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Sample records for platelet concentrates feasibility

  1. Ultraviolet irradiation of platelet concentrates: Feasibility in transfusion practice

    SciTech Connect

    Andreu, G.; Boccaccio, C.; Lecrubier, C.; Fretault, J.; Coursaget, J.; LeGuen, J.P.; Oleggini, M.; Fournel, J.J.; Samama, M. )

    1990-06-01

    Ultraviolet (UV)-B irradiation abolishes lymphocyte functions (the ability to respond and to stimulate) in mixed lymphocyte culture (MLC). This effect may have practical application in the prevention or reduction of transfusion-induced alloimmunization against HLA class I antigens. To study this, platelet concentrates (PCs) were obtained with a cell separator, suspended in autologous plasma in a final volume of 400 mL, and transferred into a large (22 X 30 cm) cell culture bag. This plastic showed a good transmittance of UV-B rays at 310 nm (54%). PCs were placed between two quartz plates (surface of irradiation = 25 X 37 cm), and the two sides were irradiated simultaneously. Energy delivered to the surface of the plastic bag was automatically monitored. The ability to respond (in MLC and to phytohemagglutinin) and to stimulate allogeneic lymphocytes was completely abolished with energy of 0.75 J per cm2 (irradiation time less than 3 min). The temperature increase during irradiation was negligible. Platelet aggregation (collagen, adrenalin, ADP, arachidonic acid, ristocetin) was not impaired if UV-B energy was below 3 J per cm2. Recovery and survival of autologous 111In-labeled platelets were studied in four volunteers; no differences were found between UV-B-treated (1.5 J/cm2) platelets and untreated platelets. These results show that a large-scale clinical trial using UV-B-irradiated PCs to prevent HLA alloimmunization is feasible.

  2. Quality assessment of platelet concentrates prepared by platelet rich plasma-platelet concentrate, buffy coat poor-platelet concentrate (BC-PC) and apheresis-PC methods

    PubMed Central

    Singh, Ravindra P.; Marwaha, Neelam; Malhotra, Pankaj; Dash, Sumitra

    2009-01-01

    Background: Platelet rich plasma-platelet concentrate (PRP-PC), buffy coat poor-platelet concentrate (BC-PC), and apheresis-PC were prepared and their quality parameters were assessed. Study Design: In this study, the following platelet products were prepared: from random donor platelets (i) platelet rich plasma - platelet concentrate (PRP-PC), and (ii) buffy coat poor-platelet concentrate (BC-PC) and (iii) single donor platelets (apheresis-PC) by different methods. Their quality was assessed using the following parameters: swirling, volume of the platelet concentrate, platelet count, WBC count and pH. Results: A total of 146 platelet concentrates (64 of PRP-PC, 62 of BC-PC and 20 of apheresis-PC) were enrolled in this study. The mean volume of PRP-PC, BC-PC and apheresis-PC was 62.30±22.68 ml, 68.81±22.95 ml and 214.05±9.91 ml and ranged from 22-135 ml, 32-133 ml and 200-251 ml respectively. The mean platelet count of PRP-PC, BC-PC and apheresis-PC was 7.6±2.97 × 1010/unit, 7.3±2.98 × 1010/unit and 4.13±1.32 × 1011/unit and ranged from 3.2 –16.2 × 1010/unit, 0.6-16.4 × 1010/unit and 1.22-8.9 × 1011/unit respectively. The mean WBC count in PRP-PC (n = 10), BC-PC (n = 10) and apheresis-PC (n = 6) units was 4.05±0.48 × 107/unit, 2.08±0.39 × 107/unit and 4.8±0.8 × 106/unit and ranged from 3.4 -4.77 × 107/unit, 1.6-2.7 × 107/unit and 3.2 – 5.2 × 106/unit respectively. A total of 26 units were analyzed for pH changes. Out of these units, 10 each were PRP-PC and BC-PC and 6 units were apheresis-PC. Their mean pH was 6.7±0.26 (mean±SD) and ranged from 6.5 – 7.0 and no difference was observed among all three types of platelet concentrate. Conclusion: PRP-PC and BC-PC units were comparable in terms of swirling, platelet count per unit and pH. As expected, we found WBC contamination to be less in BC-PC than PRP-PC units. Variation in volume was more in BC-PC than PRP-PC units and this suggests that further standardization is required for

  3. Platelet concentration in platelet concentrates and periodontal regeneration-unscrambling the ambiguity

    PubMed Central

    Suchetha, A.; Lakshmi, P.; Bhat, Divya; Mundinamane, Darshan B.; Soorya, K. V.; Bharwani, G. Ashit

    2015-01-01

    Context: Platelet-rich-plasma (PRP) and Platelet-rich-fibrin (PRF) are extensively used autologous platelet concentrates in periodontal regeneration, and PRF has a better efficacy as compared to PRP. The rationale for this difference has often been attributed to the difference in the structure of the fibrin matrix. However, the effect of concentration of platelets on the regenerative potential of these concentrates is obscure. Aims: The study was conducted to evaluate and compare, clinically and radiographically, the efficacy of PRF and PRP in the treatment of periodontal endosseous defects and to assess the effect of platelet concentration on periodontal regeneration. Materials and Methods: Twenty intrabony defects were selected and divided into two groups randomly by the coin toss method. Group I received PRP and Group II subjects were treated with PRF. The platelet counts in PRP and PRF were analyzed. Clinical and radiological parameters were assessed at baseline and 3, 6, and 9 months postoperatively. Statistical Analysis: Kruskal–Wallis Chi-square test, Wilcoxon signed rank test, t-test, and Spearman's rank correlation were used for statistical analysis of data. Results: There was statistically significant improvement in all the parameters in the two groups except in relation to gingival recession. There was a statistically significant difference between the platelet count in Group I and Group II (P = 0.002). Conclusion: PRP and PRF appear to have nearly comparable effects in terms of periodontal regeneration. The concentration of platelets appears to play a paradoxical role in regeneration. The regenerative potential of platelets appears to be optimal within a limited range. PMID:26681857

  4. Formed platelet combustor liner construction feasibility, phase A

    NASA Technical Reports Server (NTRS)

    Hayes, W. A.; Janke, D. E.

    1992-01-01

    Environments generated in high pressure liquid rocket engines impose severe requirements on regeneratively cooled combustor liners. Liners fabricated for use in high chamber pressures using conventional processes suffer from limitations that can impair operational cycle life and can adversely affect wall compatibility. Chamber liners fabricated using formed platelet technology provide an alternative to conventional regeneratively cooled liners (an alternative that has many attractive benefits). A formed platelet liner is made from a stacked assembly of platelets with channel features. The assembly is diffusion bonded into a flat panel and then three-dimensionally formed into a section of a chamber. Platelet technology permits the liner to have very precisely controlled and thin hot gas walls and therefore increased heat transfer efficiency. Further cooling efficiencies can be obtained through enhanced design flexibility. These advantages translate into increased cycle life and enhanced wall compatibility. The increased heat transfer efficiency can alternately be used to increase engine performance or turbopump life as a result of pressure drop reductions within the regeneratively cooled liner. Other benefits can be obtained by varying the materials of construction within the platelet liner to enhance material compatibility with operating environment or with adjoining components. Manufacturing cost savings are an additional benefit of a formed platelet liner. This is because of reduced touch labor and reduced schedule when compared to conventional methods of manufacture. The formed platelet technology is not only compatible with current state-of-the art combustion chamber structural support and manifolding schemes, it is also an enabling technology that allows the use of other high performance and potentially low cost methods of construction for the entire combustion chamber assembly. The contract under which this report is submitted contains three phases: (1) phase

  5. Optimized Preparation Method of Platelet-Concentrated Plasma and Noncoagulating Platelet-Derived Factor Concentrates: Maximization of Platelet Concentration and Removal of Fibrinogen

    PubMed Central

    Araki, Jun; Jona, Masahiro; Eto, Hitomi; Aoi, Noriyuki; Kato, Harunosuke; Suga, Hirotaka; Doi, Kentaro; Yatomi, Yutaka

    2012-01-01

    Abstract Platelet-rich plasma (PRP) has been clinically used as an easily prepared growth factor cocktail that can promote wound healing, angiogenesis, and tissue remodeling. However, the therapeutic effects of PRP are still controversial, due partly to the lack of optimized and standardized preparation protocols. We used whole blood (WB) samples to optimize the preparation protocols for PRP, white blood cell-containing (W-PRP), platelet-concentrated plasma (PCP), and noncoagulating platelet-derived factor concentrate (PFC). PRP and W-PRP were most efficiently collected by 10 min centrifugation in a 15-mL conical tube at 230–270 g and 70 g, respectively. To prepare PCP, platelets were precipitated by centrifugation of PRP at >2300 g, 90% of supernatant plasma was removed, and the platelets were resuspended. For preparation of noncoagulating PFC, the supernatant was replaced with one-tenth volume of saline, followed by platelet activation with thrombin. Platelet (before activation) and platelet-derived growth factor (PDGF)-BB (after activation) concentrations in PCP were approximately 20 times greater than those in WB, whereas PFC contained a 20-times greater concentration of platelets before platelet activation and a 50-times greater concentration of PDGF-BB without formation of a fibrin gel after platelet activation than WB. Surprisingly, total PDGF-BB content in the PFC was twice that of activated WB, which suggested that a substantial portion of the PDGF-BB became trapped in the fibrin glue, and replacement of plasma with saline is crucial for maximization of platelet-derived factors. As an anticoagulant, ethylene di-amine tetra-acetic acid disodium inhibited platelet aggregation more efficiently than acid citrate dextrose solution, resulting in higher nonaggregated platelet yield and final PDGF-BB content. These results increase our understanding of how to optimize and standardize preparation of platelet-derived factors at maximum concentrations. PMID

  6. 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

  7. Platelet concentrates: Balancing between efficacy and safety?

    PubMed

    Lozano, Miguel; Cid, Joan

    2016-01-01

    Platelet transfusions continue to be the mainstay to treat patients with quantitative and qualitative platelet disorders. Each year, about 10 millions of platelet transfusions are administered to patients worldwide with marked differences in usage between regions depending on socioeconomic development of the countries. Unfortunately, its use is associated to immune and non-immune side effects. Among the non-immune, bacterial contamination is still the major infectious risk. When bacterial culture methods are introduced for preventing bacterial septic reactions it has been found that this strategy reduce to one half the septic reactions, but do not eliminate completely that risk. To remove completely the risk, a new bacteria detection test at the time of issuance in the case of platelets stored for four or five days would be needed. Pathogen inactivation (PI) methods already in the market (based in the addition of amotosalen (A-L) or riboflavin (R-L) and the illumination with ultraviolet light) or under development (ultraviolet light C and agitation) have shown to be efficacious in the inactivation of bacteria and no cases of septic reactions associated to a pathogen-reduced product has been identified. However, it has been shown that PI technologies have measurable effects on platelet in vitro parameters and reduce the recovery and survival of treated platelets in vivo. Although these effects do not hamper the hemostatic capacity of treated platelets, an increased usage associated with PI technologies has been reported. This increase in utilization seems to be the toll to be paid if we want to completely eliminate the risk of bacterial sepsis in the recipients of platelet transfusion. PMID:27476010

  8. Platelet serotonin concentration and depressive symptoms in patients with schizophrenia.

    PubMed

    Peitl, Vjekoslav; Vidrih, Branka; Karlović, Zoran; Getaldić, Biserka; Peitl, Milena; Karlović, Dalibor

    2016-05-30

    Depressive symptoms seem to be frequent in schizophrenia, but so far they have received less attention than other symptom domains. Impaired serotonergic neurotransmission has been implicated in the pathogenesis of depression and schizophrenia. The objectives of this study were to investigate platelet serotonin concentrations in schizophrenic patients with and without depressive symptoms, and to investigate the association between platelet serotonin concentrations and symptoms of schizophrenia, mostly depressive symptoms. A total of 364 patients were included in the study, 237 of which had significant depressive symptoms. Significant depressive symptoms were defined by the cut-off score of 7 or more on Calgary Depression Rating Scale (CDSS). Platelet serotonin concentrations were assessed by the enzyme-linked immunosorbent assay (ELISA). Prevalence of depression in patients with schizophrenia was 65.1%. Schizophrenic patients with depressive symptoms showed lower platelet serotonin concentrations (mean±SD; 490.6±401.2) compared to schizophrenic patients without depressive symptoms (mean±SD; 660.9±471.5). An inverse correlation was established between platelet serotonin concentration and depressive symptoms, with more severe symptoms being associated with lower platelet serotonin concentrations. Depressive symptoms in schizophrenic patients may be associated with reduced concentrations of platelet serotonin. PMID:27137969

  9. 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.

  10. 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

  11. Effective ultraviolet irradiation of platelet concentrates in teflon bags

    SciTech Connect

    Capon, S.M.; Sacher, R.A.; Deeg, H.J. )

    1990-10-01

    Several plastic materials used in blood storage were evaluated for their ability to transmit ultraviolet B (UVB) light. A plastic bag manufactured from sheets of transparent Teflon efficiently (78-86%) transmitted UVB light and was employed in subsequent functional studies of lymphocytes and platelets exposed to UVB light while contained in these bags. In vitro experiments showed a UVB dose-dependent abrogation of lymphocyte responder and stimulator functions, with concurrent preservation of platelet aggregation responses. In a phase I pilot study, UVB-treated platelet concentrates were administered to four bone marrow transplant recipients. Adverse effects attributable to the transfusions were not observed, and patients showed clinically effective transfusion responses. No patient developed lymphocytotoxic HLA or platelet antibodies. These studies suggest that platelets can be effectively irradiated with UVB light in a closed system. However, numerous variables, including container material, volume and composition of contents, steady exposure versus agitation, and exact UV wavelength, must be considered.

  12. Regulating VEGF signaling in platelet concentrates via specific VEGF sequestering.

    PubMed

    Belair, David G; Le, Ngoc Nhi; Murphy, William L

    2016-05-26

    Platelets contain an abundance of growth factors that mimic the composition of the wound healing milieu, and platelet-derived VEGF in particular can negatively influence wound healing if unregulated. Here, we sought to capture and regulate the activity of VEGF factor from human platelets using poly(ethylene glycol) microspheres. In this communication, we demonstrate that platelet freeze/thaw produced significantly higher levels of Vascular Endothelial Growth Factor (VEGF) than either calcium chloride treatment, protease activated receptor 1 activating peptide (PAR1AP) treatment, or thrombin treatment. PEG microspheres containing a VEGF-binding peptide (VBP), derived from VEGFR2, sequestered VEGF from platelet concentrate, prepared via freeze/thaw, and reduced the bioactivity of platelet concentrate in HUVEC culture, which suggests that VBP microspheres sequestered and reduced the activity of VEGF from patient-derived platelets. Here, we demonstrate the ability of VEGF sequestering microspheres to regulate the activity of VEGF derived from a growth factor-rich autologous human blood product. PMID:27010034

  13. Concentration of platelets and growth factors in platelet-rich plasma from Goettingen minipigs.

    PubMed

    Jungbluth, Pascal; Grassmann, Jan-Peter; Thelen, Simon; Wild, Michael; Sager, Martin; Windolf, Joachim; Hakimi, Mohssen

    2014-01-01

    In minipigs little is known about the concentration of growth factors in plasma, despite their major role in several patho-physiological processes such as healing of fractures. This prompted us to study the concentration of platelets and selected growth factors in plasma and platelet-rich plasma (PRP) preparation of sixteen Goettingen minipigs. Platelet concentrations increased significantly in PRP in comparison to native blood plasma. Generally, significant increase in the concentration of all growth factors tested was observed in the PRP in comparison to the corresponding plasma or serum. Five of the plasma samples examined contained detectable levels of bone morphogenic protein 2 (BMP-2) whereas eleven of the plasma or serum samples contained minimal amounts of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF-bb) respectively. On the other hand variable concentrations of bone morphogenic protein 7 (BMP-7) and transforming growth factor β1 (TGF-β1) were measured in all plasma samples. In contrast, all PRP samples contained significantly increased amounts of growth factors. The level of BMP-2, BMP-7, TGF-β1, VEGF and PDGF-bb increased by 17.6, 1.5, 7.1, 7.2 and 103.3 fold, in comparison to the corresponding non-enriched preparations. Moreover significant positive correlations were found between platelet count and the concentrations of BMP-2 (r=0.62, p<0.001), TGF-β1 (r=0.85, p<0.001), VEGF (r=0.46, p<0.01) and PDGF-bb (r=0.9, p<0.001). Our results demonstrate that selected growth factors are present in the platelet-rich plasma of minipigs which might thus serve as a source of autologous growth factors. PMID:26504722

  14. The influence of environmental variables on platelet concentration in horse platelet-rich plasma.

    PubMed

    Rinnovati, Riccardo; Romagnoli, Noemi; Gentilini, Fabio; Lambertini, Carlotta; Spadari, Alessandro

    2016-01-01

    Platelet-rich plasma (PRP) commonly refers to blood products which contain a higher platelet (PLT) concentration as compared to normal plasma. Autologous PRP has been shown to be safe and effective in promoting the natural processes of soft tissue healing or reconstruction in humans and horses. Variability in PLT concentration has been observed in practice between PRP preparations from different patients or from the same individual under different conditions. A change in PLT concentration could modify PRP efficacy in routine applications. The aim of this study was to test the influence of environmental, individual and agonistic variables on the PLT concentration of PRP in horses. Six healthy Standardbred mares were exposed to six different variables with a one-week washout period between variables, and PRP was subsequently obtained from each horse. The variables were time of withdrawal during the day (morning/evening), hydration status (overhydration/dehydration) treatment with anti-inflammatory drugs and training periods on a treadmill. The platelet concentration was significantly higher in horses treated with a non-steroidal anti-inflammatory drug (P = 0.03). The leukocyte concentration increased 2-9 fold with respect to whole blood in the PRP which was obtained after exposure to all the variable considered. Environmental variation in platelet concentration should be taken into consideration during PRP preparation. PMID:27377748

  15. Platelet Concentration in Platelet-Rich Plasma Affects Tenocyte Behavior In Vitro

    PubMed Central

    Rughetti, Anna; Dal Mas, Antonella; Properzi, Gianfranco; Calvisi, Vittorio

    2014-01-01

    Since tendon injuries and tendinopathy are a growing problem, sometimes requiring surgery, new strategies that improve conservative therapies are needed. Platelet-rich plasma (PRP) seems to be a good candidate by virtue of its high content of growth factors, most of which are involved in tendon healing. This study aimed to evaluate if different concentrations of platelets in PRP have different effects on the biological features of normal human tenocytes that are usually required during tendon healing. The different platelet concentrations tested (up to 5 × 106 plt/µL) stimulated differently tenocytes behavior; intermediate concentrations (0.5 × 106, 1 × 106 plt/µL) strongly induced all tested processes (proliferation, migration, collagen, and MMPs production) if compared to untreated cells; on the contrary, the highest concentration had inhibitory effects on proliferation and strongly reduced migration abilities and overall collagen production but, at the same time, induced increasing MMP production, which could be counterproductive because excessive proteolysis could impair tendon mechanical stability. Thus, these in vitro data strongly suggest the need for a compromise between extremely high and low platelet concentrations to obtain an optimal global effect when inducing in vivo tendon healing. PMID:25147809

  16. Platelet concentration in platelet-rich plasma affects tenocyte behavior in vitro.

    PubMed

    Giusti, Ilaria; D'Ascenzo, Sandra; Mancò, Annalisa; Di Stefano, Gabriella; Di Francesco, Marianna; Rughetti, Anna; Dal Mas, Antonella; Properzi, Gianfranco; Calvisi, Vittorio; Dolo, Vincenza

    2014-01-01

    Since tendon injuries and tendinopathy are a growing problem, sometimes requiring surgery, new strategies that improve conservative therapies are needed. Platelet-rich plasma (PRP) seems to be a good candidate by virtue of its high content of growth factors, most of which are involved in tendon healing. This study aimed to evaluate if different concentrations of platelets in PRP have different effects on the biological features of normal human tenocytes that are usually required during tendon healing. The different platelet concentrations tested (up to 5 × 10(6) plt/µL) stimulated differently tenocytes behavior; intermediate concentrations (0.5 × 10(6), 1 × 10(6) plt/µL) strongly induced all tested processes (proliferation, migration, collagen, and MMPs production) if compared to untreated cells; on the contrary, the highest concentration had inhibitory effects on proliferation and strongly reduced migration abilities and overall collagen production but, at the same time, induced increasing MMP production, which could be counterproductive because excessive proteolysis could impair tendon mechanical stability. Thus, these in vitro data strongly suggest the need for a compromise between extremely high and low platelet concentrations to obtain an optimal global effect when inducing in vivo tendon healing. PMID:25147809

  17. 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 ...

  18. Rapid Screening Method for Detection of Bacteria in Platelet Concentrates

    PubMed Central

    Ribault, S.; Harper, K.; Grave, L.; Lafontaine, C.; Nannini, P.; Raimondo, A.; Faure, I. Besson

    2004-01-01

    Public awareness has long focused on the risks of the transmission of viral agents through blood product transfusion. This risk, however, pales in comparison to the less publicized danger associated with the transfusion of blood products contaminated with bacteria, in particular, platelet concentrates. Up to 1,000 cases of clinical sepsis after the transfusion of platelet concentrates are reported annually in the United States. The condition is characterized by acute reaction symptoms and the rapid onset of septicemia and carries a 20 to 40% mortality rate. The urgent need for a method for the routine screening of platelet concentrates to improve patient safety has long been recognized. We describe the development of a rapid and highly sensitive method for screening for bacteria in platelet concentrates for transfusion. No culture period is required; and the entire procedure, from the time of sampling to the time that the final result is obtained, takes less than 90 min. The method involves three basic stages: the selective removal of platelets by filtration following activation with a monoclonal antibody, DNA-specific fluorescent labeling of bacteria, and concentration of the bacteria on a membrane surface for enumeration by solid-phase cytometry. The method offers a universal means of detection of live, nondividing, or dead gram-negative and gram-positive bacteria in complex cellular blood products. The sensitivity is higher than those of the culture-based methods available at present, with a detection limit of 10 to 102 CFU/ml, depending upon the bacterial strain. PMID:15131147

  19. Rapid screening method for detection of bacteria in platelet concentrates.

    PubMed

    Ribault, S; Harper, K; Grave, L; Lafontaine, C; Nannini, P; Raimondo, A; Faure, I Besson

    2004-05-01

    Public awareness has long focused on the risks of the transmission of viral agents through blood product transfusion. This risk, however, pales in comparison to the less publicized danger associated with the transfusion of blood products contaminated with bacteria, in particular, platelet concentrates. Up to 1,000 cases of clinical sepsis after the transfusion of platelet concentrates are reported annually in the United States. The condition is characterized by acute reaction symptoms and the rapid onset of septicemia and carries a 20 to 40% mortality rate. The urgent need for a method for the routine screening of platelet concentrates to improve patient safety has long been recognized. We describe the development of a rapid and highly sensitive method for screening for bacteria in platelet concentrates for transfusion. No culture period is required; and the entire procedure, from the time of sampling to the time that the final result is obtained, takes less than 90 min. The method involves three basic stages: the selective removal of platelets by filtration following activation with a monoclonal antibody, DNA-specific fluorescent labeling of bacteria, and concentration of the bacteria on a membrane surface for enumeration by solid-phase cytometry. The method offers a universal means of detection of live, nondividing, or dead gram-negative and gram-positive bacteria in complex cellular blood products. The sensitivity is higher than those of the culture-based methods available at present, with a detection limit of 10 to 10(2) CFU/ml, depending upon the bacterial strain. PMID:15131147

  20. [Isosorbide dinitrate inhibits in vitro platelet aggregation at submicromolar concentrations].

    PubMed

    Gachet, C; Guillou, J; Moog, S; Cazenave, J P

    1992-04-01

    Nitrate derivatives have in vivo and in vitro platelet anti-aggregant properties in addition to their vasodilatory effects. The mode of action is related to increased intracytoplasmic cyclic GMP concentrations. It has been shown that isosorbide dinitrate (ISDN) has this type of platelet anti-aggregant activity but the reported results about the active concentrations and the inhibited pathways of activation are contradictory. This study was designed to determine whether ISDN has in vitro platelet anti-aggregant activity at low doses and to verify if this effect is selective by aggregation induced by ADP. Finally, a possible potentialisation of the inhibitors due to ISDN was looked for with cyclic nucleotide phosphodiesterase inhibitors and with agents simulating the effect of adenylate cyclase. The results showed that: 1) ISDN had platelet anti-aggregant activity in vitro at concentrations of about 10-7 M, 2) that this effect was not limited to the aggregation induced by ADP as the aggregation induced by PAF-acether was also inhibited by low dose ISDN, 3) of the cyclic nucleotide modulators tested, only quercetine (flavonoide) potentialised the effects of ISDN. PMID:1326933

  1. Platelet and growth factor concentrations in activated platelet-rich plasma: a comparison of seven commercial separation systems.

    PubMed

    Kushida, Satoshi; Kakudo, Natsuko; Morimoto, Naoki; Hara, Tomoya; Ogawa, Takeshi; Mitsui, Toshihito; Kusumoto, Kenji

    2014-06-01

    Platelet-rich plasma (PRP) is blood plasma that has been enriched with platelets. It holds promise for clinical use in areas such as wound healing and regenerative medicine, including bone regeneration. This study characterized the composition of PRP produced by seven commercially available separation systems (JP200, GLO PRP, Magellan Autologous Platelet Separator System, KYOCERA Medical PRP Kit, SELPHYL, MyCells, and Dr. Shin's System THROMBO KIT) to evaluate the platelet, white blood cell, red blood cell, and growth factor concentrations, as well as platelet-derived growth factor-AB (PDGF-AB), transforming growth factor beta-1 (TGF-β1), and vascular endothelial growth factor (VEGF) concentrations. PRP prepared using the Magellan Autologous Platelet Separator System and the KYOCERA Medical PRP Kit contained the highest platelet concentrations. The mean PDGF-AB concentration of activated PRP was the highest from JP200, followed by the KYOCERA Medical PRP Kit, Magellan Autologous Platelet Separator System, MyCells, and GLO PRP. TGF-β1 and VEGF concentrations varied greatly among individual samples, and there was almost no significant difference among the different systems, unlike for PDGF. The SELPHYL system produced PRP with low concentrations of both platelets and growth factors. Commercial PRP separation systems vary widely, and familiarity with their individual advantages is important to extend their clinical application to a wide variety of conditions. PMID:24748436

  2. Treatment of Platelet Concentrates with the Mirasol Pathogen Inactivation System Modulates Platelet Oxidative Stress and NF-κB Activation

    PubMed Central

    Johnson, Lacey; Marks, Denese

    2015-01-01

    Background Pathogen inactivation (PI) technologies for platelets aim to improve transfusion safety by preventing the replication of contaminating pathogens. However, as a consequence of treatment, aspects of the platelet storage lesion are amplified. Mirasol treatment also affects platelet signal transduction and apoptotic protein expression. The aim of this study was to examine the effect of Mirasol treatment on the generation of reactive oxygen species (ROS) and subsequent oxidative stress. Methods Pooled platelet concentrates were prepared in platelet-additive solution (70% SSP+ / 30% plasma). ABO-matched platelets were pooled and split, and treated with the Mirasol system (TerumoBCT) or left untreated as a control. Platelet samples were tested on day 1, 5, and 7 post-collection. Results Mirasol-treated platelets had increased formation of ROS by day 5 of storage. Oxidative damage, in the form of protein carbonylation, was higher in Mirasol-treated platelets, whilst no effect on nitrotyrosine formation or lipid peroxidation was detected. The NF-κB signaling pathway was also activated in Mirasol-treated platelets, with increased expression and phosphorylation of NF-κB p65 and IκBα. Conclusion These data demonstrate that Mirasol-treated platelets produce more ROS and display protein alterations consistent with oxidative damage. PMID:26195930

  3. Applications of ultraviolet light in the preparation of platelet concentrates

    SciTech Connect

    Pamphilon, D.H.; Corbin, S.A.; Saunders, J.; Tandy, N.P.

    1989-06-01

    Passenger lymphocytes in platelet concentrates (PCs) may induce the formation of lymphocytotoxic antibodies (LCTAbs) and subsequent refractoriness to platelet transfusions. Ultraviolet (UV) irradiation can prevent lymphocytes' acting as stimulator or responder cells in mixed-lymphocyte reactions (MLRs) and could theoretically prevent LCTAb formation in vivo. A system has been devised for the delivery of UV irradiation to PCs; platelet storage characteristics and MLRs were evaluated in UV-irradiated PCs harvested from healthy donors with the Haemonetics V50 and PCS cell separators. MLR and response to phytohemagglutinin stimulation were abolished by a dose of 3000 joules per m2 at a mean wavelength of 310 nm. Platelet aggregatory responses to adenosine diphosphate (ADP), ristocetin, collagen and epinephrine, hypotonic shock response, and pH showed no important differences when control PCs and PCs irradiated as above were compared during 5 days of storage in Fenwal PL-1240 packs. Lactate production during storage was significantly higher in UV-treated PCs (p less than 0.001), but values did not exceed 20 mmol per L. UV transmission at 310 nm in standard blood product containers, including the Fenwal PL-146, PL-1240, and PL-732, was low (less than 30%), but it was acceptable in the Delmed Cryostorage and DuPont SteriCell packs (greater than 50%). UV irradiation may provide a simple and inexpensive means of producing nonimmunogenic PCs.

  4. 21 CFR 864.9575 - Environmental chamber for storage of platelet concentrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Environmental chamber for storage of platelet... Establishments That Manufacture Blood and Blood Products § 864.9575 Environmental chamber for storage of platelet concentrate. (a) Identification. An environmental chamber for storage of platelet concentrate is a device...

  5. 21 CFR 864.9575 - Environmental chamber for storage of platelet concentrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Environmental chamber for storage of platelet... Establishments That Manufacture Blood and Blood Products § 864.9575 Environmental chamber for storage of platelet concentrate. (a) Identification. An environmental chamber for storage of platelet concentrate is a device...

  6. 21 CFR 864.9575 - Environmental chamber for storage of platelet concentrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Environmental chamber for storage of platelet... Establishments That Manufacture Blood and Blood Products § 864.9575 Environmental chamber for storage of platelet concentrate. (a) Identification. An environmental chamber for storage of platelet concentrate is a device...

  7. Metabolic status of platelet concentrates during extended storage: improvement with pharmacological inhibitors and reduced surface-to-volume ratio.

    PubMed

    Bode, A P; Miller, D T

    1989-01-01

    The depletion of plasma nutrients and buffering capacity may present a potential barrier to the long-term liquid storage of platelet concentrates (PC). We have found that PC prepared with reversible inhibitors of platelet activation added to the citrate anticoagulant and stored at a reduced surface-to-volume (S/V) ratio have a much slower rate of lactate build-up (p less than 0.01), slower consumption of glucose (p = 0.05), and more stable pH (p less than 0.01) than controls. By pO2 and pCO2 measurements, PC prepared with inhibitors showed evidence of continued respiration and responsiveness even after storage at 22 degrees C for 15 days. In addition, these PC released only 11% of the total cellular LDH during the storage period as compared to the release of 43-67% of the total LDH in control PC. Maximum benefit of the inhibitors was seen after reduction of the S/V ratio of the storage container, which was made possible by the reduced metabolic demands of platelets stored in the unactivated state. These data suggest that the fall in pH and loss of platelet integrity associated with the platelet storage lesion are correlated with a high metabolic rate which can be controlled by inhibiting the activation of platelets during preparation and storage. The use of these inhibitors and reduced bag surface area may make prolonged liquid storage of platelets feasible. PMID:2477949

  8. Photochemical inactivation of pathogenic bacteria in human platelet concentrates.

    PubMed

    Lin, L; Londe, H; Janda, J M; Hanson, C V; Corash, L

    1994-05-01

    Platelet concentrates (PC) may be infrequently contaminated with low levels of bacteria that can cause septicemia and death in patients receiving transfusion therapy. We evaluated the efficacy of a photochemical decontamination (PCD) technique using 8-methoxypsoralen (8-MOP) and long wavelength UV light (UVA) to inactivate bacteria in standard therapeutic PC. Twelve phylogenetically distinct pathogenic bacteria, 5 gram-positive and 7 gram-negative organisms, were seeded into PC to a final challenge dose ranging from 10(5) to 10(7) colony-forming units (CFU)/mL. Contaminated PC were treated with 8-MOP (5 micrograms/mL) and 5 J/cm2 of UVA, a PCD treatment regimen found to adequately preserve in vitro platelet function. Greater than 10(5) CFU/mL of all 5 gram-positive (Staphylococcus aureus, Streptococcus epidermidis, Streptococcus pyogenes, Listeria monocytogenes, and Corynebacterium minutissimum) and 2 of the gram-negative (Escherichia coli and Yersinia enterocolitica) organisms were inactivated. The remaining 5 gram-negative organisms were more resistant, with less than 10(1) to 10(3.7) CFU/mL inactivated under these conditions. The inactivation efficiency for this resistant group of gram-negative organisms was improved when PC were resuspended in a synthetic storage medium with reduced plasma protein concentration (15%) and an increased 8-MOP concentration (23.4 micrograms/mL). Illumination with 3 J/cm2 of UVA in this system inactivated greater than 10(5) CFU/mL of 4 resistant gram-negative organisms (Salmonella choleraesuis, Enterobacter cloacae, Serratia marcescens, and Klebsiella pneumoniae) and 10(4.1) CFU/mL of the most resistant gram-negative organism (Pseudomonas aeruginosa). This level of PCD treatment did not adversely affect in vitro platelet function. These results demonstrate that PCD using 8-MOP (5 to 23.4 micrograms/mL) effectively inactivated high levels of pathogenic bacteria in PC with adequate preservation of in vitro platelet properties. PMID

  9. 21 CFR 864.9575 - Environmental chamber for storage of platelet concentrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Environmental chamber for storage of platelet concentrate. 864.9575 Section 864.9575 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... concentrate. (a) Identification. An environmental chamber for storage of platelet concentrate is a device...

  10. Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates

    SciTech Connect

    Lin, L.; Wiesehahn, G.P.; Morel, P.A.; Corash, L. )

    1989-07-01

    Transmission of viral diseases through blood products remains an unsolved problem in transfusion medicine. We have developed a psoralen photochemical system for decontamination of platelet concentrates in which platelets are treated with long wavelength ultraviolet radiation (UVA, 320-400 nm) in the presence of 8-methoxypsoralen (8-MOP). Bacteria, RNA viruses, and DNA viruses ranging in genome size from 1.2 x 10(6) daltons, encompassing the size range of human pathogens, were inoculated into platelet concentrates and subjected to treatment. This system inactivated 25 to 30 logs/h of bacteria Escherichia coli or Staphylococcus aureus, 6 logs/h of bacteriophage fd, 0.9 log/h of bacteriophage R17 and 1.1 logs/h of feline leukemia virus (FeLV) in platelet concentrates maintained in standard storage bags. Platelet integrity and in vitro function before, immediately following photochemical treatment, and during prolonged storage after treatment, were evaluated by measuring: (1) extracellular pH; (2) platelet yields; (3) extracellular lactate dehydrogenase (LDH) levels; (4) platelet morphology; (5) platelet aggregation responsiveness; (6) thromboxane beta-2 (TXB-2) production; (7) dense body secretion; and (8) alpha granule secretion. These assays demonstrated that this photochemical inactivation system inactivated bacteria and viruses in platelet concentrates with minimal adverse effects on the in vitro function of platelets in comparison to untreated control concentrates maintained under current, standard blood bank conditions.

  11. Expired and Pathogen-Inactivated Platelet Concentrates Support Differentiation and Immunomodulation of Mesenchymal Stromal Cells in Culture.

    PubMed

    Jonsdottir-Buch, Sandra Mjoll; Sigurgrimsdottir, Hildur; Lieder, Ramona; Sigurjonsson, Olafur Eysteinn

    2015-01-01

    Platelet lysates have been reported as suitable cell culture supplement for cultures of mesenchymal stromal cells (MSCs). The demand for safe and animal-free cultures of MSCs is linked to the potential application of MSCs in clinics. While the use of platelet lysates offers an alternative to animal serum in MSC cultures, obtaining supplies of fresh platelet concentrates for lysate production is challenging and raises concerns due to the already existing shortage of platelet donors. We have previously demonstrated that expired platelet concentrates may represent a good source of platelets for lysate production without competing with blood banks for platelet donors. The INTERCEPT Blood System™ treatment of platelet concentrates allows for prolonged storage up to 7 days, using highly specific technology based on amotosalen and UV-A light. The INTERCEPT system has therefore been implemented in blood processing facilities worldwide. In this study, we evaluated the suitability of INTERCEPT-treated, expired platelet concentrates, processed into platelet lysates, for the culture of MSCs compared to nontreated expired platelets. Bone marrow-derived MSCs were cultured in media supplemented with either platelet lysates from traditionally prepared expired platelet concentrates or in platelet lysates from expired and pathogen-inactivated platelet concentrates. The effects of pathogen inactivation on the ability of the platelets to support MSCs in culture were determined by evaluating MSC immunomodulation, immunophenotype, proliferation, and trilineage differentiation. Platelet lysates prepared from expired and pathogen-inactivated platelet concentrates supported MSC differentiation and immunosuppression better compared to traditionally prepared platelet lysates from expired platelet units. Pathogen inactivation of platelets with the INTERCEPT system prior to use in MSC culture had no negative effects on MSC immunophenotype or proliferation. In conclusion, the use of expired

  12. Evaluation of autologous platelet concentrate for intertransverse process lumbar fusion.

    PubMed

    Sethi, Paul M; Miranda, Jose J; Kadiyala, Sudha; Patel, Tushar Ch; Panjabi, Manohar; Troiano, Nancy; Friedlaender, Gary E

    2008-04-01

    Data on the role of platelet concentrate (PC) in spinal fusion are limited. Using the New Zealand white rabbit model, we compared fusion rates at L5-L6 using 2 different volumes (1.5 cm(3), 3.0 cm(3)) of iliac crest autograft with and without PC (4 groups total, 10 animals in each). PC was collected from donor rabbits and adjusted to a concentration of 1 x 10(6) platelets/mL. Bone growth and fusion were evaluated using biomechanical, radiographic, and histologic testing. At 1.5 cm(3), autograft alone had a 29% fusion rate, compared with autograft plus PC, which had a 57% fusion rate (P = .06). At 3.0 cm(3), the fusion rate approached 90% in both groups. Radiologic fusion had a 70% correlation with biomechanical test results. Huo/Friedlaender scores were 4.3 (SD, 2.9) for 1.5-cm(3) autograft alone; 5.0 (SD, 3.5) for 1.5-cm(3) autograft plus PC; 4.7 (SD, 2.5) for 3.0-cm(3) autograft alone; and 7.7 (SD, 0.6) for 3.0-cm(3) autograft plus PC. For 1.5-cm(3) autograft, a trend toward improvement in biomechanically defined fusion was found when PC was added, which suggests that, when the amount of bone graft is limited, PC may function as a graft extender in posterolateral fusion. At higher volumes of bone graft, no appreciable difference was noted between groups. Although radiography revealed fusion masses, the technique was not useful in identifying pseudarthrosis. On histologic analysis, adding PC seemed to result in more mature bone at both volumes, with the most mature bone in the group with 3.0-cm(3) autograft plus PC. PMID:18535686

  13. The effect of obstruction of bag surface on platelet concentrate pH.

    PubMed

    Simon, T L

    1983-01-01

    Platelet concentrates stored in bags (made of a plastic film incorporating a new plasticizer) on flat-bed agitators for up to 5 days were found to have accelerated pH decline when the surface of the bag was obstructed with added labels and an invoice on the non-labeled side. Without the over-labeling and invoice, only one of 20 concentrates had a pH below 6.0, even at very high concentrations of platelets. Blood banks experiencing problems with pH decline in the platelet concentrates being stored up to 5 days should consider eliminating surface obstruction on the bag. PMID:6679386

  14. Effect of hyperbaric oxygen therapy combined with autologous platelet concentrate applied in rabbit fibula fraction healing

    PubMed Central

    Neves, Paulo César Fagundes; de Campos Vieira Abib, Simone; Neves, Rogério Fagundes; Pircchio, Oronzo; Saad, Karen Ruggeri; Saad, Paulo Fernandes; Simões, Ricardo Santos; Moreira, Marcia Bento; de Souza Laurino, Cristiano Frota

    2013-01-01

    OBJECTIVES: The purpose is to study the effects of hyperbaric oxygen therapy and autologous platelet concentrates in healing the fibula bone of rabbits after induced fractures. METHODS: A total of 128 male New Zealand albino rabbits, between 6–8 months old, were subjected to a total osteotomy of the proximal portion of the right fibula. After surgery, the animals were divided into four groups (n = 32 each): control group, in which animals were subjected to osteotomy; autologous platelet concentrate group, in which animals were subjected to osteotomy and autologous platelet concentrate applied at the fracture site; hyperbaric oxygen group, in which animals were subjected to osteotomy and 9 consecutive daily hyperbaric oxygen therapy sessions; and autologous platelet concentrate and hyperbaric oxygen group, in which animals were subjected to osteotomy, autologous platelet concentrate applied at the fracture site, and 9 consecutive daily hyperbaric oxygen therapy sessions. Each group was divided into 4 subgroups according to a pre-determined euthanasia time points: 2, 4, 6, and 8 weeks postoperative. After euthanasia at a specific time point, the fibula containing the osseous callus was prepared histologically and stained with hematoxylin and eosin or picrosirius red. RESULTS: Autologous platelet concentrates and hyperbaric oxygen therapy, applied together or separately, increased the rate of bone healing compared with the control group. CONCLUSION: Hyperbaric oxygen therapy and autologous platelet concentrate combined increased the rate of bone healing in this experimental model. PMID:24141841

  15. Platelets expressing P-selectin and platelet-derived microparticles in stored platelet concentrates bind to PSGL-1 on filtrated leukocytes.

    PubMed

    Nomura, S; Okamae, F; Abe, M; Hosokawa, M; Yamaoka, M; Ohtani, T; Onishi, S; Matsuzaki, T; Teraoka, A; Ishida, T; Fukuhara, S

    2000-10-01

    The levels of interleukin-6 and platelet-derived microparticles (PMPs) were measured in the blood of 137 patients with side effects from platelet concentrate (PC) transfusion with leukocyte removal filtration, P-selectin-expressing platelet and PMPs in stored PC before and after the filtration, and filtered leukocytes positive for P-selectin glycoprotein ligand-1. The side effects, which were observed in 203 transfusions for 84 patients with hematologic disease and 53 patients with nonhematologic disease with no significant difference between the two groups, included urticaria (75.9%), erythema (18.7%), and fever (17.2%), but no anaphylactic reactions. The levels of interleukin-6 and PMP correlated in both groups, and were significantly higher in the hematologic disease group than in the nonhematologic disease group. The level of PMP, but not interleukin-6, was significantly higher for patients testing positive for allergic reaction than for those testing negative. In the stored PC prior to filtration, the level of interleukin-6 was normal. The level of P-selectin-expressing platelets and PMPs was elevated before filtration, but was significantly lower after filtration. Taken together, the results suggest that PMP is involved in the generation of transfusion reactions, and indicate that both platelets and PMP displaying P-selectin bind to P-selectin glycoprotein ligand-1 of leukocytes retained by the leukocyte filter. PMID:11030527

  16. Thromboelastometric Monitoring of the Hemostatic Effect of Platelet Concentrates Transfusion in Thrombocytopenic Children Undergoing Chemotherapy

    PubMed Central

    Solomon, Cristina; Cadamuro, Janne; Jones, Neil

    2015-01-01

    Prophylactic platelet concentrates transfusion represents a therapeutic choice in patients with chemotherapy-induced thrombocytopenia. This prospective, non-interventional study evaluated the effects of platelet concentrates transfusion on thromboelastometric parameters of platelet function in 36 transfusion occasions for 11 thrombocytopenic children undergoing chemotherapy. Pre- and posttransfusion (1-2 hours) blood samples were analyzed using standard coagulation tests and thromboelastometry (ROTEM) measurements (EXTEM and FIBTEM tests). Platelet component of the clot was calculated based on the EXTEM and FIBTEM maximum clot elasticity (MCE) results. After transfusion, mean platelet count increased from 16.5 × 109/L to 43.0 × 109/L (P < .001) and platelet component increased from 34.1 to 73.0 (P < .001). Statistically significant increases for posttransfusion EXTEM parameters A10, A20, and maximum clot firmness (MCF) were observed compared to pretransfusion values (P < .001). The EXTEM α-angle values increased posttransfusion (P < .05). The FIBTEM measurements were comparable pre- and posttransfusion. The study showed that platelet concentrates transfusion in thrombocytopenic children undergoing chemotherapy improves platelet-related coagulation pattern. PMID:25525046

  17. UVC Irradiation for Pathogen Reduction of Platelet Concentrates and Plasma.

    PubMed

    Seltsam, Axel; Müller, Thomas H

    2011-01-01

    Besides the current efforts devoted to microbial risk reduction, pathogen inactivation technologies promise reduction of the residual risk of known and emerging infectious agents. A novel pathogen reduction process for platelets, the THERAFLEX UV-Platelets system, has been developed and is under clinical evaluation for its efficacy and safety. In addition, proof of principle has been shown for UVC treatment of plasma units. The pathogen reduction process is based on application of UVC light of a specific wavelength (254 nm) combined with intense agitation of the blood units to ensure a uniform treatment of all blood compartments. Due to the different absorption characteristics of nucleic acids and proteins, UVC irradiation mainly affects the nucleic acid of pathogens and leukocytes while proteins are largely preserved. UVC treatment significantly reduces the infectivity of platelet units contaminated by disease-causing viruses and bacteria. In addition, it inactivates residual white blood cells in the blood components while preserving platelet function and coagulation factors. Since no photoactive compound needs to be added to the blood units, photoreagent-related adverse events are excluded. Because of its simple and rapid procedure without the need to change the established blood component preparation procedures, UVC-based pathogen inactivation could easily be implemented in existing blood banking procedures. PMID:21779205

  18. Description of a double centrifugation tube method for concentrating canine platelets

    PubMed Central

    2013-01-01

    Background To evaluate the efficiency of platelet-rich plasma preparations by means of a double centrifugation tube method to obtain platelet-rich canine plasma at a concentration at least 4 times higher than the baseline value and a concentration of white blood cells not exceeding twice the reference range. A complete blood count was carried out for each sample and each concentrate. Whole blood samples were collected from 12 clinically healthy dogs (consenting blood donors). Blood was processed by a double centrifugation tube method to obtain platelet concentrates, which were then analyzed by a flow cytometry haematology system for haemogram. Platelet concentration and white blood cell count were determined in all samples. Results Platelet concentration at least 4 times higher than the baseline value and a white blood cell count not exceeding twice the reference range were obtained respectively in 10 cases out of 12 (83.3%) and 11 cases out of 12 (91.6%). Conclusions This double centrifugation tube method is a relatively simple and inexpensive method for obtaining platelet-rich canine plasma, potentially available for therapeutic use to improve the healing process. PMID:23876182

  19. Effects of anticoagulant on pH, ionized calcium concentration, and agonist-induced platelet aggregation in canine platelet-rich plasma.

    PubMed

    Callan, Mary Beth; Shofer, Frances S; Catalfamo, James L

    2009-04-01

    OBJECTIVE-To compare effects of 3.8% sodium citrate and anticoagulant citrate dextrose solution National Institutes of Health formula A (ACD-A) on pH, extracellular ionized calcium (iCa) concentration, and platelet aggregation in canine platelet-rich plasma (PRP). SAMPLE POPULATION-Samples from 12 dogs. PROCEDURES-Blood samples were collected into 3.8% sodium citrate (dilution, 1:9) and ACD-A (dilution, 1:5). Platelet function, pH, and iCa concentration were evaluated in PRP. Platelet agonists were ADP, gamma-thrombin, and convulxin; final concentrations of each were 20microm, 100nM, and 20nM, respectively. Washed platelets were used to evaluate effects of varying the pH and iCa concentration. RESULTS-Mean pH and iCa concentration were significantly greater in 3.8% sodium citrate PRP than ACD-A PRP. Platelet aggregation induced by ADP and gamma-thrombin was markedly diminished in ACD-A PRP, compared with results for 3.8% sodium citrate PRP. Anticoagulant had no effect on amplitude of convulxin-induced platelet aggregation. In washed platelet suspensions (pH, 7.4), there were no differences in amplitude of platelet aggregation induced by convulxin or gamma-thrombin at various iCa concentrations. Varying the pH had no effect on amplitude of aggregation induced by convulxin or gamma-thrombin, but the aggregation rate increased with increasing pH for both agonists. CONCLUSIONS AND CLINICAL RELEVANCE-Aggregation of canine platelets induced by ADP and gamma-thrombin was negligible in ACD-A PRP, which suggested an increase in extraplatelet hydrogen ion concentration inhibits signaling triggered by these agonists but not by convulxin. Choice of anticoagulant may influence results of in vitro evaluation of platelet function, which can lead to erroneous conclusions. PMID:19335102

  20. Evaluation of in vitro storage characteristics of cold stored platelet concentrates with N acetylcysteine (NAC).

    PubMed

    Handigund, Mallikarjun; Bae, Tae Won; Lee, Jaehyeon; Cho, Yong Gon

    2016-02-01

    Platelets play a vital role in hemostasis and thrombosis, and their demand and usage has multiplied many folds over the years. However, due to the short life span and storage constraints on platelets, it is allowed to store them for up to 7 days at room temperature (RT); thus, there is a need for an alternative storage strategy for extension of shelf life. Current investigation involves the addition of 50 mM N acetylcysteine (NAC) in refrigerated concentrates. Investigation results revealed that addition of NAC to refrigerated concentrates prevented platelet activation and reduced the sialidase activity upon rewarming as well as on prolonged storage. Refrigerated concentrates with 50 mM NAC expressed a 23.91 ± 6.23% of CD62P (P-Selectin) and 22.33 ± 3.42% of phosphotidylserine (PS), whereas RT-stored platelets showed a 46.87 ± 5.23% of CD62P and 25.9 ± 6.48% of phosphotidylserine (PS) after 5 days of storage. Further, key metabolic parameters such as glucose and lactate accumulation indicated reduced metabolic activity. Taken together, investigation and observations indicate that addition of NAC potentially protects refrigerated concentrates by preventing platelet activation, stabilizing sialidase activity, and further reducing the metabolic activity. Hence, we believe that NAC can be a good candidate for an additive solution to retain platelet characteristics during cold storage and may pave the way for extension of storage shelf life. PMID:26847865

  1. Increased Platelet Concentration does not Improve Functional Graft Healing in Bio-Enhanced ACL Reconstruction

    PubMed Central

    Fleming, Braden C.; Proffen, Benedikt L.; Vavken, Patrick; Shalvoy, Matthew R.; Machan, Jason T.; Murray, Martha M.

    2014-01-01

    Purpose The use of an extra-cellular matrix scaffold (ECM) combined with platelets to enhance healing of an ACL graft (“bio-enhanced ACL reconstruction”) has shown promise in animal models. However, the effects of platelet concentration on graft healing remains unknown. The objectives of this study were to determine if increasing the platelet concentration in the ECM scaffold would; 1) improve the graft biomechanical properties, and 2) decrease cartilage damage after surgery. Methods Fifty-five adolescent minipigs were randomized to 5 treatment groups; untreated ACL transection (n=10), conventional ACL reconstruction (n=15), and bio-enhanced ACL reconstruction using 1X (n=10), 3X (n=10) or 5X (n=10) platelet-rich plasma. The graft biomechanical properties, anteroposterior (AP) knee laxity, graft histology and macroscopic cartilage integrity were measured at 15 weeks. Results The mean linear stiffness of the bio-enhanced ACL reconstruction procedure using the 1X preparation was significantly greater than traditional reconstruction while the 3X and 5X preparations were not. The failure loads of all the ACL reconstructed groups were equivalent but significantly greater than untreated ACL transection. There were no significant differences in the ligament maturity index or AP laxity between reconstructed knees. Macroscopic cartilage damage was relatively minor, though significantly less when the ECM-platelet composite was used. Conclusions Only the 1X platelet concentration improved healing over traditional ACL reconstruction. Increasing the platelet concentration from 1X to 5X in the ECM scaffold did not further improve the graft mechanical properties. The use of an ECM-platelet composite decreased the amount of cartilage damage seen after ACL surgery. PMID:24633008

  2. Adsorption of anaphylatoxins and platelet-specific proteins by filtration of platelet concentrates with a polyester leukocyte reduction filter.

    PubMed

    Shimizu, T; Uchigiri, C; Mizuno, S; Kamiya, T; Kokubo, Y

    1994-01-01

    Anaphylatoxins generated during storage of platelet concentrates (PCs) may potentially have side effects on platelet transfusion. We evaluated the anaphylatoxin-scavenging abilities of white blood cell reduction filters. Among the commercially available filters for PCs, one made with polyester fiber (PL50) dramatically adsorbed C3a and C4a anaphylatoxins to the respective mean level of 1,721-208 ng/ml and 1,240-141 ng/ml in 3-day-old PCs. C3a and C4a were measured as the native and des Arg form of each complement by radioimmunoassay. C3a and C4a anaphylatoxins in the supernatant plasma fraction from 3-day-old PC again decreased from 1,136 to 114 ng/ml and from 1,086 to 65 ng/ml, respectively. The filter also adsorbed 85% of platelet factor 4 (PF4) and 31% of beta-thromboglobulin (beta-TG), which had been released from platelets into the plasma during storage. The plasma levels of adhesive proteins such as fibronectin, fibrinogen, and von Willebrand factor, and plasma lactate dehydrogenase activity did not decrease after filtration. Another polyester filter (PL5A), on the other hand, significantly increased C3a and C4a levels with filtration. In addition, there was no PF4 adsorption ability during the filtration. The filters for red cells (RC50, BPF4, and R500A) had no anaphylatoxin adsorption capabilities. The observed specific adsorption of anaphylatoxins might be attributed to the electrostatic force between the positively charged anaphylatoxins with high pI and the possibly negatively charged filter membranes. Since PF4 and beta-TG have positively charged moieties in the C-terminal position, the same adsorption mechanism might operate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8036783

  3. Plasma-depleted platelet concentrates prepared with a new washing solution.

    PubMed

    Shimizu, T; Shibata, K; Kora, S

    1993-01-01

    In certain clinical situations, complete removal of the plasma proteins from the platelet concentrates (PCs) is necessary by washing prior to transfusion. A simple electrolyte solution with a pH of 6.5 was developed for washing PCs. The platelet-rich plasma collected with acid-citrate-dextrose solution by apheresis in a 0.6-liter polyolefin bag was centrifuged. After removal of the supernatant plasma from pelleted platelet buttons, 200 ml of a washing solution consisting of 90 mM NaCl, 5 mM KCl, 3 mM MgCl2, 17 mM NaH2PO4, 8 mM Na2HPO4, 23 mM Na acetate, 17 mM Na3 citrate, 23.5 mM glucose, 2 mM adenine, 0.1% dextran, and 28.8 mM maltose (pH 6.5) was added to the pelleted platelet button. Steam sterilization of the solution was carried out under nitrogen to avoid caramelization of glucose. After resuspension of the pelleted platelet button with a washing solution and a second centrifugation, Seto additive solution (Seto sol, pH 7.4) was introduced into the bag to resuspend the platelet buttons for storage for 3 days at 22 degrees C. All of these procedures were completed within 3 h using a sterile docking device. In washed PCs, 99.1% of the plasma was removed and platelet recovery was 96%. The washed PCs were compared for 3 days with plasma-poor PCs consisting of 11% plasma and 89% Seto solution. There were no significant differences in percent hypotonic shock response, aggregation, energy metabolism, and morphology of platelets between the two groups during 3 days, except for significant swelling of 3-day-old platelets in washed PCs.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8447117

  4. Plasma free fatty acid metabolism during storage of platelet concentrates for transfusion.

    PubMed

    Cesar, J; DiMinno, G; Alam, I; Silver, M; Murphy, S

    1987-01-01

    New containers allow storage of platelet concentrates (PC) at 22 degrees C for up to 7 days, during which glycolytic and oxidative metabolism is vigorous. Recent evidence suggests that 85 percent of adenosine triphosphate regeneration is based on oxidative metabolism and that substrates other than glucose may be used. Because platelets can oxidize free fatty acids (FFA) as a possible source of energy during storage, the authors studied their availability, distribution, and turnover. Plasma FFA concentration was unchanged after 1 day of PC storage but significantly increased on Days 3, 5, and 7. Platelet-free plasma (PFP) stored under the same conditions as PC demonstrated a progressive increase in FFA, suggesting that some of the FFA accumulating in PC were derived from plasma rather than platelets. Indeed, during PC storage, plasma triglycerides decreased significantly, suggesting that they are a possible source of the increased levels of FFA found on Day 3 and thereafter. Thus, PC have a plasma FFA pool available continuously for oxidation during storage. Studies with radiolabeled palmitate suggested that FFA oxidation by platelets occurs during storage. The current findings show that plasma FFA could be a significant substrate for oxidative metabolism during storage of PC and that the oxidized FFA are replenished at least in part from plasma. These results may allow platelet storage to be improved, particularly in synthetic media. PMID:3629676

  5. Freezing of Apheresis Platelet Concentrates in 6% Dimethyl Sulfoxide: The First Preliminary Study in Turkey

    PubMed Central

    Yılmaz, Soner; Çetinkaya, Rıza Aytaç; Eker, İbrahim; Ünlü, Aytekin; Uyanık, Metin; Tapan, Serkan; Pekoğlu, Ahmet; Pekel, Aysel; Erkmen, Birgül; Muşabak, Uğur; Yılmaz, Sebahattin; Avcı, İsmail Yaşar; Avcu, Ferit; Kürekçi, Emin; Eyigün, Can Polat

    2016-01-01

    Objective: Transfusion of platelet suspensions is an essential part of patient care for certain clinical indications. In this pioneering study in Turkey, we aimed to assess the in vitro hemostatic functions of platelets after cryopreservation. Materials and Methods: Seven units of platelet concentrates were obtained by apheresis. Each apheresis platelet concentrate (APC) was divided into 2 equal volumes and frozen with 6% dimethyl sulfoxide (DMSO). The 14 frozen units of APCs were kept at -80 °C for 1 day. APCs were thawed at 37 °C and diluted either with autologous plasma or 0.9% NaCl. The volume and residual numbers of leukocytes and platelets were tested in both before-freezing and post-thawing periods. Aggregation and thrombin generation tests were used to analyze the in vitro hemostatic functions of platelets. Flow-cytometric analysis was used to assess the presence of frozen treated platelets and their viability. Results: The residual number of leukocytes in both dilution groups was <1x106. The mean platelet recovery rate in the plasma-diluted group (88.1±9.5%) was higher than that in the 0.9% NaCl-diluted group (63±10%). These results were compatible with the European Directorate for the Quality of Medicines quality criteria. Expectedly, there was no aggregation response to platelet aggregation test. The mean thrombin generation potential of post-thaw APCs was higher in the plasma-diluted group (2411 nmol/L per minute) when compared to both the 0.9% NaCl-diluted group (1913 nmol/L per minute) and the before-freezing period (1681 nmol/L per minute). The flow-cytometric analysis results for the viability of APCs after cryopreservation were 94.9% and 96.6% in the plasma and 0.9% NaCl groups, respectively. Conclusion: Cryopreservation of platelets with 6% DMSO and storage at -80 °C increases their shelf life from 7 days to 2 years. Besides the increase in hemostatic functions of platelets, the cryopreservation process also does not affect their viability

  6. Preparation of small volume, leuko and erythrocyte very poor platelet concentrates.

    PubMed

    Valbonesi, M; Angelini, G; Malfanti, L; Lercari, G; Fella, M; Calderisi, S; Anselmo, A; Balistreri, M

    1986-05-01

    Recently developed automated discontinuous flow centrifuge (DFC) separators can produce leuko- and erythrocyte-poor platelet concentrates (PC). According to general experience with these machines it is difficult to obtain more than 4 X 10(11) platelets, though a second program set up by Coffe et al. appears to produce PC containing approximately 5 X 10(11) platelets suspended in a plasma volume of 390 ml. At our center we employed a new Dideco cell separator equipped with the surge pump and a technique developed for the production of small volume, RBC and WBC-very poor PC. In 60 routine procedures we obtained the following results: mean processing time 87 +/- 11 minutes; final volume of PC 136 +/- 19 ml, with a mean platelet yield of 5.21 X 10(11) platelets. WBC contamination was 1.8 X 10(8) (93% lymphocytes) and RBC were 3.1 X 10(8). Plasma volume as well as WBC and RBC contamination were reduced by recirculating PC after the 6th pass. The demand for single donor platelet concentrates (PC) is increasing progressively. Recently developed automated cell separators can produce leukocyte (WBC) and erythrocyte (RBC) poor PC. With these machines it may be difficult to obtain PC containing at least 4 X 10(11) platelets and less than 1 X 10(9) leukocytes (1, 2, 3) since donor variables such as hematocrit, precounts, buffy coat formation and initial plasma light transmission are of paramount importance for the efficiency of the program. At our center a prototype discontinuous flow centrifuge (DFC) cell separator equipped with the surge pump was studied.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3733246

  7. Platelet lysate from whole blood-derived pooled platelet concentrates and apheresis-derived platelet concentrates for the isolation and expansion of human bone marrow mesenchymal stromal cells: production process, content and identification of active components

    PubMed Central

    Fekete, Natalie; Gadelorge, Mélanie; Fürst, Daniel; Maurer, Caroline; Dausend, Julia; Fleury-Cappellesso, Sandrine; Mailänder, Volker; Lotfi, Ramin; Ignatius, Anita; Sensebé, Luc; Bourin, Philippe; Schrezenmeier, Hubert; Rojewski, Markus Thomas

    2012-01-01

    Background aims The clinical use of human mesenchymal stromal cells (MSC) requires ex vivo expansion in media containing supplements such as fetal bovine serum or, alternatively, human platelet lysate (PL). Methods Platelet concentrates were frozen, quarantine stored, thawed and sterile filtered to obtain PL. PL content and its effect on fibroblast-colony-forming unit (CFU-F) formation, MSC proliferation and large-scale expansion were studied. Results PL contained high levels of basic fibroblast growth factor (bFGF), soluble CD40L (sCD40L), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), platelet-derived growth factor AA (PDGF-AA), platelet-derived growth factor AB/BB (PDGF-AB/BB), chemokine (C-C) ligand 5 (CCL5; RANTES) transforming growth factor-β1 (TGF-β1) and chemokine (C-X-C) ligand 1/2/3 (GRO), with low batch-to-batch variability, and most were stable for up to 14 days. Inhibition of PDGF-BB and bFGF decreased MSC proliferation by about 20% and 50%, respectively. The strongest inhibition (about 75%) was observed with a combination of anti-bFGF + anti-PDGF-BB and anti-bFGF + anti-TGF-β1 + anti-PDGF-BB. Interestingly, various combinations of recombinant PDGF-BB, bFGF and TGF-β1 were not sufficient to promote cell proliferation. PL from whole blood-derived pooled platelet concentrates and apheresis platelet concentrates did not differ significantly in their growth-promoting activity on MSC. Conclusions PL enhances MSC proliferation and can be regarded as a safe tool for MSC expansion for clinical purposes. \\in particular, PDGF-BB and bFGF are essential components for the growth-promoting effect of PL, but are not sufficient for MSC proliferation. PMID:22296115

  8. 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

  9. EFFECT OF PHOTOPERIOD ON PLATELET-ACTIVATING FACTOR CONCENTRATION IN BOAR SPERMATOZOA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Platelet-activating factor (PAF, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is an important phospholipid mediator shown to be involved in fertilization. We recently reported that boars with a 70% or higher fertility history have a higher concentration of PAF in their spermatozoa. In addition,...

  10. 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

  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. Von Willebrand factor availability in platelet concentrates stored for 5 days.

    PubMed

    Cesar, J M; García-Avello, A; Monteagudo, J; Espinosa, J I; Lodos, J C; Castillo, R; Navarro, J L

    1994-02-01

    Von Willebrand factor (vWF) availability was assessed in platelet concentrates (PCs). After 5 days of storage, 82 +/- 9% of basal levels of ristocetin cofactor activity (vWF:RCo) remained in PCs. vWF antigen (vWF:Ag) increased up to 166 +/- 38% (P < 0.05) in the same period. Autoradiograph pattern of vW:Ag showed an increase in low molecular weight multimers, and fast migrating multimeric forms were visualized by crossed immunoelectrophoresis on day 5. Studies carried out in platelet free plasma stored as PCs showed similar changes in vWF:RCo but increments in vWF:Ag were not detected. These data indicate that PCs maintain vWF:RCo levels of clinical value even after 5 days of storage and suggest that vWF comes out from platelets to plasma during storage. PMID:8141116

  13. Effect of membrane protein concentration on binding of /sup 3/H-imipramine in human platelets

    SciTech Connect

    Barkai, A.I.; Kowalik, S.; Baron, M.

    1985-02-01

    Binding of /sup 3/H-imipramine to platelet membranes has been implicated as a marker for depression. Comparing /sup 3/H-IMI binding between depressed patients and normal subjects we observed an increase in the dissociation constant Kd with increasing membrane protein. This phenomenon was studied more rigorously in five normal subjects. Platelet membranes were prepared and adjusted to four concentrations of protein ranging from 100 to 800 micrograms/ml. The /sup 3/H-IMI binding parameters of maximum binding sites number (Bmax) and Kd were obtained by Scatchard analysis at each membrane concentration. A positive linear relationship was found between K/sub d/ values and the concentration of membrane protein in the assay, but no change was observed in Bmax. The variability in Kd values reported in the literature may be accounted for in part by the different concentrations of membrane protein used in various studies.

  14. Evaluation of platelet function using the in vitro bleeding time and corrected count increment of transfused platelets. Comparison between platelet concentrates derived from pooled buffy coates and apheresis.

    PubMed

    Eriksson, L; Kristensen, J; Olsson, K; Bring, J; Högman, C F

    1996-01-01

    The functional capacity of transfused platelets was evaluated with in vitro bleeding time (IVBT) and corrected count increment (CCI) in order to compare platelet concentrates (PCs) derived from pooled buffy coats (BC-PCs) with PCs collected by apheresis (A-PCs). The suspension medium in the BC-PCs was 30% CPD plasma and 70% of an additive solution (containing sodium and potassium chloride, sodium citrate and phosphate, mannitol), and in the A-PCs the medium was 100% CPD plasma. IVBT was evaluated using a Thrombostat 4000/2. BC-PC and A-PC were transfused 57 and 41 times, respectively to 36 patients with chemotherapy-induced thrombocytopenia. PCs transfused within 2 days of donation were considered fresh, and those transfused within 3-5 days were considered stored. IVBT was determined before, as well as 10-30 min and 24 h after transfusion; CCI was determined 10-30 min and 24 h after transfusion. The median pretransfusion IVBT value was 486 s. It was measurable in 21 of 98 (21%) of the transfusions, i.e. below the cutoff limit of 486 s. Ten to 30 min after transfusion, the IVBT showed a measurable reduction in 90% of the transfusions with fresh BC-PCs, 92% of those with fresh a-PCs, 63% of those with stored BC-PCs and 79% of those with stored A-PCs. After 24 h, the corresponding values were 63% for fresh BC-PCs, 50% for fresh A-PCs, 26% for stored BC-PCs and 38% for stored A-PCs. The median value of CCI 10-30 min after transfusion was 20 for fresh BC-PCs, 17 for fresh A-PCs, 16 for stored BC-PCs and 14 for stored A-PCs. The difference in IVBT between fresh and stored BC-PCs was significant (p = 0.032), unlike that between fresh and stored A-PC. After 24 h the corresponding values were 7 for fresh BC-PCs, 4 for fresh A-PCs, 4 for stored BC-PCs and 3 for stored A-PCs. When all transfusions with fresh PCs (BC-PCs + A-PCs) were compared with all transfusions with stored PCs, a statistical difference was demonstrated in both CCI (p = 0.027) and IVBT (p = 0.043). Spearman

  15. Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses

    NASA Astrophysics Data System (ADS)

    Zhan, Fan; Fan, Yu-Bo; Deng, Xiao-Yan

    2011-10-01

    Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the wall. In our previous studies, it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end anastomoses. In order to better understand the beneficial effect of the swirling flow, we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow conditions. The numerical models were created based on our previous experimental studies. The simulation results revealed that when compared with the normal flow, the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion tube. The present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts, or in end-to-end anastomoses as observed in our previous experimental study, was possibly through a mechanism of platelet transport, in which the swirling flow reduced the near-wall concentration of platelets.

  16. Adenosine diphosphate-induced aggregation of human platelets in flow through tubes. I. Measurement of concentration and size of single platelets and aggregates.

    PubMed Central

    Bell, D N; Spain, S; Goldsmith, H L

    1989-01-01

    A double infusion flow system and particle sizing technique were developed to study the effect of time and shear rate on adenosine diphosphate-induced platelet aggregation in Poiseuille flow. Citrated platelet-rich plasma, PRP, and 2 microM ADP were simultaneously infused into a 40-microliters cylindrical mixing chamber at a fixed flow ratio, PRP/ADP = 9:1. After rapid mixing by a rotating magnetic stirbar, the platelet suspension flowed through 1.19 or 0.76 mm i.d. polyethylene tubing for mean transit times, t, from 0.1 to 86 s, over a range of mean tube shear rate, G, from 41.9 to 1,000 s-1. Known volumes of suspension were collected into 0.5% buffered glutaraldehyde, and all particles in the volume range 1-10(5) microns 3 were counted and sized using a model ZM particle counter (Coulter Electronics Inc., Hialeah, FL) and a logarithmic amplifier. The decrease in the single platelet concentration served as an overall index of aggregation. The decrease in the total particle concentration was used to calculate the collision capture efficiency during the early stages of aggregation, and aggregate growth was followed by changes in the volume fraction of particles of successively increasing size. Preliminary results demonstrate that both collision efficiency and particle volume fraction reveal important aspects of the aggregation process not indicated by changes in the single platelet concentration alone. PMID:2605298

  17. Effect of an Activated Platelet Concentrate on Differentiated Cells Involved in Tissue Healing.

    PubMed

    Brini, Anna T; Ceci, Caterina; Taschieri, Silvio; Niada, Stefania; Lolato, Alessandra; Giannasi, Chiara; Mortellaro, Carmen; Del Fabbro, Massimo

    2016-05-01

    Tissue healing is a complex process involving several players such as cells and growth factors released from platelets upon activation. Today, platelet concentrates (PCs) are used in many different medical fields including oral, orthopaedic, and reconstructive surgery since they allow growth factors delivery to the injured site, aiming at enhancing tissue regeneration. The purpose of this in vitro study was to evaluate the effect of the acellular plasma of an activated platelet concentrate obtained using a manual protocol, on the proliferation, and biological activity of differentiated cells involved in tissue healing. Human osteoblasts and dermal fibroblasts were grown in serum-free medium supplemented with PC derived from several donors. Human osteoblast and human dermal fibroblast proliferation was assessed by MTT test after 7 days and cells were count up to 12-day incubation. Human osteoblast osteo-differentiation was tested after 7 and 14-day incubation by alkaline phosphatase assay. The addition of PC to the culture medium caused an increased proliferation with respect to cells grown in standard condition. The results of the present study suggest that PC supports the proliferation of terminally differentiated cells involved in wound healing and tissue regeneration, confirming its beneficial clinical application in regenerative therapies. PMID:27054419

  18. First autoclave-sterilized platelet-additive solution containing glucose with a physiological pH for the preparation of plasma-poor platelet concentrates.

    PubMed

    Shimizu, T; Shibata, K; Kora, S

    1992-01-01

    The glucose-free platelet-additive solution (termed AR solution), developed by Adams and Rock [Transfusion 1988;28:217-220], was modified by adding glucose as an energy substrate for platelets and maltose to prevent platelet lysis and by replacing sodium gluconate with sodium phosphate for better pH maintenance. The new platelet-additive solution (termed Seto solution) contained 90 mM NaCl, 5 mM KCl, 3 mM MgCl2, 17 mM tri-sodium citrate, 4.9 mM NaH2PO4, 20.1 mM Na2HPO4, 23 mM sodium acetate, 28.8 mM maltose, and 23.5 mM glucose with a pH of 7.4. The solution was sterilized by autoclaving in plastic bags in nitrogen to prevent glucose caramelization at high pH. Plasma-poor platelet concentrates prepared by adding Seto solution to the pelleted platelet buttons were stored in a LE-2 polyolefin bag at 22 degrees C with constant agitation for 5 days. The platelets suspended in Seto solution maintained oxygen consumption at a rate of 1.1 nmol/min/10(9) platelets after 5-day storage, with glucose consumption and lactate production rates of 0.5 +/- 0.2 and 1.2 +/- 0.2 nmol/min/10(9) platelets, respectively. This resulted in a final mean pH of 7.0. Those suspended in AR solution ceased glycolysis within 3 days because residual plasma glucose had been consumed. This was associated with decreases in percent hypotonic shock response and aggregation induced by adenosine diphosphate and collagen. Lactate dehydrogenase discharge in AR solution was 5 and 8 times higher at day 3 and day 5, respectively, than that of Seto solution. Morphologically, there were no ballooned platelets after storage in Seto solution.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1519373

  19. Platelet concentrates for revitalization of immature necrotic teeth: a systematic review of the clinical studies.

    PubMed

    Lolato, Alessandra; Bucchi, Cristina; Taschieri, Silvio; Kabbaney, Ahmed El; Fabbro, Massimo Del

    2016-07-01

    This systematic review aimed at determining the effectiveness of autologous platelet concentrate (APC) in the treatment of immature necrotic teeth. An electronic search was performed on MEDLINE, Embase, Scopus, SciELO, Lilacs, CENTRAL. Comparative clinical studies were included, in which APC was tested for pulp regeneration and radicular development. Selected articles underwent risk-of-bias assessment. Clinical and radiographic outcomes were considered. Three randomized parallel studies and one split-mouth case series were included. One study had low risk of bias and three studies had high risk. A total of 61 immature necrotic teeth were treated in 56 patients. Follow-up ranged between 12 and 18 months. All studies used platelet-rich plasma (PRP) in the test group, and one also used platelet-rich fibrin (PRF). After treatment, all teeth of control and experimental groups remained asymptomatic for the entire study duration. Only one study reported response to cold and electric pulp test, showing not significantly better outcomes for the test group. Similarly, periapical healing and apical closure were improved in the group treated with APC although statistical significance was not achieved (P = 0.08 and P = 0.06, respectively), probably due to the limited sample size. The teeth treated with PRP achieved significantly better thickening of the dentin walls (P = 0.01), and root lengthening (P = 0.001) than control teeth. Despite the potential effectiveness of APC in promoting root development of necrotic immature teeth, scarce evidence exists regarding this subject. In the studies evaluated in this review, platelet concentrates showed promising results that warrant further investigation. PMID:26836782

  20. Mathematical analysis of mural thrombogenesis. Concentration profiles of platelet-activating agents and effects of viscous shear flow.

    PubMed Central

    Folie, B J; McIntire, L V

    1989-01-01

    The concentration profiles of adenosine diphosphate (ADP), thromboxane A2 (TxA2), thrombin, and von Willebrand factor (vWF) released extracellularly from the platelet granules or produced metabolically on the platelet membrane during thrombus growth, were estimated using finite element simulation of blood flow over model thrombi of various shapes and dimensions. The wall fluxes of these platelet-activating agents were estimated for each model thrombus at three different wall shear rates (100 s-1, 800 s-1, and 1,500 s-1), employing experimental data on thrombus growth rates and sizes. For that purpose, whole human blood was perfused in a parallel-plate flow chamber coated with type l fibrillar human collagen, and the kinetic data collected and analyzed by an EPl-fluorescence video microscopy system and a digital image processor. It was found that thrombin concentrations were large enough to cause irreversible platelet aggregation. Although heparin significantly accelerated thrombin inhibition by antithrombin lll, the remaining thrombin levels were still significantly above the minimum threshold required for irreversible platelet aggregation. While ADP concentrations were large enough to cause irreversible platelet aggregation at low shear rates and for small aggregate sizes, TxA2 concentrations were only sufficient to induce platelet shape change over the entire range of wall shear rates and thrombi dimensions studied. Our results also indicated that the local concentration of vWF multimers released from the platelet alpha-granules could be sufficient to modulate platelet aggregation at low and intermediate wall shear rates (less than 1,000 s-1). The sizes of standing vortices formed adjacent to a growing aggregate and the embolizing stresses and the torque, acting at the aggregate surface, were also estimated in this simulation. It was found that standing vortices developed on both sides of the thrombus even at low wall shear rates. Their sizes increased with

  1. Storage of platelet concentrates after high-dose ultraviolet B irradiation

    SciTech Connect

    Snyder, E.L.; Beardsley, D.S.; Smith, B.R.; Horne, W.; Johnson, R.; Wooten, T.; Napychank, P.A.; Male, P.; Buchholz, D.H. )

    1991-07-01

    Ultraviolet B (UVB) irradiation of platelet concentrates (PCs) may prevent the development of posttransfusion HLA alloimmunization. As irradiation performed in a blood center or a hospital will probably be associated with a variable postirradiation delay before transfusion, the ability to store PCs after UVB irradiation becomes important. The effects have been studied of a UVB dose of 10,000 mJ per cm2, the dose used in our institution for UVB clinical trials, on PCs pooled and stored for up to 96 hours after irradiation. Results showed that after 96 hours of storage, though there were no changes in pH, platelet count, white cell count, percent discharge of lactate dehydrogenase, or {beta}-thromboglobulin, there were significant decreases in morphology score and osmotic recovery. These changes, however, were not evident after 24 hours of storage. Similarly, there was a 60% decrease in immunoreactive membrane glycoprotein (GP) Ib after 96 hours of storage, but these changes were not seen after 48 hours of storage. No changes were seen in levels of GPIIb/IIIa in either group during the 96 hours of storage. On computer-analyzed two-dimensional polyacrylamide gel electrophoresis, PCs irradiated at 10,000 mJ per cm2 and stored for 72 hours had changes in over 50 platelet proteins as compared to those proteins in nonirradiated age-matched control PCs. It can be concluded that UVB irradiation of PCs at 10,000 mJ per cm2 does not lead to significant platelet deterioration after short-term storage (24-48 hours) but is likely to be deleterious after long-term (72-96 hours) storage.

  2. Detection and Identification of Platelet-Associated Alloantibodies by a Solid-Phase Modified Antigen Capture Elisa (MACE) Technique and Its Correlation to Platelet Refractoriness in Multi platelet Concentrate Transfused Patients.

    PubMed

    Sarkar, R S; Philip, J; Jain, Neelesh

    2015-03-01

    Platelets express glycoproteins (IIb/IIIa, Ib/IX, Ia/IIa, IV, and HLA-1) that are polymorphic and can become targets for antibody responses. Patients at threat are those who received multiple platelet transfusions. Modified antigen capture elisa (MACE) is a qualitative solid phase Elisa designed to detect IgG antibodies against platelet specific antigens. The study has been carried out over a period of 2 years. A total of 100 patients were selected, who had been transfused with at least 15 units of platelet concentrate. All patients were having either hematological malignancies or bone marrow failure syndromes. Platelet antibodies were identified using MACE-1&2. Data was analysed statistically, using odds ratio (OR) with 95 % confidence interval. 39 % of the patients were found to be alloimmunized against platelet antigens, of which eleven showed refractoriness. Six patients (54.5 %) with HLA-1, two patients (9.5 %) with GPIb/IX, two patients (40 %) with both HLA-1 and GPIIb/IIIa, and one patient with GPIIb/IIIa antibodies showed refractoriness. Production of HLA-1 antibody and the development of refractoriness was found to be significant with OR 14.05 and P value 0.0025. MACE-1&2 enabled specific detection and identification of platelet antibodies, which in turn correlated well with the development of refractoriness in multi transfused patients. GPIb/IX was detected as the commonest antibody in our patient population, which is in variance with Europian studies where it is GPIa/IIIa (HPA-1a/5b). This technique should be utilised in patients who are at an increased risk of developing alloimmunisation due to repeated platelet transfusions. PMID:25548450

  3. Micro-concentration Lipopolysaccharide as a Novel Stimulator of Megakaryocytopoiesis that Synergizes with IL-6 for Platelet Production

    PubMed Central

    Wu, Di; Xie, Jun; Wang, Xuejun; Zou, Bingcheng; Yu, Yin; Jing, Tao; Zhang, Songmei; Zhang, Qing

    2015-01-01

    Lipopolysaccharide (LPS) induces platelet activation and enhances platelet sensitivity to aggregation, which might alter platelet counts. We found that serial doses of micro-concentration LPS significantly increased the platelet count in mice treated with kanamycin, along with increased expression of IL-6 compared with IL-3 and TPO in megakaryocytes obtained from the mouse bone morrow following LPS administration. Furthermore, LPS at lower levels ranging plus IL-6 effectively stimulated CFU-MK formation and increased CD41 expression and megakaryocyte polyploidization. Meanwhile, there was a sustained rise in the percentage of reticulated platelets in the whole blood in response to low-dosage LPS combined with IL-6. In vivo experiments also demonstrated that the administration of LPS combined with IL-6 substantially enhanced the number of circulating platelets in normal and thrombocytopenic mice. Notably, the optimal LPS concentration in combination with IL-6 might be a novel stimulator of TLR4 and IL-6R expression in Dami cell lines, which initially occurs through TLR4-IL-6R crosstalk and then involves the activation of NF-κB and phosphorylation of p38 MAPK. These data suggest a new paradigm for the regulation of megakaryocytopoiesis and platelet production via a synergistic effect of LPS and IL-6, which has the potential to be used for the design of new therapies. PMID:26330186

  4. 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

  5. Quality of pooled platelet concentrates prepared from buffy coats and stored in an additive solution after filtration.

    PubMed

    Koerner, K; Weihe, R; Sahlmen, P; Zeller, B; Seifried, E; Cardoso, M; Kubanek, B

    1995-02-01

    Platelet concentrates prepared from buffy coat were pooled and stored for 6 days after removal of leukocytes by filtration. The platelets were stored in plasma or in an additive solution, Plasmalyte-A. In vitro platelet function was better preserved using Plasmalyte-A than plasma with regard to osmotic reversal and aggregation. No significant differences for the release of platelet markers beta-thromboglobulin, platelet factor 4, or lactate dehydrogenase pre- and post-filtration and storage in plasma or Plasmalyte-A was observed. Expression of the surface membrane glycoproteins Ib, Ia/IIa, IIb/IIIa, and IV measured by flow cytometry after binding of monoclonal antibodies did not change during storage. The expression of activation-dependent alpha-granula glycoprotein GMP140, the thrombospondin, and the glycoprotein 53 from the lysosomal granules was not different between platelet pools stored in plasma or in Plasmalyte-A. The in vitro quality of platelets stored as pools is comparable for plasma and the additive solution Plasmalyte-A. PMID:7880932

  6. Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates

    NASA Astrophysics Data System (ADS)

    Corash, Laurence; Lin, Lily; Wiesehahn, Gary; Cimino, George

    1992-06-01

    Transmission of viral diseases through blood products remains a problem in transfusion medicine. A number of methods have been developed to inactivate viral pathogens in plasma and plasma fractions, including: dry heating, wet heating, solvent-detergent treatment, and immunoaffinity purification. While some of these methods successfully inactivate pathogenic viruses, inactivation may be incomplete or result in damage to labile plasma proteins and cells. We have developed a photochemical decontamination system (PCD) for platelet concentrates (PC) utilizing treatment with long wavelength ultraviolet radiation (UVA, 320 - 400 nm) and 8-methoxypsoralen (8-MOP). This system is capable of inactivating 25 - 30 logs/hr of bacteria E. coli or S. aureus, 6 logs/hr of bacteriophage fd, 0.9 log/hr of bacteriophage R17 and 1.1 logs/hr of feline leukemia virus (FeLV) in PC. Immediately following 6 hrs of PCD treatment, platelet integrity and function of PCD treated and control PC were equivalent. After overnight storage PCD treated and control PC platelet properties were equal, but there was a slight reduction in TXB-2 production of PCD treated PC compared to controls. Following PCD treatment, PC were stored for 48 to 96 hrs. Platelet counts, morphology scores, extracellular LDH levels, aggregation response, dense body (db) content, and alpha granule ((alpha) g) content of PCD treated and control PC were comparable. We assessed the ability of the PCD technique to inactivate intracellular and extracellular virus, quantified the degree of DNA adduct formation in contaminating lymphocytes, and measured the inhibition of polymerase chain reaction (PCR) mediated amplification of intracellular DNA. High titers of cell-free murine cytomegalovirus added to human platelet concentrates (final concentration 106) were inactivated by PCD within 30 min. Cat renal fibroblasts infected at high levels with feline rhinotracheitis virus (FeRTV) were seeded into PC followed by PCD treatment with

  7. Detection of bacterial contamination in platelet concentrates using flow cytometry and real-time PCR methods.

    PubMed

    Vollmer, Tanja; Kleesiek, Knut; Dreier, Jens

    2013-01-01

    Despite considerable advances in the safety of blood components based on the application of highly sensitive and specific screening methods to minimize the viral infection risk, the prevention of transfusion-associated bacterial infection remains a major challenge in transfusion medicine. In particular, platelet concentrates represent the greatest infectious risk of transfusion-transmitted bacterial sepsis. The detection of bacterial contamination in platelet concentrates has been implemented in several blood services as a routine quality control testing. Although culture is likely to remain the gold standard method of detecting bacterial contamination, the use of rapid methods is likely to increase and play an important role in transfusion medicine in the future. In particular, flow cytometric methods and nucleic acid amplification techniques are powerful tools in bacterial screening assays. Compared to culture-based methods, the combination of high sensitivity and specificity, low contamination risk, ease of performance, and speed has made those technologies appealing alternatives to conventional culture-based testing methods. PMID:23104283

  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. Intramammary administration of platelet concentrate as an unconventional therapy in bovine mastitis: first clinical application.

    PubMed

    Lange-Consiglio, A; Spelta, C; Garlappi, R; Luini, M; Cremonesi, F

    2014-10-01

    Bovine udder infections induce a variety of changes in gene expression of different growth factors that may suggest their possible role in glandular tissue protection or repair processes. Growth factors and also chemokines and cytokines may act synergistically to increase the infiltration of neutrophils and macrophages to promote angiogenesis, fibroplasia, matrix deposition, and, ultimately, re-epithelialization. Considering the vast applications, typically in human medicine, of platelet concentrate (PC) and its ease of preparation, the aim of our study was to evaluate an alternative therapy to stimulate the regeneration of glandular tissue, administering a concentration in excess of the growth factors contained in the PC. In each one of the 3 farms examined in the trial, PC was prepared from donor cows in good health, free from infections, and with no records of medications administered during the previous 2 mo. The platelet produced in one farm was used only for treating the cows of the same farm in a heterologous way. A total of 229 mastitic quarters were divided in 3 groups: antibiotic group (treated with intramammary antibiotic), antibiotic and PC group (treated intramammarily with antibiotics in association with PC), and PC group (treated with intramammary PC alone). The diagnosis of mastitis was based on somatic cell count and bacteriological evaluation of the milk from the affected quarter. Platelet concentrate, alone or in association with antibiotic, was used for 3 consecutive days as an unconventional therapy in bovine acute and chronic mastitis. Our data show that the associated action of antibiotic and PC performed significantly better than the antibiotic alone, either for the recovery of the affected mammary quarters or for somatic cell count reduction. In the same way, the association antibiotic plus PC showed significantly fewer relapses compared with the antibiotic alone, either for acute or chronic mastitis. The treatment with only PC did not show

  10. Comparison between the effects of platelet-rich plasma and bone marrow concentrate on defect consolidation in the rabbit tibia

    PubMed Central

    Batista, Marco Antonio; Leivas, Tomaz Puga; Rodrigues, Consuelo Junqueira; Arenas, Géssica Cantadori Funes; Belitardo, Donizeti Rodrigues; Guarniero, Roberto

    2011-01-01

    OBJECTIVE: To perform a comparative analysis of the effects of platelet-rich plasma and centrifuged bone marrow aspirate on the induction of bone healing in rabbits. METHOD: Twenty adult, male New Zealand rabbits were randomly separated into two equal groups, and surgery was performed to create a bone defect (a cortical orifice 3.3 mm in diameter) in the proximal metaphysis of each rabbit's right tibia. In the first group, platelet-rich plasma was implanted in combination with β-tricalcium phosphate (platelet-rich plasma group), and in the second group, centrifuged bone marrow in combination with β-tricalcium phosphate (centrifuged bone marrow group) was implanted. After a period of four weeks, the animals were euthanized, and the tibias were evaluated using digital radiography, computed tomography, and histomorphometry. RESULTS: Seven samples from each group were evaluated. The radiographic evaluation confirmed the absence of fractures in the postoperative limb and identified whether bone consolidation had occurred. The tomographic evaluation revealed a greater amount of consolidation and the formation of a greater cortical bone thickness in the platelet-rich plasma group. The histomorphometry revealed a greater bone density in the platelet-rich plasma group compared with the centrifuged bone marrow group. CONCLUSION: After four weeks, the platelet-rich plasma promoted a greater amount of bone consolidation than the bone marrow aspirate concentrate. PMID:22012052

  11. Comparison of the effect of calcium gluconate and batroxobin on the release of transforming growth factor beta 1 in canine platelet concentrates

    PubMed Central

    2012-01-01

    Background The clinical use of autologous platelet concentrates (also known as platelet-rich plasma) on the field of regenerative therapy, in the last decade has been the subject of several studies especially in equine medicine and surgery. The objectives of this study was: 1) to describe and compare the cellular population in whole blood, lower fraction (A) and upper fraction (B) of platelet concentrates, 2) to measure and compare the transforming growth factor beta 1 (TGF-β1) concentration in plasma and both platelet concentrates after be activated with calcium gluconate or batroxobin plus calcium gluconate and, 3) to determine correlations between cell counts in platelet concentrates and concentrations of TGF-β1. Blood samples were taken from 16 dogs for complete blood count, plasma collection and platelet concentrates preparation. The platelet concentrates (PC) were arbitrarily divided into two fractions, specifically, PC-A (lower fraction) and PC-B (upper fraction). The Platelet concentrates were analyzed by hemogram. After activated with calcium gluconate or batroxobin plus calcium gluconate, TGF-β1 concentration was determined in supernatants of platelet concentrates and plasma. Results There were differences statistically significant (P < 0.05) for the platelet count and leukocyte count and TGF-β1 concentration between whole blood, plasma and both platelet concentrates. A significant correlation was found between the number of platelets in both platelet concentrates and TGF-β1 concentration. Platelet collection efficiency was 46.34% and 28.16% for PC-A and PC-B, respectively. TGF-β1 concentration efficiency for PC activated with calcium gluconate was 47.75% and 31.77%, for PC-A and PC-B, respectively. PC activated with batroxobin plus CG showed 46.87% and 32.24% for PC-A and PC-B, respectively. Conclusions The methodology used in this study allows the concentration of a number of platelets and TGF-β1 that might be acceptable for a biological

  12. Feasibility for EGRET detection of antimatter concentrations in the universe

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.

    1990-01-01

    Although the Grand Unified Theories of elementary particle dynamics have to some extent reduced the aesthetic attraction of matter-antimatter symmetry in the Universe, the idea is still not ruled out. Although first introduced by Alfven (1965), most of the theoretical development related to gamma-ray astronomy was carried out by Stecker, who has proposed (Stecker, Morgan, and Bredekamp, 1971) matter-antimatter annihilation extending back to large redshifts as a possible explanation of the apparently extragalactic diffuse gamma radiation. Other candidate explanations were also proposed, such as superposition of extragalactic discrete sources. Clearly, the existence of significant amounts of antimatter in the universe would be of great cosmological importance; its detection, however, is not simple. Since the photon is its own antiparticle, it carries no signature identifying whether it originated in a matter or an antimatter process; even aggregates of photons (spectra) are expected to be identical from matter and antimatter processes. The only likely indicator of the presence of concentrations of antimatter is evidence of its annihilation with normal matter, assuming there is some region of contact or overlap. The EGRET (Energetic Gamma-Ray Experimental Telescope) on the Gamma Ray Observatory, with a substantial increase in sensitivity compared with earlier high energy gamma ray telescopes, may be able to address this issue. The feasibility of using EGRET in such a search for antimatter annihilation in the Universe is considered.

  13. Autologous keratinocyte suspension in platelet concentrate accelerates and enhances wound healing – a prospective randomized clinical trial on skin graft donor sites: platelet concentrate and keratinocytes on donor sites

    PubMed Central

    2013-01-01

    Background Wound healing involves complex mechanisms, which, if properly chaperoned, can enhance patient recovery. The abilities of platelets and keratinocytes may be harnessed in order to stimulate wound healing through the formation of platelet clots, the release of several growth factors and cytokines, and cell proliferation. The aim of the study was to test whether autologous keratinocyte suspensions in platelet concentrate would improve wound healing. The study was conducted at the Lausanne University Hospital, Switzerland in 45 patients, randomized to three different topical treatment groups: standard treatment serving as control, autologous platelet concentrate (PC) and keratinocytes suspended in autologous platelet concentrate (PC + K). Split thickness skin graft donor sites were chosen on the anterolateral thighs of patients undergoing plastic surgery for a variety of defects. Wound healing was assessed by the duration and quality of the healing process. Pain intensity was evaluated at day five. Results Healing time was reduced from 13.9 ± 0.5 days (mean ± SEM) in the control group to 7.2 ± 0.2 days in the PC group (P < 0.01). An addition of keratinocytes in suspension further reduced the healing time to 5.7 ± 0.2 days. Pain was reduced in both the PC and PC + K groups. Data showed a statistically detectable advantage of using PC + K over PC alone (P < 0.01). Conclusion The results demonstrate the positive contribution of autologous platelets combined with keratinocytes in stimulating wound healing and reducing pain. This strikingly simple approach could have a significant impact on patient care, especially critically burned victims for whom time is of the essence. Clinical trial registry information Protocol Record Identification Number: 132/03 Registry URL: http://www.clinicaltrials.gov PMID:23570605

  14. Comparative analysis of platelet 5-HT concentrations in Han and Li patients with post-traumatic stress disorder.

    PubMed

    Li, L; Li, M X; Pan, L H; Wang, G M; Guo, M; Fu, L Q; Guo, J C; Gao, Y S; Chen, F; Xie, M X

    2016-01-01

    We investigated the role of serotonin (5-HT) in the pathogenesis of post-traumatic stress disorder (PTSD) by determining the platelet 5-HT concentrations in Li and Han patients with PTSD in Hainan Province, China. Li and Han control groups of the same sample size have no statistical differences in gender and age distribution compared to those in the PTSD groups who were also examined. The platelet 5-HT concentrations were determined by high-performance liquid chromatography. In addition, the patients and controls were evaluated by the impact of event scale-revised (IES-R). IES-R showed that the total and sub-scale scores of three factors (avoidance, intrusion, and hyperarousal) of Li patients with PTSD were significantly higher than those of Han patients with PTSD. Scores of both PTSD groups were higher than those of their respective control groups. The platelet 5-HT concentration of the Li patients with PTSD (120.56 ± 118.05 ng/10(9) platelets) was lower than that of the Han patients with PTSD (271.43 ± 181.66 ng/10(9) platelets) and that of both Li and Han control groups (338.54 ± 156.46, 350.58 ± 169.19 ng/10(9) platelets, respectively). Differences existed in symptoms of PTSD in terms of avoidance, intrusion, and hyperarousal in the Li and Han patients with PTSD. The diminished 5-HT activity in patients with PTSD may be relevant to biochemical changes in the brain and body. The differences in these factors between ethnic groups could be due to their customs, social status, and culture. PMID:27525843

  15. Quality of platelet concentrates irradiated with UVB light: effect of UV dose and dose rate on glycocalicin release and correlation with other markers of the platelet storage lesion.

    PubMed

    Bessos, H; Murphy, W G; Robertson, A; Vickers, M; Seghatchian, M J; Tandy, N P; Cutts, M; Pamphilon, D H

    1993-06-01

    The amount of membrane-associated glycoprotein Ib in platelet concentrates (PCs) irradiated with a high dose of UVB light has been shown to be significantly reduced after 48 h storage. We recently corroborated this finding when we noted an increase in the supernatant levels of glycocalicin (GC, a major segment of glycoprotein Ib) in UVB-treated PCs during storage. The aim of the present study was to determine whether GC release was related to both the UV dose and the rate of dose delivery. Plateletpheresis concentrates obtained from five donors were pooled and split into five equal parts. Four of these were treated with 7500 and 15,000 mJ/cm2 UVB using two prototype UV sources with differing rates of dose delivery; namely, Baxter (BAT) and British Aerospace (BAC) cabinets, with the latter having the slower rate of delivery. On days 1 and 5 of storage, GC levels in the supernatants of PCs were determined by ELISA. Moreover, the following parameters were also assessed: platelet and WBC count; hypotonic shock response (HSR) and platelet aggregation response to ADP, ADP+collagen, ADP+arachidonic acid and ristocetin; pH; supernatant levels of lactate, glucose, von Willebrand factor (vWf) and beta-thromboglobulin (beta TG). The results revealed an association of GC release with UVB dose using both UV sources, although this was more apparent in the BAC system, in which glycocalicin release at day 5 of storage was as follows (microgram/ml, mean +/- SD): 4.8 +/- 0.3 and 9.5 +/- 3.6 at 7500 and 15,000 mJ/cm2 respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8374699

  16. EFFECT OF PLATELET RICH PLASMA CONCENTRATION ON SKELETAL MUSCLE REGENERATION: AN EXPERIMENTAL STUDY.

    PubMed

    Cianforlini, M; Mattioli-Belmonte, M; Manzotti, S; Chiurazzi, E; Piani, M; Orlando, F; Provinciali, M; Gigante, A

    2015-01-01

    Skeletal muscle injuries are common causes of severe long-term pain and physical disability, accounting for up to 55% of all sports injuries. The phases of the healing processes after direct or indirect muscle injury are complex but clearly defined and include well-coordinated steps: degeneration, inflammation, regeneration, and fibrosis. Despite this frequent occurrence and the presence of a body of data on the pathophysiology of muscle injuries, none of the current treatment strategies have shown to be really effective in strictly controlled trials. Platelet-rich plasma (PRP) is a promising alternative approach based on the ability of autologous growth factors (GFs) to accelerate tissue healing, improve muscular regeneration, increase neovascularization and reduce fibrosis. The present study is focused on the use of different concentrations of PRP as a source of GFs. Unilateral muscle lesions were created on the longissimus dorsi muscle of Wistar rats. Twenty-four h after surgical trauma, the lesion was filled with an intramuscular injection of PRP at 2 different concentrations. A group of rats were left untreated (controls). Animals were sacrificed at 3, 15 and 60 days from surgery. Histological, immunohistochemical and histomorphometric analyses were performed to evaluate muscle regeneration, neovascularization, fibrosis and inflammation. The PRP-treated muscles showed better muscle regeneration, more neovascularization and a slight reduction of fibrosis compared with the control muscles in a dose dependent manner. However, further studies also assessing pain and functional recovery are scheduled. PMID:26652490

  17. Rapid Detection of Contaminant Bacteria in Platelet Concentrate Using Differential Impedance

    PubMed Central

    Zhao, Zhihui; Chalmers, Alex; Rieder, Ronald

    2014-01-01

    BACKGROUND AND OBJECTIVES Current FDA approved culture-based methods for the bacterial testing of platelet concentrate (PC) can yield false negative results attributed to Poisson-limited sampling errors incurred near the time of collection that result in undetectable bacterial concentrations. Testing PC at the point-of-issue (POI) extends the incubation period for any contaminant bacteria increasing the probability of detection. Data are presented from time-course experiments designed to simulate POI testing of bacterially contaminated PCs at different stages of growth using differential impedance sensing. STUDY DESIGN AND METHODS Whole blood-derived PCs were typically spiked with low numbers of bacteria (~100 CFU/mL) and incubated under standard PC storage conditions. Each infected unit was evaluated every two hours over a 12- hour period. All samples were treated with a chemical compound that induces stress in the bacterial cells only. The development of any bacterial stress was monitored by detecting changes in the dielectric properties of the PC using differential impedance. RESULTS Differential impedance measurements and corresponding cell counts at the different time points are presented for six organisms implicated in post-transfusion septic reactions. All infected PCs were detected once contaminant bacteria reached concentrations ranging between 0.6 × 103 and 6 × 103 CFU/mL irrespective of the phase of growth. Results were obtained within 30 minutes after the start of the assay and without the need for cell lysis or centrifugation. CONCLUSION Differential impedance sensing can detect bacterial contamination in PC rapidly at concentrations below clinical thresholds known to cause adverse effects. PMID:24646111

  18. Comparison of humoral insulin-like growth factor-1, platelet-derived growth factor-BB, transforming growth factor-β1, and interleukin-1 receptor antagonist concentrations among equine autologous blood-derived preparations.

    PubMed

    Ionita, Christiane R; Troillet, Antonia R; Vahlenkamp, Thomas W; Winter, Karsten; Brehm, Walter; Ionita, Jean-Claude

    2016-08-01

    OBJECTIVE To compare humoral insulin-like growth factor (IGF)-1, platelet-derived growth factor (PDGF)-BB, transforming growth factor (TGF)-β1, and interleukin-1 receptor antagonist (IL-1Ra) concentrations in plasma and 3 types of equine autologous blood-derived preparations (ABPs). SAMPLE Blood and ABP samples from 12 horses. PROCEDURES Blood samples from each horse were processed by use of commercial systems to obtain plasma, platelet concentrate, conditioned serum, and aqueous platelet lysate. Half of the platelet concentrate samples were additionally treated with a detergent to release intracellular mediators. Humoral IGF-1, PDGF-BB, TGF-β1, and IL-1Ra concentrations were measured with ELISAs and compared statistically. RESULTS Median IGF-1 concentration was highest in conditioned serum and detergent-treated platelet concentrate, followed by platelet concentrate and plasma; IGF-1 was not detected in platelet lysate. Mean PDGF-BB concentration was highest in platelet lysate, followed by detergent-treated platelet concentrate and conditioned serum; PDGF-BB was not detected in plasma and platelet concentrate. Median TGF-β1 concentration was highest in detergent-treated platelet concentrate, followed by conditioned serum, platelet lysate, and platelet concentrate; TGF-β1 was not detected in most plasma samples. Median IL-1Ra concentration was highest in platelet lysate, followed by conditioned serum; IL-1Ra was not detected in almost all plasma, detergent-treated platelet concentrate, and platelet concentrate samples. CONCLUSIONS AND CLINICAL RELEVANCE Each ABP had its own cytokine profile, which was determined by the specific processing method. Coagulation and cellular lysis strongly increased humoral concentrations of cell-derived cytokines. No ABP had the highest concentrations for all cytokines. Further studies are needed to assess clinical relevance of these findings. PMID:27463555

  19. INVESTIGATION OF BIOFILM FORMATION IN COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM PLATELET CONCENTRATE BAGS.

    PubMed

    Martini, Rosiéli; Hörner, Rosmari; Rampelotto, Roberta Filipini; Garzon, Litiérri Razia Litiérri; Nunes, Melise Silveira; Teixeira, Mayza Dalcin; Graichen, Daniel Ângelo Sganzerla

    2016-01-01

    Platelet Concentrates (PCs) are the blood components with the highest rate of bacterial contamination, and coagulase-negative staphylococci (CoNS) are the most frequently isolated contaminants. This study investigated the biofilm formation of 16 contaminated units out of 691 PCs tested by phenotypic and genotypic methods. Adhesion in Borosilicate Tube (ABT) and Congo Red Agar (CRA) tests were used to assess the presence of biofilm. The presence of icaADC genes was assessed by means of the Polymerase Chain Reaction (PCR) technique. With Vitek(r)2, Staphylococcus haemolyticus was considered the most prevalent CoNS (31.25%). The CRA characterized 43.8% as probable biofilm producers, and for the ABT test, 37.5%. The icaADC genes were identified in seven samples by the PCR. The ABT technique showed 85.7% sensitivity and 100% specificity when compared to the reference method (PCR), and presented strong agreement (k = 0.8). This study shows that species identified as PCs contaminants are considered inhabitants of the normal skin flora and they might become important pathogens. The results also lead to the recommendation of ABT use in laboratory routine for detecting biofilm in CoNS contaminants of PCs. PMID:26910444

  20. INVESTIGATION OF BIOFILM FORMATION IN COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM PLATELET CONCENTRATE BAGS

    PubMed Central

    MARTINI, Rosiéli; HÖRNER, Rosmari; RAMPELOTTO, Roberta Filipini; GARZON, Litiérri Razia Litiérri; NUNES, Melise Silveira; TEIXEIRA, Mayza Dalcin; GRAICHEN, Daniel Ângelo Sganzerla

    2016-01-01

    Platelet Concentrates (PCs) are the blood components with the highest rate of bacterial contamination, and coagulase-negative staphylococci (CoNS) are the most frequently isolated contaminants. This study investigated the biofilm formation of 16 contaminated units out of 691 PCs tested by phenotypic and genotypic methods. Adhesion in Borosilicate Tube (ABT) and Congo Red Agar (CRA) tests were used to assess the presence of biofilm. The presence of icaADC genes was assessed by means of the Polymerase Chain Reaction (PCR) technique. With Vitek(r)2, Staphylococcus haemolyticus was considered the most prevalent CoNS (31.25%). The CRA characterized 43.8% as probable biofilm producers, and for the ABT test, 37.5%. The icaADC genes were identified in seven samples by the PCR. The ABT technique showed 85.7% sensitivity and 100% specificity when compared to the reference method (PCR), and presented strong agreement (k = 0.8). This study shows that species identified as PCs contaminants are considered inhabitants of the normal skin flora and they might become important pathogens. The results also lead to the recommendation of ABT use in laboratory routine for detecting biofilm in CoNS contaminants of PCs. PMID:26910444

  1. Soluble Mediators in Platelet Concentrates Modulate Dendritic Cell Inflammatory Responses in an Experimental Model of Transfusion.

    PubMed

    Perros, Alexis J; Christensen, Anne-Marie; Flower, Robert L; Dean, Melinda M

    2015-10-01

    The transfusion of platelet concentrates (PCs) is widely used to treat thrombocytopenia and severe trauma. Ex vivo storage of PCs is associated with a storage lesion characterized by partial platelet activation and the release of soluble mediators, such as soluble CD40 ligand (sCD40L), RANTES, and interleukin (IL)-8. An in vitro whole blood culture transfusion model was employed to assess whether mediators present in PC supernatants (PC-SNs) modulated dendritic cell (DC)-specific inflammatory responses (intracellular staining) and the overall inflammatory response (cytometric bead array). Lipopolysaccharide (LPS) was included in parallel cultures to model the impact of PC-SNs on cell responses following toll-like receptor-mediated pathogen recognition. The impact of both the PC dose (10%, 25%) and ex vivo storage period was investigated [day 2 (D2), day 5 (D5), day 7 (D7)]. PC-SNs alone had minimal impact on DC-specific inflammatory responses and the overall inflammatory response. However, in the presence of LPS, exposure to PC-SNs resulted in a significant dose-associated suppression of the production of DC IL-12, IL-6, IL-1α, tumor necrosis factor-α (TNF-α), and macrophage inflammatory protein (MIP)-1β and storage-associated suppression of the production of DC IL-10, TNF-α, and IL-8. For the overall inflammatory response, IL-6, TNF-α, MIP-1α, MIP-1β, and inflammatory protein (IP)-10 were significantly suppressed and IL-8, IL-10, and IL-1β significantly increased following exposure to PC-SNs in the presence of LPS. These data suggest that soluble mediators present in PCs significantly suppress DC function and modulate the overall inflammatory response, particularly in the presence of an infectious stimulus. Given the central role of DCs in the initiation and regulation of the immune response, these results suggest that modulation of the DC inflammatory profile is a probable mechanism contributing to transfusion-related complications. PMID:26133961

  2. FEASIBILITY OF RECOVERING USEFUL SALTS FROM IRRIGATION WASTEWATER CONCENTRATES PRODUCED BY POWER PLANT COOLING

    EPA Science Inventory

    The report evaluates the feasibility of a novel energy-conserving way to recover useful salts (sodium sulfate and calcium sulfate) from concentrated brines by evaporation/crystallization. The concentrated brines examined were cooling tower blowdown from agricultural wastewater an...

  3. Impact of experimental haemodilution on platelet function, thrombin generation and clot firmness: effects of different coagulation factor concentrates

    PubMed Central

    Caballo, Carolina; Escolar, Gines; Diaz-Ricart, Maribel; Lopez-Vílchez, Irene; Lozano, Miguel; Cid, Joan; Pino, Marcos; Beltrán, Joan; Basora, Misericordia; Pereira, Arturo; Galan, Ana M.

    2013-01-01

    Background Haemodilution during resuscitation after massive haemorrhage may worsen the coagulopathy and perpetuate bleeding. Materials and methods Blood samples from healthy donors were diluted (30 and-60%) using crystalloids (saline, Ringer’s lactate, PlasmalyteTM) or colloids (6% hydroxyethylstarch [HES130/0.4], 5% human albumin, and gelatin). The effects of haemodilution on platelet adhesion (Impact R), thrombin generation (TG), and thromboelastometry (TEM) parameters were analysed as were the effects of fibrinogen, prothrombin complex concentrates (PCC), activated recombinant factor VII (FVIIa), and cryoprecipates on haemodilution. Results Platelet interactions was already significantly reduced at 30% haemodilution. Platelet reactivity was not improved by addition of any of the concentrates tested. A decrease in TG and marked alterations of TEM parameters were noted at 60% haemodilution. HES130/0.4 was the expander with the most deleterious action. TG was significantly enhanced by PCC whereas rFVIIa only caused a mild acceleration of TG initiation. Fibrinogen restored the alterations of TEM parameters caused by haemodilution including those caused by HES 130/0.4. Cryoprecipitates significantly improved the alterations caused by haemodilution on TG and TEM parameters; the effects on TG disappeared after ultracentrifugation of the cryoprecipitates. Discussion The haemostatic alterations caused by haemodilution are multifactorial and affect both blood cells and coagulation. In our in vitro approach, HES 130/0.4 had the most deleterious effect on haemostasis parameters. Coagulation factor concentrates did not improve platelet interactions in the Impact R, but did have favourable effects on coagulation parameters measured by TG and TEM. Fibrinogen notably improved TEM parameters without increasing thrombin generation, suggesting that this concentrate may help to preserve blood clotting abilities during haemodilution without enhancing the prothrombotic risk. PMID

  4. Platelet rich concentrate promotes early cellular proliferation and multiple lineage differentiation of human mesenchymal stromal cells in vitro.

    PubMed

    Shani, Samuel; Ahmad, Raja Elina; Naveen, Sangeetha Vasudevaraj; Murali, Malliga Raman; Puvanan, Karunanithi; Abbas, Azlina Amir; Kamarul, Tunku

    2014-01-01

    Platelet rich concentrate (PRC) is a natural adjuvant that aids in human mesenchymal stromal cell (hMSC) proliferation in vitro; however, its role requires further exploration. This study was conducted to determine the optimal concentration of PRC required for achieving the maximal proliferation, and the need for activating the platelets to achieve this effect, and if PRC could independently induce early differentiation of hMSC. The gene expression of markers for osteocytes (ALP, RUNX2), chondrocytes (SOX9, COL2A1), and adipocytes (PPAR-γ) was determined at each time point in hMSC treated with 15% activated and nonactivated PRC since maximal proliferative effect was achieved at this concentration. The isolated PRC had approximately fourfold higher platelet count than whole blood. There was no significant difference in hMSC proliferation between the activated and nonactivated PRC. Only RUNX2 and SOX9 genes were upregulated throughout the 8 days. However, protein expression study showed formation of oil globules from day 4, significant increase in ALP at days 6 and 8 (P ≤ 0.05), and increased glycosaminoglycan levels at all time points (P < 0.05), suggesting the early differentiation of hMSC into osteogenic and adipogenic lineages. This study demonstrates that the use of PRC increased hMSC proliferation and induced early differentiation of hMSC into multiple mesenchymal lineages, without preactivation or addition of differentiation medium. PMID:25436230

  5. Autologous platelet concentrate in surgery for macular detachment associated with congenital optic disc pit

    PubMed Central

    Nadal, Jeroni; Figueroa, Marta S; Carreras, Elisa; Pujol, Patricia; Canut, Maria Isabel; Barraquer, Rafael Ignacio

    2015-01-01

    Purpose To evaluate the anatomical and functional results obtained with pars plana vitrectomy (PPV) plus autologous platelet concentrate (APC) as a treatment for macular detachment associated with optic disc pit (ODP). Methods We performed a prospective interventional study of 19 eyes of 19 consecutive patients with posterior macular detachment due to ODP. All patients underwent PPV, posterior hyaloid peeling, fluid–air exchange, injection of 0.05 mL of APC over the ODP and 15% perfluoropropane (C3F8) endotamponade. Postoperative measures included face-up positioning for 2 hours and then avoidance of the face-up position during the ensuing 10 days. All patients underwent complete ophthalmologic examination and optical coherence tomography preoperatively at 1 month, 3 months, 6 months, 9 months, and 12 months postoperatively and then annually. Outcome measures were best corrected visual acuity (BCVA) by logMAR, improvement of quality of vision, macular attachment, and resolution of intraretinal schisis-like separation. Results Preoperatively, the median BCVA was 0.70 (range: 0.30–1.70) and all patients showed improved visual acuity after surgery; BCVA was 0.22 (range: 0.07–0.52) at 12 months follow-up. All patients showed complete reabsorption of intraretinal fluid (median time: 3.5 months [range: 2–8 months]) and macular attachment at the end of follow-up (median: 60 months [range: 12–144 months]), with stable or improved visual acuity. No reoperations were needed and no major adverse events were recorded. Conclusion For macular detachment associated with ODP, the combination of PPV, posterior hyaloid peeling, APC, and C3F8 tamponade is a highly effective alternative technique with stable anatomical and functional results. PMID:26543348

  6. Equine tendonitis therapy using mesenchymal stem cells and platelet concentrates: a randomized controlled trial

    PubMed Central

    2013-01-01

    Introduction Tendon injury is a major cause of lameness and decreased performance in athletic equines. Various therapies for tendonitis have been described; however, none of these therapies results in complete tissue regeneration, and the injury recurrence rate is high even after long recovery periods involving rest and physiotherapy. Methods A lesion was induced with collagenase gel in the superficial digital flexor tendon in the center portion of the metacarpal region of eight equines of mixed breed. After two weeks, the lesions of the animals in the treated and control groups were treated through the intralesional administration of mesenchymal stem cells derived from adipose tissue (adMSCs) suspended in platelet concentrate (PC) and with phosphate buffered saline (PBS), respectively. Serial ultrasound analyses were performed every two weeks. After 16 weeks of therapy, a biopsy was performed for histopathological, immunohistochemical and gene expression (type I collagen (COL1A1), type III collagen (COL3A1), tenascin-C (TNC), tenomodulin (TNMD), and scleraxis (SCX)) analyses. Results Differences in the ultrasound and histopathological analyses were observed between the groups. Improved results were reported in the group treated with adMSCs suspended in PC. There was no difference in the gene expression levels observed after the different treatments. The main results observed from the histopathological evaluation of the treated group were as follows: a prevention of the progression of the lesion, a greater organization of collagen fibers, and a decreased inflammatory infiltrate. A lack of progression of the lesion area and its percentage was observed in the ultrasound image, and increased blood flow was measured by Power Doppler. Conclusions The use of adMSCs combined with PC for the therapy of experimentally induced tendonitis prevented the progression of the tendon lesion, as observed in the ultrasound examination, and resulted in a greater organization and

  7. Effect of platelet-rich plasma (PRP) concentration on proliferation, neurotrophic function and migration of Schwann cells in vitro.

    PubMed

    Zheng, Canbin; Zhu, Qingtang; Liu, Xiaolin; Huang, Xijun; He, Caifeng; Jiang, Li; Quan, Daping; Zhou, Xiang; Zhu, Zhaowei

    2016-05-01

    Platelet-rich plasma (PRP) contains various growth factors and appears to have the potential to promote peripheral nerve regeneration, but evidence is lacking regarding its biological effect on Schwann cells (SCs). The present study was designed to investigate the effect of PRP concentration on SCs in order to determine the plausibility of using this plasma-derived therapy for peripheral nerve injury. PRP was obtained from rats by double-step centrifugation and was characterized by determining platelet numbers and growth factor concentrations. Primary cultures of rat SCs were exposed to various concentrations of PRP (40%, 20%, 10%, 5% and 2.5%). Cell proliferation assays and flow cytometry were performed to study to assess SC proliferation. Quantitative real-time PCR and ELISA analysis were performed to determine the ability of PRP to induce SCs to produce nerve growth factor (NGF) and glial cell line-derived neurotrophic factor (GDNF). Microchemotaxis assay was used to analyse the cell migration capacity. The results obtained indicated that the platelet concentration and growth factors in our PRP preparations were significantly higher than in whole blood. Cell culture experiments showed that 2.5-20% PRP significantly stimulated SC proliferation and migration compared to untreated controls in a dose-dependent manner. In addition, the expression and secretion of NGF and GDNF were significantly increased. However, the above effects of SCs were suppressed by high PRP concentrations (40%). In conclusion, the appropriate concentration of PRP had the potency to stimulate cell proliferation, induced the synthesis of neurotrophic factors and significantly increased migration of SCs dose-dependently. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23723151

  8. 21 CFR 864.9575 - Environmental chamber for storage of platelet concentrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Environmental chamber for storage of platelet... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9575 Environmental chamber for storage of...

  9. Evaluation of Mirasol pathogen reduction system by artificially contaminating platelet concentrates with Staphylococcus epidermidis: A pilot study from India

    PubMed Central

    Chatterjee, Kabita; Zaman, Shamsuz; Chaurasia, Rahul; Singh, Surinder; Keil, Shawn D.; Tewari, Shalini; Bisht, Akanksha; Agarwal, Nitin; Rout, Diptiranjan; Chand, Subhash; Saha, Kallol

    2016-01-01

    Background and Objectives: This study was conducted to assess the efficacy of Mirasol pathogen reduction system for platelets aimed at preventing bacterial regrowth by spiking buffy coat pooled platelets (BCPP) with clinically relevant load of Staphylococous epidermidis. Materials and Methods: BCPP units were prepared using Teruflex BP-kit with Imugard III-S-PL (Terumo BCT, Tokyo, Japan). Two BCPP units were pooled, of which 40 ml of negative control (NC) was removed. The remaining volume of the platelet unit was inoculated with clinically relevant load of bacteria (total of 30 CFU of S. epidermidis in 1 ml); following this the platelet unit was split into two parts. One part served as positive control (PC) and the other part was subjected to pathogen reduction technique (Mirasol PRT, CaridianBCT Biotechnologies, Lakewood, CO, USA). Bacterial detection was performed using BacT/ALERT system, controls after day 1 and day 7 following inoculation of bacteria and on day 7 for Mirasol-treated unit. Results: Of the 32 treatment cycles, 28 were valid and 4 were invalid. No regrowth was observed in 96.4% (27 of 28) after treatment with Mirasol pathogen reduction system. Of four invalid tests, on two instances the NC showed growth, whereas in other 2 no regrowth was detected in 7th day PC. Bacterial screening of PCs by BacT/ALERT after 24 h of incubation was 28.6%, whereas the effectiveness increased to 100% when incubated for 7 days. Conclusions: Mirasol system was effective in inactivating S. epidermidis when it was deliberately inoculated into BCPP at clinically relevant concentrations. Such systems may significantly improve blood safety by inactivating traditional and emerging transfusion-transmitted pathogens.

  10. Fibrinogen concentrate as first-line therapy in aortic surgery reduces transfusion requirements in patients with platelet counts over or under 100×109/L

    PubMed Central

    Solomon, Cristina; Rahe-Meyer, Niels

    2015-01-01

    Background Administration of fibrinogen concentrate, targeting improved maximum clot firmness (MCF) of the thromboelastometric fibrin-based clot quality test (FIBTEM) is effective as first-line haemostatic therapy in aortic surgery. We performed a post-hoc analysis of data from a randomised, placebo-controlled trial of fibrinogen concentrate, to investigate whether fibrinogen concentrate reduced transfusion requirements for patients with platelet counts over or under 100×109/L. Material and methods Aortic surgery patients with coagulopathic bleeding after cardiopulmonary bypass were randomised to receive either fibrinogen concentrate (n=29) or placebo (n=32). Platelet count was measured upon removal of the aortic clamp, and coagulation and haematology parameters were measured peri-operatively. Transfusion of allogeneic blood components was recorded and compared between groups. Results After cardiopulmonary bypass, haemostatic and coagulation parameters worsened in all groups; plasma fibrinogen level (determined by the Clauss method) decreased by 43–58%, platelet count by 53–64%, FIBTEM maximum clot firmness (MCF) by 38–49%, FIBTEM maximum clot elasticity (MCE) by 43–54%, extrinsically activated test (EXTEM) MCF by 11–22%, EXTEM MCE by 25–41% and the platelet component of the clot by 23–39%. Treatment with fibrinogen concentrate (mean dose 7–9 g in the 4 groups) significantly reduced post-operative allogeneic blood component transfusion requirements when compared to placebo both for patients with a platelet count ≥100×109/L and for patients with a platelet count <100×109/L. Discussion FIBTEM-guided administration of fibrinogen concentrate reduced transfusion requirements when used as a first-line haemostatic therapy during aortic surgery in patients with platelet counts over or under 100×109/L. PMID:25369608

  11. Transfusion Efficacy of Apheresis Platelet Concentrates Irradiated at the Day of Transfusion Is Significantly Superior Compared to Platelets Irradiated in Advance

    PubMed Central

    Julmy, Friedgard; Ammann, Roland A.; Fontana, Stefano; Taleghani, Behrouz Mansouri; Hirt, Andreas; Leibundgut, Kurt

    2014-01-01

    Summary Background Gamma irradiation is currently the standard care to avoid transfusion-associated graft-versus-host disease. Guidelines on gamma irradiation of blood components state that platelets (PLTs) can be irradiated at any stage in their 5-day storage and can thereafter be stored up to their normal shelf life of 5 days after collection. In this study, we explored whether the timing of irradiation has an effect on transfusion efficacy of apheresis PLT concentrates (APCs). Methods Based on the 1-hour percent PLT recovery (PPR1h), transfusion efficacy of 1,000 eligible APCs transfused to 144 children were evaluated retrospectively. PPR1h was compared in transfused APCs irradiated at the day of transfusion and APCs irradiated in advance. Results In univariate analysis, transfusion efficacy of APCs irradiated in advance was significantly lower than that of APCs irradiated at the day of transfusion (mean PPR1h 27.7 vs. 35.0%; p = 0.007). This was confirmed in multivariate analysis (p = 0.030). Compared to non-irradiated APCs, transfusion efficacy of APCs irradiated at the day of transfusion was not significantly inferior (mean difference −2.8%; 95% CI −6.1 to 0.5%; p = 0.092), but APCs irradiated in advance were clearly less efficient (mean difference −8.1%; 95% CI −12.2 to −4.0%; p < 0.001). Conclusion Our data strongly support that APCs should not be irradiated in advance, 1.e., ≥24 h before transfusion. PMID:25053930

  12. Platelet-collagen adhesion enhances platelet aggregation induced by binding of VWF to platelets

    SciTech Connect

    Laduca, F.M.; Bell, W.R.; Bettigole, R.E. State Univ. of New York, Buffalo )

    1987-11-01

    Ristocetin-induced platelet aggregation (RIPA) was evaluated in the presence of platelet-collagen adhesion. RIPA of normal donor platelet-rich plasma (PRP) demonstrated a primary wave of aggregation mediated by the binding of von Willebrand factor (VWF) to platelets and a secondary aggregation wave, due to a platelet-release reaction, initiated by VWF-platelet binding and inhibitable by acetylsalicylic acid (ASA). An enhanced RIPA was observed in PRP samples to which collagen had been previously added. These subthreshold concentrations of collagen, which by themselves were insufficient to induce aggregation, caused measurable platelet-collagen adhesion. Subthreshold collagen did not cause microplatelet aggregation, platelet release of ({sup 3}H)serotonin, or alter the dose-responsive binding of {sup 125}I-labeled VWF to platelets, which occurred with increasing ristocetin concentrations. However, ASA inhibition of the platelet release reaction prevented collagen-enhanced RIPA. These results demonstrate that platelet-collagen adhesion altered the platelet-release reaction induced by the binding of VWF to platelets causing a platelet-release reaction at a level of VWF-platelet binding not normally initiating a secondary aggregation. These findings suggest that platelet-collagen adhesion enhances platelet function mediated by VWF.

  13. In vitro evaluation of pathogen-inactivated buffy coat-derived platelet concentrates during storage: psoralen-based photochemical treatment step-by-step

    PubMed Central

    Abonnenc, Mélanie; Sonego, Giona; Kaiser-Guignard, Julie; Crettaz, David; Prudent, Michel; Tissot, Jean-Daniel; Lion, Niels

    2015-01-01

    Background The Intercept Blood SystemTM (Cerus) is used to inactivate pathogens in platelet concentrates (PC). The aim of this study was to elucidate the extent to which the Intercept treatment modifies the functional properties of platelets. Material and methods A two-arm study was conducted initially to compare buffy coat-derived pathogen-inactivated PC to untreated PC (n=5) throughout storage. A four-arm study was then designed to evaluate the contribution of the compound adsorbing device (CAD) and ultraviolet (UV) illumination to the changes observed upon Intercept treatment. Intercept-treated PC, CAD-incubated PC, and UV-illuminated PC were compared to untreated PC (n=5). Functional characteristics were assessed using flow cytometry, hypotonic shock response (HSR), aggregation, adhesion assays and flow cytometry for the detection of CD62P, CD42b, GPIIb-IIIa, phosphatidylserine exposure and JC-1 aggregates. Results Compared to fresh platelets, end-of-storage platelets exhibited greater passive activation, disruption of the mitochondrial transmembrane potential (Δψm), and phosphatidylserine exposure accompanied by a decreased capacity to respond to agonist-induced aggregation, lower HSR, and CD42b expression. The Intercept treatment resulted in significantly lower HSR and CD42b expression compared to controls on day 7, with no significant changes in CD62P, Δψm, or phosphatidylserine exposure. GPIIbIIIa expression was significantly increased in Intercept-treated platelets throughout the storage period. The agonist-induced aggregation response was highly dependent on the type and concentration of agonist used, indicating a minor effect of the Intercept treatment. The CAD and UV steps alone had a negligible effect on platelet aggregation. Discussion The Intercept treatment moderately affects platelet function in vitro. CAD and UV illumination alone make negligible contributions to the changes in aggregation observed in Intercept-treated PC. PMID:25369598

  14. Quality of packed red blood cells and platelet concentrates collected by multicomponent collection using the MCS plus device.

    PubMed

    Leitner, G C; Jilma-Stohlawetz, P; Stiegler, G; Weigel, G; Horvath, M; Tanzmann, A; Höcker, P; Fischer, M B

    2003-01-01

    The demand for blood components is constantly increasing, while the exclusion criteria for donors are strengthened in order to reach maximal safety for donors and patients. To counterbalance reduced availability of volunteers, multicomponent collections (MCC) is an attractive approach to produce more than one component during a single apheresis procedure from one donor, such as packed red blood cells (PRBCs) and platelet concentrates (PCs). Further, the exposures of patients to a limited number of donors reduces the possibility of alloimmunization and transfusion-related diseases. We measured the quality of PRBCs and PCs obtained by MCC, using the MCS+ device with the LDPRBC program, Revision B, and compared them with the quality of manually collected PRBCs and PCs collected with the Revision C2 of the MCS+. We found higher pH levels and lower hemolysis assessed by means of fHb and K+ in the supernatant of PRBCs over the whole storage period of 42 days in MCC-derived PRBCs. The functional metabolism assessed by intracellular ATP was higher in PRBCs collected by MCC than in manually collected units. Furthermore, PCs obtained during MCC showed an increase in p-selectin expression on day 5 of storage compared to PCs collected with the Revision C2 of the MCS+. The p-selectin expression on MCC platelets was within the range of p-selectin expression found in PCs obtained by other apheresis devices. These results indicate less storage lesion in MCC-derived PRBCs compared to manually collected units and no compromise in the quality of MCC PCs obtained in the same apheresis procedure. PMID:12717789

  15. Platelet Factor 4 Inhibits and Enhances HIV-1 Infection in a Concentration-Dependent Manner by Modulating Viral Attachment.

    PubMed

    Parker, Zahra F; Rux, Ann H; Riblett, Amber M; Lee, Fang-Hua; Rauova, Lubica; Cines, Douglas B; Poncz, Mortimer; Sachais, Bruce S; Doms, Robert W

    2016-07-01

    Platelet factor 4 (PF4) has been recently shown to inhibit infection by a broad range of human immunodeficiency virus type 1 (HIV-1) isolates in vitro. We found that the inhibitory effects of PF4 are limited to a defined concentration range where PF4 exists largely in a monomeric state. Under these conditions, PF4 bound the HIV-1 envelope protein and inhibited HIV-1 attachment to the cell surface. However, as concentrations increased to the point where PF4 exists largely in tetrameric or higher-order forms, viral infection in vitro was enhanced. Enhancement could be inhibited by mutations in PF4 that shift the oligomeric equilibrium toward the monomeric state, or by using soluble glycosaminoglycans (GAGs) to which tetrameric PF4 avidly binds. We conclude that at physiologically relevant concentrations, oligomeric PF4 enhances infection by HIV-1 by interacting with the viral envelope protein as well as cell surface GAGs, enhancing virus attachment to the cell surface. This effect was not specific to HIV-1, as enhancement was seen with some but not all other viruses tested. The biphasic effects of PF4 on HIV-1 infection suggest that native PF4 will not be a useful antiviral agent and that PF4 could contribute to the hematologic abnormalities commonly seen in HIV-infected individuals by enhancing virus infection in the bone marrow. PMID:26847431

  16. Effect of autologous platelet concentrates for alveolar socket preservation: a systematic review.

    PubMed

    Moraschini, V; Barboza, E S P

    2015-05-01

    The current literature was reviewed to evaluate the effect of autologous plasma concentrates on the preservation of extraction sockets. A comprehensive literature search was performed from October 2013 to February 2014 in the MEDLINE/PubMed and Cochrane Central Register of Controlled Trials (CENTRAL) databases. Four studies, published between the years 2010 and 2013, met the eligibility criteria and were included in the review. There were 102 extractions (55 tests, 47 controls) in 82 patients. There was considerable heterogeneity between studies with regard to the design, follow-up time, surgical techniques, and method of preparation of plasma concentrates, and therefore the data could not be analyzed quantitatively. The use of plasma concentrates seems to accelerate healing and soft tissue epithelialization in extraction sockets and reduce postoperative pain and discomfort. However, there is no evidence to date to confirm that plasma concentrates improve hard tissue regeneration. PMID:25631334

  17. Platelet Interaction with Bacteria

    PubMed Central

    Clawson, C. C.

    1973-01-01

    The interaction of several common strains of bacteria with rabbit or human platelets in vitro has been examined sequentially with scanning and transmission electron microscopy. Bacteria were added to platelets in their native plasma or to washed platelets in a balanced salt solution at ratios of about 1:1 or at low bacteria to platelet ratios (down to 1:100). The platelet-bacterial interaction (PBI) was studied with recording nephelometry. Matched samples were fixed for microscopy at various points in the aggregation response. The results support these conclusions: a) Bacteria stimulate platelet aggregation by direct contact and adhesion with the platelet surface. b) Adhesion between the two cell types requires divalent cations, occurs through fusion of normal cell-surface coats and appears identical in the presence or absence of extracellular plasma protein. c) The morphologic transformation of platelets during PBI is identical to that produced by collagen. d) During PBI the bacteria are incorporated into the forming platelet aggregates and reside predominantly intercellularly. e) Phagocytosis of bacteria by a single platelet is very rare. f) Bacteria which have resided within platelet aggregates for one hour are unaltered morphologically. g) PBI occurs even at very low bacterial numbers and produces platelet-bacterial aggregates in small numbers without stimulating generalized platelet aggregation. Methods for concentration of thrombocytopenic plasma and washing human platelets are presented. ImagesFig 6Fig 7Fig 8Fig 9Fig 10Fig 11Fig 1Fig 2Fig 12Fig 13Fig 3Fig 14Fig 4Fig 5 PMID:4632008

  18. Platelet preservation: agitation and containers.

    PubMed

    van der Meer, Pieter F; de Korte, Dirk

    2011-06-01

    For platelets to maintain their in vitro quality and in vivo effectiveness, they need to be stored at room temperature with gentle agitation in gas-permeable containers. The mode of agitation affects the quality of the platelets, and a gentle method of agitation, either a circular or a flat bed movement, provides the best results. Tumblers or elliptical agitators induce platelet activation and subsequent damage. As long as the platelets remain in suspension, the agitation speed is not important. Agitation of the platelet concentrates ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. During transportation of platelet concentrates, nowadays over long distances where they are held without controlled agitation, platelets may tolerate a certain period without agitation. However, evidence is accumulating that during the time without agitation, local hypoxia surrounding the platelets may induce irreversible harm to the platelets. Over the decades, more gas-permeable plastics have been used to manufacture platelet containers. The use of different plastics and their influence on the platelet quality both in vitro and in vivo is discussed. The improved gas-permeability has allowed the extension of platelet storage from 3 days in the early 1980s, to currently at least 7 days. In the light of new developments, particularly the introduction of pathogen reduction techniques, the use of platelet additive solutions and the availability of improved automated separators, further (renewed) research in this area is warranted. PMID:21514232

  19. The effects of the oral administration of fish oil concentrate on the release and the metabolism of (/sup 14/C)arachidonic acid and (/sup 14/C)eicosapentaenoic acid by human platelets

    SciTech Connect

    Hirai, A.; Terano, T.; Hamazaki, T.; Sajiki, J.; Kondo, S.; Ozawa, A.; Fujita, T.; Miyamoto, T.; Tamura, Y.; Kumagai, A.

    1982-11-01

    It has been suggested by several investigators that eicosapentaenoic acid (C20:5 omega 3, EPA) might have anti-thrombotic effects. In this experiment, the effect of the oral administration of EPA rich fish oil concentrate on platelet aggregation and the release and the metabolism of (/sup 1 -14/C)arachidonic acid and ((U)-/sup 14/C)eicosapentaenoic acid by human platelets was studied. Eight healthy male subjects ingested 18 capsules of fish oil concentrate (EPA 1.4 g) per day for 4 weeks. Plasma and platelet concentrations of EPA markedly increased, while those of arachidonic acid (C20:4 omega 6, AA) and docosahexaenoic acid (C22:6 omega 3, DHA) did not change. Platelet aggregation induced by collagen and ADP was reduced. Collagen induced (/sup 14/C)thromboxane B2 (TXB2) formation from (/sup 14/C)AA prelabeled platelets decreased. There was no detectable formation of (/sup 14/C)TXB3 from (/sup 14/C)EPA prelabeled platelets, and the conversion of exogenous (/sup 14/C)EPA to (/sup 14/C)TXB3 was lower than that of (/sup 14/C)AA to (/sup 14/C)TXB2. The release of (/sup 14/C)AA from (/sup 14/C)AA prelabeled platelets by collagen was significantly decreased. These observations raise the possibility that the release of arachidonic acid from platelet lipids might be affected by the alteration of EPA content in platelets.

  20. Ultrasound-based Measurement of Molecular Marker Concentration in Large Blood Vessels: A Feasibility Study

    PubMed Central

    Wang, Shiying; Mauldin, F. William; Klibanov, Alexander L.; Hossack, John A.

    2014-01-01

    Ultrasound molecular imaging has demonstrated efficacy in pre-clinical studies for cancer and cardiovascular inflammation. However, these techniques often require lengthy protocols due to waiting periods or additional control microbubble injections. Moreover, they are not capable of quantifying molecular marker concentration in human tissue environments that exhibit variable attenuation and propagation path lengths. Our group recently investigated a modulated Acoustic Radiation Force (ARF)-based imaging sequence, which was demonstrated to detect targeted adhesion independent of control measurements. In the present study, this sequence was tested against various experimental parameters to determine feasibility for quantitative measurements of molecular marker concentration. Results demonstrated that measurements obtained from the sequence (residual-to-saturation ratio, Rresid) were independent of acoustic pressure and attenuation (p> 0.13, n = 10)when acoustic pressures were sufficiently low. The Rresid parameter exhibited a linear relationship with measured molecular marker concentration (R2> 0.94). Consequently, feasibility was demonstrated in vitro, for quantification of molecular marker concentration in large vessels using a modulated ARF-based sequence. Moreover, these measurements were independent of absolute acoustic reflection amplitude and used short imaging protocols(3 min) without control measurements. PMID:25308943

  1. Survival of rabbit platelets labeled with gallium 67

    SciTech Connect

    Mazoyer, E.; Carpenter, D.; Ebbe, S.; Yano, Y.; Dalal, K.; Singh, M.; Mazoyer, B.

    1988-02-01

    The viability of rabbit platelets labeled with radioactive gallium was determined to analyze the feasibility of using platelets labeled with gallium 67 as an imaging reagent for positron emission tomography. Platelets were labeled with a complex of the longer lived gallium 67 and mercaptopyridine-N-oxide (MPO) or with sodium chromate Cr 51. Their survival after transfusion was measured. Labelling efficiency of /sup 67/Ga-MPO was 6.5% to 45.8% (26.8% +/- 2.8%) when platelets were suspended in saline solution, but was much lower (1.6% +/- 0.8%) in plasma. Platelets labeled with either radioisotope in a saline medium survived as well as platelets labeled with 51Cr in plasma. Recovery values 1 hour after transfusion and mean platelet survivals were 68.6% +/- 4.9% and 3.4 +/- 0.2 days for /sup 67/Ga in saline solution, 76.5% +/- 6.8% and 3.8 +/- 0.5 days for /sup 51/Cr in saline solution, and 73.7% +/- 7.4% and 3.6 +/- 0.5 days for /sup 51/Cr in plasma. Labeled platelet concentrates always contained extra radioactivity not firmly bound to viable platelets. A postlabeling wash in saline solution did not reduce this contamination and resulted in reduction of the number of viable platelets. The results showed that rabbit platelets labeled with /sup 67/Ga-MPO survived in the circulation as well as those labeled by a standard protocol with sodium chromate Cr 51.

  2. Does Freeze-Thawing Influence the Effects of Platelet Concentrates? An In Vitro Study on Human Adipose-Derived Stem Cells.

    PubMed

    Ceci, Caterina; Niada, Stefania; Del Fabbro, Massimo; Lolato, Alessandra; Taschieri, Silvio; Giannasi, Chiara; Brini, Anna Teresa

    2016-03-01

    Human adipose-derived stem cells (hASCs) have been proposed as a possible therapy for tissue regeneration in aesthetic, plastic, and reconstructive surgery. Today, platelet concentrates are used in a wide range of disciplines, but their storage has become a controversial aspect. The purpose of this in vitro study was to evaluate the effect of plasma rich in growth factors (PRGF), after a freeze-thawing cycle, on the proliferation and biological activity of progenitor cells involved in soft tissue healing. Different formulations of activated PRGF were added to hASCs cultured in serum-free medium. Cell proliferation was assessed by MTT test and cell count up to 7 and 12-day incubation. Osteo-differentiation ability of hASCs was also tested after 7 and 14-day incubation by alkaline phosphatase assay. The effects of 4 PRGF preparations (fresh/frozen and with/without platelets) were compared with corresponding formulations of plasma poor in growth factors and with standard medium. hASCs cultured in the presence of platelet concentrates increased proliferation rate with respect to cells grown in standard medium without significant differences among all the tested plasma formulations on cell viability up to 12 days of culture. PRGF activity is preserved after cryopreservation and platelet-rich preparations promoted osteo-differentiation of hASCs at day 7. In conclusion, PRGF supports the proliferation and the differentiation of progenitor cells in vitro also when applied after cryopreservation. Platelet concentrates, either alone or in combination with mesenchymal stem cells, might be a valuable tool in the field of tissue regeneration. PMID:26872279

  3. Surgical management of macular holes: results using gas tamponade alone, or in combination with autologous platelet concentrate, or transforming growth factor β2

    PubMed Central

    Minihan, M; Goggin, M; Cleary, P

    1997-01-01

    BACKGROUND—Vitrectomy and gas tamponade has become a recognised technique for the treatment of macular holes. In an attempt to improve the anatomic and visual success of the procedure, various adjunctive therapies—cytokines, serum, and platelets—have been employed. A consecutive series of 85 eyes which underwent macular hole surgery using gas tamponade alone, or gas tamponade with either the cytokine transforming growth factor β2 (TGF-β2) or autologous platelet concentrate is reported.
METHODS—Twenty eyes had vitrectomy and 20% SF6 gas tamponade; 15 had vitrectomy, 20% SF6 gas, and TGF-β2; 50 had vitrectomy, 16% C3F8 gas tamponade, and 0.1 ml of autologous platelet concentrate prepared during the procedure.
RESULTS—Anatomic success occurred in 86% of eyes, with 96% of the platelet treated group achieving closure of the macular hole. Visual acuity improved by two lines or more in 65% of the SF6 only group, 33% of those treated with TGF-β2, and in 74% of the platelet treated group. In the platelet treated group 40% achieved 6/12 or better and 62% achieved 6/18 or better. The best visual results were obtained in stage 2 holes.
CONCLUSION—Vitrectomy for macular holes is often of benefit and patients may recover good visual acuity, especially early in the disease process. The procedure has a number of serious complications, and the postoperative posturing requirement is difficult. Patients need to be informed of such concerns before surgery.

 PMID:9497468

  4. Antiretroviral concentrations in small hair samples as a feasible marker of adherence in rural Kenya.

    PubMed

    Hickey, Matthew D; Salmen, Charles R; Tessler, Robert A; Omollo, Dan; Bacchetti, Peter; Magerenge, Richard; Mattah, Brian; Salmen, Marcus R; Zoughbie, Daniel; Fiorella, Kathryn J; Geng, Elvin; Njoroge, Betty; Jin, Chengshi; Huang, Yong; Bukusi, Elizabeth A; Cohen, Craig R; Gandhi, Monica

    2014-07-01

    Antiretroviral hair levels objectively quantify drug exposure over time and predict virologic responses. We assessed the acceptability and feasibility of collecting small hair samples in a rural Kenyan cohort. Ninety-five percentage of participants (354/373) donated hair. Although median self-reported adherence was 100% (interquartile range, 96%-100%), a wide range of hair concentrations likely indicates overestimation of self-reported adherence and the advantages of a pharmacologic adherence measure. Higher nevirapine hair concentrations observed in women and older adults require further study to unravel behavioral versus pharmacokinetic contributors. In resource-limited settings, hair antiretroviral levels may serve as a low-cost quantitative biomarker of adherence. PMID:24694932

  5. Detection of enteric viruses in activated sludge by feasible concentration methods

    PubMed Central

    Prado, Tatiana; Gaspar, Ana Maria Coimbra; Miagostovich, Marize Pereira

    2014-01-01

    Human enteric viruses are responsible to cause several diseases, including gastroenteritis and hepatitis, and can be present in high amounts in sewage sludge. This study compared virus recovery efficiency of two feasible concentration methods used for detecting human adenovirus (HAdV), rotavirus species A (RV-A), norovirus genogroup II (NoV GII) and hepatitis A virus (HAV) in sewage sludge from an activated sludge process. Twelve sewage sludge samples were collected bi-monthly from January to July, 2011. Ultracentrifugation was compared with a simplified protocol based on beef extract elution for recovering enteric viruses. Viruses were quantified by quantitative real-time PCR assays and virus recovery efficiency and limits of detection were determined. Methods showed mean recovery rates lower than 7.5%, presenting critical limits of detection (higher than 102 – 103 genome copies - GC L−1 for all viruses analyzed). Nevertheless, HAdV were detected in 90% of the analyzed sewage sludge samples (range: 1.8 × 104 to 1.1 × 105 GC L−1), followed by RV-A and NoV (both in 50%) and HAV (8%). Results suggesting that activated sludge is contaminated with high viral loads and HAdV are widely disseminated in these samples. The low virus recovery rates achieved, especially for HAV, indicate that other feasible concentration methods could be developed to improve virus recovery efficiency in these environmental matrices. PMID:24948954

  6. Parvovirus B19 Passive Transmission by Transfusion of Intercept® Blood System-Treated Platelet Concentrate

    PubMed Central

    Gowland, Peter; Fontana, Stefano; Stolz, Martin; Andina, Nicola; Niederhauser, Christoph

    2016-01-01

    Summary Background Pathogen reduction methods for blood components are effective for a large number of viruses though less against small, non-enveloped viruses such as Parvovirus B19 (B19V). This article describes the passive transmission by transfusion of two B19V-contaminated pooled platelet concentrates (PCs) which were treated with the Intercept® blood pathogen reduction system. Case Reports Two transfusion cases of B19V-contaminated Intercept-treated pooled PCs were described. Due to the analysis delay, the PCs were already transfused. The viral content of each donation was 4.87 × 1010 IU/ml in case 1and 1.46 × 108 IU/ml in case 2. B19V (52 IU/ml) was detected in the recipient of the case 1 PC, whereas no virus could be detected in the case 2 PC recipient. A B19V IgM response and a transient boost of the underlying B19V IgG immune status and was observed in recipient 1. Recipient of the case 2 PC remained B19V IgG- and IgM-negative. B19V DNA sequence and phylogenetic analysis revealed a 100% homology between donor and recipient. Conclusion This report describes passive B19V transmission by a PC with very high B19 viral load which elicited a transient boost of the B19V immunity, but not by a PC with a lower B19V content, suggesting that there is a B19 viral load threshold value at which B19V inactivation is exceeded. PMID:27403092

  7. Feasibility of using acoustic velocity meters for estimating highly organic suspended-solids concentrations in streams

    USGS Publications Warehouse

    Patino, Eduardo

    1996-01-01

    A field experiment was conducted at the Levee 4 canal site below control structure G-88 in the Everglades agricultural area in northwestern Broward County, Florida, to study the relation of acoustic attenuation to suspended-solids concentrations. Acoustic velocity meter and temperature data were obtained with concurrent water samples analyzed for suspended-solids concentrations. Two separate acoustic velocity meter frequencies were used, 200 and 500 kilohertz, to determine the sensitivity of acoustic attenuation to frequency for the measured suspended-solids concentration range. Suspended-solids concentrations for water samples collected at the Levee 4 canal site from July 1993 to September 1994 ranged from 22 to 1,058 milligrams per liter, and organic content ranged from about 30 to 93 percent. Regression analyses showed that attenuation data from the acoustic velocity meter (automatic gain control) and temperature data alone do not provide enough information to adequately describe the concentrations of suspended solids. However, if velocity is also included as one of the independent variables in the regression model, a satisfactory correlation can be obtained. Thus, it is feasible to use acoustic velocity meter instrumentation to estimate suspended-solids concentrations in streams, even when suspended solids are primarily composed of organic material. Using the most comprehensive data set available for the study (500 kiloherz data), the best fit regression model produces a standard error of 69.7 milligrams per liter, with actual errors ranging from 2 to 128 milligrams per liter. Both acoustic velocity meter transmission frequencies of 200 and 500 hilohertz produced similar results, suggesting that transducers of either frequency could be used to collect attenuation data at the study site. Results indicate that calibration will be required for each acoustic velocity meter system to the unique suspended-solids regime existing at each site. More robust solutions may

  8. Taurine and platelet aggregation

    SciTech Connect

    Nauss-Karol, C.; VanderWende, C.; Gaut, Z.N.

    1986-03-01

    Taurine is a putative neurotransmitter or neuromodulator. The endogenous taurine concentration in human platelets, determined by amino acid analysis, is 15 ..mu..M/g. In spite of this high level, taurine is actively accumulated. Uptake is saturable, Na/sup +/ and temperature dependent, and suppressed by metabolic inhibitors, structural analogues, and several classes of centrally active substances. High, medium and low affinity transport processes have been characterized, and the platelet may represent a model system for taurine transport in the CNS. When platelets were incubated with /sup 14/C-taurine for 30 minutes, then resuspended in fresh medium and reincubated for one hour, essentially all of the taurine was retained within the cells. Taurine, at concentrations ranging from 10-1000 ..mu..M, had no effect on platelet aggregation induced by ADP or epinephrine. However, taurine may have a role in platelet aggregation since 35-39% of the taurine taken up by human platelets appears to be secreted during the release reaction induced by low concentrations of either epinephrine or ADP, respectively. This release phenomenon would imply that part of the taurine taken up is stored directly in the dense bodies of the platelet.

  9. Picomolar platelet-activating factor mobilizes Ca to change platelet shape without activating phospholipase C or protein kinase C; simultaneous fluorometric measurement of intracellular free Ca concentration and aggregation.

    PubMed

    James-Kracke, M R; Sexe, R B; Shukla, S D

    1994-11-01

    The purpose of this study was to investigate signal transduction mechanisms activated by low and high concentrations of platelet-activating factor (PAF) in rabbit platelets and to contrast the responses to those induced by thrombin. We measured changes in intracellular free calcium ([Ca++]i) with fura2, while monitoring light scatter simultaneously as a measure of shape change and aggregation in a dual-excitation dual-emission spectrofluorometer. An abrupt 20% fall in light scatter, coincident with the peak of the [Ca++]i, indicated shape change in Ca-containing or Ca-free medium and was blocked by BAPTA loading and 10 microM cytochalasin B. A secondary decline in light scatter, indicating aggregation, occurred only in Ca-containing medium and only under conditions favoring protein kinase C (PKC) activation. PAF at 10(-12) M did not increase 1,4,5-inositol triphosphate content, which suggested PKC would not be activated. However, PAF at 10(-12) rapidly increased [Ca++]i to 900 nM in 7 sec seemingly by Ca influx through receptor-operated channels inducing shape change. PAF at 10(-9) and 10(-8) M increased [Ca++]i to 2 microM in 12 sec and induced both shape change and aggregation. However, in platelets pretreated with 100 nM staurosporine to inhibit protein kinases, 10(-9) M PAF did not cause aggregation even though [Ca++]i still rose to 2 microM, which indicated that PKC plays a role in aggregation but not in Ca++ mobilization.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7965802

  10. Feasibility of Uranium Concentration Measurements for H Canyon Tank 16.7

    SciTech Connect

    Lascola, R.J.

    2003-01-29

    Savannah River Technology Center (SRTC) evaluated the feasibility of using the H Canyon on-line diode array spectrophotometer to measure uranium concentrations in Tank 16.7. On-line measurements will allow an increase in highly enriched uranium (HEU) production by removing delays associated with off-line measurements. The instrument must be able to measure uranium at concentrations below 1.0 g/L with an uncertainty no greater than 0.3 g/L. SRTC determined that the system has a limit of quantitation of 0.15 g/L. At concentrations of 0.5 and 1.0 g/L, the spectrometer uncertainty is 0.10 g/L. No design changes, such as an increase in flow cell path length, are required to obtain this performance. Expected levels of iron in Tank 16.7 solutions will not interfere with the measurement. The CHEMCHEK method should not be used for confirmatory analysis, as it contributes excessively to the overall uncertainty of the measurement. SRTC expects that the spectrophotometer will meet the measurement requirements for Tank 16.7.

  11. Approaches to synthetic platelet analogs.

    PubMed

    Modery-Pawlowski, Christa L; Tian, Lewis L; Pan, Victor; McCrae, Keith R; Mitragotri, Samir; Sen Gupta, Anirban

    2013-01-01

    Platelet transfusion is routinely used for treating bleeding complications in patients with hematologic or oncologic clotting disorders, chemo/radiotherapy-induced myelosuppression, trauma and surgery. Currently, these transfusions mostly use allogeneic platelet concentrates, while products like lyophilized platelets, cold-stored platelets and infusible platelet membranes are under investigation. These natural platelet-based products pose considerable risks of contamination, resulting in short shelf-life (3-5 days). Recent advances in pathogen reduction technologies have increased shelf-life to ~7 days. Furthermore, natural platelets are short in supply and also cause several biological side effects. Hence, there is significant clinical interest in platelet-mimetic synthetic analogs that can allow long storage-life and minimum side effects. Accordingly, several designs have been studied which decorate synthetic particles with motifs that promote platelet-mimetic adhesion or aggregation. Recent refinement in this design involves combining the adhesion and aggregation functionalities on a single particle platform. Further refinement is being focused on constructing particles that also mimic natural platelet's shape, size and elasticity, to influence margination and wall-interaction. The optimum design of a synthetic platelet analog would require efficient integration of platelet's physico-mechanical properties and biological functionalities. We present a comprehensive review of these approaches and provide our opinion regarding the future directions of this research. PMID:23092864

  12. Hemostatic Function and Transfusion Efficacy of Apheresis Platelet Concentrates Treated with Gamma Irradiation in Use for Thrombocytopenic Patients

    PubMed Central

    Zhu, Mei; Xu, Wei; Wang, Bao-Long; Su, Hong

    2014-01-01

    Summary Background During the transfusion of blood components, the transfer of allogeneic donor white blood cells (WBCs) can mediate transfusion-associated graft-versus-host disease (TA-GVHD). To minimize the reaction, exposure of blood products to gamma irradiation is currently the standard of care. The aim of our study was to evaluate and compare hemostatic function, transfusion efficacy, and safety of gamma-irradiated single-donor apheresis platelet concentrates (PCs) and of conventional non-irradiated PCs in patients with chemotherapy-induced thrombocytopenia. Methods 20 double-dose single-donor leukoreduced PCs were split in two identical units; one was gamma-irradiated with 25 Gy (study arm A) and the other remains non-irradiated (study arm B). Both units were stored under equal conditions. Hematologic patients were randomly assigned to receive gamma-irradiated or conventional non-irradiated PCs. Hemostatic function was evaluated by thrombelastography (TEG). TEG measurements were taken pre transfusion and 1 and 24 h post transfusion. TEG profiles were measured, noting the time to initiate clotting (R), the angle of clot formation (α), and the maximum amplitude (clot strength (MA)). Whole blood samples were collected from these thrombocytopenic patients at 1 and 24 h for PLT count increments (CIs) and corrected count increments (CCIs) with assessments of transfusion efficacy. Time to next PLT transfusion, transfusion requirement of RBCs, active bleeding, and adverse events (AEs), were analyzed. Results No differences could be found in hemostatic function parameters (MA, R, and α) between study arms A and B (all p values > 0.096) pre transfusion as well as 1 and 24 h post transfusion. No differences between study arms A and B were observed for mean (± standard deviation (SD)) 1-hour CCI (12.83 ± 6.33 vs. 11.59 ± 5.97) and 24-hour CCI (6.56 ± 4.10 vs. 5.76 ± 4.05). Mean 1-hour CI and 24-hour CI were not significantly different in both study arms (p = 0

  13. Inhibitory Effects of Cytosolic Ca2+ Concentration by Ginsenoside Ro Are Dependent on Phosphorylation of IP3RI and Dephosphorylation of ERK in Human Platelets

    PubMed Central

    Kwon, Hyuk-Woo; Shin, Jung-Hae; Lee, Dong-Ha; Park, Hwa-Jin

    2015-01-01

    Intracellular Ca2+ ([Ca2+]i) is platelet aggregation-inducing molecule and is involved in activation of aggregation associated molecules. This study was carried out to understand the Ca2+-antagonistic effect of ginsenoside Ro (G-Ro), an oleanane-type saponin in Panax ginseng. G-Ro, without affecting leakage of lactate dehydrogenase, dose-dependently inhibited thrombin-induced platelet aggregation, and the half maximal inhibitory concentration was approximately 155 μM. G-Ro inhibited strongly thrombin-elevated [Ca2+]i, which was strongly increased by A-kinase inhibitor Rp-8-Br-cAMPS compared to G-kinase inhibitor Rp-8-Br-cGMPS. G-Ro increased the level of cAMP and subsequently elevated the phosphorylation of inositol 1, 4, 5-triphosphate receptor I (IP3RI) (Ser1756) to inhibit [Ca2+]i mobilization in thrombin-induced platelet aggregation. Phosphorylation of IP3RI (Ser1756) by G-Ro was decreased by PKA inhibitor Rp-8-Br-cAMPS. In addition, G-Ro inhibited thrombin-induced phosphorylation of ERK 2 (42 kDa), indicating inhibition of Ca2+ influx across plasma membrane. We demonstrate that G-Ro upregulates cAMP-dependent IP3RI (Ser1756) phosphorylation and downregulates phosphorylation of ERK 2 (42 kDa) to decrease thrombin-elevated [Ca2+]i, which contributes to inhibition of ATP and serotonin release, and p-selectin expression. These results indicate that G-Ro in Panax ginseng is a beneficial novel Ca2+-antagonistic compound and may prevent platelet aggregation-mediated thrombotic disease. PMID:26355658

  14. Inhibitory Effects of Cytosolic Ca(2+) Concentration by Ginsenoside Ro Are Dependent on Phosphorylation of IP3RI and Dephosphorylation of ERK in Human Platelets.

    PubMed

    Kwon, Hyuk-Woo; Shin, Jung-Hae; Lee, Dong-Ha; Park, Hwa-Jin

    2015-01-01

    Intracellular Ca(2+) ([Ca(2+)] i ) is platelet aggregation-inducing molecule and is involved in activation of aggregation associated molecules. This study was carried out to understand the Ca(2+)-antagonistic effect of ginsenoside Ro (G-Ro), an oleanane-type saponin in Panax ginseng. G-Ro, without affecting leakage of lactate dehydrogenase, dose-dependently inhibited thrombin-induced platelet aggregation, and the half maximal inhibitory concentration was approximately 155 μM. G-Ro inhibited strongly thrombin-elevated [Ca(2+)] i , which was strongly increased by A-kinase inhibitor Rp-8-Br-cAMPS compared to G-kinase inhibitor Rp-8-Br-cGMPS. G-Ro increased the level of cAMP and subsequently elevated the phosphorylation of inositol 1, 4, 5-triphosphate receptor I (IP3RI) (Ser(1756)) to inhibit [Ca(2+)] i mobilization in thrombin-induced platelet aggregation. Phosphorylation of IP3RI (Ser(1756)) by G-Ro was decreased by PKA inhibitor Rp-8-Br-cAMPS. In addition, G-Ro inhibited thrombin-induced phosphorylation of ERK 2 (42 kDa), indicating inhibition of Ca(2+) influx across plasma membrane. We demonstrate that G-Ro upregulates cAMP-dependent IP3RI (Ser(1756)) phosphorylation and downregulates phosphorylation of ERK 2 (42 kDa) to decrease thrombin-elevated [Ca(2+)] i , which contributes to inhibition of ATP and serotonin release, and p-selectin expression. These results indicate that G-Ro in Panax ginseng is a beneficial novel Ca(2+)-antagonistic compound and may prevent platelet aggregation-mediated thrombotic disease. PMID:26355658

  15. Feasibility of hydroxyl concentration measurements by laser-saturated fluorescence in high-pressure flames.

    PubMed

    Carter, C D; Salmon, J T; King, G B; Laurendeau, N M

    1987-11-01

    A feasibility study has been performed on the application of laser-saturated fluoresence (LSF) to the measurement of OH concentration in high-pressure flames. Using a numerical model for the collisional dynamics of the OH molecule under nonuniform laser excitation, we have investigated the effect of pressure on the balanced cross-rate model and determined the sensitivity of the depopulation of the laser-coupled levels to the ratio of rate coefficients describing (1) electronic quenching of the vibrational levels for which upsilon'' > 0 and (2) vibrational relaxation from upsilon'' > 0 to upsilon'' = 0. At sufficiently high pressures in near-saturated conditions, the total population of the laser-coupled levels reaches an asymptotic value, which is insensitive to the degree of saturation. When the ratio of electronic quenching is vibrational relaxation is small and the rate coefficients for rotational transfer in the ground and excited electronic states are nearly the same, the balanced cross-rate model remains a good approximation for all pressures. When the above ratio is large, depopulation of the laser-coupled levels becomes significant at high pressures, and thus the balanced crossrate model no longer holds. In these conditions, however, knowledge of the asymptotic value achieved by the laser-coupled levels could be used to correct the balanced cross-rate model and thus allow LSF measurements at sufficiently high pressures. PMID:20523402

  16. Feasibility of the Simultaneous Determination of Monomer Concentrations and Particle Size in Emulsion Polymerization Using in Situ Raman Spectroscopy

    PubMed Central

    2015-01-01

    An immersion Raman probe was used in emulsion copolymerization reactions to measure monomer concentrations and particle sizes. Quantitative determination of monomer concentrations is feasible in two-monomer copolymerizations, but only the overall conversion could be measured by Raman spectroscopy in a four-monomer copolymerization. The feasibility of measuring monomer conversion and particle size was established using partial least-squares (PLS) calibration models. A simplified theoretical framework for the measurement of particle sizes based on photon scattering is presented, based on the elastic-sphere-vibration and surface-tension models. PMID:26900256

  17. Vascular endothelial growth factor concentrations in the plasma-activated platelets rich (P-APR) of healthy controls and colorectal cancer patients.

    PubMed

    Ranieri, Girolamo; Coviello, Maria; Patruno, Rosa; Valerio, Paolo; Martino, Domenico; Milella, Pietro; Catalano, Vittorio; Scotto, Francesco; De Ceglie, Antonella; Quaranta, Michele; Ribatti, Domenico; Pellecchia, Antonio

    2004-10-01

    Vascular endothelial growth factor (VEGF) is known to play a key role in tumour angiogenesis. Our preliminary published data suggest that plasma-activated platelets rich (P-APR) rather than other plasma compartments (i.e. plasma, plasma-platelets poor) or serum is the more suitable blood fraction for measuring VEGF in a miscellaneous series of gastrointestinal cancer patients. The aim of this confirmatory study was to assess VEGF in P-APR blood compartments of 30 healthy control subjects (HCS) and a homogeneous series of 62 colorectal cancer patients (CRCP), prospectively collected, to evaluate its possible clinical-biological significance. Samples of plasma (P) in both sodium citrate (SC) and sodium citrate-theophylline-adenosine-dipyridamole (CTAD) were collected from venous blood. After the centrifugation and separation methods VEGF levels were detected by ELISA in P-APR. The best differentiation between HCS and CRCP in VEGF level was seen for P-APRCTAD (median value: 255 pg/ml versus 142 pg/ml; p=0.000 by Mann-Whitney U test). No significant correlation among the P-APR VEGF concentrations and the main clinical pathological features was found. We suggest that P-APRCTAD fraction, obtained according to well standardised conditions, could represent the suitable blood compartment for the assessment of VEGF as marker of malignant intestinal transformation. PMID:15375505

  18. 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.

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

    PubMed

    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. PMID:2633402

  20. 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

  1. Covalent co-immobilization of heparin/laminin complex that with different concentration ratio on titanium surface for selectively direction of platelets and vascular cells behavior

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Chen, Yuan; Liu, Tao; Wang, Xue; Liu, Yang; Wang, Yuan; Chen, Junying; Huang, Nan

    2014-10-01

    Surface biofunctional modification of coronary artery stent to improve the hemocompatibility and selectively accelerate endothelium regeneration but prevent restenosis have been become a new hotspot. For this, a novel method was developed in this work by co-immobilization of Ln and heparin complex on poly-L-lysine modified Ti surface. Take the advantage of the specific interaction between Ln and heparin, Ln and heparin complexes with different concentration ratios were set up for creating different exposure density of these two types of biomolecules. According to biocompatibility evaluation results, the Hep/Ln complexes modified surface displayed less platelet adhesion and activation. Especially, on L(150)H and L(200)H surface, the AT III binding quantity, APTT value and anti-coagulation property of modified surface were significantly promoted. Furthermore, the adherent density and proliferation activity of ECs and EPCs were positively correlated with Ln concentration. Notably, the proliferation of both ECs and EPCs on L(100)H, L(150)H and L(200)H surface were greatly promoted. Another hand, the proliferation activity of SMCs was significantly inhibited on Hep/Ln modified surfaces, which was considered mainly due to the inhibitory effect of heparin to SMCs. According to the existing results, this study demonstrated that in a certain range of heparin and laminin concentration ratio, the biological behavior of platelets, ECs, EPCs and SMCs could be selectively directed. We suggested that this article provided a potential method to construct an adequate platform on a stent surface for accelerate endothelialization with low side effects.

  2. PLATELET FORMATION

    PubMed Central

    Thon, Jonathan N.; Italiano, Joseph E.

    2010-01-01

    Thrombocytopenia is the underlying cause of a number of major clinical conditions and genetic disorders worldwide. While therapeutic agents that bind and stimulate the thrombopoietin receptor are currently available, the development of drugs that directly stimulate megakaryocytes to generate platelets has lagged behind. To improve the management of thrombocytopenia, we will need to define the cell biological pathways that drive the production of platelets from megakaryocytes. This review integrates the latest research of platelet biogenesis and focuses on the molecular pathways that power and regulate proplatelet production. PMID:20620432

  3. Donor selection criteria to maximize double platelet products (DPP) by platelet apheresis.

    PubMed

    Wollersheim, Jacques; Dautzenberg, Maaike; van de Griendt, Astrid; Sybesma, Bob

    2006-04-01

    Variant Creutzfeldt-Jakob disease brought us to perform a study to diminish donor exposure from transfusion of platelet concentrates. The current study aimed to develop donor selection criteria that maximize the likelihood of deriving single donor platelets and producing double platelet products (DPP). Donors were recruited among plasmapheresis donors and among other donors when the selected donors did not show up. Donor precount and body weight and haematocrit were examined as determinants of higher split-rates combined with procedure time. When the criterion was set on 225; 82% of the procedures (n=717) with a precount of >225 yielded DPP compared to 54% of the procedures with a precount <225 (p<.01). Body weight >65 kg gave good results in split-rate. Procedure time showed an inverse correlation with the highest correlating precount (r=-.14; p<.001). Eighty one percent of the donors reported a willingness to donate at least seven times a year and 75% accepted the mean procedure time. This confirmed logistical feasibility of the conversion to AP-PC although profits would be reduce 13% compared to platelets from pooled buffy coats. PMID:16574489

  4. Biologic nanoparticles and platelet reactivity

    PubMed Central

    Miller, Virginia M; Hunter, Larry W; Chu, Kevin; Kaul, Vivasvat; Squillace, Phillip D; Lieske, John C; Jayachandran, Muthuvel

    2009-01-01

    Aim Nanosized particles (NPs) enriched in hydroxyapatite and protein isolated from calcified human tissue accelerate occlusion of endothelium-denuded arteries when injected intravenously into rabbits. Since platelet aggregation and secretory processes participate in normal hemostasis, thrombosis and vascular remodeling, experiments were designed to determine if these biologic NPs alter specific platelet functions in vitro. Methods Platelet-rich plasma was prepared from citrate anticoagulated human blood. Platelet aggregation and ATP secretion were monitored in response to thrombin receptor agonists peptide (10 μM) or convulxin (50 μg/ml) prior to and following 15 min incubation with either control solution, human-derived NPs, bovine-derived NPs or crystals of hydroxyapatite at concentrations of 50 and 150 nephelometric turbidity units. Results Incubation of platelets for 15 min with either human- or bovine-derived NPs reduced aggregation induced by thrombin receptor activator peptide and convulxin in a concentration-dependent manner. Hydroxyapatite caused a greater inhibition than either of the biologically derived NPs. Human-derived NPs increased ATP secretion by unstimulated platelets during the 15 min incubation period. Conclusion Effects of bovine-derived and hydroxyapatite NPs on basal release of ATP were both time and concentration dependent. These results suggest that biologic NPs modulate both platelet aggregation and secretion. Biologically derived NPs could modify platelet responses within the vasculature, thereby reducing blood coagulability and the vascular response to injury. PMID:19839809

  5. Higher body weight patients on clopidogrel maintenance therapy have lower active metabolite concentrations, lower levels of platelet inhibition, and higher rates of poor responders than low body weight patients.

    PubMed

    Wagner, Henrik; Angiolillo, Dominick J; Ten Berg, Jurrien M; Bergmeijer, Thomas O; Jakubowski, Joseph A; Small, David S; Moser, Brian A; Zhou, Chunmei; Brown, Patricia; James, Stefan; Winters, Kenneth J; Erlinge, David

    2014-01-01

    Body weight is a predictor of clopidogrel response. However, no prospective studies have compared pharmacodynamic (PD) and pharmacokinetic (PK) data based on body weight. We compared PD and PK effects of clopidogrel 75 mg in low body weight (LBW, <60 kg) and higher body weight (HBW, ≥60 kg) patients with stable coronary artery disease. LBW (n = 34, 56.4 ± 3.7 kg) and HBW (n = 38, 84.7 ± 14.9 kg) aspirin-treated patients received clopidogrel 75 mg for 10-14 days. The area under the concentration-time curve of active metabolite (Clop-AM) calculated through the last quantifiable concentration up to 4 h postdose, AUC(0-tlast), was calculated by noncompartmental methods. Light transmission aggregometry (LTA) (maximum platelet aggregation and inhibition of platelet aggregation to 20 μM adenosine diphosphate (ADP), and residual platelet aggregation to 5 μM ADP), VerifyNow(®) P2Y12 reaction units (PRU), and vasodilator-associated stimulated phosphoprotein phosphorylation platelet reactivity index (VASP-PRI) were performed. Mean AUC(0-tlast) was lower in HBW than LBW patients: 12.8 versus 17.9 ng h/mL. HBW patients had higher platelet reactivity as measured by LTA (all p ≤ 0.01), PRU (207 ± 68 vs. 152 ± 57, p < 0.001), and VASP-PRI (56 ± 18 vs. 39 ± 17, p < 0.001). More HBW patients exhibited high on-treatment platelet reactivity (HPR) using PRU (35 vs. 9%) and VASP-PRI (65 vs. 27%). Body weight correlated with PRU and VASP-PRI (both p < 0.001), and inversely with log transformed AUC(0-tlast) (p < 0.001). In conclusion, HBW patients had lower levels of Clop-AM, and higher platelet reactivity and rates of HPR than LBW subjects, contributing to their suboptimal response to clopidogrel. PMID:24043374

  6. Platelet count

    MedlinePlus

    ... reactions Cancer Certain medicines Bone marrow disease called polycythemia vera Bone marrow making too many platelets without a ... leukemia (CML) Hemolytic anemia Idiopathic thrombocytopenic purpura (ITP) Polycythemia vera Thrombocytopenia Patient Instructions Deep vein thrombosis - discharge Update ...

  7. Platelet Count

    MedlinePlus

    ... rash Small purplish spots on the skin called purpura, caused by bleeding under the skin Testing may ... Idiopathic thrombocytopenia (ITP), also known as immune thrombocytopenic purpura, is the result of antibody production against platelets. ...

  8. Haemostasis monitored in stored red blood cells, plasma and platelet concentrates in the proportion of 4 :  4 :  1 diluted with crystalloids and colloids.

    PubMed

    Ågren, Anna; Edgren, Gustaf; Ambrosio, Daniela; Gryfelt, Gunilla; Östlund, Anders; Wikman, Agneta

    2016-04-01

    The aim of this in-vitro study was to evaluate haemostasis analysed with thromboelastometry and blood gas and blood count variables, in stored blood components and the effects after dilution with Ringer[Combining Acute Accent]s acetate, albumin and hydroxyethyl starch (HES). Aliquots from stored red blood cells, plasma and platelet concentrates were mixed in the proportion of 4 : 4 : 1 and analysed with rotational thromboelastometry (ROTEM), blood count [haemoglobin (Hb), haematocrit, platelet count] and blood gas (pH, calcium, sodium, potassium, glucose levels). The blood mix was thereafter diluted 20 and 33% with Ringer's acetate, albumin or HES. The stored blood component mix in a ratio of 4 : 4 : 1 had a low pH (7.11 ± 0.03, mean ± standard deviation), nonmeasurable calcium level, and high concentrations of sodium, potassium and glucose but ROTEM curves within normal range after recalcification. With Ringer's acetate dilution, the ROTEM variables changed almost linearly with increasing dilution volume. When albumin was used in the 33% dilution, the clot firmness of the fibrin clot (FibTEM) was further reduced, and with HES dilution, there was a pronounced impairment. The stored blood mix had a low pH and calcium level, both of which might have a significant influence on the coagulation process but normal ROTEM curves after recalcification. Dilution with Ringer's acetate and albumin resulted in moderate deterioration, while dilution with HES showed severely impaired haemostasis. PMID:26963027

  9. 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.

  10. Bench Test for the Detection of Bacterial Contamination in Platelet Concentrates Using Rapid and Cultural Detection Methods with a Standardized Proficiency Panel

    PubMed Central

    Vollmer, Tanja; Knabbe, Cornelius; Geilenkeuser, Wolf-Jochen; Schmidt, Michael; Dreier, Jens

    2015-01-01

    Summary Background The most frequent infectious complication in transfusion therapy in developed countries is related to the bacterial contamination of platelet concentrates (PCs). Rapid and cultural screening methods for bacterial detection in platelets are available, but external performance evaluation, especially of rapid methods, has been difficult to realize so far. Here we summarize the results of three individual collaborative trials using an external quality assessment program (EQAP) for the application of current rapid and cultural screening methods. Methods Three different modules were available for the detection of bacterial contamination: module 1: rapid methods, module 2: culture methods, module 3: bacterial identification methods. The sample set-up included up to six different bacterial strains, 1-2 negative samples and 4-6 positive samples with stabilized bacterial cell counts (approximately 103/104/105 CFU/ml). Time schedule for testing was limited (module 1: 6 h, module 2 and 3: 7 days). Results Samples of module 1 were analyzed with two different rapid methods (BactiFlow, NAT). The results of the three individual collaborative trials showed that all participants detected the negative samples with both assays correctly. Samples spiked with 104 to 105 CFU/ml of bacteria obtained positive results with both rapid screening methods, whereas samples spiked with only 103 CFU/ml disclosed a lower number of correctly identified positive results by NAT (86.6-93.8% sensitivity) compared to BactiFlow (100% sensitivity). The results for modules 2 and 3 revealed a 100% diagnostic sensitivity and specificity in all three collaborative trials. Conclusion This proficiency panel facilitates the verification of the analytical sensitivity of rapid and cultural bacterial detection systems under controlled routine conditions. The concept of samples provided in this EQAP has three main advantages: i) samples can be examined by both rapid and culture methods, ii) the

  11. 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 ...

  12. Feasibility Studies on Pipeline Disposal of Concentrated Copper Tailings Slurry for Waste Minimization

    NASA Astrophysics Data System (ADS)

    Senapati, Pradipta Kumar; Mishra, Barada Kanta

    2016-06-01

    The conventional lean phase copper tailings slurry disposal systems create pollution all around the disposal area through seepage and flooding of waste slurry water. In order to reduce water consumption and minimize pollution, the pipeline disposal of these waste slurries at high solids concentrations may be considered as a viable option. The paper presents the rheological and pipeline flow characteristics of copper tailings samples in the solids concentration range of 65-72 % by weight. The tailings slurry indicated non-Newtonian behaviour at these solids concentrations and the rheological data were best fitted by Bingham plastic model. The influence of solids concentration on yield stress and plastic viscosity for the copper tailings samples were discussed. Using a high concentration test loop, pipeline experiments were conducted in a 50 mm nominal bore (NB) pipe by varying the pipe flow velocity from 1.5 to 3.5 m/s. A non-Newtonian Bingham plastic pressure drop model predicted the experimental data reasonably well for the concentrated tailings slurry. The pressure drop model was used for higher size pipes and the operating conditions for pipeline disposal of concentrated copper tailings slurry in a 200 mm NB pipe with respect to specific power consumption were discussed.

  13. Numerical simulation of platelet margination in microcirculation

    NASA Astrophysics Data System (ADS)

    Zhao, Hong; Shaqfeh, Eric

    2009-11-01

    The adhesion of platelets to vascular walls is the first step in clotting. This process critically depends on the preferential concentration of platelets near walls. The presence of red blood cells, which are the predominant blood constituents, is known to affect the steady state platelet concentration and the dynamic platelet margination, but the underlying mechanism is not well understood to-day. We use a direct numerical simulation to study the platelet margination process, with particular emphasis on the Stokesian hydrodynamic interactions among red cells, platelets, and vessel walls. Well-known mechanical models are used for the shearing and bending stiffness of red cell membranes, and the stiffer platelets are modeled as rigid discoids. A boundary integral formulation is used to solve the flow field, where the numerical solution procedure is accelerated by a parallel O(N N) smooth particle-mesh Ewald method. The effects of red cell hematocrit and deformability will be discussed.

  14. The feasibility of concentrated rural settlement in a context of post-disaster reconstruction: a study of China.

    PubMed

    Peng, Yi; Shen, Liyin; Zhang, Xiaoling; Ochoa, J Jorge

    2014-01-01

    There is growing appreciation of the use of concentrated rural settlement as an effective means of implementing infrastructure projects and helping to achieve sustainable development in rural areas. This occurs in China through the exchange of rural residential land for urban construction. However, this policy has not been effective under normal circumstances (called development-driven conditions) as frequently farmers are reluctant to accept such an exchange. By contrast, in a time of disaster, such as after the 2008 earthquake in Sichuan Province, China, rural victims have accepted this policy of rural residential land exchange. Employing game theory, this paper identifies the reasons for the different outcomes and it contends that the implementation of concentrated rural settlement practice under disaster-induced conditions is more effective than its introduction under development-driven conditions. The results of the analysis indicate that, in China, concentrated rural settlement is feasible in a context of post-disaster reconstruction. PMID:24325241

  15. Simple tube centrifugation for processing platelet-rich plasma in the horse

    PubMed Central

    Fontenot, Robin L.; Sink, Carolyn A.; Werre, Stephen R.; Weinstein, Nicole M.; Dahlgren, Linda A.

    2012-01-01

    This study evaluated the quality and bacteriologic safety of platelet-rich plasma (PRP) produced by 3 simple, inexpensive tube centrifugation methods and a commercial system. Citrated equine blood collected from 26 normal horses was processed by 4 methods: blood collection tubes centrifuged at 1200 and 2000 × g, 50-mL conical tube, and a commercial system. White blood cell (WBC), red blood cell (RBC), and platelet counts and mean platelet volume (MPV) were determined for whole blood and PRP, and aerobic and anaerobic cultures were performed. Mean platelet concentrations ranged from 1.55- to 2.58-fold. The conical method yielded the most samples with platelet concentrations greater than 2.5-fold and within the clinically acceptable range of > 250 000 platelets/λL. White blood cell counts were lowest with the commercial system and unacceptably high with the blood collection tubes. The conical tube method may offer an economically feasible and comparatively safe alternative to commercial PRP production systems. PMID:23729823

  16. Influence of irradiation on stored platelets

    SciTech Connect

    Moroff, G.; George, V.M.; Siegl, A.M.; Luban, N.L.

    1986-09-01

    Platelet concentrates intended for transfusion to immunosuppressed patients are irradiated to minimize transfusion-induced graft-versus-host disease. Because few reports describe how irradiation influences stored platelets, the authors studied whether 5000 rad of gamma irradiation, the maximum dose currently used clinically, altered platelets in vitro. Platelet concentrates were stored for either 1 day or 5 days in plastic (PL 732) containers before gamma irradiation. One unit of a pair of identical platelet concentrates was irradiated; the second unit served as a control. Irradiation did not alter platelet morphology, mean platelet volume, expression of platelet-factor-3 activity, response to hypotonic stress, extent of discharge of lactate dehydrogenase, release of beta-thromboglobulin, formation of thromboxane B2, nor the ability to undergo synergistic aggregation. The lack of any substantial change was observed whether the platelet concentrates were stored initially for either 1 day or 5 days. These results suggest that stored platelets are not altered deleteriously by irradiation with 5000 rad.

  17. Feasibility of field portable near infrared (NIR) spectroscopy to determine cyanide concentrations in soil

    NASA Astrophysics Data System (ADS)

    Sut, Magdalena; Fischer, Thomas; Repmann, Frank; Raab, Thomas

    2013-04-01

    In Germany, at more than 1000 sites, soil is polluted with an anthropogenic contaminant in form of iron-cyanide complexes. These contaminations are caused by former Manufactured Gas Plants (MGPs), where electricity for lighting was produced in the process of coal gasification. The production of manufactured gas was restrained in 1950, which caused cessation of MGPs. Our study describes the application of Polychromix Handheld Field Portable Near-Infrared (NIR) Analyzer to predict the cyanide concentrations in soil. In recent times, when the soil remediation is of major importance, there is a need to develop rapid and non-destructive methods for contaminant determination in the field. In situ analysis enables determination of 'hot spots', is cheap and time saving in comparison to laboratory methods. This paper presents a novel usage of NIR spectroscopy, where a calibration model was developed, using multivariate calibration algorithms, in order to determine NIR spectral response to the cyanide concentration in soil samples. As a control, the contaminant concentration was determined using conventional Flow Injection Analysis (FIA). The experiments revealed that portable near-infrared spectrometers could be a reliable device for identification of contamination 'hot spots', where cyanide concentration are higher than 2400 mg kg-1 in the field and >1750 mg kg-1 after sample preparation in the laboratory, but cannot replace traditional laboratory analyses due to high limits of detection.

  18. Nowcasting and Forecasting Concentrations of Biological Contaminants at Beaches: A Feasibility and Case Study

    EPA Science Inventory

    Public concern over microbial contamination of recreational waters has increased in recent years. A common approach to evaluating beach water quality has been to use the persistence model which assumes that day-old monitoring results provide accurate estimates of current concentr...

  19. Economic feasibility of segregating dark northern spring wheat by protein concentration during harvest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In-line, optical sensing has been developed for on-combine measurement and mapping of grain protein concentration (GPC). The objective of this study was to estimate changes in costs and net returns from using this technology for segregation of the dark northern spring (DNS) subclass of hard red whe...

  20. Feasibility of Estimating Constituent Concentrations and Loads Based on Data Recorded by Acoustic Instrumentation

    USGS Publications Warehouse

    Lietz, A.C.

    2002-01-01

    The acoustic Doppler current profiler (ADCP) and acoustic Doppler velocity meter (ADVM) were used to estimate constituent concentrations and loads at a sampling site along the Hendry-Collier County boundary in southwestern Florida. The sampling site is strategically placed within a highly managed canal system that exhibits low and rapidly changing water conditions. With the ADCP and ADVM, flow can be gaged more accurately rather than by conventional field-data collection methods. An ADVM velocity rating relates measured velocity determined by the ADCP (dependent variable) with the ADVM velocity (independent variable) by means of regression analysis techniques. The coefficient of determination (R2) for this rating is 0.99 at the sampling site. Concentrations and loads of total phosphorus, total Kjeldahl nitrogen, and total nitrogen (dependent variables) were related to instantaneous discharge, acoustic backscatter, stage, or water temperature (independent variables) recorded at the time of sampling. Only positive discharges were used for this analysis. Discharges less than 100 cubic feet per second generally are considered inaccurate (probably as a result of acoustic ray bending and vertical temperature gradients in the water column). Of the concentration models, only total phosphorus was statistically significant at the 95-percent confidence level (p-value less than 0.05). Total phosphorus had an adjusted R2 of 0.93, indicating most of the variation in the concentration can be explained by the discharge. All of the load models for total phosphorus, total Kjeldahl nitrogen, and total nitrogen were statistically significant. Most of the variation in load can be explained by the discharge as reflected in the adjusted R2 for total phosphorus (0.98), total Kjeldahl nitrogen (0.99), and total nitrogen (0.99).

  1. Feasibility of hydroxyl concentration measurements by laser-saturated fluorescence in high-pressure flames

    NASA Technical Reports Server (NTRS)

    Carter, Campbell D.; King, Galen B.; Laurendeau, Normand M.; Salmon, J. Thaddeus

    1987-01-01

    The effect of pressure on the laser-saturated fluorescence method for measuring OH concentration in high-pressure flames is studied using calculations for the burned-gas region of a stoichiometric H2-O2 flame at 2000 K. A numerical model of the excitation dynamics of OH is developed to explore the validity of the balanced cross-rate model at higher pressures. It is shown that depopulation of the laser-coupled levels is sensitive to collisions which depopulate v-double-prime (VDP) = 0 and to rate coefficients for rotational transfer in the ground state which are smaller than those in the excited state. In particular, it is shown that the depopulation of VDP = 0, and hence the laser-coupled levels, depends on the probability of electronic quenching to vibrational levels for which VDP is greater than 0 and vibrational relaxation to VDP = 0.

  2. High glucose concentration induces the overexpression of transforming growth factor-beta through the activation of a platelet-derived growth factor loop in human mesangial cells.

    PubMed Central

    Di Paolo, S.; Gesualdo, L.; Ranieri, E.; Grandaliano, G.; Schena, F. P.

    1996-01-01

    High glucose concentration has been shown to induce the overexpression of transforming growth factor (TGF)-beta 1 mRNA and protein in different cell types, including murine mesangial cells, thus possibly accounting for the expansion of mesangial extracellular matrix observed in diabetic glomerulopathy. In the present study, we evaluated platelet-derived growth factor (PDGF) B-chain and PDGF-beta receptor gene expression in human mesangial cells (HMCs) exposed to different concentrations of glucose and then sought a possible relationship between a PDGF loop and the modulation of TGF-beta 1 expression. HMC [3H]thymidine incorporation was upregulated by 30 mmol/L glucose (HG) up to 24 hours, whereas it was significantly inhibited at later time points. Neutralizing antibodies to PDGF BB abolished the biphasic response to HG, whereas anti-TGF-beta antibodies reversed only the late inhibitory effect of hyperglycemic medium. HG induced an early and persistent increase of PDGF B-chain gene expression, as evaluated by reverse transcriptase polymerase chain reaction, whereas PDGF-beta receptor mRNA increased by twofold after 6 hours, thereafter declining at levels 70% lower than in controls after 24 hours. 125I-Labeled PDGF BB binding studies in HMCs exposed to HG for 24 hours confirmed the decrease of PDGF-beta receptor expression. TGF-beta 1-specific transcripts showed 43 and 78% increases after 24 and 48 hours of incubation in HG, respectively, which was markedly diminished by anti-PDGF BB neutralizing antibodies or suramin. We conclude that HG induces an early activation of a PDGF loop that, in turn, causes an increase of TGF-beta 1 gene expression, thus modulating both HMC proliferation and mesangial matrix production. Images Figure 2 Figure 3 Figure 4 Figure 5 PMID:8952542

  3. Concentrating-collector mass-production feasibility. Volume I. Final report

    SciTech Connect

    Not Available

    1981-11-02

    The Performance Prototype Trough (PPT) Concentrating Collector consists of four 80-foot modules in a 320-foot row. The collector was analyzed, including cost estimates and manufacturing processes to produce collectors in volumes from 100 to 100,000 modules per year. The four different reflector concepts considered were the sandwich reflector structure, sheet metal reflector structure, molded reflector structure, and glass laminate structure. The sheet metal and glass laminate structures are emphasized with their related structure concepts. A preliminary manufacturing plan is offered that includes: documentation of the manufacturing process with production flow diagrams; labor and material costs at various production levels; machinery and equipment requirements including preliminary design specifications; and capital investment costs for a new plant. Of five reflector designs considered, the two judged best and considered at length are thin annealed glass and steel laminate on steel frame panel and thermally sagged glass. Also discussed are market considerations, costing and selling price estimates, design cost analysis and make/buy analysis. (LEW)

  4. 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 ...

  5. Estimating the concentration of aluminum-substituted hematite and goethite using diffuse reflectance spectrometry and rock magnetism: Feasibility and limitations

    NASA Astrophysics Data System (ADS)

    Hu, Pengxiang; Jiang, Zhaoxia; Liu, Qingsong; Heslop, David; Roberts, Andrew P.; Torrent, José; Barrón, Vidal

    2016-06-01

    Hematite and goethite in soils are often aluminum (Al) substituted, which can dramatically change their reflectance and magnetic properties and bias abundance estimates using diffuse reflectance spectroscopy (DRS) and magnetic techniques. In this study, synthetic Al-substituted hematites and goethites and two Chinese loess/paleosol sequences were investigated to test the feasibility and limitations of estimating Al-hematite and Al-goethite concentration. When Al substitution is limited (Al/(Al + Fe) molar ratio < ~8%), the reflectance spectrum provides a reliable estimate of the goethite/hematite concentration ratio. New empirical relationships between the DRS band intensity ratio and the true concentration goethite/hematite ratio are estimated as goethite/hematite = 1.56 × (I425 nm/I535 nm) or goethite/hematite = 6.32 × (I480 nm/I535 nm), where I425 nm, I480 nm, and I535 nm are the amplitudes of DRS second-derivative curves for characteristic bands at ~425 nm, ~480 nm, and ~535 nm, respectively. High Al substitution (> ~8%) reduces DRS band intensity, which leads to biased estimates of mineral concentration. Al substitution and grain size exert a control on coercivity distributions of hematite and goethite and, thus, affect the hard isothermal remanent magnetization. By integrating DRS and magnetic methods, we suggest a way to constrain hematite and goethite Al substitution in natural loess. Results indicate that hematite and goethite in Chinese loess have Al contents lower than ~8% and, thus, that DRS can be used to trace hematite and goethite concentration variations.

  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. Establishing proof of concept: Platelet-rich plasma and bone marrow aspirate concentrate may improve cartilage repair following surgical treatment for osteochondral lesions of the talus

    PubMed Central

    Smyth, Niall A; Murawski, Christopher D; Haleem, Amgad M; Hannon, Charles P; Savage-Elliott, Ian; Kennedy, John G

    2012-01-01

    Osteochondral lesions of the talus are common injuries in the athletic patient. They present a challenging clinical problem as cartilage has a poor potential for healing. Current surgical treatments consist of reparative (microfracture) or replacement (autologous osteochondral graft) strategies and demonstrate good clinical outcomes at the short and medium term follow-up. Radiological findings and second-look arthroscopy however, indicate possible poor cartilage repair with evidence of fibrous infill and fissuring of the regenerative tissue following microfracture. Longer-term follow-up echoes these findings as it demonstrates a decline in clinical outcome. The nature of the cartilage repair that occurs for an osteochondral graft to become integrated with the native surround tissue is also of concern. Studies have shown evidence of poor cartilage integration, with chondrocyte death at the periphery of the graft, possibly causing cyst formation due to synovial fluid ingress. Biological adjuncts, in the form of platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC), have been investigated with regard to their potential in improving cartilage repair in both in vitro and in vitro settings. The in vitro literature indicates that these biological adjuncts may increase chondrocyte proliferation as well as synthetic capability, while limiting the catabolic effects of an inflammatory joint environment. These findings have been extrapolated to in vitro animal models, with results showing that both PRP and BMAC improve cartilage repair. The basic science literature therefore establishes the proof of concept that biological adjuncts may improve cartilage repair when used in conjunction with reparative and replacement treatment strategies for osteochondral lesions of the talus. PMID:22816065

  8. Characteristics of platelet gels combined with silk

    PubMed Central

    Pallotta, Isabella; Kluge, Jonathan A.; Moreau, Jodie; Calabrese, Rossella

    2014-01-01

    Platelet gel, a fibrin network containing activated platelets, is widely used in regenerative medicine due the capacity of platelet-derived growth factors to accelerate and direct healing processes. However, limitations to this approach include poor mechanical properties, relatively rapid degradation, and the lack of control of release of growth factors at the site of injection. These issues compromise the ability of platelet gels for sustained function in regenerative medicine. In the present study, a combination of platelet gels with silk fibroin gel was studied to address the above limitations. Mixing sonicated silk gels with platelet gels extended the release of growth factors without inhibiting gel forming ability. The released growth factors were biologically active and their delivery was modified further by manipulation of the charge of the silk protein. Moreover, the silk gel augmented both the rheological properties and compressive stiffness of the platelet gel, tuned by the silk concentration and/or silk/platelet gel ratio. Silk-platelet gel injections in nude rats supported enhanced cell infiltration and blood vessel formation representing a step towards new platelet gel formulations with enhanced therapeutic impact. PMID:24480538

  9. Characteristics of platelet gels combined with silk.

    PubMed

    Pallotta, Isabella; Kluge, Jonathan A; Moreau, Jodie; Calabrese, Rossella; Kaplan, David L; Balduini, Alessandra

    2014-04-01

    Platelet gel, a fibrin network containing activated platelets, is widely used in regenerative medicine due the capacity of platelet-derived growth factors to accelerate and direct healing processes. However, limitations to this approach include poor mechanical properties, relatively rapid degradation, and the lack of control of release of growth factors at the site of injection. These issues compromise the ability of platelet gels for sustained function in regenerative medicine. In the present study, a combination of platelet gels with silk fibroin gel was studied to address the above limitations. Mixing sonicated silk gels with platelet gels extended the release of growth factors without inhibiting gel-forming ability. The released growth factors were biologically active and their delivery was modified further by manipulation of the charge of the silk protein. Moreover, the silk gel augmented both the rheological properties and compressive stiffness of the platelet gel, tuned by the silk concentration and/or silk/platelet gel ratio. Silk-platelet gel injections in nude rats supported enhanced cell infiltration and blood vessel formation representing a step towards new platelet gel formulations with enhanced therapeutic impact. PMID:24480538

  10. Thrombospondin-induced adhesion of human platelets.

    PubMed Central

    Tuszynski, G P; Kowalska, M A

    1991-01-01

    Washed human unactivated platelets attached and spread on thrombospondin (TSP)-coated microtiter plates. Platelet adhesion was promoted by divalent cations Mn2+, Mg2+, and Ca2+ as compared to buffer having all divalent cations complexed with EDTA. TSP-dependent adhesion was inhibited by anti-TSP fab fragments, an anti-TSP monoclonal antibody, an RGD-containing peptide, complex-specific anti-glycoprotein (GP)IIb-IIIa monoclonal antibodies (A2A9 or AP-2) and anti-VLA-2 monoclonal antibodies (6F1 and Gi9), but not by rabbit preimmune fab fragments, mouse IgG, an anti-GPIIIa monoclonal antibody, or monoclonal antibodies against either the human vitronectin receptor, glycocalicin, or GPIV. At saturating concentrations, anti-GPIIb-IIIa inhibited adhesion by 40-60%. Glanzman's thrombasthenic platelets, which lack GPIIb-IIIa, adhered to TSP to the same extent as anti-GPIIb-IIIa-treated normal platelets or 40-60% as well as untreated normal platelets. Antibody 6F1 (5-10 micrograms/ml) inhibited platelet adhesion of both normal and thrombasthenic platelets by 84-100%. Both VLA-2 antibodies also inhibited collagen-induced platelet adhesion, but had no effect on fibronectin-induced adhesion of normal platelets. These data indicate that platelets specifically adhere to TSP and that this adhesion is mediated through GPIIb-IIIa and/or VLA-2. Images PMID:2010551

  11. 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

    relationship among all the glycoprotein peaks was equal and the only changes observed were quantitative, with young platelets having significantly more membrane glycoprotein per cell than old platelets and normal platelets. Normal platelets had intermediate concentrations of each glycoprotein. These results demonstrate that young platelets are hemostatically more effective in vivo than old platelets. The data are compatible with the hypothesis that platelets age in the circulation by losing membrane fragments and then after becoming senescent, are removed from the circulation by a random process. PMID:7298853

  12. Identification of platelet refractoriness in oncohematologic patients

    PubMed Central

    Ferreira, Aline Aparecida; Zulli, Roberto; Soares, Sheila; de Castro, Vagner; Moraes-Souza, Helio

    2011-01-01

    OBJECTIVES: To identify the occurrence and the causes of platelet refractoriness in oncohematologic patients. INTRODUCTION: Platelet refractoriness (unsatisfactory post-transfusion platelet increment) is a severe problem that impairs the treatment of oncohematologic patients and is not routinely investigated in most Brazilian services. METHODS: Forty-four episodes of platelet concentrate transfusion were evaluated in 16 patients according to the following parameters: corrected count increment, clinical conditions and detection of anti-platelet antibodies by the platelet immunofluorescence test (PIFT) and panel reactive antibodies against human leukocyte antigen class I (PRA-HLA). RESULTS: Of the 16 patients evaluated (median age: 53 years), nine (56%) were women, seven of them with a history of pregnancy. An unsatisfactory increment was observed in 43% of the transfusion events, being more frequent in transfusions of random platelet concentrates (54%). Platelet refractoriness was confirmed in three patients (19%), who presented immunologic and non-immunologic causes. Alloantibodies were identified in eight patients (50%) by the PIFT and in three (19%) by the PRA-HLA. Among alloimmunized patients, nine (64%) had a history of transfusion, and three as a result of pregnancy (43%). Of the former, two were refractory (29%). No significant differences were observed, probably as a result of the small sample size. CONCLUSION: The high rate of unsatisfactory platelet increment, refractoriness and alloimmunization observed support the need to set up protocols for the investigation of this complication in all chronically transfused patients, a fundamental requirement for the guarantee of adequate management. PMID:21437433

  13. 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

  14. 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

  15. A manual method to obtain platelet rich plasma

    PubMed Central

    Marques, Fabiana Paulino; Ingham, Sheila Jean McNeill; Forgas, Andrea; Franciozi, Carlos Eduardo da Silveira; Sasaki, Pedro Henrique; Abdalla, Rene Jorge

    2014-01-01

    OBJECTIVE: This study is to report a manual method to obtain platelet rich plasma (PRP). METHODS: For this study 61 ml of peripheral blood was obtained and submitted to centrifugation at 541g for 5 min. The centrifugation separates the blood into three components: red blood cells, buffy coat and platelet rich plasma. Blood and platelet rich plasma samples were sent to the Hospital's Laboratory and platelets and leukocytes were measured. RESULTS: A sample of 637 blood donors was evaluated. The platelet yield efficiency was 86.77% and the increase in platelet concentration factor was 2.89 times. The increase in leukocyte concentration factor was 1.97 times. CONCLUSION: The method described here produces leukocyte-rich and platelet-rich plasma with a high platelet and leukocyte increased factor. Level of Evidence IV, Controlled Laboratory Study. PMID:24868183

  16. Platelet Inhibition by Nitrite Is Dependent on Erythrocytes and Deoxygenation

    PubMed Central

    Srihirun, Sirada; Sriwantana, Thanaporn; Unchern, Supeenun; Kittikool, Dusadee; Noulsri, Egarit; Pattanapanyasat, Kovit; Fucharoen, Suthat; Piknova, Barbora; Schechter, Alan N.; Sibmooh, Nathawut

    2012-01-01

    Background Nitrite is a nitric oxide (NO) metabolite in tissues and blood, which can be converted to NO under hypoxia to facilitate tissue perfusion. Although nitrite is known to cause vasodilation following its reduction to NO, the effect of nitrite on platelet activity remains unclear. In this study, the effect of nitrite and nitrite+erythrocytes, with and without deoxygenation, on platelet activity was investigated. Methodology/Finding Platelet aggregation was studied in platelet-rich plasma (PRP) and PRP+erythrocytes by turbidimetric and impedance aggregometry, respectively. In PRP, DEANONOate inhibited platelet aggregation induced by ADP while nitrite had no effect on platelets. In PRP+erythrocytes, the inhibitory effect of DEANONOate on platelets decreased whereas nitrite at physiologic concentration (0.1 µM) inhibited platelet aggregation and ATP release. The effect of nitrite+erythrocytes on platelets was abrogated by C-PTIO (a membrane-impermeable NO scavenger), suggesting an NO-mediated action. Furthermore, deoxygenation enhanced the effect of nitrite as observed from a decrease of P-selectin expression and increase of the cGMP levels in platelets. The ADP-induced platelet aggregation in whole blood showed inverse correlations with the nitrite levels in whole blood and erythrocytes. Conclusion Nitrite alone at physiological levels has no effect on platelets in plasma. Nitrite in the presence of erythrocytes inhibits platelets through its reduction to NO, which is promoted by deoxygenation. Nitrite may have role in modulating platelet activity in the circulation, especially during hypoxia. PMID:22276188

  17. Insights into Platelet Storage and the Need for Multiple Approaches.

    PubMed

    Handigund, Mallikarjun; Cho, Yong Gon

    2015-01-01

    Upon accidental injury and the treatment of many diseases, patients may need a transfusion of blood components in order to achieve hemostasis. Platelets are small enucleated cells derived from bone marrow megakaryocytes that undergo change upon activation at sites of vascular injury and play a vital role in vascular repair and antimicrobial host defense, collectively contributing to hemostasis. They are the common blood components transfused whenever there is need, but supplies do not equal the demand as platelets are required in many medical and surgical procedures. In addition, surplus supplies of platelet concentrate are often discarded as they have a short shelf life. Currently, platelet concentrates are stored at room temperature for a maximum of 5 days from the date of collection; the temporal aspect is an added hurdle in the growing demand for platelet concentrates. Many investigations have been carried out in attempt to improve the quality and lengthen the shelf life of platelets, but the few that have succeeded are not commercially viable. Moreover, currently there is a declining trend in platelet research, quelling the hope of platelet storage improvement. Successful strategies would be a boon for medicine in particular and humanity in general. This review deals with past and current efforts toward improving the quality of platelet concentrates by reducing platelet storage lesions and increasing the viable storage period for platelets. Also presented are new perspectives based on past and current efforts, which should be investigated for platelet research in this decade. PMID:26663804

  18. A dynamic magnetic shift method to increase nanoparticle concentration in cancer metastases: a feasibility study using simulations on autopsy specimens

    PubMed Central

    Nacev, Alek; Kim, Skye H; Rodriguez-Canales, Jaime; Tangrea, Michael A; Shapiro, Benjamin; Emmert-Buck, Michael R

    2011-01-01

    A nanoparticle delivery system termed dynamic magnetic shift (DMS) has the potential to more effectively treat metastatic cancer by equilibrating therapeutic magnetic nanoparticles throughout tumors. To evaluate the feasibility of DMS, histological liver sections from autopsy cases of women who died from breast neoplasms were studied to measure vessel number, size, and spatial distribution in both metastatic tumors and normal tissue. Consistent with prior studies, normal tissue had a higher vascular density with a vessel-to-nuclei ratio of 0.48 ± 0.14 (n = 1000), whereas tumor tissue had a ratio of 0.13 ± 0.07 (n = 1000). For tumors, distances from cells to their nearest blood vessel were larger (average 43.8 μm, maximum 287 μm, n ≈ 5500) than normal cells (average 5.3 μm, maximum 67.8 μm, n ≈ 5500), implying that systemically delivered nanoparticles diffusing from vessels into surrounding tissue would preferentially dose healthy instead of cancerous cells. Numerical simulations of magnetically driven particle transport based on the autopsy data indicate that DMS would correct the problem by increasing nanoparticle levels in hypovascular regions of metastases to that of normal tissue, elevating the time-averaged concentration delivered to the tumor for magnetic actuation versus diffusion alone by 1.86-fold, and increasing the maximum concentration over time by 1.89-fold. Thus, DMS may prove useful in facilitating therapeutic nanoparticles to reach poorly vascularized regions of metastatic tumors that are not accessed by diffusion alone. PMID:22131836

  19. 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

  20. 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.

  1. Elevated D-glucose concentrations modulate TGF-beta 1 synthesis by human cultured renal proximal tubular cells. The permissive role of platelet-derived growth factor.

    PubMed Central

    Phillips, A. O.; Steadman, R.; Topley, N.; Williams, J. D.

    1995-01-01

    Interstitial fibrosis is a marker of progression of renal impairment in diabetic nephropathy. Transforming growth factor (TGF)-beta 1 is one of a group of pro-fibrotic cytokines and growth factors that have been associated with the development of interstitial fibrosis. We have examined the modulating influence of glucose on the production of TGF-beta 1 by cultured human proximal tubular cells. Incubation of growth-arrested human proximal tubular cells (HPTC) (72 hours in serum free medium) in 25 mmol/L D-glucose resulted in increased expression of TGF-beta 1 mRNA (as assessed by reverse transcription polymerase chain reaction). This was apparent after 6 hours and increased up to 120 hours exposure. TGF-beta 1 secretion, however, as measured by specific enzyme-linked immunoassay, was unaffected by exposure to 25 mmol/L D-glucose. Sequential stimulation of HPTC, first with 25 mmol/L D-glucose for 48 hours and then with platelet-derived growth factor (PDGF) isoforms, resulted in a dose-dependent secretion of TGF-beta 1. Pre-exposure to 5 mmol/L D-glucose or 25 mmol/L L-glucose did not prime for TGF-beta 1 release. At 50 ng/ml PDGF this effect was greatest for the AA isoform (AA 31.4 +/- 7.1, AB 20.98 +/- 8.9, BB 7.8 +/- 2.2, P < 0.05 for all versus control, n = 3, mean +/- SEM ng/10(6) cells/24 hours). These effects were blocked by the addition of antibody to the PDGF alpha-receptor. TGF-beta 1 secretion was inhibited in a dose-dependent manner by pretreatment with cyclohexamide, but was not affected by pretreatment with actinomycin D. Stimulation of HPTC with a single dose of PDGF induced TGF-beta 1 mRNA; however, only after application of a second dose of PDGF (after TGF-beta 1 mRNA induction) did TGF-beta 1 protein secretion occur. We also demonstrated that PDGF stimulation of HPTC induced an inherently more stable TGF-beta 1 mRNA transcript. These findings demonstrate that elevated D-glucose concentration alone is insufficient to lead to increased TGF-beta 1

  2. Monte Carlo simulation of the heterotypic aggregation kinetics of platelets and neutrophils.

    PubMed

    Laurenzi, I J; Diamond, S L

    1999-09-01

    The heterotypic aggregation of cell mixtures or colloidal particles such as proteins occurs in a variety of settings such as thrombosis, immunology, cell separations, and diagnostics. Using the set of population balance equations (PBEs) to predict dynamic aggregate size and composition distributions is not feasible. The stochastic algorithm of Gillespie for chemical reactions (. J. Comput. Phys. 22:403-434) was reformulated to simulate the kinetic behavior of aggregating systems. The resulting Monte Carlo (MC) algorithm permits exact calculation of the decay rates of monomers and the temporally evolving distribution of sizes and compositions of the aggregates. Moreover, it permits calculation of all moments of these distributions. Using this method, we explored the heterotypic aggregation of fully activated platelets and neutrophils in a linear shear flow of shear rate G = 335 s(-1). At plasma concentrations, the half-lives of homotypically aggregating platelet and neutrophil singlets were 8.5 and 2.4 s, respectively. However, for heterotypic aggregation, the half-lives for platelets and neutrophils decreased to 2.0 and 0.11 s, respectively, demonstrating that flowing neutrophils accelerate capture of platelets and growth of aggregates. The required number of calculations per time step of the MC algorithm was typically a small fraction of Omega(1/2), where Omega is the initial number of particles in the system, making this the fastest MC method available. The speed of the algorithm makes feasible the deconvolution of kernels for general biological heterotypic aggregation processes. PMID:10465782

  3. Bone regeneration with autologous biomaterial; rapid induction of vital new bone in maxillary sinus floor by platelet concentrate alone at 23x baseline (PRP23x): a case report.

    PubMed

    Smith, Astley E; Prasad, Hari S; Rohrer, Michael D

    2009-06-01

    To date, most clinicians and researchers have been using platelet concentrate within the range of 4x to 8x baseline. In this case report a new procedure involving strategic pooling and triple spin was developed and used to concentrate platelets to 23x baseline. The concentrate alone was infused into morselized resorbable collagen sponge, activated with calcium chloride and autologous thrombin, then placed as an autologous graft into the left sinus floor of a healthy 80-year-old woman. The floor of the sinus had approximately 2 mm of bony height. A computed tomography scan taken after 5 months showed that new bone was formed and it was as dense as native bone around the surgical site. From the computed tomography scan bone density analysis using Hounsfield Units revealed that the bone formed was D3 bone (518.3 +/- 224.9 Hounsfield Units) and it was as dense as native bone on the axial, coronal and sagittal slices. Histomorphometric analysis of 2 bone core biopsies taken after 6 months showed that 1 core had 34% bone of which 98% was vital new bone and the other core had 39% bone of which 100% was vital new bone. The height of the bone formed in the sinus floor was 12 mm. It was also characterized by good trabecular pattern and connectivity. The quality of the bone generated was such that 2 endosseous implants were placed and torqued to 30 N cm after the cores were removed. PMID:19509531

  4. Northern elephant seal platelets: analysis of shape change and response to platelet agonists.

    PubMed

    Field, C L; Walker, N J; Tablin, F

    2001-02-15

    Blood platelets have a vital role in the maintenance of normal mammalian hemostasis. Rapid pressure changes and temperatures lower than 20 degrees C cause activation of human and terrestrial mammal platelets. Elephant seals are routinely subjected to pressures as high as 150 atm, yet do not suffer from the thrombotic effects of platelet activation associated with rapid decompression. We examined the ultrastructure of Northern elephant seal (Mirounga angustirostris) platelets and their functional and morphological response to various platelet agonists. Unstimulated elephant seal platelets are discoid cells, with a microtubule coil, randomly dispersed alpha and dense granules, and glycogen granules. There are well-defined areas of membranous invaginations that indicate the presence of an open canalicular system (OCS). Aggregometry was used to determine the response of elephant seal platelets to various platelet agonists. Dose-dependent curves were generated for thrombin, collagen, and adenosine diphosphate (ADP). Platelet response to thrombin was dose-dependent and was maximal at 2.5 U/ml. Platelets collected in sodium citrate had blunted responses to both ADP and collagen. ADP stimulation caused only reversible, primary activation (shape change) at > or = 5 microM, while platelets did not aggregate in response to any concentration of collagen. Platelets collected in sodium heparin did respond fully to both to ADP and collagen. There was small, reversible shape change in response to ristocetin, but no response to epinephrine. Decreased sensitivity of elephant seal platelets to agonists may be a protective mechanism developed in response to rapid pressure changes and cold temperatures associated with adaptation to an extreme environment. PMID:11248288

  5. Platelet antibody detection by flow cytometry: an effective method to evaluate and give transfusional support in platelet refractoriness

    PubMed Central

    Bub, Carolina Bonet; Martinelli, Beatriz Moraes; Avelino, Thayná Mendonça; Gonçalez, Ana Cláudia; Barjas-Castro, Maria de Lourdes; Castro, Vagner

    2013-01-01

    Background Immune platelet refractoriness is mainly caused by human leukocyte antigen antibodies (80-90% of cases) and, to a lesser extent, by human platelet antigen antibodies. Refractoriness can be diagnosed by laboratory tests and patients should receive compatible platelet transfusions. A fast, effective and low cost antibody-screening method which detects platelet human leukocyte/platelet antigen antibodies is essential in the management of immune platelet refractoriness. Objective The aim of this study was to evaluate the efficiency of the flow cytometry platelet immunofluorescence test to screen for immune platelet refractoriness. Methods A group of prospective hematologic patients with clinically suspected platelet refractoriness treated in a referral center in Campinas, SP during July 2006 and July 2011 was enrolled in this study. Platelet antibodies were screened using the flow cytometry platelet immunofluorescence test. Anti-human leukocyte antigen antibodies were detected by commercially available methods. The sensitivity, specificity and predictive values of the immunofluorescence test were determined taking into account that the majority of antiplatelet antibodies presented human leukocyte antigen specificity. Results Seventy-six samples from 32 female and 38 male patients with a median age of 43.5 years (range: 5-84 years) were analyzed. The sensitivity of the test was 86.11% and specificity 75.00% with a positive predictive value of 75.61% and a negative predictive value of 85.71%. The accuracy of the method was 80.26%. Conclusion This study shows that the flow cytometry platelet immunofluorescence test has a high correlation with the anti-human leukocyte antigen antibodies. Despite a few limitations, the method seems to be efficient, fast and feasible as the initial screening for platelet antibody detection and a useful tool to crossmatch platelets for the transfusional support of patients with immune platelet refractoriness. PMID:24106442

  6. Alterations of platelet aggregation kinetics with ultraviolet laser emission: the "stunned platelet" phenomenon.

    PubMed

    Topaz, O; Minisi, A J; Bernardo, N L; McPherson, R A; Martin, E; Carr, S L; Carr, M E

    2001-10-01

    Platelets, a major constituent of thrombus, play a crucial role in the pathogenesis of acute ischemic coronary syndromes. The effect of ultraviolet laser emission on platelets within thrombi is unknown. The effects of increasing levels of laser energy on platelets in whole blood were investigated. Blood samples were obtained by aseptic venipuncture and anticoagulated with 3.8% sodium citrate. Samples were exposed to increased levels (0, 30, 45, 60 mJ/mm2; 25 Hz) of ultraviolet excimer laser fluence (308 nm wave-length) and then tested for ADP and collagen induced platelet aggregation, platelet concentration, and for platelet contractile force (PCF) development. Scanning electron microscopy was used to detect laser induced morphologic changes of platelets and by flow cytometric analysis to detect changes in expression of platelet surface antigens p-selectin (CD 62) and glycoprotein IIb/IIIa (CD 43). Exposure to excimer laser energy produced dose dependent suppression of platelet aggregation and force development ("stunned platelets"). ADP aggregation decreased from 8.0+/-1.1 Ohms (mean+/-SEM) to 3.7+/-0.8 Ohms (p<0.001) to 2.7+/-0.6 Ohms (p <0.001) and to 1.8+/-0.5 Ohms (p <0.001) as the laser energy increased from 0 to 30 to 45 to 60 mJ/mm2, respectively. Collagen induced aggregation decreased from 21.4+/-1.4 Ohms to 15.7+/-1.2 Ohms (p <0.001) to 11.7+/-1.1 Ohms (p <0.001) and to 9.9+/-1.0 Ohms (p <0.001), in response to the same incremental range of laser energy. Platelet contractile forces declined from 34,500+/-3700 to 27.800+/-2700 dynes as laser energy increased from 0 to 60 mJ/mm2 (p <0.03). Platelet concentration did not change with increasing laser energy. The expression of platelet surface antigen p-selectin (CD 62) remained stable through increasing levels of laser energy exposures while the percentage of CD 43 positive platelets significantly increased with exposure to laser energy, yet the level of expression did not exceed 0.5% of cells. Thus

  7. Clinical application of radiolabelled platelets

    SciTech Connect

    Kessler, C. )

    1990-01-01

    This book presents papers on the clinical applications of radiolabelled platelets. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection.

  8. 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

  9. 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 ...

  10. A new C-type lectin (RVsnaclec) purified from venom of Daboia russelii russelii shows anticoagulant activity via inhibition of FXa and concentration-dependent differential response to platelets in a Ca²⁺-independent manner.

    PubMed

    Mukherjee, Ashis K; Dutta, Sumita; Mackessy, Stephen P

    2014-11-01

    This is the first report on the characterization of a snaclec (RVsnaclec) purified from Daboia russelii russelii venom. The RVsnaclec is a heterodimer of two subunits, α (15.1 kDa) and β (9 kDa). These subunits are covalently linked to form multimeric (αβ)₂ and (αβ)₄ structures. Peptide mass fingerprinting analysis of RVsnaclec via LC-MS/MS demonstrated its similarity to snaclecs purified from other viperid snake venoms. Two tryptic peptide sequences of RVsnaclec revealed the putative conserved domains of C-type lectin (CTL). RVsnaclec dose-dependently increased the Ca-clotting time and prothrombin time of platelet-poor plasma (PPP); however, it did not affect the partial thromboplastin time (APTT) or thrombin time of PPP. The in vitro and in vivo anticoagulant activity of RVsnaclec is correlated to its binding and subsequent uncompetitive inhibition of FXa (Ki = 0.52 μmole) in a Ca(2+)-independent manner; however, supplementation with 0.25 mM Ca(2+) enhanced the Xa binding potency of RVsnaclec. Monovalent or polyvalent antivenom failed to neutralize its anticoagulant potency, and RVsnaclec did not inhibit trypsin, chymotrypsin, thrombin or plasmin. RVsnaclec was devoid of hemolytic activity or cytotoxicity against several human cancer cell lines, demonstrated concentration-dependent aggregation and deaggregation of human platelets, and inhibited the ADP-induced aggregation of platelet. RVsnaclec (5.0 mg/kg body weight) was non-lethal to mice and showed no adverse pharmacological effects, suggesting that it has potential as a lead compound for future therapeutic applications in cardiovascular disorders. PMID:25281435

  11. Platelets contribute to growth and metastasis in hepatocellular carcinoma.

    PubMed

    Bihari, Chhagan; Rastogi, Archana; Shasthry, Saggere Muralikrishna; Bajpai, Meenu; Bhadoria, Ajeet Singh; Rajesh, S; Mukund, Amar; Kumar, Anupam; Sarin, Shiv K

    2016-09-01

    To determine the association of platelets with hepatocellular carcinoma (HCC) growth and its metastasis. We examined platelets, laboratory, and radiological data of consecutive 420 HCC and 1008 cirrhosis cases. Follow-up information of platelet count in cirrhosis to HCC, pre- to post-therapy, and post-therapy to HCC outcome was analyzed. Cytokine profiling was performed in HCC and cirrhosis (n = 10 each). On the basis of imaging, HCC was divided into six subgroups. Cytosmears of HCC were assessed for platelet clustering around tumor cells. An in vitro Matrigel invasion assay was performed on human HCC cell lines using graded concentration of platelets. Baseline platelet numbers and platelet/lymphocyte ratios (PLRs) were significantly higher (p < 0.001) in HCC than cirrhosis. IL-1, IL-6, FGF, G-CSF, thrombopoietin, and VEGF were higher in HCC than cirrhosis. Platelet counts were increased after HCC conversion of cirrhosis (p < 0.001) and decreased (p < 0.001) after therapy. Platelets and PLR in recurrence cases were higher than in responders at baseline. AFP, PIVKAII, platelets, and PLR increase (p < 0.001 each) with advancement in HCC growth. Multivariate analysis showed platelets (p = 0.002), PLR (p = 0.004), and AFP (p < 0.001) associated with distant metastasis. Platelet clustering seen in 75.7% of HCC group 3, 45% in group 2, and 12.5% in group 1 cases (p < 0.001). Invaded cells in Matrigel assay positively correlated with platelet concentration. Platelets can contribute to the development, growth, invasion, and metastasis of HCC. Rising platelet count after HCC therapy is indicative of incomplete response or recurrence. PMID:27457354

  12. Use of mean platelet component to measure platelet activation on the ADVIA 120 haematology system.

    PubMed

    Macey, M G; Carty, E; Webb, L; Chapman, E S; Zelmanovic, D; Okrongly, D; Rampton, D S; Newland, A C

    1999-10-15

    Platelet activation results in changes in a number of cell surface molecules including an increase in P-Selectin (CD62P) that may be rapidly and conveniently measured by immunofluorescent flow cytometry. The ADVIA 120 (Bayer) is a new system that facilitates more accurate measurement of platelet volume and in addition provides an approximate measure of the mean refractive index (RI) of the platelets reported as mean platelet component (MPC) concentration. We were interested to determine whether changes in MPC might reflect changes in platelet activation status. To investigate this, the platelet CD62P expression, determined by flow cytometry, and change in MPC, measured on the ADVIA 120 system, was first examined in vitro after stimulation of EDTA anticoagulated whole blood with submaximal concentrations of bovine thrombin in the presence or absence of the thromboxane synthase inhibitor, Ridogrel. Thrombin produced a dose-dependent increase in platelet CD62P expression and a decrease in MPC that could be inhibited by Ridogrel at physiological concentrations. In the second set of experiments, blood from 20 normal controls was collected into both EDTA and sodium citrate (SC) anticoagulants. Within 30 min of venesection and again at 3 h post-venesection after storage at room temperature, the platelet MPC and CD62P expression were determined. Platelets in all samples with both anticoagulants showed very low levels of CD62P expression when first analysed. At 3 h there was a small increase in CD62P expression on platelets in whole blood anticoagulated with SC, but a significant (P < 0.001) increase was observed on platelets anti-coagulated with EDTA. A negative correlation was found between the change in MPC of the platelets and the increase in the mean fluorescence intensity (MFI) (r = -0.69, P < 0.001, n = 20) and the percentage (r = -0.72, P < 0.001, n = 20) of CD62P positive platelets at 3 h in blood anticoagulated with EDTA. We conclude that a reduction in MPC as

  13. A randomised controlled feasibility study investigating the use of eccentric and concentric strengthening exercises in the treatment of rotator cuff tendinopathy

    PubMed Central

    Adams, Nicola

    2014-01-01

    Objectives: To conduct a feasibility study to compare concentric and eccentric rotator cuff strengthening exercises for rotator cuff tendinopathy. Methods: A total of 11 patients with rotator cuff tendinopathy who were on the waiting list for arthroscopic subacromial decompression surgery were randomised to perform eccentric rotator cuff strengthening exercises, concentric strengthening exercises or no exercises. Patients were evaluated in terms of levels of pain and function using the Oxford Shoulder Score and a Visual Analogue Scale initially, at 4 weeks and at 8 weeks. Results: The study design was found to be acceptable to patients and achieved a high level of 86% compliance. The drop-out rate was 0%. Two patients performing eccentric strengthening exercises improved sufficiently to cancel their planned surgery. Conclusion: Further research in this area is recommended. The study design was feasible and power calculations have been conducted to aid future research planning. PMID:26770702

  14. Rhesus monkey platelets

    SciTech Connect

    Harbury, C.B.

    1986-03-01

    The purpose of this abstract is to describe the adenine nucleotide metabolism of Rhesus monkey platelets. Nucleotides are labelled with /sup 14/C-adenine and extracted with EDTA-ethanol (EE) and perchlorate (P). Total platelet ATP and ADP (TATP, TADP) is measured in the Holmsen Luciferase assay, and expressed in nanomoles/10/sup 8/ platelets. TR=TATP/TADP. Human platelets release 70% of their TADP, with a ratio of released ATP/ADP of 0.7. Rhesus platelets release 82% of their TADP, with a ratio of released ATP/ADP of 0.33. Thus, monkey platelets contain more ADP than human platelets. Thin layer chromatography of EE gives a metabolic ratio of 11 in human platelets and 10.5 in monkey platelets. Perchlorate extracts metabolic and actin bound ADP. The human and monkey platelets ratios were 5, indicating they contain the same proportion of actin. Thus, the extra ADP contained in monkey platelets is located in the secretory granules.

  15. Platelets in Lung Biology

    PubMed Central

    Weyrich, Andrew S.; Zimmerman, Guy A.

    2013-01-01

    Platelets and the lungs have an intimate relationship. Platelets are anucleate mammalian blood cells that continuously circulate through pulmonary vessels and that have major effector activities in hemostasis and inflammation. The lungs are reservoirs for megakaryocytes, the requisite precursor cell in thrombopoiesis, which is the intricate process by which platelets are generated. Platelets contribute to basal barrier integrity of the alveolar capillaries, which selectively restricts the transfer of water, proteins, and red blood cells out of the vessels. Platelets also contribute to pulmonary vascular repair. Although platelets bolster hemostatic and inflammatory defense of the healthy lung, experimental evidence and clinical evidence indicate that these blood cells are effectors of injury in a variety of pulmonary disorders and syndromes. Newly discovered biological capacities of platelets are being explored in the context of lung defense, disease, and remodeling. PMID:23043249

  16. Platelets and galectins

    PubMed Central

    2014-01-01

    A major function of platelets is keeping the vascular system intact. Platelet activation at sites of vascular injury leads to the formation of a hemostatic plug. Activation of platelets is therefore crucial for normal hemostasis; however, uncontrolled platelet activation may also lead to the formation of occlusive thrombi that can cause ischemic events. Although they are essential for proper hemostasis, platelet function extends to physiologic processes such as tissue repair, wound remodeling and antimicrobial host defense, or pathologic conditions such as thrombosis, atherosclerosis, chronic inflammatory diseases and cancer. Platelets can be activated by soluble molecules including thrombin, thromboxane A2 (TXA2), adenosine diphosphate (ADP), serotonin or by adhesive extracellular matrix (ECM) proteins such as von Willebrand factor (vWF) and collagen. Here we describe recent advances in the activation of platelets by non-canonical platelet agonists such as galectins. By acting either in soluble or immobilized form, these glycan-binding proteins trigger all platelet activation responses through modulation of discrete signaling pathways. We also offer new hypotheses and some speculations about the role of platelet-galectin interactions not only in hemostasis and thrombosis but also in inflammation and related diseases such as atherosclerosis and cancer. PMID:25405160

  17. 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

  18. 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

  19. Improving platelet transfusion safety: biomedical and technical considerations.

    PubMed

    Garraud, Olivier; Cognasse, Fabrice; Tissot, Jean-Daniel; Chavarin, Patricia; Laperche, Syria; Morel, Pascal; Lefrère, Jean-Jacques; Pozzetto, Bruno; Lozano, Miguel; Blumberg, Neil; Osselaer, Jean-Claude

    2016-03-01

    Platelet concentrates account for near 10% of all labile blood components but are responsible for more than 25% of the reported adverse events. Besides factors related to patients themselves, who may be particularly at risk of side effects because of their underlying illness, there are aspects of platelet collection and storage that predispose to adverse events. Platelets for transfusion are strongly activated by collection through disposal equipment, which can stress the cells, and by preservation at 22 °C with rotation or rocking, which likewise leads to platelet activation, perhaps more so than storage at 4 °C. Lastly, platelets constitutively possess a very large number of bioactive components that may elicit pro-inflammatory reactions when infused into a patient. This review aims to describe approaches that may be crucial to minimising side effects while optimising safety and quality. We suggest that platelet transfusion is complex, in part because of the complexity of the "material" itself: platelets are highly versatile cells and the transfusion process adds a myriad of variables that present many challenges for preserving basal platelet function and preventing dysfunctional activation of the platelets. The review also presents information showing--after years of exhaustive haemovigilance--that whole blood buffy coat pooled platelet components are extremely safe compared to the gold standard (i.e. apheresis platelet components), both in terms of acquired infections and of immunological/inflammatory hazards. PMID:26674828

  20. Improving platelet transfusion safety: biomedical and technical considerations

    PubMed Central

    Garraud, Olivier; Cognasse, Fabrice; Tissot, Jean-Daniel; Chavarin, Patricia; Laperche, Syria; Morel, Pascal; Lefrère, Jean-Jacques; Pozzetto, Bruno; Lozano, Miguel; Blumberg, Neil; Osselaer, Jean-Claude

    2016-01-01

    Platelet concentrates account for near 10% of all labile blood components but are responsible for more than 25% of the reported adverse events. Besides factors related to patients themselves, who may be particularly at risk of side effects because of their underlying illness, there are aspects of platelet collection and storage that predispose to adverse events. Platelets for transfusion are strongly activated by collection through disposal equipment, which can stress the cells, and by preservation at 22 °C with rotation or rocking, which likewise leads to platelet activation, perhaps more so than storage at 4 °C. Lastly, platelets constitutively possess a very large number of bioactive components that may elicit pro-inflammatory reactions when infused into a patient. This review aims to describe approaches that may be crucial to minimising side effects while optimising safety and quality. We suggest that platelet transfusion is complex, in part because of the complexity of the “material” itself: platelets are highly versatile cells and the transfusion process adds a myriad of variables that present many challenges for preserving basal platelet function and preventing dysfunctional activation of the platelets. The review also presents information showing - after years of exhaustive haemovigilance - that whole blood buffy coat pooled platelet components are extremely safe compared to the gold standard (i.e. apheresis platelet components), both in terms of acquired infections and of immunological/inflammatory hazards. PMID:26674828

  1. Design and feasibility of high temperature nanoparticle fluid filter in hybrid thermal/photovoltaic concentrating solar power

    NASA Astrophysics Data System (ADS)

    DeJarnette, Drew; Brekke, Nick; Tunkara, Ebrima; Hari, Parameswar; Roberts, Kenneth; Otanicar, Todd

    2015-09-01

    A nanoparticle fluid filter used with concentrating hybrid solar/thermal collector design is presented. Nanoparticle fluid filters could be situated on any given concentrating system with appropriate customized engineering. This work shows the design in the context of a trough concentration system. Geometric design and physical placement in the optical path was modeled using SolTrace. It was found that a design can be made that blocks 0% of the traced rays. The nanoparticle fluid filter is tunable for different concentrating systems using various PV cells or operating at varying temperatures.

  2. Increased Platelet Reactivity Is Associated with Circulating Platelet-Monocyte Complexes and Macrophages in Human Atherosclerotic Plaques

    PubMed Central

    Vrijenhoek, Joyce E. P.; van Holten, Thijs C.; Elsenberg, Ellen H. A. M.; Mak-Nienhuis, Elske M.; de Borst, Gert Jan; Jukema, J. Wouter; Pijls, Nico H. J.; Waltenberger, Johannes; van Zonneveld, Anton Jan; Moll, Frans L.; McClellan, Elizabeth; Stubbs, Andrew; Pasterkamp, Gerard; Hoefer, Imo; de Groot, Philip G.; Roest, Mark

    2014-01-01

    Objective Platelet reactivity, platelet binding to monocytes and monocyte infiltration play a detrimental role in atherosclerotic plaque progression. We investigated whether platelet reactivity was associated with levels of circulating platelet-monocyte complexes (PMCs) and macrophages in human atherosclerotic carotid plaques. Methods Platelet reactivity was determined by measuring platelet P-selectin expression after platelet stimulation with increasing concentrations of adenosine diphosphate (ADP), in two independent cohorts: the Circulating Cells cohort (n = 244) and the Athero-Express cohort (n = 91). Levels of PMCs were assessed by flow cytometry in blood samples of patients who were scheduled for percutaneous coronary intervention (Circulating Cells cohort). Monocyte infiltration was semi-quantitatively determined by histological examination of atherosclerotic carotid plaques collected during carotid endarterectomy (Athero-Express cohort). Results We found increased platelet reactivity in patients with high PMCs as compared to patients with low PMCs (median (interquartile range): 4153 (1585–11267) area under the curve (AUC) vs. 9633 (3580–21565) AUC, P<0.001). Also, we observed increased platelet reactivity in patients with high macrophage levels in atherosclerotic plaques as compared to patients with low macrophage levels in atherosclerotic plaques (mean±SD; 8969±3485 AUC vs. 7020±3442 AUC, P = 0.02). All associations remained significant after adjustment for age, sex and use of drugs against platelet activation. Conclusion Platelet reactivity towards ADP is associated with levels of PMCs and macrophages in human atherosclerotic carotid plaques. PMID:25122139

  3. Consumption of both low and high (-)-epicatechin apple puree attenuates platelet reactivity and increases plasma concentrations of nitric oxide metabolites: a randomized controlled trial.

    PubMed

    Gasper, Amy; Hollands, Wendy; Casgrain, Amelie; Saha, Shikha; Teucher, Birgit; Dainty, Jack R; Venema, Dini P; Hollman, Peter C; Rein, Maarit J; Nelson, Rebecca; Williamson, Gary; Kroon, Paul A

    2014-10-01

    We hypothesised that consumption of flavanol-containing apple puree would modulate platelet activity and increase nitric oxide metabolite status, and that high flavanol apple puree would exert a greater effect than low flavanol apple puree. 25 subjects consumed 230 g of apple puree containing 25 and 100mg epicatechin (low and high flavanol apple puree, respectively) and aspirin (75 mg) in random order. Measurements were made at baseline, acutely after treatment (2, 6 and 24 h), and after 14 d of treatment. Low flavanol apple puree significantly attenuated ADP and epinephrine-induced integrin-β3 expression 2 h and 6 h after consumption and ADP and epinephrine-induced P-selectin expression within 2h of consumption. High flavanol apple puree attenuated epinephrine and ADP-induced integrin-β3 expression after 2 and 6h. ADP and epinephrine-induced integrin-β3 expression was significantly attenuated 2, 6 and 24 h after consumption of aspirin, whilst 14 d aspirin consumption attenuated collagen-induced P-selectin expression only. The plasma total nitric oxide metabolite conc. was significantly increased 6h after consumption of both low and high flavanol apple purees. In conclusion, consumption of apple purees containing ⩾25 or 100 mg flavanols transiently attenuated ex vivo integrin-β3 and P-selectin expression and increased plasma nitric oxide metabolite conc. in healthy subjects, but the effect was not enhanced for the high flavanol apple puree. PMID:24929184

  4. Formulation and Storage of Platelet-Rich Plasma Homemade Product

    PubMed Central

    Giraudo, Laurent; Veran, Julie; Magalon, Jeremy; Coudreuse, Jean-Marie; Magalon, Guy; Dubois, Christophe; Serratrice, Nicolas; Dignat-George, Françoise; Sabatier, Florence

    2012-01-01

    Abstract The platelet-rich plasma (PRP) is an autologous biotherapy based on platelet-healing properties. Here, we developed a simple and reproducible PRP purification protocol based on two successive centrifugations. We evaluated different centrifugation speeds and time-storage durations on the platelet quantity and quality. Sterility and stability of our PRP homemade product were also performed. We prepared PRP from 54 healthy volunteers. We tested activation state, reactivity, and stability of platelets by flow cytometry using basal and adenosine diphosphate (ADP)-induced P-selectin expression markers; growth factor release after platelet activation by an enzyme-linked immunosorbent assay (ELISA); platelet aggregation capacity by aggregrometry assays; clot formation and retraction by thromboelastography; and platelet morphology by ultrastructural analysis. About 130 and 250 g successive speed centrifugations further concentrated platelets while preserving their bioactivity during 6 h (after that, platelet functions were significantly altered). In these conditions, we obtained a highly concentrated pure PRP product (with a low leukocyte count) suitable to study platelet properties. To avoid the loss of efficacy, we recommend injecting PRP under 3 h after preparation. PMID:23516671

  5. Analysis of aggregation of platelets in thrombosis

    NASA Astrophysics Data System (ADS)

    Ahuja, Suresh

    Platelets are key players in thrombus formation by first rolling over collagen bound von Willebrand factor followed by formation of a stable interaction with collagen. The first adhered platelets bind additional platelets until the whole injury is sealed off by a platelet aggregate. The coagulation system stabilizes the formed platelet plug by creating a tight fibrin network, and then wound contraction takes place because of morphological changes in platelets. Coagulation takes place by platelet activation and aggregation mainly through fibrinogen polymerization into fibrin fibers. The process includes multiple factors, such as thrombin, plasmin, and local shear-rate which regulate and control the process. Coagulation can be divided into two pathways: the intrinsic pathway and the extrinsic pathway. The intrinsic pathway is initiated by the exposure of a negatively charged. It is able to activate factor XII, using a complex reaction that includes prekallikrein and high-molecular-weight kininogen as cofactors.. Thrombin is the final enzyme that is needed to convert fibrinogen into fibrin. The extrinsic pathway starts with the exposure of tissue factor to the circulating blood, which is the major initiator of coagulation. There are several feedback loops that reinforce the coagulation cascade, resulting in large amounts of thrombin. It is dependent on the presence of pro-coagulant surfaces of cells expressing negatively charged phospholipids--which include phosphatidylserine (PS)--on their outer membrane. PS-bearing surfaces are able to increase the efficiency of the reactions by concentrating and co-localizing coagulation factors.. Aggregation of platelets are analyzed and compared to adhesion of platelet to erythrocyte and to endothelial cells. This abstract is replacing MAR16-2015-020003.

  6. Platelet storage media.

    PubMed

    Gulliksson, H

    2014-10-01

    Present platelet storage media often designated platelet additive solutions (PAS) basically contain acetate, citrate and phosphate and recently also potassium and magnesium. However, there seems to be an increasing interest in developing PASs that can be used also after further reduction of residual plasma content below 15-20% plasma. Inclusion of glucose but also calcium and bicarbonate in such solutions have been suggested to improve platelet (PLT) storage, especially when plasma content is reduced to very low levels. Results from a limited number of studies using novel PAS alternatives have been presented during the last years, such as InterSol-G, PAS-5, M-sol, PAS-G and SAS. Most of them are experimental solutions. The combined results presented in those studies suggest that presence of glucose may be necessary during PLT storage, primarily to maintain ATP at acceptable levels. At plasma inclusion below 15-20%, the content of glucose will generally be too low to support PLT metabolism for more than a few days making glucose addition in PAS necessary. Significant effects associated with presence of calcium was observed in PLTs stored in PAS with 5% inclusion but not with 20-35% plasma inclusion, suggesting that the content of plasma could be of importance. Bicarbonate only seems to be of importance for pH regulation, primarily when plasma inclusion is reduced to about 5%. Reduction in rate of glycolysis was observed in some PAS alternatives containing potassium and magnesium but not in others. Differences in pH or in concentrations of the various compounds included in PAS may be possible explanations. Additionally, novel PAS containing glucose, calcium and bicarbonate does not seem to be associated with improved in vitro results as compared to SSP+ or CompoSol when PLTs are stored with 35% plasma inclusion. The results would then also suggest that excess of glucose in novel PAS environment may not be associated with additional positive effects on PLT metabolism

  7. 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

  8. Platelets enhance neutrophil transendothelial migration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Platelets are increasingly recognized as important mediators of inflammation in addition to thrombosis. While platelets have been shown to promote neutrophil (PMN) adhesion to endothelium in various inflammatory models, it is unclear whether platelets enhance neutrophil transmigration across inflame...

  9. Chrono-lume and magnesium potentiate aggregation of canine but not human platelets in citrated platelet-rich plasma.

    PubMed

    Callan, M B; Shofer, F S; Wojenski, C; Giger, U

    1998-07-01

    The effects of Chrono-lume (CL) and magnesium sulfate (Mg2+), a component of this luciferin-luciferase reagent, on platelet aggregation were studied in platelet-rich plasma (PRP) obtained from blood anticoagulated with sodium citrate from humans, dogs, cats, horses, and cows. The final added Mg2+ concentration of both solutions ranged from 0.75-3.7 mM. CL and Mg2+ had no effect on maximum aggregation of platelets from humans induced by sub-threshold concentrations of collagen and ADP. In contrast, addition of CL or Mg2+ to canine PRP resulted in a dose-dependent and equal potentiation of platelet aggregation in response to sub-threshold concentrations of collagen, ADP, and thrombin in normal and thrombopathic dogs. The effect of CL on platelet aggregation induced by sub-threshold concentrations of agonists was less pronounced and varied in other species according to the agonist. The reason for the marked difference in sensitivity of human and canine platelets to CL or Mg2+ is not clear, although a difference in releasable cation pools of the platelets from these two species has been recognized. Platelet aggregation studies of animals with suspected thrombopathias should be performed without CL to prevent masking of a platelet function defect. PMID:9684806

  10. 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.

  11. Dose-dependent platelet stimulation and inhibition induced by anti-PIA1 IgG

    SciTech Connect

    Ryu, T.; Davis, J.M.; Schwartz, K.A. )

    1990-07-01

    The PIA1 antibody produces several clinically distinct and severe thrombocytopenias. Investigations have demonstrated divergent effects on platelet function; prior reports demonstrated inhibition, while a conflicting publication showed platelet activation. We have resolved this conflict using anti-PIA1 IgG produced by a patient with posttransfusion purpura. Relatively low concentrations stimulated platelet aggregation and release of adenosine triphosphate (ATP) whereas high concentrations inhibited platelet function, producing a thrombasthenia-like state. The number of molecules of platelet-associated IgG necessary to initiate aggregation and ATP release (2,086 +/- 556) or produce maximum aggregation (23,420 +/- 3,706) or complete inhibition (63,582 +/- 2654) were measured with a quantitative radiometric assay for bound anti-PIA1. Preincubation of platelets with high concentrations of PIA1 antibody inhibited platelet aggregation with 10 mumol/L adenosine diphosphate and blocked 125I-labeled fibrinogen platelet binding. Platelet activation with nonfibrinogen dependent agonist, 1 U/ml thrombin, was not inhibited by this high concentration of PIA1 IgG. In conclusion, anti-PIAI IgG produces (1) stimulation of platelet aggregation and ATP release that is initiated with 2000 molecules IgG per platelet and is associated with an increase of 125I-fibrinogen binding; (2) conversely, inhibition of platelet aggregation is observed with maximum antibody binding, 63,000 molecules IgG per platelet, and is mediated via a blockade of fibrinogen binding.

  12. 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

  13. Inherited platelet disorders.

    PubMed

    Sandrock-Lang, Kirstin; Wentzell, Rüdiger; Santoso, Sentot; Zieger, Barbara

    2016-08-01

    Inherited platelet disorders may be the cause of bleeding symptoms of varying severity as platelets fail to fulfil their haemostatic role after vessel injury. Platelet disorders may be difficult to diagnose (and are likely to be misdiagnosed) and raise problems in therapy and management. This review explores the clinical and molecular genetic phenotype of several inherited disorders. Inherited platelet disorders can be classified according to their platelet defects: receptor defects (adhesion or aggregation), secretion disorder, and cytoskeleton defects. The best characterized platelet receptor defects are Glanzmann thrombasthenia (integrin αIIbβ3 defect) and Bernard-Soulier syndrome (defect of GPIb/IX/V). Detailed case reports of patients suffering from Glanzmann thrombasthenia (GT) or Bernard-Soulier syndrome (BSS) showing the bleeding diathesis as well as investigation of platelet aggregation/agglutination and platelet receptor expression will complement this review. In addition, Hermansky-Pudlak syndrome (HPS) as an important defect of δ-granule secretion is extensively described together with a case report of a patient suffering from HPS type 1. PMID:25707719

  14. 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 ...

  15. Platelet Donation (Apheresis)

    MedlinePlus

    ... may be ideal for a simultaneous platelet and plasma donation. Anyone in need can receive your plasma, it is universal. Only 4% of the U.S. ... can donate up to 24 times per year. Plasma can be collected simultaneously with a platelet donation. ...

  16. Dose response of surfactants to attenuate gas embolism related platelet aggregation

    NASA Astrophysics Data System (ADS)

    Eckmann, David M.; Eckmann, Yonaton Y.; Tomczyk, Nancy

    2014-03-01

    Intravascular gas embolism promotes blood clot formation, cellular activation, and adhesion events, particularly with platelets. Populating the interface with surfactants is a chemical-based intervention to reduce injury from gas embolism. We studied platelet activation and platelet aggregation, prominent adverse responses to blood contact with bubbles. We examined dose-response relationships for two chemically distinct surfactants to attenuate the rise in platelet function stimulated by exposure to microbubbles. Significant reduction in platelet aggregation and platelet activation occurred with increasing concentration of the surfactants, indicating presence of a saturable system. A population balance model for platelet aggregation in the presence of embolism bubbles and surfactants was developed. Monte Carlo simulations for platelet aggregation were performed. Results agree qualitatively with experimental findings. Surfactant dose-dependent reductions in platelet activation and aggregation indicate inhibition of the gas/liquid interface's ability to stimulate cellular activation mechanically.

  17. Formed platelets for low cost regeneratively cooled rocket combustion chambers

    NASA Astrophysics Data System (ADS)

    Burkhardt, Wendel M.

    1992-02-01

    The ongoing work performed to demonstrate the fabrication feasibility of a formed platelet regeneratively cooled combustion chamber liner is described. The combustion chambers are fabricated in three or four axial sections from formed platelet stacks joined together. The platelets are etched, stacked, and bonded into flat panels that contain the regen passages. The flat panels are formed into the final contour with a die. The formed platelet approach takes advantage of the inherent low cost, high accuracy, and thin wall capability of photoetched platelet technology to fabricate long life, low cost rocket combustion chambers. Combustion chamber liner sections were fabricated with extremely thin (tw = 0.20 mm (0.008-in.)) hot gas side walls and very high aspect ratio coolant channels (aspect ratio greater than 10:1). Combustion chamber liner sections were formed of both Zr-Cu and stainless steel. The results of both the forming of individual panels and the joining of panels together are discussed. Work performed demonstrating the feasibility of rocket combustion chamber liners from formed platelets is described. A discussion of the benefits of chamber liners so constructed and of a chamber producing 176,000 N (40 Klbf) of thrust currently fabricated is presented. The results of a study examining the forming of large scale platelet panels for an Space Shuttle Main Engine (SSME) Main Combustion Chamber (MCC) liner are included.

  18. [Indications and surveillance of platelet transfusions in surgery].

    PubMed

    Coffe, C; Bardiaux, L; Couteret, Y; Devillers, M; Leroy, M; Morel, P; Pouthier-Stein, F; Hervé, P

    1995-01-01

    Surgery, after hematology, is the biggest consumer of homologous platelet concentrates. Platelet transfusion is indicated to prevent or control bleeding associated with deficiencies in platelet number or function. In surgery, general patterns (in function of pre-surgery platelet count) can be adopted in most of the indications for platelets. In emergency situations, and in some particular cases (related to the patient, the type of operation, etc.), the transfusion procedure depends on the team's experience, the results of the available clinical and biological tests, and the drugs. Strict monitoring is required during the transfusion procedure. The efficacy of the transfusion must be controlled 1 h and 24 hours after the transfusion, and a number of factors must be assessed, namely the immunological impact of the transfusion (on red blood cells, leukocytes and platelets) and the occurrence of infectious diseases transmitted via transfusion. In addition, for a possible future transfusion, a strategy must be proposed. PMID:7767484

  19. 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

  20. Cardiac and vascular imaging with labeled platelets and leukocytes

    SciTech Connect

    Dewanjee, M.K.

    1984-07-01

    The contribution of platelets in atherosclerosis and thrombosis in animal models and in clinical studies has been quantified with 111In-platelet scintigraphy. New in vitro quantitative techniques have been developed using 111In-labeled platelets to determine the number of adherent platelets on deendothelialized surfaces of damaged vessel walls and synthetic vascular grafts. In vivo imaging techniques are semi-quantitative in nature; in these studies 111In radioactivity on thrombotic vessels or graft surfaces of iliac, femoral, or popliteal arteries is compared with contralateral vessels. Background 111In radioactivity in the circulating blood pool of venous and capillary networks and radioactivity in marrow decreases the sensitivity of these techniques. Subtraction of blood pool radioactivity with 99mTc-labeled autologous red cells and calculation of 111In radioactivity associated with platelet thrombus on vessel walls also have been performed for coronary, carotid, and femoral arteries. Although platelet concentrates are used frequently after open heart surgery (one to six per patient), consumption of platelets in the artificial lung or oxygenator, lysis of platelets during pumping, and suction of blood only recently have been quantified with the use of 111In-labeled platelets. These studies also demonstrated far less trauma to platelets with the use of a membrane rather than a bubble oxygenator. Further reduction in platelet consumption and trauma was observed with the use of prostacyclin, a short-acting drug with significant beneficial effect on platelet thrombus reduction and disaggregation of aggregated platelets. The role of polymorphonuclear leukocytes in inflammation, infection and myocardial infarction, and in vivo evaluation with 111In-leukocyte scintigraphy in animals and humans has been described.

  1. The content of bone morphogenetic proteins in platelets varies greatly between different platelet donors

    SciTech Connect

    Kalen, Anders; Wahlstroem, Ola; Linder, Cecilia Halling; Magnusson, Per

    2008-10-17

    Platelet derivates and platelet rich plasma have been used to stimulate bone formation and wound healing because of the rich content of potent growth factors. However, not all reports have been conclusive since some have not been able to demonstrate a positive effect. We investigated the interindividual variation of bone morphogenetic proteins (BMPs) in platelets from healthy donors, and the pH-dependent effect on the release of BMPs in preparations of lysed platelets in buffer (LPB). Platelet concentrates from 31 healthy donors were prepared in pH 4.3 and pH 7.4 buffers and investigated with respect to BMP-2, -4, -6, and -7. BMP-2 and BMP-4 were significantly more common in acidic LPBs in comparison with neutral preparations. We also observed a considerable variation among platelet donors with respect to the release of BMPs at pH 4.3 and 7.4. In conclusion, a considerable variation was found among platelet donors, which may be of importance considering the ambiguous results previously reported on osteoblast proliferation and differentiation.

  2. 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

  3. 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

  4. Nanotechnology: Platelet mimicry

    NASA Astrophysics Data System (ADS)

    Farokhzad, Omid C.

    2015-10-01

    Cloaking drug-loaded nanoparticles with platelet membranes enhances the drugs' abilities to target desired cells and tissues. This technology might improve treatments for cardiovascular and infectious diseases. See Letter p.118

  5. Platelet-delivered therapeutics.

    PubMed

    Lyde, R; Sabatino, D; Sullivan, S K; Poncz, M

    2015-06-01

    We have proposed that modified platelets could potentially be used to correct intrinsic platelet defects as well as for targeted delivery of therapeutic molecules to sights of vascular injury. Ectopic expression of proteins within α-granules prior to platelet activation has been achieved for several proteins, including urokinase, factor (F) VIII, and partially for FIX. Potential uses of platelet-directed therapeutics will be discussed, focusing on targeted delivery of urokinase as a thromboprophylactic agent and FVIII for the treatment of hemophilia A patients with intractable inhibitors. This presentation will discuss new strategies that may be useful in the care of patients with vascular injury as well as remaining challenges and limitations of these approaches. PMID:26149015

  6. Platelet associated antibodies

    MedlinePlus

    ... of the following: For unknown reasons (idiopathic thrombocytopenic purpura, or ITP ) Side effect of certain drugs such ... 2012:chap 134. Read More Antibody Idiopathic thrombocytopenic purpura (ITP) Platelet count Serum globulin electrophoresis Thrombocytopenia Update ...

  7. 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

  8. 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

  9. Feasibility of a tandem photocatalytic oxidation-adsorption system for removal of monoaromatic compounds at concentrations in the sub-ppm-range.

    PubMed

    Jo, Wan-Kuen; Yang, Chang-Hee

    2009-09-01

    Unlike previous photocatalytic oxidation (PCO) studies incorporated with adsorption, this study investigates the feasibility of applying a tandem PCO-adsorption hybrid technique regarding low-level monoaromatic compound removal. The PCO efficiencies decreased as the hydraulic diameter (HD) increased. A PCO reactor of a medium HD size was selected for further experiments. Under conditions relevant to the use of the PCO system, the CO level measured during the PCO process was minimal in comparison to indoor CO levels. Trace level formations of formaldehyde and acetaldehyde were observed during the photocatalytic process, but these compounds were undetectable at the activated carbon unit outlet. The degradation efficiencies, obtained from the PCO unit, exhibited a dependence on both the inlet concentration (IC) and relative humidity (RH), whereas those from the PCO-adsorption hybrid system did not. Under specific conditions, the PCO unit presented a high degradation efficiency of close to, or exceeding 90%, in regards to ethyl benzene, o-xylene, and m,p-xylene. However, the benzene air concentrations, after being treated by the PCO unit, substantially exceeded the USEPA inhalation reference concentration guideline of 30microgm(-3) (corresponding to 0.01ppm). In contrast, the PCO-adsorption hybrid system presented a high removal efficiency of close to 100% regarding all compounds, regardless of the IC or RH range. Consequently, it is suggested that the PCO-adsorption hybrid system has a synergistic advantage of photocatalysis and adsorption in regards to the BTEX elimination process. PMID:19666187

  10. Platelets and diabetes mellitus.

    PubMed

    Santilli, Francesca; Simeone, Paola; Liani, Rossella; Davì, Giovanni

    2015-07-01

    Platelet activation plays a key role in atherothrombosis in type 2 diabetes mellitus (T2DM) and increased in vivo platelet activation with enhanced thromboxane (TX) biosynthesis has been reported in patients with impairment of glucose metabolism even in the earlier stages of disease and in the preclinical phases. In this regards, platelets appear as addresses and players carrying and transducing metabolic derangement into vascular injury. The present review critically addresses key pathophysiological aspects including (i) hyperglycemia, glycemic variability and insulin resistance as determinants and predictors of platelet activation, (ii) inflammatory mediators derived from platelets, such as soluble CD40 ligand, soluble CD36, Dickkopf-1 and probably soluble receptor for advanced glycation-end-products (sRAGE), which expand the functional repertoire of platelets from players of hemostasis and thrombosis to powerful amplifiers of inflammation by promoting the release of cytokines and chemokines, cell activation, and cell-cell interactions; (iii) molecular mechanisms underpinning the less-than-expected antithrombotic protection by aspirin (ASA), despite regular antiplatelet prophylaxis at the standard dosing regimen, and (iv) stratification of patients deserving different antiplatelet strategies, based on the metabolic phenotype. Taken together, these pathophysiological aspects may contribute to the development of promising mechanism-based therapeutic strategies to reduce the progression of atherothrombosis in diabetic subjects. PMID:25986598

  11. Feasibility of low-concentration iodinated contrast medium with lower-tube-voltage dual-source CT aortography using iterative reconstruction: comparison with automatic exposure control CT aortography.

    PubMed

    Shin, Hee Jeong; Kim, Song Soo; Lee, Jae-Hwan; Park, Jae-Hyeong; Jeong, Jin-Ok; Jin, Seon Ah; Shin, Byung Seok; Shin, Kyung-Sook; Ahn, Moonsang

    2016-06-01

    To evaluate the feasibility of low-concentration contrast medium (CM) for vascular enhancement, image quality, and radiation dose on computed tomography aortography (CTA) using a combined low-tube-voltage and iterative reconstruction (IR) technique. Ninety subjects underwent dual-source CT (DSCT) operating in dual-source, high-pitch mode. DSCT scans were performed using both high-concentration CM (Group A, n = 50; Iomeprol 400) and low-concentration CM (Group B, n = 40; Iodixanol 270). Group A was scanned using a reference tube potential of 120 kVp and 120 reference mAs under automatic exposure control with IR. Group B was scanned using low-tube-voltage (80 or 100 kVp if body mass index ≥25 kg/m(2)) at a fixed current of 150 mAs, along with IR. Images of the two groups were compared regarding attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), iodine load, and radiation dose in various locations of the CTA. In comparison between Group A and Group B, the average mean attenuation (454.73 ± 86.66 vs. 515.96 ± 101.55 HU), SNR (25.28 ± 4.34 vs. 31.29 ± 4.58), and CNR (21.83 ± 4.20 vs. 27.55 ± 4.81) on CTA in Group B showed significantly greater values and significantly lower image noise values (18.76 ± 2.19 vs. 17.48 ± 3.34) than those in Group A (all Ps < 0.05). Homogeneous contrast enhancement from the ascending thoracic aorta to the infrarenal abdominal aorta was significantly superior in Group B (P < 0.05). Low-concentration CM and a low-tube-voltage combination technique using IR is a feasible method, showing sufficient contrast enhancement and image quality. PMID:26621755

  12. Preservation of hemostatic and structural properties of rehydrated lyophilized platelets: potential for long-term storage of dried platelets for transfusion.

    PubMed

    Read, M S; Reddick, R L; Bode, A P; Bellinger, D A; Nichols, T C; Taylor, K; Smith, S V; McMahon, D K; Griggs, T R; Brinkhous, K M

    1995-01-17

    Currently, therapeutic platelet concentrates can be stored for only 5 days. We have developed a procedure that permits long-term storage of fixed and lyophilized platelets that retain hemostatic properties after rehydration. These rehydrated lyophilized platelets (RL platelets) restore hemostasis in thrombocytopenic rats and become incorporated in the hemostatic plug of bleeding time wounds of normal dogs as well as von Willebrand disease dogs with partially replenished plasma von Willebrand factor. Ultrastructurally, these platelets are well preserved and are comparable to control normal washed platelets. Flow cytometry analysis shows that RL platelets react with antibodies to the major surface receptors, glycoprotein (GP)Ib and GPIIb/IIIa. These receptors are involved in platelet agglutination, aggregation, and adhesion. In vitro functional tests document the ability of RL platelets to adhere to denuded subendothelium and to spread on a foreign surface. Circulating RL platelets participated in carotid arterial thrombus formation induced in normal canine subjects. The participation of RL platelets in these vital hemostatic properties suggests that with further development they could become a stable platelet product for transfusion. PMID:7831298

  13. Viability of platelets following storage in the irradiated state. A pair-controlled study

    SciTech Connect

    Read, E.J.; Kodis, C.; Carter, C.S.; Leitman, S.F.

    1988-09-01

    Gamma irradiation of blood products is a standard practice recommended for the prevention of posttransfusion graft-versus-host disease in susceptible hosts. We studied the effects of irradiation on stored platelet concentrates and evaluated whether platelets could be stored for 5 days in the irradiated state without adverse effects on their viability. Using a pair-controlled design in which each of six normal subjects acted as his or her own control, we compared in vitro storage characteristics and in vivo kinetics of platelet concentrates exposed to 30 Gy and stored for 5 days with those of platelet concentrates simply stored for 5 days without irradiation. Irradiation had no significant effects on in vitro storage characteristics (platelet count, mean platelet volume, pH, and white cell count) or on in vivo kinetics, including initial recovery and mean platelet survival. Using the multiple-hit model, initial recovery was 49.6 +/- 10.8 percent, and mean platelet survival was 5.6 +/- 1.05 days for irradiated concentrates, compared with 51.3 +/- 13.0 percent and 5.9 +/- 0.50 days, respectively, for the unirradiated control concentrates. We conclude that irradiation of platelet concentrates with up to 30 Gy has no effect on their in vivo recovery or survival, and that irradiation administered before storage of platelet concentrates does not interfere with their clinical efficacy.

  14. Amorphous silica nanoparticles aggregate human platelets: potential implications for vascular homeostasis

    PubMed Central

    Corbalan, J Jose; Medina, Carlos; Jacoby, Adam; Malinski, Tadeusz; Radomski, Marek W

    2012-01-01

    Background Amorphous silica nanoparticles (SiNP) can be used in medical technologies and other industries leading to human exposure. However, an increased number of studies indicate that this exposure may result in cardiovascular inflammation and damage. A high ratio of nitric oxide to peroxynitrite concentrations ([NO]/[ONOO−]) is crucial for cardiovascular homeostasis and platelet hemostasis. Therefore, we studied the influence of SiNP on the platelet [NO]/[ONOO−] balance and platelet aggregation. Methods Nanoparticle–platelet interaction was examined using transmission electron microscopy. Electrochemical nanosensors were used to measure the levels of NO and ONOO− released by platelets upon nanoparticle stimulation. Platelet aggregation was studied using light aggregometry, flow cytometry, and phase contrast microscopy. Results Amorphous SiNP induced NO release from platelets followed by a massive stimulation of ONOO− leading to an unfavorably low [NO]/[ONOO−] ratio. In addition, SiNP induced an upregulation of selectin P expression and glycoprotein IIb/IIIa activation on the platelet surface membrane, and led to platelet aggregation via adenosine diphosphate and matrix metalloproteinase 2-dependent mechanisms. Importantly, all the effects on platelet aggregation were inversely proportional to nanoparticle size. Conclusions The exposure of platelets to amorphous SiNP induces a critically low [NO]/[ONOO−] ratio leading to platelet aggregation. These findings provide new insights into the pharmacological profile of SiNP in platelets. PMID:22334785

  15. Clinical uses of radiolabeled platelets

    SciTech Connect

    Datz, F.L.; Christian, P.E.; Baker, W.J.

    1985-12-01

    Platelets were first successfully radiolabeled in 1953. At that time, investigators were primarily interested in developing a technique to accurately measure platelet life span in both normal and thrombocytopenic patients. Studies using platelets labeled with /sup 51/Cr have shown shortened platelet survival times in a number of diseases including idiopathic thrombocytopenic purpura, coronary artery disease, and diabetes mellitus. More recently, labels such as /sup 111/In have been developed that allow in vivo imaging of platelets. Indium-111 platelets are being used to better understand the pathophysiology of atherosclerosis, thrombophlebitis, pulmonary embolism and clotting disorders, and to improve the clinical diagnosis of these diseases.

  16. Akt signaling in platelets and thrombosis

    PubMed Central

    Woulfe, Donna S

    2010-01-01

    Akt is a Ser–Thr kinase with pleiotropic effects on cell survival, growth and metabolism. Recent evidence from gene-deletion studies in mice, and analysis of human platelets treated with Akt inhibitors, suggest that Akt regulates platelet activation, with potential consequences for thrombosis. Akt activation is regulated by the level of phosphoinositide 3-phosphates, and proteins that regulate concentrations of this lipid also regulate Akt activation and platelet function. Although the effectors through which Akt contributes to platelet activation are not definitively known, several candidates are discussed, including endothelial nitric oxide synthase, glycogen synthase kinase 3β, phosphodiesterase 3A and the integrin β3 tail. Selective inhibitors of Akt isoforms or of proteins that contribute to its activation, such as individual PI3K isoforms, may make attractive targets for antithrombotic therapy. This review summarizes the current literature describing Akt activity and its regulation in platelets, including speculation regarding the future of Akt or its regulatory pathways as targets for the development of antithrombotic therapies. PMID:20352060

  17. Calmodulin antagonists induce platelet apoptosis.

    PubMed

    Wang, Zhicheng; Li, Suping; Shi, Quanwei; Yan, Rong; Liu, Guanglei; Dai, Kesheng

    2010-04-01

    Calmodulin (CaM) antagonists induce apoptosis in various tumor models and inhibit tumor cell invasion and metastasis, thus some of which have been extensively used as anti-cancer agents. In platelets, CaM has been found to bind directly to the cytoplasmic domains of several platelet receptors. Incubation of platelets with CaM antagonists impairs the receptors-related platelet functions. However, it is still unknown whether CaM antagonists induce platelet apoptosis. Here we show that CaM antagonists N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W7), tamoxifen (TMX), and trifluoperazine (TFP) induce apoptotic events in human platelets, including depolarization of mitochondrial inner transmembrane potential, caspase-3 activation, and phosphatidylserine exposure. CaM antagonists did not incur platelet activation as detected by P-selectin surface expression and PAC-1 binding. However, ADP-, botrocetin-, and alpha-thrombin-induced platelet aggregation, platelet adhesion and spreading on von Willebrand factor surface were significantly reduced in platelets pre-treated with CaM antagonists. Furthermore, cytosolic Ca(2+) levels were obviously elevated by both W7 and TMX, and membrane-permeable Ca(2+) chelator BAPTA-AM significantly reduced apoptotic events in platelets induced by W7. Therefore, these findings indicate that CaM antagonists induce platelet apoptosis. The elevation of the cytosolic Ca(2+) levels may be involved in the regulation of CaM antagonists-induced platelet apoptosis. PMID:20172594

  18. Platelets and Infections – Complex Interactions with Bacteria

    PubMed Central

    Hamzeh-Cognasse, Hind; Damien, Pauline; Chabert, Adrien; Pozzetto, Bruno; Cognasse, Fabrice; Garraud, Olivier

    2015-01-01

    Platelets can be considered sentinels of vascular system due to their high number in the circulation and to the range of functional immunoreceptors they express. Platelets express a wide range of potential bacterial receptors, including complement receptors, FcγRII, Toll-like receptors but also integrins conventionally described in the hemostatic response, such as GPIIb–IIIa or GPIb. Bacteria bind these receptors either directly, or indirectly via fibrinogen, fibronectin, the first complement C1q, the von Willebrand Factor, etc. The fate of platelet-bound bacteria is questioned. Several studies reported the ability of activated platelets to internalize bacteria such as Staphylococcus aureus or Porphyromonas gingivalis, though there is no clue on what happens thereafter. Are they sheltered from the immune system in the cytoplasm of platelets or are they lysed? Indeed, while the presence of phagolysosome has not been demonstrated in platelets, they contain antimicrobial peptides that were shown to be efficient on S. aureus. Besides, the fact that bacteria can bind to platelets via receptors involved in hemostasis suggests that they may induce aggregation; this has indeed been described for Streptococcus sanguinis, S. epidermidis, or C. pneumoniae. On the other hand, platelets are able to display an inflammatory response to an infectious triggering. We, and others, have shown that platelet release soluble immunomodulatory factors upon stimulation by bacterial components. Moreover, interactions between bacteria and platelets are not limited to only these two partners. Indeed, platelets are also essential for the formation of neutrophil extracellular traps by neutrophils, resulting in bacterial clearance by trapping bacteria and concentrating antibacterial factors but in enhancing thrombosis. In conclusion, the platelet–bacteria interplay is a complex game; its fine analysis is complicated by the fact that the inflammatory component adds to the aggregation response

  19. Resistance of platelet proteins to effects of ionizing radiation

    SciTech Connect

    Prodouz, K.N.; Habraken, J.W.; Moroff, G. )

    1990-12-01

    Gamma irradiation of blood components prevents lymphocyte-induced graft-versus-host disease after transfusion in immunocompromised individuals. In this report we demonstrate the resistance of blood platelet proteins to gamma radiation-induced protein cleavage and aggregate formation when platelet concentrates were treated with a dose of 5000 rad. Results of one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total platelet protein and cytoskeletal protein preparations indicate that platelet proteins are neither cleaved nor cross-linked under these conditions of irradiation. These results support those of a previous study that documented the lack of any adverse effect of 5000 rad gamma radiation on in vitro platelet properties.

  20. Hydrogen platelets in crystalline silicon - Precursors for the "smart cut"

    SciTech Connect

    Reboredo, Fernando A; Pantelides, Sokrates T

    1999-01-01

    High concentrations of H in crystalline Si are known to induce planar defects (platelets), primarily in the (100) and the (Ill)planes. These platelets are precursors for the so-called "smart cut" technique for fabricating Silicon-On-insulator (SOI) structures. The atomic-scale mechanisms for the nucleation and growth of the H-induced platelets and many other experimental observations have remained elusive. We review recent extensive first-principles calculations in terms of which a comprehensive picture of platelet nucleation and growth has emerged. The theory naturally accounts for the observed preference for (111) and (100) planes, for H release and trapping of H-2 molecules, and other observations. The platelets are arrays of second-neighbor hydrogenated vacancies that do not bind to each other, but their formation is due to energetically preferred reaction pathways.

  1. [Platelets-rich plasma: a versatile tool for regenerative medicine?].

    PubMed

    Carrillo-Mora, Paul; González-Villalva, Adriana; Macías-Hernández, Salvador Israel; Villaseñor, Carlos Pineda

    2013-01-01

    Platelet-rich plasma is a blood product concentrate obtained by centrifugation of whole blood that is characterized by a high concentration of platelets (4 to 6 times their normal values). The high concentration of trophic factors contained in the granules of platelets, have led to suggest that the application of platelet-rich plasma can help to stimulate or accelerate the repair or regeneration of a number of tissues. Since their first application in the treatment of skin ulcers in 1980, a considerable number of novel applications in different fields of medicine have emerged (Ophthalmology, Otorhinolaryngology, Maxillofacial Surgery surgical wounds, musculoskeletal disorders, burns, Esthetic Surgery, repair of peripheral nerves, etc.), some of these applications with clearly positive or very promising results. Despite the large amount of experimental and clinical literature about the usefulness of platelet-rich plasma in different areas of regenerative medicine, there are few therapeutic indications in which it is fully demonstrated its effectiveness. This fact highlights the importance of carry out methodologically appropriate clinical trials in the near future, in order to improve the evidence level of platelet-rich plasma treatment. The purpose of this article is to perform an update and critical review about the biological basis of platelet-rich plasma, to review indications for which there is more scientific support on its use, and finally to describe their new indications that are currently under research. PMID:23461926

  2. In vitro effects of ethanol on the pathways of platelet aggregation

    SciTech Connect

    Rand, M.L.; Kinlough-Rathbone, R.L.; Packham, M.A.; Mustard, J.F.

    1986-03-01

    Ethanol is reported to inhibit platelet aggregation in vivo and in vitro, but the mechanisms of its action on stimulus-response coupling in platelets is unknown. Platelet aggregation to thrombin occurs through at least three pathways: released ADP; thromboxane A/sub 2/ (TXA/sub 2/); and a third pathway(s). Aggregation of rabbit platelets in citrated platelet-rich plasma (PRP) or washed suspensions to ADP (0.5-10 ..mu..M) was not affected by ethanol, at concentrations up to 5 mg/ml (lethal). Primary ADP-induced (5 ..mu..M) aggregation of human platelets in PRP was also unaffected by ethanol, but secondary aggregation and release of /sup 14/C-serotonin, due to TXA/sub 2/ formation, was inhibited by ethanol (2 and 4 mg/ml). Since arachidonate (AA)-induced (25-250 ..mu..M) aggregation and release by washed rabbit platelets was unaltered by ethanol, it may inhibit mobilization of AA from platelet membrane phospholipids. Ethanol (2-4 mg/ml) inhibited rabbit platelet aggregation and release to low concentrations of thrombin (< 10 mU/ml) or collagen, and also inhibited aggregation and release of aspirin-treated (500 ..mu.. M) rabbit platelets (that cannot form TXA/sub 2/) to low concentrations of thrombin (< 10 mU/ml). Thus, ethanol does not inhibit the mobilization of AA, and partially inhibits the third pathway(s) of platelet aggregation.

  3. Polyphosphate, Platelets, and Coagulation

    PubMed Central

    Travers, Richard J.; Smith, Stephanie A.; Morrissey, James H.

    2015-01-01

    While we have understood the basic outline of the enzymes and reactions that make up the traditional blood coagulation cascade for many years, recently our appreciation of the complexity of these interactions has greatly increased. This has resulted in unofficial “revisions” of the coagulation cascade to include new amplification pathways and connections between the standard coagulation cascade enzymes, as well as the identification of extensive connections between the immune system and the coagulation cascade. The discovery that polyphosphate is stored in platelet dense granules and is secreted during platelet activation has resulted in a recent burst of interest in the role of this ancient molecule in human biology. Here we review the increasingly complex role of platelet polyphosphate in hemostasis, thrombosis, and inflammation that has been uncovered in recent years, as well as novel therapeutics centered on modulating polyphosphate’s roles in coagulation and inflammation. PMID:25976958

  4. 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

  5. Development of the platelet micro-orifice injector. [for liquid propellant rocket engines

    NASA Technical Reports Server (NTRS)

    La Botz, R. J.

    1984-01-01

    For some time to come, liquid rocket engines will continue to provide the primary means of propulsion for space transportation. The injector represents a key to the optimization of engine and system performance. The present investigation is concerned with a unique injector design and fabrication process which has demonstrated performance capabilities beyond that achieved with more conventional approaches. This process, which is called the 'platelet process', makes it feasible to fabricate injectors with a pattern an order of magnitude finer than that obtainable by drilling. The fine pattern leads to an achievement of high combustion efficiencies. Platelet injectors have been identified as one of the significant technology advances contributing to the feasibility of advanced dual-fuel booster engines. Platelet injectors are employed in the Space Shuttle Orbit Maneuvering System (OMS) engines. Attention is given to injector design theory as it relates to pattern fineness, a description of platelet injectors, and test data obtained with three different platelet injectors.

  6. An Assay of Measuring Platelet Reactivity Using Monoclonal Antibody against Activated Platelet Glycoprotein IIb/IIIa in Patients Taking Clopidogrel

    PubMed Central

    Choi, Joon-Hyouk; Kim, Song-Yi; Kim, Ki-Seok; Kim, Young Ree; Kang, Sung Ha

    2015-01-01

    Background and Objectives Residual platelet reactivity in patients who are taking clopidogrel is commonly measured with VerifyNow assay, which is based on the principle of light transmission aggregometry. However, to evaluate the residual platelet reactivity, it would be more accurate if the reactivity of platelet glycoprotein (GP) IIb/IIIa is directly monitored. In this study, PAC1, a monoclonal antibody against activated platelet GP IIb/IIIa, was used to measure the residual platelet reactivity. Subjects and Methods Twenty seven patients with coronary artery disease taking clopidogrel were enrolled. Platelets in whole blood were stained with fluorescein isothiocyanate (FITC)-conjugated PAC1. Mean fluorescence intensity (MFI) and % positive platelets (PP) were measured with flow cytometry, and the binding index (BI; MFI × %PP/100) was calculated. P2Y12 reaction unit (PRU) and % inhibition of VerifyNow assay were also measured in the usual manner. Results PRU of VerifyNow assay correlated significantly with MFI, %PP, and BI at 10 µM (r=0.59, 0.73, and 0.60, respectively, all p<0.005) and 20 µM of adenosine diphosphate (ADP; r=0.61, 0.75, and 0.63, respectively, all p<0.005). The % inhibition also correlated significantly with MFI, %PP, and BI at 10 µM (r=-0.60, -0.69, and -0.59, respectively, all p<0.005) and 20 µM of ADP (r=-0.63, -0.71, and -0.62, respectively, all p<0.005). Conclusion Direct measurements of the reactivity of platelet GP IIb/IIIa were feasible using PAC1 and flow cytometry in patients taking clopidogrel. Further clinical studies are required to determine the cut-off values which would define high residual platelet reactivity in patients on this treatment protocol. PMID:26413105

  7. Pneumolysin Mediates Platelet Activation In Vitro.

    PubMed

    Nel, Jan Gert; Durandt, Chrisna; Mitchell, Timothy J; Feldman, Charles; Anderson, Ronald; Tintinger, Gregory R

    2016-08-01

    This study has explored the role of the pneumococcal toxin, pneumolysin (Ply), in activating human platelets. Following exposure to Ply (10-80 ng/ml), platelet activation and cytosolic Ca(2+) concentrations were measured flow cytometrically according to the level of expression of CD62P (P-selectin) and spectrofluorimetrically, respectively. Exposure to Ply resulted in marked upregulation of expression of platelet CD62P, achieving statistical significance at concentrations of 40 ng/ml and higher (P < 0.05), in the setting of increased influx of Ca(2+). These potentially pro-thrombotic actions of Ply were attenuated by depletion of Ca(2+) from the extracellular medium or by exposure of the cells to a pneumolysoid devoid of pore-forming activity. These findings are consistent with a mechanism of Ply-mediated platelet activation involving sub-lytic pore formation, Ca(2+) influx, and mobilization of CD62P-expressing α-granules, which, if operative in vivo, may contribute to the pathogenesis of associated acute lung and myocardial injury during invasive pneumococcal disease. PMID:27192991

  8. Imaging of platelets in right-sided extracardiac conduits in humans

    SciTech Connect

    Agarwal, K.C.; Wahner, H.W.; Dewanjee, M.K.; Fuster, V.; Puga, F.J.; Danielson, G.K.; Chesebro, J.H.; Feldt, R.H.

    1982-04-01

    As a connection between the systemic venous ventricle and the pulmonary artery, valved Dacron extracardiac conduits have remarkably influenced the surgical approach to many complex congenital heart defects. Obstruction of the conduit, however, can reduce the long-term effectiveness of this corrective procedure. In addition to stenosis of the porcine valve, formation of thick fibrous neointima plays a major role in the pathogenesis of conduit obstruction. The purpose of this study was to determine whether platelet deposition could be demonstrated in these conduits by external imaging with In-111-labeled autologous platelets. After injection of labeled platelets either immediately after operation or on the fifth to eighth post-operative day, imaging was performed by standard procedures. Eight of nine patients had platelet accumulation in the conduit, and treatment with aspirin and dipyridamole caused no recognizable change in platelet deposition. This study demonstrates the feasibility of imaging platelet deposition in Dacron conduits and shows that the pattern of deposition varies with time.

  9. Imaging of platelets in right-sided extracardiac conduits in humans

    SciTech Connect

    Agarwal, K.C.; Wahner, H.W.; Dewanjee, M.K.; Fuster, V.; Puga, F.J.; Danielson, G.K.; Chesebro, J.H.; Feldt, R.H.

    1982-04-01

    As a connection between the systemic venous ventricle and the pulmonary artery, valved Dacron extracardiac conduits have remarkably influenced the surgical approach to many complex congenital heart defects. Obstruction of the conduit, however, can reduce the long-term effectiveness of this corrective procedure. In addition to stenosis of the porcine valve, formation of thick fibrous neointima plays a major role in the pathogenesis of conduit obstruction. The purpose of this study was to determine whether platelet deposition could be demonstrated in these conduits by external imaging with /sup 111/In-labeled autologous platelets. After injection of labeled platelets either immediately after operation or on the fifth to eighth postoperative day, imaging was performed by standard procedures. Eight of nine patients had platelet accumulation in the conduit, and treatment with aspirin and dipyridamole caused no recognizable change in platelet deposition. This study demonstrates the feasibility of imaging platelet deposition in Dacron conduits and shows that the pattern of deposition varies with time.

  10. Effects of platelet inhibitors on propyl gallate-induced platelet aggregation, protein tyrosine phosphorylation, and platelet factor 3 activation.

    PubMed

    Xiao, Hongyan; Kovics, Richard; Jackson, Van; Remick, Daniel G

    2004-04-01

    Propyl gallate (PG) is a platelet agonist characterized by inducing platelet aggregation, protein tyrosine phosphorylation, and platelet factor 3 activity. The mechanisms of platelet activation following PG stimulation were examined by pre-incubating platelets with well-defined platelet inhibitors using platelet aggregation, protein tyrosine phosphorylation, activated plasma clotting time, and annexin V binding by flow cytometry. PG-induced platelet aggregation and tyrosine phosphorylation of multiple proteins were substantially abolished by aspirin, apyrase, and abciximab (c7E3), suggesting that PG is associated with activation of platelet cyclooxygenase 1, adenosine phosphate receptors, and glycoprotein IIb/IIIa, respectively. The phosphorylation of the cytoskeletal enzyme pp60(c-src) increased following PG stimulation, but was blunted by pre-incubation of platelets with aspirin, apyrase, and c7E3, suggesting that tyrosine kinase is important for the signal transduction of platelet aggregation. Propyl gallate also activates platelet factor 3 by decreasing the platelet coagulation time and increasing platelet annexin V binding. Platelet incubation with aspirin, apyrase, and c7E3 did not alter PG-induced platelet coagulation and annexin V binding. The results suggest that platelet factor 3 activation and membrane phosphotidylserine expression were not involved with activation of platelet cyclooxygenase, adenosine phosphate receptors, and glycoprotein IIb/IIIa. PG is unique in its ability to stimulate platelet aggregation and coagulation simultaneously, and platelet inhibitors in this study affect only platelet aggregation but not platelet coagulation. PMID:15060414

  11. 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

  12. Feasibility study on 1.6 μm continuous-wave modulation laser absorption spectrometer system for measurement of global CO2 concentration from a satellite.

    PubMed

    Kameyama, Shumpei; Imaki, Masaharu; Hirano, Yoshihito; Ueno, Shinichi; Kawakami, Shuji; Sakaizawa, Daisuke; Kimura, Toshiyoshi; Nakajima, Masakatsu

    2011-05-10

    A feasibility study is carried out on a 1.6 μm continuous-wave modulation laser absorption spectrometer system for measurement of global CO(2)concentration from a satellite. The studies are performed for wavelength selection and both systematic and random error analyses. The systematic error in the differential absorption optical depth (DAOD) is mainly caused by the temperature estimation error, surface pressure estimation error, altitude estimation error, and ON wavelength instability. The systematic errors caused by unwanted backscattering from background aerosols and dust aerosols can be reduced to less than 0.26% by using a modulation frequency of around 200 kHz, when backscatter coefficients of these unwanted backscattering have a simple profile on altitude. The influence of backscattering from cirrus clouds is much larger than that of dust aerosols. The transmission power required to reduce the random error in the DAOD to 0.26% is determined by the signal-to-noise ratio and the carrier-to-noise ratio calculations. For a satellite altitude of 400 km and receiving aperture diameter of 1 m, the required transmission power is approximately 18 W and 70 W when albedo is 0.31 and 0.08, respectively; the total measurement time in this case is 4 s, which corresponds to a horizontal resolution of 28 km. PMID:21556107

  13. Feasibility of interstitial near-infrared radiance spectroscopy platform for ex vivo canine prostate studies: optical properties extraction, hemoglobin and water concentration, and gold nanoparticles detection.

    PubMed

    Grabtchak, Serge; Montgomery, Logan G; Whelan, William M

    2014-05-01

    The canine prostate is a close match for the human prostate and is used in research of prostate cancers. Determining accurately optical absorption and scattering properties of the gland in a wide spectral range (preferably in a minimally invasive way), linking optical properties to concentrations of major endogenous chromophores, and detecting the presence of localized optical inhomogeneities like inclusions of gold nanoparticles for therapeutic and diagnostic purposes, are among the major challenges for researchers. The goal of the article is to demonstrate a feasibility of the multifunctional radiance spectroscopy platform in providing the required information. For ex vivo canine prostate, extraction of the effective attenuation and diffusion coefficients using relative cw radiance measurements was demonstrated in the 650- to 900-nm range. The derived absorption coefficient was decomposed to contributions from 9.0 μM HbO₂, 29.6 μM Hb, and 0.47 fractional volume of H₂O. Detection of a localized inclusion containing ∼1.5·1010 gold nanorods (0.8 μg Au) at 10 mm distance from the urethra was achieved with the detector in the urethra and the light source in a virtual rectum position. The platform offers the framework for a systematic study of various chromophores in the prostate that can be used as comprehensive diagnostic markers. PMID:24788374

  14. Feasibility of interstitial near-infrared radiance spectroscopy platform for ex vivo canine prostate studies: optical properties extraction, hemoglobin and water concentration, and gold nanoparticles detection

    NASA Astrophysics Data System (ADS)

    Grabtchak, Serge; Montgomery, Logan G.; Whelan, William M.

    2014-05-01

    The canine prostate is a close match for the human prostate and is used in research of prostate cancers. Determining accurately optical absorption and scattering properties of the gland in a wide spectral range (preferably in a minimally invasive way), linking optical properties to concentrations of major endogenous chromophores, and detecting the presence of localized optical inhomogeneities like inclusions of gold nanoparticles for therapeutic and diagnostic purposes, are among the major challenges for researchers. The goal of the article is to demonstrate a feasibility of the multifunctional radiance spectroscopy platform in providing the required information. For ex vivo canine prostate, extraction of the effective attenuation and diffusion coefficients using relative cw radiance measurements was demonstrated in the 650- to 900-nm range. The derived absorption coefficient was decomposed to contributions from 9.0 μM HbO2, 29.6 μM Hb, and 0.47 fractional volume of H2O. Detection of a localized inclusion containing ˜1.5.1010 gold nanorods (0.8 μg Au) at 10 mm distance from the urethra was achieved with the detector in the urethra and the light source in a virtual rectum position. The platform offers the framework for a systematic study of various chromophores in the prostate that can be used as comprehensive diagnostic markers.

  15. Platelet transport in microchannels

    NASA Astrophysics Data System (ADS)

    Reyssat, Mathilde; Le Goff, Anne; Blin, Antoine; Pujos, Justine; Magniez, Aurélie; Baruch, Dominique

    2013-11-01

    Blood platelets are small enucleated cells responsible for the arrest of bleeding. These cells have the ability to tether and translocate on injured vascular endothelium, thanks to a specific interaction between a receptor of their membrane and a protein expressed by the cells composing the inner wall of the vessel, the von Willebrand factor (VWF). Others cells have such abilities of rolling. Leucocytes, for example, translocate on surface due to a specific interaction between selectin molecules and their respective glycoprotein ligands. These kinds of cells present two modes of transport: they can either be advected by the flux, or translocate on surfaces due to specific ligand-receptor interactions. Our work consists first in studying experimentally the transport of platelets along a microchannel and then in modeling this particular cell transport. Due to these two modes of transport along a channel, platelets adhering to the surface are not equally distributed along the channel axis. We describe the evolution of the density of platelets with time and distance.

  16. Pravastatin and C reactive protein modulate protease- activated receptor-1 expression in vitro blood platelets.

    PubMed

    Chu, L-X; Zhou, S-X; Yang, F; Qin, Y-Q; Liang, Z-S; Mo, C-G; Wang, X-D; Xie, J; He, L-P

    2016-01-01

    Protease-activated receptor-1 (PAR-1) plays an important role in mediating activation of human platelets by thrombin. However, mechanism of statin in ADP-induced platelet PAR-1 expression is also unknown. Aggregometry, flow cytometry, immunoblotting and ELISA were used to determine role of pravastatin participating in ADP-induced platelet activation and PAR-1 expression. ADP stimulation significantly increased PAR-1 expression on platelets. PAR-1 antagonist SCH-79797 inhibited platelet aggregation as well as decreased platelet P-selectin expression induced by ADP. CRP inhibited PAR-1 expression induced by ADP in a concentration-dependent manner. Pravastatin treatment reduced PAR-1 expression in a concentration-dependent manner. Combination treatment of CRP and Pravastatin significantly reduced platelet PAR-1 expression induced by ADP. By western-blot analysis, pravastatin treatment did not influence total PAR-1 after ADP treatment. CRP decreased platelet total PAR-1 expression induced by ADP. Pravastatin and CRP reduced TXB2 formation by ADP significantly. CRP decreased thrombin fragment F1+2 level with ADP treatment. Pravastatin, in contrast, did not influence F1+2 level. Upon treatment with Pravastatin reduced platelet LOX-1 expression induced by ADP. In conclusion, PAR-1 served as a critical mechanism to relay platelet activation process induced by ADP. CRP and pravastatin reduce PAR-1 expression in platelet by ADP pathway. PMID:26950455

  17. Characterizing the modification of surface proteins with poly(ethylene glycol) to interrupt platelet adhesion

    PubMed Central

    Xu, Haiyan; Kaar, Joel L.; Russell, Alan J.; Wagner, William R.

    2010-01-01

    Surface protein modification with poly(ethylene glycol) (PEG) can inhibit acute thrombosis on damaged vascular and biomaterial surfaces by blocking surface protein–platelet interactions. However, the feasibility of employing protein reactive PEGs to limit intravascular and biomaterial thrombosis in vivo is contingent upon rapid and extensive surface protein modification. To characterize the factors controlling this potential therapeutic approach, the model protein bovine serum albumin was adsorbed onto polyurethane surfaces and modified with PEG-carboxymethyl succinimidyl ester (PEG-NHS), PEG-isocyanate (PEG-ISO), or PEG-diisocyanate (PEG-DISO) in aqueous buffer at varying concentrations and contact times. It was found that up to 5 PEGs could be attached per albumin molecule within one min and that adsorbed albumin PEGylation approached maximal levels by 6 min. The lability of reactive PEGs in aqueous buffer reduced total protein modification by 50% when the PEG solution was incubated for 7 min prior to application. For fibrinogen PEGylation (performed in the solution phase), PEG-NHS was more reactive than PEG-ISO or PEG-DISO. The γ peptide of fibrinogen, which contains several key platelet-binding motifs, was highly modified. A marked reduction in platelet adhesion was observed on fibrinogen-adsorbed polyurethane treated with PEG-NHS or PEG-DISO. Relative differences in platelet adhesion on PEG-NHS and PEG-DISO modified surfaces could be attributed to differences in reactivity towards fibrinogen and the size of the polymer backbone. Taken together, these findings provide insight and guidance for applying protein reactive PEGs for the interruption of acute thrombotic deposition. PMID:16457880

  18. Studies of activated GPIIb/IIIa receptors on the luminal surface of adherent platelets. Paradoxical loss of luminal receptors when platelets adhere to high density fibrinogen.

    PubMed Central

    Coller, B S; Kutok, J L; Scudder, L E; Galanakis, D K; West, S M; Rudomen, G S; Springer, K T

    1993-01-01

    The accessibility of activated GPIIb/IIIa receptors on the luminal surface of platelets adherent to damaged blood vessels or atherosclerotic plaques is likely to play a crucial role in subsequent platelet recruitment. To define better the factors involved in this process, we developed a functional assay to assess the presence of activated, luminal GPIIb/IIIa receptors, based on their ability to bind erythrocytes containing a high density of covalently coupled RGD-containing peptides (thromboerythrocytes). Platelets readily adhered to wells coated with purified type I rat skin collagen and the adherent platelets bound a dense lawn of thromboerythrocytes. With fibrinogen-coated wells, platelet adhesion increased as the fibrinogen-coating concentration increased, reaching a plateau at about 11 micrograms/ml. Thromboerythrocyte binding to the platelets adherent to fibrinogen showed a paradoxical response, increasing at fibrinogen coating concentrations up to approximately 4-6 micrograms/ml and then dramatically decreasing at higher fibrinogen-coating concentrations. Scanning electron microscopy demonstrated that the morphology of platelets adherent to collagen was similar to that of platelets adherent to low density fibrinogen, with extensive filopodia formation and ruffling. In contrast, platelets adherent to high density fibrinogen showed a bland, flattened appearance. Immunogold staining of GPIIb/IIIa receptors demonstrated concentration of the receptors on the filopodia, and depletion of receptors on the flattened portion of the platelets. Thus, there is a paradoxical loss of accessible, activated GPIIb/IIIa receptors on the luminal surface of platelets adherent to high density fibrinogen. Two factors may contribute to this result: engagement of GPIIb/IIIa receptors with fibrinogen on the abluminal surface leading to the loss of luminal receptors, and loss of luminal filopodia that interact with thromboerythrocytes. These data provide insight into the differences

  19. Platelet and coagulation factors in proliferative diabetic retinopathy.

    PubMed Central

    Borsey, D Q; Prowse, C V; Gray, R S; Dawes, J; James, K; Elton, R A; Clarke, B F

    1984-01-01

    Plasma beta-thromboglobulin, platelet factor 4, fibrinogen, fibrinopeptide A, antithrombin III, factor VIII related antigen, alpha 2-macroglobulin, platelet count, and total glycosylated haemoglobin were measured in three well matched groups of subjects: non-diabetic controls, diabetics without retinopathy, and diabetics with proliferative retinopathy. beta-thromboglobulin and platelet factor 4 concentrations were significantly higher in the diabetics with retinopathy than in the controls and platelet factor 4 was also increased in the diabetics without retinopathy compared with controls. Fibrinogen concentration was raised in diabetics without retinopathy compared with controls, diabetics with retinopathy compared with controls, and diabetics with retinopathy compared with those without. Fibrinopeptide A concentration did not differ significantly between groups. Antithrombin III levels were increased in diabetics with retinopathy compared with controls, and in diabetics with retinopathy compared with those without. Factor VIII related antigen values were higher in both the diabetic groups when compared with the controls. Fibrinopeptide A concentration correlated with both beta-thromboglobulin and platelet factor 4 in each of the three groups. Haemostatic abnormalities in diabetes have been shown, although a hypercoagulable state has not been confirmed. These changes in platelet and coagulation function may be secondary to the development of microvascular disease and their role in the pathogenesis of retinopathy remains uncertain. PMID:6202721

  20. 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

  1. The influence of organic peroxides on platelet aggregation and sensitivity to nitric oxide.

    PubMed

    Naseem, K M; Bruckdorfer, K R

    1999-01-01

    The effects of oxidative stress, induced by water-soluble and lipid peroxides, on platelet reactivity and platelet sensitivity to nitric oxide were investigated. Hydrogen peroxide and cumene hydroperoxide potentiated thrombin-induced platelet aggregation. In contrast, 15(S)-hydroperoxyeicosatetraenoic acid had no such effect, while 12(S)-hydroperoxyeicosatetraenoic acid inhibited platelet reactivity. All of the peroxides tested were found to decrease platelet sensitivity to nitric oxide, although the mechanisms by which the various peroxides altered platelet sensitivity to nitric oxide were different. The water-soluble peroxides opposed the actions of nitric oxide without affecting cyclic GMP levels, while 15(S)-hydroperoxyeicosatetraenoic acid caused a significant reduction in the concentration of cyclic GMP formed in response to NO. The data from this study demonstrate that water-soluble and lipid peroxides both affect platelet reactivity and regulation, but by different mechanisms. Thus, caution should be exercised when selecting peroxides to be used as models of oxidative stress. PMID:16801085

  2. Impaired platelet activation and cAMP homeostasis in MRP4-deficient mice

    PubMed Central

    Decouture, Benoit; Dreano, Elise; Belleville-Rolland, Tiphaine; Kuci, Orjeta; Dizier, Blandine; Bazaa, Amine; Coqueran, Bérard; Lompre, Anne-Marie; Denis, Cécile V.; Hulot, Jean-Sébastien; Gaussem, Pascale

    2015-01-01

    Molecules that reduce the level of cyclic adenosine 5′-monophosphate (cAMP) in the platelet cytosol, such as adenosine 5′-diphosphate (ADP) secreted from dense granules, trigger platelet activation. Therefore, any change in the distribution and/or availability of cyclic nucleotides or ADP may interfere with platelet reactivity. In this study, we evaluated the role of multidrug resistance protein 4 (MRP4, or ABCC4), a nucleotide transporter, in platelet functions in vivo and in vitro by investigating MRP4-deficient mice. MRP4 deletion resulted in a slight increase in platelet count but had no impact on platelet ultrastructure. In MRP4-deficient mice, the arterial occlusion was delayed and the tail bleeding time was prolonged. In a model of platelet depletion and transfusion mimicking a platelet-specific knockout, mice injected with MRP4−/− platelets also showed a significant increase in blood loss compared with mice injected with wild-type platelets. Defective thrombus formation and platelet activation were confirmed in vitro by studying platelet adhesion to collagen in flow conditions, integrin αIIbβ3 activation, washed platelet secretion, and aggregation induced by low concentrations of proteinase-activated receptor 4–activating peptide, U46619, or ADP. We found no role of MRP4 in ADP dense-granule storage, but MRP4 redistributed cAMP from the cytosol to dense granules, as confirmed by increased vasodilator-stimulated phosphoprotein phosphorylation in MRP4-deficient platelets. These data suggest that MRP4 promotes platelet aggregation by modulating the cAMP–protein kinase A signaling pathway, suggesting that MRP4 might serve as a target for novel antiplatelet agents. PMID:26316625

  3. Citrate bridges between mineral platelets in bone.

    PubMed

    Davies, Erika; Müller, Karin H; Wong, Wai Ching; Pickard, Chris J; Reid, David G; Skepper, Jeremy N; Duer, Melinda J

    2014-04-01

    We provide evidence that citrate anions bridge between mineral platelets in bone and hypothesize that their presence acts to maintain separate platelets with disordered regions between them rather than gradual transformations into larger, more ordered blocks of mineral. To assess this hypothesis, we take as a model for a citrate bridging between layers of calcium phosphate mineral a double salt octacalcium phosphate citrate (OCP-citrate). We use a combination of multinuclear solid-state NMR spectroscopy, powder X-ray diffraction, and first principles electronic structure calculations to propose a quantitative structure for this material, in which citrate anions reside in a hydrated layer, bridging between apatitic layers. To assess the relevance of such a structure in native bone mineral, we present for the first time, to our knowledge, (17)O NMR data on bone and compare them with (17)O NMR data for OCP-citrate and other calcium phosphate minerals relevant to bone. The proposed structural model that we deduce from this work for bone mineral is a layered structure with thin apatitic platelets sandwiched between OCP-citrate-like hydrated layers. Such a structure can explain a number of known structural features of bone mineral: the thin, plate-like morphology of mature bone mineral crystals, the presence of significant quantities of strongly bound water molecules, and the relatively high concentration of hydrogen phosphate as well as the maintenance of a disordered region between mineral platelets. PMID:24706850

  4. Epithelial sodium channel modulates platelet collagen activation.

    PubMed

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Alonso-Rangel, Lea; Benítez-Cardoza, Claudia; Ortega, Arturo

    2014-03-01

    Activated platelets adhere to the exposed subendothelial extracellular matrix and undergo a rapid cytoskeletal rearrangement resulting in shape change and release of their intracellular dense and alpha granule contents to avoid hemorrhage. A central step in this process is the elevation of the intracellular Ca(2+) concentration through its release from intracellular stores and on throughout its influx from the extracellular space. The Epithelial sodium channel (ENaC) is a highly selective Na(+) channel involved in mechanosensation, nociception, fluid volume homeostasis, and control of arterial blood pressure. The present study describes the expression, distribution, and participation of ENaC in platelet migration and granule secretion using pharmacological inhibition with amiloride. Our biochemical and confocal analysis in suspended and adhered platelets suggests that ENaC is associated with Intermediate filaments (IF) and with Dystrophin-associated proteins (DAP) via α-syntrophin and β-dystroglycan. Migration assays, quantification of soluble P-selectin, and serotonin release suggest that ENaC is dispensable for migration and alpha and dense granule secretion, whereas Na(+) influx through this channel is fundamental for platelet collagen activation. PMID:24679405

  5. Platelet satellitism: an ultrastructural study.

    PubMed Central

    Payne, C. M.

    1981-01-01

    The ultrastructural morphology of platelet-polymorph (platelet-polymorphonuclear leukocyte) rosettes was investigated in EDTA-anticoagulated blood obtained from two patients who exhibited the phenomenon of platelet satellitism. Most of the platelet profiles were attached to the polymorph surface by broad areas of contact. Examination of these broad areas of contact at high magnification revealed an intercellular material of low electron density. This material appeared to form strands, which bridged the intercellular space and spanned the entire area formed by the apposing plasma membranes. Phagocytosis of entire platelets was only observed in 1 case. The platelet profiles that participated in rosette formation revealed a large number of glycogen particles, compared with unattached platelets. Ultrastructural examination of "stress" platelets obtained from five normal subjects treated with steroids similarly showed a large number of glycogen particles, although no rosette formation or phagocytosis of platelets was observed. The etiology of platelet satellitism is discussed. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7223859

  6. 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

  7. Plasma Components and Platelet Activation Are Essential for the Antimicrobial Properties of Autologous Platelet-Rich Plasma: An In Vitro Study

    PubMed Central

    Drago, Lorenzo; Bortolin, Monica; Vassena, Christian; Romanò, Carlo L.; Taschieri, Silvio; Fabbro, Massimo Del

    2014-01-01

    Autologous platelet concentrates are successfully adopted in a variety of medical fields to stimulate bone and soft tissue regeneration. The rationale for their use consists in the delivery of a wide range of platelet-derived bioactive molecules that promotes wound healing. In addition, antimicrobial properties of platelet concentrates have been pointed out. In this study, the effect of the platelet concentration, of the activation step and of the presence of plasmatic components on the antimicrobial activity of pure platelet-rich plasma was investigated against gram positive bacteria isolated from oral cavity. The antibacterial activity, evaluated as the minimum inhibitory concentration, was determined through the microdilution two-fold serial method. Results seem to suggest that the antimicrobial activity of platelet-rich plasma against Enterococcus faecalis, Streptococcus agalactiae, Streptococcus oralis and Staphylococcus aureus is sustained by a co-operation between plasma components and platelet-derived factors and that the activation of coagulation is a fundamental step. The findings of this study may have practical implications in the modality of application of platelet concentrates. PMID:25232963

  8. Phase behavior of mixtures of colloidal platelets and nonadsorbing polymers

    NASA Astrophysics Data System (ADS)

    Zhang, Shu-Dong; Reynolds, Paul A.; van Duijneveldt, Jeroen S.

    2002-12-01

    The phase behavior of a model system of colloidal platelets and nonadsorbing polymers is studied using computer simulations and perturbation theory. The equation of state for the pure platelet reference system is obtained by Monte Carlo simulations, and the free volume fraction accessible to polymers is measured by a trial insertion method. The free volume fraction is also calculated using scaled particle theory. Subsequently, the phase diagram for platelet-polymer mixtures is calculated. For a platelet aspect ratio L/D=0.1 and a polymer to platelet size ratio d/D>0.2, we observe coexistence between two isotropic phases with different densities. For smaller polymers d/D<0.2, only one isotropic phase is present. At higher platelet concentrations nematic and columnar phases are found. Where possible, direct simulations of plate-polymer mixtures, namely Gibbs ensemble simulation and Gibbs-Duhem integration, are used to check the validity of the perturbation approach. Qualitatively similar results are obtained for platelets of L/D=0.05. The results are compared with existing theoretical data as well as with experimental observations.

  9. Biochemical and biophysical aspects of human platelet adhesion to collagen fibers

    PubMed Central

    Lyman, Bruce; Rosenberg, Lawrence; Karpatkin, Simon

    1971-01-01

    A method has been developed for measuring the adhesion of platelets to purified collagen fibers obtained from bovine tendon. This method differs from others in that: (a) platelet adhesion is measured in the absence of platelet aggregation; (b) platelet-rich plasma collected in ACD (acid citrate dextrose) or EDTA, or washed platelets can be employed; (c) adherent platelets are enumerated directly; (d) erythrocytes and leukocytes do not adhere. Washed platelets suspended in human Ringer solution exhibit negligible adhesion (at the platelet concentrations employed) in contrast to washed platelets suspended in plasma. Addition of purified human fibrinogen (95% clottable, 2-4 mg/ml) to human Ringer solution completely restores the ability of washed platelets to adhere to collagen fibers. Albumin (fatty acid free, 50 mg/ml) is also capable of restoring adhesion. Albumin and seven other proteins at concentrations of 5-10 mg/ml, with varying molecular weights, isoelectric points, and frictional coefficients are incapable of supporting the adhesion of washed platelets. The proteins tested were human globulin, hexokinase, hemoglobin, cytochrome-C, insulin, thyroglobulin, and muramidase. Platelet adhesion is proportional to both platelet concentration and fibrinogen concentration, but is independent of temperature or glycogen stores. Modification of fibrinogen by acylation of amino groups or removal of sialic acid has no effect on its ability to support platelet adhesion. Degradation of fibrinogen with purified plasmin results in decreased support of platelet adhesion. This accompanied formation of early breakdown products with clottability ranging from 84-0%. Formation of fibrinogen degradation products was monitored by SDS-polyacrylamide gel electrophoresis of the corresponding fibrins after reduction of disulfide bonds (a method capable of distinguishing α-, β- and gamma-chains). Decreased support of platelet adhesion is associated with the disappearance of intact

  10. Reduced serum inhibition of platelet-activating factor activity in preeclampsia.

    PubMed

    Benedetto, C; Massobrio, M; Bertini, E; Abbondanza, M; Enrieu, N; Tetta, C

    1989-01-01

    We determined in normal nonpregnant (group 1) women, normal pregnant (group 2) women, and patients with preeclampsia (group 3) the serum inhibition of platelet-activating factor activity, the presence of detectable amounts of platelet-activating factor in the blood, and platelet responsiveness in vitro to platelet-activating factor, and to other agonists (adenosine diphosphate, collagen, and ristocetin), and prostacyclin (prostaglandin I2). In patients with preeclampsia (group 3) the serum inhibition of platelet-activating factor activity was significantly lower than that in groups 1 and 2. However, no detectable amounts of platelet-activating factor were observed. The mean values of platelet aggregation induced by platelet-activating factor, adenosine diphosphate, collagen and ristocetin, and the prostaglandin I2-inhibitory concentration of 50% which is inversely correlated with platelet sensitivity to prostaglandin I2, were not significantly different between groups 2 and 3. It is suggested that in preeclampsia the defect in serum inhibitory potential of platelet-activating factor--induced platelet aggregation may contribute to the disturbance in the homeostatic balance between proaggregant and antiaggregant substances. PMID:2912073

  11. 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

  12. 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

  13. Human platelet lysate as a promising growth-stimulating additive for culturing of stem cells and other cell types.

    PubMed

    Shanskii, Ya D; Sergeeva, N S; Sviridova, I K; Kirakozov, M S; Kirsanova, V A; Akhmedova, S A; Antokhin, A I; Chissov, V I

    2013-11-01

    We compared the composition and biological activity of fetal calf serum and platelet lysate from donor platelet concentrate. In platelet lysate, the concentrations of alkaline phosphatase, lactate dehydrogenase, creatinine, and mineral metabolism parameters were lower, while parameters of lipid and protein metabolism were higher than in fetal calf serum. The concentrations of growth factors (platelet-derived (AA, AB, BB), vascular endothelial, insulin-like, and transforming growth factor β) in platelet lysate 1.7-148.7-fold surpassed the corresponding parameters in fetal calf serum. After replacement of fetal calf serum with platelet lysate in the culture medium (0, 25, 50, 75, and 100%), the count of multipotent mesenchymal stromal cells on day 7 (in comparison with day 1) increased by 154.8, 206.6, 228.2, 367.7, and 396.5%, respectively. Thus, platelet lysate can be an adequate non-xenogenic alternative for fetal calf serum. PMID:24319712

  14. Platelets in Inflammation and Atherogenesis

    PubMed Central

    Nording, Henry M.; Seizer, Peter; Langer, Harald F.

    2015-01-01

    Platelets contribute to processes beyond thrombus formation and may play a so far underestimated role as an immune cell in various circumstances. This review outlines immune functions of platelets in host defense, but also how they may contribute to mechanisms of infectious diseases. A particular emphasis is placed on the interaction of platelets with other immune cells. Furthermore, this article outlines the features of atherosclerosis as an inflammatory vascular disease highlighting the role of platelet crosstalk with cellular and soluble factors involved in atheroprogression. Understanding, how platelets influence these processes of vascular remodeling will shed light on their role for tissue homeostasis beyond intravascular thrombosis. Finally, translational implications of platelet-mediated inflammation in atherosclerosis are discussed. PMID:25798138

  15. Exposure of fibrinogen receptors in human platelets by surface proteolysis with elastase.

    PubMed Central

    Kornecki, E; Ehrlich, Y H; De Mars, D D; Lenox, R H

    1986-01-01

    Human platelets that were preincubated with porcine elastase aggregated spontaneously upon the addition of fibrinogen. Maximal aggregation to fibrinogen was observed with platelets pretreated with an elastase concentration of 111 micrograms/ml, and half-maximal aggregation occurred after treatment with 11 micrograms/ml elastase. Binding of radiolabeled fibrinogen to elastase-treated platelets was specific, saturable, and showed a single class of 48,400 +/- 9,697 fibrinogen-binding sites per platelet with a dissociation constant of 6.30 +/- 1.48 X 10(-7) M. ATP, apyrase, and the stimulators of platelet adenylate cyclase forskolin, prostaglandin E1, prostacyclin, and N6, 2'-O-dibutyryl cyclic AMP did not inhibit the fibrinogen-induced aggregation of elastase-treated platelets. EDTA completely blocked the initiation of aggregation and reversed the fibrinogen-induced aggregation of elastase-treated platelets. Monoclonal and polyclonal antibodies directed against glycoproteins (GP) IIb and IIIa completely blocked the fibrinogen-induced aggregation of elastase-treated platelets. Immunoprecipitates with these antibodies obtained from detergent extracts of surface-radiolabeled, intact, and elastase-treated platelets contained the glycoproteins IIb and IIIa. We conclude that surface proteolysis by low concentrations of elastase can expose fibrinogen-binding sites associated with GPIIb and GPIIIa on the platelet surface, resulting in spontaneous aggregation upon the addition of fibrinogen. These findings may be relevant to hemostatic changes observed in patients with increased levels of circulating elastase. Images PMID:3005363

  16. Anomalous columnar order of charged colloidal platelets.

    PubMed

    Morales-Anda, L; Wensink, H H; Galindo, A; Gil-Villegas, A

    2012-01-21

    Monte Carlo computer simulations are carried out for a model system of like-charged colloidal platelets in the isothermal-isobaric ensemble (NpT). The aim is to elucidate the role of electrostatic interactions on the structure of synthetic clay systems at high particle densities. Short-range repulsions between particles are described by a suitable hard-core model representing a discotic particle. This potential is supplemented with an electrostatic potential based on a Yukawa model for the screened Coulombic potential between infinitely thin disklike macro-ions. The particle aspect-ratio and electrostatic parameters were chosen to mimic an aqueous dispersion of thin, like-charged, rigid colloidal platelets at finite salt concentration. An examination of the fluid phase diagram reveals a marked shift in the isotropic-nematic transition compared to the hard cut-sphere reference system. Several statistical functions, such as the pair correlation function for the center-of-mass coordinates and structure factor, are obtained to characterize the structural organization of the platelets phases. At low salinity and high osmotic pressure we observe anomalous hexagonal columnar structures characterized by interpenetrating columns with a typical intercolumnar distance corresponding to about half of that of a regular columnar phase. Increasing the ionic strength leads to the formation of glassy, disordered structures consisting of compact clusters of platelets stacked into finite-sized columns. These so-called "nematic columnar" structures have been recently observed in systems of charge-stabilized gibbsite platelets. Our findings are corroborated by an analysis of the static structure factor from a simple density functional theory. PMID:22280777

  17. Inhibition of Primary ADP-Induced Platelet Aggregation in Normal Subjects after Administration of Nitrofurantoin (Furadantin)

    PubMed Central

    Rossi, Ennio C.; Levin, Nathan W.

    1973-01-01

    The evidence indicating that platelets may play a role in the occurrence of certain thromboembolic phenomena has stimulated a search for inhibitors of platelet function. This report presents data to indicate that nitrofurantoin is a potent inhibitor of primary ADP-induced platelet aggregation. The addition of 10 μM nitrofurantoin to citrated platelet-rich plasma obtained from 12 normal subjects produced a 29±6% (2 SD) inhibition of the velocity of platelet aggregation induced by 2 μM ADP. The inhibitory effect of nitrofurantoin demonstrated competitive kinetics in respect to ADP. The intravenous (180 mg) or oral (200 mg) administration of nitrofurantoin produced a serum nitrofurantoin concentration ranging from 2.7 to 23 μM in 28 normal subjects. Platelet-rich plasma obtained from these subjects demonstrated inhibition of the velocity of ADP-induced platelet aggregation that correlated with the log of the serum nitrofurantoin concentration (P < 0.001). Collagen-induced platelet aggregation was also inhibited in a dose-related manner, and the bleeding time was significantly prolonged in the two subjects with the highest serum nitrofurantoin concentration. These studies indicate that nitrofurantoin in vivo inhibits platelet function to a degree that is proportional to the serum nitrofurantoin concentration. PMID:4729043

  18. 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

  19. Exposure to acrolein by inhalation causes platelet activation

    SciTech Connect

    Sithu, Srinivas D.; Srivastava, Sanjay; Siddiqui, Maqsood A.; Vladykovskaya, Elena; Riggs, Daniel W.; Conklin, Daniel J.; Haberzettl, Petra; O'Toole, Timothy E.; Bhatnagar, Aruni; D'Souza, Stanley E.

    2010-10-15

    Acrolein is a common air pollutant that is present in high concentrations in wood, cotton, and tobacco smoke, automobile exhaust and industrial waste and emissions. Exposure to acrolein containing environmental pollutants such as tobacco smoke and automobile exhaust has been linked to the activation of the coagulation and hemostasis pathways and thereby to the predisposition of thrombotic events in human. To examine the effects of acrolein on platelets, adult male C57Bl/6 mice were subjected acute (5 ppm for 6 h) or sub-chronic (1 ppm, 6 h/day for 4 days) acrolein inhalation exposures. The acute exposure to acrolein did not cause pulmonary inflammation and oxidative stress, dyslipidemia or induce liver damage or muscle injury. Platelet GSH levels in acrolein-exposed mice were comparable to controls, but acrolein-exposure increased the abundance of protein-acrolein adducts in platelets. Platelets isolated from mice, exposed to both acute and sub-chronic acrolein levels, showed increased ADP-induced platelet aggregation. Exposure to acrolein also led to an increase in the indices of platelet activation such as the formation of platelet-leukocyte aggregates in the blood, plasma PF4 levels, and increased platelet-fibrinogen binding. The bleeding time was decreased in acrolein exposed mice. Plasma levels of PF4 were also increased in mice exposed to environmental tobacco smoke. Similar to inhalation exposure, acrolein feeding to mice also increased platelet activation and established a pro-thrombotic state in mice. Together, our data suggest that acrolein is an important contributing factor to the pro-thrombotic risk in human exposure to pollutants such as tobacco smoke or automobile exhaust, or through dietary consumption.

  20. EXPOSURE TO ACROLEIN BY INHALATION CAUSES PLATELET ACTIVATION

    PubMed Central

    Sithu, Srinivas D; Srivastava, Sanjay; Siddiqui, Maqsood A; Vladykovskaya, Elena; Riggs, Daniel W; Conklin, Daniel J; Haberzettl, Petra; O’Toole, Timothy E; Bhatnagar, Aruni; D’Souza, Stanley E

    2010-01-01

    Acrolein is a common air pollutant that is present in high concentrations in wood, cotton, and tobacco smoke, automobile exhaust and industrial waste and emissions. Exposure to acrolein containing environmental pollutants such as tobacco smoke and automobile exhaust has been linked to the activation of the coagulation and hemostasis pathways and thereby to the predisposition of thrombotic events in human. To examine the effects of acrolein on platelets, adult male C57Bl/6 mice were subjected acute (5 ppm for 6 h) or sub-chronic (1 ppm, 6h/day for 4 days) acrolein inhalation exposures. The acute exposure to acrolein did not cause pulmonary inflammation and oxidative stress, dyslipidemia or induce liver damage or muscle injury. Platelet GSH levels in acrolein-exposed mice were comparable to controls, but acrolein-exposure increased the abundance of protein-acrolein adducts in platelets. Platelets isolated from mice, exposed to both acute and sub-chronic acrolein levels, showed increased ADP-induced platelet aggregation. Exposure to acrolein also led to an increase in the indices of platelet activation such as the formation of platelet-leukocyte aggregates in the blood, plasma PF4 levels, and increased platelet-fibrinogen binding. The bleeding time was decreased in acrolein exposed mice. Plasma levels of PF4 were also increased in mice exposed to environmental tobacco smoke. Similar to inhalation exposure, acrolein feeding to mice also increased platelet activation and established a pro-thrombotic state in mice. Together, our data suggest that acrolein is an important contributing factor to the pro-thrombotic risk in human exposure to pollutants such as tobacco smoke or automobile exhaust, or through dietary consumption. PMID:20678513

  1. Immature platelet fraction measured on the Sysmex XN hemocytometer predicts thrombopoietic recovery after autologous stem cell transplantation

    PubMed Central

    van der Linden, Noreen; Klinkenberg, Lieke JJ; Meex, Steven JR; Beckers, Erik AM; de Wit, Norbert CJ; Prinzen, Lenneke

    2014-01-01

    Objectives A period of thrombocytopenia is common after stem cell transplantation (SCT). To prevent serious bleeding complications, prophylactic platelet transfusions are administered. Previous studies have shown that a rise in immature platelets precedes recovery of platelet count. Our aim was to define a cutoff value for immature platelets predicting thrombopoietic recovery within 2 d. Methods Hematological parameters were measured on the Sysmex XN hemocytometer. We calculated reference change values (RCV) for platelets in eight healthy individuals as marker for platelet recovery. To define a cutoff value, we performed ROC analysis using data from 16 autologous SCT patients. Results RCV for platelet concentration was 14.1%. Platelet recovery was observed 13 (median; range 9–31) days after SCT. Increase in immature platelet fraction (IPF) before platelet recovery was seen in all autologous SCT patients. Optimal cutoff IPF was found to be 5.3% for platelet recovery within 2 d (specificity 0.98, sensitivity 0.47, positive predictive value 0.93). Conclusions We identified an optimal cutoff value for IPF 5.3% to predict platelet recovery after autologous SCT within 2 d. Implementing this cutoff value in transfusion strategy may reduce the number of prophylactic platelet transfusions. PMID:24660761

  2. 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.

  3. 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

  4. 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

  5. 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

  6. Subpopulations in purified platelets adhering on glass.

    PubMed

    Donati, Alessia; Gupta, Swati; Reviakine, Ilya

    2016-01-01

    Understanding how platelet activation is regulated is important in the context of cardiovascular disorders and their management with antiplatelet therapy. Recent evidence points to different platelet subpopulations performing different functions. In particular, procoagulant and aggregating subpopulations have been reported in the literature in platelets treated with the GPVI agonists. How the formation of platelet subpopulations upon activation is regulated remains unclear. Here, it is shown that procoagulant and aggregating platelet subpopulations arise spontaneously upon adhesion of purified platelets on clean glass surfaces. Calcium ionophore treatment of the adhering platelets resulted in one platelet population expressing both the procoagulant and the adherent population markers phosphatidylserine and the activated form of GPIIb/IIIa, while all of the platelets expressed CD62P independently of the ionophore treatment. Therefore, all platelets have the capacity to express all three activation markers. It is concluded that platelet subpopulations observed in various studies reflect the dynamics of the platelet activation process. PMID:27338300

  7. Radioimmunoassay of factor V in human plasma and platelets

    SciTech Connect

    Tracy, P.B.; Eide, L.L.; Bowie, E.J.W.; Mann, K.G.

    1982-07-01

    Homogeneous, single-chain human factor V was used to develop a double antibody competition radioimmunoassay to measure factor V concentrations in plasma and platelets. Standard curves were constructed that allow for the detection of as little as 20 ng factor V/ml of plasma. Normal factor V concentrations range from 4 to 14 ..mu..g/ml of plasma with an average value of 7.0 +/- 2.0 ..mu..g/ml (n = 64). No correlation was observed between antigen levels and age or sex. The radioimmunoassay data are consistent with factor V clotting assays, providing freshly drawn plasma is used in the bioassay. Radioimmunoassay of washed platelets indicate that 0.63-1.93 ..mu..g of factor V is present per 2.5 X 10/sup 8/ platelets (6412-14128 molecules of factor V per platelet). When normalized to individual hematocrits and platelet count, the data indicated that platelets contribute approximately 18%-25% of the factor V found in whole blood. In addition, two individuals with functionally deficient factor V were examined and found to be deficient in both antigen and activity.

  8. Exosomes: novel effectors of human platelet lysate activity.

    PubMed

    Torreggiani, E; Perut, F; Roncuzzi, L; Zini, N; Baglìo, S R; Baldini, N

    2014-01-01

    Despite the popularity of platelet-rich plasma (PRP) and platelet lysate (PL) in orthopaedic practice, the mechanism of action and the effectiveness of these therapeutic tools are still controversial. So far, the activity of PRP and PL has been associated with different growth factors (GF) released during platelet degranulation. This study, for the first time, identifies exosomes, nanosized vesicles released in the extracellular compartment by a number of elements, including platelets, as one of the effectors of PL activity. Exosomes were isolated from human PL by differential ultracentrifugation, and analysed by electron microscopy and Western blotting. Bone marrow stromal cells (MSC) treated with three different exosome concentrations (0.6 μg, 5 μg and 50 μg) showed a significant, dose-dependent increase in cell proliferation and migration compared to the control. In addition, osteogenic differentiation assays demonstrated that exosome concentration differently affected the ability of MSC to deposit mineralised matrix. Finally, the analysis of exosome protein content revealed a higher amount of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF-BB) and transforming growth factor beta 1 (TGF-β1) as compared to PL. In regards to RNA content, an enrichment of small RNAs in exosomes as compared to donor platelets has been found. These results suggest that exosomes consistently contribute to PL activity and could represent an advantageous nanodelivery system for cell-free regeneration therapies. PMID:25241964

  9. SDF-1α is a novel autocrine activator of platelets operating through its receptor CXCR4.

    PubMed

    Walsh, Tony G; Harper, Matthew T; Poole, Alastair W

    2015-01-01

    Platelets store and secrete the chemokine stromal cell-derived factor (SDF)-1α upon platelet activation, but the ability of platelet-derived SDF-1α to signal in an autocrine/paracrine manner mediating functional platelet responses relevant to thrombosis and haemostasis is unknown. We sought to explore the role of platelet-derived SDF-1α and its receptors, CXCR4 and CXCR7 in facilitating platelet activation and determine the mechanism facilitating SDF-1α-mediated regulation of platelet function. Using human washed platelets, CXCR4 inhibition, but not CXCR7 blockade significantly abrogated collagen-mediated platelet aggregation, dense granule secretion and thromboxane (Tx) A2 production. Time-dependent release of SDF-1α from collagen-activated platelets supports a functional role for SDF-1α in this regard. Using an in vitro whole blood perfusion assay, collagen-induced thrombus formation was substantially reduced with CXCR4 inhibition. In washed platelets, recombinant SDF-1α in the range of 20-100 ng/mL(-1) could significantly enhance platelet aggregation responses to a threshold concentration of collagen. These enhancements were completely dependent on CXCR4, but not CXCR7, which triggered TxA2 production and dense granule secretion. Rises in cAMP were significantly blunted by SDF-1α, which could also enhance collagen-mediated Ca2+ mobilisation, both of which were mediated by CXCR4. This potentiating effect of SDF-1α primarily required TxA2 signalling acting upstream of dense granule secretion, whereas blockade of ADP signalling could only partially attenuate SDF-1α-induced platelet activation. Therefore, this study supports a potentially novel autocrine/paracrine role for platelet-derived SDF-1α during thrombosis and haemostasis, through a predominantly TxA2-dependent and ADP-independent pathway. PMID:25283599

  10. Inhibition of platelet aggregation and reduced formation of thromboxane and lipoxygenase products in platelets by oil of cloves.

    PubMed

    Srivastava, K C; Justesen, U

    1987-09-01

    Oil of cloves (OC) was found to be a potent inhibitor of platelet aggregation induced by arachidonic acid (AA), collagen and epinephrine; in this respect it was most effective against AA-induced aggregation. Inhibition of aggregation by OC seems to be mediated through a reduced formation of thromboxane as indicated by the following experimental evidence. (i) OC inhibited TxB2 formation in intact as well as lysed platelet preparations from added arachidonate, and (ii) it inhibited the formation of TxB2 from AA-labelled platelets after activation with Ca2+-ionophore A23187. The formation of lipoxygenase derived products was dependent on the concentration of OC used; at its lower concentration their amounts increased but this was found to be reversed at higher concentrations. At all concentrations thromboxane was decreased with a concomitant increase in unused AA. PMID:3118394

  11. [STRUCTURAL CHARACTERIZATION OF PLATELETS AND PLATELET-DERIVED MICROVESICLES].

    PubMed

    Ponomareva, A A; Nevzorova, T A; Mordakhanova, E R; Andrianova, I A; Litvinov, R I

    2016-01-01

    Platelets are the anucleated blood cells, wich together with the fibrin stop bleeding (hemostasis). Cellular microvesicles are membrane-surrounded microparticles released into extracellular space upon activation and/or apoptosis of various cells. Platelet-derived macrovesicles from the major population of circulating blood microparticles that play an important role in hemostasis and thrombosis. Despite numerous studies on the pathophysiology of platelet-derived macrovesicles, mechanisms of their formation and structural details remain poorly understood. Here we investigated the ultrastructure of parental platelets and platelet-derived microvesicles formed in vitro by quiescent cells as well as by cells stimulated with one of the following activators: arachidonic acid, ADP, thrombin, calcium ionophore A23187. Using transmission electron microscopy of human platelets and isolated microvesicles, we analyzed the intracellular origin, steps of formation, structural diversity, and size distributions of the subcellular particles. We have revealed that thrombin, unlike other stimuli, not only induced vesiculation of the plasma membrane but also caused break-up of the cells followed by formation of microparticles that are comparable with microvesicles by size. A fraction of these microparticles contained cellular organelles surrounded by a thin membrane. The size of platelet-derived macrovesicles varied from 30 nm to 500 nm, however, the size distributions depended on the nature of a cell-activating stimulus. The results obtained provide new information about the formation of platelet-derived macrovesicles and their structural diversity, wich is important to understand their multiple functions in normal and disease states. PMID:27228656

  12. Phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) by the anti-platelet drug, cilostazol, in platelets.

    PubMed

    Sudo, Toshiki; Ito, Hideki; Kimura, Yukio

    2003-09-01

    Vasodilator-stimulated phosphoprotein (VASP) is a regulator of actin dynamics in platelets and a common substrate of both cAMP- and cGMP-dependent protein kinases (PKA and PKG). Elevations of the cAMP and cGMP concentration have been shown to inhibit platelet aggregation. Intracellular levels of cAMP and cGMP are regulated by the synthesizing system of adenylate cyclases, and hydrolysis by cyclic nucleotide phosphodiesterases (PDEs). The present study examined the effect of the anti-platelet drug, cilostazol, which inhibits PDE3 activity, on VASP phosphorylation in platelets. VASP phosphorylation was examined by immunoblotting with an anti-VASP antibody, M4, and an anti-phospho-VASP antibody, 16C2. Cilostazol phosphorylated VASP at both Ser157 and Ser239 in a concentration-dependent manner, but EHNA (PDE2 inhibitor), dipyridamole and zaprinast (PDE5 inhibitors) did not. Forskolin (adenylate cyclase activator) and sodium nitroprusside (SNP, NO donor) resulted in the VASP phosphorylation, with increase in the cAMP and cGMP level, respectively. Cilostazol increased cAMP, but not cGMP levels, in platelets. EHNA, zaprinast and dipyridamole, had no effect on cAMP and cGMP levels. The PKA/PKG inhibitor, H-89, inhibited VASP phosphorylation by cilostazol. These results demonstrated that cilostazol phosphorylates VASP through the PDE3 inhibition, increase of cAMP level, and PKA activation in platelets. PMID:14602552

  13. The interaction of sodium nitroprusside with human endothelial cells and platelets: nitroprusside and prostacyclin synergistically inhibit platelet function

    SciTech Connect

    Levin, R.I.; Weksler, B.B.; Jaffe, E.A.

    1982-12-01

    Sodium nitroprusside (NP) is a potent vasodilator that also inhibits platelet aggregation. To test the hypothesis that NP causes both of these effects by altering the balance between prostacyclin (PGI2) produced by endothelial cells and thromboxane A2 (TXA2) produced by platelets, we incubated each of these cell types with NP for 5 minutes and assayed the PGI2 and TXA2 produced. NP at pharmacologically achieved doses (0.01--30 micrograms/ml) inhibited platelet aggregation and resultant TXA2 synthesis in a dose- and time-dependent manner (p less than 0.001). The inhibition was not dependent on cAMP production, external calcium concentration, or suppression of TXA2 synthesis. NP did not alter the production of PGI2 by cultured human endothelial cells as measured by radioimmunoassay for 6-Keto-PGF1 alpha, the stable hydrolysis product of PGI2. However, supernates of NP-treated endothelial cells containing low, noninhibitory concentrations of NP unexpectedly inhibited platelet aggregation. This inhibition of platelet aggregation was due to synergy between PGI2 (0.1--3 nM) and NP (p interaction less than 0.03). The synergistic inhibition by NP and PGI2 of platelet aggregation and TXA2 synthesis in vivo may explain some of the beneficial actions of NP in the treatment of hypertension and congestive heart failure.

  14. Platelet Rich Fibrin in Periodontal Regeneration

    PubMed Central

    Arunachalam, Muthukumaraswamy; Pulikkotil, Shaju J.; Sonia, Nath

    2016-01-01

    Periodontitis is a chronic bacterial infection resulting in destruction of the supporting structures of the teeth. Regeneration of the lost tissues has faced difficulties primarily due to the lack of support during the intricate healing processes. A surgical additive which can ‘jump start’ the healing process to a more predictable regenerative process is always on the wish list of any periodontist. Platelet-rich fibrin (PRF) is a second generation platelet concentrate that has been considered to be an important, easy to obtain, predictable surgical additive for periodontal regeneration. This autologous scaffold provides the much needed bio-chemical mediators which has the potential for enhancing reconstruction of the periodontium. This review article tries to understand as to why PRF would be an important link to reach predictable periodontal regeneration. PMID:27386002

  15. Effects of Platelet-Poor Plasma, Platelet-Rich Plasma, and Platelet-Rich Fibrin on Healing of Extraction Sockets with Buccal Dehiscence in Dogs

    PubMed Central

    Hatakeyama, Ichiro; Takahashi, Yukinobu; Omura, Ken

    2014-01-01

    Alveolar bone resorption generally occurs during healing after tooth extraction. This study aimed to evaluate the effects of platelet-poor plasma (PPP), platelet-rich plasma (PRP), and platelet-rich fibrin (PRF) on healing in a ridge-augmentation model of the canine socket with dehiscence of the buccal wall. The third mandibular premolars of 12 beagle dogs were extracted and a 3 mm buccal dehiscence from the alveolar crest to the buccal wall of the extraction socket was created. These sockets were then divided into four groups on the basis of the material used to fill the sockets: PPP, PRP, PRF, and control (no graft material) groups. Results were evaluated at 4 and 8 weeks after surgery. The ultrastructural morphology and constructs of each blood product were studied by a scanning electron microscope (SEM) or calculating concentrations of platelets, fibrinogen, platelet-derived growth factor, and transforming growth factor-β. A total of five microcomputed tomography images of specimens were selected for measurement, and the area occupied by the newly formed bone as well as the horizontal bone width were measured. Moreover, decalcified tissue specimens from each defect were analyzed histologically. The median area of new bone at 4 and 8 weeks and median horizontal bone width at 8 weeks were the highest in the PPP group. However, bone maturation in the PRF and the PRP groups was more progressed than that in the PPP and control groups. By SEM findings, the PRF group showed a more highly condensed fibrin fiber network that was regularly arranged when compared with the PPP and PRP groups. The growth factors released from platelets in PRP indicated higher concentrations than that in PRF. Under more severe conditions for bone formation, as in this experiment, the growth factors released from platelets had a negative effect on bone formation. This study showed that PPP is an effective material for the preservation of sockets with buccal dehiscence. PMID:24098948

  16. Effect of taurine on platelets and the plasma coagulation system.

    PubMed

    Miglis, Mitchell; Wilder, Donna; Reid, Thomas; Bakaltcheva, Irina

    2002-02-01

    It is not yet clear what exact mechanisms are at work in hibernating animals that prevent clot formation and maintain tissue perfusion under conditions of very slow blood flow and increased blood viscosity brought about by the low temperatures. It has been shown that the total amino acid pool increases more then two fold in hibernating animals with taurine accounting for about 50% of this increase [Storey et al., Proc Natl Acad Sci USA 1988; 85(21): 8350-4]. This work investigates the effect of taurine on platelets and the plasma coagulation system. Taurine was added at different concentrations in the range between 5 and 25 mM to donor plasma. Using STA/STA Compact coagulation analyzer the following tests were performed: prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT). At the highest concentration tested (25 mM) taurine prolonged TT by 9%. The prolongation was statistically significant but not clinically significant retaining TT within normal limits (16.7-20.7 s). PT and APTT remained unchanged by taurine. The effect of taurine on platelets was assessed by platelet aggregation by thrombin, extent of platelet shape change (ESC) induced by ADP, and thrombelastography. Taurine at 5 mM final concentration inhibited platelet aggregation by 10%. Increasing taurine concentration to 25 mM did not result in a further augmentation of the inhibitory effect. ESC was unaffected by taurine. Clot strength determined by thrombelastography also remained unchanged by taurine. PMID:11918831

  17. Genomics of platelet disorders.

    PubMed

    Westbury, S K; Mumford, A D

    2016-07-01

    Genetic diagnosis in families with inherited platelet disorders (IPD) is not performed widely because of the genetic heterogeneity of this group of disorders and because in most cases, it is not possible to select single candidate genes for analysis using clinical and laboratory phenotypes. Next-generation sequencing (NGS) technology has revolutionized the scale and cost-effectiveness of genetic testing, and has emerged as a valuable tool for IPD. This review examines the potential utility of NGS as a diagnostic tool to streamline detection of causal variants in known IPD genes and as a vehicle for new gene discovery. PMID:27405671

  18. 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

  19. Platelet abnormalities in nephrotic syndrome.

    PubMed

    Eneman, Benedicte; Levtchenko, Elena; van den Heuvel, Bert; Van Geet, Chris; Freson, Kathleen

    2016-08-01

    Nephrotic syndrome (NS) is a common kidney disease associated with a significantly increased risk of thrombotic events. Alterations in plasma levels of pro- and anti-coagulant factors are involved in the pathophysiology of venous thrombosis in NS. However, the fact that the risk of both venous and arterial thrombosis is elevated in NS points to an additional role for blood platelets. Increased platelet counts and platelet hyperactivity have been observed in nephrotic children. Platelet hyperaggregability, increased release of active substances, and elevated surface expression of activation-dependent platelet markers have been documented. The mechanisms underlying those platelet alterations are multifactorial and are probably due to changes in plasma levels of platelet-interfering proteins and lipid changes, as a consequence of nephrosis. The causal relationship between platelet alterations seen in NS and the occurrence of thromboembolic phenomena remains unclear. Moreover, the efficiency of prophylactic treatment using antiplatelet agents for the prevention of thrombotic complications in nephrotic patients is also unknown. Thus, antiplatelet medication is currently not generally recommended for routine prophylactic therapy. PMID:26267676

  20. Platelet adhesiveness in diabetes mellitus

    PubMed Central

    Shaw, S.; Pegrum, G. D.; Wolff, Sylvia; Ashton, W. L.

    1967-01-01

    Platelet adhesiveness has been assessed on whole blood from a series of 34 diabetics and 50 control subjects using adenosine diphosphate (A.D.P.) and by adherence to glass microspherules (ballotini). Using both techniques it was possible to demonstrate a significant increase in platelet adhesiveness in the diabetic patients. PMID:5614070

  1. Platelets: production, morphology and ultrastructure.

    PubMed

    Thon, Jonathan N; Italiano, Joseph E

    2012-01-01

    Platelets are anucleate, discoid cells, roughly 2-3 μm in diameter that function primarily as regulators of hemostasis, but also play secondary roles in angiogensis and innate immunity. Although human adults contain nearly one trillion platelets in circulation that are turned over every 8-10 days, our understanding of the mechanisms involved in platelet production is still incomplete. Platelets stem from large (30-100 μm) nucleated cells called megakaryocytes that reside primarily in the bone marrow. During maturation megakaryocytes extend long proplatelet elongations into sinusoidal blood vessels from which platelets ultimately release. During this process, platelets develop a number of distinguishable structural elements including: a delimited plasma membrane; invaginations of the surface membrane that form the open canalicular system (OCS); a closed-channel network of residual endoplasmic reticulum that form the dense tubular system (DTS); a spectrin-based membrane skeleton; an actin-based cytoskeletal network; a peripheral band of microtubules; and numerous organelles including α-granules, dense-granules, peroxisomes, lysosomes, and mitochondria. Proplatelet elongation and platelet production is an elaborate and complex process that defines the morphology and ultrastructure of circulating platelets, and is critical in understanding their increasingly numerous and varied biological functions. PMID:22918725

  2. In vitro platelet aggregation and oxidative stress caused by amorphous silica nanoparticles

    PubMed Central

    Nemmar, Abderrahim; Yuvaraju, Priya; Beegam, Sumaya; Yasin, Javed; Dhaheri, Rauda Al; Fahim, Mohamed A; Ali, Badreldin H

    2015-01-01

    Amorphous silica nanoparticles (SiNP) are being investigated for their potential use in various industrial and medical fields. Therefore, the assessment of their possible pathophysiological effect on circulating cells such as platelets is essential. We recently showed that intraperitoneal administration of SiNP causes proinflammatory and prothrombotic responses in vivo. However, little is known about the interaction of amorphous SiNP with platelets in vitro. Presently, we investigated the in vitro effects of SiNP (1, 5 and 25 μg/ml) on platelet aggregation, oxidative stress and intracellular calcium in mouse platelets. Incubation of platelets with SiNP caused a significant and dose-dependent platelet aggregation. Similarly, the activity of lactate dehydrogenase (as a marker of cell membrane integrity) was significantly increased by SiNP. Total antioxidant activity and lipid platelets vulnerability to in vitro peroxidation (measured by malondialdehyde production) were significantly increased after SiNP exposure. Additionally, SiNP exposure significantly increased the cytosolic calcium concentration. In conclusion, our in vitro data show that incubation of platelets with SiNP caused platelet aggregation, oxidative stress and increased intracellular calcium. This finding provides evidence on the toxicity of SiNP on platelet physiology. PMID:26069526

  3. Activated platelets rescue apoptotic cells via paracrine activation of EGFR and DNA-dependent protein kinase

    PubMed Central

    Au, A E-L; Sashindranath, M; Borg, R J; Kleifeld, O; Andrews, R K; Gardiner, E E; Medcalf, R L; Samson, A L

    2014-01-01

    Platelet activation is a frontline response to injury, not only essential for clot formation but also important for tissue repair. Indeed, the reparative influence of platelets has long been exploited therapeutically where application of platelet concentrates expedites wound recovery. Despite this, the mechanisms of platelet-triggered cytoprotection are poorly understood. Here, we show that activated platelets accumulate in the brain to exceptionally high levels following injury and release factors that potently protect neurons from apoptosis. Kinomic microarray and subsequent kinase inhibitor studies showed that platelet-based neuroprotection relies upon paracrine activation of the epidermal growth factor receptor (EGFR) and downstream DNA-dependent protein kinase (DNA-PK). This same anti-apoptotic cascade stimulated by activated platelets also provided chemo-resistance to several cancer cell types. Surprisingly, deep proteomic profiling of the platelet releasate failed to identify any known EGFR ligand, indicating that activated platelets release an atypical activator of the EGFR. This study is the first to formally associate platelet activation to EGFR/DNA-PK – an endogenous cytoprotective cascade. PMID:25210793

  4. Platelet-Rich Plasma

    PubMed Central

    Cole, Brian J.; Seroyer, Shane T.; Filardo, Giuseppe; Bajaj, Sarvottam; Fortier, Lisa A.

    2010-01-01

    Context: Platelet-rich plasma (PRP) may affect soft tissue healing via growth factors released after platelet degranulation. Because of this potential benefit, clinicians have begun to inject PRP for the treatment of tendon, ligament, muscle, and cartilage injuries and early osteoarthritis. Evidence Acquisition: A PubMed search was performed for studies relating to PRP, growth factors, and soft tissue injuries from 1990 to 2010. Relevant references from these studies were also retrieved. Results: Soft tissue injury is a major source of disability that may often be complicated by prolonged and incomplete recovery. Numerous growth factors may potentiate the healing and regeneration of tendons and ligaments. The potential benefits of biologically enhanced healing processes have led to a recent interest in the use of PRP in orthopaedic sports medicine. There has been widespread anecdotal use of PRP for muscle strains, tendinopathy, and ligament injuries and as a surgical adjuvant to rotator cuff repair, anterior cruciate ligament reconstruction, and meniscal or labral repairs. Although the fascination with this emerging technology has led to a dramatic increase in its use, scientific data supporting this use are still in their infancy. Conclusions: The literature is replete with studies on the basic science of growth factors and their relation to the maintenance, proliferation, and regeneration of various tissues and tissue-derived cells. Despite the promising results of several animal studies, well-controlled human studies are lacking. PMID:23015939

  5. High efficient configuration design and simulation of platelet heat exchanger in solar thermal thruster

    NASA Astrophysics Data System (ADS)

    Xing, BaoYu; Liu, Kun; Huang, MinChao; Cheng, MouSen

    2014-06-01

    Solar thermal propulsion system includes solar thermal propulsion and nuclear thermal propulsion, and it is a significant issue to improve the heat transfer efficiency of the solar thermal thruster. This paper proposes a platelet configuration to be used in the heat exchanger core, which is the most important component of solar thermal system. The platelet passage can enhance the heat transfer between the propellant and the hot core heated by the concentrated sunlight. Based on fluid-solid coupled heat transfer, the paper utilized the platelet heat transfer characteristic to simulate the heat transfer and flow field of the platelet passage. A coupled system includes the coupled flow and heat transfer between the fluid region and solid region. The simulation result shows that the propellant can be heated to the design temperature of 2300K in platelet passage of the thermal propulsion system, and the fluid-solid coupled method can solve the heat transfer in the platelet structure more precisely.

  6. Crosstalk between platelets and PBMC: New evidence in wound healing.

    PubMed

    Nami, Niccolò; Feci, Luca; Napoliello, Luca; Giordano, Antonio; Lorenzini, Sauro; Galeazzi, Mauro; Rubegni, Pietro; Fimiani, Michele

    2016-01-01

    Platelet-derived products have proven useful in accelerating healing processes and tissue regeneration. However, despite their widespread use in clinical practice, the cellular and molecular mechanisms involved have not yet been completely clarified. Recent studies show that interaction between platelet gel (PG) and peripheral blood mononuclear cells (PBMC) can result in activation of PBMC and production of several cytokines involved in wound healing and tissue repair. The aim of our study was to analyze whether crosstalk between platelets and PBMC can influence wound healing by modulating release of VEGF, bFGF and IL-10 by PBMC. Cultures of PBMC alone and co-cultures with autologous PG of 24 healthy volunteers were incubated under normoxia for 24 h. VEGF, bFGF and IL-10 concentration and expression were then analyzed in supernatants by ELISA and by real-time RT-PCR. We observed a down-regulation of VEGF and bFGF release and an up-regulation of IL-10 release in co-cultures of PBMC and PG. Platelets are not only important in the early stages of the healing process (clot formation, direct release of growth factors), but also can influence the whole process of tissue regeneration by modulating synthesis and release of VEGF, bFGF and IL-10 by PBMC. These effects could give platelets a new key role in the control of healing processes and provide insights into the clinical success of platelet-derived products in many medical fields. PMID:26030799

  7. Enhancement of Platelet Aggregation by Ursolic Acid and Oleanolic Acid

    PubMed Central

    Kim, Mikyung; Han, Chang-ho; Lee, Moo-Yeol

    2014-01-01

    The pentacyclic triterpenoid ursolic acid (UA) and its isomer oleanolic acid (OA) are ubiquitous in food and plant medicine, and thus are easily exposed to the population through natural contact or intentional use. Although they have diverse health benefits, reported cardiovascular protective activity is contentious. In this study, the effect of UA and OA on platelet aggregation was examined on the basis that alteration of platelet activity is a potential process contributing to cardiovascular events. Treatment of UA enhanced platelet aggregation induced by thrombin or ADP, which was concentration-dependent in a range of 5–50 μM. Quite comparable results were obtained with OA, in which OA-treated platelets also exhibited an exaggerated response to either thrombin or ADP. UA treatment potentiated aggregation of whole blood, while OA failed to increase aggregation by thrombin. UA and OA did not affect plasma coagulation assessed by measuring prothrombin time and activated partial thromboplastin time. These results indicate that both UA and OA are capable of making platelets susceptible to aggregatory stimuli, and platelets rather than clotting factors are the primary target of them in proaggregatory activity. These compounds need to be used with caution, especially in the population with a predisposition to cardiovascular events. PMID:25009707

  8. Chlorogenic Acid Inhibits Human Platelet Activation and Thrombus Formation

    PubMed Central

    Fuentes, Eduardo; Caballero, Julio; Alarcón, Marcelo; Rojas, Armando; Palomo, Iván

    2014-01-01

    Background Chlorogenic acid is a potent phenolic antioxidant. However, its effect on platelet aggregation, a critical factor in arterial thrombosis, remains unclear. Consequently, chlorogenic acid-action mechanisms in preventing platelet activation and thrombus formation were examined. Methods and Results Chlorogenic acid in a dose-dependent manner (0.1 to 1 mmol/L) inhibited platelet secretion and aggregation induced by ADP, collagen, arachidonic acid and TRAP-6, and diminished platelet firm adhesion/aggregation and platelet-leukocyte interactions under flow conditions. At these concentrations chlorogenic acid significantly decreased platelet inflammatory mediators (sP-selectin, sCD40L, CCL5 and IL-1β) and increased intraplatelet cAMP levels/PKA activation. Interestingly, SQ22536 (an adenylate cyclase inhibitor) and ZM241385 (a potent A2A receptor antagonist) attenuated the antiplatelet effect of chlorogenic acid. Chlorogenic acid is compatible to the active site of the adenosine A2A receptor as revealed through molecular modeling. In addition, chlorogenic acid had a significantly lower effect on mouse bleeding time when compared to the same dose of aspirin. Conclusions Antiplatelet and antithrombotic effects of chlorogenic acid are associated with the A2A receptor/adenylate cyclase/cAMP/PKA signaling pathway. PMID:24598787

  9. 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.

  10. Platelet-Rich Plasma and Platelet Gel: A Review

    PubMed Central

    Everts, Peter A.M.; Knape, Johannes T.A.; Weibrich, Gernot; Schönberger, Jacques P.A.M.; Hoffmann, Johannes; Overdevest, Eddy P.; Box, Henk A.M.; van Zundert, André

    2006-01-01

    Abstract: Strategies to reduce blood loss and transfusion of allogeneic blood products during surgical procedures are important in modern times. The most important and well-known autologous techniques are preoperative autologous predonation, hemodilution, perioperative red cell salvage, postoperative wound blood autotransfusion, and pharmacologic modulation of the hemostatic process. At present, new developments in the preparation of preoperative autologous blood component therapy by whole blood platelet-rich plasma (PRP) and platelet-poor plasma (PPP) sequestration have evolved. This technique has been proven to reduce the number of allogeneic blood transfusions during open heart surgery and orthopedic operations. Moreover, platelet gel and fibrin sealant derived from PRP and PPP mixed with thrombin, respectively, can be exogenously applied to tissues to promote wound healing, bone growth, and tissue sealing. However, to our disappointment, not many well-designed scientific studies are available, and many anecdotic stories exist, whereas questions remain to be answered. We therefore decided to study perioperative blood management in more detail with emphasis on the application and production of autologous platelet gel and the use of fibrin sealant. This review addresses a large variety of aspects relevant to platelets, platelet-rich plasma, and the application of platelet gel. In addition, an overview of recent animal and human studies is presented. PMID:16921694

  11. 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.

  12. Wdr1-Dependent Actin Reorganization in Platelet Activation.

    PubMed

    Dasgupta, Swapan K; Le, Anhquyen; Da, Qi; Cruz, Miguel; Rumbaut, Rolando E; Thiagarajan, Perumal

    2016-01-01

    In resting platelets, the integrin αIIbβ3 is present in a low-affinity "bent" state. During platelet aggregation, intracytoplasmic signals induce conformational changes (inside-out signaling) that result in a "swung-out" conformation competent to bind ligands such as fibrinogen. The cytoskeleton plays an essential role in αIIbβ3 activation. We investigated the role of the actin interacting protein Wdr1 in αIIbβ3 activation. Wdr1-hypomorphic mice had a prolonged bleeding time (> 10 minutes) compared to that of wild-type mice (2.1 ± 0.7 minutes). Their platelets had impaired aggregation to collagen and thrombin. In a FeCl3 induced carotid artery thrombosis model, vessel occlusion in Wdr1-hypomorphic mice was prolonged significantly compared to wild-type mice (9.0 ± 10.5 minutes versus 5.8 ± 12.6 minutes (p = 0.041). Activation-induced binding of JON/A (a conformation-specific antibody to activated αIIbβ3) was significantly less in Wdr1-hypomorphic platelets at various concentrations of collagen, indicating impaired inside-out activation of αIIbβ3, despite a normal calcium response. Actin turnover, assessed by measuring F-actin and G-actin ratios during collagen- and thrombin-induced platelet aggregation, was highly impaired in Wdr1-hypomorphic platelets. Furthermore, talin failed to redistribute and translocate to the cytoskeleton following activation in Wdr1-hypomorphic platelets. These studies show that Wdr1 is essential for talin-induced activation of αIIbβ3 during platelet activation. PMID:27627652

  13. Relevant Aspects of Centrifugation Step in the Preparation of Platelet-Rich Plasma

    PubMed Central

    Perez, Amanda G. M.; Lana, José Fábio S. D.; Rodrigues, Ana Amélia; Luzo, Angela Cristina M.; Belangero, William D.; Santana, Maria Helena A.

    2014-01-01

    Introduction. Platelet-Rich Plasma (PRP) is rich in growth factors, playing important role in tissue healing. The wide variation of reported protocols for preparation of PRP leads to variable compositions, which induce different biological responses and prevent results comparison. This study aims to highlight relevant aspects of the centrifugation step to obtain reproducible results and overall quality. Material and Methods. Samples of blood were collected from 20 healthy donors that have signed free informed consent. Two centrifugation steps (spins) were analyzed for the influence of centrifugal acceleration, time, processed volume, and platelet gradient. The Pure Platelet-Rich Plasma (P-PRP) was characterized as platelet concentration, integrity, and viability (sP-selectin measurement). Results. Lower centrifugal accelerations favour platelet separation. The processing of 3.5 mL of blood at 100 ×g for 10 min (1st spin), 400 ×g for 10 min (2nd spin), withdrawing 2/3 of remnant plasma, promoted high platelet recovery (70–80%) and concentration (5x) maintaining platelet integrity and viability. The recovery of platelets was reduced for a larger WB volume (8.5 mL) processed. Conclusion. Centrifugal acceleration, time, WB processed volume, and minimization of the platelet gradient before sampling are relevant aspects to ensure reproducible compositions within the autologous nature of PRP. PMID:25006472

  14. Degranulation of rabbit platelets with PAF-acether: a new procedure for unravelling the mode of action of platelet-activating substances.

    PubMed

    Vargaftig, B B; Joseph, D; Marlas, G; Chevance, L G

    1982-08-24

    Aggregation and secretion of ATP induced by thrombin, collagen, the snake venom component convulxin and platelet-activating factor (PAF-acether) were studied after the exposure of rabbit platelets to 1 microM of PAF-acether. This concentration, which is around 6 orders of magnitude above the concentration needed to induce full aggregation, was required to remove most of the releasable ATP from the platelets. The depleted platelets aggregated to PAF-acether, to thrombin and to convulxin under conditions where only very low amounts of ATP were secreted, confirming that these agents do not require the release of dense body components to trigger aggregation. Furthermore, when exposure to PAF-acether was associated to inactivation of platelet cyclooxygenase with aspirin, aggregation to thrombin persisted, validating the claim that thrombin induces aggregation by a third pathway unrelated to ADP and to thromboxane A2. Aggregation by collagen was markedly reduced by exposure of the platelets to PAF-acether or to aspirin; when both procedures were associated, aggregation was suppressed. Failure to desensitize the rabbit platelets to PAF-acether upon exposure to high amounts of it indicates the absence of irreversible membrane changes due to PAF-acether, and allows its use as a depleting procedure for the dense body materials, which does not affect platelet membrane components as is the case for thrombin. PMID:7135345

  15. Human group II 14 kDa phospholipase A2 activates human platelets.

    PubMed Central

    Polgár, J; Kramer, R M; Um, S L; Jakubowski, J A; Clemetson, K J

    1997-01-01

    Recombinant human group II phospholipase A2 (sPLA2) added to human platelets in the low microg/ml range induced platelet activation, as demonstrated by measurement of platelet aggregation, thromboxane A2 generation and influx of intracellular free Ca2+ concentration and by detection of time-dependent tyrosine phosphorylation of platelet proteins. The presence of Ca2+ at low millimolar concentrations is a prerequisite for the activation of platelets by sPLA2. Mg2+ cannot replace Ca2+. Mg2+, given in addition to the necessary Ca2+, inhibits sPLA2-induced platelet activation. Pre-exposure to sPLA2 completely blocked the aggregating effect of a second dose of sPLA2. Albumin or indomethacin inhibited sPLA2-induced aggregation, similarly to the inhibition of arachidonic acid-induced aggregation. Platelets pre-treated with heparitinase or phosphatidylinositol-specific phospholipase C lost their ability to aggregate in response to sPLA2, although they still responded to other agonists. This suggests that a glycophosphatidylinositol-anchored platelet-membrane heparan sulphate proteoglycan is the binding site for sPLA2 on platelets. Previous reports have stated that sPLA2 is unable to activate platelets. The inhibitory effect of albumin and Mg2+, frequently used in aggregation studies, and the fact that isolated platelets lose their responsiveness to sPLA2 relatively quickly, may explain why the platelet-activating effects of sPLA2 have not been reported earlier. PMID:9355761

  16. Shiga toxin binds to activated platelets.

    PubMed

    Ghosh, S A; Polanowska-Grabowska, R K; Fujii, J; Obrig, T; Gear, A R L

    2004-03-01

    Hemolytic uremic syndrome (HUS) is associated with acute renal failure in children and can be caused by Shiga toxin (Stx)-producing Escherichia coli. Thrombocytopenia and formation of renal thrombi are characteristic of HUS, suggesting that platelet activation is involved in its pathogenesis. However, whether Shiga toxin directly activates platelets is controversial. The present study evaluates if potential platelet sensitization during isolation by different procedures influences platelet interaction with Shiga toxin. Platelets isolated from sodium citrate anticoagulated blood were exposed during washing to EDTA and higher g forces than platelets prepared from acid-citrate-dextrose (ACD) plasma. Platelet binding of Stx was significantly higher in EDTA-washed preparations relative to ACD-derived platelets. Binding of Stx was also increased with ACD-derived platelets when activated with thrombin (1 U mL-1) and exposure of the Gb3 Stx receptor was detected only on platelets subjected to EDTA, higher g forces or thrombin. EDTA-exposed platelets lost their normal discoid shape and were larger. P-selectin (CD62P) exposure was significantly increased in EDTA-washed preparations relative to ACD-derived platelets, suggesting platelet activation. Taken together, these results suggest that direct binding of Stx occurs only on 'activated' platelets rather than on resting platelets. The ability of Stx to interact with previously activated platelets may be an important element in understanding the pathogenesis of HUS. PMID:15009469

  17. Platelet Interaction with Innate Immune Cells

    PubMed Central

    Kral, Julia Barbara; Schrottmaier, Waltraud Cornelia; Salzmann, Manuel; Assinger, Alice

    2016-01-01

    Summary Beyond their traditional role in haemostasis and thrombosis, platelets are increasingly recognised as immune modulatory cells. Activated platelets and platelet-derived microparticles can bind to leukocytes, which stimulates mutual activation and results in rapid, local release of platelet-derived cytokines. Thereby platelets modulate leukocyte effector functions and contribute to inflammatory and immune responses to injury or infection. Platelets enhance leukocyte extravasation, differentiation and cytokine release. Platelet-neutrophil interactions boost oxidative burst, neutrophil extracellular trap formation and phagocytosis and play an important role in host defence. Platelet interactions with monocytes propagate their differentiation into macrophages, modulate cytokine release and attenuate macrophage functions. Depending on the underlying pathology, platelets can enhance or diminish leukocyte cytokine production, indicating that platelet-leukocyte interactions represent a fine balanced system to restrict excessive inflammation during infection. In atherosclerosis, platelet interaction with neutrophils, monocytes and dendritic cells accelerates key steps of atherogenesis by promoting leukocyte extravasation and foam cell formation. Platelet-leukocyte interactions at sites of atherosclerotic lesions destabilise atherosclerotic plaques and promote plaque rupture. Leukocytes in turn also modulate platelet function and production, which either results in enhanced platelet destruction or increased platelet production. This review aims to summarise the key effects of platelet-leukocyte interactions in inflammation, infection and atherosclerosis. PMID:27226790

  18. Radioimmune assay of human platelet prostaglandin synthetase

    SciTech Connect

    Roth, G.J.; Machuga, E.T.

    1982-02-01

    Normal platelet function depends, in part, on platelet PG synthesis. PG synthetase (cyclo-oxygenase) catalyzes the first step in PG synthesis, the formation of PGH/sub 2/ from arachidonic acid. Inhibition of the enzyme by ASA results in an abnormality in the platelet release reaction. Patients with pparent congenital abnormalities in the enzyme have been described, and the effects have been referred to as ''aspirin-like'' defects of the platelet function. These patients lack platelet PG synthetase activity, but the actual content of PG synthetase protein in these individuals' platelets is unknown. Therefore an RIA for human platelet PG synthetase would provide new information, useful in assessing the aspirin-like defects of platelet function. An RIA for human platelet PG synthetase is described. The assay utilizes a rabbit antibody directed against the enzyme and (/sup 125/I)-labelled sheep PG synthetase as antigen. The human platelet enzyme is assayed by its ability to inhibit precipitation of the (/sup 125/I)antigen. The assay is sensitive to 1 ng of enzyme. By the immune assay, human platelets contain approximately 1200 ng of PG synethetase protein per 1.5 mg of platelet protein (approximately 10/sup 9/ platelets). This content corresponds to 10,000 enzyme molecules per platelet. The assay provides a rapid and convenient assay for the human platelet enzyme, and it can be applied to the assessment of patients with apparent platelet PG synthetase (cyclo-oxygenase) deficiency.

  19. Platelet Interaction with Innate Immune Cells.

    PubMed

    Kral, Julia Barbara; Schrottmaier, Waltraud Cornelia; Salzmann, Manuel; Assinger, Alice

    2016-03-01

    Beyond their traditional role in haemostasis and thrombosis, platelets are increasingly recognised as immune modulatory cells. Activated platelets and platelet-derived microparticles can bind to leukocytes, which stimulates mutual activation and results in rapid, local release of platelet-derived cytokines. Thereby platelets modulate leukocyte effector functions and contribute to inflammatory and immune responses to injury or infection. Platelets enhance leukocyte extravasation, differentiation and cytokine release. Platelet-neutrophil interactions boost oxidative burst, neutrophil extracellular trap formation and phagocytosis and play an important role in host defence. Platelet interactions with monocytes propagate their differentiation into macrophages, modulate cytokine release and attenuate macrophage functions. Depending on the underlying pathology, platelets can enhance or diminish leukocyte cytokine production, indicating that platelet-leukocyte interactions represent a fine balanced system to restrict excessive inflammation during infection. In atherosclerosis, platelet interaction with neutrophils, monocytes and dendritic cells accelerates key steps of atherogenesis by promoting leukocyte extravasation and foam cell formation. Platelet-leukocyte interactions at sites of atherosclerotic lesions destabilise atherosclerotic plaques and promote plaque rupture. Leukocytes in turn also modulate platelet function and production, which either results in enhanced platelet destruction or increased platelet production. This review aims to summarise the key effects of platelet-leukocyte interactions in inflammation, infection and atherosclerosis. PMID:27226790

  20. Culture of human cell lines by a pathogen-inactivated human platelet lysate.

    PubMed

    Fazzina, R; Iudicone, P; Mariotti, A; Fioravanti, D; Procoli, A; Cicchetti, E; Scambia, G; Bonanno, G; Pierelli, L

    2016-08-01

    Alternatives to the use of fetal bovine serum (FBS) have been investigated to ensure xeno-free growth condition. In this study we evaluated the efficacy of human platelet lysate (PL) as a substitute of FBS for the in vitro culture of some human cell lines. PL was obtained by pools of pathogen inactivated human donor platelet (PLT) concentrates. Human leukemia cell lines (KG-1, K562, JURKAT, HL-60) and epithelial tumor cell lines (HeLa and MCF-7) were cultured with either FBS or PL. Changes in cell proliferation, viability, morphology, surface markers and cell cycle were evaluated for each cell line. Functional characteristics were analysed by drug sensitivity test and cytotoxicity assay. Our results demonstrated that PL can support growth and expansion of all cell lines, although the cells cultured in presence of PL experienced a less massive proliferation compared to those grown with FBS. We found a comparable percentage of viable specific marker-expressing cells in both conditions, confirming lineage fidelity in all cultures. Functionality assays showed that cells in both FBS- and PL-supported cultures maintained their normal responsiveness to adriamycin and NK cell-mediated lysis. Our findings indicate that PL is a feasible serum substitute for supporting growth and propagation of haematopoietic and epithelial cell lines with many advantages from a perspective of process standardization, ethicality and product safety. PMID:25944665

  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. 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

  3. Glycans and the platelet life cycle.

    PubMed

    Li, Renhao; Hoffmeister, Karin M; Falet, Hervé

    2016-09-01

    Platelet numbers are intricately regulated to avoid spontaneous bleeding or arterial occlusion and organ damage. The growth factor thrombopoietin (TPO) drives platelet biogenesis by inducing megakaryocyte production. A recent study in mice identified a feedback mechanism by which clearance of aged, desialylated platelets stimulates TPO synthesis by hepatocytes. This new finding generated renewed interest in platelet clearance mechanisms. Here, different established and emerging mechanisms of platelet senescence and clearance will be reviewed with specific emphasis on the role of posttranslational modifications. PMID:27135356

  4. Platelet factor XIIIa release during platelet aggregation and plasma clot strength measured by thrombelastography in patients with coronary artery disease treated with clopidogrel.

    PubMed

    Kreutz, Rolf P; Owens, Janelle; Lu, Deshun; Nystrom, Perry; Jin, Yan; Kreutz, Yvonne; Desta, Zeruesenay; Flockhart, David A

    2015-01-01

    It has been estimated that up to half of circulating factor XIIIa (FXIIIa) is stored in platelets. The release of FXIIIa from platelets upon stimulation with adenosine diphosphate (ADP) in patients with coronary artery disease treated with dual antiplatelet therapy has not been previously examined. Samples from 96 patients with established coronary artery disease treated with aspirin and clopidogrel were examined. Platelet aggregation was performed by light transmittance aggregometry in platelet-rich plasma (PRP), with platelet-poor plasma (PPP) as reference, and ADP 5 µM as agonist. Kaolin-activated thrombelastography (TEG) was performed in citrate PPP. PRP after aggregation was centrifuged and plasma supernatant (PSN) collected. FXIIIa was measured in PPP and PSN. Platelet aggregation after stimulation with ADP 5 µM resulted in 24% additional FXIIIa release in PSN as compared to PPP (99.3 ± 27 vs. 80.3 ± 24%, p < 0.0001). FXIIIa concentration in PSN correlated with maximal plasma clot strength (TEG-G) (r = 0.48, p < 0.0001), but not in PPP (r = 0.15, p = 0.14). Increasing quartiles of platelet-derived FXIIIa were associated with incrementally higher TEG-G (p = 0.012). FXIIIa release was similar between clopidogrel responders and non-responders (p = 0.18). In summary, platelets treated with aspirin and clopidogrel release a significant amount of FXIIIa upon aggregation by ADP. Platelet-derived FXIIIa may contribute to differences in plasma TEG-G, and thus, in part, provide a mechanistic explanation for high clot strength observed as a consequence of platelet activation. Variability in clopidogrel response does not significantly influence FXIIIa release from platelets. PMID:24833046

  5. Platelet Factor XIIIa Release During Platelet Aggregation and Plasma Clot Strength Measured by Thrombelastography in Patients with Coronary Artery Disease Treated with Clopidogrel

    PubMed Central

    Kreutz, Rolf P.; Owens, Janelle; Lu, Deshun; Nystrom, Perry; Jin, Yan; Kreutz, Yvonne; Desta, Zeruesenay; Flockhart, David A.

    2016-01-01

    It has been estimated that up to half of circulating Factor XIIIa (FXIIIa) is stored in platelets. The release of FXIIIa from platelets upon stimulation with ADP in patients with coronary artery disease treated with dual antiplatelet therapy has not been previously examined. Samples from 96 patients with established coronary artery disease treated with aspirin and clopidogrel were examined. Platelet aggregation was performed by light transmittance aggregometry (LTA) in platelet rich plasma (PRP) with platelet poor plasma (PPP) as reference and ADP 5μM as agonist. Kaolin activated TEG was performed in citrate PPP. PRP after aggregation was centrifuged and plasma supernatant (PSN) collected. FXIIIa was measured in PPP and PSN. Platelet aggregation after stimulation with ADP 5μM resulted in 24% additional FXIIIa release in PSN as compared to PPP (99.3 ± 27 vs. 80.3 ± 24 %, p<0.0001). FXIIIa concentration in PSN correlated with maximal plasma clot strength (TEG-G) (r=0.48, p<0.0001), but not in PPP (r=0.15, p=0.14). Increasing quartiles of platelet derived FXIIIa were associated with incrementally higher TEG-G (p=0.012). FXIIIa release was similar between clopidogrel responders and non-responders (p=0.18). In summary, platelets treated with aspirin and clopidogrel release a significant amount of FXIIIa upon aggregation by ADP. Platelet derived FXIIIa may contribute to differences in plasma TEG-G, and thus in part provide a mechanistic explanation for high clot strength observed as a consequence of platelet activation. Variability in clopidogrel response does not significantly influence FXIIIa release from platelets. PMID:24833046

  6. Physiopathology of blood platelets: a model system for studies of cell-to-cell interaction. Progress report, November 1, 1979-October 31, 1980

    SciTech Connect

    1980-01-01

    This report covers the studies on basic mechanisms of cellular interactions, utilizing platelets as a model system and, when possible, concentrating on the influence that environmental factors (nutritional, metabolic, cellular, immunologic and others) have on them. The four major sections include: platelet interaction with tumor cells; a model for the study of cell-to-cell interaction; interaction of platelets with vessel walls; and platelet interactions with immune proteins.

  7. Remedial investigation/feasibility study of the Clinch River/Poplar Creek Operable Unit. Volume 2. Biota and representative concentrations of contaminants. Appendixes A, B, C, D

    SciTech Connect

    1996-03-01

    This report presents the findings of an investigation into contamination of the Clinch River and Poplar Creek near the U.S. Department of Energy`s (DOE`s) Oak Ridge Reservation (ORR) in eastern Tennessee. For more than 50 years, various hazardous and radioactive substances have been released to the environment as a result of operations and waste management activities at the ORR. In 1989, the ORR was placed on the National Priorities List (NPL), established and maintained under the federal Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). Under CERCLA, NPL sites must be investigated to determine the nature and extent of contamination at the site, assess the risk to human health and the environment posed by the site, and, if necessary, identify feasible remedial alternatives that could be used to clean the site and reduce risk. To facilitate the overall environmental restoration effort at the ORR, CERCLA activities are being implemented individually as distinct operable units (OU`s). This document is the combined Remedial Investigation and Feasibility Study Report for the Clinch River/Poplar Creek OU.

  8. Dependence of plasmin-mediated degradation of platelet adhesive receptors on temperature and Ca sup 2+

    SciTech Connect

    Winters, K.J.; Eisenberg, P.R.; Jaffe, A.S.; Santoro, S.A. )

    1990-10-15

    The effects of activation of plasminogen by streptokinase and tissue-type-plasminogen activator on platelet activation and the membrane glycoproteins (GPs) that mediate platelet adhesion and aggregation are not yet fully defined. To clarify effects on platelets during activation of plasminogen in vitro, we used monoclonal antibodies (MoAbs), flow cytometry, and platelets surface-labeled with {sup 125}I to characterize changes in receptors for fibrinogen (GPIIb-IIIa), von Willebrand factor (GPIb), and collagen (GPIa-IIa). Activation of plasminogen in plasma with pharmacologic concentrations of plasminogen activators did not degrade GPIIb-IIIa or GPIb, and caused only a modest decrease in GPIa. In washed platelets GPIIb-IIIa was extensively degraded by plasmin at 37{degrees}C in the absence of exogenous Ca{sup 2+}, conditions that destabilize the IIb-IIIa complex. Degradation of GPIb in washed platelets displayed a similar although less-marked dependence on temperature and the absence of Ca{sup 2+}. The binding of activation-specific MoAbs did not increase during activation of plasminogen in plasma. We conclude that during pharmacologic fibrinolysis, reported inhibition of platelet function in plasma is not due to degradation of platelet-adhesive receptors. In addition, platelet activation observed during thrombolytic therapy does not appear to be a direct consequence of plasminogen activation.

  9. Cell surface thiol isomerases may explain the platelet-selective action of S-nitrosoglutathione.

    PubMed

    Xiao, Fang; Gordge, Michael P

    2011-10-30

    S-nitrosoglutathione (GSNO) at low concentration inhibits platelet aggregation without causing vasodilation, suggesting platelet-selective nitric oxide delivery. The mechanism of this selectivity is unknown, but may involve cell surface thiol isomerases, in particular protein disulphide isomerase (csPDI) (EC 5.3.4.1). We have now compared csPDI expression and activity on platelets, endothelial cells and vascular smooth muscle cells, and the dependence on thiol reductase activity of these cell types for NO uptake from GSNO. csPDI expression was measured by flow cytometry and its reductase activity using the pseudosubstrate dieosin glutathione disulphide. This activity assay was adapted and validated for 96-well plate format. Flow cytometry revealed csPDI on all three cell types, but percentage positivity of expression was higher on platelets than on vascular cells. Consistent with this, thiol isomerase-related reductase activity was higher on platelets (P<0.01), and cellular activation (with either phorbol myristate acetate or ionomycin) increased csPDI activity on both platelets and smooth muscle cells, but not on endothelium. Intracellular NO delivery from GSNO was greater in platelets than in vascular cells (P<0.002), and was more sensitive to thiol isomerase inhibition using phenylarsine oxide (P<0.05). Increased surface thiol isomerase activity on platelets, compared with cells of the vascular wall, may explain the platelet-selective actions of GSNO and help define its antithrombotic potential. PMID:21642008

  10. Extract of feverfew inhibits interactions of human platelets with collagen substrates

    SciTech Connect

    Loesche, W.M.; Mazurov, A.V.; Heptinstall, S.; Groenewegen, W.A.; Repin, V.S.; Till, U.

    1987-12-01

    The interaction of platelets with surfaces coated with collagens of type III (C III) or IV (C IV) has been studied by measuring the deposition of /sup 51/Cr-labeled platelets and by scanning electron microscopy (SEM). Experiments were performed using platelet-rich plasma (PRP) and suspensions of gel-filtered platelets (GFP). Platelets were deposited on C III mainly as surface-bound aggregates. In contrast they were deposited on C IV mainly as spread forms of individual cells. Formation of aggregates on C III was more extensive for PRP than for GFP; in contrast platelet spreading on C IV was more extensive for GFP than for PRP. The effects of an extract of the plant feverfew on platelet-collagen interactions were determined. Feverfew extract inhibited the deposition of /sup 51/Cr-labeled platelets on both C III and C IV in a dose-dependent way. Similar concentrations of extract were needed to inhibit the formation of surface-bound aggregates and to inhibit platelet spreading in both PRP and GFP.

  11. 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

  12. Myeloperoxidase induces the priming of platelets.

    PubMed

    Kolarova, H; Klinke, A; Kremserova, S; Adam, M; Pekarova, M; Baldus, S; Eiserich, J P; Kubala, L

    2013-08-01

    The release of myeloperoxidase (MPO) from polymorphonuclear neutrophils is a hallmark of vascular inflammation and contributes to the pathogenesis of vascular inflammatory processes. However, the effects of MPO on platelets as a contributory mechanism in vascular inflammatory diseases remain unknown. Thus, MPO interaction with platelets and its effects on platelet function were examined. First, dose-dependent binding of MPO (between 1.7 and 13.8nM) to both human and mouse platelets was observed. This was in direct contrast to the absence of MPO in megakaryocytes. MPO was localized both on the surface of and inside platelets. Cytoskeleton inhibition did not prevent MPO localization inside the three-dimensional platelet structure. MPO peroxidase activity was preserved upon the MPO binding to platelets. MPO sequestered in platelets catabolized NO, documented by the decreased production of NO (on average, an approximately 2-fold decrease). MPO treatment did not affect the viability of platelets during short incubations; however, it decreased platelet viability after long-term storage for 7 days (an approximately 2-fold decrease). The activation of platelets by MPO was documented by an MPO-mediated increase in the expression of surface platelet receptors P-selectin and PECAM-1 (of about 5 to 20%) and the increased formation of reactive oxygen species (of about 15 to 200%). However, the activation was only partial, as MPO did not induce the aggregation of platelets nor potentiate platelet response to classical activators. Nor did MPO induce a significant release of the content of granules. The activation of platelets by MPO was connected with increased MPO-treated platelet interaction with polymorphonuclear leukocytes (an approximately 1.2-fold increase) in vitro. In conclusion, it can be suggested that MPO can interact with and activate platelets, which can induce priming of platelets, rather than the classical robust activation of platelets. This can contribute to the

  13. Activated platelets release sphingosine 1-phosphate and induce hypersensitivity to noxious heat stimuli in vivo

    PubMed Central

    Weth, Daniela; Benetti, Camilla; Rauch, Caroline; Gstraunthaler, Gerhard; Schmidt, Helmut; Geisslinger, Gerd; Sabbadini, Roger; Proia, Richard L.; Kress, Michaela

    2015-01-01

    At the site of injury activated platelets release various mediators, one of which is sphingosine 1-phosphate (S1P). It was the aim of this study to explore whether activated human platelets had a pronociceptive effect in an in vivo mouse model and whether this effect was based on the release of S1P and subsequent activation of neuronal S1P receptors 1 or 3. Human platelets were prepared in different concentrations (105/μl, 106/μl, 107/μl) and assessed in mice with different genetic backgrounds (WT, S1P1fl/fl, SNS-S1P1−/−, S1P3−/−). Intracutaneous injections of activated human platelets induced a significant, dose-dependent hypersensitivity to noxious thermal stimulation. The degree of heat hypersensitivity correlated with the platelet concentration as well as the platelet S1P content and the amount of S1P released upon platelet activation as measured with LC MS/MS. Despite the significant correlations between S1P and platelet count, no difference in paw withdrawal latency (PWL) was observed in mice with a global null mutation of the S1P3 receptor or a conditional deletion of the S1P1 receptor in nociceptive primary afferents. Furthermore, neutralization of S1P with a selective anti-S1P antibody did not abolish platelet induced heat hypersensitivity. Our results suggest that activated platelets release S1P and induce heat hypersensitivity in vivo. However, the platelet induced heat hypersensitivity was caused by mediators other than S1P. PMID:25954148

  14. 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

  15. Platelet and monocyte activity markers and mediators of inflammation in Takotsubo cardiomyopathy.

    PubMed

    Pirzer, Rainer; Elmas, Elif; Haghi, Dariusch; Lippert, Christiane; Kralev, Stefan; Lang, Siegfried; Borggrefe, Martin; Kälsch, Thorsten

    2012-03-01

    Patients with Takotsubo cardiomyopathy (TC) often present with symptoms similar to those of myocardial infarction (MI). We analyzed blood concentrations of mediators of inflammation and platelet- and monocyte-activity markers in patients with TC and MI for significant differences. Clinical data of patients with TC (n = 16) and acute MI (n = 16) were obtained. Serial blood samples were taken at the time of hospital admission (t(0)), after 2-4 days (t(1)) and after 4-7 weeks (t(2)), respectively. Plasma concentrations of interleukin (IL)-6, IL-7, soluble CD40 ligand (sCD40L), and monocyte chemotactic protein 1 (MCP-1) were determined with an ELISA. Tissue factor binding on monocytes, platelet-activation marker CD62P, platelet CD40-ligand (CD40L), and platelet-monocyte aggregates were measured using flow cytometry. Expression of CD62P on platelets and IL-6 plasma levels were significantly lower in patients with TC compared to MI at the time of hospital admission. IL-7 plasma levels were significantly elevated in patients with TC compared to patients with MI at 2-4 days after hospital admission. No significant differences were observed concerning sCD40L and MCP-1 plasma levels, tissue factor binding on monocytes, CD40L expression on platelets, and platelet-monocyte aggregates at any point in time. Our results indicate that inflammatory mediators and platelet-activity markers contribute to the differences in the pathogenesis of MI and TC. PMID:21416113

  16. Effect of Drotrecogin alfa (activated) on platelet receptor expression in vitro.

    PubMed

    Schuerholz, Tobias; Friedrich, Lars; Marx, Gernot; Kornau, Ines; Sümpelmann, Robert; Scheinichen, Dirk

    2007-08-01

    Thrombocytopenia is a common problem in critically ill patients, which is associated with increased mortality. Recently, Drotrecogin alfa (activated) (recombinant human activated protein C (APC)) was shown to reduce mortality in patients with severe sepsis. Only minimal effect of APC on coagulation markers was demonstrated. Nevertheless, low platelet count was identified as a risk factor for bleeding with use of this drug. We conducted this study to evaluate possible influence of APC on in vitro expression of platelet receptors at therapeutic and supra-therapeutic concentrations. Blood samples of volunteers and patients with severe sepsis were adjusted with APC to final concentrations of 0.045 microg mL(-1) APC (APC-45, therapeutic dose) and 0.225 microg mL(-1) APC (APC-225, five-fold therapeutic dose), respectively. The activation of platelets was mediated by two different agonists. APC had no significant influence on platelet activation, with or without stimulation at both concentrations. In group APC-225, CD62P showed a non-significant decrease. This in vitro study demonstrates that therapeutic plasma concentrations of Drotrecogin alfa (activated) have neither influence on expression of platelet activation markers nor on platelet-granulocyte complexes in blood of volunteers and patients with severe sepsis. Thus, a direct drug-platelet interaction seems unlikely. PMID:17654307

  17. 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.

  18. Clinical Applications of Platelet-Rich Plasma in Patellar Tendinopathy

    PubMed Central

    Jeong, D. U.; Lee, C.-R.; Lee, J. H.; Pak, J.; Kang, L.-W.; Jeong, B. C.

    2014-01-01

    Platelet-rich plasma (PRP), a blood derivative with high concentrations of platelets, has been found to have high levels of autologous growth factors (GFs), such as transforming growth factor-β (TGF-β), platelet-derived growth factor (PDGF), fibroblastic growth factor (FGF), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF). These GFs and other biological active proteins of PRP can promote tissue healing through the regulation of fibrosis and angiogenesis. Moreover, PRP is considered to be safe due to its autologous nature and long-term usage without any reported major complications. Therefore, PRP therapy could be an option in treating overused tendon damage such as chronic tendinopathy. Here, we present a systematic review highlighting the clinical effectiveness of PRP injection therapy in patellar tendinopathy, which is a major cause of athletes to retire from their respective careers. PMID:25136568

  19. Clinical applications of platelet-rich plasma in patellar tendinopathy.

    PubMed

    Jeong, D U; Lee, C-R; Lee, J H; Pak, J; Kang, L-W; Jeong, B C; Lee, S H

    2014-01-01

    Platelet-rich plasma (PRP), a blood derivative with high concentrations of platelets, has been found to have high levels of autologous growth factors (GFs), such as transforming growth factor-β (TGF-β), platelet-derived growth factor (PDGF), fibroblastic growth factor (FGF), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF). These GFs and other biological active proteins of PRP can promote tissue healing through the regulation of fibrosis and angiogenesis. Moreover, PRP is considered to be safe due to its autologous nature and long-term usage without any reported major complications. Therefore, PRP therapy could be an option in treating overused tendon damage such as chronic tendinopathy. Here, we present a systematic review highlighting the clinical effectiveness of PRP injection therapy in patellar tendinopathy, which is a major cause of athletes to retire from their respective careers. PMID:25136568

  20. α- and γ-mangostin cause shape changes, inhibit aggregation and induce cytolysis of rat platelets.

    PubMed

    Liu, Yingqiu; Park, Jung-Min; Chang, Kyung-Hwa; Chin, Young-Won; Lee, Moo-Yeol

    2015-10-01

    α- and γ-mangostin are natural xanthones isolated from mangosteen (Garcinia mangostana) and the major constituents responsible for the plant's diverse biological activities. In this study, the effects of α- and γ-mangostin on platelets were investigated based on their possible antiplatelet activity. Treatment of isolated platelets with α-mangostin resulted in attenuation of platelet aggregatory response to collagen, thrombin or ADP. Such antiaggregatory effects were concentration-dependent in ranges of 1-10 μM. Interestingly, α-mangostin alone induced shape changes in platelets at the same concentration, and higher levels, 25 and 50 μM caused platelet lysis. Similarly, γ-mangostin induced shape changes and inhibited aggregation at 2.5-25 μM, while 50 and 100 μM γ-mangostin exhibited cytotoxicity. Platelet shape change induced by α- and γ-mangostin was accompanied by increases in myosin light chain (MLC) phosphorylation. MLC phosphorylation and subsequent shape changes were prevented by pretreatment with Rho kinase (ROCK) inhibitor Y-27632, but not by the intracellular Ca(2+) chelating with BAPTA-AM and extracellular Ca(2+) removal. Cytolysis by both α- and γ-mangostin was abolished in the absence of extracellular Ca(2+). Taken together, α- and γ-mangostin have differential effects on platelets depending on their concentration, which includes inducing shape change, inhibiting aggregation and causing cytolysis. Platelet shape change is attributed to stimulation of the Rho/ROCK signaling pathway, while platelet lysis is presumably mediated by extracellular Ca(2+) influx. These results suggest that mangosteen consumption may have potential platelet effects, although the in vivo or clinical consequences have yet to be assessed. PMID:26343955

  1. Anti-platelet activity of erythro-(7S,8R)-7-acetoxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan from Myristica fragrans.

    PubMed

    Kang, Jung Won; Min, Byung-Sun; Lee, Jeong-Hyung

    2013-11-01

    Platelets play a critical role in pathogenesis of cardiovascular disorders and strokes. The inhibition of platelet function is beneficial for the treatment and prevention of these diseases. In this study, we investigated the anti-platelet activity of erythro-(7S,8R)-7-acetoxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan (EATN), a neolignan isolated from Myristica fragrans, using human platelets. EATN preferentially inhibited thrombin- and platelet-activating factor (PAF)-induced platelet aggregation without affecting platelet damage in a concentration-dependent manner with IC50 values of 3.2 ± 0.4 and 3.4 ± 0.3 μM, respectively. However, much higher concentrations of EATN were required to inhibit platelet aggregation induced by arachidonic acid. EATN also inhibited thrombin-induced serotonin and ATP release, and thromboxane B2 formation in human platelets. Moreover, EATN caused an increase in cyclic AMP (cAMP) levels and attenuated intracellular Ca(2+) mobilization in thrombin-activated human platelets. Therefore, we conclude that the inhibitory mechanism of EATN on platelet aggregation may increase cAMP levels and subsequently inhibit intracellular Ca(2+) mobilization by interfering with a common signaling pathway rather than by directly inhibiting the binding of thrombin or PAF to their receptors. This is the first report of the anti-platelet activity of EATN isolated from M. fragrans. PMID:23296979

  2. Response to platelet-activating factor in human platelets stored and aged in plasma. Decrease in aggregation, phosphoinositide turnover, and receptor affinity

    SciTech Connect

    Shukla, S.D.; Morrison, W.J.; Klachko, D.M.

    1989-07-01

    Human platelet concentrates were stored in polyolefin bags at 22 to 24 degrees C on a horizontal shaker for up to 8 days. At different intervals, aliquots of platelet-rich plasma (PRP) were removed aseptically and five variables, i.e., platelet counts, morphology, platelet-activating factor (PAF)-stimulated aggregation, phosphoinositide turnover, and (3H)PAF binding to platelet receptors, were studied. The number of platelets did not change during the 8 days of storage. Scanning electron microscopy of the platelets revealed a gradual morphologic change from biconcave flat discs to irregular, crenated forms. The PAF-induced aggregation of platelets declined with time of storage. A decrease to 50 percent of the Day 1 aggregatory response to PAF was evident on Day 2, and there was a further decline to about 20 percent by Day 6. Similarly, PAF receptor-coupled phosphoinositide turnover, as monitored by 32P incorporation into individual phosphoinositides, decreased dramatically with storage. After 2 to 3 days of storage, the phosphoinositide turnover was reduced to 50 percent of the original response, and it continued to decline to about 25 percent of original response by Day 5 or 6. The binding of (3H)PAF to washed human platelets indicated subtle changes between Days 2 and 4, which became more noticeable by Day 6. These results have raised the possibility of changes in the number of the receptors and/or their affinity for the ligand during storage. We conclude that although the number of platelets was maintained during storage for 8 days, a general deterioration of their responses to PAF occurred at the levels of cell surface receptor, transmembrane signaling (phosphoinositide turnover), and response (aggregation).

  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. 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.

  5. Induction and enhancement of platelet aggregation in vitro and in vivo by model polystyrene nanoparticles.

    PubMed

    Smyth, Erica; Solomon, Antonia; Vydyanath, Anupama; Luther, Pradeep K; Pitchford, Simon; Tetley, Teresa D; Emerson, Michael

    2015-05-01

    Nanoparticles (NPs) may come into contact with circulating blood elements including platelets following inhalation and translocation from the airways to the bloodstream or during proposed medical applications. Studies with model polystyrene latex nanoparticles (PLNPs) have shown that NPs are able to induce platelet aggregation in vitro suggesting a poorly defined potential mechanism of increased cardiovascular risk upon NP exposure. We aimed to provide insight into the mechanisms by which NPs may increase cardiovascular risk by determining the impact of a range of concentrations of PLNPs on platelet activation in vitro and in vivo and identifying the signaling events driving NP-induced aggregation. Model PLNPs of varying nano-size (50 and 100 nm) and surface chemistry [unmodified (uPLNP), amine-modified (aPLNP) and carboxyl-modified (cPLNP)] were therefore examined using in vitro platelet aggregometry and an established mouse model of platelet thromboembolism. Most PLNPs tested induced GPIIb/IIIa-mediated platelet aggregation with potencies that varied with both surface chemistry and nano-size. Aggregation was associated with signaling events, such as granule secretion and release of secondary agonists, indicative of conventional agonist-mediated aggregation. Platelet aggregation was associated with the physical interaction of PLNPs with the platelet membrane or internalization. 50 nm aPLNPs acted through a distinct mechanism involving the physical bridging of adjacent non-activated platelets leading to enhanced agonist-induced aggregation in vitro and in vivo. Our study suggests that should they translocate the pulmonary epithelium, or be introduced into the blood, NPs may increase the risk of platelet-driven events by inducing or enhancing platelet aggregation via mechanisms that are determined by their distinct combination of nano-size and surface chemistry. PMID:25030098

  6. The effects of siguazodan, a selective phosphodiesterase inhibitor, on human platelet function.

    PubMed Central

    Murray, K. J.; England, P. J.; Hallam, T. J.; Maguire, J.; Moores, K.; Reeves, M. L.; Simpson, A. W.; Rink, T. J.

    1990-01-01

    1. The effects of siguazodan (SK&F 94836) a selective phosphodiesterase (PDE) inhibitor with inotropic and vasodilator activity, were studied on human platelets. 2. Siguazodan selectively inhibited the major cyclic AMP-hydrolysing PDE in human platelet supernatants. The inhibited enzyme has been variously termed cyclic GMP-inhibited PDE or PDE-III. 3. In platelet-rich plasma (PRP), siguazodan inhibited U46619-induced aggregation more potently than that induced by ADP and collagen. Treatment of the PRP with aspirin had no effect on the potency of siguazodan. 4. In washed platelets, siguazodan increased cyclic AMP levels and reduced cytoplasmic free calcium [( Ca2+]i). ADP decreased the ability of siguazodan to raise cyclic AMP and this may explain its lower potency in inhibiting responses to ADP. 5. Siguazodan has anti-platelet actions over the same concentration range that it is an inotrope and vasodilator. PMID:2158847

  7. Calcium handling by platelets from normal and malignant hyperthermia-susceptible pigs

    SciTech Connect

    Miller, K.E.; Brooks, R.R.; Bonk, K.R.; Carpenter, J.F. )

    1991-01-01

    Platelets from normal and malignant hyperthermia (MH)-susceptible pigs were evaluated for differences in {sup 45}calcium uptake in the absence or presence of caffeine, halothane, or halothane and caffeine together. There were no statistically significant differences in basal or halothane-inhibited calcium uptake by platelets from either source. There was a small statistically significant difference in calcium uptake between platelets from normal and MH-susceptible pigs in the presence of 16 mM caffeine and 0.5% halothane. Calcium uptake by platelets from one pedigree of MH-susceptible pigs were stimulated in a concentration-dependent manner by caffeine. These data suggest that exposure of platelets to caffeine may have potential for identifying MH-susceptibility.

  8. Characterization of the Human Platelet α-Adrenergic Receptor

    PubMed Central

    Alexander, R. Wayne; Cooper, Barry; Handin, Robert I.

    1978-01-01

    Human platelets aggregate and undergo a release reaction when incubated with catecholamines. Indirect evidence indicates that these events are mediated through α-adrenergic receptors. We used [3H]dihydroergocryptine, an α-adrenergic antagonist, to identify binding sites on platelets that have the characteristics of α-adrenergic receptors. Catecholamines compete for the binding sites in a stereo-specific manner with the potency series of (−) epinephrine > (−) norepinephrine > (±) phenylephrine > (−) isoproterenol. The dissociation constant (Kd) of (−) epinephrine is 0.34 μM. Binding is saturable using a platelet particulate fraction but not with intact platelets. There are 0.130 pmol binding sites per milligram protein in fresh platelet membranes. This number represents approximately 100 binding sites per platelet. The Kd for [3H]-dihydroergocryptine was 0.003−0.01 μM. The α-adrenergic antagonist phentolamine (Kd = 0.0069 μM) was much more potent than the β-adrenergic antagonist (±) propranolol (Kd = 27 μM) in competing for the binding sites. The binding data were correlated with catecholamine-induced platelet aggregation and inhibition of basal and prostaglandin E1-stimulated adenylate cyclase. (−) Epinephrine was more potent than (−) norepinephrine in producing aggregation whereas (−) isoproterenol was ineffective. The threshold dose for inducing aggregation by (−) epinephrine was 0.46 μM. Phentolamine and dihydroergocyrptine blocked this response, whereas (±) propranolol had no effect. (−) Epinephrine and (−) norepinephrine inhibited basal and prostaglandin E1-stimulated adenylate cyclase in a dose-related manner. The concentration of (−) epinephrine inhibiting adenylate cyclase 50% was 0.7 μM. This inhibition was also blocked by phentolamine and dihydroergocryptine but not by (±) propranolol. The specificity of binding and the close correlation with α-adrenergic receptor-mediated biochemical and physiological responses

  9. Platelet storage media change the expression characteristics of the platelet-derived microparticles.

    PubMed

    Yari, Fatemeh; Azadpour, Shima; Shiri, Reza

    2014-09-01

    Activated platelets shed microparticles in vivo and definitely in vitro upon aging under storage. Studies about the platelet-derived microparticles (PMPs) produced in different storage media of PC were very limited. The aim of this research was to compare some surface molecules of these microvesicles in dissimilar microenvironments; plasma and the candidate medium for the platelet concentrate, Composol. Thirty units of PCs were prepared from Iranian Blood Transfusion Organization. Each unit was divided into two portions. In one of the portions, plasma was replaced with Composol using a connecting device instrument. MPs were isolated from PC and the levels of PS exposure (the annexin-binding capacity) and binding to vWF were surveyed on their surface using ELISA and flow cytometry techniques. The levels of PS exposure were increased on MPs during 7 days storage in the both media but the differences were not significant (P value >0.05). In addition, binding of PMP to vWF was declined during storage. The binding capabilities of PMP were significantly higher in Composol than that of plasma at the day 4 or 7 of storage (P value = 001). It seemed that the binding of PMPs to vWF was affected from the storage media of PC (plasma and Composol) but PS exposure was not affected from the type of storage media. PMID:25114402

  10. Genetics Home Reference: gray platelet syndrome

    MedlinePlus

    ... to play a role in the formation of alpha-granules, which are sacs inside platelets that contain ... injury that causes bleeding, the proteins stored in alpha-granules help platelets stick to one another to ...

  11. [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

  12. Effect of photodynamic therapy on mouse platelets

    NASA Astrophysics Data System (ADS)

    Zhou, Chuannong; Chi, Shunji; Deng, Jinsheng; Zhang, Hua; Liang, Junlin; Ha, Xian-wen

    1993-06-01

    Normal mice received hematoporphyrin derivative (HpD) i.v. prior to red light irradiation and the platelet-rich plasma was prepared and irradiated by red light. The platelets were processed for EM examination and stereological analysis. It was shown the 16 hrs after irradiation almost all platelets were necrotized; 8 hours after irradiation about one fourth of the platelets were necrotized and the remaining were considerably damaged. Immediately after irradiation a small number of platelets became necrotic and most other platelets were swollen and deformated, showing significantly increased mean area, perimeter and short axis, and mean cell volume and cell surface area. The findings indicate that platelets are highly sensitive to PDT action and can be directly and rapidly damaged by PDT even in the absence of vascular endothelial cells. The early platelet photoactivation may play an important role in the initiation of early vascular damage and microcirculatory alterations induced by PDT in vivo.

  13. CD8+ T cells induce platelet clearance in the liver via platelet desialylation in immune thrombocytopenia

    PubMed Central

    Qiu, Jihua; Liu, Xuena; Li, Xiaoqing; Zhang, Xu; Han, Panpan; Zhou, Hai; Shao, Linlin; Hou, Yu; Min, Yanan; Kong, Zhangyuan; Wang, Yawen; Wei, Yu; Liu, Xinguang; Ni, Heyu; Peng, Jun; Hou, Ming

    2016-01-01

    In addition to antiplatelet autoantibodies, CD8+ cytotoxic T lymphocytes (CTLs) play an important role in the increased platelet destruction in immune thrombocytopenia (ITP). Recent studies have highlighted that platelet desialylation leads to platelet clearance via hepatocyte asialoglycoprotein receptors (ASGPRs). Whether CD8+ T cells induce platelet desialylation in ITP remains unclear. Here, we investigated the cytotoxicity of CD8+ T cells towards platelets and platelet desialylation in ITP. We found that the desialylation of fresh platelets was significantly higher in ITP patients with positive cytotoxicity of CD8+ T cells than those without cytotoxicity and controls. In vitro, CD8+ T cells from ITP patients with positive cytotoxicity induced significant platelet desialylation, neuraminidase-1 expression on the platelet surface, and platelet phagocytosis by hepatocytes. To study platelet survival and clearance in vivo, CD61 knockout mice were immunized and their CD8+ splenocytes were used. Platelets co-cultured with these CD8+ splenocytes demonstrated decreased survival in the circulation and increased phagocytosis in the liver. Both neuraminidase inhibitor and ASGPRs competitor significantly improved platelet survival and abrogated platelet clearance caused by CD8+ splenocytes. These findings suggest that CD8+ T cells induce platelet desialylation and platelet clearance in the liver in ITP, which may be a novel mechanism of ITP. PMID:27321376

  14. CD8(+) T cells induce platelet clearance in the liver via platelet desialylation in immune thrombocytopenia.

    PubMed

    Qiu, Jihua; Liu, Xuena; Li, Xiaoqing; Zhang, Xu; Han, Panpan; Zhou, Hai; Shao, Linlin; Hou, Yu; Min, Yanan; Kong, Zhangyuan; Wang, Yawen; Wei, Yu; Liu, Xinguang; Ni, Heyu; Peng, Jun; Hou, Ming

    2016-01-01

    In addition to antiplatelet autoantibodies, CD8(+) cytotoxic T lymphocytes (CTLs) play an important role in the increased platelet destruction in immune thrombocytopenia (ITP). Recent studies have highlighted that platelet desialylation leads to platelet clearance via hepatocyte asialoglycoprotein receptors (ASGPRs). Whether CD8(+) T cells induce platelet desialylation in ITP remains unclear. Here, we investigated the cytotoxicity of CD8(+) T cells towards platelets and platelet desialylation in ITP. We found that the desialylation of fresh platelets was significantly higher in ITP patients with positive cytotoxicity of CD8(+) T cells than those without cytotoxicity and controls. In vitro, CD8(+) T cells from ITP patients with positive cytotoxicity induced significant platelet desialylation, neuraminidase-1 expression on the platelet surface, and platelet phagocytosis by hepatocytes. To study platelet survival and clearance in vivo, CD61 knockout mice were immunized and their CD8(+) splenocytes were used. Platelets co-cultured with these CD8(+) splenocytes demonstrated decreased survival in the circulation and increased phagocytosis in the liver. Both neuraminidase inhibitor and ASGPRs competitor significantly improved platelet survival and abrogated platelet clearance caused by CD8(+) splenocytes. These findings suggest that CD8(+) T cells induce platelet desialylation and platelet clearance in the liver in ITP, which may be a novel mechanism of ITP. PMID:27321376

  15. New treatment for low platelets.

    PubMed

    Grodeck, B

    1995-01-01

    The Food and Drug Administration (FDA) recently approved WinRho SD, a new treatment for immune thrombocytopenic purpura (ITP). A clinical trial in children with acute ITP found that WinRho SD is as effective as IVIG or prednisone, but less expensive and dramatically easier to administer. WinRho SD is the first polyclonal antibody product shown to increase platelets in ITP patients. Platelets usually rise within one to two days and peak within seven to fourteen days after initial therapy. On average, platelet levels are maintained for approximately thirty days. Each year, 50,000 people nationally suffer from ITP as a complication of HIV infection, while another 18,000 manifest the disease as a primary condition. PMID:11362579

  16. Short fungal fractions of β-1,3 glucans affect platelet activation.

    PubMed

    Vancraeyneste, Hélène; Charlet, Rogatien; Guerardel, Yann; Choteau, Laura; Bauters, Anne; Tardivel, Meryem; François, Nadine; Dubuquoy, Laurent; Soloviev, Dmitry; Poulain, Daniel; Sendid, Boualem; Jawhara, Samir

    2016-09-01

    Platelets are capable of binding, aggregating, and internalizing microorganisms, which enhances the elimination of pathogens from the blood. The yeast Candida albicans is a pathobiont causing life-threatening invasive infections. Its cell wall contains β-1,3 glucans that are known to trigger a wide range of host cell activities and to circulate during infection. We studied the effect of β-1,3 glucan fractions (BGFs) consisting of diglucosides (Glc2), tetraglucosides (Glc4), and pentaglucosides (Glc5) on human platelets, their mechanisms of action, and their possible impact on host defenses. The effect of BGFs on the coagulation process was determined by measuring thrombin generation. Platelets pretreated with BGFs were analyzed in terms of activation, receptor expression, aggregation, and adhesion to neutrophils and to C. albicans The results show that BGFs affected the endogenous thrombin potential in a concentration-dependent manner. For platelet activation, BGFs at a low concentration (2 μmol/l) reduced ATP release and prevented the phosphorylation of protein kinase C. BGFs diminished the expression of P-selectin and the activation of αIIbβ3 BGFs decreased platelet aggregation and the interaction between thrombin-stimulated platelets and neutrophils, fibrinogen, and C. albicans GLc5 decreased ATP release and TGF-β1 production in response to TLR4 upregulation in thrombin-stimulated platelets, but TLR4 blockage abolished the effect of BGFs on platelets. This study provides evidence that fungal pentaglucosides modulate platelet activity mediated via TLR4 stimulation and reduce platelet-neutrophil interaction. PMID:27288438

  17. Arachidonate metabolism, 5-hydroxytryptamine release and aggregation in human platelets activated by palmitaldehyde acetal phosphatidic acid.

    PubMed Central

    Brammer, J. P.; Maguire, M. H.

    1984-01-01

    Palmitaldehyde acetal phosphatidic acid ( PGAP ) caused dose-dependent aggregation of human platelets resuspended in modified Tyrode medium, with a threshold concentration of 0.5-1 microM and an EC50 of 4 microM. Concentrations of PGAP which elicited biphasic irreversible aggregation concomitantly induced formation of 1.02 +/- 0.029 nmol (mean +/- s.e. mean) of malondialdehyde (MDA) per 10(9) platelets and caused release of 58 +/- 2.8% of platelet [14C]-5-hydroxytryptamine ([14C]-5-HT) from prelabelled platelets; no MDA formation or [14C]-5-HT release occurred at lower doses of PGAP which elicited only monophasic reversible aggregation. Adenosine 5'-pyrophosphate (ADP)-induced platelet activation resulted in formation of 0.344 +/- 0.004 nmol of MDA per 10(9) platelets in association with irreversible aggregation and 49.1 +/- 1% release of [14C]-5-HT. Mepacrine, a phospholipase A2 inhibitor, at 2.5 microM reduced PGAP -induced MDA formation and [14C]-5-HT release by the resuspended platelets without affecting irreversible aggregation; higher concentrations of mepacrine abolished all three responses. Chlorpromazine, a calmodulin antagonist, similarly inhibited PGAP -induced MDA formation and irreversible aggregation, and at 100 microM abolished monophasic aggregation. The cyclo-oxygenase inhibitor indomethacin caused a concentration-dependent reduction of PGAP -induced MDA formation by resuspended human platelets without significantly inhibiting [14C]-5-HT release or irreversible aggregation; concentrations (greater than or equal to 1.75 microM) which inhibited MDA formation by more than 94% abolished [14C]-5-HT release, and converted second phase irreversible aggregation to an extensive reversible response. 2-Methylthioadenosine 5'-phosphate (2 methylthio-AMP), an ADP antagonist, inhibited PGAP -induced MDA formation, [14C]-5-HT release and second phase aggregation in the human platelet suspensions in a parallel, concentration-dependent manner; at 9.4 microM 2

  18. 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.

  19. A side-by-side evaluation of four platelet-counting instruments.

    PubMed

    Dalton, W T; Bollinger, P; Drewinko, B

    1980-08-01

    The performances of four instruments for counting platelets were evaluated in a side-by-side study: the Haema-Count MK-4/HC, an electronic impedance instrument that counts platelets in platelet-rich plasma; the Ultra-Flo 100, and the Coulter Counter Model S-Plus, electronic impedance instruments that count platelets in the presence of intact erythrocytes; and the AutoCounter, an optical instrument that counts platelets in the presence of lysed erythrocytes. The Ultra-Flo 100 and the S-Plus showed the best within-run precision, and all four instruments were considerably more precise than manual platelet counting, especially at low levels of platelet count. The four instruments were all linear in the ranges tested (5 to 650 x 10(9)/or greater), and sample carry-over was less than 0.7% for each. A noteworthy finding was that the erythrocyte concentration of the blood samples affected the displayed platelet count of the S-Plus and, to a lesser extent, that of the AutoCounter, in a predictable way, whereas it did not greatly affect the displayed count of the Ultra-Flo 100. In addition to differences in quality of performances, the four instruments differed considerably in speed and ease of operation and in cost. PMID:7405890

  20. Platelet Proteome Analysis Reveals Integrin-dependent Aggregation Defects in Patients with Myelodysplastic Syndromes*

    PubMed Central

    Fröbel, Julia; Cadeddu, Ron-Patrick; Hartwig, Sonja; Bruns, Ingmar; Wilk, Christian M.; Kündgen, Andrea; Fischer, Johannes C.; Schroeder, Thomas; Steidl, Ulrich G.; Germing, Ulrich; Lehr, Stefan; Haas, Rainer; Czibere, Akos

    2013-01-01

    Bleeding complications are a significant clinical problem in patients with myelodysplastic syndromes even at sufficient platelet counts (>50,000/μl). However, the underlying pathology of this hemorrhagic diathesis is still unknown. Here, we analyzed the platelet proteome of patients with myelodysplastic syndromes by quantitative two-dimensional difference gel electrophoresis followed by mass spectrometric protein identification. Proteins identified with lower concentrations, such as Talin-1, Vinculin, Myosin-9, Filmain-A, and Actin play critical roles in integrin αIIbβ3 signaling and thus platelet aggregation. Despite normal agonist receptor expression, calcium flux, and granule release upon activation, the activation capacity of integrin αIIbβ3 was diminished in myelodysplastic syndrome platelets. Förster resonance energy transfer analysis showed a reduced co-localization of Talin-1 to the integrin's β3-subunit, which is required for receptor activation and fibrinogen binding. In addition, platelet spreading on immobilized fibrinogen was incomplete, and platelet aggregation assays confirmed a general defect in integrin-dependent platelet aggregation in patients with myelodysplastic syndromes. Our data provide novel aspects on the molecular pathology of impaired platelet function in myelodysplastic syndromes and suggest a mechanism of defective integrin αIIbβ3 signaling that may contribute to the hemorrhagic diathesis observed in these patients. PMID:23382103

  1. Megakaryocyte rupture for acute platelet needs

    PubMed Central

    Stritt, Simon

    2015-01-01

    Circulating platelets were thought to arise solely from the protrusion and fragmentation of megakaryocyte cytoplasm. Now, Nishimura et al. (2015. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201410052) show that platelet release from megakaryocytes can be induced by interleukin-1α (IL-1α) via a new rupture mechanism, which yields higher platelet numbers, occurs independently of the key regulator of megakaryopoiesis thrombopoietin, and may occur during situations of acute platelet need. PMID:25963815

  2. Megakaryocyte rupture for acute platelet needs.

    PubMed

    Nieswandt, Bernhard; Stritt, Simon

    2015-05-11

    Circulating platelets were thought to arise solely from the protrusion and fragmentation of megakaryocyte cytoplasm. Now, Nishimura et al. (2015. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201410052) show that platelet release from megakaryocytes can be induced by interleukin-1α (IL-1α) via a new rupture mechanism, which yields higher platelet numbers, occurs independently of the key regulator of megakaryopoiesis thrombopoietin, and may occur during situations of acute platelet need. PMID:25963815

  3. Platelet Activation: The Mechanisms and Potential Biomarkers

    PubMed Central

    Yun, Seong-Hoon; Sim, Eun-Hye; Goh, Ri-Young; Park, Joo-In

    2016-01-01

    Beyond hemostasis and thrombosis, an increasing number of studies indicate that platelets play an integral role in intercellular communication, mediating inflammatory and immunomodulatory activities. Our knowledge about how platelets modulate inflammatory and immunity has greatly improved in recent years. In this review, we discuss recent advances in the pathways of platelet activation and potential application of platelet activation biomarkers to diagnosis and prediction of disease states. PMID:27403440

  4. 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

  5. Multiscale model of platelet translocation and collision

    NASA Astrophysics Data System (ADS)

    Wang, Weiwei; Mody, Nipa A.; King, Michael R.

    2013-07-01

    The tethering of platelets on the injured vessel surface mediated by glycoprotein Ibα (GPIbα) - Von Willebrand factor (vWF) bonds, as well as the interaction between flowing platelets and adherent platelets, are two key events that take place immediately following blood vessel injury. This early-stage platelet deposition and accumulation triggers the initiation of hemostasis, a self-defensive mechanism to prevent the body from excessive blood loss. To understand and predict this complex process, one must integrate experimentally determined information on the mechanics and biochemical kinetics of participating receptors over very small time frames (1-1000 μs) and length scales (10-100 nm), to collective phenomena occurring over seconds and tens of microns. In the present study, a unique three dimensional multiscale computational model, Platelet Adhesive Dynamics (PAD), was applied to elucidate the unique physics of (i) a non-spherical, disk-shaped platelet interacting and tethering onto the damaged vessel wall followed by (ii) collisional interactions between a flowing platelet with a downstream adherent platelet. By analyzing numerous simulations under different physiological conditions, we conclude that the platelet's unique spheroid-shape provides heterogeneous, orientation-dependent translocation (rolling) behavior which enhances cell-wall interactions. We also conclude that platelet-platelet near field interactions are critical for cell-cell communication during the initiation of microthrombi. The PAD model described here helps to identify the physical factors that control the initial stages of platelet capture during this process.

  6. New Horizons in Platelets Flow Cytometry

    PubMed Central

    Saboor, Muhammad; Moinuddin, Moinuddin; Ilyas, Samina

    2013-01-01

    Platelet flow cytometry is an emerging tool in diagnostic and therapeutic hematology. It is eminently suited to study the expression of platelet surface receptors both qualitatively as well as quantitatively. It can serve as a useful marker for the documentation of in vivo platelet activation, and thus, fore-warn the risk of thromboembolism in patients with diabetes mellitus, coronary syndromes, peripheral vascular diseases, and pre-eclampsia. This technique can also be extended to study and compare the effect of various antiplatelet drugs on the level of activation of platelets and to establish any dose-effect relationship of these drugs. Topographical localization of platelet granules and study of platelet-platelet and platelet-leukocyte interaction is also possible by this procedure. All these parameters serve as pointers towards the presence of activated platelets in the circulation with its thromboembolic consequences. This is a simple reliable and cost effective technique which has a wide application in the diagnosis of various inherited and acquired platelet disorders. Study of platelet cluster of differentiation (CD) markers in various inherited disorders i.e. Bernard Soulier’s disease, von Willebrand disease, Glanzman’s disease, and Grey platelet syndrome may help categories the molecular lesions in these oft under-studied disorders. PMID:23983579

  7. Anti-platelet and anti-thrombogenic effects of shikimic acid in sedentary population.

    PubMed

    Veach, Daniel; Hosking, Holly; Thompson, Kiara; Santhakumar, Abishek Bommannan

    2016-08-10

    This ex vivo study was performed to evaluate the anti-platelet and anti-thrombogenic potential of shikimic acid (SA), a plant phenolic metabolite. Fasting blood samples were collected from 22 sedentary participants to analyse the effect of varying concentrations of SA (0.1 mM, 0.2 mM, 0.5 mM, 1 mM and 2 mM) on platelet surface-marker expression, platelet aggregation and biomarkers of thrombogenesis. Monocyte-platelet aggregates (CD14/CD42b) and platelet endothelial cell adhesion molecule-1 (PECAM-1 or CD31), effective indicators of thrombus formation were evaluated. Procaspase-activating compound 1 (PAC-1) and P-selectin or CD62P were used to assess platelet activation-related thrombogenesis. Adenosine diphosphate (ADP) was used to stimulate the P2Y1/P2Y12 pathway of platelet activation to mimic the in vivo thrombogenic pathway. Platelet aggregation studies utilised both ADP and collagen as exogenous platelet agonists to target both P2Y1/P2Y12 and GPVI pathways of thrombus formation. It was observed with flow cytometry that SA produced a significant antiplatelet effect on PAC-1 (p = 0.03 at 2 mM) and CD62P (p = 0.017, p = 0.036 at 1 mM and 2 mM respectively) expression in addition to lowering monocyte-platelet aggregate formation (p = 0.013, p < 0.01 and p < 0.01 at 0.5 mM, 1 mM and 2 mM respectively). SA at 1 mM concentration reduced PECAM-1 expression (p = 0.035), signifying a reduction to endothelial leucocyte migration during thrombus growth. SA did not demonstrate a platelet aggregation inhibitory effect by targeting the GPVI collagen pathway but reduced ADP induced platelet aggregation at 2 mM concentration (p < 0.01 at 2 mM). The results suggest that SA, an active metabolite of polyphenol-rich food intake, could play an important role in reducing platelet activation, aggregation related thrombus formation and biomarkers of thrombogenesis in sedentary individuals. PMID:27480079

  8. Exploratory studies of extended storage of apheresis platelets in a platelet additive solution (PAS).

    PubMed

    Slichter, Sherrill J; Corson, Jill; Jones, Mary Kay; Christoffel, Todd; Pellham, Esther; Bailey, S Lawrence; Bolgiano, Doug

    2014-01-01

    To evaluate the poststorage viability of apheresis platelets stored for up to 18 days in 80% platelet additive solution (PAS)/20% plasma, 117 healthy subjects donated platelets using the Haemonetics MCS+, COBE Spectra (Spectra), or Trima Accel (Trima) systems. Control platelets from the same subjects were compared with their stored test PAS platelets by radiolabeling their stored and control platelets with either (51)chromium or (111)indium. Trima platelets met Food and Drug Administration poststorage platelet viability criteria for only 7 days vs almost 13 days for Haemonetics platelets; ie, platelet recoveries after these storage times averaged 44 ± 3% vs 49 ± 3% and survivals were 5.4 ± 0.3 vs 4.6 ± 0.3 days, respectively. The differences in storage duration are likely related to both the collection system and the storage bag. The Spectra and Trima platelets were hyperconcentrated during collection, and PAS was added, whereas the Haemonetics platelets were elutriated with PAS, which may have resulted in less collection injury. When Spectra and Trima platelets were stored in Haemonetics' bags, poststorage viability was significantly improved. Platelet viability is better maintained in vitro than in vivo, allowing substantial increases in platelet storage times. However, implementation will require resolution of potential bacterial overgrowth during storage. PMID:24258816

  9. Suboptimal Activation of Protease-activated Receptors Enhances α2β1 Integrin-mediated Platelet Adhesion to Collagen*

    PubMed Central

    Marjoram, Robin J.; Voss, Bryan; Pan, Yumei; Dickeson, S. Kent; Zutter, Mary M.; Hamm, Heidi E.; Santoro, Samuel A.

    2009-01-01

    Thrombin and fibrillar collagen are potent activators of platelets at sites of vascular injury. Both agonists cause platelet shape change, granule secretion, and aggregation to form the primary hemostatic plug. Human platelets express two thrombin receptors, protease-activated receptors 1 and 4 (PAR1 and PAR4) and two collagen receptors, the α2β1 integrin (α2β1) and the glycoprotein VI (GPVI)/FcRγ chain complex. Although these receptors and their signaling mechanisms have been intensely studied, it is not known whether and how these receptors cooperate in the hemostatic function of platelets. This study examined cooperation between the thrombin and collagen receptors in platelet adhesion by utilizing a collagen-related peptide (α2-CRP) containing the α2β1-specific binding motif, GFOGER, in conjunction with PAR-activating peptides. We demonstrate that platelet adhesion to α2-CRP is substantially enhanced by suboptimal PAR activation (agonist concentrations that do not stimulate platelet aggregation) using the PAR4 agonist peptide and thrombin. The enhanced adhesion induced by suboptimal PAR4 activation was α2β1-dependent and GPVI/FcRγ-independent as revealed in experiments with α2β1- or FcRγ-deficient mouse platelets. We further show that suboptimal activation of other platelet Gq-linked G protein-coupled receptors (GPCRs) produces enhanced platelet adhesion to α2-CRP. The enhanced α2β1-mediated platelet adhesion is controlled by phospholipase C (PLC), but is not dependent on granule secretion, activation of αIIbβ3 integrin, or on phosphoinositol-3 kinase (PI3K) activity. In conclusion, we demonstrate a platelet priming mechanism initiated by suboptimal activation of PAR4 or other platelet Gq-linked GPCRs through a PLC-dependent signaling cascade that promotes enhanced α2β1 binding to collagens containing GFOGER sites. PMID:19815553

  10. Aggregation efficiency of activated normal or fixed platelets in a simple shear field: effect of shear and fibrinogen occupancy.

    PubMed Central

    Xia, Z; Frojmovic, M M

    1994-01-01

    Shear rate can affect protein adsorption and platelet aggregation by regulating both the collision frequency and the capture efficiency (alpha). These effects were evaluated in well defined shear field in a micro-couette for shear rate G = 10 - 1000 s-1. The rate of protein binding was independent of G, shown for adsorption of albumin to latex beads and PAC1 to activated platelets. The initial aggregation rate for ADP-activated platelets in citrated platelet-rich plasma followed second order kinetics at the initial platelet concentrations between 20,000 and 60,000/microliters. alpha values, which dropped nearly fivefold for a 10-fold increase in G, were approximately proportional to G-1, contrary to a minor drop predicted by the theory that includes protein cross-bridging. Varying ADP concentration did not change alpha of maximally activated platelet subpopulations, suggesting that aggregation between unactivated and activated platelets is negligible. Directly blocking the unoccupied but activated GPIIb-IIIa receptors without affecting pre-bound Fg on "RGD"-activated, fixed platelets (AFP) by GRGDSP or Ro 43-5054 eliminated aggregation, suggesting that cross-bridging of GPIIb-IIIa on adjacent platelets by fibrinogen mediates aggregation. Alpha for AFP remained maximal (approximately 0.24) over 25-75% Fg occupancy, otherwise decreasing rapidly, with a half-maximum occurring at around 2% occupancy, suggesting that very few bound Fg were required to cause significant aggregation. Images FIGURE 1 PMID:8075353

  11. Interaction of the Paf antagonist WEB 2086 and its hetrazepine analogues with human platelets and endothelial cells.

    PubMed Central

    Korth, R.; Hirafuji, M.; Keraly, C. L.; Delautier, D.; Bidault, J.; Benveniste, J.

    1989-01-01

    1. Intact platelets and confluent human umbilical vein endothelial cells bound [3H]-Paf-acether (platelet activating factor, [3H]-Paf) at 20 degrees C in the presence of 0.25% (w/v) bovine serum albumin (BSA). 2. [3H]-Paf binding to platelets was inhibited in a concentration-dependent manner by WEB 2086. An excess of WEB 2086 indicated the presence of specific, saturable Paf binding which reached a maximum of 28.3 +/- 3.7 fmol [3H]-Paf per 5 x 10(7) platelets. In platelets, different hetrazepines (WEB 2098, 2105, but not 2118) also inhibited [3H]-Paf binding in a concentration-dependent manner. 3. WEB 2086 partially displaced platelet-bound [3H]-Paf in a concentration-dependent manner reaching a plateau at 400 nM WEB 2086. No further displacement was observed when WEB 2086 and an excess of unlabelled Paf were added together. 4. The hetrazepines inhibited platelet aggregation. Platelet aggregation IC50 values correlated well with the IC50 values of the hetrazepines against [3H]-Paf binding (r2 = 0.99). WEB 2086 shifted the Paf dose-response curve rightwards in a parallel manner. Tested against platelet aggregation the pA2 obtained for WEB 2086 was 7.9. 5. WEB 2086 inhibited [3H]-Paf binding to endothelial cells in a concentration-dependent manner. WEB 2086 also inhibited the Paf-mediated cytosolic calcium increase in endothelial cells with an IC50 value of 23.1 +/- 10.4 nM as compared with an IC50 of 21.6 +/- 10.4 nM WEB 2086 for platelet aggregation. 6. These results demonstrate an inhibition of [3H]-Paf binding to platelets and endothelial cells by different hetrazepines, most probably at the Paf receptor level. PMID:2555017

  12. Mechanisms of platelet-mediated liver regeneration.

    PubMed

    Lisman, Ton; Porte, Robert J

    2016-08-01

    Platelets have multiple functions beyond their roles in thrombosis and hemostasis. Platelets support liver regeneration, which is required after partial hepatectomy and acute or chronic liver injury. Although it is widely assumed that platelets stimulate liver regeneration by local excretion of mitogens stored within platelet granules, definitive evidence for this is lacking, and alternative mechanisms deserve consideration. In-depth knowledge of mechanisms of platelet-mediated liver regeneration may lead to new therapeutic strategies to treat patients with failing regenerative responses. PMID:27297793

  13. Splenic release of platelets contributes to increased circulating platelet size and inflammation after myocardial infarction.

    PubMed

    Gao, Xiao-Ming; Moore, Xiao-Lei; Liu, Yang; Wang, Xin-Yu; Han, Li-Ping; Su, Yidan; Tsai, Alan; Xu, Qi; Zhang, Ming; Lambert, Gavin W; Kiriazis, Helen; Gao, Wei; Dart, Anthony M; Du, Xiao-Jun

    2016-07-01

    Acute myocardial infarction (AMI) is characterized by a rapid increase in circulating platelet size but the mechanism for this is unclear. Large platelets are hyperactive and associated with adverse clinical outcomes. We determined mean platelet volume (MPV) and platelet-monocyte conjugation (PMC) using blood samples from patients, and blood and the spleen from mice with AMI. We further measured changes in platelet size, PMC, cardiac and splenic contents of platelets and leucocyte infiltration into the mouse heart. In AMI patients, circulating MPV and PMC increased at 1-3 h post-MI and MPV returned to reference levels within 24 h after admission. In mice with MI, increases in platelet size and PMC became evident within 12 h and were sustained up to 72 h. Splenic platelets are bigger than circulating platelets in normal or infarct mice. At 24 h post-MI, splenic platelet storage was halved whereas cardiac platelets increased by 4-fold. Splenectomy attenuated all changes observed in the blood, reduced leucocyte and platelet accumulation in the infarct myocardium, limited infarct size and alleviated cardiac dilatation and dysfunction. AMI-induced elevated circulating levels of adenosine diphosphate and catecholamines in both human and the mouse, which may trigger splenic platelet release. Pharmacological inhibition of angiotensin-converting enzyme, β1-adrenergic receptor or platelet P2Y12 receptor reduced platelet abundance in the murine infarct myocardium albeit having diverse effects on platelet size and PMC. In conclusion, AMI evokes release of splenic platelets, which contributes to the increase in platelet size and PMC and facilitates myocardial accumulation of platelets and leucocytes, thereby promoting post-infarct inflammation. PMID:27129192

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

    SciTech Connect

    Mezzano, D.; Hwang, K.; Catalano, P.; Aster, R.H.

    1981-01-01

    Following infusion of 51Cr-labeled autologous platelets into normal subjects, high-density (HD) and low-density (LD) platelet cohorts were isolated by prolonged centrifugation in isosmotic arabino-galactan (Stractan). Specific radio-activity of LD platelets declined rapidly post-infusion (T1/2 . 1.5 days), but specific radioactivity of HD platelets remained constant or increased over a 3--4-day period and gradually declined for 6--7 days thereafter. These differences were exaggerated when platelet cohorts enriched in LD or HD cells by slow centrifugation in high-density albumin were labeled and transfused. Mean survival of a platelet cohort enriched with HD cells was significantly (P less than 0.02) shorter (7.73 days) than that of a cohort enriched with LD cells (9.33) days). In normal subjects treated with aspirin, capacity for thromboxane synthesis was regained more rapidly (P less than 0.05) in LD than in HD platelets. HD and LD platelets differed only slightly in mean volume (HD platelets . 7.57 mu3, LD platelets . 6.87 mu3, 0.05 less than P less than 0.01). We believe the most logical interpretation of these findings is that under normal conditions in man, newly formed platelets are less dense on the average than total platelets and become more dense as they age in the circulation. Thus, specific radioactivity of LD platelets declines rapidly as these platelets move into a more dense compartment and are replaced by newly formed, unlabelled cells; specific radioactivity of HD platelets remains constant or increases as labelled platelets enter this compartment in numbers equal to or greater than the number leaving it at the end of their life span. The similarity in mean volumes of LD and HD platelets suggests that platelet size is unrelated to platelet age under normal conditions.

  15. Effectiveness of Pooled Platelet Transfusion in Concordant and Discordant Groups among Dengue Patients

    PubMed Central

    Chowdappa, Vijaya; Masamatti, Smita Surendra

    2016-01-01

    Introduction Dengue affects more than 50 million people per year and is one of the most common causes of severe thrombocytopaenia. Thrombocytopaenia is a common complication of dengue and other viral fevers apart from malaria, typhoid, leptospirosis, leukaemia and megaloblastic anaemia. A platelet count of <20,000/μl is characteristically seen in dengue haemorrhagic fever and dengue fever. It results from immune complex mediated platelet destruction or bone marrow suppression. Severe thrombocytopaenia <10,000/μl is one of the indications for prophylactic platelet transfusion therapy to prevent haemorrhage. Aim To evaluate the effectiveness of transfusion of ABO compatible and ABO incompatible pooled platelet units in severe thrombocytopaenia cases. Materials and Methods In this study ABO compatible and incompatible pooled platelet units were transfused to serologically confirmed dengue cases having thrombocytopaenia with or without bleeding manifestations. Each of the adult patients received 4-6 units of pooled platelet concentrates prepared from random donor whole blood suspended in plasma for severe thrombocytopaenia. Pre and post transfusion platelet counts were compared. Children aged less than 12 years, pregnant women and patients with splenomegaly those on ayurvedic and homeopathic therapy, recipients of packed red cells on the same day of platelet transfusion and recipients of multiple platelet transfusions within 24 hours were excluded from the study. Results The median post transfusion platelet increments (PPI) and corrected count increments (CCI) at 4hour post transfusion were 25,000/μL (5,000-80,000/μL) and 18,000/μL (range 8,000/μL- 47,500/μL) respectively among the responders. Median PPI and CCI at 24 hours were 45,000/μL and 28,863/μL among the responders. The median CCI at 4 hour post transfusion among the non-responders was 850/μL and at 24hours was 1,425/μL. At 24 hours responders showed significantly higher PPI as compared to non

  16. Signaling during platelet adhesion and activation

    PubMed Central

    Li, Zhenyu; Delaney, M. Keegan; O’Brien, Kelly A.; Du, Xiaoping

    2011-01-01

    Upon vascular injury, platelets are activated by adhesion to adhesive proteins like von Willebrand factor and collagen, or by soluble platelet agonists like ADP, thrombin, and thromboxane A2. These adhesive proteins and soluble agonists induce signal transduction via their respective receptors. The various receptor-specific platelet activation signaling pathways converge into common signaling events, which stimulate platelet shape change, granule secretion, and ultimately induce the “inside-out” signaling process leading to activation of the ligand binding function of integrin αIIbβ3. Ligand binding to integrin αIIbβ3 mediates platelet adhesion and aggregation and triggers “outside-in” signaling, resulting in platelet spreading, additional granule secretion, stabilization of platelet adhesion and aggregation, and clot retraction. It has become increasingly evident that agonist-induced platelet activation signals also crosstalk with integrin “outside-in” signals to regulate platelet responses. Platelet activation involves a series of rapid positive feedback loops that greatly amplify initial activation signals, and enable robust platelet recruitment and thrombus stabilization. Recent studies have provided novel insight into the molecular mechanisms of these processes. PMID:21071698

  17. Platelet-rich plasma preparation for regenerative medicine: optimization and quantification of cytokines and growth factors

    PubMed Central

    2013-01-01

    Introduction Platelet-rich plasma (PRP) is nowadays widely applied in different clinical scenarios, such as orthopedics, ophthalmology and healing therapies, as a growth factor pool for improving tissue regeneration. Studies into its clinical efficiency are not conclusive and one of the main reasons for this is that different PRP preparations are used, eliciting different responses that cannot be compared. Platelet quantification and the growth factor content definition must be defined in order to understand molecular mechanisms behind PRP regenerative strength. Standardization of PRP preparations is thus urgently needed. Methods PRP was prepared by centrifugation varying the relative centrifugal force, temperature, and time. Having quantified platelet recovery and yield, the two-step procedure that rendered the highest output was chosen and further analyzed. Cytokine content was determined in different fractions obtained throughout the whole centrifugation procedure. Results Our method showed reproducibility when applied to different blood donors. We recovered 46.9 to 69.5% of total initial platelets and the procedure resulted in a 5.4-fold to 7.3-fold increase in platelet concentration (1.4 × 106 to 1.9 × 106 platelets/μl). Platelets were highly purified, because only <0.3% from the initial red blood cells and leukocytes was present in the final PRP preparation. We also quantified growth factors, cytokines and chemokines secreted by the concentrated platelets after activation with calcium and calcium/thrombin. High concentrations of platelet-derived growth factor, endothelial growth factor and transforming growth factor (TGF) were secreted, together with the anti-inflammatory and proinflammatory cytokines interleukin (IL)-4, IL-8, IL-13, IL-17, tumor necrosis factor (TNF)-α and interferon (IFN)-α. No cytokines were secreted before platelet activation. TGF-β3 and IFNγ were not detected in any studied fraction. Clots obtained after platelet coagulation

  18. Effect of stress hormones on the expression of fibrinogen-binding receptors in platelets.

    PubMed

    Lam, Nicole Y-L; Rainer, Timothy H; Ng, Margaret H-L; Leung, Yonna; Cocks, Robert A

    2002-12-01

    Acute coagulopathy is a common clinical complication after trauma, and contributes to posttraumatic multiple organ failure. The phenomenon may be due to the effect of stress hormones on platelet adhesion molecule expression after trauma. Catecholamine levels correlate with injury severity scores and changes of L-selectin expression on leucocytes, whilst adrenaline (ADR) (epinephrine) alone also activates platelets. This study thus investigates the effects of ADR and noradrenaline (NOR) (norepinephrine) on platelets, at doses similar to those found in the plasma of normal and trauma subjects. Blood was taken from 19 healthy subjects and placed in tubes containing sodium citrate. Anti-platelet-bound fibrinogen monoclonal antibody was used to identify the activated platelets while anti-CD41 was used to identify platelets with and without activation. Five increasing concentrations of ADR and NOR (1, 3, 5, 10, 30 nmol/l) as well as one negative control (0.9% normal saline) and one positive control (10 micromol/l adenosine diphosphate/ADP) were prepared for the stimulation. A whole blood protocol was used in order to minimize any activation artefacts, which might be created by centrifugation. The percentage of platelets expressing fibrinogen receptors increased significantly with ADR and NOR even at the lowest dose (1 nmol/l) and continued to increase in a dose-dependent manner. Although the effect of ADR was greater than NOR in stimulating platelets to express fibrinogen receptors, the average number of fibrinogen receptors on each platelet was constant. ADR and NOR activated platelets to express fibrinogen receptors at doses that are similar to those found in the plasma of trauma patients. PMID:12458065

  19. Platelet adhesion and activation on polyethylene glycol modified polyurethane surfaces. Measurement of cytoplasmic calcium.

    PubMed

    Park, K D; Suzuki, K; Lee, W K; Lee, J E; Kim, Y H; Sakurai, Y; Okano, T

    1996-01-01

    Polyurethane (PU) surfaces were modified by coupling polyethylene glycol (PEG; molecular weight, 1,000) chains carrying different terminal groups (PU-PEG1K-OH, PU-PEG1K-NH2, PU-PEG1K-SO3) and longer PEG chains (MW, 3,350; PU-PEG3.4K-OH). The modified PU surfaces have the same PEG (1K) chain density. Surface induced platelet activation was evaluated by measuring cytoplasmic free calcium concentration in platelets contacting modified surfaces, and platelet adhesion onto modified surfaces was investigated in vitro. Cytoplasmic free calcium levels in platelets contacting PU-PEG-SO3 remained relatively constant, in contrast to the significant increase observed for PU-PEG-NH2, PU-PEG-OH, and control PU surfaces. The degree of platelet adhesion clearly demonstrates that all PEG graft surfaces prevented platelet adhesion. Among PEG1K surfaces, PU-PEG-SO3 shows the lowest platelet adhesion. In the case of relatively longer PEG grafted surfaces (PU-PEG3.4K-OH and PU-PEG3.4K-Hep), both surfaces were found to prevent the increase in both cytoplasmic free calcium and platelet adhesion. These results suggest that longer PEG chain grafting is more effective than shorter grafting in preventing platelet activation and adhesion because of the highly dynamic movement of hydrated PEG chains at the interface. In addition, in vitro platelet interaction is dependent upon terminal groups of PEG chains on PEG1K series surfaces. PMID:8945010

  20. Glaucocalyxin A inhibits platelet activation and thrombus formation preferentially via GPVI signaling pathway.

    PubMed

    Li, Wei; Tang, Xiaorong; Yi, Wenxiu; Li, Qiang; Ren, Lijie; Liu, Xiaohui; Chu, Chunjun; Ozaki, Yukio; Zhang, Jian; Zhu, Li

    2013-01-01

    Platelets play a pivotal role in atherothrombosis and the antiplatelet agents have been proved to be useful in preventing onset of acute clinical events including myocardial infarction and stroke. Increasing number of natural compounds has been identified to be potential antiplatelet agents. Here we report the antiplatelet effect of glaucocalyxin A (GLA), an ent-diterpenoid that we isolated and purified from the aerial parts of Rabdosia japonica (Burm. f.) var. glaucocalyx (Maxim.) Hara, and investigate the molecular mechanisms by which GLA inhibits platelet activation and thrombus formation. The effect of GLA on platelet activation was measured using platelets freshly isolated from peripheral blood of healthy donors. Results showed that pretreatment of human platelets with lower concentrations of GLA (0.01 μg/ml, 0.1 μg/ml) significantly inhibited platelet aggregation induced by collagen (P<0.001) and CRP (P<0.01), a synthetic GPVI ligand, but not by ADP and U46619. Accordingly, GLA inhibited collagen-stimulated tyrosine phosphorylation of Syk, LAT, and phospholipase Cγ2, the signaling events in collagen receptor GPⅥ pathway. GLA also inhibited platelet p-selectin secretion and integrin activation by convulxin, a GPVI selective ligand. Additionally, GLA was found to inhibit low-dose thrombin-induced platelet activation. Using a flow chamber device, GLA was found to attenuate platelet adhesion on collagen surfaces in high shear condition. In vivo studies showed that GLA administration increased the time for complete occlusion upon vascular injury in mice, but did not extend tail-bleeding time when mice were administered with relatively lower doses of GLA. Therefore, the present results provide the molecular basis for the inhibition effect of GLA on platelet activation and its in vivo effect on thrombus formation, suggesting that GLA could potentially be developed as an antiplatelet and antithrombotic agent. PMID:24386454

  1. The nature of interactions between tissue-type plasminogen activator and platelets

    SciTech Connect

    Torr, S.R.; Winters, K.J.; Santoro, S.A.; Sobel, B.E. )

    1990-07-15

    To elucidate interactions responsible for inhibition of aggregation of platelets in platelet-rich plasma (PRP) harvested from whole blood preincubated with t-PA, experiments were performed with PRP and washed platelets under diverse conditions of preincubation. Both ADP and collagen induced aggregation were inhibited in PRP unless aprotinin had been added to the preincubated whole blood concomitantly with t-PA. However, in washed platelets prepared after the same exposure aggregation was intact. When washed platelets were supplemented with fibrinogen degradation products (FDPs) in concentrations simulating those in whole blood preincubated with t-PA, aggregation induced with either ADP or collagen was inhibited. Thus, the inhibition in PRP depended on generation of FDPs by activated plasminogen. The functional integrity of surface glycoprotein (GP) IIb/IIIa receptors in washed platelets was documented by autoradiography after SDS-PAGE of surface labeled GPs and by fibrinogen binding despite preincubation of the whole blood or washed platelets themselves with t-PA and plasminogen as long as exogenous calcium (greater than or equal to 0.1 microM) was present. In contrast, when calcium was absent, the platelet GP IIb/IIIa receptor was rendered susceptible to degradation by plasmin, and aggregation was inhibited by preincubation at 37 degrees C even if aprotinin was present when aggregation was being assayed. These observations reconcile disparate results in the literature from studies in vivo and in vitro by demonstrating that inhibition of aggregation of platelets in PRP and in whole blood reflects indirect effects of plasminogen activation rather than direct effects of t-PA or plasmin on the platelets themselves.

  2. Manipulating megakaryocytes to manufacture platelets ex vivo

    PubMed Central

    Karagiannis, P; Eto, K

    2015-01-01

    Historically, platelet transfusion has proven a reliable way to treat patients suffering from thrombocytopenia or similar ailments. An undersupply of donors, however, has demanded alternative platelet sources. Scientists have therefore sought to recapitulate the biological events that convert hematopoietic stem cells into platelets in the laboratory. Such platelets have shown good function and potential for treatment. Yet the number manufactured ex vivo falls well short of clinical application. Part of the reason is the remarkable gaps in our understanding of the molecular mechanisms driving platelet formation. Using several stem cell sources, scientists have progressively clarified the chemical signaling and physical microenvironment that optimize ex vivo platelets and reconstituted them in synthetic environments. Key advances in cell reprogramming and the ability to propagate self-renewal have extended the lifetime of megakaryocytes to increase the pool of platelet progenitors. PMID:26149050

  3. Role of platelets in allergic airway inflammation.

    PubMed

    Idzko, Marco; Pitchford, Simon; Page, Clive

    2015-06-01

    Increasing evidence suggests an important role for platelets and their products (e.g., platelet factor 4, β-thromboglobulin, RANTES, thromboxane, or serotonin) in the pathogenesis of allergic diseases. A variety of changes in platelet function have been observed in patients with asthma, such as alterations in platelet secretion, expression of surface molecules, aggregation, and adhesion. Moreover, platelets have been found to actively contribute to most of the characteristic features of asthma, including bronchial hyperresponsiveness, bronchoconstriction, airway inflammation, and airway remodeling. This review brings together the current available data from both experimental and clinical studies that have investigated the role of platelets in allergic airway inflammation and asthma. It is anticipated that a better understanding of the role of platelets in the pathogenesis of asthma might lead to novel promising therapeutic approaches in the treatment of allergic airway diseases. PMID:26051948

  4. [The equation for platelet aggregation rate].

    PubMed

    Vrzheshch, P V; Verkhusha, V V; Varfolomeev, S D

    1990-01-01

    A platelet aggregation model in shear flow taking into account the kinetics of intercellular fibrinogen bond formation limited by aggregated platelets rotation time was considered. For this consideration the average duration of platelets interaction in flow with shear rate value G is shown to be pi/4G. One fibrinogen bond is sufficient to form a solid aggregate between two platelets. The equation for single platelets disappearance rate concerned with intercellular fibrinogen bond formation, stochastic character of bond distribution in collided platelets and hydrodynamically controlled interaction time was obtained. The Hill's approximation for the obtained aggregation rate dependences was suggested and appropriate constants were determined. The qualitative criterion of platelets aggregating systems behavior was introduced. PMID:2245229

  5. Platelet-Rich Plasma in a Patient with Cerebral Palsy

    PubMed Central

    Alcaraz, Jesús; Oliver, Antonio; Sánchez, Juana María

    2015-01-01

    Patient: Male, 6 Final Diagnosis: Cerebral palsy secundary perinatal hypoxia Symptoms: Cognitive impairment • epilectic seizure Medication: Platelet rich plasma Clinical Procedure: Cognitive improvement with neuroestimulator and neuroregenerator power of platelet rich plasma injection Specialty: Hematology Objective: Unusual clinical course Background: The use of platelet-rich plasma is a now a common medical technique known as regenerative medicine, through power cell activation and differentiation, which produces growth factors called platelets derived both locally and systematically. Here, we report the case of a cerebral palsy patient who received intravenous platelet-rich plasma. Case Report: We administered an intravenous injection of concentrated platelet-rich plasma (25 cc) in a 6-year-old boy with perinatal cerebral palsy, cognitive impairment, and marked and severe generalized spasticity. We performed follow-up at 3 and 6 months after the injection. All serum samples for determination were obtained by ELISA technique. Cognitive scales (Bayley, Battelle, M.S.C.A, Kaufman ABC, and Stanford-Binet Intelligence scale) were used before and after treatment. The determination protocol that was applied before the analysis was performed manually and the autotransfusion was considered suitable for treatment. We determined the plasma levels of factor similar to insulin-1 (IGF-1), platelet-derived growth factor (PDGF), vasculo-endothelial growth factor (VEGF), and transforming growth factor B (TGF-B) before and during treatment monitoring. Conclusions: No adverse effects were observed in the patient except for a small hematoma in the area channeling venous access. We observed a clear improvement in the cognitive sphere (memory, ability to perform more complex tasks, and acquisition of new skills) and in language, maintaining stable levels of growth factor in plasma 3–5 times higher than average for his age group at both 3- and 6-month follow-up. Positron emission

  6. beta-Dystroglycan modulates the interplay between actin and microtubules in human-adhered platelets.

    PubMed

    Cerecedo, Doris; Cisneros, Bulmaro; Suárez-Sánchez, Rocío; Hernández-González, Enrique; Galván, Iván

    2008-05-01

    To maintain the continuity of an injured blood vessel, platelets change shape, secrete granule contents, adhere, aggregate, and retract in a haemostatic plug. Ordered arrays of microtubules, microfilaments, and associated proteins are responsible for these platelet responses. In full-spread platelets, microfilament bundles in association with other cytoskeleton proteins are anchored in focal contacts. Recent studies in migrating cells suggest that co-ordination and direct physical interaction of microtubules and actin network modulate adhesion development. In platelets, we have proposed a feasible association between these two cytoskeletal systems, as well as the participation of the dystrophin-associated protein complex, as part of the focal adhesion complex. The present study analysed the participation of microtubules and actin during the platelet adhesion process. Confocal microscopy, fluorescence resonance transfer energy and immunoprecipitation assays were used to provide evidence of a cross-talk between these two cytoskeletal systems. Interestingly, beta-dystroglycan was found to act as an interplay protein between actin and microtubules and an additional communication between these two cytoskeleton networks was maintained through proteins of focal adhesion complex. Altogether our data are indicative of a dynamic co-participation of actin filaments and microtubules in modulating focal contacts to achieve platelet function. PMID:18341635

  7. Mean platelet volume as an indicator of platelet rejuvenation following bone-marrow transplantation. Master's thesis

    SciTech Connect

    Seanger, D.G.

    1986-07-01

    Thrombocytopenia of unpredictable duration and severity is an expected outcome of the radiation/chemotherapy protocols performed prior to bone-marrow transplantation. Serial evaluation of the platelet count and mean platelet volume of patients diagnosed with acute leukemia demonstrated the mean platelet volume to increase into reference limits 24 to 40 hours prior to a rise in the platelet count in those patients whose bone-marrow successfully responded to induction chemotherapy. Serial platelet counts and measurements of mean platelet volume were performed on 31 patients following bone marrow transplantation. Numerous platelet transfusions, together with sustained thrombocytopenia, inhibited accurate assessment of 29 of 31 patients. Two patients, however, demonstrated a rise in the mean platelet volume prior to an increase in the platelet count. Both of these patients received no platelet transfusions during the period preceding or following the rise in the platelet count. It was proposed that the serial evaluation of the mean platelet volume may assist practitioners in the decision-making process of deciding whether platlet transfusions are required, or an increase in the number of circulating platelets is imminent. A decision not to transfuse would have the direct benefit of decreasing patient costs, in conjunction with eliminating a potential source for the development of an antibody against platelets.

  8. 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

  9. Membrane Changes Associated with Platelet Activation

    PubMed Central

    George, James N.; Lyons, Roger M.; Morgan, Rebecca K.

    1980-01-01

    The effect of aggregation and secretion on membrane proteins was studied in washed human platelets. Reversible aggregation without secretion was stimulated by ADP and secretion without aggregation was stimulated by thrombin in the presence of EDTA. No loss of platelet surface glycoproteins occurred during reversible ADP-induced platelet aggregation, as measured by quantitative polyacrylamide gel electrophoresis analysis of platelets that were labeled with 125I-diazotized diiodosulfanilic acid (DD125ISA) before ADP stimulation. Also, no new proteins became exposed on the platelet surface after ADP aggregation, as determined by DD125ISA labeling after stimulation. Thrombin-induced platelet secretion also caused no loss of platelet surface glycoproteins. However, after platelet secretion two new proteins were labeled by DD125ISA: (a) actin and (b) the 149,000-mol wt glycoprotein (termed GP-G), which is contained in platelet granules and secreted in response to thrombin. The identity of DD125ISA-labeled actin was confirmed by four criteria: (a) comigration with actin in three different sodium dodecyl sulfate-polyacrylamide gel electrophoresis systems, (b) elution from a particulate fraction in low ionic strength buffer, (c) co-migration with actin in isoelectric focusing, and (d) binding to DNase I. The identity of actin and its appearance on the platelet surface after thrombin-induced secretion was also demonstrated by the greater binding of an anti-actin antibody to thrombin-treated platelets, measured with 125I-staphylococcal protein A. Therefore, major platelet membrane changes occur after secretion but not after reversible aggregation. The platelet surface changes occurring with secretion may be important in the formation of irreversible platelet aggregates and in the final retraction of the blood clot. Images PMID:6772667

  10. Early increase in DcR2 expression and late activation of caspases in the platelet storage lesion.

    PubMed

    Plenchette, S; Moutet, M; Benguella, M; N'Gondara, J P; Guigner, F; Coffe, C; Corcos, L; Bettaieb, A; Solary, E

    2001-10-01

    Platelet transfusion is widely used to prevent bleeding in patients with severe thrombocytopenia. The maximal storage duration of platelet concentrates is usually 5 days, due to the platelet storage lesion that impairs their functions when stored for longer times. Some of the morphological and biochemical changes that characterize this storage lesion are reminiscent of cell death by apoptosis. The present study analyzed whether proteins involved in nucleated cell apoptosis could play a role in the platelet storage lesion. Storage of leukocyte-depleted platelets obtained by apheresis is associated with a late and limited activation of caspases, mainly caspase-3. This event correlates with an increased expression of the pro-apoptotic BH3-only protein Bim in the particulate fraction and a slight and late release of the pro-apoptotic mitochondrial protein Diablo/Smac in the cytosol. Platelets do not express the death receptors Fas, DR4 and DR5 on their plasma membrane, while the expression of the decoy receptor DcR2 increases progressively during platelet storage. Addition of low concentrations of the cryoprotector dimethylsulfoxide accelerates platelet caspase activation during storage, an effect that is partially prevented by the caspase inhibitor z-VAD-fmk. Altogether, DcR2 expression on the plasma membrane is an early event while caspase activation is a late event during platelet storage. These observations suggest that caspases are unlikely to account for the platelet storage lesion. As a consequence, addition of caspase inhibitors may not improve the quality of platelet concentrates stored in standard conditions. PMID:11587215

  11. Flavonoids inhibit the platelet TxA2 signalling pathway and antagonize TxA2 receptors (TP) in platelets and smooth muscle cells

    PubMed Central

    Guerrero, José A; Navarro-Nuñez, Leyre; Lozano, María L; Martínez, Constantino; Vicente, Vicente; Gibbins, Jonathan M; Rivera, José

    2007-01-01

    mobilization in a concentration-dependent manner (IC50 10–30 µm). These flavonoids caused a significant impairment of U46619-induced platelet tyrosine phosphorylation and of ERK 1/2 activation. By contrast, in aspirin-treated platelets all these flavonoids, except quercetin, displayed minor effects on thrombin-induced calcium mobilization, ERK 1/2 and total tyrosine phosphorylation. Finally, apigenin, genistein and luteolin inhibited by >50% 3H-SQ29548 binding to different cell types. Conclusions These data further suggest that flavonoids may inhibit platelet function by binding to TP and by subsequent abrogation of downstream signalling. Binding of these compounds to TP occurs in human myometrium and in TP-transfected HEK 293T cells and suggests that antagonism of TP might mediate the effects of flavonoids in different tissues. PMID:17425630

  12. Lysosomotropic agents selectively potentiate thrombin-induced acid hydrolase secretion from platelets.

    PubMed Central

    Van Oost, B A; Smith, J B; Holmsen, H; Vladutiu, G D

    1985-01-01

    Thrombin induces partial secretion (up to 60%) of beta-N-acetyl-D-hexosaminidase (EC 3.2.1.52) from untreated platelets. Preincubation of platelets with 10 mM NH4Cl for up to 2 hr resulted in a time-dependent and marked stimulation of thrombin-induced secretion of both this enzyme and other acid glycosidases from platelets. The enhancement of the thrombin-induced secretion was not due to cell lysis, and NH4Cl alone did not cause leakage of lysosomal enzymes into the medium. The effect could be reversed by reincubating the platelets in NH4Cl-free medium. Stimulation of thrombin-induced secretion also was produced by a series of aliphatic primary amines from methylamine to butylamine, and by micromolar concentrations of chloroquine. The effect of weak bases on platelets appeared to be quite specific for enhancing lysosomal enzyme secretion. Thrombin-induced secretion of adenine nucleotides from dense granules and of beta-thromboglobulin from alpha granules was slightly enhanced by NH4Cl but was slightly inhibited by methylamine. The only direct effect of the weak bases on platelets was the displacement of serotonin from dense granules. Accumulation of weak bases in acidic pools in the platelets (e.g., lysosomes) might, therefore, be responsible for the enhanced secretion of lysosomal enzymes. By using controlled digitonin-induced platelet lysis, it was found that preincubation of platelets with NH4Cl lowered the digitonin concentration required for enzyme solubilization. We suggest that loading of lysosomes with weak bases dissociates already bound enzyme inside the lysosomes, resulting in a more effective discharge upon stimulation by thrombin. PMID:3157989

  13. Comparative evaluation of antiplatelet effect of lycopene with aspirin and the effect of their combination on platelet aggregation: An in vitro study

    PubMed Central

    Sawardekar, Swapna B.; Patel, Tejal C.; Uchil, Dinesh

    2016-01-01

    Introduction: The objective was to compare antiplatelet effect of lycopene with aspirin and to study effect of combination of the two on platelet aggregation in vitro, using platelets from healthy volunteers. Materials and Methods: Platelets were harvested; platelet count of platelet-rich plasma adjusted to 2.5 Χ 105/μL. Aspirin (140 μmol/L) and lycopene (4, 6, 8, 10, and 12 μmol/L) were studied in vitro against adenosine-5’- diphosphate (ADP) (2.5 μM/L) and collagen Results: All the concentrations of lycopene (4–12 μmol/L) exhibited reduction in maximum platelet aggregation induced by aggregating agents ADP and collagen (P < 0.01 vs. vehicle) and were comparable with aspirin. Lycopene at concentration 10 μmol/L showed maximum platelet inhibition (47.05% ± 19.56%) against ADP, whereas lycopene at concentration 8 μmol/L showed maximum platelet inhibition (54.26% ± 30.71%) against collagen. Four μmol/L of lycopene combined with 140 μmol/L and 70 μmol/L aspirin showed greater inhibition of platelets as compared to aspirin 140 μmol/L alone, against both ADP and collagen. Conclusion: The study favorably compares lycopene and aspirin with respect to their antiplatelet activities against ADP and collagen. Lycopene can be considered as a potential target for modifying the thrombotic and pro-inflammatory events associated with platelet activation. PMID:26997718

  14. Assessment of platelet activation in several different anticoagulants by the Advia 120 Hematology System, fluorescence flow cytometry, and electron microscopy.

    PubMed

    Ahnadi, Charaf E; Sabrinah Chapman, E; Lépine, Mariette; Okrongly, David; Pujol-Moix, Nuria; Hernández, Angel; Boughrassa, Faiza; Grant, Andrew M

    2003-11-01

    In vivo platelet activation results are often confounded by activation induced in vitro during the preparative procedures. We measured ex vivo (basal) and in vitro (thrombin-induced) platelet activation in sodium citrate, ethylenediaminetetraacetic acid (EDTA), and Citrate Theophylline Dipyridamole Adenosine (CTAD) whole blood specimens. Determinations were made by measurements of platelet density (mean platelet component: MPC concentration) on the Advia 120 Hematology System. The MPC has been previously shown to correlate with a fluorescence flow cytometric method, also determined in this study, using the surface expression of CD62P. Moreover, platelet shape and structure changes in EDTA and CTAD anticoagulated whole blood specimens were characterized by transmission electron microscopy (TEM). Observations made using the Advia 120 Hematology System platelet density parameter, MPC, in the absence of thrombin were 25.7 +/- 0.9 g/dl, 27.9 +/- 0.9 g/dl and 24.8 +/- 1.2 g/dl in sodium citrate, EDTA and CTAD whole blood specimens, respectively. Addition of thrombin induced a significant change in platelet MPC for sodium citrate (21.9 +/- 1.9 g/dl; p<0.0001) and EDTA (23.2 +/- 0.9 g/dl; p<0.0001) whole blood specimens. In contrast, thrombin had no effect on MPC measured in whole blood taken into CTAD tubes. In vitro fluorescence flow cytometric platelet activation experiments measuring the percentage of platelets expressing anti-CD62P showed increase in sodium citrate specimens from 9.2 +/- 7.0 to 55.5 +/- 23.1 % (p<0.0001) and in EDTA specimens from 1.9 +/- 1.7 to 64.6 +/- 12.4 % (p<0.0001) after addition of thrombin. However, in blood taken into CTAD tubes, there was no significant change. Studies on platelets isolated from whole blood in CTAD showed activation by thrombin indicating that platelets in CTAD, while protected in its presence remained functional upon its removal. When observed by TEM over time, platelets in EDTA appear more activated and contain fewer

  15. Platelet collagen receptors and coagulation. A characteristic platelet response as possible target for antithrombotic treatment.

    PubMed

    Heemskerk, Johan W M; Kuijpers, Marijke J E; Munnix, Imke C A; Siljander, Pia R M

    2005-04-01

    Collagen is a unique agonist of platelets, because it acts as an immobilized ligand that only causes platelet activation after stable adhesion. This review addresses the present understanding of how platelet interaction with collagen supports the process of thrombin generation and coagulation. Only some of the collagen-adhered platelets, that is, those showing profound changes in shape and shedding microparticles (resembling apoptotic cells), appear to contribute to the procoagulant activity of platelets. The main signaling receptor for collagen, glycoprotein VI, plays a key role in the platelet procoagulant response during thrombus formation; this is a reason why new anti-glycoprotein-VI antibodies are promising antithrombotic tools. PMID:16039967

  16. Partitioning of Laponite Clay Platelets in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-01-12

    Partitioning of laponite disklike clay platelets between polymer particles and bulk aqueous phase was investigated in Pickering surfactant-free emulsion polymerization of styrene. Adsorption of laponite clay platelets plays an important role in the stabilization of this system, influencing the particle size and the number of particles, and, hence, the reaction rate. Adsorption isotherms show that, while the laponite clay platelets are almost fully exfoliated in water, they form multilayers on the surface of the polymer particles by the end of polymerization, as confirmed by transmission electron microscopy (TEM). This observation is supported by quartz crystal microbalance, conductivity, and TEM measurements, which reveal interactions between the clay and polystyrene, as a function of the ionic strength. The strong adsorption of clay platelets leaves a low residual concentration in the aqueous phase that cannot cause further nucleation of polymer particles, as demonstrated during seeded emulsion polymerization experiments in the presence of a high excess of clay. A Brunauer-Emmett-Teller (BET)-type model for laponite adsorption on polystyrene particles matches the adsorption isotherms. PMID:26653971

  17. Antithrombotic activity of Vitis labrusca extract on rat platelet aggregation.

    PubMed

    Kwon, Se-Uk; Lee, Hoon-Yeon; Xin, Mingjie; Ji, Su-Jeong; Cho, Hyoung-Kwon; Kim, Dae-Sung; Kim, Dae-Ki; Lee, Young-Mi

    2016-03-01

    Vitis labrusca is a grapevine that has antioxidant, neuroprotective, hepatoprotective, and anticarcinogenic activity. However, the antithrombotic effect of Vitis labrusca leaves on platelets is yet to be ascertained. We investigated the inhibitory effect of V. labrusca leaf extract (VLE) on platelet aggregation in vitro and ex vivo. The thromboxane B2 (TXB2) and serotonin concentrations were measured by ELISA. The flavonoids content was measured by ultraperformance liquid chromatography (UPLC). The antithrombotic activity of VLE was evaluated using various agonists in vitro. VLE strongly inhibited adenosine diphosphate (ADP)-induced platelet aggregation. In rats, VLE treatment (100 mg/kg) reduced ADP-stimulated platelet aggregation, without affecting tail bleeding and coagulation time. Moreover, VLE significantly suppressed TXB2 and serotonin secretion. UPLC analysis indicated that VLE contains quercetin, isorhamnetin, and rutin. Our results indicate that VLE possesses antiplatelet activity via the suppression of TXB2 and serotonin, without affecting bleeding. Further, we identified the flavonoids present in VLE. Thus, VLE may be a potential agent for the prevention of cardiovascular diseases. PMID:26340455

  18. The effects of osmotic stress on human platelets.

    PubMed

    Armitage, W J; Parmar, N; Hunt, C J

    1985-05-01

    The effect of osmotic stress on human platelets was investigated at 0, 25, and 37 degrees C. The osmolality of the suspending plasma was decreased by adding water or increased by adding sodium chloride or sucrose. After 5 min, isotonicity was restored by dilution with an excess of isotonic phosphate-buffered saline. After centrifugation, the platelets were resuspended in autologous plasma and then incubated for 1 hr at 37 degrees C before assaying the active transport of 5-hydroxytryptamine (5-HT) and the hypotonic stress response. Anisosmotic conditions had a greater effect on the extent of volume reversal in the hypotonic stress test than on 5-HT uptake. At 25 degrees C, only moderate degrees of hypotonicity (0.25 osmol/kg) or hypertonicity (0.59 osmol/kg) were sufficient to depress the hypotonic stress response. In general, platelets tolerated departures from isotonic conditions better at 0 degree C than at the higher temperatures. Furthermore, at 0 and 25 degrees C approximately equiosmolal concentrations of sucrose and sodium chloride depressed the hypotonic stress response to similar extents, but at 37 degrees C high osmolalities (greater than 2 osmol/kg) were tolerated better when the additive was sucrose than when it was sodium chloride. Platelets shrank when subjected to hyperosmotic conditions, but their discoid shape and the peripheral band of microtubules were maintained. PMID:3980588

  19. Structure-guided creation of AcAP5-derived and platelet targeted factor Xa inhibitors.

    PubMed

    Zhu, Yuanjun; Lin, Yuan; Liu, Aihua; Shui, Mengyang; Li, Ruyi; Liu, Xiaoyan; Hu, Wenhui; Wang, Yinye

    2015-06-15

    Anticoagulants and anti-platelet agents are simultaneously administrated in clinical practice (i.e. percutaneous coronary intervention), which cause significant risk of systemic bleeding. Targeted delivery of anticoagulants to the activated platelets at sites of vascular injuries may condense the site-specific anticoagulant effect and reduce the hemorrhage side effects in uninjured vessels. To this end, we prepared three ancylostoma caninum anticoagulant peptide 5 (AcAP5) variants NR1, NR2 and NR3 engineered with a platelet-binding Arg-Gly-Asp (RGD) motif and evaluated their anti-Factor Xa (FXa) and platelet-binding effects. These RGD-containing AcAP5 variants were capable of interacting with platelet receptor αIIbβ3 as shown in computational analysis. All variants, especially NR2 and NR3, retained entirely the anti-FXa function of parent AcAP5. Moreover, they prevented the formation of occlusive thrombi in rat carotid artery injury model, suggesting that they inhibit platelet aggregation in vivo. Further functional investigation of NR3 demonstrated that NR3 inhibited platelet aggregation in vitro and FXa activity in vivo, and prolonged the coagulation time, all in a dose-dependent manner. Through flow cytometry assay, we confirmed the binding of NR3 to αIIbβ3 receptor. In mouse model of carotid artery endothelium injury, NR3-treated mice showed less tail bleeding time than AcAP5-treated mice, and aspirin plus NR3 treatment exhibited moderate reduction of blood loss compared with aspirin plus AcAP5 treatment. These results indicate the feasibility to engineer a novel FXa inhibitor specifically targeting the activated platelets, which centralizes its anticoagulation efficacy in the injured vascular endothelium and reduces the risk of systemic bleeding. PMID:25887920

  20. A numerical model for the platelet heat-pipe-cooled leading edge of hypersonic vehicle

    NASA Astrophysics Data System (ADS)

    Liu, Hongpeng; Liu, Weiqiang

    2016-01-01

    A new design, the platelet heat-pipe-cooled leading edge, is discussed for the thermal management to prevent damage to hypersonic vehicle leading edge component. For calculating the steady state behavior of platelet heat-pipe-cooled leading edge, a numerical model based on the principles of evaporation, convection, and condensation of a working fluid is presented. And then its effectiveness is validated by comparing the wall and vapor temperature against experimental data for a conventional heat pipe. Further investigations indicate that alloy IN718, with sodium as the working fluid is a feasible combination for Mach 8 flight with a 15 mm leading edge radius.

  1. Quantitation of platelet and fibrinogen-fibrin deposition on components of tissue valves (Ionescu-Shiley) in calves

    SciTech Connect

    Dewanjee, M.K.; Solis, E.; Lenker, J.; Tidwell, C.; Mackey, S.; Didisheim, P.; Kaye, M.P.

    1986-07-01

    With /sup 111/In-labeled platelets and /sup 125/I-labeled bovine fibrinogen, regional mapping of platelet and fibrinogen deposition on leaflets and sewing rings was obtained. Ten Holstein calves received 25-mm mitral valves (ISLM) and were killed 1, 14, and 30 days after implantation. Twenty-four hours before the calves were killed, 350 to 450 microCi of /sup 111/In-labeled platelets and 200 to 250 microCi of /sup 125/I-labeled bovine fibrinogen were administered intravenously. The components of the tissue valves, i.e., three leaflets and sewing rings, were separated. Each leaflet was cut into four sections: free edge, central zone, flexion zone, and attachment zone. From the radioactivity in blood, leaflet zones, sewing rings, area of leaflet zones, platelet count, and fibrinogen level in blood, the mean regional density of adherent platelets, fibrinogen-fibrin, and fibrinogen/platelet were calculated. The density of platelets and fibrinogen deposited on the components of the valves decreases with time postimplantation. The number of fibrinogen molecules per platelet is fivefold to 20-fold higher than that of the receptor concentration on platelets on leaflet zones, suggesting the heterogeneity of fibrinogen-fibrin in thrombus and components of the valve.

  2. The use of quartz crystal microbalance with dissipation (QCM-D) for studying nanoparticle-induced platelet aggregation

    PubMed Central

    Santos-Martinez, Maria Jose; Inkielewicz-Stepniak, Iwona; Medina, Carlos; Rahme, Kamil; D’Arcy, Deirdre M; Fox, Daniel; Holmes, Justin D; Zhang, Hongzhou; Radomski, Marek Witold

    2012-01-01

    Interactions between blood platelets and nanoparticles have both pharmacological and toxicological significance and may lead to platelet activation and aggregation. Platelet aggregation is usually studied using light aggregometer that neither mimics the conditions found in human microvasculature nor detects microaggregates. A new method for the measurement of platelet microaggregation under flow conditions using a commercially available quartz crystal microbalance with dissipation (QCM-D) has recently been developed. The aim of the current study was to investigate if QCM-D could be used for the measurement of nanoparticle-platelet interactions. Silica, polystyrene, and gold nanoparticles were tested. The interactions were also studied using light aggregometry and flow cytometry, which measured surface abundance of platelet receptors. Platelet activation was imaged using phase contrast and scanning helium ion microscopy. QCM-D was able to measure nanoparticle-induced platelet microaggregation for all nanoparticles tested at concentrations that were undetectable by light aggregometry and flow cytometry. Microaggregates were measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast and scanning helium ion microscopy. PMID:22275839

  3. Moderate oral supplementation with docosahexaenoic acid improves platelet function and oxidative stress in type 2 diabetic patients.

    PubMed

    Véricel, E; Colas, R; Calzada, C; Lê, Q H; Feugier, N; Cugnet, C; Vidal, H; Laville, M; Moulin, P; Lagarde, M

    2015-08-01

    Platelets from patients with type 2 diabetes are characterised by hyperactivation and high level of oxidative stress. Docosahexaenoic acid (DHA) may have beneficial effects on platelet reactivity and redox status. We investigated whether moderate DHA supplementation, given as a triglyceride form, may correct platelet dysfunction and redox imbalance in patients with type 2 diabetes. We conducted a randomised, double-blind, placebo-controlled, two-period crossover trial (n=11 post-menopausal women with type 2 diabetes) to test the effects of 400 mg/day of DHA intake for two weeks on platelet aggregation, markers of arachidonic acid metabolism, lipid peroxidation status, and lipid composition. Each two week-period was separated from the other by a six-week washout. Daily moderate dose DHA supplementation resulted in reduced platelet aggregation induced by collagen (-46.5 %, p< 0.001), and decreased platelet thromboxane B2 (-35 %, p< 0.001), urinary 11-dehydro-thromboxane B2 (-13.2 %, p< 0.001) and F2-isoprostane levels (-19.6 %, p< 0.001) associated with a significant increase of plasma and platelet vitamin E concentrations (+20 % and +11.8 %, respectively, p< 0.001). The proportions of DHA increased both in plasma lipids and in platelet phospholipids. After placebo treatment, there was no effect on any parameters tested. Our findings support a significant beneficial effect of low intake of DHA on platelet function and a favourable role in reducing oxidative stress associated with diabetes. PMID:25832443

  4. Detection of microbial contamination in platelets

    NASA Astrophysics Data System (ADS)

    Berg, Tracy L.; Leparc, German; Huffman, Debra E.; Gennaccaro, Angela L.; Garcia-Lopez, Alicia; Klungness, Greta; Stephans, Christie; Garcia-Rubio, Luis H.

    2005-03-01

    In the United States, approximately 100 patients develop fatal sepsis associated with platelet transfusions every year. Current culture methods take 24-48 hours to acquire results, which in turn decrease the shelf life of platelets. Many of the microorganisms that contaminate platelets can replicate easily at room temperature, which is the necessary storage temperature to keep platelets functional. Therefore, there is a need for in-situ quality control assessment of the platelet quality. For this purpose, a real time spectrophotometric technique has been developed. The Spectral Acquisition Processing Detection (SAPD) method, comprised of a UV-vis spectrophotometer and modeling algorithms, is a rapid method that can be performed prior to platelet transfusion to decrease the risk of bacterial infection to patients. The SAPD method has been used to determine changes in cell suspensions, based on size, shape, chemical composition and internal structure. Changes in these cell characteristics can in turn be used to determine microbial contamination, platelet aging and other physiologic changes. Detection limits of this method for platelet suspensions seeded with bacterial contaminants were identified to be less than 100 cfu/ml of sample. Bacterial counts below 1000 cfu/ml are not considered clinically significant. The SAPD method can provide real-time identification of bacterial contamination of platelets affording patients an increased level of safety without causing undue strain on laboratory budgets or personnel while increasing the time frame that platelets can be used by dramatically shortening contaminant detection time.

  5. 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

  6. Influence of Oxidative Stress on Stored Platelets

    PubMed Central

    2016-01-01

    Platelet storage and its availability for transfusion are limited to 5-6 days. Oxidative stress (OS) is one of the causes for reduced efficacy and shelf-life of platelets. The studies on platelet storage have focused on improving the storage conditions by altering platelet storage solutions, temperature, and materials. Nevertheless, the role of OS on platelet survival during storage is still unclear. Hence, this study was conducted to investigate the influence of storage on platelets. Platelets were stored for 12 days at 22°C. OS markers such as aggregation, superoxides, reactive oxygen species, glucose, pH, lipid peroxidation, protein oxidation, and antioxidant enzymes were assessed. OS increased during storage as indicated by increments in aggregation, superoxides, pH, conjugate dienes, and superoxide dismutase and decrements in glucose and catalase. Thus, platelets could endure OS till 6 days during storage, due to the antioxidant defense system. An evident increase in OS was observed from day 8 of storage, which can diminish the platelet efficacy. The present study provides an insight into the gradual changes occurring during platelet storage. This lays the foundation towards new possibilities of employing various antioxidants as additives in storage solutions. PMID:26949396

  7. Thromboxane-insensitive dog platelets have impaired activation of phospholipase C due to receptor-linked G protein dysfunction.

    PubMed Central

    Johnson, G J; Leis, L A; Dunlop, P C

    1993-01-01

    Human platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors are linked to phosphoinositide-specific phospholipase C (PI-PLC) via a G protein tentatively identified as a member of the Gq class. In contrast, platelet thrombin receptors appear to activate PI-PLC via other unidentified G proteins. Platelets from most dogs are TXA2 insensitive (TXA2-); i.e., they do not aggregate irreversibly or secrete although they bind TXA2, but they respond normally to thrombin. In contrast, a minority of dogs have TXA2-sensitive (TXA2+) platelets that are responsive to TXA2. To determine the mechanism responsible for TXA2- platelets, we evaluated receptor activation of PI-PLC. Equilibrium binding of TXA2/PGH2 receptor agonists, [125I]BOP and [3H]U46619, and antagonist, [3H]SQ29,548, revealed comparable high-affinity binding to TXA2-, TXA2+, and human platelets. U46619-induced PI-PLC activation was impaired in TXA2- platelets as evidenced by reduced (a) phosphorylation of the 47-kD substrate of protein kinase C, (b) phosphatidic acid (PA) formation, (c) rise in cytosolic calcium concentration, and (d) inositol 1,4,5 trisphosphate (IP3) formation, while thrombin-induced PI-PLC activation was not impaired. GTPase activity stimulated by U46619, but not by thrombin, was markedly reduced in TXA2- platelets. Antisera to Gq class alpha subunits abolished U46619-induced GTPase activity in TXA2-, TXA2+, and human platelets. Direct G protein stimulation by GTP gamma S yielded significantly less PA and IP3 in TXA2- platelets. Immunotransfer blotting revealed comparable quantities of Gq class alpha-subunits in all three platelet types. Thus, TXA2- dog platelets have impaired PI-PLC activation in response to TXA2/PGH2 receptor agonists secondary to G protein dysfunction, presumably involving a member of the Gq class. Images PMID:8227362

  8. Autologous Platelet Gel: Fad or Savoir? Do We Really Know?

    PubMed Central

    Stammers, Alfred H.; Trowbridge, Cody C.; Marko, Molly; Woods, Edward L.; Brindisi, Nicholas; Pezzuto, James; Klayman, Myra; Fleming, Sean; Petzold, Joseph

    2009-01-01

    Abstract: Autologous platelet-gel (APG) is the process of harvesting ones own cells (platelets), concentrating them most often through centrifugation, exposing them to an agonist which induces activation which releases intrinsic substances, and applying them to a target area to accelerate wound healing. APG is attractive because it concentrates a large number of biologically active substances, which are primarily proteins that participate in complex series of mechanisms involved in inflammation and wound healing. It has been used in numerous applications including sports medicine, dermatology, and surgery. However, there are few prospective randomized trials that have compared it in a rigorous manner to other techniques or to placebo. The following report is a review of APG, which includes a description of its perceived benefit, identification of the various modalities where it has been used, and criticisms concerning its use. PMID:20092084

  9. Platelet destruction in autoimmune thrombocytopenic purpura: kinetics and clearance of indium-111-labeled autologous platelets

    SciTech Connect

    Stratton, J.R.; Ballem, P.J.; Gernsheimer, T.; Cerqueira, M.; Slichter, S.J.

    1989-05-01

    Using autologous /sup 111/In-labeled platelets, platelet kinetics and the sites of platelet destruction were assessed in 16 normal subjects (13 with and three without spleens), in 17 studies of patients with primary autoimmune thrombocytopenic purpura (AITP), in six studies of patients with secondary AITP, in ten studies of patients with AITP following splenectomy, and in five thrombocytopenic patients with myelodysplastic syndromes. In normal subjects, the spleen accounted for 24 +/- 4% of platelet destruction and the liver for 15 +/- 2%. Untreated patients with primary AITP had increased splenic destruction (40 +/- 14%, p less than 0.001) but not hepatic destruction (13 +/- 5%). Compared with untreated patients, prednisone treated patients did not have significantly different spleen and liver platelet sequestration. Patients with secondary AITP had similar platelet counts, platelet survivals, and increases in splenic destruction of platelets as did patients with primary AITP. In contrast, patients with myelodysplastic syndromes had a normal pattern of platelet destruction. In AITP patients following splenectomy, the five nonresponders all had a marked increase (greater than 45%) in liver destruction compared to five responders (all less than 40%). Among all patients with primary or secondary AITP, there was an inverse relationship between the percent of platelets destroyed in the liver plus spleen and both the platelet count (r = 0.75, p less than 0.001) and the platelet survival (r = 0.86, p less than 0.001). In a stepwise multiple linear regression analysis, total liver plus spleen platelet destruction, the platelet survival and the platelet turnover were all significant independent predictors of the platelet count. Thus platelet destruction is shifted to the spleen in primary and secondary AITP. Failure of splenectomy is associated with a marked elevation in liver destruction.

  10. Indium-111 platelet imaging for detection of platelet deposition in abdominal aneurysms and prosthetic arterial grafts

    SciTech Connect

    Ritchie, J.L.; Stratton, J.R.; Thiele, B.; Haminton, G.W.; Warrick, L.N.; Huang, T.W.; Harker, L.A.

    1981-04-01

    Thirty-four platelet imaging studies were performed in 23 patients to determine whether platelet deposition could be detected in patients with vascular aneurysms (18 patients) or in patients in whom Dacron prosthetic grafts had been placed (5 patients). In patients in whom abnormal platelet deposition was detected, the effect of administration of platelet-active drugs on platelet deposition was examined. Of the 18 patients with an aneurysm, 12 had equivocally positive studies on initial imaging and 2 had equivocally positive images. Of five patients with Dacron arterial grafts in place, four had diffuse platelet deposition in the grafts; the fifth patient had a platelet deposition only in a pseudoaneurysm. Eight patients with an abdominal aneurysm and positive or equivocally positive baseline images were restudied during platelet-active drug therapy either with aspirin plus dipyridamole (seven patients) or with sulfinpyrazone (four patients). No patient studied during treatment with aspirin plus dipyridamole had detectably decreased platelet deposition compared with baseline determinations. In contrast, two of four patients studied while receiving sulfinpyrazone showed decreased platelet deposition. Thus, platelet imaging may be of value for studying platelet physiology in vivo and for assessing platelet-active drugs and the thrombogenicity of prosthetic graft materials in human beings.

  11. 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

  12. Copy Number Analysis of the Murine Platelet Proteome Spanning the Complete Abundance Range*

    PubMed Central

    Zeiler, Marlis; Moser, Markus; Mann, Matthias

    2014-01-01

    Knowledge of the identity and quantity of expressed proteins of a cell type is a prerequisite for a complete understanding of its molecular functions. Mass-spectrometry-based proteomics has allowed the identification of the entire protein complement of yeast and the close-to-complete set of proteins expressed in mammalian cell lines. Using recent technological advances, we here characterized the proteome of murine platelets, key actors in mediating hemostasis and thrombosis. We accurately measured the absolute protein concentrations of 13 platelet proteins using SILAC-protein epitope signature tags and used them as reference points to estimate the copy numbers of all proteins of the platelet proteome. To distinguish contaminants such as plasma or erythrocyte proteins from true platelet proteins, we monitored protein abundance profiles across multiple purification steps. In total, we absolutely quantified 4,400 platelet proteins, with estimated copy numbers ranging from less than 10 to about a million per cell. Stoichiometries derived from our data correspond well with previous studies. Our study provides a close-to-complete reference map of platelet proteins that will be useful to the community, for instance, for interpreting mouse models of human platelet diseases. PMID:25205226

  13. Syncytiotrophoblast Extracellular Vesicles from Pre-Eclampsia Placentas Differentially Affect Platelet Function

    PubMed Central

    Tannetta, Dionne S.; Hunt, Kathryn; Jones, Chris I.; Davidson, Naomi; Coxon, Carmen H.; Ferguson, David; Redman, Christopher W.; Gibbins, Jonathan M.; Sargent, Ian L.; Tucker, Katherine L.

    2015-01-01

    Pre-eclampsia (PE) complicates around 3% of all pregnancies and is one of the most common causes of maternal mortality worldwide. The pathophysiology of PE remains unclear however its underlying cause originates from the placenta and manifests as raised blood pressure, proteinuria, vascular or systemic inflammation and hypercoagulation in the mother. Women who develop PE are also at significantly higher risk of subsequently developing cardiovascular (CV) disease. In PE, the failing endoplasmic reticulum, oxidative and inflammatory stressed syncytiotrophoblast layer of the placenta sheds increased numbers of syncytiotrophoblast extracellular vesicles (STBEV) into the maternal circulation. Platelet reactivity, size and concentration are also known to be altered in some women who develop PE, although the underlying reasons for this have not been determined. In this study we show that STBEV from disease free placenta isolated ex vivo by dual placental perfusion associate rapidly with platelets. We provide evidence that STBEV isolated from normal placentas cause platelet activation and that this is increased with STBEV from PE pregnancies. Furthermore, treatment of platelets with aspirin, currently prescribed for women at high risk of PE to reduce platelet aggregation, also inhibits STBEV-induced reversible aggregation of washed platelets. Increased platelet reactivity as a result of exposure to PE placenta derived STBEVs correlates with increased thrombotic risk associated with PE. These observations establish a possible direct link between the clotting disturbances of PE and dysfunction of the placenta, as well as the known increased risk of thromboembolism associated with this condition. PMID:26551971

  14. 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

  15. Current trends in platelet transfusions practice: The role of ABO-RhD and human leukocyte antigen incompatibility

    PubMed Central

    Valsami, Serena; Dimitroulis, Dimitrios; Gialeraki, Argyri; Chimonidou, Maria; Politou, Marianna

    2015-01-01

    Platelet transfusions have contributed to the revolutionary modern treatment of hypoproliferative thrombocytopenia. Despite the long-term application of platelet transfusion in therapeutics, all aspects of their optimal use (i.e., in cases of ABO and/or Rh (D incompatibility) have not been definitively determined yet. We reviewed the available data on transfusion practices and outcome in ABO and RhD incompatibility and platelet refractoriness due to anti-human leukocyte antigen (HLA) antibodies. Transfusion of platelets with major ABO-incompatibility is related to reduced posttransfusion platelet (PLT) count increments, compared to ABO-identical and minor, but still are equally effective in preventing clinical bleeding. ABO-minor incompatible transfusions pose the risk of an acute hemolytic reaction of the recipient that is not always related to high anti-A, B donor titers. ABO-identical PLT transfusion seems to be the most effective and safest therapeutic strategy. Exclusive ABO-identical platelet transfusion policy could be feasible, but alternative approaches could facilitate platelet inventory management. Transfusion of platelets from RhD positive donors to RhD negative patients is considered to be effective and safe though is associated with low rate of anti-D alloimmunization due to contaminating red blood cells. The prevention of D alloimmunization is recommended only for women of childbearing age. HLA alloimmunization is a major cause of platelet refractoriness. Managing patients with refractoriness with cross-matched or HLA-matched platelets is the current practice although data are still lacking for the efficacy of this practice in terms of clinical outcome. Leukoreduction contributes to the reduction of both HLA and anti-D alloimmunization. PMID:26420927

  16. Current trends in platelet transfusions practice: The role of ABO-RhD and human leukocyte antigen incompatibility.

    PubMed

    Valsami, Serena; Dimitroulis, Dimitrios; Gialeraki, Argyri; Chimonidou, Maria; Politou, Marianna

    2015-01-01

    Platelet transfusions have contributed to the revolutionary modern treatment of hypoproliferative thrombocytopenia. Despite the long-term application of platelet transfusion in therapeutics, all aspects of their optimal use (i.e., in cases of ABO and/or Rh (D incompatibility) have not been definitively determined yet. We reviewed the available data on transfusion practices and outcome in ABO and RhD incompatibility and platelet refractoriness due to anti-human leukocyte antigen (HLA) antibodies. Transfusion of platelets with major ABO-incompatibility is related to reduced posttransfusion platelet (PLT) count increments, compared to ABO-identical and minor, but still are equally effective in preventing clinical bleeding. ABO-minor incompatible transfusions pose the risk of an acute hemolytic reaction of the recipient that is not always related to high anti-A, B donor titers. ABO-identical PLT transfusion seems to be the most effective and safest therapeutic strategy. Exclusive ABO-identical platelet transfusion policy could be feasible, but alternative approaches could facilitate platelet inventory management. Transfusion of platelets from RhD positive donors to RhD negative patients is considered to be effective and safe though is associated with low rate of anti-D alloimmunization due to contaminating red blood cells. The prevention of D alloimmunization is recommended only for women of childbearing age. HLA alloimmunization is a major cause of platelet refractoriness. Managing patients with refractoriness with cross-matched or HLA-matched platelets is the current practice although data are still lacking for the efficacy of this practice in terms of clinical outcome. Leukoreduction contributes to the reduction of both HLA and anti-D alloimmunization. PMID:26420927

  17. Full activation of mouse platelets requires ADP secretion regulated by SERCA3 ATPase-dependent calcium stores.

    PubMed

    Elaïb, Ziane; Adam, Frédéric; Berrou, Eliane; Bordet, Jean-Claude; Prévost, Nicolas; Bobe, Régis; Bryckaert, Marijke; Rosa, Jean-Philippe

    2016-08-25

    The role of the sarco-endoplasmic reticulum calcium (Ca(2+)) adenosine triphosphatase (ATPase) 3 (SERCA3) in platelet physiology remains poorly understood. Here, we show that SERCA3 knockout (SERCA3(-/-)) mice exhibit prolonged tail bleeding time and rebleeding. Thrombus formation was delayed both in arteries and venules in an in vivo ferric chloride-induced thrombosis model. Defective platelet adhesion and thrombus growth over collagen was confirmed in vitro. Adenosine 5'-diphosphate (ADP) removal by apyrase diminished adhesion and thrombus growth of control platelets to the level of SERCA3(-/-) platelets. Aggregation, dense granule secretion, and Ca(2+) mobilization of SERCA3(-/-) platelets induced by low collagen or low thrombin concentration were weaker than controls. Accordingly, SERCA3(-/-) platelets exhibited a partial defect in total stored Ca(2+) and in Ca(2+) store reuptake following thrombin stimulation. Importantly ADP, but not serotonin, rescued aggregation, secretion, and Ca(2+) mobilization in SERCA3(-/-) platelets, suggesting specificity. Dense granules appeared normal upon electron microscopy, mepacrine staining, and total serotonin content, ruling out a dense granule defect. ADP induced normal platelet aggregation, excluding a defect in ADP activation pathways. The SERCA3-specific inhibitor 2,5-di-(tert-butyl)-1,4-benzohydroquinone diminished both Ca(2+) mobilization and secretion of control platelets, as opposed to the SERCA2b inhibitor thapsigargin. This confirmed the specific role of catalytically active SERCA3 in ADP secretion. Accordingly, SERCA3-dependent Ca(2+) stores appeared depleted in SERCA3(-/-) platelets. Finally, αIIbβ3 integrin blockade did not affect SERCA3-dependent secretion, therefore proving independent of αIIbβ3 engagement. Altogether, these results show that SERCA3-dependent Ca(2+) stores control a specific ADP secretion pathway required for full platelet secretion induced by agonists at low concentration and independent

  18. Characteristics of the THERAFLEX UV-Platelets pathogen inactivation system - an update.

    PubMed

    Seghatchian, Jerard; Tolksdorf, Frank

    2012-04-01

    Considerable progress has been made in the last decade in producing purer, safer, leucocyte and plasma reduced platelet concentrates (PC) with an extended shelf life. The development of different pathogen inactivation technologies (PIT) has made a substantial contribution to this trend. Preceding platelet PIT (INTERCEPT Blood System/Cerus Corporation, Concord, CA, USA; MIRASOL/Caridian BCT, Lakewood, CO, USA) are based on adding a photosensitive compound to PC. The mixture is then activated by UV light in the UVB and/or UVA spectral regions. A novel procedure, THERAFLEX UV-Platelets (MacoPharma, Mouvaux, France), was recently developed that uses short-wave ultraviolet light (UVC), without addition of any photoactive agent. This technology has proven to be highly effective in sterilising bacteria (the major cause of morbidity/mortality after platelet transfusion) as well as inactivating other transfusion transmitted DNA/RNA containing pathogens and residual leucocytes. Any PIT reflects a balance between the efficacy of pathogen inactivation and preservation of platelet quality and function. A broad spectrum of in vitro tests have become available for the assessment of platelet storage lesion (PSL), aiming to better predict clinical outcome and untoward effects of platelet therapy. Recent paired studies on the release of platelet-derived cytokines, as new platelet performance indicators, revealed a parallel increase in both THERAFLEX UV-treated and control PC throughout storage, supporting the notion that the bioavailability of platelet function is not grossly affected by UVC treatment. This is corroborated by some newer technologies for proteomic analysis, showing that the THERAFLEX UV-Platelets system results in limited disruption of integrin-regulating extracellular disulfide bonds and minimal protein alterations when compared to UVB and gamma irradiation. Moreover, standard in vitro parameters reflecting activation, metabolic activity and function of platelets

  19. Targeting Phosphodiesterases in Anti-platelet Therapy

    PubMed Central

    Rondina, Matthew T.; Weyrich, Andrew S.

    2013-01-01

    There are two primary modes of platelet inhibition: blockade of membrane receptors or neutralization of intracellular pathways. Both means of inhibition have proven benefits in the prevention and resolution of atherothrombotic events. With regard to intracellular inhibition, phosphodiesterases (PDEs) are fundamental for platelet function. Platelets possess several PDEs (PDE2, PDE3 and PDE5) that catalyze the hydrolysis of cyclic adenosine 3′-5′-monophosphate (cAMP) and cyclic guanosine 3′-5′-monophosphate (cGMP), thereby limiting the levels of intracellular nucleotides. PDE inhibitors, such as cilostazol and dipyridamole, dampen platelet function by increasing cAMP and cGMP levels. This review focuses on the roles of PDE inhibitors in modulating platelet function, with particular attention paid to drugs that have anti-platelet clinical indications. PMID:22918733

  20. The Role of Platelets in Venous Thromboembolism.

    PubMed

    Montoro-García, Silvia; Schindewolf, Marc; Stanford, Sophia; Larsen, Ole Halfdan; Thiele, Thomas

    2016-04-01

    Multiple factors contribute to the risk of venous thromboembolism (VTE). Platelets have attracted much interest in arterial cardiovascular disease, whereas their role in VTE has received much less attention. Recent evidence suggests that platelets may play a more important role in VTE than previously anticipated. This review discusses the mechanisms that link platelets with venous thrombotic disease and their potential applications as novel risk factors for VTE. In addition, animal studies and randomized clinical trials that highlight the potential effect of antiplatelet therapy in venous thrombosis are evaluated to assess the role of platelets in VTE. The clinical significance of platelets for VTE risk assessment in specific patient cohorts and their role as a suitable therapeutic target for VTE prevention is acknowledged. The role of platelets in VTE is a promising field for future research. PMID:26926584

  1. Collagen-induced binding to human platelets of platelet-derived growth factor leading to inhibition of P43 and P20 phosphorylation

    SciTech Connect

    Bryckaert, M.C.; Rendu, F.; Tobelem, G.; Wasteson, A.

    1989-03-15

    Platelet-derived growth factor (PDGF) is known to inhibit collagen-induced platelet aggregation. Collagen-induced binding of /sup 125/I-PDGF to human washed platelets was therefore investigated. It was found to be time-dependent, reaching a plateau at 20 degrees C after 30 min, collagen concentration-dependent, specifically inhibited by unlabeled PDGF, and saturable. Scatchard plot analysis showed a single class of sites with 3000 +/- 450 molecules bound/cell and an apparent KD of 1.2 +/- 0.2 10(-8) M. The effects of PDGF on collagen-induced phosphoinositide breakdown and protein phosphorylation were also investigated. At 50 ng/ml PDGF, a concentration which completely inhibited collagen-induced aggregation, the breakdown of (/sup 32/P)phosphatidylinositol 4,5-biphosphate (PIP2) and (/sup 32/P)phosphatidylinositol 4-phosphate (PIP) was observed, but the subsequent replenishment of (/sup 32/P)PIP2 was inhibited. The same PDGF concentration totally inhibited collagen-induced phosphatidic acid formation. PDGF also completely prevented phosphorylation of P43 and P20, as a result of protein kinase C activation consecutive to phosphoinositide metabolism. These results suggest that a specific PDGF receptor can be induced by collagen, and PDGF can effect the early events of collagen-induced platelet activation by inhibiting PIP2 resynthesis and P43 and P20 phosphorylation. It is concluded that PDGF might be involved in a negative feed-back control of platelet activation.

  2. Evaluation of platelet cross-matching in the management of patients refractory to platelet transfusions

    PubMed Central

    Salama, Osama S.; Aladl, Doaa A.; El Ghannam, Doaa M.; Elderiny, Wesam E.

    2014-01-01

    Background Cross-match-compatible platelets are used to support thrombocytopenic patients who are refractory to randomly selected platelets. However, few studies have addressed the efficacy of using this strategy for patients requiring intensive platelet transfusion therapy. The aim of this study was to determine the effectiveness of cross-match-compatible platelets in an unselected group of patients refractory to platelets from random donors. Materials and methods A total of 406 cross-match-compatible platelet components were administered to 40 evaluable patients who were refractory to random-donor platelets. A solid-phase red cell adherence method was used for platelet cross-matching. The corrected count increment was used to monitor the effectiveness of each platelet transfusion. Multivariate analysis was performed to detect whether any variables could predict the response to transfusion. Results Statistically significant improvements were found in the mean corrected count increment when comparing cross-match-compatible platelets with randomly selected and incompatible platelets (p<0.001 for each). Compatible platelet transfusions were associated with a good response in 72.9% of cases while incompatible platelets were associated with a poor response in 66.7% of transfusion events (p<0.001). In the presence of clinical factors or alloimmunisation, compatible platelets were associated with good responses in 67.9% and 28.0% respectively vs 100% and 93.3% in their absence (p=0.009, p<0.001). Multivariate analysis revealed that cross-matching and alloimmunisation were the strongest predictors of transfusion response at 1 hour, while ABO compatibility, type of units received, followed by alloimmunisation then clinical factors were predictors at 24 hours. Discussion Platelet cross-matching using the solid-phase red cell adherence technique is an effective and rapid first-line approach for the management of patients refractory to platelet transfusions. PMID:24931840

  3. 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.

  4. Platelet mimicry: The emperor's new clothes?

    PubMed

    Moghimi, Seyed Moein; Hunter, Alan Christy; Peer, Dan

    2016-01-01

    Here we critically examine whether coating of nanoparticles with platelet membranes can truly disguise them against recognition by elements of the innate immune system. We further assess whether the "cloaking technology" can sufficiently equip nanoparticles with platelet-mimicking functionalities to include in vivo targeting of damaged blood vessels and binding to platelet-adhering opportunistic pathogens. We present views for improved, and pharmaceutically viable nanoparticle design strategies. PMID:26409192

  5. Activation and shedding of platelet glycoprotein IIb/IIIa under non-physiological shear stress.

    PubMed

    Chen, Zengsheng; Mondal, Nandan K; Ding, Jun; Koenig, Steven C; Slaughter, Mark S; Griffith, Bartley P; Wu, Zhongjun J

    2015-11-01

    The purpose of this study was to investigate the influence of non-physiological high shear stress on activation and shedding of platelet GP IIb/IIIa receptors. The healthy donor blood was exposed to three levels of high shear stresses (25, 75, 125 Pa) from the physiological to non-physiological status with three short exposure time (0.05, 0.5, 1.5 s), created by a specific blood shearing system. The activation and shedding of the platelet GPIIb/IIIa were analyzed using flow cytometry and enzyme-linked immunosorbent assay. In addition, platelet P-selectin expression of sheared blood, which is a marker for activated platelets, was also analyzed. The results from the present study showed that the number of activated platelets, as indicated by the surface GPIIb/IIIa activation and P-selectin expression, increased with increasing the shear stress level and exposure time. However, the mean fluorescence of GPIIb/IIIa on the platelet surface, decreased with increasing the shear stress level and exposure time. The reduction of GPIIb/IIIa on the platelet surface was further proved by the reduction of further activated platelet GPIIb/IIIa surface expression induced by ADP and the increase in GPIIb/IIIa concentration in microparticle-free plasma with increasing the applied shear stress and exposure time. It is clear that non-physiological shear stress induce a paradoxical phenomenon, in which both activation and shedding of the GPIIb/IIIa on the platelet surface occur simultaneously. This study may offer a new perspective to explain the reason of both increased thrombosis and bleeding events in patients implanted with high shear blood-contacting medical devices. PMID:26160282

  6. Platelet-type von Willebrand disease: a rare, often misdiagnosed and underdiagnosed bleeding disorder.

    PubMed

    Othman, Maha

    2011-07-01

    Platelet-type von Willebrand disease (PT-VWD) is an autosomal dominant rare bleeding disorder characterized by hyperresponsive platelets. This inherent platelet function defect is due to a gain-of-function mutation within the GP1BA gene coding for the platelet surface glycoprotein Ib alpha protein, the receptor for the adhesive protein von Willebrand factor (VWF). The defect results in excessive and unnecessary platelet-VWF interaction with subsequent removal of the hemostatically efficient high molecular weight VWF as well as platelets from the circulation, leading to thrombocytopenia and bleeding diathesis. Patients with PT-VWD present with mild to moderate mucocutaneous bleeding, which becomes more pronounced during pregnancy and following aspirin ingestion or drugs that have antiplatelet activity. Laboratory testing shows low VWF:ristocetin cofactor and low or normal VWF:antigen and characteristically an enhanced ristocetin-induced platelet agglutination (RIPA). These laboratory features are also indicators of the closely similar and more common bleeding disorder type 2B VWD. Simplified RIPA mixing assays, cryoprecipitate challenge, and flow cytometry can differentiate between the two disorders. However, the gold standard is to identify mutations within the VWF gene (indicating type 2B VWD) or the platelet GP1BA gene (confirming PT-VWD). Treatment is based on making a correct diagnosis of PT-VWD where platelet concentrates instead of VWF/factor VIII preparations should be administered. A recent fairly large retrospective/prospective registry-based international study showed that PT-VWD is very rare, likely to be misdiagnosed as type 2B VWD or idiopathic thrombocytopenic purpura, and represents 15% of type 2B VWD diagnoses. PMID:22102188

  7. Detection and partial characterization of an inhibitor of plasminogen activator in human platelets.

    PubMed Central

    Erickson, L A; Ginsberg, M H; Loskutoff, D J

    1984-01-01

    In this study, we demonstrate the presence of a previously undescribed fibrinolytic inhibitor in human serum. It has an apparent molecular weight of 50,000 and is not detected in serum derived from platelet-poor plasma, suggesting that it originates from platelets. This conclusion is supported by a number of observations. For example, extracts of washed, gel-filtered human platelets contain an inhibitor of similar activity and size, and physiological concentrations of thrombin induce its release from the platelets. Moreover, the kinetics and dose dependency of this release are similar to those observed for the release of platelet factor 4, and the release of both molecules is blocked by pretreating the platelets with prostaglandin E1 and theophylline. Mixing experiments, which were devised to investigate the specificity of the inhibitor, showed that the fibrinolytic activity initiated by both urokinase and tissue-type plasminogen activator was blocked by platelet releasate in a dose-dependent manner. In both cases, the amount of inhibition increased when the releasates were preincubated with the purified activators, indicating a direct interaction between the activators and an inhibitor(s). The inhibitory activity was removed by preincubating the releasates with antiserum prepared against an antiactivator purified from cultured bovine aortic endothelial cells. These results indicate that platelets contain an inhibitor which is released by thrombin, inhibits both urokinase and tissue-type plasminogen activator, and is immunologically similar to an inhibitor produced by endothelial cells. This molecule may represent a new class of inhibitors, the antiactivators, which function together with alpha 2-antiplasmin to regulate the fibrinolytic system of the blood. Its release from platelets by thrombin may protect the growing thrombus against premature dissolution initiated by plasminogen activators released by the endothelium. Images PMID:6434594

  8. The routine measurement of platelet size using sodium citrate alone as the anticoagulant.

    PubMed

    Bath, P M

    1993-10-18

    Mean platelet volume (MPV), a measure of platelet size, is becoming recognised as an important marker of platelet function. However, platelets swell in edetic acid (EDTA), the standard haematology anticoagulant, in a time-dependent manner making such measurements potentially unreliable. The effect of incubation time on MPV, and platelet distribution width (PDW), as measured in EDTA, low (1:9 volume/volume with blood) or high (1:4 v/v with blood) concentration sodium citrate was studied. MPV measured in high concentration sodium citrate did not change with time in contrast to MPV measured in either low concentration sodium citrate or EDTA which both increased in an inverse exponential fashion. MPV and PDW, measured in high concentration sodium citrate, had similar within-assay and between-assay coefficients of variation as other platelet, red cell and white cell haematology variables measured in EDTA: MPV 1.4%, 2.1%; PDW 1.4%, 1.5%; MCV 0.4%, 0.7%; PC 3.1%, 6.1%; WCC 1.5%, 7.3%; Hb 2.1%, 2.4% respectively. MPV measured in EDTA and corrected for incubation time approximated to, but was higher than, the MPV measured in high concentration sodium citrate. PDW correlated inversely with platelet count (r = -0.415, 2p < 0.001). MPV may be measured in sodium citrate (at 1:4 v/v with blood) alone with a better accuracy and reproducibility than similar measurements made in EDTA. Furthermore, such measurements are not influenced by incubation time, unlike for EDTA. PMID:8115997

  9. Platelet depletion and severity of streptococcal endocarditis

    PubMed Central

    Dall, Lawrence; Miller, Todd; Herndon, Betty; Diez, Ireneo; Dew, Michelle

    1998-01-01

    OBJECTIVE: To evaluate the importance of thrombocytopenia in streptococcal endocarditis using an animal model. DESIGN: A model of human septic endocarditis was established in rats (polyethylene catheters across the aortic valve and administration of Streptococcus sanguis, 5×107 colony forming units [cfu] intravenous). Thrombocytopenia at four levels was produced by antiplatelet serum. Secondary methods of producing thrombocytopenia were also evaluated. At sacrifice (96 h after platelet depletion and 72 h after infection), vegetations were removed, weighed, diluted, plated and counted. Potential mechanisms of the dose-response relationship between vegetation density and platelet count were evaluated. SETTING: Controlled research laboratory experiments. POPULATION STUDIED: Animal models of streptococcal endocarditis. MAIN RESULTS: The bacterial density of the aortic valve vegetations significantly increased as the platelet count decreased (P=0.0007). In severely thrombocytopenic animals (two-dose antiplatelet serum), data suggest increased vegetation embolism. Platelet depletion, which was minimal with chemical methods, was produced most effectively by antithrombocyte serum. Platelet surfaces in endocarditis were found to express elevated CD62p proteins (72.7% endocarditis, 34.7% control). Platelet protein fractions were evaluated in vitro by both streptocidal (P=0.19) and phagocytosis-stimulating assays. Platelet presence in mature aortic valve vegetations averaged only about 2%. CONCLUSIONS: In platelet depletion experiments using a rat model, a dose-response relationship of peripheral circulating platelet depletion to aortic valve vegetation density was found. The mechanism relating thrombocytopenia to endocarditis severity remains unresolved. PMID:22346555

  10. Platelets: covert regulators of lymphatic development.

    PubMed

    Bertozzi, Cara C; Hess, Paul R; Kahn, Mark L

    2010-12-01

    The field of platelet biology has rapidly expanded beyond the classical role of platelets in preventing blood loss and orchestrating clot formation. Despite the lack of transcriptional ability of these anuclear cell fragments, platelet function is now thought to encompass such diverse contexts as tissue repair, immune activation, primary tumor formation, and metastasis. Recent studies from multiple groups have turned the spotlight on an exciting new role for platelets in the formation of lymphatic vessels during embryonic development. Genetic experiments demonstrate that podoplanin, a transmembrane protein expressed on lymphatic endothelial cells, engages the platelet C-type lectin-like receptor 2 (CLEC-2) when exposed to blood, leading to SYK-SLP-76-dependent platelet activation. When components of this pathway are disrupted, aberrant vascular connections form, resulting in blood-lymphatic mixing. Furthermore, platelet-null embryos manifest identical blood-lymphatic mixing. The identification of platelets as the critical cell type mediating blood-lymphatic vascular separation raises new questions in our understanding of lymphatic development and platelet biology. PMID:21071706

  11. Computerised method for recording platelet density distribution.

    PubMed

    Järemo, P

    1995-05-01

    In the present study a computerized apparatus was employed for scanning light transmission variations along test tubes containing density-separated platelets. The device consists of a stepping motor, a stationary halogen lamp and a photopotentiometer connected to a personal computer. Anticoagulated whole blood was layered on a performed continuous Percoll gradient having a density span from 1090 kg/l (bottom) to 1040 kg/l (top). After centrifugation at 3400g for 1.5 hours, high-density cells (i.e. erythrocytes) pass through to the bottom of the test tube and the lighter platelets remain in the gradient. The test tube is moved by the computer between the halogen lamp and the photopotentiometer. Transmission variations along the gradient were recorded and registered in the computer. Density markers beads were used as an internal standard and platelet peak density was determined. After perforating the test tube the gradient was divided into 45 aliquots. In all fractions determination of platelet counts and mean platelet volume was carried out. In addition, in the aliquots having a platelet count > 20 x 10(12)/l the ratio beta-thromboglobulin per platelet was also determined. The platelet distribution in the gradient was illustrated graphically. A good agreement was found when comparing platelet distributions in the gradients and light transmission variations along the test tubes. PMID:7781754

  12. Effect of photodynamic therapy on mouse platelets

    NASA Astrophysics Data System (ADS)

    Zhou, Chuannong; Chi, Shunji; Deng, Jinsheng; Zhang, Hua; Liang, Junlin; Ha, Xian-wen

    1993-03-01

    Normal mice received hematoporphyrin derivative (10 mg/kg iv) immediately, 24 or 48 hrs prior to red light irradiation. The blood was collected and the platelet-rich plasma was irradiated by red light (100 J/cm2). The platelets were fixed immediately, 8 or 16 hrs after irradiation, and processed for EM examination. In comparison with those of control mice, the platelets of all experimental mice showed structural changes: 16 hrs after irradiation all platelets were necrotized; 8 hrs after irradiation almost one fourth of the platelets were necrotized and the remaining were considerably damaged; immediately after irradiation a small number of platelets became necrotic and most other platelets were swollen and deformed, often with many cytoplasmic projections and considerable dilatation of the canalicular membrane system. Our findings provided a clear evidence that platelets are highly sensitive to PDT action and can be directly and rapidly injured by PDT even in the absence of vascular endothelial cells. Our results give firm support to the hypothesis that both endothelial cells and platelets may play an important role in the initiation of early vascular damage and microcirculatory alterations induced by PDT in vivo.

  13. 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

  14. Effectiveness and efficiency of platelet rich plasma in the treatment of diabetic ulcers.

    PubMed

    Cobos, Raquel; Aizpuru, Felipe; Parraza, Naiara; Anitua, Eduardo; Orive, Gorka

    2015-01-01

    "There is a growing body of evidence suggesting that wound healing in chronic diabetic foot ulcers is growth factor dependent, and that the therapeutic delivery of these growth factors to wounds topically, has the potential ability to accelerate wound healing in conjunction with conventional wound care". There is, however, confusion about the utility of platelet rich plasma because the studies that have evaluated them use a wide range of products (different platelet and leukocyte concentrations, different techniques and frequencies of application, very heterogeneous simple, and different endpoints) making almost impossible to compare data and draw conclusions. In this study, we have analyzed the different platelet rich plasma products from a new perspective: cost-efficiency. According to our data, we observe that platelet rich plasma is a cost-effective option that allows faster healing of ulcers, and that should be taken into account in patients with long evolution ulcers. PMID:25934972

  15. 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

  16. [THE INFLUENCE OF HYDROGEN SULFIDE ON COLLAGEN-INDUCED AGGREGATION OF HUMAN PLATELETS].

    PubMed

    Petrova, I V; Trubacheva, O A; Mangataeva, O S; Suslova, T E; Kovalev, I V; Gusakova, S V

    2015-10-01

    Study the impact of hydrogen sulfide on collagen-induced platelet aggregation from healthy donors and patients with type 2 diabetes. In healthy individuals, in contrast to patients with type 2 diabetes, NaHS significantly inhibited platelet aggregation. Activators of cAMP signaling (forskolin and phosphodiesterase inhibitor) significantly reduced platelet aggregation in both groups of examinees. NO-synthase inhibitors increased platelet aggregation in healthy volunteers, but not in patients with type 2 diabetes. The presence of H2S donor did not alter the extent of platelet aggregation at high concentrations of cAMP or decreased production of nitric oxide. It is assumed that the antiplatelet effect of H2S is not associated with the effect on the signal system, mediated cAMP or nitric oxide. Change H2S-dependent regulation of platelet aggregation in patients with type 2 diabetes is caused by disorders have been reported with this disease: the increase of intracellular calcium ion concentration, oxidative damage to proteins, hyperhomocysteinemia, glycosylation of key proteins involved in this process. PMID:26827498

  17. Platelet-activating factor induces phospholipid turnover, calcium flux, arachidonic acid liberation, eicosanoid generation, and oncogene expression in a human B cell line

    SciTech Connect

    Schulam, P.G.; Kuruvilla, A.; Putcha, G.; Mangus, L.; Franklin-Johnson, J.; Shearer, W.T. )

    1991-03-01

    Platelet-activating factor is a potent mediator of the inflammatory response. Studies of the actions of platelet-activating factor have centered mainly around neutrophils, monocytes, and platelets. In this report we begin to uncover the influence of platelet-activating factor on B lymphocytes. Employing the EBV-transformed human B cell line SKW6.4, we demonstrate that platelet-activating factor significantly alters membrane phospholipid metabolism indicated by the incorporation of 32P into phosphatidylcholine, phosphatidylinositol, and phosphatidic acid but not significantly into phosphatidylethanolamine at concentrations ranging from 10(-9) to 10(-6) M. The inactive precursor, lyso-platelet-activating factor, at a concentration as high as 10(-7) M had no effect on any of the membrane phospholipids. We also show that platelet-activating factor from 10(-12) to 10(-6) M induced rapid and significant elevation in intracellular calcium levels, whereas lyso-platelet-activating factor was again ineffective. We further demonstrate the impact of platelet-activating factor binding to B cells by measuring platelet-activating factor induced arachidonic acid release and 5-hydroxyeicosatetraenoic acid production. Moreover, platelet-activating factor was capable of inducing transcription of the nuclear proto-oncogenes c-fos and c-jun. Finally we explored the possible role of 5-hydroxyeicosatetraenoic acid as a regulator of arachidonic acid liberation demonstrating that endogenous 5-lipoxygenase activity modulates platelet-activating factor induced arachidonic acid release perhaps acting at the level of phospholipase A2. In summary, platelet-activating factor is shown here to have a direct and profound effect on a pure B cell line.

  18. Busulfan Triggers Intrinsic Mitochondrial-Dependent Platelet Apoptosis Independent of Platelet Activation.

    PubMed

    Qiao, Jianlin; Wu, Yulu; Liu, Yun; Li, Xiaoqian; Wu, Xiaoqing; Liu, Na; Zhu, Feng; Qi, Kunming; Cheng, Hai; Li, Depeng; Li, Hongchun; Li, Zhenyu; Zeng, Lingyu; Ma, Ping; Xu, Kailin

    2016-09-01

    As a nonspecific alkylating antineoplastic agent, busulfan has been widely used in the treatment of patients with chronic myeloid leukemia. In vitro and in vivo studies demonstrated busulfan-induced cell apoptosis. Whether busulfan triggers platelet apoptosis remains unclear. This study aimed to evaluate the role of busulfan in platelet apoptosis. Isolated human platelets were incubated with busulfan followed by analysis of platelet apoptosis by flow cytometry or western blot, including mitochondrial depolarization, expression of Bcl-2, and Bax and caspase 3 activation. Meanwhile, platelet activation, expression of glycoprotein Ibα (GPIbα), glycoprotein VI (GPVI), and IIb3 and platelet aggregation in response to collagen and adenosine diphosphate (ADP) were measured. Additionally, busulfan was injected into mice with or without administration of caspase inhibitor QVD-Oph to investigate its effect on platelet lifespan. Our results showed that busulfan-treated platelets displayed increased mitochondrial membrane depolarization, decreased expression of Bcl-2, increased expression of Bax and caspase 3 activation in dose-dependent manner, which were inhibited by QVD-Oph. Platelet activation was not observed in busulfan-treated platelets as showed by no increased P-selectin expression and PAC-1 binding. However, busulfan reduced collagen- or ADP-induced platelet aggregation without affecting expression of GPIbα, GPVI, and IIb3. Furthermore, busulfan reduced circulating platelet lifespan which was ameliorated by QVD-Oph in mice. In conclusion, busulfan triggers mitochondrial-dependent platelet apoptosis and reduces platelet lifespan in mice. These data suggest targeting caspase activation might be beneficial in the prophylaxis of platelet apoptosis-associated thrombocytopenia after administration of busulfan. PMID:27292166

  19. Platelet transfusion in chemotherapy patients: comparison of the effect of intravenous infusion pumps versus gravity transfusion.

    PubMed

    Meess, A

    2015-01-01

    Platelet concentrates are given to patients suffering with severe thrombocytopenia usually by a gravity transfusion procedure. Increasing patient numbers that are in need of this treatment increase the pressure on hospital staff and space. In order to combat time issues, the use of medical devices such as intravenous infusion pumps are thought to be beneficial for time and simultaneously for safety in transfusion practices. By using infusion pumps, platelet concentrates can be transfused in less time and provide accurate volume measurements. Manufacturers of infusion pumps claim that these devices are safe to be used for blood products including platelet concentrates. However, published studies were performed on older models and newer devices are on the market now. The purpose of this study is to evaluate infusion pumps, which are claimed to be suitable for blood products and to investigate the impact the pumps had on platelets. Furthermore, the study revealed if the intravenous infusion pumps are safe to be used for platelet transfusion as claimed by manufacturers. A simulated transfusion was performed using the Carefusion Alaris GP Plus volumetric pump and Fresenius Kabi Volumat Agilia infusion pump. Samples were taken from expired platelet concentrates before and after passage through the pump. All samples were investigated for full blood count that included platelet count, mean platelet volume (MPV), platelet distribution width (PDW) and a plateletcrit (PCT). The samples were then centrifuged to achieve platelet-poor plasma and then tested for lactate dehydrogenase (LDH). A power calculation performed on the statistical power analysis program G*power indicated a requirement of 82 samples for a power of 80%. Statistical analysis was performed with the IBM SPSS statistic software. A paired sample t-test was used to calculate mean, standard deviation and P values for the infusion pumps used. The Wilcoxon Signed Rank Test was used to evaluate results that had a non

  20. Staphylococci-induced Human Platelet Injury Mediated by Protein A and Immunoglobulin G Fc Fragment Receptor

    PubMed Central

    Hawiger, Jack; Steckley, Sylvia; Hammond, Dianne; Cheng, Charles; Timmons, Sheila; Glick, Alan D.; Des Prez, Roger M.

    1979-01-01

    Bloodstream infections with staphylococci are accompanied by thromboembolic complications. We have studied the mechanism of the interaction of staphylococci with human blood platelets. Staphylococci that possess protein A, a bacterial receptor for the Fc fragment of immunoglobulin G (IgG), caused aggregation of human platelets in whole plasma accompanied by release of [3H]serotonin. These reactions were time and concentration dependent, requiring two or more staphylococci per platelet to give maximal response within 5 min. The interaction between staphylococci and platelets required the presence of cell wall-bound protein A and of IgG with an intact Fc fragment. It did not require an intact complement system. Cell wall-bound protein A (solid phase) was capable of aggregating human platelets in whole plasma. In contrast, free, solubilized protein A (fluid phase) did not cause measurable aggregation, and release of [3H]serotonin was reduced. An excess of free, solubilized protein A blocked aggregation of human platelets induced by staphylococci in whole plasma. The role of the Fc fragment of IgG in the staphylococci-human platelet interaction was demonstrated by an experiment in which free, isolated Fc fragment blocked aggregation of platelets in whole plasma induced by staphylococci. Furthermore, binding of 125I-protein A to human platelets was demonstrated in the presence of complete IgG with intact Fc fragment but not in the presence of the F(ab)2 fragment. Binding of the protein A-IgG complex to the human platelet Fc receptor was paralleled by the release of [3H]serotonin. These results represent a novel example of the interaction of two phylogenetically different Fc receptors, one on prokaryotic staphylococci and the other on human platelets. Their common ligand, IgG, is amplified by one Fc receptor (protein A) to react with another Fc receptor present on human platelets, which results in membrane-mediated aggregation and release reaction occurring in whole

  1. Proteome changes in platelets after pathogen inactivation--an interlaboratory consensus.

    PubMed

    Prudent, Michel; D'Alessandro, Angelo; Cazenave, Jean-Pierre; Devine, Dana V; Gachet, Christian; Greinacher, Andreas; Lion, Niels; Schubert, Peter; Steil, Leif; Thiele, Thomas; Tissot, Jean-Daniel; Völker, Uwe; Zolla, Lello

    2014-04-01

    Pathogen inactivation (PI) of platelet concentrates (PCs) reduces the proliferation/replication of a large range of bacteria, viruses, and parasites as well as residual leucocytes. Pathogen-inactivated PCs were evaluated in various clinical trials showing their efficacy and safety. Today, there is some debate over the hemostatic activity of treated PCs as the overall survival of PI platelets seems to be somewhat reduced, and in vitro measurements have identified some alterations in platelet function. Although the specific lesions resulting from PI of PCs are still not fully understood, proteomic studies have revealed potential damages at the protein level. This review merges the key findings of the proteomic analyses of PCs treated by the Mirasol Pathogen Reduction Technology, the Intercept Blood System, and the Theraflex UV-C system, respectively, and discusses the potential impact on the biological functions of platelets. The complementarities of the applied proteomic approaches allow the coverage of a wide range of proteins and provide a comprehensive overview of PI-mediated protein damage. It emerges that there is a relatively weak impact of PI on the overall proteome of platelets. However, some data show that the different PI treatments lead to an acceleration of platelet storage lesions, which is in agreement with the current model of platelet storage lesion in pathogen-inactivated PCs. Overall, the impact of the PI treatment on the proteome appears to be different among the PI systems. Mirasol impacts adhesion and platelet shape change, whereas Intercept seems to impact proteins of intracellular platelet activation pathways. Theraflex influences platelet shape change and aggregation, but the data reported to date are limited. This information provides the basis to understand the impact of different PI on the molecular mechanisms of platelet function. Moreover, these data may serve as basis for future developments of PI technologies for PCs. Further studies

  2. Mediators and molecular pathways involved in the regulation of neutrophil extracellular trap formation mediated by activated platelets.

    PubMed

    Carestia, Agostina; Kaufman, Tomás; Rivadeneyra, Leonardo; Landoni, Verónica Inés; Pozner, Roberto Gabriel; Negrotto, Soledad; D'Atri, Lina Paola; Gómez, Ricardo Martín; Schattner, Mirta

    2016-01-01

    In addition to being key elements in hemostasis and thrombosis, platelets amplify neutrophil function. We aimed to gain further insight into the stimuli, mediators, molecular pathways, and regulation of neutrophil extracellular trap formation mediated by human platelets. Platelets stimulated by lipopolysaccharide, a wall component of gram-negative bacteria, Pam3-cysteine-serine-lysine 4, a mimetic of lipopeptide from gram-positive bacteria, Escherichia coli, Staphylococcus aureus, or physiologic platelet agonists promoting neutrophil extracellular trap formation and myeloperoxidase-associated DNA activity under static and flow conditions. Although P-selectin or glycoprotein IIb/IIIa were not involved, platelet glycoprotein Ib, neutrophil cluster of differentiation 18, and the release of von Willebrand factor and platelet factor 4 seemed to be critical for the formation of neutrophil extracellular traps. The secretion of these molecules depended on thromboxane A(2) production triggered by lipopolysaccharide or Pam3-cysteine-serine-lysine 4 but not on high concentrations of thrombin. Accordingly, aspirin selectively inhibited platelet-mediated neutrophil extracellular trap generation. Signaling through extracellular signal-regulated kinase, phosphatidylinositol 3-kinase, and Src kinases, but not p38 or reduced nicotinamide adenine dinucleotide phosphate oxidase, was involved in platelet-triggered neutrophil extracellular trap release. Platelet-mediated neutrophil extracellular trap formation was inhibited by prostacyclin. Our results support a role for stimulated platelets in promoting neutrophil extracellular trap formation, reveal that an endothelium-derived molecule contributes to limiting neutrophil extracellular trap formation, and highlight platelet inhibition as a potential target for controlling neutrophil extracellular trap cell death. PMID:26320263

  3. Inhibition of the effects of thrombin on guinea pig platelets by the diacylglycerol lipase inhibitor RHC 80267

    SciTech Connect

    Amin, D.; Sutherland, C.A.; Khandwala, A.S.; Jamall, I.S.; Kapoor, A.L.

    1986-10-01

    Phospholipase C (PLC) and diacylglycerol lipase (DGL) activities were found in guinea pig platelet microsome preparations. No phospholipase A2 (PLA2) activity was detected. RHC 80267 (1,6-di (0-(carbamoyl) cyclohexanone oxime)hexane) inhibited DGL activity (IC50 = 4 uM) from guinea pig platelet microsomes but had no effect on PLC. RHC 80267 inhibited platelet aggregation (IC50 = 11 uM), release of arachidonic acid (AA), its metabolites, and ATP (IC50 = 4.5 uM) when guinea pig platelets were challenged with a low concentration of thrombin. We propose that PLC-DGL is an important enzymatic pathway for the release of AA in guinea pig platelets.

  4. Metalloproteolytic receptor shedding…platelets "acting their age".

    PubMed

    Andrews, Robert K; Gardiner, Elizabeth E

    2016-09-01

    Whilst significant effort has been focused on development of tools and approaches to clinically modulate activation processes that consume platelets, the platelet receptors that initiate activation processes remain untargeted. The modulation of receptor levels is also linked to underlying platelet aging processes which influence normal platelet lifespan and also the functionality and survival of stored platelets that are used in transfusion. In this review, we will focus on platelet adhesion receptors initiating thrombus formation, and discuss how regulation of levels of these receptors impact platelet function and platelet survival. PMID:27459696

  5. Comparison of common platelet receptors between the chacma baboon (Papio ursinus) and human for use in pre-clinical human-targeted anti-platelet studies.

    PubMed

    Janse van Rensburg, Walter J

    2016-06-01

    Anti-platelet agents play a central part in the treatment and prevention of acute thrombotic events. Discriminating animal models are needed for the development of novel agents. The chacma baboon has been extensively used as a model to evaluate anti-platelet agents. However, limited data exist to prove the translatability of this species to humans. We aimed to determine the suitability of the chacma baboon in preclinical human targeted GPIIb/IIIa, GPIbα and P2Y12 studies. Light-transmission platelet aggregometry (LTA), whole blood impedance aggregometry, receptor number quantification and genomic DNA sequencing were performed. Baboon ADP and arachidonic acid-induced LTA aggregation results differed significantly from human values, even at increased concentrations. LTA ristocetin-induced agglutination was comparable between species, but baboon platelets needed twice the concentration of ristocetin to elicit a similar response. Citrated baboon blood had significantly less aggregation than humans when evaluated with impedance aggregometry. However, hirudinised baboon whole blood gave similar aggregation as humans at the same agonist concentrations. GPIIb, GPIIIa and GPIbα numbers were significantly more on the baboon platelets. None of the amino acids deemed vital for receptor function, ligand binding or receptor inhibition, were radically different between the species. However, a conservative change in a calcium-binding region of GPIIb may render the baboon platelets more sensitive to calcium-binding agents. The chacma baboon may be used for the evaluation of human-targeted GPIIb/IIIa-, GPIbα- and P2Y12-inhibiting agents. However, the best anticoagulant, optimal agonist concentrations, increase in receptor number and sequence differences must be considered for any future studies. PMID:26559117

  6. Expansion of the neonatal platelet mass is achieved via an extension of platelet lifespan

    PubMed Central

    Liu, Zhi-Jian; Hoffmeister, Karin M.; Hu, Zhongbo; Mager, Donald E.; Ait-Oudhia, Sihem; Debrincat, Marlyse A.; Pleines, Irina; Josefsson, Emma C.; Kile, Benjamin T.; Italiano, Joseph; Ramsey, Haley; Grozovsky, Renata; Veng-Pedersen, Peter; Chavda, Chaitanya

    2014-01-01

    The fetal/neonatal hematopoietic system must generate enough blood cells to meet the demands of rapid growth. This unique challenge might underlie the high incidence of thrombocytopenia among preterm neonates. In this study, neonatal platelet production and turnover were investigated in newborn mice. Based on a combination of blood volume expansion and increasing platelet counts, the platelet mass increased sevenfold during the first 2 weeks of murine life, a time during which thrombopoiesis shifted from liver to bone marrow. Studies applying in vivo biotinylation and mathematical modeling showed that newborn and adult mice had similar platelet production rates, but neonatal platelets survived 1 day longer in circulation. This prolonged lifespan fully accounted for the rise in platelet counts observed during the second week of murine postnatal life. A study of pro-apoptotic and anti-apoptotic Bcl-2 family proteins showed that neonatal platelets had higher levels of the anti-apoptotic protein Bcl-2 and were more resistant to apoptosis induced by the Bcl-2/Bcl-xL inhibitor ABT-737 than adult platelets. However, genetic ablation or pharmacologic inhibition of Bcl-2 alone did not shorten neonatal platelet survival or reduce platelet counts in newborn mice, indicating the existence of redundant or alternative mechanisms mediating the prolonged lifespan of neonatal platelets. PMID:24599546

  7. Inhibition of platelet-aggregating activity in thrombotic thrombocytopenic purpura plasma by normal adult immunoglobulin G.

    PubMed Central

    Lian, E C; Mui, P T; Siddiqui, F A; Chiu, A Y; Chiu, L L

    1984-01-01

    Plasma from patients with thrombotic thrombocytopenic purpura (TTP) caused the aggregation of autologous and homologous platelets, and effect which was inhibited by normal plasma. IgG purified from seven normal adults at a concentration of 0.7 mg/ml completely inhibited the platelet aggregation induced by plasma obtained from two TTP patients with active disease. The inhibition of platelet aggregation by human adult IgG was concentration dependent, and the inhibitory activity of human IgG was neutralized by rabbit antihuman IgG. Fab fragments inhibited the TTP plasma-induced platelet aggregation as well as intact IgG, whereas Fc fragments had no effect. Platelet aggregation caused by ADP, collagen, epinephrine, or thrombin was not affected by purified human IgG. The prior incubation of IgG with TTP plasma caused a significantly greater reduction of platelet aggregation by TTP plasma than that of IgG and platelet suspension, suggesting that the IgG inhibits TTP plasma-induced platelet aggregation through direct interaction with platelet aggregating factor in TTP plasma. IgG obtained initially from five infants and young children under the age of 4 yr did not possess any inhibitory activity. When one of the children reached 3 yr of age, his IgG inhibited the aggregation induced by one TTP plasma, but not that caused by another plasma. The IgG procured from the same boy at 4 yr of age inhibited the aggregation induced by both TTP plasmas. The IgG purified from the TTP plasma during active disease failed to inhibit the aggregation caused by the same plasma. After recovery, however, the IgG effectively inhibited aggregation. These observations suggest that platelet-aggregating factors present in the TTP plasma are heterogeneous in nature and that the IgG present in the normal adult plasma, which inhibits the TTP plasma-induced platelet aggregation, may be partially responsible for the success of plasma infusion therapy in TTP. Images PMID:6538207

  8. IgG platelet antibodies in EDTA-dependent pseudothrombocytopenia bind to platelet membrane glycoprotein IIb.

    PubMed

    Fiorin, F; Steffan, A; Pradella, P; Bizzaro, N; Potenza, R; De Angelis, V

    1998-08-01

    EDTA-dependent pseudothrombocytopenia (PTCP) consists of an inappropriate low platelet count caused by autoantibodies present in the serum samples reacting with platelets only in EDTA-anticoagulated blood. By using immunoprecipitation and Western blot techniques, we studied the immunochemical specificity of platelet agglutinating autoantibodies in the serum samples of 10 patients with PTCP. Furthermore, to evaluate a possible role of PTCP-associated IgG autoantibodies in increased platelet turnover, we assayed the plasma glycocalicin (GC) level and calculated the GC index for every patient. Our results provide direct evidence that an epitope located on platelet membrane glycoprotein IIb is recognized by PTCP-associated IgG antibodies; moreover GC levels in patients with EDTA-dependent PTCP were similar to control levels, thus excluding an increased platelet turnover. We conclude that antiplatelet antibodies directed against platelet cryptantigens are unlikely to have a major role in the increased removal of cells from circulation. PMID:9704616

  9. Interference of anti-inflammatory and anti-asthmatic drugs with neutrophil-mediated platelet activation: singularity of azelastine.

    PubMed Central

    Renesto, P.; Balloy, V.; Vargaftig, B. B.; Chignard, M.

    1991-01-01

    1. The capacity of various drugs (acetylsalicylic acid (ASA), ketoprofen, diclofenac, piroxicam, BW 755C, BW A4C, nedocromil sodium and azelastine) to inhibit human polymorphonuclear neutrophil (PMN)-mediated platelet activation was investigated. In this model, stimulated PMN release cathepsin G (Cat G), a serine proteinase which, in turn, induces platelet activation. 2. Among the different tested drugs, azelastine (100 microM for 1 min) was the only one able to prevent platelet aggregation. The cyclo-oxygenase inhibitors were all inactive, although used at effective concentrations as judged by inhibition of thromboxane B2 (TxB2) formation. Inhibition of platelet aggregation by azelastine was concentration-dependent, the range of active concentrations being of 20-70 microM. Release from platelets of 5-hydroxytryptamine was also inhibited at 30 microM and above, but never reached 100%. 3. The inhibition by azelastine is due to an effect on both cells. Indeed, beta-glucuronidase release from activated PMN and platelet activation by purified Cat G were both affected. 4. However, used at high concentrations (greater than 100 microM) azelastine was toxic since it released significant amounts of lactate dehydrogenase (LDH) from PMN and platelets. 5. These results show the capacity of azelastine, an anti-allergic and anti-asthmatic compound, to inhibit the cell-to-cell communication between PMN and platelets, an effect which may be relevant for its therapeutic efficacy or for a new application in diseases in which PMN and platelets are involved. PMID:1653073

  10. Reticulated platelets: analytical aspects and clinical utility.

    PubMed

    Hoffmann, Johannes J M L

    2014-08-01

    Reticulated platelets are immature platelets circulating in blood; they reflect the activity of megakaryopoiesis in the bone marrow. Therefore, they can be used as a non-invasive test in patients with thrombocytopenia in various clinical conditions. The preferred method of analysis is by flow cytometry. However, there is an evident lack of analytical standardization, making it difficult to compare results obtained in different laboratories. Currently, two types of hematology analyzers are on the market offering fully automated measurement of reticulated or immature platelets: the high end analyzers manufactured by Sysmex (XE- and XN-series) and Abbott (CELL-DYN Sapphire). Although the methods are essentially different and cannot be used interchangeably, both have been proven to have clinical utility. Reticulated or immature platelet assays are useful for the differential diagnosis of thrombocytopenia and for monitoring bone marrow recovery after chemotherapy or stem cell transplantation. These assays may aid clinicians in platelet transfusion decisions when recovery from thrombocytopenia is imminent. In addition, preliminary findings indicate that there is a rationale for reticulated or immature platelets for risk stratification in acute coronary syndromes and for monitoring the effect of treatment with antiplatelet drugs in patients with coronary artery diseases. The aim of this paper is to present the present technology available for measuring reticulated platelets as well as an overview of the current status of clinical application. This overview also indicates that more research is needed before reticulated or immature platelet assays can be applied in other clinical conditions than thrombocytopenia and after transplantation. PMID:24807169

  11. Platelets and fibrin strands during clot retraction.

    PubMed

    Morgenstern, E; Korell, U; Richter, J

    1984-03-15

    The ultrastructure of platelet fibrin contacts (PFC) and the course of the strands was investigated in serial sections of retracted clots with the help of specimen tilting. We found after retraction in a test tube as well as under isometric conditions in the resonance thrombograph, after HARTERT, an uniform type of PFC. The side to side contact between platelet surface and fibrin strands displayed a 15 nm wide space which was bridged of 10 - 30 nm by filamentary structure. In each case the direction of the fibrin strands changed on contact with the platelet surface (bend). These bends recurred if the adhering strands ran over a longer distance on the platelet surface. The bends can be explained by non-directional movement of the platelets or of their pseudopodia. Microfilaments (actomyosin) which run straight in pseudopodia and often also twisted in the platelet body support this assumption. The described mechanism - contact of the thrombin activated platelets with fibrin strands and simultaneous nondirectional movement of the platelets which bind further sections of the adhering strands to their surface - would provide a more satisfactory explanation for the retraction of the clot to 1/10 of its original volume. PMID:6539004

  12. Platelet generation in vivo and in vitro.

    PubMed

    Wang, Biao; Zheng, Jiansheng

    2016-01-01

    Platelet (PLT) transfusion, which is the primary cell therapy for thrombocytopenia, has been a source of concern in recent years due to its limitations of donor-dependent supply and soaring costs. In vitro platelet generation on an industrial scale is a possible solution requiring exploration. The technology of platelet generation ex vivo has been widely studied across the world, though the mechanisms of physiological thrombopoiesis and platelet biology function in vivo still remain elusive today. Various culture systems have been studied, most of which proved quite inefficient in generating functional platelets ex vivo, so there is still a long way to reach our ultimate goal of generating a fully functional platelet in vitro on an industrial scale. This review integrates the latest research into physiological platelet biogenesis and ex vivo-platelet/megakaryocyte (MK) generation protocols with a focus on the ability to generate PLT/MK in large quantities, summarizes current culture systems based on induced human pluripotent stem cells and adipose-derived stem cells, and discusses significant challenges that must be overcome for these approaches to be perfected. PMID:27390629

  13. Titanium surface hydrophilicity enhances platelet activation.

    PubMed

    Alfarsi, Mohammed A; Hamlet, Stephen M; Ivanovski, Saso

    2014-01-01

    Titanium implant surface modification is a key strategy used to enhance osseointegration. Platelets are the first cells that interact with the implant surface whereupon they release a wide array of proteins that influence the subsequent healing process. This study therefore investigated the effect of titanium surface modification on the attachment and activation of human platelets. The surface characteristics of three titanium surfaces: smooth (SMO), micro-rough (SLA) and hydrophilic micro-rough (SLActive) and the subsequent attachment and activation of platelets following exposure to these surfaces were determined. The SLActive surface showed the presence of significant nanoscale topographical features. While attached platelets appeared to be morphologically similar, significantly fewer platelets attached to the SLActive surface compared to both the SMO and SLA surfaces. The SLActive surface however induced the release of the higher levels of chemokines β-thromboglobulin and platelet factor 4 from platelets. This study shows that titanium surface topography and chemistry have a significant effect on platelet activation and chemokine release. PMID:25311339

  14. Fractal and Euclidean descriptors of platelet shape.

    PubMed

    Kraus, Max-Joseph; Neeb, Heiko; Strasser, Erwin F

    2014-01-01

    Platelet shape change is a dynamic membrane surface process that exhibits remarkable morphological heterogeneity. Once the outline of an irregular shape is identified and segmented from a digital image, several mathematical descriptors can be applied to numerical characterize the irregularity of the shapes surface. 13072 platelet outlines (PLO) were segmented automatically from 1928 microscopic images using a newly developed algorithm for the software product Matlab R2012b. The fractal dimension (FD), circularity, eccentricity, area and perimeter of each PLO were determined. 972 PLO were randomly assigned for computer-assisted manual measurement of platelet diameter as well as number, width and length of filopodia per platelet. FD can be used as a surrogate parameter for determining the roughness of the PLO and circularity can be used as a surrogate to estimate the number and length of filopodia. The relationship between FD and perimeter of the PLO reveals the existence of distinct groups of platelets with significant structural differences which may be caused by platelet activation. This new method allows for the standardized continuous numerical classification of platelet shape and its dynamic change, which is useful for the analysis of altered platelet activity (e.g. inflammatory diseases, contact activation, drug testing). PMID:24224894

  15. Relation of platelet density to platelet age: survival of low- and high-density 111indium-labeled platelets in baboons

    SciTech Connect

    Savage, B.; McFadden, P.R.; Hanson, S.R.; Harker, L.A.

    1986-08-01

    The relationship between platelet density and platelet age has been studied using continuous linear Percoll density gradients and 111In-labeling of autologous platelets in baboons. To investigate changes in platelet density during senescence in the circulation, baboons were infused with 111In-labeled autologous platelets, and blood was collected at one hour postinfusion and twice daily thereafter for six days. Platelets were isolated from these samples in high yield (greater than 95%) and separated in continuous linear Percoll density gradients following density equilibrium centrifugation. Although at one hour postinfusion the density distribution of radiolabeled platelets coincided closely with the distribution of the total platelet population, a detectable symmetrical shift toward higher densities was observed after five days. The relative specific radioactivity (RSR) of high-density platelets (1.064 to 1.067 g/mL) decreased at a slower rate than that of the total platelet population (platelets of all densities), whereas the RSR of low-density platelets (1.053 to 1.056 g/mL) showed a more immediate and rapid decrease. These results give rise to one of two interpretations: (1) low-density platelets have a shorter survival time than more dense platelets and are therefore cleared from the circulation at a faster rate, or (2) platelets of all densities increase in density upon aging in the circulation. To determine the explanation for changing RSR of different density fractions we studied the in vivo disappearance characteristics of low- and high-density 111In-labeled platelets. There were no significant differences between the mean survival times of low-density platelets (5.0 +/- 0.49 days, +/- 1 SD, n = 6), high-density platelets (4.9 +/- 0.56 days, n = 6), or control platelets representing platelets of all densities (4.9 +/- 0.38 days, n = 6).

  16. Dermcidin isoform-2 induced nullification of the effect of acetyl salicylic acid in platelet aggregation in acute myocardial infarction

    PubMed Central

    Bank, Sarbashri; Jana, Pradipta; Maiti, Smarajit; Guha, Santanu; Sinha, A. K.

    2014-01-01

    The aggregation of platelets on the plaque rupture site on the coronary artery is reported to cause both acute coronary syndromes (ACS) and acute myocardial infarction (AMI). While the inhibition of platelet aggregation by acetyl salicylic acid was reported to produce beneficial effects in ACS, it failed to do in AMI. The concentration of a stress induced protein (dermcidin isoform-2) was much higher in AMI than that in ACS. Incubation of normal platelet rich plasma (PRP) with dermcidin showed one high affinity (Kd = 40 nM) and one low affinity binding sites (Kd = 333 nM). When normal PRP was incubated with 0.4 μM dermcidin, the platelets became resistant to the inhibitory effect of aspirin similar to that in the case of AMI. Incubation of PRP from AMI with dermcidin antibody restored the sensitivity of the platelets to the aspirin effect. Incubation of AMI PRP pretreated with 15 μM aspirin, a stimulator of the NO synthesis, resulted in the increased production of NO in the platelets that removed the bound dermcidin by 40% from the high affinity binding sites of AMI platelets. When the same AMI PRP was retreated with 10 μM aspirin, the aggregation of platelets was completely inhibited by NO synthesis. PMID:25055737

  17. Relationship between potential platelet activation and LCS

    NASA Astrophysics Data System (ADS)

    Shadden, Shawn

    2010-11-01

    In the study of blood flow, emphasis is often directed at understanding shear stress at the vessel wall due to its potentially disruptive influence on the endothelium. However, it is also known that shear stress has a potent effect on platelet activation. Platelet activation is a precursor for blood clotting, which in turn is the cause of most forms of death. Since most platelets are contained in the flow domain, it is important to consider stresses acting on the platelet as they are convected. Locations of high stress can correspond to boundaries between different dynamic regions and locations of hyperbolic points in the Eulerian sense. In the computation of LCS, strain in typically considered in the Lagrangian sense. In this talk we discuss the relationship between locations of potential platelet activation due to increased stress and locations of LCS marking increase Lagrangian deformation.

  18. Platelet Indices of Selenium Status in Healthy and Selenium-Deficient Sheep: a Comparison with Selenium Indices in Plasma, Whole Blood, and Red Blood Cells.

    PubMed

    Dalir-Naghadeh, Bahram; Bahrami, Yaser; Rezaei, Siamak Asri; Anassori, Ehsan; Janalipour, Ali; Khosravi, Voria

    2015-11-01

    Several biomarkers have been used to evaluate selenium (Se) status in livestock. However, there is no report on the potential usefulness of the Se indices of platelets in diagnosis of Se deficiency in large animals. In the current study, Se concentration and glutathione peroxidase (GPx) activity in platelets of 38 healthy and 142 Se-deficient ewes were assessed, and their correlation with plasma Se concentration, plasma GPx activity, whole blood Se concentration, and erythrocyte GPx activity was determined. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff values of Se concentration and GPx activity of the platelets and to summarize the diagnostic performance of these biomarkers. In Se-deficient ewes, consistent with other indices, Se concentration and GPx activity in platelets were significantly lower than those of the healthy ewes. There was a positive significant correlation between Se concentration and GPx activity in platelets with plasma Se concentration, whole blood Se concentration, and erythrocyte GPx activity. Based on the ROC curve analysis, the best cutoff value to predict inadequate plasma selenium concentration was ≤0.0055 attogram/platelet for the platelet Se concentration, with a sensitivity of 100.0 %, specificity of 92.4 %, and AUC of 0.94. For platelet GPx activity, the cutoff value was ≤203.6 U/g protein with a sensitivity of 97.4 %, specificity of 77.7 %, and AUC of 0.90. The results of this study suggested that the platelet Se concentration and GPx activity can be considered a reliable and valid intermediate-term surrogate parameter in assessment of dietary Se intake in sheep. PMID:25900578

  19. Platelets and coagulation in infection

    PubMed Central

    Davis, Rachelle P; Miller-Dorey, Sarah; Jenne, Craig N

    2016-01-01

    Disseminated intravascular coagulation (DIC) is a frequent complication in sepsis that is associated with worse outcomes and higher mortality in patients. In addition to the uncontrolled generation of thrombi throughout the patient's vasculature, DIC often consumes large quantities of clotting factors leaving the patient susceptible to hemorrhaging. Owing to these complications, patients often receive anticoagulants to treat the uncontrolled clotting, often with mixed outcomes. This lack of success with the current array of anticoagulants can be partly explained by the fact that during sepsis clotting is often initiated by the immune system. Systemic inflammation has the capacity to activate and amplify coagulation and, as such, potential therapies for the treatment of sepsis-associated DIC need to address the interaction between inflammation and coagulation. Recent studies have suggested that platelets and neutrophil extracellular traps (NETs) are the key mediators of infection-induced coagulation. This review explores current anticoagulant therapies and discusses the development of future therapies to target platelet and NET-mediated coagulation. PMID:27525062

  20. Platelet interaction within giant intracranial aneurysms

    SciTech Connect

    Sutherland, G.R.; King, M.E.; Peerless, S.J.; Vezina, W.C.; Brown, G.W.; Chamberlain, M.J.

    1982-01-01

    Turbulence within intracranial aneurysms may result in tearing of the aneurysmal wall, exposing the subendothelial matrix to circulating platelets. In this study, platelet interaction in giant intracranial aneurysms was evaluated by a dual-isotope technique employing In-labeled platelets and Tc-labeled red blood cells. The use of two isotopes allows the subtraction of the blood pool and the calculation of the ratio indium deposited:indium blood pool (In(D)/In(BP)). A ratio greater than zero indicates platelet deposition within aneurysm. Thirteen patients were evaluated in this way, with platelet deposition demonstrated in six. In these six patients, the ratio In(D)/In(BP) was found to be significantly elevated, with a mean value of 0.96 +/- 0.65. Three of these six patients has symptoms of recurrent transient neurological deficits; one of these three suffered a complete stroke following documentation of platelet deposition. In this case, the aneurysm was obtained at surgery and was found to contain intraluminal platelet aggregation when viewed by scanning electron microscopy. In the remaining seven patients, the ratio IN(D)/In(BP) was found not to be significantly elevated (mean -0.03 and/- 0.06), indicating the absence of active platelet deposition. Two of these patients had prior symptoms of cerebral ischemia; one of these was found to have an ulcer in the ipsilateral internal carotid artery which was probably responsible for thromboembolic events to the hemisphere. The authors conclude that platelet aggregation occurs more frequently than previously recognized in giant intracranial aneurysms, and their data substantiate the hypothesis that platelet metabolic products or thrombi originating from a large aneurysm may embolize to distal cerebral vessels.

  1. Metabolism of arachidonic acid by macaque platelets. Implications for studies on atherosclerosis.

    PubMed

    Beatty, C H; Howard, C F; Hoskins, M K; Herrington, P T

    1985-04-01

    The metabolism of [1-14C]arachidonic acid [( 1-14C]AA) by washed platelets from macaques and human subjects was investigated. The results were as follows: At substrate levels of 1 microM, similar amounts of prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), prostaglandin D2 (PGD2), and thromboxane A2 (TXA2), measured as thromboxane B2 (TXB2), were produced from [1-14C]AA by platelets from rhesus, Celebes black, and cynomolgus macaques and humans. An increase in the AA concentration from 1 microM to 20 microM decreased the TXB2: PGD2 ratio (aggregator: antiaggregator) from greater than 5 to less than 2 in all series. In the human series, the ratio decrease was due to an increase in PGD2 production; in the macaque series, PGD2 production increased and TXB2 production decreased. Under basal conditions and at 1 microM AA concentrations, the amounts of prostaglandins and thromboxanes produced by platelets from male and female rhesus macaques were the same. An increase in substrate concentration from 1 microM to 20 microM AA decreased TXB2 production and increased PGD2 production to the same extent in platelets from male and female rhesus macaques. Imidazole increased prostaglandin production and decreased TXB2 production by platelets from both male and female rhesus macaques. The TXB2: PGD2 ratios were reduced below 1.5; there was no difference between the ratios in the two series. In the presence of 1 mM imidazole, greater amounts of prostaglandins and thromboxanes were produced in the male than in the female series. These data indicate that macaque's platelets are a suitable model for the study of AA metabolism in human platelets. PMID:3924062

  2. 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

  3. 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

  4. 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 m