 U and 50 U) were randomly selected at different storage times (3-28 days) and evidence of platelet activation (CD62P) and thromboelastography (TEG) reaction times were investigated. Results: After 21 days of storage at 4°C, a large number of activated platelets (PAC1+62P+, PAC1-62P+) within the red blood cell suspension (RBCs) retained their function and had TEG-maximum amplitude (TEG-MA) indices in the normal range. Conclusion: We report that platelets in RBC suspensions retain high activity when stored at 4°C for 21 days. The results provide important information for studies that involve storing platelets under cold conditions. PMID:26770402

  9. Effects of argon laser on in vitro aggregation of platelets in platelet rich plasma and whole blood

    SciTech Connect

    Doerger, P.T.; Glueck, H.I.; McGill, M.

    1988-06-01

    The effects of an Argon laser on platelet aggregation were studied, since platelets may be exposed to laser energy when used intravascularly. Various preparations of platelets in platelet rich plasma (PRP) and whole blood, with or without aspirin, were tested with the aggregating agents ADP, collagen, thrombin, and epinephrine. Simultaneous release of ATP was also measured in PRP. At relatively low levels of irradiation, platelet aggregation was potentiated. Enhancement was evidenced by an increase in percent aggregation, earlier onset of the reaction, and reduction in the amount of aggregating agent required. In PRP, the mechanism of laser potentiation appeared to be the release of endogenous ATP from platelets. At relatively high levels of irradiation, platelets were destroyed and aggregation abolished. In whole blood, the mechanism was somewhat more complicated since release of ATP occurred from RBCs as well as platelets. Spontaneous aggregation following laser treatment occurred in isolated instances in PRP and in every trial in whole blood preparations. Aspirin ingestion inhibited the laser's effects in PRP but not in whole blood. These results may have important clinical implications for laser angioplasty, and the potentiated aggregation response may prove useful in laboratory studies of platelet function.

  10. Antioxidant and antiaggregatory effects of an extract from Conyza canadensis on blood platelets in vitro.

    PubMed

    Olas, Beata; Saluk-Juszczak, Joanna; Pawlaczyk, Izabela; Nowak, Pawel; Kolodziejczyk, Joanna; Gancarz, Roman; Wachowicz, Barbara

    2006-09-01

    The antioxidative activity of the polysaccharide extract from Conyza canadensis in blood platelets treated with peroxynitrite (ONOO-) was studied. Peroxynitrite as a strong biological oxidant has toxic effects on blood platelets and induces the oxidation of thiols, carbonylation and nitration of platelet proteins and lipid peroxidation. Therefore, the aim of our study was to assess if the natural extract from herbal plant, Conyza Canadensis, may protect platelet proteins against nitrative and oxidative damage induced by ONOO-. In our study we measured oxidative damage of platelet proteins induced by peroxynitrite and protectory effects of this extract by estimation of the level of carbonyl groups and nitrotyrosine (a marker of platelet protein nitration). We also used cytochrome c reduction method to test the ability of this extract to change O2-* generation in platelets. Moreover, we determined the effects of the extract on blood platelet aggregation induced by ADP. We observed that the extract from Conyza canadensis distinctly reduced oxidation and nitration of proteins in blood platelets treated with ONOO-(0.1mM) and O2-* production in these cells. The extract from Conyza canadensis also inhibited platelet aggregation. The ability of the extract to decrease O2-* generation in blood platelets supports the importance of free radicals in platelet functions, including aggregation process. The present study suggests that the natural polysaccharide extract from Conyza canadensis has antiaggregatory and antioxidative activities, and therefore may be beneficial in the prevention of peroxynitrite-related diseases, such as cardiovascular or inflammatory diseases. PMID:16973495

  11. Acquired platelet function defect

    MedlinePlus

    ... on the skin Gastrointestinal bleeding resulting in bloody, dark black, or tarry bowel movements ; or vomiting blood ... to the principles of the Health on the Net Foundation (www.hon.ch). The information provided herein ...

  12. Effect of Platelet-Rich Plasma (PRP) versus Autologous Whole Blood on Pain and Function Improvement in Tennis Elbow: A Randomized Clinical Trial

    PubMed Central

    Raeissadat, Seyed Ahmad; Sedighipour, Leyla; Rayegani, Seyed Mansoor; Bahrami, Mohammad Hasan; Bayat, Masume; Rahimi, Rosa

    2014-01-01

    Background. Autologous whole blood and platelet-rich plasma (PRP) have been both suggested to treat chronic tennis elbow. The aim of the present study was to compare the effects of PRP versus autologous whole blood local injection in chronic tennis elbow. Methods. Forty patients with tennis elbow were randomly divided into 2 groups. Group 1 was treated with a single injection of 2 mL of autologous PRP and group 2 with 2 mL of autologous blood. Tennis elbow strap, stretching, and strengthening exercises were administered for both groups during a 2-month followup. Pain and functional improvements were assessed using visual analog scale (VAS), modified Mayo Clinic performance index for the elbow, and pressure pain threshold (PPT) at 0, 4, and 8 weeks. Results. All pain and functional variables including VAS, PPT, and Mayo scores improved significantly in both groups 4 weeks after injection. No statistically significant difference was noted between groups regarding pain scores in 4-week follow-up examination (P > 0.05). At 8-week reevaluations, VAS and Mayo scores improved only in PRP group (P < 0.05). Conclusion. PRP and autologous whole blood injections are both effective to treat chronic lateral epicondylitis. PRP might be slightly superior in 8-week followup. However, further studies are suggested to get definite conclusion. PMID:24579044

  13. Overview of platelet physiology and laboratory evaluation of platelet function.

    PubMed

    Rodgers, G M

    1999-06-01

    Appropriate laboratory testing for the platelet-type bleeding disorders hinges on an adequate assessment in the history and physical examination. Patients with histories and screening laboratory results consistent with coagulation disorders (hemophilia, disseminated intravascular coagulation) are not appropriate candidates for platelet function testing. In contrast, patients with a lifelong history of platelet-type bleeding symptoms and perhaps a positive family history of bleeding would be appropriate for testing. Figure 6 depicts one strategy to evaluate these patients. Platelet morphology can easily be evaluated to screen for two uncommon qualitative platelet disorders: Bernard-Soulier syndrome (associated with giant platelets) and gray platelet syndrome, a subtype of storage pool disorder in which platelet granulation is morphologically abnormal by light microscopy. If the bleeding disorder occurred later in life (no bleeding with surgery or trauma early in life), the focus should be on acquired disorders of platelet function. For those patients thought to have an inherited disorder, testing for vWD should be done initially because approximately 1% of the population has vWD. The complete vWD panel (factor VIII coagulant activity, vWf antigen, ristocetin cofactor activity) should be performed because many patients will have abnormalities of only one particular panel component. Patients diagnosed with vWD should be classified using multimeric analysis to identify the type 1 vWD patients likely to respond to DDAVP. If vWD studies are normal, platelet aggregation testing should be performed, ensuring that no antiplatelet medications have been ingested at least 1 week before testing. If platelet aggregation tests are normal and if suspicion for an inherited disorder remains high, vWD testing should be repeated. The evaluation of thrombocytopenia may require bone marrow examination to exclude primary hematologic disorders. If future studies with thrombopoietin assays

  14. Dynamic light scattering can determine platelet function

    NASA Astrophysics Data System (ADS)

    Lee, Nathan

    2011-10-01

    Platelet transfusions are life-saving procedures for patients who are bleeding or undergoing chemotherapy. The effectiveness of transfusions depends on the number of platelets transfused and the platelet function. Platelet function correlates with proportion of discoid to activated platelets, morphology response to temperature stress, and inversely correlates with microparticle content. ThromboLUX is a novel device that determines platelet function by measuring all of these characteristics using dynamic light scattering (DLS). During periods of stress, such as decreased temperature, cytoskeletal rearrangements will cause normal, discoid platelets to activate and become spiny spheres. The formation of pseudopods of various lengths facilitates the clotting cascade and also increases the apparent size of platelets. ThromboLUX uses a 37-20-37 C temperature cycle that mimics the bleeding, storage, and transfusion process. As the temperature fluctuates, DLS will measure the changing platelet hydrodynamic radius and the size of any microparticles present. ThromboLUX analysis of platelet concentrates in vitro would allow determination of high platelet function units before transfusion and would therefore improve transfusion outcomes and patient safety. This study examined how DLS is able to distinguish between discoid and activated platelets as well as measure the parameters that contribute to high platelet function.

  15. Effect of circulating epinephrine on platelet function and hematocrit.

    PubMed

    Kjeldsen, S E; Weder, A B; Egan, B; Neubig, R; Zweifler, A J; Julius, S

    1995-05-01

    We investigated the effect of raising arterial plasma epinephrine within the lower pathophysiological concentration range on various indicators of blood platelet function and hematocrit. Epinephrine was raised over 60 minutes by a stepwise increasing intravenous infusion in 40 healthy men aged 20 to 40 years. Platelet count increased progressively with increasing arterial epinephrine to a maximal change of 69 +/- 6 x 10(9)/L in EDTA-anticoagulated blood and a maximal change of 42 +/- 6 x 10(9)/L in acid-citrate-dextrose (ACD)-anticoagulated blood, and the weight of circulating platelets increased by 29% (P < .001). Platelet size increased significantly in EDTA and decreased in ACD, and the difference between EDTA and ACD was significant (P < .0001) for both count and size, suggesting that epinephrine not only recruits platelets into the circulation but also induces some microaggregation in vivo or adhesion ex vivo. Aggregation of platelets in vitro induced by epinephrine decreased (P < .003 for delta optical density and P = .038 for maximal optical density) after epinephrine infusion compared with saline but did not change when stimulated with ADP or collagen. These findings suggest a selective downregulation of the epinephrine-activating mechanisms concomitant with a rise in the platelet content of epinephrine by 81% (P < .001) and no change in the platelet sodium-proton membrane exchange. The release of granular content (beta-thromboglobulin and platelet factor 4) to the circulation in response to epinephrine was not significant. Thus, under acute conditions it seems that the platelets may protect themselves against inappropriate overstimulation by epinephrine. The importance of platelet epinephrine uptake is still unknown, but sodium-proton exchange does not seem to be involved in regulating the effects of circulating epinephrine on platelet function. Epinephrine has a pronounced effect on raising hematocrit (maximal change of 1.74 +/- 0.13 x 10(-2), P < .0001

  16. Comparative rheology of the adhesion of platelets and leukocytes from flowing blood: why are platelets so small?

    PubMed

    Watts, Tim; Barigou, Mostafa; Nash, Gerard B

    2013-06-01

    We investigated rheological adaptation of leukocytes and platelets for their adhesive functions in inflammation and hemostasis, respectively. Adhesion and margination of leukocytes or platelets were quantified for blood perfused through capillaries coated with P-selectin or collagen, when flow rate, suspending phase viscosity, red cell aggregation, or rigidity was modified. Independent variation of shear rate and shear stress indicated that the ability of platelets to attach at higher levels than leukocytes was largely attributable to their smaller size, reducing their velocity before attachment, and, especially, drag after attachment. Increasing red cell aggregation increased the number of marginated and adhering leukocytes but inhibited platelet adhesion without effect on the number marginated. Increasing red cell rigidity tended to inhibit leukocyte adhesion but promote platelet adhesion. The effects on platelets may be explained by changes in the depth of the near-wall, red cell-depleted layer; broadening (or narrowing) this layer to greater (or less) than the platelet diameter would decrease (or increase) the normal force applied by red blood cells and make attachment less (or more) efficient. Thus different adhesive capabilities of leukocytes and platelets may arise from their differences in size, both directly because of influence on cell velocity and force experienced at the wall and indirectly through effects of size on margination in the bloodstream and interaction with the cell-free layer. In addition, red cell aggregation (of hitherto uncertain physiological significance) may be useful in promoting leukocyte adhesion in inflamed venules but inhibiting unwanted platelet deposition in veins. PMID:23585130

  17. Blood coagulation and platelet adhesion on polyaniline films.

    PubMed

    Humpolíček, Petr; Kuceková, Zdenka; Kašpárková, Věra; Pelková, Jana; Modic, Martina; Junkar, Ita; Trchová, Miroslava; Bober, Patrycja; Stejskal, Jaroslav; Lehocký, Marián

    2015-09-01

    Polyaniline is a promising conducting polymer with still increasing application potential in biomedicine. Its surface modification can be an efficient way how to introduce desired functional groups and to control its properties while keeping the bulk characteristics of the material unchanged. The purpose of the study was to synthetize thin films of pristine conducting polyaniline hydrochloride, non-conducting polyaniline base and polyaniline modified with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) and investigate chosen parameters of their hemocompatibility. The modification was performed either by introduction of PAMPSA during the synthesis or by reprotonation of polyaniline base. The polyaniline hydrochloride and polyaniline base had no impact on blood coagulation and platelet adhesion. By contrast, the polyaniline reprotonated with PAMPSA completely hindered coagulation thanks to its interaction with coagulation factors Xa, Va and IIa. The significantly lower platelets adhesion was also found on this surface. Moreover, this film maintains its conductivity at pH of 6, which is an improvement in comparison with standard polyaniline hydrochloride losing most of its conductivity at pH of 4. Polyaniline film with PAMPSA introduced during synthesis had an impact on platelet adhesion but not on coagulation. The combined conductivity, anticoagulation activity, low platelet adhesion and improved conductivity at pH closer to physiological, open up new possibilities for application of polyaniline reprotonated by PAMPSA in blood-contacting devices, such as catheters or blood vessel grafts. PMID:26119372

  18. Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity

    PubMed Central

    Kasess, Christian H.; Meyer, Bernhard M.; Hofmaier, Tina; Diers, Kersten; Bartova, Lucie; Pail, Gerald; Huf, Wolfgang; Uzelac, Zeljko; Hartinger, Beate; Kalcher, Klaudius; Perkmann, Thomas; Haslacher, Helmuth; Meyer-Lindenberg, Andreas; Kasper, Siegfried; Freissmuth, Michael; Windischberger, Christian; Willeit, Matthäus; Lanzenberger, Rupert; Esterbauer, Harald; Brocke, Burkhard; Moser, Ewald; Sitte, Harald H.; Pezawas, Lukas

    2014-01-01

    Background The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence. Methods A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet Vmax. Results The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity. Conclusion This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation. PMID:24667541

  19. Scalable evaluation of platelet aggregation by the degree of blood migration

    NASA Astrophysics Data System (ADS)

    Song, Suk-Heung; Lim, Chae-Seung; Shin, Sehyun

    2013-12-01

    Platelet aggregation plays a key role in vascular thrombosis. Antiplatelet drug therapy is commonly used for the prevention of abnormal platelet aggregation. So, measuring platelet aggregation function is critically important in clinical field. Here, we introduce a scalable evaluation method of platelet aggregation measured with the degree of blood migration through microchannel in a microfluidic chip. Unlike conventional methods that require expertise with system physics to operate devices, our approach is using microfluidics system, which requires only a syringe vacuum. The scalable migration factors, migration distance and touchdown time, are capable of distinguishing various antiplatelet drug effects under microfluidics and would be effective for the quick and easy evaluation of quantitative platelet aggregation.

  20. Function of human platelets during extracorporeal circulation.

    PubMed

    Hennessy, V L; Hicks, R E; Niewiarowski, S; Edmunds, L H; Colman, R W

    1977-06-01

    The interaction between human platelets and nonbiologic surfaces was studied during in vitro recirculation of 500 ml of fresh, heparinized human blood in four different perfusion circuits. Circuits differed in surface area (0.1 m2 or 0.9 m2) and in surface composition. No important differences were observed between standard silicone-rubber and filler-free, silicone-rubber surfaces. Platelet counts decreased to 85% of control in 0.1- m2 circuits, but retained normal sensitivity to aggregating agents and released only small amounts of platelet factor 4 (PF4). In contrast, platelet counts in 0.9-m2 circuits decreased to 20% of control within 2 min and platelet sensitivity was depressed out of proportion to the fall in platelet count. Plasma PF4 progressively increased and platelet PF4 content progressively decreased during 6 h of recirculation. The results indicate that human platelets may exist in three conditions during extracorporeal circulation. Some platelets are unaltered, some are less sensitive to aggregating agents, and others have undergone extensive release. The ratio of blood volume to surface area appears to be an important determinant of platelet-surface interaction. PMID:18017

  1. Micro-scale dynamic simulation of erythrocyte-platelet interaction in blood flow.

    PubMed

    AlMomani, T; Udaykumar, H S; Marshall, J S; Chandran, K B

    2008-06-01

    Platelet activation, adhesion, and aggregation on the blood vessel and implants result in the formation of mural thrombi. Platelet dynamics in blood flow is influenced by the far more numerous erythrocytes (RBCs). This is particularly the case in the smaller blood vessels (arterioles) and in constricted regions of blood flow (such as in valve leakage and hinge regions) where the dimensions of formed elements of blood become comparable with that of the flow geometry. In such regions, models to predict platelet motion, activation, aggregation and adhesion must account for platelet-RBC interactions. This paper studies platelet-RBC interactions in shear flows by performing simulations of micro-scale dynamics using a computational fluid dynamics (CFD) model. A level-set sharp-interface immersed boundary method is employed in the computations in which RBC and platelet boundaries are tracked on a two-dimensional Cartesian grid. The RBCs are assumed to have an elliptical shape and to deform elastically under fluid forces while the platelets are assumed to behave as rigid particles of circular shape. Forces and torques between colliding blood cells are modeled using an extension of the soft-sphere model for elliptical particles. RBCs and platelets are transported under the forces and torques induced by fluid flow and cell-cell and cell-platelet collisions. The simulations show that platelet migration toward the wall is enhanced with increasing hematocrit, in agreement with past experimental observations. This margination is seen to occur due to hydrodynamic forces rather than collisional forces or volumetric exclusion effects. The effect of fluid shear forces on the platelets increases exponentially as a function of hematocrit for the range of parameters covered in this study. The micro-scale analysis can be potentially employed to obtain a deterministic relationship between fluid forces and platelet activation and aggregation in blood flow past cardiovascular implants

  2. Role of platelet function and platelet membrane glycoproteins in children with primary immune thrombocytopenia

    PubMed Central

    Liu, Wen-Jun; Bai, Jing; Guo, Qu-Lian; Huang, Zhe; Yang, Hong; Bai, Yong-Qi

    2016-01-01

    The aim of the present study was to examine and understand changes in platelet functions prior to and after the treatment of primary immune thrombocytopenia (ITP) in children. An automatic hematology analyzer and whole blood flow cytometry were used to detect immature platelet fraction (IPF), IPC and membrane glycoproteins (CD62p, PAC-1 and CD42b) in ITP children (ITP group), children with complete response after ITP treatment (ITP-CR group) and children with elective surgery (normal control group). The results showed that, levels of platelet count (PLT) and plateletcrit in the ITP group were lower alhtough the levels of mean platelet volume, platelet distribution width and platelet-large cell ratio (P-LCR) were higher than those in the normal control and ITP-CR groups. PLT in the ITP-CR group was lower than that in the normal controls. Additionally, IPF% was higher in the normal control and ITP-CR groups, IPC was lower in the ITP group compared to the normal control and ITP-CR groups. Furthermore, prior to ADP activation, the expression levels of CD62p, PAC-1 and CD42b in the ITP group were lower in ITP group than those in the normal control and ITP-CR groups. The expression level of PAC-1 was lower in the ITP-CR and normal control groups. No differences were identified in CD62p and CD42b expression levels. Following ATP activation, CD62p, PAC-1 and CD42b expression in the ITP group was lower than that in the normal control and ITP-CR groups. PAC-1 expression was lower while CD62p expression was higher in the ITP-CR group compared to the normal control group. In conclusion, the activation of platelets in ITP children was low. Decreased platelet function, platelet parameters and platelet glycoproteins may be used as markers for monitoring the treatment efficacy in ITP children. PMID:27431926

  3. Three-dimensional multi-scale model of deformable platelets adhesion to vessel wall in blood flow.

    PubMed

    Wu, Ziheng; Xu, Zhiliang; Kim, Oleg; Alber, Mark

    2014-08-01

    When a blood vessel ruptures or gets inflamed, the human body responds by rapidly forming a clot to restrict the loss of blood. Platelets aggregation at the injury site of the blood vessel occurring via platelet-platelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. A novel three-dimensional multi-scale model is introduced and used in this paper to simulate receptor-mediated adhesion of deformable platelets at the site of vascular injury under different shear rates of blood flow. The novelty of the model is based on a new approach of coupling submodels at three biological scales crucial for the early clot formation: novel hybrid cell membrane submodel to represent physiological elastic properties of a platelet, stochastic receptor-ligand binding submodel to describe cell adhesion kinetics and lattice Boltzmann submodel for simulating blood flow. The model implementation on the GPU cluster significantly improved simulation performance. Predictive model simulations revealed that platelet deformation, interactions between platelets in the vicinity of the vessel wall as well as the number of functional GPIbα platelet receptors played significant roles in platelet adhesion to the injury site. Variation of the number of functional GPIbα platelet receptors as well as changes of platelet stiffness can represent effects of specific drugs reducing or enhancing platelet activity. Therefore, predictive simulations can improve the search for new drug targets and help to make treatment of thrombosis patient-specific. PMID:24982253

  4. A Mathematical Model and Numerical Method for Studying Platelet Adhesion and Aggregation during Blood Clotting

    NASA Astrophysics Data System (ADS)

    Fogelson, Aaron L.

    1984-10-01

    The repair of small blood vessels and the pathological growth of internal blood clots involve the formation of platelet aggregates adhering to portions of the vessel wall. Our microscopic model represents blood by a suspension of discrete massless platelets in a viscous incompressible fluid. Platelets are initially noncohesive; however, if stimulated by an above-threshold concentration of the chemical ADP or by contact with the adhesive injured region of the vessel wall, they become cohesive and secrete more ADP into the fluid. Cohesion between platelets and adhesion of a platelet to the injured wall are modeled by creating elastic links. Repulsive forces prevent a platelet from coming too close to another platelet or to the wall. The forces affect the fluid motion in the neighborhood of an aggregate. The platelets and secreted ADP both move by fluid advection and diffusion. The equations of the model are studied numerically in two dimensions. The platelet forces are calculated implicitly by minimizing a nonlinear energy function. Our minimization scheme merges Gill and Murray's ( Math. Programming7 (1974) , 311) modified Newton's method with elements of the Yale sparse matrix package. The stream-function' formulation' of the Stokes' equations for the fluid motion under the influence of platelet forces is solved using Bjorstad's biharmonic solver ("Numerical Solution of the Biharmonic Equation," Ph. D. Thesis, Stanford University, 1980). The ADP transport equation is solved with an alternating-direction implicit scheme. A linked-list data structure is introduced to keep track of changing platelet states and changing configurations of interplatelet links. Results of calculations with healthy platelets and with diseased platelets are presented.

  5. Point-of-care platelet function tests: detection of platelet inhibition induced by nonopioid analgesic drugs.

    PubMed

    Scharbert, Gisela; Gebhardt, Kristina; Sow, Zacharia; Duris, Monika; Deusch, Engelbert; Kozek-Langenecker, Sibylle

    2007-12-01

    Detection of platelet inhibition is of clinical relevance in the preinterventional risk-benefit assessment in chronic low-back-pain patients scheduled for invasive pain therapy. We evaluated the sensitivity of various point-of-care platelet function tests for the detection of platelet inhibition induced by nonopioid analgesic drugs. After Institutional Review Board approval and informed consent, citrated whole blood from 40 patients with chronic unspecific low back pain was investigated before and 30 min after intravenous infusion of the study medication consisting of diclofenac 75 mg (plus orphenadrin 30 mg; Neodolpasse; Fresenius Kabi Austria GmbH, Austria), parecoxib 40 mg (Dynastat; Pharmacia Europe EEIG, UK), paracetamol 1 g (Perfalgan; Bieffe Medital S.P.A., Italy), or normal saline in a randomized, cross-over, double-blinded, placebo-controlled study. Platelet function was assessed using the PFA-100 platelet function analyzer and thromboelastometry, as well as impedance aggregometry (in the last 17 patients recruited after it became commercially available). Sensitivity for detecting diclofenac-induced platelet inhibition was 85% for the PFA-100 using epinephrine as agonist and 94% for arachidonic acid-induced impedance aggregometry. ADP-induced platelet function tests, as well as cytochalasin D-modified thromboelastometry were unreliable. All tests had a low incidence of false-positive test results after normal saline. Paracetamol and parecoxib had no significant platelet inhibiting effect. The PFA-100 using epinephrine as agonist and arachidonic acid-induced impedance aggregometry are recommended for the detection of cyclooxygenase-I-inhibiting effects of nonsteroidal anti-inflammatory drugs such as diclofenac. Our findings confirm that a single rescue dose of paracetamol and parecoxib has no antiplatelet effect. PMID:17982319

  6. [Improvement in cryopreservation of blood platelets].

    PubMed

    Zhiburt, E B; Vil'ianinov, V N; Kaleko, S P; Sidorkevich, S V; Petrenko, G I; Bagautdinov, Sh M; Kuz'min, N S

    2000-01-01

    The first Russian solution Krimolit designed for cryopreservation of platelet concentrates down -196 degrees C was clinically tested. The therapeutical efficacy of the cryopreserved platelets was evaluated on the basis of clinical and laboratory monitoring of transfusions in 20 cancer hematological patients. They were found to have the same therapeutical action as fresh cells. The introduction of cryopreserved platelets into clinical practice allows one to form stores and to transfuse autological cells. Krimolit is recommended for clinical application. PMID:10740789

  7. Effects of microgravity and hypergravity on platelet functions.

    PubMed

    Dai, Kesheng; Wang, Yuedan; Yan, Rong; Shi, Quanwei; Wang, Zhicheng; Yuan, Yanhong; Cheng, Hong; Li, Suping; Fan, Yubo; Zhuang, Fengyuan

    2009-05-01

    Many serious thrombotic and haemorrhagic diseases or fatalities have been documented in human being exposed to microgravity or hypergravity environments, such as crewmen in space, roller coaster riders, and aircrew subjected to high-G training. Some possible related organs have been examined to explore the mechanisms underlying these gravity change-related diseases. However, the role of platelets which are the primary players in both thrombosis and haemostasis is unknown. Here we show that platelet aggregation induced by ristocetin or collagen and platelet adhesion to von Willebrand factor (VWF) were significantly decreased after platelets were exposed to simulated microgravity. Conversely, these platelet functions were increased after platelets were exposed to hypergravity. The tail bleeding time in vivo was significantly shortened in mice exposed to high-G force, whereas, was prolonged in hindlimb unloaded mice. Furthermore, three of 23 mice died after 15 minutes of -8 Gx stress. Platelet thrombi disseminated in the heart ventricle and blood vessels in the brain, lung, and heart from the dead mice. Finally, glycoprotein (GP) Ibalpha surface expression and its association with the cytoskeleton were significantly decreased in platelets exposed to simulated microgravity, and obviously increased in hypergravity-exposed platelets. These data indicate that the platelet functions are inhibited in microgravity environments, and activated under high-G conditions, suggesting a novel mechanism for gravity change-related haemorrhagic and thrombotic diseases. This mechanism has important implications for preventing and treating gravity change-related diseases, and also suggests that special attentions should be paid to human actions under different gravity conditions. PMID:19404544

  8. P2 receptors and platelet function.

    PubMed

    Hechler, Béatrice; Gachet, Christian

    2011-09-01

    Following vessel wall injury, platelets adhere to the exposed subendothelium, become activated and release mediators such as TXA(2) and nucleotides stored at very high concentration in the so-called dense granules. Released nucleotides and other soluble agents act in a positive feedback mechanism to cause further platelet activation and amplify platelet responses induced by agents such as thrombin or collagen. Adenine nucleotides act on platelets through three distinct P2 receptors: two are G protein-coupled ADP receptors, namely the P2Y(1) and P2Y(12) receptor subtypes, while the P2X(1) receptor ligand-gated cation channel is activated by ATP. The P2Y(1) receptor initiates platelet aggregation but is not sufficient for a full platelet aggregation in response to ADP, while the P2Y(12) receptor is responsible for completion of the aggregation to ADP. The latter receptor, the molecular target of the antithrombotic drugs clopidogrel, prasugrel and ticagrelor, is responsible for most of the potentiating effects of ADP when platelets are stimulated by agents such as thrombin, collagen or immune complexes. The P2X(1) receptor is involved in platelet shape change and in activation by collagen under shear conditions. Each of these receptors is coupled to specific signal transduction pathways in response to ADP or ATP and is differentially involved in all the sequential events involved in platelet function and haemostasis. As such, they represent potential targets for antithrombotic drugs. PMID:21792575

  9. ABO blood group as a model for platelet glycan modification in arterial thrombosis

    PubMed Central

    Zhong, Ming; Zhang, Hanrui; Reilly, John P.; Chrisitie, Jason D.; Ishihara, Mayumi; Kumagai, Tadahiro; Azadi, Parastoo; Reilly, Muredach P.

    2015-01-01

    ABO blood groups have long been associated with cardiovascular disease, thrombosis and acute coronary syndromes. Many studies over the years have shown type O blood group to be associated with lower risk of cardiovascular disease compared to non-type O blood groups. However, the mechanisms underlying this association remain unclear. Although ABO blood group is associated with variations in concentrations of circulating von Willebrand Factor and other endothelial cell adhesion molecules, ABO antigens are also present on several platelet surface glycoproteins and glycosphingolipids. As we highlight in this platelet-centric review, these glycomic modifications may impact platelet function in arterial thrombosis. More broadly, improving our understanding of the role of platelet glycan modifications in acute coronary syndromes may inform future diagnostics and therapeutics for cardiovascular diseases. PMID:26044584

  10. A computer planning model for blood platelet production and distribution.

    PubMed

    Sirelson, V; Brodheim, E

    1991-08-01

    We consider a class of policies for stocking hospital blood banks with units of random donor platelet concentrate ('Platelets') based upon scheduled daily deliveries from a regional blood center to replenish the platelet inventory to a fixed 'base stock' level. The measures of interest are the 'shortage rate' (the proportion of days for which the on-hand inventory at the hospital blood bank is insufficient to meet the demand) and the 'outdate rate' (the proportion of total units shipped which are not transfused within the usable life span of 5 days). Our principal results give a predictive model which relates the base stock level to the shortage rate and outdate rate. Our model uses only the mean daily demand as a parameter. It provides a basis to unify the results from other studies which have demonstrated improvements in platelet inventory management in particular hospitals and blood centers. PMID:1752123

  11. Mathematical model and numerical method for studying platelet adhesion and aggregation during blood clotting

    SciTech Connect

    Fogelson, A.L.

    1984-10-01

    The repair of small blood vessels and the pathological growth of internal blood clots involve the formation of platelet aggregates adhering to portions of the vessel wall. Our microscopic model represents blood by a suspension of discrete massless platelets in a viscous incompressible fluid. Platelets are initially noncohesive; however, if stimulated by an above-threshold concentration of the chemical ADP or by contact with the adhesive injured region of the vessel wall, they become cohesive and secrete more ADP into the fluid. Cohesion between platelets and adhesion of a platelet to the injured wall are modeled by creating elastic links. Repulsive forces prevent a platelet from coming too close to another platelet or to the wall. The forces affect the fluid motion in the neighborhood of an aggregate. The platelets and secreted ADP both move by fluid advection and diffusion. The equations of the model are studied numerically in two dimensions. The platelet forces are calculated implicitly by minimizing a nonlinear energy function. Our minimization scheme merges Gill and Murray's (Math. Programming 7 (1974), 311) modified Newton's method with elements of the Yale sparse matix package. The stream-function formulation of the Stokes' equations for the fluid motion under the influence of platelet forces is solved using Bjorstad's biharmonic solver (''Numerical Solution of the Biharmonic Equation,'' Ph.D. Thesis, Stanford University, 1980). The ADP transport equation is solved with an alternating-direction implicit scheme. A linked-list data structure is introduced to keep track of changing platelet states and changing configurations of interplatelet links.

  12. Which is the best anticoagulant for whole blood aggregometry platelet function testing? Comparison of six anticoagulants and diverse storage conditions.

    PubMed

    Kaiser, Andreas Friedrich Christoph; Neubauer, Horst; Franken, Cora Christina; Krüger, Jan-Christoph; Mügge, Andreas; Meves, Saskia Hannah

    2012-01-01

    Major hindrances of impedance aggregometry are caused by limited storage time and the requirement of ex vivo anticoagulation. Data on the influence of different anticoagulants and storage conditions are rare and incomplete. This study has systematically examined the influence of six different anticoagulants (sodium and lithium heparin, 20 µg/mL and 45 µg/mL r-hirudin, benzylsulfonyl-D-Arg-Pro-4-amidinobenzylamide (BAPA), and citrate) on the results of Adenosine 5'-diphosphate (ADP) and arachidonic acid (AA) induced measurements using multiple-electrode impedance aggregometer (MEA). Measurements were carried out in a time frame of 0 min up to 48 h after blood withdrawal. In addition, the influence of storage temperatures of 4°C and 37°C was evaluated. Results of ADP-induced tests significantly varied within the first 30 min in all tested anticoagulants, in citrated blood even within the first 60 min. They remained stable up to 2 h in 20 µg/mL r-hirudin and BAPA, 4 h in citrate, 8 h in 45 µg/mL r-hirudin, and lithium heparin and up to a maximum of 12 h in sodium heparin anticoagulated blood. The analysis of AA-induced tests revealed no significantly different results up to 6 h when BAPA was used, 8 h in lithium heparin, 20 µg/mL r-hirudin and citrate, 12 h in 45 µg/mL r-hirudin, and even 24 h in sodium heparin-anticoagulated samples. A storage temperature of either 4°C or 37°C in contrast to room temperature had a negative influence on the stability of results. In conclusion, sodium heparin and 45 µg/mL r-hirudin as anticoagulants guarantee the longest storage time for impedance aggregometry. PMID:21999185

  13. Topographic Cues Reveal Two Distinct Spreading Mechanisms in Blood Platelets

    PubMed Central

    Sandmann, Rabea; Köster, Sarah

    2016-01-01

    Blood platelets are instrumental in blood clotting and are thus heavily involved in early wound closure. After adhering to a substrate they spread by forming protrusions like lamellipodia and filopodia. However, the interaction of these protrusions with the physical environment of platelets while spreading is not fully understood. Here we dynamically image platelets during this spreading process and compare their behavior on smooth and on structured substrates. In particular we analyze the temporal evolution of the spread area, the cell morphology and the dynamics of individual filopodia. Interestingly, the topographic cues enable us to distinguish two spreading mechanisms, one that is based on numerous persistent filopodia and one that rather involves lamellipodia. Filopodia-driven spreading coincides with a strong response of platelet morphology to the substrate topography during spreading, whereas lamellipodia-driven spreading does not. Thus, we quantify different degrees of filopodia formation in platelets and the influence of filopodia in spreading on structured substrates. PMID:26934830

  14. Topographic Cues Reveal Two Distinct Spreading Mechanisms in Blood Platelets

    NASA Astrophysics Data System (ADS)

    Sandmann, Rabea; Köster, Sarah

    2016-03-01

    Blood platelets are instrumental in blood clotting and are thus heavily involved in early wound closure. After adhering to a substrate they spread by forming protrusions like lamellipodia and filopodia. However, the interaction of these protrusions with the physical environment of platelets while spreading is not fully understood. Here we dynamically image platelets during this spreading process and compare their behavior on smooth and on structured substrates. In particular we analyze the temporal evolution of the spread area, the cell morphology and the dynamics of individual filopodia. Interestingly, the topographic cues enable us to distinguish two spreading mechanisms, one that is based on numerous persistent filopodia and one that rather involves lamellipodia. Filopodia-driven spreading coincides with a strong response of platelet morphology to the substrate topography during spreading, whereas lamellipodia-driven spreading does not. Thus, we quantify different degrees of filopodia formation in platelets and the influence of filopodia in spreading on structured substrates.

  15. Platelets mediate lymphovenous hemostasis to maintain blood-lymphatic separation throughout life.

    PubMed

    Hess, Paul R; Rawnsley, David R; Jakus, Zoltán; Yang, Yiqing; Sweet, Daniel T; Fu, Jianxin; Herzog, Brett; Lu, MinMin; Nieswandt, Bernhard; Oliver, Guillermo; Makinen, Taija; Xia, Lijun; Kahn, Mark L

    2014-01-01

    Mammals transport blood through a high-pressure, closed vascular network and lymph through a low-pressure, open vascular network. These vascular networks connect at the lymphovenous (LV) junction, where lymph drains into blood and an LV valve (LVV) prevents backflow of blood into lymphatic vessels. Here we describe an essential role for platelets in preventing blood from entering the lymphatic system at the LV junction. Loss of CLEC2, a receptor that activates platelets in response to lymphatic endothelial cells, resulted in backfilling of the lymphatic network with blood from the thoracic duct (TD) in both neonatal and mature mice. Fibrin-containing platelet thrombi were observed at the LVV and in the terminal TD in wild-type mice, but not Clec2-deficient mice. Analysis of mice lacking LVVs or lymphatic valves revealed that platelet-mediated thrombus formation limits LV backflow under conditions of impaired valve function. Examination of mice lacking integrin-mediated platelet aggregation indicated that platelet aggregation stabilizes thrombi that form in the lymphatic vascular environment to prevent retrograde blood flow. Collectively, these studies unveil a newly recognized form of hemostasis that functions with the LVV to safeguard the lymphatic vascular network throughout life. PMID:24292710

  16. Platelet functional and transcriptional changes induced by intralipid infusion.

    PubMed

    Beaulieu, Lea M; Vitseva, Olga; Tanriverdi, Kahraman; Kucukural, Alper; Mick, Eric; Hamburg, Naomi; Vita, Joseph; Freedman, Jane E

    2016-06-01

    Multiple studies have shown the effects of long-term exposure to high-fat or western diets on the vascular system. There is limited knowledge on the acute effects of high circulating fat levels, specifically on platelets, which have a role in many processes, including thrombosis and inflammation. This study investigated the effects of acute, high-fat exposure on platelet function and transcript profile. Twenty healthy participants were given an intravenous infusion of 20% Intralipid emulsion and heparin over 6 hours. Blood samples were taken prior to and the day after infusion to measure platelet function and transcript expression levels. Platelet aggregation was not significantly affected by Intralipid infusion, but, when mitochondria function was inhibited by carbonyl cyanide 3-chlorophenylhydrazone (CCCP) or oligomycin, platelet aggregation was higher in the post-infusion state compared to baseline. Through RNA sequencing, and verified by RT-qPCR, 902 miRNAs and 617 mRNAs were affected by Intralipid infusion. MicroRNAs increased include miR-4259 and miR-346, while miR-517b and miR-517c are both decreased. Pathway analysis identified two clusters significantly enriched, including cell motility. In conclusion, acute exposure to high fat affects mitochondrial-dependent platelet function, as well as the transcript profile. PMID:26940969

  17. Sodium-hydrogen exchange and platelet function.

    PubMed

    Rosskopf, D

    1999-07-01

    On stimulation of platelets with agonists, for example, thrombin, a rapid rise in intracellular pH is observed. This alkalinization is mediated by an increase in transport activity of the Na(+)/H(+) exchanger isoform NHE1. In addition to this Na(+)/H(+) exchange mechanism, platelets express bicarbonate/chloride exchangers, which also contribute to pH(i) homeostasis. The main functions of NHE1 in platelets include pH(i) control, volume regulation, and participation in cell signaling. The isoform NHE1 is highly sensitive toward inhibition by EIPA, Hoe694, and Hoe642. The regulation of NHE1 activity is complex and is not completely understood. It includes the MAP kinase cascade, the Ca/calmodulin system, several heterotrimeric G proteins (Galpha12, Galpha13, Galphaq, and Galphai), small G proteins (ras, cdc42, rhoA), and downstream kinases (e.g., p160ROCK). Volume challenges stimulate tyrosine phosphorylation of cytoplasmic proteins, which ultimately activate NHE1. Thrombin, thromboxane, platelet-activating factor, angiotensin II, endothelin, phorbol ester, and Ca(2+) ionophors stimulate NHE1 activity in platelets. Blockade of platelet NHE1 can inhibit platelet activation. With the development of highly specific NHE1 inhibitors, detailed investigation of the relationships between NHE1 activity and platelet activation now becomes feasible. PMID:10481210

  18. Detection and effects on platelet function of anti-platelet antibody in mule foals with experimentally induced neonatal alloimmune thrombocytopenia.

    PubMed

    Ramirez, S; Gaunt, S D; McClure, J J; Oliver, J

    1999-01-01

    Horse mares carrying mule foals were immunized during the last trimester of pregnancy with whole acid-citrate-dextrose-anticoagulated donkey blood to experimentally induce neonatal alloimmune thrombocytopenia. Thrombocytopenia occurred in the neonatal mule foals born to immunized horse mares within 24 hours after ingestion of their dams' colostrum. Mule foals born to mares not immunized with donkey blood did not develop thrombocytopenia. These findings suggest that antibodies may have been directed against a donkey platelet antigen present in the mule foals but not present in their dams. The objectives of this study were to determine whether anti-platelet antibody could be detected in mule foals with experimentally induced neonatal alloimmune thrombocytopenia, to identify any platelet proteins recognized by serum antibody in these foals, and to determine if platelet function was altered by sera from these mule foals. An indirect enzyme-linked immunosorbent assay demonstrated significantly higher absorption at 1:200 of platelet-bindable immunoglobulin G in serum from thrombocytopenic mule foals, compared with nonthrombocytopenic mule foals. Sera from thrombocytopenic and nonthrombocytopenic mule foals produced similar binding patterns in western immunoblots with donkey platelet proteins separated on sodium dodecyl sulfate polyacrylamide gels. Maximal platelet aggregation and relative slope of aggregation in response to collagen were significantly inhibited after incubation with sera from thrombocytopenic mule foals. These results suggest that mule foals with induced alloimmune thrombocytopenia have serum antibodies that bind to platelets and may compete with collagen binding sites to impair platelet aggregation. PMID:10587252

  19. Inherited Platelet Function Disorders: Algorithms for Phenotypic and Genetic Investigation.

    PubMed

    Gresele, Paolo; Bury, Loredana; Falcinelli, Emanuela

    2016-04-01

    Inherited platelet function disorders (IPFDs) manifest with mucocutaneous bleeding and are frequently difficult to diagnose due to their heterogeneity, the complexity of the platelet activation pathways and a lack of standardization of the platelet function laboratory assays and of their use for this purpose. A rational diagnostic approach to IPFDs should follow an algorithm where clinical examination and a stepwise laboratory evaluation play a crucial role. A streamlined panel of laboratory tests, with consecutive steps of increasing level of complexity, allows the phenotypic characterization of most IPFDs. A first-line diagnosis of a significant fraction of the IPFD may be made also at nonspecialized centers by using relatively simple tests, including platelet count, peripheral blood smear, light transmission aggregometry, measurement of platelet granule content and release, and the expression of glycoproteins by flow cytometry. Some of the most complex, second- and third-step tests may be performed only in highly specialized laboratories. Genotyping, including the widespread application of next-generation sequencing, has enabled discovery in the last few years of several novel genes associated with platelet disorders and this method may eventually become a first-line diagnostic approach; however, a preliminary clinical and laboratory phenotypic characterization nowadays still remains crucial for diagnosis of IPFDs. PMID:26962877

  20. Influence of gold nanoparticles on platelets functional activity in vitro

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Akchurin, George G.; Ivanov, Alexey N.; Kirichuk, Vyacheslav F.; Terentyuk, George S.; Khlebtsov, Boris N.; Khlebtsov, Nikolay G.

    2008-02-01

    Now in the leading biomedical centers of the world approved new technology of laser photothermal destruction of cancer cells using plasmon gold nanoparticles. Investigations of influence of gold nanoparticles on white rat platelets aggregative activity in vitro have been made. Platelet aggregation was investigated in platelet rich plasma (PRP) with help of laser analyzer 230 LA <>, Russia). Aggregation inductor was ADP solution in terminal concentration 2.5 micromole (<>, Russia). Gold nanoshells soluted in salt solution were used for experiments. Samples of PRP were incubated with 50 or 100 μl gold nanoshells solution in 5 minute, after that we made definition ADP induced platelet aggregation. We found out increase platelet function activity after incubation with nanoparticles solution which shown in maximum ADP-induced aggregation degree increase. Increase platelet function activity during intravenous nanoshells injection can be cause of thrombosis on patients. That's why before clinical application of cancer cell destruction based on laser photothermal used with plasmon gold nanoparticles careful investigations of thrombosis process and detail analyze of physiological blood parameters are very necessary.

  1. Circulating and platelet-derived microparticles in human blood enhance thrombosis on atherosclerotic plaques.

    PubMed

    Suades, Rosa; Padró, Teresa; Vilahur, Gemma; Badimon, Lina

    2012-12-01

    Plaque rupture followed by thrombosis is the underlying cause of the majority of acute coronary syndromes. Circulating microparticles (cMPs), membrane blebs released into blood by activated cells, have been associated to vascular diseases. Specifically, high levels of platelet-derived microparticles (pMPs) have been found in patients with coronary disease. However, it is unknown whether microparticles have a contributing role to the development of damaged vessel wall-induced arterial thrombi. The aim of this proof of concept study was to investigate whether an increased number of cMPs and pMPs could functionally contribute to blood thrombogenicity on areas of arterial damage. Microparticles were isolated from blood of healthy volunteers and were characterised by flow cytometry. Effects of microparticles on platelet deposition were assessed under controlled flow conditions exposing damaged arterial wall in the Badimon perfusion chamber and collagen type-I in the flat perfusion chamber to human blood. Platelet deposition on damaged arteries was significantly increased in cMP- and pMP-enriched bloods (p<0.05). pMPs also induced increase in platelet (p<0.05) and fibrin (p<0.05) deposition on human atherosclerotic arteries and in platelet adhesion to purified collagen surfaces. pMP-enriched blood induced a dose-dependent shortening of epinephrine/collagen closure time evaluated by PFA-100 (p<0.001), increased low-dose ADP-induced platelet aggregation by LTA (p<0.05), and decreased clotting time by thromboelastography (p<0.01). In conclusion, an increased content of cMPs and pMPs, even in normal blood conditions, enhance platelet deposition and thrombus formation. This study shows for the first time that, beyond biomarkers of cell activation, blood microparticles have functional effects on cardiovascular atherothrombotic disease. PMID:23138460

  2. Viability and functional integrity of washed platelets.

    PubMed

    Pineda, A A; Zylstra, V W; Clare, D E; Dewanjee, M K; Forstrom, L A

    1989-01-01

    The viability and functional integrity of saline- and ACD-saline-washed platelets were compared with those of unwashed platelets. After template bleeding time (TBT) was measured, 15 healthy volunteers underwent plateletpheresis and ingested 600 mg of aspirin. Autologous 111In-labeled platelets were transfused: unwashed (n = 5), washed with 0.9 percent saline solution (SS) (n = 5), and washed with a buffered 12.6 percent solution of ACD-A in 0.9 percent saline solution (n = 5). After transfusion, we measured TBT at 1, 4, and 24 hours; platelet survival at 10 minutes and 1, 4, and 24 hours and daily for 6 days; and the percentage of uptake in liver and spleen by quantitative whole-body radionuclide scintigraphy at 24 and 190 hours. We found that saline washing affected platelet recovery, 23.47 +/- 12 percent (p less than 0.001) as compared to 52.43 +/- 17 percent (p less than 0.002) for ACD-saline and 73.17 +/- 8 percent for control; that saline washing resulted in a greater liver uptake than control and ACD-saline-washed platelets (31.9 +/- 8% [p less than 0.001] vs 17.7 +/- 4.1 and 19.3 +/- 2.1% [p greater than 0.1], respectively); that, unlike control and ACD-saline-washed platelets, saline-washed platelets did not shorten bleeding time; and that neither type of washing affected survival. Although ACD-saline washing affects recovery, it also results in intact function, normal survival, higher recovery than SS platelets, and no significant liver uptake. PMID:2749876

  3. Viability and functional integrity of washed platelets

    SciTech Connect

    Pineda, A.A.; Zylstra, V.W.; Clare, D.E.; Dewanjee, M.K.; Forstrom, L.A.

    1989-07-01

    The viability and functional integrity of saline- and ACD-saline-washed platelets were compared with those of unwashed platelets. After template bleeding time (TBT) was measured, 15 healthy volunteers underwent plateletpheresis and ingested 600 mg of aspirin. Autologous /sup 111/In-labeled platelets were transfused: unwashed (n = 5), washed with 0.9 percent saline solution (SS) (n = 5), and washed with a buffered 12.6 percent solution of ACD-A in 0.9 percent saline solution (n = 5). After transfusion, we measured TBT at 1, 4, and 24 hours; platelet survival at 10 minutes and 1, 4, and 24 hours and daily for 6 days; and the percentage of uptake in liver and spleen by quantitative whole-body radionuclide scintigraphy at 24 and 190 hours. We found that saline washing affected platelet recovery, 23.47 +/- 12 percent (p less than 0.001) as compared to 52.43 +/- 17 percent (p less than 0.002) for ACD-saline and 73.17 +/- 8 percent for control; that saline washing resulted in a greater liver uptake than control and ACD-saline-washed platelets (31.9 +/- 8% (p less than 0.001) vs 17.7 +/- 4.1 and 19.3 +/- 2.1% (p greater than 0.1), respectively); that, unlike control and ACD-saline-washed platelets, saline-washed platelets did not shorten bleeding time; and that neither type of washing affected survival. Although ACD-saline washing affects recovery, it also results in intact function, normal survival, higher recovery than SS platelets, and no significant liver uptake.

  4. Role of platelet function and platelet membrane glycoproteins in children with primary immune thrombocytopenia.

    PubMed

    Liu, Wen-Jun; Bai, Jing; Guo, Qu-Lian; Huang, Zhe; Yang, Hong; Bai, Yong-Qi

    2016-09-01

    The aim of the present study was to examine and understand changes in platelet functions prior to and after the treatment of primary immune thrombocytopenia (ITP) in children. An automatic hematology analyzer and whole blood flow cytometry were used to detect immature platelet fraction (IPF), IPC and membrane glycoproteins (CD62p, PAC-1 and CD42b) in ITP children (ITP group), children with complete response after ITP treatment (ITP-CR group) and children with elective surgery (normal control group). The results showed that, levels of platelet count (PLT) and plateletcrit in the ITP group were lower alhtough the levels of mean platelet volume, platelet distribution width and platelet-large cell ratio (P-LCR) were higher than those in the normal control and ITP-CR groups. PLT in the ITP-CR group was lower than that in the normal controls. Additionally, IPF% was higher in the normal control and ITP-CR groups, IPC was lower in the ITP group compared to the normal control and ITP-CR groups. Furthermore, prior to ADP activation, the expression levels of CD62p, PAC-1 and CD42b in the ITP group were lower in ITP group than those in the normal control and ITP-CR groups. The expression level of PAC-1 was lower in the ITP-CR and normal control groups. No differences were identified in CD62p and CD42b expression levels. Following ATP activation, CD62p, PAC-1 and CD42b expression in the ITP group was lower than that in the normal control and ITP-CR groups. PAC-1 expression was lower while CD62p expression was higher in the ITP-CR group compared to the normal control group. In conclusion, the activation of platelets in ITP children was low. Decreased platelet function, platelet parameters and platelet glycoproteins may be used as markers for monitoring the treatment efficacy in ITP children. PMID:27431926

  5. Evaluation of a BED-SIDE platelet function assay: performance and clinical utility.

    PubMed

    Lau, Wei C; Walker, C Ty; Obilby, David; Wash, Mark M; Carville, David G M; Guyer, Kirk E; Bates, Eric R

    2002-01-01

    Platelets have a pivotal role in the initial defense against insult to the vasculature and are also recognized of critical importance in the acute care settings of percutaneous coronary intervention and cardiopulmonary bypass. In these environments both platelet count and function may be markedly compromised. Unfortunately, current assays to evaluate the parameters of platelet count and function are of limited utility for bed-side testing. Moreover, it is suggested that there may be significant inter patient variation in response to antiplatelet therapy that may be exacerbated by other agents (e.g. heparin) that are routinely administered during cardiac intervention. Here we describe a practical, rapid and user-friendly whole blood platelet function assay that has been developed for use in bed-side settings. Platelet agonists were formulated with an anticoagulant and lyophilized in blood collection tubes standardised to receive a l mL fresh whole blood sample. In the presence of an agonist, platelets are activated and interact (aggregate). Using traditional cell counting principles, non-aggregated platelets are counted whereas aggregated platelets are not. The percentage (%) of functional platelets in reference to a baseline tube may then be determined. Results are available within four minutes. Platelet aggregation in whole blood demonstrated good correlation with turbidometric aggregometry for both ADP (r=0.91) and collagen (r=0.88). Moreover, in clinical settings where antiplatelet agents were administered, this rapid, bed-side, platelet function assay demonstrated utility in monitoring patient response to these therapies. This novel bed-side assay of platelet function is extremely suitable for the clinical environment with a rapid turn-around time. In addition, it provides a full haematology profile, including platelet count, and should permit enhancement of transfusion and interventional decisions. PMID:17890800

  6. Serotonin Uptake Is Largely Mediated by Platelets versus Lymphocytes in Peripheral Blood Cells

    PubMed Central

    2012-01-01

    The serotonin transporter (SERT), a primary target for many antidepressants, is expressed in the brain and also in peripheral blood cells. Although platelet SERT function is well accepted, lymphocyte SERT function has not been definitively characterized. Due to their small size, platelets often are found in peripheral blood mononuclear cell preparations aimed at isolating lymphocytes, monocytes, and macrophages. The presence of different cells makes it difficult to assign SERT expression and function to specific cell types. Here, we use flow cytometry and IDT307, a monoamine transporter substrate that fluoresces after uptake into cells, to investigate SERT function in lymphocyte and platelet populations independently, as well as simultaneously without prior isolation. We find that murine lymphocytes exhibit temperature-dependent IDT307 transport but uptake is independent of SERT. Lack of measurable SERT function in lymphocytes was corroborated by chronoamperometry using serotonin as a substrate. When we examined rhesus and human mixed blood cell populations, we found that platelets, and not lymphocytes, were primary contributors to SERT function. Overall, these findings indicate that lymphocyte SERT function is minimal. Moreover, flow cytometry, in conjunction with the fluorescent transporter substrate IDT307, can be widely applied to investigate SERT in platelets from populations of clinical significance. PMID:23336055

  7. STIM and Orai in platelet function.

    PubMed

    Varga-Szabo, David; Braun, Attila; Nieswandt, Bernhard

    2011-09-01

    Physiological platelet activation and thrombus formation are essential to stop bleeding in case of vascular injury, whereas inadequate triggering of the same process in diseased vessels can lead to fatal thromboembolism and tissue ischemia of vital organs. A central step in platelet activation is agonist-induced elevation of the intracellular Ca(2+) concentration. This happens on the one hand through the release of Ca(2+) from intracellular stores and on the other hand through Ca(2+) influx from the extracellular space. In platelets, the major Ca(2+) influx pathway is the so-called store operated Ca(2+) entry (SOCE), induced by store depletion. Studies in the last five years discovered the molecular background of platelet SOCE. Stromal interaction molecule 1 (STIM1) and Orai1, two so far unknown molecules, got in the focus of research. STIM1 was found to be the Ca(2+) sensor in the endoplasmic reticulum (ER) membrane, whereas Orai1 was identified as the major store operated Ca(2+) (SOC) channel in the plasma membrane. These two molecules and their role in platelet function and thrombus formation are the topic of the present review with a special focus on apoptosis and apoptosis-like processes in platelet physiology. PMID:21616531

  8. Simulation of the Effect of Red Blood Cell Collisions on Platelet Adsorption

    NASA Astrophysics Data System (ADS)

    Fitzgibbon, Sean; Zhao, Hong; Shaqfeh, Eric

    2012-11-01

    The adsorption of platelets to the endothelial wall is an important first step in the clotting process, which is critical to stopping blood loss after trauma. Initial platelet arrest is controlled by very short range interaction between two proteins, von Willibrand Factor and GPIb, so the rate of platelet adsorption is expected to be strongly dependent on the rate at which the platelets sample the wall. With Peclet numbers in the range (103 - 105) , simple diffusive arguments are not sufficient to explain the high rates of platelet adsorption. Using Stokes flow simulations, we show that the platelets' wall sampling rate is significantly increased by interactions with red blood cells. Our simulation models platelets as rigid bodies suspended in a Stokesian linear shear flow. We solve for the flow using standard boundary integral techniques with the appropriate single wall bounded Green's function. Receptor-ligand interactions are represented as Hookean springs with characteristic lifetimes, sizes, and stiffness coefficients. Drag forces are calculated with the reciprocal theorem, and RBC collisions are modelled as AR processes extracted from the large scale suspension simulations of Zhao et al.

  9. Platelet Function During Hypothermia in Experimental Mock Circulation.

    PubMed

    Van Poucke, Sven; Stevens, Kris; Kicken, Cécile; Simons, Antoine; Marcus, Abraham; Lancé, Marcus

    2016-03-01

    Alterations in platelet function are a common finding in surgical procedures involving cardiopulmonary bypass and hypothermia. Although the combined impact of hypothermia and artificial circulation on platelets has been studied before, the ultimate strategy to safely minimize the risk for bleeding and thrombosis is yet unknown. The aim of this study was to evaluate the use of a mock circulation loop to study the impact of hypothermia for platelet-related hemostatic changes. Venous blood was collected from healthy adult humans (n = 3). Closed mock circulation loops were assembled, each consisting of a centrifugal pump, an oxygenator with integrated heat exchanger, and a hardshell venous reservoir. The experiment started with the mock circulation temperature set at 37°C (T0 [0 h]). Cooling was then initiated at T1 (+2 h), where temperature was adjusted from 37°C to 32°C. Hypothermia was maintained from T2 (+4 h) to T3 (+28 h). From that point in time, rewarming from 32°C to 37°C was initiated with similar speed as cooling. From time point T4 (+30 h), normothermia (37°C) was maintained until the experiment ended at T5 (+32 h). Blood samples were analyzed in standard hematological tests: light transmission aggregometry (LTA) (arachidonic acid [AA], adenosine diphosphate [ADP], collagen [COL], thrombin-receptor-activating-peptide-14 [TRAP]), multiple electrode aggregometry (MEA) (AA, ADP, COL, TRAP), and rotational thromboelastometry (ROTEM) (EXTEM, FIBTEM, PLTEM). Hemoglobin, hematocrit, and platelet count decrease more substantially during temperature drop (37-32°C) than during hypothermia maintenance. Hb and Hct continue to follow this trend during active rewarming (32-37°C). PC increase from the moment active rewarming was initiated. None of the values return to the initial values. LTA values demonstrate a similar decrease in aggregation after stimulation with the platelet agonists between the start of the mock circulation and the start of cooling. Except

  10. New gene functions in megakaryopoiesis and platelet formation

    PubMed Central

    Gieger, Christian; Radhakrishnan, Aparna; Cvejic, Ana; Tang, Weihong; Porcu, Eleonora; Pistis, Giorgio; Serbanovic-Canic, Jovana; Elling, Ulrich; Goodall, Alison H.; Labrune, Yann; Lopez, Lorna M.; Mägi, Reedik; Meacham, Stuart; Okada, Yukinori; Pirastu, Nicola; Sorice, Rossella; Teumer, Alexander; Voss, Katrin; Zhang, Weihua; Ramirez-Solis, Ramiro; Bis, Joshua C.; Ellinghaus, David; Gögele, Martin; Hottenga, Jouke-Jan; Langenberg, Claudia; Kovacs, Peter; O’Reilly, Paul F.; Shin, So-Youn; Esko, Tõnu; Hartiala, Jaana; Kanoni, Stavroula; Murgia, Federico; Parsa, Afshin; Stephens, Jonathan; van der Harst, Pim; van der Schoot, C. Ellen; Allayee, Hooman; Attwood, Antony; Balkau, Beverley; Bastardot, François; Basu, Saonli; Baumeister, Sebastian E.; Biino, Ginevra; Bomba, Lorenzo; Bonnefond, Amélie; Cambien, François; Chambers, John C.; Cucca, Francesco; D’Adamo, Pio; Davies, Gail; de Boer, Rudolf A.; de Geus, Eco J. C.; Döring, Angela; Elliott, Paul; Erdmann, Jeanette; Evans, David M.; Falchi, Mario; Feng, Wei; Folsom, Aaron R.; Frazer, Ian H.; Gibson, Quince D.; Glazer, Nicole L.; Hammond, Chris; Hartikainen, Anna-Liisa; Heckbert, Susan R.; Hengstenberg, Christian; Hersch, Micha; Illig, Thomas; Loos, Ruth J. F.; Jolley, Jennifer; Khaw, Kay Tee; Kühnel, Brigitte; Kyrtsonis, Marie-Christine; Lagou, Vasiliki; Lloyd-Jones, Heather; Lumley, Thomas; Mangino, Massimo; Maschio, Andrea; Leach, Irene Mateo; McKnight, Barbara; Memari, Yasin; Mitchell, Braxton D.; Montgomery, Grant W.; Nakamura, Yusuke; Nauck, Matthias; Navis, Gerjan; Nöthlings, Ute; Nolte, Ilja M.; Porteous, David J.; Pouta, Anneli; Pramstaller, Peter P.; Pullat, Janne; Ring, Susan M.; Rotter, Jerome I.; Ruggiero, Daniela; Ruokonen, Aimo; Sala, Cinzia; Samani, Nilesh J.; Sambrook, Jennifer; Schlessinger, David; Schreiber, Stefan; Schunkert, Heribert; Scott, James; Smith, Nicholas L.; Snieder, Harold; Starr, John M.; Stumvoll, Michael; Takahashi, Atsushi; Tang, W. H. Wilson; Taylor, Kent; Tenesa, Albert; Thein, Swee Lay; Tönjes, Anke; Uda, Manuela; Ulivi, Sheila; van Veldhuisen, Dirk J.; Visscher, Peter M.; Völker, Uwe; Wichmann, H.-Erich; Wiggins, Kerri L.; Willemsen, Gonneke; Yang, Tsun-Po; Zhao, Jing Hua; Zitting, Paavo; Bradley, John R.; Dedoussis, George V.; Gasparini, Paolo; Hazen, Stanley L.; Metspalu, Andres; Pirastu, Mario; Shuldiner, Alan R.; van Pelt, L. Joost; Zwaginga, Jaap-Jan; Boomsma, Dorret I.; Deary, Ian J.; Franke, Andre; Froguel, Philippe; Ganesh, Santhi K.; Jarvelin, Marjo-Riitta; Martin, Nicholas G.; Meisinger, Christa; Psaty, Bruce M.; Spector, Timothy D.; Wareham, Nicholas J.; Akkerman, Jan-Willem N.; Ciullo, Marina; Deloukas, Panos; Greinacher, Andreas; Jupe, Steve; Kamatani, Naoyuki; Khadake, Jyoti; Kooner, Jaspal S.; Penninger, Josef; Prokopenko, Inga; Stemple, Derek; Toniolo, Daniela; Wernisch, Lorenz; Sanna, Serena; Hicks, Andrew A.; Rendon, Augusto; Ferreira, Manuel A.; Ouwehand, Willem H.; Soranzo, Nicole

    2012-01-01

    Platelets are the second most abundant cell type in blood and are essential for maintaining haemostasis. Their count and volume are tightly controlled within narrow physiological ranges, but there is only limited understanding of the molecular processes controlling both traits. Here we carried out a high-powered meta-analysis of genome-wide association studies (GWAS) in up to 66,867 individuals of European ancestry, followed by extensive biological and functional assessment. We identified 68 genomic loci reliably associated with platelet count and volume mapping to established and putative novel regulators of megakaryopoiesis and platelet formation. These genes show megakaryocyte-specific gene expression patterns and extensive network connectivity. Using gene silencing in Danio rerio and Drosophila melanogaster, we identified 11 of the genes as novel regulators of blood cell formation. Taken together, our findings advance understanding of novel gene functions controlling fate-determining events during megakaryopoiesis and platelet formation, providing a new example of successful translation of GWAS to function. PMID:22139419

  11. Sub-cellular modeling of platelet transport in blood flow through microchannels with constriction.

    PubMed

    Yazdani, Alireza; Karniadakis, George Em

    2016-05-11

    Platelet transport through arterial constrictions is one of the controlling processes influencing their adhesive functions and the formation of thrombi. We perform high-fidelity mesoscopic simulations of blood flow in microchannels with constriction, resembling arterial stenoses. The wall shear rates inside the constrictions reach levels as high as ≈8000 s(-1), similar to those encountered in moderate atherosclerotic plaques. Both red blood cells and platelets are resolved at sub-cellular resolution using the Dissipative Particle Dynamics (DPD) method. We perform a systematic study on the red blood cell and platelet transport by considering different levels of constriction, blood hematocrit and flow rates. We find that higher levels of constriction and wall shear rates lead to significantly enhanced margination of platelets, which may explain the experimental observations of enhanced post-stenosis platelet aggregation. We also observe similar margination effects for stiff particles of spherical shapes such as leukocytes. To our knowledge, such numerical simulations of dense blood through complex geometries have not been performed before, and our quantitative findings could shed new light on the associated physiological processes such as ATP release, plasma skimming, and thrombus formation. PMID:27087267

  12. [Single-donor (apheresis) platelets and pooled whole-blood-derived platelets--significance and assessment of both blood products].

    PubMed

    Hitzler, Walter E

    2014-01-01

    The transfusion efficacy of ATK, which contain fully functional platelets, is beyond all doubt. The equivalence of ATK and PTK has been subject of many studies. Some of those studies show the superiority of ATK's, while others do not, but there have been no studies that demonstrated a superiority of PTK's. The superiority of platelets stored in plasma and in third generation additive solution was demonstrated in clinical studies; therefore, it cannot be said that all the platelet concentrates on the German market are equivalent in efficacy. Of decisive importance, above all, is the risk of transfusion-transmitted infections with known pathogens, or those not yet discovered. This risk is different for ATK compared to PTK. Taking this difference in risk and the difference in donor exposure of transfused patients into account, it can definitely be said that ATK and PTK are not equivalent. In 2012, the Robert-Koch-Institute (RKI) published a mathematical risk model for different platelet concentrates and assessed the risk of transmitting known pathogens such as HIV, HCV, and HBV. The risk was higher for PTK compared to ATK. The relative risks for PTK derived from 4BCs were 2.2 (95%--CI: 2.1-2.4) for HIV, 2.7 (95%--CI: 2.5-3.0) for HCV, and 2.2 (95%--CI: 2.8-3.7) for HBV. At the present time, these are the relative risks of transfusion-transmitted infections with the traditional pathogens for PTK compared to ATK. In addition to the RKI assessed risks, there is the theoretical risk of a new, unknown agent, transmitted through blood exposure. The magnitude of this risk is hardly predictable for PTK. The experience gathered so far, especially in the last three decades, with the emergence of HIV, prions, and West Nil virus, shows that the biological nature of a next transfusion-transmissible infectious agent cannot be predictable. This agent, if we think at a conventional sexually transmissible agent with nucleic acid and long latent period, would spread first in areas with

  13. Multiscale Particle-Based Modeling of Flowing Platelets in Blood Plasma Using Dissipative Particle Dynamics and Coarse Grained Molecular Dynamics

    PubMed Central

    Zhang, Peng; Gao, Chao; Zhang, Na; Slepian, Marvin J.; Deng, Yuefan; Bluestein, Danny

    2014-01-01

    We developed a multiscale particle-based model of platelets, to study the transport dynamics of shear stresses between the surrounding fluid and the platelet membrane. This model facilitates a more accurate prediction of the activation potential of platelets by viscous shear stresses - one of the major mechanisms leading to thrombus formation in cardiovascular diseases and in prosthetic cardiovascular devices. The interface of the model couples coarse-grained molecular dynamics (CGMD) with dissipative particle dynamics (DPD). The CGMD handles individual platelets while the DPD models the macroscopic transport of blood plasma in vessels. A hybrid force field is formulated for establishing a functional interface between the platelet membrane and the surrounding fluid, in which the microstructural changes of platelets may respond to the extracellular viscous shear stresses transferred to them. The interaction between the two systems preserves dynamic properties of the flowing platelets, such as the flipping motion. Using this multiscale particle-based approach, we have further studied the effects of the platelet elastic modulus by comparing the action of the flow-induced shear stresses on rigid and deformable platelet models. The results indicate that neglecting the platelet deformability may overestimate the stress on the platelet membrane, which in turn may lead to erroneous predictions of the platelet activation under viscous shear flow conditions. This particle-based fluid-structure interaction multiscale model offers for the first time a computationally feasible approach for simulating deformable platelets interacting with viscous blood flow, aimed at predicting flow induced platelet activation by using a highly resolved mapping of the stress distribution on the platelet membrane under dynamic flow conditions. PMID:25530818

  14. Development of a New Method for Platelet Function Test and Its Shearing Condition in Microfludic System

    NASA Astrophysics Data System (ADS)

    Lee, Hoyoon; Kim, Gyehyu; Choi, Seawhan; Shin, Sehyun; Korea University Department of Mechanical Engineering Team

    2015-11-01

    Platelet is a crucial blood cell on hemostasis. As platelet exposed to high shear stress, it can be activated showing morphological and functional changes to stop bleeding. When platelet is abnormal, there is high risk of cardiovascular diseases. Thus, quick and precise assay for platelet function is important in clinical treatment. In this study, we design a microfluidic system, which can test platelet function exposed with the stimulation of shear and agonists. The microfluidic system consists of three parts: 1) a shear mechanism with rotating stirrer; 2) multiple microchannels to flow samples and to stop; 3) camera-interfaced migration distance(MD) analyzing system. When sheared blood is driven by pressure through the microchannel, shear-activated platelets adhere to a collagen-coated surface, causing blood flow to significantly slow and eventually stop. As the micro-stirrer speed increases, MD decreases exponentially at first, but it increases beyond a critical rpm after all. These results are coincident with data measured by FACS flowcytometry. These results imply that the present system could quantitatively measure the degree of activation, aggregation and adhesion of platelets and that blood MD is potent index for measuring the shear-dependence of platelet function.

  15. Pleural tissue repair with cord blood platelet gel

    PubMed Central

    Rosso, Lorenzo; Parazzi, Valentina; Damarco, Francesco; Righi, Ilaria; Santambrogio, Luigi; Rebulla, Paolo; Gatti, Stefano; Ferrero, Stefano; Nosotti, Mario; Lazzari, Lorenza

    2014-01-01

    Background Prolonged air leak is the major cause of morbidity after pulmonary resection. In this study we used in vitro and in vivo experiments to investigate an innovative approach based on the use of human umbilical cord blood platelet gel. Materials and methods In vitro, a scratch assay was performed to test the tissue repair capability mediated by cord blood platelet gel compared to the standard culture conditions using human primary mesothelial cells. In vivo, an iatrogenic injury was made to the left lung of 54 Wistar rats. Cord blood platelet gel was placed on the injured area only in treated animals and at different times histological changes and the presence of pleural adhesions were evaluated. In addition, changes in the pattern of soluble inflammatory factors were investigated using a multiplex proteome array. Results In vitro, mesothelial cell damage was repaired in a shorter time by cord blood platelet gel than in the control condition (24 versus 35 hours, respectively). In vivo, formation of new mesothelial tissue and complete tissue recovery were observed at 45±1 and 75±1 hours in treated animals and at 130±2.5 and 160±6 hours in controls, respectively. Pleural adhesions were evident in 43% of treated animals compared to 17% of controls. No complications were observed. Interestingly, some crucial soluble factors involved in inflammation were significantly reduced in treated animals. Discussion Cord blood platelet gel accelerates the repair of pleural damage and stimulates the development of pleural adhesions. Both properties could be particularly useful in the management of prolonged air leak, and to reduce inflammation. PMID:23736928

  16. Differences in Platelet Function In Patients with Acute Myeloid Leukaemia and Myelodysplasia Compared to Equally Thrombocytopenic Patients with Immune Thrombocytopenia

    PubMed Central

    Psaila, Bethan; Bussel, James B.; Frelinger, Andrew L.; Babula, Bracken; Linden, Matthew D.; Li, Youfu; Barnard, Marc R.; Tate, Chinara; Feldman, Eric J.; Michelson, Alan D.

    2011-01-01

    Background Severe thrombocytopenia is a major risk factor for haemorrhage, and yet platelet function and bleeding risk at low platelet counts are poorly understood because of limitations of platelet function testing at very low platelet counts. Objectives To examine and compare platelet function in severely thrombocytopenic patients with acute myeloid leukaemia (AML) or myelodysplasia (MDS) to patients with immune thrombocytopenia (ITP). Methods Whole blood flow cytometric measurement of platelet activation and platelet reactivity to agonists was correlated with the immature platelet fraction (IPF) and bleeding symptoms. Results Compared with patients with ITP, patients with AML/MDS had smaller platelets, lower IPF, and substantially lower platelet surface expression of activated GPIIb/IIIa and GPIb both with and without addition of ex vivo ADP or TRAP. In both ITP and AML/MDS, increased platelet surface GPIb on circulating platelets and expression of activated GPIIb/IIIa and GPIb on ex vivo activated platelets correlated with a higher IPF. Whereas platelet reactivity was higher for AML/MDS patients with bleeding than those with no bleeding, platelet reactivity was lower for ITP patients with bleeding than those with no bleeding. Conclusions AML/MDS patients have lower in vivo platelet activation and ex vivo platelet reactivity than patients with ITP. The proportion of newly-produced platelets correlates with the expression of platelet surface markers of activation. These differences might contribute to differences in bleeding tendency between AML/MDS and ITP. This study is the first to define differences in platelet function between AML/MDS patients and ITP patients with equivalent degrees of thrombocytopenia. PMID:21920014

  17. Proteins, Platelets, and Blood Coagulation at Biomaterial Interfaces

    PubMed Central

    Xu, Li-Chong; Bauer, James; Siedlecki, Christopher A.

    2015-01-01

    Blood coagulation and platelet adhesion remain major impediments to the use of biomaterials in implantable medical devices. There is still significant controversy and question in the field regarding the role that surfaces play in this process. This manuscript addresses this topic area and reports on state of the art in the field. Particular emphasis is placed on the subject of surface engineering and surface measurements that allow for control and observation of surface-mediated biological responses in blood and test solutions. Appropriate use of surface texturing and chemical patterning methodologies allow for reduction of both blood coagulation and platelet adhesion, and new methods of surface interrogation at high resolution allow for measurement of the relevant biological factors. PMID:25448722

  18. Mach-Zehnder interferometer for separation of platelets from red blood cells using dielectrophoretics

    NASA Astrophysics Data System (ADS)

    Shwetha, M.; Narayan, K.

    2016-03-01

    In this work, separation of platelets from red blood cells using Mach-Zehnder interferometer is shown using Dielectrophoretics (DEP). The proposed model demonstrates continuous separation of platelets from red blood cells. Mach-Zehnder Interferometer (MZI) has two arms, in which sensing arm will sense according to the applied voltage and separate the platelets from mixed blood cells. The platelets and the red blood cells will flow in two outlets of MZI. Microfluidic device is used to separate the RBC's and the platelets from the mixed blood cells.

  19. Resveratrol preserves the function of human platelets stored for transfusion.

    PubMed

    Lannan, Katie L; Refaai, Majed A; Ture, Sara K; Morrell, Craig N; Blumberg, Neil; Phipps, Richard P; Spinelli, Sherry L

    2016-03-01

    Stored platelets undergo biochemical, structural and functional changes that lead to decreased efficacy and safety of platelet transfusions. Not only do platelets acquire markers of activation during storage, but they also fail to respond normally to agonists post-storage. We hypothesized that resveratrol, a cardioprotective antioxidant, could act as a novel platelet storage additive to safely prevent unwanted platelet activation during storage, while simultaneously preserving normal haemostatic function. Human platelets treated with resveratrol and stored for 5 d released less thromboxane B2 and prostaglandin E2 compared to control platelets. Resveratrol preserved the ability of platelets to aggregate, spread and respond to thrombin, suggesting an improved ability to activate post-storage. Utilizing an in vitro model of transfusion and thromboelastography, clot strength was improved with resveratrol treatment compared to conventionally stored platelets. The mechanism of resveratrol's beneficial actions on stored platelets was partly mediated through decreased platelet apoptosis in storage, resulting in a longer half-life following transfusion. Lastly, an in vivo mouse model of transfusion demonstrated that stored platelets are prothrombotic and that resveratrol delayed vessel occlusion time to a level similar to transfusion with fresh platelets. We show resveratrol has a dual ability to reduce unwanted platelet activation during storage, while preserving critical haemostatic function. PMID:26683619

  20. Imaging and Elastometry of Blood Clots Using Magnetomotive Optical Coherence Tomography and Labeled Platelets

    PubMed Central

    Oldenburg, Amy L.; Wu, Gongting; Spivak, Dmitry; Tsui, Frank; Wolberg, Alisa S.; Fischer, Thomas H.

    2013-01-01

    Improved methods for imaging and assessment of vascular defects are needed for directing treatment of cardiovascular pathologies. In this paper, we employ magnetomotive optical coherence tomography (MMOCT) as a platform both to detect and to measure the elasticity of blood clots. Detection is enabled through the use of rehydrated, lyophilized platelets loaded with superparamagnetic iron oxides (SPIO-RL platelets) that are functional infusion agents that adhere to sites of vascular endothelial damage. Evidence suggests that the sensitivity for detection is improved over threefold by magnetic interactions between SPIOs inside RL platelets. Using the same MMOCT system, we show how elastometry of simulated clots, using resonant acoustic spectroscopy, is correlated with the fibrin content of the clot. Both methods are based upon magnetic actuation and phase-sensitive optical monitoring of nanoscale displacements using MMOCT, underscoring its utility as a broad-based platform to detect and measure the molecular structure and composition of blood clots. PMID:23833549

  1. Platelets

    MedlinePlus

    ... are related to immunity and fighting infection. Platelet Production Platelets are produced in the bone marrow, the ... platelet destruction and also decreased bone marrow platelet production. These problems are caused by autoantibodies. Antibodies are ...

  2. Silica Nanoparticles Effects on Blood Coagulation Proteins and Platelets

    PubMed Central

    Gryshchuk, Volodymyr; Galagan, Natalya

    2016-01-01

    Interaction of nanoparticles with the blood coagulation is important prior to their using as the drug carriers or therapeutic agents. The aim of present work was studying of the primary effects of silica nanoparticles (SiNPs) on haemostasis in vitro. We studied the effect of SiNPs on blood coagulation directly estimating the activation of prothrombin and factor X and to verify any possible effect of SiNPs on human platelets. It was shown that SiNPs shortened coagulation time in APTT and PT tests and increased the activation of factor X induced by RVV possibly due to the sorption of intrinsic pathway factors on their surface. SiNPs inhibited the aggregation of platelet rich plasma induced by ADP but in the same time partially activated platelets as it was shown using flow cytometry. The possibility of SiNPs usage in nanomedicine is strongly dependant on their final concentration in bloodstream and the size of the particles that are used. However SiNPs are extremely promising as the haemostatic agents for preventing the blood loss after damage. PMID:26881078

  3. Changes in platelet morphology and function during 24 hours of storage.

    PubMed

    Braune, S; Walter, M; Schulze, F; Lendlein, A; Jung, F

    2014-01-01

    For in vitro studies assessing the interaction of platelets with implant materials, common and standardized protocols for the preparation of platelet rich plasma (PRP) are lacking, which may lead to non-matching results due to the diversity of applied protocols. Particularly, the aging of platelets during prolonged preparation and storage times is discussed to lead to an underestimation of the material thrombogenicity. Here, we study the influence of whole blood- and PRP-storage times on changes in platelet morphology and function. Blood from apparently healthy subjects was collected according to a standardized protocol and examined immediately after blood collection, four hours and twenty four hours later. The capability of platelets to adhere and form stable aggregates (PFA100, closure time) was examined in sodium citrate anticoagulated whole blood (WB) using the agonists equine type I collagen and epinephrine bitartrate (collagen/epinephrine) as well as equine type I collagen and adenosine-5'-diphosphate (collagen/ADP). Circulating platelets were quantified at each time point. Morphology of platelets and platelet aggregates were visualized microscopically and measured using an electric field multi-channel counting system (CASY). The percentage of activated platelets was assessed by means of P-selectin (CD62P) expression of circulating platelets. Furthermore, platelet factor 4 (PF4) release was measured in platelet poor plasma (PPP) at each time point. Whole blood PFA100 closure times increased after stimulation with collagen/ADP and collagen/epinephrine. Twenty four hours after blood collection, both parameters were prolonged pathologically above the upper limit of the reference range. Numbers of circulating platelets, measured in PRP, decreased after four hours, but no longer after twenty four hours. Mean platelet volumes (MPV) and platelet large cell ratios (P-LCR, 12 fL - 40 fL) decreased over time. Immediately after blood collection, no debris or platelet

  4. Bidirectional effects of dexmedetomidine on human platelet functions in vitro.

    PubMed

    Kawamoto, Shuji; Hirakata, Hideo; Sugita, Naoko; Fukuda, Kazuhiko

    2015-11-01

    Platelets express the imidazoline (I)-receptor, I1 and I2, as well as the α2-adrenoceptor. Although dexmedetomidine, a selective α2-adrenoceptor agonist with some affinity for the I-receptor is expected to affect platelet function, the effects of dexmedetomidine on platelet functions remain unclear. In the present study, we investigated the effects of dexmedetomidine on human platelet functions in vitro. The effects of dexmedetomidine on platelet aggregation were examined using aggregometers. The formation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in platelets was measured by an enzyme immunoassay. In addition, P-selectin expression in platelets was estimated by flow cytometry. We showed that dexmedetomidine enhances platelet aggregation. But in the presence of yohimbine, an α2-antagonist, dexmedetomidine suppressed platelet aggregation. Efaroxan, an I1-antagonist, and methylene blue, a soluble guanylate cyclase inhibitor, abolished the suppressive effect of dexmedetomidine, whereas idazoxan, an I2-antagonist, showed no effect. Dexmedetomidine suppressed cAMP formation and enhanced P-selectin expression in platelets, and these effects were inhibited by yohimbine. Dexmedetomidine increased cGMP formation in platelets in the presence of yohimbine, and this increase was suppressed by efaroxan. These results demonstrated that dexmedetomidine has both enhancing and suppressive effects on human platelet functions through its action on the α2-adrenoceptor and on the I1-imidazoline receptor, respectively. PMID:26435028

  5. Mesoscopic Modeling of Blood Clotting: Coagulation Cascade and Platelets Adhesion

    NASA Astrophysics Data System (ADS)

    Yazdani, Alireza; Li, Zhen; Karniadakis, George

    2015-11-01

    The process of clot formation and growth at a site on a blood vessel wall involve a number of multi-scale simultaneous processes including: multiple chemical reactions in the coagulation cascade, species transport and flow. To model these processes we have incorporated advection-diffusion-reaction (ADR) of multiple species into an extended version of Dissipative Particle Dynamics (DPD) method which is considered as a coarse-grained Molecular Dynamics method. At the continuum level this is equivalent to the Navier-Stokes equation plus one advection-diffusion equation for each specie. The chemistry of clot formation is now understood to be determined by mechanisms involving reactions among many species in dilute solution, where reaction rate constants and species diffusion coefficients in plasma are known. The role of blood particulates, i.e. red cells and platelets, in the clotting process is studied by including them separately and together in the simulations. An agonist-induced platelet activation mechanism is presented, while platelets adhesive dynamics based on a stochastic bond formation/dissociation process is included in the model.

  6. Cryopreservation of Autologous Blood (Red Blood Cells, Platelets and Plasma)

    NASA Astrophysics Data System (ADS)

    Ebine, Kunio

    Prevention of post-transfusion hepatitis is still a problem in cardiovascular surgery. We initiated the cryopreservation of autologous blood for the transfusion in elective cardiovascular surgery since 1981. This study includes 152 surgical cases in which autologous frozen, allogeneic frozen, and/or allogeneic non-frozen blood were used. In the 152 surgical cases, there were 69 cases in which autologous blood only (Group I) was used; 12 cases with autologous and allogeneic frozen blood (Group II); 46 cases with autologous and allgeneic frozen plus allogeneic non-frozen blood (Group III); and 25 cases with allogeneic frozen plus allogeneic non-frozen blood (Group IV). No hepatitis developed in Groups I (0%) and II (0%), but there was positive hepatitis in Groups III (4.3%) and IV (8.0%) . In 357 cases of those who underwent surgery with allogeneic non-frozen whole blood during the same period, the incidence rate of hepatitis was 13.7% (49/357). Patients awaiting elective surgery can store their own blood in the frozen state. Patients who undergo surgery with the cryoautotransfusion will not produce any infections or immunologic reactions as opposed to those who undergo surgery with the allogeneic non-frozen blood.

  7. Red Blood Cell Hematocrit Influences Platelet Adhesion Rate in a Microchannel

    NASA Astrophysics Data System (ADS)

    Spann, Andrew; Campbell, James; Fitzgibbon, Sean; Rodriguez, Armando; Shaqfeh, Eric

    2014-11-01

    The creation of a blood clot to stop bleeding involves platelets forming a plug at the site of injury. Red blood cells indirectly play a role in ensuring that the distribution of platelets across the height of the channel is not uniform - the contrast in deformability and size between platelets and red blood cells allows the platelets to preferentially marginate close to the walls. We perform 3D boundary integral simulations of a suspension of platelets and red blood cells in a periodic channel with a model that allows for platelet binding at the walls. The relative rate of platelet activity with varying hematocrit (volume fraction of red blood cells) is compared to experiments in which red blood cells and platelets flow through a channel coated with von Willebrand factor. In the simulations as well as the experiments, a decrease in hematocrit of red blood cells is found to reduce the rate at which platelets adhere to the channel wall in a manner that is both qualitatively and quantitatively similar. We conclude with a discussion of the tumbling and wobbling motions of platelets in 3D leading up to the time at which the platelets bind to the wall. Funded by Stanford Army High Performance Computing Research Center, experiments by US Army Institute of Surgical Research.

  8. Thrombin-Mediated Platelet Activation of Lysed Whole Blood and Platelet-Rich Plasma: A Comparison Between Platelet Activation Markers and Ultrastructural Alterations.

    PubMed

    Augustine, Tanya N; van der Spuy, Wendy J; Kaberry, Lindsay L; Shayi, Millicent

    2016-06-01

    Platelet ultrastructural alterations representing spurious activation have been identified in pathological conditions. A limitation of platelet studies is that sample preparation may lead to artifactual activation processes which may confound results, impacting the use of scanning electron microscopy as a supplemental diagnostic tool. We used scanning electron microscopy and flow cytometry to analyze platelet activation in platelet-rich plasma (PRP) and whole blood (WB) samples. PRP generated using a single high g force centrifugation, and WB samples treated with a red blood cell lysis buffer, were exposed to increasing concentrations of the agonist thrombin. Platelets in lysed WB samples responded to thrombin by elevating the activation marker CD62p definitively, with corresponding ultrastructural changes indicating activation. Conversely, CD62p expression in PRP preparations remained static. Ultrastructural analysis revealed fully activated platelets even under low concentration thrombin stimulation, with considerable fibrin deposition. It is proposed that the method for PRP production induced premature platelet activation, preventable by using an inhibitor of platelet aggregation and fibrin polymerization. Nevertheless, our results show a definitive correspondence between flow cytometry and scanning electron microscopy in platelet activation studies, highlighting the potential of the latter technique as a supplemental diagnostic tool. PMID:27329313

  9. Variable Effect of P2Y12 Inhibition on Platelet Thrombus Volume in Flowing Blood

    PubMed Central

    Mendolicchio, G. L.; Zavalloni, D.; Bacci, M.; Corrada, E.; Marconi, M.; Lodigiani, C.; Presbitero, P.; Rota, L.; Ruggeri, Z. M.

    2010-01-01

    Background and objectives Patients treated by percutaneous coronary intervention (PCI) receive aspirin and P2Y12 ADP receptor inhibitors to reduce thrombotic complications. The choice of methodology for monitoring the effects of treatment and assessing its efficacy is still a topic of debate. We evaluated how decreased P2Y12 function influences platelet aggregate (thrombus) size measured ex vivo. Methods and Results We used confocal videomicroscopy to measure in real time the volume of platelet thrombi forming upon blood perfusion over fibrillar collagen type I at the wall shear rate of 1,500 s−1. The average volume was significantly smaller in 31 patients receiving aspirin and clopidogrel (19) or ticlopidine (12) than 21 controls, but individual values were above the lower limit of the normal distribution, albeit mostly within the lower quartile, in 61.3% of cases. Disaggregation of platelet thrombi at later perfusion times occurred frequently in the patients. Vasodilator-stimulated phosphoprotein (VASP) phosphorylation, reflecting P2Y12 inhibition, was also decreased in the patient group and only 22.6% of individual values were above the lower normal limit. We found no correlation between thrombus volume formed onto collagen fibrils and level of P2Y12 inhibition, suggesting that additional and individually variable factors can influence the inhibitory effect of treatment on platelet function. Conclusions Measuring platelet thrombus formation in flowing blood reflects the consequences of anti-platelet therapy in a manner that is not proportional to P2Y12 inhibition. Combining the results of the two assays may improve the assessment of thrombotic risk. PMID:21083646

  10. Biochemical and functional abnormalities in hypercholesterolemic rabbit platelets

    SciTech Connect

    Dalal, K.B.; Ebbe, S.; Mazoyer, E.; Carpenter, D.; Yee, T. )

    1990-02-01

    This study was designed to elucidate changes in rabbit platelet lipids induced by a cholesterol rich diet and to explore the possible correlation of these lipid changes with platelet abnormalities. Pronounced biochemical alterations were observed when serum cholesterol levels of 700-1000 mg% were reached. Hypercholesterolemic (HC) platelets contained 37% more neutral lipids and 16% less phospholipids than the controls. Lysolecithin, cholesterol esters and phosphatidylinositol (PI) levels were increased in HC platelets, and the levels of phosphatidylcholine (PC) were decreased. The cholesterol/phospholipid molar ratio of lipidemic platelets increased from 0.55 +/- 0.011 to 0.89 +/- 0.016 (P less than 0.01) in eight weeks. HC platelets had 90% more arachidonic acid (AA) in the PI than normal platelets. No significant changes in AA of PC were observed. Platelet function was monitored by the uptake and release of (14C)serotonin in platelet rich plasma (PRP), using varying concentrations of collagen as an aggregating agent. The uptake of (14C)serotonin in HC and normal platelets ranged from 78-94%. The percent of (14C)serotonin released from normal and HC platelets was proportional to the concentration of collagen. However, lipidemic platelets were hyperreactive to low concentrations of collagen. Incorporation of 50 microM acetylsalicylic acid into the aggregating medium suppressed the release of (14C)serotonin in normal PRP by more than 90%, but had only a partial effect on lipidemic PRP.

  11. Lactodifucotetraose, a human milk oligosaccharide, attenuates platelet function and inflammatory cytokine release.

    PubMed

    Newburg, David S; Tanritanir, Ayse C; Chakrabarti, Subrata

    2016-07-01

    Human milk strongly quenches inflammatory processes in vitro, and breastfed infants have lower incidence of inflammatory diseases than those fed artificially. Platelets from neonates, in contrast to those from adults, are less responsive to platelet agonists such as collagen, thrombin, ADP, and epinephrine. Breastfed infants absorb oligosaccharides intact from the human milk in their gut to the circulation. This study was to determine whether these oligosaccharides can attenuate platelet function and platelet secretion of pro-inflammatory proteins, and to identify the active component. The natural mixture of oligosaccharides from human milk and pure individual human milk oligosaccharides were tested for their ability to modulate responses of platelets isolated from human blood following exposure to thrombin, ADP, and collagen. Human milk and the natural mixture of human milk oligosaccharides inhibited platelet release of inflammatory proteins. Of the purified human milk oligosaccharides tested, only lactodifucotetraose (LDFT) significantly inhibited thrombin induced release of the pro-inflammatory proteins RANTES and sCD40L. LDFT also inhibited platelet adhesion to a collagen-coated surface, as well as platelet aggregation induced by ADP or collagen. These data indicate that LDFT may help modulate hemostasis by suppressing platelet-induced inflammatory processes in breastfed infants. This activity suggests further study of LDFT for its potential as a therapeutic agent in infants and adults. PMID:26743063

  12. Platelet Function Tests: A Review of Progresses in Clinical Application

    PubMed Central

    Choi, Jae-Lim; Li, Shuhua

    2014-01-01

    The major goal of traditional platelet function tests has been to screen and diagnose patients who present with bleeding problems. However, as the central role of platelets implicated in the etiology of arterial thrombotic diseases such as myocardial infarction and stroke became widely known, platelet function tests are now being promoted to monitor the efficacy of antiplatelet drugs and also to potentially identify patients at increased risk of thrombosis. Beyond hemostasis and thrombosis, an increasing number of studies indicate that platelets play an integral role in intercellular communication, are mediators of inflammation, and have immunomodulatory activity. As new potential biomarkers and technologies arrive at the horizon, platelet functions testing appears to take on a new aspect. This review article discusses currently available clinical application of platelet function tests, placing emphasis on essential characteristics. PMID:24895576

  13. Effects of Physical (In)activity on Platelet Function

    PubMed Central

    Heber, Stefan; Volf, Ivo

    2015-01-01

    As platelet activation is closely related to the liberation of growth factors and inflammatory mediators, platelets play a central role in the development of CVD. Virtually all cardiovascular risk factors favor platelet hyperreactivity and, accordingly, also physical (in)activity affects platelet function. Within this paper, we will summarize and discuss the current knowledge on the impact of acute and habitual exercise on platelet function. Although there are apparent discrepancies regarding the reported effects of acute, strenuous exercise on platelet activation, a deeper analysis of the available literature reveals that the applied exercise intensity and the subjects' cardiorespiratory fitness represent critical determinants for the observed effects. Consideration of these factors leads to the summary that (i) acute, strenuous exercise can lead to platelet activation, (ii) regular physical activity and/or physical fitness diminish or prevent platelet activation in response to acute exercise, and (iii) habitual physical activity and/or physical fitness also favorably modulate platelet function at physical rest. Notably, these effects of exercise on platelet function show obvious similarities to the well-recognized relation between exercise and the risk for cardiovascular events where vigorous exercise transiently increases the risk for myocardial infarction and a physically active lifestyle dramatically reduces cardiovascular mortality. PMID:26557653

  14. Effect in vitro on platelet function of two compounds developed from the pyrimido-pyrimidines

    PubMed Central

    Slater, S. D.; Turpie, A. G. G.; Douglas, A. S.; McNicol, G. P.

    1972-01-01

    VK 774 and VK 744, two new compounds developed from the pyrimido-pyrimidines, have been found to be powerful inhibitors of platelet function tested in vitro. They inhibit adenosine diphosphate (ADP)-induced platelet aggregation, and the release of platelet factor 3 by kaolin, and VK 774 also reduces platelet adhesiveness and inhibits platelet aggregation (`snowstorm' effect) in the Chandler tube system. Although measured percentage whole blood clot retraction was uninfluenced by these drugs the clot produced with VK 774 was friable and soft. VK 774 appears to be the most powerful of these compounds reported so far, being active in some test systems at 10−6M, and, if the results of toxicity testing are satisfactory, it should be an important agent for therapeutic trial. PMID:5046075

  15. The effect of time of day and exercise on platelet functions and platelet-neutrophil aggregates in healthy male subjects.

    PubMed

    Aldemir, Hatice; Kiliç, Nedret

    2005-12-01

    Platelet activation state changes by exercise. The effect of exercise time on platelet activation state and formation of platelet-neutrophil aggregates are not known yet. In this study the effect of exercise and time of day were examined on platelet activity with platelet-neutrophil aggregates. Ten moderately active males aged 27+/- 1.63 (mean+/-S.D.) years completed sub-maximal (70% VO(2max)) exercise trials for 30 min. Blood pressure (BP) was recorded. Venous blood samples were obtained at rest, immediately post-exercise and after 30 min of recovery. Whole blood was analysed for haematocrit (Hct), haemoglobin (Hb), platelet count (PC), mean platelet count (MPV) and platelet aggregation (PA). Platelet-neutrophil aggregates and beta-thromboglobulin (beta-TG) levels were assayed. Platelet count showed significant increase after morning exercise ((236+/- 32)x10(9) l(-1) versus (202+/- 34)x10(9) l(-1) baseline, p < 0.05). Exercise resulted in significantly lower MPV after the evening exercise (9.16+/- 0.5 fl versus 9.65+/- 0.36 fl, p < 0.05). Platelet aggregation by adenosine diphosphate (ADP) decreased after morning exercise and the recovery aggregation levels were significantly different at two different times of the day (68+/- 20% a.m. versus 80+/- 12% p.m., p < 0.05). It was also showed that platelet-neutrophil aggregates increased significantly from baseline after both exercises. Exercise-induced platelet-neutrophil aggregates were higher in the evening (10.7+/- 1.3% p.m. versus 6.4+/- 1.8% a.m., p < 0.0001). It is therefore concluded that besides platelet-platelet aggregation, exercise can cause platelet- neutrophil aggregates. In addition, time of day has an effect on platelet activation related events. Circadian variations of physiological parameters may have an effect on thrombus formation by platelet activation. PMID:16311912

  16. Interaction of nanoparticles of ferric oxide with brain nerve terminals and blood platelets

    NASA Astrophysics Data System (ADS)

    Borisova, Tatiana; Krisanova, Natalia; Sivko, Roman; Borisov, Arseniy

    2012-07-01

    Nanoparticles of ferric oxide are the components of Lunar and Martian soil simulants. The observations suggest that exposure to Lunar soli simulant can be deleterious to human physiology and the components of lunar soil may be internalized by lung epithelium and may overcome the blood-brain barrier. The study focused on the effects of nanoparticles of ferric oxide on the functional state of rat brain nerve terminals (synaptosomes) and rabbit blood platelets. Using photon correlation spectroscopy, we demonstrated the binding of nanoparticles of ferric oxide with nerve terminals and platelets. Nanoparticles did not depolarize the plasma membrane of nerve terminals and platelets that was shown by fluorimetry with potential-sensitive fluorescent dye rhodamine 6G. Using pH-sensitive fluorescent dye acridine orange, we revealed that the acidification of synaptic vesicles of nerve terminals and secretory granules of platelets did not change in the presence of nanoparticles. The initial velocity of uptake of excitatory neurotransmitter glutamate was not influenced by nanoparticles of ferric oxide, whereas glutamate binding to nerve terminals was altered. Thus, it was suggested that nanoparticles of ferric oxide might disturb glutamate transport in the mammalian CNS.

  17. The interaction of selected semiconducting biomaterials with platelet-rich plasma and whole blood.

    PubMed

    Shih, Chun-Che; Shih, Chun-Ming; Su, Yea-Yang; Gerhardt, Rosario A; Lin, Shing-Jong

    2005-09-01

    Copper and silicon are used as biomaterials in various forms. Silicon is a well-known semiconductor and has two distinct types (n-type and p-type), depending on the dopants used. The oxides (e.g., CuO and Cu2O) on the copper surface also behave as semiconductors. The electrochemical properties of these two selected semiconducting biomaterials were investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and open-circuit potential (OCP) in an aerated Ringer's solution at 37 degrees C. Platelet-rich plasma (PRP) and whole blood from a healthy human donor were used to determine the degree of interaction with the selected semiconducting materials in vitro. Morphologies of adherent platelets and blood on these two biomaterials were examined by scanning electron microscopy (SEM). Experimental results indicated that the degree of interaction is a function of the electrochemical properties of these two biomaterials. Platelets and blood were found to react strongly with p-type biomaterials while little or no sign of interaction with n-type biomaterials was demonstrated. The difference in PRP and whole blood reactions between p-type and n-type semiconductors was quantified to be significant as p<0.05. PMID:16010666

  18. The Genetics of Common Variation affecting Platelet Development, Function and Pharmaceutical Targeting

    PubMed Central

    Johnson, Andrew D.

    2011-01-01

    Summary Common variant effects on human platelet function and response to anti-platelet treatment have traditionally been studied using candidate gene approaches involving a limited number of variants and genes. These studies have often been undertaken in clinically defined cohorts. More recently, studies have applied genome-wide scans in larger population samples than prior candidate studies, in some cases scanning relatively healthy individuals. These studies demonstrate synergy with some prior candidate gene findings (e.g., GP6, ADRA2A) but also uncover novel loci involved in platelet function. Here, I summarise findings on common genetic variation influencing platelet development, function and therapeutics. Taken together, candidate gene and genome-wide studies begin to account for common variation in platelet function and provide information that may ultimately be useful in pharmacogenetic applications in the clinic. More than 50 loci have been identified with consistent associations with platelet phenotypes in ≥2 populations. Several variants are under further study in clinical trials relating to anti-platelet therapies. In order to have useful clinical applications, variants must have large effects on a modifiable outcome. Regardless of clinical applications, studies of common genetic influences, even of small effect, offer additional insights into platelet biology including the importance of intracellular signalling and novel receptors. Understanding of common platelet-related genetics remains behind parallel fields (e.g., lipids, blood pressure) due to challenges in phenotype ascertainment. Further work is necessary to discover and characterise loci for platelet function, and to assess whether these loci contribute to disease aetiologies or response to therapeutics. PMID:21781261

  19. Imipramine binding in subpopulations of normal human blood platelets

    SciTech Connect

    Arora, R.C.; Meltzer, H.Y.

    1984-02-01

    Imipramine binding was studied in platelet membranes isolated with different proportions of heavy (young) and light (old) platelets. The B/sub max/, a measure of the number of binding sites, was greater in the heavier platelets than in the light platelets. However, the dissociation constant K/sub d/ (a reflection of the affinity of imipramine binding) was greater in the lighter platelets compared to the heavy platelets. These results indicate that differences in K/sub d/ and B/sub max/ in particular membrane preparation, could be due to the differences in the relative proportion of heavy and light platelets.

  20. Platelet Consumption by Arterial Prostheses: The Effects of Endothelialization and Pharmacologic Inhibition of Platelet Function

    PubMed Central

    Harker, Laurence A.; Slichter, Sherrill J.; Sauvage, Lester R.

    1977-01-01

    The thrombogenic mechanism of arterial grafts has been studied by determining the relative utilization of platelets, fibrinogen and plasminogen by human arterial prostheses, and by direct examination of arterial grafts in a baboon model. Forty-one survival and turnover measurements of 51Crplatelets, 131I-fibrinogen and 125I-plasminogen in ten patients with aortofemoral knitted Dacron prostheses demonstrated platelet consumption after graft placement (platelet survival 4.2 days ± 0.5 and turnover 68,000 plat/ul/day ±10,000 compared with 8.2 days ± 0.3 and 35,000 plat/ul/day ± 5,000 respectively for control subjects with stable vascular disease, p < 0.01). In vitro platelet function test results were normal. Platelet consumption was interrupted by dipyridamole or a combination of dipyridamole and acetylsalicylic acid, and platelet survival normalized spontaneously during nine months postoperatively. No significantly increased consumption of fibrinogen or plasminogen was found in these patients with arterial grafts. Placement of impervious knitted Dacron velour aortic grafts in baboons reproduced platelet consumption that progressively normalized over six weeks postoperatively. Platelet survival measurements correlated directly with endothelial cell coverage of the graft luminal surface in these animals implying that endothelialization of the graft surface was also occurring postoperatively in patients. ImagesFig. 4.Fig. 5. PMID:411428

  1. The caspase-3 inhibitor (peptide Z-DEVD-FMK) affects the survival and function of platelets in platelet concentrate during storage

    PubMed Central

    Shiri, Reza; Ahmadinejad, Minoo; Vaeli, Shahram; Tabatabaei, Mohammad Reza

    2014-01-01

    Background Although apoptosis occurs in nucleated cells, studies show that this event also occurs in some anucleated cells such as platelets. During storage of platelets, the viability of platelets decreased, storage lesions were observed, and cells underwent apoptosis. We investigated the effects of caspase-3 inhibitor on the survival and function of platelets after different periods of storage. Methods Platelet concentrates were obtained from the Iranian Blood Transfusion Organization in plastic blood bags. Caspase-3 inhibitor (Z-DEVD-FMK) was added to the bags. These bags along with control bags to which no inhibitor was added were stored in a shaking incubator at 22℃ for 7 days. The effects of Z-DEVD-FMK on the functionality of platelets were analyzed by assessing their ability to bind to von Willebrand factor (vWF) and to aggregate in the presence of arachidonic acid and ristocetin. Cell survival was surveyed by MTT assay. Results At day 4 of storage, ristocetin-induced platelet aggregation was significantly higher in the inhibitor-treated (test) than in control samples; the difference was not significant at day 7. There was no significant difference in arachidonic acid-induced platelet aggregation between test and control samples. However, at day 7 of storage, the binding of platelets to vWF was significantly higher in test than in control samples. The MTT assay revealed significantly higher viability in test than in control samples at both days of study. Conclusion Treatment of platelets with caspase-3 inhibitor could increase their functionality and survival. PMID:24724067

  2. Metastasis: new functional implications of platelets and megakaryocytes.

    PubMed

    Leblanc, Raphael; Peyruchaud, Olivier

    2016-07-01

    Platelets are essential components of hemostasis. Due to a plethora of factors released on activation, platelet functions are also connected to tumor growth, notably by acting on angiogenesis. It is now well recognized that major roles of platelets in the poor outcome of cancer patients occurs during hematogenous dissemination of cancer cells. In this review, we describe recent insights into the molecular mechanisms supporting the prometastatic activity of platelets. Platelets have been shown to promote survival of circulating tumor cells (CTCs) in the bloodstream by conferring resistance to the shear stress and attack from natural killer cells. Recently, platelets were found to promote and/or maintain the state of epithelial to mesenchymal transition on CTCs through platelet secretion of transforming growth factor β in response to CTC activation. At a later stage in the metastatic process, platelets promote extravasation and establishment of metastatic cells in distant organs as observed in bone. This particular environment is also the site of hematopoiesis, megakaryocytopoiesis, and platelet production. Increasing the number of megakaryocytes (MKs) in the bone marrow results in a high bone mass phenotype and inhibits skeletal metastasis formation of prostate cancer cells. As a result of their specific location in vascular niches in the bone marrow, MK activity might contribute to the "seed and soil" suitability between CTCs and bone. In conclusion, recent findings have made a great advance in our knowledge on how platelets contribute to the metastatic dissemination of cancer cells and that may support the development of new antimetastasis therapies. PMID:27154188

  3. Ultraviolet irradiation of platelet concentrate abrogates lymphocyte activation without affecting platelet function in vitro

    SciTech Connect

    Kahn, R.A.; Duffy, B.F.; Rodey, G.G.

    1985-11-01

    We studied the effect of ultraviolet (UV) radiation on platelet concentrates. Samples irradiated at 310 mm for 30 minutes at a dose of 1782 J per m2 showed no loss of platelet function in vitro as determined by adenosine diphosphate, collagen, or ristocetin-induced aggregation. Lymphocytes isolated from irradiated units were unable to act as responders or stimulators in a mixed-lymphocyte reaction. These data suggest that UV radiation of platelet concentrates may result in a cell suspension that is unable to evoke an immunological response.

  4. Ovine platelet function is unaffected by extracorporeal membrane oxygenation within the first 24 h.

    PubMed

    Hayes, Rylan A; Foley, Samuel; Shekar, Kiran; Diab, Sara; Dunster, Kimble R; McDonald, Charles; Fraser, John F

    2015-10-01

    This study investigated platelet dysfunction during short-term extracorporeal membrane oxygenation (ECMO) and secondarily to determine if hyperoxaemia contributes to this dysfunction. Healthy sheep were anaesthetized and maintained on ECMO for either 2 or 24 h, with or without induction of smoke inhalation acute lung injury. A specialized animal-operating theatre was used to conduct the experimentation. Forty-three healthy female sheep were randomized into either a test or a control group. Following anaesthesia, test groups received ECMO ± smoke inhalation acute lung injury (SALI), whereas control groups were maintained with ventilation only ± SALI. Physiological, biochemical and coagulation data were obtained throughout via continuous monitoring and blood sampling. Platelet function was quantified through whole blood impedance aggregometry using Multiplate. Ovine platelet activity induced by adenosine diphosphate (ADP) and collagen was unaffected during the first 24 h of ECMO. However, progressive divergence of ADP-induced platelet activity was noted at cessation of the experiment. PaO2 was inversely related to ADP-dependent platelet activity in the ECMO groups--a relationship not identified in the control groups. ADP and collagen-dependent platelet activity are not significantly affected within the first 24 h of ECMO in sheep. However, dysfunction in ADP-dependent platelet activity may have continued to develop if observed beyond 24 h. Hyperoxaemia during ECMO does appear to affect how platelets react to ADP and may contribute to this developing dysfunction. Long-term animal models and investigation in clinical animals are warranted to fully investigate platelet function during ECMO. PMID:26196193

  5. Decreased platelet function in aortic valve stenosis: high shear platelet activation then inactivation.

    PubMed Central

    O'Brien, J. R.; Etherington, M. D.; Brant, J.; Watkins, J.

    1995-01-01

    OBJECTIVE--To elucidate the mechanism of the bleeding tendency observed in patients with aortic valve stenosis. DESIGN--A prospective study of high and low shear platelet function tests in vitro in normal controls compared with that in patients with severe aortic valve stenosis with a mean (SD) systolic gradient by Doppler of 75 (18) mm Hg before and at least 4 months after aortic valve replacement. SETTING--District general hospital. RESULTS--The patients showed reduced retention in the high shear platelet function tests. (a) Platelet retention in the filter test was 53.6 (12.6)% in patients with aortic valve stenosis and 84.8 (9.6)% in the controls (P < 0.001). (b) Retention in the glass bead column test was 49.8 (19.2) in the patients and 87.4 (8.7) in the controls (P < 0.001). (c) The standard bleeding time was longer in the patients (P < 0.06). Results of the high shear tests (a, b, and c) after aortic valve replacement were within the normal range. The platelet count was low but within the normal range before surgery and increased postoperatively (P < 0.01). There were no differences in the results of standard clotting tests, plasma and intraplatelet von Willebrand's factor, or in 15 platelet aggregation tests using five agonists between patients with aortic valve stenosis and controls. CONCLUSIONS--The high shear haemodynamics of aortic valve stenosis modify platelet function in vivo predisposing to a bleeding tendency. This abnormality of platelet function is detectable only in vitro using high shear tests. The abnormal function is reversed by aortic valve replacement. High shear forces in vitro activate and then inactivate platelets. By the same mechanisms aortic valve stenosis seems to lead to high shear damage in vivo, resulting in a clinically important bleeding tendency in some patients. PMID:8541170

  6. A standardized technique for efficient platelet and leukocyte collection using the Model 30 Blood Processor.

    PubMed

    Aisner, J; Schiffer, C A; Wolff, J H; Wiernik, P H

    1976-01-01

    The Model 30 Blood Processor is a safe and simple means of harvesting blood cell components. Presently cell collection depends on a visual assessment by the operator of the indistinct boundaries of cell fractions. To determine when each cell component could best be harvested, serial samples were taken from the output port at fixed intervals anf the results of counts and differentials were graphed and tabulated. Studies in normal donors were done using acid-citrate-dextrose (ACD), 2 per cent sodium citrate in 6 per cent hydroxyethyl starch (HES), or heparin as anticoagulants. There was considerable overlap between the latter part of the platelet band, the leukocyte band and the rising hematocrit with all three anticoagulants. Normally functional lymphocytes could be harvested efficiently (approximately 80%) using ACD or heparin. Platelets could be harvested from ACD very efficiently (approximately 90%). Granulocytes could not be harvested from ACD (less than 10%) since they were dispersed in the red blood cell (RBC) layer. Using HES, granulocytes could be harvested efficiently (approximately 70%) by extending collection into the RBC layer. Based on these data, a standard technique for cell collection has been devised. The flow rate is slowed to 20 ml/min and collection is carried 30 ml (90 seconds at a rate of 20 ml/min) for platelets. The RBC loss is approximately 6 to 8 and 2 to 3 ml/pass respectively. These studies indicate that the Model 30 is a highly efficient apparatus for blood cell separation, but the volume of blood processed is limited by the intermittent blood flow. PMID:62425

  7. Morphological and functional platelet abnormalities in Berkeley sickle cell mice.

    PubMed

    Shet, Arun S; Hoffmann, Thomas J; Jirouskova, Marketa; Janczak, Christin A; Stevens, Jacqueline R M; Adamson, Adewole; Mohandas, Narla; Manci, Elizabeth A; Cynober, Therese; Coller, Barry S

    2008-01-01

    Berkeley sickle cell mice are used as animal models of human sickle cell disease but there are no reports of platelet studies in this model. Since humans with sickle cell disease have platelet abnormalities, we studied platelet morphology and function in Berkeley mice (SS). We observed elevated mean platelet forward angle light scatter (FSC) values (an indirect measure of platelet volume) in SS compared to wild type (WT) (37+/-3.2 vs. 27+/-1.4, mean+/-SD; p<0.001), in association with moderate thrombocytopenia (505+/-49 x 10(3)/microl vs. 1151+/-162 x 10(3)/microl; p<0.001). Despite having marked splenomegaly, SS mice had elevated levels of Howell-Jolly bodies and "pocked" erythrocytes (p<0.001 for both) suggesting splenic dysfunction. SS mice also had elevated numbers of thiazole orange positive platelets (5+/-1% vs. 1+/-1%; p<0.001), normal to low plasma thrombopoietin levels, normal plasma glycocalicin levels, normal levels of platelet recovery, and near normal platelet life spans. Platelets from SS mice bound more fibrinogen and antibody to P-selectin following activation with a threshold concentration of a protease activated receptor (PAR)-4 peptide compared to WT mice. Enlarged platelets are associated with a predisposition to arterial thrombosis in humans and some humans with SCD have been reported to have large platelets. Thus, additional studies are needed to assess whether large platelets contribute either to pulmonary hypertension or the large vessel arterial occlusion that produces stroke in some children with sickle cell disease. PMID:18374611

  8. Misshapen/NIK-related kinase (MINK1) is involved in platelet function, hemostasis, and thrombus formation.

    PubMed

    Yue, Ming; Luo, Dongjiao; Yu, Shanshan; Liu, Pu; Zhou, Qi; Hu, Mengjiao; Liu, Yangyang; Wang, Shuai; Huang, Qian; Niu, Yuxi; Lu, Linrong; Hu, Hu

    2016-02-18

    The sterile-20 kinase misshapen/Nck-interacting kinase (NIK)-related kinase 1 (MINK1) is involved in many important cellular processes such as growth, cytoskeletal rearrangement, and motility. Here, with MINK1-deficient (MINK1(-/-)) mice, we showed that MINK1 plays an important role in hemostasis and thrombosis via the regulation of platelet functions. In the tail-bleeding assay, MINK1(-/-) mice exhibited a longer bleeding time than wild-type (WT) mice (575.2 ± 59.7 seconds vs 419.6 ± 66.9 seconds). In a model of ferric chloride-induced mesenteric arteriolar thrombosis, vessel occlusion times were twice as long in MINK1(-/-) mice as in WT mice. In an in vitro microfluidic whole-blood perfusion assay, thrombus formation on a collagen matrix under arterial shear conditions was significantly reduced in MINK1(-/-) platelets. Moreover, MINK1(-/-) platelets demonstrated impaired aggregation and secretion in response to low doses of thrombin and collagen. Furthermore, platelet spreading on fibrinogen was largely hampered in MINK1(-/-) platelets. The functional differences of MINK1(-/-) platelets could be attributed to impaired adenosine 5'-diphosphate secretion. Signaling events associated with MINK1 appeared to involve extracellular signal-regulated kinase, p38, and Akt. Hence, MINK1 may be an important signaling molecule that mediates mitogen-activated protein kinase signaling and participates in platelet activation and thrombus formation. PMID:26598717

  9. An ethanol extract of Ramulus mori improves blood circulation by inhibiting platelet aggregation.

    PubMed

    Lee, Jiyun; Kwon, Gayeung; Park, Jieun; Kim, Jeong-Keun; Choe, Soo Young; Seo, Yoonhee; Lim, Young-Hee

    2016-07-01

    Inappropriate platelet aggregation can cause blood coagulation and thrombosis. In this study, the effect of an ethanol extract of Ramulus mori (ERM) on blood circulation was investigated. The antithrombotic activity of ERM on rat carotid arterial thrombosis was evaluated in vivo, and the effect of ERM on platelet aggregation and blood coagulation time was evaluated ex vivo. To evaluate the safety of ERM, its cytotoxicity to platelets and its effect on tail bleeding time were assessed; ERM was not toxic to rat platelets and did not prolong bleeding time. Moreover, administering ERM to rats had a significant preventive effect on carotid arterial thrombosis in vivo, and significantly inhibited adenosine diphosphate- and collagen-induced platelet aggregation ex vivo, whereas it did not prolong coagulation periods, such as prothrombin time and activated partial thromboplastin time. The results suggest that ERM is effective in improving blood circulation via antiplatelet activity rather than anticoagulation activity. PMID:26967156

  10. Interactions of human blood-platelets with vaccinia

    SciTech Connect

    Vernon, C.E.B.

    1989-01-01

    These investigations were conducted to determine whether vaccinia (strain WR) adsorbs to the human platelet and alters specific platelet activities, namely, the uptake of {sup 14}C-serotonin, the release of {sup 14}C-serotonin and also the release of {sup 14}C-serotonin stimulated by thrombin. Vaccinia did not alter the platelet uptake of {sup 14}C-serotonin. To determine if vaccinia induces a release of {sup 14}C-serotonin from platelets, vaccinia was added to washed or unwashed {sup 14}C-serotonin labeled platelets, and the release of {sup 14}C-Serotonin into the supernatant was measured. Less than 8% of the {sup 14}C-Serotonin was released. The action of vaccinia to alter the platelet release of {sup 14}C-serotonin induced by thrombin was monitored by measuring the radioactivity released from thrombin stimulated {sup 14}C-serotonin labeled platelets incubated with or without vaccinia. Vaccinia inhibited the thrombin induced release of {sup 14}C-serotonin from platelets at a virus to platelet ratios of 5 through 80 plaque forming units (p.f.u.)/platelet. The inhibition was dose dependent. The binding of virus to platelets was determined by a plaque assay of a washed mixture of vaccinia virus and platelets. After inoculation of mixture onto a monolayer of BSC40 cells at a virus to platelet ratio of 0.1 p.f.u./platelet, 50 cell-bound-virus per 130,000-150,000 platelets were enumerated. Vaccinia was observed to inhibit the thrombin induced clot formation of plasma by a thrombin clotting time test. Scanning electron micrographs of the clot formed in the presence of vaccinia revealed a close packed fibrous structure lacking the cross-linked mesh-like pattern seen in a normal clot. Transmission electron micrographs showed an increase in the length and a close packing of the fibrin threads.

  11. Mice Lacking the ITIM-Containing Receptor G6b-B Exhibit Macrothrombocytopenia and Aberrant Platelet Function

    PubMed Central

    Mori, Jun; Bem, Danai; Finney, Brenda; Heising, Silke; Gissen, Paul; White, James G.; Berndt, Michael C.; Gardiner, Elizabeth E.; Nieswandt, Bernhard; Douglas, Michael R.; Campbell, Robert D.; Watson, Steve P.; Senis, Yotis A.

    2013-01-01

    Platelets are highly reactive cell fragments that adhere to exposed extracellular matrix (ECM) and prevent excessive blood loss by forming clots. Paradoxically, megakaryocytes, which produce platelets in the bone marrow, remain relatively refractory to the ECM-rich environment of the bone marrow despite having the same repertoire of receptors as platelets. These include the ITAM (immunoreceptor tyrosine–based activation motif)–containing collagen receptor complex, which consists of glycoprotein VI (GPVI) and the Fc receptor γ-chain, and the ITIM (immunoreceptor tyrosine–based inhibition motif)–containing receptor G6b-B. We showed that mice lacking G6b-B exhibited macrothrombocytopenia (reduced platelet numbers and the presence of enlarged platelets) and a susceptibility to bleeding as a result of aberrant platelet production and function. Platelet numbers were markedly reduced in G6b-B–deficient mice compared to those in wild-type mice because of increased platelet turnover. Furthermore, megakaryocytes in G6b-B–deficient mice showed enhanced metalloproteinase production, which led to increased shedding of cell-surface receptors, including GPVI and GPIba. In addition, G6b-B–deficient megakaryocytes exhibited reduced integrin-mediated functions and defective formation of proplatelets, the long filamentous projections from which platelets bud off. Together, these findings establish G6b-B as a major inhibitory receptor regulating megakaryocyte activation, function, and platelet production. PMID:23112346

  12. Platelet loss on exposure of citrated blood to various foreign surfaces.

    PubMed

    Perkins, H A; Rolfs, M R; Hymas, P G

    1975-01-01

    Citrated whole blood was rotated in tubes or closed loops of tubing and the percentage of platelets lost on exposure to the surface of the container was noted. Platelet loss in the presence of uncoated glass surfaces (mean loss 31%) was significantly less than in the presence of glass siliconed with two different reagents (82% and 86%). Platelets adhered to siliconed glass but not to uncoated glass. Other inert surfaces also resulted in a high degree of platelet loss: Teflon 90 per cent, silicone rubber 85 per cent, Parawax 84 per cent, polysytrene 82 per cent, polyethylene 79 per cent, polypropylene 60 per cent, and polycarbonate 58 per cent. One lot of polyvinyl chloride transfusion grade tubing resulted in only 2 per cent loss of platelets, but other lots varied between 35 and 84 per cent. Loss of platelets on exposure to the surface of plastic containers may have to be considered when evaluating new materials for preparation of blood components. PMID:804189

  13. Flow cytometric analysis of circulating platelet-monocyte aggregates in whole blood: methodological considerations.

    PubMed

    Harding, Scott A; Din, Jehangir N; Sarma, Jaydeep; Jessop, Alasdair; Weatherall, Mark; Fox, Keith A A; Newby, David E

    2007-08-01

    Platelet-monocyte aggregates are increasingly being used to quantify platelet activation. The variables that influence platelet-monocyte aggregates have not been well defined. We sought to determine the effect of blood collection, handling and processing techniques on detected levels of platelet-monocyte aggregates using a flow cytometric assay. Whole blood was labelled with anti-CD14-PE and anti-CD42a-FITC. Thereafter, samples were fixed and red cells lysed. Analysis was performed with the flow cytometer initially triggering on light scatter and then on FL-2 to identify CD14-PE positive monocytes. Platelet-monocyte aggregates were defined as monocytes positive for CD42a. The effect of collection, handling and processing techniques on this assay were assessed. Anticoagulation with heparin (20.1 +/- 2.0%), PPACK (16.8 +/- 1.9%), sodium citrate (12.3 +/- 1.6%) and EDTA (9.5 +/- 1.0%) resulted in markedly different levels of platelet-monocyte aggregation (P < 0.0001). Platelet-monocyte aggregation was higher in samples obtained from intravenous cannulae compared to those obtained by venepuncture (20.9 +/- 3.9% vs.13.8 +/- 2.4%, P = 0.03). For every 10 minutes of delay prior to processing platelet-monocyte aggregates increased by 2.8% (P = 0.0001) in PPACK anticoagulated blood and 1.7% (P = 0.01) in citrate anticoagulated blood. Erythrocyte lysis together with fixation does not affect platelet-monocyte aggregation. Platelet-monocyte aggregates remained stable over 24 hours when fixed and stored at 4 degrees C. Multiple handling and processing factors may affect platelet-monocyte aggregation. We recommend the measurement of platelet-monocyte aggregates on samples collected by direct venepuncture, using a direct thrombin inhibitor as the anticoagulant and minimising the time delay before sample fixation. PMID:17721630

  14. Desmopressin in vitro effects on platelet function, monitored with Multiplate, ROTEM and Sonoclot.

    PubMed

    Pearson, Kevin; Jensen, Hanna; Kander, Thomas; Schött, Ulf

    2016-07-01

    Background and aims The vasopressin analogue desmopressin has demonstrated efficacy in decreasing bleeding time by increasing the circulating levels of coagulation factor VIII and von Willebrand factor, but also by direct effects on platelets. Previous studies have demonstrated contrasting results regarding the effect of desmopressin on platelets in vitro. The aim of this study was to investigate the dose-response effects of in vitro desmopressin in whole blood. Our hypothesis was that desmopressin could increase platelet function in anticoagulated whole blood being stored up to 4 hours. Methods Desmopressin was administered with up to four different concentrations to venous whole blood, sampled with standard vacutainer tubes from 10 healthy volunteers after consent. Platelet function was analyzed with three different point-of-care techniques: Multiplate platelet aggregometry with adenosine diphosphate, collagen, thrombin receptor activating peptide-6, ristocetin and arachidonic acid agonists, tissue factor-activated thromboelastometry and Sonoclot glass bead viscoelastic coagulation tests at baseline and 4 hours later using different activator reagents. Results Thromboelastometry and Sonoclot did not show any significant change between baseline and 4 h later. A significant decrease in area under curve (AUC) could be seen with the Multiplate between baseline and after 4 h. Desmopressin did not improve any of these tests at baseline or during a 4 h storage and incubation period. Conclusion In vitro administered desmopressin could not increase normal platelet function or coagulation being measured with thromboelastometry and Sonoclot. Multiplate indicated decreased platelet aggregation over time, without any effect of in vitro added desmopressin. PMID:26923171

  15. Hemostatic Function, Survival, and Membrane Glycoprotein Changes in Young versus Old Rabbit Platelets

    PubMed Central

    Blajchman, Morris A.; Senyi, Andrew F.; Hirsh, Jack; Genton, Edward; George, James N.

    1981-01-01

    Although in vitro studies have demonstrated functional differences between young and old platelets, in vivo differences have not been precisely established. Therefore the in vivo hemostatic function of young and old platelets and the survival time have been examined in rabbits. The hemostatic function was measured by performing serial ear bleeding times in irradiation-induced thrombocytopenic rabbits. After irradiation with 930 rad the platelet count gradually diminished reaching a nadir (∼20 × 103/μl) at 10 d. The platelets present in the circulation, 7-10 d after irradiation, were considered old platelets, and the platelets present after recovery, 11-14 d postirradiation, young platelets. The measurement of platelet size was consistent with the hypothesis that platelets become smaller with age: the mean size was 3.84 μm3 for old platelets and 5.86 μm3 for young platelets. Regression analysis of the relationship between the bleeding time and the platelet count in 18 rabbits showed a significantly different slope for rabbits with predominantly old platelets compared with rabbits with predominantly young platelets (P < 0.001). Young platelets were more effective giving much shorter bleeding times than old platelets at comparable platelet counts. Survival times of young and old platelets were measured using platelets harvested on day 8 postirradiation (old platelets) and day 12 postirradiation (young platelets) that were labeled and then reinjected into normal recipient animals. The mean platelet survival time, calculated by gamma function, of old platelets was 28.8 h; of young platelets, 87.4 h; and of normally circulating heterogeneous platelets, (normal platelets) 53.0 h. Notably, the survival of old platelets was found to be exponential, and of young platelets, linear. Analysis of the membrane glycoproteins in young, old and normal platelets indicated that there was no qualitative difference amongst the young, normal, and old platelets. The relative

  16. Investigating the fluid mechanics behind red blood cell-induced lateral platelet motion

    NASA Astrophysics Data System (ADS)

    Crowl Erickson, Lindsay; Fogelson, Aaron

    2009-11-01

    Platelets play an essential role in blood clotting; they adhere to damaged tissue and release chemicals that activate other platelets. Yet in order to adhere, platelets must first come into contact with the injured vessel wall. Under arterial flow conditions, platelets have an enhanced concentration near blood vessel walls. This non-uniform cell distribution depends on the fluid dynamics of blood as a heterogeneous medium. We use a parallelized lattice Boltzmann-immersed boundary method to solve the flow dynamics of red cells and platelets in a periodic 2D vessel with no-slip boundary conditions. Red cells are treated as biconcave immersed boundary objects with isotropic Skalak membrane tension and an internal viscosity five times that of the surrounding plasma. Using this method we analyze the influence of shear rate, hematocrit, and red cell membrane properties on lateral platelet motion. We find that the effective diffusion of platelets is significantly lower near the vessel wall compared to the center of the vessel. Insight gained from this work could lead to significant improvements to current models for platelet adhesion where the presence of red blood cells is neglected due to computational intensity.

  17. The active metabolite of prasugrel inhibits ADP-stimulated thrombo-inflammatory markers of platelet activation: Influence of other blood cells, calcium, and aspirin.

    PubMed

    Frelinger, Andrew L; Jakubowski, Joseph A; Li, Youfu; Barnard, Marc R; Fox, Marsha L; Linden, Matthew D; Sugidachi, Atsuhiro; Winters, Kenneth J; Furman, Mark I; Michelson, Alan D

    2007-07-01

    The novel thienopyridine prodrug prasugrel, a platelet P2Y(12) ADP receptor antagonist, requires in vivo metabolism for activity. Although pharmacological data have been collected on the effects of prasugrel on platelet aggregation, there are few data on the direct effects of the prasugrel's active metabolite, R-138727, on other aspects of platelet function. Here we examined the effects of R-138727 on thrombo-inflammatory markers of platelet activation, and the possible modulatory effects of other blood cells, calcium, and aspirin. Blood (PPACK or citrate anticoagulated) from healthy donors pre- and post-aspirin was incubated with R-138727 and the response to ADP assessed in whole blood or platelet-rich plasma (PRP) by aggregometry and flow cytometric analysis of leukocyte-platelet aggregates, platelet surface P-selectin, and GPIIb-IIIa activation. Low-micromolar concentrations of R-138727 resulted in a rapid and consistent inhibition of these ADP-stimulated thrombo-inflammatory markers. These rapid kinetics required physiological calcium levels, but were largely unaffected by aspirin. Lower IC(50) values in whole blood relative to PRP suggested that other blood cells affect ADP-induced platelet activation and hence the net inhibition by R-138727. R-138727 did not inhibit P2Y(12)-mediated ADP-induced shape change, even at concentrations that completely inhibited platelet aggregation, confirming the specificity of R-138727 for P2Y(12). In conclusion, R-138727, the active metabolite of prasugrel, results in rapid, potent, consistent, and selective inhibition of P2Y(12)-mediated up-regulation of thrombo-inflammatory markers of platelet activation. This inhibition is enhanced in the presence other blood cells and calcium, but not aspirin. PMID:17598013

  18. Pathogen Inactivation of Platelet and Plasma Blood Components for Transfusion Using the INTERCEPT Blood System™

    PubMed Central

    Irsch, Johannes; Lin, Lily

    2011-01-01

    Summary Background The transmission of pathogens via blood transfusion is still a major threat. Expert conferences established the need for a pro-active approach and concluded that the introduction of a pathogen inactivation/reduction technology requires a thorough safety profile, a comprehensive pre-clinical and clinical development and an ongoing hemovigilance program. Material and Methods The INTERCEPT Blood System utilizes amotosalen and UVA light and enables for the treatment of platelets and plasma in the same device. Preclinical studies of pathogen inactivation and toxicology and a thorough program of clinical studies have been conducted and an active he-movigilance-program established. Results INTERCEPT shows robust efficacy of inactivation for viruses, bacteria (including spirochetes), protozoa and leukocytes as well as large safety margins. Furthermore, it integrates well into routine blood center operations. The clinical study program demonstrates the successful use for very diverse patient groups. The hemovigilance program shows safety and tolerability in routine use. Approximately 700,000 INTERCEPT-treated products have been transfused worldwide. The system is in clinical use since class III CE-mark registration in 2002. The safety and efficacy has been shown in routine use and during an epidemic. Conclusion The INTERCEPT Blood System for platelets and plasma offers enhanced safety for the patient and protection against transfusion-transmitted infections. PMID:21779203

  19. Regional platelet concentration in blood flow through capillary tubes.

    PubMed

    Corattiyl, V; Eckstein, E C

    1986-09-01

    Platelet concentration was measured in samples from the various components of a bloodflow circuit, including the reservoir, the tube (with i.d. between 50 and 210 micron), and the discharge. The tube sample was collected by halting the flow and then flushing out a length of tube; thus, this sample collected equally from all radial locations. As the discharge sample was well mixed, it reflected the velocity field in the tube. Each reservoir sample was a traditional bulk collection. To ensure that the results represented the physical effects of flow on regional platelet concentration and could be interpreted with simple mass balance relationships, strong anticoagulation (sodium citrate and heparin) and platelet inhibition (prostaglandin E1) were used. Results for all tube diameters and for reservoir hematocrits from 5.5 to 77% and wall shear rates from 80 to 8000 sec-1 show that tubular platelet concentration is greater than reservoir or discharge platelet concentrations, which are equal. For platelet-rich plasma the tubular platelet concentration is decreased compared to the reservoir or discharge values. Mass balances show that the elevated tubular platelet concentration is due to an excess of platelets in radial locations with below average speeds; coupled with the need for red cells, this suggests that excess platelets have a near-wall location. Nonparametric statistical tests show that wall shear rate is a significant variable at a 0.05 confidence level; inner diameter is not found to be a significant variable, probably because of the limited diameter range studied and the experimental errors involved in determining platelet concentrations. PMID:3762431

  20. Relationship between the Increased Haemostatic Properties of Blood Platelets and Oxidative Stress Level in Multiple Sclerosis Patients with the Secondary Progressive Stage

    PubMed Central

    Bijak, Michał; Miller, Elżbieta; Miller, Sergiusz

    2015-01-01

    Multiple sclerosis (MS) is the autoimmune disease of the central nervous system with complex pathogenesis, different clinical courses and recurrent neurological relapses and/or progression. Despite various scientific papers that focused on early stage of MS, our study targets selective group of late stage secondary progressive MS patients. The presented work is concerned with the reactivity of blood platelets in primary hemostasis in SP MS patients. 50 SP MS patients and 50 healthy volunteers (never diagnosed with MS or other chronic diseases) were examined to evaluate the biological activity of blood platelets (adhesion, aggregation), especially their response to the most important physiological agonists (thrombin, ADP, and collagen) and the effect of oxidative stress on platelet activity. We found that the blood platelets from SP MS patients were significantly more sensitive to all used agonists in comparison with control group. Moreover, the platelet hemostatic function was advanced in patients suffering from SP MS and positively correlated with increased production of O2−∙ in these cells, as well as with Expanded Disability Status Scale. We postulate that the increased oxidative stress in blood platelets in SP MS may be primarily responsible for the altered haemostatic properties of blood platelets. PMID:26064417

  1. How do the full-generation poly(amido)amine (PAMAM) dendrimers activate blood platelets? Activation of circulating platelets and formation of "fibrinogen aggregates" in the presence of polycations.

    PubMed

    Watala, Cezary; Karolczak, Kamil; Kassassir, Hassan; Talar, Marcin; Przygodzki, Tomasz; Maczynska, Katarzyna; Labieniec-Watala, Magdalena

    2016-04-30

    Direct use of poly(amido)amine (PAMAM) dendrimers as drugs may be limited, due to uncertain (cyto)toxicity. Peripheral blood components, which constitute the first line of a contact with administered pharmaceuticals, may become vastly affected by PAMAM dendrimers. The aim of this study was to explore how PAMAMs' polycationicity might affect blood platelet activation and reactivity, and thus trigger various haemostatic events. We monitored blood platelet reactivity in rats with experimental diabetes upon a long-term administration of the unmodified PAMAM dendrimers. In parallel, the effects on blood flow in a systemic circulation was recorded intravitally in mice administered with PAMAM G2, G3 or G4. Compounding was the in vitro approach to monitor the impact of PAMAM dendrimers on blood platelet activation and reactivity and on selected haemostatic and protein conformation parameters. We demonstrated the activating effects of polycations on blood platelets. Some diversity of the revealed outcomes considerably depended on the used approach and the particular technique employed to monitor blood platelet function. We discovered undesirable impact of plain PAMAM dendrimers on primary haemostasis and their prothrombotic influence. We emphasize the need of a more profound verifying of all the promising findings collected for PAMAMs with the use of well-designed in vivo preclinical studies. PMID:26319628

  2. Utility of the ISTH bleeding assessment tool in predicting platelet defects in participants with suspected inherited platelet function disorders

    PubMed Central

    Lowe, G C; Lordkipanidzé, M; Watson on behalf of the uk gapp study group, S P

    2013-01-01

    Background The ISTH bleeding assessment tool (ISTH-BAT) was developed to record bleeding symptoms and to aid diagnosis in patients with a possible bleeding disorder. Objectives To investigate the utility of the ISTH-BAT in predicting functional defects in platelet activation in participants with suspected inherited platelet function disorders. Patients/Methods Participants with clinical evidence of excessive bleeding and suspected inherited platelet function disorders and healthy volunteers were recruited to the Genotyping and Phenotyping of Platelets study (GAPP; ISRCTN 77951167). The ISTH-BAT questionnaire was applied by a trained investigator prior to lumiaggregometry. Results One hundred participants were included (79 with suspected inherited platelet function disorders, and 21 healthy volunteers). The ISTH-BAT score in participants with suspected inherited platelet function disorders (median 12; interquartile range [IQR] 8–16) was significantly higher than in healthy volunteers (median 0; IQR 0–0). There was no difference between participants with suspected inherited platelet function disorders with a platelet defect detected by lumiaggregometry (median 11; IQR 8–16) and those with normal platelet function (median 12; IQR 8–14) (P > 0.05). The ISTH-BAT score was not associated with a demonstrable platelet defect on platelet function testing (area under the receiver operating characteristic curve = 0.501 [95% confidence interval 0.372–0.630, P = 0.98] and odds ratio 1.01 [95% confidence interval 0.93–1.09, P = 0.91]). Conclusions The ISTH-BAT is a powerful tool for documenting lifelong bleeding history. However, the score obtained is not predictive of the presence of a platelet defect on lumiaggregometry in patients with suspected inherited platelet function disorders. PMID:23809206

  3. Platelets and coronary artery disease: Interactions with the blood vessel wall and cardiovascular devices.

    PubMed

    Reinthaler, Markus; Braune, Steffen; Lendlein, Andreas; Landmesser, Ulf; Jung, Friedrich

    2016-01-01

    In view of the rare presence of studies concerning platelet function as risk factor in atherosclerotic patients, processes underlying thromboembolic events are reviewed in this paper. The morphology and the structural organization-membrane receptors, the open canalicular and dense tubular systems, the cytoskeleton, mitochondria, granules, lysosomes, and peroxisomes-of platelets are described. Platelet function under physiological conditions in atherosclerosis and after implantation of cardiovascular devices is summarized. PMID:27277200

  4. Era of blood component therapy: time for mandatory pre-donation platelet count for maximizing donor safety and optimizing quality of platelets.

    PubMed

    Das, Sudipta Sekhar; Zaman, R U; Biswas, Dipak

    2013-12-01

    Blood bank regulatory agencies including the Drug and Cosmetics Act (DCA) of India do not mandate a predonation platelet count in whole blood donation. Mandating such practice will definitely optimize the quality of random donor platelets (RDP) in terms of platelet yield and patient therapeutic benefit. We observed poor platelet yield in RDP concentrates prepared at our center with a significant number not meeting the DCA guideline of ≥ 4.5 × 10(10) per bag processed from 450 ml of whole blood. Therefore we planned this study to evaluate the pre-donation hematological values in our blood donor population and effect of these values on the quality of platelet concentrates. The prospective study included 221 blood donors eligible for donating 450 ml of whole blood (WB). Following the departmental standard operating procedure (SOP) RDPs were prepared using the 'Top & Bottom' quadruple bag system and automated component extractor. Quality of RDP was assessed as per departmental protocol. All results were recorded and subsequently transcribed to SPSS working sheet. A significant (p<0.001) decrement of donor blood counts has been observed after WB donation. Mean donor Hb and platelets reduced by 0.72 g/dl and 22.1 × 10(6)/ml respectively. Quality of RDPs in terms of platelet yield was significantly better (p<0.001) when donor platelet count was >200 × 10(6)/ml. Although platelet yield significantly correlated with the donor platelet count however quality of RDPs in terms of red cell contamination showed no correlation with the donor hematocrit. Platelet yield in random donor platelets is a concern in Eastern India. A platelet yield of 4.5 × 10(10) per bag as mandated by the DCA of India was only achieved when the donor platelet count was >200 × 10(6)/ml. Posttransfusion platelet recovery (PPR) was unsatisfactory in the transfused patient. Introduction of pre-donation platelet count in whole blood donation will maximize donor safety and optimize patient platelet

  5. Amikacin can be added to blood to reduce the fall in platelet count.

    PubMed

    Zhou, Xiaomian; Wu, Xiaoli; Deng, Weixiong; Li, Jieqiu; Luo, Wenshen

    2011-10-01

    Our objective was to develop an effective method to prevent the fall in platelet count for patients with anticoagulant-dependent (AD) pseudothrombocytopenia, a spurious phenomenon due to anticoagulant-induced aggregation of platelets. We report a case of insidious multianticoagulant-dependent pseudothrombocytopenia in which AD pseudothrombocytopenia may be caused by 4 anticoagulants, eg, EDTA, sodium citrate, heparin, and sodium fluoride (NaF). Multianticoagulant-dependent pseudothrombocytopenia was confirmed by finding clumped platelets on microscopic evaluation in 4 anticoagulated blood samples. With this case, we tried a variety of reagents, including aminoglycosides, eg, gentamicin and amikacin, vitamin B(6), and aminophylline to inhibit pseudothrombocytopenia. Except for amikacin, all reagents failed to prevent pseudothrombocytopenia. Microscopic examination of K(2)-EDTA-, heparin-, sodium citrate-, and NaF-anticoagulated blood samples showed massive platelet clumping, but no aggregate was seen in the anticoagulated blood with amikacin. When amikacin was added within 1 hour after blood sample withdrawal, platelet, WBC, and RBC counts and hemoglobin level, mean corpuscular volume, and mean platelet volume remained unchanged for up to 4 hours at room temperature. These findings suggest that amikacin could inhibit and dissociate pseudo platelet aggregation in multianticoagulant-dependent pseudothrombocytopenia and EDTA-induced pseudothrombocytopenia. PMID:21917689

  6. Activated Platelets in Heparinized Shed Blood: The “Second-Hit” of Acute Lung Injury in Trauma/Hemorrhagic Shock Models

    PubMed Central

    Harr, Jeffrey N.; Moore, Ernest E.; Wohlauer, Max V.; Fragoso, Miguel; Gamboni, Fabia; Liang, Xiayuan; Banerjee, Anirban; Silliman, Christopher C.

    2011-01-01

    Background The return of heparinized shed blood in trauma/hemorrhagic shock (T/HS) models remains controversial due to potential anti-inflammatory properties. Although ubiquitous as an anticoagulant, heparin is ineffective on cellular coagulation as an antithrombotic agent. Therefore, we hypothesized that returning heparinized shed blood would paradoxically enhance ALI following T/HS due to the infusion of activated platelets. Methods Sprague-Dawley rats, anesthetized with pentobarbital, underwent laparotomy and hemorrhage-induced shock (MAP of 30 mmHg × 45 min). Animals were resuscitated with a combination of normal saline (NS) and returned shed blood. Shed blood was collected in either 80U/kg of heparin, 800U/kgof heparin, citrate, or diluted 1:8 with NS. An additional group of animals were pretreated with a platelet P2Y12 receptor antagonist (clopidogrel) prior to T/HS. BAL, lung MPO assays, pulmonary immunofluorescence, and blood smears were conducted. Results BAL protein increased in animals resuscitated with heparinized shed blood (p<0.0001). Blood smears and platelet function assays revealed platelet aggregates and increased platelet activation. Animals pretreated with a platelet P2Y12 receptor antagonist were protected from post-injury ALI (p<0.0001). Animals with return of shed blood had increased pulmonary PMN sequestration (p<0.0001). Pulmonary immunofluorescence demonstrated microthrombi only in the T/HS group receiving heparinized shed blood (p<0.0001). Conclusion The return of heparinized shed blood functions as a “second-hit” to enhance ALI, with activated platelets propagating microthrombi and pulmonary PMN recruitment. PMID:21841533

  7. Developmental endothelial locus-1 modulates platelet-monocyte interactions and instant blood-mediated inflammatory reaction in islet transplantation.

    PubMed

    Kourtzelis, Ioannis; Kotlabova, Klara; Lim, Jong-Hyung; Mitroulis, Ioannis; Ferreira, Anaisa; Chen, Lan-Sun; Gercken, Bettina; Steffen, Anja; Kemter, Elisabeth; Klotzsche-von Ameln, Anne; Waskow, Claudia; Hosur, Kavita; Chatzigeorgiou, Antonios; Ludwig, Barbara; Wolf, Eckhard; Hajishengallis, George; Chavakis, Triantafyllos

    2016-04-01

    Platelet-monocyte interactions are strongly implicated in thrombo-inflammatory injury by actively contributing to intravascular inflammation, leukocyte recruitment to inflamed sites, and the amplification of the procoagulant response. Instant blood-mediated inflammatory reaction (IBMIR) represents thrombo-inflammatory injury elicited upon pancreatic islet transplantation (islet-Tx), thereby dramatically affecting transplant survival and function. Developmental endothelial locus-1 (Del-1) is a functionally versatile endothelial cell-derived homeostatic factor with anti-inflammatory properties, but its potential role in IBMIR has not been previously addressed. Here, we establish Del-1 as a novel inhibitor of IBMIR using a whole blood-islet model and a syngeneic murine transplantation model. Indeed, Del-1 pre-treatment of blood before addition of islets diminished coagulation activation and islet damage as assessed by C-peptide release. Consistently, intraportal islet-Tx in transgenic mice with endothelial cell-specific overexpression of Del-1 resulted in a marked decrease of monocytes and platelet-monocyte aggregates in the transplanted tissues, relative to those in wild-type recipients. Mechanistically, Del-1 decreased platelet-monocyte aggregate formation, by specifically blocking the interaction between monocyte Mac-1-integrin and platelet GPIb. Our findings reveal a hitherto unknown role of Del-1 in the regulation of platelet-monocyte interplay and the subsequent heterotypic aggregate formation in the context of IBMIR. Therefore, Del-1 may represent a novel approach to prevent or mitigate the adverse reactions mediated through thrombo-inflammatory pathways in islet-Tx and perhaps other inflammatory disorders involving platelet-leukocyte aggregate formation. PMID:26676803

  8. Microfluidic assessment of functional culture-derived platelets in human thrombi under flow.

    PubMed

    Kamat, Viraj; Muthard, Ryan W; Li, Ruizhi; Diamond, Scott L

    2015-10-01

    Despite their clinical significance, human platelets are not amenable to genetic manipulation, thus forcing a reliance on mouse models. Culture-derived platelets (CDPs) from human peripheral blood CD34(+) cells can be genetically altered and may eventually be used for transfusions. By use of microfluidics, the time-dependent incorporation of CD41(+)CD42(+) CDPs into clots was measured using only 54,000 CDPs doped into 27 μL of human whole blood perfused over collagen at a wall shear rate of 100 sec(-1). With the use of fluorescence-labeled human platelets (instead of CDPs) doped between 0.25% and 2% of total platelets, incorporation was highly quantitative and allowed monitoring of the anti-αIIbβ3 antagonism that occurred after collagen adhesion. CDPs were only 15% as efficient as human platelets in their incorporation into human thrombi under flow, although both cell types were equally antagonized by αIIbβ3 inhibition. Transient transfection allowed the monitoring of GFP(+) human CDP incorporation into clots. This assay quantifies genetically altered CDP function under flow. PMID:26145051

  9. Identification of platelet function defects by multi-parameter assessment of thrombus formation

    PubMed Central

    de Witt, Susanne M.; Swieringa, Frauke; Cavill, Rachel; Lamers, Moniek M. E.; van Kruchten, Roger; Mastenbroek, Tom; Baaten, Constance; Coort, Susan; Pugh, Nicholas; Schulz, Ansgar; Scharrer, Inge; Jurk, Kerstin; Zieger, Barbara; Clemetson, Kenneth J.; Farndale, Richard W.; Heemskerk, Johan W. M.; Cosemans, Judith M.E.M.

    2014-01-01

    Assays measuring platelet aggregation (thrombus formation) at arterial shear rate mostly use collagen as only platelet-adhesive surface. Here we report a multi-surface and multi-parameter flow assay to characterize thrombus formation in whole blood from healthy subjects and patients with platelet function deficiencies. A systematic comparison is made of 52 adhesive surfaces with components activating the main platelet-adhesive receptors, and of eight output parameters reflecting distinct stages of thrombus formation. Three types of thrombus formation can be identified with a predicted hierarchy of the following receptors: glycoprotein (GP)VI, C-type lectin-like receptor-2 (CLEC-2)>GPIb>α6β1, αIIbβ3>α2β1>CD36, α5β1, αvβ3. Application with patient blood reveals distinct abnormalities in thrombus formation in patients with severe combined immune deficiency, Glanzmann’s thrombasthenia, Hermansky–Pudlak syndrome, May–Hegglin anomaly or grey platelet syndrome. We suggest this test may be useful for the diagnosis of patients with suspected bleeding disorders or a pro-thrombotic tendency. PMID:25027852

  10. Interaction of inorganic nanoparticles of lunar soil simulant with blood platelets

    NASA Astrophysics Data System (ADS)

    Borisova, Tatiana; Kasatkina, Ludmila; Krisanova, Natalia; Sivko, Roman; Borisov, Arseniy; Slenzka, Klaus

    Blood platelets play a central role in the physiology of primary hemostasis and in the patholog-ical processes of arterial thrombosis. Also, blood platelets contain neuronal high-affinity Na+-dependent glutamate transporters (EAAT 1 -3) and are able to uptake glutamate, thereby playing possible physiological role in extracellular glutamate homeostasis in the mammalian CNS as an additional powerful target for excessive neurotoxic glutamate accumulation and storage. The health effects of lunar soil exposure are almost completely unknown, whereas the observations suggest that it can be deleterious to human physiology. It is important that the components of lunar soil may be internalized with lipid fractions of the lung epithelium, which in turn may help ions to overcome the blood-brain barrier. The study focused on the effects of JSC-1a Lunar Soil Simulant (LSS) (Orbital Technologies Corporation, Madison, USA) on platelets isolated from rabbit blood. We revealed that platelets were not indifferent to the expo-sure to LSS. Flow cytometric analysis showed that the incubation of platelets with LSS resulted in an upper shift of platelet spot in histograms presenting cell size (FS) and granularity (SS) as x and y coordinates, thereby demonstrating apparent increase in platelet granularity. Analysis of control platelet preparation did not reveal the alterations in platelet size and granularity during the same incubation period. LSS scatter per se did not cover area of platelet prepara-tion in histogram. Using Zetasizer Nanosystem (Malvern Instruments) with helium-neon laser for dynamic light scattering (DLS), the platelet size before and after the addition of LSS was measured. We have found the increase in the mean size of the population of platelets from 2.45 ±0.09 µm in control to 3.0 ± 0.25 µm in the presence of LSS. Thus, we report that inorganic nanoparticles of LSS bind to blood platelets and this fact may have considerable harmful conse-quences to human

  11. Catabolism of exogenously supplied thymidine to thymine and dihydrothymine by platelets in human peripheral blood

    SciTech Connect

    Pero, R.W.; Johnson, D.; Olsson, A.

    1984-11-01

    The interference of platelets with the estimation of unscheduled DNA synthesis in human peripheral mononuclear leukocytes following genotoxic exposure was studied. A 96% reduction in the unscheduled DNA synthesis value was achieved by incubating (/sup 3/H)thymidine with platelet-rich plasma for 5 hr at 37 degrees. Using radioactive thymine-containing compounds, together with quantitative analyses based on thin-layer and ion-exchange chromatographies, we have shown that thymidine was converted to thymine which, in turn, was converted to dihydrothymine in platelet-rich plasma. The enzymes responsible were separated from platelet lysates by gel filtration and were identified as thymidine phosphorylase and dihydrothymine dehydrogenase. The phosphorylase reversibly catalyzed the formation of thymine from thymidine and converted bromodeoxyuridine to bromouracil. The dehydrogenase reversibly catalyzed the interconversion of thymine and dihydrothymine in a reaction dependent on NADP(H), and it was inhibited by diazouracil and by thymine. Nearly all the thymidine-catabolizing activity found in whole blood samples supplied exogenously with thymidine was accounted for by the platelets. Since most genetic toxicological tests that use blood samples do not involve removing platelets from the blood cell cultures, then it is concluded that precautions should be taken in the future to determine the influence of platelets on these test systems. This is particularly true for methods dependent on thymidine pulses such as unscheduled DNA synthesis, or those dependent on bromodeoxyuridine, such as sister chromatid exchanges, since this nucleoside is also a substrate for thymidine phosphorylase.

  12. Inhibitory effects of Cyperus digitatus extract on human platelet function in vitro.

    PubMed

    Fuentes, Eduardo; Forero-Doria, Oscar; Alarcón, Marcelo; Palomo, Iván

    2015-01-01

    The purpose of this research was to investigate the mechanisms of antiplatelet action of Cyperus digitatus. The antiplatelet action of C. digitatus was studied on platelet function: secretion, adhesion, aggregation, and sCD40L release. The platelet ATP secretion and aggregation were significantly inhibited by CDA (ethyl acetate extract) at 0.1 mg/ml and after the incubation of whole blood with CDA, the platelet coverage was inhibited by 96 ± 3% (p < 0.001). At the same concentration, CDA significantly decreased sCD40L levels. The mechanism of antiplatelet action of CDA could be by NF-κB inhibition and that is cAMP independent. In conclusion, C. digitatus extract may serve as a new source of antiplatelet agents for food and nutraceutical applications. PMID:25548968

  13. Effect of Red Blood Cells on Platelet Activation and Thrombus Formation in Tortuous Arterioles

    PubMed Central

    Chesnutt, Jennifer K. W.; Han, Hai-Chao

    2013-01-01

    Thrombosis is a major contributor to cardiovascular disease, which can lead to myocardial infarction and stroke. Thrombosis may form in tortuous microvessels, which are often seen throughout the human body, but the microscale mechanisms and processes are not well understood. In straight vessels, the presence of red blood cells (RBCs) is known to push platelets toward walls, which may affect platelet aggregation and thrombus formation. However in tortuous vessels, the effects of RBC interactions with platelets in thrombosis are largely unknown. Accordingly, the objective of this work was to determine the physical effects of RBCs, platelet size, and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A discrete element computational model was used to simulate the transport, collision, adhesion, aggregation, and shear-induced platelet activation of hundreds of individual platelets and RBCs in thrombus formation in tortuous arterioles. Results showed that high shear stress near the inner sides of curved arteriole walls activated platelets to initiate thrombosis. RBCs initially promoted platelet activation, but then collisions of RBCs with mural thrombi reduced the amount of mural thrombus and the size of emboli. In the absence of RBCs, mural thrombus mass was smaller in a highly tortuous arteriole compared to a less tortuous arteriole. In the presence of RBCs however, mural thrombus mass was larger in the highly tortuous arteriole compared to the less tortuous arteriole. As well, smaller platelet size yielded less mural thrombus mass and smaller emboli, either with or without RBCs. This study shed light on microscopic interactions of RBCs and platelets in tortuous microvessels, which have implications in various pathologies associated with thrombosis and bleeding. PMID:25022613

  14. Protein kinase C translocation in human blood platelets

    SciTech Connect

    Wang, Hoauyan; Friedman, E. )

    1990-01-01

    Protein kinase C (PKC) activity and translocation in response to the phorbol ester, phorbol 12-myristate, 13-acetate (PMA), serotonin (5-HT) and thrombin was assessed in human platelets. Stimulation with PMA and 5-HT for 10 minutes or thrombin for 1 minute elicited platelet PKC translocation from cytosol to membrane. The catecholamines, norepinephrine or epinephrine at 10 {mu}M concentrations did not induce redistribution of platelet PKC. Serotonin and the specific 5-HT{sub 2} receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane (DOI) but not the 5-HT{sub 1A} or 5-HT{sub 1B} agonists, ({plus minus}) 8-hydroxy-dipropylamino-tetralin (8-OH-DPAT) or 5-methoxy-3-3-(1,2,3,6-tetrahydro-4-pyridin) 1H-indole succinate (RU 24969) induced dose-dependent PKC translocations. Serotonin-evoked PKC translocation was blocked by selective 5-HT{sub 2} receptor antagonists, ketanserin and spiroperidol. These results suggest that, in human platelets, PMA, thrombin and 5-HT can elicit PKC translocation from cytosol to membrane. Serotonin-induced PKC translocation in platelets is mediated via 5-HT{sub 2} receptors.

  15. Red cabbage anthocyanins as inhibitors of lipopolysaccharide-induced oxidative stress in blood platelets.

    PubMed

    Saluk, Joanna; Bijak, Michal; Posmyk, Malgorzata M; Zbikowska, Halina M

    2015-09-01

    LPS is a Gram-negative bacteria endotoxin, which is an important pro-inflammatory agent. Blood platelets take part both in inflammatory processes and in pathogenesis of septic shock following accumulation of LPS. As a platelet agonist LPS causes the intraplatelet overproduction of ROS/RNS that are responsible for adverse modifications in the structure of platelet compounds being associated with a development of platelet-dependent diseases. Existing evidence suggests that anthocyanins (ATH) are able to protect the circulatory system. The antioxidative properties of ATH are believed to be mainly responsible for their positive health effects. The main goal of the present in vitro study was to investigate the potential protective properties of red cabbage ATH against oxidative damage induced by LPS in blood platelets. Exposure of platelets to LPS resulted in carbonyl group increase, 3-nitrotyrosine formation, lipid peroxidation and O2(•-) generation. We have shown that ATH extract effectively decreased oxidative stress induced by LPSs. The in silico analysis demonstrated that both cyanin and LPS were located at the same region of human TLR4-MD-2 complex. Our findings suggest that there could be two-way ATH platelet protection mechanism, by their antioxidant properties and directly by binding with TLRs. PMID:26208857

  16. Platelet function in dogs with bacterial infections and leishmaniasis.

    PubMed

    Abid, Monia; Kalbantner, Kerstin; Mischke, Reinhard

    2015-01-01

    The objective of this study was to examine the influence of bacterial infections or leishmaniasis on primary haemostasis in dogs. Capillary bleeding time, automatic platelet function analysis (PFA-100), turbidimetric platelet aggregation, impedance aggregometry, platelet count and, in addition, the haematocrit were investigated in 25 dogs with bacterial infections or leishmaniasis . Results of these diseased dogs were compared to the control group and additionally classified into two subgroups based on criteria of systemic inflammatory response syndrome (SIRS) (groups "SIRS" and "Non-SIRS"). Dogs with infections had a significantly prolonged closure time of the PFA-100 using both cartridges (e. g., collagen/ADP: 83 [55-301] vs. 65 [47-99 s; median [minimum-maximum]; p < 0.0001), a significant decrease in maximal aggregation of the turbidimetric aggregometry (e. g., ADP-induced: 45.2 ± 26.8 vs. 67.3 ± 21.8%; mean ± SD; P = 0.003), a significant increase of collagen-induced impedance aggregometry and a significant suppression of arachidonic acid-induced impedance aggregometry. An enhanced collagen-induced impedance aggregation was the only significant difference between subgroups "SIRS"and "Non-SIRS". In conclusion, although individual tests indicate enhanced platelet aggregation, most of the in vitro tests revealed a normal to moderately reduced functionality. The reduced aggregabiity may partly indicate preactivation of platelets. PMID:26281441

  17. Modeling HIV-1 Induced Neuroinflammation in Mice: Role of Platelets in Mediating Blood-Brain Barrier Dysfunction

    PubMed Central

    Jones, Letitia D.; Jackson, Joseph W.; Maggirwar, Sanjay B.

    2016-01-01

    The number of HIV-1 positive individuals developing some form of HIV-associated neurocognitive disorder (HAND) is increasing. In these individuals, the integrity of the blood-brain barrier (BBB) is compromised due to an increase in exposure to pro-inflammatory mediators, viral proteins, and virus released from infected cells. It has been shown that soluble CD40L (sCD40L) is released upon platelet activation and is an important mediator of the pathogenesis of HAND but the underlying mechanisms are unclear, emphasizing the need of an effective animal model. Here, we have utilized a novel animal model in which wild-type (WT) mice were infected with EcoHIV; a derivative of HIV-1 that contains a substitution of envelope protein gp120 with that of gp80 derived from murine leukemia virus-1 (MuLV-1). As early as two-weeks post-infection, EcoHIV led to increased permeability of the BBB associated with decreased expression of tight junction protein claudin-5, in CD40L and platelet activation-dependent manner. Treatment with an antiplatelet drug, eptifibatide, in EcoHIV-infected mice normalized BBB function, sCD40L release and platelet activity, thus implicating platelet activation and platelet-derived CD40L in virally induced BBB dysfunction. Our results also validate and underscore the importance of EcoHIV infection mouse model as a tool to explore therapeutic targets for HAND. PMID:26986758

  18. Platelet function during cardiopulmonary bypass using multiple electrode aggregometry: comparison of centrifugal and roller pumps.

    PubMed

    Kehara, Hiromu; Takano, Tamaki; Ohashi, Noburo; Terasaki, Takamitsu; Amano, Jun

    2014-11-01

    Blood trauma may be lower with centrifugal pumps (CPs) than with roller pumps (RPs) during cardiopulmonary bypass (CPB), because, unlike RPs, CPs do not compress the tubing, and shear stress is considered lower in CPs than in RPs. However, relative platelet function remains unclear. Using multiple electrode aggregometry (MEA), we compared platelet function with CP and RP. Ten swine underwent CPB for 3 h, with five weaned off using CP and five using RP. Platelet function was measured using MEA, as were hemoglobin concentration and platelet count, before sternotomy, after heparin infusion, 30 min and 3 h after starting CPB, after protamine infusion, and 60 min after stopping CPB. Platelet activation was initiated with adenosine diphosphate (ADP), arachidonic acid (AA), and thrombin receptor-activating protein 6 (TRAP). Fibrinogen, platelet factor 4 (PF4), and β-thromboglobin (β-TG) concentrations were measured before sternotomy and 60 min after stopping CPB. In the CP group and using ADP, aggregation was significantly reduced 30 min (P = 0.019) and 3 h (P = 0.027) after starting CPB, recovering to baseline 60 min after CPB was stopped. In the RP group, aggregation was significantly decreased 30 min (P = 0.007) and 3 h (P = 0.003) after starting CPB and after protamine administration (P = 0.028). With AA, aggregation significantly decreased 30 min after starting CPB in both the CP (P = 0.012) and RP (P = 0.016) groups, slightly increasing 3 h after starting CPB and after protamine infusion, and recovering to baseline 60 min after CPB cessation. With TRAP, aggregation in the CP and RP groups decreased 30 min after starting the pump, although changes were not significant; aggregation gradually recovered after 3 h and returned to baseline 60 min after the pumps were stopped. There were no significant differences at all sampling points of MEA. In both groups, fibrinogen, PF4, and β-TG concentrations were similar 60 min after pump cessation and before sternotomy

  19. Identification of D/sub 1/-like dopamine receptors on human blood platelets

    SciTech Connect

    De Keyser, J.; De Waele, M.; Convents, A.; Ebinger, G.; Vauquelin, G.

    1988-01-01

    Dopamine is able to inhibit the epinephrine-induced aggregation of human blood platelets, but the mechanism of action has not been elucidated. In this study the authors report that membranes from human blood platelets possess high affinity, saturable and stereoselective binding sites for the D/sub 1/ dopamine receptor antagonist (/sup 3/H)SCH 23390. (/sup 3/H)SCH 23390 appeared to label a single class of binding sites with a B/sub max/ of 18.6 +- 1.6 fmolmg protein and a K/sub D/ of 0.8 nM. The potencies of different dopaminergic antagonists and agonists in displacing (/sup 3/H)SCH 23390 from blood platelet membranes were similar to those obtained for striatal membranes. Unlike the classically defined D/sub 1/ receptors, e.g. those in striatum, the D/sub 1/ receptor sites on platelets appeared no to be coupled to the adenylate cyclase system, hence the term D/sub 1/-like. The D/sub 1/ agonist SKF 38393 was more potent than dopamine in inhibiting platelet aggregation induced by epinephrine, and the effects of dopamine and SKF 38393 were prevented by SCH 23390. These results suggest that the inhibitory action of dopamine on the epinephrine-induced platelet aggregation is mediated through these D/sub 1/-like receptors

  20. Perilla oil improves blood flow through inhibition of platelet aggregation and thrombus formation

    PubMed Central

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang-Sei; Lee, Sung-Pyo; Kang, Myung-Hwa; Choi, Ehn-Kyoung

    2014-01-01

    The inhibitory effects of perilla oil on the platelet aggregation in vitro and thrombosis in vivo were investigated in comparison with aspirin, a well-known blood flow enhancer. Rabbit platelet-rich plasma was incubated with perilla oil and aggregation inducers collagen or thrombin, and the platelet aggregation rate was analyzed. Perilla oil significantly inhibited both the collagen- and thrombin-induced platelet aggregations, in which the thromboxane B2 formation from collagen-activated platelets were reduced in a concentration-dependent manner. Rats were administered once daily by gavage with perilla oil for 1 week, carotid arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Perilla oil delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 0.5 mL/kg. In addition, a high dose (2 mL/kg) of perilla oil greatly prevented the occlusion, comparable to the effect of aspirin (30 mg/kg). The results indicate that perilla oil inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is proposed that perilla oil could be a good candidate without adverse effects for the improvement of blood flow. PMID:24707301

  1. Multicentre standardisation of a clinical grade procedure for the preparation of allogeneic platelet concentrates from umbilical cord blood

    PubMed Central

    Rebulla, Paolo; Pupella, Simonetta; Santodirocco, Michele; Greppi, Noemi; Villanova, Ida; Buzzi, Marina; De Fazio, Nicola; Grazzini, Giuliano

    2016-01-01

    Background In addition to a largely prevalent use for bleeding prophylaxis, platelet concentrates from adult blood have also been used for many years to prepare platelet gels for the repair of topical skin ulcers. Platelet gel can be obtained by activation of fresh, cryopreserved, autologous or allogeneic platelet concentrates with calcium gluconate, thrombin and/or batroxobin. The high content of tissue regenerative factors in cord blood platelets and the widespread availability of allogeneic cord blood units generously donated for haematopoietic transplant but unsuitable for this use solely because of low haematopoietic stem cell content prompted us to develop a national programme to standardise the production of allogeneic cryopreserved cord blood platelet concentrates (CBPC) suitable for later preparation of clinical-grade cord blood platelet gel. Materials and methods Cord blood units collected at public banks with total nucleated cell counts <1.5×109, platelet count >150×109/L and volume >50 mL, underwent soft centrifugation within 48 hours of collection. Platelet-rich plasma was centrifuged at high speed to obtain a CBPC with target platelet concentration of 800–1,200×109/L, which was cryopreserved, without cryoprotectant, below −40 °C. Results During 14 months, 13 banks produced 1,080 CBPC with mean (± standard deviation) volume of 11.4±4.4 mL and platelet concentration of 1,003±229×109/L. Total platelet count per CBPC was 11.3±4.9×109. Platelet recovery from cord blood was 47.7±17.8%. About one-third of cord blood units donated for haematopoietic transplant could meet the requirements for preparation of CBPC. The cost of preparation was € 160.92/CBPC. About 2 hours were needed for one technician to prepare four CBPC. Discussion This study yielded valuable scientific and operational information regarding the development of clinical trials using allogeneic CBPC. PMID:26509822

  2. Genomic landscape of megakaryopoiesis and platelet function defects

    PubMed Central

    Bianchi, Elisa; Norfo, Ruggiero; Pennucci, Valentina; Zini, Roberta

    2016-01-01

    Megakaryopoiesis is a complex, stepwise process that takes place largely in the bone marrow. At the apex of the hierarchy, hematopoietic stem cells undergo a number of lineage commitment decisions that ultimately lead to the production of polyploid megakaryocytes. On average, megakaryocytes release 1011 platelets per day into the blood that repair vascular injuries and prevent excessive bleeding. This differentiation process is tightly controlled by exogenous and endogenous factors, which have been the topics of intense research in the hematopoietic field. Indeed, a skewing of megakaryocyte commitment and differentiation may entail the onset of myeloproliferative neoplasms and other preleukemic disorders together with acute megakaryoblastic leukemia, whereas quantitative or qualitative defects in platelet production can lead to inherited platelet disorders. The recent advent of next-generation sequencing has prompted mapping of the genomic landscape of these conditions to provide an accurate view of the underlying lesions. The aims of this review are to introduce the physiological pathways of megakaryopoiesis and to present landmark studies on acquired and inherited disorders that target them. These studies have not only introduced a new era in the fields of molecular medicine and targeted therapies but may also provide us with a better understanding of the mechanisms underlying normal megakaryopoiesis and thrombopoiesis that can inform efforts to create alternative sources of megakaryocytes and platelets. PMID:26787733

  3. The influence of Rubus idaeus and Rubus caesius leaf extracts on platelet aggregation in whole blood. Cross-talk of platelets and neutrophils.

    PubMed

    Dudzinska, Dominika; Bednarska, Katarzyna; Boncler, Magdalena; Luzak, Boguslawa; Watala, Cezary

    2016-07-01

    Recently, polyphenols have gained attention as potential natural cardioprotective therapeutics, due to their antiplatelet, anti-inflammatory and anticoagulant activity. Species belonging to the genus Rubus sp. have been reported to be a source of polyphenolic compounds with antioxidative proprieties and beneficial biological activities. This study investigates the effects of leaf extracts obtained from red raspberry (Rubus idaeus L.) and European dewberry (Rubus caesius L.) on the reactivity of blood platelets. In ADP-stimulated blood, raspberry and dewberry extracts (15 µg/ml) markedly decreased platelet surface membrane expression of activated GPIIbIIIa receptor by 16% and 21%, respectively (P < 0.01) and significantly inhibited platelet aggregation (by 31-41% for raspberry and by 38-55% for dewberry, P < 0.01). In platelet-rich plasma (PRP), the extracts had no effect on ADP-induced platelet aggregation. The effectiveness of the extracts in whole blood and the lack of their activity in PRP indicate that leukocytes are likely to participate in the platelet response to the extracts. Our experiments show that the extracts significantly reduced the amount of free radicals released by activated neutrophils in whole blood (P < 0.001), as well as in suspensions of isolated neutrophils (P < 0.05). Moreover, the reduced number of neutrophils leads to the decreased efficiency of the extracts in the inhibition of platelet aggregation. In summary, our findings show that the raspberry and dewberry leaf extracts considerably modulated blood platelet reactivity in whole blood: they influenced blood platelet aggregation, possibly via the modulation of the redox status dependent on the oxidative activity of neutrophils. PMID:26836594

  4. p38 mitogen-activated protein kinase activation during platelet storage: consequences for platelet recovery and hemostatic function in vivo

    PubMed Central

    Canault, Matthias; Duerschmied, Daniel; Brill, Alexander; Stefanini, Lucia; Schatzberg, Daphne; Cifuni, Stephen M.

    2010-01-01

    Platelets undergo several modifications during storage that reduce their posttransfusion survival and functionality. One important feature of these changes, which are known as platelet storage lesion, is the shedding of the surface glycoproteins GPIb-α and GPV. We recently demonstrated that tumor necrosis factor-α converting enzyme (TACE/ADAM17) mediates mitochondrial injury-induced shedding of adhesion receptors and that TACE activity correlates with reduced posttransfusion survival of these cells. We now confirm that TACE mediates receptor shedding and clearance of platelets stored for 16 hours at 37°C or 22°C. We further demonstrate that both storage and mitochondrial injury lead to the phosphorylation of p38 mitogen-activated kinase (MAPK) in platelets and that TACE-mediated receptor shedding from mouse and human platelets requires p38 MAP kinase signaling. Protein kinase C, extracellular regulated-signal kinase MAPK, and caspases were not involved in TACE activation. Both inhibition of p38 MAPK and inactivation of TACE during platelet storage led to a markedly improved posttransfusion recovery and hemostatic function of platelets in mice. p38 MAPK inhibitors had only minor effects on the aggregation of fresh platelets under static or flow conditions in vitro. In summary, our data suggest that inhibition of p38 MAPK or TACE during storage may significantly improve the quality of stored platelets. PMID:19965619

  5. The in vitro effect of aspirin on increased whole blood platelet aggregation in oral contraceptive users.

    PubMed

    Norris, L A; Bonnar, J

    1994-05-01

    The effects of triphasic oral contraceptives on whole blood platelet aggregation in 36 Italian women are reported here. Aspirin's effects on platelet aggregation were also studied. 18 women took a triphasic oral contraceptive; 10 women took Trinordiol, while 8 took Trinovum for at least 90 days. The remaining 18 women took nothing and served as controls. The study was aligned with each woman's birth control pill cycle. Blood was taken daily on days 15-21 of their cycle. Either saline solution or acetylsalicylic acid was added to the blood samples and compared. All data was statistically analyzed using unpaired student's t-test. Effects of 3 aggregating agents, ADP, PAF, and EDTA, on platelet aggregation were studied. Arachidonic acid and adrenalin bitartrate were also studied in this manner. An increase in platelet aggregation was observed in women taking oral contraceptives. No difference was found between patients taking Trinordiol and those taking Trinovum. The results of this study indicate an increase in whole blood platelet sensitivity to collagen, adrenalin, and arachidonic acid when using oral contraceptives. Aspirin, at low doses, may have a role in preventing early thrombus formation in women taking oral contraceptives. PMID:8042198

  6. Cathepsin G-Dependent Modulation of Platelet Thrombus Formation In Vivo by Blood Neutrophils

    PubMed Central

    Faraday, Nauder; Schunke, Kathryn; Saleem, Sofiyan; Fu, Juan; Wang, Bing; Zhang, Jian; Morrell, Craig; Dore, Sylvain

    2013-01-01

    Neutrophils are consistently associated with arterial thrombotic morbidity in human clinical studies but the causal basis for this association is unclear. We tested the hypothesis that neutrophils modulate platelet activation and thrombus formation in vivo in a cathepsin G-dependent manner. Neutrophils enhanced aggregation of human platelets in vitro in dose-dependent fashion and this effect was diminished by pharmacologic inhibition of cathepsin G activity and knockdown of cathepsin G expression. Tail bleeding time in the mouse was prolonged by a cathepsin G inhibitor and in cathepsin G knockout mice, and formation of neutrophil-platelet conjugates in blood that was shed from transected tails was reduced in the absence of cathepsin G. Bleeding time was highly correlated with blood neutrophil count in wildtype but not cathepsin G deficient mice. In the presence of elevated blood neutrophil counts, the anti-thrombotic effect of cathepsin G inhibition was greater than that of aspirin and additive to it when administered in combination. Both pharmacologic inhibition of cathepsin G and its congenital absence prolonged the time for platelet thrombus to form in ferric chloride-injured mouse mesenteric arterioles. In a vaso-occlusive model of ischemic stroke, inhibition of cathepsin G and its congenital absence improved cerebral blood flow, reduced histologic brain injury, and improved neurobehavioral outcome. These experiments demonstrate that neutrophil cathepsin G is a physiologic modulator of platelet thrombus formation in vivo and has potential as a target for novel anti-thrombotic therapies. PMID:23940756

  7. Platelet and red blood cell interactions and their role in rheumatoid arthritis.

    PubMed

    Olumuyiwa-Akeredolu, Oore-Ofe O; Pretorius, Etheresia

    2015-12-01

    Cytokines, lymphocytes, platelets and several biomolecules have long been implicated in the pathology of rheumatoid arthritis (RA), and the influences of antibody production and tagging, and cytokine, chemokine and enzyme production at specific rheumatoid joints were thought to be exclusive to the advancement of disease parameters. Another role player in RA is red blood cells (RBCs) which, of late, have been found to be involved in RA pathobiology, as there is a positive correlation between RBC counts and joint pathology, as well as with inflammatory biomarkers in the disease. There is also an association between RBC distribution width and the incidence of myocardial infarction amongst RA patients, and there is a change in the lipid distribution within RBC membranes. Of late, certain RBC-associated factors with previously obscure roles and cell-derived particles thought to be inconsequential to the other constituents of plasma were found to be active biomolecular players. Several of these have been discovered to be present in or originating from RBCs. Their influences have been shown to involve in membrane dynamics that cause structural and functional changes in both platelets and RBCs. RBC-derived microparticles are emerging entities found to play direct roles in immunomodulation via interactions with other plasma cells. These correlations highlight the direct influences of RBCs on exacerbating RA pathology. This review will attempt to shed more light on how RBCs, in the true inflammatory milieu of RA, are playing an even greater role than previously assumed. PMID:26059943

  8. A Real-Time Monitoring System to Assess the Platelet Aggregatory Capacity of Components of a Tissue-Engineered Blood Vessel Wall.

    PubMed

    Musa, Faiza Idris; Harper, Alan G S; Yang, Ying

    2016-07-01

    Native blood vessels contain both an antiaggregatory intimal layer, which prevents platelet activation in the intact vessel, and a proaggregatory medial layer, which stimulates platelet aggregation upon vascular damage. Yet, current techniques for assessing the functional properties of tissue-engineered blood vessels may not be able to assess the relative effectiveness of both these pro- and antiaggregatory properties of the vessel construct. In this study, we present a novel technique for quantitatively assessing the pro- and antiaggregatory properties of different three-dimensional blood vessel constructs made using a layered fabrication method. This technique utilizes real-time measurements of cytosolic Ca(2+) signaling to assess platelet activation in fluorescently labeled human platelet suspensions using fluorescence spectrofluorimetry, while also permitting examination of thrombus formation upon the surface of the construct using fluorescent imaging of DiOC6-labeled platelets. Experiments using this method demonstrated that type I collagen hydrogels, commonly used as scaffolds for vascular tissue engineering, were unable to support significant platelet activation, while type I and III neo-collagen secreted from human coronary artery smooth muscle cells cultured within these hydrogels as the medial layer were able to support thrombus formation. The incorporation of an intimal layer consisting of human umbilical vein endothelial cells on top of the medial layer inhibited platelet activation and aggregation. These data demonstrate that the methodology presented here is able to quantitatively compare the capacity of different constructs to trigger or prevent platelet activation. As such, this technique may provide a useful tool for standardizing the assessment of the functional properties of tissue-engineered blood vessel constructs developed using different culturing techniques. PMID:27260694

  9. A Real-Time Monitoring System to Assess the Platelet Aggregatory Capacity of Components of a Tissue-Engineered Blood Vessel Wall

    PubMed Central

    Musa, Faiza Idris

    2016-01-01

    Native blood vessels contain both an antiaggregatory intimal layer, which prevents platelet activation in the intact vessel, and a proaggregatory medial layer, which stimulates platelet aggregation upon vascular damage. Yet, current techniques for assessing the functional properties of tissue-engineered blood vessels may not be able to assess the relative effectiveness of both these pro- and antiaggregatory properties of the vessel construct. In this study, we present a novel technique for quantitatively assessing the pro- and antiaggregatory properties of different three-dimensional blood vessel constructs made using a layered fabrication method. This technique utilizes real-time measurements of cytosolic Ca2+ signaling to assess platelet activation in fluorescently labeled human platelet suspensions using fluorescence spectrofluorimetry, while also permitting examination of thrombus formation upon the surface of the construct using fluorescent imaging of DiOC6-labeled platelets. Experiments using this method demonstrated that type I collagen hydrogels, commonly used as scaffolds for vascular tissue engineering, were unable to support significant platelet activation, while type I and III neo-collagen secreted from human coronary artery smooth muscle cells cultured within these hydrogels as the medial layer were able to support thrombus formation. The incorporation of an intimal layer consisting of human umbilical vein endothelial cells on top of the medial layer inhibited platelet activation and aggregation. These data demonstrate that the methodology presented here is able to quantitatively compare the capacity of different constructs to trigger or prevent platelet activation. As such, this technique may provide a useful tool for standardizing the assessment of the functional properties of tissue-engineered blood vessel constructs developed using different culturing techniques. PMID:27260694

  10. Coated platelets function in platelet-dependent fibrin formation via integrin αIIbβ3 and transglutaminase factor XIII

    PubMed Central

    Mattheij, Nadine J.A.; Swieringa, Frauke; Mastenbroek, Tom G.; Berny-Lang, Michelle A.; May, Frauke; Baaten, Constance C.F.M.J.; van der Meijden, Paola E.J.; Henskens, Yvonne M.C.; Beckers, Erik A.M.; Suylen, Dennis P.L.; Nolte, Marc W.; Hackeng, Tilman M.; McCarty, Owen J.T.; Heemskerk, Johan W.M.; Cosemans, Judith M.E.M.

    2016-01-01

    Coated platelets, formed by collagen and thrombin activation, have been characterized in different ways: i) by the formation of a protein coat of α-granular proteins; ii) by exposure of procoagulant phosphatidylserine; or iii) by high fibrinogen binding. Yet, their functional role has remained unclear. Here we used a novel transglutaminase probe, Rhod-A14, to identify a subpopulation of platelets with a cross-linked protein coat, and compared this with other platelet subpopulations using a panel of functional assays. Platelet stimulation with convulxin/thrombin resulted in initial integrin αIIbβ3 activation, the appearance of a platelet population with high fibrinogen binding, (independently of active integrins, but dependent on the presence of thrombin) followed by phosphatidylserine exposure and binding of coagulation factors Va and Xa. A subpopulation of phosphatidylserine-exposing platelets bound Rhod-A14 both in suspension and in thrombi generated on a collagen surface. In suspension, high fibrinogen and Rhod-A14 binding were antagonized by combined inhibition of transglutaminase activity and integrin αIIbβ3. Markedly, in thrombi from mice deficient in transglutaminase factor XIII, platelet-driven fibrin formation and Rhod-A14 binding were abolished by blockage of integrin αIIbβ3. Vice versa, star-like fibrin formation from platelets of a patient with deficiency in αIIbβ3 (Glanzmann thrombasthenia) was abolished upon blockage of transglutaminase activity. We conclude that coated platelets, with initial αIIbβ3 activation and high fibrinogen binding, form a subpopulation of phosphatidylserine-exposing platelets, and function in platelet-dependent star-like fibrin fiber formation via transglutaminase factor XIII and integrin αIIbβ3. PMID:26721892

  11. Nattokinase improves blood flow by inhibiting platelet aggregation and thrombus formation.

    PubMed

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang Sei; Park, Sung Kyeong; Lee, Sung-Pyo; Choi, Ehn-Kyoung; Rhee, Man Hee; Kim, Yun-Bae

    2013-12-01

    The effects of nattokinase on the in vitro platelet aggregation and in vivo thrombosis were investigated in comparison with aspirin. Rabbit platelet-rich plasma was incubated with nattokinase and aggregation inducers collagen and thrombin, and the platelet aggregation rate was analyzed. Nattokinase significantly inhibited both the collagen- and thrombin-induced platelet aggregations. Nattokinase also reduced thromboxane B2 formation from collagen-activated platelets in a concentration-dependent manner. Rats were orally administered with nattokinase for 1 week, and their carotid arteries were exposed. Arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Nattokinase delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 160 mg/kg. In addition, a high dose (500 mg/kg) of nattokinase fully prevented the occlusion, as achieved with aspirin (30 mg/kg). The results indicate that nattokinase extracted from fermented soybean inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is suggested that nattokinase could be a good candidate without adverse effects for the improvement of blood flow. PMID:24396387

  12. Nattokinase improves blood flow by inhibiting platelet aggregation and thrombus formation

    PubMed Central

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang Sei; Park, Sung Kyeong; Lee, Sung-Pyo; Choi, Ehn-Kyoung

    2013-01-01

    The effects of nattokinase on the in vitro platelet aggregation and in vivo thrombosis were investigated in comparison with aspirin. Rabbit platelet-rich plasma was incubated with nattokinase and aggregation inducers collagen and thrombin, and the platelet aggregation rate was analyzed. Nattokinase significantly inhibited both the collagen- and thrombin-induced platelet aggregations. Nattokinase also reduced thromboxane B2 formation from collagen-activated platelets in a concentration-dependent manner. Rats were orally administered with nattokinase for 1 week, and their carotid arteries were exposed. Arterial thrombosis was induced by applying 35% FeCl3-soaked filter paper for 10 min, and the blood flow was monitored with a laser Doppler probe. Nattokinase delayed the FeCl3-induced arterial occlusion in a dose-dependent manner, doubling the occlusion time at 160 mg/kg. In addition, a high dose (500 mg/kg) of nattokinase fully prevented the occlusion, as achieved with aspirin (30 mg/kg). The results indicate that nattokinase extracted from fermented soybean inhibit platelet aggregation by blocking thromboxane formation, and thereby delay thrombosis following oxidative arterial wall injury. Therefore, it is suggested that nattokinase could be a good candidate without adverse effects for the improvement of blood flow. PMID:24396387

  13. Antiplatelet drugs in patients with enhanced platelet turnover: biomarkers versus platelet function testing.

    PubMed

    Freynhofer, Matthias K; Gruber, Susanne C; Grove, Erik L; Weiss, Thomas W; Wojta, Johann; Huber, Kurt

    2015-08-31

    Platelets are key players in atherothrombosis. Antiplatelet therapy comprising aspirin alone or with P2Y12-inhibitors are effective for prevention of atherothrombotic complications. However, there is interindividual variability in the response to antiplatelet drugs, leaving some patients at increased risk of recurrent atherothrombotic events. Several risk factors associated with high on-treatment platelet reactivity (HTPR), including elevated platelet turnover, have been identified. Platelet turnover is adequately estimated from the fraction of reticulated platelets. Reticulated platelets are young platelets, characterised by residual messenger RNA. They are larger, haemostatically more active and there is evidence that platelet turnover is a causal and prognostic factor in atherothrombotic disease. Whether platelet turnover per se represents a key factor in pathogenesis, progression and prognosis of atherothrombotic diseases (with focus on acute coronary syndromes) or whether it merely facilitates insufficient platelet inhibition will be discussed in this state-of-the art review. PMID:26272640

  14. The Actin and Myosin Filaments of Human and Bovine Blood Platelets

    PubMed Central

    Zucker-Franklin, Dorothea; Grusky, George

    1972-01-01

    The contractility of platelets has been attributed to an actomyosin-like protein which has been well defined on a physicochemical basis. Moreover, platelets contain ±80 A filaments which resemble actin filaments in smooth muscle. Studies were undertaken on human and bovine platelets to better define the morphologic structures which may subserve this contractile function. In order to identify actin, the ability of the filaments to react with heavy meromyosin (HMM) was tested. Accordingly, platelets were glycerinated and treated with HMM. In addition, platelet actin was extracted, reacted with HMM, and examined by negative staining. In both instances typical arrowhead structures with clearly defined polarity and a periodicity of ±360 A formed. As is the case with purified muscle actin, the complexes were dissociable with Mg-ATP. The formation of myosin-like filaments was observed when osmotically shocked platelets were incubated with MgCl2 and excess ATP. These “thick” filaments measured 250-300 A in width, tapered at both ends and often occurred in clumps. They resembled aggregates of thick filaments described in contracted smooth muscle. Extraction of platelets by methods suitable for the demonstration of myosin showed filaments with an average length of 0.3 μ, a smooth shaft, and frayed or bulbous ends. These appeared identical to those seen in synthetically prepared myosin of striated muscle. It is suggested that the filaments described here represent the actin and myosin of platelets. Images PMID:4333023

  15. Visualization of nitric oxide production by individual platelets during adhesion in flowing blood.

    PubMed

    Cozzi, Maria Rita; Guglielmini, Giuseppe; Battiston, Monica; Momi, Stefania; Lombardi, Elisabetta; Miller, Edward Cole; De Zanet, Denise; Mazzucato, Mario; Gresele, Paolo; De Marco, Luigi

    2015-01-22

    Nitric oxide (NO) exerts vasodilatatory, antiplatelet, antioxidant, and antiproliferative effects. Endothelium-derived NO has been shown to be of crucial importance in cardiovascular protection, whereas evidence that NO is synthesized by platelets and regulates platelet function is still controversial. By using a sensitive and specific fluorescent probe, 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM), we visualized NO production in individual platelets undergoing adhesion on a collagen substrate under flow conditions. NO production, monitored in real time, was dependent on the shear rates applied, increasing with the raising of the shear rates. Furthermore, NO production increased in the presence of l-arginine (nitric-oxide synthase [NOS] substrate), and it decreased in the presence of L-NG-monomethyl arginine (L-NMMA) (NOS inhibitor) but not of D-NG-monomethyl arginine (D-NMMA) (L-NMMA-inactive enantiomer). Platelet deposition, measured with mepacrine-labeled platelets, was inversely related to NO production. A correlation was evident between Ca(++) elevation and NO production, suggesting that platelet NO formation is triggered by intracytoplasmic Ca(++) elevation. Simultaneous measurement of NO and Ca(++) indicated that NO production in individual platelets is preceded by Ca(++) elevations, with a lag phase of 33 ± 9.5 s. Our studies provide the first direct demonstration of platelet NO production triggered by the interaction with an activating surface under flow and suggest that intraplatelet Ca(++) elevation elicits the production of NO which, in turn, modulates thrombus size. PMID:25480660

  16. Effect of Blood Shear Forces on Platelet Mediated Thrombosis Inside Arterial Stenosis.

    NASA Astrophysics Data System (ADS)

    Maalej, Nabil

    Shear induced activation of platelets plays a major role in the onset of thrombosis in atherosclerotic arteries. Blood hemodynamics and its effect on platelet kinetics has been studied mainly in in vitro and in ex vivo experiments. We designed new in vivo methods to study blood hemodynamic effects on platelet kinetics in canine stenosed carotid arteries. A carotid artery-jugular vein anastomotic shunt was produced. Intimal damage and controlled variations in the degree of stenosis were produced on the artery. An inflatable cuff was placed around the jugular vein to control vascular resistance. An electromagnetic flowmeter was used to measure blood flow. Doppler ultrasound crystals were used to measure the velocity profiles inside and distal to the stenosis. Stenosis geometry was obtained using digital subtraction angiography and quantitative arteriography. Using these measurements we calculated the wall shear stress using the finite difference solution of the Navier-Stokes equations. To study platelet kinetics, autologous platelets were labeled with Indium Oxine and injected IV. A collimated Nal gamma counter was placed over the stenosis to detect radio-labeled platelet accumulation as platelet mediated thrombi formed in the stenosis. The radioactive count rate increased in an inverse parallel fashion to the decline in flow rate during thrombus formation. The platelet accumulation increased with the increase of percent stenosis and was maximal at the narrow portion of the stenosis. Acute thrombus formation leading to arterial occlusion was only observed for stenosis higher than 70 +/- 5%. Platelet accumulation rate was not significant until the pressure gradient across the stenosis exceeded 40 +/- 10 mmHg. Totally occlusive thrombus formation was only observed for shear stresses greater than a critical value of 100 +/- 10 Pa. Beyond this critical value acute platelet thrombus formation increased exponentially with shear. Increased shear stresses were found to

  17. Hemostatic function of apheresis platelets stored at 4 °C and 22 °C

    PubMed Central

    Reddoch, Kristin M.; Pidcoke, Heather F.; Montgomery, Robbie K.; Fedyk, Criselda G.; Aden, James K.; Ramasubramanian, Anand K.; Cap, Andrew P.

    2014-01-01

    Introduction Platelet refrigeration decreases the risk of bacterial contamination and may preserve function better than standard-of-care room temperature storage. Benefits could include lower transfusion-related complications, decreased costs, improved hemostasis in acutely bleeding patients, and extended shelf-life. In this study, we compared the effects of 22°C and 4°C storage on the functional and activation status of apheresis platelets (APs). Methods APs (n = 5 per group) were stored for 5 days at 22°C with agitation (RT) versus at 4°C with agitation (4C+AG) and without (4C). Measurements included platelet counts, mean platelet volume, blood gas analytes, aggregation response, thromboelastography, TxB2 and sCD40L release, activation markers and microparticle formation. Results Sample pH levels were within acceptable limits for storage products (pH 6.2-7.4). Platelet glucose metabolism (P < 0.05), aggregation response (ADP: RT 0; 4C+AG 5.0 ± 0.8; 4C 5.6 ± 0.9; P < 0.05), and clot strength (MA: RT 58 ± 2; 4C+AG 63 ± 2; 4C 67 ± 2; P < 0.05) were better preserved at 4°C compared to RT storage. Refrigerated samples were more activated compared to RT (P < 0.05), although TxB2 (P < 0.05) and sCD40L release (P < 0.05) were higher at RT. Agitation did not improve the quality of 4°C-stored samples. Conclusion AP stored at 4°C maintain more viable metabolic characteristics, are hemostatically more effective, and release fewer pro-inflammatory mediators than AP stored at RT over 5 days. Given the superior bacteriologic safety of refrigerated products, these data suggest that cold-stored platelets may improve outcomes for acutely bleeding patients. PMID:24169210

  18. The effect of oral phenylbutazone on whole blood platelet aggregation in the dog.

    PubMed Central

    Jackson, M L; Searcy, G P; Olexson, D W

    1985-01-01

    Platelet aggregation to collagen, arachidonic acid and adenosine diphosphate was evaluated in six dogs using a whole blood electronic aggregometer. The six dogs were then given phenylbutazone orally according to four different dosage levels and durations of treatment. Aggregation responses were measured at established intervals of time following phenylbutazone administration. Data on untreated dogs indicated that arachidonic acid, at a final concentration of 50 micrograms/mL and collagen, at a final concentration of 5 micrograms/mL, were useful agents for studying whole blood platelet aggregation in the dog, but adenosine diphosphate, at a final concentration of 30 microM was not. The high single dose (900 mg) of phenylbutazone significantly inhibited platelet aggregation to arachidonic acid at 1.5,4,7 and 12 hours following administration. The results indicated that the whole blood electronic aggregometer was of limited value in detecting subtle changes in platelet aggregation. It was concluded, however, that the instrument is potentially useful as a rapid screening aid for detecting canine patients at high risk of platelet-related bleeding problems. PMID:3930056

  19. Common variants in the human platelet PAR4 thrombin receptor alter platelet function and differ by race

    PubMed Central

    Edelstein, Leonard C.; Simon, Lukas M.; Lindsay, Cory R.; Kong, Xianguo; Teruel-Montoya, Raúl; Tourdot, Benjamin E.; Chen, Edward S.; Ma, Lin; Coughlin, Shaun; Nieman, Marvin; Holinstat, Michael; Shaw, Chad A.

    2014-01-01

    Human platelets express 2 thrombin receptors: protease-activated receptor (PAR)-1 and PAR4. Recently, we reported 3.7-fold increased PAR4-mediated aggregation kinetics in platelets from black subjects compared with white subjects. We now show that platelets from blacks (n = 70) express 14% more PAR4 protein than those from whites (n = 84), but this difference is not associated with platelet PAR4 function. Quantitative trait locus analysis identified 3 common single nucleotide polymorphisms in the PAR4 gene (F2RL3) associated with PAR4-induced platelet aggregation. Among these single nucleotide polymorphisms, rs773902 determines whether residue 120 in transmembrane domain 2 is an alanine (Ala) or threonine (Thr). Compared with the Ala120 variant, Thr120 was more common in black subjects than in white subjects (63% vs 19%), was associated with higher PAR4-induced human platelet aggregation and Ca2+ flux, and generated greater inositol 1,4,5-triphosphate in transfected cells. A second, less frequent F2RL3 variant, Phe296Val, was only observed in blacks and abolished the enhanced PAR4-induced platelet aggregation and 1,4,5-triphosphate generation associated with PAR4-Thr120. PAR4 genotype did not affect vorapaxar inhibition of platelet PAR1 function, but a strong pharmacogenetic effect was observed with the PAR4-specific antagonist YD-3 [1-benzyl-3(ethoxycarbonylphenyl)-indazole]. These findings may have an important pharmacogenetic effect on the development of new PAR antagonists. PMID:25293779

  20. The miRNA Profile of Platelets Stored in a Blood Bank and Its Relation to Cellular Damage from Storage

    PubMed Central

    Maués, Jersey Heitor da Silva; Lamarão, Letícia Martins; de Lemos, José Alexandre Rodrigues; Montenegro, Raquel Carvalho; Burbano, Rommel Mário Rodriguez

    2015-01-01

    Millions of blood products are transfused each year, and many lives are directly affected by transfusion. Platelet concentrate (PC) is one of the main products derived from blood. Even under good storage conditions, PC is likely to suffer cell damage. The shape of platelets changes after 5 to 7 days of storage at 22°C. Taking into consideration that some platelet proteins undergo changes in their shape and functionality during PC storage. Sixteen PC bags were collected and each PC bag tube was cut into six equal pieces to perform experiments with platelets from six different days of storage. Thus, on the first day of storage, 1/6 of the tube was used for miRNA extraction, and the remaining 5/6 was stored under the same conditions until extraction of miRNAs on each the following five days. Samples were sequenced on an Illumina Platform to demonstrate the most highly expressed miRNAs. Three miRNAs, mir127, mir191 and mir320a were validated by real-time quantitative PCR (RQ-PCR) in 100 PC bags tubes. Our method suggests, the use of the miRNAs mir127 and mir320a as biomarkers to assess the "validity period" of PC bags stored in blood banks for long periods. Thus, bags can be tested on the 5th day of storage for the relative expression levels of mir127 and mir320a. Thus, we highlight candidate miRNAs as biomarkers of storage damage that can be used as tools to evaluate the quality of stored PC. The use of miRNAs as biomarkers of damage is unprecedented and will contribute to improved quality of blood products for transfusions. PMID:26121269

  1. The miRNA Profile of Platelets Stored in a Blood Bank and Its Relation to Cellular Damage from Storage.

    PubMed

    Pontes, Thaís Brilhante; Moreira-Nunes, Caroline de Fátima Aquino; Maués, Jersey Heitor da Silva; Lamarão, Letícia Martins; de Lemos, José Alexandre Rodrigues; Montenegro, Raquel Carvalho; Burbano, Rommel Mário Rodriguez

    2015-01-01

    Millions of blood products are transfused each year, and many lives are directly affected by transfusion. Platelet concentrate (PC) is one of the main products derived from blood. Even under good storage conditions, PC is likely to suffer cell damage. The shape of platelets changes after 5 to 7 days of storage at 22°C. Taking into consideration that some platelet proteins undergo changes in their shape and functionality during PC storage. Sixteen PC bags were collected and each PC bag tube was cut into six equal pieces to perform experiments with platelets from six different days of storage. Thus, on the first day of storage, 1/6 of the tube was used for miRNA extraction, and the remaining 5/6 was stored under the same conditions until extraction of miRNAs on each the following five days. Samples were sequenced on an Illumina Platform to demonstrate the most highly expressed miRNAs. Three miRNAs, mir127, mir191 and mir320a were validated by real-time quantitative PCR (RQ-PCR) in 100 PC bags tubes. Our method suggests, the use of the miRNAs mir127 and mir320a as biomarkers to assess the "validity period" of PC bags stored in blood banks for long periods. Thus, bags can be tested on the 5th day of storage for the relative expression levels of mir127 and mir320a. Thus, we highlight candidate miRNAs as biomarkers of storage damage that can be used as tools to evaluate the quality of stored PC. The use of miRNAs as biomarkers of damage is unprecedented and will contribute to improved quality of blood products for transfusions. PMID:26121269

  2. Blood flow reductions in stenosed canine coronary arteries: vasospasm or platelet aggregation?

    PubMed

    Folts, J D; Gallagher, K; Rowe, G G

    1982-02-01

    In 67 dogs with a 60-80% coronary stenosis produced by an external constricting plastic ring, blood flow measured with an electromagnetic flowmeter showed cyclical flow reductions of varying magnitude and duration, and then an abrupt return to control flow. In 45 dogs, heparin did not prevent these flow reductions, but ibuprofen (Motrin) or indomethacin abolished them. With incremental doses of each of these drugs, the cyclical flow reduction and the platelet function in vitro were diminished proportionately. In 10 more dogs, during low flow, pinching or poking the narrowed vessel suddenly restored normal flow. Topical application of papaverine and nitroglycerin proximal to the stenosis did not abolish the cyclic flow reduction, although a transient fall in systemic pressure indicated that they had been absorbed. Seven dogs had the constricting cylinder and flow probe chronically implanted for 4-6 weeks. A single oral dose of aspirin, 20 mg/kg, abolished their cyclic flow reductions for 2-4 days. In five dogs with 70% stenosis in the circumflex coronary artery, coronary arteriography was performed before coronary flow reduction and when coronary blood flow was low. This showed that there was a considerable additional reduction in the size of the mechanically constricted lumen during spontaneous flow reduction. In one dog, a nonopacified mass was dislodged from the area of constriction in 67 msec and this restored the lumen to its control diameter. Similar rapid clearing was filmed in two more dogs. In no case was vasospasm observed. These results suggest that obstruction from platelets aggregated in the narrowed lumen caused the cyclic flow reductions. PMID:7053882

  3. Effect of an electrical left ventricular assist device on red blood cell and platelet survival in the cow. Technical report

    SciTech Connect

    Melaragno, A.J.; Vecchione, J.J.; Katchis, R.J.; Abdu, W.A.; Ouellet, R.P.

    1982-04-23

    Blood volume measurements were made in cows after infusion of human 125 iodine albumin and autologous 51 chromium-labeled red blood cells. Repeated intravenous infusions of iodinated human albumin did not appear to isosensitize the cows. When the cow red blood cells were incubated at 37 C after labeling with 51 chromium, there was elution of the 51 chromium, and the 51 chromium T 50 values were 45 hours in both healthy cows and cows with LVAD's. Measurements also were made in the cow platelets labeled with 51 chromium or 111 Indium-oxine. The platelets labeled with 51 chromium had T 50 values of 4 days, and platelets labeled with 111 Indium-oxine had T 50 values of 0.9 to 2.7 days. 51 chromium-labeled platelets had similar T 50 values in healthy cows and cows with LVAD's. Bovine platelets isolated from units of blood using serial differential centrifugation were labeled with 51 chromium or with 111 Indium-oxine, and after infusion in healthy cows and cows with LVAD's measurements were made of platelet circulation and distribution. The disappearance of platelet radioactivity from the blood was linear with time, and the platelet lifespan was 6-10 days. The presence of an LVAD did not affect initial recovery or lifespan of cow platelets.

  4. Effects of antihypertensive treatment on platelet function in essential hypertension.

    PubMed

    Gomi, T; Ikeda, T; Shibuya, Y; Nagao, R

    2000-11-01

    To evaluate the effect of antihypertensive therapy on platelet activation in essential hypertension, the plasma levels of beta-thromboglobulin (beta-TG) were examined in 45 patients with essential hypertension and 20 age-matched normotensive control subjects. Hypertensive patients were assigned to monotherapy with one of five different antihypertensive drugs for 6 months, and the change of plasma levels of beta-TG was reexamined after the completion of the monotherapy. The plasma beta-TG increased in hypertensive patients compared with levels in normotensive control subjects. Monotherapy with each drug resulted in sufficient blood pressure control in all hypertensive patients. The plasma beta-TG decreased significantly after monotherapy with an alpha-blocker or an angiotensin-converting enzyme inhibitor (ACEI). The plasma beta-TG increased with the use of a diuretic but did not change with the use of a beta-blocker or calcium antagonist. The platelet activation observed in patients with essential hypertension is reversed by monotherapy with an alpha-blocker or an ACEI. It is possible that these drugs reduce the development of hypertensive vascular complications due to suppression of platelet activation in patients with essential hypertension. PMID:11131267

  5. Platelet kinetics with indium-111 platelets: comparison with chromium-51 platelets.

    PubMed

    Peters, A M; Lavender, J P

    1983-04-01

    The application of 111In-oxine to platelet labeling has contributed to the understanding of platelet kinetics along three lines: 1. It allows the measurement of new parameters of splenic function, such as the intrasplenic platelet transit time, which has shed new light on the physiology of splenic blood cell handling. 2. It facilitates the measurement of platelet life span in conditions, such as ITP, in which 51Cr may undergo undesirable elution from the platelet as a result of platelet-antibody interaction. 3. It allows the determination of the fate of platelets, that is, the site of platelet destruction in conditions in which reduced platelet life span is associated with abnormal platelet consumption, as a result of either premature destruction of "abnormal" platelets by the RE system, or the consumption (or destruction) of normal platelets after their interaction with an abnormal vasculature. Future research using 111In platelets may yield further valuable information on the control as well as the significance of intrasplenic platelet pooling, on the role of platelets in the development of chronic vascular lesions, and on the sites of platelet destruction in ITP. With regard to the latter, methods will have to be developed for harvesting sufficient platelets representative of the total circulating platelet population from severely thrombocytopenic patients for autologous platelet labeling. This would avoid the use of homologous platelets, which is likely to be responsible for some of the contradictory data relating to the use of radiolabeled platelet studies for the prediction of the response of patients with ITP to splenectomy. PMID:6346489

  6. Model of platelet transport in flowing blood with drift and diffusion terms.

    PubMed Central

    Eckstein, E C; Belgacem, F

    1991-01-01

    A drift term is added to the convective diffusion equation for platelet transport so that situations with near-wall excesses of platelets can be described. The mathematical relationship between the drift and the fully developed, steady-state platelet concentration profile is shown and a functional form of the drift that leads to concentration profiles similar to experimentally determined profiles is provided. The transport equation is numerically integrated to determine concentration profiles in the developing region of a tube flow. With the approximate drift function and typical values of augmented diffusion constant, the calculated concentration profiles have near-wall excesses that mimic experimental results, thus implying the extended equation is a valid description of rheological events. Stochastic differential equations that are equivalent to the convective diffusion transport equation are shown, and simulations with them are used to illustrate the impact of the drift term on platelet concentration profiles during deposition in a tube flow. PMID:1883945

  7. Long-term untreated streptozotocin-diabetes leads to increased expression and elevated activity of prostaglandin H2 synthase in blood platelets.

    PubMed

    Siewiera, Karolina; Kassassir, Hassan; Talar, Marcin; Wieteska, Lukasz; Watala, Cezary

    2016-05-01

    In diabetes-related states of chronic hyperglycaemia elevated concentrations of glucose may alter the functioning of platelet enzymes involved in arachidonic acid metabolism, including prostaglandin H2 synthase (cyclooxygenase) (PGHS, COX). Therefore, the principal aim of this study was to assess the effects of experimental chronic hyperglycaemia on platelet PGHS-1 (COX-1) expression and activity. Blood platelet activation and reactivity were assessed in Sprague-Dawley rats with the 5-month streptozotocin (STZ) diabetes. The PGHS-1 abundance in platelets was evaluated with flow cytometry and Western blotting, while its activity monitored using a high resolution respirometry and the peroxidase fluorescent assay. The production of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) in platelets were assayed immunoenzymatically. Circulating platelets from diabetic were characterised by increased size, elevated 'priming' and altered reactivity, compared to non-diabetic animals. Both Western blot analysis and flow cytometry revealed significantly elevated expressions of platelet PGHS-1 in STZ-diabetic rats (p < 0.05). We also observed significantly elevated platelet PGHS-1-related arachidonic acid metabolism in diabetic vs. non-diabetic animals, with the use of polarographic (p < 0.05) and total activity assay (p < 0.001). Such increases were accompanied by the elevated production of PGE2 (p < 0.001) and TXB2 (p < 0.05) in diabetic animals. The increased PGHS-1-dependent oxygen consumption and the total activity of PGHS-1 in diabetic animals remained very significant (p < 0.001) also upon adjusting for blood platelet PGHS-1 abundance. Therefore, our results further contribute to the explanation of the increased metabolism of arachidonic acid observed in diabetes. PMID:26325148

  8. Aspirin insensitive thrombophilia: Transcript profiling of blood identifies platelet abnormalities and HLA restriction

    PubMed Central

    Fallahi, Payam; Katz, Richard; Toma, Ian; Li, Ranyang; Reiner, Jonathan; VanHouten, Kiersten; Carpio, Larry; Marshall, Lorraine; Lian, Yi; Bupp, Sujata; Fu, Sidney W.; Rickles, Frederick; Leitenberg, David; Lai, Yinglei; Weksler, Babette B.; Rebling, Frederik; Yang, Zhaoqing; McCaffrey, Timothy A.

    2016-01-01

    Aspirin is the most widely used antiplatelet agent because it is safe, efficient, and inexpensive. However, a significant subset of patients does not exhibit a full inhibition of platelet aggregation, termed ‘aspirin resistance’ (AR). Several major studies have observed that AR patients have a 4-fold increased risk of myocardial infarction (MI), stroke, and other thrombotic events. Arachidonic acid-stimulated whole blood aggregation was tested in 132 adults at risk for ischemic events, and identified an inadequate response to aspirin therapy in 9 patients (6.8%). Expression profiling of blood RNA by microarray was used to generate new hypotheses about the etiology of AR. Among the differentially expressed genes, there were decreases in several known platelet transcripts, including clusterin (CLU), glycoproteins IIb/IIIa (ITGA2B/3), lipocalin (LCN2), lactoferrin (LTF), and the thrombopoetin receptor (MPL), but with increased mRNA for the T-cell Th1 chemokine CXCL10. There was a strong association of AR with expression of HLA-DRB4 and HLA-DQA1. Similar HLA changes have been linked to autoimmune disorders, particularly antiphospholipid syndrome (APS), in which autoantibodies to phospholipid/protein complexes can trigger platelet activation. Consistent with APS, AR patients exhibited a 30% reduction in platelet counts. Follow-up testing for autoimmune antibodies observed only borderline titers in AR patients. Overall, these results suggest that AR may be related to changes in platelet gene expression creating a hyperreactive platelet, despite antiplatelet therapy. Future studies will focus on determining the protein levels of these differential transcripts in platelets, and the possible involvement of HLA restriction as a contributing factor. PMID:23454623

  9. White blood cell and platelet indices as prognostic markers in patients with invasive ductal breast carcinoma

    PubMed Central

    Mantas, Dimitrios; Kostakis, Ioannis D.; Machairas, Nikolaos; Markopoulos, Christos

    2016-01-01

    A growing body of evidence suggests that oncogenesis is associated with systemic inflammation. The present study investigated white blood cell and platelet indices, whose values change during the inflammatory response, in women with invasive ductal breast carcinoma. Preoperatively obtained white blood cell and platelet counts from 53 patients with early breast cancer, who developed systemic metastases over a mean follow-up period of 65 months, were analyzed and compared with those of a matching control group formed of 37 patients with the same characteristics, who remained recurrence-free during the same time period. Patients who developed distant metastasis had a significantly higher mean platelet volume and lower neutrophil count than patients who did not present with distant metastasis. Furthermore, time to distant metastasis development was longer in patients with a lower mean platelet volume, whilst patients with a lower neutrophil count had a shorter systemic disease-free time interval. However, receiver operating characteristic curve analysis demonstrated that these parameters provided moderate accuracy in predicting which patients may develop distant metastasis. No differences were detected between patient groups regarding additional parameters. Patients who developed systemic disease during a mean follow-up period of 65 months were observed to have an increased mean platelet volume and decreased neutrophil count preoperatively. These results indicate that such parameters may be of prognostic value in patients with breast cancer. Studies with a larger number of patients are required to further investigate this hypothesis. PMID:27446480

  10. Keishibukuryogan, a Traditional Japanese Medicine, Inhibits Platelet Aggregation in Guinea Pig Whole Blood

    PubMed Central

    Terawaki, Kiyoshi; Noguchi, Masamichi; Yuzurihara, Mitsutoshi; Omiya, Yuji; Ikarashi, Yasushi; Kase, Yoshio

    2015-01-01

    Effects of keishibukuryogan (KBG) on platelet aggregation were investigated. To ensure the specificity of KBG, tokishakuyakusan (TSS) and kamisyoyosan (KSS), which are known to have platelet aggregation-inhibiting effects, and rikkunshito (RKT) and shakuyakukanzoto (SKT), which are considered to be devoid of such effects, were used for comparison. The platelet aggregation of each test drug was measured by the screen filtration pressure method using whole blood of guinea pigs and expressed as a collagen-induced pressure rate (%) or a collagen concentration required for 50% increase in the pressure rate (PATI value). KBG suppressed the collagen-induced whole blood pressure rate increase and increased the PATI value, like TSS and KSS. Neither RKT nor SKT showed these effects. The Moutan cortex and Cinnamomi cortex, the constituent crude drugs of KBG, showed KBG-like pressure rate suppression and PATI-increasing effects. Furthermore, paeonol, a representative component of Moutan cortex, and aspirin which is known to have platelet aggregation-inhibiting activity (COX-1 inhibitor) also showed similar effects. These results suggest that the platelet aggregation-inhibiting activity of the constituent crude drugs Moutan cortex and Cinnamomi cortex is involved in the improving effects of KBG on impaired microcirculation and that paeonol plays a role in these effects. PMID:26379740

  11. Potential use of blood bank platelet concentrates to accelerate wound healing of diabetic ulcers.

    PubMed

    Han, Seung-Kyu; Kim, Deok-Woo; Jeong, Seong-Ho; Hong, Yong-Taek; Woo, Hong-Suh; Kim, Woo-Kyung; Gottrup, Finn

    2007-11-01

    Many clinical trials have shown the effectiveness of platelet releasates on diabetic wound healing, but large volumes of blood must be aspirated from patients and a platelet separator is required. This study was undertaken to investigate the potential of blood bank platelet concentrate (BBPC) for accelerating diabetic wound healing. Platelet-derived growth factor-BB (PDGF-BB) contents in BBPC were determined by enzyme-linked immunosorbent assay in vitro, and the in vivo study involved comparing extents of wound healing in BBPC-treated and control groups using diabetic mouse wound models. In the in vitro study, 5.2 +/- 1.2 pg of PDGF-BB was found to be released by 1 million platelets in fresh BBPC, and adding thrombin to BBPC significantly increased the levels of PDGF-BB released. Our in vivo study in diabetic mice revealed that BBPC treatment greatly accelerated wound healing. Our results suggest that BBPC has potential to accelerate the healing of diabetic ulcers. PMID:17992147

  12. Effects of polyphenol-rich extract from berries of Aronia melanocarpa on the markers of oxidative stress and blood platelet activation.

    PubMed

    Olas, Beata; Kedzierska, Magdalena; Wachowicz, Barbara; Stochmal, Anna; Oleszek, Wieslaw

    2010-01-01

    Bioactive substances found in numerous foods can be successfully and safely used to modify various cellular functions and affect the oxidative stress. Aronia melanocarpa fruits (Rosaceae) are one of the richest plant sources of phenolic substances shown to have anti-inflammatory, antitumor, antioxidative and antiplatelet activities. We investigated antioxidant properties of the extract from berries of A. melanocarpa by the estimation of the selected and other biomarkers of oxidative stress, i.e. the level of 8-epi-prostaglandin F(2) (8-EPI) (by immunoassay kit) and the amount of glutathione (by HPLC method) in control platelets and platelets treated with H(2)O(2). The expression of alpha(IIb)beta(3) (a marker of platelet activation) was measured by flow cytometer. The antioxidative and antiplatelet properties of the tested extract were also compared with the action of a well characterized antioxidative and antiplatelet commercial monomeric polyphenol-resveratrol. The extract from berries of A. melanocarpa (at the highest tested concentration -100 microg/ml) decreased the production of 8-EPI (a marker of lipid peroxidation) in control blood platelets and platelets treated with H(2)O(2) (2 mM). A combined action of the tested plant extract and H(2)O(2) evoked a significant increase of reduced form of glutathione in platelets compared with cells treated with H(2)O(2) only. Moreover, the tested plant extract (at the highest used concentration -100 microg/ml) reduced the expression of alpha(IIb)beta(3) on blood platelets. Comparative studies indicate that the tested plant extract was found to be more reactive in blood platelets than the solution of pure resveratrol. PMID:20218910

  13. Blood

    MedlinePlus

    ... solid part of your blood contains red blood cells, white blood cells, and platelets. Red blood cells (RBC) deliver oxygen from your lungs to your tissues and organs. White blood cells (WBC) fight infection and are part of your ...

  14. Effects of the extract from Conyza canadensis on human blood platelet aggregation.

    PubMed

    Saluk-Juszczak, J; Olas, B; Pawlaczyk, I; Gancarz, R; Wachowicz, B

    2007-06-01

    The effects of different parts of extract from medicinal plant Conyza canadensis, used to control bleeding, on human blood platelet aggregation in vitro were investigated. Aqueous extract of Conyza c. from young or old plants, glycoconjugate part, polysaccharide part and aglycon part at the concentrations above 0.75 mg/ml strongly inhibited platelet aggregation induced by collagen (2 microg/ml) in dose-dependent manner. Polysaccharide part isolated from plant extract had the strongest inhibitory effect on aggregation stimulated by collagen and seems to be responsible for antiaggregatory properties. PMID:17660590

  15. Altered Platelet Function in Intrauterine Growth Restriction: A Cause or a Consequence of Uteroplacental Disease?

    PubMed

    Müllers, Sieglinde M; Burke, Naomi; Flood, Karen; Cowman, Jonathan; O'connor, Hugh; Cotter, Brian; Kearney, Morgan; Dempsey, Mark; Dicker, Patrick; Tully, Elizabeth; Geary, Michael P; Kenny, Dermot; Malone, Fergal D

    2016-07-01

    Objective A limited number of platelet function studies in intrauterine growth restriction (IUGR) have yielded conflicting results. We sought to evaluate platelet reactivity in IUGR using a novel platelet aggregation assay. Study Design Pregnancies with IUGR were recruited from 24 weeks' gestation (estimated fetal weight < 10th centile) and had platelet function testing performed after diagnosis. A modification of light transmission aggregometry created dose-response curves of platelet reactivity in response to multiple agonists at differing concentrations. Findings were compared with healthy third trimester controls. IUGR cases with a subsequent normal birth weight were analyzed separately. Results In this study, 33 pregnancies retained their IUGR diagnosis at birth, demonstrating significantly reduced platelet reactivity in response to all agonists (arachidonic acid, adenosine diphosphate, collagen, thrombin receptor-activating peptide, and epinephrine) when compared with 36 healthy pregnancy controls (p < 0.0001). Similar results were obtained for cases demonstrating an increasing in utero growth trajectory. When IUGR preceded preeclampsia or gestational hypertension, platelet function was significantly reduced compared with normotensive IUGR. Conclusion Using this comprehensive platelet assay, we have demonstrated a functional impairment of platelets in IUGR. This may reflect platelet-derived placental growth factor release. Further evaluation of platelet function may aid in the development of future platelet-targeted therapies for uteroplacental disease. PMID:26906182

  16. The saliva proteome of the blood-feeding insect Triatoma infestans is rich in platelet-aggregation inhibitors

    NASA Astrophysics Data System (ADS)

    Charneau, Sébastien; Junqueira, Magno; Costa, Camila M.; Pires, Daniele L.; Fernandes, Ellen S.; Bussacos, Ana C.; Sousa, Marcelo V.; Ricart, Carlos André O.; Shevchenko, Andrej; Teixeira, Antonio R. L.

    2007-12-01

    The saliva of the bloodsucking bug Triatoma infestans vector of Chagas disease contains an anti-hemostatic molecular cocktail that prevents coagulation, vasoconstriction and platelet aggregation in a vertebrate prey. In order to characterize T. infestans saliva proteome, we separated the secreted saliva by two-dimensional gel electrophoresis (2-DE). More than 200 salivary proteins were detected on the 2-DE map, mainly in the alkaline region. By nanoLC-MS/MS analysis using a LTQ-Orbitrap equipment followed by a combination of conventional and sequence-similarity searches, we identified 58 main protein spots. Most of such proteins possess potential blood-feeding associated functions, particularly anti-platelet aggregation proteins belonging to lipocalin and apyrase families. The saliva protein composition indicates a highly specific molecular mechanism of early response to platelet aggregation. This first proteome analysis of the T. infestans secreted saliva provides a basis for a better understanding of this fluid protein composition highly directed to counterpart hemostasis of the prey, thus promoting the bug's blood-feeding.

  17. Increased platelet oxidative metabolism, blood oxidative stress and neopterin levels after ultra-endurance exercise.

    PubMed

    de Lucas, Ricardo Dantas; Caputo, Fabrizio; Mendes de Souza, Kristopher; Sigwalt, André Roberto; Ghisoni, Karina; Lock Silveira, Paulo Cesar; Remor, Aline Pertile; da Luz Scheffer, Débora; Guglielmo, Luiz Guilherme Antonacci; Latini, Alexandra

    2014-01-01

    The purpose of the present investigation was to identify muscle damage, inflammatory response and oxidative stress blood markers in athletes undertaking the ultra-endurance MultiSport Brazil race. Eleven well-trained male athletes (34.3 ± 3.1 years, 74.0 ± 7.6 kg; 172.2 ± 5.1 cm) participated in the study and performed the race, which consisted of about 90 km of alternating off-road running, mountain biking and kayaking. Twelve hours before and up to 15 minutes after the race a 10 mL blood sample was drawn in order to measure the following parameters: lactate dehydrogenase and creatine kinase activities, lipid peroxidation, catalase activity, protein carbonylation, respiratory chain complexes I, II and IV activities, oxygen consumption and neopterin concentrations. After the race, plasma lactate dehydrogenase and creatine kinase activities were significantly increased. Erythrocyte TBA-RS levels and plasma protein carbonylation were markedly augmented in post-race samples. Additionally, mitochondrial complex II activity and oxygen consumption in post-race platelet-rich plasma were also increased. These altered biochemical parameters were accompanied by increased plasma neopterin levels. The ultra-endurance event provoked systemic inflammation (increased neopterin) accompanied by marked oxidative stress, likely by increasing oxidative metabolism (increased oxidative mitochondrial function). This might be advantageous during prolonged exercise, mainly for efficient substrate oxidation at the mitochondrial level, even when tissue damage is induced. PMID:24117160

  18. Expression of myotubularins in blood platelets: Characterization and potential diagnostic of X-linked myotubular myopathy.

    PubMed

    Mansour, Rana; Severin, Sonia; Xuereb, Jean-Marie; Gratacap, Marie-Pierre; Laporte, Jocelyn; Buj-Bello, Ana; Tronchère, Hélène; Payrastre, Bernard

    2016-07-29

    Phosphoinositides play a key role in the spatiotemporal control of central intracellular processes and several specific kinases and phosphatases regulating the level of these lipids are implicated in human diseases. Myotubularins are a family of 3-phosphatases acting specifically on phosphatidylinositol 3-monophosphate and phosphatidylinositol 3,5 bisphosphate. Members of this family are mutated in genetic diseases including myotubularin 1 (MTM1) and myotubularin-related protein 2 (MTMR2) which mutations are responsible of X-linked centronuclear myopathy and Charcot-Marie-Tooth neuropathy, respectively. Here we show that MTM1 is expressed in blood platelets and that hundred microliters of blood is sufficient to detect the protein by western blotting. Since the most severe cases of pathogenic mutations of MTM1 lead to loss of expression of the protein, we propose that a minimal amount of blood can allow a rapid diagnostic test of X-linked myotubular myopathy, which is currently based on histopathology of muscle biopsy and molecular genetic testing. In platelets, MTM1 is a highly active 3-phosphatase mainly associated to membranes and found on the dense granules and to a lesser extent on alpha-granules. However, deletion of MTM1 in mouse had no significant effect on platelet count and on platelet secretion and aggregation induced by thrombin or collagen stimulation. Potential compensation by other members of the myotubularin family is conceivable since MTMR2 was easily detectable by western blotting and the mRNA of several members of the family increased during in vitro differentiation of human megakaryocytes and MEG-01 cells. In conclusion, we show the presence of several myotubularins in platelets and propose that minimal amounts of blood can be used to develop a rapid diagnostic test for genetic pathologies linked to loss of expression of these phosphatases. PMID:27155155

  19. Life span and tissue distribution of 111indium-labeled blood platelets in hypomagnesemic lambs

    SciTech Connect

    Schneider, M.D.; Miller, J.K.; White, P.K.; Ramsey, N.

    1983-05-01

    Circulating platelets may be activated by exposed triple-helical collagen in atherosclerotic lesions in Mg-deficient ruminants. Autologous platelets, labeled in vitro with 111In and determined to be active, were injected into 5 hypomagnesemic and 3 control lambs fed semipurified diets with 100 or 2,000 mg of Mg/kg of feed for 3 months. During the first 68 hours, 111In concentrations were 11 times higher in packed cells than in plasma. Packed-cell 111In increased 60% during the first 2 hours, probably due to initial tissue sequestration and later release of labeled platelets. Thereafter, platelet half-life span averaged 60 and 63 hours for hypomagnesemic and control lambs. After 68 hours, lambs were injected with native vascular collagen fibrils at 500 micrograms/kg of body weight to initiate reversible platelet aggregation. Within 1 minute, 83% of packed-cell 111In disappeared from circulation. Thirty minutes later, the lambs were euthanatized and necropsied and in the lungs, liver, and spleen, 111In averaged 24%, 19%, and 9%, respectively, of 111In injected 68 hours earlier. Organ deposits were not affected by Mg intake, but 111In in the lungs was somewhat lower in 2 lambs injected with inactivated collagen. Pathologic changes induced by reversible platelet aggregation were compatible with right ventricular failure complicated by pulmonary edema, similar to changes in hypomagnesemic lambs that died spontaneously. Platelets in blood exposed to vascular lesions in hypomagnesemic ruminants could be a major mortality risk factor in grass tetany disease.

  20. Numerical Investigation of the Effects of Channel Geometry on Platelet Activation and Blood Damage

    PubMed Central

    Wu, Jingshu; Yun, B. Min; Fallon, Anna M.; Hanson, Stephen R.; Aidun, Cyrus K.; Yoganathan, Ajit P.

    2011-01-01

    Thromboembolic complications in Bileaflet mechanical heart valves (BMHVs) are believed to be due to the combination of high shear stresses and large recirculation regions. Relating blood damage to design geometry is therefore essential to ultimately optimize the design of BMHVs. The aim of this research is to quantitatively study the effect of 3D channel geometry on shear-induced platelet activation and aggregation, and to choose an appropriate blood damage index (BDI) model for future numerical simulations. The simulations in this study use a recently developed lattice-Boltzmann with external boundary force (LBM-EBF) method [Wu, J., and C. K. Aidun. Int. J. Numer. Method Fluids 62(7):765–783, 2010; Wu, J., and C. K. Aidun. Int. J. Multiphase flow 36:202–209, 2010]. The channel geometries and flow conditions are re-constructed from recent experiments by Fallon [The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets in School of Chemical and Biomolecular Engineering. Atlanta: Georgia Institute of Technology] and Fallon et al. [Ann. Biomed. Eng. 36(1):1]. The fluid flow is computed on a fixed regular ‘lattice’ using the LBM, and each platelet is mapped onto a Lagrangian frame moving continuously throughout the fluid domain. The two-way fluid–solid interactions are determined by the EBF method by enforcing a no-slip condition on the platelet surface. The motion and orientation of the platelet are obtained from Newtonian dynamics equations. The numerical results show that sharp corners or sudden shape transitions will increase blood damage. Fallon’s experimental results were used as a basis for choosing the appropriate BDI model for use in future computational simulations of flow through BMHVs. PMID:20976558

  1. The role of point-of-care assessment of platelet function in predicting postoperative bleeding and transfusion requirements after coronary artery bypass grafting

    PubMed Central

    Mishra, Pankaj Kumar; Thekkudan, Joyce; Sahajanandan, Raj; Gravenor, Mike; Lakshmanan, Suresh; Fayaz, Khazi Mohammed; Luckraz, Heyman

    2015-01-01

    Objective: Objective platelet function assessment after cardiac surgery can predict postoperative blood loss, guide transfusion requirements and discriminate the need for surgical re-exploration. We conducted this study to assess the predictive value of point-of-care testing platelet function using the Multiplate® device. Methods: Patients undergoing isolated coronary artery bypass grafting were prospectively recruited (n = 84). Group A (n = 42) patients were on anti-platelet therapy until surgery; patients in Group B (n = 42) stopped anti-platelet treatment at least 5 days preoperatively. Multiplate® and thromboelastography (TEG) tests were performed in the perioperative period. Primary end-point was excessive bleeding (>2.5 ml/kg/h) within first 3 h postoperative. Secondary end-points included transfusion requirements, re-exploration rates, intensive care unit and in-hospital stays. Results: Patients in Group A had excessive bleeding (59% vs. 33%, P = 0.02), higher re-exploration rates (14% vs. 0%, P < 0.01) and higher rate of blood (41% vs. 14%, P < 0.01) and platelet (14% vs. 2%, P = 0.05) transfusions. On multivariate analysis, preoperative platelet function testing was the most significant predictor of excessive bleeding (odds ratio [OR]: 2.3, P = 0.08), need for blood (OR: 5.5, P < 0.01) and platelet transfusion (OR: 15.1, P < 0.01). Postoperative “ASPI test” best predicted the need for transfusion (sensitivity - 0.86) and excessive blood loss (sensitivity - 0.81). TEG results did not correlate well with any of these outcome measures. Conclusions: Peri-operative platelet functional assessment with Multiplate® was the strongest predictor for bleeding and transfusion requirements in patients on anti-platelet therapy until the time of surgery. Study registration: ISRCTN43298975 (http://www.controlled-trials.com/ISRCTN43298975/). PMID:25566711

  2. Alterations of platelet functions in children and adolescents with iron-deficiency anemia and response to therapy.

    PubMed

    Mokhtar, Galila M; Ibrahim, Wafaa E; Kassim, Nevine A; Ragab, Iman A; Saad, Abeer A; Abdel Raheem, Heba G

    2015-01-01

    Several changes in platelets have been reported in patients with iron-deficiency anemia (IDA), so a relationship between iron metabolism and thrombopoiesis should be considered. We aimed to study the alterations of platelet functions in patients with IDA by assessment of platelet aggregation with epinephrine, adenosine diphosphate (ADP) and ristocetin and by measuring platelet function analyzer-100 (PFA-100) closure time together with the effect of iron therapy on the same tests. A follow-up study was conducted in Ain Shams University Children's hospital in the period from June 2011 to June 2012 including 20 patients with confirmed IDA and 20 healthy age- and sex-matched control. Bleeding manifestations were reported. Laboratory analysis included complete blood count, assessment of iron status by measuring serum iron, TIBC and ferritin, assessment of platelet functions by PFA-100 closure time and platelet aggregation with collagen, ADP and ristocetin. Patients with IDA were treated by oral iron therapy 6 mg/kg/day of ferrous sulfate and post-therapeutic re-assessment was done. Mean age of IDA patients was 5.7 ± 4.2 years. Bleeding manifestations were more common in patients group. Mean PFA-100 closure times (with epinephrine) were significantly longer in patients (179.1 ± 86.4 seconds) compared to control group (115 ± 28.5 seconds) (p < 0.05). Platelet aggregation by ADP (38.1 ± 22.2%), epinephrine (19.7 ± 14.2%) and ristocetin (58.8 ± 21.4%) were significantly reduced in patients compared to control (62.7 ± 6.2, 63.3 ± 6.9, 73.8 ± 8.3, respectively; p < 0.001). After treatment platelet aggregation tests induced by ADP (64.78 ± 18.25%), and epinephrine (55.47 ± 24%) were significantly increased in patients with IDA compared to before treatment (39.44 ± 21.85%, 20.33 ± 14.58%; p < 0.001). PFA-100 closure time as well showed significant decreased after treatment (118.4 ± 27.242) compared to before treatment (186.2 ± 90.35; p < 0.05). A negative

  3. Usefulness of platelet function tests to predict bleeding with antithrombotic medications.

    PubMed

    Gorog, Diana A; Otsui, Kazunori; Inoue, Nobutaka

    2015-01-01

    The pharmacological inhibition of platelets has always been regarded as a double-edged sword: the challenge of balancing the antithrombotic effect against the bleeding risk. Potent antiplatelet agents and novel oral anticoagulants, sometimes in combination, are increasingly used in the treatment of cardiovascular disease and for thromboprophylaxis in atrial fibrillation. Although such treatment has reduced the risk of thrombotic events, the potential for major bleeding has increased, and a technique to identify those at increased bleeding risk is greatly needed. Platelet function tests (PFTs), most frequently VerifyNow and also the vasodilator-stimulated phosphoprotein -phosphorylation assay, have been used to identify low on-treatment platelet reactivity, to identify individuals who may be at increased bleeding risk. Such results predict nuisance bleeding, but many individuals have low on-treatment platelet reactivity and yet do not exhibit major or even minor bleeding. Although PFTs may be useful in assessing populations, they do not allow identification of individual patients at risk of bleeding on either antiplatelet or novel oral anticoagulant therapy, nor do they allow the tailoring of such therapy to optimize the risk:benefit ratio. Thrombin plays a cardinal role in both arterial thrombus formation and hemostasis, yet most PFTs fail to assess the contribution of thrombin, because they employ anticoagulated blood. Techniques such as the calibrated automated thrombogram and the point-of-care global thrombosis test, performed on native blood, which measure endogenous thrombin potential, seem to show the most promise for profiling bleeding risk, as tests that most physiologically assess the effects of medications on thrombin. PMID:25839991

  4. Increased levels of platelet-activating factor in blood following intestinal ischemia in the dog.

    PubMed

    Filep, J; Hermán, F; Braquet, P; Mózes, T

    1989-01-31

    The possible role of platelet-activating factor (PAF) in superior mesenteric artery occlusion induced circulatory collapse was studied in anesthetized dogs. PAF was measured by platelet aggregation assay. Identity of PAF-like product in blood was ascertained by thin layer chromatography, high pressure liquid chromatography and alkaline treatment. Low amount of PAF was detected in the mesenteric blood under normal conditions, during reperfusion PAF levels were significantly higher. Pretreatment of the animals with BN 52021, a specific PAF receptor antagonist abolished the fall in mean arterial pressure and the rise in hematocrit due to ischemia/reperfusion. These findings suggest that PAF may play an important role in mesenteric ischemia-induced circulatory collapse. PMID:2916986

  5. Platelet-derived CXCL12 regulates monocyte function, survival, differentiation into macrophages and foam cells through differential involvement of CXCR4–CXCR7

    PubMed Central

    Chatterjee, M; von Ungern-Sternberg, S N I; Seizer, P; Schlegel, F; Büttcher, M; Sindhu, N A; Müller, S; Mack, A; Gawaz, M

    2015-01-01

    Platelets store and release CXCL12 (SDF-1), which governs differentiation of hematopoietic progenitors into either endothelial or macrophage-foam cells. CXCL12 ligates CXCR4 and CXCR7 and regulates monocyte/macrophage functions. This study deciphers the relative contribution of CXCR4–CXCR7 in mediating the effects of platelet-derived CXCL12 on monocyte function, survival, and differentiation. CXCL12 and macrophage migration inhibitory factor (MIF) that ligate CXCR4–CXCR7 induced a dynamic bidirectional trafficking of the receptors, causing CXCR4 internalization and CXCR7 externalization during chemotaxis, thereby influencing relative receptor availability, unlike MCP-1. In vivo we found enhanced accumulation of platelets and platelet-macrophage co-aggregates in peritoneal fluid following induction of peritonitis in mice. The relative surface expression of CXCL12, CXCR4, and CXCR7 among infiltrated monocytes was also enhanced as compared with peripheral blood. Platelet-derived CXCL12 from collagen-adherent platelets and recombinant CXCL12 induced monocyte chemotaxis specifically through CXCR4 engagement. Adhesion of monocytes to immobilized CXCL12 and CXCL12-enriched activated platelet surface under static and dynamic arterial flow conditions were mediated primarily through CXCR7 and were counter-regulated by neutralizing platelet-derived CXCL12. Monocytes and culture-derived-M1–M2 macrophages phagocytosed platelets, with the phagocytic potential of culture-derived-M1 macrophages higher than M2 involving CXCR4–CXCR7 participation. CXCR7 was the primary receptor in promoting monocyte survival as exerted by platelet-derived CXCL12 against BH3-mimetic induced apoptosis (phosphatidylserine exposure, caspase-3 activation, loss of mitochondrial transmembrane potential). In co-culture experiments with platelets, monocytes predominantly differentiated into CD163+ macrophages, which was attenuated upon CXCL12 neutralization and CXCR4/CXCR7 blocking antibodies

  6. Flow cytometric comparison of platelets from a whole blood and finger-prick sample: impact of 24 hours storage.

    PubMed

    Swanepoel, Albe C; Stander, Andre; Pretorius, Etheresia

    2013-03-01

    In this study, we investigate the validity and laboratory utility of flow cytometry when analyzing platelet activation by studying CD41, CD42b, CD62P and CD63. We compare flow cytometry results from citrated whole-blood and finger-prick samples directly after collection and also after storing both a finger-prick and whole-blood sample for 24 hours. Citrated whole-blood and finger-prick samples were taken from three healthy individuals on two occasions, and a total of 60,000 cells were analyzed for each of the four phycoerythrin-labeled monoclonal antibodies. Half of each sample was analyzed immediately after sampling while the other half was kept in the fridge at 6 °C for 24 hours before analysis. No significant difference was found between the sampling methods or the period of time before analysis. Results therefore suggest that an appropriately prepared finger-prick sample can be used for platelet function analysis, and samples can be stored for 24 hours in the fridge at 6 °C before analysis. PMID:23320994

  7. Variation of red blood cell distribution width and mean platelet volume after moderate endurance exercise.

    PubMed

    Lippi, Giuseppe; Salvagno, Gian Luca; Danese, Elisa; Tarperi, Cantor; Guidi, Gian Cesare; Schena, Federico

    2014-01-01

    Although physical exercise strongly influences several laboratory parameters, data about the hematological changes after medium distance running are scarce. We studied 31 middle-trained athletes (mean training regimen 217 ± 32 min/week) who performed a 21.1 km, half-marathon run. Blood samples were collected before the run, at the end, and 3 and 20 hours thereafter. The complete blood count was performed on Advia 2120 and included red blood cell (RBC), reticulocyte, and platelet counts; hemoglobin; mean corpuscular volume (MCV); mean corpuscular hemoglobin (MCH); reticulocyte haemoglobin content (Ret CHR); RBC distribution width (RDW), mean platelet volume (MPV). No significant variations were observed for MCH and Ret CHR. The RBC, reticulocyte, and hemoglobin values modestly decreased after the run. The MCV significantly increased at the end of running but returned to baseline 3 hours thereafter. The RDW constantly increased, reaching a peak 20 hours after the run. The platelet count and MPV both increased after the run and returned to baseline 3 hours thereafter. These results may have implications for definition of reference ranges and antidoping testing, and may also contribute to explaining the relationship between endurance exercise and mortality, since previous studies reported that RDW and MPV may be significantly associated with cardiovascular disease. PMID:25197280

  8. White blood cell count, sex and age are major determinants of heterogeneity of platelet indices in an adult general population: results from the MOLI-SANI project

    PubMed Central

    Santimone, Iolanda; Di Castelnuovo, Augusto; De Curtis, Amalia; Spinelli, Maria; Cugino, Daniela; Gianfagna, Francesco; Zito, Francesco; Donati, Maria Benedetta; Cerletti, Chiara; de Gaetano, Giovanni; Iacoviello, Licia

    2011-01-01

    Background The understanding of non-genetic regulation of platelet indices - platelet count, plateletcrit, mean platelet volume, and platelet distribution width - is limited. The association of these platelet indices with a number of biochemical, environmental and clinical variables was studied in a large cohort of the general population. Design and Methods Men and women (n=18,097, 52% women, 56±12 years) were randomly recruited from various villages in Molise (Italy) in the framework of the population-based cohort study “Moli-sani”. Hemochromocytometric analyses were performed using an automatic analyzer (Beckman Coulter, IL, Milan, Italy). Associations of platelet indices with dependent variables were investigated by multivariable linear regression analysis. Results Full models including age, sex, body mass index, blood pressure, smoking, menopause, white and red blood cell counts, mean corpuscular volume, D-dimers, C-reactive protein, high-density lipoproteins, low-density lipoproteins, triglycerides, glucose, and drug use explained 16%, 21%, 1.9% and 4.7% of platelet count, plateletcrit, mean platelet volume and platelet distribution width variability, respectively; variables that appeared to be most strongly associated were white blood cell count, age, and sex. Platelet count, mean platelet volume and plateletcrit were positively associated with white blood cell count, while platelet distribution width was negatively associated with white blood cell count. Platelet count and plateletcrit were also positively associated with C-reactive protein and D-dimers (P<0.0001). Each of the other variables, although associated with platelet indices in a statistically significant manner, only explained less than 0.5% of their variability. Platelet indices varied across Molise villages, independently of any other platelet count determinant or characteristics of the villages. Conclusions The association of platelet indices with white blood cell count, C-reactive protein

  9. Anti-thrombogenic properties of a nitric oxide-releasing dextran derivative: evaluation of platelet activation and whole blood clotting kinetics

    PubMed Central

    Damodaran, Vinod B.; Leszczak, Victoria; Wold, Kathryn A.; Lantvit, Sarah M.; Popat, Ketul C.; Reynolds, Melissa M.

    2013-01-01

    Controlling platelet activation and clotting initiated by cardiovascular interventions remains a major challenge in clinical practice. In this work, the anti-thrombotic properties of a polysaccharide-based nitric oxide (NO)-releasing dextran derivative are presented. Total platelet adhesion, platelet morphology and whole blood clotting kinetics were used as indicators to evaluate the anti-clotting properties of this material. With a total NO delivery of 0.203±0.003 μmol, the NO-releasing dextran derivative (Dex-SNO) mixed with blood plasma demonstrated a significantly lower amount of platelet adhesion and activation onto a surface and reduced whole blood clotting kinetics. Nearly 75% reduction in platelet adhesion and a significant retention of platelet morphology were observed with blood plasma treated with Dex-SNO, suggesting this to be a potential anti-platelet therapeutic agent for preventing thrombosis that does not have an adverse effect on circulating platelets. PMID:24349705

  10. Hippophae rhamnoides L. Fruits Reduce the Oxidative Stress in Human Blood Platelets and Plasma

    PubMed Central

    Olas, Beata; Kontek, Bogdan; Malinowska, Paulina; Żuchowski, Jerzy; Stochmal, Anna

    2016-01-01

    Effects of the phenolic fraction from Hippophae rhamnoides fruits on the production of thiobarbituric acid reactive substances (TBARS, a marker of lipid peroxidation) and the generation of superoxide anion (O2−∙) in human blood platelets (resting platelets and platelets stimulated by a strong physiological agonist, thrombin) were studied in vitro. We also examined antioxidant properties of this fraction against human plasma lipid peroxidation and protein carbonylation induced by a strong biological oxidant, hydrogen peroxide (H2O2) or H2O2/Fe (a donor of hydroxyl radicals). The tested fraction of H. rhamnoides (0.5– 50 µg/mL; the incubation time: 15 and 60 min) inhibited lipid peroxidation induced by H2O2 or H2O2/Fe. The H. rhamnoides phenolic fraction inhibited not only plasma lipid peroxidation, but also plasma protein carbonylation stimulated by H2O2 or H2O2/Fe. Moreover, the level of O2−∙ in platelets significantly decreased. In comparative experiments, the H. rhamnoides fraction was a more effective antioxidant than aronia extract or grape seed extract (at the highest tested concentration, 50 µg/mL). The obtained results suggest that H. rhamnoides fruits may be a new, promising source of natural compounds with antioxidant and antiplatelet activity beneficial not only for healthy people, but also for those with oxidative stress-associated diseases. PMID:26933473

  11. Hippophae rhamnoides L. Fruits Reduce the Oxidative Stress in Human Blood Platelets and Plasma.

    PubMed

    Olas, Beata; Kontek, Bogdan; Malinowska, Paulina; Żuchowski, Jerzy; Stochmal, Anna

    2016-01-01

    Effects of the phenolic fraction from Hippophae rhamnoides fruits on the production of thiobarbituric acid reactive substances (TBARS, a marker of lipid peroxidation) and the generation of superoxide anion (O2 (-∙)) in human blood platelets (resting platelets and platelets stimulated by a strong physiological agonist, thrombin) were studied in vitro. We also examined antioxidant properties of this fraction against human plasma lipid peroxidation and protein carbonylation induced by a strong biological oxidant, hydrogen peroxide (H2O2) or H2O2/Fe (a donor of hydroxyl radicals). The tested fraction of H. rhamnoides (0.5- 50 µg/mL; the incubation time: 15 and 60 min) inhibited lipid peroxidation induced by H2O2 or H2O2/Fe. The H. rhamnoides phenolic fraction inhibited not only plasma lipid peroxidation, but also plasma protein carbonylation stimulated by H2O2 or H2O2/Fe. Moreover, the level of O2 (-∙) in platelets significantly decreased. In comparative experiments, the H. rhamnoides fraction was a more effective antioxidant than aronia extract or grape seed extract (at the highest tested concentration, 50 µg/mL). The obtained results suggest that H. rhamnoides fruits may be a new, promising source of natural compounds with antioxidant and antiplatelet activity beneficial not only for healthy people, but also for those with oxidative stress-associated diseases. PMID:26933473

  12. Normalization methods in time series of platelet function assays

    PubMed Central

    Van Poucke, Sven; Zhang, Zhongheng; Roest, Mark; Vukicevic, Milan; Beran, Maud; Lauwereins, Bart; Zheng, Ming-Hua; Henskens, Yvonne; Lancé, Marcus; Marcus, Abraham

    2016-01-01

    Abstract Platelet function can be quantitatively assessed by specific assays such as light-transmission aggregometry, multiple-electrode aggregometry measuring the response to adenosine diphosphate (ADP), arachidonic acid, collagen, and thrombin-receptor activating peptide and viscoelastic tests such as rotational thromboelastometry (ROTEM). The task of extracting meaningful statistical and clinical information from high-dimensional data spaces in temporal multivariate clinical data represented in multivariate time series is complex. Building insightful visualizations for multivariate time series demands adequate usage of normalization techniques. In this article, various methods for data normalization (z-transformation, range transformation, proportion transformation, and interquartile range) are presented and visualized discussing the most suited approach for platelet function data series. Normalization was calculated per assay (test) for all time points and per time point for all tests. Interquartile range, range transformation, and z-transformation demonstrated the correlation as calculated by the Spearman correlation test, when normalized per assay (test) for all time points. When normalizing per time point for all tests, no correlation could be abstracted from the charts as was the case when using all data as 1 dataset for normalization. PMID:27428217

  13. Blood cells and endothelial barrier function.

    PubMed

    Rodrigues, Stephen F; Granger, D Neil

    2015-01-01

    The barrier properties of endothelial cells are critical for the maintenance of water and protein balance between the intravascular and extravascular compartments. An impairment of endothelial barrier function has been implicated in the genesis and/or progression of a variety of pathological conditions, including pulmonary edema, ischemic stroke, neurodegenerative disorders, angioedema, sepsis and cancer. The altered barrier function in these conditions is often linked to the release of soluble mediators from resident cells (e.g., mast cells, macrophages) and/or recruited blood cells. The interaction of the mediators with receptors expressed on the surface of endothelial cells diminishes barrier function either by altering the expression of adhesive proteins in the inter-endothelial junctions, by altering the organization of the cytoskeleton, or both. Reactive oxygen species (ROS), proteolytic enzymes (e.g., matrix metalloproteinase, elastase), oncostatin M, and VEGF are part of a long list of mediators that have been implicated in endothelial barrier failure. In this review, we address the role of blood borne cells, including, neutrophils, lymphocytes, monocytes, and platelets, in the regulation of endothelial barrier function in health and disease. Attention is also devoted to new targets for therapeutic intervention in disease states with morbidity and mortality related to endothelial barrier dysfunction. PMID:25838983

  14. Blood cells and endothelial barrier function

    PubMed Central

    Rodrigues, Stephen F; Granger, D Neil

    2015-01-01

    Abstract The barrier properties of endothelial cells are critical for the maintenance of water and protein balance between the intravascular and extravascular compartments. An impairment of endothelial barrier function has been implicated in the genesis and/or progression of a variety of pathological conditions, including pulmonary edema, ischemic stroke, neurodegenerative disorders, angioedema, sepsis and cancer. The altered barrier function in these conditions is often linked to the release of soluble mediators from resident cells (e.g., mast cells, macrophages) and/or recruited blood cells. The interaction of the mediators with receptors expressed on the surface of endothelial cells diminishes barrier function either by altering the expression of adhesive proteins in the inter-endothelial junctions, by altering the organization of the cytoskeleton, or both. Reactive oxygen species (ROS), proteolytic enzymes (e.g., matrix metalloproteinase, elastase), oncostatin M, and VEGF are part of a long list of mediators that have been implicated in endothelial barrier failure. In this review, we address the role of blood borne cells, including, neutrophils, lymphocytes, monocytes, and platelets, in the regulation of endothelial barrier function in health and disease. Attention is also devoted to new targets for therapeutic intervention in disease states with morbidity and mortality related to endothelial barrier dysfunction. PMID:25838983

  15. Differences in Whole Blood Platelet Aggregation at Baseline and in Response to Aspirin and Aspirin Plus Clopidogrel in Patients With Versus Without Chronic Kidney Disease.

    PubMed

    Jain, Nishank; Li, Xilong; Adams-Huet, Beverley; Sarode, Ravi; Toto, Robert D; Banerjee, Subhash; Hedayati, S Susan

    2016-02-15

    Thrombotic events while receiving antiplatelet agents (APAs) are more common in subjects with versus without chronic kidney disease (CKD). Data on antiplatelet effects of APA in CKD are scarce and limited by lack of baseline platelet function before APA treatment. We hypothesized subjects with stages 4 to 5 CKD versus no CKD have greater baseline platelet aggregability and respond poorly to aspirin and clopidogrel. In a prospective controlled study, we measured whole blood platelet aggregation (WBPA) in 28 CKD and 16 non-CKD asymptomatic stable outpatients not on APA, frequency-matched for age, gender, obesity, and diabetes mellitus. WBPA was remeasured after 2 weeks of each aspirin and aspirin plus clopidogrel. The primary outcome was percent inhibition of platelet aggregation (IPA) from baseline. The secondary outcome was residual platelet aggregability (RPA; proportion with <50% IPA). Baseline platelet aggregability was similar between groups except adenosine diphosphate-induced WBPA, which was higher in CKD versus non-CKD; median (interquartile range) = 13.5 (9.5 to 16.0) versus 9.0 (6.0 to 12.0) Ω, p = 0.007. CKD versus non-CKD participants had lower clopidogrel-induced IPA, 38% versus 72%, p = 0.04. A greater proportion of CKD versus non-CKD participants had RPA after clopidogrel treatment (56% vs 8.3%, p = 0.01). There were no significant interactions between CKD and the presence of cytochrome P450 2C19 polymorphisms for platelet aggregability in clopidogrel-treated participants. In conclusion, CKD versus non-CKD subjects exhibited similar platelet aggregation at baseline, similar aspirin effects and greater RPA on clopidogrel, which was independent of cytochrome P450 2C19 polymorphisms. PMID:26725101

  16. Drag-reducing polymers diminish near-wall concentration of platelets in microchannel blood flow

    PubMed Central

    Zhao, R.; Marhefka, J.N.; Antaki, J.F.; Kameneva, M.V.

    2011-01-01

    The accumulation of platelets near the blood vessel wall or artificial surface is an important factor in the cascade of events responsible for coagulation and/or thrombosis. In small blood vessels and flow channels this phenomenon has been attributed to the blood phase separation that creates a red blood cell (RBC)-poor layer near the wall. We hypothesized that blood soluble drag-reducing polymers (DRP), which were previously shown to lessen the near-wall RBC depletion layer in small channels, may consequently reduce the near-wall platelet excess. This study investigated the effects of DRP on the lateral distribution of platelet-sized fluorescent particles (diam. = 2 µm, 2.5 × 108/ml) in a glass square microchannel (width and depth = 100 µm). RBC suspensions in PBS were mixed with particles and driven through the microchannel at flow rates of 6–18 ml/h with and without added DRP (10 ppm of PEO, MW = 4500 kDa). Microscopic flow visualization revealed an elevated concentration of particles in the near-wall region for the control samples at all tested flow rates (between 2.4 ± 0.8 times at 6 ml/h and 3.3 ± 0.3 times at 18 ml/h). The addition of a minute concentration of DRP virtually eliminated the near-wall particle excess, effectively resulting in their even distribution across the channel, suggesting a potentially significant role of DRP in managing and mitigating thrombosis. PMID:21084744

  17. Homocysteine is a novel risk factor for suboptimal response of blood platelets to acetylsalicylic acid in coronary artery disease: a randomized multicenter study.

    PubMed

    Karolczak, Kamil; Kamysz, Wojciech; Karafova, Anna; Drzewoski, Jozef; Watala, Cezary

    2013-08-01

    The incomplete inhibition of platelet function by acetylsalicylic acid (ASA), despite the patients are receiving therapeutic doses of the drug ('aspirin-resistance'), is caused by numbers of risk factors. In this study we verified the idea that plasma homocysteine (Hcy) contributes to 'aspirin-resistance' in patients with coronary artery disease (CAD) and with or without type 2 diabetes mellitus (T2DM). A cross-designed randomized controlled intervention study has been performed (126 CAD pts incl. 26 with T2DM) to determine whether increasing ASA dose from 75mg to 150mg daily may result in the increased antiplatelet effect, in the course of four-week treatment. Platelet response to collagen (coll) or arachidonic acid (AA) was monitored with whole blood aggregometry, plasma thromboxane (Tx), and Hcy levels were determined immunochemically. The ASA-mediated reductions in platelet response to coll (by 12±3%) or AA (by 10±3%) and in plasma Tx (by 20±9%; p<0.02 or less) were significantly greater for higher ASA dose and significantly correlated with plasma Hcy, which was significantly lower in "good" ASA responders compared to "poor" responders (p<0.001). Higher plasma Hcy appeared a significant risk factor for blood platelet refractoriness to low ASA dose (OR=1.11; ±95%CI: 1.02-1.20, p<0.02, adjusted to age, sex and CAD risk factors). Hcy diminished in vitro antiplatelet effect of low ASA concentration and augmented platelet aggregation (by up to 62% (p<0.005) for coll and up to 15% (p<0.005) for AA), whereas its acetyl derivative acted oppositely. Otherwise, Hcy intensified antiplatelet action of high ASA. Hyperhomocysteinaemia may be a novel risk factor for the suppressed blood platelet response to ASA, and homocysteine may act as a specific sensitizer of blood platelets to some agonists. While homocysteine per se acts as a proaggregatory agent to blood platelets, its acetylated form is able to reverse this effect. Thus, these findings reveal a possibly new

  18. Neonatal Transfusion Practice: When do Neonates Need Red Blood Cells or Platelets?

    PubMed

    Del Vecchio, Antonio; Franco, Caterina; Petrillo, Flavia; D'Amato, Gabriele

    2016-09-01

    Based on small studies and not on statistically valid clinical trials, guidelines for neonatal transfusions remain controversial and practices vary greatly. Premature infants and critically ill neonates in the neonatal intensive care unit (NICU) often require blood transfusions and extremely preterm neonates receive at least one red blood cell transfusion during their hospital stay. Transfusions to neonates convey both benefits and risks and consequently it is imperative to establish specific guidelines to improve practice and avoid unnecessary transfusions. Appropriate and lifesaving platelet transfusion in thrombocytopenic bleeding neonates pertains to 2% of all neonates in NICUs. Inversely, 98% of platelet transfusions are given prophylactically, in the absence of bleeding, with the assumption that this reduces the risk of a serious hemorrhage. To date, no evidence base is available for assigning a platelet transfusion trigger to NICU patients. Each NICU should approve specific guidelines that best suit its local clinical practice. Therefore, whatever guidelines are chosen in deciding when to transfuse, what is most important is to adhere strictly to the guidelines adopted, thus limiting unnecessary transfusions that convey no benefits and carry both known and unknown risks. PMID:27603540

  19. CD31 expression on peripheral blood stem cells predicts both early neutrophil and platelet engraftments.

    PubMed

    Donmez, Ayhan; Tombuloglu, Murat; Gulbahar, Okan; Arik, Bahar; Cagirgan, Seckin; Vural, Filiz; Gokmen, Nihal

    2013-10-01

    No detailed information currently exists about the immune phenotypic profiles of peripheral blood stem cells (PBSCs) obtained by different mobilization regimens. The effects of these profiles on the outcome of transplantation are largely unknown. In this prospective study, the surface immune phenotypic features (CD11a, CD18, CD31, CD38, CD44, CD62e, CD62L, CD90, CD117, CD135 and CD184 expression) of sorted PBSCs that had been mobilized by growth factor with (group I and group II) or without (group III) disease-specific chemotherapies were investigated. The immune phenotypic features on mobilized PBSCs in groups I, II and III were not significantly different. The CD31 (platelet endothelial cell adhesion molecule-1) positivity ratio on PBSCs inversely correlated with both the duration of neutrophil (r=-0.32, p=0.03) and platelet (r=-0.36, p=0.02) engraftment. No relationship was found between the engraftment (neutrophil and platelet) durations and CD184 (chemokine receptor CXC motif receptor 4 [CXCR4]) expression on PBSCs. We demonstrated that the surface immune phenotypic profiles on PBSCs obtained by several mobilization regimens were not different. To our knowledge, this is the first study to demonstrate that CD31 expression on human PBSCs may positively affect both neutrophil and platelet engraftment. Contrary to our expectations, CD184 (CXCR4) expression on PBSCs has no effect on neutrophil or platelet engraftment. Considered together, our results suggest that additional surface antigens (such as CD31) may be more effective in the homing process. PMID:24025427

  20. A multiple time stepping algorithm for efficient multiscale modeling of platelets flowing in blood plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Zhang, Na; Deng, Yuefan; Bluestein, Danny

    2015-03-01

    We developed a multiple time-stepping (MTS) algorithm for multiscale modeling of the dynamics of platelets flowing in viscous blood plasma. This MTS algorithm improves considerably the computational efficiency without significant loss of accuracy. This study of the dynamic properties of flowing platelets employs a combination of the dissipative particle dynamics (DPD) and the coarse-grained molecular dynamics (CGMD) methods to describe the dynamic microstructures of deformable platelets in response to extracellular flow-induced stresses. The disparate spatial scales between the two methods are handled by a hybrid force field interface. However, the disparity in temporal scales between the DPD and CGMD that requires time stepping at microseconds and nanoseconds respectively, represents a computational challenge that may become prohibitive. Classical MTS algorithms manage to improve computing efficiency by multi-stepping within DPD or CGMD for up to one order of magnitude of scale differential. In order to handle 3-4 orders of magnitude disparity in the temporal scales between DPD and CGMD, we introduce a new MTS scheme hybridizing DPD and CGMD by utilizing four different time stepping sizes. We advance the fluid system at the largest time step, the fluid-platelet interface at a middle timestep size, and the nonbonded and bonded potentials of the platelet structural system at two smallest timestep sizes. Additionally, we introduce parameters to study the relationship of accuracy versus computational complexities. The numerical experiments demonstrated 3000x reduction in computing time over standard MTS methods for solving the multiscale model. This MTS algorithm establishes a computationally feasible approach for solving a particle-based system at multiple scales for performing efficient multiscale simulations.

  1. A Multiple Time Stepping Algorithm for Efficient Multiscale Modeling of Platelets Flowing in Blood Plasma

    PubMed Central

    Zhang, Peng; Zhang, Na; Deng, Yuefan; Bluestein, Danny

    2015-01-01

    We developed a multiple time-stepping (MTS) algorithm for multiscale modeling of the dynamics of platelets flowing in viscous blood plasma. This MTS algorithm improves considerably the computational efficiency without significant loss of accuracy. This study of the dynamic properties of flowing platelets employs a combination of the dissipative particle dynamics (DPD) and the coarse-grained molecular dynamics (CGMD) methods to describe the dynamic microstructures of deformable platelets in response to extracellular flow-induced stresses. The disparate spatial scales between the two methods are handled by a hybrid force field interface. However, the disparity in temporal scales between the DPD and CGMD that requires time stepping at microseconds and nanoseconds respectively, represents a computational challenge that may become prohibitive. Classical MTS algorithms manage to improve computing efficiency by multi-stepping within DPD or CGMD for up to one order of magnitude of scale differential. In order to handle 3–4 orders of magnitude disparity in the temporal scales between DPD and CGMD, we introduce a new MTS scheme hybridizing DPD and CGMD by utilizing four different time stepping sizes. We advance the fluid system at the largest time step, the fluid-platelet interface at a middle timestep size, and the nonbonded and bonded potentials of the platelet structural system at two smallest timestep sizes. Additionally, we introduce parameters to study the relationship of accuracy versus computational complexities. The numerical experiments demonstrated 3000x reduction in computing time over standard MTS methods for solving the multiscale model. This MTS algorithm establishes a computationally feasible approach for solving a particle-based system at multiple scales for performing efficient multiscale simulations. PMID:25641983

  2. Circulating primers enhance platelet function and induce resistance to antiplatelet therapy

    PubMed Central

    Blair, T A; Moore, S F; Hers, I

    2015-01-01

    Background Aspirin and P2Y12 antagonists are antiplatelet compounds that are used clinically in patients with thrombosis. However, some patients are ‘resistant’ to antiplatelet therapy, which increases their risk of developing acute coronary syndromes. These patients often present with an underlying condition that is associated with altered levels of circulating platelet primers and platelet hyperactivity. Platelet primers cannot stimulate platelet activation, but, in combination with physiologic stimuli, significantly enhance platelet function. Objectives To explore the role of platelet primers in resistance to antiplatelet therapy, and to evaluate whether phosphoinositide 3-kinase (PI3K) contributes to this process. Methods and Results We used platelet aggregation, thromboxane A2 production and ex vivo thrombus formation as functional readouts of platelet activity. Platelets were treated with the potent P2Y12 inhibitor AR-C66096, aspirin, or a combination of both, in the presence or absence of the platelet primers insulin-like growth factor-1 (IGF-1) and thrombopoietin (TPO), or the Gz-coupled receptor ligand epinephrine. We found that platelet primers largely overcame the inhibitory effects of antiplatelet compounds on platelet functional responses. IGF-1-mediated and TPO-mediated, but not epinephrine-mediated, enhancements in the presence of antiplatelet drugs were blocked by the PI3K inhibitors wortmannin and LY294002. Conclusions These results demonstrate that platelet primers can contribute to antiplatelet resistance. Furthermore, our data demonstrate that there are PI3K-dependent and PI3K-independent mechanisms driving primer-mediated resistance to antiplatelet therapy. PMID:26039631

  3. Complement Activation in Trauma Patients Alters Platelet Function.

    PubMed

    Atefi, Gelareh; Aisiku, Omozuanvbo; Shapiro, Nathan; Hauser, Carl; Dalle Lucca, Jurandir; Flaumenhaft, Robert; Tsokos, George C

    2016-09-01

    Trauma remains the main cause of death for both civilians and those in uniform. Trauma-associated coagulopathy is a complex process involving inflammation, coagulation, and platelet dysfunction. It is unknown whether activation of complement, which occurs invariably in trauma patients, is involved in the expression of trauma-associated coagulopathy. We designed a prospective study in which we enrolled 40 trauma patients and 30 healthy donors upon arrival to the emergency department of BIDMC. Platelets from healthy individuals were incubated with sera from trauma patients and their responsiveness to a thrombin receptor-activating peptide was measured using aggregometry. Complement deposition on platelets from trauma patients was measured by flow cytometry. Normal platelets displayed hypoactivity after incubation with trauma sera even though exposure to trauma sera resulted in increased agonist-induced calcium flux. Depletion of complement from sera further blocked activation of hypoactive platelets. Conversely, complement activation increased aggregation of platelets. Platelets from trauma patients were found to have significantly higher amounts of C3a and C4d on their surface compared with platelets from controls. Depletion of complement (C4d, C3a) reversed the ability of trauma sera to augment agonist-induced calcium flux in donor platelets. Our data indicate that complement enhances platelet aggregation. Despite its complement content, trauma sera render platelets hypoactive and complement depletion further blocks activation of hypoactive platelets. The defect in platelet activation induced by trauma sera is distal to receptor activation since agonist-induced Ca2+ flux is elevated in the presence of trauma sera owing to complement deposition. PMID:27355402

  4. Platelet-rich plasma does not decrease blood loss in total knee arthroplasty.

    PubMed

    Tingstad, Edwin M; Bratt, Sarah N; Hildenbrand, Kasee J; O'Malley, Brittany A; Mitchell, Elisabeth R; Gaddis, Corinne E; Jacobson, Charles A

    2015-05-01

    This study was designed to assess the use of platelet-rich plasma (PRP) during primary total knee arthroplasty (TKA). The authors hypothesized that this would result in less blood loss and greater hemoglobin and hematocrit levels at discharge and would potentially decrease the length of hospital stay. Leukocyte rich PRP was used during the procedure and at wound closure. Two surgeons performed all procedures in a similar fashion. Two different TKA implants were used. Each surgeon used the same implant throughout the study. A limited medial parapatellar approach was used and drains were used at closure. No tranexamic acid preparations were used. Continuous passive motion machines were used in all patients during their hospital stay. A total of 102 consecutive TKAs were performed. The study group (n=46) consecutively received the PRP injections during the TKA, whereas the control group (n=47) did not. Hemoglobin and hematocrit levels were obtained pre- and postoperatively. Estimated blood loss was recorded during surgery, and the auto-collection reinfusion drain system output was measured. The length of hospital stay was collected and recorded. The study showed that hemoglobin and hematocrit levels were not different when comparing study and control groups. Age and sex differences were insignificant. Finally, no statistical difference was seen for the estimated blood loss and hospital stay between the 2 groups. Platelet-rich plasma use during TKA does not decrease hospital stay or reduce estimated blood loss in the perioperative period. PMID:25970373

  5. [Analysis of platelet-derived factors that modulate functions of polymorphonuclear leukocytes].

    PubMed

    Sasada, M; Asagoe, K

    1994-04-01

    Interactions between platelets and polymorphonuclear leukocytes (PMN) modulate their functions and play a role in the development of pathogenesis of some disease. Platelets secret various kinds of factors that affect PMN functions. They seemed to have important role in vivo, but little has been elucidated on exact mechanism of action and physiological meaning of each factor in relation to PMN functions. We studied the effects of platelets and released substances from activated platelets on the functions of PMN. Results were as follows. 1) Platelets enhanced bactericidal activities of PMN against E.coli. 2) Platelets had effects on the generation of superoxide anion (O2-) of PMN. Their effects were quite different according to the assay condition of PMN, that is, platelets inhibited O2- generation when PMN were at rest or stimulated slightly and they enhanced O2-generation of PMN that were stimulated with optimal condition. 3) Thrombin-activated platelets and their supernatant elicited a transient elevation of [Ca2] of PMN. The activity of the supernatant decreased by treating with hexokinase that decomposed ATP. Further treatment with trypsin abolished its activity almost completely. Considering with our additional experiments, factors that induced [Ca2+] elevation of PMN were ATP, beta-thromboglobulin and some trypsin-sensitive factor(s). 4) Supernatant of thrombin-activated platelets decreased random migration and chemokinesis of PMN. PMID:8028184

  6. Alterations in bovine platelet function and acute phase proteins induced by Pasteurella haemolytica A1.

    PubMed Central

    Cheryk, L A; Hooper-McGrevy, K E; Gentry, P A

    1998-01-01

    Platelet function was assessed by aggregometry in 10 Holstein calves before and after exposure to Pasteurella haemolytica (biotype A, serotype 1) by intrabronchial challenge. At 24 h after exposure the platelets had become more reactive to stimulation with known platelet agonists such as adenosine diphosphate (ADP) and platelet-activating factor (PAF) and the platelet aggregates that formed were more resistant to disaggregation. The activation of platelets was an early response in the challenged calves as platelet function had returned to pretreatment levels 72 h after exposure to the bacteria while the acute phase reactant proteins, haptoglobin and fibrinogen, were approaching their peak values and alpha 2-macroglobulin levels had also risen significantly (P < 0.05) at this time. The plasma levels of these proteins were still elevated and albumin levels were depressed 6 d post-treatment. At post-mortem all calves exhibited pneumonic tissue damage. When P. haemolytica leukotoxin was added directly to bovine platelet suspensions both spontaneous aggregation and an increase in the aggregation response to ADP and PAF stimulation were observed. The morphological appearance of the platelet aggregates exhibited the typical pattern for bovine platelets with 2 distinct zones of cells being visible within each aggregate. One zone contained platelets in which the cytoplasmic granules were still evident and the other zone contained irregularly shaped platelets devoid of granular content. In the latter zone, discrete gaps, or pores, were evident in the plasma membrane of numerous platelets. This pore formation is characteristic of leukotoxin action and is not observed in ADP or PAF induced aggregates. Images Figure 2. PMID:9442932

  7. Platelet C1- inhibitor. A secreted alpha-granule protein.

    PubMed Central

    Schmaier, A H; Smith, P M; Colman, R W

    1985-01-01

    In order to characterize which proteins of the contact phase of coagulation interact with platelets, human platelets were studied immunochemically and functionally to determine if they contain C1- inhibitor. By means of monospecific antibody to C1- inhibitor, a competitive enzyme-linked immunosorbent assay (CELISA) was developed to measure directly platelet C1- inhibitor. With the CELISA, from 33 to 115 ng of C1- inhibitor antigen per 10(8) platelets from 15 normal donors was quantified in lysates of washed human platelets solubilized in nonionic detergent. The mean concentration in 10(8) platelets was 62 +/- 33 ng (SD). Plasma C1- inhibitor either in the platelet suspension medium or on the surface of the platelets could account for only from 6.5 to 16% of the total antigen measured in the solubilized platelets. Upon functional studies, platelets contained 84 +/- 36 ng (SD) of C1- inhibitor activity in 10(8) platelets. As assessed by the CELISA, platelet C1- inhibitor antigen was immunochemically identical to plasma and purified C1- inhibitor. In contrast, the mean concentration of platelet C1- inhibitor antigen in platelets from four patients with classical hereditary angioedema was 8.3 ng/10(8) platelets (range, 5.3 to 11.3 ng/10(8) platelets). 25 and 31% of the total platelet C1- inhibitor was secreted without cell lysis from normal platelets after exposure to collagen (20 micrograms/ml) and thrombin (1 U/ml), respectively, and this secretion was blocked by metabolic inhibitors. Platelet subcellular fractionation showed that platelet C1- inhibitor resided mostly in alpha-granules, similar to the location of platelet fibrinogen. Thus, human platelets contained C1- inhibitor, which became available by platelet secretion. The identification of platelet C1- inhibitor suggests that platelets may modulate the activation of the proteins of early blood coagulation and the classical complement pathways. Images PMID:3965505

  8. Blood

    MedlinePlus

    ... fight infection and are part of your body's defense system. Platelets help blood to clot when you have a cut or wound. Bone marrow, the spongy material inside your bones, makes new blood cells. Blood cells ...

  9. Most Recent Evidence Behind Aggregometry and Genotyping Methods as Platelet Function Testing for Tailored Anti-Platelet Treatment Among PCI Patients.

    PubMed

    Gajda, Sylwia N; Kołtowski, Łukasz; Tomaniak, Mariusz

    2015-01-01

    Aggregometry and genotyping are methods of platelet function testing, which can be beneficial for high-risk patients undergoing invasive cardiac procedures. An optimal level of platelet reactivity (PR) should be maintained. There are discrepancies between individuals and their response to clopidogrel, accounting for the incidence of poor responders from 5% to 44%. This phenomenon predisposes the patients to increased risk of ischaemic events and thereby overall poorer clinical outcome. Prasugrel and tricagrelor are newer without genetic correlation to their action, however associated with increased bleeding risk. Aggregometry methods assess platelet reactivity at the exact moment of blood sampling. They reflect "phenotype" of the patient and vary after drug administration or dose change. The most popular tests are Light Transmission Aggregometry, Vasodilator-Stimulated Protein, VerifyNow, Multiple Electrode Aggregometry and Thrombelastography. There is proven genetic correlation between some cytochrome enzymes on clopidogrel response. The most widely tested is gene CYP2C19, which produces the enzyme transforming clopidogrel into an active metabolite. The CYP2C19*2 allele carriers have higher PR which can result in more thrombotic events. The manuscript shows the most recent evidence behind platelet function testing. Aggregometry is shown to be beneficial in 5 trials and 1 meta-analysis, while one paper was of different opinion. Ten studies show a positive clinical effect of genotyping on patients' outcome, while one does not support it. The best method of identifying high-risk individuals could be both methods and personalisation of antiplatelet therapy may decrease adverse ischaemic outcomes. PMID:26469115

  10. Targeted drug delivery to circulating tumor cells via platelet membrane-functionalized particles.

    PubMed

    Li, Jiahe; Ai, Yiwei; Wang, Lihua; Bu, Pengcheng; Sharkey, Charles C; Wu, Qianhui; Wun, Brittany; Roy, Sweta; Shen, Xiling; King, Michael R

    2016-01-01

    Circulating tumor cells (CTCs) are responsible for metastases in distant organs via hematogenous dissemination. Fundamental studies in the past decade have suggested that neutralization of CTCs in circulation could represent an effective strategy to prevent metastasis. Current paradigms of targeted drug delivery into a solid tumor largely fall into two main categories: unique cancer markers (e.g. overexpression of surface receptors) and tumor-specific microenvironment (e.g. low pH, hypoxia, etc.). While relying on a surface receptor to target CTCs can be greatly challenged by cancer heterogeneity, targeting of tumor microenvironments has the advantage of recognizing a broader spectrum of cancer cells regardless of genetic differences or tumor types. The blood circulation, however, where CTCs transit through, lacks the same tumor microenvironment as that found in a solid tumor. In this study, a unique "microenvironment" was confirmed upon introduction of cancer cells of different types into circulation where activated platelets and fibrin were physically associated with blood-borne cancer cells. Inspired by this observation, synthetic silica particles were functionalized with activated platelet membrane along with surface conjugation of tumor-specific apoptosis-inducing ligand cytokine, TRAIL. Biomimetic synthetic particles incorporated into CTC-associated micro-thrombi in lung vasculature and dramatically decreased lung metastases in a mouse breast cancer metastasis model. Our results demonstrate a "Trojan Horse" strategy of neutralizing CTCs to attenuate metastasis. PMID:26519648

  11. Platelet function and activation in Cavalier King Charles Spaniels with subclinical chronic valvular heart disease.

    PubMed

    Tong, Linda J; Hosgood, Giselle L; French, Anne T; Irwin, Peter J; Shiel, Robert E

    2016-08-01

    OBJECTIVE To assess platelet closure time (CT), mean platelet component (MPC) concentration, and platelet component distribution width (PCDW) in dogs with subclinical chronic valvular heart disease. ANIMALS 89 Cavalier King Charles Spaniels (CKCSs) and 39 control dogs (not CKCSs). PROCEDURES Platelet count, MPC concentration, PCDW, and Hct were measured by use of a hematology analyzer, and CT was measured by use of a platelet function analyzer. Murmur grade and echocardiographic variables (mitral valve regurgitant jet size relative to left atrial area, left atrial-to-aortic diameter ratio, and left ventricular internal dimensions) were recorded. Associations between explanatory variables (sex, age, murmur grade, echocardiographic variables, platelet count, and Hct) and outcomes (CT, MPC concentration, and PCDW) were examined by use of multivariate regression models. RESULTS A model with 5 variables best explained variation in CT (R(2), 0.74), with > 60% of the variance of CT explained by mitral valve regurgitant jet size. The model of best fit to explain variation in MPC concentration included only platelet count (R(2), 0.24). The model of best fit to explain variation in PCDW included platelet count and sex (R(2), 0.25). CONCLUSIONS AND CLINICAL RELEVANCE In this study, a significant effect of mitral valve regurgitant jet size on CT was consistent with platelet dysfunction. However, platelet activation, as assessed on the basis of the MPC concentration and PCDW, was not a feature of subclinical chronic valvular heart disease in CKCSs. PMID:27463549

  12. Platelet aggregation test

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003669.htm Platelet aggregation test To use the sharing features on this page, please enable JavaScript. The platelet aggregation blood test checks how well platelets , a ...

  13. Impact of Aspirin and Clopidogrel Interruption on Platelet Function in Patients Undergoing Major Vascular Surgery

    PubMed Central

    Le Manach, Yannick; Kahn, David; Bachelot-Loza, Christilla; Le Sache, Frederic; Smadja, David M.; Remones, Veronique; Loriot, Marie-Anne; Coriat, Pierre; Gaussem, Pascale

    2014-01-01

    Aims To investigate functional platelet recovery after preoperative withdrawal of aspirin and clopidogrel and platelet function 5 days after treatment resumption. Methods/Results We conducted an observational study, which prospectively included consecutive patients taking aspirin, taking clopidogrel, and untreated controls (15 patients in each group). The antiplatelet drugs were withdrawn five days before surgery (baseline) and were reintroduced two days after surgery. Platelet function was evaluated by optical aggregation in the presence of collagen, arachidonic acid (aspirin) and ADP (clopidogrel) and by VASP assay (clopidogrel). Platelet-leukocyte complex (PLC) level was quantified at each time-point. At baseline, platelet function was efficiently inhibited by aspirin and had recovered fully in most patients 5 days after drug withdrawal. PLC levels five days after aspirin reintroduction were similar to baseline (+4±10%; p = 0.16), in line with an effective platelet inhibition. Chronic clopidogrel treatment was associated with variable platelet inhibition and its withdrawal led to variable functional recovery. PLC levels were significantly increased five days after clopidogrel reintroduction (+10±15%; p = 0.02), compared to baseline. Conclusions Aspirin withdrawal 5 days before high-bleeding-risk procedures was associated with functional platelet recovery, and its reintroduction two days after surgery restored antiplaletet efficacy five days later. This was not the case of clopidogrel, and further work is therefore needed to define its optimal perioperative management. PMID:25141121

  14. Flow cytometry analysis of platelet P-selectin expression in whole blood--methodological considerations.

    PubMed

    Ritchie, J L; Alexander, H D; Rea, I M

    2000-12-01

    P-selectin is an adhesion molecule found in the alpha granules of platelets. Activation occurs in response to a range of inflammatory and thrombotic agents resulting in rapid up-regulation. Flow cytometry methods have recently been described for the analysis of platelet P-selectin expression in whole blood. While introducing these methods into our laboratory it was noted that expression could be stimulated, in vitro, in a number of ways. This study shows that red cell lysis, the anticoagulant K3 EDTA and the time elapse between blood collection and antibody labelling had statistically significant effects on P-selectin expression. Post-labelling fixation, with CellFIX, caused no significant effect. We conclude that blood for P-selectin analysis should be collected in sodium citrate and that red cell lysis and centrifugation should be avoided. When comparing samples, the time between collection and labelling should be standardized. The relatively high CV for the assay indicates that all samples should be labelled and analysed in duplicate with the mean level reported. PMID:11318803

  15. The Blood Group A Genotype Determines the Level of Expression of the Blood Group A on Platelets But Not the Anti-B Isotiter

    PubMed Central

    Lehner, Barbara; Eichelberger, Beate; Jungbauer, Christof; Panzer, Simon

    2015-01-01

    Summary Background The extent of expression of the blood group A on platelets is controversial. Further, the relation between platelets' blood group A expression and the titers of isoagglutinins has not been thoroughly investigated, so far. Methods We evaluated the relation between the genotype with platelets' blood group A and H expression estimated by flow cytometry and the titers of isoagglutinins. Results The A expression varied between genotypes and within genotypes. However, the expression in A1 was stronger than in all other genotypes (p < 0.0001). An overlap of expression levels was apparent between homozygous A1A1 and heterozygous A1 individuals. Still, The A1A1 genotype is associated with a particularly high antigen expression (p = 0.009). Platelets' A expression in A2 versus blood group O donors was also significant (p = 0.007), but there was again an overlap of expression. The secretor status had only little influence on the expression (p = 0.18). Also, isoagglutinin titers were not associated with genotypes. Conclusion: To distinguish between A1 and A2 donors may reduce incompatible platelet transfusions and therefore be favorable on platelet transfusion increment. Clinical data are needed to support this notion. PMID:26733767

  16. cADP-ribose formation by blood platelets is not responsible for intracellular calcium mobilization.

    PubMed Central

    Ohlmann, P; Leray, C; Ravanat, C; Hallia, A; Cassel, D; Cazenave, J P; Gachet, C

    1998-01-01

    Human platelet CD38 is a multifunctional ectoenzyme catalysing the synthesis and hydrolysis of cADP-ribose (cADPR), a recently identified calcium-mobilizing agent that acts independently of D-myo-inositol 1,4,5-trisphosphate and is known to be expressed by human platelets. The present work shows that ADP-ribosyl cyclase activity is exclusively a membrane activity, of which the major part is located in plasma membranes and a small part in internal membranes. In broken cells, cyclase activity was insensitive to the presence of calcium and was not modulated by agonists such as thrombin or ADP, whereas in intact cells thrombin increased cADPR formation by 30%, an effect due to fusion of granules with the plasma membrane. In order to assess the role of cADPR as a calcium-mobilizing agent, vesicles were prepared from internal membranes and loaded with 45CaCl2. These vesicles were efficiently discharged by IP3 in a dose-dependent manner, but were not responsive to cADPR or ryanodine in the presence or absence of calmodulin. Thus cADPR is unlikely to play a role in intracellular calcium release in human blood platelets. PMID:9531481

  17. The increased level of COX-dependent arachidonic acid metabolism in blood platelets from secondary progressive multiple sclerosis patients.

    PubMed

    Morel, Agnieszka; Miller, Elzbieta; Bijak, Michal; Saluk, Joanna

    2016-09-01

    Platelet activation is increasingly postulated as a possible component of the pathogenesis of multiple sclerosis (MS), especially due to the increased risk of cardiovascular events in MS. Arachidonic acid cascade metabolized by cyclooxygenase (COX) is a key pathway of platelet activation. The aim of our study was to investigate the COX-dependent arachidonic acid metabolic pathway in blood platelets from secondary progressive multiple sclerosis (SP MS) patients. The blood samples were obtained from 50 patients (man n = 22; female n = 28), suffering from SP MS, diagnosed according to the revised McDonald criteria. Platelet aggregation was measured in platelet-rich plasma after arachidonic acid stimulation. The level of COX activity and thromboxane B2 concentration were determined by ELISA method. Lipid peroxidation was assessed by measuring the level of malondialdehyde. The results were compared with a control group of healthy volunteers. We found that blood platelets obtained from SP MS patients were more sensitive to arachidonic acid and their response measured as platelet aggregation was stronger (about 14 %) relative to control. We also observed a significantly increased activity of COX (about 40 %) and synthesis of thromboxane B2 (about 113 %). The generation of malondialdehyde as a marker of lipid peroxidation was about 10 % higher in SP MS than in control. Cyclooxygenase-dependent arachidonic acid metabolism is significantly increased in blood platelets of patients with SP MS. Future clinical studies are required to recommend the use of low-dose aspirin, and possibly other COX inhibitors in the prevention of cardiovascular risk in MS. PMID:27507559

  18. 2E4 (Kaptin): A novel actin-associated protein from human blood platelets found in lamellipodia and the tips of the stereocilia of the inner ear

    PubMed Central

    Bearer, Elaine L.; Abraham, Manoj T.

    2010-01-01

    Actin – 2E4/kaptin – platelet activation – stereocilia – sensory epithelium Platelet activation, crucial for hemostasis, requires actin polymerization, yet the molecular mechanisms by which localized actin polymerization is mediated are not clear. Here we report the characterization of a novel actin-binding protein. 2E4, originally isolated from human blood platelets and likely to be involved in the actin rearrangements occurring during activation. 2E4 binds to filamentous (F)-actin by F-actin affinity chromatography and is eluted from F-actin affinity columns and extracted from cells with ATP. Its presence at the leading edge of platelets spread on glass and in the lamellipodia of motile fibroblasts suggests a role in actin dynamics. Using localization to obtain clues about function, we stained the sensory epithelium of the embryonic inner car to determine whether 2E4 is at the barbed end of actin filaments during their elongation. Indeed, 2E4 was present at the tips of the elongating stereocilium. 2E4 is novel by DNA sequence and has no identifiable structural motifs. Its unusual amino acid sequence, its ATP-sensitive actin association and its location at sites of actin polymerization in cells suggest 2E4 plays a unique role in the actin rearrangements that accompany platelet activation and stereocilia formation. PMID:10099934

  19. Wiskott-Aldrich Syndrome Presenting with JMML-Like Blood Picture and Normal Sized Platelets

    PubMed Central

    Patil, Rajesh B.; Shanmukhaiah, Chandrakala; Bamborde, Shailesh; Wasekar, Nilesh; Toshniwal, Manoj; Mohite, Aniket; Patil, Vinod

    2016-01-01

    Objective. The aim of this paper is to report the case of Wiskott-Aldrich syndrome (WAS) that presented with unusual laboratory features. Clinical Presentation and Intervention. Male neonate admitted with symptoms related to thrombocytopenia, whose initial diagnosis was considered as neonatal alloimmune thrombocytopenia and JMML (juvenile myelomonocytic leukemia) but subsequently diagnosis was confirmed as WAS. Conclusion. This case shows that a suspicion of WAS is warranted in the setting of neonatal thrombocytopenia with JMML-like blood picture and normal sized platelets. PMID:27340577

  20. An overview of platelet indices for evaluating platelet function in children with scorpion envenomation

    PubMed Central

    Konca, Capan; Tekin, Mehmet; Colak, Pinar; Uckardes, Fatih; Turgut, Mehmet

    2014-01-01

    The aim of this study was to assess the correlation between platelet indices and scorpion envenomations (SE). Medical records of 76 children who were hospitalised for scorpion stings in the paediatric intensive care unit (PICU) between February 2013 and November 2013, and 55 healthy children who were similar to the patient group in terms of age and sex, were analysed retrospectively. The leucocyte (WBC), thrombocyte (PLT), plateletcrit (PCT), platelet distribution width (PDW) and mean platelet volume (MPV) values of the 76 children with SE were recorded. These values were compared with the healthy control group. Significantly higher WBC and PDW values were noted in patients with SE in comparison to the controls. Patients with SE had significantly lower mean MPV values compared to the healthy controls (9.03 ± 1.26 compared to 10.43 ± 1.44 fL, respectively; p < 0.001). Although the mean platelet count was slightly elevated in the SE group, no statistically significant difference existed between the two groups (p = 0.097). Furthermore, the mean PCT values in the SE group compared to the control group were slightly decreased, but this decrease was not statistically significant (p = 0.141). A significant inverse correlation existed between the MPV values and the WBC (r = -0.450, p < 0.01) and PLT counts (r = -0.420, p < 0.01). The PLT values were significantly correlated with the PCT values (r = 0.687, p < 0.01). This study demonstrated that SE may lead to several alterations in platelet indices. Significantly lower values of MPV and higher values of PDW were detected in SE patients. However, the increase in the platelet counts and the decrease in the PCT values were not significant. PMID:26417303

  1. An overview of platelet indices for evaluating platelet function in children with scorpion envenomation.

    PubMed

    Konca, Capan; Tekin, Mehmet; Colak, Pinar; Uckardes, Fatih; Turgut, Mehmet

    2014-01-01

    The aim of this study was to assess the correlation between platelet indices and scorpion envenomations (SE). Medical records of 76 children who were hospitalised for scorpion stings in the paediatric intensive care unit (PICU) between February 2013 and November 2013, and 55 healthy children who were similar to the patient group in terms of age and sex, were analysed retrospectively. The leucocyte (WBC), thrombocyte (PLT), plateletcrit (PCT), platelet distribution width (PDW) and mean platelet volume (MPV) values of the 76 children with SE were recorded. These values were compared with the healthy control group. Significantly higher WBC and PDW values were noted in patients with SE in comparison to the controls. Patients with SE had significantly lower mean MPV values compared to the healthy controls (9.03 ± 1.26 compared to 10.43 ± 1.44 fL, respectively; p < 0.001). Although the mean platelet count was slightly elevated in the SE group, no statistically significant difference existed between the two groups (p = 0.097). Furthermore, the mean PCT values in the SE group compared to the control group were slightly decreased, but this decrease was not statistically significant (p = 0.141). A significant inverse correlation existed between the MPV values and the WBC (r = -0.450, p < 0.01) and PLT counts (r = -0.420, p < 0.01). The PLT values were significantly correlated with the PCT values (r = 0.687, p < 0.01). This study demonstrated that SE may lead to several alterations in platelet indices. Significantly lower values of MPV and higher values of PDW were detected in SE patients. However, the increase in the platelet counts and the decrease in the PCT values were not significant. PMID:26417303

  2. Platelets and their interactions with other immune cells

    PubMed Central

    Lam, Fong W.; Vijayan, K. Vinod; Rumbaut, Rolando E.

    2015-01-01

    Platelets are anucleate blood cells, long known to be critically involved in hemostasis and thrombosis. In addition to their role in blood clots, increasing evidence reveals significant roles for platelets in inflammation and immunity. However, the notion that platelets represent immune cells is not broadly recognized in the field of Physiology. This manuscript reviews the role of platelets in inflammation and immune responses, and highlights their interactions with other immune cells, including examples of major functional consequences of these interactions. PMID:26140718

  3. Platelet Immobilization on Supported Phospholipid Bilayers for Single Platelet Studies.

    PubMed

    Uhl, Eva; Donati, Alessia; Reviakine, Ilya

    2016-08-23

    The worldwide cardiovascular disease (CVD) epidemic is of grave concern. A major role in the etiology of CVDs is played by the platelets (thrombocytes). Platelets are anuclear cell fragments circulating in the blood. Their primary function is to catalyze clot formation, limiting traumatic blood loss in the case of injury. The same process leads to thrombosis in the case of CVDs, which are commonly managed with antiplatelet therapy. Platelets also have other, nonhemostatic functions in wound healing, inflammation, and tissue regeneration. They play a role in the early stages of atherosclerosis and the spread of cancer through metastases. Much remains to be learned about the regulation of these diverse platelet functions under physiological and pathological conditions. Breakthroughs in this regard are expected to come from single platelet studies and systems approaches. The immobilization of platelets at surfaces is advantageous for developing such approaches, but platelets are activated when they come in contact with foreign surfaces. In this work, we develop and validate a protocol for immobilizing platelets on supported lipid bilayers without activation due to immobilization. Our protocol can therefore be used for studying platelets with a wide variety of surface-sensitive techniques. PMID:27438059

  4. Platelet Adhesion under Flow

    PubMed Central

    Ruggeri, Zaverio M.

    2011-01-01

    Platelet adhesive mechanisms play a well-defined role in hemostasis and thrombosis, but evidence continues to emerge for a relevant contribution to other pathophysiological processes including inflammation, immune-mediated responses to microbial and viral pathogens, and cancer metastasis. Hemostasis and thrombosis are related aspects of the response to vascular injury, but the former protects from bleeding after trauma while the latter is a disease mechanism. In either situation, adhesive interactions mediated by specific membrane receptors support the initial attachment of single platelets to cellular and extracellular matrix constituents of the vessel wall and tissues. In the subsequent steps of thrombus growth and stabilization, adhesive interactions mediate platelet to platelet cohesion (aggregation) and anchoring to the fibrin clot. A key functional aspect of platelets is their ability to circulate in a quiescent state surveying the integrity of the inner vascular surface, coupled to a prompt reaction wherever alterations are detected. In many respects, therefore, platelet adhesion to vascular wall structures, to one another or to other blood cells are facets of the same fundamental biological process. The adaptation of platelet adhesive functions to the effects of blood flow is the main focus of this review. PMID:19191170

  5. Heparin inhibition of von Willebrand factor-dependent platelet function in vitro and in vivo.

    PubMed Central

    Sobel, M; McNeill, P M; Carlson, P L; Kermode, J C; Adelman, B; Conroy, R; Marques, D

    1991-01-01

    The intravenous administration of heparin to patients before open heart surgery reduced ristocetin cofactor activity by 58% (P less than 0.01, t test), and this impairment of von Willebrand factor-dependent platelet function was closely related to plasma heparin levels (r2 = 0.9), but not to plasma von Willebrand factor (vWF) levels. We hypothesized that heparin may inhibit vWF-dependent platelet hemostatic functions by directly binding vWF in solution and interfering with vWF-GpIb binding. Using the in vitro techniques of ristocetin-induced platelet agglutination, fluorescent flow cytometric measurement of vWF-platelet binding, and conventional radioligand binding assays we observed that heparin inhibited both vWF-dependent platelet function and vWF-platelet binding in a parallel and dose-dependent manner. Heparin also inhibited platelet agglutination induced by bovine vWF and inhibited the binding of human asialo-vWF to platelets in ristocetin-free systems. The inhibitory potency of heparin was not dependent upon its affinity for antithrombin III, but was molecular weight dependent: homogeneous preparations of lower molecular weight were less inhibitory. Heparin impairment of vWF function may explain why some hemorrhagic complications of heparin therapy are not predictable based on techniques for monitoring the conventional anticoagulant effects of heparin. PMID:2022745

  6. Functional validation of platelet-activating factor receptor sites characterized biochemically by a specific and reproducible ( sup 3 H)platelet-activating factor binding in human platelets

    SciTech Connect

    Tahraoui, L.; Floch, A.; Cavero, I. )

    1990-03-01

    In human platelet membranes, (3H)platelet-activating factor(PAF)-C18 binding sites exhibited high affinity (Kd 0.074 +/- 0.005 nM, n = 28 healthy volunteers), saturability, elevated stereoselectivity, marked pharmacological specificity and small intersubject variability. The maximal binding capacity was 215 +/- 12 fmol/mg protein. Saturation of (3H)PAF binding was obtained with 0.3 nM ligand, and its isotherm was compatible with a single class of binding sites. The stereoselectivity for (3H)PAF was clearly indicated by the low displacing potency of enantio-PAF-C16 (the synthetic enantiomer of PAF) that was 5000-fold less potent than PAF. Specific (3H)PAF binding attained 65% with 0.1 nM ligand and was displaced fully not only by cold PAF but also by RP 59227 (Ki = 6.2 +/- 1.3 nM, n = 7), a novel, potent and specific PAF receptor antagonist in a pure enantiomeric form and several other antagonists such as CV-6209, WEB 2086, L-652,731 and BN 52021. Various classical pharmacological agents did not interfere with the (3H)PAF binding. In intact platelets, (3H)PAF binding shared the same properties as those just described for membrane preparations. A functional role for these binding sites was suggested by the high correlation (r = 0.94, P less than .001) between the Ki values for several known PAF antagonists determined in (3H)PAF binding and the IC50 values obtained against PAF-induced aggregation in whole platelets. Thus, the present (3H)PAF binding in human platelet membranes may be a useful pharmacological tool to study possible changes in (3H)PAF binding parameters induced by pathological states for which PAF may be directly or indirectly responsible.

  7. FXIa and platelet polyphosphate as therapeutic targets during human blood clotting on collagen/tissue factor surfaces under flow.

    PubMed

    Zhu, Shu; Travers, Richard J; Morrissey, James H; Diamond, Scott L

    2015-09-17

    Factor XIIa (FXIIa) and factor XIa (FXIa) contribute to thrombosis in animal models, whereas platelet-derived polyphosphate (polyP) may potentiate contact or thrombin-feedback pathways. The significance of these mediators in human blood under thrombotic flow conditions on tissue factor (TF) -bearing surfaces remains inadequately resolved. Human blood (corn trypsin inhibitor treated [4 μg/mL]) was tested by microfluidic assay for clotting on collagen/TF at TF surface concentration ([TF]wall) from ∼0.1 to 2 molecules per μm(2). Anti-FXI antibodies (14E11 and O1A6) or polyP-binding protein (PPXbd) were used to block FXIIa-dependent FXI activation, FXIa-dependent factor IX (FIX) activation, or platelet-derived polyP, respectively. Fibrin formation was sensitive to 14E11 at 0 to 0.1 molecules per µm(2) and sensitive to O1A6 at 0 to 0.2 molecules per µm(2). However, neither antibody reduced fibrin generation at ∼2 molecules per µm(2) when the extrinsic pathway became dominant. Interestingly, PPXbd reduced fibrin generation at low [TF]wall (0.1 molecules per µm(2)) but not at zero or high [TF]wall, suggesting a role for polyP distinct from FXIIa activation and requiring low extrinsic pathway participation. Regardless of [TF]wall, PPXbd enhanced fibrin sensitivity to tissue plasminogen activator and promoted clot retraction during fibrinolysis concomitant with an observed PPXbd-mediated reduction of fibrin fiber diameter. This is the first detection of endogenous polyP function in human blood under thrombotic flow conditions. When triggered by low [TF]wall, thrombosis may be druggable by contact pathway inhibition, although thrombolytic susceptibility may benefit from polyP antagonism regardless of [TF]wall. PMID:26136249

  8. In-line filtration of platelet concentrates obtained with the Omnix blood cell separator.

    PubMed

    Moog, R; Müller, N; Nieper, A

    1995-12-01

    The quality of platelet concentrates (PC) obtained with the blood cell separator Omnix was investigated before and after in-line filtration. PC were filtered 2h (protocol A) and 4 h (protocol B) after the termination of apheresis. Platelet (PLT) yield after filtration was similar in both protocols (median 3.7 vs. 3.4 x 10(11)). Median white blood cell (WBC) contamination after leucocyte depletion was 0.07 x 10(6) (range 0.02-3.27 x 10(6)) in protocol A and 0.06 x 10(6) (range 0.02-2.1 x 10(6)) in protocol B. Glucose, lactate, lactate dehydrogenase, morphology score and pH value were not statistically different before and after filtration in both protocols. We conclude that in-line filtration results in sufficient leucocyte depletion of the PC. The prefiltration storage time did not influence the studied parameters of product quality. PMID:8646295

  9. Tissue augmentation by white blood cell-containing platelet-rich plasma.

    PubMed

    Kawazoe, Takeshi; Kim, Hak Hee

    2012-01-01

    Platelet-rich plasma (PRP) is a matrix of fibrin and platelets that releases cytokines that are important in wound healing. PRP is produced from the patient's blood and therefore has less risk of allergic reaction and infection. We have obtained PRP with an enhanced white blood cell component (W-PRP) by optimizing the centrifugal separation of PRP from plasma. Here we show that injection of W-PRP into the auricle of nude mice gave greater tissue augmentation compared to PRP. Further augmentation occurred when bFGF was added to W-PRP, and there was a significant increase in the number of α-smooth muscle actin-positive cells in mice treated with W-PRP+bFGF. Our results suggest that W-PRP may have value in cosmetic surgery aimed at rejuvenation of wrinkled and sagging skin. W-PRP injection constitutes a new concept in cell transplantation, in which cells required for tissue regeneration are induced by cytokines released from the transplanted cells. PMID:22793069

  10. Platelet aggregability and in vivo platelet deposition in patients with ischemic cerebrovascular disease--evaluation by indium-111-platelet scintigraphy

    SciTech Connect

    Isaka, Y.; Kimura, K.; Uehara, A.; Hashikawa, K.; Mieno, M.; Matsumoto, M.; Handa, N.; Nakabayashi, S.; Imaizumi, M.; Kamada, T. )

    1989-12-15

    In ischemic cerebrovascular disease, it is not clear whether platelet function in vitro actually reflects the situation in vivo. Using indium-111 platelet scintigraphy as a method for detecting platelet activation in vivo, we tried to elucidate this problem. Twenty eight patients with chronic stage of ischemic cerebrovascular disease (CVD) and 17 control subjects were examined. Platelet scintigrams were positive in 9 of 28 patients in CVD, while all were negative in control. A comparison of the results obtained from qualitative platelet imaging and platelet aggregability was performed to evaluate whether threshold aggregation concentration (TAC) grade differed across the three groups (control, CVD patients without platelet deposition and CVD patients with platelet deposition). CVD patients with platelet deposition showed a higher TAC than those patients who did not show platelet deposition (P less than 0.05) or control subjects without platelet deposition (P less than 0.05). These results suggest that some patients in chronic stages of CVD may have active platelet deposition on carotid atheromatous lesions, and presence of platelet deposition in vivo could contribute to reduce platelet reactivity in peripheral blood.